分子医学 感染免疫的分子机制与疾病A

分子医学（MolecularMedicine）炎症、感染与相关疾病

Infection感染Immunityisthebody’ssolutiontoprotectitselffromInfectiousDiseasesCommensalflora(共生菌群):staph,strep,pneumonia(葡萄球菌，链球菌，肺炎)Opportunisticpathogens(条件致病菌):candida,Clostridiumdifficile

(念珠菌，艰难梭状芽胞杆菌)Truepathogens(致病菌):InfluenzaContentsBriefintroductionofInfectiousDiseasesBacteriainfectionandInnateImmunityagainstbacteriainfectionViralinfectionandInnateImmunityagainstviralinfectionBriefintroductionofInfectiousDiseases1951年中国城市居民前10位死因:

肺炎;中枢神经系之血管病变;胃炎,十二指肠炎,肠炎及大肠炎;心脏疾病;恶性肿瘤;周产期之死因;结核病;意外灾祸;自杀及自伤;肾炎及肾水肿InfectiousdiseasesisstillamajorprimarycausesofdeathworldwideMorensDMetal.,Nature2004,430:242-9.Emergingandre-emerginginfectiousdiseasesMorensDMetal.,Nature2004,430:242-9.InnateimmunityagainstPathogenicMicrobes

Bacteria:

Virus

FungiBacteriaFACTS:largenumbersofsingle-celledprokaryotemicroorganisms.2.Typicallyafewmicrometersinlength;3.Everywhereinearth:water,soil,aswellasinlivebodiesofplantsandanimals4.10millioninagramofsoil;amillionin1Lwater,5×1030onearth;10timescellnumbersinhumanflora(菌群).BacteriaInfectionBacteriaFACTS:5.Thevastmajorityofthebacteriainthebodyarerenderedharmlessbytheprotectiveeffectsoftheimmunesystem,andafewarebeneficial.6.Afewspeciesofbacteriaarepathogenicandcauseinfectiousdiseases,includingcholera,syphilis,anthrax,leprosyandbubonicplague(霍乱，梅毒，炭疽，麻风病和鼠疫).Themostcommonfatalbacterialdiseasesarerespiratoryinfections,withturberculosisalonekillingabout2millionpeopleayear.7.Antibioticsareusedtotreatbacterialinfectionsandinagriculture,soantibioticresistanceisbecomingcommon.8.Inindustry,bacteriaareimportantinsewagetreatment,theproductionofcheeseandyogurtthroughfermentation,aswellasinbiotechnology,andthemanufactureofantibioticsandotherchemicals.Endotoxin:EndotoxinsaretoxinsassociatedwithcertainGram-negativebacteriawhicharestructuralmoleculesofthebacteriathatisrecognizedbytheimmunesystem.Theprototypicalexamplesofendotoxinarelipopolysaccharide(LPS).Exotoxin:Toxinsexcretedbyamicroorganism,includingbacteria,fungi,algaeandprotozoa.Anexotoxincancausedamagetothehostbydestroyingcellsordisruptingnormalcellularmetabolism.Theyarehighlypotentandcancausemajordamagetothehost.PathogenesisofBacteriaInfectionExotoxinsofBacteriaInfectionDiseasesfromBacteriaInfection固有免疫适应性免疫RecognitionOpsonization,phagocytosisDestructionMemoryInnateimmunity

Phagocytes Macrophages

Dendriticcells

Neutrophils

Receptors Toll-likereceptors C-typelectinreceptors

Cytosolic NODproteins RNAhelicases DNArecognition Mediators

InflamatorycytokinesAdaptiveimmunity

Humoral Antibodies Cellular TcellsMicrobialrecognitionininnateimmunereceptorsInvertebrates/VertebratesVertebratesRecognitionofMicrobeproductsbyPAMPSPathogen-associatedmolecularpatterns,orPAMPs,aremoleculesassociatedwithgroupsofpathogensrecognizedbycellsoftheinnateimmunesystem.Thesemoleculescanbereferredtoassmallmolecularmotifsconservedwithinaclassofmicrobes.Theyarerecognizedbypatternrecognitionreceptors(PRRs)likeToll-likereceptors(TLRs)inbothplantsandanimals.BacterialLipopolysaccharide(LPS)onbacterialcellmembrane(Gram-)Bbacterial

flagelinPeptidoglycanandlipoteichoicacid(磷脂壁酸)fromGrampositivebacteriaUnmethylated

CpGDNA。。。

PAMPsfrombacteriaToll-likereceptors(TLRs;transmembranereceptors)RIG-I-likereceptors(RLRs;cytoplasmicRNAhelicases)NOD-likereceptors(NLRs;cytoplasmicsensors)C-typelectinreceptors(CLRs;transmembranereceptors)Pattern

