Serum and CSF levels of MCP-1 and IP-10 in multiple sclerosis patients with acute and stable disease and undergoing immunomodulatory therapies

Chemokine-mediated cell migration into the central nervous system in progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) has been associated with different forms of immune compromise. This study analyzes the chemokine signals and attracted immune cells in cerebrospinal fluid (CSF) during PML to define immune cell subpopulations relevant for the PML immune response. In addition to chemokines that indicate a general state of inflammation, like CCL5 and CXCL10, the CSF of PML patients specifically contains CCL2 and CCL4. Single-cell transcriptomics of CSF cells suggests an enrichment of distinct CD4+ and CD8+ T cells expressing chemokine receptors CCR2, CCR5, and CXCR3, in addition to ITGA4 and the genetic PML risk genes STXBP2 and LY9. This suggests that specific immune cell subpopulations migrate into the central nervous system to mitigate PML, and their absence might coincide with PML development. Monitoring them might hold clues for PML risk, and boosting their recruitment or function before therapeutic immune reconstitution might improve its risk-benefit ratio.

The brain cytokine orchestra in multiple sclerosis: from neuroinflammation to synaptopathology

The central nervous system (CNS) is finely protected by the blood-brain barrier (BBB). Immune soluble factors such as cytokines (CKs) are normally produced in the CNS, contributing to physiological immunosurveillance and homeostatic synaptic scaling. CKs are peptide, pleiotropic molecules involved in a broad range of cellular functions, with a pivotal role in resolving the inflammation and promoting tissue healing. However, pro-inflammatory CKs can exert a detrimental effect in pathological conditions, spreading the damage. In the inflamed CNS, CKs recruit immune cells, stimulate the local production of other inflammatory mediators, and promote synaptic dysfunction. Our understanding of neuroinflammation in humans owes much to the study of multiple sclerosis (MS), the most common autoimmune and demyelinating disease, in which autoreactive T cells migrate from the periphery to the CNS after the encounter with a still unknown antigen. CNS-infiltrating T cells produce pro-inflammatory CKs that aggravate local demyelination and neurodegeneration. This review aims to recapitulate the state of the art about CKs role in the healthy and inflamed CNS, with focus on recent advances bridging the study of adaptive immune system and neurophysiology.

CXCL10 Is Associated with Increased Cerebrospinal Fluid Immune Cell Infiltration and Disease Duration in Multiple Sclerosis

BACKGROUND

Cerebrospinal fluid (CSF) is an important sampling site for putative biomarkers and contains immune cells. CXCL10 is a multiple sclerosis (MS)-relevant chemokine that is present in the injured central nervous system and recruits CXCR3+ immune cells toward injured tissues.

OBJECTIVE

Perform a comprehensive evaluation to determine a potential relationship between CXCL10 and various immune cell subsets in the CNS of MS and control cases.

METHODS

In MS and control cases, CXCL10 was measured in the CSF and plasma by ELISA. Immune cells within both the CSF and peripheral blood were quantified by flow cytometry.

RESULTS

Compared to non-inflammatory neurological disease (NIND) cases, MS cases had significantly higher CXCL10 in CSF (p = 0.021); CXCL10 was also correlated with total cell numbers in CSF (p = 0.04) and T cell infiltrates (CD3+, p = 0.01; CD4+, p = 0.01; CD8+, p = 0.02); expression of CXCR3 on peripheral immune cell subsets was not associated with CSF CXCL10.

CONCLUSIONS

Elevated levels of CXCL10 in the CSF of MS cases are associated with increased T cells but appear to be independent of peripheral CXCR3 expression. These results support the importance of elevated CXCL10 in MS and suggest the presence of an alternative mechanism of CXCL10 outside of solely influencing immune cell trafficking.

Central and Peripheral Inflammation in Mild Cognitive Impairment in the Context of Alzheimer's Disease

Mild cognitive impairment (MCI) is characterized by an abnormal decline in mental and cognitive function compared with normal cognitive aging. It is an underlying condition of Alzheimer's disease (AD), an irreversible neurodegenerative disease. In recent years, neuroinflammation has been investigated as a new leading target that contributes to MCI progression into AD. Understanding the mechanism underlying inflammatory processes involved in the early onset of the disease could help find a safe and effective way to diagnose and treat patients. In this article, we assessed over twenty different blood and cerebrospinal fluid (CSF) inflammatory biomarker concentrations with immunoassay methods in patients with MCI (mild cognitive impairment), non-impaired control (NIC), and serum healthy control (HC). We performed group comparisons and analyzed in-group correlations between the biomarkers. We included 107 participants (mean age: 64.7 ± 7.8, women: 58.9%). CSF osteopontin and YKL-40 were significantly increased in the MCI group, whereas serum C-reactive protein and interleukin-6 were significantly higher (p < 0.001) in the NIC group compared with the MCI and HC groups. Stronger correlations between interleukin-1β and inflammasome markers were observed in the serum of the MCI group. We confirmed specific inflammatory activation in the central nervous system and interleukin-1β pathway upregulation in the serum of the MCI cohort.

Immune profiling in multiple sclerosis: a single-center study of 65 cytokines, chemokines, and related molecules in cerebrospinal fluid and serum

Introduction

The understanding of the pathophysiology of multiple sclerosis (MS) has evolved alongside the characterization of cytokines and chemokines in cerebrospinal fluid (CSF) and serum. However, the complex interplay of pro- and anti-inflammatory cytokines and chemokines in different body fluids in people with MS (pwMS) and their association with disease progression is still not well understood and needs further investigation. Therefore, the aim of this study was to profile a total of 65 cytokines, chemokines, and related molecules in paired serum and CSF samples of pwMS at disease onset.

Methods

Multiplex bead-based assays were performed and baseline routine laboratory diagnostics, magnetic resonance imaging (MRI), and clinical characteristics were assessed. Of 44 participants included, 40 had a relapsing-remitting disease course and four a primary progressive MS.

Results

There were 29 cytokines and chemokines that were significantly higher in CSF and 15 in serum. Statistically significant associations with moderate effect sizes were found for 34 of 65 analytes with sex, age, CSF, and MRI parameters and disease progression.

Discussion

In conclusion, this study provides data on the distribution of 65 different cytokines, chemokines, and related molecules in CSF and serum in newly diagnosed pwMS.

Urokinase, CX3CL1, CCL2, TRAIL and IL-18 induced by interferon-β treatment

OBJECTIVE

To identify serum proteins associated with MS and affected by interferon beta treatment.

