黏膜免疫研究生.ppt

黏膜免疫 Mucosal Immune,黏膜免疫系统（mucosal immune system）： 直接接触病原体的解剖部位并能够分泌粘液的上皮细胞所覆盖，构成黏膜免疫系统。 广泛分布于呼吸道、胃肠道、泌尿生殖道黏膜下及一些外分泌腺体（唾液腺、泪腺、乳腺）处的淋巴组织。 执行局部特异性免疫功能的主要场所。,The mucosal immune system. The tissues of the mucosal immune system are the lymphoid organs associated with the intestine, respiratory tract, and urogenital tract, as well as the oral cavity and pharynx and the glands associated with these tissues, such as the salivary glands and lachrymal glands. The lactating breast is also part of the mucosal immune system.,黏膜免疫系统亦称黏膜相关淋巴组织（mucosa-associated lymphoid tissue, MALT）。,黏膜免疫系统与免疫应答 黏膜免疫系统中的固有免疫应答 黏膜免疫系统中的适应性免疫应答 黏膜免疫中的免疫耐受和免疫调节 黏膜免疫与疾病,主要内容,小肠黏膜免疫系统的各种细胞成分和器官化的淋巴组织,Cross-sectional diagram of the mucous membrane lining the intestine showing a nodule of lymphoid follicles that constitutes a Peyers patch in the submucosa. The intestinal lamina propria contains loose clusters of lymphoid cells and diffuse follicles.,黏膜免疫系统与免疫应答 （结构和应答特点）,黏膜免疫系统的特点,解剖特征 粘膜上皮和淋巴组织间因相互作用而联系紧密。 由散在的淋巴组织和器官化的结构（如派氏集合淋巴结、 分立的淋巴滤泡和扁桃体）共同组成。 启用抗原摄取机制，如出现派氏集合淋巴结和M细胞。 效应机制 在无感染发生的情况下拥有大量活化的T细胞和记忆细胞。 存在非特异性激活的“天然”效应性T细胞和记忆性T细胞。 大量启用分泌型IgA抗体。 涉及各种共生微生物菌丛。 免疫调节 可主动下调针对食物和其它共生性抗原的强势免疫应答。 可激活抑制性巨噬细胞及诱导耐受的树突状细胞。,*黏膜覆盖面大；肠腔中充满各种微生物；防御病原体的入侵，维持对共生菌的耐受。,7,一、组成肠相关淋巴组织的固有免疫细胞 二、肠道粘膜相关的固有免疫应答 三、上皮内淋巴细胞杀伤入侵病毒和修复损伤组织,黏膜免疫中的固有免疫应答,Mucosal lymphoid tissue in the human intestine.,The lamina propria and epithelium of the intestinal mucosa are discrete lymphoid compartments.,组成肠相关淋巴组织的固有免疫细胞,lntraepithelial lymphocytes express CCR9 and the integrin E:7, which binds to E-cadherin on epithelial cells. They are mostly CD8 T cells, some of which express the conventional : form of CD8 and others the CD8 : homodimer. CD8 T cells predominate in the epithelium, whereas CD8 T cells predominate in the lamina propria.,The lamina propria contains lgA-producing plasma cells, lymphocytes, effector T cells, dendritic cells, macrophages, and mast cells. T cells in the lamina propria of the small intestine express the integrin 4:7 and the chemokine receptor CCR9, which attracts them into the tissue from the bloodstream.,黏膜淋巴细胞与上皮细胞相互作用： 黏膜淋巴细胞：位于黏膜上皮细胞间和上皮细胞基底层一侧的T 淋巴细胞，包括固有类T 淋巴细胞和NK细胞。 分布部位特殊、功能发挥受控于上皮细胞表面各类MHC分子与其受体分子间的相互作用。 除了经典的MHC I 类和II 类分子，上皮细胞还表达范围广泛的各种非经典MHC分子，包括TL、HLA-E、MIC-A/-B、MR1和进化上与之高度同源的CD1d 分子，激活多种黏膜淋巴细胞。,物理免疫屏障功能 上皮细胞分泌的粘液防止微生物接近上皮细胞 上皮细胞产生的防御素具有抗菌活性 上皮细胞表达的TLR和NLR显示双重免疫功能 固有层中的DC和巨噬细胞具有炎症反应抑制作用和免疫调节作用,肠道黏膜相关的固有免疫应答,免疫屏障功能,分泌的粘液防止微生物接近,产生的防御素具有抗菌活性,含有大量嗜酸颗粒 分颗粒含有防御素、溶菌酶 对肠道微生物有杀灭功能,Epithelial cells have a crucial role in innate defense against pathogens. TLRs are present in intracellular vesicles or on the basolateral or apical surfaces of epithelial cells, where they recognize different components of invading bacteria. NOD1 and NOD2 pattern-recognition receptors are found in the cytoplasm and