To examine change in health-related quality of life (HRQoL) in association with clinical outcomes of neuropsychiatric (NP) events in SLE.
An international study evaluated newly diagnosed SLE patients for NP events attributed to SLE and non-SLE causes. Outcome of events was determined by physician-completed 7-point scale and compared to patient-completed SF-36 questionnaires. Statistical analysis used linear mixed-effects regression models with patient specific random effects.
274 patients (92% female; 68% Caucasian), from a cohort of 1400, had ≥ 1 NP event where the interval between assessments was 12.3 ± 2 months. The overall difference in change between visits in mental component summary (MCS) scores of the SF-36 was significant (p<0.0001) following adjustments for gender, ethnicity, center and previous score. A consistent improvement in NP status (N=295) was associated with an increase in the mean(SD) adjusted MCS score of 3.66(0.89) in SF-36 scores. Between paired visits where NP status consistently deteriorated (N=30), the adjusted MCS score decreased by 4.00(1.96). For the physical component summary (PCS) scores the corresponding changes were +1.73(0.71) and −0.62(1.58) (p<0.05) respectively. Changes in SF-36 subscales were in the same direction (p<0.05; with the exception of role physical). Sensitivity analyses confirmed these findings. Adjustment for age, education, medications, SLE disease activity, organ damage, disease duration, attribution and characteristics of NP events did not substantially alter the results.
Changes in SF-36 summary and subscale scores, in particular those related to mental health, are strongly associated with the clinical outcome of NP events in SLE patients.
Systemic lupus erythematosus; Neuropsychiatric; Inception cohort; Health related quality of life; SF-36
Oxidative stress is proposed as an important factor in osteoarthritis (OA). We therefore investigated the expression of the three superoxide dismutase (SOD) antioxidant enzymes in OA.
SOD expression was determined by real-time polymerase chain reaction and immunohistochemistry using human femoral head cartilage. SOD2 expression in Dunkin Hartley guinea pig knee articular cartilage was determined by immunohistochemistry. The DNA methylation status of the SOD2 promoter was determined using bisulfite sequencing. RNA interference was used to determine the consequence of SOD2 depletion on the levels of reactive oxygen species (ROS) using MitoSOX™ and collagenases, matrix metalloproteinase 1 (MMP-1) and MMP-13, gene expression.
All three SOD were abundantly expressed in human cartilage but were markedly down-regulated in end-stage OA cartilage, especially SOD2. In the Dunkin Hartley guinea pig spontaneous OA model SOD2 expression was decreased in the medial tibial chondyle cartilage prior to, and following, the development of OA-like lesions. The SOD2 promoter had significant DNA methylation alterations in OA cartilage. Depletion of SOD2 in chondrocytes gave an increase in ROS but a decrease in collagenase expression.
This is the first comprehensive expression profile of all SOD genes in cartilage and importantly, using an animal model, we show that a reduction in SOD2 is associated with the earliest stages of OA. We found that a decrease in SOD2 associates with an increase in ROS and but a reduction of collagenase gene expression, demonstrating the complexities of ROS function.
Osteoarthritis; chondrocytes; superoxide dismutase; gene expression
To examine whether erosive hand osteoarthritis (OA) is associated with knee subchondral bone attrition (SBA) and systemic bone mineral density (BMD).
Associations of MRI-defined knee SBA with radiographic erosive hand OA were evaluated in 1253 Framingham participants using logistic regression with generalised estimating equations. We also examined the association between the number of erosive OA finger joints and SBA adjusted for the number of non-erosive OA finger joints. Associations between erosive hand OA and femoral neck BMD were explored in 2236 participants with linear regression. Analyses were adjusted for age, sex and body mass index.
Participants with erosive hand OA had increased odds of knee SBA (OR=1.60, 95% CI 1.07 to 2.38). The relation between the number of erosive OA finger joints and SBA became non-significant when adjusted for the number of non-erosive OA joints as a proxy for the burden of disease. There was a non-significant trend towards higher BMD in erosive hand OA compared with participants without hand OA.
