Kidney Injury Molecule-1 Expression Research Articles

LncRNA MALAT1 mediated high glucose-induced HK-2 cell epithelial-to-mesenchymal transition and injury.

Epithelial-to-mesenchymal transition (EMT) and injury of tubular cells play critical roles in the pathogenesis of diabetic nephropathy (DN). lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) has been shown to be involved in DN progression. However, whether MALAT1 induces EMT and injury in tubular cells is unclear. Here, we investigated the effects of MALAT1 on human proximal tubular cells (HK-2 cells) and the underlying mechanism. We performed qPCR to detect MALAT1, E-cadherin, α-smooth muscle actin (α-SMA), kidney injury molecule 1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL). Additionally, we conducted Western blot analyses to measure E-cadherin, α-SMA, cyclin D1, c-Myc, and β-catenin in HK-2 cells cultured with normal glucose and high glucose (HG) and in transfected cells or cells treated with LiCl and DKK-1. The β-catenin localization was observed using immunofluorescence, and the protein levels of NGAL and KIM-1 were evaluated by ELISA. We found that HG-upregulated MALAT1 decreased E-cadherin and increased α-SMA, KIM-1, NGAL, cyclin D1, c-Myc, and β-catenin in HK-2 cells. LiCl exposure increased the expression of α-SMA but decreased that of E-cadherin on the base of knocking down MALAT1, and decreased NGAL and KIM-1 expression. DKK-1 showed the opposite effects. Our results suggested that upregulated MALAT1 induced EMT in HG-treated HK-2 cells through activating the Wnt/β-catenin pathway. However, MALAT1-mediated injury in HK-2 cells was not mediated by activation of the Wnt/β-catenin pathway. Our results indicate that MALAT1 might serve as a novel therapeutic target for suppressing the progression of DN.

Paricalcitol pretreatment attenuates renal ischemia/reperfusion injury by inhibiting p38 MAPK and activating PI3K/Akt signaling pathways

Abstract Objective This study aimed to investigate the renoprotective effects of paricalcitol, a synhetic vitamin D analog, through its possible roles on p38 MAPK and PI3K/Akt signaling pathways to prevent oxidative stress, inflammation and apoptosis during renal I/R. Materials and methods Total 20 kidney tissues of sham (n = 6), subjected to renal I/R bilaterally for 45 min ischemia followed by 24 h reperfusion (n = 7) and paricalcitol (0.3 μg/kg, ip) pretreated Wistar albino rats (n =7) were used in this study. Interstitial inflammation and active caspase-3 expression were evaluated histologically. TNF-α, IL-1β, kidney injury molecule-1 (KIM-1), MDA and SOD activity in kidneys were analysed biochemically. Furthermore, activation of p38 MAPK, PI3K/Akt signaling pathways and NFκB p65 were evaluated by western blot. Results Paricalcitol pretreatment significantly reduced interstitial inflammation during renal I/R, which was consistent with decreased tumor TNF-α, IL-1β, active caspase-3 and KIM-1 expression. Paricalcitol also reduced MDA level and attenuated the reduction of SOD activity in the kidney during I/R. Moreover, paricalcitol could suppress the p38 MAPK and NFκB p65, and also activate PI3K/Akt signaling pathway during renal I/R. Conclusion All these findings indicate that paricalcitol may be an effective practical strategy to prevent renal I/R injury.

Kidney Injury Molecule-1 Is Upregulated in Renal Lipotoxicity and Mediates Palmitate-Induced Tubular Cell Injury and Inflammatory Response.

Diabetic nephropathy is increasingly recognized as a major contributor to kidney failure in patients with obesity and type 2 diabetes. This study was designed to identify the molecular mediators of kidney injury associated with metabolic syndrome with or without hyperglycemia. We compared renal gene expression profiles in Zucker lean (ZL), Zucker obese (ZO), and Zucker diabetic (ZD) rats using cDNA microarray with quantitative verification of selected transcripts by real-time PCR. Compared to the 20-week-old ZL control (glucose: 110 ± 8 mg/dL), both prediabetic ZO (glucose: 157 ± 11 mg/dL) and diabetic ZD (glucose: 481 ± 37 mg/dL) rats displayed hyperlipidemia and kidney injury with a high degree of proteinuria. cDNA microarray identified 25 inflammation and injury-related transcriptomes whose expression levels were similarly increased in ZO and ZD kidneys. Among them, kidney injury molecule-1 (KIM-1) was found to be the most highly upregulated in both ZO and ZD kidneys. Immunofluorescence staining of kidney sections revealed a strong correlation between lipid overload and KIM-1 upregulation in proximal tubules of ZO and ZD rats. In cultured primary renal tubular epithelial cells (TECs), administration of saturated fatty acid palmitate resulted in an upregulation of KIM-1, osteopontin, and CD44, which was greatly attenuated by U0126, an inhibitor of extracellular signal-regulated kinase (ERK)1/2. Moreover, knockdown of KIM-1 by siRNA interference inhibited palmitate-induced cleaved caspase-3, osteopontin, and CD44 proteins in primary TECs. Our results indicate that KIM-1 expression is upregulated in renal lipotoxicity and may play an important role in fatty acid-induced inflammation and tubular cell damage in obesity and diabetic kidney disease.

