Pirfenidone alleviates interstitial lung disease in mice by inhibiting neutrophil extracellular trap formation and NLRP3 inflammasome activation

BackgroundIdiopathic inflammatory myopathy (IIM) is a progressive autoimmune disease characterized by interstitial lung disease (ILD) with limited therapeutics available. Pirfenidone (PFD), a medication utilized for the treatment of idiopathic pulmonary fibrosis, exhibits notable antioxidant, anti-inflammatory and inhibition of collagen synthesis. This study aims to clarify its efficacy and mechanism in treating IIM-ILD.MethodsA murine myositis-associated interstitial lung disease (MAILD) model was used to assess the therapeutic effect of PFD. The serum levels of IL-1β, IL-6 and TNF-α were detected by ELISA. PFD was utilized to disrupt neutrophil extracellular traps (NETs) formation in vitro, and its inhibitory effect on NETs was assessed through immunohistochemistry of CitH3 and MPO in the lung tissue and the serum cfDNA level in mice. Immunohistochemical and western blot was utilized to examine alterations in epithelial-mesenchymal transition (EMT) and NLRP3 inflammasome markers.ResultsPFD treatment inhibited pulmonary inflammation and fibrosis in the MAILD model. PFD intervention reduced NETs formation in vitro. PFD treatment significantly reduce NETs infiltration in the lung tissue and the level of cfDNA in the serum of mice. Additionally, PFD down-regulated EMT and NLRP3-related proteins in vivo. PFD treatment also notably reduced serum levels of IL-1β, IL-6 and TNF-α. After NETs stimulation, A549 cells exhibited EMT and activation of NLRP3 inflammasome. PFD attenuated EMT in A549 cells and suppressed the activation of NLRP3 inflammasome.ConclusionPFD alleviates ILD in a murine MAILD model by inhibiting NETs formation and NLRP3 inflammasome activation, suggesting that PFD might be a potential therapeutic agent for IIM-ILD.