Abstract 044: Deletion of Serum and Glucocorticoid-regulated Kinase 1 (SGK1) in T Cells Attenuates Hypertension and Renal/Vascular Dysfunction

Abstract

We have previously shown that the T cell-derived pro-inflammatory cytokine, interleukin 17A (IL17A), is upregulated by and promotes angiotensin II (Ang II)-induced hypertension and contributes to renal and vascular dysfunction. It was recently demonstrated that an excess of 40 mM of sodium chloride enhances IL17A production from CD4+ T cells in an SGK1 dependent manner. Since dietary salt intake is associated with hypertension, we hypothesized that T cell SGK1 promotes hypertension and contributes to end-organ dysfunction. To test this hypothesis, we crossed SGK1 fl/fl mice with Tg CD4cre mice to delete SGK1 in T lymphocytes. Loss of T cell SGK1 resulted in a blunted blood pressure response following 2 weeks of Ang II infusion (24.8 mmHg reduction, p=0.01). Moreover, renal and vascular inflammation in response to Ang II infusion was abrogated in these mice compared to SGK1 fl/fl control mice. Ang II infusion increased total (CD45+) leukocytes in the kidney from 55.4 to 120.4 x10 3 (p<0.01) in SGK1 fl/fl mice while there was no increase in mice with T cell deletion of SGK1 (48.1 to 47.5x10 3 , p=ns). Similarly, Ang II increased total (CD45+) leukocytes in the aorta from 5.7 to 52.4x10 3 (p<0.01) in SGK1 fl/fl mice compared to no increase in mice with T cell deletion of SGK1 (16.1 to 10.1x10 3 , p=ns). Furthermore, relaxation of mesenteric arterioles isolated from Ang II infused SGK1 fl/fl mice in response to acetylcholine was impaired by 22.37% (p<0.0001) compared to a 2.62% (p=ns) impairment in vessels isolated from mice with T cell deletion of SGK1, demonstrating that the latter group has preserved endothelial function despite Ang II infusion. To assess renal dysfunction, we measured urinary albumin:creatinine ratio which increased 5.81-fold (p<0.01) in SGK1 fl/fl mice infused with Ang II compared to 3.23-fold (p=ns) in mice without T cell SGK1, demonstrating that these mice are protected from Ang II-induced renal injury. Finally, we found that total numbers of splenic CD4+IL17A+ cells increase from 0.44% to 1.15% (p<0.05) in SGK1 fl/fl mice infused with Ang II compared to no change (0.45% to 0.47%, p=ns) in mice without T cell SGK1. These studies demonstrate that T cell SGK1 may be a novel therapeutic target for hypertension and the associated end-organ dysfunction.