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Celiac peptide-generating α- and γ-gliadins consist of a disordered N-terminal domain extended by an α-helical-folded C-terminal domain. Celiac peptides, primarily located along the disordered part of α- and γ-gliadin molecules, are nicely exposed and directly accessible to proteolytic enzymes occurring in the gastric (pepsin) and intestinal (trypsin, chymotrypsin) fluids. More than half of the potential celiac peptides identified so far in gliadins exhibit cleavage sites for pepsin. However, celiac peptides proteolytically truncated by one or two amino acid residues could apparently retain some activity toward HLA-DQ2 and HLA-DQ8 receptors in docking experiments. Together with the uncleaved peptides, these still active partially degraded CD peptides account for the incapacity of the digestion process to inactivate CD peptides from gluten proteins. In contrast, sourdough fermentation processes involve other proteolytic enzymes susceptible to the deep degradation of celiac peptides. In particular, sourdough supplemented by fungal prolyl endoproteases enhances the degrading capacities of the sourdough fermentation process toward celiac peptides. Nevertheless, since tiny amounts of celiac peptides sufficient to trigger deleterious effects on CD people can persist in sourdough-treated bread and food products, it is advisable to avoid consumption of sourdough-treated food products for people suffering from celiac disease. As an alternative, applying the supplemented sourdough process to genetically modified low gluten or celiac-safe wheat lines should result in food products that are safer for susceptible and CD people.

The S protein forming the homotrimeric spikes of pathogenic beta-coronaviruses, such as MERS-CoV, SARS-CoV and SARS-CoV-2, is a highly glycosylated protein containing mainly N-glycans of the complex and high-mannose type, as well as O-glycans. Similarly, the host cell receptors DPP4 for MERS-CoV and ACE2 for SARS-CoV and SARS-CoV-2, also represent N- and O-glycosylated proteins. All these glycoproteins share common glycosylation patterns, suggesting that plant lectins with different carbohydrate-binding specificities could be used as carbohydrate-binding agents for the spikes and their receptors, to combat COVID19 pandemics. The binding of plant lectins to the spikes and their receptors could mask the non-glycosylated receptor binding domain of the virus and the corresponding region of the receptor, thus preventing a proper interaction of the spike proteins with their receptors. In this review, we analyze (1) the ability of plant lectins to interact with the N- and O-glycans present on the spike proteins and their receptors, (2) the in vitro and in vivo anti-COVID19 activity already reported for plant lectins and, (3) the possible ways for delivery of lectins to block the spikes and/or their receptors.

Sequential IgE-binding epitopes were identified on the molecular surface of the Pis v 1 (2S albumin), Pis v 2 (11S globulin/legumin) and Pis v 3 (7S globulin/vicilin)—major allergens from pistachio (Pistacia vera) seeds—using the Spot technique. They essentially consist of hydrophilic and electropositively charged residues well exposed on the surface of the allergens. Most of the epitopic regions identified on Pis v 1 and Pis v 3 do not coincide with the putative N-glycosylation sites and thus are not considered as glycotopes. Surface analysis of these epitopic regions indicates a high degree of conformational similarity with the previously identified epitopic regions of the corresponding allergens Ana o 1 (vicilin), Ana o 2 (legumin) and Ana o 3 (2S albumin) from the cashew (Anacardium occidentale) nut. These results offer a molecular basis for the IgE-binding cross-reactivity often observed between pistachio and cashew nut. They support the recommendation for prescribing pistachio avoidance in cashew allergic patients. Other conformational similarities were identified with the corresponding allergens Ses i 1 (2S albumin), Ses i 3 (vicilin) and Ses i 6 (legumin) from sesame (Sesamum indicum), and Jug r 1 (2S albumin), Jug r 2 (vicilin) and Jug r 4 (legumin) from walnut (Juglans regia). Conversely, conformation of most of the epitopic regions of the pistachio allergens often differs from that of epitopes occurring on the molecular surface of the corresponding Ara h 1 (vicilin), Ara h 2 (2S albumin) and Ara h 3 (legumin) allergens from peanut (Arachis hypogaea).

Resume Les allergenes polliniques appartiennent a differentes familles de proteines PR (PR pour Pathogenesis-Related), proteines impliquees dans les mecanismes de defense developpes par les plantes : PR-2 ou endo β-glucanases, PR-3 ou chitinases, PR-5 ou thaumatin-like proteines (TLP), PR-10 ou proteines Bet v 1-like, PR-12 ou defensines et PR-14 ou proteines de transfert des lipides (LTP). D’autres allergenes polliniques correspondent a des proteines a role structural (profilines, expansines), metabolique (polcalcine) ou enzymatique (ribonucleases, pectate lyases, polygalacturonases). Les structures trimdimensionnelles de la plupart des allergenes polliniques ont ete caracterisees, les structures manquantes etant souvent accessibles par modelisation moleculaire a partir de patrons structuraux connus. Les epitopes B liant les IgE d’un petit nombre d’allergenes polliniques ont ete identifies par differentes approches (cartes epitopiques et analyse des complexes allergene-IgE), et les epitopes T de nombreux allergenes sont actuellement connus. Le caractere degenere de la reconnaissance des epitopes T par les recepteurs TCR, explique qu’un meme TCR puisse reconnaitre des epitopes T differents et, inversement, qu’un meme epitope T puisse etre reconnu par des TCR differents. L’identification de ces epitopes apporte une contribution essentielle dans differents domaines comme l’utilisation des allergenes polliniques recombinants ou naturels pour le diagnostic biologique des pollinoses ou l’utilisation d’epitopes T en immunotherapie specifique. Ils permettent egalement de predire les possibilites de reactions croisees et de co-sensibilisation entre des allergenes polliniques d’origine differente ou dans le syndrome oral entre des allergenes polliniques et des allergenes de fruits ou de legumes. Ces differents aspects moleculaires sont abordes dans cette revue.

