Recombinant human interleukin 5 is a selective activator of human eosinophil function

IL-5 antagonism reverses priming and activation of eosinophils in severe eosinophilic asthma

Eosinophils are key effector cells mediating airway inflammation and exacerbation in patients with severe eosinophilic asthma. They are present in increased numbers and activation states in the airway mucosa and lumen. Interleukin-5 (IL-5) is the key eosinophil growth factor that is thought to play a role in eosinophil priming and activation. However, the mechanism of these effects is still not fully understood. The anti-IL-5 antibody mepolizumab reduces eosinophil counts in the airway modestly but has a large beneficial effect on the frequency of exacerbations of severe eosinophilic asthma, suggesting that reduction in eosinophil priming and activation is of central mechanistic importance. In this study, we used the therapeutic effect of mepolizumab and single-cell ribonucleic acid sequencing to investigate the mechanism of eosinophil priming and activation by IL-5. We demonstrated that IL-5 is a dominant driver of eosinophil priming and plays multifaceted roles in eosinophil function. It enhances eosinophil responses to other stimulators of migration, survival, and activation by activating phosphatidylinositol-3-kinases, extracellular signal-regulated kinases, and p38 mitogen-activated protein kinases signaling pathways. It also enhances the pro-fibrotic roles of eosinophils in airway remodeling via transforming growth factor-β pathway. These findings provide a mechanistic understanding of eosinophil priming in severe eosinophilic asthma and the therapeutic effect of anti-IL-5 approaches in the disease.

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

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

Translating the biology of β common receptor-engaging cytokines into clinical medicine

The family of cytokines that comprises IL-3, IL-5, and GM-CSF was discovered over 30 years ago, and their biological activities and resulting impact in clinical medicine has continued to expand ever since. Originally identified as bone marrow growth factors capable of acting on hemopoietic progenitor cells to induce their proliferation and differentiation into mature blood cells, these cytokines are also recognized as key mediators of inflammation and the pathobiology of diverse immunologic diseases. This increased understanding of the functional repertoire of IL-3, IL-5, and GM-CSF has led to an explosion of interest in modulating their functions for clinical management. Key to the successful clinical translation of this knowledge is the recognition that these cytokines act by engaging distinct dimeric receptors and that they share a common signaling subunit called β-common or βc. The structural determination of how IL-3, IL-5, and GM-CSF interact with their receptors and linking this to their differential biological functions on effector cells has unveiled new paradigms of cell signaling. This knowledge has paved the way for novel mAbs and other molecules as selective or pan inhibitors for use in different clinical settings.

Mepolizumab decreases tissue eosinophils while increasing type-2 cytokines in eosinophilic chronic rhinosinusitis

BACKGROUND

Eosinophilic chronic rhinosinusitis is an often treatment-resistant inflammatory disease mediated by type-2 cytokines, including interleukin (IL)-5. Mepolizumab, a monoclonal antibody drug targeting IL-5, has demonstrated efficacy and safety in inflammatory airway disease, but there is negligible evidence on direct tissue response. The study's aim was to determine the local effect of mepolizumab on inflammatory biomarkers in sinonasal tissue of eosinophilic chronic rhinosinusitis patients.

METHODS

Adult patients with eosinophilic chronic rhinosinusitis received 100mg mepolizumab subcutaneously at four-weekly intervals for 24 weeks in this prospective phase 2 clinical trial. Tissue eosinophil counts, eosinophil degranulation (assessed as submucosal eosinophil peroxidase deposition by immunohistochemistry) and cytokine levels (measured in homogenates by immunoassay) were evaluated in ethmoid sinus tissue biopsies collected at baseline and at weeks 4, 8, 16 and 24.

RESULTS

Twenty patients (47.7 ± 11.7 years, 50% female) were included. Sinonasal tissue eosinophil counts decreased after 24 weeks of treatment with mepolizumab (101.64 ± 93.80 vs 41.74 ± 53.76 cells per 0.1 mm² ; p = .035), eosinophil degranulation remained unchanged (5.79 ± 2.08 vs 6.07 ± 1.20, p = .662), and type-2 cytokine levels increased in sinonasal tissue for IL-5 (10.84 ± 18.65 vs 63.98 ± 50.66, p = .001), IL-4 (4.48 ± 3.77 vs 9.38 ± 7.56, p = .004), IL-13 (4.02 ± 2.57 vs 6.46 ± 3.99, p = .024) and GM-CSF (1.51 ± 1.74 vs 4.50 ± 2.97, p = .001).

CONCLUSION

Mepolizumab reduced eosinophils in sinonasal tissue, demonstrating that antagonism of IL-5 suppresses eosinophil trafficking. With reduced tissue eosinophils, a local type-2 inflammatory feedback loop may occur. The study exposes mechanistic factors which may explain incomplete treatment response.

Transcriptomic analysis of the anti-inflammatory effect of Cordyceps militaris extract on acute gouty arthritis

Background: Gouty arthritis (GA) is a common inflammatory disease that causes pain due to the deposition of monosodium urate (MSU) crystals into joints and surrounding tissues. Anti-inflammatory drugs have significant clinical anti-inflammatory and analgesic effects, but they have many side effects. Cordyceps militaris is an edible and medicinal fungus, and its extract (CME) has good anti-inflammatory and analgesic effects. This study aimed to investigate the anti-inflammatory effect of CME on GA and its underlying mechanism.

Methods: The effect of CME on the expression of related inflammatory factors and histopathological changes in the MSU-induced acute inflammatory gout model in rats was studied by ELISA and HE, and its anti-inflammatory mechanism was analyzed by transcriptome combined with RT-qPCR.

Results: CME significantly improved gait scores and joint swelling in GA rats, and reduced MSU-induced inflammatory cell infiltration. CME inhibited MSU-induced inflammatory responses by reducing the levels of pro-inflammatory factors TNF-α, IL-1β, IL-6, and Caspase-1 and increasing the anti-inflammatory factor IL-10. Transcriptome analysis showed that CME significantly altered inflammation-related cytokine pathways, and identified four major genes involved in regulation of inflammation, CCL7, CSF2RB, LIF, and IL-1β. In addition, RT-qPCR was performed to verify these differential genes.

Conclusion: CME significantly alleviated the inflammatory progression of GA and ameliorated the onset of GA. The underlying mechanism may be related to triggering the cytokine-cytokine receptor interaction signaling pathway to inhibit the activation of the inflammasome and regulate the immune system. And it regulates the inflammatory response induced by MSU crystals through the genes CCL7, CSF2RB, and IL-1β.

