The role of immune activation in contributing to vascular dysfunction and the pathophysiology of hypertension during preeclampsia

Abstract

Preeclampsia remains a leading cause of maternal death and perinatal morbidity and still the pathophysiological mechanisms of the disease remain largely unknown. The most well accepted hypothesis for the genesis of the disease is that placental ischemia/hypoxia results from inadequate remodeling of the maternal uterine spiral arteries, which leads to a decrease in uteroplacental blood flow. Subsequently factors are released from the ischemic placenta showering the maternal vascular endothelium. These factors include a host of molecules such as the soluble VEGF receptor-1 (sFlt-1), the angiotensin II type-1 receptor autoantibody (AT1-AA), and cytokines such as TNF-a and Interleukin 6 which in turn generate widespread dysfunction of the maternal vascular endothelium. This dysfunction results in elevated circulating endothelin (ET-1), reactive oxygen species (ROS), and augmented vascular sensitivity to angiotensin II as well as decreased formation of vasodilators such as nitric oxide and prostacyclin. These alterations in vascular function lead to hypertension with multi-organ dysfunction, especially in cases of early onset preeclampsia. Therefore, identifying the connection between placental ischemia and maternal cardiovascular abnormalities is an important area of investigation.

Figure 1. Potential role for immune activation in mediating the pathophysiology of hypertension during preeclampsia

Immunomodulators stimulated in response to placental ischemia play an important role in the generation of ROS, production of sFlt-1 and enhanced ET-1 and ANG II sensitivity thereby contributing to the development of hypertension during pregnancy