Eosinophils from Physiology to Disease: A Comprehensive Review

Cells of the Immune System in Cardiac Remodeling: Main Players in Resolution of Inflammation and Repair After Myocardial Infarction

The burden of heart failure (HF), developing after myocardial infarction MI, still represents a major issue in clinical practice. Failure of appropriate resolution of inflammation during post-myocardial injury is associated with unsuccessful left ventricular remodeling and underlies HF pathogenesis. Cells of the immune system have been shown to mediate both protective and damaging effects in heart remodeling. This ambiguity of the role of the immune system and inconsistent results of the recent clinical trials question the benefits of anti-inflammatory therapies during acute MI. The present review will summarize knowledge of the roles that different cells of the immune system play in the process of post-infarct cardiac healing. Data on the phenotype, active molecules and functions of the immune cells, based on the results of both experimental and clinical studies, will be provided. For some cellular subsets, such as macrophages, neutrophils, dendritic cells and lymphocytes, an anti-inflammatory activity has been attributed to the specific subpopulations. Activity of other cells, such as eosinophils, mast cells, natural killer (NK) cells and NKT cells has been shown to be highly dependent of the signals created by micro-environment. Also, new approaches for classification of cellular phenotypes based on the single-cell RNA sequencing allow better understanding of the phenotype of the cells involved in resolution of inflammation. Possible perspectives of immune-mediated therapy for AMI patients are discussed in the conclusion. We also outline unresolved questions that need to be solved in order to implement the current knowledge on the role of the immune cells in post-MI tissue repair into practice.

Severe cutaneous adverse reaction associated with antiseizure medications: Diagnosis, management, and prevention

Severe cutaneous adverse reactions (SCARs) are potentially life-threatening, with considerable morbidity and mortality. They are nonimmediate hypersensitivity reactions that occur in specifically predisposed patients with delayed T-cell-mediated hypersensitivity reaction. Antiseizure medications (ASMs) are among the drugs that can induce SCAR. Increased awareness of SCAR among clinicians treating patients with ASMs is critically important for early recognition of symptoms, prompt identification and removal of the causal drug, and early intervention to reduce SCAR-related acute and long-term morbidity and mortality. The diagnosis, management, and prevention of Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and drug reaction with eosinophilia and systemic symptoms (DRESS) are reviewed, along with the current understanding of the pathomechanisms and role of genetics in SCAR development. Supportive care and immunomodulating treatments for SCAR are discussed.

Anti-IL5 Drugs in COVID-19 Patients: Role of Eosinophils in SARS-CoV-2-Induced Immunopathology

SARS-CoV-2 infection stimulates a complex activation of the immune system. Eosinophils belong to the host’s defense equipment against respiratory viruses. In the first phase of the infection, eosinophils contribution is probably appropriate and beneficial, as they facilitate the suppression of the viral replication. However, in severe COVID-19 patients, during the second and third phases of the disease, eosinophils may participate in a maladaptive immune response and directly contribute to immunopathology. In fact, in severe patients, the immune response is prevalently T helper 1 type, but T helper 2 is also present. Eosinophils’ expansion and activation are stimulated by Type 2 cytokines, especially IL-5. Moreover, bronchial asthma, in which eosinophils play a central role, seems not to be a major risk factor for severe COVID-19. Among possible explanations, asthmatic patients are often treated with corticosteroids, which have been demonstrated to reduce the progression to critical COVID-19 in hospitalized patients. In addition to steroids, severe asthmatic patients are currently treated with biological drugs that target Type 2 immune response. Because IL-5 is necessary for the growth, survival, and activation of eosinophils, IL-5 inhibitors, such as mepolizumab, decrease the peripheral blood count of eosinophils, but do not influence eosinophils activation in the airway. In severe COVID-19 patients, the blockade of eosinophils’ activation might contrast harmful immunity.

Sequential Treatment of Sorafenib-Regorafenib Versus Sorafenib-Physician's Choice: A Propensity Score-Matched Analysis

BACKGROUND

Regorafenib has been shown to improve clinical outcomes compared to placebo, becoming a standard second-line therapy for sorafenib-progressed and -tolerated hepatocellular carcinoma (HCC) patients.

OBJECTIVE

We performed a multicentre, retrospective study in Italy and Korea to evaluate the effectiveness of the treatment sequence sorafenib-regorafenib compared with sorafenib and physician's choice in a real-life setting.

PATIENTS AND METHODS

A propensity score model was developed to control the results for baseline variable imbalances between the arm treated with sorafenib and regorafenib (S-R) and the arm treated with sorafenib and physician's choice (S-P). Survival analysis was conducted on the matched population.

RESULTS

After the application of propensity score matching, we analysed 99 patients in the arm treated with S-R and 99 patients in the arm treated with S-P. For the S-R group, the median overall survival was 22.2 months (95% CI 17.1-27.4), compared to 17.9 months (95% CI 15.1-50.0) for the S-P group. The results of the univariate analysis showed a 31% reduction of death risk for patients treated with S-R (p = 0.0382) compared to patients treated with S-P. Interaction tests highlighted the predictive role of alpha-fetoprotein (AFP), neutrophil-to-lymphocyte ratio (NLR), and extrahepatic spread.

CONCLUSION

This study provides additional proof of the superiority of the S-R treatment over the S-P treatment approach in advanced HCC patients from a real-life setting.

Blood Eosinophil Levels and Prognosis of Hospitalized Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

BACKGROUD

Studies about the clinical significance of high eosinophil levels in chronic obstructive pulmonary disease (COPD) are conflicting, and it has been less studied in hospitalized patients with acute exacerbation of COPD (AECOPD).This study was to examine blood eosinophil levels in relation to the prognosis of hospitalized patients with AECOPD.

METHODS

This was a retrospective cohort study of patients with AECOPD as their primary diagnosis and admitted to Beijing Shijitan Hospital, Capital Medical University, from January 2010 to December 2016. The patients were assigned according to the count of eosinophil in peripheral blood at their first hospitalization. Patients were grouped as ≤100, 100-300, and ≥300 eosinophils/µL of peripheral blood. The use of glucocorticoids, duration of hospitalization, in-hospital mortality, and re-hospitalization were examined.

RESULTS

Compared with the 100-300 eosinophils/µL group, the ≤100 eosinophils/µL group showed higher frequencies of fever, respiratory failure, and the use of systemic glucocorticoids. Eosinophil counts were not associated with in-hospital mortality and duration of hospitalization. The multivariable analysis showed that GOLD3/4 (odds ratio (OR)=2.04, 95%CI: 1.20-3.44, P = 0.008), systemic glucocorticoids (OR=1.84, 95%CI: 1.41-2.98, P = 0.012), mechanical ventilation (OR=2.66, 95%CI: 1.36-5.18, P = 0.004), and acute exacerbation in the past year before hospitalization (OR=2.03, 95%CI: 1.27-3.23, P = 0.003) were independently associated with acute exacerbation within 1 year after discharge. Eosinophil count was not associated with acute exacerbation within 1 year after discharge.

CONCLUSIONS

Peripheral blood eosinophil counts are not associated with the 1-year AECOPD prognosis.

Rapid effect of benralizumab in exacerbation of severe eosinophilic asthma associated with eosinophilic granulomatosis with polyangiitis

BACKGROUND

Eosinophilic granulomatosis with polyangiitis (EGPA) is a disease that is associated with severe uncontrolled eosinophilic asthma. Eosinophils play an important pathogenic role in the development of both diseases. Benralizumab is an antieosinophilic monoclonal antibody that binds to the α subunit of the human interleukin 5 receptor that is expressed on the surface of the eosinophil and basophil. We present the first case of rapid improvement in symptoms and lung function during admission for exacerbation of a severe eosinophilic asthma associated with EGPA.

