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Keywords: Allergic inflammation; Alveolar macrophages; Aspergillus fumigatus; CARD9 EN Allergic inflammation Alveolar macrophages Aspergillus fumigatus CARD9 659 663 5 06/09/23 20230601 NES 230601 Key message CARD9 enhances pro-inflammatory immune response, but inhibits pulmonary type 2 immunity after I A. fumigatus i exposure. Moreover, we sorted out alveolar macrophages from WT and CARD9 deficient mice infected with/without I A. fumigatus i , and further confirmed that RelB activation only occurred in CARD9 deficient alveolar macrophages. Simultaneously, we found that the expression of CD80, CD86 and MHC-II were comparable between WT and CARD9 deficient mice with/without I A. fumigatus i exposure, hinting that CARD9 did not affect the antigen presentation capacity of alveolar macrophages. CARD9 balances Aspergillus fumigatus-induced anti-fungal immunity and allergic inflammation. [Extracted from the article]

Innate immune cells experience long lasting metabolic and epigenetic changes after an encounter with specific stimuli. This facilitates enhanced immune responses upon secondary exposition to both the same and unrelated pathogens, a process termed trained immunity. Trained immunity‐based vaccines (TIbV) are vaccines able to induce innate immune memory, thus conferring heterologous protection against a broad range of pathogens. While trained immunity has been well documented in the context of infections and multiple immune‐mediated diseases, the role of innate immune memory and its contribution to the initiation and maintenance of chronic allergic diseases remains poorly understood. Over the last years, different studies attempting to uncover the role of trained immunity in allergy have emerged. Exposition to environmental factors impacting allergy development such as allergens or viruses induces the reprogramming of innate immune cells to acquire a more pro‐inflammatory phenotype in the context of asthma or food allergy. Several studies have convincingly demonstrated that prevention of viral infections using TIbV contributes to reduce wheezing attacks in children, which represent a high‐risk factor for asthma development later in life. Innate immune cells trained with specific stimuli might also acquire anti‐inflammatory features and promote tolerance, which may have important implications for chronic inflammatory diseases such as allergies. Recent findings showed that allergoid‐mannan conjugates, which are next generation vaccines for allergen‐specific immunotherapy (AIT), are able to reprogram monocytes into tolerogenic dendritic cells by mechanisms depending on metabolic and epigenetic rewiring. A better understanding of the underlying mechanisms of trained immunity in allergy will pave the way for the design of novel trained immunity‐based allergen vaccines as potential alternative strategies for the prevention and treatment of allergic diseases. [ABSTRACT FROM AUTHOR]

Background The gut microbiota is established during infancy and plays a fundamental role in shaping host immunity. Colonization patterns may influence the development of atopic disease, but existing evidence is limited and conflicting. Objective To explore associations of infant gut microbiota and food sensitization. Methods Food sensitization at 1 year was determined by skin prick testing in 166 infants from the population-based Canadian Healthy Infant Longitudinal Development ( CHILD) study. Faecal samples were collected at 3 and 12 months, and microbiota was characterized by Illumina 16S rRNA sequencing. Results Twelve infants (7.2%) were sensitized to ≥ 1 common food allergen at 1 year. Enterobacteriaceae were overrepresented and Bacteroidaceae were underrepresented in the gut microbiota of food-sensitized infants at 3 months and 1 year, whereas lower microbiota richness was evident only at 3 months. Each quartile increase in richness at 3 months was associated with a 55% reduction in risk for food sensitization by 1 year (adjusted odds ratio 0.45, 95% confidence interval 0.23-0.87). Independently, each quartile increase in Enterobacteriaceae/Bacteroidaceae ratio was associated with a twofold increase in risk (2.02, 1.07-3.80). These associations were upheld in a sensitivity analysis among infants who were vaginally delivered, exclusively breastfed and unexposed to antibiotics. At 1 year, the Enterobacteriaceae/Bacteroidaceae ratio remained elevated among sensitized infants, who also tended to have decreased abundance of Ruminococcaceae. Conclusions and Clinical Relevance Low gut microbiota richness and an elevated Enterobacteriaceae/Bacteroidaceae ratio in early infancy are associated with subsequent food sensitization, suggesting that early gut colonization may contribute to the development of atopic disease, including food allergy. [ABSTRACT FROM AUTHOR]

