Apocynin Abrogates Methotrexate-induced Nephrotoxicity: Role of TLR4/NF-κB-p65/p38-MAPK, IL-6/STAT-3, PPAR-γ, and SIRT1/FOXO3 Signaling Pathways

The present study was designed to evaluate the potential renoprotective impacts of apocynin (APC) against nephrotoxicity induced by methotrexate (MTX) administration. To fulfill this aim, rats were allocated into four groups: control; APC (100 mg/kg/day; orally); MTX (20 mg/kg; single intraperitoneal dose at the end of the 5th day of the experiment); and APC +MTX (APC was given orally for 5 days before and 5 days after induction of renal toxicity by MTX). On the 11th day, samples were collected to estimate kidney function biomarkers, oxidative stress, pro-inflammatory cytokines, and other molecular targets. Compared to the MTX control group, treatment with APC significantly decreased urea, creatinine, and KIM-1 levels and improved kidney histological alterations. Furthermore, APC restored oxidant/antioxidant balance, as evidenced by a remarkable alleviation of MDA, GSH, SOD, and MPO levels. Additionally, the iNOS, NO, p-NF-κB-p65, Ace-NF-κB-p65, TLR4, p-p38-MAPK, p-JAK1, and p-STAT-3 expressions were reduced, while the IκBα, PPAR-γ, SIRT1, and FOXO3 expressions were significantly increased. In NRK-52E cells, MTX-induced cytotoxicity was protected by APC in a concentration-dependent manner. In addition, increased expression of p-STAT-3 and p-JAK1/2 levels were reduced in MTX-treated NRK-52E cells by APC. The in vitro experiments revealed that APC-protected MTX-mediated renal tubular epithelial cells were damaged by inhibiting the JAK/STAT3 pathway. Besides, our in vivo and in vitro results were confirmed by predicting computational pharmacology results using molecular docking and network pharmacology analysis. In conclusion, our findings proved that APC could be a good candidate for MTX-induced renal damage due to its strong antioxidative and anti-inflammatory bioactivities.