Aortic Rings Research Articles

Abstract 16831: Deficiency of Cholesterol Efflux Pathways in Smooth Muscle Cells Enhances Vasoconstriction but Does Not Affect Atherosclerosis

Smooth muscle cells (SMCs) regulate blood flow distribution via vasoconstriction mediated by α-adrenergic receptors (α-ARs). Plasma membrane cholesterol may affect α 1 -AR signaling, but consequences for SMC-mediated vasoconstriction are unclear. Cholesterol loading promotes SMC to macrophage transition in vitro , which may enhance atherosclerotic plaque vulnerability. However, the role of ATP Binding Cassette A1 and G1 (ABCA1/G1)-cholesterol efflux pathways in SMC-mediated vasoconstriction and atherogenesis remains poorly understood. We generated mice with SMC-specific Abca1/g1 deficiency on the low-density lipoprotein receptor deficient ( Ldlr -/- ) background by crossbreeding Abca1 fl/fl Abcg1 fl/fl Ldlr -/- mice with Myh11-Cre ERT2 transgenic mice and feeding them tamoxifen-diet. To induce SMC cholesterol accumulation and atherogenesis, we fed Myh11-Cre ERT2 Abca1 fl/fl Abcg1 fl/fl Ldlr -/- and Myh11-Cre ERT2 Ldlr -/- mice Western-type diet (WTD) for 16 weeks. Combined SMC-Abca1/g1 deficiency increased vasoconstriction in aortic rings induced by the α 1 -AR agonist phenylephrine, with reversal by methyl-β-cyclodextrin, substantiating its cholesterol-dependency. Unexpectedly, SMC - Abca1/g1 deficiency induced urinary bladder enlargement by >20-fold, resembling bladder outlet obstruction (BOO). This was reversed by the α 1 -AR antagonist tamsulosin, indicating its dependence on SMC constriction. Moreover, SMC - Abca1/g1 deficiency decreased SMC markers and increased macrophage- and fibroblast-markers in the bladder wall, enhancing collagen deposition, consistent with SMC transdifferentiation. However, after 16 weeks WTD, SMC - Abca1/g1 deficiency did not affect atherosclerotic lesion size, fibrous cap thickness, necrotic core, collagen, or macrophage content, suggesting that SMCs in atherosclerotic plaques were not affected. This may be due to low Abca1/g1 expression in intimal SMCs. We uncover a new role of SMC cholesterol efflux pathways in suppressing α 1 -AR mediated vasoconstriction and bladder SMC transdifferentiation, decreasing BOO. Our data may provide a mechanistic link for the association between BOO and diabetes in humans, particularly because diabetes is associated with decreased cholesterol efflux.

Abstract 11795: CXCL5 Inhibition Recovers Neovascularization in Diabetes Mellitus

Introduction: Diabetes mellitus (DM) is a chronic inflammatory disease accompanied by dysfunction of vascular endothelial cells. Vascular complications are the main causes of death in patients with DM. CXCL5 is an inflammatory chemokine that upregulated in patients with type 2 DM. However, its role in diabetic vasculopathy was not clarified. This study aimed to explore the impacts and mechanistic insights of CXCL5 in neovasculogenesis in DM. Methods: Endothelial progenitor cells (EPCs) and human aortic endothelial cells (HAECs) were used in vitro. Streptozotocin-induced diabetic mice and dbdb mice were used as type 1 and type 2 DM models. CXCL5 knockout mice were also used to generate the diabetic animal model. The hindlimb ischemia surgery, matrigel plug assay, and aortic ring assay were conducted. Flow cytometry were used to evaluate the circulating number of EPCs. Results: CXCL5 concentrations were increased in plasma and EPCs culture medium from type 2 DM patients. CXCL5 inhibition by neutralizing antibody upregulated VEGF/SDF-1 expression and improved migration and tube formation abilities in EPCs from type 2 DM patients and high glucose-treated EPCs from non-diabetic subjects as well as HAECs. Intraperitoneal injection of CXCL5 neutralizing antibody increased circulating EPC number, enhanced capillary density, and recovered the blood flow after hindlimb ischemia surgery in both type 1 and type 2 diabetic animals. Protein levels of VEGF and SDF-1 in ischemic muscle were upregulated in the CXCL5 inhibition group. Additionally, diabetic mice injected with CXCL5 neutralizing antibody showed higher hemoglobin contents and neovascular branches in the matrigel plug assay and aortic ring assay, respectively. Importantly, CXCL5 knockout diabetic mice showed improved ischemia-induced angiogenesis and higher expression of angiogenic proteins in ischemic muscle compared with wild-type diabetic mice. Conclusion: CXCL5 inhibition can improve neovasculogenesis via protecting vascular endothelial function and upregulating angiogenic protein expressions in both type 1 and type 2 DM. Further clinical studies are needed to verify that CXCL5 may be a potential therapeutic target for DM vascular complications.

