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1.  Serologic Evidence of Infections and Type 2 Diabetes: The MultiEthnic Study of Atherosclerosis 
Prospective studies have identified chronic inflammation as a risk factor for type 2 diabetes. However, it is not known whether infection by specific pathogens or having a greater “pathogen burden” is associated with diabetes. The aim of this study was to examine the cross-sectional relation of seropositivity to five pathogens (C. pneumoniae, cytomegalovirus, H. pylori, hepatitis A virus, herpes simplex virus) and prevalent diabetes.
Baseline data from a random sample of MultiEthnic Study of Atherosclerosis (MESA) participants (n=1,000; age: 45-84) were used. Diabetes was defined by ADA 2003 criteria, and “pathogen burden” by the number of pathogens (0–5) for which an individual was seropositive. Logistic regression was used to test differences in diabetes prevalence by seropositivity. Linear regression was used to explore associations between pathogen seropositivity and the inflammation markers CRP, IL-6, and fibrinogen.
Diabetes prevalence was 12.7%, while seropositivity for C. pnuemoniae was 76%, cytomegalovirus 77%, H. pylori 45%, hepatitis A 58%, and herpes simplex virus 85%. 72% were seropositive for ≥3 pathogens. In crude analyses, the prevalence of diabetes was higher among those with a pathogen burden ≥3, and with seropositivity to cytomegalovirus, H. pylori, hepatitis A, and herpes simplex virus. After adjustment for demographic covariates (particularly race) all associations became nonsignificant. Pathogen seropositivity was also not related to inflammation marker levels.
Following demographic adjustments, no associations were observed between infection by several pathogens and diabetes status, suggesting no etiologic role for them in the occurrence of diabetes.
PMCID: PMC2679689  PMID: 19236617
diabetes; infection; pathogen; seropositivity
2.  Pathogen burden, cytomegalovirus infection and inflammatory markers in the risk of premature coronary artery disease in individuals of Indian origin 
Coronary artery disease (CAD) occurs at an earlier age in South Asians compared with other ethnic groups. Infection and inflammation show a positive association with the disease.
To investigate the association of infection and inflammatory markers with premature CAD in the Indian Atherosclerosis Research Study population.
Antibody titres for Chlamydia pneumoniae, cytomegalovirus (CMV), Helicobacter pylori, herpes simplex virus and levels of interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP), fibrinogen and secretory phospholipase A2, were measured in 866 individuals (433 CAD patients and matched controls). All individuals were followed-up for recurrent cardiac events for four years. ANOVA was used to study the association of infection and inflammation with CAD.
The present study found that the odds of CAD occurrence was 2.42 (95% CI 1.26 to 4.64; P<0.008), with all four infections and increased in the presence of hsCRP (OR 4.67 [95% CI 1.43 to 15.25]); P=0.011). Only anti-CMV antibody levels were a significant risk factor for CAD occurrence (OR 2.23 [95% CI 1.20 to 4.15]; P=0.011) and recurrent cardiac events (OR 1.94 [95% CI 0.85 to 4.45]; P=0.015). Mean values of the inflammatory biomarkers IL-6 (P=0.035), fibrinogen (P=0.014), hsCRP (P=0.010) and secretory phospholipase A2 (P=0.002) increased with CMV antibody levels. Incorporating hsCRP and IL-6 in the risk prediction models significantly increased the OR to 2.56 (95% CI 1.16 to 5.63; P=0.019) with a c statistic of 0.826.
Pathogen burden, especially CMV infection in combination with inflammatory markers, is a significant predictor of CAD risk in the young Indian population.
PMCID: PMC3395457  PMID: 22826649
Coronary artery disease; C-reactive protein; Cytomegalovirus; Inflammatory markers; Pathogen burden
3.  Socioeconomic and Psychosocial Gradients in Cardiovascular Pathogen Burden and Immune Response: The Multi-Ethnic Study of Atherosclerosis 
Brain, behavior, and immunity  2008;23(5):663-671.
The biologic mechanisms linking socioeconomic position and psychosocial factors to cardiovascular disease (CVD) are not well understood. Immune response to persistent pathogens may be one of these mechanisms.
We analyzed cross-sectional data from the Multi-Ethnic Study of Atherosclerosis (N=999) composed of adults age 45–84. Log-binomial regression and ordinal logistic regression models were used to examine associations of socioeconomic factors and psychosocial factors with pathogen burden and immune response among those infected. Pathogen burden was assessed based on seroprevalence of Helicobacter pylori, cytomegalovirus, herpes simplex virus-1, and Chlamydia pneumoniae and antibody levels were used to characterize high immune response to all four pathogens.
Low education was a strong and significant independent predictor of higher pathogen burden after adjustment for covariates (adjusted odds ratio (OR) 95% confidence interval (CI) 1.37, 1.19–1.57). Among subjects seropositive for all four pathogens, low education and a higher level of chronic psychosocial stress showed a positive association with higher antibody response, although associations were no longer significant in models with all covariates included (OR = 1.64, 95%CI 0.82–3.31 for lowest vs. highest educational category and OR= 1.29, 95%CI 0.96–1.73 for a one level increase in chronic stress).
Pathogen burden and heightened immune response may represent a biological pathway by which low socioeconomic position and chronic stress are related to increased rates of cardiovascular disease.
PMCID: PMC2694852  PMID: 19150399
Infection; inflammation; epidemiology; cardiovascular diseases
4.  Are Markers of Inflammation More Strongly Associated with Risk for Fatal Than for Nonfatal Vascular Events? 
PLoS Medicine  2009;6(6):e1000099.
In a secondary analysis of a randomized trial comparing pravastatin versus placebo for the prevention of coronary and cerebral events in an elderly at-risk population, Naveed Sattar and colleagues find that inflammatory markers may be more strongly associated with risk of fatal vascular events than nonfatal vascular events.
Circulating inflammatory markers may more strongly relate to risk of fatal versus nonfatal cardiovascular disease (CVD) events, but robust prospective evidence is lacking. We tested whether interleukin (IL)-6, C-reactive protein (CRP), and fibrinogen more strongly associate with fatal compared to nonfatal myocardial infarction (MI) and stroke.
Methods and Findings
In the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER), baseline inflammatory markers in up to 5,680 men and women aged 70–82 y were related to risk for endpoints; nonfatal CVD (i.e., nonfatal MI and nonfatal stroke [n = 672]), fatal CVD (n = 190), death from other CV causes (n = 38), and non-CVD mortality (n = 300), over 3.2-y follow-up. Elevations in baseline IL-6 levels were significantly (p = 0.0009; competing risks model analysis) more strongly associated with fatal CVD (hazard ratio [HR] for 1 log unit increase in IL-6 1.75, 95% confidence interval [CI] 1.44–2.12) than with risk of nonfatal CVD (1.17, 95% CI 1.04–1.31), in analyses adjusted for treatment allocation. The findings were consistent in a fully adjusted model. These broad trends were similar for CRP and, to a lesser extent, for fibrinogen. The results were also similar in placebo and statin recipients (i.e., no interaction). The C-statistic for fatal CVD using traditional risk factors was significantly (+0.017; p<0.0001) improved by inclusion of IL-6 but not so for nonfatal CVD events (p = 0.20).
In PROSPER, inflammatory markers, in particular IL-6 and CRP, are more strongly associated with risk of fatal vascular events than nonfatal vascular events. These novel observations may have important implications for better understanding aetiology of CVD mortality, and have potential clinical relevance.
Please see later in the article for Editors' Summary
Editors' Summary
Cardiovascular disease (CVD)—disease that affects the heart and/or the blood vessels—is a common cause of death in developed countries. In the USA, for example, the leading cause of death is coronary heart disease (CHD), a CVD in which narrowing of the heart's blood vessels by “atherosclerotic plaques” (fatty deposits that build up with age) slows the blood supply to the heart and may eventually cause a heart attack (myocardial infarction). Other types of CVD include stroke (in which atherosclerotic plaques interrupt the brain's blood supply) and heart failure (a condition in which the heart cannot pump enough blood to the rest of the body). Smoking, high blood pressure, high blood levels of cholesterol (a type of fat), having diabetes, and being overweight all increase a person's risk of developing CVD. Tools such as the “Framingham risk calculator” take these and other risk factors into account to assess an individual's overall risk of CVD, which can be reduced by taking drugs to reduce blood pressure or cholesterol levels (for example, pravastatin) and by making lifestyle changes.
Why Was This Study Done?
Inflammation (an immune response to injury) in the walls of blood vessels is thought to play a role in the development of atherosclerotic plaques. Consistent with this idea, several epidemiological studies (investigations of the causes and distribution of disease in populations) have shown that people with high circulating levels of markers of inflammation such as interleukin-6 (IL-6), C-reactive protein (CRP), and fibrinogen are more likely to have a stroke or a heart attack (a CVD event) than people with low levels of these markers. Although these studies have generally lumped together fatal and nonfatal CVD events, some evidence suggests that circulating inflammatory markers may be more strongly associated with fatal than with nonfatal CVD events. If this is the case, the mechanisms that lead to fatal and nonfatal CVD events may be subtly different and knowing about these differences could improve both the prevention and treatment of CVD. In this study, the researchers investigate this possibility using data collected in the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER; a trial that examined pravastatin's effect on CVD development among 70–82 year olds with pre-existing CVD or an increased risk of CVD because of smoking, high blood pressure, or diabetes).
