Endothelial cell Ass1 inhibits arteriosclerotic calcification in diabetes mellitus

Endothelial cell (EC) dysfunction is an important pathological feature of early calcification in diabetic plaques. Argininosuccinic synthase 1 (Ass1) is important in protecting EC activity. Therefore, this study aimed to explore the effect of endothelial Ass1 on calcification in diabetic plaques and its potential regulatory mechanism. In this study, serum Ass1 levels were measured in 84 patients, and the study showed that the serum Ass1 level in patients with diabetes was significantly decreased compared with the non-diabetic group, and the serum Ass1 level in patients with coronary artery calcification was significantly decreased compared with the non-coronary artery calcification group. The ApoE-/- mouse diabetic plaque calcification model and the mouse aortic endothelial cell (MAEC) calcification model were constructed, and the influence of endothelial cell Ass1 on diabetic plaque calcification was further investigated by adeno-associated virus and plasmid intervention. Molecular biology studies have shown that endothelial Ass1 overexpression can reduce plaque calcification and inhibit MAEC osteogenic differentiation in diabetic mice, and Ass1 has protective effects on EC and blood vessels in mice. 4D-label-free proteomic sequencing, bioinformatics analysis, and IP experiments were performed on ApoE-/- mouse aorta after adeno-associated virus intervention. It was found that the differential protein Ptk2b was closely related to vascular calcification (VC) and interacted with the target protein Ass1. The above studies indicate that endothelial Ass1 affects calcification formation in diabetic plaques, and the mechanism may be related to Ptk2b. Ass1 may be a new target for the treatment of diabetic VC.

Atherosclerosis Calcification: Focus on Lipoproteins

Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of lipids in the vessel wall, leading to the formation of an atheroma and eventually to the development of vascular calcification (VC). Lipoproteins play a central role in the development of atherosclerosis and VC. Both low- and very low-density lipoproteins (LDL and VLDL) and lipoprotein (a) (Lp(a)) stimulate, while high-density lipoproteins (HDL) reduce VC. Apolipoproteins, the protein component of lipoproteins, influence the development of VC in multiple ways. Apolipoprotein AI (apoAI), the main protein component of HDL, has anti-calcific properties, while apoB and apoCIII, the main protein components of LDL and VLDL, respectively, promote VC. The role of lipoproteins in VC is also related to their metabolism and modifications. Oxidized LDL (OxLDL) are more pro-calcific than native LDL. Oxidation also converts HDL from anti- to pro-calcific. Additionally, enzymes such as autotaxin (ATX) and proprotein convertase subtilisin/kexin type 9 (PCSK9), involved in lipoprotein metabolism, have a stimulatory role in VC. In summary, a better understanding of the mechanisms by which lipoproteins and apolipoproteins contribute to VC will be crucial in the development of effective preventive and therapeutic strategies for VC and its associated cardiovascular disease.

Expression of recombinant human Apolipoprotein A-IMilano in Nicotiana tabacum

Apolipoprotein A-IMilano (Apo A-IMilano) is a natural mutant of Apolipoprotein. It is currently the only protein that can clear arterial wall thrombus deposits and promptly alleviate acute myocardial ischemia. Apo A-IMilano is considered as the most promising therapeutic protein for treating atherosclerotic diseases without obvious toxic or side effects. However, the current biopharmaceutical platforms are not efficient for developing Apo A-IMilano. The objectives of this research were to express Apo A-IMilano using the genetic transformation ability of N. tabacum. The method is to clone the coding sequence of Apo A-IMilano into the plant binary expression vector pCHF3 with a Flag/His6/GFP tag. The constructed plasmid was transformed into N. tabacum by a modified agrobacterium-mediated method, and transformants were selected under antibiotic stress. PCR, RT-qPCR, western blot and co-localization analysis was used to further verify the resistant N. tabacum. The stable expression and transient expression of N. tabacum were established, and the pure product of Apo A-IMilano was obtained through protein A/G agarose. The results showed that Apo A-IMilano was expressed in N. tabacum with a yield of 0.05 mg/g leaf weight and the purity was 90.58% ± 1.65. The obtained Apo A-IMilano protein was subjected to amino acid sequencing. Compared with the theoretical sequence of Apo A-IMilano, the amino acid coverage was 86%, it is also found that Cysteine replaces Arginine at position 173, which indicates that Apo A-IMilano, a mutant of Apo A-I, is accurately expressed in N. tabacum. The purified Apo A-IMilano protein had a lipid binding activity. The established genetic modification N. tabacum will provide a cost-effective system for the production of Apo A-IMilano. Regarding the rapid propagation of N. tabacum, this system provides the possibility of large-scale production and accelerated clinical translation of Apo A-IMilano.

High-Density Lipoprotein and Long-Term Incidence and Progression of Aortic Valve Calcification: The Multi-Ethnic Study of Atherosclerosis

BACKGROUND

Aortic valve calcification (AVC) shares pathological features with atherosclerosis. Lipoprotein components have been detected in aortic valve tissue, including HDL (high-density lipoprotein). HDL measures have inverse associations with cardiovascular disease, but relationships with long-term AVC progression are unclear. We investigated associations of HDL cholesterol, HDL-particle number and size, apoC3-defined HDL subtypes, and, secondarily, CETP (cholesteryl ester transfer protein) mass and activity, with long-term incidence and progression of AVC.

METHODS

We used linear mixed-effects models to evaluate the associations of baseline HDL indices with AVC. AVC was quantified by Agatston scoring of up to 3 serial computed tomography scans over a median of 8.9 (maximum 11.2) years of follow-up in the Multi-Ethnic Study of Atherosclerosis (n=6784).

