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Background Given the increased popularity of flaxseed in meals, several cases of allergy to these seeds have been reported. Little is known about allergens implicated in hypersensitivity reactions to these seeds. The present work aimed to identify the allergens involved in IgE-mediated reactions in five patients with a clinical history of severe systemic symptoms after flaxseed consumption. Methods Proteins susceptible to be allergens with IgE-binding capacity were purified from flaxseed extract by chromatographic techniques. Their identification was achieved via MALDI-TOF mass spectrometry. Immunoassays were performed using the five allergic patient's era either by testing them individually or as a pool. Results Proteins susceptible to be allergens with IgE-binding capacity were purified from flaxseed extract by chromatographic techniques. Their identification was achieved via MALDI-TOF mass spectrometry. Immunoassays were performed using the five allergic patient's era either by testing them individually or as a pool. Results: Four out of five patients recognized a low-molecular-mass protein (around 13kDa) by immunoblotting of the flaxseed extract, while two patients recognized a protein of approximately 55 kDa. They were identified by mass spectrometry as flaxseed 2S albumin, included into WHO/IUIS allergen nomenclature as Lin u 1,and 11S globulin, respectively. Inhibition assays revealed in vitro IgE-cross-reactivity of Lin u 1 with peanut and cashew nut proteins, while IgE recognition of 11S globulin by patients' sera was partially inhibited by several plant-derived sources. Conclusions Seed storage proteins from flaxseed were involved in the development of severe symptoms in five individuals and exhibited cross-reactivity with other allergenic sources. Besides the severity of flaxseed allergy in patients sensitized to 2S albumin, it is the first time that the 11S globulin is identified as a potential allergen. We consider that these data should be taken into account for a more accurate diagnosis of patients.

Maria Luisa Somoza1 *, Natalia Pérez-Sánchez2 *, Isabel Torres-Rojas,1 Laura Martín-Pedraza,3 Natalia Blanca-López,1 Laura Victorio Puche,4 Eva Abel Fernández González,5 José Damián López Sánchez,6 Javier Fernández-Sánchez,7,8 Enrique Fernández-Caldas,5,9 Mayte Villalba,10 Francisco Javier Ruano,1 José Antonio Cornejo-García11 *, Gabriela Canto1,12 *, Miguel Blanca3 &#x002A1Allergy Department, Infanta Leonor University Hospital, Madrid, Spain; 2Allergy Department, Hospital Regional Universitario de Málaga, Málaga-IBIMA (FIMABIS), Málaga, Spain; 3Allergy Department, Fundación para la Investigación e Innovación Biomédica (FIIB) de los Hospitales Universitarios Infanta Leonor y Sureste, Madrid, Spain; 4Allergy Department, Morales Meseguer General University Hospital, Murcia, Spain; 5R&D Department, Inmunotek Laboratories, Madrid, Spain; 6Allergy Department, Virgen de la Arrixaca Clinical University Hospital, Murcia, Spain; 7Allergy Department, General University Hospital of Alicante- ISABIAL, Alicante, Spain; 8Clinical Medicine Department, Miguel Hernandez University, Alicante, Spain; 9Division of Allergy and Immunology, University of South Florida College of Medicine, Tampa, FL, USA; 10Department of Biochemistry and Molecular Biology, Universidad Complutense de Madrid, Madrid, Spain; 11Instituto de Investigación Biomédica de Málaga-IBIMA (FIMABIS), Málaga, Spain; 12School of Medicine, Universidad Complutense de Madrid, Madrid, Spain*These authors contributed equally to this workCorrespondence: Maria Luisa Somoza, Email mlsomoza@yahoo.comBackground: Allergy can start at early ages, with genetic and environmental factors contributing to its development.Aim: The study aimed to describe the pattern of sensitisation and allergy in children and adolescents of Spanish versus Moroccan ancestry but born in the same rural area of Spain.Methods: Participants were children and adolescents (3– 19 years) of Spanish or Moroccan descent, born in Blanca, Murcia (Spain). A detailed questionnaire was completed, and skin prick tests were performed to assess reactions to the most prevalent pollen allergens (O. europaea, P. pratense, S. kali, C. arizonica, P. acerifolia, A. vulgaris and P. judaica) plus molecular components Ole e 1 and Ole e 7. The association with ancestry was verified by studying participants’ parents.Results: The study included 693 participants: 48% were aged 3– 9 years and 52%, 10– 19 years; 80% were of Spanish descent and 20% of Moroccan descent. Sensitisation to Olea europaea, Phleum pratense, Salsola kali and Cupressus arizonica were slightly higher in the Spanish group. The only significant differences were observed in sensitisation to Ole e 1 (p=0.02). Rhinitis, conjunctivitis, and rhinitis plus asthma were significantly higher in the Spanish group (p=0.03, p=0.02, p=0.007, respectively). The sensitisation pattern differed between Spanish and Moroccan parents, and between Moroccan parents and their children, but not between Spanish parents and their children.Conclusion: Both environment and ancestry may influence sensitisation and symptoms. Although the environment seems to have a stronger influence, other factors may contribute to the differences in prevalence and in the clinical entities in people of Spanish versus Moroccan descent.Keywords: ancestry, pollen sensitisation, children/adolescents, olive tree pollen, molecular components, respiratory allergy

