Marcin P. Mycko

Multiple Sclerosis Severity Score Using disability and disease duration to rate disease severity

Background: There is no consensus method for determining progression of disability in patients with multiple sclerosis (MS) when each patient has had only a single assessment in the course of the disease. Methods: Using data from two large longitudinal databases, the authors tested whether cross-sectional disability assessments are representative of disease severity as a whole. An algorithm, the Multiple Sclerosis Severity Score (MSSS), which relates scores on the Expanded Disability Status Scale (EDSS) to the distribution of disability in patients with comparable disease durations, was devised and then applied to a collection of 9,892 patients from 11 countries to create the Global MSSS. In order to compare different methods of detecting such effects the authors simulated the effects of a genetic factor on disability. Results: Cross-sectional EDSS measurements made after the first year were representative of overall disease severity. The MSSS was more powerful than the other methods the authors tested for detecting different rates of disease progression. Conclusion: The Multiple Sclerosis Severity Score (MSSS) is a powerful method for comparing disease progression using single assessment data. The Global MSSS can be used as a reference table for future disability comparisons. While useful for comparing groups of patients, disease fluctuation precludes its use as a predictor of future disability in an individual.

microRNA-301a regulation of a T-helper 17 immune response controls autoimmune demyelination

MicroRNAs (miRNAs) are an emerging group of short, noncoding RNAs that play an important role in regulating expression of classical genes. Thus far little is known about their role in autoimmune demyelination. In this study, we analyzed changes in the miRNA profile in CD4+ T cells that occurred during the recognition of the myelin autoantigen, MOG35–55. We found that, both in vivo and in vitro, myelin antigen stimulation resulted in significant up-regulation of miR-301a, miR-21, and miR-155. Furthermore, these three miRNAs were overexpressed in T cells infiltrating the CNS in animals with experimental autoimmune encephalomyelitis. Use of specific miRNA antagonists, antagomirs, revealed that miR-301a contributed to the development of the T-helper type 17 subset via targeting the IL-6/23–STAT3 pathway. This contribution appeared to be mediated by the miR-301a effect on the expression of the PIAS3, a potent inhibitor of the STAT3 pathway. Manipulation of miR-301a levels or PIAS3 expression in myelin-specific CD4+ T cells led to significant changes in the severity of experimental autoimmune encephalomyelitis. Thus, we have identified a role of miR-301a in regulating the function of myelin-reactive T-helper type 17 cells, supporting a role for miR-301a and PIAS3 as candidates for therapeutic targets for controlling of autoimmune demyelination.

Multiple sclerosis: the frequency of allelic forms of tumor necrosis factor and lymphotoxin-alpha

The cytokines LTa and TNF have been implicated as major mediators of tissue injury in multiple sclerosis (MS). In this study we have assessed the frequency of specific polymorphisms for these genes in MS (n = 53) and controls (n = 81) using a highly sensitive, two stage nested polymerase chain reaction (PCR), with the second stage using mutation-specific primers. Genomic DNA was extracted from blood cells and the results confirmed by direct dideoxy chain termination sequencing. The frequency of the -308 G to A mutation in the TNF promoter region in normal controls was 15% and in MS was 24%. For LTa gene the exon 3 polymorphism allele A was detected in 36% of controls and 34% of the MS patients. In MS, the combined genotype TNF G + A and LTa C + C was present 6 times more frequently (12%) than in controls (2%), and patients with this genotype showed the highest EDSS scores. We found the TNF and LTa polymorphisms to occur independently from the HLA class II DR2 allele distribution in MS. Whilst the G - A polymorphism in TNF gene promoter has been studied previously in MS, with conflicting results, this is the first study that has addressed the exon 3 polymorphism in LTa in MS. The results indicate that this polymorphism is not linked with the higher genetic predisposition for MS, but that combined TNF G + A and LTa C + C genotype might contribute to development of the disease.

