Consumption of L. casei prevents joint inflammation triggered during Salmonella enterocolitis

NOTO LLANA M, GARAVELLO G, SARNACKI SH, GIACOMODONATO MN, CERQUETTI MC.

Boston

Conferencia; 4th ASM Conference on Salmonella: The Bacterium, the Host and the Environment.; 2013

American Society for Microbiology

Reactive arthritis (ReA) is the development of sterile joint inflammation as a sequel to a remote infection, often in the gut. We have previously shown that oral infection with a low dose of S. Enteritidis of streptomycin-pretreated mice renders a suitable model for studying ReA. Here we showed that consumption of L. casei prior to infection abolishes intestinal and joint inflammation triggered by Salmonella enterocolitis. BALB/c mice were inoculated orally with 20 mg of streptomycin and 24 h later they received 10E3 CFU of a virulent strain of S. Enteritidis by the same route. To test the effect of probiotics mice were fed with commercially-available Lactobacillus casei, ad libitum, for 7 days before Salmonella infection. At different time post-infection animals were sacrificed and samples were obtained. Salmonella was recovered from Peyer´s patches up to day 5 and from spleen up to day 14 in infected mice without probiotic treatment. Mice receiving L. casei were less colonized with Salmonella, and for a shorter period. In line with gut histological changes, infected mice presented synovitis in the knee joints with elevated levels of local TNF-alpha. Interestingly, L. casei consumption prevented Salmonella-induced synovitis. IL-23, IL-1beta, IL-6, IL-17 and TNF-alpha expression was measured by qPCR in cecum, and in mesenteric, popliteal and inguinal lymph nodes. Mice fed with the probiotic showed significantly diminished expression of all cytokines tested compared to infected animals not receiving L. casei. Interestingly, intestinal Salmonella-induced IL-17 expression was dramatically reduced in mice fed L. casei prior to infection (2.4 + 0.9 a.u.) compared to infected mice not receiving probiotics (24 + 4 a.u.). We showed earlier that neutralization of IL-17 in mice suffering from Salmonella enterocolitis prevented synovitis. Altogether our results show that consumption of L. casei prior to Salmonella enterocolitis abrogates intestinal and joint inflammation. A possible explanation for this beneficial effect is that the probiotic prevents the expression of cytokines needed for differentiation of IL-17-producing cells known to be involved in the generation of reactive arthritis such as Th17 and gamma-delta T cells.