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Angioplasty for cases of chronic total occlusion of renal artery with/without atrophic kidney is generally not recommended. We herein report a 57-year-old man who presented with renin-mediated refractory hypertension caused by occlusion of a unilateral renal artery leading to kidney atrophy (length: 69 mm). Angioplasty favorably achieved blood pressure control with normalized renin secretion and enlargement of the atrophic kidney to 85 mm. Timely angioplasty can be beneficial in select patients, even with an atrophic kidney and total occlusion, especially in cases with deterioration of hypertension within six months and the presence of collateral perfusion to the affected kidney.

Malignant hypertension, a form of hypertensive emergency, causes acute damage in vital organs such as the brain, eyes, and kidneys. We aimed to examine the concurrency of acute hypertensive damage across the target organs to elucidate the underlying analogous pathophysiology. This single-center retrospective study evaluated the characteristics of organ damage, short-term clinical course, and interorgan relationships in patients with malignant hypertension treated between 2008 and 2019. Baseline characteristics of 20 patients who met our inclusion criteria were mean age 48 ± 13 years and blood pressure 222 ± 18/142 ± 16 mmHg; the median estimated glomerular filtration rate and urinary protein level were 49 mL/min/1.73 m2 (interquartile range [IQR] 27–79) and 1.9 g/g creatinine (IQR 0.2–4.0), respectively. Posterior reversible encephalopathy syndrome (PRES) was found in 60% of patients with major involvement and a wide variety of distribution patterns in the brainstem. In the fundus, serous retinal detachment was found in 60% of patients. Patients with PRES and serous retinal detachment showed higher levels of urinary protein than those without symptoms (P = 0.007 and 0.02, respectively), and proteinuria >1 g/g creatinine highly complicated both PRES and serous retinal detachment (91%). Matrix analysis also showed that the three symptoms were highly associated with each other. These results demonstrate the close relationship and concurrency of hypertensive acute organ damage in the brain, eyes, and kidneys. A common analogous mechanism, such as hyperperfusion-induced capillary leakage in each organ, implies an underlying pathophysiology of PRES, serous retinal detachment, and proteinuria.

Orthotopic liver transplantation (OLT) is the only curative treatment for refractory chronic liver failure in liver cirrhosis. However, the supply of donated livers does not meet the demand for OLT due to donor organ shortage. Cell therapy using hepatocyte-like cells derived from human induced pluripotent stem cells (hiPSC-HLCs) is expected to mitigate the severity of liver failure, postpone OLT and ameliorate the insufficient liver supply. For the successful clinical translation of hiPSC-based cell therapy against liver cirrhosis, realistic animal models are required. In this study, we created a nonhuman primate (NHP) liver fibrosis model by repeated administrations of thioacetamide (TAA) and evaluated the short-term engraftment of hiPSC-HLCs in the fibrotic liver. The NHP liver fibrosis model reproduced well the pathophysiology of human liver cirrhosis including portal hypertension. Under immunosuppressive treatment, we transplanted ALBUMIN-GFP reporter hiPSC-HLC aggregates into the fibrotic livers of the NHP model via the portal vein. Fourteen days after the transplantation, GFP-expressing hiPSC-HLC clusters were detected in the portal areas of the fibrotic livers. These results will facilitate preclinical studies using the NHP liver fibrosis model and help establish iPSC-based cell therapies against liver cirrhosis.

We report a case in which diffusion-weighted magnetic resonance imaging (DWI) demonstrated renal artery stenosis-related renal ischemia and the therapeutic efficacy of revascularization. The patient was a 73-year-old man, who underwent descending thoracic aortic replacement due to DeBakey IIIb chronic aortic dissection, and who showed progressive renal dysfunction due to right renal artery stenosis caused by false lumen thrombosis. DWI demonstrated a decreased apparent diffusion coefficient (ADC) in the right kidney, indicating renal ischemia. Angioplasty with stenting restored renal perfusion and improved the renal function, resulting in the normalization of the decreased ADC in the treated kidney. Thus, DWI can be used to monitor renal ischemia in cases involving advanced renal artery stenosis.

Uremic toxins are suggested to be involved in the pathophysiology of hemodialysis (HD) patients. However, the profile of uremic solutes in HD patients has not been fully elucidated. In this study using capillary electrophoresis mass spectrometry (CE-MS), we comprehensively quantified the serum concentrations of 122 ionic solutes before and after HD in 11 patients. In addition, we compared the results with those in non-HD patients with chronic kidney disease (CKD) to identify HD patient-specific solutes. We identified 38 solutes whose concentrations were higher in pre-HD than in CKD stage G5. Ten solutes among them did not significantly accumulate in non-HD CKD patients, suggesting that these solutes accumulate specifically in HD patients. We also identified 23 solutes whose concentrations were lower in both pre- and post-HD than in CKD stage G5. The serum levels of 14 solutes among them were not affected by renal function in non-HD patients, suggesting that these solutes tend to be lost specifically in HD patients. Our data demonstrate that HD patients have a markedly different profile of serum uremic solute levels compared to that in non-HD CKD patients. The solutes identified in our study may contribute to the pathophysiology of HD patients.

18F-FDG PET/CT has been used as an indicator of chemotherapy effects, but cancer cells can remain even when no FDG uptake is detected, indicating the importance of exploring other metabolomic pathways. Therefore, we explored the amino acid metabolism, including L-type amino acid transporter-1 (LAT1), in breast cancer tissues and clarified the role of LAT1 in therapeutic resistance and clinical outcomes of patients. We evaluated LAT1 expression before and after neoadjuvant chemotherapy and examined the correlation of glucose uptake using FDG-PET with the pathological response of patients. It revealed that LAT1 levels correlated with proliferation after chemotherapy, and amino acid and glucose metabolism were closely correlated. In addition, LAT1 was considered to be involved in treatment resistance and sensitivity only in luminal type breast cancer. Results of in vitro analyses revealed that LAT1 promoted amino acid uptake, which contributed to energy production by supplying amino acids to the TCA cycle. However, in MCF-7 cells treated with chemotherapeutic agents, oncometabolites and branched-chain amino acids also played a pivotal role in energy production and drug resistance, despite decreased glucose metabolism. In conclusion, LAT1 was involved in drug resistance and could be a novel therapeutic target against chemotherapy resistance in luminal type breast cancer.