Pathogenic enveloped viruses are covered with a glycan shield that provides a dual function: the glycan structures contribute to virus protection as well as host cell recognition. The three classical types of N-glycans, in particular complex glycans, high-mannose glycans, and hybrid glycans, together with some O-glycans, participate in the glycan shield of the Ebola virus, influenza virus, human cytomegalovirus, herpes virus, human immunodeficiency virus, Lassa virus, and MERS-CoV, SARS-CoV, and SARS-CoV-2, which are responsible for respiratory syndromes. The glycans are linked to glycoproteins that occur as metastable prefusion glycoproteins on the surface of infectious virions such as gp120 of HIV, hemagglutinin of influenza, or spike proteins of beta-coronaviruses. Plant lectins with different carbohydrate-binding specificities and, especially, mannose-specific lectins from the Vicieae tribe, such as pea lectin and lentil lectin, can be used as glycan probes for targeting the glycan shield because of their specific interaction with the α1,6-fucosylated core Man3GlcNAc2, which predominantly occurs in complex and hybrid glycans. Other plant lectins with Neu5Ac specificity or GalNAc/T/Tn specificity can also serve as potential glycan probes for the often sialylated complex glycans and truncated O-glycans, respectively, which are abundantly distributed in the glycan shield of enveloped viruses. The biomedical and therapeutical potential of plant lectins as antiviral drugs is discussed.

Oil bodies, or oleosomes, consist of lipid droplets confined within a protein-containing lipid monolayer that are widely distributed in oil seeds, particularly edible oil seeds. Amphiphilic proteins embedded in the lipid monolayer form an interface between the hydrophobic core of the oil bodies and the hydrophilic cytoplasm in which these organelles are distributed. They also play a crucial role in stabilizing oil bodies and preventing their coalescence via charge and steric hindrances. Oleosins, small proteins measuring 16–25 kDa, are the most abundant amphiphilic proteins occurring in the lipid monolayer surrounding the triglyceride core of oil bodies. They are composed of a hydrophobic α-helical hairpin anchored to the lipid monolayer and extended on both the N- and C-terminal ends by hydrophilic α-helical arms lying on the surface of the lipid monolayer in contact with the cytoplasm. Oleosins from peanut (Ara h 10, Ara h 11, Ara h 14, Ara h 15), hazelnut (Cor a 12, Cor a 13) and sesame (Ses i 4, Ses i 5) have been identified as major lipophilic IgE-binding allergens that are often associated with severe allergic reactions in sensitized subjects. Their allergenicity depends on the occurrence of IgE-binding epitopes along the hydrophilic arms attached to the hydrophobic α-helical hairpin. In addition, the phylogenetic relationships observed between oleosins belonging to different edible oil seeds suggest that some IgE-binding cross-reactivity may occur between oleosins of different origins. However, due to their lipophilic character, they are underrepresented in the water-soluble allergen extracts used in diagnosing food allergies and their role in triggering allergic responses in peanut and other tree nut allergies is thus doubtless greatly underestimated.

The increasing development of edible insect flours as alternative sources of proteins added to food and feed products for improving their nutritional value, necessitates an accurate evaluation of their possible adverse side-effects, especially for individuals suffering from food allergies. Using a proteomic- and bioinformatic-based approach, the diversity of proteins occurring in currently consumed edible insects such as silkworm (Bombyx mori), cricket (Acheta domesticus), African migratory locust (Locusta migratoria), yellow mealworm (Tenebrio molitor), red palm weevil (Rhynchophorus ferrugineus), and giant milworm beetle (Zophobas atratus), was investigated. Most of them consist of phylogenetically-related protein allergens widely distributed in the different groups of arthropods (mites, insects, crustaceans) and mollusks. However, a few proteins belonging to discrete protein families including the chemosensory protein, hexamerin, and the odorant-binding protein, emerged as proteins highly specific for edible insects. To a lesser extent, other proteins such as apolipophorin III, the larval cuticle protein, and the receptor for activated protein kinase, also exhibited a rather good specificity for edible insects. These proteins, that are apparently missing or much less represented in other groups of arthropods, mollusks and nematods, share well conserved amino acid sequences and very similar three-dimensional structures. Owing to their ability to trigger allergic responses in sensitized people, they should be used as probes for the specific detection of insect proteins as food ingredients in various food products and thus, to assess their food safety, especially for people allergic to edible insects.

Cereal food products susceptible to generate immunotoxic peptides play a key role in the epidemiology of celiac disease and associated non IgE-mediated gluten intolerance disorders. The specific recognition by the basket of the HLA-DQ2 and HLA-DQ2 serotype groups of the corresponding immunotoxic peptides, triggers a cascade of molecular recognition events that lead to the inflammatory mechanisms responsible for the erosion of the villi covering the intestinal mucosa, currently observed in the severe forms of celiac disease. Accordingly, different in silico approaches have been proposed to predict the possible occurrence of immunotoxic peptides or immunotoxic-like peptides in food proteins of plant origin and, especially, of edible cereals, to prevent the consumption of deleterious food products by celiac disease suffering people. Among these approaches, the docking of putative imunotoxic-like peptides to the HLA-DQ2 and HLA-DQ8 basket consists of an interesting tool, especially when coupled to the bioinformatic research for amino acid sequence identities with genuine immunotoxic peptides from the gliadin and glutenin proteins already identified in gluten-containing cereals. However, the specificity of the DQ2- and DQ8-peptides has to be checked since some promiscuity has been observed among the immunotoxic peptides concerning their HLA-DQ2/HLA-DQ8-binding specificity. Docking experiments performed with a series of 26 genuine immunotoxic peptides from gluten-containing cereals (wheat, oat, barley, rye) were compared to the glutamine/proline-containing peptides from the non-gluten corn and rice cereals, for their HLA-DQ2/HLA-DQ8-binding capacity. None of the peptides from non-gluten cereals was able to completely bind the HLA-DQ2/HLA-DQ8 basket whereas all of the 26 genuine immunotoxic peptides from the gluten-containing cereals become adequately bound to the HLA-DQ basket, even though some promiscuity occurred between the DQ2- and DQ8-specific peptides. Docking to the HLA-DQ2/HLA-DQ8 serotypes thus consists of a relevant tool to predict the immunotoxic propensity of food proteins toward celiac disease suffering people, provided their sequence are known.

