Intrinsic defect in T cell production of interleukin (IL)-13 in the absence of both IL-5 and eotaxin precludes the development of eosinophilia and airways hyperreactivity in experimental asthma

Molecular Profiling of Inflammatory Mediators in Human Respiratory Syncytial Virus and Human Bocavirus Infection

Infections due to human respiratory syncytial virus (HRSV) and human bocavirus (HBoV) can mediate the release of several pro-inflammatory cytokines such as IL-6, IL-8, and TNF-α, which are usually associated with disease severity in children. In this study, the change in the expression profile of cytokines and chemokines were determined during HRSV, HBoV, and HRSV coinfection with HBoV in 75 nasopharyngeal aspirates (NPAs) samples, positive real-time reverse transcriptase PCR Assay (rRT-PCR) for HRSV (n = 36), HBoV (n = 23) infection alone or HRSV coinfection with HBoV (n = 16). The samples were collected from hospitalized children. qPCR-based detection revealed that the levels of IL-6, IL-8, IL-10, IL-13, IL-33, and G-CSF were significantly (p < 0.05) greater in patients than in controls. IL-4, IL-17, GM-CSF, and CCL-5 were significantly elevated in children with HRSV coinfection with HBoV than in other groups (p < 0.05). TNF-α, IL-6, IL-8, IL-10, IL-13, and IL-33 in children with HRSV were significantly increased in severe infections compared to mild infections. Whereas, IL-10, IL-13, and IL-33 were significantly increased in severe infection in compared a mild infection in children with HBoV. Further large-scale investigations involving isolates are needed to enhance our knowledge of the association between viral infections and cytokine expression patterns during the different stages of HRSV and HBoV infection.

Development of Adaptive Immunity and Its Role in Lung Remodeling

Asthma is characterized by airflow limitations resulting from bronchial closure, which can be either reversible or fixed due to changes in airway tissue composition and structure, also known as remodeling. Airway remodeling is defined as increased presence of mucins-producing epithelial cells, increased thickness of airway smooth muscle cells, angiogenesis, increased number and activation state of fibroblasts, and extracellular matrix (ECM) deposition. Airway inflammation is believed to be the main cause of the development of airway remodeling in asthma. In this chapter, we will review the development of the adaptive immune response and the impact of its mediators and cells on the elements defining airway remodeling in asthma.

Emerging Role of Eosinophils in Resolution of Arthritis

Eosinophils are a minor component of circulating granulocytes, which are classically viewed as end-stage effector cells in host defense against helminth infection and promoting allergic responses. However, a growing body of evidence has emerged showing that eosinophils are versatile leukocytes acting as an orchestrator in the resolution of inflammation. Rheumatoid arthritis (RA) is the most common chronic inflammatory disease characterized by persistent synovitis that hardly resolves spontaneously. Noteworthy, a specific population of eosinophils, that is, regulatory eosinophils (rEos), was identified in the synovium of RA patients, especially in disease remission. Mechanistically, the rEos in the synovium display a unique pro-resolving signature that is distinct from their counterpart in the lung. Herein, we summarize the latest understanding of eosinophils and their emerging role in promoting the resolution of arthritis. This knowledge is crucial to the design of new approaches to rebalancing immune homeostasis in RA, considering that current therapies are centered on inhibiting pro-inflammatory cytokines and mediators rather than fostering the resolution of inflammation.

Molecular allergology approach to allergic asthma

Allergic asthma is a frequently encountered and well described asthma phenotype. However, its precise mechanisms are less known. The tools for targeted selection of patients for an optimal response to intervention (prevention or treatment) are also lacking. Here we explore the potential of the molecular allergology approach to achieve a better understanding of allergic asthma mechanisms, a precise diagnosis and an optimal management of these patients.

Vinpocetine alleviates lung inflammation via macrophage inflammatory protein-1β inhibition in an ovalbumin-induced allergic asthma model

Asthma is a well-known bronchial disease that causes bronchial inflammation, narrowing of the bronchial tubes, and bronchial mucus secretion, leading to bronchial blockade. In this study, we investigated the association between phosphodiesterase (PDE), specifically PDE1, and asthma using 3-isobutyl-1-methylxanthine (IBMX; a non-specific PDE inhibitor) and vinpocetine (Vinp; a PDE1 inhibitor). Balb/c mice were randomized to five treatment groups: control, ovalbumin (OVA), OVA + IBMX, OVA + Vinp, and OVA + dexamethasone (Dex). All mice were sensitized and challenged with OVA, except for the control group. IBMX, Vinp, or Dex was intraperitoneally administered 1 h before the challenge. Vinp treatment significantly inhibited the increase in airway hyper-responsiveness (P<0.001) and reduced the number of inflammatory cells, particularly eosinophils, in the lungs (P<0.01). It also ameliorated the damage to the bronchi and alveoli and decreased the OVA-specific IgE levels in serum, an indicator of allergic inflammation increased by OVA (P<0.05). Furthermore, the increase in interleukin-13, a known Th2 cytokine, was significantly decreased by Vinp (P<0.05), and Vinp regulated the release and mRNA expression of macrophage inflammatory protein-1β (MIP-1β) increased by OVA (P<0.05). Taken together, these results suggest that PDE1 is associated with allergic lung inflammation induced by OVA. Thus, PDE1 inhibitors can be a promising therapeutic target for the treatment of asthma.

Therapeutic effects and mechanisms study of Hanchuan Zupa Granule in a Guinea pig model of cough variant asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Hanchuan Zupa Granule (HCZP), a traditional Chinese ethnodrug, has the functions of supressing a cough, resolving phlegm, warming the lungs, and relieving asthma. In clinical practice employing traditional Chinese medicine (TCM), HCZP is commonly used to treat acute colds, cough and abnormal mucous asthma caused by a cold, or "Nai-Zi-Lai" in the Uygur language. Studies have confirmed the use of HCZP to treat cough variant asthma (CVA) and other respiratory diseases. However, the pharmacological mechanisms of HCZP remain unrevealed.

AIM OF THE STUDY

To investigate the anti-tussive and anti-asthmatic effects and the possible pharmacological mechanisms of HCZP in the treatment of CVA.

MATERIALS AND METHODS

A guinea pig CVA animal model was established by intraperitoneal injection of ovalbumin (OVA) combined with intraperitoneal injection of aluminium hydroxide adjuvant and atomized OVA. Meanwhile, guinea pigs with CVA received oral HCZP (at dosages of 0.571, 0.285 and 0.143 g/kg bodyweight). The number of coughs induced by aerosol capsaicin was recorded, and the airway hyperresponsiveness (AHR) of CVA guinea pigs was detected with the FinePointe series RC system. H&E staining of lung tissues was performed to observe pathological changes. ELISA was used to detect inflammatory cytokines. qRT-PCR and western blotting analyses were used to detect the expression of Th1-specific transcription factor (T-bet), Th2-specific transcription factor (GATA3), and Toll-like receptor 4 (TLR4) signal transduction elements. These methods were performed to assess the protective effects and the potential mechanisms of HCZP on CVA.

RESULTS

Great changes were found in the CVA guinea pig model after HCZP treatment. The number of coughs induced by capsaicin in guinea pigs decreased, the body weights of guinea pigs increased, and inflammation of the eosinophilic airway and AHR were reduced simultaneously. These results indicate that HCZP has a significant protective effect on CVA. A pharmacological study of HCZP showed that the levels of interleukin-4 (IL-4) and IL-5 and tumour necrosis factor-α (TNF-α) in serum decreased. The amount of interferon-γ (IFN-γ) increased, mRNA and protein expression of TLR4 and GATA3 weakened, and mRNA and protein expression of T-bet increased.

CONCLUSIONS

HCZP ameliorated the symptoms of guinea pigs with CVA induced by OVA by regulating the Th1/Th2 imbalance and TLR4 receptors.

Reciprocal Correlations of Inflammatory and Calcium Signaling in Asthma Pathogenesis

Asthma is a chronic disease characterized by airway hyperresponsiveness, which can be caused by exposure to an allergen, spasmogen, or be induced by exercise. Despite its prevalence, the exact mechanisms by which the airway becomes hyperresponsive in asthma are not fully understood. There is evidence that myosin light-chain kinase is overexpressed, with a concomitant downregulation of myosin light-chain phosphatase in the airway smooth muscle, leading to sustained contraction. Additionally, the sarco/endoplasmic reticulum ATPase may be affected by inflammatory cytokines, such as IL-4, IL-5, IL-13, and TNF-α, which are all associated with asthmatic airway inflammation. IL-13 and TNF-α seem to promote sodium/calcium exchanger 1 overexpression as well. Anyhow, the exact mechanisms beyond these dysregulations need to be clarified. Of note, multiple studies show an association between asthma and the ORMLD3 gene, opening new perspectives to future potential gene therapies. Currently, several treatments are available for asthma, although many of them have systemic side effects, or are not effective in patients with severe asthma. Furthering our knowledge on the molecular and pathophysiological mechanisms of asthma plays a pivotal role for the development of new and more targeted treatments for patients who cannot totally benefit from the current therapies.

