RESUMO
This work assessed the time course of water renal management together with aquaporin-2 (AQP2) kidney expression and urinary AQP2 levels (AQP2u) in obstructive nephropathy. Adult male Wistar rats were monitored after 1, 2, and 7 days of bilateral ureteral release (bilateral ureteral obstruction (BUO); BUO-1, BUO-2 and BUO-7). Renal water handling was evaluated using conventional clearance techniques. AQP2 levels were assessed by immunoblotting and immunohistochemical techniques. AQP2 expression in apical membranes was downregulated in BUO-1 rats and upregulated both in BUO-2 and BUO-7 animals. AQP2 protein expression in whole cell lysate fraction from kidney cortex and medulla were significantly decreased in all the experimental groups. Concomitantly, mRNA levels of AQP2 decreased in renal medulla of all groups and in renal cortex from BUO-1; however, in renal cortex from BUO-2 and BUO-7 a recovery and an increase in the level of AQP2 mRNA were, respectively, observed. BUO-7 group showed a significant increase in AQP2u. The alterations observed in apical membranes AQP2 expression could explain, at least in part, the evolution time of water kidney management in the postobstructive phase of BUO. Additionally, the AQP2u increase after 7 days of ureteral release may be postulated as a biomarker of improvement in the kidney function.
Assuntos
Obstrução Ureteral , Animais , Rim , Ratos , Ratos WistarRESUMO
Obstructive renal diseases affect renal function and kidney integrity. Nevertheless, little is known about its systemic or extra-renal effects. The organic anion transporting polypeptide 1 (Oatp1) is a carrier expressed in liver and kidneys. In this study, the hepatic and renal expression of Oatp1 was evaluated in rats with obstructive nephropathy. Moreover, the urinary excretion of Oatp1 (Oatp1u ) was evaluated as a potential biomarker for this pathology. Male Wistar rats with bilateral ureteral obstruction for 5 hours (BUO5), 24 hours (BUO24) or sham operated were used. After 24 hours of ureteral releasing, liver and kidney functional parameters, histopathology, Oatp1 tissular expression and Oatp1u were evaluated. For Oatp1u evaluation two groups were added; BUO1 and BUO2 (1 and 2 hours of ureteral obstruction, respectively). Both liver and kidney functional parameters and histopathological studies showed alterations in BUO5 and BUO24. In hepatic homogenates, Oatp1 significantly decreased in BUO groups and in total liver membranes no modifications were observed. In renal homogenates, Oatp1 significantly decreased in BUO groups, but in apical kidney membranes, its expression was increased. Oatp1u was only detected in BUO groups, even in those (BUO1, BUO2) in which no alterations in the traditional parameters of renal function were observed. Modulations in liver and renal expression of Oatp1 could be an organism strategy to attenuate the effects of the disease and an attempt to maintain the complex organ cross-talk between liver and kidneys. Oatp1u could be a new, early and specific biomarker of obstructive nephropathy.
Assuntos
Obstrução Ureteral , Animais , Rim , Nefropatias , Ratos , Ratos WistarRESUMO
BACKGROUND: This study estimated the prevalence and risk factors for decreased estimated glomerular filtration rate (eGFR) in those without known hypertension, type 2 diabetes mellitus, or heavy proteinuria as a surrogate marker for chronic kidney disease of unknown cause (CKDu) among adults in the North of Peru. METHODS: A cross-sectional study was conducted following the Disadvantaged Populations eGFR Epidemiology (DEGREE) Study protocol. Low eGFR was defined based on a single eGFR ≤60 mL/min/1.7m2 estimated using the CKD-EPI equation. Environmental conditions related to CKDu (i.e., work in agriculture or sugarcane, water source, heat intolerance, and pesticide exposure) were evaluated, in addition to traditional risk factors for CKD (i.e., smoking, heavy drinking, physical activity, hypertension, type 2 diabetes mellitus, urolithiasis, among others). RESULTS: A total of 1514 subjects were included in the study, mean age 45.1 (SD: 16.4), and 55.2% were females. Overall, only 26 cases (1.7%; 95%CI: 1.1-2.5%) had an eGFR < 60 mL/min/1.7m2 compatible with CKD definition; when those with hypertension and type-2 diabetes or heavy proteinuria were excluded, according to the DEGREE protocol, the estimate fell to 0.9% (95%CI: 0.4-1.5%). Low physical activity levels (OR = 1.99; 95%CI: 1.18-3.34), hypertension (OR = 2.07; 1.26-3.41), and urolithiasis (OR = 1.97; 95%CI: 1.18-3.27) were factors associated with low eGFR. CONCLUSIONS: A low population-based prevalence of low eGFR (as a surrogate for CKDu), both in rural and urban settings areas, in the Northern Peru, was found. Low physical activity levels, hypertension and urolithiasis were factors associated with low eGFR. Interventions to prevent CKD cases may be focused on well-known CV risk factors and urolithiasis.
