Corticosteroid regulates epithelial occludin expression in nasal polyps through a MKP-1-dependent pathway

Area of Science:

• Immunology
• Otolaryngology
• Molecular Biology

Background:

• Chronic rhinosinusitis with nasal polyps (CRSwNP) is a complex inflammatory condition.
• Epithelial barrier dysfunction may contribute to CRSwNP pathogenesis.
• Occludin is a key protein in maintaining epithelial barrier integrity.

Purpose of the Study:

• To investigate the effect of corticosteroids on occludin expression in CRSwNP.
• To elucidate the molecular mechanisms underlying corticosteroid-induced changes in occludin.
• To evaluate the role of MKP-1 in corticosteroid-mediated regulation of occludin.

Main Methods:

• Twenty CRSwNP patients received prednisone treatment.
• Occludin expression in polyp tissues was analyzed pre- and post-treatment using immunohistochemistry and qRT-PCR.
• Occludin and MKP-1 expression were assessed in cultured polyp-derived epithelial cells (PECs) and bronchial epithelial cells (BECs) with corticosteroid and/or MKP-1 siRNA treatment via Western blot.

Main Results:

• Prednisone significantly upregulated occludin mRNA and protein in CRSwNP polyp tissues.
• Corticosteroids increased MKP-1 and occludin expression in cultured PECs.
• MKP-1 siRNA significantly decreased occludin expression in cultured BECs, indicating a MKP-1 dependent mechanism.

Conclusions:

• Corticosteroids enhance occludin expression in nasal polyps.
• The mechanism involves the MKP-1 signaling pathway.
• These findings suggest a potential therapeutic target for improving epithelial barrier function in CRSwNP.