Allergenicity of Ascaris lumbricoides tropomyosin and IgE sensitization among asthmatic patients in a tropical environment

Toward Consensus Epitopes B and T of Tropomyosin Involved in Cross-Reactivity across Diverse Allergens: An In Silico Study

Tropomyosin (TM) is a pan-allergen with cross-reactivity to arthropods, insects, and nematodes in tropical regions. While IgE epitopes of TM contribute to sensitization, T-cell (MHC-II) epitopes polarize the Th2 immune response. This study aimed to identify linear B and T consensus epitopes among house dust mites, cockroaches, Ascaris lumbricoides, shrimp, and mosquitoes, exploring the molecular basis of cross-reactivity in allergic diseases. Amino acid sequences of Der p 10, Der f 10, Blo t 10, Lit v 1, Pen a 1, Pen m 1, rAsc l 3, Per a 7, Bla g 7, and Aed a 10 were collected from Allergen Nomenclature and UniProt. B epitopes were predicted using AlgPred 2.0 and BepiPred 3.0. T epitopes were predicted with NetMHCIIpan 4.1 against 10 HLA-II alleles. Consensus epitopes were obtained through analysis and Epitope Cluster Analysis in the Immune Epitope Database. We found 7 B-cell epitopes and 28 linear T-cell epitopes binding to MHC II. A unique peptide (residues 160-174) exhibited overlap between linear B-cell and T-cell epitopes, highly conserved across tropomyosin sequences. These findings shed light on IgE cross-reactivity among the tested species. The described immuno-informatics pipeline and epitopes can inform in vitro research and guide synthetic multi-epitope proteins' design for potential allergology immunotherapies. Further in silico studies are warranted to confirm epitope accuracy and guide future experimental protocols.

Cystatin from the helminth Ascaris lumbricoides upregulates mevalonate and cholesterol biosynthesis pathways and immunomodulatory genes in human monocyte-derived dendritic cells

Background

Ascaris lumbricoides cystatin (Al-CPI) prevents the development of allergic airway inflammation and dextran-induced colitis in mice models. It has been suggested that helminth-derived cystatins inhibit cathepsins in dendritic cells (DC), but their immunomodulatory mechanisms are unclear. We aimed to analyze the transcriptional profile of human monocyte-derived DC (moDC) upon stimulation with Al-CPI to elucidate target genes and pathways of parasite immunomodulation.

Methods

moDC were generated from peripheral blood monocytes from six healthy human donors of Denmark, stimulated with 1 µM of Al-CPI, and cultured for 5 hours at 37°C. RNA was sequenced using TrueSeq RNA libraries and the NextSeq 550 v2.5 (75 cycles) sequencing kit (Illumina, Inc). After QC, reads were aligned to the human GRCh38 genome using Spliced Transcripts Alignment to a Reference (STAR) software. Differential expression was calculated by DESEq2 and expressed in fold changes (FC). Cell surface markers and cytokine production by moDC were evaluated by flow cytometry.

Results

Compared to unstimulated cells, Al-CPI stimulated moDC showed differential expression of 444 transcripts (|FC| ≥1.3). The top significant differences were in Kruppel-like factor 10 (KLF10, FC 3.3, PBH = 3 x 10-136), palladin (FC 2, PBH = 3 x 10-41), and the low-density lipoprotein receptor (LDLR, FC 2.6, PBH = 5 x 10-41). Upregulated genes were enriched in regulation of cholesterol biosynthesis by sterol regulatory element-binding proteins (SREBP) signaling pathways and immune pathways. Several genes in the cholesterol biosynthetic pathway showed significantly increased expression upon Al-CPI stimulation, even in the presence of lipopolysaccharide (LPS). Regarding the pathway of negative regulation of immune response, we found a significant decrease in the cell surface expression of CD86, HLA-DR, and PD-L1 upon stimulation with 1 µM Al-CPI.

Conclusion

Al-CPI modifies the transcriptome of moDC, increasing several transcripts encoding enzymes involved in cholesterol biosynthesis and SREBP signaling. Moreover, Al-CPI target several transcripts in the TNF-alpha signaling pathway influencing cytokine release by moDC. In addition, mRNA levels of genes encoding KLF10 and other members of the TGF beta and the IL-10 families were also modified by Al-CPI stimulation. The regulation of the mevalonate pathway and cholesterol biosynthesis suggests new mechanisms involved in DC responses to helminth immunomodulatory molecules.

The Relationship of Parasite Allergens to Allergic Diseases

PURPOSE OF REVIEW

Helminth infections modify the natural history of allergic diseases, by either decreasing or increasing their symptoms. Several helminth components are involved in the increasing of the allergic response and symptoms, overcoming the concomitant immunosuppression of helminthiases. However, the role of individual IgE-binding molecules in this process remains to be defined.

RECENT FINDINGS

We updated the list of helminth allergens and IgE-binding molecules, their effects on asthma presentation, and their impact on allergy diagnosis. Data from genetic and epigenetic studies of ascariasis are analyzed. A new species-specific A. lumbricoides allergen has been discovered, with potential use in molecular diagnosis. Most helminth IgE-binding components are not officially classified as allergens in the WHO/IUIS database, although there is evidence of their influence increasing allergic manifestations. Further immunological characterization of these components is needed to better understand their mechanisms of action and evaluate the ways in which they can influence the diagnosis of allergy.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Multiple overlapping risk factors for childhood wheeze among children in Benin

BACKGROUND

The African continent is currently facing an epidemiological transition characterized by a shift from communicable to non-communicable diseases. Prominent amongst the latter are allergies and asthma. In that context, wheeze has multiple potential contributory factors that could include some of the endemic helminth infections, as well as environmental exposures, such as household air pollution. We sought to determine the relative importance of these risk factors among children in Benin.

METHODS

We included 964 children aged 6-14 years living in the commune of Comé, south-west Benin. All children were participants in the longitudinal monitoring cohort of the DeWorm3 trial designed to evaluate multiple rounds of community mass treatment with albendazole for interruption of the transmission of soil transmitted helminths (STH). We administered a standard ISAAC questionnaire to determine the presence of wheeze. In addition, we assessed exposure to household air pollution and to other potential allergy-inducing factors, dietary intake and anthropometry. Using STH infection status assessed at the pretreatment baseline timepoint, we used multivariate statistical modelling, controlling for covariates, to investigate associations between wheeze and the different factors measured.

RESULTS

The prevalence of wheezing history was 5.2%, of current wheezing was 4.6% and of severe wheezing was 3.1%, while STH infections were found in 5.6% of children. These profiles did not vary as a function of either age or gender. Infection with Ascaris lumbricoides, but not hookworm species, was significantly associated with both current wheeze (adjusted Odds Ratio (aOR) = 4.3; 95% CI [1.5-12.0]) and severe wheeze (aOR = 9.2; 95% CI [3.1-27.8]). Significant positive associations with current wheeze, independent of each other and of STH infection status, were also found for (i) use of open cookstoves (aOR = 3.9; 95% CI [1.3-11.5]), (ii) use of palm cakes for fire lighting (aOR = 3.4; 95% CI [1.1-9.9]), (iii) contact with domestic animals and/or rodents (aOR = 2.5; 95% CI [1.1-6.0]), (iv) being overweight (aOR = 9.7; 95% CI [1.7-55.9]). Use of open cookstoves and being overweight were also independent risk factors for severe wheeze (aOR = 3.9; 95% CI [1.1-13.7]) and aOR = 10.3; 95% CI [1.8-60.0], respectively).

CONCLUSIONS

Children infected with A. lumbricoides appear to be at elevated risk of wheeze. Deworming may be an important intervention to reduce these symptoms. Improving cooking methods to reduce household air pollution, modifying dietary habits to avoid overweight, and keeping animals out of the house are all additional measures that could also contribute to reducing childrens' risk of wheeze. Policymakers in LMIC should consider tailoring public health measures to reflect the importance of these different risk factors.

