Alpha-Gal Syndrome in Children: Peculiarities of a "Tick-Borne" Allergic Disease

Alpha-gal allergy in a South Asian country

BACKGROUND

Alpha gal syndrome (AGS) is a delayed allergy to red meat, due to IgE to galactose-alpha-1,3-galactose (alpha-gal). Sensitization occurs via tick bites. It has been described in the US, Europe, Australia, Japan and South Korea, but reports from the Indian subcontinent are rare. We report the demographics of alpha-gal allergy for the first time from the Indian subcontinent and possible association with vaccine allergy.

METHODS

Patients diagnosed with alpha-gal syndrome (AGS) from 2018 to 2024 were selected in this study. AGS was identified by the occurrence of allergic symptoms up to 8 h of ingestion of red meat, with positive serum IgE to alpha-gal > IgE to red meat, and negative IgE to BSA. Allergy to vaccines containing bovine products were also identified in patients with AGS.

RESULTS

Fifty-seven patients were identified. Thirty-one (54.3%) were 12 years or younger. There were more females among adults (63.2%) compared to children (50.0%), though statistically not significant. There was no difference between children and adults in relation to clinical features and time of onset of symptoms. However, 5/6 of adults with severe anaphylaxis (grade 5) were females. Six patients with AGS developed allergy, including anaphylaxis, to the measles, mumps, rubella (MMR, n = 3), rubella (n = 1), varicella (n = 1) and anti-rabies (n = 1) vaccines.

CONCLUSION

AGS is an important cause of food and vaccine allergy in the Indian subcontinent and is commoner in children unlike in other regions. However, the clinical features are similar to adults.

French Guiana and AGS: a path to uncovering hidden clues

INTRODUCTION

This article is a narrative review exploring how research in French Guiana could unlock the mysteries surrounding Alpha-Gal Syndrome (AGS), a recently identified IgE-mediated allergy with delayed reactions to exposure to non-Catarrhine mammalian-derived products. Although fewer than 10 cases have been reported across Latin America, two case series involving 11 and 18 patients with AGS have been documented in French Guiana.

AREAS COVERED

This article discusses risk factors such as ethnicity, prior pathogen-induced immunization to α-Gal, vectors responsible for AGS, their environment and ecosystems, observed phenotypes, and therapeutic implications for sensitized individuals. Literature research was based on PubMed between 12/2023 and 08/2024, using: α-Gal/Alpha-1,3-Galactose/galactose-α 1,3-galactose/Red meat allergy/Mammalian meat allergy/Alpha gal syndrome/Antivipmyn. Grey literature from French Guiana were obtained from Prof. Loïc Epelboin.

EXPERT OPINION

Advancing AGS research in French Guiana could yield valuable epidemiological insights, as existing data predominantly stem from European, North American, Australian, and Japanese contexts - regions with comparatively lower diversity in tick species, their mammalian hosts, associated pathogens, and parasitic infestations. Additionally, French Guiana presents unique therapeutic scenarios, such as Viperidae envenomation and transfusions under inventory constraints, that merit further investigation.

Alpha-gal syndrome and the gastrointestinal reaction: a narrative review

Gastrointestinal (GI) disturbances such as abdominal pain, nausea, and diarrhea are infrequently attributed to food allergies as an initial diagnosis in the absence of more traditional allergic reactions like hives, angioedema, or anaphylaxis. Alpha-gal syndrome (AGS) is an atypical and under-recognized allergy characterized by a delayed hypersensitivity reaction to the oligosaccharide galactose-α-1,3-galactose, a carbohydrate found in non-primate mammalian meat and derived products. This review of the current literature on AGS focuses on GI manifestations and diagnostic challenges. While clinical presentations of AGS vary widely, predominant or isolated GI symptoms, when manifested, can overlap with other disorders, thus making a timely and accurate diagnosis challenging. Here we provide an updated review of the epidemiology, pathophysiology, clinical presentation, and management of AGS. Current diagnostic approaches, treatment strategies, and areas requiring further research are also discussed.

Genetic and Immunological Insights into Tick-Bite Hypersensitivity and Alpha-Gal Syndrome: A Case Study Approach

