Host response to malaria during pregnancy: placental monocyte recruitment is associated with elevated beta chemokine expression

Malaria during pregnancy is associated with poor birth outcomes, particularly low birth weight. Recently, monocyte infiltration into the placental intervillous space has been identified as a key risk factor for low birth weight. However, the malaria-induced chemokines involved in recruiting and activating placental monocytes have not been identified. In this study, we determined which chemokines are elevated during placental malaria infection and the association between chemokine expression and placental monocyte infiltration. Placental malaria infection was associated with elevations in mRNA expression of three beta chemokines, macrophage-inflammatory protein 1 (MIP-1) alpha (CCL3), monocyte chemoattractant protein 1 (MCP-1; CCL2), and I-309 (CCL1), and one alpha chemokine, IL-8 (CXCL8); all correlated with monocyte density in the placental intervillous space. Placental plasma concentrations of MIP-1 alpha and IL-8 were increased in women with placental malaria and were associated with placental monocyte infiltration. By immunohistochemistry, we localized placental chemokine production in malaria-infected placentas: some but not all hemozoin-laden maternal macrophages produced MIP-1 beta and MCP-1, and fetal stromal cells produced MCP-1. In sum, local placental production of chemokines is increased in malaria, and may be an important trigger for monocyte accumulation in the placenta.     

Differential binding of chemokines to macrophages and neutrophils in the human inflamed synovium

In chronic inflammatory foci, such as the rheumatoid joint, there is enhanced recruitment of phagocytes from the blood into the tissues. Chemokines are strongly implicated in directing the migration of these cells, although little is known regarding the chemokine receptors that could mediate their chemotaxis into the joint tissue. Therefore the objective of the study was to identify chemokine binding sites on macrophages and neutrophils within the rheumatoid synovium using radiolabeled ligand binding and in situ autoradiography. Specific binding sites for CCL3 (macrophage inflammatory protein-1alpha), CCL5 (RANTES), CCL2 (monocyte chemoattractant protein-1) and CXCL8 (IL-8) were demonstrated on CD68+ macrophages in the subintimal and intimal layers. The number and percentage of intimal cells that bound chemokines were greater in inflamed regions compared to noninflamed regions. The intensity of intimal binding varied between chemokines with the rank order, CCL3 > CCL5 > CCL2 > CXCL8. Neutrophils throughout the synovium bound CXCL8 but did not show any signal for binding CCL2, CCL3 or CCL5. Immunohistochemistry showed that both CXCR1 and CXCR2 are expressed by macrophages and neutrophils in the rheumatoid and nonrheumatoid synovia, suggesting that both of these receptors are responsible for the CXCL8 binding. The chemokine binding sites described on phagocytes may be involved in the migration of these cells into the inflamed joint.     

The Toll-like receptor 5 stimulus bacterial flagellin induces maturation and chemokine production in human dendritic cells

Toll-like receptors (TLRs) are pattern recognition receptors that serve an important function in detecting pathogens and initiating inflammatory responses. Upon encounter with foreign Ag, dendritic cells (DCs) go through a maturation process characterized by an increase in surface expression of MHC class II and costimulatory molecules, which leads to initiation of an effective immune response in naive T cells. The innate immune response to bacterial flagellin is mediated by TLR5, which is expressed on human DCs. Therefore, we sought to investigate whether flagellin could induce DC maturation. Immature DCs were cultured in the absence or presence of flagellin and monitored for expression of cell surface maturation markers. Stimulation with flagellin induced increased surface expression of CD83, CD80, CD86, MHC class II, and the lymph node-homing chemokine receptor CCR7. Flagellin stimulated the expression of chemokines active on neutrophils (IL-8/CXC chemokine ligand (CXCL)8, GRO-alpha/CXCL1, GRO-beta/CXCL2, GRO-gamma/CXCL3), monocytes (monocyte chemoattractant protein-1/CC chemokine ligand (CCL)2), and immature DCs (macrophage-inflammatory protein-1 alpha/CCL3, macrophage-inflammatory protein-1 beta/CCL4), but not chemokines active on effector T cells (IFN-inducible protein-10 kDa/CXCL10, monokine induced by IFN-gamma/CXCL9, IFN-inducible T cell alpha chemoattractant/CXCL11). However, stimulating DCs with both flagellin and IFN-inducible protein-10 kDa, monokine induced by IFN-gamma, and IFN-inducible T cell alpha chemoattractant expression, whereas stimulation with IFN-beta or flagellin alone failed to induce these chemokines. In functional assays, flagellin-matured DCs displayed enhanced T cell stimulatory activity with a concomitant decrease in endocytic activity. Finally, DCs isolated from mouse spleens or bone marrows were shown to not express TLR5 and were not responsive to flagellin stimulation. These results demonstrate that flagellin can directly stimulate human but not murine DC maturation, providing an additional mechanism by which motile bacteria can initiate an acquired immune response.     

