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

Elevated Leukocyte Count and Platelet-Derived Thrombogenicity Measured Using the Total Thrombus-Formation Analysis System in Patients with ST-Segment Elevation Myocardial Infarction

AIMS

High platelet-derived thrombogenicity during the acute phase of ST-segment elevation myocardial infarction (STEMI) is associated with poor outcomes; however, the associated factors remain unclear. This study aimed to examine whether acute inflammatory response after STEMI affects platelet-derived thrombogenicity.

METHODS

This retrospective observational single-center study included 150 patients with STEMI who were assessed for platelet-derived thrombogenicity during the acute phase. Platelet-derived thrombogenicity was assessed using the area under the flow-pressure curve for platelet chip (PL-AUC), which was measured using the total thrombus-formation analysis system (T-TAS). The peak leukocyte count was evaluated as an acute inflammatory response after STEMI. The patients were divided into two groups: the highest quartile of the peak leukocyte count and the other three quartiles combined.

RESULTS

Patients with a high peak leukocyte count (＞15,222/mm3; n=37) had a higher PL-AUC upon admission (420 [386-457] vs. 385 [292-428], p=0.0018), higher PL-AUC during primary percutaneous coronary intervention (PPCI) (155 [76-229] vs. 96 [29-170], p=0.0065), a higher peak creatine kinase level (4200±2486 vs. 2373±1997, p＜0.0001), and higher PL-AUC 2 weeks after STEMI (119 [61-197] vs. 88 [46-122], p=0.048) than those with a low peak leukocyte count (≤ 15,222/mm3; n=113). The peak leukocyte count after STEMI positively correlated with PL-AUC during primary PPCI (r=0.37, p＜0.0001). A multivariable regression analysis showed the peak leukocyte count to be an independent factor for PL-AUC during PPCI (β=0.26, p=0.0065).

CONCLUSIONS

An elevated leukocyte count is associated with high T-TAS-based platelet-derived thrombogenicity during the acute phase of STEMI.

Monocyte Single-Cell Multimodal Profiling in Cardiovascular Disease Risk States

BACKGROUND

Monocytes are a critical innate immune system cell type that serves homeostatic and immunoregulatory functions. They have been identified historically by the cell surface expression of CD14 and CD16. However, recent single-cell studies have revealed that they are much more heterogeneous than previously realized.

METHODS

We utilized cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) and single-cell RNA sequencing to describe the comprehensive transcriptional and phenotypic landscape of 437 126 monocytes.

RESULTS

This high-dimensional multimodal approach identified vast phenotypic diversity and functionally distinct subsets, including IFN-responsive, MHCIIhi (major histocompatibility complex class II), monocyte-platelet aggregates, as well as nonclassical, and several subpopulations of classical monocytes. Using flow cytometry, we validated the existence of MHCII+CD275+ MHCIIhi, CD42b+ monocyte-platelet aggregates, CD16+CD99- nonclassical monocytes, and CD99+ classical monocytes. Each subpopulation exhibited unique characteristics, developmental trajectories, transcriptional regulation, and tissue distribution. In addition, alterations associated with cardiovascular disease risk factors, including race, smoking, and hyperlipidemia were identified. Moreover, the effect of hyperlipidemia was recapitulated in mouse models of elevated cholesterol.

CONCLUSIONS

This integrative and cross-species comparative analysis provides a new perspective on the comparison of alterations in monocytes in pathological conditions and offers insights into monocyte-driven mechanisms in cardiovascular disease and the potential for monocyte subpopulation targeted therapies.

Skin autofluorescence, a measure for accumulation of advanced glycation end products, positively associates with blood neutrophil and monocyte counts in the general population, and particularly in men with prediabetes

BACKGROUND AND AIMS

Previous studies have shown that skin autofluorescence (SAF), measured with an advanced glycation end product (AGE) reader, estimates the accumulation of AGEs in tissues. SAF is predictive of incident type 2 diabetes, cardiovascular disease (CVD), and CV mortality in the general population. Studies in diabetic mice have shown that activation of the receptor for AGEs in hematopoietic progenitor cells increases blood neutrophils and monocytes, impairing atherosclerosis regression. We asked whether SAF is associated with blood neutrophil and monocyte counts in the general population, and whether this was moderated by prediabetes, diabetes, and sex.

METHODS

We examined the associations between SAF and blood neutrophil/monocyte counts in participants of the Lifelines cohort (n = 58,923: n = 24,382 men, and n = 34,541 women), a prospective population-based cohort from the North of the Netherlands, employing multivariable regression analyses.

RESULTS

SAF positively associated with blood neutrophil and monocyte counts in the whole cohort. The positive association between SAF and monocyte, but not neutrophil, counts was moderated by prediabetes and diabetes. Positive associations between SAF and blood neutrophil and monocyte counts were moderated by male sex. Moreover, three-way interaction analyses revealed that the positive associations between SAF and neutrophil and monocyte counts were moderated by prediabetes, but not diabetes, in male sex.

CONCLUSIONS

SAF is positively associated with blood neutrophil and monocyte counts in the general population, especially in men with prediabetes. This may contribute to the increased CV risk in men with prediabetes.

Molecular circadian clock disruption in the leukocytes of individuals with type 2 diabetes and overweight, and its relationship with leukocyte-endothelial interactions

AIMS/HYPOTHESIS

Alterations in circadian rhythms increase the likelihood of developing type 2 diabetes and CVD. Circadian rhythms are controlled by several core clock genes, which are expressed in nearly every cell, including immune cells. Immune cells are key players in the pathophysiology of type 2 diabetes, and participate in the atherosclerotic process that underlies cardiovascular risk in these patients. The role of the core clock in the leukocytes of people with type 2 diabetes and the inflammatory process associated with it are unknown. We aimed to evaluate whether the molecular clock system is impaired in the leukocytes of type 2 diabetes patients and to explore the mechanism by which this alteration leads to an increased cardiovascular risk in this population.

METHODS

This is an observational cross-sectional study performed in 25 participants with type 2 diabetes and 28 healthy control participants. Clinical and biochemical parameters were obtained. Peripheral blood leukocytes were isolated using magnetic bead technology. RNA and protein lysates were obtained to assess clock-related gene transcript and protein levels using real-time PCR and western blot, respectively. Luminex XMAP technology was used to assess levels of inflammatory markers. Leukocyte-endothelial interaction assays were performed by perfusing participants' leukocytes or THP-1 cells (with/without CLK8) over a HUVEC monolayer in a parallel flow chamber using a dynamic adhesion system.

RESULTS

Participants with type 2 diabetes showed increased BMAL1 and NR1D1 mRNA levels and decreased protein levels of circadian locomotor output cycles kaput (CLOCK), cryptochrome 1 (CRY1), phosphorylated basic helix-loop-helix ARNT like 1 (p-BMAL1) and period circadian protein homologue 2 (PER2). Correlation studies revealed that these alterations in clock proteins were negatively associated with glucose, HbA1c, insulin and HOMA-IR levels and leukocyte cell counts. The leukocyte rolling velocity was reduced and rolling flux and adhesion were enhanced in individuals with type 2 diabetes compared with healthy participants. Interestingly, inhibition of CLOCK/BMAL1 activity in leukocytes using the CLOCK inhibitor CLK8 mimicked the effects of type 2 diabetes on leukocyte-endothelial interactions.

CONCLUSIONS/INTERPRETATION

Our study demonstrates alterations in the molecular clock system in leukocytes of individuals with type 2 diabetes, manifested in increased mRNA levels and decreased protein levels of the core clock machinery. These alterations correlated with the impaired metabolic and proinflammatory profile of the participants with type 2 diabetes. Our findings support a causal role for decreased CLOCK/BMAL1 activity in the increased level of leukocyte-endothelial interactions. Overall, our data suggest that alterations in core clock proteins accelerate the inflammatory process, which may ultimately precipitate the onset of CVD in patients with type 2 diabetes.

