Lactobacillus rhamnosus (LGG) Regulates IL-10 Signaling in the Developing Murine Colon through Upregulation of the IL-10R2 Receptor Subunit

Abstract

The intestinal microflora is critical for normal development, with aberrant colonization increasing the risk for necrotizing enterocolitis (NEC). In contrast, probiotic bacteria have been shown to decrease its incidence. Multiple pro- and anti-inflammatory cytokines have been identified as markers of intestinal inflammation, both in human patients with NEC and in models of immature intestine. Specifically, IL-10 signaling attenuates intestinal responses to gut dysbiosis, and disruption of this pathway exacerbates inflammation in murine models of NEC. However, the effects of probiotics on IL-10 and its signaling pathway, remain poorly defined. Real-time PCR profiling revealed developmental regulation of MIP-2, TNF-α, IL-12, IL-10 and the IL-10R2 subunit of the IL-10 receptor in immature murine colon, while the expression of IL-6 and IL-18 was independent of postnatal age. Enteral administration of the probiotic Lactobacillus rhamnosus GG (LGG) down-regulated the expression of TNF-α and MIP-2 and yet failed to alter IL-10 mRNA and protein expression. LGG did however induce mRNA expression of the IL-10R2 subunit of the IL-10 receptor. IL-10 receptor activation has been associated with signal transducer and activator of transcription (STAT) 3-dependent induction of members of the suppressors of cytokine signaling (SOCS) family. In 2 week-old mice, LGG also induced STAT3 phosphorylation, increased colonic expression of SOCS-3, and attenuated colonic production of MIP-2 and TNF-α. These LGG-dependent changes in phosphoSTAT3, SOCS3, MIP-2 and TNF-α were all inhibited by antibody-mediated blockade of the IL-10 receptor. Thus LGG decreased baseline proinflammatory cytokine expression in the developing colon through upregulation of IL-10 receptor-mediated signaling, most likely due to the combined induction of phospho-STAT3 and SOCS3. Furthermore, LGG-dependent increases in IL-10R2 were associated with reductions in TNF-α, MIP-2 and disease severity in a murine model of intestinal injury in the immature colon.

The role of intestinal epithelial barrier function in the development of NEC

“…31 The potential mechanisms by which probiotics may prevent NEC have been extensively studied in experimental animal models. 86,[104][105][106][107][108][109][110][111][112][113][114][115][116] Specifically, their effect on TJs has been studied by a number of laboratories. In 2009, Khailova, at al., published that oral administration of Bifidobacterium bifidum (Bb) decreased elevated protein levels of ileal occludin and claudin-3 observed in neonatal rats with NEC.…”

Proteobacteria-specific IgA regulates maturation of the intestinal microbiota

“…[49][50][51] Mice were sacrificed 2 h after PAF and LPS administration and mucosal injury was graded in a blinded-fashion using a scale as described previously 52 and below. Three experiments were performed with 4-6 mice in each group.…”

Modulation of immunity and inflammatory gene expression in the gut, in inflammatory diseases of the gut and in the liver by probiotics

“…Mucin 5ac (muc5ac) gene expression in gastric corpus samples and gastric mucin production in stomach samples from the B. bifidum BF-1 group, but not the S. thermophilus YIT 2021 group, were significantly higher than those in the respective samples from the vehicle group [86] . Mirpuri et al [87] (2012) evaluated the enteral administration of LGG in mice with intestinal injury due to the administration of platelet-activating factor (PAF) and LPS. The probiotic strain downregulated the expression of TNF-α and MIP-2 but failed to alter IL-10 mRNA and protein expression.…”