Modulating Th2 Cell Immunity for the Treatment of Asthma

It is estimated that more than 339 million people worldwide suffer from asthma. The leading cause of asthma development is the breakdown of immune tolerance to inhaled allergens, prompting the immune system's aberrant activation. During the early phase, also known as the sensitization phase, allergen-specific T cells are activated and become central players in orchestrating the subsequent development of allergic asthma following secondary exposure to the same allergens. It is well-established that allergen-specific T helper 2 (Th2) cells play central roles in developing allergic asthma. As such, 80% of children and 60% of adult asthma cases are linked to an unwarranted Th2 cell response against respiratory allergens. Thus, targeting essential components of Th2-type inflammation using neutralizing antibodies against key Th2 modulators has recently become an attractive option for asthmatic patients with moderate to severe symptoms. In addition to directly targeting Th2 mediators, allergen immunotherapy, also known as desensitization, is focused on redirecting the allergen-specific T cells response from a Th2-type profile to a tolerogenic one. This review highlights the current understanding of the heterogeneity of the Th2 cell compartment, their contribution to allergen-induced airway inflammation, and the therapies targeting the Th2 cell pathway in asthma. Further, we discuss available new leads for successful targeting pulmonary Th2 cell responses for future therapeutics.

Korean Red Ginseng affects ovalbumin-induced asthma by modulating IL-12, IL-4, and IL-6 levels and the NF-κB/COX-2 and PGE2 pathways

Background

Asthma is an incurable hyper-responsive disease of the pulmonary system that is caused by various allergens, including indoor and outdoor stimulators. According to the Global Asthma Network, 339 million people suffered from asthma in 2018, with particularly severe forms in children. Numerous treatments for asthma are available; however, they are frequently associated with adverse effects such as growth retardation, neurological disorders (e.g., catatonia, poor concentration, and insomnia), and physiological disorders (e.g., immunosuppression, hypertension, hyperglycemia, and osteoporosis).

Methods

Korean Red Ginseng has long been used to treat numerous diseases in many countries, and we investigated the anti-asthmatic effects and mechanisms of action of Korean Red Ginseng. Eighty-four BALB/c mice were assigned to 6 treatment groups: control, ovalbumin-induced asthma group, dexamethasone treatment group, and 3 groups treated with Korean Red Ginseng water extract (KRGWE) at 5, 25, or 50 mg/kg/day for 5 days. Anti-asthmatic effects of KRGWE were assessed based on biological changes, such as white blood cell counts and differential counts in the bronchoalveolar lavage fluid, serum IgE levels, and histopathological changes in the lungs, and by examining anti-asthmatic mechanisms, such as the cytokines associated with Th1, Th2, and Treg cells and inflammation pathways.

Results

KRGWE affected ovalbumin-induced changes, such as increased white blood cell counts, increased IgE levels, and morphological changes (mucous hypersecretion, epithelial cell hyperplasia, inflammatory cell infiltration) by downregulating cytokines such as IL-12, IL-4, and IL-6 via GATA-3 inactivation and suppression of inflammation via NF-κB/COX-2 and PGE₂ pathways.

Conclusion

KRGWE is a promising drug for asthma treatment.

Mimicking Antigen-Driven Asthma in Rodent Models-How Close Can We Get?

Asthma is a heterogeneous disease with increasing prevalence worldwide characterized by chronic airway inflammation, increased mucus secretion and bronchial hyperresponsiveness. The phenotypic heterogeneity among asthmatic patients is accompanied by different endotypes, mainly Type 2 or non-Type 2. To investigate the pathomechanism of this complex disease many animal models have been developed, each trying to mimic specific aspects of the human disease. Rodents have classically been employed in animal models of asthma. The present review provides an overview of currently used Type 2 vs. non-Type 2 rodent asthma models, both acute and chronic. It further assesses the methods used to simulate disease development and exacerbations as well as to quantify allergic airway inflammation, including lung physiologic, cellular and molecular immunologic responses. Furthermore, the employment of genetically modified animals, which provide an in-depth understanding of the role of a variety of molecules, signaling pathways and receptors implicated in the development of this disease as well as humanized models of allergic inflammation, which have been recently developed to overcome differences between the rodent and human immune systems, are discussed. Nevertheless, differences between mice and humans should be carefully considered and limits of extrapolation should be wisely taken into account when translating experimental results into clinical use.

Socheongryongtang Modulates Asthma-Related Changes via Modulation of TNF-α and T-bet as well as IFN-γ in an Asthma Murine Model

In 2017 the World Health Organization (WHO) reported that 235 million people suffered from asthma, and that 383,000 deaths were due to asthma in 2015. Asthma cannot be completely eradicated and the medications for asthma are associated with many adverse effects. Socheongryongtang is one of the prescriptions which has traditionally been used for the treatment of pulmonary disease, but the anti-asthmatic mechanism is unclear. To investigate the anti-asthmatic mechanism of socheongryongtang, BALB/c mice were divided into five groups: control, asthma-induced control, dexamethasone treatment, and 150 mg/kg or 1500 mg/kg socheongryongtang treatment and several biomarkers were analyzed, such as white blood cell (WBC) and differential counts in broncheoalveolar fluid (BALF), immunoglobulin E (IgE) in serum, and morphological changes/helper T cell-related cytokines/transcription factor in the lung. The therapeutic ingredients were also analyzed. Socheongryongtang inhibited the neutrophils differentiation in BALF, controlled interleukin (IL)-12p40 releasing, down-regulated not only GATA-3 and helper 2 T (Th2) cell transcription factors but also IL-4, and also decreased the level of tumor necrosis factor (TNF)-α in the lung. In addition, through high-performance liquid chromatography (HPLC) analysis, we confirmed that the therapeutic ingredients in socheongryongtang were paeoniflorin, liquiritin, and glycyrrhizin. The oral intake of 7.3 g of socheongryongtang is beneficial for suppressing the possibility of the occurrence of asthma via modulation of TNF-α and T-bet as well as IFN-γ.

Long Noncoding RNAs in the Regulation of Asthma: Current Research and Clinical Implications

Asthma is a chronic airway inflammatory disorder related to variable expiratory airflow limitation, leading to wheeze, shortness of breath, chest tightness, and cough. Its characteristic features include airway inflammation, airway remodeling and airway hyperresponsiveness. The pathogenesis of asthma remains extremely complicated and the detailed mechanisms are not clarified. Long noncoding RNAs (lncRNAs) have been reported to play a prominent role in asthma and function as modulators of various aspects in pathological progress of asthma. Here, we summarize recent advances of lncRNAs in asthma pathogenesis to guide future researches, clinical treatment and drug development, including their regulatory functions in the T helper (Th) 1/Th2 imbalance, Th17/T regulatory (Treg) imbalance, eosinophils dysfunction, macrophage polarization, airway smooth muscle cells proliferation, and glucocorticoid insensitivity.

Distinct functions of eosinophils in severe asthma with type 2 phenotype: clinical implications

Asthma is commonly recognized as a heterogeneous condition with a complex pathophysiology. With advances in the development of multiple medications for patients with asthma, most asthma symptoms are well managed. Nevertheless, 5% to 10% of adult asthmatic patients (called severe asthma) are in uncontrolled or partially controlled status despite intensive treatment. Especially, severe eosinophilic asthma is one of the severe asthma phenotypes characterized by eosinophilia in sputum/blood driven by type 2 immune responses. Eosinophils have been widely accepted as a central effector cell in the lungs. Some evidence has demonstrated that persistent eosinophilia in upper and lower airway mucosa contributes to asthma severity by producing various mediators including cytokines, chemokines and granule proteins. Moreover, extracellular traps released from eosinophils have been revealed to enhance type 2 inflammation in patients with severe asthma. These novel molecules have the ability to induce airway inf lammation and hyperresponsiveness through enhancing innate and type 2 immune responses. In this review, we highlight recent insight into the function of eosinophil extracellular traps in patients with severe asthma. In addition, the role of eosinophil extracellular vesicles in severe asthma is also proposed. Finally, current biologics are suggested as a potential strategy for effective management of severe eosinophilic asthma.

