All individuals recruited for the study underwent EGD for diagnostic purposes. Exclusion criteria for both HCs and RRMS patients were treatment with antibiotics or corticosteroids in the 3 months before EGD and history of gastroenteritis, gastric ulcer, irritable bowel disease, celiac disease, inflammatory bowel disease, and gastric and colorectal cancers. All patients recruited in this study have a diagnosis of RRMS defined according to Poser’s diagnostic criteria. None of the RRMS patients received corticosteroids in the 3 months before the EGD. The mean age of healthy individuals was slightly higher than that of RRMS patients, but our correlative analysis did not reveal any association between age and TH17 cell percentages and Prevotella/Streptococcus relative abundance. All samples analyzed were donated for research purposes, and each subject signed an informed consent. Data are means ± SD, unless otherwise indicated. RR-NEDA, RRMS/NEDA; RR-EDA, RRMS/EDA.