Microbiota

Question 1

antimicrobial peptides in mucosa

Answer 1

defensins and cationic proteins

Question 2

competitors in mucosa

Answer 2

lactoferrin and vitamin B12-binding protein

Question 3

what cells are the primary producers of antimicrobial peptides in the small intestine?

Answer 3

Paneth cells

Question 4

name 4 major antimicrobial peptides (AMPs) made by Paneth cells

Answer 4

defensins, lysozyme, phospholipase A2, reg3gamma

Question 5

what are defensins?

Answer 5

cationic antimicrobial peptides made by Paneth cells; kill microbes by forming pores in their cell membrane

Question 6

compare functions of lysozyme and phospholipase A2

Answer 6

lysozyme hydrolyzes proteoglycan in gram positive bacterial cell wall, whereas phospholipase A2 hydrolyzes fatty acids in bacterial cell membrane (preferred activity against gram positive)

Question 7

function of reg3gamma

Answer 7

C-type lectin made by Paneth cells, binds to peptidoglycan, bactericidal against gram-positive, inducibly expressed upon TLR activation by bacteria or PAMPs

Question 8

what antibody compensates when there is IgA deficiency?

Answer 8

IgM

Question 9

serum IgA is predominantly ____meric while mucosal IgA is predominantly ____meric

Answer 9

mono, poly

Question 10

a patient has meningitis (H. influenzae, N. meningitidis, S. pneumoniae). what is the likely mechanism that the bacteria evaded IgA?

Answer 10

specific IgA proteases

Question 11

name 4 mechanisms that microbes use to evade IgA

Answer 11

specific IgA proteases, other proteases, glycosidases, IgA binding proteins

Question 12

define symbionts

Answer 12

share mutual relationship with the host, have known health promoting functions (don’t cause disease)

Question 13

define commensals

Answer 13

permanent residents of the ecosystem that provide no benefit or detriment to the host

Question 14

define pathobionts

Answer 14

live as commensals but have the potential to induce pathology, also called opportunistic pathogens

Question 15

where do short chain fatty acids come from?

Answer 15

commensal bacteria ferment nondigestable polysaccharides

Question 16

what do short chain fatty acids regulate? (4)

Answer 16

1. immune cells (PMNs, DCs, macrophages/monocytes)
2. intestinal epithelial cells
3. regulatory T cell differentiation
4. expression of virulence factors on bacterial pathogens

Question 17

define IBD

Answer 17

abnormal immune response to colonizing bacteria in a genetically susceptible host

Question 18

the characteristic shift in microbial colonization in IBD moves from ________ bacteria to _________ species, predominantly _________, most likely associated with __________.

Answer 18

obligate anaerobic; facultative anaerobic; proteobacteria; increased oxygen tension caused by inflammation

Question 19

probiotics skew T cell immune responses to _____ type

Answer 19

Th1