GSTO1-1 is an upstream suppressor of M2 macrophage skewing and HIF-1α-induced eosinophilic airway inflammation

BACKGROUND

Glutathione S-transferases omega class 1 (GSTO1-1) is a unique member of the GST family regulating cellular redox metabolism and innate immunity through the promotion of LPS/TLR4/NLRP3 signalling in macrophages. House dust mite (HDM) triggers asthma by promoting type 2 responses and allergic inflammation via the TLR4 pathway. Although linked to asthma, the role of GSTO1-1 in facilitating type 2 responses and/or HDM-driven allergic inflammation is unknown.

OBJECTIVE

To determine the role of GSTO1-1 in regulating HDM-induced allergic inflammation in a preclinical model of asthma.

METHODS

Wild-type and GSTO1-1-deficient mice were sensitized and aeroallergen challenged with HDM to induce allergic inflammation and subsequently hallmark pathophysiological features characterized.

RESULTS

By contrast to HDM-challenged WT mice, exposed GSTO1-1-deficient mice had increased numbers of eosinophils and macrophages and elevated levels of eotaxin-1 and -2 in their lungs. M1 macrophage-associated factors, such as IL-1β and IL-6, were decreased in GSTO1-1-deficient mice. Conversely, M2 macrophage factors such as Arg-1 and Ym1 were up-regulated. HIF-1α expression was found to be higher in the absence of GSTO1-1 and correlated with the up-regulation of M2 macrophage markers. Furthermore, HIF-1α was shown to bind and activate the eotaxin-2 promotor. Hypoxic conditions induced significant increases in the levels of eotaxin-1 and -2 in GSTO1-deficient BMDMs, providing a potential link between inflammation-induced hypoxia and the regulation of M2 responses in the lung. Collectively, our results suggest that GSTO1-1 deficiency promotes M2-type responses and increased levels of nuclear HIF-1α, which regulates eotaxin (s)-induced eosinophilia and increased disease severity.

CONCLUSION & CLINICAL IMPLICATION

We propose that GSTO1-1 is a novel negative regulator of TLR4-regulated M2 responses acting as an anti-inflammatory pathway. The discovery of a novel HIF-1α-induced eotaxin pathway identifies an unknown connection between hypoxia and the regulation of the severity of allergic inflammation in 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.

Macmoondongtang modulates Th1-/Th2-related cytokines and alleviates asthma in a murine model

Objective

Macmoondongtang has been used as a traditional medicine to treat pulmonary disease in Korea. However, the mechanism underlying its therapeutic effect has yet to be reported. In the present study, the role of macmoondongtang as a respiratory medicine, especially as an anti-asthmatic agent, has been attributed to the down-regulation of interleukin (IL)-4 and tumor necrosis factor (TNF)-α.

Materials & methods

BALB/c mice were divided into five groups: control, asthma-induced control, dexamethasone treatment, treatment with 150 mg/kg macmoondongtang, and treatment with 1500 mg/kg macmoondongtang. To evaluate the anti-asthmatic effect of macmoondongtang, we investigated its suppressive or inhibitory effects against typical asthmatic changes such as differential cell count in bronchioalveolar fluid (BALF), serum IgE levels, lung morphology, expression of Th1/Th2 cell transcription factors such as T-bet and GATA-3, and Th1-/Th2-/Th17-related cytokines such as interferon (IFN)-γ, IL-12p40, IL-4, -5, -13, TNF-α, and IL-6. The active ingredients in macmoondongtang were further analyzed.

Results

Macmoondongtang treatment down-regulated serum IgE level, a very important marker of hyper-responsiveness. It reversed typical morphological changes such as mucous hypersecretion, lung epithelial cell hyperplasia, and inflammatory cell infiltration near bronchioalveolar space and veins. Macmoondongtang significantly decreased neutrophil count in BALF, as well as reduced T-bet, IFN-γ, and TNF-α expression in the lung. It also showed a dose-dependent control of inflammatory cells in BALF, controlled the expression of IL-12, IL-4, and IL-5 genes in the lung, and the protein expression of IL12p40, GATA-3, IL-4, IL-5, and IL-13. The component analysis revealed glycyrrhizin and liquiritin as the active ingredients.

Conclusions

Macmoondongtang treatment alleviates asthma symptoms and modulate the Th1-/Th2- related cytokines. Glycyrrhizin and liquiritin could be the major the active therapeutic components.

Using evasins to target the chemokine network in inflammation

Inflammation, is driven by a network comprising cytokines, chemokines, their target receptors and leukocytes, and is a major pathologic mechanism that adversely affects organ function in diverse human diseases. Despite being supported by substantial target validation, no successful anti-chemokine therapeutic to treat inflammatory disease has yet been developed. This is in part because of the robustness of the chemokine network, which emerges from a large total chemokine load in disease, promiscuous expression of receptors on leukocytes, promiscuous and synergistic interactions between chemokines and receptors, and feedforward loops created by secretion of chemokines by leukocytes themselves. Many parasites, including viruses, helminths and ticks, evade the chemokine network by producing proteins that bind promiscuously to chemokines or their receptors. Evasins - three small glycoproteins identified in the saliva of the brown dog tick - bind multiple chemokines, and are active in several animal models of inflammatory disease. Over 50 evasin homologs have recently been identified from diverse tick species. Characterization of the chemokine binding patterns of evasins show that several have anti-chemokine activities that extend substantially beyond those previously described. These studies indicate that evasins function at the site of the tick bite by reducing total chemokine load. This not only reduces chemokine signaling to receptors, but also interrupts feedforward loops, thus disabling the chemokine network. Taking the lead from nature, a goal for the development of new anti-chemokine therapeutics would be to reduce the total chemokine load in disease. This could be achieved by administering appropriate evasin combinations or by smaller peptides that mimic evasin action.

Anti-asthmatic effects of lepidii seu Descurainiae Semen plant species in ovalbumin-induced asthmatic mice

ETHNOPHARMACOLOGICAL EVIDENCE

Lepidii seu Descurainiae Semen (LDS) is used as a traditional herbal medicine in northeast Asia, mainly in Korea, Japan, and China to treat lung disorders including coughs and phlegm caused by acute and chronic airway inflammation.

AIM OF THE STUDY

Recently, interest regarding health problems incurred by air pollution has rapidly grown. Herbal medicines are being considered as alternative agents to treat various diseases. In the present study, we evaluated and compared the anti-inflammatory effects of LDS, which is derived from Lepidium apetalum Willd. extracts (LAE) and Descurainia sophia (L.) Webb ex Prantl extracts (DSE), on allergic airway inflammation.

MATERIALS AND METHODS

We established an ovalbumin-induced asthmatic mouse model to evaluate the efficacy of LDS extracts. We performed histological examination and measured relevant inflammatory mediators and cells in bronchoalveolar lavage fluid and lung. Furthermore, we conducted an in vitro T helper 2 (Th2) polarization assay, flow cytometry, and western blot analysis.

RESULTS

Asthmatic phenotypes were attenuated by LDS extract treatments. LDS extract administration significantly reduced mucus production, inflammatory cell infiltration into airways, and eosinophil activation. Furthermore, LDS extracts reduced the expression of type 2 cytokines and inhibited differentiation and activation of Th2 cells.

CONCLUSION

LDS alleviated eosinophilic inflammation by inhibiting Th2 cell differentiation, and DSE was more effective in attenuating allergic lung inflammation than LAE.

Severe Eosinophilic Asthma

Asthma is a heterogeneous disease with varying severity. Severe asthma is a subject of constant research because it greatly affects patients’ quality of life, and patients with severe asthma experience symptoms, exacerbations, and medication side effects. Eosinophils, although at first considered insignificant, were later specifically associated with features of the ongoing inflammatory process in asthma, particularly in the severe case. In this review, we discuss new insights into the pathogenesis of severe asthma related to eosinophilic inflammation and the pivotal role of cytokines in a spectrum that is usually referred to as “T2-high inflammation” that accounts for almost half of patients with severe asthma. Recent literature is summarized as to the role of eosinophils in asthmatic inflammation, airway remodeling, and airway hypersensitivity. Major advances in the management of severe asthma occurred the past few years due to the new targeted biological therapies. Novel biologics that are already widely used in severe eosinophilic asthma are discussed, focusing on the choice of the right treatment for the right patient. These monoclonal antibodies primarily led to a significant reduction of asthma exacerbations, as well as improvement of lung function and patient quality of life.

