Diabetic Kidney Injury Research Articles

Oral administration of herbal oligonucleotide drug JGL-sRNA-h7 ameliorates hyperglycemia in db/db mice and beagle dogs.

Type 2 diabetes mellitus is a prevalent metabolic disease, posing a considerable threat to public health. Oligonucleotide drugs have proven to be a promising field of therapy for the diseases. In this study, we reported that a herbal small RNA (sRNA), JGL-sRNA-h7 (B34735529, F1439.L002444.A11), could exhibit potent hypoglycemic effects by targeting glucose-6-phosphatase. Oral administration of sphingosine (d18:1)-JGL-sRNA-h7 bencaosomes ameliorated hyperglycemia and diabetic kidney injury better than metformin in db/db mice. Furthermore, glucose tolerance was also improved in sphingosine (d18:1)-JGL-sRNA-h7 bencaosomes-treated beagle dogs. Our study indicates that JGL-sRNA-h7 could be a promising hypoglycemic oligonucleotide drug.

Urinary Podocin as a Noninvasive Marker of Kidney Injury in New-Onset Diabetes after Kidney Transplantation

Urinary Podocin as a Noninvasive Marker of Kidney Injury in New-Onset Diabetes after Kidney Transplantation

Integrating network pharmacology and experimental validation to decipher the pharmacological mechanism of DXXK in treating diabetic kidney injury

Diabetes mellitus (DM) is a chronic metabolic disease that is highly susceptible to kidney injury. Di’ao XinXueKang capsules (DXXK) is a novel Chinese herbal medicine that has been used in clinical trials for the therapy of DM and kidney disease, but the underlying pharmacological mechanism remains unclear. This study aims to integrate network pharmacology, molecular docking and in vivo experiments to explore the potential mechanisms of DXXK in the treatment of diabetic kidney injury. The chemical constituents of DXXK were extracted from the ETCM and Batman-TCM databases, and then evaluated for their pharmacological activity via the Swiss ADME platform. Multiple disease databases were searched and integrated for DM-related targets. Overlapping targets were then collected to construct a protein–protein interaction (PPI) network. KEGG and GO enrichment analyses were performed based on the Metascape database, and molecular docking was performed using AutoDock Vina software. The main components in DXXK were analyzed by HPLC. The results of network pharmacology and molecular docking were validated in an animal model of DM induced by the combination of a high-fat diet (HFD) and streptozotocin (STZ). We screened and obtained 7 ingredients and identified dioscin, protodioscin, and pseudoprotodioscin as the major components of DXXK by HPLC. A total of 2,216 DM-related pathogenic genes were obtained from DrugBank, GeneCards, OMIM, and DisGeNET databases. KEGG and GO enrichment analyses indicated that the TGF-beta signaling pathway is a critical pathway associated with DM therapy. Molecular docking revealed that the ingredients in DXXK bind to the pivotal targets TGFβ1, Smad2, and Smad3. In diabetic mice, we found that DXXK alleviated diabetic symptoms, lowered blood glucose, improved insulin tolerance, and modulated lipid metabolism. Furthermore, DXXK attenuated renal lesions and fibrosis by downregulating TGFβ1, Smad2, and Smad3. Collectively, our results suggest that DXXK has the potential to regulate glucolipid metabolism in DM, and it may serve as a viable therapeutic option for renoprotection by inhibiting of the TGF-β1/Smad2/3 pathway.

Quercetin ameliorates diabetic kidney injury in rats by inhibiting the HMGB1/RAGE/NF-κB signaling pathway

To explore the effect of quercetin on renal inflammation and cell apoptosis in diabetic rats and its possible mechanisms. Twenty-four adult male SD rats were randomized equally into normal control group, high-glucose and high-fat feeding group, streptozotocin (STZ) -induced diabetic model group, and quercetin treatment (daily dose 100 mg/kg) group. Pathological changes of the renal tissues of the rats were observed with HE staining, serum inflammatory factor levels were determined with ELISA, and renal expression of NF‑κB was observed by immunohistochemistry. Fast blood glucose (FBG), serum levels of triglyceride (TG), BUN, and Scr, and 24-h urine protein content of the rats were measured, and renal expressions of HMGB1, RAGE, NF‑κB, Bax, Bcl-2, and caspase-3 were detected with Western blotting. The diabetic rats showed significantly increased levels of FBG, TG, BUN, and Scr, renal hypertrophy index, 24-h urinary protein content, serum IL-1β, IL-6 and TNF-α levels and renal expressions HMGB1, RAGE, NF‑κB, Bax, and caspase-3 with decreased renal expression of Bcl-2. All these changes were significantly alleviated by quercetin treatment of the rats. Quercetin can ameliorate kidney injury in diabetic rats possibly by inhibiting the HMGB1/RAGE/NF-κB inflammatory signaling pathway to reduce renal inflammation and renal cell apoptosis.

