Mechanisms of Vascular Inflammation and Potential Therapeutic Targets: A Position Paper From the ESH Working Group on Small Arteries

Inflammatory responses in small vessels play an important role in the development of cardiovascular diseases, including hypertension, stroke, and small vessel disease. This involves various complex molecular processes including oxidative stress, inflammasome activation, immune-mediated responses, and protein misfolding, which together contribute to microvascular damage. In addition, epigenetic factors, including DNA methylation, histone modifications, and microRNAs influence vascular inflammation and injury. These phenomena may be acquired during the aging process or due to environmental factors. Activation of proinflammatory signaling pathways and molecular events induce low-grade and chronic inflammation with consequent cardiovascular damage. Identifying mechanism-specific targets might provide opportunities in the development of novel therapeutic approaches. Monoclonal antibodies targeting inflammatory cytokines and epigenetic drugs, show promise in reducing microvascular inflammation and associated cardiovascular diseases. In this article, we provide a comprehensive discussion of the complex mechanisms underlying microvascular inflammation and offer insights into innovative therapeutic strategies that may ameliorate vascular injury in cardiovascular disease.

Immune and inflammatory mechanisms in hypertension

Hypertension is a global health problem, with >1.3 billion individuals with high blood pressure worldwide. In this Review, we present an inflammatory paradigm for hypertension, emphasizing the crucial roles of immune cells, cytokines and chemokines in disease initiation and progression. T cells, monocytes, macrophages, dendritic cells, B cells and natural killer cells are all implicated in hypertension. Neoantigens, the NLRP3 inflammasome and increased sympathetic outflow, as well as cytokines (including IL-6, IL-7, IL-15, IL-18 and IL-21) and a high-salt environment, can contribute to immune activation in hypertension. The activated immune cells migrate to target organs such as arteries (especially the perivascular fat and adventitia), kidneys, the heart and the brain, where they release effector cytokines that elevate blood pressure and cause vascular remodelling, renal damage, cardiac hypertrophy, cognitive impairment and dementia. IL-17 secreted by CD4+ T helper 17 cells and γδ T cells, and interferon-γ and tumour necrosis factor secreted by immunosenescent CD8+ T cells, exert crucial effector roles in hypertension, whereas IL-10 and regulatory T cells are protective. Effector mediators impair nitric oxide bioavailability, leading to endothelial dysfunction and increased vascular contractility. Inflammatory effector mediators also alter renal sodium and water balance and promote renal fibrosis. These mechanisms link hypertension with obesity, autoimmunity, periodontitis and COVID-19. A comprehensive understanding of the immune and inflammatory mechanisms of hypertension is crucial for safely and effectively translating the findings to clinical practice.

The importance of microvascular inflammation in ageing and age-related diseases: a position paper from the ESH working group on small arteries, section of microvascular inflammation

Microcirculation is pervasive and orchestrates a profound regulatory cross-talk with the surrounding tissue and organs. Similarly, it is one of the earliest biological systems targeted by environmental stressors and consequently involved in the development and progression of ageing and age-related disease. Microvascular dysfunction, if not targeted, leads to a steady derangement of the phenotype, which cumulates comorbidities and eventually results in a nonrescuable, very high-cardiovascular risk. Along the broad spectrum of pathologies, both shared and distinct molecular pathways and pathophysiological alteration are involved in the disruption of microvascular homeostasis, all pointing to microvascular inflammation as the putative primary culprit. This position paper explores the presence and the detrimental contribution of microvascular inflammation across the whole spectrum of chronic age-related diseases, which characterise the 21st-century healthcare landscape. The manuscript aims to strongly affirm the centrality of microvascular inflammation by recapitulating the current evidence and providing a clear synoptic view of the whole cardiometabolic derangement. Indeed, there is an urgent need for further mechanistic exploration to identify clear, very early or disease-specific molecular targets to provide an effective therapeutic strategy against the otherwise unstoppable rising prevalence of age-related diseases.

Single cell atlas of cd45+ cells in angiotensin II-induced hypertension

 

Hypertension has been recently identified as an inflammatory disease. Immune cell infiltration is a characteristic feature in the vasculature and the kidneys in experimental hypertension, but the unique nature of such inflammatory infiltrates has not yet been comprehensively characterised.

Accordingly, we aimed to provide in-depth characteristics of immune cells in the vasculature and the kidneys in experimental hypertension.

To achieve this, we used single-cell RNA-sequencing of leukocytes (CD45+ cells were sorted) using the 10x Genomics platform in the aortas and the kidneys of male 12-week-old C57BL/6J mice (n=16–17/group) upon AngII (490 ng/min/kg) or sham buffer 14-day infusion, using osmotic minipumps. Samples were pooled to analyse three independent replicates. Bioinformatics analysis used Seurat/R to identify immune cell subpopulations and characterise differentially expressed genes (DEGs), pathways, and interactions signatures.

Ang II infusion increases the total number of CD45+ leukocytes in the aorta (346.7±89.1 vs. 1210±214.3; p=0,048), while in the kidneys, this was much less pronounced (1.1±0.5 fold vs. sham). Fifteen leukocyte populations/clusters were identified in the aorta and kidney based on their unique markers. In the aorta, shifts in numerous populations were evident, with the most significant differences in tissue-resident macrophages and activated tissue-resident macrophages, monocyte-derived dendritic cells and NK cells (Figure 1). Kidneys did not display such profound changes. The transcriptomic profile analysis showed 767 significant DEGs in the aorta and only 35 in the kidney. CellChat analysis also indicated more robust interactions between the immune cells in the aorta than in kidneys. These included Ifitm1, Apoe, Il1b, and C1q a/b/c, which were shared between aorta and kidney and may play an immunoregulatory role, affecting smooth muscle cell proliferation and arterial vascular remodelling. Top up-regulated leukocyte genes in the aorta included Ccl8, Ccl3, Cxcl2, Lyz2, and Spp1, while in the kidney, Cd74, Cst3, Fos, Fcer1g, Tyrobp, and Ccl4. GO pathway signatures of aortic leukocyte DEGs revealed pathways related to leukocyte migration, cytokine production, T cell activation, and leukocyte activation and adhesion. Cell-specific analysis showed that macrophage subpopulations most strongly increased in Ang II-induced hypertension displayed the most pronounced changes in the transcriptome profiles and cell-cell interactions.

Comprehensive single-cell RNA sequencing identifies tissue-resident macrophages, monocyte-derived dendritic cells, and NK cells as most affected leukocyte subpopulations in hypertensive vasculature. Differentially expressed genes support the role of these cells in vascular remodelling and propagation of inflammation, further supporting the identification of these cells as potential future targets for therapeutic interventions in hypertension.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Research Council

Protection against angiotensin II-induced hypertension in mice lacking sphingosine kinase 1 in vascular smooth muscle cells

Background

Sphingosine-1-phosphate (S1P), a lipid mediator produced by sphingosine kinases (Sphks), significantly contributes to the maintenance of cardiovascular homeostasis. Mice lacking Sphk1 globally are protected against angiotensin II-induced hypertension, yet, due to pleiotropic action of S1P, it has been challenging to identify a specific cell type responsible for this protection.

Purpose

The aim of this study was to investigate the role of Sphk1 expressed in vascular smooth muscle cells (VSMCs) in the development of angiotensin II (AngII)-induced hypertension in mice.

Methods

Male, 12-week-old C57BL/6J wild type (WT) or VSMC-specific, Cre-mediated, Sphk1 knockout (Sphk1VSMC−/−) mice underwent either Sham or AngII (490 ng/min/kg s.c.) treatment for 2 weeks, using a surgically implanted osmotic minipump. Blood pressure was measured by the tail-cuff method. Vascular structure and function were examined ex vivo using wire (vasoconstrictor/vasorelaxant responses) and pressure myography (myogenic tone, structural and elasticity parameters). Gene set enrichment analysis (GSEA) was performed using transcriptomic profiles of the isolated mesenteric arteries (MA, RNASeq). Expression of proteins was analyzed by Western blot.

