Inflammation Flashcards
What is inflammation?
Reactions of living vascularised tissue to sub-lethal cellular injury. Evolutionary development to protect against infection and trauma. Can be local/systemic, tightly regulated and involves many cell types/mediators.
What is acute inflammation?
Short and early response to injury
- Hours/few days
- Involves release of chemical mediators
- Vascular and leukocyte response
What is chronic inflammation?
Inflammation of prolonged duration in which active inflammation, tissue destruction and attempts at repair occur simultaneously.
- Weeks/months/years
- Usually due to persistent injury causing agent
What are the main components of the inflammatory response and healing?
- Cells
- ECM
- Soluble factors
- Vessels
Which cells are involved in inflammation and healing?
Neutrophils, macrophages, lymphocytes, eosinophils, mast cells
Which components of the ECM are involved in inflammation and healing?
- collagen
- proteoglycans
- fibroblasts
What is the role of vessels in inflammation and healing?
- immediate supply of cells and soluble factors
Which soluble factors are involved in inflammation and healing?
- Antibodies
- Cytokines
- Complement system
- Coagulation system
What are the cardinal signs of inflammation?
- RUBOR: redness (slowed blood flow and vasodilation by histamine)
- CALOR: heat (vasodilation by histamine)
- DOLOR: pain
- TUMOUR: swelling (oedema due to increase in permeability by histamine)
- FUNCTIO LAESA: loss of function (due to swelling and pain)
What is histamine?
- Vasoactive amine
- Produced by mast cells
- Packaged into granules inside mast cells - when antigen binds to IgE on the surface of mast cells - causes cross-linking and degranulation
What are the two main effects of histamine?
Vasodilation
Increased Vascular Permeability
What does dysregulation of histamine result in?
Allergy (Type 1 Hypersensitivity)
What are some other important mediators in inflammation and what do they do?
Prostaglandins: PGE2 causes vasodilation, pain and fever
PGI2 causes vasodilation
Chemokines: activate neutrophil chemotaxis
Complement: variety of proteins and actions including stimulating mast cell degranulation, neutrophil chemotaxis and osponisation
Cytokines (Interleukins and TNF): actions include pro and anti inflammatory signalling, inducing fever, weight loss and malaise
How are histamines, prostaglandins and IL-1 and TNF targeted?
prostaglandins- aspirin
histamine - anti-histamine
IL-1, TNF - anti TNF antibodies
What is exudate?
A fluid with a high content of protein and cellular debris which has escaped from blood vessels and has been deposited in tissues or on tissue surfaces, usually as a result of inflammation. FLUID LEAKS
What is transudate?
Caused by disturbances in hydrostatic and colloid osmotic pressure, not caused by inflammation.
FLUID FORCED OUT
What is the composition of transudate?
- low protein
- few cells
- low specific gravity: ratio of density of substance to reference substance
What is the function of exudate?
It contains cells, fluid, proteins and antibodies etc.
Fluid - dilutes pathogen and allows soluble mediators to spread
Fibrin - walls off pathogen to stop it spreading. Gives inflammatory cells substrate to hold on to/migrate through
What are the types of exudate?
Serous = fluid filled
Lowest protein content of all the exudates. E.g. blister
Fibrinous = High fibrin content
More due to traumatic injury
E.g. Viral Pericarditis
Purulent = pus filled
Combination of fibrin, inflammatory cells, debris and fluid
E.g peritonitis following bowel perforation
What are the cellular events that occur during acute inflammation and what is the main cell involved?
NEUTROPHILS
1) Enters into tissues
2) Migrate via chemotaxis
3) They become activated
4) They carry out phagocytosis
5) They release mediators and interact with other cells
What is the main role of neutrophils?
- Kill bacteria and recruit more cells
- Phagocytosis
- Degranulation
FIRST CELLS TO SITE
How do phagocytes kill the engulfed material?
By free radicals, lysozyme, lactoferrin (binds iron and stops bacteria reproducing), major basic protein (produced by eosinophils - cytotoxic to helminth parasites)
How is the inflammation reaction controlled?
- Mediators and neutrophils have short half life
- Stimulus (e.g. bacteria) removed
- Mast cells and lymphocytes release anti-inflammatory products (lipoxins)
- Macrophages release anti-inflammatory products
Can tissue damage occur during acute inflammation?
Yes, the body responding tot the agent causing inflammation can lead to necrosis.