recognize cellwall peptides from bacteria. Both TLRs and NODs activate the NFB pathway leading to the generation of pro-inflammatory responses by epithelial cells. These include the production of chemokines such as CXCL8, CXCL 1 (GROa), CCL 1, and CCL2, which attract neutrophils and macrophages, and CCL20 and -defensin, which attract immature dendritic cells in addition to possessing antimicrobial properties. The cytokines IL-1 and IL-6 are also produced and activate macrophages and other components of the acute inflammatory response,表达的TLR和NLR显示双重免疫功能,Commensal bacteria can prevent inflammatory responses in the intestine. The pro-inflammatory transcription factor NFB pathway is activated in epithelial cells via the ligation of TLRs by pathogens (first two panels). Commensal bacteria have been found to inhibit this pathway and thus prevent inflammation. One way is by activation of the nuclear receptor PPAR, leading to the export of NFB from the nucleus (third panel). Another is by blocking the degradation of the inhibitor IB and thus retaining NFB in the cytoplasm (fourth panel).,小肠上皮细胞及固有层中DC上PRR的表达和功能可降低针对肠腔共生微生物的炎症反应。 能识别细菌鞭毛的PRR(NLR:表达于胞质中；TLR：表达于小肠上皮细胞基底膜一侧)，对共生微生物的炎症反应只有当微生物进入或穿越上皮细胞后才能产生。 识别LPS的TLR4在小肠上皮细胞及固有层DC上的表达皆下调。 能下调TLR信号转导的胞内调节蛋白（在固有层的DC中）可优势表达。,DC具有炎症反应抑制作用,IEL参与构筑黏膜防御屏障 IEL对病原体的杀伤功能 IEL的维稳和保护功能的功能,IEL杀伤入侵病毒和修复损伤组织,a型和b型粘膜上皮细胞间淋巴细胞（IEL）的主要功能 A. a型IEL。左：病毒感染粘膜上皮细胞；中：受感染细胞通过MHC I类分子向CD8 IEL展示病毒抗原肽，激活IEL；右：激活的IEL行 使典型的CTL功能，通过分泌Pf和Gz，以及通过Fas/FasL途径杀伤病毒感染的上皮细胞； B. b型IEL。左：发生应急改变（感染、损伤、接触毒性肽）的上皮细胞表达非经典MHC分子MIC-A、MIC-B和胸腺白血病抗原 (LT) ； 中：IEL表达NKG2D和CD8分子，分别与MIC-A/-B以及LT结合，IEL被激活；右：激活的IEL杀伤受到应急损伤的上皮细胞，机制同上 。,一、黏膜免疫系统器官化的淋巴组织 二、参与适应性黏膜免疫应答的免疫细胞 三、黏膜免疫中的抗体应答 四、黏膜免疫中T细胞介导的应答,黏膜免疫中的适应性免疫应答,黏膜免疫系统器官化的淋巴组织,派氏集合淋巴结与M细胞 散在性淋巴滤泡 肠系膜淋巴结,派氏集合淋巴结（Peyers 小结）,2019/6/10,肠系膜淋巴结（肿大）,肠系膜淋巴结,黏膜免疫系统含有大量效应淋巴细胞 黏膜免疫系统中独特的树突状细胞 黏膜固有层中T细胞的致敏和归巢,参与适应性黏膜免疫应答的免疫细胞,肠道中T细胞依赖的IgA 抗体类别转换机制 派氏集合淋巴结圆丘状隆起部位的DC 获取由M 细胞提交的肠腔抗原并迁移至滤泡区近旁后，将抗原提呈给初始 CD4 T 细胞并使之激活和分化成Th。Th与借助其BCR识别了抗原的B细胞发生相互作用，通过T-B间CD40L-CD40 的结合，B细胞分化成产生IgA的浆细胞。该过程受DC产生的一氧化氮及TGF-的促进。由此产生的浆细胞经由血 循环再归槽至固有层，所分泌的高亲和力IgA抗体，经过上皮细胞胞吞转换进入肠腔，与当初致敏的肠腔抗原结合。,Capture of antigens from the intestinal lumen by mononuclear cells in the lamina propria. First panel: soluble antigens such as food proteins might be transported directly across or between enterocytes, or there might be M cells in the surface epithelium outside Peyers patches. Second panel: enterocytes can capture and internalize antigen:antibody complexes by means of the FeRn on their surface and transport them across the epithelium by transcytosis. At the basal face of the epithelium, lamina propria dendritic cells expressing FeRn and other Fe receptors pick up and internalize the complexes. Third panel: an enterocyte infected with an intracellular pathogen undergoes apoptosis and