RESULTS

After adjustment, higher concentrations of HDL-C (high-density lipoprotein cholesterol), HDL-P (HDL particles), large HDL-P, and apoC3-lacking HDL-C were significantly associated with lower incidence/progression of AVC. Neither small or medium HDL-P nor apoC3-containing HDL-C was significantly associated with AVC incidence/progression. When included together, a significant association was observed only for HDL-C, but not for HDL-P. Secondary analyses showed an inverse relationship between CETP mass, but not activity, and AVC incidence/progression. In exploratory assessments, inverse associations for HDL-C, HDL-P, large HDL-P, and apoC3-lacking HDL with AVC incidence/progression were more pronounced for older, male, and White participants. ApoC3-containing HDL-C only showed a positive association with AVC in these subgroups.

CONCLUSIONS

In a multiethnic population, HDL-C, HDL-P, large HDL-P, and apoC3-lacking HDL-C were inversely associated with long-term incidence and progression of AVC. Further investigation of HDL composition and mechanisms could be useful in understanding pathways that slow AVC.

ApoC-III is a novel inducer of calcification in human aortic valves

Calcific aortic valve disease (CAVD) occurs when subpopulations of valve cells undergo specific differentiation pathways, promoting tissue fibrosis and calcification. Lipoprotein particles carry oxidized lipids that promote valvular disease, but low-density lipoprotein-lowering therapies have failed in clinical trials, and there are currently no pharmacological interventions available for this disease. Apolipoproteins are known promoters of atherosclerosis, but whether they possess pathogenic properties in CAVD is less clear. To search for a possible link, we assessed 12 apolipoproteins in nonfibrotic/noncalcific and fibrotic/calcific aortic valve tissues by proteomics and immunohistochemistry to understand if they were enriched in calcified areas. Eight apolipoproteins (apoA-I, apoA-II, apoA-IV, apoB, apoC-III, apoD, apoL-I, and apoM) were enriched in the calcific versus nonfibrotic/noncalcific tissues. Apo(a), apoB, apoC-III, apoE, and apoJ localized within the disease-prone fibrosa and colocalized with calcific regions as detected by immunohistochemistry. Circulating apoC-III on lipoprotein(a) is a potential biomarker of aortic stenosis incidence and progression, but whether apoC-III also induces aortic valve calcification is unknown. We found that apoC-III was increased in fibrotic and calcific tissues and observed within the calcification-prone fibrosa layer as well as around calcification. In addition, we showed that apoC-III induced calcification in primary human valvular cell cultures via a mitochondrial dysfunction/inflammation-mediated pathway. This study provides a first assessment of a broad array of apolipoproteins in CAVD tissues, demonstrates that specific apolipoproteins associate with valvular calcification, and implicates apoC-III as an active and modifiable driver of CAVD beyond its potential role as a biomarker.

A Compendium of the Biological Effects of Apolipoprotein A-IMilano

Obesity is a pathologic condition generated by an energy imbalance, that is, excess caloric consumption, leading to weight gain and metabolic disturbances characterized by adipose tissue inflammation and hyperglycemic conditions. In line with these observations, increasing evidence causally links inflammation, or the molecules and networks integral to inflammatory response, to the development of obesity and the complications that emerge from this pathology, such as cardiovascular, neurologic, respiratory, and metabolic illnesses, as well as sepsis and cancer. Not surprisingly, this chronic and abnormal metabolic background leads to constant derangements in innate and adaptive immunity. It is well known that high-density lipoprotein (HDL) possesses anti-inflammatory and antioxidant properties, and various studies have highlighted an emerging role of HDL in modulating immune function. The efficacy of synthetic HDL (sHDL) containing the recombinant form of apoA-IMilano (sHDL-apoA-IM), originating from the observation that carriers of this mutation have low levels of HDL cholesterol without increased atherosclerosis, has been largely proved in diverse animal models of atherosclerosis; however, the therapeutic use of sHDL-apoA-IM still needs clinical validation. One of the main limitations to the use of recombinant proteins in clinical studies lies in the unsustainable purification costs. Unpurified rice-milk-apoA-IM demonstrated anti-inflammatory and antiatherogenic properties in a mouse model, even though administrated by an unconventional way: by oral gavage. Additionally, recent data have uncovered new therapeutic applications for this sHDL-apoA-IM This review provides an overview of all potential application of sHDL-apoA-IM in some inflammatory-based diseases. SIGNIFICANCE STATEMENT: A recent study demonstrated that oral administration of rice-seed protein extracts containing the apoA-IM (i.e., the milk-apoA-IM) reduced atherosclerosis development in a mouse model. Moreover, the rice-milk-apoA-IM preserved both in vitro and in vivo anti-inflammatory properties, as observed when sHDL-apoA-IM was given by intravascular infusion. Besides, various studies suggested that sHDL-apoA-IM could positively affect other inflammatory-based diseases. Together, these data might represent a new starting point for "sHDL-apoA-IM-based therapies" in chronic degenerative disease.

Plaque Calcification

Vascular calcification (VC) is strongly associated with all-cause mortality and is an independent predictor of cardiovascular events. Resulting from its complex, multifaceted nature, targeted treatments for VC have not yet been developed. Lipoproteins are well characterized in the pathogenesis of atherosclerotic plaques, leading to the development of plaque regressing therapeutics. Although their roles in plaque progression are well documented, their roles in VC, and calcification of a plaque, are not well understood. In this review, early in vitro data and clinical correlations suggest an inhibitory role for HDL (high-density lipoproteins) in VC, a stimulatory role for LDL (low-density lipoprotein) and VLDL (very low-density lipoprotein) and a potentially causal role for Lp(a) (lipoprotein [a]). Additionally, after treatment with a statin or PCSK9 (proprotein convertase subtilisin/kexin type 9) inhibitor, plaque calcification is observed to increase. With the notion that differing morphologies of plaque calcification associate with either a more stable or unstable plaque phenotype, uncovering the mechanisms of lipoprotein-artery wall interactions could produce targeted therapeutic options for VC.

Progression of calcific aortic valve sclerosis in WHHLMI rabbits

BACKGROUND AND AIMS

Aortic valve stenosis (AS) is the most common valvular heart disease and can be life-threatening. The pathogenesis of aortic valve calcification remains largely unknown, primarily due to the lack of an adequate animal model. The high-cholesterol diet-induced AS model in rabbits is one of the established models, but it has the significant limitation of liver dysfunction leading to low survival rates. We hypothesized that a myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbit, an animal model of familial hypercholesterolemia and atherosclerosis, is a useful animal model of AS.

