Anticontractile Effect Research Articles

Impact of the local renin–angiotensin system in perivascular adipose tissue on vascular health and disease

Perivascular adipose tissue (PVAT) is found locally around blood vessels. It has the ability to release vasoactive chemicals, such as factors that relax and contract blood vessels. PVAT is now recognized as an endocrine organ with metabolic activity and as a “protagonist” for maintaining vascular homeostasis. Angiotensin II, a powerful vasoconstrictor of the renin–angiotensin system (RAS) that can increase blood pressure and vascular tone, is produced locally by PVAT. To mitigate the multiple vascular effects of angiotensin II, PVAT also generates molecules such as angiotensin (1–7), adiponectin, and nitric oxide. Reactive oxygen species and proinflammatory cytokines are produced in greater amounts when PVAT-mediated angiotensin II is present, resulting in endothelial dysfunction, inflammation, atherosclerosis, and other vascular disorders. The anticontractile and procontractile nature of PVAT is frequently disrupted in obese individuals, which increases the production of angiotensin II and decreases the production of anti-inflammatory and vasodilatory factors. These changes in turn exacerbate vascular inflammation, hypertension, and atherosclerosis. PVAT, which is crucial for maintaining vascular homeostasis, loses its anticontractile effect in obesity due to adipocyte hypertrophy, inflammation, and oxidative stress, exacerbating endothelial dysfunction. Overactive RAS in PVAT facilitates the migration and proliferation of vascular smooth muscle cells and atherosclerotic plaques, both of which accelerate the development of atherosclerosis. Targeting PVAT and the local RAS can offer therapeutic benefits in treating hypertension, atherosclerosis, and other vascular diseases. This review highlights the scientific underpinnings of the function of PVAT in regulating the autocrine and paracrine activities of vascular RAS constituents.

Perivascular Adipose Tissue Becomes Pro-Contractile and Remodels in an IL10-/- Colitis Model of Inflammatory Bowel Disease.

Inflammatory Bowel Diseases (IBDs) are associated with aberrant immune function, widespread inflammation, and altered intestinal blood flow. Perivascular adipose tissue (PVAT) surrounding the mesenteric vasculature can modulate vascular function and control the local immune cell population, but its structure and function have never been investigated in IBD. We used an IL10-/- mouse model of colitis that shares features with human IBD to test the hypothesis that IBD is associated with (1) impaired ability of PVAT to dilate mesenteric arteries and (2) changes in PVAT resident adipocyte and immune cell populations. Pressure myography and electrical field stimulation of isolated mesenteric arteries show that PVAT not only loses its anti-contractile effect but becomes pro-contractile in IBD. Quantitative immunohistochemistry and confocal imaging studies found significant adipocyte hyperplasia and increased PVAT leukocytes, particularly macrophages, in IBD. PCR arrays suggest that these changes occur alongside the altered cytokine and chemokine gene expression associated with altered NF-κB signaling. Collectively, these results show that the accumulation of macrophages in PVAT during IBD pathogenesis may lead to local inflammation, which ultimately contributes to increased arterial constriction and decreased intestinal blood flow with IBD.

"Evaluation of the effects of pioglitazone on perivascular adipose tissue function, properties and structure in a rat model of type-2 diabetes."

Perivascular adipose tissue (PVAT) plays an important role in many physiological and pathological processes, such as regulation of vascular tone. The aim of this study is to evaluate the effects of pioglitazone on functional, structural, and biochemical properties of PVAT in an experimental model of type-2 diabetes (T2DM). T2DM was induced by high-fat-diet/low-dose-streptozotocin (HFD/STZ) in rats, and pioglitazone (20mg/kg/p.o.) was administered for 6 weeks. Changes in biochemical parameters, PVAT-mass, vascular-reactivity in thoracic-aorta as well as PVAT adipocytokine and PPARG-expression levels, and histopathology were evaluated. Pioglitazone administration improved blood glucose and lipid profiles in T2DM. Pioglitazone did not change the anticontractile effect of PVAT on aortic contractile reactivity and besides, had no influence on endothelium-dependent and -independent relaxation responses. Pioglitazone administration increased PVAT-mass and TNF-α levels while adiponectin, leptin, and IL-6 levels were unchanged. Also, a prominent increase was observed in PPARG-expression in T2DM-Pio group. Moreover, pioglitazone decreased liver steatosis, aortic wall thickening and myocardial damage whereas increased adipocyte size and adiposity in PVAT. Overall, pioglitazone treatment changed the mass and in part the inflammatory profile of PVAT but did not modify vasoreactivity in T2DM. This study provides novel findings in relationship with the adipogenic effect of pioglitazone and PVAT function.

A Skeletal Muscle-Mediated Anticontractile Response on Vascular Tone: Unraveling the Lactate-AMPK-NOS1 Pathway in Femoral Arteries.

