1 / 42

Podocyte and food antigens in membranous nephropathy

Podocyte and food antigens in membranous nephropathy. Pierre Ronco INSERM Unit 702 and Division of Nephrology, Tenon hospital, Paris, France. ECP, Helsinki, 2011 August 30th. Membranous Nephropathy. Major cause of nephrotic syndrome and chronic renal failure.

grazia
Download Presentation

Podocyte and food antigens in membranous nephropathy

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Podocyte and food antigens in membranous nephropathy Pierre Ronco INSERM Unit 702 and Division of Nephrology, Tenon hospital, Paris, France ECP, Helsinki, 2011 August 30th

  2. Membranous Nephropathy Major cause of nephrotic syndrome and chronic renal failure

  3. Aetiologies of membranous nephropathy • 30% associated with : - infections - cancers - autoimmune diseases - drugs • 70% « idiopathic forms » Proteinuria is complement - dependent , and may • involve production of oxygen free radicals and metalloproteases

  4. Membranous Nephropathy: IgG Subclass Distribution Ohtani et al, Nephrol Dial Transplant, 2004, 19:574

  5. Possible mechanisms of the formation of subepithelial deposits Serum Sickness Heymann nephritis « Planted » antigen Glassock , New Engl J Med 2009, 361:81

  6. Heymann nephritis Megalin, the target antigen of HN Renal BB IgG deposits Podocytes Activation of complement Rat: megalin Human? Y Y Y Y GBM Y Y Y Proteinuria Y Y Y Endothelium In situ formation of immune deposits Kerjaschki and Farquhar

  7. From rats to men : Allo-immune neonatal MN1982-2002

  8. The case : Hugo D. (male gender) • 34 Wks of gestation : oligohydramnios and enlarged kidneys • 38 Wks : birth • 1st Days of life : respiratory distress and oligoanuria, followed by nephrotic range proteinuria and increased blood pressure • 4 Wks : CT-guided kidney biopsy • Negative tests for syphilis, toxoplasmosis, cytomegalovirus and hepatitis -B virus infections • Negative Coombs’ test. Normal levels of complement components at day 35

  9. NEP after before NEP NEP NEP mother control 1 2 1 2 175 C5b-9 83 Blot: anti-NEP mAb anti-NEP IgG PLACENTA MOTHER FETUS IgG Infant born with MN and nephrotic syndrome Debiec et al. N Engl J Med 2002, 346:2053

  10. Potential mechanisms of albuminuria Green IgG green - IgG Red NEP red - NEP Blue C5b-9

  11. Induction of neonatal renal disease in pregnant rabbit by injection of human maternal IgG NEWBORN RABBIT KIDNEY Human IgG NEP

  12. PLACENTA FETUS MOTHER Genetic defect Podocytes NEP NEP deficient NEP Y Y Y Y GBM Y Y Y Y M C NEP Endothelium anti-NEP IgG C5b-9 IgG Infant born with MN and nephrotic syndrome Why did the mother become immunized without developing the renal disease ? IgG (Debiec et al. Lancet. 2004)  Feto-Maternal Allo-Immunization with antenatal Glomerulopathies (FMAIG)

  13. Western blotting of glomerular proteins with serum from patients with iMN Beck et al, New Engl J Med, 2009, 361:11

  14. Expression of PLA2R in normal kidney and glomeruli Beck et al, New Engl J Med, 2009, 361:11

  15. GWAS analysis of patients with idiopathic MN • Three cohorts • Controls : ethnically matched • Illumina platform : 300,000 SNPs • Bioinformatics analysis Stanescu et al, New Engl J Med, 2011, 364: 616

  16. Single Nucleotide Polymorphisms (SNPs) • Single base mutation in DNA • Most simple form of genetic polymorphism • 90% of all human DNA polymorphisms • Occur 0.5-10 per every 1 000 base pairs • Not uniformly distributed • > 1, 000, 000 SNPs identified • SNP in a coding region can be • Synonymous (silent mutation) • Non-synonymous (missense or nonsense mutation)

  17. Principle of pangenomic (GWAS) studies

  18. A risk HLA-DQA1 allele is associated with iMN and may interact with PLA2R alleles French (n=75 ; c=157) Dutch (n=146 ; c=1832) British (n=335 ; c=349) All patients (n=556; c=2338) Stanescu et al, New Engl J Med, 2011, 364: 616

  19. Conclusions • An HLA-DQA1 allele on chromosome 6p21 is most closely associated with idiopathic membranous nephropathy in persons of white ancestry • This allele may facilitate an autoimmune response against targets such as variants of PLA2R1 • Our findings suggest a basis for understanding this disease and illuminate how adaptive immunity is regulated by HLA • The risk of iMN is higher with the HLA-DQA1 allele than with the PLA2R1 allele, suggesting that the HLA-DQ1 allele might favor autoantibody targeting also other antigens

  20. PLA2R autoantibodies and PLA2R glomerular deposits in membranous nephropathy Debiec and Ronco, New Engl J Med, 2011, 364 :689

  21. Are there other antigens on the horizon in patients with idiopathic MN ?

  22. Screening of MN sera reactivity with podocyte « proteome » Human podocyte lysates kDa 110 80 Western blot analysis 47 32 24 1 2 3 4 5 6 7 8 9 Patients’ sera Different autoantibody profiles

