Regulation of peroxisome proliferator-activated receptor-gamma expression in human eosinophils by estradiol.
BACKGROUND
Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a nuclear receptor that regulates not only adipogenesis but also immune reaction. We previously demonstrated that human eosinophils expressed functional PPARgamma, although the modulator of PPARgamma expression is less well understood. Because clinical studies have shown that the efficacy of PPARgamma agonists as insulin sensitizers is stronger in women than in men, we investigated whether sex hormones caused any changes in eosinophil PPARgamma expression levels.


METHODS
First, purified human peripheral blood eosinophils were cultured with 17beta-estradiol for 24 h, followed by PPARgamma measurement using a flow cytometer. Next, eosinophil PPARgamma expression and serum estradiol were studied in 10 healthy women during the menstrual and follicular phases to identify the physiological significance of estradiol. Eosinophil PPARgamma expression was also compared in 22 men, 21 non-pregnant women, and 15 pregnant women.


RESULTS
We observed that PPARgamma protein expression in eosinophils was significantly enhanced by 10(-6)M 17beta-estradiol. Although serum estradiol concentration was increased during the follicular phase, PPARgamma expression levels were not affected by the menstrual cycle. In addition, no significant differences in PPARgamma expression were observed in terms of sex and pregnancy.


CONCLUSIONS
These findings suggest that estradiol potentially upregulates eosinophil PPARgamma expression in vitro, although some other mechanisms might be involved in its regulation in vivo.
Ueki
Shigeharu
S
Department of Infection, Clinical Immunology and Laboratory Medicine, Akita University Graduate School of Medicine, Akita, Japan.
Oguma
Mariko
M
Usami
Atsuko
A
Kamada
Yumiko
Y
Kato
Hikari
H
Kamada
Rie
R
Takeda
Masahide
M
Ito
Wataru
W
Tanigai
Tomomi
T
Kayaba
Hiroyuki
H
Chihara
Junichi
J
D000328:Adult; D002478:Cells, Cultured; D004804:Eosinophils / Q000187:drug effects* / Q000378:metabolism; D004958:Estradiol / Q000097:blood / Q000494:pharmacology*; D005260:Female; D006801:Humans; D008297:Male; D047495:PPAR gamma / Q000096:biosynthesis*; D011247:Pregnancy; D014176:Protein Biosynthesis / Q000187:drug effects*; D012737:Sex Factors; D015854:Up-Regulation
D047495:PPAR gamma; D004958:Estradiol