Enzymatic lipid oxidation by eosinophils propagates coagulation, hemostasis, and thrombotic disease

Arterial and venous thrombosis in systemic and monogenic vasculitis

Systemic vasculitis, common forms of which include anti-neutrophil cytoplasmic antibody-associated small-vessel vasculitis, large-vessel vasculitis and Behçet syndrome, are frequently complicated by arterial or venous thrombotic events (AVTEs). Newly identified entities such as DADA2 (deficiency of adenosine deaminase 2) and VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome, which are driven by genetic mutations, also exhibit vasculitic features and are associated with a high risk of AVTEs. AVTEs in systemic vasculitis, including monogenic forms of vasculitis, are due to the complex interaction of inflammation and coagulation. New insights into the pathogenetic mechanisms implicate endothelial dysfunction, immune complex deposition and the interplay of pro-inflammatory cytokines with prothrombotic factors, which collectively promote thrombus formation. AVTEs impose a substantial disease burden, complicate diagnosis and negatively affect prognosis by increasing the risk of morbidity and mortality. Early diagnosis and treatment are crucial to prevent lasting damage. Management strategies should target both thrombosis and underlying inflammation. Antithrombotic therapies, including low-dose aspirin, or oral anticoagulants should be used on the basis of individual thrombotic risk assessment. Immunosuppressive therapy is the cornerstone of treatment for arterial and venous thrombosis, particularly in Behçet syndrome, in which vascular inflammation has a crucial role in thrombotic complications.

Recent Advances in Immunothrombosis and Thromboinflammation

Inflammation and thrombosis are traditionally considered two separate entities of acute host responses to barrier breaks. While inciting inflammatory responses is a prerequisite to fighting invading pathogens and subsequent restoration of tissue homeostasis, thrombus formation is a crucial step of the hemostatic response to prevent blood loss following vascular injury. Though originally designed to protect the host, excessive induction of either inflammatory signaling or thrombus formation and their reciprocal activation contribute to a plethora of disorders, including cardiovascular, autoimmune, and malignant diseases. In this state-of-the-art review, we summarize recent insights into the intricate interplay of inflammation and thrombosis. We focus on the protective aspects of immunothrombosis as well as evidence of detrimental sequelae of thromboinflammation, specifically regarding recent studies that elucidate its pathophysiology beyond coronavirus disease 2019 (COVID-19). We introduce recently identified molecular aspects of key cellular players like neutrophils, monocytes, and platelets that contribute to both immunothrombosis and thromboinflammation. Further, we describe the underlying mechanisms of activation involving circulating plasma proteins and immune complexes. We then illustrate how these factors skew the inflammatory state toward detrimental thromboinflammation across cardiovascular as well as septic and autoimmune inflammatory diseases. Finally, we discuss how the advent of new technologies and the integration with clinical data have been used to investigate the mechanisms and signaling cascades underlying immunothrombosis and thromboinflammation. This review highlights open questions that will need to be addressed by the field to translate our mechanistic understanding into clinically meaningful therapeutic targeting.

Advanced Research in the Pathophysiology of Venous Thromboembolism-Acute Pulmonary Embolism

According to the literature, cardiovascular diseases (CVDs)-including myocardial infarction, stroke, and venous thromboembolism (VTE)-are among the leading causes of mortality and morbidity worldwide. Evidence suggests that CVDs share common risk factors and pathophysiological mechanisms. Similar to the Mosaic Theory of Hypertension proposed by Irvine Page in 1949, the pathophysiology of VTE is multifactorial, involving multiple interacting processes. The concept of immunothrombosis, introduced by Engelmann and Massberg in 2009, describes the interplay between the immune system and thrombosis. Both thrombosis and hemostasis share core mechanisms, including platelet activation and fibrin formation. Additionally, immune mediators-such as monocytes, neutrophil extracellular traps (NETs), lymphocytes, selectins, and various molecular factors-play a critical role in thrombus formation. This review highlights inflammation as a key risk factor for pulmonary embolism (APE). Immunity is central to the complex interactions among the coagulation cascade, platelets, endothelium, reactive oxygen species (ROS), and genetic factors. Specifically, we examine the roles of the endothelium, immune cells, and microRNAs (miRNAs) in the pathophysiology of APE and explore potential therapeutic targets. This review aims to elucidate the roles of the endothelium, immune cells, and miRNAs in the pathophysiology of APE and explore potential future perspective.

Lipidomic insights on abdominal aortic aneurysm and peripheral arterial disease

Abdominal aortic aneurysm (AAA) and peripheral arterial disease (PAD) are two cardiovascular diseases associated with considerable morbidity, mortality and quality of life impairment. As they are multifactorial diseases, several factors contribute to their pathogenesis, including oxidative stress and lipid peroxidation, and these may have key roles in the development of these pathologies. Alterations of the lipid metabolism and lipid profile have been reported in cardiovascular diseases but to a lesser extent in AAA and PAD. Modifications in the profile of some molecular lipid species, in particular, native phospholipid and triglyceride species were mainly reported for AAA, while alterations in the fatty acid profile were noticed in the case of PAD. Oxidized phospholipids were also reported for AAA. Although AAA and PAD have a common atherosclerotic root, lipidomics demonstrates the existence of distinct lipid. Lipidomic research regarding AAA and PAD is still scarce and should be set in motion to increase the knowledge on the lipid changes that occur in these diseases, contributing not only to the discovery of new biomarkers for diagnosis and prognosis assessment but also to tailor precision medicine in the clinical field.

Cardiovascular disease and thrombosis: Intersections with the immune system, inflammation, and the coagulation system

The coagulation and immune system, both essential physiological systems in the human body, are intricately interconnected and play a critical role in determining the overall health of patients. These systems collaborate via various shared regulatory pathways, such as the Tissue Factor (TF) Pathway. Immunological cells that express TF and generate pro-inflammatory cytokines have the ability to affect coagulation. Conversely, coagulation factors and processes have a reciprocal effect on immunological responses by stimulating immune cells and regulating their functions. These interconnected pathways play a role in both preserving well-being and contributing to a range of pathological disorders. The close relationship between blood clotting and inflammation in the development of vascular disease has become a central focus of clinical study. This research specifically examines the crucial elements of this interaction within the contexts of cardiovascular disease and acute coronary syndrome. Tissue factor, the primary trigger of the extrinsic coagulation pathway, has a crucial function by inducing a proinflammatory reaction through the activation of coagulation factors. This, in turn, initiates coagulation and subsequent cellular signalling pathways. Protease-activated receptors establish the molecular connection between coagulation and inflammation by interacting with activated clotting factors II, X, and VII. Thrombosis, a condition characterised by the formation of blood clots, is the most dreaded consequence of cardiovascular disorders and a leading cause of death globally. Consequently, it poses a significant challenge to healthcare systems. Antithrombotic treatments efficiently target platelets and the coagulation cascade, but they come with the inherent danger of causing bleeding. Furthermore, antithrombotics are unable to fully eliminate thrombotic events, highlighting a treatment deficiency caused by a third mechanism that has not yet been sufficiently addressed, namely inflammation. Understanding these connections may aid in the development of novel approaches to mitigate the harmful mutual exacerbation of inflammation and coagulation. Gaining a comprehensive understanding of the intricate interaction among these systems is crucial for the management of diseases and the creation of efficacious remedies. Through the examination of these prevalent regulatory systems, we can discover novel therapeutic approaches that specifically target these complex illnesses. This paper provides a thorough examination of the reciprocal relationship between the coagulation and immune systems, emphasising its importance in maintaining health and understanding disease processes. This review examines the interplay between inflammation and thrombosis and its role in the development of thrombotic disorders.

Differential roles of eosinophils in cardiovascular disease

Eosinophils are essential innate immune cells in allergic responses. Accumulating evidence indicates that eosinophils also participate in the pathogenesis of cardiovascular diseases (CVDs). In clinical studies, high blood eosinophil counts and eosinophil cationic protein levels have been associated with an increased risk of CVD, including myocardial infarction (MI), cardiac hypertrophy, atrial fibrillation, abdominal aortic aneurysm (AAA) and atherosclerosis. However, low blood eosinophil counts have also been reported to be a risk factor for MI, heart failure, aortic dissection, AAA, deep vein thrombosis, pulmonary embolism and ischaemic stroke. Although these conflicting clinical observations remain unexplained, CVD status, timing of eosinophil data collection, and tissue eosinophil phenotypic and functional heterogeneities might account for these discrepancies. Preclinical studies suggest that eosinophils have protective actions in MI, cardiac hypertrophy, heart failure and AAA. By contrast, cationic proteins and platelet-activating factor from eosinophils have been shown to promote vascular smooth muscle cell proliferation, vascular calcification, thrombomodulin inactivation and platelet activation and aggregation, thereby exacerbating atherosclerosis, atrial fibrillation, thrombosis and associated complications. Therefore, eosinophils seem to promote calcification and thrombosis in chronic CVD but are protective in acute cardiovascular settings. In this Review, we summarize the available clinical and preclinical data on the different roles of eosinophils in CVD.

