IgE, α-Gal and atherosclerosis

Zebrafish gut microbiota composition in response to tick saliva biomolecules correlates with allergic reactions to mammalian meat consumption

The α-Gal syndrome (AGS) is an IgE-mediated tick borne-allergy that results in delayed anaphylaxis to the consumption of mammalian meat and products containing α-Gal. Considering that α-Gal-containing microbiota modulates natural antibody production to this glycan, this study aimed to evaluate the influence on tick salivary compounds on the gut microbiota composition in the zebrafish (Danio rerio) animal model. Sequencing of 16 S rDNA was performed in a total of 75 zebrafish intestine samples, representing different treatment groups: PBS control, Ixodes ricinus tick saliva, tick saliva non-protein fraction (NPF), tick saliva protein fraction (PF), and tick saliva protein fractions 1-5 with NPF (F1-5). The results revealed that treatment with tick saliva and different tick salivary fractions, combined with α-Gal-positive dog food feeding, resulted in specific variations in zebrafish gut microbiota composition at various taxonomic levels and affected commensal microbial alpha and beta diversities. Metagenomics results were corroborated by qPCR, supporting the overrepresentation of phylum Firmicutes in the tick saliva group, phylum Fusobacteriota in group F1, and phylum Cyanobacteria in F2 and F5 compared to the PBS-control. qPCRs results at genus level sustained significant enrichment of Plesiomonas spp. in groups F3 and F5, Rhizobium spp. in NPF and F4, and Cloacibacterium spp. dominance in the PBS control group. This study provides new results on the role of gut microbiota in allergic reactions to tick saliva components using a zebrafish model of AGS. Overall, gut microbiota composition in response to tick saliva biomolecules may be associated with allergic reactions to mammalian meat consumption in AGS.

Tick bites, IgE to galactose-alpha-1,3-galactose and urticarial or anaphylactic reactions to mammalian meat: The alpha-gal syndrome

The recent recognition of a syndrome of tick-acquired mammalian meat allergy has transformed the previously held view that mammalian meat is an uncommon allergen. The syndrome, mediated by IgE antibodies against the oligosaccharide galactose-alpha-1,3-galactose (alpha-gal), can also involve reactions to visceral organs, dairy, gelatin and other products, including medications sourced from non-primate mammals. Thus, fittingly, this allergic disorder is now called the alpha-gal syndrome (AGS). The syndrome is strikingly regional, reflecting the important role of tick bites in sensitization, and is more common in demographic groups at risk of tick exposure. Reactions in AGS are delayed, often by 2-6 h after ingestion of mammalian meat. In addition to classic allergic symptomatology such as urticaria and anaphylaxis, AGS is increasingly recognized as a cause of isolated gastrointestinal morbidity and alpha-gal sensitization has also been linked with cardiovascular disease. The unusual link with tick bites may be explained by the fact that allergic cells and mediators are mobilized to the site of tick bites and play a role in resistance against ticks and tick-borne infections. IgE directed to alpha-gal is likely an incidental consequence of what is otherwise an adaptive immune strategy for host defense against endo- and ectoparasites, including ticks.

IgE to common food allergens is associated with cardiovascular mortality in the National Health and Examination Survey and the Multi-Ethnic Study of Atherosclerosis

BACKGROUND

In individuals without symptomatic food allergy, food-specific IgE is considered clinically irrelevant. However, recent studies have suggested that galactose-α-1,3-galactose (alpha-gal) IgE is associated with cardiovascular (CV) disease.

OBJECTIVE

We sought to determine whether sensitization to common food allergens is associated with CV mortality.

METHODS

The association between IgE sensitization to foods and CV mortality ascertained to 2019 was examined in the National Health and Examination Survey (NHANES) 2005-2006 and the Wake Forest site of the Multi-Ethnic Study of Atherosclerosis (MESA) cohort; MESA enrolled adults without baseline clinical CV diseases between 2000 and 2002. Total and specific IgE was measured to cow's milk, egg, peanut, shrimp, and a panel of aeroallergens (NHANES), and to cow's milk, alpha-gal, peanut, dust mite, and timothy grass (MESA). Cox proportional hazard models were constructed, adjusting for sex, age, race/ethnicity, smoking, education, and asthma.

