Cholesterol Efflux and Collateral Circulation in Chronic Total Coronary Occlusion: Effect-Circ Study

SerpinG1: A Novel Biomarker Associated With Poor Coronary Collateral in Patients With Stable Coronary Disease and Chronic Total Occlusion

Background This study aimed to explore predictive biomarkers of coronary collateralization in patients with chronic total occlusion. Methods and Results By using a microarray expression profiling program downloaded from the Gene Expression Omnibus database, weighted gene coexpression network analysis was constructed to analyze the relationship between potential modules and coronary collateralization and screen out the hub genes. Then, the hub gene was identified and validated in an independent cohort of patients (including 299 patients with good arteriogenic responders and 223 patients with poor arteriogenic responders). Weighted gene coexpression network analysis showed that SERPING1 in the light-cyan module was the only gene that was highly correlated with both the gene module and the clinical traits. Serum levels of serpinG1 were significantly higher in patients with bad arteriogenic responders than in patients with good arteriogenic responders (472.53±197.16 versus 314.80±208.92 μg/mL; P<0.001) and were negatively associated with the Rentrop score (Spearman r=-0.50; P<0.001). Receiver operating characteristic curve analysis indicated that the area under the curve was 0.77 (95% CI, 0.72-0.81; P<0.001) for serum serpinG1 in prediction of bad arteriogenic responders. After adjusting for traditional cardiovascular risk factors, serum serpinG1 levels (per SD) remained an independent risk factor for bad arteriogenic responders (odds ratio, 2.20 [95% CI, 1.76-2.74]; P<0.001). Conclusions Our findings illustrate that SERPING1 screened by weighted gene coexpression network analysis was associated with poor collateralization in patients with chronic total occlusion.

Differentially hypomethylated cell-free DNA and coronary collateral circulation

BACKGROUND

The factors affecting cardioprotective collateral circulation are still incompletely understood. Recently, characteristics, such as CpG methylation of cell-free DNA (cfDNA), have been reported as markers with clinical utility. The aim of this study was to evaluate whether cfDNA methylation patterns are associated with the grade of coronary collateral circulation (CCC).

RESULT

In this case-control study, clinical and angiographic data were obtained from 143 patients (mean age, 58 years, male 71%) with chronic total coronary occlusion. Enzymatic methyl-sequencing (EM-seq) libraries were prepared using the cfDNA extracted from the plasma. Data were processed to obtain the average methylation fraction (AMF) tables of genomic regions from which blacklisted regions were removed. Unsupervised analysis of the obtained AMF values showed that some of the changes in methylation were due to CCC. Through random forest preparation process, 256 differentially methylated region (DMR) candidates showing strong association with CCC were selected. A random forest classifier was then constructed, and the area under the curve of the receiver operating characteristic curve indicated an appropriate predictive function for CCC. Finally, 20 DMRs were identified to have significantly different AMF values between the good and poor CCC groups. Particularly, the good CCC group exhibited hypomethylated DMRs. Pathway analysis revealed five pathways, including TGF-beta signaling, to be associated with good CCC.

CONCLUSION

These data have demonstrated that differential hypomethylation was identified in dozens of cfDNA regions in patients with good CCC. Our results support the clinical utility of noninvasively obtained epigenetic signatures for predicting collateral circulation in patients with vascular diseases.

Diabetic dyslipidemia impairs coronary collateral formation: An update

Coronary collateralization is substantially impaired in patients with type 2 diabetes and occlusive coronary artery disease, which leads to aggravated myocardial ischemia and a more dismal prognosis. In a diabetic setting, altered serum lipid profiles and profound glycoxidative modification of lipoprotein particles induce endothelial dysfunction, blunt endothelial progenitor cell response, and severely hamper growth and maturation of collateral vessels. The impact of dyslipidemia and lipid-lowering treatments on coronary collateral formation has become a topic of heightened interest. In this review, we summarized the association of triglyceride-based integrative indexes, hypercholesterolemia, increased Lp(a) with its glycoxidative modification, as well as quantity and quality abnormalities of high-density lipoprotein with impaired collateral formation. We also analyzed the influence of innovative lipid-modifying strategies on coronary collateral development. Therefore, clinical management of diabetic dyslipidemia should take into account of its effect on coronary collateralization in patients with occlusive coronary artery disease.