What Did the Researchers Do and Find?
The researchers used several statistical models to examine the association between baseline levels of IL-6, CRP, and fibrinogen in the trial participants and nonfatal CVD events (nonfatal heart attacks and nonfatal strokes), fatal CVD events, death from other types of CVD, and deaths from other causes during 3.2 years of follow-up. Increased levels of all three inflammatory markers were more strongly associated with fatal CVD than with nonfatal CVD after adjustment for treatment allocation and for other established CVD risk factors but this pattern was strongest for IL-6. Thus, a unit increase in the log of IL-6 levels increased the risk of fatal CVD by half but increased the risk of nonfatal CVD by significantly less. The researchers also investigated whether including these inflammatory markers in tools designed to predict an individual's CVD risk could improve the tool's ability to distinguish between individuals with a high and low risk. The addition of IL-6 to established risk factors, they report, increased this discriminatory ability for fatal CVD but not for nonfatal CVD.
What Do These Findings Mean?
These findings indicate that, at least for the elderly at-risk patients who were included in PROSPER, inflammatory markers are more strongly associated with the risk of a fatal heart attack or stroke than with nonfatal CVD events. These findings need to be confirmed in younger populations and larger studies also need to be done to discover whether the same association holds when fatal heart attacks and fatal strokes are considered separately. Nevertheless, the present findings suggest that inflammation may specifically help to promote the development of serious, potentially fatal CVD and should stimulate improved research into the use of inflammation markers to predict risk of deaths from CVD.
Additional Information
Please access these Web sites via the online version of this summary at
The MedlinePlus Encyclopedia has pages on coronary heart disease, stroke, and atherosclerosis (in English and Spanish)
MedlinePlus provides links to many other sources of information on heart diseases, vascular diseases, and stroke (in English and Spanish)
Information for patients and caregivers is provided by the American Heart Association on all aspects of cardiovascular disease, including information on inflammation and heart disease
Information is available from the British Heart Foundation on heart disease and keeping the heart healthy
More information about PROSPER is available on the Web site of the Vascular Biochemistry Department of the University of Glasgow
PMCID: PMC2694359  PMID: 19554082
5.  Evaluating the buffering vs. direct effects hypotheses of emotional social support on inflammatory markers: The Multi-Ethnic Study of Atherosclerosis 
Brain, behavior, and immunity  2010;24(8):1294-1300.
Social support is associated with cardiovascular disease mortality, however the physiologic mechanisms underlying this relationship remains unspecified. This study evaluated the association of social support with inflammatory markers associated with cardiovascular risk: C-reactive protein (CRP), interleukin-6 (IL-6), and fibrinogen. We evaluated two competing models of the support-inflammation relationship: first, that low social support is directly associated with inflammation, and second, that high support acts to buffer the effect of stress on inflammation. Using data from the baseline interview of the Multi-Ethnic Study of Atherosclerosis (N = 6,814, 53% female, age 45–84 years) we assessed the independent and interacting associations of social support and stress with inflammation. Social support was measured by the Emotional Social Support Index. Stressors in multiple domains (work, family, finances, interpersonal) were assessed. Serum CRP, IL-6, and fibrinogen were analyzed from fasting samples using high-sensitivity assays. Multivariate linear regression, including models stratified by gender and age group (45 – 64 and 65 – 84 years), was used to assess the direct and buffering relationships between social support, stress, and inflammation. In bivariate analyses low social support was associated with higher levels of all three markers. In adjusted models, low support was associated with higher lnCRP (B: 0.15, 95% CI: 0.01, 0.30) among men but not women. High social support buffered the relationship between stress and CRP among middle-aged women only (P for interaction 0.042). Overall, social support was only modestly associated with inflammation in this relatively healthy sample, and these relationships varied by age and gender.
PMCID: PMC2949452  PMID: 20600815
social support; inflammation; aging; gender differences
6.  Inflammation and Reactivation of Latent Herpesviruses in Older Adults 
Brain, Behavior, and Immunity  2011;26(5):739-746.
Inflammation increases with age and is associated with many chronic diseases that are prevalent among older adults. Persistent pathogens such as latent herpesviruses and chronic bacterial infections can act as a source of inflammation. Herpesviruses, including Epstein-Barr virus (EBV) and cytomegalovirus (CMV), establish latent infections following primary infection and reactivate when the cellular immune system is compromised. EBV and CMV replication can induce proinflammatory cytokine production and thus could influence systemic inflammation. The present study addressed relationships among EBV and CMV antibody titers, and levels of C-reactive protein (CRP) and interleukin-6 (IL-6) in a sample of 222 community dwelling older adults (meanage= 64.1 ± 14.1 years). Participants were divided into two groups based on whether they were EBV seropositive and CMV seronegative (EBV+CMV−), or EBV and CMV seropositive (EBV+CMV+). Among individuals who were EBV+CMV−, EBV antibody titers were not associated with either CRP or IL-6 levels. However, among those who were EBV+CMV+, higher EBV antibody titers were related to elevated levels of CRP and IL-6 in those individuals with higher CMV antibody titers; there was no relationship between EBV antibody titers and CRP or IL-6 levels in those participants with lower CMV antibody titers. These data suggest that the combination of latent EBV and CMV reactivation (indexed by antibody titers) may boost CRP and IL-6 production. Thus, reactivation of multiple herpesviruses may drive inflammation and could contribute to poorer health among older adults.
PMCID: PMC3370109  PMID: 22155500
cytomegalovirus (CMV); Epstein-Barr virus (EBV); C-reactive protein (CRP); interleukin-6 (IL-6); aging; latent reactivation; immunosenescence
7.  Ectopic Lymphoid Structures Support Ongoing Production of Class-Switched Autoantibodies in Rheumatoid Synovium 
PLoS Medicine  2009;6(1):e1.
Follicular structures resembling germinal centres (GCs) that are characterized by follicular dendritic cell (FDC) networks have long been recognized in chronically inflamed tissues in autoimmune diseases, including the synovium of rheumatoid arthritis (RA). However, it is debated whether these ectopic structures promote autoimmunity and chronic inflammation driving the production of pathogenic autoantibodies. Anti-citrullinated protein/peptide antibodies (ACPA) are highly specific markers of RA, predict a poor prognosis, and have been suggested to be pathogenic. Therefore, the main study objectives were to determine whether ectopic lymphoid structures in RA synovium: (i) express activation-induced cytidine deaminase (AID), the enzyme required for somatic hypermutation and class-switch recombination (CSR) of Ig genes; (ii) support ongoing CSR and ACPA production; and (iii) remain functional in a RA/severe combined immunodeficiency (SCID) chimera model devoid of new immune cell influx into the synovium.
Methods and Findings
Using immunohistochemistry (IHC) and quantitative Taqman real-time PCR (QT-PCR) in synovial tissue from 55 patients with RA, we demonstrated that FDC+ structures invariably expressed AID with a distribution resembling secondary lymphoid organs. Further, AID+/CD21+ follicular structures were surrounded by ACPA+/CD138+ plasma cells, as demonstrated by immune reactivity to citrullinated fibrinogen. Moreover, we identified a novel subset of synovial AID+/CD20+ B cells outside GCs resembling interfollicular large B cells. In order to gain direct functional evidence that AID+ structures support CSR and in situ manufacturing of class-switched ACPA, 34 SCID mice were transplanted with RA synovium and humanely killed at 4 wk for harvesting of transplants and sera. Persistent expression of AID and Iγ-Cμ circular transcripts (identifying ongoing IgM-IgG class-switching) was observed in synovial grafts expressing FDCs/CD21L. Furthermore, synovial mRNA levels of AID were closely associated with circulating human IgG ACPA in mouse sera. Finally, the survival and proliferation of functional B cell niches was associated with persistent overexpression of genes regulating ectopic lymphoneogenesis.
Our demonstration that FDC+ follicular units invariably express AID and are surrounded by ACPA-producing plasma cells provides strong evidence that ectopic lymphoid structures in the RA synovium are functional and support autoantibody production. This concept is further confirmed by evidence of sustained AID expression, B cell proliferation, ongoing CSR, and production of human IgG ACPA from GC+ synovial tissue transplanted into SCID mice, independently of new B cell influx from the systemic circulation. These data identify AID as a potential therapeutic target in RA and suggest that survival of functional synovial B cell niches may profoundly influence chronic inflammation, autoimmunity, and response to B cell–depleting therapies.
Costantino Pitzalis and colleagues show that lymphoid structures in synovial tissue of patients with rheumatoid arthritis support production of anti-citrullinated peptide antibodies, which continues following transplantation into SCID mice.
