L4: Human Microbiome II Flashcards
factors influencing the gut microbiome - in utero
- antibiotic use by the mother
- mother’s diet
factors influencing the gut microbiome - parturition
- hospital setting
- length of gestation
- mode of delivery (c-section vs vaginal)
factors influencing the gut microbiome - infancy
- environment
- prebiotics/probiotics
- formula feeding vs breastmilk
- introduction of solid food
explain the evolving microbiome from pregnancy to early infancy - childhood
- diverse
- no dominant species
explain the evolving microbiome from pregnancy to early infancy - reproductive age
- microbiome composition changes
- Lactobacillus is selected for
explain the evolving microbiome from pregnancy to early infancy - menopause
- diversity goes down
- Ureaplasma is selected for
how does the vaginal microbiome change?
- it changes with the menstrual cycle
- bacterial abundance peaks during ovulation bc of estrogen levels rising
- which microbe increases is different for each individual
what species dominates the vaginal microbiome in women of reproductive age?
Lactobacillus because it keeps pH low
vaginal microbiome in women of reproductive age - what about women who do not have a domination of Lactobacillus spp.
- they instead have a much more diverse microbiome
- they instead have more anaerobic bacteria
- a case for many women of color
vaginal microbiome in women of reproductive age: more anaerobic bacteria - how is the pH kept low
the anaerobic bacteria can produce lactic acid that will keep the pH low
what is a nugent score
a way of evaluating vaginal microbiota for bacterial vaginosis
what is bacterial vaginosis (BV)
- characterized by a shift in the composition of the normal vaginal microbiome
- microbiome changes from Lactobacillus species to a mixture of anaerobic and facultative anaerobic bacteria
- known as the microbiome of disease
why is BV dangerous
- it is not effective at keeping pH low
- causes a high risk of pre-term birth
BV vs normal microbiome - what does a Lactobacillus-dominated microbiome produce
- lactic acid
- bacteriocins
- hydrogen peroxide
- all keep the pH low
BV vs normal microbiome - what does a BV microbiome produce
- SCFAs and pH will be increased
- pro-inflammation
BV vs normal microbiome - is BV truly a microbiome of disease
- no
- some people naturally have more anaerobic bacteria and they may not show symptoms of BV
- they are just more likely to have colonialism of opportunistic bacteria
how is the human vaginal microbiome unique
humans have 70% Lactobacillus spp. while other mammals only have 1%
how is the human vaginal microbiome unique - what is the proposed reason for this
vaginal pH of humans evolved to be low to make associations with Lactobacillus spp. since they resided in the gut
the microbiome in early life - birth
- vaginal delivery: Lactobacillus was received from the mom
- c-section: Staphylococcus, Propionibacterium. Not from mom but from the environment
the microbiome in early life - infant
- milk consumption: Bifidobacterium, Lactobacillus
- solid food introduction: Bacteroides, Clostridiales
the microbiome in early life - toddler
- full adult diet
- can still find early microbiome association prevalent
what is the impact of delivery mode on the infant
c-section babies are more prone to develop allergies, chronic inflammatory diseases, and metabolic disease
impact of delivery mode on the infant microbiome - c-section
- horizontal gene transfer
- specifically Staphylococcus and Propionibacterium
what is the impact of delivery mode on the infant - vaginal
- vertical transmission
- Lactobacillus
how may RSV be prevented in infants
- breastfeeding
- human milk oligosaccharides (hMOSs) reduces the viral load and inflammatory signaling
- it travels to the blood and lungs
what is respiratory synoptical virus (RSV)
leading cause of lower respiratory infections which is a major source of infant mortality
factors influencing microbiome composition - baby
- formula-fed: Firmicutes is dominant
- breastfed: Actinobacteria is dominant
- solid-food: Bacteroidetes
factors influencing microbiome composition - toddler
- healthy: Bacteroidetes
- antibiotic treatment: too much Bacteroidetes and too little Firmicutes
- malnutrition: Proteobacteria
factors influencing microbiome composition - adult - elderly
Firmicutes
how does the gut microbiome change in mother and child
- early microbiome: child resembles mother
- gets less similar as child gets older
how does the oral microbiome change in mother and child
changes between mother and child are visible after 6 months
what are the habitat for the oral microbiome
- supragingival plaque (teeth and gums)
- buccal mucosa (inner cheek)
- tongue dorsum (upper surface of the tongue)
oral microbiome - what is the most common microbe
- biofilms in teeth and gums
- buccal mucose: Strptococcus spp. is dominant
- tongue: more diverse sets of microbes
explain the microbial colonization of freshly cleaned teeth
- Streptococcus and Actinomyces
- Streptococcus and Actinomyces attract more proteins
- Veillonella
- Porphyromonas
- Fusobacterium
- Treponema and yeast Candida
microbial colonization of freshly cleaned teeth - Streptococcus and Actinomyces
- they are early colonizers
- attracted to statherin in saliva
- will colonize again after brushing your teeth
microbial colonization of freshly cleaned teeth - Streptococcus and Actinomyces attract more proteins
- amylase, lactoferrin, and other proteins
- to assist with colonization
- these then form thick biofilms
microbial colonization of freshly cleaned teeth - Veillonella
- Veillonella and other bacteria colonize the teeth
- Veillonella is attracted to Actinomyces
microbial colonization of freshly cleaned teeth - Porphyromonas
- anaerobic bacteria Porphyromonas colonize the teeth
- its attracted to the anaerobic conditions
- biofilm becomes thicker and makes it hard to get rid of
microbial colonization of freshly cleaned teeth - Fusobacterium
anaerobic microenviornemtns allow the interaction of Porphyromonas with Veillonella followed by the adherence of another anaerobe Fusobacterium
microbial colonization of freshly cleaned teeth - Treponema and yeast Candida
colonization by Treponema and yeast Candida
plaque growth rate and inflammation response - unbrushed teeth
plaque had some growth rate but different inflammation rate
plaque growth rate and inflammation response: brushed teeth - cytokines vs other bacteria
- cytokines: low inflammation expressed
- other bacteria: started a inflammation response as soon as the biofilm began to form
plaque growth rate and inflammation response - brushed teeth
bacteria accumulation is steady overtime
plaque growth rate and inflammation response - is it the same for every individual?
