Inflammatory Bowel Disease

Question 1

What is inflammatory bowel disease?

Answer 1

Umbrella term for 2 idiopathic chronic inflammatory diseases:
Ulcerative colitis
Crohn’s disease

Question 2

What is indeterminate colitis?

Answer 2

Diagnosed when it is not clear if inflammation is due to Crohn’s or UC

Question 3

3 factors involved with pathogenesis of IBD?

Answer 3

Genetic predisposition
Problems with mucosal immune system
Environmental triggers

Question 4

3 facts about genetics of IBD, if a patient is diagnosed with it?

Answer 4

IBD risk in first degree relatives is increased

With monocygotic twins, the risk is higher in Crohn’s disease for the other twin, that in UC

Early onset may have strongest genetic links

Question 5

What is the best established risk factor for IBD development?

Answer 5

Positive family history

Question 6

What is an important mutation in Crohn’s patients?

Answer 6

NOD2 is a disease susceptibility gene, of which a mutated form is found in some Crohn’2 patients

Homozygotes have a higher risk of getting the disease than heterozygotes

Question 7

How does NOD2 contribute to development of Crohn’s?

Answer 7

Encodes a protein involved in bacterial recognition and, when mutated, this is lost

Question 8

2 reasons why gut flora is important in IBD?

Answer 8

Antibiotics are effective in treating perianal Crohn’s disease

There is an altered bacterial flora in the colon of patients with UC

Question 9

What is the normal immune system meant to do?

Answer 9

Tolerate dietary antigens and commensal flora

Question 10

4 components of the innate immune system in the GI tract?

Answer 10

Tight junctions regulate epithelial permeability

Hydrophobic mucus protects the epithelial cell layer

Defensins (cationic anti-microbial peptides) can be activated constitutively or in response to bacterial components

NOD2 contributes to normal mucosal defences

Question 11

Differences between mediation of Crohn’s and UC?

Answer 11

Crohn’s - Th1 mediated disease

UC - mixed Th1, Th2 mediated disease/natural killer T cells

Question 12

4 theories of IBD pathogenesis?

Answer 12

1. Pathogenic bacteria can produce toxins that cause bacterial resistance to killing by macrophages; the bacteria begin to invade the mucosa and an immune response is stimulated
2. Abnormal microbial composition
3. Defective host containment of commensal bacteria
4. Defective host immunoregulation alters tolerance there is altered antigen presentation function

Question 13

Changes in activity in Crohn’s and UC?

Answer 13

Anti-microbial activity in Crohn’s is reduced

There is too much bacterial killing in UC

Question 14

Smoking impact on Crohn’s and UC?

Answer 14

Aggravates Crohn’s disease

Protects against UC

Question 15

NSAIDs effect on IBD?

Answer 15

Aggravate

Question 16

What is UC?

Answer 16

Inflammation of the colon of unknown aetiology that has a relapsing course

Question 17

Compare and contract UC and Crohn’s disease?

Answer 17

ADD TABLE

Question 18

Determining the severity of UC?

Answer 18

> 6 bloody stools every 24 hours

AND

1 or more of:
Fever 
Tachycardia
Anaemia 
Elevated CRP

Question 19

Investigations for UC?

Answer 19

CRP and albumin (negative acute phase reactant - severe inflammation will decrease this)

Plain AXR, endoscopy and histopathology

Question 20

2 signs of UC on AXR?

Answer 20

Stool will be absent in an inflamed colon

Thumb-printing sign indicates mucosal oedema

Toxin megacolon if transverse colon is greater than 5.5 cm or caecum is greater than 9 cm

Question 21

What is a toxin megacolon?

Answer 21

Massive distension that can lead to perforation

Question 22

What to ask in a UC history?

Answer 22

Recent travel
Antibiotics
NSAID’s
Family history
Smoking
Skin, eyes, joints