Results

Deletion of Sphk1 in VSMCs resulted in 5x and 40x lower expression of Sphk1 mRNA in MA and aorta compared to WT mice respectively. A 2-week infusion of AngII resulted in a development of higher systolic blood pressure (SBP) in WT mice compared to Sphk1VSMC−/− mice (mean SBP ± SEM: 168±4.3 mmHg vs. 132±4.4 mmHg respectively, p<0.05). Studies of ex vivo mesenteric artery (MA) function revealed diminished both, depolarization-induced (in response to KCl), as well as G protein-coupled receptor-elicited (in response to phenylephrine and thromboxane A2 analogue) contraction of MA derived from hypertensive Sphk1VSMC−/− mice compared to WT mice. In the same time, significantly impaired endothelial vasorelaxation was observed in MA of hypertensive Sphk1VSMC−/− compared to hypertensive WT mice. Moreover, MA from Sphk1VSMC−/− mice were characterized by the significantly reduced myogenic response evoked by intravascular pressure elevation (maximal myogenic response ± SEM: 19.7±1.8% for WT normotensive, 26.2±1.8% for WT AngII vs. 19.0±2.5% for Sphk1VSMC−/− AngII mice), and an increased stiffness compared to WT mice. GSEA found that the lack of Sphk1 gene in VSMCs significantly downregulated molecular pathways related to smooth muscle contraction. In line with transcriptomic studies, significantly reduced level of the Rho-associated protein kinase (Rock) has been observed in MA of hypertensive Sphk1VSMC−/− compared to hypertensive WT mice using Western blot.

Conclusions

This study revealed that mice lacking Sphk1 gene in VSMCs are protected against the development of AngII-induced hypertension likely due to the lowered myogenic tone in resistance arteries, which may be mediated by autocrine effects of Sphk1 on Rock proteins.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The National Science Centre, Poland

Breast cancer chemotherapy induces vascular dysfunction and hypertension through NOX4 dependent mechanism

Cardiovascular disease is the major cause of morbidity and mortality in breast cancer survivors. Chemotherapy contributes to this risk. We aimed to define the mechanisms of long-term vascular dysfunction caused by neoadjuvant chemotherapy (NACT) and identify novel therapeutic targets.We studied arteries from postmenopausal women who had undergone breast cancer treatment using docetaxel, doxorubicin and cyclophosphamide (NACT), and women with no history of such treatment matched for key clinical parameters. Mechanisms were explored in wild-type and Nox4-/- mice and human microvascular endothelial cells.Endothelium-dependent vasodilatation is severely impaired in patients after NACT, while endothelium-independent responses remain normal. This was mimicked by 24-hour exposure of arteries to NACT agents ex-vivo. When applied individually, only docetaxel impaired endothelial function in human vessels. Mechanistic studies showed that NACT increased inhibitory eNOS phosphorylation of threonine 495 in a ROCK-dependent manner and augmented vascular superoxide and hydrogen peroxide production and NADPH oxidase activity. Docetaxel increased expression of NADPH oxidase NOX4 in endothelial and smooth muscle cells and NOX2 in the endothelium. NOX4 increase in human arteries may be mediated epigenetically by diminished DNA methylation of the NOX4 promoter. Docetaxel induced endothelial dysfunction and hypertension in mice. These were prevented in Nox4-/- and by pharmacological inhibition of Nox4 or Rock.Commonly used chemotherapeutic agents, and in particular, docetaxel, alter vascular function by promoting inhibitory phosphorylation of eNOS and enhancing ROS production by NADPH oxidases.

Neuroimmune cardiovascular interfaces control atherosclerosis

Atherosclerotic plaques develop in the inner intimal layer of arteries and can cause heart attacks and strokes¹. As plaques lack innervation, the effects of neuronal control on atherosclerosis remain unclear. However, the immune system responds to plaques by forming leukocyte infiltrates in the outer connective tissue coat of arteries (the adventitia)^2-6. Here, because the peripheral nervous system uses the adventitia as its principal conduit to reach distant targets^7-9, we postulated that the peripheral nervous system may directly interact with diseased arteries. Unexpectedly, widespread neuroimmune cardiovascular interfaces (NICIs) arose in mouse and human atherosclerosis-diseased adventitia segments showed expanded axon networks, including growth cones at axon endings near immune cells and media smooth muscle cells. Mouse NICIs established a structural artery-brain circuit (ABC): abdominal adventitia nociceptive afferents^10-14 entered the central nervous system through spinal cord T₆-T₁₃ dorsal root ganglia and were traced to higher brain regions, including the parabrachial and central amygdala neurons; and sympathetic efferent neurons projected from medullary and hypothalamic neurons to the adventitia through spinal intermediolateral neurons and both coeliac and sympathetic chain ganglia. Moreover, ABC peripheral nervous system components were activated: splenic sympathetic and coeliac vagus nerve activities increased in parallel to disease progression, whereas coeliac ganglionectomy led to the disintegration of adventitial NICIs, reduced disease progression and enhanced plaque stability. Thus, the peripheral nervous system uses NICIs to assemble a structural ABC, and therapeutic intervention in the ABC attenuates atherosclerosis.

Therapeutic targeting of inflammation in hypertension: from novel mechanisms to translational perspective

Both animal models and human observational and genetic studies have shown that immune and inflammatory mechanisms play a key role in hypertension and its complications. We review the effects of immunomodulatory interventions on blood pressure, target organ damage, and cardiovascular risk in humans. In experimental and small clinical studies, both non-specific immunomodulatory approaches, such as mycophenolate mofetil and methotrexate, and medications targeting T and B lymphocytes, such as tacrolimus, cyclosporine, everolimus, and rituximab, lower blood pressure and reduce organ damage. Mechanistically targeted immune interventions include isolevuglandin scavengers to prevent neo-antigen formation, co-stimulation blockade (abatacept, belatacept), and anti-cytokine therapies (e.g. secukinumab, tocilizumab, canakinumab, TNF-α inhibitors). In many studies, trial designs have been complicated by a lack of blood pressure-related endpoints, inclusion of largely normotensive study populations, polypharmacy, and established comorbidities. Among a wide range of interventions reviewed, TNF-α inhibitors have provided the most robust evidence of blood pressure lowering. Treatment of periodontitis also appears to deliver non-pharmacological anti-hypertensive effects. Evidence of immunomodulatory drugs influencing hypertension-mediated organ damage are also discussed. The reviewed animal models, observational studies, and trial data in humans, support the therapeutic potential of immune-targeted therapies in blood pressure lowering and in hypertension-mediated organ damage. Targeted studies are now needed to address their effects on blood pressure in hypertensive individuals.

Systemic and vascular inflammation in experimental allergic asthma

Allergic asthma and atherosclerosis are inflammatory diseases characterized by similar sets of circulating inflammatory cells, in addition to mast cells in the airway and vessel wall. Animal models and human studies provide evidence of a potential interaction between the two apparently unrelated diseases. The main objective of this study was to determine whether experimental allergic asthma is accompanied by inflammatory responses, measured as the activation of the vasculature and the presence of immune cells in the perivascular adipose tissue. For this purpose, male Dunkin Hartley guinea pigs weighing 250 - 300 g were sensitized twice with 10 μg ovalbumin dissolved in aluminium hydroxide (Al(OH)₃). Allergen inhalation was performed 10 days after the second immunization and continued 5 days a week for 2 months. After that period, T cell and macrophage content was measured by flow cytometry. The aortic expression of inflammatory markers was studied by real-time PCR. The number of T cells in the peripheral blood was significantly greater in the allergic group in comparison to the sham group. We did not find any significant differences in the leukocyte content of the perivascular adipose tissue between the groups. Nor did we identify significant changes in the expression of inflammatory markers (tumor necrosis factor, monocyte chemoattractant protein-1) and adhesion molecules (intercellular adhesion molecules and vascular cell adhesion molecules) in the aorta. Interestingly, we observed a significantly decreased expression of the endothelial nitric oxide synthase (eNOS) mRNA in the aortic vessel of the allergic group compared to the sham group.

