Preeclampsia (PE) is a pregnancy-related hypertensive disorder that affects 5-8% of all pregnancies worldwide. Placental microRNA (miRNA) expression is known to be dysregulated during PE which includes miR-210. However, the role of miR-210 in the development of PE is still unknown. We have previously demonstrated STAT6, a transcription factor, to be a direct target of miR-210. In addition, STAT6 modulates levels of IL-4, an anti-inflammatory cytokine which is known to be beneficial during pregnancy. Given that the STAT6/IL-4 pathway is important for normal pregnancy, we hypothesized that an overexpression of miR-210 in mice will contribute to PE-like symptoms by inhibiting the STAT6/IL-4 pathway. Systolic blood pressures (SBP) were measured using the tail-cuff method on both WT (C57Bl/6J) and miR-210 TG mice. The miR-210 TG mice exhibited increased SBP compared to the WT mice (WT: 95±2 mmHg, miR-210 TG: 115±2.4 mmHg, p<0.05). The miR-210 TG mice also displayed endothelial dysfunction measured by aortic vascular reactivity using wire myography (WT: 93% miR-210 TG: 68% relaxation, p<0.05 vs. WT) and a significant increase in proteinuria (4 fold, p<0.05 vs. WT). Furthermore, the miR-210 TG mice exhibit placental necrosis and a significant increase in the number of malformed pups. Placental STAT6 levels decreased in miR-210 TG compared to WT mice (2.6 fold, p<0.05 vs. WT) as determined by immunoblotting. In addition, qRT-PCR analysis of the miR-210 TG placentas exhibited a (4.8 fold, p<0.05 vs. WT) decrease in IL-4 expression. Immunoblotting and immunohistochemistry (IHC) studies showed a decrease in IL-4 levels (2.4 fold, p<0.05 vs. WT) and immunoreactivity in the miR-210 TG placentas as well as. IHC studies in human placentas also showed a decrease in both IL-4 and STAT6. Based on our results, miR-210 overexpression induces PE-like symptoms including hypertension, endothelial dysfunction, proteinuria, and malformed pups in pregnant mice. In addition, miR-210 overexpression attenuated the STAT6/IL-4 anti-inflammatory pathway. Our data suggests that either targeting miR-210 or the STAT6/1L-4 pathway could be a potential therapeutic in mitigating the symptoms of PE.

Preeclampsia (PE) is an obstetric complication that is diagnosed by hypertension and proteinuria at or after 20 weeks of gestation. PE is a multifactorial disease, but it is widely accepted that impaired proangiogenic factors such as vascular endothelial growth factor (VEGF), placental growth factor (PlGF) and antiangiogenic factor such as soluble FMS-like tyrosine kinase-1 (sFlt1) or VEGF receptor-1 balance during pregnancy is linked to PE. sFlt1, a splice variant of Flt1 binds to either VEGF or PlGF and blocks their action. In addition, placental angiogenesis is known to be regulated by specific miRNAs that are typically dysregulated during PE highlighting the importance of these miRNAs in pregnancy disorders. miR-210 is upregulated in placentas and serum/plasma of PE women and is also known to modulate angiogenic pathways. Therefore, we hypothesized that miR-210 overexpression contributes to the development of PE-like symptoms by altering the angiogenic/antiangiogenic pathway. To this end, we demonstrate increased systolic blood pressure (SBP: miR-210 TG P = 115 ± 2 mm Hg vs. WT P = 95 ± 2 mm Hg, p<0.05), endothelial dysfunction and proteinuria in pregnant miR-210 TG mice as compared to control WT mice. Placental sFlt-1 levels increased and PlGF levels decreased in miR-210 TG mice as determined by immunoblotting. Immunohistochemistry (IHC) analysis demonstrated an increase in sFlt1 and a decrease in PlGF immunoreactivity in miR-210 TG placentas. Pregnant miR-210 TG mice exhibited increased serum levels of sFlt-1 as well as decreased PlGF as compared to pregnant WT mice. Furthermore, immunohistological analysis of stained human placental sections revealed an increase in sFlt-1 and a decrease in PlGF in pregnant miR-210 TG as compared to pregnant WT mice. To determine the placental etiology, human cytotrophoblasts (CTBs) overexpressing miR-210 demonstrated a decrease in PlGF while inhibition of miR-210 in CTBs using anti-miR-210 oligos increased the PlGF expression as determined by immunoblotting. These data taken together suggest that miR-210 modulates the angiogenic/antiangiogenic pathway and contributes to PE-like features in mice. Thus, targeting miR-210 by delivering anti-miR-210 oligos may prevent PE-like symptoms in pregnant women.