Sporadic inclusion body myositis (sIBM) is the most common idiopathic inflammatory myopathy, and several reports have suggested that mitochondrial abnormalities are involved in its etiology.We recruited 9 sIBM patients and found significant histological changes and an elevation of growth differential factor 15 (GDF15), a marker of mitochondrial disease, strongly suggesting the involvement of mitochondrial dysfunction. Bioenergetic analysis of sIBM patient myoblasts revealed impaired mitochondrial function.Decreased ATP production, reduced mitochondrial size and reduced mitochondrial dynamics were also observed in sIBM myoblasts. Cell vulnerability to oxidative stress also suggested the existence of mitochondrial dysfunction.Mitochonic acid-5 (MA-5) increased the cellular ATP level, reduced mitochondrial ROS, and provided protection against sIBM myoblast death.MA-5 also improved the survival of sIBM skin fibroblasts as well as mitochondrial morphology and dynamics in these cells. The reduction in the gene expression levels of Opa1 and Drp1 was also reversed by MA-5, suggesting the modification of the fusion/fission process. These data suggest that MA-5 may provide an alternative therapeutic strategy for treating not only mitochondrial diseases but also sIBM.

Unlike complete deficiency of hypoxanthine phosphoribosyltransferase (HPRT) (i.e., Lesch–Nyhan syndrome), partial HPRT deficiency causes HPRT-related hyperuricemia without neurological symptoms. Herein, we describe a 22-year-old man without neurological symptoms that presented gout, hyperuricemia (serum urate level, 12.2 mg/dL), multiple renal microcalculi, and a family history of juvenile gout that was exhibited by his brother and grandfather. Genetic testing revealed a novel missense mutation, c.103G>A (p.V35M), in the HPRT1 gene, and biochemical testing (conducted using the patient’s erythrocytes) showed that the patient retained only 12.4% HPRT enzymatic activity compared to that exhibited by a healthy control subject. We thus diagnosed the patient with HPRT-related hyperuricemia caused by partial HPRT deficiency. After his serum urate level was controlled via treatment with febuxostat, his gout did not recur. Thus, this study emphasizes that HPRT deficiency should be considered as a potential cause of familial juvenile gout, even in the absence of neurological symptoms. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13730-020-00459-9) contains supplementary material, which is available to authorized users.

Human induced pluripotent stem cells (hiPSCs) are expected to be both a revolutionary cell source for regenerative medicine and a powerful tool to investigate the molecular mechanisms underlying human cell development in vitro. In the present study, we tried to elucidate the steroidogenic differentiation processes using hiPSC-derived intermediate mesoderm (IM) that is known to be the origin of the human adrenal cortex and gonads. We first performed chemical screening to identify small molecules that induce steroidogenic differentiation of IM cells expressing Odd-skipped related 1 (OSR1), an early IM marker. We identified cabergoline as an inducer of 3β-hydroxysteroid dehydrogenase, an essential enzyme for adrenogonadal steroidogenesis. Although cabergoline is a potent dopamine D2 receptor agonist, additional experiments showed that cabergoline exerted effects as a low-affinity agonist of D1 receptors by increasing intracellular cyclic AMP. Further analysis of OSR1+ cells transfected with steroidogenic factor-1/adrenal 4 binding protein revealed that D1 receptor agonist upregulated expression of various steroidogenic enzymes and increased secretion of steroid hormones synergistically with adrenocorticotropic hormone. These results suggest the importance of dopamine D1 receptor signalling in steroidogenic differentiation, which contributes to effective induction of steroidogenic cells from hiPSCs.

BACKGROUND: Ferroptosis, nonapoptotic cell death mediated by free radical reactions and driven by the oxidative degradation of lipids, is a therapeutic target because of its role in organ damage, including AKI. Ferroptosis-causing radicals that are targeted by ferroptosis suppressors have not been unequivocally identified. Because certain cytochrome P450 substrate drugs can prevent lipid peroxidation via obscure mechanisms, we evaluated their antiferroptotic potential and used them to identify ferroptosis-causing radicals. METHODS: Using a cell-based assay, we screened cytochrome P450 substrate compounds to identify drugs with antiferroptotic activity and investigated the underlying mechanism. To evaluate radical-scavenging activity, we used electron paramagnetic resonance-spin trapping methods and a fluorescence probe for lipid radicals, NBD-Pen, that we had developed. We then assessed the therapeutic potency of these drugs in mouse models of cisplatin-induced AKI and LPS/galactosamine-induced liver injury. RESULTS: We identified various US Food and Drug Administration-approved drugs and hormones that have antiferroptotic properties, including rifampicin, promethazine, omeprazole, indole-3-carbinol, carvedilol, propranolol, estradiol, and thyroid hormones. The antiferroptotic drug effects were closely associated with the scavenging of lipid peroxyl radicals but not significantly related to interactions with other radicals. The elevated lipid peroxyl radical levels were associated with ferroptosis onset, and known ferroptosis suppressors, such as ferrostatin-1, also functioned as lipid peroxyl radical scavengers. The drugs exerted antiferroptotic activities in various cell types, including tubules, podocytes, and renal fibroblasts. Moreover, in mice, the drugs ameliorated AKI and liver injury, with suppression of tissue lipid peroxidation and decreased cell death. CONCLUSIONS: Although elevated lipid peroxyl radical levels can trigger ferroptosis onset, some drugs that scavenge lipid peroxyl radicals can help control ferroptosis-related disorders, including AKI.

