Chemokines are low-molecular-weight chemotactic cytokines that have been shown to play a central role in the perivascular transmigration and accumulation of specific subsets of leukocytes at sites of tissue damage. Using in situ hybridization (ISH), we investigated the mRNA induction of macrophage inflammatory protein 2 (MIP-2), MIP-1α, monocyte chemoattractant protein 1 (MCP-1), and RANTES. Challenge of infant rats’ brains with Haemophilus influenzae type b intraperitoneally resulted in the time-dependent expression of MIP-2, MIP-1α, MCP-1, and RANTES, which was maximal 24 to 48 h postinoculation. Immunohistochemistry showed significant increases in neutrophils and macrophages infiltrating the meninges, the ventricular system, and the periventricular area. The kinetics of MIP-2, MIP-1α, MCP-1, and RANTES mRNA expression paralleled those of the recruitment of inflammatory cells and disease severity. Administration of anti-MIP-2 or anti-MIP-1α antibodies (Abs) resulted in significant reduction of neutrophils. Administration of anti-MCP-1 Abs significantly decreased macrophage infiltration. Combined studies of ISH and immunohistochemistry showed that MIP-2- and MIP-1α-positive cells were neutrophils and macrophages. MCP-1-positive cells were neutrophils, macrophages, and astrocytes. Expression of RANTES was localized predominantly to resident astrocytes and microglia. The present study indicates that blocking of MIP-2 or MIP-1α bioactivity in vivo results in decreased neutrophil influx. These data are also the first demonstration that the C-C chemokine MIP-1α is involved in neutrophil recruitment in vivo.
Amniotic fluid infection with chorioamnionitis is associated with increased risks of morbidity and mortality in children born prematurely. These risks depend on the presence of a fetal inflammatory response. We measured the concentrations of 25 proteins in the blood of 871 infants born before the 28th week of gestation, and examined their placentas for acute inflammation. Newborns who had inflammatory lesions of the placenta were much more likely than their peers (p<0.01) to have elevated blood concentrations of cytokines (IL-1β, IL-6, TNF-alpha), chemokines (IL-8, MIP-1β, RANTES, I-TAC), adhesion molecules (ICAM-1, ICAM-3, E-selectin), matrix metalloproteinases (MMP1, MMP -9), the angiogenic inflammatory factor VEGF and its receptor VEGF-R2 as well as acute phase proteins (SAA and CRP) during first three days after birth. In contrast, newborns with poor placental perfusion had lower levels of inflammatory proteins (p<0.01, IL-6, RANTES, ICAM-1, ICAM-3, VCAM-1, E-selectin, MMP-1, MMP-9, MPO, VEGF). An inverse pattern was found between newborn levels of VEGF and its competitive inhibitor VEGF-R1 in both the inflamed and poorly perfused placenta categories. These results confirm the predictive value of placental histology for the presence or absence of elevated inflammatory response in the newborn.
Inflammation is a hallmark of acute lung injury and chronic airway diseases. In chronic airway diseases, it is associated with profound tissue remodeling. Peroxisome proliferator-activated receptor-α (PPARα) is a ligand-activated transcription factor, that belongs to the nuclear receptor family. Agonists for PPARα have been recently shown to reduce lipopolysaccharide (LPS)- and cytokine-induced secretion of matrix metalloproteinase-9 (MMP-9) in human monocytes and rat mesangial cells, suggesting that PPARα may play a beneficial role in inflammation and tissue remodeling.
We have investigated the role of PPARα in a mouse model of LPS-induced airway inflammation characterized by neutrophil and macrophage infiltration, by production of the chemoattractants, tumor necrosis factor-α (TNF-α), keratinocyte derived-chemokine (KC), macrophage inflammatory protein-2 (MIP-2) and monocyte chemoattractant protein-1 (MCP-1), and by increased MMP-2 and MMP-9 activity in bronchoalveolar lavage fluid (BALF). The role of PPARα in this model was studied using both PPARα-deficient mice and mice treated with the PPARα activator, fenofibrate.
Upon intranasal exposure to LPS, PPARα-/- mice exhibited greater neutrophil and macrophage number in BALF, as well as increased levels of TNF-α, KC, MIP-2 and MCP-1, when compared to PPARα+/+ mice. PPARα-/- mice also displayed enhanced MMP-9 activity. Conversely, fenofibrate (0.15 to 15 mg/day) dose-dependently reduced the increase in neutrophil and macrophage number induced by LPS in wild-type mice. In animals treated with 15 mg/day fenofibrate, this effect was associated with a reduction in TNF-α, KC, MIP-2 and MCP-1 levels, as well as in MMP-2 and MMP-9 activity. PPARα-/- mice treated with 15 mg/day fenofibrate failed to exhibit decreased airway inflammatory cell infiltrate, demonstrating that PPARα mediates the anti-inflammatory effect of fenofibrate.
