GAMG ameliorates silica-induced pulmonary inflammation and fibrosis via the regulation of EMT and NLRP3/TGF-β1/Smad signaling pathway

Silicosis is an occupational disease caused by exposure to silica characterized by pulmonary inflammation and fibrosis, for which there is a lack of effective drugs. Glycyrrhetinic acid 3-O-β-D-glucuronide (GAMG) can treat silicosis due to its anti-inflammatory and anti-fibrotic properties. Here, the effect of therapeutic interventions of GAMG was evaluated in early-stage and advanced silicosis mouse models. GAMG significantly improved fibrotic pathological changes and collagen deposition in the lungs, alleviated lung inflammation in the BALF, reduced the expression of TNF-α, IL-6, NLRP3, TGF-β1, vimentin, Col-Ⅰ, N-cadherin, and inhibited epithelial-mesenchymal transition (EMT), thereby ameliorating pulmonary fibrosis. Moreover, the dose of 100 mg/kg GAMG can effectively prevent early-stage silicosis, while that of 200 mg/kg was recommended for advanced silicosis. In vitro and in vivo study verified that GAMG can suppress EMT through the NLRP3/TGF-β1/Smad2/3 signaling pathway. Therefore, GAMG could be a promising preventive (early-stage silicosis) and therapeutic (advanced silicosis) strategy, which provides a new idea for formulating prevention and treatment strategies.