RecognitionReceptors（PRRs）Recognitionofpathogen-associatedmolecularpatternsbyPRRsDrosophilaTollIdentifiedaproteincalled“Toll”meaning“weird”HelpstheDrosophilaembryotodifferentiateitstopfromitsbottom

(Neuraltubedevelopment)http:///genomics/papers/drosophila.html

TollandInnerPartofHumanIL-1RisSimilarSearchingforproteinssimilartoTollShowscytoplasmicdomainofTollrelatedtothatofhIL-1RIdentityextendsfor135aaDidn’tmakesenseWhydoesaproteininvolvedinhumaninflammationlooklikeoneinvolvedinflyneuraltubedevelopment?FliesuseTolltoDefendfromFungiInfectedTl-deficientadultflieswithAspergillus

fumigatusAllfliesdiedafter2-3daysFliesuseTolltodefendfromfungiThus,inDrosophila,TollseemstobeinvolvedinembryonicdevelopmentandadultimmunitySurvivalrateofadultDrosophilainfected

withAspergillusfumigatusinToll-FliesuseTolltoDefendfromFungiDrosophilahasnoadaptiveimmunesystemThereforeneedsarapidantimicrobialpeptideresponseTwodistinctpathwaystoactivateantimicrobialpeptidegenesinadultsMutationsinTollpathwayreducesurvivalafterfungalinfectionHumanTollDiscoveryIninsect,IL-1receptorandtheTollproteinareonlysimilarinthesegmentswithinthecellhumanproteinsthattotallyresembletoTollwerelaterdiscoveredHumanTollDiscoveryAlignmentofthesequencesofhumanandDrosophilaTollproteinsHomologyovertheentirelengthoftheproteinchainshTollgenemoststronglyexpressedinSpleenandPBL(peripheralbloodleukocytes)TLRs:Toll-likeReceptorsdiacyl-triacyl-lipopeptide

酰基脂肽；flagellin:鞭毛蛋白;LPS:脂多糖(Lipopolysaccharides)

LPSistheligandforTLR4LargemoleculesfoundinoutermembraneofGram-negativebacteriaComprisedofalipidandsaccharidecomponentHighlyimmunogenicRecognizedbyTLR4CancausesepticshockandleadtodeathOftenreferredtoasEndotoxinsinceitisnotsecretedbutisabyproductofbacteriallysisTLR4ActivatedbyLPSNormalmicedieofsepsisafterbeinginjectedwithLPSC3H/HeJmicehavedefectiveresponsetoLPSandsurviveMissensemutationaffectingthecytoplasmicdomainofTLR4Majorbreakthroughinthefieldofsepsis–molecularmechanismthatunderliesinflammationrevealedLPSLPS/nobel_prizes/medicine/laureates/2011/#TLRs:StructureLigandRecognitionTLR3-dsRNALigandRecognitionTLR4/MD2–LPSMyD88-dependentandindependentpathway

CytoplasmictailsofTLRsshowsimilaritiestoIL-1receptor(TIR)CommonadaptortoTLRsisMyD88CrucialprolineresidueinallTLRTIRdomains,exceptTLR3Ifmutatedordeleted,nosignalingoccursAllTLRslikelyhaveaMyD88pathway(TLR3isanexception)TLR4hasaMyD88independentpathwayaswellCytoplasmicTIRdomainTLRsandTIRDomainMyD88knockoutmicehavenoresponsetoLPSMyD88isessentialtoallinflammatorysignalingpathwaysMyD88s,asplicevariantofMyD88downregulatestheinflammatoryresponseMyD88interactswithTIRdomainofTLRandrecruitsIRAK-4,IRAK-1andTRAF-6MyD88AdaptorRakoff-Nahoumetal.,Recognitionofcommensal

microflorabyToll-likereceptorsisrequiredforintestinalhomestasis.Cell118:229-41,2004.4IRAKsknown,IRAK1,IRAK-2,IRAK-MandIRAK-4IRAKareserine/threonine

kinasesIRAK-4phosphorylatesIRAK-1IRAK-MplaysaninhibitoryroleinTLRsignalingTRAF6isamemberoftheTNFreceptorassociatedfactor(TRAF)familyTRAF6interactswithIRAK-1andgetsactivatedReleaseofTRAF6/IRAK-1ensuessubsequentsignalingIRAKandTRAF6IL-1RI-associatedproteinkinases(IRAKs)tumornecrosisfactorreceptor-associatedfactor6(TRAF6).TRAF6/IRAK-1complexassociateswith3proteinsTAK1(TGF-Bactivatedkinase)TAB1(TAK1bindingproteins)TAB2(TAK1bindingproteins)LargecomplexassociateswithmembraneEventuallyIRAK-1staysinmembranewhileTRAF6/TAK1/TAB1/TAB2movetocytosolE2LigasessuchasUbc13andUev1AjoinfurtherenlargingcomplexIRAKandTRAF6ReleaseTAK-1ActivationTheenlargedcomplexthatincludesTRAF6,TAK1,TAB1,TAB2,Ubc13,Uev1AactivateTAK1ActivatedTAK1phosphorylatesIKKcomplexActivatedTAK1canalsophosphorylateMAPKinases