The regulation of vascular tone by perivascular tissues is a complex interplay of various paracrine factors. Here, we investigate the anti-contractile effect of skeletal muscle surrounding the femoral and carotid arteries and its underlying mechanisms. Using male and female Wistar rats, we demonstrated that serotonin, phenylephrine, and U-46619 induced a concentration-dependent vasoconstrictor response in femoral artery rings. Interestingly, this response was diminished in the presence of surrounding femoral skeletal muscle, irrespective of sex. No anti-contractile effect was observed when the carotid artery was exposed to its surrounding skeletal muscle. The observed effect in the femoral artery persisted even in the absence of endothelium and when the muscle was detached from the artery. Furthermore, the skeletal muscle surrounding the femoral artery was able to promote an anti-contractile effect in three other vascular beds (basilar, mesenteric, and carotid arteries). Using inhibitors of lactate dehydrogenase and the 1/4 monocarboxylate transporter, we confirmed the involvement of lactate, as both inhibitors were able to abolish the anti-contractile effect. However, lactate did not directly promote vasodilation; rather, it exerted its effect by activating 5' AMP-activated protein kinase (AMPK) and neuronal nitric oxide synthase (NOS1) in the skeletal muscle. Accordingly, Nω-propyl L-arginine, a specific inhibitor of NOS1, prevented the anti-contractile effect, as well as lactate-induced phosphorylation of NOS1 at the stimulatory serine site (1417) in primary skeletal muscle cells. Phosphorylation of NOS1 was reduced in the presence of Bay-3827, a selective AMPK inhibitor. In conclusion, femoral artery-associated skeletal muscle is a potent paracrine and endocrine organ that influences vascular tone in both sexes. Mechanistically, the anti-contractile effect involves muscle fiber type and/or its anatomical location but not the type of artery or its related vascular endothelium. Finally, the femoral artery anti-contractile effect is mediated by the lactate-AMPK-phospho-NOS1Ser1417-NO signaling axis.

Endothelin-1 down-regulates nuclear factor erythroid 2-related factor-2 and contributes to perivascular adipose tissue dysfunction in obesity.

Perivascular adipose tissue (PVAT) negatively regulates vascular muscle contraction. However, in the context of obesity, the PVAT releases vasoconstrictor substances that detrimentally affect vascular function. A pivotal player in this scenario is the peptide endothelin-1 (ET-1), which induces oxidative stress and disrupts vascular function. The present study postulates that obesity augments ET-1 production in the PVAT, decreases the function of the nuclear factor erythroid 2-related factor-2 (Nrf2) transcription factor, further increasing reactive oxygen species (ROS) generation, culminating in PVAT dysfunction. Male C57BL/6 mice were fed either a standard or a high-fat diet for 16 weeks. Mice were also treated with saline or a daily dose of 100 mg·kg-1 of the ETA and ETB receptor antagonist Bosentan, for 7 days. Vascular function was evaluated in thoracic aortic rings, with and without PVAT. Mechanistic studies utilized PVAT from all groups and cultured WT-1 mouse brown adipocytes. PVAT from obese mice exhibited increased ET-1 production, increased ECE1 and ETA gene expression, loss of the anticontractile effect, as well as increased ROS production, decreased Nrf2 activity, and downregulated expression of Nrf2-targeted antioxidant genes. PVAT of obese mice also exhibited increased expression of Tyr216-phosphorylated-GSK3β and KEAP1, but not BACH1 - negative Nrf2 regulators. Bosentan treatment reversed all these effects. Similarly, ET-1 increased ROS generation and decreased Nrf2 activity in brown adipocytes, events mitigated by BQ123 (ETA receptor antagonist). These findings place ET-1 as a major contributor to PVAT dysfunction in obesity and highlight that pharmacological control of ET-1 effects restores PVAT's cardiovascular protective role.

