5-2. C3 glomerulonephritis and Dense Deposit Disease. Francesco Emma (eng)
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Transcript of 5-2. C3 glomerulonephritis and Dense Deposit Disease. Francesco Emma (eng)
C3 glomerulonephritis and Dense Deposit Disease
Francesco Emma
Division of Nephrology and DialysisBambino Gesù Children’s Hospital, IRCCS
Rome, Italy
Leslie M., Science 2012
The area of complement….
MPGN Type ISubendothelial depositsWest et al, J Pediatr 1965
MPGN Type II / DDDIntramembranous deposits Galle, Thesis 1962; Habib et al, Kidney Int 1975
MPGN Type IIISubendothelial and subepithelial depositsBurkholder et al, Am J Pathol 1969Anders et al, Virchows Arch A Pathol Anat Histol 1997Strife et al, Clin Nephrol 1984
MPGN – “classic classification”
19 patients with unusual glomerulonephritis and:
- C3NeF positivity (7), CFH (3), CFI (2) or MCP (1) mutations
- overt mesangial and epimembranous C3 deposits
- absence of dense intramembranous deposits
- no Ig deposition
C3GN
• Proteomic profile of microdissected glomeruli:C3, C4, C5, C6, C7, C8, FHR1, FHR5….
• Very similar profile between DDD and C3GN
Sethi et al Kidney Int 2009; Sethi S et al Clin J Am Soc Nephrol 2011
Evidence for a role of complement in DDD/C3GN in humans
DDD C3GNMesangial proliferation 45% 40%MPGN 35% 55%Crescentic / Exudative GN 10% 5%
Servais A, J Med Genet 2007Walker PD et al, Modern Pathol 2007
Fakhouri F et al, Nature Rev Nephrol 2010Sethi S, Kidney Int 2012
Histology in DDD and C3GN
Walker PD et al, Modern Pathol 2007
MPGN Mesangial proliferation
Diffuse endocapillaryproliferation
Crescentic
Glomerular lesions in DDD
Walker PD et al, Modern Pathol 2007 Sethi S et al, Clin J Am Soc Nephrol 2011
DDD C3GN
The diagnosis of DDD requires electron microscopy
Sethi S, Kidney International (2012) 82, 465–473
MPGNMesangial proliferationDiffuse endocapillary
proliferation
Glomerular lesions in C3GN
Sethi S and Fervenza FC, Semin Nephrol 2011
Mesangial proliferative GN and MPGN represent a continuum
New classification based on C3: MPGN1 / DDD / GN-C3
Sethi S and Fervenza FC, Semin Nephrol 2011Sethi S and Fervenza FC, NEJM 2012
*Servais et al, Kidney Int 2012; Dragon-Durey et al. JASN 2004;Vaziri-Sani et al. Kidney Int 2006; Leroy V et al. Ped Nephrol 2011
*
DDD C3GN
New classification based on the MPGN pattern
MPGN1
Servais et al, Kidney Int 2012
MPGN1 can also be secondary to dysregulation of the complement alternative pathway
Zipfel and Skerka, Nat Rev Immunol 2009
A simplified view of the complement system
Sethi S, Fervenza FC NEJM 2012
Complement-mediated MPGN
inflammation
Torreira et al, PNAS 2009
C3bBb
C3 convertase
Sethi S, Fervenza FC NEJM 2012
Rodríguez de Córdoba S et al., Biochem Biophys Acta, 2011
C3 convertase
The C3 convertase can be activated in thefluid-phase or on cell surfaces
Adapted from Rodríguez de Córdoba S et al., Biochem Biophys Acta, 2011
The C3 convertase can be activated in thefluid-phase or on cell surfaces
• Mutation in the C3 gene (923ΔDG) which lacks 2 amino acids• Generates an active C3-convertase that is:
- normally regulated by DAF on the surface of endothelial cells- resistant to decay by factor H in the plasma
Conclusion:fluid phase-restricted dysregulation of the AP
C3 mutations in DDD
C-terminal regionsurface binding(glycosaminoglycans/heparins)
Rodríguez de Córdoba S et al., Biochem Biophys Acta, 2011
The C3 convertase can be activated in thefluid-phase or on cell surfaces
C-terminal regionsurface binding(glycosaminoglycans/heparins)