METHODS

Plasma samples from 29 untreated relapsing-remitting MS patients and 15 healthy controls were investigated with a multiplexed panel containing 92 proteins related to inflammation. Follow-up samples were available from 13 patients at 1 and 3 months after initiation of treatment with interferon beta-1a.

RESULTS

Ten proteins were differentially expressed in MS patients. Five of these were altered by treatment with IFN-β 1a: uPA, CX3CL1, CCL2, TRAIL and IL18.

CONCLUSION

CCL2 and TRAIL were confirmed to be modulated with interferon beta treatment in MS. As novel findings, we now report that uPA and CX3CL1 were differentially expressed in MS and increased after IFN-beta-1a treatment. Conflicting results have been reported on how interferon beta affects IL-18.

Blood Serum Cytokines in Patients with Subacute Spinal Cord Injury: A Pilot Study to Search for Biomarkers of Injury Severity

Background. Despite considerable interest in the search for a spinal cord injury (SCI) therapy, there is a critical need to develop a panel of diagnostic biomarkers to determine injury severity. In this regard, there is a requirement for continuing research into the fundamental processes of neuroinflammatory and autoimmune reactions in SCI, identifying changes in the expression of cytokines. Methods. In this pilot study, an extended multiplex analysis of the cytokine profiles in the serum of patients at 2 weeks post-SCI (n = 28) was carried out, together with an additional assessment of neuron-specific enolase (NSE) and vascular endothelial growth factor (VEGF) levels by enzyme-linked immunosorbent assay. A total of 16 uninjured subjects were enrolled as controls. Results. The data obtained showed a large elevation of IFNγ (>52 fold), CCL27 (>13 fold), and CCL26 (>8 fold) 2 weeks after SCI. The levels of cytokines CXCL5, CCL11, CXCL11, IL10, TNFα, and MIF were different between patients with baseline American Spinal Injury Association Impairment Scale (AIS) grades of A or B, whilst IL2 (>2 fold) and MIP-3a (>6 fold) were significantly expressed in the cervical and thoracic regions. There was a trend towards increasing levels of NSE. However, the difference in NSE was lost when the patient set was segregated based on AIS group. Conclusions. Our pilot research demonstrates that serum concentrations of cytokines can be used as an affordable and rapid detection tool to accurately stratify SCI severity in patients.

A comprehensive review on the role of chemokines in the pathogenesis of multiple sclerosis

Multiple sclerosis (MS) as a chronic inflammatory disorder of the central nervous system (CNS) is thought to be caused by the abnormal induction of immune responses. Chemokines as molecules that can engage leukocytes into the location of inflammation, actively participate in the pathogenesis of MS. Several members of this family of chemo attractants have been shown to be dysregulated in the peripheral blood, cerebrospinal fluid or CNS lesions of MS patients. Studies in animal models of MS particularly experimental autoimmune encephalomyelitis have indicated the critical roles of chemokines in the pathophysiology of MS. In the current review, we summarize the data regarding the role of CCL2, CCL3, CCL4, CCL11, CCL20, CXCL1, CXCL2, CXCL8, CXCL10, CXCL12 and CXCL13 in the pathogenesis of MS.

CSF extracellular vesicles and risk of disease activity after a first demyelinating event

BACKGROUND

Extracellular vesicles (EVs), a recently described mechanism of cell communication, are released from activated microglial cells and macrophages and are a candidate biomarker in diseases characterized by chronic inflammatory process such as multiple sclerosis (MS).

METHODS

We explored cerebrospinal fluid extracellular vesicle (CSF EV) of myeloid origin (MEVs), cytokine and chemokine levels in patients with clinically isolated syndrome (CIS).

RESULTS

We found that CSF MEVs were significantly higher in CIS patients than in controls and were inversely correlated to CSF CCL2 levels. MEVs level were significantly associated with an shorter time to evidence of disease activity (hazard ratio: 1.01, 95% confidence interval: 1.00-1.02, p < 0.01) independently from other known prognostic markers.

CONCLUSION

After a first demyelinating event, CSF EVs may improve risk stratification of these patients and allow more targeted intervention strategies.

The role of chemokines and chemokine receptors in multiple sclerosis

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Summarize the study of the role of chemokines and their receptors in multiple sclerosis (MS) patients and MS animal models.

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Discuss their potential significance in inflammatory injury and repair of MS.

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Summarize the progress in the research of MS antagonists in recent years with chemokine receptors as targets.

Multiple sclerosis (MS) is a chronic inflammatory disease that is characterized by leukocyte infiltration and subsequent axonal damage, demyelinating inflammation, and formation of sclerosing plaques in brain tissue. The results of various studies in patients indicate that autoimmunity and inflammation make an important impact on the pathogenesis of MS. Chemokines are key mediators of inflammation development and cell migration, mediating various immune cell responses, including chemotaxis and immune activation, and are important in immunity and inflammation, therefore we focus on chemokines and their receptors in multiple sclerosis. In this article, we summarize the study of the role of prominent chemokines and their receptors in MS patients and MS animal modelsand discuss their potential significance in inflammatory injury and repair of MS. We have also summarized the progress in the treatment of multiple sclerosis antagonists in recent years with chemokine receptors as targets.

Palm Fruit Bioactives modulate human astrocyte activity in vitro altering the cytokine secretome reducing levels of TNFα, RANTES and IP-10

Neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease, are becoming more prevalent and an increasing burden on society. Neurodegenerative diseases often arise in the milieu of neuro-inflammation of the brain. Reactive astrocytes are key regulators in the development of neuro-inflammation. This study describes the effects of Palm Fruit Bioactives (PFB) on the behavior of human astrocytes which have been activated by IL-1β. When activated, the astrocytes proliferate, release numerous cytokines/chemokines including TNFα, RANTES (CCL5), IP-10 (CXCL10), generate reactive oxygen species (ROS), and express specific cell surface biomarkers such as the Intercellular Adhesion Molecule (ICAM), Vascular Cellular Adhesion Molecule (VCAM) and the Neuronal Cellular Adhesion Molecule (NCAM). Interleukin 1-beta (IL-1β) causes activation of human astrocytes with marked upregulation of pro-inflammatory genes. We show significant inhibition of these pro-inflammatory processes when IL-1β-activated astrocytes are exposed to PFB. PFB causes a dose-dependent and time-dependent reduction in specific cytokines: TNFα, RANTES, and IP-10. We also show that PFB significantly reduces ROS production by IL-1β-activated astrocytes. Furthermore, PFB also reduces the expression of ICAM and VCAM, both in activated and naïve human astrocytes in vitro. Since reactive astrocytes play an essential role in the neuroinflammatory state preceding neurodegenerative diseases, this study suggests that PFB may have a potential role in their prevention and/or treatment.

