Biofortification of soybean meal: immunological properties of the 27 kDa γ-zein

Recent progress in using zein nanoparticles-loaded nanocomposites for food packaging applications

Biopolymers are important due to their exceptional functional and barrier properties and also their non-toxicity and eco-friendly nature for various food, biomedical, and pharmaceutical applications. However, biopolymers usually need reinforcement strategies to address their poor mechanical, thermal, and physical properties as well as processability aspects. Several natural nanoparticles have been proposed as reinforcing agents for biopolymeric food packaging materials. Among them, zein nanoparticles (ZNPs) have attracted a lot of interest, being an environmentally friendly material. The purpose of the present review paper is to provide a comprehensive overview of the ZNPs-loaded nanocomposites for food packaging applications, starting from the synthesis, characteristics and properties of ZNPs, to the physicochemical properties of the ZNPs-loaded nanocomposites, in terms of morphology, permeability, solubility, optical features, hydrophobic/hydrophilic behavior, structural characteristics, thermal features, and mechanical attributes. Finally, at the end of this review, some considerations about the safety issues and gastrointestinal fate of ZNPs, as well as the use of ZNPs-based nanocomposites as food packaging, are reported, taking into account that, despite the enormous benefits, nanotechnology also presents some risks associated to the use of nanometric materials.

The Effect of Size, Dose, and Administration Route on Zein Nanoparticle Immunogenicity in BALB/c Mice

Background

Zein-based carriers are a promising delivery system for biomedical applications. However, few studies involve systematic investigation on their in vivo biocompatibility and immunogenicity.

Purpose

The objective of this study was to identify the immunogenicity, type of immune response, biocompatibility and systemic recall immune response of zein nanoparticles administrated via different routes in mice.

Animals and methods

Female Balb/c mice were selected as the animal model in this paper. The effect of particle size, dose and inoculation routes on immunogenicity were systematically explored. The mice were challenged at week 50 via intramuscular and subcutaneous routes to investigate the systemic recall immune responses of zein nanoparticles. Hematoxylin and eosin staining was performed to investigate the biocompatibility of zein nanoparticles at injection sites.

Results

The administration of zein particles by parenteral routes led to a long-term systemic immune response. Particle size did not affect zein-specific IgG antibody titers. IgG antibody titers and inflammatory cell infiltration at the injection sites resulting from intramuscular zein particle injection were significantly higher than those from subcutaneous injection of the same dose. For intramuscular inoculation, dose-dependent IgG antibody titers were observed after the third inoculation, while no significant difference was found via the subcutaneous route. For both routes, IgG titer showed a time-dependent decrease at all dose levels from week 5 onward, and finally plateaued at week 28. The IgG subtype assay showed a predominant Th2-type immune response for both administration routes. Challenge with zein nanoparticles at week 50 led to a significant increase in specific IgG titer at all dose levels, indicating systemic recall immune responses. Interestingly, IgG antibody levels in the subcutaneous groups showed a delayed decrease compared to those of the intramuscular injection groups at all dose levels.

Conclusion

This study indicated that immunogenicity may be one of the key challenges of using zein nanoparticles as carriers via parenteral administration. Further investigation is needed to illustrate zein immunogenicity in other forms, and the possible effect of systemic recall immune response on in vivo pharmacokinetic characteristics.

Comparative analysis of the accelerated aged seed transcriptome profiles of two maize chromosome segment substitution lines

Seed longevity is one of the most essential characteristics of seed quality. Two chromosome segment substitution lines, I178 and X178, which show significant differences in seed longevity, were subjected to transcriptome sequencing before and after five days of accelerated aging (AA) treatments. Compared to the non-aging treatment, 286 and 220 differentially expressed genes (DEGs) were identified after 5 days of aging treatment in I178 and X178, respectively. Of these DEGs, 98 were detected in both I178 and X178, which were enriched in Gene Ontology (GO) terms of the cellular component of the nuclear part, intracellular part, organelle and membrane. Only 86 commonly downregulated genes were enriched in GO terms of the carbohydrate derivative catabolic process. Additionally, transcriptome analysis of alternative splicing (AS) events in I178 and X178 showed that 63.6% of transcript isoforms occurred AS in all samples, and only 1.6% of transcript isoforms contained 169 genes that exhibited aging-specific AS arising after aging treatment. Combined with the reported QTL mapping result, 7 DEGs exhibited AS after aging treatment, and 13 DEGs in mapping interval were potential candidates that were directly or indirectly related to seed longevity.

