Modulation of experimental autoimmune encephalomyelitis: effect of altered peptide ligand on chemokine and chemokine receptor expression

Enhanced and complementary benefits of a nalfurafine and fingolimod combination to treat immune-driven demyelination

OBJECTIVES

Multiple sclerosis (MS) is a neurodegenerative disease characterised by inflammation and damage to myelin sheaths. While all current disease-modifying treatments (DMTs) are very effective at reducing relapses, they do not slow the progression of the disease, and there is little evidence that these treatments are able to repair or remyelinate damaged axons. Recent evidence suggests that activating kappa opioid receptors (KORs) has a beneficial effect on the progression of MS, and this study investigates the effects of KOR agonists treatment in combination with two current DMTs.

METHODS

Using the well-established murine model for immune-driven demyelination of MS, experimental autoimmune encephalomyelitis, the effect of KOR agonists in combination with DMTs fingolimod or dimethyl fumarate on disease progression, immune cell infiltration and activation as well as myelination were analysed.

RESULTS

Fingolimod in combination with the KOR agonist, nalfurafine, significantly increased each individual beneficial effect as measured by increased recovery of mice and reduced relapses. These beneficial effects correlated with a reduction in immune cell infiltration into the CNS as well as peripheral immune cell alterations including a reduction in autoreactive CD4+ T-cell cytokine production as well as increased myelination in the spinal cords of co-treated animals. In contrast, while the use of dimethyl fumarate in combination with nalfurafine did not adversely affect the benefits of nalfurafine, the combination did not significantly enhance those benefits.

CONCLUSION

This study indicates that KOR agonists can be used in combination with fingolimod and dimethyl fumarate with the nalfurafine-fingolimod combination providing enhanced benefits.

Histamine H4 Receptor Agonist, 4-Methylhistamine, Aggravates Disease Progression and Promotes Pro-Inflammatory Signaling in B Cells in an Experimental Autoimmune Encephalomyelitis Mouse Model

We sought to assess the impact of 4-Methylhistamine (4-MeH), a specific agonist targeting the Histamine H4 Receptor (H4R), on the progression of experimental autoimmune encephalomyelitis (EAE) and gain insight into the underlying mechanism. EAE is a chronic autoimmune, inflammatory, and neurodegenerative disease of the central nervous system (CNS) characterized by demyelination, axonal damage, and neurodegeneration. Over the past decade, pharmacological research into the H4R has gained significance in immune and inflammatory disorders. For this study, Swiss Jim Lambert EAE mice were treated with 4-MeH (30 mg/kg/day) via intraperitoneal administration from days 14 to 42, and the control group was treated with a vehicle. Subsequently, we evaluated the clinical scores. In addition, flow cytometry was employed to estimate the impact of 4-Methylhistamine (4-MeH) on NF-κB p65, GM-CSF, MCP-1, IL-6, and TNF-α within CD19+ and CXCR5+ spleen B cells. Additionally, we investigated the effect of 4-MeH on the mRNA expression levels of Nf-κB p65, Gmcsf, Mcp1, Il6, and Tnfα in the brain of mice using RT-PCR. Notably, the clinical scores of EAE mice treated with 4-MeH showed a significant increase compared with those treated with the vehicle. The percentage of cells expressing CD19+NF-κB p65+, CXCR5+NF-κB p65+, CD19+GM-CSF+, CXCR5+GM-CSF+, CD19+MCP-1+, CXCR5+MCP-1+, CD19+IL-6+, CXCR5+IL-6+, CD19+TNF-α+, and CXCR5+TNF-α+ exhibited was more pronounced in 4-MeH-treated EAE mice when compared to vehicle-treated EAE mice. Moreover, the administration of 4-MeH led to increased expression of NfκB p65, Gmcsf, Mcp1, Il6, and Tnfα mRNA in the brains of EAE mice. This means that the H4R agonist promotes pro-inflammatory mediators aggravating EAE symptoms. Our results indicate the harmful role of H4R agonists in the pathogenesis of MS in an EAE mouse model.

DAPTA, a C-C Chemokine Receptor 5 (CCR5), Leads to the Downregulation of Notch/NF-κB Signaling and Proinflammatory Mediators in CD40+ Cells in Experimental Autoimmune Encephalomyelitis Model in SJL/J Mice

Multiple sclerosis (MS) is an autoimmune inflammatory disease of the central nervous system characterized by motor deficits, cognitive impairment, fatigue, pain, and sensory and visual dysfunction. CD40, highly expressed in B cells, plays a significant role in MS pathogenesis. The experimental autoimmune encephalomyelitis (EAE) mouse model of MS has been well established, as well as its relevance in MS patients. This study aimed to evaluate the therapeutic potential of DAPTA, a selective C-C chemokine receptor 5 (CCR5) antagonist in the murine model of MS, and to expand the knowledge of its mechanism of action. Following the induction of EAE, DAPTA was administrated (0.01 mg/kg, i.p.) daily from day 14 to day 42. We investigated the effects of DAPTA on NF-κB p65, IκBα, Notch-1, Notch-3, GM-CSF, MCP-1, iNOS, and TNF-α in CD40⁺ spleen B cells using flow cytometry. Furthermore, we also analyzed the effect of DAPTA on NF-κB p65, IκBα, Notch-1, Notch-3, GM-CSF, MCP-1, iNOS, and TNF-α mRNA expression levels using qRT-PCR in brain tissue. EAE mice treated with DAPTA showed substantial reductions in NF-κB p65, Notch-1, Notch-3, GM-CSF, MCP-1, iNOS, and TNF-α but an increase in the IκBα of CD40⁺ B lymphocytes. Moreover, EAE mice treated with DAPTA displayed decreased NF-κB p65, Notch-1, Notch-3, GM-CSF, MCP-1, iNOS, and TNF-α and but showed increased IκBα mRNA expression levels. This study showed that DAPTA has significant neuroprotective potential in EAE via the downregulation of inflammatory mediators and NF-κB/Notch signaling. Collectively, DAPTA might have potential therapeutic targets for use in MS treatment.

Grape Seed Extract Attenuates Demyelination in Experimental Autoimmune Encephalomyelitis Mice by Inhibiting Inflammatory Response of Immune Cells

OBJECTIVE

To examine the anti-inflammatory effect of grape seed extract (GSE) in animal and cellular models and explore its mechanism of action.

METHODS

This study determined the inhibitory effect of GSE on macrophage inflammation and Th1 and Th17 polarization in vitro. Based on the in vitro results, the effects and mechanisms of GSE on multiple sclerosis (MS)-experimental autoimmune encephalomyelitis (EAE) mice model were further explored. The C57BL/6 mice were intragastrically administered with 50 mg/kg of GSE once a day from the 3rd day to the 27th day after immunization. The activation of microglia, the polarization of Th1 and Th17 and the inflammatory factors such as tumor necrosis factor- α (TNF- α), interleukin-1 β (IL-1 β), IL-6, IL-12, IL-17 and interferon-γ (IFN-γ) secreted by them were detected in vitro and in vivo by flow cytometry, enzyme linked immunosorbent assay (ELISA), immunofluorescence staining and Western blot, respectively.