Erosive hand OA was associated with knee SBA, but the relation might be best explained by a heightened burden of disease. No significant relation of erosive hand OA with BMD was found.
There is an enrichment of immune response genes that are subject to copy number variations (CNVs). However, there is limited understanding of their impact on susceptibility to human diseases. CC chemokine ligand 3 like-1 (CCL3L1) is a potent ligand for the HIV coreceptor, CC chemokine receptor 5 (CCR5), and we have demonstrated previously an association between CCL3L1- gene containing segmental duplications and polymorphisms in CCR5 and HIV/AIDS susceptibility. Here, we determined the association between these genetic variations and risk of developing systemic lupus erythaematosus (SLE), differential recruitment of CD3+ and CD68+ leukocytes to the kidney, clinical severity of SLE reflected by autoantibody titres and the risk of renal complications in SLE.
We genotyped 1084 subjects (469 cases of SLE and 615 matched controls with no autoimmune disease) from three geographically distinct cohorts for variations in CCL3L1 and CCR5.
Deviation from the average copy number of CCL3L1 found in European populations increased the risk of SLE and modified the SLE-influencing effects of CCR5 haplotypes. The CCR5 human haplogroup (HH)E and CCR5-Δ32-bearing HHG*2 haplotypes were associated with an increased risk of developing SLE. An individual’s CCL3L1–CCR5 genotype strongly predicted the overall risk of SLE, high autoantibody titres, and lupus nephritis as well as the differential recruitment of leukocytes in subjects with lupus nephritis. The CCR5 HHE/HHG*2 genotype was associated with the maximal risk of developing SLE.
CCR5 haplotypes HHE and HHG*2 strongly influence the risk of SLE. The copy number of CCL3L1 influences risk of SLE and modifies the SLE-influencing effects associated with CCR5 genotypes. These findings implicate a key role of the CCL3L1–CCR5 axis in the pathogenesis of SLE.
Many identified genetic risk factors for SLE contribute to the function of the immune system, which has expanded our understanding of disease pathogenesis. We outline the genetic variants in the recently identified SLE-associated loci, the immunologic pathways affected by these gene products, and the disease manifestations linked to these loci. Pathways potentially influenced by SLE risk variants include: apoptosis, DNA degradation and clearance of cellular debris; antigen-presentation; type I interferon, Toll-like receptor and NFκB activation; defective clearance of immune complexes containing nuclear antigens; B- and T-cell function and signaling; and monocyte and neutrophil function and signaling. These identified SLE susceptibility loci are predominantly common variants that have been confirmed among multiple ancestries, suggesting shared mechanisms in disease etiology. Ongoing genetic studies continue the investigation of specific functional variants, and their potential consequences upon immune dysregulation, enhancing our understanding of links between genotypes and specific disease manifestations. The next generation sequencing explores the identification of causal rare variants that may contribute robust genetic effects to developing SLE. Novel insights coming from genetic studies of SLE provide the opportunity to elucidate pathogenic mechanisms as well as contribute to the development of innovative therapeutic targets for this complex disease.
Systemic lupus erythematosus; Genetic; Genome wide association studies; Interferon pathway; Cell signaling
This study investigated factors that may influence the prevalence and timing of appearance of rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies during the pre-clinical phase of rheumatoid arthritis (RA) development.
243 serial pre-diagnosis serum samples from 83 subjects with RA were examined for the presence of RF and anti-CCP antibodies.
57% and 61% of subjects had at least one pre-diagnosis sample positive for RF or anti-CCP, respectively. Gender and race were not significantly associated with the prevalence or timing of pre-clinical antibody appearance. Pre-clinical anti-CCP positivity was strongly associated with the development of erosive RA (OR 4.64; 95% CI 1.71–12.63; p=0.003), but RF was not (p=0.11). Additionally, as age at the time of diagnosis of RA increased the duration of pre-diagnosis antibody positivity for RF and anti-CCP increased, with the longest duration of pre-clinical antibody positivity seen in patients diagnosed with RA over the age of 40. In no subjects did symptom onset precede the appearance of RF or anti-CCP antibodies.
