A C TA Obstetricia et Gynecologica
AOGS LE TT E R TO THE EDIT O R
Influence of caffeine on the expression of human chorionic gonadotropin and progesterone receptors in human trophoblast cell lines
Sir More than 75% of pregnant women consume drinks containing caffeine such as coffee, tea, and soft drinks (1). Although many studies have reported that caffeine induces miscarriage, congenital malformations, fetal growth retardation or preterm birth, studies examining the mechanism by which caffeine functions during pregnancy have been rarely reported. Serum hCG or progesterone are the hormones necessary to maintain the pregnancy and their measurements were reported to be useful for predicting first trimester abortions (2). Progesterone receptor antagonists can induce abortion or labor by increasing myometrial contractility and excitability throughout pregnancy (3). The human progesterone receptor (PGR) with which progesterone functions, consists of two major isoforms, PGR-A and PGR-B. The functional progesterone withdrawal hypothesis suggests that PGR-B is expressed at much higher levels than PGR-A throughout pregnancy and that labor is induced by an increase in the myometrial PGR-A to PGR-B ratio (3). However, no studies have examined the relation between caffeine and hCG or PGR during pregnancy. Therefore, we evaluated the effects of caffeine on the expression of hCG, which plays a critical role in the maintenance of early pregnancy, and PGR, which determines the actions of progesterone throughout pregnancy and parturition. HTR-8/SVneo cells, the human first-trimester extravillous trophoblast cell line, which has an extended lifespan after transfection with SV40 large T antigen, and JEG-3 cells, human choriocarcinoma cells, were stimulated for 24 h with caffeine at final concentrations of 0.01–1000 lmol/L. Quantitative real-time RT-PCR and Western blotting were used to measure the expression of hCG and PGR. In both cell lines, hCG-beta mRNA expression did not differ between the experimental groups and the control. The ratio of PGR-B to PGR-AB mRNA levels did not differ in any group compared with the control in HTR-8/SVneo cells, but it decreased in JEG-3 cells treated with 10–1000 lmol/L caffeine. PGR-A protein was not detected in either cell line. hCG-beta and PGR-B protein expression did not differ in any of the groups compared with the control. Pregnant women are recommended to limit caffeine consumption to a maximum daily intake of 200 mg (4). When a human is exposed to 100–200 mg of caffeine (one to two cups of coffee), plasma caffeine levels correspond to 1–3 lg/ mL (5). Therefore, in the current study, low to high concentrations of caffeine to evaluate caffeine concentrations safe
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for pregnancy were tested. Our study demonstrated that caffeine did not affect hCG mRNA or protein expression in human trophoblast cell lines. Increasing caffeine levels to the highest tested concentration did not alter hCG expression. Our study also demonstrated the dominant expression of PGR-B compared with PGR-A in human trophoblast cell lines, supporting previous reports. In human choriocarcinoma cells, PGR-B mRNA expression significantly decreased after treatment with caffeine and was drastically decreased at high concentrations of caffeine. Consequently, the ratio of PGR-B to PGR-AB mRNA significantly decreased, indicating a shift from PGR-B to PGR-A expression in the groups treated with high concentrations of caffeine. Unfortunately, these changes were limited to mRNA and did not extend to the protein concentration. Additionally, HTR-8/SVneo cells showed no change after stimulation with caffeine. Based on the discrepancy in these results, we conclude that caffeine is not a significant regulator of PGR expression in human trophoblasts. To our knowledge, this is the first report evaluating the relation between caffeine and hCG or PGR during pregnancy. Caffeine appears not to be a direct regulator of hCG expression in human trophoblasts. The relation between caffeine and PGRs was inconsistent in human trophoblast cell lines, suggesting the necessity of further studies.
Bang Hyun Lee1, Tae Chul Park2 and Hee Joong Lee2,* Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seoul National University, and 2 Department of Obstetrics & Gynecology, Catholic University of Korea, Seoul, Korea 1
*Corresponding Author: Hee Joong Lee E-mail: [email protected] DOI: 10.1111/aogs.12478
References 1. Eskenazi B. Caffeine – filtering the facts. N Engl J Med. 1999;341:1688–9. 2. Osmanagaoglu MA, Erdogan I, Eminagaoglu S, Karahan SC, Ozgun S, Can G, et al. The diagnostic value of
ª 2014 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 93 (2014) 1334–1335
Letter to the Editor
beta-human chorionic gonadotropin, progesterone, CA125 in the prediction of abortions. J Obstet Gynaecol. 2010;30:288–93. 3. Mesiano S, Wang Y, Norwitz ER. Progesterone receptors in the human pregnancy uterus: do they hold the key to birth timing? Reprod Sci. 2011;18:6–19.
4. ACOG. ACOG Committee Opinion No. 462: moderate caffeine consumption during pregnancy. Obstet Gynecol. 2010;116(2 Pt 1):467–8. 5. Brent RL, Christian MS, Diener RM. Evaluation of the reproductive and developmental risks of caffeine. Birth Defects Res B Dev Reprod Toxicol. 2011;92:152–87.
