黏膜免疫研究生

1、黏膜免疫Mucosal Immune,黏膜免疫系統(tǒng)（mucosal immune system）： 直接接觸病原體的解剖部位并能夠分泌粘液的上皮細胞所覆蓋，構(gòu)成黏膜免疫系統(tǒng)。 廣泛分布于呼吸道、胃腸道、泌尿生殖道黏膜下及一些外分泌腺體（唾液腺、淚腺、乳腺）處的淋巴組織。 執(zhí)行局部特異性免疫功能的主要場所。,The mucosal immune system. The tissues of the mucosal im

2、mune 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

3、 and lachrymal glands. The lactating breast is also part of the mucosal immune system.,黏膜免疫系統(tǒng)亦稱黏膜相關(guān)淋巴組織（mucosa-associated lymphoid tissue, MALT）。,黏膜免疫系統(tǒng)與免疫應答黏膜免疫系統(tǒng)中的固有免疫應答黏膜免疫系統(tǒng)中的適應性免疫應答黏膜免疫中的免疫耐受和免疫調(diào)節(jié)黏膜免疫與疾病,主要內(nèi)容,小腸

4、黏膜免疫系統(tǒng)的各種細胞成分和器官化的淋巴組織,Cross-sectional diagram of the mucous membrane lining the intestine showing a nodule of lymphoid follicles that constitutes a Peyer’s patch in the submucosa. The intestinal lamina propria contains

5、loose clusters of lymphoid cells and diffuse follicles.,黏膜免疫系統(tǒng)與免疫應答（結(jié)構(gòu)和應答特點）,黏膜免疫系統(tǒng)的特點,解剖特征 －粘膜上皮和淋巴組織間因相互作用而聯(lián)系緊密。 －由散在的淋巴組織和器官化的結(jié)構(gòu)（如派氏集合淋巴結(jié)、 分立的淋巴濾泡和扁桃體）共同組成。 －啟用抗原攝取機制，如出現(xiàn)派氏集合淋巴結(jié)和M細

6、胞。 效應機制 －在無感染發(fā)生的情況下?lián)碛写罅炕罨腡細胞和記憶細胞。 －存在非特異性激活的“天然”效應性T細胞和記憶性T細胞。 －大量啟用分泌型IgA抗體。 －涉及各種共生微生物菌叢。 免疫調(diào)節(jié) －可主動下調(diào)針對食物和其它共生性抗原的強勢免疫應答。 －可激活抑制性巨噬細胞及誘導耐受的樹突

7、狀細胞。,,,*黏膜覆蓋面大；腸腔中充滿各種微生物；防御病原體的入侵，維持對共生菌的耐受。,7,一、組成腸相關(guān)淋巴組織的固有免疫細胞二、腸道粘膜相關(guān)的固有免疫應答三、上皮內(nèi)淋巴細胞殺傷入侵病毒和修復損傷組織,黏膜免疫中的固有免疫應答,Mucosal lymphoid tissue in the human intestine.,,The lamina propria and epithelium of the intestinal

8、mucosa are discrete lymphoid compartments.,組成腸相關(guān)淋巴組織的固有免疫細胞,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 e

9、xpress 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 pl

10、asma 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

11、them into the tissue from the bloodstream.,黏膜淋巴細胞與上皮細胞相互作用：黏膜淋巴細胞：位于黏膜上皮細胞間和上皮細胞基底層一側(cè)的T 淋巴細胞，包括固有類T 淋巴細胞和NK細胞。 分布部位特殊、功能發(fā)揮受控于上皮細胞表面各類MHC分子與其受體分子間的相互作用。 除了經(jīng)典的MHC I 類和II 類分子，上皮細胞還表達范圍廣泛的各種非經(jīng)典MHC分子，包括TL、HLA-E、MIC-A/-B、

