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Der F (der + f)
Selected AbstractsEffects of proline mutations in the major house dust mite allergen Der f 2 on IgE-binding and histamine-releasing activityFEBS JOURNAL, Issue 22 2000Toshiro Takai Der f 2 is the major group 2 allergen from house dust mite Dermatophagoides farinae and is composed of 129 amino-acid residues. Wild-type and six proline mutants of Der f 2 (P26A, P34A, P66A, P79A, P95A, and P99A) expressed in Escherichia coli were refolded and purified. Formations of intramolecular disulfide bonds in the purified proteins were confirmed correct. The apparent molecular masses analyzed by gel-filtration were 14,15 kDa. The IgE-binding capacity in the sera of seven mite-allergic patients, inhibitory activity for IgE-binding to immobilized wild-type Der f 2, and activity to stimulate peripheral blood basophils to release histamine in two volunteers were analyzed. P95A and P99A, which slightly differed from the wild-type Der f 2 in their CD spectrum, showed reduced IgE-binding, reduced inhibitory activity, and less histamine-releasing activity than the wild-type. P34A also showed reduced allergenicity. Considering that Pro95, Pro99 and Pro34 are closely located in loops at one end of the tertiary structure of Der f 2, we concluded that these loop regions included an IgE-binding site common to all tested patients. P66A showed reduced IgE-binding in two sera out of seven. P26A and P79A showed no reduced allergenicity. However, in immunoblot analysis after SDS/PAGE under reduced conditions, P79A showed no or markedly reduced IgE-binding while the other mutants showed IgE-binding corresponding to that in the assay using correctly refolded proteins. This suggests that Pro79 is involved in refolding of Der f 2. The findings in this study are important for the understanding of the antigenic structure of mite group 2 allergens and for manipulation of the allergens for specific immunotherapy. [source] Lipopolysaccharide binding of the mite allergen Der f 2GENES TO CELLS, Issue 9 2009Saori Ichikawa Lipid-binding properties and/or involvement with host defense are often found in allergen proteins, implying that these intrinsic biological functions likely contribute to the allergenicity of allergens. The group 2 major mite allergens, Der f 2 and Der p 2, show structural homology with MD-2, the lipopolysaccharide (LPS)-binding component of the Toll-like receptor (TLR) 4 signalling complex. Elucidation of the ligand-binding properties of group 2 mite allergens and identification of interaction sites by structural studies are important to explore the relationship between allergenicity and biological function. Here, we report a ligand-fishing approach in which His-tagged Der f 2 was incubated with sonicated stable isotope-labelled Escherichia coli as a potential ligand source, followed by isolation of Der f 2-bound material by a HisTrap column and NMR analysis. We found that Der f 2 binds to LPS with a nanomolar affinity and, using fluorescence and gel filtration assays that LPS binds to Der f 2 in a molar ratio of 1 : 1. We mapped the LPS-binding interface of Der f 2 by NMR perturbation studies, which suggested that LPS binds Der f 2 between the two large ,-sheets, similar to its binding to MD-2, the LPS-binding component of the innate immunity receptor TLR4. [source] Single nucleotide polymorphisms and haplotype of MD-1 gene associated with high serum IgE phenotype with mite-sensitive allergy in Taiwanese childrenINTERNATIONAL JOURNAL OF IMMUNOGENETICS, Issue 6 2007J. Y. Wang Summary MD-1 (myeloid differentiation 1; also known as Ly86, lymphocyte antigen 86), interacting with RP105, plays an important role in Toll-like receptor 4 (TLR4) signalling pathway. It has been suggested to be involved in the pathological mechanism of inflammation and atopic diseases. The purpose of this study was to investigate the genetic association between single nucleotide polymorphisms (SNPs) of MD-1 promoter and coding region and mite-sensitive allergy in Taiwanese children. We conducted a case-control study on 237 controls and 281 allergic patients sensitive to Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f) by genotyping 35 SNPs in MD-1 gene region. In the promoter region we identified three