Increased circulating monocyte count is related to good collateral development in coronary artery disease

Preserved myocardial viability in patients with chronic total occlusion of a single coronary artery

OBJECTIVE

To assess the benefits of coronary collateral circulation on myocardial perfusion, viability and function in patients with total occlusion of a single coronary artery using the 99mTc-sestamibi SPECT and 18F-fluorodeoxyglucose PET.

METHODS

164 Consecutive patients were included who underwent coronary angiography results exhibited total occlusion of a single coronary artery and received 99mTc-MIBI SPECT and 18F-FDG PET within 90 days of angiography. Myocardial perfusion and viability in patients with collateral circulation and those without it were compared. Long-term follow-up was performed through a review of patient clinical records.

RESULTS

Collateral circulation was present in 56 patients (34%) and absent in 108 patients (66%). The total perfusion defect size in patients with collateral circulation decreased when compared to those without (30% ± 13% to 35% ± 14%, P < .05). The myocardial viability was 22% ± 12% in patients with collateral circulation, and 12% ± 9% in those without (P < .001). The left ventricular ejection fraction was higher, and the end-diastolic and end-systolic left ventricular volumes were lower in patients with collateral circulation (39% ± 11%, 138 ± 66, 89 ± 57) compared to patients without collateral circulation (31% ± 9%, 177 ± 55, 125 ± 48, all P < .001, respectively). Multi-factor logistic regression identified that concerning the variables of sex, age, viable myocardium, collateral circulation, treatment type and others, only treatment type was significantly associated with therapeutic effects (OR 3.872, 95% CI 1.915-7.830, P < .001).

CONCLUSION

Collateral circulation can preserve resting myocardial blood perfusion and myocardial viability, and help maintain the function of the left ventricular myocardium. The appropriate treatment strategy will have a substantial impact on the therapeutic outcome.

Predictive value of SPECT myocardial perfusion imaging in patients with unrevascularized coronary chronic total occlusion

OBJECTIVE

Data involved the association between myocardial ischaemia and the outcome for unrevascularized coronary chronic total occlusion (CTO) patients were limited. The purpose of this study was to evaluate the predictive value of ischaemia detected by single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) for the adverse events in unrevascularized CTO patients. We further explored whether ischaemia generated from CTO vessel can independently predict the outcome.

METHODS

Patients with at least one unrevascularized CTO on coronary angiography were enrolled in this study. Exercise stress/rest SPECT MPI was performed in all patients. All patients were then followed by telephone interview and reviewing of medical records.

RESULTS

Patients with ischaemia experienced significantly higher rate of adverse events than non-ischaemia patients (40.7% vs 7.1%, P = 0.002). Ischaemia demonstrated on MPI [odds ratio (OR) = 7.656; 95% confidence interval (CI) 1.598-36.677; P = 0.011] was an independent predictor for adverse events. Moreover, CTO-ischaemia (OR = 5.466; 95% CI 1.015-29.420; P = 0.048), non-CTO ischaemia (OR = 29.174; 95% CI 3.245-262.322; P = 0.003), mixed-ischaemia (OR = 7.130, 95% CI 1.257-40.445; P = 0.027) were all independent predictors for outcome.

CONCLUSION

Ischaemia demonstrated on MPI, especially CTO-ischaemia were independent predictors for the adverse events. SPECT MPI can aid to identify patients at risk of adverse events, who may benefit from subsequent CTO percutaneous coronary intervention.

Genetic variants of VEGFR-1 gene promoter in acute myocardial infarction

BACKGROUND

Coronary artery disease (CAD) including acute myocardial infarction (AMI) is a common complex disease caused by atherosclerosis. Vascular epithelial growth factor receptor-1 (VEGFR-1) stimulates angiogenesis and vascular permeability, and functions as a decoy to sequester VEGF and prevent initiation of intracellular signaling. VEGFR-1 knockout mice exhibit significantly higher mortality due to heart failure, cardiac hypertrophy, and cardiac dysfunction. An evident increase in macrophage infiltration and cardiac fibrosis are also observed after transverse aortic constriction. Therefore, VEGFR-1 gene variants may be involved in CAD. In this study, VEGFR-1 gene promoter was genetically and functionally analyzed in large cohorts of AMI patients and ethnic-matched controls.

