signalling defects in innate immunity

Question 1

What receptor is homologous to TLRs? And what is the Extracellular and intracellular structure of TLRs like?

Answer 1

IL-1 receptor is homologous.

TLRs have many LRRs, and cytoplasmic tail with TIR domain for phosphorylation cascades.

Question 2

Broad categories that TLRs bind?

Answer 2

lipids, proteins and nucleic acids.

Question 3

What does TLR4 classically bind and what RSV antigen might stimulate it? What self proteins may also stimulate it?

Answer 3

LPS, RSV fusion protein may stimulate it (controversy due to contamination?)

Heat shock proteins may also stimulate them and are associated with damage.

Question 4

What main ligands for TLR2?

Answer 4

lipoproteins and lipoteich acid and peptidoglycan.

Question 5

What does TLR3 bind in endosomes?

Answer 5

dsRNA.

Question 6

What do TLR7 and TLR8 bind?

Answer 6

ssRNA in endosomes.

Question 7

What does TLR9 bind?

Answer 7

CpG-containing DNA motifs which are unmethylated.

Question 8

ligand for TLR1?

Answer 8

lipopeptides and lipoproteins.

Question 9

What does TLR5 bind?

Answer 9

flagellin.

Question 10

What are important adaptor molecules downstream of TLRs and IL-1Rs?

Answer 10

MyD88 and downstream IRAK4 and IRAK-1.

Question 11

What does activation of IRAKs stimulate?

Answer 11

release of NF-kB from IkB, and its translocation into the nucleus. Upregulate IL6, Il1 and TNFa.

Question 12

What adaptor and downstream moelcules used by TLR3 (and TLR-4) to stimulate type 1 IFNs?

Answer 12

TRIF to Ikk(epsilon) and TBK1 which activates IRF3 type 1 interferon production.

Question 13

What components are part of the complex that is responsible for Ik-B phosphorylation and release of NF-kB?

Answer 13

IKK complex-
Ikk-y (NEMO)
Ikk-a and Ikk-beta.

Question 14

What can deletion of NEMO exons (on X chromosomes) cause in male and females?

Answer 14

males causes letahlity.
females it causes incontentia pigemneti.
Associated with abnormalities in ectodermal derived tissue (CNS teeth skin and eyes).
swirling pattern develops to blisters and sores on skin.

Question 15

Whats the result of hypomorhpic mutations in NEMO in men>

Answer 15

Reduced activation of NEMO (can be very variable caused by many different mutations).
Females aren’t symptomatic.

Males it causes EDA with immunodeficiency.
(ectoderm derived tissue abnormalities) concical teet,h, dry heat intolerant skin, saprse hair growth.

Question 16

What kind of infections are patients with NEMO deficiency susceptible to?

Answer 16

bacterial infections, espcially pyogenic ones.

Especially mycobacterial ones, and indicator is BCGosis.

Question 17

Where is the autosomal dominant mutation for NEMO?

Answer 17

within IkB, specifically the IkBa, which inhibtis its ability to be phosphorylated, ubuquitinted and degraded.
Nf-kB not released.

Question 18

Is IRAk-4 X linked/ autosomal dominant/ autosomal recessive?

Answer 18

It is autosomal recessive, many mutations result in premature stop codon maybe a result of a founder effect.

Question 19

Some symptoms of case study for IRAk 4 deficiency?

Answer 19

septic pustules and arthritis, lots of abscesses, and also meningitis.

Question 20

What kind of bacteria cause infection in IRAK-4 deficiency?

Answer 20

A wide range of differente pyogneic organisms e.g. staph, strep, shigp. aeurginosa and shigella.
These can disseminate and causes sepsis.

Question 21

when looking at the acute phase response (e..g in IRAk4 deficiency) what tests you look at?

Answer 21

Look a neutrophil counts to infection, as well as CRP and erythrocyte sedimentation rate (ESR- a marker of inflammation).

These will be decreased in IRAK4 deficiency

Question 22

What are expected results of Immunoglobulni tests and neutrophil responses for the IRAK4 patient?

Answer 22

Ig tests normal.
Neurophils NDT tests fine for PMA, but poor in response to LPS.
Poor chemotaxis in response to fMLP.

Question 23

What is morbidity and mortality like for IRAK4 deficiency patinests?

Answer 23

45% mortality at 10yo.

those that survive often have neurological damage form dissmeinated infection.

Question 24

What simple screen is often used to test for IRAk 4 deficiency?

Answer 24

One colour flow for CD62L (L selectin) in neutrophils.

Normally expressed for rolling, but shed upon TLR activation.

Question 25

TLR agonists added to patient neutrohpils for CD62L shedding investigation?
Results for IRAK4 deficiency?

Answer 25

LPS, CLO97 (to stimulate TLR7/8 dimers) and PMA.

PMA - shedding seen (bypassed TLR signalling)
CLO97 no shedding.
LPS only some (due to TLR-4 signalling via TRIF).

Question 26

What are the symptoms of MyD88 deficiency?

Answer 26

Very similar to IRAK4 deficiency.

e.g. septic pustules and arthritis, lots of abscesses, and also meningitis.

Question 27

Do surviving IRAK4 and MyD88 patients improve symptomatically with age?

Answer 27

yes!

Question 28

As well as IRAK-4 and MyD88 deficiency, whats another classical TLR defect that affects the ER?

Answer 28

UNC-93B, which is thought to be involved in the presenting materials for TLR 3 7/8 and 9.

Question 29

How does the presentation of UNC-93B differ compared to the other TLR deficiencies?

Answer 29

Presents with viral (rather than bacterial) infections.

Characteristically herpes simplex virus-1 encephalitis.

Question 30

What other mutations are linked with herpes simplex encephalitis (HSE)? Are they autosomal recessive or dominant?

Answer 30

Mutations affecting the TLR3 pathway.
e.g. AR and AD TLR3 mut.

AR and AD TRIF mutations.

AD mutation in TRAF3

AD mutations in TBK1.

Question 31

What was the controversial homozygous polymorphism in female who had history of stph sepsis and pneumonia at 3 months old?

Answer 31

loss of function TIRAP (adaptor linked to TLR2 and 4) polymorphism.

Showed incomplete penetrance as many other family members had same genotype but no phenotype.

Question 32

What three domains does NLRP/ NALP have?

Answer 32

NOD domain, LRR and PYD protein.

Question 33

What 3 kinds of Nod like receptors are there?

Answer 33

NLRP/ NALPs,

NOD proteins,

IPAF+ NAIP.