RESULTS

GSE reduced the secretion of TNF-α, IL-1 β and IL-6 in bone marrow-derived macrophages stimulated by lipopolysaccharide (P<0.01), inhibited the secretion of TNF-α, IL-1 β, IL-6, IL-12, IL-17 and IFN-γ in spleen cells of EAE mice immunized for 9 days (P<0.05 or P<0.01), and reduced the differentiation of Th1 and Th17 mediated by CD3 and CD28 factors (P<0.01). GSE significantly improved the clinical symptoms of EAE mice, and inhibited spinal cord demyelination and inflammatory cell infiltration. Peripherally, GSE downregulated the expression of toll-like-receptor 4 (TLR4) and Rho-associated kinase (ROCKII, P<0.05 or P<0.01), and inhibited the secretion of inflammatory factors (P<0.01 or P<0.05). In the central nervous system, GSE inhibited the infiltration of CD45⁺CD11b⁺ and CD45⁺CD4⁺ cells, and weakened the differentiation of Th1 and Th17 (P<0.05). Moreover, it reduced the secretion of inflammatory factors (P<0.01), and prevented the activation of microglia (P<0.05).

CONCLUSION

GSE had a beneficial effect on the pathogenesis and progression of EAE by inhibiting inflammatory response as a potential drug and strategy for the treatment of MS.

Clozapine reduces chemokine-mediated migration of lymphocytes by targeting NF-κB and AKT phosphorylation

Multiple sclerosis is a disease characterised by demyelination of axons in the central nervous system. The atypical antipsychotic drug clozapine has been shown to attenuate disease severity in experimental autoimmune encephalomyelitis (EAE), a mouse model that is useful for the study of multiple sclerosis. However, the mechanism of action by which clozapine reduces disease in EAE is poorly understood. To better understand how clozapine exerts its protective effects, we investigated the underlying signalling pathways by which clozapine may reduce immune cell migration by evaluating chemokine and dopamine receptor-associated signalling pathways. We found that clozapine inhibits migration of immune cells by reducing chemokine production in microglia cells by targeting NF-κB phosphorylation and promoting an anti-inflammatory milieu. Furthermore, clozapine directly targets immune cell migration by changing Ca²⁺ levels within immune cells and reduces the phosphorylation of signalling protein AKT. Linking these pathways to the antagonising effect of clozapine on dopamine and serotonin receptors, we provide insight into how clozapine alters immune cells migration by directly targeting the underlying migration-associated pathways.

Murine endometrial-derived mesenchymal stem cells suppress experimental autoimmune encephalomyelitis depending on indoleamine-2,3-dioxygenase expression

Cellular therapy with mesenchymal stem cells (MSCs) is a huge challenge for scientists, as little translational relevance has been achieved. However, many studies using MSCs have proved their suppressive and regenerative capacity. Thus, there is still a need for a better understanding of MSCs biology and the establishment of newer protocols, or to test unexplored tissue sources. Here, we demonstrate that murine endometrial-derived MSCs (meMSCs) suppress Experimental Autoimmune Encephalomyelitis (EAE). MSC-treated animals had milder disease, with a significant reduction in Th1 and Th17 lymphocytes in the lymph nodes and in the central nervous system (CNS). This was associated with increased Il27 and Cyp1a1 expression, and presence of IL-10-secreting T CD4+ cells. At EAE peak, animals had reduced CNS infiltrating cells, histopathology and demyelination. qPCR analysis evidenced the down-regulation of several pro-inflammatory genes and up-regulation of indoleamine-2,3-dioxygenase (IDO). Consistently, co-culturing of WT and IDO-/- meMSCs with T CD4+ cells evidenced the necessity of IDO on the suppression of encephalitogenic lymphocytes, and IDO-/- meMSCs were not able to suppress EAE. In addition, WT meMSCs stimulated with IL-17A and IFN-γ increased IDO expression and secretion of kynurenines in vitro, indicating a negative feedback loop. Pathogenic cytokines were increased when CD4+ T cells from AhR-/- mice were co-cultured with WT meMSC. In summary, our research evidences the suppressive activity of the unexplored meMSCs population, and shows the mechanism depends on IDO-kynurenines-Aryl hydrocarbon receptor (AhR) axis. To our knowledge this is the first report evidencing that the therapeutic potential of meMSCs relying on IDO expression.

Oleacein Attenuates the Pathogenesis of Experimental Autoimmune Encephalomyelitis through Both Antioxidant and Anti-Inflammatory Effects

Oxidative stress and proinflammatory cytokines are factors affecting multiple sclerosis (MS) disease progression. Oleacein (OLE), an olive secoiridoid, possesses powerful antioxidant and anti-inflammatory activities, which suggests its potential application to treat neuroinflammatory disorders. Herein, we investigated the impact of OLE on the main clinic-pathological features of experimental autoimmune encephalomyelitis (EAE), an animal model for MS, including paralysis, demyelination, central nervous system (CNS) inflammation/oxidative stress and blood-brain barrier (BBB) breakdown.

METHODS

Mice were immunized with the myelin oligodendrocyte glycoprotein peptide, MOG_35-55, to induce EAE, and OLE was administrated from immunization day. Serum, optic nerve, spinal cord and cerebellum were collected to evaluate immunomodulatory activities at a systemic level, as well as within the CNS. Additionally, BV2 microglia and the retinal ganglion cell line RGC-5 were used to confirm the direct effect of OLE on CNS-resident cells.

RESULTS

We show that OLE treatment effectively reduced clinical score and histological signs typical of EAE. Histological evaluation confirmed a decrease in leukocyte infiltration, demyelination, BBB disruption and superoxide anion accumulation in CNS tissues of OLE-treated EAE mice compared to untreated ones. OLE significantly decreased expression of proinflammatory cytokines (IL-13, TNFα, GM-CSF, MCP-1 and IL-1β), while it increased the anti-inflammatory cytokine IL-10. Serum levels of anti-MOG_35-55 antibodies were also lower in OLE-treated EAE mice. Further, OLE significantly diminished the presence of oxidative system parameters, while upregulated the ROS disruptor, Sestrin-3. Mechanistically, OLE prevented NLRP3 expression, phosphorylation of p65-NF-κB and reduced the synthesis of proinflammatory mediators induced by relevant inflammatory stimuli in BV2 cells. OLE did not affect viability or the phagocytic capabilities of BV2 microglia. In addition, apoptosis of RGC-5 induced by oxidative stressors was also prevented by OLE.

CONCLUSION

Altogether, our results show that the antioxidant and anti-inflammatory OLE has neuroprotective effects in the CNS of EAE mice, pointing out this natural product as a candidate to consider for research on MS treatments.

Clozapine reduces infiltration into the CNS by targeting migration in experimental autoimmune encephalomyelitis

Background

Atypical antipsychotic agents, such as clozapine, are used to treat schizophrenia and other psychiatric disorders by a mechanism that is believed to involve modulating the immune system. Multiple sclerosis is an immune-mediated neurological disease, and recently, clozapine was shown to reduce disease severity in an animal model of MS, experimental autoimmune encephalomyelitis (EAE). However, the mode of action by which clozapine reduces disease in this model is poorly understood.

Methods

Because the mode of action by which clozapine reduces neuroinflammation is poorly understood, we used the EAE model to elucidate the in vivo and in vitro effects of clozapine.

