Enhancing intestinal epithelial microtubule stability could alleviate IBD symptoms

Background: Inflammatory bowel disease (IBD) is characterized by epithelial barrier dysfunction, where in the Cytoskeleton, especially actin microfilaments and intermediate filaments, has been extensively investigated for its critical role in maintaining the structural integrity of the epithelial barrier. However, the specific contribution of microtubules to this process remains unknown.

Methods: In this study, we analyzed the expression of acetylated α-tubulin (Ac-α-tubulin), a marker of stable microtubule structures, in colonic tissues from IBD patients and healthy controls using immunofluorescence. We also employed dextran sulfate sodium (DSS) to induce colitis in murine models and stimulated Caco-2 cells with tumor necrosis factor-alpha (Tnfα) to elucidate the subsequent alterations in microtubule dynamics. We subsequently evaluated the impact of microtubule-associated protein kinase 2 (MARK2) deficiency on microtubule dynamics, epithelial permeability, and inflammation. This was accomplished using both stable MARK2 knockdown Caco-2 cell lines and intestinal epithelial-specific MARK2 conditional knockout (MARK2^vil1) mice. Additionally, we explored whether treatment with the microtubule stabilizer paclitaxel (PTX) and the SIRT2 selected inhibitor AGK2 could reverse these phenotypic changes.

Results: Our findings revealed a significant reduction in Ac-α-tubulin expression in both IBD patient tissues and the DSS-induced colitis model. Treatment with PTX significantly enhanced Ac-α-tubulin levels and mitigated colitis symptoms in DSS-induced mice. Furthermore, MARK2 knockdown decreased Ac-α-tubulin expression and increased paracellular permeability, which could be reversed by AGK2 or PTX treatment.

Conclusion: This study provides new insights into the pathogenesis of IBD by elucidating the role of microtubules in epithelial barrier disruption. Our findings propose microtubule-modulating therapeutics as a potential novel treatment strategy for IBD, highlighting the importance of stabilizing microtubules to restore epithelial integrity and reduce inflammation.

AGK2; Acetylated α-tubulin (Ac-α-tubulin); Epithelial barrier dysfunction; Inflammatory bowel disease (IBD); Microtubule-associated protein kinase 2 (MARK2); Microtubules; Paclitaxel (PTX).