RESULTS

A total of 4414 adults from NHANES (229 CV deaths) and 960 from MESA (56 CV deaths) were included. In NHANES, sensitization to at least 1 food was associated with higher CV mortality (hazard ratio [HR], 1.7 [95% confidence interval (CI), 1.2-2.4], P = .005). Milk sensitization was particularly associated (HR, 2.0 [95% CI, 1.1-3.8], P = .026), a finding replicated in MESA (HR, 3.8 [95% CI, 1.6-9.1], P = .003). Restricting analyses in NHANES to consumers of the relevant allergen strengthened food sensitization relationships, unmasking shrimp and peanut sensitization as additional risk factors for CV mortality.

CONCLUSIONS

The finding that food sensitization is associated with increased risk of CV mortality challenges the current paradigm that sensitization without overt allergy is benign. Further research is needed to clarify mechanisms of this association.

The α-Gal epitope - the cause of a global allergic disease

The galactose-α-1,3-galactose (α-Gal) epitope is the cause of a global allergic disease, the α-Gal syndrome (AGS). It is a severe form of allergy to food and products of mammalian origin where IgE against the mammalian carbohydrate, α-Gal, is the cause of the allergic reactions. Allergic reactions triggered by parenterally administered α-Gal sources appear immediately, but those triggered via the oral route appear with a latency of several hours. The α-Gal epitope is highly immunogenic to humans, apes and old-world monkeys, all of which produce anti-α-Gal antibodies of the IgM, IgA and IgG subclasses. Strong evidence suggests that in susceptible individuals, class switch to IgE occurs after several tick bites. In this review, we discuss the strong immunogenic role of the α-Gal epitope and its structural resemblance to the blood type B antigen. We emphasize the broad abundance of α-Gal in different foods and pharmaceuticals and the allergenicity of various α-Gal containing molecules. We give an overview of the association of tick bites with the development of AGS and describe innate and adaptive immune response to tick saliva that possibly leads to sensitization to α-Gal. We further discuss a currently favored hypothesis explaining the mechanisms of the delayed effector phase of the allergic reaction to α-Gal. We highlight AGS from a clinical point of view. We review the different clinical manifestations of the disease and the prevalence of sensitization to α-Gal and AGS. The usefulness of various diagnostic tests is discussed. Finally, we provide different aspects of the management of AGS. With climate change and global warming, the tick density is increasing, and their geographic range is expanding. Thus, more people will be affected by AGS which requires more knowledge of the disease.

Multi-omics analysis of zebrafish response to tick saliva reveals biological processes associated with alpha-Gal syndrome

The alpha-Gal syndrome (AGS) is a tick-borne allergy. A multi-omics approach was used to determine the effect of tick saliva and mammalian meat consumption on zebrafish gut transcriptome and proteome. Bioinformatics analysis using R software was focused on significant biological and metabolic pathway changes associated with AGS. Ortholog mapping identified highly concordant human ortholog genes for the detection of disease-enriched pathways. Tick saliva treatment increased zebrafish mortality, incidence of hemorrhagic type allergic reactions and changes in behavior and feeding patterns. Transcriptomics analysis showed downregulation of biological and metabolic pathways correlated with anti-alpha-Gal IgE and allergic reactions to tick saliva affecting blood circulation, cardiac and vascular smooth muscle contraction, behavior and sensory perception. Disease enrichment analysis revealed downregulated orthologous genes associated with human disorders affecting nervous, musculoskeletal, and cardiovascular systems. Proteomics analysis revealed suppression of pathways associated with immune system production of reactive oxygen species and cardiac muscle contraction. Underrepresented proteins were mainly linked to nervous and metabolic human disorders. Multi-omics data revealed inhibition of pathways associated with adrenergic signaling in cardiomyocytes, and heart and muscle contraction. Results identify tick saliva-related biological pathways supporting multisystemic organ involvement and linking α-Gal sensitization with other illnesses for the identification of potential disease biomarkers.

Tick salivary glycans - a sugar-coated tick bite

Ticks are hematophagous arthropods that transmit disease-causing pathogens worldwide. Tick saliva deposited into the tick-bite site is composed of an array of immunomodulatory proteins that ensure successful feeding and pathogen transmission. These salivary proteins are often glycosylated, and glycosylation is potentially critical for the function of these proteins. Some salivary glycans are linked to the phenomenon of red meat allergy - an allergic response to red meat consumption in humans exposed to certain tick species. Tick salivary glycans are also invoked in the phenomenon of acquired tick resistance wherein non-natural host species exposed to tick bites develop an immune response that thwarts subsequent tick feeding. This review dwells on our current knowledge of these two phenomena, thematically linked by salivary glycans.