Ethyl Acetate Fractions of Salvia miltiorrhiza Bunge (Danshen) Crude Extract Modulate Fibrotic Signals to Ameliorate Diabetic Kidney Injury.

Diabetic nephropathy, a leading cause of end-stage renal disease, accounts for significant morbidity and mortality. It is characterized by microinflammation in the glomeruli and myofibroblast activation in the tubulointerstitium. Salvia miltiorrhiza Bunge, a traditional Chinese medicine, is shown to possess anti-inflammatory and anti-fibrotic properties, implying its renal-protective potential. This study investigates which type of component can reduce the damage caused by diabetic nephropathy in a single setting. The ethyl acetate (EtOAc) layer was demonstrated to provoke peroxisome proliferator-activated receptor (PPAR)-α and PPAR-γ activities in renal mesangial cells by dual luciferase reporter assay. In a high glucose (HG)-cultured mesangial cell model, the EtOAc layer substantially inhibited HG-induced elevations of interleukin-1β, transforming growth factor-β1 (TGF-β1), and fibronectin, whereas down-regulated PPAR-γ was restored. In addition, among the extracts of S. miltiorrhiza, the EtOAc layer effectively mitigated TGF-β1-stimulated myofibroblast activation. The EtOAc layer also showed a potent ability to attenuate renal hypertrophy, proteinuria, and fibrotic severity by repressing diabetes-induced proinflammatory factor, extracellular matrix accumulation, and PPAR-γ reduction in the STZ-induced diabetes mouse model. Our findings, both in vitro and in vivo, indicate the potential of the EtOAc layer from S. miltiorrhiza for future drug development targeting diabetic nephropathy.

ESRRA modulation by empagliflozin mitigates diabetic tubular injury via mitochondrial restoration

BackgroundThe protection of the diabetic kidney by Empagliflozin (EMPA) is attributed to its interaction with the sodium glucose cotransporter 2 located on proximal tubular epithelial cells (PTECs). Estrogen-related receptor α (ESRRA), known for its high expression in PTECs and association with mitochondrial biogenesis, plays a crucial role in this process. This study aimed to explore the impact of ESRRA on mitochondrial mass in diabetic tubular injury and elucidate the mechanism underlying the protective effects of EMPA. MethodsMitochondrial changes in PTECs of 16-week-old diabetic mice were assessed using transmission electron microscopy (TEM) and RNA-sequences. In vivo, EMPA administration was carried out in db/db mice for 8 weeks, while in vitro experiments involved modifying ESRRA expression in HK2 cells using pcDNA-ESRRA or EMPA. ResultsEvaluation through TEM revealed reduced mitochondrial mass and swollen mitochondria in PTECs, whereas no significant changes were observed under light microscopy. Analysis of RNA-sequences identified 110 downregulated genes, including Esrra, associated with mitochondrial function. Notably, ESRRA overexpression rescued the loss of mitochondrial mass induced by high glucose (HG) in HK2 cells. EMPA treatment ameliorated the ultrastructural alterations and mitigated the downregulation of ESRRA both in db/db mice and HG-treated HK2 cells. ConclusionThe diminished expression of ESRRA is implicated in the decline of mitochondrial mass in PTECs during the early stages of diabetes, highlighting it as a key target of EMPA for preventing the progression of diabetic kidney injury.

