Physiologie du complément et son implication dans la pathologie rénale

Transcription

1 Physiologie du complément et son implication dans la pathologie rénale Veronique Frémeaux-Bacchi Hôpital Européen Georges Pompidou Paris

2 Conflicts of Interest Served as an advisor or consultant and as a speaker for: Alexion Pharmaceuticals Served as consultant for Alnylam, Apellis, Bayer, Novartis and Roche Member of SAB for Alexion Pharmaceuticals

3 Objectifs : - Décrire la physiologie du complément. - Décrire brièvement l implication du complément dans les pathologies non néphrologiques - Expliquer l implication des voies du complément dans la pathologie rénale

4 Mechanisms of differential complement activation and regulation under physiological conditions

5 Complement System 24/24 Classical Pathway Lectin Pathway Alternative Pathway Ag-Ac terminal mannose groups Tick-over initiation C1q C1s and C1r C4, C2 MBL MASPs C3 -like or C3(H 2 O) FB FD C3a Ba Classical C3 convertase C4bC2a C3a Alternative C3 convertase Bb

6 Complement System Classical Pathway Lectin Pathway Alternative Pathway(VA) Ag-Ac terminal mannose groups Tick-over, Surfaces activatrices initiation C1q C1s and C1r C4, C2 MBL MASP1 and 2 C3 -like or C3(H 2 O) FB FD C3a Ba Classical C3 convertase C4bC2a C3a Alternative C3 convertase Bb Few min amplification CP C5 convertase (C4bC2a) C( C5 Properdin AP C5 convertase (Bb) C5a C5b9

7 Complement System Classical Pathway Lectin Pathway Alternative Pathway(VA) Ag-Ac terminal mannose groups Tick-over, Surfaces activatrices initiation C1q C1s and C1r C4, C2 MBL MASP1 and 2 C3 -like or C3(H 2 O) FB FD C3a Ba Opsonisation Classical C3 convertase C4bC2a Alternative C3 convertase Bb amplification AP C5 convertase (Bb) C5b-9 (MAC) C6 C7 C8 Phagocytosis C3a,C5a inflammation Link with adaptive immunity Bacterial lysis Recruitement of inflammatory cells Platelets and Endothelial cells activation

8 Inflammatory effects mediated by C5a 74 aa gp Quickly metabolised by carboxypeptdase to C5a des-arg C5a exerts potent chemotactic and proinflammatory effects Recruitment of inflammatory cells such as neutrophils Chemotaxis Lysosomal enzyme release Neutrophil aggregation C5a Enhances IL-6 and TNF secretion from monocytes CR1 and FcR expression Cell adhesion CR3 (CD11b/18) Platelet activating factor (PAF)

9 Defense against infection Microbes Dual role of complement C3 Permanent FB Protection of host cell membranes Bb Amplification Loop C5a Self Negatively charged cell surface polyanions (heparin, sialic acid, GAGs) Complement regulatory proteins Opsonisation Phagocytosis Chemotactic factors C5b C6 C7 C8 C9 MAC Elimination of microbes Protection of cell surface from deposits and complement 9 activation

10 Complement regulation Factor H CR1 CD59 CR1 (CD35) MCP (CD46) Factor I MCP DAF Endothelial cells DAF (CD55) C3 convertase C5 convertase MAC CFH CFI MCP DAF CR1 CD59

11 Factor H : First regulatory protein of AP Single polypeptide chain plasma glycoprotein; 155 kda 20 complement control protein modules (CCP/SCR) 60 aminoacids Functional domains Two major distinct binding sites Two separate binding sites for heparin GAG 7 19 Factor B Morgan et al., Nat. Struc. Mol. Biol 2010 Preventing AP activation through binding to host cell membranes

12 Regulation of the AP Occurs at mutiple steps through distinct mechanisms Crucial to restrain complement activation so as to prevent pathologic consequences Fluid phase and cell surface Inhibition of the C3 convertase formation FB FH Bb Dissociation of the C3 convertase Bb FH, DAF Elimination of on cells FI FH, MCP C3f i

