Mi4 - Induced Innate Immunity 1 (Barnett)

What does CD14 (found on what type of cell) bind?

CD14 on neutrophils and macrophages will bind LPS & other PAMPs

Which receptors recognize organisms other than bacteria? Which type of organisms? What molecule recognized?

CR-3&4 and Dectin-1 both recognize B-glycans on FUNGI TLRs recognize a specific wide variety of pathogen CRaving DonuTs the rest all recognize bacteria

Which receptor(s) do NOT recognize LPS?

CR-3&4, Dectin-1, and SR-B (CD36)

Which receptor(s) recognize oligosaccharides?

CR3&4

What is the end goal of TLR4 recognition of LPS?

Goal == activate NFkB to initiate transcription of inflammatory cytokines for the macrophage to release

Describe the structure of toll-like receptors (TLRs).

Homodimer with pathogen recognizing domain and toll-interleukin receptor (for signaling)

Where does the CXCL8 for extravasation come from?

macrophages primarily but once neutrophils bind CXCL8 outside of vasculature, they will also produce CXCL8

CD206 aka?

mannose receptor

Which type of bacteria all have LPS?

(-) gram-NEGATIVE (-)

What are found in secondary granules?

- NAPDH oxidase components -> H2O2 - Lactoferrin - lysozyme

Now that LPS has been recognized by TLR4/MD2/CD14, what happens?

1) Activate IKK (reminder- MITI) -- a. MyD88 binds TIR domain on TLR4 -- b. MyD88 phosphorylates IRAK4 -- c. IRAK4 phosphorylates TRAF6, which then initiates a kinase cascade to eventually activate IKK 2) Activate NFkB by removing it's inhibitor (IkB) -- IkB is inactivated by phosphorylation from IKK 3) NFkB initiates transcription of inflammatory cytokines

What's the first step in neutrophil extravasation?

1) Margination --- get neutrophils in blood stream close to ECs via vasodilation

What happens to dying neutrophils?

1) Netosis == form extracellular traps (NETs) to catch bacteria and viruses (NETs have defensins, proteases, and calprotectin) 2) Apoptosis & phagocytosis by macrophages (the garbage bag)

What are the three types of granules found in neutrophils?

1) azurophilic (primary) granules 2) secondary granules 3) tertiary granules

What is the purpose of IL-12?

1) recruit and activate NK cells to secrete more inflam cytokines & further activate macrophages 2) convert T-cells -> Th1 cells

Second step in neutrophil extravasation? Is this a strong or weak interaction? What receptors/ligands are on the neutrophil to allow for this? What about endothelium?

2) Rolling --- hit the "speed bumps" to slow down -- neutrophil rolls along endothelium because of weak interactions of it's sLex with E & P-selectin on ECs -- weak --> tight interactions (STOP ROLLING) when neutrophil interacts with inflam cytokine CXCL8 now time for step 3.. (these two steps blend together really..) Neutrophil: CXCL8 receptor, sLex EC: E&P-selectins

After tightly binding to EC, explain the rest of WBC extravasation. Be specific with molecules and where they are located.

3) Adhesion via CAMs -- Neutrophil's LFA-1 & CR3 bind with ICAM1&2 on endothelial cell 4) Extravasation across post-cap VENULES -- b/c the CXCL8 gradient is higher outside the vasculature, the neutrophil pushes through endothelium so it can bind -- Need CD31, LFA-1, and CR3 Finito!

What are found in azurophilic granules?

AMPs - Myeloperoxidase (MPO) - Defensins - Lysozyme - Neutral proteases - 'bactericidal permeability-increasing protein' - binds LPS

How does CXCL8 cause neutrophils to tightly adhere to EC?

B/c CXCL8-R is a GCP (as are most cytokine receptors), it causes transcriptional activation that changes the conformation of LFA-1 and CR-3, which allows them to bind more tightly to ICAM1&2 & therefore, you get strong neutrophil binding

Which receptor(s) recognize mycobacterial ligands?

Dectin-1

Know that chart

Did not include everything in these flashcards look at printout for it to match your pneumonic

What is the purpose of IL-6?

