A Model of Strain-Dependent Glomerular Basement Membrane Maintenance and Its Potential Ramifications in Health and Disease

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Victor H. Barocas ◽  
Kevin D. Dorfman ◽  
Yoav Segal
Keyword(s):  
Pressure Drop ◽  
Basement Membrane ◽  
Glomerular Basement Membrane ◽  
Alport Syndrome ◽  
Published Data ◽  
Model Parameters ◽  
Structural Element ◽  
Tissue Strain ◽  
Thin Basement Membrane Disease ◽  
Gbm Thickening

A model is developed and analyzed for type IV collagen turnover in the kidney glomerular basement membrane (GBM), which is the primary structural element in the glomerular capillary wall. The model incorporates strain dependence in both deposition and removal of the GBM, leading to an equilibrium tissue strain at which deposition and removal are balanced. The GBM thickening decreases tissue strain per unit of transcapillary pressure drop according to the law of Laplace, but increases the transcapillary pressure drop required to maintain glomerular filtration. The model results are in agreement with the observed GBM alterations in Alport syndrome and thin basement membrane disease, and the model-predicted linear relation between the inverse capillary radius and inverse capillary thickness at equilibrium is consistent with published data on different mammals. In addition, the model predicts a minimum achievable strain in the GBM based on the geometry, properties, and mechanical environment; that is, an infinitely thick GBM would still experience a finite strain. Although the model assumptions would be invalid for an extremely thick GBM, the minimum achievable strain could be significant in diseases, such as Alport syndrome, characterized by focal GBM thickening. Finally, an examination of reasonable values for the model parameters suggests that the oncotic pressure drop—the osmotic pressure difference between the plasma and the filtrate due to large molecules—plays an important role in setting the GBM strain and, thus, leakage of protein into the urine may be protective against some GBM damage.

scholarly journals Thin basement membrane disease – literature review

2015 ◽  
Vol 84 (3) ◽  
pp. 201-204
Author(s):  
Jakub Żurawski
Keyword(s):  
Electron Microscope ◽  
Basement Membrane ◽  
Literature Review ◽  
Iga Nephropathy ◽  
Glomerular Basement Membrane ◽  
Alport Syndrome ◽  
Clinical Course ◽  
Renal Diseases ◽  
Renal Lithiasis ◽  
Thin Basement Membrane Disease

Initially, the thin glomerular basement membrane disease was called “a gentle and curable hemorrhagic nephritis”. The thin basement membrane disease has been finally characterized at the beginning of 1970s. This is when the connection between previously clinically described gentle microhematuria and significant thinning of glomerular basement membrane discovered during examination under the electron-microscope has been established. Ultimately, the disease has been described as a condition characterized with a diverse clinical course, usually mild, but sometimes progressive. It is a family conditioned disease, but it also appears sporadically and concerns at least 1% of the population. It has also been stated that it is one of the most frequent renal diseases, enumerated directly after changes caused by infections, hypertension and renal lithiasis. This particular disease is diagnosed more often than IgA nephropathy and Alport syndrome, which are also associated with haematuria or microhematuria.

scholarly journals Prevalence of clinical, pathological and molecular features of glomerular basement membrane nephropathy caused by COL4A3 or COL4A4 mutations: a systematic review

2020 ◽  
Vol 13 (6) ◽  
pp. 1025-1036 ◽  
Author(s):  
Andreas Matthaiou ◽  
Tsielestina Poulli ◽  
Constantinos Deltas
Keyword(s):  
Basement Membrane ◽  
Alport Syndrome ◽  
Autosomal Dominant ◽  
Wide Spectrum ◽  
Age At Onset ◽  
Histological Finding ◽  
Basement Membranes ◽  
Thin Basement Membrane Nephropathy ◽  
Molecular Features ◽  
Thin Basement Membrane Disease

Abstract Background Patients heterozygous for COL4A3 or COL4A4 mutations show a wide spectrum of disease, extending from familial isolated microscopic haematuria, as a result of thin basement membranes (TBMs), to autosomal dominant Alport syndrome (ADAS) and end-stage renal disease (ESRD). Many patients are mentioned in the literature under the descriptive diagnosis of TBM nephropathy (TBMN), in which case it actually describes a histological finding that represents the carriers of autosomal recessive Alport syndrome (ARAS), a severe glomerulopathy, as most patients reach ESRD at a mean age of 25 years. Methods We performed a systematic literature review for patients with heterozygous COL4A3/A4 mutations with the aim of recording the spectrum and frequency of pathological features. We searched three databases (PubMed, Embase and Scopus) using the keywords ‘Autosomal Dominant Alport Syndrome’ OR ‘Thin Basement Membrane Disease’ OR ‘Thin Basement Membrane Nephropathy’. We identified 48 publications reporting on 777 patients from 258 families. Results In total, 29% of the patients developed chronic kidney disease (CKD) and 15.1% reached ESRD at a mean age of 52.8 years. Extrarenal features and typical Alport syndrome (AS) findings had a low prevalence in patients as follows: hearing loss, 16%; ocular lesions, 3%; basement membrane thickening, 18.4%; and podocyte foot process effacement, 6.9%. Data for 76 patients from 54 families emphasize extensive inter- and intrafamilial heterogeneity, with age at onset of ESRD ranging between 21 and 84 years (mean 52.8). Conclusions The analysis enabled a comparison of the clinical course of patients with typical ARAS or X-linked AS with those with heterozygous COL4A mutations diagnosed with TBMN or ADAS. Despite the consequence of a potential ascertainment bias, an important outcome is that TBM poses a global high risk of developing severe CKD, over a long follow-up, with a variable spectrum of other findings. The results are useful to practicing nephrologists for better evaluation of patients.

