Biology subjects

Feraille, E.

Publications and source records attributed to Feraille, E..

7 recordsLinked to original sources

bioRxiv2026

Low-salt diet induces claudin-3 expression and drives adaptive changes in collecting duct of claudin-3-deficient mice

BackgroundRenal sodium reabsorption occurs via both transcellular and paracellular pathways. Tight junction proteins play a key role in mediating paracellular transport. The collecting duct (CD) is critical for the fine-tuning of Na+ balance and is sensitive to changes in dietary salt intake. A low-sodium diet, which increases endogenous aldosterone secretion, stimulates transcellular sodium transport via epithelial Na+ channels (ENaC) and Na,K-ATPase. We hypothesized that a low-sodium diet also modulates paracellular Na+ permeability by regulating the expression or function of claudin-3, a major tight junction protein in the CD, in order to limit the back-leak of reabsorbed sodium and preserve sodium balance. MethodsWe used in vivo mouse models and cultured mouse CD principal cells (mCCDcl1) to assess aldosterones effects on tight junction proteins. In mCCDcl1 cells, aldosterone-induced changes in claudin-3 expression and localization were evaluated via Western blotting and immunofluorescence, and Ussing chamber assays were used to assess paracellular Na+ and Cl- permeability after modulating claudin-3 expression. Wild-type and claudin-3 knockout mice were fed low (0.01%) or normal (0.18%) sodium diets for seven days. In subsets of low sodium diet mice, spironolactone (a mineralocorticoid receptor antagonist) was administered. ResultsIn mice, a low-sodium diet upregulates renal claudin-3 expression. Concordantly, in vitro studies using mCCDcl1 cells showed that aldosterone treatment increased claudin-3 protein levels and promoted its localization to the lateral membrane. Functional analyses demonstrated that claudin-3 overexpression reduced paracellular permeability to both Na+ and Cl-, while claudin-3 silencing increased it. Claudin-3 knockout mice subjected to a low-sodium diet exhibited compensatory upregulation of the - and {gamma}-subunits of ENaC, alongside increased expression of claudin-4, claudin-8, and claudin-10. This highlights an adaptive response that maintains sodium homeostasis in the absence of claudin-3. Importantly, this compensatory mechanism persists even under spironolactone treatment, suggesting that the adaptation of claudin-3-deficient mice occurs independently of mineralocorticoid receptor activation. ConclusionsOur findings demonstrate that aldosterone enhances claudin-3 expression, reinforcing the paracellular barrier to Na+ and complementing its classical role in transcellular Na+ transport. Under low-sodium conditions, claudin-3-deficient mice adapt through complementary mechanisms aimed at increasing sodium reabsorption via ENaC activation and upregulation of claudin-4 and claudin-8, both barrier-forming claudins that restrict paracellular sodium leakage in the CD. This is associated with increased claudin-10 abundance in the thick ascending limb of Henle, a pore-forming claudin that facilitates paracellular sodium permeability. This study advances our understanding of the complex control of renal sodium handling, revealing adaptive mechanisms in response to low-salt diet and claudin-3 deficiency.

physiology↗

bioRxiv2025

High-salt diet modulates endocrine regulation between cortisol and FGF23

Excessive dietary salt intake is a global health concern, affecting cardiovascular, renal, and bone health. While the renin-angiotensin-aldosterone system (RAAS) is a known regulator of dietary salt-induced hormonal responses, the impact of adrenal cortisol remains unclear. Here, we performed a retrospective analysis in individuals (n=292) consuming a random diet. Dietary salt intake positively correlated with urinary cortisol and inversely correlated with plasma fibroblast growth factor 23 (FGF23), a bone-derived hormone regulating phosphate and vitamin D homeostasis. Controlled salt diets in healthy individuals confirmed a dose-dependent increase in urinary cortisol and suppression of plasma FGF23. In mice, oral corticosterone, a cortisol analogue, reduced circulating FGF23 levels. RNA-seq analysis of corticosterone-treated MC3T3 osteoblasts identified suppression of FGF23 via glucocorticoid receptor activation, anti-inflammatory pathways, and reduced osteoblast activity. Our findings reveal a novel endocrine cascade where high salt intake elevates cortisol and suppresses FGF23, with potential implications for bone, kidney, and cardiovascular health. SIGNIFICANCE STATEMENTExcessive dietary salt intake is a global health concern with poorly understood hormonal consequences beyond the renin-angiotensin-aldosterone system. Here, we identify a novel endocrine cascade in which high salt intake elevates cortisol signaling and suppresses fibroblast growth factor 23 (FGF23), a bone-derived hormone central to phosphate and vitamin D homeostasis. These findings are supported by a human cohort on random diets, a controlled dietary salt intervention, and corticosterone experiments in mice and osteoblasts. Mechanistically, cortisol suppresses FGF23 via glucocorticoid receptor activation, anti-inflammatory signaling, and repression of osteoblast activity. These findings have potential implications for bone, kidney, and cardiovascular health, and suggest that dietary salt intake may influence the clinical interpretation of cortisol and FGF23 measurements.

