Eosinophil count in severe coronavirus disease 2019

Prognostic Performance of Inflammatory Biomarkers Based on Complete Blood Counts in COVID-19 Patients

With the end of the pandemic, COVID-19 has entered an endemic phase with expected seasonal spikes. Consequently, the implementation of easily accessible prognostic biomarkers for patients with COVID-19 remains an important area of research. In this monocentric study at a German tertiary care hospital, we determined the prognostic performance of different clinical and blood-based parameters in 412 COVID-19 patients. We evaluated the neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), pan-immune-inflammation value (PIV), and absolute eosinopenia (AEP, 0/µL) of COVID-19 patients (n = 412). The Siddiqui and Mehra staging proposal, the WHO clinical progression scale, and COVID-19-associated death were used as COVID-19 outcome measures. With respect to Siddiqi and Mehra staging, patient age of older than 75 years, high C-reactive protein (CRP), absolute eosinopenia (AEP), cardiovascular comorbidities, and high ferritin were significant independent predictors for severe COVID-19. When outcome was determined according to the WHO clinical progression scale, patient age of older than 75 years, high CRP, high LDH, AEP, high neutrophil-to-lymphocyte ratio (NLR), and the presence of pulmonal comorbidities were significant independent predictors for severe COVID-19. Finally, COVID-19-associated death was predicted independently by patient age of older than 75 years, high LDH, high NLR, and AEP. Eosinopenia (< 40/µL) was observed in 74.5% of patients, and AEP in almost 45%. In conclusion, the present real-world data indicate that the NLR is superior to more complex systemic immune-inflammation biomarkers (e.g., SII and PIV) in COVID-19 prognostication. A decreased eosinophil count emerged as a potential hallmark of COVID-19 infection, whereas AEP turned out to be an accessible independent biomarker for COVID-19 severity and mortality.

Are Lymphocytes and Eosinophils Associated with the COVID-19 Severity: A Large, Retrospective Study

OBJECTIVE

Coronavirus disease 2019 is an ongoing disease with high morbidity and mortality. We aimed to investigate the relationship between demographics, lymphocytes, eosinophils, and the coronavirus disease 2019 severity at hospital admission.

MATERIAL AND METHODS

A retrospective, observational cross-sectional study was carried out with 5828 coronavirus disease 2019 patients between March 11, 2020, and November 30, 2020. Patients were divided into 3 groups according to where they were followed up as an indicator of disease severity, namely outpatients, inpatients, and critically ill patients. The patients' demographics and hemogram values on admission were recorded. The predictive accuracies of lymphocyte count, lymphocyte percentage, eosinophil count, and eosinophil percentage for predicting severity were determined using receiver operating characteristic curves. Logistic regression analysis was used to predict intensive care unit demand according to lymphocyte and eosinophil values.

RESULTS

Of the 5828 coronavirus disease 2019 patients, 4050 were followed up as outpatients, 1581 were hospitalized in a ward, and 197 were hospitalized in the intensive care unit. Lymphocyte count and lymphocyte percentage were significantly different between the groups, but the difference for eosinophil count and eosinophil percentage was not significant as it was for lymphocytes. Cutoff values for lymphocyte count (1.0 × 109 /L), lymphocyte percentage (22%), eosinophil count (0.052 × 109 /L), and eosinophil percentage (0.08%) were found to indicate a high risk for intensive care unit admission. Coronavirus disease 2019 patients >55 years of age, with a lymphocyte count <1.0 × 109 /L, a lymphocyte percentage <22%, and an eosinophil percentage <0.08% had a 2-fold higher risk of requiring intensive care unit management.

CONCLUSION

Lymphocyte counts and percentages are quick and reliable biomarkers for predicting coronavirus disease 2019 severity and may guide physicians for proper management earlier.

Off-Label Benralizumab in Severe Non-Necrotizing Eosinophilic Vasculitis following Critical COVID-19 Disease and in DRESS

Benralizumab is a humanized recombinant mAb that binds to the interleukin 5 receptor (IL-5R) expressed on eosinophils and is approved for the treatment of severe eosinophilic asthma. There are a series of severe eosinophilic disorders that may benefit from this treatment, and it could be a life-saving therapy. In this paper, we present two severe patients with eosinophil-induced diseases that had a good resolution after one dose of Benralizumab 30 mg. The first case is a severe non-necrotizing eosinophilic vasculitis following critical COVID-19 disease and the second case is a DRESS (Drug Rash with Eosinophilia and Systemic Symptoms Syndrome) due to allopurinol. Conclusions: The successful administration of Benralizumab in rare or severe eosinophilic disease could be an option for life-saving therapies when conventional treatments fail.

