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2ND SEMINARBASIC CONCEPTS OF INNATE IMMUNITY,INFLAMMATION

SinusesTracheaLungsAIRWAY SYSTEMEYEOral cavityEsophagusStomachAlimentary tractGASTROINTESTINAL SYSTEMDAMAGE TO ANY OF THESE BARRIERS MAY LEAD TO INFECTIONKidneyBladderVaginaUROGENITAL SYSTEMWALDEYER RINGTonsils, adenoidsPalatinal, pharyngeal lingual and tubar tonsilsSKINCONTACT SURFACESPhysical, chemical, microbiological barriersChange figure2

FIRST LINE OF DEFENSE3PHYSICAL, CHEMICAL AND MICROBIOLOGICAL BARRIERSGI tractStomach: pH of 3-4; small intestine: pH of 6-8Digestive enzymesMucusAntibacterial peptides e.g. defensins, cryptidinsPeristalsis, diarrhoea, vomitingNormal floraH. pylori making basic pH

SkinTight junctionsKeratin layerAntibacterial peptides e.g. defensinspH of 5.5Fatty acidsNormal floraBurns susceptibility to infections

EyeTear film (oils, lactoferrin, mucin and lysozyme)

Urogenital tractFlushing outVagina: pH of 3.8-4.5, normal flora (Lactobacillus lactic acid)Respiratory tractCiliary movement constant outward flowCoughing, sneezingCF - impaired cilia movement

Defensins: highly positively charged, forming pores in bacterial membranes. Have an anti-viral activity as well. 4

The normal flora

SKIN, NASO-ORO-PHARYNGS, GUT, VAGINA Symbiotic, non-pathogenic microbes, living in peaceful commensalisms

Beneficial features:

Digesting non absorbable food compounds e.g. cellulose Producing vitamines, antimicrobial molecules, regulating pH Compete with pathogenic microbes survival of the fittest Providing constant low-dose antigen exposure Helping the development of the immune system Maintainig tolerance

MICROBIOLOGICAL BARRIERSSome facts about the normal flora:

There are 100-times more bacterial genes than eukaryotic genesCells of human body: 90% microbes, 10% humanGut bacteria: 1014 - more than 500 microbial species (approx. 1.5 kgs)Human cell population: 1013

BALANCE!(antibiotics probiotics)

Gut normal flora play an important role in:Development of mucosal and systemic immunityNormal development of peripheral lymphoid organs- Maintenance of basic level of immunity

DCEpithelial cellsPERIFRIS SZVETEKStroma cellsTISSUESPECIFIC CELLULAR COMMUNICATION NETWORKS

Granulocyte

MacrophageNK cell NKT cellDendritic cellORGANIZATION OF IMMUNE CELLS UNDER EPITHELIAL SURFACESRECOGNITION

BY THE INNATE IMMUNE SYSTEMSENSINGRECOGNITIONSIGNALINGRESPONSEINNATE IMMUNITYCellsReceptorsSignaling pathwaysCell-Cell collaborationEffector functionsDEFENSE SYSTEMSADAPTIVE IMMUNITYSENSINGRECOGNITIONSIGNALINGRESPONSERECOGNITION RECEPTORS OF INNATE IMMUNITYPattern Recognition Receptors (PRRs)

recognise molecular patterns as danger signalscan be classified as PRR families:LectinsToll-Like Receptors (TLRs)Nod-Like Receptors (NLRs)RIG-Like Receptors (RLRs)Scavenger receptors

molecular pattern: characteristic molecules that are expressed in high amounts by cells or microbes

Patogen-Associated Molecular Patterns (PAMPs): molecules that are expressed unlike human cells, usually essential for the survival or replication of pathogensDamage-Assoiated Molecular Patterns (DAMPs): molecules released after cellular damage

TOLL-LIKE RECEPTOR FAMILY

Conventional DCPlasmacytoid DC58737109NLRIL-1IL-12/23IL-10IFNIFN124616RLRRLRDANGER SIGNALS ARE TRANSLATED TO CYTOKINE SECRETION THROUGH VARIOUS MOLECULAR SENSORS IN DC SUBTYPESTLR1 bacterial lipoprotein (together with TLR2)TLR2 bacterial lipoprotein, peptidoglycane, lipoteicholic acid (heteromer with TLR1 and TLR6)TLR3 viral dsRNATLR4 bacterial LPSTLR5 bacterial flagellinTLR6 bacterial lipoprotein (together with TLR2)TLR7 viral ssRNATLR8 viral ssRNATLR9 unmethylated CpG DNATLR10 modified viral nucleotidesNLRs microbial products, DAMPsRLRs viral ssRNA

EFFECTOR MECHANISMS OF INNATE IMMUNITYKILLER CELLSPHAGOCYTIC CELLSCOMPLEMENT SYSTEM

PHAGOCYTIC SYSTEMNEUTROPHIL - MACROPHAGE - DENDRITIC CELLDefense against infectious diseasesElimination of tumor cellsTransplantation rejectionGatekeeper functionSensing commensals and pathogensRapid activation of innate immunityPriming adaptive immune responsesMaintenance of self-tolerance

