Leukocytosis and ischemic vascular disease morbidity and mortality: is it time to intervene?

Interleukin-3/granulocyte macrophage colony-stimulating factor receptor promotes stem cell expansion, monocytosis, and atheroma macrophage burden in mice with hematopoietic ApoE deficiency

OBJECTIVE

Coronary heart disease is associated with monocytosis. Studies using animal models of monocytosis and atherosclerosis such as ApoE(-/-) mice have shown bone marrow (BM) hematopoietic stem and multipotential progenitor cell (HSPC) expansion, associated with increased cell surface expression of the common β subunit of the granulocyte macrophage colony-stimulating factor/interleukin-3 receptor (CBS) on HSPCs. ApoE(-/-) mice also display increased granulocyte macrophage colony-stimulating factor-dependent monocyte production in the spleen. We investigated the role of the CBS in cholesterol-driven HSPC expansion, monocytosis, and atherosclerosis.

APPROACH AND RESULTS

Ldlr(-/-) mice were transplanted with ApoE(-/-)Cbs(-/-) or ApoE(-/-) BM followed by Western-type diet feeding. Compared with ApoE(-/-) BM-transplanted controls, ApoE(-/-)Cbs(-/-) BM-transplanted mice had reduced BM and splenic HSPC proliferation, fewer blood monocytes and neutrophils, and reduced macrophage content and area of early atherosclerotic lesions. More advanced lesions showed diminished macrophage and collagen content; however, lesion size was unchanged, reflecting an increase in necrotic core area, associated with a marked decrease in Abcg1 expression and increased macrophage apoptosis. Compared with wild-type mice, Western-type diet-fed ApoE(-/-) mice showed increased CBS expression on granulocyte macrophage colony-stimulating factor-producing innate response activator B cells and expansion of this population. ApoE(-/-)Cbs(-/-) BM-transplanted Ldlr(-/-) mice showed a marked decrease in innate response activator B cells compared with ApoE(-/-) BM-transplanted Ldlr(-/-) controls.

CONCLUSIONS

Increased levels of CBS on HSPCs and splenic innate response activator B cells lead to expansion of these populations in ApoE(-/-) BM-transplanted Ldlr(-/-) mice, contributing to monocytosis and increased lesional macrophage content. However, in more advanced lesions, the CBS also has a role in atherosclerotic plaque stabilization.

Investigation of neutrophil lymphocyte ratio and blood glucose regulation in patients with type 2 diabetes mellitus

Objective

Leukocytosis is thought to be directly associated with the pathogenesis of atherosclerosis and metabolic syndrome. Increased white blood cell (WBC) count is related to cardiovascular disease in patients with type 2 diabetes mellitus; raised neutrophil lymphocyte ratio (NLR) is associated with metabolic syndrome. There is little information, however, concerning a correlation between glycosylated haemoglobin (HbA1c) and NLR. The aim of the present study was to investigate the relationship between NLR and blood glucose regulation.

Methods

This retrospective study was conducted in patients with type 2 diabetes mellitus, divided into two groups according to HbA1c levels: group 1, HbA1c levels ≤ 7%; group 2, HbA1c levels > 7%. Venous WBC, neutrophil and lymphocyte counts were determined.

Results

Of 71 patients included, fasting serum glucose, neutrophil and WBC counts were significantly higher in group 2 compared with group 1. NLR had a positive correlation with HbA1c.

Conclusion

There may be a significant relationship between NLR and blood glucose regulation. The authors propose that increased NLR may be associated with elevated HbA1c in patients with type 2 diabetes mellitus.

A macrophage-specific synthetic promoter for therapeutic application of adiponectin

Foam cell formation from macrophage is a major cause of atherosclerosis. An efficient macrophage-specific promoter is required for the targeting to macrophages. In this study, we develop a macrophage-specific synthetic promoter for the therapeutic application of adiponectin (APN), an antiatherogenic gene. Synthetic promoter-146 (SP146), registered on the NCBI website (http://www.ncbi.nlm.nih.gov/nuccore/DQ107383), was tested for promoter activities in two non-macrophage cell lines (293 T, HeLa) and a macrophage cell line (RAW264.7, bone marrow-derived macrophages). To enforce macrophage specificity, partial elements of p47(phox) including the PU.1 site with various lengths (-C1, -C2 and -C3) were inserted next to the synthetic promoters. SP146-C1 showed the highest specificity and efficacy in RAW264.7 cells and was selected for development of an APN-carrying macrophage-specific promoter. Green fluorescent protein (GFP)- or APN-expressing lentivirus under SP146-C1 (Lenti-SP-GFP or Lenti-SP-APN, respectively) showed the highest expression efficacy in RAW264.7 cells compared with the non-macrophage cell lines. APN overexpression in RAW264.7 cells successfully inhibited intracellular lipid accumulation, and atherosclerotic lesions and lipid accumulation were significantly reduced by Lenti-SP-APN in ApoE-/- atherosclerosis mice. In conclusion, the synthetic promoter SP146-C1, combined with a p47(phox) promoter element, was successfully developed to target macrophage, and macrophage-specific introduction of APN under SP146-C1 was shown to ameliorate the atherosclerotic pathology.

Association of total white cell count with mortality and major adverse events in patients with peripheral arterial disease: a systematic review

OBJECTIVES

Peripheral arterial disease (PAD) is principally caused by atherosclerosis, an established inflammatory disease. Total white cell count (TWCC) is a marker of inflammation and has been associated with outcomes for patients with inflammatory diseases. The aim of this systematic review was to assess the association of TWCC with mortality and major adverse events (MAEs) in PAD patients.

METHODS

Studies investigating the association of TWCC with outcome in patients with PAD were identified by a literature search using the Medline and Cochrane databases. To be eligible for inclusion, studies needed to investigate the association of TWCC with mortality or a composite endpoint that included mortality in patients with PAD. Studies were excluded when the primary focus was carotid artery disease, aortic aneurysmal disease, intracranial vascular disease, or rheumatoid arthritis and treatment with chemotherapy or transplantation of stem cells. Secondary searching of reference lists and relevant reviews was performed.

RESULTS

Ten studies including 8,490 patients with PAD met the inclusion criteria. All studies investigated more than 100 patients with four studies assessing more than 1,000 patients. Study quality varied with well-established risk factors of outcome such as age, smoking, diabetes, and the ankle brachial index being adjusted for inconsistently. The study populations were also disparate. Few studies reported relative risk and 95% confidence intervals for the association of TWCC with mortality or MAE. TWCC was positively and significantly associated with death alone in four of five studies investigating 3,387 patients. TWCC was positively and significantly associated with MAE in five of six studies investigating a total of 6,846 patients.

CONCLUSIONS

Current evidence suggests a positive association of TWCC with mortality and MAEs in patients with PAD. Further well-designed prospective studies are required with high-quality analysis and more complete reporting of outcomes.

Hypercholesterolemia-induced priming of hematopoietic stem and progenitor cells aggravates atherosclerosis

Modulation of hematopoietic stem and progenitor cells (HSPCs) determines immune cell function. In this study, we investigated how hypercholesterolemia affects HSPC biology and atherosclerosis. Hypercholesterolemia induced loss of HSPC quiescence, characterized by increased proliferation and expression of cyclin B1, C1, and D1, and a decreased expression of Rb, resulting in a 3.6- fold increase in the number of HSPCs in hypercholesterolemic Ldlr(-/-) mice. Competitive bone marrow (BM) transplantations showed that a hypercholesterolemic BM microenvironment activates HSPCs and skews their development toward myeloid lineages. Conversely, hypercholesterolemia-primed HSPCs acquired an enhanced propensity to generate myeloid cells, especially granulocytes and Ly6C(high) monocytes, even in a normocholesterolemic BM microenvironment. In conformity, macrophages differentiated from hypercholesterolemia-primed HSPCs produced 17.0% more TNF-α, 21.3% more IL-6, and 10.5% more MCP1 than did their normocholesterolemic counterparts. Hypercholesterolemia-induced priming of HSPCs generated leukocytes that more readily migrated into the artery, which resulted in a 2.1-fold increase in atherosclerotic plaque size. In addition, these plaques had a more advanced phenotype and exhibited a 1.2-fold increase in macrophages and 1.8-fold increase in granulocytes. These results identify hypercholesterolemia-induced activation and priming of HSPCs as a novel pathway in the development of atherosclerosis. Inhibition of this proinflammatory differentiation pathway on the HSPC level has the potential to reduce atherosclerosis.

