PD-1 expression affects cytokine production by ILC2 and is influenced by peroxisome proliferator-activated receptor-γ.
IMMUNITY INFLAMMATION AND DISEASE 2019;
8:8-23. [PMID:
31742928 PMCID:
PMC7016838 DOI:
10.1002/iid3.279]
[Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 11/03/2019] [Accepted: 11/06/2019] [Indexed: 12/25/2022]
Abstract
Introduction
Innate lymphoid cells (ILCs) can provide early cytokine help against a variety of pathogens in the lungs and gastrointestinal tract. Type 2 ILC (ILC2) are comparable to T helper 2 cells found in the adaptive immune system, which secrete cytokines such as interleukin 5 (IL‐5) and IL‐13 and have been found to play roles in host defense against helminth infections and in allergic responses. Recent studies have identified that programmed cell death protein 1 (PD‐1) and peroxisome proliferator activated receptor‐γ (PPAR‐γ) are highly expressed by ILC2. We examined whether PD‐1 plays a role in ILC2 function and whether there was any connection between PD‐1 and PPAR‐γ
Methods
To ensure that only innate immune cells were present, ILC2 cells were examined from RAG1−/− and PD‐1−/−xRAG1−/− mice under steady‐state or following inoculation with IL‐33. We also tested ILC2 generated from bone marrow of RAG1−/− and PD‐1−/−xRAG1−/− mice for their production of cytokines. These in vitro‐derived ILC2 were also exposed to agonist and antagonist of PPAR‐γ.
Results
We found that ILC2 from PD‐1−/−xRAG1−/− mice had reduced frequencies of IL‐5 and IL‐13 producing cells both in vitro upon IL‐33 stimulation and in vivo following intraperitoneal administration of IL‐33 when compared with ILC2 from RAG1−/− mice. However, by adding IL‐2, IL‐25, and thymic stromal lymphopoietin to the in vitro cultures, the frequency of IL‐5 and IL‐13 expressing ILC2 from PD‐1−/−xRAG1−/− mice became similar to the frequency observed for ILC2 from RAG1−/− mice. In addition, PPAR‐γ agonists and antagonists were found to increase and decrease PD‐1 expression on ILC2 respectively.
Conclusions
These findings illustrate that chronic loss of PD‐1 plays a role in ILC2 function and PD‐1 expression can be modulated by PPAR‐γ.
Collapse