The vascular biology of atherosclerosis and imaging targets

Plasma C-reactive protein is associated with a pro-inflammatory and adverse plaque phenotype

BACKGROUND AND AIMS

Systemic low-grade inflammation, measured by plasma high-sensitivity C-reactive protein (hsCRP) levels, is an important risk factor for atherosclerotic cardiovascular disease (ASCVD). To date, however, it is unknown whether plasma hsCRP is associated with adverse histological plaque features.

METHODS

Plaques were derived during carotid endarterectomy. Patients with hsCRP levels ≥2 mg/L were evaluated for pro-inflammatory and adverse plaque characteristics, as well as future ASCVD events, and compared with patients with low hsCRP levels. Logistic and linear regression analyses in addition to subdistribution hazard ratios were conducted, adjusted for cardiovascular risk factors.

RESULTS

A total of 1096 patients were included, of which 494 (46.2 %) had hsCRP levels ≥2 mg/L. Elevated hsCRP levels 2 mg/L were independently associated with levels of plaque interleukin 6, beta coefficient of 109.8 (95 % confidence interval (CI): 33.4, 186.5; p = 0.005) pg/L, interleukin 8 levels, 194.8 (110.4, 378.2; p = 0.03) pg/L and adiponectin plaque levels, -16.8 (-30.1, -3.6; p = 0.01) μg/L, compared with plaques from patients with low hsCRP levels. Histological analysis revealed increased vessel density in high hsCRP patients, odds ratio (OR) of 1.57 (1.20, 2.09; p = 0.001), larger lipid core, 1.35 (1.02, 1.73; p = 0.04), and increased macrophage content, 1.32 (1.02, 1.73; p = 0.04). Over a 3-year follow-up period, hsCRP levels ≥2 mg/L were associated with a hazard ratio of 1.81 (1.03, 3.16; p = 0.04) for coronary artery disease event risk.

CONCLUSIONS

The distinct inflammatory and histological features observed in carotid plaques among individuals with hsCRP levels ≥2 mg/L underscore the utility of plasma hsCRP as a potent identifier for patients harboring high-risk plaques.

CRP levels are significantly associated with CRP genotype and estrogen use in The Lifestyle, Biomarker and Atherosclerosis (LBA) study

Background

The C-reactive protein (CRP) is an important biomarker for atherosclerosis and single nucleotide polymorphisms (SNPs) in the CRP locus have been associated with altered CRP levels and associated with risk for cardiovascular disease. However, the association between genetic variations in the CRP gene, estrogen use and CRP levels or early signs of atherosclerosis in young healthy individuals is not fully characterized. We aimed to evaluate the influence of five genetic variants on both plasma CRP levels and carotid intima-media thickness (cIMT) values, including aspects on estrogen containing contraceptive use in females.

Methods

Genotyping was performed with TaqMan real time PCR and compared with high sensitivity CRP serum levels in 780 Swedish young, self-reported healthy individuals. Haplotypes of the SNPs were estimated with the PHASE v 2.1. The cIMT was measured by 12 MHz ultrasound. The contraceptive use was self-reported.

Results

Strong associations between CRP and genotype were observed for rs3091244, rs1800947, rs1130864, and rs1205 in women (all p < 0.001). In men, only rs1800947 was associated with CRP (p = 0.029). The independent effect of genotypes on CRP remained significant also after adjustment for established risk factors. Female carriers of the H1/ATGTG haplotype had higher CRP than non-carriers. This was specifically pronounced in the estrogen-using group (p < 0.001), and they had also higher cIMT (p = 0.002) than non-carriers but with a small cIMT difference between the haplotype groups (0.02 mm). In parallel, a significant correlation between CRP and cIMT in the estrogen using group was observed (r = 0.194; p = 0.026).

Conclusions

Estrogen use, genotypes and haplotypes in the CRP locus are significantly associated with CRP levels. Based on an observed interaction effect between sex/estrogen use and the H1/ATGTG haplotype on CRP, and a marginally thicker cIMT in the estrogen using group, our data suggest that both genotypes and estrogen usage could be involved in arterial wall structural differences. The causality between CRP levels and cIMT remains unclear, and the observed difference in cIMT is not clinically relevant in the present state. Future larger and longitudinal studies may shed further light on the role of more long-term estrogen use and early atherosclerosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02610-z.

P2X7 receptor-specific radioligand 18F-FTTM for atherosclerotic plaque PET imaging

PURPOSE

P2X7 receptors have been considered as a promising biomarker for vulnerable atherosclerotic plaques, which are highly expressed by that instability-associated factors such as macrophages. Thus, we aim to investigate the feasibility of using specific P2X7-targeted ¹⁸F-labeled tracer ¹⁸F-FTTM ((2-chloro-3-[¹⁸F]fluorophenyl)[1,4,6,7-tetrahydro-1-(2-pyrimidinyl)-5H-1,2,3-triazolo[4,5-c]pyridin-5-yl]methanone) for PET study of vulnerable atherosclerotic plaques identification.

METHOD

The radioligand ¹⁸F-FTTM was achieved based on the copper-mediated radiofluorination of arylstannane. In vitro and in vivo experiments were performed to verify the biochemical properties. Dynamic ¹⁸F-FTTM Micro-PET/CT imaging was performed for 1 h on ApoE^-/- mice (10, 20, 30 weeks on high-fat diet) and wild-type C57BL/6 J mice on normal diet. Ex vivo PET imaging was conducted to verify the specificity of the radioligand. Serum inflammatory cytokines, lipids, and lipoproteins profiles were detected by ELISA. The lipid distribution and morphology of plaques were evaluated by Oil Red O, HE, Masson, and immunofluorescence stainings.

RESULTS

¹⁸F-FTTM was afforded with decay-corrected radiochemical yields of 5-10%, specific activity of 269-320 MBq/nmol (n = 8, EOS), and radiochemical purity of above 99%. ¹⁸F-FTTM showed excellent stability in vitro, rapid blood clearance in mice, good affinity to RAW264.7 cells. We observed an increase in both in vivo and ex vivo imagings as disease progressed, and the imaging signatures correlated with histopathological features. Furthermore, compared with ¹⁸F-FDG imaging, the SUV_max values of ¹⁸F-FTTM at the aortic arch of ApoE^-/- mice of high-fat feeding for 20 and 30 weeks were 43% and 53% higher than those of the control group, respectively.

CONCLUSION

We innovatively apply a new type P2X7-targeted PET probe (¹⁸F-FTTM) to identify vulnerable atherosclerotic plaques, to detect the inflammatory response of atherosclerosis, and to provide a powerful non-invasive method for the diagnosis of atherosclerotic lesions and new drug screening for accurate treatment.

Endothelial Dysfunction in Atherosclerotic Cardiovascular Diseases and Beyond: From Mechanism to Pharmacotherapies

The endothelium, a cellular monolayer lining the blood vessel wall, plays a critical role in maintaining multiorgan health and homeostasis. Endothelial functions in health include dynamic maintenance of vascular tone, angiogenesis, hemostasis, and the provision of an antioxidant, anti-inflammatory, and antithrombotic interface. Dysfunction of the vascular endothelium presents with impaired endothelium-dependent vasodilation, heightened oxidative stress, chronic inflammation, leukocyte adhesion and hyperpermeability, and endothelial cell senescence. Recent studies have implicated altered endothelial cell metabolism and endothelial-to-mesenchymal transition as new features of endothelial dysfunction. Endothelial dysfunction is regarded as a hallmark of many diverse human panvascular diseases, including atherosclerosis, hypertension, and diabetes. Endothelial dysfunction has also been implicated in severe coronavirus disease 2019. Many clinically used pharmacotherapies, ranging from traditional lipid-lowering drugs, antihypertensive drugs, and antidiabetic drugs to proprotein convertase subtilisin/kexin type 9 inhibitors and interleukin 1β monoclonal antibodies, counter endothelial dysfunction as part of their clinical benefits. The regulation of endothelial dysfunction by noncoding RNAs has provided novel insights into these newly described regulators of endothelial dysfunction, thus yielding potential new therapeutic approaches. Altogether, a better understanding of the versatile (dys)functions of endothelial cells will not only deepen our comprehension of human diseases but also accelerate effective therapeutic drug discovery. In this review, we provide a timely overview of the multiple layers of endothelial function, describe the consequences and mechanisms of endothelial dysfunction, and identify pathways to effective targeted therapies. SIGNIFICANCE STATEMENT: The endothelium was initially considered to be a semipermeable biomechanical barrier and gatekeeper of vascular health. In recent decades, a deepened understanding of the biological functions of the endothelium has led to its recognition as a ubiquitous tissue regulating vascular tone, cell behavior, innate immunity, cell-cell interactions, and cell metabolism in the vessel wall. Endothelial dysfunction is the hallmark of cardiovascular, metabolic, and emerging infectious diseases. Pharmacotherapies targeting endothelial dysfunction have potential for treatment of cardiovascular and many other diseases.

