Angiotensin Type 1 Receptor Research Articles

Dopamine regulates adult neurogenesis in the ventricular-subventricular zone via dopamine D3 angiotensin type 2 receptor interactions.

Adult neurogenesis is a dynamic and highly regulated process, and different studies suggest that dopamine modulates ventricular-subventricular zone (V-SVZ) neurogenesis. However, the specific role of dopamine and the mechanisms/factors underlying its effects on physiological and pathological conditions such as Parkinson's disease (PD) are not fully understood. Recent studies have described counter-regulatory interactions between renin-angiotensin system (RAS) and dopamine in peripheral tissues and in the nigrostriatal system. We have previously demonstrated that angiotensin receptors regulate proliferation and generation of neuroblasts in the rodent V-SVZ. However, possible interactions between dopamine receptors and RAS in the V-SVZ and their role in alterations of neurogenesis in animal models of PD have not been investigated. In V-SVZ cultures, activation of dopamine receptors induced changes in the expression of angiotensin receptors. Moreover, dopamine, via D2-like receptors and particularly D3 receptors, increased generation of neurospheres derived from the V-SVZ and this effect was mediated by angiotensin type-2 (AT2) receptors. In rats, we observed a marked reduction in proliferation and generation of neuroblasts in the V-SVZ of dopamine-depleted animals, and inhibition of AT1 receptors or activation of AT2 receptors restored proliferation and generation of neuroblasts to control levels. Moreover, intrastriatal mesencephalic grafts partially restored proliferation and generation of neuroblasts observed in the V-SVZ of dopamine-depleted rats. Our data revealed that dopamine and angiotensin receptor interactions play a major role in the regulation of V-SVZ and suggest potential beneficial effects of RAS modulators on the regulation of adult V-SVZ neurogenesis.

Abstract 43: Non-Canonical AT1R/b-Arrestin2 Activation In Brain As A Regulator Of Fluid Homeostasis And Blood Pressure

The brain renin angiotensin system (RAS) is known for its role in cardiovascular and metabolic regulation. Angiotensin II (Ang II) is the major active product of the RAS, exerting most of its physiological effects through the angiotensin type-1 receptor (AT 1 R). Canonical or G-protein-mediated signaling of the AT 1 R within the brain has long been known to induce a dipsogenic and pressor response upon Ang II stimulation. Non-canonical or β-Arrestin mediated signaling is thought to counterbalance the detrimental effects of canonical signaling. However, the non-canonical AT 1 R/β-Arrestin pathway within the brain is understudied. Therefore, it is hypothesized that β-Arrestin activation contributes to fluid homeostasis and blood pressure (BP) regulation. Global β-Arrestin1 ( Arrb 1) and β-Arrestin2 ( Arrb 2) knockout (KO) mice were employed to evaluate drinking behavior and BP with and without deoxycorticosterone acetate (DOCA). Age- and sex-matched C57BL/6J mice served as controls. Mice were subjected to the two-bottle choice paradigm, in which the animals were presented with two bottles, one containing water and one containing 0.15M saline. In the absence of DOCA, mice lacking β-Arrestin2 had increased saline intake when compared to β-Arrestin1-KO and wildtype (WT=2.2±0.2 and Arrb 1-KO=2±0.4 vs Arrb 2-KO=5±0.7 mL/day; p<0.001; n=13, 11 and 9, respectively). This resulted in a saline preference, which means mice preferred saline over water by more than 50% by volume. In the presence of DOCA, mice lacking β-Arrestin2 had increased saline intake when compared to β-Arrestin1-KO and wildtype (WT=10.6±1.2 and Arrb 1-KO=6.5±0.8 vs Arrb 2-KO=16.6±2 mL/day; p<0.001; n=13, 11 and 9, respectively). However, these mice did not develop a saline preference. Preliminarily, β-Arrestin2-KO mice exhibited higher BP when compared to WT at baseline (WT=108±5 vs Arrb 2-KO=124±6 mmHg; n=2), which was exacerbated in response to DOCA (WT=122±6 vs Arrb 2-KO=140±5 mmHg; n=2). These findings suggest that β-Arrestin2 might counterbalance effects of canonical activation of the AT 1 R through G proteins. Overall, β-Arrestin2 appears to protect against cardiovascular diseases since the genetic ablation of β-Arrestin2 resulted in an increase in saline intake and exacerbated BP.

