Urolithin A attenuates pulmonary fibrosis via the PI3K/AKT/mTOR pathway: Evidence from network pharmacology and experimental validation

Abstract

Objective: Pulmonary fibrosis(PF) is an abnormal wound-healing response resulting from recurrent alveolar injury, characterized by persistent inflammation and excessive collagen deposition. Given the limited clinical treatment options, novel therapeutic strategies are urgently needed. Urolithin A (UA), a secondary metabolite produced by intestinal microbiota from natural polyphenols, has attracted attention due to its anti-inflammatory, antioxidant, and anti-aging properties. However, the therapeutic efficacy and mechanisms of UA in PF remain unclear. This study aimed to investigate the protective effects and underlying molecular mechanisms of UA in PF.

Methods: This study integrated network pharmacology analysis, molecular docking, and in vitro/in vivo experiments to elucidate the anti-fibrotic mechanisms of UA. Firstly, a mouse model of PF was established via intratracheal instillation of bleomycin. Mice in the UA treatment group received daily oral administration of UA (20 mg/kg/day) starting on day 10 post-modeling and continuing until day 21, at which point lung tissues were collected. Histopathological alterations and collagen deposition in the lungs were assessed using Masson's trichrome staining and hydroxyproline content analysis. Furthermore, network pharmacology was employed to predict the potential molecular targets and pathways of UA, which were further validated through molecular docking and in vitro fibroblast experiments to verify the underlying mechanisms.

Results: UA treatment significantly alleviated PF in mice, evidenced by reduced collagen deposition, diminished structural damage, and notably decreased excessive extracellular matrix accumulation. Network pharmacology analysis and molecular docking indicated that the PI3K/AKT/mTOR signaling pathway is the primary pharmacological target of UA's anti-fibrotic effect. Further in vitro experiments demonstrated that UA significantly suppressed fibroblast activation by inhibiting AKT1 phosphorylation. Moreover, the inhibitory effects of UA on fibroblasts were reversed upon reactivation of the AKT pathway by the AKT agonist SC79, further confirming the crucial role of the AKT signaling pathway in UA's anti-fibrotic mechanism.

Conclusion: UA exerts therapeutic effects on PF by targeting the PI3K/AKT/mTOR pathway, particularly through the inhibition of AKT1 phosphorylation. These findings indicate that UA has potential as a therapeutic candidate for PF and provide a novel perspective for utilizing gut microbiota metabolites in the treatment of fibrotic diseases. Further studies are needed to elucidate the precise mechanisms of UA.

Keywords: Fibroblast activation; Network pharmacology; PI3K/AKT/mTOR pathway; Pulmonary fibrosis; Urolithin A.