Effect of Hypertension of Dendritic Cell Gene Expression

Oxidative injury and inflammation have been implicated in the genesis of hypertension but the mechanisms involved are not fully understood. We describe a new pathway in which angiotensin II promotes dendritic cell (DC) activation of T cells and ultimately hypertension. NADPH oxidase-dependent superoxide production is increased 5-fold in DCs isolated from hypertensive mice as compared to sham-treated mice. This is associated with DC accumulation of protein-isoketal adducts and production of IL-6, IL-1β and IL-23. DCs from hypertensive mice but not sham mice promote survival and proliferation of CD8+ T cells in culture. Chemically diverse isoketal scavengers not only prevent activation and immunogenicity of DCs, but also attenuate angiotensin II-induced hypertension. Moreover, adaptive transfer of DCs from hypertensive mice prime development of hypertension in response to a subpressor dose of angiotensin II. Exposure of DCs to tert butyl hypdroperoxide promoted isoketal formation, DC stimulation of CD8+ T cell proliferation and primed hypertension in response to low dose angiotensin II. Serum isoprostanes, precursors to isoketals, were found to be elevated in humans with treated hypertension and were markedly elevated in patients with resistant hypertension. These studies show that angiotensin II-induced hypertension activates DCs, in large part by causing superoxide production and formation of isoketals. They define a new mechanism of hypertension and identify a potential new therapeutic approach for this disease. We used microarrays to detail the expression differences in dendritic cells under hypertensive conditions. Dendritic cells were isolated from mosue spleen and subsequently treated with Angiotensin II with or without co-treatment with 2-hydroxybenzylamine (2-HOBA) for RNA extraction and hybridization on Affymetrix microarrays. We sought to determine the effect of oxidative stress on dendritic cell expression profiles.