Eosinophils: biological properties and role in health and disease

Allergic hyper-carcinoembryonic antigen syndrome: A syndrome summarized by case series

Allergic respiratory diseases can increase serum carcinoembryonic antigen levels. We report three cases experiencing allergic symptoms that proved refractory to inhaled corticosteroids but exhibited a positive response to long-term treatment with oral corticosteroids. This response was characterized by a synchronous alteration in serum eosinophil counts and carcinoembryonic antigen levels. Immunofluorescence assays indicated localized carcinoembryonic antigen production within eosinophils. In addition, we conducted a systematic review of patients exhibiting similar characteristics on PubMed. After comprehensively reviewing this unique pathophysiological condition, we herein introduced a novel term "Allergic hyper-carcinoembryonic antigen syndrome," defined by the following criteria: (1) recurrent asthmatic attacks; (2) eosinophilia or pulmonary eosinophilic infiltrations accompanied by elevated serum carcinoembryonic antigen levels; (3) pulmonary lesions determined by imaging or biopsy; (4) exclusion of malignancy and infections; and (5) responsive to systemic corticosteroids. Allergic hyper-carcinoembryonic antigen syndrome suggests systemic corticosteroids should be introduced early when managing allergic patients with both eosinophilia and elevated serum carcinoembryonic antigen levels.

Dietary L-carnitine supplementation modifies blood parameters of mid-lactating dairy cows during standardized lipopolysaccharide-induced inflammation

L-carnitine, available as feed additive, is essential for the beta-oxidation of free fatty acids in the mitochondrial matrix. It provides energy to immune cells and may positively impact the functionality of leukocytes during the acute phase response, a situation of high energy demand. To test this hypothesis, German Holstein cows were assigned to a control group (CON, n = 26) and an L-carnitine supplemented group (CAR, n = 27, rumen-protected L-carnitine product: 125 g/cow/d, corresponded to total L-carnitine intake: 25 g/cow/d, supplied with concentrate) and received an intravenous bolus injection of lipopolysaccharides (LPS, 0.5 µg/kg body weight, E. coli) on day 111 postpartum as a model of standardized systemic inflammation. Blood samples were collected from day 1 ante injectionem until day 14 post injectionem (pi), with frequent sampling through an indwelling venous catheter from 0.5 h pi to 12 h pi. All parameters of the white blood cell count responded significantly to LPS, while only a few parameters were affected by L-carnitine supplementation. The mean eosinophil count, as well as the percentage of basophils were significantly higher in CAR than in CON over time, which may be due to an increased membrane stability. However, phagocytosis and production of reactive oxygen species by leukocytes remained unchanged following L-carnitine supplementation. In conclusion, although supplementation with 25 g L-carnitine per cow and day resulted in increased proportions of specific leukocyte populations, it had only minor effects on the functional parameters studied in mid-lactating dairy cows during LPS-induced inflammation, and there was no evidence of direct improvement of immune functionality.

Eosinophilic granulocytes as a potential prognostic marker for cancer progression and therapeutic response in malignant melanoma

The importance of eosinophilic granulocytes in cancer has been widely discussed in recent years. The current study reviews the evidence on the role of eosinophilic granulocytes in melanoma as a prognostic marker for cancer progression and the efficacy of treatment with modern immune checkpoint inhibitors. A total of 33 human clinical studies were included in the review, with heterogeneous data due to differences in patients populations, study design and inclusion of small study groups. However, 28 of the 33 studies suggested that eosinophilic granulocytes could be used as a prognostic biomarker for outcome and/or potential response to systemic treatment and/or occurrence of adverse events in melanoma patients. Nevertheless, the exact role of eosinophils remains to be elucidated. Further prospective, larger and better controlled studies are warranted to clarify the significance of eosinophilic granulocytes in patients with melanoma, in more details.

Using Deep Learning to Automate Eosinophil Counting in Pediatric Ulcerative Colitis Histopathological Images

Background

Accurate identification of inflammatory cells from mucosal histopathology images is important in diagnosing ulcerative colitis. The identification of eosinophils in the colonic mucosa has been associated with disease course. Cell counting is not only time-consuming but can also be subjective to human biases. In this study we developed an automatic eosinophilic cell counting tool from mucosal histopathology images, using deep learning.

Method

Four pediatric IBD pathologists from two North American pediatric hospitals annotated 530 crops from 143 standard-of-care hematoxylin and eosin (H & E) rectal mucosal biopsies. A 305/75 split was used for training/validation to develop and optimize a U-Net based deep learning model, and 150 crops were used as a test set. The U-Net model was then compared to SAU-Net, a state-of-the-art U-Net variant. We undertook post-processing steps, namely, (1) the pixel-level probability threshold, (2) the minimum number of clustered pixels to designate a cell, and (3) the connectivity. Experiments were run to optimize model parameters using AUROC and cross-entropy loss as the performance metrics.

Results

The F1-score was 0.86 (95%CI:0.79-0.91) (Precision: 0.77 (95%CI:0.70-0.83), Recall: 0.96 (95%CI:0.93-0.99)) to identify eosinophils as compared to an F1-score of 0.2 (95%CI:0.13-0.26) for SAU-Net (Precision: 0.38 (95%CI:0.31-0.46), Recall: 0.13 (95%CI:0.08-0.19)). The inter-rater reliability was 0.96 (95%CI:0.93-0.97). The correlation between two pathologists and the algorithm was 0.89 (95%CI:0.82-0.94) and 0.88 (95%CI:0.80-0.94) respectively.

Conclusion

Our results indicate that deep learning-based automated eosinophilic cell counting can obtain a robust level of accuracy with a high degree of concordance with manual expert annotations.

In-Depth Review of Loeffler Endocarditis: What Have We Learned?

Loeffler endocarditis, eosinophilic endocarditis or eosinophilic endomyocardial disease are conditions associated with hypereosinophilia and they affect the heart function. Loeffler endocarditis is a rare endomyocardial disorder thought to be caused by eosinophilic damage. The disorder is characterized by inflammatory infiltration, formation of thrombus within cardiovascular system, and ultimately fibrosis of the afflicted area. It can lead to multiple severe complications, including thromboembolic disease, thickening of fibrous tissue in the endocardium of ventricles, valve involvement, apical obliteration, and various heart disorders. Although early clinical intervention can lead to remission, the underlying mechanisms of the disorder remain unresolved. In the present article, we summarise the existing literature concerning Loeffler endocarditis based on PubMed, Web of Science, and other medical databases to conduct an in-depth review of the epidemiology, etiology, pathophysiological mechanisms, staging, diagnosis, treatment and prognosis of Loeffler endocarditis. Meanwhile, we provide novel patients data and clinical figures of Loeffler endocarditis to supplement the understanding of this cardiac disorder. The findings presented in this article provide a basis for further studies and can be used to improve management of the disorder.

Value of Absolute Eosinophil Count in Patients with Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention

Background and Aims

Elevated eosinophils typically indicate hypersensitive inflammation; however, their involvement in cardiovascular events remains incompletely understood. We investigated the association between the absolute eosinophil count (AEC) and major adverse cardiovascular and cerebrovascular events (MACCEs) in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). Additionally, we determine whether the integration of AEC with the SYNTAX II score could improve predictive ability.

Methods and Results

The AECs of 1711 patients with ACS undergoing PCI from June 2016 to November 2017 were analyzed on admission. All recruitments were splitted into three groups based on AEC tertiles and 101 participants underwent one or more noteworthy outcomings. The association between AEC and MACCEs (defined as a composite of cardiovascular death, myocardial infarction [MI], and stroke) was tested by Cox proportional-hazards regression analysis. After adjusting for confounders, AEC was independently associated with MACCEs (HR 11.555, 95% CI: 3.318-40.239). Patients in the lowest AEC tertile (T1) as a reference, those in the higher tertiles had an incrementally higher risk of MACCEs (T3: HR 1.848 95% CI: 1.157-2.952; P for trend=0.008). Inclusion of AEC enhanced the predictive accuracy of the SYNTAX II score for MACCEs (AUC: from 0.701 [95% CI: 0.646-0.756] to 0.728 [95% CI: 0.677-0.780]; DeLong's test, P = 0.020).

Conclusion

AEC is independently linked to MACCEs in ACS patients who underwent PCI, and adds incremental predictive information to the SYNTAX II score.

The role of mitochondria in eosinophil function: implications for severe asthma pathogenesis

Mitochondria are key metabolic hubs involved in cellular energy production and biosynthesis. ATP is generated primarily by glucose and fatty acid oxidation through the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) in the mitochondria. During OXPHOS there is also production of reactive oxygen species (ROS), which are involved in the regulation of cellular function. Mitochondria are also central in the regulating cell survival and death, particularly in the intrinsic apoptosis pathway. Severe asthma is a heterogeneous disease driven by various immune mechanisms. Severe eosinophilic asthma entails a type 2 inflammatory response and peripheral and lung eosinophilia, associated with severe airflow obstruction, frequent exacerbations and poor response to treatment. Mitochondrial dysfunction and altered metabolism have been observed in airway epithelial and smooth muscle cells from patients with asthma. However, the role of mitochondria in the development of eosinophilia and eosinophil-mediated inflammation in severe asthma is unknown. In this review, we discuss the currently limited literature on the role of mitochondria in eosinophil function and how it is regulated by asthma-relevant cytokines, including interleukin (IL)-5 and granulocyte-macrophage colony-stimulating factor (GM-CSF), as well as by corticosteroid drugs. Moreover, we summarise the evidence on the role of mitochondria in the regulation of eosinophils apoptosis and eosinophil extracellular trap formation. Finally, we discuss the possible role of altered mitochondrial function in eosinophil dysfunction in severe asthma and suggest possible research avenues in order to better understand their role in disease pathogenesis, and identify novel therapeutic targets.

