Lipid transfer protein allergy: A review of current controversies

The Diagnosis of Allergy to Lipid Transfer Proteins

PURPOSE OF REVIEW

To provide an update on the diagnosis of non-specific Lipid Transfer Protein (nsLTP) allergy.

RECENT FINDINGS

More publications report the presence of nsLTP allergy in Northern European countries and nsLTP sensitisation in children. Individuals are more likely to have severe reactions if there is recognition of increasing numbers of LTP components. Diagnosis is problematic; not all those with nsLTP allergy will have a positive test to a peach extract containing Pru p 3, the peach nsLTP. Sensitisation to nsLTP is being reported in more countries, including to the nsLTP in Cannabis Sativa in North America. Meals containing multiple nsLTP foods are more likely to be involved in co-factor reactions. Component-resolved diagnostics are superior to skin prick tests, to determine sensitisation to the individual nsLTP allergens causing symptoms and, in the future, the Basophil Activation test may best discriminate between sensitization and clinical allergy.

Clinical and serological characteristics of patients allergic to LTP

BACKGROUND

Allergy to lipid transfer proteins (LPT) is common in Mediterranean Europe, and it causes severe reactions in patients and affects multiple foods, impairing the quality of life.

OBJECTIVE

This study aimed to describe the clinical and sensitization profile of patients with LTP syndrome and to determine a clinical pattern of severity. Molecular diagnosis is shown in a broad population through microarrays.

MATERIAL AND METHODS

This study was performed at the LTP Allergy Consultation of the Reina Sofia Hospital in Murcia, Spain. We analyzed the patients' characteristics, reactions, cofactors, food implicated, quality of life, skin prick test to food and aeroallergens, and serologic parameters, such as total immunoglobulin E, peach LTP (Pru p 3 IgE) and immunoglobulin G4, and microarray Immuno Solid-phase Allergen Chip (ISAC). We related the severity of the reactions with other variables.

RESULTS

We presented a series of 236 patients diagnosed with LTP allergy, 54.66% suffering from anaphylaxis, 36.02% from urticaria angioedema, and 9.32% from oral allergy syndrome. The most frequently implicated food was peach, producing symptoms in 70% of patients, followed by walnut in 55%, peanut in 45%, hazelnut in 44%, and apple in 38% patients. Regarding the food that provoked anaphylaxis, walnut was the most frequent instigator, along with peach, peanut, hazelnut, almond, sunflower seed, and apple. According to the severity of LPT reaction, we did not discover significant differences in gender, age, food group involved, and serologic parameters. We found differences in the presence of cofactors, with 48.84% of cofactors in patients with anaphylaxis, compared to 27.1% in patients without anaphylaxis and in family allergy background (P < 0.0001).

CONCLUSION

In our series of patients, 54% presented anaphylaxis, and the foods that most frequently produced symptoms were peaches, apples, and nuts. Cofactors and family allergy backgrounds were associated with the severity of LPT reaction.

IgE-Mediated Allergy and Asymptomatic Sensitization to Cannabis Allergens-Review of Current Knowledge and Presentation of Six Cases

Cannabis allergy is a relatively new phenomenon described in the 1970s. Its increased frequency has been observed over the last years due to the increasing therapeutic and recreational use of cannabis-based products. Sensitization possibly leading to allergy symptoms can occur not only through the smoking of cannabis, but also through ingestion, the inhalation of pollen, or direct contact. The severity of symptoms varies from benign pruritus to anaphylaxis. There is scant information available to support clinicians throughout the entire therapeutic process, starting from diagnosis and ending in treatment. In this review, we present six cases of patients in whom molecular in vitro testing revealed sensitization to cannabis extract and/or cannabis-derived nsLTP molecules (Can s 3). Based on these cases, we raise important questions regarding this topic. The article discusses current proposals and highlights the importance of further research not only on cannabis allergy but also on asymptomatic sensitization to cannabis allergens, which may be ascertained in some percentage of the population.