Unbalanced relationships: insights into the interaction between gut microbiota, geohelminths, and schistosomiasis

Hosts and their microbiota and parasites have co-evolved in an adaptative relationship since ancient times. The interaction between parasites and intestinal bacteria in terms of the hosts' health is currently a subject of great research interest. Therapeutic interventions can include manipulations of the structure of the intestinal microbiota, which have immunological interactions important for modulating the host's immune system and for reducing inflammation. Most helminths are intestinal parasites; the intestinal environment provides complex interactions with other microorganisms in which internal and external factors can influence the composition of the intestinal microbiota. Moreover, helminths and intestinal microorganisms can modulate the host's immune system either beneficially or harmfully. The immune response can be reduced due to co-infection, and bacteria from the intestinal microbiota can translocate to other organs. In this way, the treatment can be compromised, which, together with drug resistance by the parasites makes healing even more difficult. Thus, this work aimed to understand interactions between the microbiota and parasitic diseases caused by the most important geohelminths and schistosomiasis and the consequences of these associations.

Risk Factors Associated With Health Care Utilization in Preschool Recurrent Wheezers in a Tropical Environment

Introduction: The severity of wheezing episodes is related with the need for health services, but the factors associated with health care utilization in preschool recurrent wheezers in underdeveloped regions are unclear.

Objective: To evaluate the factors associated with health care utilization in preschool recurrent wheezers in Cartagena, Colombia.

Methods: One hundred twenty-seven recurrent wheezers (age 2–6 years old) who were admitted to the emergency room (ER) due to wheezing in a Pediatric reference hospital in Cartagena were included. Children were evaluated by means of questionnaires and classified according to the number of ER visits, need for hospitalization and history of intensive care unit (ICU) admission due to wheezing within the last year. Total serum IgE and specific IgE to house dust mite allergens (HDM) were measured by ImmunoCAP® and allergen sensitization was evaluated by skin prick tests (SPT).

Results: The maternal report of nocturnal cough without fever in their children increased the risk to have ≥5 ER visits in the last year due to wheezing. The use of montelukast was negatively associated with hospitalization, while a history of pneumonia and lack of tap water, increased the risk of hospitalization due to wheezing. A history of bronchiolitis, family history of asthma, cohabiting with two or more siblings, passive exposure to smoke and lack of sewage facilities increased the risk of ICU admission due to wheezing. The presence of atopy evaluated by SPT reactivity, total IgE levels or specific IgE to HDM were not associated with health care utilization. We also found that seroprevalence of positive IgE (≥0.35 kU/L) was 27% to B. tropicalis and 20.3% to D. pteronyssinus but the prevalence of positive IgE sensitization to these allergens was below 2% and 8% when evaluated by SPT, respectively.

Conclusions: Poverty indicators are associated with ICU admission in a group of preschool recurrent wheezers and should be considered as aggravating factors for wheezing. These factors must be systematically assessed in the medical approach in underdeveloped regions in the tropics. Nocturnal cough without fever is a symptom associated with frequent ER visits while atopy was not associated with health care utilization in preschool recurrent wheezers.

Ascaris lumbricoides and ticks associated with sensitization to galactose α1,3-galactose and elicitation of the alpha-gal syndrome

BACKGROUND

IgE to galactose alpha-1,3 galactose (alpha-gal) causes alpha-gal syndrome (delayed anaphylaxis after ingestion of mammalian meat). Development of sensitization has been attributed to tick bites; however, the possible role of other parasites has not been well studied.

OBJECTIVE

Our aims were to assess the presence, relative abundances, and site of localization of alpha-gal-containing proteins in common ectoparasites and endoparasites endemic in an area of high prevalence of alpha-gal syndrome, as well as to investigate the ability of ascaris antigens to elicit a reaction in a humanized rat basophil in vitro sensitization model.

METHODS

Levels of total IgE, Ascaris-specific IgE, and alpha-gal IgE were measured in sera from patients with challenge-proven alpha-gal syndrome and from controls without allergy. The presence, concentration, and localization of alpha-gal in parasites were assessed by ELISA, Western blotting, and immunohistochemistry. The ability of Ascaris lumbricoides antigen to elicit IgE-dependent reactivity was demonstrated by using the RS-ATL8 basophil reporter system.

RESULTS

Alpha-gal IgE level correlated with A lumbricoides-specific IgE level. Alpha-gal protein at 70 to 130 kDa was detected in A lumbricoides at concentrations higher than those found in Rhipicephalus evertsi and Amblyomma hebraeum ticks. Immunohistochemistry was used to localize alpha-gal in tick salivary acini and the helminth gut. Non-alpha-gal-containing A lumbricoides antigens activated RS-ATL8 basophils primed with serum from subjects with alpha-gal syndrome.

CONCLUSION

We demonstrated the presence, relative abundances, and site of localization of alpha-gal-containing proteins in parasites. The activation of RS-ATL8 IgE reporter cells primed with serum from subjects with alpha-gal syndrome on exposure to non-alpha-gal-containing A lumbricoides proteins indicates a possible role of exposure to A lumbricoides in alpha-gal sensitization and clinical reactivity.

Allergens from Edible Insects: Cross-reactivity and Effects of Processing

PURPOSE OF REVIEW

The recent introduction of edible insects in Western countries has raised concerns about their safety in terms of allergenic reactions. The characterization of insect allergens, the sensitization and cross-reactivity mechanisms, and the effects of food processing represent crucial information for risk assessment.

RECENT FINDINGS

Allergic reactions to different insects and cross-reactivity with crustacean and inhalant allergens have been described, with the identification of new IgE-binding proteins besides well-known pan-allergens. Depending on the route of sensitization, different potential allergens seem to be involved. Food processing may affect the solubility and the immunoreactivity of insect allergens, with results depending on species and type of proteins. Chemical/enzymatic hydrolysis, in some cases, abolishes immunoreactivity. More studies based on subjects with a confirmed insect allergy are necessary to identify major and minor allergens and the role of the route of sensitization. The effects of processing need to be further investigated to assess the risk associated with the ingestion of insect-containing food products.

Correlation of Total IgE Level and Intensity of Infection among Soil Transmitted Helminthiasis Farmers in Klungkung Regency, Bali, Indonesia

The phenomena of increasing total IgE level in Soil Transmitted Helminthiasis and its protective role in resistance of infection remains unclear. The purpose of this study was to determine the correlation between total IgE and the intensity of Soil transmitted helminthiasis among farmers in these area. Total 162 farmer, age ranged 25-80 years participated in this cross sectional analytic study. Kato-Katz method was used to diagnose Soil Transmitted Helminthiasis and to determined infection intensity based on egg per gram (EPG). Total IgE levels were measured by enzyme linked flourescent assay (ELFA). The results of this study showed that 13,56% farmer positive  for Soil Transmitted Helminthiasis, with single infection of Ascaris lumbricoides were 1,85%, 9,26% for Trichuris trichiura, 0,61% for Hookworm and mixed infection that were 1,23% for A.lumbricoides+T.trichiura 0,61%  for A.lumbricoides+Hookworm. The intensity of infection were in mild category. Total IgE level in Soil transmitted Helminthiasis group was significantly different compared with noninfected group (p<0.05, t-test). There was significant correlation between EPG and total IgE level (r=0.667, p=0.001, Spearman test). As a conclusion total IgE level was significantly correlated with EPG, this fact can be used to develop management of Soil Transmitted Helminthiasis theraphy.