Eotaxin/CCL11 suppresses IL-8/CXCL8 secretion from human dermal microvascular endothelial cells

The CC chemokine eotaxin/CCL11 is known to bind to the receptor CCR3 on eosinophils and Th2-type lymphocytes. In this study, we demonstrate that CCR3 is expressed on a subpopulation of primary human dermal microvascular endothelial cells and is up-regulated by TNF-alpha. We found that incubation of human dermal microvascular endothelial cells with recombinant eotaxin/CCL11 suppresses TNF-alpha-induced production of the neutrophil-specific chemokine IL-8/CXCL8. The eotaxin/CCL11-suppressive effect on endothelial cells was not seen on IL-1beta-induced IL-8/CXCL8 release. Eotaxin/CCL11 showed no effect on TNF-alpha-induced up-regulation of growth-related oncogene-alpha or IFN-gamma-inducible protein-10, two other CXC chemokines tested, and did not affect production of the CC chemokines monocyte chemoattractant protein-1/CCL2 and RANTES/CCL5, or the adhesion molecules ICAM-1 and E-selectin. These results suggest that eotaxin/CXCL11 is not effecting a general suppression of TNF-alphaR levels or signal transduction. Suppression of IL-8/CXCL8 was abrogated in the presence of anti-CCR3 mAb, pertussis toxin, and wortmannin, indicating it was mediated by the CCR3 receptor, G(i) proteins, and phosphatidylinositol 3-kinase signaling. Eotaxin/CCL11 decreased steady state levels of IL-8/CXCL8 mRNA in TNF-alpha-stimulated cells, an effect mediated in part by an acceleration of IL-8 mRNA decay. Eotaxin/CCL11 may down-regulate production of the neutrophil chemoattractant IL-8/CXCL8 by endothelial cells in vivo, acting as a negative regulator of neutrophil recruitment. This may play an important biological role in the prevention of overzealous inflammatory responses, aiding in the resolution of acute inflammation or transition from neutrophilic to mononuclear/eosinophilic inflammation.     

Monocyte chemoattractant protein-1--a major contributor to the inflammatory process associated with diabetes

There is evidence that strongly suggests that inflammation plays an important role in diabetes and cardiovascular diseases. The high glucose-induced inflammatory process is characterised by the cooperation of a complex network of inflammatory molecules such as cytokines, adhesion molecules, growth factors, and chemokines. Among the chemokine family, monocyte chemoattractant protein (MCP-1) is a potent chemotactic factor, which is upregulated at sites of inflammation being in control of leukocytes trafficking. Here, we review the current knowledge on MCP-1 and its regulation by high glucose level in vascular cells involved in diabetes-induced accelerated atherosclerosis. The signalling pathways involved in MCP-1 modulation by high glucose, the proximal signalling events that stimulate downstream effects and the role of this chemokine in the pathophysiology of diabetes and its complications, are discussed.     

