Novel peptide nanoparticle-biased antagonist of CCR3 blocks eosinophil recruitment and airway hyperresponsiveness

Critically-ill COVID-19 susceptibility gene CCR3 shows natural selection in sub-Saharan Africans

The prevalence of COVID-19 critical illness varies across ethnicities, with recent studies suggesting that genetic factors may contribute to this variation. The aim of this study was to investigate natural selection signals of genes associated with critically-ill COVID-19 in sub-Saharan Africans. Severe COVID-19 SNPs were obtained from the HGI website. Selection signals were assessed in 661 sub-Sahara Africans from 1000 Genomes Project using integrated haplotype score (iHS), cross-population extended haplotype homozygosity (XP-EHH), and fixation index (Fst). Allele frequency trajectory analysis of ancient DNA samples were used to validate the existing of selection in sub-Sahara Africans. We also used Mendelian randomization to decipher the correlation between natural selection and critically-ill COVID-19. We identified that CCR3 exhibited significant natural selection signals in sub-Sahara Africans. Within the CCR3 gene, rs17217831-A showed both high iHS (Standardized iHS = 2) and high XP-EHH (Standardized XP-EHH = 2.5) in sub-Sahara Africans. Allele frequency trajectory of CCR3 rs17217831-A revealed natural selection occurring in the recent 1,500 years. Natural selection resulted in increased CCR3 expression in sub-Sahara Africans. Mendelian Randomization provided evidence that increased blood CCR3 expression and eosinophil counts lowered the risk of critically ill COVID-19. Our findings suggest that sub-Saharan Africans are resistant to critically ill COVID-19 due to natural selection and identify CCR3 as a potential novel therapeutic target.

Sphingosine kinase 1-specific inhibitor PF543 reduces goblet cell metaplasia of bronchial epithelium in an acute asthma model

Sphingosine kinase 1 (SPHK1) has been shown to play a key role in the pathogenesis of asthma where SPHK1-generated sphingosine-1-phosphate (S1P) is known to mediate innate and adaptive immunity while promoting mast cell degranulation. Goblet cell metaplasia (GCM) contributes to airway obstruction in asthma and has been demonstrated in animal models. We investigated the role of PF543, a SPHK1-specific inhibitor, in preventing the pathogenesis of GCM using a murine (C57BL/6) model of allergen-induced acute asthma. Treatment with PF543 before triple allergen exposure (DRA: House dust mite, Ragweed pollen, and Aspergillus) reduced inflammation, eosinophilic response, and GCM followed by reduced airway hyperreactivity to intravenous methacholine. Furthermore, DRA exposure was associated with increased expression of SPHK1 in the airway epithelium which was reduced by PF543. DRA-induced reduction of acetylated α-tubulin in airway epithelium was associated with an increased expression of NOTCH2 and SPDEF which was prevented by PF543. In vitro studies using human primary airway epithelial cells showed that inhibition of SPHK1 using PF543 prevented an allergen-induced increase of both NOTCH2 and SPDEF. siRNA silencing of SPHK1 prevented the allergen-induced increase of both NOTCH2 and SPDEF. NOTCH2 silencing was associated with a reduction of SPDEF but not that of SPHK1 upon allergen exposure. Our studies demonstrate that inhibition of SPHK1 protected allergen-challenged airways by preventing GCM and airway hyperreactivity, associated with downregulation of the NOTCH2-SPDEF signaling pathway. This suggests a potential novel link between SPHK1, GCM, and airway remodeling in asthma.NEW & NOTEWORTHY The role of SPHK1-specific inhibitor, PF543, in preventing goblet cell metaplasia (GCM) and airway hyperreactivity (AHR) is established in an allergen-induced mouse model. This protection was associated with the downregulation of NOTCH2-SPDEF signaling pathway, suggesting a novel link between SPHK1, GCM, and AHR.

The airway neuro-immune axis as a therapeutic target in allergic airway diseases

Recent evidence has increasingly underscored the importance of the neuro-immune axis in mediating allergic airway diseases, such as allergic asthma and allergic rhinitis. The intimate spatial relationship between neurons and immune cells suggests that their interactions play a pivotal role in regulating allergic airway inflammation. Upon direct activation by allergens, neurons and immune cells engage in interactions, during which neurotransmitters and neuropeptides released by neurons modulate immune cell activity. Meanwhile, immune cells release inflammatory mediators such as histamine and cytokines, stimulating neurons and amplifying neuropeptide production, thereby exacerbating allergic inflammation. The dynamic interplay between the nervous and immune systems suggests that targeting the neuro-immune axis in the airway could represent a novel approach to treating allergic airway diseases. This review summarized recent evidence on the nervous system's regulatory mechanisms in immune responses and identified potential therapeutic targets along the peripheral nerve-immune axis for allergic asthma and allergic rhinitis. The findings will provide novel perspectives on the management of allergic airway diseases in the future.

IgE directly affects eosinophil migration in chronic rhinosinusitis with nasal polyps through CCR3 and predicts the efficacy of omalizumab

BACKGROUND

Whether IgE affects eosinophil migration in chronic rhinosinusitis with nasal polyps (CRSwNP) remains largely unclear. Moreover, our understanding of local IgE, eosinophils, and omalizumab efficacy in CRSwNP remains limited.

OBJECTIVE

We investigated whether IgE acts directly on eosinophils and determined its role in omalizumab therapy.

METHODS

Eosinophils and their surface receptors were detected by hematoxylin and eosin staining and flow cytometry. IgE and its receptors, eosinophil peroxidase (EPX), eosinophilic cationic protein, and CCR3 were detected by immunohistochemistry and immunofluorescence. Functional analyses were performed on blood eosinophils and polyp tissues. Logistic regression was performed to screen for risk factors. Receiver operating characteristic curve was generated to evaluate the accuracy.

RESULTS

Both FcεRI and CD23 were expressed on eosinophils. The expression of FcεRI and CD23 on eosinophil in nasal polyp tissue was higher than in peripheral blood (both P < .001). IgE and EPX colocalized in CRSwNP. IgE directly promoted eosinophil migration by upregulating CCR3 in CRSwNP but not in healthy controls. Omalizumab and lumiliximab were found to be effective in restraining this migration, indicating CD23 was involved in IgE-induced eosinophil migration. Both IgE+ and EPX+ cells were significantly reduced after omalizumab treatment in those who experienced response (IgE+ cells, P = .001; EPX+ cells, P = .016) but not in those with no response (IgE+ cells, P = .060; EPX+ cells, P = .151). Baseline IgE+ cell levels were higher in those with response compared to those without response (P = .024). The baseline local IgE+ cell count predicted omalizumab efficacy with an accuracy of 0.811.

