Dehydroepiandrosterone alleviates pulmonary fibrosis by modulating the TLR4/NF-κB/NLRP3 signaling cascade in macrophages

Idiopathic pulmonary fibrosis (IPF) is a severe progressive lung disease with limited treatment options. Dehydroepiandrosterone (DHEA), an endogenous steroid hormone, possesses anti-inflammatory and anti-fibrotic properties, but its mechanism of action in pulmonary fibrosis (PF) remains incompletely understood. This study aimed to investigate whether DHEA alleviates PF by modulating macrophage-driven inflammatory responses. An in vitro model of PF was established using conditioned medium from LPS-stimulated, PMA-differentiated THP-1 macrophages to treat MRC-5 pulmonary fibroblasts. DHEA pretreatment (5–20   μM) was applied to macrophages, and the TLR4-specific inhibitor TAK-242 was used for mechanistic validation. Inflammatory cytokines were measured by ELISA, protein expression of TLR4/NF-κB/NLRP3 cascade components and extracellular matrix markers (α-SMA, Collagen I) by Western blotting, and cell proliferation by CCK-8 and flow cytometry. DHEA significantly reduced LPS-induced secretion of TNF-α, IL-6, IL-1β, and IL-18 from macrophages. It downregulated TLR4 expression, inhibited NF-κB phosphorylation, and suppressed NLRP3 inflammasome activation (NLRP3, ASC, Caspase-1). Furthermore, DHEA treatment of macrophages prevented their conditioned medium from inducing abnormal proliferation of MRC-5 cells and reduced α-SMA and Collagen I expression in these fibroblasts, similar to the effects of TAK-242. In conclusion, DHEA alleviates inflammatory responses and in vitro pulmonary fibrosis by blocking the TLR4/NF-κB/NLRP3 signaling cascade in macrophages, providing a new mechanistic basis for its potential therapeutic application in PF.