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Background Bovine mastitis characterized by mammary gland inflammatory responses, is the most frequent and costly diseases in dairy cattle. Researchers have been seeking effective treatments for this disease, but still not very successful. Ras-related C3 botulinum toxin substrate 1 (Rac1) is implicated in various cellular functions, including apoptosis, ROS production and inflammatory responses, and presents an attractive therapeutic target for many diseases. However, the effects of Rac1 signaling on mastitis remain unclear. The aim of this study is to investigate the effects of Rac1 signaling on mastitis via inhibition by Rac1 specific inhibitor NSC23766 based on a murine model of lipoplysaccharide (LPS)-induced mastitis. Methods Murine mastitis model was established by perfusion of LPS, hematoxylin-eosin (H & E) staining was employed to explore the mechanisms in mouse model, qRT- PCR analysis, Western blotting analysis. Results The results revealed that NSC23766 significantly decreased the damage of mammary gland by LPS, reduced myeloperoxidase activities, and the productions of IL-1β, IL-6, TNF-α and MCP-1 gene expression in the mammary glands with LPS perfusion. Moreover, western blot analysis showed that NSC23766 inhibited the phosphoryation of p65, IκBα, ERK, and p38, and suppressed the expression of NLRP3. Conclusion These findings suggested that administration of NSC23766 prevented the development of mastitis by inhibiting NLRP3, mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathways. Accordingly, this study may provide research basis for the development of new drugs against mastitis, and NSC23766 might be a potential therapeutic drugs for mastitis.

Trichomonas vaginalis is responsible for the prevalence of trichomoniasis, which may be one of the most epidemic nonviral sexually transmitted pathogens. Extracellular traps (ET) are a unique form of innate immunity against infection; they bind to and kill microorganisms. However, the effect of T. vaginalis on ET release in the human monocytic cell line THP-1 remains unclear. In the present study, the morphology of ET derived from THP-1 in response to T. vaginalis was observed by scanning electron microscopy (SEM). The results demonstrated ET entangling T. vaginalis. Then, the colocalization of histone (H3) and myeloperoxidase (MPO) with DNA was observed via fluorescence confocal microscopy. Colocalization revealed the classic characteristics of DNA decorated with H3 and MPO. T. vaginalis significantly increased reactive oxygen species (ROS) and THP-1-derived ET. In addition, we measured the levels of lactic dehydrogenase (LDH) and the phosphorylation of the P38 and ERK1/2 MAPK signaling pathways. The results indicated that the formation of ET induced by T. vaginalis was related to phosphorylation of the P38 and ERK1/2 MAPK signaling pathways but not to LDH levels. These data confirmed the phenomenon of THP-1-derived ET being triggered by T. vaginalis in vitro; this process may play a pivotal role in innate immunity during defense against T. vaginalis infection.

Chlorogenic acid (CGA), one of the most abundant polyphenols in the diet, has been reported to have potent anti-inflammatory properties. However, the effect of CGA on lipopolysaccharide (LPS)-induced mice mastitis has not been investigated. The purpose of the present study was to elucidate whether CGA could ameliorate the inflammation response in LPS-induced mice mastitis and to clarify the possible mechanism. The mouse model of mastitis was induced by injection of LPS through the duct of mammary gland. CGA was administered intraperitoneally with the dose of 12.5, 25, and 50mg/kg respectively 1h before and 12h after induction of LPS. In this study, the effect of CGA on LPS-induced mice mastitis was assessed through histopathological examination, ELISA assay, and western blot analysis. The results showed that CGA significantly reduced TNF-α, IL-1β, and IL-6 production compared with LPS group. Besides, western blot analysis showed that CGA could inhibit the expression of TLR4 and the phosphorylation of NF-κB and IκB induced by LPS. These results suggested that anti-inflammatory effects of CGA against LPS-induced mastitis may be due to its ability to inhibit TLR4-mediated NF-κB signaling pathway. Therefore, CGA may be a potent therapeutic reagent for the prevention of the immunopathology encountered during Escherichia coli elicited mastitis.

Cepharanthine (CEP), a biscoclaurine alkaloid isolated from Stephania cepharantha Hayata, has been reported to have potent anti-inflammatory properties. However, the anti-inflammatory effects of CEP on a mouse model of lipopolysaccharide (LPS)-induced mastitis and its underlying molecular mechanisms remain to be elucidated. The purpose of the present study was to investigate the effects of CEP on LPS-induced mouse mastitis. The mouse model of mastitis was induced by inoculation of LPS through the canals of the mammary gland. CEP was administered intraperitoneally at 1 h before and 12 h after induction of LPS. The results show that CEP significantly attenuates the infiltration of neutrophils, suppresses myeloperoxidase activity, and reduces the levels of TNF-α, IL-1β, and IL-6 in LPS-induced mouse mastitis. Furthermore, CEP inhibited the phosphorylation of NF-κB p65 subunit and the degradation of its inhibitor IκBα. All the results suggest that CEP exerts potent anti-inflammatory effects on LPS-induced mouse mastitis. Accordingly, CEP might be a potential therapeutic agent for mastitis.