A new article published in The Journal of Clinical Investigation reported that the attenuation of the incidence of necrotizing enterocolitis (NEC) by the consumption of human breast milk (HBM) correlates with alterations in the gut microbiota, particularly enrichment of Propionibacterium species. The results demonstrated that the transfaunation of microbiota from HBM-fed preterm infants or a newly identified and cultured Propionibacterium strain, P. UF1, to germfree mice rendered protection against pathogen infection and correlated with profound increases in intestinal T helper-17 (Th17) cells. The induction of Th17 cells was dependent on bacterial dihydrolipoamide acetyltransferase (DlaT) – a major protein expressed on the P. UF1 surface layer (S-layer). Furthermore, binding of P. UF1 to its cognate receptor, SIGNR1, on dendritic cells resulted in the regulation of intestinal phagocytes. Moreover, transfer of P. UF1 profoundly mitigated induced NEC-like injury in neonatal mice. The findings of this study confirmed the protective effects of HBM and P. UF1-induced immune-regulation, which safeguard against pro-inflammatory diseases, including NEC.1Reference1. Colliou N, Ge Y, Sahay B et al. Commensal Propionibacterium strain UF1 mitigates intestinal inflammation via Th17 cell regulation. Journal of Clinical Investigation. 2017. doi:10.1172/jci95376.