移植免疫课程班201612ppt课件

移植免疫 Transplantation Immunology,器官移植简史和概念 同种异体器官移植排斥的机制 移植排斥反应的类型 同种异体器官移植排斥反应的防治原理 诱导同种移植耐受的基本策略 移植相关的免疫学问题,同种异体器官移植简史 移植的基本概念 同种异体器官移植在临床中的应用 移植物来源的分类 移植排斥反应的影响因素,器官移植简史和概念, Alexis Carrel reported the first systematic study of transplantation in 1908; he interchanged both kidneys in a series of nine cats. Some of those receiving kidneys from other cats maintained urinary output for up to 25 days. Although all the cats eventually died. The first human kidney transplant, attempted in 1935 by a Russian surgeon, failed because there was a mismatch of blood types between donor and recipient. The first successful human kidney transplant, which was between identical twins, was accomplished in Boston in 1954., Today , kidney, pancreas, heart, lung, liver, bone-marrow, and cornea transplantations are performed among nonidentical individuals with ever-increasing frequency and success.,同种异体器官移植简史,移植的基本概念 应用自体或异体的正常细胞、组织或器官，置换病变或功能缺损的细胞、组织或器官，以维持和重建机体的生理功能，这种治疗方法称为细胞移植、组织移植和器官移植。 移植排斥反应是移植物（细胞、组织或器官）抗原可刺激受者的免疫系统从而诱发免疫应答（宿主抗移植物反应）;受者组织抗原也可能刺激移植物中的免疫细胞从而诱发免疫应答（移植物抗宿主反应）。 根据移植物移植的部位不同，可分同位或正位移植及异位移植，即前者是将组织或器官移植至该宿主组织或器官的正常解剖部位，后者是将组织或器官移植该宿主并非其原先的解剖部位。 *供者 提供移植物的个体；受者(宿主) 接受移植物的个体。,同种异体器官移植在临床中的应用,异种移植的实验研究,猪人异种移植,人畜共患病 (xenozoonosis),异种移植存在的问题,异种移植排斥反应比同种移植更强烈、机制更复杂 异种移植排斥对免疫抑制药物不敏感 畜类微生物感染对人类的潜在威胁 异种器官与人类宿主的生理学不相容性 异种移植研究的动物模型有待建立和完善,同种异体器官移植一般均会发生排斥反应，排斥反应的强弱取决于: 供受体间组织相容性抗原的差异程度; 受者的免疫状态; 移植物种类; 防治措施。,移植排斥反应的影响因素,一、引起同种异体移植排斥反应的抗原 二、T细胞识别同种抗原的机制 三、移植排斥反应的效应机制,同种异体器官移植排斥的机制,1.主要组织相容性抗原 2.次要组织相容性抗原 3.其他参与排斥反应发生的抗原,一、引起同种异体移植排斥反应的抗原,The genetics of graft rejection. In the illustration, the two different mouse colors represent inbred strains with different MHC haplotypes. Inherited MHC alleles from both parents are codominantly expressed in the skin of an A B offspring, and therefore these mice are represented by both colors. Syngeneic grafts are not rejected (A). Allografts are always rejected (B). Grafts from an A or B parent will not be rejected by an (A B)F1 offspring (C), but grafts from the offspring will be rejected by either parent (D). These phenomena are due to the fact that MHC gene products are responsible for graft rejection; grafts are rejected only if they express an MHC type (represented by green or orange) that is not expressed by the recipient mouse.,主要组织相容性抗原,能引起强烈排斥反应的移植抗原称为主要组织相容性抗原(MHC抗原)，在人类最重要者为HLA抗原。本质上，供、受者间HLA型别差异是发生急性移植排斥反应的主要原因。,次要组织相容性抗原,次要组织相容性抗原(minor histocompatibility antigen, mH antigen)表达于机体组织细胞表面，由某些具有多态性的基因编码，可被MHC分子提呈，主要包括两类：,1.性别相关的mH抗原 2.常染色体编码的mH抗原,Minor H antigens are peptides derived from polymorphic cellular proteins bound to MHC class I molecules. Self proteins are routinely digested by proteasomes within the Cells cytosol, and peptides derived from them are delivered to the endoplasmic reticulum, where they can bind to MHC class I molecules and be delivered to the cell surface. If a polymorphic protein differs between the graft donor (shown in red on the left) and the recipient (shown in blue on the right), it can give rise to an antigenic peptide (red on the donor cell) that can be recognized by the recipients T cells as nonself and elicit an immune response. Such antigens are the