Lactobacillus reuteristrains reduce incidence and severity of experimental necrotizing enterocolitis via modulation of TLR4 and NF-κB signaling in the intestine

Abstract

Necrotizing enterocolitis (NEC) is the leading gastrointestinal cause of mortality and morbidity in the premature infant. Premature infants have a delay in intestinal colonization by commensal bacteria and colonization with potentially pathogenic organisms. Lactobacillus reuteri is a probiotic that inhibits enteric infections, modulates the immune system, and may be beneficial to prevent NEC. In previous studies, L. reuteri strains DSM 17938 and ATCC PTA 4659 differentially modulated inflammation in vitro; however, the strains had equivalent anti-inflammatory responses in LPS feeding-induced ileitis in neonatal rats in vivo. The impact of these two strains in the prevention of NEC has not been previously investigated. NEC was induced in newborn rats by orogastric formula feeding and exposure to hypoxia. L. reuteri was added to the formula to prevent NEC. NEC score, Toll-like receptor (TLR)-signaling genes, phospho-IκB activity, and cytokine levels in the intestine were examined. Both strains significantly increased survival rate and decreased the incidence and severity of NEC, with optimal effects from DSM 17938. In response to probiotic, mRNA expression of IL-6, TNF-α, TLR4, and NF-κB was significantly downregulated, while mRNA levels of anti-inflammatory cytokine IL-10 were significantly upregulated. In parallel, L. reuteri treatment led to decrease intestinal protein levels of TLR4 and cytokine levels of TNF-α and IL-1β in newborn rats with NEC. Both strains significantly inhibited not only intestinal LPS-induced phospho-IκB activity in an ex vivo study but also decreased the levels of phospho-IκB in the intestines of NEC rat model. Cow milk formula feeding produced a similar but milder proinflammatory profile in the intestine that was also ameliorated by 17938. Our studies demonstrate that each of the two L. reuteri strains has potential therapeutic value in our NEC model and in enteritis associated with cow milk feeding. These results support the concept that L. reuteri may represent a valuable treatment to prevent NEC.

Lactobacillus reuteri DSM 17938 differentially modulates effector memory T cells and Foxp3+ regulatory T cells in a mouse model of necrotizing enterocolitis

“…LR17938 inhibits pathogen growth and modulates the immune system. In this study the protective effects of the probiotic LR17938 on the survival, incidence, and severity of NEC in a mouse model further validated our previous observations in a rat NEC model (27,29). In addition, previous studies indicated that the frequency of gut Foxp3 ϩ Treg cells was decreased in NEC but reverted to normal following LR17938 treatment (27).…”

“…Two plasmids harboring antibiotic resistance genes were removed from strain 55730 to obtain strain 17938 (46), which inhibits pathogen growth and modulates the immune system. We have shown that feeding LR17938 to newborn rats produced a strong anti-inflammatory effect (28,29), reducing the incidence and severity of NEC (29) while increasing the frequency of Treg cells in the intestinal mucosa (27).…”

Bacillus Coagulans Enhance the Immune Function of the Intestinal Mucosa of Yellow Broilers

“…Liu also verified that Roy's lactobacillus DSM 17938 rat NEC has a positive effect on the prevention on rat NEC, which can significantly reduce the mRNA expression of TNF alpha and TLR 4 and TNF alpha, TLR 4 protein levels (Liu et al, 2012). Rajput verified that boundens yeast and bacillus B10 stimulated chicken bone marrow dendritic cells, increasing TLR 1, TLR 2, TLR 4, and TLR 15 expression (Rajput et al, 2014).…”

Probiotics and necrotizing enterocolitis

“…However, alteration of gut flora is only one potential mechanism by which probiotics might prevent NEC. Other mechanisms include effects on the gut immune system and via TLR-related signaling [76,77] and effects on mucosal integrity and intestinal permeability [78,79]. However, whether these are primary or secondary effects is extremely difficult to dissect, as the microbiome, immune system, mucosal integrity and gut barrier function are all mutually interdependent.…”