Filtrado glomerular y enfermedad cardiovascular en hipertensos / Glomerular filtration and cardiovascular disease in hypertensive patients

Introducción: La enfermedad renal crónica expresada por un filtrado glomerular disminuido se asocia a un mayor riesgo de enfermedad cardiovascular y a mayor progresión del daño renal. Es muy recomendable como método disponible y económico para evaluar el riesgo cardiovascular en hipertensos. Objetivo: Evaluar el daño renal y la enfermedad cardiovascular en hipertensos del Policlínico Managua. Método: Se estudiaron 1037 pacientes hipertensos. Se calculó el filtrado glomerular según el Modification Diet Renal Disease Study. Se estudiaron variables demográficas, factores de riesgo vascular y presencia de enfermedad cardiovascular. Se definió 60 mil/min/1,73m2 para el filtrado glomerular disminuido. Resultados: De los pacientes estudiados, 28,5 por ciento presentaron filtrado glomerular disminuido, mostrando mayor prevalencia de enfermedad cardiovascular que aquellos sin daño renal (53,4 por ciento vs 33,9 por ciento; OR 2,19 IC 95 por ciento 1,51-2,82; p ; 0,001). Conclusiones: Este estudio muestra que la enfermedad renal crónica se asocia a mayor prevalencia de enfermedad cardiovascular, siendo un factor de riesgo cardiovascular mayor(AU)

Introduction: Chronic kidney disease expressed by decreased glomerular filtration rate is associated with high risk of cardiovascular disease and great progression of kidney damage. This filtration is highly recommended as an available and inexpensive method to assess cardiovascular risk in hypertensive patients. Objective: To assess kidney damage and cardiovascular disease in hypertensive patients at Managua Polyclinic. Method: This research included 1037 hypertensive patients. Glomerular filtration was calculated according to the Modification Diet Renal Disease Study. Demographic variables, vascular risk factors, and the presence of cardiovascular disease were studied. The decreased glomerular filtration was defined for ;60 thousand/min/1.73m2. Results: 28.5 percent of the studied patients showed decreased glomerular filtration, higher prevalence of cardiovascular disease than those without kidney damage (53.4 percent ;vs. 33.9 percent; OR 2.19 95 percent CI 1.51-2, 82; p ;0.001). Conclusions: This study showed that chronic kidney disease is associated with high prevalence of cardiovascular disease, which establishes higher cardiovascular risk factor(AU)

Different sample preparation methods for glomerular morphological evaluation: to coat or not to coat? / Diferentes métodos de preparación de muestras para la evaluación morfológica glomerular ¿recubrir o no recubrir?

The renal glomerulus is coated by fenestrated endothelial cells and externally covered by specialized epithelial cells, known as podocytes. Scanning electron microscopy becomes an important and effective tool for its studies. Normally, samples destined for scanning microscopy are covered with a thin metallic layer. However, this step can be dispensed for some analyzes. We aimed to compare coated and uncoated samples for evaluation of the glomerular morphology of the Wistar rat kidney. Cortical region of the kidney of the 5month-old male Wistar rats were used. The fragments followed the routine procedure for scanning electron microscopy processing. Half of 10 fragments were coated with palladium gold and the remaining were not coated. Auriga Compact FIB - SEM scanning electron microscope was used to observe the samples. Different increases and voltages was evaluated. For the uncoated samples, when using voltages of 2 KV (or higher) a great charging was observed, impairing the use of such voltage. Thus, these samples were always observed under voltage of 0.5 KV. On the other hand, in the coated samples, the use of 2 KV was adequate. Almost as a consequence, in the coated samples, the podocyte structures were better characterized, generating better images. Inversely, in the uncoated samples, it was possible to visualize the desired structures and to detect the morphological characteristics of these. The results showed that it is possible to use kidney samples without previous coating to evaluate the glomerular morphology at the ultrastructural level, serving as a tool in the study of pathologies.