Worldwide Heterogeneity of Food Allergy: Focus on Peach Allergy in Southern Italy

Food allergy (FA) has shown an increasing prevalence in the last decades, becoming a major public health problem. However, data on the prevalence of FA across the world are heterogeneous because they are influenced by several factors. Among IgE-mediated FA, an important role is played by FA related to plant-derived food which can result from the sensitization to a single protein (specific FA) or to homologous proteins present in different foods (cross-reactive FA) including non-specific lipid transfer proteins (nsLTPs), profilins, and pathogenesis-related class 10 (PR-10). In addition, the clinical presentation of FA is widely heterogeneous ranging from mild symptoms to severe reactions up to anaphylaxis, most frequently associated with nsLTP-related FA (LTP syndrome). Considering the potential life-threatening nature of nsLTP-related FA, the patient's geographical setting should always be taken into account; thereby, it is highly recommended to build a personalized approach for managing FA across the world in the precision medicine era. For this reason, in this review, we aim to provide an overview of the prevalence of nsLTP-mediated allergies in the Mediterranean area and to point out the potential reasons for the different geographical significance of LTP-driven allergies with a particular focus on the allergenic properties of food allergens and their cross reactivity.

Feast for thought: A comprehensive review of food allergy 2021-2023

A review of the latest publications in food allergy over the past couple of years confirmed that food allergy is a major public health concern, affecting about 8% of children and 10% of adults in developed countries. The prevalence of food allergy varies around the world, with the increase being driven mainly by environmental factors, possibly together with genetic susceptibility to environmental changes. A precise diagnosis of food allergy is extremely important. Both new tests (eg, the basophil activation test) and improved optimization of information provided by existing tests (eg, the skin prick test and measurement of specific IgE level) can contribute to improving the accuracy and patients' comfort of food allergy diagnosis. Understanding the underlying immune mechanisms is fundamental to designing allergen-specific treatments that can be safe and effective in the long term. New discoveries of the immune response to food allergens, including T-cell and B-cell responses, have emerged. Novel therapeutic approaches are being trialed at various stages of development as attempts to allow for more active intervention to treat food allergy. Prevention is key to reducing the increase in prevalence. Early introduction of allergenic foods seems to be the most effective intervention, but others are being studied, and will, it is hoped, lead to modification of the epidemiologic trajectory of food allergy over time.

Understanding of lipid transfer protein sensitization patterns and its clinical significance in children

Background: Lipid transfer proteins (LTP) are the most common food allergens in the Mediterranean region. Objective: The study aimed to investigate co-sensitization patterns and cluster relationships between LTP allergen molecules across a broad range of allergen-specific sensitization patterns, and clinical outcomes in eastern Mediterranean children. Methods: Among 496 children evaluated for multiple sensitizations with multiplex testing, 105 children (21%) with 16 different LTP sensitizations were analyzed. Clinical reactivity was examined based on clear-cut history of immunoglobulin E mediated symptoms (oral allergy syndrome [OAS], systemic reactions, and anaphylaxis). Results: All children included were sensitive to food LTPs, but 56% were sensitive to pollen LTPs. The number of children with OAS and clinical reactivity was 12 and 59, respectively, and no cofactors were reported. The most common sensitizations were Pru p 3 (74%) and Cor a 8 (66%). Significant correlations were observed in the heatmap between the LTP molecules other than Par j 2 and Tri a 14. Overall, clinical reactivity was associated with increased age and number of LTP molecule positivity. Conclusion: In the eastern Mediterranean region, 21% of children with multiple food and/or pollen sensitizations were found to have LTP sensitization; however, almost half reported clinical reactivity. The hierarchical pathway highlights that distinct LTP allergen molecules can act as primary sensitizers. Clinical reactivity is linked to increasing numbers of LTP molecule positivity and increasing age.