Allium hookeri root extract regulates asthmatic changes through immunological modulation of Th1/Th2‑related factors in an ovalbumin‑induced asthma mouse model

In 2013, WHO estimated that approximately 235 million people suffered from asthma worldwide. Asthma is a hyper responsive disorder, which is related to an imbalance between the T-helper type 1 and 2 cells (henceforth, Th1 and Th2, respectively). Allium hookeri is a plant that is widely used for culinary purposes and also in traditional Asian medicine. The present study was conducted to elucidate the anti-asthmatic effects and mechanism of action of A. hookeri root extracts (AHRE) in an ovalbumin (OVA)-induced asthma mouse model. The mice were divided into five groups, namely, the control, the OVA-treated group, the dexamethasone-treated group, the 30 mg/kg AHRE-treated group, and the 300 mg/kg AHRE-treated group. The total WBC count and the differential cell count in the bronchoalveolar fluid, the level of serum IgE, the histopathological changes in the lung, and changes in the cell surface molecules, the asthma-related cytokine levels, and Th cell transcription factors were evaluated. AHRE significantly ameliorated asthmatic changes, such as the total WBC count, eosinophil count, and the level of IgE; in addition, it reduced mucus hypersecretion, epithelial hyperplasia, and eosinophil infiltration in the lungs. AHRE significantly inhibited the expression of CD68⁺ cells and MHC class II⁺ molecules, Th1 cell transcription factor (T-bet) activation, Th2 cell transcription factor (GATA-3) activation, and TNF-α in the lung tissue. Furthermore, it suppressed cell surface molecules, such as CD4⁺and CD8⁺; Th1-related cytokines, such as IFN-γ and IL-12p40; Th2-related cytokines, such as IL-4 and IL-5; and Th17-related cytokines, such as IL-6 and TNF-α, in a dose-dependent manner. Thus, AHRE may be considered a promising anti-asthmatic drug.

A bispecific antibody strategy to target multiple type 2 cytokines in asthma

BACKGROUND

Asthma is a chronic inflammatory airway disease in which innate and adaptive immune cells act together to cause eosinophilic inflammation, goblet cell metaplasia (GCM), and bronchial hyperreactivity (BHR). In clinical trials using biologicals against IL-4 receptor (IL-4R) α or IL-5, only a subset of patients with moderate-to-severe asthma responded favorably, suggesting that distinct pathophysiologic mechanisms are at play in subgroups of patients called endotypes. However, the effect of multiple cytokine blockade using bispecific antibodies has not been tested.

OBJECTIVE

We sought to target simultaneously the IL-4, IL-13, and IL-5 signaling pathways with a novel IL-4Rα/IL-5-bispecific antibody in a murine house dust mite (HDM) model of asthma.

METHODS

Two mAbs neutralizing IL-4Rα and IL-5 were generated by using a llama-based antibody platform. Their heavy and light chains were then cotransfected in mammalian cells, resulting in a heterogeneous antibody mixture from which the bispecific antibody was isolated by using a dual anti-idiotypic purification process. C57BL/6J mice were finally sensitized and challenged to HDM extracts and treated during challenge with the antibodies.

RESULTS

We successfully generated and characterized the monospecific and bispecific antibodies targeting IL-4Rα and IL-5. The monospecific antibodies could suppress eosinophilia, IgE synthesis, or both, whereas only the IL-4Rα/IL-5-bispecific antibody and the combination of monospecific antibodies additionally inhibited GCM and BHR.

CONCLUSION

Type 2 cytokines act synergistically to cause GCM and BHR in HDM-exposed mice. These preclinical results show the feasibility of generating bispecific antibodies that target multiple cytokine signaling pathways as superior inhibitors of asthma features, including the difficult-to-treat GCM.

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.

Identification of IFN-γ and IL-27 as Critical Regulators of Respiratory Syncytial Virus-Induced Exacerbation of Allergic Airways Disease in a Mouse Model

Respiratory syncytial virus (RSV) infection induces asthma exacerbations, which leads to worsening of clinical symptoms and may result in a sustained decline in lung function. Exacerbations are the main cause of morbidity and mortality associated with asthma, and significantly contribute to asthma-associated healthcare costs. Although glucocorticoids are used to manage exacerbations, some patients respond to them poorly. The underlying mechanisms associated with steroid-resistant exacerbations remain largely unknown. We have previously established a mouse model of RSV-induced exacerbation of allergic airways disease, which mimics hallmark clinical features of asthma. In this study, we have identified key roles for macrophage IFN-γ and IL-27 in the regulation of RSV-induced exacerbation of allergic airways disease. Production of IFN-γ and IL-27 was steroid-resistant, and neutralization of IFN-γ or IL-27 significantly suppressed RSV-induced steroid-resistant airway hyperresponsiveness and airway inflammation. We have previously implicated activation of pulmonary macrophage by TNF-α and/or MCP-1 in the mechanisms of RSV-induced exacerbation. Stimulation of pulmonary macrophages with TNF-α and/or MCP-1 induced expression of both IFN-γ and IL-27. Our findings highlight critical roles for IFN-γ and IL-27, downstream of TNF-α and MCP-1, in the mechanism of RSV-induced exacerbation. Thus, targeting the pathways that these factors activate may be a potential therapeutic approach for virus-induced asthma exacerbations.

Mouse Eosinophils: Identification, Isolation, and Functional Analysis

Eosinophils are bone marrow-derived cells that differentiate in the bone marrow and migrate into the peripheral blood primarily under the regulation of interleukin (IL)-5. Eosinophil levels in the blood are relatively low. However, under steady-state conditions and in settings of allergic inflammation, parasite infections, or even cancer, they migrate and mainly reside in mucosal tissues where they have key effector and immune-modulating functions. Functional studies using eosinophils are not simple, since these cells are terminally differentiated and rapidly die in vitro. Thus, establishing simple methods to characterize, obtain, and functionally assess eosinophil activities is important. In this unit, we describe methodology for identifying tissue eosinophils by flow cytometry. In addition, we provide detailed methods for isolating eosinophils and for differentiating them from bone marrow cells for further functional studies. © 2017 by John Wiley & Sons, Inc.

Opuntia humifusa modulates morphological changes characteristic of asthma via IL-4 and IL-13 in an asthma murine model

Asthma is a chronic pulmonary disease that affects an estimated 235 million people worldwide, but asthma drugs have many adverse effects. Opuntia humifusa (eastern prickly pear) has been used as a food and traditional medicine worldwide; however, its anti-asthmatic effects have not been reported. We evaluated O. humifusa as a potential therapeutic or preventive component of anti-asthmatic drugs. We divided ovalbumin-sensitized mice into the following groups: normal control, asthma-induced control, dexamethasone-treated group (positive control), 50 mg/kg O. humifusa-treated group, 100 mg/kg O. humifusa-treated group, and 500 mg/kg O. humifusa-treated group. Levels of Th1/Th2/Th17-related cytokines were evaluated using RT-PCR, ELISA, and immunohistochemistry. O. humifusa dose-dependently suppressed the morphological changes typically observed in asthma, such as goblet cell hyperplasia, inflammatory cell infiltration, mucous hypersecretion, and relative basement membrane thickening in the respiratory system. These results may be attributable to regulation of Th1-/Th2-/Th17-related factors, especially interleukin (IL)-4 and IL-13. We conclude that O. humifusa is a potential anti-asthmatic functional food.

Abbreviations: O. humifusa: Opuntia humifusa; Th: helper T; RT-PCR: real-time polymerase chain reaction; ELISA: enzyme-linked immunosorbent assay; IL: interleukin; WHO: World Health Organization; IFN-γ: interferon gamma; TNF-α: tumor necrosis factor-alpha; IgE: immunoglobulin E; CD: cluster of differentiation; OVA: ovalbumin; DEX: dexamethasone; BALF: bronchoalveolar fluid; H&E: hematoxylin and eosin; PAS: periodic acid-schiff; PBS: phosphate-buffered saline; BM: basement membrane; cDNA: complementary deoxyribonucleic acid; RNA: ribo nucleic acid; RIPA: radioimmunoprecipitation assay; IHC: immunohistochemistry; HPLC: high-performance liquid chromatography; SD: standard deviation; WBC: white blood cells; APCs: antigen-presenting cells

Newly divided eosinophils limit ozone-induced airway hyperreactivity in nonsensitized guinea pigs