CASE PRESENTATION

A 57-year-old man diagnosed with severe eosinophilic asthma associated to EGPA was admitted to the Pulmonology Department due to severe bronchospasm. At admission he presented 2300 eosinophils/µl. Despite intensive bronchodilator treatment, intravenous methylprednisolone at a dose of 80 mg/d, oxygen therapy, and budesonide nebulization, the patient continued to present daily episodes of bronchospasm. Ten days after admission, with blood eosinophil levels of 1700 cells/µl, benralizumab 30 mg sc was administered. That day, the Forced Expiratory Volume in the first second (FEV1) was 28% of the theoretical value (1150 ml). AT three days, FEV1 increased to 110 ml (31%). On the 9th day FEV1 was 51% (2100 ml). The blood eosinophil level on the 9th day was 0 cells/µl.

CONCLUSIONS

The rapid improvement of FEV1 is in line with studies based on clinical trials that found improvement after two days in peak flow and one phase II study that showed rapid response in exacerbation of asthma in the emergency room. The antieosinophilic effect at 24 h and the effect in different tissues determine the rapid improvement and the potential advantage of benralizumab in the treatment of EGPA. This case suggests the usefulness of benralizumab in patients with EGPA and eosinophilic severe asthma who show bronchospasm refractory to conventional treatment during a hospitalization due to asthma exacerbation.

Hematologic parameters as biomarkers for antihistamine and omalizumab resistance in chronic spontaneous urticaria

Background: Biomarkers of resistance to H₁-antihistamines (AH) and omalizumab in chronic spontaneous urticaria (CSU) are still a matter of debate. Objective: To identify clinical and laboratory attributes of the patient that may be predictive of AH and omalizumab resistance in CSU. Methods: We conducted a retrospective observational study by using the electronic patient record data base of patients with CSU and of sex- and age-matched controls. Patients with CSU were divided into three study groups: the CSU group, patients who responded to AHs; the antihistamine-resistant CSU (AH-CSU) group, patients refractory to a fourfold AH dose; and the control group, composed of a random sample of age- and sex-matched subjects, with a case-control ratio of 1:2. The patients in the AH-CSU group treated with omalizumab were compared according to the response or resistance to omalizumab. Results: A total of 106 subjects in the AH-CSU group, 483 in the CSU group, and 1198 in the control group were compared. Both AH-CSU (112.7 ± 43.1 kU/mL) and CSU (129.5 ± 52.4 kU/mL) groups were associated with higher plasma total IgE levels than control group (103.2 ± 49.5 kU/mL; p < 0.001). The AH-CSU group was characterized by a higher plasma high-sensitivity C-reactive protein level (6.4 ± 3.7 mg/L) than the CSU group (4.3 ± 1.4 mg/L; p < 0.001) and the control group (3.1 ± 1.8 mg/L; p < 0.001). The AH-CSU and CSU groups were characterized by a lower mean ± standard deviation basophil counts (0.18 ± 0.16 cells ×10⁹/L and 0.19 ± 0.11 cells ×10⁹/L, respectively) than the control group (0.22 ± 0.09 cells ×10⁹/L; p < 0.001). The mean platelet volume was higher in the AH-CSU group (11.2 ± 0.3 fL) than in the CSU group (11.1 ± 0.4 fL; p = 0.002) and in the control group (10.3 ± 0.4 fL; p < 0.001). There were no significant differences in the mean levels of lymphocytes, monocytes, eosinophils, basophils, and platelets, and the rates of eosinopenia and basopenia between the patients in the AH-CSU group who responded to and those who were resistant to omalizumab. Conclusion: This study provided additional data of interest to examine the pathophysiologic role of low-grade inflammation and basopenia in patients with CSU and resistant to AHs and omalizumab.

Mechanisms of toxicity mediated by neutrophil and eosinophil granule proteins

Neutrophils and eosinophils are granulocytes which are characterized by the presence of granules in the cytoplasm. Granules provide a safe storage site for granule proteins that play important roles in the immune function of granulocytes. Upon granulocytes activation, diverse proteins are released from the granules into the extracellular space and contribute to the fight against infections. In this article, we describe granule proteins of both neutrophils and eosinophils able to kill pathogens and review their anticipated mechanism of antimicrobial toxicity. It should be noted that an excess of granules protein release can lead to tissue damage of the host resulting in chronic inflammation and organ dysfunction.

Airway Redox Homeostasis and Inflammation Gone Awry: From Molecular Pathogenesis to Emerging Therapeutics in Respiratory Pathology

As aerobic organisms, we are continuously and throughout our lifetime subjected to an oxidizing atmosphere and, most often, to environmental threats. The lung is the internal organ most highly exposed to this milieu. Therefore, it has evolved to confront both oxidative stress induced by reactive oxygen species (ROS) and a variety of pollutants, pathogens, and allergens that promote inflammation and can harm the airways to different degrees. Indeed, an excess of ROS, generated intrinsically or from external sources, can imprint direct damage to key structural cell components (nucleic acids, sugars, lipids, and proteins) and indirectly perturb ROS-mediated signaling in lung epithelia, impairing its homeostasis. These early events complemented with efficient recognition of pathogen- or damage-associated recognition patterns by the airway resident cells alert the immune system, which mounts an inflammatory response to remove the hazards, including collateral dead cells and cellular debris, in an attempt to return to homeostatic conditions. Thus, any major or chronic dysregulation of the redox balance, the air-liquid interface, or defects in epithelial proteins impairing mucociliary clearance or other defense systems may lead to airway damage. Here, we review our understanding of the key role of oxidative stress and inflammation in respiratory pathology, and extensively report current and future trends in antioxidant and anti-inflammatory treatments focusing on the following major acute and chronic lung diseases: acute lung injury/respiratory distress syndrome, asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, and cystic fibrosis.

Prognostic Role of Blood Eosinophil Count in Patients with Sorafenib-Treated Hepatocellular Carcinoma

BACKGROUND

Inflammation is a long-established hallmark of liver fibrosis and carcinogenesis. Eosinophils are emerging as crucial components of the inflammatory process influencing cancer development. The role of blood eosinophils in patients with hepatocellular carcinoma receiving systemic treatment is an unexplored field.

OBJECTIVE

The objective of this study was to analyse the prognostic role of the baseline eosinophil count in patients with sorafenib-treated hepatocellular carcinoma.

PATIENTS AND METHODS

A training cohort of 92 patients with advanced- or intermediate-stage sorafenib-treated hepatocellular carcinoma and two validation cohorts of 65 and 180 patients were analysed. Overall survival and progression-free survival in relation to baseline eosinophil counts were estimated by the Kaplan-Meier method. Univariate and multivariate analyses were performed.

RESULTS

A negative prognostic impact of low baseline eosinophil counts (< 50*10⁹/L) was demonstrated in all cohorts (training cohort: hazard ratio = 50.1, 95% confidence interval 11.6-216.5, p < 0.0001 for low vs high eosinophil counts; first validation cohort: hazard ratio = 4.55, 95% confidence interval 1.24-16.65, p = 0.022; second validation cohort: hazard ratio = 3.21, 95% confidence interval 1.83-5.64, p < 0.0001). Moreover, low eosinophil counts had a negative prognostic role in patients progressing on or intolerant to sorafenib who received second-line regorafenib, but not capecitabine or best supportive care.

CONCLUSIONS

Our analysis identified baseline blood eosinophil counts as a new prognostic factor in patients with sorafenib-treated hepatocellular carcinoma. Concerning second-line therapies, eosinophil counts were associated with survival outcomes only in regorafenib-treated patients, suggesting a possible predictive role in this setting.

Eosinopenia as predictor of infection in patients admitted to an internal medicine ward: a cross-sectional study

Supplemental Digital Content is available in the text

Background:

The identification of infection in an internal medicine ward is crucial but not always straightforward. Eosinopenia has been proposed as a marker of infection, but specific cutoffs for prediction are not established yet. We aim to assess whether there is difference in eosinophil count between infected and noninfected patients and, if so, the best cutoffs to differentiate them.