Inducible Heat Shock Protein 70 Promotes Myelin Autoantigen Presentation by the HLA Class II

In this study, we investigated the role of the inducible form of heat shock protein 70 (hsp70) in the presentation of the major putative autoantigen in multiple sclerosis, myelin basic protein (MBP), in the context of appropriate MHC class II. By coimmunoprecipitation, we found that MBP is associated with hsp70 in APC in an ATP/ADP-dependent manner. Additionally, using confocal microscopy, hsp70 was detected in the endocytic pathway of APC, where it colocalized with MBP and HLA-DR. The immunodominant epitopes of MBP 85–99 and 80–99 were shown to bind selectively and specifically to hsp70 by surface plasmon resonance. The functional significance of MBP interaction with hsp70 was demonstrated by the detection of enhanced responses of an MBP-specific T cell hybridoma to MBP and MBP 80–99 with increasing levels of hsp70 and reduced responses when hsp70 expression was diminished within APC-expressing DRA*0101, DRB1*1501 (DR1501). However, when MBP 85–99 was used as the stimulus, T cell hybridoma responses were not enhanced by hsp70 overexpression within APC, suggesting that hsp70 contributes to Ag processing rather than Ag presentation. The importance of a direct association between MBP and hsp70 in the presentation pathways was demonstrated by enhanced efficacy of MBP presentation by APC transfected with a plasmid vector encoding a fusion hsp70-MBP protein. This is the first report on the involvement of self-inducible hsp70 in MHC class II-dependent autoantigen processing by APC. It implicates that aberrant self hsp expression may lead to the enhancement/modulation of autoimmune responses.

Microarray gene expression profiling of chronic active and inactive lesions in multiple sclerosis

Multiple sclerosis, a primary autoimmune disease of the central nervous system has been characterized by the presence of the demyelinating lesions (plaques) in the CNS. To further understand the gene transcription status of the two most common lesions, chronic active and chronic inactive, we have performed a cDNA microarray analysis of these two lesion type. Comparative analysis of differential gene expression of chronic active and inactive lesions have confirmed the existence of a significant difference in the transcriptional profiles of these two lesion types in both marginal and central areas. Different sets of genes were highlighted, including genes of inflammatory characteristics, apoptosis related and stress-induced, indicating their potential role in MS pathogenesis.

γδ T Cells Enhance the Expression of Experimental Autoimmune Encephalomyelitis by Promoting Antigen Presentation and IL-12 Production

Using an adoptive transfer model of experimental autoimmune encephalomyelitis (EAE) induced by myelin basic protein (MBP)-reactive lymph node cells (LNC), we have shown that depletion of γδ T cells from LNC resulted in diminished severity of EAE in recipient mice, both clinically and histopathologically. The reduced potency of γδ T cell-depleted LNC to induce EAE correlated with decreased cell proliferation in response to MBP. The γδ T cell effect upon the threshold of MBP-induced LNC proliferation and EAE transfer was restored by reconstitution of γδ T cells derived from either MBP-immunized or naive mice, indicating that this effect was not Ag specific. The enhancing effect of γδ T cells on MBP-induced proliferation and EAE transfer required direct cell-to-cell contact with LNC. The γδ T cell effect upon the LNC response to MBP did not involve a change in expression of the costimulatory molecules CD28, CD40L, and CTLA-4 on TCRαβ+ cells, and CD40, CD80, and CD86 on CD19+ and CD11b+ cells. However, depletion of γδ T cells resulted in significant reduction in IL-12 production by LNC. That γδ T cells enhanced the MBP response and severity of adoptive EAE by stimulating IL-12 production was supported by experiments showing that reconstitution of the γδ T cell population restored IL-12 production, and that γδ T cell depletion-induced effects were reversed by the addition of IL-12. These results suggest a role for γδ T cells in the early effector phase of the immune response in EAE.

High incidence of spontaneous disease in an HLA-DR15 and TCR transgenic multiple sclerosis model

Multiple sclerosis (MS) is thought to involve CD4 T cell recognition of self myelin, many studies focusing on a pathogenic role for anti-myelin, HLA-DR15-restricted T cells. In experimental allergic encephalomyelitis, it is known which epitopes trigger disease and that disease is associated with determinant spread of T cell reactivity. Characterization of these events in human MS is critical for the development of peptide immunotherapies, but it has been difficult to define the role of determinant spread or define which epitopes might be involved. In this study, we report humanized transgenic mice, strongly expressing HLA-DR15 with an MS-derived TCR; even on a RAG-2 wild-type background, mice spontaneously develop paralysis. Disease, involving demyelination and axonal degeneration, correlates with inter- and intramolecular spread of the T cell response to HLA-DR15-restricted epitopes of myelin basic protein, myelin oligodendrocyte glycoprotein, and αB-crystallin. Spread is reproducible and progressive, with two of the epitopes commonly described in responses of HLA-DR15 patients. The fact that this pattern is reiterated as a consequence of CNS tissue damage in mice demonstrates the value of the transgenic model in supplying an in vivo disease context for the human responses. This model, encompassing pathologically relevant, spontaneous disease with the presentation of myelin epitopes in the context of HLA-DR15, should offer new insights and predictions about T cell responses during MS as well as a more stringent test bed for immunotherapies.