The period of time that RF and anti-CCP are present prior to diagnosis lengthens as the age at the time of diagnosis of RA increases. This finding suggests that factors such as genetic risk or environmental exposures influencing the temporal relationship between the development of RA-related autoantibodies and clinically-apparent disease onset may differ with age.
autoantibody; rheumatoid arthritis; rheumatoid factor; anti-cyclic citrullinated peptide antibody
Chronic widespread pain (CWP) is a common disorder affecting ~10% of the general population and has an estimated heritability of 48-52%. In the first large-scale genome-wide association study (GWAS) meta-analysis, we aimed to identify common genetic variants associated with CWP.
We conducted a GWAS meta-analysis in 1,308 female CWP cases and 5,791 controls of European descent, and replicated the effects of the genetic variants with suggestive evidence for association in 1,480 CWP cases and 7,989 controls (P<1×10−5). Subsequently, we studied gene expression levels of the nearest genes in two chronic inflammatory pain mouse models, and examined 92 genetic variants previously described associated with pain.
The minor C-allele of rs13361160 on chromosome 5p15.2, located upstream of CCT5 and downstream of FAM173B, was found to be associated with a 30% higher risk of CWP (MAF=43%; OR=1.30, 95%CI=1.19-1.42, P=1.2×10−8). Combined with the replication, we observed a slightly attenuated OR of 1.17 (95%CI=1.10-1.24, P=4.7×10−7) with moderate heterogeneity (I2=28.4%). However, in a sensitivity analysis that only allowed studies with joint-specific pain, the combined association was genome-wide significant (OR=1.23, 95%CI=1.14-1.32, P=3.4×10−8, I2=0%). Expression levels of Cct5 and Fam173b in mice with inflammatory pain were higher in the lumbar spinal cord, not in the lumbar dorsal root ganglions, compared to mice without pain. None of the 92 genetic variants previously described were significantly associated with pain (P>7.7×10−4).
We identified a common genetic variant on chromosome 5p15.2 associated with joint-specific CWP in humans. This work suggests that CCT5 and FAM173B are promising targets in the regulation of pain.
Gene Polymorphism; Fibromyalgia/Pain Syndromes; Epidemiology
Patients with normal (mean pulmonary arterial pressure ≤20 mmHg) and borderline mean pulmonary pressures (mPAP) (boPAP; 21–24 mmHg) are “at risk” of developing pulmonary hypertension(PH). The objectives of this analysis were 1)to examine the baseline characteristics in systemic sclerosis(SSc) with Normal and boPAP, and 2) to explore long term outcomes in SSc patients with boPAP vs. Normal hemodynamics.
PHAROS is a multicenter prospective longitudinal cohort of patients with SSc “at risk” or recently diagnosed with resting PH on right heart catheterization (RHC). Baseline clinical characteristics, pulmonary function tests, high resolution computed tomography(HRCT), 2-D echocardiogram, and RHC results were analyzed in Normal and boPAP groups.
A total of 206 patients underwent RHC (35 Normal, 28 boPAP, 143 had resting PH). There were no differences in the baseline demographics. Patients in the boPAP group were more likely to have restrictive lung disease (67% vs. 30%), fibrosis on HRCT and a higher estimated right ventricular systolic pressure on echocardiogram (46.3 vs. 36.2mmHg; p<0.05) than patients with Normal hemodynamics. RHC revealed higher pulmonary vascular resistance (PVR) and more elevated mPAP on exercise(mPAP ≥30; 88% vs. 56%) in the boPAP group(p<0.05 for both). Patients were followed for a mean of 25.7 months and 24 patients had a repeat RHC during this period. During follow up, 55% of the boPAP group and 32% of the Normal group developed resting PH (p=NS).