A Comparative Proteomics Analysis of Five Body Fluids: Plasma, Urine, Cerebrospinal Fluid, Amniotic Fluid, and Saliva

PURPOSE

Body fluid is considered a rich source of disease biomarkers. Proteins in many body fluids have potential clinical applications for disease diagnostic and prognostic predictions.

EXPERIMENTAL DESIGN

To determine differences in the protein components and functional features of body fluids, a proteomic comparison of five body fluids (plasma, urine, cerebrospinal fluid, saliva, and amniotic fluid) was conducted by high-resolution mass spectrometry.

RESULTS

A total of 4717 nonredundant proteins were identified, and the concentrations of 3433 proteins were estimated by an intensity-based algorithm quantitation method. Among them, 564 proteins were shared among the five body fluids, with common functions in the coagulation/prothrombin system and inflammatory response. A total of 36.7% of the proteins were detected in only one body fluid and were closely related to their adjacent tissues by function. The functional analysis of the remaining 2986 proteins showed that similar functions might be shared among different body fluids, which highlighted intimate connection in the body.

CONCLUSIONS AND CLINICAL RELEVANCE

The quantitative comparative functional analysis indicated that body fluids might reflect the diverse functions of the whole body rather than the characteristics of their adjacent tissues. The above data might indicate the potential application of body fluids for biomarker discovery.

Increased Intrathecal Chemokine Receptor CCR2 Expression in Multiple Sclerosis

Expression of CCR2, CXCR3 and CCR4 on CD4+ T or CD8+ T cells in blood and cerebrospinal fluid (CSF) for multiple sclerosis (MS) was measured by 3-color flow cytometry, and compared to blood from healthy controls and CSF from patients with other inflammatory neurological diseases (INDs). CD4+CXCR3+/CD4+CCR4+ ratio (representing Th1/Th2 balance) was higher in both CSF and blood of MS patients than those of IND patients or healthy controls. Percentage of CCR2-positive T cells was significantly higher in CSF from MS patients. Increased CCR2 expression on T cells in CSF and Th1/Th2 imbalance may reflect the pathological processes involved in MS.

Immunometabolic profiling of patients with multiple sclerosis identifies new biomarkers to predict disease activity during treatment with interferon beta-1a

Reliable immunologic biomarkers able to monitor disease course during multiple sclerosis (MS) are still missing. We aimed at identifying possible immunometabolic biomarkers able to predict the clinical outcome in MS patients during treatment with interferon (IFN)-beta-1a. We measured in 45 relapsing-remitting (RR) MS patients, blood circulating levels of several immunometabolic markers, at enrolment, and correlated their levels to disease activity and progression over time. Higher levels of interleukin (IL)-6, soluble-CD40-ligand (sCD40L) and leptin at baseline associated with a higher relapse rate and a greater risk of experiencing at least one relapse in the following year. Higher values of soluble tumor necrosis factor receptor (sTNF-R) and leptin at baseline were predictive of a higher number of lesions in the following one-year of follow up. In conclusion, our data suggest that an immunometabolic profiling measuring IL-6, sCD40L, leptin and sTNF-R at baseline, could represent a useful tool to predict disease course in RRMS patients during treatment with IFN-beta-1a.

C-X-C motif chemokine 10 in non-alcoholic steatohepatitis: role as a pro-inflammatory factor and clinical implication

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. Non-alcoholic steatohepatitis (NASH) is a more severe form of NAFLD and causes subsequent pathological changes including cirrhosis and hepatocellular carcinoma. Inflammation is the key pathological change in NASH and involves a series of cytokines and chemokines. The C-X-C motif chemokine 10 (CXCL10), which is known as a pro-inflammation chemokine, was recently proven to play a pivotal role in the pathogenesis of NASH. Hepatic CXCL10 is mainly secreted by hepatocytes and liver sinusoidal endothelium. By binding to its specific receptor CXCR3, CXCL10 recruits activated CXCR3+ T lymphocytes and macrophages to parenchyma and promotes inflammation, apoptosis and fibrosis. The circulating CXCL10 level correlates with the severity of lobular inflammation and is an independent risk factor for NASH patients. Thus, CXCL10 may be both a potential prognostic tool and a therapeutic target for the treatment of patients with NASH. The aim of this review is to highlight the growing advances in basic knowledge and clinical interest of CXCL10 in NASH to propagate new insights into novel pharmacotherapeutic avenues.

Cerebrospinal fluid biomarkers of inflammation and degeneration as measures of fingolimod efficacy in multiple sclerosis

BACKGROUND

The disease-modifying therapies (DMTs) in relapsing-remitting multiple sclerosis (RRMS) vary in their mode of action and when therapies are changed, the consequences on inflammatory and degenerative processes are largely unknown.

OBJECTIVE

We investigated the effect of switching from other DMTs to fingolimod on cerebrospinal fluid (CSF) biomarkers.

METHODS

43 RRMS patients were followed up after 4-12 months of fingolimod treatment. Concentrations of C-X-C motif chemokine 13 (CXCL13), chemokine (C-C motif) ligand 2 (CCL2), chitinase-3-like protein 1 (CHI3L1), glial fibrillary acidic protein (GFAP), neurofilament light protein (NFL), and neurogranin (NGRN) were analyzed by enzyme-linked immunosorbent assay (ELISA), while chitotriosidase (CHIT1) was analyzed by spectrofluorometry.

RESULTS

The levels of NFL, CXCL13, and CHI3L1 decreased ( p < 0.05) after fingolimod treatment. Subgroup analysis revealed a reduction in NFL ( p < 0.001), CXCL13 ( p = 0.001), CHI3L1 ( p < 0.001), and CHIT1 ( p = 0.002) in patients previously treated with first-line therapies. In contrast, the levels of all analyzed biomarkers were essentially unchanged in patients switching from natalizumab.

CONCLUSION

We found reduced inflammatory activity (CXCL13, CHI3L1, and CHIT1) and reduced axonal damage (NFL) in patients switching from first-line DMTs to fingolimod. Biomarker levels in patients switching from natalizumab indicate similar effects on inflammatory and degenerative processes. The CSF biomarkers provide an additional measure of treatment efficacy.