Autoradiographical assessment of inflammation-targeting radioligands for atherosclerosis imaging: potential for plaque phenotype identification

PURPOSE

Many radioligands have been developed for the visualization of atherosclerosis by targeting inflammation. However, interpretation of in vivo signals is often limited to plaque identification. We evaluated binding of some promising radioligands in an in vitro approach in atherosclerotic plaques with different phenotypes.

METHODS

Tissue sections of carotid endarterectomy tissue were characterized as early plaque, fibro-calcific plaque, or phenotypically vulnerable plaque. In vitro binding assays for the radioligands [111In]In-DOTATATE; [111In]In-DOTA-JR11; [67Ga]Ga-Pentixafor; [111In]In-DANBIRT; and [111In]In-EC0800 were conducted, the expression of the radioligand targets was assessed via immunohistochemistry. Radioligand binding and expression of radioligand targets was investigated and compared.

RESULTS

In sections characterized as vulnerable plaque, binding was highest for [111In]In-EC0800; followed by [111In]In-DANBIRT; [67Ga]Ga-Pentixafor; [111In]In-DOTA-JR11; and [111In]In-DOTATATE (0.064 ± 0.036; 0.052 ± 0.029; 0.011 ± 0.003; 0.0066 ± 0.0021; 0.00064 ± 0.00014 %Added activity/mm2, respectively). Binding of [111In]In-DANBIRT and [111In]In-EC0800 was highest across plaque phenotypes, binding of [111In]In-DOTA-JR11 and [67Ga]Ga-Pentixafor differed most between plaque phenotypes. Binding of [111In]In-DOTATATE was the lowest across plaque phenotypes. The areas positive for cells expressing the radioligand's target differed between plaque phenotypes for all targets, with lowest percentage area of expression in early plaque sections and highest in phenotypically vulnerable plaque sections.

CONCLUSIONS

Radioligands targeting inflammatory cell markers showed different levels of binding in atherosclerotic plaques and among plaque phenotypes. Different radioligands might be used for plaque detection and discerning early from vulnerable plaque. [111In]In-EC0800 and [111In]In-DANBIRT appear most suitable for plaque detection, while [67Ga]Ga-Pentixafor and [111In]In-DOTA-JR11 might be best suited for differentiation between plaque phenotypes.

CC Chemokine Receptor 5 Targeted Nanoparticles Imaging the Progression and Regression of Atherosclerosis Using Positron Emission Tomography/Computed Tomography

Chemokines and chemokine receptors play an important role in the initiation and progression of atherosclerosis by mediating the trafficking of inflammatory cells. Chemokine receptor 5 (CCR5) has major implications in promoting the development of plaques to advanced stage and related vulnerability. CCR5 antagonist has demonstrated the effective inhibition of atherosclerotic progression in mice, making it a potential biomarker for atherosclerosis management. To accurately determine CCR5 in vivo, we synthesized CCR5 targeted Comb nanoparticles through a modular design and construction strategy with control over the physiochemical properties and functionalization of CCR5 targeting peptide d-Ala-peptide T-amide (DAPTA-Comb). In vivo pharmacokinetic evaluation through 64Cu radiolabeling showed extended blood circulation of 64Cu-DAPTA-Combs conjugated with 10%, 25%, and 40% DAPTA. The different organ distribution profiles of the three nanoparticles demonstrated the effect of DAPTA on not only physicochemical properties but also targeting efficiency. In vivo positron emission tomography/computed tomography (PET/CT) imaging in an apolipoprotein E knockout mouse atherosclerosis model (ApoE-/-) showed that the three 64Cu-DAPTA-Combs could sensitively and specifically detect CCR5 along the progression of atherosclerotic lesions. In an ApoE-encoding adenoviral vector (AAV) induced plaque regression ApoE-/- mouse model, decreased monocyte recruitment, CD68+ macrophages, CCR5 expression, and plaque size were all associated with reduced PET signals, which not only further confirmed the targeting efficiency of 64Cu-DAPTA-Combs but also highlighted the potential of these targeted nanoparticles for atherosclerosis imaging. Moreover, the up-regulation of CCR5 and colocalization with CD68+ macrophages in the necrotic core of ex vivo human plaque specimens warrant further investigation for atherosclerosis prognosis.

Nanoparticles target intimal macrophages in atherosclerotic lesions

Oxidized phosphatidylcholines (oxPCs) enriched on the oxidized LDL (oxLDL) surface are responsible ligands for binding oxLDL to the CD36 receptor of intimal macrophages in atherosclerotic lesions. We synthesized liposome-like nanoparticles (NPs) using soy phosphatidylcholine and incorporated 1-palmitoyl-2-(4-keto-dodec-3-enedioyl) phosphatidylcholine, a type of oxPCs, on their surface to make ligand-NP (L-NPs). The objectives of this study were to measure and compare their binding affinity to and uptake by primary mouse and THP-1 derived macrophages, and to determine their target specificity to intimal macrophages in aortic lesions in LDL receptor null (LDLr-/-) mice. All in vitro data demonstrate that L-NPs had a high binding affinity to macrophage CD36 receptor. L-NPs had 1.4-fold higher accumulation in aortic lesion areas than NPs. L-NPs co-localized with intimal macrophages and CD36 receptors in the aortic lesions. This target delivery approach may portend a breakthrough in molecular imaging and targeted treatment of atherosclerosis.

Reflections on Atherosclerosis: Lesson from the Past and Future Research Directions

The clinical manifestations of atherosclerosis are nowadays the main cause of death in industrialized countries, but atherosclerotic disease was found in humans who lived thousands of years ago, before the spread of current risk factors. Atherosclerotic lesions were identified on a 5300-year-old mummy, as well as in Egyptian mummies and other ancient civilizations. For many decades of the twentieth century, atherosclerosis was considered a degenerative disease, mainly determined by a passive lipid storage, while the most recent theory of atherogenesis is based on endothelial dysfunction. The importance of inflammation and immunity in atherosclerosis’s pathophysiology was realized around the turn of the millennium, when in 1999 the famous pathologist Russell Ross published in the New England Journal of Medicine an article entitled “Atherosclerosis – an inflammatory disease”. In the following decades, inflammation has been a topic of intense basic research in atherosclerosis, albeit its importance has ancient scientific roots. In fact, in 1856 Rudolph Virchow was the first proponent of this hypothesis, but evidence of the key role of inflammation in atherogenesis occurred only in 2017. It seemed interesting to retrace the key steps of atherosclerosis in a historical context: from the teachings of the physicians of the Roman Empire to the response-to-injury hypothesis, up to the key role of inflammation and immunity at various stages of disease. Finally, we briefly discussed current knowledge and future trajectories of atherosclerosis research and its therapeutic implications.