Biomarker based biosensors: An opportunity for diagnosis of COVID-19

Early diagnosis and treatment of diseases are crucial research areas of human health. For early diagnosis, one method that has proven efficient is the detection of biomarkers which can provide real-time and accurate biological information. Most biomarker detection is currently carried out at localised dedicated laboratories using large and automated analysers, increasing waiting time and costs. Smaller, faster, and cheaper devices could potentially replace these time-consuming laboratory analyses and make analytical results available as point-of-care diagnostics. Innovative biosensor-based strategies could allow biomarkers to be tested reliably in a decentralised setting. Early diagnosis of COVID-19 patients has a key role in order to use quarantine and treatment strategies in a timely manner. Raised levels of several biomarkers in COVID-19 patients are associated with respiratory infections or dysfunction of various organs. Through clinical studies of COVID-19 patient biomarkers such as ferritin, Interleukins, albumin and …are found to reveals significant differences in their excretion ranges from healthy patients and patients with SARS-CoV-2, in addition to the development of biomarkers based biosensor such as stated biomarkers can be used and to investigate more specific biomarkers further proteomic analysis can be performed. This review presents several biomarker alterations in COVID-19 patients such as salivary, circulatory, coagulation, cardiovascular, renal, liver, C-reactive protein (CRP), immunological and inflammatory biomarkers. Also, biomarker sensors based on electrochemical, optical, and lateral flow characteristics which have potential applications for SARS-COV-2 in the recent COVID-19 pandemic, will be discussed.

Eotaxin-1 (CCL11) in neuroinflammatory disorders and possible role in COVID-19 neurologic complications

The related neurologic complications of SARS-CoV-2 infection in COVID-19 patients and survivors comprise symptoms including depression, anxiety, muscle pain, dizziness, headaches, fatigue, and anosmia/hyposmia that may continue for months. Recent studies have been demonstrated that chemokines have brain-specific attraction and effects such as chemotaxis, cell adhesion, modulation of neuroendocrine functions, and neuroinflammation. CCL11 is a member of the eotaxin family that is chemotactic agents for eosinophils and participate in innate immunity. Eotaxins may exert physiological and pathological functions in the central nerve system, and CCL11 may induce neuronal cytotoxicity effects by inducing the production of reactive oxygen species (ROS) in microglia cells. Plasma levels of CCL11 elevated in neuroinflammation and neurodegenerative disorders. COVID-19 patients display elevations in CCL11 levels. As CCL11 plays roles in physiosomatic and neuroinflammation, analyzing the level of this chemokine in COVID-19 patients during hospitalization and to predicting post-COVID-19-related neurologic complications may be worthwhile. Moreover, using chemokine modulators may be helpful in lessening the neurologic complications in such patients.

Chronic Rhinosinusitis and COVID-19

The COVID-19 pandemic has raised awareness about olfactory dysfunction, although a loss of smell was present in the general population before COVID-19. Chronic rhinosinusitis (CRS) is a common upper airway chronic inflammatory disease that is also one of the most common causes of olfactory dysfunction. It can be classified into different phenotypes (ie, with and without nasal polyps) and endotypes (ie, type 2 and non-type 2 inflammation). However, scientific information regarding CRS within the context of COVID-19 is still scarce. This review focuses on (1) the potential effects of severe acute respiratory syndrome coronavirus 2 infection on CRS symptoms, including a loss of smell, and comorbidities; (2) the pathophysiologic mechanisms involved in the olfactory dysfunction; (3) CRS diagnosis in the context of COVID-19, including telemedicine; (4) the protective hypothesis of CRS in COVID-19; and (5) the efficacy and safety of therapeutic options for CRS within the context of COVID-19.

Eosinopenia and increased markers of endothelial damage are characteristic of COVID-19 infection at time of hospital admission

In December 2019, a new virus has been discovered, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), leading to coronavirus disease 2019 (COVID-19). COVID-19 has been defined as an evolving disease with different phases. It starts with a mild or asymptomatic phase in which there is minimal disease. Thereafter, most patients recover, however, in 20% of the cases the infection worsens. It is hypothesized that eosinopenia, endothelial injury and the presence of smooth muscle autoantibodies are associated with the severity of the COVID-19. In a subset of 75 blood samples of patients with a SARS-CoV-2 infection at time of hospitalization and 30 healthy control samples concentrations of eosinophils, VEGF, VCAM, endothelin and smooth muscle autoantibodies were determined with hemocytometry, ELISA and immunofluorescence assays. In the group of patients with COVID-19 eosinophils (IQR = 0.0-0.01*10⁹/L) were significantly decreased (p < .001), whereas markers of endothelial damage VCAM (IQR = 740-1120 ng/mL) and endothelin (IQR = 2.0-3.4 pg/mL) were significantly increased (p < .001) compared to the group of healthy controls (eosinophils IQR = 0.09-0.19*10⁹/L, VCAM IQR = 362-561 ng/mL, endothelin IQR = 0.5-1.0 pg/mL). From the multivariate analysis, it is concluded that at time of hospitalization a combination of eosinopenia and increased markers of endothelial damage VCAM and endothelin are characteristic of COVID-19.