Methods:

Cross-sectional, observational study with analysis of all patients admitted to an Internal Medicine Department during 2 consecutive months. Clinical, laboratory and imaging data were analyzed. Infection at hospital admission was defined in the presence of either a microbiological isolation or suggestive clinical, laboratory, and/or imaging findings. Use of antibiotics in the 8 days before hospital admission, presence of immunosuppression, hematologic neoplasms, parasite, or fungal infections were exclusion criteria. In case of multiple hospital admissions, only the first admission was considered.

Sensitivity and specificity values for eosinophils, leukocytes, neutrophils, and C-reactive protein were determined by receiver operating characteristic curve. Statistical analysis was performed with IBM SPSS Statistics® v25 and MedCalc Statistical Software® v19.2.3.

Results:

A total of 323 hospitalization episodes were evaluated, each corresponding to a different patient. One hundred fifteen patients were excluded. A total of 208 patients were included, 62.0% (n = 129) of them infected at admission. Ten patients had multiple infections.

Infected patients had fewer eosinophils than uninfected patients (15.8 ± 42 vs 71.1 ± 159 cell/mm³; P < .001). An eosinophil count at admission ≤69 cell/mm³ had a sensitivity of 89.1% and specificity of 54.4% (area under the curve 0.752; 95% confidence interval 0.682–0.822) for the presence of infection. Eosinophil count of >77 cells/mm³ had a negative likelihood ratio of 0.16.

Conclusions:

Eosinophil count was significantly lower in infected than in uninfected patients. The cutoff 69 cells/mm³ was the most accurate in predicting infection. Eosinophil count >77 cells/mm³ was a good predictor of absence of infection.

Associations of myeloperoxidase, interleukin-17A and heparin-binding EGF-like growth factor levels with in-stent restenosis after percutaneous coronary intervention: a single-centre case-control study in China

OBJECTIVES

To investigate the changes in serum myeloperoxidase (MPO), interleukin (IL)-17A and heparin-binding EGF-like growth factor (HB-EGF) levels before and after percutaneous coronary intervention (PCI), and to evaluate the associations of MPO, IL-17A and HB-EGF levels with the 1-year restenosis rate.

DESIGN

Case-control study.

SETTINGS

Xiangyang Central Hospital between January 2012 and December 2017.

PARTICIPANTS

Patients with coronary heart disease who underwent PCI.

INTERVENTIONS

Not applicable.

PRIMARY AND SECONDARY OUTCOME MEASURES

Not applicable.

RESULTS

Finally, 407 and 132 patients were included in the control and in-stent restenosis (ISR) groups, respectively. The general clinical characteristics of the patients were not significantly different between the two groups. The MPO, IL-17A and HB-EGF levels were not significantly different between the two groups at baseline but significantly increased after PCI. The ISR group showed higher levels of MPO, IL-17A and HB-EGF compared with the control group at all postoperative time points. Multivariable analysis showed that MPO, IL-17A and HB-EGF were associated with increased ISR [MPO (OR=1.003; 95% CI: 1.001 to 1.005; p=0.002), IL-17A (OR=1.015; 95% CI: 1.009 to 1.020; p<0.0001) and HB-EGF (OR=2.256; 95% CI: 1.103 to 4.009; p=0.002)]. All three factors had sensitivity and specificity ≥68% for ISR.

CONCLUSIONS

HB-EGF could be used for the detection of ISR after PCI and could be of use for the prediction of ISR, but the value of MPO and IL-17A might be more limited. This will have to be validated in future studies.

COVID-19: Are we dealing with a multisystem vasculopathy in disguise of a viral infection?

After the emergence of Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in the last two decades, the world is facing its new challenge in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic with unprecedented global response. With the expanding domain of presentations in COVID-19 patients, the full range of manifestations is yet to unfold. The classical clinical symptoms for SARS-CoV-2 affected patients are dry cough, high fever, dyspnoea, lethal pneumonia whereas many patients have also been found to be associated with a few additional signs and clinical manifestations of isolated vasculopathy. Albeit a deep and profound knowledge has been gained on the clinical features and management of COVID-19, less clear association has been provided on SARS-CoV-2 mediated direct or indirect vasculopathy and its possible correlation with disease prognosis. The accumulative evidences suggest that novel coronavirus, apart from its primary respiratory confinement, may also invade vascular endothelial cells of several systems including cerebral, cardio-pulmonary as well as renal microvasculature, modulating multiple visceral perfusion indices. Here we analyse the phylogenetic perspective of SARS-CoV-2 along with other strains of β-coronaviridae from a standpoint of vasculopathic derangements. Based on the existing case reports, literature and open data bases, we also analyse the differential pattern of vasculopathy related changes in COVID-19 positive patients. Besides, we debate the need of modulation in clinical approach from a hemodynamical point of view, as a measure towards reducing disease transmission, morbidity and mortality in SARS-CoV-2 affected patients.

Comparing the effects of whey and casein supplementation on nutritional status and immune parameters in patients with chronic liver disease: a randomised double-blind controlled trial

Protein supplementation may be beneficial for patients with chronic liver disease (CLD). This study compared the effects of whey protein isolate (WP) and casein (CA) supplementation on nutritional status and immune parameters of CLD patients who were randomly assigned to take 20 g of WP or CA twice per d as a supplement for 15 d. Body composition, muscle functionality and plasmatic immunomarkers were assessed before and after supplementation. Patients were also classified according to the model for end-stage liver disease (MELD) into less (MELD < 15) and more (MELD ≥ 15) severe disease groups. Malnutrition, determined by the Subjective Global Assessment at baseline, was observed in 57·4 % and 54·2 % of patients in the WP and CA groups, respectively (P = 0·649). Protein intake was lower at baseline in the WP group than in the CA group (P = 0·035), with no difference after supplementation (P = 0·410). Both the WP and CA MELD < 15 groups increased protein intake after supplementation according to the intragroup analysis. No differences were observed in body composition, muscle functionality, most plasma cytokines (TNF, IL-6, IL-1β and interferon-γ), immunomodulatory proteins (sTNFR1, sTNFR2, brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor) or immunomodulatory hormones (adiponectin, insulin and leptin) after supplementation in the WP groups at the two assessed moments. WP supplementation increased the levels of interferon-γ-induced protein-10/CXCL10 (P = 0·022), eotaxin-1/CCL11 (P = 0·031) and monocyte chemoattractant protein-1/CCL2 (P = 0·018) and decreased IL-5 (P = 0·027), including among those in the MELD ≥ 15 group, for whom IL-10 was also increased (P = 0·008). Thus, WP consumption by patients with CLD impacted the immunomodulatory responses when compared with CA with no impact on nutritional status.

Prognostic Significance of Immune Cell Populations Identified by Machine Learning in Colorectal Cancer Using Routine Hematoxylin and Eosin-Stained Sections

PURPOSE

Although high T-cell density is a well-established favorable prognostic factor in colorectal cancer, the prognostic significance of tumor-associated plasma cells, neutrophils, and eosinophils is less well-defined.

EXPERIMENTAL DESIGN

We computationally processed digital images of hematoxylin and eosin (H&E)-stained sections to identify lymphocytes, plasma cells, neutrophils, and eosinophils in tumor intraepithelial and stromal areas of 934 colorectal cancers in two prospective cohort studies. Multivariable Cox proportional hazards regression was used to compute mortality HR according to cell density quartiles. The spatial patterns of immune cell infiltration were studied using the GTumor:Immune cell function, which estimates the likelihood of any tumor cell in a sample having at least one neighboring immune cell of the specified type within a certain radius. Validation studies were performed on an independent cohort of 570 colorectal cancers.

