Eosinophils: singularly destructive effector cells or purveyors of immunoregulation?

Staphylococcus aureus in Inflammation and Pain: Update on Pathologic Mechanisms

Staphylococcus aureus (S. aureus) is a Gram-positive bacterium of significant clinical importance, known for its versatility and ability to cause a wide array of infections, such as osteoarticular, pulmonary, cardiovascular, device-related, and hospital-acquired infections. This review describes the most recent evidence of the pathogenic potential of S. aureus, which is commonly part of the human microbiota but can lead to severe infections. The prevalence of pathogenic S. aureus in hospital and community settings contributes to substantial morbidity and mortality, particularly in individuals with compromised immune systems. The immunopathogenesis of S. aureus infections involves intricate interactions with the host immune and non-immune cells, characterized by various virulence factors that facilitate adherence, invasion, and evasion of the host's defenses. This review highlights the complexity of S. aureus infections, ranging from mild to life-threatening conditions, and underscores the growing public health concern posed by multidrug-resistant strains, including methicillin-resistant S. aureus (MRSA). This article aims to provide an updated perspective on S. aureus-related infections, highlighting the main diseases linked to this pathogen, how the different cell types, virulence factors, and signaling molecules are involved in the immunopathogenesis, and the future perspectives to overcome the current challenges to treat the affected individuals.

Repeated saline injections reduce the pulmonary allergic inflammatory response in rats by inducing short-term stress

Purpose

Asthma is characterized by pulmonary cell infiltration and hyper-responsiveness of the airways. Short-term stress reduces airway inflammation. Thus, in the present study, we examined the effects of short-term stress induced by repeated treatment with saline injections on the pulmonary allergic inflammatory response in rats.

Methods

Adult male rats were divided into three groups: Naïve group (non-sensitized, challenged, or treated rats), Control group (rats sensitized with ovalbumin (OVA) to induce lung inflammation), and Saline group (rats treated for five days with saline before OVA sensitization). Inhalation challenges were performed one week after the booster with aerosolized OVA. On day 18, the effect of saline injections on total and differential leukocytes in bronchoalveolar lavage (BAL), femoral marrow lavage (FML), and blood was evaluated. The percentage of mucus, serum corticosterone, collagen, cytokines in lung explants, and norepinephrine levels were also measured.

Results

OVA sensitization increased the circulating leukocytes and their migration to the lung, decreasing the bone marrow leukocytes. The repeated saline injections prevented this migration by decreasing the number of leukocytes in BAL and blood in the control group. Cytokine Interleukin-4 (IL-4) was higher in the control group than in the naive and saline groups; cytokines Interleukin-6 (IL-6), Interleukin-10 (IL-10), and tumor necrosis factor-alpha (TNFα) were higher in the control and saline groups than in the naïve group; Interferon gamma (IFNγ) was higher in the saline group than in the naive and control groups; norepinephrine increased in animals sensitized with OVA and was higher only in the saline group relative to the naïve group.

Conclusions

These results suggest that short-term stress could contribute to the anti-allergic airway inflammation effects of a given treatment.

Transfluthrin is Associated with High Susceptibility to Asthma in Children with Promoter Variants of Beta Chain of High-Affinity Receptor IgE and Tumour Necrosis Factors-α Genes

This study investigates the genetic variations in FcεR1β-109 C/T (rs512555) and TNF-α-308 G/A (rs1800629) genes and examines whether the mosquito repellent transfluthrin (TFT) modifies the risk for asthmatic children. A case-control study was conducted involving 130 asthmatic children and 123 age-sex matched controls. Differential leukocyte counts, IgE, and hs-CRP levels were estimated using a five-part haematology analyzer and Beckman Coulter (AU480), respectively. Genetic variations in FcεR1β-109 and TNF-α-308 were analysed using restriction fragment length polymorphism. Serum TFT levels were measured using gas chromatography-tandem mass spectrometry. Asthmatic children had significantly increased total leukocyte, neutrophil, lymphocyte, eosinophil, and basophil counts (p < 0.0001), while their monocyte counts were lower compared to controls (p < 0.0001). TFT levels were higher in asthmatic children (1.38 ± 0.91 vs. control 0.69 ± 0.41µg/L, p < 0.0001), which predominantly induced wheezing. Elevated TFT levels were associated with an increased risk of childhood asthma (OR: 3.08, p < 0.0001). Children with the FcεRIβ TT (OR: 2.39, p < 0.017) and TNF-α GG genotypes (OR: 7.17, p < 0.0001) were more susceptible to asthma. TFT synergistically enhanced the risk of asthma in both FcεRIβ-109 TT (OR: 5.3, p = 0.001) and TNF-α-308 GG (OR: 17.18, p < 0.0001) genotypes. TFT levels were correlated with IgE (r = 0.363; p = 0.006), hs-CRP (r = 0.324; p = 0.049) and eosinophil (r = 0.300; p = 0.038), respectively. IgE and eosinophils were correlated (r = 0.599, p = 0.001) in the FcεRIβ TT genotype-carrying asthmatic children. Similarly, neutrophils and hs-CRP were correlated (r = 0.768, p < 0.0001) in asthmatic children with TNF-α GG genotype. The risk of asthma is inherently higher in children with FcεRIβ TT and TNF-α GG variants. TFT exposure amplifies the risk of asthma in children among all the subgenotypes of both genes. TFT influences IgE and eosinophil in FcεRIβ TT genotype while it influences neutrophils and hs-CRP in TNF-α GG genotypes.

Eosinophil biology from the standpoint of metabolism: implications for metabolic disorders and asthma

Eosinophils, recognized for their immune and remodeling functions and participation in allergic inflammation, have recently garnered attention due to their impact on host metabolism, especially in the regulation of adipose tissue. Eosinophils are now known for their role in adipocyte beiging, adipokine secretion, and adipose tissue inflammation. This intricate interaction involves complex immune and metabolic processes, carrying significant implications for systemic metabolic health. Importantly, the interplay between eosinophils and adipocytes is bidirectional, revealing the dynamic nature of the immune-metabolic axis in adipose tissue. While the homeostatic regulatory role of eosinophils in adipose tissue is appreciated, this relationship in the context of obesity or allergic inflammation is much less understood. Mechanistic details of eosinophil-adipose interactions, especially the direct regulation of adipocytes by eosinophils, are also lacking. Another poorly understood aspect is the metabolism of the eosinophils themselves, encompassing metabolic shifts during eosinophil subset transitions in different tissue microenvironments, along with potential effects of host metabolism on the programming of eosinophil hematopoiesis and the resulting plasticity. This review consolidates recent research in this emerging and fascinating frontier of eosinophil investigation, identifying unexplored areas and presenting innovative perspectives on eosinophil biology in the context of metabolic disorders and associated health conditions, including asthma.

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.

Scabies: Immunopathogenesis and pathological changes

Scabies is an itchy skin disease caused by the burrowing mite Sarcoptes scabiei. During their lifespan, the female mites invade the stratum corneum and create tunnels, in which they reside, move, feed, deposit fecal pellets, and lay eggs. Recently, scabies was included in the World Health Organization roadmap for neglected tropical diseases 2021-2030. This review attempts to summarize our knowledge about the mite's biology and the disease pathogenesis, pathological changes, and complications. Generally, the host-parasite interaction in scabies is highly complex and involves different mechanisms, some of which are yet largely unknown. Elucidation of the nature of such interaction as well as the underlying mechanisms could allow a better understanding of the mite's biology and the development of novel diagnostic and therapeutic options for scabies control programs. Moreover, identification of the molecular basis of such interaction could unveil novel targets for acaricidal agents and vaccines.