Isolation and characterization of eosinophils in bovine blood and small intestine

An effective method to isolate functional eosinophils from blood and tissues is required to analyze the multiple roles eosinophils play in innate immunity and tissue homeostasis. Highspeed cell sorting was used to isolate bovine eosinophils from blood polymorphonuclear (PMN) cells and from small intestine intraepithelial leukocytes. Eosinophils and neutrophils were purified from bovine blood with highspeed cell sorting after gating on autofluorescence (FL1) high and low PMN subpopulations. Highspeed sorting of intestinal eosinophils was accomplished by using a combination of positive (CD45⁺, CD11c^Low, side scatter^High) and negative (CD3^-) selection parameters. Eosinophils sorted from blood PMNs were 88.6 ± 5.8 % (mean + 1 SD; n = 4) pure and yielded significantly (p < 0.05) more RNA than purified neutrophils. Analysis of Toll-like receptor (TLR) gene expression and TLR ligand-induced pro-inflammatory cytokine (IL-1, IL-6, IL-8, and TNFα) gene expression demonstrated significant (p < 0.01) functional differences between blood eosinophils and neutrophils. Eosinophils varied between 14.7 % to 29.3 % of CD45⁺ IELs and purity of sorted intestinal eosinophils was 95 + 3.5 % (mean + 1SD; n = 5). A comparison of mucosal and blood eosinophils revealed significant (p < 0.01) differences in TLR gene expression, supporting the hypothesis that functionally distinct eosinophil populations are present in blood and tissues. In conclusion, highspeed cell sorting provides an effective method to isolate viable eosinophils from blood and tissues that can then be used for transcriptome analyses and in vitro function assays.

The Role of Blood Eosinophils in the Management of COPD: An Attempt to Answer the Important Clinical Questions

Blood eosinophils have been proposed as a surrogate biomarker of airway eosinophilia that can be used for treatment decisions in patients with COPD, mainly for the identification of candidates for the initiation or withdrawal of therapy with inhaled corticosteroids, as well as for the identification of patients at future risk of exacerbations. In this manuscript we review the recent literature on blood eosinophils in the management of patients with COPD, in an attempt to answer the major questions that are relevant for the practicing clinician. A growing body of evidence suggests that eosinophilic COPD may constitute a separate phenotype of the disease with distinct clinical features and blood eosinophils may represent a potential candidate surrogate marker for specific COPD patients. Several points still need to be clarified, including the role of eosinophils for the identification of candidates for future COPD therapies, yet blood eosinophils plausibly represent the most dependable and promising biomarker for the precision management of COPD today.

Systemic hypereosinophilic syndromes: when autoimmunity is Th2 mediated

PURPOSE OF REVIEW

Clinical conditions associated with hypereosinophilia represent a field of particular interest, taking into account the epidemiological impact of the different primary and secondary forms. In addition to a classical Th1 response, also Th2 cells can be involved in the pathogenesis of autoimmune diseases, among them eosinophilic forms such as eosinophilic granulomatosis with polyangiitis.

RECENT FINDINGS

In patients with severe asthma, recent evidence highlights the role of pathogenic autoantibodies against autologous eosinophil proteins (e.g. eosinophil peroxidase) suggest the role of autoimmune mechanisms, particularly in patients in which asthma is included in eosinophilic vasculitis with antineutrophilic autoantibody positivity. Is now evident that in addition to Th2 cells, also type 2 innate lymphoid cells and Th1/Th17 cells play a central role in the pathogenesis of hypereosinophilic syndrome.

SUMMARY

The definition of cellular and molecular mechanisms and the critical role of specific cytokines involved in the pathogenesis of hypereosinophilic syndrome open the way to new therapeutic strategies by using biological agents targeting these specific factors.

A Review of Acquired Autoimmune Blistering Diseases in Inherited Epidermolysis Bullosa: Implications for the Future of Gene Therapy

Gene therapy serves as a promising therapy in the pipeline for treatment of epidermolysis bullosa (EB). However, with great promise, the risk of autoimmunity must be considered. While EB is a group of inherited blistering disorders caused by mutations in various skin proteins, autoimmune blistering diseases (AIBD) have a similar clinical phenotype and are caused by autoantibodies targeting skin antigens. Often, AIBD and EB have the same protein targeted through antibody or mutation, respectively. Moreover, EB patients are also reported to carry anti-skin antibodies of questionable pathogenicity. It has been speculated that activation of autoimmunity is both a consequence and cause of further skin deterioration in EB due to a state of chronic inflammation. Herein, we review the factors that facilitate the initiation of autoimmune and inflammatory responses to help understand the pathogenesis and therapeutic implications of the overlap between EB and AIBD. These may also help explain whether corrections of highly immunogenic portions of protein through gene therapy confers a greater risk towards developing AIBD.

Regulation of Eosinophilia in Asthma-New Therapeutic Approaches for Asthma Treatment

Asthma is a complex and chronic inflammatory disease of the airways, characterized by variable and recurring symptoms, reversible airflow obstruction, bronchospasm, and airway eosinophilia. As the pathophysiology of asthma is becoming clearer, the identification of new valuable drug targets is emerging. IL-5 is one of these such targets because it is the major cytokine supporting eosinophilia and is responsible for terminal differentiation of human eosinophils, regulating eosinophil proliferation, differentiation, maturation, migration, and prevention of cellular apoptosis. Blockade of the IL-5 pathway has been shown to be efficacious for the treatment of eosinophilic asthma. However, several other inflammatory pathways have been shown to support eosinophilia, including IL-13, the alarmin cytokines TSLP and IL-33, and the IL-3/5/GM-CSF axis. These and other alternate pathways leading to airway eosinophilia will be described, and the efficacy of therapeutics that have been developed to block these pathways will be evaluated.

[A preliminary study on the biomarkers of local inflammation in allergic rhinitis]

Objective:This study aimed to explore the biomarkers in nasal secretion that can assist in the diagnosis of allergic rhinitis（AR） and can be used to evaluate the therapeutic effect of AR. Methods:Thirty-three patients with AR and 21 healthy controls were included. The nasal secretion of healthy controls and patients with AR（before and after treatment） were collected. The cytology, the concentrations of cytokines（IL-5, IL-6, IL-8, IL-33, IFN-γ） and inflammatory mediators（ECP, MPO） were detected. Then, we compared the differences of various biomarkers between healthy controls and AR patients（before and after treatment group）. And analyzed the correlation between each biomarkers/biomarkers difference value/the percentage of biomarkers difference value and clinical symptom score/ score difference value / the percentage of score difference value. Results:Compared with normal controls, the levels of ECP, IL-5, IL-6, IL-8, IL-33 and IFN-γ in nasal secretion of AR patients were significantly higher than those of normal controls（P<0.05）. There was no significant difference in MPO. After treatment, ECP decreased significantly（P<0.01）, inflammatory cell grade and eosinophil percentage are also decreased（P<0.01）. However, MPO, IL-5, IL-6, IL-8, IL-33 and IFN-γ did not change significantly. The difference value of ECP before and after treatment was correlated with the difference value of VAS score（r=0.348, P=0.047）. The difference value of IL-5 was correlated with the difference value of VAS score and rhinorrhea, the correlation coefficients were 0.406（P=0.019） and 0.429（P=0.013）, respectively. The difference value of eosinophil percentage in nasal secretion before and after treatment was correlated with nasal congestion, and the correlation coefficient was 0.383. The difference value of eosinophil percentage multiplied by inflammatory cell grade before and after treatment was correlated with VAS score（r=0.417, P=0.016） and nasal congestion difference value（r=0.519, P=0.002）. The percentage of difference value of IFN-γ before and after treatment was correlated with the percentage of difference value of VAS score / rhinorrhea / sneeze / total nasal symptom score. Conclusion:ECP, IL-6, IL-8 and IL-33 in nasal secretion are expected to be objective biomarkers for auxiliary diagnosis of AR. And ECP, IL-5, IFN-γ, eosinophil percentage multiplied by grade is expected to be an objective index to judge the improvement of patients' symptoms after treatment.