Food Allergies and Alpha-gal Syndrome for the Gastroenterologist

PURPOSE OF REVIEW

Food allergies are typically not considered as a cause of gastrointestinal (GI) distress without additional allergic symptoms, apart from celiac disease and eosinophilic esophagitis. However, recent reports of patients with alpha-gal syndrome who presented with GI-only symptoms like abdominal pain, vomiting, and diarrhea challenge this paradigm. Alpha-gal syndrome is an IgE-mediated allergy characterized by delayed reactions after eating mammalian meat or mammalian-derived products that contain galactose-alpha-1,3-galactose (alpha-gal). The purpose of this review is to discuss our current understanding of food allergies, GI illness, and the GI manifestations of alpha-gal syndrome.

RECENT FINDINGS

Among Southeastern U.S. GI clinic patients who screened positive for serum alpha-gal IgE, a majority of patients reported significant symptom improvement on an alpha-gal-avoidant diet, suggesting that the allergy had played a role in their GI symptoms. Diagnosis of alpha-gal syndrome is typically made with concerning allergic symptoms, elevated alpha-gal specific IgE in the serum, and symptom improvement on an alpha-gal avoidant diet. Alpha-gal syndrome can cause a delayed allergic response that is increasingly recognized worldwide, including among patients with predominant GI symptoms.

The Meat of the Matter: Understanding and Managing Alpha-Gal Syndrome

Alpha-gal syndrome is an unconventional food allergy, characterized by IgE-mediated hypersensitivity responses to the glycan galactose-alpha-1,3-galactose (alpha-gal) and not to a food-protein. In this review, we discuss how alpha-gal syndrome reframes our current conception of the mechanisms of pathogenesis of food allergy. The development of alpha-gal IgE is associated with tick bites though the possibility of other parasites promoting sensitization to alpha-gal remains. We review the immune cell populations involved in the sensitization and effector phases of alpha-gal syndrome and describe the current understanding of why allergic responses to ingested alpha-gal can be delayed by several hours. We review the foundation of management in alpha-gal syndrome, namely avoidance, but also discuss the use of antihistamines, mast cell stabilizers, and the emerging role of complementary and alternative therapies, biological products, and oral immunotherapy in the management of this condition. Alpha-gal syndrome influences the safety and tolerability of medications and medical devices containing or derived from mammalian products and impacts quality of life well beyond food choices.

Meat Allergy: A Ticking Time Bomb

Food allergies are relatively prevalent, but mammalian meat allergy remains uncommon and represents an important, potentially acute healthcare risk. This risk is partly because both clinicians and the public lack awareness of this serious allergy, which is unique in three important ways: it incurs a delayed reaction, it is induced by a carbohydrate rather than a protein, and it is linked to tick bites. Although various symptoms are possible, its unique presentation means that mammalian meat allergy is often presented to the dermatologist. We review this challenging subject, which is particularly salient considering the unique connection between ticks and mammalian meat allergy, the expanding tick territory, and the dependency by so many on meat products, not only in the diet but also in medications and medical devices.

Clinical Issues-April 2022

Perioperative care of the patient with alpha-gal syndrome Key words: alpha-gal syndrome (AGS), red meat allergy, allergic reaction, mammalian-derived ingredients, gelatin. Overnight storage of sterile supplies Key words: sterile supplies, event-related sterility, terminal cleaning, damp dusting, instrument table. Unsterile medication cartridges Key words: dental cartridge, local anesthesia, lidocaine, alcohol, sterile field. Personnel traffic into the OR Key words: OR traffic, door openings, airflow, environmental contamination, automatic doors.

Metabolism and Health Impacts of Dietary Sugars

Consumption of excessive amounts of added sugars and their effects on human health has been a major concern in the last several decades. Epidemiological data suggest that the incidence of metabolic disorders, such as obesity, nonalcoholic fatty liver disease, cardiovascular disease and diabetes, has increased due to chronic surplus consumption of these sugars. While many of these sugars have been isolated and studied for centuries, their health impacts and exact underlying mechanisms are still unclear. In this review, we discuss the pathophysiological role of 6 major simple sugars present in the human diet and the biochemical and molecular pathways related to their metabolism by different organs and gut microbiota, with a focus on the most recent investigations.