Patients with boPAP have a greater prevalence of abnormal lung physiology, pulmonary fibrosis and presence of exercise mPAP ≥30mmHg.
Pulmonary hypertension; Systemic sclerosis; Borderline; Pulmonary hemodynamics
Obesity is associated with an increased risk of psoriasis; however, its potential impact on the risk of psoriatic arthritis (PsA) remains unclear.
To evaluate the association between body mass index (BMI) and the risk of PsA among patients with psoriasis from the general population.
The authors conducted a cohort study using data from The Health Improvement Network, an electronic medical records database representative of the UK general population, collected between 1995 and 2010. The exposure of interest was the first BMI measured after psoriasis diagnosis and endpoints were incident cases of physician-diagnosed PsA. The authors estimated the RR of PsA after adjusting for age, sex, and histories of trauma, smoking and alcohol consumption.
Among 75 395 individuals with psoriasis (43% male, mean follow-up of 5 years, and mean age of 52 years), 976 developed PsA (incidence rate, 26.5 per 10 000 person-years). The PsA incidence rates increased with increasing BMI. Compared with psoriasis patients with BMI <25 kg/m2, the RRs for developing PsA were 1.09 (0.93–1.28) for BMIs from 25.0 to 29.9, 1.22 (1.02–1.47) for BMIs from 30.0 to 34.9 and 1.48 (1.20–1.81) for BMIs ≥35.0. In our secondary analysis among all individuals, regardless of psoriasis (~2 million), the corresponding multivariate RRs tended to be stronger (1.0, 1.17, 1.57, 1.96; p for trend <0.001).
This general population study suggests that obesity is associated with an increased risk of incident PsA and supports the importance of weight reduction among psoriasis patients who often suffer from the metabolic syndrome and obesity.
Interferon beta (IFNβ) therapy is effective in multiple sclerosis and murine models of arthritis. Surprisingly, systemic IFNβ treatment induces only minimal improvement in rheumatoid arthritis (RA). To explain this paradox, the authors evaluated the mechanism of IFNβ benefit in passive K/BxN arthritis and the effect of IFNβ treatment on RA synovium.
Interleukin 10 (IL-10) null, IL-1 receptor antagonist (IL-1Ra) null, IL-1Ra transgenic and wild-type mice were administered K/BxN serum and in some cases treated with IFNβ or normal saline. Clinical response and histological scores were assessed. Gene expression was measured by quantitative PCR. Serum IL-1Ra and IL-6 were measured by ELISA. Paired synovial biopsy specimens from RA patients pre-IFNβ and post-IFNβ treatment (purified natural fibroblast IFNβ (Frone) subcutaneously three times weekly 6 million IU, 12 million IU or 18 million IU) were immunostained for IL-1Ra and IL-10.
Il1rn transgenic mice had an attenuated course of arthritis, whereas Il1rn−/− and Il10−/− mice had more severe serum transfer arthritis than wild-type mice. Daily IFNβ treatment significantly decreased arthritis severity in Il10−/− but not Il1rn−/− mice. IFNβ treatment did not reduce the histological scores in Il1rn−/− mice or gene expression of articular cytokines and chemokines. Paired synovial biopsy specimens from RA patients treated with IFNβ demonstrated a trend towards increased IL-1Ra and reduced IL-10 expression on day 85 levels compared with pretreatment specimens.
The anti-inflammatory effects of IFNβ in passive K/BxN arthritis are dependent on IL-1Ra, but not IL-10. Systemic IFNβ treatment in RA increases synovial IL-1Ra production, but also decreases IL-10 production.
To compare patterns of arteriographic lesions of the aorta and primary branches in patients with Takayasu’s arteritis (TAK) and giant cell arteritis (GCA).
Patients were selected from two North American cohorts of TAK and GCA. The frequency of arteriographic lesions was calculated for 15 large arteries. Cluster analysis was used to derive patterns of arterial disease in TAK versus GCA and in patients categorised by age at disease onset. Using latent class analysis, computer derived classification models based upon patterns of arterial disease were compared with traditional classification.
