Experimental autoimmune encephalomyelitis: immunotherapy with anti-tumor necrosis factor antibodies and soluble tumor necrosis factor receptors.

Multiple sclerosis (MS) is a demyelinating disease in which an inflammatory cell infiltrate represents a characteristic pathologic feature of active lesions within the CNS. The possibility has been raised that cell-mediated immune mechanisms orchestrate the pathogenesis of MS. Cytokines play a particularly important role in cellular immune mechanisms. These soluble glycoproteins, nonimmunoglobulin in nature, act nonenzymatically to regulate immune cell function. A unique family of cytokines, the tumor necrosis factors (TNFs), demonstrate immunoregulatory activity but are also involved in the effector arm of cellular immune responses. Recently, studies both in vitro and in vivo have suggested a role for TNFs in the pathology of MS. This report summarizes data implicating TNFs in the mechanisms of MS and attempts to apply the anti-TNF approach in the future therapeutic strategy for this disease.

Shedding of TNF receptors in multiple sclerosis patients.

OBJECTIVE: To evaluate the rate of shedding of tumor necrosis factor (TNF) receptors (TNFRs) in MS patients. BACKGROUND: It was previously suggested that TNF might play a significant role in the immunopathologic mechanism of MS. TNF mediates its biologic effects by interacting with two distinct receptors: TNFR-p55 and TNFR-p75. Both of these receptors exist in soluble and membrane-bound forms. Soluble receptors have been shown to influence TNF activity in vitro and in vivo and maintain balance between active, free TNF and inactive form of this cytokine bound to its soluble receptors. METHODS: In the current study, the authors measured shedding of TNFRs from cell surface of peripheral blood mononuclear cells, peripheral blood lymphocytes, and monocytes in three groups of MS patients: relapsing-remitting in relapse, relapsing-remitting in remission, and chronic progressive. RESULTS: The authors observed a significant distortion in generation of both soluble TNF receptors. Whereas the TNFR-p55 was shed at lower rate compared with healthy volunteers, the shedding of TNFR-p75 was significantly higher in MS patients. CONCLUSION: Disturbance in TNFR shedding might contribute to the distortion of a fine balance between circulating TNF and its natural inhibitors in MS.

Alemtuzumab more effective than interferon ß-1a at 5-year follow-up of CAMMS223 clinical trial.

OBJECTIVE: To report the long-term safety and efficacy results from CAMMS223 comparing alemtuzumab with interferon ß-1a in early, active relapsing-remitting multiple sclerosis (RRMS). What are the long-term effects of alemtuzumab treatment, received 36 to 48 months previously, on relapse and disability in early, active RRMS? This study provides evidence of the effectiveness of alemtuzumab in reducing the relapse rate and accumulation of disability compared with interferon ß-1a (IFNß-1a) through extended follow-up (up to 60 months from baseline). METHODS: Of 334 patients originally randomized, 198 participated in the extension phase (151 [68%] alemtuzumab and 47 [42%] IFNß-1a). Disability, relapses, and safety were assessed as in the original study period. Efficacy outcomes were analyzed from baseline of the original trial period to 60 months. Safety data extended beyond 60 months. RESULTS: Over 5 years, alemtuzumab lowered the risk of sustained accumulation of disability by 72% and the rate of relapse by 69% compared with IFNß-1a (both p < 0.0001). The annualized relapse rate from baseline to month 60 was 0.11 for alemtuzumab and 0.35 for IFNß-1a. Complete safety follow-up reflected 988 and 376 person-years for alemtuzumab and IFNß-1a patients, respectively. Serious infections were seen in 7% of alemtuzumab patients and 3% of IFNß-1a patients, and thyroid disorders were seen in 30% of alemtuzumab patients vs 4% of IFNß-1a patients. Immune thrombocytopenia occurred in 3% of alemtuzumab patients and 0.9% of IFNß-1a patients during the initial study period; no additional events were reported during the extension phase. One alemtuzumab patient developed Goodpasture disease 39 months after the second annual cycle of alemtuzumab. CONCLUSIONS: Through extended follow-up, alemtuzumab remained significantly more efficacious than IFNß-1a, with a safety profile consistent with previous reports. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that alemtuzumab is more effective than interferon ß-1a in reducing relapses and disability in patients with RRMS in a long-term follow-up of a rater-blinded, randomized clinical trial with 59.5% of patients participating in the extended follow-up period.