Factors and co-factors influencing clinical manifestations in nsLTPs allergy: between the good and the bad

Non-specific lipid transfer proteins (nsLTPs) are a family of plant pan-allergens that represent the primary cause of food allergies in the Mediterranean area, characterized by a wide range of clinical manifestations, ranging from the total absence of symptoms up to anaphylaxis. This wide variety of symptoms is related to the intrinsic capacity of nsLTPs to cause an allergic reaction in a specific subject, but also to the presence of co-factors exacerbating (i.e., exercise, NSAIDs, PPIs, alcohol, cannabis, prolonged fasting, menstruation, acute infections, sleep deprivation, chronic urticaria) or protecting from (i.e., co-sensitization to PR10, profilin or polcalcin) severe reactions. In this picture, recognizing some nsLTPs-related peculiarities (i.e., route, type and number of sensitizations, concentration of the allergen, cross-reactions) and eventual co-factors may help the allergist to define the risk profile of the single patient, in order to promote the appropriate management of the allergy from dietary advices up to the prescription of life-saving epinephrine autoinjector.

The future of food allergy: Challenging existing paradigms of clinical practice

The field of food allergy has seen tremendous change over the past 5-10 years with seminal studies redefining our approach to prevention and management and novel testing modalities in the horizon. Early introduction of allergenic foods is now recommended, challenging the previous paradigm of restrictive avoidance. The management of food allergy has shifted from a passive avoidance approach to active interventions that aim to provide protection from accidental exposures, decrease allergic reaction severity and improve the quality of life of food-allergic patients and their families. Additionally, novel diagnostic tools are making their way into clinical practice with the goal to reduce the need for food challenges and assist physicians in the-often complex-diagnostic process. With all the new developments and available choices for diagnosis, prevention and therapy, shared decision-making has become a key part of medical consultation, enabling patients to make the right choice for them, based on their values and preferences. Communication with patients has also become more complex over time, as patients are seeking advice online and through social media, but the information found online may be outdated, incorrect, or lacking in context. The role of the allergist has evolved to embrace all the above exciting developments and provide patients with the optimal care that fits their needs. In this review, we discuss recent developments as well as the evolution of the field of food allergy in the next decade.

Evaluation and Updated Classification of Acute Hypersensitivity Reactions to Nonsteroidal Anti-Inflammatory Drugs (NSAIDs): NSAID-Exacerbated or -Induced Food Allergy

BACKGROUND

There are hypersensitivity reactions (HRs) to foods in which nonsteroidal anti-inflammatory drugs (NSAIDs) act as aggravating factors (NSAID-exacerbated food allergy [NEFA]) or cofactors (NSAID-induced food allergy [NIFA]), often misdiagnosed as HRs to NSAIDs. Urticarial/angioedematous and/or anaphylactic reactions to two or more chemically unrelated NSAIDs do not meet current classification criteria. However, they may be considered part of a cross-reactive type of acute HR, which is NSAID-induced urticaria/angioedema with or without respiratory or systemic symptoms of anaphylaxis.

OBJECTIVE

To evaluate patients reporting acute HRs to NSAIDs and classify them according to updated criteria.

METHODS

We prospectively studied 414 patients with suspected HRs to NSAIDs. For all whom met these criteria, NEFA/NIFA was diagnosed: (1) mild reactions to (NEFA) or tolerance of (NIFA) the suspected foods without taking NSAIDs; (2) cutaneous and/or anaphylactic reactions to the combination foods plus NSAIDs; (3) positive allergy tests to the suspected foods; and (4) negative drug challenges (DCs) with the NSAIDs involved.

RESULTS

A total of 252 patients were given the diagnosis of NSAID hypersensitivity (60.9%), 108 of whom had NSAID-induced urticaria/angioedema with or without respiratory or systemic symptoms of anaphylaxis. We excluded NSAID hypersensitivity in 162 patients (39.1%) who tolerated DCs with the suspected NSAIDs, nine of whom received a diagnosis of NEFA, and 66 of NIFA. Pru p 3 was implicated in 67 of those 75 patients who received a diagnosis of NEFA or NIFA.