El glomérulo renal está recubierto por células endoteliales fenestradas y cubierto externamente por células epiteliales especializadas, conocidas como podocitos. La microscopía electrónica de barrido se convierte en una herramienta importante y efectiva para sus estudios. Normalmente, las muestras destinadas a microscopía de barrido se cubren con una capa metálica delgada. Sin embargo, este paso se puede dispensar para algunos análisis. El objetivo fue comparar muestras recubiertas y no recubiertas para evaluar la morfología glomerular del riñón de rata Wistar. Se utilizó la región cortical del riñón de ratas Wistar macho de 5 meses de edad. Se realizó el procedimiento de rutina para el procesamiento de microscopía electrónica de barrido. La mitad de 10 fragmentos se recubrieron con oro paladio y los restantes no se recubrieron. Se utilizó un microscopio electrónico de barrido SEM Auriga Compact FIB para observar las muestras. Se evaluaron diferentes aumentos y voltajes. Para las muestras no recubiertas, al usar voltajes de 2 KV (o más) se observó una gran carga, impidiendo el uso de dicho voltaje. Por lo tanto, estas muestras siempre se observaron a bajo voltaje de 0,5 KV. Por otro lado, en las muestras recubiertas, el uso de 2 KV fue adecuado. Como consecuencia, en las muestras recubiertas, las estructuras de los podocitos se caracterizaron mejor, generando mejores imágenes. Inversamente, en las muestras no recubiertas, fue posible visualizar las estructuras deseadas y detectar las características morfológicas de éstas. Los resultados mostraron que es posible utilizar muestras de riñón sin recubrimiento previo para evaluar la morfología glomerular a nivel ultraestructural, que sirve como una herramienta en el estudio de patologías.

Interferencia por iopamidol en el proteinograma por elecroforesis capilar y su relación con la función renal / Iopamidol interference in protein separation by capillary electrophoresis and its connection to renal function

Introducción: Las interferencias en el proteinograma electroforético por electroforesis capilar incluyen la aparición de picos con concentraciones y movilidades electroforéticas, que podrían simular la presencia de un componente monoclonal. Objetivos: Ante la aparición de un pico adicional con movilidad intera2-ß por electroforesis capilar (Minicap®-Sebia), el objetivo fue identificar el interferente y evaluar su relación con la funcionalidad renal. Material y métodos: Se estudiaron muestras de suero que presentaron dicha interferencia en un período de un año mediante proteinograma en soporte sólido, electroinmunofijación e inmunoelectroforesis. Se adicionó in vitro el probable interferente para confirmar su movilidad electroforética. Se evaluó el impacto de la corrección de la interferencia con la herramienta "eliminación de artefactos" (Phoresis®-Sebia) y la correlación de la concentración del pico a línea de base del interferente con la estimación de la tasa de filtrado glomerular (CKD- EPI). Resultados: La integración a la línea de base de los picos fue de 0,07-0,36 g/dL. No se observaron particularidades al realizar los estudios complementarios. Se evidenció, en todos los casos, la administración de iopamidol como medio de contraste, confirmándose su movilidad electroforética por su adición in vitro. Mediante la herramienta "eliminación de artefactos" se recuperaron los niveles basales de las fracciones. Se demostró la existencia de una correlación entre la concentración del pico a línea de base del interferente y la estimación de la tasa de filtración glomerular por CKD-EPI (r=-0.534, p<0.0001). Conclusiones: Se identificó al interferente como Iopamidol y se demostró su relación con la disminución de la tasa de filtración glomerular

Introduction: Interferences in the electrophoretic proteinogram by capillary electrophoresis include the appearance of peaks with concentrations and electrophoretic mobilities, which could simulate the presence of a monoclonal component. Objectives: In the light of an additional peak with interα2-ß mobility by capillary electrophoresis (MINICAP®-Sebia), the aim was to identify the interferent and evaluate its connection to renal functionality. Methods: Serum samples that presented this interference over a period of one year were studied by proteinogram on solid support, electroimmunofixation and immunoelectrophoresis. The probable interferent was added in vitro to confirm its electrophoretic mobility. The impact of the interference correction with the "artifact removal" tool (Phoresis®-Sebia) and the correlation of the baseline peak concentration of the interferent with the estimation of the glomerular filtration rate (CKD-EPI) were evaluated. Results: The integration to the baseline of the peaks was 0.07-0.36 g/dL. No particularities were observed when performing the complementary studies. In all cases, the administration of Iopamidol as a contrast medium was demonstrated, confirming its electrophoretic mobility due to its in vitro addition. Using the "artifact removal" tool, the basal levels of the fractions were recovered. The existence of a correlation between the concentration of the baseline peak of the interferent and the estimation of the glomerular filtration rate by CKD-EPI was shown (r=-0.534, p <0.0001). Conclusions: The interferent was identified as Iopamidol and its connection to the decrease in the glomerular filtration rate was demonstrated

Genetic Basis of Steroid Resistant Nephrotic Syndrome

Steroid-resistant nephrotic syndrome (SRNS) has long been a challenge for clinicians due to its poor responsiveness to immunosuppressants, and rapid progression to end-stage renal disease. Identifying a monogenic cause for SRNS may lead to a better understanding of podocyte structure and function in the glomerular filtration barrier. This review focuses on genes associated with slit diaphragm, actin cytoskeleton, transcription factors, nucleus, glomerular basement membrane, mitochondria, and other proteins that affect podocyte biology.