Although susceptibility to cardiovascular disease (CVD) is different for every patient, why some patients with type 2 diabetes mellitus (T2DM) develop CVD while others are protected has not yet been clarified. Using T2DM-patient-derived human induced pluripotent stem cells (hiPSCs), we found that in patients protected from CVD, there was significantly elevated expression of an esterase, arylacetamide deacetylase (AADAC), in vascular smooth muscle cells (VSMCs). We overexpressed this esterase in human primary VSMCs and VSMCs differentiated from hiPSCs and observed that the number of lipid droplets was significantly diminished. Further metabolomic analyses revealed a marked reduction in storage lipids and an increase in membrane phospholipids, suggesting changes in the Kennedy pathway of lipid bioassembly. Cell migration and proliferation were also significantly decreased in AADAC-overexpressing VSMCs. Moreover, apolipoprotein E (Apoe)-knockout mice overexpressing VSMC-specific Aadac showed amelioration of atherosclerotic lesions. Our findings suggest that higher AADAC expression in VSMCs protects T2DM patients from CVD.

Diabetic kidney disease is a major cause of renal failure that urgently necessitates a breakthrough in disease management. Here we show using untargeted metabolomics that levels of phenyl sulfate, a gut microbiota-derived metabolite, increase with the progression of diabetes in rats overexpressing human uremic toxin transporter SLCO4C1 in the kidney, and are decreased in rats with limited proteinuria. In experimental models of diabetes, phenyl sulfate administration induces albuminuria and podocyte damage. In a diabetic patient cohort, phenyl sulfate levels significantly correlate with basal and predicted 2-year progression of albuminuria in patients with microalbuminuria. Inhibition of tyrosine phenol-lyase, a bacterial enzyme responsible for the synthesis of phenol from dietary tyrosine before it is metabolized into phenyl sulfate in the liver, reduces albuminuria in diabetic mice. Together, our results suggest that phenyl sulfate contributes to albuminuria and could be used as a disease marker and future therapeutic target in diabetic kidney disease., Diabetes is a major cause of kidney disease. Here Kikuchi et al. show that phenol sulfate, a gut microbiota-derived metabolite, is increased in diabetic kidney disease and contributes to the pathology by promoting kidney injury, suggesting phenyl sulfate could be used a marker and therapeutic target for the treatment of diabetic kidney disease.

Although human genetic studies have implicated many susceptible genes associated with plasma lipid levels, their physiological and molecular functions are not fully characterized. Here we demonstrate that orphan G protein-coupled receptor 146 (GPR146) promotes activity of hepatic sterol regulatory element binding protein 2 (SREBP2) through activation of the extracellular signal-regulated kinase (ERK) signaling pathway, thereby regulating hepatic very low-density lipoprotein (VLDL) secretion, and subsequently circulating low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG) levels. Remarkably, GPR146 deficiency reduces plasma cholesterol levels substantially in both wild-type and LDL receptor (LDLR)-deficient mice. Finally, aortic atherosclerotic lesions are reduced by 90% and 70%, respectively, in male and female LDLR-deficient mice upon GPR146 depletion. Taken together, these findings outline a regulatory role for the GPR146/ERK axis in systemic cholesterol metabolism and suggest that GPR146 inhibition could be an effective strategy to reduce plasma cholesterol levels and atherosclerosis.

Background: Sporadic inclusion body myositis (sIBM) is the most common idiopathic inflammatory myopathy, and mitochondrial abnormalities may be involved. Methods: We recruited 9 sIBM patients and we examined mitochondrial functions with bioenergetic and examinations and dynamics of patient myoblasts with measuring a mitochondrial disease marker growth differential factor 15 (GDF15). We also examined the effect of a new candidate drug, Mitochondria acid-5 (MA-5). Findings: Bioenergetic analysis of sIBM patient myoblasts revealed damaged mitochondrial function with decreased ATP, mitochondrial size and impaired mitochondrial dynamics and cell vulnerability. MA-5 increased the ATP level and reduced mitochondrial ROS, following the protection against cell death. The reduced levels of Opa1 and Drp1 showed the impairment of mitochondrial fusion/fission process and that MA-5 ameliorated. Skin fibroblasts from sIBM patients can be used for diagnosis. Interpretation: GDF15 and MA-5 could provide both a new maker and therapeutic strategy for sIBM patients. Funding Statement: These works were supported in part by National grant-in-aid for scientific research from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (18H02822), Translational Research Network Program (C50) from Japan Agency for Medical Research and Development (AMED). MEXT and AMED, JAPAN. Declaration of Interests: The authors state: "None." Ethics Approval Statement: Myoblasts and fibroblasts obtained by muscle and skin biopsy of sIBM patients were collected in Tohoku University Hospital under the approval of the Ethical Committee of Tohoku University.

Sporadic inclusion body myositis (sIBM) is the most common idiopathic inflammatory myopathy, and several reports have suggested that mitochondrial abnormalities are involved in its etiology. We recruited 9 sIBM patients and found significant histological changes and an elevation of growth differential factor 15 (GDF15), a marker of mitochondrial disease, strongly suggesting the involvement of mitochondrial dysfunction. Bioenergetic analysis of sIBM patient myoblasts revealed impaired mitochondrial function. Decreased ATP production, reduced mitochondrial size and reduced mitochondrial dynamics were also observed in sIBM myoblasts. Cell vulnerability to oxidative stress also suggested the existence of mitochondrial dysfunction. Mitochonic acid-5 (MA-5) increased the cellular ATP level, reduced mitochondrial ROS, and provided protection against sIBM myoblast death. MA-5 also improved the survival of sIBM skin fibroblasts as well as mitochondrial morphology and dynamics in these cells. The reduction in the gene expression levels of Opa1 and Drp1 was also reversed by MA-5, suggesting the modification of the fusion/fission process. These data suggest that MA-5 may provide an alternative therapeutic strategy for treating not only mitochondrial diseases but also sIBM.