Monotropein Alleviates Ovalbumin-Induced Asthma in Mouse Model by Inhibiting AKT/NF-κB Pathway

INTRODUCTION

Clinical management of asthma remains as a prevalent challenge. Monotropein (MON) is a naturally occurring cyclic enol ether terpene glycoside with medical application potential. This study aims to evaluate the potential therapeutic effects of MON in the mouse model of chronic asthma.

METHODS

An ovalbumin (OVA)-induced asthmatic mouse model was established to evaluate the therapeutic effect of MON at different doses (20, 40, and 80 mg/kg). The potential involvement of protein kinase B (AKT)/nuclear factor kappa B (NF-κB) pathway in the effect of MON was investigated by the administration of an AKT activator SC79. Histological changes in pulmonary tissues were examined by hematoxylin and eosin staining. The profiles of inflammatory cytokines (interleukin [IL]-4, IL-5, IL-13, and tumor necrosis factor [TNF]-α) in bronchoalveolar lavage fluid (BALF), and OVA-specific IgE in blood samples were analyzed by enzyme-linked immunosorbent assay (ELISA). The oxidative stress in the lung tissues was determined by measuring malondialdehyde level. The phosphorylation activation of AKT and NF-κB was examined by immunoblotting in the lung tissues.

RESULTS

MON treatment suppressed the infiltration of inflammatory cells in the airways of OVA-induced asthma mice and reduced the thickness of the bronchial wall and smooth muscle layer in a dose-dependent manner. MON treatment also reduced the levels of OVA-specific IgE in serum and cytokines in BALF in asthma-induced mice, and attenuated the oxidative stress in the lung tissues. OVA induced the phosphorylation of AKT and NF-κB proteins in the lung tissues of asthmatic mice, which was significantly suppressed by MON treatment. The co-administration of AKT activator SC79 impaired the therapeutic effect of MON on asthma-induced mice.

CONCLUSION

Our data demonstrated the potential therapeutic effect of MON on asthmatic mouse model, suggesting that MON attenuated the inflammatory and oxidative damages in ling tissues by dampening the AKT/NF-κB signaling pathway.

Src homology 2-B adapter protein 3 C784 T and Methylenetetrahydrofolate reductase C677 T Polymorphisms and Inflammation Markers in ST-segment Elevation Myocardial Infarction Patients

Neutrophil-lymphocyte (NLR), platelet-lymphocyte (PLR), eosinophil-lymphocyte (ELR), and monocyte-lymphocyte (MLR) ratios are systemic inflammatory markers related to myocardial infarction. The aim of this study is to investigate the association of Src homology 2-B adapter protein 3 (SH2B3) C784 T and methylenetetrahydrofolate reductase (MTHFR) C677 T polymorphisms (SNP) with systemic inflammatory markers and the severity of coronary artery disease (CAD) in 150 ST-elevation myocardial infarction (STEMI) patients. Single nucleotide polymorphisms were genotyped using the tetra-primer amplification refractory mutation system-polymerase chain reaction (T-ARMS-PCR) method. The inflammatory markers were calculated. An interventional cardiologist blinded to other data assessed the SYNTAX (SX) Score. Eosinophil and platelet counts were significantly higher in SH2B3 variants than in the wild type. Additionally, SH2B3 variants had significantly higher ELR than the wild type (.12 ± .19 vs .25 ± .34, p = .018). NLR, PLR, ELR, and MLR were considerably higher in MTHFR variants than in the wild type (p < .05). The SX score was significantly higher in both SH2B3 C784 T (21.24 ± 8.90 vs 15.29 ± 9.40, p = .00) and MTHFR C677 T (20.34 ± 10.21 vs 16.08 ± 8.39, p = .00) variants when compared with wild type. In conclusion, these polymorphisms are associated with several markers of systemic inflammation as well as the severity of CAD.

Immunofluorescence analysis of human eosinophils

A prominent inflammatory cell type in allergic diseases is the eosinophil, a granulated white blood cell that releases pro-inflammatory cytokines. Eosinophil-derived cytokines, including interleukin-9 (IL-9) and interleukin-13 (IL-13), can skew the immune response towards an allergic phenotype. Unfortunately, it is challenging to immunolabel and collect quantifiable images of eosinophils given their innate autofluorescence and ability to nonspecifically bind to antibodies. Hence, it is important to optimize permeabilization, blocking, and imaging conditions for eosinophils. Here, we show enhanced protocols to ensure that measured immunofluorescence represents specific immunolabelling. To test this, eosinophils were purified from human blood, adhered to glass coverslips, stimulated with or without platelet-activating factor (PAF), fixed with paraformaldehyde, and then permeabilized with Triton X-100 or saponin. Cells were then blocked with goat serum or human serum and incubated with antibodies labelling cytokines (IL-9 and IL-13) and secretory organelles (CD63 for crystalloid granules and transferrin receptor [TfnRc] for recycling endosomes). Carefully selected isotype controls were used throughout, and cells were imaged using Deltavision super-resolution microscopy. Intensities of fluorescent probes were quantified using Volocity software. Our findings show that permeabilization with saponin, blockage with human serum, and using concentrations of antibodies up to 10 μg/ml allowed us to detect marked differences in fluorescence intensities between isotypes and test antibodies. With the achievement of sufficient qualitative and quantitative measures of increased test probe intensity compared to respective isotypes, these results indicate that our protocol allows for optimal immunolabelling of eosinophils. Using this protocol, future studies may provide further insights into trafficking mechanisms within this important inflammatory cell type.

Staphylococcus aureus proteases trigger eosinophil-mediated skin inflammation

Staphylococcus aureus skin colonization and eosinophil infiltration are associated with many inflammatory skin disorders, including atopic dermatitis, bullous pemphigoid, Netherton's syndrome, and prurigo nodularis. However, whether there is a relationship between S. aureus and eosinophils and how this interaction influences skin inflammation is largely undefined. We show in a preclinical mouse model that S. aureus epicutaneous exposure induced eosinophil-recruiting chemokines and eosinophil infiltration into the skin. Remarkably, we found that eosinophils had a comparable contribution to the skin inflammation as T cells, in a manner dependent on eosinophil-derived IL-17A and IL-17F production. Importantly, IL-36R signaling induced CCL7-mediated eosinophil recruitment to the inflamed skin. Last, S. aureus proteases induced IL-36α expression in keratinocytes, which promoted infiltration of IL-17-producing eosinophils. Collectively, we uncovered a mechanism for S. aureus proteases to trigger eosinophil-mediated skin inflammation, which has implications in the pathogenesis of inflammatory skin diseases.

Human uterine natural killer cells regulate differentiation of extravillous trophoblast early in pregnancy

In humans, balanced invasion of trophoblast cells into the uterine mucosa, the decidua, is critical for successful pregnancy. Evidence suggests that this process is regulated by uterine natural killer (uNK) cells, but how they influence reproductive outcomes is unclear. Here, we used our trophoblast organoids and primary tissue samples to determine how uNK cells affect placentation. By locating potential interaction axes between trophoblast and uNK cells using single-cell transcriptomics and in vitro modeling of these interactions in organoids, we identify a uNK cell-derived cytokine signal that promotes trophoblast differentiation at the late stage of the invasive pathway. Moreover, it affects transcriptional programs involved in regulating blood flow, nutrients, and inflammatory and adaptive immune responses, as well as gene signatures associated with disorders of pregnancy such as pre-eclampsia. Our findings suggest mechanisms on how optimal immunological interactions between uNK cells and trophoblast enhance reproductive success.

Eosinophilic Patterns in Patients with Seasonal Allergy Affected by Bronchial Asthma and Rhinitis/Rhinosinusitis: Efficacy of Benralizumab in Patients with the Persistent Pattern

BACKGROUND

Eosinophilia can be influenced by multiple factors. This study aims to set a protocol for monitoring blood absolute eosinophil count (AEC) in patients with seasonal allergy affected by bronchial asthma (BA), allergic rhinitis (AR), or chronic rhinosinusitis with or without nasal polyposis (CRSw/sNP).

METHODS

We planned a total of four annual blood samples to measure AEC in- and out-seasonal pollen exposure (i.e., one measurement every three months for one year).