Suppression of experimental autoimmune encephalomyelitis with a TNF binding protein (TNFbp) correlates with down-regulation of VCAM-1/VLA-4

The effect of a novel TNF binding protein (TNFbp), a polyethylene glycol‐linked form of the type I soluble receptor of TNF, on the expression of adhesion molecules has been investigated with a passive transfer model of experimental autoimmune encephalomyelitis (EAE) in SJL/J mice. The expression of L‐selectin, VLA‐4 and LFA‐1 on spleen cells of EAE animals treated with TNFbp or saline was examined by FACS analysis. The expression of VCAM‐1 and ICAM‐1 was investigated by immunochemistry in spinal cord tissue of SJL/J mice with EAE. In animals sensitized for EAE and treated with TNFbp, the expression of VCAM‐1 in the central nervous system as well as VLA‐4 on spleen cells was clearly diminished. Reduction in VCAM‐1 staining and VLA‐4 expression corresponded to inhibition of inflammation in the spinal cord and to prevention of clinical signs of EAE. The results have also shown that myelin basic protein responses as well as non‐antigen‐specific responses were not diminished in animals treated with TNFbp. The findings suggest that TNFbp might prevent EAE development by modulating the expression of VCAM‐1 and VLA‐4.

Disease-related epitope spread in a humanized T cell receptor transgenic model of multiple sclerosis

While EAE has been an invaluable model for the immunopathogenesis of multiple sclerosis, it has sometimes been difficult to bridge the gap between findings and therapies in the rodent models and the cellular and molecular interactions that can be studied in the human disease. Humanized transgenic models offer a means of achieving this, through the expression of disease‐implicated HLA class II molecules, co‐expressed with a cognate HLA‐class II‐restricted, myelin‐specific TCR derived from a human T cell clone implicated in disease. We have generated such a transgenic line, called line 8, that co‐expresses a high level of HLA‐DR15 and a human TCR specific for HLA‐DR15/MBP 85–99. T cells from the transgenic line are skewed to the CD4 single‐positive compartment and produce IFN‐γ in response to peptide from mylein basic protein. Mice develop a spontaneous disease phenotype, showing poverty of movement, although this rarely develops into paralysis except following immunization with peptide. On induction of paralysis by immunization with peptide, disease correlates with epitope spread to a number of additional, HLA‐DR15‐restricted myelin epitopes. This model should be valuable for analyzing epitope spread in a humanized immunogenetic environment and for the testing of specific immunotherapies.

A heat shock protein gene (Hsp70.1) is critically involved in the generation of the immune response to myelin antigen

Protracted inflammation has been associated with the generation of autoimmune responses. In this respect, increase in the chaperonin, heat shock protein 70 (hsp70) is an outcome of prolonged inflammatory stress. Previous experiments have shown that overexpression of inducible hsp70 in vitro enhanced myelin autoantigen recognition. To prove the role of hsp70 in myelin‐directed responses in vivo, we applied a mouse deficient in the major gene encoding inducible hsp70, hsp70.1. Hsp70.1–/– mice sensitized for experimental autoimmune encephalomyelitis (EAE) with myelin oligodendrocyte glycoprotein (MOG) peptide 35–55, displayed almost complete resistance to the disease. This correlated with the loss of T cell proliferation and IFN‐γ production in response to MOG35–55. T cell transfer experiments as well as antigen presentation assays in vitro demonstrated that hsp70 deficiency was associated with dysfunction in the activation of autoreactive T cells. Moreover, T cell responses to ovalbumin (OVA) peptide 323–339 were altered and CD4+ T cells were more prone to TCR‐induced apoptosis, suggesting broader spectrum of T cell defect in hsp70.1–/– mice. These results provide compelling evidence for generalized effect mediated by inducible hsp70 in the recognition of myelin self and non‐self antigens that influences the cytokine profile of the immune response affecting autoimmune demyelination.