Impact of co-expression of maize 11 and 18 kDa δ-zeins and 27 kDa γ-zein in transgenic soybeans on protein body structure and sulfur amino acid content

The methionine-rich seed storage proteins of maize have been expressed in transgenic plants as a means to improve the overall sulfur amino acid content of seed. Previous attempts to increase the sulfur amino acid content of soybean seeds by this approach has met with limited success. It has been shown co-expression of different class of zeins can result in their stable accumulation in transgenic plants. In this study, conventional crosses between transgenic plants individually expressing 11, 18 kDa δ-zeins and 27 kDa γ-zein were made to obtain plants that simultaneously express both the δ-zein and γ-zein. Transmission electron microscopic observation of thin-sections of transgenic soybean seeds revealed that the zeins accumulated in ER-derived protein bodies (PBs) which were found sparsely scattered in cytoplasm. The size of these PBs varied from 0.2 to 0.6 μm in soybean plants individually expressing 11, 18 kDa δ-zeins and 27 kDa γ-zein. In contrast, soybeans co-expressing the 18 kDa δ-zein and 27 kDa γ-zein the PBs was 3-4 times larger. Electron microscopic observation also revealed the sequestration of PBs inside the vacuoles where they could be subjected to degradation by vacuolar proteases. Amino acid analysis of transgenic soybean individually expressing 11, 18 kDa δ-zeins and 27 kDa γ-zein revealed only a minimal increase in the overall methionine content compared to the wild-type. In contrast, plants co-expressing 18 kDa δ-zein and 27 kDa γ-zein showed a significant increase (27%) in the methionine content compared to the control seeds.

Identification of an abundant 56 kDa protein implicated in food allergy as granule-bound starch synthase

Rice, the staple food of south and east Asian counties, is considered to be hypoallergenic. However, several clinical studies have documented rice-induced allergy in sensitive patients. Rice proteins with molecular weights of 14-16, 26, 33, and 56 kDa have been identified as allergens. Recently, it was documented that the 56 kDa rice allergen was responsible for rice-induced anaphylaxis. The 14-16 kDa allergens have been identified as α-amylase inhibitors; the 26 kDa protein has been identified as α-globulin; and the 33 kDa protein has been identified as glyoxalase I. However, the identity of the 56 kDa rice allergen has not yet been determined. In this study, we demonstrate that serum from patients allergic to maize shows IgE binding to a 56 kDa protein that was present in both maize and rice but not in the oil seeds soybean and peanut. The 56 kDa IgE-binding protein was abundant in the rice endosperm. We have purified this protein from rice endosperm and demonstrated its reactivity to IgE antibodies from the serum of maize-allergic patients. The purified protein was subjected to matrix-assisted laser desorption ionization-time of flight-tandem mass spectrometry analysis, resulting in identification of this rice allergen as granule-bound starch synthase, a product of the Waxy gene. Immunoblot analysis using protein extracts from a waxy mutant of rice revealed the absence of the 56 kDa IgE-binding protein. Our results demonstrate that the 56 kDa rice allergen is granule-bound starch synthase and raise the possibility of using waxy mutants of rice as a potential source of the hypoallergenic diet for patients sensitized to the 56 kDa rice allergen.

Clinical and nutritional benefits of cysteine-enriched protein supplements

PURPOSE OF REVIEW

To review recently published research into the use of dietary cysteine and/or its derivatives as functional food supplements that will enhance antioxidant status and improve outcome in certain diseases.

RECENT FINDINGS

L-cysteine is now widely recognized as a conditionally essential or (indispensible) sulphur amino acid. It plays a key role in the metabolic pathways involving methionine, taurine and glutathione (GSH), and may help fight chronic inflammation by boosting antioxidant status. In stressed and inflammatory states, sulphur amino acid metabolism adapts to meet the increased requirements for cysteine as a rate-limiting substrate for GSH. Critically ill patients receiving enteral or parenteral nutrition, enriched with cysteine, exhibit decreased cysteine catabolism and improved GSH synthesis. The naturally occurring cysteine-rich proteins, whey or keratin, have the potential to be manufactured into high quality, high cysteine-containing functional foods for clinical investigation.

SUMMARY

Cysteine-rich proteins, such as keratin, may have advantages over the simple amino acid or its derivatives, as nutraceuticals, to safely and beneficially improve antioxidant status in health and disease.