Effects of Lidocaine-Derived Organic Compounds on Eosinophil Activation and Survival

Lidocaine, a local anesthetic, is known to possess anti-inflammatory properties. However, its clinical use is limited by inconveniences, such as its local synesthetic effects. This study evaluated lidocaine analogs designed and synthesized to overcome the disadvantages of lidocaine, having anti-inflammatory properties. Interleukin 5 (IL-5)-induced eosinophil activation and survival were evaluated using 36 lidocaine analogs with modified lidocaine structure on the aromatic or the acyl moiety or both. Eosinophil survival was evaluated using a CellTiter 96® aqueous cell proliferation assay kit. Superoxide production was determined using the superoxide dismutase-inhibitable reduction of cytochrome C method. Eosinophil cationic protein (ECP), IL-8, and transcription factor expression were determined using enzyme-linked immunosorbent assay. The platelet-activating factor (PAF)-induced migration assay was performed using a Transwell insert system. Compounds EI137 and EI341 inhibited IL-5-induced eosinophil survival and superoxide and ECP production in a concentration-dependent manner. These compounds also significantly reduced IL-8 production. Although compounds EI137 and EI341 significantly reduced phosphorylated ERK 1/2 expression, they did not influence other total and phosphorylated transcription factors. Moreover, 1000 µM of compound EI341 only inhibited PAF-induced migration of eosinophils. Lidocaine analogs EI137 and EI341 inhibited IL-5-mediated activation and survival of eosinophils. These compounds could be new therapeutic agents to treat eosinophilic inflammatory diseases.

The Predictive Values of White Blood Cell Indices (Lymphocyte and Eosinophilic Granulocyte) for Heart Failure in Acute Coronary Syndrome Patients Following Percutaneous Coronary Intervention: A Prospective Cohort Study

Background

White blood cell (WBC) indices are strongly associated with cardiovascular disease, but data on the prognostic values of these parameters in patients with acute coronary syndrome (ACS) following percutaneous coronary intervention (PCI) are sparse. The current study aimed to investigate the relationship between baseline WBC indices levels and the incidence of heart failure (HF) in ACS patients after PCI and explore the predictive values over a 2-year follow-up period.

Methods

A total of 416 consecutive ACS patients treated with PCI were enrolled and received a median of 27.7 months follow-up. Univariate and multivariate Cox regression analyses and the receiver operating characteristic (ROC) curves were performed.

Results

Baseline lymphocyte (LYMPH) count, eosinophil (EO) count and eosinophil percentage (EO %) were higher in patients who experienced HF over a 2-year follow-up. In multivariate Cox proportional hazards analysis, LYMPH count, EO count and EO % were independently associated with the occurrence of HF (hazard ratio [HR] = 12.876, P = 0.025; HR = 16.625, P = 0.004; HR = 1.196, P = 0.031, respectively). The area under the ROC curve of baseline EO count predicting the occurrence of HF in ACS patients following PCI was 0.625 (P = 0.037). For patients aged 60 years and above, who had PCI or history of coronary artery bypass grafting, the higher EO count, the higher the risk of HF.

Conclusion

Elevated baseline LYMPH count, EO count and EO % were independently associated with the incidence of HF in ACS patients following PCI, suggesting that WBC indices might be available, simple, and cost-efficient biomarkers with predictive value, especially for patients aged more than 60 years.

Benralizumab in the management of rare primary eosinophilic lung diseases

Background: Eosinophils have a double-edged role in the human body, being essential in important physiologic functions but whose presence is conspicuous in a variety of diseases characterized by a T2 inflammation phenotype. Eosinophils are exquisitely sensitive to corticosteroids, and the latter have, until recently, represented the cornerstone of treatment of eosinophilic diseases. However, most patients remain dependent on oral corticosteroids, with a notable adverse effect burden and experience a chronic relapsing disease that leads to high morbidity and mortality. Treatment prospects have changed with the advent of biologic drugs that target the eosinotropic cytokine interleukin (IL) 5 or its receptor. The success of the latter drugs in severe eosinophilic asthma has paved the way for their use in other, rarer, eosinophilic lung diseases. Recently, mepolizumab, a humanized monoclonal antibody that works against IL-5, was approved for the add-on treatment of relapsing-remitting or refractory eosinophilic granulomatosis with polyangiitis (EGPA) in patients ages ≥ 6 years. Benralizumab, a humanized antibody that binds to the α portion of the IL-5 receptor, is also being tested for its efficacy in EGPA in two clinical trials, after a growing number of case reports and case series supported its use as a steroid-sparing agent in the treatment of EGPA. Methods: In this review, we summarized the scientific literature evaluating the efficacy of benralizumab treatment in patients afflicted with rare primary eosinophilic lung diseases. Results: The literature we found, largely case reports, reported that the use of benralizumab in EGPA, chronic eosinophilic pneumonia (CEP) and allergic bronchopulmonary aspergillosis (ABPA) often led to a depletion of eosinophils, less exacerbations and a decreased systemic corticosteroid burden. No adverse effects were reported. Conclusion: Benralizumab has a prospective role in the treatment of rare eosinophilic lung diseases, which needs to be further elucidated in randomized controlled trials.

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.

The Predictive Value of Eosinophil Indices for Major Cardiovascular Events in Patients with Acute Decompensated HFrEF

Background and Objectives: Heart failure is a chronic disease with a high risk of mortality and morbidity. In these patients, inflammatory markers have been shown to be associated with cardiovascular adverse outcomes and disease progression. To investigate the relationships between eosinophil indices and major cardiovascular events (MACE) in patients with acute decompensated heart failure (ADHF) with reduced ejection fraction. Materials and Methods: A total of 395 consecutive patients admitted to the intensive care unit (ICU) with ADHF and reduced ejection fraction between January 2017 and December 2021 were enrolled in this retrospective study. MACE was defined as the composite of death and re-hospitalization for ADHF within 6 months of index hospitalization. All-cause mortality and MACE were assessed with respect to relationships with eosinophil indices, including neutrophil-to-eosinophil ratio (NER), leukocyte-to-eosinophil ratio (LER), eosinophil-to-lymphocyte ratio (ELR), and eosinophil-to-monocyte ratio (EMR). Results: NER and LER were significantly higher in subjects with MACE. Absolute eosinophil, lymphocyte and basophil count, hemoglobin, serum Na+, albumin, and CRP, and EMR and ELR were significantly lower in subjects with MACE compared to those without. NT-proBNP (OR: 1.682, 95% CI: 1.106−2.312, p = 0.001), Na+ (OR: 0.932, 95% CI: 0.897−0.969, p < 0.001), NER (OR: 2.740, 95 % CI: 1.797−4.177, p < 0.001), LER (OR: 2.705, 95% CI: 1.752−4.176, p < 0.001), EMR (OR:1.654, 95% CI 1.123−2.436, p = 0.011), ELR (OR: 2.112, 95% CI 1.424−3.134, p < 0.001), and eosinophil count (OR: 1.833, 95% CI 1.276−2.635) were independent predictors for development of MACE. Conclusions: Patients with ADHF and reduced ejection fraction who developed MACE within the first six months of index hospitalization had lower levels of absolute eosinophil and lymphocyte counts, and EMR and ELR values, whereas NER and LER were higher compared to those without MACE. The eosinophil indices were independently associated with mortality and MACE development. The eosinophil indices may be used to estimate MACE likelihood with acceptable sensitivity and specificity.

