Abstract
Cyclosporine A (CSA), a critical immunosuppressant, induces nephrotoxicity through oxidative stress and inflammatory pathways, limiting its clinical utility. Natural compounds like Nigella sativa oil (NSO) and Echinacea purpurea extract (EPE) possess antioxidant and immunomodulatory properties, but their combined mechanistic action against CSA toxicity is unexplored. This study investigated the protective mechanisms of NSO and EPE, individually and in combination, against CSA-induced renal and immunological toxicity in rats. Fifty male Wistar rats were divided into five groups (n = 10/group): Control, CSA (cyclosporine A, 15 mg/kg/day, i.p.), CSA + NSO (Nigella sativa oil, 200 mg/kg/day, p.o.), CSA + EPE (Echinacea purpurea extract, 200 mg/kg/day, p.o.), and CSA + NSO+EPE (100 mg/kg/day each, p.o.). After 30 days, renal and bone marrow tissues were analyzed for oxidative stress and redox status markers (malondialdehyde, MDA; reduced glutathione, GSH; oxidized glutathione, GSSG) and the antioxidant transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2), alongside the pro-inflammatory mediator TNF-α (tumor necrosis factor-alpha). Gene expression of renal injury biomarkers (Tlr4, toll-like receptor 4; Tgfb1, transforming growth factor-β1; Lcn2, lipocalin-2; Kim1, kidney injury molecule-1) and bone marrow immunomodulatory cytokines (Il2, interleukin-2; Il6, interleukin-6; Il17a, interleukin-17 A; Ifng, interferon-γ) was also assessed. Serum hepatic (AST, aspartate aminotransferase; ALT, alanine aminotransferase) and renal (creatinine, urea) function parameters, along with hematological parameters, were also evaluated. CSA significantly (p < 0.05) induced oxidative stress (↑MDA, ↑GSSG; ↓GSH, ↓Nrf2) and inflammation (↑TNF-α) in kidney and bone marrow. It upregulated renal pro-fibrotic and injury genes (Tlr4, ~ 2.9-fold; Tgfb1, ~ 4.9-fold; Lipocalin-2, ~ 3.9-fold; Kim1, ~ 4.3-fold) and severely downregulated bone marrow cytokines (Il2, Il6, Il17a, Ifng; up to ~ 80%). Co-treatment with NSO and EPE, particularly in combination, potently reversed these effects. The combination therapy most effectively normalized oxidative balance, suppressed TNF-α, enhanced Nrf2, mitigated the expression of renal injury genes, and significantly restored the expression of key bone marrow cytokines towards control levels, concurrently improving serum creatinine, urea, and hematological profiles. NSO and EPE confer protection against CSA toxicity through a multi-mechanistic approach: potentiation of the Nrf2 antioxidant pathway and concomitant suppression of TLR4-mediated inflammatory and TGF-β1-driven fibrotic signaling. Their combination offers a superior therapeutic strategy to harness CSA's immunosuppressive benefits while alleviating its detrimental renal and immunological side effects.