gastrointestinal mucosal immunology - basic science

Question 1

what are cytokines

Answer 1

chemical mediators that regulate cell immune responses

Question 2

what does the gastrointestinal tract represent

Answer 2

a major site of host-environment (luminal contents) interaction

Question 3

Gastrointestinal epithelial barrier

Answer 3

Single layer of cells – different phenotypes

Physical barrier between host and environment

Rapid restitution to retain continuity

Selective permeability of water, ions, nutrients

Question 4

Epithelial barrier growth dynamics

Answer 4

Lgr5+ stem cells in base of crypt

Proliferation and differentiation as move up the crypt

Cell shedding at tip

Autophagy important

Tight control by signalling molecules (epithelial cells/mesenchymal cells) – Wnt/B-catenin, Notch, BMP, Hedgehog

Question 5

Develop Self-tolerance

Answer 5

Non-responsiveness to self antigens

Question 6

Develop exogenous tolerance

Answer 6

Non-responsiveness to an enormous array of newly encountered environmental antigens (Food and Microbes)

Question 7

Develop an effective Immune response

Answer 7

Elimination or control of infections, allergic and noxious agents

Question 8

how do Gut dendrite cells and macrophages exist

Answer 8

exist as several phenotypes which have distinguishable cell markers and functions

Question 9

what is the role of DC subsets and macrophage

Answer 9

presenting antigen and driving T cell differentiation eg. Th1 or Tregs

Question 10

what is required fir the clearance of pathogens

Answer 10

Th1 cells and other proinflammatory cells eg Th17 cells are required

Question 11

what is required for maintaining immune homeostasis and tolerance

Answer 11

Tregs (Tregs, Tr1, Th3)

Question 12

what also contributes to mucosal tolerance

Answer 12

B cells through differentiation in plasma cells and IgA

Question 13

what does the epithelial barrier have

Answer 13

important structure and function as part of immune defence

Question 14

what is there a cross talk between

Answer 14

the epithelial barrier, microbiota and immune cells

Question 15

what are M cells

Answer 15

specialised and organised parts of the immune system in the gut

Question 16

what do cytokines do

Answer 16

they orchestrate and finely tune the immune response –pro-inflammatory and anti-inflammatory cytokines

Question 17

what 3 signals determines T cell response

Answer 17

MHC/peptide-TCR
CD80-CD28
Cytokine

Question 18

what are macrophages

Answer 18

phagocytic and ingest and kill foreign micro-organisms

Question 19

describe more on macrophages

Answer 19

first line of defence system in the gut

Tissue resident and monocyte derived

sampling of particulate antigens

phagocytic

secrete cytokines eg IL-10 required for the survival of FoxP3+ Treg cells

Professional APCs to modulate adaptive immune response

Question 20

describe IgA

Answer 20

• Binds to immune cells impacting their function eg phagocytosis, degranulation
• Antimicrobial
• Neutralises toxins
• Cross talk with microbiota tolerance

Question 21

cytokines are key

Answer 21

communication between cells and drive function