Diagnostic roles of urinary kidney injury molecule 1 and soluble C5b-9 in acute tubulointerstitial nephritis.

Acute tubulointerstitial nephritis (ATIN) is a common cause of acute kidney injury characterized by inflammatory cells infiltrating in the interstitium. The present study aimed to explore noninvasive biomarkers that might indicate activity of pathological injuries and help direct treatment. Fifty-four patients with clinical-pathologically diagnosed ATIN from January 1, 2014, to June 30, 2016, at Peking University First Hospital were enrolled. Urine samples were collected on the morning of renal biopsy and assessed for urinary kidney injury molecule-1 (KIM-1) and urinary soluble C5b-9 (sC5b-9). Immunofluorescence staining for KIM-1 and C5b-9 was performed in biopsied kidney sections from ATIN cases. The clinical and pathological relevance of the two urinary biomarkers was analyzed. Both urinary KIM-1 and sC5b-9 values were significantly elevated in patients with ATIN compared with healthy controls. The urinary KIM-1 level positively correlated with urinary N-acetyl-β-d-glucosaminidase (r = 0. 542, P = 0.001) and the pathological tubular injury score (r = 0.469, P < 0.001), whereas the urinary sC5b-9 level was related to pathological activity scores for tubular injury (r = 0.413, P = 0.002), interstitial inflammation (r = 0.388, P = 0.004), and treatment response (r = 0.564, P < 0.001). Urinary KIM-1 tended to have better diagnostic value for tubular injury than urinary sC5b-9, whereas only urinary sC5b-9 was able to demonstrate severe interstitial inflammation. A combination of urinary KIM-1 and sC5b-9 had an area under the receiver-operating characteristic curve of 0.864 (95% confidence interval: 0.766-0.963, P < 0.001, sensitivity: 75%, specificity: 88%) for acute tissue injury in ATIN. KIM-1 expression was markedly increased in renal tubular cells in both ATIN and acute tubular necrosis conditions, whereas a significant upregulation of C5b-9 was only detected in the tubular cells and interstitial cells in ATIN cases. Urinary KIM-1 is a specific biomarker for renal tubular injury in ATIN, whereas urinary sC5b-9 is valuable in demonstrating severe interstitial inflammation. The combination of these two biomarkers helps identify patients at an acute injury stage and, therefore, might facilitate clinical evaluation and guide immunosuppressive therapy.

Abstract 4604: Kidney injury molecule-1 regulates metastasis in renal cell carcinoma

Abstract Over 30% of patients with renal cell carcinoma (RCC) present with metastases, with median survival of 2 years. Kidney injury molecule 1 (KIM-1) is a cell-surface glycoprotein expressed by &amp;gt;85% of RCC tumours and may serve as an early biomarker for RCC detection. Here we sought to determine if tumour KIM-1 plays a role in RCC cell extravasation and metastasis to lungs. Methods: We overexpressed KIM-1 in Renca cells (murine RCC) using stable transfection of an expression plasmid, or silenced endogenous KIM-1 in human 769-P and 786-O RCC cells using shRNA. We studied extravasation using the chorioallantoic membrane (CAM) model. We injected ~1x105 Renca or 769-P cells into blood vessels of chicken embryos (n=6), and measured percentage of cells that exited the capillary bed into surrounding spaces after 24 hours. To study lung metastasis, we injected ~5x105 Renca or 786-O cells intravenously through the tail vein of syngeneic BALB/c (n=10/group) or immune deficient Rag1-/- [BALB/c] (n=5/group) mice, and manually counted metastatic nodules in excised lungs after 17 days. Finally, we analyzed the publicly available Cancer Genome Atlas Illumina RNA-Seq dataset to determine if KIM-1 mRNA expression predicts overall survival in patients with clear cell RCC. Results: In CAM experiments, extravasation efficiency was significantly decreased in KIM-1pos 769-P cells compared to KIM-1neg 769-P cells (30.08% vs. 47.94%; p=0.0004), and in KIM-1pos Renca cells compared to KIM-1neg Renca cells (47.78% vs 60.73%; p=0.042). BALB/c mice injected with Kim-1pos Renca cells or Kim-1pos 786-O cells had significantly fewer lung metastases compared to mice injected with Kim-1neg Renca cells or Kim-1neg 786-O cells, respectively (257 vs 429, p=0.02; 131 vs 339 p=0.001). The inhibitory effect of KIM-1 expression in Renca and 786-O cells on numbers of lung metastases was similar in Rag1-/- mice, suggesting that the observed effects were not dependent on adaptive immunity. In the TCGA database, patients with the lowest vs. highest tertile of KIM-1 RCC expression has significantly higher mortality (unadjusted HR 1.82, 95% CI 1.23-2.70; p=0.0034). Conclusion: KIM-1 is a negative regulator of cell extravasation and inhibits the development of lung metastases in mice, and KIM-1 expression in human RCC may predict better survival. Deciphering the underlying mechanisms may lead to novel therapies. Citation Format: Jasper C. Lee, Marie A. Sarabusky, Audrey Champagne, Fabrice Lucien, Lakshman Gunaratnam. Kidney injury molecule-1 regulates metastasis in renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4604.

