lecture 14- specialized immunity of the GI epithelial barriers

Question 1

after binding to its specific Antigen, a B cell may switch its______

Answer 1

immunoglobulin heavy chain class

Question 2

what do C3a and C5a cuase

Answer 2

vascular permeability

Question 3

describe the lamina propria

Answer 3

located under the epithelium. it is a loose connective tissue that contains blood and lymphatic vessels, and MALTs

Question 4

define GALTs

Answer 4

areas where immune cells congregate and some adaptive immune responses are initiated

Question 5

what do M cells do

Answer 5

deliver Ags across the epithelial barrier directly to sub epithelial DCs that then present Ag locally in adjacent mucosal T cell areas

Question 6

what do mucins do

Answer 6

prevent microbes from contacting epithelial cells

Question 7

describe the 2 layered gel that secreted mucins form

Answer 7

outer is a less dense layer that is normally colonized by bacteria. the inner is bacteria free. both layers contain anti-microbial substances that are produced by epithelial cells

Question 8

what is the apical surface of the GI epithelial cells coated with

Answer 8

glycocalyx

Question 9

define defensins

Answer 9

antimicrobial peptides contributing to the antimicrobial action of granulocytes, mucosal defense in the small intestine

Question 10

what produces defensins

Answer 10

epithelial and paneth cells

Question 11

what are the main defensins in the small bowel and what produces them

Answer 11

alpha-defensins produced by paneth cells

Question 12

what are the main defensins in the colon and what produces them

Answer 12

beta defensins produced by epithelial cells

Question 13

what are defects in defensins linked to

Answer 13

crohn’s disease

Question 14

what expresses PRRs

Answer 14

epithelial cells

Question 15

where is TLR5 expressed and what does it recognize

Answer 15

recognizes flagellins and is expressed on basolateral surface

Question 16

where are NOD-like receptors for flagellins expressed

Answer 16

in the cytosol of intestinal epithelial cells

Question 17

when will NOD-like receptors activate inflammatory responses

Answer 17

only when pathogenic bacteria or their products gain access to cytosol

Question 18

what is the dominant protective cell-mediated immune response in the cut consisting of

Answer 18

Th17 cells

Question 19

where is vitamin A converted to retinoid acid

Answer 19

peyer’s patch and mesenteric LNs

Question 20

what does retinoid acid induce

Answer 20

expression of CCR9 and integrin alpha4beta7

Question 21

why do effector lymphocytes enter circulation and home back to the gut lamina propria

Answer 21

because CCL25 and Madcam are displayed on lamina propria endothelial cells

Question 22

does TD or TI pathways stimulate high affinity IgA

Answer 22

TD

Question 23

how is IgA released into the lumen

Answer 23

proteolytic cleavage

Question 24

what is the lamina propria of the small bowel rich in

Answer 24

IL-17 producing Th17 cells

Question 25

what are IL-17 and IL-22 important for in the gut

Answer 25

induce the expression of mucins and beta-defensins, therefore protect the epithelial cells against microbial-induced injury

Question 26

what factors contribute to generation of Treg cells in the GI

Answer 26

Ag-activated DCs,
local production of RA,
local production of TGF-beta

Question 27

how are Treg cells thought to suppress immune responses in the gut

Answer 27

production of IL-10

Question 28

what are mutations in the IL-10 and IL-10R genes associated with

Answer 28

colitis

Question 29

defects in IL-2 and IL-2R are associated with what disease (in the gut)

Answer 29

inflammatory bowel disease

Question 30

what is the physiologic role of oral tolerance

Answer 30

prevent potentially harmful immune responses to food proteins and commensal bacteria

Question 31

when do commensal organisms become harmful instead of beneficial

Answer 31

when they cross the mucosal barrier

Question 32

what are the functions of commensals

Answer 32

degrade the components of our diet that our own cells cannot digest and to compete with potentially pathogenic microbes in the gut and prevent harmful infections

Question 33

commensal bacterial influence functions of circulating neutrophils and tissue macrophages by what bacterial products?

Answer 33

short-chain fatty acids (dampen neutrophil inflammatory responses),
peptidoglycan (enhances the killing of gram-positive bacteria),
microflora and its by-products (regulate systemic anti-viral functions of macrophages, DCs and NK cells)

Question 34

what is required for TD and TI B cell class switch to IgA

Answer 34

BAFF, APRIL, and RA

Question 35

what does IgA in the gut do

Answer 35

reduces innate responses to commensals and also limits B cell activation and Ab responses of other isotopes, both locally and systemically

Question 36

what is IBD likely due to

Answer 36

poorly regulated responses to commensal bacteria

Question 37

what are the 2 main types of IBD

Answer 37

crown’s disease and ulcerative colitis

Question 38

what is ulcerative colitis characterized by

Answer 38

patchy damage and restricted to the colonic mucosa

Question 39

what are symptoms of IBD

Answer 39

abdominal pain, vomiting, diarrhea, and weight loss

Question 40

define celiac disease

Answer 40

characterized by chronic inflammation in the small bowel mucosa

Question 41

what modifies gliadin

Answer 41

transglutaminase 2A

Question 42

what is the treatment for celiac disease

Answer 42

gluten free diets