13 The lectin patway is intimately connected to the CP and AP MASP-1 gene: MASP-1; MASP-3; MAp44 MASP-2 gene: MASP-2; MAp19 C1-inh and AT-III Surfaces displaying carbohydrates or acetyl groups cc MBL, ficolins, CL-K1/L1 (Pattern Recognition Molecules) MASP-1 C3 MASP 3 may be involved in the activation of the AP MASP-2 MASP-3 FB C4 C2 Pro-FD C4b2a FD C3 convertase Alternative Pathway

14 Role of complement in physiology Constant low level of complement activation Prevention of any amplification Limited complement response Regulators From Ricklin et al, Nature Immunol review, 2010

15 Danger signaling Complement and altered self REG Complement REG REG Cancer cell Normal cell Apoptotic cell Endothelial damage Endothelium is damaged by complement Damaged endothelium activates complement

16 Restricted protection for Red blood cells CD59 CR1 (CD35) CD59 CR1 (CD35) DAF (CD55) MCP (CD46) DAF (CD55) DAF and MCP protects cells by patrolling the surfaces and inactivating

17 Paroxysmal Nocturnal Haemoglobinuria Lack of expression of the GPI-anchored proteins on haematopoietic cells No CD59 and No CD55 on red blood cells Normal red blood cells are protected from complement attack by a shield of terminal complement inhibitors Without this protective complement inhibitor shield, PNH red blood cells are destroyed No CD59, no CD55 Complement Activation Intact RBC Anemia Hemoglobinuria Lack of complement regulation renders the cells extremely sensitive to complement mediated lysis

18 Beltrame et al, 2015 Biological functions of the complement system

19 Complement as a first line of defense against Pathogens AP Strong C response in cases of microbial intruders; No regulators C3(H20) Constitutive activation Microbes with terminal mannose groups L P MBL and Ficolins B Bb Cell lysis Trigger inflammation Promote the attachment of antigens to phagocytes The association of complement deficiencies with recurrent bacterial infections occurs predominantly with components of the AP (C3, Properdine, Factor I) and C5 to C8 Streptococcus pneumonia, Neisseria meningitidis

20 Infections à Nm : environ 150 déficits en protéines du complément diagnostiqués par le Service d Immunologie de Broussais -HEGP ( ) 5 à 10 nx cas depuis 10 ans / an : 1% par an des IIM Protéines de la voie finale commune C5 (20%); C6 (30%); C7 (40%); C8 (10%); C9 (1%) 90% Une ou plusieurs infections à Neisseria meningitidis Properdine Facteur D (1cas); C2 (1cas) Déficit acquis en C3 C3 NeF (1), FH (1), FI (2)

21 Clinical description of Nm C5 to C8 C9 Properdin Normal individual age at the firts episode (mean, year) to 3 Fold increase risk of disease 7000 to death (%) 5 to 7 35 to Recurrences 40-50% rare exceptionnal Transmission AR X-linked Effective complement system is pivotal for host resistance against Nm : Deficiency of the MAC pathway have an lifetime risk of Nm disease of fold compared with general population. The efficacy of vaccine in C deficient individuals has not been well evaluated (only opsonophagocytic protection)

22 Pathological activation of Complement Ie Age related effects, excessive acute or chronic tissue damage, biomaterials or transplants Imbalance between activation and regulation lead to an attack on host cells and trigger immune and inflammatory disaeses. From Ricklin et al, Nature Immunol review, 2010

23 Major mechanisms of the pathogenic involvement of complement in systemic and local disorders Rickling et al, 2017

24 Complement plays dual roles in the pathogenesis of SLE Protective features in that hereditary homozygous deficiencies of classical pathway components, such as C1q and C4, are associated with an increased risk for SLE. IC-mediated activation of complement in affected tissues On plasma Consomption of C3 and C4 levels On cells Low levels of CR1:proteolysis C3a, C5a C4b On tissues IC can not be eliminated Deposits of Ig and C Inflammation Cellular activation Complement activation in SLE has been viewed as a major cause of tissue injury 24

