RESUMO
BACKGROUND: The SQ tree SLIT-tablet (containing birch extract) proved clinically significant effects during the pollen season for birch as well as alder/hazel. Immune outcomes of this treatment for allergens from multiple birch homologous trees need further investigation. We hypothesize that birch pollen extract AIT modulates a highly cross-reactive immune response and that this may be the basis for the observed clinical cross-protection. METHODS: Blood samples were collected from 397 birch allergic patients during SQ tree SLIT-tablet or placebo treatment (1:1) for up to 40 weeks. Serum IgE and IgG4 specific to birch, and birch homologous tree pollens from alder, hazel, hornbeam, beech and chestnut were measured by ImmunoCAP. IgE-Blocking Factor (IgE-BF) for alder, birch and hazel during treatment was measured by Advia Centaur and blocking effects for birch and all these birch homologous tree pollens were further investigated by basophil activation (BAT). Antibody readouts were investigated in patient subsets. T-cell responses (proliferation) to allergen extracts and peptide pools (group 1 allergens) were investigated in T-cell lines from 29 untreated birch pollen-allergic individuals. RESULTS: Significant Pearson correlations between serum IgE towards birch, alder, hazel, hornbeam and beech were observed (r-values > .86). T-cell reactivity was observed throughout the birch homologous group. Almost identical kinetics for changes in IgE towards birch, alder and hazel were observed during treatment and similar species-specific changes were seen for serum-IgG4 . IgG4 reactivity towards birch and alder, hazel, hornbeam and beech correlated significantly at end-of-treatment (r-values > .72). Treatment resulted in similar IgE-BF kinetics for alder, birch, and hazel and blocking of BAT for multiple trees in most actively treated patients investigated. CONCLUSIONS: Systematic analyses of T-cell and antibody cross-reactivities before and during birch pollen extract AIT provide the immunological basis for the observed clinical effect of SQ tree SLIT-tablet treatment of tree pollen allergy induced by multiple trees in the birch homologous group.
Assuntos
Betula/imunologia , Imunoglobulina E/imunologia , Imunoglobulina G/imunologia , Rinite Alérgica Sazonal/terapia , Imunoterapia Sublingual/métodos , Aesculus/imunologia , Alnus/imunologia , Teste de Degranulação de Basófilos , Betulaceae/imunologia , Corylus/imunologia , Reações Cruzadas/imunologia , Fagus/imunologia , Humanos , Rinite Alérgica Sazonal/imunologia , Linfócitos T/imunologiaRESUMO
BACKGROUND: Increased epithelial permeability has been reported in allergic rhinitis, with histamine and type-2 inflammation being responsible for tight junction dysfunction. The impact of an epithelial barrier defect on allergic sensitization and mast cell (MC) degranulation remains speculative. METHODS: Transepithelial passage of allergens was evaluated on primary human nasal epithelial cell cultures. Active sensitization was attempted by repeated intranasal ovalbumin (OVA) applications in Naïve mice. In a passive sensitization model, mice were injected with IgE to Dermatophagoides pteronyssinus (rDer p)2 and then exposed intranasally to the allergen. Chitosan was used to disrupt nasal epithelial integrity in vitro and in vivo. RESULTS: Chitosan strongly reduced transepithelial electrical resistance and facilitated transepithelial allergen passage in cultured primary nasal epithelial cells. In vivo, intranasal chitosan affected occludin expression and facilitated allergen passage. After epithelial barrier disruption, intranasal OVA application induced higher OVA-specific IgG1 and total IgE in serum, and increased eosinophilia and interleukin-5 in bronchoalveolar lavage (BAL) compared to sham-OVA mice. Chitosan exposure, prior to rDer p2 allergen challenge in passively sensitized mice, resulted in increased ß-hexosaminidase levels in serum and BAL compared to sham-rDer p2 mice. Intranasal treatment with the synthetic glucocorticoid fluticasone propionate prevented chitosan-induced barrier dysfunction, allergic sensitization, and MC degranulation. CONCLUSION: Epithelial barrier dysfunction facilitates transepithelial allergen passage, allergic sensitization, and allergen-induced MC degranulation even in the absence of inflammatory environment. These results emphasize the crucial role of an intact epithelial barrier in prevention of allergy.