Immunothrombosis in Acute Ischemic Stroke

Ischemic stroke is one of the leading causes of disability and mortality worldwide. Thrombosis is the main pathological process of stroke and is therefore an important therapeutic target in stroke prevention. In recent years, with the development of endovascular treatment and therefore retrieving the thrombus for further investigation, evidence is accumulating that immune cells are inextricably linked to stroke pathogenesis. Circulating immune cells have been found to induce immunothrombosis, and they actively participate in the formation of the thrombus by promoting platelet recruitment and thrombin activation. Additionally, the formation of thromboinflammation leads to increased instability of atherosclerotic plaques. We review the concepts of stroke immunothrombosis and thromboinflammation and the effect of immune cells on vessel recanalization and patient outcome. In addition, we elaborate on the possible mechanism of immune cells being activated and participating in thrombosis in ischemic stroke.

Bioactive electrospun polylactic acid/chlorogenic acid-modified chitosan bilayer sponge for acute infection wound healing and rapid coagulation

Acute severe trauma is often associated with rapid blood loss and a high risk of infection. Based on these concerns, this study successfully constructed a multifunctional dual-layer bioactive sponge PCCT with rapid hemostatic and infection-preventing ability. Its external surface is an electrospun poly(lactic acid) (PLA) nanofiber thin film layer, which ensures its high air permeability and effectively protects against external bacterial invasion. In vitro results showed that the film is effectively resistant to invasion by typical Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria. The inner sponge layer was formed by chlorogenic acid (CGA) grafted with chitosan (CS) and loaded with tranexamic acid (TA). The abundant cationic groups on the sponge interacted with negatively charged erythrocytes and achieved rapid hemostasis at the wound site under the action of TA. In addition, the high porosity and bioactivity of the CS-CGA sponge scaffold endowed the hydrogel with good water absorption, antibacterial properties and anti-inflammatory activity, which effectively accelerated the healing of acute infected wounds in rats and demonstrated favorable biosafety.

Aspirin modulates generation of procoagulant phospholipids in cardiovascular disease, by regulating LPCAT3

Enzymatically oxygenated phospholipids (eoxPL) from lipoxygenases (LOX) or cyclooxygenase (COX) are prothrombotic. Their generation in arterial disease, and their modulation by cardiovascular therapies is unknown. Furthermore, the Lands cycle acyl-transferases that catalyze their formation are unidentified. eoxPL were measured in platelets and leukocytes from an atherosclerotic cardiovascular disease (ASCVD) cohort and retrieved human arterial thrombi from three anatomical sites. The impact of age, gender, and aspirin was characterized in platelets from healthy subjects administered low-dose aspirin. The role of lysophosphatidylcholine acyltransferase 3 (LPCAT3) in eoxPL biosynthesis was tested using an inhibitor and a cell-free assay. Platelets from ASCVD patients generated lower levels of COX-derived eoxPL but elevated 12-LOX-diacyl forms, than platelets from healthy controls. This associated with aspirin and was recapitulated in healthy subjects by aspirin supplementation. P2Y12 inhibition had no impact on eoxPL. LPCAT3 inhibition selectively prevented 12-LOX-derived diacyl-eoxPL generation. LPCAT3 activity was not directly altered by aspirin. P2Y12 inhibition or aspirin had little impact on eoxPL in leukocytes. Complex aspirin-dependent gender and seasonal effects on platelet eoxPL generation were seen in healthy subjects. Limb or coronary (ST-elevation myocardial infarction, STEMI) thrombi displayed a platelet eoxPL signature while carotid thrombi had a white cell profile. EoxPL are altered in ASCVD by a commonly used cardiovascular therapy, and LPCAT3 was identified as the acyltransferase generating aspirin-sensitive 12-LOX diacyl forms. These changes to the phospholipid composition of blood cells in humans at risk of thrombosis may be clinically significant where the procoagulant membrane plays a central role in driving elevated thrombotic risk.

Metabolic landscape in venous thrombosis: insights into molecular biology and therapeutic implications

The findings of the last decade suggest a complex link between inflammatory cells, coagulation, and the activation of platelets and their synergistic interaction to promote venous thrombosis. Inflammation is present throughout the process of venous thrombosis, and various metabolic pathways of erythrocytes, endothelial cells, and immune cells involved in venous thrombosis, including glucose metabolism, lipid metabolism, homocysteine metabolism, and oxidative stress, are associated with inflammation. While the metabolic microenvironment has been identified as a marker of malignancy, recent studies have revealed that for cancer thrombosis, alterations in the metabolic microenvironment appear to also be a potential risk. In this review, we discuss how the synergy between metabolism and thrombosis drives thrombotic disease. We also explore the great potential of anti-inflammatory strategies targeting venous thrombosis and the complex link between anti-inflammation and metabolism. Furthermore, we suggest how we can use our existing knowledge to reduce the risk of venous thrombosis.

Nomogram models for predicting myocardial ischemia under high altitude exposure: a cohort study

BACKGROUND

Exposure to high altitude increases the risk of myocardial ischemia (MI) and subsequent cardiovascular death. Nomogram is a graphical regression model, but there are no reports on using nomogram to predict myocardial ischemia under high altitude exposure. Our goal was to establish prediction models based on pre-high-altitude physical exposure examination data and identify key risk factors.

METHODS

We prospectively enrolled a total of 2,855 healthy individuals who underwent physical examination at the 920th Hospital of Joint Logistics Support Force and were scheduled to undergo high-altitude (3000-3500 m) training within six months. These participants were randomly divided into a training cohort (75%) and a validation cohort (25%). In the training set, single-factor analysis of variance and Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis were used to select variables, and two nomograms were established based on clinical features (CF) and clinical features + blood tests (CF + BT), respectively. The performance of the nomograms was evaluated using the area under the receiver operating characteristic curve (ROC), the concordance index (C-index), and calibration curves.

RESULTS

The C-index for the prediction models CF and CF + BT were 0.652 and 0.804, respectively. In the training cohort, the AUC for prediction models CF and CF + BT were 0.61 and 0.80, respectively. In the validation cohort, the AUC for prediction models CF and CF + BT were 0.61 and 0.81, respectively.

CONCLUSION

We have successfully established two nomogram models to predict myocardial ischemia under high-altitude exposure and identified some risk factors.

The Role of Myeloid Cells in Thromboinflammatory Disease

Inflammation contributes to the development of thrombosis, but the mechanistic basis for this association remains poorly understood. Innate immune responses and coagulation pathways are activated in parallel following infection or injury, and represent an important host defense mechanism to limit pathogen spread in the bloodstream. However, dysregulated proinflammatory activity is implicated in the progression of venous thromboembolism and arterial thrombosis. In this review, we focus on the role of myeloid cells in propagating thromboinflammation in acute inflammatory conditions, such as sepsis and coronavirus disease 2019 (COVID-19), and chronic inflammatory conditions, such as obesity, atherosclerosis, and inflammatory bowel disease. Myeloid cells are considered key drivers of thromboinflammation via upregulated tissue factor activity, formation of neutrophil extracellular traps (NETs), contact pathway activation, and aberrant coagulation factor-mediated protease-activated receptor (PAR) signaling. We discuss how strategies to target the intersection between myeloid cell-mediated inflammation and activation of blood coagulation represent an exciting new approach to combat immunothrombosis. Specifically, repurposed anti-inflammatory drugs, immunometabolic regulators, and NETosis inhibitors present opportunities that have the potential to dampen immunothrombotic activity without interfering with hemostasis. Such therapies could have far-reaching benefits for patient care across many thromboinflammatory conditions.

