scholarly journals Early Elimination of Uremic Toxin Ameliorates AKI to CKD Transition

2021 ◽  
Author(s):  
Jia Huang Chen ◽  
Chia-Ter Chao ◽  
Jenq-Wen Huang ◽  
Kuan-Yu Hung ◽  
Shing-Hwa Liu ◽  
...  
Keyword(s):  
Er Stress ◽  
Renal Fibrosis ◽  
Epithelial Mesenchymal Transition ◽  
Early Stage ◽  
Ischemia Reperfusion ◽  
Organic Anion ◽  
Organic Anion Transporter ◽  
Uremic Toxin ◽  
Mesenchymal Transition ◽  
Anion Transporter

Acute kidney injury (AKI)-related fibrosis is a major driver of chronic kidney disease (CKD) development. Aberrant kidney recovery after AKI is multifactorial and still unclear. The accumulation of indoxyl sulfate (IS), a protein-bound uremic toxin, has been identified as a detrimental factor of renal fibrosis. However, the mechanisms underlying IS-related aberrant kidney recovery after AKI is still unknown. The study aims to elucidate the effects of IS in the pathogenesis of AKI to CKD transition. Our results showed that serum IS started to accumulate associated with the downregulation of tubular organic anion transporter, but not observed in the small-molecule uremic toxins of the unilateral ischemia-reperfusion injury without a contralateral nephrectomy model(UIRI). Serum IS is positively correlated with renal fibrosis and ER stress-related protein expression induction in the UIRI with a contralateral nephrectomy model (UIRI+Nx). To evaluate the effects of IS in the AKI to CKD transition, we administered indole, a precursor of IS, at the early stage of UIRI. Our results demonstrated IS potentiates renal fibrosis, senescence-associated secretory phenotype (SASP), and activation of ER, which is attenuated by synergistic AST-120 administration. Furthermore, we clearly demonstrated that IS exposure potentiated hypoxia-reperfusion (H/R) induced G2/M cell cycle arrest, epithelial-mesenchymal transition, and aggravated ER stress induction in vitro. Finally, the ER chemical chaperon, 4-PBA, successfully reversed the above-mentioned AKI to CKD transition. Taken together, early IS elimination in the early stage of AKI is likely to be a useful strategy in the prevention or treatment of the AKI to CKD transition.

scholarly journals Indoxyl Sulfate Contributes to mTORC1-Induced Renal Fibrosis via The OAT/NADPH Oxidase/ROS Pathway

Toxins ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 909
Author(s):  
Takehiro Nakano ◽  
Hiroshi Watanabe ◽  
Tadashi Imafuku ◽  
Kai Tokumaru ◽  
Issei Fujita ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Renal Fibrosis ◽  
Molecular Mechanisms ◽  
Epithelial Mesenchymal Transition ◽  
Organic Anion ◽  
Organic Anion Transporter ◽  
Indoxyl Sulfate ◽  
Uremic Toxin ◽  
Mesenchymal Transition ◽  
Anion Transporter

Activation of mTORC1 (mechanistic target of rapamycin complex 1) in renal tissue has been reported in chronic kidney disease (CKD)-induced renal fibrosis. However, the molecular mechanisms responsible for activating mTORC1 in CKD pathology are not well understood. The purpose of this study was to identify the uremic toxin involved in mTORC1-induced renal fibrosis. Among the seven protein-bound uremic toxins, only indoxyl sulfate (IS) caused significant activation of mTORC1 in human kidney 2 cells (HK-2 cells). This IS-induced mTORC1 activation was inhibited in the presence of an organic anion transporter inhibitor, a NADPH oxidase inhibitor, and an antioxidant. IS also induced epithelial–mesenchymal transition of tubular epithelial cells (HK-2 cells), differentiation of fibroblasts into myofibroblasts (NRK-49F cells), and inflammatory response of macrophages (THP-1 cells), which are associated with renal fibrosis, and these effects were inhibited in the presence of rapamycin (mTORC1 inhibitor). In in vivo experiments, IS overload was found to activate mTORC1 in the mouse kidney. The administration of AST-120 or rapamycin targeted to IS or mTORC1 ameliorated renal fibrosis in Adenine-induced CKD mice. The findings reported herein indicate that IS activates mTORC1, which then contributes to renal fibrosis. Therapeutic interventions targeting IS and mTORC1 could be effective against renal fibrosis in CKD.

