Language：Japanese   Publisher：(一社)日本透析医学会  

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Sodium magnetic resonance imaging can non-invasively assess sodium distribution, specifically sodium concentration in the countercurrent multiplication system in the kidney, which forms a sodium concentration gradient from the cortex to the medulla, enabling efficient water reabsorption. This study aimed to investigate whether sodium magnetic resonance imaging can detect changes in sodium concentrations under normal conditions in mice and in disease models such as a mouse model with diabetes mellitus. Methods: We performed sodium and proton nuclear magnetic resonance imaging using a 9.4-T vertical standard-bore super-conducting magnet. Results: A condition of deep anesthesia, with widened breath intervals, or furosemide administration in 6-week-old C57BL/6JJcl mice showed a decrease in both tissue sodium concentrations in the medulla and sodium concentration gradients from the cortex to the medulla. Further, sodium magnetic resonance imaging revealed reductions in the sodium concentration of the medulla and in the gradient from the cortex to the medulla in BKS.Cg-Leprdb+/+ Leprdb/Jcl mice at very early type-2 diabetes mellitus stages compared to corresponding control BKS.Cg-m+/m+/Jcl mice. Conclusions: The kidneys of BKS.Cg-Leprdb+/+ Leprdb/Jcl mice aged 6 weeks showed impairments in the countercurrent multiplication system. We propose the utility of 23Na MRI for evaluating functional changes in diabetic kidney disease, not as markers that reflect structural damage. Thus, 23Na MRI may be a potential very early marker for structures beyond the glomerulus; this may prompt intervention with novel efficacious tubule-targeting therapies.

DOI： 10.34067/KID.0000000000000072

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Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: The post-dialysis plasma level of human atrial natriuretic peptide (hANP) reflects the fluid volume in patients on hemodialysis. The threshold hANP level is reportedly 100 pg/mL; however, the clinical usefulness of the threshold hANP level for volume control has not been sufficiently studied. METHODS: We conducted a single-center, retrospective, observational study that included 156 hemodialysis patients without atrial fibrillation. First, we examined the usefulness of the threshold hANP level (100 pg/mL) for predicting hypoxemia due to congestion in a short-term observational study from December 30, 2015 to January 5, 2016. Subsequently, we conducted a 5-year follow-up study wherein the outcomes were hospitalization due to acute heart failure (AHF), development of cardiovascular diseases (CVD), and all-cause death. Finally, we collected echocardiography data to investigate the relationship between cardiac function and hANP. RESULTS: Our short-term observational study showed that patients with an hANP level ≥ 100 pg/mL developed hypoxemia due to congestion (odds ratio, 3.52; 95% confidence interval, 1.06-11.71; P = 0.040). At the 5-year follow-up, patients with an hANP level ≥ 100 pg/mL had significantly higher rates of hospitalization due to AHF, CVD, and all-cause death based on the log-rank test (P = 0.003, P = 0.019, P < 0.001, respectively). Cardiac disfunctions were significantly associated with the high hANP level. CONCLUSIONS: The hANP level is indicative of both fluid volume and cardiac dysfunction. A threshold hANP level of 100 pg/mL can serve as a predictive marker for AHF and a practical indicator for volume control.

DOI： 10.1007/s10157-023-02333-1

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BACKGROUND: The benefits of dietary protein restriction in CKD remain unclear, largely due to inadequate adherence in most clinical trials. We examined whether low-protein rice (LPR) previously developed to reduce the protein content of rice, a major staple food, would help improve adherence to dietary protein restriction. METHODS: This open-label, multicenter, randomized, controlled trial evaluated the efficacy of LPR use for reducing dietary protein intake (DPI) in patients with CKD stages G3aA2-G4. Participants were randomly assigned in a 1:1 ratio to an LPR or control group and were followed up for 24 weeks. Both groups received regular counseling by dietitians to help achieve a target DPI of 0.7 g/kg ideal body weight (IBW) per day. The amount of protein in LPR is about 4% of that in ordinary rice, and the participants in the LPR group were instructed to consume LPR with at least two meals per day. The primary outcome was estimated dietary protein intake (eDPI) determined using the Maroni formula. The secondary outcomes included creatinine clearance (CCr) and urinary protein on the basis of 24-hour urine collection. RESULTS: In total, 51 patients were randomized to either the LPR group or the control group. At baseline, mean age was 62.5 years, 70% were men, mean CCr was 52.0 ml/min, and mean eDPI was 0.99 g/kg IBW per day. At 24 weeks, mean eDPI decreased to 0.80 g/kg IBW per day in the LPR group and to 0.91 g/kg IBW per day in the control group, giving a between-group difference of 0.11 g/kg IBW per day (95% confidence interval, 0.03 to 0.19 g/kg IBW per day; P=0.006). There was no significant between-group difference in CCr, but urinary protein was lower at 24 weeks in the LPR group than in the control group. CONCLUSIONS: LPR is a feasible tool for efficiently reducing DPI in patients with CKD. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: Randomized, Multicenter, Controlled Study for the Efficacy of Low-Protein Rice Diet in Patients with Chronic Kidney Disease, UMIN000015630.

DOI： 10.34067/KID.0002982022

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Language：Japanese   Publisher：(一社)日本腎臓学会  

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AIMS: Megalin, a proximal tubular endocytosis receptor, is excreted in urine in two forms: ectodomain (A-megalin) and full-length (C-megalin). We explored whether urinary megalin levels can be used as independent prognostic biomarkers in the progression of diabetic kidney disease (DKD). METHODS: The associations between baseline urinary A-megalin/creatinine (Cr) and/or C-megalin/Cr levels and the subsequent estimated glomerular filtration rate (eGFR) slope were analyzed using a generalized estimating equation. Patients were categorized into higher or lower groups based on the optimal cutoff values, obtained from a receiver operating characteristic curve, of the two forms of urinary megalin. RESULTS: We retrospectively analyzed 188 patients with type 2 diabetes. The eGFR slopes of the higher A-megalin/Cr and higher C-megalin/Cr groups were - 0.904 and -0.749 ml/min/1.73 m2/year steeper than those of the lower groups, respectively. Moreover, the eGFR slope was -1.888 ml/min/1.73 m2/year steeper in the group with both higher A- and higher C-megalin/Cr than in the other group. These results remained significant when adjusted for known urinary biomarkers (albumin, α1-microglobulin, β2-microglobulin, and N-acetyl-β-d-glucosaminidase). CONCLUSIONS: Urinary A- and C-megalin/Cr levels are likely to be prognostic biomarkers in the progression of DKD independent of other urinary biomarkers.

DOI： 10.1016/j.jdiacomp.2022.108312

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Language：Japanese   Publisher：日本腎臓病薬物療法学会  

CKD患者に対する腎排泄型薬剤の処方は過量投与による副作用リスクが高く、処方監査時には特に注意を要する。病院と診療所では腎機能に対して過量投与が疑われる薬剤の種類が異なる可能性があり、その特徴について調査した。2018年4月から5月に入院した1,630名の中から、除外基準に該当しなかった1,049名の持参薬について、改定45版腎機能別薬剤投与方法一覧に基づき、推奨される投与量よりも過量だった場合に過量投与疑いありと定義した。過量投与疑いがあった患者は66名(6.3%)、過量投与疑いのあった薬剤数は75剤であった。過量投与疑いあり群はCKDステージ2-3群では病院が34薬剤(58%)、CKDステージ4-5群では診療所が10薬剤(63%)を占め、CKDの進行に伴い診療所での過量投与が増加する傾向を認めた。薬効別ではH2遮断薬が11件、糖尿病治療薬が8件、抗アレルギー薬が8件、高尿酸血症治療薬が8件、抗菌薬が7件と過量投与疑いの件数が多かった。糖尿病治療薬の過量投与疑いは病院が有意に多く(P=0.03)、抗精神病薬の過量投与疑いは診療所が有意に多かった(P=0.03)。抗菌薬の過量投与疑いはCKDステージ2-3群において診療所が多い傾向を認めた(P=0.17)。この結果は処方元医療機関の違いにより、腎機能低下時に注意すべき薬剤が異なる可能性を示した。これらを把握することで病院における持参薬の鑑別や保険薬局における処方監際の質を向上させると考えられる。また、過量投与疑いのあった薬剤は、日常的に処方されるものが多かったことから、処方監査時は薬剤の種類を限定せず腎機能を把握しておく必要がある。CKDシールや、院外処方箋への検査値印字、病院と保険薬局の情報共有による薬薬連携により、腎機能の指標となるデータを処方元医療機関もしくは患者本人から確認し調剤を行うことが、薬剤師業務の質を向上させCKD患者における安全な薬物療法を向上できる可能性がある。(著者抄録)

