Systematic Characterization of the Group 2 House Dust Mite Allergen in Dermatophagoides microceras

BackgroundAllergic asthma, a chronic airway inflammatory disease, is a critical public health problem. Indoor house dust mites (HDMs) could cause allergic asthma. The prevalence of sensitization to Dermatophagoides microceras (Der m) was approximately 80% and is related to the immunoglobulin E crossing-reactivity of mites belonging to the same genus, Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farina (Der f). However, studies on Der m are scant.MethodsWe used integrated OMICs approaches to identify and characterize the group 2 mite allergen-like protein in Der m (Der m 2). We established a Der m 2-induced allergic asthma mouse model and treated the mice with a fungal immunomodulatory protein (FIP-fve) isolated from Flammulina veluptipes to evaluate the allergenicity of Der m 2 and the immunomodulatory effects of FIP-fve.ResultsBy performing de novo draft genome assembly and comparative genome analysis, we identified the putative 144-amino acid Der m 2 in silico and further confirmed its existence through liquid chromatography–tandem mass spectrometry. Der m 2 is a lipopolysaccharides (LPS)-binding protein. Thus, we examined the LPS-binding activity of recombinant Der m 2 by performing molecular docking analysis, co-immunoprecipitation (Co-IP), and a pull-down assay. Der m 2 elicited the production of pro-inflammatory cytokines, interleukin (IL)-6, and IL-8 in BEAS-2B cells, a human bronchial epithelial cell line, and induced airway hyperresponsiveness in mice. Furthermore, in mice sensitized with Der m 2, the administration of FIP-fve in either the earlier stage or the late stage, FIP-fve alleviated allergic asthma by moderating airway inflammation and remodeling.ConclusionsDer m 2 induced inflammatory responses in cell and mouse models. FIP-fve alleviated inflammation in Der m 2-induced asthma in mice by exerting an immunomodulatory effect.

Critical Involvement of CD44 in T Helper Type 2 Cell-Mediated Eosinophilic Airway Inflammation in a Mouse Model of Acute Asthma

Interactions between CD44 and hyaluronan (HA) are crucial for recruiting leukocytes to inflamed tissues. This review summarizes findings from our studies of the roles of CD44-HA interactions in leukocyte trafficking, with a particular focus on airway T helper type 2 (Th2) cells in mouse models of acute asthma. In a mite allergen-induced model of acute asthma, intraperitoneal injection of anti-CD44 monoclonal antibodies blocked lymphocytes and eosinophils from accumulating in the lung, and suppressed both the antigen-induced increase in Th2 cytokines in the bronchoalveolar lavage fluid (BALF) and airway hyperresponsiveness (AHR). CD44 deficiency was associated with decreased mite allergen-induced Th2 cell-mediated airway inflammation and AHR in sensitized mice. Asthmatic responses to antigen-sensitized splenic CD4+ T cells transferred from CD44-deficient mice were weaker than in wild-type mice. Administration of anti-CD44 monoclonal antibodies preferentially suppressed the airway accumulation of antigen-specific Th2 cells induced by antigen challenge, without affecting Th1 and Th17 cells. Increased HA-binding ability of CD44 and expression of Neu1 sialidase were observed on antigen-specific Th2 cells compared with antigen-specific Th1 and Th17 cells. Finally, in a mouse model of acute asthma, neuraminidase 1-deficient SM/J mice exhibited a lower Th2 cytokine concentration and a lower absolute Th2 cell number in the BALF, as well as an attenuated AHR. Our findings indicate that CD44 critically contributes to the antigen challenge-induced airway accumulation of antigen-specific Th2 cells, without affecting Th1 and Th17 cells, in mice. Furthermore, neuraminidase 1 activity is necessary for the interaction between HA and CD44, and Th2 cell-mediated airway inflammation.

Efficacy of mite allergen immunotherapy in allergic rhinitis and the immune synergistic effect on cross-allergens

Aim: To compare the efficacy of single- and double-species mite allergen immunotherapy. Materials and methods: An open, pseudo-randomized, controlled study was conducted (n = 125 allergic rhinitis patients). The primary end point involved the visual analogue scale. Secondary end points included a basophil activation test and serum specific IgE and IgG4 assays. Results: Visual analogue scale analysis indicated considerable reductions in both groups. Both treatments improved quality of life and induced sIgG4 antibody production. Basophil activation and serum IgE inhibition were not evident in either treatment. Neither treatment displayed an early stage immune synergistic effect on cross-allergens. Conclusions: Both treatments were effective against allergic rhinitis, and statistical differences were not observed. Future studies may require long-term, large-scale research.

