Animal Models Of Hypertension Research Articles

Targeting IL-11 to reduce fibrocyte circulation and lung accumulation in animal models of pulmonary hypertension-associated lung fibrosis.

IL-11 is a member of the IL-6 family of cytokine initially considered as haematopoietic and cytoprotective factor. Recent evidence indicates that IL-11 promotes lung fibrosis and pulmonary hypertension in animal models and is elevated in lung tissue of patients with pulmonary fibrosis and pulmonary hypertension. Fibrocytes are bone marrow-derived circulating cells that participate in lung fibrosis and pulmonary hypertension, but the role of IL-11 on fibrocytes is unknown. We investigated the role of IL-11 system on fibrocyte activation in different in vitro and in vivo models of lung fibrosis associated with pulmonary hypertension. Human fibrocytes were isolated from peripheral blood of six healthy donors. Recombinant human (rh)-IL-11 and soluble rh-IL-11 receptor, α subunit (IL-11Rα) were used to stimulated fibrocytes in vitro to measure:- cell migration in a chemotactic migration chamber, fibrocyte to endothelial cell adhesion in a microscope-flow chamber and fibrocyte to myofibroblast transition. Mouse lung fibrosis and pulmonary hypertension was induced using either IL-11 (s.c.) or bleomycin (intra-tracheal), while in the rat monocrotaline (intra-tracheal) was used. In vivo siRNA-IL-11 was administered to suppress IL-11 in vivo. RhIL-11 and soluble rhIL-11Rα promote fibrocyte migration, endothelial cell adhesion and myofibroblast transition. Subcutaneous (s.c.) IL-11 infusion elevates blood, bronchoalveolar and lung tissue fibrocytes. SiRNA-IL-11 transfection in bleomycin and monocrotaline animal models reduces blood and lung tissue fibrocytes and reduces serum CXCL12 and CXCL12/CXCR4 lung expression. Targeting IL-11 reduces fibrocyte circulation and lung accumulation in animal models of pulmonary hypertension-associated lung fibrosis.

Breaking the Barrier: The Role of Gut Epithelial Permeability in the Pathogenesis of Hypertension.

To review what intestinal permeability is and how it is measured, and to summarise the current evidence linking altered intestinal permeability with the development of hypertension. Increased gastrointestinal permeability, directly measured in vivo, has been demonstrated in experimental and genetic animal models of hypertension. This is consistent with the passage of microbial substances to the systemic circulation and the activation of inflammatory pathways. Evidence for increased gut permeability in human hypertension has been reliant of a handful of blood biomarkers, with no studies directly measuring gut permeability in hypertensive cohorts. There is emerging literature that some of these putative biomarkers may not accurately reflect permeability of the gastrointestinal tract. Data from animal models of hypertension support they have increased gut permeability; however, there is a dearth of conclusive evidence in humans. Future studies are needed that directly measure intestinal permeability in people with hypertension.

Disrupted BMP-9 Signaling Impairs Pulmonary Vascular Integrity in Hepatopulmonary Syndrome.

Hepatopulmonary syndrome (HPS) is a severe complication of liver diseases characterized by abnormal dilatation of pulmonary vessels, resulting in impaired oxygenation. Recent research highlights the pivotal role of liver-produced bone morphogenetic protein (BMP)-9 in maintaining pulmonary vascular integrity. This study aimed to investigate the involvement of BMP-9 in human and experimental HPS. Circulating BMP-9 levels were measured in 63 healthy controls and 203 cirrhotic patients, with or without HPS. Two animal models of portal hypertension were employed: common bile duct ligation (CBDL) with cirrhosis and long-term partial portal vein ligation (PPVL) without cirrhosis. Additionally, the therapeutic effect of low-dose BMP activator FK506 was investigated, and the pulmonary vascular phenotype of BMP-9 knockout rats was analyzed. Patients with HPS related to compensated cirrhosis demonstrated lower levels of circulating BMP-9 compared to patients without HPS. Severe cirrhosis patients exhibited consistently low levels of BMP-9. In animal models, HPS characteristics, including intrapulmonary vascular dilations (IPVDs) and alveolo-arterial gradient enlargement, were observed. HPS development in both rat models correlated with reduced intrahepatic BMP-9 expression, decreased circulating BMP-9 level and activity, and impaired pulmonary BMP-9 endothelial pathway. Daily treatment with FK506 for 2-weeks restored BMP pathway in the lungs, alleviating IPVDs, and improving gas exchange impairment. Furthermore, BMP-9 knockout rats displayed a pulmonary HPS phenotype, supporting its role in disease progression. The study findings suggest that portal hypertension-induced loss of BMP-9 signaling contributes to HPS development.