Abstract P153: The Role of Lipoprotein Lipase Activation in Vascular Aging

Lipoprotein metabolism plays a role in cardiovascular diseases and becomes impaired with aging. Angiopoietin-like proteins (ANGPTLs) regulate lipoprotein lipase (LPL) and endothelial lipase (EL), key hydrolases in triglyceride catabolism. We hypothesized that ANGPTL3 and ANGPTL4 would be elevated in aging and that the response to LPL activation would be impaired in mesenteric resistance arteries (MRAs) from old rats. To assess this, MRAs were isolated from 3 and 16-month-old male and female Fischer344 rats and mounted on wire myographs. Concentration-response curves (CRC) to phenylephrine (PE, 10nM-100μM), Ca 2+ channel agonist Bay-K8644 (10nM-30nM), and acetylcholine (ACh, 0.1nM-100uM) were performed with or without LPL activator, NO-1886 (10uM and 50uM). Protein expression was assessed by Western blot. We show for the first time that circulating ANGPTL3 (young: 1.5±0.8 vs old: 5±0.7) and ANGPTL4 (young: 1.7±0.3 vs old: 2.5±0.5) are increased in aging. In MRAs from young rats, NO-1886 attenuated PE-induced contraction in males (Emax; vehicle: 106±3 vs NO-1886 10uM: 86 ± 5* vs NO-1886 50uM: 69±8*, p<0.05) and females (Emax; vehicle: 104±4 vs NO-1886 10uM: 91±5* vs NO-1886 50uM: 75±8*, p<0.05). While 16-month-old males presented a similar reduction in contraction (Emax; vehicle: 105±6 vs NO-1886 10uM: 88±11* vs NO-1886 50uM: 73±17*, p<0.05), in females only 50uM showed a significant anti-contractile effect in a sex-dependent manner (Emax; vehicle: 100±7 vs NO-1886 10uM: 95±7 vs NO-1886 50uM: 83±22*, p<0.05). CRC to bay-K8644 showed decreased contraction after NO-1886 incubation (Emax; vehicle: 16±8 vs NO-1886 50uM: 5±3) indicating that L-type Ca 2+ channel Ca 2+ influx isn’t involved in NO-1886’s anti-contractile effect. NO-1886 incubation did not change the maximal ACh response in young rat MRAs, but a rightward shift in the curve was seen in both sexes. As expected, MRAs from old males (Emax; young: 97±2 vs old: 86±7) and females (Emax; young: 95±2 vs old: 92±6) had decreased maximal relaxation to ACh, compared to young rats. Interestingly, in old rats NO-1886 induced further impaired relaxation to ACh in males (Emax; vehicle: 86±7 vs NO-1886 10uM: 78±14) and females (Emax; vehicle: 92±6 vs NO-1886 10uM: 77±22). Together, this data suggests (1) ANGPTL3 and ANGPTL4 are increased in old rats, (2) LPL/EL activity diminished with age in females, but not males, and (3) while NO-1886 exerts an anti-contractile effect, it can also induce endothelial dysfunction.

Abstract 12: Deficiency of Progranulin Decreases Mitochondrial Function and Induces a Whitening Phenotype in Perivascular Adipose Tissue, Suppressing Its Anti-Contractile Effects

Perivascular adipose tissue (PVAT) is recognized as an endocrine organ that secretes a variety of adipokines, which negatively regulate vascular contraction. Progranulin (PGRN), a glycoprotein encoded by the GRN gene, is highly expressed in adipocytes, and is implicated in inflammation, cellular proliferation, and repair mechanisms. The relationship between PGRN and PVAT remains unclear. We hypothesized that the lack of PGRN negatively affects PVAT quality. We used male C57BL/6J wild-type (WT) and global PGRN knockout (KO) mice, aged 10-12 weeks. Energy expenditure was analyzed via the Comprehensive Lab Animal Monitoring System (CLAMS). Vascular function was studied in endothelium-intact aortae with PVAT [PVAT(+)] and without PVAT [PVAT(-)]. Additionally, 3T3-L1 cells were used to evaluate the molecular mechanisms. The KO mice showed a decreased respiratory exchange ratio (RER) and a whitening phenotype of PVAT, which was accompanied by a loss of anti-contractile effects [(mN) WT_PVAT(-): 5.2±0.3 vs PVAT(+): 3.4±0.5*, *P<0.05 and KO_PVAT(-): 6.1±0.7 vs KO_PVAT(+): 5.7±0.4]. Additionally, PVAT from KO displayed a significant reduction in nitric oxide production [(RFU) WT_PVAT: 223.1± 12.3 vs KO_PVAT: 67.3±9.1*, *P<0.05] and endothelial NO synthase phosphorylation. Additionally, the lack of PGRN attenuated the expression of mitochondrial complexes [(AU) WT_PVAT: 1.3± 0.03 vs KO_PVAT: 0.6±0.06*, *P<0.05] measured by the OXPHOS cocktail antibody. Via high-resolution respirometry, we found that isolated mitochondria from KO_PVAT showed impaired succinate-driven respiration or complex II activity. To understand if the whitening phenotype of PVAT was leading to its dysfunction, we induced a browning phenotype of PVAT by treating the mice with a β3-agonist for 7 days (CL 316243, 1mg/kg/day). This treatment increased RER restored the PVAT phenotype, and improved PVAT anti-contractile effect and mitochondrial respiration. Using 3T3-L1 cells, we engineered the overexpression and knockdown of PGRN via lentivirus (LV) infection and siRNA, respectively. Suppression of PGRN increased mRNA of whitening markers (1.5-fold increase vs scramble siRNA), while overexpression elevated mRNA of browning and mitochondrial markers (1.3-fold increase vs scramble LV). In summary, our findings reveal that PGRN is crucial for maintaining the phenotype and anti-contractile function of PVAT and highlight PGRN as a pharmacological target for vascular outcomes in cardiometabolic conditions.

