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Henrik Birn - One of the best experts on this subject based on the ideXlab platform.

  • Renal miR-148b is associated with Megalin down-regulation in IgA nephropathy
    Bioscience Reports, 2018
    Co-Authors: Zhanzheng Zhao, Jing Xiao, Zheng Wang, Xiangfei He, Henrik Birn
    Abstract:

    Megalin is essential for proximal tubule reabsorption of filtered proteins, hormones, and vitamins, and its dysfunction has been reported in IgA nephropathy (IgAN). miR-148b has been shown to regulate renal Megalin expression in vitro and in animal models of kidney disease. We examined a potential role of miR-148b and other miRNAs in regulating Megalin expression in IgAN by analyzing the association between Megalin and miR-148b, miR-21, miR-146a, and miR-192 expression. Quantitative PCR (qPCR) analysis identified a marked increase in renal levels of several miRNAs, including miR-148b, miR-21, miR-146a, and a significant decrease in Megalin mRNA levels in IgAN patients when compared with normal controls. By multiple linear regression analysis, however, only renal miR-148b was independently associated with Megalin mRNA levels in IgAN. Proximal tubule Megalin expression was further evaluated by immunofluorescence labeling of biopsies from the patients. The Megalin expression was significantly lower in patients with highest levels of renal miR-148b compared with patients with lowest levels. To examine the direct effects of the miRNAs on Megalin and other membrane proteins expression, proximal tubule LLC-PK1 cells were transfected with miR-148b, miR-21, miR-146a, or miR-192 mimics. Transfection with miR-148b mimic, but not the other three miRNA mimics inhibited endogenous Megalin mRNA expression. No significant effect of any of the four miRNA mimics was observed on cubilin or aquaporin 1 (AQP1) mRNA expression. The findings suggest that miR-148b negatively regulates Megalin expression in IgAN, which may affect renal uptake and metabolism of essential substances.

  • Megalin dependent urinary cystatin c excretion in ischemic kidney injury in rats
    PLOS ONE, 2017
    Co-Authors: Erik Ilsø Christensen, Henrik Birn, Rikke Nielsen, Danny Jensen, Casper Kierulflassen, Marie Louise Vindvad Kristensen, Rikke Norregaard, Kathrin Weyer
    Abstract:

    Background Cystatin C, a marker of kidney injury, is freely filtered in the glomeruli and reabsorbed by the proximal tubules. Megalin and cubilin are endocytic receptors essential for reabsorption of most filtered proteins. This study examines the role of these receptors for the uptake and excretion of cystatin C and explores the effect of renal ischemia/reperfusion injury on renal cystatin C uptake and excretion in a rat model. Methods Binding of cystatin C to Megalin and cubilin was analyzed by surface plasmon resonance analysis. ELISA and/or immunoblotting and immunohistochemistry were used to study the urinary excretion and tubular uptake of endogenous cystatin C in mice. Furthermore, renal uptake and urinary excretion of cystatin C was investigated in rats exposed to ischemia/reperfusion injury. Results A high affinity binding of cystatin C to Megalin and cubilin was identified. Megalin deficient mice revealed an increased urinary excretion of cystatin C associated with defective uptake by endocytosis. In rats exposed to ischemia/reperfusion injury urinary cystatin C excretion was increased and associated with a focal decrease in proximal tubule endocytosis with no apparent change in Megalin expression. Conclusions Megalin is essential for the normal tubular recovery of endogenous cystatin C. The increase in urinary cystatin C excretion after ischemia/reperfusion injury is associated with decreased tubular uptake but not with reduced Megalin expression.

  • Megalin in acute kidney injury foe and friend
    American Journal of Physiology-renal Physiology, 2014
    Co-Authors: Ravikiran Mahadevappa, Erik Ilsø Christensen, Henrik Birn, Rikke Nielsen
    Abstract:

    The kidney proximal tubule is a key target in many forms of acute kidney injury (AKI). The multiligand receptor Megalin is responsible for the normal proximal tubule uptake of filtered molecules, including nephrotoxins, cytokines, and markers of AKI. By mediating the uptake of nephrotoxins, Megalin plays an essential role in the development of some types of AKI. However, Megalin also mediates the tubular uptake of molecules implicated in the protection against AKI, and changes in Megalin expression have been demonstrated in AKI in animal models. Thus, modulation of Megalin expression in response to AKI may be an important part of the tubule cell adaption to cellular protection and regeneration and should be further investigated as a potential target of intervention. This review explores current evidence linking Megalin expression and function to the development, diagnosis, and progression of AKI as well as renal protection against AKI.