Results

In this study, we report that clozapine treatment reduced the infiltration of peripheral immune cells into the central nervous system (CNS) and that this correlated with reduced expression of the chemokines CCL2 and CCL5 transcripts in the brain and spinal cord. We assessed to what extent immune cell populations were affected by clozapine treatment and we found that clozapine targets the expression of chemokines by macrophages and primary microglia. Furthermore, in addition to decreasing CNS infiltration by reducing chemokine expression, we found that clozapine directly inhibits chemokine-induced migration of immune cells. This direct target on the immune cells was not mediated by a change in receptor expression on the immune cell surface but by decreasing downstream signaling via these receptors leading to a reduced migration.

Conclusions

Taken together, our study indicates that clozapine protects against EAE by two different mechanisms; first, by reducing the chemoattractant proteins in the CNS; and second, by direct targeting the migration potential of peripheral immune cells.

Loss of TIPE2 Has Opposing Effects on the Pathogenesis of Autoimmune Diseases

Autoimmune diseases are a physiological state wherein immune responses are directed against and damage the body's own tissues. Cytokines secreted by infiltrated inflammatory cells contribute to the pathogenesis of autoimmune diseases. TIPE2, one of the four family members of Tumor necrosis factor-α induced protein-8 (TNFAIP8), is a negative regulator of innate and adaptive immunity and plays essential roles in the maintenance of immune tolerance. However, studies on the role of TIPE2 during the development of autoimmune diseases have generated contradictory results. In the current study, we sought to determine the role of TIPE2 during the development of IMQ-induced psoriasis and Experimental Autoimmune Uveitis (EAU) in mice. Our study revealed that, while TIPE2-deficiency alleviates psoriasis, it exacerbates the development of EAU. Further studies demonstrated that, although TIPE2-deficient T cells produced more IL-17A, they do not migrate efficiently to the local inflammatory site, i.e., the skin. This in turn led to the decreased IL-17A production in the skin and consequently reduced the severity of psoriasis in TIPE2-deficient mice. However, although TIPE2-deficient T cells still produced more IL-17A in EAU model, they migrate into the inflamed eye as efficient as TIPE2-sufficient T cells, and consequently exacerbates the development of EAU in TIPE2-deficient mice. Taken together, these results indicate that TIPE2 may either promote or suppress autoimmunity depending on the specific inflammatory microenvironment in different types of autoimmune diseases.

The C-C Chemokines CCL17 and CCL22 and Their Receptor CCR4 in CNS Autoimmunity

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). It affects more than two million people worldwide, mainly young adults, and may lead to progressive neurological disability. Chemokines and their receptors have been shown to play critical roles in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a murine disease model induced by active immunization with myelin proteins or transfer of encephalitogenic CD4⁺ T cells that recapitulates clinical and neuropathological features of MS. Chemokine ligand-receptor interactions orchestrate leukocyte trafficking and influence multiple pathophysiological cellular processes, including antigen presentation and cytokine production by dendritic cells (DCs). The C-C class chemokines 17 (CCL17) and 22 (CCL22) and their C-C chemokine receptor 4 (CCR4) have been shown to play an important role in homeostasis and inflammatory responses. Here, we provide an overview of the involvement of CCR4 and its ligands in CNS autoimmunity. We review key clinical studies of MS together with experimental studies in animals that have demonstrated functional roles of CCR4, CCL17, and CCL22 in EAE pathogenesis. Finally, we discuss the therapeutic potential of newly developed CCR4 antagonists and a humanized anti-CCR4 antibody for treatment of MS.

Effects of active immunisation with myelin basic protein and myelin-derived altered peptide ligand on pain hypersensitivity and neuroinflammation

Neuropathic pain is a debilitating condition in multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). Specific myelin basic protein (MBP) peptides are encephalitogenic, and myelin-derived altered peptide ligands (APLs) are capable of preventing and ameliorating EAE. We investigated the effects of active immunisation with a weakly encephalitogenic epitope of MBP (MBP87-99) and its mutant APL (Cyclo-87-99[A(91),A(96)]MBP87-99) on pain hypersensitivity and neuroinflammation in Lewis rats. MBP-treated rats exhibited significant mechanical and thermal pain hypersensitivity associated with infiltration of T cells, MHC class II expression and microglia activation in the spinal cord, without developing clinical signs of paralysis. Co-immunisation with APL significantly decreased pain hypersensitivity and neuroinflammation emphasising the important role of neuroimmune crosstalk in neuropathic pain.

Animal models of systemic sclerosis: their utility and limitations

Without doubt, animal models have provided significant insights into our understanding of the rheumatological diseases; however, no model has accurately replicated all aspects of any autoimmune disease. Recent years have seen a plethora of knockouts and transgenics that have contributed to our knowledge of the initiating events of systemic sclerosis, an autoimmune disease. In this review, the focus is on models of systemic sclerosis and how they have progressed our understanding of fibrosis and vasculopathy, and whether they are relevant to the pathogenesis of systemic sclerosis.

'Neuroinflammation' differs categorically from inflammation: transcriptomes of Alzheimer's disease, Parkinson's disease, schizophrenia and inflammatory diseases compared

'Neuroinflammation' has become a widely applied term in the basic and clinical neurosciences but there is no generally accepted neuropathological tissue correlate. Inflammation, which is characterized by the presence of perivascular infiltrates of cells of the adaptive immune system, is indeed seen in the central nervous system (CNS) under certain conditions. Authors who refer to microglial activation as neuroinflammation confuse this issue because autoimmune neuroinflammation serves as a synonym for multiple sclerosis, the prototypical inflammatory disease of the CNS. We have asked the question whether a data-driven, unbiased in silico approach may help to clarify the nomenclatorial confusion. Specifically, we have examined whether unsupervised analysis of microarray data obtained from human cerebral cortex of Alzheimer's, Parkinson's and schizophrenia patients would reveal a degree of relatedness between these diseases and recognized inflammatory conditions including multiple sclerosis. Our results using two different data analysis methods provide strong evidence against this hypothesis demonstrating that very different sets of genes are involved. Consequently, the designations inflammation and neuroinflammation are not interchangeable. They represent different categories not only at the histophenotypic but also at the transcriptomic level. Therefore, non-autoimmune neuroinflammation remains a term in need of definition.

Effects of vaccination with altered Peptide ligand on chronic pain in experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis

Neuropathic pain is a chronic symptom of multiple sclerosis (MS) and affects nearly half of all MS sufferers. A key instigator of this pain is the pro-inflammatory response in MS. We investigated the behavioral effects of immunization with a mutant peptide of myelin basic protein (MBP), termed altered peptide ligand (APL), known to initiate immune deviation from a pro-inflammatory state to an anti-inflammatory response in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. Male and female Lewis rats were injected with vehicle control or with varying doses of 50 or 100 μg guinea pig MBP in combination with or without APL. APL-treated animals established significantly lower disease severity compared to encephalitogenic MBP-treated animals. Animals with EAE developed mechanical, but not thermal pain hypersensitivity. Mechanical pain sensitivities were either improved or normalized during periods of clinical disease in male and female APL-treated animals as compared to the encephalitogenic group. No significant changes to thermal latency were observed upon co-immunization with APL. Together these data indicate that APL ameliorates disease states and selectively mediates an analgesic effect on EAE animals.

