Transplantation intro 204_2023 final.pptx

Transplantation Immunology BSMS Module 204 10 May 2023 Prof Florian Kern Chair in Immunology BSMS 1 Contents I. Nomenclature of transplantation and overview II. The immune response to the graft III.Preparing for a transplantation IV. Immunosuppression V. ‘Self’ versus ‘non-self’ VI.Limits of allo...

Transplantation Immunology BSMS Module 204 10 May 2023 Prof Florian Kern Chair in Immunology BSMS 1 Contents I. Nomenclature of transplantation and overview II. The immune response to the graft III.Preparing for a transplantation IV. Immunosuppression V. ‘Self’ versus ‘non-self’ VI.Limits of allo-transplantation Learning objectives are listed at the end 2 I. Nomenclature and overview Syngeneic • Syngeneic: same genetic background 3 I. Nomenclature and overview Syngeneic All og en eic • Syngeneic: same genetic background • Allogeneic: same species, different genetic background 4 I. Nomenclature and overview • Syngeneic: same genetic background • Allogeneic: same species, different genetic background • Autologous: identical individual 5 I. Nomenclature and overview • Isograft - to a genetically identical individual (homozygos twins) (iso/syngeneic) • Allograft - to a genetically disparate member of the same species (allogeneic) • Autograft - to another site on the same individual (e.g. after a burn) (autologous) • Xenograft - to a different species (pig o monkey to human) (xenogeneic) 6 I. Nomenclature and overview • Interruption of donor organ blood supply • Removal or donor organ • Perfusion with cold preservation solution • Placement of donor organ in recipient • Reconnection of blood supply to the graft warm ischemic time cold ischemic time warm ischemic time • Reperfusion of the graft 7 I. Nomenclature and overview • Warm ischemic time (very harmful) – from the interruption of circulation to the donor organ to the moment when organ is flushed with hypothermic preservation solution. – from the moment the organ is removed from the cold preservation solution until the time that blood supply is reinstated. • Cold ischemic time (somewhat less harmful) – from the moment the organ is flushed with cold preservation solution until its removal from that solution. 8 I. Nomenclature and overview • Cadaveric donor transplant – the transplant is from a recently deceased donor – Examples: heart, lung, pancreas, liver, kidney, cornea, limbs • Live-donor transplant: – The donor is alive and related (frequent) or unrelated (less frequent) – Examples: kidney, liver segments 9 I. Nomenclature and overview • MHC-complex = Major histocompatibility complex – HLA is the human MHC (= Human leukocyte antigen) – These are molecules involved in antigen-presentation to T-cells and draw antibody responses • HLA-alleles are the allelic variations of HLA-molecules (e.g. HLA-B*07:01 and HLA-B*07:02) • Remember that the HLA-complex increases diversity and so improves survival of the species (we cannot rapidly mutate like bacteria or viruses) • It is that very diversity which makes transplantation difficult • ‚Non-self‘ refers to HLA-molecules/alleles not expressed by 10 I. Nomenclature and overview No MHC extracellular MHC-I (A,B,C) MHC-II (DRB1, DPB1, DQB1 presented extracellular intracellular intracellular II. The immune response to the graft II. The immune response to the graft Example: Kidney Graft How damage is caused by the OP Diseased Kidneys • Wound healing means inflammation Ureter • Warm ischemic time & cold Iliac Vein ischemic time induce heatshock protein expression and Iliac Artery other stress-induced Kidney graft molecules • Reperfusion of ischemic organ Ureter graft causes reperfusion damage as Bladder a result of endothelial 13 II. The immune response to the graft Virus/other antigen B-cells Macrophage or DC Graft cell MHC II (non-self) MHC I (non-self) CD4 T-cell CD8 T-cell Plasma cells CTL Memory B-cell Memory CD4 T-cell Memory CTL Killed target 14 II. The immune response to the graft: antiHLA antibodies 15 II. The immune response to the graft: antiHLA antibodies Activated endothelium Antibody legend: Same colour Fc region = same subclass CD Different colours of 4 F(ab) region = unique antigenic specificities Anti class-I MHC antibodies can induce changes in the donor vasculature, for example, causing endothelial cell (EC) activation 16 with class-II MHC expression, and, as a result, CD4 T cell proliferation. II. The immune response to the graft: antiHLA antibodies C4 d C1 q Complement-activating antibodies trigger the classical pathway through binding of C1q, resulting in production of the anaphylatoxins C3a and C5a, which have the potential to directly augment leukocyte 17 II. The immune response to the graft: antiHLA antibodies Monocytes, neutrophils, and natural killer (NK) cells also express Fc receptors (FcγRs), which can interact with the heavy chain of HLA antibodies bound to donor ECs. The FcγR functions augment leukocyte 18 recruitment and mediate phagocytosis and antibody-dependent II. The immune response to the graft: antiHLA antibodies Activated ECs express P-selectin, which promotes recruitment of leukocytes via interactions with P-selectin glycoprotein ligand-1 (PSGL-1). Recruited monocytes differentiate into CD68+ macrophages, 19 II. The immune response to the graft: antiHLA antibodies We conclude that anti-HLA Antibodies can severely damage the graft. There are also antibodies to a range of other antigens including: • Red Blood Cell (RBC) antigens (mainly ABO system) • Endothelial Cell Antigens Anti-RBC and anti-EC antibodies can also induce significant graft damage. 