Fangji Huangqi decoction ameliorates membranous nephropathy through the upregulation of BNIP3-mediated mitophagy.

ETHNOPHARMACOLOGICAL RELEVANCE: Fangji Huangqi Decoction (FJHQ), a traditional Chinese medicinal formula outlined in Zhang Zhongjing's "Jin Gui Yao Lue" during the Han Dynasty, is often used to treat conditions characterized by symptoms like edema and dysuria, including membranous nephropathy (MN). Despite its proven clinical effectiveness, the exact mechanisms through which FJHQ acts on MN remain elusive. AIM OF THE STUDY: This study aimed to investigate whether FJHQ enhances BNIP3-mediated mitophagy in podocytes by promoting BNIP3 expression and whether this improvement leads to the amelioration of MN. MATERIALS AND METHODS: In this study, by establishing passive Heymann nephritis (PHN) rats, an experimental rat model of MN induced by sheep anti-rat Fx1A serum, we evaluated the effects of FJHQ in vivo. In vitro experiments were carried out by treating primary podocytes with experimental rat serum. Furthermore, the potential mechanism by which FJHQ acts through BNIP3 was further examined by transfecting primary podocytes with the siRNA of BNIP3 or the corresponding control vector. RESULTS: After 4 weeks, significant kidney damage was observed in the rats in the model group, comparatively, FJHQ markedly decreased urine volume, 24-h urinary protein, blood urea nitrogen (BUN), creatinine (Scr), and increased serum total albumin (ALB). Histology showed that FJHQ caused significant improvements in glomerular hyperplasia, and IgG immune complex deposition in MN rats. JC-1 fluorescence labelling and flow cytometry analysis showed that FJHQ could significantly increase mitochondrial membrane potential in vivo. In the mitochondria of MN model rats, FJHQ was able to down-regulate the expression of P62 and up-regulate the expression of BNIP3, LC3B, and LC3 II/LC3 I, according to Western blot and immunofluorescence studies. Furthermore, FJHQ has been shown to significantly up-regulate mitochondrial membrane potential, down-regulate P62 expression in mitochondria, and up-regulate the expression of BNIP3, LC3B, and LC3 II/LC3 I in mitochondria at the cellular level. After the administration of the autophagy inhibitor chloroquine, the serum of rats treated with FJHQ further increased the expression of LC3 II/LC3 I in primary podocytes, showing higher autophagy flow. After the interference of BNIP3 in podocytes, the effect of FJHQ on mitochondrial membrane potential and autophagy-related proteins almost disappeared. CONCLUSION: FJHQ enhanced mitophagy in podocytes by promoting the expression of BNIP3, thereby contributing to the amelioration of MN. This work reveals the possible underlying mechanism by which FJHQ improves MN and provides a new avenue for MN treatment.

Exploring the mechanism of Dahuang-Tusizi drug pair in the treatment of diabetes nephropathy based on network pharmacology and immune infiltration analysis.

The study aimed to explore the key targets and molecular mechanisms of Dahuang-Tusizi drug pair (DTDP) in the treatment of diabetes nephropathy (DN) based on the GEO database by using network pharmacology combined with molecular docking and immune infiltration. The active components of the DTDP were screened using the Traditional Chinese Medicine Systems Pharmacology database and the Swiss Target Prediction database. The differential genes of DN were retrieved from GEO databases. Next, the intersecting targets of drug and disease were imported into the String database for protein-protein interactions network analysis, and the core targets were identified through topological analysis. Gene Ontology analysis and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed with the help of the Metascape database and gene set enrichment analysis database. Subsequently, molecular docking was performed to verify the binding activity of the key component and the key target. The Nephroseq V5 database was used to verify the clinical relevance of DN and core genes. Finally, the Using CIBERSORT Algorithm to analyze the immune Infiltration of DN Gene Chip. The network analysis showed that 25 active ingredients of DTDP were associated with 22 targets in DN. The key active ingredients (Sesamin, quercetin, EUPATIN, matrine, beta-sitosterol, isorhamnetin, etc.) and the core targets (JUN, EGF, CD44, FOS, KDR, CCL2, PTGS2, and MMP2) were further identified. Enrichment analysis revealed signaling pathways including TNF, MAPK, and IL-17 signaling pathway. Molecular docking results showed that there was a strong affinity between the key components and core targets. The results of immune infiltration found that the proportion of macrophages in DN tissues was significantly increased. Our findings demonstrated that the characteristics of DTDP in treating DN are "multiple components, multiple targets and multiple pathways." We predicted that DTDP may inhibit inflammation related pathways by regulating key genes, reducing macrophage infiltration. Thus, inhibiting inflammatory response to reduce glomerular damage and delay the development of DN.

