scholarly journals Preclinical evaluation of the epithelial sodium channel inhibitor BI 1265162 for treatment of cystic fibrosis

2020 ◽  
Vol 6 (4) ◽  
pp. 00429-2020 ◽  
Author(s):  
Peter Nickolaus ◽  
Birgit Jung ◽  
Juan Sabater ◽  
Samuel Constant ◽  
Abhya Gupta
Keyword(s):  
Cystic Fibrosis ◽  
Sodium Channel ◽  
Water Transport ◽  
Collecting Duct ◽  
Epithelial Sodium Channel ◽  
Liquid Volume ◽  
Liquid Absorption ◽  
Cftr Modulators

BackgroundEpithelial sodium channel (ENaC) is an important regulator of airway surface liquid volume; ENaC is hyperactivated in cystic fibrosis (CF). ENaC inhibition is a potential therapeutic target for CF. Here, we report in vitro and in vivo results for BI 1265162, an inhaled ENaC inhibitor currently in Phase II clinical development, administered via the Respimat® Soft Mist™ inhaler.MethodsIn vitro inhibition of sodium ion (Na+) transport by BI 1265162 was tested in mouse renal collecting duct cells (M1) and human bronchial epithelial cells (NCI-H441); inhibition of water transport was measured using M1 cells. In vivo inhibition of liquid absorption from rat airway epithelium and acceleration of mucociliary clearance (MCC) in sheep lungs were assessed. Fully differentiated normal and CF human epithelium was used to measure the effect of BI 1265162 with or without ivacaftor and lumacaftor on water transport and MCC.ResultsBI 1265162 dose-dependently inhibited Na+ transport and decreased water resorption in cell line models. BI 1265162 reduced liquid absorption in rat lungs and increased MCC in sheep. No effects on renal function were seen in the animal models. BI 1265162 alone and in combination with CF transmembrane conductance regulator (CFTR) modulators decreased water transport and increased MCC in both normal and CF airway human epithelial models and also increased the effects of CFTR modulators in CF epithelium to reach the effect size seen in healthy epithelium with ivacaftor/lumacaftor alone.ConclusionThese results demonstrate the potential of BI 1265162 as a mutation agnostic, ENaC-inhibitor-based therapy for CF.

scholarly journals Azithromycin Inhibits Constitutive Airway Epithelial Sodium Channel Activation in Vitro and Modulates Downstream Pathogenesis in Vivo

2020 ◽  
Vol 43 (4) ◽  
pp. 725-730 ◽  
Author(s):  
Haruka Fujikawa ◽  
Taise Kawakami ◽  
Ryunosuke Nakashima ◽  
Aoi Nasu ◽  
Shunsuke Kamei ◽  
...  
Keyword(s):  
Sodium Channel ◽  
Epithelial Sodium Channel ◽  
Airway Epithelial ◽  
Channel Activation ◽  
Sodium Channel Activation

scholarly journals Conditional Transgenic Mice for Studying the Role of the Glucocorticoid Receptor in the Renal Collecting Duct

Endocrinology ◽  
2008 ◽  
Vol 150 (5) ◽  
pp. 2202-2210 ◽  
Author(s):  
Aurélie Nguyen Dinh Cat ◽  
Antoine Ouvrard-Pascaud ◽  
François Tronche ◽  
Maud Clemessy ◽  
Daniel Gonzalez-Nunez ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Glucocorticoid Receptor ◽  
Sodium Channel ◽  
Leucine Zipper ◽  
Collecting Duct ◽  
Extracellular Volume ◽  
Epithelial Sodium Channel ◽  
Sodium Reabsorption ◽  
Renal Collecting Duct