Using both genetic and pharmacological approaches, our data clearly show that PPARα downregulates cell infiltration, chemoattractant production and enhanced MMP activity triggered by LPS in mouse lung. This suggests that PPARα activation may have a beneficial effect in acute or chronic inflammatory airway disorders involving neutrophils and macrophages.
PPARα; lipopolysaccharide; inflammation; neutrophil; macrophage; matrix metalloproteinase; mouse
Background and purpose
Little is known about biochemical mediators that correlate with the initiation and progression of knee osteoarthritis (OA). We therefore valuated the roles of cytokines and metalloenzymes in knee OA in relation to OA grading, age, and BMI.
Patients and methods
A multiplex ELISA-based immunoassay (Luminex technology) was used to measure biochemical mediators in the synovial fluid (SF) of 82 patients undergoing knee surgery. All patients were classified according to age, BMI, and OA grade. 24 patients had no signs of OA (knee reconstruction surgeries). The mediators that were tested for included interleukins (IL-1Ra, IL-6, IL-7, and IL-18), chemokines (CCL2 (MCP-1), CCL3 (MIP-1a), and CXCL8 (IL-8)), growth factors (HGF and VEGF), and matrix metalloproteinases (MMP-1, MMP-2, MMP-9, and MMP-13).
There was a correlation between IL-7 levels in SF and age (p < 0.01). The 11 highest IL-7 levels were seen in patients who were aged between 59 and 72 but had different OA grades. In contrast, all patients who had severe OA in all 3 knee compartments (pan-OA) had only low or medium IL-7 levels. There was a negative correlation between MMP-1 levels in synovial fluid and grade of OA (p < 0.001). Correlation studies between pairs of mediators revealed two groups of mediators that are important in OA progression, dominated by MCP-1 and IL-1Ra.
IL-7 levels in SF are elevated in elderly people suffering from OA of different grades, but they are depressed in patients with severe 3-compartment OA, possibly due to widely impaired chondrocytes embedded in the affected cartilage tissue. The observed decrease in MMP-1 levels in SF, which is dependent on the severity of OA, may be caused by deterioration of superficial cartilage layers during progression of OA.
We characterized the expression of the β-chemokines macrophage inflammatory protein 1α (MIP-1α), MIP-1β, and RANTES by primary human microglia after exposure to Cryptococcus neoformans. In the absence of specific antibody, C. neoformans failed to elicit a chemokine response, while in the presence of specific antibody, microglia produced MIP-1α and MIP-1β in amounts comparable to those induced by lipopolysaccharide. RANTES was also induced but at much lower levels. In addition to MIP-1α and MIP-1β mRNA, we observed a robust induction of monocyte chemoattractant protein 1 and interleukin-8 mRNA following incubation of microglia with opsonized C. neoformans. In contrast, cryptococcal polysaccharide did not induce a chemokine response even when specific antibody was present and inhibited the MIP-1α induction associated with antibody-mediated phagocytosis of C. neoformans. The role of the Fc receptor in the observed chemokine induction was explored in several experiments. Treatment of microglia with cytochalasin D inhibited internalization of C. neoformans but did not affect MIP-1α induction. In contrast, treatment with herbimycin A, a tyrosine kinase inhibitor, inhibited MIP-1α induction. Microglia stimulated with immobilized murine immunoglobulin also produced MIP-1α and RANTES (MIP-1α > RANTES). Our results show that microglia produce several chemokines when stimulated by C. neoformans in the presence of specific antibody and that this process is likely to be mediated by Fc receptor activation. This response can be down-regulated by cryptococcal capsular polysaccharide. These findings suggest a mechanism by which C. neoformans infections fail to induce strong inflammatory responses in patients with cryptococcal meningoencephalitis and have important implications for antibody therapy.
