摘要近年来，核桃(Juglans sp.)等坚果引起的过敏性疾病的患病率逐渐增加，人们喜爱食用的以及经常作为加工食品原料的核桃等坚果中存在的过敏原对敏感机体构成了潜在威胁，也成为过敏原监管的一个难题。目前，被人们普遍食用的核桃品种为英国核桃(Juglans regia) 和黑核桃(J. nigra)，这两种核桃品种中已知的过敏原为分属于Prolamins超家族的Jug r 1、Jug n 1、Jug r 3和Cupins超家族的Jug r 2、Jug n 2、Jug r 4，以及Profilins家族的Jug r 5。本文主要对这些核桃过敏原的理化与免疫性质及相关检测方法等方面的研究进展进行了综述，可以系统地了解核桃中的过敏原性质，设计更加准确合理的检测方法，为保障核桃过敏患者的安全提供科学参考。
Abstract：Food allergy has been regarded as an emergent problem of public health. And walnut allergy is one of the most severe food allergies, its prevalence has risen during past decades. As favors food and important food raw material, walnut (Juglans sp.) contains some allergens, which constitute a risk for sensitized individuals, and become an issue of allergen management. Due to the prevalence and severity of walnut allergy, this review intends to provide the up-to-date information about the molecular characterization of walnut allergens, as well as the detection methods of walnut allergens in foods or foodstuffs. At present, the most popular walnut varieties are Juglans regia and J. nigra, and there are many known allergens in both species, Jug r 1, Jug r 2, Jug r 3, Jug r 4 and Jug r 5 in J. regia; Jug n 1 and Jug n 2 in J. nigra. According to their biochemical and immunological characteristics, they are classified into 2 protein superfamilies, the Prolamin superfamily, Jug r 1, Jug n 1 and Jug r 3, and the Cupin superfamily, Jug r 2, Jug n 2 and Jug r 4. The Prolamin superfamily are further divided into 3 classes: 2S albumin, nonspecific lipid transfer protein (nsLTP) and α-amylase/trypsin inhibitor, Jug r 1 and Jug n 1 belong to 2S albumin family, and Jug r 3 belongs to nsLTP. The Cupin superfamily are further divided into 2 classes according to different sedimentation coefficient, 7S globulin and 11s globulin, Jug r 2 and Jug n 2 belong to 7S globulin, Jug r 4 belongs to 11S globulin. Besides, Jug r 5 belongs to the profilins family, a kind of small class of cytosol proteins, which can bind actin, but it is also very little known. In addition, according to the difference in stability, food allergens can be divided into 2 classes, classⅠand class Ⅱ. Food allergens in class Ⅰ are usually with high stability; and food allergens in class Ⅱ is more sensitive to heat or protease treatment, less stable. To date, the vast majority of walnuts allergens belong to classⅠ, except Jug r 5, which belongs to class Ⅱ. Besides, different methods used for the detection of walnuts allergens were also summarized. On the basis of the principle of detection methods, walnut allergens detection techniques are divided into 2 classes, protein-based and DNA-based detection methods. Protein-based detection methods includes protein electrophoresis, immunology methods and mass spectrometry, so far, immunoassay methods are main analysis methods in the detection of walnut allergens. DNA-based detection methods is not completely in view of the allergen proteins, but in view of specific coding sequence of target species, including traditional PCR and RT-PCR, and in recent years, DNA-based detection methods have been widely applied in walnut allergens detection. In general, this paper summarized the physical, chemical and immune properties of different walnut allergens and related detection methods, this may help us understand the nature of walnut allergens better, design more accurate and reasonable detection methods, and this may be very helpful to ensure the safety of walnut allergic patients.
