RESUMO
BACKGROUND & AIMS: TGR5 (Gpbar-1) is a plasma membrane-bound bile acid receptor expressed in several tissues, including liver, intestine and brain. High levels of TGR5 mRNA have been detected in human and rodent placenta, however, localization of the TGR5 protein has not been studied in this tissue. We aimed at characterizing TGR5 expression in placental tissue and investigated the effect of bile acids and progesterone metabolites, which accumulate during intrahepatic cholestasis of pregnancy (ICP), on receptor expression and localization. METHODS: TGR5 mRNA levels and cell-specific localization were determined by quantitative PCR and immunofluorescence, respectively. RESULTS: In human term placentas, TGR5 was mainly localized in fetal macrophages and to a lower extent in trophoblasts. In placentas from ICP patients and pregnant rats with obstructive cholestasis a marked down-regulation of TGR5 mRNA expression was observed. However, the cell-specific distribution of the TGR5 protein was unaffected. Besides bile acids, progesterone and its metabolites (5α-pregnan-3α-ol-20-one/5α-pregnan-3ß-ol-20-one), which increase in serum during ICP, were able to dose-dependently activate TGR5. In addition, progesterone metabolites but not their sulfated derivatives nor taurolithocholic acid, significantly down-regulated TGR5 mRNA and protein expression in isolated human macrophages and a macrophage-derived cell line. CONCLUSION: Since fetal macrophages and trophoblast cells are exposed to changes in the flux of compounds across the placental barrier, the expression of TGR5 in these cells together with its sensitivity to bile acids and progesterone metabolites regarding receptor activity and mRNA expression suggest that TGR5 may play a role in the effect of maternal cholestasis on the placenta.
Assuntos
Colestase Intra-Hepática/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Macrófagos/metabolismo , Placenta/metabolismo , Complicações na Gravidez/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Trofoblastos/metabolismo , Animais , Ácidos e Sais Biliares/metabolismo , Células Cultivadas , Colestase Intra-Hepática/imunologia , Colestase Intra-Hepática/patologia , Modelos Animais de Doenças , Feminino , Genes Reporter , Células HEK293 , Humanos , Ativação de Macrófagos , Macrófagos/citologia , Macrófagos/imunologia , Macrófagos/patologia , Placenta/imunologia , Placenta/patologia , Gravidez , Complicações na Gravidez/imunologia , Complicações na Gravidez/patologia , Progesterona/análogos & derivados , Progesterona/metabolismo , Ratos , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/antagonistas & inibidores , Receptores Acoplados a Proteínas G/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Trofoblastos/imunologia , Trofoblastos/patologiaRESUMO
Objective, accurate, non-intrusive measurement of in vitro cell growth was realized through microcomputerized video image analysis. Recently-released video and digitizing hardware and software were incorporated into an analytical system which accurately quantified visual differences between cultures on a cell number or fresh mass basis. Sequential measurements during culture incubation further detected and quantified subtle changes in colony area and density resulting from growth. Each measurement was acquired rapidly, without encroaching on the in vitro environment, so cell growth was undisturbed. Custom software routines coordinated the quantification of this detailed record into precise cumulative growth curves.