Rationale Sympathetic nervous system control of inflammation plays a central role in hypertension. The gut receives significant sympathetic innervation, is densely populated with a diverse microbial ecosystem, and contains immune cells that greatly impact overall inflammatory homeostasis. Despite this uniqueness, little is known about the involvement of the gut in hypertension. Objective Test the hypothesis that increased sympathetic drive to the gut is associated with increased gut wall permeability, increased inflammatory status, and microbial dysbiosis and that these gut pathological changes are linked to hypertension. Methods and Results Gut epithelial integrity and wall pathology were examined in spontaneously hypertensive rat (SHR) and chronic Angiotensin II infusion rat models. The increase in blood pressure in SHR was associated with gut pathology that included increased intestinal permeability and decreased tight junction proteins. These changes in gut pathology in hypertension were associated with alterations in microbial communities relevant in blood pressure control. We also observed enhanced gut-neuronal communication in hypertension originating from paraventricular nucleus of the hypothalamus and presenting as increased sympathetic drive to the gut. Finally, angiotensin converting enzyme inhibition (captopril) normalized blood pressure and was associated with reversal of gut pathology. Conclusions A dysfunctional sympathetic-gut communication is associated with gut pathology, dysbiosis, and inflammation, and plays a key role in hypertension. Thus, targeting of gut microbiota by innovative probiotics, antibiotics, and fecal transplant, in combination with current pharmacotherapy, may be a novel strategy for hypertension treatment.

Rationale : Studies have demonstrated that angiotensin-converting enzyme 2 (ACE2) plays a protective role against lung diseases, including pulmonary hypertension (PH). Recently, an antitrypanosomal drug, diminazene aceturate (DIZE), was shown to exert an "offtarget" effect of enhancing the enzymatic activity of ACE2 in vitro. Objectives: To evaluate the pharmacological actions of DIZE in experimental models of PH. Methods: PH was induced in male Sprague Dawley rats by monocrotaline, hypoxia, or bleomycin challenge. Subsets of animals were simultaneously treated with DIZE. In a separate set of experiments, DIZE was administered after 3 weeks of PH induction to determine whether the drug could reverse PH. Measurements and Main Results: DIZE treatment significantly prevented the development of PH in all of the animal models studied. The protective effects were associated with an increase in the vasoprotective axis of the lung renin-angiotensin system, decreased inflammatory cytokines, improved pulmonary vasoreactivity, and enhanced cardiac function. These beneficial effects were abolished by C-16, an ACE2 inhibitor. Initiation of DIZE treatment after the induction of PH arrested disease progression. Endothelial dysfunction represents a hallmark of PH pathophysiology, and growing evidence suggests that bone marrow-derived angiogenic progenitor cells contribute to endothelial homeostasis. We observed that angiogenic progenitor cells derived from the bone marrow of monocrotaline-challenged rats were dysfunctional and were repaired by DIZE treatment. Likewise, angiogenic progenitor cells isolated from patients with PH exhibited diminished migratory capacity toward the key chemoattractant stromal-derived factor 1a, which was corrected by in vitro DIZE treatment. Conclusions: Our results identify a therapeutic potential of DIZE in PH therapy.Keywords: pulmonary hypertension; ACE2; angiogenic progenitor cells; diminazene Pulmonary hypertension (PH) is a life-threatening disease characterized by elevated pressure in the pulmonary arteries and What This Study Adds to the FieldWe show that diminazene, an antitrypanosomal drug, attenuates hemodynamic changes, prevents maladaptive right ventricular remodeling, and enhances pulmonary vasorelaxation in experimental models of PH through activation of ACE2. Furthermore, diminazene improves the functions of APCs obtained from experimental animals and patients with PH. This study identifies a new application for an existing drug, which could be successfully developed for PH therapeutics.

Angiotensin-converting enzyme 2 (ACE2) plays a critical role against myocardial infarction (MI). We hypothesized that activation of intrinsic ACE2 would be protective against ischemia-induced cardiac pathophysiology. Diminazine aceturate (DIZE), a small molecule ACE2 activator has been used to evaluate this hypothesis. DIZE (15 mg/kg/day, s.c.) was injected two days prior to MI surgery and continued throughout the study-period. MI rats showed a 62% decrease in fractional shortening (FS,%) [control (Con): 51.1 ± 3.2; DIZE alone (D) : 52.1 ± 3.2; MI (M): 19.1± 3.0], a 55% decrease in contractility (dP/dtmax mmHg/s) (Con: 9480 ± 425.3; D: 9585 ± 597.4; M: 4251 ± 657.7), and a 27% increase in ventricular hypertrophy [VH, mg/mm (Con: 26.5 ± 1.5; D: 26.9 ± 1.4; M: 33.4± 1.1)]. DIZE attenuated the MI-induced decrease in FS by 89%, improved dP/dtmax by 92%, and reversed VH by 18%. MI also significantly increased ACE and angiotensin type 1 receptor levels while decreased ACE2 activity by 40% (Con: 246.2 ± 25.1; D: 254.2 ± 20.6; M: 148.9 ± 29.2, RFU/min), which was reversed by DIZE treatment. Thus, DIZE treatment decreased the infarct area, attenuated LV remodeling post-MI and restored normal balance of the cardiac renin angiotensin system. Additionally, DIZE treatment increased circulating endothelial progenitor cells, increased engraftment of cardiac progenitor cells and decreased inflammatory cells in peri-infarct cardiac regions. All of the beneficial effects associated with DIZE treatment were abolished by C-16, an ACE2 inhibitor. Collectively, DIZE and DIZE-like small molecules may represent promising new therapeutic agents for MI.

Pulmonary arterial hypertension (PAH) is a chronic lung disease with poor diagnosis and limited therapeutic options. The current available therapies are ineffective in improving the quality of life and reducing mortality rates. There exists a clear unmet medical need to treat this disease, which necessitates the discovery of novel therapeutic targets/agents for safe and successful therapy. An altered renin-angiotensin system (RAS) has been implicated as a causative factor in the pathogenesis of PAH. Angiotensin II, a key effector peptide of the RAS, can exert deleterious effects on the pulmonary vasculature resulting in vasoconstriction, proliferation and inflammation, all of which contribute to PAH development. Recently, a new member of the RAS, Angiotensin converting enzyme 2 (ACE2), was discovered. This enzyme functions as a negative regulator of the angiotensin system by metabolizing Angiotensin II to a putative protective peptide, Angiotensin-(1-7). ACE2 is abundantly expressed in the lung tissue and emerging evidence suggests a beneficial role for this enzyme against lung diseases. In this review, we focus on ACE2 in relation to pulmonary hypertension and provide proof of principle for its therapeutic role in PAH.