Project description:Non-enzymatic activation of renin via its interaction with prorenin receptor (PRR) has been proposed as a key mechanism of local renin-angiotensin system (RAS) activation. The presence of renin and angiotensinogen has been reported in the rostral ventrolateral nucleus (RVLM). Overactivation of bulbospinal neurons RVLM is linked to hypertension (HTN). Previous studies have shown that the brain RAS plays a role in the pathogenesis of the deoxycorticosterone (DOCA)-salt HTN model. Thus, we hypothesized that PRR in the RVLM is involved in the local activation of the RAS, facilitating the development of DOCA-salt HTN. Selective PRR ablation targeting the RVLM (PRRRVLM-Null mice) resulted in an unexpected sex-dependent and biphasic phenotype in DOCA-salt HTN. That is, PRRRVLM-Null females (but not males) exhibited a significant delay in achieving maximal pressor responses during the initial stage of DOCA-salt HTN. Female PRRRVLM-Null subsequently showed exacerbated DOCA-salt-induced pressor responses during the “maintenance” phase with a maximal peak at 13 days on DOCA-salt. This exacerbated response was associated with an increased sympathetic drive to the resistance arterioles and the kidney, exacerbated fluid and sodium intake and output in response to DOCA-salt, and induced mobilization of fluids from the intracellular to extracellular space concomitant with elevated vasopressin. Ablation of PRR suppressed genes involved in RAS activation and catecholamine synthesis in the RVLM but also induced expression of genes involved in inflammatory responses. This study illustrates complex and sex-dependent roles of PRR in the neural control of BP and hydromineral balance through autonomic and neuroendocrine systems.
Project description:In the present study we made use of the (1-renin) DOCA-salt mouse model - which has been previously shown to develop cardiac and renal hypertrophy - to evaluate the direct effects of high-salt diet on cardiac function and gene expression profiling. The comparison between low-salt and high-salt DOCA-treated mice will reveal what genes are directly modulated by sodium in (normotensive) DOCA-treated mice. Previous publications: Wang Q, Hummler E, Nussberger J, Clement S, Gabbiani G, Brunner HR, Burnier M. Blood pressure, cardiac, and renal responses to salt and deoxycorticosterone acetate in mice: role of renin genes. J Am Soc Nephrol. 2002;13:1509 –1516. Wang Q, Domenighetti AA, Pedrazzini T, Burnier M. Potassium supplementation reduces cardiac and renal hypertrophy independent of blood pressure in DOCA/salt mice. Hypertension. 2005 Sep;46(3):547-54. Keywords: comparative dose-response treatment (2 groups)
Project description:We assigned carboxypeptidase X 2 (Cpxm2) to a genetic locus for left ventricular mass. The functional role of Cpxm2 was investigated in Cpxm2-deficient (KO) and wild-type (WT) mice exposed to deoxycorticosterone acetate (DOCA)-salt hypertension and control conditions (SHAM). Both WT and KO animals developed severe and similar systolic hypertension in response to DOCA. WT mice developed severe LV damage. These changes were significantly ameliorated or even normalized (i.e. ejection fraction) in KO-DOCA animals. LV transcriptome analysis in WT, but not in KO mice, showed a molecular cardiac hypertrophy/remodeling signature with significant upregulation of 1234 transcripts including Cpxm2 in response to DOCA.
Project description:Background: Neuron-expressing ADAM17 (a disintegrin and metalloprotease 17) has been shown to support sympatho-excitation and salt-sensitive hypertension. The aim of current work was to identify by what mechanism ADAM17 in glutamatergic neurons support activation of presympathetic neurons (PSN). Methods: Both acute Ang-II stimulation in the PVN (paraventricular nucleus) and DOCA (deoxycorticosterone acetate)-salt model were utilized for electrophysiological recording and blood pressure (BP) recording, in mice with ADAM17 selective knockout in glutamatergic neurons (A17G), and ADAM17 targeted knockout in certain glutamatergic PVN-RVLM (rostral ventrolateral medulla) projecting neurons (PSN-A17G). Results: Both Ang-II and DOCA-salt treatment markedly decreased GABAergic inhibitory tone in the PVN of WT (wild-type) mice. Post DOCA-salt treatment, microglia were activated in the PVN, with significantly more expression of CD68 and related cytokines. With 7-day of DOCA-salt treatment, before BP arrived its plateau, PVN microglia had already been activated, and they were spotted more closely to virus-labeled glutamatergic PSN. Moreover, the number of GABAergic presynaptic terminals, locating on the soma area of PSN, was markedly reduced. In both A17G and PSN-A17G, these DOCA-salt-associated changes were blunted. Further experiments revealed that Ang-II promotes neuron-mediated chemotaxis for microglia, and this effect in neurons involved ADAM17 and its downstream – CX3CL1/CX3CR1 chemotactic pathway. Pharmacologically blocking CX3CR, or inhibiting migration of microglia, confirmed the contribution of CX3CL1/CX3CR1 signaling pathway and microglial displacement to Ang-II-induced disinhibition and activation of PSN.