CC chemokines constitute a novel class of cytokines that attract and activate monocytes and lymphocytes, as well as basophil and eosinophil leukocytes, with distinct target cell profiles, and are believed to be involved in the regulation of different types of inflammation. The action of the recently identified monocyte chemotactic protein 3 (MCP- 3) on human basophil and eosinophil function was studied and compared with that of other CC chemokines. In basophils, MCP-3, MCP-1, RANTES, and macrophage inflammatory protein (MIP)-1 alpha all induced cytosolic- free calcium concentration ([Ca2+]i) changes and, with different efficacies, chemotaxis (RANTES = MCP-3 >> MCP-1 > MIP-1 alpha), histamine release (MCP-1 = MCP-3 >> RANTES > MIP-1 alpha), and leukotriene C4 formation, after IL-3 pretreatment (MCP-1 = MCP-3 >> RANTES > MIP-1 alpha). Thus, MCP-3 was as effective as MCP-1 as an inducer of mediator release, and as effective as RANTES as a stimulus of basophil migration. In contrast to MCP-1, MCP-3 was also a stimulus for eosinophils, and induced [Ca2+]i changes and chemotaxis as effectively as RANTES, which is the most potent chemotactic cytokine for these cells. Desensitization of the transient changes in [Ca2+]i was used to assess receptor usage. In basophils, stimulation with MCP-3 prevented responsiveness to MCP-1 and RANTES, but not to MIP-1 alpha. No single CC chemokine (except for MCP-3 itself) affected the response to MCP-3, however, which was prevented only when the cells were prestimulated with both MCP-1 and RANTES. In eosinophils, by contrast, cross-desensitization between RANTES and MCP-3 was obtained. RANTES and to a lesser extent MCP-3 also desensitized eosinophils toward MIP-1 alpha. The desensitization data suggest the existence of three chemokine receptors: (a) a MCP-1 receptor expressed on basophils but not eosinophils that is activated by MCP-1 and MCP-3; (b) a RANTES receptor in basophils and eosinophils that is activated by RANTES and MCP-3; and (c) a MIP-1 alpha receptor that is activated by MIP-1 alpha, RANTES and, more weakly, by MCP-3. This study shows that MCP-3 combines the properties of RANTES, a powerful chemoattractant, and MCP-1, a highly effective stimulus of mediator release, and thus has a particularly broad range of activities toward both human basophil and eosinophil leukocytes.
Adjuvant-induced arthritis (AIA) is one of many animal models of rheumatoid arthritis, a disease characterized by a T-lymphocyte and macrophage cellular infiltrate. We have characterized the development of this disease model with respect to chemokine expression. Increased levels of two chemokines, RANTES, a T-lymphocyte and monocyte chemo-attractant, and KC a chemoattractant for neutrophils, were found in whole blood and in the joint. Surprisingly, levels of MIP-1alpha, another T-lymphocyte and monocyte chemoattractant, were unchanged throughout the course of the disease in whole blood and only slightly elevated in the joint. RANTES expression plays an important role in the disease since a polyclonal antibody to RANTES greatly ameliorated symptoms in animals induced for AIA and was found to be as efficacious as treatment with indomethacin, a non-steroidal anti inflammatory. Polyclonal antibodies to either MIP-1alpha or KC were ineffective. This is the first report to show the importance of RANTES in the development of AIA.
The relationship between serum biomarkers and clinical expressions of COPD is limited. We planned to further describe this association using markers of inflammation and injury and repair.
We studied lung function, comorbidities, exercise tolerance, BODE index, and quality of life in 253 COPD patients and recorded mortality over three years. Serum levels of Interleukins 6,8 and16, tumor necrosis factor alpha (TNF α) [inflammatory panel], vascular endothelial growth factor (VEGF), and matrix metalloproteinase 9 (MMP-9) [injury and repair panel] and pulmonary and activation-regulated chemokine (PARC/CCL-18) and monocyte chemotactic protein 1 (MCP-1/CCL2) [chemoattractant panel] were measured. We related the pattern of the biomarker levels to minimal clinically important differences (MCID) using a novel visualization method [ObServed Clinical Association Results (OSCAR) plot].
Levels of the inflammatory markers IL-6, TNF α were higher and those of injury and repair lower (p < 0.01) with more advanced disease (GOLD 1 vs. 4). Using the OSCAR plot, we found that patients in the highest quartile of inflammatory and lowest quartile of injury and repair biomarkers level were more clinically compromised and had higher mortality (p < 0.05).
In COPD, serum biomarkers of inflammation and repair are distinctly associated with important clinical parameters and survival.
Exercise; Inflammation; Phenotypes; Repair; Survival
It is characteristic for virus infections that monocytes/macrophages and lymphocytes infiltrate infected tissue while neutrophils are absent. To understand the mechanisms selectively attracting mononuclear cells in viral diseases, we examined in an influenza A virus model the expression and regulation of chemokines as candidate molecules responsible for the immigration of leukocytes into inflamed tissue. After influenza A virus infection of human monocytes, a rapid expression of the mononuclear cell attracting CC-chemokine genes MIP-1, MCP-1, and RANTES occurred which was followed by the release of chemokine proteins. In striking contrast to CC-chemokines, the expression of the prototype neutrophil CXC-chemoattractants IL-8 and GRO-alpha was completely suppressed after influenza A infection. The release of other neutrophil chemotactic factors was excluded by microchemotaxis assays. These results suggest that the virus-specific induction of mononuclear cell-attracting chemokines accounts for the preferential influx of mononuclear leukocytes into virus-infected tissue.