minor H antigens.,This chart gives the rejection times for skin grafts between mice differing at the major histocompatibility H-2 locus (blue). Grafts which differ at multiple minor loci are rejected as quickly as those that differ at H-2.,Mouse histocompatibility antigens and graft survival,mH抗原诱导同种异型排斥反应的特点：mH抗原以MHC限制性方式被CTL和Th细胞识别；不同类型mH抗原可被不同型别HLA分子提呈；不同mH抗原分子结构不同，其与特定MHC分子结合的亲和力亦各异，故在不同供、受者间进行移植，参与排斥反应的和占优势的mH抗原种类可能不同；供-受者间单个mH抗原不相同，一般引起缓慢的排斥反应; 多个mH抗原不相符,可引起类似于MHC不相符所致的快速排斥反应。,其他参与排斥反应发生的抗原,人类ABO血型抗原:ABO血型抗原不仅分布于红细胞表面，也表达于肝、肾等组织细胞和血管内皮细胞表面。 组织特异性抗原:指特异性表达于某一器官、组织或细胞表面的抗原，如血管内皮细胞 (VEC) 抗原；皮肤 (SK) 抗原。,ABO blood group antigens. A, Blood group antigens are carbohydrate structures added onto cell surface proteins or lipids by the action of glycosyltransferases (see text). B. Different blood group antigens are produced by the addition of different sugars by different inherited glycosyltransferase. Individuals who express a particular blood group antigen are tolerant to that antigen but produce antibodies that react with other blood group antigens.,1.T细胞在移植排斥反应中作用,二、T细胞识别同种抗原的机制,先天性无胸腺的啮齿类动物 (如裸鼠) 体内无成熟T细胞，不能排斥移植物；新生儿期摘除正常大鼠或小鼠的胸腺，会发生同样情况；上述情况中，若注射同系正常小鼠T细胞，则小鼠即可对移植物产生排斥反应。,2.T细胞对移植物抗原的特异性识别 直接识别(direct recognition)的特点和机制 间接识别(indirect recognition)的特点和机制,First- and second-set allograft rejection. Results of the experiments shown indicate that graft rejection displays the features of adaptive immune responses, namely, memory and mediation by lymphocytes. An inbred strain B mouse will reject a graft from an inbred strain A mouse with first-set kinetics (left panel). An inbred strain B mouse sensitized by a previous graft from an inbred strain A mouse will reject a second graft from an inbred strain A mouse with second-set kinetics (middle panel), demonstrating memory. An inbred strain B mouse injected with lymphocytes from another strain B mouse that has rejected a graft from a strain A mouse will reject a graft from a strain A mouse with second set kinetics (right panel), demonstrating the role of lymphocytes in mediating rejection and memory. An inbred strain B mouse sensitized by a previous graft from a strain A mouse will reject a graft from a third unrelated strain with first-set kinetics, thus demonstrating another feature of adaptive immunity, specificity (not shown). Syngeneic grafts are never rejected (not shown).,T细胞在移植排斥反应中作用,参见图19-2,同种异体间的器官移植一般均会发生排斥反应，本质上乃受者免疫系统对供者移植物抗原的免疫应答。,Presentation of allograft antigens,1. A high density of graft MHC molecules, which individually react weakly with the TCR may generate a sufficient signal for T cell activation. 2. Graft MHC molecules can present the grafts own peptides including molecules from both major and minor histocompatibility antigens. 3. Graft MHC molecules can present processed antigens of host molecules. 4. Allotypically different graft molecules, including histocompatibility antigens can be taken up by host antigen presenting cells, and be processed and presented on self MHC molecules.,T细胞对移植物抗原的特异性识别,受者T细胞可通过直接识别、间接识别和半直接途径识别同种异型抗原,受者T细胞对同种异型抗原的识别途径 A: 直接识别：受者同种反应性T细胞的TCR直接识别供者APC所提呈的供者MHC分子或外源肽-供者MHC复合物； B. 