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The number of fractures related to osteoporosis is expected to increase. Therefore, clarifying the risk of acute kidney injury (AKI) associated with each type of anti-osteoporotic drug may avoid discontinuation of osteoporosis pharmacotherapy due to onset of AKI. This cross-sectional study using disproportional analysis and a pharmacovigilance database assessed the risk of AKI with various anti-osteoporotic drugs by analyzing data entered into the US Food and Drug Administration's Adverse Event Reporting System (FAERS) from April 2014 to March 2021 and the Medical Data Vision (MDV) database in Japan in November 2021. All anti-osteoporotic drugs were investigated, including bisphosphonates, selective estrogen receptor modulators, denosumab, romosozumab, abaloparatide, and teriparatide. In the analysis of FAERS data, disproportionality for decreasing AKI was observed for oral ibandronate [reporting odds ratios (ROR) 0.22, 95% confidence interval (CI) 0.09-0.45, P < 0.01], bazedoxifene (ROR 0.26, 95% CI 0.05-0.77, P = 0.01), and intravenous ibandronate (ROR 0.39, 95% CI 0.14-0.86, P = 0.01). In the analysis of the MDV data, the incidence of AKI was lower in patients taking intravenous ibandronate [odds ratio (OR) 0.22, 95% CI 0.06-0.89, P = 0.03], and the incidence of AKI was higher in patients taking oral alendronate (OR 2.40, 95% CI 2.08-2.77, P < 0.01). Risk of AKI may differ even among oral anti-osteoporotic drugs, and the evidence of this association should be assessed further in future drug safety studies. This article is protected by copyright. All rights reserved.

DOI： 10.1002/jcph.2091

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The association between the use of sodium-glucose cotransporter-2 (SGLT-2) inhibitors and the occurrence of drug-induced kidney injury has not been evaluated. This study assessed whether the use of SGLT-2 inhibitors decreases the risk of drug-induced acute kidney injury (AKI) using the US Food and Drug Administration's Adverse Event Reporting System and the Medical Data Vision database. The occurrence of AKI in SGLT-2 inhibitor users and dipeptidyl peptidase-4 (DPP-4) inhibitor users was compared using both databases. In the US Food and Drug Administration's Adverse Event Reporting System analysis, disproportionality for AKI was observed between DPP-4 inhibitor users and SGLT-2 inhibitor users administered nonsteroidal anti-inflammatory drugs (reporting odds ratio, 0.65; 95%CI, 0.48-0.88; P < .01) and thiazide diuretics (reporting odds ratio, 0.78; 95%CI, 0.67-0.90; P < .01). In Medical Data Vision analysis, SGLT-2 inhibitor users administered nonsteroidal anti-inflammatory drugs (odds ratio [OR], 0.46; 95%CI, 0.41-0.53; P < .01), anti-herpes simplex virus drugs (OR, 0.20; 95%CI, 0.07-0.53; P < .01), thiazide diuretics (OR, 0.50; 95%CI, 0.36-0.71, P < .01), and loop diuretics (OR, 0.71; 95%CI, 0.62-0.83; P < .01) had a lower incidence of AKI compared with DPP-4 inhibitor users receiving the same drugs. No differences were observed in the risk of AKI between SGLT-2 and DPP-4 inhibitor users administered vancomycin and cisplatin in both databases. The use of SGLT-2 inhibitors might reduce the risk of drug-induced AKI caused by some drugs.

DOI： 10.1002/jcph.1998

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Language：Japanese   Publisher：Niigata Blood Purification Conference事務局  

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23Na-MRI provides information on Na+ content, and its application in the medical field has been highly anticipated. However, for existing clinical 1H-MRI systems, its implementation requires an additional broadband RF transmitter, dedicated transceivers, and RF coils for Na+ imaging. However, a standard medical MRI system cannot often be modified to perform 23Na imaging. We have developed an add-on crossband RF repeater system that enables 23Na-MRI simply by inserting it into the magnet bore of an existing 1H MRI. The three axis gradient fields controlled by the 1H-MRI system were directly used for 23Na imaging without any deformation. A crossband repeater is a common technique used for amateur radio. This concept was proven by a saline solution phantom and in vivo mouse experiments. This add-on RF platform is applicable to medical 1H MRI systems and can enhance the application of 23Na-MRI in clinical usage.

DOI： 10.2463/mrms.tn.2021-0094

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Language：Japanese   Publisher：新潟県医師会  

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Publishing type：Research paper (scientific journal)   Publisher：Wiley  

DOI： 10.1002/jcph.1964

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Language：English   Publishing type：Research paper (scientific journal)  

Chronic kidney disease (CKD) impairs the anti-inflammatory effects of high-density lipoprotein (HDL) and increases cardiovascular mortality. Though the potential role of dietary interventions to manage HDL is well studied, the clinical trials aimed to increase HDL levels have failed to reduce cardiovascular risk, rendering HDL function to be explored as a more relevant clinical parameter. This study investigates the effects of rice endosperm protein (REP), a plant-based protein, on the anti-inflammatory properties of HDL and renal injury-driven atherosclerosis in comparison with casein, an animal protein. Ten-week-old apolipoprotein E-deficient hyperlipidemic mice underwent uninephrectomy. The mice (n = 6 each) were pair-fed a normal casein-based diet or a REP-based diet (both with 20.0% protein content) for seven weeks. Atherosclerotic lesions were detected by en face Sudan IV staining of the aorta. The number and sizes of the atherosclerotic lesions were significantly lower in the REP-based diet-fed group than the casein-based diet-fed group (p = 0.038). However, the REP-based diet neither elicited an ameliorative effect on kidney function or histology nor impacted the cholesterol profiles. Furthermore, HDL from the REP-based diet-fed mice significantly suppressed the inflammatory cytokine response of human umbilical vein endothelial cells than that from the casein-based diet-fed mice (MCP-1, p = 0.010; IL-6, p = 0.011; IL-1β, p = 0.028). The REP-based diet has a higher potential to lessen the atherosclerotic lesions accelerated by renal mass reduction than a casein-based diet, which could be associated with the anti-inflammatory effects of HDL.

DOI： 10.1080/07315724.2021.1950584

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DOI： 10.1177/10600280211022439

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Language：Japanese   Publisher：(一社)日本腎臓学会  

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Language：Japanese   Publisher：(有)科学評論社  

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Language：Japanese   Publisher：(有)科学評論社  

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Language：English   Publishing type：Research paper (scientific journal)  

INTRODUCTION: The precise blood glucose (BG) profile of hemodialysis patients is unclear, as is the effectiveness of dipeptidyl peptidase-4 (DPP-4) inhibitors in hemodialysis patients with type 2 diabetes. Here, we used continuous glucose monitoring (CGM) to evaluate BG variability in these patients and to assess the efficacy of DPP-4 inhibitors, particularly during hemodialysis sessions and at nighttime (UMIN000012638). METHODS: We examined BG profiles using CGM in 31 maintenance hemodialysis patients with type 2 diabetes. Differences between patients with and without DPP-4 inhibitors (n = 15 and 16, respectively) were analyzed using a linear mixed-effects model to assess changes in glucose levels in 5-min intervals. RESULTS: The model revealed that DPP-4 inhibitor use was significantly associated with suppression of a rapid drop in glucose levels, both with and without adjustment for BG levels at the start of hemodialysis. Moreover, the model revealed that the two groups differed significantly in the pattern of changes in BG levels from 0:00 to 6:55 am. DPP-4 inhibitors suppressed the tendency for subsequent nocturnal hypoglycemia. CONCLUSIONS: This prospective observational exploratory study showed that DPP-4 inhibitors could suppress BG variability during hemodialysis sessions as well as subsequent nocturnal changes in patients with type 2 diabetes. TRIAL REGISTRATION: ClinicalTrials.gov identifier, UMIN000012638.

