Cloning, bioinformatics analysis, and expression of the dust mite allergen Der f 5 of Dermatophagoides farinae

Immunobiological properties and structure analysis of group 13 allergen from Blomia tropicalis and its IgE-mediated cross-reactivity

Blomia tropicalis is an important species of allergenic mite. Structurally related cross-reactive allergens are involved in pathogenesis of clinical symptoms. The present study focused on recombinant allergen rBlo t 13 from B. tropicalis, including investigation of its structure, immunological properties, IgE-mediated cross-reactivity. In this work, the prokaryotic expression plasmids pET-28(a)-Blo t 13, pET-28(a)-Der f 13, and pET-28(a)-Tyr p 13 were constructed, transformed into E. coli Rosetta (DE3) pLysS, and purified by nickel affinity chromatography, respectively. By using ELISA, the IgE-binding rates were detected for rBlo t 13 and its epitope peptides, as well as the cross-reactivity among rBlo t 13, rDer f 13, and rTyr p 13. The tertiary structure of rBlo t 13 was resolved using X-ray diffraction at 2.0 Å resolution. Using IgE-ELISA, the IgE binding rate of rBlo t 13 was 60 % with Blomia tropicalis-positive sera. In the experiments of ELISA for cross-reactivity with rBlo t 13 on solid phase, the inhibition rates were 65 %, 57 % and 63 % for rBlo t 13, rDer f 13, and rTyr p 13, respectively. The structure of Blo t 13 protein contains a β-barrel structure which is composed of 10 β strands and has 2 α helices at the end of the barrel. Comparison of the tertiary structures of rBlo t 13, rDer f 13, and rTyr p 13 revealed that the β-barrel structure is highly conserved, consistent with the alignment of amino acid sequences. We obtained the recombinant protein rBlo t 13, demonstrated its cross-reactivity with Der f 13 and Tyr p 13 due to their structural similarity.

Securinega suffruticosa extract alleviates atopy-like lesions in NC/Nga mice via inhibition of the JAK1-STAT1/3 pathway

Securinega suffruticosa (SS) has well-known antioxidant, anti-vascular inflammation, and anti-bone resorption effects; however, the effects of SS in atopic dermatitis (AD) remain unknown. We examined the effects of SS on AD via application of Dermatophagoides farinae extract (DfE) to the ears and skin of NC/Nga mice. As a result of SS administration, DfE-induced AD mice had reduced ear thickness, epidermal thickness, scratching behavior, and transepidermal water loss. The serum levels of immunoglobulin E and thymic interstitial lymphopoietin (TSLP) were reduced by SS application. SS decreased mast cell and eosinophil recruitment to skin lesions. Phosphorylation of signal transducer and activation of transcription (STAT)1, STAT3, and Janus kinase 1 were reduced in the skin tissue of SS-administered mice, and downregulated filaggrin was restored. SS reduced the levels of interleukin-6, regulated on activation, normal T cell expressed and secreted chemokine, and TSLP in interferon-γ/tumor necrosis factor-α-induced keratinocytes. The main components of SS were rutin and geraniin. These study results indicated that SS extract attenuated AD and has potential as a therapeutic natural product candidate for AD.

Chinese Guideline on Allergen Immunotherapy for Allergic Rhinitis: The 2022 Update

In the last few decades, there has been a progressive increase in the prevalence of allergic rhinitis (AR) in China, where it now affects approximately 250 million people. AR prevention and treatment include allergen avoidance, pharmacotherapy, allergen immunotherapy (AIT), and patient education, among which AIT is the only curative intervention. AIT targets the disease etiology and may potentially modify the immune system as well as induce allergen-specific immune tolerance in patients with AR. In 2017, a team of experts from the Chinese Society of Allergy (CSA) and the Chinese Allergic Rhinitis Collaborative Research Group (C2AR2G) produced the first English version of Chinese AIT guidelines for AR. Since then, there has been considerable progress in basic research of and clinical practice for AIT, especially regarding the role of follicular regulatory T (TFR) cells in the pathogenesis of AR and the use of allergen-specific immunoglobulin E (sIgE) in nasal secretions for the diagnosis of AR. Additionally, potential biomarkers, including TFR cells, sIgG4, and sIgE, have been used to monitor the incidence and progression of AR. Moreover, there has been a novel understanding of AIT during the coronavirus disease 2019 pandemic. Hence, there was an urgent need to update the AIT guideline for AR by a team of experts from CSA and C2AR2G. This document aims to serve as professional reference material on AIT for AR treatment in China, thus improving the development of AIT across the world.