间接识别：受者同种反应性T细胞的TCR识别经受者APC加工处理的供者MHC抗原肽； C：半直接识别: 受者同种反应性CD8+T细胞循直接途径识别供者APC所提呈的同种MHCI类分子；受者同种反应性CD4+T细胞循间接途径识别经受者APC加工、处理和提呈的同种异型MHC分子，并协助CD8+T细胞分化。,直接识别的特点 速度快，因为无须经历抗原摄取、处理和加工； 强度大，因为每一个体中，具有同种抗原反应 性的T细胞克隆约占T细胞库总数的1%10%， 而针对一般异源性抗原的T细胞克隆仅占总数的 1/100001/100000。直接识别在早期急性排斥反 应中起重要作用。 直接识别的机制 TCR乃识别抗原肽和MHC分子的复合结构(pMHC)的特点 记忆T细胞是参与交叉反应的主要效应细胞,受者同种反应性T细胞交叉识别pMHC 具有相同或相似复合结构的不同抗原肽-MHC分子可被同一受者TCR所识别:（A）正常免疫应答过程中，受者TCR特异性识别外来抗原肽-自身MHC分子所形成的复合结构；（B）同种异体移植时，受者同一TCR可识别单一（空载）的供者MHC分子；（C）同种异体移植时，受者同一TCR可识别供者自身肽-供者MHC分子复合物。,TCR乃识别抗原肽和MHC分子的复合结构(pMHC),TCR的CDR3识别抗原肽；CDR1和CDR2识别MHC分子螺旋的保守序列。 特异性TCR乃识别pMHC在结合界面所形成的复合结构； TCR对pMHC的识别具有简并性，即同一TCR可能识别不同的pMHC； CDR3的构型具有包容性，可通过构型改变而识别不同pMHC。,某些情况下，受者同种反应性T细胞还可直接识别供者MHC分子，而与后者是否结合抗原肽无关 (抗原肽的存在仅起稳定MHC分子的作用)，此现象称为MHC分子优势结合 (MHC-dominant binding)。其机制是：虽然供者MHC分子结构与受者特异性TCR缺乏严格的空间构象互补性，即与受者TCR结合的亲和力低，但由于其高表达于供者APC (及移植物组织细胞) 表面，仍可激活受者多克隆T细胞。,TCR识别pMHC特点,实验研究表明：参与初次移植排斥的同种反应性T细胞中，包括体内预存的某些记忆T细胞克隆（具有记忆细胞的表型）。可能与隐性、显性微生物感染或接触的外源性抗原各异有关。,记忆T细胞是参与交叉反应的主要效应细胞,The Journal of Immunology, 2006, 176:26912696,在急性排斥反应早期，间接识别与直接识别机制协同发挥作用；在急性排斥反应中晚期和慢性排斥反应中，间接识别机制起更为重要的作用。,间接识别的特点和机制,半间接识别(图19-3),1.急性排斥反应的细胞免疫效应机制 2.同种移植急性排斥反应的体液免疫效应机制 3.参与同种移植急性排斥反应损伤机制的其他 细胞与组织成分 4.参与移植排斥反应的非特异性效应机制,三、移植排斥反应的效应机制,perforin and granzyme,IFN-、IL-2、 IL-17,IL-1、IL-6、IL-8、TNF-,急性排斥反应的细胞免疫效应机制,同种移植急性排斥反应的体液免疫效应机制,Effector mechanisms of antibody-mediated disease. A. Antibodies opsonize cells and may activate complement, generating complement products that also opsonize cells, leading to phagocytosis of the cells through phagocyte Fc receptors or C3 receptors B. Antibodies recruit leukocytes by binding to Fc receptors or by activating complement and thereby releasing by-products that are chemotactic for leukocytes.,参与同种移植急性排斥反应损伤机制的其他细胞与组织成分,Transplanted organ,肾脏,参与移植排斥反应的非特异性效应机制,非特异性效应分子 固有免疫效应细胞 DAMP和促炎介质(炎性细胞因子/趋化因子等) DC、NK、NKT、M和中性粒细胞等,移植排斥反应的类型,一、宿主抗移植物反应 二、移植物抗宿主反应 三、排斥反应的特殊情况,一、宿主抗移植物反应 (HVGR),HVGR乃宿主免疫系统对移植物发动攻击，导致移植物被排斥。各类器官移植排斥反应的免疫学效应机制基本相同，根据排斥反应发生的时间、强度、机制和病理表现，大致可分为超急性排斥、急性排斥、慢性排斥反应三类。,1.超急性排斥反应 (hyperacute rejection) 2.急性排斥反应 (acute rejection) 3.慢性排斥反应 (chronic rejection),Histopathology of different forms of graft rejection. A, Hyperacute rejection of a kidney allograft with endothelial damage, platelet and thrombin thrombi, and early neutrophil infiltration in a glomerulus. B, Acute rejection of a kidney with inflammatory cells in the connective tissue around the tubules and between epithelial cells of the tubules. C, Acute antibody-mediated rejection of a kidney allograft with destructive inflammatory reaction destroying the endothelial layer of an artery. D, Complement C4d deposition in vessels in acute antibody-mediated rejection. E, Chronic rejection in a kidney allograft with graft arteriosclerosis. The vascular lumen is replaced by an accumulation of smooth muscle cells and connective tissue in the vessel intima. (Courtesy of Dr. Helmut Rennke, Department of Pathology, Brigham and Womens Hospital and Harvard Medical School, Boston, Massachusetts.),Steps in the hyperacute rejection of a kidney graft,超急性排斥反应,Effector mechanisms involved in allograft rejection (effector stage),Antigen-reactive lymphocytes of the recipient proliferate in response to alloantigens on the graft (sensitization phase).,急性排斥反应,机体针对同种抗原的免疫应答（移植排斥）发生于外周免疫器官,Immunological mechanisms of chronic transplant rejection,慢性排斥反应,1.