RESULTS

We identified two distinct groups of patients (non-eosinophilic and eosinophilic). Patients in the eosinophilic group presented with four different patterns (episodic, transient, floating, and persistent). Most patients with episodic, transient, and floating patterns were affected by mild allergy and the increase in eosinophils was related to allergen exposure. In contrast, patients with the persistent pattern mostly presented with more severe allergy (i.e., severe BA and relapsing CRSwNP) and the eosinophilia was unrelated to allergen exposure. The subgroup of patients with severe BA, relapsing CRSwNP, and persistent eosinophilc pattern were treated with benralizumab, which induced a noteworthy improvement in both severe BA and CRSwNP.

CONCLUSIONS

Multiple AEC measurements in patients with seasonal allergy can better reflect patient's eosinophilic status and help define the relationship of AEC enhancement with allergen exposure.

The Importance of Th2 Immune Responses in Mediating the Progression of Gastritis-Associated Metaplasia to Gastric Cancer

Gastric cancer is one of the leading causes of cancer deaths worldwide, with chronic gastritis representing the main predisposing factor initiating the cascade of events leading to metaplasia and eventually progressing to cancer. A widely accepted classification distinguishes between autoimmune and environmental atrophic gastritis, mediated, respectively, by T cells promoting the destruction of the oxyntic mucosa, and chronic H. pylori infection, which has also been identified as the major risk factor for gastric cancer. The original dogma posits Th1 immunity as a main causal factor for developing gastritis and metaplasia. Recently, however, it has become evident that Th2 immune responses play a major role in the events causing chronic inflammation leading to tumorigenesis, and in this context, many different cell types and cytokines are involved. In particular, the activity of cytokines, such as IL-33 and IL-13, and cell types, such as mast cells, M2 macrophages and eosinophils, are intertwined in the process, promoting chronic gastritis-dependent and more diffuse metaplasia. Herein, we provide an overview of the critical events driving the pathology of this disease, focusing on the most recent findings regarding the importance of Th2 immunity in gastritis and gastric metaplasia.

Causal association between genetically predicted circulating immune cell counts and frailty: a two-sample Mendelian randomization study

Background

Despite the recognized link between immune responses and frailty, the association between immune cell counts and frailty based on previous observational studies remains disputed, with uncertain causal nexus. This study aimed to elucidate causal association between genetically predicted circulating immune cell counts and frailty.

Methods

We conducted the two-sample Mendelian randomization (MR) study with independent genetic variants associated with six immune cell subtype counts from genome-wide association studies in 563,946 European individuals. Frailty summary data, assessed via frailty index (FI), was obtained from study comprising 175,226 subjects. Univariate MR, reverse MR and multivariate MR were conducted to comprehensive investigate the association between immune cell counts and FI, with two-step MR analysis for mediation analysis.

Results

Univariate MR evidence indicated that among six leukocyte subtype counts, only elevated eosinophil count was significantly correlated with higher FI (β = 0.059, 95% confidence interval [CI], 0.042-0.078, P=5.63E-11), with no reverse causal relationship identified in reverse MR. In multivariate MR, the causal effect of eosinophil count retained statistical significance (β = 0.063, 95% CI, 0.021-0.104, P = 0.003). Ultimately, the two-step MR analysis demonstrated two mediators in this causal pathway: asthma (β= 0.019, 95% CI, 0.013-0.025, P = 35.84E-10, mediated proportion, 31.732%) and rheumatoid arthritis (β= 0.004, 95% CI, 0.001-0.006, P=1.75E-03, mediated proportion, 6.411%).

Conclusions

Within immune cell subtypes, MR evidence indicated only genetically predicted circulating eosinophil count had irreversible and independent causal effect on frailty, with asthma and rheumatoid arthritis possibly serving as partial mediators. The finding stressed the need for further exploring physiological functions of eosinophils in order to develop effective strategies against frailty.

Long-term prognosis and its associated predictive factors in patients with eosinophilic gastroenteritis

BACKGROUND

Eosinophilic gastroenteritis (EGE) is a chronic recurrent disease with abnormal eosinophilic infiltration in the gastrointestinal tract. Glucocorticoids remain the most common treatment method. However, disease relapse and glucocorticoid dependence remain notable problems. To date, few studies have illuminated the prognosis of EGE and risk factors for disease relapse.

AIM

To describe the clinical characteristics of EGE and possible predictive factors for disease relapse based on long-term follow-up.

METHODS

This was a retrospective cohort study of 55 patients diagnosed with EGE admitted to one medical center between 2013 and 2022. Clinical records were collected and analyzed. Kaplan-Meier curves and log-rank tests were conducted to reveal the risk factors for long-term relapse-free survival (RFS).

RESULTS

EGE showed a median onset age of 38 years and a slight female predominance (56.4%). The main clinical symptoms were abdominal pain (89.1%), diarrhea (61.8%), nausea (52.7%), distension (49.1%) and vomiting (47.3%). Forty-three (78.2%) patients received glucocorticoid treatment, and compared with patients without glucocorticoid treatments, they were more likely to have elevated serum immunoglobin E (IgE) (86.8% vs 50.0%, P = 0.022) and descending duodenal involvement (62.8% vs 27.3%, P = 0.046) at diagnosis. With a median follow-up of 67 mo, all patients survived, and 56.4% had at least one relapse. Six variables at baseline might have been associated with the overall RFS rate, including age at diagnosis < 40 years [hazard ratio (HR) 2.0408, 95% confidence interval (CI): 1.0082-4.1312, P = 0.044], body mass index (BMI) > 24 kg/m2 (HR 0.3922, 95%CI: 0.1916-0.8027, P = 0.014), disease duration from symptom onset to diagnosis > 3.5 mo (HR 2.4725, 95%CI: 1.220-5.0110, P = 0.011), vomiting (HR 3.1259, 95%CI: 1.5246-6.4093, P = 0.001), total serum IgE > 300 KU/L at diagnosis (HR 0.2773, 95%CI: 0.1204-0.6384, P = 0.022) and glucocorticoid treatment (HR 6.1434, 95%CI: 2.8446-13.2676, P = 0.003).

CONCLUSION

In patients with EGE, younger onset age, longer disease course, vomiting and glucocorticoid treatment were risk factors for disease relapse, whereas higher BMI and total IgE level at baseline were protective.

Eosinophils at diagnosis are elevated in amyotrophic lateral sclerosis

Introduction

Amyotrophic lateral sclerosis (ALS) is a rare, devastating neurodegenerative disease that affects upper and lower motor neurons. To date, no effective treatment or reliable biomarker for ALS has been developed. In recent years, many factors have been proposed as possible biomarkers of ALS; however, no consensus has been reached. Therefore, a reliable biomarker is urgently needed. Eosinophils may play a crucial role in healthy humans and diseases, and serve as a biomarker for many chronic diseases.

Methods

Routine blood test results were collected from 66 healthy controls and 59 patients with ALS. The percentages and total numbers of each cell population were analyzed, and the correlation between these indicators and patient ALS functional rating scale-revised (ALSFRS-R) score or disease progression rate (ΔFS score) was analyzed.

Results

Compared to healthy controls, the number of blood leukocytes, neutrophils, monocytes, and basophils was significantly decreased in patients with ALS (p = 0.002, p = 0.001, p = 0.049, and p < 0.0001, respectively). There was an increase in the number of eosinophils (p < 0.0001), but no difference in the number of lymphocytes between patients with ALS and healthy controls was found (p = 0.563). Compared to healthy controls, the percentage of neutrophils was decreased and the percentage of lymphocytes and eosinophils was increased in patients with ALS (p = 0.01, p = 0.012, and p = 0.001, respectively). There was no difference between patients with ALS and healthy controls in the percentage of monocytes and basophils (p = 0.622 and p = 0.09, respectively). However, only the percentage and number of eosinophils had a correlation with the ΔFS score. Further multivariate analysis revealed a significant correlation between the disease duration, eosinophil count and percentage, and the disease progression rate (p < 0.0001, p = 0.048, and p = 0.023, respectively). The neutrophil-to-eosinophil ratio (NER), lymphocyte-to-eosinophil ratio (LER), and monocyte-to-eosinophil ratio (MER) were significantly lower in patients with ALS than in healthy controls. However, only the LER was significantly correlated with the ΔFS score.

Conclusion

These observations implicate neutrophils, lymphocytes, and eosinophils as important factors, and increasing eosinophil counts were negatively correlated with the ΔFS score in patients with ALS.

Eosinophils-from cradle to grave: An EAACI task force paper on new molecular insights and clinical functions of eosinophils and the clinical effects of targeted eosinophil depletion

Over the past years, eosinophils have become a focus of scientific interest, especially in the context of their recently uncovered functions (e.g. antiviral, anti-inflammatory, regulatory). These versatile cells display both beneficial and detrimental activities under various physiological and pathological conditions. Eosinophils are involved in the pathogenesis of many diseases which can be classified into primary (clonal) and secondary (reactive) disorders and idiopathic (hyper)eosinophilic syndromes. Depending on the biological specimen, the eosinophil count in different body compartments may serve as a biomarker reflecting the underlying pathophysiology and/or activity of distinct diseases and as a therapy-driving (predictive) and monitoring tool. Personalized selection of an appropriate therapeutic strategy directly or indirectly targeting the increased number and/or activity of eosinophils should be based on the understanding of eosinophil homeostasis including their interactions with other immune and non-immune cells within different body compartments. Hence, restoring as well as maintaining homeostasis within an individual's eosinophil pool is a goal of both specific and non-specific eosinophil-targeting therapies. Despite the overall favourable safety profile of the currently available anti-eosinophil biologics, the effect of eosinophil depletion should be monitored from the perspective of possible unwanted consequences.

