Emerging Allergens in Goji Berry Superfruit: The Identification of New IgE Binding Proteins towards Allergic Patients' Sera.

Carina Gabriela Uasuf,Claudia D'Anna,Ignazio Brusca,Danilo Villalta,Elisabetta De Angelis,Rosa Pilolli,Linda Monaci,Rocco Guagnano

doi:10.3390/biom10050689

Abstract

The goji berry (Lycium barbarum L.) (GB) is gaining increasing attention with high consumption worldwide due to its exceptional nutritional value and medicinal benefits displayed in humans. Beyond their beneficial properties, GBs contain renowned allergenic proteins, and therefore deserve inclusion among the allergenic foods capable of inducing allergic reactions in sensitive consumers. GB allergy has been frequently linked to the panallergen lipid transfer protein (LTP), especially across the population of the Mediterranean area. Methods: In this study, we investigated the protein profile of GBs focusing on the most reactive proteins against immunoglobulins E (IgE) of allergic patients’ sera, as ascertained by immunoblot experiments. The protein spots displaying a clear reaction were excised, in-gel digested, and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) followed by data searching against a restricted database for a reliable protein identification. Results: According to our data, three main spots were identified in GB extract as IgE binding proteins after immunoblot analysis. Some major proteins were identified and the three proteins that provided the highest reactivity were putatively attributed to vicilin and legumin proteins followed by a protein matching with 11S globulin belonging to the cupin superfamily. Finally, the whole GB protein extract was also submitted to bottom-up proteomics followed by a software-based database (DB) screening and a more exhaustive list of GB proteins was compiled.

Highlights

Goji berry (GB) which is the fruit of Lycium barbarum is widely consumed across the world and mostly grown in Asiatic countries and cultivated in America, Europe, and Australia [1,2]
We deeply investigated the other immunoreactive proteins extracted from GB and reported a proteomic investigation carried out on GB extracts tailored to the characterization of the most reactive proteins as appeared in the immunoblot experiments performed on two sera of patients sensitized to GB
To better explore the lower molecular weight (MW) range below 25 kDa and in order to confirm their detectability, a second electrophoretic separation was accomplished on a Tris-tricine gel at 16.5% of acrylamide which was capable of better resolving the proteins in the lower MW range

Summary

Introduction

Goji berry (GB) which is the fruit of Lycium barbarum is widely consumed across the world and mostly grown in Asiatic countries and cultivated in America, Europe, and Australia [1,2] This fruit has been included among the officinal plants, becoming part of the traditional medicine in ancient China due to the health benefits promoted in humans. Results obtained through in vitro experiments about the allergenic profile of two patients, showed a 9 kDa band, suggesting that the corresponding protein could be attributed to LTPs. The study demonstrated a high level of homology between LTPs from tomato and GB, which confirmed the homology existing between LTPs from different food species. A recent Portuguese study using plasma of individuals with allergic history to potato and tomato proteins but without a clear history of an allergy to GB identified 11 potential allergens, of which four had never been reported in the Allergome database [10]

Methods

Results

Conclusion