NADPH-Oxidase, Rho-Kinase and Autophagy Mediate the (Pro)renin-Induced Pro-Inflammatory Microglial Response and Enhancement of Dopaminergic Neuron Death.

Dysregulation of the tissue renin–angiotensin system (RAS) is involved in tissue oxidative and inflammatory responses. Among RAS components, renin, its precursor (pro)renin and its specific receptor (PRR) have been less investigated, particularly in the brain. We previously showed the presence of PRR in neurons and glial cells in the nigrostriatal system of rodents and primates, including humans. Now, we used rat and mouse models and cultures of BV2 and primary microglial cells to study the role of PRR in microglial pro-inflammatory responses. PRR was upregulated in the nigral region, particularly in microglia during the neuroinflammatory response. In the presence of the angiotensin type-1 receptor blocker losartan, to exclude angiotensin-related effects, treatment of microglial cells with (pro)renin induces the expression of microglial pro-inflammatory markers, which is mediated by upregulation of NADPH-oxidase and Rho-kinase activities, downregulation of autophagy and upregulation of inflammasome activity. Conditioned medium from (pro)renin-treated microglia increased dopaminergic cell death relative to medium from non-treated microglia. However, these effects were blocked by pre-treatment of microglia with the Rho-kinase inhibitor fasudil. Activation of microglial PRR enhances the microglial pro-inflammatory response and deleterious effects of microglia on dopaminergic cells, and microglial NADPH-oxidase, Rho-Kinase and autophagy are involved in this process.

Vitamin D suppresses bleomycin-induced pulmonary fibrosis by targeting the local renin\u2013angiotensin system in the lung

Idiopathic pulmonary fibrosis (IPF) is a severe disorder leading to progressive and irreversible loss of pulmonary function. In this study we investigated the anti-fibrotic effect of vitamin D using a mouse model of IPF. Lung fibrosis was induced with bleomycin in vitamin D-sufficient and vitamin D-deficient C57BL/6 mice. We found that treatment with active vitamin D analog paricalcitol prevented mouse body weight loss and alleviated lung fibrosis, whereas vitamin D deficiency severely aggravated lung injury. At the molecular level, paricalcitol treatment suppressed the induction of fibrotic inducer TGF-β and extracellular matrix proteins α-SMA, collagen type I and fibronectin in the lung, whereas vitamin D deficiency exacerbated the induction of these proteins. Interestingly, bleomycin treatment activated the local renin–angiotensin system (RAS) in the lung, manifested by the induction of renin, angiotensinogen, angiotensin II and angiotensin receptor type 1 (AT1R). Paricalcitol treatment suppressed the induction of these RAS components, whereas vitamin D deficiency enhanced the activation of the lung RAS. We also showed that treatment of bleomycin-induced vitamin D-deficient mice with AT1R antagonist losartan relieved weight loss, substantially ameliorated lung fibrosis and markedly blocked TGF-β induction in the lung. Moreover, we demonstrated that in lung fibroblast cultures, TGF-β and angiotensin II synergistically induced TGF-β, AT1R, α-SMA, collagen type I and fibronectin, whereas 1,25-dihydroxyvitamin D markedly suppressed the induction of these fibrotic markers. Collectively, these observations strongly suggest that vitamin D mitigates lung fibrosis by blocking the activation of the lung RAS in this mouse model of IPF.

Sympathetic modulation by antihypertensive drugs.

Sympathetic modulation by antihypertensive drugs.

AT1R Regulates Macrophage Polarization Through YAP and Regulates Aortic Dissection Incidence.

