Lactobacillus reuteri CRL1098 soluble factors exert in vitro and in vivo anti-inflammatory effects

Abstract

Soluble factors produced by probiotic bacteria such as lactobacilli can modulate immune system responses. The aims of this study were to determine whether Lactobacillus reuteri CRL1098 soluble factors (LrS) were able to modulate in vitro the inflammatory response triggered by LPS in murine macrophages (RAW 264.7) and to evaluate in vivo their capacity to exert anti inflammatory actions in acute lung injury (ALI) induced by LPS in mice. In vitro assays demonstrated that LrS significantly reduced the production of pro inflammatory mediators (NO,COX-2,Hsp70) and pro inflammatory cytokines (TNFalpha, IL6) caused by the stimulation of macrophages with LPS. Results from flow cytometry assays revealed that LrS reduced apoptosis of LPS-challenged RAW cells. Bax expression was reduced while no significant difference was observed in Bcl-2 expression levels. In addition, the effect of LrS on NF-kappaB pathway was evaluated by immunofluorescence microscopy: inhibition of NF-kappaB translocation to the nucleus in LrS treated macrophages exposed to LPS was detected, as well as a reduction of Akt and increase of ERK phosphorylation. In vivo assays proved that the LPS induced secretion of the pro inflammatory cytokines, inflammatory cells recruitment to the airways and inflammatory lung tissue damage were reduced in LrS treated mice, providing a new way to reduce strong pulmonary inflammation.