Berberine improves intestinal epithelial tight junctions by upregulating A20 expression in IBS-D mice

Area of Science:

• Gastroenterology
• Molecular Biology
• Pharmacology

Background:

• Diarrhea-predominant irritable bowel syndrome (IBS-D) is characterized by impaired intestinal epithelial barrier function.
• The tumor necrosis factor-alpha (TNF-α)-nuclear factor-kappa B (NF-κB)-myosin light chain kinase (MLCK) pathway is implicated in IBS-D pathogenesis.
• A20, a key negative regulator of NF-κB signaling, plays a role in maintaining intestinal homeostasis.

Purpose of the Study:

• To investigate the therapeutic effects of berberine on IBS-D.
• To elucidate the role of A20 in berberine's mechanism of action.
• To examine the impact of berberine on the TNF-α-NF-κB-MLCK pathway and intestinal tight junctions in a mouse model of IBS-D.

Main Methods:

• An experimental model of IBS-D was established in C57BL/6 wild-type (WT) and A20 intestinal epithelial cell-specific knockout (IEC-KO) mice.
• Mice were treated with berberine, rifaximin, or vehicle control.
• Intestinal tissue was analyzed for histological changes, protein expression (A20, TNF-α, NF-κB p65, MLCK, tight junction proteins), and pathway activation.

Main Results:

• Berberine treatment improved intestinal epithelial integrity in WT mice more significantly than in A20 IEC-KO mice.
• Berberine upregulated A20 expression and downregulated TNF-α, NF-κB p65, MLCK, and downstream signaling molecules in WT mice.
• Berberine increased the expression of tight junction proteins (occludin, claudin-1, ZO-1, F-actin) in WT mice, with a blunted effect in A20 IEC-KO mice.

Conclusions:

• Berberine exerts protective effects in a mouse model of IBS-D by upregulating A20 expression.
• Berberine inhibits the abnormal activation of the TNF-α-NF-κB-MLCK pathway.
• Berberine repairs intestinal epithelial tight junctions and ameliorates IBS-D-induced intestinal barrier damage.