Immunoglobulin E-binding epitopes of mite allergens: from characterization to immunotherapy

Targeted suppression of Dpt-specific B cells in humanized Rag2- γc- mouse model of HDM allergy

Der p 1 is one of the major allergenic molecules of Dermatophagoides pteronyssinus, causing house dust mite (HDM) allergy. The pathological B cells produce allergen-specific IgE antibodies that mediate the hypersensitivity reaction, therefore the selective elimination of these B cells is a legitimate therapeutic goal in allergy. Chimeric molecule Dp51-72 able to cross-link B cell inhibitory complement receptor type 1 and BCR on Der p 1-specific B cells was constructed. The signalling capabilities of this molecule have been tested on human B cells. A humanized mouse model of HDM allergy has been used to test the in vivo effects of the chimeric molecule administration. Administering the chimeric molecule to immunodeficient Rag2- γc- mice transferred with PBMCs from allergic patients resulted in reduction of allergen-specific IgE antibodies in the sera, and reduced infiltration of immune cells in lung histology preparations. Reduced numbers of human CD45⁺ and CD4⁺ cells in the lungs as well as inhibition of mast cell degranulation were also observed. The treatment with Dp51-72 chimera significantly decreased the local levels of anti-Dpt IgE antibodies in the bronchoalveolar lavage fluid (BALF). The binding of the chimeric molecule to tonsillar B cells triggers the tyrosine phosphorylation of 30-32 kDa protein, which is most likely involved in the inhibitory process. Administration of constructed chimeric molecules to humanized mice with developed inflammation resulted in specific suppression of disease-associated IgE antibody-producing cells and preserved lung histology. This effective approach could be further developed into a therapeutic agent for treatment of patients with HDM allergy.

Expression, epitope prediction and IgE-binding of the Tyrophagus putrescentiae group 13 allergen

Storage mites, such as Tyrophagus putrescentiae, are an important source of allergens that cause allergic diseases in humans. It has previously been indicated that T. putrescentiae has a high sensitization rate as an allergen in some Asian and European countries. Identifying and cloning the allergens in this species may enable improved diagnostic and therapeutic approaches. The aim of the present study was to clone and sequence the T. putrescentiae group 13 allergen (Tyr p 13) isolated from storage mites in China, to use bioinformatics tools to model its biophysical characteristics and to induce protein expression to test its IgE-binding activity. The full-length cDNA comprised 486 bp and was predicted to include a signal peptide of 22 amino acids. Its secondary structure was shown to comprise an α-helix (10.79%), extended strand (33.81%) and random coils (55.40%). Using homology modeling, the present study constructed a reasonable tertiary structure of Tyr p 13. Linear Bcell epitopes at amino acids 47-53, 70-76, 81-86, 101-105 and 112120 were predicted. Three discontinuous B-cell epitopes were also predicted: i) 47, 48, 49, 50, 51, 52, 53, 70, 71, 72 and 73; ii) 91, 92, 93, 94, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121 and 138; and iii) 74, 76, 79, 81, 82, 83, 84, 86, 101, 102, 103, 104 and 105. SDS-PAGE identified a specific band at the predicted molecular weight of the recombinant Tyr p 13 (rTyr p 13), demonstrating its successful expression. The rTyr p 13 bound to IgE in the serum of 13.2% (5/38) of patients allergic to T. putrescentiae, according to ELISA. The successful cloning of Tyr p 13 and basic bioinformatics analysis of the protein provided a foundation for the further study of this allergen with regards to the diagnosis and treatment of patients allergic to storage mites. These results provided a theoretical basis for the design of rTyr p 13 with modified B-cell epitopes.

Identification the Cross-Reactive or Species-Specific Allergens of Tyrophagus putrescentiae and Development Molecular Diagnostic Kits for Allergic Diseases

Mite allergens are considerable factors in the genesis of allergic diseases. The storage mite Tyrophagus putrescentiae (Tp) appears in contaminated foods and household surroundings. The current diagnostic tools for Tp allergy are mostly based on crude extracts and still contain shortcomings. This study aimed to investigate the immunoglobulin E (IgE)- responsiveness profiles of Tp-allergic patients and develop a molecular diagnostic method using recombinant allergens. Allergenic components were characterized as cross-reacting or species-specific allergens, in which the effective combinations of recombinant allergens were developed and analyzed in terms of the prediction accuracy for clinical diagnosis. Seven recombinant allergens were cloned and generated to detect the IgE responsiveness of the Tp allergy. A survey on the prevalence of mite allergy showed there were higher sensitizations with IgE responsiveness to house dust mites (HDM) (78.9-80.9%) than to storage mites Tp (35.6%). Prevalence of sensitization to Tp was higher in elderly subjects. The principal IgE-binding components of Tp were Tyr p 1, Tyr p 2 and Tyr p 3. Prediction accuracy for Tp allergy by IgE-responsiveness combination D (Tyr p 1, Tyr p 2 & Tyr p 3) was with high precision (100%). Avoiding the cross-reactivity of Dermatophagoides pteronyssinus, the prediction accuracy of IgE-responsiveness combination H+ (Tyr p 1, Tyr p 2, Tyr p 3, Tyr p 7, Tyr p 8, Tyr p 10 & Tyr p 20) was suitable for Tp-specific diagnosis. Panels of Tp allergens were generated and developed a diagnostic kit able beneficial to identify IgE-mediated Tp hypersensitivity.

