scholarly journals Truncated Variant of ASIC2b Confers Epithelial Sodium Channel Properties to ASIC2: Role in Nephrotic Syndrome

2015 ◽  
Vol 29 (S1) ◽  
Author(s):  
Alain Doucet ◽  
Ali Sassi ◽  
Gaelle Brideau ◽  
Lydie Cheval ◽  
Bruno Vogt ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Sodium Channel ◽  
Epithelial Sodium Channel ◽  
Channel Properties

Experimental nephrotic syndrome leads to proteolytic activation of the epithelial sodium channel (ENaC) in the mouse kidney

2021 ◽  
Author(s):  
Bernhard N. Bohnert ◽  
Daniel Essigke ◽  
Andrea Janessa ◽  
Jonas C Schneider ◽  
Matthias Wörn ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Sodium Channel ◽  
Serine Protease ◽  
Cleavage Site ◽  
Mineralocorticoid Receptor ◽  
Epithelial Sodium Channel ◽  
Sodium Retention ◽  
Cleavage Sites ◽  
Proteolytic Activation ◽  
Epithelial Sodium Channel Enac

Proteolytic activation of the renal epithelial sodium channel ENaC involves cleavage events in its α- and γ-subunits and is thought to mediate sodium retention in nephrotic syndrome (NS). However, detection of proteolytically processed ENaC in kidney tissue from nephrotic mice has been elusive so far. We used a refined Western blot technique to reliably discriminate full-length α- and γ-ENaC and their cleavage products after proteolysis at their proximal and distal cleavage sites (designated from the N-terminus), respectively. Proteolytic ENaC activation was investigated in kidneys from mice with experimental NS induced by doxorubicin or inducible podocin deficiency with or without treatment with the serine protease inhibitor aprotinin. Nephrotic mice developed sodium retention and increased expression of fragments of α- and γ-ENaC cleaved at both the proximal and more prominently at the distal cleavage site, respectively. Treatment with aprotinin but not with the mineralocorticoid receptor antagonist canrenoate prevented sodium retention and upregulation of the cleavage products in nephrotic mice. Increased expression of cleavage products of α- and γ-ENaC was similarly found in healthy mice treated with a low salt diet, sensitive to mineralocorticoid receptor blockade. In human nephrectomy specimens, γ-ENaC was found in the full-length form and predominantly cleaved at its distal cleavage site. In conclusion, murine experimental NS leads to aprotinin-sensitive proteolytic activation of ENaC at both proximal and more prominently distal cleavage sites of its α- and γ-subunit, most likely by urinary serine protease activity or proteasuria.

Pathogenesis of oedema in nephrotic syndrome: Role of epithelial sodium channel

Nephrology ◽  
2007 ◽  
Vol 12 (s3) ◽  
pp. S8-S10 ◽  
Author(s):  
SOO WAN KIM ◽  
JØRGEN FRØKIÆR ◽  
SØREN NIELSEN
Keyword(s):  
Nephrotic Syndrome ◽  
Sodium Channel ◽  
Epithelial Sodium Channel

Association of Urinary Plasminogen-Plasmin with Edema and Epithelial Sodium Channel Activation in Patients with Nephrotic Syndrome

2019 ◽  
Vol 50 (2) ◽  
pp. 92-104 ◽  
Author(s):  
Jun-Liang Chen ◽  
Li Wang ◽  
Xing-Mei Yao ◽  
Ying-Jun Zang ◽  
Yi Wang ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Sodium Channel ◽  
Influencing Factor ◽  
Fractional Excretion ◽  
Epithelial Sodium Channel ◽  
Pathophysiological Mechanism ◽  
Sodium Retention ◽  
Edema Formation ◽  
Fractional Excretion Of Sodium ◽  
Serial Samples

Background: Previous animal experiments and small human studies suggest that urinary plasmin can activate the epithelial sodium channel (ENaC) and contribute to sodium retention in nephrotic syndrome (NS), but this however is not well studied in clinical settings, and its relevance to edema formation is not well characterized in humans. We have investigated the association between urinary plasmin and clinical phenotypes in a large group of patients with NS from multiple etiologies, aiming to assess the role of urinary plasmin in sodium handling and edema formation. Methods: Two hundred and three NS patients with urine and blood samples were divided into mild and severe symptom groups based on their edema severity. Twenty six of them had serial samples collected during the course of immunosuppressive therapy. The plasminogen-plasmin level and other key parameters were assayed, and their association with clinical manifestations were analyzed. Results: One hundred and one of the 203 patients had renal biopsies performed, the results of which had included all the common types of primary NS and various types of secondary NS. Quantitative comparison and multivariate logistic regression analysis identified urinary plasminogen-plasmin to creatinine ratio (uPLG-PL/C), serum albumin, D-Dimer, and cardiac dysfunction history, but not albuminuria or 24-h urine protein, as independent risk factors for edema (p < 0.01). In patients who were treated and had serial samples, a decrease in uPLG-PL/C was identified as an independent influencing factor of edema remission (p < 0.01). Finally, the urinary fractional excretion of sodium (FENa) in patients was inversely correlated with the fractional excretion of potassium (FEK; p< 0.001), and FEK/FENa ratio was positively correlated with uPLG-PL/C (p < 0.001), suggesting a close association between uPLG-PL and ENaC activation. Conclusions: Our study identifies uPLG-PL abundance as an independent influencing factor of edema in adult NS patients, and supports the conclusion that plasmin-dependent ENaC activation is an important pathophysiological mechanism of sodium retention and edema formation in humans with NS.

scholarly journals Aprotinin prevents proteolytic epithelial sodium channel (ENaC) activation and volume retention in nephrotic syndrome

2018 ◽  
Vol 93 (1) ◽  
pp. 159-172 ◽  
Author(s):  
Bernhard N. Bohnert ◽  
Martina Menacher ◽  
Andrea Janessa ◽  
Matthias Wörn ◽  
Anja Schork ◽  
...  
Keyword(s):  
Nephrotic Syndrome ◽  
Sodium Channel ◽  
Epithelial Sodium Channel ◽  
Volume Retention ◽  
Epithelial Sodium Channel Enac

scholarly journals Perspectives on edema in childhood nephrotic syndrome

2015 ◽  
Vol 309 (7) ◽  
pp. F575-F582 ◽  
Author(s):  
Chia Wei Teoh ◽  
Lisa A. Robinson ◽  
Damien Noone
Keyword(s):  
Nephrotic Syndrome ◽  
Sodium Channel ◽  
Epithelial Sodium Channel ◽  
Childhood Nephrotic Syndrome ◽  
Glomerular Filtrate ◽  
Epithelial Sodium Channel Enac

There have been two major theories surrounding the development of edema in nephrotic syndrome (NS), namely, the under- and overfill hypotheses. Edema is one of the cardinal features of NS and remains one of the principal reasons for admission of children to the hospital. Recently, the discovery that proteases in the glomerular filtrate of patients with NS are activating the epithelial sodium channel (ENaC), resulting in intrarenal salt retention and thereby contributing to edema, might suggest that targeting ENaC with amiloride might be a suitable strategy to manage the edema of NS. Other potential agents, particularly urearetics and aquaretics, might also prove useful in NS. Recent evidence also suggests that there may be other areas involved in salt storage, especially the skin, and it will be intriguing to study the implications of this in NS.

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