Objective:

To investigate the involvement of Grainyhead-like 2 (GRHL2) in lipopolysaccharide (LPS)-induced intestinal epithelial barrier injury.

Approach:

• In vitro and in vivo models: Caco-2 monolayers and a mouse endotoxemia model were used to evaluate LPS-induced intestinal barrier injury.
• Assessment methods: Barrier integrity was assessed using transepithelial electrical resistance (TEER), immunofluorescence, histological analysis, serum cytokine measurement, and FITC-dextran permeability assays.
• GRHL2 expression analysis: GRHL2 expression was evaluated by qRT-PCR, immunohistochemistry, and Western blotting.
• Functional modulation: Gain- and loss-of-function experiments were performed using lentiviral-mediated GRHL2 overexpression and knockdown.

Key Findings:

• LPS exposure impaired epithelial barrier integrity, reducing TEER values and disrupting Occludin distribution.
• Increased serum TNF-α and IL-6 concentrations were observed alongside histological injury and enhanced intestinal permeability.
• GRHL2 expression was significantly reduced in LPS-treated intestinal tissues, correlating with decreased expression of epithelial junction-associated molecules.
• Transcriptomic analysis revealed marked transcriptional alterations following LPS exposure, with enrichment of biological processes related to inflammatory responses, cell–cell adhesion, epithelial development, and extracellular matrix organization.
• GRHL2 knockdown aggravated intestinal injury and permeability, while GRHL2 overexpression attenuated barrier dysfunction and was accompanied by increased expression of multiple epithelial junction-associated molecules.

Interpretation:

GRHL2 contributes to maintaining intestinal epithelial barrier integrity during LPS-induced injury.

Limitations:

• Further studies are required to clarify the molecular mechanisms underlying GRHL2 regulation.
• The study primarily focuses on in vitro and animal models, which may not fully replicate human conditions.

Conclusion:

GRHL2 plays a significant role in the epithelial response to inflammatory injury, suggesting its potential importance in intestinal barrier homeostasis.