Tick Saliva and the Alpha-Gal Syndrome: Finding a Needle in a Haystack

Ticks and tick-borne diseases are significant public health concerns. Bioactive molecules in tick saliva facilitate prolonged blood-feeding and transmission of tick-borne pathogens to the vertebrate host. Alpha-gal syndrome (AGS), a newly reported food allergy, is believed to be induced by saliva proteins decorated with a sugar molecule, the oligosaccharide galactose-⍺-1,3-galactose (α-gal). This syndrome is characterized by an IgE antibody-directed hypersensitivity against α-gal. The α-gal antigen was discovered in the salivary glands and saliva of various tick species including, the Lone Star tick (Amblyomma americanum). The underlying immune mechanisms linking tick bites with α-gal-specific IgE production are poorly understood and are crucial to identify and establish novel treatments for this disease. This article reviews the current understanding of AGS and its involvement with tick species.

The roles of immune cells in atherosclerotic calcification

Atherosclerosis is the leading cause of acute cardiovascular events, and vascular calcification is an important pathological phenomenon in atherosclerosis. Recently, many studies have shown that immune cells are closely associated with the development of atherosclerosis and calcification, but there are many conflicting viewpoints because of immune system complications, such as the pro-atherosclerotic and atheroprotective effects of regulatory B cells (Bregs), T helper type 2 (Th2) cells and T helper type 17 (Th17) cells. In this review, we summarize the studies on the roles of immune cells, especially lymphocytes and macrophages, in atherosclerotic calcification. Furthermore, we prepared graphs showing the relationship between T cells, B cells and macrophages and atherosclerotic calcification. Finally, we highlight some potential issues that are closely associated with the function of immune cells in atherosclerotic calcification. Based on current research results, this review summarizes the relationship between immune cells and atherosclerotic calcification, and it will be beneficial to understand the relationship of immune cells and atherosclerotic calcification.

The Role of Food Allergy in Eosinophilic Esophagitis

Food allergy is often understood as an IgE-mediated hypersensitivity, characterized by allergic symptoms which occur “immediately” after the ingestion of a relevant food allergen. Increasingly, however, other food-related immune-mediated disorders are recognized in which symptoms can have a delayed onset and IgE does not play a central role. One of the described examples of the latter is eosinophilic esophagitis (EoE) – a disease defined pathologically by local eosinophilic inflammation in the esophagus in the setting of symptoms of esophageal dysfunction. The evidence that EoE is a food-mediated allergic disease includes i) almost all patients respond to an elemental diet and many respond to a diet in which dairy, wheat, eggs and/or soy are eliminated, ii) the presence of food-specific IgE and Th2 cells are consistent with a loss of tolerance to trigger foods and iii) many EoE patients have concomitant IgE-mediated food allergy and other allergic co-morbidities. This narrative review focuses on the hypothesis that EoE is a form of chronic food allergy. The goal is to describe similarities and differences in EoE and IgE-mediated food allergy, and to consider ways that these two increasingly common forms of food allergy are related to each other.

'Doc, will I ever eat steak again?': diagnosis and management of alpha-gal syndrome

PURPOSE OF REVIEW

Alpha-gal syndrome encompasses a constellation of symptoms associated with immune-mediated hypersensitivity responses to galactose-alpha-1,3-galactose (alpha-gal). The purpose of this review is to discuss our current understanding of the etiology, clinical symptoms, natural history, epidemiology, and management of alpha-gal syndrome.

RECENT FINDINGS

Sensitization to alpha-gal is associated with bites from ectoparasites like the lone star tick Amblyomma americanum. Allergic reactions in alpha-gal syndrome are often delayed and inconsistent. The magnitude of the allergic response depends on co-factors like exercise and alcohol consumption and the amount of alpha-gal and fat present in the food. Assaying alpha-gal-specific IgE in the serum is the primary diagnostic test used to confirm the allergy. Long-term management of the condition involves avoidance of both mammalian food products and tick bites.

SUMMARY

Alpha-gal syndrome disrupts the current paradigm for understanding food allergy. Exposure to an ectoparasite is critical for the development of specific IgE antibodies underlying sensitization, and allergic reactions depend on the activation of mast cells and basophils sensitized with IgE against a carbohydrate rather than a protein. Research in this field may lead to the development of improved diagnostic and therapeutic tools that can revolutionize the management of patients with alpha-gal syndrome.

