Expression, purification, characterization, and patient IgE reactivity of new macadamia nut iso-allergen.
Structural and functional information about food allergens is essential for understanding the allergenicity of food proteins. All allergens belong to a small number of protein families. Various allergens from different families have been successfully produced recombinantly in E. coli for their characterization and applications in allergy diagnosis and treatment. However, recombinant hexameric 11S seed storage protein has not been reported, although numerous 11S legumins are known to be food allergens, including the recently identified macadamia nut allergen Mac i 2. Here we report the production of a macadamia nut legumin by expressing it in E. coli with a substrate site of HRV 3C protease and cleaving the purified protein with HRV 3C protease. The protease divided the protein into two chains and left a native terminus for the C-terminal chain, resulting in a recombinant hexameric 11S allergen for the first time after the residues upstream to the cleavage site flipped out of the way of the trimer-trimer interaction. The 11S allergens are known to have multiple isoforms in many species. The present study removed an obstacle in obtaining homogeneous allergens needed for studying allergens and mitigating allergenicity. Immunoreactivity of the protein with serum IgE confirmed it to be a new isoform of Mac i 2. https://doi.org/10.1016/j.pep.2022.106211
Non-thermal processing of cashews: irradiation reduces allergenicity by altering the structure of Ana o 3.
Traditional thermal processing of cashews not only results in nutrient loss and harmful by-products, but also does not significantly reduce allergenicity. Irradiation could be an important non-thermal processing method to reduce cashew allergens' allergenicity and retain their nutritional properties. This study aimed to evaluate the effects of gamma irradiation processing on the structure and potential allergenicity of Ana o 3. The Ana o 3 solutions were gamma-irradiated at 0, 1, 3, 5, and 10 kGy. The structure change was monitored by Tricine-SDS-PAGE, circular dichroism spectroscopy, and fluorescence spectroscopy. The potential allergenicity was tested by immunoblotting, indirect competitive ELISA, and the human basophil KU812 degranulation assay using serum from cashew allergy patients. The results of CD spectroscopy showed that the content of α-helices decreased from 46.8% to 30.9% after 3 to 10 kGy, while the content of random coils increased from 23.7% to 33.3%. Meanwhile, a large number of hydrophobic regions were exposed, resulting in an increase in the hydrophobic surface of the protein. In terms of allergenicity, the IC50 values obtained by the competitive inhibition ELISA after irradiation increased from 0.628 to 4.054 μg mL-1, indicating that irradiation reduced the IgE binding capacity of Ana o 3, which was consistent with the results of western blotting. In addition, the basophil degranulation analysis showed that the release of IL-6, TNF-α, and histamine was decreased. It was shown that the potential allergenicity of the irradiated Ana o 3 was remarkably decreased since irradiation could mask or destroy the allergen epitopes, providing a new approach to reduce the allergenicity of cashew products. https://doi.org/10.1039/d2fo03057h
Structure and IgE Cross-Reactivity among Cashew, Pistachio, Walnut, and Peanut Vicilin-Buried Peptides.
Peanut and tree-nut allergies are frequently comorbid for reasons not completely understood. Vicilin-buried peptides (VBPs) are an emerging family of food allergens whose conserved structural fold could mediate peanut/tree-nut co-allergy. Peptide microarrays were used to identify immunoglobulin E (IgE) epitopes from the N-terminus of the vicilin allergens Ara h 1, Ana o 1, Jug r 2, and Pis v 3 using serum from three patient diagnosis groups: monoallergic to either peanuts or cashew/pistachio, or dual allergic. IgE binding peptides were highly prevalent in the VBP domains AH1.1, AO1.1, JR2.1, and PV3.1, but not in AO1.2, JR2.2, JR2.3, and PV3.2 nor the unstructured regions. The IgE profiles did not correlate with diagnosis group. The structure of the VBPs from cashew and pistachio was solved using solution-NMR. Comparisons of structural features suggest that the VBP scaffold from peanuts and tree-nuts can support cross-reactivity. This may help understand comorbidity and cross-reactivity despite a distant evolutionary origin. https://doi.org/10.1021/acs.jafc.2c07061
Real-World Safety Analysis of Preschool Tree Nut Oral Immunotherapy.
