Antimicrobial peptide MPX attenuates LPS-induced inflammatory response and blood-testis barrier dysfunction in Sertoli cells

Orchitis accounts for a high proportion of male animal reproductive disorders. Hence, it is urgent to identify drugs for the prevention and treatment of orchitis. Antimicrobial peptides (AMPs) are currently recognized as one of the most promising alternatives to antibiotics. However, the protective effects of AMPs on lipopolysaccharide (LPS)-induced orchitis have not been reported. In this study, we developed an LPS-induced orchitis model in which primary bovine Sertoli cells were used as model cells. MPX was indicated to effectively reduce the inflammatory response of Sertoli cells. MPX attenuated the gene expression of the proinflammatory cytokines TNF-α, IL-6 and IL-1β by suppressing the MAPK pathway, especially the phosphorylation of p38 and ERK. MPX also decreased the oxidative stress response caused by LPS and upregulated Occludin and Claudin-1 expression, thereby maintaining the integrity of the blood-testis barrier. Moreover, we found that MPX inhibited apoptosis in Sertoli cells. In a mouse model, we found that MPX significantly inhibited the disruptive effects of LPS, reducing seminiferous epithelium damage, vacuolations, hyperplasia, and apoptosis in spermatogenic cells and rescuing spermatogenesis. In addition, the expression of inflammatory factors such as IL-1β, IL-18, IL-6 and TNF-α was decreased after MPX treatment in the mouse testes. MPX had no effect on other organs in mice, indicating its safety. This study was undertaken to investigate how MPX regulates the inflammatory response in Sertoli cells and provide a reference for the clinical prevention and treatment of male animal orchitis.