1.07 Mucosal Immunology

Question 1

What kind of cells produce antimicrobial peptides in the intestinal lumen?

Answer 1

Paneth cells

Question 2

Where is secretory IgA produced at the intestinal mucosa?

Answer 2

Lamina propria (plasma cells)

Question 3

How are intestinal epithelial cells held together to maintain a first line of defense/physical barrier?

Answer 3

Tight junctions

Question 4

What are some immune stimuli that can increase mucin production?

Answer 4

IL1, IL4, IL6, TNFa, Interferons (Type 1)

Question 5

Intestinal epithelial cells produce what two anti microbial substances?

Answer 5

Paneth cells + defensins

Question 6

Why do IECs express TLR 2,4, 5, 6, 7, 9, and engage in signaling?

Answer 6

Increase tight junction strength, motility and replication, & defensin secretion

Question 7

Do IECs also have Nod like Receptors?

Answer 7

Yup to recognize pathogens

Question 8

When are TLR and NLR activated at IECs (why not all the time)?

Answer 8

TLR only activated past basolateral surface (past epi) and NLR only activated at cytosol

Question 9

What is included in the adaptive immune defense at the mucosa?

Answer 9

GALT, Peyer’s patches, mesenteric lymph node

Question 10

What’s in a Peyer patch?

Answer 10

B, T, DC cells and Macrophages

Question 11

What delivers antigens from lumen to GALT to be recognized by adaptive immune system?

Answer 11

M cells (with short irregular micro ills)

Question 12

Where does antigen presentation to the T cells happen?

Answer 12

Lymph nodes (GALT, Peyer, mesenteric)

Question 13

How are effector T cells distributed in the mucosa?

Answer 13

CD8 = epithelium (kill)
CD4 = peyers patches + nodes (orchestrate)

Question 14

Where do al the Th responses happen at mucosa?

Answer 14

Lamina propria

Question 15

What helps enhance fluid and mucus secretion, smooth muscle contraction, and bowel motility?

Answer 15

IL-4, IL-13

Question 16

What immune response against intestinal helminth infections?

Answer 16

Th2 (IL4, IL13, IgA)

Question 17

What immune response maintains mucosal epithelial barrier function?

Answer 17

Th17 (IL17, IL22, IgA)

Question 18

What process allows activated T cells to go from the mucosal Lamina propria to lymph nodes?

Answer 18

Imprinting

Question 19

What is essential to allow the expressions of integrins and chemokine receptors for imprinting process?

Answer 19

Retinoic acid (via DCs)

Question 20

What immune responses is typically found in the gut?

Answer 20

Th2 (immunosuppressive)

Question 21

What kind of cells are found in the gut almost 2 fold?

Answer 21

Tregs

Question 22

Peripheral Tregs are reliant on what two factors?

Answer 22

Retinoic acid and TGFb

Question 23

TGFb is also necessary factor for what other immune component in the gut?

Answer 23

IgA (isotype switching)

Question 24

What autoimmune disorder is associated with Treg dysfunction?

Answer 24

IPEX (immune dysfunction, polyendocrinopathy, enteropathy, X linked)

Question 25

A mutation where leads to a loss of Tregs?

Answer 25

Foxp3

Question 26

Where are B cells activated in the gut?

Answer 26

GALT

Question 27

What’s the most abundant antibody in the human body?

Answer 27

IgA

Question 28

What is the GALT ration of B:T cells versus normal lymph nodes?

Answer 28

5:1

Question 29

What antibody is most abundant in the blood?

Answer 29

IgG

Question 30

IgA is able to get to the mucosal layer via transcytosis because of what?

Answer 30

Poly-Ig receptor (on IECs) It also gets cleaves and joins IgA afterwards to protect it a bit

Question 31

How to infants get IgA?

Answer 31

Breastfeeding

Question 32

Most common immunoglobulin deficiency that leads to decreased levels of IgA and normal IgM and IgG?

Answer 32

Selective IgA deficiency

Question 33

Clinical presentation of selective IgA deficiency?

Answer 33

Increases respiratory, gastrointestinal and GU infections + giardiasis risk (most asymptomatic)

Question 34

Short chain fatty acids produced by commensal gut bacteria have what role in immunity?

Answer 34

Stimulate Treg production + inhibit neutrophil activation

Question 35

When an immune response is elicited in the gut, what do IECs produce?

Answer 35

IL1, TNFa, IFNy

Question 36

What live attenuated vaccine is delivered orally to stimulate musical IgA response?

Answer 36

Polio live (Sabin)

Question 37

What is activated and where in an allergic food response that causes nausea, vomiting, diarrhea, and abdominal pain?

Answer 37

Mast cells in Lamina propria

Question 38

Why does an allergic food response also led to anaphylactic/systemic symptoms too?

Answer 38

Antigens activate mast cells in different tissues too

Question 39

What are the antibodies in a pernicious anemia directed against?

Answer 39

Intrinsic factor (via parietal cells of stomach needed for B12 absorption at intestine)

Question 40

What is the leading theory on what causes IBDx?

Answer 40

Inadequate Treg mediated suppression to commensal invasion — Th1 — Inflammation

Question 41

Crohn’s disease illicit what kind of reaction in the gut that is thought to cause defect in inflammasome mediated intracellular signaling to bacterial products?

Answer 41

Granulomatous reaction

Question 42

Can affect any part of GI tract, NOD2 loss of function mutation, and Th1 mediated (IFNy + IL12) granulomatous inflammation?

Answer 42

Crohn’s Dx

Question 43

Colon only, IL-10 suspectibility mutation, Th2 mediated (IL5)?

Answer 43

Ulcerative colitis

Question 44

What is triggering the immune responses in celiacs disease?

Answer 44

Deamidated gliadin (presented to DC and activate T cells that are intolerant)

Question 45

What CD4 T cells are implicated in celiacs?

Answer 45

HLA DQ2 HLA DQ8

Question 46

What antibodies are associated in celiacs?

Answer 46

Anti-tTG, antiendomysial, antigiladin

Question 47

What kind of antibodies should you look for if patient suspected with celiacs tests negative for IgA?

Answer 47

anti tTG-IgG

Question 48

Celiacs and Crohn’s are what kind of hypersensitivity reaction?

Answer 48

IV

Question 49

Chronic gastritis associated with H. Pylori infections can lead to what?

Answer 49

MALT lymphomas

Question 50

Painful swollen tongue, hyper segmented neutrophils in blood smear, macrocytic anemia, neurological symptoms, and hashimoto thyroiditis hint at a deficiency of what?

Answer 50

Intrinsic factor

Question 51

What will differentiate/hint a folate versus a B12 deficiency in a clinical stem?

Answer 51

Autoimmune disease (B12 autoantibody hint)