Arteriographic lesions were identified in 145 patients with TAK and 62 patients with GCA. Cluster analysis demonstrated that arterial involvement was contiguous in the aorta and usually symmetric in paired branch vessels for TAK and GCA. There was significantly more left carotid (p=0.03) and mesenteric (p=0.02) artery disease in TAK and more left and right axillary (p<0.01) artery disease in GCA. Subclavian disease clustered asymmetrically in TAK and in patients ≤55 years at disease onset and clustered symmetrically in GCA and patients >55 years at disease onset. Computer derived classification models distinguished TAK from GCA in two subgroups, defining 26% and 18% of the study sample; however, 56% of patients were classified into a subgroup that did not strongly differentiate between TAK and GCA.
Strong similarities and subtle differences in the distribution of arterial disease were observed between TAK and GCA. These findings suggest that TAK and GCA may exist on a spectrum within the same disease.
To derive and validate decision trees to categorize rheumatoid arthritis (RA) patients 12 weeks after starting etanercept with or without methotrexate into three groups: patients predicted to achieve low disease activity (LDA) at 1 year; patients predicted to not achieve LDA at 1 year; and patients who needed additional time on therapy to be categorized.
Data from RA patients enrolled in TEMPO were analyzed. Classification and Regression Trees were used to develop and validate decision-tree models with week 12 and earlier assessments that predicted long-term LDA. LDA, defined as DAS28 ≤ 3.2 or Clinical Disease Activity Index (CDAI) ≤ 10.0, was measured at 52 or 48 weeks. Demographics, laboratory data, and clinical data at baseline and through week 12 were analyzed as predictors of response.
Thirty-nine percent (67/172) of patients receiving etanercept and 60% (115/193) of patients receiving etanercept plus methotrexate achieved LDA at week 52. For patients receiving etanercept, 53% were predicted to have LDA, 39% were predicted to not have LDA, and 8% could not be categorized using DAS28 criteria at week 12. For patients receiving etanercept plus methotrexate, 63% were predicted to have LDA, 25% were predicted to not have LDA, and 12% could not be categorized.
Most (80%–90%) patients in TEMPO initiating etanercept with or without methotrexate could be predicted within 12 weeks of starting therapy as likely to have LDA or not at week 52. However, approximately 10%–20% of patients needed additional time on therapy to decide whether to continue treatment.
etanercept; methotrexate; arthritis; rheumatoid; decision tree; prediction
The first genome-wide association study (GWAS) of systemic sclerosis (SSc) demonstrated three non-major histocompatibility complex (MHC) susceptibility loci. The goal of this study was to investigate the impact of these gene variants on survival and severity of interstitial lung disease (ILD) in SSc.
The authors examined 1443 Caucasian SSc patients enrolled in the Genetics versus Environment In Scleroderma Outcome Study (GENISOS) and Scleroderma Family Registry (n = 914 – discovery cohort) and The Johns Hopkins Scleroderma Cohort (n = 529 – replication cohort). Forced vital capacity (FVC)% predicted was used as a surrogate for ILD severity. Five single nucleotide polymorphisms, IRF5 (rs10488631, rs12537284, rs4728142), STAT4 (rs3821236), CD247 (rs2056626) reached genome-wide significance in the SSc-GWAS and were examined in the current study.
Overall, 15.5% of the patients had died over the follow-up period of 5.5 years. The IRF5 rs4728142 minor allele was predictive of longer survival in the discovery cohort (p = 0.021) and in the independent replication cohort (p = 0.047) and combined group (HR: 0.75, 95% CI 0.62 to 0.90, p = 0.002). The association of this SNP with survival was independent of age at disease onset, disease type and autoantibody profile (anticentromere and antitopoisomerase antibodies). The minor allele frequency of IRF5 rs4728142 was 49.4%.