Associations of systemic inflammatory regulators with CKD and kidney function: evidence from the bidirectional mendelian randomization study

BACKGROUND

Previous observational studies have reported that systemic inflammatory regulators are related to the development of chronic kidney disease (CKD); however, whether these associations are causal remains unclear. The current study aimed to investigate the potential causal relationships between systemic inflammatory regulators and CKD and kidney function.

METHOD

We performed bidirectional two-sample Mendelian randomization (MR) analyses to infer the underlying causal associations between 41 systemic inflammatory regulators and CKD and kidney function. The inverse-variance weighting (IVW) test was used as the primary analysis method. In addition, sensitivity analyses were executed via the Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) test and the weighted median test.

RESULTS

The findings revealed 12 suggestive associations between 11 genetically predicted systemic inflammatory regulators and CKD or kidney function in the forward analyses, including 4 for CKD, 3 for blood urea nitrogen (BUN), 4 for eGFRcrea and 1 for eGFRcys. In the other direction, we identified 6 significant causal associations, including CKD with granulocyte-colony stimulating factor (GCSF) (IVW β = 0.145; 95% CI, 0.042 to 0.248; P = 0.006), CKD with stem cell factor (SCF) (IVW β = 0.228; 95% CI, 0.133 to 0.323; P = 2.40 × 10- 6), eGFRcrea with SCF (IVW β =-2.90; 95% CI, -3.934 to -1.867; P = 3.76 × 10- 8), eGFRcys with GCSF (IVW β =-1.382; 95% CI, -2.404 to -0.361; P = 0.008), eGFRcys with interferon gamma (IFNg) (IVW β =-1.339; 95% CI, -2.313 to -0.366; P = 0.007) and eGFRcys with vascular endothelial growth factor (VEGF) (IVW β =-1.709; 95% CI, -2.720 to -0.699; P = 9.13 × 10- 4).

CONCLUSIONS

Our findings support causal links between systemic inflammatory regulators and CKD or kidney function both in the forward and reverse MR analyses.

Circadian Effects on Vascular Immunopathologies

Circadian rhythms exert a profound impact on most aspects of mammalian physiology, including the immune and cardiovascular systems. Leukocytes engage in time-of-day-dependent interactions with the vasculature, facilitating the emigration to and the immune surveillance of tissues. This review provides an overview of circadian control of immune-vascular interactions in both the steady state and cardiovascular diseases such as atherosclerosis and infarction. Circadian rhythms impact both the immune and vascular facets of these interactions, primarily through the regulation of chemoattractant and adhesion molecules on immune and endothelial cells. Misaligned light conditions disrupt this rhythm, generally exacerbating atherosclerosis and infarction. In cardiovascular diseases, distinct circadian clock genes, while functioning as part of an integrated circadian system, can have proinflammatory or anti-inflammatory effects on these immune-vascular interactions. Here, we discuss the mechanisms and relevance of circadian rhythms in vascular immunopathologies.

Residual risks and evolving atherosclerotic plaques

Atherosclerotic disease of the coronary and carotid arteries is the primary global cause of significant mortality and morbidity. The chronic occlusive diseases have changed the epidemiological landscape of health problems both in developed and the developing countries. Despite the enormous benefit of advanced revascularization techniques, use of statins, and successful attempts of targeting modifiable risk factors, like smoking and exercise in the last four decades, there is still a definite "residual risk" in the population, as evidenced by many prevalent and new cases every year. Here, we highlight the burden of the atherosclerotic diseases and provide substantial clinical evidence of the residual risks in these diseases despite advanced management settings, with emphasis on strokes and cardiovascular risks. We critically discussed the concepts and potential underlying mechanisms of the evolving atherosclerotic plaques in the coronary and carotid arteries. This has changed our understanding of the plaque biology, the progression of unstable vs stable plaques, and the evolution of plaque prior to the occurrence of a major adverse atherothrombotic event. This has been facilitated using intravascular ultrasound, optical coherence tomography, and near-infrared spectroscopy in the clinical settings to achieve surrogate end points. These techniques are now providing exquisite information on plaque size, composition, lipid volume, fibrous cap thickness and other features that were previously not possible with conventional angiography.

The Neutrophil-to-Lymphocyte Ratio as a Predictor of Postoperative Outcomes in Patients Undergoing Coronary Artery Bypass Grafting

Background

The neutrophil-to-lymphocyte ratio (NLR) has been suggested as a novel predictive marker of cardiovascular disease. However, its prognostic role in patients undergoing coronary artery bypass grafting (CABG) is unclear. This study aimed to determine the association between the preoperative NLR and early mortality in patients undergoing CABG.

Methods

Cardiac surgery was performed in 2,504 patients at Seoul St. Mary's Hospital from January 2010 to December 2021. This study retrospectively reviewed 920 patients who underwent isolated CABG, excluding those for whom the preoperative NLR was unavailable. The primary endpoints were the 30- and 90-day mortality after isolated CABG. Risk factor analysis was performed using logistic regression analysis. Based on the optimal cut-off value of preoperative NLR on the receiver operating characteristic curve, high and low NLR groups were compared.

Results

The 30- and 90-day mortality rates were 3.8% (n=35) and 7.0% (n=64), respectively. In the multivariable analysis, preoperative NLR was significantly associated with 30-day mortality (odds ratio [OR], 1.28; 95% confidence interval [CI], 1.17-1.39; p<0.001) and 90-day mortality (OR, 1.17; 95% CI, 1.07-1.28; p<0.001). The optimal cut-off value of the preoperative NLR was 3.4. Compared to the low NLR group (<3.4), the high NLR group (≥3.4) showed higher 30- and 90-day mortality rates (1.4% vs. 12.1%, p<0.001; 2.8% vs. 21.3%, p<0.001, respectively).

Conclusion

Preoperative NLR was strongly associated with early mortality after isolated CABG, especially in patients with a high preoperative NLR (≥3.4). Further studies with larger cohorts are necessary to validate these results.

Neutrophil dynamics and inflammaging in acute ischemic stroke: A transcriptomic review

Stroke is among the leading causes of death and disability worldwide. Restoring blood flow through recanalization is currently the only acute treatment for cerebral ischemia. Unfortunately, many patients that achieve a complete recanalization fail to regain functional independence. Recent studies indicate that activation of peripheral immune cells, particularly neutrophils, may contribute to microcirculatory failure and futile recanalization. Stroke primarily affects the elderly population, and mortality after endovascular therapies is associated with advanced age. Previous analyses of differential gene expression across injury status and age identify ischemic stroke as a complex age-related disease. It also suggests robust interactions between stroke injury, aging, and inflammation on a cellular and molecular level. Understanding such interactions is crucial in developing effective protective treatments. The global stroke burden will continue to increase with a rapidly aging human population. Unfortunately, the mechanisms of age-dependent vulnerability are poorly defined. In this review, we will discuss how neutrophil-specific gene expression patterns may contribute to poor treatment responses in stroke patients. We will also discuss age-related transcriptional changes that may contribute to poor clinical outcomes and greater susceptibility to cerebrovascular diseases.

Neutrophil circadian rhythm is associated with different outcomes of acute kidney injury due to cholesterol crystal embolism

Cholesterol crystal (CC) embolism can cause acute tissue infarction and ischemic necrosis via triggering diffuse thrombotic angiopathy occluding arterioles and arteries. Neutrophils contribute to crystal-induced immunothrombosis as well as to ischemic necrosis-related necroinflammation. We speculated that CC embolism-induced acute kidney injury (AKI) would be circadian rhythm-dependent and associated with cyclic differences in neutrophil function. Injection of CC into the left kidney induced thrombotic angiopathy progressing starting as early as 3 h after CC injection followed by a progressive ischemic cortical necrosis and AKI at 24 h. In C57BL/6J mice, circulating CD11b+Ly6G+ neutrophils were higher during the day phase [Zeitgeber time (ZT) 0–12] compared to the dark phase (ZT12-24). In the time frame of thrombus formation at ZT13, more neutrophils were recruited into the injured kidney 24 h later compared to CC embolism at ZT5. This effect was associated with an increased circulating number of CXCR2+ neutrophils as well as an upregulated kidney adhesion molecule and chemokine expression. These findings were associated with a significant increase in kidney necrosis, and endothelial injury at ZT13. Thus, the time of day has an effect also on CC embolism-related AKI in association with the circadian rhythm of neutrophil recruitment.