Valor pronóstico de la función renal a corto plazo en pacientes con infarto agudo de miocardio / Short-term prognostic value of renal function in patients with acute myocardial infarction

Resumen Introducción: El infarto agudo de miocardio es una de las primeras causas de muerte en Cuba y el mundo. En la actualidad cerca de un 20 a 30% de los pacientes con enfermedad coronaria, tienen insuficiencia renal. Objetivo: Determinar la asociación entre insuficiencia renal en el momento del ingreso y la mortalidad a corto plazo en los pacientes con infarto agudo de miocardio. Método: Se analizaron 284 pacientes consecutivos con diagnóstico de infarto agudo de miocardio ingresados en la Unidad de Cuidados Intensivos (UCI) del Hospital Universitario "Dr. Miguel Enríquez", entre el 1(. de enero 2015 y el 1(. de diciembre de 2016. Se determinó la creatinina, la tasa de filtrado glomerular estimado y las escalas de pronóstico cardiovascular en el momento del ingreso. Mediante regresión logística se evaluó la capacidad predictiva de muerte a corto plazo de la función renal. Resultados: 26 pacientes fallecieron en la UCI (9,2%). El valor de la creatinina sérica fue superior, en tanto que las tasas de filtrado glomerular fueron inferiores (p < 0,0001) en el grupo de pacientes que falleció respecto a los supervivientes. Todas las variables de función renal y las de pronóstico cardiovascular se asociaron con la mortalidad; al comparar ambas, se obtuvo una mejor discriminación con las primeras en relación a las segundas. Conclusiones: La valoración de la función renal mediante la determinación de la creatinina y la estimación del filtrado glomerular, proporciona información útil y muy valiosa para la evaluación inicial de los pacientes con infarto agudo de miocardio.

Abstract Introduction: Acute myocardial infarction is one of the primary causes of death in Cuba, and the world. Currently, around 20% to 30% of patients with coronary disease have renal failure. Objective: To determine the relationship between renal failure at the time of admission and the short-term mortality in patients with acute myocardial infarction. Material and methods: An analysis was made on a total of 284 consecutive patients with a diagnosis of acute myocardial infarction admitted into the Intensive Care Unit (ICU) of the "Dr. Miguel Enríquez" University Hospital between 1 January 2015 and 1 December 2016. The creatinine and the calculated glomerular filtration rate were determined, as well as the scores on the cardiovascular prognostic scales, at the time of admission. The predictive value of the renal function for short-term death was evaluated using logistic regression. Results: A total of 26 (9.2%) patients died in the ICU. The serum creatinine was higher and the glomerular filtration rates were lower (P < .001) in the patient group that died compared to the survivors. All the renal function variables and the cardiac prognostic scores were associated with mortality. A better discrimination was obtained with the renal function variables compared to the cardiovascular ones. Conclusions: The assessment of renal function using the serum creatinine level and the calculated glomerular filtration rate provide very useful and valuable information for the initial evaluation of patients with acute myocardial infarction.

Interleukin-13 Increases Podocyte Apoptosis in Cultured Human Podocytes

PURPOSE: Podocytes are important architectures that maintain the crucial roles of glomerular filtration barrier functions. Despite this structural importance, however, the mechanisms of the changes in podocytes that can be an important pathogenesis of minimal change nephrotic syndrome (MCNS) are not clear yet. The aim of this study was to investigate whether apoptosis is induced by interleukin (IL)-13 in cultured human podocytes. METHODS: Human podocytes were treated with different IL-13 doses and apoptotic cells were analyzed using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL assay) and fluorescence-activated cell sorting (FACS). RESULTS: The IL-13 increased the number of TUNEL-positive cells in a dose-dependent manner at 6 and 18 hours (P<0.05 and P<0.05, respectively). The apoptosis rate was appeared to be increased slightly in the IL-13-stimulated podocytes (8.63%, 13.02%, and 14.46%; 3, 10 and 30 ng/mL, respectively) than in the control cells (7.66%) at 12 hours by FACS assay. CONCLUSION: Our study revealed that IL-13 expression may increase podocyte apoptosis. Blocking the IL-13 signal pathway can potentially play an important role in regulating the apoptosis of podocytes.