参与慢性排斥反应的危险因素 （代谢紊乱、药物毒性和感染） 2.适应性免疫介导 （急性排斥反复发作，感染诱导）,HMGB1通过启动RAGE相关的信号通路促进TGF-释放； HMGB1诱导某些整合素家族分子表达, 促进TGF-转化为活性形式； TGF-刺激多种细胞（如内皮细胞、平滑肌细胞、成纤维细胞等）产生反应性氧中介物（ROS），进而主动释放HMGB1； TGF-诱导巨噬细胞核内HMGB1转位至胞浆，并促进HMGB1合成和主动分泌。,HMGB1/TGF-反应环参与心脏移植物血管病变(CAV) 发生的机制,高速泳动族框蛋白I（HMGB1）是重要的DAMP，在介导移植物损伤中发挥关键作用；TGF-是参与移植物组织过度修复的关键因子，可通过启动Smad3信号途径而诱导平滑肌细胞、成纤维细胞、内皮细胞增殖，并促进I型胶原、型胶原等多种细胞外基质合成及分泌，从而参与和促进移植物组织慢性修复。,3.固有免疫与慢性排斥反应,二、移植物抗宿主反应（GVHR）,Graft-versus-host reactions（GVHR）,GVHR是由移植物中抗原特异性淋巴细胞识别宿主组织抗原所致的排斥反应，发生后一般均难以逆转，不仅导致移植失败，还可能威胁受者生命。GVHR的发生依赖于下列条件： 受者与供者间HLA型别不符； 移植物中含有足够数量免疫细胞，尤其是成熟的T细胞； 移植受者处于免疫无能或免疫功能极度低下的状态 (被抑制或免疫缺陷)。,三、排斥反应的特殊情况, 机体某些解剖部位易于接受同种乃至异种组织器官移植，而不发生或仅发生轻微排斥反应。这些部位称为免疫赦免区 (immunologically privileged site)，包括角膜、眼前房、软骨、脑、胎盘滋养层、某些内分泌腺等。机制可能为： 这些部位 (如角膜) 缺少输入血管和淋巴管，故血循环中的淋巴细胞难以到达赦免区局部，亦不能接触移植物抗原，从而不易发生免疫排斥反应； 体内存在特殊的屏障，如血-脑屏障能阻止抗体和免疫活性细胞进入脑组织与之接触，故脑内组织移植易于成功； 某些组织，如软骨组织的免疫原性较弱，故软骨移植一般不易引起排斥反应； 某些(如母胎屏障）免疫赦免区组织细胞高表达免疫抑制分子如FasL、HLA-G、IDO等，微环境中存在免疫抑制性细胞。,Juch et al. Placenta and HLA. 9-10/2012,Key pathways involved in immune tolerance toward the fetus during the first trimester of human pregnancy. Anchoring villous trophoblasts attach to the decidua and further differentiate into syncytiotrophoblasts, cytotrophoblasts and EVTs. Floating villous trophoblasts carrying fetal blood vessels are bathed in maternal blood and can shed placental exosomes, microparticles and fetal stem cells. Expression of chemokine receptors and their cognate ligands orchestestrate the iinvasion of EVTs and migration of maternal leukocytes into the decidua. EVTs establish direct contact with DSCs and maternal leukocyte populations. Via IL-15 and stem cell factor (SCF) production by DSCs, denovo generation of dNK cells occurs locally upon differentiation of tissue resident linnegCD45+CD34+ decidual hematopoetic stem cells (dHSCs). Macrophage inhibitory cytokine-1 (MIC-1), TGF-1 and galectin-1 production by DSCs and/or NK cells promotes the arrest of decidual DCs in a tolerogenic state (tDCs), and NK cellderived galectin-1 induces apoptosis of activated T cells in vitro . Upon dNK cellderived IFN- secretion, the enzymatic expression of IDO in human decidual CD14+ monocytes, another predominant decidual cell subset of the innate immune system, is upregulated in vitro. Monocyte-derived IDO may enhance fetal tolerance via the generation of CD4+ Treg cells or selective apoptosis of effector T cells 122 . Synergistically with tDCs and monocytes, dNK cells promote the generation of Treg cells and apoptosis of effector T cells. Decidualization is modulated by pregnancy hormones such as progesterone. The anatomical position where these maternal daptations occur is indicated by the white square in the insert of a pregnant uterus.,移植排斥反应的防治原理,一、供者的选择 二、移植物和受者的预处理 三、抑制受者的免疫应答 四、移植后的免疫监测,一、供者的选择,1.红细胞血型检查 2.受者血清中细胞毒性预存HLA抗体测定 3.HLA分型 4.交叉配型 5.次要组织相容性抗原型别鉴定,Influence of MHC matching on graft survival. Matching of MHC alleles between the donor and recipient significantly improves renal allograft survival. The data shown are for deceased donor (cadaver) grafts. HLA matching has less of an impact on survival of renal allografts from live donors, and some MHC alleles are more important than others in determining outcome. (Data from Organ Procurement and Transplantation Network/Scientific Registry annual report, 2010.),二、移植物和受者的预处理,1.