IKKcomplexconsistsofIKK,and/NEMOIBphosphorylationresultsinNF-BtranslocationtonucleusOverviewofMyD88-dependentpathwayMyD88IndependentPathwayMyD88KnockoutmicedonotproduceinflammatorycytokinessuchasTNF-

HoweverwithTLR4stimulationNF-BandJNKdelayedactivityoccursThisstronglysuggeststheexistenceof2pathwaysinTLRsignalingaMyD88dependentpathwayaMyD88independentpathwayTLR3stimulationalsoexchibitsaMyD88independentpathwayTLR4OverviewofTLRsignalingInflammationCytokinesChemokinesFluidsProteinsBacteriatriggermacrophagestoreleasecytokinesandchemokinesVasodilationandincreasedvascularpremeabilitycauseredness,heat,andswellingInflammatorycellsmigrateintotissue,releasinginflammatorymediatorsthatcausepainInflammationInflammationispartofthecomplexbiologicalresponseofvasculartissuestoharmfulstimuli,suchaspathogens,damagedcells,orirritants.Inflammationisaprotectiveattemptbytheorganismtoremovetheinjuriousstimuliandtoinitiatethehealingprocess.FourMajorSymptomsofInflammation:1.Redness2.Pain3.Heat4.SwellingMayalsoobserve:5.LossoffunctionFunctionsofInflammationDestroyandremovepathogens(aswellasdamagedselftissuesandcells).Ifdestructionisnotpossible,tolimiteffectsbyconfiningthepathogenanditsproducts.Repairandreplacetissuedamagedbypathogenanditsproducts.InflammationmediatedbycytokinesLowmolecularweight,solubleproteinsthatareproducedinresponsetoanantigenandfunctionaschemicalmessengersforregulatingtheinnateandadaptiveimmunesystemInnateimmunesystemMacrophagesandDendriticcellsTumornecrosisfactor-alpha(TNF-)Interleukin-1(IL-1)Interleukin-12(IL-12)Adaptiveimmunesystem……………InflammationPro-inflammatorycytokines(TNF,IL-1)signaltoendothelialcellstomakethem:Leakytofluid(influxofplasma;containingantibodies,complementcomponents,etc.)Stickyforleukocytes,leadingtoinfluxofneutrophilsfirst,thenmonocytes,lymphocytesSystemiceffects:fever,acutephaseresponseSepsis(Septicshock)BacterialsepticemialeadstoactivationofTLRsonmonocytesinthebloodSystemicreleaseofTNFandIL-1leadsto“inflammation”alloverthebodyShockfromlossofbloodpressure(vasodilationandleakageoffluidintotissues)Thecombinationofeffectscanleadtomulti-organfailureanddeathBacteriaInfectionafterinjury—SepsisinEmergencyRoomNeonatalSepsisNegativeRegulationofToll-likereceptorsignalingSolubleTLRsMembrane-associatedRegulatorsFeedbackRegulationofIntracellularsignalingNLRTheNOD-likereceptors(NLRs)arecytoplasmicproteinsthathaveavarietyoffunctionsinregulationofinflammatoryandapoptoticresponses;TheofficialdefinitionofNLRiscurrently"Nucleotide-bindingdomain,Leucine-Richrepeatcontaining"proteinsincetheseproteinsarecomposedofconserved"modules"includingacentralnucleotide-bindingoligomerizationdomainandaseriesoftandemleucine-richrepeats.NLRsareencodedbyalargegenefamiliesinmanydifferentanimalspecies;therearemorethan20NLRgenesinhumans.Manyarethoughttoserveaspatternrecognitionreceptors(PRRs)whichsensemicrobialproductsinthecytoplasmofcells,althoughsomemembershavedifferentfunctions.NOD1&NOD2recognizepeptidoglycansubstructuresandpromoteinnateimmuneresponsesNOD1andNOD2areintracellularmoleculesandresemblesomeplantdiseaseresistanceproteins;bestunderstoodofthe“NOD-likereceptors”orNLRs

