GRHL2 contributes to the maintenance of intestinal epithelial barrier integrity during LPS-induced injury

Sepsis-induced intestinal epithelial barrier dysfunction contributes to gastrointestinal injury during critical illness, yet the molecular mechanisms underlying barrier disruption remain incompletely understood. This study investigated the potential involvement of Grainyhead-like 2 (GRHL2) in lipopolysaccharide (LPS)-induced intestinal epithelial barrier injury.

LPS-induced intestinal barrier injury was evaluated using Caco-2 monolayers and a mouse endotoxemia model. Barrier integrity was assessed by transepithelial electrical resistance (TEER), immunofluorescence, histological analysis, serum cytokine measurement, and FITC-dextran permeability assays. Transcriptomic analysis was performed to identify biological processes associated with LPS-induced intestinal injury. GRHL2 expression was evaluated by qRT-PCR, immunohistochemistry, and Western blotting. Gain- and loss-of-function experiments were performed using lentiviral-mediated GRHL2 overexpression and knockdown in vivo.

LPS exposure impaired epithelial barrier integrity, as evidenced by reduced TEER values, disrupted Occludin distribution, increased serum TNF-α and IL-6 concentrations, histological injury, and enhanced intestinal permeability. 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 expression was significantly reduced in LPS-treated intestinal tissues together with decreased expression of several epithelial junction-associated molecules, including E-cadherin, Claudin-3, Claudin-4, and Occludin. Functional modulation demonstrated that GRHL2 knockdown aggravated intestinal injury and permeability, whereas GRHL2 overexpression attenuated barrier dysfunction and was accompanied by increased expression of multiple epithelial junction-associated molecules.

These findings demonstrate that GRHL2 contributes to the maintenance of intestinal epithelial barrier integrity during LPS-induced injury. The observed association between GRHL2 downregulation and impaired expression of epithelial junction-associated molecules suggests that GRHL2 may participate in the epithelial response to inflammatory injury. Further studies are required to clarify the molecular mechanisms underlying GRHL2 regulation and its role in intestinal barrier homeostasis.