免疫学黏膜免疫课件

1、黏膜免疫Mucosal Immune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粘膜免疫与疾病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 as

2、sociated with these tissues, such as the salivary glands and lachrymal glands. The lactating breast is also part of the 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，构成粘膜免疫系统（mucosal immune system）。包括启动和行使免疫应答的粘膜下固有层中各种散在的免疫细胞和一些器官化的淋巴组织，还包括与此相关的多种内分泌腺体：胰腺、眼结膜和泪腺、唾液腺以及乳腺。因而黏膜免疫系统亦称黏膜相关淋巴组织（muco

3、sa-associated lymphoid tissue, MALT）。一、黏膜免疫系统的结构特点二、黏膜免疫系统的应答特点黏膜免疫系统与免疫应答黏膜免疫系统的结构特点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 l

4、ymphoid cells and diffuse follicles.小肠黏膜免疫系统的各种细胞成分和器官化的淋巴组织 肠腔固有层肠系膜粘膜上皮DCM细胞小肠上皮细胞 上皮内淋巴细胞 (IEL)绒毛共生菌粘液浆细胞隐窝杯状细胞IgA巨噬细胞肠腺嗜酸细胞B细胞T细胞抗菌肽DC输出淋巴管肥大细胞分立的 淋巴滤泡 派氏集合淋巴结滤泡T细胞肠系膜淋巴结粘膜免疫系统的特点 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。 启用特化的抗原摄取机制，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

5、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。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The lamina propria and epithelium of the intestinal mucosa are discrete lymphoid compartments. The lamina pro

6、pria contains a heterogeneous mixture of lgA-producing plasma cells, lymphocytes with a memory phenotype , conventional CD4 and CD8 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

7、 CCR9, which attracts them into the tissue from the bloodstream. 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 a:B form of CD8 and others the CD8a:a homodimer. CD4 T ce

8、lls predominate in the lamina propria, whereas CD8 T cells predominate in the epithelium.组成肠相关淋巴组织的固有免疫细胞 粘膜淋巴细胞及其与上皮细胞相互作用的分子机制图中所示粘膜淋巴细胞主要指位于粘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。此类细胞不仅分布部位特殊，而且功能发挥皆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。有意义的是，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/

9、-B、MR1和进化上与之高度同源的CD1d 分子，激活多种粘膜淋巴细胞。 TL MHC II MHC I TL MIC- MIC - HLA-E CD1d/ MR1 A/-B A/-B -GalCel CD8 CD4 CD8 CD8 NKG2D CD94/ TCR TCR TCR TCR TCR NKG2ATCR TCR TCR TCR NK NKT MAITCD8 CD4 T CD8 T CD8 TGF- IFN-,IL-4 Pf,Gz,FasL IL-6, KGF TNF-, Pf, Gz, IFN-,IL-4 ? TNF- IFN- FasL 调节 Th1/Th2 毒性 炎症, 修复，

10、炎症 毒性 Th1/Th2 ？ 功能 毒性 抗炎 功能？BCRB受体上皮细胞配体粘膜淋巴细胞分泌因子功能 TL: 非经典MHC I 类分子 胸腺白血病抗原；MIC: MHC I 类链相关分子；CD1d/a-GalCel: 分化抗原CD1d分子提呈的 半乳糖神经 酰胺； MR1: MHC相关I 类分子；MAIT: MR1限制性粘膜相关恒定链T 细胞; Pf: 穿孔素；Gz: 颗粒酶。KGF: 角朊细胞生长因子。 肠道上皮细胞的免疫屏障功能肠道上皮细胞分泌的粘液防止微生物接近上皮细胞肠道上皮细胞产生的防御素和细胞因子具有抗菌活性肠道上皮细胞表达的TLR和NLR显示双重免疫功能固有层中的DC和巨噬细

11、胞具有炎症反应抑制作用和免疫调节作用肠道粘膜相关的固有免疫应答Many barriers prevent pathogens from crossing epithelia and colonizing tissues. Surface epithelia provide mechanical, chemical, and microbiological barriers to infection.小肠黏膜中固有免疫应答的调控机制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。上端：能识别细菌鞭毛的PRR仅作为NLR表达于胞质中和作为TLR表达于小肠上皮细胞基