METHODS

WHHLMI rabbits, aged 20 months and 30 months (n = 19), and control Japanese White rabbits (n = 4), aged 30 months, were used and evaluated by echocardiography under anesthesia. Pathological evaluation and quantitative analyses by polymerase chain reaction (PCR) were also performed.

RESULTS

The lipid profile was similar between 20 months and 30 months. Two rabbits died due to spontaneous myocardial infarction during the study. Thirty-month-old WHHLMI rabbits exhibited significantly smaller aortic valve area (0.22 ± 0.006 cm²vs. 0.12 ± 0.01 cm², p < 0.05) and higher maximal transvalvular pressure gradient (7.0 ± 0.32 vs. 9.9 ± 0.95 mmHg, p < 0.05) than 20 month-old rabbits. Macroscopic examination of excised aortic valves demonstrated thickened and degenerated valve leaflets at 30 months. Histological evaluation confirmed thickened leaflets with calcified nodules at 30 months. Real-time PCR of resected aortic valve also showed increased expression level of calcification-related molecules including osteopontin, Sox9, Bmp2, RANKL, osteoprotegerin, and Runx2 (p < 0.05 each) in 30-month-old rabbits.

CONCLUSIONS

WHHLMI rabbits may be useful models of early-stage AS in vivo.

[Pharmacological targets for dislipidemies correction. Opportunities and prospects of therapeutic usage]

Literature data on influence of existing and new groups of drug preparations for dyslipidemias correction are systemized, and molecular mechanisms of their effects are reviewed. The results of experimental and clinical investigations aimed at revealing of new pharmacological targets of dyslipidemias correction were analyzed. The approaches for activation of high density lipoproteins functionality are described. The implementation of alternative preparations with new alternative mechanisms of action may be suggested to improve the effectiveness of traditional treatment in the future.

Pioglitazone Attenuates Atherosclerosis in Diabetic Mice by Inhibition of Receptor for Advanced Glycation End-Product (RAGE) Signaling

Background

Peroxisome proliferator-activated receptor-γ (PPAR-γ) exhibits anti-inflammatory and anti-diabetic properties, and is protective against cardiovascular diseases. This study aimed to determine the effects of a PPAR-γ agonist pioglitazone on atherogenesis in an ApoE knockout mouse (ApoE^−/−) diabetic mouse model and in a cultured vascular smooth muscle cells (VSMCs) model.

Material/Methods

Male ApoE^−/− mice were rendered diabetic by 5 daily intraperitoneal injections of streptozotocin. Pioglitazone (20 mg/kg/d) or PPAR-γ inhibitor GW9662 (1 mg/kg/d) were administered for 12 weeks. At the end of treatment, mice were killed and the aortae were isolated. Oil Red O staining was used to evaluate atherosclerotic plaque area. H&E staining was used to evaluate the number of complicated plaques. Western blotting and immunohistochemistry were used to determine the expression of advanced glycation end-products (RAGE) and PPAR-γ. The effects of pioglitazone and GW9662 on RAGE and PPAR-γ expression were examined in cultured primary mouse VSMCs in hyperglycemic conditions.

Results

Administration of pioglitazone in diabetic ApoE^−/− mice successfully reduced atherosclerotic plaque area and the number of complicated plaques. Moreover, pioglitazone inhibited RAGE and stimulated PPAR-γ protein expression in atherosclerotic plaques of diabetic ApoE^−/− mice. In cultured VSMCs upon high-glucose challenge, pioglitazone downregulated RAGE mRNA and protein expression. Blockade of PPAR-γ activity by GW9662 remarkably attenuated the inhibitory actions of pioglitazone on atherogenesis, both in diabetic ApoE^−/− mice and in cultured VSMCs, upon high-glucose challenge.

Conclusions

Pioglitazone has a therapeutic effect on atherosclerosis in diabetes, and inhibition of RAGE signaling plays a critical role in mediating the beneficial effects of pioglitazone.

Intravenous treatment with human recombinant ApoA-I Milano reduces beta amyloid cerebral deposition in the APP23-transgenic mouse model of Alzheimer's disease

Beyond the crucial role of apolipoprotein A-I (ApoA-I) on peripheral cholesterol metabolism, this apolipoprotein has also been implicated in beta amyloid (Aβ)-related neuropathologies. ApoA-I-Milano (M) is a mutated variant, which showed increased vasoprotective properties compared to ApoA-I-wild type in models of atherosclerosis and cardiovascular damage. We speculated that ApoA-I-M may also protect Aβ-affected vasculature and reverse some of the pathological features associated with Alzheimer's disease (AD). For this purpose, we produced and characterized human recombinant ApoA-I-wild type and ApoA-I-M proteins. Both of them were able to avoid the aggregation of Aβ in vitro, even though recombinant ApoA-I-M was significantly more effective in protecting endothelial cells from Aβ(1-42)-toxicity. Next, we determined the effect of chronic intravenous administration of rApoA-I-M in the APP23-transgenic mouse model of AD. We found reduced cerebral Aβ levels in mice that received rApoA-I-M, which were accompanied by a lower expression of astrocyte and microglia neuroinflammatory markers. Our results suggest an applicability of this molecule as a therapeutic candidate for protecting the brain in AD.

Medical Treatment of Aortic Stenosis

Untreated, severe, symptomatic aortic stenosis is associated with a dismal prognosis. The only treatment shown to improve survival is aortic valve replacement; however, before symptoms occur, aortic stenosis is preceded by a silent, latent phase characterized by a slow progression at the molecular, cellular, and tissue levels. In theory, specific medical therapy should halt aortic stenosis progression, reduce its hemodynamic repercussions on left ventricular function and remodeling, and improve clinical outcomes. In the present report, we performed a systematic review of studies focusing on the medical treatment of patients with aortic stenosis. Lipid-lowering therapy, antihypertensive drugs, and anticalcific therapy have been the main drug classes studied in this setting and are reviewed in depth. A critical appraisal of the preclinical and clinical evidence is provided, and future research avenues are presented.