25 Acute Humoral Rejection : activation of complement at the site of tissu injury Anti HLA Class I Transplant Endothelium C1q + C4, C2 + + C 3 C5 C4d deposited at site of complement activation C 3b C3a / C5a MAC Endothelium destroyed Neutrophils in peritubular capillaries Arterial fibrinoid necrosis Acute tubular injury C4d C5-C9

26 The prototype of complement mediated disaese: Atypical HUS and C3 Glomerulopathy Atypical HUS C3G All age Mecanic anemia, thrombocytopenia and acute renal failure The outcome is variable : Severe with ESRD after the first episode (50% of cases) Early or late recurrences Complete remission mainly affects adolescents and adults Chronic progressive renal disease that is diagnosed on the basis of renal histological features Half of the patients present with nephrotic syndrome, the others with mild proteinuria, ESRD in 50% of cases after 10y Sporadic and less frequently familial forms (10%) Unfavourable prognosis Recurrence after renal transplantation with a possible phenotype switch : 26

27 ahus is the prototypic of the complement related disease 50 to 60% of patients with pathogenic variants in complement genes Gain of function Fremeaux-Bacchi et al, Blood, 2008 Roumenina et al, Blood 2012 Factor B C3 Goicoechea de Jorge et al. PNAS 2007 C3a Roumenina et al, Blood 2009 Bb C3 convertase CFH MCP Factor I Loss of function Dragon-Durey et al : JASN 2006 Warwicker et al. Kidney Int 1998 Venables et al, Plos Med, 2006 Richards et al. PNAS 2003 Noris, M et al. Lancet 2003 Thrombomodulin Kavanagh et al, CJASN, 2012 Fremeaux-Bacchi et al. J Med Genet 2004 Delvaeye M et al : N Engl J Med More than 1000 ahus patients studied around the world Two large cohorts with defined genotype-phenotype correlations published (Italy and France). Noris et al CJASN, 2010, Fremeaux-Bacchi et al., CJASN,2013

28 Loss of protection of endothelial cells against complement activation FB C5 C5a FH FI C5b >>>>>> >>>>>> C3 convertase C5 convertase MCP MAC C5b-9 Endothelial damage from complement attack Platelet activation Thrombi and thrombotic microangiopathy, mechanical hemolytic anaemia, thrombocytopenia, renal and other end-organ (brain, heart) ischemic damage C5 protein is the link between all complement anomalies identified in patients with ahus and thrombotic microangiopathy lesions

29 Eculizumab is a effective treatment in adult patients with ahus human IgG2 heavy chain constant region 1 and hinge Human FRs Ch2 CH3 hinge CDRs (murine origin) human IgG4 heavy chain constant regions 2 and 3 Overall renal survival (%) Number of ahus patients at risk P < 0,0001 French cohort Years with Eculizumab w/o Eculizumab Treated with Eculizumab Plasmatherapie Mortality: 6,8% in adults ESRF at 5 years follow-up 64% in adults vs 30% Fremeaux-Bacchi et al, personal data

30 Genetic or acquired dysregulation of the complement alternative pathway 6 pediatric series from various countries Netherlands South Italy France Spain India 2010 a Belgium 2012 b 2015 c 2015 d Korea 2015 e 2014 f Number of ahus children CFH mutation and CFH-CFHR1 hybrid gene (%) nd MCP mutation (%) nd CFI mutation (%) nd C3 mutation (%) nd CFB mutation (%) nd nd Combined complement mutations (%) nd nd THBD mutation (%) 7.8 nd nd Anti-FH antibodies (%) Total complement mediated HUS (%) nd DGKE mutation (%) nd nd nd a. Noris et al, 2010;b. Geerdink et al, 2012; c. Fremeaux-Bacchi et al, 2015, unpublished; d. Bernabeu-Herrero et al, 2015; e. Lee JM et al, 2015; f. Sinha et al, 2014

