Pathogenesis and Chronic Inflammation

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Questions and Answers

What is a key feature of granulation tissue?

It is only involved in granuloma formation

Fibroblasts play an essential role in its formation (correct)

New vessel formation does not occur

Macrophages are not involved in the process

What is the main function of macrophages in granulation tissue?

To kill foreign material through lysosomal content

To release cytokines

To stimulate fibroblast accumulation

To clear debris and fibrin (correct)

What is the role of Th1 response in tuberculosis?

To activate macrophages to become bactericidal

To stimulate formation of granulomas

To release IFN-gamma

All of the above (correct)

What type of cells have a good capacity to proliferate?

Labile cells Signup and view all the answers

What is the process of healing by primary intention?

Healing of a clean, uninfected surgical incision Signup and view all the answers

What is the process of repair by fibrosis?

Laying down of fibrous tissue Signup and view all the answers

What is the role of fibroblasts in granuloma formation?

They are only sometimes involved in the final stages Signup and view all the answers

What is the outcome of delayed hypersensitivity to MT antigen?

All of the above Signup and view all the answers

What is the primary difference between acute and chronic inflammation in terms of time span?

Chronic inflammation lasts for a longer duration Signup and view all the answers

What type of cells are involved in chronic inflammation?

Macrophages, plasma cells, and lymphocytes Signup and view all the answers

What is the purpose of granulomas in chronic inflammation?

To destroy foreign material Signup and view all the answers

What is the mechanism of excessive macrophage accumulation in chronic inflammation?

Continous recruitment from circulation and local proliferation Signup and view all the answers

What is the difference between necrotising and non-necrotising granuloma?

Necrotising granuloma has central area of necrosis, while non-necrotising granuloma has no necrosis Signup and view all the answers

What is the purpose of granulation tissue in chronic inflammation?

To repair pre-existing defects Signup and view all the answers

What is the role of CRP in chronic inflammation?

To increase if there's inflammation Signup and view all the answers

What is the characteristic of ESR in chronic inflammation?

Quicker sedimentation rate means inflammation is more likely Signup and view all the answers

Study Notes

Pathogenesis of Chronic Inflammation

Progression from acute inflammation that is not totally resolved
Involves macrophages, lymphocytes, and plasma cells

Mechanism of Chronic Inflammation

Excessive macrophage accumulation due to continuous recruitment, local proliferation, and immobilization of peripheral macrophages

Morphology of Chronic Inflammation

Granuloma: aggregation of macrophages that form in response to chronic inflammation
- Macrophages secrete IL-1, interferon alpha, and TNF
- Macrophage elongation leads to formation of epithelioid histiocytes
- Epithelioid histiocytes and macrophage accumulation leads to giant cell formation
- Types of granulomas: necrotising granuloma (central area of necrosis, occurs in TB) and non-necrotising granuloma (no necrosis, occurs in Sarcoidosis)
Granulation tissue: new connective tissue and microscopic blood vessels that form during healing

Difference between Acute and Chronic Inflammation

Longer time span
Tissue destruction, inflammation, and healing all happen simultaneously
Cells involved: polymorphonuclear cells in acute inflammation, macrophages, plasma cells, and lymphocytes in chronic inflammation

Diagnostic Laboratory Tests

ESR (Erythrocyte Sedimentation Rate): measures rate at which RBC separate from plasma and fall to the bottom of the tube
- Quicker sedimentation rate means inflammation more likely
CRP (C-Reactive Protein): CRP is produced by the liver and increases if there's inflammation
PV (Plasma viscosity): more viscosity means inflammation more likely

Granulomatous Inflammation

Purpose: granulation tissue repairs pre-existing defects, granulomas destroy foreign material but may destroy tissue as well
Components: new vessel formation occurs in granulation tissue, no new vessels occur in granulomas
Fibroblasts: play an essential role in granulation tissue formation, sometimes involved in the final stages of granuloma formation
Activity of macrophages: in granulation tissue, macrophages clear debris and fibrin, direct new vessel formation and fibroblast accumulation through secretion of growth factors; in granulomas, macrophages try to kill foreign material through release of lysosomal content and cytokine secretion

Chronic Inflammation in Relation to Tuberculosis

Mycobacterium TB (mt hominis or mt bovis)
Pathogenesis:
- 0-3 weeks: MT enter macrophages via endocytosis, fever and malaise, nodule at site of infection or asymptomatic, delayed hypersensitivity to MT antigen (TM skin test)
- 4-6 weeks: Th1 response activates macrophages to become bactericidal, Th1 release IFN-gamma, stimulates macrophages to fuse with lysosome, Th1 stimulates formation of granulomas

Healing and Repair

Regeneration: growth of cells and tissues to replace lost structures
Repair by fibrosis/scarring: laying down of fibrous tissue
Examples:
- Skin: labile cells with good capacity to proliferate, will regenerate and repair quickly
- Liver: stable cells with slow proliferative rate unless necessary, permanent cells with no effective regeneration

Process of Healing by Primary and Secondary Intention

Primary Intention: healing of a clean, uninfected surgical incision
- Wound edges joined by fibrin
- Regrowth of basal layer of epidermis
- Lysis of fibrin and re-epithelialisation
- Restoration of skin
Secondary Intention: more extensive loss of cells and tissue
- Large defect filled via blood clot
- Granulation tissue grows from dermis into fibrin
- Granulation tissue fibroblasts lay down collagen
- Maturation of collagen restores skin integrity and regrowth of epidermis

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Description

This quiz covers the progression of acute inflammation to chronic inflammation, the role of macrophages, lymphocytes, and plasma cells, and the formation of granulomas.