Levels of peripheral Th17 cells and serum Th17-related cytokines in patients with multiple sclerosis: A meta-analysis

Background: Multiple reports have described the proportion of Th17 cells in peripheral blood and serum levels of Th17-related cytokines in patients with multiple sclerosis (MS). To clarify the status of Th17 cells and Th17-related cytokines in MS patients, we did a meta-analysis of the results published previously to assess the levels of peripheral Th17 cells and serum Th17-related cytokines in patients with MS. Methods: We searched Embase, PubMed, Cochrane, Web of Knowledge, FDA.gov, and Clinical Trials.gov systematically for studies reporting the proportion of Th17 cells and the serum levels of Th17-related cytokines (IL-17, IL23) in MS patients. Our main endpoints were the proportion of Th17 cells among CD4(+) T cells in peripheral blood (PB), serum IL-17 levels, and serum IL-23 levels. We assessed pooled data by using a random-effects model. It has been registered at International Prospective Register of Systematic Reviews (PROSPERO) (number CRD42017059113). Results: Of 560 identified studies, a total of 12 studies were selected in our analysis. Compared with control subjects, MS patients had a higher proportion of Th17 cells [1.37, (0.53, 2.21)] in PB, an elevated levels of serum IL-17 [2.48, (1.25, 3.71)] and an increased IL-23 levels in serum [2.29, (0.58, 4.00)]. Conclusion: Under random effect model of meta-analysis, the data showed that the proportion of Th17 cells in PB and levels of serum IL-17 and IL-23 increased among MS patients compared to control subjects. This result demonstrated that Th17 cells and Th17-related cytokines may be involved in the pathogenic mechanisms of MS.