A dataset for the analysis of antibody response to glycan alpha-Gal in individuals with immune-mediated disorders

Humans evolved by losing the capacity to synthesize the glycan Galα1-3Galβ1-(3)4GlcNAc-R (α-Gal), which resulted in the development of a protective response mediated by anti-α-Gal IgM/IgG/IgA antibodies against pathogens containing this modification on membrane proteins. As an evolutionary trade-off, humans can develop the alpha-Gal syndrome (AGS), a recently diagnosed disease mediated by anti-α-Gal IgE antibodies and associated with allergic reactions to mammalian meat consumption and tick bites. However, the anti-α-Gal antibody response may be associated with other immune-mediated disorders such as those occurring in patients with COVID-19 and Guillain-Barré syndrome (GBS). Here, we provide a dataset (209 entries) on the IgE/IgM/IgG/IgA anti-α-Gal antibody response in healthy individuals and patients diagnosed with AGS, tick-borne allergies, GBS and COVID-19. The data allows correlative analyses of the anti-α-Gal antibody response with factors such as patient and clinical characteristics, record of tick bites, blood group, age and sex. These analyses could provide insights into the role of anti-α-Gal antibody response in disease symptomatology and possible protective mechanisms.

A dataset for the analysis of antibody response to glycan alpha-Gal in individuals with immune-mediated disorders

Humans evolved by losing the capacity to synthesize the glycan Galα1-3Galβ1-(3)4GlcNAc-R (α-Gal), which resulted in the development of a protective response mediated by anti-α-Gal IgM/IgG/IgA antibodies against pathogens containing this modification on membrane proteins. As an evolutionary trade-off, humans can develop the alpha-Gal syndrome (AGS), a recently diagnosed disease mediated by anti-α-Gal IgE antibodies and associated with allergic reactions to mammalian meat consumption and tick bites. However, the anti-α-Gal antibody response may be associated with other immune-mediated disorders such as those occurring in patients with COVID-19 and Guillain-Barré syndrome (GBS). Here, we provide a dataset (209 entries) on the IgE/IgM/IgG/IgA anti-α-Gal antibody response in healthy individuals and patients diagnosed with AGS, tick-borne allergies, GBS and COVID-19. The data allows correlative analyses of the anti-α-Gal antibody response with factors such as patient and clinical characteristics, record of tick bites, blood group, age and sex. These analyses could provide insights into the role of anti-α-Gal antibody response in disease symptomatology and possible protective mechanisms.

On the cause and consequences of IgE to galactose-α-1,3-galactose: A report from the National Institute of Allergy and Infectious Diseases Workshop on Understanding IgE-Mediated Mammalian Meat Allergy

The mammalian meat allergy known as the "α-Gal syndrome" relates to IgE specific for galactose-α-1,3-galactose (α-Gal), an oligosaccharide that is present in cells and tissues of nonprimate mammals. The recognition of delayed reactions to food derived from mammals in patients with IgE to α-Gal and also the association with tick bites have been increasing worldwide. In 2018, the National Institute of Allergy and Infectious Diseases, Division of Allergy, Immunology and Transplantation, sponsored a workshop on this emerging tick-related disease. International experts from the fields of tick biology, allergy, immunology, infectious disease, and dermatology discussed the current state of our understanding of this emerging medical condition. The participants provided suggestions for specific research priorities and for the development of resources to advance our knowledge of the mechanisms, diagnosis, management, and prevention of this allergic disease. This publication is a summary of the workshop and the panel's recommendations are presented herein.

Diagnosis and Management of Patients with the α-Gal Syndrome

The galactose-α-1,3-galactose (α-Gal) syndrome has many novel features that are relevant to diagnosis and management. In most cases, the diagnosis can be made on a history of delayed allergic reactions to mammalian meat and the blood test for IgE to the oligosaccharide α-Gal. In general, the diagnosis also dictates the primary treatment, that is, avoiding mammalian meat and also dairy in some cases. In the United States, the lone star tick is the primary cause of this disease, but different ticks are responsible in other countries. Blood levels of IgE to α-Gal often drop in patients who avoid recurrent tick bites, but the rate of decline is variable. Similarly, the delay before reactions is variable and the severity of the allergic reactions is not predicted by the delay or the titer of specific IgE. Some mammalian-derived products such as heart valves, gelatin-based plasma expanders, and pancreatic enzymes are relevant to only select patient groups. A minority of cases may benefit from avoiding a wide range of products that are prepared with mammalian-derived constituents, such as gelatin. This review focuses on the nature of the syndrome, common challenges in diagnosis and management, and also gaps in our current knowledge that would benefit from additional investigation.