Effects of high-intensity interval training on endothelial function, lipid profile, body composition and physical fitness in normal-weight and overweight-obese adolescents: A clinical trial

Endothelium-aggressive factors are associated with the development of atherosclerosis. Exercise training can either prevent or attenuate this process, but little is known about the effects of high-intensity interval training (HIIT) in adolescents. Thus, we assessed the effects of HIIT on endothelial function, lipid profile, body composition and physical fitness in normal-weight and overweight-obese adolescents. Thirty-eight participants aged 14-17 years who were physically inactive (IPAq) were divided in two groups: normal weight (NW, n = 13) and overweight-obese (OW, n = 25). Body composition, lipid profile, physical fitness and endothelial function (flow-mediated dilation, FMD) were assessed before and after undergoing the study protocol consisting of 12-week HIIT (∼15 min) + sport activities (30 min, 3×/week) + no diet. The differences were tested by GEE, Bonferroni post-hoc, p < 0.05. There were no changes in body composition after training period, but the OW group showed a reduction in waist (4.8 cm; p = 0.044) and abdominal circumference (3.7 cm; p = 0.049). We found improved physical fitness (cardiorespiratory endurance, explosive strength, abdominal muscle endurance and flexibility) in both groups. Lower endothelial function was found in the OW compared to NW (p = 0.042) at baseline. FMD increased (p < 0.001) in both groups from baseline (NW Δ4.1%; Cohen's effect size 0.64; OW Δ4.5%; Cohen's effect size 0.73) with no significant difference between the groups. In conclusion, a HIIT program even without any dietary changes can improve physical fitness and endothelial function among adolescents. These findings are clinically relevant because they support a reduction in endothelial damage that precedes the development of atherosclerosis.

18F-Fluoride Signal Amplification Identifies Microcalcifications Associated With Atherosclerotic Plaque Instability in Positron Emission Tomography/Computed Tomography Images

BACKGROUND

Microcalcifications in atherosclerotic plaques are destabilizing, predict adverse cardiovascular events, and are associated with increased morbidity and mortality.¹⁸F-fluoride positron emission tomography (PET)/computed tomography (CT) imaging has demonstrated promise as a useful clinical diagnostic tool in identifying high-risk plaques; however, there is confusion as to the underlying mechanism of signal amplification seen in PET-positive, CT-negative image regions. This study tested the hypothesis that ¹⁸F-fluoride PET/CT can identify early microcalcifications.

METHODS

¹⁸F-fluoride signal amplification derived from microcalcifications was validated against near-infrared fluorescence molecular imaging and histology using an in vitro 3-dimensional hydrogel collagen platform, ex vivo human specimens, and a mouse model of atherosclerosis.

RESULTS

Microcalcification size correlated inversely with collagen concentration. The ¹⁸F-fluoride ligand bound to microcalcifications formed by calcifying vascular smooth muscle cell derived extracellular vesicles in the in vitro 3-dimensional collagen system and exhibited an increasing signal with an increase in collagen concentration (0.25 mg/mL collagen -33.8×10²±12.4×10² counts per minute; 0.5 mg/mL collagen -67.7×10²±37.4×10² counts per minute; P=0.0014), suggesting amplification of the PET signal by smaller microcalcifications. We further incubated human atherosclerotic endarterectomy specimens with clinically relevant concentrations of ¹⁸F-fluoride. The ¹⁸F-fluoride ligand labeled microcalcifications in PET-positive, CT-negative regions of explanted human specimens as evidenced by ¹⁸F-fluoride PET/CT imaging, near-infrared fluorescence, and histological analysis. Additionally, the ¹⁸F-fluoride ligand identified micro and macrocalcifications in atherosclerotic aortas obtained from low-density lipoprotein receptor-deficient mice.

CONCLUSIONS

Our results suggest that ¹⁸F-fluoride PET signal in PET-positive, CT-negative regions of human atherosclerotic plaques is the result of developing microcalcifications, and high surface area in regions of small microcalcifications may amplify PET signal.

Development of anti-chloro 192 tyrosine HDL apoA-I antibodies for the immunodiagnosis of cardiovascular diseases

High density lipoproteins (HDL) are considered cardio protective. Apolipoprotein A-I (apoA-I), a major component of HDL helps in reverse cholesterol transport, whose function is greatly affected during atherosclerosis due to oxidation by myeloperoxidase. Amino acid tyrosine residue of apoA-I at position 192 and 166 are sensitive to oxidation by myeloperoxidase resulting in the generation of chlorinated and nitrated apoA-I and they are believed to be present in atherosclerotic plaques and in circulation. These oxidized apoA-I have been suggested as potential indicator(s) of CVD risks in humans. To detect the levels of oxidized apoA-I there is a need for developing monoclonal antibodies (mAbs) with high specificity and sensitivity that could be utilized routinely in clinical immune based assays for blood plasma or for in vivo imaging. In this study, chemically chlorinated apoA-I (chlorinated ¹⁹²tyrosine- apoA-I) and a short synthetic peptide, containing the corresponding chlorinated tyrosine residue, conjugated to keyhole limpet hemocyanin (KLH) carrier protein were used for immunization. Stable hybridoma clones F7D5 and G11E3 were found to be highly sensitive and reactive towards chlorinated ¹⁹²tyrosine- apoA-I. Interestingly, these mAbs also displayed positive reaction with atherosclerotic plaques obtained from mouse and human biopsies. In vitro or in vivo diagnostic tests could be developed either by detecting oxidized apoA-I in human plasma or by directly imaging atheroma plaques as both mAbs were shown to stain human atheroma. The anti-chlorinated ¹⁹²tyrosine- apoA-I mAbs described in this study may have a high diagnostic potential in predicting CVD risks.

Atheroprotective Mechanisms of Tilianin by Inhibiting Inflammation Through Down-Regulating NF-κB Pathway and Foam Cells Formation

Tilianin, a representative flavonoid ingredient of Dracocephalum moldavica L., has been used to treat several diseases for centuries, including atherosclerosis (AS). However, pharmacological mechanisms underlying its biological functions remain elusive. In the present study, we investigated the anti-AS mechanisms of tilianin through establishing in vitro models using three types of cells that contributed to AS progression, including macrophage, vascular smooth muscle cells and human umbilical vein endothelial cells, which were proved to be involve in LPS/TNF-α/oxidized low density lipoprotein (ox-LDL)-induced inflammation and ox-LDL induced foam cell formation. Our results indicate that tilianin significantly suppressed LPS induced inflammatory responses on macrophage and remarkably inhibited TNF-α induced VSMCs proliferation and migration. Furthermore, the anti-inflammatory effect of tilianin on macrophages and VSMCs was proved to be mainly by downregulating TNF-α/NF-κB pathway. Moreover, our results demonstrate that tilianin significantly ameliorated ox-LDL induced macrophages oriented foam cells formation through repressing mRNA expression of SR-A1 and inducting the expression of genes related to cholesterol efflux including SRB-1 and ABCA1. However, tilianin had no effect on ox-LDL induced HUVECs injury.

Anti-atherogenic effects of CD36-targeted epigallocatechin gallate-loaded nanoparticles

Intimal macrophages play a critical role in atherosclerotic lesion initiation and progression by taking up oxidized low-density lipoprotein (oxLDL) and promoting inflammatory process. 1-(Palmitoyl)-2-(5-keto-6-octene-dioyl) phosphatidylcholine (KOdiA-PC), a major type of oxidized phosphatidylcholines (PC) found on oxLDL, has a high binding affinity to the macrophage scavenger receptor CD36 and participates in CD36-mediated recognition and uptake of oxLDL by intimal macrophages. We successfully synthesized epigallocatechin gallate (EGCG)-loaded nanoparticles (Enano), which were composed of EGCG, PC, (+) alpha-tocopherol acetate, and surfactant. We also incorporated KOdiA-PC on the surface of Enano to make ligand-coated Enano (L-Enano) to target intimal macrophages. The objectives of this study were to determine the anti-atherogenic effects of Enano and L-Enano in LDL receptor null (LDLr-/-) mice. Our in vitro data demonstrated that L-Enano had a higher binding affinity to mouse peritoneal macrophages than Enano. This high binding affinity was diminished by CD36 antibodies or knockdown of the CD36 receptor in mouse peritoneal macrophages, confirming the specific binding of L-Enano to the macrophage CD36 receptor. LDLr-/- mice were randomly divided to six groups and received weekly tail vein injection with PBS, EGCG, void nanoparticles (Vnano), Enano, ligand-coated Vnano (L-Vnano), or L-Enano once per week for 22 weeks. The dose of EGCG was 25 mg per kg body weight. L-Enano at 20 μg/mL significantly decreased production of monocyte chemoattractant protein-1, tumor necrosis factor alpha, and interleukin-6 from mouse macrophages, while having no effect on their plasma levels compared to the PBS control. There were no significant differences in blood lipid profiles among six treatment groups. Mice treated with L-Enano also had significantly smaller lesion surface areas on aortic arches compared to the PBS control. Liver EGCG content was decreased by treatments in the order of EGCG>Enano>L-Enano. Native EGCG had inhibitory effects on liver and body fat accumulation. This molecular target approach signals an important step towards inhibiting atherosclerosis development via targeted delivery of bioactive compounds to intimal macrophages.

