Lecture C6 - Human Mycobiome in Health and Disease

Question 2

What is the human mycobiota?

Answer 2

50 genera of fungi found on or in the skin that are recognised as a necessary component of our physiology.

Question 3

Describe the human mycobiota.

Answer 3

Mucosal surfaces have a more diverse range than the skin.
Colonise infants early in life through the mother just like microbial species.
Diet - high fibre/high animal products.
Links in this contributing to multiple disease states and maintaining homeostasis.

Question 4

What is the most common mycobiota found on the skin?

Answer 4

Malassezia.

Question 5

What is the most common mycobiota in the colon and vagina?

Answer 5

Canidia.

Question 6

Describe primocolonisation in infancy.

Answer 6

Breastfeeding - colonisation with Malassezia, Candida and Saccharomyces.

Question 7

Describe

Question 8

What is the human mycobiota?

Answer 8

50 genera of fungi found in or on the human body that is recognised as a necessary component of our physiology.

Question 9

Describe the human mycobiota.

Answer 9

Mucosal surfaces are more diverse than on the skin.
The lung has environmental fungi.
Human infants are colonised very early on through the mother, just like bacterial species.
Links in this contributing to multiple disease states and maintaining homeostasis.

Question 10

What is the most common species grown on the skin?

Answer 10

Malasseiza

Question 11

What is the most common species in the colon and vagina?

Answer 11

Candida

Question 12

Describe primocolonisation of fungi in infancy.

Answer 12

Breastfeeding - colonisation with Malassezia, Candida and Saccharomyces.
Weaning and solid foods - decrease in diversity, D. hansenii high abundance gradually replaced by S. cerevisiae.

Question 13

Describe the effect of vegetarian diet on the mycobiota.

Answer 13

Decreased viable fungi compared with animal-based diet.
Increased Candida.

Question 14

Describe the effect of a protein-rich diet on the mycobiota.

Answer 14

Decreased Debaryomyces and Candida. Increased Penicillium.

Question 15

Describe the effect of a Western diet on the mycobiota.

Answer 15

Decreased Alternaria, Saccharomyces, Septoriella and Tilletiopsis.

Question 16

Describe the mycobiota during adolescence and adulthood.

Answer 16

70% Ascomycota and 30% Basidiomycota.
Possible core fungal microbiota of ten genera.
Faecal-culturable fungi resistant to low pH, bile acids and oxidative stress.

Question 17

Why is the database for fungal genomes less than bacterial genomes?

Answer 17

They are harder to grow and lyse due to having a more complex, harder cell wall so it is harder to extract the DNA.

Question 18

What % of the sequences in the human microbiome project were of fungal origin?

Answer 18

0.01%

Question 19

What does the overgrowth of candida result in and what is it due too?

Answer 19

Oral and vagina thrush.
Infection in the gut.
Due to antibiotic use and the bacteria is eliminated that competes with candida, allowing it to overgrow.

Question 20

What disease allows for candida to grow in the lung?

Answer 20

Cystic fibrosis - causes severe physiological changes in the lung accompanied by the outgrowth of opportunistic pathogens. Candida can adapt to escape Pseudomonas aeruginosa mediated inhibition of the yeast to hypha transition.

Question 21

What factors can lead to increased growth of Candida in the vagina?

Answer 21

Glycogen and oestrogen produced during pregnancy.
HIV-mediated immunodeficiency and depletion of lactobacilli.

Question 22

How are fungi detected by the innate immune system?

Answer 22

Fungi mainly detected by the innate immune system.
Receptors usually recognised things in the fungal cell wall.

Question 23

In Crohn’s disease what is there fewer and more species of?

Answer 23

Fewer species of fusarium
More species of malassezia and cladosporium.

Question 24

What has been identified as a risk factor for Crohn’s disease?

Answer 24

A SNP in CARD9.
CARD9 signalling linked to many things but specifically to innate immune receptors for fungi.
Increased colonisation by malassezia is linked to a number of CARD9 S12A alleles.

Question 25

What are a diagnostic signature of Crohn’s disease?

Answer 25

ASCA - anti-saccharomyces cerevisiae antibodies.
Patients with high ASCA sera are more reactive against M. restricts than low ASCA sera.

Question 26

Does Malassezia directly cause worsening or is it through modulating the presence of another microbe?

Answer 26

M. restricts is sufficient to exacerbate colitis.
ASF mice - same results as the SPF mice and no significant difference in any bacterial species so likely DIRECT influence of malassezia.

Question 27

What produces a higher inflammatory immune response?

Answer 27

Malassezia