  • renal phenotypic investigations of Megalin deficient patients novel insights into tubular proteinuria and albumin filtration
    Nephrology Dialysis Transplantation, 2013
    Co-Authors: Tina Storm, Henrik Birn, P Verroust, Lisbeth Tranebjaerg, Carina Frykholm, Tryggve Neveus, Birgitta Sundelin, Jens Michael Hertz, Gerd Holmstrom, Katharina Ericson
    Abstract:

    BackgroundThe reabsorption of filtered plasma proteins, hormones and vitamins by the renal proximal tubules is vital for body homeostasis. Studies of Megalin-deficient mice suggest that the large multi-ligand endocytic receptor Megalin plays an essential role in this process. In humans, dysfunctional Megalin causes the extremely rare Donnai-Barrow/Facio-Oculo-Acustico-Renal (DB/FOAR) syndrome characterized by a characteristic and multifaceted phenotype including low-molecular-weight proteinuria. In this study, we examined the role of Megalin for tubular protein reabsorption in humans through analysis of proximal tubular function in Megalin-deficient patients.MethodsDirect sequencing of the Megalin-encoding gene (LRP2) was performed in a family in which three children presented with classical DB/FOAR manifestations. Renal consequences of Megalin deficiency were investigated through immunohistochemical analyses of renal biopsy material and immunoblotting of urine samples.ResultsIn the patients, a characteristic urinary protein profile with increased urinary excretion of vitamin D-binding protein, retinol-binding protein and albumin was associated with absence of, or reduced, proximal tubular endocytic uptake as shown by renal immunohistochemistry. In the absence of tubular uptake, urinary albumin excretion was in the micro-albuminuric range suggesting that limited amounts of albumin are filtered in human glomeruli.ConclusionsThis study demonstrated that Megalin plays an essential role for human proximal tubular protein reabsorption and suggests that only limited amounts of albumin is normally filtered in the human glomeruli. Finally, we propose that the characteristic urinary protein profile of DB/FOAR patients may be utilized as a diagnostic marker of Megalin dysfunction.

  • Megalin and cubilin synergistic endocytic receptors in renal proximal tubule
    American Journal of Physiology-renal Physiology, 2001
    Co-Authors: Erik Ilsø Christensen, Henrik Birn
    Abstract:

    The multiligand, endocytic receptors Megalin and cubilin are colocalized in the renal proximal tubule. They are heavily expressed in the apical endocytic apparatus. Megalin is a 600-kDa transmembra...

Erik Ilsø Christensen - One of the best experts on this subject based on the ideXlab platform.

  • selective ablation of Megalin in the retinal pigment epithelium results in megaophthalmos macromelanosome formation and severe retina degeneration
    Investigative Ophthalmology & Visual Science, 2019
    Co-Authors: Tina Storm, Erik Ilsø Christensen, Thomas Burgoyne, Joshua L Dunaief, Clare E Futter, Rikke Nielsen
    Abstract:

    PURPOSE: Mutations in the Megalin-encoding gene, LRP2, cause high myopia as seen in patients suffering from Donnai-Barrow/facio-oculo-acoustico-renal syndrome. Megalin is present in both the nonpigmented epithelium of the ciliary body and in the RPE. In this study, we set out to establish an animal model to study the mechanisms underlying the ocular phenotype and to establish if high myopia/megaophthalmos is induced by postnatal Megalin-deficiency in the RPE. METHODS: Postnatal RPE-specific deletion of Megalin was generated by crossing mice bearing a homozygous loxP-flanked Lrp2 allele with transgenic mice expressing the Cre recombinase driven by the BEST1 promotor. The model was investigated by immunohistologic techniques, and transmission electron microscopy. RESULTS: Mice with postnatal RPE-specific loss of Megalin developed a megaophthalmos phenotype with dramatic increase in ocular size and severe retinal thinning associated with compromised vision. This phenotype was present at postnatal day 14, indicating rapid development in the period from onset of BEST1 promotor activity at postnatal day 10. Additionally, RPE melanosomes exhibited abnormal size and morphology, suggested by electron tomography to be caused by fusion events between multiple melanosomes. CONCLUSIONS: Postnatal loss of Megalin in the RPE induces dramatic and rapid ocular growth and retinal degeneration compatible with the high myopia observed in Donnai-Barrow patients. The morphologic changes of RPE melanosomes, believed to be largely inert and fully differentiated at birth, suggested a continued plasticity of mature melanosomes and a requirement for Megalin to maintain their number and morphology.

  • Megalin dependent urinary cystatin c excretion in ischemic kidney injury in rats
    PLOS ONE, 2017
    Co-Authors: Erik Ilsø Christensen, Henrik Birn, Rikke Nielsen, Danny Jensen, Casper Kierulflassen, Marie Louise Vindvad Kristensen, Rikke Norregaard, Kathrin Weyer
    Abstract:

    Background Cystatin C, a marker of kidney injury, is freely filtered in the glomeruli and reabsorbed by the proximal tubules. Megalin and cubilin are endocytic receptors essential for reabsorption of most filtered proteins. This study examines the role of these receptors for the uptake and excretion of cystatin C and explores the effect of renal ischemia/reperfusion injury on renal cystatin C uptake and excretion in a rat model. Methods Binding of cystatin C to Megalin and cubilin was analyzed by surface plasmon resonance analysis. ELISA and/or immunoblotting and immunohistochemistry were used to study the urinary excretion and tubular uptake of endogenous cystatin C in mice. Furthermore, renal uptake and urinary excretion of cystatin C was investigated in rats exposed to ischemia/reperfusion injury. Results A high affinity binding of cystatin C to Megalin and cubilin was identified. Megalin deficient mice revealed an increased urinary excretion of cystatin C associated with defective uptake by endocytosis. In rats exposed to ischemia/reperfusion injury urinary cystatin C excretion was increased and associated with a focal decrease in proximal tubule endocytosis with no apparent change in Megalin expression. Conclusions Megalin is essential for the normal tubular recovery of endogenous cystatin C. The increase in urinary cystatin C excretion after ischemia/reperfusion injury is associated with decreased tubular uptake but not with reduced Megalin expression.

  • Megalin Is Predominantly Observed in Vesicular Structures in First and Third Trimester Cytotrophoblasts of the Human Placenta
    Journal of Histochemistry and Cytochemistry, 2016
    Co-Authors: Erik Ilsø Christensen, Julie Nelly Christensen, T Kjaergaard, Niels Uldbjerg, Agnete Larsen, Bent Honoré, Mette Madsen
    Abstract:

    The membrane receptor Megalin is crucial for normal fetal development. Besides its expression in the developing fetus, Megalin is also expressed in the human placenta. Similar to its established function in the kidney proximal tubules, placental Megalin has been proposed to mediate uptake of vital nutrients. However, details of Megalin expression, subcellular localization, and function in the human placenta remain to be established. By immunohistochemical analyses of first trimester and term human placenta, we showed that Megalin is predominantly expressed in cytotrophoblasts, the highly proliferative cells in placenta. Only limited amounts of Megalin could be detected in syncytiotrophoblasts and least in term placenta syncytiotrophoblasts. Immunocytochemical analyses furthermore showed that placental Megalin associates with structures of the endolysosomal apparatus. Combined, our results clearly place placental Megalin in the context of endocytosis and trafficking of ligands. However, due to the limited ...