12、MR1和進化上與之高度同源的CD1d 分子，激活多種黏膜淋巴細胞。,物理免疫屏障功能 上皮細胞分泌的粘液防止微生物接近上皮細胞 上皮細胞產(chǎn)生的防御素具有抗菌活性 上皮細胞表達的TLR和NLR顯示雙重免疫功能 固有層中的DC和巨噬細胞具有炎癥反應抑制作用和免疫調(diào)節(jié)作用,腸道黏膜相關(guān)的固有免疫應答,免疫屏障功能,分泌的粘液防止微生物接近,,產(chǎn)生的防御素具有抗菌活性,,含有大量嗜酸顆粒 分顆粒含有防御素、溶菌酶 對腸道微生

13、物有殺滅功能,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 com

14、ponents 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 NF?B pathway leading to the generation

15、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 attra

16、ct 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,表達的TLR和NLR顯示雙

17、重免疫功能,,Commensal bacteria can prevent inflammatory responses in the intestine. The pro-inflammatory transcription factor NF?B pathway is activated in epithelial cells via the ligation of TLRs by pathogens (first two pane

18、ls). 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 NF?B from the nucleus (third panel). Another

19、 is by blocking the degradation of the inhibitor I?B and thus retaining NF?B in the cytoplasm (fourth panel).,小腸上皮細胞及固有層中DC上PRR的表達和功能可降低針對腸腔共生微生物的炎癥反應。能識別細菌鞭毛的PRR(NLR:表達于胞質(zhì)中；TLR：表達于小腸上皮細胞基底膜一側(cè))，對共生微生物的炎癥反應只有當微生物進入或穿越上皮細

20、胞后才能產(chǎn)生。識別LPS的TLR4在小腸上皮細胞及固有層DC上的表達皆下調(diào)。能下調(diào)TLR信號轉(zhuǎn)導的胞內(nèi)調(diào)節(jié)蛋白（在固有層的DC中）可優(yōu)勢表達。,DC具有炎癥反應抑制作用,IEL參與構(gòu)筑黏膜防御屏障IEL對病原體的殺傷功能IEL的維穩(wěn)和保護功能的功能,IEL殺傷入侵病毒和修復損傷組織,,a型和b型粘膜上皮細胞間淋巴細胞（IEL）的主要功能A. a型IEL。左：病毒感染粘膜上皮細胞；中：受感染細胞通過MHC I類分子向CD8

21、IEL展示病毒抗原肽，激活IEL；右：激活的IEL行使典型的CTL功能，通過分泌Pf和Gz，以及通過Fas/FasL途徑殺傷病毒感染的上皮細胞；B. b型IEL。左：發(fā)生應急改變（感染、損傷、接觸毒性肽）的上皮細胞表達非經(jīng)典MHC分子MIC-A、MIC-B和胸腺白血病抗原 (LT) ；中：IEL表達NKG2D和CD8分子，分別與MIC-A/-B以及LT結(jié)合，IEL被激活；右：激活的IEL殺傷受到應急損傷的上皮細胞，機制同上 。,

22、,,,,一、黏膜免疫系統(tǒng)器官化的淋巴組織二、參與適應性黏膜免疫應答的免疫細胞三、黏膜免疫中的抗體應答四、黏膜免疫中T細胞介導的應答,黏膜免疫中的適應性免疫應答,,黏膜免疫系統(tǒng)器官化的淋巴組織,派氏集合淋巴結(jié)與M細胞散在性淋巴濾泡腸系膜淋巴結(jié),,派氏集合淋巴結(jié)（Peyer’s 小結(jié)）,2024/2/27,腸系膜淋巴結(jié)（腫大）,腸系膜淋巴結(jié),黏膜免疫系統(tǒng)含有大量效應淋巴細胞黏膜免疫系統(tǒng)中獨特的樹突狀細胞黏膜固有層中T細胞的致敏

23、和歸巢,參與適應性黏膜免疫應答的免疫細胞,腸道中T細胞依賴的IgA 抗體類別轉(zhuǎn)換機制派氏集合淋巴結(jié)圓丘狀隆起部位的DC 獲取由M 細胞提交的腸腔抗原并遷移至濾泡區(qū)近旁后，將抗原提呈給初始CD4 T 細胞并使之激活和分化成Th。Th與借助其BCR識別了抗原的B細胞發(fā)生相互作用，通過T-B間CD40L-CD40的結(jié)合，B細胞分化成產(chǎn)生IgA的漿細胞。該過程受DC產(chǎn)生的一氧化氮及TGF-?的促進。由此產(chǎn)生的漿細胞經(jīng)由血循環(huán)再歸槽至固

