Post on 11-Dec-2021
Lemalattiepossonoesserestudiateadiversilivelli
epidemiologia
singolipazienti
fisiopatologia
istopatologia
fisiopatologiacellulare
citopatologia
patologiamolecolare
biologiamolecolare
thepresenceorabsenceofa protein or RNA, or anincrease ordecrease in theamount/activity of thesemolecules
rearrangementsoflargeportionsofDNA(translocations) or specific changes ingenestructure(mutations)
✓ Moleculartestscanbeusedtodiagnoseagivendisease:
Molecularpathology
infections by certain viruses(cytomegalovirus and EBV) canbe diagnosed by moleculartesting for the presence of theirspecificRNAsinblood
in the field of cancer pathology,the demonstration of a specificgene mutation or rearrangementcan help confirm the diagnosis ofcertainlymphomasandsarcomas
✓ Moleculartestscanbeusedtosearchthecauseofagivendisease:
✓ Moleculartestscanhelpwiththeprevention….
Molecularpathology
tests that look for inheritedgeneticdiseaseallowforpreventivemeasurestobegiventothetestedpatientsand/or their relatives; (forex.,colorectalcancerpatientscanbetestedforthepresenceofinheritedmutationsingenessuchasAPC)
new generationdrugs can specifically target crucial sitesofmolecules involved in thepathogeneticmechanism(s)ofadisease
…..andtreatmentofadiseaseinseveralways:
● Examplesoftherapeutictreatmenttargetingpathogeneticmechanismsatmolecularlevels:
➢acutelymphoblasticleukemia(ALL)
➢chronicmyeloidleukemia(CML)
➢rheumatoidarthritis(RA)
Molecularpathology
Acutelymphoblasticleukemia(ALL)
• Janus kinases, JAKs, are abundantly expressed inleukemic cells of childrenwith ALL themost commonformofchildhoodcancer
• recentstudieshavecorrelatedJAKactivity inALLcellswithsignalsdown-regulatingapoptosis
• apoptosisdefect contribute to increase thenumberofproliferatingleukemiccell
A,modelof JAK3showingmolecular surfaceofprotein (blue)andcatalytic (ATP-binding)site(yellow).B,ribbonrepresentationofJAK3kinasedomain.Theinhibitor moleculeisshownasaspace-fillingmodelinthecatalyticsiteofJAK3.C,close-upviewofcatalyticsiteofJAK3modelwithdockedinhibitor(green).
Structure-basedDesignof Specific Inhibitorsof JanusKinase3asApoptosis-inducingAntileukemicAgents
IlcromosomaPhiladelphianellaleucemiamieloidecronica
Il gene di fusione ABL-BCR produce una proteina adattività tirosin chinasica che non risponde più ainormalicontrolli(lossofnegativeregulatorydomains)
Molecularpathogenesisofchronicmyeloidleukemia
1960: 22Ph’ identified
1845: CML described
1986: BCR-ABL identfied
1973: t(9:22) identified
1998: BCR-ABL inhibitor tested in CML patients
2001: Gleevec (Imatinib) approved by FDA
Milestones of CML research
TrattamentodellaleucemiamieloidecronicaIlfarmacoagisceinibendol’attivitàtirosinchinasicadi bcr-abl: “congela” la proteina nella suaconformazioneinattivaincapacedilegarel’ATP
● elevataefficacia● bassatossicità
Firsthumantrialin1998:thisdrugrestorednormalbloodcountsinall31treatedpatients
Rheumatoid arthritis (RA) is a systemic, chronicinflammatory autoimmune disease affecting manytissuesbutprincipallyattackingthejoints.