Hot under the clot: venous thrombogenesis is an inflammatory process

ABSTRACT

Venous thrombosis (VT) is a serious medical condition in which a blood clot forms in deep veins, often causing limb swelling and pain. Current antithrombotic therapies carry significant bleeding risks resulting from targeting essential coagulation factors. Recent advances in this field have revealed that the cross talk between the innate immune system and coagulation cascade is a key driver of VT pathogenesis, offering new opportunities for potential therapeutic interventions without inducing bleeding complications. This review summarizes and discusses recent evidence from preclinical models on the role of inflammation in VT development. We highlight the major mechanisms by which endothelial cell activation, Weibel-Palade body release, hypoxia, reactive oxygen species, inflammasome, neutrophil extracellular traps, and other immune factors cooperate to initiate and propagate VT. We also review emerging clinical data describing anti-inflammatory approaches as adjuncts to anticoagulation in VT treatment. Finally, we identify key knowledge gaps and future directions that could maximize the benefit of anti-inflammatory therapies in VT. Identifying and targeting the inflammatory factors driving VT, either at the endothelial cell level or within the clot, may pave the way for new therapeutic possibilities for improving VT treatment and reducing thromboembolic complications without increasing bleeding risk.

Oxylipin profiling for clinical research: Current status and future perspectives

Oxylipins are potent lipid mediators with increasing interest in clinical research. They are usually measured in systemic circulation and can provide a wealth of information regarding key biological processes such as inflammation, vascular tone, or blood coagulation. Although procedures still require harmonization to generate comparable oxylipin datasets, performing comprehensive profiling of circulating oxylipins in large studies is feasible and no longer restricted by technical barriers. However, it is essential to improve and facilitate the biological interpretation of complex oxylipin profiles to truly leverage their potential in clinical research. This requires regular updating of our knowledge about the metabolism and the mode of action of oxylipins, and consideration of all factors that may influence circulating oxylipin profiles independently of the studied disease or condition. This review aims to provide the readers with updated and necessary information regarding oxylipin metabolism, their different forms in systemic circulation, the current limitations in deducing oxylipin cellular effects from in vitro bioactivity studies, the biological and technical confounding factors needed to consider for a proper interpretation of oxylipin profiles.

Involvement of peptidylarginine deiminase 4 in eosinophil extracellular trap formation and contribution to citrullinated histone signal in thrombi

BACKGROUND

Extracellular traps formed by neutrophils (NETs) and eosinophils (EETs) have been described in coronary thrombi, contributing to thrombus stability. A key mechanism during NET formation is histone modification by the enzyme PAD4. Citrullinated histones, the product of PAD4 activity, are often attributed to neutrophils. Eosinophils also express high levels of PAD4.

OBJECTIVES

We aimed to explore the contribution of PAD4 to EET formation.

METHODS

We performed immunohistological analyses on thrombi, including a large, intact, and eosinophil-containing thrombus retrieved from the right coronary artery using an aspiration catheter and stroke thrombi from thrombectomy retrieval. We studied eosinophils for their capability to form PAD4-dependent EETs in response to strong ET-inducing agonists as well as activated platelets and bacteria.

RESULTS

Histopathology and immunofluorescence microscopy identified a coronary thrombus rich in platelets and neutrophils, with distinct areas containing von Willebrand factor and citrullinated histone H3 (H3Cit). Eosinophils were also identified in leukocyte-rich areas. The majority of the H3Cit+ signal colocalized with myeloperoxidase, but some colocalized with eosinophil peroxidase, indicating EETs. Eosinophils isolated from healthy volunteers produced H3Cit+ EETs, indicating an involvement of PAD4 activity. The selective PAD4 inhibitor GSK484 blocked this process, supporting PAD4 dependence of H3Cit+ EET release. Citrullinated histones were also present in EETs produced in response to live Staphylococci. However, limited evidence for EETs was found in mouse models of venous thrombosis or infective endocarditis.

CONCLUSION

As in NETosis, PAD4 can catalyze the formation of EETs. Inhibition of PAD4 decreases EET formation, supporting the future utility of PAD4 inhibitors as possible antithrombotic agents.

Relationship between thrombus vWF and NETs with clinical severity and peripheral blood immunocytes' indicators in patients with acute ischemic stroke

OBJECTIVE

To investigate the association between von Willebrand factor (vWF) and neutrophil extracellular traps (NETs) in thrombus with clinical severity and peripheral blood immunocytes' indicators in patients with early-stage acute ischemic stroke (AIS).

METHODS

A retrospective study was conducted using the clinical data of 66 patients with AIS who underwent endovascular mechanical thrombectomy and had their thrombus samples collected. The concentrations of vWF and NETs in the thrombus samples were quantitatively assessed. Peripheral blood samples taken in the early stages of the disease were analyzed for total white blood cell counts (WBC), ratios of neutrophils (NEU%), lymphocytes (LYM%), eosinophils (EOS%), and monocytes (MONO%). The severity of clinical symptoms in these patients was evaluated using the modified Rankin Scale (mRS), Essen Stroke Risk Score (ESRS), Barthel Index (BI), and National Institute of Health Stroke Scale (NIHSS).

RESULTS

Higher vWF levels in thrombus were associated with lower NIHSS scores, while higher NETs levels were associated with higher initial NIHSS scores. In the early stages of AIS, WBC count and vWF levels were negatively correlated, as well as NEU%. LYM% was positively correlated with vWF level; however, it was negatively correlated with NETs. EOS% was positively correlated with vWF levels.

CONCLUSION

In the early stages of AIS, a higher peripheral WBC count and NEU%, combined with decreased EOS% and LYM%, were significantly correlated with a lower vWF level in the thrombus, potentially indicating more severe symptoms. Consequently, the timely administration of vWF-targeted medications is recommended for such patients. Reduced LYM% is indicative of elevated NETs levels and correlated with more severe clinical symptoms. Therefore, the prompt initiation of NETs-targeted medication is warranted for these patients.

Hematopoietic and eosinophil-specific LNK(SH2B3) deficiency promotes eosinophilia and arterial thrombosis

ABSTRACT

Increased eosinophil counts are associated with cardiovascular disease and may be an independent predictor of major cardiovascular events. However, the causality and underlying mechanisms are poorly understood. Genome-wide association studies have shown an association of a common LNK variant (R262W, T allele) with eosinophilia and atherothrombotic disorders. LNK(TT) reduces LNK function, and Lnk-deficient mice display accelerated atherosclerosis and thrombosis. This study was undertaken to assess the role of eosinophils in arterial thrombosis in mice with hematopoietic Lnk deficiency. Hematopoietic Lnk deficiency increased circulating and activated eosinophils, JAK/STAT signaling in eosinophils, and carotid arterial thrombosis with increased eosinophil abundance and extracellular trap formation (EETosis) in thrombi. Depletion of eosinophils by anti-Siglec-F antibody or by the ΔdbIGata1 mutation eliminated eosinophils in thrombi and markedly reduced thrombosis in mice with hematopoietic Lnk deficiency but not in control mice. Eosinophil depletion reduced neutrophil abundance and NETosis in thrombi without altering circulating neutrophil counts. To assess the role of Lnk specifically in eosinophils, we crossed Lnkf/f mice with eoCre mice. LnkΔeos mice displayed isolated eosinophilia, increased eosinophil activation, and accelerated arterial thrombosis associated with increased EETosis and NETosis in thrombi. DNase I infusion abolished EETs and neutrophil extracellular traps (NETs) in thrombi and reversed the accelerated thrombosis. Human induced pluripotent stem cell-derived LNK(TT) eosinophils showed increased activation and EETosis relative to isogenic LNK(CC) eosinophils, demonstrating human relevance. These studies show a direct link between eosinophilia, EETosis, and atherothrombosis in hematopoietic Lnk deficiency and an essential role of eosinophil LNK in suppression of arterial thrombosis.

Ophthalmic vascular manifestations in eosinophil-associated diseases: a comprehensive analysis of 57 patients from the CEREO and EESG networks and a literature review

Introduction

Eosinophils have widespread procoagulant effects. In daily practice, eosinophil-related cardiovascular toxicity consists of endomyocardial damage, eosinophilic vasculitis and arterial or venous thrombosis. Here we aim to report on the clinical features and treatment outcomes of patients with unexplained ophthalmic vascular manifestations and eosinophilia.

Methods

We conducted a retrospective, multicenter, observational study and a literature review of patients with eosinophilia (≥0.5 x109/L) and concomitant ophthalmic vascular manifestations independent of the underlying eosinophilic disease but with no alternative cause for ophthalmic manifestations.

