RESUMEN
Specific relationships among reactive oxygen species, activation pathways, and inflammatory mechanisms involved in kidney injury were assessed in a combined model of obesity and hyperoxaluria. Male Wistar rats were divided into four groups: Control, HFD (high fat diet), OX (0.75% ethylene glycol), and HFD + OX (combined model) Changes in basal O2- levels were evaluated by chemiluminescence in renal interlobar arteries and renal cortex. Furthermore, the effect of different inhibitors on NADPH-stimulated O2- generation was assessed in renal cortex. Oxidative stress sources, and local inflammatory mediators, were also determined, in parallel, by RT-PCR, and correlated with measures of renal function, urinary biochemistry, and renal structure. Rats from the HFD group developed overweight without lipid profile alteration. Tubular deposits of crystals were seen in OX and severely enhanced in HFD + OX groups along with a significantly higher impairment of renal function. Basal oxidative stress was increased in renal cortex of OX rats and in renal arteries of HFD rats, while animals from the combined HFD + OX group exhibited the highest levels of oxidative stress in renal cortex, derived from xanthine oxidase and COX-2. NADPH oxidase-dependent O2- generation was elevated in renal cortex of the OX group and markedly enhanced in the HFD + OX rats, and associated to an up-regulation of Nox1 and a down-regulation of Nox4 expression. High levels of oxidative stress in the kidney, of OX and HFD + OX groups were also associated to an inflammatory response mediated by an elevation of TNFα, COX-2, NFκB1 MCP-1, and OPN. Oxidative stress is a key pathogenic factor in renal disease associated to hyperoxaluria and a common link underlying the exacerbated inflammatory response and kidney injury found under conditions of both obesity and hyperoxaluria. Nox1 pathway must be considered as a potential therapeutic target.
Asunto(s)
Hiperoxaluria/complicaciones , Hiperoxaluria/metabolismo , Enfermedades Renales/etiología , NADPH Oxidasa 1/metabolismo , Obesidad/complicaciones , Obesidad/metabolismo , Estrés Oxidativo/fisiología , Animales , Modelos Animales de Enfermedad , Masculino , Ratas , Ratas WistarRESUMEN
Metabolic syndrome (MS) individuals have a higher risk of developing chronic kidney disease through unclear pathogenic mechanisms. MS has been also related with higher nephrolithiasis prevalence. To establish the influence of MS on renal function, we designed a murine model of combined metabolic syndrome and hyperoxaluria. Four groups of male Sprague-Dawley rats were established: (1) control group (n = 10) fed with standard chow; (2) stone former group (SF) (n = 10) fed with standard chow plus 0.75% ethylene glycol administered in the drinking water; (3) metabolic syndrome group (MS) (n = 10), fed with 60% fructose diet; (4) metabolic syndrome + stone former group (MS + SF) (n = 10), 60% fructose diet and 0.75% EG in the drinking water. MS group showed a significant injury to renal function when hyperoxaluria was induced. It was demonstrated by a significant decrease of creatinine clearance (p < 0.001), with higher tubular damage (34.3%, CI 95% 23.9-44.7, p < 0.001), produced by deposition of crystals, and increased tubular synthesis of osteopontin as a response to tubular damage. Induction of hyperoxaluria in rats with MS causes severe morphological alterations with a significant impairment of renal function. This impairment is not produced in rats without MS. Therefore, this model can be useful for the study of the influence of MS in stone formation.