Identification and Physicochemical Characterization of a New Allergen from Ascaris lumbricoides

To analyze the impact of Ascaris lumbricoides infection on the pathogenesis and diagnosis of allergic diseases, new allergens should be identified. We report the identification of a new Ascaris lumbricoides allergen, Asc l 5. The aim of this study was to evaluate the physicochemical and immunological features of the Asc l 5 allergen. We constructed an A. lumbricoides cDNA library and Asc l 5 was identified by immunoscreening. After purification, rAsc l 5 was physicochemically characterized. Evaluation of its allergenic activity included determination of Immunoglobulin E (IgE) binding frequency (in two populations: 254 children and 298 all-age subjects), CD203c based-basophil activation tests (BAT) and a passive cutaneous anaphylaxis (PCA) mouse model. We found by amino acid sequence analysis that Asc l 5 belongs to the SXP/RAL-2 protein family of nematodes. rAsc l 5 is a monomeric protein with an alpha-helical folding. IgE sensitization to rAsc l 5 was around 52% in general population; positive BAT rate was 60%. rAsc l 5 induced specific IgE production in mice and a positive PCA reaction. These results show that Asc l 5 has structural and immunological characteristics to be considered as a new allergen from A. lumbricoides.

Cellular immune response of asthmatic children in the presence of anti-Ascaris antibody

The presence of anti-Ascaris (anti-Asc) immunoglobin isotypes alters the risk of allergic asthma. In this study, we analyzed the relationships between serum levels of anti-Asc IgE, IgG1, and IgG4, without concurrent infection by the parasite, and the presence of asthma. We measured cytokine levels from Th1, Th2, and Th17 profiles. Children aged 2-14 years old, asthmatics (n = 64), and non-asthmatics (n = 40) were selected according to the International Study of Asthma and Allergies in Childhood criteria. Asthmatic patients who had positive skin allergy tests were considered to have allergic asthma. Stool exams were performed to exclude children who were parasitized by helminths/protozoans and blood samples were collected in non-parasitized individuals. We performed peripheral blood leukocyte counts and in vitro culture following mitogenic stimulation. Levels of cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ, and IL-17) in the supernatants were measured using a cytometric bead array. Titration of serum total IgE and IgE specific to Ascaris were obtained using ImmunoCAP; IgG1 and IgG4 titers were measured using enzyme-linked immunosorbent assays. Anti-Asc IgE was associated with a higher risk of asthma and an increase in the number of eosinophils and neutrophils. By contrast, anti-Asc IgG1 could be considered a protective factor against asthma, associated with lower levels of circulating neutrophils. There were high levels of IL-6 and TNF-α in asthmatics. Levels of IL-6, but not TNF-α, depended on the presence of anti-Asc IgG1 in serum. Anti-Asc IgE appears to increase risk of asthma, and anti-Asc IgG1 appears to favor decreased neutrophil counts and increased IL-6 levels.

Personalized medicine for asthma in tropical regions

PURPOSE OF REVIEW

Precision medicine could help to improve diagnosis and treatment of asthma; however, in the tropics there are special conditions to be considered for applying this strategy. In this review, we analyze recent advances of precision allergology in tropical regions, highlighting its limitations and needs in high-admixed populations living under environments with high exposure to house dust mites and helminth infections.

RECENT FINDINGS

Advances have been made regarding the genetic characterization of the great diversity of populations living in the tropics. Genes involved in shared biological pathways between immune responses to nematodes and the allergic responses suggested new mechanisms of predisposition. Genome wide association studies of asthma are progressively focusing on some highly replicated genes such as those in chromosome 17q31-13, which have been also replicated in African ancestry populations. Some diagnostic difficulties, because of the endemicity of helminth infections, are now more evident in the context of phenotype definition.

SUMMARY

The clinical impact of the advances in precision medicine for asthma in the tropics is still limited and mainly related to component resolved diagnosis. More basic and clinical research is needed to identify genetic, epigenetic, or other biologic markers that allow and accurate definition of phenotypes and endotypes of this heterogeneous disease. This will substantially improve the selection of personalized treatments.

The allergenic activity and clinical impact of individual IgE-antibody binding molecules from indoor allergen sources

A large number of allergens have been discovered but we know little about their potential to induce inflammation (allergenic activity) and symptoms. Nowadays, the clinical importance of allergens is determined by the frequency and intensity of their IgE antibody binding (allergenicity). This is a rather limited parameter considering the development of experimental allergology in the last 20 years and the criteria that support personalized medicine. Now it is known that some allergens, in addition to their IgE antibody binding properties, can induce inflammation through non IgE mediated pathways, which can increase their allergenic activity. There are several ways to evaluate the allergenic activity, among them the provocation tests, the demonstration of non-IgE mediated pathways of inflammation, case control studies of IgE-binding frequencies, and animal models of respiratory allergy. In this review we have explored the current status of basic and clinical research on allergenic activity of indoor allergens and confirm that, for most of them, this important property has not been investigated. However, during recent years important advances have been made in the field, and we conclude that for at least the following, allergenic activity has been demonstrated: Der p 1, Der p 2, Der p 5 and Blo t 5 from HDMs; Per a 10 from P. americana; Asp f 1, Asp f 2, Asp f 3, Asp f 4 and Asp f 6 from A. fumigatus; Mala s 8 and Mala s 13 from M. sympodialis; Alt a 1 from A. alternata; Pen c 13 from P. chrysogenum; Fel d 1 from cats; Can f 1, Can f 2, Can f 3, Can f 4 and Can f 5 from dogs; Mus m 1 from mice and Bos d 2 from cows. Defining the allergenic activity of other indoor IgE antibody binding molecules is necessary for a precision-medicine-oriented management of allergic diseases.

Parasite Infections, Allergy and Asthma: A Role for Tropomyosin in Promoting Type 2 Immune Responses

INTRODUCTION

The relationship of parasite infections and promotion or protection from allergy and asthma is controversial. Currently, over 1.5 billion people are infected with parasites worldwide, and Ascaris lumbricoides is the most frequent soil-transmitted helminth.

OBJECTIVES

To evaluate the biological activity of recombinant A. lumbricoides tropomyosin and investigate IgE cross-reactive responses to tropomyosins by means of microarray methodology for the detection of sensitization to allergen components.

METHODS

Forty patients 12-75 years of age (25 males) with asthma and/or rhinitis and 10 nonallergic control subjects participated in this study. All patients presented positive skin tests to cockroach extracts and underwent skin prick testing (SPT) with recombinant (r) tropomyosins rPer a 7 from Periplaneta americana and rAsc l 3 from A. lumbricoides, at 10 μg/mL. IgE to cockroach and parasite tropomyosins were measured by chimeric ELISA and ImmunoCAP-ISAC, and total IgE was quantitated by ImmunoCAP. Agreement of results was assessed by κ statistics.

RESULTS

Recombinant A. lumbricoides showed biological activity, inducing positive skin tests in 50% patients with asthma and/or rhinitis. IgE to cockroach and parasite tropomyosins were detected in 55-62% of patients. There was good-to-excellent agreement of results of SPT and IgE measurements by ELISA and ImmunoCAP-ISAC, with κ indices of 0.66-0.95. No skin test reactivity or IgE antibodies to tropomyosins were found in nonallergic individuals.

CONCLUSIONS

Our results suggest that IgE responses to tropomyosin from A. lumbricoides may enhance reactivity to homologous allergens upon exposure by inhalation or ingestion, promoting allergic reactions and asthma, or increasing the severity of these clinical conditions.