COVID-19 and the cardiovascular system: implications for risk assessment, diagnosis, and treatment options

The novel coronavirus disease (COVID-19) outbreak, caused by SARS-CoV-2, represents the greatest medical challenge in decades. We provide a comprehensive review of the clinical course of COVID-19, its comorbidities, and mechanistic considerations for future therapies. While COVID-19 primarily affects the lungs, causing interstitial pneumonitis and severe acute respiratory distress syndrome (ARDS), it also affects multiple organs, particularly the cardiovascular system. Risk of severe infection and mortality increase with advancing age and male sex. Mortality is increased by comorbidities: cardiovascular disease, hypertension, diabetes, chronic pulmonary disease, and cancer. The most common complications include arrhythmia (atrial fibrillation, ventricular tachyarrhythmia, and ventricular fibrillation), cardiac injury [elevated highly sensitive troponin I (hs-cTnI) and creatine kinase (CK) levels], fulminant myocarditis, heart failure, pulmonary embolism, and disseminated intravascular coagulation (DIC). Mechanistically, SARS-CoV-2, following proteolytic cleavage of its S protein by a serine protease, binds to the transmembrane angiotensin-converting enzyme 2 (ACE2) -a homologue of ACE-to enter type 2 pneumocytes, macrophages, perivascular pericytes, and cardiomyocytes. This may lead to myocardial dysfunction and damage, endothelial dysfunction, microvascular dysfunction, plaque instability, and myocardial infarction (MI). While ACE2 is essential for viral invasion, there is no evidence that ACE inhibitors or angiotensin receptor blockers (ARBs) worsen prognosis. Hence, patients should not discontinue their use. Moreover, renin-angiotensin-aldosterone system (RAAS) inhibitors might be beneficial in COVID-19. Initial immune and inflammatory responses induce a severe cytokine storm [interleukin (IL)-6, IL-7, IL-22, IL-17, etc.] during the rapid progression phase of COVID-19. Early evaluation and continued monitoring of cardiac damage (cTnI and NT-proBNP) and coagulation (D-dimer) after hospitalization may identify patients with cardiac injury and predict COVID-19 complications. Preventive measures (social distancing and social isolation) also increase cardiovascular risk. Cardiovascular considerations of therapies currently used, including remdesivir, chloroquine, hydroxychloroquine, tocilizumab, ribavirin, interferons, and lopinavir/ritonavir, as well as experimental therapies, such as human recombinant ACE2 (rhACE2), are discussed.

Chanzyme TRPM7 protects against cardiovascular inflammation and fibrosis

AIMS

Transient Receptor Potential Melastatin 7 (TRPM7) cation channel is a chanzyme (channel + kinase) that influences cellular Mg2+ homeostasis and vascular signalling. However, the pathophysiological significance of TRPM7 in the cardiovascular system is unclear. The aim of this study was to investigate the role of this chanzyme in the cardiovascular system focusing on inflammation and fibrosis.

METHODS AND RESULTS

TRPM7-deficient mice with deletion of the kinase domain (TRPM7+/Δkinase) were studied and molecular mechanisms investigated in TRPM7+/Δkinase bone marrow-derived macrophages (BMDM) and co-culture systems with cardiac fibroblasts. TRPM7-deficient mice had significant cardiac hypertrophy, fibrosis, and inflammation. Cardiac collagen and fibronectin content, expression of pro-inflammatory mediators (SMAD3, TGFβ) and cytokines [interleukin (IL)-6, IL-10, IL-12, tumour necrosis factor-α] and phosphorylation of the pro-inflammatory signalling molecule Stat1, were increased in TRPM7+/Δkinase mice. These processes were associated with infiltration of inflammatory cells (F4/80+CD206+ cardiac macrophages) and increased galectin-3 expression. Cardiac [Mg2+]i, but not [Ca2+]i, was reduced in TRPM7+/Δkinase mice. Calpain, a downstream TRPM7 target, was upregulated (increased expression and activation) in TRPM7+/Δkinase hearts. Vascular functional and inflammatory responses, assessed in vivo by intra-vital microscopy, demonstrated impaired neutrophil rolling, increased neutrophil: endothelial attachment and transmigration of leucocytes in TRPM7+/Δkinase mice. TRPM7+/Δkinase BMDMs had increased levels of galectin-3, IL-10, and IL-6. In co-culture systems, TRPM7+/Δkinase macrophages increased expression of fibronectin, proliferating cell nuclear antigen, and TGFβ in cardiac fibroblasts from wild-type mice, effects ameliorated by MgCl2 treatment.

CONCLUSIONS

We identify a novel anti-inflammatory and anti-fibrotic role for TRPM7 and suggest that its protective effects are mediated, in part, through Mg2+-sensitive processes.

T-Cell-Derived miRNA-214 Mediates Perivascular Fibrosis in Hypertension

RATIONALE

Despite increasing understanding of the prognostic importance of vascular stiffening linked to perivascular fibrosis in hypertension, the molecular and cellular regulation of this process is poorly understood.

OBJECTIVES

To study the functional role of microRNA-214 (miR-214) in the induction of perivascular fibrosis and endothelial dysfunction driving vascular stiffening.

METHODS AND RESULTS

Out of 381 miRs screened in the perivascular tissues in response to Ang II (angiotensin II)-mediated hypertension, miR-214 showed the highest induction (8-fold, P=0.0001). MiR-214 induction was pronounced in perivascular and circulating T cells, but not in perivascular adipose tissue adipocytes. Global deletion of miR-214^-/- prevented Ang II-induced periaortic fibrosis, Col1a1, Col3a1, Col5a1, and Tgfb1 expression, hydroxyproline accumulation, and vascular stiffening, without difference in blood pressure. Mechanistic studies revealed that miR-214^-/- mice were protected against endothelial dysfunction, oxidative stress, and increased Nox2, all of which were induced by Ang II in WT mice. Ang II-induced recruitment of T cells into perivascular adipose tissue was abolished in miR-214^-/- mice. Adoptive transfer of miR-214^-/- T cells into RAG1^-/- mice resulted in reduced perivascular fibrosis compared with the effect of WT T cells. Ang II induced hypertension caused significant change in the expression of 1380 T cell genes in WT, but only 51 in miR-214^-/-. T cell activation, proliferation and chemotaxis pathways were differentially affected. MiR-214^-/- prevented Ang II-induction of profibrotic T cell cytokines (IL-17, TNF-α, IL-9, and IFN-γ) and chemokine receptors (CCR1, CCR2, CCR4, CCR5, CCR6, and CXCR3). This manifested in reduced in vitro and in vivo T cell chemotaxis resulting in attenuation of profibrotic perivascular inflammation. Translationally, we show that miR-214 is increased in plasma of patients with hypertension and is directly correlated to pulse wave velocity as a measure of vascular stiffness.

CONCLUSIONS

T-cell-derived miR-214 controls pathological perivascular fibrosis in hypertension mediated by T cell recruitment and local profibrotic cytokine release.

Cardiovascular Effects of Pharmacological Targeting of Sphingosine Kinase 1

High blood pressure is a risk factor for cardiovascular diseases. Ang II (angiotensin II), a key pro-hypertensive hormone, mediates target organ consequences such as endothelial dysfunction and cardiac hypertrophy. S1P (sphingosine-1-phosphate), produced by Sphk1 (sphingosine kinase 1), plays a pivotal role in the pathogenesis of hypertension and downstream organ damage, as it controls vascular tone and regulates cardiac remodeling. Accordingly, we aimed to examine if pharmacological inhibition of Sphk1 using selective inhibitor PF543 can represent a useful vasoprotective and cardioprotective anti-hypertensive strategy in vivo. PF543 was administered intraperitoneally throughout a 14-day Ang II-infusion in C57BL6/J male mice. Pharmacological inhibition of Sphk1 improved endothelial function of arteries of hypertensive mice that could be mediated via decrease in eNOS (endothelial nitric oxide synthase) phosphorylation at T495. This effect was independent of blood pressure. Importantly, PF543 also reduced cardiac hypertrophy (heart to body weight ratio, 5.6±0.2 versus 6.4±0.1 versus 5.9±0.2 mg/g; P<0.05 for Sham, Ang II+placebo, and Ang II+PF543-treated mice, respectively). Mass spectrometry revealed that PF543 elevated cardiac sphingosine, that is, Sphk1 substrate, content in vivo. Mechanistically, RNA-Seq indicated a decreased expression of cardiac genes involved in actin/integrin organization, S1pr1 signaling, and tissue remodeling. Indeed, downregulation of Rock1 (Rho-associated coiled-coil containing protein kinase 1), Stat3 (signal transducer and activator of transcription 3), PKC (protein kinase C), and ERK1/2 (extracellular signal-regulated kinases 1/2) level/phosphorylation by PF543 was observed. In summary, pharmacological inhibition of Sphk1 partially protects against Ang II-induced cardiac hypertrophy and endothelial dysfunction. Therefore, it may represent a promising target for harnessing residual cardiovascular risk in hypertension.