Acute kidney injury (AKI) is defined as a rapid loss of renal function resulting from various etiologies, with a mortality rate exceeding 60% among intensive care patients. Because conventional treatments have failed to alleviate this condition, the development of regenerative therapies using human induced pluripotent stem cells (hiPSCs) presents a promising new therapeutic option for AKI. We describe our methodology for generating renal progenitors from hiPSCs that show potential in ameliorating AKI. We established a multistep differentiation protocol for inducing hiPSCs into OSR1+SIX2+ renal progenitors capable of reconstituting three-dimensional proximal renal tubule-like structures in vitro and in vivo. Moreover, we found that renal subcapsular transplantation of hiPSC-derived renal progenitors ameliorated the AKI in mice induced by ischemia/reperfusion injury, significantly suppressing the elevation of blood urea nitrogen and serum creatinine levels and attenuating histopathological changes, such as tubular necrosis, tubule dilatation with casts, and interstitial fibrosis. To our knowledge, few reports demonstrating the therapeutic efficacy of cell therapy with renal lineage cells generated from hiPSCs have been published. Our results suggest that regenerative medicine strategies for kidney diseases could be developed using hiPSC-derived renal cells., ヒトiPS細胞由来の腎前駆細胞を使った細胞移植で急性腎障害(急性腎不全)のマウスに効果. 京都大学プレスリリース. 2016-07-22.

Mitochondria are key organelles implicated in a variety of processes related to energy and free radical generation, the regulation of apoptosis, and various signaling pathways. Mitochondrial dysfunction increases cellular oxidative stress and depletes ATP in a variety of inherited mitochondrial diseases and also in many other metabolic and neurodegenerative diseases. Mitochondrial diseases are characterized by the dysfunction of the mitochondrial respiratory chain, caused by mutations in the genes encoded by either nuclear DNA or mitochondrial DNA. We have hypothesized that chemicals that increase the cellular ATP levels may ameliorate the mitochondrial dysfunction seen in mitochondrial diseases. To search for the potential drugs for mitochondrial diseases, we screened an in-house chemical library of indole-3-acetic-acid analogs by measuring the cellular ATP levels in Hep3B human hepatocellular carcinoma cells. We have thus identified mitochonic acid 5 (MA-5), 4-(2,4-difluorophenyl)-2-(1H-indol-3-yl)-4-oxobutanoic acid, as a potential drug for enhancing ATP production. MA-5 is a newly synthesized derivative of the plant hormone, indole-3-acetic acid. Importantly, MA-5 improved the survival of fibroblasts established from patients with mitochondrial diseases under the stress-induced condition, including Leigh syndrome, MELAS (myopathy encephalopathy lactic acidosis and stroke-like episodes), Leber's hereditary optic neuropathy, and Kearns-Sayre syndrome. The improved survival was associated with the increased cellular ATP levels. Moreover, MA-5 increased the survival of mitochondrial disease fibroblasts even under the inhibition of the oxidative phosphorylation or the electron transport chain. These data suggest that MA-5 could be a therapeutic drug for mitochondrial diseases that exerts its effect in a manner different from anti-oxidant therapy.

The production of erythropoietin (EPO) by the kidneys, a principal hormone for the hematopoietic system, is reduced in patients with chronic kidney disease (CKD), eventually resulting in severe anemia. Although recombinant human EPO treatment improves anemia in patients with CKD, returning to full red blood cell production without fluctuations does not always occur. We established a method to generate EPO-producing cells from human induced pluripotent stem cells (hiPSCs) by modifying previously reported hepatic differentiation protocols. These cells showed increased EPO expression and secretion in response to low oxygen conditions, prolyl hydroxylase domain-containing enzyme inhibitors, and insulin-like growth factor 1. The EPO protein secreted from hiPSC-derived EPO-producing (hiPSC-EPO) cells induced the erythropoietic differentiation of human umbilical cord blood progenitor cells in vitro. Furthermore, transplantation of hiPSC-EPO cells into mice with CKD induced by adenine treatment improved renal anemia. Thus, hiPSC-EPO cells may be a useful tool for clarifying the mechanisms of EPO production and may be useful as a therapeutic strategy for treating renal anemia.

Tissue damage by oxidative stress is a key pathogenic mechanism in various diseases, including AKI and CKD. Thus, early detection of oxidative tissue damage is important. Using a tRNA-specific modified nucleoside 1-methyladenosine (m1A) antibody, we show that oxidative stress induces a direct conformational change in tRNA structure that promotes subsequent tRNA fragmentation and occurs much earlier than DNA damage. In various models of tissue damage (ischemic reperfusion, toxic injury, and irradiation), the levels of circulating tRNA derivatives increased rapidly. In humans, the levels of circulating tRNA derivatives also increased under conditions of acute renal ischemia, even before levels of other known tissue damage markers increased. Notably, the level of circulating free m1A correlated with mortality in the general population (n=1033) over a mean follow-up of 6.7 years. Compared with healthy controls, patients with CKD had higher levels of circulating free m1A, which were reduced by treatment with pitavastatin (2 mg/d; n=29). Therefore, tRNA damage reflects early oxidative stress damage, and detection of tRNA damage may be a useful tool for identifying organ damage and forming a clinical prognosis.

