Lecture 4 - Innate Immunity (Part I) Flashcards Preview

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Flashcards in Lecture 4 - Innate Immunity (Part I) Deck (14)
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1
Q

What are PAMPs?

L4 S9

A

Pathogen-associated molecular patterns

-Ags common to pathogens that have no structural similarity to self Ags

Examples:

  • mannose-tailed glycans
  • proteins starting with fMet
2
Q

What are PRRs?

L4 S9

A

Pattern recognition receptors

  • recognize PAMPS
  • stimulate phagocytosis and killing of bacteria
3
Q

What are TLRs and what do they do?

L4 S15,24

A

Toll-like receptors; class of PRRs

  • expressed on monocytes, neutrophils, Mφ, and DCs
  • activate NF-κΒ or IRF pathways which produce pro-inflammatory factors

-can cause host tissue injury and septic shock

4
Q

What are the pathways activated by TLRs and what gene products do they produce?
Which TLRs activate each pathway?

L4 S22

A

TRIF:

  • IRF: interferon regulatory factors
  • TLR 3 and TLR4

MyD88:

  • NK-κB: nuclear factor κB
  • TLR1/2, TLR2/6, TLR4, TLR5, TLR 7, TLR 8, and TLR 9

*note: TLR 4 is the only that uses both and TLR3 is only TRIF, all others are MyD88 only

5
Q

What TLR receptors are there, what are their ligands, and what organism are the specific for?

L4 S20 (The table on this slide is VERY useful)

A

TLR1/2 heterodimer:

  • lipopeptides/bacteria
  • GPI/parasites

TLR2/6 heterodimer:

  • lipoteichoic acid/gram-positive bacteria
  • zymosan/yeast (fungi)

TLR3:
-DS-RNA/viruses

TLR4/4 homodimer:
-lipopolysaccharide/gram-negative bacteria

TLR5:
-flagellin/flagellated bacteria

TLR7 and TLR8:
-SS-RNA/viruses

TLR9:
-unmethylated CpG-rich DNA/bacteria

6
Q

What are NOD-like receptors and what do they do?

L4 S28

A

Nucleotide oligomerization domain-like receptors; class of PRR

Respond to intracellular DAMPs and PAMPs to form a signaling complex, the inflamasome, which activates caspase-1 and in turn IL-1β and IL-18. End result is programmed cell death, pyroptosis.

7
Q

What is the SR family and what do they do?

L4 S32-33

A

Scavenger receptor; class of PRR

Three classifications:

  • Scavenger receptor class A type I
  • Scavenger receptor class A type II
  • MARCO (macrophage receptor with collagenous structure)

Typically found on immune cells, most notably MΦ.

Bind bacterial components based on negative charges and induce phagocytosis.

Play a role in tissue remodeling after damage from inflammation/infection.

8
Q

What are the structures of the different SR family protiens?

L4 S33

A

Trimeric complex of transmembrane polypeptides

Consists of combination of 3 potential domains:
-SR cysteine-rich (SRCR) domain
—absent in SR-A II
-collagen-like domain (polyanionic binding region)
-α-helical coiled-coil domain
—absent in MARCO

9
Q

What is the lectin family and what do they do?

L4 S36-37

A

C-type lectin family:
-bacterial carbohydrate recognition domain

Can be soluble or membrane bound.

Facilitate phagocytosis, stimulate secretion of cytokines, complement activation.

10
Q

What are DAMPs?

L4 S39-40;42

A

Damage associated molecular patterns

Factors normally only found inside cells that are released due to necrotic cell death and induce inflammation.

Includes:

  • nucleic acids
  • certain lipids
  • certain intracellular proteins (HMGB1 and HSP)

Activates NF-κB pathway

11
Q

What are the characteristics of inflammation and what causes them?

L4 S40

A

Characteristics:

  • redness
  • heat
  • swelling
  • pain
  • loss of function

Caused by:

  • increased blood supply
  • increased capillary permeability
  • influx of neutrophils
  • arrival of monocytes/MΦ (16-48 hrs)
12
Q

What are defensins?

L4 S45

A

Antimicrobial peptides produced by epithelial cells, PMNs, NKs, and CTLs.

Stimulated by cytokines and PRR activation.

Kill microbes by inserting into membranes and disrupting function.

Regulate immune cell function and inflammatory response.

13
Q

What are cathelicidins?

L4 S46

A

Antimicrobial peptide produced by epithelial cells and PMNs.

Stimulated by cytokines and PRR activation.

Varying mechanisms of activity:

  • binding and neutralizing LPS
  • can block inflammasome activation
14
Q

What are NK cells and what is their function?

L4 S49

A

Recognizes and kills infected cells or stressed cells. This helps to eliminate infectious reservoirs and releases pathogens for phagocytosis.

Respond to IL-12 released by MΦ and in turn releases IFN-γ to tell MΦ to kill phagocytized microbes.

Process is inhibited by the presence of MHC class I.