Schistosomiasis Mansoni-Recruited Eosinophils: An Overview in the Granuloma Context

Eosinophils are remarkably recruited during schistosomiasis mansoni, one of the most common parasitic diseases worldwide. These cells actively migrate and accumulate at sites of granulomatous inflammation termed granulomas, the main pathological feature of this disease. Eosinophils colonize granulomas as a robust cell population and establish complex interactions with other immune cells and with the granuloma microenvironment. Eosinophils are the most abundant cells in granulomas induced by Schistosoma mansoni infection, but their functions during this disease remain unclear and even controversial. Here, we explore the current information on eosinophils as components of Schistosoma mansoni granulomas in both humans and natural and experimental models and their potential significance as central cells triggered by this infection.

Solving the Conundrum of Eosinophils in Alloimmunity

Eosinophils are bone-marrow-derived granulocytes known for their ability to facilitate clearance of parasitic infections and their association with asthma and other inflammatory diseases. The purpose of this review is to discuss the currently available human observational and animal experimental data linking eosinophils to the immunologic response in solid organ transplantation. First, we present observational human studies that demonstrate a link between transplantation and eosinophils yet were unable to define the exact role of this cell population. Next, we describe published experimental models and demonstrate a defined mechanistic role of eosinophils in downregulating the alloimmune response to murine lung transplants. The overall summary of this data suggests that further studies are needed to define the role of eosinophils in multiple solid organ allografts and points to the possibility of manipulating this cell population to improve graft survival.

Potential role of embelin in the prevention of Freund's adjuvant induced inflammation and ROS

Inflammation is a complex biological response involving immune cells to an infection creating injury to the normal tissues. The anti-inflammatory efficacy of embelin, a benzoquinone from the plant Embelia ribes, was screened for antioxidant and anti-inflammatory activity in carrageenan and Freund's adjuvant-induced inflammation models. Embelin exhibited significant dose-dependent antioxidant potential. In carrageenan-induced inflammation, embelin (20 mg/kg) showed an inhibition of oedema by 71.01 ± 0.12% and 81.91 ± 0.67% in Freund's adjuvant-treated chronic inflammation model and resulted in a noticeable increase in adrenal size and restoration of the weight of spleen. Embelin also demonstrated cytoprotective effects on HEK-293 cells under induced oxidative stress. In silico analysis, embelin demonstrated binding energy of - 7.7 kcal/Mol and - 7.0 kcal/Mol with COX1 and COX2 with two hydrogen bonds. These results further prove that embelin could be a promising anti-inflammatory agent and supports the traditional use of Embelia ribes for rheumatism.

Peripheral blood eosinophilia as a marker of acute cellular rejection in lung transplant recipients

Previous studies in solid organ transplantation have shown a relationship between circulating eosinophil (EOS) counts and the presence of acute cellular rejection (ACR). However, the relationship between this potential biomarker and ACR in lung transplant (LTx) patients remains unclear.

OBJECTIVE

To assess the association between EOS and the presence of acute cellular rejection in lung transplant recipients.

MATERIALS AND METHODS

Retrospective study of 583 transbronchial biopsies (TBB) performed in 256 lung transplant patients between 2012 and 2018. We analyzed age, sex, underlying pathology, date of transplant, indications for TBB, presence and degree of ACR, and the simultaneous absolute and relative EOS.

RESULTS

ACR were observed in 170 of 583 TBB (29.2%). EOS in patients with ACR were higher than in patients without ACR (203.6 ± 248/mm³ vs 103.1 ± 153/mm³; p < 0.001). High levels of both absolute and relative EOS were associated with the presence of ACR regardless of the underlying disease (odds ratio [OR] 1.003; 95% confidence interval [CI], 1.002-1.004; OR 1.226; 95% CI, 1.120-1.342) and time after transplant (OR 1.003; 95% CI, 1.002-1.004 and OR 1.239; 95% CI, 1.132-1.356). Moreover, both absolute and relative EOS were strongly associated with moderate and severe grades of ACR (OR 3.55; 95% CI, 3.00-4.10 and OR 3.56; 95% CI, 3.00-4.12).

CONCLUSIONS

EOS are elevated in ACR, especially in moderate or severe ACR. Increased vigilance for ACR is therefore advisable in lung transplant recipients with elevated EOS.

Differential expression of Triggering Receptor Expressed on Myeloid cells 2 (Trem2) in tissue eosinophils

No longer regarded simply as end-stage cytotoxic effectors, eosinophils are now recognized as complex cells with unique phenotypes that develop in response stimuli in the local microenvironment. In our previous study, we documented eosinophil infiltration in damaged muscle characteristic of dystrophin-deficient (mdx) mice that model Duchenne muscular dystrophy. Specifically, we found that eosinophils did not promote the generation of muscle lesions, as these persisted in eosinophil-deficient mdx.PHIL mice. To obtain additional insight into these findings, we performed RNA sequencing of eosinophils isolated from muscle tissue of mdx, IL5tg, and mdx.IL5tg mice. We observed profound up-regulation of classical effector proteins (major basic protein-1, eosinophil peroxidase, and eosinophil-associated ribonucleases) in eosinophils isolated from lesion-free muscle from IL5tg mice. By contrast, we observed significant up-regulation of tissue remodeling genes, including proteases, extracellular matrix components, collagen, and skeletal muscle precursors, as well as the immunomodulatory receptor, Trem2, in eosinophils isolated from skeletal muscle tissue from the dystrophin-deficient mdx mice. Although the anti-inflammatory properties of Trem2 have been described in the monocyte/macrophage lineage, no previous studies have documented its expression in eosinophils. We found that Trem2 was critical for full growth and differentiation of bone marrow-derived eosinophil cultures and full expression of TLR4. Immunoreactive Trem2 was also detected on human peripheral blood eosinophils at levels that correlated with donor body mass index and total leukocyte count. Taken together, our findings provide important insight into the immunomodulatory and remodeling capacity of mouse eosinophils and the flexibility of their gene expression profiles in vivo.

Sequential Histopathological Changes and Cytokine Expressions in Dogs Naturally Infested with Sarcoptes scabiei Mites

BACKGROUND

The diagnosis and treatment of canine scabies remain quite challenging as a result of the meddling of the invertebrate mite Sarcoptes scabiei var canis with the immunologic activity of its host.

PURPOSE

This study aims to evaluate and better understand the immunologic, histomorphometric, histopathologic changes as well as their relationship in scabies infestation.

METHOD

Ten healthy dogs were housed with five sarcoptes-ridden dogs. Skin biopsies were then obtained afterwards for 7 weeks into buffered formalin. Sections of obtained biopsies were processed and incubated in IL-4, IL-13, IL-17A and IL-23A antibodies, while the other sections were stained for cellular alterations, quantifications and measurement of tunnel height and diameters. Pearson's product-moment correlation was used to establish the association between the cytokines and the measured tunnel heights and diameters, while Student's t test and one-way analysis of variance were used to test for weekly significant differences in cytokine expressions.