CONCLUSIONS

NEFA and NIFA account for about 18% of patients reporting HRs to NSAIDs, in which Pru p 3 is the main responsible food allergen. Therefore, patients with cutaneous and/or anaphylactic reactions to NSAIDs should be carefully questioned about all foods ingested within 4 hours before or after NSAID exposure, and targeted food allergy tests should be considered in the diagnostic workup of these patients. If testing is positive, DCs with the suspected NSAIDs should also be considered.

Immunotherapy with Pru p 3 for food allergy to peach and non-specific lipid transfer protein: a systematic review

BACKGROUND

Non-specific lipid-transfer protein (nsLTP) is a pan-allergen in the plant world, and a cause of significant concern as food allergen in the Mediterranean area, due to its general heat- and acid-resistance and hence the risk of severe allergic reactions. Pru p 3, the peach nsLTP, is considered the primary sensitizer to this allergen family and this allergy is usually persistent. Allergen-free diet and acute treatment of manifestations are the main recognized management goals in food allergy.

MAIN TEXT

The role of immunotherapy for treating food allergy in adult patients is controversial, but immunotherapy for Pru p 3 could potentially represent a relevant therapeutic strategy. We systematically searched databases for studies assessing the role of immunotherapy Pru p 3 in food allergy. Overall, nine studies were included. Immunotherapy with Pru p 3 appears to be effective and with a good safety profile in both peach and LTP allergy for some foods, such as peanut, in both RCT and real-life studies.

CONCLUSIONS

Immunotherapy with Pru p 3 is a possible treatment option for food allergy to the peach LTP in the Mediterranean area, although at present have not reached routinary clinical practice. Larger studies are needed to confirm these findings and identify predictive biomarkers.

Anaphylaxis across Europe: are pollen food syndrome and lipid transfer protein allergy so far apart?

PURPOSE OF REVIEW

Traditionally pollen-food syndrome (PFS) is considered to be a mild cross-reacting food allergy affecting only Northern Europe, with lipid transfer protein (LTP) allergy being more severe and mainly occurring in Southern Europe. This review seeks to update the reader on both types of plant food allergy and to determine whether the stereotypical presentations of these plant food allergies remain the same, with a particular focus on reaction severity.

RECENT FINDINGS

Recent findings suggest that both these types of plant food allergy occur in children and adults. Although it is true that PFS allergy is more prevalent in Northern Europe and LTP allergy is more well known in Southern Europe, these conditions are not hidebound by geography, and the increasing spread and allergenicity of pollen due to global warming continues to change their presentation. Both conditions have a spectrum of symptom severity, with PFS sometimes presenting with more severe symptoms, including anaphylaxis and LTP allergy with milder reactions.

SUMMARY

It is important to consider that in many parts of Europe, reactions to plant foods, especially fruits or vegetables, could be mediated either by pollen cross-reactivity or primary sensitization to LTP allergens. All those presenting with symptoms to plant foods will benefit from a detailed clinical history and appropriate tests so that an accurate diagnosis can be made, and correct management implemented.

Epinephrine Auto-Injector Prescription and Use: A Retrospective Analysis and Clinical Risk Assessment of Adult Patients Sensitized to Lipid Transfer Protein

Lipid transfer proteins (LTPs) are widely widespread plant food allergens which represents the main cause of food allergy in adults living in the Mediterranean basin. The purpose of this study was to investigate in LTP patients the actual use of prescribed epinephrine auto-injector and appropriateness of its prescription. In addition, we investigated in these patients: (1) occurrence of new food reaction in the following three years after to diagnosis; (2) need and number of access to emergency services; (3) presence of possible predictive factors to further food reactions. One-hundred sixty-five adult patients sensitized to LTPs have been included. During follow-up, we recorded 68 further reactions, most of them (77.9%) characterized by local symptoms; rarely the patients required an emergency-department visits (16.1%) and only one patient (1.7%) used the epinephrine auto-injector. The patients with a previous history of anaphylaxis at baseline turned back to access to emergency services also during the follow-up (p = 0.006). The majority of patients with recorded systemic reactions (p = 0.004) and treated in an emergency room (p = 0.028) did not have any co-factor-enhanced at diagnosis. We noted an association between platanus pollen sensitization and severity of further reactions during the follow-up (p = 0.026). Epinephrine auto-injector were prescribed to 108/165 patients (65.5%) with an over-prescription rate of 25%. The unforeseeable clinical presentation of LTP allergic reactions and the eventual role played by the cofactor make necessary schedule a follow-up to monitor the patients over time and to assess the actual use of epinephrine auto injectors prescribed.

