Food Allergy (FA) is now one of the most common chronic diseases of childhood often lasting throu... more Food Allergy (FA) is now one of the most common chronic diseases of childhood often lasting throughout life and leading to significant worldwide healthcare burden. The precise mechanisms responsible for the development of this inflammatory condition are largely unknown; however, a multifactorial aetiology involving both environmental and genetic contributions is well accepted. A precise understanding of the pathogenesis of FA is an essential first step to developing comprehensive prevention strategies that could mitigate this epidemic. As it is frequently preceded by atopic dermatitis and can be prevented by early antigen introduction, the development of FA is likely facilitated by the improper initial presentation of antigen to the developing immune system. Primary oral exposure of antigens allowing for presentation via a well-developed mucosal immune system, rather than through a disrupted skin epidermal barrier, is essential to prevent FA. In this review, we present the data supporting the necessity of 1) an intact epidermal barrier to prevent epicutaneous antigen presentation, 2) the presence of specific commensal bacteria to maintain an intact mucosal immune system and 3) maternal/infant diet diversity, including vitamins and minerals, and appropriately timed allergenic food introduction to prevent FA.
Food allergy is an increasingly prevalent disease driven by uncontrolled type 2 immune response. ... more Food allergy is an increasingly prevalent disease driven by uncontrolled type 2 immune response. Currently, knowledge about the underlying mechanisms that initiate and promote the immune response to dietary allergens is limited. Patients with food allergy are commonly sensitized through the skin in their early life, later on developing allergy symptoms within the gastrointestinal tract. Food allergy results from a dysregulated type 2 response to food allergens, characterized by enhanced levels of IgE, IL‐4, IL‐5, and IL‐13 with infiltration of mast cells, eosinophils, and basophils. Recent studies raised a possible role for the involvement of innate lymphoid cells (ILCs) in driving food allergy. Unlike lymphocytes, ILCs lack They represent a group of lymphocytes that lack specific antigen receptors. ILCs contribute to immune responses not only by releasing cytokines and other mediators but also by responding to cytokines produced by activated cells in their local microenvironment. Due to their localization at barrier surfaces of the airways, gut, and skin, ILCs form a link between the innate and adaptive immunity. This review summarizes recent evidence on how skin and gastrointestinal mucosal immune system contribute to both homeostasis and the development of food allergy, as well as the involvement of ILCs toward inflammatory processes and regulatory mechanisms.
The coronavirus disease 2019 (COVID‐19) has evolved into a pandemic infectious disease transmitte... more The coronavirus disease 2019 (COVID‐19) has evolved into a pandemic infectious disease transmitted by the severe acute respiratory syndrome coronavirus (SARS‐CoV‐2). Allergists and other healthcare providers (HCPs) in the field of allergies and associated airway diseases are on the front line, taking care of patients potentially infected with SARS‐CoV‐2. Hence, strategies and practices to minimize risks of infection for both HCPs and treated patients have to be developed and followed by allergy clinics.
The Journal of Allergy and Clinical Immunology: In Practice
Regional and national legislation mandates the disclosure of "priority" allergens when ... more Regional and national legislation mandates the disclosure of "priority" allergens when present as an ingredient in foods, but this does not extend to the unintended presence of allergens due to shared production facilities. This has resulted in a proliferation of precautionary allergen ("may contain") labels (PAL) which are frequently ignored by food-allergic consumers. Attempts have been made to improve allergen risk management to better inform the use of PAL, but a lack of consensus has led to variety of regulatory approaches and non-uniformity in the use of PAL by food businesses. One potential solution would be to establish internationally-agreed "reference doses", below which no PAL would be needed. However, if reference doses are to be used to inform the need for PAL, then it is essential to characterize the hazard associated with these low-level exposures. For peanut, there are now published data relating to over 3000 double-blind, placebo-controlled challenges in allergic individuals, but a similar level of evidence is lacking for other priority allergens. We present the results of a rapid evidence assessment and meta-analysis for the risk of anaphylaxis to low-level allergen exposure for priority allergens. On the basis of this analysis, we propose that peanut can and should be considered an exemplar allergen for the hazard characterization at low-level allergen exposure.
