A critical function of Th17 proinflammatory cells in the development of atherosclerotic plaque in mice

Considerable evidence supports that the CD4(+) T cell-mediated immune response contributes to the development of atherosclerotic plaque. However, the effects of Th17 cells on atherosclerosis are not thoroughly understood. In this study, we evaluated the production and function of Th17 and Th1 cells in atherosclerotic-susceptible ApoE(-/-) mice. We observed that the proportion of Th17 cells, as well as Th1, increased in atherosclerotic ApoE(-/-) mice compared with nonatherosclerotic wild-type littermates. In ApoE(-/-) mice with atherosclerosis, the expression of IL-17 and retinoic acid-related orphan receptor γt was substantially higher in the arterial wall with plaque than in the arterial wall without plaque. Increased Th17 cells were associated with the magnitude of atherosclerotic plaque in ApoE(-/-) mice. Importantly, treatment of ApoE(-/-) mice with neutralizing anti-IL-17 Ab dramatically inhibited the development of atherosclerotic plaque, whereas rIL-17 application significantly promoted the formation of atherosclerotic plaque. These data demonstrate that Th17 cells play a critical role in atherosclerotic plaque formation in mice, which may have implications in patients with atherosclerosis.     

IL-17A is proatherogenic in high-fat diet-induced and Chlamydia pneumoniae infection-accelerated atherosclerosis in mice

The role of IL-17 in atherogenesis remains controversial. We previously reported that the TLR/MyD88 signaling pathway plays an important role in high-fat diet as well as Chlamydophila pneumoniae infection-mediated acceleration of atherosclerosis in apolipoprotein E-deficient mice. In this study, we investigated the role of the IL-17A in high-fat diet (HFD)- and C. pneumoniae-induced acceleration of atherosclerosis. The aortic sinus plaque and aortic lesion size and lipid composition as well as macrophage accumulation in the lesions were significantly diminished in IL-17A(-/-) mice fed an HFD compared with wild-type (WT) C57BL/6 control mice. As expected, C. pneumoniae infection led to a significant increase in size and lipid content of the atherosclerotic lesions in WT mice. However, IL-17A(-/-) mice developed significantly less acceleration of lesion size following C. pneumoniae infection compared with WT control despite similar levels of blood cholesterol levels. Furthermore, C. pneumoniae infection in WT but not in IL-17A(-/-) mice was associated with significant increases in serum concentrations of IL-12p40, CCL2, IFN-γ, and numbers of macrophages in their plaques. Additionally, in vitro studies suggest that IL-17A activates vascular endothelial cells, which secrete cytokines that in turn enhance foam cell formation in macrophages. Taken together, our data suggest that IL-17A is proatherogenic and that it plays an important role in both diet-induced atherosclerotic lesion development, and C. pneumoniae infection-mediated acceleration of atherosclerotic lesions in the presence of HFD.     

TCF7 is highly expressed in immune cells on the atherosclerotic plaques,and regulating inflammatory signaling via NFκB/AKT/STAT1 signaling

Atherosclerosis, which is the fundamental basis for cardiovascular diseases in the global world, is driven by multiple roles of the immune system in the circulation and vascular plaque. Recent studies demonstrated that T-cell infiltrates into aorta plaque and plays an important role in recruiting macrophages to the vascular wall. Here, using single-cell sequencing, we found T cells in patients’ plaques and differentially expressed genes (DEGs) of T cells in atherosclerosis mice. T cells and macrophages were continuously activated in atherosclerotic plaque in patients. Besides, other immune cells also take part in atherogenesis, such as natural killer (NK) cells, granulocytes. Interferon (IFN)/NFκB signaling, the AKT signaling pathway was highly activated in mouse (in vivo) and cell line (in vitro). TCF7 and XCL1 were regulated by AKT and NFκB, respectively through protein–protein network analysis. Therefore, we attempt to clarify and discover potential genes and new mechanisms associated with atherosclerosis for drug development.     

