RESUMO
Women with preeclampsia (PE) form a vulnerable group for vitamin D3 deficiency. Reabsorption of vitamin D3 occurs in the proximal tubule after being endocytosed in combination with DBP (vitamin D binding protein) by the megalin/cubilin receptor. Because proteinuria promotes tubule injury and dysfunction, we hypothesized that the proteinuria present in PE could promote the loss of these components into the urine. Twenty preeclamptic patients and ten normal pregnant women with a gestational age greater than 20 weeks composed three groups: NC, normotensive control pregnant patients; PE, non-proteinuric preeclamptic patients; and PPE, preeclamptic patients with proteinuria. When proteinuria was absent, preeclampsia was diagnosed accordingly to the American College of Obstetricians and Gynecologists' (ACOG) guideline. The presence of 24-hour proteinuria equal to or greater than 300 mg was considered to form the PPE group. Urinary cubilin, megalin, and DBP were measured by ELISA and normalized by urinary creatinine. Regarding gestational age, there was no difference between the groups. NC group had arterial pressure within normal values, whereas PE and PPE groups had a significant increase (p < 0.01). As expected, PPE group presented elevated ACR (p < 0.05), accompanied by large amounts of cubilin and DBP in the urine (p < 0.05 vs. NC and PE). No difference was found in urinary megalin. PPE patients showed more chance of shedding cubilin into the urine compared to non-proteinuric patients (odds ratio 12.7 (1.2-136.3). In conclusion, this study further tightens the relationship between PE and vitamin D3 deficiency, since proteinuria present in PE induces the loss of molecules responsible for renal tubular vitamin D3 reabsorption for subsequent activation. Combined with other factors, the proteinuria may intensify vitamin D3 deficiency in PE.
Assuntos
Pré-Eclâmpsia/patologia , Pré-Eclâmpsia/urina , Receptores de Superfície Celular/metabolismo , Proteína de Ligação a Vitamina D/urina , Adolescente , Adulto , Feminino , Idade Gestacional , Humanos , Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Razão de Chances , Gravidez , Adulto JovemRESUMO
Glycerol injection in rats can lead to rhabdomyolysis, with the release of the intracellular muscle content to the extracellular compartment and acute kidney injury (AKI). Oxidative stress and the inflammatory processes contribute to the disturbances in renal function and structure observed in this model. This study evaluated the effect of calcitriol administration in AKI induced by rhabdomyolysis and its relationship with oxidative damage and inflammatory process. Male Wistar Hannover rats were treated with calcitriol (6 ng/day) or vehicle (0.9% NaCl) for 7 days and were injected with 50% glycerol or saline 3 days after the beginning of calcitriol or saline administration. Four days after glycerol or saline injection, urine, plasma and renal tissue samples were collected for renal function and structural analysis. The oxidative stress and the inflammatory processes were also evaluated. Glycerol-injected rats presented increased sodium fractional excretion and decreased glomerular filtration rates. These alterations were associated with tubular injury in the renal cortex. These animals also presented increased oxidative damage, apoptosis, inflammation, higher urinary excretion of vitamin D-binding protein and decreased cubilin expression in renal tissue. All these alterations were less intense in calcitriol-treated animals. This effect was associated with decreases in oxidative damage and inflammation.
Assuntos
Injúria Renal Aguda/tratamento farmacológico , Injúria Renal Aguda/etiologia , Calcitriol/uso terapêutico , Glicerol/farmacologia , Substâncias Protetoras/uso terapêutico , Rabdomiólise/induzido quimicamente , Rabdomiólise/complicações , Injúria Renal Aguda/sangue , Injúria Renal Aguda/urina , Animais , Apoptose/efeitos dos fármacos , Calcitriol/farmacologia , Cálcio/sangue , Creatina Quinase/sangue , Taxa de Filtração Glomerular/efeitos dos fármacos , Inflamação/tratamento farmacológico , Testes de Função Renal , Masculino , Estresse Oxidativo/efeitos dos fármacos , Substâncias Protetoras/farmacologia , Ratos , Ratos Wistar , Proteína de Ligação a Vitamina D/urinaRESUMO
Proteinuria is a marker and mediator of chronic kidney disease (CKD). In clinical practice, the urinary protein-to-creatinine ratio (UP/C) is of limited usefulness, because it indicates only the magnitude of proteinuria and not the origin of the loss (glomerular or tubular). The complete assessment of proteinuria includes quantitative and qualitative evaluations, both of which are required in order to optimize the therapy. In addition to measuring the UP/C, we performed SDS-PAGE and western blotting to determine the expression of albumin, vitamin D-binding protein (VDBP), retinol-binding protein (RBP), and Tamm-Horsfall protein (THP) in urine samples of 49 dogs: healthy (control) dogs (n = 9); and dogs with CKD (n = 40), stratified by stage. In the dogs with stage 3 or 4 CKD, there was a predominance of tubular proteins. Neither VDBP nor RBP was observed in the urine of the control dogs. Among the dogs with stage 1 or 2 CKD, VDBP and RBP were detected in those without proteinuria or with borderline proteinuria. The expression of urinary albumin was significantly higher in the stage 4 group than in any other group (P ≤ 0.01). In the stage 4 group, urinary THP was either undetectable or lower than in the control group (P ≤ 0.01). In conclusion, urinary VDBP and RBP might act as early markers of kidney injury, and a decrease in urinary THP could be an indicator of CKD progression.