BACKGROUND Peanut, tree nut, and sesame allergies are responsible for most life-threatening food-... more BACKGROUND Peanut, tree nut, and sesame allergies are responsible for most life-threatening food-induced allergic reactions. Rates of coexistent allergy between these foods have been from mostly retrospective studies that include only a limited number of tree nuts or were not based on oral food challenges. OBJECTIVE The Pronuts study is a multicenter European study (London, Geneva, and Valencia) assessing the challenge-proven rate of coexistent peanut, tree nut, and/or sesame seed allergy. METHODS Children aged 0 to 16 years with at least 1 confirmed nut or sesame seed allergy underwent sequential diagnostic food challenges to all other nuts and sesame seed. RESULTS Overall, the rate of coexistent peanut, tree nut, and sesame seed allergy was 60.7% (n = 74/122; 95% CI, 51.4% to 69.4%). Peanut allergy was more common in London, cashew and pistachio nut allergies were more common in Geneva, and walnut and pecan allergies were more common in Valencia. Strong correlations were found between cashew-pistachio, walnut-pecan, and walnut-pecan-hazelnut-macadamia clusters. Age (>36 months) and center (Valencia > Geneva > London) were associated with an increased odds of multiple nut allergies. By pursuing the diagnostic protocol to demonstrate tolerance to other nuts, participants were able to introduce a median of 9 nuts. CONCLUSION We found a higher rate of coexistent nut and sesame seed allergies than previously reported. Performing sequential food challenges was labor intensive and could result in severe allergic reactions; however, it reduced dietary restrictions. Age was a significant predictor of multiple nut allergies, and thus the secondary spread of nut allergies occurred in older children.
1Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden 2Depart... more 1Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden 2Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden 3Department of Dermatology and Allergy, Allergie‐Centrum‐ Charité, Charité ‐ Universitätsmedizin Berlin, Berlin, Germany 4Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden 5Department of Medical Sciences, Uppsala University, Uppsala, Sweden 6Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden 7Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
The journal of allergy and clinical immunology. In practice
Various in vitro tests assess different aspects of the underlying immune mechanism of IgE-mediate... more Various in vitro tests assess different aspects of the underlying immune mechanism of IgE-mediated food allergy. Some can be used for diagnostic purposes; specific IgE to allergen extracts is widely available; specific IgE to allergen components is used in most specialist centers, and the basophil activation test is becoming increasingly used clinically. IgE to allergen peptides, T-cell assays, allergen-specific/total IgE ratios, and allergen-specific IgG4/IgE ratios are currently reserved for research. Different factors can modulate the likelihood of IgE-mediated food allergy of a given allergy test result, namely, the patients' age, ethnicity, previous allergic reaction to the identified food, concomitant atopic conditions, and geographical location, and need to be taken into account when interpreting the allergy test results in the clinic. The importance of the specific food, the clinical resources available, and patient preferences are additional aspects that need to be cons...
The Journal of Allergy and Clinical Immunology: In Practice, 2016
Peanut and tree nut allergies have become a public health problem over the last 2 decades. The di... more Peanut and tree nut allergies have become a public health problem over the last 2 decades. The diagnostic procedure relies on a suggestive history, as well as on evidence of sensitization (skin prick testing and/or specific IgE blood testing), followed in selected cases by a food challenge. Standard IgE tests may be positive to more than 1 nut, due to cross-reactivity (allergens common to several nuts) or cosensitivity (frequently associated positive test results without cross-reactivity). Thus, many patients with a peanut or a tree nut allergy avoid all nuts, relying on positive test results without clinical evidence of reactivity. In addition, coexisting pollen sensitivity may add to diagnostic uncertainty due to potential cross-reactivity between pollens and nuts. In this article, we discuss challenges in diagnosis and clinical management of peanut and tree nut allergy related to cross-reactivity and cosensitization, as well as the avoidance of nuts tested positive to reduce the risk of reactions by cross-contamination. Studies to provide more accurate characterization of genuine clinically relevant cross-reactivity or cosensitivity to multiple nuts are needed.
