Figure 4. COX-2 deficiency suppressed IF-induced Treg proliferation and improvement of insulin resistance.

A HFD was fed to 6-week-old male COX-2–KO and control (Ctrl) mice for 8 weeks followed by IF (n = 6–8/group) for 30 days. (A) IF led to a 32.6% loss of fat mass and a 18.7% loss of body mass but not lean mass in Ctrl mice, and the antiobesity effect was not significantly affected by COX-2 deficiency. (B) IF-induced mass loss in eWAT and BAT was little affected, whereas the effects on iWAT and liver were suppressed in COX-2–KO mice compared with Ctrl mice. (C) Representative images of eWAT, iWAT, BAT, and liver in HFD-fed COX-2–KO and Ctrl mice before and after IF. COX-2 deficiency alleviated IF-induced increase in the Treg fraction (D) and the proportion of Tregs in CD4⁺ cells (E); suppressed the inhibitory effects of IF on the γδT cell fraction (F) and the proportion of γδT cells in CD3⁺ cells (G); and diminished the inducing effect of IF on mRNA levels of Foxp3, GATA3, and TGFβ3 with little effect on IL-10, TGFβ1, and TGFβ2 (H) in eWAT. (I) COX-2 deficiency diminished IF-improved glucose tolerance. (J) COX-2 deficiency diminished IF-improved insulin tolerance. (K and L) Insulin-stimulated phosphorylation of Akt at Thr308 (T308) and Ser473 (S473) in the liver of COX-2–KO and Ctrl mice treated with or without IF. n = 4/group. *P < 0.05 and **P < 0.01 for Ad vs. IF in Ctrl mice; ^#P < 0.05 for Ctrl vs. KO mice with Ad diet; ^$P < 0.05 for Ad vs. IF in KO mice. ANOVA was used to analyze all the data in this figure. (A, B, and D–H) Data are presented as mean ± SEM. * P < 0.05; **P < 0.01.