CONCLUSIONS

IgE directly promotes eosinophil migration, and baseline local IgE+ cell counts are predictive of omalizumab efficacy in CRSwNP.

An update on mechanisms of pruritus and their potential treatment in primary cutaneous T-cell lymphoma

Primary cutaneous T-cell lymphomas (CTCL), which include mycosis fungoides (MF) and Sézary syndrome (SS), are a group of lymphoproliferative disorders characterized by clonal accumulation of neoplastic T-lymphocytes in the skin. Severe pruritus, one of the most common and distressing symptoms in primary CTCL, can significantly impair emotional well-being, physical functioning, and interpersonal relationships, thus greatly reducing quality of life. Unfortunately, effectively managing pruritus remains challenging in CTCL patients as the underlying mechanisms are, as of yet, not fully understood. Previous studies investigating the mechanisms of itch in CTCL have identified several mediators and their corresponding antagonists used for treatment. However, a comprehensive overview of the mediators and receptors contributing to pruritus in primary CTCL is lacking in the current literature. Here, we summarize and review the mediators and receptors that may contribute to pruritus in primary CTCL to explore the mechanisms of CTCL pruritus and identify effective therapeutic targets using the PubMed and Web of Science databases. Studies were included if they described itch mediators and receptors in MF and SS. Overall, the available data suggest that proteases (mainly tryptase), and neuropeptides (particularly Substance P) may be of greatest interest. At the receptor level, cytokine receptors, MRGPRs, and TRP channels are most likely important. Future drug development efforts should concentrate on targeting these mediators and receptors for the treatment of CTCL pruritus.

Mechanistic Insights into Eosinophilic Esophagitis: Therapies Targeting Pathophysiological Mechanisms

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease characterized by eosinophilic infiltration of the esophagus. It arises from a complex interplay of genetic predisposition (susceptibility loci), environmental triggers (allergens and dietary antigens), and a dysregulated immune response, mainly mediated by type 2 T helper cell (Th2)-released cytokines, such as interleukin (IL)-4, IL-5, and IL-13. These cytokines control eosinophil recruitment and activation as well as tissue remodeling, contributing to the characteristic features of EoE. The pathogenesis of EoE includes epithelial barrier dysfunction, mast cell activation, eosinophil degranulation, and fibrosis. Epithelial barrier dysfunction allows allergen penetration and promotes immune cell infiltration, thereby perpetuating the inflammatory response. Mast cells release proinflammatory mediators and promote eosinophil recruitment and the release of cytotoxic proteins and cytokines, causing tissue damage and remodeling. Prolonged inflammation can lead to fibrosis, resulting in long-term complications such as strictures and dysmotility. Current treatment options for EoE are limited and mainly focus on dietary changes, proton-pump inhibitors, and topical corticosteroids. Novel therapies targeting key inflammatory pathways, such as monoclonal antibodies against IL-4, IL-5, and IL-13, are emerging in clinical trials. A deeper understanding of the complex pathogenetic mechanisms behind EoE will contribute to the development of more effective and personalized therapeutic strategies.

Interplay between G protein-coupled receptors and nanotechnology

G protein-coupled receptors (GPCRs), as the largest family of membrane receptors, actively modulate plasma membrane and endosomal signalling. Importantly, GPCRs are naturally nanosized, and spontaneously formed nanoaggregates of GPCRs (natural nano-GPCRs) may enhance GPCR-related signalling and functions. Although GPCRs are the molecular targets of the majority of marketed drugs, the poor pharmacokinetics and physicochemical properties of GPCR ligands greatly limit their clinical applicability. Nanotechnology, as versatile techniques, can encapsulate GPCR ligands to assemble synthetic nano-GPCRs to overcome their obstacles, robustly elevating drug efficacy and safety. Moreover, endosomal delivery of GPCR ligands by nanoparticles can precisely initiate sustained endosomal signal transduction, while nanotechnology has been widely utilized for isolation, diagnosis, and detection of GPCRs. In turn, due to overexpression of GPCRs on the surface of various types of cells, GPCR ligands can endow nanoparticles with active targeting capacity for specific cells via ligand-receptor binding and mediate receptor-dependent endocytosis of nanoparticles. This significantly enhances the potency of nanoparticle delivery systems. Therefore, emerging evidence has revealed the interplay between GPCRs and nanoparticles, although investigations into their relationship have been inadequate. This review aims to summarize the interaction between GPCRs and nanotechnology for understanding their mutual influences and utilizing their interplay for biomedical applications. It will provide a fundamental platform for developing powerful and safe GPCR-targeted drugs and nanoparticle systems. STATEMENT OF SIGNIFICANCE: GPCRs as molecular targets for the majority of marketed drugs are naturally nanosized, and even spontaneously form nano aggregations (nano-GPCRs). Nanotechnology has also been applied to construct synthetic nano-GPCRs or detect GPCRs, while endosomal delivery of GPCR ligands by nanoparticles can magnify endosomal signalling. Meanwhile, molecular engineering of nanoparticles with GPCRs or their ligands can modulate membrane binding and endocytosis, powerfully improving the efficacy of nanoparticle system. However, there are rare summaries on the interaction between GPCRs and nanoparticles. This review will not only provide a versatile platform for utilizing nanoparticles to modulate or detect GPCRs, but also facilitate better understanding of the designated value of GPCRs for molecular engineering of biomaterials with GPCRs in therapeutical application.

Development of tolerance to chemokine receptor antagonists: current paradigms and the need for further investigation

Chemokine G-protein coupled receptors are validated drug targets for many diseases, including cancer, neurological, and inflammatory disorders. Despite much time and effort spent on therapeutic development, very few chemokine receptor antagonists are approved for clinical use. Among potential reasons for the slow progress in developing chemokine receptor inhibitors, antagonist tolerance, a progressive reduction in drug efficacy after repeated administration, is likely to play a key role. The mechanisms leading to antagonist tolerance remain poorly understood. In many cases, antagonist tolerance is accompanied by increased receptor concentration on the cell surface after prolonged exposure to chemokine receptor antagonists. This points to a possible role of altered receptor internalization and presentation on the cell surface, as has been shown for agonist (primarily opioid) tolerance. In addition, examples of antagonist tolerance in the context of other G-protein coupled receptors suggest the involvement of noncanonical signal transduction in opposing the effects of the antagonists. In this review, we summarize the available progress and challenges in therapeutic development of chemokine receptor antagonists, describe the available knowledge about antagonist tolerance, and propose new avenues for future investigation of this important phenomenon. Furthermore, we highlight the modern methodologies that have the potential to reveal novel mechanisms leading to antagonist tolerance and to propel the field forward by advancing the development of potent "tolerance-free" antagonists of chemokine receptors.

