Paraxanthine and azilsartan attenuate gentamicin-induced renal fibrosis via modulation of TGF-β1/Smad3/7 signaling and miRNA-21/miRNA-200b expression

BACKGROUND: Renal fibrosis is a key contributor to chronic kidney disease progression. The TGF-β1/Smad signaling pathway, particularly Smad2 and Smad3 mediate pro-fibrotic responses, while Smad7 exerts inhibitory effects. AIM: The study aimed to evaluate the therapeutic potential of paraxanthine (Para), an active caffeine metabolite, and azilsartan (Azil), an angiotensin II receptor blocker, in attenuating gentamicin (GM)-induced renal fibrosis through targeting Smad pathway and miRNA-21/200b. METHODS: Seventy male albino mice were randomized into seven groups (n = 10): Control, GM, SIS3 + GM, Para + GM, Azil + GM, Para + SIS3 + GM, and Azil + SIS3 + GM. GM (40 mg/kg, I.P.) was administered daily for 7 days. Subsequently, Para (20.5 mg/kg) and Azil (5 mg/kg) were given orally, while SIS3 (2 mg/kg, I.P.) was administered for 7 days. Serum and urine renal function markers were measured. Renal histopathology, protein expression of TGF-β1, CTGF, Smad3, Smad2 and Smad7, and gene expression of miRNA-21 and miRNA-200b were evaluated. RESULTS: GM caused significant (p < 0.001) nephrotoxicity with elevated BUN, serum creatinine, urinary albumin/creatinine ratio, and KIM-1 and increased fibrosis and marked type I collagen deposition compared to normal control. However, treatments with Para & Azil resulted in significant (p < 0.05) improvement in renal functions. Pro-fibrotic markers TGF-β1, connective tissue growth factor (CTGF), Type I Collagen, Smad 2 and Smad3 were reduced, while Smad7 was increased in treated groups versus GM group. Additionally, miRNA-21 was downregulated and miRNA-200b was upregulated following treatments. CONCLUSION: Paraxanthine and azilsartan demonstrated significantl restoring of kidney function and suppressing fibrotic progression. Their actions were mediated through regulation of Smad3/7 signaling and modulation of miRNA-21 and miRNA-200b expression, highlighting these pathways as promising therapeutic targets for the treatment of renal fibrosis.