Abstract Fri032: T cell ROCK2 Promotes Hypertension-Associated Immune Activation and Cardiac Injury

Hypertension is the primary modifiable risk factor for cardiovascular disease, the number one cause of mortality worldwide. We previously demonstrated that Th17 activation and interleukin 17A (IL-17A) is integral for the full development of a hypertensive phenotype as well as the renal and vascular damage associated with hypertension. Rho-associated coiled-coil containing protein kinase 2 (ROCK2) serves as a molecular switch increasing Th17 and inhibiting regulatory T cell (Treg) differentiation of CD4+ T cells. We found that ROCK2 is upregulated in splenic CD4+ T cells in hypertensive mice, confirming the potential for influencing hypertension-associated T cell activation. We hypothesized that excessive T cell ROCK2 activation, leading to increased Th17/Treg ratios, contributes to hypertension and ultimately, end-organ damage. We first showed in vitro that KD025, an orally bioavailable ROCK2 inhibitor, inhibits Th17 proliferation and IL-17A production. We then tested the effect of ROCK2 inhibition in vivo on DOCA (deoxycorticosterone) salt-induced hypertension. DOCA-salt (uninephrectomy + 100mg DOCA pellet + 1% NaCl drinking water, n=19) was initiated in all mice allowing for hypertension to develop for 10 days, followed by treatment with the ROCK2 specific inhibitor KD025 (50mg/kg i.p. daily starting on Day 11, n=11) for the remainder of the 21-day protocol. KD025 treatment significantly attenuated cardiac hypertrophy and left ventricular fibrosis by the termination of the study. Furthermore, we observed a decrease in the Th17/Treg ratio in the heart by flow cytometry. Though KD025 is ROCK2-specific, this treatment was systemic and not limited to targeting ROCK2 in T cells. To verify that this protection is mediated through effects specifically on T cells, we obtained ROCK2 Fl/Fl mice and crossed this strain to mice expressing Cre recombinase driven by the CD4 promoter. We then subjected ROCK2 Fl/Fl CD4 Cre+ and ROCK2 Fl/Fl CD4 Cre- mice to the DOCA-salt protocol. We observed that Cre+ mice, lacking ROCK2 in T cells, exhibited an attenuation in the rise in blood pressure by Day 14 which was accompanied by reduced cardiac hypertrophy. These data indicate that the ROCK2 in T cells promotes a hypertensive state and the associated cardiac hypertrophy. Furthermore, the data show that the ROCK2-specific inhibitor KD025 may be a novel adjunct therapeutic treatment for hypertension and the associated tissue damage.