Mycobacterium-Induced Th1, Helminths-Induced Th2 Cells and the Potential Vaccine Candidates for Allergic Asthma: Imitation of Natural Infection.

Bronchial asthma is one of the most chronic pulmonary diseases and major public health problems. In general, asthma prevails in developed countries than developing countries, and its prevalence is increasing in the latter. For instance, the hygiene hypothesis demonstrated that this phenomenon resulted from higher household hygienic standards that decreased the chances of infections, which would subsequently increase the occurrence of allergy. In this review, we attempted to integrate our knowledge with the hygiene hypothesis into beneficial preventive approaches for allergic asthma. Therefore, we highlighted the studies that investigated the correlation between allergic asthma and the two different types of infections that induce the two major antagonizing arms of T cells. This elucidation reflects the association between various types of natural infections and the immune system, which is predicted to support the main objective of the current research on investigating of the benefits of natural infections, regardless their immune pathways for the prevention of allergic asthma. We demonstrated that natural infection with Mycobacterium tuberculosis (Mtb) prevents the development of allergic asthma, thus Bacille Calmette-Guérin (BCG) vaccine is suggested at early age to mediate the same prevention particularly with increasing its efficiency through genetic engineering-based modifications. Likewise, natural helminth infections might inhabit the allergic asthma development. Therefore, helminth-derived proteins at early age are good candidates for designing vaccines for allergic asthma and it requires further investigation. Finally, we recommend imitation of natural infections as a general strategy for preventing allergic asthma that increased dramatically over the past decades.

Inactivation of common airborne antigens by perfluoroalkyl chemicals modulates early life allergic asthma.

Allergic asthma, driven by T helper 2 cell-mediated immune responses to common environmental antigens, remains the most common respiratory disease in children. Perfluorinated chemicals (PFCs) are environmental contaminants of great concern, because of their wide application, persistence in the environment, and bioaccumulation. PFCs associate with immunological disorders including asthma and attenuate immune responses to vaccines. The influence of PFCs on the immunological response to allergens during childhood is unknown. We report here that a major PFC, perfluorooctane sulfonate (PFOS), inactivates house dust mite (HDM) to dampen 5-wk-old, early weaned mice from developing HDM-induced allergic asthma. PFOS further attenuates the asthma protective effect of the microbial product lipopolysaccharide (LPS). We demonstrate that PFOS prevents desensitization of lung epithelia by LPS, thus abolishing the latter's protective effect. A close mechanistic study reveals that PFOS specifically binds the major HDM allergen Der p1 with high affinity as well as the lipid A moiety of LPS, leading to the inactivation of both antigens. Moreover, PFOS at physiological human (nanomolar) concentrations inactivates Der p1 from HDM and LPS in vitro, although higher doses did not cause further inactivation because of possible formation of PFOS aggregates. This PFOS-induced neutralization of LPS has been further validated in primary human cell models and extended to an in vivo bacterial infection mouse model. This study demonstrates that early life exposure of mice to a PFC blunts airway antigen bioactivity to modulate pulmonary inflammatory responses, which may adversely affect early pulmonary health.

Scavenger Receptor BI Attenuates IL-17A-Dependent Neutrophilic Inflammation in Asthma.

Asthma is a common respiratory disease currently affecting more than 300 million worldwide and is characterized by airway inflammation, hyperreactivity, and remodeling. It is a heterogeneous disease consisting of corticosteroid-sensitive T-helper cell type 2-driven eosinophilic and corticosteroid-resistant, T-helper cell type 17-driven neutrophilic phenotypes. One pathway recently described to regulate asthma pathogenesis is cholesterol trafficking. Scavenger receptors, in particular SR-BI (scavenger receptor class B type I), are known to direct cellular cholesterol uptake and efflux. We recently defined SR-BI functions in pulmonary host defense; however, the function of SR-BI in asthma pathogenesis is unknown. To elucidate the role of SR-BI in allergic asthma, SR-BI-sufficient (SR-BI+/+) and SR-BI-deficient (SR-BI-/-) mice were sensitized (Days 0 and 7) and then challenged (Days 14, 15, and 16) with a house dust mite (HDM) preparation administered through oropharyngeal aspiration. Airway inflammation and cytokine production were quantified on Day 17. When compared with SR-BI+/+ mice, the HDM-challenged SR-BI-/- mice had increased neutrophils and pulmonary IL-17A production in BAL fluid. This augmented IL-17A production in SR-BI-/- mice originated from a non-T-cell source that included neutrophils and alveolar macrophages. Given that SR-BI regulates adrenal steroid hormone production, we tested whether the changes in SR-BI-/- mice were glucocorticoid dependent. Indeed, SR-BI-/- mice were adrenally insufficient during the HDM challenge, and corticosterone replacement decreased pulmonary neutrophilia and IL-17A production in SR-BI-/- mice. Taken together, these data indicate that SR-BI dampens pulmonary neutrophilic inflammation and IL-17A production in allergic asthma at least in part by maintaining adrenal function.

