Abstract 069: Isoketals in Monocyte-Derived Dendritic Cells Activate T Cells and Promote Hypertension
Fatty acid oxidation leads to formation of highly reactive γ-ketoaldehydes termed isoketals that adduct to protein lysines. We have shown that hypertension causes isoketals to accumulate in dendritic cells (DCs) and activate T cells. Human monocytes traversing the endothelium differentiate into DCs expressing CD83, MHC-II, and CD11c. We hypothesized that oxidative stress catalyzes the formation of isoketals which alters monocyte and DC function to promote monocyte transformation to DCs and T cell activation. Thus, we co-cultured human monocytes with aortic endothelial cells exposed to either a hypertensive 10% stretch or a normotensive 5% stretch for 48 hours using the Uniflex® culture system. We used flow cytometry to detect human DC markers (CD14-/CD83+) in monocytes exposed to stretch. We detected conversion of CD14-/CD83+ from CD14+ human monocytes and found they contained increased levels of isoketal-ligated proteins in the 10% compared to 5% stretch (77.47 ± 7.3 vs. 12.14 ± 3.5). We also found a 1.8 fold increase of the CD86 activation marker compared to controls. Exposure of murine monocyte-derived DCs to tert-butyl hydroperoxide (t-BHP) led to a 3-fold increase in isoketals and a 2-fold increase in CD86 in the CD11b+/CD11c+ population compared to controls. Isoketal formation in DCs exposed to t-BHP was scavenged with pre-treatment of 2-hydroxybenzylamine (2-HOBA) in vitro. DCs treated with t-BHP were co-cultured with T cells for 7 days. This promoted T cell survival and proliferation of CD8+ and CD4+ T cells compared to untreated controls; this effect was attenuated with pre-treatment of 2-HOBA. Moreover, adoptive transfer of t-BHP treated DCs to normal mice elevated the hypertensive response to a generally subpressor dose of angiotensin-II (128 ± 0.80 vs. 114 ± 0.48 in controls). We conclude that oxidant stress and isoketal formation in murine DCs promote T cell activation and hypertension. We hypothesize that exposure to hypertensive stretch in human endothelial cells transfers an oxidant signal to monocytes and promotes their transformation to DCs, which mature and promote an immune response. These findings provide a mechanism as to how T cells are activated in hypertension and provide insight into the inflammatory nature of this disease.
Author Disclosures: R. Loperena: None. A. Kirabo: None. S.S. Davies: None. L. Roberts: None. D.G. Harrison: None.
- © 2014 by American Heart Association, Inc.