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.

Pathology of C3 Glomerulopathy

C3 glomerulopathy is a renal disorder involving dysregulation of alternative pathway complement activation. In most instances, a membranoproliferative pattern of glomerular injury with a prevalence of C3 deposition is observed by immunofluorescence microscopy. Dense deposit disease (DDD) and C3 glomerulonephritis (C3GN) are subclasses of C3 glomerulopathy that are distinguishable by electron microscopy. Highly electron-dense transformation of glomerular basement membrane is characteristic of DDD. C3GN should be differentiated from post-infectious glomerulonephritis and other immune complex-mediated glomerulonephritides showing C3 deposits.

De novo mutations in COL4A5 identified by whole exome sequencing in 2 girls with Alport syndrome in Korea / 소아과

Alport syndrome (ATS) is an inherited glomerular disease caused by mutations in one of the type IV collagen novel chains (α3, α4, and α5). ATS is characterized by persistent microscopic hematuria that starts during infancy, eventually leading to either progressive nephritis or end-stage renal disease. There are 3 known genetic forms of ATS, namely X-linked ATS, autosomal recessive ATS, and autosomal dominant ATS. About 80% of patients with ATS have X-linked ATS, which is caused by mutations in the type IV collagen α5 chain gene, COL4A5. Although an 80% mutation detection rate is observed in men with X-linked ATS, some difficulties do exist in the genetic diagnosis of ATS. Most mutations are point mutations without hotspots in the COL4A3, COL4A4, and COL4A5 genes. Further, there are insufficient data on the detection of COL4A3 and COL4A4 mutations for their comparison between patients with autosomal recessive or dominant ATS. Therefore, diagnosis of ATS in female patients with no apparent family history can be challenging. Therefore, in this study, we used whole-exome sequencing (WES) to identify mutations in type IV collagen in 2 girls with glomerular basement membrane structural changes suspected to be associated with ATS; these patients had no relevant family history. Our results revealed de novo c.4688G>A (p.Arg1563Gln) and c.2714G>A (p.Gly905Asp) mutations in COL4A5. Therefore, we suggest that WES is an effective approach to obtain genetic information in ATS, particularly in female patients without a relevant family history, to detect unexpected DNA variations.

Síndrome de alport: reporte de un caso / Alport syndrome: Case report

El síndrome de Alport (SA) es un conjunto de enfermedades que se caracterizan por una afección hereditaria de la membrana basal glomerular con alteraciones en el colágeno tipo IV que la compone. Se presenta con hematuria micro- o macroscópica; además, suele asociarse a alteraciones auditivas y oculares, y es causa de alrededor de 0.3 a 3% de la enfermedad renal terminal en pediatría.Se reporta el caso de adolescente de 14 años, sexo masculino, que consultó por presentar fiebre, debilidad generalizada y palidez de tres días de evolución. Tenía historia de leucocoria en ojo derecho desde el nacimiento, antecedentes familiares de hematuria (padre y hermano), además hipoacusia en oído derecho. Esto sumado a la lesión ocular antes descrita y a insuficiencia renal crónica se sospechó SA, por lo que se le realizó una audiometría y un ultrasonido (USG) ocular los cuales reportaban una hipoacusia de oído derecho y condensaciones vítreas en ojo derecho respectivamente; dada la hematuria familiar y propia del paciente se realizó el diagnóstico de Síndrome de Alport según los criterios de Flinter...(AU)

Bone mineral density in children with idiopathic nephrotic syndrome / Densidade mineral óssea em crianças com síndrome nefrótica idiopática

Abstract Objectives: To assess bone mineral density (BMD) in children with idiopathic nephrotic syndrome (NS) and normal glomerular filtration rate (GFR). Methods: Cross-sectional case-control study carried out on 50 children: 25 cases of NS (16 steroid-sensitive [SSNS] and nine steroid-resistant [SRNS] under follow up in the pediatric nephrology unit of Menoufia University Hospital, which is tertiary care center, were compared to 25 healthy controls with matched age and sex. All of the participants were subjected to complete history taking, thorough clinical examination, laboratory investigations (serum creatinine, blood urea nitrogen [BUN], phosphorus [P], total and ionized calcium [Ca], parathyroid hormone [PTH], and alkaline phosphatase [ALP]). Bone mineral density was measured at the lumbar spinal region (L2-L4) in patients group using dual-energy X-ray absorptiometry (DXA). Results: Total and ionized Ca were significantly lower while, serum P, ALP, and PTH were higher in SSNS and SRNS cases than the controls. Osteopenia was documented by DXA scan in 11 patients (44%) and osteoporosis in two patients (8%). Fracture risk was mild in six (24%), moderate in two (8%), and marked in three (12%) of patients. Conclusion: Bone mineralization was negatively affected by steroid treatment in children with NS.

