Regulatory T cells use arginase 2 to enhance their metabolic fitness in tissues
Margaret M. Lowe, … , Tiffany C. Scharschmidt, Michael D. Rosenblum
Margaret M. Lowe, … , Tiffany C. Scharschmidt, Michael D. Rosenblum
Published December 19, 2019
Citation Information: JCI Insight. 2019;4(24):e129756. https://doi.org/10.1172/jci.insight.129756.
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Research Article Immunology Metabolism

Regulatory T cells use arginase 2 to enhance their metabolic fitness in tissues

Abstract

Distinct subsets of Tregs reside in nonlymphoid tissues where they mediate unique functions. To interrogate the biology of tissue Tregs in human health and disease, we phenotypically and functionally compared healthy skin Tregs with those in peripheral blood, inflamed psoriatic skin, and metastatic melanoma. The mitochondrial enzyme, arginase 2 (ARG2), was preferentially expressed in Tregs in healthy skin, increased in Tregs in metastatic melanoma, and reduced in Tregs from psoriatic skin. ARG2 enhanced Treg suppressive capacity in vitro and conferred a selective advantage for accumulation in inflamed tissues in vivo. CRISPR-mediated deletion of this gene in primary human Tregs was sufficient to skew away from a tissue Treg transcriptional signature. Notably, the inhibition of ARG2 increased mTOR signaling, whereas the overexpression of this enzyme suppressed it. Taken together, our results suggest that Tregs express ARG2 in human tissues to both regulate inflammation and enhance their metabolic fitness.

Authors

Margaret M. Lowe, Ian Boothby, Sean Clancy, Richard S. Ahn, Wilson Liao, David N. Nguyen, Kathrin Schumann, Alexander Marson, Kelly M. Mahuron, Gillian A. Kingsbury, Zheng Liu, Priscila Munoz Sandoval, Robert Sanchez Rodriguez, Mariela L. Pauli, Keyon Taravati, Sarah T. Arron, Isaac M. Neuhaus, Hobart W. Harris, Esther A. Kim, Uk Sok Shin, Matthew F. Krummel, Adil Daud, Tiffany C. Scharschmidt, Michael D. Rosenblum

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Figure 3

Arginase 2 is preferentially induced on “effector memory” Tregs in human peripheral blood and plays a role in Treg-mediated suppression.

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Arginase 2 is preferentially induced on “effector memory” Tregs in human...
(A) qRT-PCR of sort-purified healthy human skin Tregs, human skin CD4+ Teffs, healthy peripheral blood Tregs, and healthy peripheral blood CD4+ Teffs, quantifying ARG2 relative to housekeeping gene EIF3L (**P < 0.01, ***P < 0.005, ordinary 1-way ANOVA). (B) Flow cytometric quantification of ARG2 protein expression on peripheral blood Tregs compared with Tregs in healthy human skin (***P < 0.004, Student’s t test). (C) Representative flow cytometric plots of ARG2 protein expression on peripheral blood Tregs and CD4+ Teffs that were not stimulated (left) or stimulated for 4 days with soluble anti-CD3 and anti-CD28 in the presence of IL-2 (middle) or Tregs expanded over 7 days in vitro (Exp) compared with nonstimulated (NS) Tregs and Tregs after 4 days of anti-CD3/anti-CD28 stimulation (S) (right). Data are representative of at least 3 independent experiments. (D) Flow cytometric quantification of ARG2 protein expression in peripheral blood CD45RO+ “effector memory” or CD45RO– “resting” Tregs from 6 donors over 1, 2, 3, or 4 days of stimulation (****P < 0.001, 2-way repeated measures ANOVA). (E) In vitro Treg suppression assay showing the percentage of CFSE-labeled CD4+ Teffs remaining undivided after 3 days of stimulation with anti-CD3/anti-CD28, with or without preactivated peripheral blood Tregs (1:4 ratio) and/or increasing concentrations of the arginase inhibitor (ABH). Experiment performed with 3 replicates and is representative of 2 independent experiments (*P < 0.05, **P < 0.01, ordinary 1-way ANOVA).