  • Megalin in acute kidney injury foe and friend
    American Journal of Physiology-renal Physiology, 2014
    Co-Authors: Ravikiran Mahadevappa, Erik Ilsø Christensen, Henrik Birn, Rikke Nielsen
    Abstract:

    The kidney proximal tubule is a key target in many forms of acute kidney injury (AKI). The multiligand receptor Megalin is responsible for the normal proximal tubule uptake of filtered molecules, including nephrotoxins, cytokines, and markers of AKI. By mediating the uptake of nephrotoxins, Megalin plays an essential role in the development of some types of AKI. However, Megalin also mediates the tubular uptake of molecules implicated in the protection against AKI, and changes in Megalin expression have been demonstrated in AKI in animal models. Thus, modulation of Megalin expression in response to AKI may be an important part of the tubule cell adaption to cellular protection and regeneration and should be further investigated as a potential target of intervention. This review explores current evidence linking Megalin expression and function to the development, diagnosis, and progression of AKI as well as renal protection against AKI.

  • Megalin deficiency offers protection from renal aminoglycoside accumulation
    Journal of Biological Chemistry, 2002
    Co-Authors: Christian Schmitz, Erik Ilsø Christensen, Jan Hilpert, Christian Jacobsen, Friedrich C Luft, Christian Boensch, Thomas E Willnow
    Abstract:

    Aminoglycosides are antibiotics commonly used to treat life-threatening Gram-negative bacterial infections. However, their use is hampered by their severe nephrotoxicity due to accumulation in renal proximal tubules. Several pathways have been implicated in the renal uptake of aminoglycosides including Megalin, an endocytic receptor in proximal tubular cells. Here, we have used mouse models with genetic or functional Megalin deficiency to explore the contribution of Megalin and other pathways to renal aminoglycoside uptake in vivo. We demonstrate that the uptake of aminoglycosides into the kidney directly correlates with renal Megalin activity and is completely eliminated in mice lacking the receptor. Thus, our studies provide unequivocal evidence that Megalin is the only major pathway responsible for renal aminoglycoside accumulation and that the receptor represents a unique drug target to prevent aminoglycoside-induced nephrotoxicity in patients.

Thomas E Willnow - One of the best experts on this subject based on the ideXlab platform.

  • Megalin contributes to the early injury of proximal tubule cells during nonselective proteinuria
    Kidney International, 2008
    Co-Authors: Akihiko Saito, Thomas E Willnow, Yaeko Motoyoshi, Taiji Matsusaka, Ira Pastan, Shuki Mizutani, Iekuni Ichikawa
    Abstract:

    Megalin, a member of the LDL receptor family, is expressed on the apical membrane of proximal tubules and serves as an endocytic scavenger of filtered proteins and hence might contribute to the tubule injury as a consequence of glomerular disease. To study its role, we crossed Megalin knockout mosaic mice (lacking Megalin expression in 60% of proximal tubule cells) with NEP25 mice (a transgenic line expressing human CD25 in the podocyte). Treatment of this transgenic mouse with the immunotoxin causes nephrotic syndrome, focal segmental glomerulosclerosis and tubule-interstitial injury. Following this treatment, the double transgenic mice had massive non-selective proteinuria and mild glomerular and tubular injury. Comparison of Megalin-containing to Megalin-deficient proximal tubule cells within each kidney showed that albumin, immunoglobulin light chain, IgA and IgG were preferentially accumulated in proximal tubule cells expressing Megalin. Tubule injury markers such as heme-oxygenase-1, monocyte chemoattractant protein-1 and cellular apoptosis were also preferentially found in these Megalin-expressing cells. These results show that Megalin plays a pivotal role in the reabsorption of small to large molecular size proteins and provides direct in vivo evidence that reabsorption of filtered proteins triggers events leading to tubule injury.

