Plasma Lipidomics and Coronary Plaque Changes: A Substudy of the SMARTool Clinical Trial

AIMS

To date, no studies have investigated the association between lipid species and coronary plaque changes over time, quantitatively assessed by serial imaging. We aimed to prospectively determine the association between lipid species quantified by plasma lipidomic analysis, with coronary plaque changes according to composition assessed by quantitative serial analysis of coronary computed tomography angiography (CTA).

METHODS AND RESULTS

Patients with suspected coronary artery disease (CAD) undergoing baseline coronary CTA were prospectively enrolled by 7 EU Centers in the SMARTool study and submitted to clinical, molecular and coronary CTA re-evaluation at follow-up (interscan period 6.39 ± 1.17 years). From the 202 patients that were analysed in the SMARTool main clinical study, lipidomic analysis was performed in 154 patients before the baseline coronary CTA, and this group was included in the present study. Quantitative CTA analysis was performed by a separate core laboratory blinded from clinical data. In univariable analysis, no lipid species were significantly associated with annual total and calcified plaque changes. After adjusting for clinical variables at baseline and statin use, 3 lipid species were significantly associated with non-calcified plaque progression. In detail, cholesteryl ester (CE)(20:3), sphingomyelin (SM)(40:3) and SM(41:1) were found positively related to non-calcified plaque progression (Bonferroni adjusted P-value = 0.005, 0.016 and 0.004, respectively).

CONCLUSION

The current study showed an independent relationship between specific lipid species determined by plasma lipidomic analysis, and non-calcified coronary plaque progression assessed by serial, quantitative coronary CTA analysis.

Proteomic Modulation in TGF-β-Treated Cholangiocytes Induced by Curcumin Nanoparticles

Curcumin is a natural polyphenol that exhibits a variety of beneficial effects on health, including anti-inflammatory, antioxidant, and hepato-protective properties. Due to its poor water solubility and membrane permeability, in the present study, we prepared and characterized a water-stable, freely dispersible nanoformulation of curcumin. Although the potential of curcumin nanoformulations in the hepatic field has been studied, there are no investigations on their effect in fibrotic pathological conditions involving cholangiocytes. Exploiting an in vitro model of transforming growth factor-β (TGF-β)-stimulated cholangiocytes, we applied the Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS)-based quantitative proteomic approaches to study the proteome modulation induced by curcumin nanoformulation. Our results confirmed the well-documented anti-inflammatory properties of this nutraceutic, highlighting the induction of programmed cell death as a mechanism to counteract the cellular damages induced by TGF-β. Moreover, curcumin nanoformulation positively influenced the expression of several proteins involved in TGF-β-mediated fibrosis. Given the crucial importance of deregulated cholangiocyte functions during cholangiopathies, our results provide the basis for a better understanding of the mechanisms associated with this pathology and could represent a rationale for the development of more targeted therapies.

Apolipoprotein E ε4 triggers neurotoxicity via cholesterol accumulation, acetylcholine dyshomeostasis, and PKCε mislocalization in cholinergic neuronal cells

The Apolipoprotein E (ApoE) has been known to regulate cholesterol and β-amyloid (Aβ) production, redistribution, and elimination, in the central nervous system (CNS). The ApoE ε4 polymorphic variant leads to impaired brain cholesterol homeostasis and amyloidogenic pathway, thus representing the major risk factor for Alzheimer's Disease (AD). Currently, less is known about the molecular mechanisms connecting ApoE ε4-related cholesterol metabolism and cholinergic system degeneration, one of the main AD pathological features. Herein, in vitro cholinergic neuron models were developed in order to study ApoE neuronal expression and investigate the possible interplay between cholesterol metabolism and cholinergic pathway impairment prompted by ε4 isoform. Particularly, alterations specifically occurring in ApoE ε4-carrying neurons (i.e. increased intracellular ApoE, amyloid precursor protein (APP), and Aβ levels, elevated apoptosis, and reduced cell survival) were recapitulated. ApoE ε4 expression was found to increase intracellular cholesterol accumulation, by regulating the related gene expression, while reducing cholesterol precursor acetyl-CoA, which in turn fuels the acetylcholine (ACh) synthesis route. In parallel, although the ACh intracellular signalling was activated, as demonstrated by the boosted extracellular ACh as well as increased IP₃ and Ca²⁺, the PKCε activation via membrane translocation was surprisingly suppressed, probably explained by the cholesterol overload in ApoE ε4 neuron-like cells. Consequently, the PKC-dependent anti-apoptotic and neuroprotective roles results impaired, reliably adding to other causes of cell death prompted by ApoE ε4. Overall, the obtained data open the way to further critical considerations of ApoE ε4-dependent cholesterol metabolism dysregulation in the alteration of cholinergic pathway, neurotoxicity, and neuronal death.