Hypercholesterolemia induces oxidant stress that accelerates the ageing of hematopoietic stem cells

Background

Clinical studies suggest that hypercholesterolemia may cause ageing in hematopoietic stem cells (HSCs) because ageing‐associated alterations were found in peripheral blood cells and their bone marrow residing precursors in patients with advanced atherosclerosis. We hypothesized that hypercholesterolemia induces oxidant stress in hematopoietic stems cells that accelerates their ageing.

Methods and Results

Here we show that HSCs from ApoE^−/− mice, as well as HSCs from C57Bl/6 mice fed a high cholesterol diet (HCD) accumulated oxLDL and had greater ROS levels. In accordance, the expression pattern of the genes involved in ROS metabolism changed significantly in HSCs from ApoE^−/− mice. Hypercholesterolemia caused a significant reduction in phenotypically defined long‐term HSC compartment, telomere length, and repopulation capacity of KTLS cells, indicating accelerated ageing in these cells. Gene array analysis suggested abnormal cell cycle status, and the key cell cycle regulators including p19^ARF, p27^Kip1 and p21^Waf1 were upregulated in KTLS cells from hypercholesterolemic mice. These effects were p38‐dependent and reversed in vivo by treatment of hypercholesterolemic mice with antioxidant N‐acetylcysteine. The oxidant stress also caused aberrant expression of Notch1 that caused loss of quiescence and proliferation leading to the expansion of KTLS compartment in hypercholesterolemic mice.

Conclusion

Taken together, we provide evidence that hypercholesterolemia can cause oxidant stress that accelerates the ageing and impairs the reconstitution capacity of HSCs.

Neutrophil to Lymphocyte Ratio Predicts Perioperative Mortality Following Open Elective Repair of Abdominal Aortic Aneurysms

Objectives:

This study assesses the predictive value of neutrophil to lymphocyte ratio (NLR) in relation to 30-day and overall mortality following open abdominal aortic aneurysm (AAA) repairs. In addition, it assess assesses any correlation between NLR and age, size of the AAA and gender.

Methods:

Patients undergoing elective or urgent open repair of their AAA by a single surgeon during a 10-year period were included. A pre-operative NLR of >5 was regarded as abnormal.

Results:

350 consecutive patients underwent AAA repair. 52 had an NLR>5. 30-day mortality rate was 12/52 (23%) in the NLR>5 group and 20/298 (6.7%) in the NLR<5 group (p = 0.0007). All deaths in the NLR>5 group were due to myocardial infarction. The median NLR was higher in those that died within 30 days at 4.2 [IQR: 2.6-7.5] versus 2.8 [IQR: 2.1-3.8] (p = 0.0001). Overall mortality at 10 years, in the NLR>5 group - 26/52 (50%) was significantly greater than that of the NLR<5 group - 102/298 (34.2%) (p = 0.043). Median NLR of those dying during follow-up was significantly higher in those with a baseline NLR>5 at 3.2 (IQR 2.5-4.6) versus 2.6 (IQR: 2.0-3.6) in those surviving (p = 0.00004). No difference was found between NLR and age, aneurysm size or gender.

Conclusion:

Pre-operative NLR>5 appears to be a significant predictor of both 30-day mortality and long-term outcome in elective and urgent open AAA surgery. It is plausible the NLR is identifying a group with sub-clinical cardiovascular disease at risk of peri-operative myocardial infarction.

From proliferation to proliferation: monocyte lineage comes full circle

Monocytes are mononuclear circulating phagocytes that originate in the bone marrow and give rise to macrophages in peripheral tissue. For decades, our understanding of monocyte lineage was bound to a stepwise model that favored an inverse relationship between cellular proliferation and differentiation. Sophisticated molecular and surgical cell tracking tools have transformed our thinking about monocyte topo-ontogeny and function. Here, we discuss how recent studies focusing on progenitor proliferation and differentiation, monocyte mobilization and recruitment, and macrophage differentiation and proliferation are reshaping knowledge of monocyte lineage in steady state and disease.

Prognostic value of culprit site neutrophils in acute coronary syndrome

BACKGROUND

Recent data suggest that acute coronary syndromes (ACS) and acute myocardial infarction (AMI) are characterized by an inflammatory subset of thrombosis. We have previously described the accumulation of neutrophils at the coronary culprit lesion site. In this work, we assessed the prognostic value of culprit site (CS) neutrophil accumulation on long-term mortality in patients with AMI.

MATERIALS AND METHODS

In this prospective study, 417 AMI patients were enrolled after thrombectomy during primary percutaneous coronary intervention. The optimal cut-off for CS neutrophil accumulation for predicting 4-year all-cause mortality was calculated using time-dependent receiver operator characteristic curve analyses.

RESULTS

The median follow-up time was 39 months interquartile range (IQR 21·4-54·6 months) corresponding to 1217 patient years of follow-up. The cut-off for CS neutrophil accumulation (difference between culprit neutrophil counts and systemic neutrophil counts) was 0·25 Giga/l. CS neutrophil accumulation occurred in 195 patients (47%) and was independently associated with mortality (hazard ratio 1·88 (95%CI 1·02-3·41, P = 0·043)). In patients with CS neutrophil accumulation, 1-year mortality (10·8% vs. 7·2%) and 4-year mortality (19·8% vs. 10·4%) were markedly increased compared with patients without local neutrophil accumulation. Concordance index for CS neutrophil accumulation and mortality was 0·64 (95% CI 0·51-0·77; P = 0·035). Patients with CS neutrophil accumulation had significantly more often nonobstructive lesions compared with patients without neutrophil accumulation (32·6% vs. 22·4%; P = 0·024).

CONCLUSIONS

Neutrophil accumulation at the coronary culprit lesion site is a strong and independent predictor of mortality in patients with ACS/AMI.

Relationship between leucocytosis and left ventricular ejection fraction in patients with acute myocardial infarction

INTRODUCTION

Myocardial infarction (MI) is common and affects a significant number of people annually. Death occurs due to either arrhythmia or heart failure. As leucocytosis, especially elevated neutrophil count, is a hallmark of inflammatory reactions in patients with MI, we investigated the relationship between leucocytosis on admission and left ventricular ejection fraction (LVEF) in patients with acute MI (AMI).

METHODS

Patients with AMI were enrolled in a case-control study. Blood samples obtained in the first 24 hours after the onset of pain were analysed for cardiac enzyme levels and cell count. Echocardiography was performed on Days 3-5. Patients with LVEF < 45% were assigned to the left ventricular (LV) systolic dysfunction group (n = 69) and those with LVEF ≥ 45% were taken as controls (n = 69). All patients were matched for variables such as hypertension, diabetes mellitus, hyperlipidaemia, family history of cardiac disease, age and gender.

RESULTS

Leucocytosis was higher in patients with systolic dysfunction (47.8%) when compared with the controls (20.3%), and was significantly associated with the development of LV systolic dysfunction (p = 0.001). Similarly, neutrophilia was more common in patients with systolic dysfunction than the controls (6.6% vs. 34.8%), and was significantly associated with LV systolic dysfunction (p < 0.001). Monocytosis was higher in the controls than the systolic dysfunction group (40.6% vs. 33.3%; p = 0.378).

CONCLUSION

Leucocytosis and neutrophilia in the acute phase of MI are important predictive factors for the development of LV systolic dysfunction. Leucocytosis can be used for risk stratification of such patients.

Relation between white blood cell count and final infarct size in patients with ST-segment elevation acute myocardial infarction undergoing primary percutaneous coronary intervention (from the INFUSE AMI trial)

Although it has been shown that elevated white blood cell count (WBCc) on presentation is associated with an increased risk of cardiac mortality in patients with ST-segment elevation myocardial infarction (STEMI), the responsible mechanisms are unknown. We therefore sought to investigate whether elevated WBCc is associated with increased infarct size measured with cardiac magnetic resonance imaging 30 days after primary percutaneous coronary intervention in the Intracoronary Abciximab and Aspiration Thrombectomy in Patients With Large Anterior Myocardial Infarction trial. INFUSE AMI randomized patients with STEMI and proximal or mid-left anterior descending coronary artery occlusion to bolus intracoronary abciximab versus no abciximab and to manual aspiration versus no aspiration. WBCc at hospital admission was available in 407 of 452 randomized patients. Patients were stratified according to tertiles of WBCc. At 30 days, a significant stepwise increase in infarct size (percentage of total left ventricular mass) was apparent across tertiles of increasing WBCc (median [interquartile range] for tertiles I vs II vs III = 11.2% [3.8% to 19.6%] vs 17.5% [0.5% to 22.9%] vs 19.1% [13.7 to 26.0], respectively, p <0.0001). Absolute infarct mass in grams and abnormal wall motion score were also significantly increased across tertiles of WBC. By multivariate linear regression analysis, WBCc was an independent predictor of infarct size along with intracoronary abciximab randomization, age, time from symptom onset to first device, proximal left anterior descending location, and baseline TIMI flow of 0/1. In conclusion, in patients with anterior wall STEMI, an elevated admission WBCc is a powerful independent predictor of infarct size measured with cardiac magnetic resonance imaging 30 days after primary percutaneous coronary intervention.