Assuntos
Insuficiência Renal Crônica/diagnóstico , Insuficiência Renal Crônica/epidemiologia , Adulto , Estudos Transversais , Feminino , Taxa de Filtração Glomerular , Humanos , Masculino , Pessoa de Meia-Idade , Peru/epidemiologia , Prevalência , Insuficiência Renal Crônica/fisiopatologia , Fatores de RiscoRESUMO
Obstructive nephropathy favors the progression to chronic kidney disease (CKD), a severe health problem worldwide. The unilateral ureteral obstruction (UUO) model is used to study the development of fibrosis. Impairment of renal mitochondria plays a crucial role in several types of CKD and has been strongly related to fibrosis onset. Nevertheless, in the UUO model, the impairment of mitochondria, their relationship with endoplasmic reticulum (ER) stress induction and the participation of both to induce the fibrotic process remain unclear. In this review, we summarize the current information about mitochondrial bioenergetics, redox dynamics, mitochondrial mass, and biogenesis alterations, as well as the relationship of these mitochondrial alterations with ER stress and their participation in fibrotic processes in UUO models. Early after obstruction, there is metabolic reprogramming related to mitochondrial fatty acid ß-oxidation impairment, triggering lipid deposition, oxidative stress, (calcium) Ca2+ dysregulation, and a reduction in mitochondrial mass and biogenesis. Mitochondria and the ER establish a pathological feedback loop that promotes the impairment of both organelles by ER stress pathways and Ca2+ levels dysregulation. Preserving mitochondrial and ER function can prevent or at least delay the fibrotic process and loss of renal function. However, deeper understanding is still necessary for future clinically-useful therapies.
Assuntos
Fibrose/genética , Mitocôndrias/genética , Insuficiência Renal Crônica/genética , Obstrução Ureteral/genética , Sinalização do Cálcio/genética , Reprogramação Celular/genética , Estresse do Retículo Endoplasmático/genética , Fibrose/metabolismo , Fibrose/patologia , Humanos , Mitocôndrias/patologia , Biogênese de Organelas , Oxirredução , Insuficiência Renal Crônica/metabolismo , Insuficiência Renal Crônica/patologia , Obstrução Ureteral/metabolismo , Obstrução Ureteral/patologiaRESUMO
Ureteral obstruction is a relevant cause of kidney damage. The traditional parameters used in clinical practice for the detection of renal injury are insensitive and non-specific for the diagnosis of obstructive renal disease. The organic anion transporter 5 (Oat5) is a carrier expressed exclusively in the kidney. In this study, the Oat5 urinary excretion (Oat5u ) was evaluated as a potential biomarker of obstructive nephropathy, comparing it with traditional markers of renal function and with neutrophil gelatinase-associated lipocalin in urine (NGALu ), a more recent biomarker of renal pathology. Bilateral ureteral obstruction (BUO) was induced in male Wistar rats, by complete ligation of ureters for 1 hour (BUO1), 2 hours (BUO2), 5 hours (BUO5), or 24 hours (BUO24). After 24 hours of ureteral releasing, urea and creatinine plasma concentrations, creatinine clearance, urinary total proteins, urinary glucose, and alkaline phosphatase activities in urine were evaluated. Oat5 and NGAL levels were assessed in urine samples by immunoblotting. All parameters of renal function were altered in the BUO24 and some also in BUO5, while the Oat5u increased in all of the experimental groups analyzed. After a long time of ureteral obstruction (BUO24), the urinary excretion of Oat5 markedly increased, in parallel with the alteration in the other parameters evaluated. Nevertheless, in BUO1 and BUO2, Oat5u appeared as the only parameter modified. Therefore, Oat5u could be proposed as a novel early biomarker of ureteral obstruction, with the additional potential to inform about the severity of the obstructive injury suffered by the kidney.