IL-22 produced by Th22 cells aggravates atherosclerosis development in ApoE−/− mice by enhancing DC-induced Th17 cell proliferation

Th22 cells are a novel subset of CD4⁺ T cells that primarily mediate biological effects through IL-22, with both Th22 cells and IL-22 being closely associated with multiple autoimmune and chronic inflammatory diseases. In this study, we investigated whether and how Th22 cells affect atherosclerosis. ApoE^−/− mice and age-matched C57BL/6J mice were fed a Western diet for 0, 4, 8 or 12 weeks. The results of dynamic analyses showed that Th22 cells, which secrete the majority of IL-22 among the known CD4⁺ cells, play a major role in atherosclerosis. ApoE^−/− mice fed a Western diet for 12 weeks and administered recombinant mouse IL-22 (rIL-22) developed substantially larger plaques in both the aorta and aortic root and higher levels of CD3⁺ T cells, CD68⁺ macrophages, collagen, IL-6, Th17 cells, dendritic cells (DCs) and pSTAT3 but lower smooth muscle cell (SMC) α-actin expression than the control mice. Treatment with a neutralizing anti–IL-22 monoclonal antibody (IL-22 mAb) reversed the above effects. Bone marrow-derived DCs exhibited increased differentiation into mature DCs following rIL-22 and ox-LDL stimulation. IL-17 and pSTAT3 were up-regulated after stimulation with IL-22 and ox-LDL in cells cocultured with CD4⁺ T cells and mature DC supernatant, but this up-regulation was significantly inhibited by IL-6mAb or the cell-permeable STAT3 inhibitor S31-201. Thus, Th22 cell-derived IL-22 aggravates atherosclerosis development through a mechanism that is associated with IL-6/STAT3 activation, DC-induced Th17 cell proliferation and IL-22–stimulated SMC dedifferentiation into a synthetic phenotype.     

Caveolin-1 influences vascular protease activity and is a potential stabilizing factor in human atherosclerotic disease

Caveolin-1 (Cav-1) is a regulatory protein of the arterial wall, but its role in human atherosclerosis remains unknown. We have studied the relationships between Cav-1 abundance, atherosclerotic plaque characteristics and clinical manisfestations of atherosclerotic disease.We determined Cav-1 expression by western blotting in atherosclerotic plaques harvested from 378 subjects that underwent carotid endarterectomy. Cav-1 levels were significantly lower in carotid plaques than non-atherosclerotic vascular specimens. Low Cav-1 expression was associated with features of plaque instability such as large lipid core, thrombus formation, macrophage infiltration, high IL-6, IL-8 levels and elevated MMP-9 activity. Clinically, a down-regulation of Cav-1 was observed in plaques obtained from men, patients with a history of myocardial infarction and restenotic lesions. Cav-1 levels above the median were associated with absence of new vascular events within 30 days after surgery [0% vs. 4%] and a trend towards lower incidence of new cardiovascular events during longer follow-up. Consistent with these clinical data, Cav-1 null mice revealed elevated intimal hyperplasia response following arterial injury that was significantly attenuated after MMP inhibition. Recombinant peptides mimicking Cav-1 scaffolding domain (Cavtratin) reduced gelatinase activity in cultured porcine arteries and impaired MMP-9 activity and COX-2 in LPS-challenged macrophages. Administration of Cavtratin strongly impaired flow-induced expansive remodeling in mice. This is the first study that identifies Cav-1 as a novel potential stabilizing factor in human atherosclerosis. Our findings support the hypothesis that local down-regulation of Cav-1 in atherosclerotic lesions contributes to plaque formation and/or instability accelerating the occurrence of adverse clinical outcomes. Therefore, given the large number of patients studied, we believe that Cav-1 may be considered as a novel target in the prevention of human atherosclerotic disease and the loss of Cav-1 may be a novel biomarker of vulnerable plaque with prognostic value.     