Alpinia officinarum water extract inhibits the atopic dermatitis-like responses in NC/Nga mice by regulation of inflammatory chemokine production

Alpinia officinarum (AO) has been traditionally used in Asia as an herbal medicine to treat inflammatory and internal diseases. However, the therapeutic effect of AO on atopic dermatitis (AD) is unclear. Therefore, we examined whether Alpinia officinarum water extract (AOWex) affects AD in vivo and in vitro. Oral administration of AOWex to NC/Nga mice with Dermatophagoies farina extract (DfE)-induced AD-like symptoms significantly reduced the severity of clinical dermatitis, epidermal thickness, and mast cell infiltration into the skin and ear tissue. Decreased total serum IgE, macrophage-derived chemokine (MDC), and regulated on activation, normal T-cell expressed and secreted (RANTES) levels were observed in DfE-induced NC/Nga mice in the AOWex-treated group. These effects were confirmed in vitro using HaCaT cells. Treatment with AOWex inhibited the expression of proinflammatory chemokines such as MDC, RANTES, IP-10 and I-TAC in interferon-γ and tumor necrosis factor-α-stimulated HaCaT cells. The anti-inflammatory effects of AOWex were due to its inhibitory action on MAPK phosphorylation (ERK and JNK), NF-κB, and STAT1. Furthermore, galangin, protocatechuic acid, and epicatechin from AOWex were identified as candidate anti-AD compounds. These results suggest that AOWex exerts therapeutic effects against AD by alleviating AD-like skin lesions, suppressing inflammatory mediators, and inhibiting major signaling molecules.

Anti-Inflammatory Effects of Ellagic Acid on Keratinocytes via MAPK and STAT Pathways

Atopic dermatitis (AD) is a chronic inflammatory skin disease that is characterized by an impaired skin barrier and intense itchiness, which decreases the individual’s quality of life. No fully effective therapeutic agents have prevailed for AD due to an insufficient grasp of the complex etiology. Ellagic acid (EA), a natural compound, has anti-inflammatory properties in chronic diseases. The effects of EA on AD have not yet been explored. The present study investigated the effects of EA on TNF-α/IFN-γ-stimulated HaCaT keratinocytes and house dust mite-induced AD-like skin lesions in NC/Nga mice. Treatment with EA suppressed inflammatory responses in keratinocytes by regulating critical inflammatory signaling pathways, such as mitogen-activated protein kinases and signal transducers and activators of transcription. In vivo studies using a DfE-induced AD mouse model showed the effects of EA administration through ameliorated skin lesions via decremented histological inflammatory reactions. These results suggest that EA could be a potential therapeutic alternative for the treatment of AD by inhibiting inflammatory signaling pathways.

Mapping Mimotopes for House Dust Mite Allergen Der f 7 Using a Specific Monoclonal Antibody

BACKGROUND

The dust mite Dermatophagoides farinae is a common worldwide cause of indoor allergies induced by its proteins, including the mid-tier allergen Der f 7.

OBJECTIVE

To identify conformational epitopes in Der f 7 using mimotope mapping and computational modelling.

METHODS

Here, we used standard hybridoma technology to generate 3 new monoclonal antibodies against Der f 7 and performed mimotope mapping by probing a random peptide phage display library. Computational tools, including Minox and the DiscoTope-2.0 Server were used to assess the structure and potential position of antigenic residues within Der f 7.

RESULTS

Thirteen mimotopes sharing the common sequence --XX[LST]P[-E][LI]MLPLR[-S]- were identified. Further, computationally-predicted conformational epitopes were found at residues 1-7, 10, 27, 76-81, 92, and 130-133 of Der f 7, and the key amino acids for these epitopes were deduced to be 2P, 3I, 10E, 27E, 78E, 79E, 81I, 130S, and 132E based on the common mimotope sequence.