Generating Human Glomeruli from Pluripotent Stem Cells for Disease Modelling and Drug Screening.

The functional unit of human kidney is the nephron. This structure is composed of a glomerulus, connected to a tubule that drains into a collecting duct. The cells which make up the glomerulus are critically important to the appropriate function of this specialised structure. Damage to glomerular cells, particularly the podocytes, is the primary cause of numerous kidney diseases. However, access to and the subsequent culture of human glomerular cells is limited. As such, the ability to generate human glomerular cell types from induced pluripotent stem cells (iPSCs) at scale has garnered great interest. Here, we describe a method to isolate, culture and study 3D human glomeruli from induced pluripotent stem cell (iPSC)-derived kidney organoids in vitro. These 3D glomeruli retain appropriate transcriptional profiles and can be generated from any individual. As isolated glomeruli, they have applicability for disease modelling and drug discovery.

L-glutamine supplementation reduced morphological damage in the renal glomerulus of rats with Walker-256 tumor

Purpose: To evaluate the effects of the experimental subcutaneous Walker-256 tumor and L-glutamine supplementation, an antioxidant, on the glomerular morphology of rats. Methods: Twenty Wistar rats were distributed into four groups (n = 5): control (C); control treated with 2% L-glutamine (CG); rats with Walker-256 tumor (WT); and rats with Walker-256 tumor treated with 2% L-glutamine (WTG). Renal histological samples were submitted to periodic acid-Schiff and Masson's Trichrome staining to analyze glomerular density, morphometry of glomerular components and glomerulosclerosis; and to immunohistochemistry for fibroblast growth factor-2 (FGF-2). Results: WT showed 50% reduction in body mass gain and cachexia index > 10%, while WTG demonstrated reduction in cachexia (p < 0.05). WT revealed reduction of glomerular density, increase in the glomerular tuft area, mesangial area, matrix in the glomerular tuft, decrease in the urinary space and synechia, and consequently higher glomerulosclerosis (p < 0.05). L-glutamine supplementation in the WTG improved glomerular density, and reduced glomerular tuft area, urinary space, mesangial area, and glomerulosclerosis compared to WT(p < 0.05). WT showed higher collagen area and FGF-2 expression compared to C (p < 0.05). WTG presented lower collagen fibers and FGF-2 expression compared to WT (p < 0.05). Conclusions: L-glutamine supplementation reduced cachexia and was beneficial for glomerular morphology of the rats, as well as it reduced kidney damage and improved the remaining glomeruli morphology.

Wogonin protects glomerular podocytes by targeting Bcl-2-mediated autophagy and apoptosis in diabetic kidney disease.

Diabetic kidney disease (DKD) is one of the microvascular complications of diabetes mellitus and a major cause of end-stage renal disease with limited treatment options. Wogonin is a flavonoid derived from the root of Scutellaria baicalensis Georgi, which has shown a potent renoprotective effect. But the mechanisms of action in DKD are not fully elucidated. In this study, we investigated the effects of wogonin on glomerular podocytes in DKD using mouse podocyte clone 5 (MPC5) cells and diabetic mice model. MPC5 cells were treated with high glucose (30 mM). We showed that wogonin (4, 8, 16 µM) dose-dependently alleviated high glucose (HG)-induced MPC5 cell damage, accompanied by increased expression of WT-1, nephrin, and podocin proteins, and decreased expression of TNF-α, MCP-1, IL-1ß as well as phosphorylated p65. Furthermore, wogonin treatment significantly inhibited HG-induced apoptosis in MPC5 cells. Wogonin reversed HG-suppressed autophagy in MPC5 cells, evidenced by increased ATG7, LC3-II, and Beclin-1 protein, and decreased p62 protein. We demonstrated that wogonin directly bound to Bcl-2 in MPC5 cells. In HG-treated MPC5 cells, knockdown of Bcl-2 abolished the beneficial effects of wogonin, whereas overexpression of Bcl-2 mimicked the protective effects of wogonin. Interestingly, we found that the expression of Bcl-2 was significantly decreased in biopsy renal tissue of diabetic nephropathy patients. In vivo experiments were conducted in STZ-induced diabetic mice, which were administered wogonin (10, 20, 40 mg · kg-1 · d-1, i.g.) every other day for 12 weeks. We showed that wogonin administration significantly alleviated albuminuria, histopathological lesions, and p65 NF-κB-mediated renal inflammatory response. Wogonin administration dose-dependently inhibited podocyte apoptosis and promoted podocyte autophagy in STZ-induced diabetic mice. This study for the first time demonstrates a novel action of wogonin in mitigating glomerulopathy and podocytes injury by regulating Bcl-2-mediated crosstalk between autophagy and apoptosis. Wogonin may be a potential therapeutic drug against DKD.