Macrophages Orchestrate Airway Inflammation, Remodeling, and Resolution in Asthma

Asthma is a heterogenous chronic inflammatory lung disease with endotypes that manifest different immune system profiles, severity, and responses to current therapies. Regardless of endotype, asthma features increased immune cell infiltration, inflammatory cytokine release, and airway remodeling. Lung macrophages are also heterogenous in that there are separate subsets and, depending on the environment, different effector functions. Lung macrophages are important in recruitment of immune cells such as eosinophils, neutrophils, and monocytes that enhance allergic inflammation and initiate T helper cell responses. Persistent lung remodeling including mucus hypersecretion, increased airway smooth muscle mass, and airway fibrosis contributes to progressive lung function decline that is insensitive to current asthma treatments. Macrophages secrete inflammatory mediators that induce airway inflammation and remodeling. Additionally, lung macrophages are instrumental in protecting against pathogens and play a critical role in resolution of inflammation and return to homeostasis. This review summarizes current literature detailing the roles and existing knowledge gaps for macrophages as key inflammatory orchestrators in asthma pathogenesis. We also raise the idea that modulating inflammatory responses in lung macrophages is important for alleviating asthma.

Biologic Therapies for Asthma and Allergic Disease: Past, Present, and Future

The discovery of the mechanism underlying allergic disease, mouse models of asthma, and bronchoscopy studies provided initial insights into the role of Th2-type cytokines, including interlukin (IL)-4, IL-5 and IL-13, which became the target of monoclonal antibody therapy. Omalizumab, Benralizumab, Mepolizumab, Reslizumab, and Tezepelumab have been approved. These biologicals have been shown to be good alternative therapies to corticosteroids, particularly in severe asthma management, where they can improve the quality of life of many patients. Given the success in asthma, these drugs have been used in other diseases with type 2 inflammation, including chronic rhinosinusitis with nasal polyps (CRSwNP), atopic dermatitis, and chronic urticaria. Like the Th2-type cytokines, chemokines have also been the target of novel monoclonal therapies. However, they have not proved successful to date. In this review, targeted therapy is addressed from its inception to future applications in allergic diseases.

Treatment of allergic eosinophilic asthma through engineered IL-5-anchored chimeric antigen receptor T cells

Severe eosinophilic asthma (SEA) is a therapy-resistant respiratory condition with poor clinical control. Treatment efficacy and patient compliance of current therapies remain unsatisfactory. Here, inspired by the remarkable success of chimeric antigen receptor-based cellular adoptive immunotherapies demonstrated for the treatment of a variety of malignant tumors, we engineered a cytokine-anchored chimeric antigen receptor T (CCAR-T) cell system using a chimeric IL-5-CD28-CD3ζ receptor to trigger T-cell-mediated killing of eosinophils that are elevated during severe asthma attacks. IL-5-anchored CCAR-T cells exhibited selective and effective killing capacity in vitro and restricted eosinophil differentiation with apparent protection against allergic airway inflammation in two mouse models of asthma. Notably, a single dose of IL-5-anchored CCAR-T cells resulted in persistent protection against asthma-related conditions over three months, significantly exceeding the typical therapeutic window of current mAb-based treatments in the clinics. This study presents a cell-based treatment strategy for SEA and could set the stage for a new era of precision therapies against a variety of intractable allergic diseases in the future.

Potent CCR3 Receptor Antagonist, SB328437, Suppresses Colonic Eosinophil Chemotaxis and Inflammation in the Winnie Murine Model of Spontaneous Chronic Colitis

Eosinophils and their regulatory molecules have been associated with chronic intestinal inflammation and gastrointestinal dysfunctions; eosinophil accumulation in the gut is prominent in inflammatory bowel disease (IBD). The chemokine receptor CCR3 plays a pivotal role in local and systemic recruitment and activation of eosinophils. In this study, we targeted CCR3-ligand interactions with a potent CCR3 receptor antagonist, SB328437, to alleviate eosinophil-associated immunological responses in the Winnie model of spontaneous chronic colitis. Winnie and C57BL/6 mice were treated with SB328437 or vehicle. Clinical and histopathological parameters of chronic colitis were assessed. Flow cytometry was performed to discern changes in colonic, splenic, circulatory, and bone marrow-derived leukocytes. Changes to the serum levels of eosinophil-associated chemokines and cytokines were measured using BioPlex. Inhibition of CCR3 receptors with SB328437 attenuated disease activity and gross morphological damage to the inflamed intestines and reduced eosinophils and their regulatory molecules in the inflamed colon and circulation. SB328437 had no effect on eosinophils and their progenitor cells in the spleen and bone marrow. This study demonstrates that targeting eosinophils via the CCR3 axis has anti-inflammatory effects in the inflamed intestine, and also contributes to understanding the role of eosinophils as potential end-point targets for IBD treatment.

Molecular insights into ligand recognition and activation of chemokine receptors CCR2 and CCR3

Chemokine receptors are a family of G-protein-coupled receptors with key roles in leukocyte migration and inflammatory responses. Here, we present cryo-electron microscopy structures of two human CC chemokine receptor-G-protein complexes: CCR2 bound to its endogenous ligand CCL2, and CCR3 in the apo state. The structure of the CCL2-CCR2-G-protein complex reveals that CCL2 inserts deeply into the extracellular half of the transmembrane domain, and forms substantial interactions with the receptor through the most N-terminal glutamine. Extensive hydrophobic and polar interactions are present between both two chemokine receptors and the Gα-protein, contributing to the constitutive activity of these receptors. Notably, complemented with functional experiments, the interactions around intracellular loop 2 of the receptors are found to be conserved and play a more critical role in G-protein activation than those around intracellular loop 3. Together, our findings provide structural insights into chemokine recognition and receptor activation, shedding lights on drug design targeting chemokine receptors.

Diagnosis and Management of Pediatric Hypereosinophilic Syndrome

Hypereosinophilic syndrome (HES) is a diverse group of disorders characterized by peripheral blood eosinophilia of 1.5 × 10⁹/L (1,500/μL) or greater with evidence of end-organ damage attributable to eosinophilia and no other cause of the end-organ damage. The HES is rare, especially in children. This review aims to provide best practices in diagnosis and treatment of HES in children, including how to differentiate between primary and secondary causes of hypereosinophilia; how to distinguish the differences in clinical presentation, treatment, and prognosis of HES in children and adults; and how to identify key steps in the evaluation and management of HES in children.

