模式識別受體

1、.Innate Immune recognition.Threats to the individual.Protection from microbial invasion.Nobel Prize 2011 innate immunity.Nobel Prize 2011nJules A. Hoffmann: In 1996, found “Toll” gene has a role in the flys immunity to fungal infections. nBruce A. Beutler: in 1998, Bruce A. Beutler and colleagues di

2、scovered that the Toll-like receptors (TLRs) act as the principal sensors of infection in mammals. nRalph M. Steinman 1973，Ralph Steinman isolate Dentritic Cell)。 DC can activate T cell. DC is the birdge between innate immunity and adaptive immunity.Toll PathwayDrosophila.They all deserve the Nobel

3、PrizeRuslan MedzhitovCharles Janeway 19432003 Takashi Fujita, Shizuo Akira PRRTLRRLRYale Univ.Yale Univ.Kyoto Univ., Osaka Univ. .pathogen associated molecular patterns, PAMPsConserved pattern found only in pathogens, not in host cells。 (Charles Jenaway 1989，at Cold spring harbor meeting)Typical PAM

4、Ps：1、Glycans：G- bacteria (lipopolysaccharide, LPS）; G+ bacteria (peptidoglycan)； Bacterial flagellin2、Nucleotide: Virus DNA/RNA.PAMPsGlucanPeptidoglycanLPS Flagellin。.pattern recognition receptors, PRR：Receptors, on the surface or inside the cells, for those pathogen associated molecule patterns. Ty

5、pes of PRRs：Toll-like receptors; TLRsRNA sensor（RIG-I, MDA5）DNA sensor（AIM2，DAI）NOD-like receptors； NLRsC-Lectin receptorsOther PRRs .PRR-PAMPs engagement activates phagocytes.Toll like Receptor （TLR）nNature. 1997 Jul 24;388(6640):394-7.nA human homologue of the Drosophila Toll protein signals activ

6、ation of adaptive immunity.nMedzhitov R, Preston-Hurlburt P, Janeway CA Jr.nSourcenSection of Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06520-8011, USA.nAbstractnWe report here the cloning and characterization of a human homologue of the Drosophila toll protein (Toll)

7、 which has been shown to induce the innate immune response in adult Drosophila. Like Drosophila Toll, human Toll is a type I transmembrane protein with an extracellular domain consisting of a leucine-rich repeat (LRR) domain, and a cytoplasmic domain homologous to the cytoplasmic domain of the human

8、 interleukin (IL)-1 receptor. Both Drosophila Toll and the IL-1 receptor are known to signal through the NF-kappaB pathway. We show that a constitutively active mutant of human Toll transfected into human cell lines can induce the activation of NF-kappaB and the expression of NF-kappaB-controlled ge

9、nes for the inflammatory cytokines IL-1, IL-6 and IL-8, as well as the expression of the co-stimulatory molecule B7.1, which is required for the activation of naive T cells.PUBMED search “Toll like receptor” 24700 papers.1-1) Cellular distribution of TLRsCell membraneEndosome membrane.PRRs in PMN.1-

10、2) TLRs expression in cellsImmune cells and some epithelia cells express TLRs .TLRs expressed in immune cells.1-3) Structure of TLRs* Homo-or heterodimers, or together with other molecules .1-4) TLRs signaling pathway：MyD88 dependent pathway: All TLRs except 3 MyD88 independent pathway:TLR3; part of

11、 TLR4effector genes.TLRs signaling pathway：.TLRs signaling pathway：.1.5) Negative regulation of TLRs signaling.1-6) Role of TLRs in immune responsenInnate immunity:Activate phagocytosis and killing: regulated expression of genes of phagocytosis Promoting secretion of cytokines/ chemokines : IL1, IL6

12、, TNFa, IFNs, CXCLs, CCLs (recruit other immune cells)Promote secretion of anti-peptide: eg: Defensins.1-6) Role of TLRs in immune responsenAdaptive immunity:TLRs induce DC maturation: cytokine secretion; costimulatory molecules - DC activation - present antigen to activate T cellsTLRs signaling inf