Posttranslational modification and heme cavity architecture of human eosinophil peroxidase-insights from first crystal structure and biochemical characterization

Eosinophil peroxidase (EPO) is the most abundant granule protein exocytosed by eosinophils, specialized human phagocytes. Released EPO catalyzes the formation of reactive oxidants from bromide, thiocyanate, and nitrite that kill tissue-invading parasites. However, EPO also plays a deleterious role in inflammatory diseases, making it a potential pharmacological target. A major hurdle is the high similarity to the homologous myeloperoxidase (MPO), which requires a detailed understanding of the small structural differences that can be used to increase the specificity of the inhibitors. Here, we present the first crystal structure of mature leukocyte EPO at 1.6 Å resolution together with analyses of its posttranslational modifications and biochemical properties. EPO has an exceptionally high number of positively charged surface patches but only two occupied glycosylation sites. The crystal structure further revealed the existence of a light (L) and heavy (H) chain as a result of proteolytic cleavage. Detailed comparison with the structure of human MPO allows us to identify differences that may contribute to the known divergent enzymatic properties. The crystal structure revealed fully established ester links between the prosthetic group and the protein, the comparably weak imidazolate character of the proximal histidine, and the conserved structure of the catalytic amino acids and Ca2+-binding site. Prediction of the structure of unprocessed proeosinophil peroxidase allows further structural analysis of the three protease cleavage sites and the potential pro-convertase recognition site in the propeptide. Finally, EPO biosynthesis and its biochemical and biophysical properties are discussed with respect to the available data from the well-studied MPO.

Inflammation in Prostate Cancer: Exploring the Promising Role of Phenolic Compounds as an Innovative Therapeutic Approach

Prostate cancer (PCa) remains a significant global health concern, being a major cause of cancer morbidity and mortality worldwide. Furthermore, profound understanding of the disease is needed. Prostate inflammation caused by external or genetic factors is a central player in prostate carcinogenesis. However, the mechanisms underlying inflammation-driven PCa remain poorly understood. This review dissects the diagnosis methods for PCa and the pathophysiological mechanisms underlying the disease, clarifying the dynamic interplay between inflammation and leukocytes in promoting tumour development and spread. It provides updates on recent advances in elucidating and treating prostate carcinogenesis, and opens new insights for the use of bioactive compounds in PCa. Polyphenols, with their noteworthy antioxidant and anti-inflammatory properties, along with their synergistic potential when combined with conventional treatments, offer promising prospects for innovative therapeutic strategies. Evidence from the use of polyphenols and polyphenol-based nanoparticles in PCa revealed their positive effects in controlling tumour growth, proliferation, and metastasis. By consolidating the diverse features of PCa research, this review aims to contribute to increased understanding of the disease and stimulate further research into the role of polyphenols and polyphenol-based nanoparticles in its management.

Monensin induces secretory granule-mediated cell death in eosinophils

BACKGROUND

Eosinophils contribute to the pathology of several types of disorders, in particular of allergic nature, and strategies to limit their actions are therefore warranted.

OBJECTIVE

We sought to evaluate the possibility of targeting the acidic, lysosome-like eosinophil granules as a potential means of inducing eosinophil cell death.

METHODS

To this end, we used monensin, an ionophoric drug that has previously been shown to permeabilize the secretory granules of mast cells, thereby inducing cell death.

RESULTS

Our findings reveal that monensin induces cell death in human eosinophils, whereas neutrophils were less affected. Blockade of granule acidification reduced the effect of monensin on the eosinophils, demonstrating that granule acidity is an important factor in the mechanism of cell death. Furthermore, monensin caused an elevation of the granule pH, which was accompanied by a decrease of the cytosolic pH, hence indicating that monensin caused leakage of acidic contents from the granules into the cytosol. In agreement with a granule-targeting mechanism, transmission electron microscopy analysis revealed that monensin caused extensive morphological alterations of the eosinophil granules, as manifested by a marked loss of electron density. Eosinophil cell death in response to monensin was caspase-independent, but dependent on granzyme B, a pro-apoptotic serine protease known to be expressed by eosinophils.

CONCLUSIONS

We conclude that monensin causes cell death of human eosinophils through a granule-mediated mechanism dependent on granzyme B.

Psychosocial stress-induced intestinal permeability in healthy humans: What is the evidence?

An impaired intestinal barrier function can be detrimental to the host as it may allow the translocation of luminal antigens and toxins into the subepithelial tissue and bloodstream. In turn, this may cause local and systemic immune responses and lead to the development of pathologies. In vitro and animal studies strongly suggest that psychosocial stress is one of the factors that can increase intestinal permeability via mast-cell dependent mechanisms. Remarkably, studies have not been able to yield unequivocal evidence that such relation between stress and intestinal permeability also exists in (healthy) humans. In the current Review, we discuss the mechanisms that are involved in stress-induced intestinal permeability changes and postulate factors that influence these alterations and that may explain the translational difficulties from in vitro and animal to human studies. As human research differs highly from animal research in the extent to which stress can be applied and intestinal permeability can be measured, it remains difficult to draw conclusions about the presence of a relation between stress and intestinal permeability in (healthy) humans. Future studies should bear in mind these difficulties, and more research into in vivo methods to assess intestinal permeability are warranted.

CCR3 gene knockout inhibits proliferation, differentiation, and migration of eosinophils in allergic rhinitis model mice

Allergic rhinitis (AR) is characterized by various bothersome clinical symptoms of the nasal mucosa that impaired the quality of daily life. Different chemokine receptors play a crucial role in the recruitment of inflammatory cells in AR. However, the effect of CC chemokine receptor (CCR) 3 on the function of eosinophils (EOS) is still unclear. We investigated the effect of CCR3 on EOS in a murine model of OVA-mediated allergic rhinitis using CCR3-deficient (CCR3-/-) mice. In vitro, bone marrow of CCR3-/- and wild-type (WT) mice were used to investigate the induction and development of EOS. In vivo, Allergic rhinitis was initiated in CCR3-/- and wild-type (WT) mice by passive transfer OVA, followed by detecting the eosinophil infiltration of the nasal mucosa and bone marrow. Then CD34+ progenitor cells in bone marrow and blood were evaluated by IHC analysis. Furthermore, the degranulation proteins of EOS in nasal mucosa, marrow, blood and NALF were determined by IHC, real-time PCR analysis and Western blot. We found that CCR3 gene can regulate the growth and development of primary cultured eosinophils. Knockout CCR3 gene can inhibit the proliferation and degranulation of EOS. The infiltration of eosinophils in the nasal mucosa following OVA-challenged, was significantly higher in WT mice compared with those stimulated with phosphate-buffered saline (PBS) for WT, but that was not seen in similarly treated CCR3-/- mice. Besides, the number of CD34+ progenitor cells in bone marrow and blood were also suppressed in CCR3-/- mice. The degranulation proteins of EOS expressed in nasal mucosa, marrow, blood and NALF were decreased in CCR3-/- AR mice compared with WT-AR mice. And the clinical symptoms were significantly alleviated. The expression of granulation proteins in NALF were not detected in both untreated CCR3-/- mice and WT mice. These results demonstrate a contribution of CCR3 to both the growth, migration, and degranulation of EOS during allergic rhinitis.

Efficacy of mometasone/indacaterol/glycopyrronium in patients with inadequately controlled asthma with respect to baseline eosinophil count: Post hoc analysis of IRIDIUM study

BACKGROUND

Baseline characteristics could potentially guide asthma treatments. We evaluated whether baseline eosinophil levels affect the efficacy of mometasone/indacaterol/glycopyrronium (MF/IND/GLY) in patients with inadequately controlled asthma.

METHOD

In this post hoc analysis of IRIDIUM study, efficacy of high-dose MF/IND/GLY (160/150/50 μg, once-daily [o.d.]) versus high-dose MF/IND (320/150 μg o.d.) and high-dose fluticasone/salmeterol (FLU/SAL [500/50 μg, twice-daily [b.i.d.]); and efficacy of pooled MF/IND/GLY (160/150/50 μg and 80/150/50 μg) versus pooled MF/IND (320/150 μg and 160/150 μg) was evaluated in patient subgroups with baseline blood eosinophil count of <300 cells/μL or ≥300 cells/μL.