Analytical study of inflammatory cytokines and immunoglobulin expression following dust mite allergen exposure in pregnant mice

Background Allergen tolerability due to allergic immune reactions could be transferred through the placenta from maternal to fetal circulation. Hence, a further investigation regarding the tolerability following mite allergen exposures is desirable. Objective To evaluate various doses of mite allergens and cytokines associated with Th1, Th2, and Treg cells with regards to possible allergic tolerance in neonatal mice. Methods This study used an experimental design with a post-test only control group, to assess the effect of mite allergens on pregnant BALB/C mice and their newborns. In this study female BALB/C mice aged 10 weeks were mated with male mice, then pregnant BALB/C mice were exposed to allergens at 4 weeks gestation. During pregnancy, pregnant females’ blood specimens were taken to measure cytokines and immunoglobulins. Meanwhile, neonatal blood specimens were taken at 2 weeks postnatally to measure cytokines and immunoglobulins. Blood specimens from pregnant BALB/C mice and their newborns were evaluated using ELISA kits for the following cytokines: interleukin (IL)-2, interferon (IFN)-γ, interleukin (IL)-4, IL-5, IL-10, TGF-β1, as well as immunoglobulins (Ig)G-1, IgG-2a, IgG-2b, IgG3 subclass, IgM, IgA, and IgE. The case group was the group that received high and low doses of exposure, while the control group did not get exposure. Results In response to low dose mite allergen exposure, there were significant increases of IL-2, IFN-y, and IL-4, IL-5, and TGF-β1 in mothers and neonates. Pregnant mices that received high doses of allergens, however, had significant increases in IL-5 and TGF-B1; results were likewise for their offspring. Mothers and neonates, had significantly increased expression of IgG subclasses after a low dose of dust mite allergen. Following a ten-fold increase in allergen dose, the mothers showed significant increases in IgA, IgM, IgE, and IgG subclasses, whereas in neonatal mice, those immunoglobulin levels were not significantly different from control mice. Conclusion Exposure to mite allergens can trigger regulatory functions of Th1, Th2, and Tregs cells to activate their cytokines, except IL-10. The regulatory function of Tregs is dominated by TGFβ in maternal and neonatal mice, at low and high doses. Th1 cytokines express cytokines during exposure only to low-dose allergens and Th2 cells regulate IL-5 levels to both low- and high-dose allergens.

Screening for antibodies against the sheep scab mite (Psoroptes ovis) Pso o 2 antigen in experimentally infested Swifter sheep may fail to identify affected animals

Sheep scab, caused by Psoroptes ovis mites, represents a significant threat to sheep health and welfare. Infestations are diagnosed by parasite identification in skin scrapings, and more recently with a commercial ELISA against serum antibodies to the Pso o 2 mite allergen. However, little is known about the performance of the ELISA in non-UK sheep populations. In this study, six Swifter sheep were experimentally infested with P. ovis. Lesion sizes were monitored and serum IgG against Pso o 2 and the novel Pso-EIP-1 antigens were measured by ELISA. Although all sheep showed signs of infestation, serum from two animals failed to react with Pso o 2. However, they did react to Pso-EIP-1. This indicates that cases of sheep scab in (Swifter) sheep may remain undetected using the Pso o 2 ELISA, which may have implications for routine screening of non- UK sheep breeds.

Benzo[a]pyrene aggravates atopic dermatitis-like skin lesions in mice

Background: Benzo[a]pyrene (BaP) affects the immune system and causes mutagenic and carcinogenic effects. Purpose: We aimed to evaluate the effects of systemic exposure to BaP on mite allergen–induced atopic dermatitis (AD)–like skin lesions in mice. Methods: Mite allergen ( Dermatophagoides pteronyssinus; Dp) was injected intradermally into the right ears of NC/Nga male mice on eight occasions every 2–3 days. Benzo[a]pyrene was administered intraperitoneally in the equivalent doses of 0, 2, 20, 200, or 2000 μg/kg/day, once a week on four occasions. Results: AD-like skin inflammation related to mite allergen worsened by BaP exposure at 2, 20 µg/kg/day doses; this was in parallel with eosinophil and mast cell infiltration and mast cell degranulation. A trend was also observed toward increased proinflammatory molecule expression, including macrophage inflammatory protein-1 alpha, interleukin (IL)-4, IL-13, and IL-18, in the ear tissue. However, 200 or 2000 µg/kg/day BaP attenuated the enhancing effects. In the regional lymph nodes, 2 µg/kg/day BaP with Dp enhanced antigen-presenting cell and T cell activation compared with Dp alone. Conclusions: This suggests that BaP exposure can aggravate Dp-induced AD-like skin lesions through TH2-biased responses in the inflamed sites and the activation of regional lymph nodes. Therefore, BaP may be responsible for the recent increase in AD incidence.