immunology and infection of the gut:

Question 1

what is the microbiota in our gut?

Answer 1

• 10^4 resident bacteria. - Exposure to external pathogens - 4 major phyla: Bacteroidetes, Firmicutes, Actinobacteria and Proteobacteria.

Question 2

what are the main fucntions of the microbiota?

Answer 2

• Oral tolerance. - Enzyme alteration. - Motility alteration. - Alteration of cell turnover

Question 3

what is dysbiosis?

Answer 3

• altered microbiota composition

Question 4

what might dysbiosis be caused by?

Answer 4

• infection - diet - xenobiotics - hygiene - genetics

Question 5

what are the 3 areas to look at in mucosal defence?

Answer 5

• Physical defence - commensal bacteria - immunological

Question 6

what is the immunological defence of the mucosal defence?

Answer 6

MALT and GALT.

Question 7

where is MALT found?

Answer 7

oral cavity

Question 8

where is GALT present? what are the two main forms?

Answer 8

GALT is rich in BOWEL. organised : - Cryptopatches - Peyer’s patches – small intestine - Isolated lymphoid follicles – colon. - Mesenteric lymph nodes. non organised: just floating randomly in subepithelial: - Intra-epithelial lymphocytes. - Lamina propria lymphocytes.

Question 9

where are the peyers patches found?

Answer 9

• Found in the small intestine - Composed of B and T cell areas - Develops throughout life into teens

Question 10

what are features of peyers patches?

Answer 10

-No goblet cells. - No secretory IgA. - No microvilli. - Infiltrated by T/B-cells, macrophages and DCs

Question 11

how are antigens uptaken by the peyers patch?

Answer 11

• the m cells

Question 12

what do dendritic cells do?

Answer 12

Dendritic cells sample antigen using dendrites

Question 13

where do dendritic cells present the antigens?

Answer 13

• Naïve T-cells in Peyer’s patch. -Transport to mesenteric lymph nodes.

Question 14

what happens in the peyers patches?

Answer 14

• Mature naïve B-cells express IgM in PPs. - Upon activation, class switch to IgA. - They populate the lamina propria

Question 15

what secretes IgA ?

Answer 15

Up to 90% of the gut B-cells produce IgA

Question 16

what is T cell homing?

Answer 16

The homing system is regulated by: o The T-cell exhibits a4b7-Integrin. o The gut epithelium exhibits MAdCAM-1. The receptor interaction means the t-cell is specific to the gut.

Question 17

go over the cholera infectious diarrhea roataviruses noroviruses curved bacteria e coli Clostridium difficile

Answer 17

from the slides

Question 18

what is the mechanism of Coeliac disease ?

Answer 18

• gluten is not broken down in the stomach - when it reaches the small intestine it binds to the sig A and is transferred to the lamina propria

Question 19

what are symptoms of Coeliac disease?

Answer 19

Abdominal distension (bloating) Diarrhoea

Question 20

what is diagnosis and treatment of Coeliac disease?

Answer 20

Ab blood tests - anti-gliadin. Biopsy test of duodenum - manage diet

Question 21

what is the mechanism, symptoms and treatment of IBS?

Answer 21

• Visceral hypersensitivity - Recurrent abdominal pain Abnormal bowel motility Constipation and/or Diarrhoea - Diet modification - treatment of symptoms

Question 22

what are the phases of inflammatory bowel disease?

Answer 22

• pre disease - acute intestinal inflammation - becomes chronic - tissue destruction fibrosis or even cancer

Question 23

what are the initiating factors?

Answer 23

• genetic factors - environmental factors

Question 24

***** differences between crohns and ulcerative colitis?

Answer 24

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