24: NK cell-mediated mitochondrial oxidative stress and hypertension in response to CD4+T cells from RUPP rats

Abstract

Preeclampsia (PE) is new onset hypertension associated with activated CD4+T cells, NK cells, and cytokines during pregnancy. We have previously shown that women with PE exhibit placental mitochondrial (mt) dysfunction and ROS compared to normal pregnant (NP) women. The Reduced Uterine Perfusion Pressure (RUPP) rat model produces many characteristics of PE including hypertension, increases in CD4+T cells and renal/placental NK cells, and mt ROS and dysfunction. We have previously demonstrated that RUPP CD4+T cells cause hypertension in NP rats, however the role of RUPP CD4+T cells in stimulating NK cells to cause mt dysfunction and ROS remains unclear. Therefore, we examined the effect of adoptive transfer of RUPP CD4+T cells to activate NK cells in NP rats. Splenic CD4+T cells were isolated from RUPP rats, cultured, and injected into NP rats on gestation day 13. On gestation day 19, MAP and tissue samples were collected, mt respiration and ROS were measured in isolated mitochondria using the Oxygraph 2K and fluorescent microplate reader, and results were compared with a student’s t-test. MAP increased to 110±2 in NP + RUPP CD4+T cells (n=12) compared to 101±2 mmHg in NP controls (n=7, p< 0.05). Circulating cytolytic NK cells increased to 3±0.6% in recipients of RUPP CD4+T cells (n=8) compared to 0.3±0.2% in NP (n=7, p< 0.05). Renal state 3 (231.9±127.7 vs 814.1±291.6 pmol/sec/mg, p=0.17) and maximal (213.3±117 vs 422.3±89.5 pmol/sec/mg, p=0.21) respiration rates, indicative of ATP production and mt efficacy, were reduced in NP+RUPP CD4+T cells (n=3) compared to NP (n=5). Renal mtROS increased from 249.2±45.6% in NP to 597.1±155.4% in NP+RUPP CD4+T cells (p< 0.05). These data indicate that CD4+T cells stimulated in response to placental ischemia activates NK cells and causes renal mt dysfunction in association with ROS and hypertension during pregnancy, all of which are important mechanisms in the pathophysiology of PE.