Intrathecal activation of the IL-17/IL-8 axis in opticospinal multiple sclerosis

The role of CD4 T cells in the pathogenesis of multiple sclerosis

T lymphocytes play a central role in the pathogenesis of multiple sclerosis (MS) (Zhang et al., 1992). Both CD4+ and CD8+ T cells have been demonstrated in MS lesions, with CD4+ T cells predominating in acute lesions and CD8+ T cells being observed more frequently in chronic lesions (Raine, 1994). Additionally, T cells are found in all four of the described histopathologic subtypes of MS (Lucchinetti et al., 2000). Activated myelin-reactive CD4+ T cells are present in the blood and cerebrospinal fluid (CSF) of MS patients; in contrast, only nonactivated myelin-reactive T cells are present in the blood of controls (Zhang et al., 1994). The success of several T-cell-targeted therapies in MS reinforces the importance of the role of the T cell in MS pathogenesis. Here, we outline basic concepts in CD4+ T-cell immunology and summarize the current understanding of the role of CD4+ T cells in the pathogenesis of MS.

Vasoactive intestinal peptide regulates Th17 function in autoimmune inflammation

An imbalance of pro-inflammatory and anti-inflammatory cytokines, autoreactive and inflammatory T helper 1 (Th1) cells, and regulatory T (Treg) cells results in the loss of immune tolerance and the subsequent appearance of inflammatory autoimmune diseases. On the other hand, hormones and neuropeptides are endogenous factors controlling the immune homeostasis that have been proposed as therapeutic agents in different autoimmune disorders. Among them, the vasoactive intestinal peptide (VIP) has been shown to downregulate the inflammatory response and to alter the Th1/Th2 balance in favor of anti-inflammatory Th2 immune responses. Recent studies have revealed a greater diversification of the T cell effector repertoire with the identification of Th17 cells. This subpopulation has been shown to be pathogenic in several autoimmune diseases previously attributed to the Th1 lineage. Arising new data and a critical revision of already published studies indicate that VIP is an immunomodulatory therapeutic agent targeting the Th17/Treg pathway.

The selective Rho-kinase inhibitor Fasudil is protective and therapeutic in experimental autoimmune encephalomyelitis

We studied the role of fasudil, a selective Rho-kinase inhibitor, in experimental autoimmune encephalomyelitis (EAE). Both parenteral and oral administration of fasudil prevented the development of EAE induced by proteolipid protein (PLP) p139-151 in SJL/J mice. Specific proliferation of lymphocytes to PLP was significantly reduced, together with a downregulation of interleukin (IL)-17 and a marked decrease of the IFN-gamma/IL-4 ratio. Immunohistochemical examination also disclosed a marked decrease of inflammatory cell infiltration, and attenuated demyelination and acute axonal transaction. These results may provide a rationale of selective blockade of Rho-kinase by oral use of fasudil as a new therapy for multiple sclerosis.

Intrathecal upregulation of granulocyte colony stimulating factor and its neuroprotective actions on motor neurons in amyotrophic lateral sclerosis

To investigate cytokine/chemokine changes in amyotrophic lateral sclerosis (ALS), we simultaneously measured 16 cytokine/chemokines (interleukin [IL]-1beta, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12 [p70], IL-13, IL-17, interferon-gamma, tumor necrosis factor-alpha, granulocyte colony stimulating factor [G-CSF], macrophage chemoattractant protein-1 [MCP-1], and macrophage inflammatory protein-1beta) in cerebrospinal fluid (CSF) and sera from 37 patients with sporadic ALS and 33 controls using a multiplexed fluorescent bead-based immunoassay. We also conducted immunohistochemical analyses from 8 autopsied ALS cases and 6 nonneurologic disease controls as well as cell culture analyses of relevant cytokines and their receptors. We found that concentrations of G-CSF and MCP-1 were significantly increased in ALS CSF compared with controls. In spinal cords, G-CSF was expressed in reactive astrocytes in ALS cases but not controls, whereas G-CSF receptor expression was significantly decreased in motor neurons of spinal cords from ALS cases. Biologically, G-CSF had a protective effect on the NSC34 cell line under conditions of both oxidative and nutritional stress. We suggested that G-CSF has potentially neuroprotective effects on motor neurons in ALS and that downregulation of its receptor might contribute to ALS pathogenesis. On the other hand, MCP-1 correlated with disease severity, which may aggravate motor neuron damage.

Immunomodulatory effects of 3-hydroxy-3-methylglutaryl coenzyme-A reductase inhibitors, potential therapy for relapsing remitting multiple sclerosis

This study characterized immunomodulatory targets of statins in humans and their potential for treatment of relapsing remitting multiple sclerosis (RR MS). Statins inhibited the proliferative response of mononuclear cells. Simvastatin, the statin with the strongest antiproliferative effect, inhibited IFN-gamma-induced expression of MHC class II DR on monocytes and decreased their antigen presenting capacity. As for T lymphocytes, it inhibited their activation and expression of the Th1 lineage differentiation markers. Simvastatin inhibited IFN-gamma, TNF-alpha, and IL-2 secretion, as well as the expression of T-bet, a transcription factor that regulates Th1 cell differentiation.

Upregulation of myeloperoxidase in patients with opticospinal multiple sclerosis: Positive correlation with disease severity

To clarify the role of myeloperoxidase (MPO) in multiple sclerosis (MS), we measured serum MPO levels in 86 Japanese patients with relapsing remitting MS, 47 with opticospinal MS (OSMS) and 39 with conventional MS (CMS), and 85 healthy subjects by sandwich enzyme immunoassays and analyzed relationships with clinical features. We found a significant increase in serum MPO in OSMS patients at relapse and remission, and in CMS patients at remission compared with controls. By logistic regression analysis, the clinical variable associated with high level of MPO at remission in OSMS patients (higher than the mean+/-2 S.D. of healthy controls) was only Kurtzke's Expanded Disability Status Scale (EDSS) score in blood sampling (p=0.0245); that is, a greater EDSS scores in the high MPO group, whereas in CMS none were associated. The results of our study suggest that MPO levels in remission are related with severe tissue destruction in OSMS.

