Preeclampsia is a life-threatening complication of pregnancy that occurs four times more frequently in the presence of maternal diabetes. The anti-angiogenic factor soluble fms-like tyrosine kinase-1 (sFlt1), released from the placenta, plays a crucial role in PE development. Alpha 2-adrenoceptor (A2AR) dysfunction has been reported in diabetes, and is implicated in the development of vascular complications. Furthermore, A2AR agonist antihypertensive agents are frequently used to treat patients with preeclampsia, whether they have a disease-modifying role is unclear. We hypothesized that A2AR dysfunction could underlie up-regulation of placental sFlt1 expression, thus ‘driving’ preeclampsia in diabetes. We treated cultured human trophoblasts (HTR8/SVneo) with a stressor often present in the diabetic vasculature, ‘heavily oxidized, glycated’ low-density lipoproteins (HOG-LDL), vs. native LDL (at 100 µg protein/ml) with or without the A2AR agonist, clonidine, and antagonist, yohimbine (24h; both drugs at 10 μM and 100 μM). We determined α2A-, α2B- and α2C-AR mRNA expression (RT-PCR) and immunostaining; sFlt1 mRNA expression and protein release (ELISA); and cell viability (Cell Counting Kit-8 assay). Experiments were repeated three times independently. We found that all three A2AR subtypes were expressed in human trophoblasts. HOG- vs. N-LDL increased sFlt1 mRNA expression (2.0-fold, p<0.001) and protein release (2.5-fold, p<0.01), but neither clonidine nor yohimbine had any effect at either dose. Neither HOG- nor N-LDL altered A2AR expression or cell viability. Overall, the data confirm that modified lipoproteins may promote PE development in women with diabetes via upregulation and release of sFlt1, but do not provide clear evidence that A2ARs are implicated in this process. Further work will investigate whether A2ARs may be modified by other stressors of diabetes, and whether they may affect non-sFlt1 mechanisms for PE.
R.P. Chow: None. J. Zhao: None. T. Curtis: None. T. Lyons: None. J. Yu: None.