  • abrogation of protein uptake through Megalin deficient proximal tubules does not safeguard against tubulointerstitial injury
    Journal of The American Society of Nephrology, 2007
    Co-Authors: Franziska Theilig, Wilhelm Kriz, Timo Jerichow, Petra Schrade, Brunhilde Hahnel, Thomas E Willnow, S Bachmann
    Abstract:

    Sustained proteinuria and tubulointerstitial damage have been closely linked with progressive renal failure. Upon excess protein endocytosis, tubular epithelial cells are thought to produce mediators that promote inflammation, tubular degeneration, and fibrosis. This concept was tested in a transgenic mouse model with Megalin deficiency. Application of an anti-glomerular basement membrane serum to transgenic Megalin-deficient mice [Cre(+)/GN] and Megalin-positive littermates [Cre(-)/GN] produced the typical glomerulonephritis (GN) with heavy proteinuria in both groups. Tubulointerstitial damages correlated closely with glomerular damages in pooled Cre(+)/GN and Cre(-)/GN mice. Owing to a mosaic pattern of Megalin expression in the mutant mice, Cre(+)/GN kidneys permitted side-by-side analysis of Megalin-deficient and Megalin-positive tubules in the same kidney. Protein endocytosis was found only in Megalin-positive cells. TGF-beta, intercellular adhesion molecule, vascular cellular adhesion molecule, endothelin-1, and cell proliferation were high in Megalin-positive cells, whereas apoptosis, heat-shock protein 25, and osteopontin were enhanced in Megalin-deficient cells. No fibrotic changes were associated with either phenotype. Tubular degeneration with interstitial inflammation was found only in nephrons with extensive crescentic lesions at the glomerulotubular junction. In sum, enhanced protein endocytosis indeed led to an upregulation of profibrotic mediators in a Megalin-dependent way; however, there was no evidence that endocytosis played a pathogenetic role in the development of the tubulointerstitial disease.

  • elucidation of Megalin lrp2 dependent endocytic transport processes in the larval zebrafish pronephros
    Journal of Cell Science, 2006
    Co-Authors: Uwe Anzenberger, Thomas E Willnow, Nana Bitavragim, Stefan Rohr, Franziska Rudolph, Bastian Dehmel, Salim Abdelilahseyfried
    Abstract:

    Megalin/LRP2 is an endocytic receptor in the proximal tubules of the mammalian kidney that plays a central role in the clearance of metabolites from the glomerular filtrate. To establish a genetic model system for elucidation of molecular components of this retrieval pathway, we characterized orthologous transport processes in the zebrafish. We show that expression of Megalin/LRP2 and its co-receptor cubilin is conserved in the larval zebrafish pronephros and demarcates a segment of the pronephric duct that is active in clearance of tracer from the ultrafiltrate. Knock-down of Megalin/LRP2 causes lack of Rab4-positive endosomes in the proximal pronephric duct epithelium and abrogates apical endocytosis. Similarly, knock-down of the Megalin/LRP2 adaptor Disabled 2 also blocks renal clearance processes. These results demonstrate the conservation of the Megalin/LRP2 retrieval pathway between the larval zebrafish pronephros and the mammalian kidney and set the stage for dissection of the renal endocytic machinery in a simple model organism. Using this model system, we provide first genetic evidence that renal tubular endocytosis and formation of endosomes is a ligand-induced process that crucially depends on Megalin/LRP2 activity.

  • Megalin mediated reuptake of retinol in the kidneys of mice is essential for vitamin a homeostasis
    Journal of Nutrition, 2005
    Co-Authors: Jens Raila, Thomas E Willnow, Florian J Schweigert
    Abstract:

    The reuptake of retinol (ROH) and retinol-binding protein (RBP) in the kidneys is mediated by the endocytic receptor Megalin, suggesting an important role for this receptor in vitamin A (VA) metabolism. We examined the extent to which Megalin deficiency may affect urinary ROH excretion, levels of ROH and RBP in plasma, as well as storage of VA in liver and kidney. For this purpose, mice with a kidney-specific Megalin gene defect (Megalin l o x / l o x ; apoE C r e ) and control mice (Megalin l o x / l o x ) were fed either a basal diet containing 4500 retinol equivalents (RE)/kg diet or a diet without VA during experimental periods of 42 and 84 d. Urinary ROH excretion was observed only in Megalin l o x / l o x ; apoE C r e mice (P < 0.0001, 2-way ANOVA) and not in the controls. Plasma ROH and RBP differed only by diet (P < 0.05), but not genotype (P = 0.615). A major effect of Megalin deficiency, however, was evident in retinyl ester levels in the liver (P < 0.05), which were ∼37% lower than those in Megalin l o x / l o x controls (P < 0.05, Student's t test) during the 84-d period of dietary VA deprivation. Kidney levels of VA were not affected by the receptor gene defect. The findings demonstrate that urinary ROH excretion caused by Megalin deficiency requires accelerated mobilization of hepatic VA stores to maintain normal plasma ROH levels, which suggests that Megalin plays an essential role in systemic VA homeostasis.