Primary prevention strategies of allergy so far have been aimed to fight allergy causes, by avoiding risk factors and inhibiting their mechanisms of action. The results of trials testing food or airborne allergen avoidance as a prevention strategy were, however, rather disappointing. A reverse approach for primary prevention of allergies aims to facilitate exposure to protecting factors which promote the induction of immunologic tolerance against innocuous antigens. These factors are associated with farming environment and a ‘traditional lifestyle’, but identification of these factors is quite difficult. Major candidates include food-borne microbes, helminths or their components, which are able to stimulate mucosal immunity, particularly in the gut. Similarly, new preventive and therapeutic strategies are being tested to induce specific food-allergen oral tolerance through the ingestion of progressively increasing doses of the offending food. This shifting of allergy prevention research from avoidance to tolerance induction will hopefully allow us to reverse the epidemic trend of allergy diseases. [ABSTRACT FROM AUTHOR]

Background Mast cells (MCs) are multi-functional effector cells with an essential role in innate immunity and host defence, and under several pathological conditions, such as allergy. Here, we aimed at defining the culture conditions that would allow efficient generation of mature and functional human MCs from their progenitor cells. Methods Human peripheral blood-derived CD34+ progenitor cells were cultured in vitro under serum-free conditions with human stem cell factor for 9 weeks. Growth and differentiation of the cells into MCs were optimized by selected cytokines and a combination of hypoxic and normoxic conditions. MCs were phenotypically characterized by immunocytochemistry, their preformed mediators were quantified, and their functional ability to degranulate and release histamine was tested. Results On average, 20 × 106 mature MCs were generated from 0.5 × 106 progenitor cells during 9 weeks of culture, i.e. at least a 40-fold increase in cell number was achieved. The mature MCs had oval-shaped non-lobular nuclei, contained histamine, heparin, tryptase, chymase, and cathepsin G in their secretory granules, and strongly expressed c-kit (CD117) and Fc epsilon receptor I on their surface. Histamine release from the cells could be brought about by IgE–anti-IgE cross-linkage, compound 48/80, substance P, and anaphylatoxin C3a. The MCs remained functional for several weeks after their maturation. Conclusion This study describes an efficient protocol for generating mature MCs from human peripheral blood with a functional phenotype of connective tissue-type MCs. Use of these cultured human MCs will increase our knowledge and understanding about human MC development and biology in human disease. [ABSTRACT FROM AUTHOR]

CD4+CD25+ regulatory T cells suppress proliferation and cytokine production by human T cells both to self-antigens and exogenous antigens. Absence of these cells in human newborns leads to multiple autoimmune and inflammatory disorders together with elevated IgE levels. However, their role in human allergic disease is still unclear. This study aimed to evaluate the capacity of CD4+CD25+ regulatory T cells to suppress proliferation and cytokine production outside and during birch-pollen season in birch-allergic patients relative to non-allergic controls. CD4+ cells were obtained from blood of 13 birch-allergic patients and six non-allergic controls outside pollen season and from 10 birch-allergic patients and 10 non-allergic controls during birch-pollen season. CD25+ and CD25− fractions were purified with magnetic beads and cell fractions, alone or together in various ratios, were cultured with antigen-presenting cells and birch-pollen extract or anti-CD3 antibody. Proliferation and levels of IFN-γ, IL-13, IL-5 and IL-10 were measured by thymidin incorporation and ELISA, respectively. Numbers of CD25+ cells were analysed by flow cytometry. CD4+CD25+ regulatory T cells from both allergics and non-allergics potently suppressed T cell proliferation to birch allergen both outside and during birch-pollen season. However, during season CD4+CD25+ regulatory T cells from allergic patients but not from non-allergic controls were defective in down-regulating birch pollen induced IL-13 and IL-5 production, while their capacity to suppress IFN-γ production was retained. In contrast, outside pollen season the regulatory cells of both allergics and non-allergic controls were able to inhibit T-helper 2 cytokine production. This is the first study to show differential suppression of Th1 and Th2 cytokines, with CD4+CD25+ regulatory T cells from birch-pollen-allergic patients being unable to down-regulate Th2, but not Th1 responses during birch-pollen season. [ABSTRACT FROM AUTHOR]