RESULTS

Overall, 3065 patients were included. At Week 26, high-dose MF/IND/GLY showed improved trough FEV1 versus high-dose MF/IND (Δ78mL [<300 cells/μL]; Δ54mL [≥300 cells/μL]) and FLU/SAL (Δ112mL [<300 cells/μL]; Δ98mL [≥300 cells/μL]). Similarly, pooled MF/IND/GLY also showed improved trough FEV1 versus pooled MF/IND (Δ75mL [<300 cells/μL]; Δ68mL [≥300 cells/μL]). Over 52 weeks, high-dose MF/IND/GLY reduced the annualized rate of moderate or severe asthma exacerbations by 23% and 10%, severe exacerbations by 31% and 15%, and all exacerbation by 33% and 10% versus high-dose MF/IND for subgroups with <300 cells/μL and ≥300 cells/μL, respectively; and by 33% and 41%, 45% and 42%, 42% and 39% versus FLU/SAL, respectively. Similarly, pooled MF/IND/GLY reduced exacerbations by 22% and 8%, 21% and 7%, 27% and 8%, versus pooled MF/IND, for the respective subgroups.

CONCLUSION

MF/IND/GLY showed improvement in lung function and reduction in asthma exacerbations over MF/IND and FLU/SAL independent of baseline eosinophil levels, indicating that eosinophil levels did not affect the efficacy of MF/IND/GLY in patients with inadequately controlled asthma.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02571777 (IRIDIUM).

Eosinophils in the tumor microenvironment: implications for cancer immunotherapy

Despite being an integral part of the immune response in the tumor microenvironment (TME), few studies have mechanistically elucidated eosinophil functions in cancer outcomes. Eosinophils are a minor population of granulocytes that are mostly explored in asthma and allergic disorders. Their influence on primary and metastatic tumors, however, has recently come to light. Eosinophils' diverse armamentarium of mediators and receptors allows them to participate in innate and adaptive immunity, such as type 1 and type 2 immunity, and shape TME and tumor outcomes. Based on TME cells and cytokines, activated eosinophils drive other immune cells to ultimately promote or suppress tumor growth. Discovering exactly what conditions determine the pro-tumorigenic or anti-tumorigenic role of eosinophils allows us to take advantage of these signals and devise novel strategies to target cancer cells. Here, we first revisit eosinophil biology and differentiation as recognizing eosinophil mediators is crucial to their function in homeostatic and pathological conditions as well as tumor outcome. The bulk of our paper discusses eosinophil interactions with tumor cells, immune cells-including T cells, plasma cells, natural killer (NK) cells-and gut microbiota. Eosinophil mediators, such as IL-5, IL-33, granulocyte-macrophage colony-stimulating factor (GM-CSF), thymic stromal lymphopoietin (TSLP), and CCL11 also determine eosinophil behavior toward tumor cells. We then examine the implications of these findings for cancer immunotherapy approaches, including immune checkpoint blockade (ICB) therapy using immune checkpoint inhibitors (ICIs) and chimeric antigen receptor (CAR) T cell therapy. Eosinophils synergize with CAR T cells and ICB therapy to augment immunotherapies.

Cell-targeted vaccines: implications for adaptive immunity

Recent advancements in immunology and chemistry have facilitated advancements in targeted vaccine technology. Targeting specific cell types, tissue locations, or receptors can allow for modulation of the adaptive immune response to vaccines. This review provides an overview of cellular targets of vaccines, suggests methods of targeting and downstream effects on immune responses, and summarizes general trends in the literature. Understanding the relationships between vaccine targets and subsequent adaptive immune responses is critical for effective vaccine design. This knowledge could facilitate design of more effective, disease-specialized vaccines.

Dupilumab effectively and rapidly treats bullous pemphigoid by inhibiting the activities of multiple cell types

Background

Bullous pemphigoid (BP) is an autoimmune skin-blistering disease. Systemic corticosteroids remain the first line treatment for moderate-to-severe BP with the potential for severe adverse events. Dupilumab has emerged as an alternative option for BP patients.

Objective

We evaluated the efficiency and safety of dupilumab on BP treatment and explored a mode of drug action in depth.

Methods and results

A multicenter retrospective cohort included 20 BP patients who received dupilumab with or without systemic corticosteroid in dupilumab group, and 20 matched BP patients who received corticosteroid alone in conventional group. Serum samples were collected from 20 patients (10 from dupilumab group and 10 from conventional group) at baseline and week 4. Compared to systemic corticosteroid alone, dupilumab with or without systemic corticosteroid was similarly efficacious in clinical remission at week4 (complete remission plus partial remission: 100%) and week24 (complete remission plus partial remission:100%), but allowing significant decreases in the cumulative doses of corticosteroids with reducing the incidence of adverse events. However, dupilumab did not decrease BP180 antibody despite an obvious clinical improvement. Comparative plasma proteomic analysis performed before and after treatment in 3 BP patients from dupilumab group revealed that drug use was associated with 30 differentially expressed proteins, including 26 down-regulated and 4 up-regulated proteins. The former consisted of immune related proteins involved in T/B cell interactions (inducible T-cell co-stimulator ligand, ICOSL) and in the activation of eosinophils (PRG2), mast cells (S100A12), and complement (CR2). TARC and ICOSL levels correlated with BP severity in patients who received either dupilumab or conventional treatment.

Conclusion

Dupilumab has similar efficacy in treating BP as conventional drugs, by inhibiting the activities of many types of immune cells and complement, and regulating the interactions between T and B cells.

Eosinophil Subtypes in Adults with Asthma and Adults with Chronic Obstructive Pulmonary Disease

Rationale: There is a differential response to eosinophilic modulation between patients with asthma and those with chronic obstructive pulmonary disease (COPD). There is also evidence of different subtypes of eosinophils in murine models. However, no study has compared eosinophil subtypes in individuals with COPD and in those with asthma. Objectives: Study the differences in eosinophils subtypes based in the surface protein expression in COPD patients and asthmatic patients. Methods: We studied 10 stable subjects in each of four groups: subjects with COPD, subjects with asthma, smokers without COPD, and healthy volunteers. Subjects with COPD and those with asthma were matched by age, sex, and FEV1% predicted. The following variables were determined: anthropometrics, smoking, exacerbation history, medication use, lung function, and comorbidities. Using flow cytometry and confocal microscopy from blood samples, we determined differences in eosinophil surface proteins and classified them as 1) resident eosinophils (Siglec-8+CD62L+IL-3Rlo) or 2) inflammatory eosinophils (iEos; Siglec-8+CD62LloIL-3Rhi). IL-5 receptor was also determined. Findings were validated in 59 patients with COPD and in 17 patients with asthma. Measurements and Main Results: Patients with asthma had a higher proportion of iEos (25 ± 15%) compared with those with COPD (0.5 ± 1%), smokers without COPD (0.14 ± 0.24%), and healthy volunteers (0.67 ± 1.72%). In patients with asthma, the proportion of iEos was independent of total eosinophil number. iEos had more IL-5 receptors than resident eosinophils (777.02 ± 124.55 vs. 598.35 ± 318.69; P < 0.01). In patients with COPD, there was no relation between iEos number and inhaled corticosteroid use, disease severity, or exacerbations rate. The findings in patients with COPD and those with asthma were confirmed in validation cohorts. Conclusions: There are differences in the subtypes of circulating eosinophils between patients with asthma and those with COPD. This could have clinical implications in the interpretation of eosinophil significance and the approach to therapy in these patients.

Platelets and mast cells promote pathogenic eosinophil recruitment during invasive fungal infection via the 5-HIAA-GPR35 ligand-receptor system

Cryptococcus neoformans is the leading cause of fungal meningitis and is characterized by pathogenic eosinophil accumulation in the context of type-2 inflammation. The chemoattractant receptor GPR35 is expressed by granulocytes and promotes their migration to the inflammatory mediator 5-hydroxyindoleacetic acid (5-HIAA), a serotonin metabolite. Given the inflammatory nature of cryptococcal infection, we examined the role of GPR35 in the circuitry underlying cell recruitment to the lung. GPR35 deficiency dampened eosinophil recruitment and fungal growth, whereas overexpression promoted eosinophil homing to airways and fungal replication. Activated platelets and mast cells were the sources of GPR35 ligand activity and pharmacological inhibition of serotonin conversion to 5-HIAA, or genetic deficiency in 5-HIAA production by platelets and mast cells resulted in more efficient clearance of Cryptococcus. Thus, the 5-HIAA-GPR35 axis is an eosinophil chemoattractant receptor system that modulates the clearance of a lethal fungal pathogen, with implications for the use of serotonin metabolism inhibitors in the treatment of fungal infections.

