The Mitigated Effect of the Combination of Metformin and Stearic Acid to Ameliorate Bleomycin‐Induced Pulmonary Fibrosis in Rats via Inhibiting Gal‐3/Smad3/α‐SMA and TNF‐α/NF‐κβ Signaling Pathways

Pulmonary fibrosis (PF) is a chronic, inflammatory interstitial lung disease. It is promoted by overproliferation of fibroblasts characterized by the progressive formation of scar tissue in the lung parenchyma, which leads to an inexorable decline in lung function, respiratory failure, and high mortality. This study aims to assess the synergetic consequences of metformin and stearic acid, whether individually or in combination, to ameliorate bleomycin-induced PF in rat models via suppressing Gal-3/Smad3/α-SMA and TNF-α/NF-κβ signaling pathways and mitigate its adverse side effect on kidneys and liver. The antioxidant/oxidative stress shuttle system was estimated in lung, liver, and kidney tissues. Moreover, histopathology assessment and immunohistochemical staining for NF-κβ antibodies were performed in the lung and trachea tissues. Additionally, RT-qPCR gene expressions of TNF-α, IL-1β, IL-6, and α-SMA were investigated. The expression levels of Gal-3, p-Gal-3, Smad3, and p-Smad3 protein in lung tissues were determined by western blot analysis. The findings showed that metformin and/or stearic acid exhibited antifibrotic and anti-inflammatory impacts in-vivo as evidenced by enhanced body weight, liver and kidney functions, reduced oxidative stress, increased endogenous antioxidant enzymes, downregulated inflammatory cytokine levels IL-1β, IL-6, and TNF-α, and attenuation effect on α-SMA, a major marker of myofibroblasts. Furthermore, there was a marked improvement in the profibrotic Gal-3/Smad3 signaling pathway. On the other hand, a significant reduction in the histological score of fibrosis and immunohistochemical expression NF-κβ levels was detected, especially in the combination-treated group. Overall, our findings elucidate the synergetic antifibrotic impact of metformin and stearic acid which could be used as a potential candidate drug against various chronic inflammatory diseases.