Pain in experimental autoimmune encephalitis: a comparative study between different mouse models

BACKGROUND

Pain can be one of the most severe symptoms associated with multiple sclerosis (MS) and develops with varying levels and time courses. MS-related pain is difficult to treat, since very little is known about the mechanisms underlying its development. Animal models of experimental autoimmune encephalomyelitis (EAE) mimic many aspects of MS and are well-suited to study underlying pathophysiological mechanisms. Yet, to date very little is known about the sensory abnormalities in different EAE models. We therefore aimed to thoroughly characterize pain behavior of the hindpaw in SJL and C57BL/6 mice immunized with PLP139-151 peptide or MOG35-55 peptide respectively. Moreover, we studied the activity of pain-related molecules and plasticity-related genes in the spinal cord and investigated functional changes in the peripheral nerves using electrophysiology.

METHODS

We analyzed thermal and mechanical sensitivity of the hindpaw in both EAE models during the whole disease course. Qualitative and quantitative immunohistochemical analysis of pain-related molecules and plasticity-related genes was performed on spinal cord sections at different timepoints during the disease course. Moreover, we investigated functional changes in the peripheral nerves using electrophysiology.

RESULTS

Mice in both EAE models developed thermal hyperalgesia during the chronic phase of the disease. However, whereas SJL mice developed marked mechanical allodynia over the chronic phase of the disease, C57BL/6 mice developed only minor mechanical allodynia over the onset and peak phase of the disease. Interestingly, the magnitude of glial changes in the spinal cord was stronger in SJL mice than in C57BL/6 mice and their time course matched the temporal profile of mechanical hypersensitivity.

CONCLUSIONS

Diverse EAE models bearing genetic, clinical and histopathological heterogeneity, show different profiles of sensory and pathological changes and thereby enable studying the mechanistic basis and the diversity of changes in pain perception that are associated with distinct types of MS.

Strain-dependent variation in the early transcriptional response to CNS injury using a cortical explant system

Background

While it is clear that inbred strains of mice have variations in immunological responsiveness, the influence of genetic background following tissue damage in the central nervous system is not fully understood. A cortical explant system was employed as a model for injury to determine whether the immediate transcriptional response to tissue resection revealed differences among three mouse strains.

Methods

Immunological mRNAs were measured in cerebral cortex from SJL/J, C57BL/6J, and BALB/cJ mice using real time RT-PCR. Freshly isolated cortical tissue and cortical sections incubated in explant medium were examined. Levels of mRNA, normalized to β-actin, were compared using one way analysis of variance with pooled samples from each mouse strain.

Results

In freshly isolated cerebral cortex, transcript levels of many pro-inflammatory mediators were not significantly different among the strains or too low for comparison. Constitutive, baseline amounts of CD74 and antisecretory factor (ASF) mRNAs, however, were higher in SJL/J and C57BL/6J, respectively. When sections of cortical tissue were incubated in explant medium, increased message for a number of pro-inflammatory cytokines and chemokines occurred within five hours. Message for chemokines, IL-1α, and COX-2 transcripts were higher in C57BL/6J cortical explants relative to SJL/J and BALB/cJ. IL-1β, IL-12/23 p40, and TNF-α were lower in BALB/cJ explants relative to SJL/J and C57BL/6J. Similar to observations in freshly isolated cortex, CD74 mRNA remained higher in SJL/J explants. The ASF mRNA in SJL/J explants, however, was now lower than levels in both C57BL/6J and BALB/cJ explants.

Conclusions

The short-term cortical explant model employed in this study provides a basic approach to evaluate an early transcriptional response to neurological damage, and can identify expression differences in genes that are influenced by genetic background.

Management of acute exacerbations in multiple sclerosis

A key component of multiple sclerosis is the occurrence of episodes of clinical worsening with either new symptoms or an increase in older symptoms over a few days or weeks. These are known as exacerbations of multiple sclerosis. In this review, we summarize the pathophysiology and treatment of exacerbations and describe how they are related to the overall management of this disease.

Novel therapeutic strategies targeting the pathogenic T-cells in multiple sclerosis

Multiple sclerosis is a chronic disease in which immune cells incite inflammation in the central nervous system, ultimately resulting in the destruction of the myelin nerve sheath. Pathogenic CD4+ T-cells are believed to be responsible for initiating this process. Recent advances in molecular biology, such as transgenic and knockout animal models, genomics and proteomics, have allowed for a much greater understanding of the cellular and subcellular pathways involved in autoimmunity. The end result is an ever more specific array of potential therapeutic agents, each designed to target one component of the dysregulated immune system and in some cases, specific to each individual patient. The mechanisms, promises and pitfalls of these various strategies for the treatment of multiple sclerosis are the topic of this review.

The chemokine receptor antagonist, TAK-779, decreased experimental autoimmune encephalomyelitis by reducing inflammatory cell migration into the central nervous system, without affecting T cell function

BACKGROUND AND PURPOSE

The C-C chemokine receptor CCR5, and the C-X-C chemokine receptor CXCR3 are involved in the regulation of T cell-mediated immune responses, and in the migration and activation of these cells. To determine whether blockade of these chemokine receptors modulated inflammatory responses in the central nervous sytem (CNS), we investigated the effect of a non-peptide chemokine receptor antagonist, TAK-779, in mice with experimental autoimmune encephalomyelitis (EAE).

EXPERIMENTAL APPROACH

EAE was induced by immunization of C57BL/6 mice with myelin oligodendrocyte glycoprotein (MOG) 35-55. TAK-779 was injected s.c. once a day after immunization. Disease incidence and severity (over 3 weeks) were monitored by histopathological evaluation and FACS assay of inflammatory cells infiltrating into the spinal cord, polymerase chain reaction quantification of mRNA expression, assay of T cell proliferation, by [3H]-thymidine incorporation and cytokine production by enzyme-linked immunosorbent assay.

KEY RESULTS

Treatment with TAK-779 reduced incidence and severity of EAE. It strongly inhibited migration of CXCR3/CCR5 bearing CD4+, CD8+ and CD11b+ leukocytes to the CNS. TAK-779 did not reduce proliferation of anti-MOG T cells, the production of IFN-gamma by T cells or CXCR3 expression on T cells. In addition, TAK-779 did not affect production of IL-12 by antigen-presenting cells, CCR5 induction on T cells and the potential of MOG-specific T cells to transfer EAE.

CONCLUSIONS AND IMPLICATIONS

TAK-779 restricted the development of MOG-induced EAE. This effect involved reduced migration of inflammatory cells into the CNS without affecting responses of anti-MOG T cells or the ability of MOG-specific T cells to transfer EAE.

HIV Coreceptors and Their Roles in Leukocyte Trafficking During Neuroinflammatory Diseases

Due to the increasing resistance of HIV-1 to antiretroviral therapies, there has been much emphasis on the discovery and development of alternative therapeutics for HIV-1-infected individuals. The chemokine receptors CXCR4 (Bleul et al. 1996a; Feng et al. 1996; Nagasawa et al. 1996; Oberlin et al. 1996) and CCR5 (Alkhatib et al. 1996; Deng et al. 1996; Dragic et al. 1996) were identified as target molecules from the time their role as coreceptors for HIV-1 entry into leukocytes was first discovered 10 years ago. Initial studies focused on the use of the chemokine ligands, or altered derivatives, of CXCR4 and CCR5 to prevent the entrance of HIV-1 into immune cells (Schols 2006). While these studies showed some initial promise, there was evidence of significant caveats to their use, including selection of alternative coreceptor utilizing strains (Marechal et al. 1999; Mosier et al. 1999) and the potential to cause inflammatory side effects. These data prompted the development and study of small molecule inhibitors of CXCR4 and CCR5, which have also been used to examine the roles of these molecules in a variety of inflammatory and infectious diseases.