Anaphylactic reactions associated with the consumption of a number of fruits have been identified so far. Stone fruits belonging to the Rosaceae family have been particularly investigated in this respect, due to the occurrence of lipid transfer protein major allergens LTP, in both the pulp and the skin of the fruits. Other offending allergens like the PR-5 thaumatin-like proteins TLP, profilins and a variety of enzymes (β1,3 glucanase, chitinase) also occur in many fruits. However, stone fruits consist of another source of major allergens located in the fruit kernel, namely the cupin and 2S albumin allergens. Cupin allergens consist of three categories of seed storage proteins: germins (

Les oleosomes sont des gouttelettes lipidiques limitees par une monocouche de lipides associee a des proteines (oleosines), repandus dans les graines, notamment dans les oleagineux alimentaires comme l’arachide. Les oleosines (Ara h 10, Ara h 11, Ara h 14, Ara h 15) sont les proteines les plus abondantes des oleosomes. Elles sont constituees d’un cœur hydrophobe de deux helices-a disposees en epingle a cheveu, qui penetre dans le contenu lipidique et assure son ancrage dans l’oleosome. Le cœur hydrophobe est prolonge par deux bras structures en helices-a, hydrophiles, qui s’etalent a la surface de l’oleosome, au contact du cytoplasme. D’autres proteines (caleosines et steroleosines) de structures plus complexes, moins abondantes, jouent aussi un role d’interface avec le cytoplasme. L’IgE-reactivite des oleosines d’arachide a ete detectee par western blot et par une approche Basee sur l’utilisation de microbilles fonctionnalisees liees a un extrait purifie d’oleosines, afin d’augmenter la sensibilite du test de detection. Les deux approches ont permis de detecter l’IgEreactivite de tous les serums (n = 15) de patients allergiques a l’arachide testes, avec toutefois des variations d’intensite importantes. En western blot, un nombre tres limite de serums montre une faible IgE-reactivite avec les caleosines. Ces resultats sont discutes.

To date, a number of mannose-specific lectins have been isolated and characterized from seaweeds, especially from red algae. In fact, man-specific seaweed lectins consist of different structural scaffolds harboring a single or a few carbohydrate-binding sites which specifically recognize mannose-containing glycans. Depending on the structural scaffold, man-specific seaweed lectins belong to five distinct structurally-related lectin families, namely (1) the griffithsin lectin family (β-prism I scaffold); (2) the Oscillatoria agardhii agglutinin homolog (OAAH) lectin family (β-barrel scaffold); (3) the legume lectin-like lectin family (β-sandwich scaffold); (4) the Galanthus nivalis agglutinin (GNA)-like lectin family (β-prism II scaffold); and, (5) the MFP2-like lectin family (MFP2-like scaffold). Another algal lectin from Ulva pertusa, has been inferred to the methanol dehydrogenase related lectin family, because it displays a rather different GlcNAc-specificity. In spite of these structural discrepancies, all members from the five lectin families share a common ability to specifically recognize man-containing glycans and, especially, high-mannose type glycans. Because of their mannose-binding specificity, these lectins have been used as valuable tools for deciphering and characterizing the complex mannose-containing glycans from the glycocalyx covering both normal and transformed cells, and as diagnostic tools and therapeutic drugs that specifically recognize the altered high-mannose N-glycans occurring at the surface of various cancer cells. In addition to these anti-cancer properties, man-specific seaweed lectins have been widely used as potent human immunodeficiency virus (HIV-1)-inactivating proteins, due to their capacity to specifically interact with the envelope glycoprotein gp120 and prevent the virion infectivity of HIV-1 towards the host CD4+ T-lymphocyte cells in vitro.

The use of photodynamic therapy in cancer still remains limited, partly because of the lack of photosensitizer (PS) specificity for the cancerous tissues. Various molecular tools are available to increase PS efficiency by targeting the cancer cell molecular alterations. Most strategies use the protein-protein interactions, e.g. monoclonal antibodies directed toward tumor antigens, such as HER2 or EGFR. An alternative could be the targeting of the tumor glycosylation aberrations, e.g. T/Tn antigens that are truncated O-glycans over-expressed in numerous tumors. Thus, to achieve an effective targeting, PS can be conjugated to molecules that specifically recognize the Oglycosylation aberrations at the cancer cell surface.

International audience; To date, a number of mannose-binding lectins have been isolated and characterized from plants and fungi. These proteins are composed of different structural scaffold structures which harbor a single or multiple carbohydrate-binding sites involved in the specific recognition of mannose-containing glycans. Generally, the mannose-binding site consists of a small, central, carbohydrate-binding pocket responsible for the "broad sugar-binding specificity" toward a single mannose molecule, surrounded by a more extended binding area responsible for the specific recognition of larger mannose-containing N-glycan chains. Accordingly, the mannose-binding specificity of the so-called mannose-binding lectins towards complex mannose-containing N-glycans depends largely on the topography of their mannose-binding site(s). This structure⁻function relationship introduces a high degree of specificity in the apparently homogeneous group of mannose-binding lectins, with respect to the specific recognition of high-mannose and complex N-glycans. Because of the high specificity towards mannose these lectins are valuable tools for deciphering and characterizing the complex mannose-containing glycans that decorate both normal and transformed cells, e.g., the altered high-mannose N-glycans that often occur at the surface of various cancer cells.

