Maimendong decoction modulates the PINK1/Parkin signaling pathway alleviates type 2 alveolar epithelial cells senescence and enhances mitochondrial autophagy to offer potential therapeutic effects for idiopathic pulmonary fibrosis

Abstract

Ethnopharmacological relevance: Maimendong decoction (MMDD) originates from the ancient Chinese medical text Synopsis of the Golden Chamber and is a well-established remedy for treating lung diseases. It has demonstrated efficacy in the long-term clinical management of idiopathic pulmonary fibrosis (IPF); however, its underlying mechanisms remain unclear.

Aim of the study: This study investigates whether MMDD alleviates IPF by reducing type 2 alveolar epithelial cell (AEC2) senescence and enhancing mitochondrial autophagy. It also explores whether these effects are mediated through the PTEN-induced putative kinase 1 (PINK1)/Parkinson juvenile disease protein 2 (Parkin) pathway.

Materials and methods: An IPF mouse model was established with bleomycin (BLM). Mice were administered MMDD, pirfenidone (PFD), or saline for 7 or 28 days. Body weight, lung coefficient, and lung appearance were monitored, and lung tissue pathology was assessed. The expression levels of p53, p21, p16, SA-β-gal activity, and senescence-associated secretory phenotype (SASP) markers were measured. Ultrastructural changes in AEC2 mitochondria were analyzed using transmission electron microscopy. Protein levels of autophagy markers sequestosome-1 and light chain 3 were assessed. The protein levels of PINK1, Parkin, and phosphorylated Parkin were further assessed using network pharmacology analysis and molecular docking technology.

Results: MMDD alleviated BLM-induced IPF by improving body weight, lung appearance, and histopathological features. It reduced AEC2 senescence markers, including p53, p21, p16, SA-β-gal, and SASP, while enhancing mitochondrial autophagy and repairing mitochondrial damage. Network pharmacology and molecular docking identified PINK1 as a major target, and Western blot (WB) analysis confirmed that MMDD regulates the PINK1/Parkin signaling pathway in the treatment of IPF.

Conclusions: MMDD regulates the PINK1/Parkin signaling pathway, alleviates AEC2 senescence, and enhances mitochondrial autophagy, providing significant therapeutic potential for IPF treatment.

Keywords: Cell senescence; Idiopathic pulmonary fibrosis; Maimendong decoction; Mitochondrial autophagy; Type 2 alveolar epithelial cells.