Visualization of chemokine binding sites on human brain microvessels

The chemokines monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha) 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-alpha around human brain microvessels were revealed for the first time. Binding of labeled MCP-1 and MIP-1alpha 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-1alpha 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.     

Variability in chemokine-induced adhesion of human mesenchymal stromal cells

BACKGROUND AIMS. Intravenously applied mesenchymal stromal cells (MSC) are under investigation for numerous clinical indications. However, their capacity to activate shear stress-dependent adhesion to endothelial ligands is incompletely characterized. METHODS. Parallel-plate flow chambers were used to induce firm adhesion of MSC to integrin ligand vascular cell adhesion molecule (VCAM)-1. Human MSC were stimulated by chemokine (C-C motif) ligand (CCL15)/macrophage inflammatory protein (MIP-5), CCL19/MIP-3β chemokine (C-X-C motif) ligand (CXCL8)/interleukin (IL)-8, CXCL12/ stromal derived factor (SDF-1) or CXCL13/B lymphocyte chemoattractant (BLC). RESULTS. Two MSC isolates responded to three chemokines (either to CCL15, CCL19 and CXCL13, or to CCL19, CXCL12 and CXCL13), two isolates responded to two chemokines (to CCL15 and CCL19, or to CCL19 and CXCL13), and one isolate responded to CCL19 only. In contrast, all tested MSC isolates responded to selectins (P-selectin and E-selectin) or integrin ligand VCAM-1, as visualized by a velocity reduction under flow. CONCLUSIONS. Inter-individual variability of chemokine-induced integrin activation should be considered when evaluating human MSC as cellular therapies.     

Role of chemokines and formyl peptides in pneumococcal pneumonia-induced monocyte/macrophage recruitment

Host-derived chemoattractant factors are suggested to play crucial roles in leukocyte recruitment elicited by inflammatory stimuli in vitro and in vivo. However, in the case of acute bacterial infections, pathogen-derived chemoattractant factors are also present, and it has not yet been clarified how cross-talk between chemoattractant receptors orchestrates diapedesis of leukocytes in this context of complex chemoattractant arrays. To investigate the role of chemokine (host-derived) and formyl peptide (pathogen-derived) chemoattractants in leukocyte extravasation in life-threatening infectious diseases, we used a mouse model of pneumococcal pneumonia. We found an increase in mRNA expression of eight chemokines (RANTES, macrophage-inflammatory protein (MIP)-1alpha, MIP-1beta, MIP-2, IP-10, monocyte chemoattractant protein (MCP)-1, T cell activation 3, and KC) within the lungs during the course of infection. KC and MIP-2 protein expression closely preceded pulmonary neutrophil recruitment, whereas MCP-1 protein production coincided more closely than MIP-1alpha with the kinetics of macrophage infiltration. In situ hybridization of MCP-1 mRNA suggested that MCP-1 expression started at peribronchovascular regions and expanded to alveoli-facing epithelial cells and infiltrated macrophages. Interestingly, administration of a neutralizing Ab against MCP-1, RANTES, or MIP-1alpha alone did not prevent macrophage infiltration into infected alveoli, whereas combination of the three Abs significantly reduced macrophage infiltration without affecting neutrophil recruitment. The use of an antagonist to N-formyl peptides, N-t-Boc-Phe-D-Leu-Phe-D-Leu-Phe, reduced both macrophages and neutrophils significantly. These data demonstrate that a complex chemokine network is activated in response to pulmonary pneumococcal infection, and also suggest an important role for fMLP receptor in monocyte/macrophage recruitment in that model.     

