Baseline T cell reactivity in multiple sclerosis is correlated to efficacy of interferon-beta

Role of Natural Killer Cells in Multiple Sclerosis

Although the etiology of multiple sclerosis (MS) is not known, the consensus is that Th1 cells sensitized to myelin proteins in the periphery are recruited into the CNS and damage the myelin sheath. Natural killers (NK) are cells that spontaneously lyse tumor target cells and have immunoregulatory activity secreting multiple cytokines and chemokines, as well as interacting with cells of innate and adaptive immune systems. A great discovery in the field is the cloning of several inhibitory and activating receptors. Another important contribution is the discovery that these cells express many seven-transmembrane-spanning domain receptors which aid them in extravasations into injured tissues. Despite all this progress, the role of NK cells in autoimmune diseases including MS is still not quite clear. In this paper, I will summarize recent findings related to the effects of these cells in both MS and the animal model of experimental autoimmune encephalomyelitis (EAE). Hence, I will discuss the effects of drugs used to treat MS/EAE and then explain their effects on NK cells. These include anti-CD25 or daclizumab, interferon-β (IFN-β), natalizumab, glatiramer acetate (GA), and fingolimod (FTY720). Finally, I will explain the contribution of the recently discovered NK17/NK1 cells in MS disease.

The ex vivo production of IL-6 and IL-21 by CD4+ T cells is directly associated with neurological disability in neuromyelitis optica patients

Neuromyelitis optica (NMO), also known as Devic's disease, is an autoimmune, inflammatory disorder of the central nervous system (CNS) in which the immune system attacks myelin of the neurons located at the optic nerves and spinal cord, thus producing a simultaneous or sequential optic neuritis and myelitis. The objective of this study was evaluated the background T-cell function of patients suffering from neuromyelitis optica (NMO), an autoimmune disorder of the central nervous system. In our study, the in vitro T cell proliferation and the production of Th1 cytokines were significantly lower in cell cultures from NMO patients, as compared with healthy individuals. In contrast, a dominant Th17-like phenotype, associate with higher IL-23 and IL-6 production by LPS-activated monocytes, was observed among NMO patients. The release of IL-21 and IL-6 by polyclonally activated CD4+ T cells was directly correlated to neurological disability. In addition, the in vitro release of IL-21, IL-6 and IL-17 was significantly more resistant to glucocorticoid inhibition in NMO patients. In conclusion, the results indicate dominant Th17-related response in NMO patients that was directly proportional to neurological disability. Furthermore, our results can help to explain why NMO patients trend to be more refractory to corticoid treatment.

Diminished myelin-specific T cell activation associated with increase in CTLA4 and Fas molecules in multiple sclerosis patients treated with IFN-beta

Multiple sclerosis (MS) is a chronic inflammatory disease of the white matter of the central nervous system (CNS) characterized by focal areas of demyelination. Interferon-beta (IFN-beta) provides an effective treatment that lessens the frequency and severity of exacerbations in relapsing-remitting multiple sclerosis (RRMS), but the mechanisms by which IFN-beta is efficient remain uncertain. The data presented here demonstrate that IFN-beta impairs the proliferative response to myelin basic protein (MBP) and myelin, as well as increasing the expression of the CTLA4 intracellular molecule. Moreover, this treatment increases the expression of surface Fas molecules and of the soluble form of these molecules. Our hypothesis is that the increase in Fas and CTLA4 molecules in MS patients may lead to lymphocyte apoptosis, which suggests possible mechanisms underlying the therapeutic response to IFN-beta.

Interferon-beta treatment for multiple sclerosis

Multiple sclerosis (MS) is the leading nontraumatic cause of neurologic disability in young adults. Interferon-beta, approved for use in 1993, was the first treatment to modify the course and prognosis of the disease and remains a mainstay of MS treatment. Numerous large-scale clinical trials in early, active patient populations have established the clinical efficacy of interferon-beta in reducing relapses and delaying disability progression. Although its mechanism of action remains incompletely understood, a reduction in active lesions seen on magnetic resonance imaging implies primary anti-inflammatory properties, a mechanism supported by basic immunologic research. Variation in individual patient responsiveness to interferon-beta may be due to disease variability or differential induction of interferon-stimulated genes. The magnitude of the therapeutic effect appears to be similar among products, but the optimal dose, route, and frequency of administration of the drug remain uncertain.

Adherence to interferon-beta treatment and results of therapy switching

Adherence to long-term therapy has always been a problem in all fields of medicine. In multiple sclerosis (MS), treatment consists of parenteral administration of immune-modulating drugs once or several times weekly for an as yet undetermined length of time. Different studies on the MS patients' compliance showed that the most frequent cause of stopping treatment is the perceived lack of efficacy and that most treatment withdrawals occur during the first year of treatment. A trial aimed to identify the minimum effective IFNbeta dose showed that some patients had disease activity after switching to a lower IFNbeta dose. OPTIMS (OPTimization of Interferon dose for MS study) was a multicenter study, involving 24 Italian MS centers, 216 patients, aimed to identify a treatment response indicator allowing the early identification of poorly responding patients. A single active scan during the first 6 months of IFN treatment had a significant positive predictability of 59% (95% confidence interval, 41-76; p=0.05) on the presence of clinical signs of disease activity during the further 2-year follow-up.