Resumo Objetivos: Avaliar a densidade mineral óssea (DMO) em crianças com síndrome nefrótica idiopática (SNI) e com taxa de filtração glomerular (TFG) normal. Métodos: O estudo transversal de caso-controle foi feito com 50 crianças: 25 casos de SNI [16 sensíveis a esteroides (SNSE) e nove resistentes a esteroides (SNRE) com acompanhamento na unidade de nefrologia pediátrica do hospital da Menoufia University, centro de cuidados terciário] foram comparados com 25 controles saudáveis do grupo de controle com idade e sexo equivalentes. Todos os participantes foram submetidos a anamnese completa, exame clínico completo, exames laboratoriais [creatinina sérica, nitrogênio ureico no sangue (BUN), fósforo (P), cálcio (Ca) total e ionizado, paratormônio (PTH) e fosfatase alcalina (ALP)]. A densidade mineral óssea foi mensurada na região da coluna lombar (L2-L4) no grupo de pacientes com a absorciometria por raios X de dupla energia (DXA). Resultados: Os níveis de cálcio total e ionizado eram significativamente menores, ao passo que o fósforo sérico, a FA e o PTH eram maiores em casos de SNSE e SNRE do que nos controles. A osteopenia foi documentada pelo exame DXA em 11 pacientes (44%) e a osteoporose em dois (8%). O risco de fratura era leve em seis (24%), moderado em dois (8%) e acentuado em três (12%). Conclusão: A mineralização dos ossos foi afetada negativamente pelo tratamento com esteroides em crianças com SNI.

Long-term Prognosis of thin Glomerular Basement Membrane Nephropathy in Children: A Retrospective Single Center Study

PURPOSE: Thin glomerular basement membrane nephropathy (TBMN) is, along with the IgA nephropathy, the most common cause of asymptomatic hematuria in Korean children. TBMN is usually a benign renal disease not requiring treatment and is associated with a good prognosis, but some cases hematuria is indicative of a state of progressive renal insufficiency. We aimed to retrospectively evaluate clinical manifestations and renal prognosis of patients with TBMN. METHODS: Among the 428 renal biopsies performed on children at Yeungnam University Hospital between January 2000 and February 2017, 167 patients were diagnosed as having TBMN. We retrospectively investigated 167 pediatric patients and identified 59 children with follow-up duration >3 years. RESULTS: Among 59 patients, there were 33 boys and 26 girls. Mean age of onset of hematuria was 7.18±2.64 years, and mean time from onset of disease until a renal biopsy was performed was 2.48±2.10 years. There were no clinical features or laboratory findings among studied children to indicate decreased renal function during follow-up; however, one case progressed to chronic kidney disease (CKD) due to an unknown cause. There were seven patients among these related a positive family history of hematuria or renal insufficiency. CONCLUSION: Although almost all patients had normal renal functions during follow-up, there were one patient who progressed to CKD and seven patients with family history of hematuria or renal insufficiency. Moreover, four among the 428 patients over 17 years underwent repeat renal biopsies, which showed results different from their earlier biopsies.Thus, large-scales studies may be required to determine long-term prognosis of TBMN in children, and further evaluation for Alport syndrome in TBMN cases is essential.

Long-term Prognosis of thin Glomerular Basement Membrane Nephropathy in Children: A Retrospective Single Center Study