Classification of Wheezing Children in Rural Bangladesh by Intensity of Ascaris Infection, Total and Specific IgE Levels, History of Pneumonia, and Other Risk Factors

Ascaris lumbricoides is the most common soil-transmitted helminth and infects 447 million people in impoverished areas worldwide. It causes serious morbidity including wheezing and influences various aspects of human immunity, such as type 2 innate lymphoid cells, regulatory T cell function, and acquired immunity. Thus, it is crucial to elucidate its influence on human immunity. We aimed to classify wheezing children based on their Ascaris infection intensity and other risk factors using hierarchical cluster analysis to determine the mechanisms of and the degree to which Ascaris contributes to childhood wheezing in rural Bangladesh. We analyzed relevant data collected in 2001. The participants included 219 5-year-old wheezing children who were randomly selected from 1705 children living in the Matlab Health and Demographic Surveillance area of the International Centre for Diarrhoeal Disease Research, Bangladesh. Hierarchical cluster analysis was conducted using variables of history of pneumonia, total and specific immunoglobulin E levels, Ascaris infection intensity, and parental asthma. Three distinct wheezing groups were identified. Children in Cluster 1 (n = 50) had the highest titers of the total, anti-Ascaris, anti-Dermatophagoides pteronyssinus, and anticockroach IgEs and experienced the fewest episodes of pneumonia. Cluster 2 (n = 114), the largest group, experienced few episodes of pneumonia and had the lowest titers of the total, anti-Ascaris, anti-Dp, and anticockroach IgEs. Cluster 3 (n = 32) consisted of participants with the most episodes of pneumonia and lower titers of the total and specific IgEs. The extremely high prevalence of Ascaris infection found in Clusters 1-3 was 78%, 77%, and 72%, respectively. Childhood wheezing in rural Bangladesh could be divided into three groups, with 26% of wheezing attributable to anti-Ascaris IgE and 16% to history of pneumonia during early childhood, and 58% might have been due to Ascaris infection without elevated anti-Ascaris IgE.

Concurrent decreases in the prevalence of wheezing and Ascaris infection among 5-year-old children in rural Bangladesh and their regulatory T cell immunity after the implementation of a national deworming program

INTRODUCTION

Epidemiological research on the prevalence of asthma and helminthic infections in various countries has led to the hypothesis that helminthic infections protect against asthma by suppressing the host's immune response. This study was conducted to elucidate whether decreased Ascaris infection following a national deworming program was associated with increased recurrent wheezing among rural Bangladeshi children and to test their anti-inflammatory immunity.

METHODS

This nested case-control study was conducted from December 2015 to October 2016 in the rural service area of the International Centre for Diarrhoeal Disease Research, Bangladesh. Of the 1800 5-year old children randomly selected for the study, informed consent was obtained from the guardians of 1658 children. Data were collected using a semistructured questionnaire adopted from the International Study of Asthma and Allergies in Childhood and blood samples for the analysis of regulatory T (Treg) cell immune responses and the balance between Th1 and Th2 immunity in Ascaris infections.

RESULTS

A total of 145 children were found to have wheezing, yielding a prevalence rate of 8.7%, which was significantly lower than the rate found in 2001 (16.2%, P < .001); Ascaris infection also decreased from 2001 to 2016. The 127 wheezing children who agreed to participate further were compared to 114 randomly selected never-wheezing children. Wheezing had a significant positive association with antibiotic use, history of pneumonia, parents' history of asthma, and Ascaris infection; children with Ascaris infection were twice as likely to have wheezing (adjusted odds ratio = 2.31, P = .053). Flow cytometry found no significant differences in the rates of Th1, Th2, and CD4 + CD25 + CD127low cells by the wheezing group.

CONCLUSIONS

Ascaris infection had a positive rather than a negative association with wheezing and the rates of wheezing and Ascaris infections both decreased from 2001 to 2016. These findings undermines the hypothesis that such infections provide protection against asthma.

Hygienic conditions influence sensitization to Blomia tropicalis allergenic components: Results from the FRAAT birth cohort

BACKGROUND

In tropical zones, perennial exposure to house dust mite (HDM) allergens and helminth infections is present. Studying the impact of these conditions on the inception and evolution of allergic diseases is necessary to have an accurate view of their natural history. We aimed to evaluate the dynamics of genuine sensitization to Blomia tropicalis and Ascaris in children from the FRAAT birth cohort and the effects of helminth infection, environmental HDM allergen levels, and sociodemographic factors.

METHODS

Children were followed up to 6 years old. Specific IgE to recombinant allergens from B. tropicalis (Blo t 5 and Blo t 12) and Ascaris spp (Asc l 3, Asc l 13 and Asc s 1) was measured by ELISA at different time points. Allergen levels were measured in dust when children were 6 months old.

RESULTS

IgE sensitization increased over time up to 3 years old. Correlation among the specific IgE levels to B. tropicalis and Ascaris components is poor at year 1, but coefficients are high and significant (Spearman's rho coefficients >0.70) at year 6. Unhygienic conditions increased the odds of sensitization to B. tropicalis allergenic components. Blo t 5 levels were lower in the poorest. IgE response to Blo t 5 and Blo t 12 was less intense in children with high exposure to Blo t 5 (levels >80th percentile).

CONCLUSION

In this tropical community, the pattern of childhood IgE sensitization is different from that in developing countries and is influenced by the hygienic conditions.

House Dust Mite Allergy Under Changing Environments

Environmental variations induced by industrialization and climate change partially explain the increase in prevalence and severity of allergic disease. One possible mechanism is the increase in allergen production leading to more exposure and sensitization in susceptible individuals. House dust mites (HDMs) are important sources of allergens inducing asthma and rhinitis, and experimentally they have been demonstrated to be very sensitive to microenvironment modifications; therefore, global or regional changes in temperature, humidity, air pollution or other environmental conditions could modify natural HDM growth, survival and allergen production. There is evidence that sensitization to HDMs has increased in some regions of the world, especially in the subtropical and tropical areas; however, the relationship of this increase with environmental changes is not so clear as has reported for pollen allergens. In this review, we address this point and explore the effects of current and predicted environmental changes on HDM growth, survival and allergen production, which could lead to immunoglobulin E (IgE) sensitization and allergic disease prevalence. We also assess the role of adjuvants of IgE responses, such as air pollution and helminth infections, and discuss the genetic and epigenetic aspects that could influence the adaptive process of humans to drastic and relatively recent environmental changes we are experiencing.

Ascariasis as a model to study the helminth/allergy relationships

Ascariasis is the most frequent soil transmitted helminthiasis and, as well as other helminth infections, is expected to influence the clinical presentation of allergic diseases such as asthma. Indeed, several clinical and experimental works have shown an important impact either increasing or suppressing symptoms, and the same effects have been detected on the underlying immune responses. In this review we analyze the work on this field performed in Colombia, a Latin American tropical country, including aspects such as the molecular genetics of the IgE response to Ascaris; the allergenic activity of Ascaris IgE-binding molecular components and the immunological and clinical influences of ascariasis on asthma. The analysis allows us to conclude that the impact of ascariasis on the inception and evolution of allergic diseases such as asthma deserves more investigation, but advances have been made during the last years. The concurrent parasite-induced immunostimulatory and immunosuppressive effects during this helminthiasis do modify the natural history of asthma and some aspects of the practice of allergology in the tropics. Theoretically it can also influence the epidemiological trends of allergic diseases either by its absence or presence in different regions and countries.

Ascaris lumbricoides infection induces both, reduction and increase of asthma symptoms in a rural community

Several studies, in different populations and environments, have shown that severe and light helminthiases diminish and increase allergy symptoms, respectively. However, data on the simultaneous presence of these contrary effects in a single community is lacking. In a rural community from Colombia, effects of helminthiases on allergy were evaluated. In the study population, age and gender-adjusted prevalence of asthma and rhinitis symptoms in the last year was 14.6% and 34.1%, respectively (N = 739). By stool exam, ascariasis and trichuriasis were 62.5% and 35.7%, respectively. Significant odds ratio (OR) for asthma presentation were Ascaris sensitization, by specific-IgE (aOR: 2.69, 95%CI: 1.21-5.98) or skin prick test (OR: 3.59, 95%CI: 1.55-8.29). Moderate/severe ascariasis was protective from asthma (aOR: 0.34, 95%CI: 0.12-0.99) and moderate/severe trichuriasis from rhinitis (aOR: 0.35, 95%CI: 0.15-0.80). In conclusion, in a rural tropical village, ascariasis exerts risk and protective effects on asthma symptoms, an influence associated with the severity of the infection.