Uridine diphosphate-glucose/P2Y14R axis is a nonchemokine pathway that selectively promotes eosinophil accumulation

Allergic asthma is a chronic inflammatory airway disease characterized by dysregulated type 2 immune responses, including degranulating airway eosinophils that induce tissue damage and airway hyperresponsiveness (AHR). The type 2 cytokines interleukin 5 (IL-5) and IL-13 and the eosinophil-specific chemokine CCL11/CCL24/CCL26 axis recruit, activate, and regulate eosinophils in the airways. In this issue of the JCI, Karcz et al. identified a mechanism involving the nucleotide sugar UDP-glucose (UDP-G) and the purinergic receptor P2Y14R in amplifying eosinophil accumulation in the lung. During type 2 inflammation, UDP-G activates P2Y14R on eosinophils, inducing the cells to move and migrate into the lung. Pharmacologically or genetically inhibiting P2Y14R on eosinophils attenuated eosinophil infiltration and AHR. Future experiments, including identifying additional type 2 factors regulating P2Y14R expression on lung eosinophils, are necessary to ascertain the impact of targeting P2Y14R as an alternative or adjunctive therapy to current type 2 biologics for the treatment of asthma.

Biologics or immunotherapeutics for asthma?

Asthma is now recognised as a heterogenous inflammatory disease of the lung based on cellular infiltrates and transcriptional profiles of blood and airway cells. Four distinct subgroups have been defined, eosinophilic (T2), neutrophilic (T1), mixed eosinophilic/neutrophilic and paucigranulocytic. Patients can also be stratified at a molecular level into T2-high, T2-low and/or T1 based on their gene signatures. Current treatments for asthma have been centred on administration of steroids and/or bronchodilators for the relief of bronchoconstriction and inflammation. These treatments are not always effective and often have limited efficacy during exacerbations. Eosinophil expansion and homing to tissues, bronchoconstriction, IgE production and mucus hypersecretion (hallmark features of asthma) are regulated by the type 2 cytokines IL-4, IL-5 and IL-13, the latter of which can induce the expression of the eosinophil chemotactic factors CCL11 and CCL24. A number of new generation biologics (monoclonal antibodies) targeting pathways regulated by the T2 cytokines IL-5 and IL-4/13 (IL-4 receptor alpha) have yielded effective therapies for eosinophil induced exacerbations of severe asthma. Despite these advances, difficulties still remain in treating all exacerbations, and this may reflect the contribution of other inflammatory cells such as neutrophils to pathogenesis. This review describes the effectiveness of targeting T2 pathways, emerging approaches and identifies the potential next steps for therapeutic intervention.

Eosinophil diversity in asthma

Eosinophils are a type of granulated innate immune cells that have long been implicated in a specific type of asthma, referred to as eosinophilic asthma. Several immunotherapeutics that target and deplete eosinophils or limit their numbers are currently widely used and provide improved disease outcome in severe eosinophilic asthma. Current clinical results provide conclusive evidence of a generally detrimental role of eosinophils in asthma. Yet, a small but growing body of reports suggests that eosinophils may be more diverse than currently appreciated. In this review, we explore pre-clinical and clinical evidence that suggests the existence of eosinophil subsets with potentially distinct functional roles in asthma. We conclude by discussing state-of-the-art strategies for deciphering heterogeneity of this complex cell type, and argue this knowledge could translate into the improved personalized treatment of severe eosinophilic asthma.

Anti-inflammatory and immune-regulatory cytokines in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by a failure of spontaneous resolution of inflammation. Although the pro-inflammatory cytokines and mediators that trigger RA have been the focus of intense investigations, the regulatory and anti-inflammatory cytokines responsible for the suppression and resolution of disease in a context-dependent manner have been less well characterized. However, knowledge of the pathways that control the suppression and resolution of inflammation in RA is clinically relevant and conceptually important for understanding the pathophysiology of the disease and for the development of treatments that enable long-term remission. Cytokine-mediated processes such as the activation of T helper 2 cells by IL-4 and IL-13, the resolution of inflammation by IL-9, IL-5-induced eosinophil expansion, IL-33-mediated macrophage polarization, the production of IL-10 by regulatory B cells and IL-27-mediated suppression of lymphoid follicle formation are all involved in governing the regulation and resolution of inflammation in RA. By better understanding these immune-regulatory signalling pathways, new therapeutic strategies for RA can be envisioned that aim to balance and resolve, rather than suppress, inflammation.

Antibody blockade of Dectin-2 suppresses house dust mite-induced Th2 cytokine production in dendritic cell- and monocyte-depleted peripheral blood mononuclear cell co-cultures from asthma patients

Background

Dectin-2, which is a C-type lectin, interacts with the house dust mite (HDM) Dermatophagoides pteronyssinus allergen. This study aimed to investigate whether Dectin-2 blockade by antagonistic monoclonal antibodies (MoAbs) attenuates HDM-induced allergic responses.

Methods

Two anti-Dectin-2 MoAbs were generated and validated for specific binding to Dectin-2 Fc fusion protein (Dectin-2.Fc) and inhibition of Dectin-2.Fc/HDM interaction. Patients with asthma exhibiting high titers of anti-D. pteronyssinus IgE were enrolled. Peripheral blood mononuclear cells with depleted CD14⁺ monocytes were obtained from these patients and co-cultured with autologous monocyte-derived conventional dendritic cells in the presence of D. pteronyssinus or its group 2 allergens (Der p 2). Interleukin (IL)-5 and IL-13 levels in the culture supernatants were determined using ELISA in the presence or absence of anti-Dectin-2 MoAbs.

Results

Two MoAbs, 6A4G7 and 17A1D10, showed specific binding to recombinant Dectin-2.Fc and inhibited HDM binding to Dectin-2.Fc. Both anti-Dectin-2 MoAbs inhibited IL-5 and IL-13 production in co-cultures with Der p 2 stimulation in a dose-dependent manner. 6A4G7 and 17A1D10 (3 μg/mL) significantly inhibited Der p 2-induced (3 μg/mL) IL-5 production by 69.7 and 86.4% and IL-13 production by 84.0 and 81.4%, respectively. Moreover, this inhibitory effect of the two MoAbs remained significant in the presence of D. pteronyssinus.

Conclusions

Anti-Dectin-2 MoAbs significantly inhibited HDM-induced allergic responses in vitro and therefore have the potential to become therapeutic agents in mite-induced allergic diseases.

Bioinformatic analysis of eosinophil activity and its implications for model and target species

Eosinophils are important immune cells that have been implicated in resistance to gastrointestinal nematode (GIN) infections in both naturally and experimentally infected sheep. Proteins of particular importance appear to be IgA-Fc alpha receptor (FcαRI), C-C chemokine receptor type 3 (CCR3), proteoglycan 3 (PRG3, major basic protein 2) and EPX (eosinophil peroxidase). We used known human nucleotide sequences to search the ruminant genomes, followed by translation to protein and sequence alignments to visualize differences between sequences and species. Where a sequence was retrieved for cow, but not for sheep and goat, this was used additionally as a reference sequence. In this review, we show that eosinophil function varies among host species. Consequently, investigations into the mechanisms of ruminant immune responses to GIN should be conducted using the natural host. Specifically, we address differences in protein sequence and structure for eosinophil proteins.