Editors' Summary
More than 1 million people in the United States have rheumatoid arthritis, an “autoimmune” condition that affects the joints. Normally, the immune system provides protection against infection by responding to foreign antigens (molecules that are unique to invading organisms) while ignoring self-antigens present in the body's own tissues. In autoimmune diseases, this ability to discriminate between self and non-self fails for unknown reasons and the immune system begins to attack human tissues. In rheumatoid arthritis, the lining of the joints (the synovium) is attacked, it becomes inflamed and thickened, and chemicals are released that damage all the tissues in the joint. Eventually, the joint may become so scarred that movement is no longer possible. Rheumatoid arthritis usually starts in the small joints in the hands and feet, but larger joints and other tissues (including the heart and blood vessels) can be affected. Its symptoms, which tend to fluctuate, include early morning joint pain, swelling, and stiffness, and feeling generally unwell. Although the disease is not always easy to diagnose, the immune systems of many people with rheumatoid arthritis make “anti-citrullinated protein/peptide antibodies” (ACPA). These “autoantibodies” (which some experts believe can contribute to the joint damage in rheumatoid arthritis) recognize self-proteins that contain the unusual amino acid citrulline, and their detection on blood tests can help make the diagnosis. Although there is no cure for rheumatoid arthritis, the recently developed biologic drugs, often used together with the more traditional disease-modifying therapies, are able to halt its progression by specifically blocking the chemicals that cause joint damage. Painkillers and nonsteroidal anti-inflammatory drugs can reduce its symptoms, and badly damaged joints can sometimes be surgically replaced.
Why Was This Study Done?
Before scientists can develop a cure for rheumatoid arthritis, they need to know how and why autoantibodies are made that attack the joints in this common and disabling disease. B cells, the immune system cells that make antibodies, mature in structures known as “germinal centers” in the spleen and lymph nodes. In the germinal centers, immature B cells are exposed to antigens and undergo two genetic processes called “somatic hypermutation” and “class-switch recombination” that ensure that each B cell makes an antibody that sticks as tightly as possible to just one antigen. The B cells then multiply and enter the bloodstream where they help to deal with infections. Interestingly, the inflamed synovium of many patients with rheumatoid arthritis contains structures that resemble germinal centers. Could these ectopic (misplaced) lymphoid structures, which are characterized by networks of immune system cells called follicular dendritic cells (FDCs), promote autoimmunity and long-term inflammation by driving the production of autoantibodies within the joint itself? In this study, the researchers investigate this possibility.
What Did the Researchers Do and Find?
The researchers collected synovial tissue from 55 patients with rheumatoid arthritis and used two approaches, called immunohistochemistry and real-time PCR, to investigate whether FDC-containing structures in synovium expressed an enzyme called activation-induced cytidine deaminase (AID), which is needed for both somatic hypermutation and class-switch recombination. All the FDC-containing structures that the researchers found in their samples expressed AID. Furthermore, these AID-containing structures were surrounded by mature B cells making ACPAs. To test whether these B cells were derived from AID-expressing cells resident in the synovium rather than ACPA-expressing immune system cells coming into the synovium from elsewhere in the body, the researchers transplanted synovium from patients with rheumatoid arthritis under the skin of a special sort of mouse that largely lacks its own immune system. Four weeks later, the researchers found that the transplanted human lymphoid tissue was still making AID, that the level of AID expression correlated with the amount of human ACPA in the blood of the mice, and that the B cells in the transplant were proliferating.
What Do These Findings Mean?
These findings show that the ectopic lymphoid structures present in the synovium of some patients with rheumatoid arthritis are functional and are able to make ACPA. Because ACPA may be responsible for joint damage, the survival of these structures could, therefore, be involved in the development and progression of rheumatoid arthritis. More experiments are needed to confirm this idea, but these findings may explain why drugs that effectively clear B cells from the bloodstream do not always produce a marked clinical improvement in rheumatoid arthritis. Finally, they suggest that AID might provide a new target for the development of drugs to treat rheumatoid arthritis.
Additional Information.
Please access these Web sites via the online version of this summary at
This study is further discussed in a PLoS Medicine Perspective by Rene Toes and Tom Huizinga
The MedlinePlus Encyclopedia has a page on rheumatoid arthritis (in English and Spanish). MedlinePlus provides links to other information on rheumatoid arthritis (in English and Spanish)
The UK National Health Service Choices information service has detailed information on rheumatoid arthritis
The US National Institute of Arthritis and Musculoskeletal and Skin Diseases provides Fast Facts, an easy to read publication for the public, and a more detailed Handbook on rheumatoid arthritis
The US Centers for Disease Control and Prevention has an overview on rheumatoid arthritis that includes statistics about this disease and its impact on daily life
PMCID: PMC2621263  PMID: 19143467
8.  Individual pathogens, pathogen burden, and markers of subclinical atherosclerosis: the Multi-Ethnic Study of Atherosclerosis 
We examined the cross-sectional relationships of subclinical atherosclerosis – expressed by carotid intimal–medial thickness and coronary calcification – with antibodies to Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, herpes simplex virus, hepatitis A virus, and pathogen burden (number of positive pathogens). A random sample of 1056 individuals chosen from 5030 Multi-Ethnic Study of Atherosclerosis cohort participants were included. After multiple adjustment, no associations were found between atherosclerosis measures and either individual pathogens or pathogen burden. Interactions with inflammatory and endothelial function markers, demographic factors, BMI, high-density lipoprotein, diabetes, and smoking were also explored. The only interaction that was large, qualitative, statistically significant (P < 0.05) and in the expected direction was that between hepatitis A virus and soluble intercellular adhesion molecule-1 with regard to Agatston calcium score: the difference between hepatitis A virus-positive and hepatitis A virus-negative participants was −86 units in participants with soluble intercellular adhesion molecule-1 below the median, and +162 units in those with soluble intercellular adhesion molecule-1 equal or above the median. However, given the number of interactions that were explored, these results must be interpreted cautiously.
Findings from the present analyses do not provide support for an infectious etiology for subclinical atherosclerosis. However, the study’s limitations, which include its cross-sectional design and insufficient statistical power, suggest that inferences from its findings should be made cautiously.
PMCID: PMC2732746  PMID: 19444130
atherosclerosis; infections; pathogens
9.  Ectasia and Severe Atherosclerosis 
Texas Heart Institute Journal  2005;32(1):21-27.
To date, there has been no convincing evidence for an association between Chlamydia pneumoniae or Helicobacter pylori and ectasia. In this case-control study, we have investigated the association of H. pylori and C. pneumoniae seropositivity with ectasia, severe coronary atherosclerosis, and normal vessels, which were so classified by coronary angiography. We have also evaluated the influence of these infections on inflammatory markers such as high-sensitive C-reactive protein (hsCRP) and interleukin 6 (IL-6).
Of the 796 patients undergoing coronary angiography for suspected ischemic heart disease, 244 patients were recruited. Of these, 91 had normal vessels, 88 had 3 or more obstructed vessels, and 65 had ectatic vessels without atherosclerosis. Eighty-seven atherosclerotic patients (98.9%) were positive for C. pneumoniae IgG, as were 64 ectatic patients (98.5%) and 76 controls (83.5%) (P < 0.001). Forty-two atherosclerotic patients (47.7%) were positive for C. pneumoniae IgM, as were 43 ectatic patients (66.2%) and 43 controls (47.3%) (P = 0.036). Seventy-two atherosclerotic patients (81.8%) were positive for H. pylori IgA, as were 26 ectatic patients (40.0%) and 44 controls (48.4%) (P < 0.001). High-sensitive CRP levels were significantly higher in ectatic patients (5.639 mg/L) than in controls (4.390 mg/L) (P = 0.032), and IL-6 levels were significantly higher in atherosclerotic patients (33.92 U/L) than in controls (14.01 U/L) (P < 0.001). Interleukin-6 levels were higher in H. pylori seropositive patients, and hsCRP levels were higher in C. pneumoniae seropositive patients, when compared with seronegatives.
We suggest that, as in atherosclerosis, C. pneumoniae infection is related to ectasia, with raised CRP levels.
PMCID: PMC555817  PMID: 15902817
Atherosclerosis; bacterial infections/complications; biological markers; C-reactive protein; chlamydia infections/complications; Chlamydia pneumoniae; Cardiovascular diseases/etiology; dilatation, pathologic/etiology; helicobacter infections/complications; Helicobacter pylori; inflammation; interleukin-6
10.  The association of optimism and pessimism with inflammation and hemostasis in the Multi-Ethnic Study of Atherosclerosis (MESA) 
Psychosomatic medicine  2010;72(2):134-140.
Optimism and pessimism are associated with cardiovascular disease mortality and progression, however the biological mechanism remains unclear. This study investigates the association between optimism/pessimism and concentrations of seven inflammation and hemostasis markers.
