WEEK 2/3 CVD ATHEROSCLEROSIS, CORONARY HEART DISEASE Flashcards
What is the single most important factor in cardiovascular disease?
Raised blood pressure.
Can high levels of cholesterol drive coronary heart disease (CHD)?
- Yes
What is familial hypercholesterolaemia and what is it caused from?
- This is when LDL cholesterol
from the plasma is engulfed by macrophages on the skin to form Xanthomas - This also happened in the coronary arteries of patient–> plaque on artery wall –> MI (heart attack)
- Homozygous FH inheritance
- Had their first myocardial infarction at 8yo
What is the largest lipoprotein and the smallest?
- Chylomicrons largest
- HDL –> smallest
What are the 4 different types of lipoproteins?
- Chylomicrons
- VLDL
- LDL
- HDL
Which type of Lipoprotein is the protective one?
- HDL
What does VLDL stand for?
- Very low density lipoproteins. (Triglyceride) that cannot pass through the blood vessel wall
- It contains Apo B 100 which is a ligand for LDL reuptake
What is the basic role of the Apo B 100 that is found in VLDL and LDL?
- It is a ligand for LDL reuptake to be recycled and reused
What does LDL stand for?
- Low density lipoproteins (cholesterol)
What is another name for VLDL?
- Triglyceride
What is another name for LDL or HDL (i.e. which class do they belong to?
- Cholesterol
What does LDL stand for?
- Low density lipoprotein
- It can easily penetrate the vascular endothelium
- Contains Apo-B -100
What is lipoprotein A formed from?
- LDL and contains Apo-B-100
- It is similar to and competes with plasminogen (degrading fibrin clots-blood clots)
Can LDL penetrate the vascular endothelium?
- Yes it can due to its size (small)
- this is NOT good
Is Liporprotein A, which is formed from LDL, a good or bad type of cholesterol?
- It is a bad type
What does HDL stand for?
- High density lipoproteins
- The species contain apo-A-I which is PROTECTIVE
Which two ways can Lipoprotein transport in the blood occur?
- Exogenous pathway
- Endogenous pathway
What occurs in the exogenous pathways of lipoprotein transport in the blood?
- There is cholesterol/triglycerides derived from the GIT
- Pass into the intestinal lymph
- transported as chylomicrons into the plasma
- then hydrolysed (broken down into FAs)
- goes into the muscle/adipose tissue
What occurs in the endogenous pathways of lipoprotein transport in the blood?
- You have cholesterol/triglycerides that are synthesized in the LIVER
- They are transported as VLDL and go straight to the muscle/adipose tissue
- Then lipoprotein particles become LDL and provides cholesterol
What type of receptor is the LDL receptor?
- A clearance receptor in liver cells
What sythesizes the LDL receptors?
- Liver and Vascular Smooth Muscle Cells (VSMC)
What is the term for HDL (incorperated into apoA-1) removing excess cholesterol from cells?
- Reverse cholesterol transport
There is a strong correlation between plasma [LDL] and _________.
There is a strong correlation between plasa [LDL] and atherosclerosis/CHD (cholesterol rich plaque)
There is a strong correlation between Lp(a) (found in plaques) and _____.
- There is a strong correlation between Lp(a) and CHD (cholesterol rich plaque).
- Reduced plasminogen favours increased thrombosis
With reduced plasminogen in the body because Lp(a) as outcompeted it, what does this promote?
- This promotes increased thromosis which is BAD
There is a correlation between [HDL] and ____.
- Lower CHD (cholesterol rich plaque)
In atherosclerosis is there early evidence of enothelial dysfunction?
- YES
Ideally, what is the ideal total cholesterol level in mmol/L?
- <5.6mmol/L
What is the ideal value for how much LDL cholesterol one should have in their blood?
- <2.5mmol/L
Does age become an issue with increasing cholesterol levels?
- YES
is atherosclerosis a short or long course of progression?
- Very long progression
- Decades long
What is a big contributor to atherosclerosis progression in terms of immune cells?
- Immune cells such as leukocytes ‘sticking’ to the endothelial surface–> monocytes maturing into macrophages that engulf the lipids
- This is vascular inflammation
What helps in maintaining vasodilator tone and thus an anti-thrombogenic surface?
- NO that is released
- This relaxed the smooth arterial muscle
- The endothelial cells were key to releasing NO that would then act on smooth muscle cells to cause vasodilation
- This means that if there are other immune cells sticking to it, so that the tissue is not available, then it cannot release NO and serious issues will occur.
What are two events occurring with excess oxidised LDL in the coronary artery?
- Oxidised LDL induces adhesion molecule expression (VCAM, ICAM1) on endothelium
- Oxidised LDL is phagocytosed by macrophages (these then form foam cells)
What are macrophages that ingest LDL called?
- Foam cells
At what age can foam cell start to appear?
Can occur in the 20s.
Where is vascular cholesterol uptake by LDL receptors important?
- Important in the liver but not in the blood vessel of the heart
- If in the blood vessel of the heart we have atherosclerosis
Once monocytes are recruited into the arterial wall, what occurs?
