AHR and the Transcriptional Regulation of Type-17/22 ILC

Jacob S Lee,Marco Colonna,Marina Cella

doi:10.3389/fimmu.2012.00010

Abstract

Mucosal innate lymphoid cells (ILCs) are an emerging population of diverse and heterogeneous immune cells, all with the unique ability to mount a rapid response against invading pathogens. They are further divided into subsets based on their differing cell surface markers as well as in their functional specialization. In this review, we summarize recent reports describing the importance of the transcription factor aryl hydrocarbon receptor (AHR) in regulating the development of one of these subsets, the Type-17/22 ILCs, as well as in the organization of postnatal lymphoid structures. We discuss the mechanisms behind the AHR dependence for development in Type-17/22 ILCs as well as reviewing the proposed physiological ligands that are mediating this effect.

Highlights

INNATE LYMPHOID CELLS: HETEROGENEITY AND FUNCTIONAL SPECIALIZATIONMucosal innate lymphoid cells (ILCs) are a population of immune cells that has broad roles in host immunity as well as maintaining homeostasis between the host and its environment
Type-2 ILCs include “natural helper cells” (NH; Moro et al, 2010), “nuocytes” (Neill et al, 2010), innate helper type-2 (Ih2) cells (Price et al, 2010), and multipotent progenitor type-2 cells (MPPtype2; Saenz et al, 2010) which specialize in the production of IL-5 and IL-13
CPs and isolated lymphoid follicles (ILFs) from aryl hydrocarbon receptor (AHR) conditional deletion mutants driven by RORγt-Cre recombinase had the same phenotype as AHR null animals while these structures from AHR conditional deletion mutants driven by CD11c or Villin – Cre were unaffected (Kiss et al, 2011). These studies seem to indicate that while AHR is expressed in intestinal epithelial cells or other mucosal-associated immune populations, AHR signaling within RORγt expressing ILCs is critical for their development as well as the formation of CPs and ILFs

Summary

Introduction

INNATE LYMPHOID CELLS: HETEROGENEITY AND FUNCTIONAL SPECIALIZATIONMucosal innate lymphoid cells (ILCs) are a population of immune cells that has broad roles in host immunity as well as maintaining homeostasis between the host and its environment. Using various conditional deletion mutants for AHR, it was found that the requirement for AHR in the development of Type-17/22 ILCs (Kiss et al, 2011; Lee et al, 2011) as well as the organization of CPs and ILFs was intrinsic to RORγt expressing cells.

Results

Conclusion