Atheroprotective Effect of Oleoylethanolamide (OEA) Targeting Oxidized LDL

Dietary fat-derived lipid oleoylethanolamide (OEA) has shown to modulate lipid metabolism through a peroxisome proliferator-activated receptor-alpha (PPAR-α)-mediated mechanism. In our study, we further demonstrated that OEA, as an atheroprotective agent, modulated the atherosclerotic plaques development. In vitro studies showed that OEA antagonized oxidized LDL (ox-LDL)-induced vascular endothelial cell proliferation and vascular smooth muscle cell migration, and suppressed lipopolysaccharide (LPS)-induced LDL modification and inflammation. In vivo studies, atherosclerosis animals were established using balloon-aortic denudation (BAD) rats and ApoE^-/- mice fed with high-caloric diet (HCD) for 17 or 14 weeks respectively, and atherosclerotic plaques were evaluated by oil red staining. The administration of OEA (5 mg/kg/day, intraperitoneal injection, i.p.) prevented or attenuated the formation of atherosclerotic plaques in HCD-BAD rats or HCD-ApoE^−/− mice. Gene expression analysis of vessel tissues from these animals showed that OEA induced the mRNA expressions of PPAR-α and downregulated the expression of M-CFS, an atherosclerotic marker, and genes involved in oxidation and inflammation, including iNOS, COX-2, TNF-α and IL-6. Collectively, our results suggested that OEA exerted a pharmacological effect on modulating atherosclerotic plaque formation through the inhibition of LDL modification in vascular system and therefore be a potential candidate for anti-atherosclerosis drug.     

IL-7R blockade reduces post-myocardial infarction-induced atherosclerotic plaque inflammation in ApoE−/- mice

Modulating inflammation by targeting IL-1β reduces recurrent athero-thrombotic cardiovascular events without lipid lowering. This presents an opportunity to explore other pathways associated with the IL-1β signaling cascade to modulate the inflammatory response post-myocardial infarction (MI). IL-7 is a mediator of the inflammatory pathway involved in monocyte trafficking into atherosclerotic plaques and levels of IL-7 have been shown to be elevated in patients with acute MI. Recurrent athero-thrombotic events are believed to be mediated in part by index MI-induced exacerbation of inflammation in atherosclerotic plaques. The objective of the study was to assess the feasibility of IL-7R blockade to modulate atherosclerotic plaque inflammation following acute MI in ApoE^?/- mice. Mice were fed Western diet for 12 weeks and then subjected to coronary occlusion to induce an acute MI. IL-7 expression was determined using qRT-PCR and immuno-staining, and IL-7R was assessed using flow cytometry. Plaque inflammation was evaluated using immunohistochemistry. IL-7R blockade was accomplished with monoclonal antibody to IL-7R. IL-7 mRNA expression was significantly increased in the cardiac tissue of mice subjected to MI but not in controls. IL-7 staining was observed in the coronary artery. Plaque macrophage and lipid content were significantly increased after MI. IL-7R antibody treatment but not control IgG significantly reduced macrophage and lipid content in atherosclerotic plaques. The results show that IL-7R antibody treatment reduces monocyte/macrophage and lipid content in the atherosclerotic plaque following MI suggesting a potential new target to mitigate increased plaque inflammation post-MI.     

Resveratrol protects against atherosclerosis,but does not add to the antiatherogenic effect of atorvastatin,in APOE*3-Leiden.CETP mice

Resveratrol is a major constituent of traditional Asian medicinal herbs and red wine and is suggested to be a potential antiatherosclerotic drug due to its proposed hypolipidemic, anti-inflammatory and antioxidative properties. The aim of this study was to evaluate whether resveratrol protects against atherosclerosis development in APOE*3-Leiden.CETP (E3L.CETP) mice and adds to the antiatherogenic effect of mild statin treatment, currently the most widely used antiatherogenic therapy. E3L.CETP mice were fed a cholesterol-rich diet without (control) or with resveratrol (0.01% w/w), atorvastatin (0.0027% w/w) or both for 14 weeks. During the study plasma lipid, inflammatory and oxidative stress parameters were determined. Resveratrol reduced atherosclerotic lesion area (?52%) in the aortic root, comparable to atorvastatin (?40%) and the combination of both drugs (?47%). The collagen/macrophage ratio in the atherosclerotic lesion, a marker of plaque stability, was increased by resveratrol (+108%), atorvastatin (+124%) and the combination (+154%). Resveratrol decreased plasma cholesterol levels (?19%) comparable to atorvastatin (?19%) and the combination (?22%), which was completely confined to (very)low-density lipoprotein cholesterol levels in all groups. Post hoc analyses showed that the antiatherogenic effect of atorvastatin could be explained by cholesterol lowering, while the antiatherosclerotic effect of resveratrol could be attributed to factors additional to cholesterol lowering. Markers of inflammation and oxidative stress were not different, but resveratrol improved macrophage function. We conclude that resveratrol potently reduces atherosclerosis development and induces a more stable lesion phenotype in E3L.CETP mice. However, under the experimental conditions tested, resveratrol does not add to the antiatherogenic effect of atorvastatin.     