Infusional high-density lipoproteins therapies as a novel strategy for treating atherosclerosis

High-density lipoproteins (HDL) have received considerable interest as a target for the development of novel anti-atherosclerotic agents beyond conventional approaches to lipid lowering. While a number of approaches have focused on modifying remodeling and expression pathways implicated in the regulation of HDL levels, an additional approach involves simply infusions of delipidated HDL. Several groups have advanced HDL infusions to clinical development with intriguing signs suggesting potentially favorable impacts at the level of the artery wall. The findings of early studies of infusional HDL therapies will be reviewed.

HDL mimetic peptide CER-522 treatment regresses left ventricular diastolic dysfunction in cholesterol-fed rabbits

OBJECTIVES

High-density lipoprotein (HDL) infusions induce rapid improvement of experimental atherosclerosis in rabbits but their effect on ventricular function remains unknown. We aimed to evaluate the effects of the HDL mimetic peptide CER-522 on left ventricular diastolic dysfunction (LVDD).

METHODS

Rabbits were fed with a cholesterol- and vitamin D2-enriched diet until mild aortic valve stenosis and hypercholesterolemia-induced LV hypertrophy and LVDD developed. Animals then received saline or 10 or 30mg/kg CER-522 infusions 6 times over 2weeks. We performed serial echocardiograms and LV histology to evaluate the effects of CER-522 therapy on LVDD.

RESULTS

LVDD was reduced by CER-522 as shown by multiple parameters including early filling mitral deceleration time, deceleration rate, Em/Am ratio, E/Em ratio, pulmonary venous velocities, and LVDD score. These findings were associated with reduced macrophages (RAM-11 positive cells) in the pericoronary area and LV, and decreased levels of apoptotic cardiomyocytes in CER-522-treated rabbits. CER-522 treatment also resulted in decreased atheromatous plaques and internal elastic lamina area in coronary arteries.

CONCLUSIONS

CER-522 improves LVDD in rabbits, with reductions of LV macrophage accumulation, cardiomyocyte apoptosis, coronary atherosclerosis and remodelling.

Lipid Interventions in Aortic Valvular Disease

Aortic valve stenosis is the most common valvular disease in the elderly population. Presently, there is increasing evidence that aortic stenosis (AS) is an active process of lipid deposition, inflammation, fibrosis and calcium deposition. The pathogenesis of AS shares many similarities to that of atherosclerosis; therefore, it was hypothesized that certain lipid interventions could prevent or slow the progression of aortic valve stenosis. Despite the early enthusiasm that statins may slow the progression of AS, recent large clinical trials did not consistently demonstrate a decrease in the progression of AS. However, some researchers believe that statins may have a benefit early on in the disease process, where inflammation (and not calcification) is the predominant process, in contrast to severe or advanced AS, where calcification (and not inflammation) predominates. Positron emission tomography using 18F-fluorodeoxyglucose and 18F-sodium fluoride can demonstrate the relative contributions of valvular calcification and inflammation in AS, and thus this method might potentially be useful in providing the answer as to whether lipid interventions at the earlier stages of AS would be more effective in slowing the progression of the disease. Currently, there is a strong interest in recombinant apolipoprotein A-1 Milano and in the development of new pharmacological agents, targeting reduction of lipoprotein (a) levels and possibly reduction of the expression of lipoprotein-associated phospholipase A2, as potential means to slow the progression of aortic valvular stenosis.

High-mobility group box-1 protein induces osteogenic phenotype changes in aortic valve interstitial cells

OBJECTIVES

Calcific aortic valve (AV) disease is known to be an inflammation-related process. High-mobility group box-1 (HMGB1) protein and Toll-like receptor 4 (TLR4) have been reported to participate in several inflammatory diseases. The purpose of the present study was to determine whether the HMGB1-TLR4 axis is involved in calcific AV disease, and to evaluate the effect of HMGB1, and its potential mechanisms, on the pro-osteogenic phenotype change of valvular interstitial cells (VICs).

METHODS

Expression of HMGB1 and TLR4 in human calcific AVs was evaluated using immunohistochemical staining and immunoblotting. Cultured VICs were used as an in vitro model. The VICs were stimulated with HMGB1 for analysis, with versus without TLR4 small interfering ribonucleic acid (siRNA), c-Jun N-terminal kinase mitogen-activated protein kinase (JNK MAPK), and nuclear factor kappa-B (NF-κB) inhibitors.

RESULTS

Enhanced accumulation of HMGB1 and TLR4 was observed in calcific valves. Moreover, we found that HMGB1 induced high levels of pro-inflammatory cytokine production and promoted the osteoblastic differentiation and calcification of VICs. In addition, HMGB1 induced phosphorylation of JNK MAPK and NF-κB. However, these effects were markedly suppressed by siRNA silencing of TLR4. In addition, blockade of JNK MAPK and NF-κB phosphorylation prohibited HMGB1-induced production of pro-osteogenic factors, and mineralization of VICs.

CONCLUSIONS

The HMGB1 protein may promote osteoblastic differentiation and calcification of VICs, through the TLR4-JNK-NF-κB signaling pathway.

