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

Relationship between a systemic inflammatory marker, plaque inflammation, and plaque characteristics determined by intravascular optical coherence tomography

OBJECTIVE

The purpose of this study was to evaluate the relationships between the peripheral white blood cell (WBC) count, local plaque fibrous cap macrophage density, and the morphological features and presence of thin-cap fibroatheromas (TCFA) identified by optical coherence tomography (OCT).

METHODS AND RESULTS

OCT was performed in patients undergoing catheterization. Images were analyzed using validated criteria for plaque characteristics. Baseline WBC count correlated with macrophage density (r=0.483, P<0.001). Both parameters were associated with lipid-rich plaque and correlated inversely with plaque fibrous cap thickness (r=-0.547 for macrophage density and -0.423 for WBC count, P<0.015). Plaques classified as TCFA had a higher median macrophage density than non-TCFA plaques (7.4 versus 4.99, P<0.001). Patients with TCFA had a higher WBC count compared with those without TCFA (11.0 versus 7.9, P=0.007). Receiver operator curves for WBC count, macrophage density, and these combined parameters for prediction of TCFA showed the area under the curves were 0.88, 0.91, and 0.97 (P<0.001), respectively.

CONCLUSION

This study provides the first in vivo data linking the peripheral WBC count, plaque fibrous cap macrophage density, and the characteristics and presence of TCFA. Macrophage density correlated with the WBC count, and both parameters independently and particularly in combination predict the presence of TCFA.

White blood cell count and mortality in the Baltimore Longitudinal Study of Aging

OBJECTIVES

We investigated the secular trend in white blood cell (WBC) count and the relationship between WBC count and mortality between 1958 and 2002.

BACKGROUND

The WBC count is a clinical marker of inflammation and a strong predictor of mortality. Limited data exist on the WBC count secular trend and the relationship between WBC and mortality.

METHODS

One thousand eighty-three women and 1,720 men were evaluated longitudinally in the Baltimore Longitudinal Study of Aging. Blood samples and medical information were collected at the study entry and every 2 years during follow-up visits. The WBC count and all-cause, cardiovascular, and cancer mortality were assessed.

RESULTS

A downward trend in WBC count was observed from 1958 to 2002. The secular downward trend was independent of age, gender, race, smoking, body mass index, and physical activity. The WBC count was nonlinearly associated with all-cause mortality and almost linearly associated with cardiovascular mortality. Participants with baseline WBC <3,500 cells/mm3 and WBC >6,000 cells/mm3 had higher mortality than those with 3,500 to 6,000 WBC/mm3. Within each WBC group, age-adjusted mortality rates declined in successive cohorts from the 1960s to the 1990s. Participants who died had higher WBC than those who survived, and the difference was statistically significant within 5 years before death.

CONCLUSIONS

Our study provides evidence for a secular downward trend in WBC count over the period from 1958 to 2002. Higher WBC counts are associated with higher mortality in successive cohorts. We found no evidence that the decline of age-specific mortality rates that occurred from 1960 to 2000 was attributable to a secular downward trend in WBC.

Association of peripheral total and differential leukocyte counts with metabolic syndrome and risk of ischemic cardiovascular diseases in patients with type 2 diabetes mellitus

BACKGROUND

There is increasing evidence that leukocytes play a central role in obesity, glucose intolerance, type 2 diabetes mellitus (T2DM), and cardiovascular diseases, but the role of differential leukocytes in metabolic syndrome (MetS) and atherosclerosis is largely unknown. The aim of this study was to examine the relationship between the component features of MetS and peripheral leukocyte counts and to explore whether leukocyte counts are associated with clustering of MetS and macrovascular diseases in patients with T2DM.

METHODS

1872 subjects with T2DM who enrolled in a diabetes disease management program were studied. The definition of MetS was modified from that outlined by the criteria of NCEP-ATP III. Areas under the receiver-operating characteristic curve and odds ratios at various intervals of the WBC counts were computed.

RESULTS

The peripheral total leukocyte, monocyte, and neutrophil cell counts are increased parallel to the clustering of components of MetS. When white cell counts were analyzed per quartile and as continuous variables after adjustment for age, sex, and other known risk factors with multiple regression analysis, peripheral total leukocyte, monocyte, neutrophils, and lymphocyte counts were independently and significantly associated with specific features of clustering of MetS and prevalence of ischemic cardiovascular diseases. Leukocyte counts, especially neutrophil/lymphocyte ratio, in addition with MetS is associated with the risk of ischemic cardiovascular diseases.

