Exposure to Synthetic CpG DNA During Pregnancy Increases Expression and Activity of Cyclooxygenase in Maternal Arteries

Objective: Preeclampsia is a pregnancy-associated disorder that is characterized by elevated maternal blood pressure, end organ damage, and/or proteinuria. This pregnancy syndrome affects 2-8% of pregnancies worldwide and has no treatment other than fetal delivery. The mechanisms behind the development of this condition remain unknown and is one of the barriers preventing the development of effective treatment. One of the suggested etiologies behind preeclampsia is activation of the innate immune system. We have previously determined that maternal exposure to CpG DNA (a ligand of Toll-like Receptor-9, TLR-9) causes maternal hypertension and excess vasoconstriction. In cancer cells, CpG DNA/TLR-9 activation leads to upregulation of cyclooxygenase (COX), which is the rate-limiting step in the conversion of arachidonic acid to prostaglandins and thromboxanes. It is unknown whether treatment with CpG DNA during pregnancy affects COX in maternal and fetal tissues. Hypothesis: Treatment of pregnant rats with CpG DNA induces maternal hypertension and increases COX function in maternal and fetal tissues. Methods: Pregnant Sprague-Dawley rats were treated with ODN 2395 (synthetic CpG DNA, 100μg/rat/ i.p. injection) and saline (control group) on gestational days (GD): 14, 16, 18 (term: 21-22 days). Tail cuff blood pressure was measured on GD19. On GD20, rats were euthanatized and maternal liver and arteries as well as fetal tissues were frozen for western blot analysis. Thromboxane B2 (TxB2) was measured in serum and media from maternal arteries by ELISA. Results: ODN 2395 increased systolic BP (Control: 100±4 mmHg vs. ODN2395 119±4 mmHg, p=0.006). Serum TxB2 was greater in the ODN 2395 group compared to control rats (Control: 65.2±8.9 ng/mL vs. ODN2395: 123.6±19.7 ng/mL, p=0.03). ODN2395 also increased release of TxB2 from mesenteric (Control: 28.2±4.3 pg/mg tissue vs ODN 54.5±6.2 pg/mg tissue, p=0.008) but not from uterine arteries (p>0.05). Western Blot analysis revealed greater expression of COX-2 in mesenteric (p=0.002) and uterine arteries (p=0.006) in ODN2395-treated animals. ODN2395 increased COX-1 expression in mesenteric arteries (p=0.006) and showed a moderate effect on uterine arteries (p=0.07). No differences were observed between treatment groups for COX-1 and COX-2 in maternal (p>0.07) and fetal liver (p>0.20). Conclusions: Exposure to CpG DNA during pregnancy induced maternal hypertension and augmented function of COX in maternal arteries.