Aortic dissection (AD) is one of the most fatal cardiovascular emergency. At the anatomical level, AD occurs due to the formation of intimal tears. However, the molecular mechanism underlying this phenomenon remains unknown. Angiotensin II (Ang II) is a important effector in the development of cardiovascular disease that acts through binding to angiotensin type 1 receptor (AT1R). Yes-associated protein (YAP) was recently recognized as a key protein in macrophage activation. To determine whether AT1R and YAP are involved in macrophage-induced endothelial cell (EC) inflammation and AD incidence, we co-cultured THP-1 cells and HAECs in transwell chambers under different culture conditions and apply different conditions to the AD mice model. The results showed that Ang II promoted macrophage M1 polarization and adhesion, upregulated YAP phosphorylation, and induced EC injury that was related to increased levels of multiple pro-inflammatory chemokines. Blocking AT1R function pharmacologically or by transfection with AT1R siRNA can reduce the pro-inflammatory effect induced by Ang II. In addition, siRNA knock down of YAP expression further aggravated the pro-inflammatory effects of Ang II. Treatment with ARB effectively alleviated these pro-inflammatory effects. In the mice AD model, ARB effectively reduced the incidence of AD in mice, decreased M1 macrophages infiltration and AT1R content in the aortic wall and increased the tissue content of YAP. We found that AT1R induces YAP phosphorylation through binding to Ang II, and further promotes macrophage M1 polarization and adhesion to ECs. ARB reduces the incidence of AD in mice and affect macrophage polarization in mice aorta.

Clinical Implications

Clinical Implications

Renin Angiotensin System Inhibition as treatment for Covid-19?

Renin Angiotensin System Inhibition as treatment for Covid-19?

The anti-dipsogenic and anti-natriorexigenic effects of estradiol, but not the anti-pressor effect, are lost in aged female rats.

Estradiol (E2) inhibits fluid intake in several species, which may help to defend fluid homeostasis by preventing excessive extracellular fluid volume. Although this phenomenon is well established using the rat model, it has only been studied directly in young adults. Because aging influences the neuronal sensitivity to E2 and the fluid intake effects of E2 are mediated in the brain, we tested the hypothesis that aging influences the fluid intake effects of E2 in female rats. To do so, we examined water and NaCl intake in addition to the pressor effect after central angiotensin II treatment in young (3–4 months), middle‐aged (10–12 months), and old (16–18 months) ovariectomized rats treated with estradiol benzoate (EB). As expected, EB treatment reduced water and NaCl intake in young rats. EB treatment, however, did not reduce water intake in old rats, nor did it reduce NaCl intake in middle‐aged or old rats. The ability of EB to reduce blood pressure was, in contrast, observed in all three age groups. Next, we also measured the gene expression of estrogen receptors (ERs) and the angiotensin type 1 receptor (AT1R) in the areas of the brain that control fluid balance. ERβ, G protein estrogen receptor (GPER), and AT1R were reduced in the paraventricular nucleus of the hypothalamus in middle‐aged and old rats, compared to young rats. These results suggest the estrogenic control of fluid intake is modified by age. Older animals lost the fluid intake effects of E2, which correlated with decreased ER and AT1R expression in the hypothalamus.

Intravenous calcitriol administration regulates the renin-angiotensin system and attenuates acute lung injury in obese mice complicated with polymicrobial sepsis

Calcitriol, an active form of vitamin D, has immunomodulatory and anti-inflammatory properties. Vitamin D levels have inverse correlation with sepsis outcomes and obesity may aggravate the severity of the diseases. This study administered calcitriol to investigate its impact on sepsis-induced acute lung injury (ALI) in obese mice. Mice were fed a high-fat diet to induce obesity and were randomly assigned to control or sepsis groups, which were intravenously administered either saline (SS) or calcitriol (SD). Sepsis was induced by cecal ligation and puncture (CLP). Saline or calcitriol was injected 1 h after CLP via tail vein. Mice were sacrificed at either 12 or 24 h post-CLP and survival rates were observed. The results demonstrated that sepsis caused upregulation of inflammatory mediators and downregulation of renin-angiotensin system (RAS)-associated gene expressions in the lungs of obese mice. Cluster of differentiation 68 (CD68) expression and myeloperoxidase (MPO) activities also increased. Calcitriol treatment lowered expressions of blood and lung inflammatory mediators at 12 and/or 24 h after CLP. The RAS-proinflammatory-associated angiotensin type 1 receptor (AT1R) was lower while anti-inflammatory Mas receptor and AT2R expressions were higher at 12 h after CLP than those in the SS group. In addition, the SD group exhibited lower CD68 expression and MPO activity. Lower lung injury scores and higher survival rates were also noted in the SD group. The findings suggest that calcitriol treatment after sepsis induction upregulated RAS-associated anti-inflammatory pathway and decreased immune cell infiltration, which may have alleviated the severity of ALI of obese mice.

