Inflammatory Bowel Disease IBD

Question 1

Inflammatory Bowel Disease IBD

Answer 1

Covers two different diseases:
UC Ulcerative Colitis
Crohn’s Disease
-similar presentation but different underlying pathologies

Genetic and environmental factors

Question 2

IBD genetics

Answer 2

First degree relatives of IBD patients are 3-20x more likely to have IBD than general population
(but majority of people with IBD dont have fmaily hisotry)
Genetics may be more important in CD than UC
-higher concordance rates in monozygotic twins of CD than UC 50% vs 19%
Likely many genes involved and not fully elucidates
-NOD2 gene on chr16 mutations increase risk of CD in ileum (linked to chrons disease and ilitis) (terminal ileal disease)
Very uncommon in certain ethnic groups e.g. Maori, Pacific Island
But despite the role of genes, important to remember that majority of IBD patients (`85%) do not have a family history

Question 3

IBD environmental factors

Answer 3

1. Common in “western” industrialised nations
   -improved living standards- less exposure to enteric infections - less “tolerance” of immune system
   (genetic and/or living standards)
2. Smoking increases risk of Crohn’s disease
3. Smoking protective for UC
   -often develops within a year of stopping smoking
   -restarting smoking can lead to resolution of inflammation but: dont advise your patient to start smoking lol
   (doesnt seem to worsen disease)

Question 4

IBD pathophysiology

Answer 4

not fully understood
Disruption of the integrity and epithelial barrier (leading to abnormal immun response)
Dysregulation of both innate and adaptive immune system leading to abnormal immune responses and triggering of inflammation
-bacteria, foreign antigens that normally occur in LI/SI
Certain microbes in the gut may be pathogenic and initiate IBD

Question 5

Factors influencing IBD

Answer 5

1. Luminal microbial antigens and adjuvants
2. Immune response (abnormal immune response in gut to microbial and foreign antigens)
3. Environmental Triggers
4. Genetic susceptibility

Question 6

Ulcerative Colitis

Answer 6

Disease limited to colon (in name)
-Continuous: begins in rectum and spreads proximally (up colon) (extent of spread depends on patient’s severity of the condition)
-Mucosal inflammation: diffuse and granular (inflammation limited to mucosa only)
No macroscopic ulceration except in severe disease

Question 7

UC images

Answer 7

Rectum: generalised redness/rawness of mucosa

-less common/more severe UC: significant ulceration seen in Crohn’s , but can be seen in severe UC)

Question 8

Histology of UC

Answer 8

Mucosal inflammation only
-Chronic inflammatory infiltrate (plasma cells)
Crypt distortion (branching) and atrophy
-crypt normally shoudl be solitary, but has 2 branches coming off
Neutrophils invade crypts - “crypt abcess”
-cluster of neutrophils which have become lodged in crypt
Loss of goblet cells
Paneth cell metaplasia
-Paneth cells seen in areas in which they are not normally found (e.g. distal colon)

Question 9

Clinical UC

Answer 9

• can be similar to other colitis
  1. Diarrhoea with blood
• suggests inflammation
  2. Frequent bowel motions and urgency
• inflammed= diarrohea and frequency
  3. Abdominal discomfort
  4. Fever, malaise, weight loss (constitutional symptoms)

Question 10

Laboratory tests

Answer 10

1. Inflammation may result in:
   - Raised ESR/CRP, platelets, neutrophils
   - mild anaemia
   - raised ferritin
2. Bleeding, if prolonged, may result in:
   - iron deficiency- low ferritin/ with or without anaemi