Understanding the role of B cells in atherosclerosis: potential clinical implications

Atherosclerosis is a progressive inflammatory disease of the medium to large arteries that is the largest contributor to cardiovascular disease. B-cell subsets have been shown in animal models of atherosclerosis to have both atherogenic and atheroprotective properties. In this review, we highlight the research that developed our understanding of the role of B cells in atherosclerosis both in humans and mice. From this we discuss the potential clinical impact B cells could have both as diagnostic biomarkers and as targets for immunotherapy. Finally, we recognize the inherent difficulty in translating findings from animal models into humans given the differences in both cardiovascular disease and the immune system between mice and humans, making the case for greater efforts at addressing the role of B cells in human atherosclerosis.

Molecular biology of atherosclerosis

At least 468 individual genes have been manipulated by molecular methods to study their effects on the initiation, promotion, and progression of atherosclerosis. Most clinicians and many investigators, even in related disciplines, find many of these genes and the related pathways entirely foreign. Medical schools generally do not attempt to incorporate the relevant molecular biology into their curriculum. A number of key signaling pathways are highly relevant to atherogenesis and are presented to provide a context for the gene manipulations summarized herein. The pathways include the following: the insulin receptor (and other receptor tyrosine kinases); Ras and MAPK activation; TNF-α and related family members leading to activation of NF-κB; effects of reactive oxygen species (ROS) on signaling; endothelial adaptations to flow including G protein-coupled receptor (GPCR) and integrin-related signaling; activation of endothelial and other cells by modified lipoproteins; purinergic signaling; control of leukocyte adhesion to endothelium, migration, and further activation; foam cell formation; and macrophage and vascular smooth muscle cell signaling related to proliferation, efferocytosis, and apoptosis. This review is intended primarily as an introduction to these key signaling pathways. They have become the focus of modern atherosclerosis research and will undoubtedly provide a rich resource for future innovation toward intervention and prevention of the number one cause of death in the modern world.

LDL cholesterol modulates human CD34+ HSPCs through effects on proliferation and the IL-17 G-CSF axis

BACKGROUND

Hypercholesterolemia plays a critical role in atherosclerosis. CD34+ CD45dim Lineage- hematopoietic stem/progenitor cells (HSPCs) give rise to the inflammatory cells linked to atherosclerosis. In mice, high cholesterol levels mobilize HSPCs into the bloodstream, and promote their differentiation to granulocytes and monocytes. The objective of our study was to determine how cholesterol levels affect HSPC quantity in humans.

METHODS

We performed a blinded, randomized hypothesis generating study in human subjects (n=12) treated sequentially with statins of differing potencies to vary lipid levels. CD34+ HSPC levels in blood were measured by flow cytometry. Hematopoietic colony forming assays confirmed the CD34+ population studied as HSPCs with multlineage differentiation potential. Mobilizing cytokine levels were measured by ELISA.

RESULTS

The quantity of HSPCs was 0.15 ± 0.1% of buffy coat leukocytes. We found a weak, positive correlation between CD34+ HSPCs and both total and LDL cholesterol levels (r(2)=0.096, p < 0.025). Additionally, we tested whether cholesterol modulates CD34+ HSPCs through direct effects or on the levels of mobilizing cytokines. LDL cholesterol increased cell surface expression of CXCR4, G-CSFR affecting HSPC migration, and CD47 mediating protection from phagocytosis by immune cells. LDL cholesterol also increased proliferation of CD34+ HSPCs (28 ± 5.7%, n=6, p < 0.03). Finally, the HSPC mobilizing cytokine G-CSF (r(2)=0.0683, p < 0.05), and its upstream regulator IL-17 (r(2)=0.0891, p < 0.05) both correlated positively with LDL cholesterol, while SDF-1 levels were not significantly affected.

CONCLUSIONS

Our findings support a model where LDL cholesterol levels positively correlate with CD34+ HSPC levels in humans through effects on the levels of G-CSF via IL-17 promoting mobilization of HSPCs, and by direct effects of LDL cholesterol on HSPC proliferation. The findings are provocative of further study to determine if HSPCs, like cholesterol levels, are linked to CVD events.

Immunological aspects of atherosclerosis

Cardiovascular disease is the leading cause of death in several countries. The underlying process is atherosclerosis, a slowly progressing chronic disorder that can lead to intravascular thrombosis. There is overwhelming evidence for the underlying importance of our immune system in atherosclerosis. Monocytes, which comprise part of the innate immune system, can be recruited to inflamed endothelium and this recruitment has been shown to be proportional to the extent of atherosclerotic disease. Monocytes undergo migration into the vasculature, they differentiate into macrophage phenotypes, which are highly phagocytic and can scavenge modified lipids, leading to foam cell formation and development of the lipid-rich atheroma core. This increased influx leads to a highly inflammatory environment and along with other immune cells can increase the risk in the development of the unstable atherosclerotic plaque phenotype. The present review provides an overview and description of the immunological aspect of innate and adaptive immune cell subsets in atherosclerosis, by defining their interaction with the vascular environment, modified lipids and other cellular exchanges. There is a particular focus on monocytes and macrophages, but shorter descriptions of dendritic cells, lymphocyte populations, neutrophils, mast cells and platelets are also included.

Acat1 gene ablation in mice increases hematopoietic progenitor cell proliferation in bone marrow and causes leukocytosis

OBJECTIVE

To investigate the role of acyl-CoA:cholesterol acyltransferase 1 (ACAT1) in hematopoiesis.

APPROACH AND RESULTS

ACAT1 converts cellular cholesterol to cholesteryl esters for storage in multiple cell types and is a potential drug target for human diseases. In mouse models for atherosclerosis, global Acat1 knockout causes increased lesion size; bone marrow transplantation experiments suggest that the increased lesion size might be caused by ACAT1 deficiency in macrophages. However, bone marrow contains hematopoietic stem cells that give rise to cells in myeloid and lymphoid lineages; these cell types affect atherosclerosis at various stages. Here, we test the hypothesis that global Acat1(-/-) may affect hematopoiesis, rather than affecting macrophage function only, and show that Acat1(-/-) mice contain significantly higher numbers of myeloid cells and other cells than wild-type mice. Detailed analysis of bone marrow cells demonstrated that Acat1(-/-) causes a higher proportion of the stem cell-enriched Lin(-)Sca-1(+)c-Kit(+) population to proliferate, resulting in higher numbers of myeloid progenitor cells. In addition, we show that Acat1(-/-) causes higher monocytosis in Apoe(-/-) mouse during atherosclerosis development.

CONCLUSIONS

ACAT1 plays important roles in hematopoiesis in normal mouse and in Apoe(-/-) mouse during atherosclerosis development.

Cardioprotective functions of HDLs

Multiple human population studies have established the concentration of high density lipoprotein (HDL) cholesterol as an independent, inverse predictor of the risk of having a cardiovascular event. Furthermore, HDLs have several well-documented functions with the potential to protect against cardiovascular disease. These include an ability to promote the efflux of cholesterol from macrophages in the artery wall, inhibit the oxidative modification of low density lipoproteins (LDLs), inhibit vascular inflammation, inhibit thrombosis, promote endothelial repair, promote angiogenesis, enhance endothelial function, improve diabetic control, and inhibit hematopoietic stem cell proliferation. There are undoubtedly other beneficial functions of HDLs yet to be identified. The HDL fraction in human plasma is heterogeneous, consisting of several subpopulations of particles of varying size, density, and composition. The functions of the different HDL subpopulations remain largely unknown. Given that therapies that increase the concentration of HDL cholesterol have varying effects on the levels of specific HDL subpopulations, it is of great importance to understand how distribution of different HDL subpopulations contribute to the potentially cardioprotective functions of this lipoprotein fraction. This review summarizes current understanding of the relationship of HDL subpopulations to their cardioprotective properties and highlights the gaps in current knowledge regarding this important aspect of HDL biology.