International audience; Allergies to animal foods essentially result from the consumption of shellfish, including crustaceans and mollusks, and even edible insects traditionally eaten in different countries around the world. In all of these countries, the statistical data collected during the last decade point out the consumption of shellfish products as a likely cause of the most severe allergic reactions associated to animal-based foods. The allergens responsible for the shellfish allergies mainly consist of pan-allergens belonging to a limited number of protein families, widely distributed in mites, crustaceans, insects, mollusks and nematods. Major allergens are represented by muscle proteins (tropomyosin, troponin C, myosin, sarcoplasmic calcium-binding protein) and enzymes (α-amylase, arginine kinase, glutathione S-transferase, serine protease, triosephosphate isomerase), associated to other functional (hemocyanin, hexamerin) and structural (tubulin) proteins. Most of these pan-allergens exhibit quite well conserved amino acid sequences and readily superposable three-dimensional structures. Although they remain closely phylogenetically-related, they fall into distinct groups more or less distantly related within the phylogenetic trees, depending of the proteins. In this respect, insect tropomyosins fall into two separate groups closely related to mite and crustacean tropomyosin groups, respectively, whereas the mollusk tropomyosin group deviates from all other tropomyosin groups. Alpha-amylase and arginine kinase groups of insects and crustaceans remain closely related but are much more distant from the corresponding groups of mite, mollusk and nematod enzymes. Overall, allergens from insects and crustaceans feel closer whereas mollusks allergens clearly differ from all the other allergen groups. According to these phylogenetic relationships, the IgE-binding cross-reactivities frequently reported between these allergens of different origin could trigger some unexpected crossed allergic reactions in susceptible individuals. In this respect, the consumption of edible insects by shellfish allergic patients should be avoided.; Les allergies alimentaires causées par les aliments d’origine animale proviennent essentiellement de la consommation de crustacés et de mollusques, voire d’insectes comestibles qui commencent à s’introduire sur le marché européen des produits alimentaires. Depuis plusieurs années, les statistiques établies par le CICBAA (centre d’investigations cliniques et biologiques en allergologie alimentaire) soulignent l’importance des crustacés et des mollusques dans la survenue de réactions systémiques sèvères liées à l’alimentation. L’allergénicité de ces aliments dépend de quelques familles d’allergènes communes aux arthropodes, aux mollusques et aux nématodes, qu’il est nécessaire de bien identifier pour diagnostiquer les allergies dont elles sont responsables. Ces allergènes correspondent à des protéines musculaires (tropomyosine, troponine C, myosine, actine, protéine sarcoplasmique fixant le calcium ou SCBP), des enzymes variées (α-amylase, arginine-kinase AK, glutathion S-transférase GST, trypsine, protéase à sérine, triosephosphate isomérase TPI) et des protéines circulantes (hemocyanine, hexamérine) ou structurales (tubulines). La plupart de ces protéines sont ubiquitaires et possèdent des séquences et surtout des structures très conservées et parfaitement superposables. Elles se répartissent dans les arbres phylogénétiques en groupes distincts dont les affinités restent élevées mais peuvent varier considérablement selon les allergènes. Ainsi, les tropomyosines des mollusques s’écartent nettement de celles des autres groupes et les tropomyosines d’insectes se répartissent en deux groupes dont un est proche des tropomyosines des acariens, l’autre des tropomyosines des crustacés. Les α-amylases et les arginine kinases des insectes et des crustacés sont très proches et toujours plus éloignées de celles des acariens, des mollusques et des nématodes. Globalement, les allergènes des insectes et des crustacés paraissent les plus proches tandis que les allergènes des mollusques s’écartent le plus des allergènes des autres groupes. L’existence, souvent rapportée, de réactions croisées entre ces différents groupes d’allergènes laisse présager des possibilités d’allergies croisées entre les acariens, les crustacés, les insectes, les mollusques et les nématodes. En particulier, le risque de réaction allergique associé à la consommation d’insectes comestibles (entomophagie) par des patients allergiques aux crustacés doit être envisagé.

Resume Recemment, l’association de l’allergene Act d 2 du kiwi avec l’allergene Alt a 1 d’Alternaria a ete mise en evidence dans la pulpe du fruit. Cette association repose sur une interaction entre les deux allergenes dont le mecanisme reste encore mal connu. L’allergene Alt a 1 diffuse a partir de la paroi des spores d’Alternaria germant a la surface du fruit, pour migrer dans la pulpe du fruit ou il s’associe avec Act d 2. Cette penetration de l’allergene dans le fruit implique necessairement un franchissement des parois et des membranes cellulaires du fruit par l’allergene. Alt a 1 emprunterait les lenticelles (stomates morts) pour franchir les parois cellulaires et des transporteurs membranaires specifiques pour penetrer dans les cellules de la pulpe. L’association des deux allergenes au sein de la pulpe s’effectuerait grâce a des interactions electrostatiques, hydrophiles et hydrophobes comme le suggerent des experiences d’ancrage moleculaire in silico. Une reconnaissance des chaines glycaniques d’Alt a 1 par la crevasse catalytique d’Act d 2, pourrait egalement intervenir dans cette association. D’autres fruits comme la banane ou la pomme, riches en proteines PR5 thaumatin-like, pourraient presenter ce type d’association. La pertinence clinique possible de cette association repose sur l’observation d’une frequence elevee de cosensibilisations entre Act d 2 et Alt a 1 : 85 % des patients sensibilises a Act d 2 le sont egalement a Alt a 1. Par contre, seulement 39 % des patients sensibilises a Alt a 1 le sont egalement a Act d 2.

International audience; The first documented case report of Japanese lantern fruit (Physalis alkekengi) anaphylaxis caused by a hidden seed cupin allergen, associated with cross-reactivity with the broad bean (Vicia faba) cupin allergen.; Un cas clinique documenté d’anaphylaxie au fruit du Physalis alkekengi dû à des cupines, allergènes cachés des graines, associé à une réactivité croisée avec les allergènes cupines des graines de fève (Vicia faba).

International audience; Allergic diseases have increased its incidence worldwide, increasing the significance of research in diagnostics to offer more precise immunotherapy options. Most current lines of work revolve around single-protein detection, which relies mostly on faint fluorescence signals and large expensive detectors. In this context, we propose a procedure based on visible light absorption by polymeric microparticles. The beads acting as supports react with the serum of an allergic patient and perform a magnetically-assisted competitive immunoassay, similar to indirect ELISA. Firstly, protein binding on surface and antibody recognition was evaluated by SEM imaging. Then, the procedure sensitivity was determined, were the lowest detected IgE concentration is comparable to commercial standards. Finally, the effects of cross-reactive allergen specimens were assessed, yielding difficulties in detection at antibody concentrations close to the limit of detection. Consequently, we have provided a proof-ofconcept of a microparticle-based competitive immunoassay by visible light absorption analysis.