Parasites and allergy: Observations from Brazil

Brazil is a middle-income country undergoing the epidemiological transition. Effects of changes in daily life habits and access to clean water, sanitation and urban services on a growing urban population have contributed to a double burden of both infectious and noncommunicable chronic diseases. Studies have indicated that parasite infections may modulate the human immune system and influence the development of allergic conditions such as asthma. However, there is no consensus in the published literature on the effects of parasitic infections on allergy, perhaps as a consequence of factors determining the epidemiology of these infections that vary between populations such as age of first infection, duration and chronicity of infections, parasite burden and species, and host genetic susceptibility. In this review, we discuss the observations from Brazil concerning the relationship between parasite infections and allergy.

Parasite allergens

Human IgE against helminths is a normal component of the whole protective response elicitesd during infection, when specific IgE to a great number of antigens is produced; however, few of those IgE binding components are actually allergens. In general, considering the strong Th2/IgE responses during helminth infections is intriguing that they are not usually associated with allergic symptoms, which probably (but not exclusively) depends on parasite-induced immunomodulation. However, allergic manifestations have been described during some helminth infections such as ascariasis, strongyloidiasis, anisakiasis and hydatidosis. In addition, there is evidence that helminthiases (e.g. ascariasis) can increase symptoms in allergic patients. Furthermore, allergic reactions during anti-helminth vaccination have been observed, a problem that also could be associated to the future use of parasite derived immunomodulators. Therefore, identification and characterization of helminth allergens is a matter of increasing research and a great number of IgE binding antigens have been found (www.allergen.org and www.allergome.org). Here we describe only a small group of them, for which allergenic activity (the ability to induce IgE mediated inflammation) have been clinical or experimentally demonstrated. Ascaris lumbricoides tropomyosin (Asc l 3) has strong allergenic activity; in the Tropics it has been associated with asthma and asthma severity, suggesting clinical relevance. In addition, due to its cross reactivity with mite tropomyosins this allergen could influence house dust mite (HDM) allergy diagnosis. Characterized Ascaris allergens also include the polyprotein As s 1 (ABA-1) and the Glutathione transferase As l 13. Other helminth allergens include Anisakis simplex Ani s 1, Ani s 4, Ani s 7 and Ani s 9; Necator americanus NaASP2q and Nacal1 and Schistosoma mansoni SmVAL4 and Sm22.6. Future work on helminth IgE binding antigens will help to understand several aspects of allergenicity and allergenic activity, among them the increasing finding of IgE binding molecules that not induce allergic symptoms.

IgE sensitization to Anisakis pegreffii in Italy: Comparison of two methods for the diagnosis of allergic anisakiasis

IgE sensitization to Anisakis pegreffii in Italian subjects suffering from gastro-allergic anisakiasis (GAA) (N=5), or showing chronic urticaria (CU+) after fish consumption (N=100), was investigated. A control group (N=5) was also included. IgE response was analysed by immunoblotting (WB) assay, using both excretory/secretory products (ESPs) and crude extract (CE) of A. pegreffii larvae. The results were compared with those achieved by the conventional immunological method for Anisakis allergy (ie, immunoCAP). Among the 110 subjects, 28 showed IgE positivity with both WB and iCAP methods; 13 proved IgE reactivity, in WB assay, to ESP antigens of A. pegreffii, here provisionally indicated as Ani s 1-like, Ani s 7-like, Ani s 13-like; only 15 sera have shown IgE-WB reaction to Ani s 7-like and Ani s 13-like. iCAP and WB exhibited a high concordance value (κ=1.00) when iCAP value was <0.35 (negative result) and >50.0 (positive result). In the sera samples recorded as positive to Anisakis allergy, Ani s 1-like was responsible for 46.4% of the sensitivity, while Ani s 7-like and Ani s 13-like for 100%. They could be considered as major antigens in the diagnosis of allergic anisakiasis caused by A. pegreffii.

Genetic Variants in CHIA and CHI3L1 Are Associated with the IgE Response to the Ascaris Resistance Marker ABA-1 and the Birch Pollen Allergen Bet v 1

Helminth infections and allergic diseases are associated with IgE hyperresponsiveness but the genetics of this phenotype remain to be defined. Susceptibility to Ascaris lumbricoides infection and antibody levels to this helminth are associated with polymorphisms in locus 13q33-34. We aimed to explore this and other genomic regions to identify genetic variants associated with the IgE responsiveness in humans. Forty-eight subjects from Cartagena, Colombia, with extreme values of specific IgE to Ascaris and ABA-1, a resistance marker of this nematode, were selected for targeted resequencing. Burden analyses were done comparing extreme groups for IgE values. One-hundred one SNPs were genotyped in 1258 individuals of two well-characterized populations from Colombia and Sweden. Two low-frequency coding variants in the gene encoding the Acidic Mammalian Chitinase (CHIA rs79500525, rs139812869, tagged by rs10494133) were found enriched in high IgE responders to ABA-1 and confirmed by genetic association analyses. The SNP rs4950928 in the Chitinase 3 Like 1 gene (CHI3L1) was associated with high IgE to ABA-1 in Colombians and with high IgE to Bet v 1 in the Swedish population. CHIA rs10494133 and ABDH13 rs3783118 were associated with IgE responses to Ascaris. SNPs in the Tumor Necrosis Factor Superfamily Member 13b gene (TNFSF13B) encoding the cytokine B cell activating Factor were associated with high levels of total IgE in both populations. This is the first report on the association between low-frequency and common variants in the chitinases-related genes CHIA and CHI3L1 with the intensity of specific IgE to ABA-1 in a population naturally exposed to Ascaris and with Bet v 1 in a Swedish population. Our results add new information about the genetic influences of human IgE responsiveness; since the genes encode for enzymes involved in the immune response to parasitic infections, they could be helpful for understanding helminth immunity and allergic responses. We also confirmed that TNFSF13B has an important and conserved role in the regulation of total IgE levels, which supports potential evolutionary links between helminth immunity and allergic response.

Human Helminths and Allergic Disease: The Hygiene Hypothesis and Beyond

There is much debate about the interaction between helminths and allergic disease. The "Hygiene Hypothesis," a very popular concept among scientists and the lay public, states that infections, especially during childhood, can protect against allergic diseases. Indeed, helminth infections are known to induce regulatory responses in the host that can help the control of inflammation (including allergic inflammation). However, these infections also induce type-2-associated immune responses including helminth-specific IgE that can cross-react against environmental allergens and mediate IgE-driven effector responses. Thus, it is the delicate balance between the parasites' anti- and pro-allergenic effects that define the helminth/allergy interface.

Identification and Characterization of IgE-Binding Tropomyosins in Aedes aegypti

BACKGROUND

The mosquito Aedes aegypti is a potential source of important clinically relevant allergens. However, the allergenicity and cross-reactivity of most of these has not been fully described.

METHODS

Natural wild-type mosquito tropomyosin was purified by size exclusion and anionic-exchange chromatography from an A. aegypti extract. Further characterization was accomplished by MALDI-TOF/TOF. Two recombinant variants of tropomyosin were obtained by expression in Escherichia coli. Specific IgE measurement by ELISA and skin tests for mosquito extract were performed in 12 patients with asthma or allergy rhinitis residing on the Caribbean island of Martinique. Cross-reactivity between natural A. aegypti tropomyosin and recombinant tropomyosins from A. aegypti, house dust mite, shrimp and Ascaris lumbricoides was analyzed by ELISA competition.

RESULTS

Four variants of natural tropomyosin were purified. A band of 32 kDa in SDS-PAGE representing 2 tropomyosin variants (Aed a 10.0101 and Aed a 10.0201) reacted with specific IgE of 4 of the 12 (33%) allergic patients and with rabbit polyclonal anti-shrimp tropomyosin. A high degree of cross-reactivity (60-70%) was detected between natural mosquito tropomyosin and Blo t 10, Der p 10 and Lit v 1, and a lower degree with Asc l 3 from A. lumbricoides (<30%). rAed a 10.0101 inhibited IgE binding to natural A. aegypti tropomyosin; however, rAed a 10.0201 showed a low inhibitory capacity.