DOI： 10.1007/s13300-020-00928-5

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Language：Japanese   Publisher：(一社)日本糖尿病学会  

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Language：Japanese   Publisher：(一社)日本腎臓学会  

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Language：Japanese   Publisher：(一社)日本腎臓学会  

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Language：Japanese   Publisher：(一社)日本腎臓学会  

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Language：Japanese   Publisher：新潟医学会  

症例は50歳代、男性。35歳時に、高血圧、心房細動を指摘された。X-6年、うっ血性心不全、大動脈弁輪拡張症にて入院し、翌X-5年3月にBentall手術、MAZE手術が施行された。その際に初めて多発性嚢胞腎、多発性肝嚢胞を指摘された。Cre 1.53mg/dL、eGFR 39mL/min/1.73m2、総腎容積2,421mL(Mayo分類1D)、総肝容積8,614mL(Gigot分類II型)。以後、当院に通院継続したが、X-2年10月にはCre 2.44mg/dL、eGFR 23mL/min/1.73m2、TKV 3,540mL、LV12,674mLと、腎機能、腎腫大、肝腫大はいずれも悪化した。腎嚢胞増大の抑制を目的としてトルバプタン60mgを開始したが、十分な飲水ができず腎機能が悪化し30mgに減量した。動脈塞栓術の適応について、血液透析導入後に慎重に検討する予定であった。X-1年12月、eGFR 15mL/min/1.73m2、未満に至りトルバプタンを中止した。X年1月、胸水の増量、低栄養が進行し入院した。栄養状態が悪化し腎機能も末期腎不全状態まで悪化したため、1ヵ月後に緊急血液透析に導入した。しかし、腹部膨満による呼吸不全からCO2ナルコーシスに陥り、非侵襲的陽圧換気療法でも管理困難であった。透析導入2ヵ月後に死亡した。多発性嚢胞腎、多発性肝嚢胞の嚢胞増大は腹部膨満により低栄養や臓器の圧迫による症状を引き起こす。嚢胞の増大に対する治療は、腎・肝動脈塞栓術、外科的に嚢胞開窓術、またPLDには肝切除術、肝移植術が考慮されるが合併症の割合も低くはない。本例はいずれも十分に検討することができなかったが、多発性嚢胞腎、多発性肝嚢胞の嚢胞増大には、動脈塞栓術か外科的治療の適応について症例毎に慎重に検討すべきである。(著者抄録)

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Language：Japanese   Publisher：(公財)臨床薬理研究振興財団  

軽度〜中等度腎機能障害を有する成人2型糖尿病患者(残存機能ネフロンに過剰代謝負荷がかかっていることが推測される)を対象に、エンパグリフロジンによる腎機能保護作用を検証するとともに尿中メガリン(およびメガリンリガンド分子)の動態を調べ、腎機能保護作用がメガリン機能に関連したものであるか検討した。さらに、尿中メガリンなどの検査がコンパニオン診断として有用であるか、探索的な検討を行った。また、SGLT2阻害薬がメガリンの発現・機能に及ぼす影響についても検討を継続した。臨床試験の被験者51名で、平均年齢は62歳であり、男性が32名であった。2名が有害反応のため脱落したが、6ヵ月後、HbA1cとBMIが減少した。現在、メガリンを含む尿中バイオマーカーの推移について解析を行っている。ダパグリフロジン、エンパグリフロジンを投与されたマウスでは尿中の糖排泄増加を認めたが血糖値に差は認められなかった。免疫組織化学染色では近位尿細管におけるメガリンの染色性が低下していることが確認された。またウエスタンブロット法において、メガリンの蛋白がvehicle群と比較して低下していることが認められた。リアルタイムRT-PCRにおいてもメガリンmRNAがvehicle群と比較して低下していることが確認された。ダパグリフロジンを添加されたIRPTCではメガリン蛋白の低下が認められ、mRNAの低下も認められた。

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Obesity and related disorders, which are increasing in adults worldwide, are closely linked to childhood diet and are associated with chronic inflammation. Rice endosperm protein (REP) intake during adulthood has been reported to improve lipid metabolism and suppress the progression of diabetic kidney disease in animal models. However, the effects of REP intake during childhood on adulthood health are unclear. Therefore, we used a mouse model to experimentally investigate the preconditioning effects of REP intake during childhood on the development of obesity and related disorders in adulthood. Male C57BL/6J mice were pair-fed a normal-fat diet containing casein or REP during the juvenile period and then a high-fat diet (HFD) containing casein or REP during adulthood. Mice fed REP during the juvenile period showed better body weight, blood pressure, serum lipid profiles, lipopolysaccharide (LPS)-binding protein levels, and glucose tolerance in adulthood than those fed casein during the juvenile period. HFD-induced renal tubulo-glomerular alterations and hepatic microvesicular steatosis were less evident in REP-fed mice than in casein-fed ones. REP intake during the juvenile period improved HFD-induced dysbiosis (i.e., Escherichia genus proliferation and reduced gut microbiota diversity), thereby suppressing endotoxin-related chronic inflammation. Indeed, REP-derived peptides showed antibacterial activity against Escherichia coli, a major producer of LPS. In conclusion, REP supplementation during the juvenile period may regulate the gut microbiota and thus suppress the development of obesity and related disorders in adulthood in mice.

DOI： 10.3390/nu11122919

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BACKGROUND: Cisplatin is a potent chemotherapeutic agent used to treat a variety of solid tumors. One of the major side effects of cisplatin is dose-limiting nephrotoxicity. We recently demonstrated that the renal uptake of cisplatin and resultant cisplatin-induced nephrotoxicity are mediated in part by megalin, an endocytic receptor in proximal tubule epithelial cells (PTECs). We also developed sandwich enzyme-linked immunosorbent assays to measure the megalin ectodomain (A-megalin) and full-length megalin (C-megalin) in urine using monoclonal antibodies against the amino- and carboxyl-termini of megalin, respectively. The present study examined the correlation of urinary megalin level with cisplatin-induced nephrotoxicity and its utility as a biomarker in patients with thoracic cancer. METHODS: This prospective observational study involved 45 chemotherapy-naïve patients scheduled to receive chemotherapy with ≥60 mg/m2 cisplatin for histologically diagnosed small cell lung cancer, non-small cell lung cancer, or malignant pleural mesothelioma. Before and after the first course of chemotherapy, we measured urinary A- and C-megalin and other markers of PTEC injury, such as N-acetyl-β-D-glucosaminidase, α1-microglobulin, β2-microglobulin, neutrophil gelatinase-associated lipocalin, and liver-type fatty acid-binding protein, and compared the values with the change in the estimated glomerular filtration rate (eGFR) and clinical risk factors for renal impairment. RESULTS: A negative correlation was found between baseline urinary A-megalin levels and change in eGFR (r = - 0.458, P = 0.002). According to Kaplan-Meier survival curves, eGFR decline was associated with the baseline urinary A-megalin quartile (P = 0.038). In addition, according to the hazard ratios (HRs) for eGFR decline > 10 mL/min/1.73 m2 calculated using a Cox proportional hazard model, the highest quartile had a significantly higher risk of eGFR decline compared with the lowest quartile (HR 7.243; 95% confidence interval 1.545-33.962). Other baseline urinary markers showed no correlation with eGFR decline. CONCLUSIONS: This is the first report demonstrating that prechemotherapy urinary A-megalin levels are correlated with the development of cisplatin-induced nephrotoxicity. This finding has clinical implications for the identification of patients at risk for cisplatin-induced nephrotoxicity and the development of possible prophylactic therapies.

