Localizing factors in atherosclerosis

Association of sex and cardiovascular risk factors with atherosclerosis distribution pattern in lower extremity peripheral artery disease

Objective

Atherosclerosis expression varies across not only coronary, cerebrovascular, and peripheral arteries but also within the peripheral vascular tree. The underlying pathomechanisms of distinct atherosclerosis phenotypes in lower extremity peripheral artery disease (PAD) is poorly understood. We investigated the association of cardiovascular risk factors (CVRFs) and atherosclerosis distribution in a targeted approach analyzing symptomatic patients with isolated anatomic phenotypes of PAD.

Methods

In a cross-sectional analysis of consecutive patients undergoing first-time endovascular recanalization for symptomatic PAD, data of patients with isolated anatomic phenotypes of either proximal (iliac) or distal (infrageniculate) atherosclerosis segregation were extracted. We performed a multivariable logistic regression model with backward elimination to investigate the association of proximal and distal PAD with CVRFs.

Results

Of the 637 patients (29% females) with endovascular recanalization, 351 (55%) had proximal and 286 (45%) had distal atherosclerosis. Female sex [odds ratio (OR) 0.33, 95% confidence interval (CI) 0.20-0.54, p = 0.01], active smoking (OR 0.16, 95% CI 0.09-0.28, p < 0.001), and former smoking (OR 0.33, 95% CI 0.20-0.57, p < 0.001) were associated with proximal disease. Diabetes mellitus (DM) (OR 3.25, 95% CI 1.93-5.46, p < 0.001), chronic kidney disease (CKD) (OR 1.18, 95% CI 1.08-1.28, p < 0.001), and older age (OR 1.31, 95% CI 1.06-1.61, p = 0.01) were associated with distal disease.

Conclusion

Female sex, particularly in the context of smoking, is associated with clinically relevant, proximal atherosclerosis expression. Our additional findings that distal atherosclerosis expression is associated with DM, CKD, and older age suggest that PAD has at least two distinct atherosclerotic phenotypes with sex-specific and individual susceptibility to atherogenic risk factors.

Extent and progression of atherosclerosis in carotid and subclavian arteries: the Carotid Artery Subclavian Artery study

AIMS

To define the prevalence, progression, and the relationship between carotid and subclavian artery atherosclerosis and to identify factors associated with disease progression in a population of asymptomatic patients.

METHODS

Among all consecutive patients without a history of cardiovascular disease admitted to our hospital for duplex ultrasound examinations of the supra-aortic arteries, from January to December 2012, we retrospectively identified 530 patients with two evaluations at least 3 years apart. Each artery was graded according to stenosis degree, as absent or less than 20%, 20-49%, 50-69%, 70-99% and total occlusion. Disease progression was defined for any class increase at any time interval. Patients were grouped according to the presence of a more than 20% stenosis of the supra-aortic district at baseline, as controls, without atherosclerosis: n = 111, 21%; isolated carotid artery disease: n = 390, 74%; concomitant subclavian artery-carotid artery disease: n = 29, 5%. There were no cases with isolated subclavian artery atherosclerosis.

RESULTS

The mean time-lapse between the two evaluations was 3.1 ± 0.3 years; we documented disease progression in 32 patients (6%), all limited to the carotid artery (P = 0.009 vs. controls, with no differences between isolated carotid artery disease and concomitant carotid and subclavian artery disease). Hypertension was significantly (P < 0.001) associated with disease progression, regardless of the single or double district involvement.

CONCLUSION

The subclavian artery is far less prone to atherosclerosis than the carotid artery, and features lesser disease progression. Understanding factors for the different susceptibility to atherosclerosis in these two close arterial districts provides insight into local factors prompting vascular disease.

Impact of Lesion Preparation Technique on Side Branch Compromise in Calcified Coronary Bifurcations: A Subgroup Analysis of the PREPARE-CALC Trial

Objectives

To analyze the impact of different techniques of lesion preparation of severely calcified coronary bifurcation lesions.

Background

The impact of different techniques of lesion preparation of severely calcified coronary bifurcation lesions is poorly investigated.

Methods

We performed an as-treated analysis on 47 calcified bifurcation lesions treated with scoring/cutting balloons (SCB) and 68 lesions treated with rotational atherectomy (RA) in the PREPARE-CALC trial. Compromised side branch (SB) as assessed in the final angiogram was the primary outcome measure and was defined as any significant stenosis, dissection, or thrombolysis in myocardial infarction flow <3.