GM-CSF, IL-3, and IL-5 Family of Cytokines: Regulators of Inflammation

The β common chain cytokines GM-CSF, IL-3, and IL-5 regulate varied inflammatory responses that promote the rapid clearance of pathogens but also contribute to pathology in chronic inflammation. Therapeutic interventions manipulating these cytokines are approved for use in some cancers as well as allergic and autoimmune disease, and others show promising early clinical activity. These approaches are based on our understanding of the inflammatory roles of these cytokines; however, GM-CSF also participates in the resolution of inflammation, and IL-3 and IL-5 may also have such properties. Here, we review the functions of the β common cytokines in health and disease. We discuss preclinical and clinical data, highlighting the potential inherent in targeting these cytokine pathways, the limitations, and the important gaps in understanding of the basic biology of this cytokine family.

Dexamethasone Downregulates Expressions of 14-3-3β and γ-Isoforms in Mice with Eosinophilic Meningitis Caused by Angiostrongylus cantonensis Infection

Steroids are commonly used in patients with eosinophilic meningitis caused by A. cantonensis infections. The mechanism steroids act on eosinophilic meningitis remains unclear. In this mouse experiments, expressions of 14-3-3 isoform β and γ proteins significantly increased in the CSF 2–3 weeks after the infection, but not increasedin the dexamethasone-treated group. Expression of 14-3-3 β, γ, ɛ, and θ isoforms increased in brain meninges over the 3-week period after infection and decreased due to dexamethasone treatment. In conclusion, administration of dexamethasone in mice with eosinophilic meningitis decreased expressions of 14-3-3 isoform proteins in the CSF and in brain meninges.

The effect of astragaloside IV on JAK2-STAT6 signalling pathway in mouse model of ovalbumin-induced asthma

Asthma is a chronic inflammatory lung disease of the airway; the incidence and prevalence of asthma remain high worldwide. Astragaloside IV (AS-IV) is the main active constituent of Astragalus membranaceus. Accumulating evidence suggests that AS-IV possesses anti-inflammatory and anti-asthmatic ability, but the potential molecular mechanism is required to further clarify. In this study, the anti-asthmatic effects of AS-IV on mice with ovalbumin (OVA)-induced allergic inflammation were analysed. We analysed airway hyperresponsiveness (AHR), numbers of inflammatory cells, inflammation situation in lung tissue and cytokines level in bronchoalveolar lavage fluid (BALF) between OVA-induced mice with and without AS-IV treatment. Moreover, we explored the possible signalling pathway behind the anti-asthmatic effects. Our results revealed that AS-IV treatment ameliorates airway inflammation and AHR in an OVA-induced asthma model. Besides, AS-IV treatment inhibits the interleukin (IL)-4, -5 and -13 production, and further study indicated that AS-IV treatment downregulates the expression level of p-JAK2/p-STAT6 proteins. Taken together, the present study suggested that the inhibitory effects of AS-IV on asthma therapy are at least partially involved in inhibiting the JAK2/STAT6 signalling pathway.

Codonopsis lanceolata attenuates allergic lung inflammation by inhibiting Th2 cell activation and augmenting mitochondrial ROS dismutase (SOD2) expression

Allergic asthma is a chronic inflammatory disease induced by the inhalation of allergens, which trigger the activation of T helper type 2 (Th2) cells that release Th2 cytokines. Recently, herbal medicines are being considered a major source of novel agents to treat various diseases. In the present study, we evaluated the anti-asthmatic effects of a Codonopsis lanceolata extract (CLE) and the mechanisms involved in its anti-inflammatory effects. Treatment with CLE reduced infiltration of inflammatory cells, especially eosinophils, and the production of mucus in lung tissues. Levels of Th2 cytokines, such as IL-4, IL-5, and IL-13, and chemokines were also decreased following treatment with CLE. Moreover, Th2 cell proportion in vivo and differentiation in vitro were reduced as evidenced by the decreased expression of GATA3⁺. Furthermore, the expression of superoxide dismutase (SOD)2, a mitochondrial ROS (mROS) scavenger, was increased, which was related to Th2 cell regulation. Interestingly, treatment with CLE increased the number of macrophages in the lungs and enhanced the immune-suppressive property of macrophages. Our findings indicate that CLE has potential as a novel therapeutic agent to inhibit Th2 cell differentiation by regulating mROS scavenging.

An update on immune dysregulation in obesity-related insulin resistance

Obesity is associated with chronic low-grade inflammation of the adipose tissue (AT) that might develop into systemic inflammation, insulin resistance (IR) and an increased risk of type 2 diabetes mellitus (T2DM) in severe obese rodents and humans. In the lean state, small normal adipocytes and AT macrophages interact with each other to maintain metabolic homeostasis but during obesity, enlarged adipocytes secrete inflammatory mediators and express immune receptors to recruit immune cells and aggravate the inflammation. The better understanding of the obesity-related inflammatory milieu and the sequential events leading to IR could be helpful in designing new preventive and therapeutic strategies. The present review will discuss the cellular and molecular abnormalities participating in the pathogenesis of obesity in obese individuals as well as high-fat diet (HFD)-fed mice, a mouse model of obesity.

Japanese Cedar Pollen-Specific IgA in Nasal Secretions and Nasal Allergy Symptoms

OBJECTIVE:

IgA-dependent degranulation of eosinophils and positive correlation between IgA and eosinophil cytotoxic protein levels in nasal secretions have been reported. However, the association between IgA and allergic reactions remains unclear. Therefore, we evaluated the changes in Japanese cedar-specific IgA levels and allergy symptoms after Japanese cedar pollen scattering in symptomatic and asymptomatic individuals sensitized to Japanese cedar pollen.

METHODS:

Nasal secretion and serum samples were collected from 31 participants (21 symptomatic and 10 asymptomatic participants) in January (preseason) and March (peak season). Japanese cedar-specific IgA or IgE levels were measured using ELISA with diamond-like carbon-coated chips.

RESULTS:

The ratio of Japanese cedar pollen-specific IgA to total IgA (rIgA) in the nasal secretions of symptomatic participants increased significantly in March compared with that in January ( P < .01); however, the ratio of specific IgE to total IgE (rIgE) in nasal secretions did not. rIgA in nasal secretions among asymptomatic participants also did not increase during pollen season. rIgA in nasal secretions was significantly correlated with nasal allergic symptoms (r = 0.82; P < .0001) with no significant correlation between rIgE and symptoms.

CONCLUSIONS:

To our knowledge, this is the first study to show an association between nasal symptoms and rIgA in nasal secretions, suggesting that rIgA is useful as an antigen-specific biomarker for allergic rhinitis or pollinosis. Furthermore, rIgA values in nasal secretions do not increase in asymptomatic participants sensitized to Japanese cedar during the pollen season.