RESULTS

Immune cell densities measured by the automated classifier demonstrated high correlation with densities both from manual counts and those obtained from an independently trained automated classifier (Spearman's ρ 0.71-0.96). High densities of stromal lymphocytes and eosinophils were associated with better cancer-specific survival [P trend < 0.001; multivariable HR (4th vs 1st quartile of eosinophils), 0.49; 95% confidence interval, 0.34-0.71]. High GTumor:Lymphocyte area under the curve (AUC0,20μm; P trend = 0.002) and high GTumor:Eosinophil AUC0,20μm (P trend < 0.001) also showed associations with better cancer-specific survival. High stromal eosinophil density was also associated with better cancer-specific survival in the validation cohort (P trend < 0.001).

CONCLUSIONS

These findings highlight the potential for machine learning assessment of H&E-stained sections to provide robust, quantitative tumor-immune biomarkers for precision medicine.

Hyper-Eosinophilic Syndrome Masquerading as Myocardial Infarction, Stroke and Cancer

Hyper-eosinophilic syndrome (HES) can be fatal if left untreated; and it is difficult to make a diagnosis early on due to the symptoms overlapping with many other conditions. For patients presenting with eosinophilia and end-organ damage, clinicians should have a high degree of suspicion for HES. Treatment with steroids can prevent further progression or can lead to complete resolution of the symptoms.

Immune cells as tumor drug delivery vehicles

This review article describes the use of immune cells as potential candidates to deliver anti-cancer drugs deep within the tumor microenvironment. First, the rationale of using drug carriers to target tumors and potentially decrease drug-related side effects is discussed. We further explain some of the current limitations when using nanoparticles for this purpose. Next, a comprehensive step-by-step description of the migration cascade of immune cells is provided as well as arguments on why immune cells can be used to address some of the limitations associated with nanoparticle-mediated drug delivery. We then describe the benefits and drawbacks of using red blood cells, platelets, granulocytes, monocytes, macrophages, myeloid-derived suppressor cells, T cells and NK cells for tumor-targeted drug delivery. An additional section discusses the versatility of nanoparticles to load anti-cancer drugs into immune cells. Lastly, we propose increasing the circulatory half-life and development of conditional release strategies as the two main future pillars to improve the efficacy of immune cell-mediated drug delivery to tumors.

Eosinophilic Colitis and Clostridioides difficile Sepsis With Rapid Remission After Antimicrobial Treatment; A Rare Coincidence and Its Pathogenic Implications

Eosinophilic colitis is a rare inflammatory disorder of the digestive tract with chronic evolution and unknown pathophysiological mechanisms. The article describes the case of a 64-year old woman with a history of asthma and hypereosinophilia, who presented to a surgical department for persistent abdominal pain in the past 4 months, weight loss and malabsorption. She was diagnosed with eosinophilic colitis based on the colonoscopic result indicating extensive eosinophilic infiltration of the colonic mucosa correlated with the laboratory data and abdominal CT scan results. Following the colonoscopy, the patient developed fever, hypotension and diarrhea and was transferred to an Infectious Diseases Department with a presumptive diagnosis of abdominal sepsis. Treatment with ertapenem was immediately started. Metronidazole was also added due to a PCR positive stool test for Clostridioides difficile toxins encoding-genes. The patient displayed a rapid remission of the fever and of the intestinal complaints following antibiotic therapy and was discharged after 14 days. During a 3 months follow-up, the patient remained asymptomatic with normal values of laboratory parameters except for a persistent hypereosinophilia. The case outlines two distinguishing features: a histopathologic diagnosis of eosinophilic colitis, a rare diagnosis of a patient with chronic abdominal pain and an unexpected and rapid remission of the eosinophilic colitis following the antibiotic treatment and the restoration of the intestinal eubiosis.

Eosinophils and Purinergic Signaling in Health and Disease

Eosinophils are major effector cells against parasites, fungi, bacteria, and viruses. However, these cells also take part in local and systemic inflammation, which are central to eczema, atopy, rhinitis, asthma, and autoimmune diseases. A role for eosinophils has been also shown in vascular thrombotic disorders and in cancer. Many, if not all, above-mentioned conditions involve the release of intracellular nucleotides (ATP, ADP, UTP, etc.) and nucleosides (adenosine) in the extracellular environment. Simultaneously, eosinophils further release ATP, which in autocrine and paracrine manners, stimulates P2 receptors. Purinergic signaling in eosinophils mediates a variety of responses including CD11b induction, ROI production, release of granule contents and enzymes, as well as cytokines. Exposure to extracellular ATP also modulates the expression of endothelial adhesion molecules, thereby favoring eosinophil extravasation and accumulation. In addition, eosinophils express the immunosuppressive adenosine P1 receptors, which regulate degranulation and migration. However, pro-inflammatory responses induced by extracellular ATP predominate. Due to their important role in innate immunity and tissue damage, pharmacological targeting of nucleotide- and nucleoside-mediated signaling in eosinophils could represent a novel approach to alleviate eosinophilic acute and chronic inflammatory diseases. These innovative approaches might also have salutary effects, particularly in host defense against parasites and in cancer.

Granulocyte-targeted therapies for airway diseases

The average respiration rate for an adult is 12-20 breaths per minute, which constantly exposes the lungs to allergens and harmful particles. As a result, respiratory diseases, which includes asthma, chronic obstructive pulmonary disease (COPD) and acute lower respiratory tract infections (LTRI), are a major cause of death worldwide. Although asthma, COPD and LTRI are distinctly different diseases with separate mechanisms of disease progression, they do share a common feature - airway inflammation with intense recruitment and activation of granulocytes and mast cells. Neutrophils, eosinophils, basophils, and mast cells are crucial players in host defense against pathogens and maintenance of lung homeostasis. Upon contact with harmful particles, part of the pulmonary defense mechanism is to recruit these cells into the airways. Despite their protective nature, overactivation or accumulation of granulocytes and mast cells in the lungs results in unwanted chronic airway inflammation and damage. As such, understanding the bright and the dark side of these leukocytes in lung physiology paves the way for the development of therapies targeting this important mechanism of disease. Here we discuss the role of granulocytes in respiratory diseases and summarize therapeutic strategies focused on granulocyte recruitment and activation in the lungs.

Analysis of Biochemical Parameters in Children with Chronic Tonsillitis

Chronic tonsillitis are frequent in pediatric pathology with numerous involved risk factors and pathogenic mechanisms. In this study, epidemiological data and biochemical values addressed to inflammation and mineral, lipid and hepatic metabolism were analyzed for 37 children of school age with chronic tonsillitis. We found that in the majority of cases, chronic tonsillitis was associated with increasing number of blood circulating inflammatory cells, high values of transaminases, cholesterol, triglycerides and low values of procalcitonin, C-reactive protein, calcium, vitamin D and serum iron. The results indicated relations of the biochemical profile analyzed with risk factors and systemic mechanisms for initiation and maintenance of chronic tonsillitis, aspects that can be used to optimize the prognosis of chronic tonsillitis in children.

Hypereosinophilic Syndrome, Multiorgan Involvement and Response to Imatinib

Hypereosinophilic syndrome (HES) is an uncommon syndrome characterized by peripheral blood eosinophils count of more than 1,500/mm³ with associated tissue damage. It can be either primary or secondary, for example, due to parasitic infections or inflammation.