RESULTS

A total of 16 DNA sequence variants (DSVs) including six single-nucleotide polymorphisms (SNPs) were found in the VEGFR-1 gene promoter and 5'-untranslated region. Five novel DSVs and one SNP were only identified in AMI patients group. These DSVs and SNP significantly altered the transcriptional activity of the VEGFR-1 gene promoter in both HEK-293 and H9c2 cells (P < 0.05). Further electrophoretic mobility shift assay indicated that the DSVs and SNPs evidently affected the binding of transcription factors.

CONCLUSIONS

The genetic variants in VEGFR-1 gene identified in AMI patients may alter the transcriptional activity of the VEGFR-1 gene promoter and change VEGFR-1 level, contributing to AMI development.

Plasma Omentin-1 Level as a Predictor of Good Coronary Collateral Circulation

Aims: Coronary collateral circulation (CCC) is crucial during an acute ischemic attack. Evidences showed that omentin-1 exhibited remarkable antiatherogenic effects and ischemia-induced revascularization. The aim of this study was to investigate the relationship between plasma omentin-1 levels and CCC in patients with ≥ 90% angiography-proven coronary occlusion.

Methods: 142 patients with ≥ 90% luminal diameter stenosis in at least one major epicardial coronary artery were recruited. Among them, 79 patients with Rentrop 0–1 grade were classified into the poor CCC group and 63 patients with Rentrop 2–3 grade were included into the good CCC group. The association between plasma omentin-1 levels and CCC status was assessed.

Results: Plasma omentin-1 level was significantly higher in patients with good CCC than those with poor CCC (566.57 ± 26.90 vs. 492.38 ± 19.70 ng/mL, p = 0.024). Besides, omentin-1 was positively correlated with total cholesterol (TC), high-density lipoprotein, and gensini score but inversely with hyperlipidemia and body mass index (all p values < 0.05). Multivariate regression analysis indicated that omentin-1 [odds ratio (OR) = 1.002, 95% confidence interval (CI): 1.000 – 1.004, p = 0.041)], TC, the number of the diseased vessels, a higher frequency of left circumflex artery and right coronary artery, chronic total occlusion, and gensini score remained as the independent predictors of good CCC.

Conclusion: Higher plasma omentin-1 level was associated with better CCC development. Our findings suggest that omentin-1 may be an alternative marker for adequate CCC in patients with ≥ 90% coronary occlusion.

Mutually Supportive Mechanisms of Inflammation and Vascular Remodeling

Chronic inflammation is often accompanied by angiogenesis, the development of new blood vessels from existing ones. This vascular response is a response to chronic hypoxia and/or ischemia, but is also contributory to the progression of disorders including atherosclerosis, arthritis, and tumor growth. Proinflammatory and proangiogenic mediators and signaling pathways form a complex and interrelated network in these conditions, and many factors exert multiple effects. Inflammation drives angiogenesis by direct and indirect mechanisms, promoting endothelial proliferation, migration, and vessel sprouting, but also by mediating extracellular matrix remodeling and release of sequestered growth factors, and recruitment of proangiogenic leukocyte subsets. The role of inflammation in promoting angiogenesis is well documented, but by facilitating greater infiltration of leukocytes and plasma proteins into inflamed tissues, angiogenesis can also propagate chronic inflammation. This review examines the mutually supportive relationship between angiogenesis and inflammation, and considers how these interactions might be exploited to promote resolution of chronic inflammatory or angiogenic disorders.