Antihistamines are commonly used in paediatric medicine mainly for the treatment of allergic cond... more Antihistamines are commonly used in paediatric medicine mainly for the treatment of allergic conditions. First generation antihistamines have been in use for many years, despite limited research studies supporting their use. Second generation antihistamines have been investigated for both efficacy and safety in paediatrics. An optimal understanding of their effects and pharmacology are required for optimal use in each patient. In this review we discuss the indications for use, as well as efficacy and safety of both old and newer antihistamines for the paediatric population.
Background We hypothesized that filaggrin (FLG) loss-of-function mutations modify the effect of a... more Background We hypothesized that filaggrin (FLG) loss-of-function mutations modify the effect of allergen exposure on the development of allergic sensitization. Objective We sought to determine whether early-life exposure to inhalant allergens increases the risk of specific sensitization and whether FLG mutations modulate these odds. Methods In a population-based birth cohort we measured mite, cat, and dog allergen levels in dust samples collected from homes within the first year of life. Sensitization was assessed at 6 time points between infancy and age 16 years. Genotyping was performed for 6 FLG mutations. Results In the longitudinal multivariable model (age 1-16 years), we observed a significant interaction between FLG and Fel d 1 exposure on cat sensitization, with the effect of exposure being significantly greater among children with FLG mutations compared with those without (odds ratio, 1.36; 95% CI, 1.02-1.80; P = .035). The increase in risk of mite sensitization with increasing Der p 1 exposure was consistently greater among children with FLG mutations, but the interaction did not reach statistical significance. Different associations were observed for dogs: there was a significant interaction between FLG and dog ownership, but the risk of sensitization to any allergen was significantly lower among children with FLG mutations who were exposed to a dog in infancy (odds ratio, 0.16; 95% CI, 0.03-0.86; P = .03). Conclusions FLG loss-of-function mutations modify the relationship between allergen exposure and sensitization, but effects differ at different ages and between different allergens.
Food Allergy (FA) is now one of the most common chronic diseases of childhood often lasting throu... more Food Allergy (FA) is now one of the most common chronic diseases of childhood often lasting throughout life and leading to significant worldwide healthcare burden. The precise mechanisms responsible for the development of this inflammatory condition are largely unknown; however, a multifactorial aetiology involving both environmental and genetic contributions is well accepted. A precise understanding of the pathogenesis of FA is an essential first step to developing comprehensive prevention strategies that could mitigate this epidemic. As it is frequently preceded by atopic dermatitis and can be prevented by early antigen introduction, the development of FA is likely facilitated by the improper initial presentation of antigen to the developing immune system. Primary oral exposure of antigens allowing for presentation via a well-developed mucosal immune system, rather than through a disrupted skin epidermal barrier, is essential to prevent FA. In this review, we present the data supporting the necessity of 1) an intact epidermal barrier to prevent epicutaneous antigen presentation, 2) the presence of specific commensal bacteria to maintain an intact mucosal immune system and 3) maternal/infant diet diversity, including vitamins and minerals, and appropriately timed allergenic food introduction to prevent FA.
Food allergy is an increasingly prevalent disease driven by uncontrolled type 2 immune response. ... more Food allergy is an increasingly prevalent disease driven by uncontrolled type 2 immune response. Currently, knowledge about the underlying mechanisms that initiate and promote the immune response to dietary allergens is limited. Patients with food allergy are commonly sensitized through the skin in their early life, later on developing allergy symptoms within the gastrointestinal tract. Food allergy results from a dysregulated type 2 response to food allergens, characterized by enhanced levels of IgE, IL‐4, IL‐5, and IL‐13 with infiltration of mast cells, eosinophils, and basophils. Recent studies raised a possible role for the involvement of innate lymphoid cells (ILCs) in driving food allergy. Unlike lymphocytes, ILCs lack They represent a group of lymphocytes that lack specific antigen receptors. ILCs contribute to immune responses not only by releasing cytokines and other mediators but also by responding to cytokines produced by activated cells in their local microenvironment. Due to their localization at barrier surfaces of the airways, gut, and skin, ILCs form a link between the innate and adaptive immunity. This review summarizes recent evidence on how skin and gastrointestinal mucosal immune system contribute to both homeostasis and the development of food allergy, as well as the involvement of ILCs toward inflammatory processes and regulatory mechanisms.