Moreover, IRF5 rs4728142 minor allele correlated with higher FVC% predicted at enrolment (p = 0.019). Finally, the IRF5 rs4728142 minor allele was associated with lower IRF5 transcript expression in patients and controls (p = 0.016 and p = 0.034, respectively), suggesting that the IRF5, rs4728142 SNP, may be functionally relevant.
An SNP in the IRF5 promoter region (rs4728142), associated with lower IRF5 transcript levels, was predictive of longer survival and milder ILD in patients with SSc.
Inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), shares clinical and immunological features with psoriasis. Genome-wide association studies have found common susceptibility genes. However, epidemiologic data evaluating the association between psoriasis, psoriatic arthritis and risk of IBD are sparse. We aimed to evaluate the association between psoriasis, psoriatic arthritis and incident CD and UC among women in the USA.
174 476 women were enrolled in the Nurses’ Health Study (NHS) (1996–2008) and NHS II (1991–2007). Lifetime history of physician-diagnosed psoriasis and psoriatic arthritis was confirmed by supplementary questionnaires. Information on CD and UC was obtained by self-reported questionnaires and confirmed by medical record review.
We documented 188 incident cases of CD and 240 incident cases of UC during follow-up. Psoriasis was associated with a significantly increased risk of subsequent CD with a multivariate-adjusted relative risk (RR) of 4.00 (95% CI 1.72 to 9.27) for NHS and 3.76 (1.82 to 7.74) for NHS II. By contrast, we did not observe a significant increase in risk of UC associated with psoriasis. In a pooled analysis of both cohorts, women with psoriasis experienced a significantly increased risk of CD (RR, 3.86, 95% CI 2.23 to 6.67), but not UC (RR, 1.17, 95% CI 0.41 to 3.36). The risk of CD was especially pronounced among psoriatics with concomitant psoriatic arthritis (RR, 6.43, 95% CI 2.04 to 20.32).
Psoriasis with concomitant psoriatic arthritis is associated with an increased risk of incident CD.
We evaluated the information content of knee bone scintigraphy, including pattern, localization and intensity of retention relative to radiographic features of knee osteoarthritis (rOA), knee alignment, and knee symptoms.
A total of 308 knees (159 subjects) with symptomatic and radiographic knee OA (rOA) of at least one knee were assessed by late phase technetium-99m-methylene disphosphonate bone scintigraph, fixed-flexion knee radiograph, full limb radiograph for knee alignment, and for self-reported knee symptom severity. Generalized linear models were used to control for within subject correlation of knee data.
The compartmental localization (medial versus lateral) and intensity of knee bone scan retention were associated with the pattern (varus versus valgus) (p<0.001) and severity (p=0.0008) of knee malalignment, and localization and severity of rOA (p<0.0001). Bone scan agent retention in the tibiofemoral, but not patellofemoral compartment, was associated with severity of knee symptoms (p=0.0009), and persisted after adjusting for rOA (p=0.0012).
To our knowledge, this is the first study describing a relationship between knee malalignment, joint symptom severity, and compartment specific abnormalities by bone scintigraphy. This work demonstrates that bone scintigraphy as a sensitive and quantitative indicator of symptomatic knee OA. Used selectively, bone scintigraphy is a dynamic imaging modality that holds great promise as a clinical trial screening tool and outcome measure.
osteoarthritis; bone scintigraphy; malalignment; knee
There is increasing evidence that variation in gene copy number (CN) influences clinical phenotype. The low-affinity Fcγ receptor 3B (FCGR3B) located in the FCGR gene cluster is a CN polymorphic gene involved in the recruitment to sites of inflammation and activation of polymorphonuclear neutrophils (PMNs). Given recent evidence that low FCGR3B CN is a risk factor for systemic but not organ-specific autoimmune disease and the potential importance of PMN in the pathophysiology of rheumatoid arthritis (RA), the authors hypothesised that FCGR3B gene dosage influences susceptibility to RA.