Assuntos
Mastócitos , Rinite Alérgica , Alérgenos , Animais , Degranulação Celular , Inflamação , Camundongos , Camundongos Endogâmicos BALB C , OvalbuminaRESUMO
BACKGROUND: House dust mite (HDM) allergens are a common cause of allergy and allergic asthma. A comprehensive analysis of proteins targeted by T cells, which are implicated in the development and regulation of allergic disease independent of their antibody reactivity, is still lacking. OBJECTIVE: To comprehensively analyse the HDM-derived protein targets of T cell responses in HDM-allergic individuals, and investigate their correlation with IgE/IgG responses and protein function. METHODS: Proteomic analysis (liquid chromatography-tandem mass spectrometry) of HDM extracts identified 90 distinct protein clusters, corresponding to 29 known allergens and 61 novel proteins. Peripheral blood mononuclear cells (PBMC) from 20 HDM-allergic individuals were stimulated with HDM extracts and assayed with a set of ~2500 peptides derived from these 90 protein clusters and predicted to bind the most common HLA class II types. 2D immunoblots were made in parallel to elucidate IgE and IgG reactivity, and putative function analyses were performed in silico according to Gene Ontology annotations. RESULTS: Analysis of T cell reactivity revealed a large number of T cell epitopes. Overall response magnitude and frequency was comparable for known and novel proteins, with 15 antigens (nine of which were novel) dominating the total T cell response. Most of the known allergens that were dominant at the T cell level were also IgE reactive, as expected, while few novel dominant T cell antigens were IgE reactive. Among known allergens, hydrolase activity and detectable IgE/IgG reactivity are strongly correlated, while no protein function correlates with immunogenicity of novel proteins. A total of 106 epitopes accounted for half of the total T cell response, underlining the heterogeneity of T cell responses to HDM allergens. CONCLUSIONS AND CLINICAL RELEVANCE: Herein, we define the T cell targets for both known allergens and novel proteins, which may inform future diagnostics and immunotherapeutics for allergy to HDM.
Assuntos
Alérgenos/imunologia , Antígenos de Dermatophagoides/imunologia , Hipersensibilidade/imunologia , Hipersensibilidade/metabolismo , Proteoma , Proteômica , Linfócitos T/imunologia , Sequência de Aminoácidos , Especificidade de Anticorpos/imunologia , Biologia Computacional , Epitopos de Linfócito T/química , Epitopos de Linfócito T/imunologia , Antígenos de Histocompatibilidade Classe II/imunologia , Humanos , Hipersensibilidade/sangue , Epitopos Imunodominantes/química , Epitopos Imunodominantes/imunologia , Imunoglobulina E/sangue , Imunoglobulina E/imunologia , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , Proteômica/métodos , Linfócitos T/metabolismoRESUMO
Allergen-specific immunoglobulin E (IgE) antibodies mediate pathology in diseases such as allergic rhinitis and food allergy. Memory B cells (MBCs) contribute to circulating IgE by regenerating IgE-producing plasma cells upon allergen encounter. Here, we report a population of type 2-polarized MBCs defined as CD23hi, IL-4Rαhi, and CD32low at both the transcriptional and surface protein levels. These MBC2s are enriched in IgG1- and IgG4-expressing cells while constitutively expressing germline transcripts for IgE. Allergen-specific B cells from patients with allergic rhinitis and food allergy were enriched in MBC2s. Furthermore, MBC2s generated allergen-specific IgE during sublingual immunotherapy, thereby identifying these cells as a major reservoir for IgE. The identification of MBC2s provides insights into the maintenance of IgE memory, which is detrimental in allergic diseases but could be beneficial in protection against venoms and helminths.