Alkaloids from <i>Peganum harmala</i> attenuated contractile responses of vascular smooth muscle cells

Purpose: To investigate the contractile responses of vascular smooth muscle cells (VSMCs) to spasmogens after incubation with harmaline, harmine, and harmalol, which are alkaloids obtained from Peganum harmala L., a member of the Zygophyllaceae family.
 Methods: Contractile responses of VSMCs to norepinephrine (NE; 1 µmol/L) and potassium chloride (KCl; 60 mmol/L) were recorded in rat aortic ring preparations pre-incubated with 0.5, 1, 5 and 10 µmol/L of each alkaloid for 15 min. Responses were expressed as mean values of contractions in incubated preparations, relative to the recorded tension prior to treatment with alkaloids.
 Results: Pre- incubation with harmaline at concentration of 10 µmol/L significantly reduced contractile responses to NE by 69.0 ± 3.0 % (p < 0.00002), and decreased KCl-induced contraction by 34.0 ± 9.0 % (p < 0.05). Harmalol was the most effective in inhibiting contractions to KCl (48.0 ± 9.0 %, p < 0.01). However, harmalol produced relatively moderate inhibitory effects on NE-induced contractions (46.0 ± 4.0 %, p < 0.005), followed by harmine (52.0 ± 8.0 %, p < 0.02), but it did not significantly affect contractile responses to KCl.
 Conclusion: These results highlight the differential effects of pre-incubation with alkaloids from P. harmala and their potential effects on the prevention of VSMC spasms induced by either chemicals or stimuli that change the membrane potential.

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.

Obesity-Induced Platelet Mitofusin-1 Expression Causes Vascular Dysfunction

Background: The growing epidemic of obesity is strongly linked to cardiovascular disease (CVD). Obesity leads to endothelial dysfunction, an instigating event that drives vascular injury and subsequent CVD, but the mechanisms by which obesity causes endothelial dysfunction remain unclear. Platelets circulate proximal to the endothelium and are traditionally thought to contribute to obesity-associated vasculopathy through thrombotic activation. However, platelets are metabolically active and release vaso-modulatory molecules into their environment and the role of these functions have not been examined in the context of obesity-induced vasculopathy. We previously showed that alterations in platelet mitochondrial function regulate platelet degranulation. Further, it has been reported that thrombospondin 1 (TSP1), a platelet factor that propagates endothelial dysfunction, is elevated in the plasma of obese humans. We hypothesized that obesity/weight gain modulates platelet mitochondrial function, which stimulates the release of TSP1 from platelets to propagate vascular dysfunction. Methods: Platelets were isolated from lean and obese humans and mitochondrial structure and function measured. To induce diet-induced obesity wildtype (WT) mice were fed with a high fat diet (HFD, 60 kcal% fat) for 10 weeks, and low fat diet (LFD, 10 kcal% fat)- fed WT mice were used as controls. Platelets and plasma from the mice were screened for mitochondrial proteins and plasma TSP-1 was measured by ELISA. A murine model with platelet-specific deletion of mitofusin-1 (MFN1; pltMFN1KO mice), a mitochondrial GTP-ase that increases mitochondrial function was generated and fed either HFD or LFD for 4-10 weeks. Further, endothelial-dependent- and independent- vascular relaxation was measured in both groups by stimulating aortic rings with acetylcholine (Ach) or sodium nitroprusside (SNP) using wire myography. Additionally, platelet-specific TSP1 knockout (plt-TSP1KO) mice were generated and fed with HFD for 10 weeks and measured plasma TSP1 levels. Results: Platelets from obese subjects showed increased levels of MFN1 compared to lean subjects. WT mice fed with HFD had increased platelet MFN1 and plasma TSP1 levels compared to LFD-fed WT mice. Platelet-specific deletion of MFN1 in mice resulted in reduced plasma TSP1 levels compared to control PF4-cre mice after HFD challenge. We found that HFD caused impaired Ach-stimulated vasorelaxation (indicative of endothelial dysfunction) in control PF4-cre mice, and this effect was attenuated in pltMFN1KO mice. Further, we found that HFD-induced increases in plasma TSP1 levels were attenuated in plt-TSP1KO mice, indicating platelets are the major source of TSP1 in HFD induced obesity model. Conclusion: These data demonstrate that obesity/weight gain induces platelet MFN1 expression, which drives TSP1 release from platelets to propagate vascular dysfunction. Our findings elucidate a novel platelet-centric mechanism underlying obesity-associated vasculopathy and have implications for the targeting of non-thrombotic platelet function as a therapeutic strategy for obesity-induced vasculopathy.