RESULTS

Histopathologic changes and early expression of all studied cytokines, eosinophils and mast cells were pronounced from the second week of infestation. Quite notable was the consistent amount of IL-13 and IL-23A all through the study duration. A dissimilar association was also observed between anti-inflammatory cytokines (IL-4 and IL-13) and pro-inflammatory cytokines (IL-17A and IL-23A). Also observed was the negative relationship between IL-13 and IL-23A as an increase in IL-13 was associated with a decrease in IL-23A. Tunnel height increase was also positively associated with pro-inflammation.

CONCLUSION

Immunodiagnosis can possibly be achieved with IL-13 and IL-23A expressions, while immunotherapy seems possible with IL-13 cytokine therapy.

Combination of eosinophil percentage and high-sensitivity C-reactive protein predicts in-hospital major adverse cardiac events in ST-elevation myocardial infarction patients undergoing primary percutaneous coronary intervention

Background

Eosinophil levels predict prognosis in ST‐segment elevation myocardial infarction (STEMI) patients. Both eosinophils and high‐sensitivity C‐reactive protein (hs‐CRP) play a major role in the acute inflammatory response of myocardial infarction. The purpose of this study was to evaluate eosinophil percentage (EOS%) and hs‐CRP as prognostic markers for in‐hospital adverse events in STEMI patients undergoing primary percutaneous coronary intervention.

Methods

We retrospectively analyzed the clinical data of 518 patients. Major adverse cardiac events (MACEs) were defined as cardiac rupture, cardiac arrest, malignant arrhythmia, and cardiac death. Based on the receiver operating characteristic (ROC) analysis, all patients were regrouped into 3 groups (None, One, and Two) according to cutoff EOS% value (≤0.3%) and hs‐CRP value (>11.8 mg/L). Both Cox regression analyses and the KM (Kaplan‐Meier) survival curve were used to examine the prognostic role of combined hs‐CRP and EOS% in cardiovascular events.

Results

Of the 518 STEMI patients, 50 of them developed MACEs. Patients who developed MACEs had a significantly lower EOS% and higher hs‐CRP than patients who remained MACE‐free. In the multivariable Cox regression analysis, the highest risk of in‐hospital MACEs was constantly observed in patients with a combined low EOS% and elevated hs‐CRP. Patients with reduced EOS% and high hs‐CRP had significantly higher incidence rates of cardiac rupture (P = .001), cardiac arrest (P = .001), and malignant arrhythmia (P < .001); furthermore, they had the worst cumulative survival compared with the other two groups.

Conclusion

Combined reduced EOS% and elevated hs‐CRP were valuable tools for identifying patients at risk of in‐hospital MACEs.

Comparison of IL-33 and IL-5 family mediated activation of human eosinophils

Eosinophils are the prominent inflammatory cell involved in allergic asthma, atopic dermatitis, eosinophilic esophagitis, and hypereosinophilic syndrome and are found in high numbers in local tissue and/or circulating blood of affected patients. There is recent interest in a family of alarmins, including TSLP, IL-25 and IL-33, that are epithelial-derived and released upon stimulation of epithelial cells. Several genome wide association studies have found SNPs in genes encoding IL-33 to be risk factors for asthma. In two studies examining the direct role of IL-33 in eosinophils, there were differences in eosinophil responses. We sought to further characterize activation of eosinophils with IL-33 compared to activation by other cytokines and chemokines. We assessed IL-33 stimulated adhesion, degranulation, chemotaxis and cell surface protein expression in comparison to IL-3, IL-5, and eotaxin-1 on human eosinophils. Our results demonstrate that IL-33 can produce as potent eosinophil activation as IL-3, IL-5 and eotaxin-1. Thus, when considering specific cytokine targeting strategies, IL-33 will be important to consider for modulating eosinophil function.

The alpha-melanocyte-stimulating hormone acts as a local immune homeostasis factor in experimental allergic asthma

BACKGROUND

Originally, the neuropeptide α-melanocyte-stimulating hormone (α-MSH) has been described as a mediator of skin pigmentation. However, recent studies have shown that α-MSH is able to modulate inflammation in various tissues including the lung. So far, it is still not clear whether α-MSH also plays a role in allergic bronchial asthma.

OBJECTIVE

This study aimed at investigating the role and regulatory mechanisms of α-MSH in asthma pathogenesis.

METHODS

α-MSH levels were measured in bronchoalveolar lavage (BAL) fluid of asthmatic and non-asthmatic individuals as well as of healthy mice and mice with experimental asthma. Wild-type mice were sensitized to ovalbumin (OVA) and exposed to an OVA aerosol in order to induce experimental allergic asthma. α-MSH was administrated intratracheally, the α-MSH antibody intraperitoneally prior each OVA challenge. Airway inflammation, cytokine production, mucus production, airway hyperresponsiveness and receptor expression were assessed.

RESULTS

α-MSH levels in BAL of asthmatic individuals and mice were significantly higher compared to healthy controls. In a mouse model of experimental asthma, α-MSH neutralization increased airway inflammation and mucus production, whereas local administration of α-MSH significantly reduced inflammation of the airways. The beneficial effects were further associated with decreased levels of eosinophilic chemoattractant factors that are released by MC5R-positive T helper 2 and airway epithelial cells.

CONCLUSION AND CLINICAL RELEVANCE

α-MSH acts as a regulatory factor to maintain local immune homeostasis in allergic bronchial asthma.

Emerging Roles for Immune Cells and MicroRNAs in Modulating the Response to Cardiac Injury

Stimulating cardiomyocyte regeneration after an acute injury remains the central goal in cardiovascular regenerative biology. While adult mammals respond to cardiac damage with deposition of rigid scar tissue, adult zebrafish and salamander unleash a regenerative program that culminates in new cardiomyocyte formation, resolution of scar tissue, and recovery of heart function. Recent studies have shown that immune cells are key to regulating pro-inflammatory and pro-regenerative signals that shift the injury microenvironment toward regeneration. Defining the genetic regulators that control the dynamic interplay between immune cells and injured cardiac tissue is crucial to decoding the endogenous mechanism of heart regeneration. In this review, we discuss our current understanding of the extent that macrophage and regulatory T cells influence cardiomyocyte proliferation and how microRNAs (miRNAs) regulate their activity in the injured heart.

Eosinophil-Associated Innate IL-17 Response Promotes Aspergillus fumigatus Lung Pathology

Aspergillus fumigatus is a common widespread microorganism with environmental, biological and clinical relevance. After inhalation, swollen conidia can germinate, colonize and invade pulmonary tissues. Eosinophils have been described as key cells in A. fumigatus lung infection. However, their specific role in protecting or damaging lung tissue as well as their relatioship among different A. fumigatus strains is poorly understood. Previously, it has been reported that eosinophils are able to produce IL-17 and mediate an innate response that protected mice from infection using Af293 and CEA10 strains. Here, we have developed a set of new experiments with the CEA17-derived A1163 strain of A. fumigatus. Using ΔdblGATA1 mice, we demonstrate that eosinophils produce IL-17 and are involved in control of neutrophil, macrophage and lymphocyte recruitment. We found that eosinophils also induce high levels of cytokines and chemokines, generating an intense inflammatory process. Eosinophils are responsible for increased pulmonary dysfunction and elevated lethality rates in mice. Curiously, fungal burden was not affected. To address the role of IL-17 signaling, pharmacological inhibition of this mediator in the airways with anti-IL-17 antibody was able to reduce inflammation in the airways and protect infected mice. In conclusion, our results demonstrate that eosinophils control IL-17-mediated response and contribute to lung pathology after A. fumigatus infection. Therefore, eosinophils may represent a potential target for controlling exacerbated inflammation and prevent tissue damage during this fungal infection.

