Inflammasomes and autoimmune diseases

Transcription

1 Inflammasomes and autoimmune diseases Michael McDermott Section of Musculoskeletal Disease,, University of Leeds, UK

2 Definition of autoimmunity Breakdown of mechanisms for self-tolerance - induction of an immune response against components of self Aberrant B and T cell responses lead to breaking of tolerance - immune reactivity towards native antigens Adaptive immune system plays predominant role in the eventual clinical expression of autoimmune disease Organ-specific autoantibodies may predate clinical disease expression by years (e.g CCP, dsdna, ICA)

3 Genetic and Cellular basis for Autoimmunity Inflammatory Disorder Gene/ Protein Cellular Distribution/Defect Monogenic Autoimmune Diseases APS-1/APECED IPEX AIRE/AIRE FOXP3/FOXP3 Thymic epithelium/neg T cell selection Regulatory T cells/immunomodulation ALPS FAS/FAS Polygenic Autoimmune Diseases Widespread/lymphocyte apoptosis SLE, T1D, AITD RA, SLE Most autoimmune diseases CTLA-4/CTLA-4 PTPN22/PTPN22 MHC associations Regulation of T lymphocyte activation Regulation of T lymphocyte activation Antigen presentation, T cell function, including B cell help

4 Problems encountered with the autoimmunity paradigm in certain diseases Some diseases lack specific autoantibodies ankylosing spondylitis Difficult to prove role of cell-mediated immunity - Behçet s Syndrome Autoantibodies may be secondary e.g. apoptosis Diseases lacking MHC associations Crohn s Disease Lack of efficacy of therapies e.g multiple sclerosis Heterogeneous clinical disease expression seronegative forms of rheumatoid arthritis (RA)

5 Innate Immunity Rare Monogenic Autoinflammatory Diseases FMF, TRAPS, HIDS, PAPA Blau Syndrome Adaptive Immunity Polygenic Autoinflammatory Diseases Crohn s Disease, Ulcerative Colitis Degenerative diseases e.g. osteoarthritis Gout/Pseudogout/other crystal arthropathies Some categories of reactive arthritis and psoriasis (no MHC associations) Self-limiting inflammatory arthritis including diseases clinically presenting as RA Storage Diseases/Congenital Diseases with associated tissue inflammation Non-antibody associated vasculitis including Giant Cell Arteritis Idiopathic Uveitis, Acne and Acneform associated diseases Erythema Nodosum associated disease, including Sarcoidosis Mixed Pattern Diseases with MHC associations and autoinflammatory components Ankylosing Spondylitis Reactive Arthritis Psoriasis/Psoriatic Arthritis Behçet s Syndrome Uveitis (HLA-B27 associated) Classic Polygenic Autoimmune Diseases (Organ Specific and Non Specific) Rheumatoid Arthritis Coeliac Disease, Primary Biliary Cirrhosis Autoimmune gastritis/pernicious anaemia, Autoimmune Thyroid Disease Addison s Disease, Pemphigus, Pemphigoid, Myasthenia Gravis Dermatomyositis/polymyositis/scleroderma Vitiligo, ANCA-associated Vasculitis Type 1 diabete, Systemic Lupus Erythematosus Rare Monogenic Autoimmune Diseases ALPS, IPEX, APS-1/APECED Anti-B cell and Anti-T cell Therapy

6 NALPs in vitiligo and hypertension Jin Y et al. NALP1 in vitiligo-associated multiple autoimmune disease. N Engl J Med : NALP1 SNPs associated with several autoimmune and autoinflammatory diseases, implicating innate immunity in the pathogenesis of these disorders these diseases include autoimmune thyroid disease (Graves' disease and autoimmune hypothyroidism), Addison's disease, rheumatoid arthritis, psoriasis, pernicious anaemia, and SLE among patients with generalised vitiligo NALP1 expressed in T-lymphocytes, granulocytes and monocytes T. Omi et al. An intronic VNTRs of the cold-induced autoinflammatory syndrome 1 (CIAS1) gene modifies gene expression and is associated with essential hypertension. Eur J Hum Genet : inflammation oxidative stress-related genes in development of hypertension

