All-trans-retinoic acid and valproic acid: A combinatorial approach for the treatment of nephrotic syndrome

Abstract

Massive proteinuria, oedema, hypoalbuminemia, and hyperlipidemia are the hallmarks of nephrotic syndrome (NS). Recently, epigenetic pathways in renal diseases have been identified. The present work hypothesizes using the combination of two epigenetic drugs all-trans retinoic acid (ATRA) and valproic acid (VPA) as a prospective treatment method to lessen NS-related glomerulosclerosis, fibrosis, and increased renal function parameters along with attenuating inflammation and improving overall mitochondrial health. To induce NS, doxorubicin (8.5 mg/kg, n = 6) was injected intravenously into female Sprague Dawley rats. After 28 days, ATRA and VPA were orally administered to the rats, alone and in combination at a dose of 5 mg/kg (n = 6) and 200 mg/kg (n = 6) in sesame oil and saline, respectively. Prednisolone (3 mg/kg in saline; n = 6) was used as standard. Following 21-day treatment period, the rats were sacrificed prior to which 24 hrs urine samples were obtained. Blood samples were collected and kidneys were extracted for further analyses. Renal function parameters (proteinuria, BUN, albumin, creatinine), levels of tissue reengineering and fibrosis markers (TGF-β, MMP2 activity), cholesterol and triglyceride levels were significantly improved in the ATRA and VPA combination group as compared to positive control group. Histopathological analyses revealed a reduction in inflammation, glomerulosclerosis and fibrosis. The inflammatory markers, namely TNF-α, IL-1β, IL-6, NF-κB, determined by ELISA were downregulated. Mitochondrial biogenesis markers viz. PGC-1α, TFAM, NRF1, Nrf2, PPAR-γ, KEAP-1, analysed by RT-qPCR were upregulated thereby showing a significant improvement in the combination group as compared to positive control and standard group. The study overall contributes to a novel approach to treating NS and our findings will surely drive additional exploratory preclinical and clinical studies.