Assuntos
Transportadores de Ácidos Dicarboxílicos/urina , Nefropatias/urina , Animais , Biomarcadores/urina , Masculino , Ratos , Ratos WistarRESUMO
Obstructive nephropathy is characterized by alterations in renal function that depends on the degree and type of obstruction. To increase the knowledge about the physiopathological mechanisms involved in the renal damage associated with bilateral ureteral obstruction (BUO), we studied the renal expression and function (as urinary citrate excretion) of sodium-dependent dicarboxylate cotransporter (NaDC1) in rats. In addition, we evaluated the urinary excretion of NaDC1 as a candidate biomarker for this pathology. Male Wistar rats underwent bilateral ureteral obstruction for 1 (BUO1), 2 (BUO2), 5 (BUO5), and 24 (BUO24) h or sham operation. After 24 h of ureteral releasing, traditional parameters of renal function and citrate levels were determined, and NaDC1 levels were evaluated in total renal homogenates, apical plasma membranes, and urine by electrophoresis and Western blotting. Traditional parameters of renal function were only modified in BUO5 and BUO24. The renal expression of NaDC1 was decreased in BUO5 and BUO24, with a concomitant increase in urinary excretion of citrate. Moreover, the urinary excretion of NaDC1 increased after short times of ureteral obstruction (BUO1 and BUO2) and was positively correlated with the time elapsed after obstruction. The results obtained from the renal expression of NaDC1 could explain an adaptive mechanism to prevent the formation of kidney stones by increasing the levels of citrate, a calcium chelator. The urinary excretion of NaDC1 could be postulated as an early biomarker of obstructive nephropathy that also gives information about the duration of the obstruction.
Assuntos
Transportadores de Ácidos Dicarboxílicos/metabolismo , Nefropatias/metabolismo , Rim/metabolismo , Transportadores de Ânions Orgânicos Dependentes de Sódio/metabolismo , Simportadores/metabolismo , Obstrução Uretral/metabolismo , Animais , Biomarcadores/urina , Citratos/urina , Transportadores de Ácidos Dicarboxílicos/genética , Transportadores de Ácidos Dicarboxílicos/urina , Nefropatias/etiologia , Nefropatias/urina , Masculino , Transportadores de Ânions Orgânicos Dependentes de Sódio/genética , Transportadores de Ânions Orgânicos Dependentes de Sódio/urina , Ratos , Ratos Wistar , Simportadores/genética , Simportadores/urina , Obstrução Uretral/complicações , Obstrução Uretral/urinaRESUMO
Lethal ventricular arrhythmias increase in patients with chronic kidney disease that suffer an acute coronary event. Chronic kidney disease induces myocardial remodeling, oxidative stress, and arrhythmogenesis. A manifestation of the relationship between kidney and heart is the concomitant reduction in vitamin D receptor (VDR) and the increase in angiotensin II receptor type 1 (AT1 ). Melatonin has renal and cardiac protective actions. One potential mechanism is the increase in the heat shock protein 70 (Hsp70)-an antioxidant factor. We aim to determine the mechanisms involved in melatonin (Mel) prevention of kidney damage and arrhythmogenic heart remodeling. Unilateral ureteral-obstruction (UUO) and sham-operated rats were treated with either melatonin (4 mg/kg/day) or vehicle for 15 days. Hearts and kidneys from obstructed rats showed a reduction in VDR and Hsp70. Associated with AT1 up-regulation in the kidneys and the heart of UUO rats also increased oxidative stress, fibrosis, apoptosis, mitochondrial edema, and dilated crests. Melatonin prevented these changes and ventricular fibrillation during reperfusion. The action potential lengthened and hyperpolarized in melatonin-treated rats throughout the experiment. We conclude that melatonin prevents renal damage and arrhythmogenic myocardial remodeling during unilateral ureteral obstruction due to a decrease in oxidative stress/fibrosis/apoptosis associated with AT1 reduction and Hsp70-VDR increase.
