Regulation of Peroxisome Proliferator-Activated Receptor-γ Expression in Human Eosinophils by Estradiol

Abstract

Background: Peroxisome proliferator-activated receptor-γ (PPARγ) is a nuclear receptor that regulates not only adipogenesis but also immune reaction. We previously demonstrated that human eosinophils expressed functional PPARγ, although the modulator of PPARγ expression is less well understood. Because clinical studies have shown that the efficacy of PPARγ agonists as insulin sensitizers is stronger in women than in men, we investigated whether sex hormones caused any changes in eosinophil PPARγ expression levels. Methods: First, purified human peripheral blood eosinophils were cultured with 17β-estradiol for 24 h, followed by PPARγ measurement using a flow cytometer. Next, eosinophil PPARγ expression and serum estradiol were studied in 10 healthy women during the menstrual and follicular phases to identify the physiological significance of estradiol. Eosinophil PPARγ expression was also compared in 22 men, 21 non-pregnant women, and 15 pregnant women. Results: We observed that PPARγ protein expression in eosinophils was significantly enhanced by 10^–6M 17β-estradiol. Although serum estradiol concentration was increased during the follicular phase, PPARγ expression levels were not affected by the menstrual cycle. In addition, no significant differences in PPARγ expression were observed in terms of sex and pregnancy. Conclusions: These findings suggest that estradiol potentially upregulates eosinophil PPARγ expression in vitro, although some other mechanisms might be involved in its regulation in vivo.

Docosahexaenoic Acid Exerts Anti-Inflammatory Action on Human Eosinophils through Peroxisome Proliferator-Activated Receptor-Independent Mechanisms

“…Since we previously reported on the constitutive expression of PPARγ on human eosinophils [14,23], the expression of PPARα was initially confirmed. As shown in figure 3a, purified eosinophils obtained from 4 different donors expressed PPARα at the mRNA and the protein levels (fig.…”

Suppressive effects of aryl-hydrocarbon receptor repressor on adipocyte differentiation in 3T3-L1 cells

“…AhRR is reported to attenuate estrogen receptor α-mediated transcription via direct interaction of AhRR with estrogen receptor α on an estrogen response element [26]. Estradiol is known to induce PPARγ expression in various types of tissues [27–29]. Therefore, suppressive effect of AhRR in estrogen signaling might be involved in the attenuation of PPARγ expression during adipogenesis.…”

Mediating Roles of PPARs in the Effects of Environmental Chemicals on Sex Steroids

“…Exogenous testosterone significantly inhibited the expression of PPAR γ in primary hepatocytes isolated from brown trout [ 11 ]. 17 β -Estradiol could regulate the expression of PPAR γ in human peripheral blood eosinophils [ 12 ]. Additionally, precursors of sex steroids also interact with PPARs.…”