7

8 NALP1 Inflammasome earlier SPRY Pyrin CC bzip PYD MDP NALP1 ASC PYD NACHT LRR FIIND PYD CARD Pro-caspase-1 Caspase-1 CARD Caspase-1 CARD CARD Pro- IL1β IL-1β activation IL1β

9 NOD2 signalasome mutations in the NACHT leads to BLAU SYNDROME mutations in the LRRs leads to CROHNʼs DISEASE MDP/DAP? CARD CARD NACHT LRR CARD Kinase NF-κB

10 NALP3 Inflammasome SPRY Pyrin CC bzip PYD NALP3 PYD NACHT LRR MDP Uric Acid ATP Cytosolic DNA PYD FIIND ASC CARD Cardinal CARD CARD Pro-caspase-1 CARD Caspase-1 Caspase-1 Pro- IL1β IL1β

11 NALP3 is upregulated in synovium of RA patients compared to OA A B Detection of NALP3 mrna in synovial tissue by in situ hybridisation A. NALP3 expressed in both lining and sublining in RA synovium B. Negative control using NALP3 sense probe NALP3 (cryopyrin), ASC, and pyrin mrna expression was significantly raised in RA compared to OA Rosengren et al. (2005), Ann Rheum Dis. 64:

12 DAS28 response criteria and methods Infliximab regime / sample collection Wk 0 Wk 2 Wk 6 Wk 14 PBMC mrna cdna qrt- PCR ASC NALP3 Bingham et al (2004), Rheumatology 43:

13 Pre-therapy baseline levels of NALP3 were predictive of response to treatment NALP3 expression p=0.04 Lower baseline NALP3 mrna levels in RA patients subsequently responding to infliximab treatment compared to non-responders 0 Responders (n=12) Non-Responders (n=11) Mann-Whitney U test.

14 NALP3 mrna levels were further decreased from baseline in response to infliximab treatment n=12 15 p=0.007 NALP3 expression Week 0 Week 2 Week 14 Time NALP3 expression 30 n= Week 0 Week 2 Week 14 Time Wilcoxon signed-rank test

15 Preliminary data suggest that infliximab also reduces NALP3 expression in the synovium NALP3 expression Non Responders (n=2) NALP3 mrna from synovial tissue biopsies pre- and post- infliximab treatment 0 Pre Post Responders (n=3) Mann-Whitney U test.

16 ASC mrna increased during infliximab treatment in responders Infliximab Responders 100 p=0.036 n=9 Infliximab non-responders n=10 ASC expression ASC expression Wk0 Wk Wk0 Wk2 Wk14 ASC Actin Wk14 Wk2 Wk0 Protein expression in one representative RA patient who responded to therapy Wk2 100

17 Summary baseline NALP3 a potential predictor of response to infliximab in RA patients - levels further reduced in those who respond to therapy ASC mrna levels are increased in patients responding to infliximab after week 14 of treatment Future work examine ASC and NALP3 mrna in synovial tissue determine the changes in different leukocyte populations

18 Different effects of infliximab and etanercept on ASC levels in PBMCs of RA patients Infliximab Etanercept ASC Pyrin mrna Protein mrna No change No change Variable Pronounced changes in ASC mrna and protein expression were observed in RA patients receiving infliximab, but not etanercept Protein No change Variable (EWRR 2007)

19

20 Mutations in genes encoding the RNASEH2 complex and TREX1 cause AGS TREX1 Ch. 3 AGS1 RNASEH2A Ch. 19 AGS4 RNASEH2B/FLJ11712 Ch. 13 AGS2 RNASEH2C/AYP1 Ch. 11 AGS3