P2256Aging and inhibition of Nox4 and Nox1 exacerbate perivascular inflammation in spontaneous hypertension

Introduction

Hypertension is associated with enhanced NADPH oxidase activation and increased accumulation of immune cells leading to perivascular inflammation. However, while aging and oxidative stress are a major factor for the development of hypertension, their effect on perivascular inflammation remains unclear.

Purpose

We aimed to establish the interaction between aging, oxidative stress and perivascular inflammation.

We hypothesize that the modulation of oxidative stress, by NADPH oxidase inhibition, could affect perivascular inflammation during the aging.

Methods

Using flow cytometry, we studied leukocyte infiltration in the perivascular adipose tissue (PVAT) in 1-, 3-, 6- and 12-month-old SHR (Spontaneously Hypertensive Rats) and normotensive WKY (Wistar-Kyoto) rats (n=5–12). Additionally, 1-month-old rats were treated with GKT137831 or ML171 (60mg/kg; NOX1/4 and NOX1 inhibitor, respectively) for 4 weeks. Blood pressure (PB) was measured by tail cuff. Statistical analysis was performed using two-way ANOVA or t-test. Data are presented as means±SEM.

Results

Aging in SHRs was associated with an increase of BP (139±4 vs. 180±4 vs. 203±3 vs. 209±3, mmHg) and an elevation of PVAT leukocytes (2090±164 vs. 2255±359 vs. 2502±496 vs. 3255±408, cell/mg) in 1-, 3-, 6- and 12-month-old rats, respectively. These effects were not seen in WKY.

These were associate with similar changes of NK cells (p int <0.001) and macrophages (p int <0.001) in the SHR PVAT. Within T cell compartment, TH17 cells in PVAT were only elevated with age in SHR (1.04±0.08% vs. 1.89±0.2%, 1.08±0.1% vs. 2.03±0.2%, 1.71% vs. 4.37±0.5%, WKY vs. SHR, 3-,6- and 12-months, respectively, p int<0.001).

While an age-related increase of Nox4 mRNA in the vessels was observed in both groups, this increase was more dynamic in SHRs, (p int <0.05). Furthermore, 5-, 6- and 9-fold induction of Nox1 mRNA was observed in the vessels of 3-, 6- and 12-months-old SHRs, respectively (p<0.01).

Interestingly, GKT137831 increased BP in both WKY and SHR rats (p<0.01, 2-way ANOVA). This was accompanied by the elevation of leukocytes (988±180 vs 147±188 cell/mg, 1487±945 vs 1878±164 cell/mg) and macrophages (107±14 vs. 153±14 cell/mg, 228±26 vs. 298±42 cell/mg) in PVAT of both WKYs and SHRs treated with GKT137831. Moreover, GKT137831 treatment significantly increased (p int<0.01) percentage of TH17 in PVAT of both normotensive (1.4±0.2% vs. 2.5±0.2%) and hypertensive (2.3±0.1% vs. 2.9±0.1%) animals. On the contrary, ML171 treatment, inhibiting only Nox1, in turn protected against an increase of PVAT leukocytes especially among macrophages, TH17 cells (p<0.01).

Conclusion

Aging and spontaneous hypertension is associated with a trajectory of BP elevation and perivascular inflammation. This state is hastened after NOX1/4 inhibition, while ML171 treatment protects against perivascular inflammation.

Acknowledgement/Funding

National Science Centre 2013/11/N/NZ4/00310

Effects of controlled physical activity on immune cell phenotype in peripheral blood in prehypertension - studies in preclinical model and randomised crossover study

Hypertension (HT) is a global public health issue. There are many behavioural risk factors including unhealthy diet, tobacco use and alcohol consumption as well physical inactivity that contribute to the development of high blood pressure (BP) and its complications. Favourable effect of regular physical activity on treatment or prevention of hypertension by improvement of endothelial function is widely accepted however little is known about its relationship with immune system. Thus, the aim of this study was to assess the role of moderate regular physical activity on immune cell phenotype. T cell and monocyte subsets were characterised in 31 subjects with prehypertension (130 - 139 mmHg systolic and 85 - 89 mmHg diastolic blood pressure) who participated in moderate training (3 times/week) on cyclometers for 3 months in crossover study design. Complementary study was performed in murine model of Ang II-induced hypertension and ten-week-old animals were trained on a treadmill (5 times/week, 1 hour) for 2 weeks before and 1.5 weeks after minipumps implantation. In the context of elevated blood pressure regular physical activity had modest influence on immune cell phenotype. Both in human study and murine model we did not observe effects of applied exercise that can explain the mechanism of BP reduction after short-term regular training. Twelve-weeks regular training did not affect the activation status of T lymphocytes measured as expression of CD69, CD25 and CCR5 in human study. Physical activity resulted in higher expression of adhesion molecule CD11c on CD16+ monocytes (especially CD14 high) without any changes in leukocytes subpopulation counts. Similar results were observed in murine model of hypertension after the training. However the training caused significant decrease of CCR5 and CD25 expressions (measured as a mean fluorescence intensity) on CD8+ T cells infiltrating perivascular adipose tissue. Our studies show modest regulatory influence of moderate training on inflammatory markers in prehypertensive subjects and murine model of Ang II induced hypertension.

1,2,3,4,6-Penta-O-galloyl-β-d-glucose modulates perivascular inflammation and prevents vascular dysfunction in angiotensin II-induced hypertension

Background and Purpose

Hypertension is a multifactorial disease, manifested by vascular dysfunction, increased superoxide production, and perivascular inflammation. In this study, we have hypothesized that 1,2,3,4,6‐penta‐O‐galloyl‐β‐d‐glucose (PGG) would inhibit vascular inflammation and protect from vascular dysfunction in an experimental model of hypertension.

Experimental Approach

PGG was administered to mice every 2 days at a dose of 10 mg·kg⁻¹ i.p during 14 days of Ang II infusion. It was used at a final concentration of 20 μM for in vitro studies in cultured cells.

Key Results

Ang II administration increased leukocyte and T‐cell content in perivascular adipose tissue (pVAT), and administration of PGG significantly decreased total leukocyte and T‐cell infiltration in pVAT. This effect was observed in relation to all T‐cell subsets. PGG also decreased the content of T‐cells bearing CD25, CCR5, and CD44 receptors and the expression of both monocyte chemoattractant protein 1 (CCL2) in aorta and RANTES (CCL5) in pVAT. PGG administration decreased the content of TNF⁺ and IFN‐γ⁺ CD8 T‐cells and IL‐17A⁺ CD4⁺ and CD3⁺CD4⁻CD8⁻ cells. Importantly, these effects of PGG were associated with improved vascular function and decreased ROS production in the aortas of Ang II‐infused animals independently of the BP increase. Mechanistically, PGG (20 μM) directly inhibited CD25 and CCR5 expression in cultured T‐cells. It also decreased the content of IFN‐γ⁺ CD8⁺ and CD3⁺CD4⁻CD8⁻ cells and IL‐17A⁺ CD3⁺CD4⁻CD8⁻ cells.

Conclusion and Implication

PGG may constitute an interesting immunomodulating strategy in the regulation of vascular dysfunction and hypertension.

Linked Articles

This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc

Th1-type immune responses to Porphyromonas gingivalis antigens exacerbate angiotensin II-dependent hypertension and vascular dysfunction

Background and Purpose

Emerging evidence indicates that hypertension is mediated by immune mechanisms. We hypothesized that exposure to Porphyromonas gingivalis antigens, commonly encountered in periodontal disease, can enhance immune activation in hypertension and exacerbate the elevation in BP, vascular inflammation and vascular dysfunction.

Experimental Approach

Th1 immune responses were elicited through immunizations using P. gingivalis lysate antigens (10 μg) conjugated with aluminium oxide (50 μg) and IL‐12 (1 μg). The hypertension and vascular endothelial dysfunction evoked by subpressor doses of angiotensin II (0.25 mg·kg⁻¹·day⁻¹) were studied, and vascular inflammation was quantified by flow cytometry and real‐time PCR.