DOI： 10.1186/s12885-019-6398-2

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BACKGROUND: Dietary acid load has been suggested to mediate the progression of chronic kidney disease (CKD). However, it is unclear what kinds of foods are actually associated with dietary acid load in patients with CKD. The self-administered diet history questionnaire (DHQ), which semi-quantitatively assesses the dietary habits of Japanese individuals through 150 question items, can estimate average daily intake of various foods and nutrients during the previous month. Using the DHQ, we investigated the association of dietary acid load with CKD progression. We also analyzed the kinds of food that significantly affect dietary acid load. METHODS: Subjects were 96 outpatients with CKD (average estimated glomerular filtration rate [eGFR], 53.0 ± 18.1 ml/min/1.73 m2) at Niigata University Hospital, who had completed the DHQ in 2011. We calculated net endogenous acid production (NEAP) from potassium and protein intake evaluated by the DHQ in order to assess dietary acid load. CKD progression was assessed by comparing eGFR between 2008 and 2014. RESULTS: NEAP was not correlated with protein intake (r = 0.088, p = 0.398), but was negatively correlated with potassium intake (r = - 0.748, p < 0.001). Reduction in eGFR from 2008 to 2014 was estimated to be significantly greater in patients with higher NEAP (NEAP > 50.1 mEq/day, n = 45) than in those with lower NEAP (NEAP ≤50.1 mEq/day, n = 50) by 5.9 (95% confidence interval [95%CI], 0.1 to 11.6) ml/min/1.73 m2. According to multiple logistic regression analysis, higher NEAP was significantly associated with lower intake of fruits (odds ratio [OR], 6.454; 95%CI, 2.19 to 19.00), green and yellow vegetables (OR, 5.18; 95%CI, 1.83 to14.66), and other vegetables (OR, 3.87; 95%CI, 1.29 to 11.62). CONCLUSIONS: Elevated NEAP could be a risk factor for CKD progression. Low intake of fruits and vegetables would increase dietary acid load and might affect the progression of renal dysfunction in Japanese CKD patients.

DOI： 10.1186/s12882-019-1591-8

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Language：Japanese   Publisher：(一社)日本腎臓学会  

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Language：Japanese   Publisher：(一社)日本糖尿病学会  

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DOI： 10.1016/j.numecd.2018.02.020

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Language：Japanese   Publisher：(一社)日本糖尿病学会  

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Language：Japanese   Publisher：(一社)日本糖尿病学会  

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Language：Japanese   Publisher：(一社)日本糖尿病学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Tokyo  

Background: It is well known that atrophic renal changes are associated with chronic kidney disease (CKD) progression, but conventional diagnostic imaging methods such as noncontrast-enhanced computed tomography and magnetic resonance imaging (MRI) have been insufficient for precisely assessing kidney function because they cannot clearly distinguish between the medulla and cortex. Hence, here we used noncontrast-enhanced steady-state free precession (SSFP) MRI with a spatially selective inversion recovery (IR) pulse to improve visibility for renal corticomedullary differentiation and evaluated the association between morphological parameters and kidney function in patients with CKD. Methods: Kidney corticomedullary contrast ratio, cortical and medullary areas, and minimal cortical thickness of 107 patients with CKD G1–G5 were measured using SSFP MRI with a spatially selective IR pulse and the association between these morphological parameters and kidney function were evaluated. Results: Corticomedullary contrast ratio was significantly improved on SSFP MRI compared with conventional in-phase T1-weighted gradient-echo MRI and positively correlated with estimated glomerular filtration ratio (eGFR), raw eGFR, and 24-h creatinine clearance. The medullary and cortical areas and minimal cortical thickness also positively correlated with those of kidney functional markers and the age. In patients with CKD and diabetes mellitus (DM), the correlation coefficients between raw eGFR and morphological parameters were higher than those in patients without DM, while minimal cortical thickness was larger in CKD patients with DM with a raw eGFR ≥ 45 mL/min. Conclusion: Kidney morphological parameters measured with SSFP MRI were clearly correlated with kidney function in patients with CKD, including those with advanced kidney dysfunction.

DOI： 10.1007/s10157-017-1413-x

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BACKGROUND: Our aim was to evaluate lipid trafficking and inflammatory response of macrophages exposed to lipoproteins from subjects with moderate to severe chronic kidney disease (CKD), and to investigate the potential benefits of activating cellular cholesterol transporters via liver X receptor (LXR) agonism. METHODS: LDL and HDL were isolated by sequential density gradient ultracentrifugation of plasma from patients with stage 3-4 CKD and individuals without kidney disease (HDLCKD and HDLCont, respectively). Uptake of LDL, cholesterol efflux to HDL, and cellular inflammatory responses were assessed in human THP-1 cells. HDL effects on inflammatory markers (MCP-1, TNF-α, IL-1β), Toll-like receptors-2 (TLR-2) and - 4 (TLR-4), ATP-binding cassette class A transporter (ABCA1), NF-κB, extracellular signal regulated protein kinases 1/2 (ERK1/2) were assessed by RT-PCR and western blot before and after in vitro treatment with an LXR agonist. RESULTS: There was no difference in macrophage uptake of LDL isolated from CKD versus controls. By contrast, HDCKD was significantly less effective than HDLCont in accepting cholesterol from cholesterol-enriched macrophages (median 20.8% [IQR 16.1-23.7] vs control (26.5% [IQR 19.6-28.5]; p = 0.008). LXR agonist upregulated ABCA1 expression and increased cholesterol efflux to HDL of both normal and CKD subjects, although the latter continued to show lower efflux capacity. HDLCKD increased macrophage cytokine response (TNF-α, MCP-1, IL-1β, and NF-κB) versus HDLCont. The heightened cytokine response to HDLCKD was further amplified in cells treated with LXR agonist. The LXR-augmentation of inflammation was associated with increased TLR-2 and TLR-4 and ERK1/2. CONCLUSIONS: Moderate to severe impairment in kidney function promotes foam cell formation that reflects impairment in cholesterol acceptor function of HDLCKD. Activation of cellular cholesterol transporters by LXR agonism improves but does not normalize efflux to HDLCKD. However, LXR agonism actually increases the pro-inflammatory effects of HDLCKD through activation of TLRs and ERK1/2 pathways.

DOI： 10.1186/s12882-018-0814-8

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

In maintenance hemodialysis (MHD) patients, low protein intake is associated with protein-energy wasting, a risk factor that affects outcome. However, increased protein intake may lead to hyperphosphatemia and hyperkalemia, which are also mortality risk factors. Here, we evaluated the safety and effects of purified rice endosperm protein (REP), which contains less phosphorus and potassium than soy and casein proteins, as a supplemental protein source for MHD patients. This randomized, double-blind, placebo-controlled, crossover pilot study of REP supplementation (5 g/day x 4 weeks) was carried out in 50 Japanese adult MHD patients (1 dropped out); the primary outcome was the change in the urea kinetic-based normalized protein catabolic rate (nPCR), an indicator of protein intake in MHD patients. Intention-to-treat analyses of 24 patients in the REP-first group and 25 in the placebo-first group showed that REP supplementation increased nPCR significantly by 0.07 g/kg/day (95% confidence interval, 0.03-0.11), whereas changes in serum phosphorus and potassium concentrations were not different from the placebo. REP supplementation did not show a significant effect on other nutritional or metabolic parameters and no specific complications. In conclusion, purified REP with efficient bioavailability may be safe and useful for dietary supplementation in MHD patients.

