CD146 deficiency aggravates chronic obstructive pulmonary disease via the increased production of S100A9 and MMP-9 in macrophages

Chronic obstructive pulmonary disease (COPD) is a leading cause of global death. As a molecule beyond adhesion, CD146 is involved in COPD pathogenesis. However, the mechanisms of CD146 in COPD remain largely elusive. We hypothesized that CD146 regulates the production of matrix metalloproteinase-9 (MMP-9) in macrophages and thereby contributes to COPD. Here, we constructed a murine model of COPD using lipopolysaccharide (LPS) and porcine pancreatic elastase (PPE). In COPD-like mice, LPS and PPE decreased the pulmonary expression of CD146. MMP-9 expression and bioactivity were increased in CD146 knockout COPD-like mice. In vitro, LPS decreased CD146 expression in macrophages. With or without LPS challenge, CD146-defective macrophages produced more MMP-9. Transcriptome analysis based on next-generation sequencing (NGS) revealed that S100A9 regulated MMP-9 production in CD146-defective macrophages. Targeting S100A9 with paquinimod decreased lung inflammation and alleviated alveolar destruction in COPD-like mice. Collectively, our study suggests that CD146 negatively regulates MMP-9 production in macrophages via the S100A9 pathway in COPD.