Results

True bifurcation lesions were present in 49% vs. 43% of cases in the SCB and RA groups, respectively. After stent implantation, SB balloon dilatation was necessary in around one-third of cases (36% vs. 38%; p = 0.82), and a two-stent technique was performed in 21.3% vs. 25% (p = 0.75). At the end of the procedure, the SB remained compromised in 15 lesions (32%) in the SCB group and 5 lesions (7%) in the RA group (p = 0.001). Large coronary dissections were more frequently observed in the SCB group (13% vs. 2%; p = 0.02). Postprocedural levels of cardiac biomarkers were significantly higher in patients with a compromised SB at the end of the procedure.

Conclusions

In the PREPARE-CALC trial, side branch compromise was more frequently observed after lesion preparation with SCB as compared with RA. Consequently, in calcified bifurcation lesions, an upfront debulking with an RA-based strategy might optimize the result in the side branch.

Mitochondrial Dysfunction and DNA Damage in the Context of Pathogenesis of Atherosclerosis

Atherosclerosis is a multifactorial disease of the cardiovascular system associated with aging, inflammation, and oxidative stress. An important role in the development of atherosclerosis play elevated plasma lipoproteins. A number of external factors (smoking, diabetes, infections) can also contribute to the development of the disease. For a long time, atherosclerosis remains asymptomatic, therefore, the search for early markers of the disease is critical for the timely management and better outcomes for patients. Mitochondrial dysfunction and mitochondrial DNA (mtDNA) damage appear to connect different aspects of atherosclerosis pathogenesis. To date, multiple lines of research have demonstrated the strong association of mitochondrial dysfunction with the development of various human diseases. Therapies aimed at restoring the mitochondrial function are being actively developed, and are expected to broaden the therapeutic possibilities for several chronic human diseases. The development of such therapies depends on our understanding of the functional roles of different mtDNA variants associated with one or another disorder, and the molecular mechanisms linking mitochondrial dysfunction with a given pathological feature. These questions are, however, challenging and require future intensive research. This review summarizes the recent studies and describes the central processes of the development of atherosclerosis, and shows their relationship with mitochondrial dysfunction. One of the promising therapeutic approaches for future atherosclerosis treatments is the use of mitochondria-targeted antioxidants. Future studies should focus on characterizing the mechanisms of mitochondrial involvement in cardiovascular pathologies to better direct the search for novel therapies.

Altered Tregs Differentiation and Impaired Autophagy Correlate to Atherosclerotic Disease

Atherosclerosis is a progressive vascular disease representing the primary cause of morbidity and mortality in developed countries. Formerly, atherosclerosis was considered as a mere passive accumulation of lipids in blood vessels. However, it is now clear that atherosclerosis is a complex and multifactorial disease, in which the involvement of immune cells and inflammation play a key role. A variety of studies have shown that autophagy-a cellular catalytic mechanism able to remove injured cytoplasmic components in response to cellular stress-may be proatherogenic. So far, in this context, its role has been investigated in smooth muscle cells, macrophages, and endothelial cells, while the function of this catabolic protective process in lymphocyte functionality has been overlooked. The few studies carried out so far, however, suggested that autophagy modulation in lymphocyte subsets may be functionally related to plaque formation and development. Therefore, in this research, we aimed at better clarifying the role of lymphocyte subsets, mainly regulatory T cells (Tregs), in human atherosclerotic plaques and in animal models of atherosclerosis investigating the contribution of autophagy on immune cell homeostasis. Here, we investigate basal autophagy in a mouse model of atherosclerosis, apolipoprotein E (ApoE)-knockout (KO) mice, and we analyze the role of autophagy in driving Tregs polarization. We observed defective maturation of Tregs from ApoE-KO mice in response to tumor growth factor-β (TGFβ). TGFβ is a well-known autophagy inducer, and Tregs maturation defects in ApoE-KO mice seem to be related to autophagy impairment. In this work, we propose that autophagy underlies Tregs maturation, advocating that the study of this process in atherosclerosis may open new therapeutic strategies.