Clinical and nutritional factors associated with dialysis initiation and mortality in chronic kidney disease

BACKGROUND: Chronic kidney disease is worldwide recognized as a public health problem due to high rates of morbidity and mortality. At the end stage of the disease, which the glomerular filtration rate is equal or less than15 ml/min/1.73 m2, dialysis initiation is usually indicated. In the absence of a consensus on the best time of beginning, the aim of this study was to identify clinical and nutritional factors associated with clinical outcomes with the start of dialysis and death. METHODS: In a prospective cohort of 82 patients, clinical (underlying renal disease, renal survival time, systolic and diastolic blood pressure, estimated glomerular filtration rate) and nutritional data (protein intake, anthropometry, bioelectrical impedance test, and strength handgrip) were collected. We used mean and standard deviation ormedian and association of the variables with the outcome entry into dialysis or death, and a Cox regression model was applied. Statistical significance wasp< 0.05.RESULTS: Fifty-eight patients were included in group 1­G1 (without dialysis)­and 24 patients in group 2­G2(dialysis). The groups were different in blood urea nitrogen (p= <0.001), serum creatinine (p= 0.003), estimated glomerular filtration rate (p= 0.002), and serum phosphorus (p= 0.002). After multivariate analysis, only serumalbumin (HR 0.342,p= 0.004) and glomerular filtration rate (HR 0.001,p= 0.001) were associated with entry into dialysis and death. CONCLUSIONS: We concluded that lower levels of serum albumin and glomerular filtration rate values are associated with entry into dialysis or death.

Urine synaptopodin excretion is an important marker of glomerular disease progression

BACKGROUND/AIMS: Podocytes play an important role in maintaining the glomerular filtration barrier and in formation of the slit diaphragm. Podocyte loss is associated with chronic kidney disease progression, but it is not clear whether urinary podocyte proteins in urine reflect the clinical extent of glomerular damage. We investigated the correlation between the amounts of urinary podocyte proteins and renal function and albuminuria. METHODS: The study enrolled 33 patients with diabetic kidney disease or glomerular disease and measured urinary podocytes proteins using Western blotting. Urinary podocyte proteins were measured according to the density of the bands on Western blotting. We measured serum creatinine and the spot urine albumin/creatinine ratio as markers of renal damage, and compared the correlation of urinary podocyte protein in the glomerular disease patients. RESULTS: The mean patient age was 49.3 ± 16.5 years, the mean serum creatinine level was 2.30 ± 1.76 mg/dL, and the mean albumin/creatinine ratio was 4.85 ± 3.52. Among the podocyte proteins, urine synaptopodin showed strong correlation with serum creatinine by multivariate regression analysis (p < 0.001) and showed linear correlation (r = 0.429, p < 0.01). Urine podocyte proteins were increased in patients with diabetes, and synaptopodin showed the greatest significant difference (7.68 ± 5.61 vs. 2.56 ± 3.11, p < 0.001), but this might be associated with renal impairment. The urine albumin excretion did not differ between the diabetics and non-diabetics (p = 0.73). CONCLUSIONS: Urine synaptopodin is associated with serum creatinine elevation in the patients with glomerulonephritis including diabetic kidney disease regardless of urine albumin excretion. We suggest that the urine synaptopodin level can predict glomerular damage independently of the urine albumin excretion.

Pathogenesis of minimal change nephrotic syndrome: an immunological concept / 소아과

Idiopathic nephrotic syndrome (INS) in children is characterized by massive proteinuria and hypoalbuminemia. Minimal change nephrotic syndrome (MCNS) is the most common form of INS in children. The pathogenesis of MCNS still remains unclear, however, several hypotheses have been recently proposed. For several decades, MCNS has been considered a T-cell disorder, which causes the impairment of the glomerular filtration barrier with the release of different circulating factors. Increased levels of several cytokines are also suggested. Recently, a "two-hit" theory was proposed that included the induction of CD80 (B7-1) and regulatory T-cell (Treg) dysfunction, with or without impaired autoregulatory functions of the podocyte. In contrast to the well-established involvement of T cells, the role of B cells has not been clearly identified. However, B-cell biology has recently gained more attention, because rituximab (a monoclonal antibody directed against CD20-bearing cells) demonstrated a very good therapeutic response in the treatment of childhood and adult MCNS. Here, we discuss recent insights into the pathogenesis of MCNS in children.

