Effect of Propionate on Citrobacter rodentium Infection in Mice by Regulating NleH Expression

Propionate is one of the main short chain fatty acids in the gut. Previously, we found that propionate significantly down-regulated the expression of NleH. NleH is a virulence effector secreted by Citrobacter rodentium (C. rodentium, C.r.) and is essential for its intestinal colonisation and infection. Therefore, this study intends to explore the effect and mechanism of propionate on C.r. infection by regulating the expression of NleH. Wild-type C.r. and its NleH mutant (C.r.^△NleH), E.coli and its NleH1 mutant (E.coli^△NleH1) were co-cultured with propionate separately, changes in strain growth and invasion adhesion were detected. Meanwhile, C57BL/6J mice were infected with C.r. and C.r.^△NleH to establish animal model, and propionate intervention was given. Through detecting the invasive and infectious ability of strains in mice and the changes related to colon inflammation, to analyse the effect of propionate on C.r. infection by regulating NleH expression. The results showed that propionate can reduce the adhesion of C.r. and intestinal damage by down-regulating NleH expression, meanwhile changes of microbial functional metabolism enhance the resistance to C.r. infection in mice.