Establishment of Novel Anti-Mouse CCR3 Monoclonal Antibodies (C3Mab-6 and C3Mab-7) by N-terminal Peptide Immunization

The CC chemokine receptor 3 (CCR3) is a member of the G protein-coupled receptor family that is highly expressed in eosinophils and basophils. CCR3 has been proposed as a therapeutic target for human immunodeficiency virus and allergy diagnosis. Therefore, in this study, we developed specific and sensitive monoclonal antibodies (mAbs) for mouse CCR3 (mCCR3), which are useful for flow cytometry by peptide immunization. The established anti-mCCR3 mAbs, C₃Mab-6 (rat IgG₁, kappa) and C₃Mab-7 (rat IgG₁, kappa), reacted with mCCR3-overexpressed Chinese hamster ovary-K1 (CHO/mCCR3), in addition to mCCR3-endogenously expressed cell lines, such as P388 (mouse lymphoid neoplasma) and J774-1 (mouse macrophage-like) through flow cytometry. Kinetic analyses using flow cytometry indicated that the dissociation constants (K_Ds) of C₃Mab-6 for CHO/mCCR3, P388, and J774-1 cells were 8.7 × 10^-9 M, 1.4 × 10^-7 M, and 1.7 × 10^-7 M, respectively, whereas the K_Ds of C₃Mab-7 for these cell lines were 3.7 × 10^-9 M, 5.1 × 10^-7 M, and 3.1 × 10^-7 M, respectively. Results also indicated that C₃Mab-6 and C₃Mab-7 are useful for detecting cells expressing CCR3 through flow cytometry, thereby making them potentially beneficial for treating CCR3-expressing cells.

C3Mab-3: A Monoclonal Antibody for Mouse CC Chemokine Receptor 3 for Flow Cytometry

CC chemokine receptor 3 (CCR3) belongs to the G protein-coupled receptor family and is highly expressed in eosinophils and basophils. CCR3 is essential for recruiting eosinophils into the lung. Moreover, CCR3 was found in the serum of colorectal cancer patients higher than in the control group. Therefore, CCR3 will be a useful target for asthma and colorectal cancer diagnosis. This study developed a specific and sensitive monoclonal antibody (mAb) for mouse CCR3 (mCCR3), which is useful for flow cytometry using the Cell-Based Immunization and Screening method. The established anti-mCCR3 mAb, C₃Mab-3 (rat IgG_2a, kappa), reacted with mCCR3-overexpressed Chinese hamster ovary-K1 (CHO/mCCR3) cells through flow cytometry. C₃Mab-3 also reacted with P388 (mouse lymphoid neoplasma) and J774-1 (mouse macrophage-like) cells, which express mCCR3 endogenously. Kinetic analyses using flow cytometry indicated that K_Ds of C₃Mab-3 for CHO/mCCR3, P388, and J774-1 cells were 4.3 × 10^-8 M, 2.6 × 10^-7 M, and 2.4 × 10^-7 M, respectively. C₃Mab-3 could be a valuable tool for elucidating mCCR3-related biological response using flow cytometry.

Pharmacological Strategies and Recent Advancement in Nano-Drug Delivery for Targeting Asthma

With a high prevalence globally, asthma is a severe hazard to human health, as well as an economic and social burden. There are now novel therapies available for asthma with the use of nanotechnology. Recent developments in nanoscience and medicine have encouraged the creation of inhalable nanomedicines that can enhance the efficacy, patient compliance, and life quality for sufferers of asthma. Nanocarriers for asthma therapy, including liposomes, micelles, polymers, dendrimers, and inorganics, are presented in depth in this study as well as the current research status of these nanocarriers. Aerosolized nanomaterial-based drug transport systems are currently being developed, and some examples of these systems, as well as prospective future paths, are discussed. New research subjects include nano-modification of medicines and the development of innovative nano-drugs. Clinical experiments have proven that nanocarriers are both safe and effective. Before nanotherapy can be applied in clinical practice, several obstacles must be addressed. We look at some of the most recent research discoveries in the subject of nanotechnology and asthma therapy in this article.

Gene knockdown of CCR3 reduces eosinophilic inflammation and the Th2 immune response by inhibiting the PI3K/AKT pathway in allergic rhinitis mice

The CCR3 gene plays a critical role in allergic airway inflammation, such as allergic rhinitis (AR), and there is an inflammatory signal link between the nasal cavity and the CCR3 gene in bone marrow. However, the effects of the CCR3 gene in bone marrow cells on AR are not clear. The present study investigated the roles and underlying mechanisms of the bone marrow CCR3 gene in AR mice. Conditional knockout of the bone marrow CCR3 gene (CKO) in mice was generated using the Cre-LoxP recombination system, and offspring genotypes were identified using polymerase chain reaction (PCR). An ovalbumin-induced AR model was established in CKO and wild-type mice to measure eosinophilic inflammation and the Th2 immune response. The following mechanisms were explored using a specific PI3K/AKT pathway inhibitor (Ly294002). We successfully constructed and bred homozygous CKO mice and confirmed a significant increase in CCR3 expression and PI3K/AKT pathway activity in AR mice. Deficiency of the bone marrow CCR3 gene caused a remarkable reduction of CCR3 expression and the PI3K/AKT signaling pathway activity, inhibited histopathological lesions and eosinophil infiltration of the nasal cavity, and reduced the production of Th2 cytokines in serum, which led to the remission of allergic symptoms in AR mice. Ly294002 treatment also decreased these inflammatory indexes in a concentration-dependent manner and blocked inflammatory signals from CCR3, but it did not affect the high expression of CCR3 in AR mice. Collectively, our results suggest that conditional knockout of the bone marrow CCR3 gene can reduce eosinophilic inflammation and the Th2 immune response, which may be due to inhibition of the PI3K/AKT pathway.