Differential binding of chemokines to macrophages and neutrophils in the human inflamed synovium

In chronic inflammatory foci, such as the rheumatoid joint, there is enhanced recruitment of phagocytes from the blood into the tissues. Chemokines are strongly implicated in directing the migration of these cells, although little is known regarding the chemokine receptors that could mediate their chemotaxis into the joint tissue. Therefore the objective of the study was to identify chemokine binding sites on macrophages and neutrophils within the rheumatoid synovium using radiolabeled ligand binding and in situ autoradiography. Specific binding sites for CCL3 (macrophage inflammatory protein-1α), CCL5 (RANTES), CCL2 (monocyte chemoattractant protein-1) and CXCL8 (IL-8) were demonstrated on CD68⁺ macrophages in the subintimal and intimal layers. The number and percentage of intimal cells that bound chemokines were greater in inflamed regions compared to noninflamed regions. The intensity of intimal binding varied between chemokines with the rank order, CCL3 > CCL5 > CCL2 > CXCL8. Neutrophils throughout the synovium bound CXCL8 but did not show any signal for binding CCL2, CCL3 or CCL5.     

Modeling the early events of severe acute respiratory syndrome coronavirus infection in vitro

The clinical picture of severe acute respiratory syndrome (SARS) is characterized by pulmonary inflammation and respiratory failure, resembling that of acute respiratory distress syndrome. However, the events that lead to the recruitment of leukocytes are poorly understood. To study the cellular response in the acute phase of SARS coronavirus (SARS-CoV)-host cell interaction, we investigated the induction of chemokines, adhesion molecules, and DC-SIGN (dendritic cell-specific ICAM-3-grabbing nonintegrin) by SARS-CoV. Immunohistochemistry revealed neutrophil, macrophage, and CD8 T-cell infiltration in the lung autopsy of a SARS patient who died during the acute phase of illness. Additionally, pneumocytes and macrophages in the patient's lung expressed P-selectin and DC-SIGN. In in vitro study, we showed that the A549 and THP-1 cell lines were susceptible to SARS-CoV. A549 cells produced CCL2/monocyte chemoattractant protein 1 (MCP-1) and CXCL8/interleukin-8 (IL-8) after interaction with SARS-CoV and expressed P-selectin and VCAM-1. Moreover, SARS-CoV induced THP-1 cells to express CCL2/MCP-1, CXCL8/IL-8, CCL3/MIP-1alpha, CXCL10/IP-10, CCL4/MIP-1beta, and CCL5/RANTES, which attracted neutrophils, monocytes, and activated T cells in a chemotaxis assay. We also demonstrated that DC-SIGN was inducible in THP-1 as well as A549 cells after SARS-CoV infection. Our in vitro experiments modeling infection in humans together with the study of a lung biopsy of a patient who died during the early phase of infection demonstrated that SARS-CoV, through a dynamic interaction with lung epithelial cells and monocytic cells, creates an environment conducive for immune cell migration and accumulation that eventually leads to lung injury.     

Deficiency for the Chemokine Monocyte Chemoattractant Protein-1 Aggravates Tubular Damage after Renal Ischemia/Reperfusion Injury

Temporal expression of chemokines is a crucial factor in the regulation of renal ischemia/reperfusion (I/R) injury and repair. Beside their role in the migration and activation of inflammatory cells to sites of injury, chemokines are also involved in other processes such as angiogenesis, development and migration of stem cells. In the present study we investigated the role of the chemokine MCP-1 (monocyte chemoattractant protein-1 or CCL2), the main chemoattractant for monocytes, during renal I/R injury. MCP-1 expression peaks several days after inducing renal I/R injury coinciding with macrophage accumulation. However, MCP-1 deficient mice had a significant decreased survival and increased renal damage within the first two days, i.e. the acute inflammatory response, after renal I/R injury with no evidence of altered macrophage accumulation. Kidneys and primary tubular epithelial cells from MCP-1 deficient mice showed increased apoptosis after ischemia. Taken together, MCP-1 protects the kidney during the acute inflammatory response following renal I/R injury.     