The Peripheral Blood Mononuclear Cell Count Is Associated With Bone Health in Elderly Men: A Cross-Sectional Population-Based Study

The peripheral blood mononuclear cell (PBMC) count is a routinely used and meaningful index for infection and blood diseases. PBMCs may be closely related to osteoclasts and include osteoclast precursors; we examined the association between the PBMC count and bone health. This research included 2806 community men aged ≥50 years who underwent full health examinations from October 2007 through December 2011 in four medical centers. The PBMC count was significantly high among subjects with "at least osteopenia" compared with controls. In analysis of covariance adjusted for potential confounders, the bone mineral density (BMD) value and T-score had a significant decreasing trend across the quartiles of PBMC count. In univariate analysis, the PBMC count had a strong association with "at least osteopenia" (odds ratio [OR] = 2.520, 95% confidence interval [CI]: 1.397-4.547). After adjustment for confounding factors (multivariate analysis) from Model 1 to 4, PBMC count remained as an independent risk factor for "at least osteopenia" (OR = 2.481, 95% CI: 1.176-5.236). Moreover, after adjusting for all confounding variables, participants had a significantly high OR in the body mass index (BMI) <25 group (OR = 2.798, CI: 1.122-6.973; P = 0.027) and systolic blood pressure (SBP) <140 group (OR = 2.519, CI: 1.059-5.993; P = 0.037). In conclusion, the PBMC count is significantly associated with bone loss in elderly men and the exact mechanism requires further clarification.

Circulating MicroRNAs Characterizing Patients with Insufficient Coronary Collateral Artery Function

BACKGROUND

Coronary collateral arteries function as natural bypasses in the event of coronary obstruction. The degree of collateral network development significantly impacts the outcome of patients after an acute myocardial infarction (AMI). MicroRNAs (miRNAs, miRs) have arisen as biomarkers to identify heterogeneous patients, as well as new therapeutic targets in cardiovascular disease. We sought to identify miRNAs that are differentially expressed in chronic total occlusion (CTO) patients with well or poorly developed collateral arteries.

METHODS AND RESULTS

Forty-one CTO patients undergoing coronary angiography and invasive assessment of their coronary collateralization were dichotomized based on their collateral flow index (CFI). After miRNA profiling was conducted on aortic plasma, four miRNAs were selected for validation by real-time quantitative reverse transcription polymerase chain reaction in patients with low (CFI<0.39) and high (CFI>0.39) collateral artery capacity. We confirmed significantly elevated levels of miR423-5p (p<0.05), miR10b (p<0.05), miR30d (p<0.05) and miR126 (p<0.001) in patients with insufficient collateral network development. We further demonstrated that each of these miRNAs could serve as circulating biomarkers to discriminate patients with low collateral capacity (p<0.01 for each miRNA). We also determined significantly greater expression of miR30d (p<0.05) and miR126 (p<0.001) in CTO patients relative to healthy controls.

CONCLUSION

The present study identifies differentially expressed miRNAs in patients with high versus low coronary collateral capacity. We have shown that these miRNAs can function as circulating biomarkers to discriminate between patients with insufficient or sufficient collateralization. This is the first study to identify miRNAs linked to coronary collateral vessel function in humans.

The future of collateral artery research

In the event of obstructive coronary artery disease, collateral arteries have been deemed an alternative blood source to preserve myocardial tissue perfusion and function. Monocytes play an important role in modulating this process, by local secretion of growth factors and extracellular matrix degrading enzymes. Extensive efforts have focused on developing compounds for augmenting the growth of collateral vessels (arteriogenesis). Nonetheless, clinical trials investigating the therapeutic potential of these compounds resulted in disappointing outcomes. Previous studies focused on developing compounds that stimulated collateral vessel growth by enhancing monocyte survival and activity. The limited success of these compounds in clinical studies, led to a paradigm shift in arteriogenesis research. Recent studies have shown genetic heterogeneity between CAD patients with sufficient and insufficient collateral vessels. The genetic predispositions in patients with poorly developed collateral vessels include overexpression of arteriogenesis inhibiting signaling pathways. New directions of arteriogenesis research focus on attempting to block such inhibitory pathways to ultimately promote arteriogenesis. Methods to detect collateral vessel growth are also critical in realizing the therapeutic potential of newly developed compounds. Traditional invasive measurements of intracoronary derived collateral flow index remain the gold standard in quantifying functional capacity of collateral vessels. However, advancements made in hybrid diagnostic imaging modalities will also prove to be advantageous in detecting the effects of pro-arteriogenic compounds.

