1. Inflammatory Mediator
Section 3
Inflammatory Mediator

2. 1. Definition:
It is the chemical substances which cause or participate in inflammation
(1) Mediators originate either from plasma or cells
(2) Most mediators perform their biologic activity by initially binding to specific receptors on target cells.
(3) A chemical mediator can stimulate the release of mediators by target cells themselves.

3. (4) Mediator can on one or few target cell types, or have widespread targets, or may even have differing effects, depending on cell and tissue types.
(5) Once activated and released from the cell, most of these mediators are short-lived
(6) Most mediators have potential harmful effects.

4. 2. Types of mediator (1) Cell produce serotonin
Arachidonic acid metabolic products: LTB4、LTC4、LTD4、LTE4
Cell products: O2-, H2O2, acid protease, neutral proteinase.
Cytokine: IL-1β, 2,3,4,6,7,10,12, IFN-γ, TNF-α, CSF.
Platelet activating factor( PAF)
nitric oxide(NO)

5. 2. Types of mediator (2) body fluid produce Kinin system
Complement system
Clotting system

6. 2. Types of mediator Summary of mediators of acute inflammation
Source
Action
Vascular Leakage
Chemotaxis
Other
Histamine and serotonin
Mast cells, platelets + _
Bradykinin
Plasma substrate
Pain
C3a
Plasma protein via liver
Opsonic fragment (C3b)
C5a
Macrophages
Leukocyte adhesion, activation

7. Potentiate other mediators
Source
Action
Vascular Leakage
Chemotaxis
Other
Prostaglandins
Mast cells from membrane phospholipids
Potentiate other mediators _
Vasodilation, pain, fever
Leukotriene B4
Leukocytes +
Leukocyte adhesion, activation
Leukotriene C4, D4, E4
Leukocytes, mast cells
Bronchoconstriction, vasoconstriction
Oxygen metabolites
Endothelial damage, tissue damage

8. Action Vascular Leakage Chemotaxis Other + _
Mediator
Source
Action
Vascular Leakage
Chemotaxis
Other
PAF
Leukocytes, mast cells +
Bronchoconstriction, leukocyte priming
IL-1 and TNF
Macrophages, other _
Acute phase reactio- ns, endothelial act- evasion
Chemokines
Leukocytes, others
Leukocyte activation
Nitric oxide
Macrophages, endothelium
Vasodilation, cytotoxicity

9. Main mediators function
Types of mediator
Vasodilation
Histamine, Bradykinin, Nitric oxide,
Prostaglandins PGE2, PGD2,PGF2, PGI2
Vascular Leakage
Histamine, Bradykinin, C3a, C5a, PAF, active oxygen metabolic products, Leukotrienes C4, D4, E4 Substance P
Chemotaxis
C5a, LTB4, bacterial products, IL-8, TNF.
Fever
IL-1, IL-6, TNF, PG.
Pain
PGE2, Bradykinin
Tissue damage
Neutrophil and macrophage lysosomal enzymes
Oxygen metabolites, Nitric oxide