An Autotaxin-Induced Ocular Hypertension Mouse Model Reflecting Physiological Aqueous Biomarker.

Animal models of ocular hypertension (OH) have been developed to understand the pathogenesis of glaucoma and facilitate drug discovery. However, many of these models are fraught with issues, including severe intraocular inflammation and technical challenges. Lysophosphatidic acid (LPA) is implicated in trabecular meshwork fibrosis and increased resistance of aqueous outflow, factors that contribute to high intraocular pressure (IOP) in human open-angle glaucoma. We aimed to elevate IOP by increasing expression of the LPA-producing enzyme autotaxin (ATX) in mouse eyes. Tamoxifen-inducible ATX transgenic mice were developed. Tamoxifen was administered to six- to eight-week-old mice via eye drops to achieve ATX overexpression in the eye. IOP and retinal thickness were measured over time, and retinal flat-mount were evaluated to count retinal ganglion cells (RGCs) loss after three months. Persistent elevation of ATX expression in mouse eyes was confirmed through immunohistochemistry and LysoPLD activity measurement. ATX Tg mice exhibited significantly increased IOP for nearly two months following tamoxifen treatment, with no anterior segment changes or inflammation. Immunohistochemical analysis revealed enhanced expression of extracellular matrix near the angle after two weeks and three months of ATX induction. This correlated with reduced outflow facility, indicating that sustained ATX overexpression induces angle fibrosis, elevating IOP. Although inner retinal layer thickness remained stable, peripheral retina showed a notable reduction in RGC cell count. These findings confirm the successful creation of an open-angle OH mouse model, in which ATX expression in the eye prompts fibrosis near the angle and maintains elevated IOP over extended periods.

Effect of hydrogen inhalation on cardiovascular and interstitial components of pulmonary hypertension in rats

Hydrogen is known to have selective antioxidant properties. It binds highly reactive hydroxyl radicals. The pathogenesis of the monocrotaline animal model of pulmonary hypertension is associated with oxidative stress and leads to all the symptoms of pulmonary hypertension (PH) and interstitial lung disease (ILD) associated with hypertension.The aim of this work was to study the effect of 4% hydrogen inhalations on the symptoms of PH and ILD in rats.Methods. To model monocrotaline-induced pulmonary hypertension (MCT-PH), two groups of animals received a single subcutaneous injection of monocrotaline (MCT) on day 1. The control group was injected subcutaneously with MCT solvent only. The animals receiving MCT were further divided into 2 subgroups. Subgroup 1 rats breathed room air and subgroup 2 rats breathed a mixture of room air and 4% hydrogen. The regular inhalations continued until day 21. On day 21, hemodynamic parameters were measured under urethane anesthesia, the heart and its components and the lungs were weighed, and lung tissue was preserved for morphological study.Results. The inhalation had no effect on the main cardiovascular symptoms of PH, but a positive effect on the state of the connective tissue of the lungs affected by PH was shown. The mast cell response was reduced both quantitatively and functionally. There was a decrease in tryptase expression by mast cells, with predominance of the forms without signs of degranulation. TGF-β secretion was also significantly reduced and visualized by immunopositive cells in alveolar cellular structures and vessel walls.Conclusion. Inhalation of 4% hydrogen reduces inflammation and fibrosis of lung tissue during the development of MCT-PH.

Insights into the associative role of hypertension and angiotensin II receptor in lower urinary tract dysfunction.