The COVID-19 pandemic and associated lockdown measures have been associated with substantial disruptions to health care services, including screening for human immunodeficiency virus (HIV) and management of people living with HIV (PLWH). Data from 3265 patients were examined in a retrospective cohort study. We compared outpatient follow-up for PLWH, the number of new patients, treatment adherence, hospitalizations, and deaths during the “pandemic period” (March 2020 to February 2021), the “pre-pandemic period” (the equivalent time frame in 2019), and the “post-pandemic period” (March to September 2021). During the pandemic period, the number of new patients seen at the HIV clinic (116) as well as the requested viral load tests (2414) decreased significantly compared to the pre-pandemic (204 and 2831, respectively) and post-pandemic periods (146 and 2640, respectively) (p < 0.01 for all the comparisons). However, across the three study periods, the number of drug refills (1385, 1330, and 1411, respectively), the number of patients with undetectable viral loads (85%, 90%, and 93%, respectively), and the number of hospital admissions among PLWH remained constant. Despite the COVID-19 pandemic’s impact, our findings show stability in the retention of clinical care, adherence to treatment, and viral suppression of PLWH, with no significant impact on hospitalization rates or all-cause mortality.

The COVID-19 pandemic and associated lockdown measures have been associated with substantial disruptions to health care services, including screening for human immunodeficiency virus (HIV) and management of people living with HIV (PLWH). Methods: Data from 3265 patients were examined in a retrospective cohort study. We compared outpatient follow-up for PLWH, the number of new patients, treatment adherence, hospitalizations, and deaths during the “pandemic period” (March 2020 to February 2021) to the “pre-pandemic period” (the equivalent timeframe in 2019) and the “post-pandemic period” (March to September 2021). Results: During the pandemic period, the number of new patients seen at the HIV clinic (116), as well as the requested viral load tests (2414), decreased significantly compared to the pre-pandemic (204 and 2831, respectively) and post-pandemic periods (146 and 2640, respectively)(p

The most important peach fruit allergen is Pru p 3, followed by Pru p 1, Pru p 4, and Pru p 7. We aimed to assess their role in subjects with peach fruit-induced allergy (anaphylaxis and OAS) and compare skin prick tests (SPT) vs. specific immunoglobulin E (sIgE) for predicting anaphylaxis. We also selected a control group. SPT included prevalent inhalant and plant food allergens plus peach peel extract. The sIgE to Pru p 1, Pru p 3, Pru p 4, and Pru p 7 were quantified. Compared with controls (n = 42), cases (n = 41) were younger (P = 0.003), more frequently female (P < 0.05) and had higher SPT positivity to peach peel (44% vs. 2.4%, P < 0.0001). There were significant differences in sensitization to several pollens: Olea europaea, Artemisia vulgaris, Prunus persica, Platanus acerifolia (all P < 0.001); and fruits: apple (P < 0.04), peanut (P < 0.002), tomato (P < 0.005), and melon (P < 0.05). Pru p 3 sIgE was detected in 61% of all cases (85% anaphylaxis and 38% OAS; P < 0.01 each) and 5% of controls (P < 0.001). Pru p 4 sIgE was present in 19% of cases and 7% of controls. The sIgE to Pru p 1 and Pru p 7 were not found. The odds ratio to predict anaphylaxis for peach peel SPT was 113 (confidence interval [CI], 20-613; P < 0.0001); for sIgE to Pru p 3, 22 (CI, 5.3-93; P < 0.0001); and for SPT positivity to selected plant food allergens, 5 (CI, 1-19; P < 0.05). In our study group, SPT with peel peach extract was a better predictor of anaphylaxis than Pru p 3 sIgE or other variables considered. The role of sIgE to Pru p 1, Pru p 4, and Pru p 7 seemed negligible.