Par j 1 represents the major allergenic component of Parietaria judaica pollen. Its three-dimensional structure is stabilized by four disulphide bridges. A family of three-dimensional mutants of the recombinant Par j 1 (rPar j 1) allergen, showing reduced allergenicity and retained T cell recognition has been recently developed by site-directed mutagenesis. To develop and characterize a murine model of IgE sensitization to rPar j 1. To evaluate similarities between the murine model and the human IgE response. To investigate in this model the recognition of a hypoallergenic mutant of Par j 1, and to study the immune responses elicited in mice by the mutant itself. BALB/c mice were sensitized by two intraperitoneal immunizations with rPar j 1 in alum on days 0 and 21. Allergen-specific serum IgE and IgG responses were studied by direct ELISA and immunoblotting, ELISA inhibition and competitive ELISA. Cell proliferation was evaluated in splenocyte cultures. Sensitization with rPar j 1 induced high levels of IgE and IgG1 vs. low levels of IgG2a. Mouse antibodies specific to rPar j 1 were able to compete with human IgE for recognition of rPar j 1. IgE from mice immunized with rPar j 1 showed a significantly reduced binding activity towards the hypoallergenic variant rPjC, which lacks three disulphide bridges. On the contrary, rPjC was recognized by IgG1 and IgG2a antibodies as well as rPar j 1. The proliferative response to rPjC by splenocytes from mice immunized with rPar j 1 was comparable to that stimulated by rPar j 1. Immunization with rPjC induced low levels of IgE antibodies to the rPjC itself, while IgG and proliferative responses were similar to those induced by rPar j 1. Conformational variants of allergens, displaying reduced allergenicity accompanied by retained IgG and T cell recognition, offer a safe, specific and flexible approach to immunotherapy of type I allergy. Our mouse model of IgE sensitization to a recombinant allergen, mimicking the human response to its native counterpart, could provide valuable information for pre-clinical testing of such hypoallergenic molecules. [ABSTRACT FROM AUTHOR]

Hayfever is determined by an interaction of environmental and genetic factors and biologically characterized by an imbalanced T helper cell 1 (Th1) and Th2 immune response and elevated IgE levels against inhalant allergens. Indications exist that polymorphisms in cytokine genes involved in the regulation of the Th1/Th2 balance may contribute to the allergic phenotype. We investigate whether polymorphisms in genes directly or indirectly involved in Th1, Th2 immune response are associated with hayfever and elevated IgE levels against inhalant allergens. From a subsample of the European Prospective Investigation into Cancer and Nutrition-Heidelberg, 322 subjects with hayfever and 322 age- and sex-matched non-allergic controls were selected and genotypes determined for 15 polymorphisms in 13 genes. Plasma IgE against inhalant allergens was measured via CAPSX1 (Phadiatop) test. We computed odds ratios (ORs) by logistic regression, tests on group differences of IgE-levels in dependence upon genotype and tests for trend by means of non-parametric methods. We found decreased OR for hayfever (OR=0.60, 95%CI=0.4–0.9) and sensitization to inhalant antigens (OR=0.5, 95%CI=0.4–0.8) in heterozygotes of the IL-6 −174 G/C polymorphism. Homozygotes of the G-allele in IL-2 −330 T/G were at increased risk of hayfever (OR=2.6, 95%CI=1.3–5.2). Moreover, we found indications for differences in IgE levels against inhalant allergens in dependence upon genotypes of polymorphisms in IL-4R, IL-6, IL-13, and IL-18. Our data suggest an association of genetic variants in IL-6 and IL-2 with hayfever, confirm a role of polymorphisms in IL-4R, IL-13, and IL-18 for the elevated IgE phenotype, and add IL-6 to the list of candidate genes. [ABSTRACT FROM AUTHOR]

Editorial. Discusses the functional diversity of mast cells. Role of mast cells in tissue homeostasis and innate and acquired immunity; Mast cells' location at specific sites within the microenvironment due to their adhesion properties; Use of mast cell culture systems in understanding mast cells.