Potential Therapeutic Anti-Inflammatory and Immunomodulatory Effects of Dihydroflavones, Flavones, and Flavonols

Systemic inflammation, circulating immune cell activation, and endothelial cell damage play a critical role in vascular pathogenesis. Flavonoids have shown anti-inflammatory effects. In this study, we investigated the effects of different flavonoids on the production of pro-inflammatory interleukin (IL) 1β, 6, and 8, and tumor necrosis factor α (TNF-α), in peripheral blood cells. Methods: We studied the whole blood from 36 healthy donors. Lipopolysaccharide (LPS)-stimulated (0.5 μg/mL) whole-blood aliquots were incubated in the presence or absence of different concentrations of quercetin, rutin, naringenin, naringin, diosmetin, and diosmin for 6 h. Cultures were centrifuged and the supernatant was collected in order to measure IL-1β, TNF-α, IL-6, and IL-8 production using specific immunoassay techniques. This production was significantly inhibited by quercetin, naringenin, naringin, and diosmetin, but in no case by rutin or diosmin. Flavonoids exert different effects, maybe due to the differences between aglycons and glucosides present in their chemical structures. However, these studies suggest that quercetin, naringenin, naringin, and diosmetin could have a potential therapeutic effect in the inflammatory process of cardiovascular disease.

Calcific lesion preparation for coronary bifurcation stenting

Bifurcating coronary lesions are a very common challenge in interventional cardiology because of the technical complexity in their treatment, the risk of side branch occlusion and an overall worse outcome when compared to non-bifurcating lesions. The presence of calcifications represents further complexity due to the difficulty in device delivery and stent expansion as well as enhanced risk of side branch occlusion. Rotational and orbital atherectomy, scoring and cutting balloons, coronary lithoplasty are available tools which have been introduced over the last three decades to overcome such issue. Nevertheless, their application in different contexts of bifurcations presents specific caveats and the studies directed at comparing such techniques have never been expressly oriented in the subset of the bifurcating lesion. In this paper, we review these devices and their usefulness in bifurcations by analyzing consistent data from clinical trials, and we propose a practical algorithm for the treatment of severely calcified bifurcating lesions according to their anatomical features.

Investigation of highly expressed PCSK9 in atherosclerotic plaques and ox-LDL-induced endothelial cell apoptosis

The present study aimed to explore the direct toxicity of proprotein convertase subtilisin/kexin type 9 (PCSK9) to atherosclerosis (AS) and its association with apoptotic endothelial cells. Apolipoprotein E−/− mice were randomly divided into two groups, control and experimental. The control group was administered a normal diet and the experimental group was administered a high-fat diet. After 20 weeks, the aorta was isolated and dissected. Hematoxylin and eosin staining, and immunohistochemical analysis were performed. Human umbilical vein endothelial cells were incubated with varied concentrations of oxidized low-density lipoprotein (ox-LDL) for different times. The apoptotic rate was detected by flow cytometry. Western blotting and reverse transcription-quantitative polymerase chain reaction analysis were conducted to detect the expression of PCSK9, B-cell lymphoma 2 (Bcl-2), bcl-2-like protein 4 (Bax) and caspase-3. Short hairpin (sh) RNA-PCSK9 was transfected into endothelial cells using lentiviral transfection. The expression levels of PCSK9, Bax, Bcl-2, caspase-3 and the mitogen-activated protein kinase (MAPK) pathway proteins were detected. The high-fat group was successfully established as an AS model and PCSK9 was highly expressed in the AS plaque. Treatment with ox-LDL induced apoptosis and increased mRNA and protein levels of PCSK9. PCSK9 mRNA and proteins levels were downregulated by shRNA-PCSK9. The deficiency of PCSK9 markedly inhibited the expression of pro-apoptotic proteins and promoted anti-apoptotic proteins. In addition, phosphorylation of p38 and c-Jun N-terminal kinases was altered by shRNA-PCSK9. Targeting of PCSK9 by shRNA-PCSK9 may repress endothelial cell apoptosis through MAPK signaling in AS, providing a novel direction for understanding the mechanism and treatment of AS.

Ghrelin inhibits atherosclerotic plaque angiogenesis and promotes plaque stability in a rabbit atherosclerotic model

Intraplaque angiogenesis associates with the instability of atherosclerotic plaques. In the present study, we investigated the effects of ghrelin on intraplaque angiogenesis and plaque instability in a rabbit model of atherosclerosis. The rabbits were randomly divided into three groups, namely, the control group, atherosclerotic model group, and ghrelin-treated group, with treatments lasting for 4 weeks. We found that the thickness ratio of the intima to media in rabbits of the ghrelin-treated group was significantly lower than that in rabbits of the atherosclerotic model group. The number of neovessels and the levels of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor 2 (VEGFR2) decreased dramatically in rabbits of the ghrelin-treated group compared to those of the atherosclerotic model group. Ghrelin significantly decreased the plaque content of macrophages, matrix metalloproteinase (MMP)-2, and MMP-9, in a rabbit model of atherosclerosis. In addition, the level of the pro-inflammatory factor monocyte chemoattractant protein (MCP)-1 was significantly lower in rabbits of the ghrelin-treated group than in rabbits of the atherosclerotic model group. In summary, ghrelin can inhibit intraplaque angiogenesis and promote plaque stability by down-regulating VEGF and VEGFR2 expression, inhibiting the plaque content of macrophages, and reducing MCP-1 expression at an advanced stage of atherosclerosis in rabbits.