Astaxanthin attenuates diabetic kidney injury through upregulation of autophagy in podocytes and pathological crosstalk with mesangial cells

Objectives: Astaxanthin (ATX) is a strong antioxidant drug. This study aimed to investigate the effects of ATX on podocytes in diabetic nephropathy and the underlying renal protective mechanism of ATX, which leads to pathological crosstalk with mesangial cells.Methods: In this study, diabetic rats treated with ATX exhibited reduced 24-h urinary protein excretion and decreased blood glucose and lipid levels compared to vehicle-treated rats. Glomerular mesangial matrix expansion and renal tubular epithelial cell injury were also attenuated in ATX-treated diabetic rats compared to control rats.Results: ATX treatment markedly reduced the α-SMA and collagen IV levels in the kidneys of diabetic rats. Additionally, ATX downregulated autophagy levels. In vitro, compared with normal glucose, high glucose inhibited LC3-II expression and increased p62 expression, whereas ATX treatment reversed these changes. ATX treatment also inhibited α-SMA and collagen IV expression in cultured podocytes. Secreted factors (vascular endothelial growth factor B and transforming growth factor-β) generated by high glucose-induced podocytes downregulated autophagy in human mesangial cells (HMCs); however, this downregulation was upregulated when podocytes were treated with ATX.Conclusions: The current study revealed that ATX attenuates diabetes-induced kidney injury likely through the upregulation of autophagic activity in podocytes and its antifibrotic effects. Crosstalk between podocytes and HMCs can cause renal injury in diabetes, but ATX treatment reversed this phenomenon.

PDK4-mediated Nrf2 inactivation contributes to oxidative stress and diabetic kidney injury

Diabetic kidney disease (DKD) is often featured with redox dyshomeostatis. Pyruvate dehydrogenase kinase 4 (PDK4) is the hub for DKD development. However, the mechanism by which PDK4 mediates DKD is poorly understood. The current work aimed to elucidate the relationship between PDK4 and DKD from the perspective of redox manipulation. Oxidative stress was observed in the human proximal tubular cell line (HK-2 cells) treated with a high concentration of glucose and palmitic acid (HGL). The mechanistic study showed that PDK4 could upregulate Kelch-like ECH-associated protein 1 (Keap1) in HGL-treated HK-2 cells through the suppression of autophagy, resulting in the depletion of nuclear factor erythroid 2-related factor 2 (Nrf2), the master regulator of redox homeostasis. At the cellular level, pharmacological inhibition or genetic knockdown of PDK4 could boost Nrf2, followed by the increase of a plethora of antioxidant enzymes and ferroptosis-suppression enzymes. Meanwhile, the inhibition or knockdown of PDK4 remodeled iron metabolism, further mitigating oxidative stress and lipid peroxidation. The same trend was observed in the DKD mice model. The current work highlighted the role of PDK4 in the development of DKD and suggested that PDK4 might be a promising target for the management of DKD.

Not too much, not too little—just the right amount: the story of YAP in the podocyte

Chen etal. identify dysregulation of the transcriptional activator Yes-associated protein in the podocytes of diabetic mouse and human kidneys. Podocyte Yes-associated protein deficiency led to downregulation of the key transcription factor Wilms' tumor 1, and worsened podocyte injury in a mouse model of diabetic kidney injury. Yes-associated protein may therefore play a critical role in diabetic podocyte injury via regulation of Wilms' tumor 1 expression.

Research Progress on Podocyte Pyroptosis in Diabetic Nephropathy.

Pyroptosis is a recently discovered type of lytic-programmed cell necrosis. The process involves cells assembling an inflammasome and cleaving gasdermin (GSDM) to trigger the release of pro-inflammatory cytokines that eventually induce inflammatory cell death. Diabetic nephropathy (DN) is a microvascular complication of diabetes mellitus, which leads to end-stage renal disease. Podocyte damage or loss is an important feature of diabetic kidney injury. Pyroptosis involvement in podocyte injury is closely associated with DN progression, manifesting as increased renal fibrosis, glomerulosclerosis, and tubular injury. The study aims to elucidate the mechanism of pyroptosis and summarize the pathways and potential inhibitors related to pyroptosis activation in DN podocytes. We undertook a search of bibliographic databases for peer-reviewed research literature on various aspects of pyroptosis. Multiple different pathways mediate podocyte pyroptosis to promote DN progression. Inhibition of pyroptosis can reduce podocyte damage and improve renal function in DN, suggesting that pyroptosis may help identify potential new therapeutic targets for DN treatment.