Scaffold-based lung tumor culture on porous PLGA microparticle substrates

Scaffold-based cancer cell culture techniques have been gaining prominence especially in the last two decades. These techniques can potentially overcome some of the limitations of current three-dimensional cell culture methods, such as uneven cell distribution, inadequate nutrient diffusion, and uncontrollable size of cell aggregates. Porous scaffolds can provide a convenient support for cell attachment, proliferation and migration, and also allows diffusion of oxygen, nutrients and waste. In this paper, a comparative study was done on porous poly (lactic-co-glycolic acid) (PLGA) microparticles prepared using three porogens—gelatin, sodium bicarbonate (SBC) or novel poly N-isopropylacrylamide [PNIPAAm] particles, as substrates for lung cancer cell culture. These fibronectin-coated, stable particles (19–42 μm) supported A549 cell attachment at an optimal cell seeding density of 250,000 cells/ mg of particles. PLGA-SBC porous particles had comparatively larger, more interconnected pores, and favored greater cell proliferation up to 9 days than their counterparts. This indicates that pore diameters and interconnectivity have direct implications on scaffold-based cell culture compared to substrates with minimally interconnected pores (PLGA-gelatin) or pores of uniform sizes (PLGA-PMPs). Therefore, PLGA-SBC-based tumor models were chosen for preliminary drug screening studies. The greater drug resistance observed in the lung cancer cells grown on porous particles compared to conventional cell monolayers agrees with previous literature, and indicates that the PLGA-SBC porous microparticle substrates are promising for in vitro tumor or tissue development.

Automatic Coronary Wall and Atherosclerotic Plaque Segmentation from 3D Coronary CT Angiography

Coronary plaque burden measured by coronary computerized tomography angiography (CCTA), independent of stenosis, is a significant independent predictor of coronary heart disease (CHD) events and mortality. Hence, it is essential to develop comprehensive CCTA plaque quantification beyond existing subjective plaque volume or stenosis scoring methods. The purpose of this study is to develop a framework for automated 3D segmentation of CCTA vessel wall and quantification of atherosclerotic plaque, independent of the amount of stenosis, along with overcoming challenges caused by poor contrast, motion artifacts, severe stenosis, and degradation of image quality. Vesselness, region growing, and two sequential level sets are employed for segmenting the inner and outer wall to prevent artifact-defective segmentation. Lumen and vessel boundaries are joined to create the coronary wall. Curved multiplanar reformation is used to straighten the segmented lumen and wall using lumen centerline. In-vivo evaluation included CCTA stenotic and non-stenotic plaques from 41 asymptomatic subjects with 122 plaques of different characteristics against the individual and consensus of expert readers. Results demonstrate that the framework segmentation performed robustly by providing a reliable working platform for accelerated, objective, and reproducible atherosclerotic plaque characterization beyond subjective assessment of stenosis; can be potentially applicable for monitoring response to therapy.

Bioengineered H-Ferritin Nanocages for Quantitative Imaging of Vulnerable Plaques in Atherosclerosis

Inflammation and calcification concomitantly drive atherosclerotic plaque progression and rupture and are the compelling targets for identifying plaque vulnerability. However, current imaging modalities for vulnerable atherosclerotic plaques are often limited by inadequate specificity and sensitivity. Here, we show that natural H-ferritin nanocages radiolabeled with technetium-99m (^99mTc-HFn) can identify and accurately localize macrophage-rich, atherosclerotic plaques in living mice using combined SPECT and CT. Focal ^99mTc-HFn uptake was observed in the atherosclerotic plaques with multiple high-risk features of macrophage infiltration, active calcification, positive remodeling, and necrosis on histology and in early active ongoing lesions with intense macrophage infiltration. The uptake of ^99mTc-HFn in plaques enabled quantitative measuring of the dynamic changes of inflammation during plaque progression and anti-inflammation treatment. This strategy lays the foundation of using bioengineered endogenous human ferritin nanocages for the identification of vulnerable and early active plaques as well as potential assessment of anti-inflammation therapy.

A Snake Venom-Secreted Phospholipase A2 Induces Foam Cell Formation Depending on the Activation of Factors Involved in Lipid Homeostasis

MT-III, a snake venom GIIA sPLA₂, which shares structural and functional features with mammalian GIIA sPLA₂s, activates macrophage defense functions including lipid droplet (LDs) formation, organelle involved in both lipid metabolism and inflammatory processes. Macrophages (MΦs) loaded with LDs, termed foam cells, characterize early blood vessel fatty-streak lesions during atherosclerosis. However, the factors involved in foam cell formation induced by a GIIA sPLA₂ are still unknown. Here, we investigated the participation of lipid homeostasis-related factors in LD formation induced by MT-III in macrophages. We found that MT-III activated PPAR-γ and PPAR-β/δ and increased the protein levels of both transcription factors and CD36 in macrophages. Pharmacological interventions evidenced that PPAR-γ, PPAR-β/δ, and CD36 as well as the endoplasmic reticulum enzymes ACAT and DGAT are essential for LD formation. Moreover, PPAR-β/δ, but not PPAR-γ, is involved in MT-III-induced PLIN2 protein expression, and both PPAR-β/δ and PPAR-γ upregulated CD36 protein expression, which contributes to MT-III-induced COX-2 expression. Furthermore, production of 15-d-PGJ₂, an activator of PPARs, induced by MT-III, was dependent on COX-1 being LDs an important platform for generation of this mediator.

A review of molecular imaging of atherosclerosis and the potential application of dendrimer in imaging of plaque

Despite the fact that technological advancements have been made in diagnosis and treatment, cardiovascular diseases (CVDs) remain the leading cause of mortality and morbidity worldwide. Early detection of atherosclerosis (AS), especially vulnerable plaques, plays a crucial role in the prevention of acute coronary syndrome (ACS). Targeting the critical cytokines and molecules that are upregulated during the biological process of AS by in vivo molecular imaging has been widely used in plaque imaging. With their three-dimensional architecture, composition, and abundant terminal functional groups, dendrimers provide a platform for multitargeting and multimodal imaging. Thus, modified dendrimers with the key molecules upregulated in AS plaques will be an innovative attempt to achieve targeted imaging of AS plaques specifically and efficiently. This review was aimed to address some recent works on imaging of AS plaques using various types of image technology and further discuss the applications of dendrimers, an innovative yet seldom used method in imaging of AS plaques due to some limitations and challenges, and we highlight the bright future of the modified dendrimers in characterizing AS plaques.

Nanomedicines for dysfunctional macrophage-associated diseases

Macrophages play vital functions in host inflammatory reaction, tissue repair, homeostasis and immunity. Dysfunctional macrophages have significant pathophysiological impacts on diseases such as cancer, inflammatory diseases (rheumatoid arthritis and inflammatory bowel disease), metabolic diseases (atherosclerosis, diabetes and obesity) and major infections like human immunodeficiency virus infection. In view of this common etiology in these diseases, targeting the recruitment, activation and regulation of dysfunctional macrophages represents a promising therapeutic strategy. With the advancement of nanotechnology, development of nanomedicines to efficiently target dysfunctional macrophages can strengthen the effectiveness of therapeutics and improve clinical outcomes. This review discusses the specific roles of dysfunctional macrophages in various diseases and summarizes the latest advances in nanomedicine-based therapeutics and theranostics for treating diseases associated with dysfunctional macrophages.