Ammodaucus leucotrichus Acts as an Antihypertensive and Vasorelaxant Agent Through sGC and Prostaglandin Synthesis Pathways.

Ammodaucus leucotrichus is a medicinal plant used in traditional medicine to treat various ailments, including hypertension. The study aimed to determine the antihypertensive activity of Ammodaucus leucotrichus. The study aimed to investigate the antihypertensive and vasorelaxant activities of the aqueous extract of Ammodaucus leucotrichus fruits (ALAE) in rats. ALAE was prepared to study its antihypertensive effect in L-NAME (Nω-L-arginine methyl ester)-induced hypertensive rats and its vasorelaxant activity in isolated thoracic aortas of rats. The acute and subchronic effects of ALAE on systolic, diastolic, mean arterial pressure, and heart rate (HR) were evaluated after oral administration of ALAE (60 and 100 mg/kg body weight) for 6 h for the acute experiment and over 7 days for the subchronic test. Isolated thoracic aortic rings were prepared to examine the vasorelaxant action of ALAE. Several common pharmacological agents were used to test potential pathways implicated in vasorelaxant action. The results showed that ALAE reduced blood pressure parameters (systolic, mean, and diastolic blood pressure) in L-NAME-induced hypertension rats after repeated oral treatment over seven days without affecting normotensive rats. Furthermore, in thoracic aortic rings pre-contracted with epinephrine (EP) (10 μM) or KCl (80 mM), ALAE (0.250-1.625 mg/ml) showed a vasorelaxant effect. In isolated rat thoracic aortas, blockage of soluble guanylyl cyslase with blue methylene (P < 0.01) partially decreased this vasorelaxant effect. In addition, blockage of the prostaglandin synthesis pathway with indomethacin (P<0.05) also reduced the vasorelaxant activity of ALAE. Pretreatment of aortic rings with glibenclamide, propanolol, L-NAME, MLN-4760, or nifedipine did not affect ALAE-induced vasorelaxation. Ammodaucus leucotrichus is a prescient medicinal plant, able to act as an antihypertensive agent. Moreover, the results suggest that the extract increased cGMP in NO-independent manner.

ATP promotes resident CD34+ cell migration mainly through P2Y2-Stim1-ERK/p38 pathway.

Extracellular adenosine triphosphate (ATP) is one of the most abundant biochemical constitutes within the stem cell microenvironment and is postulated to play critical roles in cell migration. However, it is unclear whether ATP regulates the cell migration of CD34+ vascular wall-resident stem/progenitor cells (VW-SCs) and participates in angiogenesis. Therefore, the biological mechanisms of cell migration mediated by ATP was determined by in vivo subcutaneous matrigel plug assay, ex vivo aortic ring assay, in vitro transwell migration assay, and other molecular methods. In the present study, ATP dose-dependently promoted CD34+ VW-SCs migration, which was more obviously attenuated by inhibiting or knocking down P2Y2 than P2Y6. Furthermore, it was confirmed that ATP potently promoted the migration of resident CD34+ cells from cultured aortic artery rings and differentiation into endothelial cells in matrigel plugs by using inducible lineage tracing Cd34-CreERT2; R26-tdTomato mice, whereas P2Y2 and P2Y6 blocker greatly inhibited the effect of ATP. In addition, ATP enhanced the protein expression of stromal interaction molecule 1 (STIM1) on cell membrane, blocking the calcium release-activated calcium (CRAC) channel with shSTIM1 or BTP2 apparently inhibited ATP-evoked intracellular Ca2+ elevation and channel opening, thereby suppressing ATP-driven cell migration. Moreover, extracellular signal-regulated protein kinase (ERK) inhibitor PD98059 and p38 inhibitor SB203580 remarkably inhibited ERK and p38 phosphorylation, cytoskeleton rearrangement, and subsequent cell migration. Unexpectedly, it was found that knocking down STIM1 greatly inhibited ATP-triggered ERK/p38 activation. Taken together, it was suggested that P2Y2 signaled through the CRAC channel mediated Ca2+ influx and ERK/p38 pathway to reorganize the cytoskeleton and promoted the migration of CD34+ VW-SCs.NEW & NOTEWORTHY In this study, we observed that the purinergic receptor P2Y2 is critical in the regulation of vascular wall-resident CD34+ cells' migration. ATP could activate STIM1-mediated extracellular Ca2+ entry by triggering STIM1 translocation to the plasma membrane, and knockdown of STIM1 prevented ERK/p38 activation-mediated cytoskeleton rearrangement and cell migration.