Serum CTRP9 Reflects Coronary Collateralization in Nondiabetic Patients with Obstructive Coronary Artery Disease

Aim. To explore the association between the serum C1q/tumor necrosis factor-related protein 9 (CTRP9) and the formation of coronary collateral circulation in obstructive coronary artery disease (CAD). Methods. A total of 206 patients who underwent coronary angiography at Beijing Anzhen Hospital and had epicardial arteries with at least 95% stenotic lesion were enrolled. Blood samples were taken after an overnight fasting before the coronary angiography. Serum CTRP9 level was measured using commercial enzyme linked immunosorbent assay (ELISA) kit. The development of coronary collateralization was determined according to the Rentrop classification system. Rentrop score 0-1 was graded as impaired or less-developed coronary collateralization ( $n=54$ ) while the Rentrop score 2-3 was defined as well-developed collateralization ( $n=152$ ). Results. Serum CTRP9 level was significantly higher in well-developed collateralization and diabetes groups ( $P<0.001$ ). To further explore the association between the CTRP9 level and coronary collateralization, the enrolled participants were divided into 3 tertiles according to the serum CTRP9 level. The prevalence of impaired coronary collateralization decreased stepwise with the increasing CTRP9 tertiles ( $P$ for trend <0.001). Multivariate regression analysis showed that the serum CTRP9 is independently associated with well-developed collateralization, with an OR (95% CI) of 4.49 (1.75-11.55) and 8.98 (2.75-29.35) in the tertiles 2 and 3, respectively. The following subgroup and receiver-operating characteristic (ROC) analysis also indicated that the diagnostic value of serum CTRP9 level for detecting the formation of collateralization persisted only in nondiabetic participants. Lastly, adding the serum CTRP9 into the baseline model could increase the diagnostic value of established model consisting of relevant factor for the discrimination of well-developed collateralization only in the nondiabetic group ( $P=0.046$ ). Conclusions. Serum CTRP9 reflects well-developed coronary collateralization in nondiabetic patients with obstructive CAD, and $\text{CTRP}9\text{level}\ge 1.217$ indicated a greater chance to forming well-developed coronary collaterals.

Lipids and Lipoproteins in Health and Disease: Focus on Targeting Atherosclerosis

Despite advances in pharmacotherapy, intervention devices and techniques, residual cardiovascular risks still cause a large burden on public health. Whilst most guidelines encourage achieving target levels of specific lipids and lipoproteins to reduce these risks, increasing evidence has shown that molecular modification of these lipoproteins also has a critical impact on their atherogenicity. Modification of low-density lipoprotein (LDL) by oxidation, glycation, peroxidation, apolipoprotein C-III adhesion, and the small dense subtype largely augment its atherogenicity. Post-translational modification by oxidation, carbamylation, glycation, and imbalance of molecular components can reduce the capacity of high-density lipoprotein (HDL) for reverse cholesterol transport. Elevated levels of triglycerides (TGs), apolipoprotein C-III and lipoprotein(a), and a decreased level of apolipoprotein A-I are closely associated with atherosclerotic cardiovascular disease. Pharmacotherapies aimed at reducing TGs, lipoprotein(a), and apolipoprotein C-III, and enhancing apolipoprotein A-1 are undergoing trials, and promising preliminary results have been reported. In this review, we aim to update the evidence on modifications of major lipid and lipoprotein components, including LDL, HDL, TG, apolipoprotein, and lipoprotein(a). We also discuss examples of translating findings from basic research to potential therapeutic targets for drug development.

Cholesterol Efflux and Collateral Circulation in Chronic Total Coronary Occlusion: Effect-Circ Study

Background

The mechanism through which high‐density lipoprotein (HDL) induces cardioprotection is not completely understood. We evaluated the correlation between cholesterol efflux capacity (CEC), a functional parameter of HDL, and coronary collateral circulation (CCC). We additionally investigated whether A1BP (apoA1‐binding protein) concentration correlates with CEC and CCC.

Methods and Results

In this case‐control study, clinical and angiographic data were collected from 226 patients (mean age, 58 years; male, 72%) with chronic total coronary occlusion. CEC was assessed using a radioisotope and J774 cells, and human A1BP concentration was measured using enzyme‐linked immunosorbent assay. Differences between the good and poor CCC groups were compared, and associations between CEC, A1BP, and other variables were evaluated. Predictors of CCC were identified by multivariable logistic regression analysis. The CEC was higher in the good than in the poor CCC group (22.0±4.6% versus 20.2±4.7%; P=0.009). In multivariable analyses including age, sex, HDL‐cholesterol levels, age (odds ratio [OR], 0.96; P=0.003), and CEC (OR, 1.10; P=0.004) were identified as the independent predictors of good CCC. These relationships remained significant after additional adjustment for diabetes mellitus, acute coronary syndrome, and Gensini score. The A1BP levels were not significantly correlated with CCC (300 pg/mL and 283 pg/mL in the good CCC and poor CCC groups, respectively, P=0.25) or CEC.

Conclusions

The relationship between higher CEC and good CCC indicates that well‐functioning HDL may contribute to CCC and may be cardioprotective; this suggests that a specific function of HDL can have biological and clinical consequences.