Herniated disc (HD) is a common health problem that is resolved by surgery unless spontaneous resorption occurs. HD tissue contains abundant macrophage infiltration and high levels of matrix metalloproteinases (MMPs) MMP-3 and MMP-7. We developed a model system in which disc tissue or isolated chondrocytes from wild-type or MMP-null mice were cocultured with peritoneal macrophages and used this system to investigate the role of MMPs and chondrocyte/macrophage interactions in disc resorption. We observed a marked enhancement of MMP-3 protein and mRNA in chondrocytes after exposure to macrophages. Chondrocytic MMP-3, but not MMP-7, was required for disc resorption, as determined by assaying for a reduction in wet weight and proteoglycan content after 3 days of coculture. Surprisingly, chondrocyte MMP-3 was required for the generation of a macrophage chemoattractant and the subsequent infiltration of the disc tissue by proteolytically active macrophages. We conclude that macrophage induction of chondrocyte MMP-3 plays a major role in disc resorption by mechanisms that include the generation of a bioactive macrophage chemoattractant.
Atherosclerosis is characterized by a chronic inflammatory disease, and chemokines play an important role in both initiation and progression of atherosclerosis development. Leukotactin-1 (Lkn-1/CCL15), a new member of the human CC chemokine family, is a potent chemoattractant for leukocytes. Our previous study has demonstrated that Lkn-1/CCL15 plays a role in the initiation of atherosclerosis, however, little is currently known whether Lkn-1/CCL15 is associated with the progression of atherosclerosis. Matrix metalloproteinases (MMPs) in human coronary atherosclerotic lesions play a crucial role in the progression of atherosclerosis by altering the vulnerability of plaque rupture. In the present study, we examined whether Lkn-1/CCL15 modulates MMP-9 release, which is a prevalent form expressed by activated macrophages and foam cells. Human THP-1 monocytic cells and/or human peripheral blood monocytes (PBMC) were treated with phorbol myristate acetate to induce their differentiation into macrophages. Foam cells were prepared by the treatment of THP-1 macrophages with human oxidized LDL. The macrophages and foam cells were treated with Lkn-1/CCL15, and the levels of MMP-9 release were measured by Gelatin Zymography. Lkn-1/CCL15 significantly enhanced the levels of MMP-9 protein secretion from THP-1 monocytic cells-derived macrophages, human PBMC-derived macrophages, as well as macrophage-derived foam cell in a dose dependent manner. Our data suggest that the action of Lkn-1/CCL15 on macrophages and foam cells to release MMP-9 may contribute to plaque destabilization in the progression of atherosclerosis.
Chemokine; Lkn-1/CCL15; MMP-9; foam cell; atherosclerosis
The chemokines monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1α (MIP-1α) aid in directing leukocytes to specific locales within the brain and spinal cord during central nervous system inflammation. However, it remains unclear how these chemokines exert their actions across a vascular barrier, raising speculation that interaction with endothelial cells might be required. Therefore, experiments were performed to determine whether binding domains for these chemokines exist along the outer surface of brain microvessels, a feature that could potentially relay chemokine signals from brain to blood. Using a biotinylated chemokine binding assay with confocal microscopy and three-dimensional image reconstruction, spatially resolved binding sites for MCP-1 and MIP-α around human brain microvessels were revealed for the first time. Binding of labeled MCP-1 and MIP-1α could be inhibited by unlabeled homologous but not heterologous chemokine, and was independent of the presence of heparan sulfate, laminin, or collagen in the subendothelial matrix. This is the first evidence of specific and separate binding domains for MCP-1 and MIP-1α on the parenchymal surface of microvessels, and highlights the prospect that specific interactions of chemokines with microvascular elements influence the extent and course of central nervous system inflammation.
chemokine; monocyte chemoattractant protein; macrophage inflammatory protein-1α; binding; microvessels
Chemokines are involved in recruitment and activation of hematopoietic cells at sites of infection and inflammation. The M3 gene of γHV68, a gamma-2 herpesvirus that infects and establishes a lifelong latent infection and chronic vasculitis in mice, encodes an abundant secreted protein during productive infection. The M3 gene is located in a region of the genome that is transcribed during latency. We report here that the M3 protein is a high-affinity broad-spectrum chemokine scavenger. The M3 protein bound the CC chemokines human regulated upon activation of normal T-cell expressed and secreted (RANTES), murine macrophage inflammatory protein 1α (MIP-1α), and murine monocyte chemoattractant protein 1 (MCP-1), as well as the human CXC chemokine interleukin-8, the murine C chemokine lymphotactin, and the murine CX3C chemokine fractalkine with high affinity (Kd = 1.6 to 18.7 nM). M3 protein chemokine binding was selective, since the protein did not bind seven other CXC chemokines (Kd > 1 μM). Furthermore, the M3 protein abolished calcium signaling in response to murine MIP-1α and murine MCP-1 and not to murine KC or human stromal cell-derived factor 1 (SDF-1), consistent with the binding data. The M3 protein was also capable of blocking the function of human CC and CXC chemokines, indicating the potential for therapeutic applications. Since the M3 protein lacks homology to known chemokines, chemokine receptors, or chemokine binding proteins, these studies suggest a novel herpesvirus mechanism of immune evasion.
