Investigating the impact of CX3CR1+ macrophage depletion on gut barrier integrity.

Abstract

The intestinal barrier regulates nutrient absorption and prevents microbial translocation. CX3CR1⁺ macrophages play a critical role in maintaining epithelial integrity and immune homeostasis. This study examines the impact of CX3CR1⁺ macrophage depletion on intestinal epithelial structure, immune composition, and permeability using the CX3CR1-Cre;iDTR model. Flow cytometry revealed Ly6C⁺ monocyte expansion in the small intestine, reduced T cells, increased B220⁺ B cells, and fewer antigen-presenting cells in the colon. ELISA showed elevated serum IgG, suggesting systemic immune activation upon CX3CR1⁺ cell depletion. Histological analysis demonstrated epithelial disruption, goblet cell loss, and diffuse architectural alterations. Tight junction gene expression analysis by RT-qPCR indicated barrier impairment, with occludin, claudin-3, and claudin-4 downregulated in the small intestine, while claudin-2 was upregulated in the colon. These findings underscore CX3CR1⁺ macrophages as essential regulators of mucosal immunity and barrier function. Targeting the CX3CL1/CX3CR1 axis may offer a therapeutic strategy for restoring gut integrity in inflammatory disorders.