An investigation of polymorphisms in the 4q13.3-21.1 CXC chemokine gene cluster for association with multiple sclerosis in Australians

Susceptibility to multiple sclerosis (MS) is believed to result from the complex interaction of a number of genes, each with modest effect. Vital to the migration of cells to sites of inflammation, including the central nervous system, are chemokines, many of which are implicated in MS pathogenesis. Most of the CXC chemokine genes are encoded in a cluster on chromosome 4q13.3-21.1, which has been identified in several genome-wide screens as being potentially associated with MS. We conducted a two-stage analysis to investigate the chemokine gene cluster for association with MS. Initially, we sequenced the chemokine genes in several DNA pools to identify common polymorphisms, and then genotyped selected SNPs in 373 Australian MS trio families. We found no evidence that the CXC chemokine gene cluster is genetically associated with MS. However, the existence of common variants conferring small risk factors or rare variants with significant risk cannot be excluded.

Prenatal fat-rich diet exposure alters responses of embryonic neurons to the chemokine, CCL2, in the hypothalamus

Maternal consumption of a high-fat diet (HFD) during pregnancy is found to stimulate the genesis of hypothalamic orexigenic peptide neurons in the offspring, while HFD intake in adult animals produces a systemic low-grade inflammation which increases neuroimmune factors that may affect neurogenesis and neuronal migration. Building on this evidence and our recent study showing that the inflammatory chemokine, CCL2, stimulates the migration of hypothalamic neurons and expression of orexigenic neuropeptides, we tested here the possibility that prenatal exposure to a HFD in rats affects this chemokine system, both CCL2 and its receptors, CCR2 and CCR4, and alters its actions on hypothalamic neurons, specifically those expressing the neuropeptides, enkephalin (ENK) and galanin (GAL). Using primary dissociated hypothalamic neurons extracted from embryos on embryonic day 19, we found that prenatal HFD exposure compared to chow control actually reduces the expression of CCL2 in these hypothalamic neurons, while increasing CCR2 and CCR4 expression, and also reduces the sensitivity of hypothalamic neurons to CCL2. The HFD abolished the dose-dependent, stimulatory effect of CCL2 on the number of migrated neurons and even shifted its normal stimulatory effect on migrational velocity and distance traveled by control neurons to an inhibition of migration. Further, it abolished the dose-dependent, stimulatory effect of CCL2 on neuronal expression of ENK and GAL. These results demonstrate that prenatal HFD exposure greatly disturbs the functioning of the CCL2 chemokine system in embryonic hypothalamic neurons, reducing its endogenous levels and ability to promote the migration of neurons and their expression of orexigenic peptides.

Theiler's virus infection provokes the overexpression of genes coding for the chemokine Ip10 (CXCL10) in SJL/J murine astrocytes, which can be inhibited by modulators of estrogen receptors

Theiler's murine encephalomyelitis virus (TMEV) induces demyelination in susceptible strains of mice (SJL/J) through an immunopathological process that is mediated by CD4(+) Th1 T cell. These T cells are chemoattracted to the central nervous system by chemokines. Hence, in this study, we focused on the production of the chemokine "interferon-gamma-inducible protein 10 kDa," or IP-10/CXCL10, by cultured SJL/J mouse astrocytes infected with the BeAn strain of TMEV and its capacity to attract activated T cells. The analysis of the whole murine genome by DNA hybridization with cRNAs from mock- and TMEV-infected cultures revealed the upregulation of six sequences that potentially encode for CXCL10. This increased CXCL10 expression was validated by PCR and qPCR. The presence of this chemokine was further demonstrated by enzyme-linked immunoassay (ELISA). Significantly, astrocytes from BALB/c mice, a strain resistant to demyelination, did not produce CXCL10. The secreted CXCL10 was biologically active, inducing chemoattraction of activated lymphocytes. The inflammatory cytokines, IL-1α, IFN-γ, and TNF-α, were strong inducers of CXCL10 in astrocytes. Serum from TMEV-infected SJL/J but not BALB/c mice contains CXCL10, the levels of which peak at the onset of the clinical disease. Finally, this in vitro inflammation model was fully inhibited by 17β-estradiol and four selective estrogen receptor modulators, as demonstrated by ELISA and qPCR.

Cerebrospinal fluid monocyte chemoattractant protein-1 in alcoholics: support for a neuroinflammatory model of chronic alcoholism

BACKGROUND

Liver inflammation in alcoholism has been hypothesized to influence the development of a neuroinflammatory process in the brain characterized by neurodegeneration and altered cognitive function. Monocyte chemoattractant protein-1/chemokine (C-C motif) ligand 2 (MCP-1/CCL2) elevations have been noted in the alcoholic brain at autopsy and may have a role in this process.

METHODS

We studied cerebrospinal fluid (CSF) levels of MCP-1 as well as interleukin-1β and tumor necrosis factor-α in 13 healthy volunteers and 28 alcoholics during weeks 1 and 4 following detoxification. Serum liver enzymes were obtained as markers of alcohol-related liver inflammation.

RESULTS

Compared to healthy volunteers, MCP-1 levels were significantly higher in alcoholics both on day 4 and day 25 (p < 0.0001). Using multiple regression analysis, we found that MCP-1 concentrations were positively associated with the liver enzymes gamma glutamyltransferase (GGT; p = 0.03) and aspartate aminotransferase/glutamic oxaloacetic transaminase (AST/GOT; p = 0.004).

CONCLUSIONS

These preliminary findings are consistent with the hypothesis that neuroinflammation as indexed by CSF MCP-1 is associated with alcohol-induced liver inflammation, as defined by peripheral concentrations of GGT and AST/GOT.

Chemokine network in multiple sclerosis: role in pathogenesis and targeting for future treatments

Multiple sclerosis is the most common inflammatory disorder of the CNS. Evidence suggests that an immunomediated mechanism plays a crucial role during the development of the disease. Currently, two classes of immunomodulatory agents -- interferon-beta and glatiramer acetate (Copaxone, Teva Pharmaceutical Industries), have been approved for the long-term treatment of multiple sclerosis. New drugs which effectively target the immunological processes occurring in multiple sclerosis have been proposed. This review summarizes the immunological background that occurs during the pathogenesis of multiple sclerosis focusing on chemokines and related receptors. The effects of standard treatments on the immune system are analyzed along with the current knowledge of potential new immunomodulatory molecules, such as antiadhesion molecules, statins, estriol, cannabinoids, neurotrophic factors and chemokine antagonists.