Renal organic anion transporter 1 is maldistributed and diminishes in proximal tubule cells but increases in vasculature after ischemia and reperfusion

2008 ◽  
Vol 295 (6) ◽  
pp. F1807-F1816 ◽  
Author(s):  
Osun Kwon ◽  
Wei-Wei Wang ◽  
Shane Miller
Keyword(s):  
Proximal Tubule ◽  
Ischemia Reperfusion ◽  
Organic Anion ◽  
Basolateral Membrane ◽  
Kidney Injury ◽  
Organic Anion Transporter ◽  
Membrane Domain ◽  
Proximal Tubule Cells ◽  
Anion Transporter ◽  
Tubule Cells

Renal solute clearances are reduced in ischemic acute kidney injury. However, the mechanisms explaining how solute clearance is impaired have not been clarified. Recently, we reported that cadaveric renal allografts exhibit maldistribution of organic anion transporter 1 (OAT1) in proximal tubule cells after ischemia and reperfusion, resulting in impairment of PAH clearance. In the present study, we characterized renal OAT1 in detail after ischemia-reperfusion using a rat model. We analyzed renal OAT1 using confocal microscopy with a three-dimensional reconstruction of serial optical images, Western blot, and quantitative real-time RT-PCR. OAT1 was distributed to basolateral membranes of proximal tubule cells in controls. With ischemia, OAT1 decreased in basolateral membrane, especially in the lateral membrane domain, and appeared diffusely in cytoplasm. After reperfusion following 60-min ischemia, OAT1 often formed cytoplasmic aggregates. The staining for OAT1 started reappearing in lateral membrane domain 1 h after reperfusion. The basolateral membrane staining was relatively well discernable at 240 h of reperfusion. Of note, a distinct increase in OAT1 expression was noted in vasculature early after ischemia and after reperfusion. The total amount of OAT1 protein expression in the kidney diminished after ischemia-reperfusion in a duration-dependent manner until 72 h, when they began to recover. However, even at 240 h, the amount of OAT1 did not reach control levels. The kidney tissues tended to show a remarkable but transient increase in mRNA expression for OAT1 at 5 min of ischemia. Our findings may provide insights of renal OAT1 in its cellular localization and response during ischemic acute kidney injury and recovery from it.

scholarly journals Remote sensing and signaling in kidney proximal tubules stimulates gut microbiome-derived organic anion secretion

2019 ◽  
Vol 116 (32) ◽  
pp. 16105-16110 ◽  
Author(s):  
Jitske Jansen ◽  
Katja Jansen ◽  
Ellen Neven ◽  
Ruben Poesen ◽  
Amr Othman ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Gut Microbiome ◽  
Organic Anion ◽  
Organic Anion Transporter ◽  
Indoxyl Sulfate ◽  
Regulation Mechanism ◽  
Uremic Toxin ◽  
Proximal Tubule Cell ◽  
Anion Secretion ◽  
Anion Transporter

Membrane transporters and receptors are responsible for balancing nutrient and metabolite levels to aid body homeostasis. Here, we report that proximal tubule cells in kidneys sense elevated endogenous, gut microbiome-derived, metabolite levels through EGF receptors and downstream signaling to induce their secretion by up-regulating the organic anion transporter-1 (OAT1). Remote metabolite sensing and signaling was observed in kidneys from healthy volunteers and rats in vivo, leading to induced OAT1 expression and increased removal of indoxyl sulfate, a prototypical microbiome-derived metabolite and uremic toxin. Using 2D and 3D human proximal tubule cell models, we show that indoxyl sulfate induces OAT1 via AhR and EGFR signaling, controlled by miR-223. Concomitantly produced reactive oxygen species (ROS) control OAT1 activity and are balanced by the glutathione pathway, as confirmed by cellular metabolomic profiling. Collectively, we demonstrate remote metabolite sensing and signaling as an effective OAT1 regulation mechanism to maintain plasma metabolite levels by controlling their secretion.

scholarly journals IRIP, a New Ischemia/Reperfusion-Inducible Protein That Participates in the Regulation of Transporter Activity

