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. A protective role of angiotensin-(1-7) in vascular pathologies opened a possibility for therapeutic use of small molecule non-peptide Ang-(1-7) mimetics, such as AVE0991. The mechanisms of these vaso-protective effects of a Mas receptor agonist, AVE0991, remain unclear. Experimental approach: We investigated the effects of AVE0991 on the spontaneous atherosclerosis in 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 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 as a measure of endothelial function. AVE0991 inhibited perivascular inflammation, through the reduction of chemokine expression in pVAT, as well as through direct actions on monocytes/macrophages inhibiting their activation, characterized by IL-1β, TNF-α, MCP-1 and CXCL10 and differentiation to M1 phenotype. Pre-treatment 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 anti-inflammatory effects of AVE0991 were partially Mas dependent. Conclusions & implications: Selective Mas receptor agonist AVE0991 possesses anti-atherosclerotic and anti-inflammatory properties, affecting monocyte/macrophage differentiation and recruitment to perivascular space at early stages of atherosclerosis in ApoE-/- mice

Nox1/4 inhibition exacerbates age dependent perivascular inflammation and fibrosis in a model of spontaneous hypertension

Hypertension is associated with oxidative stress and perivascular inflammation, critical contributors to perivascular fibrosis and accelerated vascular ageing. Oxidative stress can promote vascular inflammation, creating options for potential use of NADPH oxidase inhibitors in pharmacological targeting of perivascular inflammation and its consequences. Accordingly, we characterized age-related changes in oxidative stress and immune cell infiltration in normotensive (WKY) and spontaneously hypertensive rats (SHRs). Subsequently, we used pharmacological inhibitors of Nox1 (ML171) and Nox1/Nox4 (GKT137831; 60 mg/kg), to modulate NADPH oxidase activity at the early stage of spontaneous hypertension and investigated their effects on perivascular inflammation and fibrosis. Results: Ageing was associated with a progressive increase of blood pressure as well as an elevation of the total number of leukocytes, macrophages and NK cells infiltrating perivascular adipose tissue (PVAT) in SHRs but not in WKY. At 1 month of age, when blood pressure was not yet different, only perivascular NK cells were significantly higher in SHR. Spontaneous hypertension was also accompanied by the higher perivascular T cell accumulation, although this increase was age independent. Aortic Nox1 and Nox2 mRNA expression increased with age only in SHR but not in WKY, while age-related increase of Nox4 mRNA in the vessels has been observed in both groups, it was more pronounced in SHRs. At early stage of hypertension (3-months) the most pronounced differences were observed in Nox1 and Nox4. Surprisingly, GKT137831, dual inhibitor of Nox1/4, therapy increased both blood pressure and perivascular macrophage infiltration. Mechanistically, this was linked to increased expression of proinflammatory chemokines expression (CCL2 and CCL5) in PVAT. This inflammatory response translated to increased perivascular fibrosis. This effect was likely Nox4 dependent as the Nox1 inhibitor ML171 did not affect the development of spontaneous hypertension, perivascular macrophage accumulation, chemokine expression nor adventitial collagen deposition. In summary, spontaneous hypertension promotes ageing-associated perivascular inflammation which is exacerbated by Nox4 but not Nox1 pharmacological inhibition

Editorial: The interplay between oxidative stress, immune cells and inflammation in cardiovascular diseases

Cardiovascular diseases (CVDs) constitute the leading causes of death and reduced quality of life worldwide. Reactive oxygen species (ROS), various immune cells and cytokines participate in crucial signalling pathways implicated in the homeostasis of the cardiovascular system. Dysregulated ROS production and immune system activation have been widely demonstrated to lead to the development of CVDs, hypertension, target organ damage and cardiovascular complications (1, 2). Hypertension is a major risk factor leading to the development of cardiovascular diseases and target organ damage, including hypertensive heart disease. This pathology leads to abnormalities of the heart, involving changes in the structure and function of the left ventricle, the left atrium and coronary arteries. Masenga and Kirabo nicely summarised the current knowledge about hypertensive heart disease, highlighting this cardiac pathology's mechanisms, complications, and implications. In their comprehensive review, published in the current issue, they focused specifically on left ventricular hypertrophy, atrial fibrillation, heart failure, and coronary heart disease, and current and future therapies targeting these complications

Nox1/4 inhibition exacerbates age dependent perivascular inflammation and fibrosis in a model of spontaneous hypertension

Hypertension is associated with oxidative stress and perivascular inflammation, critical contributors to perivascular fibrosis and accelerated vascular ageing. Oxidative stress can promote vascular inflammation, creating options for potential use of NADPH oxidase inhibitors in pharmacological targeting of perivascular inflammation and its consequences. Accordingly, we characterized age-related changes in oxidative stress and immune cell infiltration in normotensive (WKY) and spontaneously hypertensive rats (SHRs). Subsequently, we used pharmacological inhibitors of Nox1 (ML171) and Nox1/Nox4 (GKT137831; 60 mg/kg), to modulate NADPH oxidase activity at the early stage of spontaneous hypertension and investigated their effects on perivascular inflammation and fibrosis. Results: Ageing was associated with a progressive increase of blood pressure as well as an elevation of the total number of leukocytes, macrophages and NK cells infiltrating perivascular adipose tissue (PVAT) in SHRs but not in WKY. At 1 month of age, when blood pressure was not yet different, only perivascular NK cells were significantly higher in SHR. Spontaneous hypertension was also accompanied by the higher perivascular T cell accumulation, although this increase was age independent. Aortic Nox1 and Nox2 mRNA expression increased with age only in SHR but not in WKY, while age-related increase of Nox4 mRNA in the vessels has been observed in both groups, it was more pronounced in SHRs. At early stage of hypertension (3-months) the most pronounced differences were observed in Nox1 and Nox4. Surprisingly, GKT137831, dual inhibitor of Nox1/4, therapy increased both blood pressure and perivascular macrophage infiltration. Mechanistically, this was linked to increased expression of proinflammatory chemokines expression (CCL2 and CCL5) in PVAT. This inflammatory response translated to increased perivascular fibrosis. This effect was likely Nox4 dependent as the Nox1 inhibitor ML171 did not affect the development of spontaneous hypertension, perivascular macrophage accumulation, chemokine expression nor adventitial collagen deposition. In summary, spontaneous hypertension promotes ageing-associated perivascular inflammation which is exacerbated by Nox4 but not Nox1 pharmacological inhibition

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 Tgfib1 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 nduced 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-a, IL-9, and IFN-y) 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

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

Abstract 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 &lt;0.001) and macrophages (p int &lt;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&lt;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 &lt;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&lt;0.01). Interestingly, GKT137831 increased BP in both WKY and SHR rats (p&lt;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&lt;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&lt;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 </jats:sec

Immune and inflammatory mechanisms in hypertension

Hypertension is a global health problem, with &gt;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