The ability of modern therapy to improve the prognosis of patients with HF: role of angiotensin neprilysin inhibitors and sodium-glucose cotransporter inhibitors.

Major principles for treatment of chronic heart failure with reduced left ventricular ejection fraction <40% (HFrEF) include a "triple neurohormonal blockade" as a main approach. However, in recent 6 years, two new classes of drugs for the treatment of HFrEF have appeared, which beneficially influence the prognosis. These drugs are angiotensin receptor neprilysin inhibitors (ARNI) and type 2 sodium-glucose cotransporter 2 (SGLT2) inhibitors.Aim To compare the net effect of simultaneous treatment with ARNI and SGLT2 inhibitors with the triple neurohormonal blockade in stable or decompensated patients with CHF based on Russian data.Material and methods We analyzed the risk of death per 100 patient-years in patients with HFrEF. Stable patients were followed up at the A.L. Myasnikov Institute of Cardiology (presently, A.L. Myasnikov Research Institute of Clinical Cardiology of the National Medical Research Center of Cardiology) from 2006 through 2007; data from the EPOCH-Decompensation-CHF study were used for decompensated patients (12.2 % and 36.8 %, respectively).Results When patients with stable HFrEF were successively switched from renin-angiotensin-aldosterone system (RAAS) inhibitors to ARNI (-16 %) and subsequently supplemented with SGLT2 (-13 %) the risk of death per 100 patient-years decreased from 12.2 % to 8.9 % (total risk decreased by 27 %; to save one patient the ARNI+ SGLT2 combination has to be prescribed to 30 patients). The estimated risk of death upon discharge from the hospital for the patients with decompensated CHF switched from RAAS inhibitors to ARNI (-16 %) and subsequently supplemented with SGLT2 (-13 %) was 26.9 deaths per 100 patient-years, whereas the number of patients to be treated for saving one life was only 10. Based on available data that demonstrate a greater effect of ARNI+ SGLT2 in patients immediately after CHF aggravation, the risk of death was recalculated. According to this analysis, the death rate per 1000 patient-years decreased from 36.8 to 19.9 % (relative risk decrease, 46 %), and to save one life only 6 patients had to be treated after they have achieved compensation of HFrEF.Conclusions This analysis shows the importance of early initiation of the ARNI+ SGLT2 therapy in patients with both decompensated and with stable HFrEF.

Covid-19 and Angiotensin Converting Enzyme 2(ACE2)

Renin-angiotensin system (RAS) is a signaling pathway for regulation of blood pressure, blood volume, natriuresis, and other vascular functions. In coronavirus infection disease (Covid-19), SARS-CoV-2 binds ACE2 which is highly expressed by the epithelial cells of blood vessel, intestine and lung. The expression of ACE2 is augmented by angiotensin converting enzyme inhibitors (ACEIs), angiotensin receptor blockers (ARBs), ibuprofen, statins, thiazolidinedione and by cigarette smoking. Pulmonary ACE2 is seems to be a protective defense pathway during acute respiratory distress syndrome (ARDS). Polymorphism of ACE2 has been associated with different cardio-metabolic disorders, thus implication of ACE2 and angiotensin receptor type 2 (ATR2) receptors in Covid-19-induced pneumonia should be considerably regarded with ACE2 polymorphisms. Covid-19 leads to significant lung injury through down-regulation of ACE2, which is attenuated by administration of angiotensin-receptor blockers (ARBs). Therefore, ACE2 receptors are protective against SARS-CoV-2 pathogenesis. Therefore, ACE2 is regarded as an important entry-point for SARS-CoV-2 and up-regulation of ACE2 by ACEIs, ARBs and during development of cytokine storm is regarded as a protective compensatory mechanism to overcome hyperinflammatory-induced ALI and ARDS.