In Vivo Targeting and Imaging of Atherosclerosis Using Multifunctional Virus-Like Particles of Simian Virus 40

Atherosclerosis is a leading cause of death globally. Targeted imaging and therapeutics are desirable for the detection and treatment of the disease. In this study, we developed trifunctional Simian virus 40 (SV40)-based nanoparticles for in vivo targeting and imaging of atherosclerotic plaques. These novel trifunctional SV40-based nanoparticles encapsulate near-infrared quantum dots and bear a targeting element and a drug component. Using trifunctional SV40-based nanoparticles, we were able to noninvasively fluorescently image atherosclerotic plaques in live intact ApoE(-/-) mice. Near-infrared quantum dots encapsulated in the SV40 virus-like particles showed prominent optical properties for in vivo imaging. When different targeting peptides for vascular cell adhesion molecule-1, macrophages, and fibrin were used, early, developmental, and late stages of atherosclerosis could be targeted and imaged in live intact ApoE(-/-) mice, respectively. Targeted SV40 virus-like particles also delivered an increased concentration of the anticoagulant drug Hirulog to atherosclerosis plaques. Our study provides novel SV40-based nanoparticles with multivalency and multifunctionality suitable for in vivo imaging, molecular targeting, and drug delivery in atherosclerosis.

Fluorescent probes sensitive to changes in the cholesterol-to-phospholipids molar ratio in human platelet membranes during atherosclerosis

Environment-sensitive fluorescent probes were used for the spectroscopic visualization of pathological changes in human platelet membranes during cerebral atherosclerosis. It has been estimated that the ratiometric probes 2-(2'-hydroxyphenyl)-5-phenyl-1,3,4-oxadiazole and 2-phenyl-phenanthr[9,10]oxazole can detect changes in the cholesterol-to-phospholipids molar ratio in human platelet membranes during the disease.

Recent Advances of Radionuclide-Based Molecular Imaging of Atherosclerosis

Atherosclerosis is a systemic disease characterized by the development of multifocal plaque lesions within vessel walls and extending into the vascular lumen. The disease takes decades to develop symptomatic lesions, affording opportunities for accurate detection of plaque progression, analysis of risk factors responsible for clinical events, and planning personalized treatment. Of the available molecular imaging modalities, radionuclidebased imaging strategies have been favored due to their sensitivity, quantitative detection and pathways for translational research. This review summarizes recent advances of radiolabeled small molecules, peptides, antibodies and nanoparticles for atherosclerotic plaque imaging during disease progression.

Leukocytes Link Local and Systemic Inflammation in Ischemic Cardiovascular Disease: An Expanded "Cardiovascular Continuum"

Physicians have traditionally viewed ischemic heart disease in a cardiocentric manner: plaques grow in arteries until they block blood flow, causing acute coronary and other ischemic syndromes. Recent research provides new insight into the integrative biology of inflammation as it contributes to ischemic cardiovascular disease. These results have revealed hitherto unsuspected inflammatory signaling networks at work in these disorders that link the brain, autonomic nervous system, bone marrow, and spleen to the atherosclerotic plaque and to the infarcting myocardium. A burgeoning clinical published data indicates that such inflammatory networks-far from a mere laboratory curiosity-operate in our patients and can influence aspects of ischemic cardiovascular disease that determine decisively clinical outcomes. These new findings enlarge the circle of the traditional "cardiovascular continuum" beyond the heart and vessels to include the nervous system, the spleen, and the bone marrow.

PET/MRI of Hypoxic Atherosclerosis Using 64Cu-ATSM in a Rabbit Model

The macrophage-rich core of advanced human atheroma has been demonstrated to be hypoxic, which may have implications in plaque stability. The goal of this study was to determine the feasibility of the hypoxia PET imaging agent ⁶⁴Cu-ATSM to detect hypoxia in a rabbit model of atherosclerosis imaged on a simultaneous PET/MR scanner, using MR for both attenuation correction and depiction of lesion location.

METHODS

New Zealand White rabbits fed a Western diet for 4-6 wk underwent endothelial denudation of the right femoral artery by air desiccation to induce an atherosclerotic-like lesion and underwent a sham operation on the left femoral artery. Four and 8 wk after injury, a 0- to 60-min dynamic whole-body PET/MR examination was performed after injection of approximately 111 MBq of ⁶⁴Cu-ATSM. After 24 h, a 0- to 75-min dynamic PET/MR examination after injection of approximately 111 MBq of ¹⁸F-FDG was performed. The rabbits were euthanized, and the injured femoral artery (IF) and sham-operated femoral artery (SF) were collected for immunohistochemistry assessment of hypoxic macrophages (hypoxia marker pimonidazole, macrophage marker RAM-11, and hypoxia-inducible factor-1 α subunit [HIF-1α]). Regions of interest of IF, SF, and background muscle (BM) were drawn on fused PET/MR images, and IF-to-BM and SF-to-BM SUV ratios were compared using the Student t test.

RESULTS

Elevated uptake of ⁶⁴Cu-ATSM was found in the rabbits' IF compared with the SF. ⁶⁴Cu-ATSM imaging demonstrated IF-to-SF SUV_mean ratios (±SD) of 1.75 ± 0.21 and 2.30 ± 0.26 at 4 and 8 wk after injury, respectively. ¹⁸F-FDG imaging demonstrated IF-to-SF SUV_mean ratios of 1.84 ± 0.12 at 8 wk after injury. IF-to-BM SUV_mean ratios were significantly higher (P < 0.001) than SF-to-BM SUV_mean ratios both 4 and 8 wk after injury for ⁶⁴Cu-ATSM and 8 wk after injury for ¹⁸F-FDG (P < 0.05). Pimonidazole immunohistochemistry at 8 wk colocalized to RAM-11 and HIF-1α.

CONCLUSION

The results show that hypoxia is present in this rabbit model of atherosclerosis and suggest that ⁶⁴Cu-ATSM PET/MR is a potentially promising method for the detection of hypoxic and potentially vulnerable atherosclerotic plaque in human subjects.

Endothelial Cell Dysfunction and the Pathobiology of Atherosclerosis

Dysfunction of the endothelial lining of lesion-prone areas of the arterial vasculature is an important contributor to the pathobiology of atherosclerotic cardiovascular disease. Endothelial cell dysfunction, in its broadest sense, encompasses a constellation of various nonadaptive alterations in functional phenotype, which have important implications for the regulation of hemostasis and thrombosis, local vascular tone and redox balance, and the orchestration of acute and chronic inflammatory reactions within the arterial wall. In this review, we trace the evolution of the concept of endothelial cell dysfunction, focusing on recent insights into the cellular and molecular mechanisms that underlie its pivotal roles in atherosclerotic lesion initiation and progression; explore its relationship to classic, as well as more recently defined, clinical risk factors for atherosclerotic cardiovascular disease; consider current approaches to the clinical assessment of endothelial cell dysfunction; and outline some promising new directions for its early detection and treatment.

(Second) Harmonic Disharmony: Nonlinear Microscopy Shines New Light on the Pathology of Atherosclerosis

There has been increasing interest in second harmonic generation (SHG) imaging approaches for the investigation of atherosclerosis due to the deep penetration and three-dimensional sectioning capabilities of the nonlinear optical microscope. Atherosclerosis involves remodeling or alteration of the collagenous framework in affected vessels. The disease is often characterized by excessive collagen deposition and altered collagen organization. SHG has the capability to accurately characterize collagen structure, which is an essential component in understanding atherosclerotic lesion development and progression. As a structure-based imaging modality, SHG is most impactful in atherosclerosis evaluation in conjunction with other, chemically specific nonlinear optics (NLO) techniques to identify additional components of the lesion. These include the use of coherent anti-Stokes Raman scattering and two-photon excitation fluorescence for studying atherosclerosis burden, and application of stimulated Raman scattering to image cholesterol crystals. However, very few NLO studies have attempted to quantitate differences in control versus atherosclerotic states or to correlate the application to clinical situations. This review highlights the potential of SHG imaging to directly and indirectly describe atherosclerosis as a pathological condition.

