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

ABSTRACT: 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.

SUBMITTER: Pascoe CD

PROVIDER: S-EPMC7347269 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:UnlabelledHIF-1? is a transcription factor that is activated during hypoxia and inflammation and is a key regulator of angiogenesis in vivo. During the development of asthma, peribronchial angiogenesis is induced in response to aeroallergens and is thought to be an important feature of sustained chronic allergic inflammation. Recently, elevated HIF-1? levels have been demonstrated in both the lung tissue and bronchoalveolar lavage of allergic patients, respectively. Therefore, we investigated the role of HIF-1? on the development of angiogenesis and inflammation following acute and chronic allergen exposure. Our data shows that intranasal exposure to house dust mite (HDM) increases the expression of HIF-1? in the lung, whilst reducing the expression of the HIF-1? negative regulators, PHD1 and PHD3. Blockade of HIF-1? in vivo, significantly decreased allergic inflammation and eosinophilia induced by allergen, due to a reduction in the levels of IL-5 and Eotaxin-2. Importantly, HIF-1? blockade significantly decreased levels of VEGF-A and CXCL1 in the lungs, which in turn led to a profound decrease in the recruitment of endothelial progenitor cells and a reduction of peribronchial angiogenesis. Furthermore, HDM or IL-4 treatment of primary lung macrophages resulted in significant production of both VEGF-A and CXCL1; inhibition of HIF-1? activity abrogated the production of these factors via an up-regulation of PHD1 and PHD3. These findings suggest that novel strategies to reduce the expression and activation of HIF-1? in lung macrophages may be used to attenuate allergen-induced airway inflammation and angiogenesis through the modulation of VEGF-A and CXCL1 expression.Clinical relevanceThis study provides new insights into the role of HIF-1? in the development of peribronchial angiogenesis and inflammation in a murine model of allergic airway disease. These findings indicate that strategies to reduce activation of macrophage derived HIF-1? may be used as a target to improve asthma pathology.

Project description:Evidence regarding asthma's impact on children's daily lives is limited. This prospective and cross-sectional, observational, multicenter study assessed school/work and activity impairment in children and adolescents with allergic asthma and their caregivers and allergen immunotherapy (AIT) effects. Included patients were schooled children and adolescents (5 to 17 years) with allergic asthma due to house dust mites (HDM). Impairment of school/work (i.e., absenteeism and presenteeism) and activity was measured in patients and their caregivers using the Work Productivity Impairment Questionnaire plus Classroom Impairment Questions: Allergy Specific (WPAI + CIQ:AS). HDM allergic patients with school impairment received subcutaneous AIT with a MicroCrystalline Tyrosine-associated allergoid. WPAI + CIQ:AS and effectiveness variables were compared between baseline and 1-year post-AIT. Of the 113 patients included, 59 (52.2%) and 51 (45.1%) showed school and activity impairment, respectively, missing a mean (SD) of 37.6 (24.4) % and 42.6 (25.6) % of school and activity time, respectively. Twenty-six (23%) caregivers reported activity impairment and, of the 79 (69.9%) employed, 30 (38%) reported work impairment. Of the 65 patients with school/activities impairment, 41 (63.1%) received AIT, of which 21 (51.2%) completed 1 year of treatment. Effectiveness variables and WPAI + CIQ:AS significantly improved: Mean (SD) school impairment decreased from 39.7 (26.7) to 2.1 (7.1) % (p < 0.001) and activity impairment from 46.2 (34.6) to 1.4 (3.6) % (p < 0.001).Conclusion: Allergic asthma due to HDMs results in school/work and activity impairment in children and adolescents and their caregivers. One year of AIT provided clinical benefits and reduced school and activity impairment. What is Known: • Allergic asthma impairs children's school performance and daily activities. • Allergen immunotherapy modifies allergic disease course and ameliorates its symptoms. What is New: • Asthma symptoms due to allergy to house dust mites impair children's school attendance and productivity and daily activity and their caregivers' work performance and daily lives. • Allergen immunotherapy with a house dust mite MicroCrystalline Tyrosine (MCT)-associated allergoid seems to provide clinical benefits, associated with decreased school and activity impairment, supporting it as an effective treatment option.

Project description:BackgroundHouse dust mites (HDMs) such as Dermatophagoides farinae and D. pteronyssinus represent major causes of perennial allergy. HDM proteomes are currently poorly characterized, with information mostly restricted to allergens. As of today, 33 distinct allergen groups have been identified for these 2 mite species, with groups 1 and 2 established as major allergens. Given the multiplicity of IgE-reactive mite proteins, potential additional allergens have likely been overlooked.ObjectiveTo perform a comprehensive characterization of the transcriptomes, proteomes and allergomes of D. farinae and D. pteronyssinus in order to identify novel allergens.MethodsTranscriptomes were analyzed by RNA sequencing and de novo assembly. Comprehensive mass spectrometry-based analyses proteomes were combined with two-dimensional IgE reactivity profiling.ResultsTranscripts from D. farinae and D. pteronyssinus were assembled, translated into protein sequences and used to populate derived sequence databases in order to inform immunoproteomic analyses. A total of 527 and 157 proteins were identified by bottom-up MS analyses in aqueous extracts from purified HDM bodies and fecal pellets, respectively. Based on high sequence similarities (>71% identity), we also identified 2 partial and 11 complete putative sequences of currently undisclosed D. pteronyssinus counterparts of D. farinae registered allergens. Immunoprofiling on 2D-gels revealed the presence of unknown 23 kDa IgE reactive proteins in both species. Following expression of non-glycosylated recombinant forms of these molecules, we confirm that these new allergens react with serum IgEs from 42% (8/19) of HDM-allergic individuals.ConclusionsUsing combined transcriptome and immunoproteome approaches, we provide a comprehensive characterization of D. farinae and D. pteronyssinus allergomes. We expanded the known allergen repertoire for D. pteronyssinus and identified two novel HDM allergens, now officially referred by the International Union of Immunological Societies (IUIS) Nomenclature Subcommittee as Der f 36 and Der p 36.

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

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