Activated CD8+CD38+ Cells Are Associated With Worse Clinical Outcome in Hospitalized COVID-19 Patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), that spread around the world during the past 2 years, has infected more than 260 million people worldwide and has imposed an important burden on the healthcare system. Several risk factors associated with unfavorable outcome were identified, including elderly age, selected comorbidities, immune suppression as well as laboratory markers. The role of immune system in the pathophysiology of SARS-CoV-2 infection is indisputable: while an appropriate function of the immune system is important for a rapid clearance of the virus, progression to the severe and critical phases of the disease is related to an exaggerated immune response associated with a cytokine storm. We analyzed differences and longitudinal changes in selected immune parameters in 823 adult COVID-19 patients hospitalized in the Martin University Hospital, Martin, Slovakia. Examined parameters included the differential blood cell counts, various parameters of cellular and humoral immunity (serum concentration of immunoglobulins, C4 and C3), lymphocyte subsets (CD3⁺, CD4⁺, CD8⁺, CD19⁺, NK cells, CD4⁺CD45RO⁺), expression of activation (HLA-DR, CD38) and inhibition markers (CD159/NKG2A). Besides already known changes in the differential blood cell counts and basic lymphocyte subsets, we found significantly higher proportion of CD8⁺CD38⁺ cells and significantly lower proportion of CD8⁺NKG2A⁺ and NK NKG2A⁺ cells on admission in non-survivors, compared to survivors; recovery in survivors was associated with a significant increase in the expression of HLA-DR and with a significant decrease of the proportion of CD8⁺CD38⁺cells. Furthermore, patients with fatal outcome had significantly lower concentrations of C3 and IgM on admission. However, none of the examined parameters had sufficient sensitivity or specificity to be considered a biomarker of fatal outcome. Understanding the dynamic changes in immune profile of COVID-19 patients may help us to better understand the pathophysiology of the disease, potentially improve management of hospitalized patients and enable proper timing and selection of immunomodulator drugs.

Pathological effects of SARS-CoV-2 on hematological and immunological cells: Alterations in count, morphology, and function

The novel Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), the causative agent of COVID-19 outbreak, spread rapidly and infected more than 140 million people with more than three million victims worldwide. The SARS-CoV-2 causes destructive changes in the immunological and hematological system of the host. These alterations appear to play a critical role in disease pathology and the emerging of clinical manifestations. In this review, we aimed to discuss the effect of COVID-19 on the count, function and morphology of immune and blood cells and the role of these changes in the pathophysiology of the disease. Knowledge of these changes may help with better management and treatment of COVID-19 patients.

Host Defence RNases as Antiviral Agents against Enveloped Single Stranded RNA Viruses

Owing to the recent outbreak of Coronavirus Disease of 2019 (COVID-19), it is urgent to develop effective and safe drugs to treat the present pandemic and prevent other viral infections that might come in the future. Proteins from our own innate immune system can serve as ideal sources of novel drug candidates thanks to their safety and immune regulation versatility. Some host defense RNases equipped with antiviral activity have been reported over time. Here, we try to summarize the currently available information on human RNases that can target viral pathogens, with special focus on enveloped single-stranded RNA (ssRNA) viruses. Overall, host RNases can fight viruses by a combined multifaceted strategy, including the enzymatic target of the viral genome, recognition of virus unique patterns, immune modulation, control of stress granule formation, and induction of autophagy/apoptosis pathways. The review also includes a detailed description of representative enveloped ssRNA viruses and their strategies to interact with the host and evade immune recognition. For comparative purposes, we also provide an exhaustive revision of the currently approved or experimental antiviral drugs. Finally, we sum up the current perspectives of drug development to achieve successful eradication of viral infections.

Ultra- and micro-structural changes of respiratory tracts in SARS-CoV-2 infected Syrian hamsters