DOI： 10.1038/s41598-017-18340-8

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Language：Japanese   Publisher：新潟急性血液浄化研究会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC NEPHROLOGY  

Nephrotoxicity induced by antimicrobial or anticancer drugs is a serious clinical problem. Megalin, an endocytic receptor expressed at the apical membranes of proximal tubules, mediates the nephrotoxicity of aminoglycosides and colistin, key antimicrobials for multidrug-resistant organisms. The mechanisms underlying the nephrotoxicity induced by vancomycin, an antimicrobial for methicillin-resistant Staphylococcus aureus, and cisplatin, an important anticancer drug, are unknown, although the nephrotoxicity of these drugs and gentamicin, an aminoglycoside, is suppressed experimentally with cilastatin. In the clinical setting, cilastatin has been used safely to suppress dehydropeptidase-I-mediated renal metabolism of imipenem, a carbapenem antimicrobial, and thereby limit tubular injury. Here, we tested the hypothesis that cilastatin also blocks megalin-mediated uptake of vancomycin, cisplatin, colistin, and aminoglycosides, thereby limiting the nephrotoxicity of these drugs. Quartz crystal microbalance analysis showed that megalin also binds vancomycin and cisplatin and that cilastatin competes with megalin for binding to gentamicin, colistin, vancomycin, and cisplatin. In kidney specific mosaic megalin knockout mice treated with colistin, vancomycin, or cisplatin, the megalin-replete proximal tubule epithelial cells exhibited signs of injury, whereas the megalin-deficient cells did not. Furthermore, concomitant cilastatin administration suppressed colistin-induced nephrotoxicity in C57BL/6J mice. Notably, cilastatin did not inhibit the antibacterial activity of gentamicin, colistin, or vancomycin in vitro, just as cilastatin did not affect the anticancer activity of cisplatin in previous studies. In conclusion, megalin blockade with cilastatin efficiently suppresses the nephrotoxicity induced by gentamicin, colistin, vancomycin, or cisplatin. Cilastatin may be a promising agent for inhibiting various forms of drug-induced nephrotoxicity mediated via megalin in the clinical setting.

DOI： 10.1681/ASN.2016060606

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER DIABETES ASSOC  

Efficient biomarkers for diabetic nephropathy (DN) have not been established. Using ELISA, we found previously that urinary levels of full-length megalin (C-megalin), a multiligand endocytic receptor in proximal tubules, was positively correlated with DN progression in patients with type 2 diabetes mellitus (T2DM). Here, we found that urinary extracellular vesicle (UEV) excretion and C-megalin content in UEVs or in their exosomal fraction increased along with the progression of the albuminuric stages in patients with T2DM. Cultured immortalized rat proximal tubule cells (IRPTCs) treated with fatty acid-free BSA or advanced glycation end product-modified BSA (AGE-BSA), endocytic ligands of megalin, increased EV excretion, and their C-megalin content. C-megalin excretion from IRPTCs via extracellular vesicles was significantly blocked by an exosome-specific inhibitor, GW4869, indicating that this excretion is mainly exocytosis-mediated. AGE-BSA treatment of IRPTCs caused apparent lysosomal dysfunction, which stimulated multivesicular body formation, resulting in increased exosomal C-megalin excretion. In a high-fat diet-induced, megalin-mediated kidney injury model in mice, urinary C-megalin excretion also increased via UEVs. Collectively, exocytosis-mediated urinary C-megalin excretion is associated with the development and progression of DN in patients with T2DM, particularly due to megalin-mediated lysosomal dysfunction in proximal tubules, and hence it could be a candidate biomarker linked with DN pathogenesis.

DOI： 10.2337/db16-1031

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Language：Japanese   Publisher：(一社)日本腎臓学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC INTERNAL MEDICINE  

Objective The administration of glucocorticoids usually causes a mild increase in fasting glucose levels and a greater dose-dependent increase in postprandial values in patients without pre-existing diabetes mellitus. Patients with persistent hyperglycemia due to glucocorticoid therapy sometimes require insulin therapy, which might result in increased weight gain and more episodes of hypoglycemia, some of which are severe. On the other hand, scant evidence is available on the efficacy of oral hypoglycemic agents in treating glucocorticoid-induced diabetes. In this study, we evaluated the efficacy of dipeptidyl peptidase (DPP)-4 inhibitors in patients with glucocorticoid-induced diabetes by continuous glucose monitoring (CGM).
Methods We examined the glycemic profiles using CGM at baseline and 1-4 weeks after initiating DPP-4 inhibitor treatment in patients with newly developed glucocorticoid-induced diabetes.
Results Eleven patients who had been diagnosed with kidney disease or other diseases with renal involvement were recruited for the present retrospective study. After starting DPP-4 inhibitors, the mean and standard deviation (SD) of the glucose level, and the mean amplitude of glycemic excursion (MAGE) were significantly improved in comparison to baseline. Furthermore, the area over the curve (AOC) for the glucose levels &lt;70 mg/dL was not increased in comparison to baseline after the initiation of DPP-4 inhibitor treatment. The results indicate that the treatment of patients with glucocorticoid-induced diabetes using DPP-4 inhibitors can minimize the risk of hypoglycemia and reduce glucose variability.
Conclusion DPP-4 inhibitors are potentially useful for blood glucose control in patients with glucocorticoid-induced diabetes.

DOI： 10.2169/internalmedicine.8296-16

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Language：Japanese   Publisher：新潟急性血液浄化研究会  

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Language：Japanese   Publisher：(一社)日本腎臓学会  

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Language：Japanese   Publisher：(一社)日本腎臓学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER SOC NEPHROLOGY  

Obesity, an important risk factor for metabolic syndrome (MetS) and cardiovascular disease, is often complicated by CKD, which further increases cardiovascular risk and causes ESRD. To elucidate the mechanism underlying this relationship, we investigated the role of the endocytic receptor megalin in proximal tubule epithelial cells (PTECs). We studied a high-fat diet (HFD)-induced obesity/MetS model using kidney-specific mosaic megalin knockout (KO) mice. Compared with control littermates fed a normal-fat diet, control litter mates fed an HFD for 12 weeks showed autolysosomal dysfunction with autophagy impairment and increased expression of hypertrophy, lipid peroxidation, and senescence markers in PTECs of the S2 segment, peritubular capillary rarefaction with localized interstitial fibrosis, and glomerular hypertrophy with mesangial expansion. These were ameliorated in HFD-fed megalin KO mice, even though these mice had the same levels of obesity, dyslipidemia, and hyperglycemia as HFD-fed control mice. Intravital renal imaging of HFD-fed wild-type mice also demonstrated the accumulation of autofluorescent lipofuscin-like substances in PTECs of the S2 segment, accompanied by focal narrowing of tubular lumens and peritubular capillaries. In cultured PTECs, fatty acid-rich albumin induced the increased expression of genes encoding PDGF-B and monocyte chemoattractant protein-1 via megalin, with large (auto)lysosome formation, compared with fatty acid-depleted albumin. Collectively, the megalin-mediated endocytic handling of glomerular-filtered (lipo)toxic substances appears to be involved primarily in hypertrophic and senescent PTEC injury with autophagy impairment, causing peritubular capillary damage and retrograde glomerular alterations in HFD-induced kidney disease. Megalin could be a therapeutic target for obesity/MetS-related CKD, independently of weight, dyslipidemia, and hyperglycemia modification.