IL-8 (-251 A/T) and CXCR2 (+1208 C/T) gene polymorphisms and risk of multiple sclerosis in Iranian patients

IL-8 plays important roles in CNS development, modulation of neuronal survival and excitability. Among IL-8 receptors, only CXCR2 is known to be present in the brain. The ability of individuals in producing IL-8 is partially determined by IL-8 -251 A/T polymorphism. Therefore, the aim of the present study was to investigate the association between IL-8 -251 A/T and CXCR2 +1208 C/T gene polymorphisms and susceptibility to multiple sclerosis (MS). Two hundred and twenty-three MS patients and 319 healthy and ethnic matched controls were included in this study. IL-8 promoter (-251 A/T) and CXCR2 (+1208 C/T) gene polymorphisms were genotyped via allele specific PCR (AS-PCR) method. A significant difference was found in IL-8 -251 A/T polymorphism between MS patients and controls (p = 0.04). This deference was a result of a higher incidence of the low producer allele of IL-8 (T allele) in MS patients compared to controls. However, there was no significant association between different clinical findings (EDSS score, progression index, disease onset age, and the type of disease) and IL-8 -251 A/T polymorphism. Furthermore, no significant association existed between CXCR2 +1208 C/T polymorphism and MS susceptibility or different clinical parameters in patients. In summary, carriers of IL-8 -251 T allele may have increased susceptibility to MS because of their differences in neuron survival or increased chances of viral persistence compared to carriers of A allele.

CSF cytokine and chemokine profiles in acute disseminated encephalomyelitis

We simultaneously measured 16 cytokines/chemokines in cerebrospinal fluid (CSF) from 14 patients with acute disseminated encephalomyelitis (ADEM) and 20 controls using a fluorescent bead-based immunoassay. A variety of cytokines, such as IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IFN-gamma, TNF-alpha, G-CSF and MIP-1beta, were significantly elevated in ADEM. In particular, G-CSF showed a marked 38-fold increase compared to the control mean. Significant positive correlations with inflammatory parameters in CSF, such as cell counts and protein levels, were found for IFN-gamma, IL-6 and IL-8. In contrast, IL-17 produced by activated CD4(+) memory T cells was not increased. The results suggested that various cytokines related to activation of macrophages/microglias and Th(1) and Th(2) cells are upregulated in CSF in ADEM.

Upregulation of vascular growth factors in multiple sclerosis: Correlation with MRI findings

Vascular permeability changes precede the development of demyelinating lesions in multiple sclerosis (MS), and vessel wall thickening and capillary proliferation are frequently seen in autopsied MS lesions. Although vascular growth factors are critical for inducing such vascular changes, their involvement in MS has not been extensively studied. Thus, we examined the involvement of various vascular growth factors in MS according to their clinical phase and subtype. We measured serum levels of vascular endothelial growth factor (VEGF), acidic and basic fibroblast growth factors (FGF) and platelet-derived growth factors (PDGFs)-AA, -AB and -BB in 50 patients with MS (27 opticospinal MS and 23 conventional MS patients) and 33 healthy controls using sandwich enzyme immunoassays. Correlations between growth factor changes and brain and spinal cord MRI findings were then analyzed. Serum VEGF concentrations were significantly higher in MS patients in relapse than in controls (p = 0.0495) and in MS patients in remission (p = 0.0003), irrespective of clinical subtype. Basic FGF was significantly increased in conventional MS patients, but not opticospinal MS patients compared with controls (p = 0.0291), irrespective of clinical phase. VEGF at relapse showed a significant positive correlation with the length of spinal cord lesions on MRI (r = 0.506, p = 0.0319). The results suggest that an increase in serum VEGF concentration might be involved in MS relapse and the formation of longitudinally extensive spinal cord lesions.

Progrès récents concernant les mécanismes immunitaires de la sclérose en plaques

INTRODUCTION

Multiple sclerosis (MS) is a heterogeneous disease. From an immunological point of view, it is considered an inflammatory TH1-mediated autoimmune disease of unknown origin, targeting myelin proteins.

STATE OF ART

Neuropathological analysis of MS lesions classified different clinical MS types according to the preponderance of different subsets of immune cells in the lesions (clinico-pathological correlation). Ex vivo analysis of various immunological parameters (like cytokines, antigenic targets) and MRI findings suggest a heterogeneous process leading to the autoimmune destruction of the myelin sheath. Clinical therapeutic trials, especially those using monoclonal antibodies, have recently improved our understanding of the immunology of MS, by focusing our interest on molecules modulating the reactivity of T or B cells, and on the influence of adhesion molecules on relapsing remititing MS. Finally, large scale transcriptional analysis of MS and EAE lesions gave a large amount of information about molecules that are up or down regulated during the disease process, and identified new candidates like osteopontin, which ended up being a key proinflammatory molecule influencing the course of the disease and a therapeutic target for EAE.

PERSPECTIVES

Investigating the numerous MS and EAE large scale transcriptional profiles will allow new hypotheses to arise, especially in the immunological field of MS. The relationship between inflammation and axonal loss is one of the key questions raised by researchers, and whether these two processes are directly related or not is still debated today.

CONCLUSION

A better understanding of the immunology of MS would lead to the discovery of new therapeutic and biological tools, allowing practical improvement of MS patient care.