Complement factor C5a induces atherosclerotic plaque disruptions

Complement factor C5a and its receptor C5aR are expressed in vulnerable atherosclerotic plaques; however, a causal relation between C5a and plaque rupture has not been established yet. Accelerated atherosclerosis was induced by placing vein grafts in male apoE^?/? mice. After 24 days, when advanced plaques had developed, C5a or PBS was applied locally at the lesion site in a pluronic gel. Three days later mice were killed to examine the acute effect of C5a on late stage atherosclerosis. A significant increase in C5aR in the plaque was detectable in mice treated with C5a. Lesion size and plaque morphology did not differ between treatment groups, but interestingly, local treatment with C5a resulted in a striking increase in the amount of plaque disruptions with concomitant intraplaque haemorrhage. To identify the potential underlying mechanisms, smooth muscle cells and endothelial cells were treated in vitro with C5a. Both cell types revealed a marked increase in apoptosis after stimulation with C5a, which may contribute to lesion instability in vivo. Indeed, apoptosis within the plaque was seen to be significantly increased after C5a treatment. We here demonstrate a causal role for C5a in atherosclerotic plaque disruptions, probably by inducing apoptosis. Therefore, intervention in complement factor C5a signalling may be a promising target in the prevention of acute atherosclerotic complications.     

Protein deglycase DJ-1 deficiency induces phenotypic switching in vascular smooth muscle cells and exacerbates atherosclerotic plaque instability

Protein deglycase DJ-1 (DJ-1) is a multifunctional protein involved in various biological processes. However, it is unclear whether DJ-1 influences atherosclerosis development and plaque stability. Accordingly, we evaluated the influence of DJ-1 deletion on the progression of atherosclerosis and elucidate the underlying mechanisms. We examine the expression of DJ-1 in atherosclerotic plaques of human and mouse models which showed that DJ-1 expression was significantly decreased in human plaques compared with that in healthy vessels. Consistent with this, the DJ-1 levels were persistently reduced in atherosclerotic lesions of ApoE^−/− mice with the increasing time fed by western diet. Furthermore, exposure of vascular smooth muscle cells (VSMCs) to oxidized low-density lipoprotein down-regulated DJ-1 in vitro. The canonical markers of plaque stability and VSMC phenotypes were evaluated in vivo and in vitro. DJ-1 deficiency in Apoe^−/− mice promoted the progression of atherosclerosis and exaggerated plaque instability. Moreover, isolated VSMCs from Apoe^−/−DJ-1^−/− mice showed lower expression of contractile markers (α-smooth muscle actin and calponin) and higher expression of synthetic indicators (osteopontin, vimentin and tropoelastin) and Kruppel-like factor 4 (KLF4) by comparison with Apoe^−/−DJ-1^+/+ mice. Furthermore, genetic inhibition of KLF4 counteracted the adverse effects of DJ-1 deletion. Therefore, our results showed that DJ-1 deletion caused phenotype switching of VSMCs and exacerbated atherosclerotic plaque instability in a KLF4-dependent manner.     

Perforin and Granzyme B Have Separate and Distinct Roles during Atherosclerotic Plaque Development in Apolipoprotein E Knockout Mice

The granzyme B/perforincytotoxic pathway is a well established mechanism of initiating target cell apoptosis. Previous studies have suggested a role for the granzyme B/perforin cytotoxic pathway in vulnerable atherosclerotic plaque formation. In the present study, granzyme B deficiency resulted in reduced atherosclerotic plaque development in the descending aortas of apolipoprotein E knockout mice fed a high fat diet for 30 weeks while perforindeficiency resulted in greater reduction in plaque development with significantly less plaque area than granzyme Bdeficient mice. In contrast to the descending aorta, no significant change in plaque size was observed in aortic roots from either granzyme Bdeficient or perforindeficient apolipoprotein E knockout mice. However, atherosclerotic plaques in the aortic roots did exhibit significantly more collagen in granzyme B, but not perforin deficient mice. Together these results suggest significant, yet separate roles for granzyme B and perforin in the pathogenesis of atherosclerosis that go beyond the traditional apoptotic pathway with additional implications in plaque development, stability and remodelling of extracellular matrix.     