GLCCI1 is a novel component associated with the PI3K signaling pathway in podocyte foot processes

Podocyte foot processes are interdigitated to form the slit diaphragm and are crucial for the glomerular filtration barrier. Glucocorticoid-induced transcript 1 (GLCCI1) is transcriptionally regulated, but its signaling pathway in podocytes is unknown. The main objective of this study was to investigate the regulation of podocyte foot process proteins and to investigate the role of GLCCI1 in the phosphoinositide 3-kinase (PI3K) pathway using high glucose-induced podocytes and streptozotocin-induced diabetic rats. In podocytes and rat kidneys, GLCCI1 was found to be highly specific for the glomerulus and podocyte foot processes similar to other podocyte-specific proteins (nephrin, podocin, synatopodin and podocalyxin) based on reverse transcription-PCR, western blotting, immunofluorescence and immunoelectron microscopy analyses. In addition, the decrease in the GLCCI1 expression level under hyperglycemic conditions was restored by treatment with a PI3K inhibitor (wortmannin). Immunofluorescence analysis confirmed that GLCCI1 colocalized with nephrin and synaptopodin both in vivo and in vitro. Finally, immunoelectron microscopy data from streptozotocin-induced diabetic rats showed that GLCCI1 also localized in podocyte foot processes. Hence, GLCCI1 is a component of podocyte foot processes, and its expression appears to be regulated via the PI3K pathway.

Insuficiencia renal aguda en el paciente adulto criticamente enfermo. Puesta al día en medicina intensiva. / Acute renal failure in a critically ill adult patient. Update in intensive medicine

La insuficiencia renal aguda (IRA) es un síndrome que se caracteriza por un rápido descenso de la filtración glomerular que se produce en horas o semanas y como consecuencia, determina la retención de productos nitrogenados en sangre. En Terapia Intensiva y Nefrología, la noción IRA se relaciona con disfunción orgánica grave y se ha reconocido la importancia de las disminuciones moderadas de la función renal como predictor independiente de morbimortalidad. La mortalidad en esta entidad no se ha modificado en los últimos 50 años, aunque si hubo un cambio en el patrón epidemiológico. Los objetivos de la presente revisión fueron hacer una puesta al día en el diagnóstico y tratamiento de la insuficiencia renal aguda en pacientes críticos, homogeneizar la metodología de trabajo en las Unidades de Terapia Intensiva y Cuidados Críticos, y desarrollar un algoritmo de diagnóstico y tratamiento para estos pacientes, en los que la evaluación de la función renal presenta particularidades que los diferencian del paciente ambulatorio o crónico. Como resultado de nuestro trabajo pudimos actualizar las formas clásicas de tratamiento y nos atrevemos a proponer algunas estrategias para identificar la capacidad de respuesta del paciente al aporte de fluidos en función de parámetros estáticos y dinámicos, valorables fácilmente en la cama del paciente. Finalmente desarrollamos un algoritmo de diagnóstico y tratamiento para facilitar la tarea de los médicos que afronten este síndrome a la vez tan complejo y desafiante. Creemos que esta herramienta puede contribuir a mejorar los resultados y fundamentalmente a homogeneizar la práctica clínica.

Acute renal failure (ARF) is a syndrome characterized by a rapid decrease in the glomerular filtration rate produced within hours or weeks and, as a consequence, it determines nitrogen retention in the blood. At Intensive Care and Nephrology, the notion of ARF is related to serious organic dysfunction and the importance of moderate decreases in renal function as an independent predictor of morbidity and mortality has been recognized. Mortality in such cases has not been modified in the last 50 years, although there was a change in the epidemiologic pattern. The aims of this review are to update acute renal failure diagnosis and treatment in critical patients, to homogenize work methodology at UTIs, and to develop a diagnosis and treatment algorithm for these patients, in which the evaluation of renal function presents particular characteristics that differentiate such patients from ambulatory or chronic patients. As a result of our work, we have been able to update classical treatment protocols and we dare propose some strategies in order to identify the patient's response to fluid contribution according to static and dynamic parameters, easily assessed at the patient's bed. Finally, we develop a diagnosis and treatment algorithm in order to help physicians who have to face such a complex and challenging syndrome. We believe that this tool can contribute to improve the results and, mainly, to make clinical practice more homogeneous

Glomerular filtration rate is altered in children with sickle cell disease: a comparison between Hb SS and Hb SC

BACKGROUND Renal failure is common among older patients with sickle cell disease; this is preceded by subclinical glomerular hyperfiltration. Data about renal function of adults with sickle cell disease have been reported, but data on children is scarce, especially when comparing heterozygotic and homozygotic patients. OBJECTIVE The goal of this study was to investigate the glomerular filtration rate of heterozygotic and homozygotic children with sickle cell disease. METHODS The glomerular filtration rate of 11 children with sickle cell disease [7 homozygotic (SS) and 4 heterozygotic (SC)] with a mean age of 11 years (standard deviation: ± 5 years) was evaluated using standard laboratory techniques. Results are presented as descriptive analysis. RESULTS Our results suggest that glomerular hyperfiltration is present in children with sickle cell disease; this is more evident in homozygotic than heterozygotic children. CONCLUSION There is evidence of a need to monitor the renal function of children with sickle cell disease when special attention should be paid to homozygotic patients.