CONCLUSION

Our results indicate that differential leukocyte counts are associated with MetS and that peripheral leukocytes may play a role in the pathogenesis of macrovascular complications in patients with T2DM.

Heart rate and microinflammation in men: a relevant atherothrombotic link

OBJECTIVE AND BACKGROUND

To explore the possibility that increased resting heart rate (HR) is associated with a microinflammatory response. Such an association could explain, at least in part, the recently described worse cardiovascular prognosis in individuals with increased HR.

METHODS

Concentrations of fibrinogen and high-sensitivity C-reactive protein, as well as the absolute number of polymorphonuclear leucocytes, were analysed in a cohort of 4553 apparently healthy men and in those with atherothrombotic risk factors.

RESULTS

Following adjustment for age and body mass index, lipid profile and cardiovascular risk factors, a significant (p<0.001) difference was noted between individuals in the first quintile of HR (< or =58 beats/min) and those in the fifth quintile (> or =79 beats/min) regarding all the above-mentioned inflammatory biomarkers, the respective mean values being 7.38 and 8.11 micromol/l, 1.12 and 1.61 mg/l, and 4.23 and 4.74 x 10(9)/l.

CONCLUSIONS

Resting HR is associated with a microinflammatory response in apparently healthy men and in those with atherothrombotic risk factors. Sympathetic activation might be a common factor explaining such an association. If confirmed in additional studies, this association might be a relevant target for therapeutic manipulations.

Biomarkers of outcome from cardiovascular disease

PURPOSE OF REVIEW

Recognition of the fact that low-grade local and systemic inflammation accompanies all stages of atherogenesis has led to the identification of a number of novel biomarkers of cardiovascular risk. We highlight recent epidemiological and experimental evidence concerning four emerging biomarkers: C-reactive protein, interleukin-6, D-dimer and white blood cell count.

RECENT FINDINGS

Recent epidemiological and experimental data on C-reactive protein, the most extensively studied marker of systemic inflammation, produced in the liver in response to interleukin-6, has cast some doubt on its clinical utility and causal involvement in atherogenesis. However, a large number of studies still strongly support C-reactive protein as an independent predictor of future cardiovascular risk and a potent proatherogenic agent. Among all markers of inflammation studied to date, C-reactive protein seems the most suitable one for use in clinical practice. Regarding white blood cell count, recent studies focused on the differential leucocyte count in coronary-heart-disease risk assessment; neutrophil count represents the strongest predictor of incident coronary heart disease.

SUMMARY

Thus, screening for low-grade inflammation using several novel biomarkers might provide an important tool to identify individuals at increased risk who would benefit most from targeted preventive interventions.

2-(4-Chlorobenzyl)-3-hydroxy-7,8,9,10-tetrahydrobenzo[H]quinoline-4-carboxylic Acid (PSI-697): Identification of a Clinical Candidate from the Quinoline Salicylic Acid Series of P-Selectin Antagonists

P-selectin-PSGL-1 interaction causes rolling of leukocytes on the endothelial cell surface, which subsequently leads to firm adherence and leukocyte transmigration through the vessel wall into the surrounding tissues. P-selectin is upregulated on the surface of both platelets and endothelium in a variety of atherosclerosis-associated conditions. Consequently, inhibition of this interaction by means of a small molecule P-selectin antagonist is an attractive strategy for the treatment of atherosclerosis. High-throughput screening and subsequent analoging had led to the identification of compound 1 as the lead candidate. Herein, we report the continuation of this work and the discovery of a second-generation series, the tetrahydrobenzoquinoline salicylic acids. These compounds have improved pharmacokinetic properties, and a number of them have shown oral efficacy in mouse and rat models of atherogenesis and vascular injury. The lead 31 (PSI-697), is currently in clinical development for the treatment of atherothrombotic vascular events.

Inhibition of tissue factor expression by hydroxyurea in polymorphonuclear leukocytes from patients with myeloproliferative disorders: a new effect for an old drug?

BACKGROUND

Polymorphonuclear leukocytes (PMN) from healthy subjects can produce and store tissue factor (TF), which is expressed on PMN surface upon in vitro stimulation with P-selectin.

