Lecture 12 : Intestinal inflammation and its microbiome

Question 1

General Introduction to the Intestinal Microbiome

Answer 1

The microbiome = a diverse, complex community of microbes in the gut.

Functions: digestion, vitamin production, immune modulation, protection from pathogens.

It’s dynamic – varies with age, diet, antibiotics, illness, etc.

Question 2

Structure and Function of the Intestinal Microbiome

Answer 2

Composition changes throughout life (e.g. birth, weaning, adulthood, ageing).

Major influencing factors: diet, antibiotics, host genetics, environment, disease.

Short Chain Fatty Acids (SCFAs) (e.g. acetate, propionate, butyrate):

• Produced by bacterial fermentation of fibre
• Support gut health, epithelial barrier, reduce inflammation

Question 3

Enterotypes

Answer 3

Enterotypes = microbiome “types” classified based on dominant bacteria.

3 main types (don’t need to memorise names of bacteria).

Not perfect – classification has limitations and overlaps.

Question 4

Intestinal Dysbiosis

Answer 4

Dysbiosis = imbalance in microbial composition (↓ diversity, ↑ harmful bacteria).

In IBD, dysbiosis = reduced beneficial bacteria (like SCFA-producers) and increased pro-inflammatory ones.

Loss of protective functions, altered immune response.

Question 5

Intestinal Dysbiosis & Disease

Answer 5

Dysbiosis contributes to C. difficile infections and other gastroenteritis.

Pathogens exploit disrupted microbiota → inflammation and disease.

CFU (Colony Forming Unit) data can identify likely pathogens (e.g. overgrowth of specific strains).

Question 6

Inflammatory Bowel Disease (IBD)

Answer 6

Chronic inflammation: Crohn’s Disease & Ulcerative Colitis.

Multifactorial: genetics, microbiota, immune dysfunction.

Treatments: anti-inflammatories, immunosuppressants, biologics, microbiome therapies.

Question 7

Microbiome Manipulating Therapies

Answer 7

Probiotic = live microbes (e.g. in yoghurt) that confer a health benefit.

Prebiotic = substance (e.g. fibre) that feeds beneficial bacteria.

FMT (Faecal Microbiota Transplantation): transplanting healthy stool to restore microbiome.

• Used for C. diff and being studied for IBD.
• Problems: standardisation, donor safety, unknowns about long-term effects.
• May work by restoring diversity, outcompeting pathogens, immune modulation.