Self-reported hypersensitivity and allergy to foods amongst Mexican adolescents: Prevalence and associated factors

Background: The prevalence of food allergy is on the rise on a global scale. Objective: To determine the prevalence of food hypersensitivity (FHS) and probable food allergy (PFA), as well as the foods and factors associated with these occurrences. Methods: A cross-sectional study was carried out among 1992 adolescents (aged 15-18 years). Each adolescent answered a structured questionnaire. A multivariate analysis was used to identify the association between the variables. Results: The prevalence of FHS was 10.6% (the most commonly associated foods were shrimp, cow's milk and avocado) and the PFA was 7.8% (shrimp, cow's milk and pecan). The prevalences of oral allergy syndrome, food-associated urticaria and systemic reaction were 4.9%, 3.6% and 1.5%, respectively. The following factors were associated with FHS: personal history of asthma (OR 1.63; 95% CI: 1.11-2.41), allergic rhinitis (OR 2.60; 95% CI: 1.75-3.87), atopic dermatitis (OR 2.07; 95% CI: 1.25-3.43), maternal history of asthma (OR 1.80; 95% CI: 1.02-3.16), atopic dermatitis (OR 6.11; 95% CI: 2.45-15.29), and female sex (OR 1.89; 95% CI: 1.38-2.59). PFA was associated with a personal history of asthma (OR 1.65; 95% CI: 1.06-2.56), allergic rhinitis (OR 2.46; 95% CI: 1.56-3.88), atopic dermatitis (OR 2.02; 95% CI: 1.15-3.54), paternal allergic rhinitis (OR 2.52; 95% CI: 1.15-5.51), maternal atopic dermatitis (OR 7.46; 95% CI: 2.93-19.00), and female sex (OR 1.89; 95% CI: 1.31-2.72). Conclusion: The adverse reactions associated with foods among late adolescents are a frequent occurrence, and the most commonly associated factor is atopy

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Self-reported hypersensitivity and allergy to foods amongst Mexican adolescents: Prevalence and associated factors.

BACKGROUND: The prevalence of food allergy is on the rise on a global scale. OBJECTIVE: To determine the prevalence of food hypersensitivity (FHS) and probable food allergy (PFA), as well as the foods and factors associated with these occurrences. METHODS: A cross-sectional study was carried out among 1992 adolescents (aged 15-18 years). Each adolescent answered a structured questionnaire. A multivariate analysis was used to identify the association between the variables. RESULTS: The prevalence of FHS was 10.6% (the most commonly associated foods were shrimp, cow's milk and avocado) and the PFA was 7.8% (shrimp, cow's milk and pecan). The prevalences of oral allergy syndrome, food-associated urticaria and systemic reaction were 4.9%, 3.6% and 1.5%, respectively. The following factors were associated with FHS: personal history of asthma (OR 1.63; 95% CI: 1.11-2.41), allergic rhinitis (OR 2.60; 95% CI: 1.75-3.87), atopic dermatitis (OR 2.07; 95% CI: 1.25-3.43), maternal history of asthma (OR 1.80; 95% CI: 1.02-3.16), atopic dermatitis (OR 6.11; 95% CI: 2.45-15.29), and female sex (OR 1.89; 95% CI: 1.38-2.59). PFA was associated with a personal history of asthma (OR 1.65; 95% CI: 1.06-2.56), allergic rhinitis (OR 2.46; 95% CI: 1.56-3.88), atopic dermatitis (OR 2.02; 95% CI: 1.15-3.54), paternal allergic rhinitis (OR 2.52; 95% CI: 1.15-5.51), maternal atopic dermatitis (OR 7.46; 95% CI: 2.93-19.00), and female sex (OR 1.89; 95% CI: 1.31-2.72). CONCLUSION: The adverse reactions associated with foods among late adolescents are a frequent occurrence, and the most commonly associated factor is atopy.

Transcriptome analysis of an incompatible Persea americana-Phytophthora cinnamomi interaction reveals the involvement of SA- and JA-pathways in a successful defense response.

Phytophthora cinnamomi Rands (Pc) is a hemibiotrophic oomycete and the causal agent of Phytophthora root rot (PRR) of the commercially important fruit crop avocado (Persea americana Mill.). Plant defense against pathogens is modulated by phytohormone signaling pathways such as salicylic acid (SA), jasmonic acid (JA), ethylene (ET), auxin and abscisic acid. The role of specific signaling pathways induced and regulated during hemibiotroph-plant interactions has been widely debated. Some studies report SA mediated defense while others hypothesize that JA responses restrict the spread of pathogens. This study aimed to identify the role of SA- and JA- associated genes in the defense strategy of a resistant avocado rootstock, Dusa in response to Pc infection. Transcripts associated with SA-mediated defense pathways and lignin biosynthesis were upregulated at 6 hours post-inoculation (hpi). Results suggest that auxin, reactive oxygen species (ROS) and Ca2+ signaling was also important during this early time point, while JA signaling was absent. Both SA and JA defense responses were shown to play a role during defense at 18 hpi. Induction of genes associated with ROS detoxification and cell wall digestion (ß-1-3-glucanase) was also observed. Most genes induced at 24 hpi were linked to JA responses. Other processes at play in avocado at 24 hpi include cell wall strengthening, the formation of phenolics and induction of arabinogalactan, a gene linked to Pc zoospore immobility. This study represents the first transcriptome wide analysis of a resistant avocado rootstock treated with SA and JA compared to Pc infection. The results provide evidence of a biphasic defense response against the hemibiotroph, which initially involves SA-mediated gene expression followed by the enrichment of JA-mediated defense from 18 to 24 hpi. Genes and molecular pathways linked to Pc resistance are highlighted and may serve as future targets for manipulation in the development of PRR resistant avocado rootstocks.