Blockade of neurokinin-1 receptor attenuates CC and CXC chemokine production in experimental acute pancreatitis and associated lung injury

Accumulating evidence suggests the neuropeptide substance P (SP) and its receptor neurokinin-1 receptor (NK-1R) play a pivotal role in the pathogenesis of acute pancreatitis (AP). However, the mechanisms remain unclear. The present study investigated whether chemokines as proinflammatory molecules are involved in SP-NK-1R-related pathogenesis of this condition. We observed temporally and spatially selective chemokine responses in secretagogue caerulein-induced AP in mice. CC chemokines monocyte chemotactic protein (MCP)-1 and macrophage inflammatory protein-1alpha (MIP-1alpha) and CXC chemokine MIP-2 were elevated after AP induction. Time-dependent, tissue-specific analysis of their mRNA and protein expression suggested that they are early mediators in the condition and mediate local as well as systemic inflammatory responses. In contrast, another CC chemokine regulated on activation, T cells expressed and secreted (RANTES) was only involved in local pancreatic inflammation at a later stage of the disease. Either prophylactic or therapeutic treatment with a potent selective NK-1R antagonist CP-96,345 significantly suppressed caerulein-induced increase in MCP-1, MIP-1alpha, and MIP-2 expression but had no apparent effect on RANTES expression. The suppression effect of CP-96,345 on MCP-1, MIP-1alpha, and MIP-2 expression was concordantly demonstrated by immunohistochemistry, which, additionally, suggested that chemokine immunoreactivity was localized to acinar cells and the infiltrating leukocytes in the pancreas and alveolar macrophages, epithelial cells, and endothelial cells in the lungs. Our data suggest that SP, probably by acting via NK-1R on various chemokine-secreting cells in the pancreas and lungs, stimulates the release of chemokines that aggravate local AP and the development of its systemic sequelae.     

Regulated production and molecular diversity of human liver and activation-regulated chemokine/macrophage inflammatory protein-3 alpha from normal and transformed cells

Liver and activation-regulated chemokine (LARC), also designated macrophage inflammatory protein-3alpha (MIP-3alpha), Exodus, or CCL20, is a C-C chemokine that attracts immature dendritic cells and memory T lymphocytes, both expressing CCR6. Depending on the cell type, this chemokine was found to be inducible by cytokines (IL-1beta) and by bacterial, viral, or plant products (including LPS, dsRNA, and PMA) as measured by a specific ELISA. Although coinduced with monocyte chemotactic protein-1 (MCP-1) and IL-8 by dsRNA, measles virus, and IL-1beta in diploid fibroblasts, leukocytes produced LARC/MIP-3alpha only in response to LPS. However, in myelomonocytic THP-1 cells LARC/MIP-3alpha was better induced by phorbol ester, whereas in HEp-2 epidermal carcinoma cells IL-1beta was the superior inducer. The production levels of LARC/MIP-3alpha (1-10 ng/ml) were, on the average, 10- to 100-fold lower than those of IL-8 and MCP-1, but were comparable to those of other less abundantly secreted chemokines. Natural LARC/MIP-3alpha protein isolated from stimulated leukocytes or tumor cell lines showed molecular diversity, in that NH(2)- and COOH-terminally truncated forms were purified and identified by amino acid sequence analysis and mass spectrometry. In contrast to other chemokines, including MCP-1 and IL-8, the natural processing did not affect the calcium-mobilizing capacity of LARC/MIP-3alpha through its receptor CCR6. Furthermore, truncated natural LARC/MIP-3alpha isoforms were equally chemotactic for lymphocytes as intact rLARC/MIP-3alpha. It is concluded that in addition to its role in homeostatic trafficking of leukocytes, LARC/MIP-3alpha can function as an inflammatory chemokine during host defense.     