Background: Our group previously described preschool peanut oral immunotherapy (P-OIT) in a real-world multi-center setting, suggesting this therapy is safe for the vast majority of preschoolers. Objectives: We examined the safety and tolerability of tree nut (TN)-OIT in preschoolers in the real-world. Methods: As part of a Canada-wide quality improvement project, TN-OIT (cashew/pistachio, walnut/pecan, hazelnut, almond, macadamia nut) was administered to preschool-aged children who had (1) skin prick test ≥ 3mm or specific IgE level ≥ 0.35kU/L and convincing objective IgE-mediated reaction or (2) no ingestion history and specific IgE level ≥ 5kU/L. Patients built-up every two to four weeks to a maintenance dose of 300mg TN protein. Symptoms were recorded and classified using a modified World Allergy Organization Subcutaneous Immunotherapy Reaction Grading System (1 mildest, 5 fatal). Results: Of 92 patients who started TN-OIT from 2018-2021, 79 (85.9%) underwent single-food TN-OIT and 13 (14.1%) underwent multi-food TN-OIT to two (10.8%) or three (3.3%) TNs. Eighty-nine (96.7%) patients reached maintenance, and 4 dropped out (4.3%). Sixty-five (70.7%) patients experienced reactions during build-up: 35 (38.0%) grade 1, 30 (32.6%) grade 2 reactions, no grade 3 or 4 reactions, and 2 (2.17%) received epinephrine. Conclusions: Preschool TN-OIT in a real-world, multicenter setting appears safe and tolerable, with results comparable to our previously reported P-OIT findings. https://doi.org/10.1016/j.jaip.2023.01.031
Incorporating genetics in identifying peanut allergy risk and tailoring allergen immunotherapy: A perspective on the genetic findings from the LEAP trial.
Examining the genetics of peanut allergy (PA) in the context of clinical trial interventions and outcomes provides an opportunity to not only understand gene-environment interactions for PA risk but to also understand the benefit of allergen immunotherapy. A consistent theme in the genetics of food allergy is that in keeping with the dual allergen exposure hypothesis, barrier- and immune-related genes are most commonly implicated in food allergy and tolerance. With a focus on PA, we review how genetic risk factors across 3 genes (FLG, MALT1, and HLA-DQA1) have helped delineate distinct allergic characteristics and outcomes in the context of environmental interventions in the Learning Early about Peanut Allergy (LEAP) study and other clinical trials. We specifically consider and present a framework for genetic risk prediction for the development of PA and discuss how genetics, age, and oral consumption intertwine to predict PA outcome. Although there is some promise in this proposed framework, a better understanding of the mechanistic pathways by which PA develops and persists is needed to develop targeted therapeutics for established disease. Only by understanding the mechanisms by which PA develops, persists, and resolves can we identify adjuvants to oral immunotherapy to make older children and adults immunologically similar to their younger, more malleable counterparts and thus more likely to achieve long-term tolerance. https://doi.org/10.1016/j.jaci.2022.12.819
Effects of Nut Consumption on Blood Lipids and Lipoproteins: A Comprehensive Literature Update.
In the present review, we provide a comprehensive narrative overview of the current knowledge on the effects of total and specific types of nut consumption (excluding nut oil) on blood lipids and lipoproteins. We identified a total of 19 systematic reviews and meta-analyses of randomized controlled trials (RCTs) that were available in PubMed from the inception date to November 2022. A consistent beneficial effect of most nuts, namely total nuts and tree nuts, including walnuts, almonds, cashews, peanuts, and pistachios, has been reported across meta-analyses in decreasing total cholesterol (mean difference, MD, -0.09 to -0.28 mmol/L), LDL-cholesterol (MD, -0.09 to -0.26 mmol/L), and triglycerides (MD, -0.05 to -0.17 mmol/L). However, no effects on HDL-cholesterol have been uncovered. Preliminary evidence indicates that adding nuts into the regular diet reduces blood levels of apolipoprotein B and improves HDL function. There is also evidence that nuts dose-dependently improve lipids and lipoproteins. Sex, age, or nut processing are not effect modifiers, while a lower BMI and higher baseline lipid concentrations enhance blood lipid/lipoprotein responses. While research is still emerging, the evidence thus far indicates that nut-enriched diets are associated with a reduced number of total LDL particles and small, dense LDL particles. In conclusion, evidence from clinical trials has shown that the consumption of total and specific nuts improves blood lipid profiles by multiple mechanisms. Future directions in this field should include more lipoprotein particle, apolipoprotein B, and HDL function studies. https://doi.org/10.3390/nu15030596
Adding Walnuts to the Usual Diet Can Improve Diet Quality in the United States: Diet Modeling Study Based on NHANES 2015–2018.
Background: The under-consumption of calcium, potassium, fiber, and vitamin D is considered a U.S. public health concern. Shifts in eating patterns that increase the consumption of vegetables, fruits, whole grains, nuts/seeds, and dairy products can help achieve the recommended intakes of these nutrients, leading to healthier diets. Objective: We assessed the impact of adding 1 ounce (28.35 g) of walnuts to usual diets on diet quality and nutrients of concern, including magnesium, fiber, and potassium. Methods: We utilized 24 h dietary recalls obtained from the What We Eat in America, National Health and Nutrition Examination Survey (NHANES) and modeled the addition of 1 ounce (28.35 g) of walnuts to the usual diets of no-nut consumers. No-nut consumers aged ≥4 years (n = 7757) from the 2015–2018 NHANES study were included. Population percentages with intakes below the estimated average requirement (EAR) values for calcium, magnesium, folate, and vitamin E and above the adequate intake (AI) values for potassium and fiber were examined. Diet quality was assessed using the Healthy Eating Index-2015 (HEI-2015). The National Cancer Institute method was used to estimate the usual and modeled intakes. Significant differences between usual (current) and modeled intakes were determined using non-overlapping 95% confidence intervals. All analyses included sample weights to account for the NHANES survey design. Results: Adding 1 ounce (28.35 g) of walnuts to the usual diet resulted in significant reductions in the percentages of adults with intakes below the EAR for magnesium and folate (69.6% vs. 52.0%; 49.2% vs. 40.6%, respectively), and increased the percentage of adults above the AI for potassium (22.8% vs. 26.5%). A similar trend was observed among children (4–18 years). HEI scores improved significantly from 49.1 (95% CI: 48.0–50.4) to 58.5 (95% CI: 57.5–59.6) in children and from 52.4 (95% CI: 51.0–53.8) to 59.2 (95% CI: 58.0–60.5) in adults. Conclusions: Adding 1 ounce (28.35 g) of walnuts to the usual diet of no-nut consumers improved the diet quality and adequacy of some under-consumed nutrients. https://doi.org/10.3390/nu15020258
Nuts and Cardiovascular Disease Outcomes: A Review of the Evidence and Future Directions.