Pathophysiological role of neutrophils in acute myocardial infarction

The pathogenesis of acute myocardial infarction is known to be mediated by systemic, intraplaque and myocardial inflammatory processes. Among different immune cell subsets, compelling evidence now indicates a pivotal role for neutrophils in acute coronary syndromes. Neutrophils infiltrate coronary plaques and the infarcted myocardium and mediate tissue damage by releasing matrix-degrading enzymes and reactive oxygen species. In addition, neutrophils are also involved in post-infarction adverse cardiac remodelling and neointima formation after angioplasty. The promising results obtained in preclinical modelswith pharmacological approaches interfering with neutrophil recruitment or function have confirmed the pathophysiological relevance of these immune cells in acute coronary syndromes and prompted further studies of these therapeutic interventions. This narrative review will provide an update on the role of neutrophils in acute myocardial infarction and on the pharmacological means that were devised to prevent neutrophil-mediated tissue damage and to reduce post-ischaemic outcomes.

Hyperglycemia promotes myelopoiesis and impairs the resolution of atherosclerosis

Diabetes is a major risk factor for atherosclerosis. Although atherosclerosis is initiated by deposition of cholesterol-rich lipoproteins in the artery wall, the entry of inflammatory leukocytes into lesions fuels disease progression and impairs resolution. We show that diabetic mice have increased numbers of circulating neutrophils and Ly6-C(hi) monocytes, reflecting hyperglycemia-induced proliferation and expansion of bone marrow myeloid progenitors and release of monocytes into the circulation. Increased neutrophil production of S100A8/S100A9, and its subsequent interaction with the receptor for advanced glycation end products on common myeloid progenitor cells, leads to enhanced myelopoiesis. Treatment of hyperglycemia reduces monocytosis, entry of monocytes into atherosclerotic lesions, and promotes regression. In patients with type 1 diabetes, plasma S100A8/S100A9 levels correlate with leukocyte counts and coronary artery disease. Thus, hyperglycemia drives myelopoiesis and promotes atherogenesis in diabetes.

Association among leukocyte count, mortality, and bleeding in patients with non-ST-segment elevation acute coronary syndromes (from the Acute Catheterization and Urgent Intervention Triage StrategY [ACUITY] trial)

Although inflammation is involved in the pathogenesis of acute coronary syndromes, the extent of inflammation is not routinely assessed, and its prognostic implications in patients with non-ST-segment elevation acute coronary syndrome have not been investigated in depth. We analyzed the prognostic implications of an elevated white blood cell count (WBCc) in patients with moderate and high-risk non-ST-segment elevation acute coronary syndrome undergoing an early invasive strategy in the large-scale Acute Catheterization and Urgent Intervention Triage StrategY trial. The WBCc at admission was available for 13,678 of 13,819 patients (98.9%). The patients in the upper tertile of the WBCc had an increased risk of 30-day major bleeding, 1-year mortality, and definite/probable stent thrombosis compared to those in the mid or lower tertiles. On multivariate analysis, the WBCc was an independent predictor of 30-day major bleeding and 1-year cardiac, noncardiac, and all-cause mortality. The association between the WBCc and cardiac mortality was present in multiple prespecified subgroups, with no significant interaction between the WBCc and age, gender, diabetes, smoking, renal dysfunction, elevated baseline biomarkers, antithrombotic therapy, revascularization, and Thrombolysis In Myocardial Infarction risk score. The WBCc remained an independent predictor of mortality after adjusting for bleeding, C-reactive protein level, and angiographic variables, including left ventricular ejection fraction, Thrombolysis In Myocardial Infarction flow, and number of diseased vessels. The WBCc significantly improved the prognostic accuracy of the Thrombolysis In Myocardial Infarction risk score, with a net reclassification improvement of 11% (p <0.0001). In conclusion, in patients with moderate- and high-risk non-ST-segment elevation acute coronary syndrome, an elevated admission WBCc was an independent predictor of 30-day major bleeding, and 1-year cardiac, noncardiac, and all-cause mortality.

Making a difference: monocyte heterogeneity in cardiovascular disease

Monocytes are frequently described as bone marrow-derived precursors of macrophages. Although many studies support this view, we now appreciate that monocytes neither develop exclusively in the bone marrow nor give rise to all macrophages and dendritic cells. In addition to differentiating to specific leukocyte populations, monocytes, as monocytes, are functionally and ontogenically heterogeneous. In this review we will focus on the development and activity of monocytes and their subsets in mice (Ly-6 C(high/low)) and humans (CD14(+/dim/-) CD16(+/-)) in the context of atherosclerosis and its complications.

Circadian control of the immune system

Circadian rhythms, which have long been known to play crucial roles in physiology, are emerging as important regulators of specific immune functions. Circadian oscillations of immune mediators coincide with the activity of the immune system, possibly allowing the host to anticipate and handle microbial threats more efficiently. These oscillations may also help to promote tissue recovery and the clearance of potentially harmful cellular elements from the circulation. This Review summarizes the current knowledge of circadian rhythms in the immune system and provides an outlook on potential future implications.

Baseline white blood cell count is an independent predictor of long-term cardiovascular mortality in patients with non-ST-segment elevation acute coronary syndrome, but it does not improve the risk classification of the GRACE score

OBJECTIVES

To investigate the prognostic significance of baseline white blood cell count (WBCc) in non-ST-segment elevation acute coronary syndrome (NSTE-ACS) and its additive predictive value beyond the Global Registry of Acute Coronary Events (GRACE) score.

METHODS

We included 1,315 consecutive NSTE-ACS patients. Patients were divided in quartiles according to the WBCc (cells per 1 mm(3)) i.e. Q1 <6,850, Q2 = 6,850-8,539, Q3 = 8,540-10,857 and Q4 ≥10,858. The study end point was 3-year cardiovascular death (CVD).

RESULTS

The median age of the study population was 76 years. Overall, 335 patients (25.5%) died with 211 of these (16%) suffering from CVD. Patients in Q4 showed a higher cumulative probability of CVD compared to patients in Q1-Q3. On multivariable analysis, patients in Q4 were at higher risk of CVD [hazard ratio (HR) = 1.47, 95% confidence interval (CI) 1.09-1.98, p = 0.011]. WBCc as a continuous variable was also independently associated with the study end point (HR = 1.043; 95% CI 1.02-1.07; p = 0.001). However, the incorporation of WBCc into the GRACE score did not improve either prediction of risk (C-index = 0.796 for GRACE score with or without WBCc) or classification of risk [relative integrated discrimination improvement = 0.0154, 95% CI) -0.029 to 0.0618; continuous net reclassification improvement = -0.0676, 95% CI -0.2149-0.0738).

CONCLUSIONS

WBCc was an independent predictor of 3-year CVD in patients with NSTE-ACS. However, it did not add prognostic information beyond the GRACE score.

Stroke seasonality associations with subtype, etiology and laboratory results in the Ludwigshafen Stroke Study (LuSSt)

Data on seasonal differences in stroke incidence are conflicting. Little is known about seasonal variability in etiological stroke subtypes and population-based data on possible trigger factors are lacking. The Ludwigshafen Stroke Study is a prospective population-based stroke registry. All residents of the city of Ludwigshafen who suffer from acute stroke or TIA are registered. Patients with first-ever stroke (FES) were included for the present analysis. Between January 1, 2006 and December 31st, 2010, 1,779 patients (age 71.7 ± 13.4 years (mean + standard deviation; 897 (50.4 %) women) suffered a FES. Incidence for FES was lowest in summer (reference) with significantly higher rates in winter (rate ratio (RR) 1.20, 95 % confidence interval (CI) 1.05-1.37) and spring (RR 1.21 95 % CI 1.06-1.38). First-ever ischemic stroke (FEIS) was more common in winter (RR 1.16, 95 %CI 1.01-1.34) and first-ever intracerebral haemorrhage (FE-ICH) was more frequent in spring (RR 2.0, 95 %CI 1.24-3.22) than in summer. In FES, systolic and diastolic blood pressure on admission (SBP/DBP) showed significant variation with lowest values in summer (SBP: p = 0.02; DBP p = 0.05). In subtypes of FEIS, cardioembolism tended to be more common in winter (p = 0.14). There were no differences in risk factor prevalence between seasons. Leukocyte count on admission was lowest in summer (8.2 ± 1.4/μl) and highest in winter (8.9 ± 1.9/μl; p = 0.008). The hematocrit showed a similar trend (p = 0.06). Our data show higher incidence rates for FES in winter and spring, for FEIS in winter and for FE-ICH in spring. Variations in blood pressure on admission and leukocyte counts were associated with these findings and may possibly contribute to seasonal stroke variability.