Characterization and implications of the dynamics of eosinophils in blood and in the infarcted myocardium after coronary reperfusion

Objective

We characterized the dynamics of eosinophils in blood and in the infarcted myocardium in patients and in a swine model of reperfused myocardial infarction (MI). The association of eosinophil dynamics with various outcomes was assessed.

Methods

Serial eosinophil count and pre-discharge cardiac magnetic resonance were carried out in a prospective series of 620 patients with a first ST-elevation MI. In a swine model of reperfused MI, the dynamics of circulating eosinophils and their presence in the infarcted myocardium were determined. In autopsies from chronic MI patients, eosinophils were quantified.

Results

Patient eosinophil count sharply decreased 12h post-reperfusion compared to arrival. A lower minimum eosinophil count was associated with more extensive edema, microvascular obstruction, and infarct size as measured by cardiac magnetic resonance, and also with a higher rate of cardiac events (death, re-infarction, or heart failure) during follow-up. In the experimental model, eosinophil count boosted during ischemia and dropped back immediately post-reperfusion. Myocardial samples revealed progressive eosinophil migration into the infarcted myocardium, especially areas with microvascular obstruction. Markers of eosinophil maturation and survival (interleukin-5), degranulation (eosinophil cationic protein) and migration (eotoxin-1) were detected in the blood of patients, and in porcine myocardium. Eosinophil infiltration was detected in autopsies from chronic MI patients.

Conclusion

Eosinopenia post-MI was associated with an impaired cardiac structure and adverse events. The decay in circulating eosinophils soon after reperfusion mirrors their migration into the infarcted myocardium, as reflected by their presence in heart samples from swine and patients. Further studies are needed to understanding this unexplored pathway and its therapeutic implications.

Association of eosinophil-to-monocyte ratio with 1-month and long-term all-cause mortality in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention

Background

To determine the relationship between eosinophil-to-monocyte ratio (EMR) on admission and one-month and long-term all-cause mortality in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (P-PCI).

Methods

A total of 426 consecutive STEMI patients treated with P-PCI were enrolled and categorized in terms of tertiles of EMR on admission between September 2015 and October 2017. Final follow-up for long-term outcomes was January 2017.

Results

As EMR decreased, all-cause mortality at 1 month (mean, 29.5±3.5 days) and at mean 14.1±7.8 months follow-up increased (P=0.012, P=0.003, respectively). Kaplan-Meier survival curve analysis showed EMR was associated with 1-month and long-term all-cause mortality (P=0.048, P=0.015, respectively). In multivariate Cox proportional hazards analysis, EMR was independently associated with one-month and long-term mortality (hazard ratio =0.097; 95% CI, 0.010-0.899; P=0.04; hazard ration =0.176; 95% CI, 0.045-0.694; P=0.013). The area under the curve of EMR for the prediction of 1-month and long-term total mortality in receiver operating characteristic analysis was 0.789 (95% CI, 0.658-0.921; P=0.003) and 0.752 (95% CI, 0.619-0.884; P=0.001), respectively.

Conclusions

EMR on admission was independently correlated with 1-month and long-term all-cause mortality in STEMI patients undergoing P-PCI, suggesting EMR as a potential simple, useful, and inexpensive index for risk stratification of STEMI patients.

Oxidative stress in chronic lung disease: From mitochondrial dysfunction to dysregulated redox signaling

The lung is a delicate organ with a large surface area that is continuously exposed to the external environment, and is therefore highly vulnerable to exogenous sources of oxidative stress. In addition, each of its approximately 40 cell types can also generate reactive oxygen species (ROS), as byproducts of cellular metabolism and in a more regulated manner by NOX enzymes with functions in host defense, immune regulation, and cell proliferation or differentiation. To effectively regulate the biological actions of exogenous and endogenous ROS, various enzymatic and non-enzymatic antioxidant defense systems are present in all lung cell types to provide adequate protection against their injurious effects and to allow for appropriate ROS-mediated biological signaling. Acute and chronic lung diseases are commonly thought to be associated with increased oxidative stress, evidenced by altered cellular or extracellular redox status, increased irreversible oxidative modifications in proteins or DNA, mitochondrial dysfunction, and altered expression or activity of NOX enzymes and antioxidant enzyme systems. However, supplementation strategies with generic antioxidants have been minimally successful in prevention or treatment of lung disease, most likely due to their inability to distinguish between harmful and beneficial actions of ROS. Recent studies have attempted to identify specific redox-based mechanisms that may mediate chronic lung disease, such as allergic asthma or pulmonary fibrosis, which provide opportunities for selective redox-based therapeutic strategies that may be useful in treatment of these diseases.

Revisiting the NIH Taskforce on the Research needs of Eosinophil-Associated Diseases (RE-TREAD)

Eosinophil-associated diseases (EADs) are rare, heterogeneous disorders characterized by the presence of eosinophils in tissues and/or peripheral blood resulting in immunopathology. The heterogeneity of tissue involvement, lack of sufficient animal models, technical challenges in working with eosinophils, and lack of standardized histopathologic approaches have hampered progress in basic research. Additionally, clinical trials and drug development for rare EADs are limited by the lack of primary and surrogate endpoints, biomarkers, and validated patient-reported outcomes. Researchers with expertise in eosinophil biology and eosinophil-related diseases reviewed the state of current eosinophil research, resources, progress, and unmet needs in the field since the 2012 meeting of the NIH Taskforce on the Research of Eosinophil-Associated Diseases (TREAD). RE-TREAD focused on gaps in basic science, translational, and clinical research on eosinophils and eosinophil-related pathogenesis. Improved recapitulation of human eosinophil biology and pathogenesis in murine models was felt to be of importance. Characterization of eosinophil phenotypes, the role of eosinophil subsets in tissues, identification of biomarkers of eosinophil activation and tissue load, and a better understanding of the role of eosinophils in human disease were prioritized. Finally, an unmet need for tools for use in clinical trials was emphasized. Histopathologic scoring, patient- and clinician-reported outcomes, and appropriate coding were deemed of paramount importance for research collaborations, drug development, and approval by regulatory agencies. Further exploration of the eosinophil genome, epigenome, and proteome was also encouraged. Although progress has been made since 2012, unmet needs in eosinophil research remain a priority.

Pathogenic characterization of porcine reproductive and respiratory syndrome virus of Indian origin in experimentally infected piglets

Porcine reproductive and respiratory syndrome (PRRS) is an economically important transboundary viral disease of pigs confronting the swine industry worldwide. This study was aimed to assess the pathogenic potential of PRRS virus belonging to genotype 2 that emerged in India in 2013. Nine 6-week-old piglets were inoculated intranasally with 2 × 10^5.75  TCID₅₀ /ml of PRRSV (Ind-297221/2013). Three piglets were kept as uninfected controls. Blood and nasal swabs were collected daily up to 7 days post-infection (dpi) and on alternate days subsequently. Piglets were necropsied for tissue sample collection either on death or after euthanasia on 7, 14 or 21 dpi (one uninfected control and three PRRSV-infected piglets per interval). The virus caused high fever, typical blue ear, weight loss, respiratory distress, diarrhoea and leucopenia between 2 and 8 dpi. Two infected piglets died (on 3 and 17 dpi) during the course of study. The presence of virus in serum and nasal secretion was observed up to 19 and 17 dpi, respectively, with the maximum load between 4 and 7 dpi. Seroconversion started 6 dpi and the mean PRRSV antibody titre reached up to 640 by 21 dpi. Virus load was highest in tonsils at all the intervals, whereas in spleen and lymph nodes load was higher in later intervals. Major microscopic lesions in PRRSV-infected piglets included moderate to severe interstitial pneumonia, lymphoid depletion in tonsils and lymph nodes (cystic), thymic atrophy, reactive hyperplasia followed by lymphoid depletion in spleen. PRRSV antigen was consistently demonstrated by immunoperoxidase test in the lungs, spleen, tonsils and lymph nodes. Antigen distribution was more widespread on 7 and 14 dpi than on 21 dpi. The findings establish that the Indian PRRSV is highly pathogenic to piglets.