An antibody to IP-10 is a potent antagonist of cell migration in vitro and in vivo and does not affect disease in several animal models of inflammation

IP-10 secretion is induced by pro-inflammatory cytokines and mediates the migration of CXCR3+ cells. Its elevation in clinical samples has been associated with multiple inflammatory diseases and its antagonism has been reported to be effective in several animal models of inflammatory disease. We generated a mouse anti-mouse IP-10 monoclonal antibody (mAb; Clone 20A9) that specifically bound murine IP-10 with high affinity and inhibited in vitro IP-10 induced BaF3/mCXCR3 cell migration with an IC(50) of approximately 4 nM. The 20A9 mAb was completely absorbed in vivo and had dose proportional pharmacokinetic exposure with a serum half life of 2.4-6 days. The 20A9 mAb inhibited IP-10 mediated T-cell recruitment to the airways, indicating that it is effective in vivo. However, administration of the 20A9 mAb had no significant effect on disease in mouse models of delayed type hypersensitivity, collagen induced arthritis, cardiac allograft transplantation tolerance, EAE or CD4+ CD45RBHi T-cell transfer-induced IBD. These data suggest that the 20A9 mAb can antagonize IP-10 mediated chemotaxis in vitro and in vivo and that this is insufficient to cause a therapeutic benefit in multiple mouse models of inflammatory disease.

Administration of a monomeric CCL2 variant to EAE mice inhibits inflammatory cell recruitment and protects from demyelination and axonal loss

Based on gene expression data, we tested the P8A-CCL2 variant of the chemokine CCL2, able to interfere with the chemotactic properties of the parental molecule, in relapsing-remitting (RR)-EAE SJL. Only preventive treatment significantly delayed disease onset in a dose dependent manner. P8A-CCL2 administration, however, decreased demyelination, axonal loss and number of CNS infiltrating T cells and macrophages. Immunological analysis revealed that P8A-CCL2 does not act on Ag-specific T cell proliferation and does not interfere with the differentiation of IFNgamma-releasing effectors T cells. These results suggest that the therapeutic mechanism of P8A-CCL2 may rely on interference with immune cell recruitment.

Modulation of biodistribution and expression of plasmid DNA following mesenchymal progenitor cell-based delivery

Although therapeutic applications of mesenchymal progenitor cells (MPCs) have been studied, the in vivo fate of genes delivered by the MPCs has received little attention. We report here the in vivo kinetics, tissue distribution, and duration of gene expression after systemic administration of plasmid DNA delivered by MPCs. Murine MPCs were isolated from bone marrow, cultured, and transfected with plasmid DNA using polyethylenimine. The gene-modified MPCs or naked plasmid DNA was administered intravenously to mice. Injected MPCs incorporating plasmid DNA yielded elevated serum concentrations when compared with the group treated with plasmid DNA alone, a 280-fold higher level measured at 5-min post-administration. Moreover, plasmid DNA delivered in MPCs was detected in several organs, lymph nodes, and bone marrow. The highest levels of distribution were observed in the liver, followed by lung and spleen at 4 days post-dose. Similar to the distribution of DNA, significant expression levels of the exogenous gene were observed only after delivery of the DNA in MPCs, demonstrating the sustained expression at the liver, lung, and kidney for 4 days after tail vein injection. This study provides perspectives regarding the in vivo fate and target tissue distribution of genes following MPC-based delivery.

Antagonism of the chemokine receptors CXCR3 and CXCR4 reduces the pathology of experimental autoimmune encephalomyelitis

Chemokines regulate lymphocyte trafficking under physiologic and pathologic conditions. In this study, we have investigated the role of CXCR3 and CXCR4 in the activation of T lymphocytes and their migration to the central nervous system (CNS) using novel mutant chemokines to antagonize CXCR3 and CXCR4 specifically. A series of truncation mutants of CXCL11, which has the highest affinity for CXCR3, were synthesized, and an antagonist, CXCL11((4-79)), was obtained. CXCL11((4-79)) strongly inhibited the migration of activated mouse T cells in response to all three high-affinity CXCR3 ligands, CXCL9, 10 and 11. CXCL12((P2G2)), while exhibiting minimal agonistic activity, potently inhibited the migration of activated mouse T cells in response to CXCL12. Interfering with the action of CXCR3 and CXCR4 with these synthetic receptor antagonists inhibited experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis and reduced the accumulation of CD4(+) T cells in the CNS. Further investigation demonstrated that CXCL12((P2G2)) inhibited the sensitization phase, whereas CXCL11((4-79)) inhibited the effector phase of the immune response. Our data suggest that simultaneous targeting of CXCR4 and CXCR3 may be of benefit in the treatment of the CNS autoimmune disease.

The Th17-ELR+ CXC chemokine pathway is essential for the development of central nervous system autoimmune disease

The ELR⁺ CXC chemokines CXCL1 and CXCL2 are up-regulated in the central nervous system (CNS) during multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). However, their functional significance and the pathways regulating their expression are largely unknown. We show that transfer of encephalitogenic CD4⁺ Th17 cells is sufficient to induce CXCL1 and CXCL2 transcription in the spinal cords of naive, syngeneic recipients. Blockade or genetic silencing of CXCR2, a major receptor for these chemokines in mice, abrogates blood–brain barrier (BBB) breakdown, CNS infiltration by leukocytes, and the development of clinical deficits during the presentation as well as relapses of EAE. Depletion of circulating polymorphonuclear leukocytes (PMN) had a similar therapeutic effect. Furthermore, injection of CXCR2⁺ PMN into CXCR2^−/− mice was sufficient to restore susceptibility to EAE. Our findings reveal that a Th17–ELR⁺ CXC chemokine pathway is critical for granulocyte mobilization, BBB compromise, and the clinical manifestation of autoimmune demyelination in myelin peptide–sensitized mice, and suggest new therapeutic targets for diseases such as MS.

L.E.A.P.S. heteroconjugate is able to prevent and treat experimental autoimmune myocarditis by altering trafficking of autoaggressive cells to the heart

We evaluated the efficacy of the Ligand Epitope Antigen Presentation System (L.E.A.P.S.trade mark) in preventing or treating experimental autoimmune myocarditis (EAM) in A/J mice. L.E.A.P.S. (here, J-My-1) is a conjugate of the myocarditogenic peptide of cardiac myosin MyHCalpha(334-352) (My-1) and J peptide, derived from the sequence of human beta-2 microglobulin. Remarkably, early prophylactic (J-My-1 injected on days -14 and -7 before EAM induction), late prophylactic (J-My-1 injected on days 0, 7, 14, and 21), and therapeutic (J-My-1 injected on days 7, 14, and 21 or 10, 17 and 24) administration of J-My-1 significantly decreased the incidence and severity of EAM. However, extended therapeutic treatment was associated with anaphylaxis and death, corresponding with global immune activation associated with J-My-1 treatment. In J-My1-treated animals, we observed expanded numbers of activated CD69+ and CD44+ CD4+ and CD8+ T cells in the spleens. J-My-1 treatment also increased the proportion of CD11c+ dendritic cells in spleens and induced strong production of anti-J-My-1 specific antibodies. J-My-1 injections resulted in decreased levels of chemokines MIP-1alpha and IP-10 in hearts. We propose that J-My-1 treatment interferes with trafficking of autoaggressive immune cells to the heart.