The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) pandemic is causing a global crisis. It is still unresolved. Although many therapies and vaccines are being studied, they are still in their infancy. As this pandemic continues, rapid and accurate research for the development of therapies and vaccines is needed. Therefore, it is necessary to understand characteristics of diseases caused by SARS-CoV-2 through animal models. Syrian hamsters are known to be susceptible to SARS-CoV-2. They were intranasally inoculated with SARS-CoV-2. At 2, 4, 8, 12, and 16 days post-infection (dpi), these hamsters were euthanized, and tissues were collected for ultrastructural and microstructural examinations. Microscopic lesions were prominent in the upper and lower respiratory tracts from 2 and 4 dpi groups, respectively. The respiratory epithelium in the trachea, bronchiole, and alveolar showed pathological changes. Inflammatory cells including neutrophils, lymphocytes, macrophages, and eosinophils were infiltrated in/around tracheal lamina propria, pulmonary vessels, alveoli, and bronchiole. In pulmonary lesions, alveolar wall was thickened with infiltrated inflammatory cells, mainly neutrophils and macrophages. In the trachea, epithelial damages started from 2 dpi and recovered from 8 dpi, consistent with microscopic results, High levels of SARS-CoV-2 nucleoprotein were detected at 2 dpi and 4 dpi. In the lung, lesions were most severe at 8 dpi. Meanwhile, high levels of SARS-CoV-2 were detected at 4 dpi. Electron microscopic examinations revealed cellular changes in the trachea epithelium and alveolar epithelium such as vacuolation, sparse micro-organelle, and poor cellular margin. In the trachea epithelium, the number of cytoplasmic organelles was diminished, and small vesicles were prominent from 2 dpi. Some of these electron-lucent vesicles were filled with virion particles. From 8 dpi, the trachea epithelium started to recover. Because of shrunken nucleus and swollen cytoplasm, the N/C ratio of type 2 pneumocyte decreased at 8 and 12 dpi. From 8 dpi, lamellar bodies on type 2 pneumocyte cytoplasm were increasingly observed. Their number then decreased from 16 dpi. However, there was no significant change in type 1 pneumocyte. Viral vesicles were only observed in the cytoplasm of type 2 pneumocyte. In conclusion, ultra- and micro-structural changes presented in this study may provide useful information for SARS-CoV-2 studies in various fields.

Behavior of Eosinophil Counts in Recovered and Deceased COVID-19 Patients over the Course of the Disease

Knowledge about the immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, particularly regarding the function of eosinophils, has been steadily emerging recently. There exists controversy regarding the implications of eosinophils in the coronavirus disease 2019 (COVID-19)’s pathology. We report a retrospective cohort study including the comparison of leukocyte counts in COVID-19 patients, considering the outcomes of recovery (n = 59) and death (n = 60). Among the different types of leukocytes, the eosinophil counts were those that showed the greatest difference between recovered and deceased patients. Eosinopenia (eosinophil count < 0.01 × 10⁹/L) was more frequently observed in deceased than recovered patients (p = 0.0012). The eosinophil counts more rapidly increased and showed a greater proportion over the course of the disease in the recovered than deceased patients. Furthermore, the estimated survival rate was greater in patients without eosinopenia than in patients with eosinopenia (p = 0.0070) during hospitalization. Importantly, recovered but not deceased patients showed high negative correlations of the eosinophils with the neutrophil-to-lymphocyte ratio (NLR) and neutrophil counts at Day 9 of the onset of clinical symptoms (p ≤ 0.0220). Our analysis suggests that eosinopenia may be associated with unfavorable disease outcomes and that the eosinophils have a beneficial function in COVID-19 patients, probably contributing by controlling the exacerbated inflammation induced by neutrophils.

Altered Blood Cell Traits Underlie a Major Genetic Locus of Severe COVID-19

Background

The genetic locus 3p21.31 has been associated with severe coronavirus disease 2019 (COVID-19), but the underlying pathophysiological mechanism is unknown.

Methods

To identify intermediate traits associated with the 3p21.31 locus, we first performed a phenome-wide association study (PheWAS) with 923 phenotypes in 310,999 European individuals from the UK Biobank. For genes potentially regulated by the COVID-19 risk variant, we examined associations between their expression and the polygenic score (PGS) of 1,263 complex traits in a meta-analysis of 31,684 blood samples. For the prioritized blood cell traits, we tested their associations with age and sex in the same UK Biobank sample.

Results

Our PheWAS highlighted multiple blood cell traits to be associated with the COVID-19 risk variant, including monocyte count and percentage (p = 1.07×10 ^-8, 4.09×10 ^-13), eosinophil count and percentage (p = 5.73×10 ^-3, 2.20×10 ^-3), and neutrophil percentage (p = 3.23×10 ^-3). The PGS analysis revealed positive associations between the expression of candidate genes and genetically predicted counts of specific blood cells: CCR3 with eosinophil and basophil (p = 5.73×10 ^-21, 5.08×10 ^-19); CCR2 with monocytes (p = 2.40×10 ^-10); and CCR1 with monocytes and neutrophil (p = 1.78×10 ^-6, 7.17×10 ^-5). Additionally, we found that almost all examined white blood cell traits are significantly different across age and sex groups.