its remains are phagocytosed by the dendritic cell. Fourth panel: mononuclear cells have been seen extending processes between the cells of the epithelium without disturbing its integrity. The cell process could pick up and internalize antigen from the gut lumen and then retract. The micrograph shows mononuclear cells, which may be dendritic cells or macrophages, (stained green with a fluorescent tag on the CD11 c molecule) in the lamina propria of a villus of mouse small intestine. The epithelium is not stained and appears black, but its luminal (outer) surface is shown by the white line. A cell process has squeezed between two epithelial cells and its tip is present in the lumen of the intestine. Magnification x200. Micrograph from Niess, J.H., eta/.: Science 2005, 307:254-258.,Capture of antigens from the intestinal lumen,参见图9-7,黏膜免疫系统中独特的树突状细胞,小肠淋巴细胞的激活和归巢,肠系膜淋巴结和派氏集合淋巴结中的DC，在胸腺基质淋巴生成素 (TSLP) 和其它因子的作用下表达视黄醇脱氢酶 (RALDH)，后者将维生素A转化 成视黄酸 (RC)。RC诱导，已被抗原活化的效应T细胞（及B细胞）表达趋化因子受体CCR9和整合素47，并进入血循环。,小肠淋巴细胞的激活和归巢,分布在黏膜固有层中的后毛细血管微静脉的内皮细胞表达MadCAM-1 (47 配体)，使CCR9+47+T细胞停留于该处并穿越微静脉到达固有层, 并变更其表型为CCR9+E7+T。 固有层上皮细胞表达CCL25 (CCR9配体)和E-钙粘素（E7配体），使效应性淋巴细胞选择性地归巢和停 于黏膜固有层。,Molecular control of intestine-specific homing of lymphocytes. Left panel: T and B lymphocytes primed by antigen in the Peyers patches or mesenteric lymph nodes arrive as effector lymphocytes in the bloodstream supplying the intestinal wall). The lymphocytes express the integrin 4:7, which binds specifically to MAdCAM-1 expressed selectively on the endothelium of blood vessels in mucosal tissues. This provides the adhesion signal needed for the emigration of cells into the lamina propria. Right panel: if primed in the small intestine, the effector lymphocytes also express the chemokine receptor CCR9, which allows them to respond to CCL25 (green circles) produced by epithelial cells of the small intestine; this enhances selective recruitment. Effector lymphocytes that have been primed in the large intestine do not express CCR9 but do express CCR10. This may respond to CCL28 (blue circles) produced by colon epithelial cells to fulfill a similar function. Lymphocytes that will enter the epithelial layer stop expressing the 4:7 integrin and instead express the E:7 integrin. The receptor for this is E-cadherin on the epithelial cells. These interactions may help keep lymphocytes in the epithelium once they have entered it.,分泌型IgA的特征 影响分泌型IgA抗体类别转换的因素 分泌型IgA的转运 分泌型IgA的意义 分泌型IgM可以代偿有缺陷的IgA,黏膜免疫中的抗体应答,参见图9-6,分泌型IgA的特征 影响分泌型IgA抗体类别转换的因素 分泌型IgA的转运 分泌型IgA的意义 分泌型IgM可以代偿有缺陷的IgA,黏膜免疫中的抗体应答,黏膜DC与炎症反应 Th17与黏膜免疫屏障 肠道蠕虫感染与Th2型免疫应答,黏膜免疫中T细胞介导的应答,对肠道蠕虫感染的保护性应答和病理性应答 大部分肠道蠕虫即可启动CD4 T 细胞介导的保护性应答也可诱导病理性应答。其中Th2相关应答有利于清除寄生虫，属保护性应答； 当DC接触抗原时产生IL-12，则产生Th1型应答。通常两种应答并存，若Th2介导的保护性应答不能处于优势地位，Th1型应答将使感 染持续，并造成小肠的慢性病理性损伤。