Immune and Inflammatory Networks in Myocardial Infarction: Current Research and Its Potential Implications for the Clinic

Despite recent scientific and technological advances, myocardial infarction (MI) still represents a major global health problem, leading to high morbidity and mortality worldwide. During the post-MI wound healing process, dysregulated immune inflammatory pathways and failure to resolve inflammation are associated with maladaptive left ventricular remodeling, progressive heart failure, and eventually poor outcomes. Given the roles of immune cells in the host response against tissue injury, understanding the involved cellular subsets, sources, and functions is essential for discovering novel therapeutic strategies that preserve the protective immune system and promote optimal healing. This review discusses the cellular effectors and molecular signals across multi-organ systems, which regulate the inflammatory and reparative responses after MI. Additionally, we summarize the recent clinical and preclinical data that propel conceptual revolutions in cardiovascular immunotherapy.

The Current Status of Research on High-Density Lipoproteins (HDL): A Paradigm Shift from HDL Quantity to HDL Quality and HDL Functionality

The quantity of high-density lipoproteins (HDL) is represented as the serum HDL-C concentration (mg/dL), while the HDL quality manifests as the diverse features of protein and lipid content, extent of oxidation, and extent of glycation. The HDL functionality represents several performance metrics of HDL, such as antioxidant, anti-inflammatory, and cholesterol efflux activities. The quantity and quality of HDL can change during one's lifetime, depending on infection, disease, and lifestyle, such as dietary habits, exercise, and smoking. The quantity of HDL can change according to age and gender, such as puberty, middle-aged symptoms, climacteric, and the menopause. HDL-C can decrease during disease states, such as acute infection, chronic inflammation, and autoimmune disease, while it can be increased by regular aerobic exercise and healthy food consumption. Generally, high HDL-C at the normal level is associated with good HDL quality and functionality. Nevertheless, high HDL quantity is not always accompanied by good HDL quality or functionality. The HDL quality concerns the morphology of the HDL, such as particle size, shape, and number. The HDL quality also depends on the composition of the HDL, such as apolipoproteins (apoA-I, apoA-II, apoC-III, serum amyloid A, and α-synuclein), cholesterol, and triglyceride. The HDL quality is also associated with the extent of HDL modification, such as glycation and oxidation, resulting in the multimerization of apoA-I, and the aggregation leads to amyloidogenesis. The HDL quality frequently determines the HDL functionality, which depends on the attached antioxidant enzyme activity, such as the paraoxonase and cholesterol efflux activity. Conventional HDL functionality is regression, the removal of cholesterol from atherosclerotic lesions, and the removal of oxidized species in low-density lipoproteins (LDL). Recently, HDL functionality was reported to expand the removal of β-amyloid plaque and inhibit α-synuclein aggregation in the brain to attenuate Alzheimer's disease and Parkinson's disease, respectively. More recently, HDL functionality has been associated with the susceptibility and recovery ability of coronavirus disease 2019 (COVID-19) by inhibiting the activity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The appearance of dysfunctional HDL is frequently associated with many acute infectious diseases and chronic aging-related diseases. An HDL can be a suitable biomarker to diagnose many diseases and their progression by monitoring the changes in its quantity and quality in terms of the antioxidant and anti-inflammatory abilities. An HDL can be a protein drug used for the removal of plaque and as a delivery vehicle for non-soluble drugs and genes. A dysfunctional HDL has poor HDL quality, such as a lower apoA-I content, lower antioxidant ability, smaller size, and ambiguous shape. The current review analyzes the recent advances in HDL quantity, quality, and functionality, depending on the health and disease state during one's lifetime.

Bone marrow endothelial dysfunction promotes myeloid cell expansion in cardiovascular disease

Abnormal hematopoiesis advances cardiovascular disease by generating excess inflammatory leukocytes that attack the arteries and the heart. The bone marrow niche regulates hematopoietic stem cell proliferation and hence the systemic leukocyte pool, but whether cardiovascular disease affects the hematopoietic organ's microvasculature is unknown. Here we show that hypertension, atherosclerosis and myocardial infarction (MI) instigate endothelial dysfunction, leakage, vascular fibrosis and angiogenesis in the bone marrow, altogether leading to overproduction of inflammatory myeloid cells and systemic leukocytosis. Limiting angiogenesis with endothelial deletion of Vegfr2 (encoding vascular endothelial growth factor (VEGF) receptor 2) curbed emergency hematopoiesis after MI. We noted that bone marrow endothelial cells assumed inflammatory transcriptional phenotypes in all examined stages of cardiovascular disease. Endothelial deletion of Il6 or Vcan (encoding versican), genes shown to be highly expressed in mice with atherosclerosis or MI, reduced hematopoiesis and systemic myeloid cell numbers in these conditions. Our findings establish that cardiovascular disease remodels the vascular bone marrow niche, stimulating hematopoiesis and production of inflammatory leukocytes.

Hepatocyte-specific glucose-6-phosphatase deficiency disturbs platelet aggregation and decreases blood monocytes upon fasting-induced hypoglycemia

OBJECTIVE

Glycogen storage disease type 1a (GSD Ia) is a rare inherited metabolic disorder caused by mutations in the glucose-6-phosphatase (G6PC1) gene. When untreated, GSD Ia leads to severe fasting-induced hypoglycemia. Although current intensive dietary management aims to prevent hypoglycemia, patients still experience hypoglycemic events. Poor glycemic control in GSD Ia is associated with hypertriglyceridemia, hepatocellular adenoma and carcinoma, and also with an increased bleeding tendency of unknown origin.

METHODS

To evaluate the effect of glycemic control on leukocyte levels and coagulation in GSD Ia, we employed hepatocyte-specific G6pc1 deficient (L-G6pc-/-) mice under fed or fasted conditions, to match good or poor glycemic control in GSD Ia, respectively.

RESULTS

We found that fasting-induced hypoglycemia in L-G6pc-/- mice decreased blood leukocytes, specifically proinflammatory Ly6Chi monocytes, compared to controls. Refeeding reversed this decrease. The decrease in Ly6Chi monocytes was accompanied by an increase in plasma corticosterone levels and was prevented by the glucocorticoid receptor antagonist mifepristone. Further, fasting-induced hypoglycemia in L-G6pc-/- mice prolonged bleeding time in the tail vein bleeding assay, with reversal by refeeding. This could not be explained by changes in coagulation factors V, VII, or VIII, or von Willebrand factor. While the prothrombin and activated partial thromboplastin time as well as total platelet counts were not affected by fasting-induced hypoglycemia in L-G6pc-/- mice, ADP-induced platelet aggregation was disturbed.

CONCLUSIONS

These studies reveal a relationship between fasting-induced hypoglycemia, decreased blood monocytes, and disturbed platelet aggregation in L-G6pc-/- mice. While disturbed platelet aggregation likely accounts for the bleeding phenotype in GSD Ia, elevated plasma corticosterone decreases the levels of proinflammatory monocytes. These studies highlight the necessity of maintaining good glycemic control in GSD Ia.

Stabilin-2 deficiency increases thrombotic burden and alters the composition of venous thrombi in a mouse model

BACKGROUND

Stabilin-2 is an endocytic scavenger receptor that mediates the clearance of glycosaminoglycans, phosphatidylserine-expressing cells, and the von Willebrand factor-factor VIII (FVIII) complex. In a genome-wide screening study, pathogenic loss-of-function variants in the human STAB2 gene associated with an increased incidence of unprovoked venous thromboembolism (VTE). However, the specific mechanism(s) by which stabilin-2 deficiency influences the pathogenesis of VTE is unknown.

OBJECTIVES

The aim of this study was to assess the influence of stabilin-2 on deep vein thrombosis (DVT) and to characterize the underlying prothrombotic phenotype of stabilin-2 deficiency in a mouse model.