13、luences Th cell differentiation: to influence the differentiation of T cells: Th1, Th2, Th17TLRs induce Treg activation: regulatory T cells Treg express TLR4/5/7/8, TLR signal directly involved in the biological function of TregB cell activation (eg: CpG DNA TLR9 ligands may be used as adjuvant).2-1

14、）RNA sensors（TLRs and RLRs）RIG-I Like Receptors（RLR）：RIG-IMDA-5LGP2。Fujita TNat Immunol. 2004 J Immunol 2005.2-2） structure of RIG-IRIG-I 結(jié)合 5-ppp dsRNA.MAVS： adapter for RIG-InSeth, R.B., Sun, L., Ea, C., and Chen, Z.J., Identification and characterization of MAVS: a mitochondrial antiviral signali

15、ng protein that activates NF-B and IRF3. Cell, 122:669-682, 2005 Prion-like protein fight off viruses: MAVS, Cell 2011University of Texas SouthwesternHHMI.2-3）RIG-1/MDA-5 signaling pathway.2-4） regulator of RIG-I/MDA-5 .Ubiquitin (泛素）對泛素）對PRR信號的調(diào)節(jié)信號的調(diào)節(jié)泛素由泛素由76個氨基酸殘基組成，其中包括個氨基酸殘基組成，其中包括7個賴氨酸殘基個賴氨酸殘基(

16、K), 其其C末端可與末端可與底物的賴氨酸殘基形成異肽鍵，從而引起底物的賴氨酸殘基形成異肽鍵，從而引起底物泛素化底物泛素化。泛素的。泛素的K11、K29、K48和和K63均能參與形成泛素與泛素間的異肽鍵均能參與形成泛素與泛素間的異肽鍵 (Isopeptide bond)。30.Ubiquitination for RIG-I signalingK63泛素化：激活K48泛素化：降解Back.3-1） DNA sensor DNA sensor： TLR9； Pol III； DAI； AIM2.4-1） NOD like receptors（NLRs）NLRs： C端：亮氨酸重復(fù)序列 （LRR）

17、中間：NACHT： 寡聚體化，活化N端：CARD，PYD：相互作用.4-2）NLRs activtes inflammasomePAMP通過NLRs激活炎癥反應(yīng).NLRC4 inflammasome 邵峰北京生命科學(xué)研究所Shao F. (2011) Nature, 477, 596600. .5-1）C-Lectin receptor familynDectin-1， Mannose Receptors （MRs）.5-2） The fungal pattern receptor： Dectin-1One such subfamily is the Dectin-1 clusterwhich

18、 is primarily, but not exclusively, expressed by myeloidcells macrophages, dendritic cells (DC) and neutrophils。.5-2） The fungal pattern receptor： Dectin-1Back.Dectin Signaling Pathway葡聚糖甘露聚糖甘露聚糖.6-2）other PRRsn清道夫受體（Scavenger receptors）: 結(jié)合脂類，LPS等n甲酸基多肽受體（Formyl peptide receptor)：結(jié)合含甲酸基的特殊氨基酸結(jié)構(gòu)n補(bǔ)體受

19、體（Complement receptor）：.Cross talk of PRR signaling.Cross talk of PRR signaling.Pathogen evasion of PRR signaling pathwayneg: HCV interact with PRRsFig1: structure of HCV.HCV interact with PRRs.Paper Discussion （1）： Role of TLR7 in WNV infection (Town T et al., 2009 Immunity; IF20)ssRNA dsRNA (durin

20、g replication) .Fig 1: Increased Susceptibility of Tlr7/ and Myd88/ Mice, but Not Tlr9/ Mice, after West Nile Virus ChallengeWT: 50%死亡TLR7-/-: 90%死亡TLR7 ：抗病毒作用.Fig 2. Tlr7- and Myd88-Dependent Viral Load and Innate Immune Cytokine Responses after West Nile Virus Challenge：Viral Load: Cytokine： IL23,

21、 IL12 .Fig 3：Immune Cell Homing to WNV-Infected Cells In Vivo depends on TLR7Green： WNV （More in TLR7 -/-）Red： Immune Cells (Less in TLR6 -/-).Immune Cell HomingHoming的意義：1、淋巴細(xì)胞得以合理的再分布及補(bǔ)充；2、增加抗原和淋巴細(xì)胞的接觸機(jī)會，產(chǎn)生有效的免疫應(yīng)答。(免疫細(xì)胞有效的遷移到受感染的部位)。.TLR7 dependant macrophage homingLess cell infiltration.Fig 4. Ma