Antihypertensive Effect of Euphorbia cheiradenia in Rats.

The study aimed to investigate the effect of Euphorbia cheiradenia on blood pressure. Euphorbia cheiradenia is a medicinal plant with several medicinal properties. This study aimed to study the vasorelaxant and antihypertensive capacity of the aqueous extract of Euphorbia cheiradenia (E. cheiradenia), and to evaluate its effect on angiotensinconverting enzyme 2 (ACE2). The antihypertensive ability of aerial parts of the aqueous extract of E. cheiradenia (AEEC) was investigated in L-NAME-induced hypertensive rats, and its vasorelaxant effect was performed on the isolated thoracic rat aorta. In addition, the possible inhibitory effect of AEEC on ACE2 was also studied. AEEC lowered blood pressure parameters in hypertensive rats. The study of the vasorelaxant activity revealed that AEEC partially relaxed the aortic rings through activation of the KATP channel and inhibition of the β-adrenergic pathway. Whereas pretreatment of aortic rings with nifedipine, indomethacin, L-NAME, and methylene blue did not attenuate AEEC-induced vasorelaxation. However, AEEC did not affect ACE2 in isolated rat aortas. The study showed that aqueous E. cheiradenia extract exhibits significant antihypertensive activity in hypertensive rats.

Endothelium-dependent vasorelaxation effects of F5 fraction of Crinum amabile chloroform extract

BackgroundVascular dysfunction can lead to many health problems including hypertension and heart disease. The complexities of vascular dysfunction and vascular disorder-related diseases have prompted the search for many new biologically active compounds in the efforts of resolving the problems. Previous studies have shown that Amaryllidaceae alkaloids exert multiple biological activities, including the vasorelaxation effect. Crinum amabile, which is a family member of Amaryllidaceae, is believed to possess a promising pharmacological activity as a vasorelaxant.MethodThe vasorelaxation activities of Crinum amabile extracts and fractions were determined using in vitro models of phenylephrine pre-contracted intact and denuded rat aortic rings. The mechanistic pathways of vasorelaxation were investigated by pre-treatment of endothelium-intact rat aortic rings with L-NG Nitro Arginine Methyl Ester (L-NAME), methylene blue (MB), indomethacin, atropine and propranolol, respectively.ResultsThe results showed that chloroform extract (CE) of Crinum amabile exhibited the highest vasorelaxation activity, and further fractionation of CE found that its F5 fraction exerted the strongest activity. An in-depth study on the mechanistic pathway revealed that the endothelium-dependent vasorelaxation induced by F5 fraction was primarily achieved through stimulation of prostaglandin (PGI2) production and partially associated with NO/cGMP activation pathway.ConclusionFindings from this study suggest that Crinum amabile can serve as a promising candidate for the discovery and development of the new vasorelaxant drug.

Antihypertensive effect of the stem bark aqueous extract of Garcinia lucida Vesque (Clusiaceae) in L-NAME-treated rats: Contribution of endothelium-dependent and -independent vasorelaxation

Garcinia lucida is used in Cameroonian folk medicine to handle a variety of ailments, including arterial hypertension. This study aimed at determining the phytochemical profile and the antihypertensive effect of the stem bark aqueous extract of G. lucida (AEGL). AEGL was subjected to LC-MS analysis, and its effect (75, 150, and 300 mg/kg/day; by gavage) was evaluated against Nω-nitro-L-arginine methyl ester (L-NAME; 40 mg/kg)-induced hypertension in adult male Wistar rats for four consecutive weeks. Blood pressure and heart rate were monitored weekly using tail-cuff plethysmography. The vasorelaxant effect of cumulative concentrations (3–10–30–100–300 μg/mL) of AEGL was examined on endothelium-intact and denuded thoracic aorta rings which were precontracted with KCl (90 mM) or norepinephrine (NE; 10−5 M), and in the absence or presence of L-NAME (10−4 M), indomethacin (10−5 M), methylene blue (10−6 M), tetraethylammonium (TEA, 5 × 10−6 M), glibenclamide (10 × 10−6 M) or propranolol (5 × 10−6 M). The influence of AEGL on the response to NE, KCl, and CaCl2 was also investigated. Six compounds, including Garcinia biflavonoids GB1 and GB2, were identified. AEGL prevented the development of hypertension (p < 0.01 and p < 0.001) without affecting the heart rate. AEGL induced a concentration-dependent relaxation of aortic rings precontracted with NE (EC50 = 7.915 μg/mL) that was significantly inhibited by the removal of the endothelium, L-NAME, or methylene blue (p < 0.05–0.001). Indomethacin, propranolol, TEA, and glibenclamide did not affect AEGL-evoked vasorelaxation. Preincubation of aortic rings with AEGL reduced the magnitude of contraction elicited by CaCl2 but did not alter that of KCl or NE. AEGL possesses an antihypertensive effect that is mediated by both endothelium-dependent and endothelium-independent mechanisms. The activation of the NO/sGC/cGMP pathway accounts for the endothelium-dependent vasorelaxation. These pharmacological effects of AEGL could be attributed to the presence of the Garcinia biflavonoids GB1 and GB2.