Bisphosphonates induce inflammation and rupture of atherosclerotic plaques in apolipoprotein-E null mice

The apolipoprotein E knockout (Apo-E-/-) mouse is a well-known model of atherosclerosis. Bisphosphonates, through their affinity to hydroxyapatite, are known to reduce arterial calcification in several animal models. Thus, we examined the effect of two therapeutically used oral bisphosphonates, alendronate and risedronate, on plaque formation in the Apo-E-/- mouse. The drugs were administered by gavage to 16-week-old Apo-E-/- mice for 8 weeks. At 8 weeks, there was no difference in bone mineral density (BMD) of the alendronate- and risedronate-treated mice at any site. A time-dependent increase in BMD was demonstrated in Apo-E-/- mice with risedronate (p<0.01). Histological evaluation revealed that both bisphosphonates caused atherosclerotic plaque rupture. Five of 17 mice had severe inflammation with or without plaque rupture, while seven mice showed inflammation, but without plaque rupture. Neither caspase 3 nor metalloproteinases 2 and 9 were increased in ruptured plaques on immunocytochemistry. Quantitative measurements of arterial caliber remained unaffected. Our finding of plaque inflammation and rupture in bisphosphonate-treated Apo-E-/- mice may provide the first animal model for studies aimed at characterizing mechanisms of plaque rupture in animal models.     

MicroRNA-9 overexpression suppresses vulnerable atherosclerotic plaque and enhances vascular remodeling through negative regulation of the p38MAPK pathway via OLR1 in acute coronary syndrome

Acute coronary syndrome (ACS) is characterized by atherosclerotic plaque rupture with a high incidence of recurrent ischemic events. Several microRNAs are found to be aberrantly expressed in atherosclerotic plaques. This study aims to investigate the effects of microRNA-9 (miR-9) on vulnerable atherosclerotic plaque and vascular remodeling in ACS and underlying mechanisms. Microarray-based gene expression profiling was used to identify differentially expressed genes related to ACS and regulatory miRNAs. Oxidized low-density lipoprotein (lectin-like) receptor 1 (OLR1) was identified to be aberrantly activated in ACS and regulated by miR-9. OLR1 was verified as a target gene of miR-9 by bioinformatics prediction and dual luciferase reporter gene assay. The atherosclerotic models were induced in ApoE^−/− mice, in which the agomir or antagomir of miR-9, or small interfering RNA (siRNA) against OLR1 were separately introduced. Serum lipid levels and expression of vascular remodeling and inflammatory response-related factors were determined, respectively. On the basis of the obtained results, in the atherosclerosis mice treated with the agomir of miR-9 and siRNA against OLR1, the p38-mitogen-activated protein kinase (p38MAPK) pathway was inhibited; levels of triglyceride, total cholesterol, low-density lipoprotein cholesterol, tumor necrosis factor-α, interleukin-6, and vascular endothelial growth factor were reduced, but the high-density lipoprotein cholesterol level was increased, along with decreased vulnerable atherosclerotic plaque area and enhanced vascular remodeling. Taken together, these findings suggested an inhibitory role miR-9 acts in the formation of vulnerable atherosclerotic plaques in ACS mice, along with a promoted vascular remodeling, via a negative feedback regulation of OLR1-mediated p38MAPK pathway.     

