Marcadores biológicos para necrose tubular aguda em pacientes com doença glomerular / Biological markers for acute tubular necrosis in patients with glomerular disease

INTRODUCTION: Acute kidney injury (AKI) is a common complication in patients with nephrotic syndrome (NS), and it is reported in 34% of adults with idiopathic nephrotic syndrome. Emergence of AKI in the course of nephrotic syndrome requires a prompt differential diagnosis between acute tubular necrosis (ATN) and proliferative glomerular lesions leading to rapidly progressive glomerulonephritis. Although clinical and conventional laboratory clues can be decisive in many cases, sometimes such distinctions rely on renal biopsy, which is an invasive procedure and is not available in many centers. Several new biomarkers have emerged, increasing the perspective on early diagnosis and the prognostic prediction of AKI. OBJECTIVES: In this work, we studied the use of tests based on the urinary concentrations of kidney injury molecule-1 (KIM-1)...

INTRODUÇÃO: A lesão renal aguda (LRA) é uma complicação frequente em pacientes com glomerulopatias, acomentendo até 34% dos adultos com síndrome nefrótica (SNO) idiopática. O diagnóstico diferencial de necrose tubular aguda (NTA) de glomeulonefrite proliferativa ou crescêntica em pacientes com SNO e LRA é fundamental, visto que a NTA pode mimetizar quadro de glomerulonefrite rapidamente progressiva. Dados clínicos e laboratoriais podem ser úteis no diagnóstico diferencial da LRA na SNO, entretanto a distinção entre NTA e glomerulonefrite proliferativa ou crescêntica é feito pela biópsia renal, procedimento invasivo e que não está disponível amplamente. Novos biomarcadores para diagnóstico precoce e preditores diagnósticos na LRA têm sido identificados. OBJETIVOS: Neste trabalho nós avaliamos o uso de testes baseados nas concentrações urinárias de kidney injury molecule-1 (KIM-1)...

Marcadores de necrose tubular aguda e lesão inflamatória glomerular no sedimento urinária de pacientes com síndrome / Acute tubular necrosis markers and inflammatory glomerular injury urinary sediment syndrome patients

Necrose tubular aguda (NTA) é a causa mais frequente de lesão renal aguda (LRA) em pacientes hospitalizados. Em pacientes com síndrome nefrótica (SNO), a NTA mimetiza, por vezes, quadro de glomerulonefrite rapidamente progressiva e requer instituição precoce de imunossupressores. A análise do sedimento urinário é uma ferramenta não invasiva, de baixo custo e ampla disponibilidade. O achado de células epiteliais no sedimento urinário de pacientes com LRA foi associado ao diagnóstico de NTA. Entretanto, estudos em pacientes com SNO associada são escassos. Técnicas de diagnóstico utilizando sedimento urinário corado normalmente não são utilizadas nesses casos. Além do mais, o sedimento urinário é uma importante fonte de proteínas; estudos proteômicos do sedimento urinário revelaram importantes frações de proteínas não encontradas em sobrenadante, que pode ser usado como potencial biomarcador de LRA. Nosso objetivo é identificar alterações citológicas e protéicas no sedimento urinário que permitam o diagnóstico diferencial entre NTA ou lesão inflamatória-proliferativa glomerular (INF) em pacientes com SNO. Trata-se de um estudo de corte transversal, onde foram incluídos 32 pacientes: 5 pacientes normais (grupo controle), 10 com NTA, 9 sem NTA e 8 com glomerulonefrites exsudativas. As células do sedimento urinário foram contadas, citocentrifugadas, coradas em hematoxilina/eosina ou Papanicolaou e contadas diferencialmente como pequenas (<30μm de diâmetro), médias (30-48μm)...

Acute tubular necrosis (ATN) is the most frequent cause of acute kidney injury (AKI) in hospitalized patients. In patients with nephrotic syndrome (NS), acute tubular necrosis mimic, sometimes, rapidly progressive glomerulonephritis and requires premature institution of immunosuppressive treatment. The analysis of urinary sediment is a noninvasive tool, low cost and wide availability. The found of epithelial cells in the urinary sediment of patients with AKI was associated to ATN diagnosis. However, studies in patients with AKI in the set of NS are scarce. Diagnostics techniques using stained urinary sediment are not ordinarily used in these cases. Furthermore, urinary sediment is an important source of proteins; proteomic studies revealed important fractions of proteins not found in urinary supernatant that could be used as potential biomarkers for AKI. Our goal is identify cytological alterations and protein in urinary sediment which allow the differential diagnosis between ATN and inflammatory-proliferative glomerular lesion (INF) in patients with NS. This is a cross sectional study, in which 32 patients were included: 5 normal patients (control group), 10 with ATN, 9 without ATN and 8 with exudative glomerulonephritis. The cells of urinary sediment were counted, cytocentrifuged, stained of hematoxylin/eosin or Papanicolaou and differentially counted as small (<30μm of diameter), medium (30-48μm)...