Innate Lymphoid Cells (ILCs): Cytokine Hubs Regulating Immunity and Tissue Homeostasis

Innate lymphoid cells (ILCs) have emerged as an expanding family of effector cells particularly enriched in the mucosal barriers. ILCs are promptly activated by stress signals and multiple epithelial- and myeloid-cell-derived cytokines. In response, ILCs rapidly secrete effector cytokines, which allow them to survey and maintain the mucosal integrity. Uncontrolled action of ILCs might contribute to tissue damage, chronic inflammation, metabolic diseases, autoimmunity, and cancer. Here we discuss the recent advances in our understanding of the cytokine network that modulate ILC immune responses: stimulating cytokines, signature cytokines secreted by ILC subsets, autocrine cytokines, and cytokines that induce cell plasticity.

Overlapping Effects of New Monoclonal Antibodies for Severe Asthma

Among the monoclonal antibodies (mAbs) developed for severe asthma treatment, three have already been marketed. Omalizumab was the first, more than 10 years ago; today, mepolizumab and reslizumab are also available in the European Union and the US. Omalizumab blocks free immunoglobulin E (IgE), mepolizumab and reslizumab block an interleukin (IL-5). In the near future, dupilumab and benralizumab are expected to emerge as two new alternatives. Benralizumab blocks the receptor for IL-5 (IL5-Rα) and has a direct cytotoxic effect on eosinophils, and dupilumab blocks the α-unit of the heterodimeric receptor for IL-4 and IL-13 (IL-4Rα); as a result, dupilumab can block both IL-4 and IL-13. The purpose of this manuscript is to present the pathophysiology of some immunological aspects of severe asthma, describe the adaptive and innate immunity arms as well as their interrelations (stressing the subordination of the adaptive arm to the innate arm), outline the pharmacologic effects of these mAbs, clarify the overlapping effects of the different mAbs, and discuss the differences between mAbs based on their target molecules. Based on the data presented, I propose omalizumab for patients with an allergic phenotype regardless of their peripheral eosinophilic count, and anti-IL-5 as an alternative in allergic patients with blood eosinophilia in which omalizumab has failed; anti-IL5 for patients with an eosinophilic phenotype and omalizumab as an alternative in patients in whom anti-IL5 fails and IgE ≥30 IU/mL (compassionate use). Omalizumab is also proposed for patients with severe chronic asthma allergic to seasonal allergens.

OK-432 Acts as Adjuvant to Modulate T Helper 2 Inflammatory Responses in a Murine Model of Asthma

Enhanced type 2 helper T (Th2) cell responses to inhaled harmless allergens are strongly associated with the development of allergic diseases. Antigen formulated with an appropriate adjuvant can elicit suitable systemic immunity to protect individuals from disease. Although much has been learned about Th1-favored immunomodulation of OK-432, a streptococcal preparation with antineoplastic activity, little is known about its adjuvant effect for allergic diseases. Herein, we demonstrate that OK-432 acts as an adjuvant to favor a systemic Th1 polarization with an elevation in interferon- (IFN-) γ and ovalbumin- (OVA-) immunoglobulin (Ig) G2a. Prior vaccination with OK-432 formulated against OVA attenuated lung eosinophilic inflammation and Th2 cytokine responses that were caused by challenging with OVA through the airway. This vaccination with OK-432 augmented the ratios of IFN-γ/interleukin- (IL-) 4 cytokine and IgG2a/IgG1 antibody compared to the formulation with Th2 adjuvant aluminum hydroxide (Alum) or antigen only. The results obtained in this study lead us to propose a potential novel adjuvant for clinical use such as prophylactic vaccination for pathogens and immunotherapy in atopic diseases.

Immunobiology of Inherited Muscular Dystrophies

The immune response to acute muscle damage is important for normal repair. However, in chronic diseases such as many muscular dystrophies, the immune response can amplify pathology and play a major role in determining disease severity. Muscular dystrophies are inheritable diseases that vary tremendously in severity, but share the progressive loss of muscle mass and function that can be debilitating and lethal. Mutations in diverse genes cause muscular dystrophy, including genes that encode proteins that maintain membrane strength, participate in membrane repair, or are components of the extracellular matrix or the nuclear envelope. In this article, we explore the hypothesis that an important feature of many muscular dystrophies is an immune response adapted to acute, infrequent muscle damage that is misapplied in the context of chronic injury. We discuss the involvement of the immune system in the most common muscular dystrophy, Duchenne muscular dystrophy, and show that the immune system influences muscle death and fibrosis as disease progresses. We then present information on immune cell function in other muscular dystrophies and show that for many muscular dystrophies, release of cytosolic proteins into the extracellular space may provide an initial signal, leading to an immune response that is typically dominated by macrophages, neutrophils, helper T-lymphocytes, and cytotoxic T-lymphocytes. Although those features are similar in many muscular dystrophies, each muscular dystrophy shows distinguishing features in the magnitude and type of inflammatory response. These differences indicate that there are disease-specific immunomodulatory molecules that determine response to muscle cell damage caused by diverse genetic mutations. © 2018 American Physiological Society. Compr Physiol 8:1313-1356, 2018.

Impact of reslizumab on outcomes of severe asthmatic patients: current perspectives

Approximately 5%–10% of asthmatics suffer from severe asthma. New biological treatments represent a great opportunity to reduce asthma burden and to improve asthma patients’ lives. Reslizumab will soon be available in several European countries. This anti-IL-5 IgG4/κ monoclonal antibody, administered intravenously at a dose of 3 mg/kg over 20–50 minutes every 4 weeks, has been shown to be safe and effective in patients with 400 eosinophils/μL or more in their peripheral blood. The clinical effects in reducing asthma exacerbations and in improving the quality of life and lung function are clear, but further research is needed to determine the best biological compound for a specific cluster of patients. Research data have shown that in patients who were expressing other clinical features of eosinophilic inflammation over asthma (rhinosinusitis and nasal polyposis), the clinical benefit of reslizumab was greater. Furthermore, it has also been observed that in patients with unsatisfactory response to mepolizumab, reslizumab is able to significantly improve the clinical and biological parameters. The aim of personalized medicine is to provide the right drug to the right patient at the right dose at the right moment. The biological treatments that were developed to modify specific pathological pathways not only provide us with the tools for the management of asthma patients but also clarify the biological mechanisms involved in its pathogenesis.

Aberrantly expressed lncRNAs identified by microarray analysis in CD4+T cells in asthmatic patients

The aim of the study was to determine the expression profiles of message RNAs and long non-coding RNAs in CD4⁺T cells of asthmatic patients and to explore the clinical value and biological function. Expression profiles in CD4⁺T cells of asthmatic patients and healthy controls were analyzed by microarray. We found 2725 lncRNAs and 3167 mRNAs differentially expressed. The data were validated by quantitative real time polymerase chain reaction, with 3 up-regulated (ENST00000444682, ENST00000566098, ENST00000583179) and 1 down-regulated (ENST00000579468) lncRNAs found. Receiver operating characteristic curve analysis showed the area under the curve was 0.7058, 0.9026, 0.8361, 0.8316, respectively. Spearman correlation analysis showed that ENST00000566098 was positively related with IL-13 and ENST00000579468 was positively related with peak expiratory flow. Bioinformatics analyses were performed to explore the function of lncRNAs. Specific lncRNAs aberrantly expressed in CD4⁺T cells may take part in the development of asthma and may be used as biomarkers for diagnosis.