We present a case of a 49-year-old Asian female with recurrent hospital admissions for cholecystitis, gastritis, urinary cystitis, and pancreatitis. Her peripheral blood count showed excessive eosinophils 15,600-19,000/mm³ on different occasions. Pathology of her gallbladder and her gastric biopsies showed eosinophilic infiltration. Her bone marrow biopsy showed a normocellular marrow with active trilineage hematopoiesis, eosinophilia, mild megakaryocytic hyperplasia with a few atypical forms, and mild T-cell lymphocytosis. Flow cytometry showed no evidence of acute leukemia, or T-cell or B-cell lymphoproliferative disorder. On fluorescent in-situ hybridization (FISH), myeloproliferative neoplasms (MPN) testing was negative for platelet-derived growth factor receptor-alpha (PDGFRA), platelet-derived growth factor receptor-beta (PDGFRB), and fibroblast growth factor receptor-1 (FGFR1) rearrangement. Despite not having the FIP1L1‐PDGFRA (factor interacting with PAPOLA and CPSF1-platelet-derived growth factor receptor, alpha polypeptide) gene fusion, our patient responded to the treatment with a significant decrease in her absolute eosinophils count and resolution of her symptoms.

Factors that affect blood eosinophil counts in a non-asthmatic population: Post hoc analysis of data from Brazil

Background

Improved understanding of the normal range of blood eosinophil counts (BEC) and conditions that influence them in non-asthmatic individuals should allow more accurate estimation of the threshold at which eosinophilic disease should be considered, diagnosed, and treated. This analysis investigated the impact of atopy, smoking, and parasitic infection on BEC.

Methods

This was a post hoc analysis of non-asthmatic subjects from a case-control study (CONEP 450/10) conducted at the Program for Control of Asthma in Bahia (ProAR). Participant BECs were measured at baseline; correlations between predefined risk factors and BEC were assessed via univariate and stratified analysis.

Results

Of the 454 participants included, 3% were helminth parasite-positive, 18% were non-helminth parasite-positive; and 450 had BEC data. The median (interquartile range [IQR]) BEC was 152 (96, 252) cells/μL. Any positive skin prick test, elevated total immunoglobulin E, allergic rhinitis, and being a current smoker were all individually associated with higher BEC (p < 0.05) compared with BEC in participants without these factors, but having a non-helminthic parasitic infection was not. Participants with all 4 risk factors that were associated with higher BEC had a median (IQR) BEC of 192 cells/μL (94, 416) versus 106 cells/μL (70, 164) for those with no risk factors.

Conclusions

In non-asthmatic subjects, atopy, allergic rhinitis, and current smoking status were associated with higher BEC compared with subjects without these factors, but BEC values were well below the threshold commonly accepted as normal. Therefore, BEC should be interpreted in the context of an individual's medical conditions and other BEC-influencing factors.

Influenza A virus directly modulates mouse eosinophil responses

Allergic asthma and influenza are common respiratory diseases with a high probability of co-occurrence. During the 2009 influenza pandemic, hospitalized patients with influenza experienced lower morbidity if asthma was an underlying condition. We have previously demonstrated that acute allergic asthma protects mice from severe influenza and have implicated eosinophils in the airways of mice with allergic asthma as participants in the antiviral response. However, very little is known about how eosinophils respond to direct exposure to influenza A virus (IAV) or the microenvironment in which the viral burden is high. We hypothesized that eosinophils would dynamically respond to the presence of IAV through phenotypic, transcriptomic, and physiologic changes. Using our mouse model of acute fungal asthma and influenza, we showed that eosinophils in lymphoid tissues were responsive to IAV infection in the lungs and altered surface expression of various markers necessary for cell activation in a niche-specific manner. Siglec-F expression was altered in a subset of eosinophils after virus exposure, and those expressing high Siglec-F were more active (IL-5Rα^hi CD62L^lo ). While eosinophils exposed to IAV decreased their overall transcriptional activity and mitochondrial oxygen consumption, transcription of genes encoding viral recognition proteins, Ddx58 (RIG-I), Tlr3, and Ifih1 (MDA5), were up-regulated. CD8⁺ T cells from IAV-infected mice expanded in response to IAV PB1 peptide-pulsed eosinophils, and CpG methylation in the Tbx21 promoter was reduced in these T cells. These data offer insight into how eosinophils respond to IAV and help elucidate alternative mechanisms by which they regulate antiviral immune responses during IAV infection.

Safety of Eosinophil-Depleting Therapy for Severe, Eosinophilic Asthma: Focus on Benralizumab

Eosinophils play a pivotal role in the inflammatory pathology of asthma and have been the target of new biologic treatments for patients with eosinophilic asthma. Given the central role of interleukin (IL)-5 in the eosinophil lifecycle, several therapies directed against the IL-5 pathway have been developed, including the anti-IL-5 antibodies mepolizumab and reslizumab and the IL-5 receptor α (IL-5Rα)-directed cytolytic antibody benralizumab. Eosinophil-depleting therapies represent a relatively new class of asthma treatment, and it is important to understand their long-term efficacy and safety. Eosinophils have been associated with host protection and tumor growth, raising potential concerns about the consequences of long-term therapies that deplete eosinophils. However, evidence for these associations in humans is conflicting and largely indirect or based on mouse models. Substantial prospective clinical trial and postmarketing data have accrued, providing insight into the potential risks associated with eosinophil depletion. In this review, we explore the current safety profile of eosinophil-reducing therapies, with particular attention to the potential risks of malignancies and severe infections and a focus on benralizumab. Benralizumab is an IL-5Rα-directed cytolytic monoclonal antibody that targets and efficiently depletes blood and tissue eosinophils through antibody-dependent cell-mediated cytotoxicity. Benralizumab is intended to treat patients with severe, uncontrolled asthma with eosinophilic inflammation. The integrated analyses of benralizumab safety data from the phase III SIROCCO and CALIMA trials and subsequent BORA extension trial for patients with asthma, and the phase III GALATHEA and TERRANOVA trials for patients with chronic obstructive pulmonary disease, form the principal basis for this review.

Successful treatment of a unique chronic multi-bacterial scalp infection with N-chlorotaurine, N-bromotaurine and bromamine T

Microbial species can act in synergy to circumvent environmental stress conditions and survive. In addition, biofilms are a serious public-health issue globally and constitute a clinical emergency. Infection persistence, increased morbidity and mortality, and antibiotic resistance are consequences of poly-microbial synergy. Due to inherited complexity and synergy between numerous species, newer antimicrobial agents of increased efficacy and tolerability are needed. In this unique medical case, a chronic (9 year) multi-bacterial scalp infection was differentially diagnosed from other inflammatory skin disorders by prolonged microbiological culture. The bacterial species found seem to have caused lesions of visible biofilm not documented previously in the medical literature. This complicated infection was treated successfully and rapidly with the combined topical application of the active halogen compounds N-chlorotaurine, N-bromotaurine and bromamine T, which is in contrast to the previous failed systemic and topical therapeutic approaches. This study strengthens the case for the use of active halogen compounds against multi-bacterial infections of the skin in the future, without the occurrence of resistance.

Blood Eosinophilia is an on-Treatment Biomarker in Patients with Solid Tumors Undergoing Dendritic Cell Vaccination with Autologous Tumor-RNA

Background: The approvals of immune checkpoint inhibitors for several cancer types and the rapidly growing recognition that T cell-based immunotherapy significantly improves outcomes for cancer patients led to a re-emergence of cancer vaccines, including dendritic cell (DC)-based immunotherapy. Blood and tissue biomarkers to identify responders and long-term survivors and to optimize cost and cost-effectiveness of treatment are greatly needed. We wanted to investigate whether blood eosinophilia is a predictive biomarker for patients with solid tumors receiving vaccinations with DCs loaded with autologous tumor-RNA. Methods: In total, 67 patients with metastatic solid tumors, who we treated with autologous monocyte-derived DCs transfected with total tumor mRNA, were serially analyzed for eosinophil counts and survival over the course of up to 14 years. Eosinophilic counts were performed on peripheral blood smears. Results: Up to 87% of the patients treated with DC-based immunotherapy experienced at least once an eosinophilia of ≥ 5% after initiation of therapy; 61 % reached levels of ≥ 10% eosinophils, and 13% of patients showed eosinophil counts of 20% or above. While prevaccination eosinophil levels were not associated with survival, patients with blood eosinophilia at any point after initiation of DC-based immunotherapy showed a trend towards longer survival. There was a statistically significant difference for the patients with eosinophil counts of 20% or more (p = 0.03). In those patients, survival was prolonged to a median of 58 months (range 2–111 months), compared to a median of 20 months (range 0–119 months) in patients with lower eosinophil counts. In 12% of the patients, an immediate increase in eosinophil count of at least 10 percentage points could be detected after the first vaccine, which also appeared to correlate with survival (65 vs. 24 months; p = 0.06). Conclusion: Blood eosinophilia appears to be an early, on-therapy biomarker in patients with solid tumors undergoing vaccination with RNA-transfected DC, specifically autologous tumor mRNA-transfected DC vaccines, and it correlates with long-term patient outcome. Eosinophilia should be systematically investigated in future trials.