In men, the lower urinary tract comprises the urinary bladder, urethra, and prostate, and its primary functions include urine storage and voiding. Hypertension is a condition that causes multi-organ damage and an age-dependent condition. Hypertension and the renin-angiotensin system activation are associated with the development of lower urinary tract dysfunction. Hypertensive animal models show bladder dysfunction, urethral dysfunction, and prostatic hyperplasia. In the renin-angiotensin system, angiotensin II and the angiotensin II type 1 receptor, which are expressed in the lower urinary tract, have been implicated in the pathogenesis of lower urinary tract dysfunction. Moreover, among the several antihypertensives, renin-angiotensin system inhibitors have proven effective in human and animal models of lower urinary tract dysfunction. This review aimed to elucidate the hitherto known mechanisms underlying the development of lower urinary tract dysfunction in relation to hypertension and the angiotensin II/angiotensin II type 1 receptor axis and the effect of renin-angiotensin system inhibitors on lower urinary tract dysfunction. Possible mechanisms through which hypertension or activation of Ang II/AT1 receptor axis causes LUTD such as bladder dysfunction, urethral dysfunction, and prostatic hyperplasia. LUT: lower urinary tract, LUTD: lower urinary tract dysfunction, AT1: angiotensin II type 1, ACE: angiotensin-converting enzyme.

CARDIOVASCULAR EFFECTS OF FREE OR COMPLEXED LINALOOL WITH Β-CYCLODEXTRIN: A FOCUS FOR ANTIHYPERTENSIVE ACTION

Investigating the cardiovascular effects of natural compounds, such as linalool, has aroused interest due to the potential impact on cardiovascular health. Linalool, a component present in several essential oils, has demonstrated promising pharmacological properties, including antihypertensive activity. However, its bioavailability and efficacy can be influenced by complexation with β-cyclodextrin, a strategy frequently used to improve the solubility and stability of bioactive substances. This study aimed to carry out a systematic review of the literature, exploring the cardiovascular effects of free linalool and linalool complexed with β-cyclodextrin. Objective: To investigate the cardiovascular effects of free linalool and linalool complexed with β-cyclodextrin, with emphasis on the antihypertensive action, through a systematic review of the literature. Methodology: The review was conducted according to PRISMA guidelines. The PubMed, Scielo and Web of Science databases were consulted, using the descriptors "linalool", "β-cyclodextrin", "cardiovascular effects", "antihypertensive" and "complexation". The inclusion criteria covered studies published in the last 10 years, focusing on in vivo experiments, clinical trials and systematic reviews. Articles unrelated to the topic, duplicate studies and those without peer review were excluded. Results: They revealed that linalool, when complexed with β-cyclodextrin, presented greater bioavailability and stability, enhancing its antihypertensive action. In vivo studies have demonstrated a significant reduction in blood pressure in hypertensive animal models. Furthermore, the complexation positively influenced the gastrointestinal absorption of linalool. These findings suggest that the complexed formulation may represent an effective approach to improving the cardiovascular effects of linalool. Conclusion: The systematic review highlights the relevance of complexing linalool to β-cyclodextrin as a strategy to enhance its antihypertensive effects. Understanding these mechanisms can contribute to the development of more effective pharmaceutical formulations in the management of hypertension, promoting advances in cardiovascular therapy.

Animal models of hypertension: A concise review

Hypertension (HTN), a prevalent cardiovascular disorder, poses a significant global health burden. Understanding the intricate mechanisms underlying HTN is crucial for developing effective therapeutic strategies. Experimental animal models play a pivotal role in HTN research, providing valuable insights into the pathophysiology, etiology, and potential treatment options. This concise review examines the various animal models employed to study HTN, highlighting their strengths, limitations, and contributions to our understanding of this complex condition.

Co-expression of interleukin (IL)-17RA and IL-36γ in the hypothalamic paraventricular nucleus of the stress-induced hypertension rats

