SRA

Acute gastrointestinal infection with intracellular pathogens like Salmonella Typhimurium triggers the release of the proinflammatory cytokine interleukin 1ß (IL-1ß). However, the role of IL-1ß in intestinal defense against Salmonella remains unclear. Here, we show that IL-1b production is detrimental during Salmonella infection. Mice lacking IL-1b (IL-1b -/-) failed to recruit neutrophils to the gut during infection, which reduced tissue damage and prevented depletion of short-chain fatty acid-producing commensals. Changes in epithelial cell metabolism that typically support pathogen expansion, such as switching energy production from fatty acid oxidation to fermentation, were absent in infected IL-1b -/- mice which inhibited Salmonella expansion. Additionally, we found that IL-1b induces expression of complement anaphylatoxins and suppresses the complement-inactivator Carboxypeptidase N (CPN1). Disrupting this process via IL-1b loss prevented mortality in Salmonella-infected IL-1b -/- mice. Finally, we found that IL-1b expression correlates with expression of the complement receptor in patients suffering from sepsis, but not uninfected patients and healthy individuals. Thus, Salmonella exploits IL-1b signaling to outcompete commensal microbes and establish gut colonization. Moreover, our findings identify the intersection of IL-1b signaling and the complement system as key host factors involved in controlling mortality during invasive Salmonellosis. Overall design: WT and IL-1b-/- C57BL/6 mice were orally infected with 10^7 CFU of Salmonella typhimurium SL1334. Feces were collected 4 days post-infection and DNA was extracted.