RNA interference therapeutics targeting angiotensinogen ameliorate preeclamptic phenotype in rodent models.

Introduction As one of the leading causes of maternal mortality worldwide, hypertensive disorders of pregnancy remain inadequately treated (1). Preeclampsia, a subset of such disorders, occurs in 5% to 8% of pregnancies, threatening to continue to fulminant eclampsia (1). Preeclampsia is characterized by new-onset maternal hypertension (>140/90 mmHg) after the 20th week of gestation accompanied by proteinuria (>300 mg/L protein in a 24-hour urine collection) or in association with thrombocytopenia, impaired liver function, development of renal insufficiency, pulmonary edema, or new-onset cerebral or visual disturbances (2). Furthermore, it is associated with negative fetal consequences, with fetal growth restriction (FGR) a common outcome. Newborns with FGR have structural and metabolic abnormalities that compromise their development (3). Moreover, preeclampsia is associated with increased long-term cardiovascular risk for both the mother and the child (3, 4). Preeclampsia is distinct in its complex pathophysiology, and the molecular mechanisms are not understood. Poor placentation, as well as maternal risk factors leading to placental dysfunction, is involved in the pathogenesis (1). Many factors have been identified as having an involvement in the progression of preeclampsia, including dysfunction of the renin-angiotensin system (RAS) (5). As the primary effector of the RAS, angiotensin II is a peptide hormone with vasoconstrictive and inflammatory properties, and forms a major component of blood pressure homeostasis (6). Angiotensin II is produced by […] hallmark features of new-onset hypertension and proteinuria after 20 weeks of gestation, is a major cause of fetal and maternal morbidity and mortality. Studies have demonstrated a role for the renin-angiotensin system (RAS) in its pathogenesis; however, small-molecule RAS blockers are contraindicated because of fetal toxicity. We evaluated whether siRNA targeting maternal hepatic angiotensinogen ( Agt ) could ameliorate symptoms of preeclampsia without adverse placental or fetal effects in 2 rodent models. The first model used a cross of females expressing human Agt with males expressing human renin, resulting in upregulation of the circulating and uteroplacental RAS. The second model induced ischemia/reperfusion injury and subsequent local and systemic inflammation by surgically reducing placental blood flow mid-gestation (reduced uterine perfusion pressure [RUPP]). These models featured hypertension, proteinuria, and fetal growth restriction, with altered biomarkers. siRNA treatment ameliorated the preeclamptic phenotype in both models, reduced blood pressure, and improved intrauterine growth restriction, with no observed deleterious effects on the fetus. Treatment also improved the angiogenic balance and proteinuria in the transgenic model, and it reduced angiotensin receptor activating antibodies in both. Thus, an RNAi therapeutic targeting Agt ameliorated the clinical sequelae and improved fetal outcomes in 2 rodent models of preeclampsia. levels of hAGT-targeting siRNA were quantified stem loop quantitative reverse transcriptase PCR (qRT-PCR). (fro-zen, powderized) were reconstituted to 100 mg/mL 0.25% Triton X-100 and lysed by Further dilution of samples on a naive background matrix was made when the concentration of the siRNA might be expected to exceed the upper limit of quantification. The obtained supernatant subsequently was used to generate antisense-specific cDNA using a sequence-specific stem loop cDNA primer (GTCGTATCCAGTG-CAGGGTCCGAGGTATTCGCACTGGATACGACtgagaa). using assay