CD4 and inflammatory bowel disease: Complementary in vitro evidence confirms butyrate’s preferential differentiation of naïve CD4 + T cells from Inflammatory bowel disease (IBD) patients toward Tregs rather than Th17 lineages (Wen et al., 2021) - a shift proven critical for restoring mucosal immune tolerance (Lv et al., 2018; Tong et al., 2021).