SNPs, rs1334710, rs4959389, and rs977785 that are associated with mite-sensitive allergy in Taiwanese children. The P -values ranged from 0.0150 to 0.009. The haplotypes including promoter region were also associated with mite-sensitive allergy. Our results suggested that MD-1 could be a susceptible gene for mite-sensitive allergy in Taiwanese children. [source] Major mite allergen Der f 1 concentration is reduced in buildings with improved energy performanceALLERGY, Issue 5 2010F. Spertini To cite this article: Spertini F, Berney M, Foradini F, Roulet C-A. Major mite allergen Der f 1 concentration is reduced in buildings with improved energy performance. Allergy 2010; 65: 623,629. Abstract Background:, Environmental conditions play a crucial role in mite growth, and optimal environmental control is key in the prevention of airway inflammation in chronic allergic rhinoconjunctivitis or asthma. Objective:, To evaluate the relationship between building energy performance and indoor mite allergen concentration in a cross-sectional study. Methods:, Major allergen concentration (Der f 1, Der p 1, mite group 2, Fel d 1 and Bla g 2) was determined by quantitative dot blot analysis from mattress and carpet dust samples in five buildings designed for low energy use (LEB) and in six control buildings (CB). Inhabitants had received 4 weeks prior to mite measurement a personal validated questionnaire related to the perceived state of health and comfort of living. Results:, Cumulative mite allergen concentration (with Der f 1 as the major contributor) was significantly lower in LEB as compared with CB both in mattresses and in carpets. In contrast, the two categories of buildings did not differ in Bla g 2 and Fel d 1 concentration, in the amount of dust and airborne mould collected. Whereas temperature was higher in LEB, relative humidity was significantly lower than in CB. Perceived overall comfort was better in LEB. Conclusions:, Major mite allergen Der f 1 preferentially accumulates in buildings not specifically designed for low energy use, reaching levels at risk for sensitization. We hypothesize that controlled mechanical ventilation present in all audited LEB may favour lower air humidity and hence lower mite growth and allergen concentration, while preserving optimal perceived comfort. [source] Characterization and comparison of commercially available mite extracts for in vivo diagnosisALLERGY, Issue 2 2010B. Brunetto To cite this article: Brunetto B, Tinghino R, Braschi MC, Antonicelli L, Pini C, Iacovacci P. Characterization and comparison of commercially available mite extracts for in vivo diagnosis. Allergy 2010; 65: 184,190. Abstract Background:, Assessment of sensitization by allergen-specific IgE testing and skin prick testing (SPT) are primary tools in routine clinical diagnosis of allergies. To perform a correct diagnosis, it is critical that the allergen reagent used contains an adequate amount of all relevant components. This study aimed at evaluating commercially available mite extracts for in vivo diagnosis from eight manufacturers. Methods:, Eight extracts from Dermatophagoides pteronyssinus and eight from Dermatophagoides farinae were analysed for total protein content by Bradford and for major allergen content by ELISA. SDS-PAGE, immunoblotting and SPT were also carried out. Results:, The protein amount ranged from 27.7 ,g/ml extract to 361.1 ,g/ml (D. pteronyssinus) and from 20.3 to 353.0 ,g/ml (D. farinae). In regards major allergen concentration, Der p 1 ranged from 9.6 to 36.2 ,g/ml, Der f 1 26.5,196.1 ,g/ml, mite group 2 0.7,31.7 ,g/ml in D. pteronyssinus and 1.3,10.4 ,g/ml in D. farinae. SDS-PAGE experiments showed that some components are poorly represented or absent in extracts from most manufacturers. Similar results were obtained by IgE-immunoblotting and SPT with 10 mite allergic patients confirmed a broad spectrum of reactivity of the extracts in the same subject. Conclusions:, Immunochemical analysis showed a heterogeneous amount of component/s among mite extracts from different manufacturers. These data were confirmed by in vivo testing, suggesting that, for some of the patient tested, the absence of relevant allergens could strongly affect the diagnosis. [source] Mite serine protease activates protease-activated receptor-2 and