Assuntos
Hipersensibilidade Alimentar , Rinite Alérgica Sazonal , Rinite Alérgica , Humanos , Rinite Alérgica Sazonal/metabolismo , Células B de Memória , Alérgenos , Imunoglobulina E , Imunoglobulina GRESUMO
OBJECTIVE: The contribution of affinity, clonality, and concentration of individual IgE species to effector cell response has recently been characterized in a model with recombinant human IgE on passively sensitized basophils. This study extends the dependence of effector cell degranulation on IgE concentration to mast cells cultured with IgE for 2 weeks. METHODS: Human mast cells cultured for 7 weeks from peripheral blood stem cells were matured for 2 weeks with interleukin-4 (IL-4) and recombinant human IgE consisting of two clones specific for Dermatophagoides pteronyssinus 2 (Derp2) (7% + 7%) and unspecific IgE at 0.8, 8, 80, and 800 kU/L. The density of the IgE receptor, FcϵRI, and mast cell function were measured after challenging with recombinant Derp2 at 14 concentrations from 10 fg/mL to 100 pg/mL. CD63 expression, histamine release, and Prostaglandin D2 (PGD(2)) synthesis were measured, and maximal expression and mast cell sensitivity were calculated. RESULTS: At 800 kU/L IgE, FcϵRI expression varied more than at 80, 8, and 0.8 kU/L IgE. There was a trend toward increased maximal expression of CD63, histamine release, and PGD(2) secretion with increasing IgE concentration. At 0.1 kU/L specific IgE, the LC50 increased up to fivefold, least so for PGD(2). CONCLUSIONS: Human mast cells cultured with rhIgE of known composition are a sensitive model for studying factors governing effector cell degranulation that is close to the in vivo situation. This model can be used to study effects of IgE concentration, clonality, and affinity and may help predict the optimal immunologic treatment for a given patient.
Assuntos
Antígenos de Dermatophagoides/imunologia , Degranulação Celular/imunologia , Hipersensibilidade/imunologia , Imunoglobulina E/imunologia , Mastócitos/imunologia , Receptores de IgG/imunologia , Liberação de Histamina/imunologia , Humanos , Leucócitos Mononucleares/imunologia , Prostaglandina D2/imunologia , Estatísticas não Paramétricas , Tetraspanina 30/imunologiaRESUMO
Background: Allergens from Fagales trees frequently cause spring allergy in Europe, North America, and some parts of Asia. The definition of the birch homologous group, which includes birch (Bet v), oak (Que a), alder (Aln g), hazel (Cor a), hornbeam (Car b), beech (Fag s), and chestnut (Cas s), is based on high allergen sequence identity and extensive IgE cross-reactivity. Clinical effect was seen during the alder/hazel, birch, and oak pollen seasons after treatment with tree SLIT-tablets containing only birch allergen extract. Here, we characterize T-cell reactivity with respect to epitope specificities and cross-reactivity toward various Bet v 1 family members, (PR-10/group 1 major allergens). This cross-reactivity may be part of the immunological basis of clinical effect or cross-protection when exposed to birch homologous tree species. Method: T-cell lines were generated from 29 birch-allergic individuals through stimulation of peripheral blood mononuclear cells (PBMCs) with birch/Bet v or oak/Que a allergen extracts. T-cell responses to allergen extracts, purified group 1 allergens, and overlapping 20-mer peptides (Bet v 1, Aln g 1, Cor a 1, and Que a 1) were investigated by T-cell proliferation and cytokine production. Cross-reactivity was evaluated based on Pearson's correlations of response strength and further investigated by flow cytometry using tetramer staining for homologous peptide pairs. Results: T-cell reactivity toward extracts and group 1 allergens from across the birch homologous group was observed for birch/Bet v as well as oak/Que a T-cell lines. T-cell lines responded to multiple Bet v 1 homologous peptides from Aln g 1 and Cor a 1 and a subset of Que a 1 peptides. Significant Pearson's correlations between frequently recognized peptides derived from Bet v 1 and the corresponding peptides derived from alder, hazel, and oak strongly supported the T-cell cross-reactivity toward these allergens. Cross-reactivity between birch and birch homologous peptides was confirmed by pMHCII tetramer staining. Conclusion: T cells from birch tree pollen allergic individuals respond to multiple trees within the birch homologous group in accordance with the level of sequence homology between Bet v 1 family members, (PR-10 allergens) from these allergen sources, confirming the basis for clinical cross-protection.
