Impact of sulfur and vitamin C on the allergenicity of Mal d 2 from apple (Malus domestica)

Ascorbylation of a Reactive Cysteine in the Major Apple Allergen Mal d 1

The protein Mal d 1 is responsible for most allergic reactions to apples (Malus domestica) in the northern hemisphere. Mal d 1 contains a cysteine residue on its surface, with its reactive side chain thiol exposed to the surrounding food matrix. We show that, in vitro, this cysteine residue is prone to spontaneous chemical modification by ascorbic acid (vitamin C). Using NMR spectroscopy and mass spectrometry, we characterize the chemical structure of the cysteine adduct and provide a three-dimensional structural model of the modified apple allergen. The S-ascorbylated cysteine partially masks a major IgE antibody binding site on the surface of Mal d 1, which attenuates IgE binding in sera of apple-allergic patients. Our results illustrate, from a structural perspective, the role that chemical modifications of allergens with components of the natural food matrix can play.

Selenium biofortification of different varieties of apples (Malus domestica) - Influence on protein content and the allergenic proteins Mal d 1 and Mal d 3

As allergy towards apples is widespread, the evaluation of various cultivation and postharvest influences on the allergenic potential is of great importance. Therefore, the analysis of the Mal d 1 content was the focus of this study, originally dealing with investigating the influence of a selenium biofortification on apple quality. The Mal d 1 content of apples was in most cases reduced when the fruits were biofortified with selenium. Apple variety and climatic conditions were identified as further influencing factors for the Mal d 1 content of the fruits. The separate analysis of the peel and the fruit flesh showed that the content of Mal d 1 in the fruit flesh was significantly lower in the biofortified samples than in the controls. In conclusion, the results indicate that the selenium biofortification of apples and biochemical mechanism behind can reduce the allergenic potential regarding the content of Mal d 1.

Allergen-specific immunotherapy with apples: selected cultivars could be a promising tool for birch pollen allergy

Background

Most birch pollen‐allergic patients develop allergic cross‐reactions to the major allergen found in apples Mal d1, known as pollen‐related food allergy (prFA). This is due to a strong clinically relevant homology between the major allergen in birch Bet v 1 and Mal d 1. Daily apple consumption induces oral tolerance in prFA, but its effect on the inhalational allergy has not been investigated.

Objectives

As continuous apple consumption might also mitigate the inhalational allergy, this study aimed to uncover apple cultivars suitable for treatment of birch pollen rhinoconjunctivitis and apple allergy in a controlled and established dosage.

Methods

Patients (n = 52) with birch pollen allergy and prFA to apples were subjected to a prick‐to‐prick test (SPT) with 23 cultivars (red‐fleshed, old traditional and new commercial). By SPT, the apple parts flesh, peel equatorial and peel apical near the stalk were compared for their reactivity. One apple cultivar of each allergenicity class (low, middle and high) was subsequently tested in an oral provocation test (OPT).

Results

According to the SPTs, we provide a ranking of all 23 cultivars. Red‐fleshed apples displayed the lowest reactivity, followed by old and new cultivars. Four cultivars showed disagreement from their allergenicity class: Santana and Pink Lady®, new cultivars that provoked only low to moderate. In contrast, White Rosemary and Goldparmäne, two old cultivars, induced strong reactions. Skin reactivity increased from flesh to peel to stalk, and SPT results could predict the severity of prFA of each allergenicity class.

Conclusions

Herein, we propose a treatment protocol for allergen immunotherapy to birch pollen and prFA with daily apple consumption. Red‐fleshed, old and the new cultivars Santana and Pink Lady® provoke less allergic reactions and are suitable for initial induction. After a controlled and well‐tolerated increase of intake, also moderate and finally high allergenic apple cultivars should be integrated into treatment of birch pollen allergenic patients.

Linked Commentary: K.‐C. Bergmann. J Eur Acad Dermatol Venereol 2020; 34: 1130–1130. https://doi.org/10.1111/jdv.16556.

Protective effects of aspirin and vitamin C against corn syrup consumption-induced cardiac damage through sirtuin-1 and HIF-1α pathway

Objective:

The aim of this study was to investigate the protective effects of aspirin (AS) and vitamin C (VC) against cardiac damage induced by chronic corn syrup (CS) consumption via a mechanism involving sirtuin-1 (ST-1), hypoxia-inducible factor-1a (HIF-1a), and the caspase-3 pathway in rats.

Methods:

Forty male Sprague–Dawley rats (14–16 weeks) that weighed 250–300 g were randomly distributed into 5 groups, each containing 8 rats: control group, CS+AS group, CS+VC group, CS+AS+VC group, and CS group. AS (10 mg/kg/day) and VC (200 mg/kg/day) were orally given to the rats. F30 (30% fructose syrup solution) was given to the rats in drinking water for 6 weeks. The rats were sacrificed by exsanguination 24 h after the last administration. Blood samples and tissue were collected for biochemical, histopathological, and immunohistochemical examinations. Non-parametric Kruskal–Wallis test and Mann–Whitney U test used for the parameters without normal distribution and ANOVA and post-hoc LSD tests were used for parameters with a normal distribution to compare groups.

Results:

Uric acid, creatine kinase (CKMB), and lactate dehydrogenase (LDH) levels were increased in the CS group compared with the control group (1.45±0.39 and p=0.011; 3225.64±598.25 and p=0.004; 3906.83±1064.22 and p=0.002, respectively) and decreased in all the treatment groups. In addition, increased levels of MDA and decreased activity of CAT in the CS group (0.172±0.03 and p=0.000; 0.070±0.005 and p=0.007, respectively) were reversed with AS and VC therapy. A decrease in ST-1 activity and increases in caspase-3 and HIF-1 activities corrected by VC and AS therapy were observed.

Conclusion:

AS and VC, which display antioxidant and antiapoptotic activities, ameliorated cardiac damage induced by chronic fructose consumption by increasing the levels of ST-1 and decreasing the levels of HIF-1a and caspase-3.