12、底膜一侧，因而PRR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。右下端：识别LPS的TLR4在小肠上皮细胞及固有层DC上的表达皆下调。而且固有层DC中TLR信号并不诱导炎症基因的表达，因为其中能下调TLR信号转导的胞内调节蛋白可优势表达。TLRTLR4 DCNLR 细菌PAMP小肠上皮层固有层Epithelial cells have a crucial role in innate defense against pathogens. TLRs are present in intracellular vesicles or on the basolateral or a

13、pical 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-infla

14、mmatory 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 cytokine

15、s IL-1 and IL-6 are also produced and activate macrophages and other components of the acute inflammatory response. The epithelial cells also express MIC-A and MIC-B and other stress-related nonclassical MHC molecules, which can be recognized by cells of the innate immune system. IB, inhibitor of NF

16、B.Commensal bacteria can prevent inflammatory responses in the intestine. The pro-inflammatory transcription factor NFB pathwayis 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 inflam

17、mation. One way is by activation of the nuclear receptor PPAR, leading to the export of NFB fromthe nucleus (third panel). Another is by blocking the degradation of the inhibitor IB and thus retaining NFB in the cytoplasm (fourth panel).IEL参与构筑粘膜防御屏障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病毒 食物抗原

18、（谷朊肽）TCR MHC I类分子 MIC-A/-B NKG2D LT CD8 CD8 Fas FasL Gz (颗粒酶) Pf (穿孔素) 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

19、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 。上皮细胞CD8 IELABa型IELb型IEL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系统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Uptake and transport of antigens by M cells. The first three panels show uptake via M cells in the follicle

20、-associated epithelium of Peyers patches. These have convoluted basal membranes that form pockets within the epithelial layer, allowing close contact with lymphocytes and other cells. This favors the local transport of antigens that have been taken up from the intestine by the M cells and their deli

21、very to dendritic cells for antigen presentation. The micrograph of part of a Peyers patch on the right shows epithelial cells (dark blue), some of which are M cells that form pockets where T cells (red) and B cells (green) accumulate. The cells have been stained with fluorescently labeled antibodie

22、s specific for individual cell types. Micrograph from Brandtzaeg, P., eta/.: lmmunol. Today 1999, 20:141-151.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Capture of antigens from the intestinal lumen by mononuclear cells in the lamina propria. First panel: soluble antigens such as f

23、ood 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 e

24、pithelium 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

25、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 de

26、ndritic 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

27、 epithelial cells and its tip is present in the lumen of the intestine. Magnification x200. Micrograph from Niess, J.H., eta/.: Science 2005, 307:254-258.参见图9-7CCR9CCL2547DCCCR947 TSLPRC T肠系膜淋巴结微静脉MadCAM-1E-钙粘素E7固有层肠系膜M细胞固有层上皮细胞TT上皮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

28、 (RALDH)，后者将维生素A转化成视黄酸 (RC)，在RC的作用下，已被抗原活化的效应T细胞（及B细胞）被激发，诱导性表达趋化因子受体CCR9和整合素47，并进入血循环。由于分布在粘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。而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留于粘膜固有层。 Molecular control of intestine-specific homing of lymphocyte

29、s. 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 endotheli

30、um 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

31、) 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 fun

32、ction. 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

33、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。 CD40L CD40DC

34、初始T激活的ThNOB浆母细胞TGF-经过血流派氏集合淋巴结淋巴滤泡固有层肠腔基底膜上皮细胞肠腔抗原IgAIgA分泌IgA浆细胞DC B7 CD28M 细胞参见图9-6粘膜DC与炎症反应Th17与粘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Pathological responses to intestinal helminths. If the CD4 T-cell response to a helminth parasite is polarized to produce predominantly T H 1 effector T cells (for exam

35、ple, by the production of IL-12 by dendritic cells), it does not clear the pathogen. If not balanced by a protective TH2 response, the T H 1 response leads to persistent infection and chronic intestinal pathology. M1 macrophage, classically activated macrophage.Protective responses to intestinal hel