Conclusions

Our findings suggest that altered blood cell traits, especially those of monocyte, eosinophil, and neutrophil, may represent the mechanistic links between the genetic locus 3p21.31 and severe COVID-19. They may also underlie the increased risk of severe COVID-19 in older adults and men.

Association between the peripheral blood eosinophil counts and COVID-19: A meta-analysis

BACKGROUND

The conclusions about the relationship between eosinophil counts and the severity of coronavirus disease 2019 (COVID-19) were controversial, so we updated the evidences and reassessed it.

METHODS

We searched the PubMed, Cochrane library, Excerpta Medica Database, and Web of Science to compare the eosinophil counts about non-severe disease group (mild pneumonia, moderate pneumonia, non-critical disease and recovery group) and severe disease group (severe pneumonia, critical pneumonia, critical disease and death group) in COVID-19.

RESULTS

A total of 1228 patients from 10 studies were included. Compared with non-severe group, severe group had strikingly lower average eosinophil counts (SMD 0.65, 95% confidence intervals [CI] 0.29-1.01; P < .001). The result of subgroup analysis of different countries showed SMD 0.66, 95% CI 0.26-1.06; P < .001. Another subgroup analysis between mild-moderate pneumonia versus severe-critical pneumonia showed SMD 0.69, 95% CI 0.25-1.13; P < .001, and no significant risk of publication bias (Begg test 0.063 and Egger test 0.057) in this subgroup. The heterogeneity was substantial, but the sensitivity analyses showed no significant change when individual study was excluded, which suggested the crediblity and stablity of our results.

CONCLUSIONS

The eosinophil counts had important value as an indicator of severity in patients with COVID-19.

PROSPERO REGISTRATION NUMBER

CRD42020205497.

Mast Cell and Eosinophil Activation Are Associated With COVID-19 and TLR-Mediated Viral Inflammation: Implications for an Anti-Siglec-8 Antibody

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 infection represents a global health crisis. Immune cell activation via pattern recognition receptors has been implicated as a driver of the hyperinflammatory response seen in COVID-19. However, our understanding of the specific immune responses to SARS-CoV-2 remains limited. Mast cells (MCs) and eosinophils are innate immune cells that play pathogenic roles in many inflammatory responses. Here we report MC-derived proteases and eosinophil-associated mediators are elevated in COVID-19 patient sera and lung tissues. Stimulation of viral-sensing toll-like receptors in vitro and administration of synthetic viral RNA in vivo induced features of hyperinflammation, including cytokine elevation, immune cell airway infiltration, and MC-protease production—effects suppressed by an anti-Siglec-8 monoclonal antibody which selectively inhibits MCs and depletes eosinophils. Similarly, anti-Siglec-8 treatment reduced disease severity and airway inflammation in a respiratory viral infection model. These results suggest that MC and eosinophil activation are associated with COVID-19 inflammation and anti-Siglec-8 antibodies are a potential therapeutic approach for attenuating excessive inflammation during viral infections.

Risk factors for severe and critically ill COVID-19 patients: A review

The pandemic of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused an unprecedented global social and economic impact, and high numbers of deaths. Many risk factors have been identified in the progression of COVID-19 into a severe and critical stage, including old age, male gender, underlying comorbidities such as hypertension, diabetes, obesity, chronic lung diseases, heart, liver and kidney diseases, tumors, clinically apparent immunodeficiencies, local immunodeficiencies, such as early type I interferon secretion capacity, and pregnancy. Possible complications include acute kidney injury, coagulation disorders, thoromboembolism. The development of lymphopenia and eosinopenia are laboratory indicators of COVID-19. Laboratory parameters to monitor disease progression include lactate dehydrogenase, procalcitonin, high-sensitivity C-reactive protein, proinflammatory cytokines such as interleukin (IL)-6, IL-1β, Krebs von den Lungen-6 (KL-6), and ferritin. The development of a cytokine storm and extensive chest computed tomography imaging patterns are indicators of a severe disease. In addition, socioeconomic status, diet, lifestyle, geographical differences, ethnicity, exposed viral load, day of initiation of treatment, and quality of health care have been reported to influence individual outcomes. In this review, we highlight the scientific evidence on the risk factors of severity of COVID-19.

Expression of SARS-CoV-2 Host Cell Entry Factors in Immune System Components of Healthy Individuals and Its Relevance for COVID-19 Immunopathology

Intense immunological dysregulation including immune cell lesions has been characteristically observed in severe cases of coronavirus disease-2019 (COVID-19), for which molecular mechanisms are not properly understood. A study of physiological expressions of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) host cell entry-related factors in immune system components may help explain molecular mechanisms involved in COVID-19 immunopathology. We analyzed transcriptomic and proteomic expression metadata for SARS-CoV-2 host cell entry receptor ACE2 and entry associated proteases (TMPRSS2, CTSL, and FURIN) in silico across immune system components including the blood lineage cells. ACE2 was not detected in any of the studied immune cell components; however, varying transcriptomic and proteomic expressions were observed for TMPRSS2, CTSL, and FURIN. Nondetectable expressions of SARS-CoV-2 host cell entry receptor ACE2 in immune system components or blood lineage cells indicate it does not mediate immune cell lesions in COVID-19. Alternative mechanisms need to be explored for COVID-19 immunopathogenesis.