FCGR3B CN was measured in 643 cases of RA and 461 controls from New Zealand (NZ), with follow-up analysis in 768 cases and 702 controls from the Netherlands and 250 cases and 211 controls from the UK. All subjects were of Caucasian ancestry.
Significant evidence for an association between CN <2 and RA was observed in the Dutch cohort (OR 2.01 (95% CI 1.37 to 2.94), p=3×10–4) but not in the two smaller cohorts (OR 1.45 (95% CI 0.92 to 2.26), p=0.11 and OR 1.33 (95% CI 0.58 to 3.02), p=0.50 for the NZ and UK populations, respectively). The association was evident in a meta-analysis which included a previously published Caucasian sample set (OR 1.67 (95% CI 1.28 to 2.17), p=1.2×10–4).
One possible mechanism to explain the association between reduced FCGR3B CN and RA is the reduced clearance of immune complex during infl ammation. However, it is not known whether the association between RA and FCGR3B CN is aetiological or acts as a proxy marker for another biologically relevant variant. More detailed examination of genetic variation within the FCGR gene cluster is required.
To assess if genetic variation in the PACE4 gene, PCSK6, influences the risk for symptomatic knee OA.
Ten PCSK6 single nucleotide polymorphisms (SNP) were tested for association in a discovery cohort of radiographic knee OA (n= 156 asymptomatic and 600 symptomatic cases). Meta-analysis of the minor allele at rs900414 was performed in three additional independent cohorts (total n=674 asymptomatic and 2068 symptomatic). Pcsk6 knockout (KO) mice and wildtype C57BL/6 mice were compared in a battery of algesiometric assays, including hypersensitivity in response to intraplantar substance P; pain behaviours in response to intrathecal substance P; and pain behaviour in the abdominal constriction test.
In the discovery cohort of radiographic knee OA, an intronic SNP at rs900414 was significantly associated with symptomatic OA. Replication in three additional cohorts confirmed that the minor allele at rs900414 was consistently increased among asymptomatic compared to symptomatic radiographic knee OA cases in all four cohorts. A fixed-effects meta-analysis yielded an odds ratio =1.35 (95% CI 1.17, 1.56; p-value 4.3×10−5 and no significant between-study heterogeneity). Studies in mice revealed that Pcsk6 knockout (KO) mice were significantly protected against pain in a battery of algesiometric assays.
These results suggest that a variant in PCSK6 is strongly associated with protection against pain in knee OA, offering some insight as to why in the presence of the same structural damage, some individuals develop chronic pain and others are protected. Studies in Pcsk6 null mutant mice further implicate PACE4 in pain.
Knee osteoarthritis; pain; PACE4; genetic association; SNP
It is hypothesised that, like low bone density and fracture, thin cartilage predisposes to osteoarthritis (OA). Inferences about the effects of cartilage thickness on the development of OA can be made by evaluating the status of an unaffected non-diseased contralateral knee, in persons with unilateral OA, which we shall label the “premorbid knee”. The primary objective of this analysis was to compare cartilage thickness in premorbid knees with non-OA knees drawn from persons without any knee OA to determine if cartilage in the premorbid knee was thinner than in the knee drawn from someone without OA in either knee.
From 2002 to 2005, The Framingham Osteoarthritis Study recruited subjects without respect to OA from the community. We obtained posteroanterior, semiflexed and lateral films of both knees and knee magnetic resonance imaging to quantify cartilage volume in one knee. The cartilage plates of the patella, medial and lateral femur, medial and lateral tibia were quantified, using a 3D FLASH-water excitation sequence (in plane resolution 0.3×0.3 mm, 512 matrix, slice thickness 1.5 mm) and digital post-processing, involving three-dimensional reconstruction. Radiographs were used to define the OA status of knees with disease defined as Kellgren and Lawrence grade ≥2 and or patellofemoral OA on the lateral film. Of 1020 participants included in this analysis, 720 had no OA in either knee (no-knee OA sample), and 55 subjects had no OA in the knee that was examined using magnetic resonance imaging and OA in the contralateral knee (premorbid knee OA sample). We compared cartilage thickness and percentage of cartilage coverage (total bone interface covered with cartilage) between these groups. After initial plate-specific univariate comparisons we performed a multiple regression to assess the association between OA status (premorbid versus no OA knee) and cartilage thickness adjusting for age, sex and body mass index. We used the Generalised Estimating Equation to account for correlation between plates. To further determine if the cartilage was diffusely thinned or had only increased areas of denuded cartilage, we removed plates with denuded areas (less than 95% cartilage coverage) from the analysis.