,一、黏膜DC与免疫耐受 二、正常肠道的大量共生菌不引发有害的免疫反应 三、黏膜耐受的诱导,黏膜免疫中的免疫耐受和免疫调节,2019/6/10,黏膜DC-CD103+DC,iTreg,正常肠道的大量共生菌不引发有害的免疫反应,肠道共生菌对维持人体的健康发挥着重要的作用。 能够促进食物如纤维素的代谢； 能分解毒素；能产生重要的辅助因子如维生素K1和短链 脂肪酸。 通过竞争空间和营养成份可以抑制病原体在肠道的繁殖和 入侵共生菌能够直接作用于黏膜上皮细胞，对维持黏膜的 屏障功能有重要作用。 共生菌和其产物对于免疫系统的发展和功能有重要作用。,Local responses to commensals. Several local processes ensure peaceful coexistence between the microbiota and the host, allowing the commensal organisms to be recognized by the immune system without inducing inflammation or an immune response that would eliminate them. Commensal bacteria in the lumen gain access to the immune system via M cells in Peyers patches and isolated follicles (left panel). Uptake and presentation of these noninvasive organisms by resting dendritic cells generates lgA-switched B cells that localize in the lamina propria as lgA-producing plasma cells (right panel). The secretory lgA that is produced limits the access of commensals to the epithelium and helps prevent their penetration. This is assisted further by the presence of thick layers of mucus, which also contain mucin glycoproteins that have antibacterial properties. In addition, stimulation of pattern-recognition receptors on epithelial cells and local leukocytes induces the production of antimicrobial peptides such as defensins.,A. 健康小鼠饲以卵清蛋白，7天后，用同一抗原加佐剂作皮下免疫，14天后测定小鼠针对卵清蛋白的血清抗体和T细胞应答水平。 B. 同一品系的对照小鼠，喂饲无关蛋白，而7天后注射的卵清蛋白属首次免疫，诱导出的典型保护性免疫针对卵清蛋白。 C. B组小鼠以无关蛋白喂饲后若注射同一无关蛋白，同样可诱导针对该无关蛋白的粘膜耐受。,黏膜耐受的诱导,一、病原体感染与宿主免疫反应之间的消长 决定了感染的结局 二、针对共生菌的免疫应答与肠道疾病 三、肠道中与免疫应答相关的一些临床疾病,黏膜免疫与疾病,Mucosal infections are one of the biggest health problems worldwide. Most of the pathogens that cause the deaths of large numbers of people are those of mucosal surfaces or enter the body through these routes. Respiratory infections are caused by numerous bacteria (such as Streptococcus pneumoniae and Haemophilus influenzae, which cause pneumonia, and Bordetella pertussis, the cause of whooping cough) and viruses (such as influenza and respiratory syncytial virus). Diarrheal diseases are caused by both bacteria (such as the cholera bacterium Cholera vibrio) and viruses (such as rotaviruses). The human immunodeficiency virus (HIV) that causes AIDS enters through the mucosa of the urogenital tract or is secreted into breast milk and is passed from mother to child in this way. The bacterium Mycobacterium tuberculosis, which causes tuberculosis, also enters through the respiratory tract. Measles manifests itself as a systemic disease, but it originally enters via the oral/respiratory route. Hepatitis B is also a sexually transmitted virus. Finally, parasitic worms inhabiting the intestine cause chronic debilitating disease and premature death. Most of these deaths, especially those from acute respiratory and diarrheal diseases, occur in children under 5 years old in the