Attenuation of diabetic nephropathy by dietary fenugreek (Trigonella foenum-graecum) seeds and onion (Allium cepa) via suppression of glucose transporters and renin-angiotensin system.

The aim of this study was to determine the effects of dietary fenugreek (Trigonella foenum-graecum) seeds and onion on the hyperglycemia-stimulated glucose transporters and activation of renin-angiotensin system-mediated cascade of events leading to renal lesions in diabetic animals. The mechanistic aspects of nephroprotective influence of dietary fenugreek seeds (10%) and onion (3%) on diabetic renal lesions was investigated in streptozotocin diabetic rats. Renal damage was assessed by measuring proteinuria, enzymuria, expression of glucose transporters, renin-angiotensin system, and activities of polyol pathway enzymes. Diabetes resulted in an upregulation of glucose transporters in kidney tissue, which was countered by these dietary interventions. The upregulation of renal angiotensin-converting enzyme and its receptor was also countered by these dietary interventions. Dietary fenugreek and onion significantly reduced metabolites of polyol pathway, nitric oxide, and N-acetyl-β-d-glucosaminidase activity. Markers of podocyte damage in kidney (nephrin, podocin, and podocalyxin) and their urinary excretion were normalized along with downregulation of the expression of kidney injury molecule-1 by these dietary interventions. Dietary fenugreek and onion effectively countered the diabetes-induced structural abnormalities of renal tissue. Feeding fiber-rich fenugreek seeds and sulfur compounds-rich onion produced a blockade in glucose translocation and renin-angiotensin system in the early stage of diabetic nephropathy. This involved a downregulation of the expression of polyol pathway enzymes, partial restoration of the podocyte damage, revival of renal architecture and functional abnormality. The present study also suggested that these two dietary interventions offer a higher renoprotective influence when consumed together.

In vitro anti-nephrotoxic potential of Ammi visnaga, Petroselinum crispum, Hordeum vulgare, and Cymbopogon schoenanthus seed or leaf extracts by suppressing the necrotic mediators, oxidative stress and inflammation

BackgroundThe kidney is an essential organ required by the body to perform several important functions. Nephrotoxicity is one of the most prevailing kidney complications that result from exposure to an extrinsic or intrinsic toxicant, which increase the need for the acquisition of proper remedies. Recently, natural remedies are gaining great attention owed to the fact that they have fewer side effects than most conventional drugs.MethodsThe current study recorded a new therapeutic role of the well-known medicinal plants for kidney stones [Ammi visnaga (AVE), Petroselinum crispum (PCE), Hordeum vulgare (HVE), and Cymbopogon schoenanthus (CSE)]. Hence, the aqueous extracts of these plants examined against CCl4-induced toxicity in mammalian kidney (Vero) cells.ResultsThese extracts showed the presence of varying amounts of phenolic and triterpenoid compounds, as well as vitamin C. Owing to the antioxidant potential of these constituents, the extracts suppressed the CCl4-induced oxidative stress significantly (p < 0.05) by scavenging the reactive oxygen species and enhancing the cellular antioxidant indices. In addition, these extracts significantly (p < 0.05) reduced the CCl4-induced inflammation by inhibiting the gene expression of NF-кB, iNOS, and in turn the level of nitric oxide. Consequently, the morphological appearance of Vero cells, cellular necrosis, and the gene expression of kidney injury molecule-1 (a marker of renal injury) after these treatments were improved. The AVE improved CCl4-induced oxidative and inflammatory stress in Vero cells and showed a more potent effect than the commonly used alpha-Ketoanalogue drug (ketosteril) in most of the studied assays.ConclusionThus, the studied plant extracts, especially AVE can be considered as promising extracts in the management of nephrotoxicity and other chronic diseases associated with oxidative stress and inflammation.Graphical abstract

Protective effect of anisodamine in rats with glycerol-induced acute kidney injury