CONCLUSION

Tropomyosin is a new IgE-binding protein from A. aegypti. Two of the 4 variants identified showed different degree of cross-reactivity with tropomyosins from other arthropods. The potential allergenic role of each variant should be further investigated.

Particularities of allergy in the Tropics

Allergic diseases are distributed worldwide and their risk factors and triggers vary according to geographical and socioeconomic conditions. Allergies are frequent in the Tropics but aspects of their prevalence, natural history, risk factors, sensitizers and triggers are not well defined and some are expected to be different from those in temperate zone countries. The aim of this review is to investigate if allergic diseases in the Tropics have particularities that deserve special attention for research and clinical practice. Such information will help to form a better understanding of the pathogenesis, diagnosis and management of allergic diseases in the Tropics. As expected, we found particularities in the Tropics that merit further study because they strongly affect the natural history of common allergic diseases; most of them related to climate conditions that favor permanent exposure to mite allergens, helminth infections and stinging insects. In addition, we detected several unmet needs in important areas which should be investigated and solved by collaborative efforts led by the emergent research groups on allergy from tropical countries.

EAACI Molecular Allergology User's Guide

The availability of allergen molecules ('components') from several protein families has advanced our understanding of immunoglobulin E (IgE)-mediated responses and enabled 'component-resolved diagnosis' (CRD). The European Academy of Allergy and Clinical Immunology (EAACI) Molecular Allergology User's Guide (MAUG) provides comprehensive information on important allergens and describes the diagnostic options using CRD. Part A of the EAACI MAUG introduces allergen molecules, families, composition of extracts, databases, and diagnostic IgE, skin, and basophil tests. Singleplex and multiplex IgE assays with components improve both sensitivity for low-abundance allergens and analytical specificity; IgE to individual allergens can yield information on clinical risks and distinguish cross-reactivity from true primary sensitization. Part B discusses the clinical and molecular aspects of IgE-mediated allergies to foods (including nuts, seeds, legumes, fruits, vegetables, cereal grains, milk, egg, meat, fish, and shellfish), inhalants (pollen, mold spores, mites, and animal dander), and Hymenoptera venom. Diagnostic algorithms and short case histories provide useful information for the clinical workup of allergic individuals targeted for CRD. Part C covers protein families containing ubiquitous, highly cross-reactive panallergens from plant (lipid transfer proteins, polcalcins, PR-10, profilins) and animal sources (lipocalins, parvalbumins, serum albumins, tropomyosins) and explains their diagnostic and clinical utility. Part D lists 100 important allergen molecules. In conclusion, IgE-mediated reactions and allergic diseases, including allergic rhinoconjunctivitis, asthma, food reactions, and insect sting reactions, are discussed from a novel molecular perspective. The EAACI MAUG documents the rapid progression of molecular allergology from basic research to its integration into clinical practice, a quantum leap in the management of allergic patients.

IgE responses to Ascaris and mite tropomyosins are risk factors for asthma

BACKGROUND

The relationship between helminthiases and allergy is a matter of considerable interest and research. In the tropics, house dust mite exposure, a known risk factor for asthma, is frequently concurrent with helminth infections. It remains to be defined whether infection with the common roundworm Ascaris or its bystander immunological effects influence the prevalence and pathogenesis of asthma independently of mite sensitization.

OBJECTIVE

To investigate the relationship between the IgE responses to Ascaris and its purified allergens and the risk of asthma in a tropical country.

METHODS

A nested case-control study was performed in 356 subjects who reported current and past asthma symptoms (asthmatics) and 435 controls that had never experienced such symptoms. They were tested for serum levels of total IgE and specific IgE to Ascaris extract, Asc s 1 (ABA-1), Asc l 3 (tropomyosin) and GST (glutathione transferase). In addition, specific IgE to Dermatophagoides pteronyssinus, Blomia tropicalis and their tropomyosins Der p 10 and Blo t 10 was measured. Sensitization was defined as a positive specific IgE result to any extract or recombinant allergen.

RESULTS

Sensitization to Ascaris and D. pteronyssinus was independently associated with asthma after adjustment for age, gender, socio-economic stratum, city and other IgE levels (adjusted ORs: 2.17; 95% CI 1.37-3.42 and 2.46; 95% CI 1.54-3.92), respectively. There was also a significant association with sensitization to the highly allergenic and cross-reactive tropomyosins Asc l 3, Blo t 10 and Der p10 (aORs: 1.76; 95% CI 1.21-2.57, 1.64; 95% CI 1.14-2.35 and 1.51; 95% CI 1.02-2.24), respectively.

CONCLUSION AND CLINICAL RELEVANCE

IgE responses to Ascaris are associated with asthma symptoms in a population living in the tropics. Sensitization to the cross-reactive Ascaris and mite tropomyosins partially underlies this finding. These results have potential relevance in asthma diagnosis and management.

Meteorological conditions, climate change, new emerging factors, and asthma and related allergic disorders. A statement of the World Allergy Organization

The prevalence of allergic airway diseases such as asthma and rhinitis has increased dramatically to epidemic proportions worldwide. Besides air pollution from industry derived emissions and motor vehicles, the rising trend can only be explained by gross changes in the environments where we live. The world economy has been transformed over the last 25 years with developing countries being at the core of these changes. Around the planet, in both developed and developing countries, environments are undergoing profound changes. Many of these changes are considered to have negative effects on respiratory health and to enhance the frequency and severity of respiratory diseases such as asthma in the general population.

Increased concentrations of greenhouse gases, and especially carbon dioxide (CO₂), in the atmosphere have already warmed the planet substantially, causing more severe and prolonged heat waves, variability in temperature, increased air pollution, forest fires, droughts, and floods – all of which can put the respiratory health of the public at risk. These changes in climate and air quality have a measurable impact not only on the morbidity but also the mortality of patients with asthma and other respiratory diseases. The massive increase in emissions of air pollutants due to economic and industrial growth in the last century has made air quality an environmental problem of the first order in a large number of regions of the world. A body of evidence suggests that major changes to our world are occurring and involve the atmosphere and its associated climate. These changes, including global warming induced by human activity, have an impact on the biosphere, biodiversity, and the human environment. Mitigating this huge health impact and reversing the effects of these changes are major challenges.

This statement of the World Allergy Organization (WAO) raises the importance of this health hazard and highlights the facts on climate-related health impacts, including: deaths and acute morbidity due to heat waves and extreme meteorological events; increased frequency of acute cardio-respiratory events due to higher concentrations of ground level ozone; changes in the frequency of respiratory diseases due to trans-boundary particle pollution; altered spatial and temporal distribution of allergens (pollens, molds, and mites); and some infectious disease vectors. According to this report, these impacts will not only affect those with current asthma but also increase the incidence and prevalence of allergic respiratory conditions and of asthma. The effects of climate change on respiratory allergy are still not well defined, and more studies addressing this topic are needed. Global warming is expected to affect the start, duration, and intensity of the pollen season on the one hand, and the rate of asthma exacerbations due to air pollution, respiratory infections, and/or cold air inhalation, and other conditions on the other hand.

The IgE response to Ascaris molecular components is associated with clinical indicators of asthma severity

Background

Asthma is a common chronic disease worldwide and Ascaris lumbricoides infection (ascariasis) is frequent in tropical regions. However, the effect of ascariasis on asthma severity has not been sufficiently explored. We sought to evaluate the influence of the IgE immune response to Ascaris extract and purified house dust mites (HDM) and Ascaris allergens on indicators of asthma severity in patients living in the tropics.