Vasodilator Responses of Perivascular Adipose Tissue-Derived Hydrogen Sulfide Stimulated with L-Cysteine in Pregnancy Hypertension-Induced Endothelial Dysfunction in Rats.

Endothelium-derived nitric oxide (NO)-induced vasodilation is impaired in pregnancy hypertension. However, the role of perivascular adipose tissue (PVAT)-derived hydrogen sulfide (H2S), as an alternative for counteracting vascular dysfunction, is incompletely clear in hypertensive disorders of pregnancy. Therefore, PVAT-derived H2S-induced vasodilation was investigated in pregnancy hypertension-induced endothelial dysfunction. Non-pregnant (Non-Preg) and pregnant (Preg) rats were submitted (or not) to the deoxycorticosterone (DOCA)-salt protocol and assigned as follows (n = 10/group): Non-Preg, Non-Preg+DOCA, Preg, and Preg+DOCA groups. Systolic blood pressure (SBP), angiogenesis-related factors, determinant levels of H2S (PbS), NO (NOx), and oxidative stress (MDA) were assessed. Vascular changes were recorded in thoracic aortas with PVAT and endothelium (intact and removed layers). Vasorelaxation responses to the substrate (L-cysteine) for the H2S-producing enzyme cystathionine-γ-lyase (CSE) were examined in the absence and presence of CSE-inhibitor DL-propargylglycine (PAG) in thoracic aorta rings pre-incubated with cofactor for CSE (pyridoxal-5 phosphate: PLP) and pre-contracted with phenylephrine. Hypertension was only found in the Preg+DOCA group. Preg+DOCA rats showed angiogenic imbalances and increased levels of MDA. PbS, but not NOx, showed increased levels in the Preg+DOCA group. Pre-incubation with PLP and L-cysteine elevated determinants of H2S in PVAT and placentas of Preg-DOCA rats, whereas no changes were found in the aortas without PVAT. Aortas of Preg-DOCA rats showed that PVAT-derived H2S-dependent vasodilation was greater compared to endothelium-derived H2S, whereas PAG blocked these responses. PVAT-derived H2S endogenously stimulated with the amino acid L-cysteine may be an alternative to induce vasorelaxation in endothelial dysfunction related to pregnancy hypertension.

Effects of gold nanoparticles phytoreduced with Cornus mas L. extract on the aorta wall function in rats with hyperlipid diet - a study on isolated aortic rings.

Vascular reactivity may be influenced by the dysfunction of the perivascular adipose tissue (PVAT) that occurs after a prolonged high fat diet (HFD). The aim of this study was to investigate the vascular responses in rats with prolonged HFD after the administration of Cornus mas L. extract as a simple solution or as a reducing agent for gold nanoparticles (AuNPs). Sprague-Dawley adult female rats (21 animals) were randomly allocated into three groups (n=7) and received for 9 months hyperlipid diet, the last month with treatment administered through oral gavage, 0.5 mL/day of solution as follows: HFD group - 0.9% saline solution, HFD+CM group - Cornus mas L. extract (0.158 mg/mL polyphenols), HFD+AuNPsCM group - gold nanoparticles phytoreduced with Cornus mas L. extract (AuNPsCM, 260 μg Au/kg/day). The Control group of rats (n=7) was fed with standard diet and in the last month received 0.9% saline solution as treatment. At the end of the experiment, the rats' descending aortas were collected and were used to investigate the aorta wall responses to vasoconstrictor (phenylephrine) and vasodilator (acetylcholine) substances added in tissue bath. AuNPsCM administration, compared to Control and HFD groups, increased the contraction and reduced the relaxation in aorta rings of rats with prolonged high-fat diet. The simple solution of Cornus mas L. extract produced contractile responses similar to those recorded in the Control group, at lower levels than in HFD group, and relaxation responses significantly decreased in comparison with Control group and significant increased when compared to HFD group. Cornus mas L. extract administered as simple solution improved the aorta functions, while AuNPsCM solution enhanced the existed aorta wall modifications occurred after prolonged HFD, altering the vessel wall responses.

Elsholtzia ciliata Essential Oil Exhibits a Smooth Muscle Relaxant Effect.