BackgroundAnisodamine is used for the treatment of reperfusion injury in various organs. In this study, we investigated the effectiveness and mechanisms of action of anisodamine in promoting recovery from glycerol-induced acute kidney injury (AKI).MethodsWe compared the protective effects of atropine and anisodamine in the rat model of glycerol-induced AKI. We examined signaling pathways involved in oxidative stress, inflammation and apoptosis, as well as expression of kidney injury molecule-1 (KIM-1). Renal injury was assessed by measuring serum creatinine and urea, and by histologic analysis. Rhabdomyolysis was evaluated by measuring creatine kinase levels, and oxidative stress was assessed by measuring malondialdehyde (MDA) and superoxide dismutase (SOD) levels in kidney tissues. Inflammation was assessed by quantifying interleukin 6 (IL-6) and CD45 expression. Apoptosis and necrosis were evaluated by measuring caspase-3 (including cleaved caspase 3) and RIP3 levels, respectively.ResultsGlycerol administration resulted in a higher mean histologic damage score, as well as increases in serum creatinine, urea, creatine kinase, reactive oxygen species (ROS), MDA, IL-6, caspase-3 and KIM-1 levels. Furthermore, glycerol reduced kidney tissue SOD activity. All of these markers were significantly improved by anisodamine and atropine. However, the mean histologic damage score and levels of urea, serum creatinine, creatine kinase, ROS and IL-6 were lower in the anisodamine treatment group compared with the atropine treatment group.ConclusionPretreatment with anisodamine ameliorates renal dysfunction in the rat model of glycerol-induced rhabdomyolytic kidney injury by reducing oxidative stress, the inflammatory response and cell death.

515-P: Mitochondrial AKT1 in Renal Tubules Is a Novel Modulator for the Development of Glomerulosclerosis and Subsequent Renal Failure

Diabetes increases the risk of renal ischemia/reperfusion injury (IRI). Recent evidence suggests that tubular dysfunction is associated with glomerular impairment, but its causal relationship is unclear. Renal tubules have abundant mitochondria; Akt is translocated into mitochondria upon IRI. To test the hypothesis that tubular mitochondrial Akt1 (mito-Akt) plays a protective role during IRI and subsequent renal failure, we have generated novel renal tubule-specific transgenic mice harboring inducible mitochondria-targeting dominant negative Akt1 (KMDAKT) or constitutively active Akt1 (KMCAKT) with the Cre-lox system. After KMDAKT mice were induced with tamoxifen (T) and subjected to IRI, histological analysis showed increased tubule injury index Jablonski score (p&amp;lt;0.04) and greater renal fibrosis as compared to the corn-oil (CO) injected mice (p&amp;lt;0.02). Kidney Injury Molecule-1 (KIM1), PAS-positive glomerulosclerosis, and serum creatinine were all increased (p&amp;lt;0.01) in the T-KMDAKT mice when compared to the CO mice 45-days post IRI. Renal inflammatory markers, including IL-1B, were also increased, suggesting inflammation played a role. Kaplan-Meier analysis showed much lower survival in the T-KAMDAKT mice post IRI than the CO mice (p&amp;lt;0.01). To study whether augmentation of tubular mito-Akt can protect against renal IRI, T-KMCAKT and CO-KMCAKT were subjected to renal IRI.T-KMCAKT mice showed an improved Jablonski score (p&amp;lt;0.02), less renal fibrosis (p&amp;lt;0.04), and lower KIM1 expression (p&amp;lt;0.02). T-KMCAKT mice exhibited less glomerulosclerosis and better survival (p&amp;lt;0.01). Summary: 1] tubular mito-Aktcritically modulated the outcomes of kidney IRI beyond renal tubules, 2] tubular mitochondria dysfunction causally triggered development of glomerulosclerosis during acute and chronic kidney failure, and 3] renal tubular mito-Akt, which is activated by insulin, may represent a novel therapeutic target for diabetic nephropathy. Disclosure H.Y. Lin: None. Y. Chen: None. A. Ta: None. H. Lee: None. Y. Chen: None. P.H. Wang: None.

Blocking pannexin-1 alleviates cisplatin-induced acute kidney injury in mice by reducing renal inflammatory cell infiltration

To investigate the effect of blocking pannexin-1 against acute kidney injury induced by cisplatin. Twenty-six male C57BL/6 mice aged 6-8 weeks were randomly divided into control group, cisplatin model (Cis) group and cisplatin + carbenoxolone treatment group (Cis + CBX). In Cis group and Cis + CBX group, the mice were injected intraperitoneally with 20 mg/kg of cisplatin and with CBX (20 mg/kg) at 30 min before and 24 and 48 h after cisplatin inhjection, respectively. All the mice were sacrificed at 72 h after cisplatin injection, and plasma and kidney samples were collected for testing mRNA and protein expression levels of pannexin-1 in the renal tissue using RT-qPCR and Western blotting and for detecting plasma creatinine and BUN levels; the pathological changes in the renal tissues were observed using Periodic Acid-Schiff staining. The expression of kidney injury molecule 1 (KIM-1) was examined using immunohistochemistry and the mRNA expressions of KIM-1 and neutrophil gelatinase- related lipid transport protein (NGAL) were detected by RT-qPCR to evaluate the injuries of the renal tubules. The infiltration of F4/80-positive macrophages and CD4-positive T cells were observed by immunofluorescence. In the in vitro experiment, human proximal tubule epithelial cell line HK-2 was stimulated with 50 μmol/L cisplatin to establish a cell model of acute kidney injury, and the mRNA and protein expressions of pannexin-1 were detected by RT-qPCR and Western blotting at 4, 6, 12, 18 and 24 h after the stimulation. Compared with the control mice, the cisplatin-treated mice showed significantly up-regulated protein levels (P &lt; 0.05) and mRNA levels (P &lt; 0.005) of pannexin-1 in the kidney tissue. Cisplatin stimulation also caused significant increases in the protein levels (P &lt; 0.005) and mRNA levels (P &lt; 0.005) of pannexin-1 in cultured HK-2 cells. Compared with cisplatin-treated mice, the mice treated with both cisplatin and the pannexin-1 inhibitor CBX showed obviously lessened kidney pathologies and milder renal tubular injuries with significantly reduced plasma BUN and Scr levels (P &lt; 0.01), expressions of KIM-1 and NGAL in the kidney (P &lt; 0.05), and infiltration of F4/80-positive macrophages (P &lt; 0.01) and CD4- positive T cells (P &lt; 0.05) in the kidney tissues. In cisplatin induced acute kidney injury mice model, Pannexin-1 expression is up-regulated in the kidneys tissue, and blocking pannexin-1 alleviates the acute kidney injury via reducing renal inflammatory cell infiltration.