Abstract P448: Follistatin Improves Vascular Function by Regulating Perivascular Adipose Tissue in Essential Hypertension

Introduction: Essential hypertension is characterized by resistance artery remodeling induced by oxidative stress. Most vessels are surrounded by perivascular adipose tissue (PVAT) which regulates vascular tone via release of vasoactive substances. In physiological conditions, PVAT induces an anticontractile effect. In pathological conditions such as hypertension, PVAT exhibit increased oxidative stress resulting in augmented contraction and reduced relaxation. Follistatin, an antioxidant glycoprotein, has been shown to induce adipose tissue browning which is linked to improved vasorelaxation and BP. We hypothesize that follistatin, through ROS inhibition and PVAT browning, lowers BP and improves vessel function in a model of essential hypertension. Methods: Spontaneously hypertensive rats (SHR) were treated with vehicle or follistatin every other day for 8 weeks. Wistar Kyoto (WKY) rats served as normotensive controls. BP was measured weekly by radiotelemetry. Mesenteric arteries and PVAT were used. KCl-induced smooth muscle contraction was assessed using wire myography. ROS was measured by DHE (dihydroethidium) staining. Vasodilator nitric oxide (NO) bioavailability in PVAT was measured using DAF-2 FM. Protein expression of markers for ROS or PVAT browning was measured by immunohistochemistry. Results: Follistatin significantly lowered BP in SHRs and restored anticontractile effect of PVAT. Increased ROS in SHR vessels and PVAT were also inhibited. Follistatin inhibited SHR PVAT-induced vascular oxidative stress. SHR PVAT NO bioavailability was increased by acute follistatin treatment via ROS inhibition. Follistatin also increased expression of brown adipose tissue markers in SHR PVAT suggesting PVAT browning. Limitations: Above studies do not confirm whether PVAT pathology causes hypertension in this model. Vascular dysfunction is an independent risk factor for CVD and our studies do not yet consider effects of follistatin on end-organ damage. Conclusions: Follistatin lowers BP in SHRs likely via improved vascular and perivascular structure and function. Specifically, follistatin inhibited perivascular ROS, increased NO and induced PVAT browning suggesting improved regulation of vascular function and thus, BP. Future work will utilize proteomic assays to identify novel mediators of follistatin effects on PVAT in the SHR.

P169 VEGF INHIBITION-INDUCED PARP OVERACTIVATION LEADS TO ENDOTHELIAL DYSFUNCTION AND INFLAMMATION: ROLE OF SIRTUIN 1 SIGNALLING

Hypertension is a common unwanted effect of VEGF inhibitors (VEGFi), which are used as anti-angiogenic drugs in cancer treatment. Clinical observations indicate that the magnitude of blood pressure elevation is lower in patients with cancer who are treated with combination VEGFi and olaparib (poly-ADP ribose polymerase[PARP] inhibitor[PARPi]), versus monotherapy. However, putative vascular mechanisms are still unknown. PARP plays a major role in the activation of TRPM2, a redox-sensitive Ca2+ channel associated with hypertension-induced vascular dysfunction, and sirtuin deacetylases activity, especially sirtuin 1 (SIRT1), which is involved in vascular homeostasis/diseases. Here we sought to determine whether VEGFi-induce oxidative stress and PARP activation lead to vascular dysfunction through disruption of SIRT1 signalling. Human aortic endothelial cells (HAEC) and mouse mesenteric arteries were studied. Cells were exposed to axitinib (VEGFi;1 μM) alone or in combination with olaparib (PARPi;1 μM) in the presence or absence of a SIRT1 activator (SRT1720;2 μM). Axitinib increased PARP activity in a ROS-dependent manner (au:[Veh] 0.31 vs. [Axi] 0.55; [Tiron+Axi] 0.38] whereas SIRT1 activity was reduced by VEGF inhibition (33760 vs. 23367), which was prevented by olaparib. Expression of acetyl-p53 (au: 0.17 vs. 0.35) was increased. SIRT1 activation decreased levels of MCP-1 and IL-6 and reduced mRNA expression of VCAM-1 and ICAM-1 in HAEC exposed to axitinib, which was accompanied by a reduction in monocyte adhesion to HAEC, as observed for olaparib. U46619- and ET-1-induced vasoconstriction were increased by axitinib (U4:101.2[Ct] vs. 141.4[Axi]-ET-1:122.6[Ct] vs. 152.5[Axi]), an effect not observed with axitinib plus olaparib. Pre-incubation with SRT1720 exacerbated the anti-contractile effects of olaparib. Axitinib impaired ACh-induced vasodilation (%70.5 vs. 34.8), which was blocked by olaparib and SRT1720. Phosphorylation of eNOS (Thr495) was increased in HAEC (au: 0.18 vs. 0.37) and restored by SRT1720. In conclusion, our findings show that VEGFi-induced PARP overactivation leads to endothelial dysfunction and inflammatory responses via disruption of SIRT1 signalling. We define a putative vasoprotective effect of olaparib that may ameliorate vascular injury induced by VEGFi during cancer treatment.