Human cytomegalovirus (HCMV), a betaherpesvirus, has developed several ways to evade the immune system, notably downregulation of cell surface expression of major histocompatibility complex class I heavy chains. Here we report that HCMV has devised another means to compromise immune surveillance mechanisms. Extracellular accumulation of both constitutively produced monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor–superinduced RANTES (regulated on activation, normal T cell expressed and secreted) was downregulated in HCMV-infected fibroblasts in the absence of transcriptional repression or the expression of polyadenylated RNA for the cellular chemokine receptors CCR-1, CCR-3, and CCR-5. Competitive binding experiments demonstrated that HCMV-infected cells bind RANTES, MCP-1, macrophage inflammatory protein (MIP)-1β, and MCP-3, but not MCP-2, to the same receptor as does MIP-1α, which is not expressed in uninfected cells. HCMV encodes three proteins with homology to CC chemokine receptors: US27, US28, and UL33. Cells infected with HCMV mutants deleted of US28, or both US27 and US28 genes, failed to downregulate extracellular accumulation of either RANTES or MCP-1. In contrast, cells infected with a mutant deleted of US27 continues to bind and downregulate those chemokines. Depletion of chemokines from the culture medium was at least partially due to continuous internalization of extracellular chemokine, since exogenously added, biotinylated RANTES accumulated in HCMV-infected cells. Thus, HCMV can modify the chemokine environment of infected cells through intense sequestering of CC chemokines, mediated principally by expression of the US28-encoded chemokine receptor.
RANTES; human cytomegalovirus; chemokine receptors; sequestration; monocyte chemoattractant protein 1
Chemokines are inflammatory molecules that act primarily as chemoattractants and as activators of leukocytes. Their role in antigen-specific immune responses is of importance, but their role in disease protection is unknown. Recently it has been suggested that chemokines modulate immunity along more classical Th1 and Th2 phenotypes. However, no data currently exist in an infectious challenge model system. We analyzed the modulatory effects of selected chemokines (interleukin-8 [IL-8], gamma interferon-inducible protein 10 [IP-10], RANTES, monocyte chemotactic protein 1 [MCP-1], and macrophage inflammatory protein 1α [MIP-1α]) on immune phenotype and protection against lethal challenge with herpes simplex virus type 2 (HSV-2). We observed that coinjection with IL-8 and RANTES plasmid DNAs dramatically enhanced antigen-specific Th1 type cellular immune responses and protection from lethal HSV-2 challenge. This enhanced protection appears to be mediated by CD4+ T cells, as determined by in vitro and in vivo T-cell subset deletion. Thus, IL-8 and RANTES cDNAs used as DNA vaccine adjuvants drive antigen-specific Th1 type CD4+ T-cell responses, which result in reduced HSV-2-derived morbidity, as well as reduced mortality. However, coinjection with DNAs expressing MCP-1, IP-10, and MIP-1α increased mortality in the challenged mice. Chemokine DNA coinjection also modulated its own production as well as the production of cytokines. These studies demonstrate that chemokines can dominate and drive immune responses with defined phenotypes, playing an important role in the generation of protective antigen-specific immunity.
Lyme disease is clinically and histologically characterized by strong inflammatory reactions that contrast the paucity of spirochetes at lesional sites, indicating that borreliae induce mechanisms that amplify the inflammatory response. To reveal the underlying mechanisms of chemoattraction and activation of responding leukocytes, we investigated the induction of chemokines in human monocytes exposed to Borrelia burgdorferi by a dose-response and kinetic analysis. Lipopolysaccharide (LPS) derived from Escherichia coli was used as a positive control stimulus. The release of the CXC chemokines interleukin-8 (IL-8) and GRO-alpha and the CC chemokines MIP-1alpha, MCP-1, and RANTES was determined by specific enzyme-linked immunosorbent assays, and the corresponding gene expression patterns were determined by Northern blot analysis. The results showed a rapid and strong borrelia-inducible gene expression which was followed by the release of chemokines with peak levels after 12 to 16 h. Spirochetes and LPS were comparably effective in stimulating IL-8, GRO-alpha, MCP-1, and RANTES expression, whereas MIP-1alpha production preceded and exceeded chemokine levels induced by LPS. Unlike other bacteria, the spirochetes themselves did not bear or release factors with intrinsic chemotactic activity for monocytes or neutrophils. Thus, B. burgdorferi appears to be a strong inducer of chemokines which may, by the attraction and activation of phagocytic leukocytes, significantly contribute to inflammation and tissue damage observed in Lyme disease.
Delayed cord clamping may be beneficial in very preterm and low birth weight infants.
A randomized unmasked controlled trial
The study was performed in three centers of the NICHD Neonatal Research Network
Delayed cord clamping in very preterm and very low birth weight infants will result in an increase in hematocrit at 4 hours of age.