RESULTS

We report here that platelets and PMN from 12 patients with myeloproliferative disorders (MPD) (six with polycythemia vera, six with essential thrombocythemia) show up regulation of P-selectin and TF, respectively, in the absence of any in vitro challenge. The number of circulating mixed platelet-PMN aggregates was also increased. PMN TF expression as well as mixed platelet-PMN aggregates, but not platelet P-selectin, were significantly reduced in six MPD patients after treatment with hydroxyurea (HU). In vitro studies performed on PMN separated from healthy donors confirmed HU effects (0-1400 microm). HU prevented both P-selectin-induced TF expression and mixed cell aggregate formation. The inhibitory effect of HU was specific for P-selectin-induced PMN activation, as it did not affect formyl-methionyl-leucyl-phenylalanine-induced PMN TF expression.

CONCLUSIONS

In MPD patients, platelet P-selectin-mediated TF expression on circulating PMN may play a role in thrombus formation and represents a novel target for the antithrombotic activity of HU.

Leukocytosis is a risk factor for thrombosis in essential thrombocythemia: interaction with treatment, standard risk factors, and Jak2 mutation status

Leukocytes contribute to the pathogenesis of thrombosis in essential thrombocythemia (ET) through recently discovered mechanisms of activation and interaction with platelets and endothelial cells. To evaluate whether an increased leukocyte count was associated with thrombosis and whether this effect can be modulated by therapy, we analyzed the clinical course of 439 patients with ET followed at the Ospedali Riuniti di Bergamo. The strength of the association was measured at diagnosis or before thrombotic events by multivariable analyses carried out using data at baseline as well as time-varying covariates. The results showed that (1) an increased leukocyte count at diagnosis was associated with thrombosis during follow-up (“baseline analysis,” relative risk [RR] 2.3, 95% confidence interval [CI] 1.4-3.9, P = .001); (2) hydroxyurea (HU) lowered leukocytosis and reduced the strength of the association between leukocytosis and thrombosis (“time-dependent analysis,” RR 1.6, 95% CI 0.9-2.0, not significant [NS]); (3) the association of leukocytosis and thrombosis was more evident in untreated low-risk patients (RR 2.7, 95% CI 1.2-6.4, P = .01) compared with HU-treated high-risk patients (RR 1.6, 95% CI 0.8-3.2, NS); and (4) the presence of JAK2 V617F was not identified as a risk factor for thrombosis during follow-up despite a significant association between the mutation and leukocytosis. We suggest validation of these findings in prospective clinical studies.

Leukocytosis as a major thrombotic risk factor in patients with polycythemia vera

In polycythemia vera, vascular risk assessment is based on age and thrombotic history, while the role of other potential predictors of this risk is still uncertain. Thus, we exploited the large database collected by the observational study of the European Collaboration on Low-Dose Aspirin in Polycythemia Vera (ECLAP) to investigate the association of hematologic variables and cardiovascular risk factors with the thrombotic risk. Among 1638 polycythemic patients followed for 2.7 +/- 1.3 years, there were 205 thromboses. Subjects with hypertension had a mild nonsignificant increase in the risk of arterial thrombosis, while this risk was significantly increased by smoking (hazard ratio [HR], 1.90; 95% confidence interval [CI], 1.15-3.14; P = .012). The time-dependent analysis adjusted for potential confounders showed that patients with a white blood cell count above 15 x 10(9)/L, compared with those with a white blood cell count below 10 x 10(9)/L, had a significant increase in the risk of thrombosis (HR, 1.71; 95% CI, 1.10-2.65; P = .017), mainly deriving from an increased risk of myocardial infarction (HR, 2.84; 95% CI, 1.25-6.46; P = .013). Thus, leukocyte count may help in defining the vascular risk of polycythemic subjects.