Recombinant HDL (Milano) protects endotoxin-challenged rats from multiple organ injury and dysfunction

Endotoxemia, the systemic inflammatory host response to infection, leads to severe septic shock and multiple organ injury and dysfunction syndrome (MOPS), which cause mortality. Apolipoprotein A-IMilano (apoAIM), a naturally occurring cysteine mutant of apoAI with dimers as its effective form, showed an enhanced cardiovascular protective activity compared with wild-type apoAI (apoAIwt). To investigate the role of recombinant high-density lipoprotein (rHDL) reconstituted with apoAIM (rHDLM) on endotoxemia and MOPS, we examined the anti-inflammatory, anti-oxidant, and protective effects of this cysteine mutant against organ injury in endotoxin-challenged rat models compared with rHDLwt. In the present study, we demonstrated for the first time that pretreatment with rHDLM significantly attenuated liver and renal dysfunction and histopathological features of lung injury in endotoxin-challenged endotoxemia rats. Administration of rHDLM to endotoxemia rats dramatically suppressed proinflammatory cytokines and adhesion molecule increase in tumor necrosis factor α, interleukin 1β, interleukin 6, and intercellular adhesion molecule 1. In addition, rHDLM pretreatment inhibited lipid peroxidation and enhanced total antioxidant capacity in vivo. In comparison with rHDLwt, rHDLM showed enhanced capacity on anti-inflammatory and anti-oxidant functions. In summary, administration of rHDLM protected endotoxin-challenged endotoxemia and MOPS through enhanced anti-inflammatory and anti-oxidant properties.

Light to Moderate Alcohol Consumption Is Associated With Lower Risk of Aortic Valve Sclerosis: The Study of Health in Pomerania (SHIP)

OBJECTIVE

In developed countries, sclerotic and calcific degeneration of the aortic valve is a common disorder showing pathophysiologic similarities with atherothrombotic coronary disease. Light to moderate alcohol consumption has been associated with a lower risk for atherothrombotic coronary disease and mortality. Whether alcohol consumption affects the development of aortic valve sclerosis (AVS) is not well known. In the present study, we aim to analyze the cross-sectional association between average daily alcohol consumption and AVS in the general population.

APPROACH AND RESULTS

We analyzed cross-sectional data from 2022 men and women, aged 45 to 81 years, from the population-based Study of Health in Pomerania. We used a computer-assisted interview that included beverage-specific questions about quantity and frequency of alcohol over the last 30 days to calculate the average quantity of alcohol consumption (in grams of ethanol per day). AVS was ascertained by echocardiography. The prevalence of AVS was 32.3%. Average daily alcohol intake displayed a J-type relation with AVS (fully adjusted P value: 0.005). Compared with individuals with an average consumption of 10 g of alcohol per day, multivariable-adjusted odds ratios were 1.60 (95% confidence interval, 1.19-2.14) among current abstainers and 1.56 (95% confidence interval, 1.01-2.41) among individuals with an average consumption of 60 g per day.

CONCLUSIONS

Our findings indicate that light to moderate alcohol consumption was associated with a lower odd of having AVS. Prospective data need to address whether alcohol consumption and related changes over time in several biological markers affect the progression of AVS.

Rosiglitazone attenuates atherosclerosis and increases high-density lipoprotein function in atherosclerotic rabbits

Rosiglitazone has been found to have anti-atherogenic effects and to increase serum high-density lipoprotein (HDL) cholesterol (HDL-C) levels. However, in vivo studies investigating the regulation of adenosine triphosphate-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI) by rosiglitazone are limited. Moreover, the effects of rosiglitazone on the function and levels of HDL are unclear. In the present study, we investigated the effects of rosiglitazone on HDL function and its mechanisms of action in atherosclerotic rabbits. Our results revealed that rosiglitazone induced a significant increase in serum HDL-C levels, paraoxonase 1 (PON1) activity, [³H]cholesterol efflux rates, and the expression of ABCA1 and SR-BI in hepatocytes and peritoneal macrophages. The expression of ABCA1 was also increased in aortic lesions. Rosiglitazone markedly reduced serum myeloperoxidase (MPO) activity, aortic intima-media thickness (IMT) and the percentage of plaque area in the aorta. It can thus be concluded that in atherosclerotic rabbits, rosigitazone increases the levels of HDL-C and hinders atherosclerosis. Thus, it improves HDL quality and function, as well as the HDL-induced cholesterol efflux, exerting anti-inflammatory and antioxidant effects.

Oxidized Low-Density Lipoprotein Promotes Osteoblastic Differentiation of Valvular Interstitial Cells through RAGE/MAPK

Objectives: We have previously shown that oxidized low-density lipoprotein (oxLDL) promotes the osteogenic differentiation of valvular interstitial cells (VICs) by inducing endoplasmic reticulum (ER) stress. We also demonstrated the detrimental role of the receptor for advanced glycation end products (RAGE) activation and signaling in the development and progression of aortic valve (AV) calcification. Here, we test the hypothesis that oxLDL may induce the osteoblastic differentiation of VICs via RAGE. Methods: Cultured porcine aortic VICs were used in an in vitro model. The VICs were incubated with oxLDL for analysis, with and without RAGE siRNA. Results: We found that oxLDL markedly increased the expression of RAGE, induced high levels of proinflammatory cytokine production and promoted the osteoblastic differentiation and calcification of VICs. oxLDL also induced phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK) MAPK. However, these effects were found to be markedly suppressed by siRNA silencing of RAGE. Conclusions: Our data provide evidence that RAGE mediates oxLDL-induced activation of p38 and JNK MAPK and the osteogenic differentiation of VICs.

Improvement of aortic valve stenosis by ApoA-I mimetic therapy is associated with decreased aortic root and valve remodelling in mice

BACKGROUND AND PURPOSE

We have shown that infusions of apolipoprotein A-I (ApoA-I) mimetic peptide induced regression of aortic valve stenosis (AVS) in rabbits. This study aimed at determining the effects of ApoA-I mimetic therapy in mice with calcific or fibrotic AVS.

EXPERIMENTAL APPROACH

Apolipoprotein E-deficient (ApoE(-/-) ) mice and mice with Werner progeria gene deletion (Wrn(Δhel/Δhel) ) received high-fat diets for 20 weeks. After developing AVS, mice were randomized to receive saline (placebo group) or ApoA-I mimetic peptide infusions (ApoA-I treated groups, 100 mg·kg(-1) for ApoE(-/-) mice; 50 mg·kg(-1) for Wrn mice), three times per week for 4 weeks. We evaluated effects on AVS using serial echocardiograms and valve histology.