GlomSpheres as a 3D co-culture spheroid model of the kidney glomerulus for rapid drug-screening.

The glomerulus is the filtration unit of the kidney. Injury to any component of this specialised structure leads to impaired filtration and eventually fibrosis and chronic kidney disease. Current two and three dimensional (2D and 3D) models that attempt to recreate structure and interplay between glomerular cells are imperfect. Most 2D models are simplistic and unrepresentative, and 3D organoid approaches are currently difficult to reproduce at scale and do not fit well with current industrial drug-screening approaches. Here we report a rapidly generated and highly reproducible 3D co-culture spheroid model (GlomSpheres), better demonstrating the specialised physical and molecular structure of a glomerulus. Co-cultured using a magnetic spheroid formation approach, conditionally immortalised (CI) human podocytes and glomerular endothelial cells (GEnCs) deposited mature, organized isoforms of collagen IV and Laminin. We demonstrate a dramatic upregulation of key podocyte (podocin, nephrin and podocalyxin) and GEnC (pecam-1) markers. Electron microscopy revealed podocyte foot process interdigitation and endothelial vessel formation. Incubation with pro-fibrotic agents (TGF-ß1, Adriamycin) induced extracellular matrix (ECM) dysregulation and podocyte loss, which were attenuated by the anti-fibrotic agent Nintedanib. Incubation with plasma from patients with kidney disease induced acute podocyte loss and ECM dysregulation relative to patient matched remission plasma, and Nintedanib reduced podocyte loss. Finally, we developed a rapid imaging approach to demonstrate the model's usefulness in higher throughput pharmaceutical screening. GlomSpheres therefore represent a robust, scalable, replacement for 2D in vitro glomerular disease models.

Roles of glomerular endothelial hyaluronan in the development of proteinuria.

Vascular endothelial cells are covered with glycocalyx comprising heparan sulfate, hyaluronan, chondroitin sulfate, and associated proteins. Glomerular endothelial glycocalyx is involved in protecting against induction of proteinuria and structural damage, but the specific components in glycocalyx that represent therapeutic targets remain unclear. Anti-vascular endothelial growth factor (VEGF) therapy is associated with an increased risk of glomerular endothelial injury. This study investigated whether hyaluronan could provide a therapeutic target to protect against proteinuria. We conducted ex vivo and in vivo experiments to explore the effects of degrading glomerular hyaluronan by administering hyaluronidase and of supplementation with hyaluronan. We investigated hyaluronan expression using biotin-labeled hyaluronan-binding protein (HABP) in human kidney specimens or serum hyaluronan in endothelial injuries under inhibition of VEGF signaling. We directly demonstrated hyaluronan in glomerular endothelial layers using HABP staining. Ex vivo and in vivo experiments showed the development of proteinuria after digestion of hyaluronan in glomerular capillaries. Supplementation with hyaluronan after hyaluronidase treatment suppressed proteinuria. Mice in the in vivo study developed albuminuria after intraperitoneal injection of hyaluronidase with decreased glomerular hyaluronan and increased serum hyaluronan. In human kidneys with endothelial cell dysfunction and proteinuria due to inhibition of VEGF, glomerular expression of hyaluronan was reduced even in normal-appearing glomeruli. Serum hyaluronan levels were elevated in patients with pre-eclampsia with VEGF signaling inhibition. Our data suggest that hyaluronan itself plays crucial roles in preventing proteinuria and preserving the integrity of endothelial cells. Hyaluronan could provide a therapeutic target for preventing glomerular endothelial glycocalyx damage, including VEGF signaling inhibition.