Transcriptional level evaluation of osteopontin/miRNA-181a axis in hepatocellular carcinoma cell line-secreted extracellular vesicles

Recent evidence suggested the role of secreted extracellular vesicles (EVs) in the intracellular signalling within the liver becoming a promising candidate as biomarker in hepatocellular carcinoma (HCC). Osteopontin (OPN) seems to play a relevant role both for early diagnosis of HCC than on the mechanisms that drive oncogenesis but, to date, information on the expression levels of OPN in EVs secreted by HCC tumor cell line are missing. The study aimed to verify, by transcriptional and proteomic study, the presence of OPN in EVs secreted by tumorigenic (HepG2) and non-tumorigenic hepatocyte cell line (WRL68), and to analyse the expression variations of OPN, its isoforms and miRNA-181a in both these EVs. "In silico analysis" was also performed via the Gene expression Profiling Interactive analysis (GEPIA) and Hepatocellular Carcinoma Database (HCCDB). An up-regulation of OPN in EVs secreted by HepG2 with respect to WRL68 was found in line with the results obtained by the "in silico analysis". The study demonstrates, for the first time, the OPN isoforms and its modulator miRNA-181a expression in EVs secreted by both cell lines, highlighting high levels of OPN isoforms in EVs secreted by HepG2 and identifying OPN as a promising biomarker for HCC diagnosis.

Association of MMP9 with adverse features of plaque progression and residual inflammatory risk in patients with chronic coronary syndrome (CCS)

BACKGROUND AND AIMS

MMP-9 is a predictor of atherosclerotic plaque instability and adverse cardiovascular events, but longitudinal data on the association between MMP9 and coronary disease progression are lacking. This study is aimed at investigating whether MMP9 is associated with atherosclerotic plaque progression and the related molecular basis in stable patients with chronic coronary syndrome (CCS).

METHODS

MMP9 serum levels were measured in 157 CCS patients (58 ± 8 years of age; 66% male) undergoing coronary computed tomography angiography at baseline and after a follow up period of 6.5 ± 1.1 years to assess progression of Total, Fibrous, Fibro-fatty, Necrotic Core, and Dense Calcium plaque volumes (PV). Gene expression analysis was evaluated in whole blood using a transcriptomic approach by RNA-seq.

RESULTS

At multivariate analysis, serum MMP9 was associated with annual change of Total and Necrotic Core PV (Coefficient 3.205, SE 1.321, P = 0.017; 1.449, SE 0.690, P = 0.038, respectively), while MMP9 gene expression with Necrotic Core PV (Coefficient 70.559, SE 32.629, P = 0.034), independently from traditional cardiovascular risk factors, medications, and presence of obstructive CAD. After transcriptomic analysis, MMP9 expression was linked to expression of genes involved in the innate immunity.

CONCLUSIONS

Among CCS patients, MMP9 is an independent predictive marker of progression of adverse coronary plaques, possibly reflecting the activity of inflammatory pathways conditioning adverse plaque phenotypes. Thus, blood MMP9 might be used for the identification of patients with residual risk even with optimal management of classical cardiovascular risk factors who may derive the greatest benefit from targeted anti-inflammatory drugs.

