Adipocyte-derived PGE2 is required for intermittent fasting–induced Treg proliferation and improvement of insulin sensitivity
Chunqing Wang, Xing Zhang, Liping Luo, Yan Luo, Xin Yang, Xiaofeng Ding, Lu Wang, Huyen Le, Lily Elizabeth R. Feldman, Xuebo Men, Cen Yan, Wendong Huang, Yingmei Feng, Feng Liu, Xuexian O. Yang, Meilian Liu
Chunqing Wang, Xing Zhang, Liping Luo, Yan Luo, Xin Yang, Xiaofeng Ding, Lu Wang, Huyen Le, Lily Elizabeth R. Feldman, Xuebo Men, Cen Yan, Wendong Huang, Yingmei Feng, Feng Liu, Xuexian O. Yang, Meilian Liu
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Research Article Metabolism

Adipocyte-derived PGE2 is required for intermittent fasting–induced Treg proliferation and improvement of insulin sensitivity

Abstract

The intermittent fasting (IF) diet has profound benefits for diabetes prevention. However, the precise mechanisms underlying IF’s beneficial effects remain poorly defined. Here, we show that the expression levels of cyclooxygenase-2 (COX-2), an enzyme that produces prostaglandins, are suppressed in white adipose tissue (WAT) of obese humans. In addition, the expression of COX-2 in WAT is markedly upregulated by IF in obese mice. Adipocyte-specific depletion of COX-2 led to reduced fractions of CD4+Foxp3+ Tregs and a substantial decrease in the frequency of CD206+ macrophages, an increase in the abundance of γδT cells in WAT under normal chow diet conditions, and attenuation of IF-induced antiinflammatory and insulin-sensitizing effects, despite a similar antiobesity effect in obese mice. Mechanistically, adipocyte-derived prostaglandin E2 (PGE2) promoted Treg proliferation through the CaMKII pathway in vitro and rescued Treg populations in adipose tissue in COX-2–deficient mice. Ultimately, inactivation of Tregs by neutralizing anti-CD25 diminished IF-elicited antiinflammatory and insulin-sensitizing effects, and PGE2 restored the beneficial effects of IF in COX-2–KO mice. Collectively, our study reveals that adipocyte COX-2 is a key regulator of Treg proliferation and that adipocyte-derived PGE2 is essential for IF-elicited type 2 immune response and metabolic benefits.

Authors

Chunqing Wang, Xing Zhang, Liping Luo, Yan Luo, Xin Yang, Xiaofeng Ding, Lu Wang, Huyen Le, Lily Elizabeth R. Feldman, Xuebo Men, Cen Yan, Wendong Huang, Yingmei Feng, Feng Liu, Xuexian O. Yang, Meilian Liu

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Figure 6

Adipocyte COX-2 promotes resident Treg proliferation through PGE2.

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Adipocyte COX-2 promotes resident Treg proliferation through PGE2. (A) C...
(A) COX-2 deficiency suppressed the secretion levels of PGE2 and PGI2 in primary adipocytes. COX-2–KO and control (Ctrl) primary adipocytes were changed to fresh medium and cultured for 2 hours. Medium was collected and used to determine the levels of PGE2 and PGI2, using an ELISA kit. (B, C, E, and F) AT Tregs were isolated from AT for these studies. Treatment of PGE2 but not PGD2 and PGI2 increased the population of Foxp3+ Tregs in a dose-dependent manner (B), and treatment of 100 nM PGE2 induced proliferation of Tregs as indicated by the staining of Ki67 (C). Intracellular Ki67+ and Foxp3+ Tregs were determined by flow cytometry analysis. AT Tregs were treated with DMSO, PGD2, PGE2, or PGI2, with indicated doses for 24 hours. *P < 0.05 compared with the group without treatment. (D) Treatment of PGE2 stimulated activation of PKA and CaMKII in differentiated Tregs in a dose-dependent manner. CD4+-naive T cells were isolated from a single-cell suspension from lymph nodes and spleens and then differentiated into CD4+Foxp3+ Tregs. Differentiated Tregs were treated, or not, with PGE2 for 1 hour. Representative data from 3 independent experiments are reported. (E) PGE2 treatment stimulated phosphorylation of CaMKII in AT Tregs. n = 3/group. (F) Inhibiting PKA by 5 μM KT 5720 or inhibiting CaMKII by 5 μM TATCN21 suppressed PGE2-treatment–induced proliferation of AT Tregs. AT Tregs were treated with KT 5720 or TATCN21 for 1 hour, followed by co-treatment with PGE2 for 24 hours. n = 3/group. CaMKIIγ deficiency blocked PGE2-stimulated CD4+Foxp3+ Treg proliferation, indicated by Ki67 expression (G) and total Treg fraction (H). Primary Tregs were isolated from AT of CaMKIIγ-KO and WT mice and treated with 100 nM PGE2 for 24 hours, followed by flow cytometry analysis. (A–C) The t test was used for data analysis. (F–H) ANOVA was used for data analysis. Data are reported as mean ± SEM. *P < 0.05; **P < 0.01.