Injury, inflammation, healing and repair. Markéta Hermanová General features of inflammation nA benefitial host response to foreign invadors and necrotic tissue; but itself capable of causing tissue damage n nMain component of inflammation: vascular reaction (vascular and exudative phase) and a cellular response (activated by mediators of inflammation derived from plasma protein and various cells) n nInflammatory response (5 Rs): -Recognition of the injurious agent -Recruitment of leukocytes -Removal of the agent -Regulation of the response -Resolution (repair) n nOutcome of acute inflammation: -Elimination of the noxious stimulus, decline of the reaction, resolution-repair -Persistent injury resulting in chronic inflammation -Extensive destruction of the tissue resulting in scarring Acute inflammation: rapid response to injury or microbes and other foreign substances nStimuli for acute inflamation: nInfections (bacterial, viral, fungal, parasitic) nTrauma and physical and chemical agents nTissue necrosis (e.g. ischamic infarctions) nForeign bodies nImmune reactions (=hypersensitivity reactions) against environmental substances or against self tissues → immune-mediated inflammatory disease Macroscopis appearance of acute inflammation (Celsus signs) nRedness (rubor) nHeat (calor) nSwelling (tumor) nPain (dolor) nLoss of function (function laesa) Early stages of acute inflammation nChanges in vascular caliber and flow -vasodilatation – induced by chemical mediators (e.g. histamin) – causes erythema and stasis n nIncreased vascular permeability and formation of the protein rich fluid exudate -induced by histamine, kinins, … → gaps between endothelial cells (by direct or leukocyte induced injury, by increased passage through the epithelium) n nFormation of the cellular exudate -Leukocytes recruited from the blood into extravascular tissues – migrate to the site of infection or tissue injury – are activated to perform their functions -Neutrophils predominate in the early inflammatory infiltrate and are later replaced by macrophages n nResponses of lymphatic vessels n- increased lymph flow; secondary (reactive) lymphangitis, lymphadenitits n extravasation_of_leukocytes Leukocyte effector function nLeukocytes eliminate microbes and dead cells by phagocytosis (with destruction on phagolysosomes) n nDestruction caused by free radicals (ROS, NO) generated in activated leukocytes and lysosomal enzymes n nEnzymes and ROS may be released into the extracellular environment n nInflammation is also capable of damaging normal tissues (the pathologic consequences of inflammation) Phagocytosis nRecognition and attachment of the particle to the ingesting leukocyte n nEngulfment , with subsequent formation of phagocytic vacuole n nKilling and degradation of the ingested material n 16-08a_phagocytosis_1 Phagocytosis n Cells involved in inflammation – components of cellular exudate nLeukocytes – neutrophils nEosinophils, basophils nLymphocytes nPlasma cells nMacrophages nHeparinocytes, mast cells nPlatelets nFibroblasts nErythrocytes PBBasophil basophil lymphocyte Histiocyte-100x-website-arrow Macrophages - histiocytes Mast-cell-and-basophil-100x-website-arrow Mast cell Plasma cell Plasma cell eo104le_eosinophil ly100le_lymphocyte th100le_platelet Mediator Source Principal action Cell-derived Histamine Mast cells, basophils, platelets VD, ↑permeability, ↑endotel. activation Serotonine Platelets VD, ↑permeability Prostaglandins Mast cells, leukocytes VD, pain, fever Leukotriens Mast cells, leukocytes ↑permeability,CHT,leu adhesion+activ. Platelet-activating factor Leukocytes, endothelial cells VD, ↑P, leu adhesion+activ., CHT,degranulation,... Nitric oxide Endothelium, macrophages vascular SM relax., microbes killing Cytokines (TNF, IL-1) Leukocytes ↑endotel. activation, systemic acute phase damage Reactive oxygen species Macrophages, lymphocytes,.. Microbes killing,tissue damage Chemokines Leukocytes, macrophages CHT, leu activation Plasma protein-derived