A recent in vivo study in pigs demonstrated the hypotensive properties of essential oil extracted from the blossoming plant Elsholtzia ciliata. This study was designed to examine the effect of E. ciliata essential oil (EO) on smooth muscle contraction. Tension measurements were performed on prostate strips and intact aortic rings isolated from rats. Results showed that EO caused a concentration-dependent reduction in phenylephrine-induced contraction of both the prostate and aorta, with a more pronounced inhibitory effect in the prostate. The IC50 of EO for the prostate was 0.24 ± 0.03 µL/mL (n = 10) and for the aorta was 0.72 ± 0.11 µL/mL (n = 4, p < 0.05 vs. prostate). The chromatographic analysis identified elsholtzia ketone (10.64%) and dehydroelsholtzia ketone (86.23%) as the predominant compounds in the tested EO. Since both compounds feature a furan ring within their molecular structure, other furan ring-containing compounds, 2-acetylfuran (2AF) and 5-methylfurfural (5MFF), were examined. For the first time, our study demonstrated the relaxant effects of 2AF and 5MFF on smooth muscles. Further, results showed that EO, 2AF, and 5MFF altered the responsiveness of prostate smooth muscle cells to phenylephrine. Under control conditions, the EC50 of phenylephrine was 0.18 ± 0.03 µM (n = 5), while in the presence of EO, 2AF, or 5MFF, the EC50 values were 0.81 ± 0.3 µM (n = 5), 0.89 ± 0.11 µM (n = 5), and 0.69 ± 0.23 µM (n = 4), respectively, p < 0.05 vs. control. Analysis of the affinity of EO for α1-adrenergic receptors in the prostate suggested that EO at a certain range of concentrations has a competitive antagonistic effect on α1-adrenergic receptors. In conclusion, EO elicits a relaxant effect on smooth muscles which may be related to the inhibition of α1-adrenoreceptors.

Glycation of fibronectin impairs angiopoietin-1/Tie-2 signaling through uncoupling Tie-2-α5β1 integrin crosstalk

The dysfunction of angiopoietin-1 (Ang-1)/Tie-2 signaling pathways has been implicated in diabetic complications. However, the underlying molecular mechanisms remain unclear. Fibronectin (FN) is thought to have an important role in regulating Ang-1/Tie-2 signaling activation. But no previous study has investigated the effects of FN glycation on Ang-1/Tie-2 signaling. In the present study, FN was glycated by methylglyoxal (MGO) to investigate whether the glycation of FN contributes to diabetes-induced Ang-1/Tie-2 signaling impairment and to understand the molecular mechanisms involved. The results demonstrated that MGO-glycated FN significantly impaired Ang-1-evoked phosphorylation of Tie-2 and Akt, Ang-1-induced endothelial cell migration and tube formation and Ang-1-mediated cell survival. The glycation of FN also inhibited the binding of α5β1 integrin to Tie-2. Moreover, FN was remarkably modified by AGEs in aortae derived from db/db mice, indicating the glycation of FN in vivo. Ang-1-induced aortic ring vessel outgrowth and Ang-1-mediated cell survival were also both significantly inhibited in aortae from db/db mice compared to that from the wild type littermates. Moreover, FN, rather than glycated FN partly restored aortic ring angiogenesis in db/db mice, indicating that the angiogenesis defect in the db/db mice are due to FN glycation. Collectively, the results in the present study suggest that the glycation of FN impairs Ang-1/Tie-2 signaling pathway by uncoupling Tie-2-α5β1 integrin crosstalk. This may provide a mechanism for Ang-1/Tie-2 signaling dysfunction and angiogenesis failure in diabetic ischaemic diseases.

Studying Angiogenesis Using Matrigel In Vitro and In Vivo.

Angiogenesis plays a critical role in physiology and pathophysiology of the human body; hence, it is important to explore the methods to study angiogenesis under in vitro and in vivo settings. Here, we describe three different methods to assess angiogenesis using Matrigel: an in vitro two- or three-dimensional (2D/3D) tube formation or angiogenesis assay using endothelial cells with growth factor supplemented Matrigel, an ex vivo sprouting angiogenesis assay embedding aortic rings in the Matrigel, and finally, Matrigel plug assays wherein Matrigels are implanted into the flanks of mice to assess the recruitment of endothelial cells to form new blood vessels in vivo.