Peach tree allergens are present in fruit, pollen, branches, and leaves, and can induce systemic, respiratory, cutaneous, and gastrointestinal symptoms. We studied the capacity of peach fruit/Pru p 1, Pru p 3, Pru p 4, Pru p 7 and peach pollen/Pru p 9 for inducing symptoms following oral or respiratory exposure in a large group of subjects. We included 716 adults (aged 21 to 83 y.o.) exposed to peach tree pollen and fruit intake in the study population. Participants completed a questionnaire and were skin tested with a panel of inhalant and food allergens, including peach tree pollen, Pru p 9 and peach fruit skin extract. Immunoglobulin E antibodies (SIgE) to Pru p 1, Pru p 3, Pru p 4 and Pru p 7 were quantified. Sensitised subjects underwent oral food challenge with peach fruit and nasal provocation test with peach tree pollen and Pru p 9. The prevalence of sensitisation to peach fruit was 5% and most of these had SIgE to Pru p 3, with a very low proportion to Pru p 4 SIgE and no SIgE to Pru p 1 and Pru p 7. In only 1.8%, anaphylaxis was the clinical entity induced. Cases with positive skin tests to peach and SIgE to Pru p 3 presented a good tolerance after oral challenge with peach fruit. The prevalence of skin sensitisation to peach tree pollen was 22%, with almost half recognising Pru p 9. This induced respiratory symptoms in those evaluated by nasal provocation. In a large population group exposed to peach fruit and peach tree pollen, most individuals were tolerant, even in those with SIgE to Pru p 3. A positive response to Pru p 9 was associated with respiratory allergy.

This review searched for published evidence that could explain how different physicochemical properties impact on the allergenicity of food proteins and if their effects would follow specific patterns among distinct protein families. Owing to the amount and complexity of the collected information, this literature overview was divided in two articles, the current one dedicated to protein families of plant allergens and a second one focused on animal allergens. Our extensive analysis of the available literature revealed that physicochemical characteristics had consistent effects on protein allergenicity for allergens belonging to the same protein family. For example, protein aggregation contributes to increased allergenicity of 2S albumins, while for legumins and cereal prolamins, the same phenomenon leads to a reduction. Molecular stability, related to structural resistance to heat and proteolysis, was identified as the most common feature promoting plant protein allergenicity, although it fails to explain the potency of some unstable allergens (e.g. pollen-related food allergens). Furthermore, data on physicochemical characteristics translating into clinical effects are limited, mainly because most studies are focused on in vitro IgE binding. Clinical data assessing how these parameters affect the development and clinical manifestation of allergies is minimal, with only few reports evaluating the sensitising capacity of modified proteins (addressing different physicochemical properties) in murine allergy models. In vivo testing of modified pure proteins by SPT or DBPCFC is scarce. At this stage, a systematic approach to link the physicochemical properties with clinical plant allergenicity in real-life scenarios is still missing., The authors highly appreciate the support from the European Cooperation in Science and Technology (COST) Office. This article is based upon work from COST Action FA1402, supported by COST (www.cost.eu). This work was also supported by Fundação para a Ciência e Tecnologia under the Partnership Agreement UIDB 50006/2020 and by the projects AlleRiskAssess - PTDC/BAA-AGR/31720/2017 and NORTE-01-0145-FEDER-00001. C.V. is grateful to FCT grants (PD/BD/114576/2016) financed by POPH-QREN (subsidised by FSE and MCTES). T.C.V. is grateful to the Ministry of Education, Science and Technological Development of the Republic of Serbia through grant number OI172024. P.M.R. and D.S. are grateful to FCT through project UIDB/04326/2020 and Mar2020 16–02-01-FMP-0014 – ‘ALLYFISH’. J.K. and A.K. acknowledge the PRIDE program grant (PRIDE/11012546/NEXTIMMUNE) by the Fonds National de la Recherche (FNR), Luxembourg and a translational grant (APSIS, PMC/2017/02) by the Personalised Medicine Consortium (PMC), Luxembourg.