International audience; Bioinformatics can help scientists to develop hypotheses about proteins that may need to be tested further for risks of causing allergy. In silico methodologies and tools like databases and comparison software, play an important role in the assessment of protein allergenicity and allergenicity mechanisms. They can identify whether a novel protein is an existing allergen and/or has the potential to cross-react with an existing allergen. They cannot identify whether a novel protein will ‘become’ an allergen. AllergenOnline is the tool currently used for the safety assessment of novel proteins, but other tools are also available including the Structural Database of Allergenic Proteins (SDAP) and AllerTOP. Information concerning PeptideRanker, as well as the Hydrophobic Cluster Analysis (HCA) method used for identifying IgE-binding epitopes in food allergens is discussed.

International audience; Aberrant O-glycans expressed at the surface of cancer cells consist of membrane-tethered glycoproteins (T and Tn antigens) and glycolipids (Lewis a, Lewis x and Forssman antigens). All of these O-glycans have been identified as glyco-markers of interest for the diagnosis and the prognosis of cancer diseases. These epitopes are specifically detected using T/Tn-specific lectins isolated from various plants such as jacalin from Artocarpus integrifola, and fungi such as the Agaricus bisporus lectin. These lectins accommodate T/Tn antigens at the monosaccharide-binding site; residues located in the surrounding extended binding-site of the lectins often participate in the binding of more extended epitopes. Depending on the shape and size of the extended carbohydrate-binding site, their fine sugar-binding specificity towards complex O-glycans readily differs from one lectin to another, resulting in a great diversity in their sugar-recognition capacity. T/Tn-specific lectins have been extensively used for the histochemical detection of cancer cells in biopsies and for the follow up of the cancer progression and evolution. T/Tn-specific lectins also induce a caspase-dependent apoptosis in cancer cells, often associated with a more or less severe inhibition of proliferation. Moreover, they provide another potential source of molecules adapted to the building of photosensitizer-conjugates allowing a specific targeting to cancer cells, for the photodynamic treatment of tumors.

International audience; Kiwi fruit (Actinidia deliciosa, A. chinensis) is an important source of food allergy in children and adults in Western countries. The allergens responsible for this food allergy consist primarily of typical fruit allergens, e.g. the PR 10 Bet v 1-like allergen Act d 8, the cysteine protease actinidin Act d 1, the TLP Act d 2, and a chitinase. All of these allergens from A. deliciosa fruits have their counterparts in A. chinensis fruits. Recently, two other allergens belonging to the cupin superfamily (Act c 12) and the 2S albumin family (Act c 13), found in the kernels of A. chinensis fruit, have been identified as hidden fruit allergens responsible for IgE-binding cross-reactivity with peanuts and tree nuts. The sequential IgE-binding epitope regions of Act c 12 were predicted using a combination of in silico predictive approaches. Sequential IgE-binding epitopes of Act c 12 were predicted on a three-dimensional model of the protein from the amino acid sequence comparisons of the IgE-binding regions of cross-reacting cupins of peanuts and tree nuts. Residues of the sequence stretches exposed at the molecular surface were assigned as cross-reacting IgE-binding regions of Act c 12. In addition to their conformational similarities, these putative IgE-binding epitopes share a high degree of sequence similarity with the corresponding IgE-binding regions of peanut and tree-nut cupin allergens. The Act c 12 allergen offers an interesting example of a hidden fruit allergen likely to trigger allergic responses in individuals previously sensitized to peanut and other three-nut cupin allergens.(C) 2017 Elsevier Masson SAS. All rights reserved.

Resume Traditionnellement confinee a differents pays d’Asie, d’Afrique et d’Amerique du Sud, la consommation d’insectes ou entomophagie commence a s’etendre a l’Europe et aux Etats-Unis. Bien que tres limitee, surtout pour des raisons psychologiques, l’entomophagie tend a se developper avec l’emergence, dans differents pays d’Europe, d’une production industrielle d’insectes comestibles, associee a l’ouverture de restaurants specialises dans des menus a base d’insectes. Malgre l’interet nutritionnel et l’apparente innocuite des insectes comestibles, il convient d’apprecier le risque allergenique qu’ils peuvent representer pour des sujets allergiques aux crustaces, aux acariens ou aux mollusques. Divers pan-allergenes tels que la tropomyosine ou l’arginine-kinase, communs aux insectes, aux crustaces, aux acariens, aux mollusques et aux nematodes, pourraient etre responsables de reactions croisees entre ces organismes d’origine differente. D’autres allergenes, plus specifiques des insectes, pourraient egalement declencher des reactions allergiques. Ces allergenes restent encore tres mal connus et demandent a etre identifies et caracterises. Dans cette attente et en raison de l’existence d’allergenes croisants chez les insectes, il parait prudent de conseiller aux personnes allergiques aux crustaces ou aux mollusques, d’eviter de consommer ce genre de nourriture.

