Interleukin-17A plays a pivotal role in polymicrobial sepsis according to studies using IL-17A knockout mice.

Background: Interleukin (IL)-17A is a proinflammatory cytokine and plays an important role in neutrophil recruitment. We investigate the role of IL-17A in a mouse polymicrobial sepsis model.

Materials And Methods: IL-17A knockout mice (KO) and wild-type (WT) mice were subjected the cecal ligation and puncture (CLP). Survival was assessed for the following 7 d after the CLP operation, and histopathologic findings were evaluated 12 h after CLP. Bacterial outgrowth in blood was assessed by blood culture 12 h after CLP. After CLP, expression of inflammatory mediators in serum was assessed by enzyme-linked immunosorbent assay (ELISA). Furthermore, expression of FOXP3 and IL-17A in the spleen was assessed by immunohistochemical staining and flow cytometry.

Results: Mortality was increased in KO mice compared with WT mice after CLP. Furthermore, bacterial outgrowth in blood and serum high mobility group box 1 (HMGB1) levels were also significantly greater in KO mice than WT mice. The expression of FOXP3 in the spleen was significantly greater in KO mice than WT mice.

Conclusion: IL-17A play pivotal role in host defense during septic peritonitis.