Background IgE titres tend to rise early after the start of immunotherapy, followed by a decline to pre-immunotherapy levels or lower. Objectives We were interested to know whether the early increase in IgE antibodies includes new specificities of IgE, and whether these responses persist. Methods Sera of 64 patients undergoing grass pollen immunotherapy were tested for IgE against four purified grass pollen allergens: Lol p 1, 2, 3, and 5. At least two serum samples were taken, one before the start of therapy and one between 5 and 18 months after the first immunization (mean: 10 months). Results The mean IgE responses to Lol p 1,2 and 3 showed a moderate but not significant increase. In contrast, the mean IgE response to Lol p 5 showed a significant decrease of >30%. IgE against total Lolium perenne pollen extract moderately increased (>20%), showing that a RAST for total pollen is not always indicative for the development of IgE against its major allergens. For >40% of the patients it was found that IgE against one or more of the four allergens increased, while IgE against the remaining allergen(s) decreased. For 10 sera the ratio of IgE titres against at least two allergens changed by at least a factor of 5. The changes in specific IgE also included conversions from negative (< 0.1 RU) to positive (0.6 to 5.0 RU) for five patients. For two patients, the induction of these 'new' IgE antibodies against major allergens was shown to result in a response that was persistent over several years. Conclusion Although active induction of new IgE specificities by immunotherapy was not really proven, the observations in this study indicate that monitoring of IgE against purified (major) allergens is necessary to evaluate changes in specific IgE in a reliable way. [ABSTRACT FROM AUTHOR]

Background Previous studies on allergy to feathers have not addressed whether organisms living on feathers (mites. lice, moulds) are a source of allergens. Objective To investigate whether feather mites produced allergens of clinical relevance to bird keepers. Methods We examined serum IgE responses of 96 pigeon breeders to an extract of feather mites from pigeons (predominantly Diplaegidia columbae). using Western blotting, specific IgE assay using AlaSTAT EIA and RAST inhibition. Results Feather mites are a major source of soluble proteins derived from feathers, accounting for up to 10% of the total weight of the feather. Forty-three sera had a negative score (0) for anti-feather mite IgE. 27 were weakly positive (1-2) and 26 had strongly positive scores (3-4). Fewer pigeon breeders with scores ⩾ 3 were asymptomatic than those with negative scores (12 versus 40%). more had late onset symptoms (with or without early onset symptoms; 77% versus 44%) and had IgE antibody against house dust mite (89% versus 23%). Western blotting of eight sera against the extract of Diplaegidia columbae revealed 20 IgE-binding components ranging from 22 to 200 kDa. A high diversity of components was recognized by each serum: arithmetic mean 7 (range 2-14). RAST inhibition indicated feather mites had species-specific epitopes as well as ones that cross-reacted with Dermatophagoides pteronyssinus. Conclusion Strongly-positive AlaSTAT scores to pigeon leather mite were associated with allergic symptoms of late onset in pigeon breeders. We conclude that feather mites are a major source of clinically-relevant allergens for pigeon breeders. [ABSTRACT FROM AUTHOR]

Background Allergen avoidance is recommended when treating atopic asthma. Objectives Soft toys are often kept in close proximity to children and may serve as a source of exposure. Due to the potential danger from the mite allergen content of these toys, Der 1 from toys was measured. Methods We quantified the level of Der 1 (Der p 1 + Der f 1) in both 30 new and 174 old soft toys (weight 216 ± 2.5 g, height 26.5 ± 3.4 cm), as well as in washed and in vacuumed soft toys. Dust was collected using an electric vacuum cleaner. Der 1 was measured by monoclonal antibody-based enzyme-linked immunosorbent assay (MoAb-ELISA). Results In brand new toys Der 1 was 0.1 μg/g of dust, and in toys used for 1 year, 9.0; 2 year. 22.2; 3 year, 18.9; and more than 4 year, 22.7 μg/g or dust. Der 1 in new toys was measured every 4 months for 1 year. Der I rapidly increased 10- to 20-fold in the first 4 months, but there was no clear seasonal change. In toys washed using a chemical detergent or cleaned using a vacuum cleaner, there was a stastistically significant (P<0.001) decrease in Der I in the washed group, but not in the vacuumed group. Conclusion These results confirm that mite allergens accumulate rapidly in toys to form a potentially important source of allergens and that washing toys with a chemical detergent is effective in the reduction of allergens. [ABSTRACT FROM AUTHOR]