21 Aicardi-Goutieres syndrome (AGS) and SLE Aicardi-Goutieres syndrome (AGS) is a genetic encephalopathy whose clinical features mimic acquired in utero viral infection. early-onset disease with calcification of basal-ganglia, white-matter abnormalities, and a chronic cerebrospinal fluid (CSF) lymphocytosis raised levels of antiviral cytokine interferon alpha (IFN-α) in the CSF nucleases defective in AGS (TREX1 and RNASEH2A, 2B and 2C) remove endogenous nucleic acids during normal cellular processes possibly act on a common substrate, and failure of nuclease activity results in an (inappropriate) activation of the innate immune system heterozygous missense changes and frameshift in 6/218 SLE patients (UK), 6/199 (Germany) compared with 0/200 and 2/1,512 in controls dual role of TREX1 as DNA-degrading enzyme in granzyme A mediated apoptosis and cytosolic DNA sensor induce autoimmunity when this nuclease is mutated

22 Self nucleic acids Virus ss/dsdna ssrna dsrna Endosomal nucleic acid sensing TLRs TLR9 TLR7(8) TLR3 RIG-1 DAI Inflammasome MDA5 Type I IFN induced antiviral state

23 Receptors of the innate immune system TLR2 TLR4 TLR5 Endosome Toll-like receptors (TLRs) TLR3 TLR7 TLR9 Nod-like receptors (NLRs) TLR8 MyD88 dependent/ independent pathways Intracellular pathogens endogenous signals Danger IKK NF-κB Caspase-1/ -5 NALPs NAIP5 IPAF Nod1/2 Proinflammatory cytokines IL-1β IL-18 Pro-IL-1β Pro-IL-18 Pathogen clearance

24 Role of TLRs in Lupus Nucleosomes (Host derived) TLR-9 DNA Protein ssrna TLR-7 MyD88 Plasmacytoid Dendritic cell IFN-α

25 TLRs as Therapeutic Targets: TLR-9 and Autoantibodies Nucleosomes (Host-derived) DNA Protein TLR-9 MyD88 Y Y Self IgG2a RF Autoreactive B cell Y Y Y Y Autoantibodies IgG2a = immunoglobulin G2a; RF = rheumatoid factor.

26 Expression of TLR2 mrna in RA synovial tissue anti-sense probe sense control probe INDUCTION OF CO-STIMULATORY MOLECULES CD80/86 INDUCTION OF TNF Courtesy of Steffen Gay and colleagues

27 Toll-like Receptors Microbial products Products of inflamed tissues 10 TLRs MyD88 Mal Trif Tram NLRs Modulation of immune and inflammatory genes Immune and inflammatory effector mechanisms

28 The Innate World as we Know it: Host Defence SENSOR SIGNAL RESPONSE ADAPTER M I C R O B E S TLRs NLRs RLRs NF-κB IRFs MAPKs Caspase-1 IRFs Cytokines and chemokines Anti-viral proteins proil-1 and proil-18 Mature IL-1 and IL18 Anti-viral proteins MyD88 Mal Trif Tram MyD88 MAVS/IPS-1/ VISA/Cardiff

29

30 Why is Autoimmunity paradigm so strong? Approx 1,000,000, 000 T cell receptors in man T cell clones expand x 64,000 in 4 days Each activated Th1 cell attracts up to 1,000 macrophages T cells stimulate macrophages to make IFN etc Repertoire- an almost unlimited number of epitopes Memory with secondary responses: occur sooner, steeper, faster, higher and with a lower lower threshold

31 Aicardi-Goutières syndrome (AGS)

32 Adaptive vs innate immunity in rheumatoid arthritis Rheumatoid arthritis (RA) has traditionally been described as an adaptive immune response, but, more recently, there has been a gradual appreciation of the role of the innate immune system The innate immune system recognises -microbial pathogen associated molecular patterns (PAMPs) -endogenous signals; danger associated molecular patterns (DAMPs) The detection of DAMPs and PAMPs is through Toll-like receptors (TLRs) and Nod-like receptors (NLRs)