Results

Fifty-seven patients were included (20 from the observational study and 37 from the literature review). Ophthalmic vascular features were the initial manifestation of eosinophil-related disease in 34 (59%) patients and consisted of 29 central retinal artery occlusions, six branch retinal artery occlusions, five central retinal vein occlusions, two branch retinal vein occlusions, seven retinal vasculitides, two retinal vasospasms, 12 Purtscher's retinopathies, 13 anterior ischemic optic neuropathies and two posterior ischemic optic neuropathies. The median [IQR] absolute eosinophil count at onset of ophthalmic vascular manifestations was 3.5 [1.7-7.8] x109/L. Underlying eosinophil-related diseases included eosinophilic granulomatosis with polyangiitis (n=32), clonal hypereosinophilic syndrome (HES) (n=1), idiopathic HES (n=13), lymphocytic HES (n=2), adverse drug reactions (n=3), parasitosis (n=2), polyarteritis nodosa (n=1), IgG4-related disease (n=1), eosinophilic fasciitis (n=1) and primary sclerosing cholangitis (n=1). Other extra-ophthalmologic arterial or venous thromboses related to eosinophilia were reported in four (7%) and nine (16%) patients, respectively. Visual prognosis was poor: only eight (10%) patients achieved full recovery of ophthalmologic symptoms. After a median follow-up of 10.5 [1-18] months, one patient (3%) had a recurrence of an ophthalmic vascular manifestation, and three patients (10%) had a recurrence of other vascular symptoms (deep vein thrombosis in two and pulmonary embolism in one patient). At the time of recurrence, absolute eosinophil counts were above 0.5 x109/L in all cases (n=4).

Discussion

This study broadens the spectrum of vascular manifestations associated with hypereosinophilia by adding ophthalmic vascular manifestations. In patients with ophthalmological vascular manifestations and hypereosinophilia, aggressive treatment of the underlying pathology (and normalization of blood count) should be implemented.

Interstitial Eosinophilic Aggregates and Kidney Outcome in Patients with CKD

BACKGROUND

Interstitial eosinophilic aggregates are observed in various kidney diseases, but their clinical implications remain unknown. We assessed the association between interstitial eosinophilic aggregates and kidney outcomes and further analyzed the association between blood eosinophil count, as a surrogate for interstitial eosinophilic aggregates, and the risk of kidney failure in patients with advanced CKD.

METHODS

We analyzed datasets from two retrospective cohort studies: ( 1 ) the kidney biopsy cohort including 563 patients who underwent native kidney biopsy at Osaka University Hospital between 2009 and 2021 and ( 2 ) the retrospective CKD cohort including 2877 patients with an eGFR of 10-60 ml/min per 1.73 m 2 referred to the nephrology outpatient center at Osaka University Hospital between 2005 and 2018. Interstitial eosinophilic aggregates were defined as ≥5 interstitial eosinophils in the high-power field on hematoxylin and eosin staining. This study outcome was initiation of KRT or ≥40% decline in eGFR.

RESULTS

In the kidney biopsy cohort, interstitial eosinophilic aggregates were found in 17% of patients, most frequently in those with diabetic nephropathy (50%). Interstitial eosinophilic aggregates were associated with a higher rate of the composite kidney outcome after adjustment for clinical and histological variables (hazard ratio, 3.61; 95% confidence interval, 2.47 to 5.29; P < 0.001). LASSO revealed that blood eosinophil count was the strongest predictor of interstitial eosinophilic aggregates. In the retrospective CKD cohort, higher baseline and time-updated blood eosinophil counts were significantly associated with a higher rate of KRT initiation in Cox proportional hazards models and marginal structural models.

CONCLUSIONS

Interstitial eosinophilic aggregates were associated with a higher risk of a composite of KRT initiation or ≥40% decline in eGFR.

PODCAST

This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/CJASN/2023_12_08_CJN0000000000000277.mp3.

Knock-in mice expressing a humanized arachidonic acid 15-lipoxygenase (Alox15) carry a partly dysfunctional erythropoietic system

Arachidonic acid 15-lipoxygenases (ALOX15) play a role in mammalian erythropoiesis but they have also been implicated in inflammatory processes. Seven intact Alox genes have been detected in the mouse reference genome and the mouse Alox15 gene is structurally similar to the orthologous genes of other mammals. However, mouse and human ALOX15 orthologs have different functional characteristics. Human ALOX15 converts C20 polyenoic fatty acids like arachidonic acid mainly to the n-6 hydroperoxide. In contrast, the n-9 hydroperoxide is the major oxygenation product formed by mouse Alox15. Previous experiments indicated that Leu353Phe exchange in recombinant mouse Alox15 humanized the catalytic properties of the enzyme. To investigate whether this functional humanization might also work in vivo and to characterize the functional consequences of mouse Alox15 humanization we generated Alox15 knock-in mice (Alox15-KI), in which the Alox15 gene was modified in such a way that the animals express the arachidonic acid 15-lipoxygenating Leu353Phe mutant instead of the arachidonic acid 12-lipoxygenating wildtype enzyme. These mice develop normally, they are fully fertile but display modified plasma oxylipidomes. In young individuals, the basic hematological parameters were not different when Alox15-KI mice and outbred wildtype controls were compared. However, when growing older male Alox15-KI mice develop signs of dysfunctional erythropoiesis such as reduced hematocrit, lower erythrocyte counts and attenuated hemoglobin concentration. These differences were paralleled by an improved ex vivo osmotic resistance of the peripheral red blood cells. Interestingly, such differences were not observed in female individuals suggesting gender specific effects. In summary, these data indicated that functional humanization of mouse Alox15 induces defective erythropoiesis in aged male individuals.

PATHOPHYSIOLOGICAL MECHANISMS OF DEEP VEIN THROMBOSIS

Deep venous thrombosis is a frequent multifactorial disease and most of the time is triggered by the interaction between acquired risk factors, particularly immobility, and hereditary risk factors such as thrombophilias. The mechanisms underlying deep venous thrombosis are not fully elucidated; however, in recent years the role of venous flow, endothelium, platelets, leukocytes, and the interaction between inflammation and hemostasis has been determined. Alteration of venous blood flow produces endothelial activation, favoring the adhesion of platelets and leukocytes, which, through tissue factor expression and neutrophil extracellular traps formation, contribute to the activation of coagulation, trapping more cells, such as red blood cells, monocytes, eosinophils, lymphocytes. The coagulation factor XI-driven propagation phase of blood coagulation plays a major role in venous thrombus growth, but a minor role in hemostasis. In this work, the main mechanisms involved in the pathophysiology of deep vein thrombosis are described.

Hypereosinophilia causes progressive cardiac pathologies in mice

Hypereosinophilic syndrome is a progressive disease with extensive eosinophilia that results in organ damage. Cardiac pathologies are the main reason for its high mortality rate. A better understanding of the mechanisms of eosinophil-mediated tissue damage would benefit therapeutic development. Here, we describe the cardiac pathologies that developed in a mouse model of hypereosinophilic syndrome. These IL-5 transgenic mice exhibited decreased left ventricular function at a young age which worsened with age. Mechanistically, we demonstrated infiltration of activated eosinophils into the heart tissue that led to an inflammatory environment. Gene expression signatures showed tissue damage as well as repair and remodeling processes. Cardiomyocytes from IL-5Tg mice exhibited significantly reduced contractility relative to wild type (WT) controls. This impairment may result from the inflammatory stress experienced by the cardiomyocytes and suggest that dysregulation of contractility and Ca2+ reuptake in cardiomyocytes contributes to cardiac dysfunction at the whole organ level in hypereosinophilic mice.

French guidelines for the etiological workup of eosinophilia and the management of hypereosinophilic syndromes

Eosinophilic-related clinical manifestations are protean and the underlying conditions underpinning eosinophilia are highly diverse. The etiological workup of unexplained eosinophilia/hypereosinophilia can be challenging, and can lead sometimes to extensive, inappropriate, costly and/or invasive investigations. To date, guidelines for the etiological workup and management of eosinophilia are mainly issued by hematologists, and thus mostly cover the scope of clonal hypereosinophilic syndromes (HES). Here, thanks to an extensive literature review, and thanks to the joint work of a large panel of experts involving physicians from both adult and pediatric medicine and from various subspecialties (as well as a representative of a patients' association representative), we provide recommendations for both the step-by step diagnostic workup of eosinophilia (whether unexplained or within specific contexts) as well as the management and follow-up of the full spectrum of eosinophilic disorders (including clonal, reactive, lymphocytic and idiopathic HES, as well as single-organ diseases). Didactic prescription summaries intended to facilitate the prescription of eosinophil-targeted drugs are also provided, as are practical diagnostic and therapeutic algorithms. Lastly, this set of recommendations also includes a summary intended for general practitioners, as well as an overview of the therapeutic patient education program set up by the French reference center for HES. Further updates will be mandatory as new validated information emerges.

Concurrent hypereosinophilic syndrome and deep vein thrombosis after Pfizer-BioNTech COVID-19 vaccination: A case report

Herein, we report a case of eosinophilia syndrome and deep vein thrombosis presenting concurrently after the administration of the BNT162b2 mRNA-based coronavirus disease 2019 (COVID-19) vaccine. It is extremely rare to have both hypereosinophilic syndrome and deep vein thrombosis simultaneously. Both are serious diseases and should be treated with caution.