[1] USDA, United States Department of Agriculture - Germplasm ResourcesInformation Network, Beltsville, USA. Available at: http://www.ars-grin.gov/.[2] FAO, Food and Agriculture Organizationof the United Nations, Rome,Italy. Available at: http://www.fao.org/.[3] Chafen JJS, Newberry SJ, Riedl MA et al. Diagnosing and managing common food allergies: a systematic review. [J]. JAMA, 2010, 303:1848–56.[4] Sicherer SH, Sampson HA. Food allergy. [J]. Journal of allergy and clinical immunology, 2010, 125:S116–25.[5] Gupta RS, Springston EE, Warrier MR et al. The prevalence, severity, and distribution of childhood food allergy in the United States. [J]. Pediatrics, 2011, 128:e9–17.[6] Sicherer SH, Mu~noz-Furlong A, Godbold JH, Sampson HA. US prevalence of self-reported peanut, tree nut, and sesame allergy: 11-year follow-up. [J]. Journal of allergy and clinical immunology, 2010, 125:1322–6.[7] Soller L, Ben-Shoshan M, Harrington DW et al. Overall prevalence of self-reported food allergy in Canada. [J]. Journal of allergy and clinical immunology, 2012, 130: 986–8.[8] Sicherer SH, Sampson HA. Food allergy: recent advances in pathophysiology and treatment. [J]. Annual review of medicine, 2009, 60:261–77.[9] Wegrzyn N K, Sampson H A. Adverse reactions to foods [J]. The Medical Clinics of North America, 2006, 90(1), 97-127.[10] Bruijnzeel K C, Ortolani C, Aas K, et al. Adverse reactions to food [J]. Allergy, 1995, 51(8): 623-635.[11] Annick Barre, Jean-Philippe Borges,et al. Homology modelling of the major peanut allergen Ara h 2 and surface mapping of IgE-binding epitopes [J]. Immunology Letters 100, 2005, 153–158.[12] Costa, I. Carrapatoso,et al. Walnut allergens: molecular characterization, detection and clinical relevance [J]. Clinical & Experimental Allergy, 44, 2013, 319–341[13] Breiteneder H. Classifying food allergens. In Koppelman SJ, Hefle SL, Detecting allergens in food. [C]. Boca Raton: CRC Press, 2006.[14] Mills ENC, Jenkins JA, Alcocer MJC, Shewry PR. Structural, biological, and evolutionary relationships of plant food allergens sensitizing via the gastrointestinal tract. [J]. Critical reviews in food science and nutrition, 2004, 44:379–407.[15] Kumar S, Verma AK, Das M, Dwivedi PD. Allergenic diversity among plant and animal food proteins. [J]. Food reviews international, 2012, 28:277–98. [16] Pantoja-Uceda D, Bruix M, Santoro J, et al. Solution structure of allergenic 2S albumins. [J]. Biochemical society transactions, 2002, 30:919–24.[17] Hauser M, Egger M, Wallner M, et al. Molecular properties of plant food allergens: a current classification into protein families. [J]. The Open Immunology Journal, 2008, 1:1–12.[18] NCBI, National Center for Biotechnology Information, Bethesda, USA. Available at: http://www.ncbi.nlm.nih.gov/ .[19] Sordet C, Culerrier R, Granier C et al. Expression of Jug r 1, the 2S albumin allergen from walnut (Juglans regia), as a correctly folded and functional recombinant protein. [J]. Peptides, 2009, 30:1213–21.[20] Teuber SS, Dandekar AM, Peterson WR, et al. Cloning and sequencing of a gene encoding a 2S albumin seed storage protein precursor from English walnut (Juglans regia), a major food allergen. [J]. Journal of allergy and clinical immunology, 1998, 101:807–14.[21] Comstock SS, McGranahan G, Peterson WR, et al. Extensive in vitro cross-reactivity to seed storage proteins is present among walnut (Juglans) cultivars and species. [J]. Clinical and experimental allergy, 2004, 34:1583–90.[22] Hauser M, Roulias A, Ferreira F, Egger M. Panallergens and their impact on the allergic patient. [J]. Allergy asthma and clinical immunology, 2010, 6:1–14.[23] Kader JC. Lipid transfer proteins in plants. [J]. Annu Rev Plant Physiol Plant Mol Biol, 1996, 47:627–54.[24] Yeats TH, Rose JKC. The biochemistry and biology of extracellular plant lipid-transfer proteins (LTPs). [J]. Protein science, 2008, 17:191–8.[25] Asero R, Mistrello G, Roncarolo D et al. Lipid transfer protein: a panallergen in plant-derived foods that is highly resistant to pepsin digestion. [J]. International archives of allergy and immunology, 2001, 124:67–9.[26] Asero R, Mistrello G, Roncarolo D et al. Detection of clinical markers of sensitization to profilin in patients allergic to plant-derived foods. [J]. Journal of allergy and clinical immunology, 2003, 112:427–32.