Oral administration of a probiotic Lactobacillus modulates cytokine production and TLR expression improving the immune response against Salmonella enterica serovar Typhimurium infection in mice

Abstract

BackgroundDiarrheal infections caused by Salmonella, are one of the major causes of childhood morbidity and mortality in developing countries. Salmonella causes various diseases that range from mild gastroenteritis to enteric fever, depending on the serovar involved, infective dose, species, age and immune status of the host. Probiotics are proposed as an attractive alternative possibility in the prevention against this pathogen infection. Previously we demonstrated that continuous Lactobacillus casei CRL 431 administration to BALB/c mice before and after challenge with Salmonella enterica serovar Typhimurium (S. Typhimurium) decreased the severity of Salmonella infection. The aim of the present work was to deep into the knowledge about how this probiotic bacterium exerts its effect, by assessing its impact on the expression and secretion of pro-inflammatory (TNFα, IFNγ) and anti-inflammatory (IL-10) cytokines in the inductor and effector sites of the gut immune response, and analyzing toll-like receptor (TLR2, TLR4, TLR5 and TLR9) expressions in both healthy and infected mice.ResultsProbiotic administration to healthy mice increased the expression of TLR2, TLR4 and TLR9 and improved the production and secretion of TNFα, IFNγ and IL-10 in the inductor sites of the gut immune response (Peyer's patches). Post infection, the continuous probiotic administration, before and after Salmonella challenge, protected the host by modulating the inflammatory response, mainly in the immune effector site of the gut, decreasing TNFα and increasing IFNγ, IL-6 and IL-10 production in the lamina propria of the small intestine.ConclusionsThe oral administration of L. casei CRL 431 induces variations in the cytokine profile and in the TLRs expression previous and also after the challenge with S. Typhimurium. These changes show some of the immune mechanisms implicated in the protective effect of this probiotic strain against S. Typhimurium, providing an alternative way to reduce the severity of the infection.

Lactobacillus rhamnosus GR-1 Ameliorates Escherichia coli-Induced Inflammation and Cell Damage via Attenuation of ASC-Independent NLRP3 Inflammasome Activation

“…Activation of TLR2 signaling triggered by L. rhamnosus is most likely mediated by peptidoglycans, lipoproteins, and lipoteichoic acids from Gram-positive bacteria. Certain Lactobacillus strains may exert anti-inflammatory effects via TLR2 activation (29,30). In addition, activation of TLR2 signaling was shown to induce neutrophil recruitment and restrict invasion of E. coli P4 into mammary gland epithelial cells in a murine mastitis model (31).…”

Genetically Engineered Immunomodulatory Streptococcus thermophilus Strains Producing Antioxidant Enzymes Exhibit Enhanced Anti-Inflammatory Activities

“…Commercial peripheral blood mononuclear cells (PBMC) from healthy donors were obtained from StemCell Technologies (Grenoble, France) and grown in RPMI 1640 medium (Sigma, St. Louis, MO, USA) with 1% L-glutamine and 10% heat-inactivated fetal bovine serum (FBS) in a humidified 10% CO 2 atmosphere at 37°C (32). Isolation of Peyer's patch mononuclear cells (PPMC) from healthy mice was performed as previously described (11).…”

Stimulation of Innate Immune Cells Induced by Probiotics: Participation of Toll-Like Receptors

“…Previous studies conducted in our laboratory showed that probiotic bacteria induced increases in the TLRs expression in the immune cells of lamina propria of the small intestine and in the Peyer´s patches, which seemed to suggest the involvement of these receptors, in the signaling pathways induced by probiotic microorganisms in the gut [8,19]. In vitro studies demonstrated that two Lactobacillus strains, L. rhamnosus GG and L. plantarum BFE 1685 increase the expression of TLR2 in intestinal epithelial cells line HT-29 [20].…”