Human placenta mesenchymal stem cell protection in ischemic stroke is angiotensin converting enzyme-2 and masR receptor-dependent.

Thromboembolic stroke remains a major cause of neurological disability and death. Current stroke treatments (aspirin, tissue plasminogen activator) are significantly limited by timing and risks for hemorrhage which have driven researchers to explore other approaches. Stem cell-based therapy appears to be an effective option for ischemic stroke. Besides trans-differentiation into neural cells, stem cells also provide acute protection via paracrine signaling pathways through which releasing neuroprotective factors. We previously reported that intraperitoneal administration of human placenta mesenchymal stem cell (hPMSC) therapy upon reperfusion significantly protected the brain against middle cerebral artery occlusion (MCAO)-induced injury. In the present study, we specifically investigated the role of hPMSC-derived angiotensin converting enzyme-2 (ACE-2) in protection of MCAO-induced brain injury by measurement of brain tissue viability, cerebral blood flow, and neurological score. Here, we report for the first time that hPMSC expressing substantial amount of ACE-2, which mediates hPMSC protection in the MCAO model. Strikingly, we found that the protective effects of hPMSC in MCAO-induced brain injury could be attenuated by pretreatment of hPMSCs with MLN-4760, a specific inhibitor of ACE-2 activity, or by transfection of hPMSCs with ACE-2-shRNA-lentivirus. The hPMSC-derived ACE-2 specific protective mechanism was further demonstrated by administration of PD123319, an Angiotensin type-2 receptor antagonist, or A779, a MasR antagonist. Importantly, our study demonstrated that the protective effects of hPMSC in experimental stroke are ACE-2/MasR dependent and this signaling pathway represents an innovative and highly promising approach for targeted stroke therapy.

Autoantibodies against ACE2 and angiotensin type-1 receptors increase severity of COVID-19

The renin-angiotensin system (RAS) plays a major role in COVID-19. Severity of several inflammation-related diseases has been associated with autoantibodies against RAS, particularly agonistic autoantibodies for angiotensin type-1 receptors (AA-AT1) and autoantibodies against ACE2 (AA-ACE2). Disease severity of COVID-19 patients was defined as mild, moderate or severe following the WHO Clinical Progression Scale and determined at medical discharge. Serum AA-AT1 and AA-ACE2 were measured in COVID-19 patients (n = 119) and non-infected controls (n = 23) using specific solid-phase, sandwich enzyme-linked immunosorbent assays. Serum LIGHT (TNFSF14; tumor necrosis factor ligand superfamily member 14) levels were measured with the corresponding assay kit. At diagnosis, AA-AT1 and AA-ACE2 levels were significantly higher in the COVID-19 group relative to controls, and we observed significant association between disease outcome and serum AA-AT1 and AA-ACE2 levels. Mild disease patients had significantly lower levels of AA-AT1 (p < 0.01) and AA-ACE2 (p < 0.001) than moderate and severe patients. No significant differences were detected between males and females. The increase in autoantibodies was not related to comorbidities potentially affecting COVID-19 severity. There was significant positive correlation between serum levels of AA-AT1 and LIGHT (TNFSF14; rPearson = 0.70, p < 0.001). Both AA-AT1 (by agonistic stimulation of AT1 receptors) and AA-ACE2 (by reducing conversion of Angiotensin II into Angiotensin 1-7) may lead to increase in AT1 receptor activity, enhance proinflammatory responses and severity of COVID-19 outcome. Patients with high levels of autoantibodies require more cautious control after diagnosis. Additionally, the results encourage further studies on the possible protective treatment with AT1 receptor blockers in COVID-19.

Contrasting Roles of Ang II and ACEA in the Regulation of IL10 and IL1β Gene Expression in Primary SHR Astroglial Cultures.