Predictive Added Value of Selected Plasma Lipids to a Re-estimated Minimal Risk Tool

Background: Lipidomics is emerging for biomarker discovery in cardiovascular disease, and circulating lipids are increasingly incorporated in risk models to predict cardiovascular events. Moreover, specific classes of lipids, such as sphingomyelins, ceramides, and triglycerides, have been related to coronary artery disease (CAD) severity and plaque characteristics. To avoid unnecessary testing, it is important to identify individuals at low CAD risk. The only pretest model available so far to rule out the presence of coronary atherosclerosis in patients with chest pain, but normal coronary arteries, is the minimal risk tool (MRT).

Aim: Using state-of-the-art statistical methods, we aim to verify the additive predictive value of a set of lipids, derived from targeted plasma lipidomics of suspected CAD patients, to a re-estimated version of the MRT for ruling out the presence of coronary atherosclerosis assessed by coronary CT angiography (CCTA).

Methods: Two hundred and fifty-six subjects with suspected stable CAD recruited from five European countries within H2020-SMARTool, undergoing CCTA and blood sampling for clinical biochemistry and lipidomics, were selected. The MRT was validated by regression methods and then re-estimated (reMRT). The reMRT was used as a baseline model in a likelihood ratio test approach to assess the added predictive value of each lipid from 13 among ceramides, triglycerides, and sphingomyelins. Except for one lipid, the analysis was carried out on more than 240 subjects for each lipid. A sensitivity analysis was carried out by considering two alternative models developed on the cohort as baseline models.

Results: In 205 subjects, coronary atherosclerosis ranged from minimal lesions to overt obstructive CAD, while in 51 subjects (19.9%) the coronary arteries were intact. Four triglycerides and seven sphingomyelins were significantly (p < 0.05) and differentially expressed in the two groups and, at a lesser extent, one ceramide (p = 0.067). The probability of being at minimal risk was significantly better estimated by adding either Cer(d18:1/16:0) (p = 0.01), SM(40:2) (p = 0.04), or SM(41:1) at a lesser extent (p = 0.052) to reMRT than by applying the reMRT alone. The sensitivity analysis confirmed the relevance of these lipids. Furthermore, the addition of SM(34:1), SM(38:2), SM(41:2), and SM(42:4) improved the predictive performance of at least one of the other baseline models. None of the selected triglycerides was found to provide an added value.

Conclusions: Plasma lipidomics can be a promising source of diagnostic and prognostic biomarkers in cardiovascular disease, exploitable not only to assess the risk of adverse events but also to identify subjects without coronary atherosclerosis, thus reducing unnecessary further testing in normal subjects.

Lipid biomarkers in statin users with coronary artery disease annotated by coronary computed tomography angiography

Molecular markers are suggested to improve the diagnostic and prognostic accuracy in patients with coronary artery disease (CAD) beyond current clinical scores based on age, gender, symptoms and traditional risk factors. In this context, plasma lipids are emerging as predictors of both plaque composition and risk of future events. We aim to identify plasma lipid biomarkers associated to CAD indexes of stenosis severity, plaque lipid content and a comprensive score of CAD extent and its risk. We used a simple high performance liquid chromatography-tandem mass spectrometry method to identify 69 plasma lipids in 132 subjects referred to Coronary Computed Tomography Angiography (CCTA) for suspected CAD, all under statin treatment. Patients were stratified in groups using three different CCTA-based annotations: CTA-risk score, lipid plaque prevalence (LPP) ratio and the coronary artery disease-reporting and data system (CAD-RADS). We identified a common set of lipid biomarkers composed of 7 sphingomyelins and 3 phosphatidylethanolamines, which discriminates between high risk CAD patients and controls regardless of the CAD annotations used (CTA score, LPP ratio, or CAD-RADS). These results highlight the potential of circulating lipids as biomarkers of stenosis severity, non calcified plaque composition and overall plaque risk of events.