Transforming growth factor-beta and the glomerular filtration barrier

The increasing burden of chronic kidney disease worldwide and recent advancements in the understanding of pathologic events leading to kidney injury have opened up new potential avenues for therapies to further diminish progression of kidney disease by targeting the glomerular filtration barrier and reducing proteinuria. The glomerular filtration barrier is affected by many different metabolic and immune-mediated injuries. Glomerular endothelial cells, the glomerular basement membrane, and podocytes-the three components of the filtration barrier-work together to prevent the loss of protein and at the same time allow passage of water and smaller molecules. Damage to any of the components of the filtration barrier can initiate proteinuria and renal fibrosis. Transforming growth factor-beta (TGF-beta) is a pleiotropic cytokine strongly associated with the fibrogenic response.It has a known role in tubulointerstitial fibrosis. In this review we will highlight what is known about TGF-beta and how it interacts with the components of glomerular filtration barrier and causes loss of function and proteinuria.

Transforming growth factor-beta and the glomerular filtration barrier

The increasing burden of chronic kidney disease worldwide and recent advancements in the understanding of pathologic events leading to kidney injury have opened up new potential avenues for therapies to further diminish progression of kidney disease by targeting the glomerular filtration barrier and reducing proteinuria. The glomerular filtration barrier is affected by many different metabolic and immune-mediated injuries. Glomerular endothelial cells, the glomerular basement membrane, and podocytes-the three components of the filtration barrier-work together to prevent the loss of protein and at the same time allow passage of water and smaller molecules. Damage to any of the components of the filtration barrier can initiate proteinuria and renal fibrosis. Transforming growth factor-beta (TGF-beta) is a pleiotropic cytokine strongly associated with the fibrogenic response.It has a known role in tubulointerstitial fibrosis. In this review we will highlight what is known about TGF-beta and how it interacts with the components of glomerular filtration barrier and causes loss of function and proteinuria.

Current concepts of the podocyte in nephrotic syndrome

Nephrotic syndrome is a disorder of the glomerular filtration barrier, and central to the filtration mechanism of the glomerular filtration barrier is the podocyte. We are starting to better understand how this cell, with its unique architectural features, fulfils its exact filtration properties. The multiprotein complex between adjacent podocyte foot processes, the slit diaphragm, is essential to the control of the actin cytoskeleton and cell morphology. Many of the proteins within the slit diaphragm, including nephrin, podocin, transient receptor potential-6 channel, and alpha-actinin-4, have been identified via genetic studies of inherited nephrotic syndromes. Signaling from slit diaphragm proteins to the actin cytoskeleton is mediated via the Rho GTPases. These are thought to be involved in the control of podocyte motility, which has been postulated as a focus of proteinuric pathways. Nephrotic syndrome is currently treated with immunosuppressive therapy, with significant adverse effects. These therapies may work in nephrotic syndrome due to specific effects on the podocytes. This review aims to describe our current understanding of the cellular pathways and molecules within the podocyte relevant to nephrotic syndrome and its treatment. With our current knowledge of the cellular biology of the podocyte, there is much hope for targeted therapies for nephrotic syndromes.

Angiopoietins in Diabetic Nephropathy / 대한신장학회지

PURPOSE: It has been reported that angiopoietins and Tie-2 receptor play an important role in the maintenance of glomerular filtration barrier in various glomerulonephritis models. We studied the role of angiopoietins on renal injury in diabetes. METHODS: In this study, we examined the changes of angiopoietin-1, angiopoietin-2, Tie-2 receptor, and nephrin expression in the experimental diabetic nephropathy and also determined whether these changes were modified by renoprotective intervention by angiotensin II receptor blocker, alpha-lipoic acid, and peroxisome proliferator activated receptor (PPAR)-agonist. RESULTS: A marked increase in urinary albumin excretion and glomerular volume was observed in diabetic rats. Renal angiopoietin-2 and Tie-2 receptor expression were significantly higher in diabetic rats than in the control groups, with a significant reduction in renal angiopoietin-2 expression, albuminuria, and renal hypertrophy in angiotensin II receptor blocker-treated diabetic rats. And there was a significant reduction in renal Tie-2 expression and renal hypertrophy in alpha-lipoic acid-treated and PPAR-gamma agonist-treated diabetic rats. CONCLUSION: These results demonstrate that the dysregulation of angiopoietins and Tie-2 receptor can lead to renal hypertrophy and albuminuria. Angiotensin II receptor blocker, alpha-lipoic acid, and PPAR-gamma agonist attenuated these changes in angiopoietins and/or Tie-2 expression and prevented the development of albuminuria and renal hypertrophy in vivo.

