Pathology- Inflammation, wound healing Flashcards
Arachidonic acid
: mediator of acute inflammation; released from phospholipid membrane by phospholipid A2
- acted on by either cyclooxygenase = prostaglandins, or
- 5-lipooxygenase = leukotrienes
Significance of NF-KB
NF-KB is a nuclear transcription factor that is activated upon TLR activation by PAMPs
-TLRs are present on APCs and lymphocytes
Which prostaglandins mediate vasodilation and increased vascular permeability?
-vasodilation = arteriole; increased vascular permeability = post-capillary venule
: “DIE” PGD2 PGI2 PGE2
What are the functions of PGE2?
:vasodilation, vascular permeability, FEVER & PAIN
What are the important leukotrienes? What are the effects?
LTC4, LTD4, LTE4- THINK SM CONTRACTION
: vasconstriction, bronchospasm, increased vascular permeability
What are the main mediators of attracting PMNs?
- LTB4
- IL-8
- C5a
- bacterial products
How are mast cells activated?
- Cross-linking IgE
- complement (C3a, C4a, C5a)
- tissue trauma
Function of histamine
Vasodilation and increased vascular permeability
Note: delayed response is production of leukotrienes (recall hypersensitivity I) –> this is how the response is maintained
Hageman factor (Factor XII)
:inactive pro-inflammatory protein produced in liver; activated when exposed to subendothelial collagen
- activates coagulation cascade
- activates complement
- activates kinin system: kinin cleaves kininogen to bradykinin = vasodilation and increased vascular permeability + pain
Rubor & Calor
: d/t vasodilation occurs via SM relaxation of arteriole
- Key mediators: histamine, prostaglandins, leukotrienes
Tumor
:swelling; d/t leakage of fluid from postcapillary venules into interstitial space (exudate)
-Key mediator: histamine which causes endothelial cell contraction & tissue damage resulting in endothelial cell disruption
Dolor
:pain
-Key mediators: bradykinin and PGE2 –> sensitize sensory nerve endings
Fever
pyrogens (LPS from bacteria) cause macrophages to release IL-1, IL-6 and TNF
-IL-1 and TNF increase cyclooxygenase activity (PGE2) in perivascular cells of the hypothalamus which raises the temperature set point
Margination
- vasodilation at the arteriole slows blood flow at the POST-CAPILLARY VENULE
- cells marginate to the periphery of the vessel
P-selectin
:important in rolling, expressed on endothelial cells; released from weibel palade body of endothelial cells, mediated by histamine
-binds sailyl-Lewis X on leukocytes
E-selectin
:important in rolling, expressed on endothelial cells; induced by TNF and IL-1
-binds sailyl-Lewis X on leukocytes
What are the cellular adhesion molecules? What induces their expression?
- ICAM-1 (CD54) & VCAM (CD106)
- expressed on the endothelium, induced by TNF and IL-1
What are integrins? Function?
:bind to cellular adhesion molecules on the endothelial cell surface to promote tight adhesion
- CD11/18 integrins, (LFA-1, Mac-1), VLA-4 integrin
- Integrins are upregulated on leukocytes by C5a and LTB4
What are the steps of leukocyte extravasation?
- Margination and rolling
- Tight binding
- Diapedesis (transmigration)
- Migration and chemotaxis
What is the respiratory burst?
:generation of HOCl within the phagolysosome of the phagocytes
-O2 coverted to superoxide by NADPH oxidase
-Super oxide converted to hydrogen peroxide (H2O2) by superoxide dismutase
H2O2 converted to HOCL (bleach) my myeloperoxidase
Myeloperoxidase deficiency
:defective conversion of H2O2 to HOCl
- patients usually asymptomatic; presentation may be recurrent candida infections
- NORMAL nitroblue tetrazolium test b/c respiratory burst intact