Unraveling the role of natriuretic peptide clearance receptor (NPR3) in glomerular diseases

Natriuretic peptides (NPs) are cardio-derived hormones that have a crucial role in maintaining cardiovascular homeostasis. Physiological effects of NPs are mediated by binding to natriuretic peptide receptors 1 and 2 (NPR1/2), whereas natriuretic peptide receptor 3 (NPR3) acts as a clearance receptor that removes NPs from the circulation. Mouse studies have shown that local NP-signaling in the kidney glomerulus is important for the maintenance of renal homeostasis. In this study we examined the expression of NPR3 in kidney tissue and explored its involvement in renal physiology and disease by generating podocyte-specific knockout mice (NPR3podKO) as well as by using an NPR3 inhibitor (NPR3i) in rodent models of kidney disease. NPR3 was highly expressed by podocytes. NPR3podKO animals showed no renal abnormalities under healthy conditions and responded similarly to nephrotoxic serum (NTS) induced glomerular injury. However, NPR3i showed reno-protective effects in the NTS-induced model evidenced by decreased glomerulosclerosis and reduced podocyte loss. In a ZSF1 rat model of diabetic kidney injury, therapy alone with NPR3i did not have beneficial effects on renal function/histology, but when combined with losartan (angiotensin receptor blocker), NPR3i potentiated its ameliorative effects on albuminuria. In conclusion, these results suggest that NPR3 may contribute to kidney disease progression.

Irbesartan ameliorates diabetic kidney injury in db/db mice by restoring circadian rhythm and cell cycle.

Irbesartan has been widely used in the clinical treatment of diabetic kidney disease (DKD). However, the molecular mechanism of its delay of DKD disease progression has not been fully elucidated. The aim of the present study was to investigate the mechanism of irbesartan in the treatment of DKD. C57BL/KsJ db/db mice were randomly divided into the model group and irbesartan-treated group. After treatment with irbesartan for 12 weeks, the effects on blood glucose, body weight, 24-h urinary albumin, and renal injuries were evaluated. Microarray was used to determine the differentially expressed genes (DEGs) in the renal cortex of mice. |Log FC| <0.5 and false discovery rate (FDR) <0.25 were set as the screening criteria. Kyoto Encyclopedia of Genes and Genomes (KEGG), gene ontology (GO), protein-protein interaction (PPI) network and modules, and microRNA (miRNA)-DEGs network analysis were applied to analyze the DEGs. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the results of microarray. The present study demonstrated irbesartan could significantly improve the renal function in db/db mice through decreasing 24-h urinary albumin and alleviating the pathological injury of kidney. Irbesartan may affect the expression of numerous kidney genes involved in circadian rhythm, cell cycle, micoRNAs in cancer, and PI3K-AKT signaling pathway. In the miRNA-DEGs network, miR-1970, miR-703, miR-466f, miR-5135, and miR-132-3p were the potential targets for irbesartan treatment. The validation test confirmed that key genes regulating circadian rhythm (Arntl, Per3, and Dbp) and cell cycle (Prc1, Ccna2, and Ccnb2) were restored in db/db mice on treatment with Irbesartan. Generally, irbesartan can effectively treat DKD by regulating the circadian rhythm and cell cycle. The DEGs and pathways identified in the study will provide new insights into the potential mechanisms of irbesartan in the treatment of DKD.

Irbesartan ameliorates diabetic kidney injury in db/db mice by restoring circadian rhythm and cell cycle.

Irbesartan has been widely used in the clinical treatment of diabetic kidney disease (DKD). However, the molecular mechanism of its delay of DKD disease progression has not been fully elucidated. The aim of the present study was to investigate the mechanism of irbesartan in the treatment of DKD. C57BL/KsJ db/db mice were randomly divided into the model group and irbesartan-treated group. After treatment with irbesartan for 12 weeks, the effects on blood glucose, body weight, 24-h urinary albumin, and renal injuries were evaluated. Microarray was used to determine the differentially expressed genes (DEGs) in the renal cortex of mice. |Log FC| <0.5 and false discovery rate (FDR) <0.25 were set as the screening criteria. Kyoto Encyclopedia of Genes and Genomes (KEGG), gene ontology (GO), protein-protein interaction (PPI) network and modules, and microRNA (miRNA)-DEGs network analysis were applied to analyze the DEGs. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the results of microarray. The present study demonstrated irbesartan could significantly improve the renal function in db/db mice through decreasing 24-h urinary albumin and alleviating the pathological injury of kidney. Irbesartan may affect the expression of numerous kidney genes involved in circadian rhythm, cell cycle, micoRNAs in cancer, and PI3K-AKT signaling pathway. In the miRNA-DEGs network, miR-1970, miR-703, miR-466f, miR-5135, and miR-132-3p were the potential targets for irbesartan treatment. The validation test confirmed that key genes regulating circadian rhythm (Arntl, Per3, and Dbp) and cell cycle (Prc1, Ccna2, and Ccnb2) were restored in db/db mice on treatment with Irbesartan. Generally, irbesartan can effectively treat DKD by regulating the circadian rhythm and cell cycle. The DEGs and pathways identified in the study will provide new insights into the potential mechanisms of irbesartan in the treatment of DKD.