CCR3 gene knockout in bone marrow cells ameliorates combined allergic rhinitis and asthma syndrome (CARAS) by reducing airway inflammatory cell infiltration and Th2 cytokines expression in mice model

The present study aims to investigate the effects of CCR3 gene knockout in bone marrow cells (CCR3-KO) on the mouse model of combined allergic rhinitis and asthma syndrome (CARAS). It was found that CCR3-KO significantly reduced eosinophil (EOS) migration into the nasal (NALF) and bronchoalveolar (BALF) cavities of mice, and decreased Th2 cytokines (such as, IL-4, IL-5 and IL-13) levels in nasal mucosa and lung tissues. In addition, histological analysis showed that the damage degree of nasal mucosa structure in ovalbumin (OVA) modulated CCR3-KO mice was significantly less than that in OVA modulated Wild type (WT) mice, with reduced inflammatory cell infiltration and nasal mucus secretion. The infiltration of inflammatory cells in lung tissue was significantly reduced, and the proliferation of lung smooth muscle layer and extracellular matrix (ECM) production were decreased. Symptom analysis showed that CCR3-KO can reduced allergic rhinitis (AR) signals as nose scratching and sneezing. It was also found CCR3-KO reduce OVA-induced weight loss. The results showed that CCR3-KO could reduce the symptoms of allergic inflammation in CARAS mice by reducing airway inflammatory cell infiltration and down-regulating the expression of Th2 cytokines, and CCR3 gene could be used as a target gene for the treatment of CARAS.

Type 2 Inflammation in Eosinophilic Esophagitis: From Pathophysiology to Therapeutic Targets

Eosinophilic esophagitis (EoE) is a chronic immune-mediated disease of the esophagus characterized clinically by symptoms related to esophageal dysfunction and histologically by eosinophil-predominant inflammation, whose incidence is rising. It significantly affects patients’ quality of life and, if left untreated, results in fibrotic complications. Although broad consensus has been achieved on first-line therapy, a subset of patients remains non-responder to standard therapy. The pathogenesis of EoE is multifactorial and results from the complex, still mostly undefined, interaction between genetics and intrinsic factors, environment, and antigenic stimuli. A deep understanding of the pathophysiology of this disease is pivotal for the development of new therapies. This review provides a comprehensive description of the pathophysiology of EoE, starting from major pathogenic mechanisms (genetics, type 2 inflammation, epithelial barrier dysfunction, gastroesophageal reflux, allergens, infections and microbiota) and subsequently focusing on the single protagonists of type 2 inflammation (involved cells, cytokines, soluble effectors, surface proteins and transcription factors) that could represent present and future therapeutic targets, while summarizing previous therapeutic approaches in literature.

Engineered protein nanodrug as an emerging therapeutic tool

Functional proteins are the most versatile macromolecules. They can be obtained by extraction from natural sources or by genetic engineering technologies. The outstanding selectivity, specificity, binding activity, and biocompatibility endow engineered proteins with outstanding performance for disease therapy. Nevertheless, their stability is dramatically impaired in blood circulation, hindering clinical translations. Thus, many strategies have been developed to improve the stability, efficacy, bioavailability, and productivity of therapeutic proteins for clinical applications. In this review, we summarize the recent progress in the fabrication and application of therapeutic proteins. We first introduce various strategies for improving therapeutic efficacy via bioengineering and nanoassembly. Furthermore, we highlight their diverse applications as growth factors, nanovaccines, antibody-based drugs, bioimaging molecules, and cytokine receptor antagonists. Finally, a summary and perspective for the future development of therapeutic proteins are presented.

Regulated on Activation, Normal T cell Expressed and Secreted (RANTES) drives the resolution of allergic asthma

RANTES is implicated in allergic asthma and in T cell-dependent clearance of infection. RANTES receptor family comprises CCR1, CCR3, and CCR5, which are G-protein-coupled receptors consisting of seven transmembrane helices. Infections with respiratory viruses like Rhinovirus cause induction of RANTES production by epithelial cells. Here, we studied the role of RANTES in the peripheral blood mononuclear cells in cohorts of children with and without asthma and validated and extended this study to the airways of adults with and without asthma. We further translated these studies to a murine model of asthma induced by house dust mite allergen in wild-type RANTES and CCR5-deficient mice. Here we show an unpredicted therapeutic role of RANTES in the resolution of allergen-induced asthma by orchestrating the transition of effector GATA-3+CD4+ T cells into immune-regulatory-type T cells and inflammatory eosinophils into resident eosinophils as well as increased IL-10 production in the lung.

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RANTES is associated with allergic asthma and T cell-dependent clearance of infections

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RANTES is upregulated in asthmatic airways reflecting ongoing airway cell activation

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Rhinovirus inhibited and antiviral agonist induced RANTES in PBMCs from asthmatics

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Experimental treatment with RANTES (rRANTES) in the airways reduced local eosinophils

Could the Epigenetics of Eosinophils in Asthma and Allergy Solve Parts of the Puzzle?

Epigenetics is a field of study investigating changes in gene expression that do not alter the DNA sequence. These changes are often influenced by environmental or social factors and are reversible. Epigenetic mechanisms include DNA methylation, histone modification, and noncoding RNA. Understanding the role of these epigenetic mechanisms in human diseases provides useful information with regard to disease severity and development. Several studies have searched for the epigenetic mechanisms that regulate allergies and asthma; however, only few studies have used samples of eosinophil, a proinflammatory cell type known to be largely recruited during allergic or asthmatic inflammation. Such studies would enable us to better understand the factors that influence the massive recruitment of eosinophils during allergic and asthmatic symptoms. In this review, we sought to summarize different studies that aimed to discover differential patterns of histone modifications, DNA methylation, and noncoding RNAs in eosinophil samples of individuals with certain diseases, with a particular focus on those with asthma or allergic diseases.

Increased MMP12 mRNA expression in induced sputum was correlated with airway eosinophilic inflammation in asthma patients: evidence from bioinformatic analysis and experiment verification

BACKGROUND

Asthma is a common chronic airway inflammatory disease worldwide. Studies on gene expression profiles in induced sputum may provide noninvasive diagnostic biomarkers and therapeutic targets for asthma.

OBJECTIVE

To investigate mRNA expression of MMP12 in induced sputum and its relationship with asthma airway eosinophilic inflammation.

METHODS

GSE76262 dataset was analyzed using R software, weighted gene coexpression network analysis (WGCNA), and protein-protein interaction (PPI) network construction. The top ten hub genes were screened with Cytoscape software (version 3.8.4). We then verified the mRNA expression of MMP12 in two other datasets (GSE137268 and GSE74075) via ROC curve estimates and our induced sputum samples using real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). Finally, we explored the correlation between MMP12 with asthmatic eosinophilic-related indicators.

RESULTS

We obtained the top ten hub genes, namely, CCL17, CCL2, CSF1, CCL22, CCR3, CD69, FCGR2B, CD1C, CD1E, and MMP12 via expression profile screening and validation on the GSE76262 dataset. MMP12 was selected as the candidate gene through further validation on GSE137268 and GSE74075 datasets. Finally, we demonstrated that the mRNA expression of MMP12 is significantly upregulated in induced sputum of asthmatic patients (p<0.05) and significantly correlated with eosinophilic-related indicators (p<0.05). These findings indicated that MMP12 can act as a diagnostic biomarker for asthma.