CONCLUSION

We identified Der f 7 peptide mimotopes that may model binding sites for blocking antibodies. These may guide the development of immunotherapy for individuals with hypersensitivity to Der f 7.

Cross-Reactivity between Major IgE Epitopes of Family 5 Allergens from Dermatophagoides pteronyssinus and Blomia tropicalis

BACKGROUND

The aim of this work was to understand the molecular features that trigger the cross-reactivity observed between Der p 5 from Dermatophagoides pteronyssinus, Blo t 5 from Blomia tropicalis, and Der f 5 from D. farinae.

METHODS

We collected serum from 60 house dust mite (HDM)-allergic patients residing in the Dellys area of Boumerdès province in northern Algeria. The presence of specific IgE to Der p 5, Der f 5, and Blo t 5 was analyzed. We performed in silico analysis of the structure of the different allergens in order to identify epitopes that can elicit the cross-reactivity of the sera. Synthetic peptides corresponding to the linear epitope sequence of Der p 5, Der f 5, and Blo t 5 were used to evaluate its implication in the cross-reactivity between the allergens. We also modified the sequence of the conformational epitope of Der p 5 by site-directed mutagenesis to mimic Blo t 5.

RESULTS

Several sera of patients allergic to HDM contained specific IgE antibodies to Der p 5 and Blo t 5. We demonstrated that the linear epitope of Der p 5 and Blo t 5 is not involved in the cross-reactivity of the sera. Furthermore, mutations introduced in the sequence of Der p 5 to mimic Blo t 5 could not modulate the cross-reactivity between them.

CONCLUSIONS

The major linear IgE epitopes of Der p 5 and Blo t 5 are involved in species-specific recognition. Our results may be useful for the development of a hypoallergenic vaccine against HDM group 5 allergens.

Transcriptomics-Based Identification of Aquaporin Diversity in the House Dust Mite Dermatophagoides farinae (Acariformes: Pyroglyphidae)

Aquaporin water channel proteins are highly conserved across many diverse species. Some evidence indicates that aquaporins in insects may contribute to insect-related mammalian diseases and inflammation, and thus these proteins may represent viable therapeutic targets. Here, we used RNA sequencing and bioinformatics to identify putative aquaporins from the house dust mite, Dermatophagoides farinae. Six putative aquaporins were identified based on sequence similarity with aquaporins from other species. These putative aquaporins, deposited in GenBank and named DerfAQP1-4 (KY231248, KY231249, KY231250, and KY231251, respectively), DerfAQP5.01, and DerfAQP5.02 (KY231252 and KY231253), were successfully cloned into a bacterial plasmid. The identification of full-length aquaporin sequences from D. farinae provides a foundation for future molecular and biochemical studies of these proteins in D. farinae and related species.

Chinese Guideline on allergen immunotherapy for allergic rhinitis

The present document is based on a consensus reached by a panel of experts from Chinese Society of Allergy (CSA) and Chinese Allergic Rhinitis Collaborative Research Group (C2AR2G). Allergen immunotherapy (AIT), has increasingly been used as a treatment for allergic rhinitis (AR) globally, as it has been shown to provide a long-term effect in improving nasal and ocular symptoms, reducing medication need, and improving quality of life. AIT is currently the only curative intervention that can potentially modify the immune system in individuals suffering from AR and prevent the development of new sensitization and the progression of disease from AR to asthma. Although the use of AIT is becoming more acceptable in China, to date no AR immunotherapy guideline from China is available for use by the international community. This document has thus been produced and covers the main aspects of AIT undertaken in China; including selection of patients for AIT, the allergen extracts available on the Chinese market, schedules and doses of allergen employed in different routes of AIT, assessment of effect and safety, patients' administration and follow-up, and management of adverse reactions. The Chinese guideline for AR immunotherapy will thus serve as a reference point by doctors, healthcare professionals and organizations involved in the AIT of AR in China. Moreover, this guideline will serve as a source of information for the international community on AIT treatment strategies employed in China.

Dermatophagoides farinae allergen Der f 9: Cloning, expression, purification, characterization and IgE-binding in children with atopic asthma

BACKGROUND

The house dust mite species Dermatophagoides farinae releases allergens that cause allergies and asthma worldwide. This study sought to clone and express the full-length cDNA encoding the group 9 allergen of D. farinae (Der f 9).