24、有層，所分泌的高親和力IgA抗體，經(jīng)過上皮細胞胞吞轉(zhuǎn)換進入腸腔，與當初致敏的腸腔抗原結(jié)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 ac

25、ross or between enterocytes, or there might be M cells in the surface epithelium outside Peyer's patches. Second panel: enterocytes can capture and internalize antigen:antibody complexes by means of the FeRn on their

26、 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 p

27、anel: 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

28、 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 mac

29、rophages, (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 show

30、n 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.,Captu

31、re of antigens from the intestinal lumen,,參見圖9-7,黏膜免疫系統(tǒng)中獨特的樹突狀細胞,小腸淋巴細胞的激活和歸巢,,腸系膜淋巴結(jié)和派氏集合淋巴結(jié)中的DC，在胸腺基質(zhì)淋巴生成素 (TSLP) 和其它因子的作用下表達視黃醇脫氫酶 (RALDH)，后者將維生素A轉(zhuǎn)化成視黃酸 (RC)。RC誘導，已被抗原活化的效應T細胞（及B細胞）表達趨化因子受體CCR9和整合素?4?7，并進入血循環(huán)。,小腸淋巴細胞

32、的激活和歸巢,,分布在黏膜固有層中的后毛細血管微靜脈的內(nèi)皮細胞表達MadCAM-1 (?4?7 配體)，使CCR9+?4?7+T細胞停留于該處并穿越微靜脈到達固有層, 并變更其表型為CCR9+?E?7+T。固有層上皮細胞表達CCL25 (CCR9配體)和E-鈣粘素（?E?7配體），使效應性淋巴細胞選擇性地歸巢和停于黏膜固有層。,,,Molecular control of intestine-specific homing of l

33、ymphocytes. Left panel: T and B lymphocytes primed by antigen in the Peyer's patches or mesenteric lymph nodes arrive as effector lymphocytes in the bloodstream supplying the intestinal wall). The lymphocytes express

34、 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

35、 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

36、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 epith

37、elial 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

38、 cells. These interactions may help keep lymphocytes in the epithelium once they have entered it.,分泌型IgA的特征影響分泌型IgA抗體類別轉(zhuǎn)換的因素分泌型IgA的轉(zhuǎn)運分泌型IgA的意義分泌型IgM可以代償有缺陷的IgA,黏膜免疫中的抗體應答,,參見圖9-6,分泌型IgA的特征影響分泌型IgA抗體類別轉(zhuǎn)換的因素分泌型IgA的轉(zhuǎn)運

39、分泌型IgA的意義分泌型IgM可以代償有缺陷的IgA,黏膜免疫中的抗體應答,黏膜DC與炎癥反應Th17與黏膜免疫屏障腸道蠕蟲感染與Th2型免疫應答,黏膜免疫中T細胞介導的應答,,對腸道蠕蟲感染的保護性應答和病理性應答大部分腸道蠕蟲即可啟動CD4 T 細胞介導的保護性應答也可誘導病理性應答。其中Th2相關(guān)應答有利于清除寄生蟲，屬保護性應答；當DC接觸抗原時產(chǎn)生IL-12，則產(chǎn)生Th1型應答。通常兩種應答并存，若Th2介導的保

40、護性應答不能處于優(yōu)勢地位，Th1型應答將使感染持續(xù)，并造成小腸的慢性病理性損傷。,一、黏膜DC與免疫耐受二、正常腸道的大量共生菌不引發(fā)有害的免疫反應三、黏膜耐受的誘導,黏膜免疫中的免疫耐受和免疫調(diào)節(jié),2024/2/27,黏膜DC---CD103+DC,iTreg,正常腸道的大量共生菌不引發(fā)有害的免疫反應,腸道共生菌對維持人體的健康發(fā)揮著重要的作用。能夠促進食物如纖維素的代謝；能分解毒素；能產(chǎn)生重要的輔助因子如維生素K1和短鏈

