Lecture 3 - Early Recognition of Foreign Invaders Flashcards

1
Q

What cells recognize alarm signals?

A

sentinel cells

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2
Q

What do sentinel cells have that recognize alarm signals?

A

pattern recognition receptors

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3
Q

Alarm signals are generated by what 2 things

A
  1. invading microorganisms (PAMPs)
  2. dead or dying host cells (DAMPs or Alarmin)
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4
Q

What are exogenous signals

A

PAMPs

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5
Q

What are endogenous signals

A

DAMPs or Alarmins

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6
Q

Recognition of pathogens by sentinel cells leads to activation of …

A

innate immune system

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7
Q

What are PAMPS

A

conserved molecular structures or patterns that occur in a diverse range of potential microbial invaders

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8
Q

Examples of PAMPs

A
  1. bacterial lipopolysaccharides
  2. bacterial peptidoglycans
  3. bacterial DNA
  4. viral nucleic acids
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9
Q

What is another name for LPS

A

endotoxin

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10
Q

What bacteria have LPS

A

gram-negative

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11
Q

What bacteria have peptidoglycan

A

gram-positive

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12
Q

Why is bacterial DNA a PAMP

A

its unmethylated

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13
Q

What is the PAMP in gram-negative bacteria

A

LPS

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14
Q

What is the PAMP in gram-positive bacteria

A

peptidoglycan

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15
Q

What is the PAMP in acid fast bacteria

A

mycolic acid

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16
Q

When are intracellular DAMPS generated

A

released when cells die

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17
Q

When are extracellular DAMPs generated

A

connective tissue is damaged

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18
Q

Why might damaged mitochondria from dead host cells be recognized as bacteria?

A

DNA resembles bacterial DNA, which is rich in unmethylated CpG

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19
Q

Examples of extracellular DAMPs

A

-hyaluronic acid
-heparan sulfate
-fibrinogen
-collagen-derived peptides
-fibronectin
-laminin
-elastin

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20
Q

Examples of intracellular DAMPs

A

-HMGB1
-uric acid
-chromatin
-andenosine
-galectin
-S100 proteins
-cathelicinds
-defensins
-N-formyl peptides
-lactoferrin
-heat-shock proteins

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21
Q

What is an important intracellular DAMP

A

HMGB1

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22
Q

What is the main affect of HMGB1?

A

inflammation; tissue damage

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23
Q

What is the adverse effect of too much HMGB1

A

shock

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24
Q

What types of PRRs soluble

A

-collectins
-ficolins
-complement
-pentraxins

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25
Q

What PRRs are within vesicles

A

-TLR 3, 7, 8, 9

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26
Q

Whaat PRRs are cytoplasmic

A

-Rig-1
-NOD-like
-peptidoglycan receptors
-DNA receptors

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27
Q

What PRRs are membrane-bound

A

-TLRs
-Lectins
-Mannose receptor
-Langerin
-Dectins
-Scavenger receptors
-intergrins

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28
Q

What are the most important PPRs

A

TLRs

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29
Q

What type of receptors are TLRs

A

transmembrane proteins

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30
Q

List the 3 PRR receptors

A
  1. toll-like receptors
  2. retinoic acid inducible gene (RIG)-1like receptors
  3. nucelotide-binding oligomerization domain (NOD)-like receptors (NLRs)
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31
Q

What do TLRs play a critical role in sensing?

A

bacteria, fungi, viruses

32
Q

What do TLRs located on the cell surface recognize?

A

extracellular invaders such as bacteria and fungi

33
Q

What do TLRs located within cells recognize

A

intracellular invaders such as viruses

34
Q

How many TLRs do mammals possess

A

10-12

35
Q

What TLR do humans and cattle have

A

TLR1-TLR10

36
Q

What TLR do mice have

A

TLR 1-13 EXCEPT TLR10

37
Q

What are the cell surface TLRs

A

1, 2, 4, 5, 6, 11, 12

38
Q

What do cell surface TLRs recognize

A

bacterial and fungal proteins, lipoproteins, and LPS

39
Q

What do intracellular TLRs recognize

A

viral and bacterial nucleic acids

40
Q

What are the intracellular TLRs

A

3, 7, 8, 9, 10, 13

41
Q

TLR1 ligand

A

triacylated lipoprotein

42
Q

TLR2 ligand

A

lipoproteins

43
Q

TLR3 ligand

A

dsRNA

44
Q

TLR4 ligand

A

LPS

45
Q

TLR5 ligand

A

flagellin

46
Q

TLR6 ligand

A

diacylated lipoprotein

47
Q

TLR7 ligand

A

ssRNA, guanosine

48
Q

TLR8 ligand

A

ssRNA

49
Q

TLR9 ligand

A

CpG DNA, dsDNA

50
Q

TLR10 ligand

A

regulates TLR2 responses

51
Q

TLR11 ligand

A

profilin and flagellin

52
Q

TLR12 ligand

A

profilin

53
Q

TLR13 ligand

A

unmethylated RNA

54
Q

TLR1 pathogens recognized

A

bacteria

55
Q

TLR2 pathogens recognized

A

bacteria, viruses, parasites

56
Q

TLR3 pathogens recognized

A

viruses

57
Q

TLR4 pathogens recognized

A

bacteria, viruses

58
Q

TLR5 pathogens recognized

A

bacteria

59
Q

TLR6 pathogens recognized

A

bacteria, viruses

60
Q

TLR7 pathogens recognized

A

viruses, bacteria

61
Q

TLR8 pathogens recognized

A

viruses, bacteria

62
Q

TLR9 pathogens recognized

A

viruses, bacteria, protozoa

63
Q

TLR10 pathogens recognized

A

suppresses inflammation

64
Q

TLR11 pathogens recognized

A

protozoa, bacteria

65
Q

TLR12 pathogens recognized

A

protozoa

66
Q

TLR13 pathogens recognized

A

bacteria

67
Q

What receptors bind to HMGB1

A

RAGE

68
Q

What is the signal cascade when LPS binds to a TLR

A

upregulate caspase 1 to act on ProTNF, ProIL-1, Pro-IL6 to turn into active form

69
Q

Why is IBD common in GSDs?

A

single-nucleotide polymorphisms (SNPs) in TLR4/5 genes are common in GSDs, which reduces ability to defend against bacterial invasion resulting in predisposition to enteric infections

70
Q

What do RIG-1-like receptors recognize

A

viral dsRNA

71
Q

What happens after RLRs are activated

A

activate caspase and trigger signaling pathways, leading to production of type 1 interferons (IFN)

72
Q

What do NOD1 receptors recognize

A

bacterial peptidoglycans

73
Q

What do NOD2 receptors recognize

A

muramyl dipeptide and serves as a general sensor of intracellular bacteria

74
Q

What does binding to NLR activates?

A

NF-B pathway and triggers production of proinflammatory cytokines

75
Q

What does NOD2 also trigger production of

A

defensins

76
Q

What are defensins

A

antimicrobial proteins