Recent infant microbiome research Part 2:

The development of the infant microbiome, the development of the infant immune system and causal links to childhood leukaemia.

It can be tricky keeping up with the latest research on the infant microbiome. That’s why I’ve decided to collate some recent research and news articles into a series of blog-posts.

Here is a quick digest of recent research and news articles that caught my eye. It’s by no means a definitive list, but these are simply articles that I find interesting and help my understanding of the infant microbiome. I hope they will be helpful and interesting to you too.


DEVELOPMENT OF THE INFANT MICROBIOME

News article: What We Do and Don’t Know About Gut Health

BBC Future, 22nd Janaury 2019

Really good easy-to-read BBC article explaining about gut health including an explanation of the infant microbiome (the science explored in our Microbirth Movie and online courses) "Our microbiomes start developing when we're born, when microbes colonise the human gut.

Babies delivered by natural birth have been found to have higher gut bacterial counts than those delivered by Caesarean section because of the contact they make with their mother's vaginal and intestinal bacteria, says Lindsay Hall, microbiome research leader at Quadram Institute Bioscience.

"C-section-born infants miss out on that initial inoculation, and some of the microbes they come into contact with will be from the skin and environment" says Hall. "This is very important for infants to develop their immune systems. Recent work has suggested that disturbances in early life gut microbiome have negative consequences for host health," she says.


News article: New insights into the formation of the human airway microbiota

Unnamed author, Microbiome Post, 28th January 2019

Another piece of the puzzle on how vaginal birth/C-section and term/preterm birth affects the developing infant microbiome. New research finds that the lower airway microbiome forms in the first 2 months after birth, influenced by mode of birth and gestational age.

"In premature babies, delivery mode significantly contributed to explain the variation of airway microbiota composition. Ureaplasma, Streptococcus and Gemella were more abundant in samples from preterm babies born through vaginal birth than in samples from preterm babies born with C-section, which instead contained higher quantities of Propionibacterium and Planococcaceae. In children born at term, age rather than delivery contributed to explain the variation of airway microbiota composition. Prevotella, Veillonella, and Porphyromonas were more abundant in older children."


DEVELOPMENT OF THE INFANT IMMUNE SYSTEM

Review Article: Inherited nongenetic influences on the gut microbiome and immune system

Kathryn A Knoop et. al, Birth Defects Research, 21st December, 2018

Brilliant and relatively easy-to-understand paper summarising the importance of the transfer of microbes from mother to baby during birth, and how the infant gut microbiome and the infant immune system codevelop. I particularly love the conclusion - how parents give us more than our genes.

"The immune system and the gut microbiota develop jointly around the time of birth. Although both display some degree of plasticity, once established these “organ systems” are remarkably stable. There is a growing appreciation of the many influences that our parents, and particularly our mothers, have on the development of the gut microbiota and immune system through events occurring in utero and after birth. Our parents give us much more than genes."


Research paper: Healthy infants harbor intestinal bacteria that protect against food allergy

Taylor Feehley et al., Nature Medicine (2019), Published 14 January, 2019

Not a particularly easy read, but new research published in Nature journal shows that gut bacteria from healthy infants prevent food allergy in mice.

The abstract points to the hypothesis that the rise of food allergies is linked to misuse of antibiotics, diet, C-section and formula feeding which have altered the infant gut microbiome.

"There has been a striking generational increase in life-threatening food allergies in Westernized societies. One hypothesis to explain this rising prevalence is that twenty-first century lifestyle practices, including misuse of antibiotics, dietary changes, and higher rates of Caesarean birth and formula feeding have altered intestinal bacterial communities; early-life alterations may be particularly detrimental".


IMMUNE DEVELOPMENT AND CHILDHOOD LEUKAEMIA

News Article: Leading UK scientist reveals likely cause of childhood leukaemia

The Institute of Cancer Research, 21st May 2018

Here's a really good article exlaining about Professor Mel Greaves' 30 years research into acute lymphoblastic leukaemia (ALL) and how it links to the development of the infant microbiome and the priming of the immune system.

Professor Greaves suggests the likely cause of most cases of childhood leukaemia and how it may be preventable. "His studies of identical twins with ALL showed that two ‘hits’ or mutations were required.

The first arises in one twin in the womb but produces a population of pre-malignant cells that spread to the other twin via their shared blood supply. The second mutation arises after birth and is different in the two twins.

Population studies in people together with animal experiments suggest this second genetic ‘hit’ can be triggered by infection – probably by a range of common viruses and bacteria. In one unique cluster of cases investigated by Professor Greaves and colleagues in Milan, all cases were all infected with a flu virus.

Researchers also engineered mice with an active leukaemia-initiating gene, and found that when they moved them from an ultra-clean, germ-free environment to one that had common microbes, the mice developed ALL."


News article (on same research):For 30 years I’ve been obsessed by why children get leukaemia. Now we have an answer’

Robin McKie, The Guardian, 30th December, 2018

Fascinating article in The Guardian about the same research, on the link between childhood leukaemia and the development of the infant microbiome.

Cancer scientist Professor Mel Greaves finds that childhood leukaemia needs two 'hits' to get going - a genetic mutation in the womb combined with an infant immune system not being properly primed because the infant has not been exposed to the 'right' set of bacteria (the article suggests overuse of antimicrobial cleaners, from not breastfeeding and from an infant having fewer social contacts with other children).

If an infant with an unprimed immune system is then exposed to a common infection at a young age, the immune system can then over-react and trigger chronic inflammation. This can lead to the release of cytokines into the blood which in turn can trigger a second mutation in children carrying the first mutation, which can then lead to leukaemia.


Research paper (linked to news articles above): A causal mechanism for childhood acute lymphoblastic leukaemia

Mel Greaves, Nature Reviews Cancer 18, 471-484 (2018), Published 21st May 2018

Not an easy read, but a brilliant research paper!


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Infant Microbiome & Epigenetics