Effects of calcitriol on peripheral endothelial progenitor cells and renal renovation in rats with chronic renal failure.

BACKGROUND: The role of calcitriol (1,25-dihydroxyvitamin D3 or 1,25-(OH)2D3) in physiological processes, such as anti-fibrosis, anti-inflammation, and immunoregulation is known; however, its role in the remodeling of the glomerular capillary endothelium in rats with chronic renal failure (CRF) remains unclear. METHODS: Here, we analyzed the role/number of endothelial progenitor cells (EPCs), renal function, and pathological alterations in rats with CRF, and compared the results before and after supplementation with calcitriol in vivo. RESULTS: Amongst the three experimental groups (sham group, CRF group, and calcitriol-treated group (0.03 µg/kg/d), we observed substantially elevated cell adhesion and vasculogenesis in vivo in the calcitriol-treated group. Additionally, lower levels of serum creatinine (Scr) and blood urea nitrogen (BUN) was recorded in the calcitriol-treated group than the CRF group (p > 0.05). Calcitriol treatment also resulted in an improvement in renal pathological injury. CONCLUSIONS: Thus, calcitriol could ameliorate the damage of glomerular arterial structural and renal tubules vascular network integrity, maybe through regulating the number and function of EPCs in the peripheral blood of CRF rats. Treatment with it may improve outcomes in patients with renal insufficiency or combined cardiac insufficiency. Calcitriol could ameliorate CRF-induced renal pathological injury and renal dysfunction by remodeling of the glomerular capillary endothelium, thus, improving the function of glomerular endothelial cells.

Tinospora cordifolia activates PPARγ pathway and mitigates glomerular and tubular cell injury in diabetic kidney disease.

BACKGROUND: Diabetic Kidney Disease (DKD) is a common complication of diabetes and a leading cause of end-stage renal disease progression. Therefore, therapeutic strategies are desirable to mitigate the progression of disease into more severe consequences. Hypothesis/Purpose:Tinospora cordifolia is a traditionally known antidiabetic plant; however, its effect against DKD remains unexplored. Therefore, in the present study, we assessed the efficacy and mechanism of action of Tinospora cordifolia extract (TC) against DKD. METHODS: The molecular interaction of the various phytoconstituents of TC with PPARγ were analyzed in silico. The effect of TC was studied on the viability, cell cycle, and gene expressions (PPARγ, TGFß, and αSMA) in high glucose treated NRK-52E and SV40 MES13 cells. Further, streptozotocin-induced diabetic rats were treated with TC for eight weeks, and the effects on different biochemical, histological and molecular parameters were studied. RESULTS: In silico analysis revealed the integration of various phytoconstituents of TC with PPARγ. It further increased PPARγ and decreased TGFß and αSMA expressions in NRK-52E and SV40 MES13 cells. In diabetic rats, TC improved the fasting blood glucose, serum urea, and creatinine levels. It also lowered the urine microalbumin and advanced glycation end products (AGEs) levels. Histopathological studies revealed the preventive effect of TC on degenerative changes, mesangial proliferation and glomerular hypertrophy. Further, it reduced the inflammation and fibrotic changes in the kidney tissue estimated by various markers. The kidney tissue and gene expression analysis revealed the augmented levels of PPARγ after TC treatment. CONCLUSION: In conclusion, TC exerted the protective effect against DKD by inhibiting inflammation and fibrogenesis through the activation of PPARγ dependent pathways.

Transcriptional Suppression of Diabetic Nephropathy with Novel Gene Silencer Pyrrole-Imidazole Polyamides Preventing USF1 Binding to the TGF-ß1 Promoter.