METHODS

The published sequence of Der f 9 was used to design primers for RT-PCR and RACE to obtain the full-length cDNA encoding Der f 9. After removal of signal peptide sequence, Der f 9 was then sub-cloned into plasmid pET-28b (+), and the plasmid was transformed into Escherichia coli BL21 (DE3) cells for expression. The recombinant protein was purified by Nickel affinity chromatography, identified by SDS-PAGE, Western blotting, dot blotting, and MALDI-TOF, and tested by ELISA for IgE reactivity with sera from children with asthma. Bioinformatics analyses were used to identify features of Der f 9.

RESULTS

By RT-PCR, 3'-RACE, and 5'-RACE, the full-length sequence of Der f 9 was generated, which was confirmed by nucleotide sequencing. The mature Der f 9 was expressed successfully in E. coli, which was identified by SDS-PAGE. The recombinant allergen was purified by chromatography and confirmed by SDS-PAGE, Western blotting, dot blotting, and MALDI-TOF. Sera from 56.7% (17/30) of mite-allergic patients reacted with the purified recombinant Der f 9.

CONCLUSIONS

The successful production of recombinant Der f 9 protein revealed the importance of Der f 9 in mite allergy, and provides a foundation for further study of this allergen in diagnosis and treatment of symptoms. Pediatr Pulmonol. 2017;52:282-292. © 2016 Wiley Periodicals, Inc.

Transcriptomic/proteomic identification of allergens in the mite Tyrophagus putrescentiae

While a number of allergens from house dust mites have been described, much remains to be discovered about allergens from storage mites. Here, next-generation sequencing was combined with MS/MS shotgun proteomics to identify proteins, especially potential allergens from Tyrophagus putrescentiae, commonly found in stored food products, especially flour. cDNAs of suspected allergens were cloned and expressed from bacterial cells, and recombinant allergens were tested for binding to IgE in sera from T. putrescentiae-sensitive patients. These analyses identified three previously uncharacterized allergens, Tyr p 28, Tyr p 35, and Tyr p 36, which have been officially assigned by the WHO/IUIS Allergen Nomenclature Sub-committee. Recombinant proteins rTyr p 28, rTyr p 35, and rTyr p 36 bound with 47.1%, 82.4%, and 70.6% of T. putrescentiae-sensitive sera. We provide here a new method to identify allergens by the combination of transcriptomic and proteomic approaches.

Sequential epitopes of Dermatophagoides farinae allergens identified using peptide microarray-based immunoassay

House dust mites produce over 30 proteins proposed to induce immunoglobulin E (IgE) antibody production in patients. Continued identification of IgE-binding epitopes of these allergens is critical to advancing diagnosis and treatment of allergic disease. To identify possible sequential IgE-binding epitopes of the major- and mid-potency allergens from the house dust mite Dermatophagoides farinae by peptide microarray-based immunoassay, nucleotide sequences of D. farinae allergens (Der f) 1, 2, 4, 5, and 7 were used to generate overlapping peptides covering the full protein sequences minus signal peptides. Short peptides were printed onto microarray chips. Because asthma occurs as a symptom of mite allergy more commonly among children than adults, the peptide chips were exposed to sera pooled from six serum-positive pediatric patients with D. farinae hypersensitivity and six serum-negative control children for screening sequential IgE-binding epitopes by IgE immunolabeling. Higher-than-average immunolabel signal intensity was observed for 21 short peptides in the serum-positive group (P < 0.01). Due to sequence overlap, these 21 signals represented four fragments of Der f 1 (amino acid positions 46-53, 71-78, 99-110, 179-186), three fragments of Der f 2 (15-22, 80-89, 106-113), six fragments of Der f 4 (69-82, 107-116, 225-232, 261-268, 355-365, 483-496), one fragment of Der f 5 (102-109), and three fragments of Der f 7 (32-39, 52-64, 100-107). These findings not only demonstrate the utility of a peptide microarray immunoassay in identifying epitopes for these allergens, but also provide a foundation for future exploration of specific immunotherapies. © 2016 IUBMB Life, 68(10):792-798, 2016.