Activin A Contribution to Diabetic Kidney Disease Injury and Effects of Activin A Antagonism In-Vitro

Diabetic kidney disease (DKD) is the worldwide leader in end-stage kidney failure and has limited treatment options. Cellular senescence abundance and inflammation contribute to DKD pathogenesis. We previously demonstrated that activin A, an inflammatory mediator of pro-fibrotic kidney injury and cellular senescence, is increased in DKD and correlates with DKD injury and kidney function. We hypothesized that activin A contributes to DKD injury causing pro-fibrotic, pro-inflammatory, and cellular senescence effects in vitro, and that antagonism of activin A is achieved with follistatin. An in vitro model of DKD injury was applied with high-glucose (HG) and transforming growth factor-β (TGFβ) exposure for 24 hours in U-937-derived macrophages and renal epithelial (HK2) cells. Prior to exposure, U-937 cells were converted to M0 macrophages with phorbol myristate acetate (PMA). To examine the potential of reducing activin A release by DKD injured cells, follistatin, an activin A antagonist, was added to the media of cells at the time of injury for 24 hours. Additionally, an activin A neutralizing antibody was added to the collected supernatant of DKD injured cells. Activin A, senescence (p16), pro-fibrotic (collagen I), and pro-inflammatory (monocyte chemoattractant protein [MCP]-1, tumor necrosis factor [TNF]-alpha, interleukin [IL]-6) markers were measured through qPCR, ELISA (activin A), and immunofluorescence staining (activin A). DKD injury in renal epithelial cells increased protein expression of activin A, increased gene expression of activin A, p16, and collagen I, but did not significantly increase MCP-1 expression at 24 hour exposure (Figure 1). Furthermore, DKD injury led to increased activin A release in conditioned medium vs. control renal epithelial cells. Administration of follistatin reduced activin A release by renal epithelial cells. Application of neutralizing antibody reduced activin A levels in collected medium after cell injury. After DKD injury in U-937 derived macrophages, activin A gene expression was increased. Injured macrophages had increased gene expression of TNF-alpha and IL-6, demonstrating a pro-inflammatory phenotype. In conclusion, diabetic kidney injury increases activin A release, inflammation markers, and senescence markers in kidney cells and macrophages, therein contributing to downstream effects that further propagate disease. As shown, follistatin antagonism reduces activin A release by injured cells. Additional studies are needed to explore activin A as a promising therapeutic target and follistatin as a possible treatment in DKD. NIH 5TL1TR002380-07, AG076537, DK123492, DK109134. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Theaflavin-3,3'-Digallate Protects Liver and Kidney Functions in Diabetic Rats by Up-Regulating Circ-ITCH and Nrf2 Signaling Pathway.

Theaflavin-3,3'-digallate (TFDG) in black tea has a strong antioxidant capacity. However, its effect on diabetic liver and kidney injury and the underlying mechanisms remain unclear. In the present study, our findings indicated that TFDG administration effectively lowers the fasting blood glucose and serum lipid concentrations and enhances the functionality and cellular architecture of the liver and kidney in rats with diabetes. The data also showed that TFDG mitigates oxidative harm in the liver and kidney of rats afflicted with diabetes. Additionally, metformin combined with TFDG was significantly more effective in reducing blood glucose and oxidative stress. Further studies suggested that TFDG upregulates the Nrf2 signal pathway and circ-ITCH (hsa_circ_0001141) expression. Silencing of circ-ITCH by transfection of the interfering plasmid apparently reduces the effects of TFDG on the Nrf2 signal pathway and oxidative stress in high-glucose-treated hepatic and renal cells. In conclusion, the present study highlights the great potential of TFDG in ameliorating diabetic liver and kidney injury by up-regulating circ-ITCH to promote the Nrf2 signal pathway and provides a potential option for the prevention and treatment of diabetic complications.