Obesity and anticontractile effects of adipose tissue in the regulation of aortic tone

Obesity and anticontractile effects of adipose tissue in the regulation of aortic tone

Exercise Enhances Anti-contractile Effects of PVAT Through Endogenous H2S in High-Fat Diet-Induced Obesity Hypertension.

Hydrogen sulfide (H2S) secreted by perivascular adipose tissue (PVAT) is a critical vasodilator, which might be involved during the pathogenesis of hypertension. The present study aimed to investigate the exact role of H2S on the regulation of PVAT anti-contraction by long-term exercise in obesity hypertension. After the establishment of obesity hypertension (24weeks) through a high-fat diet, male Sprague-Dawley rats were randomly assigned to control group (HC), exercise group (HE), cystathionine γ-lyase (CSE) blocking group (HCB), and exercise combined with CSE blocking group (HEB). Exercise and CSE inhibitor regimens were performed throughout 13weeks. After 13weeks of intervention, blood pressure was significantly decreased by long-term exercise (HC vs. HE, P < 0.05) but not by exercise combined with the CSE inhibitor regimen. Meanwhile, the CSE inhibitor significantly blocked the production of H2S in PVAT even after exercise (HE vs. HEB, P < 0.05). Furthermore, long-term exercise altered the expressions of voltage-dependent K+ (Kv) channel subunits 7 (KCNQs), which were diminished by CSE inhibition in mesenteric arteries. As for vascular tension assessment, after incubation with or without KCNQ opener (retigabine), the anti-contractile effect of PVAT (with or without transferred bath solution of PVAT) was significantly enhanced by long-term exercise and eliminated by the CSE inhibitor regimen (P < 0.05); KCNQ inhibitor (XE991) blunted this effect except for HE. These results collectively suggest that endogenous H2S is a strong regulator of the anti-contractile effect of PVAT in obesity hypertension by long-term exercise, and KCNQ in the resistance artery might be involved during this process but not the only target channel mediated by H2S.

Propagermanium as a Novel Therapeutic Approach for the Treatment of Endothelial Dysfunction in Type 2 Diabetes.

Propagermanium (PG) has immune modulating activity and anti-inflammatory properties. This work aimed to study the therapeutic efficacy of PG on endothelial and perivascular dysfunction associated with type 2 diabetes. Non-obese type 2 diabetic Goto-Kakizaki (GK) rats were divided into four groups: (1) the control group; (2) the group treated with 50 mg/kg PG; (3) the group fed a high-fat diet (GKHFD); and (4) the group of GKHFD treated with 50 mg/kg PG. PG was given orally for 3 months. Several in vivo parameters and endothelial function were studied in aortas with perivascular adipose tissue PVAT (+) or without PVAT (-). We also determined the vascular inflammation and levels of CD36 in PVAT. In diabetic GK rats, PG did not affect the lipid profile or the results of the intraperitoneal glucose tolerance test. Instead, it improved the fasting glucose levels (18%, p < 0.01), insulin resistance (32%, p < 0.05), endothelial function (33 and 25% in aortas mounted with (+) or without PVAT (-), p < 0.05), and restored the anticontractile effect of the perivascular adipose tissue by reducing its inflammation (56%, p < 0.05) and oxidative stress profile (55%, p < 0.05). Due to its anti-inflammatory characteristics, PG likely improved endothelial dysfunction and restored the perivascular adipose tissue's anticontractile properties.

Dynamic phenotypic shifts and M2 receptor downregulation in bladder smooth muscle cells induced by mirabegron.

Mirabegron is available for treatment of overactive bladder (OAB). However, mechanisms underlying symptom improvements and long-term effects on bladder smooth muscle cells are uncertain. Contractility and growth of bladder smooth muscle contribute to OAB, and depend on smooth muscle phenotypes, and on muscarinic receptor expression. Here, we examined prolonged exposure to mirabegron (20-48h) on phenotype markers, muscarinic receptor expression, and phenotype-dependent functions in human bladder smooth muscle cells (hBSMC). Expression of markers for contractile (calponin, MYH11) and proliferative (MYH10, vimentin) phenotypes, proliferation (Ki-67), and of muscarinic receptors were assessed by RT-PCR. Proliferation, viability, actin organization and contractions in cultured hBSMC were examined by EdU, CCK-8, phalloidin staining and matrix contraction assays. Calponin-1 mRNA decreased with 100nM and 150nM mirabegron applied for 20h (0.56-0.6 fold of controls). Decreases were resistant to the β3-AR antagonist L-748,337 (0.34-0.55 fold, 100-150nM, 20h). After 40h, decreases occured in the presence of L-748,337, but not without L-748,337. MYH11 mRNA increased with 150nM mirabegron (40h, 1.9 fold). This was partly preserved with L-748,337, but not observed after 20h mirabegron exposure. Vimentin mRNA reduced with 150nM mirabegron after 20h, but not after 40h, with and without L-748,337 (0.71-0.63 fold). MYH10 mRNA expression remained unaffected by mirabegron. Exposure to 150nM mirabegron increased Ki-67 mRNA after 20h in the presence of, but not without L-748,337, and after 40h without, but not with L-748,337. Proliferation rates and actin organization were stable with 50-150nM mirabegron (24h, 48h). Viability increased significantly after mirabegron exposure for 20h, and by trend after 40h, which was fully sensitive to L-748,337. M2 mRNA was reduced by 20h mirabegron, which was resistant to L-748,337. Carbachol (3µM) enhanced time-dependent contractions of hBSMC, which was inhibited by mirabegron (150nM) in late phases (24h), but not in early phases of contractions. Conclusion: Mirabegron induces dynamic phenotype alterations and M2 downregulation in hBSMC, which is paralleled by time-shifted anticontractile effects. Phenotype transitions may be involved in improvements of storage symptoms in OAB by mirabegron.