- They enter via adhesion molecules
- They differentiate into macrophages
- The macrophages then release inflammatory factors (cytokines etc) so then local tissue damage occurs
What types of antigens so DCs and macrophages present in plaque inflammation?
- Oxidised LDL
- Heat shock proteins
- Microbes
What allows for T cells (particularly Th1 cells) to infiltrate the site of the coronary artery in terms of plaque formation?
- Antigens such as Oxidized LDL are presented via APCs (DC or macrophage) to the T cell and causes it to differentiate into a Th1 cell and produce cytokines: IFN-y, IL-1B, IL-6, TNF-a (all the highly inflammatory cytokines)
- This then AMPLIFIES VASCULAR INFLAMMATION
Are Tregs still active in vascular inflammation?
- YES, they will still be producing anti inflammatory cytokines like IL-10 and TGF-b however the majority is inflammatory so this is outweighed by the inflammatory cytokines
What is CRP (C-reactive protein)?
- Acute phase protein synthesised in the liver that can be used as a biomarker for generalised inflammation
- This is predictive of CVD and informs on statin therapy
What is the mode of action for CRP?
- It binds to the surface of dying cells and promotes phagocytosis
What is CRP stimulated by?
- IL-6 from inflammatory cells
What can occur as a mechanism to try and stabilize the lipid core in the formation of atherosclerosis?
- A fibrious cap via collagen depositing to seal it off.
What happens if the fibrous cap ruptures?
- There can be a thrombus formation
Which cells are responsible for inhibiting cap fibrous cap formation?
- The Th1 cell via the release of IFN-y and decreaes collagen synthesis by smooth muscle cells
- The macrophage released MMP which degrades the collagen fibrils
Is the inflammasome involved in atherosclerois progression and inflamation?
- YES - very complicated process
Which cells produce collagen?
- Smooth muscle cells
Are there some drugs looking at inhibiting inflammatory factors to treat atherosclerosis?
- YES
e. g. IL-1b inhibition in Canakinumab BUT not approved by FDA for RISK REDUCTION (very expensive) - Treatment options not clear yet
Does plaque rupture generally come before or after thrombosis or a thrombus forming?
- It comes BEFORE the thrombus forms
- Plaque contents burst through the ruptured cap into the lumen in mins-hrs
Can thrombus/infarction occur throughout the whole body?
- YES
- But the outcomes are dependent on the location of the tissue injury
What are the symptoms associated with DVT (this has nothing to do with atherosclerosis!)?
- Sharp pain when foot is flexed
- tenderness and swelling in the leg
- Fever and rapid heart beat
- Sudden unexplained cough and joint pain
- Leg may become red and warm to touch
What are examples of acute presentation in terms of coronary heart disease (e.g. Acute coronary syndrome)?
- Angina–> radiating chest pain
- Acute myocardial infarction (AMI- heart attack)
- Others
What are examples of chronic coronary heart diseases?
- Stable angina
- Heart failure
What are two immediate treatments for life threatening events?
- Revascularization
2. Drugs
What is involved in revascularization for the treatment of life threatening events?
- A Percutaneous coronary intervention (PCI)/angioplasty usually with stents.
What is one type of drug that has a narrow therapeutic window, that we can use for the immediate treatment of life threatening events?
- Tissue palsminogen activator (recombinant tPA- rtPA)
What are two chronic drug treatments for atherosclerosis used for Prevention?
- Reducing the lipid/plaque/inflammation burden.(e.g. Lipid-lowering drugs–] statins and newbies PCSK9)
- Many other drugs help with CHD Burden (by decreasing the workload)
What are the three different types of hyperlipidaemia (dyslipidemia)?
- Cholesterol (hypercholesrerolaemia)
- Trigylcerides (hypertriglyceridaemia)
- Both (mixed)
What are the causes of CVD related hyperlipidaemia?
- Genetic e.g. FH (Familial hypercholersterolemia)–> defect in the LDL receptor
- Dietary excess
What types of diseases can hyperlipidaemia be secondary to?
- Diabetes mellitus
- Alcoholism, Obstructive liver disease, drugs
What type of feedback inhibition occurs with the LDL receptor in the synthesis of cholesterol?
- When the intracellular cholesterol content increases, there is NEGATIVE regulation that occurs
- Decrease in the productionof HMG CoA Reductase which decreases its synthesis in the hepatic cells
- Decrease in the LDL receptors
What are some things that you must consider in the treatment of hyperlipidaemia?
- CV status and risk factors
- If it is secondary to other diseases such as diabetes or hypertension, in which case you would treat those first
- You must consider lifestyle modification BEFORE any drug treatment.
What are two drugs used to treat hypercholesterolemia?
- Statins
- PCSK9 inhibitors
What is the main mechanism of action for statins in the liver?
- They inhibit the intracellular formation of cholesterol in the liver
- ‘HMG-CoA reductase inhibitors’ –> competitive enzyme inhibitor
e. g. Simvastatin (Zocor), Pravastatin (Pravachol), Atovastatin (Liptor) - Re