ª 2014 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 93 (2014) 1334–1335
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Copyright of Acta Obstetricia et Gynecologica Scandinavica is the property of WileyBlackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
AOGS LE TT E R TO THE EDIT O R
Influence of caffeine on the expression of human chorionic gonadotropin and progesterone receptors in human trophoblast cell lines
Sir More than 75% of pregnant women consume drinks containing caffeine such as coffee, tea, and soft drinks (1). Although many studies have reported that caffeine induces miscarriage, congenital malformations, fetal growth retardation or preterm birth, studies examining the mechanism by which caffeine functions during pregnancy have been rarely reported. Serum hCG or progesterone are the hormones necessary to maintain the pregnancy and their measurements were reported to be useful for predicting first trimester abortions (2). Progesterone receptor antagonists can induce abortion or labor by increasing myometrial contractility and excitability throughout pregnancy (3). The human progesterone receptor (PGR) with which progesterone functions, consists of two major isoforms, PGR-A and PGR-B. The functional progesterone withdrawal hypothesis suggests that PGR-B is expressed at much higher levels than PGR-A throughout pregnancy and that labor is induced by an increase in the myometrial PGR-A to PGR-B ratio (3). However, no studies have examined the relation between caffeine and hCG or PGR during pregnancy. Therefore, we evaluated the effects of caffeine on the expression of hCG, which plays a critical role in the maintenance of early pregnancy, and PGR, which determines the actions of progesterone throughout pregnancy and parturition. HTR-8/SVneo cells, the human first-trimester extravillous trophoblast cell line, which has an extended lifespan after transfection with SV40 large T antigen, and JEG-3 cells, human choriocarcinoma cells, were stimulated for 24 h with caffeine at final concentrations of 0.01–1000 lmol/L. Quantitative real-time RT-PCR and Western blotting were used to measure the expression of hCG and PGR. In both cell lines, hCG-beta mRNA expression did not differ between the experimental groups and the control. The ratio of PGR-B to PGR-AB mRNA levels did not differ in any group compared with the control in HTR-8/SVneo cells, but it decreased in JEG-3 cells treated with 10–1000 lmol/L caffeine. PGR-A protein was not detected in either cell line. hCG-beta and PGR-B protein expression did not differ in any of the groups compared with the control. Pregnant women are recommended to limit caffeine consumption to a maximum daily intake of 200 mg (4). When a human is exposed to 100–200 mg of caffeine (one to two cups of coffee), plasma caffeine levels correspond to 1–3 lg/ mL (5). Therefore, in the current study, low to high concentrations of caffeine to evaluate caffeine concentrations safe
1334
for pregnancy were tested. Our study demonstrated that caffeine did not affect hCG mRNA or protein expression in human trophoblast cell lines. Increasing caffeine levels to the highest tested concentration did not alter hCG expression. Our study also demonstrated the dominant expression of PGR-B compared with PGR-A in human trophoblast cell lines, supporting previous reports. In human choriocarcinoma cells, PGR-B mRNA expression significantly decreased after treatment with caffeine and was drastically decreased at high concentrations of caffeine. Consequently, the ratio of PGR-B to PGR-AB mRNA significantly decreased, indicating a shift from PGR-B to PGR-A expression in the groups treated with high concentrations of caffeine. Unfortunately, these changes were limited to mRNA and did not extend to the protein concentration. Additionally, HTR-8/SVneo cells showed no change after stimulation with caffeine. Based on the discrepancy in these results, we conclude that caffeine is not a significant regulator of PGR expression in human trophoblasts. To our knowledge, this is the first report evaluating the relation between caffeine and hCG or PGR during pregnancy. Caffeine appears not to be a direct regulator of hCG expression in human trophoblasts. The relation between caffeine and PGRs was inconsistent in human trophoblast cell lines, suggesting the necessity of further studies.
Bang Hyun Lee1, Tae Chul Park2 and Hee Joong Lee2,* Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seoul National University, and 2 Department of Obstetrics & Gynecology, Catholic University of Korea, Seoul, Korea 1
*Corresponding Author: Hee Joong Lee E-mail: [email protected] DOI: 10.1111/aogs.12478
References 1. Eskenazi B. Caffeine – filtering the facts. N Engl J Med. 1999;341:1688–9. 2. Osmanagaoglu MA, Erdogan I, Eminagaoglu S, Karahan SC, Ozgun S, Can G, et al. The diagnostic value of
ª 2014 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 93 (2014) 1334–1335
Letter to the Editor
beta-human chorionic gonadotropin, progesterone, CA125 in the prediction of abortions. J Obstet Gynaecol. 2010;30:288–93. 3. Mesiano S, Wang Y, Norwitz ER. Progesterone receptors in the human pregnancy uterus: do they hold the key to birth timing? Reprod Sci. 2011;18:6–19.
4. ACOG. ACOG Committee Opinion No. 462: moderate caffeine consumption during pregnancy. Obstet Gynecol. 2010;116(2 Pt 1):467–8. 5. Brent RL, Christian MS, Diener RM. Evaluation of the reproductive and developmental risks of caffeine. Birth Defects Res B Dev Reprod Toxicol. 2011;92:152–87.
ª 2014 Nordic Federation of Societies of Obstetrics and Gynecology, Acta Obstetricia et Gynecologica Scandinavica 93 (2014) 1334–1335
1335
Copyright of Acta Obstetricia et Gynecologica Scandinavica is the property of WileyBlackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
