Inhibition of Neutrophil Extracellular Traps Formation by Cl-Amidine Alleviates Lipopolysaccharide-Induced Endometritis and Uterine Tissue Damage

SIMPLE SUMMARY: The progression of several inflammatory diseases, including endometritis, has been proven to be enhanced by the process of neutrophil extracellular traps (NETs) formation in pathogenesis. Therefore, averting the formation of NETs could be an effective method to combat endometritis. Cl-amidine has been reported to treat certain inflammatory diseases, but its therapeutic role in combating endometritis remains an enigma as it may likely attenuate NETs formation. Hence, we investigate the potential of NETs formation in the pathogenesis of endometritis using rats and the probable therapeutic indices of Cl-amidine against endometritis. It was revealed that LPS induced endometritis in rats, and the formation of NETs was detected in the rats’ inflamed uterine tissues. The treatment with Cl-amidine showed the regression of LPS-induced endometritis and protection against uterine tissue damage. Cl-amidine effectively reduced the expression of specific proteins that could enhance the formation of NETs, thereby attenuating the inflammatory response to LPS-induced endometritis in rats. Our research showed that Cl-amidine possesses potentially therapeutic properties against endometritis. ABSTRACT: Endometritis is a common disease that affects the production in dairy cows and leads to severe losses in the dairy industry. Neutrophil extracellular traps (NETs) formation promotes pathogenic invasions of the lumen of the tissue, leading to inflammatory diseases such as mastitis, pancreatitis, and septic infection. However, research that could show the relationship between NETs and endometritis is scarce. Cl-amidine has been shown to ameliorate the disease squealing and clinical manifestation in various disease models. In this study, we investigated the role of NETs in LPS-triggered endometritis in rats and evaluated the therapeutic efficiency of Cl-amidine. An LPS-induced endometritis model in rats was established and found that the formation of NETs can be detected in the rat’s uterine tissues in vivo. In addition, Cl-amidine treatment can inhibit NETs construction in LPS-induced endometritis in rats. Myeloperoxidase (MPO) activity assay indicated that Cl-amidine treatment remarkably alleviated the inflammatory cell infiltrations and attenuated the damage to the uterine tissue. The Western blot results indicated that Cl-amidine decreased the expression of citrullinated Histone H3 (Cit-H3) and high-mobility group box 1 protein (HMGB1) protein in LPS-induced rat endometritis. The ELISA test indicated that Cl-amidine treatment significantly inhibited the expression of the pro-inflammatory cytokines IL-1β, IL-6, and TNF-α. The NETs were determined by Quant-iT(TM)PicoGreen dsDNA kit(®), which indicated that Cl-amidine significantly inhibited the NETs in rat serum. All results showed that Cl-amidine effectively reduced the expression of Cit-H3 and HMGB1 proteins by inhibiting the formation of NETs, thereby attenuating the inflammatory response to LPS-induced endometritis in rats. Hence, Cl-amidine could be a potential candidate for the treatment of endometritis.