Obesity and the risk of Multiple Sclerosis. The role of Leptin.

OBJECTIVE: To investigate the effects of leptin on different T-cell populations, in order to gain more insight into the link between leptin and obesity. METHODS: Three hundred and nine RRMS patients and 322 controls participated in a cross-sectional survey, to confirm whether excess weight/obesity in adolescence or early adulthood increased the risk of MS. Serum leptin levels were determined by ELISA. MBP83-102 , and MOG63-87 peptide-specific T cells lines were expanded from peripheral blood mononuclear cells. Leptin receptor expression was measured by RT-PCR and flow cytometry. Bcl-2, p-STAT3, pERK1/2, and p27kip1 expression were assayed using ELISA, and apoptosis induction was determined by Annexin V detection. Cytokines were assessed by ELISPOT and ELISA, and regulatory T cells (Tregs) by flow cytometry. RESULTS: Logistic regression analysis, showed excess weight at age 15, and obesity at 20 years of age increased MS risk (OR = 2.16, P = 0.01 and OR = 3.9, P = 0.01). Leptin levels correlated with BMI in both groups. The addition of Leptin increased autoreactive T-cell proliferation, reduced apoptosis induction, and promoted proinflammatory cytokine secretion. Obese patients produced more proinflammatory cytokines compared to overweight/normal/underweight subjects. Inverse correlation was found between leptin levels and circulating Treg cells (r = -0.97, P < 0.0001). Leptin inhibited Treg proliferation. Effects of leptin on CD4+ CD25- effector T cells were mediated by increased STAT3 and ERK1/2 phosphorylation, and down modulation of the cell cycle inhibitor P27kip1 . In contrast, leptin effects on Tregs resulted from decreased phosphorylation of ERK1/2 and upregulation of p27kip1 . INTERPRETATION: Leptin promotes autoreactive T-cell proliferation and proinflammatory cytokine secretion, but inhibits Treg-cell proliferation.

Melatonin Contributes to the Seasonality of Multiple Sclerosis Relapses.

Seasonal changes in disease activity have been observed in multiple sclerosis, an autoimmune disorder that affects the CNS. These epidemiological observations suggest that environmental factors influence the disease course. Here, we report that melatonin levels, whose production is modulated by seasonal variations in night length, negatively correlate with multiple sclerosis activity in humans. Treatment with melatonin ameliorates disease in an experimental model of multiple sclerosis and directly interferes with the differentiation of human and mouse T cells. Melatonin induces the expression of the repressor transcription factor Nfil3, blocking the differentiation of pathogenic Th17 cells and boosts the generation of protective Tr1 cells via Erk1/2 and the transactivation of the IL-10 promoter by ROR-α. These results suggest that melatonin is another example of how environmental-driven cues can impact T cell differentiation and have implications for autoimmune disorders such as multiple sclerosis.

Low familial risks for multiple sclerosis in Buenos Aires, Argentina.

BACKGROUND: Multiple sclerosis is a complex disease in which genetic susceptibility plays a role and familial occurrence has long been recognized. To date, no studies of familial occurrence have been conducted in Argentina, a country with low to intermediate prevalence. METHODS: As part of a cross-sectional study on multiple sclerosis in Buenos Aires, immediate and extended pedigree details were collected on 219 patients. Crude and age-adjusted recurrence risks for patient relatives were also assessed. RESULTS: Details on age or age of death and disease status were obtained for 4227 relatives. Ten percent of patients reported at least one relative with MS diagnosis, the highest risk (1.54%) was observed in daughters of patients who presented 92-times greater risk than the general population. Sibling recurrence risk ratio was similar to that reported in other locations. CONCLUSIONS: Relatives of patients with MS living in Argentina are at greater risk of developing the disease, although not as high as the risk reported for other geographic regions.

Autoimmune disease prevalence in a multiple sclerosis cohort in Argentina.

Background. Comorbid autoimmune diseases in MS patients have been studied extensively with controversial results. Moreover, no such data exists for Latin-American MS patients. Methods. We conducted a case-control study aimed to establish the prevalence of autoimmune disorders in a cohort of Argentinean MS patients. Results. There were no significant differences in autoimmune disease prevalence in MS patients with respect to controls. The presence of one or more autoimmune disorders did not increase risk of MS (OR 0.85, 95% CI 0.6-1.3). Discussion. Our results indicate absence of increased comorbid autoimmune disease prevalence in MS patients, as well as of increased risk of MS in patients suffering from other autoimmune disorders.

Sex-specific environmental influences affecting MS development.

Vitamin D status, smoking, and Epstein-Barr virus infection (EBV) may all contribute to explain differences in disease prevalence and incidence of Multiple Sclerosis (MS). MS affects women more often than men, and recent cross-sectional study assessments provide evidence of increased female to male prevalence in relapsing remitting MS patients, suggesting that sex hormones may exert an active role in disease pathogenesis. Studies in both humans and animal disease models demonstrate a functional synergy for the immunomodulatory effects of Vitamin D3 and 17-ß estradiol. Both smoking and EBV infection clearly increase MS risk, and smoking history has also been associated with poorer disease prognosis. However, neither factor can explain the recent trend indicating greater female prevalence. Therefore, large population-based case-control studies from well defined geographic areas with homogeneous populations should be performed, in order to define environmental factor effects, and sex hormone influences, to better understand prevalence and incidence gender differences observed.