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.

Tumor necrosis factor mediates myelin and oligodendrocyte damage in vitro.

Recombinant human tumor necrosis factor (rhTNF) has been tested for its effect on myelinated cultures of mouse spinal cord tissue. As controls, recombinant human interferon gamma (rhIFN) and interleukin-2 (rhIL-2) were tested, as well as T-cell supernatants, antigalactocerebroside serum, and normal culture medium. It was found that rhTNF induced delayed-onset (18-24 hr) oligodendrocyte necrosis and a type of myelin dilatation peculiar to this system. Some nerve fibers progressed to demyelination by 72 hours. The myelin dilatation was not reversible by return to normal feeding solution for 3 days. In contrast, rhIFN, rhIL-2, T-cell supernatants, and normal medium had little or no effect on cultures. This mechanism differs from other immune-mediated mechanisms in that it appears that a physiological (not structural) demyelination occurs initially without overt destruction of the myelin sheath. These observations are relevant to the evolution of the multiple sclerosis plaque: dysfunction of ionic channels might contribute to the eventual demise of oligodendrocytes and axons in the longstanding lesion.

Proliferation of astrocytes in vitro in response to cytokines. A primary role for tumor necrosis factor.

The effect of cytokines on astrocytes cultured from mature bovine brain was determined both in a serum-containing medium and in a chemically-defined medium. The results showed that in serum-free medium, human TNF and, to a lesser degree, IL-6 and lymphotoxin, were mitogenic for astrocytes. Increased uptake of [3H]thymidine could be detected within 36 h in vitro and its presence in astrocytes was confirmed by autoradiography. In contrast, neither IL-1 alpha nor IL-1 beta induced astrocyte proliferation in serum-free medium but showed some synergistic effect with serum after 72 h. The proliferative effect of TNF and IL-6 was confirmed by cell counting. None of the cytokines tested was toxic for astrocytes as measured by 51Cr release. No mitogenic effect for oligodendroglia, purified from the same source, was detected. The results support a role for products of activated inflammatory cells in the development of astrocyte proliferation that may contribute to the reactive gliosis found in white matter diseases of the central nervous system such as multiple sclerosis.

Multiple sclerosis: the increased frequency of the ICAM-1 exon 6 gene point mutation genetic type K469.

Intracellular adhesion molecule-1 (ICAM-1) plays an important role in the cascade of adhesion events in the homing of inflammatory cells to the central nervous system (CNS) in experimental autoimmune encephalomyelitis (EAE) and in multiple sclerosis (MS). Two single-base ICAM-1 polymorphisms have been described, in exons 4 and 6, changing codons 241 and 469 in the ICAM-1 gene, respectively. Both polymorphisms result in amino acid changes and can potentially lead to different interactions of ICAM-1 with its ligands. To detect ICAM-1 gene polymorphisms in MS, we have developed a highly sensitive and site-specific, two-stage, nested polymerase chain reaction. Genomic DNA was extracted from blood cells of 79 MS patients and 68 control subjects. The results were confirmed by direct dideoxy chain termination sequencing. The frequency of exon 6 allele T was found to be significantly higher in MS patients than in controls (68% vs 49%). Most interesting, the frequency of exon 6 homozygote K469 was significantly higher in MS patients than in controls (53% vs 34%). Higher frequency of the K469 genotype was found to be independent of possible linkage with the previously described MS susceptibility factor, the HLA class II DR2 allele. In the present study, we have shown for the first time the ICAM-1 gene polymorphisms in MS. The results indicate increased frequency of ICAM-1 exon 6 allele T in MS patients, which may contribute to the MS genetics background.