The coronavirus disease 2019 (COVID‐19) has evolved into a pandemic infectious disease transmitte... more The coronavirus disease 2019 (COVID‐19) has evolved into a pandemic infectious disease transmitted by the severe acute respiratory syndrome coronavirus (SARS‐CoV‐2). Allergists and other healthcare providers (HCPs) in the field of allergies and associated airway diseases are on the front line, taking care of patients potentially infected with SARS‐CoV‐2. Hence, strategies and practices to minimize risks of infection for both HCPs and treated patients have to be developed and followed by allergy clinics.
The Journal of Allergy and Clinical Immunology: In Practice
Regional and national legislation mandates the disclosure of "priority" allergens when ... more Regional and national legislation mandates the disclosure of "priority" allergens when present as an ingredient in foods, but this does not extend to the unintended presence of allergens due to shared production facilities. This has resulted in a proliferation of precautionary allergen ("may contain") labels (PAL) which are frequently ignored by food-allergic consumers. Attempts have been made to improve allergen risk management to better inform the use of PAL, but a lack of consensus has led to variety of regulatory approaches and non-uniformity in the use of PAL by food businesses. One potential solution would be to establish internationally-agreed "reference doses", below which no PAL would be needed. However, if reference doses are to be used to inform the need for PAL, then it is essential to characterize the hazard associated with these low-level exposures. For peanut, there are now published data relating to over 3000 double-blind, placebo-controlled challenges in allergic individuals, but a similar level of evidence is lacking for other priority allergens. We present the results of a rapid evidence assessment and meta-analysis for the risk of anaphylaxis to low-level allergen exposure for priority allergens. On the basis of this analysis, we propose that peanut can and should be considered an exemplar allergen for the hazard characterization at low-level allergen exposure.
BACKGROUND Peanut, tree nut, and sesame allergies are responsible for most life-threatening food-... more BACKGROUND Peanut, tree nut, and sesame allergies are responsible for most life-threatening food-induced allergic reactions. Rates of coexistent allergy between these foods have been from mostly retrospective studies that include only a limited number of tree nuts or were not based on oral food challenges. OBJECTIVE The Pronuts study is a multicenter European study (London, Geneva, and Valencia) assessing the challenge-proven rate of coexistent peanut, tree nut, and/or sesame seed allergy. METHODS Children aged 0 to 16 years with at least 1 confirmed nut or sesame seed allergy underwent sequential diagnostic food challenges to all other nuts and sesame seed. RESULTS Overall, the rate of coexistent peanut, tree nut, and sesame seed allergy was 60.7% (n = 74/122; 95% CI, 51.4% to 69.4%). Peanut allergy was more common in London, cashew and pistachio nut allergies were more common in Geneva, and walnut and pecan allergies were more common in Valencia. Strong correlations were found between cashew-pistachio, walnut-pecan, and walnut-pecan-hazelnut-macadamia clusters. Age (>36 months) and center (Valencia > Geneva > London) were associated with an increased odds of multiple nut allergies. By pursuing the diagnostic protocol to demonstrate tolerance to other nuts, participants were able to introduce a median of 9 nuts. CONCLUSION We found a higher rate of coexistent nut and sesame seed allergies than previously reported. Performing sequential food challenges was labor intensive and could result in severe allergic reactions; however, it reduced dietary restrictions. Age was a significant predictor of multiple nut allergies, and thus the secondary spread of nut allergies occurred in older children.
1Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden 2Depart... more 1Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden 2Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden 3Department of Dermatology and Allergy, Allergie‐Centrum‐ Charité, Charité ‐ Universitätsmedizin Berlin, Berlin, Germany 4Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden 5Department of Medical Sciences, Uppsala University, Uppsala, Sweden 6Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, Uppsala, Sweden 7Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden
The journal of allergy and clinical immunology. In practice
Various in vitro tests assess different aspects of the underlying immune mechanism of IgE-mediate... more Various in vitro tests assess different aspects of the underlying immune mechanism of IgE-mediated food allergy. Some can be used for diagnostic purposes; specific IgE to allergen extracts is widely available; specific IgE to allergen components is used in most specialist centers, and the basophil activation test is becoming increasingly used clinically. IgE to allergen peptides, T-cell assays, allergen-specific/total IgE ratios, and allergen-specific IgG4/IgE ratios are currently reserved for research. Different factors can modulate the likelihood of IgE-mediated food allergy of a given allergy test result, namely, the patients' age, ethnicity, previous allergic reaction to the identified food, concomitant atopic conditions, and geographical location, and need to be taken into account when interpreting the allergy test results in the clinic. The importance of the specific food, the clinical resources available, and patient preferences are additional aspects that need to be cons...
The Journal of Allergy and Clinical Immunology: In Practice, 2016
Peanut and tree nut allergies have become a public health problem over the last 2 decades. The di... more Peanut and tree nut allergies have become a public health problem over the last 2 decades. The diagnostic procedure relies on a suggestive history, as well as on evidence of sensitization (skin prick testing and/or specific IgE blood testing), followed in selected cases by a food challenge. Standard IgE tests may be positive to more than 1 nut, due to cross-reactivity (allergens common to several nuts) or cosensitivity (frequently associated positive test results without cross-reactivity). Thus, many patients with a peanut or a tree nut allergy avoid all nuts, relying on positive test results without clinical evidence of reactivity. In addition, coexisting pollen sensitivity may add to diagnostic uncertainty due to potential cross-reactivity between pollens and nuts. In this article, we discuss challenges in diagnosis and clinical management of peanut and tree nut allergy related to cross-reactivity and cosensitization, as well as the avoidance of nuts tested positive to reduce the risk of reactions by cross-contamination. Studies to provide more accurate characterization of genuine clinically relevant cross-reactivity or cosensitivity to multiple nuts are needed.
Antihistamines are commonly used in paediatric medicine mainly for the treatment of allergic cond... more Antihistamines are commonly used in paediatric medicine mainly for the treatment of allergic conditions. First generation antihistamines have been in use for many years, despite limited research studies supporting their use. Second generation antihistamines have been investigated for both efficacy and safety in paediatrics. An optimal understanding of their effects and pharmacology are required for optimal use in each patient. In this review we discuss the indications for use, as well as efficacy and safety of both old and newer antihistamines for the paediatric population.
Background We hypothesized that filaggrin (FLG) loss-of-function mutations modify the effect of a... more Background We hypothesized that filaggrin (FLG) loss-of-function mutations modify the effect of allergen exposure on the development of allergic sensitization. Objective We sought to determine whether early-life exposure to inhalant allergens increases the risk of specific sensitization and whether FLG mutations modulate these odds. Methods In a population-based birth cohort we measured mite, cat, and dog allergen levels in dust samples collected from homes within the first year of life. Sensitization was assessed at 6 time points between infancy and age 16 years. Genotyping was performed for 6 FLG mutations. Results In the longitudinal multivariable model (age 1-16 years), we observed a significant interaction between FLG and Fel d 1 exposure on cat sensitization, with the effect of exposure being significantly greater among children with FLG mutations compared with those without (odds ratio, 1.36; 95% CI, 1.02-1.80; P = .035). The increase in risk of mite sensitization with increasing Der p 1 exposure was consistently greater among children with FLG mutations, but the interaction did not reach statistical significance. Different associations were observed for dogs: there was a significant interaction between FLG and dog ownership, but the risk of sensitization to any allergen was significantly lower among children with FLG mutations who were exposed to a dog in infancy (odds ratio, 0.16; 95% CI, 0.03-0.86; P = .03). Conclusions FLG loss-of-function mutations modify the relationship between allergen exposure and sensitization, but effects differ at different ages and between different allergens.
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Papers by Helen Brough