Ozone causes vagally mediated airway hyperreactivity and recruits inflammatory cells, including eosinophils, to lungs, where they mediate ozone-induced hyperreactivity 1 day after exposure but are paradoxically protective 3 days later. We aimed to test the role of newly divided eosinophils in ozone-induced airway hyperreactivity in sensitized and nonsensitized guinea pigs. Nonsensitized and sensitized guinea pigs were treated with 5-bromo-2-deoxyuridine (BrdU) to label newly divided cells and were exposed to air or ozone for 4 h. Later (1 or 3 days later), vagally induced bronchoconstriction was measured, and inflammatory cells were harvested from bone marrow, blood, and bronchoalveolar lavage. Ozone induced eosinophil hematopoiesis. One day after ozone, mature eosinophils dominate the inflammatory response and potentiate vagally induced bronchoconstriction. However, by 3 days, newly divided eosinophils have reached the lungs, where they inhibit ozone-induced airway hyperreactivity because depleting them with antibody to IL-5 or a TNF-α antagonist worsened vagally induced bronchoconstriction. In sensitized guinea pigs, both ozone-induced eosinophil hematopoiesis and subsequent recruitment of newly divided eosinophils to lungs 3 days later failed to occur. Thus mature eosinophils dominated the ozone-induced inflammatory response in sensitized guinea pigs. Depleting these mature eosinophils prevented ozone-induced airway hyperreactivity in sensitized animals. Ozone induces eosinophil hematopoiesis and recruitment to lungs, where 3 days later, newly divided eosinophils attenuate vagally mediated hyperreactivity. Ozone-induced hematopoiesis of beneficial eosinophils is blocked by a TNF-α antagonist or by prior sensitization. In these animals, mature eosinophils are associated with hyperreactivity. Thus interventions targeting eosinophils, although beneficial in atopic individuals, may delay resolution of airway hyperreactivity in nonatopic individuals.

Myeloid Cells in Asthma

Asthma is a heterogeneous chronic inflammatory disorder of the airways, and not surprisingly, many myeloid cells play a crucial role in pathogenesis. Antigen-presenting dendritic cells are the first to recognize the allergens, pollutants, and viruses that are implicated in asthma pathogenesis, and subsequently initiate the adaptive immune response by migrating to lymph nodes. Eosinophils are the hallmark of type 2 inflammation, releasing toxic compounds in the airways and contributing to airway remodeling. Mast cells and basophils control both the early- and late-phase allergic response and contribute to alterations in smooth muscle reactivity. Finally, relatively little is known about neutrophils and macrophages in this disease. Although many of these myeloid cells respond well to treatment with inhaled steroids, there is now an increasing armamentarium of targeted biologicals that can specifically eliminate only one myeloid cell population, like eosinophils. It is only with those new tools that we will be able to fully understand the role of myeloid cells in chronic asthma in humans.

MyD88 modulates eosinophil and neutrophil recruitment as well as IL-17A production during allergic inflammation

The contribution of dysregulated innate immune responses to the pathogenesis of allergic disease remains largely unknown. Herein, we addressed the role of Toll-like receptor signaling in airway inflammation by studying mice rendered deficient for the myeloid differentiation factor 88 (MyD88^-/-) which results in concurrent deficiencies in TLR and IL-1R1 signaling pathways. We show that the lack of MyD88 offers a partial protection from allergic disease evidenced by reduced airway eosinophilia and production of the Th17-associated effector cytokine IL-17A. By contrast, airway hyperreactivity and Th2 cytokine production, the cardinal features of allergic disease, remained unchanged. We found that the impaired IL-17A production in MyD88^-/- mice was associated with defective CD4⁺ T cells, which failed to respond to IL-23 stimulation. The total number of Th17-associated effectors in lymph nodes was likewise decreased. Taken together, our results demonstrate that MyD88-dependent mechanisms are critical for orchestrating lung inflammatory responses, in terms of IL-17A production, as well as eosinophil and neutrophil recruitment.

Eosinophils enhance WNT-5a and TGF-β1 genes expression in airway smooth muscle cells and promote their proliferation by increased extracellular matrix proteins production in asthma

Background

Recent studies have suggested that eosinophils may have a direct effect on airway smooth muscle cells (ASMC), causing their proliferation in patients with asthma, but the precise mechanism of the interaction between these cells remains unknown. We propose that changes in Wnt signaling activity and extracellular matrix (ECM) production may help explain these findings. Therefore, the aim of this study was to investigate the effect of eosinophils from asthmatic and non-asthmatic subjects on Wnt-5a, transforming growth factor β₁ (TGF-β₁), and ECM protein (fibronectin and collagen) gene expression and ASMC proliferation.

Methods

A total of 18 subjects were involved in the study: 8 steroid-free asthma patients and 10 healthy subjects. Peripheral blood eosinophils were isolated using centrifugation and magnetic separation. An individual co-culture of eosinophils with human ASMC was prepared for each study subject. Adhesion of eosinophils to ASMC (evaluated by assaying eosinophil peroxidase activity) was determined following various incubation periods (30, 45, 60, 120, and 240 min). The expression of Wnt-5a, TGF-β₁, and ECM protein genes in ASMC was measured using quantitative real-time polymerase chain reaction (PCR) after 24 h of co-culture. Proliferation of ASMC was measured using the Alamar blue method after 48 h and 72 h of co-culture with eosinophils.

Results

Eosinophils from asthmatic subjects demonstrated increased adhesion to ASMC compared with eosinophils from healthy subjects (p < 0.05) in vitro. The expression of Wnt-5a, TGF-β₁, collagen, and fibronectin genes in ASMC was significantly higher after 24 h of co-culture with eosinophils from asthmatic subjects, while co-culture of ASMC with eosinophils from healthy subjects increased only TGF-β₁ and fibronectin gene expression. ASMC proliferation was augmented after co-culture with eosinophils from asthma patients compared with co-culture with eosinophils from healthy subjects (p < 0.05).

Conclusions

Eosinophils enhance Wnt-5a, TGF-β₁, fibronectin, and collagen gene expression in ASMC and promote proliferation of these cells in asthma.

Trial registration

ClinicalTrials.gov Identifier: NCT02648074.

Erythronium japonicum attenuates histopathological lung abnormalities in a mouse model of ovalbumin-induced asthma

Asthma is a chronic lung condition that can induce mucus hypersecretion and pulmonary obstruction and may even cause death, particularly in children and older individuals. Erythronium japonicum (E. japonicum) is a traditional herb used in Korea and East Asian countries that has been found to exert free radical scavenging activity and anti-proliferative effects in human colorectal carcinoma cells. In the present study, we evaluated the anti-asthmatic effects of an extract of E. japonicum in a mouse model of ovalbumin (OVA)-induced asthma. Female BALB/c mice were sensitized with an intraperitoneal injection of OVA and aluminum hydroxide hydrate on days 1 and 8 and then received the following treatments on days 21 to 25: i) control (no treatment), ii) sterilized tap water (given orally), iii) 1 mg/kg/day dexamethasone (administered orally), iv) 60 mg/kg/day E. japonicum extract, and v) 600 mg/kg/day E. japonicum extract. On the same days, all the mice except those in the control group were challenged 1 h later with nebulized 5% OVA for 30 min. We found that treatment with E. japonicum extract suppressed the OVA-induced increase in the number of white blood cells and decreased the IgE level in the bronchoalveolar lavage fluid samples obtained from the mice. Histopathological analysis of the lung tissues revealed that E. japonicum attenuated the asthma-related morphological changes in the mouse lung tissue, including the increased secretion of mucus in the bronchioles, eosinophil infiltration around the bronchioles and vessels, and goblet cell and epithelial cell hyperplasia. Immunohistochemical analysis revealed that treatment with E. japonicum extract suppressed the OVA-induced proliferation of T helper cells (CD4⁺) and B cells (CD19⁺) in the mouse lung tissue. Furthermore, treatment with E. japonicum extract modulated the expression of both T helper 2 cell-related factors [GATA binding protein 3 (GATA-3), tumor necrosis factor-α (TNF-α), interleukin (IL)-4, IL-5, IL-6 and IL-13], as well as that of T helper 1 cell-related factors [(interferon-γ (IFN-γ), IL-12p35 and IL-12p40]. These findings suggest that E. japonicum may potentially be used as an anti-asthmatic treatment.

Until Death Do Us Part: Necrosis and Oxidation Promote the Tumor Microenvironment

Tumor proliferation is concomitant with autophagy, limited apoptosis, and resultant necrosis. Necrosis is associated with the release of damage-associated molecular pattern molecules (DAMPs), which act as 'danger signals', recruiting inflammatory cells, inducing immune responses, and promoting wound healing. Most of the current treatment strategies for cancer (chemotherapy, radiation therapy, hormonal therapy) promote DAMP release following therapy-induced tumor death by necroptosis and necrosis. Myeloid cells (monocytes, dendritic cells (DCs), and granulocytes), as well as mesenchymal stromal cells (MSCs) belong to the early immigrants in response to unscheduled cell death, initiating and modulating the subsequent inflammatory response. Responding to DAMPs, MSCs, and DCs promote an immunosuppressive milieu, while eosinophils induce oxidative conditions limiting the biologic activity of DAMPs over time and distance. Regulatory T cells are strongly affected by pattern recognition receptor signaling in the tumor microenvironment and limit immune reactivity coordinately with myeloid-derived suppressor cells. Means to 'aerobically' oxidize DAMPs provide a novel strategy for limiting tumor progression. The present article summarizes our current understanding of the impact of necrosis on the tumor microenvironment and the influence of oxidative conditions found within this setting.