KEY RESULTS

Aortic valve area (AVA) increased in both ApoE(-/-) and Wrn mice treated with the ApoA-I mimetic compared with placebo. Maximal sinus wall thickness was lower in ApoA-I treated ApoE(-/-) mice. The type I/III collagen ratio was lower in the sinus wall of ApoA-I treated ApoE(-/-) mice compared with placebo. Total collagen content was reduced in aortic valves of ApoA-I treated Wrn mice. Our 3D computer model and numerical simulations confirmed that the reduction in aortic root wall thickness resulted in improved AVA.

CONCLUSIONS AND IMPLICATIONS

ApoA-I mimetic treatment reduced AVS by decreasing remodelling and fibrosis of the aortic root and valve in mice.

Molecular biology of calcific aortic valve disease: towards new pharmacological therapies

Calcific aortic valve disease (CAVD) is a chronic process leading to fibrosis and mineralization of the aortic valve. Investigations in the last several years have emphasized that key underlying molecular processes are involved in the pathogenesis of CAVD. In this regard, the processing of lipids and their retention has been underlined as an important mechanism that triggers inflammation. In turn, inflammation promotes/enhances the mineralization of valve interstitial cells, the main cellular component of the aortic valve. On the other hand, transformation of valve interstitial cells into myofibroblasts and osteoblast-like cells is determined by several signaling pathways having reciprocal cross-talks. In addition, the mineralization of the aortic valve has been shown to rely on ectonucleotidase and purinergic signaling. In this review, the authors have highlighted key molecular underpinnings of CAVD that may have significant relevance for the development of novel pharmaceutical therapies.

Potential drug targets for calcific aortic valve disease

Calcific aortic valve disease (CAVD) is a major contributor to cardiovascular morbidity and mortality and, given its association with age, the prevalence of CAVD is expected to continue to rise as global life expectancy increases. No drug strategies currently exist to prevent or treat CAVD. Given that valve replacement is the only available clinical option, patients often cope with a deteriorating quality of life until diminished valve function demands intervention. The recognition that CAVD results from active cellular mechanisms suggests that the underlying pathways might be targeted to treat the condition. However, no such therapeutic strategy has been successfully developed to date. One hope was that drugs already used to treat vascular complications might also improve CAVD outcomes, but the mechanisms of CAVD progression and the desired therapeutic outcomes are often different from those of vascular diseases. Therefore, we discuss the benchmarks that must be met by a CAVD treatment approach, and highlight advances in the understanding of CAVD mechanisms to identify potential novel therapeutic targets.

Evaluation of Links Between High-Density Lipoprotein Genetics, Functionality, and Aortic Valve Stenosis Risk in Humans

Objective—

Studies have shown that high-density lipoprotein (HDL)–raising compounds induce regression of aortic valve stenosis (AVS) in animal models. However, whether patients with AVS have an impaired HDL metabolism is unknown.

Approach and Results—

A total of 1435 single nucleotide polymorphisms in genes associated with HDL cholesterol levels (in or around GALNT2, LPL, ABCA1, APOA5, SCARB1, LIPC, CETP, LCAT, LIPG, APOC4 , and PLTP ) were genotyped in 382 patients with echocardiography-confirmed AVS (aortic jet velocity ≥2.5 m/s) and 401 controls. After control for multiple testing, none of the genetic variants showed a positive association with case/control status (adjusted P ≥0.05 for all single nucleotide polymorphisms tested). In a subsample of this cohort, HDL cholesterol levels, apolipoprotein AI levels, lecithin-cholesterol acyltransferase activity, pre–β-HDL, HDL size, and 4 parameters of cholesterol efflux capacity were measured in apolipoprotein B–depleted serum samples from 86 patients with and 86 patients without AVS. Cholesterol efflux capacity was measured using J774 macrophages with and without stimulation of ATP-binding cassette A-1 expression by cAMP, and HepG2 hepatocytes for scavenger receptor class B type 1–mediated efflux. None of these parameters were different between cases and controls. However, compared with patients without coronary artery disease, sera from patients with coronary artery disease had lower HDL cholesterol levels, scavenger receptor class B type 1–mediated efflux, and HDL size ( P ≤0.003), independently of the presence or absence of AVS.

Conclusions—

Results of the present study suggest that, based on HDL genetics and HDL functionality, HDL metabolism does not seem to predict the risk of AVS. Because of our limited sample size, additional studies are needed to confirm these findings.

The combination of L-4F and simvastatin stimulate cholesterol efflux and related proteins expressions to reduce atherosclerotic lesions in apoE knockout mice

Background

Both L-4F, one apolipoprotein A-1 mimetic peptide, and statins can reduce progression of atherosclerosis by different mechanisms. The combination of the two drugs can cause lesion regression by rendering HDL anti-inflammatory. We postulated that combination of L-4F and simvastatin may stimulate cholesterol efflux and related proteins expressions to alleviate atherosclerosis.

Methods

Thirty male wild-type (W-T) C57 BL/6 mice and apo E^−/− mice were divided into five groups: W-T group, atherosclerosis (AS) group, simvastatin group, L-4F group and the combination of simvastatin and L-4F group. After 16 weeks, serum lipids, atherosclerotic lesion areas, cholesterol efflux and the expressions of related proteins including ABCA1, SR-BI, ABCG1, LXRα and PPARγ were evaluated.

Results

The aortic atherosclerotic lesion areas were reduced more significantly by combination of both drugs than single agent, and cholesterol efflux was promoted more in combination group than simvastatin and L-4F group. Besides, the combination group promoted expressions of cholesterol efflux related proteins.

Conclusions

The combination of L-4F and simvastatin reduced atherosclerotic lesions, which stimulates cholesterol efflux by promoting the expressions of related proteins. In addition, these results help us further understand that the regression of the atherosclerosis would be assessed by reduction in LDL-C with increase of cholesterol efflux.

