Selenomethionine Inhibits NF-κB-mediated Inflammatory Responses of Bovine Mammary Epithelial Cells Caused by Klebsiella pneumoniae by Increasing Autophagic Flux

• Published in: Biological trace element research 2024-04, Vol.202 (4), p.1568-1581
• Main Authors: Xu, Siyan, Miao, Yixue, Dong, Junsheng, Cui, Luying, Liu, Kangjun, Li, Jianji, Meng, Xia, Zhu, Guoqiang, Wang, Heng
• Format: Article
• Language: English
• Subjects: Autophagy; Biochemistry; Biomedical and Life Sciences; Biotechnology; Cattle; Chloroquine; Dairy cattle; Epithelial cells; Epithelium; Fluctuations; Homeostasis; Inflammation; Klebsiella; Klebsiella pneumoniae; Life Sciences; Lymphocytes; Lymphocytes T; Mammary gland; Mastitis; NF-κB protein; Nutrition; Oncology; Pathogens; Selenium; Selenomethionine; Vesicles
• ISSN: 0163-4984; 1559-0720
• DOI: 10.1007/s12011-023-03757-2

Klebsiella pneumoniae ( K. pneumoniae ) is one of the major pathogens causing bovine clinical mastitis. Autophagy maintains cellular homeostasis and resists excessive inflammation in eukaryotic organisms. Selenomethionine (Se-Met) is commonly used as a source of selenium supplementation for dairy cows. This study aimed to investigate the effects of Se-Met on inflammatory responses mediated by nuclear factor-kappa B (NF-κB) through autophagy. We infected bovine mammary epithelial cell line (MAC-T) with K. pneumoniae and examined the expression of autophagy-related proteins and changes in autophagic vesicles, LC3 puncta, and autophagic flux at various intervals. The results showed that K. pneumoniae activated the early-stage autophagy of MAC-T cells. The levels of LC3-II, Beclin1, and ATG5, as well as the number of LC3 puncta and autophagic vesicles, increased after 2 h post-treatment. However, the late-stage autophagic flux was blocked. Furthermore, the effect of autophagy on NF-κB-mediated inflammation was investigated with different autophagy levels. The findings showed that enhanced autophagy inhibited the K. pneumoniae -induced inflammatory responses of MAC-T cells. The opposite results were found with the inhibition of autophagy. Finally, we examined the effect of Se-Met on NF-κB-mediated inflammation based on autophagy. The results indicated that Se-Met alleviated K. pneumoniae -induced autophagic flux blockage, inhibited NF-κB-mediated inflammation, and decreased the adhesion of K. pneumoniae to MAC-T cells. The inhibitory effect of Se-Met on NF-κB-mediated inflammation could be partially blocked by the autophagy inhibitor chloroquine (CQ). Overall, Se-Met attenuated K. pneumoniae -induced NF-κB-mediated inflammatory responses by enhancing autophagic flux.