Egg white hydrolysate modulates the renin-angiotensin system in mesenteric perivascular adipose tissue in doca-salt hypertensive rats and restores its anticontractile ability

Perivascular adipose tissue (PVAT) regulates vascular tonus with an anticontractile effect, which may be dysfunctional in hypertension. An Egg White Hydrolysate (EWH), a bioactive food, restores endothelium dysfunction and reduces blood pressure levels in malignant hypertension. We aimed to evaluate whether dietary supplementation with EWH interferes with the PVAT function in the mesenteric resistance arteries (MRA) of DOCA-salt hypertensive animals and the mechanisms involved. Male rats were divided into 4 groups and treated for 8 weeks. For 4 weeks, DOCA-salt or vehicle-treated rats (SHAM) were induced, and after that, some rats were co-treated with DOCA-salt or vehicle plus EWH (1 g/kg/day) for 4 weeks more. MRA and/or their PVAT (mPVAT) were used for functional, molecular, and biochemical analysis. The anticontractile effect of mPVAT in response to norepinephrine (NE) was observed only in MRA rings with PVAT of the SHAM group, while this effect was abolished in DOCA-salt rings. The EWH treatment did not change the anticontractile effect of mPVAT in SHAM but partially restored it in DOCA-salt rats. Acute aliskiren incubation reduced NE-induced contraction only in MRA with PVAT of DOCA-salt rats. EWH prevented the overactivation of the renin levels and ACE activity in mPVAT of DOCA-salt rats; while did not change AT1R expression, but increased AT2R expression. In mPVAT, EWH blocked the increase of MDA, ROS and pro-inflammatory cytokines observed in DOCA-salt rats. EWH improved PVAT dysfunction in MRA of severe hypertension. This beneficial effect could be mediated by an ameliorated redox balance, inflammatory state, and RAS axis.

Sex-Specific Effects of Cholesteryl Ester Transfer Protein (CETP) on the Perivascular Adipose Tissue.

Cholesteryl ester transfer protein (CETP) increases the atherosclerosis risk by lowering HDL-cholesterol levels. It also exhibits tissue-specific effects independent of HDL. However, sexual dimorphism of CETP effects remains largely unexplored. Here, we hypothesized that CETP impacts the perivascular adipose tissue (PVAT) phenotype and function in a sex-specific manner. PVAT function, gene and protein expression, and morphology were examined in male and female transgenic mice expressing human or simian CETP and their non-transgenic counterparts (NTg). PVAT exerted its anticontractile effect in aortas from NTg males, NTg females, and CETP females, but not in CETP males. CETP male PVAT had reduced NO levels, decreased eNOS and phospho-eNOS levels, oxidative stress, increased NOX1 and 2, and decreased SOD2 and 3 expressions. In contrast, CETP-expressing female PVAT displayed increased NO and phospho-eNOS levels with unchanged NOX expression. NOX inhibition and the antioxidant tempol restored PVAT anticontractile function in CETP males. Ex vivo estrogen treatment also restored PVAT function in CETP males. Moreover, CETP males, but not female PVAT, show increased inflammatory markers. PVAT lipid content increased in CETP males but decreased in CETP females, while PVAT cholesterol content increased in CETP females. CETP male PVAT exhibited elevated leptin and reduced Prdm16 (brown adipocyte marker) expression. These findings highlight CETP sex-specific impact on PVAT. In males, CETP impaired PVAT anticontractile function, accompanied by oxidative stress, inflammation, and whitening. Conversely, in females, CETP expression increased NO levels, induced an anti-inflammatory phenotype, and preserved the anticontractile function. This study reveals sex-specific vascular dysfunction mediated by CETP.

Innervation of adipocytes is limited in mouse perivascular adipose tissue.

