Abstract 354: Mechanical Stretch on Endothelial Cells Promotes Monocyte Differentiation into Immunogenic Dendritic Cells

Abstract

Fatty acid oxidation leads to formation of highly reactive isoketals that adduct to protein lysines. We have shown that dendritic cells (DCs) from hypertensive mice accumulate isoketal-adducted proteins and promote T cell activation. In hypertension, the endothelium is activated to produce reactive oxygen species and to express adhesion molecules and chemokines that attract inflammatory cells. Human monocytes that traverse the endothelium differentiate into monocyte-derived DCs upon exposure to a pro-inflammatory state. We hypothesized that human endothelial cells exposed to mechanical stretch promote conversion of human monocytes into immunogenic DCs. We co-cultured human aortic endothelial cells (HAECs) with monocytes from normotensive human donors and exposed the HAEC monolayer to either normal cyclical stretch (5%) or hypertensive cyclical stretch (10%) using the Flexcell ® Tension System for 48 hours. We found that co-culture of monocytes with HAECs exposed to 10% mechanical stretch markedly increased monocyte mRNA expression of the Th17 polarizing cytokines IL-6, I-23A and IL-1β and monocyte chemokine CCL4 and the p22 phox subunit of the NADPH oxidase compared to 5% stretch. HAECs exposed to 10% stretch promoted monocyte in culture to differentiate into DCs, as evidenced by the surface expression of DC-SIGN, CD83 and the co-stimulatory marker CD86. These monocytes also had an accumulation of isoketal-adducted proteins compared to controls (69.73 ± 5.802 vs 10.79 ± 1.854 respectively, p = 0.0001) as evidenced by intracellular staining and flow cytometry. Monocytes co-cultured with 10%-stretched HAECs induced a 1,500-fold increase in CD4 + T cell proliferation and a 1,300-fold increase in CD8 + T cells proliferation as monitored by CFSE compared to 5% stretch controls. Conversely, monocytes-HAEC cultures exposed to 10% stretch and treated with STAT3 inhibitor, stattic, prevented both CD4 + and CD8 + T cell proliferation. These data show that endothelial cells exposed to mechanical stretch cross-talk with monocytes to promote their differentiation into immunogenic DCs potentially via the JAK/STAT3 pathway. These findings give insight into a new mechanism of lymphocyte activation in the vascular endothelium during hypertension.