Objectives: The up-regulation of proinflammatory cytokines in the hypothalamic paraventricular nucleus (PVN) is well demonstrated to be involved in the development of neurogenic hypertension, including stress-induced hypertension (SIH). IL-17A has been found to be increased in the PVN of several hypertensive animal models and has been shown to play a key role in the development of hypertension. Although IL-36γ was found to be expressed in spinal neurons, its role in hypertension remains elusive. Here, we investigated the co-expression of IL-17 receptor A (IL-17RA) and IL-36γ in the PVN cells of SIH rats. Methods: The electric foot shock combined with buzzer noise stressors were used to make hypertensive rat model. The immunochemical staining or immunofluorescence staining was used to reveal cells as requested. The Western blot was used to detect the related protein levels. Results and Conclusion: In the PVN of the SIH rats, the number of CD3+CD4+ T cells was significantly increased by the immunochemical staining. Additionally, the protein levels of RORγt and IL-17A were significantly upregulated by Western blot, confirming the infiltration of CD4+ T cells and differentiation into Th17 cells in the PVN of SIH rats. Immunofluorescence staining revealed abundant expression of IL-17RA in PVN neurons, with relatively less expression in astrocytes or microglia. Furthermore, IL-36γ positive cells and protein expression of IL-36R were significantly increased. Notably, this study demonstrates for the first time that most IL-36γ cells were strongly colocalized with IL-17RA positive cells in the PVN of SIH rats, and the colocalized cells were significantly higher in SIH rats. This suggests that IL-17A secreted by infiltrated Th17 cells may stimulate PVN neurons to produce IL-36γ via IL-17RA, indicating that the combination of IL-17 and IL-36γ might produce strong pro-inflammatory effects in the PVN of SIH rats.

Study of the single or combined action of three different neuroprotection strategies in an acute hypertension model in mice

Aims/Purpose: To study the neuroprotective effects of a TrkB receptor activator (DHF), a calcium channel blocker that prevents Ca2+ toxic influx (ITH12657) and/or a P2X7 receptor blocker (ITH15004) administered alone or in combination in an animal model of acute ocular hypertension (AOHT).Methods: Pigmented adult mice (C57BL/6 strain) were separated into 9 experimental groups (n = 8 per group), 7 received intraperitoneal injections of the neuroprotective drugs alone or in combination, 1 received saline as the vehicle group and 1 was naïve. AOHT was performed by connecting the anterior chamber of the left eye to a bottle of saline at a height of 130 cm achieving an intraocular pressure of 97 mmHg for 60 min. Longitudinally in vivo analysis of the pSTR amplitude and the inner retinal thickness was measured by electroretinogram and SD‐OCT, respectively; and ex vivo analysis of the retinal ganglion cell population was identified immunohistochemically by Brn3a at 7 after AOHT in all experimental groups.Results: The neuroprotectant treatment administered alone had a beneficial effect on the pSTR wave response amplitude (50–60% amplitude response) compared to vehicles (⁓25% amplitude response), which increased in all treatment combinations (⁓75%) except for ITH12657+ ITH15004 at 7 days after AOHT. Similar results were obtained in the inner retinal thickness, with the combined treatments producing a better retinal response after 7 days of AOHT, particularly for DHF + ITH15004 and DHF + ITH12657 + ITH15004 which showed no difference compared to control thicknesses. Regarding the RGC population, all treatments had a neuroprotective effect (⁓70% population survival at 7 days) compared to vehicles (⁓40%) which was not increased by their combination.Conclusions: The single or combined action of three different neuroprotective strategies results in functional and morphological protection of the retina 7 days after AOHT.

Renal protective effects of natural honey on animal model of hypertension

Hypertension, also known as high blood pressure, is a leading cause of cardiovascular disease and premature death worldwide. Numerous investigations have established that hypertension can cause alterations in the cardiovascular system as well as renal structure and function. Fresh honey is consumed worldwide and is claimed to be highly medicinal and has therapeutic effects against a wide range of medical conditions. We investigated the renal protective effect of natural honey in in animal model of hypertension. Forty (40) male albino rats, with average weight (120 ±10 g) were administered with high salt diet, HSD (80 g NaCl + 1 kg of diet and 1% NaCl in drinking water (10 g of NaCl + 1 L distilled water) for 10 weeks to induce hypertension in the rats. Following confirmation, hypertensive male rats were randomly selected for the experiment. Twenty (20) albino rats (15 hypertensive rats and 5 normotensive rats) were divided into 4 groups, Groups A-D. Group A: (Normotensive Control) no administration was given; Groups B-D (hypertensive rats) received the following treatments. Group B was treated with natural honey (15 ml/kg), Group C treated with hydrochlorothiazide (0.15 mg/kg), daily for 21 days; while Group D received no treatment, until the end of the 21 days administrations. Blood samples were taken in the end, and renal alterations were assessed via biochemical and histopathological analyses. Results showed that salt-induced hypertension caused a marked elevation of the renal biochemical parameters. The histopathological results agree with the biochemical findings. However and interestingly, natural honey (15 ml/kg. oral) showed significant efficacy in the recovery and protection on the kidney as the standard anti-hypertensive drug, hydrochlorothiazide (p < 0.05 or p < 0.01). Natural honey has a renal protective effects and may manage renal hypertension or prevent kidney injury secondary to high blood pressure.

