Circulating Complement C1q as a Novel Biomarker is Associated with the Occurrence and Development of COPD

Abstract

Purpose

Increasing evidence has shown that the immune response interacts with the chronic inflammatory response and gives rise to the occurrence and development of COPD. Complement component 1q (C1q), as a subcomponent of the C1 complex, could be involved in innate and adaptive immunity. Our study aimed to investigate the relationship between C1q and the clinical characteristics of COPD subjects.

Patients and Methods

Serum C1q levels were measured in 203 COPD subjects and 191 non-COPD controls. Correlations between C1q and the characteristics of COPD were analyzed using Spearman’s rho. Receiver operating curve (ROC) analysis was used to evaluate the threshold value in differentiating disease status. All 203 COPD subjects were followed up for 1 year for future acute exacerbations.

Results

There were significant reductions in serum C1q levels in COPD subjects compared to non-COPD controls. Moreover, serum C1q levels were obviously positively correlated with the FEV1/FVC ratio and predicted FEV1% but had a weakly negative correlation with the %LAA-950 and the percentage of neutrophils in peripheral blood. Using a cutoff value of 137.150 mg/l as the boundary in ROC analysis, the sensitivity and specificity were 65.9% and 76.0%, respectively. The 1-year follow-up results showed that C1q levels less than 137.150 mg/l were negatively related to the time to the next severe exacerbation and the time to death.

Conclusion

Circulating C1q levels may be a novel biomarker not only related to the pulmonary function of COPD but also having great potential to predict the risk of COPD deterioration in the future. However, further prospective trials are needed to clarify the influences of C1q on the pathogenesis of COPD.

Keywords:

• complement component 1q
• chronic obstructive pulmonary disease
• pulmonary function
• exacerbations
• future risk

Acknowledgments

This work was supported by grants of The National Key Research and Development Program of China (No. 2016YFC1304601). The funders had no role in research design, data collection or analysis, and writing manuscripts.

Author Contributions

Ke Zhang, Chunyan Zheng designed this research, and all authors made a great contribution to acquisition of data, statistical analysis, drafting, revising and critically reviewing the article, gave final approval of the version to be published and agree to be accountable for all aspects of the work.

Disclosure

All authors declare no conflicts of interest related to this work.