Peanut allergy in Italy: A unique Italian perspective

Background

Peanut allergy has not been well characterized in Italy.

Objective

Our aim was to better define the clinical features of peanut allergy in Italy and to detect the peanut proteins involved in allergic reactions.

Methods

A total of 22 centers participated in a prospective survey of peanut allergy over a 6-month period. Clinical histories were confirmed by in vivo and/or in vitro diagnostic means in all cases. Potential risk factors for peanut allergy occurrence were considered. Levels of IgE to Arachis hypogea (Ara h) 1, 2, 3, 6, 8, and 9 and profilin were measured.

Results

A total of 395 patients (aged 2-80 years) were enrolled. Of the participants, 35% reported local reactions, 38.2% reported systemic reactions, and 26.6% experienced anaphylaxis. The sensitization profile was dominated by Ara h 9 (77% of patients were sensitized to it), whereas 35% were sensitized to pathogenesis-related protein 10 (PR-10) and 26% were sensitized to seed storage proteins (SSPs). Sensitization to 2S albumins (Ara h 2 and Ara h 6) or lipid transfer protein (LTP) was associated with the occurrence of more severe symptoms, whereas profilin and PR-10 sensitization were associated with milder symptoms. Cosensitization to profilin reduced the risk of severe reactions in both Ara h 2- and LTP-sensitized patients. SSP sensitization prevailed in younger patients whereas LTP prevailed in older patients (P < .01). SSP sensitization occurred mainly in northern Italy, whereas LTP sensitization prevailed in Italy's center and south. Atopic dermatitis, frequency of peanut ingestion, peanut consumption by other family members, or use of peanut butter did not seem to be risk factors for peanut allergy onset.

Conclusions

In Italy, peanut allergy is rare and dominated by LTP in the country's center and south and by SSP in the north. These 2 sensitizations seem mutually exclusive. The picture differs from that in Anglo-Saxon countries.

Rosaceae food allergy: a review

This review provides a global overview on Rosaceae allergy and details the particularities of each fruit allergy induced by ten Rosaceae species: almond/peach/cherry/apricot/plum (Amygdaleae), apple/pear (Maleae), and raspberry/blackberry/strawberry (Rosoideae). Data on clinical symptoms, prevalence, diagnosis, and immunotherapies for the treatment of Rosaceae allergy are herein stated. Allergen molecular characterization, cross-reactivity/co-sensitization phenomena, the impact of food processing and digestibility, and the methods currently available for the Rosaceae detection/quantification in foods are also described. Rosaceae allergy has a major impact in context to pollen-food allergy syndrome (PFAS) and lipid transfer protein (LTP) allergies, being greatly influenced by geography, environment, and presence of cofactors. Peach, apple, and almond allergies are probably the ones most affecting the quality of life of the allergic-patients, although allergies to other Rosaceae fruits cannot be overlooked. From patients' perspective, self-allergy management and an efficient avoidance of multiple fruits are often difficult to achieve, which might raise the risk for cross-reactivity and co-sensitization phenomena and increase the severity of the induced allergic responses with time. At this point, the absence of effective allergy diagnosis (lack of specific molecular markers) and studies advancing potential immunotherapies are some gaps that certainly will prompt the progress on novel strategies to manage Rosaceae food allergies.