Eosinophils

Eosinophils have been traditionally understood as end-stage, primarily cytotoxic effector cells. Recent studies have had profound impact on this limited view and have led to new research on the functions and capabilities of this unique leukocyte lineage. Novel insights into eosinophil development, localization, modes of degranulation, and the nature of their granule contents have provided a better understanding of these cells as immunomodulatory mediators in health and disease.

Eosinophilic Esophagitis and Gastroenteritis

Eosinophilic gastrointestinal disease (EGID) can be classified as eosinophilic esophagitis (EoE) when the eosinophilia is limited to the esophagus or as eosinophilic gastritis (EG) if it is limited to the gastric tract, eosinophilic colitis (EC) if it is limited to the colon, and eosinophilic gastroenteritis (EGE) if the eosinophilia involves one or more parts of the gastrointestinal tract. EoE is by far the most common EGID. It is a well-defined chronic atopic disease due to a T helper type 2 (Th2) inflammation triggered often by food allergens. EoE diagnosis is done if an esophageal biopsy shows at least 15 eosinophils per high power field (eos/hpf). Globally accepted long-term therapies for EoE are the use of swallowed inhaled steroids or food antigen avoidance. The treatment of EoE is done not only to control symptoms but also to prevent complications such as esophageal stricture and food impaction. EGE cause non-specific gastrointestinal (GI) symptoms and are diagnosed if esophagogastroduodenoscopy (EGD)/colonoscopy show eosinophilia in one or more parts of the GI tract. They are rare diseases with an unclear pathogenesis, and they are poorly defined in terms of diagnostic criteria and treatment. Before initiating treatment of any EGE, it is imperative to conduct a differential diagnosis to exclude other causes of hypereosinophilia with GI localization. EGE are often poorly responsive to therapy and there is no commonly accepted long-term treatment. EG has many characteristics similar to EoE, including the fact that it is often due to a food allergen-driven Th2 inflammation; transcriptome analysis however shows that it is more a systemic disease and has a different gene signature than EoE. EC is a benign form of delayed food allergy in infant and is instead a difficult-to-treat severe inflammatory condition in older children and adults. EC in the latter groups can be a manifestation of drug allergy or autoimmune disease. Overall EGE, EC, and EG are rare and are a diagnosis of exclusion until more common causes of eosinophilia have been excluded.

Oxyresveratrol ameliorates allergic airway inflammation via attenuation of IL-4, IL-5, and IL-13 expression levels

AIM

Oxyresveratrol is known to possess anti-inflammatory property. Current study investigates the immunosuppressive effect of oxyresveratrol by using mouse model of ovalbumin (OVA)-induced allergic airway inflammation.

METHODS

BALB/c mice were randomly divided into five groups having 8 mice in each group. Treatment with low dose (7 mg/kg) and high dose (15 mg/kg) of oxyresveratrol, and methylprednisolone (15 mg/kg; standard drug) was started 2 week after immunization of mice with ovalbumin and continued for 7d. Ovalbumin was also injected into pinna of right ear 24h before sacrificing the mice to evaluate delayed type hypersensitivity (DTH). H&E and PAS staining were used for histopathological evaluation of lungs. Reverse transcription polymerase chain reaction followed by gel electrophoresis were used for evaluation of mRNA expression levels of IL-4, IL-5, and IL-13.

RESULTS

Oxyresveratrol significantly reduced total leucocyte count in both blood and bronchoalveolar lavage fluid (BALF). Treatment with oxyresveratrol normalized altered eosinophil and neutrophil counts in both blood and BALF. OVA-specific T-cell response was also significantly inhibited by oxyresveratrol. A significant attenuation of inflammatory cell infiltration and goblet cell hyperplasia was observed after treatment with oxyresveratrol. Data showed that oxyresveratrol significantly suppressed Th2 (T helper cells) type immune response which was obvious by the reduction in mRNA expression levels of IL-4, IL-5, and IL-13. Similarly, treatment with methylprednisolone also significantly reduced all the immunomodulatory and inflammatory parameters.

CONCLUSIONS

Our study demonstrates that oxyresveratrol ameliorates allergic asthma. The anti-asthmatic activity might in part occur via the down regulation of IL-4, IL-5, and IL-13 expression levels.

Differential activation of airway eosinophils induces IL-13-mediated allergic Th2 pulmonary responses in mice

BACKGROUND

Eosinophils are hallmark cells of allergic Th2 respiratory inflammation. However, the relative importance of eosinophil activation and the induction of effector functions such as the expression of IL-13 to allergic Th2 pulmonary disease remain to be defined.

METHODS

Wild-type or cytokine-deficient (IL-13(-/-) or IL-4(-/-) ) eosinophils treated with cytokines (GM-CSF, IL-4, IL-33) were adoptively transferred into eosinophil-deficient recipient mice subjected to allergen provocation using established models of respiratory inflammation. Allergen-induced pulmonary changes were assessed.

RESULTS

In contrast to the transfer of untreated blood eosinophils to the lungs of recipient eosinophil deficient mice, which induced no immune/inflammatory changes either in the lung or in the lung draining lymph nodes (LDLN), pretreatment of blood eosinophils with GM-CSF prior to transfer elicited trafficking of these eosinophils to LDLN. In turn, these LDLN eosinophils elicited the accumulation of dendritic cells and CD4(+) T cells to these same LDLNs without inducing pulmonary inflammation. However, exposure of eosinophils to GM-CSF, IL-4, and IL-33 prior to transfer induced not only immune events in the LDLN, but also allergen-mediated increases in airway Th2 cytokine/chemokine levels, the subsequent accumulation of CD4(+) T cells as well as alternatively activated (M2) macrophages, and the induction of pulmonary histopathologies. Significantly, this allergic respiratory inflammation was dependent on eosinophil-derived IL-13, whereas IL-4 expression by eosinophils had no significant role.

CONCLUSION

The data demonstrate the differential activation of eosinophils as a function of cytokine exposure and suggest that eosinophil-specific IL-13 expression by activated cells is a necessary component of the subsequent allergic Th2 pulmonary pathologies.

Transcription Factor Repertoire of Homeostatic Eosinophilopoiesis

The production of mature eosinophils (Eos) is a tightly orchestrated process with the aim to sustain normal Eos levels in tissues while also maintaining low numbers of these complex and sensitive cells in the blood. To identify regulators of homeostatic eosinophilopoiesis in mice, we took a global approach to identify genome-wide transcriptome and epigenome changes that occur during homeostasis at critical developmental stages, including Eos-lineage commitment and lineage maturation. Our analyses revealed a markedly greater number of transcriptome alterations associated with Eos maturation (1199 genes) than with Eos-lineage commitment (490 genes), highlighting the greater transcriptional investment necessary for differentiation. Eos-lineage-committed progenitors (EoPs) were noted to express high levels of granule proteins and contain granules with an ultrastructure distinct from that of mature resting Eos. Our analyses also delineated a 976-gene Eos-lineage transcriptome that included a repertoire of 56 transcription factors, many of which have never previously been associated with Eos. EoPs and Eos, but not granulocyte-monocyte progenitors or neutrophils, expressed Helios and Aiolos, members of the Ikaros family of transcription factors, which regulate gene expression via modulation of chromatin structure and DNA accessibility. Epigenetic studies revealed a distinct distribution of active chromatin marks between genes induced with lineage commitment and genes induced with cell maturation during Eos development. In addition, Aiolos and Helios binding sites were significantly enriched in genes expressed by EoPs and Eos with active chromatin, highlighting a potential novel role for Helios and Aiolos in regulating gene expression during Eos development.

Toll-like receptor 7 governs interferon and inflammatory responses to rhinovirus and is suppressed by IL-5-induced lung eosinophilia

Background

Asthma exacerbations represent a significant disease burden and are commonly caused by rhinovirus (RV), which is sensed by Toll-like receptors (TLR) such as TLR7. Some asthmatics have impaired interferon (IFN) responses to RV, but the underlying mechanisms of this clinically relevant observation are poorly understood.