This cross-sectional study used data from the Multi-Ethnic Study of Atherosclerosis (MESA), a study of 6814 persons aged 45–84 with no history of clinical cardiovascular disease. The Life-Orientation Test—Revised (LOT-R) was used to measure dispositional optimism and pessimism. Regression analyses were used to estimate associations of optimism and pessimism with interleukin-6 (IL-6), C-reactive protein (CRP), fibrinogen, homocysteine, factor VIII, D-dimer, and plasmin-antiplasmin, before and after adjustment for sociodemographics, depression, cynicism, health behaviors, BMI, hypertension, and diabetes.
Higher scores on the LOT-R (positive disposition) were related to lower concentrations of IL-6 (p=0.001), fibrinogen (p<0.001) and homocysteine (p=0.031). Associations were stronger for the pessimism subscale. After adjustment for demographics, the percentage differences in inflammatory markers corresponding to a 2-standard deviation increase in pessimism were 6.01% (p=0.001) for IL-6; 10.31% (p=0.001) for CRP; 2.47% (p<0.0001) for fibrinogen, and 1.36% (p=0.07) for homocysteine. Associations were attenuated but significant after adjustment for sociodemographics, depression, cynical distrust, and behaviors. Further adjustment for hypertension, BMI and diabetes reduced associations for CRP and IL-6. Pessimism remained associated with a 1.36% (p=0.02) increase in fibrinogen in the fully adjusted model. Factor VIII, D-dimer and plasmin-antiplasmin were not associated with the LOT-R or subscales.
Pessimism is related to higher levels of inflammation. Health behaviors, BMI, hypertension and diabetes appear to play a mediating role.
PMCID: PMC2842951  PMID: 20100888
Psychosocial factors; inflammation; coagulation; epidemiology; risk factors
11.  Elevated C-reactive protein levels are associated with postoperative events in patients undergoing lower extremity vein bypass surgery 
Journal of vascular surgery  2006;45(1):2-9.
Inflammatory markers such as high-sensitivity C-reactive protein (hsCRP) are associated with an increased risk of cardiovascular events and with the severity of peripheral arterial disease. The effects of inflammation on the development of vein graft disease remain speculative. We hypothesized that high levels of inflammatory markers would identify patients at increased risk for adverse events (graft failure, major cardiovascular events) after lower extremity bypass surgery.
Patients (n = 91) scheduled to undergo lower extremity bypass using autogenous vein were enrolled into a prospective study at two institutions. Exclusion criteria included the presence of major infection. A baseline plasma sample was obtained on the morning of lower extremity bypass. Biomarkers for inflammation included hsCRP, fibrinogen, and serum amyloid A (SAA). Values between patients with and without critical limb ischemia were compared. Proportions of events among dichotomized populations (upper limit of normal of each laboratory assay) were compared by log-rank test.
Of the patients undergoing lower extremity bypass, 69% were men, 53% were diabetic, 81% were smokers, and their mean ankle-brachial index was 0.51 ± 0.19. The indication for lower extremity bypass was critical limb ischemia in 55%. There were no perioperative deaths and two early graft occlusions. During a mean follow-up of 342 days (range, 36–694 days) there were four deaths, 27 graft-related events, and 10 other cardiovascular events. No relationships were found between events and demographics, comorbidities, baseline ankle-brachial index, or statin use. High-sensitivity CRP (P = .005), fibrinogen (P < .001), and SAA (P = .0001) levels were associated with critical limb ischemia at presentation. Among patients with an elevated hsCRP (>5 mg/L) immediately before surgery, major postoperative vascular events occurred in 60% (21/35), compared with a 32% (18/56) rate in those with a baseline CRP <5 mg/L (P = .004, log-rank test). On multivariable analysis, only elevated hsCRP correlated with adverse graft-related or cardiovascular events (P = .018).
The inflammatory biomarkers of hsCRP, fibrinogen, and SAA correlate with peripheral arterial disease severity at presentation in patients undergoing lower extremity bypass. Patients with elevated hsCRP are at increased risk for postoperative vascular events, most of which are related to the vein graft. These findings suggest a potential relationship between inflammation and outcomes after lower extremity vein bypass surgery.
PMCID: PMC3488442  PMID: 17123769
12.  Increased Carotid Intima-Media Thickness Associated with Antibody Responses to Varicella-Zoster Virus and Cytomegalovirus in HIV-Infected Patients 
PLoS ONE  2013;8(5):e64327.
We investigated the relationship of the Herpesviridiae with inflammation and subclinical atherosclerosis in HIV-infected patients.
Prospective study including virologically suppressed HIV-infected patients. IgG antibodies against herpesviruses, carotid intima-media thickness (cIMT), endothelial function through flow-mediated dilatation (FMD) of the brachial artery, and blood atherosclerosis biomarkers (hsCRP, TNF-α, IL-6, MCP-1, MDA, sCD14, sCD163, VCAM-1, ICAM-1, D-dimer, and PAI-1) were measured.
136 patients with HIV viral load <200 copies/ml were included. 93.4% patients were infected with herpes simplex virus type-1, 55.9% with herpes simplex virus type-2, 97.1% with varicella-zoster virus, 65.4% with human herpesvirus-6, 91.2% with cytomegalovirus, and 99.3% with Epstein-Barr virus. Previous AIDS diagnosis was associated with higher cytomegalovirus IgG titers (23,000 vs 17,000 AU, P = 0.011) and higher varicella-zoster virus IgG titers (3.19 vs 2.88 AU, P = 0.047), and there was a positive correlation of the Framingham risk score with IgG levels against cytomegalovirus (Spearman's Rho 0.216, P = 0.016) and Herpes simplex virus-2 (Spearman's Rho 0.293, P = 0.001). IgG antibodies against cytomegalovirus correlated in adjusted analysis with the cIMT (P = 0.030). High seropositivity for varicella-zoster virus (OR 2.91, 95% CI 1.05–8.01, P = 0.039), and for cytomegalovirus (OR 3.79, 95% CI 1.20–11.97, P = 0.023) were predictors for the highest quartile of the cIMT in adjusted analyses. PAI-1 levels were independently associated with cytomegalovirus IgG titers (P = 0.041), IL-6 and ICAM-1 levels with varicella-zoster virus IgG (P = 0.046 and P = 0.035 respectively), and hsCRP levels with Herpes simplex virus-2 IgG (P = 0.035).
In virologically suppressed HIV-infected patients, antibody responses against herpesviruses are associated with subclinical atherosclerosis, and with increased inflammation and coagulation biomarkers.
PMCID: PMC3662719  PMID: 23717597
13.  Lack of association between vascular dementia and Chlamydia pneumoniae infection: a case-control study 
BMC Neurology  2004;4:15.
Chronic inflammation appears to play a role in the pathogenesis of vascular dementia. Given the association between Chlamydia pneumoniae and stroke, the possibility exists that previous exposure to C. pneumoniae may play a role in vascular dementia. The objective of this study was to determine if there was an association between serological evidence of C. pneumoniae infection or inflammatory markers with vascular dementia.
28 case-patients with vascular dementia at a geriatric clinic and 24 caregiver-controls were tested for C. pneumoniae IgG and IgA antibodies. The association between vascular dementia and C. pneumoniae titres as well as inflammatory markers was estimated by using both conditional logistic regression and stratified logistic regression.
When matched cases were compared to controls, there was no significant difference in elevated C. pneumoniae specific IgG antibodies (titre ≥ 1:32), odds ratio [OR] 1.3 (95% confidence intervals [CI] 0.3 to 6.0), p = 0.71, or in elevated C. pneumoniae specific IgA antibodies (titre ≥ 1:16), OR 2.0 (95%CI 0.5 to 8.0), p = 0.33 indicative of past or persistent C. pneumoniae infection. Similarly, no difference in high IgG or IgA antibody levels (IgG titre ≥ 1:512 or IgA titre ≥ 1:64) between the two groups, indicative of recent C. pneumoniae infection, was found, OR 0.4 (95%CI 0.1 to 2.1), p = 0.27. For C-reactive protein (CRP), the mean difference between 18 matched pairs (case – control) was – 3.33 mg/L. There was no significant difference between cases and controls when comparing log transformed values, OR 0.03 (95%CI 0.00 to 2.89), p = 0.13 or comparing CRP values above or below the median, OR 0.8 (95%CI 0.2 to 3.4), p = 0.71. For fibrinogen, the mean difference between pairs (case – control) was -0.07 g/L. There was no statistical difference between cases and controls when comparing log transformed values, OR 0.6 (95%CI 0.0 to 31.2), p = 0.79 or between fibrinogen values above and below the median, OR = 0.5 (95%CI 0.1 to 2.0), p = 0.50.
We found no evidence for a significant association between C. pneumoniae infection, inflammatory markers such as CRP and fibrinogen, and vascular dementia.
PMCID: PMC524508  PMID: 15476562
14.  Relationship between CRP and hypofibrinolysis: Is this a possible mechanism to explain the association between CRP and outcome in critically ill patients? 
Thrombosis Journal  2004;2:7.