Citreoviridin Enhances Atherogenesis in Hypercholesterolemic ApoE-Deficient Mice via Upregulating Inflammation and Endothelial Dysfunction

Vascular endothelial dysfunction and inflammatory response are early events during initiation and progression of atherosclerosis. In vitro studies have described that CIT markedly upregulates expressions of ICAM-1 and VCAM-1 of endothelial cells, which result from NF-κB activation induced by CIT. In order to determine whether it plays a role in atherogenesis in vivo, we conducted the study to investigate the effects of CIT on atherosclerotic plaque development and inflammatory response in apolipoprotein E deficient (apoE^-/-) mice. Five-week-old apoE^-/- mice were fed high-fat diets and treated with CIT for 15 weeks, followed by assay of atherosclerotic lesions. Nitric oxide (NO), vascular endothelial growth factor (VEGF) and endothelin-1 (ET-1) were detected in serum. Levels of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), VEGF, and ET-1 in plaque areas of artery walls were examined. NF-κB p65 expression and NF-κB activation in aorta also were assessed. CIT treatment significantly augmented atherosclerotic plaques and increased expressions of ICAM-1, VCAM-1, VEGF and ET-1 in aorta. Mechanistic studies showed that activation of NF-κB was significantly elevated by CIT treatment, indicating the effect of CIT on atherosclerosis may be regulated by activation of NF-κB.     

Recent insights into atherosclerotic plaque cell autophagy

Cardiovascular and cerebrovascular diseases, such as coronary heart disease and stroke, caused by atherosclerosis have become the “number one killer”, seriously endangering human health in developing and developed countries. Atherosclerosis mainly occurs in large and medium-sized arteries and involves intimal thickening, accumulation of foam cells, and formation of atheromatous plaques. Autophagy is a cellular catabolic process that has evolved to defend cells from the turnover of intracellular molecules. Autophagy is thought to play an important role in the development of plaques. This review focuses on studies on autophagy in cells involved in the formation of atherosclerotic plaques, such as monocytes, macrophages, endothelial cells, dendritic cells, and vascular smooth muscle cells, indicating that autophagy plays an important role in plaque development. We mainly discuss the roles of autophagy in these cells in maintaining the stability of atherosclerotic plaques, providing a reference for the next steps to unravel the mechanisms of atherogenesis.     

实验性动脉粥样斑块内泡沫细胞凋亡及葛根总黄酮的干预作用

目的:观察ApoE基因敲除(ApoE gene knock out,ApoE-/-)小鼠主动脉窦动脉粥样硬化斑块超微结构改变,泡沫细胞凋亡,探讨葛根总黄酮(Total Flavone of Radix Puerariae,TFRP)的干预作用。方法:将16只Apo E-/-小鼠随机分为模型组及TFRP干预组(85 mg/kg.d),每组8只,2只C57BL/6J小鼠作为空白对照,12周后处死,用酶法检测二组血清脂质含量,采用光学显微镜、电子显微镜观察As斑块形态及泡沫细胞凋亡。结果:(1)两组血清总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)及高密度脂蛋白胆固醇(HDL-C)水平未见显著性差异;(2)光镜观察:模型组可见成熟的As斑块形成,部分斑块脂质核心较大,偏心性,纤维帽较薄,纤维帽内有较多炎症细胞浸润,平滑肌细胞成分少,肩部较薄弱,呈不稳定斑块形成趋势,在斑块脂质核心内可见到较多凋亡细胞;而TFRP干预组未见不稳定斑块,斑块脂质核心小,平滑肌细胞数目较多,纤维帽较厚,斑块内凋亡细胞数明显少于模型组(p<0.05)。(3)电镜观察:模型组斑块内以平滑肌源性泡沫细胞多见,可见中晚期凋亡细胞,细胞外基质成分较少;与模型组相比,TFRP干预组以巨噬细胞源性泡沫细胞多见,可见少数早期凋亡细胞,细胞外胶原纤维明显增多。结论:模型组病变处于中晚期As病变,符合泡沫细胞凋亡特征;TFRP干预抑制了ApoE基因敲除小鼠主动脉窦As斑块内泡沫细胞凋亡。     

The Modulation of Endoplasmic Reticulum Stress by Chemical Chaperone Upregulates Immune Negative Cytokine IL-35 in Apolipoprotein E-Deficient Mice