Objectives

To investigate the importance of intact TLR7 signalling in vivo during RV exacerbation using mouse models of house dust mite (HDM)-induced allergic airways disease exacerbated by a superimposed RV infection.

Methods

Wild-type and TLR7-deficient (Tlr7^−/−) BALB/c mice were intranasally sensitised and challenged with HDM prior to infection with RV1B. In some experiments, mice were administered recombinant IFN or adoptively transferred with plasmacytoid dendritic cells (pDC).

Results

Allergic Tlr7^−/− mice displayed impaired IFN release upon RV1B infection, increased virus replication and exaggerated eosinophilic inflammation and airways hyper reactivity. Treatment with exogenous IFN or adoptive transfer of TLR7-competent pDCs blocked these exaggerated inflammatory responses and boosted IFNγ release in the absence of host TLR7 signalling. TLR7 expression in the lungs was suppressed by allergic inflammation and by interleukin (IL)-5-induced eosinophilia in the absence of allergy. Subjects with moderate-to-severe asthma and eosinophilic but not neutrophilic airways inflammation, despite inhaled steroids, showed reduced TLR7 and IFNλ2/3 expression in endobronchial biopsies. Furthermore, TLR7 expression inversely correlated with percentage of sputum eosinophils.

Conclusions

This implicates IL-5-induced airways eosinophilia as a negative regulator of TLR7 expression and antiviral responses, which provides a molecular mechanism underpinning the effect of eosinophil-targeting treatments for the prevention of asthma exacerbations.

Re-defining the unique roles for eosinophils in allergic respiratory inflammation

The role of eosinophils in the progression and resolution of allergic respiratory inflammation is poorly defined despite the commonality of their presence and in some cases their use as a biomarker for disease severity and/or symptom control. However, this ambiguity belies the wealth of insights that have recently been gained through the use of eosinophil-deficient/attenuated strains of mice that have demonstrated novel immunoregulatory and remodelling/repair functions for these cells in the lung following allergen provocation. Specifically, studies of eosinophil-deficient mice suggest that eosinophils contribute to events occurring in the lungs following allergen provocation at several key moments: (i) the initiating phase of events leading to Th2-polarized pulmonary inflammation, (ii) the suppression Th1/Th17 pathways in lung-draining lymph nodes, (iii) the recruitment of effector Th2 T cells to the lung, and finally, (iv) mechanisms of inflammatory resolution that re-establish pulmonary homoeostasis. These suggested functions have recently been confirmed and expanded upon using allergen provocation of an inducible eosinophil-deficient strain of mice (iPHIL) that demonstrated an eosinophil-dependent mechanism(s) leading to Th2 dominated immune responses in the presence of eosinophils in contrast to neutrophilic as well as mixed Th1/Th17/Th2 variant phenotypes in the absence of eosinophils. These findings highlighted that eosinophils are not exclusively downstream mediators controlled by T cells, dendritic cells (DC) and/or innate lymphocytic cells (ILC2). Instead, eosinophils appear to be more aptly described as significant contributors in complex interrelated pathways that lead to pulmonary inflammation and subsequently promote resolution and the re-establishment of homoeostatic baseline. In this review, we summarize and put into the context the evolving hypotheses that are now expanding our understanding of the roles eosinophils likely have in the lung following allergen provocation.

Eosinophils in mucosal immune responses

Eosinophils, multifunctional cells that contribute to both innate and adaptive immunity, are involved in the initiation, propagation, and resolution of immune responses, including tissue repair. They achieve this multifunctionality by expression of a diverse set of activation receptors, including those that directly recognize pathogens and opsonized targets, and by their ability to store and release preformed cytotoxic mediators that participate in host defense, to produce a variety of de novo pleotropic mediators and cytokines, and to interact directly and indirectly with diverse cell types, including adaptive and innate immunocytes and structural cells. Herein, we review the basic biology of eosinophils and then focus on new emerging concepts about their role in mucosal immune homeostasis, particularly maintenance of intestinal IgA. We review emerging data about their development and regulation and describe new concepts concerning mucosal eosinophilic diseases. We describe recently developed therapeutic strategies to modify eosinophil levels and function and provide collective insight about the beneficial and detrimental functions of these enigmatic cells.

CCL7 and IRF-7 Mediate Hallmark Inflammatory and IFN Responses following Rhinovirus 1B Infection

Rhinovirus (RV) infections are common and have the potential to exacerbate asthma. We have determined the lung transcriptome in RV strain 1B-infected naive BALB/c mice (nonallergic) and identified CCL7 and IFN regulatory factor (IRF)-7 among the most upregulated mRNA transcripts in the lung. To investigate their roles we employed anti-CCL7 Abs and an IRF-7-targeting small interfering RNA in vivo. Neutralizing CCL7 or inhibiting IRF-7 limited neutrophil and macrophage influx and IFN responses in nonallergic mice. Neutralizing CCL7 also reduced activation of NF-κB p65 and p50 subunits, as well as airway hyperreactivity (AHR) in nonallergic mice. However, neither NF-κB subunit activation nor AHR was abolished with infection of allergic mice after neutralizing CCL7, despite a reduction in the number of neutrophils, macrophages, and eosinophils. IRF-7 small interfering RNA primarily suppressed IFN-α and IFN-β levels during infection of allergic mice. Our data highlight a pivotal role of CCL7 and IRF-7 in RV-induced inflammation and IFN responses and link NF-κB signaling to the development of AHR.

Bacillus subtilis KCTC 11782BP-produced alginate oligosaccharide effectively suppresses asthma via T-helper cell type 2-related cytokines

According to the World Health Organization in 2013, 235 million people are afflicted with asthma. Asthma is a severe pulmonary disease that can be caused by the imbalance of T-helper (Th) type 1 (Th1) and type 2 (Th2) cells, and it is potentially fatal. In this study, we evaluated the anti-asthmatic effect of alginate oligosaccharide (AO), which was prepared from seaweed and converted by Bacillus subtilis KCTC 11782BP, in the mouse model of ovalbumin (OVA)-induced asthma. BALB/c mice were divided into the vehicle control (sensitized but not challenged), asthma induction, positive control (1 mg/kg dexamethasone), 50 mg/kg/day AO-treated, 200 mg/kg/day AO-treated, and 400 mg/kg/day AO-treated groups. The numbers or levels of inflammatory cells, eosinophils, and immunoglobulin (Ig) E were measured in bronchoalveolar lavage fluid (BALF), and asthma-related morphological and cytokine changes were analyzed in lung tissues. Our results show that AO dramatically reduced inflammatory cell numbers, eosinophil count, and IgE levels in BALF, and it dose-dependently inhibited asthmatic histopathological changes in the lung. In addition, AO dose-dependently suppressed the expression of CD3+ T-cell co-receptors, CD4+ Th cells, CD8+ cytotoxic T-cell-related factors, macrophages, and MHCII class. AO dose-dependently decreased the expression levels of Th1/2 cells-regulatory transcription factors such as GATA-3 which modulates Th2 cell proliferation and T-bet which does Th1 cell proliferation. The mRNA levels of all Th1/2-related cytokines, except IL-12α, were dose-dependently suppressed by AO treatment. In particular, the mRNA levels of IL-5, IL-6, and IL-13 were significantly inhibited by AO treatment. Our findings suggest that AO has the potential to be an anti-asthmatic drug candidate, due to its modulation of Th1/Th2 cytokines, which contribute to the pathogenesis of asthma.

The chemokine system in innate immunity

Chemokines are chemotactic cytokines that control the migration and positioning of immune cells in tissues and are critical for the function of the innate immune system. Chemokines control the release of innate immune cells from the bone marrow during homeostasis as well as in response to infection and inflammation. They also recruit innate immune effectors out of the circulation and into the tissue where, in collaboration with other chemoattractants, they guide these cells to the very sites of tissue injury. Chemokine function is also critical for the positioning of innate immune sentinels in peripheral tissue and then, following innate immune activation, guiding these activated cells to the draining lymph node to initiate and imprint an adaptive immune response. In this review, we will highlight recent advances in understanding how chemokine function regulates the movement and positioning of innate immune cells at homeostasis and in response to acute inflammation, and then we will review how chemokine-mediated innate immune cell trafficking plays an essential role in linking the innate and adaptive immune responses.

Pro-inflammatory role of natural killer cells in the development of allergic airway disease

BACKGROUND

Natural Killer (NK) cells have been implicated in the development of allergic airway inflammation. However, the in vivo role of NK cells has not been firmly established due to the lack of animal models with selective deficiencies in NK cells.

OBJECTIVE

To determine the specific contribution of NK cells in a murine model of allergic airway disease (AAD).