Complement Plasma (produced in liver) Chemotaxis,opsonization,VD Kinins Plasma ↑permeability, VD, pain,… Proteases activated during coagulation Plasma Endothelial activation, leukocyte recruitment Major cell-derived mediators of inflammation – summary: nVasoactive amines: histamine, serotonine; VD, ↑permeability n nArachidonic acid metabolites: prostaglandines and leukotriens; vascular reaction, chemotaxis,… n nCytokines: IL-1, TNF, chemokines,…; multiple effects in leukocytes recruitment and migration n nReactive oxygen species: tissue damage, microbial killing n nNitric oxide: VD, microbial killing n nLysosomal enzymes: microbial killing, tissue damage n Plasma protein-derived mediators of inflammation nComplement proteins: n activation of complement→generation of multiple breakdown products→chemotaxis, opsonization, phagocytosis, cell killing n nCoagulation proteins: n activated factor XII triggers: clotting, kinin and complement cascades, fibrinolytic system n nKinins: n produces proteolytic cleavage of precursors; mediate vascular reaction, pain n Inflammation – microscopic appearance ðALTERATION: n tissue damage - regressive changes, necrosis n ðEXUDATION: n vascular leakage of protein-rich fluid and blood cells n Inflammation – microscopic appearance ðPROLIFERATION: n proliferation of fibroblasts and capillaries n formation of granulation and fibrous tissue û ðIMMUNE RESPONSE: n antigen presentation n T and B-lymphocytes reaction n production of antibodies by plasma cells n memory cells Classification of inflammation: nacute nchronic n n nnon-specific (non-granulomatous) ngranulomatous n n NONSPECIFIC inflammation nClassification: ðalterative: n alteration of tissue dominates n viral hepatitis, prion diseases [Creutzfeld-Jacob, BSE], diphteric myocarditis ðexudative: n most common, exudation prevails n superficial and deep, interstitial n serous and catarrhal, fibrinous, nonpurulent, purulent, gangrenous ðproliferative: n formation of fibrous tissue Alterative inflammation (liver necrosis) copy Exudative inflammation ûtopography of inflammatory changes: ðsuperficial (mucous membrane, serous membranes, skin) ðdeep (interstitium) û ûexudate components: ðserous ðfibrinous ðnonpurulent ðpurulent ðgangrenous Exudative inflammation ûserous: ðwatery exudate n few proteins (fibrinogen) n in mucous membranes – catarrhal (mucus) ðheals by inhibition of exudation ðexamples: n superficial: catarrhal appendicitis n deep (interstitial): urticaria (hives) Exudative inflammation ûfibrinous: ðhigh content of fibrinogen – fibrin in the exudate ðhealing is more complicated (fibroproductive inflammation) ðexamples: n superficial inflammation of serous membranes: nfibrinous pericarditis (upon uremia) = cor villosum, hirsutum n superficial infl. of mucous membranes (PSEUDOMEMBRANES): nplaque-like inflammations n deep: nrheumatic fever Fibrinous pericarditis – cor villosum (superficial fibrinous inflammation of serous membranes) copy Exudative fibrinous mucosal inflammation nClassification due to mucosal damage: • ûcroupous ðlittle alteration, plaque is loose on the surface n (croupous pneumonia) ð ûdiphteric ðdeeper mucosal necrosis, after the pseudomembrane is peeled off » n ulcus n (pseudomembranous colitis) ð ûescharotic ðextensive deep necrosis n (necrotising tracheitis in flu) Exudative inflammation nnon-purulent: n exudate made by chronic inflammatory cells n (lymphocytes, plasma cells = mononuclear/lymphoplasmocytic inflammatory infiltration) n nExamples: nInterstitial pneumonia n - infectious (viral, caused by small bacteria (Mycoplasma pneumoniae) or by fungi n (Pneumocystis carinii)) n - idiopathic (v.s. autoimmune) nInterstitial myocarditis nHashimoto`s lymphocytic thyreoiditis (autoimmune) Non-suppurative/non-purulent inflammation – lymphoplasmocytic – interstitial myocarditis myokarditis 40x myokarditis 200x Exudative inflammation ûpurulent: ðPRODUCTION OF PUS: n neutrophil-rich exudate ðGROSS: n superficial pus, pus