Emerging research: Epigenetics and the microbiome

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The following studies explore emerging and growing evidence that genetics, prenatal environments, delivery modes and early postnatal environments including feeding method can affect the infant microbiome, with significant implications for the infant immune system and both short and long term health outcomes. Find out more in our Breastfeeding and Relationship Building course

Association between breast milk bacterial communities and establishment and development of the infant gut microbiome

The establishment of the infant microbiome has lifelong implications on health and immunity, with gut microbiota of breastfed compared with non-breastfed individuals differ during infancy as well as into adulthood. Breastmilk contains a diverse population of bacteria, but little is known about the vertical transfer of bacteria from mother to infant by breastfeeding. In this 12-month longitudinal study of 107 healthy mother-infant pairs, researchers explored whether maternal breastmilk and areolar skin bacterial communities transferred to the infant gut. They found that breastfed infants received 27.7% of their gut bacteria from breast milk and 10.4% from areolar skin during the first month of life. They concluded that microbes in mother’s breastmilk seed the infant gut, including those associated with beneficial effects, underscoring the importance of breastfeeding in the maturation of the infant gut microbiome.

Pannaraj, P.S. et al (2017), Association Between Breast Milk Bacterial Communities and Establishment and Development of the Infant Gut Microbiome. JAMA Pediatrics, doi:10.1001/jamapediatrics.2017.0378

The microbiome in early life: implications for health outcomes

Recent studies have characterized how host genetics, prenatal environment and delivery mode can shape the newborn microbiome at birth. Following this, postnatal factors, such as antibiotic treatment, diet or environmental exposure, further modulate the development of the infant’s microbiome and immune system, and exposure to a variety of microbial organisms during early life has long been hypothesized to exert a protective effect in the newborn. Furthermore, epidemiological studies have shown that factors that alter bacterial communities in infants during childhood increase the risk for several diseases, highlighting the importance of understanding early-life microbiome composition. This review describes how prenatal and postnatal factors shape the development of both the microbiome and the immune system.

Tamburini, S, et al (2016). The microbiome in early life: implications for health outcomes, Nature Medicine, doi: 10.1038/nm.4142

Childbirth and consequent atopic disease: emerging evidence on epigenetic effects based on the hygiene and EPIIC hypotheses

This paper examines the emerging evidence that certain intrapartum and early neonatal interventions might affect the neonatal immune response in the longer term, and perhaps trans-generationally. It discusses the two leading theories in this area: the hygiene hypothesis, and the EPIIC hypothesis. The hygiene hypothesis proposes that in-utero, and in the first hours, weeks or months of life, the baby needs to gather a community of pre-existing microbes that come from the mother, as well as being exposed to bacteria from the surrounding environment, in order to protect against atopic and immunological diseases. The EPIIC hypothesis, in contrast, suggests that when labour and birth occur primarily without intervention (when the process proceeds physiologically) a healthy positive form of stress (eustress) is exerted on the fetus which programmes immune responses, genes responsible for weight regulation, and specific tumor-suppressor genes. The authors suggest drawing on both theories to help explain recent rises in the incidence of atopic and autoimmune disease.

Dahlen, HG, et al (2016). Childbirth and consequent atopic disease: emerging evidence on epigenetic effects based on the hygiene and EPIIC hypotheses, BMC Pregnancy and Childbirth, https://doi.org/10.1186/s12884-015-0768-9

The infant microbiome development: mom matters

In this evidence review, the authors argue that the infant microbiome plays an essential role in human health and its assembly is determined by maternal-offspring exchanges of microbiota. This process is affected by several practices, including Cesarean section (C-section), perinatal antibiotics, and formula feeding, which have been linked to increased risks of metabolic and immune diseases. The authors review recent knowledge about the impacts on infant microbiome assembly, discuss preventive and restorative strategies to ameliorate the effects of these impacts, and highlight where research is needed to advance this field and improve the health of future generations.