Batteryless implantable device with built-in mechanical clock for automated and precisely timed drug administration.

Adherence to medication plays a crucial role in the effective management of chronic diseases. However, patients often miss their scheduled drug administrations, resulting in suboptimal disease control. Therefore, we propose an implantable device enabled with automated and precisely timed drug administration. Our device incorporates a built-in mechanical clock movement to utilize a clockwork mechanism, i.e., a periodic turn of the hour axis, enabling automatic drug infusion at precise 12-h intervals. The actuation principle relies on the sophisticated design of the device, where the rotational movement of the hour axis is converted into potential mechanical energy and is abruptly released at the exact moment for drug administration. The clock movement can be charged either automatically by mechanical agitations or manually by winding the crown, while the device remains implanted, thereby enabling the device to be used permanently without the need for batteries. When tested using metoprolol, an antihypertensive drug, in a spontaneously hypertensive animal model, the implanted device can deliver drug automatically at precise 12-h intervals without the need for further attention, leading to similarly effective blood pressure control and ultimately, prevention of ventricular hypertrophy as compared with scheduled drug administrations. These findings suggest that our device is a promising alternative to conventional methods for complex drug administration.

CD4+ T-Cell Legumain Deficiency Attenuates Hypertensive Damage via Preservation of TRAF6.

T cells are central to the immune responses contributing to hypertension. LGMN (legumain) is highly expressed in T cells; however, its role in the pathogenesis of hypertension remains unclear. Peripheral blood samples were collected from patients with hypertension, and cluster of differentiation (CD)4+ T cells were sorted for gene expression and Western blotting analysis. TLGMNKO (T cell-specific LGMN-knockout) mice (Lgmnf/f/CD4Cre), regulatory T cell (Treg)-specific LGMN-knockout mice (Lgmnf/f/Foxp3YFP Cre), and RR-11a (LGMN inhibitor)-treated C57BL/6 mice were infused with Ang II (angiotensin II) or deoxycorticosterone acetate/salt to establish hypertensive animal models. Flow cytometry, 4-dimensional label-free proteomics, coimmunoprecipitation, Treg suppression, and in vivo Treg depletion or adoptive transfer were used to delineate the functional importance of T-cell LGMN in hypertension development. LGMN mRNA expression was increased in CD4+ T cells isolated from hypertensive patients and mice, was positively correlated with both systolic and diastolic blood pressure, and was negatively correlated with serum IL (interleukin)-10 levels. TLGMNKO mice exhibited reduced Ang II-induced or deoxycorticosterone acetate/salt-induced hypertension and target organ damage relative to wild-type (WT) mice. Genetic and pharmacological inhibition of LGMN blocked Ang II-induced or deoxycorticosterone acetate/salt-induced immunoinhibitory Treg reduction in the kidneys and blood. Anti-CD25 antibody depletion of Tregs abolished the protective effects against Ang II-induced hypertension in TLGMNKO mice, and LGMN deletion in Tregs prevented Ang II-induced hypertension in mice. Mechanistically, endogenous LGMN impaired Treg differentiation and function by directly interacting with and facilitating the degradation of TRAF6 (tumor necrosis factor receptor-associated factor 6) via chaperone-mediated autophagy, thereby inhibiting NF-κB (nuclear factor kappa B) activation. Adoptive transfer of LGMN-deficient Tregs reversed Ang II-induced hypertension, whereas depletion of TRAF6 in LGMN-deficient Tregs blocked the protective effects. LGMN deficiency in T cells prevents hypertension and its complications by promoting Treg differentiation and function. Specifically targeting LGMN in Tregs may be an innovative approach for hypertension treatment.

Histone Modifications and Their Contributions to Hypertension.