Identification of continuous immunoglobulin G epitopes of Dermatophagoides farinae allergens by peptide microarray immunoassay

Dermatophagoides farinae, as a common house dust mite species, is one of the main sources of allergens in the world. At present, Dermatophagoides farinae is found to contain more than 30 groups of allergens. These allergens are used for allergen-specific immunotherapy (AIT) of allergic diseases. During the AIT process, immunoglobulin G (IgG) antibodies can block immunoglobulin E (IgE) antibody-induced allergic reactions in the human body. One of the mechanisms may be that IgG and IgE competitively bind to the same allergic protein, so it is necessary to explore the binding sites (epitopes) of IgG antibodies to allergens. In this study, peptide arrays were constructed to react with the serums from patients with allergic asthma to find the IgG epitopes of several allergens including major allergens (Der f 1, 2) and mid-tier allergens (Der f 4, 5, and 7), and then verified by enzyme-linked immunosorbent assay (ELISA) test. Relevant epitopic sequences were located on the tertiary structure of individual allergens, as reconstructed by homology modeling. One IgG epitope of Der f 1 (90-106aa, NVPSELDLRSLRTVTPI), five IgG epitopes of Der f 4 (61-77aa, ERYQPVSYDIHTRSGDE; 193-209aa, FRSDASTHQWPDDLRSI; 226-242aa, HPFIYHETIYYGGNGIN; 271-287aa, LRWLRNFGTEWGLVPSG; 352-368aa, NDWVGPPTDQHGNILSV), and one IgG epitope of Der f 5 (84-101aa, RYNVEIALKSNEILERDL) were identified. IgG epitopes of Der f 2, 7 were not found. There are overlaps between the IgG and IgE epitopes of Der f 1, 4, and 5. These findings not only reflect the practicality of peptide array and ELISA test in the allergen IgG epitope identification, but also provide more information for further understanding of the human immunological changes during AIT and the molecular mechanisms of IgG blocking IgE activity.

Preventive sublingual immunotherapy with House Dust Mite extract modulates epitope diversity in pre-school children

BACKGROUND

The preventive effect of allergen immunotherapy (AIT) on allergy and asthma development is currently assessed using primary and secondary AIT approaches. Knowledge of the immunological effects of these interventions is limited and the impact on epitope diversity remains to be defined.

METHODS

We used high-density peptide arrays that included all known Dermatophagoides pteronyssinus (Der p) and Dermatophagoides farinae (Der f) allergens and the whole proteome of Der f to study changes in House Dust Mite (HDM) linear peptide recognition during a 2-year preventive double-blind placebo-controlled sublingual HDM AIT pilot study in 2-5-year-old children with sensitization to HDM but without symptoms.

RESULTS

Preventive AIT-treated patients showed significantly higher IgG epitope diversity to HDM allergens compared to placebo-treated individuals at 24 months of treatment (P < 0.05), while no increase in IgE diversity was seen. At 24 months of treatment, IgG4 diversity for HDM allergens was significantly higher in the pAIT-treated patients compared to placebo group (P < 0.05). Potentially beneficial changes in epitope recognition throughout the treatment are also seen in peptides derived from Der f proteome.

CONCLUSION

These data suggest a beneficial immunomodulation of preventive sublingual immunotherapy at a molecular level by favoring a broader blocking repertoire and inhibiting epitope spreading.

Domestic mite-induced allergy: Causes, diagnosis, and future prospects

Allergies to various environmental factors, in particular mite species, represent a considerable healthcare burden with lost productivity resulting from symptoms including asthma, conjunctivitis, rhinitis, and atopic dermatitis. The complexity of mite species and the allergens that they produce complicates diagnosis and treatment; however, the advent of recombinant DNA technologies now allows clinicians to better pinpoint the specific sensitizing agents and creates new opportunities for avoidance or immunotherapy. Here we discuss the advantages and disadvantages of traditional and novel diagnostic and therapeutic platforms, with particular consideration given to multiplex tests able to generate patient-specific allergen profiles. Immunotherapies tailored to such profiles may be safer and more effective than generalized treatments, but many hurdles, including the costs associated with identifying the protein or protein combinations able to exert the safest and most beneficial effects, must be overcome before such therapies can be globally applied.

Homology modeling and prediction of B‑cell and T‑cell epitopes of the house dust mite allergen Der f 20

House dust mite allergens can cause allergic diseases, including asthma, atopic dermatitis and rhinitis. Der f 20 is a novel allergen of Dermatophagoides farina (Der f), which is an arginine kinase. In the present study, the B‑cell and T‑cell epitopes of Der f 20 were predicted. The protein attribution, patterns, physicochemical properties and secondary structure of Der f 20 were also predicted. Der f 20 is a member of the ATP:guanido phosphotransferase family and contains a phosphagen kinase pattern. Using homology modeling, the present study constructed a reasonable tertiary structure of Der f 20. Using BcePred, ABCpred, BCPred and BPAP systems, B‑cell epitopes at 20‑25, 41‑49, 111‑118, 131‑141, 170‑174 and 312‑321 were predicted. Using NetMHCIIpan‑3.0 and NetMHCII‑2.2, T‑cell epitopes were predicted at 194‑202, 239‑247 and 274‑282. These results provide a theoretical basis for the design off Der f 20 epitope‑based vaccines.