Dysregulation of Pyruvate Kinase M2 Promotes Inflammation in a Mouse Model of Obese Allergic Asthma.

Obesity is a risk factor for the development of asthma and represents a difficult-to-treat disease phenotype. Aerobic glycolysis is emerging as a key feature of asthma, and changes in glucose metabolism are linked to leukocyte activation and adaptation to oxidative stress. Dysregulation of PKM2 (pyruvate kinase M2), the enzyme that catalyzes the last step of glycolysis, contributes to house dust mite (HDM)-induced airway inflammation and remodeling in lean mice. It remains unclear whether glycolytic reprogramming and dysregulation of PKM2 also contribute to obese asthma. The goal of the present study was to elucidate the functional role of PKM2 in a murine model of obese allergic asthma. We evaluated the small molecule activator of PKM2, TEPP46, and assessed the role of PKM2 using conditional ablation of the Pkm2 allele from airway epithelial cells. In obese C57BL/6NJ mice, parameters indicative of glycolytic reprogramming remained unchanged in the absence of stimulation with HDM. Obese mice that were subjected to HDM showed evidence of glycolytic reprogramming, and treatment with TEPP46 diminished airway inflammation, whereas parameters of airway remodeling were unaffected. Epithelial ablation of Pkm2 decreased central airway resistance in both lean and obese allergic mice in addition to decreasing inflammatory cytokines in the lung tissue. Lastly, we highlight a novel role for PKM2 in the regulation of glutathione-dependent protein oxidation in the lung tissue of obese allergic mice via a putative IFN-γ-glutaredoxin1 pathway. Overall, targeting metabolism and protein oxidation may be a novel treatment strategy for obese allergic asthma.

Chronic strongyloidiasis: a case of B symptoms and recurrent asthma exacerbations.

Strongyloidiasis is one of the neglected helminths infection that is often underdiagnosed and undertreated. Due to its variable presentation, its diagnosis is often a challenge. We report a case of an immigrant patient with asthma who later developed eosinophilia. After 3 years of unexplained eosinophilia, he developed B symptoms and had frequent asthma exacerbations. He was later diagnosed with strongyloidiasis and treated with ivermectin. His B symptoms resolved, and his asthma exacerbations decreased significantly. Due to the frequent use of corticosteroids in asthma exacerbations, this case illustrates the importance of Strongyloides screening in asthmatics from high-risk regions. It also displays the importance of further investigating patients with asthma who develop eosinophilia and have frequent exacerbations while on optimal asthma treatment. Having a high index of suspicion is essential when making this diagnosis, as clinical presentation is often variable and does not follow a standard time course.

TNF-α (rs1800629) polymorphism modifies the effect of sensitization to house dust mite on asthma and bronchial hyperresponsiveness in children.

Asthma is a complex disease, with various genetic and environmental factors implicated in its development. Sensitization to the house dust mite (HDM) is closely linked with the development of respiratory allergies, including asthma. However, some children sensitized to HDM do not complain of any symptoms of respiratory allergies, even though HDM is correlated with an increased risk for developing asthma, suggesting the involvement of other factors. Tumor necrosis factor (TNF)-α is associated with the pathophysiologies of asthma in combination with its genetic polymorphism. The aim of the present study was to elucidate the associations between sensitization to HDM, polymorphism of TNF-α rs1800629, and asthma/bronchial hyperresponsiveness (BHR). Our results revealed that sensitization to HDM is associated with asthma diagnosis in lifetime, current asthma, and BHR in Korean children. Furthermore, the genetic polymorphism of TNF-a rs1800629 was found to modify and interact with these associations. This study suggests that prevention strategies for childhood asthma need to be targeted according to genetic susceptibility.

