academic trainees meeting – 5 th may, 2011
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Academic Trainees Meeting – 5 th May, 2011. Interesting aspects of complement regulation……. Matthew Pickering Wellcome Trust Senior Fellow in Clinical Science Consultant Rheumatologist. Complement activation protein deficiency. Classical pathway . C3 . Terminal pathway . Infection. - PowerPoint PPT PresentationTRANSCRIPT
Academic Trainees Meeting – 5th May, 2011
Interesting aspects of complement regulation……
Matthew Pickering
Wellcome Trust Senior Fellow in Clinical ScienceConsultant Rheumatologist
Complement activation protein deficiency
Terminal pathway
Recurrent Neisseria infections
C3
Infection
Classical pathway
SLE-like illness
Recurrent infection with encapsulated bacteria e.g. pneumococci, Haemophilus influenzae
Vasculitis, glomerulonephritis
Complement dysregulation
Terminal pathway dysregulation
Paroxysmal nocturnal haemoglobinuria
C1 inhibitor deficiency
[classical pathway dysregulation]
Hereditary angioedema
Alternative pathway dysregulation
Dense deposit disease,
Atypical haemolytic uraemic syndrome
renal thrombotic microangiopathy
Disorders of complement
Activation protein deficiency
‘too little’ complement
Tell us what might happen if we
therapeutically inhibit complement
Regulatory protein deficiency
‘too much’ complement’
Provide diseases in which complement inhibiting therapies
ought to be effective
C3b
C3
C3b C3b C3bFOREIGN SURFACE
C3b
‘C3b amplification loop’
Complement activation
lectin pathway
Bacterial Carbohydrate, ficolins
C4b2a
classical pathway
immune complexes
C3bBb
alternative pathway
‘always on’
C5 activation
MAC
C5a
MAC = membrane attack complex
C3b
C3
Complement regulation
lectin pathway
C4b2a
classical pathway
C3bBb
alternative pathway
MAC = membrane attack complex
iC3b C3b
CR1CD46CD59MAC
Factor I
DAF(CD55)
C1 inhibitor
C4bp C1 inhibitor Factor H
Factor I
iC3b
Factor H
Factor H
Physiological control of complement activation
REGULATORS
Complement dysregulation and disease:
ACTIVATORS
Loss of function Gain of function
The balance is influenced by mutations (extreme) and and/or polymorphisms (‘fine tuning’)
What does factor H do? Critical negative regulator of the alternative pathway and C3b
amplification loop
What happens to C3 levels in individuals with complete genetic deficiency of CFH?
Uncontrolled spontaneous activation of the alternative pathway and secondary consumption of C3
Why is factor H important? It is associated with human disease:
Dense deposit disease
mutations
rare
‘protective’ and ‘at risk’polymorphisms
common
Dense deposit disease Electron-dense transformation of the glomerular basement
membrane
Glomerular C3 staining in DDD
DDD retinopathy
Dense deposit disease
C3b
C3
C3bBb
Factor H
B, D
C3 nephritic factor
Anti-factor H
Associated with plasma C3 activation:
Dense deposit disease Animal models:
Spontaneous porcine factor H deficiency and gene-targeted factor H-deficient mice
Profound plasma C3 depletion – 5% of normal C3 levels
Spontaneous renal disease – ‘murine/porcine DDD’
Factor H deficiency
Wild-type
C3 staining wild-type
0
200
400
600
Cfh-/-
Pla
sma
C3
- mg/
l
Dense deposit disease What have the animal models taught us?
The renal disease does not develop if activation of C3 is blocked
The renal disease does develop if C5 activation is blocked Dense deposits still develop Glomerular inflammation reduced but not absent
Murine dense deposit disease is dependent on the ability to activate C3 but not C5
Glomerular basement membrane deposits in mice with combined
deficiency of factor H and C5
Pickering MC, et al. PNAS 2006 103(25):9649-54.
Human complement deficiency
DeficiencyState:
Plasma C3:
Factor I
low absent
C3
Associations: Recurrent infection
immune complex-mediated renal diseasee.g. MPGN type I
Factor H
low
Dense depositdisease
C3b iC3b, C3d
Pickering MC, Cook HT. Clin Exp Immunol. 2008 51(2):210-30.
Plasma C3 regulation Continuous activation of C3 occurs in plasma through
the C3 ‘tick-over’pathway
C3b
C3
C3bBb
Factor H
C3b
Factor I
iC3b
C3dC3c
Factor BFactor D
Dense deposit disease Administration of factor I to mice with combined deficiency
of H and I restores GBM C3 staining
0 24 48 72
0
50
100
150
200
hours
Pla
sma
C3
leve
ls (m
g/l)
injections
Rose KL et al. J Clin Invest. 2008 118(2):608-18.
