Crocin attenuates lung inflammation and pulmonary vascular dysfunction in a rat model of bleomycin-induced pulmonary fibrosis

Amongst the various forms of lung injury; pulmonary fibrosis remains the most intricate form with limited therapeutic options to both the patient and the physicians. Bleomycin (BLM) is a chemotherapeutic agent used for the treatment of various carcinomas; however, its therapeutic value is significantly limited by its associated pulmonary fibrosis. The current study highlights the prominent antioxidant, anti-inflammatory and anti-fibrotic effect of crocin against BLM-induced pulmonary fibrosis. Intratracheal BLM instillation induced significant biochemical, structural, functional and vascular pulmonary injury. BLM instillation increased oxidant load with quenching of antioxidant defenses together with increase inflammatory and fibrotic cytokines expression. Crocin significantly attenuated BLM-induced lung injury and its effect was comparable to the standard anti-fibrotic; halofuginone. The observed anti-inflammatory and anti-fibrotic and antioxidant impacts are thought to be embroiled in the therapeutic impacts of crocin. Down-regulation of TLR4, IL-10 expression is the major pathway involved in the observed anti-inflammatory effects and finally, down-regulation of tissue expression of TNF-α and TGF-β1 is the major pathways implicated in the observed anti-fibrotic activities and modulation of Nrf2 and HO-1 pathways is the main mechanism involved in the observed antioxidant effects.