METHODS

DVT was induced using the inferior vena cava (IVC) stenosis model in two independent cohorts (littermates and non-littermates) of wild-type (Stab2+/+ ) and stabilin-2 (Stab2-/- )-deficient mice. Thrombus structure and contents were quantified by immunohistochemistry. Plasma procoagulant activity was assessed and complete blood counts were performed.

RESULTS

Incidence of thrombus formation was not altered between Stab2+/+ and Stab2-/- mice. When thrombi were formed, Stab2-/- mice developed significantly larger thrombi than Stab2+/+ controls. Thrombi from Stab2-/- mice contained significantly more leukocytes and citrullinated histone H3 than Stab2+/+ thrombi. Stab2-/- mice had increased FVIII activity. Circulating levels of monocytes and granulocytes were significantly elevated in Stab2-/- mice, and Stab2-/- mice had elevated plasma cell-free DNA 24 hours post-IVC stenosis compared to their Stab2+/+ counterparts.

CONCLUSIONS

These data suggest that stabilin-2 deficiency associates with a prothrombotic phenotype involving elevated levels of neutrophil extracellular trap-releasing leukocytes coupled with endogenous procoagulant activity, resulting in larger and qualitatively distinct venous thrombi.

[Vascular inflammation underlies the development of atherothrombotic stroke]

Atherothrombotic stroke is the one of the most common subtypes of ischemic cerebral circulatory disorders, the cause of which is atherosclerosis of the major arteries of the brain or their branches. The results of recent studies have shown that the atherosclerotic process is based on an inflammatory process in the vascular wall that leads to the initiation of atherosclerosis, endothelial dysfunction, oxidative stress, and the redistribution of various protein components in the blood-brain barrier. As a result, the progression of the described conditions leads to the manifestation of clinical symptoms and the formation of an acute vascular event. Understanding of the molecular components underlying functional disorders and damages of the cerebral vessels gives the key to modern therapy strategies. It is forming the foundation for the adequate, pathogenetically reasonable drug correction. For such patients, it should be aimed at the normalization of cerebral and central hemodynamics and incorporate the mechanisms of neuroplasticity. The drug 2-ethyl-6-methyl-3-oxypyridine-succinate (mexidol) can be considered as one of the pathogenetically justified agents in complex drug therapy of brain ischemia.

Brown adipose tissue monocytes support tissue expansion

Monocytes are part of the mononuclear phagocytic system. Monocytes play a central role during inflammatory conditions and a better understanding of their dynamics might open therapeutic opportunities. In the present study, we focused on the characterization and impact of monocytes on brown adipose tissue (BAT) functions during tissue remodeling. Single-cell RNA sequencing analysis of BAT immune cells uncovered a large diversity in monocyte and macrophage populations. Fate-mapping experiments demonstrated that the BAT macrophage pool requires constant replenishment from monocytes. Using a genetic model of BAT expansion, we found that brown fat monocyte numbers were selectively increased in this scenario. This observation was confirmed using a CCR2-binding radiotracer and positron emission tomography. Importantly, in line with their tissue recruitment, blood monocyte counts were decreased while bone marrow hematopoiesis was not affected. Monocyte depletion prevented brown adipose tissue expansion and altered its architecture. Podoplanin engagement is strictly required for BAT expansion. Together, these data redefine the diversity of immune cells in the BAT and emphasize the role of monocyte recruitment for tissue remodeling.

Adipose tissue is composed of a number of adipocytes and a number of other cells including immune cells. Here the authors use single-cell sequencing of murine brown adipose tissue immune cells and describe multiple macrophage and monocyte subsets and show that monocytes contribute to brown adipose tissue expansion.

The Role of Acidosis in the Pathogenesis of Severe Forms of COVID-19

COVID-19 has specific characteristics that distinguish this disease from many other infections. We suggest that the pathogenesis of severe forms of COVID-19 can be associated with acidosis. This review article discusses several mechanisms potentially linking the damaging effects of COVID-19 with acidosis and shows the existence of a vicious cycle between the development of hypoxia and acidosis in COVID-19 patients. At the early stages of the disease, inflammation, difficulty in gas exchange in the lungs and thrombosis collectively contribute to the onset of acidosis. In accordance with the Verigo-Bohr effect, a decrease in blood pH leads to a decrease in oxygen saturation, which contributes to the exacerbation of acidosis and results in a deterioration of the patient's condition. A decrease in pH can also cause conformational changes in the S-protein of the virus and thus lead to a decrease in the affinity and avidity of protective antibodies. Hypoxia and acidosis lead to dysregulation of the immune system and multidirectional pro- and anti-inflammatory reactions, resulting in the development of a "cytokine storm". In this review, we highlight the potential importance of supporting normal blood pH as an approach to COVID-19 therapy.

Data-driven analysis of the kinetics of the JAK2V617F allele burden and blood cell counts during hydroxyurea treatment of patients with polycythemia vera, essential thrombocythemia, and primary myelofibrosis

BACKGROUND

Hydroxyurea (HU) treatment of patients with essential thrombocythemia (ET), polycythemia vera (PV), and primary myelofibrosis (PMF) (MPNs) normalizes elevated blood cell counts within weeks in the large majority of patients. Studies on the impact of HU upon the kinetics of the JAK2V617F allele burden, leukocyte, and platelet counts over time are scarce.

PURPOSE

Using data-driven analysis as a novel tool to model the kinetics of the JAK2V617F allele burden and blood cell counts over time during treatment with HU.

MATERIAL AND METHODS

Using serial measurements of JAK2V617F and correlation analysis of routine hematological values (the Hb-concentration, leukocyte count, platelet count, and lactic dehydrogenase), we present a detailed description and analysis of the kinetics of the JAK2V617F, leukocyte, and platelet counts and lactic dehydrogenase in 27 patients (PV = 18; ET = 7; PMF = 2), who were followed in the Danish randomized trial (DALIAH). To further analyze the JAK2V617F kinetics, we use a machine learning clustering algorithm to group the response patterns.

RESULTS

Response patterns were highly heterogeneous, with clustering resulting in 3 groups and 3 outliers. In the large majority of patients, HU treatment was initially associated with a modest decline in the JAK2V617F allele burden in concert with a decline in leukocyte and platelet counts. However, HU did not induce a sustained and continuous decrease in the JAK2V617F allele burden.

CONCLUSION

Using data-driven analysis of the JAK2V617F allele burden, leukocyte, and platelet kinetics during treatment with HU, we have shown that HU does not induce a sustained decrease in the JAK2V617F allele burden and neither induces sustained normalization of elevated cell counts in MPN patients. Our results may explain why MPN patients during treatment with HU still have a substantially increased risk of thrombosis.

Cholesterol efflux pathways, inflammation, and atherosclerosis

Plasma levels of high-density lipoprotein (HDL) inversely correlate with the incidence of cardiovascular diseases (CVD). The causal relationship between plasma HDL-cholesterol levels and CVD has been called into question by Mendelian randomization studies and the majority of clinical trials not showing any benefit of plasma HDL-cholesterol raising drugs on CVD. Nonetheless, recent Mendelian randomization studies including an increased number of CVD cases compared to earlier studies have confirmed that HDL-cholesterol levels and CVD are causally linked. Moreover, several studies in large population cohorts have shown that the cholesterol efflux capacity of HDL inversely correlates with CVD. Cholesterol efflux pathways exert anti-inflammatory and anti-atherogenic effects by suppressing proliferation of hematopoietic stem and progenitor cells, and inflammation and inflammasome activation in macrophages. Cholesterol efflux pathways also suppress the accumulation of cholesteryl esters in macrophages, i.e. macrophage foam cell formation. Recent single-cell RNASeq studies on atherosclerotic plaques have suggested that macrophage foam cells have lower expression of inflammatory genes than non-foam cells, probably reflecting liver X receptor activation, upregulation of ATP Binding Cassette A1 and G1 cholesterol transporters and suppression of inflammation. However, when these pathways are defective lesional foam cells may become pro-inflammatory.