Predictors of poor coronary collateral development in patients with stable coronary artery disease: neutrophil-to-lymphocyte ratio and platelets

Objective:

The heterogeneity in the degree of collateralization among patients with coronary artery disease (CAD) remains incompletely understood. We evaluated the predictors of poorly developed coronary collateral circulation (CCC) in patients with stable coronary artery disease.

Methods:

Current study is a retrospective study, consisting of 118 patients with poor CCC and 130 patients with good CCC. We investigated predictors of poor coronary collaterals in a cohort of 248 patients who had high-grade coronary stenosis or occlusion on their angiograms. To classify CCC, we used the Rentrop classification.

Results:

Patients with poorly developed CCC had significantly higher neutrophil-to-lymphocyte ratio (N/L) compared with those with well-developed CCC, (4.2±2.8 vs. 3±3.1, p=0.001), whereas mean platelet volume, red cell distribution width and uric acid were not significantly different. Logistic regression analysis showed that N/L ratio (odds ratio 1.199, 95% confidence interval 1.045-1.375) and serum triglyceride levels [odds ratio (OR)=1.006, 95% confidence interval (CI)=1.001-1.010] were independent predictors of poorly developed CCC.

Conclusion:

An elevated level of N/L ratio is independently associated with a significant impairment in coronary collateralization. Our findings suggest that N/L ratio is an inexpensive, universally available hematological marker for sufficiency of CCC in patients with stable coronary artery disease.

The Relationship Between Neutrophil-to-Lymphocyte Ratio and Coronary Collateral Circulation

Neutrophil/lymphocyte ratio (NLR) has been proposed as a prognostic marker to determine systemic inflammatory response and atherosclerosis. Our aim was to determine the relationship between NLR and development of coronary collateral circulation (CCC) in patients with stable coronary artery disease (CAD). A total of 521 consecutive patients with stable CAD who underwent coronary angiography and documented total occlusion in one of those major coronary arteries were included in this study. Levels of fasting blood glucose, white blood cell, and NLR were significantly higher in patients with poor collateral than in those with good collateral. After multivariate analysis, high level of NLR was an independent predictor of CCC together with levels of fasting blood glucose. The receiver–operating characteristic analysis provided a cutoff value of 2.75 for NLR to predict poor CCC with 65% sensitivity and 68% specificity. We demonstrated an independent association between levels of NLR and development of CCC in patients with stable CAD.

Mechanistic, technical, and clinical perspectives in therapeutic stimulation of coronary collateral development by angiogenic growth factors

Stimulation of collateral vessel development in the heart by angiogenic growth factor therapy has been tested in animals and humans for almost two decades. Discordance between the outcome of preclinical studies and clinical trials pointed to the difficulties of translation from animal models to patients. Lessons learned in this process identified specific mechanistic, technical, and clinical hurdles, which need to be overcome. This review summarizes current understanding of the mechanisms leading to the establishment of a functional coronary collateral network and the biological processes growth factor therapies should stimulate even under conditions of impaired natural adaptive vascular response. Vector delivery methods are recommended to maximize angiogenic gene therapy efficiency and reduce side effects. Optimization of clinical trial design should include the choice of clinical end points which provide mechanistic proof-of-concept and also reflect clinical benefits (e.g., surrogates to assess increased collateral flow reserve, such as myocardial perfusion imaging). Guidelines are proposed to select patients who may respond to the therapy with high(er) probability. Both short and longer term strategies are outlined which may help to make therapeutic angiogenesis (TA) work in the future.

