Trilobatin ameliorates pulmonary fibrosis by directly targeting MEK1 to antagonize TGF-β-driven...

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterized by limited therapeutic options and a poor prognosis. Trilobatin (TLB), a natural dihydrochalcone extracted from Lithocarpus polystachyus, possesses diverse bioactivities; however, its anti-fibrotic potential and underlying mechanisms remain poorly defined. Here, we demonstrate that TLB effectively mitigates bleomycin (BLM)-induced pulmonary fibrosis in vivo and suppresses transforming growth factor-beta 1 (TGF-β1)-driven epithelial-mesenchymal transition (EMT) in vitro. In fibrotic mice, TLB treatment significantly attenuated pro-inflammatory cytokine secretion, limited inflammatory cell infiltration, preserved alveolar architecture, and decreased collagen deposition, ultimately leading to improved survival rates. Through network pharmacology and molecular docking, we identified MEK1 as a primary molecular target of TLB, an interaction subsequently validated by the Cellular Thermal Shift Assay (CETSA). Mechanistically, TLB directly uncoupled the TGF-β-induced ERK signaling cascade by selectively inhibiting the phosphorylation of MEK1 and ERK1/2, without affecting the upstream activation of Raf1. Furthermore, pharmacological hyperactivation of MEK1 via forskolin abrogated the protective effects of TLB against EMT and fibrogenesis. Collectively, our findings reveal a previously unrecognized anti-fibrotic mechanism of TLB, suggesting that this natural small molecule is a promising therapeutic candidate for IPF by specifically targeting MEK1-dependent ERK signaling.