[27] Pastorello E A, Fariolil L, Pravettoni V, et al. Lipid transfer protein and vicilin are important walnut allergens in patients not allergic to pollen [J]. Journal of Allergy and Clinical Immunology, 2004, 114(4): 908-914.[28] Schocker F, L?ttkopf D, Scheurer S et al. Recombinant lipid transfer protein Cor a 8 from hazelnut: a new tool for in vitro diagnosis of potentially severe hazelnut allergy. [J]. Journal of allergy and clinical immunology, 2004, 113:141–7.[29] Pastorello EA, Farioli L, Pravettoni V et al. Lipid transfer protein and vicilin are important walnut allergens in patients not allergic to pollen. [J]. Journal of allergy and clinical immunology, 2004, 114:908–14.[30] Dunwell JM, Purvis A, Khuri S. Cupins: the most functionally diverse protein superfamily? [J]. Phytochemistry, 2004, 65:7–17.[31] Dunwell JM. Cupins: a new superfamily of functionally diverse proteins that include germins and plant storage proteins. [J]. Biotechnology & genetic engineering reviews, 1998, 15:1–32.[32] Radauer C, Breiteneder H. Evolutionary biology of plant food allergens. [J]. Journal of allergy and clinical immunology, 2007, 120:518–25.[33] Breiteneder H, Radauer C. A classification of plant food allergens. [J]. Journal of allergy and clinical immunology, 2004, 113:821–30.[34] Shewry PR, Napier JA, Tatham AS. Seed storage proteins: structures and biosynthesis. [J]. Plant Cell, 1995, 7:945–56.[35] Mills ENC, Jenkins J, Marigheto N, Belton PS, Gunning AP, Morris VJ. Allergens of the cupin superfamily. [J]. Biochemical society transactions, 2002, 30:925–9.[36] Teuber SS, Jarvis KC, Dandekar AM, et al. Identification and cloning of a complementary DNA encoding a vicilin-like proprotein, Jug r 2, from English walnut kernel (Juglans regia), a major food allergen. [J]. Journal of allergy and clinical immunology, 1999, 104:1311–20.[37] Barre A, Sordet C, Culerrier R, et al. Vicilin allergens of peanut and tree nuts (walnut, hazelnut and cashew nut) share structurally related IgE-binding epitopes. [J]. Molecular immunology, 2008, 45:1231–40.[38] Beatriz Cabanillas, E. N. Clare Mills, et al. Characterization of Low Molecular Weight Allergens from English Walnut (Juglans regia). [J]. Journal of agricultural and food chemistry, 2015, 30:925–9.[39] Su M, Venkatachalam M, Teuber SS,et al. Impact of c-irradiation and thermal processing on the antigenicity of almond, cashew nut and walnut proteins. [J]. Journal of the science of food and agriculture, 2004, 84:1119–25.[40] Ling M, Ye J, Beyer K et al. Cloning, identification, and epitope-mapping two black walnut (Juglans niger) allergens. [J]. Journal of allergy and clinical immunology, 2003, 111:S248.[41] Teuber S, Peterson W, Uratsu S, et al. Identification and cloning of Jug r 4, a major food allergen from English walnut belonging to the legumin group. [J]. Journal of allergy and clinical immunology, 2003, 111:S248.[42] Wallowitz M, Peterson WR, Uratsu S, et al. Jug r 4, a legumin group food allergen from walnut (Juglans regia Cv. Chandler). [J]. Journal of agricultural and food chemistry, 2006, 54:8369–75.[43] Beatriz Cabanillas, Jesús F. Crespo, et. Allergenic properties and differential response of walnut subjected to processing treatments. [J]. Food Chemistry, 2014, 141–147[44] Hauser M, Egger M, Wallner M, et al. Molecular properties of plant food allergens: a current classification into protein families. [J]. Open Immunol J, 2008, 1:1–12.[45] Hauser M, Roulias A, Ferreira F, Egger M. Panallergens and their impact on the allergic patient. [J]. Allergy asthma and clinical immunology, 2010, 6:1–14.[46] Witke W. The role of profilin complexes in cell motility and other cellular processes. [J]. Trends in cell biology, 2004, 14:461–9.[47] Costa J, Oliveira MBPP, Mafra I. Novel approach based on single-tube nested real-time PCR to detect almond allergens in foods. [J]. Food research international, 2013, 51:228–35.