PURPOSE: Thin glomerular basement membrane nephropathy (TBMN) is, along with the IgA nephropathy, the most common cause of asymptomatic hematuria in Korean children. TBMN is usually a benign renal disease not requiring treatment and is associated with a good prognosis, but some cases hematuria is indicative of a state of progressive renal insufficiency. We aimed to retrospectively evaluate clinical manifestations and renal prognosis of patients with TBMN. METHODS: Among the 428 renal biopsies performed on children at Yeungnam University Hospital between January 2000 and February 2017, 167 patients were diagnosed as having TBMN. We retrospectively investigated 167 pediatric patients and identified 59 children with follow-up duration >3 years. RESULTS: Among 59 patients, there were 33 boys and 26 girls. Mean age of onset of hematuria was 7.18±2.64 years, and mean time from onset of disease until a renal biopsy was performed was 2.48±2.10 years. There were no clinical features or laboratory findings among studied children to indicate decreased renal function during follow-up; however, one case progressed to chronic kidney disease (CKD) due to an unknown cause. There were seven patients among these related a positive family history of hematuria or renal insufficiency. CONCLUSION: Although almost all patients had normal renal functions during follow-up, there were one patient who progressed to CKD and seven patients with family history of hematuria or renal insufficiency. Moreover, four among the 428 patients over 17 years underwent repeat renal biopsies, which showed results different from their earlier biopsies.Thus, large-scales studies may be required to determine long-term prognosis of TBMN in children, and further evaluation for Alport syndrome in TBMN cases is essential.

Clinical and pathological features and the misdiagnosis of childhood Alport syndrome: a retrospective analysis of 91 cases / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To explore the clinical and pathological features and the diagnosis of childhood Alport syndrome (AS).</p><p><b>METHODS</b>A retrospective analysis was performed on clinical data of 91 children with AS.</p><p><b>RESULTS</b>Hematuria was observed in all 91 patients, of whom 86 were accompanied with proteinuria. Sixty-one children with X-Linked AS (XL-AS) had positive family history. Renal biopsy was performed on 82 children. Mild to moderate mesangial proliferation was observed in 74 cases. Small amounts of immune complexes deposits in the glomerular mesangial area were observed in 48 cases. Glomerular basement membrane (GBM) attenuation, thickening and layering were observed in 53 cases by electron microscopy (EM). In 63 cases receiving renal tissue type IV collagen α3 and α5 chain immunofluorescence detection, 58 were diagnosed with AS, including 53 cases of XL-AS and 5 cases of autosomal recessive AS. In 91 cases of AS, 58 were diagnosed as AS by renal tissue type IV collagen α3 and α5 chain immunofluorescence, 21 were diagnosed by EM, one was diagnosed by skin biopsy, and 12 were diagnosed by gene detection. Six novel mutations of COL4A5 gene were found. Forty-five cases were misdiagnosed before the diagnosis of AS. Forty-one of the 45 cases received steroids and/or immunosuppressant therapy.</p><p><b>CONCLUSIONS</b>The clinical manifestations and pathological changes are not specific in children with AS, resulting in a higher rate of misdiagnosis. Typical lesions of GBM under EM are only observed in a part of patients. There is a high novel mutation rate of COL4A5 in the detected AS children.</p>

Renoprotective Effect of Gemigliptin, a Dipeptidyl Peptidase-4 Inhibitor, in Streptozotocin-Induced Type 1 Diabetic Mice

BACKGROUND: Dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used in the treatment of patients with type 2 diabetes and have proven protective effects on diabetic kidney disease (DKD). Whether DPP-4 inhibitors have renoprotective effects on insulin-deficient type 1 diabetes has not been comprehensively examined. The aim of this study was to determine whether gemigliptin, a new DPP-4 inhibitor, has renoprotective effects in streptozotocin (STZ)-induced type 1 diabetic mice. METHODS: Diabetes was induced by intraperitoneal administration of a single dose of STZ. Mice with diabetes were treated without or with gemigliptin (300 mg/kg) for 8 weeks. Morphological changes of the glomerular basement membrane (GBM) were observed by electron microscopy and periodic-acid Schiff staining. In addition, we measured blood glucose and urinary albumin excretion and evaluated fibrotic markers using immunohistochemical staining, quantitative reverse transcription polymerase chain reaction analysis, and Western blot analysis. RESULTS: Gemigliptin did not reduce the blood glucose levels of STZ-treated mice. In gemigliptin-treated mice with STZ, a significant reduction in urinary albumin excretion and GBM thickness was observed. Immunohistological examination revealed that gemigliptin attenuated renal fibrosis induced by STZ and decreased extracellular matrix protein levels, including those of type I collagen and fibronectin, and Smad3 phosphorylation. In cultured rat renal cells, gemigliptin inhibited transforming growth factor β-stimulated type I collagen and fibronectin mRNA and protein levels via down-regulation of Smad3 phosphorylation. CONCLUSION: Our data demonstrate that gemigliptin has renoprotective effects on DKD, regardless of its glucose-lowering effect, suggesting that it could be used to prevent DKD, including in patients with type 1 diabetes.