Relationship between mean platelet volume and low-grade systemic coagulation with vitamin D deficiency in primary ovarian insufficiency

OBJECTIVE

Premature menopause in young women is associated with an increased incidence of cardiovascular disease. The present study was designed to determine vitamin D (vit D) and the coagulation parameters such as activated partial thromboplastin time (APTT), PT, D-dimer, white blood cell (WBC), and mean platelet volume (MPV) levels, in primary ovarian insufficiency (POI) patients and control women with a normal menstrual cycle.

MATERIALS AND METHODS

A total of 43 patients with non-diabetic POI were studied in order to evaluate and compare with the control group comprising 33 women with a normal menstrual cycle.

RESULTS

There was no significant difference between the groups for age and body mass index (BMI). D-dimer, WBC, MPV, PT, total cholesterol, and LDL cholesterol were higher in women with POI. APTT levels were also increased but missed the significance in POI group. Women with POI had significantly lower serum vit D levels compared with healthy control group. FSH level was positively correlated with D-dimer, WBC, MPV, and negatively correlated to vit D and serum D vit level was inversely correlated with MPV, APTT, D-dimer, FSH levels in individual women.

CONCLUSIONS

The obtained results seem to indicate that POI patients had low-grade systemic coagulation and fibrinolytic activation as evidenced by elevated D-dimer, WBC, MPV, PT values potentially be used as indicators of risk factor for thrombosis and atherosclerosis in POI women. All of our patients with POI were deficient in vit D. These results also suggest that vit D deficiency plays important roles of POI women and associated with coagulation, independently from age and BMI.

Leukocyte and leukocyte subset counts reveal compensatory mechanisms in coronary heart disease

BACKGROUND

Leukocyte number in the circulation plays a central role in inflammatory diseases, such as coronary heart disease (CHD). Increased counts are correlated with the intensity of the peri-infarction inflammatory response and adverse outcomes. We investigated leukocyte and leukocyte subset counts in dyslipidaemia patients and their relationship with LDL oxidation.

METHODS

Dyslipidaemia patients (207) were selected for blood counts and LDL-C testing. The level of HNP-1and myeloperoxidase in subsets of leukocytes and their relationship with LDL oxidation were compared between 24 CHD patients and 24 normal controls.

RESULTS

In dyslipidaemia patients, total leukocyte and neutrophil counts increased with LDL-C (p=0.001). Monocyte counts showed the opposite trend (p=0.001). Although serum HNP-1 levels were not different between CHD patients and normal controls (p=0.558), neutrophil HNP-1 mRNA levels were 2.13-fold greater than those of normal controls. However, monocyte HNP-1 mRNA levels were lower (p=0.005). The distribution of myeloperoxidase in monocytes and neutrophils is different, myeloperoxidase locates mainly in the cytoplasm of monocytes, on the cell membrane of neutrophils.

CONCLUSIONS

Leukocyte and leukocyte subset counts may correlate with LDL-C levels and LDL oxidation. The monocyte-neutrophil interaction reveals a potential compensatory mechanism associated with LDL oxidation in CHD that may be a prognostic factor of CHD.

Platelet-leukocyte crosstalk: Linking proinflammatory responses to procoagulant state

Platelet activation is known to be associated with the release of a vast array of chemokines and proinflammatory lipids which induce pleiotropic effects on a wide variety of tissues and cells, including leukocytes. During thrombosis, the recruitment of leukocytes to activated platelets is considered an important step which not only links thrombosis to inflammatory responses but may also enhance procoagulant state. This phenomenon is highly regulated and influenced by precise mutual interactions between the cells at site of vascular injury and thrombi formation. Platelet-leukocyte interaction involves a variety of mediators including adhesion molecules, chemokines and chemoattractant molecules, shed proteins, various proinflammatory lipids and other materials. The current review addresses the detailed mechanisms underlying platelet-leukocyte crosstalk. This includes their adhesive interactions, transcellular metabolisms, induced tissue factor activity and neutrophil extracellular traps formation as well as the impacts of these phenomena in modulation of the proinflammatory and procoagulant functions in a reciprocal manner that enhances the physiological responses.

MicroRNA-33 deficiency reduces the progression of atherosclerotic plaque in ApoE-/- mice

Background

Cholesterol efflux from cells to apolipoprotein A-I (apoA-I) acceptors via the ATP-binding cassette transporters ABCA1 and ABCG1 is thought to be central in the antiatherogenic mechanism. MicroRNA (miR)-33 is known to target ABCA1 and ABCG1 in vivo.

Methods and Results

We assessed the impact of the genetic loss of miR-33 in a mouse model of atherosclerosis. MiR-33 and apoE double-knockout mice (miR-33^−/−Apoe^−/−) showed an increase in circulating HDL-C levels with enhanced cholesterol efflux capacity compared with miR-33^+/+Apoe^−/− mice. Peritoneal macrophages from miR-33^−/−Apoe^−/− mice showed enhanced cholesterol efflux to apoA-I and HDL-C compared with miR-33^+/+Apoe^−/− macrophages. Consistent with these results, miR-33^−/−Apoe^−/− mice showed reductions in plaque size and lipid content. To elucidate the roles of miR-33 in blood cells, bone marrow transplantation was performed in these mice. Mice transplanted with miR-33^−/−Apoe^−/− bone marrow showed a significant reduction in lipid content in atherosclerotic plaque compared with mice transplanted with miR-33^+/+Apoe^−/− bone marrow, without an elevation of HDL-C. Some of the validated targets of miR-33 such as RIP140 (NRIP1) and CROT were upregulated in miR-33^−/−Apoe^−/− mice compared with miR-33^+/+Apoe^−/− mice, whereas CPT1a and AMPKα were not.

Conclusions

These data demonstrate that miR-33 deficiency serves to raise HDL-C, increase cholesterol efflux from macrophages via ABCA1 and ABCG1, and prevent the progression of atherosclerosis. Many genes are altered in miR-33-deficient mice, and detailed experiments are required to establish miR-33 targeting therapy in humans.

Hematopoietic stem/progenitor cell proliferation and differentiation is differentially regulated by high-density and low-density lipoproteins in mice

Rationale

Hematopoietic stem/progenitor cells (HSPC) are responsible for maintaining the blood system as a result of their self-renewal and multilineage differentiation capacity. Recently, studies have suggested that HDL cholesterol may inhibit and impaired cholesterol efflux may increase HSPC proliferation and differentiation.

Objectives

We hypothesized that LDL may enhance HSPC proliferation and differentiation while HDL might have the opposing effect which might influence the size of the pool of inflammatory cells.

Methods and Results

HSPC number and function were studied in hypercholesterolemic LDL receptor knockout (LDLr^−/−) mice on high fat diet. Hypercholesterolemia was associated with increased frequency of HSPC, monocytes and granulocytes in the peripheral blood (PB). In addition, an increased proportion of BM HSPC was in G₂M of the cell cycle, and the percentage of HSPC and granulocyte-macrophage progenitors (GMP) increased in BM of LDLr^−/− mice. When BM Lin-Sca-1+cKit+ (i.e. “LSK”) cells were cultured in the presence of LDL in vitro we also found enhanced differentiation towards monocytes and granulocytes. Furthermore, LDL promoted lineage negative (Lin−) cells motility. The modulation by LDL on HSPC differentiation into granulocytes and motility was inhibited by inhibiting ERK phosphorylation. By contrast, when mice were infused with human apoA-I (the major apolipoprotein of HDL) or reconstituted HDL (rHDL), the frequency and proliferation of HSPC was reduced in BM in vivo. HDL also reversed the LDL-induced monocyte and granulocyte differentiation in vitro.

Conclusion

Our data suggest that LDL and HDL have opposing effects on HSPC proliferation and differentiation. It will be of interest to determine if breakdown of HSPC homeostasis by hypercholesterolemia contributes to inflammation and atherosclerosis progression.

