Intestinal goblet cells sample and deliver lumenal antigens by regulated endocytic uptake and transcytosis

Intestinal goblet cells maintain the protective epithelial barrier through mucus secretion and yet sample lumenal substances for immune processing through formation of goblet cell associated antigen passages (GAPs). The cellular biology of GAPs and how these divergent processes are balanced and regulated by goblet cells remains unknown. Using high-resolution light and electron microscopy, we found that in mice, GAPs were formed by an acetylcholine (ACh)-dependent endocytic event remarkable for delivery of fluid-phase cargo retrograde into the trans-golgi network and across the cell by transcytosis - in addition to the expected transport of fluid-phase cargo by endosomes to multi-vesicular bodies and lysosomes. While ACh also induced goblet cells to secrete mucins, ACh-induced GAP formation and mucin secretion were functionally independent and mediated by different receptors and signaling pathways, enabling goblet cells to differentially regulate these processes to accommodate the dynamically changing demands of the mucosal environment for barrier maintenance and sampling of lumenal substances

Synchronization of mothers and offspring promotes tolerance and limits allergy

Allergic disorders, characterized by Th2 immune responses to environmental substances, are increasingly common in children in Western societies. Multiple studies indicate that breastfeeding, early complementary introduction of food allergens, and antibiotic avoidance in the first year of life reduces allergic outcomes in at-risk children. Why the benefit of these practices is restricted to early life is largely unknown. We identified a preweaning interval during which dietary antigens are assimilated by the colonic immune system. This interval is under maternal control via temporal changes in breast milk, coincides with an influx of naive T cells into the colon, and is followed by the development of a long-lived population of colonic peripherally derived Tregs (pTregs) that can be specific for dietary antigens encountered during this interval. Desynchronization of mothers and offspring produced durable deficits in these pTregs, impaired tolerance to dietary antigens introduced during and after this preweaning interval, and resulted in spontaneous Th2 responses. These effects could be rescued by pTregs from the periweaning colon or by Tregs generated in vitro using periweaning colonic antigen-presenting cells. These findings demonstrate that mothers and their offspring are synchronized for the development of a balanced immune system