2005 ◽  
Vol 25 (15) ◽  
pp. 6496-6508 ◽  
Author(s):  
Wei Jiang ◽  
Olga Prokopenko ◽  
Lawrence Wong ◽  
Masayori Inouye ◽  
Oleg Mirochnitchenko
Keyword(s):  
Ischemia Reperfusion ◽  
Organic Anion ◽  
Organic Anion Transporter ◽  
Monoamine Transporters ◽  
Interacting Protein ◽  
Anion Transporter ◽  
Endocrine Organs ◽  
Differential Display Analysis ◽  
Inducible Protein ◽  
Interfering Rna

ABSTRACT We report the identification and characterization of a new ischemia/reperfusion-inducible protein (IRIP), which belongs to the SUA5/YrdC/YciO protein family. IRIP cDNA was isolated in a differential display analysis of an ischemia/reperfusion-treated kidney RNA sample. Mouse IRIP mRNA was expressed in all tissues tested, the highest level being in the testis, secretory, and endocrine organs. Besides ischemia/reperfusion, endotoxemia also activated the expression of IRIP in the liver, lung, and spleen. The transporter regulator RS1 was identified as an IRIP-interacting protein in yeast two-hybrid screening. The interaction between IRIP and RS1 was further confirmed in coimmunoprecipitation assays. A possible role of IRIP in regulating transporter activity was subsequently investigated. IRIP overexpression inhibited endogenous 1-methyl-4-phenylpyridinium (MPP+) uptake activity in HeLa cells. The activities of exogenous organic cation transporters (OCT2 and OCT3), organic anion transporter (OAT1), and monoamine transporters were also inhibited by IRIP. Conversely, inhibition of IRIP expression by small interfering RNA or antisense RNA increased MPP+ uptake. We measured transport kinetics of OCT2-mediated uptake and demonstrated that IRIP overexpression significantly decreased V max but did not affect Km . On the basis of these results, we propose that IRIP regulates the activity of a variety of transporters under normal and pathological conditions.

scholarly journals Pharmacologic Targeting of BET Proteins Attenuates Hyperuricemic Nephropathy in Rats

2021 ◽  
Vol 12 ◽  
Author(s):  
Chongxiang Xiong ◽  
Jin Deng ◽  
Xin Wang ◽  
Xiaofei Shao ◽  
Qin Zhou ◽  
...  
Keyword(s):  
Uric Acid ◽  
Epithelial To Mesenchymal Transition ◽  
Organic Anion ◽  
Mesenchymal Cell ◽  
Serum Levels ◽  
Organic Anion Transporter ◽  
Vimentin Expression ◽  
Mesenchymal Transition ◽  
Expression Levels ◽  
Anion Transporter

Hyperuricemia is an independent risk factor for renal damage and promotes the progression of chronic kidney disease. In this study, we investigated the effect of I-BET151, a small-molecule inhibitor targeting the bromodomain and extraterminal (BET) proteins, on the development of hyperuricemic nephropathy (HN), and the mechanisms involved. Expression levels of bromodomain-containing protein 2 and 4, but not 3 were increased in the kidney of rats with HN; administration of I-BET151 effectively prevented renal dysfunction, decreased urine microalbumin, and attenuated renal fibrosis as indicated by reduced activation of renal interstitial fibroblasts and expression of fibronectin and collagen I in HN rats. Mechanistic studies show that I-BET151 treatment inhibited transition of renal epithelial cells to a mesenchymal cell type as evidenced by preservation of E-cadherin and reduction of vimentin expression. This was coincident with reduced expression of TGF-β1 and dephosphorylation of Smad3 and ERK1/2. I-BET151 was also effective in inhibiting phosphorylation of NF-κB, expression of multiple cytokines and chemokines, and infiltration of macrophages to the injured kidney. Although there were increased serum levels of uric acid and xanthine oxidase, an enzyme that catalyzes production of uric acid, and decreased expression of renal organic anion transporter 1 and 3 that promote urate excretion in the model of HN, and reduced expression levels of urine uric acid, I-BET151 treatment did not affect these responses. Collectively, our results indicate that I-BET151 alleviates HN by inhibiting epithelial to mesenchymal transition and inflammation in association with blockade of TGF-β, ERK1/2 and NF-κB signaling.

