Critical role of RIG-I-like receptors in inflammation in chronic obstructive pulmonary disease

Abstract

Introduction: Viral infection is a significant cause of chronic obstructive pulmonary disease (COPD) and acute exacerbation of COPD. Retinoic acid inducible gene I (RIG-I)-like receptors (RLRs), including RIG-I and melanoma differentiation associated gene 5 (MDA-5), are important pattern recognition receptors for viral elimination.

Objective: The study aims to investigate the role of RIG-I and MDA-5 in COPD pathogenesis.

Methods: We examined the expression of RIG-I and MDA-5 by immunohistochemistry, real-time PCR and Western blots in COPD patients and control subjects.

Results: Our results showed that MDA-5 expression was upregulated in lung tissues and peripheral blood mononuclear cells of COPD patients and there was a negative correlation between MDA-5 mRNA levels and forced expiratory volume in 1 s %pred. COPD patients had higher interleukin (IL)-1 and IL-8 mRNA expression levels, and these inflammatory cytokines positively correlate with MDA-5 levels. However, there was no difference in the expression of RIG-I between COPD patients and control subjects.

Conclusion: Our results suggested that MDA-5, but not RIG-I, may play a critical role in airway inflammation in COPD.

Keywords: MDA-5; RIG-I; RIG-I-like receptors; airway inflammation; nic obstructive pulmonary disease.