20 II. The immune response to the graft: hyperacute rejection • Very early destruction of the graft (minutes/hours/days) caused by antibodies to HLA, RBC, and EC antigens • It is called hyperacute rejection. • It can be prevented partially by matching donor and recipient HLA-types and blood groups. • There is no known way of avoiding the Small artery mostly occluded effect of anti-EC antibodies as these are by a fibrin thrombus in thought to recognise damaged EC and hyperactute rejection are not donor-specific (‘matching’ is not possible). II. The immune response to the graft: CD4 T-cells Virus/other antigen B-cells Macrophage or DC Graft cell MHC II (non-self) MHC I (non-self) CD4 T-cell CD8 T-cell Plasma cells CTL Memory B-cell Memory CD4 T-cell Memory CTL Killed target 22 II. The immune response to the graft: CD8 T-cells Virus/other antigen B-cells Macrophage or DC Graft cell MHC II (non-self) MHC I (non-self) CD4 T-cell CD8 T-cell Plasma cells CTL Memory B-cell Memory CD4 T-cell Memory CTL Killed target 23 II. The immune response to the graft: Tcells T-cell TCR Nonself MHC II Non-self APC TCR interaction with a non-self class-II HLA/peptide complex is often very strong and dominated by TCR/MHC interactions. • Donor APCs come with the graft as ‚passenger‘ cells. • Also, extracellular vesicles (EVs) from stressed graft cells are thought to transport donor HLA molecules into recipient APCs, allowing effective expression of donor HLA-molecules. • This may lead to strong recipient T-cell activation requiring strong immunosuppression. • The survival time of passenger APC is limited 24 so that immunosuppression can be reduced II. The immune response to the graft: Tcells Polymorphic self proteins that differ in amino acid sequence between individuals give rise to minor histocompatibility antigen differences between donor and recipient. 25 II. The immune response to the graft: Tcells 26 II. The immune response to the graft: ‘acute rejection’ Rejection of the graft that is mainly mediated by T-cells and occurs within weeks to months is called ACUTE REJECTION • It can be reduced/prevented by HLA-matching of donor and recipient. • Antibodies developing against the donor HLA after transplantation can also make a contribution to acute rejection. 27 II. The immune response to the graft: 'Chronic rejection’ Chronic vascular damage – a combination of effects Antibodies to HLA & endothelial cell antigens entertain proinflammatory cytokine production and inflammation Media proliferation & thickening of vascular wall Reduction of vascular lumen Reduced blood supply with hypoxia, stress response, etc. 28 II. The immune response to the graft: 'Chronic rejection’ Duration of ischaemic time Less damage More damage Immunogenicity & incidence of chronic rejection increase with increasing ischaemic time 29 II. The immune response to the graft: Mechanisms of graft damage Type Mechanism Hyperacute rejection Preformed antibody Acute rejection T-cells, anti-HLAantibodies formed in response to the graft Chronic Rejection Chronic processes, antibodies to major and minor histocompatibility antigens Time-line Minutes/hours/days Weeks, months, even longer (‘late acute rejection’) Months to many years 30 III. Preparing for a transplantation 31 III. Preparing for a transplantation: HLAmatch HLA-matching – minimum requirements depend on the situation • A kidney transplant, for example, can wait a heart transplant is more urgent (artifical hearts can be used temporarily) • Generally, the better the match, the better the outcome • Liver transplants are generally not matched as they induce chimerism, i.e. the parallel existence of two mutually tolerant immune systems (chimerism is the result of immune cells from the donor settling in the recipient‘s bone marrow and supports graft acceptance) 32 III. Preparing for a transplantation: HLAmatch HLA-matching For solid organ transplantation, traditionally A,B, and DR are considered, the maximum is 6 mismatches (3 molecules inherited from each parent in both donor and recipient). Alleles are usually not considered in kidney transplantation (i.e HLA-B*07:01 and HLA-B*07:02 are both HLA-B*07). Bad match Good match HLA-Locus HLAA* HLA-B* HLADRB1* HLA-Locus HLAA* HLA-B* HLADRB1* Donor 1 02; 24 07; 08 04; 03 Donor 1 02; 24 07; 08 04; 03 Recipient 1 02; 01 27; 64 11; 15 Recipient 2 03; 24 07; 08 04; 03 2 2 Mismatches 1 0 0 Mismatches 1 33 III. Preparing for a transplantation: Crossmatching Donor/recipient cross matching = Incubation of washed donor cells with recipient serum. A test for pre-formed antibodies in the recipient directed against the donor. Antibody binding to donor leukocyte antigens may be detected in a variety of ways. This is an essential part of the preparation. This test will generally