Atherosclerosis Flashcards
What is the definition of atherosclerosis?
chronic inflammatory disease of the tunica intima of medium and large arteries causing narrowing due to buildup of lipid followed by fibrosis
What is an atheroma?
earlier stage of atherosclerosis with buildup of lipid and lipid-laden macrophages in the tunica intima
What is vulnerable plaque?
atherosclerotic plaque with a large, loose atheromatous core and a thin fibrous cap–prone to rupture and occlusive superimposed thrombosis
What is the most common cause of death in the US?
atherosclerotic cardiovascular disease
Where does atherosclerosis occur?
medium (muscular arteries)–coronary and cerebral
large elastic arteries (aorta)
*favors branchpoints!
What are the 5 steps in the pathogenesis of atherosclerosis?
1) Malfunction of injured endothelial cells
2) Accumulation of lipid in tunica intima
3) Leukocyte recruitment into tunica intima
4) Foam cell formation
5) ECM deposition
What are the two most important causes of endothelial dysfunction?
1) Hemodynamic disturbances (places with turbulent flow)
2) Hypercholesterolemia (increase local oxygen free radical production–> decrease NO and dampens vasodilation)
What are the major effects of endothelial injury?
Decreased vasodilation (ex. NO and prostaglandins), increased release of inflammatory cytokines (ex. IL-1 and TNF-alpha) and decreased release of antithrombotic substances
When gets deposited into the tunica intima after endothelial injury?
LDL gets trapped by binding to ECM, is oxidized, glycated, and processed by macrophages and endothelial cells
What 2 things does oxidized LDL promote?
1) leukocyte recruitment
2) foam cell formation
What enzyme is produced by inflammatory cells, travels with circulating low-density lipoprotein (LDL), and hydrolyzes oxidized phospholipids in LDL?
Lipoprotein-associated phospholipase A2 (Lp-PLA2)
Lp-PLA2 increases the expression of what on the surface of endothelial cells?
MCP-1 (monocyte chemoattractant protein-1), ICAM-1 and VCAM-1
What other 2 effects does Lp-PLA2 have on endothelial cells? On macrophages?
Endothelial cells: vasodilate less in response to nitric oxide and undergo apoptosis.
Macrophages: upregulate MCP-1, secrete IL-1beta and apoptose.
What does the expression of VCAM-1 promote?
leukocyte adhesion
Recruitment of leukocytes to the tunica intima is dependent on what chemicals?
MCP-1, Interferon-inducible protein 10, and IL-8
What other than leukocytes is recruited to the tunica intima?
smooth muscle cells
What mediates the recruitment of SM cells to the tunica media?
PDGF, TNF-alpha, TGF-beta, and IL-1
What is a foam cell?
macrophages overstuffed with oxidized LDL
How do foam cells form?
monocytes are transformed to macrophages and phagocytose oxidized LDL through “scavenger receptors” that lack feedback mechanisms (so cell gets overstuffed!)
What chemicals are responsible for stimulating SM production of the ECM?
IL-1, TNF-alpha, TGF-beta, and FGF
What are the 5 Major Modifiable Risk factors for Athlersclerosis?
SHODDY
Smoking, Hypertension, Obesity, Diabetes, Dyslipidemia
What is the earliest (and reversible) form of lipid deposits int he tunica intima?
fatty streaks
What is a .3-1.5 cm raised yellow-white fibrofatty lesion composed of a soft lipid core (atheroma) covered by a fibrous cap?
atheromatous plaque
What is the structure composed of collagen, proliferating SM cells, macrophages, and lymphocytes?
fibrous cap
When do you see neovascularization in atherosclerosis?
it is a later feature
Describe neovascularization.
in-growth of capillaries from the vasa vasorum in the outer layer (adventitia) through the media and into the intima due to increased demand for oxygen and nutrients as the atherosclerosis presents the intima from getting proper nutrients from the lumen