Apremilast ameliorates methotrexate-induced renal injury in rats: role of TLR4/NF-κB/P38 MAPK/caspase-3 and Nrf2/HO-1 signaling pathways.

This study aimed to assess the preventive potential of apremilast (APRE) against methotrexate (MTX)-induced renal damage in rats through modulation of nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling and toll-like receptor 4/nuclear factor-kappa B/p38 mitogen-activated protein kinase/caspase-3 (TLR4/NF-κB/p38 MAPK/Caspase-3) signaling pathways. Four groups of male Wistar albino rats were assigned: control, APRE, MTX, MTX + APRE. Histopathological investigation and biochemical analysis of the serum renal damage indicators (urea and creatinine) were used to evaluate the renal toxicity of MTX. Testing for renal malondialdehyde (MDA) and reduced glutathione (GSH) was conducted. The levels of renal tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), Nrf2, HO-1, and cleaved caspase-3 were measured using the ELISA method. Using an immunohistochemistry method, the expression of NF-κB p65 in the kidney was investigated. Western blotting was used to examine the expression of TLR4 and p38 MAPK proteins. MTX administration resulted in significant renal injury, as evidenced by elevated serum urea and creatinine levels. The kidneys were significantly affected as evidenced by histopathological alterations and increased levels of renal MDA, TNF-α, IL-6, Bcl-2-associated x (Bax), and cleaved caspase-3, alongside decreased levels of GSH and B-cell lymphoma 2 (Bcl-2) expression. These outcomes were linked to inhibition of Nrf2/HO-1 signaling and activation of the TLR4/NF-κB/p38 MAPK/Caspase-3 pathway. Co-treatment with APRE at 20 mg/kg/day for 21 days markedly improved all biochemical and pathological alterations evoked by MTX, demonstrating significant nephroprotective effects. Apremilast inhibits methotrexate's harmful effects on the kidneys by activating signaling cascades that include Nrf2/HO-1, while simultaneously downregulating TLR4/NF-κB/p38 MAPK/Caspase-3.