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Year 1: Cardiovascular System > 17. Atherosclerosis > Flashcards

17. Atherosclerosis Flashcards

1
Q

What cells remove arterial tissue?

A

Macrophages

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2
Q

What cells make arterial tissue?

A

Smooth muscle cells

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3
Q

List the potentially modifiable risk factors

A 
o Smoking 
o Lipids 
o Blood Pressure
o Diabetes
o Obesity
o Lack of Exercise
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4
Q

List the not modifiable modifiable risk factors

A

o Age
o Sex
o Genetic Background

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5
Q

What is the risk associated when you have 2 or 3 different risk factors?

A

The risk associated is multiplicated

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6
Q

Describe the distribution of atherosclerosis

A

It is not evenly distributed and tends to arise at specific places. E.g The bifurcation of the common carotid artery

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7
Q

Where do atherosclerotic lesions tend to appear?

A

On the outside of a bend. When the blood goes around a corner too quickly you get turbulent flow

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8
Q

Where do LDLs deposit?

A

In the subintimal space and binds to matrix proteoglycans

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9
Q

When LDLs accumulate what does it also bring?

A

Macrophages

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10
Q

What do the macrophages do in the subinitmal layer?

A

They eat up the endothelial fat and become foam cells.

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11
Q

What happens to the foam cells produced?

A

They leave the subintimal layer

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12
Q

What does the lesion accumulate as fat deposition continues?

A

Pools of extracellular lipid, eventually the macrophages can no longer cope.

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13
Q

What happens when the fat builds up further?

A

A core of extracellular lipid forms - The pool of fats coalesce and forms a large mass of fat

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14
Q

How does a fibrous thickening form in the atherosclerosis?

A

Inflammation irritates the interior of the plaque

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15
Q

What do macrophages produce in the subintimal space?

A

Growth factors

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16
Q

What is the effect of growth factors?

A

They stimulate smooth muscle cells to grow and divide to make more collagen

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17
Q

What happens when the plaque ruptures?

A

The lipid core communicates with the lumen stimulating clot formation

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18
Q

What is the layer effect in atherosclrosis?

A

This comes from repeat episodes of plaque destabilisation

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19
Q

What are the main cell types involved in atherosclerosis?

A 
Vascular endothelial cells
Platelets
Monocyte-macrophages
Vascular smooth muscle cells
T Lymphocytes
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20
Q

What is the function of vascular endothelial cells in relation to atherosclerosis?

A
  • Barrier function

- Leukocyte recruitment

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21
Q

What is the function of platelets in relation to atherosclerosis?

A
  • Thrombus generation

- Cytokine and growth factor release

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22
Q

What is the function of monocyte-macrophages in relation to atherosclerosis?

A
  • Foam cell formation
  • Cytokine and growth factor release
  • Major source of free radicals
  • Metalloproteinases
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23
Q

What is the function of vascular smooth muscle cells in relation to atherosclerosis?

A
  • Migration and proliferation
  • Collagen synthesis
  • Remodelling and fibrous cap formation
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24
Q

What is the function of T lymphocytes in relation to atherosclerosis

A
  • Macrophage activation

They are activated by macrophages

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25
Q

What are the systems responsible for haemostasis

A

Clotting cascade

Platelet aggregation

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26
Q

What are foam cells?

A

Macrophages that have consumed fat or phagocytosed lipoproteins

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27
Q

What are matrix metalloproteinases?

A

They degrade major extracellular proteins such as collagen

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28
Q

What can abnormal vascular smooth muscle cells with an atherosclerotic plaque secrete?

A

Collagen

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29
Q

What is the function of collagen in atherosclerosis?

A

It contributes to the stabilisation of the plaque and fibrous cap

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30
Q

What are the main inflammatory cells in atherosclerosis?

A

Macrophages

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31
Q

What are the two main classes of macrophage?

A

Resident

Inflammatory

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32
Q

What is the function of inflammatory macrophages?

A

Adapted to kill microorganisms

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33
Q

What is the function of resident macrophages?

A

Mainly homeostatic:
o Suppress inflammatory activity
o Alveolar resident macrophages (surfactant lipid homeostasis)
o Osteoclasts (calcium and phosphate homeostasis)
o Spleen (iron homeostasis)

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34
Q

What are LDLs?

A

Low density lipoproteins

BAD cholesterol

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35
Q

Where are LDLs synthesised?

A

Liver

36
Q

What is the function of LDLs?

A

Carries cholesterol from the liver to the rest of the body (including the arteries)

37
Q

What are HDLs?

A

High density lipoproteins

38
Q

Where is the function of HDLs?

A

Carries cholesterol from the peripheral tissues including the arteries back to the liver

39
Q

How are oxidised/modified LDLs produced?

A

Free radical attack on LDLs

40
Q

What is function of oxidised/modified LDLs?

A

They are highly inflammatory and toxic forms of LDL found in vessel walls

41
Q

Describe the structure of an LDL

A

Consists of a monolayer with apoproteins on the surface

42
Q

What is the function of apoproteins?

A

They tell the LDL where to go

43
Q

Where are LDLs susceptible to modification?

A

In the subendothelial layer, where LDLs are trapped by binding to sticky matrix carbohydrates

44
Q

What is another name for the fat cells which macrophages phagocytose?

A

Oxidised LDLs

45
Q

What does the production of foam cells stimulate?

A

Chronic inflammation

46
Q

What is familial hyperlipidaemia?