36、minths. Most intestinal helminths induce both protective and pathological immune responses by CD4 T cells. T H2 responses tend to be protective, creating an unfriendly environment for the parasite, and leading to its expulsion and the generation of protective immunity (see the text for details). M2

37、macrophage, alternatively activated macrophage.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。置换被寄生的上皮细胞，用粘液阻止寄生虫粘附，促其脱落。肥大细胞产生TNF, 组胺等介质，募集炎症细胞, 重塑粘膜。产生能固定补体的抗体IgG2a。活化的巨噬细胞以其产物引起组织损

38、伤，诱导组织重塑。IgE武装肥大细胞，介导ADCC。嗜碱粒细胞通过主要碱性蛋白 (MBP) 杀伤寄生虫。激活巨噬细胞招募和激活嗜酸粒细胞驱动 B 淋巴细胞产生 IgE招募肥大细胞，抗蠕虫驱动B淋巴细胞产生IgG2aIL-13IL-5IL-4IL-9IL-3IFN-诱导上皮细胞修复,分泌粘液.Th-2Th-1DC 初始CD4 T保护效应宿主损伤一、粘膜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、粘膜耐受的诱导黏膜免疫中的免疫耐受和免疫调节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

39、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 i

40、nducing 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-sw

41、itched 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 cont

42、ain 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.1mmune priming and tolerance are different outcomes of intestinal exposure

43、 to antigen. Left panel, the intestinal immune system generates protective immunity against antigens that are a threat to the host, such as pathogenic organisms and their products. lgA antibodies are produced locally, serum lgG and lgA are made, and the appropriate effector T cells are activated in

44、the intestine and elsewhere. When the antigen suppressed. This phenomenon is known as oral tolerance and is shown in the right-hand panels, where it has been induced by feeding a protein such as ovalbumin to a normal mouse. First, mice are fed either ovalbumin or a different protein as a control. Se

45、ven days later, the mice are immunized subcutaneously with ovalbumin and an adjuvant; 2 weeks later, systemic immune responses such as serum antibodies and T-cell function are measured. Mice fed ovalbumin have a lower ovalbumin-specific systemic immune response than those fed the control protein. In

46、 the case of commensal bacteria, there is evidence of local lgA antibody production, but no primary systemic antibody responses, and effector T cells are not activated in either site. Profound tolerance of T-cell responses is retained thereafter, but the systemic immune system remains ignorant of co

47、mmensals unless they gain access to the circulation, when a primary systemic immune response will result. is encountered again, there is effective memory, ensuring rapid protection. Harmless antigens such as food proteins or antigens from commensal bacteria induce tolerance, either locally, or both

48、locally and systemically. They lack the danger signals needed to activate local antigen-presenting cells, or do not invade sufficiently to cause inflammation. In the case of food proteins, there is little or no local lgA antibody production or primary systemic antibody response, nor are effector T c

49、ells activated. Subsequent local and systemic immune responses to challenge are also specifically粘膜耐受的诱导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。特异应答 7d7d14d14dAB特异应答 粘膜耐受保护性 免疫 7d14d

50、C特异应答 粘膜 免疫一、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粘膜免疫与疾病Intestinal pathogens and infectious disease in humans. Many species of bacteria, viruses, and parasites can cause disease in the human intestine.Mucosal infections are one of the biggest health problems worldwide. Most

51、 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 pertussi

52、s, 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

53、 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

54、 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 yea

55、rs 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 cirrhos

56、is resulting from chronic infection.1nfection by Clostridium difficile. Treatment with antibiotics causes massive death of the commensal bacteria that normally colonize thecolon. T his allows pathogenic bacteria to proliferate and to occupy an ecological niche that is normally occupied by harmless c

57、ommensal 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 t

58、he 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

59、 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 chemok

60、ine CXCL8, which acts as a neutrophil chemoattractant (fourth panel). IB, inhibitor of NFB; IK, IB kinase.炎症性肠炎乳糜泻食物过敏（I型超敏反应）微生物的持续感染与肿瘤肠道中与免疫应答相关的一些临床疾病Mucosal dendritic cells regulate the induction of tolerance and immunity in the intestine. Under normal conditions (left panels), dendritic cells