18: The Microbiome And Human Disease

Question 1

What is meant by the term ‘dysbiosis’?

Answer 1

• is the balance in the microbial equilibrium
• it is a disturbance to gut microbiota homeostasis due to an imbalance in the flora itself, changes in their functional composition and metabolic activities or changes in their local distribution

Question 2

What is meant by the term ‘holobiont’?

Answer 2

A holobiont is an assemblage of a host and the many other species living in or around it, which together form a discrete ecological unit through symbiosis, though there is controversy over this discreteness

Question 3

Briefly discuss how short chain fatty acids modulate health and disease

Answer 3

• the interaction between the host and microbes depend on the stability of the epithelium
• microbes produce SCFA. What SCFA do is inhibit the NF-B pathway, this is a pro inflammatory pathway in immune cells
• by inhibiting this pathway the immune cells produce anti inflammatory cytokines that lower the stabilisation/maintenance of homeostasis of the epithelium layer

Question 4

Briefly discuss how it was demonstrated that the gut microbiota can induce obesity

Answer 4

• a study recruited twin humans (same genetic background). An obese twin and a lean twin. Mice were fed the faeces of the twins and it was then observed the mice raised with faeces of the obese twin were more fat mass than the mice raised with faeces of the lean twin

Question 5

Briefly discuss the role of gut microbiota in the development of a number of human diseases

Answer 5

• research suggests that bacterial populations in the gastrointestinal system play a role in developing gut conditions, including inflammatory bowel diseases such as crohns and ulcerative colitis. Low microbial diversity in the gut also has links to obesity and type 2 diabetes

Question 6

What is the difference between probiotics and prebiotics

Answer 6

Probiotics are live non pathogenic microorganisms that when ingested in adequate amounts exert a positive effect on the hosts health or physiology

Prebiotics is a selectively fermented ingredient that results in specific changes in the composition of the activity of the gut microbiota thus providing benefits upon host health