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

## TL;DR

This study explores how interleukin-1 beta (IL-1β) helps protect the rumen lining in calves during and after weaning.

## Contribution

The study reveals how IL-1β gene expression is regulated and contributes to defense mechanisms in calf rumen cells.

## Key findings

- IL-1β expression increases in response to SCFAs, LPS, and flagellin in rumen epithelial cells.
- IL-1β treatment enhances cell proliferation and alters tight junction and chemokine gene expression.
- CCL5 expression increases, suggesting a role in defense mechanisms in damaged rumen epithelium.

## Abstract

This study aimed to elucidate interleukin-1 beta (IL-1β) gene expression regulation and its function of defense mechanism in rumen epithelial cells of calves.

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-1β 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-1β gene expression was analyzed by quantitative real-time polymerase chain reaction. Additionally, bovine IL-1β-treated BRECs were assessed for cell proliferation, tight junction (TJ) protein expression, and chemokine mRNA expression.

IHC revealed IL-1β expression across all rumen epithelial layers. SCFAs, LPS, and flagellin significantly increased IL-1β 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-1β-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-1β treated BRECs. IL-1β treatment enhanced cell proliferation (p<0.05).

These results suggest that IL-1β 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.