DOI： 10.1681/ASN.2015020190

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Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

DOI： 10.1186/s40795-016-0065-7

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Language：Japanese   Publisher：新潟急性血液浄化研究会  

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Language：English   Publisher：AMER DIABETES ASSOC  

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Language：Japanese   Publisher：新潟医学会  

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Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2015&ichushi_jid=J00990&link_issn=&doc_id=20150811080015&doc_link_id=%2Fdg3nigta%2F2015%2Fs12905%2F008%2F0290-0290%26dl%3D0&url=https%3A%2F%2Fwww.medicalonline.jp%2Fjamas.php%3FGoodsID%3D%2Fdg3nigta%2F2015%2Fs12905%2F008%2F0290-0290%26dl%3D0&type=MedicalOnline&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00004_2.gif

Language：English   Publishing type：Research paper (scientific journal)   Publisher：W B SAUNDERS CO-ELSEVIER INC  

Objectives. Our aim was to determine if chronic kidney disease (CKD) occurring in childhood impairs the normally vasoprotective functions of high-density lipoproteins (HDLs).
Materials and methods. HDLs were isolated from children with end-stage renal disease on dialysis (ESRD), children with moderate CKD and controls with normal kidney function. Macrophage response to HDLs was studied as expression of inflammatory markers (MCP-1, TNF-alpha, IL-1 beta) and chemotaxis. Human umbilical vein endothelial cells were used for expression of adhesion molecules (ICAM-1, VCAM-1, E-selectin) and adhesion. Cellular proliferation, apoptosis, and necrosis of endothelial cells were measured by MTS/PMS reagent-based assay, flow cytometry, and ELISA. Cholesterol efflux was assessed by gas chromatographic measurements of cholesterol in macrophages exposed to HDLs.
Results. Compared with HDLControl, HDLCKD and HDLESRD heightened the cytokine response and disrupted macrophage chemotaxis. HDLControl reduced endothelial expression of ICAM-1, VCAM-1, E-selectin, whereas HDLCKD and HDLESRD were less effective and showed reduced capacity to protect endothelial cells against monocyte adhesion. Compared with a dramatically enhanced endothelial proliferation following injurious stimulus by HDLControl, neither HDLCKD nor HDLESRD caused proliferative effects. HDLs of all three groups were equally protective against apoptosis assessed by flow cytometry and cleaved caspase-3 activity. Compared to HDLControl, HDLCKD and HDLESRD trended toward reduced capacity as cholesterol acceptors.
Conclusion. CKD in children impairs HDL function. Even in the absence of long-standing and concomitant risk factors, CKD alters specific HDL functions linked to control of inflammation and endothelial responses. (C) 2015 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.metabol.2014.10.020

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Language：Japanese   Publisher：新潟急性血液浄化研究会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

Objectives This study examined the functionality of high-density lipoprotein (HDL) in individuals with end-stage renal disease on dialysis (ESRD-HD).
Background The high rate of cardiovascular disease (CVD) in chronic kidney disease is not explained by standard risk factors, especially in patients with ESRD-HD who appear resistant to benefits of statin therapy. HDL is antiatherogenic because it extracts tissue cholesterol and reduces inflammation.
Methods Cellular cholesterol efflux and inflammatory response were assessed in macrophages exposed to HDL of patients with ESRD-HD or controls.
Results HDL from patients with ESRD-HD was dramatically less effective than normal HDL in accepting cholesterol from macrophages (median 6.9%; interquartile range [IQR]: 1.4% to 10.2%) versus control (median 14.9%; IQR: 9.8% to 17.8%; p &lt; 0.001). The profound efflux impairment was also seen in patients with ESRD-HD and diabetes compared with patients with diabetes without renal disease (median 8.1%; IQR: 3.3% to 12.9%) versus control (median 13.6%; IQR: 11.0% to 15.9%; p = 0.009). In vitro activation of cellular cholesterol transporters increased cholesterol efflux to both normal and uremic HDL. HDL of patients with ESRD-HD had reduced anti-chemotactic ability and increased macrophage cytokine response (tumor necrosis factor-alpha, interleukin-6, and interleukin-1-beta). HDL of patients with ESRD-HD on statin therapy had reduced inflammatory response while maintaining impaired cholesterol acceptor function. Interestingly, impaired HDL-mediated efflux did not correlate with circulating C-reactive protein levels or cellular inflammatory response.
Conclusions These findings suggest that abnormal HDL capacity to mediate cholesterol efflux is a key driver of excess CVD in patients on chronic hemodialysis and may explain why statins have limited effect to decrease CV events. The findings also suggest cellular cholesterol transporters as potential therapeutic targets to decrease CV risk in this population. (J Am Coll Cardiol 2012;60:2372-9) (C) 2012 by the American College of Cardiology Foundation

DOI： 10.1016/j.jacc.2012.09.013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER DIABETES ASSOC  

OBJECTIVE-Megalin, an endocytic receptor in proximal tubule cells, is involved in the mechanisms of albuminuria in diabetic nephropathy (DN). To develop efficient novel biomarkers associated with the pathogenesis of DN, we investigated urinary megalin excretion in type 2 diabetes.
RESEARCH DESIGN AND METHODS-Sandwich enzyme-linked immunosorbent assay systems were established with monoclonal antibodies against the NH2 (amino [A]-megalin assay) and CO OH (C-megalin assay) termini of megalin to analyze urinary forms of megalin in 68 patients with type 2 diabetes.
RESULTS-The A-megalin assay mainly detected a megalin ectodomain form in the soluble urinary fraction, whereas the C-megalin assay identified a full-length form in both soluble and insoluble fractions. Urinary C-megalin levels were significantly high in patients with normoalbuminuria, were elevated in line with increased albuminuria, and showed a better association with estimated glomerular filtration rate (eGFR) (&lt;60 mL/min/1.73 m(2)) than did urinary albumin. In contrast, urinary A-megalin levels were increased in patients with normo- and microalbuminuria but not in those with macroalbuminuria. Urinary C-megalin levels were also positively associated with plasma inorganic phosphate and negatively with hemoglobin levels in those showing no features of bleeding and not taking vitamin D analogs, phosphate binders, or erythropoiesis-stimulating agents.
CONCLUSIONS-Urinary full-length megalin excretion as measured by the C-megalin assay is well associated with reduced eGFR and linked to the severity of DN, phosphate dysregulation, and anemia, whereas urinary excretion of megalin ectodomain as measured by the A-megalin assay may be associated with distinctive mechanisms of earlier DN in type 2 diabetes.

DOI： 10.2337/dc11-1684

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：LIPPINCOTT WILLIAMS & WILKINS  

Objective-Angiotensin II is a major determinant of atherosclerosis. Although macrophages are the most abundant cells in atherosclerotic plaques and express angiotensin II type 1 receptor (AT1), the pathophysiologic role of macrophage AT1 in atherogenesis remains uncertain. We examined the contribution of macrophage AT1 to accelerated atherosclerosis in an angiotensin II-responsive setting induced by uninephrectomy (UNx).
Methods and Results-AT1(-/-) or AT1(+/+) marrow from apolipoprotein E deficient (apoE(-/-)) mice was transplanted into recipient apoE-/- mice with subsequent UNx or sham operation: apoE(-/-)/AT1(+/+) -&gt; 3apoE(-/-) +sham; apoE(-/-)/AT1(+/+) 3apoE(-/-) +UNx; apoE(-/-)/AT1(-/-) -&gt; 3apoE(-/-) +sham; apoE(-/-)/AT1(-/-) -&gt; 3apoE(-/-) +UNx. No differences in body weight, blood pressure, lipid profile, and serum creatinine were observed between the 2 UNx groups. ApoE(-/-)/AT1(+/+) 3apoE(-/-) +UNx had significantly more atherosclerosis (16907 +/- 21473 versus 116071 +/- 8180 mu m(2), P &lt; 0.05). By contrast, loss of macrophage AT1 which reduced local AT1 expression, prevented any effect of UNx on atherosclerosis (77174 +/- 9947 versus 75714 +/- 11333 mu m(2), P = NS). Although UNx did not affect total macrophage content in the atheroma, lesions in apoE(-/-)/AT1(-/-) 3apoE(-/-) +UNx had fewer classically activated macrophage phenotype (M1) and more alternatively activated phenotype (M2). Further, UNx did not affect plaque necrosis or apoptosis in apoE(-/-)/AT1(-/-) 3apoE(-/-) whereas it significantly increased both (by 2- and 6-fold, respectively) in apoE(-/-)/AT1(+/+) 3apoE(-/-) mice. Instead, apoE(-/-)/AT1(-/-) 3apoE(-/-) had 5-fold-increase in macrophage-associated apoptotic bodies, indicating enhanced efferocytosis. In vitro studies confirmed blunted susceptibility to apoptosis, especially in M2 macrophages, and a more efficient phagocytic function of AT1(-/-) macrophages versus AT1(+/+).
Conclusion-AT1 receptor of bone marrow-derived macrophages worsens the extent and complexity of renal injury-induced atherosclerosis by shifting the macrophage phenotype to more M1 and less M2 through mechanisms that include increased apoptosis and impaired efferocytosis. (Arterioscler Thromb Vasc Biol. 2011;31:2856-2864.)