The good and the bad of neuroinflammation in multiple sclerosis

Multiple sclerosis (MS) is the most common inflammatory, demyelinating, neurodegenerative disorder of the central nervous system (CNS). It is widely considered a T-cell mediated autoimmune disease that develops in genetically susceptible individuals, possibly under the influence of certain environmental trigger factors. The invasion of autoreactive CD4+ T-cells into the CNS is thought to be a central step that initiates the disease. Several other cell types, including CD8+ T-cells, B-cells and phagocytes appear to be involved in causing inflammation and eventually neurodegeneration. But inflammation is not entirely deleterious in MS. Evidence has accumulated in the recent years that show the importance of regulatory immune mechanisms which restrain tissue damage and initiate regeneration. More insight into the beneficial aspects of neuroinflammation might allow us to develop new treatment strategies for this enigmatic disease.

Biomarkers for multiple sclerosis

Magnetic resonance imaging has been shown to be a powerful tool for diagnosing multiple sclerosis (MS) and evaluating surrogate markers of the disease activity. However, biomarkers may provide more accurate information regarding ongoing immune responses leading to demyelination and treatment effects in MS patients. Although serum biomarkers are easily accessible, they do not provide clear-cut results, whereas cerebrospinal fluid (CSF) biomarkers provide unequivocal information, although samples cannot be repeatedly obtained. For diagnosis, the presence of oligoclonal IgG bands remains important. In addition, measuring the levels of adhesion molecules, matrix metalloproteinase-9 and complement regulator factor H in the serum and evaluating the proportion of Th1/Th2 cells in the blood may be clinically feasible for monitoring the disease activity. In CSF samples, increased IL-8, IL-12, IL-17, CCL3, CCL5 and CXCL10 levels indicate active disease, and the flow cytometry findings of CSF cells can be used to detect increases in Th1 and CD4(+)CD25(+) cells during relapse. Biomarkers closely linked to the disease activity may be informative of the pathogenesis of MS, while those associated with tissue damage or repair may be targets of new treatment strategies. Establishing the latter will be a primary point of research in the near future.

Low DPP4 expression and activity in multiple sclerosis

Multiple sclerosis (MS) is a prototypic Th1/Th17 chronic autoimmune disease of the central nervous system. Dipeptidyl peptidase 4 (DPP4 or CD26) is a multifunctional molecule involved in autoimmune diseases' pathophysiology. We sought to integrate disparate pieces of data and analyze the plasma levels of sDPP4, DPP activity and DPP4 surface expression on T-cells in 129 MS patients with different clinical forms and 53 healthy controls, across two independent cohorts. Herein, we provide new evidence that sDPP4 concentration and DPP activity are significantly lower in MS patients than controls (p < 0.0001 and p < 0.01, respectively). In contrast, the frequency of circulating CD8(+)DPP4(hi) T-cells (p = 0.02) was increased in MS patients. This is the first study that simultaneously analyzes DPP4 expression and function in a large cohort of MS patients. Our data indicate a putative role for DPP4 in MS pathophysiology and suggest that a deeper understanding of surface versus shed DPP4 biology is warranted.

In active relapsing-remitting multiple sclerosis, effector T cell resistance to adaptive T(regs) involves IL-6-mediated signaling

Patients with multiple sclerosis (MS) manifest demyelination and neurodegeneration mediated in part by CD4(+) T cells that have escaped regulation. Resistance of pathogenic effector T cells (T(effs)) to suppression by regulatory T cells (T(regs)) has been demonstrated in several autoimmune diseases. Although impairment in T(reg) number and function has been observed in relapsing-remitting MS (RRMS), T(eff) resistance has not been well studied in this disease. To determine whether T(eff) resistance contributes to failed tolerance in RRMS, we performed T(reg) suppression assays with T(effs) from either RRMS patients not on immunomodulatory therapy or healthy individuals. T(eff) resistance was present in the T(effs) of RRMS patients with active disease but not from patients with inactive disease. Interleukin-6 (IL-6) and phosphorylation of signal transducer and activator of transcription 3 (pSTAT3) promote T(eff) resistance to T(regs), and we found an increase in IL-6 receptor α (IL-6Rα) expression and elevated IL-6 signaling as measured by pSTAT3 in our RRMS subjects. Further, the impaired suppression in RRMS subjects correlated with an increase in IL-6Rα surface expression on CD4(+) T cells and an increase in pSTAT3 in response to IL-6. To address whether the enhanced pSTAT3 contributed to T(eff) resistance in active RRMS patients, we blocked STAT3 phosphorylation and found that impaired suppression was reversed. Therefore, enhanced IL-6R signaling through pSTAT3, in some cases through increased IL-6Rα expression, contributed to T(eff) resistance in active RRMS. These markers may aid in determining disease activity and responsiveness to immunomodulatory therapies in RRMS.

Inflammation markers in multiple sclerosis: CXCL16 reflects and may also predict disease activity

Background

Serum markers of inflammation are candidate biomarkers in multiple sclerosis (MS). ω-3 fatty acids are suggested to have anti-inflammatory properties that might be beneficial in MS. We aimed to explore the relationship between serum levels of inflammation markers and MRI activity in patients with relapsing remitting MS, as well as the effect of ω-3 fatty acids on these markers.

Methods

We performed a prospective cohort study in 85 relapsing remitting MS patients who participated in a randomized clinical trial of ω-3 fatty acids versus placebo (the OFAMS study). During a period of 24 months 12 repeated magnetic resonance imaging (MRI) scans and nine serum samples were obtained. We measured 10 inflammation markers, including general down-stream markers of inflammation, specific markers of up-stream inflammatory pathways, endothelial action, and matrix regulation.

Results

After Bonferroni correction, increasing serum levels of CXCL16 and osteoprotegerin were associated with low odds ratio for simultaneous MRI activity, whereas a positive association was observed for matrix metalloproteinase (MMP) 9. CXCL16 were also associated with low MRI activity the next month, but this was not significant after Bonferroni correction. In agreement with previously reported MRI and clinical results, ω-3 fatty acid treatment did not induce any change in the inflammation markers.

Conclusions

Serum levels of CXCL16, MMP-9, and osteoprotegerin reflect disease activity in MS, but are not affected by ω-3 fatty acid treatment. CXCL16 could be a novel biomarker and potential predictor of disease activity in MS.

Comparative study of the cytokine/chemokine response in children with differing disease severity in enterovirus 71-induced hand, foot, and mouth disease

Background

Enterovirus 71 (EV71) infection can lead to a rapidly progressing, life-threatening, and severe neurological disease in young children, including the development of human hand, foot, and mouth disease (HFMD). This study aims to further characterize the specific immunological features in EV71–mediated HFMD patients presenting with differing degrees of disease severity.