Endothelial cell dysfunction may be implicated in the development of multiple organ failure (MOF) by a number of mechanisms. Among these, altered fibrinolysis promotes fibrin deposition, which may create microvascular alterations during inflammation. Elevated concentrations of C-reactive protein (CRP), especially when these persist over time, are correlated with an increased risk of MOF and death. CRP may inhibit fibrinolysis by inducing plasminogen activator inhibitor-1 (PAI-1) release from human aortic endothelial cells. Moreover, the administration of recombinant CRP in volunteers may increase circulating PAI-1 levels.
In this study, we tested the hypothesis that CRP is associated with hypofibrinolysis in intensive care patients with and without sepsis.
We studied the association of inflammation and abnormal fibrinolysis in intensive care unit (ICU) patients with (n = 11) and without (n = 21) sepsis. The inflammatory response was assessed by serum concentration of C-reactive protein (CRP), a marker of the acute phase reaction, which increase rapidly in the inflammatory response, and the plasma fibrinolytic capacity was evaluated by the Euglobulin Clot Lysis Time (ECLT), determined by a new semi-automatic method.
ECLT was significantly higher in septic than non-septic patients (1104 ± 439 vs 665 ± 275 min; p = 0.002) and was significantly correlated with CRP concentration (R2 = 0.45; p < 0.001). In a multivariate analysis, CRP was the strongest predictor of ECLT (R2 = 0.51, F = 25.6, p < 0.001). In addition, the overall ICU length of stay was significantly correlated with CRP (R2 = 0.264, p = 0.003) and ECLT (R2 = 0.259, p = 0.003).
In critically ill patients a significant correlation thus exists between plasma fibrinolytic capacity and serum CRP levels. Our data were obtained in the first 24 hours of ICU admission or of sepsis, thus, the relation between CRP and hypofibrinolysis appeared very quickly. This finding is compatible with a link between inflammation and abnormal fibrinolysis, and may explain the negative prognostic value of CRP in critically ill patients.
PMCID: PMC524363  PMID: 15456513
C-reactive protein; acute phase reactant; euglobulin clot lysis time; inflammation; sepsis; endothelium dysfunction.
15.  Association Between Resting Heart Rate and Inflammatory Biomarkers (High-Sensitivity C-Reactive Protein, Interleukin-6, and Fibrinogen) (from the Multi-Ethnic Study of Atherosclerosis) 
The American journal of cardiology  2013;113(4):644-649.
Heart rate (HR) at rest is associated with adverse cardiovascular events; however, the biologic mechanism for the relation is unclear. We hypothesized a strong association between HR at rest and subclinical inflammation, given their common interrelation with the autonomic nervous system. HR at rest was recorded at baseline in the Multi-Ethnic Study of Atherosclerosis, a cohort of 4 racial or ethnic groups without cardiovascular disease at baseline and then divided into quintiles. Subclinical inflammation was measured using high-sensitivity C-reactive protein, interleukin-6, and fibrinogen. We used progressively adjusted regression models with terms for physical activity and atrioventricular nodal blocking agents in the fully adjusted models. We examined inflammatory markers as both continuous and categorical variables using the clinical cut point of ≥3 mg/L for high-sensitivity C-reactive protein and the upper quartiles of fibrinogen (≥389 mg/dl) and interleukin-6 (≥1.89 pg/ml). Participants had a mean age of 62 years (SD 9.7), mean resting heart rate of 63 beats/min (SD 9.6) and were 47% men. Increased HR at rest was significantly associated with higher levels of all 3 inflammatory markers in both continuous (p for trend <0.001) and categorical (p for trend <0.001) models. Results were similar among all 3 inflammatory markers, and there was no significant difference in the association among the 4 racial or ethnic groups. In conclusion, an increased HR at rest was associated with a higher level of inflammation among an ethnically diverse group of subjects without known cardiovascular disease.
PMCID: PMC4280910  PMID: 24393259
16.  Impact of seropositivity to Chlamydia pneumoniae and anti-hHSP60 on cardiovascular events in hemodialysis patients 
Cell Stress & Chaperones  2010;16(2):219-224.
Autoimmunity to heat shock protein 60 (HSP60) has been related to atherosclerosis. Chlamydia pneumoniae (CP), the most studied infectious agent implicated in promoting atherosclerosis, produces a form of HSP60, which can induce an autoimmune response, due to high antigenic homology with human HSP60 (hHSP60). In this study, we evaluated the correlations among anti-hHSP60 antibodies, CP infection, and cardiovascular disease (CVD) in a high-risk population, such as patients undergoing hemodialysis (HD). Thirty-two patients (67.9 ± 13.9 years; male/female, 23:9) on regular HD were enrolled. Global absolute cardiovascular risk (GCR) was assessed using the Italian CUORE Project’s risk charts, which evaluate age, gender, smoking habits, diabetes, systolic blood pressure, and serum cholesterol. The occurrence of cardiovascular events during a 24-month follow-up was recorded. Seropositivity to CP and the presence of anti-hHSP60 antibodies were tested by specific enzyme-linked immunosorbent assays. Inflammation was assessed by measurement of C-reactive protein (CRP) serum levels. Fifteen healthy sex and age-matched (61.9 ± 9.5 years; male/female, 11:4) subjects were the control group. Fifteen of 32 patients resulted seropositive for CP. CP + patients were older than CP−, while they did not differ for GCR, CRP, and dialytic parameters. CVD incidence was significantly higher in CP+ (9 CP+ vs 2 CP−, p < 0.05). Cox analysis recognized that the incidence of CVD was independently correlated with seropositivity to CP (HR, 7.59; p = 0.01; 95% CI = 1.63–35.4). On the other hand, there were no significant differences in anti-hHSP60 levels among CP+, CP− and healthy subjects: 18.11 μg/mL (14.8–47.8), 31.4 μg/mL (23.2–75.3), and 24.72 μg/mL (17.7–41.1), respectively. Anti-hHSP60 did not correlate to GCR, CRP, and incidence of CVD. In conclusion, our data suggest that anti-hHSP60 autoimmune response is not related to CP infection and CP-related CVD risk in HD patients.
PMCID: PMC3059795  PMID: 20922511
HSP60; Anti-human HSP60; Chlamydia pneumoniae; Cardiovascular risk; Hemodialysis
17.  Comparison of inflammation, arterial stiffness and traditional cardiovascular risk factors between rheumatoid arthritis and inflammatory bowel disease 
Inflammation plays an important role in the pathogenesis of atherosclerosis. The link between rheumatoid arthritis (RA) and an increased risk of cardiovascular disease and mortality is well established; however, the association between inflammatory bowel disease (IBD) and cardiovascular risk is controversial. Arterial stiffness is both a marker and risk factor for atherosclerosis. Here we aimed to 1) compare circulating markers of inflammation and endothelial dysfunction, traditional cardiovascular risk factors, and arterial stiffness between RA and IBD to help to understand their different associations with cardiovascular disease; 2) assess the impacts of circulating markers of inflammation and endothelial dysfunction, and traditional risk factors on arterial stiffness.
Patients with RA (n = 43) and IBD (n = 42), and control subjects (n = 73) were recruited. Plasma inflammatory markers and von Willebrand factor (vWF) were measured by Multiplex assays or ELISA. Arterial stiffness was determined by brachial-ankle pulse wave velocity (baPWV) and ankle-brachial index (ABI) was measured. Framingham Risk Score (FRS) was calculated, and other traditional risk factors were also documented.
Plasma levels of several inflammatory markers and vWF were significantly but comparably elevated in RA and IBD compared with controls, except for a higher level of C-reactive protein (CRP) in RA than IBD. Compared to controls, FRS, body mass index, waist circumference, and triglycerides were increased in RA, but not in IBD. baPWV did not significantly differ among 3 groups, while ABI was modestly but significantly lower in IBD than controls. Circulating markers (macrophage migration inhibitory factor, tumour necrosis factor-α, CRP, and vWF) were significantly associated with baPWV. However, traditional risk factors (age, systolic blood pressure, body mass index, diabetes and triglycerides) were the parameters associated with baPWV in multiple regression analyses (overall r = 0.866, p < 0.001).
RA has a higher level of CRP and more pronounced traditional cardiovascular risk factors than IBD, which may contribute to the difference in their associations with cardiovascular disease and mortality. Traditional risk factors, rather than inflammation markers, are major predictors of arterial stiffness even in subjects with inflammatory disorders. Our results point to the importance of modifying traditional risk factors in patients with inflammatory disorders.