Group 2 Innate Lymphoid Cells and the House Dust Mite-Induced Asthma Mouse Model.

Asthma is an important issue not only in health but also in economics worldwide. Therefore, asthma animal models have been frequently used to understand the pathogenesis of asthma. Recently, in addition to acquired immunity, innate immunity has also been thought to be involved in asthma. Among innate immune cells, group 2 innate lymphoid cells (ILC2s) have been considered to be crucial for eosinophilic airway inflammation by releasing T helper 2 cytokines. Moreover, house dust mites (HDMs) belonging to group 1 act on airway epithelial cells not only as allergens but also as cysteine proteases. The production of interleukin-25 (IL-25), IL-33, and thymic stromal lymphopoietin (TSLP) from airway epithelial cells was induced by the protease activity of HDMs. These cytokines activate ILC2s, and activated ILC2s produce IL-5, IL-9, IL-13, and amphiregulin. Hence, the HDM-induced asthma mouse model greatly contributes to understanding asthma pathogenesis. In this review, we highlight the relationship between ILC2s and the HDM in the asthma mouse model to help researchers and clinicians not only choose a proper asthma mouse model but also to understand the molecular mechanisms underlying HDM-induced asthma.

The importance of reporting house dust mite endotoxin abundance: impact on the lung transcriptome.

The abundance of lipopolysaccharide (LPS) in house dust mite (HDM) preparations is broad and mirrors the variability seen in the homes of people with asthma. LPS in commercially available stocks ranges from 31 to 5,2000 endotoxin units. The influence of vastly different LPS loads on the mechanisms that define the immune and inflammatory phenotype of HDM-challenged mice has not been defined. This aim of the study was to understand the lung phenotype of mice challenged with HDM extract containing high or low levels of LPS. Female BALB/c mice were sensitized for 2 wk with commercial HDM extract containing either high (36,000 endotoxin units; HHDM) or low (615 endotoxin units; LHDM) levels of LPS. Lung phenotype was characterized by measuring lung function, total and differential cell counts, cytokine abundance, and the lung transcriptome by RNA-sequencing. LPS levels in HDM stocks used for preclinical asthma research in mice remain poorly reported. In 2019, only 14% of papers specified LPS concentration in HDM lots. Specific differences existed in airway responsiveness between mice challenged with HHDM or LHDM. HHDM- and LHDM-induced cytokine profiles of bronchial lavage were significantly different and the lung transcriptome was differentially enriched for genes involved in DNA damage repair or cilium movement, following HHDM or LHDM challenge, respectively. The abundance of LPS in commercially available HDM influences the phenotype of allergic airways inflammation in mice. Failure to report the level of LPS in HDM extracts used in animal models of airway disease will lead to inconsistency in reproducibility and reliability of published data.

Frontline Science: Two flavonoid compounds attenuate allergic asthma by regulating epithelial barrier via G protein-coupled estrogen receptor: Probing a possible target for allergic inflammation.