Synthesis of Ethyl Methyl 4-aryl-1,4-dihydropyridine-3,5-dicarboxylates as Potential Calcium Channel Blockers for Hypertension

Aim: Several new dihydropyridine-based calcium channel blockers have been synthesized and pharmacologically evaluated for the treatment of hypertension Background: Dihydropyridines constitute an important class of calcium channel blockers (CCBs) due to their high potency, wide heterogeneity and tremendous biological usefulness. As a follow-up to our previous studies on 4-aryl-1,4-dihydropyridines as calcium channel blockers for the treatment of hypertension, four new series of methyl ethyl ester substituted 1,4-dihydropyridines are reported. Objectives: The aim of the work was to study the effects of unsymmetrical ester substitutions on calcium channel blocking activity of dihydropyridines (DHPs) while retaining the aminoalkoxy side chain at various positions of the 4-aryl ring. The type and location of the substituents on the 4-aryl ring have been extensively explored to study the structure-activity relationship (SAR) in this series of dihydropyridines as calcium channel blockers. Methodology: The target DHPs were synthesized using modified Hantzsch condensation and further derivatization. The compounds were screened for their inhibitory potential against L-type calcium channels at a single concentration of 10 μM on NG108-15 cells (Neuroblastoma X Glioma). The most potent DHP 12 was also tested for its vasodilatory activity using rat thoracic aortic rings precontracted with KCl (30 mM) and in vivo antihypertensive activity in rats using the tail-cuff method. Results: The newly synthesized DHPs displayed diversified calcium channel blocking activity with compounds 1e, 1h, 2d, 2f, 2h, 6, 9, 11, 12 and 14, producing more than 50% inhibition of veratridine response. 3-imidazolylpropoxy substituted analogue 12 turned out to be the most potent compound of the four series of compounds and produced fairly higher inhibition (78.6%) of veratridine response in comparison to nifedipine (70%) at 10 μM. In addition, compound 12 produced potent vasodilatory and antihypertensive properties. Conclusion: Both location of the side chain and the type of substituent on methyl ethyl ester substituted 4-aryl ring affected the response of dihydropyridine derivatives towards L-type calcium channels.

Autotaxin-lysophosphatidic acid receptor 5 axis evokes endothelial dysfunction via reactive oxygen species signaling.

Lysophosphatidylcholine (LPC) is a bioactive lipid that has been shown to attenuate endothelium-dependent vasorelaxation contributing to endothelial dysfunction; however, the underlying mechanisms are not well understood. In this study, we investigated the molecular mechanisms involved in the development of LPC-evoked impairment of endothelium-dependent vasorelaxation. In aortic rings isolated from wild-type (WT) mice, a 20-min exposure to LPC significantly reduced the acetylcholine chloride (ACh)-induced vasorelaxation indicating the impairment of normal endothelial function. Interestingly, pharmacological inhibition of autotaxin (ATX) by GLPG1690 partially reversed the endothelial dysfunction, suggesting that lysophosphatidic acid (LPA) derived from LPC may be involved in the effect. Therefore, the effect of LPC was also tested in aortic rings isolated from different LPA receptor knock-out (KO) mice. LPC evoked a marked reduction in ACh-dependent vasorelaxation in Lpar1, Lpar2, and Lpar4 KO, but its effect was significantly attenuated in Lpar5 KO vessels. Furthermore, addition of superoxide dismutase reduced the LPC-induced endothelial dysfunction in WT but not in the Lpar5 KO mice. In addition, LPC increased H2O2 release from WT vessels, which was significantly reduced in Lpar5 KO vessels. Our findings indicate that the ATX-LPA-LPA5 receptor axis is involved in the development of LPC-induced impairment of endothelium-dependent vasorelaxation via LPA5 receptor-mediated reactive oxygen species production. Taken together, in this study, we identified a new pathway contributing to the development of LPC-induced endothelial dysfunction.

B-245 Applicability of metagenomic Next-Generation Sequencing (mNGS) in challenging infectious diseases in a tertiary hospital