41、脂肪酸。通過競爭空間和營養(yǎng)成份可以抑制病原體在腸道的繁殖和入侵共生菌能夠直接作用于黏膜上皮細胞，對維持黏膜的屏障功能有重要作用。共生菌和其產(chǎn)物對于免疫系統(tǒng)的發(fā)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, allow

42、ing 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 cell

43、s in Peyer's 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-pr

44、oducing 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 mu

45、cus, 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 p

46、eptides such as defensins.,A. 健康小鼠飼以卵清蛋白，7天后，用同一抗原加佐劑作皮下免疫，14天后測定小鼠針對卵清蛋白的血清抗體和T細胞應答水平。B. 同一品系的對照小鼠，喂飼無關(guān)蛋白，而7天后注射的卵清蛋白屬首次免疫，誘導出的典型保護性免疫針對卵清蛋白。C. B組小鼠以無關(guān)蛋白喂飼后若注射同一無關(guān)蛋白，同樣可誘導針對該無關(guān)蛋白的粘膜耐受。,黏膜耐受的誘導,一、病原體感染與宿主免疫反應之間的消長 決

47、定了感染的結(jié)局二、針對共生菌的免疫應答與腸道疾病三、腸道中與免疫應答相關(guān)的一些臨床疾病,黏膜免疫與疾病,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 sur

48、faces 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 caus

49、e 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

50、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 tuberculos

51、is, 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 transmitte

52、d 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 u

53、nder 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 Updat

54、e. 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 c

55、ommensal bacteria that normally colonize thecolon. This allows pathogenic bacteria to proliferate and to occupy an ecological niche that is normally occupied by harmless commensal bacteria. Clostridium difficile is an e

56、xample of a pathogen producing toxins that can cause severe bloody diarrhea in patients treated with antibiotics.,病原體感染與宿主免疫反應之間的消長決定了感染的結(jié)局,,Shigella flexneri, a cause of bacterial dysentery, infects intestinal epithelia

57、l cells, triggering activation of the NF?B 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 surfac

58、e 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/ th

59、reonine kinase RIPK2, which triggers activation of the NF?B pathway , leading to the transcription of genes for chemokines and cytokines (third panel). Activated epithelial cells release the chemokine CXCL8, which acts a

60、s a neutrophil chemoattractant (fourth panel). I?B, inhibitor of NF?B; I?K, I?B kinase.,,針對共生菌的免疫應答與腸道疾病,Mucosal dendritic cells regulate the induction of tolerance and immunity in the intestine. Under normal conditions

61、(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 pr

62、esent 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 ma

63、intain 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 reci

64、rculate 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 ful

65、l 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 by these de

66、ndritic cells causes differentiation into cells, leading to a full immune response.,炎癥性腸炎乳糜瀉食物過敏（I型超敏反應）微生物的持續(xù)感染與腫瘤,腸道中與免疫應答相關(guān)的一些臨床疾病,,Inflammatory bowel disease（炎癥性腸炎）,一種特殊的慢性腸道炎癥性疾病。 臨床上，患者會表現(xiàn)為反復的腹痛、腹瀉、粘液血便，甚至出現(xiàn)各種

67、全身并發(fā)癥如視物模糊、關(guān)節(jié)疼痛、皮疹等。 患者腸道不能正常吸收進食的碳水化合物、蛋白質(zhì)、脂肪、維生素及多種微量元素，加上腸道炎癥或服用的藥物可能造成食欲不佳，因此炎性腸病常伴隨著不同程度的營養(yǎng)不良，甚至影響小孩正常的生長發(fā)育。,Celiac disease（乳糜瀉）,炎癥性小腸黏膜疾病 小腸絨毛萎縮、吸收不良，營養(yǎng)缺陷 患者有遺傳傾向（HLA-DQA1*0501-HLA-DQB1*0301） 患者對谷脘蛋白異常敏感 正常人小腸

68、黏膜細胞內(nèi)有多肽分解酶，可將其分解為更小分子的無毒物質(zhì)，但在活動性乳糜瀉病人，腸黏膜細胞酶活性不足，不能將其分解而致病。,A hypothesis to explain antibody production against tissue transglutaminase (tTG) in the absence of T cells specific for tTG in celiac patients. tTG-reactive B