The oral adsorbent AST-120 is composed of spherical carbon particles and has an adsorption ability for certain small-molecular-weight compounds that accumulate in patients with chronic kidney disease (CKD). So far, very few compounds are known to be adsorbed by AST-120 in vivo. To examine the effect of AST-120 in vivo, we comprehensively evaluated the plasma concentrations of 146 compounds (61 anions and 85 cations) in CKD model rats, with or without four weeks of treatment with AST-120. By capillary electrophoresis with mass spectrometry, we identified 6 anions and 17 cations that were significantly decreased by AST-120 treatment. In contrast, we also identified 2 cations that were significantly increased by AST-120. Among them, 4 anions, apart from indoxyl sulfate and hippurate, and 19 cations were newly identified in this study. The plasma levels of N-acetyl-neuraminate, 4-pyridoxate, 4-oxopentanoate, glycine, γ-guanidinobutyrate, N-γ-ethylglutamine, allantoin, cytosine, 5-methylcytosine and imidazole-4-acetate were significantly increased in the CKD model compared with the sham-operated group, and were significantly decreased by AST-120 treatment. Therefore, these 10 compounds could be added as uremic compounds that indicate the effect of AST-120 treatment. This study provides useful information not only for identifying the indicators of AST-120, but also for clarifying changes in the metabolic profile by AST-120 treatment in the clinical setting.

Acute kidney injury (AKI) is a renal disease that is associated with high mortality. Current treatments mostly rely on supportive therapies and do not directly target the disease. Regenerative medicine, however, offers potentially direct AKI therapy through two strategies: cell transplantation and kidney reconstruction. Regarding cell transplantation, several cell types are potential sources, including hematopoietic stem cells, mesenchymal stem cells, and renal stem/progenitor cells within the adult kidney tissue or derived from human-induced pluripotent stem cells (iPSCs). On the other hand, kidney reconstruction could provide a curative treatment for severe AKI and consequent chronic kidney disease (CKD). Many methods have been proposed for the kidney reconstruction, including self-organization, blastocyst complementation, decellularization, and bioartificial kidneys. However, there are still a number of obstacles to overcome before reconstructed kidneys reach clinical use. In this review, we summarize the recent progresses in cell transplantation and kidney reconstruction as strategies to treating AKI.

A highly acidic environment surrounds proximal tubular cells as a result of their reabsorption of HCO(3)(-). It is unclear whether this luminal acidity affects proteinuria-induced progression of tubular cell damage. Here, we investigated the contribution of luminal acidity to superoxide (O(2)(·-)) production induced by oleic acid-bound albumin (OA-Alb) in proximal tubular cells. Acidic media significantly enhanced OA-Alb-induced O(2)(·-) production in the HK-2 proximal tubular cell line. Simultaneous treatment with both OA-Alb and acidic media led to phosphorylation of the intracellular pH sensor Pyk2. Highly phosphorylated Pyk2 associated with activation of Rac1, an essential subcomponent of NAD(P)H oxidase. Furthermore, knockdown of Pyk2 with siRNA attenuated the O(2)(·-) production induced by cotreatment with OA-Alb and acid. To assess whether luminal alkalinization abrogates proteinuria-induced tubular damage, we studied a mouse model of protein-overload nephropathy. NaHCO(3) feeding selectively alkalinized the urine and dramatically attenuated the accumulation of O(2)(·-)-induced DNA damage and proximal tubular injury. Overall, these observations suggest that luminal acidity aggravates proteinuria-induced tubular damage and that modulation of this acidic environment may hold potential as a therapeutic target for proteinuric kidney disease.

Background Patients who have been on continuous ambulatory peritoneal dialysis (CAPD) for over 10 years are known to have a risk of developing encapsulating peritoneal sclerosis (EPS). However, the prognosis of patients on CAPD for over 10 years remains unclear. Methods To better understand the efficacy of a variety of treatments for EPS, we retrospectively reviewed 25 patients who started CAPD at Toranomon Hospital from 1981 to 1997 and continued it for longer than 10 years. Results The CAPD catheter was removed without peritoneal lavage in the initial 3 patients and they developed massive ascites. They all died of infection without resolution of the ascites. Accordingly, in the remaining 13 patients who did not undergo kidney transplantation, peritoneal lavage therapy was performed for 12 months before removing the CAPD catheter. As a result, 4 patients did not develop EPS. However, 9 patients had EPS with ascites, among whom 4 died of EPS-related diseases and 5 are alive. Five patients underwent cadaveric donor kidney transplantation. At the time of surgery, the CAPD catheter was removed without peritoneal lavage; 1 patient suffered from massive ascites immediately, although this subsided within 3 months after kidney transplantation, and 4 patients remain free from EPS-related symptoms and are doing well. Conclusion Kidney transplantation may be an option for preventing EPS. This study showed that improvement of the uremic state as well as treatment with immunosuppressants including corticosteroids may contribute to preventing EPS.

Early detection and accurate monitoring of patients with chronic kidney disease (CKD) is likely to improve care and decrease the risk of cardiovascular and cerebrovascular diseases. As a new diagnostic tool, we examined the retention of uremic solutes as a simpler, more accurate method to assess renal function. To achieve this, we comprehensively evaluated these solutes in CKD patients. By capillary electrophoresis with mass spectrometry, we found 22 cations and 30 anions that accumulated significantly as the estimated glomerular filtration rate (eGFR) decreased. These compounds included 9 cations and 27 anions that were newly identified in this study. In contrast, we also found 7 cations (2 new) and 5 anions (all new) that decrease significantly as eGFR declines. We evaluated each substance for its suitability to detect early CKD stage. Compounds that are highly correlated with eGFR and whose plasma concentration changed in a manner approximated by the first-degree equation are excellent candidates for detecting CKD and identifying uremic toxins that might aggravate kidney function in the early stage of CKD. These results identify a number of uremic compounds, many of which are novel and which predict worsening renal function. These compounds provide diagnostic information and may be targets for therapies designed to treat the complications of CKD patients.