Astrocytes--friends or foes in multiple sclerosis?

In multiple sclerosis (MS), the presence of demyelinating plaques has concentrated researchers' minds on the role of the oligodendrocyte in its pathophysiology. Recently, with the rediscovery of early and widespread loss of axons in the disease, new emphasis has been put on the role of axons and axon-oligodendrocyte interactions in MS. Despite the fact that, in 1904, Müller claimed that MS was a disease of astrocytes, more recently, astrocytes have taken a back seat, except as the cells that form the final glial scar after all hope of demyelination is over. However, perhaps it is time for the return of the astrocyte to popularity in the pathogenesis of MS, with recent reports on the dual role of astrocytes in aiding degeneration and demyelination, by promoting inflammation, damage of oligodendrocytes and axons, and glial scarring, but also in creating a permissive environment for remyelination by their action on oligodendrocyte precursor migration, oligodendrocyte proliferation, and differentiation. We review these findings to try to provide a cogent view of astrocytes in the pathology of MS.

Expression of chemokine receptors CCR7 and CCR8 in the CNS during ChREAE

Chemokines and their receptors are important players in organism homeostasis, development and immune response to inflammatory stimuli. It has been recently confirmed that they are also involved in the development of several autoimmune diseases. In this study, we analysed the expression of two recently identified CC chemokine receptors, CCR7 and CCR8, in the central nervous system (CNS) and in peripheral tissues during chronic relapsing experimental autoimmune encephalomyelitis (ChREAE) -- an animal model of the human demyelinating disease multiple sclerosis (MS). We observed upregulation of both chemokine receptors in the CNS during the first and second attacks of ChREAE, whereas disease remission was characterized by a lower expression of those receptors. An analysis of the kinetics of CCR7 and CCR8 expression in the CNS during the first attack of the disease showed a constant increase in the first few days after the onset of clinical signs. This expression correlated with the clinical severity of ChREAE. CCR7-positive mononuclear cells were detected mostly in perivascular inflammatory cuffs in the CNS. In peripheral tissues (the spleen and kidneys) expression of both receptors was not upregulated during active ChREAE. These findings suggest that CCR7 and CCR8 may play a significant role in the pathogenesis of EAE and probably MS.

Biodistribution and tissue expression kinetics of plasmid DNA complexed with polyethylenimines of different molecular weight and structure

Polyethylenimine (PEI) has been studied as an efficient and versatile in vitro and in vivo gene delivery agent. Here, we report the in vivo fate, tissue expression duration, and safety after the intravenous injection of plasmid DNA complexed to various PEIs under different conditions. Murine interleukin-2 plasmid DNA was complexed with branched PEI2Kd, 25Kd, or linear PEI25Kd at different N/P ratios. The mean residence time of plasmid DNA was found to be prolonged after delivery in PEI, evidencing the highest values in branched PEI25Kd. As compared to branched PEI25Kd, linear PEI25Kd at the same N/P ratio provided mRNA expression levels orders of magnitude higher in the lung over an 8-day period. In the branched PEI2Kd/DNA complexes, the N/P ratio of 80:1 evidenced higher gene expression efficiency in the kidney and spleen than the normal N/P ratio of 10:1. The generation of proinflammatory chemokine receptors was induced by branched PEI25Kd, but not by other PEIs. The complexes of DNA with linear 25Kd PEI or branched PEI2Kd exhibited no histological changes after repeated administrations. These results indicate that the structure, molecular weight, and N/P ratios of PEIs must be collectively considered and modulated for organ-targeted plasmid DNA delivery.

CCR7, CCR8, CCR9 and CCR10 in the mouse hippocampal CA1 area and the dentate gyrus during and after pilocarpine-induced status epilepticus

The present study showed CCR7, CCR8, CCR9 and CCR10 in the normal Swiss mouse hippocampus at both protein and mRNA levels. CCR7, CCR9 and CCR10 were mainly localized in hippocampal principal cells and some interneurons. CCR9 was also found in the mossy fibres and/or terminals, suggesting an axonal or presynaptic localization, and CCR10 in apical dendrites of pyramidal neurons in the CA1 area. CCR8 was observed in interneurons. Double-labelling immunocytochemistry revealed that most of calbindin (CB)-, calretinin (CR)- and parvalbumin (PV)-immunopositive neurons expressed CCR7-10, except CR-immunopositive cells in which only 10 to 12% expressed CCR8. During and after pilocarpine-induced status epilepticus, progressive changes of each of CCR7, CCR8, CCR9 and CCR10 proteins occurred in different patterns at various time points. Sensitive real-time PCR showed similar change patterns at mRNA level. At the chronic stage, i.e. at 2 months after pilocarpine-induced status epilepticus, significant reduction of CCR7-10 expression in CB-, CR- and PV-immunpositive interneurons may suggest the phenotype change of surviving interneurons. Double labelling of CCR7, CCR8 and CCR9 with glial fibrillary acidic protein (GFAP) at the chronic stage may suggest an induced expression in reactive astrocytes. The present study may, therefore, for the first time, provide evidence that CCR7-10 may be involved in normal hippocampal activity. The demonstration of the progressive changes of CCR7-10 during and after status epilepticus may open a new area to reveal the mechanism of neuronal loss after status epilepticus and of epileptogenesis.

In vivo administration of plasmid DNA encoding recombinant immunotoxin DT390-IP-10 attenuates experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a T-cell-mediated autoimmune demyelinating disease. The expression of chemokine receptor CXCR3 on activated T cells is crucial to direct the migration of effector cells into the inflammatory sites and initiate EAE. In this study we tested the effect of a novel recombinant immunotoxin targeting CXCR3(+) cells for EAE prevention. The immunotoxin construct DT390-IP-10-SRalpha consisted of interferon gamma-inducible protein 10 (IP-10), a ligand of CXCR3, as the targeting moiety, and a truncated diphtheria toxin (DT390) as the toxic moiety. In vitro transfection of DT390-IP-10-SRalpha into NIH3T3 cells resulted in expression of DT390-IP-10 which proved highly toxic to activated T cells. To evaluate the effect of DT390-IP-10-SRalpha on EAE prevention in vivo, cationic liposome-embedded DT390-IP-10-SRalpha was injected into the muscle of hind limbs of C57BL/6 mice immunized by myelin basic protein (MBP). DT390-IP-10-SRalpha-treated mice showed a delayed onset of EAE and milder symptoms compared to the mice treated with empty control plasmid or PBS alone. Immunohistochemical staining detected significantly reduced infiltrating CXCR3(+) cells in the inflammatory lesions of CNS from immunotoxin treated mice as compared to the controls. This study suggests that targeting CXCR3(+) T cells with recombinant immunotoxin could be achieved in vivo to delay and ameliorate murine EAE.