accumulation (abscess) ðheals by inhibition of exudation and/or by proliferative inflammation ðexamples: n superficial inflammation of meninges: npurulent meningitis n superficial mucosal inflammation: ncatarrhal-purulent bronchopneumonia n deep (interstitial): nphlegmona (e.g. phlegmonous appendicitis) nabscess Suppurative (purulent) inflammation: purulent meningitis and absceding bronchopneumonia meningitis1 plíce povrch abscesy Exudative inflammation ngangrenous: n necrosis modified with putrid bacteria n examples: gangrenous cholecystitis Proliferative inflammation nformation of granulation tissue and fibrotisation in healing (reparation) of defects (wound, regressive changes, postinflammatory etc.) ntissue damage → granulation tissue → scar n noften pronounced in chronic inflammation n nprimary proliferative inflammation uncommon (fibromatosis) n nreactive fibro/myofibroblastic lesions nproliferation of myofibroblasts, occasionally forming tumour-like masses nnodular fasciitis, myositisossificans – may be posttraumatic, often idiopathic n Granulation tissue nFormation of granulation tissue = major repair instrument n n In: n healing of wounds, fractures, ulcers; organisation of necrosis, thrombus, and haematoma n n Gross: n soft red tissue, granular surface (capillary loops) n nMicro: n fibrin fibers n inflammatory reaction n fibroblasts, myofibroblasts n starting collagen fibers production n proliferating capillaries – angiogenesis n later intercellular matrix + tissue remodeling, retraction – scar formation n n n n Granulation tissue: (new vessels proliferation and fibrosis) HE40x 1 surface 2 proliferation of capillaries 3 tissue with inflammatory cells 2 1 1 1 2 2 3 3 Chronic inflammation nChronic inflammation developing from acute inflammation (e.g. chronic osteomyelitis,…) n nPrimary chronic inflammation -Resistance of infective agents to phagocytosis and intracellular killing (tbc, leprosy, brucellosis,…) -Foreign body reactions -Some autoimmune diseases -Specific diseases of unknown etiology (IBD,…) -Primary granulomatous diseases (sarcoidosis, reaction to beryllium,…) n Chronic inflammation nProlonged duration – prolonged host response to persistent stimulus n→ active inflammation+tissue injury+healing n nInfiltration with mononuclear cells (macrophages, plasma cells, lymphocytes) n nTissue destruction (by products of the inflammatory cells) n nRepair (new vessel proliferation and fibrosis) Macroscopic apperance of chronic inflammation nChronic ulcer nChronic abscess cavity nThickening of the wall of a hollow viscus nGranulomatous inflammation nFibrosis n Chronic peptic ulcer in stomach. he40x Microscopic features of chronic inflammation nExudation not prominent nProduction of new fibrous tissue from granulation tissue nContinuing destruction of the tissue+regeneration+repair nCellular reaction in chronic inflammation -macrophages, plasma cells, lymphocytes, eosinophils, mast cells - Chronic inflammatory cells and mediators (I) nMacrophages -derived from circulatin blood monocytes -mononuclear phagocyte system: liver: Kupffer cells; lymph nodes, spleen: sinus histiocytes; CNS: microglia; lungs: alveolar macrophages -Activated by bacterial endotoxins, by cytokines from immune activated T cells (IFN-γ),… -Activated macrophages secrete a variety of biologically active products (acid and neutral proteases, ROS, NO, AA metabolites, IL-1, TNF, GFs influencing proliferation of smooth muscles and fibroblasts) Chronic inflammatory cells and mediators (II) nLymphocytes (B and T) -Interaction with macrophages -TCR on macrophages, produce cytokines (IL-2) stimulating T-cells, which produce cytokines (IFN-γ) activating macrophages -Plasma cells derived from activated B-cells: production of antibodies against persistent antigens n nEosinophils (immune reactions mediated by IgE) -in parasitic infections -in allergies n nMast cells -In both chronic and acute inflammation -IgE coated mast cells release histamins, AA metabolites -Central players in allergic reactions, incl. anaphylactic shock n n Granulomatous/specific inflammation ndistinctive pattern of chronic inflammation nhistorical classification of inflammation: n„non-specific“ /non granulomatous inflammation n common general microscopic picture, i.e. purulent infl. n „specific“/granulomatous n micro typical for a specific cause n naggregated macrophages unable to destroy cause → transformation into epithelioid and multinuclear cells → granuloma ndelayed type hypersensitivity (T-cells, macrophages, sometimes eosinophils) nforeign body granuloma x immune granuloma n Granulomatous inflammation nAggregates of activated macrophages (epitheloid) n nNon-immune granulomas (response to foreign bodies, chemicals ) n nImmune granulomas -Necrotizing (tbc) -Non-necrotizing (sarcoidosis) n nPersistent T-cell response n nTuberculosis – a prototype of granulomatous disease n n n n Examples of diseases with granulomatous inflammation disease cause Tissue reaction Tuberculosis Mycobacterium tbc Caseating tubercle –granuloma Leprosy Mycobacterium leprae Noncaseating granuloma, acid-fast bacilli in macrophages Syphilis Treponema pallidum Gumma: enclosing wall of histiocytes, plasma cells infiltrate, central cells necrotic Cat-scratch disease G- bacillus Granuloma with central necrotic debris and neutrohils Sarcoidosis Unknown etiology Noncaseating granuloma with abundant activated macrophages Foreign body granulomas Response to foreign bodies (endogeneous (keratin, necrotic bone, cholesterol crystals, urate) and exogeneous (suture material, silica, talc, asbestos), chemicals (berrylium) Giant cell granulomas (foreign body granulomas) Crohn disease (IBD) Immune reaction against intestinal bacterial, self antigens Noncaseating granuloma in bowel wall +chronic inflammatory infiltrate Tuberculosis netiology nMycobacterium tuberculosis nZiehl-Neelsen staining, acid-resistant bacteria , culture or PCR detection n n tuberculous granuloma - basic morphology: n central caseous necrosis (basophilic nuclear fragments) n epithelioid macrophages n multinucleated Langhans‘ giant cells (fusion of macrophages) n rim of T-cells n Tuberculous granuloma 1caseous necrosis 2epiteloid cells 3Langhans´ giant cells 4lymphocytes 1 2 2 3 4 3 Granulomatous-purulent lymphadenitis – cat scratch disease. granulom nekrot Sarcoidosis of a lymph node granulomat la2 Granulomatous giant cell reaction around foreign bodies. granulom cizí těleso Systemic effects of inflammation nFever n (cytokines (TNF, IL-1) stimulate production of PGs in hypothalamus) nConstitutional symptoms n (malaise, anorexia, nausea, weight loss in chronic inflammation) nProduction of acute phase proteins n (CRP, fibrinogen, SAA – synthesis stimulated by cytokines (IL- 6)) nHaematological changes: leukocytosis, increased erythrocyte sedimentation rate, anaemia nIn some severe infections, septic shock (↓BP, DIC, metabolic abnormalities) nSecondary amyloidosis (in chronic inflammation) nhealing of tissue defects nRegeneration nRepair nregeneration and repair often in combination n ntissue adaptation to the changed conditions nHypertrophy: increase in cell size without cell division nHyperplasia: increase in cell number with mitosis nCombined hypertrophy and hyperplasia nMetaplasia: transformation of one mature differentiated cell type into another; affects epithelial and mesenchymal cells, oftes assoc. with increased risk of malignancy (e.g. squamous cell carcinoma assoc. With squamous metaplasia in bronchi) Progressive changes REGENERATION nreplacement by identical tissue – regrowth of original tissue (morphologically and functionally) n n n naccording to regenerative ability: nlabile cells nepithelial cells of skin, gut,…, bone marrow,…, npermanent regeneration from stem cells (rapid „turn-over time“) nstable nliver, kidney (proximal tubule epithelial cells), smooth muscle nregeneration on demand in tissue loss npermanent (postmitotic) nneurons, cardiac muscle cells nmostly no