Intestinal helminths skew dendritic cell development to counter the anti-helminth immune response

Intestinal dendritic cells (DC) orchestrate the adaptive immune response that balances protection against pathogens and tolerance towards harmless antigens. Yet, it remains largely unknown what molecular mechanisms underly this functional duality. Heligmosomoides polygyrus bakeri (Hpb) is a naturally occurring parasite in mice characterised by unique immune-evasion strategies that counter host protective immunity. Here, we utilised this unique infection environment to study mechanisms by which DC maintain the immune balance. In-depth characterisation of intestinal DC during Hpb infection revealed the emergence of distinct populations of DC that drive protective Th2 responses, versus others with immunoregulatory properties. We also identified that the skewing of intestinal DC towards immunoregulatory functions was due to TGFβ signalling via endogenous sources and by Hpb-produced TGFβ-mimic molecules. Thus, our results present a mechanistic explanation for Hpb's ability to modulate the adaptive immune system. Furthermore, these data offer an example of how heterogeneity within the DC compartment can determine the simultaneous generation of both pro- and anti-inflammatory immune responses.