Summary: Human organic anion transporter OATP4C1 is a member of the OATP family predominantly expressed in the kidney, and contributes to the renal secretion of digoxin. However, little is known about the characteristics of OATP4C1-madiated transport. We examined the transport of estrone 3-sulfate, which is known as a substrate for other OATPs, by OATP4C1-expressing cells. Estrone 3-sulfate was efficiently transported by OATP4C1. The Michaelis-Menten constant for estrone 3-sulfate uptake by OATP4C1 was 26.6 ± 4.9 μ M. Transport of estrone 3-sulfate was significantly inhibited by triiodothyronine, chenodeoxycholic acid, bromosulfophtalein, and cyclosporine, whereas known substrates of OATP4C1, digoxin and ouabain, did not change OATP4C1-mediated transport. We further examined the mutual inhibition study between estrone 3-sulfate and digoxin. Digoxin partially inhibited the estrone 3-sulfate transport, and estrone 3-sulfate did not significantly inhibit digoxin transport. The estimated IC 50 value of digoxin for OATP4C1-mediated estrone 3-sulfate transport was 119 μ M. This value is not comparable with the Michaelis-Menten constant for digoxin uptake by OATP4C1 (7.8 μ M) reported by Mikkaichi et al. 1) In conclusion, we found that estrone 3-sulfate is a novel substrate for OATP4C1. Moreover, our results indicate that estrone 3-sulfate does not bind to the recognition site for digoxin in OATP4C1.

The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor pravastatin has been reported to have a beneficial effect on reducing the new onset of diabetes as well as lowering plasma lipids. Because pravastatin is a water-soluble organic anion, it cannot easily penetrate the lipid bilayer of the cell membrane. As the precise mechanisms of the effect of pravastatin on glucose metabolism and diabetes have not been clarified, we examined the roles of the organic anion transporter family on pravastatin-treated islet and adipocyte functions. Rat oatp1/slco1a1, oatp2/slco1a4 and oatp3/slco1a5 were expressed in the pancreas, and rat oatp3/slco1a5 was also detected in rat insulinoma cell line INS-1e. Pravastatin was transported not only by oatp1/slco1a1 and oatp2/slco1a4, but also by rat oatp3/slco1a5. Pravastatin uptake into INS-1e cells was detected and this transport was inhibited by sulfobromophthalein and rifampicin, both of which are known to inhibit oatp family-mediated uptake. In addition, pravastatin enhanced the glucose-stimulated insulin secretion from INS-1e cells. When fat-loaded db/db mice were treated with pravastatin, glucose intolerance and insulin resistance were prevented. In addition, insulin secretion from isolated islets was enhanced by pravastatin. These data suggest that pravastatin has pleiotropic effects on islets through membrane transport under high fat/glucose conditions.

The purpose of the present study was to determine the absolute protein expression levels of various transporters in renal brush-border membrane (BBM) and basolateral membrane (BLM) fractions, in order to understand the quantitative differences in average transport activities among different transporters at each cellular membrane. BBM and BLM fractions of rat kidney were prepared and digested with trypsin, and simultaneous absolute quantification of 28 transporters and a BLM marker, Na(+)/K(+)-ATPase, was performed using our established quantitative-targeted absolute proteomics (QTAP) technique. In BBM fraction, the protein expression levels of bcrp, urat1, mate1, octl1, mrp4, mdr1a, and abca3 were 40.3, 22.2, 8.90, 4.85, 4.69, 3.22, and 0.976 fmol/μg protein, respectively. In BLM fraction, the protein expression levels of oat1, oat3, oct1, mrp6, and mrp1 were 10.6, 10.2, 4.59, 0.724, and 0.271 fmol/μg protein, respectively. The expression levels of abca2, abca4, abca5, abca12, abcb4, mrp5, abcc9, abcg1, abcg5, lat1, ntcp, pgt, oatp2b1, oatp1b2, oatp3a1, and oct3 were under the limit of quantification in both fractions. The quantitative transporter protein expression profiles at these membranes, as determined by QTAP analysis, should be helpful to understand the contributions of individual transporters to renal excretion of xenobiotics and endogenous compounds.

Mitochondrial dysfunction causes increased oxidative stress and depletion of ATP, which are involved in the etiology of a variety of renal diseases, such as CKD, AKI, and steroid–resistant nephrotic syndrome. Antioxidant therapies are being investigated, but clinical outcomes have yet to be determined. Recently, we reported that a newly synthesized indole derivative, mitochonic acid 5 (MA-5), increases cellular ATP level and survival of fibroblasts from patients with mitochondrial disease. MA-5 modulates mitochondrial ATP synthesis independently of oxidative phosphorylation and the electron transport chain. Here, we further investigated the mechanism of action for MA-5. Administration of MA-5 to an ischemia-reperfusion injury model and a cisplatin–induced nephropathy model improved renal function. In in vitro bioenergetic studies, MA-5 facilitated ATP production and reduced the level of mitochondrial reactive oxygen species (ROS) without affecting activity of mitochondrial complexes I–IV. Additional assays revealed that MA-5 targets the mitochondrial protein mitofilin at the crista junction of the inner membrane. In Hep3B cells, overexpression of mitofilin increased the basal ATP level, and treatment with MA-5 amplified this effect. In a unique mitochondrial disease model (Mitomice with mitochondrial DNA deletion that mimics typical human mitochondrial disease phenotype), MA-5 improved the reduced cardiac and renal mitochondrial respiration and seemed to prolong survival, although statistical analysis of survival times could not be conducted. These results suggest that MA-5 functions in a manner differing from that of antioxidant therapy and could be a novel therapeutic drug for the treatment of cardiac and renal diseases associated with mitochondrial dysfunction.