Interleukin (IL)-35 is a newly identified immune negative molecule which is secreted by CD4⁺Foxp3⁺ T regulatory cells (Tregs) and contributes to their suppressive capacity. Early data have shown that IL-35 inhibits development of several autoimmune diseases. However, the role of IL-35 in atherosclerosis, a lipid-driven chronic inflammatory disease in arterial wall, remains to be investigated. Here, we found that IL-35 was involved in atherosclerosis in apolipoprotein E-deficient (ApoE^−/−) mice. ApoE^−/− mice with established atherosclerotic lesion displayed a lower level of IL-35 compared to age-matched wild type C57BL/6 mice without plaque. However, IL-35 expression increased significantly in ApoE^−/− mice with attenuated plaque. More importantly, we found that modulation of ER stress treated by chemical chaperone, 4-Phenyl butyric acid (PBA) in vivo, mainly upregulated immune negative regulating molecule IL-35, as well as IL-10 and Foxp3, accompanied by increased Tregs. However, no obvious impact on pro-inflammatory molecules such as TNF-α, IFN-γ, IL-17 and IL-23 was observed, which provides new insight into the benefit of ER stress recovery from attenuated plaque. Our results suggest that IL-35 might have a potential value for atherosclerotic therapy.     

Effects of emotional and physiological stress on plaque instability in apolipoprotein E knockout mice

In the present study, we sought to investigate the effects of emotional and physiological stress on plaque instability in atherosclerosis. We used different stress-treated apolipoprotein E (ApoE)-deficient mice, which have been shown to spontaneously develop atherosclerosis with features similar to those seen in humans, as an animal model. Morphology study showed that emotional stress (ES) obviously promoted the development of atherosclerotic plaques and plaque instability evidenced by significantly increasing plaque size, plaque-to-surface ratio and plaque calcification, and enhancing the frequency of large necrotic core and medial erosion compared with control ApoE^−/− mice (P < 0.01). Physiological stress (PS) treatment alone did not affect the plaque stability compared with control ApoE^−/− mice (P > 0.05). However, the combination of ES and PS treatment (CS) initiated much stronger plaque instability compared with ES treatment alone (P < 0.01), increased the frequency of thin fibrous caps, and even triggered plaque rupture and buried fibrous cap. Immunohistochemical analysis indicated that both ES and CS treatment led to an increase in the accumulation of macrophages and T cells and a decrease of smooth muscle cells, reflecting an unstable atherosclerotic plaque phenotype, in the atherosclerotic lesions in ApoE^−/− mice. PS alone did not affect plaque cellular components. Similarly, CS-mediated changes in atherosclerotic plaque composition were stronger than that caused by ES alone (P < 0.01). Taken together, ES treatment alone is sufficient to promote plaque instability. PS alone does not affect atherosclerotic plaque development, but can potentiate ES-mediated plaque destabilization.     

StemBell therapy stabilizes atherosclerotic plaques after myocardial infarction

Background aims. After a myocardial infarction (MI) atherosclerosis is accelerated leading to destabilization of the atherosclerotic plaque. mesenchymal stromal cells are a promising therapeutic option for atherosclerosis. Previously, we demonstrated a novel stem cell delivery technique, with adipose stem cells coupled to microbubbles (i.e., StemBells) as therapy after MI. In this study, we aim to investigate the effect of StemBell therapy on atherosclerotic plaques in an atherosclerotic mouse model after MI. Methods. MI was induced in atherosclerotic Apolipoprotein E–deficient mice that were fed a high-fat Western diet. Six days post-MI, the mice received either 5?×?10⁵/100 µL StemBells or vehicle intravenously. The effects of StemBell treatment on the size and stability of aortic root atherosclerotic plaques and the infarcted heart were determined 28 days post-MI via (immuno)histological analyses. Moreover, monocyte subtypes and lipids in the blood were studied. Results. StemBell treatment resulted in significantly increased cap thickness, decreased intra-plaque macrophage density and increased percentage of intra-plaque anti-inflammatory macrophages and chemokines, without affecting plaque size and serum cholesterol/triglycerides. Furthermore, StemBell treatment significantly increased the percentage of anti-inflammatory macrophages within the infarcted myocardium but did not affect cardiac function nor infarct size. Finally, also the average percentage of anti-inflammatory monocytes in the circulation was increased after StemBell therapy. Discussion. StemBell therapy increased cap thickness and decreased intra-plaque inflammation after MI, indicative of stabilized atherosclerotic plaque. It also induced a shift of circulating monocytes and intra-plaque and intra-cardiac macrophages towards anti-inflammatory phenotypes. Hence, StemBell therapy may be a therapeutic option to prevent atherosclerosis acceleration after MI.