The Prognostic Value of Eosinophil Recovery in COVID-19: A Multicentre, Retrospective Cohort Study on Patients Hospitalised in Spanish Hospitals

Objectives: A decrease in blood cell counts, especially lymphocytes and eosinophils, has been described in patients with serious Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), but there is no knowledge of their potential role of the recovery in these patients’ prognosis. This article aims to analyse the effect of blood cell depletion and blood cell recovery on mortality due to COVID-19. Design: This work was a retrospective, multicentre cohort study of 9644 hospitalised patients with confirmed COVID-19 from the Spanish Society of Internal Medicine’s SEMI-COVID-19 Registry. Setting: This study examined patients hospitalised in 147 hospitals throughout Spain. Participants: This work analysed 9644 patients (57.12% male) out of a cohort of 12,826 patients ≥18 years of age hospitalised with COVID-19 in Spain included in the SEMI-COVID-19 Registry as of 29 May 2020. Main outcome measures: The main outcome measure of this work is the effect of blood cell depletion and blood cell recovery on mortality due to COVID-19. Univariate analysis was performed to determine possible predictors of death, and then multivariate analysis was carried out to control for potential confounders. Results: An increase in the eosinophil count on the seventh day of hospitalisation was associated with a better prognosis, including lower mortality rates (5.2% vs. 22.6% in non-recoverers, OR 0.234; 95% CI, 0.154 to 0.354) and lower complication rates, especially regarding the development of acute respiratory distress syndrome (8% vs. 20.1%, p = 0.000) and ICU admission (5.4% vs. 10.8%, p = 0.000). Lymphocyte recovery was found to have no effect on prognosis. Treatment with inhaled or systemic glucocorticoids was not found to be a confounding factor. Conclusion: Eosinophil recovery in patients with COVID-19 who required hospitalisation had an independent prognostic value for all-cause mortality and a milder course.

Evaluation of eosinopenia as a diagnostic and prognostic indicator in COVID-19 infection

INTRODUCTION

Eosinopenia has been observed during infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19. This study evaluated the role of eosinopenia as a diagnostic and prognostic indicator in COVID-19 infection.

METHODS

Information on 429 patients with confirmed COVID-19, admitted to Apollo Hospitals, Chennai, India between 04 June 2020 to 15 August 2020, was retrospectively collected through electronic records and analysed.

RESULTS

79.25% of the patients included in the study had eosinopenia on admission. The median eosinophil count in COVID-19-positive patients was 0.015 × 10⁹ /L, and in negative patients, it was 0.249 × 10⁹ /L. Eighteen per cent of the positive patients presented with 0 eosinophil count. Eosinopenia for early diagnosis of COVID-19 had a sensitivity of 80.68% and specificity of 100% with an accuracy of 85.24. Role of eosinopenia in prognostication of COVID-19 was found to be insignificant. There was no statistically significant difference between the median eosinophil counts in survivors and nonsurvivors. Eosinophil trends during the course of disease were found to be similar between survivors and nonsurvivors.

CONCLUSIONS

Eosinopenia on admission is a reliable and convenient early diagnostic marker for COVID-19 infection, helping in early identification, triaging and isolation of the patients till nucleic acid test results are available. Role of eosinopenia as a prognostic indicator is insignificant.

"NETs and EETs, a Whole Web of Mess"

Neutrophils and eosinophils are granulocytes that have very distinct functions. Neutrophils are first responders to external threats, and they use different mechanisms to control pathogens. Phagocytosis, reactive oxygen species, and neutrophil extracellular traps (NETs) are some of the mechanisms that neutrophils utilize to fight pathogens. Although there is some controversy as to whether NETs are in fact beneficial or detrimental to the host, it mainly depends on the biological context. NETs can contribute to disease pathogenesis in certain types of diseases, while they are also undeniably critical components of the innate immune response. On the contrary, the role of eosinophils during host immune responses remains to be better elucidated. Eosinophils play an important role during helminthic infections and allergic responses. Eosinophils can function as effector cells in viral respiratory infections, gut bacterial infections, and as modulators of immune responses by driving the balance between Th1 and Th2 responses. In particular, eosinophils have biological activities that appear to be quite similar to those of neutrophils. Both possess bactericidal activity, can activate proinflammatory responses, can modulate adaptive immune responses, can form extracellular traps, and can be beneficial or detrimental to the host according to the underlying pathology. In this review we compare these two cell types with a focus on highlighting their numerous similarities related to extracellular traps.