SummaryTransplantation of in-vitro-generated organ buds is a promising approach toward regenerating functional and vascularized organs. Though it has been recently shown in the context of liver models, demonstrating the applicability of this approach to other systems by delineating the molecular mechanisms guiding organ bud formation is critical. Here, we demonstrate a generalized method for organ bud formation from diverse tissues by combining pluripotent stem cell-derived tissue-specific progenitors or relevant tissue samples with endothelial cells and mesenchymal stem cells (MSCs). The MSCs initiated condensation within these heterotypic cell mixtures, which was dependent upon substrate matrix stiffness. Defining optimal mechanical properties promoted formation of 3D, transplantable organ buds from tissues including kidney, pancreas, intestine, heart, lung, and brain. Transplanted pancreatic and renal buds were rapidly vascularized and self-organized into functional, tissue-specific structures. These findings provide a general platform for harnessing mechanical properties to generate vascularized, complex organ buds with broad applications for regenerative medicine.

Item does not contain fulltext Chronic kidney disease (CKD) is a condition that affects approximately 10% of the adult population in developed countries. In patients with CKD adequate renal clearance is compromised, resulting in the accumulation of a plethora of uremic solutes. These uremic retention solutes, also known as uremic toxins, are a heterogeneous group of organic compounds, many are too large to be filtered (middle molecules) or are protein-bound. Tubular secretion shifts the binding and allows for active secretion of such solutes. To mediate urinary solute excretion, renal proximal tubules are equipped with a range of transporters that cooperate in basolateral uptake and luminal excretion. These putative uremic toxins are poorly filtered across dialysis membranes because they are protein bound and current dialysis therapy does not correct the full spectrum of uremic toxicity. Residual renal function, which may represent an important contribution of solutes secreted by the proximal tubule rather than unreabsorbed filtrate, is an important predictor of survival of CKD patients. Many of the transporters that mediate the renal excretion of uremic retention solutes were first recognized as mediators of drug trafficking and drug-drug interactions, and a considerable amount of literature concerning the actions of these transporters antedates the recognition of their importance in the proximal renal tubular transport of uremic retention solutes. These transporters include members belonging to the organic cation/anion/zwitterion solute carrier family, such as the organic anion transporters (OAT)1, OAT3, and OATP4C1, and to the adenosine triphosphate binding cassette superfamily of transmembrane transporters, including the multidrug resistance proteins and breast cancer resistance protein. This article draws on this body of information to describe the renal tubular clearance mechanisms for uremic toxins, as well as the intracellular events associated with their accumulation, involving activation of the aryl hydrocarbon receptor, disturbance of mitochondrial functioning, and competition with metabolizing enzymes.

The accumulated uremic toxins inhibit the expression of various renal transporters and this inhibition may further reduce renal function and subsequently cause the accumulation of uremic toxins. However, the precise mechanism of the nephrotoxicity of uremic toxins on renal transport has been poorly understood. Here we report that indoxyl sulfate, one of the potent uremic toxins, directly suppresses the renal-specific organic anion transporter SLCO4C1 expression through a transcription factor GATA3. The promoter region of SLCO4C1 gene has several GATA motifs, and indoxyl sulfate up-regulated GATA3 mRNA and subsequently down-regulated SLCO4C1 mRNA. Overexpression of GATA3 significantly reduced SLCO4C1 expression, and silencing of GATA3 increased SLCO4C1 expression vice versa. Administration of indoxyl sulfate in rats reduced renal expression of slco4c1 and under this condition, plasma level of guanidinosuccinate, one of the preferable substrates of slco4c1, was significantly increased without changing plasma creatinine. Furthermore, in 5/6 nephrectomized rats, treatment with oral adsorbent AST-120 significantly decreased plasma indoxyl sulfate level and conversely increased the expression of slco4c1, following the reduction of plasma level of guanidinosuccinate. These data suggest that the removal of indoxyl sulfate and blocking its signal pathway may help to restore the SLCO4C1-mediated renal excretion of uremic toxins in CKD.

Kidneys are enlarged by aberrant proliferation of tubule epithelial cells leading to the formation of numerous cysts, nephron loss, and interstitial fibrosis in polycystic kidney disease (PKD). Pioglitazone (PIO), a PPAR-γagonist, decreased cell proliferation, interstitial fibrosis, and inflammation, and ameliorated PKD progression in PCK rats (Am. J. Physiol.-Renal, 2011). To explore genetic mechanisms involved, changes in global gene expression were analyzed. By Gene Set Enrichment Analysis of 30655 genes, 13 of the top 20 downregulated gene ontology biological process gene sets and six of the top 20 curated gene set canonical pathways identified to be downregulated by PIOtreatment were related to cell cycle and proliferation, including EGF, PDGF and JNK pathways. Their relevant pathways were identified using the Kyoto Encyclopedia of Gene and Genomes database. Stearoyl-coenzyme A desaturase 1 is a key enzyme in fatty acid metabolism found in the top 5 genes downregulated by PIO treatment. Immunohistochemical analysis revealed that the gene product of this enzyme was highly expressed in PCK kidneys and decreased by PIO. These data show that PIO alters the expression of genes involved in cell cycle progression, cell proliferation, and fatty acid metabolism.

