Potential Effect of Etoricoxib in Reducing Inflammation in Methotrexate-Induced Pulmonary Injury in Rats: Role of Oxidative Stress and the TLR4/p38-MAPK/NF-κB Signaling Pathway

Numerous chemotherapeutic medications can have hazardous effects on the lungs, which can result in severe lung diseases. Methotrexate (MTX) is prescribed for cancer and inflammation-related disorders; nevertheless, it is exceptionally highly toxic and has multiple kinds of adverse reactions, including pulmonary injury. Our work was designed to demonstrate the ability of etoricoxib (ETO) to mitigate MTX-induced lung injury in experimental animals. Adult male Wistar rats were separated into four groups. The first group consisted of healthy controls that received carboxymethyl cellulose (1 ml/day, p.o.), the second group received a single dose of MTX (20 mg/kg/day, i.p.), the third group received ETO (10 mg/kg/day, p.o.) for three weeks, and the fourth group first received a single MTX (20 mg/kg, i.p.) and then was treated with ETO for three weeks. Concomitant treatment with ETO and MTX improved the histological structure of the lung tissue. It significantly altered the levels of oxidant/antioxidant markers, such as malondialdehyde (MDA), heme oxygenase-1 (HO-1), reduced glutathione (GSH), and nuclear factor erythroid 2-related factor 2 (Nrf-2), in favor of antioxidants. Moreover, ETO can normalize the proinflammatory cascade, which includes tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β). At the molecular level, ETO downregulated the protein expression of toll-like receptor 4 (TLR4), nuclear factor kappa-B (NF-κB), and p38 mitogen-activated protein kinase (p38 MAPK) in inflamed rat lungs. In conclusion, our findings indicate that oral administration of ETO ameliorates MTX-induced lung injury by inhibiting oxidative stress and suppressing the TLR4/NF-κB and TLR4/p38-MAPK inflammatory signaling pathways.