Modeling TH 2 responses and airway inflammation to understand fundamental mechanisms regulating the pathogenesis of asthma

In this review, we highlight experiments conducted in our laboratories that have elucidated functional roles for CD4⁺ T-helper type-2 lymphocytes (T_H 2 cells), their associated cytokines, and eosinophils in the regulation of hallmark features of allergic asthma. Notably, we consider the complexity of type-2 responses and studies that have explored integrated signaling among classical T_H 2 cytokines (IL-4, IL-5, and IL-13), which together with CCL11 (eotaxin-1) regulate critical aspects of eosinophil recruitment, allergic inflammation, and airway hyper-responsiveness (AHR). Among our most important findings, we have provided evidence that the initiation of T_H 2 responses is regulated by airway epithelial cell-derived factors, including TRAIL and MID1, which promote T_H 2 cell development via STAT6-dependent pathways. Further, we highlight studies demonstrating that microRNAs are key regulators of allergic inflammation and potential targets for anti-inflammatory therapy. On the background of T_H 2 inflammation, we have demonstrated that innate immune cells (notably, airway macrophages) play essential roles in the generation of steroid-resistant inflammation and AHR secondary to allergen- and pathogen-induced exacerbations. Our work clearly indicates that understanding the diversity and spatiotemporal role of the inflammatory response and its interactions with resident airway cells is critical to advancing knowledge on asthma pathogenesis and the development of new therapeutic approaches.

Signs of atopic dermatitis and contact dermatitis affected by distinct H2-haplotype in the NC/Nga genetic background

We recently advocated in favour of naming a novel H2-haplotype consisting of K^d, D/L^dm7, I-A^k and I-E^k in the atopic dermatitis (AD) mouse model NC/Nga as “H-2^nc.” The role of the H2-haplotype in AD development was investigated in H2^b-congenic NC/Nga mice (NC.h2^b/b and NC.h2^b/nc) established by backcrossing. A severe 2,4-dinitrofluorobenzene (DNFB)-induced dermatitis in NC/Nga was alleviated partially in NC.h2^b/nc and significantly in NC.h2^b/b. The AD phenotype was correlated with thymic stromal lymphopoietin (TSLP)-epidermal expression levels and serum levels of total IgE and IL-18/IL-33. Histologically, allergic contact dermatitis (ACD) was accompanied by lymphocytes and plasma cells-infiltrating perivasculitis in NC.h2^b/nc and NC.h2^b/b and clearly differed from AD accompanied by neutrophils, eosinophils and macrophages-infiltrating diffuse suppurative dermatitis in NC/Nga. Interestingly, IFN-γ/IL-17 production from autoreactive CD4⁺ T-cells remarkably increased in DNFB-sensitised NC.h2^b/b but not in NC/Nga. Our findings suggest that AD or ACD may depend on haplotype H-2^nc or H-2^b, respectively, in addition to the NC/Nga genetic background.

Orchestration of epithelial-derived cytokines and innate immune cells in allergic airway inflammation

Allergic asthma, a chronic respiratory disease, is a leading worldwide health problem, which inflames and constricts the airways, leading to breathing difficulty. Many studies have focused on the pathogenesis contributed by the adaptive immune system, including CD4+ T lymphocytes in delayed type hypersensitivity and B cell-produced IgE in anaphylaxis. More recently, a focus on the airway mucosal barrier and the innate immune system has highlighted, in coordination with T and B cells, to initiate and establish disease. This review highlights the impacts of epithelial-derived cytokines and innate immune cells on allergic airway reactions.

Persistent induction of goblet cell differentiation in the airways: Therapeutic approaches

Dysregulated induction of goblet cell differentiation results in excessive production and retention of mucus and is a common feature of several chronic airways diseases. To date, therapeutic strategies to reduce mucus accumulation have focused primarily on altering the properties of the mucus itself, or have aimed to limit the production of mucus-stimulating cytokines. Here we review the current knowledge of key molecular pathways that are dysregulated during persistent goblet cell differentiation and highlights both pre-existing and novel therapeutic strategies to combat this pathology.

Bach2 Controls Homeostasis of Eosinophils by Restricting the Type-2 Helper Function of T Cells

Bach2 is a transcription factor which represses its target genes and plays important roles in the differentiation of B and T lymphoid cells. Bach2-deficient (KO) mice develop severe pulmonary alveolar proteinosis, which is associated with increased numbers of granulocytes and T cells. Bach2 is essential for the regulation of T cells, but its role in the regulation of granulocytes is not clear. Here, we observed increased numbers of eosinophils but not neutrophils in the bone marrow, spleen, peripheral blood, and bronchoalveolar lavage fluids of Bach2 KO mice compared with those of wild-type (WT) mice. Upon co-transplantation of the bone marrow cells from CD45.2 Bach2 KO and CD45.1/CD45.2 double-positive WT mice to irradiated WT CD45.1/CD45.2 mice, the reconstituted numbers of eosinophils were similar between Bach2 KO and WT cells. These results showed that the deficiency of Bach2 in eosinophils did not directly drive the differentiation of eosinophils. To investigate the effect of Bach2 KO CD4⁺ T cells upon eosinophils, we analyzed Rag2/Bach2-double deficient (dKO) mice which lack lymphocytes including CD4⁺ T cells. Rag2/Bach2 dKO mice did not show any increase in the numbers of eosinophils. Importantly, Bach2 KO mice showed an increase of interleukin-5 (Il-5) in the sera compared with WT mice. These results suggest that up-regulated functions of CD4⁺ T cells including secretion of Il-5 resulted in proliferation and/or migration to peripheral tissues of eosinophils in Bach2 KO mice. We propose that Bach2 controls homeostasis of eosinophils via restricting the production of Il-5 in CD4⁺ T cells.

The Eosinophil in Health and Disease: from Bench to Bedside and Back

Historically, eosinophils have been considered as end-stage cells involved in host protection against parasitic infection and in the mechanisms of hypersensitivity. However, later studies have shown that this multifunctional cell is also capable of producing immunoregulatory cytokines and soluble mediators and is involved in tissue homeostasis and modulation of innate and adaptive immune responses. In this review, we summarize the biology of eosinophils, including the function and molecular mechanisms of their granule proteins, cell surface markers, mediators, and pathways, and present comprehensive reviews of research updates on the genetics and epigenetics of eosinophils. We describe recent advances in the development of epigenetics of eosinophil-related diseases, especially in asthma. Likewise, recent studies have provided us with a more complete appreciation of how eosinophils contribute to the pathogenesis of various diseases, including hypereosinophilic syndrome (HES). Over the past decades, the definition and criteria of HES have been evolving with the progress of our understanding of the disease and some aspects of this disease still remain controversial. We also review recent updates on the genetic and molecular mechanisms of HES, which have spurred dramatic developments in the clinical strategies of diagnosis and treatment for this heterogeneous group of diseases. The conclusion from this review is that the biology of eosinophils provides significant insights as to their roles in health and disease and, furthermore, demonstrates that a better understanding of eosinophil will accelerate the development of new therapeutic strategies for patients.