The influence of gastrointestinal digestion on the immunological properties of three different nonspecific lipid-transfer proteins (nsLTPs) described in tomato fruit has been assessed using an in vitro system mimicking the stomach and intestine digestion conditions. Tomato peel/pulp nsLTP, Sola l 3, was degraded after digestion, although the immunoglobulin E (IgE) recognition of intact protein and a 10 kDa band were still observed after 30 min of duodenal digestion in the presence of phosphatidylcholine. The tomato seed nsLTP, Sola l 7, showed a higher stability than the other seed allergen, Sola l 6, during digestion. Sola l 7 showed an IgE immunoreactive 6.5 kDa band in immunoblotting analysis, retaining up to 7% of its IgE-binding capacity in inhibition ELISA test after 60 min of duodenal digestion and keeping intact its ability to activate basophils after digestion. These results suggest that the tomato seed allergen Sola l 7 might be considered as an important allergen in the induction of allergic responses to tomato due to its high stability against gastrointestinal digestion., This work was supported by grants SAF2017-86483-R from the Ministerio de Economía y Competitividad and PI13/00928 Instituto de Salud Carlos III (ISCIII), ISCIII cofounded by Fondo Europeo de Desarrollo Regional – FEDER for the Thematic Networks and Co-operative Research Centres; RIRAAF RD16/0006/0024 and ARADyAL (RD16/0006/0001; RD16/0006/0013; RD16/0006/0014); and EAACI Exchange Research Fellowship 2016. The authors would like to thank the excellent technical support of Sara Abián. S.B. was supported by a Juan de la Cierva Incorporación contract from the Spanish Ministerio de Ciencia, Innovación y Universidades.

Covid-19, caused by the SARS-CoV-2 virus, has reached the category of a worldwide pandemic. Even though intensive efforts, no effective treatments or a vaccine are available. Molecular characterization of the transcriptional response in Covid-19 patients could be helpful to identify therapeutic targets. In this study, RNAseq data from peripheral blood mononuclear cell samples from Covid-19 patients and healthy controls was analyzed from a functional point of view using probabilistic graphical models. Two networks were built: one based on genes differentially expressed between healthy and infected individuals and another one based on the 2,000 most variable genes in terms of expression in order to make a functional characterization. In the network based on differentially expressed genes, two inflammatory response nodes with different tendencies were identified, one related to cytokines and chemokines, and another one related to bacterial infections. In addition, differences in metabolism, which were studied in depth using Flux Balance Analysis, were identified. SARS-CoV2-infection caused alterations in glutamate, methionine and cysteine, and tetrahydrobiopterin metabolism. In the network based on 2,000 most variable genes, also two inflammatory nodes with different tendencies between healthy individuals and patients were identified. Similar to the other network, one was related to cytokines and chemokines. However, the other one, lower in Covid-19 patients, was related to allergic processes and self-regulation of the immune response. Also, we identified a decrease in T cell node activity and an increase in cell division node activity. In the current absence of treatments for these patients, functional characterization of the transcriptional response to SARS-CoV-2 infection could be helpful to define targetable processes. Therefore, these results may be relevant to propose new treatments.

Peach tree (PT) pollen sensitization is highly prevalent in subjects living in areas where this tree is widely cultivated. None of the allergens responsible for these sensitizations have been identified so far. Our aim was to identify the most relevant PT pollen allergens and analyze their capacity for inducing respiratory symptoms. We studied sixty-two individuals sensitized to PT pollen who developed symptoms after its exposure. The IgE binding profile on peach pollen extract by means of immunoblotting using sera from these subjects was analyzed. Protein extract was fractionated by anion-exchange chromatography and HPLC, fractions run in SDS-PAGE and proteins were identified from IgE-binding bands by mass spectrometry. Several allergenic proteins in the PT pollen extract were recognized by patients' IgE: a glucan endo-1,3-beta-glucosidase-like, a polygalacturonase, an UTP-glucose-1-phosphate uridylyltransferase and a PR-1a protein. This PR-1a protein is a novel allergen frequently recognized with a molecular mass of 18 kDa, named as Pru p 9 following the WHO-IUIS nomenclature. Skin Prick Test (SPT) performed with this allergen was positive in 41% of the PT pollen-sensitized clinical cases. Most of them had rhinitis or rhinoconjunctivitis, but a significant percentage experienced asthma with seasonal symptoms during the period of PT flowering. Nasal Provocation test (NPT) with Pru p 9 was positive in all cases with positive SPT to this new allergen eliciting nasal symptoms similar to those challenged with PT pollen. We demonstrate that PT pollen can induce sensitization and allergy in an exposed population, being Pru p 9 a relevant allergen responsible of respiratory symptoms. Considering the extensive peach worldwide production with a large number of people involved, our results add a great value for the diagnosis and management of subjects allergic to this pollen.