Neutrophil recruitment in immunized mice depends on MIP-2 inducing the sequential release of MIP-1alpha, TNF-alpha and LTB(4)

Neutrophils are thought to play an important role in the tissue damage observed in various autoimmune diseases. Chemokines, cytokines and leukotrienes have recognized roles in the orchestration of neutrophil migration. We have recently shown that antigen-induced neutrophil migration into the peritoneum of immunized mice is mediated by macrophage-inflammatory protein (MIP)-1alpha which interacts with CCR1 and induces the sequential release of TNF-alpha and leukotriene B(4) (LTB(4)). The present study investigates the role of MIP-2 and CXCR2 in the cascade of events leading to mediator generation and neutrophil influx. Antigen challenge of immunized mice induced the expression of CXCR2 and the production of KC and MIP-2 proteins. Antigen-induced neutrophil migration was inhibited by a CXCR2 receptor antagonist (repertaxin) or an anti-MIP-2 antibody, but not by an anti-KC antibody. Administration of MIP-2 promoted a dose-dependent neutrophil migration in naive mice which was inhibited by repertaxin, anti-TNF-alpha, anti-MIP-1alpha antibodies or by MK886 (leukotriene synthesis inhibitor). MIP-2 administration induced the release of MIP-1alpha, TNF-alpha and LTB(4), and the release of the latter two was inhibited by anti-MIP-1alpha antibody treatment. Our studies highlight the intricate balance between mediator production and action during an immune-mediated inflammatory response and suggest a mediator cascade leading to neutrophil influx following antigen challenge of immunized mice: MIP-2 --> MIP-1alpha --> TNF-alpha --> LTB(4).

Translating the concept of suppressor/regulatory T cells to clinical applications

The in vivo expansion of suppressor/regulatory T cells (Tregs) is a desirable event in autoimmunity and transplantation. Here we summarize the general rules involved in antigen recognition by T cells and describe Tregs and their requirements, discussing different levels of immune intervention.

Future of multiple sclerosis therapy: combining antigen-specific immunotherapy with strategies to promote myelin repair

Persistent CNS inflammation and the failure of myelin repair during multiple sclerosis (MS) trigger a progressive deterioration in neurophysiological function and permanent clinical debilitation. Current treatment consists of immunosuppressive therapies targeted against the immune response, which have only been moderately successful in ameliorating disease relapses and have little or no benefit in slowing disease progression or enhancing remyelination. Recent breakthroughs have revealed new targets and more selective techniques for inhibiting autoreactive T-cell responses and promoting lesion repair in animal models of MS. In light of these new findings and the limitations of current treatments, the authors hypothesize that the future of MS therapy will progress towards the development of a combinatorial therapeutic strategy that consists of specific tolerance of autoreactive T cells, myelin repair and axonal protection.

Prevention of murine experimental autoimmune encephalomyelitis by in vivo expression of a novel recombinant immunotoxin DT390-RANTES

Experimental autoimmune encephalomyelitis (EAE) is a T-cell-mediated autoimmune disease. Chemokine receptor CCR5 has been shown to be essential for the T-cell recruitment to the inflammatory site in EAE. In this study, we assumed that an immunotoxin directed at CCR5+ cells would be able to reduce the disease activity of EAE. A recombinant immunotoxin, DT390-RANTES-SRalpha, was constructed in an eukaryotic cell expression plasmid consisting of regulated on activation normal T cells expressed and secreted (RANTES) as the targeting moiety and DT390 as the toxic moiety. DT390-RANTES was expressed in vitro and was highly toxic to activated mouse T cells with the inhibitory concentration 50 at 0.18 ng/ml. To evaluate whether DT390-RANTES was effective in preventing EAE, C57BL/6 mice were immunized with myelin basic protein, emulsified with complete Freund's adjuvant and were treated by injecting cationic liposome-embedded plasmid DNA into the muscle of hind limbs. Mice treated with DT390-RANTES-SRalpha developed a much milder EAE compared to mice treated with phosphate-buffered saline or the empty plasmid DNA. Much less CCR5+-infiltrating cells were found in the central nervous system in DT390-RANTES-SRalpha-treated mice than in the control mice. This study indicates that recombinant immunotoxin can be expressed in vivo, and targeting CCR5 can attenuate the disease activity of EAE in mice.

Differential regulation of the CXCR2 chemokine network in rat brain trauma: Implications for neuroimmune interactions and neuronal survival

Chemokine receptors represent promising targets to attenuate inflammatory responses and subsequent secondary damage after brain injury. We studied the response of the chemokines CXCL1/CINC-1 and CXCL2/MIP-2 and their receptors CXCR1 and CXCR2 after controlled cortical impact injury in adult rats. Rapid upregulation of CXCL1/CINC-1 and CXCL2/MIP-2, followed by CXCR2 (but not CXCR1), was observed after injury. Constitutive neuronal CXCR2 immunoreactivity was detected in several brain areas, which rapidly but transiently downregulated upon trauma. A second CXCR2-positive compartment, mainly colocalized with the activated microglia/macrophage marker ED1, was detected rapidly after injury in the ipsilateral cortex, progressively emerging into deeper areas of the brain later in time. It is proposed that CXCR2 has a dual role after brain injury: (i) homologous neuronal CXCR2 downregulation would render neurons more vulnerable to injury, whereas (ii) chemotaxis and subsequent differentiation of blood-borne cells into a microglial-like phenotype would be promoted by the same receptor.

CXCL10 is the key ligand for CXCR3 on CD8+ effector T cells involved in immune surveillance of the lymphocytic choriomeningitis virus-infected central nervous system

IFN-gamma-inducible protein 10/CXCL10 is a chemokine associated with type 1 T cell responses, regulating the migration of activated T cells through binding to the CXCR3 receptor. Expression of both CXCL10 and CXCR3 are observed during immunopathological diseases of the CNS, and this receptor/ligand pair is thought to play a central role in regulating T cell-mediated inflammation in this organ site. In this report, we investigated the role of CXCL10 in regulating CD8(+) T cell-mediated inflammation in the virus-infected brain. This was done through analysis of CXCL10-deficient mice infected intracerebrally with lymphocytic choriomeningitis virus, which in normal immunocompetent mice induces a fatal CD8(+) T cell-mediated meningoencephalitis. We found that a normal antiviral CD8(+) T cell response was generated in CXCL10-deficient mice, and that lack of CXCL10 had no influence on the accumulation of mononuclear cells in the cerebrospinal fluid. However, analysis of the susceptibility of CXCL10-deficient mice to lymphocytic choriomeningitis virus-induced meningitis revealed that these mice just like CXCR3-deficient mice were partially resistant to this disease, whereas wild-type mice invariably died. Furthermore, despite marked up-regulation of the two remaining CXCR3 ligands: CXCL9 and 11, we found a reduced accumulation of CD8(+) T cells in the brain parenchyma around the time point when wild-type mice succumb as a result of CD8(+) T cell-mediated inflammation. Thus, taken together these results indicate a central role for CXCL10 in regulating the accumulation of effector T cells at sites of CNS inflammation, with no apparent compensatory effect of other CXCR3 ligands.