Key Results

Systemic T‐cell activation, a characteristic of hypertension, was exacerbated by P. gingivalis antigen stimulation. This translated into increased aortic vascular inflammation with enhanced leukocyte, in particular, T‐cell and macrophage infiltration. The expression of the Th1 cytokines, IFN‐γ and TNF‐α, and the transcription factor, TBX21, was increased in aortas of P. gingivalis/IL‐12/aluminium oxide‐immunized mice, while IL‐4 and TGF‐β were unchanged. These immune changes in mice with induced T‐helper‐type 1 immune responses were associated with an enhanced elevation of BP and endothelial dysfunction compared with control mice in response to 2 week infusion of a subpressor dose of angiotensin II.

Conclusions and Implications

These results support the concept that Th1 immune responses induced by bacterial antigens such as P. gingivalis can increase sensitivity to subpressor pro‐hypertensive insults such as low‐dose angiotensin II, thus providing a mechanistic link between chronic infection, such as periodontitis, and hypertension.

Linked Articles

This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc

Abstract P338: Aging and Inhibition of Nox1/4 Modulate Perivascular Inflammation in Spontaneous Hypertension

Introduction: Hypertension is associated with enhanced oxidative stress and perivascular inflammation. Although, that aging and oxidative stress are major factors in the development of hypertension their effect on perivascular inflammation remains unclear.

Methods: Using flow cytometry we studied leukocytes infiltrating perivascular adipose tissue (PVAT) in 1-, 3-, 6- and 12-month-old SHR (Spontaneously Hypertensive Rats) and normotensive WKY (Wistar-Kyoto) rats. Additionally, 1-month-old rats were treated with GKT137831 (60mg/kg) or ML171 (NOX1/4 and NOX1 inhibitor, respectively) for 4 weeks. Blood pressure (PB) was measured by the tail cuff.

Results: Aging in SHRs was associated with elevation of BP (139±4 vs 180±4 vs 202±2 vs 208±2 mmHg; 1 vs 3 vs 6 vs 12-month-old, respectively) when this effect was not seen in WKY rats. While the total number of leukocytes infiltrating PVAT were comparable between 1-month-old WKY and SHR (p=0.8) aging escalated their numbers only in SHRs (2096±164 vs 1994±296 vs 2311±470 vs 3255±408 cell/mg; p int <0.001). Similar effect was observed among NK cells (p int <0.001) and macrophages (p int <0.001). Moreover, spontaneous hypertension was associated with 2-fold elevation of T cells residing in PVAT in comparison to WKY, however, aging did not affect their number in both groups. While the age-related increase of Nox4 mRNA was observed in both groups, this increase was more dynamic in SHRs, (p int <0.05). Furthermore, 5-, 6- and 9-fold induction of Nox1 mRNA was observed in the vessels of 3-, 6- and 12-months-old SHRs, respectively (p<0.01). GKT137831 treatment significantly increased BP (p<0.01, 2way ANOVA) in both WKY and SHR (150±2 vs 164±3 mmHg, 198±4 vs 209±3 mmHg, respectively). This was accompanied by elevation of the total number of leukocytes (988±180 vs 1471±88 cell/mg, 1487±945 vs 1878±164 cell/mg) and macrophages (107±14 vs. 153±14 cell/mg, 228±26 vs. 298±42) in PVAT of WKYs and SHRs treated with GKT137831. On the contrary, ML171 treatment protected against increased accumulation of CD45+ cells in PVAT, without affecting BP.

Conclusions: Aging in spontaneous hypertension is associated with elevation of BP and aggravation of perivascular inflammation which are hastened after NOX1/4 inhibitor treatment.

Abstract 060: Role of Mir-214 in the Regulation of Perivascular Fibrosis in Angiotensin II Induced Hypertension

Objective: Hypertension (HT) is associated with perivascular inflammation and increased vascular fibrosis. MicroRNAs (miR) are a novel gene expression regulation mechanism and play a pivotal role in a range of pathological processes. The role and mechanism of miR214 in vascular fibrosis is unknown.

Methods: 3-month-old C57BL/6, miR214KO and wild-type littermates were treated with angiotensin II (AngII, 490ng/kg/min; n=6-10) or control buffer for 14 days. PVATs from C57BL/6 animals were analysed using TaqMan_Rodent_microRNA_Arrays. Histological studies, wire myography, lucigenin-enhanced luminometry and cytometrical analysis was conducted, followed by statistical analysis with ANOVA or t-test. Data are expressed as a mean±SEM.

Results: Out of 381 miRs, 16 were significantly overexpressed in C57BL/6 AngII animals, with only miR214 showing 8-fold induction (p<0.01) after Bonferroni correction. Also, 3-fold elevation of pri-miR-214 was observed. Interestingly, hydralazine treatment prevented both these changes (p<0.01). AngII infusion in miR214 KO animals did not alter blood pressure when compared to WT mice. Mir214 KOs exhibited diminished peri-aortic fibrosis (44779±2491 vs 78805±8696μm, p<0.01), upon AngII hypertension. This was associated with a significantly reduced induction of COL1A1, COL3A1 and TGFβ1 mRNA expression in PVAT and aortas (p<0.05). Vascular studies revealed improved endothelial function (69±10 vs. 22±4%, p<0.01), protection against oxidative stress (66±7 vs 118±19 RLU/sec/mg, p<0.001) and NOX2 mRNA expression (1.9±0.2 vs1.1±0.1, p<0.05) in AngII miR-214-KO aortas, while these parameters were not altered in mesenteric arteries. Recruitment of T cells into aortic PVAT was abolished in KO HT animals in comparison to control group (192±65 vs. 603±164 cell/mg; p<0.05). AngII HT was associated with 4-fold increase of miR-214 expression in the circulating peripheral blood T cells and 2-fold in the spleen. Moreover, AngII infusion increased TNFα mRNA expression in WT T cells (1±0.1 vs 1.6±0, p<0.01) whereas this effect was not seen in miR214 KO T cells (0.9±0.3 vs 0.9±0.1).

Conclusions: MiR-214 plays a major role in modulation of aortic fibrosis, vascular function, oxidative stress and perivascular inflammation.

Vascular transcriptome profiling identifies Sphingosine kinase 1 as a modulator of angiotensin II-induced vascular dysfunction

Vascular dysfunction is an important phenomenon in hypertension. We hypothesized that angiotensin II (AngII) affects transcriptome in the vasculature in a region-specific manner, which may help to identify genes related to vascular dysfunction in AngII-induced hypertension. Mesenteric artery and aortic transcriptome was profiled using Illumina WG-6v2.0 chip in control and AngII infused (490 ng/kg/min) hypertensive mice. Gene set enrichment and leading edge analyses identified Sphingosine kinase 1 (Sphk1) in the highest number of pathways affected by AngII. Sphk1 mRNA, protein and activity were up-regulated in the hypertensive vasculature. Chronic sphingosine-1-phosphate (S1P) infusion resulted in a development of significantly increased vasoconstriction and endothelial dysfunction. AngII-induced hypertension was blunted in Sphk1^-/- mice (systolic BP 167 ± 4.2 vs. 180 ± 3.3 mmHg, p < 0.05), which was associated with decreased aortic and mesenteric vasoconstriction in hypertensive Sphk1^-/- mice. Pharmacological inhibition of S1P synthesis reduced vasoconstriction of mesenteric arteries. While Sphk1 is important in mediating vasoconstriction in hypertension, Sphk1^-/- mice were characterized by enhanced endothelial dysfunction, suggesting a local protective role of Sphk1 in the endothelium. S1P serum level in humans was correlated with endothelial function (arterial tonometry). Thus, vascular transcriptome analysis shows that S1P pathway is critical in the regulation of vascular function in AngII-induced hypertension, although Sphk1 may have opposing roles in the regulation of vasoconstriction and endothelium-dependent vasorelaxation.

Novel Immune Mechanisms in Hypertension and Cardiovascular Risk

PURPOSE OF REVIEW

Hypertension is a common disorder with substantial impact on public health due to highly elevated cardiovascular risk. The mechanisms still remain unclear and treatments are not sufficient to reduce risk in majority of patients. Inflammatory mechanisms may provide an important mechanism linking hypertension and cardiovascular risk. We aim to review newly identified immune and inflammatory mechanisms of hypertension with focus on their potential therapeutic impact.