developing world, and there are still no effective vaccines against many of these pathogens. Numbers shown are the most recent estimated figures available (The Global Burden of Disease: 2004 Update. World Health Organization, 2008). *Does not include deaths from liver cancer or cirrhosis resulting from chronic infection.,Infection by Clostridium difficile. Treatment with antibiotics causes massive death of the commensal bacteria that normally colonize the colon. This allows pathogenic bacteria to proliferate and to occupy an ecological niche that is normally occupied by harmless commensal bacteria. Clostridium difficile is an example of a pathogen producing toxins that can cause severe bloody diarrhea in patients treated with antibiotics.,病原体感染与宿主免疫反应之间的消长决定了感染的结局,Shigella flexneri, a cause of bacterial dysentery, infects intestinal epithelial cells, triggering activation of the NFB pathway. Shigella flexneri binds to M cells and is translocated beneath the gut epithelium (first panel). The bacteria infect intestinal epithelial cells from their basal surface and are released into the cytoplasm (second panel). Muramyl tripeptides containing diaminopimelic acid in the cell walls of the shigellae bind to and oligomerize the protein NOD1. Oligomerized NOD1 binds the serine/ threonine kinase RIPK2, which triggers activation of the NFB pathway , leading to the transcription of genes for chemokines and cytokines (third panel). Activated epithelial cells release the chemokine CXCL8, which acts as a neutrophil chemoattractant (fourth panel). IB, inhibitor of NFB; IK, IB kinase.,针对共生菌的免疫应答与肠道疾病,Mucosal dendritic cells regulate the induction of tolerance and immunity in the intestine. Under normal conditions (left panels), dendritic cells are present in the mucosa underlying the epithelium and can acquire antigens from foods or commensal organisms. They take these antigens to the draining mesenteric lymph node, where they present them to naive CD4 T cells. There is, however, constitutive production by epithelial cells and mesenchymal cells of molecules such as TGF-, thymic stromal lymphopoietin (TSLP), and prostaglandin E2 (PGE2), which maintain the local dendritic cells in a quiescent state with low levels of co-stimulatory molecules, so that when they present antigen to naive CD4 T cells, anti-inflammatory or regulatory T cells are generated. These recirculate back to the intestinal wall and maintain tolerance to the harmless antigens. Invasion by pathogens or a massive influx of commensal bacteria (right panels) overcomes these homeostatic mechanisms, resulting in full activation of local dendritic cells and their expression of co-stimulatory molecules and pro-inflammatory cytokines such as I L -12. Presentation of antigen to naive CD4 T cells in the mesenteric lymph node