avoid hyperacute rejection.34 III. Preparing for a transplantation: AB0 matching In organ transplantation the same ABO rules apply as with blood transfusion – the donor organ is similar to a red blood cell that could be lysed if there are antibodies to its surface antigens ABO incompatibility is a major concern. Rhesus incompatibility is less of a worry and usually taken care of by sufficient 35 immunosuppression. IV. Immunosuppression IV. Immunosuppression: overview Activation signals represent interesting target molecules for immunosuppressio 37 IV. Immunosuppression: signal 1 Activation signals represent interesting target molecules for immunosuppressio Cyclosporin A anti CD3 38 IV. Immunosuppression: signal 2 Activation signals represent interesting target molecules for immunosuppressio CTLA-4IgG AntiCD154 39 IV. Immunosuppression: signal 3 Activation signals represent interesting target molecules for immunosuppressio Sirolimus Everolim us Azathiopri ne 40 IV. Immunosuppression: other Activation signals represent interesting target molecules for immunosuppressio Glucocorticoi ds Leflunomide 41 IV. Immunosuppression: biologicals Biologicals are probably the future (there are hundreds, some used in renal transplantation are highlighted) • visilizumab (Nuvion) • alemtuzumab (anti-CD52) • eculizumab (anti-C5, • natalizumab (Tysabri) Soliris) • rituximab (anti-CD20, • adalimumab (Humira) Rituxan) • anakinra (Kineret) • secukinumab (Cosentyx) • certolizumab (Cimzia) • tocilizumab (Actemra) • etanercept (Enbrel) • vedolizumab (Entyvio) • golimumab (Simponi) • basiliximab (anti-IL2, Simulect) • infliximab (Remicade) 42 IV. Immunosuppression: classic triple regimen in renal transplantation Calcineurin inhibition • Cyclosporin A, Tacrolimus • Inhibition of cytokine synthesis: IL-2, IFNg ... Anti-proliferative • Azathioprine, MMF • Inhibition of clonal expansions Anti-inflammatory • Corticosteroids • NFkb inhibition, cytokine synthesis and action 43 IV. Immunosuppression: preventing 'Chronic rejection’ Duration of ischaemic time Less damage Corticosteroids achieve inhibition/reduction of • Ischaemia/reperfusion injury • APC activation • Cytokine synthesis (acute inflammation) More damage 44 IV. Immunosuppression: situations where immunosuppression can be or should be reduced high risk of infection immuno-suppression risk of rejection low 45 V. ‘Self’ versus ‘non-self’ Traditional view: The immune system differentiates between ‘self‘ and ‘non-self‘ Alternative view : The immune system discriminates between ‘dangerous‘ and ‘not dangerous‘ 46 V. ‘Self’ versus ‘non-self’ Cytokines Tissue injury TNF, IL-1 ... Hypoxia ... danger signals Microbial products LPS, LTA, CpG DNA ... CytokineRs TLRs RLRs, NLRs TLRs APC Surgery provides danger signals: trauma, inflammation, ischemia/reperfusion, etc. 47 Prolonged warm ischaemic time reduces long-term graft survival (more V. ‘Self’ versus ‘non-self’ 48 VI. Limits of allo-transplantation Lung, Hear, Heart/Lung (cadaveric donor) HLA match: useful, but often not possible Complications: frequent Liver (cadaveric or living donor) HLA match: NO Complications: frequent Limbs and more (arm, leg, penis, womb) (cadaveric) HLA matching: YES Complications: yes, rates not known yet Kidney, Pancreas, Pancreas/Kidney (cadaveric donor) HLA match: YES Complications: frequent Uterus, Ovaries (cadaveric) HLA matching: YES Complications: not known yet Kidney (cadaveric or living donor) HLA matching: YES Complications: less frequent Bone Marrow/stem cells (living donor) Usually autograft, rarely allogeneic 49 HLA matching: essential Thank you! Questions to [email protected] 50 Learning outcomes You should be able to • Apply the basic nomenclature in relation to different graft types by donor/recipient relatedness • Understand the main principles of matching transplant donors and recipients (AB0, MHC), including cross-match and understand exceptions in donor/recipient matching • Describe the types, time-lines and mechanisms of graft rejection (hyperacute, acute, chronic) • Explain different types of immunosuppressive drugs used after transplantation, explain why drugs with different mechanism of action are used in parallel and be able to describe their principle effects. Be able to name at least one drug for each principle effect (e.g. Tacrolimus -> calcineurin inhibition). 51 Concepts to review • Transplantation/transfusion • Autologous/autograft,syngeneic/isograft, allogenic/allograft, xenogenic/xenograft • Cadaveric versus living donor • Warm /cold ischaemic time • AB0 matching, HLA matching, • cross matching, minor/major HLA mismatch, AB0 mismatch, • Hyperacute rejection, acute rejection, chronic rejection • Immunosuppressive therapy • Transplantation trauma caused by ischemia/operation 52 53 54 VCA transplantation – vascularised composite allografts e.g. replacement of hands Complex micro-surgical procedures involving skin, vasculature, nerves, bone…. Surprising functional results Protocols often commence with antibody based induction therapy including anti-thymocyte globulin, or, anti-IL2 (daclizumab, basiliximab) anti CD3 (OKT3), anti CD52 (campath-1H, alemtuzumab) Please check out these drugs! 55