- no
- people with the same microbiome will have different responses and rates
what are dental caries
- dense biofilm formation in a specific part of the teeth
- categorized by the abundance of:
1. biofilm-forming bacteria
2. acid-producing and acid-tolerant bacteria
dental caries - what embodies all 3?
Streptococcus mutants
what is periodontal disease
- an inflammatory disruption in the host-microbial homeostasis of the periodontal pocket
- results in biofilm colonizing inside the gums and the bacteria will start to secrete molecules that degrade teeth
- categorized by microbial dybiosis
periodontal disease - microbial dybiosis
- a decrease in the abundance of Proteobacteria and Acinobacteria
- increase in the abundance of Bacteroidetes and Firmicutes
periodontal disease - what bacteria are constantly enriched
- Porphyromonas gingivalis
- Fusobacterium nucleatum
periodontal disease and various pathologies
- positive correlation
- lesions in gums can cause bacteria to travel to the gut and through the blood stream
- this can then cause an inflammatory response where molecules produced by bacteria travel and activate inflammation in the gut
periodontal disease and variaous pathologies - example
- Alzheimer’s disease
- correlated with gum disease
skin microbiome - explain the skin
- human body’s largest organ
- serves as a physical barrier
- heavily colonized by diverse microorganisms that sit on the surface of the skin (epidermis) but also reside deep in hair and glands
skin microbiome - what factors influence skin microbiome diversity
- host physiology
- environment
- immune system
- host genotype
- lifestyle
- pathobiology
skin microbiome: what factors influence skin microbiome diversity - host physiology
- sex
- age
- site on skin
skin microbiome: what factors influence skin microbiome diversity - environment
- climate
- geographical location
skin microbiome: what factors influence skin microbiome diversity - immune system
- previous exposures
- inflammation
skin microbiome: what factors influence skin microbiome diversity - host genotype
- susceptibility genes
- such as filaggin
what factors influence skin microbiome diversity: host genotype - what is filaggin
- a protein in the epidermis
- it is related to how much keratin is deposited in the skin
- this relates to how thick the epidermis is
skin microbiome: what factors influence skin microbiome diversity - lifestyle
- occupation
- hygiene
skin microbiome: what factors influence skin microbiome diversity - pathobiology
- underlying conditions
- such as diabetes
skin microbiome vs other areas
- skin: more diverse and more spread out in a phylogenetic tree
- other areas: less diverse and more close to each other in a phylogenetic tree
skin microbiome - what species is dominant in sebaceous areas
Propionibacterium spp.
skin microbiome - what species is dominant in moist areas
Staphylococcus and Corynebacterium spp.
skin microbiome - what species is dominant in dry areas
- a mixed representation from phylum Actinobacteria, Proteobacteria, Firmicutes, and Bacteroidetes
skin disorders associated with the microbiome
- acne
- atopic dermatitis (AD)
- rosacea
skin disorders - acne
involves androgen-induced increases in:
- sebum production
- altered keratinization
- inflammation
- dysbiosis of facial skin
skin disorders: acne - what are the 2 major microbes associated with acne
- Staphylococcus epidermidis and Cutibacterium acnes
- contribute to acne by penetrating follicles and creates an inflammatory response
- but is also known to promote health
skin disorders: acne - how do Staphylococcus epidermidis and Cutibacterium acnes promote health
by inhibiting growth and invasion of pathogens
skin disorders - atopic dermatitis (AD)
- dysfunction of the skin barrier caused by mutation in the gene that encodes for filaggrin
- a protein involved in cornification
skin disorders: AD - what microbes are dominant
- increased bacterial colonization of Staphylococcus aurenus and viral infections
skin disorders: AD - that are the 2 stages
- non-flare: microbiome if still different but has less Staphylococcus aurenus
- flare: noticeable increase in Staphylococcus aurenus colonization
skin disorders - rosacea
- disregulstion of the immune system
- imbalance of in microbial composition
- but Demodex mite has been found on healthy skin is significantly increased which activates the inflammation response