Preconditioning donor with a combination of tacrolimus and rapamacyn to decrease ischaemia-reperfusion injury in a rat syngenic kidney transplantation model.

Reperfusion injury remains one of the major problems in transplantation. Repair from ischaemic acute renal failure (ARF) involves stimulation of tubular epithelial cell proliferation. The aim of this exploratory study was to evaluate the effects of preconditioning donor animals with rapamycin and tacrolimus to prevent ischaemia-reperfusion (I/R) injury. Twelve hours before nephrectomy, the donor animals received immunosuppressive drugs. The animals were divided into four groups, as follows: group 1 control: no treatment; group 2: rapamycin (2 mg/kg); group 3 FK506 (0, 3 mg/kg); and group 4: FK506 (0, 3 mg/kg) plus rapamycin (2 mg/kg). The left kidney was removed and after 3 h of cold ischaemia, the graft was transplanted. Twenty-four hours after transplant, the kidney was recovered for histological analysis and cytokine expression. Preconditioning treatment with rapamycin or tacrolimus significantly reduced blood urea nitrogen and creatinine compared with control [blood urea nitrogen (BUN): P < 0·001 versus control and creatinine: P < 0·001 versus control]. A further decrease was observed when rapamycin was combined with tacrolimus. Acute tubular necrosis was decreased significantly in donors treated with immunosuppressants compared with the control group (P < 0·001 versus control). Moreover, the number of apoptotic nuclei in the control group was higher compared with the treated groups (P < 0·001 versus control). Surprisingly, only rapamycin preconditioning treatment increased anti-apoptotic Bcl2 levels (P < 0·001). Finally, inflammatory cytokines, such as tumour necrosis factor (TNF)-α and interleukin (IL)-6, showed lower levels in the graft of those animals that had been pretreated with rapamycin or tacrolimus. This exploratory study demonstrates that preconditioning donor animals with rapamycin or tacrolimus improves clinical outcomes and reduce necrosis and apoptosis in kidney I/R injury.

Ozone postconditioning in renal ischaemia-reperfusion model. Functional and morphological evidences.

BACKGROUND: Ischaemia-reperfusion is one of the main causes of kidney complications. The most frequent lesion is acute tubular necrosis. Ozone oxidative preconditioning exerts a modulatory effect of redox state of renal cells in models of ischaemia-reperfusion, by stimulating endogenous antioxidant mechanisms. Similar results have been obtained in more recent studies using ischaemic postconditioning. OBJECTIVES: To evaluate the effect of ozone oxidative postconditioning on renal function and morphology in an ischaemia-reperfusion rat model. METHODS: We used forty female Wistar rats weighing between 150g-200g randomly divided into 4 groups (negative control, positive control, oxygen and ozone). The groups: positive control, oxygen and ozone were subjected to 60 minutes of ischaemia and 10 days of reperfusion. During reperfusion, the oxygen group was given 26mg/kg body weight of oxygen, and the ozone group 0.5mg/kg body weight of ozone, rectally. At the end of the experiment urine and blood samples were taken for renal function tests and kidneys were removed for histological study. RESULTS: The ozone group showed no significant differences for filtration fraction and proteinuria compared to the negative control group. The glomerular filtrate rate, renal plasma flow and creatinine showed a slight improvement in comparison with oxygen and positive control groups. The ozone group showed significantly less overall histological damage than the positive control and oxygen groups. CONCLUSIONS: Ozone postconditioning showed to have a protective effect in preserving renal function and morphology.

Effect of fructose-1,6-bisphosphate on the nephrotoxicity induced by cisplatin in rats.