Methodology

Comprehensive cytokine and chemokine expression were broadly evaluated by cytokine antibody array in EV71–infected patients hospitalized for HFMD compared to Coxsackievirus A16-infected patients and age-matched healthy controls. More detailed analysis using Luminex-based cytokine bead array was performed in EV71–infected patients stratified into diverse clinic outcomes. Additionally, immune cell frequencies in peripheral blood and EV71–specific antibodies in plasma were also examined.

Principal Findings

Expression of several cytokines and chemokines were significantly increased in plasma from EV71–infected patients compared to healthy controls, which further indicated that: (1) GM-CSF, MIP-1β, IL-2, IL-33, and IL-23 secretion was elevated in patients who rapidly developed disease and presented with uncomplicated neurological damage; (2) G-CSF and MCP-1 were distinguishably secreted in EV71 infected very severe patients presenting with acute respiratory failure; (3) IP-10, MCP-1, IL-6, IL-8, and G-CSF levels were much higher in cerebrospinal fluid than in plasma from patients with neurological damage; (4) FACS analysis revealed that the frequency of CD19⁺HLADR⁺ mature B cells dynamically changed over time during the course of hospitalization and was accompanied by dramatically increased EV71–specific antibodies. Our data provide a panoramic view of specific immune mediator and cellular immune responses of HFMD and may provide useful immunological profiles for monitoring the progress of EV71–induced fatal neurological symptoms with acute respiratory failure.

Expression of CXCR3 and its ligands CXCL9, -10 and -11 in paediatric opsoclonus-myoclonus syndrome

Opsoclonus-myoclonus syndrome (OMS) is a neuroinflammatory disorder associated with remote cancer. To understand more clearly the role of inflammatory mediators, the concentration of CXCR3 ligands CXCL10, CXCL9 and CXCL11 was measured in 245 children with OMS and 81 paediatric controls using enzyme-linked immunosorbent assay (ELISA), and CXCR3 expression on CD4(+) T cells was measured by flow cytometry. Mean cerebrospinal fluid (CSF) CXCL10 was 2·7-fold higher in untreated OMS than controls. Intrathecal production was demonstrated by significantly different CXCL10 CSF : serum ratios. The dichotomized 'high' CSF CXCL10 group had higher CSF leucocyte count (P = 0·0007) and B cell activating factor (BAFF) and CXCL13 concentrations (P < 0·0001). CSF CXCL10 did not correlate with clinical severity or relapse using grouped data, although it did in some patients. Among seven types of immunotherapy, including rituximab or chemotherapy, only adrenocorticotrophic hormone (ACTH) monotherapy showed reduced CSF CXCL10, but prospective longitudinal studies of ACTH combination therapies indicated no reduction in CXCL10 despite clinical improvement (P < 0·0001). CXCL10 concentrations were 11-fold higher in CSF and twofold higher in serum by multiplexed fluorescent bead-based immunoassay than enzyme-linked immunosorbent assay, but the two correlated (r = 0·7 and 0·83). In serum, no group differences for CXCL9 or CXCL11 were found. CXCR3 expression on CD4(+) T cells was fivefold higher in those from CSF than blood, but was not increased in OMS or altered by conventional immunotherapy. These data suggest alternative roles for CXCL10 in OMS. Over-expression of CXCL10 was not reduced by clinical immunotherapies as a whole, indicating the need for better therapeutic approaches.

High Circulating Chemokines (C-X-C Motif) Ligand 9, and (C-X-C Motif) Ligand 11, in Hepatitis C-Associated Cryoglobulinemia

(C-X-C motif) ligand 9 and (C-X-C motif) ligand 11 (CXCL9 and CXCL11), are potent chemoattractants for activated T cells, and play an important role in T helper 1 (Th) 1 cell recruitment in chronic hepatitis C. No study has evaluated CXCL9, together with CXCL11, circulating levels in patients with mixed cryoglobulinemia and hepatitis C (MC+HCV-p). The aim of the present study therefore was to measure serum CXCL9, and CXCL11 levels, in MC+HCV-p, and to relate the findings to the clinical phenotype. Serum CXCL9 and CXCL11 were measured in 71 MC+HCV-p and in matched controls. MC+HCV-p showed significantly higher mean CXCL9 and CXCL11 levels than controls (P < 0.001, for both), in particular, in 32 patients with active vasculitis (P < 0.001). By defining high CXCL9 or CXCL11 level as a value of at least 2 SD above the mean value of the control group (> 100 pg/mL): 89% MC+HCV-p and 5% controls had high CXCL9 (P < 0.0001, chi-square); 90% MC+HCV-p and 6% controls had high CXCL11 (P < 0.0001, chi-square). In a multiple linear regression model of CXCL9 vs age, ALT, CXCL11, only CXCL11 was significantly (r = 0.452, P < 0.0001) and independently related to CXCL9. Our study demonstrates in MC+HCV-p vs controls: (i) high serum CXCL9, and CXCL11, significantly associated with the presence of active vasculitis; (ii) a strong relationship between circulating CXCL9 and CXCL11. Future studies on a larger cohort of patients are needed to evaluate the relevance of serum CXCL9 and CXCL11 determination as clinico-prognostic marker of MC+HCV.

Programming of neurotoxic cofactor CXCL-10 in HIV-1-associated dementia: abrogation of CXCL-10-induced neuro-glial toxicity in vitro by PKC activator

Background

More than 50% of patients undergoing lifelong suppressive antiviral treatment for HIV-1 infection develop minor HIV-1-associated neurocognitive disorders. Neurological complications during HIV-1 infection are the result of direct neuronal damage by proinflammatory products released from HIV-1-infected or -uninfected activated lymphocytes, monocytes, macrophages, microglia and astrocytes. The specific pro-inflammatory products and their roles in neurotoxicity are far from clear. We investigated proinflammatory cytokines and chemokines in the cerebrospinal fluid (CSF) of HIV-demented (HIV-D) and HIV-nondemented (HIV-ND) patients and studied their affect on neuroglial toxicity.