TGFβ1 Regulates KIM‐1 and Caveolin‐1 Expression through the Smad3 and ERK1/2 Signaling Pathways in Renal Cancer Cells

Kidney injury molecule‐1 (KIM‐1) is a type I transmembrane glycoprotein that is rapidly upregulated at the gene and protein level following various types of injury to the kidney. KIM‐1 expression is increased not only in acute and chronic kidney injury diseases but also in renal cell carcinoma. It may play an important role in carcinoma process. Caveolin‐1, the principal component of caveolae, is regarded as an important inhibitor of multiple signaling molecules. The cytokine transforming growth factor‐β1 (TGF‐β1) has been extensively studied in tumor biology and is believed to serve a variety of functions in tumor progression. In this study, we investigated the regulatory mechanism of TGF‐β1 on KIM‐1 and caveolin‐1 expression in 769‐P cells, a human renal cell adenocarcinoma cell line. Western blot analysis indicated that TGF‐β1 treatment resulted in a downregulation of KIM‐1 and an upregulation of caveolin‐1 in 769‐P cells. Specific knockdown of Smad3 with siRNAs significantly increased basal KIM‐1 expression and attenuated TGF‐β1‐induced KIM‐1 down regulation, which was associated with increased activation of extracellular signal‐regulated kinase (ERK) 1/2 and signal transducer and activator of transcription 3 (STAT3) signaling pathways. Interestingly, pre‐treatment of 769‐P cells with ERK inhibitor U0126 abolished TGF‐β1‐induced caveolin‐1 upregulation and partially restored KIM‐1 protein level. We also observed a significant decrease in KIM‐1 in 769‐P cells administered with caveolin‐1 scaffolding domain peptides. Taken together, our data demonstrate that TGF‐β1 may differentially regulate KIM‐1 and caveolin‐1 expression in renal cancer cells via both Smad3 and ERK1/2 signaling pathways.Support or Funding InformationNIH SC1DK112151; NIH/NCRR/RCMI 8G12MD007602 &amp; 8U54MD007588This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Protective effects of curcumin on diabetic nephropathy via attenuation of kidney injury molecule 1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) expression and alleviation of oxidative stress in rats with type 1 diabetes.

Objective(s):One of the serious complications of Type1 diabetes (T1D) is diabetic nephropathy, which is accompanied with overexpression of kidney injury molecule 1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) and enhanced oxidative stress. The present study was conducted to examine the protective effect of curcumin on the expression of KIM-1, NGAL genes and oxidative damage in the kidney of T1D rats. Materials and Methods:Thirty-six adult male rats were divided into 6 groups (n=6). The control and T1D groups received treatment with curcumin or without it (80 and 130 mg/kg, respectively). After 60 days of treatment, using spectrophotometric methods, biochemical factors and oxidative stress markers were measured. Gene expression of KIM-1 and NGAL was evaluated using quantitative PCR. Also, plasma and urine levels of these two proteins were assayed by the ELISA kit. Results:Diabetes caused a significant increase in the levels of creatinine, FBS, uric acid, urea, and creatinine in the serum, which were attenuated after the administration of curcumin. There was a significant reduction in the values of creatinine, uric acid, and urea in urine in the diabetic group whereas in the rats treated with curcumin, these values were normalized to the normal level (especially in 130 mg/kg). Curcumin administration had a significant role in modulation of serum lipid profile, and it was shown to decrease the kidney and urinary expression levels of KIM-1 and NGAL genes and improve oxidative toxic stress in the kidney tissues.Conclusion:Curcumin can play a protective role in reducing the unpleasant consequences of diabetic nephropathy.

Enhancing regeneration after acute kidney injury by promoting cellular dedifferentiation in zebrafish.