Nest predation risk modifies nestlings' immune function depending on the level of threat

Predation risk is thought to modify the physiology of prey mainly through the stress response. However, little is known about its potential effects on the immunity of animals, particularly in young individuals, despite the importance of overcoming wounding and pathogen aggression following a predator attack. We investigated the effect of four progressive levels of nest predation risk on several components of the immune system in common blackbird (Turdus merula) nestlings by presenting them with four different calls during 1 h: non-predator calls, predator calls, parental alarm calls and conspecific distress calls to induce a null, moderate, high and extreme level of risk, respectively. Nest predation risk induced an increase in ovotransferrin, immunoglobulin and the number of lymphocytes and eosinophils. Thus, the perception of a potential predator per se could stimulate the mobilization of a nestling's immune function and enable the organism to rapidly respond to the immune stimuli imposed by a predator attack. Interestingly, only high and extreme levels of risk caused immunological changes, suggesting that different immunological parameters are modulated according to the perceived level of threat. We also found a mediator role of parasites (i.e. Leucocytozoon) and the current health status of the individual, as only nestlings not parasitized or in good body condition were able to modify their immune system. This study highlights a previously unknown link between predation risk and immunity, emphasizing the complex relationship among different selective pressures (predation, parasitism) in developing organisms and accentuating the importance of studying predation from a physiological point of view.

Hypoxia, Metabolism and Immune Cell Function

Hypoxia is a hallmark of inflamed, infected or damaged tissue, and the adaptation to inadequate tissue oxygenation is regulated by hypoxia-inducible factors (HIFs). HIFs are key mediators of the cellular response to hypoxia, but they are also associated with pathological stress such as inflammation, bacteriological infection or cancer. In addition, HIFs are central regulators of many innate and adaptive immunological functions, including migration, antigen presentation, production of cytokines and antimicrobial peptides, phagocytosis as well as cellular metabolic reprogramming. A characteristic feature of immune cells is their ability to infiltrate and operate in tissues with low level of nutrients and oxygen. The objective of this article is to discuss the role of HIFs in the function of innate and adaptive immune cells in hypoxia, with a focus on how hypoxia modulates immunometabolism.

Targeting the Interleukin-5 Pathway for Treatment of Eosinophilic Conditions Other than Asthma

Improved understanding of the contribution of eosinophils to various chronic inflammatory conditions, most notably allergic asthma, has encouraged development of monoclonal antibodies specifically targeting mediators and surface receptors involved in eosinophil expansion and activation. The pivotal role of interleukin-5 (IL-5) in eosinophil biology, its high specificity for this leukocyte subset, and its involvement in the majority of eosinophilic conditions make it a very enticing target for treatment of eosinophil-mediated disorders. Two types of antibodies have been developed to target eosinophils: antibodies against IL-5 (mepolizumab and reslizumab), and an antibody against the IL-5-receptor-alpha-chain (IL-5Rα) (benralizumab). Both types of antibodies prevent IL-5 from engaging its receptor and in addition, anti-IL-5Rα antibodies induce target-cell lysis. They have been shown to reduce circulating eosinophil counts rapidly in humans with various disorders. Herein, a brief overview of the role of IL-5 in eosinophil biology will be presented, followed by a description of the development and characteristics of antibodies targeting IL-5 or its receptor. Results of clinical trials evaluating the efficacy and safety of these new antibodies in diseases (other than eosinophilic asthma) with prominent tissue eosinophilia are reviewed, followed by safety considerations and potential future applications.

Mast cells, basophils and eosinophils: From allergy to cancer

Basophils, eosinophils and mast cells were first recognized by Paul Ehrlich in the late 19th century. These cells have common, but non-redundant roles, in the pathogenesis of allergic diseases and in the protection against parasites. Nevertheless, in virtue of their shared-adeptness to produce a huge variety of immunological mediators and express membrane-bound receptors, they are able to interact with immune and non-immune components of the tissue microenvironment, contributing to the regulation of tissue homeostasis and immune response while participating to further deregulation of tissues transforming into neoplasia.

Short-Term Hyperprolactinemia Reduces the Expression of Purinergic P2X7 Receptors during Allergic Inflammatory Response of the Lungs

PURPOSE

We have previously shown that domperidone-induced short-term hyperprolactinemia reduces the lung's allergic inflammatory response in an ovalbumin antigenic challenge model. Since purinergic receptor P2X7R activity leads to proinflammatory cytokine release and is possibly related to the pathogenesis of allergic respiratory conditions, the present study was designed to investigate a possible involvement of purinergic and prolactin receptors in this phenomenon.

METHODS

To induce hyperprolactinemia, domperidone was injected intraperitoneally in rats at a dose of 5.1 mg × kg-1 per day for 5 days. P2X7 expression was evaluated by lung immunohistochemistry while prolactin receptor expression in bronchoalveolar lavage leukocytes was analyzed through flow cytometry.

RESULTS

Previous reports demonstrated that rats subjected to short-term hyperprolactinemia exhibited a decrease in leukocyte counts in bronchoalveolar lavage, especially granulocytes. Here, it is revealed that hyperprolactinemia promotes an increased expression of prolactin receptors in granulocytes. Also, increased expression of purinergic P2X7R observed in allergic animals was significantly reduced by hyperprolactinemia.

CONCLUSIONS

Both purinergic and prolactin receptor expression changes occur during the anti-asthmatic effect of hyperprolactinemia.

Eosinophils promote inducible NOS-mediated lung allograft acceptance

Lungs allografts have worse long-term survival compared with other organ transplants. This is most likely due to their unique immunoregulation that may not respond to traditional immunosuppression. For example, local NO generation by inducible NOS (iNOS) is critical for lung allograft acceptance but associates with rejection of other solid organs. The source of NO in accepting lung allografts remains unknown. Here, we report that, unlike the case for other pulmonary processes in which myeloid cells control NO generation, recipient-derived eosinophils play a critical and nonredundant role in iNOS-mediated lung allograft acceptance. Depletion of eosinophils reduces NO levels to that of recipients with global deletion of iNOS and leads to a costimulatory blockade-resistant form of rejection. Furthermore, NO production by eosinophils depends on Th1 polarization by inflammatory mediators, such as IFN-γ and TNF-α. Neutralization of such mediators abrogates eosinophil suppressive capacity. Our data point to what we believe to be a unique and previously unrecognized role of eosinophil polarization in mediating allograft tolerance and put into perspective the use of high-dose eosinophil-ablating corticosteroids after lung transplantation.