Effects of Angiotensin II on Glomerular Epithelial Cells Permeability Model; Role of Oxidative Stress / 대한신장학회잡지

BACKGROUND: Glomerular injury induced by angiotensin II (Ang II) may arise from its hemodynamic or non-hemodynamic actions including oxidative stress, or from such effects of Ang II acting in concert. The release of reactive oxygen species from podocytes may play a role in the pathogenesis of glomerular damage and proteinuria. METHODS: To investigate whether Ang II induces oxidative stress in vitro in glomerular epithelial cells (GEpC) and whether such oxidant stress may increase in vitro glomerular permeability model using cultured GEpC, we studied GEpC culture exposed to Ang II and antioxidant, probucol. For oxidative system assay, we measured the production of superoxide anion and hydrogen peroxide and the activity of superoxide dismutase (SOD). Scanning electron microscopy was performed on cells grown for one week on chamber slides. RESULTS: We found that in vitro permeability, which was prevented from probucol, increased significantly in media with 10-4 and 10-5 M of Ang II by 15.9% and 13%, respectively. Administration of the 10-5 M of Ang II significantly increased the superoxide anion productions by 39%, 61% and 30% at 1, 2 and 6 hours exposure time, respectively, compared to those of control and suppressed by probucol to control levels. At high concentration (10-5 M) Ang II suppressed the activity of SOD without affecting the production of hydrogen peroxide on the other hand, at low concentration (less than 10-5 M) Ang II showed reverse results. On ultrastructural examination, we could see the shortened and fused microvilli on GEpC surface by 10-5 M of Ang II, which change could be prevented by probucol. CONCLUSION: We could suggest that Ang II induces the generation of superoxide anion and the suppression of the activity of SOD, and subsequent oxidative stress leading to increase glomerular permeability by disruption of glomerular filtration barrier.

Changes of ZO-1 Expression in Diabetic Rat Glomeruli and Cultured Mouse Podocyte Under High Glucose Conditions and the Effect of Angiotensin II Type 1 Receptor Blocker / 대한신장학회잡지

BACKGROUND: Diabetic nephropathy (DN) is clinically characterized by persistent proteinuria. The underlying pathologic changes responsible for the nephropathy are the loss of size selective and/or charge selective properties of the glomerular filtration barrier. Size selectivity is maintained primarily by the slit diaphragm and ZO-1 is one of the basic components of it. However, the precise role of the ZO-1 in the pathogenesis of the glomerular diseases is not fully understood. We investigated the changes of ZO-1 expression in diabetic glomeruli in vivo, and by high glucose in cultured podocyte in vitro. We also evaluated the effect of angiotensin II type 1 receptor blocker (ARB) on the ZO-1 changes induced by diabetes or high glucose. METHODS: To determine the effect of ARB on podocytes ZO-1 protein and mRNA expression, immortalized mouse podocytes were incubated with RPMI medium containing normal glucose (NG, 5.6 mM) or high glucose (HG, 30 mM) with or without ARB (10-6 M, L-158, 809). For animal studies, rats were injected with diluent (Control, C, n=18) or streptozotocin. The latter were left untreated (DM, n=18) or treated with 1 mg/kg/day ARB (DM+ARB, n=18). Six rats from each group were sacrificed monthly, and Western blot and RT?PCR were performed for ZO-1 with sieved glomeruli. Renal sections were stained for ZO-1 by immunohistochemistry. RESULTS: The ZO-1 mRNA and protein expressions in podocytes exposed to HG conditions were significantly higher than those in podocytes exposed to NG media (p<0.05). ARB treatment inhibited the HG induced increase in ZO-1 mRNA and protein expression by 73% and 64%, respectively (p<0.05). Compared to the C rats (19.8+/-3.2 mg/day), 24 hour urinary protein excretion at 3 month was significantly higher in the DM rats (90.6+/-11.3 mg/day, p< 0.05), and ARB treatment partly reversed the increase in proteinuria in DM rats (51.6+/-6.6 mg/day, p<0.05). Glomerular ZO-1 mRNA and protein expressions were also significantly increased in DM than corresponding C at all duration (p<0.05). ARB treatment for 3 months in DM rats inhibited the increase in ZO-1 mRNA and protein expression by 57.5% and 70.6%, respectively (p<0.05). ARB treatment for 3 months significantly ameliorated increased glomerular ZO-1 expression in DM rats as assessed by immunohistochemistry. CONCLUSION: In conclusion, ZO-1 mRNA and protein expressions were increased in podocytes exposed to HG and in DM glomeruli, and this increment in ZO-1 expression was ameliorated with ARB. Taken together, these data suggest that change of ZO-1 expression in podocytes is implicated in the early changes of diabetic nephropathy and may contribute to the development of proteinuria.