Eosinophils as potential biomarkers in respiratory viral infections

Eosinophils are bone marrow-derived granulocytes that, under homeostatic conditions, account for as much as 1-3% of peripheral blood leukocytes. During inflammation, eosinophils can rapidly expand and infiltrate inflamed tissues, guided by cytokines and alarmins (such as IL-33), adhesion molecules and chemokines. Eosinophils play a prominent role in allergic asthma and parasitic infections. Nonetheless, they participate in the immune response against respiratory viruses such as respiratory syncytial virus and influenza. Notably, respiratory viruses are associated with asthma exacerbation. Eosinophils release several molecules endowed with antiviral activity, including cationic proteins, RNases and reactive oxygen and nitrogen species. On the other hand, eosinophils release several cytokines involved in homeostasis maintenance and Th2-related inflammation. In the context of SARS-CoV-2 infection, emerging evidence indicates that eosinophils can represent possible blood-based biomarkers for diagnosis, prognosis, and severity prediction of disease. In particular, eosinopenia seems to be an indicator of severity among patients with COVID-19, whereas an increased eosinophil count is associated with a better prognosis, including a lower incidence of complications and mortality. In the present review, we provide an overview of the role and plasticity of eosinophils focusing on various respiratory viral infections and in the context of viral and allergic disease comorbidities. We will discuss the potential utility of eosinophils as prognostic/predictive immune biomarkers in emerging respiratory viral diseases, particularly COVID-19. Finally, we will revisit some of the relevant methods and tools that have contributed to the advances in the dissection of various eosinophil subsets in different pathological settings for future biomarker definition.

The Role of Eosinophil-Derived Neurotoxin and Vascular Endothelial Growth Factor in the Pathogenesis of Eosinophilic Asthma

Asthma is a chronic complex pulmonary disease characterized by airway inflammation, remodeling, and hyperresponsiveness. Vascular endothelial growth factor (VEGF) and eosinophil-derived neurotoxin (EDN) are two significant mediators involved in the pathophysiology of asthma. In asthma, VEGF and EDN levels are elevated and correlate with disease severity and airway hyperresponsiveness. Diversity in VEGF polymorphisms results in the variability of responses to glucocorticosteroids and leukotriene antagonist treatment. Targeting VEGF and eosinophils is a promising therapeutic approach for asthma. We identified lichochalcone A, bevacizumab, azithromycin (AZT), vitamin D, diosmetin, epigallocatechin gallate, IGFBP-3, Neovastat (AE-941), endostatin, PEDF, and melatonin as putative add-on drugs in asthma with anti-VEGF properties. Further studies and clinical trials are needed to evaluate the efficacy of those drugs. AZT reduces the exacerbation rate and may be considered in adults with persistent symptomatic asthma. However, the long-term effects of AZT on community microbial resistance require further investigation. Vitamin D supplementation may enhance corticosteroid responsiveness. Herein, anti-eosinophil drugs are reviewed. Among them are, e.g., anti-IL-5 (mepolizumab, reslizumab, and benralizumab), anti-IL-13 (lebrikizumab and tralokinumab), anti-IL-4 and anti-IL-13 (dupilumab), and anti-IgE (omalizumab) drugs. EDN over peripheral blood eosinophil count is recommended to monitor the asthma control status and to assess the efficacy of anti-IL-5 therapy in asthma.

Eosinophilic Lung Diseases

The eosinophilic lung diseases may manifest as chronic eosinophilic pneumonia, acute eosinophilic pneumonia, or as the Löffler syndrome (generally of parasitic etiology). The diagnosis of eosinophilic pneumonia is made when both characteristic clinical-imaging features and alveolar eosinophilia are present. Peripheral blood eosinophils are generally markedly elevated; however, eosinophilia may be absent at presentation. Lung biopsy is not indicated except in atypical cases after multidisciplinary discussion. The inquiry to possible causes (medications, toxic drugs, exposures, and infections especially parasitic) must be meticulous. Idiopathic acute eosinophilic pneumonia may be misdiagnosed as infectious pneumonia. Extrathoracic manifestations raise the suspicion of a systemic disease especially eosinophilic granulomatosis with polyangiitis. Airflow obstruction is frequent in allergic bronchopulmonary aspergillosis, idiopathic chronic eosinophilic pneumonia, eosinophilic granulomatosis with polyangiitis, and hypereosinophilic obliterative bronchiolitis. Corticosteroids are the cornerstone of therapy, but relapses are common. Therapies targeting interleukin 5/interleukin-5 are increasingly used in eosinophilic lung diseases.

Macrophage Migration Inhibitory Factor in Psoroptes ovis: Molecular Characterization and Potential Role in Eosinophil Accumulation of Skin in Rabbit and Its Implication in the Host-Parasite Interaction

Psoroptes ovis, a common surface-living mite of domestic and wild animals worldwide, results in huge economic losses and serious welfare issues in the animal industry. P. ovis infestation rapidly causes massive eosinophil infiltration in skin lesions, and increasing research revealed that eosinophils might play an important role in the pathogenesis of P. ovis infestation. Intradermal injection of P. ovis antigen invoked massive eosinophil infiltration, suggesting that this mite should contain some relative molecules involved in eosinophil accumulation in the skin. However, these active molecules have not yet been identified. Herein, we identified macrophage migration inhibitor factor (MIF) in P. ovis (PsoMIF) using bioinformatics and molecular biology methods. Sequence analyses revealed that PsoMIF appeared with high similarity to the topology of monomer and trimer formation with host MIF (RMSD = 0.28 angstroms and 2.826 angstroms, respectively) but with differences in tautomerase and thiol-protein oxidoreductase active sites. Reverse transcription PCR analysis (qRT-PCR) results showed that PsoMIF was expressed throughout all the developmental stages of P. ovis, particularly with the highest expression in female mites. Immunolocalization revealed that MIF protein located in the ovary and oviduct of female mites and also localized throughout the stratum spinosum, stratum granulosum, and even basal layers of the epidermis in skin lesions caused by P. ovis. rPsoMIF significantly upregulated eosinophil-related gene expression both in vitro (PBMC: CCL5, CCL11; HaCaT: IL-3, IL-4, IL-5, CCL5, CCL11) and in vivo (rabbit: IL-5, CCL5, CCL11, P-selectin, ICAM-1). Moreover, rPsoMIF could induce cutaneous eosinophil accumulation in a rabbit model and increased the vascular permeability in a mouse model. Our findings indicated that PsoMIF served as one of the key molecules contributing to skin eosinophil accumulation in P. ovis infection of rabbits.

Clinical Potential of Eosinophil-Derived Neurotoxin in Asthma Management

The assessment and management of patients with asthma is challenging because of the complexity of the underlying inflammatory mechanisms and heterogeneity of their clinical presentation. Optimizing disease management requires therapy individualization that should rely on reliable biomarkers to unravel the phenotypes and endotypes of asthma. The secretory activity and turnover of eosinophils, as assessed by measuring eosinophil-derived proteins, may provide an accurate and complementary tool that mirrors the eosinophil activation status. Emerging evidence suggests that eosinophil-derived neurotoxin has considerable potential as a precision medicine biomarker. In this review, we explore the suitability of eosinophil-derived neurotoxin as a biomarker in asthma management, with particular emphasis on its clinical significance in the management of both pediatric and adult populations.

Biology of amphibian granulocytes - From evolutionary pressures to functional consequences

Granulocyte-lineage cells are important innate immune effectors across all vertebrates. Named for conspicuous secretory granules, granulocytes have historically been studied for their antimicrobial roles. Although versions of these cells are found in all vertebrate species examined to date, disparate environmental and physiological pressures acting on distinct vertebrate classes have shaped many of the facets dictating granulocyte biology. Immune pressures further determine granulopoietic constraints, ultimately governing granulocyte functions. For amphibians that inhabit pathogen-rich aquatic environments for some or all their lives, their unique granulocyte biologies satisfy many of their antimicrobial needs. Amphibians also occupy an intermediate position in the evolution of vertebrate immune systems, using combinations of primitive (e.g., subcapsular liver) and more recently evolved (e.g., bone marrow) tissue sites for hematopoiesis and specifically, granulopoiesis. The last decade of research has revealed vertebrate granulocytes in general, and amphibian granulocytes in particular, are more complex than originally assumed. With dynamic leukocyte phenotypes, granulocyte-lineage cells are being acknowledged for their multifaceted roles beyond immunity in other physiological processes. Here we provide an overview of granulopoiesis in amphibians, highlight key differences in these processes compared to higher vertebrates, and identify open questions.

Immune responses in mildly versus critically ill COVID-19 patients

The current coronavirus pandemic (COVID-19), caused by SARS-CoV-2, has had devastating effects on the global health and economic system. The cellular and molecular mediators of both the innate and adaptive immune systems are critical in controlling SARS-CoV-2 infections. However, dysregulated inflammatory responses and imbalanced adaptive immunity may contribute to tissue destruction and pathogenesis of the disease. Important mechanisms in severe forms of COVID-19 include overproduction of inflammatory cytokines, impairment of type I IFN response, overactivation of neutrophils and macrophages, decreased frequencies of DC cells, NK cells and ILCs, complement activation, lymphopenia, Th1 and Treg hypoactivation, Th2 and Th17 hyperactivation, as well as decreased clonal diversity and dysregulated B lymphocyte function. Given the relationship between disease severity and an imbalanced immune system, scientists have been led to manipulate the immune system as a therapeutic approach. For example, anti-cytokine, cell, and IVIG therapies have received attention in the treatment of severe COVID-19. In this review, the role of immunity in the development and progression of COVID-19 is discussed, focusing on molecular and cellular aspects of the immune system in mild vs. severe forms of the disease. Moreover, some immune- based therapeutic approaches to COVID-19 are being investigated. Understanding key processes involved in the disease progression is critical in developing therapeutic agents and optimizing related strategies.