ABSTRACTAcute kidney injury (AKI) is a serious disorder for which there are limited treatment options. Following injury, native nephrons display limited regenerative capabilities, relying on the dedifferentiation and proliferation of renal tubular epithelial cells (RTECs) that survive the insult. Previously, we identified 4-(phenylthio)butanoic acid (PTBA), a histone deacetylase inhibitor (HDI), as an enhancer of renal recovery, and showed that PTBA treatment increased RTEC proliferation and reduced renal fibrosis. Here, we investigated the regenerative mechanisms of PTBA in zebrafish models of larval renal injury and adult cardiac injury. With respect to renal injury, we showed that delivery of PTBA using an esterified prodrug (UPHD25) increases the reactivation of the renal progenitor gene Pax2a, enhances dedifferentiation of RTECs, reduces Kidney injury molecule-1 (Kim-1) expression, and lowers the number of infiltrating macrophages. Further, we found that the effects of PTBA on RTEC proliferation depend upon retinoic acid signaling and demonstrate that the therapeutic properties of PTBA are not restricted to the kidney but also increase cardiomyocyte proliferation and decrease fibrosis following cardiac injury in adult zebrafish. These studies provide key mechanistic insights into how PTBA enhances tissue repair in models of acute injury and lay the groundwork for translating this novel HDI into the clinic.This article has an associated First Person interview with the joint first authors of the paper.

Mucin 1 Regulates KIM‐1 Function Following Ischemic Renal Injury

Kidney injury molecule‐1 (KIM‐1) is a type I transmembrane glycoprotein that is rapidly induced after kidney injury in the proximal tubule (PT). The ectodomain of KIM‐1 is cleaved by a disintegrin and metalloproteinase domain 17 (ADAM17) and thereby constitutively shed into the urine providing a sensitive biomarker for kidney injury. It was reported recently that a transcription factor STAT3 is phosphorylated by extracellular signal‐regulated kinases 1 and 2 (ERK1/2) and/or checkpoint kinase 1 (ChK1) following kidney injury and thereby upregulates KIM‐1. KIM‐1 also has an anti‐inflammatory role as it mediates phagocytosis of apoptotic and necrotic cells (efferocytosis) following kidney injury. However, the accelerated shedding of KIM‐1 regulated by p38 MAPK blocks efferocytosis as the excess soluble KIM‐1 acts as a decoy to cell‐associated KIM‐1. Mucin 1 (MUC1 in humans, and Muc1 in mice) is a transmembrane glycoprotein found primarily in the distal nephron that is also induced in the PT following kidney injury. We previously published data showing that Muc1 plays a protective role during ischemia‐reperfusion injury (IRI) by stabilizing both HIF‐1a and b‐catenin. More recently, using our hanging‐weight protocol of 20 min ischemia and 48 h recovery, we observed a significant two‐fold higher level of urinary KIM‐1 as well as more severe kidney injury in Muc1 KO mice when compared to wild‐type (WT) littermates. We also found that MUC1 and KIM‐1 are co‐localized in human kidney proximal tubule using immunofluorescence microscopy. Based on these findings, we tested the hypothesis that Muc1 limits kidney injury and enhances recovery during IRI by modulating the pathways known to regulate PT KIM‐1 activity. Immunoblots of kidney tissue revealed that levels of active ERK1/2 were significantly higher in Muc1 KO mice when compared to WT littermates. Though the levels of active p38 MAPK were significantly induced following kidney injury, there was no significant difference between Muc1 KO mice and WT littermates. Using an in vitro cell culture model where MDCK cells were stably transfected with KIM‐1 and transiently transfected with MUC1 or empty vector, we observed a reduction in KIM‐1 expression levels in the presence of MUC1. We also observed in our preliminary data that KIM‐1 shedding was enhanced after treating MDCK cells with PMA (a PKC activator that used to enhance ectodomain shedding of surface proteins such as those mediated by ADAM17) only in the absence of MUC1. As Muc1 is also a substrate for ADAM17, we also hypothesize that the absence of the competing Muc1 substrate after AKI in the Muc1 KO mice, could account for the accelerated shedding of KIM‐1 and consequently more severe kidney injury. These results support the likelihood that Muc1 regulates KIM‐1 function by regulating both its expression and shedding following kidney injury.Support or Funding InformationThis work was supported by the National Institutes of Health (K01 DK109038, and P30‐DK‐079307), Pittsburgh Center for Kidney Research and Dialysis Clinics, Inc. (DCI).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Nifedipine Modulates Renal Lipogenesis via the AMPK-SREBP Transcriptional Pathway.

Lipid accumulation in renal cells has been implicated in the pathogenesis of obesity-related kidney disease, and lipotoxicity in the kidney can be a surrogate marker for renal failure or renal fibrosis. Fatty acid oxidation provides energy to renal tubular cells. Ca2+ is required for mitochondrial ATP production and to decrease reactive oxygen species (ROS). However, how nifedipine (a calcium channel blocker) affects lipogenesis is unknown. We utilized rat NRK52E cells pre-treated with varying concentrations of nifedipine to examine the activity of lipogenesis enzymes and lipotoxicity. A positive control exposed to oleic acid was used for comparison. Nifedipine was found to activate acetyl Coenzyme A (CoA) synthetase, acetyl CoA carboxylase, long chain fatty acyl CoA elongase, ATP-citrate lyase, and 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG CoA) reductase, suggesting elevated production of cholesterol and phospholipids. Nifedipine exposure induced a vast accumulation of cytosolic free fatty acids (FFA) and stimulated the production of reactive oxygen species, upregulated CD36 and KIM-1 (kidney injury molecule-1) expression, inhibited p-AMPK activity, and triggered the expression of SREBP-1/2 and lipin-1, underscoring the potential of nifedipine to induce lipotoxicity with renal damage. To our knowledge, this is the first report demonstrating nifedipine-induced lipid accumulation in the kidney.

