Identification and Characterization of New Proteins in Podocyte Dysfunction of Membranous Nephropathy by Proteomic Analysis of Renal Biopsy (original) (raw)
Related papers
Journal of Proteome Research, 2006
Membranous nephropathy is one of the most common causes of primary glomerular diseases worldwide. The present study adopted a gel-based proteomics approach to better understand the pathophysiology and define biomarker candidates of human membranous nephropathy using an animal model of passive Heymann nephritis (PHN). Clinical characteristics of Sprague-Dawley rats injected with rabbit anti-Fx1A antiserum mimicked those of human membranous nephropathy. Serial urine samples were collected at Days 0, 10, 20, 30, 40, and 50 after the injection with anti-Fx1A (number of rats ) 6; total number of gels ) 36). Urinary proteome profiles were examined using 2D-PAGE and SYPRO Ruby staining. Quantitative intensity analysis and ANOVA with Tukey post-hoc multiple comparisons revealed 37 differentially expressed proteins among 6 different time-points. These altered proteins were successfully identified by MALDI-TOF MS and classified into 6 categories: (i) proteins with decreased urinary excretion during PHN; (ii) proteins with increased urinary excretion during PHN; (iii) proteins with increased urinary excretion during PHN, but which finally returned to basal levels; (iv) proteins with increased urinary excretion during PHN, but which finally declined below basal levels;
Antigen Identification in Membranous Nephropathy Moves toward Targeted Monitoring and New Therapy
Journal of the American Society of Nephrology, 2010
Membranous nephropathy, a disease characterized by an accumulation of immune deposits on the outer aspect of the glomerular basement membrane, is the most common cause of idiopathic nephrotic syndrome in Caucasian adults. In the rat model described by Heymann in 1959, the target antigen of antibodies is megalin, a multiligand receptor expressed in the rat glomerulus but absent from the human glomerulus. In the past few years, two major antigens have been identified in human membranous nephropathy. The first is neutral endopeptidase, the alloantigen involved in neonatal cases of membranous nephropathy that occur in newborns from neutral endopeptidase-deficient mothers. The second is the type-M phospholipase A2 receptor (PLA 2 R), the first autoantigen identified in idiopathic membranous nephropathy in the adult. Megalin, neutral endopeptidase, and PLA 2 R are all expressed on the podocyte surface where they serve as targets for circulating antibodies, which lead to in situ immune complex formation, complement activation, and proteinuria. The recent discovery of neutral endopeptidase and PLA 2 R provides new tools for monitoring human disease activity and should be of value in designing new antigen-driven therapeutic strategies.
International Journal of Molecular Sciences
Primary focal segmental glomerulosclerosis (FSGS), along with minimal change disease (MCD), are diseases with primary podocyte damage that are clinically manifested by the nephrotic syndrome. The pathogenesis of these podocytopathies is still unknown, and therefore, the search for biomarkers of these diseases is ongoing. Our aim was to determine of the proteomic profile of urine from patients with FSGS and MCD. Patients with a confirmed diagnosis of FSGS (n = 30) and MCD (n = 9) were recruited for the study. For a comprehensive assessment of the severity of FSGS a special index was introduced, which was calculated as follows: the first score was assigned depending on the level of eGFR, the second score—depending on the proteinuria level, the third score—resistance to steroid therapy. Patients with the sum of these scores of less than 3 were included in group 1, with 3 or more—in group 2. The urinary proteome was analyzed using liquid chromatography/mass spectrometry. The proteome pr...
A Proposal for a Serology-Based Approach to Membranous Nephropathy
Journal of the American Society of Nephrology, 2016
Primary membranous nephropathy (MN) is an autoimmune disease mainly caused by autoantibodies against the recently discovered podocyte antigens: the M-type phospholipase A2 receptor 1 (PLA2R) and thrombospondin type 1 domain-containing 7A (THSD7A). Assays for quantitative assessment of anti-PLA2R antibodies are commercially available, but a semiquantitative test to detect anti-THSD7A antibodies has been only recently developed. The presence or absence of anti-PLA2R and anti-THSD7A antibodies adds important information to clinical and immunopathologic data in discriminating between primary and secondary MN. Levels of anti-PLA2R antibodies and possibly, anti-THSD7A antibodies tightly correlate with disease activity. Low baseline and decreasing anti-PLA2R antibody levels strongly predict spontaneous remission, thus favoring conservative therapy. Conversely, high baseline or increasing anti-PLA2R antibody levels associate with nephrotic syndrome and progressive loss of kidney function, thereby encouraging prompt initiation of immunosuppressive therapy. Serum anti-PLA2R antibody profiles reliably predict response to therapy, and levels at completion of therapy may forecast longterm outcome. Re-emergence of or increase in antibody titers precedes a clinical relapse. Persistence or reappearance of anti-PLA2R antibodies after kidney transplant predicts development of recurrent disease. We propose that an individualized serology-based approach to MN, used to complement and refine the traditional proteinuria-driven approach, will improve the outcome in this disease.