Allergic asthma is a common chronic lung inflammatory disease and seriously influences public health. We aim to investigate the effects of formononetin (FMN) and calycosin (CAL), 2 flavonoids in Radix Astragali, on allergic asthma and elucidate possible therapeutic targets. A house dust mite (HDM)-induced allergic asthma mouse model and TNF-α and Poly(I:C) co-stimulated human bronchial epithelial cell line (16HBE) were performed respectively in vivo and in vitro. The role of G protein-coupled estrogen receptor (GPER) was explored by its agonist, antagonist, or GPER small interfering RNA (siGPER). E-cadherin, occludin, and GPER were detected by western blotting, immunohistochemistry, or immunofluorescence. The epithelial barrier integrity was assessed by trans-epithelial electric resistance (TEER). Cytokines were examined by enzyme-linked immunosorbent assay (ELISA). The results showed that flavonoids attenuated pulmonary inflammation and hyperresponsiveness in asthmatic mice. These flavonoids significantly inhibited thymic stromal lymphopoietin (TSLP), increased occludin and restored E-cadherin in vivo and in vitro. The effects of flavonoids on occludin and TSLP were not interfered by ICI182780 (estrogen receptor antagonist), while blocked by G15 (GPER antagonist). Furthermore, compared with PPT (ERα agonist) and DPN (ERß agonist), G1 (GPER agonist) significantly inhibited TSLP, up-regulated occludin, and restored E-cadherin. siGPER and TEER assays suggested that GPER was pivotal for the flavonoids on the epithelial barrier integrity. Finally, G1 attenuated allergic lung inflammation, which could be abolished by G15. Our data demonstrated that 2 flavonoids in Radix Astragali could alleviate allergic asthma by protecting epithelial integrity via regulating GPER, and activating GPER might be a possible therapeutic strategy against allergic inflammation.

Seropositivity and risk factors of Toxocara canis infection in adult asthmatic patients.

This cross-sectional study involving 86 adult asthmatic patients aimed to determine the relationship between Toxocara seropositivity and severity of asthma in adult asthmatics and investigate the risk factors for Toxocara infection. In all cases, T. canis IgG level was measured using an anti-Toxocara IgG enzyme-linked immunosorbent assay kit. Total serum IgE and eosinophil count were also determined. The anti-Toxocara IgG seropositivity was 68.6% among asthmatic patients. There were no statistically significant associations between Toxocara seroprevalence and other risk factors, clinical symptoms of asthma and high level of total serum IgE and eosinophilia. Pet ownership could be an important risk factor for Toxocariasis. Having a pet at home and wheezing were significantly associated with Toxocara seropositivity in adult asthmatic patients.

Cytokine production in allergic and Trichuris trichiura-infected children from an urban region of the Brazilian northeast.

The relationship between the cellular immune response during Trichuris trichiura infection and asthma has not yet been established. In this study, the cytokines interleukin (IL)-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ and IL-17A were evaluated in asthmatic children harboring T. trichiura. For this assessment, asthmatic and non-asthmatic children (ISAAC questionnaire) were submitted to parasitological tests and blood samples were cultured (mitogen stimulation) for cytokine measurements in the supernatant. Asthma frequencies were similar in infected and uninfected children, but IL-4, IL-6, TNF-α and IL-10 levels were high in the infected asthmatic children. Additionally, infected non-asthmatic children exhibited high levels of these cytokines in relation to uninfected non-asthmatic children; however, cytokine levels were lower when compared with infected and asthmatic children. Therefore, T. trichiura infection positively modulated the pro- and anti-inflammatory cytokines in asthmatic children, but a background of asthma seemed to narrow the production of cytokines induced by this helminth.

Critical roles of regulatory B and T cells in helminth parasite-induced protection against allergic airway inflammation.

The prevalence of allergic asthma and incidences of helminth infections in humans are inversely correlated. Although experimental studies have established the causal relation between parasite infection and allergic asthma, the mechanism of the parasite-associated immunomodulation is not fully elucidated. Using a murine model of asthma and nematode parasite Heligmosomoides polygyrus, we investigated the roles of regulatory B cells (Breg ) and T cells (Treg ) in mediation of the protection against allergic asthma by parasite. H. polygyrus infection significantly suppressed ovalbumin (OVA)-induced allergic airway inflammation (AAI) evidenced by alleviated lung histopathology and reduced numbers of bronchoalveolar inflammatory cell infiltration, and induced significant responses of interleukin (IL)-10+ Breg , IL-10+ Treg and forkhead box protein 3 (FoxP3)+ Treg in mesenteric lymph node and spleen of the mice. Adoptive transfer of IL-10+ Breg and IL-10+ Treg cell prevented the lung immunopathology in AAI mice. Depletion of FoxP3+ Treg cells in FoxP3-diphtheria toxin (DT) receptor transgenic mice by diphtheria toxin (DT) treatment exacerbated airway inflammation in parasite-free AAI mice and partially abrogated the parasite-induced protection against AAI. IL-10+ Breg cells were able to promote IL-10+ Treg expansion and maintain FoxP3+ Treg cell population. These two types of Tregs failed to induce CD19+ B cells to transform into IL-10+ Breg cells. These results demonstrate that Breg , IL-10+ Treg and FoxP3+ Treg cells contribute in A discrepant manner to the protection against allergic airway immunopathology by parasiteS. Breg cell might be a key upstream regulatory cell that induces IL-10+ Treg response and supports FoxP3+ Treg cell population which, in turn, mediate the parasite-imposed immunosuppression of allergic airway inflammation. These results provide insight into the immunological relationship between parasite infection and allergic asthma.

