Aryl hydrocarbon receptor protects against viridans streptococci infection by activation of immune system through IL-17RA signaling

Abstract

The majority of bacterial infections during neutropenia following high-dose chemotherapy or stem cell transplantation are caused by coagulase-negative staphylococci, a large number are due to viridans streptococci. Despite considerable progress in the understanding of the AhR-mediated regulation of immune responses, the role of AhR in bacterial infections has not been clearly demonstrated. In the study presented here, we sought to determine whether the aryl hydrocarbon receptor (AhR) would protect mice from infection with viridans streptococci. AhR enhances the inflammatory response to viridans streptococci stimuli. Specifically, neutrophil numbers and levels of inflammatory cytokines are often increased in mice treated with viridans streptococci. Furthermore, AhR activation through the IL-17RA is required for protection against viridans streptococcal infection. Taken together, we concluded that AhR plays an important role in optimal innate immunoprotection against microbial infection through the down-regulation of immune response.