complete functional regeneration REPAIR nreplacement of lost tissue usually by granulation tissue → fibrotic scar (formation of connective tissue scar n n nmay affect the function of the organ nscar after myocardial infarction nlung fibrosis, cirhosis,… Components of tissue healing nFibronectin n(in early stages; formation of scaffold, the provision of tensile strength, the ability to „glue“ other substances and cells together, attracts fibroblasts and macrophages, binds to collagenes and proteoglycans ) n nProteoglycans and elastin n(stabilizes tissue undergoing repair) n nCollagen n(structural support and tensile strength, different type of collagen give stability to healing tissue) n Factors influencing regeneration and repair nPhysiological variables (e.g., age, grawth factors, vascular sufficiency) nGeneral health of the individual; immunocompetency; psychological/emotional/spiritual well-being nPresence of comorbidities (examples): -Diabtes mellitus -Decreased oxygen perfusion -Hematologic disorders -Cancer (local and systemic effect) -Incontinence -Alzheimer disease -Neurologic impairment -Immobility nTobacco, alcohol, coffeine, other substance use/abuse nLocal or systemic; presence of foreign bodies nType of tissue nMedical treatment (e.g., prednisone, chemotherapy, radiation therapy) Phases of wound healing nHemostasis and degeneration n nInflammation n nProliferation and migration phase n nRemodeling and maturation phase -Tissue contraction and contracture -Tissue regeneration -Tissue repair (formation of scar tissue) Phases of wound healing nBleeding, formation of a loose clot nMediators released by platelets (production of growth factors, recruitment of inflammatory cells) nProliferation and migration of fibroblasts, epithelial cells and vascular endothelial cells nProduction of fibronectin, proteoglycans, elastin, collagens by fibroblasts nReconstitution of extracellular matrix (=framework for the endothelial and parenchymal cells) nFormation of granulation tissue nRemodeling and maturation (decline of neovascularisation and fibroblasts proliferation; transformation of fibroblasts into myofibroblasts and contraction of the healing tissue) nFormation of scar tissue n n Stages of wound healing nhealing by first intention - per primam; union of accurately coapted edges of a wound, with an irreducible minimum of granulation tissue, results in a thin scar. n nhealing by second intention - per secundam; union by adhesion of granulating surfaces. n nhealing by third intention - per tertiam; union of a wound that is closed surgically several days after the injury. Keloid – hypertrophic scar tissue due to excess collagen formation Fracture healing and repair nSkeletal muscle -Transection of musles regenerate either by growth from undamaged stumps or by growth of new independent fibers (source of myoblasts for fiber regenerations - activated proliferating satellite cells) -Granulation tissue formation and connective tissue scar replacing the damaged muscle fibers – repair - nPeripheral nerve -Myelin degeneration and axonal fragmentation -Axonal sprouting and proliferation of Schwann cells in 24h -Microsurgical approximation may result in reinervation nTendon injury and healing -as a result of proliferation of tenoblasts from the cut ends -as a result of vascular ingrowth and proliferation of fibroblasts from the surrounding tissues - nLigament injury and healing -Healing by the same basic phasis (hemorrhage, inflammation, repair, remodeling) -Some with poor healing response n nCartilage injury and healing -Requires source of cells, provision matrix, removal of stress concentration, intact subchondral bone plate -Lack of articular cartilage vascularisation -Healing by fibrous scar or fails to heal at all n nSynovial membrane injury -hemorrhage, hypertrophy, hyperplasia of synovial lining cells, and chronic inflammation n nDisk degeneration -Degerative changes with age -Herniation of the disk - n Thank you for your attention …