Upstream stimulatory factor 1 (USF1) is a transcription factor that is increased in high-glucose conditions and activates the transforming growth factor (TGF)-ß1 promoter. We examined the effects of synthetic pyrrole-imidazole (PI) polyamides in preventing USF1 binding on the TGF-ß1 promoter in Wistar rats in which diabetic nephropathy was established by intravenous administration of streptozotocin (STZ). High glucose induced nuclear localization of USF1 in cultured mesangial cells (MCs). In MCs with high glucose, USF1 PI polyamide significantly inhibited increases in promoter activity of TGF-ß1 and expression of TGF-ß1 mRNA and protein, whereas it significantly decreased the expression of osteopontin and increased that of h-caldesmon mRNA. We also examined the effects of USF1 PI polyamide on diabetic nephropathy. Intraperitoneal injection of USF1 PI polyamide significantly suppressed urinary albumin excretion and decreased serum urea nitrogen in the STZ-diabetic rats. USF1 PI polyamide significantly decreased the glomerular injury score and tubular injury score in the STZ-diabetic rats. It also suppressed the immunostaining of TGF-ß1 in the glomerulus and proximal tubules and significantly decreased the expression of TGF-ß1 protein from kidney in these rats. These findings indicate that synthetic USF1 PI polyamide could potentially be a practical medicine for diabetic nephropathy.

Adiponectin receptor agonist AdipoRon ameliorates renal inflammation in diet-induced obese mice and endotoxin-treated human glomeruli ex vivo.

AIMS/HYPOTHESIS: Chronic low-grade inflammation with local upregulation of proinflammatory molecules plays a role in the progression of obesity-related renal injury. Reduced serum concentration of anti-inflammatory adiponectin may promote chronic inflammation. Here, we investigated the potential anti-inflammatory and renoprotective effects and mechanisms of action of AdipoRon, an adiponectin receptor agonist. METHODS: Wild-type DBA/2J mice were fed with high-fat diet (HFD) supplemented or not with AdipoRon to model obesity-induced metabolic endotoxaemia and chronic low-grade inflammation and we assessed changes in the glomerular morphology and expression of proinflammatory markers. We also treated human glomeruli ex vivo and human podocytes in vitro with AdipoRon and bacterial lipopolysaccharide (LPS), an endotoxin upregulated in obesity and diabetes, and analysed the secretion of inflammatory cytokines, activation of inflammatory signal transduction pathways, apoptosis and migration. RESULTS: In HFD-fed mice, AdipoRon attenuated renal inflammation, as demonstrated by reduced expression of glomerular activated NF-κB p65 subunit (NF-κB-p65) (70%, p < 0.001), TNFα (48%, p < 0.01), IL-1ß (51%, p < 0.001) and TGFß (46%, p < 0.001), renal IL-6 and IL-4 (21% and 20%, p < 0.05), and lowered glomerular F4/80-positive macrophage infiltration (31%, p < 0.001). In addition, AdipoRon ameliorated HFD-induced glomerular hypertrophy (12%, p < 0.001), fibronectin accumulation (50%, p < 0.01) and podocyte loss (12%, p < 0.001), and reduced podocyte foot process effacement (15%, p < 0.001) and thickening of the glomerular basement membrane (18%, p < 0.001). In cultured podocytes, AdipoRon attenuated the LPS-induced activation of the central inflammatory signalling pathways NF-κB-p65, c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38-MAPK) (30%, 36% and 22%, respectively, p < 0.001), reduced the secretion of TNFα (32%, p < 0.01), and protected against podocyte apoptosis and migration. In human glomeruli ex vivo, AdipoRon reduced the LPS-induced secretion of inflammatory cytokines IL-1ß, IL-18, IL-6 and IL-10. CONCLUSIONS/INTERPRETATION: AdipoRon attenuated the renal expression of proinflammatory cytokines in HFD-fed mice and LPS-stimulated human glomeruli, which apparently contributed to the amelioration of glomerular inflammation and injury. Mechanistically, based on assays on cultured podocytes, AdipoRon reduced LPS-induced activation of the NF-κB-p65, JNK and p38-MAPK pathways, thereby impelling the decrease in apoptosis, migration and secretion of TNFα. We conclude that the activation of the adiponectin receptor by AdipoRon is a potent strategy to attenuate endotoxaemia-associated renal inflammation.

Curcumin analogue C66 attenuates obesity-induced renal injury by inhibiting chronic inflammation.