Tick-bite hypersensitivity encompasses a range of clinical manifestations, from localized allergic reactions to systemic conditions like alpha-gal syndrome (AGS), an IgE-mediated allergy to galactose-α-1,3-galactose (α-Gal). This study investigated the clinical, molecular, immunological, and genetic features of two hypersensitivity cases. Two cases were analyzed: a 30-year-old woman with fixed drug reaction (FDR)-like hypersensitivity and a 10-year-old girl with AGS exhibiting borderline α-Gal-specific IgE. Diagnostic methods included allergen-specific IgE quantification, HLA genotyping, histopathological examination, and the molecular detection of tick-borne pathogens using microfluidic PCR. Case I demonstrated histopathological features of chronic lymphocytic inflammation and eosinophilic infiltrates, with HLA-B13 and DRB113 alleles indicating genetic susceptibility to hypersensitivity, while histological findings suggested a localized FDR-like reaction. Case II exhibited borderline α-Gal-specific IgE, resolving completely with a mammalian-free diet. The presence of HLA-DRB101 and DQB1*05 in the second patient indicated a genetic predisposition to AGS and other atopic conditions. No infectious etiology was identified in either case. These findings emphasize the heterogeneity of tick-related hypersensitivity and the importance of HLA genotypes in susceptibility. Comprehensive molecular, immunological, and genetic profiling offers valuable insights into the mechanisms of hypersensitivity, supporting personalized approaches for the diagnosis and management of tick-induced allergic conditions.

Rare causes of pediatric anaphylaxis due to obscure allergens

This review provides a comprehensive overview of rare causes of pediatric anaphylaxis related to obscure allergens. Anaphylaxis, a severe hypersensitivity reaction, can occur without typical symptoms, posing diagnostic challenges, especially in children. Idiopathic anaphylaxis, where no trigger is identified despite thorough evaluation, is notably challenging in this population. This review synthesizes current literature, highlighting obscure triggers such as food additives, spices like fenugreek, and cross-reactive allergens, including lupine and gelatin. These allergens are often overlooked and can lead to misdiagnosis of idiopathic cases. Understanding these uncommon triggers is crucial for clinicians to ensure accurate diagnosis and effective management of pediatric anaphylaxis, emphasizing the need for heightened clinical awareness and further research. This review raises awareness among health care providers about these lesser-known causes, aiming to improve outcomes and quality of life for pediatric patients at risk of anaphylactic reactions.

Pediatric idiopathic anaphylaxis: practical management from infants to adolescents

Idiopathic anaphylaxis (IA) remains a frustrating challenge for both patients and physicians. The aim of this paper is to focus on IA in pediatric ages and suggest possible diagnostic algorithms according to specific age ranges (infants, children, and adolescents). In fact, in a variable percentage of patients, despite extensive diagnostic tests, the cause of anaphylactic episodes cannot be identified. Moreover, the lack of a unanimous IA definition requires a careful and detailed diagnostic workup. Prompt recognition of signs and symptoms, especially in younger children, and an accurate clinical history often allow a choice of the most appropriate diagnostic tests and a correct differential diagnosis.

Allergic reactions to tick saliva components in zebrafish model

BACKGROUND

Alpha-Gal syndrome (AGS) is a tick-borne food allergy caused by IgE antibodies against the glycan galactose-alpha-1,3-galactose (α-Gal) present in glycoproteins and glycolipids from mammalian meat. To advance in the diagnosis and treatment of AGS, further research is needed to unravel the molecular and immune mechanisms underlying this syndrome. The objective of this study is the characterization of tick salivary components and proteins with and without α-Gal modifications involved in modulating human immune response against this carbohydrate.

METHODS

Protein and α-Gal content were determined in tick saliva components, and proteins were identified by proteomics analysis of tick saliva fractions. Pathophysiological changes were recorded in the zebrafish (Danio rerio) model after exposure to distinct Ixodes ricinus tick salivary components. Serum samples were collected from zebrafish at day 8 of exposure to determine anti-α-Gal, anti-glycan, and anti-tick saliva protein IgM antibody titers by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Zebrafish treated with tick saliva and saliva protein fractions combined with non-protein fractions demonstrated significantly higher incidence of hemorrhagic type allergic reactions, abnormal behavioral patterns, or mortality when compared to the phosphate-buffered saline (PBS)-treated control group. The main tick salivary proteins identified in these fractions with possible functional implication in AGS were the secreted protein B7P208-salivary antigen p23 and metalloproteases. Anti-α-Gal and anti-tick salivary gland IgM antibody titers were significantly higher in distinct saliva protein fractions and deglycosylated saliva group when compared with PBS-treated controls. Anti-glycan antibodies showed group-related profiles.

CONCLUSIONS

Results support the hypothesis that tick salivary biomolecules with and without α-Gal modifications are involved in modulating immune response against this carbohydrate.

Clinical Presentation of Alpha-Gal Syndrome in Pediatric Gastroenterology and Response to Mammalian Dietary Elimination

INTRODUCTION

Alpha-gal syndrome is an immunoglobulin E (IgE)-mediated delayed hypersensitivity reaction to nonprimate mammalian products, which has a newly established gastrointestinal (GI) phenotype in adults. We assessed the GI presentation and treatment response in children.

METHODS

This is a retrospective study of patients presenting in a pediatric gastroenterology clinic tested for alpha-gal IgE.

RESULTS

Forty of 199 patients (20%) tested had a positive alpha-gal-specific IgE, with 77.5% reporting GI symptoms in isolation. Of the 30 that attempted dietary elimination, 8 (27%) experienced full resolution of symptoms.