A novel and disposable electrochemical biosensor for PCR-free and selective detection of Sola l 7, a non-specific lipid transfer protein (nsLTP) found in tomato seeds associated to severe symptoms of tomato-allergic patients, is reported in this work. The methodology involves the formation of DNA/RNA heterohybrids by sandwich hybridization of a specific fragment of the Sola l 7 allergen coding sequence with appropriate RNA probes designed and described for the first time in this work. Labeling was carried out with commercial antibodies specific to the heteroduplexes and secondary antibodies conjugated with HRP onto the surface of magnetic beads. Amperometric transduction was performed upon magnetic capture of the resulting magnetic bioconjugates on screen-printed electrodes using the system H2O2/HQ. A comparison of the sandwich hybridization format with a direct approach as well as between different labeling strategies was performed. The LOD value achieved was 0.2 pM (5 amol in 25 μL). The biosensor was successfully applied to the selective analysis of the targeted Sola l 7 specific region directly in just 100 ng of non-fragmented denatured genomic DNA extracted from tomato seeds., The financial support of the Spanish Ministerio de Economía y Competitividad Research Projects, CTQ2015-64402-C2-1-R, SAF2017-86483-R and the TRANSNANOAVANSENS Program from the Comunidad de Madrid (Grant P2018/NMT-4349) are gratefully acknowledged. M.F.B. is grateful to FCT grant SFRH/BPD/78845/2011,financed by POPH–QREN–Tipologia4.1–Formação Avançada, subsidized by Fundo Social Europeu and Ministério da Ciência, Tecnologiae Ensino Superior. The author M.A.P.B. is grateful to the authors J.M.R., M.F.B., S.C., J.M.P. for the scientific assistance and suggestions shared throughout the supervision of her Master’s project and Master’s thesis at University of Minho. The author M.A.P.B. also acknowledges the Department of Biology (DB) and the Centre of Molecular and Environmental Biology (CBMA) from University of Minho (UM), Braga,Portugal, by providing all the conditions leading to the Master's thesis in“Biophysics and Bionanosystems”. Financial support of M.A.P.B. forthis work was provided by a fellowship within the programme Erasmus+ scholarship/Portugal, which allowed performing the laboratorial work at the University Complutense of Madrid, Madrid, Spain. The author J.M.R. acknowledges CBMA-UM and DB-UM, Portugal, by the conditions provided. J.M.R. is also grateful to the Green Chemistry Laboratory (LAQV)–Research center Chemistry and Technology Network (REQUIMTE), and the Department of Chemistry and Biochemistry (DCB) from Faculty of Sciences, University of Porto(FCUP), Porto, Portugal, where currently he is researcher. J.M.R. acknowledges the financial support of the strategic programmes UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) and PTDC/SAUNUT/30448/2017 (POCI-01-0145-FEDER-030448) and M.F.B. the financial support of the projects PTDC/QUI-QAN/30735/2017 and UID/QUI/50006/2019, funded by national funds through Fundação para a Ciência e Tecnologia [Foundation for Science and Technology](FCT-I.P.)/Ministério da Ciência, Tecnologia e Ensino Superior [Ministry of Science, Technology and Higher Education] (MCTES), and Fundo Europeu de Desenvolvimento Regional [European RegionalDevelopment Fund] (FEDER), under the scope of the COMPETE2020–Programa Operacional Competitividade e Internacionalização[COMPETE2020–Competitiveness and InternationalizationOperational Program, POCI]. S.B. acknowledges the financial support from MINECO through the“Juan de la Cierva” program.