Arterial occlusion induces systemic changes in leucocyte composition

BACKGROUND

Lack of tissue perfusion because of arterial occlusion can result in mortality and morbidity. In response to local tissue ischaemia, extravasation of leucocytes into the region at risk is initiated to facilitate matrix remodelling and subsequent perfusion recovery. However, it is unknown if local tissue ischaemia also induces a more generalized response of leucocyte trafficking and compartmentalization. This study was designed to gain insight into the temporal changes in circulating and bone marrow-derived leucocyte fractions following peripheral arterial occlusion in mice.

MATERIALS AND METHODS

Mouse peripheral blood and bone marrow samples were collected at baseline and subsequently at day 1, 2, 3, 4 and 7 after femoral artery ligation. Leucocyte and bone marrow cell subsets were quantified using flow cytometry.

RESULTS

After arterial occlusion, peripheral blood leucocyte numbers did not vary significantly over time. However, significant intrinsic temporal changes in cell numbers were observed for monocytes, lymphocytes, neutrophils and their subsets with fluctuations of > 50%. Granulocytes, for example, showed an initial upregulation, while monocytes and lymphocytes numbers initially decreased. These variations in the circulation were largely preceded by changes in the corresponding bone marrow lineages. Progenitor cells of the myeloid and lymphoid lineage in the bone marrow were upregulated after the decrease in the numbers of their progeny in the peripheral blood.

CONCLUSIONS

Local arterial occlusion results in an orchestrated systemic response of leucocyte trafficking. This response substantiates the pivotal role of leucocytes as mediators of processes leading to perfusion recovery and tissue remodelling.

An elevated level of BNP in plasma is related to the development of good collateral circulation in coronary artery disease

Objective: B-type natriuretic peptide (BNP) was recently demonstrated to be a potential stimulator of angiogenesis and arteriogenesis. The correlation between BNP level and collateral formation in patients with coronary artery disease (CAD) has not been reported.

Methods and results: The study included 311 consecutive patients who underwent coronary angiography were divided into three groups according to coronary angiography and collateral formation: normal group (100 patients with normal coronary angiographic findings); poor collateral group (116 patients with at least one coronary stenosis of ≥75% without visible collateral circulation); and good collateral group (95 patients with at least one coronary stenosis of ≥75% with well-developed collateral circulation). Collateral score was analyzed using the Cohen–Rentrop classification. Plasma BNP levels were 45.77 ± 4.66 pg/ml, 116.40 ± 28.15 pg/ml, and 254.20 ± 42.85 pg/ml for patients in normal, poor collateral, and good collateral groups, respectively. Plasma BNP levels in the latter were significantly higher than in the normal group ( p < 0.01) and poor collateral group ( p < 0.05). There were no significant differences between the good collateral group and poor collateral group when compared with left ventricular ejection fraction (LVEF), left ventricular dimensions at end diastole (LVEDd), age, severity of angiographic disease, and other cardiovascular risk factors. After adjustment in the multiple ordinal logistic regression model, plasma BNP levels showed a strong independent association with collateral Cohen–Rentrop score (χ2 = 5.636, OR = 1.002, 95% CI 1.000–1.004, p = 0.018).

Conclusions: An elevated level of BNP in plasma is independently associated with collateral development; patients with good collaterals tend to have a higher BNP level.

Plasma hyaluronan and collateral development in patients with coronary artery disease

OBJECTIVE

In-vivo studies have shown that hyaluronan (HA) can promote angiogenesis and arteriogenesis, which results in accelerated collateral development. This study is aimed at investigating the association between plasma HA levels and the extent of coronary collaterals, in patients with coronary artery disease.