Angiotensin (Ang) II is well-known to have potent pro-oxidant and pro-inflammatory effects in the brain. Extensive crosstalk between the primary Ang II receptor, Ang type 1 receptor (AT1R), and the cannabinoid type 1 receptor (CB1R) has been demonstrated by various groups in the last decade. Since activation of glial CB1R has been demonstrated to play a key role in the resolution of inflammatory states, we investigated the role of Ang II (100 nM) and/or ACEA (10 nM), a potent CB1R-specific agonist in the regulation of inflammatory markers in astrocytes from spontaneously hypertensive rats (SHR) and Wistar rats. Astrocytes were cultured from brainstems and cerebellums of SHR and Wistar rats and assayed for IL1β and IL10 gene expression and secreted fraction, in treated and non-treated cells, by employing qPCR and ELISA, respectively. mRNA expression of both IL10 and IL1β were significantly elevated in untreated brainstem and cerebellar astrocytes isolated from SHR when compared to Wistar astrocytes. No changes were observed in the secreted fraction. While ACEA-treatment resulted in a significant increase in IL10 gene expression in Wistar brainstem astrocytes (Log2FC ≥ 1, p < 0.05), its effect in SHR brainstem astrocytes was diminished. Ang II treatment resulted in a strong inhibitory effect on IL10 gene expression in astrocytes from both brain regions of SHR and Wistar rats (Log2FC ≤ −1, p < 0.05), and an increase in IL1β gene expression in brainstem astrocytes from both strains (Log2FC ≥ 1, p < 0.05). Co-treatment of Ang II and ACEA resulted in neutralization of Ang II-mediated effect in Wistar brainstem and cerebellar astrocytes, but not SHR astrocytes. Neither Ang II nor ACEA resulted in any significant changes in IL10 or IL1β secreted proteins. These data suggest that Ang II and ACEA have opposing roles in the regulation of inflammatory gene signature in astrocytes isolated from SHR and Wistar rats. This however does not translate into changes in their secreted fractions.

In Aged Females, the Enhanced Pressor Response to Angiotensin II Is Attenuated By Estrogen Replacement via an Angiotensin Type 2 Receptor-Mediated Mechanism.

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Eprosartan: A closer insight into its neuroprotective activity in rats with focal cerebral ischemia-reperfusion injury.

Eprosartan (EPRO), an angiotensin receptor type-1 (AT-1) blocker, exhibited neuroprotective activities in ischemic stroke resulting from focal cerebral ischemia in rats. The current study aimed to clarify the neuroprotective role of EPRO in middle carotid artery occlusion (MCAO)-induced ischemic stroke in rats. Fifty-six male Wistar rats were divided into four groups (n = 14 per group): sham-operated group, sham receiving EPRO (60 mg/kg/day, po) group, ischemia-reperfusion (IR) group, and IR receiving EPRO (60 mg/kg/day, po) group. MCAO led to a remarkable impairment in motor function together with stimulation of inflammatory and apoptotic pathways in the hippocampus of rats. After MCAO, the AT1 receptor in the brain was stimulated, resulting in activation of Janus kinase 2/signal transducers and activators of transcription 3 signaling generating more neuroinflammatory milieu and destructive actions on the hippocampus. Augmentation of caspase-3 level by MCAO enhanced neuronal apoptosis synchronized with neurodegenerative effects of oxidative stress biomarkers. Pretreatment with EPRO opposed motor impairment and decreased oxidative and apoptotic mediators in the hippocampus of rats. The anti-inflammatory activity of EPRO was revealed by downregulation of nuclear factor-kappa B and tumor necrosis factor-β levels and (C-X-C motif) ligand 1 messenger RNA (mRNA) expression. Moreover, the study confirmed the role of EPRO against a unique pathway of hypoxia-inducible factor-1α and its subsequent inflammatory mediators. Furthermore, upregulation of caveolin-1 mRNA level was also observed along with decreased oxidative stress marker levels and brain edema. Therefore, EPRO showed neuroprotective effects in MCAO-induced cerebral ischemia in rats via attenuation of oxidative, apoptotic, and inflammatory pathways.