FEVER induces fat and muscle to metabolize to make heat and raise the temp in infected tissue IL-6

What type of receptor is CXCL8 receptor (found on what type of cell)?

GCP neutrophil

What are found in tertiary granules? Function?

Gelatinase -- sequesters iron like lactoferrin

Which CAMs are found on ECs?

ICAM-1 & Vascular addressins

What are the 5 inflammatory cytokines macrophages secrete?

IL-1 IL-6 IL-12 TNF-alpha CXCL8

Which inflam cytokines are vital for WBC extravasation and why?

IL-1 & TNF-alpha increases vascular permeability & CXCL8 for travel through EC

What are inflammasomes? Main purpose? Which is most important inflammasome?

Inflammasomes respond to a variety of different microbes but ultimately will activate capases to cleave pro-IL-1B to activate IL-1B NRLP3

How is IL-1B production amplified?

It amplifies itself!!

Which CAMs are found on leukocytes?

L-selectin & Integrins

L-selectins on (WBC or EC) will bind which CAM? What about integrins?

L-selectins on WBC will bind vascular ADDRESSINs "Select & Address to Stick" Integrins on WBC --- ICAM1 "I&I"

What does TLR4 recognize?

LPS

CD14 aka?

LPS receptor

In macrophages, what can the bacterial degradation products elicit? How?

MORE INFLAM CYTOKINE PRODUCTION by activating NFkB 1) degradation product is recognized by NOD receptor 2) NOD receptor binds RIPK2 3) RIPK2 phosphorylates TAK1, which in turn eventually leads to NFkB activation Degradation products === NOD, RIPK2, TAK1

Explain respiratory burst. Include where things come and what happens to pH as you proceed.

NADPH + O2 -- (NADPH oxidase) --> O2- --(Superoxide dimutase) --> H2O2 --(myeloperoxidase or catalase)--> HOCl or H20 + O2 (respectively) pH continually rises as this process occurs and destroys engulfed bacteria NADPH is always in neutrophils NADPH oxidase comes from secondary granules MPO from azurophilic

What test can you use to diagnose chronic granulomatous disease?

NBT (Nitroblue-tetrazolium) test

What is NEMO?

NFkB Essential Modulator ---- inhibits IkB kinase NEMO inhibits the activator of IkB (which inhibits NFkB) Activator of IkB = IkB kinase therefore, NEMO allows for NFkB activity & you get transcription! :D

How do we end up with active IL-1B from activation of NRLP3?

NRLP3 combines with an adaptor protein and procapase 1 ---> activate capase 1 Capase 1 will cleave pro-IL-1B --> IL-1B

How is LPS recognized by macrophage?

Need two membrane receptors == CD14 & TLR4 1) LBP (LPS binding protein) finds LPS and brings it to TLR4/MD2 and CD14 complex MD2 is a protein associated with TLR4 that confers LPS sensitivity

What are the first effector cells to a site of injury/infection?

Neutrophils

What mediates P-selectin? E-selectin?

P-selectin === histamine E-selectin -- TNF-alpha & IL-1

What's the purpose of CXCL8?

Recruit & guide neutrophils to infected tissue

Which receptor(s) recognize CpG islands on DNA?

SR-A

CD36 aka?

SR-B

Which receptor is not phagocytic but rather for signaling?

TLRs (toll-like receptors)

What induces ICAM-1&2 expression?

TNF-alpha

What is chronic granulomatous disease? What does it cause?

X-linked mutation in NADPH oxidase low respiratory burst and reduced ROS susceptible to catalase + organisms (chronic bacterial and fungal infections)

Which type of toxin is LPS?

endotoxin produced by bacteria

What holds together these granules?

proteoglycans

What happens in NEMO deficiency? What do patients present with?

reduced activation of NFkB & therefore, reduced inflam cytokine release ----->> chronic bacterial and viral infections ++ developmental defects Commonly present with conical or missing teeth

Know the chart of macrophage receptors!!

see questions at end of this deck

What does lactoferrin do?

sequesters iron required by bacteria (bacteria need iron to divide, so this is beneficial)

Last couple slides of this lecture give clinical example

slides 30-33