Protective effect of Lactobacillus reuteri DSM 17938 against experimental necrotizing enterocolitis is mediated by toll-like receptor 2

Lactobacillus reuteri DSM 17938 (LR 17938) has been shown to reduce the incidence and severity of necrotizing enterocolitis (NEC). It is unclear if preventing NEC by LR 17938 is mediated by toll-like receptor 2 (TLR2), which is known to mediate pro-inflammatory responses to bacterial cell wall components. NEC was induced in newborn TLR2-/- or WT mice by the combination of gavage-feeding cow milk-based formula and exposure to hypoxia and cold stress. Treatment groups were administered formula supplemented with LR 17938 or placebo (MRS media). We observed that LR 17938 significantly reduced the incidence of NEC, and reduced the percentage of activated effector CD4+T cells, while increasing Foxp3+ regulatory T cells in the intestinal mucosa of WT mice with NEC, but not in TLR2-/- mice. Dendritic cell (DC) activation by LR17938 was mediated by TLR2. The percentage of tolerogenic DCs in the intestine of WT mice was increased by LR 17938 during NEC, a finding not observed in TLR2-/- mice. Furthermore, gut level...