induces cytokine release in human keratinocytesALLERGY, Issue 9 2009T. Kato Background:, House dust mites produce serine and cysteine proteases. Mite-derived proteases have been suggested to be involved in the pathogenesis of allergies; however, whether mite-derived serine protease activity can stimulate keratinocytes remains unknown. Methods:, We examined the activation of primary human keratinocytes by serine protease-rich extract of whole mite culture and compared with that by recombinant group 1 allergens (rDer f 1 and rDer p 1), which exclusively exhibit cysteine protease activity. Results:, Protease activity of whole mite culture extract (WCE), rDer f 1 and rDer p 1 induced the release of IL-8 and granulocyte-macrophage colony-stimulating factor. Protease activity of WCEs induced a significant upregulation of their mRNA expression but rDer f 1 had much less effect. Protease activity of the WCE stimulated intracellular Ca2+ mobilization but rDer f 1 and rDer p 1 did not. The mobilization induced by agonists for the human protease-activated receptor (PAR)-2, an agonist peptide or trypsin, was diminished by pre-incubation of keratinocytes with WCE. rDer f 1 inefficiently cleaved a synthetic N-terminal peptide of PAR-2 at different sites from trypsin, but the resultant peptides did not stimulate the release of interleukin-8. Conclusions:, The results suggest that mite-derived serine protease activity may contribute to the pathogenesis of atopic dermatitis by activating keratinocytes via PAR-2 activation but cysteine protease activity of Der f 1 and Der p 1 acts via another mechanism. [source] Variation of dust endotoxin concentrations by location and time within homes of young childrenPEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 3 2010Dennis R. Ownby Ownby DR, Peterson EL, Williams LK, Zoratti EM, Wegienka GR, Woodcroft KJ, Joseph CLM, Johnson CC. Variation of dust endotoxin concentrations by location and time within homes of young children. Pediatr Allergy Immunol 2010: 21: 533,540. © 2010 John Wiley & Sons A/S Endotoxin may affect the development of allergic disease in childhood but little is known about endotoxin variation within homes. We sought to determine endotoxin concentration agreement within homes when five locations were each sampled twice 5 months apart. Endotoxin was measured using the recombinant Limulus factor C assay in dust samples from 585 homes of children enrolled in a prospective study and again in 335 homes 5 months later. The five locations sampled in each home were the child's bedroom floor, child's bed, mother's bedroom floor, mother's bed and living room floor. Concentrations of 4 allergens (Can f 1, Fel d 1, Der f 1 and Bla g 2) were also measured from the child's bedroom floor. In pair-wise comparisons, endotoxin concentrations in all locations within each home were significantly different from all other locations (p < 0.001) except for the child's and mother's bedroom floors (p = 0.272). Spearman correlations between endotoxin concentrations from the different locations were all statistically significant (p < 0.05) but of modest magnitude (r = 0.24,0.54). Similarly, correlations at each site over the 5 month observation interval were statistically significant but modest (r = 0.17,0.44). Pets and season of the year did not affect correlations, although correlations were lower if the floor was not carpeted. Endotoxin concentrations at all locations were minimally correlated with allergen concentrations in both negative and positive directions (r = ,0.12 to 0.12). We conclude that a single measurement of endotoxin from a home dust sample provides an imprecise estimate of dust endotoxin concentrations in other locations within the home and over a relatively short observation interval. [source] Crystallization and preliminary X-ray analysis of Der f 2, a potent allergen derived from the house dust mite (Dermatophagoides farinae)ACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2003Dana Roeber Although a number of allergens have been identified and isolated, the underlying molecular basis for the potent immune response is poorly understood. House dust mites (Dermatophagoides sp.) are ubiquitous contributors to atopy in developed countries. The rhinitis, dermatitis and asthma associated with allergic