Silencing of Transient Receptor Potential Channel 4 Alleviates oxLDL-induced Angiogenesis in Human Coronary Artery Endothelial Cells by Inhibition of VEGF and NF-κB

Background

Transient receptor potential channel 4 (TRPC4) plays central roles in endothelial cell function. The aim of this study was to investigate the silencing effects of TRPC4 on oxidized low-density lipoprotein (oxLDL)-induced angiogenesis in human coronary artery endothelial cells (HCAECs), as well as the underlying molecular mechanism involved in this process.

Material/Methods

HCAECs were transfected with small interfering RNA (siRNA) targeting TRPC4 (TRPC4-siRNA) or with a negative control (NC)-siRNA. The expression of TRPC4 was confirmed by real-time polymerase chain reaction (RT-PCR) and Western blotting. After the siRNA transfection, oxLDL was added to the medium. Cell proliferation, migration, and in vitro angiogenesis were determined by bromodeoxyuridine (BrdU) enzyme-linked immunosorbent assay (ELISA), Transwell assay and scratch-wound assay, respectively, and tube formation on Matrigel. Expression of vascular endothelial growth factor (VEGF) and nuclear factor (NF)-κB p65 were assessed by Western blotting.

Results

Both the mRNA and protein levels of TRPC4 were significantly reduced by transfection with TRPC4-siRNA compared to the control group or NC-siRNA group (P<0.05). Silencing of TRPC4 significantly decreased the cell proliferation, migration, and tube formation (all P<0.05). Furthermore, the expression levels of VEGF and NF-κB p65 were markedly lowered by silencing of TRPC4 in HCAECs.

Conclusions

These results suggest that silencing of TRPC4 alleviates angiogenesis induced by oxLDL in HCAECs through inactivation of VEGF and NF-κB. Suppression of TRPC4 might be an alternative therapeutic strategy for atherosclerotic neovascularization.

Octanoylated ghrelin attenuates angiogenesis induced by oxLDL in human coronary artery endothelial cells via the GHSR1a-mediated NF-κB pathway

OBJECTIVE

Low concentrations of oxidized low-density lipoprotein (oxLDL) promote the in vitro angiogenesis of endothelial cells and play an important role in plaque angiogenesis, which may cause plaque vulnerability and enhance the risk of intravascular thrombosis. The aim of this research was to investigate the effects of octanoylated ghrelin on oxLDL-induced angiogenesis and the underlying molecular mechanisms involved in this process.

MATERIALS/METHODS

Human coronary artery endothelial cells (HCAECs) were incubated with 5 μg/ml oxLDL and treated with various concentrations of octanoylated ghrelin (10(-9)-10(-6)M) with or without inhibitors for 24h. Cell proliferation, migration, and in vitro angiogenesis were analyzed by bromodeoxyuridine (BrdU) staining and BrdU enzyme-linked immunosorbent assay (ELISA), transwell assay, and tube formation on Matrigel, respectively. NF-κB (nuclear factor κB) expression was determined by Western-blot analysis.

RESULTS

Treatment with oxLDL at 5 μg/ml enhanced the proliferation, migration and tube formation of HCAECs. In contrast, pretreatment with octanoylated ghrelin significantly attenuated in vitro angiogenesis in oxLDL-induced HCAECs. In addition, Western blot analysis indicated that NF-κB expression was increased after oxLDL treatment, and that this effect was significantly reversed by pretreatment with octanoylated ghrelin. However, the NF-κB inhibitor PDTC or the GHSR1a inhibitor [D-Lys3]-GHRP-6 abolished the effects of octanoylated ghrelin on the inhibition of angiogenesis and NF-κB p65 expression induced by oxLDL.

CONCLUSIONS

These findings suggest that octanoylated ghrelin attenuates angiogenesis induced by oxLDL in HCAECs via the inhibition of GHSR1a-mediated NF-κB pathway. Furthermore, octanoylated ghrelin may promote the stability of vulnerable plaques by inhibiting plaque angiogenesis.