METHODS

The role of NK cells in AAD was studied using NK-deficient (NKD) mice, perforin(-/-) mice, and mice depleted of Ly49A/D/G(+) NK cell subsets in an ovalbumin-induced model of allergic airway disease (OVA-AAD).

RESULTS

Induction of OVA-AAD in C57BL/6 wild-type (WT) mice resulted in the expansion of airway NK cells and the development of pronounced airway eosinophilia. In the absence of NK cells or specific subsets of NK cells, either in NKD mice, or after the depletion of Ly49A/D/G(+) NK cells, the development of OVA-AAD was significantly impaired as seen by decreased airway inflammation and eosinophilia, decreased secretion of the Th2 cytokines IL-4, IL-5 and IL-13 and diminished OVA-specific antibody production. Furthermore, while OVA-exposure induced a dramatic expansion of dendritic cells (DCs) in WT mice, their induction was significantly attenuated in NKD mice. Development of OVA-AAD in perforin(-/-) mice suggested that the proinflammatory role of NK cells is not dependent on perforin-mediated cytotoxicity. Lastly, induction of allergic disease by OVA-specific CD4 T cells from WT but not NK-depleted or NKD mice in RAG(-/-) recipients, demonstrates that NK cells are essential for T cell priming.

CONCLUSIONS AND CLINICAL RELEVANCE

Our data demonstrate that conventional NK cells play an important and distinct role in the development of AAD. The presence of activated NK cells has been noted in patients with asthma. Understanding the mechanisms by which NK cells regulate allergic disease is therefore an important component of treatment approaches.

Dual proinflammatory and antiviral properties of pulmonary eosinophils in respiratory syncytial virus vaccine-enhanced disease

Human respiratory syncytial virus (RSV) is a major cause of morbidity and severe lower respiratory tract disease in the elderly and very young, with some infants developing bronchiolitis, recurrent wheezing, and asthma following infection. Previous studies in humans and animal models have shown that vaccination with formalin-inactivated RSV (FI-RSV) leads to prominent airway eosinophilic inflammation following RSV challenge; however, the roles of pulmonary eosinophilia in the antiviral response and in disease pathogenesis are inadequately understood. In vivo studies in mice with eotaxin and/or interleukin 5 (IL-5) deficiency showed that FI-RSV vaccination did not lead to enhanced pulmonary disease, where following challenge there were reduced pulmonary eosinophilia, inflammation, Th2-type cytokine responses, and altered chemokine (TARC and CCL17) responses. In contrast to wild-type mice, RSV was recovered at high titers from the lungs of eotaxin- and/or IL-5-deficient mice. Adoptive transfer of eosinophils to FI-RSV-immunized eotaxin- and IL-5-deficient (double-deficient) mice challenged with RSV was associated with potent viral clearance that was mediated at least partly through nitric oxide. These studies show that pulmonary eosinophilia has dual outcomes: one linked to RSV-induced airway inflammation and pulmonary pathology and one with innate features that contribute to a reduction in the viral load.

IMPORTANCE

This study is critical to understanding the mechanisms attributable to RSV vaccine-enhanced disease. This study addresses the hypothesis that IL-5 and eotaxin are critical in pulmonary eosinophil response related to FI-RSV vaccine-enhanced disease. The findings suggest that in addition to mediating tissue pathology, eosinophils within a Th2 environment also have antiviral activity.

SPINK5 and ADRB2 haplotypes are risk factors for asthma in Mexican pediatric patients

BACKGROUND

Asthma is one of the most common respiratory diseases worldwide, and the complexity of its etiology has been widely documented. Chromosome 5q31-33 is one of the main loci implicated in asthma and asthma-related traits. IL13, CD14 and ADRB2, which are located in this risk locus, are among the genes most strongly associated with asthma susceptibility.

OBJECTIVES

This study evaluated whether single-nucleotide polymorphisms or haplotypes at 5q31-33 conferred risk for asthma in Mexican-Mestizo pediatric patients.

METHODS

We performed a case-controlled study including 851 individuals, 421 of them affected with childhood-onset asthma and 430 ethnically matched unaffected subjects. We used the TaqMan Allelic Discrimination Assay to genotype 20 single-nucleotide polymorphisms within IL5, RAD50, IL13, IL4, CD14, SPINK5, HTR4, ADRB2 and IL12B.

RESULTS

Although no association was detected for any risk allele, three SPINK5 haplotypes (GGCT: p = 6 × 10(-6); AATC: p = 0.0001; AGTT: p = 0.0001) and five ADRB2 haplotypes (AGGACC: p = 0.0014; AGGAAG: p = 0.0002; TGAGAG: p = 0.0001; AGGAAC: p = 0.0002; AAGGAG: p = 0.003) were associated with asthma. Notably, the AGTT SPINK5 haplotype exhibited a male gender-dependent association (p = 7.6 × 10(-5)).

CONCLUSION

Our results suggest that SPINK5 and ADRB2 haplotypes might play a role in the susceptibility to childhood-onset asthma.

Tumor necrosis factor-related apoptosis-inducing ligand regulates hallmark features of airways remodeling in allergic airways disease

Allergic asthma is a complex disease characterized by acute inflammation of the airways that over time leads to the development of significant structural changes termed remodeling. TNF-related apoptosis-inducing ligand (TRAIL) has an important regulatory role in acute allergic airways inflammation through up-regulation of the E3 ubiquitin ligase Midline-1 (MID-1), which limits protein phosphatase 2A (PP2A) activity and downstream dephosphorylation of proinflammatory signaling molecules. The relevance of TRAIL in the development of airways remodeling has yet to be determined. In this study, the lungs of wild-type (WT) BALB/c and Tnfsf10 knockout (TRAIL-/-) mice were chronically exposed to ovalbumin (OVA) for 12 weeks to induce hallmark features of chronic allergic airways disease, including airways hyperreactivity (AHR), subepithelial collagen deposition, goblet cell hyperplasia, and smooth muscle hypertrophy. TRAIL-/- mice were largely protected from the development of AHR and peribronchial eosinophilia and had reduced levels of mast cells in the airways. This correlated with lower levels of cytokines, including IL-4, -5, -10, and -13, and with lower levels of proinflammatory chemokines from cultured cells isolated from the draining lymph nodes. TRAIL-/- mice were also protected from the characteristic features of airways remodeling, including peribronchial fibrosis, smooth muscle hypertrophy, and mucus hypersecretion, which correlated with reduced TGF-β1 levels in the lungs. MID-1 expression was reduced in TRAIL-/- mice and up-regulated in allergic WT mice. Raising PP2A activity using 2-amino-4-(4-heptyloyphenol)-2-methylbutan-1-ol in allergic WT mice reduced eosinophilia, TGF-β1, and peribronchial fibrosis. This study shows that TRAIL promotes airways remodeling in an OVA-induced model of chronic allergic airways disease. Targeting TRAIL and its downstream proinflammatory signaling pathway involving PP2A may be of therapeutic benefit in reducing the hallmark features of airways remodeling observed in chronic allergic airways inflammation.

Intratracheal exposure to Fab fragments of an allergen-specific monoclonal antibody regulates asthmatic responses in mice

Fab fragments (Fabs) maintain the ability to bind to specific antigens but lack effector functions due to the absence of the Fc portion. In the present study, we tested whether Fabs of an allergen-specific monoclonal antibody (mAb) were able to regulate asthmatic responses in mice. Asthmatic responses were induced in BALB/c mice by passive sensitization with anti-ovalbumin (OVA) polyclonal antibodies (pAbs) (day 0) and by active sensitization with OVA (days 0 and 14), followed by intratracheal (i.t.) challenge with OVA on day 1 and days 28, 29, 30 and 35. Fabs prepared by the digestion of an anti-OVA IgG1 (O1-10) mAb with papain were i.t. administered only once 30 min before antigenic challenge on day 1 or day 35. The results showed that i.t. administration of O1-10 Fabs with OVA markedly suppressed the early and/or late phases of asthmatic responses caused by passive and active sensitization. Similar results were obtained when Fabs of anti-OVA IgG2b mAb (O2B-3) were i.t. administered. In contrast, neither i.t. injection of intact 01-10/O2B-3 nor systemic injection of O1-10 Fabs suppressed the asthmatic responses. In vitro studies revealed that the capture of OVA by O1-10 Fabs prevented the subsequent binding of intact anti-OVA pAbs to the captured OVA. These results suggest that asthmatic responses may be down-regulated by the i.t. exposure to Fabs of an allergen-specific mAb via a mechanism involving the capture of allergen by Fabs in the respiratory tract before the interaction of intact antibody and allergen essential for the induction of asthmatic responses.