Chronic Inflammation Flashcards
What is chronic inflammation?
- inflammation of prolonged duration
- active inflammation -> tissue destruction -> attempts at repair processed simultaneously
- may follow acute
- often begins insidiously as low grade, smoldering, asymptomatic response
Causes of chronic inflammation?
- persistent infection
- persistent toxins
- autoimmune disease
- can result in scarring
Histologic features of chronic inflammation?
- infiltration of mononuclear cells
- macrophages, lymphocytes, plasma cells, mast cells, eosinophils - tissue destruction
- hallmark of chronic - attempts at healing
- connective tissue replacement, angiogenesis, fibrosis
what happens within 48 hours after acute inflammation?
- within 48 hours, monocyte predominates
- monocyte migration similar to PMNs
- monocyte transforms in tissues to macrophages
- macrophage is central player in chronic inflammation b/c it produces a large variety of substances
Describe the maturation of mononucelar phagocytes?
see picture
what are the macrophages in the liver?
kupffer cells
What are the three mechanisms for macrophage accumulation and persistence in chronic inflammation?
- recruitment- chemotactic mediators (MCP1), differentiates
- Division- IL-6 production, macrophages in tissues start dividing
- IL-6 causes migration, immobilization
Products released by macrophages?
- enzymes
- neutral proteases
- elastase
- collagenase
- plasminogen activator
- acid hydrolases
- phosphatases
- lipases
- plasma proteins
- complement components
- coagulation factors
- reactive metabolites of oxygen
- eicosanoids
- cytokines, chemokines
- growth factors
- nitric oxide
what are the actions of chemokines?
- activate adhesion molecules
- act through G protein coupled transmembrane receptors and cause calcium influx (actin effect)
- induce haplotaxis (cell migration along surface gradients)
- bind to proteoglycans and ECM
- induce oxygen burst and release of PMN proteinases
what are the major features of chronic inflammatory response?
- injurious agent persists in tissue for weeks, months, years
- cell response to persistent injury generally consists of macrophages and lymphocytes
- granuloma formation occurs upon prolonged macrophage stimulation
- tissue necrosis within growth of fibrovascular granuulation tissue results in scar formation
- persistent neutrophilic exudation is occasionally present in chronic inflammation
what are the two stimuli for macrophage activation? what are the outcomes?
- activated T cell- complementary interaction, macrophage activates T cell
- non immune activation- endotoxin, fibronectin, chemical mediators
- outcomes: tissue injury or fibrosis
what is the complementary interaction of macrophage-lymphocyte?
activated lymphocytes can activate macrophages and vice versa through cytokines
common causes of reactive monocytosis?
infectious agents:
Tuberculosis
Subacute bacterial endocarditis
Rickettsial diseases
Syphilis
Brucellosis
Typhoid fever
Leishmaniasis
Following acute infections
Associated with malignant disease:
Preleukemia & Leukemias
Myeloproliferative syndrome
Hodgkin’s disease & Lymphomas
Multiple Myeloma
Non-hematologic malignant disease
Associated with other conditions:
Neutropenia and anemias
Systemic lupus Erythematosus
Rheumatoid arthritis
Sarcoidosis
Drug reaction
when would granuloma form?
delayed (type 4) hypersensitivity
-lymphocytes make a cup around macrophages, epithelioid
TB chest xray?
difference in bone density, ciruclar areas are where granulomas are seen