Monoclonal antibody therapy for the treatment of asthma and chronic obstructive pulmonary disease with eosinophilic inflammation

Eosinophils have been linked with asthma for more than a century, but their role has been unclear. This review discusses the roles of eosinophils in asthma and chronic obstructive pulmonary disease (COPD) and describes therapeutic antibodies that affect eosinophilia. The aims of pharmacologic treatments for pulmonary conditions are to reduce symptoms, slow decline or improve lung function, and reduce the frequency and severity of exacerbations. Inhaled corticosteroids (ICS) are important in managing symptoms and exacerbations in asthma and COPD. However, control with these agents is often suboptimal, especially for patients with severe disease. Recently, new biologics that target eosinophilic inflammation, used as adjunctive therapy to corticosteroids, have proven beneficial and support a pivotal role for eosinophils in the pathology of asthma. Nucala® (mepolizumab; anti-interleukin [IL]-5) and Cinquair® (reslizumab; anti-IL-5), the second and third biologics approved, respectively, for the treatment of asthma, exemplifies these new treatment options. Emerging evidence suggests that eosinophils may contribute to exacerbations and possibly to lung function decline for a subset of patients with COPD. Here we describe the pharmacology of therapeutic antibodies inhibiting IL-5 or targeting the IL-5 receptor, as well as other cytokines contributing to eosinophilic inflammation. We discuss their roles as adjuncts to conventional therapeutic approaches, especially ICS therapy, when disease is suboptimally controlled. These agents have achieved a place in the therapeutic armamentarium for asthma and COPD and will deepen our understanding of the pathogenic role of eosinophils.

Lung-resident eosinophils represent a distinct regulatory eosinophil subset

Increases in eosinophil numbers are associated with infection and allergic diseases, including asthma, but there is also evidence that eosinophils contribute to homeostatic immune processes. In mice, the normal lung contains resident eosinophils (rEos), but their function has not been characterized. Here, we have reported that steady-state pulmonary rEos are IL-5-independent parenchymal Siglec-FintCD62L+CD101lo cells with a ring-shaped nucleus. During house dust mite-induced airway allergy, rEos features remained unchanged, and rEos were accompanied by recruited inflammatory eosinophils (iEos), which were defined as IL-5-dependent peribronchial Siglec-FhiCD62L-CD101hi cells with a segmented nucleus. Gene expression analyses revealed a more regulatory profile for rEos than for iEos, and correspondingly, mice lacking lung rEos showed an increase in Th2 cell responses to inhaled allergens. Such elevation of Th2 responses was linked to the ability of rEos, but not iEos, to inhibit the maturation, and therefore the pro-Th2 function, of allergen-loaded DCs. Finally, we determined that the parenchymal rEos found in nonasthmatic human lungs (Siglec-8+CD62L+IL-3Rlo cells) were phenotypically distinct from the iEos isolated from the sputa of eosinophilic asthmatic patients (Siglec-8+CD62LloIL-3Rhi cells), suggesting that our findings in mice are relevant to humans. In conclusion, our data define lung rEos as a distinct eosinophil subset with key homeostatic functions.

Mepolizumab for severe refractory eosinophilic asthma: evidence to date and clinical potential

Severe asthma is characterized by major impairment of quality of life, poor symptom control and frequent exacerbations. Inflammatory, clinical and causative factors identify different phenotypes and endotypes of asthma. In the last few years, new treatment options have allowed for targeted treatments according to the different phenotypes of the disease. To accurately select a specific treatment for each asthmatic variant, the identification of appropriate biomarkers is required. Eosinophilic asthma is a distinct phenotype characterized by thickening of the basement membrane and corticosteroid responsiveness. This review reports the latest evidence on an anti-IL-5 monoclonal antibody, mepolizumab, a new and promising biological agent recently approved by the FDA specifically for the treatment of severe eosinophilic refractory asthma.

Protective effect of soybean oil- or fish oil-rich diets on allergic airway inflammation

BACKGROUND

The increased prevalence of asthma and allergic diseases in westernized societies has been associated with increased intake of diets rich in n-6 fatty acids (FAs) and poor in n-3 FAs. This study aimed to analyze the prophylactic effects of treatment with a soybean oil-rich diet (rich in n-6) or fish oil (rich in n-3) in an allergic airway inflammation model on lung inflammation score, leukocyte migration, T-helper cell (Th)-2 (interleukin [IL]-4, IL-5) and Th1 (interferon [IFN]-γ, tumor necrosis factor-α) cytokines, lipoxin A4, nitric oxide, bradykinin, and corticosterone levels in bronchoalveolar lavage (BAL) or lungs.

METHODS

Male Wistar rats fed with soybean oil- or fish oil-rich diet or standard rat chow were sensitized twice with ovalbumin-alumen and challenged twice with ovalbumin aerosol. The BAL and lungs were examined 24 hours later.

RESULTS

Both diets, rich in n-6 or n-3 FAs, impaired the allergic lung inflammation and reduced leukocyte migration, eosinophil and neutrophil percentages, and IL-4/IL-5/bradykinin levels in BAL and/or lungs, as well as increased the nitric oxide levels in BAL. The soybean oil-rich diet additionally increased the levels of lipoxin A4 and corticosterone in the lungs.

CONCLUSION

Data presented demonstrated that the n-6 FA-rich diet had protective effect upon allergic airway inflammation and was as anti-inflammatory as the n-3 FA-rich diet, although through different mechanisms, suggesting that both diets could be considered as complementary therapy or a prophylactic alternative for allergic airway inflammation.

Potential therapeutic targets from genetic and epigenetic approaches for asthma

Asthma is a complex disorder characterised by inflammation of airway and symptoms of wheeze and shortness of breath. Allergic asthma, atopic dermatitis and allergic rhinitis are immunoglobulin E (IgE) related diseases. Current therapies targeting asthma rely on non-specific medication to control airway inflammation and prevent symptoms. Severe asthma remains difficult to treat. Genetic and genomic approaches of asthma and IgE identified many novel loci underling the disease pathophysiology. Recent epigenetic approaches also revealed the insights of DNA methylation and chromatin modification on histones in asthma and IgE. More than 30 microRNAs have been identified to have regulating roles in asthma. Understanding the pathways of the novel genetic loci and epigenetic elements in asthma and IgE will provide new therapeutic means for clinical management of the disease in future.

Characterization of the relationship between dose and blood eosinophil response following subcutaneous administration of mepolizumab

OBJECTIVE

Mepolizumab is a humanized IgG1 monoclonal antibody that blocks human IL-5 from binding to the IL-5 receptor, which is mainly expressed on eosinophils. Eosinophils are key cells in the inflammatory cascade of various diseases, including asthma. This study investigated the pharmacokinetic (PK)/pharmacodynamic (PD) relationship between exposure of mepolizumab subcutaneous (SC) administration and blood eosinophil reduction compared with intravenous (IV) administration in adult subjects with asthma.

METHODS

In this multi-center, randomized, open-label, parallel-group, repeat-dose study, 70 adult subjects received one of four possible treatment regimens: mepolizumab 12.5, 125, or 250 mg SC or 75 mg IV. In addition to analyzing the dose and PK/PD relationship, absolute bioavailability, safety, tolerability, and incidence of anti-mepolizumab antibodies were evaluated.