Assuntos
Hipersensibilidade , Árvores , Humanos , Linfócitos T , Leucócitos Mononucleares , Antígenos de Plantas , Pólen , Alérgenos , Peptídeos/análise , BetulaRESUMO
BACKGROUND: Allergen-specific immunotherapy (SIT) leads to reduced symptoms upon allergen exposure through as yet unresolved mechanisms. Desensitization of basophils to specific allergens during the updosing phase of injection immunotherapy may contribute to the clinical effect of SIT. Here we report a protocol for efficient in vitro allergen-mediated desensitization of basophils in whole blood and the effect of desensitization on the expression of basophil activation markers (CD203c and CD63) as well as histamine release in response to allergen challenge. METHODS: Whole blood from grass pollen-allergic subjects was incubated with Phleum pratense extract by stepwise increase of the allergen concentration in the culture from well below to well above the allergen threshold concentration for activation of basophils. Desensitization was determined by measuring the expression of the basophil activation markers CD63 and CD203c by FACS following challenge with high allergen concentrations. RESULTS: The basophil desensitization protocol reported here affected both the expression of the cell-surface markers and the levels of histamine release. Following the stepwise desensitization procedure the whole-blood basophils were not activated when challenged with more than 10-fold increased allergen concentration. CONCLUSION: We have established a protocol for basophil desensitization. By mimicking the updosing phase of immunotherapy we raised the allergen threshold for basophil activation and obtained efficient desensitization for all donors. We showed that conditions leading to desensitization affect histamine release and expression of different basophil markers alike.
Assuntos
Antígenos CD/metabolismo , Basófilos/metabolismo , Dessensibilização Imunológica , Diester Fosfórico Hidrolases/metabolismo , Glicoproteínas da Membrana de Plaquetas/metabolismo , Pirofosfatases/metabolismo , Rinite Alérgica Sazonal/imunologia , Alérgenos/imunologia , Alérgenos/metabolismo , Antígenos CD/imunologia , Teste de Degranulação de Basófilos , Basófilos/imunologia , Basófilos/patologia , Biomarcadores/metabolismo , Separação Celular , Células Cultivadas , Relação Dose-Resposta Imunológica , Citometria de Fluxo , Histamina/metabolismo , Humanos , Phleum , Diester Fosfórico Hidrolases/imunologia , Proteínas de Plantas/imunologia , Proteínas de Plantas/metabolismo , Glicoproteínas da Membrana de Plaquetas/imunologia , Pirofosfatases/imunologia , Rinite Alérgica Sazonal/diagnóstico , Rinite Alérgica Sazonal/tratamento farmacológico , Tetraspanina 30RESUMO
BACKGROUND: On cross-linking of receptor-bound IgE antibodies by allergens, effector cells (basophils and mast cells) involved in type I allergic reactions degranulate and release the potent chemical mediators stored inside their granules. Total and allergen-specific IgE concentrations, IgE affinity for allergen, and IgE clonality are all distinct properties of allergic patients' IgE repertoires. However, the inability to isolate individual IgE antibodies from allergic patients' sera presents a major barrier to understanding the importance of patient-specific IgE repertoires for the manifestation and severity of allergic symptoms. OBJECTIVE: We sought to investigate how individual properties of an IgE repertoire affect effector cell degranulation. METHODS: A panel of recombinant IgE (rIgE) antibodies specific for the major house dust mite allergen Der p 2 was developed and characterized in regard to Der p 2 affinity, as well as Der p 2 epitope specificity, by using surface plasmon resonance technology. Human basophils were sensitized with different combinations of rIgEs, and degranulation responses were measured by means of flow cytometry after challenge with Der p 2. RESULTS: A total of 31 Der p 2-specific rIgEs were produced. They bound a total of 9 different Der p 2 epitopes in the affinity range (K(D) value) of 0.0358 to 291 nM. Factors increasing human basophil degranulation were increased total IgE concentrations, increased concentrations of allergen-specific IgE relative to non-allergen-specific IgE, more even concentration of individual allergen-specific IgE clones, increased IgE affinity for allergen, and increased number of allergen epitopes recognized by the IgE repertoire (increased IgE clonality). CONCLUSION: This study demonstrates how distinct properties of the IgE repertoire, such as total and allergen-specific IgE antibody concentration, IgE affinity, and IgE clonality, affect effector cell degranulation.