  23. Identification of antigens Differential extraction Human podocyte lysate Ion exchange chromatography MALDI-TOF MS 2D-electrophoresis Identification MALDI-TOF MS LC-MS/MS Western immunoblotting with patient’s serum Silver staining

  24. Candidate autoantigens recognized by autoantibodies in sera from MN patients > 10 Cytoplasm/cytoskeletal proteins « Metabolic » proteins Molecular chaperones Cytoskeletal proteins

  25. J Am Soc Nephrol 21 : 507-519, 2010

  26. Initiation Progression Podocytopenia Proteinuria Podocytes Cytoskeletal changes Altered intracellular transport Lack of proliferation DNA damage Apoptosis ROS Activation of complement Proteases Y Y Y C5b-9 Y C5b-9 Y GBM Y Y Detachment Y degradation Y Y Endothelium Progression Renal failure NEP PLA2R SOD2 Aldose reductase Enolase (Wakui et al, 1999) Stress proteins Cytoskeletal proteins Mechanisms of immune complex formation and podocyte injury in MN

  27. A role for nonnative antigens? Serum Sickness Heymann nephritis « Planted » antigen Glassock , New Engl J Med 2009, 361:81

  28. Anti-BSA antibodies in patients with MN Debiec et al, NEJM 2011, 364 : 2101

  29. IgG binding of BSA synthetic peptides MN patients Controls MNM A B Peptide Peptide BSA HSA BSA HSA Debiec et al, NEJM 2011, 364 : 2101 CDEFKADEKKFWGKYLY CTAFHDNEETFLKKYLY

  30. Circulating BSA in patients with MN B 2D electrophoresis and immunoblot ELISA BSA Debiec et al, NEJM 2011, 364 : 2101

  31. Colocalization of BSA and IgG in immune deposits BSA IgG Green BSA Red IgG

  32. Reactivity of eluted IgG Biopsy specimen stained for IgG subclasses IgG1 IgG2 Patient with BSA in biopsy 1 4 1 4 BSA HSA IgG3 IgG4 Patients without BSA in biopsy BSA Debiec et al, NEJM 2011, 364 : 2101 1 4 1 4 1 4 1 4

  33. Role of BSA in the pathophysiology of MN Processing Digestion BSA Absorption of antigen from the intestinal tract APC T cell Y Y Y Y Y Y B cell Y Y Y Y YYY Anti-BSA Antibodies

  34. Association with disease activity 10 IgG subclass 1 2 3 4 Proteinuria g/l 5 initial disease 2004 2004 2005 2006 2008 2006 relapse Circulating BSA remission 2008 1000 ng/ml 500 2004 2006 2008

  35. What do these results teach us? • The repertoire of antigens involved in « idiopathic » MN  may include nonglomerular antigens • Food cationized BSA and/or abnormal processing of BSA in the GI tract in young children may lead to passage in the blood of cationic BSA, immunization, and in situ formation of immune complexes (Border et al, J Clin Invest, 1982, 69:451) • These cases point to a role for environmental factors in the pathogenesis of MN

  36. The spectrum of human membranous nephropathies • Neonatal, alloimmune : NEP • Early childhood MN : BSA • « Idiopathic » MN - 70-80% : PLA2R (+ other specificities:AR, SOD2, enolase..?) - 20-30% : other Ags including food/environmental Ag (BSA) • « Secondary » MN Ags to be identified • Graft MN - Recurrent : PLA2R (and other antigens) - de novo : allo-immune

  37. TENON CENTER OF NEPHROLOGY Acknowledgments Paediatricians • Bergamo (I) • G. Remuzzi • M. Abbate • Nijmegen (NL) • J. Wetzels • J. Hofstra • UK • R. Kleta (London) • P. Mathieson (Bristol) • Rees (Vienna) • CNG (Evry) • D. Bacq-Daian V. Guigonis (Limoges, F) A. Bensman (Paris, F) G. Deschênes (Paris, F) T. Ulinski (Paris, F) J. Nauta (Rotterdam, NL) F. Janssen (Brussels, B) J. Nortier (Brussels, B) D. Bockenhauer (London, UK) M. Kemper (Hamburg, D) B. Stengel (Paris, F)

  38. Anti-PLA2R antibody in membranous nephropathy Europe + Asia N=466 64.5% N=45 4.4% N=14 28% N=18 17% N=13 15% N=90 0% N=153 0% 100 75 Positive for anti-PLA2R (%) 50 25 DC HC iMN LN-MN Cancer HBV GvH Secondary MN Debiec ,Tesar and Ronco; Hoxha et al, NDT 2011; Qin et al, JASN 2011

  39. Anti-PLA2R antibody in idiopathic membranous nephropathy N=60 80% N=16 43% N=100 52% N=81 72% N=25 68% N=42 57% N=142 65% 100 75 Positive for anti-PLA2R (%) 50 25 iMN China iMN Italy iMN Dutch iMN France iMN Germany iMN Czech iMN Japan IFA Debiec ,Tesar and Ronco; Hoxha et al, NDT 2011; Qin et al, JASN 2011

More Related