PMCID: PMC4203921  PMID: 25337037
Inflammation; Rheumatoid arthritis; Inflammatory bowel disease; Arterial stiffness; Pulse wave velocity
18.  JC virus antibody index in natalizumab-treated patients: correlations with John Cunningham virus DNA and C-reactive protein level 
Natalizumab-treated patients have a higher risk of developing progressive multifocal leukoencephalopathy. Exposure to John Cunningham virus (JCV) is a prerequisite for PML (progressive multifocal leukoencephalopathy). To assess JCV exposure in multiple sclerosis patients, we performed a serological examination, obtained the antibody index, performed real-time polymerase chain reaction (PCR) to detect JCV DNA in plasma and urine, and investigated the role of ultrasensitive C-reactive protein (usCRP) as a possible biological marker of JCV reactivation. We retrospectively analyzed consecutive natalizumab-treated multiple sclerosis patients who underwent a JCV antibody test through a two-step enzyme-linked immunosorbent assay (STRATIFY test) to the measure of serum usCRP levels, and to perform blood and urine JCV PCR. The studied cohort included 97 relapsing–remitting patients (60 women). Fifty-two patients (53.6%) tested positive for anti-JCV antibodies. PCR showed JCV DNA in the urine of 30 out of 83 (36.1%) patients and 28 out of 44 seropositive patients (63.6%), with a 6.7% false-negative rate for the STRATIFY test. Normalized optical density values were higher in urinary JCV DNA-positive patients (P<0.0001). Interestingly, the level of usCRP was higher in urinary JCV DNA-positive patients and correlated to the number of DNA copies in urine (P=0.028). As expected, patients’ age correlated with JCV seropositivity and with JC viruria (P=0.02 and P=0.001, respectively). JC viruria was significantly correlated with a high JCV antibody index and high serum usCRP levels. We suggest that PCR and usCRP might be useful as markers of JCV reactivation, and that patients should be monitored between STRATIFY assessments.
PMCID: PMC4199559  PMID: 25328396
multiple sclerosis; John Cunningham virus; natalizumab; antibodies; polymerase chain reaction; ultrasensitive C-reactive protein
19.  Inflammation, Insulin Resistance, and Diabetes—Mendelian Randomization Using CRP Haplotypes Points Upstream 
PLoS Medicine  2008;5(8):e155.
Raised C-reactive protein (CRP) is a risk factor for type 2 diabetes. According to the Mendelian randomization method, the association is likely to be causal if genetic variants that affect CRP level are associated with markers of diabetes development and diabetes. Our objective was to examine the nature of the association between CRP phenotype and diabetes development using CRP haplotypes as instrumental variables.
Methods and Findings
We genotyped three tagging SNPs (CRP + 2302G > A; CRP + 1444T > C; CRP + 4899T > G) in the CRP gene and measured serum CRP in 5,274 men and women at mean ages 49 and 61 y (Whitehall II Study). Homeostasis model assessment-insulin resistance (HOMA-IR) and hemoglobin A1c (HbA1c) were measured at age 61 y. Diabetes was ascertained by glucose tolerance test and self-report. Common major haplotypes were strongly associated with serum CRP levels, but unrelated to obesity, blood pressure, and socioeconomic position, which may confound the association between CRP and diabetes risk. Serum CRP was associated with these potential confounding factors. After adjustment for age and sex, baseline serum CRP was associated with incident diabetes (hazard ratio = 1.39 [95% confidence interval 1.29–1.51], HOMA-IR, and HbA1c, but the associations were considerably attenuated on adjustment for potential confounding factors. In contrast, CRP haplotypes were not associated with HOMA-IR or HbA1c (p = 0.52–0.92). The associations of CRP with HOMA-IR and HbA1c were all null when examined using instrumental variables analysis, with genetic variants as the instrument for serum CRP. Instrumental variables estimates differed from the directly observed associations (p = 0.007–0.11). Pooled analysis of CRP haplotypes and diabetes in Whitehall II and Northwick Park Heart Study II produced null findings (p = 0.25–0.88). Analyses based on the Wellcome Trust Case Control Consortium (1,923 diabetes cases, 2,932 controls) using three SNPs in tight linkage disequilibrium with our tagging SNPs also demonstrated null associations.
Observed associations between serum CRP and insulin resistance, glycemia, and diabetes are likely to be noncausal. Inflammation may play a causal role via upstream effectors rather than the downstream marker CRP.
Using a Mendelian randomization approach, Eric Brunner and colleagues show that the associations between serum C-reactive protein and insulin resistance, glycemia, and diabetes are likely to be noncausal.
Editors' Summary
Diabetes—a common, long-term (chronic) disease that causes heart, kidney, nerve, and eye problems and shortens life expectancy—is characterized by high levels of sugar (glucose) in the blood. In people without diabetes, blood sugar levels are controlled by the hormone insulin. Insulin is released by the pancreas after eating and “instructs” insulin-responsive muscle and fat cells to take up the glucose from the bloodstream that is produced by the digestion of food. In the early stages of type 2 diabetes (the commonest type of diabetes), the muscle and fat cells become nonresponsive to insulin (a condition called insulin resistance), and blood sugar levels increase. The pancreas responds by making more insulin—people with insulin resistance have high blood levels of both insulin and glucose. Eventually, however, the insulin-producing cells in the pancreas start to malfunction, insulin secretion decreases, and frank diabetes develops.
Why Was This Study Done?
Globally, about 200 million people have diabetes, but experts believe this number will double by 2030. Ways to prevent or delay the onset of diabetes are, therefore, urgently needed. One major risk factor for insulin resistance and diabetes is being overweight. According to one theory, increased body fat causes mild, chronic tissue inflammation, which leads to insulin resistance. Consistent with this idea, people with higher than normal amounts of the inflammatory protein C-reactive protein (CRP) in their blood have a high risk of developing diabetes. If inflammation does cause diabetes, then drugs that inhibit CRP might prevent diabetes. However, simply measuring CRP and determining whether the people with high levels develop diabetes cannot prove that CRP causes diabetes. Those people with high blood levels of CRP might have other unknown factors in common (confounding factors) that are the real causes of diabetes. In this study, the researchers use “Mendelian randomization” to examine whether increased blood CRP causes diabetes. Some variants of CRP (the gene that encodes CRP) increase the amount of CRP in the blood. Because these variants are inherited randomly, there is no likelihood of confounding factors, and an association between these variants and the development of insulin resistance and diabetes indicates, therefore, that increased CRP levels cause diabetes.
What Did the Researchers Do and Find?
The researchers measured blood CRP levels in more than 5,000 people enrolled in the Whitehall II study, which is investigating factors that affect disease development. They also used the “homeostasis model assessment-insulin resistance” (HOMA-IR) method to estimate insulin sensitivity from blood glucose and insulin measurements, and measured levels of hemoglobin A1c (HbA1c, hemoglobin with sugar attached—a measure of long-term blood sugar control) in these people. Finally, they looked at three “single polynucleotide polymorphisms” (SNPs, single nucleotide changes in a gene's DNA sequence; combinations of SNPs that are inherited as a block are called haplotypes) in CRP in each study participant. Common haplotypes of CRP were related to blood serum CRP levels and, as previously reported, increased blood CRP levels were associated with diabetes and with HOMA-IR and HbA1c values indicative of insulin resistance and poor blood sugar control, respectively. By contrast, CRP haplotypes were not related to HOMA-IR or HbA1c values. Similarly, pooled analysis of CRP haplotypes and diabetes in Whitehall II and another large study on health determinants (the Northwick Park Heart Study II) showed no association between CRP variants and diabetes risk. Finally, data from the Wellcome Trust Case Control Consortium also showed no association between CRP haplotypes and diabetes risk.
What Do These Findings Mean?
Together, these findings suggest that increased blood CRP levels are not responsible for the development of insulin resistance or diabetes, at least in European populations. It may be that there is a causal relationship between CRP levels and diabetes risk in other ethnic populations—further Mendelian randomization studies are needed to discover whether this is the case. For now, though, these findings suggest that drugs targeted against CRP are unlikely to prevent or delay the onset of diabetes. However, they do not discount the possibility that proteins involved earlier in the inflammatory process might cause diabetes and might thus represent good drug targets for diabetes prevention.
Additional Information.
Please access these Web sites via the online version of this summary at
This study is further discussed in a PLoS Medicine Perspective by Bernard Keavney
The MedlinePlus encyclopedia provides information about diabetes and about C-reactive protein (in English and Spanish)
US National Institute of Diabetes and Digestive and Kidney Diseases provides patient information on all aspects of diabetes, including information on insulin resistance (in English and Spanish)
The International Diabetes Federation provides information about diabetes, including information on the global diabetes epidemic
The US Centers for Disease Control and Prevention provides information for the public and professionals on all aspects of diabetes (in English and Spanish)
Wikipedia has a page on Mendelian randomization (note: Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
PMCID: PMC2504484  PMID: 18700811
20.  Association between dietary fiber and markers of systemic inflammation in the Women’s Heath Initiative Observational Study 
Systemic inflammation may play an important role in the development of atherosclerosis, type 2 diabetes, and some cancers. Few studies have comprehensively assessed the direct relationships between dietary fiber and inflammatory cytokines, especially in minority populations. Using baseline data from 1,958 postmenopausal women enrolled in the Women’s Heath Initiative Observational Study, we examined cross-sectional associations between dietary fiber intake and markers of systemic inflammation (including serum C-reactive protein (hs-CRP), interleukin 6 (IL-6), and tumor necrosis factor α receptor 2 (TNF-α-R2)), as well as differences in these associations by ethnicity.