Summary Inflammatory bowel diseases are characterized by a deregulated immune response targeting the gut bacterial flora. Mucosal-associated invariant T (MAIT) cells are major histocompatibility complex (MHC) class Ib-restricted innate-like lymphocytes with anti-bacterial functions. They display an effector/memory phenotype and are found in large numbers in the blood, mucosae and liver. They have also been implicated in inflammatory diseases such as multiple sclerosis. Therefore, we aimed to analyse the possible involvement of MAIT cells in Crohn's disease (CD) and ulcerative colitis (UC). To this end, a phenotypical and functional analysis of MAIT cells isolated from the blood of healthy subjects, CD and UC patients was undertaken. MAIT cells were also quantified in ileal biopsies of CD patients. The frequency of blood MAIT cells was specifically reduced in IBD patients compared with healthy donors, whereas it was dramatically greater in the inflamed versus healthy tissue. MAIT cells were activated as they expressed significantly more the Ki67 antigen, and this was accompanied by phenotypical changes such as increased expression of natural killer (NK)G2D and B and T lymphocyte attenuator (BTLA). Finally, in-vitro-activated MAIT cells from CD and UC patients secreted significantly more interleukin (IL)-17, together with a decreased interferon (IFN)-γ in CD but an increased IL-22 in UC. These data show that MAIT cells are activated in IBD, which results in an increased recruitment towards the inflamed tissues, an altered phenotype and a switch in the pattern of cytokine secretion. This is the first demonstration that MAIT cells are immune players in IBD, whose precise functions in this context need to be addressed.

Introduction Les globulines 11S (legumines) des graines constituent un groupe important d’allergenes. On les retrouve dans de tres nombreuses graines comestibles : arachide (Ara h 3), pistache (Pis v 2), noix de Cajou (Ana o 2), noix (Jug r 4), noisette (Cor a 9), amande (Pru du 6), soja (Gly m), sesame (Ses i 6), sarrasin (Fag e 13), etc. Ces allergenes presentent souvent une reactivite croisee importante. Recemment, une reactivite croisee a ete mise en evidence entre l’allergene masque Act d 12 des graines de kiwi et les cupines 11S de l’arachide, de l’amande, de la noisette et, plus rarement, de la noix. Methodes Une comparaison de la conformation des regions epitopiques sur la surface moleculaire de ces allergenes a ete entreprise afin de preciser les bases moleculaires qui sous-tendent cette reactivite croisee. Resultats La recherche d’allergenes homologues d’Act c 12 dans les banques d’allergenes fournit de nombreux homologues et tous ces allergenes possedent la structure tridimensionnelle typique des cupines 11S, constituee de deux homotrimeres superposes. Les sequences d’acides amines de ces allergenes montrent des taux eleves d’identite (55 %) et d’homologie (85 %) avec la sequence d’Act c 12. En particulier, ces identites/homologies s’observent dans certaines des regions epitopiques identifiees dans les allergenes homologues comme Ana o 2 de la noix de Cajou, Cor a 9 de la noisette, Jug r 4 de la noix. Ces regions epitopiques a fort pourcentage d’identite/homologie montrent des conformations tres similaires quand on les observe sur les modeles tridimensionnels d’Act c 12 et des autres allergenes Ana o 2, Cor a 9 et Jug r 4. Conclusion Ces conformations voisines rendent compte de la reactivite croisee observee entre Act d 12 et les autres allergenes de la superfamille des cupines 11S. Les regions epitopiques homologues identifiees sur la surface moleculaire des differents cupines 11S correspondent vraisemblablement a des epitopes consensuels presents chez une majorite de cupines 11S.

Resume Parmi les allergenes majeurs du latex (Hev b 1, Hev b 2, Hev b 4, Hev b 5, Hev b 6.01, Hev b 6.02 et Hev b 13), Hev b 2 et Hev b 13 sont encore mal connus et leur implication dans l’allergie au latex et le syndrome latex-fruits reste a preciser. Ce sont des glycoallergenes ubiquitaires tres largement distribues chez tous les vegetaux, presents en particulier dans les fruits (banane, cerise, kiwi, etc.). Hev b 2 est une endo-β1,3-glucanase impliquee dans le metabolisme glucidique lors du murissement des fruits. Hev b 13 est une esterase intervenant egalement dans le metabolisme. La plupart des epitopes B liant les IgE identifies sur ces deux allergenes ne coincident pas avec l’emplacement des sites de glycosylation et ne correspondent vraisemblablement pas a des glycotopes. La prevalence elevee de ces deux allergenes dans les populations allergiques souligne leur importance dans le diagnostic de l’allergie au latex et du syndrome latex-fruits.

Resume Les allergenes majeurs de l’arachide, des fruits a coque et des autres graines comestibles correspondent essentiellement a des proteines de reserve s’accumulant dans les corps proteiques au cours de la maturation de la graine. Les globulines a motifs cupine sont les proteines de reserve les plus abondantes. On les subdivise en globulines 7S ou vicillines et globulines 11S ou legumines. Les vicillines resultent de l’association non covalente de trois monomeres constitues d’une seule chaine peptidique, en un homotrimere aplati de forme triangulaire. Les legumines se distinguent des vicillines par des monomeres a deux chaines peptidiques qui s’associent en homotrimeres puis, deux trimeres s’associent en hexamere. A la difference des legumines qui sont rarement glycosylees, les vicillines sont generalement N-glycosylees. Les vicillines et legumines sont largement distribuees dans les graines de nombreuses familles vegetales ou elles ont ete identifiees (Ara h 1 et Ara h 3 de l’arachide) ou seulement suspectees (germine de la châtaigne) comme allergenes majeurs. En raison de leurs fortes homologies sequentielle et structurale, elles donnent lieu a de nombreuses reactions croisees dont la signification clinique n’a pas toujours ete demontree.

Resume La consommation de noix de Cajou grillees ou de produits alimentaires en contenant sous forme d’allergenes caches (plats cuisines asiatiques, glaces, gâteaux) peut provoquer des reactions anaphylactiques severes chez les individus sensibilises. Comme l’allergie a l’arachide, l’allergie a la noix de Cajou est rapidement devenue un probleme de sante publique en raison de la gravite des symptomes. Les allergenes majeurs de la noix de Cajou correspondent a des proteines de reserve qui se concentrent dans les corps proteiques de la graine, ce sont Ana o 1 (vicilline) et Ana o 2 (legumine) de la famille des cupines, et Ana o 3 (albumine 2S). Ces allergenes, qui resistent bien a la denaturation thermique (rotissage) et a l’hydrolyse par les proteases digestive (pepsine, trypsine), ont une allergenicite elevee. Les epitopes B liant les IgE ont ete identifies sur la surface moleculaire de ces allergenes. D’importantes reactions croisees sont observees avec les allergenes homologues Pis v 1, Pis v 2 et Pis v 3, de la pistache. Cette reactivite croisee depend des homologies de sequence et de structure observees entre ces allergenes. Des reactions croisees moins frequentes sont observees avec d’autres fruits a coque, l’amande et la noisette en particulier. En revanche, il n’existe pratiquement pas de reactivite croisee entre la noix de Cajou et l’arachide. A ce propos, il est a noter que la noix de Cajou et la pistache appartiennent a la meme famille des Anacardiacees et sont tres proche phylogenetiquement.

