Elevated circulating HtrA4 in preeclampsia may alter endothelial expression of senescence genes

Introduction: Preeclampsia (PE) is a serious complication of human pregnancy. Women who have had PE, especially early-onset PE (EPE), have an increased risk of cardiovascular disease (CVD) later in life. However, how PE is linked to CVD is not well understood. We previously reported that HtrA4, a placenta-specific protease, is significantly elevated in EPE, and inhibits the proliferation of endothelial cells as well as endothelial progenitor cells (EPCs). This can potentially impair endothelial repair and regeneration, leading to endothelial aging, which is a major risk factor of CVD. In this study, we examined whether HtrA4 can alter endothelial expression of senescence genes. Methods: Human umbilical vein endothelial cells (HUVECs) and primary EPCs isolated from cord blood of healthy pregnancies were used as in vitro models. Firstly, HUVECs were treated with HtrA4 at the highest levels detected in EPE for 48h and screened with a senescence PCR array. The results were then validated by RT-PCR and ELISA in HUVECs and EPCs treated with HtrA4 for 24 and 48h. Results: We observed that HtrA4 significantly up-regulated IGFBP3, SERPINE1 and SERPINB2, which all promote senescence. IGFBP-3 protein was also significantly elevated in the media of HtrA4-treated HUVECs. Conversely, a number of genes including CDKN2C, PCNA, CALR, CHEK2 and NOX4 were downregulated by HtrA4. Many of these genes also showed a similar trend of change in EPCs following HtrA4 treatment. Discussion: Elevation of placenta-derived HtrA4 in PE alters the expression of endothelial genes to promote cellular senescence and may contribute to premature endothelial aging.