Multiple linear regression models were used to assess the relationship between fiber intake and makers of systemic inflammation.
After adjustment for covariates, intake of dietary fiber were inversely associated with both IL-6 (P values for trend were 0.01 for total fiber, 0.004 for soluble fiber, and 0.001 for insoluble fiber) and TNF-α-R2 (P values for trend were 0.002 for total, 0.02 for soluble, and <0.001 for insoluble fiber). Although the sample sizes were small in minority Americans, results were generally consistent with that found among European-Americans. We did not observe any significant association between intake of dietary fiber and hs-CRP.
These findings lend support to the hypothesis that a high-fiber diet is associated with lower plasma levels of IL-6 and TNF-α-R2. Contrary to previous reports, however, there was no association between fiber and hs-CRP among postmenopausal women. Future studies on the influence of diet on inflammation should include IL-6 and TNF-α-R2 and enroll participants from ethnic minorities.
PMCID: PMC2603616  PMID: 18562168
dietary fiber; C-reactive protein; interleukin-6; tumor necrosis factor-alpha receptor 2; inflammation; cytokines; epidemiology; cardiovascular disease; nutrition
21.  Differences of Circulating Inflammatory Markers between Large- and Small Vessel Disease in Patients with Acute Ischemic Stroke 
Background: The difference of inflammatory response between the pathogenesis of cerebral large- and small vessel disease after stroke remains unclear. In present study, we aim to determine the association of circulating inflammatory markers with different stroke subtype.
Methods: 99 patients with non-cardioembolic stroke were divided into large artery atherosclerosis (LAA) and small-artery occlusion (SAO) according to TOAST classification. A panel of plasma inflammatory markers including leukocyte, lymphocyte, CRP, fibrinogen, D-dimer, CD40L, IFN-γ, IL-1α, IL-1β, IL-6, IL-8, IL-17 and TNF-α were measured within 72 hours following cerebral ischemia. The relation of their levels in plasma with stroke subtype was further studied. All statistical data analysis was performed by SPSS 17.0 software.
Results: We found that only CRP were closely associated with stroke subtype (p<0.05). Compared to SAO subgroup, the plasma levels of CRP was higher in LAA subgroup (p<0.05). The predictive efficiency of CRP more than 3.2 for LAA was 85.7% sensitivity. The influencing factor of CRP includes IL-6, lymphocyte, fibrinogen and D-dimer.
Conclusion: LAA had a stronger activation of inflammation than SAO in the pathogenesis, which was associated with the changes of CRP.
PMCID: PMC3753418  PMID: 23983602
CRP; Cytokine; Inflammation; Stroke subtype
22.  Impaired Arterial Stiffness in Systemic Lupus Ertythematosus - Correlations with Inflammation Markers 
Background: Systemic lupus erythematosus (SLE) is an inflammatory disease caused by autoimmune dysregulation, which mainly affects young women, usually free from atherosclerosis. Accelerated atherosclerosis is a well established complication of SLE and it cannot be explained by Framingham risk factors alone, and has been attributed to complex interactions between traditional risk factors and factors associated with the disease per se, or its treatment. Arterial stiffness and endothelium function may serve as a valuable measure to be counted in the follow-up of these patients prior to a potential cardiovascular event. The aim of the study was to evaluate atherosclerosis, inflammatory process, immune mediated, using imaging techniques and to identify the role of molecules known to be involved in inflammation, hsCRP, homocysteine, IL-6, ESR and fibrinogen, in the development and perpetuation of atherosclerosis in patients with systemic lupus erythematosus. Methods Our prospective study included 53 patients diagnosed with systemic lupus erythematosus and fulfilled the revised ACR (American College of Rheumatology) criteria for the classification of SLE. Exclusion criteria were <18 years of age, history of CVD, infections, diabetes mellitus, dyslipidemia. Results: We enrolled 53 patients with SLE, 50 (94%) women and 3 (6%) men, with a mean age of 31,92 years (SD 5,55; limits 22-44) with no significant difference between sex (31,65±3,4 years in women and 37,33±4,05 years in men). The measurement of inflammation markers revealed increased values for all the variables: ESR had a mean value of 69,19± 14,18mm, fibrinogen 445,66 ±4,56mg%; IL-6 had a mean value of 11,209 ±1,56pg/ml; homocysteine 17,721±2,5374 µmol/l and for hs CRP the mean value was 3,493±1,12 mg/l. The assesement of arterial stiffness showed a mean value of 23,32% (SD 5,82; 95%CI 21,716 - 24,925) for AIx and 9,1m/s (SD 0,49; 95%CI 8,971 - 9,244) for cfPWV. There was a positive, significant correlation between AIx and hsCRP (r=0,612; 95%CI 0,4104 - 0,7576; p<0,001), (r=0,526; 95% CI 0,2979 to 0,6971; p=0,0001), for AIx and homocysteine (r=0,526; 95%CI 0,2979 to 0,6971; p=0,0001). The correlation coefficient with AIx was similar for ESR and fibrinogen (r=0,63 and 0,60). IL-6 and AIx correlated correlated positively, (r=0,369; 95%CI 0,1097 - 0,5813), statistically significant (p=0,006), but the correlation was not powerful. hsCRP and cfPWV were related (r=0,652; 95%CI 0,4677-0,7862; p<0,001); cfPWV also correlated with IL-6 (r=0,6552; 95%CI 0,4677- 0,7862; p<0,0001), homocysteine (r=0,9174; 95%CI 0,8606- 0,9517; p<0,0001), ESR (r=0,74) and fibrinogen (r=0,64). Conclusions: In summary, our data suggest that arterial stiffness is related to the level of systemic inflammation, and that inflammation is involved in the early alteration of arterial wall. Increase in arterial stiffness can be detected by applanation tonometry, and may serve as an important predictor of future cardiovascular events, since an early diagnosis may have a significant value in preventing the development of major vascular disease.
PMCID: PMC3994677  PMID: 24778842
systemic lupus erythematosus; inflammation markers; augmentation index; pulse wave velocity
23.  Reactivation of Herpes Simplex Virus Type 1 is Associated with Cytomegalovirus and Age 
Journal of medical virology  2012;84(11):1797-1802.
Recent studies have shown that Cytomegalovirus (CMV) may be an emerging marker of immunosenescence. CMV can affect the immune system by directly infecting leukocytes and hematopoietic cells or by eliciting an expansion of oligoclonal CD8+ T cells/contraction of the naïve T cell compartment that may reduce the host’s ability to fight other pathogens. To investigate further CMV-associated changes in immunity, a study was conducted with 1,454 adults (ages 25–91) to determine the association between CMV and reactivation of another latent herpesvirus, Herpes simplex virus type 1 (HSV-1), as indexed by antibody titers. Elevated antibody titers to latent HSV-1 were significantly associated with both CMV seropositivity and high CMV antibody levels. Evaluation by specific age groups (<45, 45–64, and 65+ years old) revealed that this association was detectable early in life (<45 years of age). Increases in HSV-1 antibodies by age occurred in CMV seropositive individuals but not CMV seronegative subjects. Within CMV seropositive subjects, increases in HSV-1 antibodies by age were only found in individuals with low CMV antibody levels as those with high CMV antibodies already exhibited elevated HSV-1 antibodies. These associations remained significant after accounting for body mass index, gender, and socioeconomic status. These results suggest that CMV can influence the immune response to another pathogen and support the concept that CMV may accelerate immunosenescence.
PMCID: PMC3463941  PMID: 22997083
herpesvirus; Herpes simplex virus (HSV-1); Cytomegalovirus (CMV); aging; immunosenescence
24.  Clinical Features and Serum Biomarkers in HIV Immune Reconstitution Inflammatory Syndrome after Cryptococcal Meningitis: A Prospective Cohort Study 
PLoS Medicine  2010;7(12):e1000384.
David Boulware and colleagues investigate clinical features in a prospective cohort with AIDS and recent cryptococcal meningitis after initiation of antiretroviral therapy to identify biomarkers for prediction and diagnosis of CM-IRIS (cryptococcal meninigitis-related immune reconstitution inflammatory syndrome).
Although antiretroviral therapy (ART) improves survival in persons with cryptococcal meningitis (CM) and AIDS, ART frequently elicits HIV immune reconstitution inflammatory syndrome (IRIS), an exaggerated and frequently deadly inflammatory reaction that complicates recovery from immunodeficiency. The pathogenesis of IRIS is poorly understood and prediction of IRIS is not possible.