Infants with a gestational age of 24-28 weeks were randomized into early (< 10 seconds) or delayed (30-45 seconds) cord clamping. The primary outcome was venous hematocrit at 4 hours of age. Secondary outcomes included delivery room management, selected neonatal morbidities and the need for blood transfusion during the infants’ hospital stay.
Thirty three infants were randomized: 17 to the immediate cord clamping (ICC, cord clamped at 7.9 ± 5.2 seconds, m±SD) and 16 to the delayed cord clamping (DCC, cord clamped at 35.2 ± 10.1 seconds) group. The hematocrit was higher in the DCC group (45 ± 8 versus 40 ± 5%, p<0.05). The frequency of events during delivery room resuscitation was almost identical between the two groups. There was no difference in hourly mean arterial blood pressure during the first 12 hours of life, there was a trend in the difference in the incidence of selected neonatal morbidities, hematocrit at 2, 4 and 6 weeks as well as the need for transfusion, but none of the differences was statistically significant
A higher hematocrit is achieved by delayed cord clamping in very low birth weight infants suggesting effective placental transfusion.
Forty one preterm infants (birth weight < 1500 g) were studied by daily Doppler echocardiography for the first week of life to examine the effect of a haemodynamically significant ductus arteriosus (HSDA) on systemic blood pressure. Hourly records of blood pressure were averaged for each infant to produce a 24 hour mean value and the infants were then allocated to groups according to whether, by echocardiographic criteria, there was a HSDA on that day. In infants from 1000 to 1500 g the differences in all parameters of blood pressure between those with and without a HSDA were not significant. In infants < 1000 g the mean blood pressure was significantly less in the infants with a HSDA throughout the first week of life. Systolic blood pressure was reduced by as much as diastolic blood pressure and as a result the pulse pressure did not differ. Infants < 1000 g with a HSDA were given more plasma and a greater number received inotropic support. Gestational age, respiratory disease severity, and complication rates did not differ between those with and without a HSDA. The possibility of a clinically silent HSDA should be considered before large amounts of plasma volume expanders are given to treat hypotension in infants < 1000 g.
The potential negative impact of early blood oxygenation on development of specific cognitive and motor outcomes in children born at very low birth weight (VLBW; 1000 − 1500g) has not been examined even though these infants are exposed to varying durations and amounts of oxygen as part of their neonatal care. While this is the largest group of preterm infants, they receive much less research attention than extremely low birth weight infants (ELBW < 1000g).
Although neonatologists are questioning the routine use of oxygen therapy for all neonates, research has focused primarily on the more medically fragile ELBW infants. To date there are no systematic studies available to guide decision making for oxygen supplementation for a large segment of the preterm infant population. The aim of the present study was to determine if there is an association between blood oxygenation in the first four hours of life and specific cognitive and motor skills in preterm infants with acute respiratory disorders but no severe intracranial insult using a selected cohort from a longitudinal study children recruited in 1991 and 1992 designed to examine the role of biological immaturity as defined by gestational age and parenting in development. From this cohort, 55 children had acute respiratory disorders without severe intracranial insult. Of these, 35 children had at least one partial pressure of oxygen obtained from arterial blood (PaO2) during the first four hours of life as part of their clinical care. Higher early PaO2 values were associated with lower impulse control and attention skills in the elementary school age period. Models that examined for relations between PaO2 values that also included birth weight and parenting quality across the first year of life revealed that higher PaO2 remained associated with impulse control but not attention skills. Birth weight was not associated with any outcomes. These results suggest that hyperoxia may be a risk factor for developmental problems that are not expressed until school age.
very low birth weight; acute respiratory disorders; child development
Invasive candidiasis is a leading cause of infection-related morbidity and mortality in extremely low-birth-weight (<1000 g) infants. We quantify risk factors predicting infection in high-risk premature infants and compare clinical judgment with a prediction model of invasive candidiasis.
The study involved a prospective observational cohort of infants <1000 g birth weight at 19 centers of the NICHD Neonatal Research Network. At each sepsis evaluation, clinical information was recorded, cultures obtained, and clinicians prospectively recorded their estimate of the probability of invasive candidiasis. Two models were generated with invasive candidiasis as their outcome: 1) potentially modifiable risk factors and 2) a clinical model at time of blood culture to predict candidiasis.
Invasive candidiasis occurred in 137/1515 (9.0%) infants and was documented by positive culture from ≥ 1 of these sources: blood (n=96), cerebrospinal fluid (n=9), urine obtained by catheterization (n=52), or other sterile body fluid (n=10). Mortality was not different from infants who had positive blood culture compared to those with isolated positive urine culture. Incidence varied from 2–28% at the 13 centers enrolling ≥ 50 infants. Potentially modifiable risk factors (model 1) included central catheter, broad-spectrum antibiotics (e.g., third-generation cephalosporins), intravenous lipid emulsion, endotracheal tube, and antenatal antibiotics. The clinical prediction model (model 2) had an area under the receiver operating characteristic curve of 0.79, and was superior to clinician judgment (0.70) in predicting subsequent invasive candidiasis. Performance of clinical judgment did not vary significantly with level of training.