TLR9 agonist adsorbed to alum adjuvant prevents asthma-like responses induced by Blomia tropicalis mite extract.

Blomia tropicalis mite is highly prevalent in tropical and subtropical regions and it is associated with allergic diseases such as rhinitis and asthma. By using an OVA-model of allergic lung disease, we have previously shown that sensitization in the presence of toll like receptors (TLRs) agonists attenuates subsequent OVA-induced allergic responses. Here, we evaluated the effect of CpG-ODN, a specific synthetic TLR-9 agonist, on the development of experimental asthma induced by Blomia tropicalis extract, a relevant source of aeroallergens. Among different protocols of Blomia tropicalis extract sensitization, the subcutaneous sensitization in the presence of alum adjuvant induced the highest Th2 responses, including high IgE levels. Adsorption of CpG to Blomia tropicalis extract/Alum attenuated the airway hyperreactivity, the infiltration of inflammatory cells including eosinophils, and the IL-5 content in BAL. In addition, lung peribronchial inflammatory infiltrate, mucus production and IL-5-producing CD3+ CD4+ T cells were significantly reduced in the Blomia tropicalis extract/Alum+CpG group. Importantly, CpG inhibited total IgE production as well as active systemic or cutaneous anaphylaxis reactions. Inhibition of pulmonary Th2 responses was associated with increased IL-10 production but not with IFN-γ production. Notably, in IL-10-deficient mice, sensitization with OVA/Alum+CpG resulted in intense lung neutrophilia and IFN-γ production, indicating that IL-10 is necessary to inhibit subsequent Th1 immunity. Our work highlights the mechanisms of allergy attenuation by CpG and it indicates the potential use of Alum-based formulation with CpG to treat allergic processes.

Rho-kinase inhibitor attenuates airway mucus hypersecretion and inflammation partly by downregulation of IL-13 and the JNK1/2-AP1 signaling pathway.

We measured the effect of Rho-kinase on inflammation and mucus hypersecretion in the airways of mouse models of asthma. Additionally, we aimed to determine if these effects were the result of JNK 1/2-AP1 pathway inhibition.We sensitized and challenged female C57BL/6 mice using house dust mites (HDM) followed by treatment with an inhibitor of Rho-kinase. Lung tissue was harvested to evaluate inflammation and mucus secretion in the airways of asthma mice. Cytokine expression in broncho-alveolar lavage fluid (BALF) was established by ELISA and airway responsiveness, and was determined by the invasive lung function test. JNK1/2, p-JNK1/2, AP-1, and p-AP-1 protein expression was determined by Western blot analysis. Asthma model mice that were treated with Rho-kinase inhibitor showed a significantly decrease in inflammation score, inflammatory cells, and airway responsiveness. Additionally, we found that IL-13 expressions in BALF and mucus secretion were decreased in HDM-challenged mice treated with Rho-kinase inhibitor. Furthermore, Rho-kinase inhibitor treatment decreased the expression of JNK1/2 and AP-1 phosphorylation. Our findings indicated that the Rho-kinase inhibitor decreased HDM-induced mucus secretion as well as airway inflammation in asthma mice through regulation of the JNK1/2-AP-1 pathway.

Variants in the CYSLTR2 are associated with asthma, atopy markers and helminths infections in the Brazilian population.

