Eugenol alleviates transmissible gastroenteritis virus-induced intestinal epithelial injury by regulating NF-κB signaling pathway
Kang Wang, Daiwen Chen, Bing Yu, Jun He, Xiangbing Mao, Zhiqing Huang, Hui Yan, Aimin Wu, Yuheng Luo, Ping Zheng, Jie Yu, Junqiu Luo
Abstract
Increasing evidence supports the ability of eugenol to maintain intestinal barrier integrity and anti-inflammatory in vitro and in vivo ; however, whether eugenol alleviates virus-mediated intestinal barrier damage and inflammation remains a mystery. Transmissible gastroenteritis virus (TGEV), a coronavirus, is one of the main causative agents of diarrhea in piglets and significantly impacts the global swine industry. Here, we found that eugenol could alleviate TGEV-induced intestinal functional impairment and inflammatory responses in piglets. Our results indicated that eugenol improved feed efficiency in TGEV-infected piglets. Eugenol not only increased serum immunoglobulin concentration ( IgG ) but also significantly decreased serum inflammatory cytokine concentration ( TNF-α ) in TGEV-infected piglets. In addition, eugenol also significantly decreased the expression of NF-κB mRNA and the phosphorylation level of NF-κB P65 protein in the jejunum mucosa of TGEV-infected piglets. Eugenol increased villus height and the ratio of villus height to crypt depth in the jejunum and ileum, and decreased serum D-lactic acid levels. Importantly, eugenol increased tight junction protein ( ZO-1 ) and mRNA expression levels of nutrient transporter-related genes ( GluT-2 and CaT-1 ) in the jejunum mucosa of TGEV-infected piglets. Meanwhile, compared with TGEV-infected IPEC-J2 cells, treatment with eugenol reduced the cell cytopathic effect, attenuated the inflammatory response. Interestingly, eugenol did not increase the expression of ZO-1 and Occludin in IPEC-J2 cells. However, western blot and immunofluorescence results showed that eugenol restored TGEV-induced down-regulation of ZO-1 and Occludin, while BAY11-7082 (The NF-κB specific inhibitor) enhanced the regulatory ability of eugenol. Our findings demonstrated that eugenol attenuated TGEV-induced intestinal injury by increasing the expression of ZO-1 and Occludin , which may be related to the inhibition of NF-κB signaling pathway. Eugenol may offer some therapeutic opportunities for coronavirus-related diseases.