Why is factor H important? It is associated with human disease:
Dense deposit diseaseAtypical haemolytic uraemic syndrome
mutations
rare
‘protective’ and ‘at risk’polymorphisms
common
Atypical haemolytic uraemic syndrome
Atypical Haemolytic uraemic syndrome
renal thrombotic microangiopathy
Alternative pathway dysregulation
Associated with:
COMPLEMENT MUTATIONSLoss of function mutations in regulators
• Factor H • Mutations• Hybrid gene (copy number variation)
• Factor I• MCP (CD46)
Gain of function mutations in activation proteins• C3• Factor B
ACQUIRED COMPLEMENT DYSREGULATIONAnti-factor H autoantibodies
Atypical Haemolytic uraemic syndrome – factor H mutations
Factor I
iC3b
C3b
C3
B, D
C3bBb
HOST SURFACERENAL ENDOTHELIUM
C3b C3b C3b C3b C3b
C5 activation
MAC C5a
CD46
C3 regulation
Surface recognition
Murine model of factor H-associated atypical haemolytic uraemic syndrome Gene-targeted factor H-deficient mice transgenically expressing a mutant
mouse factor H protein (FH16-20)
Cfh-/-FH16-20Cfh-/-
0
25
50
75
100
Pla
sma
C3
- mg/
l
wild-type mouse CFH Mutated mouse FH16-20
Renal histology in Cfh-/-.FH16-20
Murine model of factor H-associated atypical haemolytic uraemic syndrome Use this model to determine contribution of C5 activation to renal injury
Spontaneous renal disease does not occur in C5-deficient Cfh-/-FH16-20 animals
Murine model of factor H-associated atypical haemolytic uraemic syndrome Cfh-/-FH16-20 animals are hypersensitive to experimentally triggered renal
injury – this injurious response is C5 dependent
C3
C9
Atypical haemolytic uraemic syndrome - therapy C5 inhibition successful in case reports – examples:
Eculizumab for aHUS – N. Engl. J. Med. 2009 360:5 pp542-543 Eculizumab for congenital aHUS – N. Engl. J. Med. 2009 360:5 pp544-6
Open Label Controlled Trial of Eculizumab in Adult Patients With Plasma Therapy-sensitive / -resistant Atypical Hemolytic Uremic Syndrome (aHUS)
Successful outcomes announced in ASN 2010 meeting http://clinicaltrials.gov/ct2/results?term=eculizumab
Why is factor H important? It is associated with human disease:
Dense deposit diseaseAtypical haemolytic uraemic syndrome
mutations
rare
‘protective’ and ‘at risk’polymorphisms
common
Factor H and Age-related macular degeneration
Factor H and AMD – the ‘Y402H’ polymorphism
From Sofat et al., Atherosclerosis 213 (2010) 184-90
Alternative pathway dysregulation
Age-related macular degeneration
Factor H and Age-related macular degeneration
Ocular drusen
Associated with:
Polymorphic variants in:Regulators• Factor H Y402H ‘at risk’
V62I ‘protective’
activation proteins• C3 C3FF ‘at risk’
• Factor BBf32Q ‘protective’
Age-related macular degeneration
Functional differences inthe Valine62Isoleucine CFHpolymorphism
62Isoleucine more efficient at preventing red cell lysis
14nM vs. 22.6nM at 50% lysis
62Valine
62Isoleucine
Factor H and Age-related macular degeneration
Age-related macular degeneration
Complement dysregulation and eye disease – age-related macular degeneration
Dense deposit disease
mutations
alternative pathway activation
Ocular drusen
‘at risk’polymorphisms
‘protective’polymorphisms
DDD retinopathy
Factor H 402H*Factor H 62VFactor B 32R
C3F
Factor H 402Y*Factor H 62IFactor B 32Q
C3SCFHR1/3 deletion*
*functional consequences not understood
Factor H null allelesC3 3923∆DG
Why is factor H important? It is associated with human disease:
Dense deposit diseaseAtypical haemolytic uraemic syndrome
mutations
rare
‘protective’ and ‘at risk’polymorphisms
commonAge-related macular
degeneration Meningococcal sepsis
Factor H and susceptibility to meningococcal infection
Meningococcal sepsis
The factor H family
Why are the factor H-related proteins important? They are associated with human disease:
mutations
rare
‘protective’ and ‘at risk’polymorphisms
common
The factor H family: copy number variation
CFH CFHR3 CFHR1 CFHR4 CFHR2 CFHR5Most frequent CFH-CFHR allele
Deletion homozygotes: African American 16%Hageman et al, Ann. Medicine 2006 European Americans 4.7%
CFH CFHR4 CFHR2 CFHR5CFHR1-3 deletion allele polymorphism (common)
Others (uncommon - <1%)
CFH CFHR1 CFHR4 CFHR2 CFHR5
CFH CFHR3 CFHR4 CFHR2 CFHR5
CFH CFHR3 CFHR2 CFHR5
CFH CFHR3 CFHR1 CFHR3 CFHR1 CFHR4 CFHR2 CFHR5
CFH CFHR3 CFHR1 CFHR1 CFHR4 CFHR2 CFHR5
Why are the factor H-related proteins important? They are associated with human disease:
‘protective’ and ‘at risk’polymorphisms
commonAge-related macular
degeneration
CFHR1-3 deletion allele polymorphism
associated with protection against
AMD
Mol Immunology 44 (2007):3921.
Complement therapeuticsPathologies in which
complement is activated
Complement therapeuticsExamples of the many complement inhibitors in development
Eric Wagner and Michael Frank Nature Reviews 2010, vol. 9, 43-56.
Thanks Elena Goicoechea de Jorge Katherine Vernon Mitali Patel Kirsten Rose Talat Malik Sharmal Narayan Marieta Ruseva Tamara Montes Lola Sanchez-Nino
Danielle Paixao-Cavalcante Fadi Fakhouri Terence Cook Marina Botto Santiago Rodriguez de Cordoba Veronique Fremeaux -Bacchi Patrick Maxwell Danny Gale