physiology↗

bioRxiv2025

Tissular glucocorticoid reactivating enzyme 11beta-HSD1 drives pathogenic myofibroblast differentiation in chronic kidney disease

Chronic kidney disease (CKD) is a growing public health crisis, affecting over 10% of the global population and significantly increasing mortality and morbidity. Irrespective of its underlying cause, tubulointerstitial fibrosis (TIF) is a hallmark of CKD progression, with myofibroblasts being the primary effectors of renal fibrosis. Here, we show that 11beta-hydroxysteroid dehydrogenase type 1 (11{beta}-HSD1) is a critical driver of pathogenic myofibroblast differentiation and fibrosis in CKD. Using genetic deletion and pharmacological inhibition of 11{beta}-HSD1 in mouse models, we demonstrate a marked reduction in TIF severity and improved renal function, linked to the suppression of a regulatory myofibroblast (Reg-MF) subpopulation. Single-cell and spatial transcriptomics data reveal that 11{beta}-HSD1 is essential for the activation and expansion of Reg-MFs, which is conserved across species and predicts worse outcomes in CKD patients and kidney allograft recipients. These findings establish a direct link between 11{beta}-HSD1 activity and renal fibrogenesis, highlighting its role during the transition from pericytes to pathogenic Reg-MFs. Our results support 11{beta}-HSD1 inhibition as a promising therapeutic strategy to mitigate CKD progression, offering both mechanistic insights and translational potential for improving patient outcomes.

physiology↗

bioRxiv2024

The preferential injury of outer renal medulla after ischemia-reperfusion relies on high oxidative metabolism

Acute kidney injury (AKI) is a prevalent and significant complication in critically ill patients, and its management remains a considerable challenge. The kidney is a highly metabolic organ, consuming and producing substantial amounts of ATP, mainly through mitochondrial oxidative phosphorylation. Recently, mitochondrial dysfunction has been identified as a key factor in the pathophysiology of AKI and the progression to chronic kidney disease. The kidney is a complex organ, comprising millions of structural and functional units. These nephrons are composed of different cell types dwelling within specific metabolic microenvironment. Whether the metabolic spatialization in the kidney has consequences on tubular injury distribution and severity remains unclear. In this study, we identified the high metabolic rate of the outer stripe of the outer medulla (OSOM) and its substrate preference flexibility, relying on both glycolysis and fatty acid oxidation (FAO) to fulfill its ATP demands. We demonstrated that the OSOM is susceptible to mitochondrial and FAO impairment induced by propofol, the most used sedative in intensive care settings, which exacerbates tubular injury during AKI. In the clinical setting, the cumulative dose of propofol is positively correlated with oxidative metabolism disruption and histological and function outcomes in renal allograft recipients. Finally, we found that the loop of Henle, the OSOM major constituent, was the most injured segment during AKI in patients. This study shows how renal metabolic spatialization impacts tubular injury severity. We identified the OSOM as the most metabolically active and the most injured region of the kidney both in humans and mice. We demonstrated that propofol is a potent inhibitor of renal mitochondrial function and FAO exacerbating tubular injury in the OSOM upon IRI. Translational StatementO_LIAerobic metabolism is basally enhanced in the renal OSOM, including the S3 proximal tubule, the thick ascending limb of the loop of Henle and Distal Convoluted Tubule C_LIO_LIPT cells as well as TAL cells are significantly targeted by injury in human AKI. C_LIO_LIPropofol impairs renal mitochondrial function worsening tubular injury during ischemia reperfusion. C_LI

physiology↗

bioRxiv2022

Increased severity of chronic kidney disease in response to high potassium intake is dependent on mineralocorticoid receptor activation

Dietary treatment is seminal for management of chronic kidney disease (CKD). The aim of our project was to assess the effects of potassium intake on the progression of CKD. We used 2 mouse CKD models to analyze the effects of potassium intake on CKD : the unilateral ureteral obstruction (UUO) and the POD-ATTAC models. POD-ATTAC mice display a podocyte-specific apoptosis after the administration of a chemical inducer. We also studied the effect of mineralocorticoid receptor (MR) using UUO in kidney tubule-specific MR knockout mice. In both UUO and POD-ATTAC mice, high potassium diet increased interstitial fibrosis. High potassium diet also increased the abundance of the extracellular matrix protein fibronectin and decreased the abundance of the epithelial marker Na+-K+ ATPase. Consistently, POD-ATTAC mice fed with high potassium diet displayed lower glomerular filtration rate. Spironolactone, a MR antagonist, decreased fibrosis induced by high potassium diet in POD-ATTAC mice. However, kidney tubule-specific MR knockout did not improve the fibrotic lesions induced by UUO under normal or high potassium diets. Macrophages from high potassium-fed POD-ATTAC mice displayed higher mRNA levels of the pro-inflammatory chemokine MCP1. This effect was decreased by spironolactone, suggesting a role of MR signaling in myeloid cells in the pro-fibrotic effect of potassium-rich diet. High potassium intake generates more fibrosis leading to decreased kidney function in experimental CKD. MR signaling plays a pivotal role in this potassium-induced fibrosis. The effect of reducing potassium intake on CKD progression should be assessed in future clinical trials. Translational statementDietetic approach is a cheap and effective therapy to slow down the development of chronic kidney diseases and kidney fibrosis. Potassium-rich diets are protective against renal and cardiovascular events in the general population, albeit some conflicting data were obtained in patients with chronic kidney disease. We showed that potassium-rich diet accelerates fibrosis development, by enhancing kidney inflammation in two mouse models of chronic kidney disease. These data suggest that potassium-rich diets should not be advised in patients with chronic kidney disease, unless future clinical trials demonstrate any beneficial effect in these patients.