Abstract Background Infectious diseases caused by rare pathogens or with unusual presentations pose a diagnostic challenge. Traditional microbiologic tests can be time-consuming, labor-intensive and have limited sensitivity for some organisms. Plasma metagenomic Next-Generation Sequencing (mNGS) detects whole microbial genetic material and detects even unsuspected organisms. We present three cases of challenging infectious diseases and discuss the applicability of mNGS in different scenarios. Methods Plasma NGS was performed at Karius, Inc. (Redwood City, CA, USA). Patient data was collected from hospital and laboratory electronic records. Results Case 1: An 8-year-old female with sickle-cell anemia developed a persistent daily fever two weeks after recovery from sepsis due to Streptococcus pyogenes. Clinical exam was normal and investigation was negative (blood cultures, echocardiogram, thoracic and abdominal CT scans and bone scintigraphy). Two weeks later mNGS was performed, which came out positive for Cytomegalovirus. As patient became afebrile in 48 h and the viral burden was low, she could be safely discharged. Case 2: A 43-year-old male with prosthetic aortic valve and an intraluminal aortic ring had a year-long history of fatigue, weight loss and hypoalbuminemia. CT scans showed ground-glass infiltrates and enlarged mediastinal lymph nodes. Empirical treatment for tuberculosis was ineffective. A year later, he developed hepatosplenomegaly, fever and pancytopenia. Blood cultures, bone marrow biopsy and serologies (HIV, hepatitis B/C, syphilis, brucellosis, bartonellosis, leishmaniasis) were negative. Cardiac surgery found no apparent signs of endocarditis and the prosthetic aortic valve biopsy revealed only an inflammatory infiltrate. A new CT scan showed thickened intraluminal aortic ring with aortic pseudoaneurysms and splenomegaly with splenic infarction. A blood sample was then collected for mNGS and liver biopsy and splenectomy were performed. However, surgery complicated with hemodynamic instability, renal and liver failure and the patient died in less than 24 h. Two days later, mNGS came out positive for Coxiella burnetti. Case 3: A 45-year-old female with relapsed AML treating a chronic disseminated candidiasis with micafungin for 3 months had persistent liver and splenic nodules and new pulmonary nodules on the CT scan. In the following three months after chemotherapy (Gilteritinib), she developed multiple episodes of febrile neutropenia, some without microbiological documentation, leading to multiple courses of antibiotic treatment and a shift to liposomal amphotericin B. After clinical improvement and bone marrow recovery, liposomal amphotericin B was replaced by isavuconazole. A negative mNGS result allowed antifungal treatment to be safely discontinued, avoiding six months of unnecessary antifungal treatment. Conclusion We summarize three different scenarios of mNGS applications. In common, patients were submitted to multiple laboratory and image testing and received large doses of empirical antimicrobials due to lack of a precise diagnosis. In two cases, mNGS was diagnostic, shortened hospital stay and reduced overall costs. In case 2, the patient’s death might have been prevented if mNGS had been performed earlier. Vulnerable hospitalized patients with a broad spectrum of diagnostic possibilities, in whom sequential diagnostic tests could delay adequate therapy and cause significant adverse effects, could greatly benefit from mNGS when performed in a timely manner.

COMPUTATIONAL MODELING OF A LAYERED AORTIC MEDIAL WALL CONSIDERING EFFECTIVE RESIDUAL STRESSES

We previously developed a simplified finite element (FE) “unit” model to reproduce the mechanical interaction between the smooth muscle layer and elastic lamina (EL) in the aortic media. Nevertheless, whether this simplified FE model can represent the structure of a real medial wall and whether its modeling technique can help in developing a highly sophisticated and structure-based aortic FE model should be determined. Therefore, this study aimed to computationally represent EL buckling in the aortic medial ring at an unloaded state based on the integrated unit models and reproduce transmural variations in EL waviness across the vascular wall. We confirmed that the inner and outer layers of the medial wall were relatively subjected to compressive and tensile residual stresses, respectively, at the unloaded state, implying that the ring model will open spontaneously when it is radially cut. In addition, the residual stresses computed under such a stress-free condition were comparable to the analytically estimated values, partially supporting the validity of our modeling approach. Although further study is still required, the information obtained in this study will greatly improve the understanding of basic aortic physiology and pathophysiology and provide a basis for performing more sophisticated computational modeling of the aortic wall.

Computational Modeling of an Aortic Medial Wall: Effect of Residual Stresses on a Mechanical Behavior of the Aortic Ring

Abstract The aorta is the largest artery in an animal body and is an important organ in the pulsatile flow regulation from the left ventricle. The mechanical and structural characteristics of the aortic media, which are primarily composed of smooth muscle cell layers and elastic laminae (ELs), have profound effects on the physiology and pathophysiology of the aorta. However, many aspects of the aortic tissue remain unknown due to the inherent layered wall structure and the regionally varying residual stresses. This study aimed to computationally represent EL buckling in the aortic medial ring at the unloaded state and reproduce the transmural variation in residual stresses and EL waviness across the vascular wall. A multi-objective optimization technique was applied to a series of simulations with the “unit” structure to obtain an idealized stress distribution throughout the aortic wall thickness. Hence, an appropriate boundary condition given to an initial reference configuration of the aortic ring was successfully identified. As a result, the average “idealized” residual stresses of smooth muscle cell layer and EL were on the order of 20 and −80 kPa, respectively, while EL waviness was ∼1.01 in the unloaded state. Further, it was verified that the ring model with a radial cut will open spontaneously when the inner and outer layers of the medial wall are subjected to relative compressive and tensile residual stresses, respectively, in the unloaded state.