Endothelial CXCR2 deficiency attenuates renal inflammation and glycocalyx shedding through NF-κB signaling in diabetic kidney disease

BackgroundThe incidence of diabetic kidney disease (DKD) continues to rapidly increase, with limited available treatment options. One of the hallmarks of DKD is persistent inflammation, but the underlying molecular mechanisms of early diabetic kidney injury remain poorly understood. C-X-C chemokine receptor 2 (CXCR2), plays an important role in the progression of inflammation-related vascular diseases and may bridge between glomerular endothelium and persistent inflammation in DKD.MethodsMultiple methods were employed to assess the expression levels of CXCR2 and its ligands, as well as renal inflammatory response and endothelial glycocalyx shedding in patients with DKD. The effects of CXCR2 on glycocalyx shedding, and persistent renal inflammation was examined in a type 2 diabetic mouse model with Cxcr2 knockout specifically in endothelial cells (DKD-Cxcr2eCKO mice), as well as in glomerular endothelial cells (GECs), cultured in high glucose conditions.ResultsCXCR2 was associated with early renal decline in DKD patients, and endothelial-specific knockout of CXCR2 significantly improved renal function in DKD mice, reduced inflammatory cell infiltration, and simultaneously decreased the expression of proinflammatory factors and chemokines in renal tissue. In DKD conditions, glycocalyx shedding was suppressed in endothelial Cxcr2 knockout mice compared to Cxcr2L/L mice. Modulating CXCR2 expression also affected high glucose-induced inflammation and glycocalyx shedding in GECs. Mechanistically, CXCR2 deficiency inhibited the activation of NF-κB signaling, thereby regulating inflammation, restoring the endothelial glycocalyx, and alleviating DKD.ConclusionsTaken together, under DKD conditions, activation of CXCR2 exacerbates inflammation through regulation of the NF-κB pathway, leading to endothelial glycocalyx shedding and deteriorating renal function. Endothelial CXCR2 deficiency has a protective role in inflammation and glycocalyx dysfunction, suggesting its potential as a promising therapeutic target for DKD treatment.

Prostaglandin Transporter and Dipeptidyl Peptidase-4 as New Pharmacological Targets in the Prevention of Acute Kidney Injury in Diabetes: An In Vitro Study.

The probability of acute kidney injury (AKI) is higher in septic diabetic patients, which is associated with, among other factors, proximal tubular cell (PTC) injury induced by the hypoxic/hyperglycemic/inflammatory microenvironment that surrounds PTCs in these patients. Here, we exposed human PTCs (HK-2 cells) to 1% O2/25 mM glucose/inflammatory cytokines with the aim of studying the role of prostaglandin uptake transporter (PGT) and dipeptidyl peptidase-4 (DPP-4, a target of anti-hyperglycemic agents) as pharmacological targets to prevent AKI in septic diabetic patients. Our model reproduced two pathologically relevant mechanisms: (i) pro-inflammatory PTC activation, as demonstrated by the increased secretion of chemokines IL-8 and MCP-1 and the enhanced expression of DPP-4, intercellular leukocyte adhesion molecule-1 and cyclo-oxygenase-2 (COX-2), the latter resulting in a PGT-dependent increase in intracellular prostaglandin E2 (iPGE2); and (ii) epithelial monolayer injury and the consequent disturbance of paracellular permeability, which was related to cell detachment from collagen IV and the alteration of the cell cytoskeleton. Most of these changes were prevented by the antagonism of PGE2 receptors or the inhibition of COX-2, PGT or DPP-4, and further studies suggested that a COX-2/iPGE2/DPP-4 pathway mediates the pathogenic effects of the hypoxic/hyperglycemic/inflammatory conditions on PTCs. Therefore, inhibitors of PGT or DPP-4 ought to undergo testing as a novel therapeutic avenue to prevent proximal tubular damage in diabetic patients at risk of AKI.

Excess iron accumulation mediated senescence in diabetic kidney injury.