Macrophage ontogeny and functional diversity in cardiometabolic diseases

Macrophages are the dominant immune cell types in the adipose tissue, the liver or the aortic wall and they were originally believed to mainly derived from monocytes to fuel tissue inflammation in cardiometabolic diseases. However, over the last decade the identification of tissue resident macrophages (trMacs) from embryonic origin in these metabolic tissues has provided a breakthrough in the field forcing to better comprehend macrophage diversity during pathological states. Infiltrated monocyte-derived macrophages (moMacs), similar to trMacs, adapt to the local metabolic environment that eventually shapes their functions. In this review, we will summarize the emerging versatility of macrophages in cardiometabolic diseases with a focus in the control of adipose tissue, liver and large vessels homeostasis.

Neutrophil extracellular traps induce thrombogenicity in severe carotid stenosis

Background

Severe carotid stenosis is a common cause of stroke. In addition, previous clinical studies revealed that patients symptomatic of carotid stenosis suffer from increased episodes of stroke compared with their asymptomatic counterparts. However, the mechanism underlying these differences in the recurrence of stroke remains unclear.

Objective

The present study aimed to evaluate the levels of neutrophil extracellular traps (NETs) in the plasma of patients with severe carotid stenosis and investigate whether NETs induced procoagulant activity (PCA) in severe carotid stenosis. The study also sought to investigate the interactions between platelets or endothelial cells (ECs) and NETs.

Methods

The levels of NETs in plasma were quantified using enzyme‐linked immunosorbent assay (ELISA). In addition, NETting neutrophils and neutrophil‐platelet aggregates were detected through flow cytometry. On the other hand, the morphology of NETs formation and endothelial cells were analyzed through confocal microscopy. Finally, the procoagulant activity (PCA) of NETs and endothelial cells were assessed through ELISA and fibrin formation.

Results

Patients with symptomatic carotid stenosis patients had significantly higher levels of NETs markers compared with their asymptomatic counterparts and healthy subjects. In addition, increased levels of neutrophil‐platelet aggregates induced the generation of NETs in patients with symptomatic carotid stenosis. Moreover, NETs contributed to PCA through tissue factor (TF), in patients with carotid stenosis. Furthermore, NETs disrupted the endothelial barrier and converted endothelial cells (ECs) into PCA to enhance the PCA in patients with carotid stenosis.

Conclusions

The current study revealed differences in the levels of NETs in the plasma of symptomatic and asymptomatic patients suffering from carotid stenosis. The study also uncovered the interaction between NETs and thrombogenicity in carotid stenosis. Therefore, inhibiting NETs may be a potential biomarker and therapeutic target for recurring stroke in severe carotid stenosis.

Weighty choices: selecting optimal G-CSF doses for stem cell mobilization to optimize yield

There are limited data on the effect of donor body mass index (BMI) on peripheral blood stem cell (PBSC) mobilization response to granulocyte colony-stimulating factor (G-CSF), especially in unrelated donors. Obesity has been associated with persistent leukocytosis, elevated circulating progenitor cells, and enhanced stem cell mobilization. Therefore, we hypothesized that adequate collection of CD34+ cells may be achieved with lower doses (per kilogram of body weight) of G-CSF in donors with higher BMI compared with donors with lower BMI. Using the Center for International Blood and Marrow Transplant Research database, we evaluated the impact of donor BMI on G-CSF-mobilized PBSC yield in healthy unrelated donors. We examined 20 884 PBSC donations collected at National Marrow Donor Program centers between 2006 and 2016. We found significantly higher collection yields in obese and severely obese donors compared with normal and overweight donors. An increase in average daily G-CSF dose was associated with an increase in stem cell yield in donors with normal or overweight BMI. In contrast, an increase in average daily G-CSF dose beyond 780 μg per day in obese and 900 μg per day in severely obese donors did not increase cell yield. Pain and toxicities were assessed at baseline, during G-CSF administration, and postcollection. Obesity was associated with higher levels of self-reported donation-related pain and toxicities in the pericollection and early postdonation recovery periods. This study suggests a maximum effective G-CSF dose for PBSC mobilization in obese and severely obese donors, beyond which higher doses of G-CSF add no increased yield.

Clinical and therapeutic features of acute cholecystitis in diabetic patients

The present study aimed to compare the clinical, paraclinical, intraoperative findings, and postoperative complications in acute cholecystitis in diabetic patients vs. non-diabetic patients. A 2-year retrospective study was performed on the patients who underwent emergency cholecystectomy for acute cholecystitis between 2017 and 2019 at the 4th Department of Surgery, Emergency University Hospital Bucharest. The diabetic subgroup numbered 46 eligible patients and the non-diabetic one 287 patients. Demographics, the severity of the clinical forms, biological variables (including white cell count, urea, creatinine, coagulation and liver function tests) comorbidity status, surgical approach, postoperative complications, and hospital stay were analyzed. Statistical analyses were performed to assess comparative results between the aforementioned data (SPSS V 13.0). The CCI and ASA risk classes were increased in the diabetic group, with 34.78% of patients having 3 or more associated comorbidities. No statistically significant associations were demonstrated between diabetes and the severity of the cholecystitis and risk for conversion. Postoperatively both minor complications such as surgical site infections and major cardiovascular events were more common in the diabetic subgroup (P=0.0254), well associated with the preoperative status and baseline cardiovascular comorbidities. Laparoscopic cholecystectomy is a safe procedure for diabetic patients, which can provide the best outcomes, by decreasing the risks of surgical wounds. Attentive perioperative care and good glycemic control must be provided to minimize the risk of complications.

The effects of CO2 pneumoperitoneum at different temperature and humidity on hemodynamic and respiratory parameters and postoperative pain in gynecological laparoscopic surgery: A prospective randomized controlled study

BACKGROUND

It is recommended to heat and humidity CO₂ in laparoscopic surgery to prevent postoperative pain and hypothermia but information about its effects on hemodynamic and respiratory parameters is limited. We aimed to investigate the effects of standard and heated-humidified CO₂ on hemodynamic and respiratory parameters, body temperature and pain in healthy patients.

METHODS

One hundred patients who underwent total laparoscopic hysterectomy for benign pathology were divided into two groups: Group CD (cold-dry) patients were administered standard CO₂, while Group HH (heated-humidified) patients were administered 95% humidified insufflation at 37 °C. Hemodynamic and respiratory parameters, body temperature, pain score and blood count parameters were recorded.

RESULTS

A total of 96 patients were included in the study, taken from the 100 patients. Group HH (n:47) had only higher systolic blood pressure at 75, mean blood pressure at 50 and 55 and a lower heart rate between 15 and 45 min (p:0.049, 0.037, 0.013 respectively). Pain score, morphine consumption, end-tidal CO₂ and arterial blood gas values were not different between the groups, with only body temperature from 40 min and minimum value being significantly higher (at a difference of 0.86-1.04 °C) in Group HH. Postoperative leukocyte, neutrophil and NLR (neutrophil-leukocyte ratio) were found to be higher in this group (p < 0.05).

CONCLUSION

It has been found that both standard and heated-humidified CO₂do not constitute a problem in terms of hemodynamic and respiratory parameters in healthy patients. The heated-humidified CO₂group had only a higher core body temperature and inflammatory response.

TRIAL REGISTRATION

NCT04508387.

The association between lipid levels and leukocyte count: A cross-sectional and longitudinal analysis of three large cohorts

Background

Relationships between dyslipidaemia and leukocyte counts have been investigated in several studies, demonstrating limited evidence of associations in humans. As such, studying a diverse range of cohorts will ensure evidence is robust. This study focused on investigating cross-sectional and longitudinal relationships in three large-scale cohorts.