Productos finales de glicación (AGES) y la nefropatía diabética / Glycation end products (AGEs) and diabetic nephropathy

Los productos finales de glicación (AGEs) son un grupo heterogéneo de moléculas generadas por medio de reacciones no enzimáticas de glicación y de oxidación de proteínas, lípidos y ácidos nucleicos. La formación aumentada de AGEs ocurre en condiciones tales como la diabetes mellitus y el envejecimiento. AGEs median sus efectos a través de tres mecanismos principales: 1) entrecruzamiento con proteínas de la matriz extracelular, afectando las propiedades mecánicas de los tejidos, 2) entrecruzamiento con proteínas intracelulares alterando sus funciones fisiológicas y 3) unión a sus receptores de superficie RAGE para inducir múltiples cascadas de señales intracelulares. La acumulación de AGEs en las proteínas tisulares ha sido implicada en las complicaciones vasculares diabéticas, tales como la retinopatía, la nefropatía y la neuropatía. En la nefropatía diabética los AGEs contribuyen al desarrollo y progresión de esta enfermedad renal.

Advanced glycation end products (AGEs) are a heterogenous group of molecules that are generated through nonenzimatic glycation and oxidation of proteins, lipids and nucleic acids. Enhanced formation and accumulation of AGEs has been reported to occur in conditions such as diabetes mellitus as well as in natural aging. AGEs mediate their effects through three main mechanism: 1) cross linking extracellular (matrix) proteins thereby affecting tissue mechanical properties, 2) cross linking intracellular proteins thus altering their physiological functios and 3) binding to their cell surface receptor RAGE to inducing multiple intracellular signalling cascades. The accumulation of AGEs in tissue proteins has been implicated in diabetic vascular complications, such as retinopathy, nephropathy and neuropathy. In the diabetic nephropathy AGEs contribute to the development and progression of this renal disease.

Efficacy and safety of tacrolimus vs. cyclophosphamide for idiopathic membranous nephropathy: A meta-analysis of Chinese adults / 华中科技大学学报（医学）（英德文版）

The efficacy and safety of tacrolimus (TAC) and cyclophosphamide (CTX) in the treatment of idiopathic membranous nephropathy (IMN) were compared in Chinese adult patients using a meta- analysis of the available literatures. Randomized controlled clinical trials (RCTs) of the treatment of primary IMN with TAC or CTX combined with corticosteroids in the English databases PubMed, Embase and Cochrane, as well as Chinese databases, were searched. Qualified studies were subjected to quality assessment and meta-analysis. A total of 8 RCTs, including 359 Chinese patients, were included in the meta-analysis. The complete remission rate and overall remission rate in the TAC treatment group after 6 months of treatment were higher than those in the CTX treatment group. No significant difference in remission rate was found after 12 months of treatment. There was no significant difference in the adverse reaction between the two groups at the 6th or 12th months. TAC-based treatment was associated with a faster response than CTX at the 6th month, but there was no significant difference between the two groups at 12th month in Chinese adults. Further study is needed to evaluate the long-term efficacy and safety of this treatment regimen.

Pathology and Renal Outcome of IgA Nephropathy / 대한내과학회지

BACKGROUND/AIMS: The Oxford classification of immunoglobulin A nephropathy (IgAN) is a pathology-based prognostic classification system. However, further study is needed to determine its validity. We studied the relationships between the Oxford classification and established prognostic factors and renal survival. We also examined associations between electron microscopy findings and these parameters. METHODS: We reviewed and reclassified 213 patients who were diagnosed with IgAN from 1997 to 2007 using the Oxford and World Health Organization (WHO) classification systems. The patients were also categorized by a pathologist using electron microscopy findings, including foot process fusion, glomerular basement membrane thickness, and electron-dense deposits. We examined the correlations between light and electron microscopy data and known prognostic factors (e.g., age, sex, proteinuria, serum creatinine, estimated glomerular filtration rate [eGFR], and blood pressure). The same procedure was applied to renal survival. RESULTS: Patient age increased with the grades of segmental sclerosis (S) and tubular atrophy/interstitial fibrosis (T) (P < 0.05). eGFR decreased significantly with increasing mesangial hypercellularity (M) (p = 0.0034), S (p = 0.0003), endocapillary hypercellularity (E) (p = 0.0411), and T (P < 0.0001). MSET differed significantly by sex (P < 0.0001). The 24-h urine protein/creatinine ratio increased significantly with the degrees of S (p = 0.036), E (p = 0.0155), and T (p = 0.015). The serum creatinine level was significantly higher in patients with T2 than T1 or T0 (P < 0.0001). At the time of biopsy, the degree of tubular atrophy/interstitial fibrosis affected the doubling of serum creatinine or end-stage renal disease. However, the electron microscopy findings did not predict the renal outcome. CONCLUSIONS: Our study suggests that tubular atrophy/interstitial fibrosis is significantly associated with proteinuria and renal progression in IgAN.

