Moreover, we found a positive correlation between MCP-1 serum levels and RA duration in RA-ILD+ patients, which is in line with its key endothelial function reported in RA (Hayashida et al., 2001; Rantapää-Dahlqvist et al., 2007; Deshmane et al., 2009; Lin et al., 2014). Here, CCL2 is linked to interstitial lung disease.