Exogenous soluble VEGF receptor-1 (sFlt-1) regulates Th1/Th2 cytokine production from normal placental explants via intracellular calcium.
OBJECTIVE
The increase of soluble VEGF-Receptor 1 (sFlt-1) is thought to contribute to the pathogenesis of preeclampsia. Soluble VEGF-Receptor 1 binds to circulating free VEGF and PLGF and this cascade is associated with endothelial dysfunction, a prominent feature of preeclampsia. Preeclampsia is also associated with excessive maternal response to pro-inflammatory stimuli manifesting as an imbalance of Th1/Th2 cytokine production at the maternal-fetal interface. Whether increased sFlt-1 expression has any effect on placental production of Th1/Th2 cytokines IL-10 and TNF-alpha is yet to be investigated. The aim of this study is to examine if exogenous sFlt-1 can regulate Th1/Th2 cytokines IL-10 and TNF-alpha production from normal placental explants via intracellular calcium release.


METHODS
Placental explants were taken from the decidual surface of normal non-laboured term placentas (n = 11).Villous explants were cultured with increasing concentrations of sFlt-1. The dose effect of sFlt-1 on placental Th1 and Th2 cytokine production (TNF-alpha and IL-10) were examined. Free PLGF, VEGF and sFlt-1 concentrations in the conditioned medium were also measured. Intracellular calcium blocker, 1,2-bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid, tetra(acetoxymethyl)-ester (BAPTA/AM) was applied to investigate whether the changes in cytokine concentration were mediated by intracellular free calcium.


RESULTS
Placental IL-10 and TNF-alpha production were significantly increased after sFlt-1 incubation. The increase in IL-10 can be inhibited by BAPTA/AM. Soluble Flt-1 and free PLGF concentration in the conditioned medium was not changed. Free VEGF concentration in the conditioned medium was not detectable.


CONCLUSIONS
Exogenous sFlt-1 can increase TNF-alpha and IL-10 production from normal placental explants. The change in Th1/Th2 cytokine level may be mediated by intracellular free calcium.
Vascular Immunology Research Laboratory, The Heart Research Institute, University of Sydney, NSW 2050, Australia. bei_xu2001@yahoo.com
Bei
B
Xu
Charlene
C
Thornton
Jane
J
Tooher
Annemarie
A
Hennessy
D002118:Calcium / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D016753:Interleukin-10 / Q000096:biosynthesis*; D009924:Organ Culture Techniques; D010920:Placenta / Q000187:drug effects / Q000378:metabolism*; D010926:Placental Hormones / Q000378:metabolism; D011247:Pregnancy; D020033:Protein Isoforms / Q000008:administration & dosage / Q000378:metabolism; D018709:Statistics, Nonparametric; D018417:Th1 Cells / Q000378:metabolism*; D018418:Th2 Cells / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000008:administration & dosage / Q000378:metabolism*
C064980:GH2 protein, human; D010926:Placental Hormones; D020033:Protein Isoforms; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D013006:Growth Hormone; D040281:Vascular Endothelial Growth Factor Receptor-1; D002118:Calcium