METHODS

A total of 253 consecutive patients, who underwent coronary angiography, were divided into three groups according to coronary angiograms: normal group, 81 patients with normal coronary angiographic findings; poor collateral group, 98 patients with at least one coronary stenosis of at least 75%, but without visible collateral circulation; good collateral group, 74 patients with at least one coronary stenosis of at least 75% with well-developed collateral circulation. Plasma HA levels were measured by radioimmunoassay. The correlation between HA levels and the extent of coronary collaterals according to the Cohen-Rentrop classification was calculated by cumulative logits models.

RESULTS

Plasma HA levels were 43.71+/-2.91, 61.77+/-4.10, and 131.97+/-11.76 ng/ml, for patients in the normal, poor collateral, and good collateral groups, respectively. The good collateral group had significantly higher plasma HA levels than the poor collateral (P<0.001) and normal group (P<0.001), whereas there was no significant difference between the normal and poor collateral group. HA levels elevated with increasing Rentrop score, and the cumulative logits model showed a strong graded association between plasma HA levels and the collateral Cohen-Rentrop score (odds ratio=1.021, chi2=17.811, 95% confidence interval: 1.011-1.031, P=0.000).

CONCLUSION

This study suggests that elevated plasma HA levels are associated with a significant enhancement in coronary collateralization. HA may serve as a novel potential biomarker for collateral formation in patients with coronary artery disease.

Plasma Cathepsin L and Its Related Pro/Antiangiogenic Factors Play Useful Roles in Predicting Rich Coronary Collaterals in Patients with Coronary Heart Disease

Cathepsin L enhances angiogenesis by increasing extracellular matrix degradation and remodelling. This study investigated whether plasma cathepsin L could be used as a biomarker to predict collateral formation in patients with coronary heart disease (CHD). Patients with CHD ( n = 218; aged 67 ± 11 years) underwent coronary angiography and were categorized as having either ‘poor’ or ‘rich’ collaterals. Plasma cathepsin L, the proangiogenic placenta growth factor (PLGF) and the antiangiogenic factors, cystatin C and endostatin, were measured. Elevated cathepsin L and PLGF levels were independently and significantly associated with enhanced collateral formation in patients with CHD; subgroup analyses also showed a significant correlation in patients with diabetes and acute coronary syndrome. Plasma endostatin and cystatin C levels were not significantly correlated with coronary collateral formation. Plasma cathepsin L and PLGF, acting as important modulators of angiogenesis, could be used as biomarkers to predict coronary collateral formation in patients with CHD.

The association of circulating monocyte count with coronary collateral growth in patients with diabetes mellitus

The status of inflammation may affect the collateral development in patients with diabetes mellitus (DM). Monocytes were found to have an important role in collateral growth in animal studies. We aimed to investigate the possible association of circulating monocyte count with collateral development in patients with DM and severe coronary artery disease (CAD). We enrolled 134 consecutive patients with DM who had > or =95 stenosis in at least one major coronary artery and investigated the relationship between circulating monocyte count and collateral growth. When we analyzed the coronary angiograms of eligible patients, we found that 64 of them had good collateral growth and 70 had poor collateral growth according to the Cohen-Rentrop method. The monocyte count was significantly different between good and poor collateral growth groups (643 +/- 184 vs. 479 +/- 143 per mm(3), P < 0.001). In the analysis comparing the Rentrop score with the Gensini score and circulating monocyte count, we found significant correlations (r = 0.293, P = 0.001 and r = 0.455, P < 0.001, respectively). The duration of ischemic symptoms tended to be longer in the good collateral group (1.9 +/- 4.1 vs. 0.8 +/- 1.3 years, P = 0.079). The Gensini score was also correlated with the duration of myocardial ischemic symptoms (r = 0.299, P = 0.004). Multivariate analysis revealed an increased monocyte count in the good collateral group [odds ratio (OR), 5.726; 95% confidence interval (CI), 1.817-18.040, P = 0.003, the cut-off value for monocyte was defined as 550 cell/mm(3)]. The increased circulating monocyte count in diabetic patients was evidently related to good coronary collateral growth. This finding may be potentially important in clinical and basic cardiovascular medicine.