Mueller, NT, et al (2014), The infant microbiome development: mom matters, Trends in Molecular Medicine, DOI: https://doi.org/10.1016/j.molmed.2014.12.002

Cesarean Section and Chronic Immune Disorders

In this study, mature children born by cesarean delivery were analysed for risk of hospital contact for chronic immune diseases recorded in the Danish national registries in the 35-year period 1977–2012. Two million term children participated in the primary analysis. Researchers found that children delivered by cesarean delivery had significantly increased risk of asthma, systemic connective tissue disorders, juvenile arthritis, inflammatory bowel disease, immune deficiencies, and leukemia. No associations were found between cesarean delivery and type 1 diabetes, psoriasis, or celiac disease.

Sevelsted, A, et al (2014). Cesarean Section and Chronic Immune Disorders, Pediatrics, doi:10.1542/peds.2014-0596

Epigenetic effects of human breast milk

This paper suggests that although the different epigenetic mechanisms involved remain unclear, the benefits of breastfeeding against necrotising enterocolitis (NEC), infectious diseases, obesity and related-disorders, and cancer might be partly explained by the epigenetic model. By modulating gene expression without changing the nucleotide sequence of DNA, breast milk might positively modify the phenotype and the outcome even if there is a genetic predisposition for the development of diseases.

Verduci, E, et al (2014). Epigenetic Effects of Human Breast Milk, Nutrients, doi:  10.3390/nu6041711 

Natural Childbirth and Breastfeeding as Preventive Measures of Immune- Microbiome Dysbiosis and Misregulated Inflammation

This review argues that whilst technological advances in the management of pregnancy, childbirth and infant development have helped reduce the burden of some childhood illnesses, they have also undermined the microbial-rich experiences of natural childbirth and breastfeeding, producing serious, unanticipated consequences for today’s children: an increased likelihood for human-microbiome incompleteness, lifelong immune dysfunction, and inflammation-promoted chronic disease. This review will examine recent evidence suggesting that a more effective blending of ancient practices and remedies with modern technology and medical knowledge could help to restore the human-microbiome super organism to its historic status, improve pediatric immune homeostasis and reduce risk of later-life chronic diseases.

Dietert, RR (2013). Natural Childbirth and Breastfeeding as Preventive Measures of Immune-Microbiome Dysbiosis and Misregulated Inflammation. Journal of Infectious Diseases & Preventive Medicine, doi: 10.4172/2329-8731.1000103

An overview of epigenetics in nursing

Epigenetic changes to the genome are biochemical alterations to the DNA that do not change an individual’s genome but do change and influence gene expression. This article discusses current epigenetic nursing research, provides an overview of how epigenetic research relates to nursing practice, makes recommendations, and provides epigenetic online resources for nursing research. An overview of major epigenetic studies in nursing (specific to childbirth studies, preeclampsia, metabolic syndrome, immunotherapy cancer, and pain) is provided, with recommendations on next steps.

Clark, A, et al (2013). An overview of epigenetics in nursing, The Nursing Clinics of North America, doi: 10.1016/j.cnur.2013.08.004

The human milk microbiome changes over lactation and is shaped by maternal weight and mode of delivery

This study found that maternal weight and mode of delivery impacted the human milk microbiome. Milk from obese mothers tended to contain a different and less diverse bacterial community compared with milk from normal-weight mothers. Milk samples from elective but not from nonelective mothers who underwent cesarean delivery contained a different bacterial community than did milk samples from individuals giving birth by vaginal delivery, suggesting that it is not the operation per se but rather the absence of physiological stress or hormonal signals that could influence the microbial transmission process to milk. The findings emphasise the necessity to better understand the role that the microbiome could play for human health.

Cabrera-Rubio, R, et al (2012). The human milk microbiome changes over lactation and is shaped by maternal weight and mode of delivery, American Journal of Clinical Nutrition, doi: 10.3945/ajcn.112.037382

Epigenetic changes in early life and future risk of obesity

This study reviews evidence for the impact of fetal and early postnatal environments on the risk of developing obesity in later life, with a focus on how particular environments can alter epigenetic regulation of specific genes. The researchers suggest that understanding the role of epigenetics in risk of obesity opens the possibility of new interventions to modify long-term obesity risk and combat the rapid rise in obesity that has been occurring over the last two decades.

Lillycrop, KA, and Burdge, GC (2011). Epigenetic changes in early life and future risk of obesity, International Journal of Obesity, DOI: 10.1038/ijo.2010.122