[48] Schubert-Ullrich P, Rudolf J, Ansari P et al. Commercialized rapid immunoanalytical tests for determination of allergenic food proteins: an overview. [J]. Analytical and bioanalytical chemistry, 2009, 395:69–81.[49] Diaz-Amigo C. Antibody-based detection methods: from theory to practice. In: Popping B, Diaz-Amigo C, Hoenicke K, eds. Molecular biological and immunological techniques and applications for food chemists. [M]. New Jersey: John Wiley & Sons Inc, 2010:223–45.[50] Doi H, Touhata Y, Shibata H et al. Reliable enzyme-linked immunosorbent assay for the determination of walnut proteins in processed foods. [J]. Journal of agricultural and food chemistry, 2008, 56:7625– 30.[51] Sakai S, Adachi R, Akiyama H et al. Determination of walnut protein in processed foods by enzyme-linked immunosorbent assay: inter laboratory study. [J]. Journal of aoac international, 2010, 93: 1255–61.[52] Niemann L, Taylor SL, Hefle SL. Detection of walnut residues in foods using an enzyme-linked immunosorbent assay. [J]. Journal of food science, 2009, 74:T51– 7.[53] Wang H, Li G, Wu Y, Yuan F, Chen Y. Development of an indirect competitive immunoassay for walnut protein component in food. [J]. Food chemistry, 2014, 147:106–10.[54] 王海艳, 袁飞, 吴亚君, 等. 食品中过敏原胡桃蛋白间接竞争ELISA 检测方法研究[J]. 中国食品学报，2010, 10(5)：217-222.[55] Bignardi C, Elviri L, Penna A, et al. Particle-packed column versus silica-based monolithic column for liquid chromatography-electrospray-linear ion trap-tandem mass spectrometry multiallergen trace analysis in foods. [J]. Journal of chromatography a, 2010, 1217:7579–85.[56] Bignardi C, Mattarozzi M, Penna A et al. A rapid size-exclusion solidphase extraction step for enhanced sensitivity in multi-allergen determination in dark chocolate and biscuits by liquid chromatography-tandem mass spectrometry. [J]. Food analytical methods, 2013, 6:1144–52.[57] Heick J, Fischer M, Kerbach S, et al. Application of a liquid chromatography tandem mass spectrometry method for the simultaneous detection of seven allergenic foods in flour and bread and comparison of the method with commercially available ELISA test kits. [J]. Journal of aoac international, 2011, 94:1060–8.[58] Heick J, Fischer M, P?pping B. First screening method for the simultaneous detection of seven allergens by liquid chromatography mass spectrometry. [J]. Journal of chromatography a, 2011, 1218:938–43.[59] Stevenson S E, Woods C A, Hong B, et al. Environmental effects on allergen levels in commercially grown non-genetically modified soybeans: assessing variation across north America. [J]. Frontiers in plant science, 2011, 3: 196-196.[60] Yano T, Sakai Y, Uchida K, et al. Detection of walnut residues in processed foods by polymerase chain reaction[J]. Bioscience, biotechnology, and biochemistry, 2007, 71(7): 1793-1796.[61] Costa J, Oliveira M B P P, Mafra I. Effect of thermal processing on the performance of the novel single-tube nested real-time PCR for the detection of walnut allergens in sponge cakes[J]. Food research international, 2013, 54(2): 1722-1729.[62] Brezna B, Hudecova L, Kuchta T. A novel Real-Time polymerase chain reaction (PCR) method for the detection of walnuts in food [J]. European Food Research and Technology, 2006, 223(3): 373-377.[63] Pilolli R, Monaci L, Visconti A. Advances in biosensor development based on integrating nanotechnology and applied to food-allergen management. [J]. Trac-trends in analytical chemistry, 2013, 47:12–26.[64] Wang W, Li Y, Zhao F, Chen Y, Ge Y. Optical thin-film biochips for multiplex detection of eight allergens in food. [J]. Food research international, 2011, 44:3229–34.[65] 韩远龙, 吴志华, 闫飞, 陈红兵. 花生过敏原检测方法研究进展 [J]. 食品科学, 2012, 33(13): 305-308.[66] Wang Wei, Han Jianxun, Wu Yajun, et al. Simultaneous detection of eight food allergens using optical thin-film biosensor chips [J]. Journal of agricultural and food chemistry, 2011, 59(13): 6889-6894.