Clinical Outcome of Eosinophilia in Patients with COVID-19: A Controlled Study

Background:

Eosinophils can be considered as multifunctional leukocytes that contribute to various physiological and pathological processes depending on their location and activation status. There are emerging eosinophil-related considerations concerning COVID-19. Variable eosinophil counts have been reported during COVID-19. Whether these changes are related to the primary disease process or due to immunomodulation induced by the treatment has not yet been elucidated.

Aim of the study:

To describe changes in the differential leukocyte counts including eosinophils, in a cohort of symptomatic patients with confirmed COVID-19 and to correlate these changes, if any, with the severity of the disease.

Patients and methods:

We recorded the clinical data, lab findings, including inflammatory markers and leukocyte and differential count, course of the disease and severity score in 314 confirmed symptomatic cases of COVID-19.

Results:

Laboratory tests revealed that 28.7 % (n =86) had mild eosinophilia (eosinophil count > 500 <1,500/µL). Thirty-four patients (11.3%) had elevated absolute neutrophil count (ANC) (>8,000/µL), and 7 (2.3%) had decreased ANC (< 1,500/µl). Seven patients (2.3%) had lymphopenia (<1,000/µL) and 4 (4.67%) had lymphocytosis (> 4,000/µL). C-reactive protein (CRP) was elevated in 83 patients (27.6%). Chest X-Ray changes included: increased broncho vascular markings (38%), ground-glass opacity (GGO) pneumonitis (19.3%), lobar consolidation (5%), bronchopneumonia (8.3%), nodular opacity (1%), acute respiratory distress syndrome (ARDS) (2.3%), pleural effusion (1.0%) and other atypical findings (6.6%). Patients with eosinophilia had significantly lower CRP, and lower % of GGO, lobar and bronchopneumonia and ARDS in their chest images compared to patients without eosinophilia (p: <0.05). They also had a lower requirement for a hospital stay, ICU admission, mechanical ventilation, and oxygen supplementation versus patients without eosinophilia (p: <0.05). The eosinophils count was correlated negatively with the duration of ICU admission, mechanical ventilation, and oxygen supplementation and with CRP level (r: - 0.34, -0.32, -0.61 and - 0.39, respectively) (p: < 0.01).

Conclusions:

Our study reports a relatively high prevalence of eosinophilia in symptomatic COVID-19 positive patients. Patients with eosinophilia had a lower level of CRP, milder clinical course and better disease outcomes compared to those without eosinophilia. Our findings indicated a protective role of eosinophils in mitigating the severity of inflammatory diseases through an inhibitory mechanism, as evidenced by lower CRP. This protective role of eosinophils needs to be validated by further prospective studies. (www.actabiomedica.it)

Immunology of COVID-19: Mechanisms, clinical outcome, diagnostics, and perspectives-A report of the European Academy of Allergy and Clinical Immunology (EAACI)

With the worldwide spread of the novel severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) resulting in declaration of a pandemic by the World Health Organization (WHO) on March 11, 2020, the SARS‐CoV‐2‐induced coronavirus disease‐19 (COVID‐19) has become one of the main challenges of our times. The high infection rate and the severe disease course led to major safety and social restriction measures worldwide. There is an urgent need of unbiased expert knowledge guiding the development of efficient treatment and prevention strategies. This report summarizes current immunological data on mechanisms associated with the SARS‐CoV‐2 infection and COVID‐19 development and progression to the most severe forms. We characterize the differences between adequate innate and adaptive immune response in mild disease and the deep immune dysfunction in the severe multiorgan disease. The similarities of the human immune response to SARS‐CoV‐2 and the SARS‐CoV and MERS‐CoV are underlined. We also summarize known and potential SARS‐CoV‐2 receptors on epithelial barriers, immune cells, endothelium and clinically involved organs such as lung, gut, kidney, cardiovascular, and neuronal system. Finally, we discuss the known and potential mechanisms underlying the involvement of comorbidities, gender, and age in development of COVID‐19. Consequently, we highlight the knowledge gaps and urgent research requirements to provide a quick roadmap for ongoing and needed COVID‐19 studies.