Dust mite allergen Der f 4: Expression, characterization, and IgE binding in pediatric asthma

BACKGROUND

House dust mite hypersensitivity affects millions of people worldwide, and although many allergens produced by house dust mite species have been identified, some of the less potent allergens remain to be studied.

METHODS

The full-length cDNA encoding the group 4 allergen of the house dust mite species Dermatophagoides farinae (Der f 4) was generated through degenerate primer-based PCR, 5' RACE, and 3' RACE, and the cDNA fragment was cloned into an expression vector for nucleotide sequencing. Following codon optimization and removal of the signal peptide sequence, the mature gene fragment was subcloned into pET-28b (+) and transfected into E. coli BL21 cells for expression. The recombinant protein was purified by nickel affinity chromatography, identified by SDS-PAGE, Western blotting, and MALDI-TOF, and tested by ELISA for IgE reactivity with sera from individuals with asthma. Bioinformatics analyses were used to identify features of Der f 4.

RESULTS

SDS-PAGE and Western blotting of the codon-optimized expression product showed a specific band. The mature recombinant Der f 4 was characterized as a stable and hydrophilic 57.9-kDa protein, and its secondary structure comprised alpha helix (25.3%), extended strand (22.51%), and random coils (52.19%). The structure of the recombinant protein was consistent with that of α-amylase. Among 27 pediatric asthma patients, 40.74% exhibited reactivity to rDer f 4 by ELISA.

CONCLUSIONS

This initial cloning and characterization of the Der f 4 allergen serves as a foundation for future studies into the clinical importance and application of this protein for house dust mite allergy.

The Dermatophagoides farinae group 22 allergen: cloning and expression in Escherichia coli

BACKGROUND

Dermatophagoides farinae (Hughes) (Acari: Pyroglyphidae) and other domestic mites produce allergens that affect people worldwide. Here, the complementary DNA (cDNA) coding for group 22 allergen of D. farinae (Der f 22) from China was cloned, sequenced, and expressed successfully.

METHODS

The cDNA encoding Der f 22 was synthesized by reverse transcription polymerase chain reaction (RT-PCR), then ligated to the pCold-TF for expression in Escherichia coli BL21 cells. The purified recombinant fusion protein was identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Western-blotting, and tandem matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF/TOF).

RESULTS

The full-length cDNA comprised 468 nucleotides and was 99.57% (466/468) identical with the reference sequence (GenBank: DQ643992). After the plasmid pCold-TF-Der f 22 was transformed into E. coli BL21 and expressed with the induction of IPTG, SDS-PAGE showed a specific band for the recombinant fusion protein. The recombinant fusion protein, which was purified by chromatography, bound with a His-tagged antibody by Western blotting. MALDI-TOF/TOF mass spectrometry revealed that the structure of the recombinant protein was identical to the predicted Der f 22 structure. The hydrophilic protein contains a signal peptide of 20 amino acids, and the mature Der f 22 consists of 135 amino acid residues with a molecular weight of 14.7 kDa and theoretical isoelectric points (pI) of 6.38. Its secondary structure comprises an alpha helix (38.5%), beta-sheet (45.9%), random coils (11.85%), and beta-turns (11.1%).

CONCLUSION

This work represents the first reported full-length sequence and successful cloning of Der f 22 from D. farinae in China; bioinformatics analysis can be used to further study the allergenicity and clinical utility of the recombinant Der f 22.

Expression, cloning, and IgE-binding of the full-length dust mite allergen Der f 8

Dermatophagoides farinae, a domestic mite species, produces some of the most potent allergens that contribute to allergy in China and worldwide. We sought to clone and express the group 8 allergen of D. farinae (Der f 8) to investigate its IgE-binding reactivity. The full-length cDNA encoding Der f 8 was generated by using RT-PCR and 5' RACE, cloned into pCold-TF expression vector, confirmed by nucleotide sequencing, sub-cloned into pET-28b (+), and transfected into E. coli BL21 cells for expression. After purification by nickel affinity chromatography and identified by SDS-PAGE, the recombinant Der f 8 bound with sera from 40.9 % (9/22) of mite-allergic patients according to ELISA testing. Analysis of the recombinant DNA sequence revealed a 231 amino acid open reading frame encoding a protein with a derived molecular mass of 26.4 kDa and an isoelectric point of 6.84. The deduced amino acid sequence has nine phosphorylation sites, displaying strong homology with glutathione S-transferase, and its secondary structure comprises alpha helix (45.5 %), extended strand (11.3 %), and random coils (43.3 %). BLAST through the National Center for Biotechnology Information database and alignment identified similarity with group 8 allergens or glutathione S-transferases of Dermatophagoides pteronyssinus, Suidasia medanensis, Lepidoglyphus destructor, Glycyphagus domesticus, and Aleuroglyphus ovatus (64, 65, 53, 53, and 50 %, respectively). The first recombinant Der f 8 protein produced in full length successfully bound with patient IgE, demonstrating the importance of Der f 8 in mite allergy.