EST sequencing and gene expression profiling of defence-related genes from Persea americana infected with Phytophthora cinnamomi.

BACKGROUND: Avocado (Persea americana) belongs to the Lauraceae family and is an important commercial fruit crop in over 50 countries. The most serious pathogen affecting avocado production is Phytophthora cinnamomi which causes Phytophthora root rot (PRR). Root pathogens such as P. cinnamomi and their interactions with hosts are poorly understood and despite the importance of both the avocado crop and the effect Phytophthora has on its cultivation, there is a lack of molecular knowledge underpinning our understanding of defence strategies against the pathogen. In order to initiate a better understanding of host-specific defence we have generated EST data using 454 pyrosequencing and profiled nine defence-related genes from Pc-infected avocado roots. RESULTS: 2.0 Mb of data was generated consisting of ~10,000 reads on a single lane of the GS FLX platform. Using the Newbler assembler 371 contigs were assembled, of which 367 are novel for Persea americana. Genes were classified according to Gene Ontology terms. In addition to identifying root-specific ESTs we were also able to identify and quantify the expression of nine defence-related genes that were differentially regulated in response to P. cinnamomi. Genes such as metallothionein, thaumatin and the pathogenesis related PsemI, mlo and profilin were found to be differentially regulated. CONCLUSIONS: This is the first study in elucidating the avocado root transcriptome as well as identifying defence responses of avocado roots to the root pathogen P. cinnamomi. Our data is currently the only EST data that has been generated for avocado rootstocks, and the ESTs identified in this study have already been useful in identifying defence-related genes as well as providing gene information for other studies looking at processes such as ROS regulation as well as hypoxia in avocado roots. Our EST data will aid in the elucidation of the avocado transcriptome and identification of markers for improved rootstock breeding and screening. The characterization of the avocado transcriptome will furthermore form a basis for functional genomics of basal angiosperms.

AV119, a natural sugar from avocado gratissima, modulates the LPS-induced proinflammatory response in human keratinocytes.

Keratinocytes play an active role in innate immune responses by secreting a variety of cytokines and chemokines. The release of critical proinflammatory cytokines, which are necessary to activate the immune response, is induced by the stimulation of Toll-like receptors (TLRs) by molecules present on pathogenic micro-organisms such as lipopolysaccharide (LPS). AV119, a patented blend of avocado sugars, induced the aggregation of Malassezia furfur, a dimorphic, lipid-dependent yeast that is part of the normal human cutaneous commensal flora and inhibited its penetration into the keratinocytes. In the present study, the anti-inflammatory effects of AV119 were investigated in LPS-induced inflammation of human keratinocytes. In particular, we analysed the modulation of the LPS-induced expression of proinflammatory cytokines and heat shock protein 70 (HSP70) by AV119 and the involvement of TLR-4. Our data show that AV119 is able to modulate significantly the proinflammatory response in human keratinocytes, blocking the NF-kB activation in human keratinocytes.

Differential allergen sensitization patterns in chestnut allergy with or without associated latex-fruit syndrome.

BACKGROUND: Chestnut allergy has been almost exclusively considered in the context of the latex-fruit syndrome. Chestnut allergens not linked to latex hypersensitivity have not been studied. OBJECTIVE: We sought to explore whether differences in sensitization patterns between chestnut allergy with or without associated latex-fruit syndrome can be detected. METHODS: Twelve patients sensitized to chestnut but not to latex and 3 control patients with latex-chestnut allergy were analyzed. A major chestnut allergen was purified and characterized. IgE immunoblotting, specific IgE determination, and skin prick tests with 5 isolated allergens involved in food allergy or latex-fruit syndrome were also performed. RESULTS: A major 9-kd allergen was detected in chestnut extract, isolated, and identified as lipid transfer protein (LTP) Cas s 8. Specific IgE to this allergen was found in 91% (by means of IgE immunoblotting) and 58% (by means of ELISA) of sera from patients with chestnut but not latex allergy. Moreover, 66% of these patients had positive skin prick test responses to Cas s 8. Additionally, allergenic LTPs from peach fruit and Artemisia vulgaris pollen were also reactive. In contrast, avocado class I chitinase and latex hevein, allergens associated with the latex-fruit syndrome, showed no reaction. The opposite situation was exhibited by patients with latex-chestnut allergy. CONCLUSIONS: Patients with chestnut allergy with or without associated latex hypersensitivity present different patterns of major allergens (LTPs and class I chitinases, respectively). CLINICAL IMPLICATIONS: LTPs and class I chitinases can be used as diagnostic tools in patients with chestnut allergy to predict whether an associated latex sensitization and a risk of potential cross-reactivity with other plant foods and pollens exist.