55% of subjects were women. There was no difference in cartilage thickness between the premorbid knees and the no-knee OA sample. After adjusting for age, sex and body mass index and removing plates with less than 95% coverage from the analysis, we found the same or even thicker cartilage in premorbid knees compared with the knee OA sample.
Premorbid knees do not have diffuse cartilage thinness. Rather the cartilage is normal or thicker with denuded areas suggesting that this may be the initial pathology rather than diffuse thinning.
An association between rheumatoid factor (RF) and increased mortality has been described in individuals with rheumatoid arthritis. The objective of this study was to determine the effect of RF on mortality and coronary heart disease (CHD) in the general population.
Subjects were participants in a population-based study focused on cardiovascular disease who attended for a study visit during the years 1974–84. RF was measured and information obtained on cardiovascular risk factors, joint symptoms and erythrocyte sedimentation rate (ESR). The subjects were followed with respect to mortality and incident CHD through 2005. Adjusted comparison of overall survival and CHD event-free survival in RF-positive versus RF-negative subjects was performed using Cox proportional hazards regression models.
Of 11 872 subjects, 140 had positive RF. At baseline RF was associated with diabetes mellitus and smoking and inversely associated with serum cholesterol. RF-positive subjects had increased all-cause mortality (HR 1.47, 95% CI 1.19 to 1.80) and cardiovascular mortality (HR 1.57, 95% CI 1.15 to 2.14) after adjusting for age and sex. Further adjustment for cardiovascular risk factors and ESR only modestly attenuated this effect. An increase in CHD among the RF-positive subjects did not reach statistical significance (HR 1.32, 95% CI 0.96 to 1.81, adjusted for age and sex). Subjects with RF but without joint symptoms also had increased overall mortality and cardiovascular mortality (HR for overall mortality 1.33, 95% CI 1.01 to 1.74, after adjustment).
In a general population cohort, RF was associated with increased all-cause mortality and cardiovascular mortality after adjustment for cardiovascular risk factors, even in subjects without joint symptoms.
Given the inconsistency of remission definitions in rheumatoid arthritis (RA) trials, the goal of this American College of Rheumatology/European League Against Rheumatism committee was to define remission.
The committee instructed a working group that a new remission definition, among other requirements, needed to allow for little, if any, active clinical disease and to be defined using the core set of outcome measures for RA trials and that those in remission at one time needed to have a low risk of later worsening function or radiograph progression. Remission was to be defined using trial data for use in trials but needed to anticipate use in a practice setting.
The working group started by evaluating the thresholds for core set measures compatible with remission and determined that patient-reported outcomes contributed importantly to the ability of outcome assessment to distinguish more from less effective treatments. The group created a candidate group of remission definitions to test, including Boolean versions and widely used indexes. Testing how well these candidate definitions predicted later good outcomes, the group found that Disease Activity Score 28 thresholds for remission performed worse than Simplified Disease Activity Index/Clinical Disease Activity Index or Boolean versions. Also, persons with low Disease Activity Score 28 occasionally had high joint counts, which were incompatible with remission. The parent committee chose two definitions: one Boolean (patient had to have all of the following: tender joint count, swollen joint count ≤1, C reactive protein ≤1 mg/dl) and patient global assessment ≤1 (on a 0–10 scale) and one Simplified Disease Activity Index ≤3.3.
The American College of Rheumatology/European League Against Rheumatism has promulgated two new similar definitions of remission for RA trials.