RESUMEN
BACKGROUND: Nephrotic syndrome (NS) is a clinical state characterized by massive proteinuria and excessive fluid retention. The effects of early versus late treatment with low or high doses of oral everolimus, a mammalian target of rapamycin inhibitor, on proteinuria in NS have not been previously described. METHODS: The effects of early treatment (2 days prior to NS induction) versus late treatment (beginning 2 weeks following the establishment of NS) with a low (20 mg/L) or high (100 mg/L) dose of everolimus for 5-7 weeks on proteinuria and nephrin/podocin abundance were assessed in male adult SD rats with adriamycin-induced NS. RESULTS: Adriamycin caused a significant increase in daily and cumulative proteinuria throughout the experimental period. Early, and to a lesser extent late treatment, with a low dose of everolimus, significantly decreased both daily and cumulative proteinuria and improved renal function. The anti-proteinuric effects of low-dose everolimus were associated with restoration of the disruptive glomerular nephrin/podocin abundance. In contrast, administration of a high dose of everolimus resulted in a decrease in proteinuria in NS rats, subsequently to deterioration of renal function. CONCLUSIONS: Early, and to a lesser extent late treatment, with a low but not a high dose of everolimus is effective in reducing proteinuria in nephrotic rats. The mechanism may be via nephrin/podocin protection.