  • Megalin is essential for renal proximal tubule reabsorption of 111 in dtpa octreotide
    The Journal of Nuclear Medicine, 2005
    Co-Authors: Marion De Jong, Thomas E Willnow, Raffaella Barone, Eric P Krenning, Bert F Bernard, Marleen Melis, Theo J Visser, Michael Gekle, Stephan Walrand, Francois Jamar
    Abstract:

    Radiolabeled somatostatin analogs have been shown to be important radiopharmaceuticals for tumor diagnosis and radionuclide therapy. The kidney has appeared to be the critical organ during radionuclide therapy because of peptide reabsorption and retention in the proximal tubules after glomerular filtration. The molecular mechanism of renal reabsorption of these analogs has not been clarified. A possible receptor candidate is Megalin, a multiligand scavenger receptor in the renal proximal tubules. The objective of this study was to investigate the role of Megalin in tubular reabsorption of radiolabeled somatostatin analogs by using kidney-specific Megalin-deficient mice versus mice with normal renal Megalin expression. [(111)In-Diethylenetriaminepentaacetic acid (DTPA)]octreotide was used as a practical model of peptide. METHODS: Renal uptake of [(111)In-DTPA]octreotide was determined by animal SPECT scintigraphy at different time points after injection of the tracer and by measurement of radioactivity after isolation of the organs. Furthermore, ex vivo autoradiography of renal sections revealed the zonal distribution of radioactivity in the Megalin-deficient and Megalin-expressing kidneys. RESULTS: SPECT scintigraphy of [(111)In-DTPA]octreotide at 3 and 24 h after injection clearly showed lower renal radioactivity in Megalin-deficient kidneys than in Megalin-expressing kidneys, both in male and in female mice, in accordance with counts obtained after isolation of the organ (70%-85% reduction of uptake in the Megalin-deficient kidneys, P < 0.001). Renal uptake of [(111)In-DTPA]octreotide was significantly higher in female than in male kidneys (P < 0.001). Ex vivo autoradiograms clearly showed that renal radioactivity was not homogeneously distributed in the Megalin-expressing kidneys but localized in the renal cortex. Quantification of the autoradiogram data confirmed the reduced radioactivity in the renal cortex of Megalin-deficient kidneys. CONCLUSION: This study revealed the molecular mechanism of [(111)In-DTPA]octreotide uptake in renal proximal tubules involving the receptor Megalin. Identification of Megalin may be crucial for further research into strategies to reduce renal uptake.

Ryohei Kaseda - One of the best experts on this subject based on the ideXlab platform.

  • Correlation of prechemotherapy urinary Megalin ectodomain (A-Megalin) levels with the development of cisplatin-induced nephrotoxicity: a prospective observational study.
    BMC Cancer, 2019
    Co-Authors: Satoshi Shoji, Michihiro Hosojima, Ryohei Kaseda, Hideyuki Kabasawa, Shoji Kuwahara, Nobumasa Aoki, Rie Kondo, Satoru Miura, Satoshi Watanabe, Naohito Tanabe
    Abstract:

    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. This prospective observational study involved 45 chemotherapy-naive 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. 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. 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.

  • Megalin blockade with cilastatin suppresses drug induced nephrotoxicity
    Journal of The American Society of Nephrology, 2017
    Co-Authors: Yoshihisa Hori, Michihiro Hosojima, Ryohei Kaseda, Hideyuki Kabasawa, Shankhajit De, Shoji Kuwahara, Tomomichi Iida, Sawako Goto, Nobumasa Aoki, Reika Kaneko
    Abstract:

    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.