Assuntos
Proteínas de Choque Térmico HSP70/metabolismo , Melatonina/uso terapêutico , Receptor Tipo 1 de Angiotensina/metabolismo , Receptores de Calcitriol/metabolismo , Taquicardia Ventricular/tratamento farmacológico , Taquicardia Ventricular/metabolismo , Actinas/metabolismo , Animais , Apoptose/efeitos dos fármacos , Fibrose/metabolismo , Proteínas de Choque Térmico HSP70/genética , Marcação In Situ das Extremidades Cortadas , Técnicas In Vitro , Rim/metabolismo , Masculino , Microscopia Eletrônica , Microscopia de Fluorescência , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Miocárdio/metabolismo , NADPH Oxidases/metabolismo , Ratos , Ratos Endogâmicos WKY , Receptor Tipo 1 de Angiotensina/genética , Receptores de Calcitriol/genéticaRESUMO
BACKGROUND: Mechanical stress is a key pathogenic driver of apoptosis in the tubular epithelium in obstructive nephropathy. Heat shock protein 70 (Hsp70) and Wilms' tumor (WT-1) have been proposed to represent linked downstream effectors of the cytoprotective properties of NO. In the present study, we sought to evaluate whether the cytoprotective effects of L-arginine in neonatal obstructive nephropathy may be associated with NO-dependent increases in WT-1 and Hsp70 expression. METHODS: Neonatal Wistar-Kyoto rats were submitted to complete unilateral ureteral obstruction (UUO) and treated thereafter with vehicle, L-NAME or L-arginine by daily gavage for 14 days to block or augment NO levels, respectively. Normal rat kidney epithelial cells by NRK-52E were exposed to mechanical stress in vitro in the presence or absence of L-NAME, L-arginine, sodium nitroprusside (SNP), L-arginine + SNP or L-arginine/L-NAME. Induction of apoptosis and the mRNA expression of WT-1 and Hsp70 genes were assessed. RESULTS: WT-1 and Hsp70 genes expression decreased in the presence of L-NAME and following UUO coincident with increased tubular apoptosis. L-arginine treatment increased NO levels, reduced apoptosis and restored expression levels of WT-1 and Hsp70 to control levels. L-arginine treatment in vitro reduced basal apoptotic rates and prevented apoptosis in response to mechanical strain, an effect enhanced by SNP co-incubation. L-NAME increased apoptosis and prevented the anti-apoptotic action of L-arginine. CONCLUSIONS: L-arginine treatment in experimental neonatal UUO reduces apoptosis coincident with restoration of WT-1 and Hsp70 expression levels and directly inhibits mechanical strain-induced apoptosis in an NO-dependent manner in vitro. This potentially implicates an NO-Hsp70-WT-1 axis in the cytoprotective effects of L-arginine.
Assuntos
Arginina/farmacologia , Proteínas de Choque Térmico HSP70/metabolismo , Nefropatias/tratamento farmacológico , NG-Nitroarginina Metil Éster/farmacologia , Óxido Nítrico/metabolismo , Obstrução Ureteral/tratamento farmacológico , Proteínas WT1/metabolismo , Animais , Apoptose/efeitos dos fármacos , Células Cultivadas , Citoproteção , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/fisiologia , Fibrose , Expressão Gênica/efeitos dos fármacos , Proteínas de Choque Térmico HSP70/genética , Córtex Renal/patologia , Nefropatias/etiologia , Nefropatias/patologia , Nefropatias/fisiopatologia , Túbulos Renais/patologia , Masculino , Nitroprussiato/farmacologia , Ratos , Ratos Endogâmicos WKY , Estresse Mecânico , Obstrução Ureteral/complicações , Obstrução Ureteral/fisiopatologia , Proteínas WT1/genéticaRESUMO
Urinary heat shock protein 70 (Hsp70) is rapidly increased in patients with clinical acute kidney injury, indicating that it constitutes a component of the endogenous stress response to renal injury. Moreover, experimental models have demonstrated that Hsp70 activation is associated with the cytoprotective actions of several drugs following obstruction, including nitric oxide (NO) donors, geranylgeranylacetone, vitamin D, and rosuvastatin. Discrete and synergistic effects of the biological activities of Hsp70 may explain its cytoprotective role in obstructive nephropathy. Basic studies point to a combination of effects including inhibition of apoptosis and inflammation, repair of damaged proteins, prevention of unfolded protein aggregation, targeting of damaged protein for degradation, and cytoskeletal stabilization as primary effectors of Hsp70 action. This review summarizes our understanding of how the biological actions of Hsp70 may affect renal cytoprotection in the context of obstructive injury. The potential of Hsp70 to be of central importance to the mechanism of action of various drugs that modify the genesis of experimental obstructive nephropathy is considered.