Abstract P120: Leukocyte and Lymphocyte-Derived Extracellular Vesicles are Elevated in Angiotensin-Induced Hypertension

Abstract

Infiltration of macrophages and T cells in kidneys and vasculature may play a role in the development of hypertension (HTN) and extracellular vesicles (EVs) have emerged as novel cell-to-cell communicators in the pathogenesis HTN. Immune cell-derived EVs can reflect the pathophysiological activity of the parental cell and mediate immune stimulation or inhibition in paracrine fashion. We investigated subgroups of circulating leukocyte-derived EVs (LEVs) in angiotensin II (Ang II)-induced HTN with or without candesartan (C) or hydralazine, hydrochlorothiazide, and reserpine (HHR). Ang II was delivered via osmotic mini pumps (500 ng/kg/min; n=15) and with C (10 mg/kg/day, n=5) or HHR (30 mg/kg/day, n=5) in drinking water for 4 weeks to 129S6 mice. Systolic blood pressure (SBP) was measured daily by tail-cuff manometry. After 4 weeks, mice were euthanized and citrated blood collected. EV isolation was performed by differential centrifugation, followed by EV phenotyping with imaging flow cytometry. We used EV surface markers for leukocyte (CD45), T- and B-cells (CD3,CD19), neutrophils (Ly6g+/CD11b-) and monocytes/macrophages (Ly6g-/CD11b+). Ang II infused mice had significantly higher SBP compared to normotensive controls (NC) (n=5) (173.79 ± 4.9mmHg vs 129.8 ± 6.2mmHg, p <0.0001) and C/HHR treated mice (134.42 ± 7.5mmHg (C) and 138.21 ± 5.2mmHg (HHR), p = NS). Leukocyte-derived EV counts (CD45+ EVs for Ang II: 2.16E+06 particles/ml; NC: 6.15E+05 particles/mL; p=0.0001) and T cell-derived EV counts (CD3+) (Ang II: 2.14E+06 particles/ml, NC: 4.46E+05 particles/mL; p=0.0001] increased after 4 weeks in Ang II-infused mice compared to NC. In C and HHR treated groups, leukocyte- and T cell-derived EV concentrations were similar to NC, suggesting a BP effect rather than drug class effect. CD45+ and CD3+ EV concentrations correlated significantly with SBP [(r2=0.9343; p= 0.0004) and (r2= 0.8982; p= 0.0012), respectively]. In conclusion, leukocyte- and T cell-derived EVs were increased in Ang II-induced HTN and correlated significantly with SBP. Therefore, leukocyte- and T cell-derived EVs are potential bio-markers in HTN. Further studies are required to understand the functional role of leukocyte- and T cell-derived EVs in the pathogenesis of HTN.