[This corrects the article DOI: 10.1371/journal.pone.0230010.].

Prevalence of food-induced anaphylaxis increase progressively and occurs in an unpredictable manner, seriously affecting the quality of life of patients. Intrinsic factors including age, physiological and genetic features of the patient as well as extrinsic factors such as the intake of drugs and exposure to environmental agents modulate this disorder. It has been proven that diseases such as mastocytosis, defects in HLA or filaggrin genes, increase the risk of severe allergic episodes. Certain allergen families such as storage proteins, lipid transfer proteins (LTPs), or parvalbumins have also been linked to anaphylaxis. Environmental factors such as inhaled allergens or sensitization through the skin can exacerbate or trigger acute anaphylaxis. Moreover, the effect of dietary habits such as the early introduction of certain foods in the diet, and the advantage of the breast-feeding remain as yet unresolved. Interaction of allergens with the intestinal cell barrier together with a set of effector cells represent the primary pathways of food-induced anaphylaxis. After an antigen cross-links the IgEs on the membrane of effector cells, a complex intracellular signalling cascade is initiated which leads cells to release pre-formed mediators stored in their granules that are responsible for the acute symptoms of anaphylaxis. Afterwards they can also rapidly synthesize lipid compounds such as prostaglandins or leukotrienes. Cytokines or chemokines are also released, leading to the recruitment and activation of immune cells in the inflammatory microenvironment. Multiple factors that affect food-induced anaphylaxis are discussed in this review, paying special attention to dietary habits and environmental and genetic conditions.

Rationale Food allergy is an increasing health problem with many proteins involved that belong mainly to a limited number of families. They show a high level of cross-reactivity. In the Mediterranean area, the most prevalent food allergens are those of vegetal origin. Although tomato (Solanum lycopersium L.) is one of the implicated foods, studies on the identification and relevance of their allergens have not been carried out in detail. This could be particularly relevant for tomato seeds as happen in other fruits like kiwi. The aimed was to analyse the sensitisation pattern to tomato seeds in patients from two hospitals integrated in the RIRAAF.

Key determinants for the development of an allergic response to an otherwise ‘harmless’ food protein involve different factors like the predisposition of the individual, the timing, the dose, the route of exposure, the intrinsic properties of the allergen, the food matrix (e.g. lipids) and the allergen modification by food processing. Various physicochemical parameters can have an impact on the allergenicity of animal proteins. Following our previous review on how physicochemical parameters shape plant protein allergenicity, the same analysis was proceeded here for animal allergens., We found that each parameter can have variable effects, ranging on an axis from allergenicity enhancement to resolution, depending on its nature and the allergen. While glycosylation and phosphorylation are common, both are not universal traits of animal allergens. High molecular structures can favour allergenicity, but structural loss and uncovering hidden epitopes can also have a similar impact. We discovered that there are important knowledge gaps in regard to physicochemical parameters shaping protein allergenicity both from animal and plant origin, mainly because the comparability of the data is poor. Future biomolecular studies of exhaustive, standardised design together with strong validation part in the clinical context, together with data integration model systems will be needed to unravel causal relationships between physicochemical properties and the basis of protein allergenicity., The authors highly appreciate the support from the COST Office. This article is based upon work from COST Action FA1402, supported by COST (European Cooperation in Science and Technology, www.cost.eu). This work was also supported by Fundação para a Ciência e Tecnologia under the Partnership Agreement UIDB 50006/2020 and by the projects AlleRiskAssess—PTDC/BAA-AGR/31720/2017. C.V. is grateful to FCT grant (PD/BD/114576/2016) financed by POPH-QREN (subsidised by FSE and MCTES). J.C. acknowledges FCT for the research contract (SFRH/BPD/102404/2014). T.C.V. is grateful to the Ministry of Education, Science and Technological Development of the Republic of Serbia through grant number OI172024. P.M.R. and D.S. are grateful to FCT through project UIDB/04326/2020 and Mar2020 16-02-01-FMP-0014—“ALLYFISH”. J.K. and A.K. acknowledge PRIDE program grants (PRIDE/11012546/NEXTIMMUNE). J.K. also acknowledges FNR (Fonds National de la Recherche) and the PMC (Personalised Medicine Consortium).