Renovascular morphological changes in a rabbit model of hydronephrosis / 华中科技大学学报（医学）（英德文版）

Obstructive nephropathy ultimately leads to end-stage renal failure. Renovascular lesions are involved in various nephropathies, and most renal diseases have an ischemic component that underlies the resulting renal fibrosis. The aim of this study was to investigate whether morphological changes occur in the renal vasculature in hydronephrosis and the possible mechanisms involved. A model of complete unilateral ureteral obstruction (CUUO) was used. Experimental animals were divided into five groups: a normal control group (N) and groups of animals at 1st week (O1), 2nd week (O2), 4th week (O4) and 8th week (O8) after CUUO. Blood pressure was measured, renal arterial trees and glomeruli were assessed quantitatively, and renovascular three-dimensional reconstruction was performed on all groups. Glomerular ultrastructural changes were examined by transmission electron microscopy. The results showed that the systolic blood pressure was significantly increased in the obstructed groups (O1, O2, O4 and O8). Three-dimensional reconstruction showed sparse arterial trees in the O8 group, and a tortuous and sometimes ruptured glomerular basement membrane was found in the O4 and O8 groups. Furthermore, epithelial media thickness and media/lumen ratio were increased, lumen diameters were decreased, and the cross-sectional area of the media was unaltered in the segmental renal artery, interlobar artery and afferent arterioles, respectively. In conclusion, renal arterial trees and glomeruli were dramatically altered following CUUO and the changes may be partially ascribed to vascular remodeling. Elucidation of the molecular mechanisms of renovascular morphological alterations will enable the development of potential therapeutic approaches for hydronephrosis.

Comprehensive approach to diabetic nephropathy

Diabetic nephropathy (DN) is a leading cause of mortality and morbidity in patients with diabetes. This complication reflects a complex pathophysiology, whereby various genetic and environmental factors determine susceptibility and progression to end-stage renal disease. DN should be considered in patients with type 1 diabetes for at least 10 years who have microalbuminuria and diabetic retinopathy, as well as in patients with type 1 or type 2 diabetes with macroalbuminuria in whom other causes for proteinuria are absent. DN may also present as a falling estimated glomerular filtration rate with albuminuria as a minor presenting feature, especially in patients taking renin-angiotensin-aldosterone system inhibitors (RAASi). The pathological characteristic features of disease are three major lesions: diffuse mesangial expansion, diffuse thickened glomerular basement membrane, and hyalinosis of arterioles. Functionally, however, the pathophysiology is reflected in dysfunction of the mesangium, the glomerular capillary wall, the tubulointerstitium, and the vasculature. For all diabetic patients, a comprehensive approach to management including glycemic and hypertensive control with RAASi combined with lipid control, dietary salt restriction, lowering of protein intake, increased physical activity, weight reduction, and smoking cessation can reduce the rate of progression of nephropathy and minimize the risk for cardiovascular events. This review focuses on the latest published data dealing with the mechanisms, diagnosis, and current treatment of DN.

Analysis of ultrastructural glomerular basement membrane lesions and podocytes associated with proteinuria and sclerosis in Osborne-Mendel rats with progressive glomerulonephropathy

The renal glomeruli of 12 male Osborne-Mendel (OM) rats 3 to 24 weeks old were examined by electron microscopy. Effacement of podocyte foot processes (FPs) developed at 3 weeks of age and became progressively worse over time. Loss or dislocation of the slit membrane was also found. Vacuoles and osmiophilic lysosomes appeared in the podocytes starting at 6 weeks of age. Podocyte detachment from the glomerular basement membrane (GBM) was apparent at 18 weeks of age. Laminated GBM was occasionally observed in all animals. These features might lead to the development of spontaneous proteinuria and glomerulosclerosis in OM rats.

