37
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Rapamycin Ameliorates Kidney Fibrosis by Inhibiting the Activation of mTOR Signaling in Interstitial Macrophages and Myofibroblasts

      research-article

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Interstitial fibrosis is an inevitable outcome of all kinds of progressive chronic kidney disease (CKD). Emerging data indicate that rapamycin can ameliorate kidney fibrosis by reducing the interstitial infiltrates and accumulation of extra cellular matrix (ECM). However, the cellular mechanism that regulates those changes has not been well understood yet. In this study, we revealed the persistent activation of mammalian target of rapamycin (mTOR) signaling in the interstitial macrophages and myofibroblasts, but rarely in injured proximal epithelial cells, CD4+ T cells, neutrophils, or endothelial cells, during the development of kidney fibrosis. Administration of rapamycin to unilateral ureteral obstruction (UUO) mice significantly suppressed the immunoreactivity of mTOR signaling, which decreased the inflammatory responses and ECM accumulation in the obstructed kidneys. Isolated macrophages from rapamycin-treated obstructed kidneys presented less inflammatory activity than vehicle groups. In vitro study confirmed that rapamycin significantly inhibited the fibrogenic activation of cultured fibroblasts (NIH3T3 cells), which was induced by the stimulation of TGF-β 1. Further experiment revealed that rapamycin did not directly inhibit the fibrogenesis of HK2 cells with aristolochic acid treatment. Our findings clarified that rapamycin can ameliorate kidney fibrosis by blocking the mTOR signaling in interstitial macrophages and myofibroblasts.

          Related collections

          Most cited references34

          • Record: found
          • Abstract: found
          • Article: not found

          Kidney injury molecule-1 (KIM-1), a putative epithelial cell adhesion molecule containing a novel immunoglobulin domain, is up-regulated in renal cells after injury.

          We report the identification of rat and human cDNAs for a type 1 membrane protein that contains a novel six-cysteine immunoglobulin-like domain and a mucin domain; it is named kidney injury molecule-1 (KIM-1). Structurally, KIM-1 is a member of the immunoglobulin gene superfamily most reminiscent of mucosal addressin cell adhesion molecule 1 (MAdCAM-1). Human KIM-1 exhibits homology to a monkey gene, hepatitis A virus cell receptor 1 (HAVcr-1), which was identified recently as a receptor for the hepatitis A virus. KIM-1 mRNA and protein are expressed at a low level in normal kidney but are increased dramatically in postischemic kidney. In situ hybridization and immunohistochemistry revealed that KIM-1 is expressed in proliferating bromodeoxyuridine-positive and dedifferentiated vimentin-positive epithelial cells in regenerating proximal tubules. Structure and expression data suggest that KIM-1 is an epithelial cell adhesion molecule up-regulated in the cells, which are dedifferentiated and undergoing replication. KIM-1 may play an important role in the restoration of the morphological integrity and function to postischemic kidney.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            The mTOR pathway is regulated by polycystin-1, and its inhibition reverses renal cystogenesis in polycystic kidney disease.

            Autosomal-dominant polycystic kidney disease (ADPKD) is a common genetic disorder that frequently leads to renal failure. Mutations in polycystin-1 (PC1) underlie most cases of ADPKD, but the function of PC1 has remained poorly understood. No preventive treatment for this disease is available. Here, we show that the cytoplasmic tail of PC1 interacts with tuberin, and the mTOR pathway is inappropriately activated in cyst-lining epithelial cells in human ADPKD patients and mouse models. Rapamycin, an inhibitor of mTOR, is highly effective in reducing renal cystogenesis in two independent mouse models of PKD. Treatment of human ADPKD transplant-recipient patients with rapamycin results in a significant reduction in native polycystic kidney size. These results indicate that PC1 has an important function in the regulation of the mTOR pathway and that this pathway provides a target for medical therapy of ADPKD.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Kidney injury molecule-1 is a phosphatidylserine receptor that confers a phagocytic phenotype on epithelial cells.

              Following injury, the clearance of apoptotic and necrotic cells is necessary for mitigation and resolution of inflammation and tissue repair. In addition to macrophages, which are traditionally assigned to this task, neighboring epithelial cells in the affected tissue are postulated to contribute to this process. Kidney injury molecule-1 (KIM-1 or TIM-1) is an immunoglobulin superfamily cell-surface protein not expressed by cells of the myeloid lineage but highly upregulated on the surface of injured kidney epithelial cells. Here we demonstrate that injured kidney epithelial cells assumed attributes of endogenous phagocytes. Confocal images confirm internalization of apoptotic bodies within KIM-1-expressing epithelial cells after injury in rat kidney tubules in vivo. KIM-1 was directly responsible for phagocytosis in cultured primary rat tubule epithelial cells and also porcine and canine epithelial cell lines. KIM-1 was able to specifically recognize apoptotic cell surface-specific epitopes phosphatidylserine, and oxidized lipoproteins, expressed by apoptotic tubular epithelial cells. Thus, KIM-1 is the first nonmyeloid phosphatidylserine receptor identified to our knowledge that transforms epithelial cells into semiprofessional phagocytes.
                Bookmark

                Author and article information

                Contributors
                Role: Editor
                Journal
                PLoS One
                PLoS ONE
                plos
                plosone
                PLoS ONE
                Public Library of Science (San Francisco, USA )
                1932-6203
                2012
                28 March 2012
                : 7
                : 3
                : e33626
                Affiliations
                [1 ]Department of Nephrology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
                [2 ]Kidney Research Institute of Central South University, Changsha, Hunan, P.R. China
                [3 ]Department of Ophthalmology, the Second Xiangya Hospital, Central South University, Changsha, Hunan, P.R. China
                French National Centre for Scientific Research, France
                Author notes

                Conceived and designed the experiments: GC FL. Performed the experiments: GC HC CW. Analyzed the data: GC HC YP LS. Contributed reagents/materials/analysis tools: HL. Wrote the paper: GC. Revised the manuscript: FL.

                Article
                PONE-D-11-21927
                10.1371/journal.pone.0033626
                3314672
                22470459
                843595f8-7edf-4f1f-b8b5-e75431e96178
                Chen et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
                History
                : 4 November 2011
                : 14 February 2012
                Page count
                Pages: 14
                Categories
                Research Article
                Biology
                Immunology
                Immunity
                Model Organisms
                Animal Models
                Molecular Cell Biology
                Signal Transduction
                Signaling in Selected Disciplines
                Medicine
                Nephrology

                Uncategorized
                Uncategorized

                Comments

                Comment on this article