Detection and treatment of atherosclerosis using nanoparticles

Atherosclerosis is the key pathogenesis of cardiovascular disease, which is a silent killer and a leading cause of death in the United States. Atherosclerosis starts with the adhesion of inflammatory monocytes on the activated endothelial cells in response to inflammatory stimuli. These monocytes can further migrate into the intimal layer of the blood vessel where they differentiate into macrophages, which take up oxidized low-density lipoproteins and release inflammatory factors to amplify the local inflammatory response. After accumulation of cholesterol, the lipid-laden macrophages are transformed into foam cells, the hallmark of the early stage of atherosclerosis. Foam cells can die from apoptosis or necrosis, and the intracellular lipid is deposed in the artery wall forming lesions. The angiogenesis for nurturing cells is enhanced during lesion development. Proteases released from macrophages, foam cells, and other cells degrade the fibrous cap of the lesion, resulting in rupture of the lesion and subsequent thrombus formation. Thrombi can block blood circulation, which represents a major cause of acute heart events and stroke. There are generally no symptoms in the early stages of atherosclerosis. Current detection techniques cannot easily, safely, and effectively detect the lesions in the early stages, nor can they characterize the lesion features such as the vulnerability. While the available therapeutic modalities cannot target specific molecules, cells, and processes in the lesions, nanoparticles appear to have a promising potential in improving atherosclerosis detection and treatment via targeting the intimal macrophages, foam cells, endothelial cells, angiogenesis, proteolysis, apoptosis, and thrombosis. Indeed, many nanoparticles have been developed in improving blood lipid profile and decreasing inflammatory response for enhancing therapeutic efficacy of drugs and decreasing their side effects. WIREs Nanomed Nanobiotechnol 2017, 9:e1412. doi: 10.1002/wnan.1412 For further resources related to this article, please visit the WIREs website.

Aqueous or lipid components of atherosclerotic lesion increase macrophage oxidation and lipid accumulation

INTRODUCTION AND OBJECTIVE

Understanding the interactions among atherosclerotic plaque components and arterial macrophages, is essential for elucidating the mechanisms involved in the development of atherosclerosis. We assessed the effects of lesion extracts on macrophages.

METHODS

Mouse peritoneal macrophages from atherosclerotic normoglycemic or hyperglycemic apoE(-/-) mice were incubated with aortic aqueous or with aortic lipidic extracts (mAAE or mALE) derived from these mice. In parallel, J774A.1 cultured macrophages were incubated with increasing concentrations of extracts prepared from human carotid lesions: polar lesion aqueous extract (hLAE), nonpolar lesion lipid extract (hLLE), or with their combination. In all the above systems we performed analyses of macrophage oxidative status, cholesterol, and triglyceride metabolism.

RESULTS

Aqueous or lipid extracts from either mice aorta or from human carotid lesions significantly increased macrophage oxidative stress as determined by reactive oxygen species (ROS) analysis. In parallel, a compensatory increase in the cellular antioxidant paraoxonase2 (PON2) activity and in macrophage glutathione content were observed following incubation with all extracts. Macrophage triglyceride mass and triglyceride biosynthesis rate were both significantly increased following treatment with the lipid extracts, secondary to upregulation of DGAT1. All extracts decreased cholesterol biosynthesis rate, through downregulation of HMGCR, the rate limiting enzyme in cholesterol biosynthesis. The combination of the human lesion extracts had the most significant effects.

CONCLUSION

The present study demonstrates that atherosclerotic plaque constituents enhance macrophage cellular oxidative stress, and accumulation of cholesterol and triglycerides, as shown in both in vivo and in vitro model systems.

Preclinical models of atherosclerosis. The future of Hybrid PET/MR technology for the early detection of vulnerable plaque

Cardiovascular diseases are the leading cause of death in developed countries. The aetiology is currently multifactorial, thus making them very difficult to prevent. Preclinical models of atherothrombotic diseases, including vulnerable plaque-associated complications, are now providing significant insights into pathologies like atherosclerosis, and in combination with the most recent advances in new non-invasive imaging technologies, they have become essential tools to evaluate new therapeutic strategies, with which can forecast and prevent plaque rupture. Positron emission tomography (PET)/computed tomography imaging is currently used for plaque visualisation in clinical and pre-clinical cardiovascular research, albeit with significant limitations. However, the combination of PET and magnetic resonance imaging (MRI) technologies is still the best option available today, as combined PET/MRI scans provide simultaneous data acquisition together with high quality anatomical information, sensitivity and lower radiation exposure for the patient. The coming years may represent a new era for the implementation of PET/MRI in clinical practice, but first, clinically efficient attenuation correction algorithms and research towards multimodal reagents and safety issues should be validated at the preclinical level.

Formulation, characteristics and antiatherogenic bioactivities of CD36-targeted epigallocatechin gallate (EGCG)-loaded nanoparticles

Intimal macrophages are determinant cells for atherosclerotic lesion formation by releasing inflammatory factors and taking up oxidized low-density lipoprotein (oxLDL) via scavenger receptors, primarily the CD36 receptor. (-)-Epigallocatechin-3-gallate (EGCG) has a potential to decrease cholesterol accumulation and inflammatory responses in macrophages. We made EGCG-loaded nanoparticles (Enano) using phosphatidylcholine, kolliphor HS15, alpha-tocopherol acetate and EGCG. 1-(Palmitoyl)-2-(5-keto-6-octene-dioyl) phosphatidylcholine (KOdiA-PC), a CD36-targeted ligand found on oxLDL, was incorporated on the surface of Enano to make ligand-Enano (L-Enano). The objectives of this study are to deliver EGCG to macrophages via CD36-targeted L-Enano and to determine its antiatherogenic bioactivities. The optimized nanoparticles obtained in our study were spherical and around 108 nm in diameter, and had about 10% of EGCG loading capacity and 96% of EGCG encapsulation efficiency. Compared to Enano, CD36-targeted L-Enano had significantly higher binding affinity to and uptake by macrophages at the same pattern as oxLDL. CD36-targeted L-Enano dramatically improved EGCG stability, increased macrophage EGCG content, delivered EGCG to macrophage cytosol and avoided lysosomes. L-Enano significantly decreased macrophage mRNA levels and protein secretion of monocyte chemoattractant protein 1, but did not significantly change macrophage cholesterol content. The innovative CD36-targeted nanoparticles may facilitate targeted delivery of diagnostic, preventive and therapeutic compounds to intimal macrophages for the diagnosis, prevention and treatment of atherosclerosis with enhanced efficacy and decreased side effects.

High-speed intravascular photoacoustic imaging at 1.7 μm with a KTP-based OPO

Lipid deposition inside the arterial wall is a hallmark of plaque vulnerability. Based on overtone absorption of C-H bonds, intravascular photoacoustic (IVPA) catheter is a promising technology for quantifying the amount of lipid and its spatial distribution inside the arterial wall. Thus far, the clinical translation of IVPA technology is limited by its slow imaging speed due to lack of a high-pulse-energy high-repetition-rate laser source for lipid-specific first overtone excitation at 1.7 μm. Here, we demonstrate a potassium titanyl phosphate (KTP)-based optical parametric oscillator with output pulse energy up to 2 mJ at a wavelength of 1724 nm and with a repetition rate of 500 Hz. Using this laser and a ring-shape transducer, IVPA imaging at speed of 1 frame per sec was demonstrated. Performance of the IVPA imaging system's resolution, sensitivity, and specificity were characterized by carbon fiber and a lipid-mimicking phantom. The clinical utility of this technology was further evaluated ex vivo in an excised atherosclerotic human femoral artery with comparison to histology.

Detection of atherosclerotic lesions and intimal macrophages using CD36-targeted nanovesicles

Current approaches to the diagnosis and therapy of atherosclerosis cannot target lesion-determinant cells in the artery wall. Intimal macrophage infiltration promotes atherosclerotic lesion development by facilitating the accumulation of oxidized low-density lipoproteins (oxLDL) and increasing inflammatory responses. The presence of these cells is positively associated with lesion progression, severity and destabilization. Hence, they are an important diagnostic and therapeutic target. The objective of this study was to noninvasively assess the distribution and accumulation of intimal macrophages using CD36-targeted nanovesicles. Soy phosphatidylcholine was used to synthesize liposome-like nanovesicles. 1-(Palmitoyl)-2-(5-keto-6-octene-dioyl) phosphatidylcholine was incorporated on their surface to target the CD36 receptor. All in vitro data demonstrate that these targeted nanovesicles had a high binding affinity for the oxLDL binding site of the CD36 receptor and participated in CD36-mediated recognition and uptake of nanovesicles by macrophages. Intravenous administration into LDL receptor null mice of targeted compared to non-targeted nanovesicles resulted in higher uptake in aortic lesions. The nanovesicles co-localized with macrophages and their CD36 receptors in aortic lesions. This molecular target approach may facilitate the in vivo noninvasive imaging of atherosclerotic lesions in terms of intimal macrophage accumulation and distribution and disclose lesion features related to inflammation and possibly vulnerability thereby facilitate early lesion detection and targeted delivery of therapeutic compounds to intimal macrophages.

