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      Differential Nephron HO-1 Expression following Glomerular Epithelial Cell Injury

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          Abstract

          Background: In proteinuria of glomerular origin there is upregulation of heme-oxygenase (HO), the rate-limiting enzyme of heme degradation, in the nephron in a segment-specific manner. To better characterize this phenomenon, we employed a model of proteinuria resulting from disruption of the glomerular capillary permeability barrier to protein by administration of the glomerular epithelial cell toxin puromycin aminonucleoside (PAN) to rats. In this model, we assessed nephron distribution of the expression of the inducible HO isoform, HO-1, and the role of free radicals in modulating HO-1 expression. Methods: Rats were injected with either vehicle (dimethyl sulfoxide) or PAN or the spin trap free radical stabilizer α-phenyl-N- tert butyl nitrone (PBN), or with both PAN and PBN. Ten days following the PAN injection, urine protein, creatinine, nitric oxide (NO) and malonyldialdehyde (MDA) were measured. Kidney sections and protein lysates were assessed for changes in HO-1 expression by immunohistochemistry and Western blot analysis. Results: In control animals (DMSO or PBN alone) there was no proteinuria and very weak or absent HO-1 staining in nephron segments. PAN treatment induced proteinuria and increased urine MDA excretion. In these animals, there was a robust HO-1 expression mainly in tubules and in glomerular parietal but not visceral epithelial cells. Unilateral ureteral obstruction to interrupt glomerular filtration in animals treated with PAN abrogated tubular HO-1 expression in the kidney ipsilateral to the obstruction. Administration of PBN to PAN-treated animals reduced proteinuria and MDA excretion while it markedly augmented tubular HO-1 expression. This augmentation was prominent in tubular cells of the inner cortex/outer medulla. Conclusions: These observations indicate that upregulation of nephron HO-1 following disruption of the glomerular permeability barrier occurs at sites downstream of this barrier and is mediated by a filtered HO-1 inducer(s). Scavenging of free radicals potentiates the effect of this inducer and unmasks nephron segments most and least capable of upregulating HO-1.

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          Most cited references 12

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          Heme oxygenase-1 mediates the anti-inflammatory effect of interleukin-10 in mice.

          The mechanisms underlying the action of the potent anti-inflammatory interleukin-10 (IL-10) are poorly understood. Here we show that, in murine macrophages, IL-10 induces expression of heme oxygenase-1 (HO-1), a stress-inducible protein with potential anti-inflammatory effect, via a p38 mitogen-activated protein kinase-dependent pathway. Inhibition of HO-1 protein synthesis or activity significantly reversed the inhibitory effect of IL-10 on production of tumor necrosis factor-alpha induced by lipopolysaccharide (LPS). Additional experiments revealed the involvement of carbon monoxide, one of the products of HO-1-mediated heme degradation, in the anti-inflammatory effect of IL-10 in vitro. Induction of HO-1 by IL-10 was also evident in vivo. IL-10-mediated protection against LPS-induced septic shock in mice was significantly attenuated by cotreatment with the HO inhibitor, zinc protoporphyrin. The identification of HO-1 as a downstream effector of IL-10 provides new possibilities for improved therapeutic approaches for treating inflammatory diseases.
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            Heme oxygenase: protective gene or Trojan horse.

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              Role of heme oxygenase-1 in the regulation of manganese superoxide dismutase gene expression in oxidatively-challenged astroglia.

              Manganese superoxide dismutase (MnSOD) is an antioxidant enzyme that reduces superoxide anion to hydrogen peroxide in cell mitochondria. MnSOD is overexpressed in normal aging brain and in various central nervous system disorders; however, the mechanisms mediating the upregulation of MnSOD under these conditions remain poorly understood. We previously reported that cysteamine (CSH) and other pro-oxidants rapidly induce the heme oxygenase-1 (HO-1) gene in cultured rat astroglia followed by late upregulation of MnSOD in these cells. In the present study, we demonstrate that antecedent upregulation of HO-1 is necessary and sufficient for subsequent induction of the MnSOD gene in neonatal rat astroglia challenged with CSH or dopamine, and in astroglial cultures transiently transfected with full-length human HO-1 cDNA. Treatment with potent antioxidants attenuates MnSOD expression in HO-1-transfected astroglia, strongly suggesting that intracellular oxidative stress signals MnSOD gene induction in these cells. Activation of this HO-1-MnSOD axis may play an important role in the pathogenesis of Alzheimer disease, Parkinson disease and other free radical-related neurodegenerative disorders. In these conditions, compensatory upregulation of MnSOD may protect mitochondria from oxidative damage accruing from heme-derived free iron and carbon monoxide liberated by the activity of HO-1. Copyright 2000 Wiley-Liss, Inc.
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                Author and article information

                Journal
                NEE
                Nephron Exp Nephrol
                10.1159/issn.1660-2129
                Cardiorenal Medicine
                S. Karger AG
                1660-2129
                2006
                July 2006
                07 April 2006
                : 103
                : 4
                : e131-e138
                Affiliations
                aLaboratory of AIDS Pathogenesis and Molecular Therapeutics, Center for Neurovirology, Temple University, Philadelphia, Pa.; bNephrology Division, Medical College of Wisconsin, Milwaukee, Wisc., and cNephrology Division, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, N.J., USA
                Article
                92544 Nephron Exp Nephrol 2006;103:e131–e138
                10.1159/000092544
                16601358
                © 2006 S. Karger AG, Basel

                Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug. Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

                Page count
                Figures: 7, References: 20, Pages: 1
                Product
                Self URI (application/pdf): https://www.karger.com/Article/Pdf/92544
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