Isolated hevein-like domains, but not 31-kd endochitinases, are responsible for IgE-mediated in vitro and in vivo reactions in latex-fruit syndrome.

BACKGROUND: Individuals with natural rubber latex allergy often have immediate reactions to plant-derived foods and fresh fruits, such as avocado and banana. IgE of these patients has been shown to bind endochitinases containing an N-terminal hevein-like domain (HLD). However, evidence on 31-kd endochitinase-induced reactions in vivo is lacking. OBJECTIVE: We sought to assess the clinical significance of 31-kd endochitinases and isolated HLDs in latex-fruit syndrome. METHODS: The 31-kd endochitinases and corresponding HLDs were purified or produced from avocado, banana, latex, and wheat germ. Skin prick test reactivities against purified proteins were examined in 15 patients with natural rubber latex allergy. The binding efficiency of IgE to purified proteins was studied by using an inhibition ELISA. Experimentally resolved or modeled structures of the proteins were compared to clarify the molecular basis of clinical reactions. RESULTS: Eleven (73%) patients had skin prick test reactions to isolated HLDs of avocado and banana, but only 1 (7%) patient reacted to their corresponding 31-kd endochitinases. HLDs from avocado and banana inhibited binding of IgE to prohevein (Hev b 6.01) in 59% and 38% of patients, respectively, whereas corresponding percentages for 31-kd endochitinases were 17% and 20%, respectively. Isolated HLDs of wheat germ agglutinin and 18-kd wheat germ agglutinin did not significantly inhibit IgE binding to hevein. CONCLUSION: The isolated HLD molecules alone, but not when linked to endochitinases, seem to be responsible for IgE-mediated clinical reactions in latex-fruit syndrome. Careful selection of relevant allergens in their proper molecular form is therefore crucial in forming a reliable diagnosis of latex-fruit syndrome.

Analysis of avocado allergen (Prs a 1) IgE-binding peptides generated by simulated gastric fluid digestion.

BACKGROUND: Resistance to pepsin digestion has been claimed to be a characteristic of food allergens that can induce severe adverse reactions. Moreover, pepsin treatment is included in protocols to evaluate the potential allergenicity of transgenic foods. Allergenic plant class I chitinases, such as avocado Prs a 1, are the panallergens involved in the latex-fruit syndrome. Previous reports indicated their susceptibility to simulated gastric fluid (SGF) digestion. OBJECTIVE: We sought to evaluate the IgE-binding capacity and the in vivo reactivity of the SGF products of the avocado allergen Prs a 1. METHODS: Patients with a clinical history of latex-fruit allergy syndrome, a positive skin prick test (SPT) response to Prs a 1, and specific IgE to avocado were selected. Untreated and SGF-digested Prs a 1 samples were analyzed by means of IgE and IgG immunoblotting, IgE immunoblotting and ELISA-inhibition assays, and SPTs. Peptides from SGF-digested samples were fractionated by means of HPLC, characterized by N-terminal amino acid sequencing and matrix-assisted laser desorption/ionization analysis, and tested for in vivo reactivity with SPTs. RESULTS: Neither protein staining nor IgE immunoblotting with a pool of sera from allergic patients resulted in the detection of any band after SDS-PAGE separation of an SGF-digested sample of Prs a 1. However, this sample showed a similar inhibitory potency to that of untreated Prs a 1 in both immunoblot- and ELISA-inhibition assays (up to 70% inhibition of the IgE binding to crude avocado extract) and induced positive SPT responses in 5 of 8 allergic patients. Peptides from SGF-digested Prs a 1 were separated by means of HPLC, and 4 of them reached more than 50% inhibition values when using avocado extract as the solid phase in ELISA-inhibition assays. Reactive peptides were located both in the N-terminal hevein-like domain and in the catalytic domain of Prs a 1. Those corresponding to the hevein-like domain (approximately 5100 d) produced positive SPT responses in 5 of 8 allergic patients, whereas 2 peptides located in the catalytic domain (approximately 1400 and 2500 d) were reactive in 2 or 3 of the 8 patients. CONCLUSION: Prs a 1 was extensively degradated when subjected to SGF digestion. However, the resulting peptides, particularly those corresponding to the hevein-like domain, were clearly reactive both in vitro and in vivo.