移植物预处理 实质脏器移植时，尽可能清除移植物中过路细胞有助于减轻或防止HVGD发生。 2.受者预处理 实质脏器移植中，供、受者间ABO血型物质不符可能导致强的移植排斥反应。术前给受者输注供者特异性血小板；借助血浆置换术去除受者体内天然抗A或抗B凝集素；受者脾切除；免疫抑制疗法等。,三、抑制受者的免疫应答,1.免疫抑制药物的应用 化学类免疫抑制药 生物制剂 中草药类免疫抑制剂 2.清除预存抗体 3.其他免疫抑制方法,Mechanism of action of immunosuppresive drugs. Each major category of drugs used to prevent or to treat allograft rejection is shown along with the molecular targets of the drugs.,Production of IL-4 is defective in the non-obese (NODmouse (1) and diabetes-prone BB rat (2); the disease can be corrected by injection of the cytokine. The same is true for the production of TNFa by the NZBxW lupus mouse (3). Rheumatoid arthritis patients have a poor hypothalamie response to IL-1 and IL-6(4). The hypothalamic-pituitary axis is defective in the Obese strain chicken and in the Lewis rat which is prone to the development of Freunds adjuvant mediated experimental autoimmune disease (5). CRH = corticotrophin releasing hormone; M =macrophage.,糖皮质激素（glucocorticoids）,Anti-inflammatory effects of corticosteroid therapy. Corticosteroids regulate the expression of many genes, with a net anti-inflammatory effect. First, they reduce the production of inflammatory mediators, including cytokines, prostaglandins, and nitric oxide (NO). Second, they inhibit inflammatory cell migration to sites of inflammation by inhibiting the expression of adhesion molecules. Third, corticosteroids promote the death by apoptosis of leukocytes and lymphocytes. The layers of complexity are illustrated by the actions of annexin-1(originally identified as a factor induced by corticosteroids and named lipocortin), which has now been shown to participate in all of the effects of corticosteroids listed on the right. NOS, NO synthase.,Rapamycin inhibits cell growth and proliferation by selectively blocking activation of the kinase mTOR by RAPTOR. Rapamycin(sirolimus) binds FK-binding protein (FKBP), the same immunophilin protein that binds to tacrolimus (FK506). The rapamycin:FKBP complex does not inhibit calcineurin, but instead blocks one of the two pathways that activate mTOR(mammalian target of rapamycin), a large kinase that regulates many metabolic pathways. mTOR can be activated by association with two proteins, RAPTOR (regulatory associated protein of mTOR) and RICTOR (rapamycin-insensitive companion of mTOR). RAPTOR, which is activated by the Ras/MAPK pathway, promotes cell proliferation, translation of proteins, and autophagy. RICTOR, which is activated downstream of PI 3-kinase, influences cell adhesion and migration by controlling the actin cytoskeleton. The rapamycin:FKBP complex acts to inhibit only the RAPTOR-mediated activation of mTOR, and thereby selectively reduces cell growth and proliferation.,Cyclosporin A and tacrolimus inhibit T-cell activation by interfering with the serine/threonine-specific phosphatase calcineurin. As shown in the upper panel, signaling via T-cell receptor-associated tyrosine kinases leads to ope