Prior antibiotics, presence of a central catheter, endotracheal tube, and center were strongly associated with invasive candidiasis. Modeling was more accurate in predicting invasive candidiasis than clinical judgment.
Candidiasis; premature infant; risk factors
Chemokines play a pivotal role in the innate response to both bacterial and viral infections, and in mixed infections. To determine chemokine responses to Sindbis virus (SIN) in a co-infection model, peripheral blood mononuclear cells (PBMCs) derived from healthy volunteers were exposed to SIN in the presence and absence of lipopolysaccharide (LPS). Culture supernatants recovered at 2, 24, and 72 h post-exposure were evaluated for virus replication and analyzed for chemokines by ELISA. None of the PBMC cultures showed new virus release, GFP reporter expression, or viral RNA synthesis. While SIN had little effect on the induction of IL-8 and RANTES, the chemokines MCP-1, MIP1-α (p < 0.001), and MIP1-β (p < 0.0004) were drastically upregulated by SIN as well as LPS. Both live and UV-inactivated SIN induced secretion of IP-10 and I-TAC. Although LPS did not induce release of IP-10, it sharply inhibited (p = 0.004) SIN-mediated IP-10 secretion. On the contrary, the release of SLC was blocked by SIN. The adjuvant activity of IP-10, its antiangiogenic function, and antagonism between SIN and LPS for the release of select chemokines may be useful in understanding the pathogenesis of mixed infections, cross-talk between cellular pathways, and may have applications in cancer and sepsis.
BACKGROUND/AIMS—Chemokines are a family of low molecular weight cytokines that attract and activate leucocytes. The CC chemokines act on eosinophils, basophils, monocytes, and lymphocytes, suggesting that they play an important part in allergic diseases. The aims of this study were to investigate the expression of the CC chemokines, RANTES, eotaxin, monocyte chemotactic protein (MCP) 1, MCP-2, and MCP-3 in the conjunctiva of patients with vernal keratoconjunctivitis (VKC) and to determine the cellular source of these chemokines.
METHODS—Conjunctival biopsy specimens from nine subjects with active VKC, and six control subjects were studied by immunohistochemical techniques using a panel of monoclonal and polyclonal antibodies directed against RANTES, eotaxin, MCP-1, MCP-2, and MCP-3. The phenotype of inflammatory cells expressing chemokines was examined by sequential double immunohistochemistry.
RESULTS—In the normal conjunctiva, superficial epithelial cells showed a constitutive, weak cytoplasmic expression of eotaxin. Few inflammatory cells in the perivascular areas expressed RANTES, MCP-1, MCP-2, and MCP-3. In VKC specimens, the epithelium showed intense cytoplasmic eotaxin staining in all cells, and cytoplasmic RANTES staining mainly in the superficial layers. Furthermore, RANTES and eotaxin were expressed on the vascular endothelium mainly in the upper substantia propria. Compared with normal controls, VKC specimens showed significantly more inflammatory cells expressing RANTES, eotaxin, MCP-1, and MCP-3 (p<0.001, 0.0028, 0.0092, and <0.001, respectively). In VKC specimens, the numbers of inflammatory cells expressing RANTES were significantly higher than the numbers of inflammatory cells expressing eotaxin, MCP-1, and MCP-2 (all p values <0.001). Colocalisation studies revealed that the majority of inflammatory cells expressing chemokines were CD68 positive monocytes/macrophages.
CONCLUSIONS—These results demonstrate an increase in the expression of RANTES, eotaxin, MCP-1, and MCP-3 in the conjunctiva of patients with VKC compared with control subjects. These data suggest a potential role for these chemokines in the pathogenesis of VKC. Antagonists of chemokine receptors may provide new therapeutic modalities in VKC.
Matrix metalloproteinases (MMPs) are involved in remodeling of the extracellular matrix (ECM) during pregnancy and parturition. Aberrant ECM degradation by MMPs or an imbalance between MMPs and their tissue inhibitors (TIMPs) have been implicated in the pathogenesis of preterm labor, however few studies have investigated MMPs or TIMPs in maternal serum. Therefore, the purpose of this study was to determine serum concentrations of MMP-3, MMP-9 and all four TIMPs as well as MMP:TIMP ratios during term and preterm labor.
A case control study with 166 singleton pregnancies, divided into four groups: (1) women with preterm birth, delivering before 34 weeks (PTB); (2) gestational age (GA) matched controls, not in preterm labor; (3) women at term in labor and (4) at term not in labor. MMP and TIMP concentrations were measured using Luminex technology.