Chronically Hypertensive Transgenic Mice Expressing Human AT1R Haplotype‐I Exhibit Increased Susceptibility To Francisella Tularensis

Angiotensin receptor type 1 (AT1R), a G-protein coupled receptor mediates the effect of angiotensin-II and contributes to the pathophysiological consequences of metabolic disorders leading to vascular remodeling, hypertension, and end-organ damage. Genetic variations that increase human AT1R (hAT1R) expression can cause above pathological outcomes due to renin-angiotensin system overactivity. Previously we have shown that transgenic (TG) mice containing haplotype-I (Hap-I, hypertensive genotype) of human AT1R gene are more prone to develop the metabolic syndrome (MetS) related disorders as compared to the TG mice containing haplotype-II (Hap-II, normotensive genotype). We have also shown that as compared to Hap-II, the aged Hap-I TG mice overexpress the hAT1R gene resulting in an increase in blood pressure, inflammatory molecules, and renal dysfunction. Aging together with an increased risk of hypertension, can affect multiple organ systems in a complex manner, including susceptibility to various infections. The current study, therefore, was designed to examine the potential effect of aging and associated MetS disorders in our hAT1R containing TG mice model, in response to the infection by Francisella tularensis live vaccine strain (LVS) inhalation. Our results show that Hap-I TG mice have a significantly high mortality rate two weeks post-infection as compared to the Hap-II animals. Histochemical analysis of lung tissues from adult and aged animals show a comparatively elevated pathology in mice containing Hap-I of hAT1R. The lung tissue and plasma from Hap-I TG mice also show a relatively higher bacterial load five days post-infection. Preliminary RT-PCR experiments show increased inflammatory markers like IL-6, TGF-β, TNF-α, CRP and redox markers like NOX1, NOX4 in lung tissues of Hap-I TG mice. These studies suggest that haplotype dependent over-expression of hAT1R gene, leads to an enhanced mortality and lung pathology to F. tularensis LVS infection, which gets aggravated in aged animals. Clinically, our results may help in exploring the role of AT1R induced hypertension in pulmonary infections.

Metabolic Environment Alters the Transcriptomic Landscape of the Aged Heart

Eating disorders at older age are coupled with a number of unfavorable health outcomes, including cardiovascular disease; but mechanisms underlying the process remain to be clarified. For this purpose, we studied alterations in gene expression profile of hearts from aged mice following exposure to Western diet. Specifically, we used transgenic mice expressing the haplotype-I (Hap-I: hypertensive genotype) of the human angiotensin receptor type 1 (AT1R) gene because these animals are more prone to develop metabolic syndrome-related disorders. For comparison, mice containing haplotype-II of human AT1R (Hap-II: normotensive genotype) were used. Aged mice (20-24 months of age) were maintained on a regular diet or high fat diet with 2% NaCl (Western diet) for 16 weeks. Blood pressure was monitored by telemetry, whereas cardiac anatomy and gene expression profile were established on heart specimens, using histological and RNA-seq analysis. On regular diet, old Hap-I mice presented higher (~9 mmHg) systolic blood pressure, with respect to aged-matched Hap-II animals. Following administration of Wester diet, blood pressure increased in both groups of mice, but to a larger extent in Hap-I animals (~15 mmHg), in comparison to Hap-II (~7 mmHg). With respect to Hap-II, aged Hap-I mice on regular diet tended to have larger heart weight-to-body weight ratio, increased cell size, and higher levels of fibrosis. Western Diet treatment exacerbated these differences. RNA sequencing data from cardiac tissue of Hap-I aged mice revealed that Western diet significantly altered the expression of >500 genes (p-adj. <0.05). Bioinformatics analysis, using Qiagen IPA software, identified major alterations in main canonical pathways involved in cardiac function, inflammation, and oxidative damage. Top hits in the disease and biological function category included arrhythmia, chamber enlargement, and cell death. Importantly, IRF3, IRF7, IFNG and STAT1 were among the top upstream regulators significantly affected by Western diet. Overall, these results indicate that Western diet promotes hypertension, hypertrophy, and fibrosis in the heart of aged mice. These alterations are paralleled by perturbation of cardiac transcriptional profile, including upstream gene regulators.

Randomized Placebo-Controlled Trial of the Angiotensin Receptor Antagonist Losartan for Posttraumatic Stress Disorder

A large body of preclinical research and observational studies suggests that angiotensin type 1 receptor (AT1R) inhibition facilitates fear inhibition and extinction, a mechanism thought to be important for recovery from PTSD. This proposal is designed to test the efficacy of the AT1R antagonist losartan, repurposed for the treatment of PTSD.