Prothrombin activation in blood coagulation: the erythrocyte contribution to thrombin generation

Prothrombin activation can proceed through the intermediates meizothrombin or prethrombin-2. To assess the contributions that these 2 intermediates make to prothrombin activation in tissue factor (Tf)-activated blood, immunoassays were developed that measure the meizothrombin antithrombin (mTAT) and α-thrombin antithrombin (αTAT) complexes. We determined that Tf-activated blood produced both αTAT and mTAT. The presence of mTAT suggested that nonplatelet surfaces were contributing to approximately 35% of prothrombin activation. Corn trypsin inhibitor-treated blood was fractionated to yield red blood cells (RBCs), platelet-rich plasma (PRP), platelet-poor plasma (PPP), and buffy coat. Compared with blood, PRP reconstituted with PPP to a physiologic platelet concentration showed a 2-fold prolongation in the initiation phase and a marked decrease in the rate and extent of αTAT formation. Only the addition of RBCs to PRP was capable of normalizing αTAT generation. FACS on glycophorin A-positive cells showed that approximately 0.6% of the RBC population expresses phosphatidylserine and binds prothrombinase (FITC Xa·factor Va). These data indicate that RBCs participate in thrombin generation in Tf-activated blood, producing a membrane that supports prothrombin activation through the meizothrombin pathway.

Adrenergic nerves govern circadian leukocyte recruitment to tissues

The multistep sequence leading to leukocyte migration is thought to be locally regulated at the inflammatory site. Here, we show that broad systemic programs involving long-range signals from the sympathetic nervous system (SNS) delivered by adrenergic nerves regulate rhythmic recruitment of leukocytes in tissues. Constitutive leukocyte adhesion and migration in murine bone marrow (BM) and skeletal-muscle microvasculature fluctuated with circadian peak values at night. Migratory oscillations, altered by experimental jet lag, were implemented by perivascular SNS fibers acting on β-adrenoreceptors expressed on nonhematopoietic cells and leading to tissue-specific, differential circadian oscillations in the expression of endothelial cell adhesion molecules and chemokines. We showed that these rhythms have physiological consequences through alteration of hematopoietic cell recruitment and overall survival in models of septic shock, sickle cell vaso-occlusion, and BM transplantation. These data provide unique insights in the leukocyte adhesion cascade and the potential for time-based therapeutics for transplantation and inflammatory diseases.

Perspectives on chronic inflammation in essential thrombocythemia, polycythemia vera, and myelofibrosis: is chronic inflammation a trigger and driver of clonal evolution and development of accelerated atherosclerosis and second cancer?

The morbidity and mortality of patients with the chronic Philadelphia-negative myeloproliferative neoplasms (MPNs), essential thrombocythemia, polycythemia vera, and primary myelofibrosis are mainly caused by cardiovascular diseases, thrombohemorrhagic complications, and bone marrow failure because of myelofibrosis and leukemic transformation. In the general population, chronic inflammation is considered of major importance for the development of atherosclerosis and cancer. MPNs are characterized by a state of chronic inflammation, which is proposed to be the common denominator for the development of “premature atherosclerosis,” clonal evolution, and second cancer in patients with MPNs. Chronic inflammation may both initiate clonal evolution and catalyze its expansion from early disease stage to the myelofibrotic burnt-out phase. Furthermore, chronic inflammation may also add to the severity of cardiovascular disease burden by accelerating the development of atherosclerosis, which is well described and recognized in other chronic inflammatory diseases. A link between chronic inflammation, atherosclerosis, and second cancer in MPNs favors early intervention at the time of diagnosis (statins and interferon-α2), the aims being to dampen chronic inflammation and clonal evolution and thereby also diminish concurrent disease-mediated chronic inflammation and its consequences (accelerated atherosclerosis and second cancer).

Risk factors for lower extremity amputation in diabetic foot disease categorized by Wagner classification

AIMS

To elucidate the risk factors for lower extremity amputation (LEA) in patients of diabetic foot disease with different Wagner gradings.

METHODS

This study was conducted in a multidisciplinary diabetic foot care center. Demographic characteristics, laboratory data, disease history, ankle brachial pressure index (ABI) and Wagner classification were considered as independent variables to predict the therapeutic outcome (major LEA, minor LEA, and non-amputation). Risk factors for LEA in different Wagner grades were further analyzed. Multivariate stepwise ordinal logistic regression was performed.

RESULTS

Of 789 study subjects, 19.9% received major LEA and 22.9% received minor LEA. Higher Wagner grade, lower ABI, serum albumin and hemoglobin, and elevated white blood cell (WBC) count were significantly associated with an increased risk of LEA. When stratified by Wagner classification, most of the above predictors and estimated glomerular filtration (eGFR) were detected only in grade 3. While in grades 2 and 4, WBC count was identified as primary predictor positively associated with an increased risk of LEA.

CONCLUSIONS

Wagner classification remarkably influenced the potential risk factors for LEA, showing different predictors in different grades. The traditionally recognized predictors for diabetic foot amputation such as lower ABI, albumin or eGFR were almost exclusively found in patients with Wagner grade 3.

Higher leukocyte count is associated with higher risk of 3-year mortality in non-diabetic patients with first-ever ischemic stroke

Leukocyte count predicted the risk of first-time myocardial infarction and ischemic stroke. The aim of this study was to determine the role of elevated leukocyte count in non-diabetic patients admitted for acute first-ever ischemic stroke on clinical presentation and 3-year mortality. We studied 462 patients with acute first-ever ischemic stroke without diabetes mellitus or active infection at admission. Patients were classified into 2 groups according to their leukocyte count. A white blood cell (WBC) count ≥ 10,000/μL was defined as an elevated leukocyte count, otherwise as normal. Clinical presentation, risk factors for stroke, laboratory data, co-morbidities, and outcomes were recorded. 64 patients (13.9%) had elevated leukocytes. Multivariate logistic regression showed that an elevated platelet count was positively associated with the elevated leukocyte count, while a low serum sodium level was negatively associated with an elevated leukocyte count (P=0.008, P=0.003, respectively). An elevated leukocyte count was associated with a higher risk of a stroke in evolution (P=0.021). Multivariate Cox regression analysis revealed that an elevated leukocyte count is a significant predictor of 3-year mortality [P=0.010, HR=3.26 (1.33-7.98)]. In conclusion, higher leukocyte counts during the acute stroke stage are associated with increased risk of 3-year mortality in patients with acute, first-ever ischemic stroke.

Cdkn2a is an atherosclerosis modifier locus that regulates monocyte/macrophage proliferation

OBJECTIVE

Common genetic variants in a 58-kb region of chromosome 9p21, near the CDKN2A/CDKN2B tumor suppressor locus, are strongly associated with coronary artery disease. However, the underlying mechanism of action remains unknown.

METHODS AND RESULTS

We previously reported a congenic mouse model harboring an atherosclerosis susceptibility locus and the region of homology with the human 9p21 locus. Microarray and transcript-specific expression analyses showed markedly decreased Cdkn2a expression, including both p16(INK4a) and p19(ARF), but not Cdkn2b (p15(INK4b)), in macrophages derived from congenic mice compared with controls. Atherosclerosis studies in subcongenic strains revealed genetic complexity and narrowed 1 locus to a small interval including Cdkn2a/b. Bone marrow (BM) transplantation studies implicated myeloid lineage cells as the culprit cell type, rather than resident vascular cells. To directly test the role of BM-derived Cdkn2a transcripts in atherogenesis and inflammatory cell proliferation, we performed a transplantation study using Cdkn2a(-/-) cells in the Ldlr(-/-) mouse model. Cdkn2a-deficient BM recipients exhibited accelerated atherosclerosis, increased Ly6C proinflammatory monocytes, and increased monocyte/macrophage proliferation compared with controls.

CONCLUSION

These data provide a plausible mechanism for accelerated atherogenesis in susceptible congenic mice, involving decreased expression of Cdkn2a and increased proliferation of monocyte/macrophages, with possible relevance to the 9p21 human locus.