Substance P treatment stimulates chemokine synthesis in pancreatic acinar cells via the activation of NF-kappaB

Acinar cell injury early in acute pancreatitis leads to a local inflammatory reaction and to the subsequent systemic inflammatory response, which may result in multiple organ dysfunction and death. Inflammatory mediators, including chemokines and substance P (SP), are known to play a crucial role in the pathogenesis of acute pancreatitis. It has been shown that pancreatic acinar cells produce the chemokine monocyte chemoattractant protein-1 (MCP-1) in response to caerulein hyperstimulation, demonstrating that acinar-derived MCP-1 is an early mediator of inflammation in acute pancreatitis. Similarly, SP levels in the pancreas and pancreatic acinar cell expression of neurokinin-1 receptor, the primary receptor for SP, are both increased during secretagogue-induced experimental pancreatitis. This study aims to examine the functional consequences of exposing mouse pancreatic acinar cells to SP and to determine whether it leads to proinflammatory signaling, such as production of chemokines. Exposure of mouse pancreatic acini to SP significantly increased synthesis of MCP-1, macrophage inflammatory protein-1alpha (MIP-1alpha), as well as MIP-2. Furthermore, SP also increased NF-kappaB activation. The stimulatory effect of SP was specific to chemokine synthesis through the NF-kappaB pathway, since the increase in chemokine production was completely attenuated when pancreatic acini were pretreated with the selective NF-kappaB inhibitor NF-kappaB essential modulator-binding domain peptide. This study shows that SP-induced chemokine synthesis in mouse pancreatic acinar cells is NF-kappaB dependent.     

Chemokines and their receptors in the brain: pathophysiological roles in ischemic brain injury

Chemokines constitute a large family of structurally-related small cytokines originally identified as factors regulating the migration of leukocytes in inflammatory and immune responses. Production of chemokines and their receptors in the brain has been reported under various pathological conditions. We revealed that mRNA expression for monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha (MIP-1alpha), members of the CC chemokines, was induced in the rat brain after focal cerebral ischemia, and that intracerebroventricular injection of viral macrophage inflammatory protein-II (vMIP-II), a broad-spectrum chemokine receptor antagonist, reduced infarct volume in a dose-dependent manner. These findings suggest that brain chemokines are involved in ischemic injury, and that chemokine receptors are potential targets for therapeutic intervention in stroke. Another potential target to suppress the harmful effect of chemokines is the signal transmission system(s) regulating the chemokine production. However, very little is known about how the production of chemokines is regulated in the ischemic brain. We examined the induction of MCP-1 production by excitotoxic injury via activation of NMDA receptors in the cortico-striatal slice cultures, and found that excitotoxic injury induced MCP-1 production in the slice culture. Almost all of the MCP-1 immunoreactivity was located on astrocytes. On the other hand, NMDA-treatment failed to increase the MCP-1 production in the enriched astrocyte cultures, indicating that NMDA dose not directly act on astrocytes. Some signal(s) is likely sent from the injured neurons to astrocytes to induce the MCP-1 production. These results showed that organotypic slice cultures are useful to investigate the molecular mechanism regulating the chemokine production in the injured brain.     

Citrullination of TNF-α by peptidylarginine deiminases reduces its capacity to stimulate the production of inflammatory chemokines

Citrullination, a posttranslational modification (PTM) recently discovered on inflammatory chemokines such as interleukin-8 (IL-8/CXCL8) and interferon-γ-inducible protein-10 (IP-10/CXCL10), seriously influences their biological activity. Citrullination or the deimination of arginine to citrulline is dependent on peptidylarginine deiminases (PADs) and has been linked to autoimmune diseases such as multiple sclerosis (MS) and rheumatoid arthritis (RA). Chemokines are to date the first identified PAD substrates with receptor-mediated biological activity. We investigated whether cytokines that play a crucial role in RA, like interleukin-1β (IL-1β) and tumor necrosis factor-alpha (TNF-α), may be citrullinated by PAD and whether such a PTM influences the biological activity of these cytokines. IL-1β and TNF-α were first incubated with PAD in vitro and the occurrence of citrullination was examined by Edman degradation and a recently developed detection method for citrullinated proteins. Both techniques confirmed that human TNF-α, but not IL-1β, was citrullinated by PAD. Citrullination of TNF-α reduced its potency to stimulate chemokine production in vitro on human primary fibroblasts. Concentrations of the inflammatory chemokines CXCL8, CXCL10 and monocyte chemotactic protein-1 (MCP-1/CCL2) were significantly lower in supernatants of fibroblasts induced with citrullinated TNF-α compared to unmodified TNF-α. However, upon citrullination TNF-α retained its capacity to induce apoptosis/necrosis of mononuclear cells, its binding potency to Infliximab and its ability to recruit neutrophils to the peritoneal cavity of mice.     