The stability of blood Eosinophils in chronic obstructive pulmonary disease

Blood eosinophils are a predictive biomarker of inhaled corticosteroid response in chronic obstructive pulmonary disease (COPD). We investigated blood eosinophil stability over 1 year using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2019 thresholds of < 100, 100- < 300 and ≥ 300 eosinophils/μL in 225 patients from the COPDMAP cohort. Blood eosinophils showed good stability (rho: 0.71, p < 0.001, ICC 0.84), and 69.3% of patients remained in the same eosinophil category at 1 year. 85.3% of patients with eosinophils < 100 cells/μL had stable counts. The majority of blood eosinophil counts remain stable over 1 year using the GOLD 2019 thresholds.

The Role of Eosinophils in Immunotherapy

PURPOSE OF REVIEW

The purpose of this review is to provide a brief discussion on the differential diagnosis for peripheral eosinophilia. We will then focus on targeted immunotherapies for atopic disease, their effects on absolute peripheral eosinophil counts, and use of peripheral eosinophils as a predictor of treatment response.

RECENT FINDINGS

In atopic disease, lower absolute peripheral eosinophil counts are typically associated with improved outcomes. Much of the current evidence on eosinophils as a biomarker comes from post hoc analyses in therapeutic immunotherapy. While changes in eosinophilia were not the primary outcome of interest in many studies, some patterns did emerge. Cytolytic monoclonal antibodies AK002 and benralizumab completely reduce peripheral and tissue eosinophil numbers. Dupilumab may have paradoxical transient eosinophilia despite observed clinical efficacy. Atopic inflammation is complex largely due to the various cytokines which affect eosinophil activation, proliferation, differentiation, and survival. This demonstrates the challenges of using peripheral eosinophilia alone as a biomarker for atopic disease activity. More attention should spotlight how different immunotherapy modalities affect eosinophil-driven responses.

Two-Year Integrated Efficacy And Safety Analysis Of Benralizumab In Severe Asthma

Background

Benralizumab is an interleukin-5 receptor alpha–directed cytolytic monoclonal antibody. Treatment with benralizumab significantly reduces exacerbations and improves lung function after 1 year for patients with severe, uncontrolled eosinophilic asthma.

Objective

We explored whether benralizumab efficacy was sustained after an additional year of treatment while maintaining an acceptable safety profile.

Methods

Data from the pivotal 48-week SIROCCO and 56-week CALIMA studies were integrated with data from the predefined 56-week adult phase of the BORA extension study to provide a 2-year integrated efficacy and safety analysis of benralizumab. BORA enrolled patients who had completed SIROCCO or CALIMA. Patients receiving benralizumab 30 mg subcutaneously, either every 4 weeks (Q4W) or every 8 weeks (Q8W; first three doses Q4W), were assessed. Efficacy was evaluated based on baseline blood eosinophil counts from the pivotal studies (≥300 and <300 cells/μL).

Results

Mean treatment exposures were 24.3 (Q4W, n=518) and 24.6 (Q8W, n=512) months. Exacerbation frequency reductions observed in SIROCCO/CALIMA were maintained; 50% of the patients had no exacerbations during the 2-year study period (crude exacerbation rate, Q8W: 0.56 exacerbations/year for patients with blood eosinophil counts ≥300 cells/μL). Lung function improvements with benralizumab were maintained for 2 years, as represented by increases in mean prebronchodilator forced expiratory volume in 1 second from baseline of 0.343 L and 0.364 L with 1 and 2 years of benralizumab Q8W treatment, respectively, for patients with blood eosinophil counts ≥300 cells/μL. Health-related quality of life improvements with benralizumab observed in the pivotal studies were also sustained. Adverse events and serious adverse event rates were similar between the BORA extension and SIROCCO/CALIMA periods, with no new or unexpected occurrence of adverse events.

Conclusion

This benralizumab 2-year integrated analysis further supports long-term use of benralizumab for patients with severe, uncontrolled eosinophilic asthma.

Subcutaneous mepolizumab in children aged 6 to 11 years with severe eosinophilic asthma

OBJECTIVES

There are no published reports for anti-interleukin-5 therapy in children <12 years with asthma. The primary objective of this study was to characterize the pharmacokinetics and pharmacodynamics of mepolizumab following subcutaneous (SC) administration in children 6 to 11 years-of-age with severe eosinophilic asthma.

HYPOTHESIS

Mepolizumab SC pharmacokinetics and pharmacodynamics in children with severe eosinophilic asthma are comparable with adults.

STUDY DESIGN

Multinational, nonrandomised, open-label (NCT02377427).

PATIENT SELECTION

Children 6 to 11 years-of-age with severe eosinophilic asthma (blood eosinophil count ≥150 cells/µL at screening or ≥300 cells/µL <12 months of screening) and ≥2 exacerbations in the prior year.

METHODOLOGY

Children received mepolizumab SC 40 mg (bodyweight <40 kg) or 100 mg (≥40 kg) every 4 weeks for 12 weeks.

RESULTS

Thirty-six children received mepolizumab (40 mg, n = 26; 100 mg, n = 10). Mepolizumab exposures were higher and apparent clearance lower than predicted based on prior existing data. Derived mepolizumab exposures normalized to mean bodyweight for the 40 mg and 100 mg dose groups were 454 μg * day/mL and 675 μg * day/mL, respectively. At week 12, blood eosinophils were reduced by 89% and 83% from baseline to 42 and 55 cells/µL, respectively. Mepolizumab was well tolerated; no new safety signals were observed compared with previous adult/adolescent studies.

CONCLUSION

In children 6 to 11 years-of-age with severe eosinophilic asthma, mepolizumab SC 40 or 100 mg provided bodyweight-adjusted drug exposure within twofold of target adult exposure as well as marked reductions to blood eosinophil counts similar to adults, and although not designed to evaluate efficacy outcomes, demonstrated a positive clinical profile.

Diffuse Exfoliative Rash with Sepsis and Eosinophilia: A Case of Erythroderma?

<strong>BACKGROUND</strong> Erythroderma is an exfoliative dermatitis that manifests as generalized erythema and scaling that involves 90% of the body surface. If untreated, erythroderma can be fatal because of its metabolic burden and risk of secondary infections. <strong>CASE REPORT</strong> The patient was a 56-year-old male with prior rash attributed to group A Streptococcal cellulitis and discharged on Augmentin, Clindamycin with hydrocortisone cream, and Bactrim, but he had been noncompliant. He was admitted again for rash involving the face, torso, and extremities characterized by diffuse, desquamative, dry scales in morbilliform pattern. The patient was septic with <i>Staphylococcus aureus</i> bacteremia and compromised skin barrier. He was started on vancomycin and switched to Cefazolin IV due to concern for drug reaction. Autoimmune workup included antibodies for anti-Jo-1, anti-dsDNA, anti-centromere, and ANCA. However, only antinuclear antibody and scleroderma antibody were positive. Given the unclear workup results and lack of response to antibiotics, the patient was started on prednisone 60 mg PO and topical Triamcinolone 0.1% cream. A skin biopsy revealed psoriasiform hyperplasia with atypical T cell infiltrate and eosinophils, but negative for T cell gene rearrangement. The rash resolved after day 12 of application of topical Triamcinolone. <strong>CONCLUSIONS</strong> This case is unique in terms of the rarity of erythroderma and the diagnostic challenge given confounding factors such as noncompliance and drug reaction. Serious causes, such as SLE and cutaneous T cell lymphoma, were ruled out. Fortunately, the rash responded well to steroids; however, given the adverse effects of long-term use of topical steroids, the patient will need follow up with Dermatology.

