We observed significantly elevated release of proinflammatory cytokines, including IL-6, IL-8, MIP-1α, MCP-1, MCP-3, VCAM-1 and MIP-1β, from lung fibroblasts (HLFs) derived from CTD-IP patients (n = 4) with pathologically diagnosed usual interstitial pneumonia (UIP) (CTD-UIP HLFs), compared with NHLFs (Fig. 4c, P < 0.05 or P < 0.01). Here, CCL2 is linked to idiopathic pulmonary fibrosis.