Methods

The cross-sectional analysis included a total of 27,566 participants with valid data on lipid measures and leukocyte counts from three study cohorts: National Health and Nutrition Survey (NHANES), Korean National Health and Nutrition Survey (KNHANES) and Treating to New Targets (TNT) trial. The longitudinal analysis included 9323 participants with valid data on lipid measures and leukocyte counts at baseline and one year with statin treatment. Associations between lipid levels and leukocyte counts were analysed by multivariable linear regression and adjusted for basic demographic and cardiovascular risk factors.

Results

Cross-sectional data from NHANES demonstrated the association of lower high-density lipoprotein (HDL) cholesterol and higher triglycerides with higher leukocyte count (0.9% lower and 0.3% higher count per 10 mg/dL increase in HDL cholesterol and triglycerides respectively, both p < 0.001). Similar trends were found in TNT trial (both p < 0.001), but not in KNHANES. In the TNT trial, 10 mg/dL increase in triglycerides over one year was also associated with a 0.09 × 103/μL increase in leukocyte count over the same period.

Conclusions

The findings of this study are consistent with those of previous human studies, supporting weak yet noteworthy associations between dyslipidaemia and leukocytosis.

Predicting new silent cerebral infarction after intracerebral hemorrhage using serum white blood cell count

Background

It has been confirmed that incidental silent cerebral infarctions (SCIs) found in healthy people may be risk factors for cerebrovascular diseases such as strokes and vascular dementia. The prospective study aimed to determine the utility of baseline serum white blood cell (WBC) counts to predict the emergence of new SCI after intracranial hemorrhage (ICH).

Methods

This is a prospective study. From January 2016 to December 2017, we recruited 171 patients admitted to the neurology department of the Affiliated Shuyang Hospital of Xuzhou Medical University with a first episode of ICH. Serum WBC count was measured on admission. SCI was detected by cranial magnetic resonance imaging (MRI) 14 days after the onset of the ICH. Receiver operating characteristic curve analysis was used to calculate the most appropriate cut-off values of the WBC count for differentiating patients with and without SCI at the end of the study period.

Results

New SCIs were detected in 28.07% of patients by cranial MRI. Multivariate logistic regression analysis showed that cerebral microbleeds (CMBs), raised WBC counts, and leukoaraiosis were independent risk factors for SCI. The most appropriate cut-off WBC count differentiating the two groups was 7.65×10⁹/L (sensitivity: 77.08%, specificity: 63.41%).

Conclusion

Elevated levels of serum WBC counts in patients with ICH are associated with SCI. There is potential value in using serum WBC counts to predict new SCI after an acute hemorrhagic stroke.

Preoperative Lymphocyte-to-Monocyte Ratio as a Prognostic Predictor of Long-Term Mortality in Cardiac Surgery Patients: A Propensity Score Matching Analysis

Aims: To evaluate the prognostic value of the preoperative lymphocyte-to-monocyte ratio (LMR) in patients who underwent cardiac surgery. Methods: Clinical data were extracted from the Medical Information Mart for Intensive Care III (MIMIC-III) database. The optimal cutoff value of LMR was determined by X-tile software. The Cox proportional hazard model was applied for the identification of independent prognostic factors of 4-year mortality and survival curves were estimated using the Kaplan-Meier method. In order to balance the influence of potential confounding factors, a 1:1 propensity score matching (PSM) method was performed. Results: A total of 1,701 patients were included. The X-tile software indicated that the optimal cutoff value of the LMR for 4-year mortality was 3.58. After PSM, 489 pairs of score-matched patients were generated. The Cox proportional hazard model showed that patients with an LMR < 3.58 had a significantly higher 4-year mortality than patients with an LMR ≥ 3.58 in the entire cohort (HR = 1.925, 95%CI: 1.509-2.456, p < 0.001) and the PSM subset (HR = 1.568, 95%CI: 1.2-2.05, p = 0.001). The survival curves showed that patients with an LMR < 3.58 had a significant lower 4-year survival rate in the entire cohort (71.7 vs. 88.5%, p < 0.001) and the PSM subset (73.2 vs. 81.4%, p = 0.002). Conclusions: A lower LMR (<3.58) was associated with a higher risk of 4-year mortality and can serve as a prognostic predictor of the long-term mortality in cardiac surgery patients.

Diminished Reactive Hematopoiesis and Cardiac Inflammation in a Mouse Model of Recurrent Myocardial Infarction

BACKGROUND

Recurrent myocardial infarction (MI) is common in patients with coronary artery disease and is associated with high mortality. Long-term reprogramming of myeloid progenitors occurs in response to inflammatory stimuli and alters the organism's response to secondary inflammatory challenges.

OBJECTIVES

This study examined the effect of recurrent MI on bone marrow response and cardiac inflammation.

METHODS

The investigators developed a surgical mouse model in which 2 subsequent MIs affected different left ventricular regions in the same mouse. Recurrent MI was induced by ligating the left circumflex artery followed by the left anterior descending coronary artery branch. The study characterized the resulting ischemia by whole-heart fluorescent coronary angiography after optical organ clearing and by cardiac magnetic resonance imaging.

RESULTS

A first MI-induced bone marrow "memory" via a circulating signal, reducing hematopoietic maintenance factor expression in bone marrow macrophages. This dampened the organism's reaction to subsequent events. Despite a similar extent of injury according to troponin levels, recurrent MI caused reduced emergency hematopoiesis and less leukocytosis than a first MI. Consequently, fewer leukocytes migrated to the ischemic myocardium. The hematopoietic response to lipopolysaccharide was also mitigated after a previous MI. The increase of white blood count in 28 patients was lower after recurrent MI compared with their first MI.

CONCLUSIONS

The data suggested that hematopoietic and innate immune responses are shaped by a preceding MI.

Leukemoid reaction causing arterial thrombus in a patient with lung adenocarcinoma

A leukemoid reaction is typically defined as white blood cell (WBC) count >50×10⁹/L, predominantly neutrophil precursors, that are not due to tumour involvement in the bone marrow and not derived from clones. Leukemoid reactions associated with malignancy, known as paraneoplastic leukemoid reactions, are less common and are most notably seen with non-small cell lung cancer. A 64-year-old woman presented with right leg painful ulceration. On examination, she had multiple venous stasis ulcers more severe on the right, with no palpable pulses in her lower extremities. Her WBC count was 124×10⁹/L and platelets were 517×10⁹/L. Arterial dopplers showed limb-threatening arterial insufficiency which prompted right femoral endarterectomy. Few months earlier she was diagnosed with metastatic lung adenocarcinoma to the bone and she had leukemoid reaction with WBC 43.920× 10⁹/L with 90% neutrophils. Repeat imaging showed progression of her malignancy and she passed shortly after. Inflammation is a key element of carcinogenesis and cancer progression. Among the different tumours, lung cancer is a non-haematologic malignancy that is most closely associated with leucocytosis. Some studies have found that leucocytosis was significantly associated with metastasis and shorter survival irrespective of other factors such as age or sex. The mechanism remains unclear however elevated levels of granulocyte colony-stimulating factor (CSF), granulocyte macrophage-CSF and interleukin 6 have been linked to this phenomena. The degree of leucocytosis seen in our patient is suggestive of CSF production leading to a paraneoplastic leukemoid reaction.

Once-Daily Low Inflammatory Foods Everyday (LIFE) Smoothie or the Full LIFE Diet Lowers C-Reactive Protein and Raises Plasma Beta-Carotene in 7 Days

Serum C-reactive protein (CRP), a marker of systemic inflammation, is associated with increased risk for numerous inflammation-driven chronic diseases. A prior longitudinal study showed that the Low Inflammatory Foods Everyday (LIFE) diet, which is rich in dark green leafy vegetables (DGLV), lowered CRP over a mean follow-up period of 6 months. In this retrospective study, we investigate whether patients who consume the LIFE diet or their regular diet plus one component of the LIFE diet (LIFE smoothie), experience reductions in high-sensitivity CRP (hsCRP) in 7 days. Sixteen patients in a community practice met inclusion criteria. Patient compliance was assessed by patient interviews and measurements of beta-carotene, which is abundant in DGLV. Following the interventions, CRP decreased in both the LIFE diet (−0.47 mg/L, P = .02) and smoothie groups (−1.2 mg/L, P = .04). No statistically significant difference in reduction was observed between groups ( P = .18). Plasma beta-carotene increased in both groups (+23.2, P = .02; +20.6, P = .006, respectively). These findings suggest that the LIFE diet or a regular American diet supplemented with the LIFE smoothie may quickly reduce systemic inflammation and the risk of many chronic diseases.