Gut eosinophils and their impact on the mucus-resident microbiota

The gut has the largest commensal bacterial population in the body and its composition can be impacted by host factors such as production of immunoglobulin A (IgA). Eosinophils in the gut have been implicated in the production of antibacterial factors and maintenance of IgA‐secreting plasma cells. We used an eosinophil‐deficient mouse (∆dblGATA‐1^−/−) and littermate controls to investigate the role of eosinophils in the regulation of the microbiota, with particular emphasis on mucus‐resident species in the small and large intestine. We found no differences in IgA production or IgA‐expressing plasma cells between naive littermates in the small or large intestine. However, denaturing gel gradient electrophoresis revealed differences in the bacterial communities of the mucus and stools between wild‐type mice and ∆dblGATA‐1^−/− mice, with the greatest separation between the mucus microbial communities. Mucus‐resident bacteria in ∆dblGATA‐1^−/− mice had reduced diversity in the mucus compared with the stools. A quantitative PCR panel of selected bacteria showed that the most significant differences in the microbiota were between mucus‐resident bacteria and those in stool, such as the abundance of Clostridiales and Bacteroides. Our data implicate eosinophils in the regulation of the microbiota, especially the bacteria most hyperlocal to the gut barrier. Although we see differences between host genotypes in the overall microbial communities, further work is required to establish specifically which bacteria are different between these groups. Most importantly, the data revealed that the mucus and stool microbiota are discrete communities. Stool analysis alone may be insufficient to comprehensively explore and define the role of the gut microbiota in health and disease.

Human Peripheral Blood Eosinophils Express High Levels of the Purinergic Receptor P2X4

Extracellular nucleotides are important mediators of cell activation and trigger multiple responses via membrane receptors known as purinergic receptors (P2). P2X receptors are ligand-gated ion channels, activated by extracellular ATP. P2X4 is one of the most sensitive purinergic receptors, that is typically expressed by neurons, microglia, and some epithelial and endothelial cells. P2X4 mediates neuropathic pain via brain-derived neurotrophic factor and is also involved in inflammation in response to high ATP release. It is therefore involved in multiple inflammatory pathologies as well as neurodegenerative diseases. We have produced monoclonal antibodies (mAb) directed against this important human P2X4 receptor. Focusing on two mAbs, we showed that they also recognize mouse and rat P2X4. We demonstrated that these mAbs can be used in flow cytometry, immunoprecipitation, and immunohistochemistry, but not in Western blot assays, indicating that they target conformational epitopes. We also characterized the expression of P2X4 receptor on mouse and human peripheral blood lymphocytes (PBL). We showed that P2X4 is expressed at the surface of several leukocyte cell types, with the highest expression level on eosinophils, making them potentially sensitive to adenosine triphosphate (ATP). P2X4 is expressed by leucocytes, in human and mouse, with a significant gender difference, males having higher surface expression levels than females. Our findings reveal that PBL express significant levels of P2X4 receptor, and suggest an important role of this receptor in leukocyte activation by ATP, particularly in P2X4^high expressing eosinophils.

Targeting eosinophils: severe asthma and beyond

Recent research in the field of bronchial asthma has mainly focused on eosinophilic disease phenotype. Several trials proved the efficacy and safety profile of eosinophils and interleukin (IL)-5 targeting molecules, currently approved for severe asthma and available on the market. They include mepolizumab and reslizumab, IL-5 blocking molecules, and benralizumab, targeting the IL-5 receptor and eliciting a NK cell-mediated antibody-dependent cellular cytotoxicity against eosinophils. Eosinophilic inflammation represents the common pathophysiological background of several conditions, providing the rationale for the use of the same biologics beyond asthma. Although with different evidence grade, from clinical trials to case reports, anti-IL-5 biologics have been investigated in eosinophilic granulomatosis with polyangitis, allergic bronchopulmonary aspergillosis, chronic eosinophilic pneumonia, nasal polyposis, hypereosinophilic syndrome, and eosinophilic esophagitis. However, non-negligible differences between asthma and other eosinophilic diseases, particularly in eosinophils homing (blood and/or tissues), target organs and thus clinical features, probably account for the different response to the same drug in different clinical conditions and highlights the need for tailoring the therapeutic approach by modulating the drug dose and/or by combination therapy with multiple drugs. The optimal safety and tolerability profile of anti-IL-5 drugs warrants further and larger experimental and real-life investigations, which are needed especially in the field of non-asthma eosinophilic diseases. This review aims at summarizing the rationale for the use of biologics in eosinophilic diseases and their mechanisms of action. The current efficacy and safety evidence about eosinophils and IL-5 targeting molecules in asthma and in eosinophilic conditions beyond bronchi is also discussed.

The Dynamics of the Skin's Immune System

The skin is a complex organ that has devised numerous strategies, such as physical, chemical, and microbiological barriers, to protect the host from external insults. In addition, the skin contains an intricate network of immune cells resident to the tissue, crucial for host defense as well as tissue homeostasis. In the event of an insult, the skin-resident immune cells are crucial not only for prevention of infection but also for tissue reconstruction. Deregulation of immune responses often leads to impaired healing and poor tissue restoration and function. In this review, we will discuss the defensive components of the skin and focus on the function of skin-resident immune cells in homeostasis and their role in wound healing.

The Relationship of NADPH Oxidases and Heme Peroxidases: Fallin' in and Out

Peroxidase enzymes can oxidize a multitude of substrates in diverse biological processes. According to the latest phylogenetic analysis, there are four major heme peroxidase superfamilies. In this review, we focus on certain members of the cyclooxygenase-peroxidase superfamily (also labeled as animal heme peroxidases) and their connection to specific NADPH oxidase enzymes which provide H₂O₂ for the one- and two-electron oxidation of various peroxidase substrates. The family of NADPH oxidases is a group of enzymes dedicated to the production of superoxide and hydrogen peroxide. There is a handful of known and important physiological functions where one of the seven known human NADPH oxidases plays an essential role. In most of these functions NADPH oxidases provide H₂O₂ for specific heme peroxidases and the concerted action of the two enzymes is indispensable for the accomplishment of the biological function. We discuss human and other metazoan examples of such cooperation between oxidases and peroxidases and analyze the biological importance of their functional interaction. We also review those oxidases and peroxidases where this kind of partnership has not been identified yet.

Cocktail of Periodic Acid-Schiff and Papanicolaou: Novel staining technique for the identification of leukemic eosinophils - A pilot study

Background

Tissue eosinophilia may be caused due to reactive, neoplastic or idiopathic reasons. Reactive eosinophils in allergic and inflammatory conditions are transient and recruited from the circulation in response to various stimuli, whereas neoplastic eosinophils of leukemias and hematological malignancies are involved in the pathogenesis of the disease. The differentiation of reactive from neoplastic eosinophils has a serious implication on the treatment and prognosis of diseases. However, both these types of eosinophils display variation in morphology and staining characteristics in routine histopathology leading to a diagnostic dilemma.

Aim

The aim of this study is to evaluate the efficacy of special stains for the demonstration of eosinophils in normal/reactive lesions and leukemias.

