Development of the gut microbiota in infancy & its impact on health in later life Flashcards
Define gut microbiota
Microorganisms incl. bacteria, archaea & fungi that live in the digestive tracts.
What is the hygiene hypothesis?
States that less expose to parasites + microbes leads to an overreactive immune system.
When is gut microbial ecology + function dynamic and when is it stabilised?
Dynamic in infancy
Stabilised in childhood
Functions of a healthy gut microbiota
Metabolising barely digestible polysaccharides
Detoxification
Barries vs pathogens
Aiding in development of the host immune system
Define dysbiosis
When the symbiotic relationship between the host + gut microbiota is altered.
What diseases is dysbiosis associated with?
IBD
IBS
Obesity
Allergy
Brain disorders
When does intestinal bacterial colonisation begin?
When a foetus is in the lower uterus.
When are infants gut microbiota established?
After birth, after 2 big transitions in infancy.
Infants gut microbiota is established after birth after 2 big transitions in infancy, what are these?
Lactation
Weaning period
Infants gut microbiota is established after birth after 2 big transitions in infancy.
What does lactation result in for the gut microbiota?
The dominance of bifidobacterium
Infants gut microbiota is established after birth after 2 big transitions in infancy.
What does the weaning period result in for the gut microbiota?
Establishment of an adult-type complex microbiome dominated by bacteriodetes + firmicutes.
Up to what age do the 2 big transitions causing a change to infants gut microbiota continue until?
3 years of age
Define enterotypes
Classification of org. based on the bacteriological composition of their gut microbiota.
What are enterotypes classified into?
3 types dominated by:
- Bacteroides
- Prevotella
- Firmicutes
What is the early establishment of gut microbiota affected by?
Delivery mode (cesarean vs vaginal delivery)
Breast milk vs formula feeding
Antibiotic use
Timing of intro of solid foods + cessation of milk feeding
Intestinal bacteria + their metabolites incl short chain FAs play an important role in the proliferation + differentiation of T cells such as…
Regulatory T cells
Helper T cells
B cells
What can disturbances to the development of gut microbiota in infancy cause?
Immune diseases
i.e food allergies, atopic dermatitis (eczema) + asthma.
What is an infants gut microbiota dominated by + maintained until the introduction of solid food?
Bifidobacterium (“Bidifus flora”) + some lactic acid bacteria.
What happens to an infants gut microbiota after weaning?
Bidifus flora is outcompeted by adult-type organisms i.e
Bacteroides
Prevotella
Ruminococcus
Clostridium
- These colonise the infants intestines.
What do solid foods do to gut microbiota?
Promote the growth of bacteria enriched in gene coding to allow the utilisation of a larger variety of CHO + vitamin synthesis.
EFFECT OF THE MODE OF NEWBORN DELIVERY
Vaginally delivered
Their gut microbiota resemble that of the mothers vagina.
What is the mothers vaginal microbiota dominated by?
Lactobacillus
Prevotella
Sneathia
EFFECT OF THE MODE OF NEWBORN DELIVERY
Caesarean delivery
Newborns gut microbiota are most similar to skin microbiota
What is skin microbiota dominated by?
Staphylococcus
Corynebacterium
Propionibacterium
What happens to newborns born through elective caesarean (planned caesarean)?
Have low bacterial diversity
What has caesarean birth been associated w?
⬆️ risk for immune disorders i.e asthma + celiac disease.
What does human milk contain?
Proteins
Fats
CHO
Immunoglobulins
Endocannabinoids
What are immunoglobulins?
a.k.a antibodies
Glycoprotein mol prod by plasma cells (WBCs).
Act as a critical part of the immune response by specifically recognising + binding to particular antigens i.e bacteria or viruses + aiding in their destruction.
What are endocannabinoids?
Endogenous ligands of cannabinoid receptors.
What does the use of antibiotics in infants do to gut microbiota?
Shifts its composition towards a high abundance of proteobacteria + low abundance of actinobacteria populations.
⬇️ overall diversity of microbiota
Selects for drug-resistant bacteria
What is childhood microbiota affected by?
Geography + food culture
What is the gut microbiota of children in advanced countries dominated by?
Bacteroides
Firmicutes
What is the gut microbiota of children in developing countries dominated by?
Prevotella