Probiotic Lactobacillus paracasei HII01 protects rats against obese-insulin resistance-induced kidney injury and impaired renal organic anion transporter 3 function

2018 ◽  
Vol 132 (14) ◽  
pp. 1545-1563 ◽  
Author(s):  
Keerati Wanchai ◽  
Sakawdaurn Yasom ◽  
Wannipa Tunapong ◽  
Titikorn Chunchai ◽  
Sathima Eaimworawuthikul ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Er Stress ◽  
Organic Anion ◽  
Lactobacillus Paracasei ◽  
Organic Anion Transporter ◽  
Renal Handling ◽  
Anion Transporter ◽  
Obese Rats ◽  
Organic Anion Transporter 3 ◽  
Lactobacillus Paracasei Hii01

The relationship between gut dysbiosis and obesity is currently acknowledged to be a health topic which causes low-grade systemic inflammation and insulin resistance and may damage the kidney. Organic anion transporter 3 (Oat3) has been shown as a transporter responsible for renal handling of gut microbiota products which are involved in the progression of metabolic disorder. The present study investigated the effect of probiotic supplementation on kidney function, renal Oat3 function, inflammation, endoplasmic reticulum (ER) stress, and apoptosis in obese, insulin-resistant rats. After 12 weeks of being provided with either a normal or a high-fat diet (HF), rats were divided into normal diet (ND); ND treated with probiotics (NDL); HF; and HF treated with probiotic (HFL). Lactobacillus paracasei HII01 1 × 108 colony forming unit (CFU)/ml was administered to the rats daily by oral gavage for 12 weeks. Obese rats showed significant increases in serum lipopolysaccharide (LPS), plasma lipid profiles, and insulin resistance. Renal Oat 3 function was decreased along with kidney dysfunction in HF-fed rats. Obese rats also demonstrated the increases in inflammation, ER stress, apoptosis, and gluconeogenesis in the kidneys. These alterations were improved by Lactobacillus paracasei HII01 treatment. In conclusion, probiotic supplementation alleviated kidney inflammation, ER stress, and apoptosis, leading to improved kidney function and renal Oat3 function in obese rats. These benefits involve the attenuation of hyperlipidemia, systemic inflammation, and insulin resistance. The present study also suggested the idea of remote sensing and signaling system between gut and kidney by which probiotic might facilitate renal handling of gut microbiota products through the improvement of Oat3 function.

scholarly journals Snai1-induced partial epithelial–mesenchymal transition orchestrates p53–p21-mediated G2/M arrest in the progression of renal fibrosis via NF-κB-mediated inflammation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ruochen Qi ◽  
Jiyan Wang ◽  
Yamei Jiang ◽  
Yue Qiu ◽  
Ming Xu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Cycle Arrest ◽  
Renal Fibrosis ◽  
Epithelial Mesenchymal Transition ◽  
Interstitial Fibrosis ◽  
Ischemia Reperfusion ◽  
Underlying Mechanism ◽  
Mesenchymal Transition ◽  
Cycle Arrest ◽  
Renal Fibrogenesis

AbstractRenal fibrosis is the common feature of all progressive kidney diseases and exerts great burden on public health worldwide. The maladaptive repair mechanism of tubular epithelial cells, an important mediator of renal fibrogenesis, manifests with partial epithelial–mesenchymal transition (EMT) and cell cycle arrest. The aim of this study is to investigate the possible correlation between partial EMT and cell cycle arrest, and elucidate the underlying mechanism. We examined human kidney allograft samples with interstitial fibrosis and three mice renal fibrosis models, unilateral ureter obstruction (UUO), ischemia–reperfusion injury, and Adriamycin nephropathy. The partial EMT process and p53–p21 axis were elevated in both human allograft with interstitial fibrosis, as well as three mice renal fibrosis models, and showed a time-dependent increase as fibrosis progressed in the UUO model. Snai1 controlled the partial EMT process, and led to parallel changes in renal fibrosis, G2/M arrest, and inflammation. p53–p21 axis arrested cell cycle at G2/M, and prompted partial EMT and fibrosis together with inflammation. NF-κB inhibitor Bay11-7082 disrupted the reciprocal loop between Snai1-induced partial EMT and p53–p21-mediated G2/M arrest. We demonstrated the reciprocal loop between partial EMT and G2/M arrest of TECs during renal fibrogenesis and revealed NF-κB-mediated inflammatory response as the underlying mechanism. This study suggests that targeting NF-κB might be a plausible therapeutic strategy to disrupt the reciprocal loop between partial EMT and G2/M arrest, therefore alleviating renal fibrosis.

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