  • exocytosis mediated urinary full length Megalin excretion is linked with the pathogenesis of diabetic nephropathy
    Diabetes, 2017
    Co-Authors: Shankhajit De, Michihiro Hosojima, Ryohei Kaseda, Hideyuki Kabasawa, Shoji Kuwahara, Tomomi Ishikawa, Piyali Sarkar, Yusuke Yoshioka, Tomomichi Iida, Sawako Goto
    Abstract:

    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.

  • significance of urinary full length and ectodomain forms of Megalin in patients with type 2 diabetes
    Diabetes Care, 2012
    Co-Authors: Shinya Ogasawara, Tetsuro Takeda, Noriaki Iino, Michihiro Hosojima, Ryohei Kaseda, Hideyuki Kabasawa, Keiko Yamamotokabasawa, Hiroyuki Kurosawa, Hiroyoshi Sato, Yoshiki Suzuki
    Abstract:

    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 NH(2) (amino [A]-Megalin assay) and COOH (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) (<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.

  • Significance of Urinary Full-Length and Ectodomain Forms of Megalin in Patients With Type 2 Diabetes
    Diabetes Care, 2012
    Co-Authors: Shinya Ogasawara, Tetsuro Takeda, Noriaki Iino, Michihiro Hosojima, Ryohei Kaseda, Hideyuki Kabasawa, Hiroyuki Kurosawa, Hiroyoshi Sato, Keiko Yamamoto-kabasawa, Yoshiki Suzuki
    Abstract:

    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 COOH (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) (

Michihiro Hosojima - One of the best experts on this subject based on the ideXlab platform.

  • Correlation of prechemotherapy urinary Megalin ectodomain (A-Megalin) levels with the development of cisplatin-induced nephrotoxicity: a prospective observational study.
    BMC Cancer, 2019
    Co-Authors: Satoshi Shoji, Michihiro Hosojima, Ryohei Kaseda, Hideyuki Kabasawa, Shoji Kuwahara, Nobumasa Aoki, Rie Kondo, Satoru Miura, Satoshi Watanabe, Naohito Tanabe
    Abstract:

    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. This prospective observational study involved 45 chemotherapy-naive 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. 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. 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.

  • Megalin blockade with cilastatin suppresses drug induced nephrotoxicity
    Journal of The American Society of Nephrology, 2017
    Co-Authors: Yoshihisa Hori, Michihiro Hosojima, Ryohei Kaseda, Hideyuki Kabasawa, Shankhajit De, Shoji Kuwahara, Tomomichi Iida, Sawako Goto, Nobumasa Aoki, Reika Kaneko
    Abstract:

    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.

  • exocytosis mediated urinary full length Megalin excretion is linked with the pathogenesis of diabetic nephropathy
    Diabetes, 2017
    Co-Authors: Shankhajit De, Michihiro Hosojima, Ryohei Kaseda, Hideyuki Kabasawa, Shoji Kuwahara, Tomomi Ishikawa, Piyali Sarkar, Yusuke Yoshioka, Tomomichi Iida, Sawako Goto
    Abstract:

    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.

  • significance of urinary full length and ectodomain forms of Megalin in patients with type 2 diabetes
    Diabetes Care, 2012
    Co-Authors: Shinya Ogasawara, Tetsuro Takeda, Noriaki Iino, Michihiro Hosojima, Ryohei Kaseda, Hideyuki Kabasawa, Keiko Yamamotokabasawa, Hiroyuki Kurosawa, Hiroyoshi Sato, Yoshiki Suzuki
    Abstract:

    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 NH(2) (amino [A]-Megalin assay) and COOH (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) (<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.

  • Significance of Urinary Full-Length and Ectodomain Forms of Megalin in Patients With Type 2 Diabetes
    Diabetes Care, 2012
    Co-Authors: Shinya Ogasawara, Tetsuro Takeda, Noriaki Iino, Michihiro Hosojima, Ryohei Kaseda, Hideyuki Kabasawa, Hiroyuki Kurosawa, Hiroyoshi Sato, Keiko Yamamoto-kabasawa, Yoshiki Suzuki
    Abstract:

    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 COOH (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) (