Eosinophilia attention, diagnosis, treatment, and awareness in physicians: a cross-sectional survey

Background

Patients with incidental eosinophilia is becoming increasingly common in clinical practice. But it remains challenging to diagnose and treat owing to its complex etiology. The awareness of physicians and the strategies of diagnosis and treatment toward eosinophilia are still unclear.

Objective

We aimed to evaluate attention, diagnosis, treatment, and awareness of eosinophilia among physicians, as well as factors influencing clinical practice, and to find ways to improve the efficacy of this disease.

Design

This is a cross-sectional survey.

Methods

A cross-sectional study was conducted from 1 to 4 June 2021 in a tertiary hospital. Self-administered and validated electronic questionnaire was used to investigate the attention toward eosinophilia, the strategies of diagnosis and treatment, and the awareness in physicians.

Results

A total of 607 valid questionnaires were collected, with a response rate of 84.5%. Among the responders, 65.4% of physicians claimed to be familiar with patients with eosinophilia but only 11.0% of them had read the relevant guidelines or expert consensus. Among 207 physicians who had ever diagnosed patients with eosinophilia, only 19.4% had performed detailed examinations. The accuracy of awareness questions was 1.6-53.5%, and only 26.5% of physicians had high levels of awareness. An increase in the awareness level of up to 2.82 folds was seen among physicians with factors such as job title, encountering patients with eosinophilia, linking patients' conditions to peripheral blood eosinophil count, and paying attention to guidelines.

Conclusion

This study highlighted the importance of raising awareness and knowledge of eosinophilia among physicians in China. More works on education about eosinophilia guideline are needed, which may help physicians make decision with more benefits to patients.

Neonicotinoid Insecticides and Their Metabolites Can Pass through the Human Placenta Unimpeded

Studies on neonicotinoid (NEO) exposure in pregnant women and fetuses are scarce, and transplacental transfer of these insecticides is unknown. In this study, parent NEOs (p-NEOs) and their metabolites (m-NEOs) were determined in 95 paired maternal (MS) and cord serum (CS) samples collected in southern China. Imidacloprid was the predominant p-NEO in both CS and MS samples, found at median concentrations of 1.84 and 0.79 ng/mL, respectively, whereas N-desmethyl-acetamiprid was the most abundant m-NEO in CS (median: 0.083 ng/mL) and MS (0.13 ng/mL). The median transplacental transfer efficiencies (TTEs) of p-NEOs and m-NEOs were high, ranging from 0.81 (thiamethoxam, THM) to 1.61 (olefin-imidacloprid, of-IMI), indicating efficient placental transfer of these insecticides. Moreover, transplacental transport of NEOs appears to be passive and structure-dependent: cyanoamidine NEOs such as acetamiprid and thiacloprid had higher TTE values than the nitroguanidine NEOs, namely, clothianidin and THM. Multilinear regression analysis revealed that the concentrations of several NEOs in MS were associated significantly with hematological parameters related to hepatotoxicity and renal toxicity. To our knowledge, this is the first analysis of the occurrence and distribution of NEOs in paired maternal-fetal serum samples.

Immunopathologic Role of Eosinophils in Eosinophilic Chronic Rhinosinusitis

Chronic rhinosinusitis (CRS) is a diverse chronic inflammatory disease of the sinonasal mucosa. CRS manifests itself in a variety of clinical and immunologic patterns. The histological hallmark of eosinophilic CRS (ECRS) is eosinophil infiltration. ECRS is associated with severe disease severity, increased comorbidity, and a higher recurrence rate, as well as thick mucus production. Eosinophils play an important role in these ECRS clinical characteristics. Eosinophils are multipotential effector cells that contribute to host defense against nonphagocytable pathogens, as well as allergic and nonallergic inflammatory diseases. Eosinophils interact with Staphylococcus aureus, Staphylococcal enterotoxin B, and fungi, all of which were found in the tissue of CRS patients. These interactions activate Th2 immune responses in the sinonasal mucosa and exacerbate local inflammation. Activated eosinophils were discovered not only in the tissue but also in the sinonasal cavity secretion. Eosinophil extracellular traps (EETs) are extracellular microbes trapping and killing structures found in the secretions of CRS patients with intact granule protein and filamentous chromatic structures. At the same time, EET has a negative effect by causing an epithelial barrier defect. Eosinophils also influence the local tissue microenvironment by exchanging signals with other immune cells and structural cells. As a result, eosinophils are multifaceted leukocytes that contribute to various physiologic and pathologic processes of the upper respiratory mucosal immune system. The goal of this review is to summarize recent research on the immunopathologic properties and immunologic role of eosinophils in CRS.

Eosinophilic esophagitis: Immune mechanisms and therapeutic targets

Eosinophilic esophagitis (EoE) is an emerging chronic inflammatory disease of the oesophagus and is clinically characterized by upper gastrointestinal (GI) symptoms including dysphagia and esophageal food impaction. Histopathologic manifestations, which include intraepithelial eosinophilic inflammation and alterations of the esophageal squamous epithelium, such as basal zone hyperplasia (BZH) and dilated intercellular spaces (DIS), are thought to contribute to esophageal dysfunction and disease symptoms. Corroborative clinical and discovery science-based studies have established that EoE is characterized by an underlying allergic inflammatory response, in part, related to the IL-13/CCL26/eosinophil axis driving dysregulation of several key epithelial barrier and proliferative regulatory genes including kallikrein (KLK) serine proteases, calpain 14 (CAPN14) and anoctamin 1 (ANO1). The contribution of these inflammatory and proliferative processes to the clinical and histological manifestations of disease are not fully elucidated. Herein, we discuss the immune molecules and cells that are thought to underlie the clinical and pathologic manifestations of EoE and the emerging therapeutics targeting these processes for the treatment of EoE.

Emerging therapies targeting eosinophil-mediated inflammation in chronic allergic conjunctivitis

Ocular allergy remains a significant burden to the population while the treatment for the severe, chronic forms of allergic conjunctivitis remains largely limited to non-specific immunosuppressants. Eosinophils are central to the pathophysiology and sustaining the immunologic response found in the chronic forms of ocular allergy such as vernal keratoconjunctivitis and atopic keratoconjunctivitis. Several mediators of eosinophil recruitment, chemotaxis, adhesion, activation, and survival have been identified that offer potential therapeutic targets for ocular allergy. Based on preclinical and clinical data available in both ocular and non-ocular allergy studies, these emerging therapies warrant further investigation in reducing the severity of disease in patients with chronic ocular allergy.

Recent advances of eosinophils and its correlated diseases

Eosinophils are differentiated by bone marrow multipotent progenitor cells and are further released into peripheral blood after maturation. Human eosinophils can exhibit unique multi-leaf nuclear morphology, which are filled with cytoplasmic granules that contain cytotoxicity and immune regulatory proteins. In recent years, many studies focused on the origin, differentiation and development process of eosinophils. It has been discovered that the eosinophils have the regulatory functions of innate and adaptive immunity, and can also function in several diseases, including asthma, chronic obstructive pulmonary diseases, acute respiratory distress syndrome, malignant tumors and so on. Hence, the role and effects of eosinophils in various diseases are emphasized. In this review, we comprehensively summarized the development and differentiation process of eosinophils, the research progress of their related cytokines, diseases and current clinical treatment options, and discussed the potential drug target, aiming to provide a theoretical and practical basis for the clinical prevention and treatment of eosinophil-related diseases, especially respiratory diseases. To conclude, the guiding significance of future disease treatment is proposed based on the recent updated understandings into the cell functions of eosinophils.

OX40 Expression in Eosinophils Aggravates OVA-Induced Eosinophilic Gastroenteritis

Background & Aims

Eosinophils are the main inflammatory effector cells that damage gastrointestinal tissue in eosinophilic gastrointestinal diseases (EGIDs). Activation of the OX40 pathway aggravates allergic diseases, such as asthma, but it is not clear whether OX40 is expressed in eosinophils to regulate inflammation in EGIDs. In this study, we assessed the expression and effect of OX40 on eosinophils in WT and Ox40^-/- eosinophilic gastroenteritis (EGE) mice.

Methods

Eosinophil infiltration, ovalbumin (OVA)-specific Ig production, OX40 expression and inflammatory factor levels in the intestine and bone marrow (BM) were investigated to evaluate inflammation.

Results

We confirmed that OVA-challenged mice produced high levels of Ox40, Mbp, Ccl11, Il5, Il4, Il13, and Il6 mRNA and a low level of Ifng mRNA in the intestine. Increased eosinophils were observed in intestinal and lymph tissues, accompanied by significantly upregulated OX40 and Type 2 cytokine production in eosinophils of EGE mice. Ox40 deficiency ameliorated OVA-induced inflammation, eosinophil infiltration, and cytokine production in the intestine. Consistently, Ox40^{-/ -} eosinophils exhibited decreased proliferation and proinflammatory function. The stimulation of the agonistic anti-OX40 antibody, OX86, promoted the effect of OX40 on eosinophils. The present study also showed that Ox40 deficiency dampened the Traf2/6-related NF-κB signaling pathway in eosinophils.