DOI： 10.1161/ATVBAHA.111.237198

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Vitamin D deficiency is associated with various medical conditions including musculoskeletal disorders, infection, metabolic diseases, and cardiovascular disease. Megalin and cubilin, endocytic receptors in proximal tubule cells, are involved in the reabsorption of vitamin D binding protein from glomerular filtrates and the subsequent intracellular conversion of 25-hydroxyvitamin D-3 to biologically active 1 alpha,25-dihydroxyvitamin D-3. Dysfunction of these receptors, which is commonly found in patients with diabetic nephropathy, even at early stages, may explain why vitamin D deficiency is often complicated in these patients. Therapeutic strategies to protect the functions of these receptors from injury could be used to prevent vitamin D deficiency and its related disorders.

DOI： 10.1111/j.1744-9987.2011.00920.x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Expression and function of megalin, an endocytic receptor in proximal tubule cells (PTCs), are reduced in diabetic nephropathy, involved in the development of proteinuria/albuminuria. Lipopolysaccharide (LPS) is chronically increased in diabetic sera, by the mechanism called metabolic endotoxemia. We investigated low-level LPS-mediated signaling that regulates megalin expression in immortalized rat PTCs (IRPTCs). Incubation of the cells with LPS (10 ng/ml) for 48 h suppressed megalin protein expression and its endocytic function. TNF-alpha mRNA expression was increased by LPS treatment, and knockdown of the mRNA with siRNA inhibited LPS-mediated downregulation of megalin mRNA expression at the 24-h time point. Incubation of IRPTCs with exogenous TNF-alpha also suppressed megalin mRNA and protein expression at the 24- and 48-h time points, respectively. MEK1 inhibitor PD98059 competed partially but significantly TNF-alpha-mediated downregulation of megalin mRNA expression. Collectively, low-level LPS-mediated TNF-alpha-ERK1/2 signaling pathway is involved in downregulation of megalin expression in IRPTCs. (C) 2011 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2011.02.118

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DOI： 10.4061/2011/957164

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Megalin plays a critical role in the endocytosis of albumin and other filtered low-molecular-weight proteins. Here we studied the interaction between megalin and Disabled-2 (Dab2), an adaptor protein that binds to the cytoplasmic domain of megalin and appears to control its trafficking. We co-immunoprecipitated megalin and Dab2 from cultured proximal tubule cells and identified the proteins by liquid chromatography and tandem mass spectrometry. We found two proteins associated with the megalin/Dab2 complex, nonmuscle myosin heavy chain IIA (NMHC-IIA) and beta-actin. Subcellular fractionation followed by sucrose velocity gradient separation showed that megalin, Dab2, and NMHC-IIA existed as a complex in the same endosomal fractions. In vitro pull-down assays demonstrated that NMHC-IIA was bound to the carboxyl-terminal region of Dab2, but not to megalin&apos;s cytoplasmic domain. We then transfected COS-7 cells with plasmids that induced the expression of Dab2, NMHC-IIA, and the megalin minireceptor, a truncated form of megalin. Co-immunoprecipitation studies showed that the minireceptor and NMHC-IIA co-immunoprecipitated only with Dab2. Furthermore, the uptake of (125)I-lactoferrin, an endocytic ligand of megalin, by rat yolk sac-derived megalin-expressing L2 cells was inhibited by blebbistatin, a specific inhibitor of nonmuscle myosin II. Our study shows that NMHC-IIA is functionally linked to megalin by interaction with Dab2 and is likely involved in megalin-mediated endocytosis in proximal tubule cells. Kidney International (2009) 75, 1308-1315; doi:10.1038/ki.2009.85; published online 1 April 2009

DOI： 10.1038/ki.2009.85

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ENDOCRINE SOC  

Impairment of proximal tubular endocytosis of glomerular-filtered proteins including albumin results in the development of proteinuria/albuminuria in patients with chronic kidney disease. However, the mechanisms regulating the proximal tubular function are largely unknown. This study aimed to investigate the role of angiotensin II type 1A receptor (AT(1A)R)- and insulin-mediated signaling pathways in regulating the expression of megalin, a multiligand endocytic receptor in proximal tubule cells (PTCs). Opossum kidney PTC-derived OK cells that stably express rat AT(1A)R but are deficient in endogenous angiotensin II receptors (AT(1A)R-OK cells) were used for this study. Treatment of the cells with angiotensin II suppressed mRNA and protein expression of megalin at 3- and 24-h incubation time points, respectively. Cellular uptake and degradation of albumin and receptor-associated protein, megalin&apos;s endocytic ligands were suppressed 24 h after angiotensin II treatment. The AT(1A)R-mediated decrease in megalin expression was partially prevented by ERK inhibitors. Insulin competed with the AT(1A)R-mediated ERK activation and decrease in megalin expression. Inhibitors of phosphatidylinositol 3- kinase (PI3K), a major component of insulin signaling, also suppressed megalin expression, and activation of the insulin receptor substrate (IRS)/PI3K system was prevented by angiotensin II. Collectively the AT(1A)R-mediated ERK signaling is involved in suppressing megalin expression in the OK cell line, and insulin competes with this pathway. Conversely, the insulin-IRS/PI3K signaling, with which angiotensin II competes, tends to stimulate megalin expression. In conclusion, there is AT(1A)R- and insulin-mediated competitive signaling cross talk to regulate megalin expression in cultured PTCs. (Endocrinology 150: 871 - 878, 2009)

DOI： 10.1210/en.2008-0886

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS INC ELSEVIER SCIENCE  

Serum levels of cystatin C, an endogenous cysteine protemase inhibitor, are often used as an indicator of glomerular filtration rate. Although it is known that cystatin C is filtered by glomeruli and metabolized in proximal tubule cells (PTC), the precise molecular mechanism underlying this process is undetermined. Using quartz-crystal microbalance analyses, we demonstrate that cystatin C binds directly to megalin, an endocytic receptor in PTC, in a Ca(+)-dependent manner. We also find that cystatin C is endocytosed specifically via megalin in rat yolk sac epithelium-derived L2 cells which share a variety of characteristics with PTC. Finally, it? vivo studies using kidney-specific megalin knockout mice provide evidence that megalin mediates proximal tubular uptake of cystatin C. We conclude that megalin is an endocytic receptor of cystatin C in PTC. (c) 2007 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.bbrc.2007.04.072

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KARGER  

Background/Aims: Mutations of the endosomal chloride/ proton exchanger gene, CLCN5, cause Dent's disease, an X-linked recessive proximal tubular disorder. The renal endocytic system was found to be affected in clcn5 knockout mice. However, the impaired endocytic machinery of Dent's disease patients has not been thoroughly investigated. Methods: The CLCN5 gene was sequenced in a Japanese patient with Dent's disease and his family. The loss-of-function phenotype of the missense CLCN5 mutation was investigated by gene expression in Xenopus oocytes and CHO cells. Immunohistochemical analysis was performed on kidney biopsy specimens for endocytic machinery proteins, megalin, cubilin, and disabled-2 (Dab2) in proximal tubules. Results: Genomic analysis revealed a novel G-to-A transition at the first nucleotide of the 333rd codon of CLCN5, causing a substitution of glycine with arginine. Inefficient expression of the mutant gene in Xenopus oocytes resulted in abolished chloride currents. Impaired N-glycosylation of the mutant protein was evident in the DNA-transfected CHO cells. Proximal tubular expression of megalin, cubilin, and Dab2 was markedly reduced and irregular staining in some portions was observed in the patient compared with controls. Conclusions: A novel G333R CLCN5 mutation caused defective expression of megalin, cubilin, and Dab2 in a patient with Dent's disease. Copyright (c) 2007 S. Karger AG, Basel.