Methods and results

Bioplex array showed elevated levels of signatory chemokines or cytokines (IL-6, IFN-γ, CXCL10, MCP-1 and PDGF) in the CSF of HIV-D patients (n = 7) but not in that of HIV-ND patients (n = 7). Among the signatory cytokines and chemokines, CXCL10 was distinctly upregulated in-vitro in HIV-1 (NLENG1)-activated human fetal astrocytes, HIV-1 (Ba-L)-infected macrophages, and HIV-1 (NLENG1)-infected lymphocytes. Virus-infected macrophages also had increased levels of TNF-α. Consistently, human fetal astrocytes treated with HIV-1 and TNF-α induced the signatory molecules. CXCL10 in combination with HIV-1 synergistically enhanced neuronal toxicity and showed chemotactic activity (~ 40 fold) for activated peripheral blood mononuclear cells (PBMC), suggesting the intersection of signaling events imparted by HIV-1 and CXCL10 after binding to their respective surface receptors, CXCR4 and CXCR3, on neurons. Blocking CXCR3 and its downstream MAP kinase (MAPK) signaling pathway suppressed combined CXCL10 and HIV-1-induced neurotoxicity. Bryostatin, a PKC modulator and suppressor of CXCR4, conferred neuroprotection against combined insult with HIV-1 and CXCL10. Bryostatin also suppressed HIV-1 and CXCL10-induced PBMC chemotaxis. Although, therapeutic targeting of chemokines in brain may have adverse consequences on the host, current findings and earlier evidence suggest that CXCL10 could strongly impede neuroinflammation.

Conclusion

We have demonstrated induction of CXCL10 and other chemokines/cytokines during HIV-1 infection in the brain, as well as synergism of CXCL10 with HIV-1 in neuronal toxicity, which was dampened by bryostatin.

CCR2(+)CCR5(+) T cells produce matrix metalloproteinase-9 and osteopontin in the pathogenesis of multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease of the CNS that is presumably mediated by CD4(+) autoimmune T cells. Although both Th1 and Th17 cells have the potential to cause inflammatory CNS pathology in rodents, the identity of pathogenic T cells remains unclear in human MS. Given that each Th cell subset preferentially expresses specific chemokine receptors, we were interested to know whether T cells defined by a particular chemokine receptor profile play an active role in the pathogenesis of MS. In this article, we report that CCR2(+)CCR5(+) T cells constitute a unique population selectively enriched in the cerebrospinal fluid of MS patients during relapse but not in patients with other neurologic diseases. After polyclonal stimulation, the CCR2(+)CCR5(+) T cells exhibited a distinct ability to produce matrix metalloproteinase-9 and osteopontin, which are involved in the CNS pathology of MS. Furthermore, after TCR stimulation, the CCR2(+)CCR5(+) T cells showed a higher invasive potential across an in vitro blood-brain barrier model compared with other T cells. Of note, the CCR2(+)CCR5(+) T cells from MS patients in relapse are reactive to myelin basic protein, as assessed by production of IFN-γ. We also demonstrated that the CCR6(-), but not the CCR6(+), population within CCR2(+)CCR5(+) T cells was highly enriched in the cerebrospinal fluid during MS relapse (p < 0.0005) and expressed higher levels of IFN-γ and matrix metalloproteinase-9. Taken together, we propose that autoimmune CCR2(+)CCR5(+)CCR6(-) Th1 cells play a crucial role in the pathogenesis of MS.

Simultaneous evaluation of the circulating levels of both Th1 and Th2 chemokines in patients with autoimmune Addison's disease

BACKGROUND

Chemokines play a key role in the recruitment of the immune cells into the autoimmune process. Thus, the simultaneous evaluation of circulating levels of Th1-related chemokines, such as CX chemokine ligand 10 (CXCL10) and macrophage inflammatory proteins 1α (CCL3/MIP-1α), and Th2-related chemokines, such as macrophage inflammatory proteins 1 β (CCL4/MIP-1β) could be useful in the approach to some autoimmune diseases, including autoimmune Addison's disease (AAD).

AIM

To evaluate plasmatic levels of MIP-1α, MIP-1β, CXCL10 and adrenocortical antibodies in patients with AAD under treatment with corticosteroids.

PATIENTS AND METHODS

Twelve women and 5 men (group 1) were divided in 2 subgroups: 9 subjects with isolated AAD (group 1a) and 8 with AAD associated with chronic autoimmune thyroiditis (group 1b). MIP-1α, MIP- 1β and CXCL10 were evaluated in the serum of all patients and in 20 healthy controls, using a system for microarray suspension.

RESULTS

The levels of MIP-1α, MIP-1β and CXCL10 resulted significantly increased vs controls (p<0.001). An inverse significant correlation between the serum levels of MIP- 1β and the duration of the disease was observed.

CONCLUSION

High levels of MIP-1α and MIP-1β associated with increased levels of CXCL10 in AAD seem to indicate a role of these chemokines in the autoimmune pathology of adrenal gland through the recruitment in loco of Th1 and Th2 cells. The simultaneous measurement of Th1-related chemokines (CXCL10 and MIP-1α) and of Th2-related chemokine MIP-1β in the serum of patients with AAD would sustain a novel preliminary hypothesis on the immune microenvironment of chronic autoimmune inflammation within adrenal glands.

Evaluation of serum levels of chemokines during interferon-β treatment in multiple sclerosis patients: a 1-year, observational cohort study

BACKGROUND

The molecules that provide access to activated T cells in the CNS, including chemokines, have been considered to be a crucial step in the pathogenesis of multiple sclerosis (MS).

AIMS

In this study, we investigated serial serum chemokine levels in patients with relapsing-remitting MS over 1 year and the association of these chemokine levels with treatment regimens, lesions on MRI and patients' characteristics.

METHODS

Serum CXCL9, CXCL10, CCL2, CCL4 and CCL5 levels were evaluated using ELISA every 2 months for a year in 28 healthy controls and 28 MS patients during their treatment with interferon (IFN)-β. Patients underwent MRI and were evaluated using the Expanded Disability Status Scale (EDSS) at the first and final evaluations.

RESULTS

CXCL10 serum levels were higher in MS patients compared with controls, were positively correlated with T2 lesions on MRI and were slightly increased during relapses. Treatment with IFNβ-1a or IFNβ-1b was associated with increased CXCL10 levels when evaluated more than 36 hours after subcutaneous injection. The CXCL9 levels were higher after MS relapse. There was significant variability in CCL4 and CCL5 levels in the serial evaluations, associated with gender and treatment. CCL2 levels were higher in treated MS patients than healthy controls, particularly among those patients with a stable form of the disease.

CONCLUSION

Serum is a feasible resource for searching for an immunological marker in MS. Peripheral chemokine levels correlated in different ways with IFNβ therapy and with disease and patient characteristics.

CLINICAL TRIAL REGISTRATION NUMBER

ISRCTN45526724.

