Endothelium, plaque rupture and vascular injury Flashcards
What is endothelium?
- Tissue consisiting of a single layer of cells that lines the blood and lymph vessels, heart, and some other cavities
- Arteries vs capillaries vs veins vs lymphatics
What are the tissues present in the Tunica Intima?
Tunica intima = endothelium + thin layer of connective tissue (CT)
What are the layers of tissue present in the Tunica Media?
- Tunica Media = vascular smooth muscle and connective tissue
What layers of tissue are present in Tunica Adventitia?
Adventitia = loose CT
In a very BROAD sense what is the difference between large arteries, smaller arteries, and arterioles?
- Large Arteries - more elastin
- Small Arteries - more collagen
- Arterioles - more smooth muscle
What is the effect of inflammatory activation on endothelial and smooth muscle cells?
- Inflammatory activation of these vascular cells corrupts their normal functions and favors proartherogenic mechanisms that drive plaque development
What was the first gas to be discovered as a signaling molecule in the body?
Nitric Oxide (NO)
What is Nitric Oxide’s role in the body?
-
cGMP-mediated vasodilation
- Expressed on luminal side of endothelium
- Made by NO Synthase (enzyme catalyst)
- Come from L-Arginine
What are the 3 main inflamatory molecules that promote an “inflammatory state” in the endothelium?
- Selectins
- Cell Adhesion Molecules (CAM)
- Cytokines
Describe the formation of an atheroscleoritc plaque begining from a monocyte
Hint - Monocyte is the first step
*see attached image for more detailed depiction
Monocytes -> Macrophages -> Foam Cells -> SM cell activation / migration ->
- Apoptosis
- Fibrosis
- Ongoing inflammation
What are the 3 steps of atheroscleoritc plaque progression?
- Fatty Streak formation
- Endothelial dysfunction
- Lipoprotein entry/modification
- Leukocyte recruitment
- Foam cell formation
- Plaque Progression
- SM cell migration & inflammatory state
- Plaque disruption/rupture (unstable plaque)
- Thrombus formation
What are the features of a stable plaque?
Stable Plaques
- Rich in fibrous tissue
- Calcified
- Less lipid content
- Less inflammation
- Less apoptosis
What are the features of vulenrable plaques?
Vulnerable Plaques
- Less fibrous tissue
- Less calcified
- More lipid content
- More inflammation
- More apoptosis
Why do we care about vulnerable vs stable plaques?
Vulenrable plaques rupture, thrombose and lead to clinical events
- e.g. - leads to MI
What molecules regulate thrombosis?
- Heparin sulfate/thrombin - surface of endothelium
- NO / platelet activation - secreted by endothelium
- Prostacyclin - secreted by endothelium