22、crophage Homing to West Nile Virus Is IL-23 Signaling DependentMacrophageVirusHoming IssueBrain section staining.Summary: TLR7 mediated anti-WNV functionImmune Cell HomingVirus Clearance.Paper discussion (2): Caspase-12 controls West Nile virus infection Caspase-12 controls West Nile virus infection

23、 via the viral RNA receptor RIG-I. via the viral RNA receptor RIG-I. (Wang P. et al., Nature Immunology (Wang P. et al., Nature Immunology 2010)2010)Caspase 12 -/- :Less survival;Severe neurological symptoms.1) Viral load in Caspase 12-/- mice. 2) INFb production in Caspase12 -/- mice.3) Caspase12 i

24、nteracts with RIG-I/TRIM25. 4) Less Ub-RIG-I in Caspase 12-/- miceUb- RIG-I Total RIG-ITotal TRIM25.Story Summary: Caspase12 is required for RIG-I Ub IFNb production （Caspase 12 的抗病毒作用）Casp12eg: IFN production.Paper Discussion （3）： Toll-like receptor 3 mediates West Nile virus entry into the brain c

25、ausing lethal encephalitis （TLR3 helps the virus?）Wang T. et al., 2004 Nature MedicineWT: 0% survivalTLR3-/-: 40% survivalTLR3的存在 增強(qiáng)了病毒感染.2） TLR3-/- mice have viral load in blood; but TNFa, IL6.3) TLR3-/- have viral in brain （TLR3-/- 血液里virus多，但virus不能有效進(jìn)入大腦。）.4) Reduced brain tissue damage in TLR3-

26、/- mice炎性細(xì)胞滲入減少.5） BBB permeability increased in WT but in TLR3-/- mice after WNV infection 血腦屏障被打開血腦屏障相對完好Virus 難以進(jìn)入TLR3-/- 小鼠腦部。.6） TNFa is important for BBB breakdown1） TNFa -/-鼠，WNV感染死亡率下降2） IL6-/- 鼠，沒差異3）TNFa-/- 鼠， BBB保持相對完好TNFa是破壞BBB的細(xì)胞因子.Summary： TLR3 helps WNV enter the brain via TNFa* 免疫分子往

27、往是把雙刃劍血液- 大腦.Paper discussion 4: TLR and AgingJ Immunol. 2010 Mar 1;184(5):2518-27. Panda A, et al， Yale University School of Medicine Age-Age-associated decrease in associated decrease in TLR function in primary human dendritic cells predicts influenza vaccine function in primary human dendritic ce

28、lls predicts influenza vaccine response.response.Fig1. TLR expression in DCs.Fig 2. less cytokine production in old.Fig 3. Vaccine efficiency in young and old populationVaccine efficiencyYoungoldResponses to influenza vaccination in older adults and young adults.Paper 4 Summaryn1. Less TLR expressio

29、n in oldn2. TLR signaling are less responsive in oldn3. Defect of TLR signaling resulted in vaccine failure in old .Paper Discussion 5:DDX24 Negatively Regulates Cytosolic RNA-MediatedInnate Immune Signaling. DDX24 interact with FADD.IFN induce DDX24 expression.DDX24 inhibit IFN production.Silence D

30、DX24， IFN production increased.Figure 3 SiRNA-mediated knockdown of DDX24 enhances dsRNA induced RLR signaling.(G) Gene array indicating most up-regulated genes in MEFtreated with poly I:C at 3 hours and 9 hours VS non treatment. Data from (A)(B)(C)(D)(E)(F) are presented as means6s.e. from three independentexperiments. * indicates P,0.05. * indicates P,0.01.doi:10.1371/journal.ppat.1003721.g003.Figure 4. SiRNA-mediated knockdown of DDX24 inhibits VSV replication.Figure 4. SiRNA-mediated knockdown of DDX24 inhibits VSV replication.(F) Loss o