Inhibition of JAK2 Suppresses Myelopoiesis and Atherosclerosis in Apoe-/- Mice

OBJECTIVE

Increased myelopoiesis has been linked to risk of atherosclerotic cardiovascular disease (ACD). Excessive myelopoiesis can be driven by dyslipidemia and cholesterol accumulation in hematopoietic stem and progenitor cells (HSPC) and may involve increased signaling via Janus kinase 2 (JAK2). Constitutively activating JAK2 mutants drive biased myelopoiesis and promote development of myeloproliferative neoplasms (MPN) or clonal hematopoiesis, conditions associated with increased risk of ACD. JAK2 inhibitors have been developed as a therapy for MPNs. The potential for JAK2 inhibitors to protect against atherosclerosis has not been tested. We therefore assessed the impact of JAK2 inhibition on atherogenesis.

METHODS

A selective JAK2 inhibitor TG101348 (fedratinib) or vehicle was given to high-fat high-cholesterol Western diet (WD)-fed wild-type (WT) or Apoe^-/- mice. Hematopoietic cell profiles, cell proliferation, and atherosclerosis in WT or Apoe^-/- mice were assessed.

RESULTS

TG101348 selectively reversed neutrophilia, monocytosis, HSPC, and granulocyte-macrophage progenitor (GMP) expansion in Apoe^-/- mice with decreased cellular phosphorylated STAT5 and ERK1/2 and reduced cell cycling and BrdU incorporation in HSPCs, indicating inhibition of JAK/STAT signaling and cell proliferation. Ten-week WD feeding allowed the development of marked aortic atherosclerosis in Apoe^-/- mice which was substantially reduced by TG101348.

CONCLUSIONS

Selective JAK2 inhibition reduces atherogenesis by suppressing excessive myelopoiesis in hypercholesterolemic Apoe^-/- mice. These findings suggest selective JAK2 inhibition as a potential therapeutic approach to decrease ACD risk in patients with increased myelopoiesis and leukocytosis.

Case of COVID-19 infection and polycythaemia presenting with massive acute pulmonary embolism

We are reporting a middle-aged male patient with polycythaemia vera comorbidity. The patient was exhibiting symptoms including fever, cough and shortness of breath and was found to have acute pulmonary embolism. He was diagnosed with SARS-CoV-2. This case suggests that a high index of suspicion should be taken into consideration for thromboembolic events, when treating patients with COVID-19 with breathing difficulty and low oxygen saturation levels, especially in those who have underlying predisposing conditions for coagulopathy.

Impact of Cholesterol Metabolism in Immune Cell Function and Atherosclerosis

Cholesterol, the most important sterol in mammals, helps maintain plasma membrane fluidity and is a precursor of bile acids, oxysterols, and steroid hormones. Cholesterol in the body is obtained from the diet or can be de novo synthetized. Cholesterol homeostasis is mainly regulated by the liver, where cholesterol is packed in lipoproteins for transport through a tightly regulated process. Changes in circulating lipoprotein cholesterol levels lead to atherosclerosis development, which is initiated by an accumulation of modified lipoproteins in the subendothelial space; this induces significant changes in immune cell differentiation and function. Beyond lesions, cholesterol levels also play important roles in immune cells such as monocyte priming, neutrophil activation, hematopoietic stem cell mobilization, and enhanced T cell production. In addition, changes in cholesterol intracellular metabolic enzymes or transporters in immune cells affect their signaling and phenotype differentiation, which can impact on atherosclerosis development. In this review, we describe the main regulatory pathways and mechanisms of cholesterol metabolism and how these affect immune cell generation, proliferation, activation, and signaling in the context of atherosclerosis.

Circadian Features of Neutrophil Biology

Rhythms in immunity manifest in multiple ways, but perhaps most prominently by the recurrent onset of inflammation at specific times of day. These patterns are of importance to understand human disease and are caused, in many instances, by the action of neutrophils, a myeloid leukocyte with striking circadian features. The neutrophil's short life, marked diurnal variations in number, and changes in phenotype while in the circulation, help explain the temporal features of inflammatory disease but also uncover core features of neutrophil physiology. Here, we summarize well-established concepts and introduce recent discoveries in the biology of these cells as they relate to circadian rhythms. We highlight that although the circadian features of neutrophils are better known and relevant to understand disease, they may also influence important aspects of organ function even in the steady-state. Finally, we discuss the possibility of targeting these temporal features of neutrophils for therapeutic benefit.

Neutrophil-Derived S100A8/A9 Amplify Granulopoiesis After Myocardial Infarction

BACKGROUND

Myocardial infarction (MI) triggers myelopoiesis, resulting in heightened production of neutrophils. However, the mechanisms that sustain their production and recruitment to the injured heart are unclear.

METHODS

Using a mouse model of the permanent ligation of the left anterior descending artery and flow cytometry, we first characterized the temporal and spatial effects of MI on different myeloid cell types. We next performed global transcriptome analysis of different cardiac cell types within the infarct to identify the drivers of the acute inflammatory response and the underlying signaling pathways. Using a combination of genetic and pharmacological strategies, we identified the sequelae of events that led to MI-induced myelopoiesis. Cardiac function was assessed by echocardiography. The association of early indexes of neutrophilia with major adverse cardiovascular events was studied in a cohort of patients with acute MI.

RESULTS

Induction of MI results in rapid recruitment of neutrophils to the infarct, where they release specific alarmins, S100A8 and S100A9. These alarmins bind to the Toll-like receptor 4 and prime the nod-like receptor family pyrin domain-containing 3 inflammasome in naïve neutrophils and promote interleukin-1β secretion. The released interleukin-1β interacts with its receptor (interleukin 1 receptor type 1) on hematopoietic stem and progenitor cells in the bone marrow and stimulates granulopoiesis in a cell-autonomous manner. Genetic or pharmacological strategies aimed at disruption of S100A8/A9 and their downstream signaling cascade suppress MI-induced granulopoiesis and improve cardiac function. Furthermore, in patients with acute coronary syndrome, higher neutrophil count on admission and after revascularization correlates positively with major adverse cardiovascular disease outcomes.

CONCLUSIONS

Our study provides novel evidence for the primary role of neutrophil-derived alarmins (S100A8/A9) in dictating the nature of the ensuing inflammatory response after myocardial injury. Therapeutic strategies aimed at disruption of S100A8/A9 signaling or their downstream mediators (eg, nod-like receptor family pyrin domain-containing 3 inflammasome, interleukin-1β) in neutrophils suppress granulopoiesis and may improve cardiac function in patients with acute coronary syndrome.

Monocytes and macrophages in atherogenesis

PURPOSE OF REVIEW

Monocytes and macrophages are key players in the pathogenesis of atherosclerosis and dictate atherogenesis growth and stability. The heterogeneous nature of myeloid cells concerning their metabolic and phenotypic function is increasingly appreciated. This review summarizes the recent monocyte and macrophage literature and highlights how differing subsets contribute to atherogenesis.

RECENT FINDINGS

Monocytes are short-lived cells generated in the bone marrow and released to circulation where they can produce inflammatory cytokines and, importantly, differentiate into long-lived macrophages. In the context of cardiovascular disease, a myriad of subtypes, exist with each differentially contributing to plaque development. Herein we describe recent novel characterizations of monocyte and macrophage subtypes and summarize the recent literature on mediators of myelopoiesis.

SUMMARY

An increased understanding of monocyte and macrophage phenotype and their molecular regulators is likely to translate to the development of new therapeutic targets to either stem the growth of existing plaques or promote plaque stabilization.