RECEPTORS ON MACROPHAGESTLR4 + CD14MHCIMHCIITLRs PAMPsCR1 (CD35)CR3 (CD11b/CD18)LFA1 (CD11a/CD18)FcRIII (CD16)FcRII (CD32)FcRI (CD64)Ag + Ab complex

Mannose receptorScavanger receptorComplement receptorsCell adhesion moleculesMannoseEukaryotic cellsGlucoseaminMannoseGalactoseSialic acidGLYCOSYLATION OF PROTEINS IS DIFFERENT IN VARIOUS SPECIESProkaryotic cellsMacrophage/dendritic cellsMannose ReceptorMannoseMANNOSE RECEPTORS ON PHAGOCYTESBacteriumPHAGOCYTOSIS, RECOGNITION RECEPTORS, SIGNAL TRANSDUCTION, EFFECTOR MECHANISM

Pattern recognitionReceptors (PRR)Engagement of PRR triggers phagocytosis and cytokine productionUPTAKEMacropinocytosisReceptor-mediated endocytosisPhagocytosis

COLLECTION OF ENVIRONMENTAL INFORMATONLectins: receptors ( or plasma proteins) that bind to carbohydrates. On macrophages one finds mannose rec. And glucan receptors. Scavenger receptor binds various substrates generally negatively charges (sulfated polysaccharides, nucleic acids, lipoteic acid bound in the cell wall of Gram positive bacteria)18

PHAGOCYTOSIS

INNATE IMMUNITYPathogen recognition PRRs (TLRs, lectins, NLRs, RLRs, scavenger receptors)

Cell activation Increased phagocytic activity, intracellular killing (reactive oxygen species (ROS), lysosomal enzymes), chemokine and cytokine secretion

Antigen processing Phagocytosis/endocytosis degradation in phagolysosomes

Antigen presentation (later)ACUTE INFLAMMATION&ACUTE-PHASE RESPONSE ACUTE INFLAMMATION

A rapid response to an injurious agent that serves to deliver leukocytes and plasma proteins to the site of injury

InfectionsTraumaPhysical and Chemical agents (thermal injury, irradiation, chemicals)Tissue NecrosisForeign bodies (splinters, dirt, sutures)Hypersensitivity or autoimmune reactionsVascular response:

Increased vascular diameter Increased flood flow.Endothelial cell activationincreased permeability that permits plasma proteins and leukocytes to leave the circulation and enter the tissue edemaincreased expression of cell adhesion molecules e.g. E-selectin, ICAM

Cellular response:

Migration of leukocytes (diapedesis/extravasation), accumulation, effector functionsMAJOR COMPONENTS OF INFLAMMATION:TRIGGERS OF ACUTE INFLAMMATION:

THE CLASSIC SYMPTOMS OF INFLAMMATION:

Redness (rubor) Swelling (tumor) Heat (calor) Pain (dolor)Loss of function (functio laesa)

You ought to know which classic symptom is caused by which pathophysiological process25

Resident phagocytes get activated by PRR signalization upon recognition of danger signals Production of cytokines and chemokines, Intracellular killing, Antigen presentation (activation of adaptive responses)

ORDER OF INNATE CELLS APPEARANCE IN THE INFLAMED SITE

NEUTROPHIL GRANULOCYTES68% of circulating leukocytes, 99% of circulating granulocytesPhagocytic cellsAre not present in healthy tissuesMigration elimination of pathogens (enzymes, reactive oxygen intermediates) Main participants in acute inflammatory processes

28LFA-1: Lymphocyte-function associated antigen-1Sialylated Lewis X Ag

NEUTROPHIL CHEMOTAXIS29acPGP: N-acetyl Proline-Glycine-Proline neutrophil chemoattractantMMP: matrix metalloproteinaseMIGRATION OF NEUTROPHILS

Neutrophil Transendothelial Migration (Diapedesis)Pathogens activate macrophages to release cytokines and are then phagocytized and digested in phagolysosomes

Local effect & systemic effectCHEMICAL MEDIATORSVasodilationProstaglandins (PG), nitric oxide (NO)Increased vascular permeabilityvasoactive amines (histamine, serotonin), C3a and C5a (complement system), bradykinin, leukotrienes (LT), PAF Chemotactic leukocyte activationC3a, C5a, LTB4, chemokines (e.g. IL-8)FeverIL-1, IL-6, TNF, PGE2PainProstaglandins, bradykininTissue damageNeutrophil and Macrophage productslysosomal enzymesReactive oxygen species (ROS)NOCHEMICAL MEDIATORSNSAIDs and Paracetamol:inhibiting COX-1 and COX-2 preventing the synthesis of prostaglandins35

During an APR their concentration increases up to x1000 ACUTE-PHASE RESPONSE PROTEINSPentraxin family:CRP opsonization, complement activationSAP opsonization, complement activation, binding of mannose/galactose

Collectin family:SP-A/D collectins of lungsMBL part of complement system

Complement proteins (C1-C9)

Fibrinogen blood clotting SP-A/D: Surfactant Protein A and D36

RESOLUTION OF ACUTE INFLAMMATION