Identifying risk and prognostic factors in polyarteritis nodosa patients with digital gangrene

BACKGROUND

Many patients with polyarteritis nodosa (PAN) complicated by digital gangrene have poor outcomes and related research information is limited. Our aim is to identify the associated risk and prognostic factors in PAN patients with digital gangrene.

PATIENTS AND METHODS

We conducted a retrospective study of 148 PAN patients admitted to Peking Union Medical College Hospital from Octorber 2001 to December 2018. Forty-seven (31.8%) PAN patients had digital gangrene. The average age was 40.4 ± 17.9 years.

RESULTS

The presence of digital gangrene was correlated with current smoking (P = .008, odds ratio [OR] 2.99, 95% CI, 1.33-6.73), eosinophil elevation (P = .003, OR 4.21, 95% CI, 1.62-10.91) and elevated leukocytes (P = .001, OR 4.26, 95% CI, 1.86-9.78). Thirty-two (68.1%) gangrene patients received methylprednisolone pulse therapy and all of these patients were treated with cyclophosphamide. Nine patients suffered irreversible organ injury and 2 died. Survival analysis showed higher serum C-reactive protein (CRP) was associated with poor prognosis in patients with gangrene (log-rank P = 0.042 and generalized Wilcoxon P = .020).

CONCLUSIONS

PAN patients with current smoking and eosinophil elevation were more prone to digital gangrene and a high serum CRP level predicted poor outcomes. The CRP level should be efficiently controlled to ensure a good prognosis.

A Review of Anti-IL-5 Therapies for Eosinophilic Granulomatosis with Polyangiitis

Eosinophilic granulomatosis with polyangiitis (EGPA), previously known as Churg-Strauss syndrome, is a systemic disorder characterized by asthma, eosinophilia, and vasculitis primarily affecting small vessels. Although this disease is classified as an anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis along with microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA), observations suggest that eosinophils play a vital role in the pathophysiology of EGPA. Therefore, biopsy specimens derived from patients with EGPA demonstrated an increase in eosinophils within the vascular lumen and extravascular interstitium, especially in patients negative for ANCA. In addition, active secretion of eosinophil intracellular components by cytolysis and piecemeal degranulation occurs in the extravascular interstitium and bloodstream. Although the treatment for EGPA is described in the context of ANCA-associated vasculitis along with MPA and GPA, a therapeutic approach to suppress eosinophils is also considered. Monoclonal antibodies directed against interleukin-5 (IL-5) or its receptors are good therapeutic agents because IL-5 plays an important role in eosinophil growth, activation, and survival. Currently, mepolizumab (Nucala), reslizumab (Cinqair), and benralizumab (Fasenra) have been studied for use in patients with EGPA. These monoclonal antibodies were initially approved for use in patients with severe eosinophilic asthma. Mepolizumab is now approved for treating EGPA following the success of phase 3 randomized controlled trial. Therefore, further studies are needed to clarify long-term safety and efficacy of anti-IL-5 agents and establish indications of individual therapeutic agents tailored to individual conditions of patients with EGPA.

Peripheral Eosinophil Count Is Associated With the Prognosis of Patients With Type B Aortic Dissection Undergoing Endovascular Aortic Repair: A Retrospective Cohort Study

Background Eosinophil count (EOS) has been proposed to provide prognostic information in multiple cardiovascular disorders. However, few researchers have investigated the predictive value of EOS for patients with type B aortic dissection who had thoracic endovascular repair. Methods and Results The authors reviewed the records of 912 patients with type B aortic dissection who were treated with thoracic endovascular repair in Changhai Hospital, Shanghai. By using receiver operating characteristic curve analysis, patients were divided into 2 groups based on the admission EOS cutoff value (<7.4×10⁶/L [n=505] and ≥7.4×10⁶/L [n=407]). To reduce selection bias, propensity score matching was applied. Multivariable regression analysis and Kaplan-Meier curves were performed to assess the association between EOS and long-term outcomes. Furthermore, we investigated nonlinear correlations between EOS and outcomes using general additive models with restricted cubic splines. In the matched population, lower EOS was associated with significantly higher 30-day mortality (4.1% vs 0%, P=0.007). There was no statistically difference in 30-day adverse events between the 2 groups (all P>0.05). Kaplan-Meier analysis revealed that patients with an EOS <7.4×10⁶/L had a higher incidence of 1-year all-cause death (7.95% vs. 2.34%, P=0.008) and aortic-related death (5.98% vs 1.81%, P=0.023) than those with higher EOS. Multivariable Cox analysis showed that continuous EOS was independently associated with 1-year mortality (hazard ratio, 3.23 [95% CI, 1.20-8.33], P=0.019). In addition, we discovered a nonlinear association between EOS and 1-year outcomes. Conclusions Lower admission EOS values predict higher short- and long-term mortality after thoracic endovascular repair.

Elevated plasma D-dimer levels in patients with anti-N-methyl-D-aspartate receptor encephalitis

PURPOSE

We aimed to explore the difference in coagulation function between healthy individuals and patients with anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis and its relationship with disease severity.

METHODS

We retrospectively compared coagulation function in 161 patients with first-attack anti-NMDAR encephalitis and 178 healthy individuals. The association between D-dimer levels and disease severity was analyzed using binary logistic regression. Receiver operating characteristic (ROC) curves were used to analyze the predictive value of D-dimer levels for the severity of anti-NMDAR encephalitis.

RESULTS

Compared to control individuals, patients with anti-NMDAR encephalitis had higher D-dimer levels (median 0.14 vs. 0.05 mg/L, p < 0.001), blood white blood cell (WBC) count (median 8.54 vs. 5.95 × 109/L, p < 0.001), and neutrophil count (median 6.14 vs. 3.1 × 109/L, p < 0.001). D-dimers (median 0.22 vs. 0.10 mg/L, p < 0.001), blood WBC count (median 9.70 vs. 7.70 × 109/L, p < 0.001), neutrophil count (median 7.50 vs. 4.80 × 109/L, p < 0.001), and C-reactive protein (median 2.61 vs. 1.50 mg/l, p = 0.017) were higher; however, eosinophils (median 0.02 vs. 0.06 × 109/L, p < 0.001), and blood calcium (median 2.26 vs. 2.31 mmol/L, p = 0.003) were lower in patients with severe forms of anti-NMDAR encephalitis than in those with mild to moderate forms, and were associated with initial modified Rankin Scale scores. Multivariate analysis showed that D-dimer levels were significantly associated with severity [odds ratio =2.631, 95% confidence interval (CI) = 1.018-6.802, p = 0.046]. The ROC curve was used to analyze the predictive value of D-dimer levels for disease severity. The area under the curve was 0.716 (95% CI = 0.64-0.80, p < 0.001), and the best cut-off value was D-dimer = 0.147 mg/L (sensitivity 0.651; specificity, 0.705).

CONCLUSION

Serum D-dimer and neutrophil levels were independent predictors of disease severity in patients with first-attack anti-NMDAR encephalitis.

At the Heart of Eosinophilic Granulomatosis with Polyangiitis: into Cardiac and Vascular Involvement

PURPOSE OF REVIEW

To provide an overview of existing literature on pathogenetic and clinical aspects of cardiac and vascular involvement in eosinophilic granulomatosis with polyangiitis (EGPA).

RECENT FINDINGS

In EGPA, cardiac and vascular involvement are more common than previously thought. However, no international recommendations on the topic are available yet. Herein, we summarize the existing evidence on the topic and propose a diagnostic approach for cardiac involvement in EGPA. The prevalence of cardiovascular involvement in patients with EGPA varies greatly among published studies, ranging between 3.1-18.7% for occlusive arterial disease, 5.8-30% for venous thrombosis and 17-92% for heart involvement. Cardiac involvement in EGPA is associated with high mortality even though manifestations are heterogeneous. In principle, every anatomical structure of the heart can be involved, and EGPA-related heart disease may be completely asymptomatic at first. A careful diagnostic work-up for early detection and prompt treatment initiation is therefore required. While cardiac manifestations are more common in anti-neutrophil cytoplasmic antibodies (ANCA)-negative patients, arterial and venous thrombotic events are not linked to ANCA status but correlate closely with disease activity and accumulate at disease onset. Thrombotic events (mainly venous) are considerably more frequent in EGPA than in the general population contributing substantially to morbidity and highlighting the importance of developing specific prevention strategies for patients who are diagnosed with EGPA.

