Yohimbine treatment improves pulmonary fibrosis by attenuating the inflammation and oxidative stress via modulating the MAPK pathway

Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disorder characterized by the accumulation of extracellular matrix and collagen, resulting in significant parenchymal scarring and respiratory failure that leads to mortality. Yohimbine (YBH) is an α-2 adrenergic receptor antagonist with anti-oxidant and anti-inflammatory properties. In the current study, we aimed to investigate the anti-inflammatory, anti-oxidant and anti-fibrotic activity of YBH against LPS/TGF-β-induced differentiation in BEAS-2B/LL29 cells and bleomycin (BLMN) induced pulmonary fibrosis model in rats. Network pharmacology, gene expression, Western-blot analysis, immune-cytochemistry/immunohistochemistry, lung functional analysis, and histology techniques were used to assess the fibrotic marker expression/levels in cells or rat lung tissues. YBH treatment significantly attenuated the LPS-induced pro-inflammatory (identified through a network-pharmacology approach) and oxidative stress markers expression in lung epithelial cells. TGF-β stimulation significantly elevated the fibrotic cascade of markers and treatment with YBH attenuated these markers’ expression/levels. Intra-tracheal administration of BLMN caused a significant elevation of various inflammatory/oxidative stress and fibrotic markers expression in lung tissues and treatment with YBH significantly mitigated the same. Ashcroft score analysis revealed that BLMN exhibited severe distortion of the lungs, elevation of thickness of the alveolar walls and accumulation of collagen in tissues, further treatment with YBH significantly suppressed these events and improved the lung architecture. Lung functional parameters demonstrated that BLMN-induced stiffness and resistance were reduced considerably upon YBH treatment and restored lung function dose-dependently. Overall, this study reveals that YBH treatment significantly attenuated the BLMN-induced fibrosis by regulating the MAPK pathway and provided insightful information for progressing towards translational outcomes.