Project description:We compared the transcriptomic changes in cell populations of the arcuate nucleus of the hypothalamus in 21 day treated DOCA-salt male mice versus sham male mice using high-throughput single-nucleus RNA-seq.
Project description:Heart failure with preserved ejection fraction (HFpEF) is characterized by diastolic dysfunction, microvascular dysfunction and myocardial fibrosis with recent evidence implicating the immune system in orchestrating cardiac remodeling. Here, we show the mouse model of deoxycorticosterone acetate (DOCA)-salt hypertension induces key elements of HFpEF, including diastolic dysfunction, exercise intolerance, and pulmonary congestion in the setting of preserved ejection fraction. CITE-Seq analysis of cardiac immune cells reveals an altered abundance and/or transcriptional signature in multiple cell types, most notably cardiac macrophages. The DOCA-salt model results in differential expression of several known and novel genes in cardiac macrophages, including upregulation of Trem2, which was also recently implicated in obesity and atherosclerosis. The role of macrophage Trem2 in cardiac remodeling, however, is unknown. We found that mice with genetic deletion of Trem2 exhibit increased cardiac hypertrophy and decreased cardiac capillary density after DOCA-salt treatment compared to wild-type controls, and Trem2-deficient macrophages have impaired expression of pro-angiogenic gene programs. Furthermore, we found that plasma levels of soluble TREM2 are elevated in human heart failure. Together, our data suggest a novel cardioprotective role for macrophage Trem2 in cardiac remodeling and heart failure and provide an atlas for the identification of additional targets that can lead to improved diagnostic and therapeutic strategies for HFpEF.
Project description:Hypertension (HTN) has been associated with cerebrovascular dysfunction and cognitive impairment. To understand how HTN affects the brain, the coupling between oxygen consumption and cerebral blood flow in multiple brain regions was firstly analyzed using functional MRI, in patients with HTN and healthy controls. It indicated less functional hyperemia in the cortical areas of HTN group, but showed no difference in their hippocampus. We then used deoxycorticosterone acetate (DOCA)-salt model, in which HTN is developed via sympathetic overactivity, and confirmed HTN-associated cognitive decline and reduction in functional hyperemia of pia arterioles in both male and female mice. Notably, maze test-based cognitive function was partially protected in female mice. In the sensory cortex and hippocampus of male HTN mice, we detected higher reactiveness of glial cells, compared to sham controls. But microglia in the hippocampus reacted more to DOCA-salt, showing a sub-population characterized by high expression of Apoe, B2m, Ramp1, and S100a8/a9, which was not detected in the cortex. With further analyzing the gene profile of immune cells, it revealed disease-associated types of monocyte and macrophage only in the hippocampus, and pinpointed an involvement of peripheral reservoir of immune cells. Next, to determine possible contribution from sympathetic agitation of the peripheral immune system, we tested mice lacking neuron-expressed type 1 angiotensin-II receptors (AT1R), a line that previously showed blunted sympathoexcitation under DOCA-salt treatment. In addition to improved cognitive function, DOCA-salt-induced upregulation of glial reactiveness and pro-inflammatory markers were not seen, and Bdnf expression was preserved in the hippocampus of those mice. To test the role of spleen, which deployed leukocytes upon splenic sympathoexcitation in DOCA-salt HTN, splenectomy was performed and it attenuated hippocampal inflammation and cognitive impairment, in a similar manner as neuronal AT1R knockout. Together, our data provide evidence that the cortex and hippocampus were differently affected by HTN, and proposed a neural mechanism for HTN-associated cognitive impairment that involves sympathoexcitation-induced immune response, thus highlighting that autonomic regulation of the immune system could be a therapeutic target for improving hippocampal health during HTN.
Project description:We report the transcriptomic analysis of RNA-seq of abdominal aortas isolated from WT and PSGL-1-/- mice exposed to deoxycorticosterone acetate (DOCA) plus salt to uncover the mechanisms underlying the undefined role of PSGL-1 in abdominal aortic aneurysm (AAA)