Obesity has been recognized as a major risk factor for the development of chronic kidney disease, which is accompanied by increased renal inflammation, fibrosis, and apoptosis. C66 is a curcumin derivative that exerts anti-inflammatory effects by inhibiting the JNK pathway and prevents diabetic nephropathy. The present study investigates the possible protective effect of C66 on high-fat diet (HFD)-induced obesity-related glomerulopathy. Mice were fed with HFD for 8 weeks while some were treated with C66 every 2 days for 11 weeks. The HFD-fed mice developed renal dysfunction, as well as elevated triglyceride and cholesterol. Kidneys of the HFD-fed mice showed marked glomerular injuries, apoptosis, and inflammation with markedly increased cytokine production. Interestingly, treating HFD-fed mice with C66 remarkably reversed these pathological changes via inhibiting inflammation and NF-κB/JNK activation. In cultured mesangial cells, Palmitic Acid was able to activate the pro-fibrotic mechanisms, apoptosis, inflammatory response, and NF-κB and JNK signaling pathways, all of which could be attenuated by C66 treatment. In all, we demonstrated that curcumin analogue C66 attenuates obesity-induced renal injury by inhibiting chronic inflammation and apoptosis via targeting NF-κB and JNK. Our data suggest that C66 can be potentially used to prevent obesity-associated renal diseases warranting future investigations.

Urinary coenzyme Q10 as a diagnostic biomarker and predictor of remission in a patient with ADCK4-associated Glomerulopathy: a case report.

BACKGROUND: AarF domain-containing kinase 4 (ADCK4)-associated glomerulopathy is a mitochondrial nephropathy caused by mutations in the ADCK4 gene, which disrupt coenzyme Q10 biosynthesis. CASE PRESENTATION: We report the case of a 25-year-old female patient with ADCK4-associated glomerulopathy presenting with proteinuria (and with no additional systemic symptoms). A known missense substitution c.737G > A (p.S246N) and a novel frameshift c.577-600del (p.193-200del) mutation were found. We followed the patient for 24 months during supplementation with coenzyme Q10 (20 mg/kg/d - 30 mg/kg/d) and describe the clinical course. In addition, we measured serum and urine coenzyme Q10 levels before and after coenzyme Q10 supplementation and compared them with those of healthy control subjects. The patient's urinary coenzyme Q10 to creatinine ratio was higher than that of healthy controls before coenzyme Q10 supplementation, but decreased consistently with proteinuria after coenzyme Q10 supplementation. CONCLUSIONS: Although the use of urinary coenzyme Q10 as a diagnostic biomarker and predictor of clinical remission in patients with ADCK4-associated glomerulopathy should be confirmed by larger studies, we recommend measuring urinary coenzyme Q10 in patients with isolated proteinuria of unknown cause, since it may provide a diagnostic clue to mitochondrial nephropathy.

Impact of passive heat acclimation on markers of kidney function during heat stress.

NEW FINDINGS: What is the central question of this study? Does passive heat acclimation alter glomerular filtration rate and urine-concentrating ability in response to passive heat stress? What is the main finding and its importance? Glomerular filtration rate remained unchanged after passive heat stress, and heat acclimation did not alter this response. However, heat acclimation mitigated the reduction in urine-concentrating ability and reduced the incidence of albuminuria in young healthy adults after passive heat stress. Collectively, these results suggest that passive heat acclimation might improve structural integrity and reduce glomerular permeability during passive heat stress. ABSTRACT: Little is known about the effect of heat acclimation on kidney function during heat stress. The purpose of this study was to determine the impact of passive heat stress and subsequent passive heat acclimation on markers of kidney function. Twelve healthy adults (seven men and five women; 26 ± 5 years of age; 72.7 ± 8.6 kg; 172.4 ± 7.5 cm) underwent passive heat stress before and after a 7 day controlled hyperthermia heat acclimation protocol. The impact of passive heat exposure on urine and serum markers of kidney function was evaluated before and after heat acclimation. Glomerular filtration rate, determined from creatinine clearance, was unchanged with passive heat stress before (pre, 133 ± 41 ml min-1 ; post, 127 ± 51 ml min-1 ; P = 0.99) and after (pre, 129 ± 46 ml min-1 ; post, 130 ± 36 ml min-1 ; P = 0.99) heat acclimation. The urine-to-serum osmolality ratio was reduced after passive heating (P < 0.01), but heat acclimation did not alter this response. In comparison to baseline, free water clearance was greater after passive heating before (pre, -0.86 ± 0.67 ml min-1 ; post, 0.40 ± 1.01 ml min-1 ; P < 0.01) but not after (pre, -0.16 ± 0.57 ml min-1 ; post, 0.76 ± 1.2 ml min-1 ; P = 0.11) heat acclimation. Furthermore, passive heating increased the fractional excretion rate of potassium (P < 0.03) but not sodium (P = 0.13) or chloride (P = 0.20). Lastly, heat acclimation reduced the fractional incidence of albuminuria after passive heating (before, 58 ± 51%; after, 8 ± 29%; P = 0.03). Collectively, these results demonstrate that passive heat stress does not alter the glomerular filtration rate. However, heat acclimation might improve urine-concentrating ability and filtration within the glomerulus.

