Chronic Inflammation Flashcards
What is chronic inflammation?
Persistent inflammation that can occur over months and years - possibly forever
What are the 3 types of chronic inflammation?
1) Non-specific chronic inflammation;
- failure to resolve acute inflammation
2) Specific (primary) chronic inflammation;
- starts from beginning
- persistent exposure to agent
3) Chronic (secondary specific) granulomatous inflammation;
- Granulation tissue is new connective tissue & blood vessels that form on surfaces of a wound during healing process
What is non-specific chronic inflammation?
- (non-specific) Chronic inflammation arises from acute inflammation when immune system not sufficient to eradicate stimulus
- Characterised by dynamic balance between tissue destruction and repair
What is specific (primary) chronic inflammation?
- Can be granulomatous or non-granulomatous
- Characterised by excessively activated macrophages
- Can be induced by immunological and non-immunological agents
What is chronic (secondary specific) granulomatous inflammation?
- Specific chronic inflammation but predominant cell types are;
MODIFIED ACTIVATED MACROPHAGES:
-> Epithelioid macrophages (resembling epithelial cells), multiple = giant cells
- Can be immunological or non-immunological
What is an example of non-specific chronic inflammation?
Periodontitis
acute inflammation is gingivitis, if left untreated, progresses and amplifies into chronic
What is an example of specific (primary) chronic inflammation?
Autoimmune diseases (Rheumatoid arthritis)
- Due to failure of (Central & Peripheral) tolerance - positive and negative selection
- Body destroys own tissues/cells
What are the function of macrophages in chronic inflammation?
- circulate in blood as monocytes, differentiate into macrophages at tissue
- phagocytose & present antigens
- Can be M1 or M2 macrophages
- Produce essential proteins & enzymes
M1 = Pro-inflammatory (tissue injury) M2 = Anti-inflammatory (tissue repair)
How are granulomas formed?
1) macrophage present antigens to lymphocytes
2) Response from T lymphocytes
3) induces formation of epithelioid macrophages
4) multiple epithelioid macrophages combine to form giant cell
5) Engulfs foreign material
What is an example of chronic granulomatous inflammation?
Orofacial granulomatosis: granulomas in soft tissues of oral cavity & swelling
How does SOFT TISSUE destruction occur?
1) Immune system responds by recruiting & activating immune cells
2) RANKL produced (resulting in cell apoptosis)
3) Osteoclasts activated and osteoblasts have reduced function
4) MMPs (matrix metalloproteinases) activated -degradation of ECM proteins
How does HARD TISSUE (alveolar bone) remodelling occur and whats included in it?
- A balance of osteoblastogenesis and osteoclastogensis,
- RANKL/OPG ratio important, if ratio increases, balances towards bone loss/resorption
Osteoblasts secrete osteoprotegerin (OPG) which inhibits RANKL function - controlling bone resorption
Osteoclasts secrete RANKL - Apoptotic