Nuts are nutrient-rich foods that contain many bioactive compounds that are beneficial for cardiovascular health. Higher consumption of nuts has been associated with a reduced risk of several cardiovascular diseases (CVD) in prospective cohort studies, including a 19% and 25% lower risk of CVD incidence and mortality, respectively, and a 24% and 27% lower risk of coronary heart disease incidence and mortality, respectively. An 18% lower risk of stroke mortality, a 15% lower risk of atrial fibrillation, and a 19% lower risk of total mortality have also been observed. The role of nuts in stroke incidence, stroke subtypes, peripheral arterial disease and heart failure has been less consistent. This narrative review summarizes recommendations for nuts by clinical practice guidelines and governmental organizations, epidemiological evidence for nuts and CVD outcomes, nut-containing dietary patterns, potential mechanisms of nuts and CVD risk reduction, and future research directions, such as the use of biomarkers to help better assess nut intake. Although there are still some uncertainties around nuts and CVD prevention which require further research, as summarized in this review, there is a substantial amount of evidence that supports that consuming nuts will have a positive impact on primary and secondary prevention of CVD. https://doi.org/10.3390/nu15040911
Nuts as Part of the Mediterranean Diet, Mentioned in Nature Medicine
Nature Medicine, one of the most prestigious medical journals worldwide, has published its "Year in Review" article featuring “11 clinical trials that will shape medicine in 2023”, and the PREDIMED-Plus study on the Mediterranean diet, which among other foods includes nuts. Prof. Jordi Salas-Salvadó, Chairman of the INC World Forum for Nutrition Research and Dissemination, was interviewed among other leading scientists who were asked to name their top clinical trials for 2023. The answers spanned a wide range of fields, from cancer screening to new drugs for Parkinson’s and Alzheimer’s disease.
Prof. Salas-Salvadó, a Distinguished Professor of Nutrition at Rovira i Virgili University in Spain, cited the PREDIMED-Plus clinical trial, for which he serves as principal coordinator and chair of the steering committee. With 6,874 participants recruited in 23 centers and hospitals, PREDIMED-Plus is a milestone of nutritional research. This trial aims to evaluate the long-term effect of an intensive weight-loss intervention based on an energy-restricted Mediterranean diet, physical activity and behavioral support.
“No study has ever demonstrated that weight loss and maintenance using an energy-reduced healthy diet and physical activity lowers the risk of cardiovascular disease in people who are overweight or who have obesity,” Prof. Salas-Salvadó told Nature Medicine. “We hypothesize that an intensive lifestyle-intervention program aimed at weight loss and based on the traditional Mediterranean diet is a sustainable long-term approach for achieving weight loss in overweight and obese adults, and that the lifestyle changes achieved will have a beneficial effect on cardiovascular morbidity and mortality.”
Arnold, C., Webster, P. 11 clinical trials that will shape medicine in 2023. Nature Medicine 28, 2444–2448 (2022). https://doi.org/10.1038/s41591-022-02132-3
PREDIMED-Plus Clinical Trial: https://www.predimedplus.com/en/
Nuts in the Prevention and Management of Type 2 Diabetes.
Diabetes is a continuously growing global concern affecting >10% of adults, which may be mitigated by modifiable lifestyle factors. Consumption of nuts and their inclusion in dietary patterns has been associated with a range of beneficial health outcomes. Diabetes guidelines recommend dietary patterns that incorporate nuts; however, specific recommendations related to nuts have been limited. This review considers the epidemiological and clinical evidence to date for the role of nut consumption as a dietary strategy for the prevention and management of type 2 diabetes (T2D) and related complications. Findings suggest nut consumption may have a potential role in the prevention and management of T2D, with mechanistic studies assessing nuts and individual nut-related nutritional constituents supporting this possibility. However, limited definitive evidence is available to date, and future studies are needed to elucidate better the impact of nuts on the prevention and management of T2D. https://doi.org/10.3390/nu15040878