physiology↗

bioRxiv2022

Claudin-4, a core component of the tight-junctional complex along the collecting system, is induced in nephrotic syndrome

BackgroundNephrotic syndrome (NS) is characterized by massive sodium chloride retention. Along the kidney tubule, sodium and chloride reabsorption are coupled via a combination of transcellular and paracellular transport pathways. The mechanism of sodium retention in NS has been extensively studied, but the associated chloride transport pathway has not been elucidated. MethodsTo investigate the pathway of chloride retention in NS, we assessed the expression levels of both paracellular and transcellular components of chloride transport in the CD of POD-ATTAC mice and PAN rats, two rodent models of NS. We also used cultured mouse cortical collecting duct cells to see how overexpression or silencing of claudin-4 affect paracellular permeability. Finally, human renal biopsies were used to confirm our in vivo results. ResultsIn control animals, claudin-4 was expressed at low levels in collecting duct (CD). In POD-ATTAC mice and PAN rats, claudin-4 expression was strongly increased in CD beta-intercalated cells (B-IC) and to a lesser extent in CD principal cells and was also induced in connecting tubules. Similarly, we found that claudin-4 was expressed at low levels in normal human kidneys and was dramatically increased in CD cells of nephrotic human kidneys (focal and segmental glomerulosclerosis). In parallel, the expression of pendrin, which exchanges chloride for bicarbonates in B-IC, was decreased in nephrotic compared to control animals. However, the increase in claudin-4 expression observed in NS is likely independent of pendrin abundance. Increased claudin-4 abundance is coupled with increased ENaC-dependent sodium transport. Overexpression or silencing of claudin-4 in mCCDcl1 cells confirmed the preferential permeability of claudin-4 to chloride over sodium. ConclusionsThese results suggest that during NS, transcellular Cl-/HCO - transport decreases while paracellular chloride transport via claudin-4 may increase along the collecting system. Paracellular chloride permeability may constitute a chloride shunt that favors Na+ reabsorption and opposes K+ secretion along the CD in NS. Significance StatementNephrotic syndrome is a common disease characterized by massive proteinuria, hypoalbuminemia and edema due to renal sodium-chloride retention. We demonstrate for the first time an induction of claudin-4 expression indicating a partial shift from transcellular to paracellular chloride transport in the renal collecting system of nephrotic rodents. We confirmed the increased expression of claudin-4 in kidney biopsies of nephrotic patients, highlighting the translational significance of these results. Whether the paracellular pathway may represent a novel target to treat edema in nephrotic syndrome remains to be elucidated.

physiology↗

bioRxiv2019

Impaired renal gluconeogenesis is a major determinant of acute kidney injury associated mortality

Nature letterAcute Kidney Injury (AKI) is strongly associated with adverse outcome and mortality independently of the cause of renal damage1-3. The mechanisms determining the deleterious systemic effects of AKI are poorly understood and specific interventions, including optimization of renal replacement therapy, had a marginal effect on AKI-associated mortality in clinical trials4-8. The kidney contributes to up to 40% of systemic glucose production by gluconeogenesis during fasting and stress conditions, mainly synthesized from lactate in the proximal tubule9-12, rendering this organ a major systemic lactate disposal13. Whether kidney gluconeogenesis is impaired during AKI and how this might influence systemic metabolism remains unknown. Here we demonstrate that glucose production and lactate clearance are impaired during human AKI using renal arteriovenous catheterization in patients. Using single cell transcriptomics in mice and RNA sequencing in human biopsies, we show that glycolytic and gluconeogenetic pathways are modified during AKI in the proximal tubule specifically, explaining the metabolic alterations. We further demonstrate that impaired renal gluconeogenesis and lactate clearance during AKI are major determinants of systemic glucose and lactate levels in critically ill patients. Most importantly, altered glucose metabolism in AKI emerged as a major determinant of AKI-associated mortality. Thiamine supplementation restored renal glucose metabolism and substantially reduced AKI-associated mortality in intensive care patients. This study highlights an unappreciated systemic role of renal glucose and lactate metabolism in stress conditions, delineates general mechanisms explaining AKI-associated mortality and introduces a potential therapeutic intervention for a highly prevalent clinical condition with limited therapeutic options.

cell biology↗