Alteration of Colonic Mucosal Permeability during Antibiotic-Induced Dysbiosis

Area of Science:

• Gastroenterology
• Microbiology
• Immunology

Background:

• Gut dysbiosis, an imbalance in microbial communities, is implicated in mucosal barrier dysfunction.
• The precise mechanisms by which dysbiosis affects colonic mucosal integrity remain incompletely understood.

Purpose of the Study:

• To investigate the impact of antibiotic-induced dysbiosis on colonic mucosal permeability and tight junction (TJ) molecule expression in mice.
• To explore the role of specific cytokines, such as TNF-α and IFN-γ, in mediating these changes.

Main Methods:

• Antibiotic treatment (vancomycin or polymyxin B) in mice to induce dysbiosis.
• Assessment of gut microbiota diversity using 16S rRNA gene sequencing.
• Measurement of colonic mucosal permeability using Ussing chamber assays.
• Analysis of TJ protein and cytokine expression via real-time RT-PCR, Western blotting, and immunohistochemistry.
• In vitro studies using Caco2 cells to assess the effect of cytokines on transepithelial electrical resistance (TEER).

Main Results:

• Antibiotic administration significantly reduced gut microbial diversity.
• Colonic mucosal permeability was markedly increased in antibiotic-treated mice.
• Expression of claudin 4, a key TJ protein, was decreased in the colonic mucosa.
• Colonic expression of pro-inflammatory cytokines TNF-α and IFN-γ was significantly elevated.
• In vitro, TNF-α and IFN-γ stimulation dose-dependently reduced TEER in Caco2 cells, indicating barrier disruption.

Conclusions:

• Antibiotic-induced dysbiosis enhances colonic tissue permeability.
• This enhancement is associated with reduced claudin 4 expression and increased TNF-α and/or IFN-γ levels.
• These findings elucidate a mechanism by which gut dysbiosis compromises mucosal barrier function.