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited systemic disease characterized by renal cyst expansion, resulting in renal failure. With the progression of renal damage, the accumulation of uremic compounds is recently reported to subsequently cause further renal damage and hypertension. Finding uremic toxins and sensitive markers for detecting the early stage of ADPKD is necessary to clarify its pathophysiological process and to prevent its progression. The aim of this study was to analyze the profile of uremic retention solutes of ADPKD by capillary electrophoresis-mass spectrometry (CE-MS) using the Han:SPRD rat model.Two hundred and ninety-seven cations and 190 anions were comprehensively analyzed by CE-MS in Han:SPRD rats and control rats.We found 21 cations and 19 anions that accumulated significantly in the heterozygous (Cy/+) ADPKD rat model compared with control rats. Among the compounds, increases in 5-methyl-2'-deoxycytidine, glucosamine, ectoine, allantoate, α-hydroxybenzoate, phenaceturate and 3-phenylpropionate and decreases in 2-deoxycytidine, decanoate and 10-hydroxydecanoate were newly identified in the ADPKD Cy/+ rats.We identified uremic retention solutes in ADPKD Cy/+ rats. Compounds related to ADPKD could be useful markers for detecting the early stage of ADPKD.

Hypertension in patients with chronic kidney disease (CKD) strongly associates with cardiovascular events. Among patients with CKD, reducing the accumulation of uremic toxins may protect against the development of hypertension and progression of renal damage, but there are no established therapies to accomplish this. Here, overexpression of human kidney-specific organic anion transporter SLCO4C1 in rat kidney reduced hypertension, cardiomegaly, and inflammation in the setting of renal failure. In addition, SLCO4C1 overexpression decreased plasma levels of the uremic toxins guanidino succinate, asymmetric dimethylarginine, and the newly identified trans-aconitate. We found that xenobiotic responsive element core motifs regulate SLCO4C1 transcription, and various statins, which act as inducers of nuclear aryl hydrocarbon receptors, upregulate SLCO4C1 transcription. Pravastatin, which is cardioprotective, increased the clearance of asymmetric dimethylarginine and trans-aconitate in renal failure. These data suggest that drugs that upregulate SLCO4C1 may have therapeutic potential for patients with CKD.

Two bacterial strains isolated from different hospitals in Japan were subjected to a polyphasic analysis. Strains IFM 0803T and IFM 10383 were found to have morphological, biochemical, physiological and chemotaxonomic properties consistent with their classification in the genus Nocardia. Strains IFM 0803T and IFM 10383 clustered with the type strain of Nocardia xishanensis, showing 16S rRNA gene sequence similarities of 98.6–98.9 % with this species. The novel strains could be distinguished from N. xishanensis by a range of phenotypic properties. Based on their phenotypic and phylogenetic characteristics, the two isolates are proposed as members of a novel species of the genus Nocardia, Nocardia exalbida sp. nov., with the type strain IFM 0803T (=NBRC 100660T=JCM 12667T=DSM 44883T).

Successful Peritoneal Dialysis After Renal Transcatheter Arterial Embolization in Autosomal Dominant Polycystic Kidney Disease To the Editor: When continuous ambulatory peritoneal dialysis (CAPD) is performed in patients with autosomal dominant polycystic kidney disease (ADPKD), various complications specific to ADPKD, such as abdominal hernias, leakage of dialysate from the peritoneal cavity, and enlargement of the kidneys or liver, need to be considered. We encountered a patient with ADPKD who had severe nephromegaly and abdominal swelling that progressed even after starting CAPD. To treat enlarged kidneys in patients with ADPKD, renal transcatheter arterial embolization (TAE) is a therapeutic option. We report the outcome of TAE in our CAPD patient, a 63-year-old Japanese woman who was admitted to our hospital to treat enlarged kidneys 4 years after starting CAPD for end-stage renal disease secondary toADPKD. Residual kidney function was minimal. TAE was performed for both kidneys using platinum microcoils under epidural anesthesia. Six months after TAE, volumes of the left and right kidneys had decreased from 3,037 to 1,440 cm and 5,251 to 1,884 cm, respectively, and the patient’s abdominal distension (with umbilical and inguinal hernias) subsided (Fig 1). Peritoneal dialysis (PD) fluid volume could be increased from 1,200 to 1,600 mL. Weekly Kt/V increased from 1.38 to 1.76, and total creatinine clearance increased from 27.8 to 44.4 L/wk when using 1,600 mL of PD fluid (Fig 1). Prolongation of the duration of PD was achieved. We conclude that renal TAE is a therapeutic option for patients with ADPKD for whom PD fluid volume is limited by nephromegaly.

Correction to: Hypertension Research (2010) 33, 945; doi:10.1038/hr.2010.113 In Table 2 of the above article (advance online publication 8 July 2010 and in the September issue 2010), 3-methylhistidin should have read 3-methylhistidine. The publishers apologize for this and are now happy to correct this mistake.

We have isolated and characterized a novel human and rat organic anion transporter subtype, OATP-D. The isolated cDNA from human brain encodes a polypeptide of 710 amino acids ( Mr76,534) with 12 predicted transmembrane domains. The rat clone encodes 710 amino acids ( Mr76,821) with 97.6% amino acid sequence homology with human OATP-D. Human and rat OATP-D have moderate amino acid sequence homology with LST-1/rlst-1, the rat oatp family, the prostaglandin transporter, and moat1/MOAT1/KIAA0880/OATP-B. Phylogenetic tree analysis revealed that OATP-D is branched in a different position from all known organic anion transporters. OATP-D transports prostaglandin E1( Km48.5 nM), prostaglandin E2( Km55.5 nM), and prostaglandin F2α, suggesting that, functionally, OATP-D encodes a protein that has similar characteristics to those of the prostaglandin transporter. Rat OATP-D also transports prostaglandins. The expression pattern of OATP-D mRNA was abundant mainly in the heart, testis, brain, and some cancer cells. Immunohistochemical analysis further revealed that rat OATP-D is widely expressed in the vascular, renal, and reproductive system at the protein level. These results suggest that OATP-D plays an important role in translocating prostaglandins in specialized tissues and cells.