RECENT FINDINGS

In addition to the established role of the vasculature, kidneys and central nervous system in pathogenesis of hypertension, low-grade inflammation contributes to this disorder as indicated by experimental models and GWAS studies pointing to SH2B3 immune gene as top key driver of hypertension. Immune responses in hypertension are greatly driven by neoantigens generated by oxidative stress and modulated by chemokines such as RANTES, IP-10 and microRNAs including miR-21 and miR-155 with other molecules under investigation. Cells of both innate and adoptive immune system infiltrate vasculature and kidneys, affecting their function by releasing pro-inflammatory mediators and reactive oxygen species.

SUMMARY

Immune and inflammatory mechanisms of hypertension provide a link between high blood pressure and increased cardiovascular risk, and reduction of blood pressure without attention to these underlying mechanisms is not sufficient to reduce risk.

Perivascular adipose tissue inflammation in vascular disease

Perivascular adipose tissue (PVAT) plays a critical role in the pathogenesis of cardiovascular disease. In vascular pathologies, perivascular adipose tissue increases in volume and becomes dysfunctional, with altered cellular composition and molecular characteristics. PVAT dysfunction is characterized by its inflammatory character, oxidative stress, diminished production of vaso-protective adipocyte-derived relaxing factors and increased production of paracrine factors such as resistin, leptin, cytokines (IL-6 and TNF-α) and chemokines [RANTES (CCL5) and MCP-1 (CCL2)]. These adipocyte-derived factors initiate and orchestrate inflammatory cell infiltration including primarily T cells, macrophages, dendritic cells, B cells and NK cells. Protective factors such as adiponectin can reduce NADPH oxidase superoxide production and increase NO bioavailability in the vessel wall, while inflammation (e.g. IFN-γ or IL-17) induces vascular oxidases and eNOS dysfunction in the endothelium, vascular smooth muscle cells and adventitial fibroblasts. All of these events link the dysfunctional perivascular fat to vascular dysfunction. These mechanisms are important in the context of a number of cardiovascular disorders including atherosclerosis, hypertension, diabetes and obesity. Inflammatory changes in PVAT's molecular and cellular responses are uniquely different from classical visceral or subcutaneous adipose tissue or from adventitia, emphasizing the unique structural and functional features of this adipose tissue compartment. Therefore, it is essential to develop techniques for monitoring the characteristics of PVAT and assessing its inflammation. This will lead to a better understanding of the early stages of vascular pathologies and the development of new therapeutic strategies focusing on perivascular adipose tissue.

LINKED ARTICLES

This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.

Anti-atherosclerotic effect of the angiotensin 1-7 mimetic AVE0991 is mediated by inhibition of perivascular and plaque inflammation in early atherosclerosis

BACKGROUND AND PURPOSE

Inflammation plays a key role in atherosclerosis. The protective role of angiotensin 1-7 (Ang-(1-7)) in vascular pathologies suggested the therapeutic use of low MW, non-peptide Ang-(1-7) mimetics, such as AVE0991. The mechanisms underlying the vaso-protective effects of AVE0991, a Mas receptor agonist, remain to be explored.

EXPERIMENTAL APPROACH

We investigated the effects of AVE0991 on the spontaneous atherosclerosis in apolipoprotein E (ApoE)-/- mice, in the context of vascular inflammation and plaque stability.

KEY RESULTS

AVE0991 has significant anti-atherosclerotic properties in ApoE-/- mice and increases plaque stability, by reducing plaque macrophage content, without effects on collagen. Using the descending aorta of chow-fed ApoE-/- mice, before significant atherosclerotic plaque develops, we gained insight to early events in atherosclerosis. Interestingly, perivascular adipose tissue (PVAT) and adventitial infiltration with macrophages and T-cells precedes atherosclerotic plaque or the impairment of endothelium-dependent NO bioavailability (a measure of endothelial function). AVE0991 inhibited perivascular inflammation, by reducing chemokine expression in PVAT and through direct actions on monocytes/macrophages inhibiting their activation, characterized by production of IL-1β, TNF-α, CCL2 and CXCL10, and differentiation to M1 phenotype. Pretreatment with AVE0991 inhibited migration of THP-1 monocytes towards supernatants of activated adipocytes (SW872). Mas receptors were expressed in PVAT and in THP-1 cells in vitro, and the anti-inflammatory effects of AVE0991 were partly Mas dependent.

CONCLUSIONS AND IMPLICATIONS

The selective Mas receptor agonist AVE0991 exhibited anti-atherosclerotic and anti-inflammatory actions, affecting monocyte/macrophage differentiation and recruitment to the perivascular space during early stages of atherosclerosis in ApoE-/- mice.

LINKED ARTICLES

This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

Role of Tumor Necrosis Factor-α and Natural Killer Cells in Uterine Artery Function and Pregnancy Outcome in the Stroke-Prone Spontaneously Hypertensive Rat

Women with chronic hypertension are at increased risk of maternal and fetal morbidity and mortality. We have previously characterized the stroke-prone spontaneously hypertensive rat (SHRSP) as a model of deficient uterine artery function and adverse pregnancy outcome compared with the control Wistar-Kyoto. The activation of the immune system plays a role in hypertension and adverse pregnancy outcome. Therefore, we investigated the role of tumor necrosis factor-α in the SHRSP phenotype in an intervention study using etanercept (0.8 mg/kg SC) at gestational days 0, 6, 12, and 18 in pregnant SHRSP compared with vehicle-treated controls (n=6). Etanercept treatment significantly lowered systolic blood pressure after gestational day 12 and increased litter size in SHRSP. At gestational day 18, etanercept improved the function of uterine arteries from pregnant SHRSP normalizing the contractile response and increasing endothelium-dependent relaxation, resulting in increased pregnancy-dependent diastolic blood flow in the uterine arteries. We identified that the source of excess tumor necrosis factor-α in the SHRSP was a pregnancy-dependent increase in peripheral and placental CD3^- CD161⁺ natural killer cells. Etanercept treatment also had effects on placental CD161⁺ cells by reducing the expression of CD161 receptor, which was associated with a decrease in cytotoxic granzyme B expression. Etanercept treatment improves maternal blood pressure, pregnancy outcome, and uterine artery function in SHRSP by antagonizing signaling from excess tumor necrosis factor-α production and the reduction of granzyme B expression in CD161⁺ natural killer cells in SHRSP.

Abstract P228: Protective Role of TRPM7-kinase Against Vascular Dysfunction and Fibrosis Induced by Aldosterone and Salt

TRPM7 is a cationic ion channel and with a serine/threonine kinase important for cellular Mg 2+ homeostasis. We recently showed that TRPM7-kinase plays a role in aldosterone-mediated vascular effects and inflammation. Here we explored the role of TRPM7-kinase in cardiac fibrosis and vascular function in aldosterone-induced hypertension in mice. Wild-type (WT) or heterozygote TRPM7-kinase domain (TRPM7+/-) were treated with infused aldosterone (600 μg/Kg/day) and NaCl 1% in drinking water (aldo/salt) for 4 weeks. Blood pressure (BP) was evaluated by tail-cuff. Vessel function was investigated in mesenteric arteries by wire and pressure myography. Protein expression was assessed in cardiac tissue by western-blot and histology. Aldo/salt increased BP in TRPM7+/- and WT to similar levels (137mmHg vs control 118mmHg). Mesenteric arteries from untreated TRPM7+/- mice were more sensitive to relaxation induced by acetylcholine (LogEC50: 7.6±0.1 vs 7.1±0.2, TRPM7+/- and WT, respectively), effects that were reduced by Aldo/salt treatment (LogEC50: 7.2±0.1). Phenylephrine-contraction and sodium nitroprusside-relaxation curves were similar among groups. Pressure myography showed that in WT, aldo/salt increase the diameter (26%) and cross-sectional area (40%), resulting in hypertrophic outward remodelling, whereas in TRPM7+/-, the treatment decreased the diameter (16%) and increase the wall/lumen ration (82%), resulting in eutrophic inward remodelling. Hearts from TRPM7+/- presented decreased expression of annexin-1, which is a target protein of TRPM7-kinase, that was further decreased by aldo-salt. Hearts from untreated TRPM7+/- mice had increased fibrotic markers: plasma galectin-3 (2.5ng/mL) vs WT (1.4ng/mL) and protein expression for fibronectin (2.4-fold) and TGFβ (2-fold), and the aging marker p-P66Sch (47%) which were similar to WT-aldo/salt. Aldo/salt induced higher collagen expression in TRPM7+/- than in WT animals (15%), as observed by picrosirius red staining. Our findings provide some insights into aldosterone signalling through TRPM7-kinase and suggest that this chanzyme may have protective actions, which when downregulated, promotes vascular remodelling and cardiac fibrosis in aldosterone-induced hypertension.