Neutrophils regulate the expression of cytokines, chemokines and nitric oxide synthase/nitric oxide in mice injected with Bothrops atrox venom

Bothrops atrox crude venom injected intraperitoneal (i.p.) into BALB/c mice induced local afflux of inflammatory cells, one neutrophil-rich peak after 6h and another macrophage-rich peak after 48 h. A similar pattern of local cell afflux plus edema, Delta lesions of some skeletal muscle cells, and hemorrhage were observed in mice intramuscular (i.m.) injected with the venom. Measurement of serum cytokines in neutrophil-depleted (by anti-mouse rat monoclonal antibody (mAb) RB6-8C5) and non-depleted BALB/c mice was performed by ELISA. With the exception of IL-1beta (78 pg/ml), higher levels of IL-6 (1348 pg/ml), MIP-1beta (437 pg/ml) and MIP-2 (904 pg/ml) were observed in neutrophil-depleted mice, in comparison to the values found in non-neutrophil depleted mice: IL-1beta (437 pg/ml), IL-6 (750 pg/ml), MIP-1beta (165 pg/ml) and MIP-2 (90 pg/ml). TNF-alpha was not detected. NO was detected (18 microM) 24h after venom injection in neutrophil-depleted mice. RT-PCR using representative primers detected expression of mRNA in cells from BALB/c mice injected with B. atrox venom: (a) for IL-1beta, IL-6, inducible nitric oxide synthase (iNOS), CXCR2, MIP-2 and RANTES in cells from mice that were neutrophil-depleted or not; (b) for CCR1, CCR5 and MIP-1beta in cells from neutrophil-depleted mice; (c) for MIP-1alpha in cells from non-neutrophil-depleted mice; (d) TNF-alpha and TGF-beta were not detected in either of the mice. These results indicate that neutrophils play a role in regulating the production of some cytokines and chemokines as well as locally expressed or liberated iNOS/NO in tissues injected with B. atrox crude venom.

The expression and function of chemokines involved in CNS inflammation

Chemokines and their receptors have principal roles in leukocyte trafficking under normal physiological and pathological conditions. The differential expression of the chemokine system in different parts of the CNS provides insights into the processes that are required for normal immune surveillance and pathological immune-mediated effector processes. Insights derived from studying multiple sclerosis, an inflammatory disorder of the CNS in humans, and experimental autoimmune encephalomyelitis, an animal model of this disorder, aid in further understanding the complexities of chemokine-mediated inflammation. Knowledge of the molecular biology of chemokines and their receptors, and the roles of specific chemokine ligands and receptors in the CNS in health and in disease have made these proteins targets for therapeutic intervention in neuroinflammation. We also discuss currently proposed and potentially useful chemokine receptor antagonists.

Permanent Survival of Fully MHC-Mismatched Islet Allografts by Targeting a Single Chemokine Receptor Pathway

Chemokine receptor blockade can diminish the recruitment of host effector cells and prolong allograft survival, but little is known of the role of chemokine receptors in promoting host sensitization. We engrafted fully allogeneic islets into streptozotocin-treated normal mice or mice with the autosomal recessive paucity of lymph node T cell (plt) mutation; the latter lack secondary lymphoid expression of the CCR7 ligands, secondary lymphoid organ chemokine (CCL21) and EBV-induced molecule-1 ligand chemokine (CCL19). plt mice showed permanent survival of islets engrafted under the kidney capsule, whereas controls rejected islet allografts in 12 days (p < 0.001), and consistent with this, plt mice had normal allogeneic T cell responses, but deficient migration of donor dendritic cell to draining lymph nodes. Peritransplant i.v. injection of donor splenocytes caused plt recipients to reject their allografts by 12 days, and sensitization at 60 days posttransplant of plt mice with well-functioning allografts restored acute rejection. Finally, islet allografts transplanted intrahepatically in plt mice were rejected approximately 12 days posttransplant, like controls, as were primarily revascularized cardiac allografts. These data show that the chemokine-directed homing of donor dendritic cell to secondary lymphoid tissues is essential for host sensitization and allograft rejection. Interruption of such homing can prevent T cell priming and islet allograft rejection despite normal T and B cell functions of the recipient, with potential clinical implications.

Encephalitogenic and tolerogenic potential of altered peptide ligands of MOG and PLP in Biozzi ABH mice

Altered peptide ligands (APL) are highly effective in inhibiting experimental autoimmune encephalomyelitis (EAE) in rodents although clinical trials in multiple sclerosis reveal severe limitations probably due to the diverse and differential effects of APL in vivo compared to in vitro. Myelin oligodendrocyte glycoprotein (MOG 8-21) induces relapsing EAE in ABH (A(g7)) mice associated with broadening of the autoimmune repertoire thus providing a dynamic system to examine the efficacy of peptide analogues. Subtle changes in MOG 8-21 dramatically influenced disease susceptibility and T cell responses in vitro. Non-encephalitogenic APL that induce production of the 'regulatory' cytokines IL-10 and/or TGFbeta and concomitant low levels of the 'proinflammatory' cytokines IFNgamma and TNFalpha modulated relapsing EAE but were far less effective than the 'proinflammatory' wild-type MOG 8-21 peptide. These data reveal that APL differ greatly in their ability to activate encephalitogenic T cells. The extensive heterogeneity of responses of APL in vitro suggests that selection of APL on this criteria is highly unpredictable and probably less effective for therapy than selecting the dominant wild-type epitope and delivering it using a tolerogenic route.

CCR1 antagonists in clinical development

Chemokines (chemotactic cytokines) are a family of low-molecular-weight proteins that direct the cellular migration of leukocytes by binding to and activating the G protein-coupled receptors displayed on the leukocyte cell surface. The inadvertent or excessive generation of chemokines has been associated with the inflammatory component of several disease processes, and consequently, considerable efforts have been made to characterise chemokine/chemokine receptor interactions with the ultimate aim of therapeutic intervention. This review focuses on the biology of CC chemokine receptor 1, which together with its ligands is thought to recruit leukocytes during the progression of rheumatoid arthritis, multiple sclerosis and organ transplant rejection. The developments made in antagonising this receptor and efficacies of these compounds in the clinical setting are also highlighted.

G protein-coupled receptor kinase 2 in multiple sclerosis and experimental autoimmune encephalomyelitis

Many modulators of inflammation, including chemokines, neuropeptides, and neurotransmitters signal via G protein-coupled receptors (GPCR). GPCR kinases (GRK) can phosphorylate agonist-activated GPCR thereby promoting receptor desensitization. Here we describe that in leukocytes from patients with active relapsing-remitting multiple sclerosis (MS) or with secondary progressive MS, GRK2 levels are significantly reduced. Unexpectedly, cells from patients during remission express even lower levels of GRK2. The level of GRK2 in leukocytes of patients after stroke, a neurological disorder with paralysis but without an autoimmune component, was similar to GRK2 levels in cells from healthy individuals. In addition, we demonstrate that the course of recombinant myelin oligodendrocyte glycoprotein (1-125)-induced experimental autoimmune encephalomyelitis (EAE), an animal model for MS, is markedly different in GRK2(+/-) mice that express 50% of the GRK2 protein in comparison with wild-type mice. Onset of EAE was significantly advanced by 5 days in GRK2(+/-) mice. The earlier onset of EAE was associated with increased early infiltration of the CNS by T cells and macrophages. Although disease scores in the first phase of EAE were similar in both groups, GRK2(+/-) animals did not develop relapses, whereas wild-type animals did. The absence of relapses in GRK2(+/-) mice was associated with a marked reduction in inflammatory infiltrates in the CNS. Recombinant myelin oligodendrocyte glycoprotein-induced T cell proliferation and cytokine production were normal in GRK2(+/-) animals. We conclude that down-regulation of GRK2 expression may have important consequences for the onset and progression of MS.