Short-chain fatty acids and intestinal inflammation in Multiple Sclerosis – Modulation of female susceptibility by microbial products?
Abstract Background. Multiple Sclerosis (MS) is an autoimmune-mediated disease of the central nervous system. Experimental data also suggest a role of intestinal microbiota and microbial products such as short-chain fatty acids (SCFA) in the pathogenesis of MS. A recent clinical study reported beneficial effects (mediated by immunomodulatory mechanisms) after oral administration of the SCFA propionate in MS patients. Based on available evidence, we aimed to investigate whether SCFA and the fecal inflammation marker calprotectin are altered in MS. Methods. 76 subjects (41 patients with relapsing-remitting MS and 35 age-matched controls) were investigated in this case-control study. All subjects underwent clinical assessment with established scales and provided fecal samples for a quantitative analysis of fecal SCFA and fecal calprotectin concentration. Fecal markers were compared between MS patients and controls, and were analyzed for an association with epidemiological as well as clinical parameters. Results. Median fecal calprotectin concentrations remained within normal range without any group-specific differences. Fecal SCFA showed a non-significant reduction in MS patients, whereas female subjects showed significantly reduced SCFA concentrations compared to male subjects. Conclusions. In our cohort of MS patients, we found no evidence of an active intestinal inflammation. As the vast majority of patients, however, was under immunotherapy, this might have affected the outcome measures. The sex-associated difference in fecal SCFA concentrations might at least partially explain female predominance in MS. Large-scale longitudinal studies including drug-naïve MS patients are required to determine the role of SCFA in MS and to distinguish between disease-immanent effects and those caused by the therapeutic regime.