CONCLUSION

Our study successfully identified and demonstrated that MMP12 is a potential diagnostic biomarker for asthma due to its high expression and association with eosinophilic-related indicators. The results of this study can provide novel insights into asthmatic diagnosis and therapy in the future.

Lessons learned from targeting eosinophils in human disease

Eosinophils are a minor subset of the granulocyte lineage distinguished by their unique morphology, phenotype, cytoplasmic contents, and function. Evolutionarily, these are ancient cells whose existence has been conserved within vertebrates for millions of years, suggesting that their contribution to innate immunity and other pathologic and homeostatic responses are important to the host. Knowledge regarding the role of eosinophils in health and disease took a leap forward in 2004 with the creation of mouse strains deficient in eosinophils. This advance was paralleled in humans using pharmacology, namely, with the development of drugs capable of selectively reducing and sometimes even eliminating human eosinophils in those receiving these agents. As a result, a more definitive picture of what eosinophils do, and do not do, is emerging. This review will summarize recent advances in our understanding of the role of eosinophils in human disease by focusing mainly on data from clinical studies with anti-eosinophil therapies, even though the first of such agents, mepolizumab, was only approved in the USA in November 2015. Information regarding both efficacy and safety will be highlighted, and where relevant, intriguing data from animal models will also be mentioned, especially if there are conflicting effects seen in humans.

Development of Anti-Mouse CC Chemokine Receptor 3 Monoclonal Antibodies for Flow Cytometry

CC chemokine receptor 3 (CCR3), also known as CD193, belongs to class A of G protein-coupled receptors and is present in high levels in eosinophils, basophils, and airway epithelial cells. CCR3 is considered the therapeutic target for human immunodeficiency virus (HIV) infections and allergic diseases; therefore, the development of sensitive monoclonal antibodies (mAbs) for CCR3 has been desired. This study aimed to establish a specific and sensitive mAb against mouse CCR3 (mCCR3) useful for flow cytometry analysis by employing the Cell-Based Immunization and Screening (CBIS) method. The generated anti-mCCR3 mAb, C₃Mab-2 (rat IgG_2b, kappa), was found to react with mCCR3-overexpressed Chinese hamster ovary-K1 (CHO/mCCR3) cells, according to flow cytometric analysis. Also, it reacted with P388 (mouse lymphoid neoplasm) or J774-1 (mouse macrophage-like) cells, which express endogenous mCCR3. Taken together, C₃Mab-2, generated by the CBIS method, can be a valuable tool for detecting mCCR3 on the surface of mouse cells.

Basophils Orchestrating Eosinophils' Chemotaxis and Function in Allergic Inflammation

Eosinophils are well known to contribute significantly to Th2 immunity, such as allergic inflammations. Although basophils have often not been considered in the pathogenicity of allergic dermatitis and asthma, their role in Th2 immunity has become apparent in recent years. Eosinophils and basophils are present at sites of allergic inflammations. It is therefore reasonable to speculate that these two types of granulocytes interact in vivo. In various experimental allergy models, basophils and eosinophils appear to be closely linked by directly or indirectly influencing each other since they are responsive to similar cytokines and chemokines. Indeed, basophils are shown to be the gatekeepers that are capable of regulating eosinophil entry into inflammatory tissue sites through activation-induced interactions with endothelium. However, the direct evidence that eosinophils and basophils interact is still rarely described. Nevertheless, new findings on the regulation and function of eosinophils and basophils biology reported in the last 25 years have shed some light on their potential interaction. This review will focus on the current knowledge that basophils may regulate the biology of eosinophil in atopic dermatitis and allergic asthma.

Parathyroid hormone type 1 receptor regulates osteosarcoma K7M2 Cell growth by interacting with angiotensinogen

This study aimed to determine the interactions between parathyroid hormone type 1 receptor (PTHR1) and angiotensinogen (AGT) and the effects of these agents on osteosarcoma (OS). We constructed a stably transfected mouse OS K7M2 cell line (shPTHR1- K7M2) using shRNA and knocked down AGT in these cells using siRNA-AGT. The transfection efficiency and expression of AGT, chemokine C-C motif receptor 3 (CCR3), and chemokine (C-C motif) ligand 9 (CCL9) were determined using real-time quantitative PCR. Cell viability and colony formation were assessed using Cell Counting Kit-8 and crystal violet staining, respectively. Cell apoptosis and cycle phases were assessed by flow cytometry, and cell migration and invasion were evaluated using Transwell assays. Interference with PTHR1 upregulated the expression of AGT and CCR3, and downregulated that of CCL9, which was further downregulated by AGT knockdown. Cell viability, migration, invasion and colony formation were significantly decreased, while cell apoptosis was significantly increased in shPTHR1-K7M2, compared with those in K7M2 cells (P < .05 for all). However, AGT knockdown further inhibited cell viability after 72 h of culture but promoted cell migration and invasion. PTHR1 interference decreased and increased the numbers of cells in the G0/G1 and G2/M phases, respectively, compared with those in K7M2 cells. Angiotensinogen knockdown increased the number of cells in the G0/G1 phase compared with that in the shPTHR1-K7M2 cells. Therefore, PTHR1 affects cell viability, apoptosis, migration, invasion and colony formation, possibly by regulating AGT/CCL9 in OS cells.

Eosinophil Lineage-Committed Progenitors as a Therapeutic Target for Asthma

Eosinophilic asthma is the most prevalent phenotype of asthma. Although most asthmatics are adequately controlled by corticosteroid therapy, a subset (5-10%) remain uncontrolled with significant therapy-related side effects. This indicates the need for a consideration of alternative treatment strategies that target airway eosinophilia with corticosteroid-sparing benefits. A growing body of evidence shows that a balance between systemic differentiation and local tissue eosinophilopoietic processes driven by traffic and lung homing of bone marrow-derived hemopoietic progenitor cells (HPCs) are important components for the development of airway eosinophilia in asthma. Interleukin (IL)-5 is considered a critical and selective driver of terminal differentiation of eosinophils. Studies targeting IL-5 or IL-5R show that although mature and immature eosinophils are decreased within the airways, there is incomplete ablation, particularly within the bronchial tissue. Eotaxin is a chemoattractant for mature eosinophils and eosinophil-lineage committed progenitor cells (EoP), yet anti-CCR3 studies did not yield meaningful clinical outcomes. Recent studies highlight the role of epithelial cell-derived alarmin cytokines, IL-33 and TSLP, (Thymic stromal lymphopoietin) in progenitor cell traffic and local differentiative processes. This review provides an overview of the role of EoP in asthma and discusses findings from clinical trials with various therapeutic targets. We will show that targeting single mediators downstream of the inflammatory cascade may not fully attenuate tissue eosinophilia due to the multiplicity of factors that can promote tissue eosinophilia. Blocking lung homing and local eosinophilopoiesis through mediators upstream of this cascade may yield greater improvement in clinical outcomes.

