The major histocompatibility complex, the immune system and multiple sclerosis

Statins as potential therapeutic agents in multiple sclerosis

3-Hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors (ie, statins) are oral cholesterol-lowering drugs. Statins are well tolerated and have an excellent safety record. These agents competitively inhibit HMG CoA reductase, which is the enzyme that catalyzes the conversion of HMG CoA to L-mevalonate. Although L-mevalonate is a key intermediate in cholesterol synthesis, several of its metabolites are involved in post-translational modification of specific proteins involved in cell proliferation and differentiation. Thus, independent of their cholesterol-reducing properties, statins have important pleiotropic biologic effects. Recent reports indicate that statins have anti-inflammatory and neuroprotective properties. Whether statins will be of clinical benefit for patients with multiple sclerosis and other neurodegenerative diseases of the central nervous system will only be known after they are evaluated in prospective randomized clinical trials.

Approved and future pharmacotherapy for multiple sclerosis

BACKGROUND

Pharmacotherapy for relapsing-remitting multiple sclerosis (MS) advanced with the demonstration that interferon beta and glatiramer acetate improve the clinical course of this disease. Mitoxantrone is the first drug approved by the Food and Drug Administration for treatment of secondary progressive MS. Despite this progress, the agents presently available are only partially effective, are difficult to administer, and may have significant side effects. Several orally administered immunomodulatory agents are presently being evaluated for treatment of MS. One class of drugs, HMG CoA inhibitors (statins), is safe and well-tolerated and could become another mainstay of MS therapy.

REVIEW SUMMARY

This article reviews the clinical evidence for approved MS therapies and discusses their mechanisms of action. Furthermore, the clinical and laboratory data suggesting a potential role for statins in MS therapy are discussed.

CONCLUSIONS

Although treatment with interferon beta, glatiramer acetate, and mitoxantrone, the approved therapies, provide important treatment options for patients with relapsing-remitting MS and secondary progressive MS, the potential benefits of other medications, including statins, should be explored in controlled clinical trials.

T-lymphocyte subsets modifications in multiple sclerosis: correlation with clinical disease activity

Serial analyses of peripheral blood T-lymphocyte subsets were performed in 280 samples collected over a 27 months period from 14 multiple sclerosis patients. A significant decrease of T8+ cells was found in 47.1% (47/87) of blood samples collected within four weeks of onset of a relapse opposed to 2.1% (1/47) of samples collected during the four weeks before a relapse and to 3.4% (5/146) of those collected over four weeks after a relapse. Changes of T-cells subsets appear to correlate with disease activity, but normal findings observed before relapses suggest that the decrease of T8+ cells cannot be used as valid predictor of relapse.

A serial study of peripheral blood T lymphocyte subsets in relapsing-remitting multiple sclerosis

Twelve patients with relapsing-remitting multiple sclerosis and 3 control subjects were evaluated weekly for six months. Peripheral blood lymphocyte subsets were enumerated using monoclonal antibodies and analysis with a dual-laser fluorescence-activated cell sorter. Results were correlated with clinically assessed disease activity. Fluctuations occurred in the number of T lymphocytes (Leu 1+) and cells with the helper/inducer phenotype (Leu 3a/OKT4+) in both patients and controls. Fluctuations in the number of cells with the suppressor/cytotoxic (Ts/c) cell phenotype (OKT5, OKT8, Leu 2a+) also occurred. Variations in the relative numbers of cells labeled with all three Ts/c monoclonals did occur, but with OKT5 generally labeling fewer cells than OKT8 or anti-Leu 2a. When findings were correlated with disease activity, OKT5 was a more sensitive gauge of disease activity than either OKT8 or anti-Leu 2a. When peripheral blood lymphocyte subsets were correlated with disease activity, the following patterns were observed: a reduction in the number of Ts/c cells without evidence of clinical disease (four episodes), the development of new symptoms suggestive of an acute relapse but without a reduction in the number of Ts/c cells (two episodes), and a reduction in the number of Ts/c cells associated with acute relapse (two episodes). In the two patients with acute relapse and a reduction in the number of Ts/c cells, clinical disease preceded a reduction in the number of Ts/c cells in 1 patient, whereas the two events occurred simultaneously in the other patient. Taken together, these limited results indicate that in some cases a reduction in the number of Ts/c cells may be the result rather than the cause of disease activity and may represent an epiphenomenon.

Suppressor T-lymphocytes in multiple sclerosis: analysis of patients with acute relapsing and chronic progressive disease

T cell-specific antigens as identified by the anti-Leu 1, anti-Leu 2a, and anti-Leu 3a monoclonal antibodies were quantitated in 31 normal control subjects, 21 adults with spinal cord injury, 58 patients with stable multiple sclerosis, 31 patients with chronic progressive multiple sclerosis, and 15 patients with multiple sclerosis in acute relapse. The only significant deviations from normal values were a slightly low mean T cell (Leu 1-positive) value in patients in acute relapse and a low suppressor T cell (Leu 2a-positive) mean value in patients with chronic progressive multiple sclerosis. We were unable to confirm previous studies using the OK series of monoclonal antibodies that reported low suppressor T cell levels (OKT5 and OKT8 positive) in patients with acute relapses. We suggest that modulation (a spontaneous or induced variability in the expression) of individual cell surface antigens may explain the differences seen between our study and other reported series.