In silico structural analysis of group 3, 6 and 9 allergens from Dermatophagoides farinae

Dermatophagoides farinae (Hughes; Acari: Pyroglyphidae) are the predominant source of dust mite allergens, which provoke allergic diseases, such as rhinitis, asthma and eczema. Of the 30 allergen groups produced by D. farinae, the Der f 3, Der f 6 and Der f 9 allergens are all trypsin‑associated proteins, however little else is currently known about them. The present study used in silico tools to compare the amino acid sequences, and predict the secondary and tertiary structures of Der f 3, Der f 6 and Der f 9 allergens. Protein sequence alignment detected ~46% identity between Der f 3, Der f 6 and Der f 9. Furthermore, each protein was shown to contain three active sites and two highly conserved trypsin functional domains. Predictions of the secondary and tertiary structure identified α‑helices, β‑sheets and random coils. The active sites of the three proteins appeared to fold onto each other in a three‑dimensional model, constituting the active site of the enzyme. Epitope analysis demonstrated that Der f 3, Der f 6 and Der f 9 have 4‑5 potential epitopes located in random coils, and the epitope sequences of Der f 3, Der f 6 and Der f 9 were shown to overlap in two domains (at amino acids 83‑87 and 179‑180); however the residues in these two domains were not identical. The present study aimed to conduct a biochemical and genetic analysis of these three allergens, and to potentially contribute to the development of vaccines for allergen‑specific immunotherapy.

Cloning, expression, and analysis of a cDNA coding for the Dermatophagoides farinae group 21 (Der f 21) allergen

Domestic mite species like Dermatophagoides farinae induce allergies in people worldwide. Here, the cDNA coding for group 21 allergen of Dermatophagoides farinae (Hughes; Acari: Pyroglyphidae) from China was cloned, sequenced, and expressed in E. coli to aid in the development of diagnostic and treatment options for domestic mite hypersensitivity. First, the Der f 21 cDNA fragment was synthesized by RT-PCR; the confirmed full-length sequence comprised 411 nucleotides. The cDNA was ligated to the vector pCold-TF to construct an expression plasmid, pCold-TF-Der f 21. pCold-Tf-Der f 21 was transformed into E. coli BL21 cells, and its expression was induced by IPTG treatment. SDS-PAGE showed a specific band at the predicted molecular weight of Der f 21, demonstrating its successful expression. The recombinant fusion protein was obtained and its structure and molecular weight were confirmed by MALDI-TOF/TOF. Bioinformatics analysis revealed that the protein contained a signal peptide of 17 amino acids. The molecular weight of the mature Der f 21 allergen was approximately 14.16 kDa with a theoretical pI of 4.87. Its predicted secondary structure comprises a-helix (84.03%), extension chain (1.68%), and random coil (14.29%). The successful cloning of Der f 21 and a basic bioinformatics analysis of the protein provide a foundation for further study of this allergen in diagnosis and treatment of domestic mite hypersensitivity.

When mites attack: domestic mites are not just allergens

Domestic mite species found in indoor environments and in warm or tropical regions are well known for causing allergic disorders. However, little is known about human acariasis, in which mites invade and parasitize the human body in various tissues from the gastrointestinal tract to the lung. Here, we summarize the reported cases of human acariasis of pulmonary, intestinal, oral (anaphylaxis), urinary, otic, and vaginal systems. Because the clinical symptoms of acariasis often overlap with other disease symptoms leading to frequent misdiagnosis, we highlight the need for more attention on these infections.