Carbocisteine inhibits the expression of Muc5b in COPD mouse model

Abstract

Background

Cigarette smoke (CS) results in chronic mucus hypersecretion and airway inflammation, contributing to COPD pathogenesis. Mucin 5B (MUC5B) and mucin 5 AC (MUC5AC) are major mucins implicated in COPD pathogenesis. Carbocisteine can reduce mucus viscosity and elasticity. Although carbocisteine decreased human elastase-induced MUC5AC expression in vitro and reduced MUC5AC expression that alleviated bacteria adhesion and improved mucus clearance in vivo, the roles of carbocisteine in inducing MUC5B expression in COPD remain unclear.

Methods

To investigate the Muc5b/Muc5ac ratio and the gene and protein levels of Muc5b in COPD and carbocisteine intervention models. C57B6J mice were used to develop COPD model by instilling intratracheally with lipopolysaccharide on days 1 and 14 and were exposed to CS for 2 hr twice a day for 12 weeks. Low and high doses of carbocisteine 112.5 and 225 mg/kg/d, respectively, given by gavage administration were applied for the treatment in COPD models for the same duration, and carboxymethylcellulose was used as control. Carbocisteine significantly attenuated inflammation in bronchoalveolar lavage fluid and pulmonary tissue, improved pulmonary function and protected against emphysema.

Results

High-dose carbocisteine significantly decreased the overproduction of Muc5b (P<0.01) and Muc5ac (P<0.001), and restored Muc5b/Muc5ac ratio in COPD model group (P<0.001). Moreover, the Muc5b/Muc5ac ratio negatively correlated with pro-inflammatory cytokines such as IL-6 and keratinocyte-derived cytokine, mean linear intercept, functional residual capacity and airway resistance, but positively correlated with dynamic compliance.

Conclusions

These findings suggest that carbocisteine attenuated Muc5b and Muc5ac secretion and restored Muc5b protein levels, which may improve mucus clearance in COPD.

Keywords:

• COPD
• cigarette smoke
• Muc5b
• Muc5ac
• carbocisteine

Acknowledgment

This study was supported by grants from the National Key R&D Program of China (No.2018YFC1311900), the National Natural Science Foundation of China (No.81470234), the Guangdong provincial project for great new drug research and development (No. 2012A080201003) and the National Key  Technology R&D Program (No.2012BAI05B01, 2013BAI09B09).

Author contributions

All authors contributed to data analysis, drafting or revising the article, gave final approval of the version to be published, and agree to be accountable for all aspects of the work.

Disclosure

The abstract has been submitted to the 22nd Congress of the Asian Pacific Society of Respirology, International Convention Centre, Sydney, Australia, 23–26 November 2017 and has been published in Respirology, Vol 22 Issue S3. The authors report no other conflicts of interest in this work.

Abbreviations

CS, cigarette smoke; BALF, bronchoalveolar lavage fluid; KC, keratinocyte-derived cytokine; MLI, mean linear intercept; CMH, chronic mucus hypersecretion; LPS, Lipopolysaccharide; FRC, The functional residual capacity; RI, airway resistance; Cdyn, dynamic compliance.