Detecting the Multiomics Signatures of Factor-Specific Inflammatory Effects on Airway Smooth Muscles

Smooth muscles are a specific muscle subtype that is widely identified in the tissues of internal passageways. This muscle subtype has the capacity for controlled or regulated contraction and relaxation. Airway smooth muscles are a unique type of smooth muscles that constitute the effective, adjustable, and reactive wall that covers most areas of the entire airway from the trachea to lung tissues. Infection with SARS-CoV-2, which caused the world-wide COVID-19 pandemic, involves airway smooth muscles and their surrounding inflammatory environment. Therefore, airway smooth muscles and related inflammatory factors may play an irreplaceable role in the initiation and progression of several severe diseases. Many previous studies have attempted to reveal the potential relationships between interleukins and airway smooth muscle cells only on the omics level, and the continued existence of numerous false-positive optimal genes/transcripts cannot reflect the actual effective biological mechanisms underlying interleukin-based activation effects on airway smooth muscles. Here, on the basis of newly presented machine learning-based computational approaches, we identified specific regulatory factors and a series of rules that contribute to the activation and stimulation of airway smooth muscles by IL-13, IL-17, or the combination of both interleukins on the epigenetic and/or transcriptional levels. The detected discriminative factors (genes) and rules can contribute to the identification of potential regulatory mechanisms linking airway smooth muscle tissues and inflammatory factors and help reveal specific pathological factors for diseases associated with airway smooth muscle inflammation on multiomics levels.

Design and Generation of Self-Assembling Peptide Virus-like Particles with Intrinsic GPCR Inhibitory Activity

Synthetic analogs of the second transmembrane domain (TM) containing a portion of the extracellular loop 1 of G-protein-coupled receptors (GPCR) can serve as biased antagonists of the corresponding receptor. Analogs with negative charges added to the extracellular end self-assemble into round structures. Addition of polyethylene glycol chains of defined length to the C-terminus of the peptides prevents super aggregation and results in highly uniform particles that can fuse with cell membranes spontaneously. Added PEG chains slow down cell fusion, while attachment of receptor ligands to the surface of particles results in receptor-mediated membrane fusion and cell-selective delivery. Critical assembly concentration of TM peptide particles is in the nanomolar range and thus requires nontraditional methods of determination. In this chapter, we outline sequence selection and design of self-assembling GPCR antagonists, methods of the preparation of the nanoparticles, and biophysical methods of particle characterization. The protocols allow for straightforward rational design, generation, and characterization of self-assembling GPCR antagonists for a variety of applications.

Recent applications and strategies in nanotechnology for lung diseases

Lung diseases, including COVID-19 and lung cancers, is a huge threat to human health. However, for the treatment and diagnosis of various lung diseases, such as pneumonia, asthma, cancer, and pulmonary tuberculosis, are becoming increasingly challenging. Currently, several types of treatments and/or diagnostic methods are used to treat lung diseases; however, the occurrence of adverse reactions to chemotherapy, drug-resistant bacteria, side effects that can be significantly toxic, and poor drug delivery necessitates the development of more promising treatments. Nanotechnology, as an emerging technology, has been extensively studied in medicine. Several studies have shown that nano-delivery systems can significantly enhance the targeting of drug delivery. When compared to traditional delivery methods, several nanoparticle delivery strategies are used to improve the detection methods and drug treatment efficacy. Transporting nanoparticles to the lungs, loading appropriate therapeutic drugs, and the incorporation of intelligent functions to overcome various lung barriers have broad prospects as they can aid in locating target tissues and can enhance the therapeutic effect while minimizing systemic side effects. In addition, as a new and highly contagious respiratory infection disease, COVID-19 is spreading worldwide. However, there is no specific drug for COVID-19. Clinical trials are being conducted in several countries to develop antiviral drugs or vaccines. In recent years, nanotechnology has provided a feasible platform for improving the diagnosis and treatment of diseases, nanotechnology-based strategies may have broad prospects in the diagnosis and treatment of COVID-19. This article reviews the latest developments in nanotechnology drug delivery strategies in the lungs in recent years and studies the clinical application value of nanomedicine in the drug delivery strategy pertaining to the lung.

Biased agonism at chemokine receptors

In the human chemokine system, interactions between the approximately 50 known endogenous chemokine ligands and 20 known chemokine receptors (CKRs) regulate a wide range of cellular functions and biological processes including immune cell activation and homeostasis, development, angiogenesis, and neuromodulation. CKRs are a family of G protein-coupled receptors (GPCR), which represent the most common and versatile class of receptors in the human genome and the targets of approximately one third of all Food and Drug Administration-approved drugs. Chemokines and CKRs bind with significant promiscuity, as most CKRs can be activated by multiple chemokines and most chemokines can activate multiple CKRs. While these ligand-receptor interactions were previously regarded as redundant, it is now appreciated that many chemokine:CKR interactions display biased agonism, the phenomenon in which different ligands binding to the same receptor signal through different pathways with different efficacies, leading to distinct biological effects. Notably, these biased responses can be modulated through changes in ligand, receptor, and or the specific cellular context (system). In this review, we explore the biochemical mechanisms, functional consequences, and therapeutic potential of biased agonism in the chemokine system. An enhanced understanding of biased agonism in the chemokine system may prove transformative in the understanding of the mechanisms and consequences of biased signaling across all GPCR subtypes and aid in the development of biased pharmaceuticals with increased therapeutic efficacy and safer side effect profiles.

Airways exposure of bacterial superantigen SEB enhances bone marrow eosinophil population and facilitates its egress to blood and lung tissue

BACKGROUND

Differentiation of bone marrow eosinophils (BM-EO) and its trafficking to peripheral blood and respiratory mucosa are a hallmark of inflammatory diseases. Staphylococcal enterotoxin B (SEB) has been shown to aggravate airways eosinophilic inflammation. This study aimed to investigate the effects of mouse airways SEB exposure on BM-EO population, as well as its adhesive properties and release of cytokines/chemokines that orchestrate BM-EO trafficking to lungs.

