Inflammation Flashcards

1
Q

What is inflammation?

INTRO

A

protective biological process designed to remove damaged cells + clear threats such as infections and toxins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What cells does inflammation involve?

A

not only cells at the site of damage but also the recruitment immune cells, fluid and molecular components from the circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How is inflammation initiated?

A
  • when cellular damage (non-apoptotic cell death) leads to the release of damage associated molecular patterns (DAMPs) or
  • the body detects pathogen associated molecular patterns (PAMPs)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the release of DAMPs and PAMPs cause?

A

causes the cells in the damaged tissue to secrete a range of signals designed to induce inflammation including molecules that alter the structure of nearby blood vessels and chemokines that promote the recruitment of immune cells to the site of injury

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the aim of immune cell recruitment?

A

to clear the source of the initial inflammatory signal, and eventual resolution and repair of the inflamed tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How is the majority of inflammation categorised?

A

acute, with a rapid onset and resolution, and characterised primarily by the recruitment of innate cells into the tissue, in particular neutrophils

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

When can the state of chronic inflammation occur?

A

If the acute inflammatory response cannot remove the inflammatory stimuli however then other immune cells including adaptive immune cells are recruited

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the difference between acute inflammation and chronic inflammation?

A

acute inflammation often resolves without any substantive damage to the surrounding tissue
– chronic inflammation can lead to repetitive rounds of inflammation, tissue damage and repair, resulting in scarring and loss of tissue function.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is inflammation?

A

non-specific response to cellular injury

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the role of inflammation?

A

to remove the cause and consequence of injury

universal process in health and disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the 4 main signs of acute inflammation?

A
  • redness (RUBOR)
  • heat (CALOR)
  • swelling (TUMOR)
  • pain (DOLOR)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the causes of inflammation?

A
  • Pathogens
  • Allergens
  • Auto-antigens
  • Physical damage
  • Extreme temperatures
  • Non-apoptotic cell death
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What cell types can be inflamed?

A

any cell types from epithelial and endothelial to specialised blood cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Inflammation is a universal process

A

immunity and infection
haematology
cell biology
genetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the pathway of inflammation?

A

change in local blood flow

structural changes in the microvasculature

recruitment/ accumulation of immune cells + proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the structure the skin?

A
epithelium
interstitium (mast cells + macrophages)
vascular endothelium (leukocytes + neutrophils)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What happens when theres a wound?

A
  1. inflammatory signals
  2. vasodilators released
  3. vascular changes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the inflammatory signals?

A
  • non-apoptotic cell death

- detection of foreign material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What vasodilators are released?

A
  • histamine

- nitric oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What vascular changes occur?

A
  • increased permeability
  • dilation
  • reduced flow
  • plasma leakage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the benefits of increased vascular permeability and leakage?

A

more antibodies
more protein
more barrier
more leukocyte migration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is histamine?

A

sources: mast cells, basophils, platelets
actions: vasodilation, increased vascular permeability, endothelial activation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are prostoglandins?

A

sources: mast cells, leukocytes
actions: vasodilation, pain, fever

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are cytokines? (TNF, IL-1)

A

sources: macrophages, endothelial cells and mast cells
actions: endothelial activation (adhesion molecules), fever, malaise, pain, anorexia, shock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are chemokines?

A

sources: leukocytes, activated macrophages
actions: chemotaxis, leukocyte activation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are complement? (C5a, C3a, C4a)

A

sources: plasma (produced in the liver)
actions: leukocyte chemotaxis and activation, vasodilation (mast cell stimulation), opsonisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is exudate?

A

Fluid, proteins and cells that have seeped out of a blood vessel

28
Q

how are immune cells recruited?

A
  1. Recruitment and inflammation signals at the site of damage e.g. chemokines produced
  2. Chemokines diffuse out to form a gradient
  3. Leukocytes expressing complementary chemokine receptors migrate toward the chemokine source
29
Q

What is often the first cell type recruited to the site of inflammation?

A

neutrophils

30
Q

What is the 4 step process of neutrophil extravasation?

A
  1. Chemo-attraction
  2. Rolling adhesion
  3. Tight adhesion
  4. Transmigration
31
Q

What happens during chemo-attraction?

A

Cytokines -> endothelial upregulation of adhesion molecules e.g. selectins

32
Q

What is rolling adhesion?

A

Carbohydrate ligands in a low affinity state on neutrophils bind selectins
e.g. PSGL1 (selectin P ligand) binds P and E-selectins

33
Q

What is tight adhesion?

A
  • Chemokines promote low to high affinity switch in integrins LFA-1, Mac-1 – enhance binding to ligands e.g. ICAM-1/2
34
Q

What is transmigration?

A
  • Cytoskeletal re-arrangement and extension of pseudopodia. Mediated by PECAM interactions on both cells.
35
Q

What is the neutrophil function at the site of inflammation?

A
  1. Pathogen recognition
  2. Pathogen clearance
  3. Cytokine secretion.
36
Q

How do neutrophils recognise pathogens?