31 ahus: mostly, but not exclusively, a disease of complement dysregulation Study population (year of publication) France (2015)* International Italian Registry (2010) 3 Spain (2015) 4 Loss of function Gain of function Number of patients age at onset Adults Adults Adults CFH and hybrid genes** (%) MCP (%) CFI (%) C3 (%) CFB (%) 1 nd 0.9 Combined (%) 2 nd 0.9 THBD (%) Genetic Complement Dysregulation (%) Anti-CFH Ab (%) a. Noris et al, 2010;b. Geerdink et al, 2012; c. Fremeaux-Bacchi et al, 2015, unpublished; d. Bernabeu-Herrero et al, 2015; e. Lee JM et al, 2015; f. Sinha et al, 2014

32 ahus A disease of coagulation dysregulation? THBM Accelerates thrombin-mediated activation of Protein C Cofactor in the Factor I mediated cleavage of to i It : 1% Delvaeye et al, Neng J Med, 2009 US : 0 /118 Bu et al, JASN, 2015 Fr :2/ 203 (with CFH and DGKe) Fremeaux-Bacchi, CJASN, 2013 PLG Degradation of thrombi US: Hz PLG deficiency 4/ 36 and 3/118 MAF <0,1% Bu et al, JASN, 2014; Bu et al, JASN, 2015

33 Recessive mutations in DGKE causes ahus M Lemaire, V Fremeaux Bacchi et al. Nature Genetics, 2013 Intracellular lipid kinases Loss of DGKe in EC induces cell death, impairs angiogenic responses and leads to an prothrombotic phenotyps 1. Bruneau et al.; Blood to 4 % of ahus with pediatric onset 25% of children with onset below 1y Relapses during the 5 1st years; none after age 5 Progression to ESRD within the first year: < 10% But patients develop hypertension, hematuria, proteinuria and nephrotic syndrome and progress to ESRD by age 20 to 25 yrs Report of Complement mutation in DGKe associated ahus 3 1. Wesland et al.; 2. Sanchez Chinchilla et al.; 3. Sánchez Chinchilla et al. Clin J Am Soc Nephrol, 2014 Sep 5;9(9):1611-9

34 ahus: many risks factors Mutation in one of the six genes (CFH,CFI,MCP,C3,CFB) The term of Mutation is reserved to rare pathogenic sequence changes The Identification of the effects that each mutation causes on function of its protein product is mandatory. + Second mutation (3.3% of patients) and/or Commun polymorphisms (CFH; MCP; CFHR1) (Esparza-Gordillo et al, 2005;Fremeaux-Bacchi et al,2005; Abarrategui-Garrido et al, 2009 ) = + Trigger events Diarrhea and upper respiratory tract infections were frequent in children Pregnancy is the trigger event in 20% adult female patients with ahus mainly in the post partum period (Review in Noris et al, 2010 )

35 ahus investigations in 2018 Complement proteins levels: C3, C4, CFH, CFI (plasma) CD46 Anti Factor H Ab Genetic screening C3 level with ahus - Normal C3 does not eliminate the presence of a complement mutation NGS-Panel involving sequencing and analysis of the exonic regions of 7 genes: : CFH, MCP (CD46), CFI, C3, CFB, thrombomodulin, DGKE Home made and MRC Holland MLPA (Hybrid gene and deletion CFHR3-1)

36 The specificities of anti-fh antibody-associated ahus First described in 2005 : 3 cases in children Approximately 200 cases reported currently, mainly in childhood Frequency 6-10% (up to 25%) of ahus in European children, 50% in Indian children and 5% of ahus with adult onset Associated with CFH deficiency 80% with complete CFHR1-R3 deficiency 14% with novel or rare variant in complement genes Diagnosis : anti CFH antibody levels : standardization across laboratories Dragon-Durey et al, JASN 2005; 2010 Hofer et al, CJASN 2013; Sinha et al, KI 2013 Dragon-Durey et al, Nature Nephrol Review, 2016