Collapsing Focal Segmental Glomerulosclerosis and Acute Oxalate Nephropathy in a Patient With COVID-19: A Double Whammy.

As COVID-19 (coronavirus disease 2019) spreads across the world multiple therapeutic interventions have been tried to reduce morbidity and mortality. We describe a case of collapsing focal sclerosing glomerulosclerosis (FSGS) and acute oxalate nephropathy in a patient treated with high-dose intravenous vitamin C for severe COVID-19 infection. Collapsing FSGS has been described in patients with COVID-19 infection associated with APOL-1; however, this case had collapsing FSGS developing in low-risk heterozygous APOL-1 variant, and we postulate that the intensity of the COVID-19 cytokine storm overwhelmed the protective state of APOL-1 heterozygosity. This case illustrates the importance of assessing the risk and benefit of planned therapeutic interventions on a case-by-case basis especially when there are still so many unknowns in the management of COVID-19 infection. Strong consideration should be given for performing a renal biopsy in patients who develop multifactorial acute kidney injury.

Protective Role of Tangshen Formula on the Progression of Renal Damage in db/db Mice by TRPC6/Talin1 Pathway in Podocytes.

Tangshen Formula (TSF) is a Chinese Medicine formula that has been reported to alleviate proteinuria and protect renal function in humans and animals with diabetic kidney disease (DKD). However, little is known about its mechanism in improving proteinuria. The dysregulation of podocyte cell-matrix adhesion has been demonstrated to play an important role in the pathogenesis and progression of proteinuric kidney diseases including DKD. In the present study, the underlying protective mechanism of TSF on podocytes was investigated using the murine model of type 2 DKD db/db mice in vivo and advanced glycation end products (AGEs)-stimulated primary mice podocytes in vitro. Results revealed that TSF treatment could significantly mitigate reduction of podocyte numbers and foot process effacement, reduce proteinuria, and protect renal function in db/db mice. There was a significant increase in expression of transient receptor potential canonical channel 6 (TRPC6) and a decrease in expression of talin1 in podocytes of db/db mice. The results of AGEs-stimulated primary mice podocytes showed increased cell migration and actin-cytoskeleton rearrangement. Moreover, primary mice podocytes stimulated by AGEs displayed an increase in TRPC6-dependent Ca2+ influx, a loss of talin1, and translocation of nuclear factor of activated T cell (NFATC) 2. These dysregulations in mice primary podocytes stimulated by AGEs could be significantly attenuated after TSF treatment. 1-Oleoyl-2-acetyl-sn-glycerol (OAG), a TRPC6 agonist, blocked the protective role of TSF on podocyte cell-matrix adherence. In conclusion, TSF could protect podocytes from injury and reduce proteinuria in DKD, which may be mediated by the regulation of the TRPC6/Talin1 pathway in podocytes.

The yin and yang of retinoic acid signaling in kidney diseases.

Retinoic acid (RA) signaling is involved in various physiological and pathological conditions, including development, tumorigenesis, inflammation, and tissue damage and repair. In kidneys, the beneficial effect of RA has been reported in multiple disease models, such as glomerulosclerosis, renal fibrosis, and acute kidney injury. In this issue of the JCI, Chen et al. report a pathway activated by RA signaling that is mediated by the retinoic acid receptor responder protein 1 (RARRES1). Specifically, RARRES1, which is proteolytically cleaved to release the extracellular domain, was endocytosed by podocytes to induce apoptosis and glomerular dysfunction kidney disease. These findings unveil the contrasting aspects, a Janus face, of RA signaling that may guide its therapeutic use.

Ouabain regulates kidney metabolic profiling in rat offspring of intrauterine growth restriction induced by low-protein diet.