Essential hypertension, a multifaceted disorder, is a worldwide health problem. A complex network of genetic, epigenetic, physiological, and environmental components regulates blood pressure (BP), and any dysregulation of this network may result in hypertension. Growing evidence suggests a role for epigenetic factors in BP regulation. Any alterations in the expression or functions of these epigenetic regulators may dysregulate various determinants of BP, thereby promoting the development of hypertension. Histone posttranslational modifications are critical epigenetic regulators that have been implicated in hypertension. Several studies have demonstrated a clear association between the increased expression of some histone-modifying enzymes, especially HDACs (histone deacetylases), and hypertension. In addition, treatment with HDAC inhibitors lowers BP in hypertensive animal models, providing an excellent opportunity to design new drugs to treat hypertension. In this review, we discuss the potential contribution of different histone modifications to the regulation of BP.

Sinapine targeting PLCβ3 EF hands disrupts Gαq-PLCβ3 interaction and ameliorates cardiovascular diseases

BackgroundThe renin-angiotensin-aldosterone system (RAAS) over-activation is highly involved in cardiovascular diseases (CVDs), with the Gαq-PLCβ3 axis acting as a core node of RAAS. PLCβ3 is a potential target of CVDs, and the lack of inhibitors has limited its drug development. PurposeSinapine (SP) is a potential leading compound for treating CVDs. Thus, we aimed to elucidate the regulation of SP towards the Gαq-PLCβ3 axis and its molecular mechanism. Study designAldosteronism and hypertension animal models were employed to investigate SP's inhibitory effect on the abnormal activation of the RAAS through the Gαq-PLCβ3 axis. We used chemical biology methods to identify potential targets and elucidate the underlying molecular mechanisms. MethodsThe effects of SP on aldosteronism and hypertension were evaluated using an established animal model in our laboratory. Target identification and underlying molecular mechanism research were performed using activity-based protein profiling with a bio-orthogonal click chemistry reaction and other biochemical methods. ResultsSP alleviated aldosteronism and hypertension in animal models by targeting PLCβ3. The underlying mechanism for blocking the Gαq-PLCβ3 interaction involves targeting the EF hands through the Asn-260 amino acid residue. SP regulated the Gαq-PLCβ3 axis more precisely than the Gαq-GEFT or Gαq-PKCζ axis in the cardiovascular system. ConclusionSP alleviated RAAS over-activation via Gαq-PLCβ3 interaction blockade by targeting the PLCβ3 EF hands domain, which provided a novel PLC inhibitor for treating CVDs. Unlike selective Gαq inhibitors, SP reduced the risk of side effects compared to Gαq inhibitors in treating CVDs.

Herbal medicine (Oryeongsan) for fluid and sodium balance in renal cortex of spontaneously hypertensive rats

BackgroundHerbal medicine Oryeongsan (ORS), also known as Wulingsan in Chinese, has been used for the treatment of impaired body fluid balance. However, the mechanisms involved are not clearly defined. The purpose of the present study was to identify the actions of ORS on the renal excretory function and blood pressure (BP) and to define the mechanisms involved in association with renin-angiotensin system (RAS) and natriuretic peptide system (NPS) in spontaneously hypertensive rats (SHR), an animal model of human essential hypertension. MethodsChanges in urine volume (UV), excretion of electrolytes including Na+ (urinary excretion of Na+ (UNaV)) were measured. RT-PCR was performed to trace the changes in expression of RAS, NPS and sodium (Na+)-hydrogen (H+) exchanger 3 (NHE3) in the renal cortex. ResultsIn the SHR treated with vehicle (SHR-V) group, UV and UNaV were suppressed and the Na+ balance was maintained at the higher levels leading to an increase in BP compared to WKY-V group. These were accompanied by an increase in NHE3 expression with an accentuation of angiotensin I converting enzyme-angiotensin II type 1 (ACE-AT1) receptor and concurrent suppression of angiotensin II type 2 (AT2) receptor/ACE2-Mas receptor expression in the renal cortex. Chronic treatment with ORS increased UV and UNaV, and decreased the Na+ and water balance with a decrease in BP in the ORS-treated SHR-ORS group compared to SHR-V. These were accompanied by a decrease in NHE3 expression with a suppression of ACE-AT1 receptor and concurrent accentuation of AT2/ACE2-Mas receptor. ConclusionThe present study shows that ORS reduced BP with a decrease in Na+ and water retention by a suppression of NHE3 expression via modulation of RAS and NPS in SHR. The present study provides pharmacological rationale for the treatment of hypertension with ORS in SHR.