Background Allergy to rats is an important occupational health problem. The allergens of rat urine have been well defined but those in rat room dust, a potentially important source of inhalant exposure, have not. Objective To describe the allergens present in rat room dust and to identify a suitable marker protein which may be used to quantify airborne rat allergen. Methods Dust collected from the air-conditioning system (bulk dust, ‘bd’) and with an air sampler (airborne dust, ‘ad’) were analysed by radioallergosorbent test (RAST) inhibition, immunoblotting and immunoblot inhibition techniques and comparisons made with hair and urine extracts prepared from adult male Wistar rats. Results Extensive crossreactivity was found between the extracts by RAST inhibition under different experimental conditions. Dust was more potent as an inhibitor than other extracts. The immunoblotting patterns of both dusts were similar although ‘ad’ contained an allergen at 29 kDa not found in ‘bd’. Forty-two sera from rat allergic subjects were used to identify 18 allergens in ‘bd’→. Three ‘major’ allergens were found; 100% of subjects had immunoglobulin (Ig)E to a 44 kDa allergen and 74% and 88% of subjects had IgE with bound to the 20.5 and 17 kDa allergens respectively. Immunoblot inhibition experiments identified the 17 kDa dust allergen as α2u-globulin (Rat nI). Conclusions Rat dust is a complex allergenic source. The 17 kDa dust allergen has immunological identity with Rat nI and is a suitable marker protein for the quantitation of airborne rat allergen. [ABSTRACT FROM AUTHOR]

Summarizes the important aspects of allergy research work on purified allergens. Denominations of allergens; Relation of everyday life with exposure to an enormous number of potential allergens in the environment; Identification and characterization of allergens.

Examines the effectiveness of allergens as means of treating rhinitis. Potential in reducing rhinitic symptoms; Impact of the introduction of recombinant DNA techniques on the structure and variability of the allergens; Identification of multiple T cell epitopes on Bet V.

The non-pyroglyphid domestic mite Lepidoglyphus destructor is a major source of allergen causing respiratory symptoms in farming environments. This study is the first to focus on the localization of the allergens in the non-pyroglyphid domestic mite Lepidoglyphus destructor. Cryostat-cut sections of L. destructor mite bodies and faecal pellets were probed with one of three mouse monoclonal antibodies (MoAbs) raised against L. destructor or with patient sera, and stained with immunoperoxidase. Eight sera were RAST-positive to L. destructor and L. destructor faecal pellets. These eight RAST-positive patient sera labelled the wall of the L. destructor gut and two of them also the faecal pellets. The MoAbs additionally labelled parts of the exoskeleton and reacted with a majority of the faecal pellets. Cryostat-cut sections of Dermatophagoides pteronyssinus mite bodies and faecal pellets were probed with L. destructor MoAbs, which resulted in only slight staining of a few faecal pellets. The results suggest that at least one L. destructor allergen is associated with digestion. [ABSTRACT FROM AUTHOR]