Effect of vitamin D(3) on chemokine expression in pulmonary tuberculosis

1,25 Dihydroxy vitamin D(3) (vitamin D(3)) is an immunomodulator and its deficiency has been associated with susceptibility to tuberculosis. We have studied the immunoregulatory role of vitamin D(3) on various chemokine expression in pulmonary tuberculosis. Peripheral blood mononuclear cells obtained from 21 pulmonary tuberculosis (PTB) patients and 24 healthy controls (HCs) were cultured for 48h with culture filtrate antigen (CFA) of Mycobacterium tuberculosis with or without vitamin D(3) at a concentration 1×10(-7)M. The relative mRNA expression of monocyte chemoattractant protein-1 (MCP-1, CCL2), macrophage inflammatory protein-1α (MIP-1α, CCL3), macrophage inflammatory protein-1β (MIP-1β, CCL4), and regulated upon-activation, normal T cell-expressed and secreted (RANTES, CCL5) and IFN-γ inducible protein-10 (IP-10, CXCL10) chemokines were estimated from 48h old macrophages using real-time polymerase chain reaction (RT-PCR). The culture supernatants were used to estimate the various chemokines including monokine induced by IFN-γ (MIG, CXCL9) levels using cytometric bead array. In HCs, vitamin D(3) significantly suppressed the MCP-1 mRNA expression of CFA stimulated cells (p=0.0027), while no such effect was observed in PTB patients. Vitamin D(3) showed no significant effect on MIP-1α, MIP-1β and RANTES in both the study groups. The CFA induced IP-10 mRNA and protein expression was significantly suppressed by vitamin D(3) in both the study groups (p<0.05). A similar suppressive effect of vitamin D(3) was observed with MIG protein in healthy controls (p=0.0029) and a trend towards a suppression was observed in PTB patients. The suppressive effect of vitamin D(3) is more prominent in CXC chemokines rather than CC chemokines. This suggests that vitamin D(3) may down regulate the recruitment and activation of T-cells through CXC chemokines at the site of infection and may act as a potential anti-inflammatory agent.     

G-protein-coupled receptor independent, immunomodulatory properties of chemokine CXCL9

Certain chemokines possess anti-angiogenic and antibacterial activity, in addition to their ability to recruit leukocytes. Herein, we demonstrate that CXCL9/MIG induces the expression, by a monocytic cell line and peripheral blood mononuclear cells, of a variety of chemokines including CXCL8/IL-8, CCL3/MIP-1α, CCL4/MIP-1β, CCL2/MCP-1 in a pertussis toxin insensitive manner. Similarly, another cationic chemokine CCL20/MIP-3α, but not the non-cationic chemokines CCL2 or CCL3, stimulated monocytic cells to produce substantial amounts of CXCL8 and CCL3. Microarray experiments demonstrated that CXCL9, but not CCL2, induced the expression of hundreds of genes, many of which have known or proposed immunomodulatory functions. Induction of CXCL8 required the p38 and ERK1/2 mitogen-activated protein kinases but not NFκB, JAK-STAT or JNK signaling pathways. These results collectively demonstrate that CXCL9 has immunomodulatory functions that are not mediated through a G-protein coupled receptor and may possess additional roles in host defenses against infection.