Antibodies and superantibodies in patients with chronic rhinosinusitis with nasal polyps

Background

Chronic rhinosinusitis with nasal polyps is associated with local immunoglobulin hyperproduction and the presence of IgE antibodies against Staphylococcus aureus enterotoxins (SAEs). Aspirin-exacerbated respiratory disease is a severe form of chronic rhinosinusitis with nasal polyps in which nearly all patients express anti-SAEs.

Objectives

We aimed to understand antibodies reactive to SAEs and determine whether they recognize SAEs through their complementarity-determining regions (CDRs) or framework regions.

Methods

Labeled staphylococcal enterotoxin (SE) A, SED, and SEE were used to isolate single SAE-specific B cells from the nasal polyps of 3 patients with aspirin-exacerbated respiratory disease by using fluorescence-activated cell sorting. Recombinant antibodies with “matched” heavy and light chains were cloned as IgG₁, and those of high affinity for specific SAEs, assayed by means of ELISA and surface plasmon resonance, were recloned as IgE and antigen-binding fragments. IgE activities were tested in basophil degranulation assays.

Results

Thirty-seven SAE-specific, IgG- or IgA-expressing B cells were isolated and yielded 6 anti-SAE clones, 2 each for SEA, SED, and SEE. Competition binding assays revealed that the anti-SEE antibodies recognize nonoverlapping epitopes in SEE. Unexpectedly, each anti-SEE mediated SEE-induced basophil degranulation, and IgG₁ or antigen-binding fragments of each anti-SEE enhanced degranulation by the other anti-SEE.

Conclusions

SEEs can activate basophils by simultaneously binding as antigens in the conventional manner to CDRs and as superantigens to framework regions of anti-SEE IgE in anti-SEE IgE-FcεRI complexes. Anti-SEE IgG₁s can enhance the activity of anti-SEE IgEs as conventional antibodies through CDRs or simultaneously as conventional antibodies and as “superantibodies” through CDRs and framework regions to SEEs in SEE–anti-SEE IgE-FcεRI complexes.

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.

The challenge of treating orphan disease

Uncommon or orphan diseases are less frequently addressed in mainstream medical journals and, as a consequence, their understanding and clinical recognition may rely on case series or anecdotal data with limited guidelines and management directions. The study of selected underrepresented autoimmune and allergy conditions is the subject of the present issue of Clinical Reviews in Allergy and Immunology to provide peculiar perspectives on common and rare themes. First, allergy remains a major concern for physicians worldwide despite the limited developments over the past years, particularly for antigens such as mite or Alternaria alternata, and due to the increasing incidence of drug hypersensitivity. Second, the female predominance of autoimmune diseases such as systemic sclerosis is well recognized but enigmatic, and a unifying hypothesis remains elusive. Third, the management of conditions triggered by infectious agents as in Guillain-Barre syndrome or mixed cryoglobulinemia is challenging, and clinical guidelines are needed in the setting of infections and autoimmunity. Fourth, gamma-delta T cells represent major players in innate immunity and are the subject of extensive studies in autoimmune diseases to provide new therapeutic targets for disease prevention or modulation in the near future. Ultimately, we acknowledge the major developments in the broad fields of rheumatology and immunology and expect that microbiota definition, epigenetics studies, and microRNA analysis will provide new exciting avenues toward the understanding and treatment of chronic and acute inflammation.

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.

In Silico Prediction of T and B Cell Epitopes of Der f 25 in Dermatophagoides farinae

The house dust mites are major sources of indoor allergens for humans, which induce asthma, rhinitis, dermatitis, and other allergic diseases. Der f 25 is a triosephosphate isomerase, representing the major allergen identified in Dermatophagoides farinae. The objective of this study was to predict the B and T cell epitopes of Der f 25. In the present study, we analyzed the physiochemical properties, function motifs and domains, and structural-based detailed features of Der f 25 and predicted the B cell linear epitopes of Der f 25 by DNAStar protean system, BPAP, and BepiPred 1.0 server and the T cell epitopes by NetMHCIIpan-3.0 and NetMHCII-2.2. As a result, the sequence and structure analysis identified that Der f 25 belongs to the triosephosphate isomerase family and exhibited a triosephosphate isomerase pattern (PS001371). Eight B cell epitopes (11-18, 30-35, 71-77, 99-107, 132-138, 173-187, 193-197, and 211-224) and five T cell epitopes including 26-34, 38-54, 66-74, 142-151, and 239-247 were predicted in this study. These results can be used to benefit allergen immunotherapies and reduce the frequency of mite allergic reactions.