Dexamethasone-induced insulin resistance: kinetic modeling using novel PET radiopharmaceutical 6-deoxy-6-[(18)F]fluoro-D-glucose

PURPOSE

An insulin-resistant rat model, induced by dexamethasone, was used to evaluate a Michaelis-Menten-based kinetic model using 6-deoxy-6-[(18)F]fluoro-D-glucose (6-[(18)F]FDG) to quantify glucose transport with PET.

PROCEDURES

Seventeen, male, Sprague-Dawley rats were studied in three groups: control (Ctrl), control + insulin (Ctrl + I), and dexamethasone + insulin (Dex + I). PET scans were acquired for 2 h under euglycemic conditions in the Ctrl group and under hyperinsulinemic-euglycemic conditions in the Ctrl + I and Dex + I groups.

RESULTS

Glucose transport, assessed according to the 6-[(18)F]FDG concentration, was highest in skeletal muscle in the Ctrl + I, intermediate in the Dex + I, and lowest in the Ctrl group, while that in the brain was similar among the groups. Modeling analysis applied to the skeletal muscle uptake curves yielded values of parameters related to glucose transport that were greatest in the Ctrl + I group and increased to a lesser degree in the Dex + I group, compared to the Ctrl group.

CONCLUSION

6-[(18)F]FDG and the Michaelis-Menten-based model can be used to measure insulin-stimulated glucose transport under basal and an insulin resistant state in vivo.

SPECT/CT Imaging of High-Risk Atherosclerotic Plaques using Integrin-Binding RGD Dimer Peptides

Vulnerable atherosclerotic plaques with unique biological signatures are responsible for most major cardiovascular events including acute myocardial infarction and stroke. However, current clinical diagnostic approaches for atherosclerosis focus on anatomical measurements such as the degree of luminal stenosis and wall thickness. An abundance of neovessels with elevated expression of integrin αvβ3 is closely associated with an increased risk of plaque rupture. Herein we evaluated the potential of an αvβ3 integrin-targeting radiotracer, (99m)Tc-IDA-D-[c(RGDfK)]2, for SPECT/CT imaging of high-risk plaque in murine atherosclerosis models. In vivo uptake of (99m)Tc-IDA-D-[c(RGDfK)]2 was significantly higher in atherosclerotic aortas than in relatively normal aortas. Comparison with the negative-control peptide, (99m)Tc-IDA-D-[c(RADfK)]2, proved specific binding of (99m)Tc-IDA-D-[c(RGDfK)]2 for plaque lesions in in vivo SPECT/CT and ex vivo autoradiographic imaging. Histopathological characterization revealed that a prominent SPECT signal of (99m)Tc-IDA-D-[c(RGDfK)]2 corresponded to the presence of high-risk plaques with a large necrotic core, a thin fibrous cap, and vibrant neoangiogenic events. Notably, the RGD dimer based (99m)Tc-IDA-D-[c(RGDfK)]2 showed better imaging performance in comparison with the common monomeric RGD peptide probe (123)I-c(RGDyV) and fluorescence tissue assay corroborated this. Our preclinical data demonstrated that (99m)Tc-IDA-D-[c(RGDfK)]2 SPECT/CT is a sensitive tool to noninvasively gauge atherosclerosis beyond vascular anatomy by assessing culprit plaque neovascularization.

Nanomedicine for the molecular diagnosis of cardiovascular pathologies

Predicting acute clinical events caused by atherosclerotic plaque rupture remains a clinical challenge. Anatomic mapping of the vascular tree provided by standard imaging technologies is not always sufficient for a robust diagnosis. Yet biological mechanisms leading to unstable plaques have been identified and corresponding biomarkers have been described. Nanosystems charged with contrast agents and targeted towards these specific biomarkers have been developed for several types of imaging modalities. The first systems that have reached the clinic are ultrasmall superparamagnetic iron oxides for Magnetic Resonance Imaging. Their potential relies on their passive accumulation by predominant physiological mechanisms in rupture-prone plaques. Active targeting strategies are under development to improve their specificity and set up other types of nanoplatforms. Preclinical results show a huge potential of nanomedicine for cardiovascular diagnosis, as long as the safety of these nanosystems in the body is studied in depth.

The mechanism by which moderate alcohol consumption influences coronary heart disease

Background

Moderate alcohol consumption is associated with a lower risk for coronary heart disease (CHD). A suitably integrated view of the CHD pathogenesis pathway will help to elucidate how moderate alcohol consumption could reduce CHD risk.

Methods

A comprehensive literature review was conducted focusing on the pathogenesis of CHD. Biomarker data were further systematically analysed from 294 cohort studies, comprising 1 161 560 subjects. From the above a suitably integrated CHD pathogenetic system for the purpose of this study was developed.

Results

The resulting integrated system now provides insight into the integrated higher-order interactions underlying CHD and moderate alcohol consumption. A novel ‘connection graph’ further simplifies these interactions by illustrating the relationship between moderate alcohol consumption and the relative risks (RR) attributed to various measureable CHD serological biomarkers. Thus, the possible reasons for the reduced RR for CHD with moderate alcohol consumption become clear at a glance.

Conclusions

An integrated high-level model of CHD, its pathogenesis, biomarkers, and moderate alcohol consumption provides a summary of the evidence that a causal relationship between CHD risk and moderate alcohol consumption may exist. It also shows the importance of each CHD pathway that moderate alcohol consumption influences.

How do high glycemic load diets influence coronary heart disease?

Background

Diet has a significant relationship with the risk of coronary heart disease (CHD). Traditionally the effect of diet on CHD was measured with the biomarker for low-density lipoprotein (LDL) cholesterol. However, LDL is not the only or even the most important biomarker for CHD risk. A suitably integrated view of the mechanism by which diet influences the detailed CHD pathogenetic pathways is therefore needed in order to better understand CHD risk factors and help with better holistic CHD prevention and treatment decisions.

Methods

A systematic review of the existing literature was conducted. From this an integrated CHD pathogenetic pathway system was constructed. CHD biomarkers, which are found on these pathways, are the only measurable data to link diet with these CHD pathways. They were thus used to simplify the link between diet and the CHD mechanism. Data were systematically analysed from 294 cohort studies of CHD biomarkers constituting 1 187 350 patients.

Results and discussion

The resulting integrated analysis provides insight into the higher-order interactions underlying CHD and high-glycemic load (HGL) diets. A novel “connection graph” illustrates the measurable relationship between HGL diets and the relative risks attributed to the important CHD serological biomarkers.

The “connection graph” vividly shows that HGL diets not only influence the lipid and metabolic biomarkers, but also the inflammation, coagulation and vascular function biomarkers in an important way.

Conclusion

A focus primarily on the low density lipoprotein cholesterol biomarker for CHD risk has led to the traditional guidelines of CHD dietary recommendations. This has however inadvertently led to HGL diets. The influence of HGL diets on the other CHD biomarkers is not always fully appreciated. Thus, new diets or other interventions which address the full integrated CHD impact, as shown in this paper, are required.

Structure and biomedical applications of amyloid oligomer nanoparticles

Amyloid oligomers are nonfibrillar polypeptide aggregates linked to diseases, such as Alzheimer's and Parkinson's. Here we show that these aggregates possess a compact, quasi-crystalline architecture that presents significant nanoscale regularity. The amyloid oligomers are dynamic assemblies and are able to release their individual subunits. The small oligomeric size and spheroid shape confer diffusible characteristics, electrophoretic mobility, and the ability to enter hydrated gel matrices or cells. We finally showed that the amyloid oligomers can be labeled with both fluorescence agents and iron oxide nanoparticles and can target macrophage cells. Oligomer amyloids may provide a new biological nanomaterial for improved targeting, drug release, and medical imaging.