Cisplatin is one of the most active cytotoxic agents in the treatment of cancer, but its clinical use is frequently limited by nephrotoxicity. The study presented here attempted to evaluate the effect of fructose-1,6-bisphosphate in the cisplatin-induced nephrotoxicity in rats. The drugs were administered intraperitoneally as a single dose: sodium chloride 0.9%, cisplatin (6 mg/kg), fructose-1,6-bisphosphate (500 mg/kg), and cisplatin plus fructose-1,6-bisphosphate (6 and 500 mg/kg, respectively). The use of cisplatin resulted in significant elevation of serum creatinine and urea. The group that received cisplatin plus fructose-1,6-bisphosphate presented a significantly lower level of creatinine and urea compared to the cisplatin group. Acute tubular necrosis was demonstrated in the animals that received cisplatin and a less severe one in the cisplatin plus fructose-1,6-bisphosphate group. Fructose-1,6-bisphosphate has a protective effect over renal function and renal parenchyma in a rat experimental model of cisplatin-induced nephrotoxicity. The anti-inflammatory effect of fructose-1,6-bisphosphate confirms its protective effect in cases of cellular injury.

Resveratrol attenuates cisplatin-induced nephrotoxicity in rats.

Cisplatin is an antitumor drug widely used in the treatment of many malignant tumors. However, the most common adverse effect, nephrotoxicity, limits the use of this drug in many cancer patients. Resveratrol is a phytoalexin that presents highly efficient protection in experimental nephrotoxicity models. This study evaluated the effect of resveratrol on cisplatin-induced kidney damage. Male Wistar rats were treated with resveratrol (25 mg/kg b.w., i.p.) before the administration of cisplatin (5 mg/kg b.w., i.p.) and killed 2 or 5 days later. Blood and urine samples were collected and the kidneys were removed. Rats from the cisplatin group showed acute tubular cell necrosis and increased immunostaining for ED1 (macrophages/monocytes) and T-lymphocytes in the renal cortex and outer medulla when compared with the control group. These alterations were less intense in animals pre-treated with resveratrol. Moreover, indicators of renal injury such as increased serum creatinine levels, urinary volume and urinary protein caused by the administration of cisplatin, were also significantly reduced with resveratrol. Increased lipid peroxidation and glutathione depletion in tissue were attenuated by resveratrol. In conclusion, resveratrol attenuated the cisplatin-induced structural and functional renal changes by reducing free radicals and inhibiting inflammatory cell infiltrates.

Attenuation of glycerol-induced acute kidney injury by previous partial hepatectomy: role of hepatocyte growth factor/c-met axis in tubular protection.

BACKGROUND/AIMS: Previous partial hepatectomy (HPTX) can attenuate glycerol-induced acute kidney injury (Gly-AKI). The aim of this study was to explore the pathophysiological mechanisms and the role of hepatocyte growth factor (HGF) in kidney protection. METHODS: Rats were subjected to HPTX 24 h before glycerol administration. Renal function, acute tubular necrosis, apoptosis, leukocyte infiltration, and the expression of HGF, c-met, monocyte chemoattractant protein-1, interleukin-1beta, and heme oxygenase-1 were evaluated 24 h after glycerol injection. The regenerative response was analyzed from 6 to 72 h after glycerol injection (BrdU incorporation). In a separate series of experiments, Gly-AKI+HPTX rats were treated with anti-HGF antibody. RESULTS: Gly-AKI+HPTX rats showed an increased expression of renal HGF and c-met as well as an improved creatinine clearance and reduced acute tubular necrosis and apoptosis, cytokine expression, and leukocyte infiltration. The regenerative response was less intense 24 and 72 h after glycerol administration in this group. The anti-HGF treatment disclosed an important role of HGF in the reduction of tubular injury, particularly apoptosis. Overexpression of heme oxygenase-1 was observed in Gly-AKI+HPTX rats, but was not associated with HPTX-induced renal protection. CONCLUSION: We conclude that Gly-AKI+HPTX rats have a reduced susceptibility to renal injury instead of an increased regenerative response and that endogenous HGF overexpression is responsible for suppression of tubular apoptosis.

[Protective effect of melatonin and sodium thiosulphate on histopathology and ultrastructure of the kidney in rats with acute paraquat poisoning]. / Efecto protector de la melatonina y el tiosulfato de sodio sobre la histopatología y la ultraestructura del riñon en ratas con intoxicación aguda por Paraquat.

