To date, no effective strategy has been identified for reliably preventing the development of eczema and allergy in children at high risk of these conditions. Eczema (atopic dermatitis) is typically one of the first allergic manifestations to appear in infants predisposed to allergic disease. Thus, the condition is of particular interest when it comes to prevention.
Since early life gut microbiota development occurs at a time when key cognitive, metabolic, and immune functions are maturing, some scientists have begun to investigate whether the gut microbiota could be a potential way to predict, from among the population at risk, which children will go on to develop eczema and other allergic diseases.
A new study by a group of scientists from Danone Nutricia Research (the Netherlands), the Laboratory of Microbiology at Wageningen University (the Netherlands), and the Department of Medicine at Imperial College London (United Kingdom) explored how the gut microbiota tracks eczema development in early life—and also whether gut microbiota composition was modulated by a prebiotic early-life dietary intervention.
Researchers analyzed the fecal samples of 138 vaginally-born infants at increased risk of allergy (that is, with a parental history of allergic disease); the samples were collected from each infant at 4 and 26 weeks. Stool measurements of pH and lactate, as well as short-chain fatty acids, were also taken at 4, 12, and 26 weeks. The babies who (for various reasons) were not breast-fed consumed either standard cow’s milk formula (n=57) or a partially hydrolyzed formula containing specific oligosaccharides (pHF-OS) (n=51). These groups were compared with a reference group of breast-fed infants (n=30).
By 18 months, 52 of the 138 infants (about 38%) showed symptoms of eczema. The infants who went on to develop eczema by 18 months showed compositional differences in their gut microbiota compared to those not developing eczema: at 4 weeks, they showed decreased relative abundances of Parabacteroides and Enterobacteriaceae, while at 26 weeks they showed decreases in Eubacterium and Anaerostipes species, which are known to use lactate and to produce butyrate. So unsurprisingly, increased lactate and decreased butyrate were also observed at the 26-week mark in the stool of infants who would later develop eczema.
Previously, a ‘parent’ study, called the “PATCH trial“, had showed immunological changes in infants receiving the pHF-OS intervention, but no reduced incidence of eczema at 12 or 18 months. In the current study, the researchers followed up with the question of whether this early-life nutritional intervention modulated the gut microbiota composition in a potentially beneficial way.
Researchers assessed the similarity in microbiota composition between groups using a measure of phylogenetic distances and relative abundances of bacterial taxa in pairwise comparisons of samples. At 26 weeks, the infants receiving pHF-OS were more similar in composition to those in the breast-fed group than were the infants receiving control formula. Compared to the control formula group, the pHF-OS group showed increased levels of Bifidobacterium species, with decreased levels of Clostridium species as well as an unassigned genus of Lachnospiraceae. Overall, the authors found, fecal microbiota composition, metabolites, and pH in infants who received the prebiotic-supplemented formula rather than the standard formula were closer to those of breast-fed infants. This trajectory may indicate a benefit, as previous evidence suggests exclusively breast-fed infants have a lower risk for childhood eczema.
This study shows gut microbiota composition in the first six months of life deserves more exploration as a way to predict the development of eczema; furthermore, it shows the potential of a prebiotic-enriched formula to modulate the gut microbiota in a manner that may be beneficial. No specific microbial biomarkers of eczema were identified, however, and further prospective studies are warranted.
Wopereis H, Sim K, Shaw A, Warner JO, Knol J, Kroll S. Intestinal microbiota in infants at high risk for allergy: Effects of prebiotics and role in eczema development. J Allergy Clin Immunol. 2017. doi: 10.1016/j.jaci.2017.05.054