NLR

signalingCARD

Domains：CaspaserecruitmentdomainsProcessingofIL-1andrelatedcytokinesbyinflammasome:animportantregulatorystepSome“NLRs”assembletoformthe“inflammasome”whichproteolyticallyprocessesIL-1andrelatedcytokinestotheiractive,secretedforms.InflammasomeinactivatedbycellularstressorrecognitionofmicrobialcomponentsinthecytoplasmGeneticperiodicfeversyndromesareduetoactivatingmutationsininflammasomeNOD-likereceptor(NLR)familymemberssuchasNALPs,NAIP,andIPAFTheLRRofNALP3orIPAFsensetheactivatingsignalsleadingtotheoligomerization

oftheNACHTregion.TheexposedPYDandCARDdomaincanrecruitadaptorproteinASCandCARD-containingcaspasestoformadonutshapecomplex.TheIL-1β-processingcaspaseactivitymostlikelyfacetheinsideofthedonut(lowerpanel).NACHTPYDCARDTwo

signalsareessentialforIL-1secretionInnateImmunityagainstViralinfectionViralinfection:Avirusisasmallinfectiousagentthatcanreplicateonlyinsidethelivingcellsoforganisms.EntrymediatedbyCellsurfaceReceptors:ViralInfectionVirus

receptor

celltypeHIV CD4 ThcellsEBV CR2 BcellsInfluenza sialicacid manycelltypesRhinovirus ICAM-1 manycelltypesPoliovirus poliovirusreceptor neuronsMeasles CD46 manycelltypesHHV6 CD46 manycelltypes GeneralProcessofViralInfection:ViralInfectionAttachmentPenetrationUncoatingReplicationself-assemblyReleaseCelldamagesmediatedbyviralinfection-EffectsonthehostcellMostvirusinfectionseventuallyresultinthedeathofthehostcell.Thecausesofdeathincludecelllysisandapoptosis。Oftencelldeathiscausedbycessationofitsnormalactivitiesbecauseofsuppressionbyvirus-specificproteinsSomevirusescausenoapparentchangestotheinfectedcell（latentinfection）.Thiscausespersistentinfectionsandthevirusisoftendormantformanymonthsoryears.Thisisoftenthecasewithherpesviruses.Someviruses,suchasEpstein-Barrvirus,cancausecellstoproliferatewithoutcausingmalignancy,whileothers,suchas,papilloma

viruses(HPV

乳头状瘤病毒)areestablishedcausesofcancer.ViralInfectionViralInfectionViralNucleicAcidsrecognizedbyTLRsViralNucleicAcidsrecognizedbyTLRsRecognitionofcytosolicviralRNAsbyRLRsRIG-I-likereceptors(RLRs),alsoknownasRIG-I-likehelicases(RLHs)constituteafamilyofcytoplasmicRNAhelicasesthatarecriticalforhostantiviralresponses.

RIG-I(retinoic-acid-inducibleprotein1,alsoknownasDdx58)andMDA-5(melanoma-differentiation-associatedgene5,alsoknownasIfih1orHelicard)sensedouble-strandedRNA(dsRNA),areplicationintermediateforRNAviruses,leadingtoproductionoftypeIinterferons(IFNs)ininfectedcells.

RIG-IandMDA-5containaDExD/HboxRNAhelicaseandtwocaspaserecruitingdomain(CARD)-likedomains.ThehelicasedomaininteractswithdsRNA,whereastheCARDdomainsarerequiredtorelaythesignal.

RIG-IparticipatesintherecognitionofParamyxoviruses(Newcastlediseasevirus(NDV),Sendaivirus(SeV)),Rhabdoviruses(vesicularstomatitisvirus(VSV)),Flaviviruses(hepatitisC(HCV))andOrthomyxoviruses(Influenza).MDA-5isessentialfortherecognitionofPicornaviruses(encephalo-myocarditisvirus(EMCV))andpoly(I:C),asyntheticanalogofviraldsRNA.

Notably,RIG-IbindsspecificallytosinglestrandedRNAcontaining5’-triphosphatesuchasviralRNAandinvitro-transcribedlongdsRNA[4].MammalianRNAiseithercappedorcontainsbasemodificationssuggestingthatRIG-Iisabletodiscriminatebetweenselfandnon-selfRNA.RIG-IbindspreferentiallytoshortdsRNAwhileMDA-5recognizespreferentiallylongdsRNA.ViraldsRNAisalsorecognizedbyToll-Likereceptor3(TLR3)whichisexpressedonthecellsurfacemembraneorendosomes.

RecognitionofdsRNAbyRIG-I/MDA-5orTLR3iscell-typedependent.StudiesofRIG-I-andMDA-5-deficientmicehaverevealedthatconventionaldendriticcells(DCs),macrophagesandfibroblastsisolatedfromthesemicehaveimpairedIFNinductionafterRNAvirusinfection,whileproductionofIFNisstillobservedinplasmacytoid

DCs(pDCs).ThusincDCs,macrophagesandfibroblasts,RLRsarethemajorsensorsforviralinfection,whileinpDCs,TLRsplayamoreimportantrole.RLRs

vsTLR31.IFNisinducedbyviralinfection.2.IFNbindstospecificcellsurfacereceptorsandactivateintracellularsignalingpathways.3.IFNsign