Methods

Asthmatic patients from Cartagena, Colombia were recruited. Clinical assessment included questionnaires, physical examination, allergy skin tests, spirometry, parasite stool examination and IgE antibody measurements. Asthma was diagnosed by a physician according to validated criteria. Indicators of severity were occurrence of severe dyspnea episodes, night awakenings events, > 4 emergency room (ER) visits and hospitalizations during the last year. Specific IgE to Der p 2, Ascaris spp., Blomia tropicalis and Dermatophagoides pteronyssinus extracts was determined by ImmunoCap. IgE to tropomyosins (Asc l 3, Blo t 10 and Der p 10), Blo t 5 and Asc s 1 was detected by ELISA. Logistic regression analyses were used to explore the relationships between sensitization and indicators of asthma severity.

Results

After adjustment for HDM sensitization, Ascaris sensitization remained associated with severe dyspnea (aOR: 1.90, 95% CI: 1.08 - 3.34, p = 0.03) and > 4 ER visits (aOR: 2.23, 95% CI: 1.15 - 4.30, p = 0.02). We also found that sensitization to the species specific markers Blo t 5 and Asc s 1, as well as the cross-reactive tropomyosins of D. pteronyssinus and Ascaris were associated with > 4 ER visits. Der p 2 sensitization was associated with bronchodilator responsiveness (aOR: 2.24: 1.25-4.02, p = 0.01). Remarkably, significantly higher IgE levels to HDM species specific allergens were found in Ascaris sensitized patients.

Conclusions

In this tropical population, IgE sensitization to Ascaris and the cross-reactive tropomyosins was frequent and associated with clinical indicators of asthma severity. The significant relationship between sensitization to the nematode-specific marker Asc s 1 and ER attendance supports these findings. Moreover, ascariasis increases the human IgE responses to HDM specific allergens.

Natural antibody repertoires: development and functional role in inhibiting allergic airway disease

In this review we discuss the effects of microbial exposure on the B cell repertoire. Neonatal exposure to conserved bacterial carbohydrates and phospholipids permanently reprograms the natural antibody repertoire directed toward these antigens by clonal expansion, alterations in clonal dominance, and increased serum antibody levels. These epitopes are present not only in bacterial cell walls, but also in common environmental allergens. Neonatal immunization with bacterial polysaccharide vaccines results in attenuated allergic airway responses to fungi-, house dust mite-, and cockroach-associated allergens in mouse models. The similarities between mouse and human natural antibody repertoires suggest that reduced microbial exposure in children may have the opposite effect, providing a potential mechanistic explanation for the hygiene hypothesis. We propose that understanding the effects of childhood infections on the natural antibody repertoire and the mechanisms of antibody-mediated immunoregulation observed in allergy models will lead to the development of prevention/interventional strategies for treatment of allergic asthma.

The strength of the antibody response to the nematode Ascaris lumbricoides inversely correlates with levels of B-Cell Activating Factor (BAFF)

Background

B-Cell Activating Factor (BAFF) is a cytokine regulating antibody production. Polymorphisms in the gene encoding BAFF were associated with the antibody response to Ascaris but not to mite allergens. In the present study we evaluated the relationship between BAFF and specific antibodies against Ascaris and mites in 448 controls and 448 asthmatics. Soluble BAFF was measured by ELISA and BAFF mRNA by qPCR. Surface expression of BAFF and its receptor (BAFF-R) was analyzed by flow cytometry.

Results

Individuals with specific IgE levels to Ascaris >75th percentile had lower levels of soluble BAFF; those with specific IgG levels to Ascaris >75th percentile had reduced BAFF mRNA. Total IgE and specific IgE to mites were not related to BAFF levels. There were no differences in soluble BAFF or mRNA levels between asthmatics and controls. There was an inverse relationship between the cell-surface expression of BAFF-R on CD19⁺ B cells and BAFF levels at the transcriptional and protein level.

Conclusions

These findings suggest that differences in BAFF levels are related to the strength of the antibody response to Ascaris.

Effective anthelmintic therapy of residents living in endemic area of high prevalence for Hookworm and Schistosoma mansoni infections enhances the levels of allergy risk factor anti-Der p1 IgE

In this work were investigated the relationship between Hookworm/Schistosoma mansoni infections and allergy related risk factors in two endemic areas with distinct prevalence of infections and co-infection. The intensity of infections, eosinophilia, allergy risk factors, infections status and anti-Der p1 IgE levels before and 2 years (population 1) and 3 years (population 2) after anthelmintic treatment, were evaluated. It was observed that the population with lower prevalence and intensity of infection (population 2) had lower eosinophils counts (>600/mm³) and higher animal contact than the population with higher parasites intensity (population 1). After anthelmintic treatment the intensity of S. mansoni single infection decreased, but no changes were observed in Hookworm and co-infected individuals. The anthelmintic treatment also enhanced anti-Der p1 IgE optical density in ELISA on the subgroups that became negative for helminth infection regardless of their previous infection condition in population 1. Facing that, we evaluated the anti-Der p1 IgE reactivity index, and the ratio (after/before treatment) was significantly higher in patients co-infected before treatment. On the other hand, no association between anti-Der p1 IgE reactivity index and the intensity of infections were observed. In conclusion, effective anthelmintic therapy of subjects from endemic areas with high prevalence of Hookworm and S. mansoni infections enhances anti-Der p1 IgE levels.

Early life IgE responses in children living in the tropics: a prospective analysis

BACKGROUND

There are few birth cohort studies analyzing IgE sensitization in the tropics.

OBJECTIVES

We aimed to describe the evolution of total IgE and specific IgE responses to house-dust mite (HDM) allergens and Ascaris in a birth cohort (Risk Factors for Asthma and Allergy in the Tropics, FRAAT), analyzing their relationships with wheezing.

METHODS

Total and specific IgE were measured by ImmunoCap in mothers and children at four different time points (S1-S4) between 0 and 42 months. Parasite infection was evaluated by stool examination.

RESULTS

Maternal total IgE (aOR: 2.43, 95% CI: 1.09-5.43; p = 0.03) and socio-demographic factors were associated with high cord blood (CB) total IgE. High CB total IgE was positively associated with higher Blomia tropicalis and Ascaris-specific IgE values during lifetime, but protected from recurrent wheezing (aOR: 0.26, 95% CI: 0.08-0.88, p = 0.03). Prevalence rates of IgE sensitization were high; at around 3 yr old, they were 33.3, 18.6, and 26.5% for B. tropicalis, Dermatophagoides pteronyssinus, and Ascaris, respectively. Indicators of unhygienic conditions were risk factors for HDM and Ascaris sensitization in children. A weak statistical association between B. tropicalis-specific IgE and ever wheezing was found (aOR: 1.47 95% CI: 1.00-2.28, p = 0.05).

CONCLUSIONS

In a socioeconomically deprived community from the tropics, sensitization to HDM allergens was very frequent at early life, especially to B. tropicalis. In contrast to expected according to the hygiene hypothesis, unhygienic/poverty conditions were risk factors for allergen sensitization. High CB total IgE levels were a risk factor for allergen sensitization but protected from recurrent wheezing.

Proteomic and immunochemical characterization of glutathione transferase as a new allergen of the nematode Ascaris lumbricoides

Helminth infections and allergy have evolutionary and clinical links. Infection with the nematode Ascaris lumbricoides induces IgE against several molecules including invertebrate pan-allergens. These antibodies influence the pathogenesis and diagnosis of allergy; therefore, studying parasitic and non-parasitic allergens is essential to understand both helminth immunity and allergy. Glutathione transferases (GSTs) from cockroach and house dust mites are clinically relevant allergens and comparative studies between them and the GST from A. lumbricoides (GSTA) are necessary to evaluate their allergenicity. We sought to analyze the allergenic potential of GSTA in connection with the IgE response to non-parasitic GSTs. IgE to purified GSTs from Ascaris (nGSTA and rGSTA), house dust mites (rDer p 8, nBlo t 8 and rBlo t 8), and cockroach (rBla g 5) was measured by ELISA in subjects from Cartagena, Colombia. Also, multidimensional proteomic approaches were used to study the extract of A. lumbricoides and investigate the existence of GST isoforms. We found that among asthmatics, the strength of IgE levels to GSTA was significantly higher than to mite and cockroach GSTs, and there was a strong positive correlation between IgE levels to these molecules.

