Abstract 034: ROCK2 Specific Inhibition Decreases Th17/Treg Balance And Reduces DOCA-salt Hypertension-associated End-Organ Damage

Abstract

Hypertension is characterized by immune activation and inflammatory end-organ damage, yet there are no therapies for hypertension that specifically target the immune system. We previously demonstrated a critical role for pro-inflammatory CD4+ T cell derived cytokines, interleukin 17A (IL-17A) and IL-21, in the full development of hypertension and hypertension-associated renal and vascular damage. Rho-associated coiled-coil containing protein kinase 2 (ROCK2) has been shown to function as a molecular switch upregulating Th17 and inhibiting anti-inflammatory regulatory T cell (Treg) differentiation in autoimmune diseases. We found that ROCK2 expression is upregulated in splenic and renal CD4+ T cells in a DOCA (deoxycorticosterone acetate)-salt model of hypertension. We hypothesized that hypertensive stimuli increase T cell ROCK2 activity, leading to increased Th17/Treg ratios, and that selective ROCK2 inhibition is a potential novel therapeutic target for hypertension-associated end-organ damage. We showed in vitro that KD025, an orally bioavailable ROCK2 inhibitor, inhibits Th17 proliferation and IL-17A/IL-21 production. We then tested ROCK2 inhibition in vivo where DOCA salt-induced hypertension (uninephrectomy + 100mg DOCA pellet + 1% NaCl drinking water) was initiated in all mice allowing for hypertension to develop for 10 days, followed by treatment with KD025 (50mg/kg daily, n=11) or vehicle (n=8) starting on day 11 through the remainder of the protocol. KD025 treatment significantly attenuated cardiac hypertrophy (8.7±0.3 vs 7.6±0.2 mg/grams body weight, p=0.005) and left ventricular (LV) fibrosis (4.9±1.7 vs 2.4±1.3% LV area, p=0.008). Flow cytometric analysis revealed that KD025 decreased F4/80+ infiltrating cardiac macrophages (24,000±578 vs 18,918±1,430 cells, p=0.011) and decreased the Th17/Treg ratio (0.251±0.041 vs 0.117±0.009, p=0.003) in the heart. Furthermore, KD025 attenuated renal infiltration of CD3+ T cells (59.0±5.6 vs 43.5±3.8 cells/mg tissue, p=0.019) and albuminuria (163.4±24.1 vs 103.1±21.9 ug albumin/mg creatinine, p=0.011). These data indicate that the ROCK2-specific inhibitor KD025 may be a novel therapeutic for the treatment of hypertension and the associated end-organ damage.