The existence of a neonatal window was first highlighted by epidemiological studies that revealed the particular importance of this early time in life for the susceptibility to immune-mediated diseases in humans. Recently, the first animal studies emerged that present examples of early-life exposure–triggered persisting immune events, allowing a detailed analysis of the factors that define this particular time period. The enteric microbiota and the innate and adaptive immune system represent prime candidates that impact on the pathogenesis of immune-mediated diseases and are known to reach a lasting homeostatic equilibrium following a dynamic priming period after birth. In this review, we outline the postnatal establishment of the microbiota and maturation of the innate and adaptive immune system and discuss examples of early-life exposure–triggered immune-mediated diseases that start to shed light on the critical importance of the early postnatal period for life-long immune homeostasis.
This work was supported by the Deutsche Forschungsgemeinschaft (Ho2236/8-1, Priority Program 1656, and Priority Program 1580 [to M.W.H.] and TO 1052/1-1 [to N.T.]).
Abbreviations used in this article:
- dendritic cell
- inflammatory bowel disease
- invariant NKT
- peripheral-induced Treg
- regulatory T cell
- thymus-derived regulatory T cell.
- Received July 19, 2016.
- Accepted October 17, 2016.
- Copyright © 2017 by The American Association of Immunologists, Inc.