P-Cadherin is Decreased in Glucose-Stimulated Podocytes and in Experimental Diabetic Nephropathy / 대한신장학회잡지

BACKGROUND: Proteinuria is a cardinal feature of glomerular disease including diabetic nephropathy, and glomerular filtration barrier is considered as a filter restricting protein excretion in urine. We tested whether the expression of P-cadherin, a molecule known to be located at the slit diaphragm, was altered by high glucose in cultured podocytes in vitro and by diabetes in vivo. METHODS: In vitro, immortalized mouse podocytes were cultured in media with 5.6 mM glucose (NG), NG+24.4 mM mannitol (NG+M), or 30 mM glucose (HG) for 7 days at 37dgrees C. Cell lysates were used for RT-PCR and Western blot. For animal studies, twelve Sprague-Dawley rats were injected with diluent (Control, C, N=6) or streptozotocin (DM, N=6) intraperitoneally, and were sacrificed after 6 weeks. RT-PCR and Western blot for P-cadherin mRNA and protein expression, respectively, were performed with sieved glomeruli, and immunohistochemistry with renal tissue. RESULTS: HG significantly reduced P-cadherin mRNA and protein expression in cultured podocytes by 47% and 62%, respectively (p<0.05). Twenty-four hour urinary albumin excretion was significantly higher in DM (12.80+/-1.12 mg/day) compared to C rats (3.15+/-0.24 mg/day) (p<0.05). Glomerular P-cadherin mRNA expression was significantly lower in DM than that in C rats (p<0.05). P-cadherin protein expression assessed by Western blot and immunohistochemistry showed a similar pattern. CONCLUSION: Exposure of podocytes to HG in vitro and diabetes in vivo reduced P-cadherin mRNA and protein expression. These findings suggest that the decrease in P-cadherin expression is connected to the early changes of diabetic nephropathy and thus may contribute to the development of proteinuria.

Expression of Nephrin in Puromycin Aminonucleoside Nephrosis in Rat / 대한신장학회잡지

BACKGROUND: Nephrin, a recently identified protein, could be a slit diaphragm component and it has been suggested to play a crucial role in maintaining the glomerular filtration barrier. It has been reported that mutations in the nephrin gene lead to congenital nephrosis. However, the expression of nephrin in acquired glomerular disease has not yet been fully clarified. We induced nephrotic-range proteinuria in experimental animal and performed morphologic analysis with immunoelectron microscopy. This study was designed to examine the expression and distribution of nephrin in acquired glomerular disease and to suggest a role of nephrin in pathogenesis of proteinuria. METHODS: Twenty-three rats were divided into 3 experimental groups and control(n=6). 17 rats of experimental groups had intravenous injection of puromycin aminonucleoside(PAN) singly, and were sacrificed at 1 week(n=5), 2 weeks(n=6) and 3 weeks(n= 6) later. The expression of nephrin was observed by immunoelectron microscopy employing the polyclonal antibody against nephrin and gold particle. For quantifications, the gold particles were counted from photographs. RESULTS: The average length of foot process in 1 week group(2,307+/-524 nm) was far greater than that of control(317+/-45 nm). The average number of total gold particles per unit length(10,000 nm) of the GBM was reduced at 1 week(4.4+/-1.3), compared with control(12.1+/-3.9). Also, the average number of junctional gold particles at 1 week(1.7+/-0.5) was decreased compared with control(6.7+/-2.2). No difference was observed in the number of junctional gold particles per slit diaphragm among groups. But, there were significant differences in the distribution of gold particles among groups. Gold particles were seen more frequently at apical plasma membrane and cytoplasm in 1 week group, whereas those were observed prominently at junctions in control. CONCLUSION: These data show that the expression of nephrin was decreased with effacement of foot process in PAN induced nephrosis rat. However, nephrin was preserved at not-damaged slit diaphragm. And the distribution of nephrin was changed in PAN nephrosis. Further studies for nephrin production and redistribution should be needed to understand pathogenesis of nephrotic syndrome.