Small intestinal resident eosinophils maintain gut homeostasis following microbial colonization

The intestine harbors a large population of resident eosinophils, yet the function of intestinal eosinophils has not been explored. Flow cytometry and whole-mount imaging identified eosinophils residing in the lamina propria along the length of the intestine prior to postnatal microbial colonization. Microscopy, transcriptomic analysis, and mass spectrometry of intestinal tissue revealed villus blunting, altered extracellular matrix, decreased epithelial cell turnover, increased gastrointestinal motility, and decreased lipid absorption in eosinophil-deficient mice. Mechanistically, intestinal epithelial cells released IL-33 in a microbiota-dependent manner, which led to eosinophil activation. The colonization of germ-free mice demonstrated that eosinophil activation in response to microbes regulated villous size alterations, macrophage maturation, epithelial barrier integrity, and intestinal transit. Collectively, our findings demonstrate a critical role for eosinophils in facilitating the mutualistic interactions between the host and microbiota and provide a rationale for the functional significance of their early life recruitment in the small intestine.

Allergic asthma is a risk factor for human cardiovascular diseases

Asthma is an allergic airway disease in which type 2-mediated inflammation has a pathogenic role. Cardiovascular diseases (CVDs) are type 1-dominant inflammatory diseases in which type 2 cytokines often have a protective role. However, clinical studies demonstrate that allergic asthma and associated allergies are essential risk factors for CVD, including coronary heart diseases, aortic diseases, peripheral arterial diseases, pulmonary embolism, right ventricular dysfunction, atrial fibrillation, cardiac hypertrophy and even hypertension. Mast cells, eosinophils, inflammatory cytokines and immunoglobulin (Ig)E accumulate in asthmatic lungs and in the injured heart and vasculature of patients with CVD. Clinical studies show that many anti-asthmatic therapies affect the risk of CVD. As such, allergic asthma and CVD may share common pathogenic mechanisms. Preclinical investigations indicate that anti-asthmatic drugs have therapeutic potential in certain CVDs. In this Review, we discuss how asthma and allied allergic conditions may contribute to the prevalence, incidence and progression of CVD and vice versa.

In vivo visualization of eosinophil secretion in eosinophilic granulomatosis with polyangiitis: An ultrastructural study

BACKGROUND

Although eosinophilic granulomatosis with polyangiitis (EGPA) has been considered as a single disease entity belonging to anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, several studies have suggested that in addition to the mechanisms associated with ANCA, those associated with eosinophils play a vital role in tissue damage. Nevertheless, the morphological bases underlying eosinophil-associated lesions have not been completely elucidated.

METHODS

We investigated the electron microscopic findings of sural nerve biopsy specimens obtained from 18 patients with EGPA by focusing on the behavior of eosinophils, particularly the mode of secretion.

RESULTS

Eosinophils tended to be located at sites close to endothelial cells within the lumina of epineurial small vessels. Attachment of eosinophils to endothelial cells was observed, particularly at the junction between neighboring endothelial cells, and some of these eosinophils appeared to escape from the vascular lumen to migrate into the extravascular interstitium. Furthermore, we observed eosinophil degranulation via piecemeal degranulation and cytolysis. Degranulating eosinophils were identified in both intravascular and extravascular compartments. Some of the small vessels appeared to be occluded by numerous eosinophils, and eosinophils attached by platelets were also observed, suggesting that coagulopathy occurs in EGPA.

CONCLUSIONS

Both extravascular and intravascular eosinophils can induce tissue damage unrelated to classical necrotizing vasculitis associated with ANCA in patients with EGPA. Further research is necessary to elucidate the molecular basis of the induction of these fine structural changes, which will contribute to the development of targeted therapies based on specific mechanisms of eosinophil-related diseases.

The aryl hydrocarbon receptor contributes to tissue adaptation of intestinal eosinophils in mice

Eosinophils are potent sources of inflammatory and toxic mediators, yet they reside in large numbers in the healthy intestine without causing tissue damage. We show here that intestinal eosinophils were specifically adapted to their environment and underwent substantial transcriptomic changes. Intestinal eosinophils upregulated genes relating to the immune response, cell-cell communication, extracellular matrix remodeling, and the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor with broad functions in intestinal homeostasis. Eosinophils from AHR-deficient mice failed to fully express the intestinal gene expression program, including extracellular matrix organization and cell junction pathways. AHR-deficient eosinophils were functionally impaired in the adhesion to and degradation of extracellular matrix, were more prone to degranulation, and had an extended life span. Lack of AHR in eosinophils had wider effects on the intestinal immune system, affecting the T cell compartment in nave and helminth-infected mice. Our study demonstrates that the response to environmental triggers via AHR partially shapes tissue adaptation of eosinophils in the small intestine.

Impacts of eosinophil percentage on prognosis acute type A aortic dissection patients

Background

Eosinophils are pro-inflammatory cells involved in thrombosis and have been proposed as a prognosis marker in acute ischemic stroke and ST-elevation myocardial Infarction. Here, we sought to clarify the prognostic value of eosinophil percentage (EOS%) in patients with acute type A aortic dissection (AAAD).

Methods

We examined 183 consecutive AAAD patients. Based on the optimum cut-off value of EOS% determined by X-tile software, patients were classified into the low EOS% (EOS% ≤ 0.1) and high EOS% groups (EOS% > 0.1). We performed multivariate regression analysis and Kaplan–Meier (KM) survival curves to assess the association between EOS% and mortality. Eosinophil accumulation in aortic dissection intraluminal thrombus was confirmed using hematoxylin–eosin (H&E) staining. An external cohort from Medical Information Mart for Intensive Care IV was performed to validate the results.

Results

Relative to surviving patients, those who died during hospitalization had significantly lower EOS% (p = 0.001) but significantly higher WBC (p = 0.002) and neutrophil (p = 0.001) counts. Multivariate regression analysis identified EOS% as an independent predictor of in-hospital and 1-year mortality. KM curves revealed that 1-year cumulative mortality was significantly higher in the low EOS% group, although it was mainly attributed to the higher 30-day mortality. H&E staining revealed massive infiltration of eosinophils in all 20 thrombus specimens. The external validation confirmed that relative to survivors, patients with in-hospital mortality (p = 0.010) had significantly lower EOS%. Moreover, multivariate regression analyses identified that decreased EOS% was independently significantly associated with in-hospital mortality.

Conclusions

Low EOS% is significantly related to increased mortality rates in AAAD patients.

The role of procoagulant phospholipids on the surface of circulating blood cells in thrombosis and haemostasis

Phospholipids (PLs) are found in all cell types and are required for structural support and cell activation signalling pathways. In resting cells, PLs are asymmetrically distributed throughout the plasma membrane with native procoagulant aminophospholipids (aPLs) being actively maintained in the inner leaflet of the membrane. Upon platelet activation, aPLs rapidly externalize to the outer leaflet and are essential for supporting the coagulation cascade by providing binding sites for factors in the cell-based model. More recent work has uncovered a role for enzymatically oxidized PLs (eoxPLs) in facilitating coagulation, working in concert with native aPLs. Despite this, the role of aPLs and eoxPLs in thrombo-inflammatory conditions, such as arterial and venous thrombosis, has not been fully elucidated. In this review, we describe the biochemical structures, distribution and regulation of aPL externalization and summarize the literature on eoxPL generation in circulating blood cells. We focus on the currently understood role of these lipids in mediating coagulation reactions in vitro, in vivo and in human thrombotic disease. Finally, we highlight gaps in our understanding in how these lipids vary in health and disease, which may place them as future therapeutic targets for the management of thrombo-inflammatory conditions.

Immunomodulating Therapies in Acute Myocarditis and Recurrent/Acute Pericarditis

The field of inflammatory disease of the heart or "cardio-immunology" is rapidly evolving due to the wider use of non-invasive diagnostic tools able to detect and monitor myocardial inflammation. In acute myocarditis, recent data on the use of immunomodulating therapies have been reported both in the setting of systemic autoimmune disorders and in the setting of isolated forms, especially in patients with specific histology (e.g., eosinophilic myocarditis) or with an arrhythmicburden. A role for immunosuppressive therapies has been also shown in severe cases of coronavirus disease 2019 (COVID-19), a condition that can be associated with cardiac injury and acute myocarditis. Furthermore, ongoing clinical trials are assessing the role of high dosage methylprednisolone in the context of acute myocarditis complicated by heart failure or fulminant presentation or the role of anakinra to treat patients with acute myocarditis excluding patients with hemodynamically unstable conditions. In addition, the explosion of immune-mediated therapies in oncology has introduced new pathophysiological entities, such as immune-checkpoint inhibitor-associated myocarditis and new basic research models to understand the interaction between the cardiac and immune systems. Here we provide a broad overview of evolving areas in cardio-immunology. We summarize the use of new imaging tools in combination with endomyocardial biopsy and laboratory parameters such as high sensitivity troponin to monitor the response to immunomodulating therapies based on recent evidence and clinical experience. Concerning pericarditis, the normal composition of pericardial fluid has been recently elucidated, allowing to assess the actual presence of inflammation; indeed, normal pericardial fluid is rich in nucleated cells, protein, albumin, LDH, at levels consistent with inflammatory exudates in other biological fluids. Importantly, recent findings showed how innate immunity plays a pivotal role in the pathogenesis of recurrent pericarditis with raised C-reactive protein, with inflammasome and IL-1 overproduction as drivers for systemic inflammatory response. In the era of tailored medicine, anti-IL-1 agents such as anakinra and rilonacept have been demonstrated highly effective in patients with recurrent pericarditis associated with an inflammatory phenotype.

