External Influence of Early Childhood Establishment of Gut Microbiota and Subsequent Health Implications

Abstract

Postnatal maturation of immune regulation is largely driven by exposure to microbes. The gastrointestinal tract is the largest source of microbial exposure, as the human gut microbiome contains up to 1014 bacteria, which is 10 times the number of cells in the human body. Several studies in recent years have shown differences in the composition of the gut microbiota in children who are exposed to different conditions before, during, and early after birth. A number of maternal factors are responsible for the establishment and colonization of gut microbiota in infants, such as the conditions surrounding the prenatal period, time and mode of delivery, diet, mother’s age, BMI, smoking status, household milieu, socioeconomic status, breastfeeding and antibiotic use, as well as other environmental factors that have profound effects on the microbiota and on immunoregulation during early life. Early exposures impacting the intestinal microbiota are associated with the development of childhood diseases that may persist to adulthood such as asthma, allergic disorders (atopic dermatitis, rhinitis), chronic immune-mediated inflammatory diseases, type 1 diabetes, obesity, and eczema. This overview highlights some of the exposures during the pre- and postnatal time periods that are key in the colonization and development of the gastrointestinal microbiota of infants as well as some of the diseases or disorders that occur due to the pattern of initial gut colonization.

TRPV4-Mediated Detection of Hyposmotic Stress by Skin Keratinocytes Activates Developmental Immunity

“…In this regard, we and others have also reported the need of commensal microbes at birth/hatching to mediate a transient immune response and a delayed immune compensatory adaptation in part mediated by epigenetic changes (6,13). This early colonization by commensal microbes seems to have a crucial impact for the development of the immune system and the health status during adulthood (14)(15)(16). We show in this work that newly hatched germ-free (GF) zebrafish embryos sense the hyposmolarity of the aquatic environment to rapidly mount a protective innate immune response.…”

Gut microbiota and the development of pediatric diseases

“…Maternal impact on the gut microbiota of infants begins before delivery. Maternal factors such as antenatal infections, antibiotic use, smoking, and length of the gestation period (preterm or term) might affect colonization of the gut microbiota in infants [14].…”

“…Low gut microbiota diversity in early infancy is associated with increased risk of subsequent allergic diseases, such as asthma [27]. Repeated exposure to different bacterial antigens would enhance the development of immune regulation through inhibition of responses to inappropriate targets, such as gut contents and allergens [14].…”

The Effects of Diet and the Microbiome on Reproduction and Longevity: A Comparative Review Across 5 Continents

“…Thus, this suggests a mechanism, outside the maternal gut, by which the mother could be passing on her nutrition and health status to her child, albeit in the long-term. In relation to this, there is strong evidence for a link between early microbiota composition and later appearance of childhood disease [81]. But, as we have argued, the type of diet consumed and the composition of maternal microbiota seem somewhat unimportant in predicting immediate pregnancy outcomes.…”

“…For example, the negative impacts of antibiotic use on the microbiota are well known: an overall reduction in bacterial diversity, promotion of resistant species, and eradication of beneficial taxa, which creates room for pathogenic bacteria to grow, often occur [17]. Evidence suggests that in addition to short term damage, administration of antibiotics can have long-term consequences on the microbiota and overall health in both children [18] and adults [19]. Antibiotic use remains high, through people in developed countries having the financial resources, and those in developing countries often having access to cheap generic versions [20].…”