The Role of Nicotinamide Adenine Dinucleotide Phosphate Oxidases in Lung Architecture Remodeling

Chronic lung disorders, such as pulmonary artery hypertension (PAH), chronic obstructive pulmonary disease (COPD), asthma and neonatal bronchopulmonary dysplasia (BPD), are characterized by airway and/or vascular remodeling. Despite differences in the pathology, reactive oxygen species (ROS) have been highlighted as a critical contributor to the initiation and development of airway and vascular remodeling. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (Nox) appear to play a pivotal role in lung signaling, leading to marked changes in pulmonary airway and vascular cell phenotypes, including proliferation, hypertrophy and apoptosis. In this review, we summarized the current literature regarding the role of Nox in the airway and vascular remodeling.

Eosinophils as putative therapeutic targets in bullous pemphigoid

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering skin disease and is characterized by the presence of autoantibodies directed against the hemidesmosomal proteins BP180 and BP230 that can be detected in the skin and serum of BP patients. Histologically, the dermal infiltration of eosinophils is obvious. The objective of this review was to present evidence that eosinophils play a key role in the pathogenesis of BP. Eosinophils, together with cytokines and chemokines regulating their production, recruitment and activation, are abundantly present in lesional skin, in blisters and in peripheral blood of patients with BP. Recently, using a cryosection model, eosinophils were demonstrated to induce dermal-epidermal separation in the presence of BP antibodies. Thus, eosinophils and their products, as well as mediators regulating their function, present promising targets for the treatment of BP.

Host immune responses to the itch mite, Sarcoptes scabiei, in humans

Scabies is a parasitic disease due to infestation of skin by the burrowing mite Sarcoptes scabiei. Scabies is a major public health problem and endemic in resource poor communities worldwide affecting over 100 million people. Associated bacterial infections cause substantial morbidity, and in severe cases can lead to renal and cardiac diseases. Mite infestation of the skin causes localised cutaneous inflammation, pruritus, skin lesions, and allergic and inflammatory responses are mounted by the host against the mite and its products. Our current understanding of the immune and inflammatory responses associated with the clinical manifestations in scabies is far outweighed by the significant global impact of the disease. This review aims to provide a better understanding of human immune responses to S. scabiei in ordinary and crusted scabies phenotypes.

Lung Pathologies in a Chronic Inflammation Mouse Model Are Independent of Eosinophil Degranulation

RATIONALE

The release of eosinophil granule proteins in the lungs of patients with asthma has been dogmatically linked with lung remodeling and airway hyperresponsiveness. However, the demonstrated inability of established mouse models to display the eosinophil degranulation occurring in human subjects has prevented a definitive in vivo test of this hypothesis.

OBJECTIVES

To demonstrate in vivo causative links between induced pulmonary histopathologies/lung dysfunction and eosinophil degranulation.

METHODS

A transgenic mouse model of chronic T-helper cell type 2-driven inflammation overexpressing IL-5 from T cells and human eotaxin 2 in the lung (I5/hE2) was used to test the hypothesis that chronic histopathologies and the development of airway hyperresponsiveness occur as a consequence of extensive eosinophil degranulation in the lung parenchyma.

MEASUREMENT AND MAIN RESULTS

Studies targeting specific inflammatory pathways in I5/hE2 mice surprisingly showed that eosinophil-dependent immunoregulative events and not the release of individual secondary granule proteins are the central contributors to T-helper cell type 2-induced pulmonary remodeling and lung dysfunction. Specifically, our studies highlighted a significant role for eosinophil-dependent IL-13 expression. In contrast, extensive degranulation leading to the release of major basic protein-1 or eosinophil peroxidase was not causatively linked to many of the induced pulmonary histopathologies. However, these studies did define a previously unappreciated link between the release of eosinophil peroxidase (but not major basic protein-1) and observed levels of induced airway mucin.

CONCLUSIONS

These data suggest that improvements observed in patients with asthma responding to therapeutic strategies ablating eosinophils may occur as a consequence of targeting immunoregulatory mechanisms and not by simply eliminating the destructive activities of these purportedly end-stage effector cells.

Inflammatory biomarkers for asthma endotyping and consequent personalized therapy

We argue that asthma be considered a syndrome caused by multiple inflammatory pathogenic processes. Bronchial hyperresponsiveness, reversible airflow limitation, and chronic airway inflammation characterize asthma pathophysiology. Personalized Medicine, i.e. a tailored management approach, is appropriate for asthma management and is based on the identification of discrete phenotypes and endotypes. Biomarkers can help define phenotypes and endotypes. Several biomarkers have been described in asthma, but most of them are not commonly available or still need external validation. Areas covered: This review presents useful pragmatic biomarkers available in daily clinical practice for assessing airway inflammation in asthmatic patients. Expert commentary: Eosinophil counts and serum allergen-specific IgE assessments are the most reliable biomarkers. Lung function, mainly concerning FEF25-75, and nasal cytology may be envisaged as ancillary biomarkers in asthma management. In conclusion, biomarkers have a clinical relevance in asthma in identifying asthma endotypes to direct personalized therapy.

Biomarkers in asthmatic patients: Has their time come to direct treatment?

Asthma is a heterogeneous disease with multiple phenotypes that have variable risk factors and responses to therapeutics. Mild-to-moderate asthma often responds to traditional medications, whereas severe disease can be refractory to inhaled corticosteroids, long-acting β-agonists, and leukotriene receptor antagonists. There is robust research into the variable phenotypes of asthma. Biomarkers help define the specific pathophysiology of different asthma phenotypes and identify potential therapeutic targets. The following review will discuss the current use of biomarkers for the diagnosis of asthma, triaging the severity of a patient's disease, and the potential efficacy of treatments. This information can be used to define certain patient populations that are more likely to respond to inhaled corticosteroids or biologics. As knowledge of patient phenotypes and endotypes and biological agents to target specific classes of asthma emerge, the ability to provide personalized care to asthmatic patients will follow.

White Blood Cell Subtypes Are Associated with a Greater Long-Term Risk of Death after Acute Myocardial Infarction

We evaluated the association between white blood cell counts and long-term mortality rates in 2,129 patients (mean age, 65.3 ± 13.5 yr; 69% men) who had survived acute myocardial infarction. We obtained white blood cell counts and differential counts of white blood cell subtypes within the first 72 hours of hospital admission. The primary outcome was all-cause death at 1, 5, and 10 years after acute myocardial infarction. In regard to death in the long term, we found significant negative linear associations (lymphocytes), positive linear associations (neutrophils and the neutrophil-to-lymphocyte ratio), and nonlinear U-shaped associations (basophils, eosinophils, monocytes, and total white blood cell count). After multivariate adjustment for the Soroka Acute Myocardial Infarction risk score, lymphocytes (strongest association), neutrophil-to-lymphocyte ratio, and eosinophils were independently associated with death for up to 10 years after hospital discharge. The independent associations weakened over time. We conclude that lymphocyte count, neutrophil-to-lymphocyte ratio, and eosinophil count are independently and incrementally associated with death in the long term after acute myocardial infarction.

Pathogenicity of three genetically diverse strains of PRRSV Type 1 in specific pathogen free pigs

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The pathogenicity of two PRRSV-1 strains BOR59, ILI6 and 18794 was compared specific pathogen free pigs.

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The most pronounced clinical signs, the highest viremia and the earliest acute phase proteins response were in pigs infected with BOR59 strain.