Porphyrins are used as photosensitizer (PS) in photodynamic therapy in cancer treatment. Nevertheless, the development of photochemotherapy in oncology remains limited, because of the low selectivity of PSs. In order to allow PS targeting toward tumor-associated antigens, for the first time a white-light activatable porphyrin, [5-(4-(5-carboxy-1-butoxy)-phenyl)-10,15,20-tris(4-N-methyl)-pyridiniumyl)-porphyrin] (TrMPyP) was covalently linked to Morniga G (MorG), a galactose-specific binding plant lectin, known to recognize with high-affinity tumor-associated T/Tn antigen in cell-free systems. Firstly, using fluorescein-labeled MorG, the sugar-dependent binding and uptake of lectin by Tn-positive (Jurkat lymphoid leukemia) cells was demonstrated. Secondly, the TrMPyP-MorG conjugate was molecularly characterized. Cytometric and confocal microscopic analysis demonstrated that PS covalent linking to MorG preserved sugar-dependent specific binding and uptake of lectin by Jurkat leukemia lymphocytes. Thirdly, the conjugate (with a 1:1 PS:lectin ratio) that was bound and quickly (5 min) taken-up, induced greater than 90% cytotoxicity upon irradiation at 10 nm concentration, whereas the free PS was absolutely nontoxic. On the contrary, normal lymphocytes strongly resisted to the conjugate-mediated phototoxicity. Thus, owing to their binding and endocytosis capacities, plant lectins represent promising molecules for targeting of tumor glycan alteration and to enhance the efficiency of specific delivery of PSs to tumor cells.

The lipid transfer protein of apple fruit, Mal d 3, has been produced as a soluble recombinant protein in transformed Escherichia coli cells using the GATEWAY technology. Circular dichroism spectra showing the protein essentially consists of alpha-helices indicate that the rMal d 3 is properly folded. The (1)H NMR spectra also indicates a correct fold for the recombinant allergen. The reactivity of rMal d 3 towards IgE from apple allergic patients and in vitro degranulation activity measured on transformed rat basophil leukemia cells expressing the human Fc epsilon RI alpha-subunit of rMal d 3 is similar to those of the native allergen purified from apple fruits. The expression of active rMal d 3 in E. coli is readily feasible and offers an interesting alternative to the production of recombinant allergen in the yeast Pichia pastoris. This expression in E. coli open the way to the modification of Mal d 3 by site-directed mutagenesis for immunotherapy purposes.

Resume Les lectines vegetales ou agglutinines sont des proteines de reconnaissance qui interagissent specifiquement avec les glycanes des surfaces cellulaires. Les lectines de legumineuses sont classees en plusieurs groupes en fonction des sucres simples qu’elles reconnaissent. Les principales appartiennent a deux categories : les lectines galactose-specifiques (lectine de l’arachide [PNA]), lectine du soja (SBA) et les lectines mannose-specifiques (lectine du pois [PSA], lectine de lentille [LCA]). La PNA, localisee dans les corps proteiques de la graine, a ete decrite comme un allergene mineur de l’arachide (Ara h agglutinin). Elle reconnait specifiquement les glycanes termines par un galactose et a ete utilisee pour isoler les lymphocytes T. La majorite des serums d’allergiques a l’arachide interagissent avec la PNA. Ces serums interagissent aussi avec des lectines voisines, la PSA ou la LCA, mais beaucoup moins avec la SBA ou la PHA de haricot. Les epitopes liant les IgE ont ete identifies sur la surface moleculaire de la PNA. Quelques uns d’entre eux presentent des homologies structurales avec ceux des PSA et LCA. Ces homologies structurales expliqueraient les reactions croisees observees entre la PNA et les autres lectines de legumineuses.

Resume Les fruits comestibles renferment de nombreux allergenes qui correspondent essentiellement a des proteines de defense ou proteines PR (pour Pathogenesis Related). Ces proteines, tres repandues chez les vegetaux, sont des panallergenes. Les principaux allergenes appartiennent aux groupes des PR-2 (1,3β-glucanases), des PR-3 (chitinases de classe I), des PR-4 (transporteurs d’auxine ou germines), des PR-5 (proteines thaumatine-like ou TLP), des PR-10 (proteines Bet v 1-like) et des PR-14 (proteines de transfert des lipides ou LTP). S’y ajoutent des profilines et des pectine esterases. En raison de la presence de ces allergenes dans les pollens, les aeroallergenes sont le plus souvent responsables de la sensibilisation primaire. Ainsi, la plupart des allergies a la pomme dependent d’une sensibilisation prealable au pollen de bouleau, l’allergene Mal d 1 croisant avec Bet v 1. L’allergie au kiwi ou a la banane sont souvent associees aux allergenes croisants (chitinases, 1,3β-glucanases) du syndrome latex-fruits. La sensibilisation directe par contact ou ingestion (LTP de peche) est possible et peut donner lieu a des reactions anaphylactiques generalisees, notamment dans les pays du Sud de l’Europe (Espagne). Le diagnostic biologique des allergies aux fruits est souvent delicat en raison du petit nombre d’allergenes recombinants disponibles (rPru p 1, rPru p 3 et rPru p 4 de peche) et de l’instabilite des extraits de fruits.