AIMS: Intrauterine growth restriction (IUGR) can increase the risk of hypertension and kidney disease at adulthood due to fetal programming. In our previous study, we found that supplementation with low concentration of ouabain during pregnancy could restore glomerulus numbers at birth, rescuing kidney development. However, the metabolic pattern of kidney in IUGR offspring and the effect of ouabain have not been evaluated. MAIN METHODS: In this study, based on GC-MS and LC-MS platforms, we used the protein restriction rat model to explore the molecular mechanisms of kidney damage induced by IUGR and the protective effect of ouabain. KEY FINDINGS: The results showed that malnutrition could induce IUGR in rat offspring at the 20th gestational day but ouabain treatment could partially reverse the body and kidney weight loss. Ouabain treatment could upregulate arginine, N-acetylornithine and carbamoyl phosphate as well as adenine nucleotide and guanine nucleotide downregulated by low-protein diet. Moreover, six metabolites were identified to be significantly correlated with fetal kidney weight, with 3 metabolites involved in arginine metabolism (arginine, N-acetylornithine, urea) and UDP-glucuronate correlated positively, while lysine and anthranilate correlated negatively. SIGNIFICANCE: The results suggested that the underlying mechanism of ouabain against renal maldevelopment involved the metabolic regulation, particularly the arginine metabolism, which played an important role in the development of fetal kidney.

[Effect of Guanxin Danshen Formulation on diabetic kidney disease in db/db mice through regulation of Nrf2 pathway].

Diabetic kidney disease(DKD) has become a primary cause of end-stage kidney disease, without any effective treatment available. In this study, we assessed the protective effect of Guanxin Danshen Formulation(GXDSF) on diabetic nephropathy in db/db mice. The db/m and db/db mice were randomly divided into 4 groups: control group, model group, metformin group, and GXDSF group. After 8 weeks' treatment with GXDSF, metformin or normal saline, the mice were sacrificed, and the blood and kidney tissues were collected for the further analysis. Compared with the model group, TG, TCH and LDL levels significantly decreased in the GXDSF group. The results from HE and PAS staining showed that db/db mice exhibited abnormal kidney tissues with increased glomerular volume, basement-membrane thickening and mesangial cell proliferation, which could be significantly alleviated by GXDSF treatment. GXDSF treatment also reduced serum creatinine and BUN. Meanwhile, GXDSF treatment markedly elevated GSH-PX levels, while reduced LDH and MDA levels in the kidney tissues. Western blot assay showed that GXDSF evidently up-regulated protein levels of ERα and p-Akt, and subsequently promoted HO-1 expression mediated by Nrf2. These data collectively indicated that GXDSF protects db/db mice against DN by regulating ERα and Nrf2-mediated HO-1 expression.

Vitamin D3 improves lipophagy-associated renal lipid metabolism and tissue damage in diabetic mice.

Oxidative stress and abnormal lipid metabolism in diabetes can trigger renal lipotoxicity, extending to diabetic nephropathy. Vitamin D3 has been known to be involved in lipid metabolism as well as insulin secretion or inflammation. Therefore, we hypothesized that vitamin D3 supplementation attenuated hyperglycemia-induced renal damage in diabetic mice. Diabetes was induced by a 40% kJ high-fat diet with 30 mg/kg body weight of streptozotocin by intraperitoneal injection twice in male C57BL/6J mice. Among diabetic mice (fasting blood glucose > 140 mg/dL), mice were supplemented with 300 ng/kg body weight of vitamin D3 dissolved in olive oil for 12 weeks. Normal control and diabetic control mice were orally administrated with olive oil as a vehicle. Normal control mice were fed with an AIN-93G diet during the experiment. Vitamin D3 supplementation in diabetic mice improved glucose intolerance and kidney function, demonstrated by diminishing glomerular areas. Vitamin D3 supplementation in diabetic mice significantly reduced triglycerides and low-density lipoprotein cholesterol in plasma as well as triglycerides and total cholesterol in the kidney. Furthermore, vitamin D3 supplementation attenuated lipid synthesis, oxidative stress, and apoptosis, accompanied by activation of ß-oxidation, antioxidant defense enzymes, and autophagy in diabetic mice. In conclusion, vitamin D3 supplementation ameliorates hyperglycemia-induced renal damage through the regulation of lipid metabolisms, oxidative stress, apoptosis, and autophagy in diabetes. Vitamin D3 could be a promising nutrient to weaken diabetic nephropathy.