Inhibition of insulin-regulated aminopeptidase confers neuroprotection in a conscious model of ischemic stroke

Stroke is a leading cause of mortality and morbidity with a paucity of effective pharmacological treatments. We have previously identified insulin-regulated aminopeptidase (IRAP) as a potential target for the development of a new class of drugs for the treatment of stroke, as global deletion of this gene in mice significantly protected against ischemic damage. In the current study, we demonstrate that small molecular weight IRAP inhibitors reduce infarct volume and improve neurological outcome in a hypertensive animal model of ischemic stroke. The effects of two structurally distinct IRAP inhibitors (HFI419 or SJM164) were investigated in a model of stroke where the middle cerebral artery was transiently occluded with endothelin-1 in the conscious spontaneously hypertensive rat. IRAP inhibitor was administered into the lateral ventricle at 2 or 6 h after stroke, with subsequent doses delivered at 24, 48 and 70 h post-stroke. Functional outcomes were assessed prior to drug treatment, and on day 1 and 3 post-stroke. Histological analyses and neuroinflammatory cytokine profiling were conducted at 72 and 24 h post-stroke respectively. IRAP inhibitor treatment following stroke significantly reduced infarct volume and improved neurological and motor deficits. These protective effects were maintained even when the therapeutic window was extended to 6 h. Examination of the cellular architecture at 72 h post-stroke demonstrated that IRAP expression was upregulated in CD11b positive cells and activated astrocytes. Furthermore, IRAP inhibitor treatment significantly increased gene expression for interleukin 6 and C–C motif chemokine ligand 2 in the ischemic core. This study provides proof-of-principle that selective inhibition of IRAP activity with two structurally distinct IRAP inhibitors reduces infarct volume and improves functional outcome even when the first dose is administered 6 h post-stroke. This is the first direct evidence that IRAP inhibitors are a class of drug with potential use in the treatment of ischemic stroke.

Right ventricular diastolic adaptation to pressure overload in different rat strains

Abstract Background Different rat strains are used in various animal models of pulmonary hypertension and right ventricular (RV) failure. No systematic assessment has been performed to test differences in RV response to pressure overload between rat strains. Purpose We compared RV adaptation to pulmonary trunk banding (PTB) in Wistar, Sprague Dawley, and Fischer344 rats by hemodynamic profiling focusing on diastolic function. Methods Age-matched male rat weanlings were randomized to sham operation (Wistar sham, n=5; Sprague Dawley sham, n=4; Fischer344 sham, n=4) or PTB (Wistar PTB, n=8; Sprague Dawley PTB, n=8; Fischer344 PTB, n=8). RV function was evaluated after five weeks by echocardiography, cardiac MRI, and invasive pressure-volume measurements and RV remodelling assessed by histological analyses. Results At end of study, Fischer344 rats weighed 25 % less than Wistar and Sprague Dawley rats. PTB increased RV systolic pressures four-fold, and RV failure was evident by a decrease in cardiac index (Wistar PTB: 1.8±0.2 mL/s/m2 vs. Wistar sham: 3.9±0.2 mL/s/m2, p<0.0001; Sprague Dawley PTB: 1.7±0.1 mL/s/m2 vs. Sprague Dawley sham: 3.0±0.3 mL/s/m2, p=0.0029; Fischer344 PTB: 2.1±0.2 mL/s/m2 vs. Fischer344 sham: 3.8±0.3 mL/s/m2, p<0.0001). There was a 2.4-fold increase in RV end-systolic volume index in Wistar PTB and Sprague Dawley PTB compared with sham, while Fischer344 PTB rats were less affected with only a 2.0-fold increase in RV end-systolic volume index compared with Fischer344 sham. Diastolic and right atrial impairment were evident by increased end-diastolic elastance, filling pressure, and E/e’ in PTB rats compared with sham, again Fischer344 PTB the least affected. PTB increased RV fibrosis in all groups compared with sham, though Fischer344 PTB showed a trend towards a smaller increase in RV fibrosis (Fischer344 PTB: 9.2±0.4 % vs Wistar PTB: 10.7±0.2 %, p=0.0919). Conclusions PTB caused RV failure in all rats subjected to the procedure including signs of diastolic dysfunction. Despite similar increase in RV systolic pressure, Fischer344 PTB rats showed less RV dilatation and where more able to sustain diastolic function compared with Wistar and Sprague Dawley PTB rats. All three rat strains are suitable for PTB and studies of RV failure.