Hesperidin opposes the negative impact of cyclophosphamide on mice kidneys

The present investigation examined the prospective nephroprotective effect of hesperidin (HSN) in mice challenged with a single i.p. injection of cyclophosphamide (CPE) at a dose of 200 mg/kg. HSN (100 and 200 mg/kg/day, p.o.) was given for 10 days, starting 5 days prior to CPE administration. HSN significantly reduced the CPE-induced increments of serum creatinine and cystatin C. HSN also significantly reduced malondialdehyde, nitric oxide, Bax/Bcl-2 ratio, and caspase-3, and significantly raised total antioxidant capacity, and interleukin-10/tumor necrosis factor-α ratio in kidneys of mice received CPE. In addition, HSN significantly prevented the histopathological injury, and kidney injury molecule-1 expression in kidneys of mice given CPE. It was concluded that HSN guarded against nephrotoxic effect of CPE in mice by tackling oxidative/nitrative stress, inflammation, and apoptosis.

Dual actions on gout flare and acute kidney injury along with enhanced renal transporter activities by Yokuininto, a Kampo medicine

BackgroundProlonged hyperuricemia is associated with kidney disease or gouty arthritis. Whether Yokuininto, a commercially available Kampo medicine that has been used for osteoarthritis or rheumatoid arthritis, can exhibit anti-hyperuricemic and inflammatory effects remains elusive. In the present study, Yokuininto exerts multiple homeostatic action on serum uric acid (sUA) levels by blocking pro-inflammatory cytokine activities and inducing uricosuric function with anti-renal injury functions.MethodsThe sUA was measured in potassium oxonate (PO)-administered mice. Renal transporter uptake assays were performed using HEK293 cells overexpressing OAT1, OCT2 or OAT3, MDCKII cells overexpressing BCRP, and Xenopus oocytes overexpressing OAT3 or URAT1. Immunoblot and ELISA assays were performed to detect the molecules (OAT3, GLUT9, XO, NGAL, KIM-1 and IL-1α) in various human kidney cell lines. Cell viability analysis was performed to evaluate the cytotoxicity of Yokuininto [Ephedrine + pseudoephedrine 21.94%; Paeoniflorin 35.40% and Liquiritin 16.21% relatively measured by the ratios (HR-MS2 intensity / HR-MS1 intensity)].ResultsYokuininto (300 mg/kg) significantly reduced sUA by approximately 44% compared to that of PO-induced mice. The OAT3 levels were decreased in PO-induced hyperuricemic condition, whereas the GLUT9 transporter levels were markedly increased. However, PO did not alter the levels of URAT1. Yokuininto significantly inhibited the lipopolysaccharide (LPS)-induced secretion of IL-1α by approximately 63.2% compared to the LPS-treated macrophages. In addition, Yokuininto inhibited nitric oxide synthesis by approximately 33.7 (500 µg/mL) and 64.6% (1000 µg/mL), compared to that of LPS-treated macrophages. Yokuininto markedly increased xanthine oxidase inhibition activity. Furthermore, interleukin-1α (IL-1α), a pro-inflammatory cytokine, elevated neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) activities in LLC-PK1 cells. Expression of renal inflammatory biomarkers, NGAL and KIM-1, was reduced under the Yokuininto treatment by 36.9 and 72.1%, respectively.ConclusionsThose results suggest that Yokuininto may suppress inflammation and protect against kidney dysfunction in hyperuricemia. The present findings demonstrated that Yokuininto lowered sUA through both increased uric acid excretion and decreased uric acid production. Our results may provide a basis for the protection of prolonged hyperuricemia-associated kidney injury with uric acid-lowering agents such as Yokuininto.

Blockade of ERK1/2 by U0126 alleviates uric acid-induced EMT and tubular cell injury in rats with hyperuricemic nephropathy.