New appreciation for an old pathway: the Lands Cycle moves into new arenas in health and disease

The Lands Pathway is a fundamental biochemical process named for its discovery by William EM Lands and revealed in a series of seminal papers published in the Journal of Biological Chemistry between 1958-65. It describes the selective placement in phospholipids of acyl chains, by phospholipid acyltransferases. This pathway has formed a core component of our knowledge of phospholipid and also diglyceride metabolism in mammalian tissues for over 60 years now. Our understanding of how the Lands pathways are enzymatically mediated via large families of related gene products that display both substrate and tissue specificity has grown exponentially since. Recent studies building on this are starting to reveal key roles for the Lands pathway in specific scenarios, in particular inflammation, immunity and inflammation. This review will cover the Lands cycle from historical perspectives first, then present new information on how this important cycle forms a central regulatory node connecting fatty acyl and phospholipid metabolism and how its altered regulation may present new opportunities for therapeutic intervention in human disease.

Literature reviews of stroke with hypereosinophilic syndrome

Hypereosinophilic syndrome (HES) is defined by persistently elevated blood eosinophil levels and is associated with evidence of organ damage. Cardiovascular involvement in HES is most commonly associated with Loffler endocarditis (cardiac HES). Cardiac HES is typically characterized by progressive subendocardial fibrosis with overlying mural thrombus formation, leading to restrictive dysfunction of the left ventricle. The thrombus from cardiac HES could result in cardiogenic stroke; however, most of the stroke cases with HES were not associated with huge thromboembolism rather multiple infarcts in the watershed area. The major clinical features of 97 previously reported cases of stroke with HES are as follows: the median age was 52 years, of which 61 (63%) were men; the initial presenting symptoms were neurological (73%), followed by headache (16%), respiratory symptoms (9%), and visual symptoms (9%). Almost half of the cases were diagnosed with cardiac HES. The characteristics of cardiac findings were mural thrombi, endomyocardial fibrosis, and a restrictive pattern of heart failure. Cerebral findings revealed 78 cases (80%) were described as multiple infarctions and 55 cases (57 %) were involved with watershed areas, whereas 11 cases (11％) were described as embolic stroke for one proximal large-vessel occlusion. Regarding treatment, 71 (73%), 28 (29%), and 16 (16%) patients were treated with steroids, anticoagulants, and antiplatelets, respectively. The overall mortality and recovery rates were 11% and 89%, respectively. Physicians should know most cases of stroke with HES are characterized by multiple infarctions in the watershed area, and cardiac HES is not always associated with stroke.

Hypereosinophilia with cerebral venous sinus thrombosis and intracerebral hemorrhage: A case report and review of the literature

BACKGROUND

Hypereosinophilia (HE) is defined as a peripheral blood eosinophil count of > 1.5 × 10⁹/L and may be associated with tissue damage. The clinical presentations of HE vary; however, myocardial fibrosis and thrombosis can threaten the lives of patients with sustained eosinophilia. Cerebral venous sinus thrombosis (CVST) in the setting of eosinophil-related diseases has seldom been reported. Here, we review the literature on HE with CVST to increase knowledge and encourage early diagnosis.

CASE SUMMARY

A previously healthy 41-year-old man was admitted to hospital with diarrhea and abdominal pain. He was treated with antibiotics for suspected acute colitis. Three days later, he experienced headache and vomiting. Brain computed tomography (CT) revealed thrombosis of the left jugular vein to the left transverse sinus vein. Platelet (PLT) count decreased to 60 × 10¹²/L, and absolute eosinophil count (AEC) increased to 2.41 × 10⁹/L. He was treated with low-molecular-weight heparin. PLT count progressively decreased to 14 × 10⁹/L, and we terminated anticoagulation and performed PLT transfusion. Six days after admission, he complained of a worsening headache. Brain CT revealed right temporal lobe and left centrum semiovale intracerebral hemorrhage, and AEC increased to 7.65 × 10⁹/L. We used prednisolone for HE. The level of consciousness decreased, so emergency hematoma removal and decompressive craniectomy for right cerebral hemorrhage were performed. The patient was alert 2 d after surgery. He was treated with anticoagulation again 2 wk after surgery. Corticosteroids were gradually tapered without any symptomatic recurrence or abnormal laboratory findings.

CONCLUSION

HE can induce CVST, and we need to focus on eosinophil counts in patients with CVST.

Characterization of the Structural Diversity and Structure-Specific Behavior of Oxidized Phospholipids by LC-MS/MS

Polyunsaturated fatty acids (PUFAs), esterified to phospholipids, are susceptible to oxidation. They form oxidized phospholipids (OxPLs) by oxygenases or reactive oxygen species (ROS), or both. These OxPLs are associated with various diseases, such as atherosclerosis, pulmonary injuries, neurodegenerative diseases, cancer, and diabetes. Since many types of OxPLs seem to be generated in vivo, precise determination of their structural diversity is required to understand their potential structure-specific functions. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful method to quantitatively measure the structural diversity of OxPLs present in biological samples. This review outlines recent advances in analytical methods for OxPLs and their physiological relevance in health and diseases.

FIP1L1-PDGFRA-Associated Hypereosinophilic Syndrome as a Treatable Cause of Watershed Infarction

BACKGROUND AND PURPOSE

Ischemic stroke has been reported in various conditions associated with eosinophilia. FIP1L1-PDGFRA fusion ([Fip1-like 1-platelet-derived growth factor receptor alpha]; F/P) leads to the proliferation of the eosinophilic lineage and thus to a clonal hypereosinophilic syndrome that is highly responsive to imatinib.

METHODS

We previously reported on a nationwide retrospective study of 151 patients with F/P-associated clonal hypereosinophilic syndrome. Patients from this cohort with a clinical history of ischemic stroke (as well as 2 additional cases) were further analyzed to better define their clinical picture and outcomes.

RESULTS

Sixteen male patients (median age, 51 [43-59] years) with low-to-intermediate cardiovascular risk were included. Median National Institutes of Health Stroke Scale was 4 (range, 1-6). Most cerebral imaging disclosed multiple bilateral infarctions of watershed distribution (69%). Despite frequent cardiac involvement (50%), cardiac thrombus was evidenced in a single patient and, according to the TOAST classification (Trial of ORG 10172 in Acute Stroke Treatment), 62.5% of strokes were presumably of undetermined etiology. Among the 15 patients treated with imatinib, and after a median follow-up of 4.5 years, stroke recurred in only 3 patients (consisting of either cardio embolic or hemorrhagic events, unrelated to the first episode).

CONCLUSIONS

F/P+ clonal hypereosinophilic syndrome is a diagnosis to consider in patients with unexplained ischemic stroke and hypereosinophilia (especially in the setting of multiple cortical borderzone distribution) and warrants prompt initiation of imatinib.

Eosinophil Knockout Humans: Uncovering the Role of Eosinophils Through Eosinophil-Directed Biological Therapies

The enigmatic eosinophil has emerged as an exciting component of the immune system, involved in a plethora of homeostatic and inflammatory responses. Substantial progress has been achieved through experimental systems manipulating eosinophils in vivo, initially in mice and more recently in humans. Researchers using eosinophil knockout mice have identified a contributory role for eosinophils in basal and inflammatory processes and protective immunity. Primarily fueled by the purported proinflammatory role of eosinophils in eosinophil-associated diseases, a series of anti-eosinophil therapeutics have emerged as a new class of drugs. These agents, which dramatically deplete eosinophils, provide a valuable opportunity to characterize the consequences of eosinophil knockout humans. Herein, we comparatively describe mouse and human eosinophil knockouts. We put forth the view that human eosinophils negatively contribute to a variety of diseases and, unlike mouse eosinophils, do not yet have an identified role in physiological health; thus, clarifying all roles of eosinophils remains an ongoing pursuit.