High-speed intravascular photoacoustic imaging of lipid-laden atherosclerotic plaque enabled by a 2-kHz barium nitrite raman laser

Lipid deposition inside the arterial wall is a key indicator of plaque vulnerability. An intravascular photoacoustic (IVPA) catheter is considered a promising device for quantifying the amount of lipid inside the arterial wall. Thus far, IVPA systems suffered from slow imaging speed (~50 s per frame) due to the lack of a suitable laser source for high-speed excitation of molecular overtone vibrations. Here, we report an improvement in IVPA imaging speed by two orders of magnitude, to 1.0 s per frame, enabled by a custom-built, 2-kHz master oscillator power amplifier (MOPA)-pumped, barium nitrite [Ba(NO3)2] Raman laser. This advancement narrows the gap in translating the IVPA technology to the clinical setting.

99mTc-cAbVCAM1-5 imaging is a sensitive and reproducible tool for the detection of inflamed atherosclerotic lesions in mice

(99m)Tc-cAbVCAM1-5, a single-domain antibody fragment directed against mouse or human vascular cell adhesion molecule 1 (VCAM-1), recently has been proposed as a new imaging agent for the detection of inflamed atherosclerotic lesions. Indeed, in a mouse model of atherosclerosis, (99m)Tc-cAbVCAM1-5 specifically bound to VCAM-1-positive lesions, thereby allowing their identification on SPECT images. The purpose of the present study was to investigate (99m)Tc-cAbVCAM1-5 imaging sensitivity using a reference statin therapy.

METHODS

Thirty apolipoprotein E-deficient mice were fed a western-type diet. First, the relationship between the level of VCAM-1 expression and (99m)Tc-cAbVCAM1-5 uptake was evaluated in 18 mice using immunohistochemistry and autoradiography. Second, longitudinal SPECT/CT imaging was performed on control (n = 9) or atorvastatin-treated mice (0.01% w/w, n = 9).

RESULTS

(99m)Tc-cAbVCAM1-5 uptake in atherosclerotic lesions correlated with the level of VCAM-1 expression (P < 0.05). Atorvastatin exerted significant antiatherogenic effects, and (99m)Tc-cAbVCAM1-5 lesion uptake was significantly reduced in 35-wk-old atorvastatin-treated mice, as indicated by ex vivo γ-well counting and autoradiography (P < 0.05). SPECT imaging quantification based on contrast-enhanced CT was reproducible (interexperimenter intraclass correlation coefficient, 0.97; intraexperimenter intraclass correlation coefficient, 0.90), and yielded results that were highly correlated with tracer biodistribution (r = 0.83; P < 0.0001). Therefore, reduced (99m)Tc-cAbVCAM1-5 uptake in atorvastatin-treated mice was successfully monitored noninvasively by SPECT/CT imaging (0.87 ± 0.06 vs. 1.11 ± 0.09 percentage injected dose per cubic centimeter in control group, P < 0.05).

CONCLUSION

(99m)Tc-cAbVCAM1-5 imaging allowed the specific, sensitive, and reproducible quantification of VCAM-1 expression in mouse atherosclerotic lesions. (99m)Tc-cAbVCAM1-5 therefore exhibits suitable characteristics for the evaluation of novel antiatherogenic agents.

Microwave-assisted synthesis of surface-enhanced Raman scattering nanoprobes for cellular sensing

The fabrication of 4-mercaptobenzoic acid (4-MBA) antibody-functionalized gold nanoparticles via microwave technology for surface-enhanced Raman scattering (SERS)-based cellular nanosensing is reported. Nanoprobes were characterized by UV-vis absorbance, Raman scattering properties, and observed by TEM imaging. Results showed that microwave irradiation rapidly yielded nanoprobes with significant Raman scattering intensity and suitable stability to support antibody conjugation in under 10min. Functionalized nanoprobes demonstrated the ability to map the expression of vascular adhesion molecule-1 (VCAM-1) in human coronary artery endothelial (HCAE) cells, indicating that microwave fabrication presents a viable and rapid approach to SERS nanoprobe construction. The successful application of SERS nanoprobes to localize biomarker expression in vitro may ultimately be used for early diagnostic and preventative functions in medicine.

Pepsin-pancreatin protein hydrolysates from extruded amaranth inhibit markers of atherosclerosis in LPS-induced THP-1 macrophages-like human cells by reducing expression of proteins in LOX-1 signaling pathway

BACKGROUND

Atherosclerosis is considered a progressive disease that affects arteries that bring blood to the heart, to the brain and to the lower end. It derives from endothelial dysfunction and inflammation, which play an important role in the thrombotic complications of atherosclerosis. Cardiovascular disease is the leading cause of death around the world and one factor that can contribute to its progression and prevention is diet. Our previous study found that amaranth hydrolysates inhibited LPS-induced inflammation in human and mouse macrophages by preventing activation of NF-κB signaling. Furthermore, extrusion improved the anti-inflammatory effect of amaranth protein hydrolysates in both cell lines, probably attributed to the production of bioactive peptides during processing. Therefore, the objective of this study was to compare the anti-atherosclerotic potential of pepsin-pancreatin hydrolysates from unprocessed and extruded amaranth in THP-1 lipopolysaccharide-induced human macrophages and suggest the mechanism of action.

RESULTS

Unprocessed amaranth hydrolysate (UAH) and extruded amaranth hydrolysate (EAH) showed a significant reduction in the expression of interleukin-4 (IL-4) (69% and 100%, respectively), interleukin-6 (IL-6) (64% and 52%, respectively), interleukin-22 (IL-22) (55% and 70%, respectively). Likewise, UAH and EAH showed a reduction in the expression of monocyte-chemo attractant protein-1 (MCP-1) (35% and 42%, respectively), transferrin receptor-1 (TfR-1) (48% and 61%, respectively), granulocyte-macrophage colony-stimulating factor (GM-CSF) (59% and 63%, respectively), and tumor necrosis factor-α (TNF-α) (60% and 63%, respectively). Also, EAH reduced the expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) (27%), intracellular adhesion molecule-1 (ICAM-1) (28%) and matrix metalloproteinase-9 (MMP-9) (19%), important molecular markers in the atherosclerosis pathway. EAH, led to a reduction of 58, 52 and 79% for LOX-1, ICAM-1 and MMP-9, respectively, by confocal microscopy.

CONCLUSIONS

Extruded amaranth hydrolysate showed potential anti-atherosclerotic effect in LPS-induced THP-1 human macrophage-like cells by reducing the expression of proteins associated with LOX-1 signaling pathway.

Connexin43 siRNA promotes HUVEC proliferation and inhibits apoptosis induced by ox-LDL: an involvement of ERK signaling pathway

Oxidized low-density lipoprotein (ox-LDL), one of the most important risk factors of atherosclerosis, is a highly antigenic, potent chemoattractant that facilitates the development of atherosclerosis. Gap junctions also play an important in the development of atherosclerosis. In this study, we investigated the effects of ox-LDL on connexin43 and the mechanisms of connexin43 siRNA-inhibited apoptosis induced by ox-LDL in human umbilical vein endothelial cell (HUVEC), to clarify the role of connexin43 in atherosclerosis. Our results showed that ox-LDL significantly inhibited the growth and promoted apoptosis of HUVEC in a dose-dependent manner. Also, ox-LDL upregulated the expression of connexin43. Furthermore, knockdown connexin43 by siRNA promoted proliferation and inhibited apoptosis in ox-LDL-stimulated HUVEC. Moreover, the level of phosphor-ERK1/2 and connexin43 was remarkably attenuated by a ERK pathway inhibitor (PD98059). These results suggest that connexin43 siRNA promotes HUVEC proliferation and inhibits apoptosis induced by ox-LDL, and ERK signaling pathway appears to be involved in these processes.