Impacts of Different Perinatal Factors on Faecal Immune Compounds in Infants: Determination of Normal Values.

The gut microbiota is a key and primary stimulus for the development of a host's immune system. The early establishment of the gut microbiota is affected by several perinatal factors but little is known about their influence on shaping normal immune development and, consequently, on the programming of future health. The analysis of different immune compounds is well-documented in serum samples; however, their presence in faecal samples has not been studied, and this information could be valuable in early life. In this context, the authors of this study aimed to both describe the immunological faecal profile of a cohort of one-month-old infants and describe the impact of different perinatal factors, exploring possible associations between immune compounds and gut microbiota in faecal samples. Clear differences in immune profile were observed between full-term and premature infants. Breastfeeding increases IgG2, IgG4, and IgA; in addition, male babies showed some increased Igs, among other observations. Overall, the findings of this study reinforce the hypothesis that microorganisms and immune compounds interact with each other in the early neonatal gut and that understanding these interactions in depth will help us comprehend the influence of the gut microbiota on short- and long-term infant health outcomes.