Gene expression studies in multiple sclerosis

Multiple sclerosis (MS) is a serious neurological disorder affecting young Caucasian individuals, usually with an age of onset at 18 to 40 years old. Females account for approximately 60x of MS cases and the manifestation and course of the disease is highly variable from patient to patient. The disorder is characterised by the development of plaques within the central nervous system (CNS). Many gene expression studies have been undertaken to look at the specific patterns of gene transcript levels in MS. Human tissues and experimental mice were used in these gene-profiling studies and a very valuable and interesting set of data has resulted from these various expression studies. In general, genes showing variable expression include mainly immunological and inflammatory genes, stress and antioxidant genes, as well as metabolic and central nervous system markers. Of particular interest are a number of genes localised to susceptible loci previously shown to be in linkage with MS. However due to the clinical complexity of the disease, the heterogeneity of the tissues used in expression studies, as well as the variable DNA chips/membranes used for the gene profiling, it is difficult to interpret the available information. Although this information is essential for the understanding of the pathogenesis of MS, it is difficult to decipher and define the gene pathways involved in the disorder. Experiments in gene expression profiling in MS have been numerous and lists of candidates are now available for analysis. Researchers have investigated gene expression in peripheral mononuclear white blood cells (PBMCs), in MS animal models Experimental Allergic Encephalomyelitis (EAE) and post mortem MS brain tissues. This review will focus on the results of these studies.

Interferon-β but not Glatiramer acetate stimulates CXCL10 secretion in primary cultures of thyrocytes: a clue for understanding the different risks of thyroid dysfunctions in patients with multiple sclerosis treated with either of the two drugs

Autoimmune thyroid disease (AITD) has been reported in patients with multiple sclerosis (MS) receiving interferon-beta (IFN-β), but not in those receiving Glatiramer acetate (GA). CXCL10 is a chemokine playing a pathogenetic role in AITD and MS. Our aim was to evaluate the effects on CXCL10 secretion of IFN-β and GA, alone and in combination with TNF-α, in primary cultures of thyrocytes (PCT). Significant and dose-dependent secretions of CXCL10 were induced by IFN-β but not GA. TNF-α synergistically increased IFN-β induced CXCL10 secretion. These results may provide an explanation for the occurrence of AITD during IFN-β, but not during GA, treatment for MS.

CCL2 and CCR2 variants are associated with skeletal muscle strength and change in strength with resistance training

Baseline muscle size and muscle adaptation to exercise are traits with high variability across individuals. Recent research has implicated several chemokines and their receptors in the pathogenesis of many conditions that are influenced by inflammatory processes, including muscle damage and repair. One specific chemokine, chemokine (C-C motif) ligand 2 (CCL2), is expressed by macrophages and muscle satellite cells, increases expression dramatically following muscle damage, and increases expression further with repeated bouts of exercise, suggesting that CCL2 plays a key role in muscle adaptation. The present study hypothesizes that genetic variations in CCL2 and its receptor (CCR2) may help explain muscle trait variability. College-aged subjects [n = 874, Functional Single-Nucleotide Polymorphisms Associated With Muscle Size and Strength (FAMUSS) cohort] underwent a 12-wk supervised strength-training program for the upper arm muscles. Muscle size (via MR imaging) and elbow flexion strength (1 repetition maximum and isometric) measurements were taken before and after training. The study participants were then genotyped for 11 genetic variants in CCL2 and five variants in CCR2. Variants in the CCL2 and CCR2 genes show strong associations with several pretraining muscle strength traits, indicating that inflammatory genes in skeletal muscle contribute to the polygenic system that determines muscle phenotypes. These associations extend across both sexes, and several of these genetic variants have been shown to influence gene regulation.

Cytokine and chemokine profiles in neuromyelitis optica: significance of interleukin-6

BACKGROUND

Neuromyelitis optica (NMO) is assumed to be immunologically distinct from multiple sclerosis (MS). Adequate studies about cytokines and chemokines in NMO have been lacking.

OBJECTIVE

To investigate the contribution of cytokines/chemokines in the pathogenesis of NMO.

METHODS

We measured 27 cytokines/chemokines and Th17 cell-associated cytokines in the cerebrospinal fluid (CSF) of 31 NMO, 29 MS and 18 other non-inflammatory neurological disorders patients. The serum levels of some cytokines/ chemokines were also measured. The correlations between clinical characteristics/laboratory findings and levels of cytokines/chemokines in NMO were examined.

RESULTS

The CSF levels of interleukin (IL)-1 receptor antagonist, IL-6, IL-8, IL-13 and granulocyte colony-stimulating factor were significantly increased in NMO, while IL-9, fibroblast growth factor-basic, granulocyte macrophage colony-stimulating factor, macrophage inflammatory protein-1-beta and tumor necrosis factor-alpha were increased in MS. IL-10 and interferon-gamma-inducible protein-10 were elevated in NMO and MS. In serum analyses, only the IL-6 level showed significant elevation in NMO. The CSF IL-6 level had a significant correlation with the CSF glial fibrillary acidic protein level and CSF cells, and a weak correlation with anti-aquaporin-4 antibody titers.

CONCLUSIONS

Different immunological status and pathophysiologies exist between NMO and MS, and IL-6 may play important roles in the pathogenesis of NMO.

Role of chemokines in CNS health and pathology: a focus on the CCL2/CCR2 and CXCL8/CXCR2 networks

Chemokines and their receptors have crucial roles in the trafficking of leukocytes, and are of particular interest in the context of the unique immune responses elicited in the central nervous system (CNS). The chemokine system CC ligand 2 (CCL2) with its receptor CC receptor 2 (CCR2), as well as the receptor CXCR2 and its multiple ligands CXCL1, CXCL2 and CXCL8, have been implicated in a wide range of neuropathologies, including trauma, ischemic injury and multiple sclerosis. This review aims to overview the current understanding of chemokines as mediators of leukocyte migration into the CNS under neuroinflammatory conditions. We will specifically focus on the involvement of two chemokine networks, namely CCL2/CCR2 and CXCL8/CXCR2, in promoting macrophage and neutrophil infiltration, respectively, into the lesioned parenchyma after focal traumatic brain injury. The constitutive brain expression of these chemokines and their receptors, including their recently identified roles in the modulation of neuroprotection, neurogenesis, and neurotransmission, will be discussed. In conclusion, the value of evidence obtained from the use of Ccl2- and Cxcr2-deficient mice will be reported, in the context of potential therapeutics inhibiting chemokine activity which are currently in clinical trial for various inflammatory diseases.