mildform aggressiveform
Inflammation:keynotes
●Protective response involving various host bloodvessels,cells,proteinsandothermediators
● Intendedtoeliminate the initial causeofcell injury,aswellasthenecroticcellsandtissuesresultingfromtheoriginalinsult,andtoinitiatetheprocessofrepair
●Maintained under strict control to minimize tissuedamage
● The inflammatory reaction and the subsequent repair processcanthemselvescauseconsiderableharm
● Inflammatorydamagemayevenbecomethedominantfeatureifthereactionis:● verystrong(e.g.,whentheinfectionissevere)
● prolonged(e.g.,whentheelicitingagentresistseradication)
● inappropriate(e.g.,whenitisdirectedagainstself-antigens,suchasinautoimmunediseases)
● excessive (e.g., inallergicdisordersagainstusuallyharmlessenvironmentalantigens)
Inflammation:keynotes
Examplesofhumanpathologiesassociatedwithinflammation
● Infections(bacterial,viral,fungal,parasitic)
● Traumaandtissuedamagebyphysicalandchemicalagents
● Immunereactions
● Tissuenecrosis
● Hemodynamicdisorders(atherosclerosis,thrombosis)
● Neoplasia
Inflammation: the «backbone» of pathology (Lord Howard Florey, 1945 Nobel Prize for Medicine)
• These two basic formsof inflammationmay coexist, andmany variables modify their course and histologicappearance
• Chronic inflammation can have serious pathologicconsequences
Inflammation:keynotes
Thecomponentsofacuteandchronicinflammatoryresponsesandtheirprincipalfunctions:anintegratedview
Inflammation:keynotes
Recognition of the INFLAMMATORY STIMULUS
RELEASE OF MEDIATORS
vascular changes
Protein and cell recruitment into tissues
Main events in acute inflammation
formation of the inflammatory exudate
● Vertebrates evolved two different systems to recognize andeliminatepathogens:theinnate(natural)andadaptive(acquired)immunity
● Theinnateimmunesystemisthefirstonetobeactivatedandcansense a wide range of pathogenic microbes through a limitednumberofreceptors,calledpattern-recognitionreceptors(PRRs)
● PRRs are expressed by many cell types (mainly macrophages,monocytes,neutrophils,dendriticcells),allowingthedetectionofpathogenstotakeplacedirectlyatthesiteofinfection
● Inaddition to recognize infectiouspathogens,PRRs aredesignedtosensethepresenceofsubstancesreleasedfromdeadcells
Phase1:recognitionofmicrobesandnecroticcells
Phase1:recognitionofmicrobesandnecroticcells
● Microbes and necrotic cells elicit “danger signals” thatdistinguish them from normal tissues and mobilize the hostresponse
● PRRsrecognizestructures(i.e.,molecularpatterns)commonto:
➢manymicrobes(Pathogen-AssociatedMolecularPatterns,PAMPs)
➢deadcells(Damage-AssociatedMolecularPatterns,DAMPs)
● OnceactivatedbyPRRs–PAMPs interaction, thecellsof theinnate immunesysteminitiatestheinflammatoryresponsebysecretingcytokinesandchemokines
● This leads to the expression of adhesion and co-stimulatorymolecules able to (1) recruit immune cells and (2) stimulatetheadaptiveimmuneresponse
● Because of the need todistinguish between pathogenic andnon-pathogenic (or commensal) microbes, it has beenproposed that the innate immune system is activated by therecognition of an antigen, but only in presence of dangersignalsreleasedbycells(DAMPs).
Phase1:recognitionofmicrobesandnecroticcells
Damage-AssociatedMolecularPatterns
●DAMPs:[allarmins]
● intracellularproteins,suchasheat-shockproteins(HSP)orHMGB1(high-mobilitygroupbox1),Ca++bindingproteins
● non-proteinDAMPs:ATP,uricacid,DNA,RNA,alteredphospholipids
● proteinsderivedfromtheextracellularmatrixgeneratedupontissueinjury,suchashyaluronanfragments
Summaryofmolecularinteractionsinvolvedintherecognitionofpathogensand/orsubstancesreleasedbynecroticcells
Patternrecognitionreceptors(PRRs)
Damage-associatedmolecularpatterns(DAMPs;allarmins)
Pathogen-associatedmolecularpatterns
(PAMPs)
Toll-likereceptors(TLRs)
NOD-likereceptors(NLRs)
PRRsrecognizepathogen-associatedmolecularpatterns(PAMPs)fromdifferentclassesofpathogens
Viruses, bacteria, fungi, and protozoa display several different PAMPs,someofwhicharesharedbydifferentclassesofpathogens.MajorPAMPsare nucleic acids, surface glycoproteins (GP), lipoproteins (LP), andmembranecomponents[peptidoglycans(PG),lipoteichoicacid(LTA),LPS].PAMPsarerecognizedbydifferentfamiliesofPRRs.