Rodríguez de Córdoba S et al., Biochem Biophys Acta, 2011
CFH domain mutations in aHUS and DDD
The role of C3 vs. C5 in MPGN
Goicoechea de Jorge, JASN 2011 Rose et al, J Clin Invest, 2008Pickering et al. Nat Genet 2002
Pickering et al. PNAS 2006
Cfh-/- FHD16-20 miceCfh-/- mice
aHUSMPGN
C3 C3
Dependent on C3>>C5 Dependent on C5
Cfi-/- C5-/- or anti-C5Prevented if:
Worsen if: C3 activation
C5-/- or anti-C5Improved if:
Complement dysregulation in kidney diseases
C3 levels in C3G
Servais et al, Kidney Int 2012
Plasma C3 regulation
Adapted from Smith et al. Mol Immunol 2011
Physiopathology of DDD/C3GN
• C3 nephritic factor (C3NeF):- IgG binding to neoepitope on alternative C3 convertase (C3bBb)- Stabilizes C3bBb against intrinsic and extrinsic decay- Present in all MPGN subtypes (DDD: 55% adults and 80% children)- High degree of inter-/intraindividual variability – poor predictive valueSchwertz et al, Acta Paediatr 1986; Schwertz et al, Pediatr Allergy Immunol 2001
• CFH (mini-)antibody:- Binds to CFH SCR3 and inhibits CFH cofactor activity- Phenotype DDDMeri et al, J Exp Med 1992; Jokiranta et al, J Immunol 1999
• CFB autoantibody:- Binds Bb- Similar effect as C3NeF- Enhances C3 conversion- Phenotype DDDStrobel et al, Mol Immunol 2010
DDD / C3GN: autoimmune forms
What epitopes do they bind and how tightly ?
Do they all stabilize the convertase to the same extent ?
Do they act on cell surface ?
Do differences correlate with the phenotype ?
Do they disappear spontaneously ?
C3NeF: still poorly understood…
Gene / Protein Mutation / Variant Function Phenotype Reference
CFH Mutations:- homo- / compound heterozygous- SCRs 1-4 (regulatory domain)- Cys residues (tertiary structure)
- Intact surface binding- Reduced C3b binding- Loss of CFH cofactor and decay accelerating activity
DDDC3GN
Levy, Kidney Int 1986Meri, J Exp Med 1992Vogt, Pediatr Nephrol 1995Ault, J Biol Chem 1997Dragon-Durey, J Am Soc Nephrol 2004Licht, Kidney Int 2006Habbig, Kidney Int 2009
CFH Polymorphisms:- Y402H (SCR 7)
- Impaired C3b / heparin binding- Impaired CFH cofactor activity
DDD Hageman, Proc Nat Acad Sci 2005Abrera-Abeleda, J Med Genet 2006Abrera-Abeleda, J Am Soc Nephrol 2011
CFHR3-1 CNV:- CFHR3-1 hybrid gene
- Not tested- ?Dominant negative effect
C3GN Malik, J Am Soc Nephrol 2012
CFHR5 CNV:- Duplication within CFHR5 exons 2/3
- Not tested- ?Dominant negative effect
C3GN Gale, The Lancet 2010
CFHR5 Polymorphisms - Not tested DDD Abrera-Abeleda, J Med Genet 2006Abrera-Abeleda, J Am Soc Nephrol 2011
C3 Mutations:- Heterozygous deletion
- C3mut resistant to cleavage by C3bBb - C3mut convertase – resistant to CFH inactivation
DDD Martinez-Barricarte, J Clin Invest 2010
C3 Polymorphisms - Not tested DDD Smith, J Am Soc Nephrol 2007Abrera-Abeleda, J Am Soc Nephrol 2011
DDD / C3GN: genetic formsCourtesy of Christoph Licth
No established therapy
Some cases may spontaneously improveSome patients have a relapsing course
Immune-suppressive drugs (PDN, CsA, MMF) may be beneficial in some cases, in particular if evidence of renal inflammation:- anecdotal reports and retrospective cohort studies- generally partial responses
Anti-C5 may be beneficial in some, but not all patients
Treatment of DDD / C3GN
Vivarelli et al, New England J Med 2012
Treatment of DDD with eculizumab
NB: not all patientsrespond so well
NB: expensive!
Presenting symptom in C3G
2 7 9
Kidney International 2012
Atypical APGN
Kidney International 2012
Atypical APGN
Thank you!Thank you!