Pirfenidone (PFD) is an oral anti-fibrotic drug used for idiopathic pulmonary fibrosis (IPF) therapy. We determined the role of activating transcription factor 3 (ATF3) and the effect of PFD on fibroblast to myofibroblast transition (FMT) in rheumatoid arthritis-associated interstitial lung disease (RA-ILD).
RA-ILD lung specimens were obtained by CT-guided percutaneous transthoracic biopsy. A pulmonary fibrosis mouse model was established by the intratracheal injection of bleomycin. Pathological variation and the expression of α-SMA and ATF3 were observed by H&E, Masson and immunofluorescence staining. Primary human lung fibroblasts (pHLFs) were isolated from lung tissues that were pathologically confirmed to be normal by pneumonectomy. Cell viability was detected using an MTT assay. Cell migration and invasion were detected using a Transwell chamber. The protein levels of α-SMA, ATF3, Smad3 and p-Smad3 were measured by Western blot. HLFs were infected with lentiviruses expressing ATF3 or scrambled shRNA.
ATF3 was dramatically upregulated in lung tissues from both bleomycin-induced mice and patients with RA-ILD compared with controls. The upregulation of ATF3 and the accumulation of collagen in the lung tissues of mice with pulmonary fibrosis were reduced by PFD. PFD significantly inhibited increases in the proliferation, invasion and migration of pHLFs stimulated by TGF-β1. Moreover, we observed the inhibitory effect of PFD on FMT via the downregulation of ATF3, which was further confirmed in ATF3 knockdown (KD) pHLFs.
This work shows the inhibitory effect of PFD on FMT in pHLFs, which is mediated by the downregulation of ATF3. Our findings suggest that PFD might have therapeutic potential for the treatment of RA-ILD.