Identification of Genetic Modifiers of TDP-43: Inflammatory Activation of Astrocytes for Neuroinflammation

Transactive response DNA-binding protein 43 (TDP-43) is a ubiquitously expressed DNA/RNA-binding protein linked to amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). TDP-43 has been implicated in numerous aspects of the mRNA life cycle, as well as in cell toxicity and neuroinflammation. In this study, we used the toxicity of the TDP-43 expression in Saccharomyces cerevisiae as an assay to identify TDP-43 genetic interactions. Specifically, we transformed human TDP-43 cDNAs of wild-type or disease-associated mutants (M337V and Q331K) en masse into 4653 homozygous diploid yeast deletion mutants and then used next-generation sequencing readouts of growth to identify yeast toxicity modifiers. Genetic interaction analysis provided a global view of TDP-43 pathways, some of which are known to be involved in cellular metabolic processes. Selected putative loci with the potential of genetic interactions with TDP-43 were assessed for associations with neurotoxicity and inflammatory activation of astrocytes. The pharmacological inhibition of succinate dehydrogenase flavoprotein subunit A (SDHA) and voltage-dependent anion-selective channel 3 (VDAC3) suppressed TDP-43-induced expression of proinflammatory cytokines in astrocytes, indicating the critical roles played by SDHA and VDAC3 in TDP-43 pathways during inflammatory activation of astrocytes and neuroinflammation. Thus, the findings of our TDP-43 genetic interaction screen provide a global landscape of TDP-43 pathways and may help improve our understanding of the roles of glia and neuroinflammation in ALS and FTD pathogenesis.

Venous thrombosis and predictors of relapse in eosinophil-related diseases

Eosinophils have widespread procoagulant effects. Eosinophilic cardiovascular toxicity mostly consists of endomyocardial damage or eosinophilic vasculitis, while reported cases of venous thrombosis (VT) are scarce. We aimed to report on the clinical features and treatment outcomes of patients with unexplained VT and eosinophilia, and to identify predictors of relapse. This retrospective, multicenter, observational study included patients aged over 15 years with VT, concomitant blood eosinophilia ≥ 1G/L and without any other moderate-to-strong contributing factors for VT. Fifty-four patients were included. VT was the initial manifestation of eosinophil-related disease in 29 (54%) patients and included pulmonary embolism (52%), deep venous thrombosis (37%), hepatic (11%) and portal vein (9%) thromboses. The median [IQR] absolute eosinophil count at VT onset was 3.3G/L [1.6-7.4]. Underlying eosinophil-related diseases included FIP1L1-PDGFRA-associated chronic myeloid neoplasm (n = 4), Eosinophilic Granulomatosis with Polyangiitis (n = 9), lymphocytic (n = 1) and idiopathic (n = 29) variants of hypereosinophilic syndrome. After a median [IQR] follow-up of 24 [10-62] months, 7 (13%) patients had a recurrence of VT. In multivariate analysis, persistent eosinophilia was the sole variable associated with a shorter time to VT relapse (HR 7.48; CI95% [1.94-29.47]; p = 0.015). Long-term normalization of eosinophil count could prevent the recurrence of VT in a subset of patients with unexplained VT and eosinophilia ≥ 1G/L.

Thrombotic, Vascular, and Bleeding Complications of the Myeloproliferative Neoplasms

Thrombotic, vascular, and bleeding complications are the most frequent causes of morbidity and mortality in myeloproliferative neoplasms (MPNs). The interplay and reciprocal amplification between two factors are considered to lead to thrombosis in MPNs: (1) circulating blood cell-intrinsic abnormalities caused by an MPN driver mutation in their hematopoietic progenitor/stem cells, interacting with vascular endothelial cells, show prothrombotic and proadhesive phenotypes; and (2) a state of usually subclinical systemic inflammation that fuels the thrombotic tendency. Prevention and treatment require maintenance of hematocrit less than 45% and cytoreductive therapy in patients with a high risk for thrombotic and vascular complications.

Eosinophilic Granulomatosis With Polyangiitis: Dissecting the Pathophysiology

Eosinophilic Granulomatosis with Polyangiitis (EGPA) is a rare multisystemic disease classified both amongst hypereosinophilic disorders and ANCA-associated vasculitis. Vessel inflammation and eosinophilic proliferation are the hallmarks of the disease and main effectors of organ damage. Two distinct disease phenotypes have classically been described according to ANCA-status: the ANCA-negative subset with eosinophil-driven manifestation and the ANCA-positive one with vasculitic manifestations. An analogous dichotomization has also been backed by histological findings and a distinct genetic background. EGPA is typically consider a Th2-mediated disease and blood and tissue eosinophilia represent the cornerstone of diagnosis. Besides, ANCA are known for inducing endothelial injury and vascular inflammation by activating the circulating neutrophils. Thus, the pathogenesis of EGPA seems to be mediated by two coexisting mechanisms. However, the verbatim application of this strict dualism cannot always be translated into routine clinical practice. In the present review we describe the current knowledge on the eosinophilic and ANCA-mediated aspects of EGPA pathogenesis. Finally, we review the rationale of the currently proposed EGPA dichotomy and future research perspectives.

Basophil Blood Cell Count Is Associated With Enhanced Factor II Plasma Coagulant Activity and Increased Risk of Mortality in Patients With Stable Coronary Artery Disease: Not Only Neutrophils as Prognostic Marker in Ischemic Heart Disease

Background White blood cell count, which is inexpensive and widely available in clinical practice, has been proposed to provide prognostic information in coronary artery disease (CAD). Elevated levels of white blood cell subtypes may play different roles in atherothrombosis and predict cardiovascular outcomes. Methods and Results The association between white blood cell counts and mortality was evaluated in 823 subjects with angiographically demonstrated and clinically stable CAD in an observational-longitudinal study. The correlation among white blood cell counts and factor II plasma coagulant activity was analyzed in 750 subjects (554 CAD and 196 CAD-free) not taking anticoagulant drugs. Subjects with overt leukocytosis or leukopenia were excluded. In the longitudinal study after a median follow-up of 61 months, 160 (19.4%) subjects died, 107 (13.0%) of whom from cardiovascular causes. High levels of neutrophils, monocytes, eosinophils, and basophils were associated with an increased mortality rate. In multiadjusted Cox regression models, only neutrophils and basophils remained predictors of total and cardiovascular mortality. The associations remained significant after adjustment for traditional cardiovascular risk factors and by including D-dimer and the chemokine CXCL12 in the regression models. Neutrophils and basophils were also significant predictors of factor II plasma coagulant activity variability after adjustment for blood cell counts, age, sex, inflammatory markers, CAD diagnosis, and prothrombin G20210A polymorphism. Factor II plasma coagulant activity was similarly increased in subjects with high neutrophil and basophil counts and in carriers of the prothrombin 20210A allele. Conclusions Both high neutrophil and basophil blood counts may predict mortality in patients with clinically stable CAD and are associated with enhanced factor II plasma coagulant activity, thereby suggesting underlying prothrombotic mechanisms.

High Eosinophil Rates in Patients With Right-to-Left Shunts: An Expected Role, or an Unexpected Risk?

Background and objective Eosinophils are associated with thromboembolic events. Since eosinophils are eliminated in the pulmonary vasculature, right-to-left shunt (RLS) through patent foramen ovale may increase eosinophils in the peripheral blood. In this report, we evaluated the eosinophils of patients with regard to the presence of RLS and its quantity. Patients and methods In this retrospective observational study, we analyzed the complete blood cell count (CBC) of patients with RLS (n=47) and without RLS (n=31) diagnosed by contrast echocardiography (CE). RLS was identified as mild (5-10 bubbles) and moderate shunt (10-25 bubbles). Results Age and CBC were not significantly different between the groups, with the exception of eosinophils. Patients with RLS had higher eosinophils percentage compared to patients without RLS (3.1 ±1.5 vs. 1.7 ±0.7, p=0.001). Additionally, eosinophils percentage was significantly higher in the mild RLS group (2.4 ±0.9 vs. 1.7 ±0.7, p=0.016) and the moderate RLS group (4.3 ±1.6 vs. 1.7 ±0.7, p=0.001) compared to normal subjects. Also, it was significantly higher in the moderate RLS group compared to the mild group (4.3 ±1.6 vs. 2.4 ±0.9, p=0.001). Conclusions Eosinophils percentage was higher in patients with mild and moderate RLS compared to normal individuals. Moreover, the eosinophil rate was higher in patients with moderate RLS than in patients with mild RLS.