Expressionsanalyse der nukleären Rezeptoren PPAR-α/γ-1/γ-2 und der Transkriptionsfaktoren T-bet und GATA-3 nach Stimulation von dermalen Endothelzellen mit den Weichmacher, Di(2-ethylhexyl)phthalat-Metaboliten 2-Ethylhexanol und 4-Heptanon

Hintergrund: Di(2-ethylhexyl) phthalate (DEHP) als Weichmacher aus der Familie der Phthalate ist bekannt für seinen schädlichen Einfluss auf Organe wie Herz, Leber und die Geschlechtsorgane. Im Gegensatz zu anderen Weichmachern bildet ausschließlich DEHP die Metabolite 2-Ethylhexanol (2EH) und 4-Hep...

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Bibliographic Details
Main Author: Dutescu, Ralf Michael
Contributors: Wahl, H. G. (Prof. Dr. Dr.) (Thesis advisor)
Format: Doctoral Thesis
Published: Philipps-Universität Marburg 2011
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Purpose: Di(2-ethylhexyl) phthalate (DEHP) is known to elicit marked impact on the heart, liver and lung and the reproductive system. In contrast to other members of the phthalates 2-ethylhexanole (2EH) and 4-heptanone (4HP) result solely from the DEHP metabolism and express there own distinctive toxicity. Since 2EH and 4HP are biodistributed via the vascular system we looked at the expression of nucleic receptors in endothelial cells after expositor to 2EH and 4HP. Methods: MEHC1 cells were cultivated and stimulated over 24h with 2-EH (500, 1000, 2000μg/ml) and 4-HP (250, 500, 1000, 2000μg/ml) and subsequently harvested for real time PCR. Transcription factors PPAR-α, γ-1, γ -2, T-bet and GATA-3 expression was quantified relative to a standard curve of known DNA-concentrations and compared to the expression pattern of unstimulated cells. Results: Data showed an inhibition of PPAR-α γ-1 and γ -2 after 2-EH exposure (500, 1000 μg/ml) with up regulation of PPAR-α and downregluation of PPAR γ-1 and γ -2 in 4-HP (500, 1000 μg/ml) incubated cells. GATA-3 was stimulated by 2-ETH and 4-HP in all concentations. The 2000 μg/ml 2-EH as well as 4HP yielded low cDNA levels indicating cell death. T-bet was barely detectable in 4HP stimulated cells. Discussion: It is assumed that PPARs cause vasodilation. Results suggest that 2-ETH as well as 4-HP present an oppositional impact on vascular tonus. GATA-3 has been shown to reduce the extravasation of immuno cells by inhibiting VCAM expression. Here we see a conflictive influence of 2EH comared to 4HP on GATA-3 expression. Future 2EH and 4HP in-vivo co-stimulation experiments could clarify witch metabolite outbalance the other on it’s impact on vascular function. So far the shown toxicity supports the idea of restricting the widespread use of DEHP.