Effects of high adherence to mediterranean or low-fat diets in medicated secondary prevention patients

Although the Mediterranean diet (MD) and the low-fat Therapeutic Lifestyle Changes Diet (TLCD) promote equivalent increases in event-free survival in secondary coronary prevention, possible mechanisms of such complete dietary patterns in these patients, usually medicated, are unclear. The aim of this study was to investigate the effects of the MD versus the TLCD in markers of endothelial function, oxidative stress, and inflammation after acute coronary syndromes. Comparison was made between 3 months of the MD (n = 21; rich in whole grains, vegetables, fruits, nuts, and olive oil, plus red wine) and the TLCD (n = 19; plus phytosterols 2 g/day) in a highly homogenous population of stable patients who experienced coronary events in the previous 2 years (aged 45 to 65 years, all men) allocated to each diet under a strategy designed to optimize adherence, documented as >90%. Baseline demographics, body mass index and clinical data, and use of statins and other drugs were similar between groups. The MD and TLCD promoted similar decreases in body mass index and blood pressure (p ≤0.001) and particularly in plasma asymmetric dimethylarginine levels (p = 0.02) and l-arginine/asymmetric dimethylarginine ratios (p = 0.01). The 2 diets did not further enhance flow-mediated brachial artery dilation compared to baseline (4.4 ± 4.0%). Compared to the TLCD, the MD promoted decreases in blood leukocyte count (p = 0.025) and increases in high-density lipoprotein levels (p = 0.053) and baseline brachial artery diameter. Compared to the MD, the TLCD decreased low-density lipoprotein and oxidized low-density lipoprotein plasma levels, although the ratio of oxidized to total low-density lipoprotein remained unaltered. Glucose, high-sensitivity C-reactive protein, triglycerides, myeloperoxidase, intercellular adhesion molecular, vascular cell adhesion molecule, and glutathione serum and plasma levels remained unchanged with either diet. In conclusion, medicated secondary prevention patients show evident although small responses to the MD and the TLCD, with improved markers of redox homeostasis and metabolic effects potentially related to atheroprotection.

ApoE regulates hematopoietic stem cell proliferation, monocytosis, and monocyte accumulation in atherosclerotic lesions in mice

Leukocytosis is associated with increased cardiovascular disease risk in humans and develops in hypercholesterolemic atherosclerotic animal models. Leukocytosis is associated with the proliferation of hematopoietic stem and multipotential progenitor cells (HSPCs) in mice with deficiencies of the cholesterol efflux-promoting ABC transporters ABCA1 and ABCG1 in BM cells. Here, we have determined the role of endogenous apolipoprotein-mediated cholesterol efflux pathways in these processes. In Apoe⁻/⁻ mice fed a chow or Western- type diet, monocytosis and neutrophilia developed in association with the proliferation and expansion of HSPCs in the BM. In contrast, Apoa1⁻/⁻ mice showed no monocytosis compared with controls. ApoE was found on the surface of HSPCs, in a proteoglycan-bound pool, where it acted in an ABCA1- and ABCG1-dependent fashion to decrease cell proliferation. Accordingly, competitive BM transplantation experiments showed that ApoE acted cell autonomously to control HSPC proliferation, monocytosis, neutrophilia, and monocyte accumulation in atherosclerotic lesions. Infusion of reconstituted HDL and LXR activator treatment each reduced HSPC proliferation and monocytosis in Apoe⁻/⁻ mice. These studies suggest a specific role for proteoglycanbound ApoE at the surface of HSPCs to promote cholesterol efflux via ABCA1/ABCG1 and decrease cell proliferation, monocytosis, and atherosclerosis. Although endogenous apoA-I was ineffective, pharmacologic approaches to increasing cholesterol efflux suppressed stem cell proliferative responses.

Monocytes link atherosclerosis and cancer

From many perspectives, cardiovascular diseases and cancers are fundamentally different. On the one hand, atherosclerosis is a disease of lipid accumulation driven by diet and lifestyle, whereas cancer is an attack "from within" driven by mutations. Nevertheless, studies over the past 20 years have forced us to re-evaluate such a view. We are learning that, among other factors, the immune system is indispensable for the development and progression of both diseases. Its components are not only reactive but can also orchestrate both tumor and atherosclerotic lesion growth. In this Viewpoint, we explore how monocytes, which are key constituents of the immune system, forge links between cardiovascular diseases and cancers.

Platelet-leukocyte interactions in thrombosis

Activated platelets may adhere to leukocytes and form circulating mixed aggregates. The latter are considered a reliable marker of a prothrombotic state and are associated with several cardiovascular conditions. The molecular mechanisms responsible of this cellular interaction include a central role of platelet P-selectin and of P-selectin glycoprotein ligand-1 (PSGL-1), its counter receptor on leukocytes in a signaling cascade, resulting in the activation of the beta-2 integrin Mac-1 and in the firm adhesion between the two cell types. The interaction of P-selectin with PSGL-1 also induces upregulation of leukocyte tissue factor, biosynthesis of several cytokines and other inflammatory reactions, thereby contributing to the thrombotic progression. In this review the main determinants of mixed aggregate formation, the heritability component, the major pathological conditions associated with higher levels of mixed aggregates in the circulation will be discussed. Besides current anti-platelet or antithrombotic drugs, natural compounds, such as the polyphenols present in vegetable foods and red wine, have been tested for their inhibitory effect on mixed aggregate formation. The promising results shown by studies in vitro and in experimental animal models, remain to be carefully investigated in humans. Platelet-leukocyte aggregates provide a novel link between inflammation and thrombosis, two central processes in atherogenesis. A better understanding of the role of platelet-leukocyte interactions in athero-thrombosis will be instrumental for the progress of prevention and treatment of ischaemic cardiovascular disease.

ApoE suppresses atherosclerosis by reducing lipid accumulation in circulating monocytes and the expression of inflammatory molecules on monocytes and vascular endothelium

OBJECTIVE

We investigated atheroprotective properties of apolipoprotein (apo) E beyond its ability to lower plasma cholesterol. We hypothesized that apoE reduces atherosclerosis by decreasing lipid accumulation in circulating monocytes and the inflammatory state of monocytes and the vascular endothelium.

METHODS AND RESULTS

We developed mice with spontaneous hyperlipidemia with and without plasma apoE. Hypomorphic apoE mice deficient in low-density lipoprotein receptor (Apoe(h/h)Ldlr(-/-)) were compared to Apoe(-/-)Ldlr(-/-) mice. Despite 4-fold more plasma apoE than WT mice, Apoe(h/h)Ldlr(-/-) mice displayed similar plasma cholesterol as Apoe(-/-) Ldlr(-/-) mice but developed 4-fold less atherosclerotic lesions by 5 months of age. The aortic arch of Apoe(h/h)Ldlr(-/-) mice showed decreased endothelial expression of ICAM-1, PECAM-1, and JAM-A. In addition, Apoe(h/h)Ldlr(-/-) mice had less circulating leukocytes and proinflammatory Ly6C(high) monocytes. These monocytes had decreased neutral lipid content and reduced surface expression of ICAM-1, VLA-4, and L-Selectin. Apoe(h/h)Ldlr(-/-) mice displayed increased levels of apoA1-rich HDL that were potent in promoting cellular cholesterol efflux.

CONCLUSIONS

Our findings suggest that apoE reduces atherosclerosis in the setting of hyperlipidemia by increasing plasma apoA1-HDL that likely contribute to reduce intracellular lipid accumulation and thereby the activation of circulating leukocytes and the vascular endothelium.

Characterization of resident surgeon participation during carotid endarterectomy and impact on perioperative outcomes

INTRODUCTION

The impact of resident surgeon participation during vascular procedures on postoperative outcomes is incompletely understood. We characterized resident physician participation during carotid endarterectomy (CEA) procedures within the 2005-2009 American College of Surgeons National Surgical Quality Improvement Participant Use Datafile and evaluated associations with procedural characteristics and perioperative adverse events.

METHODS

CEAs were identified using primary current procedural terminology codes; those performed simultaneously with other major procedures or unknown resident participation status were excluded. Group-wise comparisons based on resident participation status were performed using χ(2) or Fisher's exact test for categorical variables and t tests or nonparametric methods for continuous variables. Associations with perioperative adverse events (major = stroke, death, myocardial infarction, or cardiac arrest; minor = peripheral nerve injury, bleeding requiring transfusion, surgical site infection, or wound disruption) were assessed using multivariable logistic regression models adjusting for other known risk factors.

RESULTS

A total of 25,280 CEA procedures were analyzed, of which residents participated in 13,705 (54.2%), while residents were absent in 11,575 (45.8%). Among CEAs with resident physician participation, resident level was categorized as junior (postgraduate year [PGY] 1-2) in 21.9%, senior (PGY 3-5) in 52.7%, and fellow (PGY ≥6) in 25.3%. Major adverse event rates with and without resident participation were 1.9% versus 2.1%, and minor adverse event rates with and without resident participation were 0.9% versus 1.0%, respectively. In multivariable models, resident physician participation was not associated with perioperative risk for major adverse events (odds ratio [OR], 0.90; 95% confidence interval [CI], 0.75-1.08) or minor adverse events (OR, 0.93; 95% CI, 0.72-1.21).