Cardioimmunology: the immune system in cardiac homeostasis and disease

The past few decades have generated growing recognition that the immune system makes an important contribution to cardiac development, composition and function. Immune cells infiltrate the heart at gestation and remain in the myocardium, where they participate in essential housekeeping functions throughout life. After myocardial infarction or in response to infection, large numbers of immune cells are recruited to the heart to remove dying tissue, scavenge pathogens and promote healing. Under some circumstances, immune cells can cause irreversible damage, contributing to heart failure. This Review focuses on the role of the immune system in the heart under both homeostatic and perturbed conditions.

Artery-Associated Sympathetic Innervation Drives Rhythmic Vascular Inflammation of Arteries and Veins

BACKGROUND

The incidence of acute cardiovascular complications is highly time-of-day dependent. However, the mechanisms driving rhythmicity of ischemic vascular events are unknown. Although enhanced numbers of leukocytes have been linked to an increased risk of cardiovascular complications, the role that rhythmic leukocyte adhesion plays in different vascular beds has not been studied.

METHODS

We evaluated leukocyte recruitment in vivo by using real-time multichannel fluorescence intravital microscopy of a tumor necrosis factor-α-induced acute inflammation model in both murine arterial and venous macrovasculature and microvasculature. These approaches were complemented with genetic, surgical, and pharmacological ablation of sympathetic nerves or adrenergic receptors to assess their relevance for rhythmic leukocyte adhesion. In addition, we genetically targeted the key circadian clock gene Bmal1 (also known as Arntl) in a lineage-specific manner to dissect the importance of oscillations in leukocytes and components of the vessel wall in this process.

RESULTS

In vivo quantitative imaging analyses of acute inflammation revealed a 24-hour rhythm in leukocyte recruitment to arteries and veins of the mouse macrovasculature and microvasculature. Unexpectedly, although in arteries leukocyte adhesion was highest in the morning, it peaked at night in veins. This phase shift was governed by a rhythmic microenvironment and a vessel type-specific oscillatory pattern in the expression of promigratory molecules. Differences in cell adhesion molecules and leukocyte adhesion were ablated when disrupting sympathetic nerves, demonstrating their critical role in this process and the importance of β₂-adrenergic receptor signaling. Loss of the core clock gene Bmal1 in leukocytes, endothelial cells, or arterial mural cells affected the oscillations in a vessel type-specific manner. Rhythmicity in the intravascular reactivity of adherent leukocytes resulted in increased interactions with platelets in the morning in arteries and in veins at night with a higher predisposition to acute thrombosis at different times as a consequence.

CONCLUSIONS

Together, our findings point to an important and previously unrecognized role of artery-associated sympathetic innervation in governing rhythmicity in vascular inflammation in both arteries and veins and its potential implications in the occurrence of time-of-day-dependent vessel type-specific thrombotic events.

Monocytes, Macrophages, and Metabolic Disease in Atherosclerosis

Atherosclerotic cardiovascular disease (CVD) is a lipid-driven chronic inflammatory disease, in which macrophages are responsible for taking up these lipids and driving disease progression. Over the years, we and others have uncovered key pathways that regulate macrophage number/function and identified how metabolic disorders such as diabetes and obesity, which are common risk factors for CVD, exacerbate these pathways. This ultimately accelerates the progression of atherosclerosis and hinders atherosclerotic regression. In this review, we discuss the different types of macrophages, from monocyte-derived macrophages, local macrophage proliferation, to macrophage-like vascular smooth muscle cells, that contribute to atherosclerosis as well as myeloid-derived suppressor cells that may have anti-atherogenic effects. We will also discuss how diabetes and obesity influence plaque macrophage accumulation and monocyte production (myelopoiesis) to promote atherogenesis as well as an exciting therapeutic target, S100A8/A9, which mediates myelopoiesis in response to both diabetes and obesity, shown to be effective in reducing atherosclerosis in pre-clinical models of diabetes.

Association of glycemic status and interferon-γ production with leukocytes and platelet indices alterations in type2 diabetes

AIMS

The present study aimed to evaluate the correlation between glycemic status and the inflammation biomarkers; leukocytes, platelets indices and interferon gamma (IFN-γ) production in type 2 diabetes mellitus (T2DM) patients regarding diabetic complications.

METHODS

Study was conducted on 158 patients allocated as normal healthy subjects (50) and 108 patients diagnosed as T2DM. The diabetic patients were subdivided into six groups according to metformin administration as mono-or dual therapies.

RESULTS

The current results exhibited a significant elevation in systolic blood pressure, total and LDL-cholesterol levels and IFN-γ as well as a noticeable decrease in HDL-cholesterol and anti-atherogenic factor values compared to the healthy patients. Leukocytes and neutrophils count, main platelets volume (MPV) and platelet distribution width (PDW) values revealed noticeable elevations in most treated T2DM groups, while a marked depletion was recorded in platelets count compared to healthy subjects. Glycemic control, most treated diabetic patients with metformin mono- and dual therapies showed an ameliorative effect in HbA1c, IFN-γ, MPV, and PDW values compared to recent diabetic ones.

CONCLUSION

Diabetes was correlated significantly with dyslipidemia and atherogenic risk in parallel with an increase in IFN-γ production and hematological inflammatory biomarkers; leukocytes, neutrophil/lymphocyte and platelet/lymphocyte ratios, MPV and PDW values. The amelioration in inflammatory biomarkers was associated with improvement in glycemic control.

Multiple Faces of Chronic Lymphocytic Leukaemia: A Patient with Renal, Cardiac, and Skeletal Complications

We describe a patient who had chronic lymphocytic leukaemia (CLL) Binet stage A at presentation with further evidence of disease at multiple sites but who initially required no treatment. However, several years later, her peripheral blood lymphocyte count started to increase, and soon after that she suffered an acute myocardial infarct (in the absence of coronary atheroma) together with proteinuric renal failure due to membranoproliferative glomerulonephritis. Her renal function improved markedly following anti-CLL chemotherapy. We postulate that her cardiac and renal disease were both complications of her CLL. In patients with CLL who develop new clinical signs or symptoms (even if apparently unrelated), consideration should be given as to whether these may be disease complications as this may serve as an indication to commence anti-CLL therapy; close liaison between different specialties is vital.

Cytokine Circuits in Cardiovascular Disease

Arterial inflammation is a hallmark of atherosclerosis, and appropriate management of this inflammation represents a major unmet therapeutic need for cardiovascular disease patients. Here, we review the diverse contributions of immune cells to atherosclerosis, the mechanisms of immune cell activation in this context, and the cytokine circuits that underlie disease progression. We discuss the recent application of these insights in the form of immunotherapy to treat cardiovascular disease and highlight how studies on the cardiovascular co-morbidity that arises in autoimmunity might reveal additional roles for cytokines in atherosclerosis. Currently, data point to interleukin-1β (IL-1β), tumor necrosis factor (TNF), and IL-17 as cytokines that, at least in some settings, are effective targets to reduce cardiovascular disease progression.

Unfolding of hidden white blood cell count phenotypes for gene discovery using latent class mixed modeling

Resting-state white blood cell (WBC) count is a marker of inflammation and immune system health. There is evidence that WBC count is not fixed over time and there is heterogeneity in WBC trajectory that is associated with morbidity and mortality. Latent class mixed modeling (LCMM) is a method that can identify unobserved heterogeneity in longitudinal data and attempts to classify individuals into groups based on a linear model of repeated measurements. We applied LCMM to repeated WBC count measures derived from electronic medical records of participants of the National Human Genetics Research Institute (NHRGI) electronic MEdical Record and GEnomics (eMERGE) network study, revealing two WBC count trajectory phenotypes. Advancing these phenotypes to GWAS, we found genetic associations between trajectory class membership and regions on chromosome 1p34.3 and chromosome 11q13.4. The chromosome 1 region contains CSF3R, which encodes the granulocyte colony-stimulating factor receptor. This protein is a major factor in neutrophil stimulation and proliferation. The association on chromosome 11 contain genes RNF169 and XRRA1; both involved in the regulation of double-strand break DNA repair.