Alterations to the vaginal microbiota and their correlation with serum pro-inflammatory cytokines in post-weaning sows with endometritis

Abstract

Endometritis is a prevalent disease in sows that strongly reduces reproductive performance. Its causes are complex and multifaceted, making disease management challenging without targeted measures. To provide a scientific basis for developing targeted disease management strategies, we examined vaginal microbiota diversity and its correlation with serum pro-inflammatory cytokine levels in sows with endometritis and the main pathogenic bacterial species contributing to endometritis. Fourteen post-weaning sows selected at a pig farm in Beijing, China, were randomly divided into healthy (C) and endometritis (E) groups. Levels of cytokines including interleukin-1α (IL-1α), IL-1β, IL-6, IL-8, and tumor necrosis factor-α (TNF-α) were quantified by enzyme-linked immunosorbent assays. Vaginal microbiota species were identified using 16S rDNA sequencing. Concentrations of IL-1α and IL-6 in serum and vaginal microbial diversity were significantly increased in group E versus group C. The relative abundance of Firmicutes exhibited a marked increase in group E, whereas that of Fusobacteriota was significantly decreased. The composition and relative abundance of dominant bacterial genera differed between the two groups, and the dominant genera in group E were Clostridium_sensu_stricto_1, UCG-005, UCG-002, Terrisporobacter, and Christensenellaceae_R-7_group. IL-6 was significantly positively correlated with Clostridium_sensu_stricto_1 and Terrisporobacter in group E. These results suggest that vaginal microbiota abundance and diversity and serum pro-inflammatory cytokine levels are increased in sows with endometritis, and the latter are closely associated with vaginal microbiota abundance and composition. This study provides a foundation for investigating the pathogenesis of endometritis in sows and a theoretical basis for disease prevention and treatment.