DISCUSSION

Alpha-gal syndrome can present with isolated GI symptoms in children.

Hidden and Rare Food Allergens in Pediatric Age

In food allergy management, the avoidance of the allergen that caused the reaction plays a fundamental role. Nevertheless, that can be thwarted in case of accidental exposure to a rare or hidden allergen, causing the adoption of a monotonous diet and a consequent reduction in the quality of life of the patient and their family. The identification of a rare and hidden allergen is an important diagnostic challenge, taking into account that a significant proportion of all food reactions is in reality due to them. The aim of the present review is to provide the pediatric allergist an overview of the possible sources of rare and hidden food allergens, taking into consideration the routes of exposure to these potential allergens with the main examples published in the scientific literature and the distinction between types of direct or cross-contamination. The identification of the allergen responsible for the reaction and the provision of a dietary advice customized for the specific individual's dietary habits is essential to improve quality of life of the familiar nucleus and to reduce the risk of further allergic reactions.

Allergies to food and airborne allergens in children and adolescents: role of epigenetics in a changing environment

Allergic diseases affect millions of children and adolescents worldwide. In this Review, we focus on allergies to food and airborne allergens and provide examples of prevalence trends during a time when climate change is of increasing concern. Profound environmental changes have affected natural systems in terms of biodiversity loss, air pollution, and climate. We discuss the potential links between these changes and allergic diseases in children, and the clinical implications. Several exposures of relevance for allergic disease also correlate with epigenetic changes such as DNA methylation. We propose that epigenetics could be a promising tool by which exposures and hazards related to a changing environment can be captured. Epigenetics might also provide promising biomarkers and help to elucidate the mechanisms related to allergic disease initiation and progress.

The impact of type 2 immunity and allergic diseases in atherosclerosis

Allergic diseases are allergen-induced immunological disorders characterized by the development of type 2 immunity and IgE responses. The prevalence of allergic diseases has been on the rise alike cardiovascular disease (CVD), which affects arteries of different organs such as the heart, the kidney and the brain. The underlying cause of CVD is often atherosclerosis, a disease distinguished by endothelial dysfunction, fibrofatty material accumulation in the intima of the artery wall, smooth muscle cell proliferation, and Th1 inflammation. The opposed T-cell identity of allergy and atherosclerosis implies an atheroprotective role for Th2 cells by counteracting Th1 responses. Yet, the clinical association between allergic disease and CVD argues against it. Within, we review different phases of allergic pathology, basic immunological mechanisms of atherosclerosis and the clinical association between allergic diseases (particularly asthma, atopic dermatitis, allergic rhinitis and food allergy) and CVD. Then, we discuss putative atherogenic mechanisms of type 2 immunity and allergic inflammation including acute allergic reactions (IgE, IgG1, mast cells, macrophages and allergic mediators such as vasoactive components, growth factors and those derived from the complement, contact and coagulation systems) and late phase inflammation (Th2 cells, eosinophils, type 2 innate-like lymphoid cells, alarmins, IL-4, IL-5, IL-9, IL-13 and IL-17).

Current and Future Strategies for the Diagnosis and Treatment of the Alpha-Gal Syndrome (AGS)

The α-Gal syndrome (AGS) is a pathognomonic immunoglobulin E (IgE)-mediated delayed anaphylaxis in foods containing the oligosaccharide galactose-α-1,3-galactose (α-Gal) such as mammalian meat or dairy products. Clinical presentation of AGS can also comprise immediate hypersensitivity due to anticancer therapy, gelatin-containing vaccines or mammalian serum-based antivenom. The IgE initial sensitization is caused by hard-bodied tick bites and symptomatic individuals typically develop delayed pruritus, urticaria, angioedema, anaphylaxis, malaise or gut-related symptoms. Due to inapparent presentation, delayed reactions and a wide variety of patients´ clinical history, the AGS diagnosis and treatment remain challenging. This review covers not only current diagnostic methods used for AGS such as the skin prick test (SPT), the oral food challenge (OFC), anti-α-Gal IgE levels measurement and the basophil activation test (BAT), but also potentially relevant next-generation diagnostic tools like the mast cell activation test (MAT), the histamine-release (HR) assay, omics technologies and model-based reasoning (MBR). Moreover, it focuses on the therapeutical medical and non-medical methods available and current research methods that are being applied in order to elucidate the molecular, physiological and immune mechanisms underlying this allergic disorder. Lastly, future treatment and preventive tools are also discussed, being of utmost importance for the identification of tick salivary molecules, with or without α-Gal modifications, that trigger IgE sensitivity as they could be the key for further vaccine development. Bearing in mind climate change, the tick-host paradigm will shift towards an increasing number of AGS cases in new regions worldwide, which will pose new challenges for clinicians in the future.