Oral Temperature in Daily Life. A New Look in the Era of Microinflammation

It has been repeatedly shown that apparently healthy individuals and those with atherothrombotic risk factors harbor a low grade subclinical internal inflammation (microinflammation). This low grade acute phase response is relevant for the presence of atherothrombosis and future vascular events. Since these events are associated with a febrile response, we thought that it is relevant to clarify whether the microinflammatory response has an influence on the oral temperature. Included were 2,340 men and 1,280 women in whom the white blood cell count (WBCC) and differential, as well as the erythrocyte sedimentation rate (ESR), quantitative fibrinogen and high sensitivity C-reactive protein (hs-CRP) were determined in addition to the oral temperature in quiescent conditions. There was no association between these inflammatory biomarkers, except from a weak association with the absolute number of polymorphonuclear leukocytes. This association could be, however, related to the stress of the examination itself. Thus, it is unlikely that the microinflammatory response in daily life is associated, to a significant degree, with an enhanced oral temperature. The results are relevant for the findings of elevated oral temperature during conditions of acute ischemia/infarction where the temperature is probably related to the event itself and not to the patient's background microinflammation.

Increased level of cardiorespiratory fitness blunts the inflammatory response in metabolic syndrome

OBJECTIVE

The presence of metabolic syndrome is associated with a higher degree of inflammation. We sought to assess whether the higher levels of cardiorespiratory fitness attenuate the levels of inflammation in people with metabolic syndrome.

RESEARCH DESIGN AND METHODS

We studied 449 consecutive asymptomatic men (47+/-7 years) who underwent a maximal treadmill exercise test according to the Bruce protocol. Cardiorespiratory fitness was divided into tertiles based on metabolic equivalents (METs). White blood cells (WBC) (x10(9) cells/L) count was used as marker of inflammation.

RESULTS

In our study population, 23% of the participants had the metabolic syndrome. The WBC count increased (p < 0.0001 for trend) with increasing number of risk factors for metabolic syndrome; however there was an inverse relationship (p < 0.0001 for trend) with increasing tertiles of fitness (6.47 cells x 10(9) cells/L for lowest tertile and 5.7 x 10(9) cells/L for highest tertile). Multiple linear regression analyses demonstrated that as compared to individuals with no MS risk factor, the WBC count remained significantly higher in men with metabolic syndrome in first tertile (regression coefficient: 1.2, 95% CI 0.4-2.0, p = 0.003) and second tertile (regression coefficient: 0.61, 95% CI 0.4-2.0, p = 0.02) of cardiorespiratory fitness, respectively. However, in the highest tertile of fitness no increase in level of WBC count was observed with increasing metabolic syndrome risk factors.

CONCLUSION

Our findings suggest that in people with metabolic syndrome an increased level of physical fitness might exert its beneficial effect via attenuating inflammation.

Leukocyte adhesion and thrombosis

PURPOSE OF THE REVIEW

The consequences of arterial thrombosis such as myocardial infarction, stroke and peripheral vascular occlusion are the leading causes of morbidity and mortality. A high leukocyte count and an elevation in inflammatory markers are identified as significant risk factors for thrombosis. Leukocytes form the front line in defense against infection and are the first cells arriving at the site of inflammation. This review summarizes the cellular and molecular mechanisms by which adherent leukocytes can induce a prothrombotic state.

RECENT FINDINGS

Circulating tissue factor has been recognized as a potential prothrombotic factor initiating thrombosis after vascular injury. The tissue factor is present on microvesicles originated from activated leukocytes. Leukocytes generate tissue factor containing microvesicles following stimulation with cytokines and following platelet adhesion via P-selectin. Additionally, activated leukocytes release several mediators, such as cathepsin G and elastase, which can activate both the coagulation cascade and platelets. Furthermore, new roles for leukocytes have been identified in vascular injury in sickle cell anemia, in vascular occlusion following the rupture of atherosclerotic plaque, and in thrombotic complications of myeloproliferative diseases.

SUMMARY

Leukocyte adhesion to endothelium and platelets plays an important role in the activation of the coagulation cascade. An excessive activation of leukocytes during the inflammatory process may induce a systemic procoagulant state. Elucidation of critical steps in activation of coagulation by leukocytes may offer a new therapeutic target for antithrombotic therapy based on blocking leukocyte adhesion.

Medical check-up findings characteristic of smokers: aimed at improving smoking cessation interventions by physicians

OBJECTIVE

The purpose of this study was to elucidate the medical check-up findings associated with smoking habit, which medical professionals, particularly physicians, should use for the promotion of quitting smoking.

METHODS

In 6,215 male and 1,627 female employees who participated in annual medical check-up, we compared the results of each test between smokers and nonsmokers.