METHODS

Male BALB/c mice were intranasally exposed to SEB (1 μg), and at 4, 16, 24 and 48 h thereafter, bone marrow (BM), circulating blood and bronchoalveolar lavage (BAL) fluid were collected. Levels of cytokines/chemokines and expressions of VLA-4 and CCR3 in BM were evaluated. Adhesion of BM to ICAM-1 and VCAM-1 were also evaluated.

RESULTS

SEB exposure promoted a marked eosinophil influx to BAL at 16 and 24 h after exposure, which was accompanied by significant increases in counts of immature (16 h) and mature (4 to 48 h) forms of eosinophil in BM, along with blood eosinophilia (16 h). In BM, higher levels of eotaxin, IL-5, IL-4, IL-3 and IL-7 were detected at 16 to 48 h. SEB also significantly increased CCR3 expression and calcium levels in BM-EO, and enhanced the cell adhesion to ICAM-1 (24 h) and ICAM-1 (48 h).

CONCLUSION

Airways SEB exposure increases the number of eosinophils in BM by mechanisms involving a network of cytokine and chemokine release, facilitating the BM-EO adhesion to ICAM-1 and VCAM-1 to gain access to the peripheral blood and lung tissues.

Self-assembling Peptides in Current Nanomedicine: Versatile Nanomaterials for Drug Delivery

BACKGROUND

The development of modern nanomedicine greatly depends on the involvement of novel materials as drug delivery system. In order to maximize the therapeutic effects of drugs and minimize their side effects, a number of natural or synthetic materials have been widely investigated for drug delivery. Among these materials, biomimetic self-assembling peptides (SAPs) have received more attention in recent years. Considering the rapidly growing number of SAPs designed for drug delivery, a summary of how SAPs-based drug delivery systems were designed, would be beneficial.

METHOD

We outlined research works on different SAPs that have been investigated as carriers for different drugs, focusing on the design of SAPs nanomaterials and how they were used for drug delivery in different strategies.

RESULTS

Based on the principle rules of chemical complementarity and structural compatibility, SAPs such as ionic self-complementary peptide, peptide amphiphile and surfactant-like peptide could be designed. Determined by the features of peptide materials and the drugs to be delivered, different strategies such as hydrogel embedding, hydrophobic interaction, electrostatic interaction, covalent conjugation or the combination of them could be employed to fabricate SAPs-drug complex, which could achieve slow release, targeted or environment-responsive delivery of drugs. Furthermore, some SAPs could also be combined with other types of materials for drug delivery, or even act as drug by themselves.

CONCLUSION

Various types of SAPs have been designed and used for drug delivery following various strategies, suggesting that SAPs as a category of versatile nanomaterials have promising potential in the field of nanomedicine.

Biased Opioid Antagonists as Modulators of Opioid Dependence: Opportunities to Improve Pain Therapy and Opioid Use Management

Opioid analgesics are effective pain therapeutics but they cause various adverse effects and addiction. For safer pain therapy, biased opioid agonists selectively target distinct μ opioid receptor (MOR) conformations, while the potential of biased opioid antagonists has been neglected. Agonists convert a dormant receptor form (MOR-μ) to a ligand-free active form (MOR-μ*), which mediates MOR signaling. Moreover, MOR-μ converts spontaneously to MOR-μ* (basal signaling). Persistent upregulation of MOR-μ* has been invoked as a hallmark of opioid dependence. Contrasting interactions with both MOR-μ and MOR-μ* can account for distinct pharmacological characteristics of inverse agonists (naltrexone), neutral antagonists (6β-naltrexol), and mixed opioid agonist-antagonists (buprenorphine). Upon binding to MOR-μ*, naltrexone but not 6β-naltrexol suppresses MOR-μ*signaling. Naltrexone blocks opioid analgesia non-competitively at MOR-μ*with high potency, whereas 6β-naltrexol must compete with agonists at MOR-μ, accounting for ~100-fold lower in vivo potency. Buprenorphine's bell-shaped dose-response curve may also result from opposing effects on MOR-μ and MOR-μ*. In contrast, we find that 6β-naltrexol potently prevents dependence, below doses affecting analgesia or causing withdrawal, possibly binding to MOR conformations relevant to opioid dependence. We propose that 6β-naltrexol is a biased opioid antagonist modulating opioid dependence at low doses, opening novel avenues for opioid pain therapy and use management.

Deciphering the role of eosinophils in solid organ transplantation

Eosinophils are rare granulocytes that belong to the innate arm of the immune system. This cell population is traditionally defined as a destructive and cytotoxic mediator in asthma and helminth infection. Limited data in transplantation have suggested that eosinophils play a similar role in potentiating deleterious organ inflammation and immunologic rejection. Contrary to this long-held notion, recent data have uncovered the possibility that eosinophils play an alternative role in immune homeostasis, defense against a wide range of pathogens, as well as downregulation of deleterious inflammation. Specifically, translational data from small animal models of lung transplantation have demonstrated a critical role for eosinophils in the downregulation of alloimmunity. These findings shed new light on the unique immunologic features of the lung allograft and demonstrate that environmental polarization may alter the phenotype and function of leukocyte populations previously thought to be static in nature. In this review, we provide an update on eosinophils in the homeostasis of the lung as well as other solid organs.

Contributions of Eosinophils to Human Health and Disease

The human eosinophil has long been thought to favorably influence innate mucosal immunity but at times has also been incriminated in disease pathophysiology. Research into eosinophil biology has uncovered a number of interesting contributions by eosinophils to health and disease. However, it appears that not all eosinophils from all species are created equal. It remains unclear, for example, exactly how having eosinophils benefits the human host when helminth infections in the developed world have become scarce. This review focuses on our current state of knowledge as it relates to human eosinophils. When information is lacking, we discuss lessons learned from mouse studies that may or may not directly apply to human biology and disease. It is an exciting time to be an "eosinophilosopher" because the use of biologic agents that selectively target eosinophils provides an unprecedented opportunity to define the contribution of this cell to eosinophil-associated human diseases.

Advances in eosinophilic diseases in 2018

Interest in eosinophil biology and eosinophilic diseases is increasing, as reflected in a doubling of the number of annual articles focused on this topic published in the Journal of Allergy and Clinical Immunology over the past decade. Although the majority of these publications relate to eosinophilic asthma, a growing proportion of them focus on breakthroughs in the diagnosis, treatment, and pathogenesis of other eosinophilic disorders, most notably eosinophilic esophagitis. This review highlights advances in our understanding of eosinophilia and eosinophilic disorders (excluding asthma) published in the Journal in 2018.