reactions to these arthropods are frequently caused by relatively small (125,129 amino acids) mite proteins of unknown biological function. Der,f,2, a major allergen from the mite D.,farinae, has been recombinantly expressed, characterized and crystallized. The crystals belong to the tetragonal space group I4122, with unit-cell parameters a = b = 95.2, c = 103.3,Å. An essentially complete (97.2%) data set has been collected to 2.4,Å at a synchrotron source. Attempts to solve the crystal structure of Der,f,2 by molecular replacement using the NMR coordinates for either Der,f,2 or Der,p,2 (the homologous protein from D.,pteronyssinus) failed, but preliminary searches using the crystalline Der p 2 atomic coordinates appear to be promising. [source] Rosmarinic acid in perilla extract inhibits allergic inflammation induced by mite allergen, in a mouse modelCLINICAL & EXPERIMENTAL ALLERGY, Issue 6 2004C. Sanbongi Summary Background Perilla and its constituent rosmarinic acid have been suggested to have anti-allergic activity. However, few studies have examined the effects on allergic asthma. Objective The purpose of this study was to evaluate the effect of oral administration of perilla leaf extract, which contains high amount of rosmarinic acid, on a murine model of allergic asthma induced by house dust mite allergen. Methods C3H/He mice were sensitized by intratracheal administration of Dermatophagoides farinae (Der f). Mice were orally treated with rosmarinic acid in perilla extract (PE) (1.5 mg/mouse/day). Results Der f challenge of sensitized mice elicited pulmonary eosinophilic inflammation, accompanied by an increase in lung expression of IL-4 and IL-5, and eotaxin. Daily treatment with rosmarinic acid in PE significantly prevented the increases in the numbers of eosinophils in bronchoalveolar lavage fluids and also in those around murine airways. Rosmarinic acid in PE treatment also inhibited the enhanced protein expression of IL-4 and IL-5, and eotaxin in the lungs of sensitized mice. Der f challenge also enhanced allergen-specific IgG1, which were also inhibited by rosmarinic acid in PE. Conclusion These results suggest that oral administration of perilla-derived rosmarinic acid is an effective intervention for allergic asthma, possibly through the amelioration of increases in cytokines, chemokines, and allergen-specific antibody. [source] Allergens, Der p 1, Der f 1, Fel d 1 and Can f 1, in newly bought mattresses for infantsCLINICAL & EXPERIMENTAL ALLERGY, Issue 11 2002R. De Boer Summary Background To avoid allergen exposure of newborn babies, the use of a new mattress for the baby bed may be recommended. However, it is not certain that new mattresses are always free of allergens. Objective In the present study the allergen content of new infant mattresses was investigated. Methods Dust samples were vacuumed from 90 new mattresses for infant beds bought in 50 different Dutch shops, and the concentrations of Der p 1, Der f 1, Fel d 1 and Can f 1 were determined by radioimmunoassays. Results Most mattresses contained some allergen and often the allergen concentrations were surprisingly high. Only 15 of the 90 mattresses contained no detectable amounts of any of the four allergens. The highest concentration found for each allergen was 3.1, 46.5, 20.2 and 95.7 µg/g of dust, respectively. However, the total amount of allergen in a mattress was still rather low because the new mattresses contained only modest amounts of dust. Baby mattresses more often contained an increased allergen load than the larger, standard-sized, infant mattresses. This may be caused by differences in manufacturing procedure. Also, mattresses that were sold without a plastic encasement more often contained an increased allergen load. Conclusions It is advisable to buy a mattress that is wrapped in plastic, but it may still contain a substantial amount of allergen. Thorough vacuuming of a newly bought mattress before it is installed on a child's bed, is also advisable. After instalment, regular vacuuming of the mattress and washing of the bed linen as well as measures to eliminate allergen reservoirs in other parts of the house are important, because our observations indicate that mattresses easily pick up allergens from the environment. [source] | |||||||||||||