Molecular pathogenesis of membranous nephropathy
Kidney International, 1992
for the removal of hemorrhoids, He presented with slight generalized edema, and subsequently unselective proteinuria (1.4 g/day) was discovered. He was transferred to the Nephrology Section and a renal biopsy was sent to the Department of Pathology of the University of Vienna, Allgemeines Krankenhaus. Light microscopy with serial paraffin sections revealed an even, modest thickening of all peripheral capillary loops of the entire glomerular basement membrane. The number of mesangial cells and the average area of the niesangium were normal; no inflammatory cells were detected in the glomerular tufts. Bowman's capsule and the vascular system were inconspicuous; the interstitial space was slightly edematous. Proximal tubules contained a few resorption droplets, which contained albumin and immunoglobulins on immunocytochemical examination. The tubular system appeared normal otherwise. Silver impregnation of the paraffin sections showed a serrated pattern of the basement membranes of the peripheral capillary loops that was caused by spikes extending from the subepithelial glomerular basement membrane. Immunocytochemical analysis disclosed abundant IgG, C3c, and C5b-9 in a punctate pattern in the basement membrane. Immune deposits were evenly distributed within the peripheral capillary walls and were of similar sizes; they formed a regular, discrete pattern. Weak staining for Clq was detected, but 1gM, IgA, and fibrinogen were absent. There was no staining in the mesangium for any of these molecules. Presentation of this Forum is made possible by an educational grant from Merck Sharp & Dohme International. This Forum was presented in Talloires, France, in May 1991.
Mediators of renal injury in membranous nephropathy
2009
Membranous nephropathy (MN) is a common glomerular disease characterized by podocyte injury and proteinuria, often in the nephrotic range. Heymann nephritis (HN), a rat model of MN, has contributed to elucidation of the under- lying pathogenic mechanisms which involve in situ formation of subepithelial immune deposits of antibody reactive with podocyte antigen(s) that produce glomerular injury by damaging and/or activating podocytes through comple- ment-dependent processes. Disorganization of the cytoskeleton with subse- quent redistribution of components of the slit diaphragm and loss of the glomerular charge barrier induces proteinuria in MN. C5b-9 in sublytic quanti- ties stimulates podocytes to produce proteases, oxidants, prostanoids, extra- cellular matrix components, and cytokines. Alterations of the cytoskeleton induced by C5b-9 also lead podocyte depletion through apoptosis and detach- ment of viable podocytes. Furthermore, complement components in proteinuric urine induce ...
Membranous nephropathy: the current state of the problem
Počki, 2023
Membranous nephropathy (MN) is a heterogeneous group of diseases characterized by a common histopathological picture in the form of diffuse thickening and changes in the structure of the glomerular basement membrane (GBM) as a result of subepithelial and intramembranous deposition of immune complexes and deposition of matrix material produced by affected podocytes. Podocyte injury resulting from the immune deposits increases glomerular permeability to plasma proteins, which results in protei nuria and potentially in nephrotic syndrome (NS). In the kidneys, in situ, immune complexes are formed, consisting of their own podocyte or exogenous antigens and autoantibodies produced for them, belonging to the immunoglobulin (Ig) G class. This leads to complement activation along the classical pathway with the formation of a membrane attack complex in the subepithelial space [1, 2]. J. Feehally, in his famous book "Comprehensive Clinical Nephrology" (2016), notes that the term membranous refers to thickening of the glomerular capillary wall on light microscopy of a kidney biopsy, but the condition now called membranous nephropathy is determined using immunofluorescence and electron microscopy. These methods reveal diffuse fine-grained immune deposits on immunofluorescence and electron-dense deposits in the subepithelial
Recent Advances in Membranous Nephropathy
2000
Membranous nephropathy (MN) is a common cause of the nephrotic syndrome in adults. The pathogenesis of MN, as defined in the experimental rat model of Heymann nephritis, involves antibodies that target antigens on the podocyte foot process and accumulate as immune deposits, activating complement, and leading to sublethal injury of the podocyte, as well as proteinuria. Similar mechanisms are now
Molecular Pathomechanisms of Membranous Nephropathy
Journal of the American Society of Nephrology, 2005
Membranous nephropathy (MN), the most common cause of idiopathic nephrotic syndrome in white adults, is characterized by an accumulation of immune deposits on the outer aspect of the glomerular basement membrane. In Heymann nephritis, the rat experimental model for MN, megalin-the target antigen of the nephritogenic antibodies-is expressed on the surface of podocytes, where immune complexes are formed, leading to complement activation and nephrotic-range proteinuria. However, megalin cannot be held responsible for human MN because it has not been found in human podocytes or detected in subepithelial immune deposits in patients with MN. Several potential antigens have been identified in so-called secondary forms of MN, but there is no real proof that these antigens are pathogenic. In a subgroup of infants with antenatal MN, neutral endopeptidase (NEP) has been identified as the first protein target on human podocytes of nephritogenic antibodies. The infants' mothers became immunized during pregnancy against NEP expressed on syncytiotrophoblastic cells because they were NEP deficient as a result of truncating mutations in the MME gene. Severity of neonatal renal disease was determined by the mothers' IgG response that led to the formation of the membrane attack complex of complement in the subepithelial deposits. Alloimmunization against NEP is a novel pathomechanism of MN that might also account for some cases of MN after renal or bone marrow transplantation. Other types of alloimmunization should be investigated in MN but also in other renal and nonrenal diseases, particularly those that affect the pediatric age.