Perivascular adipose tissue (PVAT) regulates vascular tone by releasing anticontractile factors. These anticontractile factors are driven by processes downstream of adipocyte stimulation by norepinephrine; however, whether norepinephrine originates from neural innervation or other sources is unknown. The goal of this study was to test the hypothesis that neurons innervating PVAT provide the adrenergic drive to stimulate adipocytes in aortic and mesenteric perivascular adipose tissue (aPVAT and mPVAT), and white adipose tissue (WAT). Healthy male and female mice (8-13 wk) were used in all experiments. Expression of genes associated with synaptic transmission were quantified by qPCR and adipocyte activity in response to neurotransmitters and neuron depolarization was assessed in AdipoqCre+;GCaMP5g-tdTf/WT mice. Immunostaining, tissue clearing, and transgenic reporter lines were used to assess anatomical relationships between nerves and adipocytes. Although synaptic transmission component genes are expressed in adipose tissues (aPVAT, mPVAT, and WAT), strong nerve stimulation with electrical field stimulation does not significantly trigger calcium responses in adipocytes. However, norepinephrine consistently elicits strong calcium responses in adipocytes from all adipose tissues studied. Bethanechol induces minimal adipocyte responses. Imaging neural innervation using various techniques reveals that nerve fibers primarily run alongside blood vessels and rarely branch into the adipose tissue. Although nerve fibers are associated with blood vessels in adipose tissue, they demonstrate limited anatomical and functional interactions with adjacent adipocytes, challenging the concept of classical innervation. These findings dispute the significant involvement of neural input in regulating PVAT adipocyte function and emphasize alternative mechanisms governing adrenergic-driven anticontractile functions of PVAT.NEW & NOTEWORTHY This study challenges prevailing views on neural innervation in perivascular adipose tissue (PVAT) and its role in adrenergic-driven anticontractile effects on vasculature. Contrary to existing paradigms, limited anatomical and functional connections were found between PVAT nerve fibers and adipocytes, underscoring the importance of exploring alternative mechanistic pathways. Understanding the mechanisms involved in PVAT's anticontractile effects is critical for developing potential therapeutic interventions against dysregulated vascular tone, hypertension, and cardiovascular disease.

Vandetanib as a prospective anti-inflammatory and anti-contractile agent in asthma.

Background: Vandetanib is a small-molecule tyrosine kinase inhibitor. It exerts its therapeutic effects primarily in a range of lung cancers by inhibiting the vascular endothelial growth factor receptor 2. However, it remains unclear whether vandetanib has therapeutic benefits in other lung diseases, particularly asthma. The present study investigated the pioneering use of vandetanib in the treatment of asthma. Methods: In vivo experiments including establishment of an asthma model, measurement of airway resistance measurement and histological analysis were used primarily to confirm the anticontractile and anti-inflammatory effects of vandetanib, while in vitro experiments, including measurement of muscle tension and whole-cell patch-clamp recording, were used to explore the underlying molecular mechanism. Results: In vivo experiments in an asthmatic mouse model showed that vandetanib could significantly alleviate systemic inflammation and a range of airway pathological changes including hypersensitivity, hypersecretion and remodeling. Subsequent in vitro experiments showed that vandetanib was able to relax the precontracted rings of the mouse trachea via calcium mobilization which was regulated by specific ion channels including VDLCC, NSCC, NCX and K+ channels. Conclusions: Taken together, our study demonstrated that vandetanib has both anticontractile and anti-inflammatory properties in the treatment of asthma, which also suggests the feasibility of using vandetanib in the treatment of asthma by reducing abnormal airway contraction and systemic inflammation.

Beclin-1-Dependent Autophagy Preserves Perivascular Adipose Tissue Function and Suppresses Hypertension Development in Hyperaldosteronism