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BOR59 strain can be considered a highly virulent strain, while the virulence of strain ILI6 was intermediate between BOR59 and 18794.

Studies from Eastern European countries proved that porcine reproductive and respiratory syndrome virus Type 1 (PRRSV-1) harbours high genetic diversity and that genetically divergent subtypes 2–4 circulate in this area.

In the present study, we compared the pathogenicity of two different PRRSV-1 subtype 2 strains and a strain representing PRRSV-1 subtype 1. Four groups of 8-week-old specific pathogen free pigs were either infected with subtype 2 strain ILI6, subtype 2 strain or BOR59, subtype 1 strain 18794, or mock inoculated.

The most pronounced clinical signs were observed in pigs infected with BOR59. Pigs from both subtype 2 strain infected groups exhibited significantly elevated mean body temperatures on DPI 2 compared to the other two groups, the difference remaining significant up to DPI 13 for the BOR59 group, only. The pigs in the latter group also displayed significantly highest levels of early viremia together with the most rapid APP response.

Overall, the results indicated that BOR59 strain can be considered a highly pathogenic strain, similarly to subtype 3 strains Lena and SU1-bel, while the virulence of the other subtype 2 strain ILI6 was intermediate between BOR59 and subtype 1 strain.

Innate immunity as the orchestrator of allergic airway inflammation and resolution in asthma

The respiratory system is constantly in direct contact with the environment and, has therefore, developed strong innate and adaptive immune responses to combat pathogens. Unlike adaptive immunity which is mounted later in the course of the immune response and is naive at the outset, innate immunity provides the first line of defense against microbial agents, while also promoting resolution of inflammation. In the airways, innate immune effector cells mainly consist of eosinophils, neutrophils, mast cells, basophils, macrophages/monocytes, dendritic cells and innate lymphoid cells, which attack pathogens directly or indirectly through the release of inflammatory cytokines and antimicrobial peptides, and coordinate T and B cell-mediated adaptive immunity. Airway epithelial cells are also critically involved in shaping both the innate and adaptive arms of the immune response. Chronic allergic airway inflammation and linked asthmatic disease is often considered a result of aberrant activation of type 2 T helper cells (Th2) towards innocuous environmental allergens; however, innate immune cells are increasingly recognized as key players responsible for the initiation and the perpetuation of allergic responses. Moreover, innate cells participate in immune response regulation through the release of anti-inflammatory mediators, and guide tissue repair and the maintenance of airway homeostasis. The scope of this review is to outline existing knowledge on innate immune responses involved in allergic airway inflammation, highlight current gaps in our understanding of the underlying molecular and cellular mechanisms and discuss the potential use of innate effector cells in new therapeutic avenues.

The Eosinophil in Infection

First described by Paul Ehrlich in 1879, who noted its characteristic staining by acidophilic dyes, for many years, the eosinophil was considered to be an end-effector cell associated with helminth infections and a cause of tissue damage. Over the past 30 years, research has helped to elucidate the complexity of the eosinophil's function and establish its role in host defense and immunity. Eosinophils express an array of ligand receptors which play a role in cell growth, adhesion, chemotaxis, degranulation, and cell-to-cell interactions. They play a role in activation of complement via both classical and alternative pathways. Eosinophils synthesize, store and secrete cytokines, chemokines, and growth factors. They can process antigen, stimulate T cells, and promote humoral responses by interacting with B cells. Eosinophils can function as antigen presenting cells and can regulate processes associated with both T1 and T2 immunity. Although long known to play a role in defense against helminth organisms, the interactions of eosinophils with these parasites are now recognized to be much more complex. In addition, their interaction with other pathogens continues to be investigated. In this paper, we review the eosinophil's unique biology and structure, including its characteristic granules and the effects of its proteins, our developing understanding of its role in innate and adaptive immunity and importance in immunomodulation, and the part it plays in defense against parasitic, viral, fungal and bacterial infections. Rather than our worst enemy, the eosinophil may, in fact, be one of the most essential components in host defense and immunity.

The Role of Neurotrophins in Inflammation and Allergy

Allergic inflammation is the result of a specific pattern of cellular and humoral responses leading to the activation of the innate and adaptive immune system, which, in turn, results in physiological and structural changes affecting target tissues such as the airways and the skin. Eosinophil activation and the production of soluble mediators such as IgE antibodies are pivotal features in the pathophysiology of allergic diseases. In the past few years, however, convincing evidence has shown that neurons and other neurosensory structures are not only a target of the inflammatory process but also participate in the regulation of immune responses by actively releasing soluble mediators. The main products of these activated sensory neurons are a family of protein growth factors called neurotrophins. They were first isolated in the central nervous system and identified as important factors for the survival and differentiation of neurons during fetal and postnatal development as well as neuronal maintenance later in life. Four members of this family have been identified and well defined: nerve growth factor, brain-derived neurotrophic factor, neurotrophin 3, and neurotrophin 4/5. Neurotrophins play a critical role in the bidirectional signaling mechanisms between immune cells and the neurosensory network structures in the airways and the skin. Pruritus and airway hyperresponsiveness, two major features of atopic dermatitis and asthma, respectively, are associated with the disruption of the neurosensory network activities. In this chapter, we provide a comprehensive description of the neuroimmune interactions underlying the pathophysiological mechanisms of allergic and inflammatory diseases.

Eosinophilic drug reactions detected by a prospective pharmacovigilance programme in a tertiary hospital

AIM

We conducted a prospective evaluation of all eosinophilic drug reactions (EDRs) through the Prospective Pharmacovigilance Program from Laboratory Signals at Hospital to find out the incidence and distribution of these entities in our hospital, their causative drugs, and predictors.

METHODS

All peripheral eosinophilia >700 × 10⁶  cells l^-1 detected at admission or during hospitalisation, were prospectively monitored over 42 months. The spectrum of the localised or systemic manifestation of EDR, the incidence, the distribution of causative drugs, and the predictors were analysed.

RESULTS

The incidence of EDR was 16.67 (95% Poisson confidence interval [CI]: 9.90-25.98) per 10 000 admissions. Of 274 cases of EDR, 154 (56.2%) cases in 148 patients were asymptomatic hypereosinophilia. In the remaining 120 (43.8%) cases, there was other involvement. Skin and soft tissue reactions were detected in 36 (13.1%) cases; visceral EDRs in 19(7.0%) cases; and drug-induced eosinophilic cutaneous and visceral manifestations were detected in the remaining 65 (23.7%) cases, 64 of which were potential drug reaction with eosinophilia and systemic symptoms (DRESS). After adjusting for age, sex, and hospitalisation wards, predictors of symptomatic eosinophilia were earlier onset of eosinophilia (hazard ratio [HR], 10.49; 95%CI: 3.13-35.16) higher eosinophil count (HR, 8.51; 95%CI: 3.28-22.08), and a delayed onset of corticosteroids (HR, 1.34; 95%CI: 1.01-1.73). A higher eosinophil count in patients with DRESS was significantly associated with greater impairment of liver function, prolonged hospitalisation, higher cumulative doses of corticosteroids, and if hypogammaglobinaemia was detected, a reactivation of human-herpesvirus 6 was subsequently detected.

CONCLUSIONS

Half (53.3%, 64/120 cases) of symptomatic EDRs were potential DRESS. The main predictor of severity of EDR was an early severe eosinophilia.