CONCLUSIONS

Resident surgeon participation during CEA is not associated with risk of adverse perioperative events.

Neutrophils and clinical outcomes in patients with acute coronary syndromes and/or cardiac revascularisation. A systematic review on more than 34,000 subjects

Some studies have suggested that high levels of total white blood cell (WBC) count and C-reactive protein (CRP) may be considered as independent prognostic factors in patients with acute coronary syndromes (ACS) and/or after cardiac revascularisation by percutaneous coronary intervention or coronary artery bypass grafting surgery. Evidence on the role of neutrophils in cardiovascular disease is less compelling. Therefore, we conducted a systematic review of the literature with the aim of identifying all the available evidence to clarify the role of neutrophils (absolute or relative count, neutrophil/lymphocyte ratio) as a prognostic risk factor in patients with ACS and/or cardiac revascularisation. All published studies evaluating the role of neutrophils as a risk factor for clinical outcomes were assessed using the MEDLINE and EMBASE databases. Study selection, data extraction and validity assessment was performed independently by two reviewers. Twenty-one studies (17 of which had positive results) for a total of more than 34,000 patients were included. Ten of 13 studies in ACS patients found that neutrophils measured on-admission are related to mortality rate and/or to major adverse clinical events. A predictive value of neutrophils after cardiac revascularisation procedures was reported in seven out of eight studies. Most of the studies showed that neutrophils were independent predictors of cardiovascular outcomes when analysed concomitantly with other markers of inflammation (WBC, CRP). The findings of our systematic review highlight the potential application of this inexpensive and readily available inflammatory marker for risk stratification in patients with ACS and/or cardiac revascularisation.

Human neutrophil peptides mediate endothelial-monocyte interaction, foam cell formation, and platelet activation

OBJECTIVE

Neutrophils are involved in the inflammatory responses during atherosclerosis. Human neutrophil peptides (HNPs) released from activated neutrophils exert immune modulating properties. We hypothesized that HNPs play an important role in neutrophil-mediated inflammatory cardiovascular responses in atherosclerosis.

METHODS AND RESULTS

We examined the role of HNPs in endothelial-leukocyte interaction, platelet activation, and foam cell formation in vitro and in vivo. We demonstrated that stimulation of human coronary artery endothelial cells with clinically relevant concentrations of HNPs resulted in monocyte adhesion and transmigration; induction of oxidative stress in human macrophages, which accelerates foam cell formation; and activation and aggregation of human platelets. The administration of superoxide dismutase or anti-CD36 antibody reduced foam cell formation and cholesterol efflux. Mice deficient in double genes of low-density lipoprotein receptor and low-density lipoprotein receptor-related protein (LRP), and mice deficient in a single gene of LRP8, the only LRP phenotype expressed in platelets, showed reduced leukocyte rolling and decreased platelet aggregation and thrombus formation in response to HNP stimulation.

CONCLUSIONS

HNPs exert proatherosclerotic properties that appear to be mediated through LRP8 signaling pathways, suggesting an important role for HNPs in the development of inflammatory cardiovascular diseases.

Dancing with the sterols: critical roles for ABCG1, ABCA1, miRNAs, and nuclear and cell surface receptors in controlling cellular sterol homeostasis

ATP binding cassette (ABC) transporters represent a large and diverse family of proteins that transport specific substrates across a membrane. The importance of these transporters is illustrated by the finding that inactivating mutations within 17 different family members are known to lead to specific human diseases. Clinical data from humans and/or studies with mice lacking functional transporters indicate that ABCA1, ABCG1, ABCG4, ABCG5 and ABCG8 are involved in cholesterol and/or phospholipid transport. This review discusses the multiple mechanisms that control cellular sterol homeostasis, including the roles of microRNAs, nuclear and cell surface receptors and ABC transporters, with particular emphasis on recent findings that have provided insights into the role(s) of ABCG1. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).

Platelet proteome in healthy volunteers who smoke

Smoking accelerates atherosclerosis and is a well-known risk factor for acute cardiovascular complications; however, the mechanisms of these effects have not been completely clarified. Recently developed proteomic approaches may offer new clues when combined with well-established functional tests. Platelet proteome of healthy smokers and non-smokers was resolved by two-dimensional difference gel electrophoresis, compared by Decyder software and identified by mass spectrometry analysis (nano-LC-MS/MS). In smokers, three proteins (Factor XIII-A subunit, platelet glycoprotein IIb and beta-actin) were significantly up-regulated, whereas WDR1 protein and chaperonine HSP60 were down-regulated. Furthermore, the highest scored network derived by Ingenuity Pathway Analysis using the modulated proteins as input showed the involvement of several proteins to be related to inflammation and apoptosis. Platelet function tests and the levels of markers of platelet and leukocyte activation were not different in smokers vs. non-smoker subjects. The platelet proteomic approach confirms that cigarette smoking triggers several inflammatory reactions and may help clarify some of the molecular mechanisms of smoke effect on cellular systems relevant for vascular integrity and human health.

Impact of leukocyte count on mortality and bleeding in patients with myocardial infarction undergoing primary percutaneous coronary interventions: analysis from the Harmonizing Outcome with Revascularization and Stent in Acute Myocardial Infarction trial

BACKGROUND

The relationship between white blood cell count (WBCc) and mortality in patients with ST-segment-elevation acute myocardial infarction treated with percutaneous coronary intervention is poorly understood. Furthermore, whether there is a relationship between WBCc and risk of noncardiac mortality and bleeding after percutaneous coronary intervention is unknown.

METHODS AND RESULTS

The baseline WBCc was available in 3193 of 3345 patients (95.5%) who underwent percutaneous coronary intervention in the Harmonizing Outcome With Revascularization and Stent in Acute Myocardial Infarction (HORIZONS-AMI) trial. In a propensity-adjusted multivariable analysis, WBCc was an independent predictor of 1-year cardiac mortality (hazard ratio, 1.15; 95% confidence interval, 1.09 to 1.22), noncardiac mortality (hazard ratio, 1.19; 95% confidence interval, 1.10 to 1.29), and major bleeding (hazard ratio, 1.08; 95% confidence interval, 1.04 to 1.12). After adjustment for baseline creatinine phosphokinase levels and left ventricular ejection fraction, WBCc remained an independent predictor of 1-year all-cause mortality and cardiac mortality. In patients matched for baseline creatinine phosphokinase levels at hospital admission, the median peak creatinine phosphokinase level was significantly higher in patients with high WBCc (>11 000 per 1 mm(3)) compared with low WBCc (1851 U/L [range, 880-3307 U/L] versus 1241 U/L [range, 540 to 2,78], respectively; P<0.0001). In this subgroup of patients, WBCc was an independent correlate of peak creatinine phosphokinase level, and remained an independent predictor of 1-year mortality.

CONCLUSIONS

In patients with ST-segment-elevation acute myocardial infarction undergoing percutaneous coronary intervention, elevated baseline WBCc is an independent predictor of infarct size, as assessed by peak creatinine phosphokinase level, and of 1-year cardiac mortality, noncardiac mortality, and major bleeding.

Relationship between white blood cell count and in-hospital outcomes in acute coronary syndrome patients from the Middle East

We evaluated the relationship between admission white blood cell (WBC) count and in-hospital outcomes in acute coronary syndrome (ACS) patients from the Middle East. Data were analyzed from 7806 consecutive patients with ACS who were divided into 4 groups (G) according to their WBC count (× 10(9)/L; G1: < 6.00; G2: 6.00-9.99; G3: 10.00-11.99; G4: ≥ 12.00). After significant covariate adjustment, those in G4 were 68% more likely to have cardiogenic shock than those in G1 (95% confidence interval [CI]: 1.05-2.68; P = .030) and G2 (odds ratio [OR], 2.02; 95% CI: 1.51-2.71; P < .001). Those in G4 were 2.02 times (95% CI: 1.11-3.67; P = .021) and 65% (95% CI: 1.17-2.32; P = .004) more likely to die in hospital than those in G1 and G2, respectively. Admission WBC count is an independent risk factor for in-hospital cardiogenic shock and mortality, in Middle Eastern patients with ACS. Novel therapeutic agents targeting WBCs in patients with ACS may improve outcomes.