PRRs:PatternRecognitionReceptors➢Toll-like receptors (TLRs): (ten types)microbial sensorslocated in plasma membranes and endosomes; detectextracellularandingestedmicrobes
➢TLRs recognize products of different types of microbes;providedefenseagainstessentiallyallclassesofpathogens
➢Recognition of microbes by these receptors activatestranscription factors that stimulate the production of anumber of secreted and membrane proteins such as:mediators of inflammation, antiviral cytokines (interferons),andproteinsthatpromotelymphocyteactivation
TenhumanTLRsandtheirpathways
SignalingpathwaysactivatedbyTLRsmightbeMyD88dependentorindependent.
MyD88(myeloiddifferentiationfactor88)isanadaptormoleculethatrecruits and activates other proteins that partake to the signalingcascade; resulting in the activation ofNF-κB and other transcriptionfactors(CREBandAP1).
• The activation of both the MyD88-dependent and MyD88-independent pathway finally leads to synthesis of inflammatorycytokinesoranti-viraltypeIinterferons(α-,β-IFNs).
• AllTLRs,exceptTLR3,canactivateMyD88.
http://www.intechopen.com/books/major-topics-in-type-1-diabetes/the-innate-immune-system-via-toll-like-receptors-tlrs-in-type-1-diabetes-mechanistic-insights
LEGENDADELLASLIDEPRECEDENTE
• Afterrecognizingamoleculeonthemicrobe,theTLRsbeginaseries of chemical reactions that activate the innate immunecellandallowittofunctioninthekillingofmicrobes
• If oneormoreof these signalingmoleculesaredefective, theinnateimmunecellcannotkillthemicrobe
• In recent years several deficiencies of TLRs have beenidentifiedinpatientswhopresentwithrecurrentinfections
• The knowledgeof the functionof these TLRshasprovidedanimportant basis for the diagnosis and treatment of thesedisorders
Toll-like Receptors
Examples of TLRs defects will be treated later in the section«Immunodeficiencies»
PRRsrecognizepathogen-associatedmolecularpatterns(PAMPs)fromdifferentclassesofpathogens
Viruses, bacteria, fungi, and protozoa display several different PAMPs,someofwhichare sharedbetweendifferent classesofpathogens.MajorPAMPsarenucleicacids,surfaceglycoproteins(GP), lipoproteins(LP),andmembranecomponents[peptidoglycans(PG),lipoteichoicacid(LTA),LPS].PAMPsarerecognizedbydifferentfamiliesofPRRs.
NLRs=NOD-likereceptorsnucleotide-bindingoligomerizationdomain-likereceptors
NOD-likereceptors(NLRs):Nucleotide-bindingoligomerizationdomain-likeRs
●The NOD-like receptors (NLRs) are a family of PRRsmostlyexpressed inthecytosolandthereforeabletodetectsignsofintracellularinvaders
●SomeoftheNLRscanalsosensenon-microbialdangersignals and form large cytoplasmic complexes calledinflammasomes
●The inflammasome: multi-protein cytoplasmic complex thatrecognizesproductsofdeadcells,suchasuricacidandextracellularATP,aswellaspathologiccrystals(urateandcholesterolcrystals)andsomemicrobialproducts
● Triggering of the inflammasome results inactivation of an enzymecalledcaspase-1,whichcleavesprecursorformsoftheinflammatorycytokineIL-1βintoitsbiologicallyactiveform
● In the inflammatory response, IL-1β mediates the activation ofendothelial cell and the recruitment of leukocytes whichphagocytoseanddestroymicrobesanddeadcells
PRRs:PatternRecognitionReceptors
Somepeculiaraspectsoftheinflammasomewillbetreatedlaterinthesection«Inflammatoryboweldiseases»