Paraquat (PQ) toxicity produces severe injures in many major organs systems, including kidney, developing renal failure with fatal evolution in most of the cases. Several antidotes have been used in the treatment of paraquat intoxication without satisfactory results. The antioxidative effect of melatonin (MLT) and sodium thiosulphate (STS) on kidney in rats with acute intoxication by PQ was studied. Forty male Wistar rats were used, divided in 4 groups of 10 rats each. Group I, control, was injected intraperitoneally (ip) with 1 ml of saline solution; group II, received DL50 of PQ, ip; groups III and IV, DL50 of PQ, and simultaneously the first dose of MLT (15 mg/kg, ip) or STS (1,5 g/kg, i.p.) respectively. Thirty minutes later, groups III and IV received a second similar dose of MLT and TSS. After 24 hours, rats were sacrificed with pentobarbital, and kidneys were extracted for morphological study. Light and electronic microscopy observations showed in group II morphological changes of acute tubular necrosis in proximal tubule in group II, similar findings, with lesser magnitude, were observed in the animals treated with the antidotes, suggesting a partial protection. In conclusion, individual use of MLT and STS at the doses and time used partially prevent damage caused by paraquat to the cell. In consequence, more experiments with these drugs are necessary to considere them as specific treatments in cases of poisoning by paraquat.

Bothrops venom induces direct renal tubular injury: role for lipid peroxidation and prevention by antivenom.

Acute renal failure (ARF) is one of the most serious complications of Bothrops snakebites. Pathogenesis of ARF in snakebite envenomation may involve hemodynamic disturbances, immunologic reactions and direct nephrotoxicity. This study aimed at evaluating Bothrops jararaca venom direct toxicity on isolated rat renal proximal tubules (PT). PT was kept oxygenated and subjected to hypoxia (H, 15 min) and reoxygenation (R, 45 min). Bothropic antivenom effects, role of extracellular calcium and peroxide production were also evaluated. Cell injury was determined by LDH release (%) and peroxide production determined by xylenol-orange method. B. jararaca venom caused tubular injury (LDH 31.6 vs. 17.2%, P <0.05), which was prevented by simultaneous or delayed antivenom administration, but not with low extracellular calcium medium. Venom increased tubules peroxide production: 2.21 vs. 1.27 microM/mg protein (P <0.05) which was also prevented by antivenom administration. Venom toxic concentration did not enhance H/R injury. In contrast, non-toxic venom concentration afforded protection (LDH 41.3 vs. 51.5%, P <0.05). In conclusion, B. jararaca venom caused direct injury to normoxic renal tubules, but not to hypoxic/reoxygenated tubules. Tubular toxicity is independent of extracellular calcium and mediated in part by lipid peroxidation. Venom induced tubular injury was prevented by simultaneous or delayed antivenom administration.

Protección del riñón isquémico en el paciente crítico. Mito y realidad del uso de diuréticos y fármacos vasoactivos / Protection of ischemic kidney in the critically ill patient. Myth and truth of the use of diuretis and vasoactive drugs

La insuficiencia renal aguda (IRA) es uno de los trastornos fisiopatológicos frecuentes en el paciente crítico y a menudo se presenta formando parte del síndrome de disfunción múltiple de órganos. La presencia de IRA aumenta la mortalidad, aunque la causa de muerte no dependa directamente de la insuficiencia renal. Por estas razones, se han hecho múltiples intentos por evitar la aparición de este trastorno, a fin de mejorar la evolución de los pacientes críticos. El patrón patogénico inicial de la IRA en cualquiera de sus formas se caracteriza por un intenso y sostenido aumento de las resistencias vasculares renales, ya sea como consecuencia de cambios en la hemodinamia sistémica o intrarrenal. La modificación de este perfil constituye la base teórica de cualquier estrategia de prevención de la IRA causada por necrosis tubular aguda. En tal sentido, se han ensayado diversos fármacos que han demostrado, a nivel experimental o en sujetos sanos, efectos positivos sobre el flujo sanguíneo renal, la tasa de filtrado glomerular o la eliminación de sodio y agua. Los diuréticos de asa y la dopamina son los fármacos que han generado mayor entusiasmo y un uso muy extendido, sobre todo en las unidades de cuidado intensivo. Lamentablemente, revisiones cuidadosas de los estudios realizados en pacientes en riesgo de IRA o en las etapas tempranas de la misma, no han mostrado evidencia suficiente que sustente el uso de estos fármacos en este contexto y por el contrario, se han demostrado posibles efectos secundarios perjudiciales que los hacen potencialmente riesgosos. El restablecimiento de una adecuada perfusión renal con expansión de volumen y eventualmente noradrenalina en los pacientes sépticos, junto con la restricción de fármacos nefrotóxicos, son las únicas medidas con efectividad demostrada hasta el momento (AU)