Hyperaldosteronism (HA), characterized by the independent overproduction of aldosterone (Aldo), leads to cardiovascular damage and perivascular adipose tissue (PVAT) dysfunction. Beclin-1 (Becn1) is a key protein regulating autophagy, a recycling process of unwanted components. Whether HA disturbs autophagic flux in PVAT via Becn1 is unknown. Thus, we hypothesize that Becn1-dependent autophagic flux will improve PVAT function and inhibit the genesis of hypertension (HTN) in HA. 10-12-weeks-old male C57BL/6J (WT) or Becn1 knock-in mice (Becn1Tg) mice were infused with aldosterone for 14 days (600ug/Kg/day via osmotic mini-pump). Vascular function was studied in PVAT-intact thoracic aortae and blood pressure was analyzed by radiotelemetry. Becn1Tg mice were protected from HA-induced HTN [mean blood pressure (mmHg) − before HA: 101.2±0.5 vs. after HA: 108.2±0.9]. HA disrupted PVAT autophagic flux characterized by accumulation of LC3A/B and p62 and reduction in Becn1 expression and activity. In terms of function, presence of PVAT decreased the contractile response in WT [PVAT (-): 137.2±1.9 vs. PVAT (+): 107.4±2.7, Emax (% KCl)], while HA induced loss of PVAT anti-contractile effect [PVAT (-): 159.9±2.9 vs. PVAT (+): 164.1±3.4]. Becn1Tg mice were protected from this effect. Furthermore, HA induced PVAT oxidative stress and inflammation, characterized by elevated TNF-α, IL-6, IL-1β, IL-17, and IFN-γ mRNA expression, and elevated reactive oxygen species (ROS), measured by lucigenin chemiluminescence. All these effects were prevented in Becn1Tg mice. Pharmacological induction of Becn1 activation, via TB-peptide (16mg/Kg/day for 7 days), improved PVAT function of WT mice with HA. To evaluate the molecular mechanisms, we treated brown adipocyte cells (BAC, WT1) with Aldo (100nM), which triggered a transient autophagic flux, depicted by an initial increase in LC3A/B (12 and 24 h), followed by a decrease at 48 and 96 h. Such effects were prevented by a selective mineralocorticoid receptor antagonist (Eplerenone, 1μM). Finally, Aldo induced BAC inflammation and oxidative stress, which were blunted by TB-peptide. In summary, our findings reveal that autophagy overactivation confers protection against HA-induced PVAT inflammation and dysfunction and HTN. Therefore, activation of Becn1 could be pharmacological tool to prevent HA-associated cardiovascular deleterious effects. FAPESP (2022/06639-2), NHLBI-R00 (R00HL14013903), AHA (CDA857268 and 23DIVSUP1069230), Vascular Medicine Institute, the Hemophilia Center of Western Pennsylvania Vitalant, and Children's Hospital of Pittsburgh of the UPMC Health System. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Macrophage-derived human resistin promotes perivascular adipose tissue dysfunction in experimental inflammatory arthritis

Cardiovascular disease (CVD) is the leading cause of death in rheumatoid arthritis (RA). Resistin is an adipokine that induces adipose tissue inflammation and activation of monocytes/macrophages via adenylate cyclase-associated protein-1 (CAP1). Resistin levels are increased in RA and might cause perivascular adipose tissue (PVAT) dysfunction, leading to vascular damage and CVD. This study aimed to investigate the role of resistin in promoting PVAT dysfunction by increasing local macrophage and inflammatory cytokines content in antigen-induced arthritis (AIA). Resistin pharmacological effects were assessed by using C57Bl/6J wild-type (WT) mice, humanized resistin mice expressing human resistin in monocytes-macrophages (hRTN+/-/-), and resistin knockout mice (RTN-/-) with AIA and respective controls. We investigated AIA disease activity and functional, cellular, and molecular parameters of the PVAT. Resistin did not contribute to AIA disease activity and its concentrations were augmented in the PVAT and plasma of WT AIA and hRTN+/-/- AIA animals. In vitro exposure of murine arteries to resistin impaired vascular function by decreasing the anti-contractile effect of PVAT. WT AIA mice and hRTN+/-/- AIA mice exhibited PVAT dysfunction and knockdown of resistin prevented it. Macrophage-derived cytokines, markers of types 1 and 2 macrophages, and CAP1 expression were increased in the PVAT of resistin humanized mice with AIA, but not in knockout mice for resistin. This study reveals that macrophage-derived resistin promotes PVAT inflammation and dysfunction regardless of AIA disease activity. Resistin might represent a translational target to reduce RA-driven vascular dysfunction and CVD.

Perinatal hypoxia weakens anticontractile influence of NO in rat arteries during early postnatal period.

Perinatal hypoxia affects a lot of neonates worldwide every year, however its effects on the functioning of systemic circulation are not clear yet. We aimed at investigation the effects of perinatal hypoxia on the second day of life on the functioning of the rat systemic vasculature in early postnatal period. 2-day-old male rat pups were exposed to normobaric hypoxia (8% O2, 92% N2) for 2 hours. At the 11-14 days cutaneous (saphenous) arteries were isolated and studied by wire myography and Western blotting. Hypoxia weakened the contribution of anticontractile influence of NO, but did not affect the contribution of Rho-kinase or Kv7 channels to the contraction to α1-adrenergic agonist methoxamine. The content of eNOS and protein kinase G were not altered by hypoxic conditions. Perinatal hypoxia in rats at the second day of life leads to the decrease of anticontractile effect of NO in the systemic arteries in early postnatal ontogenesis (at the age of 11-14 days). Decreased anticontractile effect of NO can be the reason for insufficient blood supply and represent a risk factor for the development of cardiovascular disorders. The mechanisms of perinatal hypoxia influences on systemic circulation are almost unknown. We have shown that perinatal hypoxia weakens anticontractile influence of nitric oxide in early postnatal period. The influence of perinatal hypoxia on systemic circulation should be taken into account during treatment of newborns suffered from the lack of oxygen.