Methodology

A retrospective study comprising twenty histologically diagnosed cases each of reactive oral lesions and leukemias were obtained from institutional archives. These tissue sections were subjected to staining with routine and special stains - Carbol chromotrope, Congo red, Leishman's stain, Periodic Acid-Schiff-papanicolaou (PAS-PAP) and PAS. Statistical analysis was performed using Pearson's Chi-square test to compare the various parameters in the evaluation of the staining efficacy.

Results

Carbol chromotrope and Congo red staining showed increased staining efficacy in normal/reactive eosinophils while PAS-PAP followed by PAS and Leishman's stain showed enhanced features such as homogenicity, specificity, increased staining intensity, enhanced nuclear and cytoplasmic details in leukemic eosinophils.

Conclusion

Combined PAS-PAP is a novel and cost-effective staining technique in differentiating reactive and leukemic eosinophils. It is significant in recognizing leukemic eosinophils of routine biopsies and alerts the clinician to rule out any underlying malignancies.

Eosinophilic colitis and colonic eosinophilia

PURPOSE OF REVIEW

Eosinophilic colitis is a rare condition, with a prevalence rate in the USA of 2-3/100 000 persons (0.003%), but diagnosed in 0.1% of biopsies in those colonoscoped for diarrhoea. Secondary colonic eosinophilia is more common and associated with systemic, colonic and infectious diseases. In this review, the latest advances in diagnosis, treatment and prognosis are summarized and discussed.

RECENT FINDINGS

What constitutes a 'normal' count of eosinophils is poorly documented but there are recent studies that establish normal colonic eosinophil ranges as well as distinguishing histological and clinical findings in primary eosinophilic colitis and secondary colonic eosinophilia in children and adults. Primary eosinophilic colitis is rare, relatively straightforward to diagnose, but may be difficult to treat. Colonic eosinophilia may be overt in parasite infection and connective tissue disease. More subtle, secondary colonic eosinophilia is a useful biomarker for gastrointestinal diseases, such as inflammatory bowel disease, colonic spirochaetosis and collagenous colitis, but the eosinophilia may more often be overlooked. A limited number of drugs are also known to cause left sided colonic eosinophilia such as clopidogrel, ibuprofen and oestroprogestinic agents.

SUMMARY

Advances in our understanding of primary eosinophilic colitis and secondary colonic eosinophilia is progressing and if present, colonic eosinophilia should point the clinician and pathologist to a list of differential diagnoses worth considering to direct optimal management.

Eosinophilia and Kidney Disease: More than Just an Incidental Finding?

Peripheral blood eosinophilia (PBE), defined as 500 eosinophils or above per microliter (µL) blood, is a condition that is not uncommon but often neglected in the management of patients with chronic kidney disease (CKD), acute kidney injury (AKI), or patients on renal replacement therapy (RRT). The nature of PBE in the context of kidney diseases is predominantly secondary or reactive and has to be distinguished from primary eosinophilic disorders. Nonetheless, the finding of persistent PBE can be a useful clue for the differential diagnosis of underdiagnosed entities and overlapping syndromes, such as eosinophilic granulomatosis with polyangiitis (EGPA), IgG4-related disease (IgG4-RD), acute interstitial nephritis (AIN), or the hypereosinophilic syndrome (HES). For patients on RRT, PBE may be an indicator for bio-incompatibility of the dialysis material, acute allograft rejection, or Strongyloides hyperinfection. In a subset of patients with EGPA, eosinophils might even be the driving force in disease pathogenesis. This improved understanding is already being used to facilitate novel therapeutic options. Mepolizumab has been licensed for the management of EGPA and is applied with the aim to abrogate the underlying immunologic process by blocking interleukin-5. The current article provides an overview of different renal pathologies that are associated with PBE. Further scientific effort is required to understand the exact role and function of eosinophils in these disorders which may pave the way to improved interdisciplinary management of such patients.

[Eosinopenia in 2018]

Since 1893, eosinopenia is a biological test to help a diagnosis of bacterial infection. Several publications have confirmed this hypothesis, particularly in the intensive care, pneumology and pediatric units. The value of this marker has been identified in vascular cerebral diseases and coronary bypass. Its contribution seems as relevant as procalcitonin, without extra cost. The diagnostic performance of this test was reinforced by a composite score (CIBLE score) that may improve its value in daily routine. Finally, monitoring eosinopenia appears to be a reliable mortality marker.

Post-viral atopic airway disease: pathogenesis and potential avenues for intervention

Introduction: In early childhood, wheezing due to lower respiratory tract illness is often associated with infection by commonly known respiratory viruses such as respiratory syncytial virus (RSV) and human rhinovirus (RV). How respiratory viral infections lead to wheeze and/or asthma is an area of active research. Areas covered: This review provides an updated summary of the published information on the development of post-viral induced atopy and asthma and the mechanisms involved. We focus on the contribution of animal models in identifying pathways that may contribute to atopy and asthma following respiratory virus infection, different polymorphisms that have been associated with asthma development, and current options for disease management and potential future interventions. Expert commentary: Currently there are no prophylactic therapies that prevent infants infected with respiratory viruses from developing asthma or atopy. Neither are there curative therapies for patients with asthma. Therefore, a better understanding of genetic factors and other associated biomarkers in respiratory viral induced pathogenesis is important for developing effective personalized therapies.

Leptin Elicits LTC4 Synthesis by Eosinophils Mediated by Sequential Two-Step Autocrine Activation of CCR3 and PGD2 Receptors

Leptin is a cytokine, produced mainly by mature adipocytes, that regulates the central nervous system, mainly to suppress appetite and stimulate energy expenditure. Leptin also regulates the immune response by controlling activation of immunomodulatory cells, including eosinophils. While emerging as immune regulatory cells with roles in adipose tissue homeostasis, eosinophils have a well-established ability to synthesize pro-inflammatory molecules such as lipid mediators, a key event in several inflammatory pathologies. Here, we investigated the impact and mechanisms involved in leptin-driven activation of eicosanoid-synthesizing machinery within eosinophils. Direct in vitro activation of human or mouse eosinophils with leptin elicited synthesis of lipoxygenase as well as cyclooxygenase products. Displaying selectivity, leptin triggered synthesis of LTC₄ and PGD₂, but not PGE₂, in parallel to dose-dependent induction of lipid body/lipid droplets biogenesis. While dependent on PI3K activation, leptin-driven eosinophil activation was also sensitive to pertussis toxin, indicating the involvement of G-protein coupled receptors on leptin effects. Leptin-induced lipid body-driven LTC₄ synthesis appeared to be mediated through autocrine activation of G-coupled CCR3 receptors by eosinophil-derived CCL5, inasmuch as leptin was able to trigger rapid CCL5 secretion, and neutralizing anti-RANTES or anti-CCR3 antibodies blocked lipid body assembly and LTC₄ synthesis induced by leptin. Remarkably, autocrine activation of PGD₂ G-coupled receptors DP1 and DP2 also contributes to leptin-elicited lipid body-driven LTC₄ synthesis by eosinophils in a PGD₂-dependent fashion. Blockade of leptin-induced PGD₂ autocrine/paracrine activity by a specific synthesis inhibitor or DP1 and DP2 receptor antagonists, inhibited both lipid body biogenesis and LTC₄ synthesis induced by leptin stimulation within eosinophils. In addition, CCL5-driven CCR3 activation appears to precede PGD₂ receptor activation within eosinophils, since neutralizing anti-CCL5 or anti-CCR3 antibodies inhibited leptin-induced PGD₂ secretion, while it failed to alter PGD₂-induced LTC₄ synthesis. Altogether, sequential activation of CCR3 and then PGD₂ receptors by autocrine ligands in response to leptin stimulation of eosinophils culminates with eosinophil activation, characterized here by assembly of lipidic cytoplasmic platforms synthesis and secretion of the pleiotropic lipid mediators, PGD₂, and LTC₄.