BACKGROUND: Asthma is a chronic disease of the airways and its most common phenotype is characterized by a T2 type response with IgE production and inflammatory mediators in response to common allergens. Cysteinyl leukotrienes (CysLTs), LTC4, LTD4 and LTE4, are mediators known to possess important proinflammatory action. CysLTs can bind to the Cysteinyl leukotriene receptor type 2 (CysLTR2) and activate an inflammatory. Polymorphisms in CysLTR2 have been associated with asthma and atopy, although the mechanism is not clear. OBJECTIVE: To evaluate the association between genetic polymorphisms in CYSLTR2 with asthma phenotypes, atopy markers and helminth infection. METHODS: Genotyping was performed using a panel Illumina and carried out in 1245 participants of SCAALA program (Social Change, Asthma, Allergy in Latin American). Logistic regressions for asthma, helminth infections (Trichuris trichiura and Ascaris lumbricoides) and allergy markers (skin tests and IgE production) were performed using PLINK 1.9 software adjusted for sex, age, helminth infection and ancestry markers. RESULTS: The G allele of rs1323556 was negatively associated with asthma in the additive model (OR 0.74, 95% CI 0.59-0.93) and in the dominant model (OR 0.71, 95% CI 0.53-0.74). The G allele of rs1575464 was also negatively associated with asthma in two genetic models, additive (OR 0.77, 95% CI 0.62-0.96) and dominant (OR 0.73, 95% CI 0.55-0.97). The G allele of rs61735175 was positively associated with asthma severity in the additive model (OR 1.72, 95% CI 1.07-2.77) and in the dominant model (OR 1.77, 95% CI 1.09-2.85). Five SNVs were associated with atopy markers and four SNVs were associated with helminth infections. CONCLUSION: Polymorphisms in the CYSLTR2 gene are associated with asthma, atopy markers and helminth infection in Brazilian individuals, which may lead to protection or risk for such conditions, however, more studies are needed to evaluate the functional of this variants here in described.

Kinetics of the accumulation of group 2 innate lymphoid cells in IL-33-induced and IL-25-induced murine models of asthma: a potential role for the chemokine CXCL16.

ILC2s are implicated in asthma pathogenesis, but little is known about the mechanisms underlying their accumulation in airways. We investigated the time course of ILC2 accumulation in different tissues in murine models of asthma induced by a serial per-nasal challenge with ovalbumin (OVA), house dust mice (HDM), IL-25 and IL-33 and explored the potential roles of ILC2-attracting chemokines in this phenomenon. Flow cytometry was used to enumerate ILC2s at various time points. The effects of cytokines and chemokines on ILC2 migration were measured in vitro using a chemotaxis assay and in vivo using small animal imaging. Compared with saline and OVA challenge, both IL-25 and IL-33 challenge alone induced significant accumulation of ILC2s in the mediastinal lymph nodes, lung tissue and bronchoalveolar lavage fluid of challenged animals, but with a distinct potency and kinetics. In vitro, IL-33 and CXCL16, but not IL-25 or CCL25, directly induced ILC2 migration. Small animal in vivo imaging further confirmed that a single intranasal provocation with IL-33 or CXCL16 was sufficient to induce the accumulation of ILC2s in the lungs following injection via the tail vein. Moreover, IL-33-induced ILC2 migration involved the activation of ERK1/2, p38, Akt, JNK and NF-κB, while CXCL16-induced ILC2 migration involved the activation of ERK1/2, p38 and Akt. These data support the hypothesis that epithelium-derived IL-25 and IL-33 induce lung accumulation of ILC2s, while IL-33 exerts a direct chemotactic effect in this process. Although ILC2s express the chemokine receptors CXCR6 and CCR9, only CXCL16, the ligand of CXCR6, exhibits a direct chemoattractant effect.

Toxocara sero-prevalence and its relationship with allergic asthma in asthmatic patients in north-eastern Iran.

