Innate Immunity - Early Recognition (3) Flashcards

1
Q

Where are sentinel cells present?

A

in tissues
under epithelium
along vessels
within epithelium of mucosal surfaces

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2
Q

What do sentinel cells recognize?

A

invading microbes (pathogens)

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3
Q

List the types of sentinel cells

A

mast cells
macrophages
dendritic cells

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4
Q

How do sentinel cells recognize pathogens?

A

they have pattern recognition receptors (PRRs) that recognize these alarm signals

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5
Q

Pattern recognition receptors are on ______

A

sentinel cells

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6
Q

What are the alarm signals for sentinel cells?

A

pathogen-associated molecular patterns (PAMPs)
damage-associated molecular patterns (DAMPs)

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7
Q

Invading microorganisms are [exogenous/endogenous] alarm signals, and dead or dying host cells are [exogenous/endogenous] alarm signals

A

microorganisms: exogenous
dying host cells: endogenous

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8
Q

What is another word for DAMPs?

A

alarmins

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9
Q

Recognition of pathogens by sentinel cells leads to activation of ________

A

the innate immune system

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10
Q

List an example of a PAMP

A

bacterial lipopolysaccharides
bacterial peptidoglycans
bacterial DNA
viral nucleic acids

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11
Q

Gram [+/-] bacteria contains lipopolysaccharides

A
  • negative
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12
Q

Does Gram-+ or Gram - have thick peptidoglycan walls?

A

+ positive

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13
Q

Which type of acid is in Gram + bacteria?

A

lipotechoic acid

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14
Q

_______ acid acts as a PAMP in acid-fast bacteria

A

Mycolic

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15
Q

DAMPs are released when cells _____ or when ________ is damaged

A

die (intracellular)
connective tissue (extracellular)

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16
Q

When host cells die, damaged mitochondria may be recognized as _____ they once were. Why?

A

bacteria
mitochondrial DNA resembles bacterial DNA, which is rich in unmethylated CpG

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17
Q

Bacterial DNA is rich in _______

A

unmethylated CpG (like mitochondrial DNA)

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18
Q

HMGB1 is an [extracellular/intracellular] DAMP

A

intracellular

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19
Q

What is the significance of HMGB-1 as a DAMP?

A

released when cells are damaged
recognized by sentinel cells leading to inflammation - activates a series of reactions

20
Q

What does HMGB-1 target?

A

endothelium
macrophages
neutrophils
dendritic cells
epithelium

21
Q

What are the characteristics/types of PRRs on sentinel cells?

A

soluble
within vesicles
cytoplasmic
membrane-bound

22
Q

What are toll-like receptors? What are they present on?

A

transmembrane glycoprotein receptors
present on sentinel cells and others

23
Q

What is the role of toll-like receptors?

A

play a critical role in microbial sensing by recognizing bacteria, fungi, and viruses

24
Q

Where are toll-like receptors located?

A

some ON the cell surface
some WITHIN the cell

25
Q

Toll-like receptors on the cell surface recognize [extracellular/intracellular] invaders such as bacteria and fungi.

A

extracellular

26
Q

Toll-like receptors within the cell recognize [extracellular/intracellular] invaders such as viruses.

A

intracellular

27
Q

List the cell-surface toll-like receptors (TLRs) that mainly recognize bacterial and fungal proteins, lipoproteins, and LPS

A

TLRs 1, 2, 4, 5, 6, 11 (extracellular)

28
Q

List the intracellular TLRs that recognize viral and bacterial nucleic acids

A

TLRs 3, 7, 8, 9, 10

29
Q

TLR 8 recognizes which pathogens?

A

intracellular:
viruses, bacterial nucleic acids

30
Q

TLR 4 recognizes which pathogens?

A

extracellular:
bacterial and fungal proteins
lipoproteins
LPS

31
Q

TLR 5 recognizes which pathogens?

A

extracellular:
bacterial and fungal proteins
lipoproteins
LPS

32
Q

What happens when a PAMP binds to a TLR?

A

activates transcription factors to transcribe cytokine genes
results in inflammation

33
Q

Describe TLRs and diarrhea in German Shepherds regarding inflammatory bowel disease

A

they can have single nucleotide polymorphisms in the TLR 4 and TLR 5 genes (extracellular)
so they have reduced ability to defend against bacterial invasion
results in predisposition to enteric infections

34
Q

Which TLR(s) are defective in inflammatory bowel disease in German Shepherds?

A

TLR 4
TLR 5

35
Q

What is RIG-1-like receptors?

A

retinoid acid inducible gene-like receptors - another family of PRRs expressed within the cytosol

36
Q

What do RIG-1-like receptors recognize?

A

viral dsRNA

37
Q

What does RLRs activate and trigger? What is the product?

A

activate: caspase
trigger: signaling pathways
product: type 1 interferons (IFN)

38
Q

What are NOD-like receptors?

A

PRRs that can detect pathogens within the cytosol

39
Q

What does NOD stand for?

A

nucleotide-binding oligomerization domain

40
Q

NOD1 recognizes _______, and NOD2 recognizes _______ and serves as a general sensor of ________

A

1: bacterial peptidoglycans
2: muramyl dipeptide
serves as general sensor of intracellular bacteria

41
Q

Binding to NLR activates the ______ pathway and triggers the production of _______

A

NF-B pathway
pro-inflammatory cytokines

42
Q

NOD2 also triggers production of _______, which are _______

A

defensin: antimicrobial proteins

43
Q

TLRs are characterized as _______

A

endosomal
extracellular
cytosolic

44
Q

NOD-like receptor, RIG-like receptor, and cytosolic DNA sensor are characterized as ______

A

cytosolic

45
Q

Both PAMPs and DAMPs bind to either ______ on ________ or ________

A

pattern-recognition receptors (PRRs)
cell surfaces or located within cells

46
Q

What is the major group of PRRs?

A

toll-like receptors

47
Q

What do cytokines do?

A

trigger local increases in blood flow
attract neutrophils
increase blood vessel permeability, allowing antimicrobial molecules and cells to flood affected tissues