RESULTS

Blood eosinophil levels decreased in a dose-dependent manner with the lowest (12.5 mg) dose clearly differentiating from the other doses. A non-linear inhibition Imax model based on blood eosinophil levels at week 12 identified that the SC doses providing 50% and 90% of maximal blood eosinophil inhibition were 11 mg (95% confidence interval (CI): 5.19 - 16.85) and 99 mg (95% CI: 47 - 152), respectively. The route of administration did not affect the exposure-response relationship. The estimated mepolizumab SC absolute bioavailability (arm) was 74% (90% CI: 54 - 102%). The safety profile of mepolizumab was favorable.

CONCLUSIONS

A dose-dependent reduction in blood eosinophils across all mepolizumab doses investigated was observed. The subcutaneous absolute bioavailability was 74%. The route of administration did not affect the mepolizumab exposure eosinophil response relationship.

The influence of sensitization on mechanisms of organophosphorus pesticide-induced airway hyperreactivity

We previously demonstrated that antigen sensitization increases vulnerability to airway hyperreactivity induced by the organophosphorus pesticide (OP) parathion. Sensitization also changes the mechanism of parathion-induced airway hyperreactivity to one that is dependent on IL-5. To determine whether this effect can be generalized to other OPs, and to other classes of pesticides, we measured airway responsiveness to vagal stimulation or intravenous acetylcholine in nonsensitized and ovalbumin-sensitized guinea pigs 24 hours after a single subcutaneous injection of the OPs diazinon or chlorpyrifos, or the pyrethroid permethrin. Sensitization exacerbated the effects of chlorpyrifos on bronchoconstriction in response to vagal stimulation or intravenous acetylcholine. Pretreatment with function-blocking IL-5 antibody prevented chlorpyrifos-induced airway hyperreactivity in sensitized, but not in nonsensitized, guinea pigs. In sensitized guinea pigs, blocking IL-5 decreased eosinophil activation, as measured by decreased eosinophil major basic protein in the trachea. In contrast, sensitization did not alter diazinon-induced airway hyperreactivity, and permethrin did not cause airway hyperreactivity in either nonsensitized or sensitized guinea pigs. None of the pesticides affected inflammatory cells in the bronchoalveolar lavage fluid or blood. We have previously shown that three different OPs cause airway hyperreactivity via loss of neuronal M2 muscarinic receptor function. Similar to parathion, but unlike diazinon, the mechanism of chlorpyrifos-induced airway hyperreactivity is changed by sensitization. Thus, OP-induced airway hyperreactivity is dependent on sensitization status and on the OP used, which may influence therapeutic approaches.

Profile of anti-IL-5 mAb mepolizumab in the treatment of severe refractory asthma and hypereosinophilic diseases

Asthma is a complex disorder frequently associated with a poor symptom control, concomitant morbidity, mortality, and significant health care costs due to lack of compliance or inadequate therapeutic options. Interleukin-5 (IL-5) plays a key role in the pathogenesis of eosinophilic disorders, and in the latest years has become a definite target for treatment. Besides asthma, other hypereosinophilic disorders include the hypereosinophilic syndrome, eosinophilic granulomatosis with polyangiitis, sinonasal polyposis, COPD with eosinophilic airway inflammation, allergic rhinitis, atopic dermatitis, eosinophilic esophagitis. The introduction of mepolizumab, a fully humanized monoclonal antibody that binds to IL-5, may represent a useful therapeutic option to control exacerbations and improve asthma-related quality of life in a subgroup of patients with persistent airway eosinophilia and moderate to severe asthma. Several studies carried out in recent years allow, at present, a careful patient selection for appropriate individualized treatment in severe asthma. Further research is anyway needed in order to better understand the pathogenetic mechanisms of asthma and to find new biomarkers. The high costs of biological agents as compared with standard drugs may be largely offset by increased clinical efficacy and good safety profile in selected patients.

Outcomes of rapid corticosteroid tapering in acute eosinophilic pneumonia patients with initial eosinophilia

BACKGROUND AND OBJECTIVE

Studies have shown that patients with acute eosinophilic pneumonia (AEP) and with initial eosinophilia have a milder disease than those with an initial normal peripheral eosinophil count (PEC). We investigated the effect of a rapid corticosteroid tapering strategy in AEP patients with initial eosinophilia.

METHODS

We performed a prospective cohort study in patients with AEP with initial eosinophilia (n = 14) who stopped corticosteroid treatment after achieving clinical stabilization compared with AEP patients with an initial normal PEC (n = 45) who received 2-week treatment with corticosteroid.

RESULTS

In total, 59 AEP patients were identified. The median duration of corticosteroid treatment was 4 days (interquartile ranges (IQR), 3-4) in patients with initial eosinophilia and 14 (IQR, 14-14) days in patients with initial normal PEC. No treatment failure occurred in the group with initial eosinophilia; one treatment failure case occurred in the group with an initially normal PEC. The median time to overall clinical stabilization was 3 days, and time to complete resolution of all symptoms and clinical instabilities from diagnosis was 4 days in AEP patients with initial eosinophilia. Both were significantly shorter than those) in the initially normal PEC group, which were 5 and 7 days respectively (both P < 0.001). Adverse effects were lower in AEP patients with initial eosinophilia, and additional medications to relieve adverse effects were only needed in AEP patients with initially normal PEC.

CONCLUSIONS

Rapid corticosteroid tapering may be an acceptable treatment strategy for managing AEP patients with initial eosinophilia.

ATP drives eosinophil effector responses through P2 purinergic receptors

BACKGROUND

Eosinophils recognize various stimuli, such as cytokines, chemokines, immunoglobulins, complement, and external pathogens, resulting in their accumulation in mucosal tissues and the progression of inflammation. Eosinophils are also involved in innate Th2-type immune responses mediated through endogenous danger signals, including IL-33, uric acid (UA), or ATP, in non-sensitized mice exposed to environmental allergens. However, the mechanism involved in eosinophil responses to these danger signals remains insufficiently understood.

METHODS

We examined migration, adhesion, superoxide production and degranulation of human eosinophils. Isolated eosinophils were incubated with monosodium urate (MSU) crystals and ATPγS, a non-hydrolysable ATP analogue. To determine the involvement of P2 or P2Y2 receptors in eosinophil responses to UA and ATP, eosinophils were preincubated with a pan-P2 receptor inhibitor, oxidized ATP (oATP), or anti-P2Y2 antibody before incubation with MSU crystals or ATPγS.

RESULTS

MSU crystals induced adhesion of eosinophils to recombinant human (rh)-ICAM-1 and induced production of superoxide. oATP abolished eosinophil responses to MSU crystals, suggesting involvement of endogenous ATP and its receptors. Furthermore, exogenous ATP, as ATPγS, induced migration of eosinophils through a model basement membrane, adhesion to rh-ICAM-1, superoxide generation, and degranulation of eosinophil-derived neurotoxin (EDN). oATP and anti-P2Y2 significantly reduced these eosinophil responses.

CONCLUSIONS

ATP serves as an essential mediator of functional responses in human eosinophils. Eosinophil responses to ATP may be implicated in airway inflammation in patients with asthma.