A

e.g. use of TLR4 and CD14 to identify lipopolysaccharides (LPS) present in gram-negative bacteria

37
Q

What is pathogen clearance?

A

Phagocytosis

Netosis

38
Q

What is cytokine secretion?

A

Recruitment and activation of other immune cells

39
Q

What is phagocytosis?

A
  • Large particles engulfed into membrane bound vesicles (phagosomes)
  • Phagosome fuses with lysosome (vesicles containing enzymes e.g. elastase and lysozyme) -> phagolysosome
  • Ractive oxygen species (ROS) – phagocyte NADPH oxidase
  • Antimicrobial peptides – e.g. defensins.
40
Q

What is the resolution of acute inflammation?

A
  1. pathogen recognition
  2. short half life
  3. macrophages
  4. repair/ wound healing
41
Q

What is an antigen?

A

a molecule or molecular structure that can be recognised by an antibody
or
any substance to which your immune system can mount an antibody or adaptive immune response

42
Q

What are the antigen types?

A
  • foreign antigen
  • self antigen
  • immunogen
  • hapten
43
Q

What is a foreign antigen?

A

an antigen derived from molecules not found in the body

44
Q

What is a self antigen?

A

an antigen derived from molecules produced by our bodies

45
Q

What is an immunogen?

A

an antigen independently capable of driving an immune response in the absence of additional substances

46
Q

What is a hapten?

A

a small molecule that alone does not act as an antigen but when bound to a larger molecule can create an antigen

47
Q

Name some diseases characterised by chronic inflammation?

A

rheumatoid arthritis, asthma, inflammatory bowel disease, glomerulonephritis, hepatitis, psoriasis and multiple sclerosis

48
Q

Name some diseases associated with granulomatous inflammation?

A

tuberculosis and leprosy, foreign body granulomas, tumour reactions, sarcoidosis, Crohn’s disease

49
Q

How is chronic inflammation different from acute?

A
  • Persistent inflammatory stimuli
  • Distinct immune cell infiltrate
  • A vicious cycle
50
Q

What can cause persistent inflammatory stimuli?

A
  • persistent/prolonged infection (e.g. TB, hepatitis B/C)
  • Persistent toxic stimulii
    e. g. allergens, pollutants
  • Unclearable particulates e.g. silica
  • Autoimmunity e.g. self antigens
51
Q

What are the distinct immune cells that infiltrate during chronic inflammation?

A
  • Inflammatory macrophages
  • T cells (and other lymphocytes)
  • Plasma (antibody secreting) cells
52
Q

What does the visious cycle of chronic inflammation include?

A
  • No clearance of inflammatory agent
  • Bystander tissue destruction
  • Concurrent repair processes (fibrosis and angiogenesis)
53
Q

What are macrophages?

A

recruited as monocytes to the site of inflammation, but also tissue resident.

54
Q

Which are the good macrophages?

A

Phagocytic
Cytotoxic
Anti-inflammatory (e.g. TGF-β, IL-10)
Wound repair

55
Q

Which are the bad macrophages?

A

Cytotoxic
Inflammatory
Pro-fibrotic

56
Q

How are T cells involved in inflammation?

A
  • pro-inflammatory (e.g. TNF, IL-17, IFN-γ)
  • Cytotoxic (e.g. granzymes, perforin)
  • Regulatory (e.g. TGF-β)
57
Q

How are B cells involved in inflammation?

A
  • Generate plasma cells that secrete antibody.
  • Protective, clearing infection
  • Inflammatory, driving reactions against self
  • Can either be local to inflammatory site, or operate remotely
58
Q

What is granulomatous inflammation?

A
  • Chronic inflammation with distinct pattern of granuloma formation
59
Q

What is granulomatous inflammation triggered by?

A
Triggered by strong T cell responses. 
Resistant agents (e.g. mycobaterium, tumour)
60
Q

acute vs chronic inflammation

ACUTE

A
Acute:
- Immediate onset; lasts a few days
- Vasodilation, increased vascular permeability, leukocyte response
- Neutrophils predominate
- Histamine release
- Prominent necrosis
- Outcomes include:
Complete resolution
Progression to Chronic Inflammation
61
Q

acute vs chronic inflammation

CHRONIC

A
  • Delayed onset; may last weeks, months or years
  • Persistent inflammation, ongoing tissue injury, -attempts at healing
  • Monocytes / Macrophages predominate
  • Ongoing cytokine release
  • Prominent scarring
  • Outcomes include:
    Scarring
    Loss of function
62
Q

What are the sequelae of inflammation?

A

long term consequences

63
Q

What are the positive outcomes of acute inflammation?

A
  • clear inflammatory agent
  • remove damaged cells
  • restoration of normal tissue function
64
Q

What are the negatives of inflammation

A
  • excess tissue damage
  • scarring
  • loss of organ function –> organ failure
65
Q

What is wound healing?

A

leads to extracellular matrix (eg collagen) deposition

hard to remove collagen deposition(fibrosis) -> permanent scar

66
Q

What are the consequences of inflammation?

A
  • broncho-pneumonia
  • scarring
  • wound healing in sensitive tissue