37 In GC3, the most common acquired factors are autoantibodies to C3 convertase (C3Nefs) C3 NeF (50% to 80%) Bb C3 convertase Bb C3 Convertase C3 i i i i i i i i i i i i i i Schwertz et al Pediatr Allergy Immunol 2001 Sethi et al KI 2012 Servais et al 2013 Zhang et al CJASN 2012

38 Missense variants mapped onto protein structural models Statistical Validation of Rare Complement Variants Provides Insights into the Molecular Basis of Atypical Hemolytic Uremic Syndrome and C3 Glomerulopathy. Osborne et al, JI, 2018

39 Is there a role for complement in ANCA associated vasculitis pathogenesis? Lessons from the MPO-ANCA animal models Xia et al., Am. J. Pathol., 170: 52-64, 2007 Mice deficient in FB but not C4 were resistant to anti MPO IgG induced kidney disease

40 C5a and C5aR are crucial anti C5 mab AP Inflammation C5aR C5a B ellular activation C5 C3 C6 C5b Disease development is dependant on C5a-C5aR interaction but not C6 and MAC D Huugen et al. KI 71: , 2007, Schreiber et al. JASN 20: , 2009

41 The C5aR /CD88 small molecule antagonist CCX168 ameliorates anti MPO induced GN in human C5aR knockin mice Human C5R kockin mice +/- CCX168 treatment Daily administration of CCX168 markely reduced the severity of anti MPO induced GN Xia et al., JASN., 2014

42 What evidence for a complement activation in human AAV? The typical glomerular lesion in AAV is pauci-immune glomerulonephritis (IF studies find no immune deposits) Detection of renal deposition of complement components by IHC Gou et al., Kidney Int. 83: , 2012

43 Putative sequence of complement activation amplification in ANCA vasculitis Tissue damages enhance Complement activation C5b9 deposition on cells C5a release sc5b9 amplification of AP deposition on cells Bb Loss of AP control on cells Damage of EC Adapted from Cees et al., Kidney Int. 83: 16-18, 2012

44 Kidney disease with AP activation C3G ahus ANCA vasculitis Target of Complement activation Global (fluid phase) endothelial cells Neutrophils complement deficiency Hereditary 10-20% 50-60% und Triggers Acquired Link between complement and disaese Therapeutic with complement inhibitor C3 NeF/anti FH Ab (50-80%) und anti FH Ab (less 10%) yes (Pregancy, flu, infection) no Yes (TNF),i, C3dg C5b9 C5a/C5aR ongoing C5 (Eculizumab) C5a receptor inhibitor CCX168

45 Complex involvement of complement Figure 2 in kidney disaese American Journal of Kidney Diseases , DOI: ( /j.ajkd )

46 The new view of complement Leslie, Sciences 2012 Excessive Activation Defective regulation Removing an organ for transplantation unleashes complement mediated damage Age _related macular degeneration linked to CFH variant

47 Take home messages Friend Inhibition of precipitation of IC Promotes the clearance of immune complexes Eliminating antibody-coated bacteria, apoptotic cells Complement Or not Generation of anaphylatoxins C3a et C5a : Influx of inflammatory cells including PNN and monocytes Cells activation secondary to insertion of the MAC into cell membranes Soluble and membrane-bound complement regulators protect cells and tissues from unintended complement-mediated injury Defect of local protection from activation lead to a more severe kidney disease

48 Complement and disaeses

49 Progress of complement therapeutics toward clinical uses

50 Meeting in Royal Society, London. Hobart M. Immunology Today, 1985;5:212. Many immunologists hold that complement is baffling or irrelevant or, most conveniently, both but a recent meeting emphasized that complement is interesting and that it may be important, even only as an elegant model system.