Chronic red laser treatment induces hypotensive effect in two-kidney one-clip model of renovascular hypertension in rat.

To evaluate whether the chronic effect of photobiomodulation therapy (PBM) onsystolic arterial pressure (SAP)from two kidneys one clip (2K-1C) hypertension animal models can cause a hypotensive effect. Serum levels of nitric oxide were also analyzed and the assessment of lipid peroxidation of the thoracic aorta artery. Male Wistar rats were used. Hypertensive animals (2K-1C) with Systolic arterial pressure (SAP) greater than or equal to 160mmHg were used. Systolic arterial pressure (SAP) was determined by the tail plethysmography technique. Normotensive (2K) and hypertensive (2K-1C) rats were treated to PBM for 4weeks using a laser whose irradiation parameters were: red wavelength (λ) = 660nm: operating continuously; 56s per point (3 points) spot size = 0.0295 cm2; average optical power of 100 mW; energy of 5.6J per point; irradiance of 3.40 W/cm2; fluency of 190J/cm2 per point. The application was on the animals tails, at 3 different points simultaneously, in contact with the skin. To assess serum nitrite and nitrate (NOx) levels, blood collection was performed after chronic PBM treatment, 24h after the last laser application. The evaluation of the lipid peroxidation of the thoracic aorta artery was performed by measuring the concentration of hydroperoxide by the FOX method. Chronic photobiomodulation therapy (PBM) by red laser (660nm) can induce a hypotensive effect in 64% of 2K-1C hypertensive animals, which we say responsive animals. There was no difference in serum NO levels 24h after the last red laser application, between treated and non-treated groups. Aortic rings from 2K-1C hypertensive animals present a higher lipid peroxidation. The chronic PBM treatment by red laser decreased aortic rings lipid peroxidation in hypertensive responsive groups, compared to control. our results indicate that chronic PBM made by red laser has an important hypotensive effect in renovascular hypertensivemodels, by a mechanism that involves decrease in oxidative stress from vascular beds.

Light at the ENDothelium-role of Sox17 and Runx1 in endothelial dysfunction and pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a progressive disease that is characterized by an obliterative vasculopathy of the distal pulmonary circulation. Despite significant progress in our understanding of the pathophysiology, currently approved medical therapies for PAH act primarily as pulmonary vasodilators and fail to address the underlying processes that lead to the development and progression of the disease. Endothelial dysregulation in response to stress, injury or physiologic stimuli followed by perivascular infiltration of immune cells plays a prominent role in the pulmonary vascular remodeling of PAH. Over the last few decades, our understanding of endothelial cell dysregulation has evolved and brought to light a number of transcription factors that play important roles in vascular homeostasis and angiogenesis. In this review, we examine two such factors, SOX17 and one of its downstream targets, RUNX1 and the emerging data that implicate their roles in the pathogenesis of PAH. We review their discovery and discuss their function in angiogenesis and lung vascular development including their roles in endothelial to hematopoietic transition (EHT) and their ability to drive progenitor stem cells toward an endothelial or myeloid fate. We also summarize the data from studies that link mutations in Sox17 with an increased risk of developing PAH and studies that implicate Sox17 and Runx1 in the pathogenesis of PAH. Finally, we review the results of recent studies from our lab demonstrating the efficacy of preventing and reversing pulmonary hypertension in animal models of PAH by deleting RUNX1 expression in endothelial or myeloid cells or by the use of RUNX1 inhibitors. By investigating PAH through the lens of SOX17 and RUNX1 we hope to shed light on the role of these transcription factors in vascular homeostasis and endothelial dysregulation, their contribution to pulmonary vascular remodeling in PAH, and their potential as novel therapeutic targets for treating this devastating disease.