Abstract 007: TRPM7-kinase Modulates Renal and Splenic Macrophage and T-lymphocyte Infiltration in Aldosterone-salt-induced Hypertension

TRPM7 is a Mg2 + channel linked to a kinase domain important in cell proliferation and survival. We demonstrated that cells deficient in TRPM7-kinase domain are prone to aldosterone (aldo)-induced oxidative stress and inflammation. Here, we investigated whether TRPM7-kinase plays a role in inflammatory responses in aldo-induced hypertension. Wild-type (WT) or heterozygote TRPM7-kinase domain (TRPM7+/-) mice were infused with aldo (600μg/Kg/day - osmotic minipumps) and 1% NaCl in the drinking water (aldo-salt) for 4 weeks. Inflammatory responses were evaluated by examining T cells (CD4+ and CD8+) and macrophages (M1- and M2-phenotype) infiltration in kidneys and spleens, using flow cytometry. Gene and protein expression was assessed by real-time PCR and immunoblot respectively. ROS was evaluated by lucigenin chemiluminescence. Aldo-salt increased kidney mass and urinary levels of albumin, Ca 2+ , Mg 2+ and K + , similarly in WT and TRPM7+/- (p<0.05 vs controls). Kidneys from TRPM7+/- mice presented a higher total number of inflammatory infiltrated cells (0.87x10 6 vs WT 0.22x10 6 cells/g), TCD4+ cells (27% vs WT 19%), and macrophages (47% vs WT 31%) (p<0.05 vs controls). Kidneys from WT aldo-salt showed increased ROS production (1.7-fold) and Nox2 (2-fold) protein expression (p<0.05 vs control) and presented similar cell infiltration to TRPM7+/- mice. Kidneys from TRPM7+/- aldo-salt show increased M2-macrophages CD206+ (4.3% vs WT 2.3%) and mRNA expression for the anti-inflammatory cytokine IL-10 (55% vs WT), whereas decreased the expression of the pro-inflammatory TNFα (30% vs WT) and Nox2 protein (1.8-fold). Spleen mass was increased by 40% only in WT aldo-salt. Spleens from untreated TRPM7+/- showed increased infiltrated inflammatory cells (3.7x10 8 vs WT 2.0x10 8 cells/mg). Splenic macrophages were higher in untreated TRPM7+/- (8.8% vs WT 5.9%) and presented an increase in CD206 M2-marker (16% vs WT 7%), higher TCD4+ (68% vs WT 50%) and TCD8+ (26% vs WT 17%), values that were similar to WT aldo-salt. Our data provide insights into the importance of the TRPM7-kinase domain in the immune system activation, which when down regulated provokes an increase in inflammatory cell infiltration in kidneys and spleens in aldo-salt-induced hypertension.

Abstract 046: The Role of Tumor Necrosis Factor α and Natural Killer Cells in Uterine Artery Function During Pregnancy in the Stroke Prone Spontaneously Hypertensive Rat

Objective: We have previously characterised the stroke prone spontaneously hypertensive rat (SHRSP) as a model of deficient uterine artery remodelling and identified an increase in pro-inflammatory TNFα relative to the normotensive WKY strain during pregnancy.

Method: SHRSP were treated with etanercept (0.8 mg/kg) or vehicle at gestational day (GD) 0, 6, 12 and 18. Animals were sacrificed at GD18.

Results: Etanercept reduced systolic blood pressure in the SHRSP after GD12 (ΔSBP GD 10-21 SHRSP 12.0 ± 4.17 vs. ETN 25.8 ± 4.27 mmHg; p<0.05). Uterine arteries from GD18 showed that etanercept reduced uterine artery contraction (SHRSP 57.3 ± 8.75 vs. ETN 35.2 ± 2.19 kPa; p<0.01) and increased carbachol response (SHRSP 13.8 ± 3.8 vs. ETN 40.1 ± 3.25 %; p<0.05). Uteroplacental blood flow analysed using Doppler showed that etanercept reduced uterine artery resistance index in SHRSP (SHRSP 0.79 ± 0.02 vs. ETN 0.61 ± 0.02 UARI; p<0.01). Etanercept increased litter size (SHRSP 7.80 ± 0.44 vs. ETN 12.75 ± 0.94 fetuses), reduced resorption frequency (SHRSP 66.7% vs. ETN 25.0% dams with resorption) and decreased glycogen cell loss from the placenta in SHRSP. We sought to identify the source of excess TNFα in the SHRSP. Natural killer (NK) cells (CD3-CD161+) were increased in the SHRSP relative to the WKY in the maternal circulation (WKY 1.5 ± 0.4 vs. SHRSP 6.06 ± 0.28 %; p<0.01) and placenta (WKY 11.6 ± 2.39 vs. SHRSP 659.8 ± 201.2 cells/mg; p<0.01). These NK cells produced excess TNFα in the SHRSP maternal circulation (SHRSP 6.5 ± 0.4 vs. WKY 2.5 ± 0.4 %; p<0.05) and placenta (SHRSP 65.7 ± 4.2 vs. WKY 16.9 ± 1.7 %; p<0.01) relative to the WKY. In the SHRSP placenta, etanercept treatment reduced the number of cytotoxic NK cells (SHRSP 659.8 ± 201.2 vs. ETN 148.0 ± 12.62 cells/mg; p<0.01) by down-regulating CD161 expression associated with a decrease in granzyme B production (CD161+ 71.47 ± 2.1 vs. CD161 Low 14.32 ± 0.77 % granzyme B+; p<0.01).

Conclusions: Excess TNFα plays a causative role in adverse pregnancy outcome in the SHRSP. One source of this TNFα is an increase in NK cells during gestation in the SHRSP. Etanercept targets NK cells in the SHRSP placenta and down-regulates cytotoxic granzyme B production.

Systemic T Cells and Monocyte Characteristics in Patients with Denture Stomatitis

PURPOSE

Chronic inflammatory disorders of the oral cavity, such as periodontitis, were recently linked to systemic immune activation. Since fungal oral infections have not yet been studied in this respect, the aim of our study is to determine whether the local inflammation caused by oral fungal infection of the palatal tissue (denture stomatitis-DS) is associated with the systemic inflammatory response. This question is becoming essential as the population ages.

MATERIALS AND METHODS

Peripheral blood of DS patients (n = 20) and control patients (n = 24) was assessed with flow cytometry to determine lymphocyte and monocyte profiles. Intracellular cytometric analysis was carried out to establish cytokine production by T cells. DS was diagnosed based on clinical symptoms of DS such as swelling and redness of oral mucosa, confirmed by microbiological swabs for fungal colonization with Candida species. The control group was recruited from denture users without clinical and microbiological signs of oral infections.

RESULTS

Percentages of peripheral lymphocytes, T cells, monocytes, and their subpopulations were similar in both studied groups. The exception was median percentages of CD25+ T cell subsets, which were significantly lower in DS patients than in control subjects. This reduction was observed in both CD4 T cell subset (16.7% and 28.1%; p = 0.0006) and CD8 T cell subset (4.6% and 7.0%; p = 0.007) CONCLUSIONS: While DS and associated local fungal infection do not overtly affect activation of monocytes or lymphocytes, the number of CD 25+ T cells is significantly lower in the DS patients, possibly indicating limited potential for the infection clearance in denture-using aging patients.