Clinical manifestations of IgA nephropathy combined with thin glomerular basement membrane nephropathy in children

BACKGROUND: Immunoglobulin A nephropathy (IgAN) and thin glomerular basement membrane nephropathy (TBMN) are the most common causes of persistent hematuria during childhood. The objective of this study is to determine the difference in clinicl features and laboratory findings between pediatric patients with IgA deposited TBMN and IgAN alone. METHODS: Between January 2000 and March 2009, 95 children were diagnosed with IgAN by renal biopsy. Clinical features and laboratory findings of patients with isolated IgAN and with IgAN plus TBMN were compared; the children diagnosed with IgAN were compared to 127 children who had been diagnosed with TBMN alone during the same period. RESULTS: There were 71 (74.7%) of a total 95 patients that were diagnosed with isolated IgAN (Group 1); in 24 (25.3%) of the 95 patients IgAN was combined with TBMN (Group 2). There was marked difference in the gender distribution between Group 2 and isolated TBMN patients. The degree of proteinuria and pathologic severity was higher in Group 1 compared with Group 2. Gross hematuria was present in both groups. There were no distinguishing features in the other laboratory parameters. CONCLUSION: Patients with both IgAN and TBMN seem to have similar clinical features to patients with isolated IgAN; however, the latter tend to have better pathologic and laboratory findings, compared to the patients with IgAN alone.

Podocytopathy and Morphologic Changes in Focal Segmental Glomerulosclerosis

Podocytopathy is glomerular lesions characterized by podocyte injury. It is observed in various glomerular diseases, but minimal change disease and focal segmental glomerulosclerosis (FSGS) are the prototypes. In this review, morphologic features of podocyte injury and subtypes of FSGS will be reviewed briefly. Effacement of podocyte foot processes is the most common feature of podocyte injury. As podocytic injury progresses, intracytoplasmic vacuoles, subpodocytic cyst, detachment of podocytes from the glomerular basement membrane and apoptosis develop. Glomerular capillary loops in epithelium-denuded area undergo capillary collapse. Synechia and hyalinosis may accompany this lesion. To manifest segmental sclerosis, podocyte loss above a threshold level may be required. Injured podocytes can injure neighboring intact podocytes, and thereby spread injury within the same lobule. FSGS can be categorized into five subtypes by morphologic characteristics; not otherwise specified (NOS), perihilar, cellular, tip, and collapsing types. Each subtype has been reported to show different clinical courses and associated conditions, but there are controversies on its significance. With recent progress in the discovery of genetic abnormalities causing FSGS and plasma permeability factors, we expect to unravel pathophysiology of FSGS and to understand histological sequences leading to FSGS in near future.

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.

Impact of gene polymorphisms of interleukin-18, transforming growth factor-beta, and vascular endothelial growth factor on development of IgA nephropathy and thin glomerular basement membrane disease

BACKGROUND: We investigated the effects of gene polymorphisms on the development of IgA nephropathy and thin glomerular basement membrane (GBM) disease by analyzing polymorphisms in the interleukin (IL)-18, transforming growth factor (TGF)-beta, and vascular endothelial growth factor (VEGF) genes in Korean patients. METHODS: This study included 146 normal individuals and 69 biopsy-proven IgA nephropathy and 44 thin GBM disease patients. The gene polymorphisms -607A/C and -137G/C in IL-18, -509C/T and T869C in TGF-beta, and -2578C/A and 405C/G in VEGF were investigated in DNA extracted from peripheral blood. RESULTS: The frequencies of the IL-18 -607CC genotype (43.5% vs. 21.2%, P=0.002, P corrected=0.012) and the VEGF 405GG genotype (37.7% vs. 21.2%, P=0.002, P corrected=0.012) were significantly increased in the IgA nephropathy group compared with the control group, whereas no significant differences in genotype frequency were observed between the thin GBM disease and control groups. However, there were no significant differences in genotype and allele frequencies between the IgA nephropathy and thin GBM disease groups. CONCLUSION: This study did not show any statistically significant differences of six selected gene polymorphisms of the IL-18, TGF-beta, and VEGF genes between IgA nephropathy and thin GBM disease. Additional extensive studies are required to clarify the potential role of gene polymorphism to discriminate IgA nephropathy and thin GBM disease without renal biopsy.