Orchestration between ILC2s and Th2 cells in shaping type 2 immune responses

Abstract

The type 2 immune response is critical for host defense against large parasites such as helminths. On the other hand, dysregulation of the type 2 immune response may cause immunopathological conditions, including asthma, atopic dermatitis, rhinitis, and anaphylaxis. Thus, a balanced type 2 immune response must be achieved to mount effective protection against invading pathogens while avoiding immunopathology. The classical model of type 2 immunity mainly involves the differentiation of type 2 T helper (Th2) cells and the production of distinct type 2 cytokines, including interleukin-4 (IL-4), IL-5, and IL-13. Group 2 innate lymphoid cells (ILC2s) were recently recognized as another important source of type 2 cytokines. Although eosinophils, mast cells, and basophils can also express type 2 cytokines and participate in type 2 immune responses to various degrees, the production of type 2 cytokines by the lymphoid lineages, Th2 cells, and ILC2s in particular is the central event during the type 2 immune response. In this review, we discuss recent advances in our understanding of how ILC2s and Th2 cells orchestrate type 2 immune responses through direct and indirect interactions. Keywords: Type 2 immune response; type 2 T helper cell (Th2); Group 2 innate lymphoid cell (ILC2); Allergy and asthma Cellular & Molecular Immunology (2019) 16:225-235; https://doi.

CD4 T Helper Cell Subsets and Related Human Immunological Disorders

“…Th2 cells are mainly involved in host defense against large extracellular pathogens, such as helminths. Naïve CD4 T cells after receiving signals from DCs may differentiate into Th2 cells after their activation [30]. IL-2 and IL-4 are two important cytokines during Th2 cell differentiation, particularly in vitro.…”

“…Among the CD4 T subsets possessing helper functions (Figure 1), Th1 cells induce type 1 responses to protect against intracellular pathogens such as bacteria, viruses, and protozoa by activating type 1 macrophages (M1) [5]. Th2 cells are involved in type 2 responses to fight infections by parasites such as helminths by activating type 2 microphages (M2), as well as the recruitment of eosinophils, basophils, and mast cells to the sites of infections [30]. Th17 cells mediate type 3 responses for the clearance of extracellular bacteria and fungi by orchestrating sustained neutrophil recruitment and an induction of antimicrobial peptide production by epithelial cells of barrier tissues such as intestines, lungs, and skin [31].…”

Eosinophils Control Liver Damage by Modulating Immune Responses Against Fasciola hepatica

“…In this study, we investigate the role of eosinophils during F. hepatica infection and show that they are beneficial to the host by promoting an effective immune response that partially controls liver damage. Accumulation of eosinophils is a well-documented feature of helminth infections since these cells can be vital to develop Th2 immune responses against parasitic helminths (22). However, their role during infection is rather controversial.…”

Group 2 Innate Lymphoid Cells Promote Development of T Follicular Helper Cells and Initiate Allergic Sensitization to Peanuts

“…Although the roles for ILC2s in innate immunity and tissue homeostasis have been well established (10), their roles in promoting or regulating adaptive immunity have only been recognized recently. For example, ILC2s and CD4 + Th2 cells may interact directly through cellular contact through MHCII and costimulatory molecules (26,38,39). Alternatively, ILC2s may indirectly promote adaptive immunity by activating DCs.…”