A

Autosomal recessive genetic disease where people have massively elevated cholesterol

47
Q

What is familial hyperlipidaemia a failure of?

A

Failure to clear LDL from the blood

48
Q

What is often formed in familial hyperlipidaemia

A

Xanthoma - accumualtion of foam cells on the skin

49
Q

What are the clinical features of FH?

A

Xanthomas and Early atherosclerosis

50
Q

What are scavenger receptors on macrophages?

A

A family of pathogen receptors that accidentally bind to oxidised LDLs

51
Q

How does a macrophage react with arterial OxLDL?

A

With lower levels of arterial OxLDL macrophages can remove abnormal materials resulting in safe clearance and reverse cholesterol transport.
However with higher levels of OxLDL macrophages will activate ‘bug detector’ pathways leading to inflammation

52
Q

What receptors are responsible for the ‘bug detector’ pathways?

A

macrophage scavenger receptors (A and B)

53
Q

What does the scavenger receptor A bind to?

A

OxLDL and gram positive bacteria and dead cells

54
Q

What does the scavenger receptor B bind to?

A

OxLDL and malaria parasites and dead cells

55
Q

What do macrophages generate within plaques?

A

Free radicals

56
Q

What do the free radials do?

A

They further oxidise lipoproteins

57
Q

What are macrophages activated by?

A

Modified lipoproteins/free intracellular cholesterol

58
Q

What do activated macrophages secrete?

A

o Cytokine mediators that recruit monocytes
o Chemoattractants and growth factors for VSMC
o Proteinases that degrade tissue (e.g. the fibrous cap)
o Tissue factor that stimulates coagulation on contact with blood

59
Q

In atherosclerosis what happens to the foam cells?

A

They die by apoptosis by leave cytotoxic fat everywhere contributing to the lipid rich core of the plaque

60
Q

What is NADPH oxidase?

A

It takes oxygen and reduces it to form a superoxide (O2-)

61
Q

What is the superoxide used to form in macrophages?

A

Hypochlorous acid

62
Q

What is hypochlorous acid?

A

It is extremely toxic and is what activated macrophages secrete

63
Q

As the macrophages get further and further from the subendothelial layer what happens?

A

They get bigger and bigger bloated with fat until the fat comes out of solution forming fat globules killing the macrophage

64
Q

What are cytokines?

A

Protein immune hormones that activate endothelial cell adhesion molecules

65
Q

What is function of interleukin-1?

A

Upregulates vascular cell adhesion molecule-1 (VCAM-1)

66
Q

What is the function of VCAM-1?

A

Mediates right monocyte binding

67
Q

What occurs when there is reduced VCAM-1 and interleukin 1?

A

There is reduced atherosclorosis

68
Q

What are chemoattractants?

A

Small proteins chemoattractant to monocytes. E.g Monocyte Chemoattractant protein-1 (MCP-1)

69
Q

What does MCP-1 bind to?

A

Binds to a monocyte G-protein coupled receptor (CCR2)

70
Q

What occurs when there is reduced MCP-1 and CCR2?

A

There is reduced atherosclerosis

71
Q

What cell do macrophages recruit?

A

They recruit VSMC stimulate them to proliferate and deposit extracellular matrix

72
Q

What does increased deposition of collagen do?

A

Strengthens and stabilises the plaque

73
Q

How do macrophages recruit VSMC?

A

They release complementary protein growth factors

74
Q

What are the two main growth factors released by macrophages?

A

Platelet derived growth factor

Transforming growth factor beta

75
Q

What is the function of the platelet derived growth factor?

A
  • VSMC chemotaxis
  • VSMC survival - promotes survival of smooth muscle in the toxic environment
  • VSMC division
  • Attracts smooth muscle from the tunica media to the abnormal plaque
76
Q

What is the function of transforming growth factor beta?

A
  • Doesn’t keep them alive or make them divide but does stimulate increased collagen synthesis
  • This promotes plaque stabilisation
77
Q

What can influence VSMC to become the synthetic phenotype?

A

PDGF and TGF-beta

78
Q

What is normal phenotype of VSMCs?

A

Large number of contractile filaments

Low number of matrix deposition genes

79
Q

What is the synthetic phenotype of VSMCs (atheroclerotic)?

A

Low number of contractile filaments

Large amount of matrix deposition

80
Q

How do macrophages affect the extracellular matrix?

A

They degrade plaque collagen

81
Q

How do macrophages degrade plaque collagen?

A

Matrix metalloproteinases

82
Q

What does the degradation of plaque collagen cause?

A

Weakens the fibrous cap so that it may rupture causing thrombus formation

83
Q

What are the features of a rupture prone plaque?

A

1) Large soft eccentric lipid-rich necrotic core
2) Thin fibrous cap
3) Reduces VSMC and collagen content
4) Increased VSMC apoptosis
5) Infiltrate of activated macrophages expressing MMPs

84
Q

What does a thin fibrous cap always mean?

A

Reduced collagen content

85
Q

What is nuclear factor kappa B?

A

Transcription factor and master regulator of inflammation

86
Q

What is nuclear factor kappa B activated by?

A

o Scavenger receptors
o Toll-like receptors
o Cytokine receptors

87
Q

What does nuclear factor kappa B switch on?

A

o Matrix metalloproteinases

o Inducible nitric oxide synthase

Year 1: Cardiovascular System (21 decks)

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