Jug r 1, the 2S albumin allergen from walnut, was isolated from ripe nuts as a native allergen and expressed in Escherichia coli using the Gateway ® technology as a recombinant allergen. The recombinant Jug r 1 (15 kDa) differs from the native allergen by the absence of cleavage of the polypeptide chain in two covalently associated light (3.5 kDa) and heavy (8 kDa) chains. Recombinant rJug r 1 adopts the canonical α-helical fold of plant 2S albumins as checked on CD spectra. Four IgE-binding epitopic stretches were identified along the amino acid sequence of Jug r 1 and localized on the molecular surface of the modeled allergen. Both native and recombinant allergens exhibit similar IgE-binding activity and similarly trigger the degranulation of a FcɛRI-expressing rat basophilic leukaemia cell line previously treated by IgE-containing sera. Native Jug r 1 resists to heat denaturation and to the proteolytic attack of trypsin and chymotrypsin but is readily hydrolyzed in the presence of pepsin at acidic pH after 1 h of incubation at 37 °C in vitro . Recombinant Jug r 1 could be used for a component-resolved diagnosis of food-allergy.

Resume Les structures moleculaires des principaux allergenes de l’arachide et des fruits a coque actuellement disponibles ont ete caracterisees principalement par modelisation moleculaire, plus rarement par cristallographie ou resonance magnetique nucleaire (RMN). Ces allergenes appartiennent essentiellement aux groupes : (1) des legumines et vicillines a motif cupine (Ara h 1, Ara h 3/4, legumines et vicilines des fruits a coque) ; (2) des albumines 2S (Ara h 2, Ara h 6, Ara h 7, albumines 2S des fruits a coque) ; (3) des profilines (Ara h 5) ; (4) des proteines PR-10 (Ara h 8) ; (5) des lipid transfer proteins (LTP) (Ara h 9) et (6) des lectines (Ara h agglutinine ou peanut agglutinin [PNA]). Il s’agit essentiellement de proteines de reserve des corps proteiques des graines dont la resistance a la denaturation thermique et a la proteolyse est variable mais souvent elevee. En outre, les oleosines, qui se concentrent dans les corpuscules lipidiques de la graine (oleosomes), ont ete recemment caracterisees comme des allergenes majeurs. Les epitopes liant les IgE (epitopes B) ont ete localises a la surface des allergenes majeurs de l’arachide (Ara h 1, Ara h 2, Ara h 3). L’existence d’epitopes communs est a l’origine de reactions croisees entre l’arachide et les fruits a coque dont la signification clinique n’est pas toujours evidente. Jusqu’a present, tres peu d’informations sont disponibles sur les epitopes T des allergenes de l’arachide a l’exception des epitopes T d’Ara h 2 qui ont ete caracterises. Ces avancees sur la localisation des epitopes B et T sur la surface moleculaire des allergenes sont un prerequis pour l’elaboration d’hypoallergenes recombinants utilisables en immunotherapie.

Resume Les principaux allergenes des fruits de Rosacees (Prunoidees) correspondent a des proteines de defense (proteines pathogenesis-related [PR]) qui sont essentiellement exprimees en reponse a l’attaque de la plante par un champignon phytopathogene. Il s’agit des proteines de transfert des lipides (LTP), des 1,3β-glucanases et des proteines thaumatin-like (TLP), qui appartiennent respectivement aux familles des proteines PR-14, PR-2 et PR-5. La LTP de pomme (Mal d 3) est principalement localisee dans la peau du fruit et la peau de certaines varietes de pomme (Granny Smith, Golden delicious, Fuji) est particulierement riche en LTP. La chair du fruit en renferme beaucoup moins. La LTP de peche (Pru p 3) s’accumule essentiellement dans les poils formant le revetement duveteux du fruit. En pratique, l’epluchage de ces fruits reduit considerablement l’apport de LTP aux personnes sensibilisees. En revanche, la cuisson des fruits n’offre aucun interet en raison de l’extreme resistance des LTP a la denaturation thermique. Dans d’autres fruits, prune (Pru d 3) et abricot (Pru ar 3), les LTP sont aussi abondantes dans la peau que dans la chair et l’epluchage de ces fruits ne reduit en rien leur allergenicite. Des resultats preliminaires semblent indiquer que les fruits issus de l’agriculture biologique possedent des teneurs en LTP superieures a celles observees dans les fruits issus de l’agriculture traditionnelle. Dans les pays du pourtour Mediterraneen, l’Espagne et l’Italie en particulier, l’allergie a la peche (Pru p 3) s’accompagne souvent de reactions anaphylactiques severes.

Resume Les proteines de transfert des lipides (Lipid Transfer Proteins [LTP]) sont des phytoallergenes importants des fruits de Rosacees (prunoidees). En raison de leur caractere ubiquitaires, les LTP sont distribuees dans d’autres organes (feuilles, racines, graines). Ce sont des proteines de petite taille (10 kDa) d’environ 90 acides amines constituees d’helices α qui adoptent une structure compacte en forme de saxophone. Quatre ponts disulfures conserves relient les differentes regions de la chaine polypeptidique assurant a ces proteines une resistance remarquable a la denaturation thermique (cuisson) et a l’attaque des proteases digestives. Cette resistance rend compte en grande partie de leur allergenicite. L’allergenicite des LTP est liee a trois epitopes liant les IgE exposes en surface. L’epitope 2 est un epitope consensus conserve dans de nombreuses LTP de fruits (raisin), du latex (Hev b 9) ou de graines (Cor a 8 de la noisette). Les reactivites croisees entre LTP d’origine tres differente sont frequentes en raison de cette communaute epitopique. Les profils cliniques des patients allergiques a la peche different enormement entre le Nord et le Sud de l’Europe. En Espagne, la sensibilisation a la peche se fait par contact direct avec la LTP (Pru p 3) du fruit et n’est generalement pas associee a une pollinose. Elle se traduit souvent par des reactions generalisees. Aux Pays-Bas et en Autriche, la sensibilisation s’effectue par l’intermediaire de Bet v 1 du pollen de bouleau et l’allergie a la peche depend d’une reaction croisee entre Bet v 1 et son homologue Mal d 1 de pomme.