Regulation of interleukin-1 beta gene expression and its function of defense mechanism in rumen epithelial cells from pre- and postweaning calves

초록

Objective This study aimed to elucidate interleukin-1 beta (IL-1 beta) gene expression regulation and its function of defense mechanism in rumen epithelial cells of calves. Methods Rumen tissues from six Holstein male calves were sampled at pre- (5 weeks of age, n = 3) and post-weaning (9 weeks of age, n = 3). IL-1 beta localization was analyzed using immunohistochemistry (IHC). Primary bovine rumen epithelial cells (BRECs) were treated with short-chain fatty acids (SCFAs), beta-hydroxybutyrate, lactic acid, lipopolysaccharide (LPS), and flagellin, and IL-1 beta gene expression was analyzed by quantitative real-time polymerase chain reaction. Additionally, bovine IL-1 beta-treated BRECs were assessed for cell proliferation, tight junction (TJ) protein expression, and chemokine mRNA expression. Results IHC revealed IL-1 beta expression across all rumen epithelial layers. SCFAs, LPS, and flagellin significantly increased IL-1 beta mRNA expression (p<0.05). Regarding the gene expression of rumen TJ proteins, CLDN4 and OCLN in suckling and weaned calves, as well as ZO-1 in weaned calves, showed significant decreases (p<0.05), while CLDN1 in weaned calves showed a significant increase (p<0.05) in IL-1 beta-treated BRECs. Regarding the gene expression of chemokines, the CCL2 expression significantly decreased (p<0.05), while the CCL5 expression significantly increased (p<0.05) in both suckling and weaned IL-1 beta treated BRECs. IL-1 beta treatment enhanced cell proliferation (p<0.05). Conclusion These results suggest that IL-1 beta induction by SCFAs, LPS, and flagellin, which increase in the rumen due to environmental changes, promotes cell proliferation in damaged rumen epithelium and contributes to its defense mechanism by upregulating CCL5 expression.

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