Role of chemokine RANTES in the regulation of perivascular inflammation, T-cell accumulation, and vascular dysfunction in hypertension

Recent studies have emphasized the role of perivascular inflammation in cardiovascular disease. We studied mechanisms of perivascular leukocyte infiltration in angiotensin II (Ang II)-induced hypertension and their links to vascular dysfunction. Chronic Ang II infusion in mice increased immune cell content of T cells (255 ± 130 to 1664 ± 349 cells/mg; P < 0.01), M1 and M2 macrophages, and dendritic cells in perivascular adipose tissue. In particular, the content of T lymphocytes bearing CC chemokine receptor (CCR) 1, CCR3, and CCR5 receptors for RANTES chemokine was increased by Ang II (CCR1, 15.6 ± 1.5% vs. 31 ± 5%; P < 0.01). Hypertension was associated with an increase in perivascular adipose tissue expression of the chemokine RANTES (relative quantification, 1.2 ± 0.2 vs. 3.5 ± 1.1; P < 0.05), which induced T-cell chemotaxis and vascular accumulation of T cells expressing the chemokine receptors CCR1, CCR3, and CCR5. Mechanistically, RANTES^−/− knockout protected against vascular leukocyte, and in particular T lymphocyte infiltration (26 ± 5% in wild type Ang II vs. 15 ± 4% in RANTES^−/−), which was associated with protection from endothelial dysfunction induced by Ang II. This effect was linked with diminished infiltration of IFN-γ-producing CD8⁺ and double-negative CD3⁺CD4⁻CD8⁻ T cells in perivascular space and reduced vascular oxidative stress while FoxP3⁺ T-regulatory cells were unaltered. IFN-γ ex vivo caused significant endothelial dysfunction, which was reduced by superoxide anion scavenging. In a human cohort, a significant inverse correlation was observed between circulating RANTES levels as a biomarker and vascular function measured as flow-mediated dilatation (R = −0.3, P < 0.01) or endothelial injury marker von Willebrand factor (R = +0.3; P < 0.01). Thus, chemokine RANTES is important in the regulation of vascular dysfunction through modulation of perivascular inflammation.—Mikolajczyk, T. P., Nosalski, R., Szczepaniak, P., Budzyn, K., Osmenda, G., Skiba, D., Sagan, A., Wu, J., Vinh, A., Marvar, P. J., Guzik, B., Podolec, J., Drummond, G., Lob, H. E., Harrison, D. G., Guzik, T. J. Role of chemokine RANTES in the regulation of perivascular inflammation, T-cell accumulation, and vascular dysfunction in hypertension.

Abstract 614: Anti-inflammatory Effect of Ang-(1-7) non-peptide mimetic (AVE 0991), on T Cell Infiltration in Perivascular Adipose Tissue in ApoE-/- Mice

Angiotensin 1-7 (Ang 1-7) has anti-atherosclerotic effects, possibly through its anti-inflammatory properties. As perivascular inflammation is an important component of early atherosclerosis, we aimed to determine whether angiotensin-(1-7) non peptide mimetic (AVE0991) can modulate these inflammatory mechanisms in the early development of atherosclerosis. Twelve-week old ApoE-/- mice and controls (C57BL/6J) on chow diet were treated with placebo or AVE0991 (0.58μM/g/day, per os). Mice were analysed at 16, 20 and 24 weeks of age. The level of perivascular leukocyte and T cell infiltration was measured by flow cytometry. Atherosclerotic plaque area was assessed by Oil Red O staining of en-face aortic preparations. Endothelial dysfunction was measured by wire myography and ROS production in the aorta by lucigenin-enhanced chemiluminescence (5μM). RESULTS: Levels of endogenous Ang 1-7, measured by mass spectrometry in the perivascular adipose tissue were low in both WT and ApoE-/- (32.9±1.2 vs 31.1±1.1 pg/mg; p=0.1). AVE0991 significantly reduced plaque area in ApoE-/- mice at all time points (14.2±1.9% vs 7.25±1.3% at 24 weeks; p<0.05). During this early stage of atherosclerosis there was no evidence of endothelial dysfunction and no significant increase in ROS generation in ApoE-/- mice. However, there was significant perivascular inflammation in 16 week old ApoE mice: CD45+ leukocytes were 2 fold higher in ApoE-/- mice vs controls (3200±850 vs 1700±267 cells/mg; p<0.05) and the number of CD3+ T in ApoE-/- mice was higher than in C57Bl/6J (638±88 vs 310±64 cells/mg; p<0.05). With aging, the number of leukocytes and T cells further increased in ApoE-/- but not in C57BL/6J mice, an effect abrogated by AVE0991. Moreover in cell culture of SW872 preadipocytes, AVE 0991 preincubation abolished TNF-α induced increase of chemokine RANTES and IL-6 mRNA expression. CONCLUSION: Ang-(1-7) non-peptide mimetic (AVE 0991) effectively inhibits early perivascular inflammation during the development of atherosclerotic plaque. This occurs independently of changes in redox status or endothelial dysfunction.

Vasodilatory effect and endothelial integrity in papaverine- and milrinone-treated human radial arteries

Prevention of the vasospasm is an important aspect of coronary artery bypass grafting (CABG) with the use of radial artery (RA) as the conduit. We compared the effect of two phosphodiesterase inhibitors papaverine and milrinone on vasodilation and endothelial integrity of human RA segments harvested from 20 CABG patients. Vasodilatory effect of the drugs were assessed by organ bath technique in RA rings precontracted with KCl and phenylephrine. Endothelial integrity was evaluated by CD34 immunofluorescence in frozen sections. Vasorelaxation induced by papaverine was significantly greater as compared to that induced by milrinone (90.47% ± 10.16% vs. 78.98% ± 19.56%, p<0.05). Similarly, pretreament with papaverine more strongly inhibited the contractile response of RA rings to KCl (6.0 ± 8.0 mN vs. 26.7 ± 21.5 mN, p<0.001). Papaverine was also superior to milrinone in the preservation of endothelial integrity (75.3% ± 12.9% vs. 51.8% ± 18.0%, p<0.02). In conclusion, papaverine seems to be more suitable than milrinone for prevention of vasospasm in radial artery conduits used for CABG.

Local inflammation is associated with aortic thrombus formation in abdominal aortic aneurysms. Relationship to clinical risk factors

Intraluminal thrombus formation in aortic abdominal aneurysms (AAA) is associated with adverse clinical prognosis. Interplay between coagulation and inflammation, characterised by leukocyte infiltration and cytokine production, has been implicated in AAA thrombus formation. We studied leukocyte (CD45+) content by flow cytometry in AAA thrombi from 27 patients undergoing surgical repair. Luminal parts of thrombi were leukocyte-rich, while abluminal segments showed low leukocyte content. CD66b+ granulocytes were the most prevalent, but their content was similar to blood. Monocytes (CD14+) and T cells (CD3+) were also abundant, while content of B lymphocytes (CD19+) and NK cells (CD56+CD16+) were low. Thrombi showed comparable content of CD14highCD16- monocytes and lower CD14highCD16+ and CD14dimCD16+, than blood. Monocytes were activated with high CD11b, CD11c and HLA-DR expression. Total T cell content was decreased in AAA thrombus compared to peripheral blood but CD8 and CD3+CD4-CD8- (double negative T cell) contents were increased in thrombi. CD4+ cells were lower but highly activated (high CD69, CD25 and HLA-DR). No differences in T regulatory (CD4+CD25+FoxP3+) cell or pro-atherogenic CD4+CD28null lymphocyte content were observed between thrombi and blood. Thrombus T cells expressed high levels of CCR5 receptor for chemokine RANTES, commonly released from activated platelets. Leukocyte or T cell content in thrombi was not correlated with aneurysm size. However, CD3+ content was significantly associated with smoking in multivariate analysis taking into account major risk factors for atherosclerosis. In conclusion, intraluminal AAA thrombi are highly inflamed, predominantly with granulocytes, CD14highCD16- monocytes and activated T lymphocytes. Smoking is associated with T cell infiltration in AAA intraluminal thrombi.

[Endothelial dysfunction related to oxidative stress and inflammation in perivascular adipose tissue]

Endothelial dysfunction plays an important role in the pathogenesis of many common diseases, like atherosclerosis and hypertension. The key role of the interaction between oxidative stress and inflammation in causal mechanisms of these diseases is widely accepted. Until recently, perivascular adipose tissue was not taken into account while looking at mechanisms of these disorders. However, it has recently been demonstrated that most processes involved in endothelial dysfunction development are taking place in this tissue. Adipocytes are an important source of free radicals and pro-inflammatory cytokines. These molecules lead to further enhancement of oxidative stress, through uncoupling of endothelial nitric oxide synthase (eNOS) and production of peroxynitrite radical instead of nitric oxide which further disrupts eNOS function. In addition, macrophages and T lymphocytes infiltrate adipose tissue as a result of chemotactic proteins release, upon oxidative stress activation, which further enhances inflammation. Thus, the chronic inflammation, which develops in this compartment of adipose tissue in patients with obesity, is the first step in the development of atherosclerotic plaque or hypertension. That is why comprehensive understanding of ongoing processes within perivascular adipocytes is so important.