Conclusions

OX40 may play a critical role in the progress of OVA-induced EGE by promoting the maturation and function of eosinophils via the Traf2/6-related NF-κB signaling pathway.

Assessing the role of eosinophil-mediated immune response markers in detecting hookworm infection: A case-control study in Kintampo, Ghana

Background and Aim

Human hookworm disease caused by Ancylostoma duodenale and Necator americanus is a serious public health problem. Hookworm infection activates eosinophil‐mediated tissue inflammatory responses, involving the production of the eosinophil‐specific chemokine (eotaxin), recruitment of eosinophils, secretion of the cationic protein, and production of antiparasite immunoglobulin E (IgE). We investigated eosinophil‐mediated immune response as markers (CCL11, eosinophil cationic protein [ECP], and IgE) for detecting hookworm infection.

Methods

This case‐control study was carried out in hookworm endemic areas within the Kintampo North Municipality.Forty hookworm‐positive subjects and 36 apparently healthy individuals were recruited as cases and controls, respectively. Stool samples were collected for hookworm detection by the Kato–Katz technique and speciation by polymerase chain reaction. Approximately, 5 ml of intravenous blood was used to obtain plasma for the immunological assays.

Results

Of eosinophil‐mediated immune response markers studied, ECP and CCL11 were significantly higher among hookworm patients compared to controls. Increasing CCL11 (β = −0.81, p = 0.015) was associated with a significant decrease hookworm intensity. However, increasing eosinophil count (β = 0.62, p = 0.027) was associated with significant increase in hookworm intensity. In receiver operator characteristics analysis, ECP could significantly detect hookworm infection with a very high area under the curve (AUC) (AUC = 0.97, p < 0.0001). At a cutoff of 39.05, ECP was the best eosinophil‐mediated immune response marker for detecting hookworm infection with a sensitivity of 97.2%, specificity of 87.8%, a positive predictive value of 89.7%, and a negative predictive value of 96.6%.

Conclusion

ECP best predicts eosinophil‐mediated immune response for detecting hookworm infection, while CCL11 and eosinophil count better predict the intensity of hookworm. Moreover, the ECP level is a good indicator of hookworm infection and intensity and may require additional investigations to augment current hookworm diagnostic techniques.

Role of IL-25 on Eosinophils in the Initiation of Th2 Responses in Allergic Asthma

Background

Eosinophils act as a secondary antigen-presenting cell (APC) to stimulate Th cell responses against antigens. IL-25 plays a significant role in eosinophil activation in allergic asthma. The role of IL-25 on the classic APC functions of dendritic cells has been elucidated. However, whether IL-25 facilitates eosinophils for antigen presentation is unknown.

Objective

To elucidate the role of IL-25 on eosinophils antigen presenting function during allergic asthma and its related mechanism.

Methods

Eosinophils from allergic asthma subjects were cultured with IL-25 and HDM to identify the co-stimulator molecules expression. Co-cultures of patient eosinophils and autologous naïve CD4⁺ T cells in the same culture system were to explore whether eosinophils had the capacity to promote Th cell differentiation in response to IL-25 engagement. In asthma mouse model, IL-25^-/- mice were exposed to HDM to investigate the effect of IL-25 on eosinophils during the sensitization phase. The impact of IL-25 on the capacity for eosinophils taking up antigens was evaluated. Mouse bone marrow derived eosinophils (BmEOS) were co-cultured with naïve CD4⁺T cells sorted from spleens under HDM and IL-25 stimulation to identify T cell differentiation.

Results

IL-25 upregulated HLA-DR, PD-L1, and OX-40L expression on eosinophils from allergic asthma patients. IL-25 and HDM co-sensitized eosinophils promoted Th2 differentiation. In mouse model, IL-25^-/- mice experienced restrained allergic pulmonary inflammation and reduced eosinophils recruitment and antigen uptake capacity during the early sensitization phase. In vitro, IL-25 promoted antigen uptake by eosinophils. In BmEOS and naïve CD4⁺T cells co-culture, IL-25 accreted the proportion of CD4⁺Th2 cells, which was absent in CD4⁺T cells culture alone.

Conclusion

Our data identify a novel role of IL-25 in enhancing eosinophils antigen uptake and co-stimulator molecules expression to induce Th2 priming in the context of allergic inflammation.

Eosinophils and Lung Cancer: From Bench to Bedside

Eosinophils are rare, multifunctional granulocytes. Their growth, survival, and tissue migration mainly depend on interleukin (IL)-5 in physiological conditions and on IL-5 and IL-33 in inflammatory conditions. Preclinical evidence supports an immunological role for eosinophils as innate immune cells and as agents of the adaptive immune response. In addition to these data, several reports show a link between the outcomes of patients treated with immune checkpoint inhibitors (ICI) for advanced cancers and blood eosinophilia. In this review, we present, in the context of non-small cell lung cancer (NSCLC), the biological properties of eosinophils and their roles in homeostatic and pathological conditions, with a focus on their pro- and anti-tumorigenic effects. We examine the possible explanations for blood eosinophilia during NSCLC treatment with ICI. In particular, we discuss the value of eosinophils as a potential prognostic and predictive biomarker, highlighting the need for stronger clinical data. Finally, we conclude with perspectives on clinical and translational research topics on this subject.

Venous thromboembolism in chronic gastrointestinal disorders

INTRODUCTION

Chronic gastrointestinal disorders (including autoimmune gastritis, celiac disease, inflammatory bowel disease, and diverticular disease) are highly prevalent disorders, that may be associated with unpredictable, life-threatening complications, such as thromboembolic events. Venous thromboembolism (VTE) is one of the major causes of morbidity and mortality worldwide. Several conditions, including cancer, major trauma, surgery, prolonged immobilization, are well-established risk factors for VTE. Over the past decade, chronic inflammation has also been identified as an independent risk factor for VTE due to the prothrombotic effects of inflammatory cytokines and oxidative stress on the coagulation cascade. Other several mechanisms were shown to be associated with a higher incidence of VTE in patients with gastrointestinal disorders.

AREAS COVERED

We critically discuss the latest insights into the mechanisms responsible for thromboembolic manifestations in chronic gastrointestinal disorders, also focusing on the recognition of risk factors and treatment.

EXPERT OPINION

The occurrence of thrombotic complications is underestimated in patients with chronic gastrointestinal disorders. Identifying potential risk factors and concomitant predisposing conditions and to prevent VTE and guide treatment require a multidisciplinary approach, and this is critically important for clinicians, in order to provide the best care for such patients.

The regulatory role of eosinophils in viral, bacterial, and fungal infections

Eosinophils are innate immune cells typically associated with allergic and parasitic diseases. However, in recent years, eosinophils have also been ascribed a role in keeping homeostasis and in fighting several infectious diseases. Indeed, these cells circulate as mature cells in the blood and can be quickly recruited to the infected tissue. Moreover, eosinophils have all the necessary cellular equipment such as pattern recognition receptors (PRRs), pro-inflammatory cytokines, anti-bacterial proteins, and DNA traps to fight pathogens and promote an efficient immune response. This review summarizes some of the updated information on the role of eosinophils' direct and indirect mediated interactions with pathogens.

Dietary L-Carnitine Affects Leukocyte Count and Function in Dairy Cows Around Parturition

In early lactation, an energy deficit leading to a negative energy balance (NEB) is associated with increased susceptibility to disease and has been shown to be an important factor during transition in dairy cows. L-carnitine as a key factor in the mitochondrial transport of fatty acids and subsequently for β-oxidation and energy release is known to modulate mitochondrial biogenesis and thus influence metabolism and immune system. In the current study, we characterized hematological changes around parturition and investigated the potential effects of dietary L-carnitine supplementation on immune cell functions. For this approach, dairy cows were assigned either to a control (CON, n = 30) or an L-carnitine group [CAR, n = 29, 25 g rumen-protected L-carnitine per cow and day (d)]. Blood samples were taken from d 42 ante partum (ap) until d 110 post-partum (pp), with special focus and frequent sampling from 0.5 to72 h post-calving to clarify the impact of L-carnitine supplementation on leukocyte count, formation of reactive oxygen species (ROS) in polymorphonuclear cells (PMN) and peripheral mononuclear cells (PBMC) and their phagocytosis activity. Blood cortisol concentration and the capacity of PBMC proliferation was also investigated. All populations of leukocytes were changed during the peripartal period, especially granulocytes showed a characteristic increase up to 4 h pp. L-carnitine supplementation resulted in increased levels of eosinophils which was particularly pronounced one day before to 4 h pp, indicating a possible enhanced support for tissue repair and recovery. Non-supplemented cows showed a higher phagocytic activity in PBMC as well as a higher phagocytic capacity of PMN during the most demanding period around parturition, which may relate to a decrease in plasma levels of non-esterified fatty acids reported previously. L-carnitine, on the other hand, led to an increased efficiency to form ROS in stimulated PMN. Finally, a short period around calving proved to be a sensitive period in which L-carnitine administration was effective.