The mineralocorticoid receptor (MR) is a major regulator of renal sodium reabsorption and body fluid homeostasis. However, little is known about glucocorticoid receptor (GR)-dependent renal effects. Glucocorticoids may activate both receptors, so it is difficult to distinguish between MR- and GR-mediated effects in vivo. To overcome this complexity, we used a transgenic mouse model allowing conditional GR overexpression (doxycycline inducible TetON system, Hoxb7 promoter) in the renal collecting duct (CD) to identify GR-regulated genes involved in sodium transport in the CD. In microdissected cortical CD, induction of GR expression led (after 2 d of doxycycline) to increased α-epithelial sodium channel and glucocorticoid-induced leucine zipper and decreased abundance of with-no-lysine kinase 4 transcripts, without modification of Na,K-ATPase, serum- and glucocorticoid-kinase-1, or MR expression. No changes occurred in the upstream distal and connecting tubules [distal convoluted tubule (DCT), connecting tubule (CNT)]. Sodium excretion was unaltered, but the urinary aldosterone concentration was reduced, suggesting compensation of transitory extracellular volume expansion that subsequently disappeared. At steady state, i.e. after 15 d of doxycycline administration, transcript abundance remained altered in the CD, whereas mirror changes appeared in the DCT and CNT. Plasma aldosterone or glucocorticoids and blood pressure were all unaffected. These experiments show that: 1) GR, in addition to MR, controls epithelial sodium channel- and glucocorticoid-induced leucine zipper expression in vivo in the CD; 2) with-no-lysine kinase 4 is negatively controlled by GR; and 3) the DCT and CNT compensate for these alterations to maintain normal sodium reabsorption and blood pressure. These results suggest that enhanced GR expression may contribute to enhanced sodium retention in some pathological situations.

scholarly journals Iron Inhibits the Translation and Activity of the Renal Epithelial Sodium Channel

Biology ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 123
Author(s):  
Abdel A. Alli ◽  
Ling Yu ◽  
Ewa Wlazlo ◽  
Sadat Kasem ◽  
Mohammed F. Gholam ◽  
...  
Keyword(s):  
Sodium Channel ◽  
Knockout Mice ◽  
Collecting Duct ◽  
Iron Chelation ◽  
Epithelial Sodium Channel ◽  
Renal Tubules ◽  
Local Responses ◽  
Collecting Duct Cells ◽  
Expression And Activity

Hypertension is associated with an increased renal expression and activity of the epithelial sodium channel (ENaC) and iron deficiency. Distal tubules absorb iron, causing perturbations that may influence local responses. In this observational study, we investigated the relationship between iron content and ENaC expression and activity using two cell lines and hepcidin knockout mice (a murine model of iron overload). We found that iron did not transcriptionally regulate ENaC in hepcidin knockout mice or in vitro in collecting duct cells. However, the renal tubules of hepcidin knockout mice have a lower expression of ENaC protein. ENaC activity in cultured Xenopus 2F3 cells and mpkCCD cells was inhibited by iron, which could be reversed by iron chelation. Thus, our novel findings implicate iron as a regulator of ENaC protein and its activity.

Trypsin can activate the epithelial sodium channel (ENaC) in microdissected mouse distal nephron

2008 ◽  
Vol 295 (4) ◽  
pp. F1052-F1062 ◽  
Author(s):  
Viatcheslav Nesterov ◽  
Anke Dahlmann ◽  
Marko Bertog ◽  
Christoph Korbmacher
Keyword(s):  
Sodium Channel ◽  
Collecting Duct ◽  
Epithelial Sodium Channel ◽  
Extracellular Proteases ◽  
Whole Cell ◽  
Renal Tubular Cells ◽  
Endogenous Proteases ◽  
Renal Tubular ◽  
Epithelial Sodium Channel Enac

Proteases are involved in the processing and activation of the epithelial sodium channel (ENaC). The aim of the present study was to investigate whether the prototypical serine protease trypsin can activate ENaC in microdissected, split-open mouse renal distal tubules. Whole-cell patch-clamp recordings from principal cells of connecting tubules (CNT) or cortical collecting ducts (CCD) demonstrated that addition of trypsin (20 μg/ml) to the bath solution increased the ENaC-mediated amiloride-sensitive whole cell current (Δ IAmi) in the majority of cells. In contrast, trypsin applied in the presence of an excess of soybean trypsin inhibitor had no stimulatory effect. The Δ IAmi response to trypsin was variable, ranging from no apparent effect to a twofold increase in Δ IAmi with an average stimulatory effect of 31 or 37% in mice on low-Na+ or standard Na+ diet, respectively. In cultured M-1 mouse collecting duct cells, a robust stimulatory effect of trypsin on Δ IAmi was only observed in cells pretreated with protease inhibitors. This suggests that endogenous proteases contribute to ENaC activation in renal tubular cells and that the degree of ENaC prestimulation by endogenous proteases determines the magnitude of the stimulatory response to exogenous trypsin. In conclusion, we provide electrophysiological evidence that trypsin can stimulate ENaC activity in native renal mouse tubules. Thus, in the kidney, ENaC stimulation by extracellular proteases may be a relevant regulatory mechanism in vivo.

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