RESULTS

Many results were significantly different between smokers and nonsmokers in both males and females. Among them, the hematocrit, leukocyte count, and levels of hemoglobin and triglyceride were significantly higher, the level of high-density lipoprotein cholesterol was significantly lower, and the frequencies of positive urinary occult blood and hearing loss were significantly higher in male smokers than in male nonsmokers. Furthermore, the hematocrit, leukocyte count, positive urinary occult blood, hearing loss, and levels of hemoglobin, triglyceride, and high-density lipoprotein cholesterol showed significant trends for male nonsmoker, and light, moderate, and heavy male smokers, that is, significant associations with larger numbers of cigarettes smoked per day.

CONCLUSION

Not only polycythemia and low high-density lipoprotein cholesterol level but also high leukocyte count, hearing loss, positive urinary occult blood, and high triglyceride level are smoking-related abnormal findings. In the medical check-up, medical professionals should inform smokers of these data and encourage them to quit smoking.

Preprocedural Levels of C-Reactive Protein and Leukocyte Counts Predict 9-Month Mortality After Coronary Angioplasty for the Treatment of Unprotected Left Main Coronary Artery Stenosis

Background— An accurate preprocedural risk stratification scheme for patients with unprotected left main coronary artery (ULMCA) stenosis who are undergoing coronary stenting is lacking. We examined the predictive value of preprocedural levels of C-reactive protein (CRP), fibrinogen, and leukocyte counts with respect to 9-month clinical outcomes after stenting of the ULMCA stenosis.

Methods and Results— Levels of CRP, fibrinogen, and leukocyte count were prospectively measured in 83 patients undergoing stenting of the ULMCA. A drug-eluting stent was used in 42 patients, and a bare metal stent was used in 41. The end point of the study was death and the combination of death and myocardial infarction (MI). By the 9-month follow-up, there were 11 deaths (13%), 7 MIs (8%), and 16 target lesion revascularizations (19%). Death and death/MI occurred in 19% and 31%, respectively, of 59 patients with high serum levels of CRP (>3 mg/L) but in none of 24 patients with normal CRP levels (for death, P =0.02; for death/MI, P =0.006). In multivariate analysis, the highest tertiles of CRP level ( P =0.028) and leukocyte count ( P =0.002) were the only independent predictors of death. The highest tertiles of CRP level ( P =0.002) and leukocyte count ( P =0.002) and acute coronary syndromes ( P =0.05) were the only independent predictors of the combined end point death/MI.

Conclusions— Elevated preprocedural levels of CRP indicate an increased risk of death and death/MI after ULMCA stenting. Inflammatory risk assessment in patients with ULMCA stenosis may be useful for selecting patients for percutaneous coronary interventions with very low risk.

Relationship of monocyte count and peripheral arterial disease: results from the National Health and Nutrition Examination Survey 1999-2002

BACKGROUND

Although white blood cell (WBC) count has been consistently associated with cardiovascular end points, little information is available on the independent contribution of specific white blood cell types. The objective of this study is to assess the independent association of WBC types and other inflammatory markers with the presence of reduced ankle-brachial blood pressure index (ABI), a marker of subclinical peripheral arterial disease (PAD).

METHODS & RESULTS

Cross-sectional study in 3949 individuals > or =40 years of age without known cardiovascular disease who participated in the 1999 to 2002 National Health and Nutrition Examination Survey (NHANES). PAD was defined as an ABI <0.9 in at least 1 leg. After adjustment for traditional cardiovascular risk factors, the odds ratios of PAD comparing the highest to the lowest quartiles were 2.24 (95% confidence interval 1.24 to 4.04) for monocytes, 1.74 (0.87 to 3.45) for neutrophils, 2.53 (1.62 to 3.96) for C-reactive protein, and 2.68 (1.03 to 6.94) for fibrinogen. When WBC types and inflammatory markers were simultaneously included in the full model, the corresponding odds ratios were 1.91 (95% confidence interval 1.06 to 3.42) for monocytes, 1.15 (0.49 to 2.69) for neutrophils, 1.37 (0.75 to 2.49) for C-reactive protein, and 2.21 (0.88 to 5.57) for fibrinogen.

CONCLUSIONS

Monocytes were the only WBC type significantly and independently associated with PAD in a representative sample of the U.S. population after adjustment for other inflammatory markers. These findings reflect the potential role of circulating monocyte counts as markers of atherosclerosis.