Methods and Findings
We prospectively followed 101 ART-naïve Ugandans with AIDS and recent CM for one year after initiating ART, and used Luminex multiplex assays to compare serum cytokine levels in participants who did or did not develop IRIS. IRIS occurred in 45% of participants with recent CM on ART, including 30% with central nervous system (CNS) manifestations. The median time to CM-IRIS was 8.8 wk on ART. Overall mortality on ART was 36% with IRIS and 21% without IRIS. CM-IRIS was independently associated with death (HR = 2.3, 95% CI 1.1–5.1, p = 0.04). Patients experiencing subsequent CM-IRIS had 4-fold higher median serum cryptococcal antigen (CRAG) levels pre-ART (p = 0.006). Higher pre-ART levels of interleukin (IL)-4 and IL-17 as well as lower tumor necrosis factor (TNF)-α, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and vascular endothelial growth factor (VEGF) predicted future IRIS in multivariate analyses (area under the curve [AUC] = 0.82). An algorithm based on seven pre-ART serum biomarkers was a robust tool for stratifying high (83%), moderate (48%), and low risk (23%) for IRIS in the cohort. After ART was initiated, increasing levels of C-reactive protein (CRP), D-dimer, IL-6, IL-7, IL-13, G-CSF, or IL-1RA were associated with increasing hazard of IRIS by time-to-event analysis (each p≤0.001). At the time of IRIS onset, multiple proinflammatory cytokine responses were present, including CRP and IL-6. Mortality was predicted by pre-ART increasing IL-17, decreasing GM-CSF, and CRP level >32 mg/l (highest quartile). Pre-ART CRP level >32 mg/l alone was associated with future death (OR = 8.3, 95% CI 2.7–25.6, p<0.001).
Pre-ART increases in Th17 and Th2 responses (e.g., IL-17, IL-4) and lack of proinflammatory cytokine responses (e.g., TNF-α, G-CSF, GM-CSF, VEGF) predispose individuals to subsequent IRIS, perhaps as biomarkers of immune dysfunction and poor initial clearance of CRAG. Although requiring validation, these biomarkers might be an objective tool to stratify the risk of CM-IRIS and death, and could be used clinically to guide when to start ART or use prophylactic interventions.
Please see later in the article for the Editors' Summary
Editors' Summary
Since 1981, AIDS has killed more than 25 million people and about 33 million people are now infected with HIV, which causes AIDS. HIV, which is most often transmitted through unprotected sex with an HIV-infected partner, infects and kills immune system cells. Eventually, the immune system becomes so weak that unusual infections begin to occur. These “opportunistic” infections are infections that take advantage of the opportunity offered by a weakened immune system. One common and deadly opportunistic infection in people affected by AIDS is cryptococcal meningitis (CM), an infection around the brain that is caused by the fungus Cryptococcus neoformans. About one million cases of CM occur every year. CM can be treated with a drug called amphotericin but usually recurs unless another drug called fluconazole is taken daily thereafter. HIV therapy is lifesaving by suppressing the HIV virus and allowing immune system recovery. This immune recovery also helps to prevent the recurrence of CM.
Why Was This Study Done?
Unfortunately, HIV therapy can also elicit a serious condition called immune reconstitution inflammatory syndrome (IRIS) in people with CM and AIDS. IRIS is an exaggerated inflammatory immune response that kills up to one-third of affected people. Inflammation, which is characterized by swelling and redness, is the body's first defense against infection, but uncontrolled inflammation causes widespread tissue damage. Experts think that CM-IRIS may be the result of an unbalanced recovery of the immune system leading to an inappropriate immune response to persisting C. neoformans fragments and proteins that are slowly cleared from the body over months. Unfortunately, it is impossible to predict which individuals with CM and AIDS will develop IRIS when they are given HIV therapy. In this prospective study, the researchers investigated clinical features and cytokine profiles in a group of Ugandans with AIDS and recent CM for one year after starting HIV therapy to identify biomarkers that could be used to predict and diagnose CM-IRIS. Cytokines are proteins secreted by immune system cells that regulate the immune response; biomarkers are proteins found in the blood that indicate specific diseases.
What Did the Researchers Do and Find?
The researchers enrolled 101 Ugandans with AIDS and recent CM who had not previously received HIV therapy. They compared cytokine patterns in individuals who did and did not subsequently develop IRIS after starting HIV therapy. Overall, 45% of the patients developed IRIS. Deaths occurred in 36% of the patients who developed IRIS and in 21% of those who did not develop IRIS. Patients who developed CM-IRIS after starting HIV therapy had 4-fold higher baseline concentrations of cryptococcal antigen in their blood than patients who did not develop CM-IRIS. Prior to starting HIV therapy, higher levels of the cytokines IL-4 and IL-17 and lower levels of four cytokines—TNF-α, G-CSF, GM-CSF, and VEGF—predicted IRIS development, and an algorithm (formula) based on the baseline levels of seven serum biomarkers was able to group the patients into high, moderate, and low risk of IRIS. After starting HIV therapy, increasing levels of the inflammatory proteins C-reactive protein and D-dimer, and of several cytokines, were associated with an increased risk of IRIS. At the time of IRIS onset, the levels of many proinflammatory cytokine increased. Biomarkers also predicted death after starting HIV therapy with increasing levels of IL-17, decreasing levels of GM-CSF, and a C-reactive protein level of more than 32 mg/l (four times higher than normal) predicted death within one year.
What Do These Findings Mean?
These findings support the hypothesis that some AIDS patients who have a very damaged immune system have a very poor initial immune response and poor clearance of cryptococcus, which predisposes them to IRIS. The findings also identify three distinct phases of IRIS development. Before HIV therapy, a very damaged immune system with a lack of inflammatory responses to infection or inappropriate responses leads to ineffective clearance of the organism and its antigens. After HIV therapy is started, the presence of copious antigens promotes proinflammatory signaling to the immune system. As the immune system recovers proinflammatory immune cells are promoted. Finally, at the time of IRIS, a generalized “cytokine storm” occurs, which is potentially fatal when this inflammation occurs in the brain. The biomarkers identified here as indicators of a predisposition to IRIS need to be validated in more patients in more countries before they can be used as a clinical tool for predicting the risk of IRIS. If they are validated, they could help clinicians decide when to start HIV therapy in patients with AIDS and recent CM, and could guide the use of therapies that could help prevent the abnormal inflammatory responses.
Additional Information
Please access these websites via the online version of this summary at
The US National Institute of Allergy and Infectious Diseases provides information on HIV infection and AIDS
HIV InSite has information on all aspects of HIV/AIDS, including Knowledge Base Chapters on cryptococcosis and HIV and on the clinical implications of IRIS
Information is available from Avert, an international AIDS charity on all aspects of HIV/AIDS, including HIV-related opportunistic infections (in English and Spanish)
The MedlinePlus encyclopedia has a page on cryptococcal meningitis (in English and Spanish)
AIDS InfoNet provides fact sheets on many HIV/AIDS topics, including a fact sheet on cryptococcal meningitis (in several languages) and treatment guidelines for opportunistic infections
PMCID: PMC3014618  PMID: 21253011
25.  Primate Models in Women’s Health: Inflammation and Atherogenesis in Female Cynomolgus Macaques (Macaca fascicularis) 
American journal of primatology  2009;71(9):766-775.
Female cynomolgus monkeys are excellent models for understanding cardiovascular disease and the relationships between inflammatory processes and conditions such as atherogenesis. This review summarizes published research findings obtained through comprehensive, multidisciplinary, multi-investigator studies in nonhuman primates over the past two decades. These studies examined the effects of exogenous estrogens and dietary soy protein/isoflavones (IFs) on atherosclerosis, circulating biomarkers, and tissue inflammation in pre- and postmenopausal female cynomolgus monkeys. Inflammation may play a role in the initiation and progression of disease, be a consequence of the disease, or both. Circulating and tissue biomarkers with inflammatory and anti-inflammatory characteristics (including adhesion molecules such as e-selectin, VCAM-1, and ICAM-1, chemokines such as MCP-1, cytokines such as interleukins, and acute phase reactants such as CRP, and others) may be useful indicators of disease status. Treatment of postmenopausal subjects with estrogen resulted in significant reductions in several key inflammatory mediators as well as atherosclerosis, while dietary IF had a more limited effect on inflammation and atherogenesis. Circulating concentrations of key inflammatory proteins, including monocyte-chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6), were associated with atherosclerosis and lesion characteristics in these animals. In premenopausal female monkeys, a diet enriched in soy protein reduced arterial inflammation as well as atherogenesis in comparison to a diet enriched in casein-lactalbumin. Expression levels of arterial inflammation associated genes (MCP-1, ICAM-1) and markers for inflammatory cell types (macrophages and T cells) correlated with plaque size, were differentially influenced by treatments, and represent potential targets for interventions. Arterial expression of estrogen receptor α, the key mediator of estrogenic effects, was inversely correlated with plaque size and indices of inflammation, suggestive of an atheroprotective role. The findings provide additional evidence that circulating inflammatory markers (particularly MCP-1) may be useful indicators of atherosclerotic disease progression and responses to treatment in female primates, and that estrogens and dietary soy may inhibit atherogenesis in part through anti-inflammatory mechanisms.
PMCID: PMC3753776  PMID: 19530126
inflammation; atherogenesis; estrogen receptor; macrophage; T cell

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