Circulating angiotensin II type I receptor – autoantibodies in diabetic pregnancies

Pregnant women with either pre-existing or gestational diabetes mellitus are at increased risk of preeclampsia as well as future cardiovascular disease. The renin-angiotensin system is dysregulated in both diabetes mellitus and preeclampsia. In preeclampsia, maternal levels of circulating agonistic autoantibodies against the angiotensin II Type I receptor (AT1-AAs) are increased. Circulating AT1-AAs are thought to contribute to both the pathophysiology of preeclampsia and the increased risk of future cardiovascular disease. Studies exploring AT1-AA in diabetes outside pregnancy suggest their potential for both metabolic and cardiovascular pathogenicity. No studies have investigated AT1-AAs in diabetic pregnancies. We hypothesized elevated maternal circulating AT1-AA levels in pregnancies complicated by any type of diabetes mellitus. Third-trimester maternal serum from 39 women (controls: n= 10; type 1 diabetes: n= 9; type 2 diabetes: n=10; gestational diabetes=10) were analyzed for AT1-AA using an established bioassay method. Circulating AT1-AAs were present in 70% (7/10) of the controls and 83% (24/29) of the diabetes group (P=0.399). Presence of AT1-AA was correlated to hsCRP levels (P=0.036), but neither with maternal circulating angiogenic factors (soluble fms-like tyrosine kinase-1 and placental growth factor), nor with maternal or fetal characteristics indicative of metabolic disease or placental dysfunction. Our study is the first to demonstrate presence of circulating AT1-AAs in pregnant women with any type of diabetes. Our findings suggest AT1-AAs presence in pregnancy independently of placental dysfunction, nuancing the current view on their pathogenicity. Whether AT1-AAs per se contribute to increased risk of adverse pregnancy outcomes and future cardiovascular disease remains currently unanswered.