Structural basis for distinct functions of the naturally occurring Cys mutants of human apolipoprotein A-I

HDL removes cell cholesterol and protects against atherosclerosis. ApoA-I provides a flexible structural scaffold and an important functional ligand on the HDL surface. We propose structural models for apoA-I(Milano) (R173C) and apoA-I(Paris) (R151C) mutants that show high cardioprotection despite low HDL levels. Previous studies established that two apoA-I molecules encircle HDL in an antiparallel, helical double-belt conformation. Recently, we solved the atomic structure of lipid-free Δ(185-243)apoA-I and proposed a conformational ensemble for apoA-I(WT) on HDL. Here we modify this ensemble to understand how intermolecular disulfides involving C173 or C151 influence protein conformation. The double-belt conformations are modified by belt rotation, main-chain unhinging around Gly, and Pro-induced helical bending, and they are verified by comparison with previous experimental studies and by molecular dynamics simulations of apoA-I(Milano) homodimer. In our models, the molecular termini repack on various-sized HDL, while packing around helix-5 in apoA-I(WT), helix-6 in apoA-I(Paris), or helix-7 in apoA-I(Milano) homodimer is largely conserved. We propose how the disulfide-induced constraints alter the protein conformation and facilitate dissociation of the C-terminal segment from HDL to recruit additional lipid. Our models unify previous studies of apoA-I(Milano) and demonstrate how the mutational effects propagate to the molecular termini, altering their conformations, dynamics, and function.

Apolipoprotein A-I inhibits LPS-induced atherosclerosis in ApoE(-/-) mice possibly via activated STAT3-mediated upregulation of tristetraprolin

AIM

To investigate the effects of the major component of high-density lipoprotein apolipoprotein A-I (apoA-I) on the development of atherosclerosis in LPS-challenged ApoE(-/-) mice and the underlying mechanisms.

METHODS

Male ApoE-KO mice were daily injected with LPS (25 μg, sc) or PBS for 4 weeks. The LPS-challenged mice were intravenously injected with rAAV-apoA-I-GFP or rAAV-GFP. After the animals were killed, blood, livers and aortas were collected for biochemical and histological analyses. For ex vivo experiments, the abdominal cavity macrophages were harvested from each treatment group of mice, and cultured with autologous serum, then treated with LPS.

RESULTS

Chronic administration of LPS in ApoE(-/-) mice significantly increased the expression of inflammatory cytokines (TNF-α, IL-1β, IL-6, and MCP-1), increased infiltration of inflammatory cells, and enhanced the development of atherosclerosis. In LPS-challenged mice injected with rAAV-apoA-I-GFP, viral particles and human apoA-I were detected in the livers, total plasma human apoA-I levels were grammatically increased; HDL-cholesterol level was significantly increased, TG and TC were slightly increased. Furthermore, overexpression of apoA-I significantly suppressed the expression of proinflammatory cytokines, reduced the infiltration of inflammatory cells, and decreased the extent of atherosclerotic lesions. Moreover, overexpression of apoA-I significantly increased the expression of the cytokine mRNA-destabilizing protein tristetraprolin (TTP), and phosphorylation of JAK2 and STAT3 in aortas. In ex vivo mouse macrophages, the serum from mice overexpressing apoA-I significantly increased the expression of TTP, accompanied by accelerated decay of mRNAs of the inflammatory cytokines.

CONCLUSION

ApoA-I potently suppresses LPS-induced atherosclerosis by inhibiting the inflammatory response possibly via activation of STAT3 and upregulation of TTP.

Pioglitazone attenuates progression of aortic valve calcification via down-regulating receptor for advanced glycation end products

Receptor for advanced glycation end products (RAGE) is associated with inflammation and the progression of cardiovascular diseases. The current study tested the hypothesis that RAGE is involved in the pathogenesis of aortic valve (AV) calcification. Pioglitazone attenuated AV calcification in experimental hypercholesterolemic rabbits via down-regulation of RAGE. Male New Zealand rabbits weighing 2.5-3.0 kg were randomly divided into three groups: control group, high cholesterol + vitamin D(2) (HC + vitD(2)) group and HC + vitD(2) supplemented with pioglitazone group. Compared with HC + vitD(2) group, pioglitazone significantly inhibited the progression of AV calcification assessed by echocardiography. HC + vitD(2) diet markedly increased RAGE expression, oxidative stress, inflammatory cells infiltration and osteopontin expression. These changes were also significantly attenuated by administration of pioglitazone. Cultured porcine aortic valve interstitial cells (VICs) were used as in vitro model. We found that advanced glycation end products of bovine serum albumin markedly increased the expression of RAGE, induced high levels of production of pro-inflammatory cytokines and promoted osteoblastic differentiation of VICs. However, these effects were found to be remarkably suppressed by siRNA silencing of RAGE and pioglitazone as well. Our data provide evidence that RAGE activation-induced inflammation promotes AV calcification in hypercholesterolemic rabbits, which can be attenuated by pioglitazone treatment. This beneficial effect is associated with remarkable down-regulation of RAGE expression.

Deficiency of NG2+ cells contributes to the susceptibility of stroke-prone spontaneously hypertensive rats

AIMS

The purpose of this study is to investigate whether the NG2(+) cells, a class of oligodendrocyte progenitor cells, is involved in the pathophysiology of stroke in stroke-prone spontaneously hypertensive rat (SHR-SP).

METHODS

SHR-SP, SHR, Wistar-Kyoto rats (WKY), and C57BJ/6 mice were used. Immunohistochemistry was conducted to evaluate the number of NG2(+) cells in frozen brain sections. Demyelination was evaluated by Sudan black staining and serum level of myelin basic protein. Middle cerebral artery occlusion (MCAO) was performed to prepare experimental stroke model.

RESULTS

The number of NG2(+) cells was significantly decreased in infarct core and increased in penumbra in WKY rats after MCAO. In brain sections of 6-month-old SHR-SP, the number of NG2(+) cells was significantly (P < 0.01) less than that in age-matched SHR and WKY rats. However, this phenomenon was not observed in 3-month-old rats. Demyelination was found in 6-month-old SHR-SP but not in 3-month-old SHR-SP. Pharmacological treatment of cuprizone in mice induced demyelination and enlargement of cerebral infarction after MCAO.