MMP-9 and TIMP-4 concentrations were higher in women with PTB vs. GA matched controls (resp. p = 0.01 and p<0.001). An increase in MMP-9:TIMP-1 and MMP-9:TIMP-2 ratio was observed in women with PTB compared to GA matched controls (resp. p = 0.02 and p<0.001) as well as compared to women at term in labor (resp. p = 0.006 and p<0.001). Multiple regression results with groups recoded as three key covariates showed significantly higher MMP-9 concentrations, higher MMP-9:TIMP-1 and MMP-9:TIMP-2 ratios and lower TIMP-1 and -2 concentrations for preterm labor. Significantly higher MMP-9 and TIMP-4 concentrations and MMP-9:TIMP-2 ratios were observed for labor.
Serum MMP-9:TIMP-1 and MMP-9:TIMP-2 balances are tilting in favor of gelatinolysis during preterm labor. TIMP-1 and -2 concentrations were lower in preterm gestation, irrespective of labor, while TIMP-4 concentrations were raised in labor. These observations suggest that aberrant serum expression of MMP:TIMP ratios and TIMPs reflect pregnancy and labor status, providing a far less invasive method to determine enzymes essential in ECM remodeling during pregnancy and parturition.
Chemokines are a family of low-molecular-weight proinflammatory cytokines that stimulate recruitment of leukocytes. The chemokines interleukin-8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1) are relatively specific chemoattractants for neutrophils and monocytes, respectively. Chemokine expression contributes to the presence of different leukocyte populations observed in normal and pathologic states. In the present studies, peripheral blood mononuclear cells (PBMC) were stimulated by microbes (Candida albicans, Streptococcus mutans, Porphyromonas gingivalis, and Actinobacillus actinomycetemcomitans) selected based upon their importance as oral pathogens. IL-8 and MCP-1 gene expression and protein release were determined by Northern blot (RNA blot) analysis and enzyme-linked immunosorbent assay. C. albicans, P. gingivalis, and A. actinomycetemcomitans induced high levels of production of both MCP-1 and IL-8. S. mutans was a strong inducer of MCP-1, but it did not stimulate significant production of IL-8. C. albicans, S. mutans, and A. actinomycetemcomitans were 500 to 5,000 times more potent than P. gingivalis in terms of MCP-1 production. In general, the microbe-to-PBMC ratios required for maximum gene expression of MCP-1 were lower than those for IL-8. However, for actual protein release of MCP-1 versus IL-8, differences in the effects of various microbe concentrations were observed only for A. actinomycetemcomitans. These results demonstrate that different oral pathogens induce specific dose-dependent patterns of chemokine gene expression and release. Such patterns may help explain the immunopathology of oral infections, particularly with regard to inflammatory leukocyte recruitment.
Leukocyte emigration possibly requires dynamic regulation of integrin adhesiveness for endothelial and extracellular matrix ligands. Adhesion assays on purified vascular cell adhension molecule (VCAM)-1, fibronectin, and fibronectin fragments revealed distinct kinetic patterns for the regulation of very late antigen (VLA)-4 (alpha 4 beta 1) and VLA-5 (alpha 5 beta 1) avidity by the CC chemokines monocyte inflammatory protein (MIP)-1 alpha, RANTES (regulated on activation, normal T expressed and secreted), or monocyte chemoattractant protein (MCP)-1 in monocytes. CC chemokines induced early activation and subsequent deactivation of VLA-4, whereas upregulation of VLA-5 avidity occurred later and persisted. Controlled detachment assays in shear flow suggested that adhesive strength of VLA-4 for VCAM-1 or the 40-kD fragment of fibronectin (FN40) is more rapidly increased and subsequently reduced by MCP-1 than by MIP-1 alpha, and confirmed late and sustained activation of the adhesive strength of VLA-5 for the 120- kD fragment of fibronectin (FN120). Mn2+ or the stimulating beta 1 mAb TS2/16 strongly and stably enhanced monocyte binding to VCAM-1 or fibronectin, and locked beta 1 integrins in a high avidity state, which was not further modulated by CC chemokines. Mn2+ and mAb TS2/16 inhibited CC chemokine-induced transendothelial migration, particularly chemotaxis across stimulated endothelium that involved VLA-4 and VCAM- 1. VLA-4 on Jurkat cells is of constitutively high avidity and interfered with migration across barriers expressing VCAM-1. Low but not high site densities of VCAM-1 or FN40 promoted, while FN120 impaired, beta 1 integrin-dependent monocyte chemotaxis to MCP-1 across filters coated with these substrates. Thus, we show that CC chemokines can differentially and selectively regulate avidity of integrins sharing common beta subunits. Transient activation and deactivation of VLA-4 may serve to facilitate transendothelial diapedesis, whereas late and prolonged activation of VLA-5 may mediate subsequent interactions with the basement membrane and extracellular matrix.