Biomarkers associated with COVID-19 disease progression

The coronavirus disease 2019 (COVID-19) pandemic is a scientific, medical, and social challenge. The complexity of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is centered on the unpredictable clinical course of the disease that can rapidly develop, causing severe and deadly complications. The identification of effective laboratory biomarkers able to classify patients based on their risk is imperative in being able to guarantee prompt treatment. The analysis of recently published studies highlights the role of systemic vasculitis and cytokine mediated coagulation disorders as the principal actors of multi organ failure in patients with severe COVID-19 complications. The following biomarkers have been identified: hematological (lymphocyte count, neutrophil count, neutrophil-lymphocyte ratio (NLR)), inflammatory (C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), procalcitonin (PCT)), immunological (interleukin (IL)-6 and biochemical (D-dimer, troponin, creatine kinase (CK), aspartate aminotransferase (AST)), especially those related to coagulation cascades in disseminated intravascular coagulation (DIC) and acute respiratory distress syndrome (ARDS). New laboratory biomarkers could be identified through the accurate analysis of multicentric case series; in particular, homocysteine and angiotensin II could play a significant role.

Clinical Characteristics and Eosinophils in Young SARS-CoV-2-Positive Chinese Travelers Returning to Shanghai

Background: The COVID-19 outbreak, which was first reported in Wuhan, China, in December 2019, began to spread throughout the world, and now involves over 200 countries.

Methods: A total of 37 overseas young and middle-aged people, who tested as SARS-CoV-2 positive upon their return to Shanghai, were enrolled for an analysis of their clinical symptoms, blood routine indexes, and lung CT images.

Results: The clinical symptoms were characterized by fever (51.4%), dry cough (13.5%), expectoration (27.0%), hypodynamia (21.6%), pharyngalia (10.8%), pharynoxerosis (8.1%), rhinobyon (13.5%), rhinorrhea (8.1%), muscular soreness (16.2%), and diarrhea (2.7%). In 16.2% of cases, no symptoms were reported. Fever was the most common symptom (51.40%). The pneumonic changes referred to the latticed ground glass imaging and similar white lung imaging accompanied by consolidated shadows. The rate of pneumonia was high (81.10%). We found that the exclusive percent of eosinophils was abnormally low. By analyzing the correlation of eosinophils, fever, and pneumonia, we found that the percentage of eosinophils was low in the COVID-19 patients afflicted with fever or pneumonia (P < 0.01). Additionally, pneumonia and fever were negatively correlated with the percentage of eosinophils and eosinophils/neutrophils ratio (P < 0.01, respectively), but not associated with pneumonia severity (P > 0.05). Fever was not correlated with pneumonia (P > 0.05).

Conclusion: A low percentage of eosinophils may be considered as a biomarker of pneumonia of COVID-19, but not as a biomarker of pneumonia severity.

Immune Parameters and COVID-19 Infection - Associations With Clinical Severity and Disease Prognosis

Severe acute respiratory syndrome caused by a novel 2019 coronavirus (SARS-CoV2) represents one of the most studied infectious diseases of today. The number of scientific reports and publications increases exponentially day by day. While the majority of infected subjects are asymptomatic or show mild symptoms, there is an important proportion of patients who requires hospitalization and, sometimes, intensive care. Immune response to novel coronavirus is complex, involves both innate and adaptive immunity, and is biphasic. Significant differences were observed when comparing severe and non-severe patients. Analysis of the reported results from clinical trials clearly show an involvement of specific cellular immunity (predominantly leucopenia, decreased counts of CD3+, CD4+, and CD8+ T lymphocytes, changes of T cell compartment) and the so-called cytokine storm, which is associated with worsening of symptoms and the promotion of lung damage. An interesting finding regarding eosinopenia that can have both diagnostic and prognostic value is reported by some authors. Examination of selected immune parameters could help to identify severe patients with the risk of unfavorable course of the disease, predict the prognosis and recognize improvement in the clinical status. Moreover, detailed analysis of the immune changes could help to select novel prospective therapeutic strategies.

COVID-19 Infection and Haematological Involvement: a Review of Epidemiology, Pathophysiology and Prognosis of Full Blood Count Findings. ACTA ACUST UNITED AC. 2020;1-5. [PMID: 32838152 PMCID: PMC7323879 DOI: 10.1007/s42399-020-00380-3]

The unfolding COVID-19 pandemic began in December 2019 in Wuhan, Hubei Province. COVID-19 is a systemic infection affecting several systems including the haematopoietic system. Surveys illustrating the laboratory findings of these patients conclude that lymphocytopenia, neutrophilia and thrombocytopenia are prominent amongst them. Moreover, it has been reported a significant decrease in T lymphocyte subsets and an increase of inflammatory cytokines of hospitalized patients with COVID-19. Generally, thrombocytopenia is commonplace in critically ill patients and usually suggests serious organ malfunction. In view of this, this review investigates the correlation between these abnormalities and the prognosis and disease course. Full blood count is an easy, economic and widely available tool which may help to discriminate between patients with or without severe disease. Last but not least, this review examines potential pathophysiological mechanisms by the novel coronavirus which contribute to these haematological alterations aiding the clinicians to better understand this disease and provide more clinical treatment options.