DOI： 10.1159/000111253

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DOI： 10.1159/000111253

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-BLACKWELL  

Megalin is an endocytic receptor on the apical membranes of proximal tubule cells (PTC) in the kidney, and is involved in the reabsorption and metabolism of various proteins that have been filtered by glomeruli. Patients with diabetes, especially type 2 diabetes, or metabolic syndrome are likely to have elevated serum levels of advanced glycation end products, liver-type fatty acid binding protein, angiotensin 11, insulin and leptin, and renal metabolism of these proteins is potentially overloaded. Some of these proteins are themselves nephrotoxic, while others are carriers of nephrotoxic molecules. Megalin is involved in the proximal tubular uptake of these proteins. We hypothesize that megalin-mediated metabolic overload in PTC leads to compensatory cellular hypertrophy and sustained Na(+) reabsorption, causing systemic hypertension and glomerular hyperfiltration via tubuloglomerular feedback, and named this as &apos;protein metabolic overload hypothesis&apos;. Impaired metabolism of bioactive proteins such as angiotensin 11 and insulin in PTC may enhance hypertrophy of PTC and/or Na(+) reabsorption. Sleep apnoea syndrome, a frequent complication of diabetes and metabolic syndrome, may cause renal hypoxia and result in relative overload of protein metabolism in the kidneys. The development of strategies to identify patients with diabetes or metabolic syndrome who are at high risk for renal metabolic overload would allow intensive treatment of these patients in an effort to prevent the development of nephropathy. Further studies on the intracellular molecular signalling associated with megalin-mediated metabolic pathways may lead to the development of novel strategies for the treatment of nephropathies related to diabetes and metabolic syndrome.

DOI： 10.1111/j.1440-1797.2005.00453.x

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Liver-type fatty acid binding protein (L-FABP) binds with high affinity to hydrophobic molecules including free fatty acid, bile acid and bilirubin, which are potentially nephrotoxic, and is involved in their metabolism mainly in hepatocytes. L-FABP is released into the circulation, and patients with liver damage have an elevated plasma L-FABP level. L-FABP is also present in renal tubules; however, the precise localization of L-FABP and its potential role in the renal tubules are not known. In this study, we examined the cellular and subcellular localization of L-FABP in the rat kidney and tried to determine from where the L-FABP in kidney tissues had originated. Immunohistochemical studies of kidney sections localized L-FABP in the lysosomes of proximal tubule cells (PTC). In rats with carbon tetrachloride (CCl(4))-induced acute liver injury, we detected high levels of L-FABP in the circulation and in the kidney compared with those in the control rat by immunoblotting, while reverse transcription-polymerase chain reaction showed that the level of L-FABP mRNA expression in the kidney of CCl(4)-treated rats was low and did not differ from that in the control rat. When (35)S-L-FABP was intravenously administered to rats, the kidneys took up (35)S-L-FABP more preferentially than the liver and heart, and histoautoradiography of kidney sections revealed that (35)S-L-FABP was internalized via the apical domains of PTC. Quartz-crystal microbalance analysis revealed that L-FABP bound to megalin, a multiligand endocytotic receptor on PTC, in a Ca(2+)-dependent manner. Degradation assays using megalin-expressing rat yolk sac tumor-derived L2 cells demonstrated that megalin mediated the cellular uptake and catabolism of (125)I-L-FABP. In conclusion, circulatory L-FABP was found to be filtered by glomeruli and internalized by PTC probably via megalin-mediated endocytosis. These results suggest a novel renal uptake pathway for L-FABP, a carrier of hydrophobic molecules, some of which may exert nephrotoxic effects.

DOI： 10.1038/labinvest.3700240

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NEW YORK ACAD SCIENCES  

Advanced glycation end products (AGEs) are formed by the nonenzymatic Maillard reaction between sugars and proteins. Low-molecular weight AGES are filtered by renal glomeruli and then reabsorbed and metabolized by proximal tubule cells (PTCs). High-molecular weight AGES are also delivered to PTCs in proteinuric states. In patients with diabetes, AGE generation is increased, and the actions of AGES on PTCs are likely involved in the pathogenesis of diabetic nephropathy. In patients with chronic renal failure (CRF), reduced renal metabolism of AGEs likely accounts for the accumulation of AGEs in serum, leading to uremic complications including dialysis-related amyloidosis. AGE precursors such as reactive carbonyl compounds also accumulate in the sera of patients with CRF. It is likely that PTCs take up AGEs and AGE precursors via specific endocytotic receptors or transporters. Megalin is a multiligand endocytotic receptor that is abundantly expressed on PTCs. There is evidence that megalin is involved in the cellular uptake and degradation of AGES. We previously reported a cell therapy model involving implantation of megalin-expressing cells into experimental mice with renal failure for elimination of uremic toxin proteins. Further studies are needed to clarify the molecular mechanisms of the metabolism of AGEs and their precursors to develop a strategy

DOI： 10.1196/annals.1333.072

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Language：Japanese   Publisher：(公社)日本栄養・食糧学会  

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Language：Japanese   Publisher：(一社)日本病態栄養学会  

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DOI： 10.19020/KB.0000000098

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Language：Japanese   Publisher：(一社)日本神経学会  

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Language：Japanese   Publisher：(一社)日本腎臓学会  

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Language：Japanese   Publisher：(一社)日本病態栄養学会  

SGLT2阻害薬は近位尿細管における糖の再吸収を抑制することで尿糖排泄を増加し血糖低下をもたらす糖尿病治療薬であり、食事療法が密接にその治療効果へ影響を及ぼすことが予想される。症例は40歳女性。SGLT2阻害薬のイプラグリフロジンを開始と同時に、1400kcal/日にて栄養指導を月1回、継続的に行った。連日の食事記録より、2000kcal/日以上であった摂取エネルギーは平均1700kcal/日程度に減少した。35週間で体重は97.6kgから83.4kgと減少、HbA1cは7.4%から6.0%と改善した。SGLT2阻害薬開始後にエネルギー摂取量が増加する可能性が示唆されている。本症例は指導量よりは過剰であったものの、SGLT2阻害薬開始後に減少を認めており、体重減少および血糖改善につながったと考えられる。SGLT2阻害薬を使用中の患者においては正確な食事内容の把握と継続的な栄養指導が重要である。(著者抄録)

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Language：Japanese   Publisher：科学評論社  

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Language：Japanese   Publisher：(株)東京医学社  

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Language：Japanese   Publisher：(株)中外医学社  

タンパク質代謝は腎に負荷を与え,腎機能障害を増悪させると考えられてきた.タンパク質摂取制限が腎機能の低下速度を抑制するとする確証が十分に得られていないが,近年タンパク質摂取制限の有効性を示す報告がなされてきている.また,摂取タンパク質の種類が腎に与える影響についても検討が進んでいる.健常人では,糸球体を濾過する低分子量タンパク質が近位尿細管細胞によって再吸収・代謝されている.糸球体傷害をきたすと,本来糸球体を濾過しない物質やタンパク質の濾過が亢進し,その代謝負荷が近位尿細管の傷害を引き起こす可能性が考えられる.メガリンは近位尿細管におけるタンパク質代謝機構において重要な役割を担っている.Nrf2活性化薬バルドキソロンメチルは,2型糖尿病の糖尿病性腎症患者のeGFRを改善し,またサルにおいて,メガリンの発現低下とともにクレアチニンクリアランスの増大を認めることが報告されている.(著者抄録)

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DOI： 10.11477/mf.1542102512

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Language：Japanese   Publisher：Japanese Proteomics Society (Japan Human Proteome Organisation)  

DOI： 10.14889/jhupo.2011.0.186.0

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Language：Japanese   Publisher：新潟医学会  

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Language：Japanese   Publisher：(一社)日本腎臓学会  

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Language：Japanese   Publisher：(一社)日本糖尿病学会  

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Language：English   Presentation type：Poster presentation  

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