Specific IgE to GSTA was found in 13.2% of controls and 19.5% of asthmatics. In addition nGSTA induced wheal and flare in skin of sensitized asthmatics indicating that it might be of clinical relevance for some patients. Frequency and IgE levels to GSTA were higher in childhood and declined with age. At least six GST isoforms in A. lumbricoides bind human IgE. Four isoforms were the most abundant and several amino acid substitutions were found, mainly on the N-terminal domain. In conclusion, a new allergenic component of Ascaris has been discovered; it could have clinical impact in allergic patients and influence the diagnosis of mite and cockroach allergy in tropical environments.

Investigating cockroach allergens: aiming to improve diagnosis and treatment of cockroach allergic patients

Cockroach allergy is an important health problem associated with the development of asthma, as a consequence of chronic exposure to low levels of allergens in susceptible individuals. In the last 20 years, progress in understanding the disease has been possible, thanks to the identification and molecular cloning of cockroach allergens and their expression as recombinant proteins. Assays for assessment of environmental allergen exposure have been developed and used to measure Bla g 1 and Bla g 2, as markers of cockroach exposure. IgE antibodies to cockroach extracts and to specific purified allergens have been measured to assess sensitization and analyze association with exposure and disease. With the development of the field of structural biology and the expression of recombinant cockroach allergens, insights into allergen structure, function, epitope mapping and allergen-antibody interactions have provided further understanding of mechanisms of cockroach allergic disease at the molecular level. This information will contribute to develop new approaches to allergen avoidance and to improve diagnosis and therapy of cockroach allergy.

New occupational and environmental causes of asthma and extrinsic allergic alveolitis

Asthma and extrinsic allergic alveolitis (EAA) remain prevalent respiratory diseases and the cause of a significant disease burden. This article reviews the recent occupational and environmental causes described for these conditions. Even over the limited time spam addressed by this article, novel agents and new data relating to already suggested causes have been described. Various types of work tasks or exposures are described that appear to cause both asthma and EAA. Isocyanates, the best example of dual potential to cause asthma and EAA are discussed, as is the new understanding of the role metal-working fluids play when causing respiratory diseases.

Efficacy of recombinant allergens for diagnosis of cockroach allergy in patients with asthma and/or rhinitis

BACKGROUND

Immunoglobulin E (IgE) reactivity to individual allergens among cockroach-allergic patients has revealed wide variability. The aim of this study was to assess the effectiveness of recombinant cockroach allergens for skin testing, and to determine sensitization profiles among cockroach-allergic patients living in Brazil.

METHODS

Fifty-seven cockroach-allergic patients with asthma and/or rhinitis were recruited. Skin testing with recombinant (r) allergens from Periplaneta americana (rPer a 1 and rPer a 7) and Blattella germanica (rBla g 2, rBla g 4 and rBla g 5) were performed at 10 μg/ml and 5 μg/ml (rPer a 1). IgE antibodies to rPer a 7 and rPer a 1 were quantitated by ELISA.

RESULTS

Of 57 patients tested, 3 (5.3%), 24 (42.1%), 4 (7%), 3 (5.3%) and 4 (7%) showed positive reactions to rPer a 1, rPer a 7, rBla g 2, rBla g 4 and rBla g 5, respectively. Twenty-eight patients (49.1%) had positive tests to at least one allergen. In keeping with skin test results, 31/57 patients (54.4%) and 5/55 patients (9%) had detectable IgE to rPer a 7 and rPer a 1, respectively. Levels of IgE to rPer a 7 were higher in patients with positive tests to rPer a 7 than those with negative tests (geometric mean 13.2 and 1.8 IU/ml, p < 0.05). There was good concordance of results of skin tests and measurements of serum IgE to rPer a 7.

CONCLUSION

IgE reactivity to rPer a 7 (P. americana tropomyosin) was dominant among patients in Brazil. However, 50% of the patients did not present reactivity to any of the recombinant allergens tested.

New Allergens of Relevance in Tropical Regions: The Impact of Ascaris lumbricoides Infections

One of the many aspects of the relationships between parasite infections and allergic diseases is the possibility that allergens from parasites enhance the T_H2 responses, especially IgE production, in allergic diseases such as asthma. In this review we discuss about the allergenic composition of the nematode Ascaris lumbricoides and their potential impact on allergy sensitization and asthma pathogenesis and prevalence in populations living in the tropics and naturally exposed to both, mite allergens and helminth infections.

Prevalence of asthma and other allergic conditions in Colombia 2009-2010: a cross-sectional study

Background

While it is suggested that the prevalence of asthma in developed countries may have stabilized, this is not clear in currently developing countries. Current available information for both adults and children simultaneously on the burden and impact of allergic conditions in Colombia and in many Latin American countries is limited. The objectives of this study were to estimate the prevalence for asthma, allergic rhinitis (AR), atopic eczema (AE), and atopy in six colombian cities; to quantify costs to the patient and her/his family; and to determine levels of Immunoglobulin E (IgE) in asthmatic and healthy subjects.

Methods

We conducted a cross-sectional, population-based study in six cities during the academic year 2009–2010. We used a school-based design for subjects between 5–17 years old. We carried out a community-based strategy for subjects between 1–4 years old and adults between 18–59 years old. Serum samples for total and antigen-specific (IgE) levels were collected using a population-based, nested, case–control design.

Results

We obtained information on 5978 subjects. The largest sample of subjects was collected in Bogotá (2392). The current prevalence of asthma symptoms was 12% (95% CI, 10.5-13.7), with 43% (95% CI, 36.3-49.2) reporting having required an emergency department visit or hospitalization in the past 12 months. Physician diagnosed asthma was 7% (95% CI, 6.1-8.0). The current prevalence of AR symptoms was 32% (95% CI, 29.5-33.9), and of AE symptoms was 14% (95% CI, 12.5-15.3). We collected blood samples from 855 subjects; 60.2% of asthmatics and 40.6% of controls could be classified as atopic.

Conclusions

In Colombia, symptom prevalence for asthma, AR and AE, as well as levels of atopy, are substantial. Specifically for asthma, symptom severity and absence from work or study due to symptoms are important. These primary care sensitive conditions remain an unmet public health burden in developing countries such as Colombia.

Modulation of specific and allergy-related immune responses by helminths

Helminths are master regulators of host immune responses utilising complex mechanisms to dampen host protective Th2-type responses and favour long-term persistence. Such evasion mechanisms ensure mutual survival of both the parasite and the host. In this paper, we present recent findings on the cells that are targeted by helminths and the molecules and mechanisms that are induced during infection. We discuss the impact of these factors on the host response as well as their effect in preventing the development of aberrant allergic inflammation. We also examine recent findings on helminth-derived molecules that can be used as tools to pinpoint the underlying mechanisms of immune regulation or to determine new anti-inflammatory therapeutics.

IgE cross-reactivity between Ascaris lumbricoides and mite allergens: possible influences on allergic sensitization and asthma

Nematode infections such as Ascariasis are important health problems in underdeveloped countries, most of them located in the tropics where environmental conditions also promote the perennial co-exposure to high concentrations of domestic mite allergens. Allergic diseases are common, and most of patients with asthma exhibit a predominant and strong IgE sensitization to mites. It is unknown whether co-exposure to Ascaris lumbricoides and the domestic mites Blomia tropicalis and Dermatophagoides pteronyssinus potentiates Th2 responses and IgE sensitization, thereby modifying the natural history of allergy. Recently, we obtained experimental evidence of a high cross-reactivity between the allergenic extracts of these invertebrates, involving well-known allergens such as tropomyosin and glutathione transferases. There is indirect evidence suggesting that the clinical impact of these findings may be important. In this review, we discuss the potential role of this cross-reactivity on several aspects of allergy in the tropics that have been a focus of a number of investigations, some of them with controversial results.