Toxocariasis is an important neglected tropical disease that has been suggested as a possible etiologic agent of asthma. The objective of the present study was to investigate possible significant association between Toxocara seroprevalence and asthma in a clinic-based case-control study. Blood samples were collected from human subjects aged 5-70 years, 50 of whom had signs of asthma and 50 of whom had no signs of asthma. Risk factors for asthma and Toxocara spp. infection were assessed by a questionnaire given to each patient. Blood samples were analysed to measure levels of anti-Toxocara spp. immunoglobulin G (IgG). Patients with bronchial asthma were observed to have higher Toxocara spp. seropositivity than that of the non-asthmatic controls (6 vs 2%, P = 0.47). The mean anti-Toxocara spp. antibody titre was not significantly higher in patients with bronchial asthma than in individuals without asthma (P = 0.395, 95% CI = 0.579-1.45). There was no significant difference in the mean age, sex, social class, exposure to smoking and presence of domestic dog or cat at home between the two groups (P ≥ 0.05). The presence of anti-Toxocara spp. IgG was statistically associated with higher blood eosinophils, but it was not associated with asthma (P ≥ 0.05). The observed relationship between exposure to Toxocara spp. infection and bronchial asthma in Iranian patients warrants further evaluation. An understanding of any potential influence on the pathogenesis of human asthma provides a potential avenue for prevention.

House dust mite drives proinflammatory eicosanoid reprogramming and macrophage effector functions.

BACKGROUND: Eicosanoid lipid mediators play key roles in type 2 immune responses, for example in allergy and asthma. Macrophages represent major producers of eicosanoids and they are key effector cells of type 2 immunity. We aimed to comprehensively track eicosanoid profiles during type 2 immune responses to house dust mite (HDM) or helminth infection and to identify mechanisms and functions of eicosanoid reprogramming in human macrophages. METHODS: We established an LC-MS/MS workflow for the quantification of 52 oxylipins to analyze mediator profiles in human monocyte-derived macrophages (MDM) stimulated with HDM and during allergic airway inflammation (AAI) or nematode infection in mice. Expression of eicosanoid enzymes was studied by qPCR and western blot and cytokine production was assessed by multiplex assays. RESULTS: Short (24 h) exposure of alveolar-like MDM (aMDM) to HDM suppressed 5-LOX expression and product formation, while triggering prostanoid (thromboxane and prostaglandin D2 and E2 ) production. This eicosanoid reprogramming was p38-dependent, but dectin-2-independent. HDM also induced proinflammatory cytokine production, but reduced granulocyte recruitment by aMDM. In contrast, high levels of cysteinyl leukotrienes (cysLTs) and 12-/15-LOX metabolites were produced in the airways during AAI or nematode infection in mice. CONCLUSION: Our findings show that a short exposure to allergens as well as ongoing type 2 immune responses are characterized by a fundamental reprogramming of the lipid mediator metabolism with macrophages representing particularly plastic responder cells. Targeting mediator reprogramming in airway macrophages may represent a viable approach to prevent pathogenic lipid mediator profiles in allergy or asthma.

Therapeutic potential of a phospholipase D1 inhibitory peptide fused with a cell-penetrating peptide as a novel anti-asthmatic drug in a Der f 2-induced airway inflammation model.

Asthma is a chronic lung disease that causes airflow obstruction due to airway inflammation. However, its therapeutics remain inadequate. We previously reported that phospholipase D1 (PLD1) is a key enzyme involved in the production of pro-inflammatory cytokines in airway inflammation induced by the house dust mite allergen Dermatophagoides farinae 2 (Der f 2). We also revealed that PLD1 is specifically inactivated by AP180 (assembly protein, 180 kDa) and identified the PLD1-specific binding motif (TVTSP) of AP180. Therefore, the aims of this study were to develop a novel anti-asthmatic agent that could suppress airway inflammation by inhibiting PLD1 and examine its acute and chronic toxicity. We designed TAT-TVTSP, a PLD1-inhibitory peptide fused with a cell-penetrating peptide (CPP) delivery system. TAT-TVTSP was efficiently delivered to bronchial epithelial cells and significantly reduced Der f 2-induced PLD activation and Interleukin 13 (IL-13) production. Intranasally administered TAT-TVTSP was also efficiently transferred to airway tissues and ameliorated airway inflammation in a Der f 2-induced allergic asthma mouse model. Moreover, we investigated the safety of TAT-TVTSP as a therapeutic agent through single- and repeated-dose toxicity studies in a mouse model. Taken together, these results indicated that a PLD1-inhibitory peptide fused with a cell-penetrating peptide may be useful for treating allergic inflammatory asthma induced by house dust mites (HDMs).