Janus faces of microglia in multiple sclerosis

Multiple sclerosis (MS) is the most common cause of neurological disability in young adults. The disease is characterized by inflammatory reactions, demyelination and axonal loss in the brain, spinal cord and optic nerves. Microglia seem to play an important role in the inflammatory processes in MS, since they are found in actively demyelinating lesions. Their role in the differentiation of T cells could led to the expansion of inflammation and tissue destruction. However, microglia are also involved in the termination of an inflammatory response and produce protective factors. To be able to therapeutically manipulate microglia, their exact function in the onset and development of MS needs to be clarified. This review provides an overview of the functions of the most important microglia-associated molecules in MS, being CD40, B7-1 and B7-2, interferon-gamma, tumor necrosis factor-alpha, chemokines, prostanoids, and nitric oxide.

Beneficial effect of interferon-β treatment in patients with multiple sclerosis is associated with transient increase in serum IL-6 level in response to interferon-β injection

In order to predict the clinical benefit of interferon-beta (IFN-beta) to patients with multiple sclerosis (MS), the following markers were investigated; (1) chronological change of cytokines (IFN-gamma, TNF-alpha, IL-6, IL-10, and TGF-beta) after administration of IFN-beta, (2) untoward effects of IFN-beta such as headache and arthralgia, (3) backgrounds of the patients such as age and relapse rate, (4) efficacy of IFN-beta therapy assessed by the change of relapse rate and progression of disability. Chronological blood sampling was performed 0, 10, and 24 h after injection of IFN-beta. The increase of serum IL-6 level in response to IFN-beta administration was associated with headache, arthralgia, relapse rate before treatment, and disability score at the initiation of the therapy. Significant association of change of serum TNF-alpha with age and headache was also observed. The important finding in this study was that patients with a transient increase in IL-6 in response to IFN-beta showed a slow disease progression. This result suggests that this transient increase in the serum IL-6 predicts favorable response to IFN-beta treatment.

Increased Spontaneous Ex Vivo Apoptosis and Subset Alterations in Peripheral Blood T Cells from Patients with Multiple Sclerosis

In order to characterize the immunophenotype and the lymphocyte apoptosis in multiple sclerosis (MS) patients, the peripheral blood lymphocytes of 46 MS patients and 12 healthy volunteers were studied by flow cytometry. Immunophenotypic alterations included significant increases in T CD4+ lymphocytes and reductions in the percentages of CD3+ and CD8+ T cells. After 24 h of culture spontaneous apoptosis was increased in almost T lymphocyte subsets from MS patients and it was significantly higher in those patients who had suffered more than two relapses in the two previous years. The incidence of spontaneous apoptosis was not dependent on FasL-Fas interactions and correlated with the percentages of cells positive for active caspases but not with percentages of Fas+ cells. The increased susceptibility to apoptosis of peripheral blood T lymphocytes from MS patients is difficult to reconcile with the previously proposed role of a defective lymphocyte apoptosis in the pathophysiology of MS.

Effects of interferon-β on microglial functions as inflammatory and antigen presenting cells in the central nervous system

Interferon-beta (IFNbeta) reduces exacerbations of the relapsing-remitting form of multiple sclerosis (MS), but the exact mechanisms by which it exerts its beneficial effects are unknown. In this study, we examined the effects of IFNbeta on microglial functions, as either antigen presenting cells or effector cells for inflammatory demyelination. IFNbeta significantly suppressed the expression of class II MHC antigen and the co-stimulatory molecule B7-1 in microglia. It also suppressed microglial IL-12 production and differentiation of myelin oligodendrocyte glycoprotein (MOG)-sensitized T cells into the T helper 1 phenotype, which use microglia as antigen presenting cells. However, IFNbeta significantly and dose-dependently enhanced the production of inflammatory mediators for demyelination, such as TNFalpha, IL-1beta, IL-6, and nitric oxide (NO). The upregulation of inflammatory mediators was effectively suppressed with a phosphodiesterase inhibitor. Thus, IFNbeta may exert its suppressive effects in the induction phase, but not in the effector phase of MS. Side effects of IFNbeta treatment may be due to elevation of pro-inflammatory cytokines, and may be reduced by co-treatment with phosphodiesterase inhibitors.

Defining interferon ? response status in multiple sclerosis patients

IFN-beta is effective in reducing relapses and magnetic resonance imaging (MRI) lesions in multiple sclerosis (MS). It is assumed that individual therapeutic responses vary, but methods to identify IFN-beta responsiveness have not been validated. Our objective was to evaluate methods to classify IFN-beta responder status using relapses and MRI lesions. Data was analyzed from 172 patients who were followed up in a placebo-controlled clinical trial of IFN-beta1a for 2 years. Patients were classified as responders or nonresponders using (1) the number of relapses during the 2-year trial; (2) the number of new T2 lesions after 2 years; and (3) the number of gadolinium-enhancing lesions at year 1 and year 2 on study. Outcomes included 2-year change in the Expanded Disability Status Scale, Multiple Sclerosis Functional Composite, and brain parenchymal fraction. We found that subgroups with high on-study relapse numbers had more disease progression, differences between responder subgroups were similar in the IFN-beta1a and placebo arms. In contrast, subgroups with high numbers of new MRI lesions had significantly more disease progression only in the IFN-beta1a arm. Baseline characteristics failed to account for differential outcome. New MRI lesion activity during IFN-beta1a treatment correlates with poor response to IFN-beta1a. MRI classification may facilitate rational therapeutic decisions, better clinical trial designs, and studies correlating biomarkers with therapeutic response.