In the present investigation we have tested the hypothesis that children with a high IgG antibody response to foods have an increased risk of developing IgE antibodies to inhalant allergens. Sera from 106 children with an increased risk of developing IgE-mediated allergy were analysed. During the follow-up, in 54 of these children IgE antibodies to inhalant allergens appeared. A positive/negative IgG1 and IgG4 anti-food score was determined as described previously: sera from age-clustered unselected children were tested for the levels of IgG1 and IgG4 antibodies to common foods. For each IgG RAST and each age group, the 75-percentile was chosen as cut-off value. Each antibody level was thus converted into a positive (higher than the 75-percentile of the age group) or negative value. The number of positive tests was used as the score. High-risk children with a high IgG1 anti-food score more often developed inhalant-specific IgE antibodies than high-risk children with low IgG1 titres: 50% of the children with a high IgG1 anti-food score developed IgE antibodies to grass pollen, whereas only 16% of the children with a low IgG1 anti-food score acquired IgE anti-grass pollen. Fifty percent of the children with a high and 14% of the children with a low IgG1 anti-food score developed IgE antibodies to cat dander. For the prediction of the development of IgE anti-mite(house dust mite), the IgG4 anti-food scores appeared less useful than the IgG1 anti-food scores; 46% of the IgG4 high responders versus 22% of the IgG4 low responders acquired IgE anti-mite, whereas for IgG1 these precentages were 73 and 19, respectively. [ABSTRACT FROM AUTHOR]

To obtain reference levels for subsequent investigations, we analysed the IgG1 and IgG4 antibody levels to common foods in the sera of 213 unselected children (age 3 months to 14 years). The children were clustered into five age groups and tested on a broad screening panel of common foods. We used the IgG1 and IgG4 RAST with Sepharose-coupled antigens: cows' milk, hens' egg white, banana, legumes (a mixture of soybean and peanut), grains (a mixture of wheat and rice), potato, orange and pork. In all age groups and all antigens, a considerable variability in the antibody response was found. As for some assays more than half of the sera were negative or borderline, statistics based on interval or ordinal scaling were considered inappropriate and we resorted to nominal classification. We decided to use, for each of the assays, the 75-percentile of the age group as a cut-off level. Each antibody titre was thus converted into positive (more than the 75-percentile of that age group) or negative; the number of positive tests was used as the score. This resulted in a ΣG1-score and a ΣG4 score (summed scores for IgG1 and IgG4 antibodies, respectively). The results of the present study indicate that children with a high response to one food tend to have elevated responses to other non-related foods, possibly explained by a defective mucosal barrier and/or a hyperactive immune system. This suggests that a high-food responder phenotype may exist. [ABSTRACT FROM AUTHOR]

Fragments of short ragweed extract were prepared by peptic digestion and fractionated by molecular exclusion chromatography. We focused on fragmenting a ragweed fraction that was enriched for Amb al. Digestion products in themolecular weight range of 5–15 kD (fSRW) were examined for their antigenic, immunogenic and immunosuppressive properties. fSRW was poorly immunogenic and unable to induce ragweed-specific PCA reactions in rat skin or to bind to anti-ragweed IgG antibodies. Intravenous administration of f SRW either prior to or after intraperitoneal immunization with a ragweed preparation resulted in a significant suppression of the immune response. T cells isolated from lymph nodes of mice immunized with ragweed were stimulated by fSRW in a lymphoproliferation assay. Moreover, T cells from mice injected with fSRW were immunosuppressive when transferred into mice immunized with intact ragweed antigens. Our data demonstrate that peptic fragments (fSRW) of ragweed lack B-cell determinants while retaining their T-cell immunoregulatory properties. Potentially these peptides are less likely to cause adverse reactions in allergen sensitive patients and thus offer a new approach to allergen immunotherapy. [ABSTRACT FROM AUTHOR]

The author reflects on the study by N. Følsgaard and colleagues regarding the utilization of chemokines as indicators of immune status and its relationship with development of allergic disorders and clinical phenotypes in the first six years of life. He argues that chemokines offer easy analysis of immune and immunoregulatory status and feature ease and reproducibility of detection. He states that the study could result to increase identification of biomarkers.

The article focuses on a study which describes a model of antigen challenge in sensitized mice, in which the presumably IL-5-dependent lung eosinophilia is divorced from antigen-induced changes in airway responsiveness. A similar claim has been made for a dissociation of airway responsiveness and bronchoalvolar lavage cell composition in sensitized guinea-pigs. This study showed that the antibody to IL-5 prevented lung eosinophilia without affecting bronchial hyperresponsiveness, while mast cells appeared to play an important role in the onset of hyperresponsiveness but did not play a role in the production of IL-5 and eosinophilia.