Cellular senescence and iron accumulation were separately observed in diabetic nephropathy (DN). Limited evidence supports that iron was significantly accumulated in senescent cells. We aimed to explore whether iron is involved in the pathogenesis role of senescence in DN.Renal cells were treated with high glucose (HG, 35 mM) for 10 or 15 days, and DN mice were induced by high-fat diet and streptozotocin. Gene ontology enrichment, gene set enrichment analysis analysis, β-galactosidase staining, 5-ethynyl-2-deoxyuridine staining, and western blot depicted the upregulated senescence pathway in vitro and in vivo of DN. Lactate dehydrogenase (LDH) release was increased by HG and reversed by p16/p21 knockdown, and the supernatant of HG-treated cells caused increased LDH release from normal cells. Iron metabolism-related protein expression was disordered after HG exposure concomitant with senescence. Ferric ammonium citrate (50 μM) upregulated gamma-H2A.X variant histone andincreased the senescence markers in HG-treated cells. The treatment of deferoxamine (0.5 μM) had the opposite effect. Compared to the non-DN individual, increased ferritin and senescence markers were verified in DN mice and patients, and the co-localization of ferritin and senescence markers was observed by immunofluorescence. These results suggested that accumulated iron was correlated with aggravated DNA damage and accelerated senescence, and revealed the role of iron in the cellular senescence of diseases.

HMGN1 down-regulation in the diabetic kidney attenuates tubular cells injury and protects against renal inflammation via suppressing MCP-1 and KIM-1 expression through TLR4.

Renal tubular injury, accompanied by damaging inflammation, has been identified to drive diabetic kidney disease (DKD) toward end-stage renal disease. However, it is unclear how damage-associated molecular patterns (DAMPs) activate innate immunity to mediate tubular epithelial cell (TEC) injury, which in turn causes with subsequent sterile inflammation in diabetic kidneys. High mobility group nucleosome-binding protein 1 (HMGN1) is a novel DAMP that contributes to generating the innate immune response. In this study, we focused on determining whether HMGN1 is involved in DKD progression. Streptozotocin (STZ)-induced diabetic mice model was established. Then we downrergulated HMGN1 expression in kidney with or without HMGN1 administration. The renal dysfunction and morphological lesions in the kidneys were evaluated. The expressions of KIM-1, MCP-1, F4/80, CD68, and HMGN1/TLR4 signaling were examined in the renal tissue. In vitro, HK2 cells were exposed in the high glucose with or without HMGN1, and further pre-incubated with TAK242 was applied to elucidate the underlying mechanism. We demonstrated that HMGN1 was upregulated in the tubular epithelial cells of streptozotocin (STZ)-induced type 1 and type 2 diabetic mouse kidneys compared to controls, while being positively correlated with increased TLR4, KIM-1, and MCP-1. Down-regulation of renal HMGN1 attenuated diabetic kidney injury, decreased the TLR4, KIM-1, and MCP-1 expression levels, and reduced interstitial infiltrating macrophages. However, these phenotypes were reversed after administration of HMGN1. In HK-2 cells, HMGN1 promoted the expression of KIM-1 and MCP-1 via regulating MyD88/NF-κB pathway; inhibition of TLR4 effectively diminished the in vitro response to HMGN1. Our study provides novel insight into HMGN1 signaling mechanisms that contribute to tubular sterile injury and low-grade inflammation in DKD. The study findings may help to develop new HMGN1-targeted approaches as therapy for immune-mediated kidney damage rather than as an anti-infection treatments.

Inhibition of transcriptional coactivator YAP Impairs the expression and function of transcription factor WT1 in diabetic podocyte injury

Podocyte injury and loss are hallmarks of diabetic nephropathy (DN). However, the molecular mechanisms underlying these phenomena remain poorly understood. YAP (Yes-associated protein) is an important transcriptional coactivator that binds with various other transcription factors, including the TEAD family members (nuclear effectors of the Hippo pathway), that regulate cell proliferation, differentiation, and apoptosis. The present study found an increase in YAP phosphorylation at S127 of YAP and a reduction of nuclear YAP localization in podocytes of diabetic mouse and human kidneys, suggesting dysregulation of YAP may play a role in diabetic podocyte injury. Tamoxifen-inducible podocyte-specific Yap gene knockout mice (YappodKO) exhibited accelerated and worsened diabetic kidney injury. YAP inactivation decreased transcription factor WT1 expression with subsequent reduction of Tead1 and other well-known targets of WT1 in diabetic podocytes. Thus, our study not only sheds light on the pathophysiological roles of the Hippo pathway in diabetic podocyte injury but may also lead to the development of new therapeutic strategies to prevent and/or treat DN by targeting the Hippo signaling pathway.