Assuntos
Antígenos de Dermatophagoides/imunologia , Basófilos/imunologia , Degranulação Celular/imunologia , Hipersensibilidade Imediata/imunologia , Imunoglobulina E/imunologia , Mastócitos/imunologia , Animais , Afinidade de Anticorpos , Especificidade de Anticorpos , Antígenos de Dermatophagoides/metabolismo , Proteínas de Artrópodes , Basófilos/metabolismo , Linhagem Celular , Mapeamento de Epitopos , Epitopos/imunologia , Humanos , Imunoglobulina E/metabolismo , Mastócitos/metabolismo , Proteínas Recombinantes de Fusão/imunologia , Proteínas Recombinantes de Fusão/metabolismoRESUMO
BACKGROUND: In Europe, specific immunotherapy is currently conducted with vaccines containing allergen preparations based on intact extracts. In addition to this, chemically modified allergen extracts (allergoids) are used for specific allergy treatment. Reduced allergenicity and thereby reduced risk of side effects in combination with retained ability to activate T cells and induce protective allergen-specific antibody responses has been claimed for allergoids. In the current study, we compared intact allergen extracts and allergoids with respect to allergenicity and immunogenicity. METHODS: The immunological response to birch allergen extract, alum-adsorbed extract, birch allergoid and alum-adsorbed allergoid was investigated in vitro in human basophil histamine release assay and by stimulation of human allergen-specific T cell lines. In vivo, Bet v 1-specific IgG titers in mice were determined after repetitive immunizations. RESULTS: In all patients tested (n = 8), allergoid stimulations led to reduced histamine release compared to the intact allergen extract. However, the allergoid preparations were not recognized by Bet v 1-specific T cell lines (n = 7), which responded strongly to the intact allergen extract. Mouse immunizations showed a clearly reduced IgG induction by allergoids and a strongly potentiating effect of the alum adjuvant. Optimal IgG titers were obtained after 3 immunizations with intact allergen extracts, while 5 immunizations were needed to obtain maximal response to the allergoid. CONCLUSION: The reduced histamine release observed for allergoid preparations may be at the expense of immunological efficacy because the chemical modifications lead to a clear reduction in T cell activation and the ability to induce allergen-specific IgG antibody responses.
Assuntos
Alérgenos/farmacologia , Antígenos de Plantas/farmacologia , Betula/imunologia , Extratos Vegetais/farmacologia , Proteínas de Plantas/farmacologia , Adsorção , Alérgenos/química , Alérgenos/imunologia , Alergoides , Compostos de Alúmen/química , Animais , Antígenos de Plantas/química , Antígenos de Plantas/imunologia , Linhagem Celular , Glutaral/química , Histamina/metabolismo , Humanos , Hipersensibilidade , Imunização , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Extratos Vegetais/química , Extratos Vegetais/imunologia , Proteínas de Plantas/química , Proteínas de Plantas/imunologia , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologiaRESUMO
Effector cell activation and T-cell activation, the latter mediated by facilitated antigen presentation, are immunological mechanisms that play crucial roles in the manifestation and maintenance of allergic disease. In addition to their relevance for the pathogenesis of allergy in-vivo, in-vitro assays based on these immunological mechanisms have been established and used for diagnostics, for monitoring the progression of disease and for the effect of specific immunotherapy as well as for basic research purposes. Here we review different parameters that affect effector cell activation and facilitated antigen uptake and presentation, including assay designs, readout parameters and critical experimental conditions. Central to the two immunological mechanisms is complex formation between allergen-specific IgE, allergen, and cell surface-anchored immunoglobulin receptor; the high affinity IgE-receptor FcεRI on basophils and mast cells, and the low affinity IgE-receptor FcεRII (CD23) on B-cells. Accordingly, the effect of IgE repertoire complexity and allergen diversity on effector cell and facilitated antigen presentation is discussed in detail.