Extracellular signal-regulated kinases 1 and 2 (ERK1/2) are serine/threonine kinases and function as regulators of cellular proliferation and differentiation. Recently, we demonstrated that inhibition of ERK1/2 alleviates the development and progression of hyperuricemia nephropathy (HN). However, its potential roles in uric acid-induced tubular epithelial-mesenchymal transition (EMT) and tubular epithelial cell injury are unknown. In this study, we showed that hyperuricemic injury induced EMT as characterized by downregulation of E-cadherin and upregulation of vimentin and Snail1 in a rat model of HN. This was coincident with epithelial cells arrested at the G2/M phase of cell cycle, activation of Notch1/Jagged-1 and Wnt/β-catenin signaling pathways, and upregulation of matrix metalloproteinase-2 (MMP-2) and MMP-9. Administration of U0126, a selective inhibitor of ERK1/2, blocked all these responses. U0126 was also effective in inhibiting renal tubular cell injury, as shown by decreased expression of lipocalin-2 and kidney injury molecule-1 and active forms of caspase-3. U0126 or ERK1/2 siRNA can inhibit tubular cell EMT and cell apoptosis as characterized with decreased expression of cleaved caspase-3. Moreover, ERK1/2 inhibition suppressed hyperuricemic injury-induced oxidative stress as indicated by decreased malondialdehyde and increased superoxide dismutase. Collectively, ERK1/2 inhibition-elicited renal protection is associated with inhibition of EMT through inactivation of multiple signaling pathways and matrix metalloproteinases, as well as attenuation of renal tubule injury by enhancing cellular resistance to oxidative stress.

Fisetin supplementation prevents high fat diet-induced diabetic nephropathy by repressing insulin resistance and RIP3-regulated inflammation.

Obesity-related renal disease is related to caloric excess promoting deleterious cellular responses. However, a full understanding of the molecular mechanisms involved in progressive kidney disease, as well as a therapeutic strategy, is still absent. Fisetin (FIS), as a natural flavonoid, possesses various bioactivities in a number of disease models. However, its role in obesity-associated kidney injury is still unclear and requires elucidation. In our study, an obesity animal model was established using C57BL/6 mice fed with a normal chow diet (NCD) or high fat diet (HFD) for 16 weeks with or without FIS administration (20, 40 or 80 mg kg-1). Our results indicated that chronic HFD feeding led to a significant body weight gain in mice compared to the normal control group, accompanied by a marked insulin resistance and glucose intolerance, whereas FIS treatment exerted prominently protective effects. In addition, FIS significantly attenuated HFD-induced histological alterations in renal tissue samples. Moreover, FIS treatment down-regulated expression of kidney injury molecule-1 (KIM-1), and up-regulated nephrin and podocin expression levels in the kidneys of HFD-fed mice, improving their renal dysfunction. After HFD feeding, mice treated with FIS exhibited a decrease in phosphorylated IRS1Ser307, and an increase in phosphorylated glycogen synthase kinase 1 (IRS1Tyr608), AKT, forkhead box protein O1 (FOXO1) and glycogen synthase kinase (GSK)-3β. Furthermore, FIS administration markedly restrained the inflammatory response in the kidneys of HFD-challenged mice, as evidenced by the reduced pro-inflammatory cytokines, tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), IL-1β and IL-18, which was attributed to the blockage of nuclear factor κB (NF-κB) signaling. Importantly, FIS-treated obese mice exerted a remarkable decrease in RIP3 expressions in the kidneys compared to obese mice in the absence of FIS, along with an evident reduction in the NOD-like receptor protein 3 (NLRP3), an apoptosis-associated speck-like protein containing a Caspase recruitment domain (ASC) and Caspase-1. The protective effects of FIS against HFD-induced renal injury were verified in vitro using palmitate (PAL)-treated HK2 cells, an immortalized proximal tubule epithelial cell line from the adult human kidney. In summary, our results supported the notion that FIS functions as a promising agent to improve insulin resistance and inflammatory response against metabolic stress-induced renal injury.

Kidney injury molecule-1 expression predicts structural damage and outcome in histological acute tubular injury

Background: A few studies have shown that urinary kidney injury molecule-1 (uKIM-1) levels are increased in acute kidney injury (AKI); however, the correlation between uKIM-1 and histological tubular injury, which is considered to be the gold standard for evaluating renal damage and predicting prognosis, is still unclear. We performed this study to determine whether the predicted value of uKIM-1 is correlated with renal KIM-1 (tKIM-1) expression and tissue damage in AKI patients.Methods: This retrospective study recruited 14 healthy individuals and 27 biopsy-proven acute tubular injury (ATI) patients. uKIM-1 and plasma KIM-1 (sKIM-1) levels were measured by ELISA, and tKIM-1 expression was evaluated by immunohistochemistry.Results: Elevated levels of urinary, plasma, and renal KIM-1 were found in ATI patients. The uKIM-1 concentration was positively correlated with tKIM-1 expression and reflected the severity of renal histological injury. The outcome of ATI was associated with uKIM-1 expression: the ATI patients with higher uKIM-1 levels had an increased potential for an incomplete recovery of renal function during follow-up. Additionally, the level of KIM-1, regardless of source, was negatively related to the eGFR, and ROC curve analysis revealed that the ROC-AUC was 0.923 (p = 0.000) for the diagnosis of ATI based on a combination of high uKIM-1 and sKIM-1 levels.Conclusion: The uKIM-1 level corresponds with the severity of renal histological damage and can be a potential reliable predictor of adverse renal outcomes in ATI patients. Moreover, combining uKIM-1 and sKIM-1 can increase the sensitivity and specificity of the diagnosis of severe ATI.