CONCLUSION

The decline of NG2(+) cells may cause demyelination and contribute to the susceptibility of SHR-SP to ischemic brain injury.

Animal models of organic heart valve disease

Heart valve disease is a frequently encountered pathology, related to high morbidity and mortality rates in industrialized and developing countries. Animal models are interesting to investigate the causality, but also underlying mechanisms and potential treatments of human valvular diseases. Recently, animal models of heart valve disease have been developed, which allow to investigate the pathophysiology, and to follow the progression and the potential regression of disease with therapeutics over time. The present review provides an overview of animal models of primary, organic heart valve disease: myxoid age-related, infectious, drug-induced, degenerative calcified, and mechanically induced valvular heart disease.

Probucol alleviates atherosclerosis and improves high density lipoprotein function

Background

Probucol is a unique hypolipidemic agent that decreases high density lipoprotein cholesterol (HDL-C). However, it is not definite that whether probucol hinders the progression of atherosclerosis by improving HDL function.

Methods

Eighteen New Zealand White rabbits were randomly divided into the control, atherosclerosis and probucol groups. Control group were fed a regular diet; the atherosclerosis group received a high fat diet, and the probucol group received the high fat diet plus probucol. Hepatocytes and peritoneal macrophages were isolated for [³H] labeled cholesterol efflux rates and expression of ABCA1 and SR-B1 at gene and protein levels; venous blood was collected for serum paraoxonase 1, myeloperoxidase activity and lipid analysis. Aorta were prepared for morphologic and immunohistochemical analysis after 12 weeks.

Results

Compared to the atherosclerosis group, the paraoxonase 1 activity, cholesterol efflux rates, expression of ABCA1 and SR-BI in hepatocytes and peritoneal macrophages, and the level of ABCA1 and SR-BI in aortic lesions were remarkably improved in the probucol group, But the serum HDL cholesterol concentration, myeloperoxidase activity, the IMT and the percentage plaque area of aorta were significantly decreased.

Conclusion

Probucol alleviated atherosclerosis by improving HDL function. The mechanisms include accelerating the process of reverse cholesterol transport, improving the anti-inflammatory and anti-oxidant functions.

Recombinant HDL(Milano) exerts greater anti-inflammatory and plaque stabilizing properties than HDL(wild-type)

OBJECTIVE

The aim of this study was to compare the effects of HDL(Milano) and HDL(wild-type), on regression and stabilization of atherosclerosis.

METHODS

Atherosclerotic New Zealand White rabbits received 2 infusions, 4 days apart, of HDL(Milano) (75mg/kg of apoA-I(Milano)), HDL(wild-type) (75mg/kg apoA-I(wild-type)) or placebo. Pre- and post-treatment plaque volume was assessed by MRI. Markers of plaque vulnerability and inflammation were evaluated. Liver and aortic cholesterol content, aortic ABCA-1 and liver SR-BI were quantified. The effect of apoA-I Milano and wild-type proteins on MCP-1 and COX-2 expression by macrophages was evaluated in vitro.

RESULTS

Both forms of HDL induced aortic plaque regression (-4.1% and -2.6% vs. pre-treatment in HDL(Milano) and HDL(wild-type) respectively, p<0.001 and p=0.009). A similar reduction in cholesterol content of aorta and liver was observed with both treatments vs. placebo. The expression of aortic ABCA-1 and hepatic SR-BI was significantly higher in both treated groups vs. placebo. A significantly reduced plaque macrophage density was observed in the HDL(Milano) vs. both HDL(wild-type) and placebo groups. Plaque levels of COX-2, MCP-1, Caspase-3 antigen and MMP-2 activity were significantly reduced in the HDL(Milano) vs. both HDL(wild-type) and placebo groups. In vitro studies showed that apoA-I(Milano) protein significantly reduced expression of COX-2 and MCP-1 in oxLDL loaded macrophages vs. apoA-I(wild-type).

CONCLUSIONS

Despite a similar effect on acute plaque regression, the infusion of HDL(Milano) exerts superior anti-inflammatory and plaque stabilizing effects than HDL(wild-type) in the short term.

Calcific aortic valve stenosis: methods, models, and mechanisms

Calcific aortic valve stenosis (CAVS) is a major health problem facing aging societies. The identification of osteoblast-like and osteoclast-like cells in human tissue has led to a major paradigm shift in the field. CAVS was thought to be a passive, degenerative process, whereas now the progression of calcification in CAVS is considered to be actively regulated. Mechanistic studies examining the contributions of true ectopic osteogenesis, nonosseous calcification, and ectopic osteoblast-like cells (that appear to function differently from skeletal osteoblasts) to valvular dysfunction have been facilitated by the development of mouse models of CAVS. Recent studies also suggest that valvular fibrosis, as well as calcification, may play an important role in restricting cusp movement, and CAVS may be more appropriately viewed as a fibrocalcific disease. High-resolution echocardiography and magnetic resonance imaging have emerged as useful tools for testing the efficacy of pharmacological and genetic interventions in vivo. Key studies in humans and animals are reviewed that have shaped current paradigms in the field of CAVS, and suggest promising future areas for research.

ETC-216 for coronary artery disease

INTRODUCTION

Increasing attention has focused on the role of high-density lipoprotein function as a target for cardiprotection. Apolipoprotein A-I(Milano) (AIM) involves a single amino-acid mutation of the major wild-type protein carried on high-density lipoprotein (HDL) particles. Early evidence of beneficial activities of AIM has stimulated support in its development as a potential therapy to reduce cardiovascular risk.

AREAS COVERED

The importance of HDL as a target and early data supporting the beneficial effects of AIM are reviewed. All clinical studies of AIM found in PubMed are reviewed.

EXPERT OPINION

ETC-216 represents a lipid-deplete form of HDL containing recombinant AIM. While early evidence suggests that administration of ETC-216 promotes rapid regression of coronary atherosclerosis, bringing this compound to clinical practice will require further trials that evaluate its impact on cardiovascular events.