NLRP3 inflammasome is involved in testicular inflammation induced by lipopolysaccharide in mice

Problem Systemic inflammation induced by infection, which is associated with testicular inflammation, predisposes males to subfertility. Recently, the nucleotide‐binding oligomerization domain, leucine‐rich repeat‐, and pyrin domain‐containing 3 (NLRP3) inflammasome was identified as a key mediator of inflammation, and excessive activation of the NLRP3 inflammasome was shown to contribute to the pathogenesis of a wide variety of diseases. However, the mechanisms underlying infectious inflammation in the testis remain unclear. We investigated the effect of lipopolysaccharide (LPS)‐induced systemic inflammation on the role of the NLRP3 inflammasome in murine testes. Method of study We performed in vivo and in vitro studies using an LPS‐induced model of NLRP3 inflammasome activation and testicular inflammation. Results Intraperitoneal administration of LPS significantly impaired sperm motility in the epididymis of wild type (WT) and NLRP3‐knockout (KO) mice. LPS administration stimulated interleukin (IL)‐1β production and secretion in the testes of WT mice, and these adverse effects were improved in the testes of NLRP3‐KO mice. LPS administration also stimulated neutrophil infiltration as well as its chemoattractant C‐C motif chemokine ligand 2 (CCL2) in WT testes, which were suppressed in NLRP3‐KO testes. In in vitro cell culture, treatment with LPS and NLRP3 inflammasome activation significantly induced IL‐1β and CCL2 secretion from WT but not NLRP3‐KO testicular cells. Conclusions Taken together, our results suggest that testicular cells have the potential to secrete IL‐1β and CCL2 in an NLRP3 inflammasome‐dependent manner and that these cytokines from the testis may further exacerbate testicular function, resulting in subfertility during infectious diseases.