scholarly journals Tensin2 is important for podocyte-glomerular basement membrane interaction and integrity of the glomerular filtration barrier

2020 ◽  
Vol 318 (6) ◽  
pp. F1520-F1530
Author(s):  
Kozue Uchio-Yamada ◽  
Keiko Yasuda ◽  
Yoko Monobe ◽  
Ken-ichi Akagi ◽  
Osamu Suzuki ◽  
...  
Keyword(s):  
Basement Membrane ◽  
Glomerular Filtration ◽  
Glomerular Basement Membrane ◽  
Dependent Manner ◽  
Glomerular Filtration Barrier ◽  
Filtration Barrier ◽  
Gbm Thickening ◽  
Strain Dependent ◽  
Deficient Mice

Tensin2 (Tns2), an integrin-linked protein, is enriched in podocytes within the glomerulus. Previous studies have revealed that Tns2-deficient mice exhibit defects of the glomerular basement membrane (GBM) soon after birth in a strain-dependent manner. However, the mechanisms for the onset of defects caused by Tns2 deficiency remains unidentified. Here, we aimed to determine the role of Tns2 using newborn Tns2-deficient mice and murine primary podocytes. Ultrastructural analysis revealed that developing glomeruli during postnatal nephrogenesis exhibited abnormal GBM processing due to ectopic laminin-α2 accumulation followed by GBM thickening. In addition, analysis of primary podocytes revealed that Tns2 deficiency led to impaired podocyte-GBM interaction and massive expression of laminin-α2 in podocytes. Our study suggests that weakened podocyte-GBM interaction due to Tns2 deficiency causes increased mechanical stress on podocytes by continuous daily filtration after birth, resulting in stressed podocytes ectopically producing laminin-α2, which interrupts GBM processing. We conclude that Tns2 plays important roles in the podocyte-GBM interaction and maintenance of the glomerular filtration barrier.

scholarly journals Albumin contributes to kidney disease progression in Alport syndrome

2016 ◽  
Vol 311 (1) ◽  
pp. F120-F130 ◽  
Author(s):  
George Jarad ◽  
Russell H. Knutsen ◽  
Robert P. Mecham ◽  
Jeffrey H. Miner
Keyword(s):  
Kidney Disease ◽  
Basement Membrane ◽  
Glomerular Basement Membrane ◽  
Alport Syndrome ◽  
Transforming Growth Factor ◽  
Kidney Diseases ◽  
Serum Triglyceride ◽  
Transforming Growth Factor Β ◽  
Collagen Type Iv ◽  
Albumin Concentration

Alport syndrome is a familial kidney disease caused by defects in the collagen type IV network of the glomerular basement membrane. Lack of collagen-α3α4α5(IV) changes the glomerular basement membrane morphologically and functionally, rendering it leaky to albumin and other plasma proteins. Filtered albumin has been suggested to be a cause of the glomerular and tubular injuries observed at advanced stages of Alport syndrome. To directly investigate the role that albumin plays in the progression of disease in Alport syndrome, we generated albumin knockout ( Alb−/−) mice to use as a tool for removing albuminuria as a component of kidney disease. Mice lacking albumin were healthy and indistinguishable from control littermates, although they developed hypertriglyceridemia. Dyslipidemia was observed in Alb+/− mice, which displayed half the normal plasma albumin concentration. Alb mutant mice were bred to collagen-α3(IV) knockout ( Col4a3−/−) mice, which are a model for human Alport syndrome. Lack of circulating and filtered albumin in Col4a3−/−; Alb−/− mice resulted in dramatically improved kidney disease outcomes, as these mice lived 64% longer than did Col4a3−/−; Alb+/+ and Col4a3−/−; Alb+/− mice, despite similar blood pressures and serum triglyceride levels. Further investigations showed that the absence of albumin correlated with reduced transforming growth factor-β1 signaling as well as reduced tubulointerstitial, glomerular, and podocyte pathology. We conclude that filtered albumin is injurious to kidney cells in Alport syndrome and perhaps in other proteinuric kidney diseases, including diabetic nephropathy.

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