Objectives: Preeclampsia (PE) is a serious complication of human pregnancy affecting 2-8% of pregnancy worldwide. Women who have had PE, especially early-onset PE (EPE, occurring ≤34 weeks of gestation), have an increased risk of cardiovascular disease (CVD) later in life. However, how PE is linked to CDV is not well understood. HtrA4 is expressed specifically by the placenta, and is significantly elevated in the EPE circulation [1]. We have also reported that elevated circulating HtrA4 can inhibit proliferation of endothelial cells as well as endothelial progenitor cells (EPCs), which play a critical role in endothelial regeneration [2]. We thus hypothesized that elevated circulating HtrA4 may promote endothelial aging, which is the biggest risk factor of CVD.
Aim: To examine whether HtrA4 alters endothelial expression of genes associated with senescence.
Methods: Human umbilical vein endothelial cells (HUVECs) and primary EPCs isolated from cord blood of healthy pregnancies were used as models. HUVECs were treated with HtrA4 for 48h and screened with a cell senescence PCR array. The results were then validated by RT-PCR and ELISA in HUVECs and EPCs treated with different doses of HtrA4 for 24 and 48h.
Results: The array revealed that HtrA4 altered HUVEC expression of 21 genes associated with senescence, 6 upregulated and 15 downregulated. All these genes were validated by RT-PCR. In particular, HtrA4 significantly up-regulated IGFBP3, SERPINE1 and SERPINB2, which all promote senescence. IGFBP3 protein was also significantly elevated in HtrA4-treated HUVEC media. Conversely, a number of genes including CDKN2C and CHEK2 that regulate cell cycle, were downregulated by HtrA4. Many of these genes also showed a similar trend of change in EPCs following HtrA4 treatment, although the majority did not reach a statistical significance.
Conclusions: High levels of placenta-derived HtrA4 detected in EPE circulation may promote premature endothelial aging to contribute to CVD development.