Anti-allergic activity of grapeseed extract (GSE) on RBL-2H3 mast cells

Grapeseed extract (GSE) is a rich source of natural phenolic compounds and possesses various pharmacological activities, including antioxidant, anticarcinogenic and anti-inflammatory properties. However, effects of GSE on immunoglobulin (Ig) E-mediated allergic responses still remain elusive. In the present study, the effects of GSE on activation and degranulation of RBL-2H3 mast cells were investigated. GSE pretreatments (20-100 μg/ml) reduced IgE-antigen mediated release of β-hexosaminidase and histamine in RBL-2H3 cells. Additionally, GSE reversibly inhibited expression of FcεRI on RBL-2H3 cells. GSE treatments caused a significant elevation of intracellular cAMP levels, whereas the Ca²⁺ influx upon antigen stimulation was inhibited. Suppression on FcεRI expression together with decreased calcium uptake and increased cAMP level might be involved in attenuated degranulation of mast cells by GSE treatment. Our results suggest a possible pharmaceutical application of GSE in treating type I allergic diseases.     

Practical and predictive bioinformatics methods for the identification of potentially cross-reactive protein matches

A bioinformatics comparison of proteins introduced into food crops through genetic engineering provides a mechanism to identify those proteins that may present an increased risk of allergic reactions for individuals with existing allergies. The goal is to identify proteins that are known to be allergens or are so similar to an allergen that they may induce allergic cross-reactions. Three comparative approaches have traditionally been used, or considered for safety evaluations. One identifies any short (6-8) amino acid segment of the protein that exactly matches a known allergen sequence. The second is an overall primary sequence comparison using Basic Local Alignment Search Tool (BLAST) or FASTA to find matches of greater than 35% identity over 80 amino acids. The third is based on 3-D prediction programs to identify 3-D similarities that might predict potential cross-reactivity. The utility of each of these approaches was debated in the bioinformatics workshop. The consensus agreement from the expert workshop participants was that the short-segment match (e. g., 6-8 amino acids) provides an unacceptably high rate of false positive matches and an uncertain rate of true positive matches, and was not particularly useful for an allergenicity evaluation performed in the context of comprehensive safety evaluation. There was no consensus regarding the most appropriate bioinformatics method, an acceptable scoring criteria for triggering closer examination subsequent to a positive match, or an acceptable scoring mechanism for ranking the utility of the various 3-D approaches that were discussed during the workshop. However, the general consensus was that the most practical approach at this time is to evaluate primary sequence identities to known allergens using either FASTA or BLAST. While there was good agreement that identities of greater than 35% over 80 or more amino acids (recommended by Codex in 2003) is quite conservative, the conclusion was that additional data or studies would be needed to justify changing this criterion as there is some evidence that some individuals sensitized to proteins in evolutionarily conserved protein families may experience cross-reactions to proteins sharing approximately 40% identity.     

Allergen-specific IgE testing in the diagnosis of food allergy and the event of a positive match in the bioinformatics search

Current documents on risk assessment of genetically modified foods recommend including IgE-binding tests on sera from allergic patients. However, there is no generally accepted recommendation on technical aspects of the testing procedures or on the interpretation of the results, despite that fact that both false positive and false-negative results may be caused by variability of the test procedures. The present article discusses the state-of-the-art of serological test procedures for qualitative and quantitative determination of specific IgE and interpretation of test results. It is emphasized that the use of sera from clinically well-characterized subjects is of high importance. In the case of a positive test result, the biological activity of the detected IgE antibodies, i. e., the potential to trigger mediator release from basophils or mast cells in an allergen-specific manner, should be taken into account. However, present data also indicate that validation of such mediator release tests is required, both in terms of experimental protocols and with respect to correlation of the test results with the clinical situation. Further studies are also required to prove the usefulness of targeted serum screening, i. e., the testing of gene products from organisms not known to be allergenic with sera from subjects allergic to related species.     

生物膜干涉法检测花生蛋白与花生过敏患者血清IgE的结合能力

探索基于生物膜干涉技术对花生蛋白与花生过敏患者血清中免疫球蛋白E（immunoglobulin E,IgE）的结合能力进行检测的方法。利用链霉亲和素（streptavidin,SA）标记的传感器、生物素化的羊抗人IgE抗体、花生过敏患者血清池以及花生蛋白建立了一种测定花生蛋白与花生过敏患者血清IgE结合能力的新方法,优化检测条件为抗体1∶100稀释后线下固化20?min,血清1∶10稀释后过夜结合,完成传感器修饰。在线洗基线后用质量浓度为1?mg/mL的花生蛋白与传感器结合3?600?s,解离120?s。利用该法对不同热加工后花生蛋白与患者血清IgE的结合能力进行评估,并与常用的酶联免疫吸附实验（enzyme linked immunosorbent assay,ELISA）检测进行比较。结果表明,本方法可以直接评估过敏原蛋白与血清IgE的结合能力,与ELISA结果相关系数达到0.91。热加工中,油炸处理提高了花生蛋白的IgE结合能力,水煮和烘烤降低了花生蛋白的IgE结合能力,且去壳热加工比带壳热加工花生的蛋白的IgE结合能力更强。     

β-乳球蛋白IgE抗原决定簇的识别

以β- 乳球蛋白氨基酸序列为模板,错位合成β- 乳球蛋白多肽,以收集到的牛乳过敏患者血清为抗体,鉴定β- 乳球蛋白IgE 抗原决定簇,分析影响致敏性的关键氨基酸,探讨牛乳过敏机理。结果表明：β- 乳球蛋白IgE抗原决定簇有4 条,氨基酸序列分别为17～31、72～86、92～106、152～166,并且苏氨酸(AA20)、蛋氨酸(AA23)、天冬氨酸(AA27)是影响β- 乳球蛋白致敏性的关键氨基酸。说明特异性水解抗原决定簇或定点修饰氨基酸可以实现过敏原脱敏的目的。     

Serotonin Type 3 Receptors Modulate the Aggression-Stimulating Effects of Adolescent Cocaine Exposure in Syrian Hamsters (Mesocricetus auratus).

Repeated cocaine (0.5 mg/kg) exposure throughout adolescence stimulates offensive aggression in hamsters. These studies examined whether the cocaine-induced aggressive response was regulated by serotonin Type 3 (5-HT?) receptor activity and correlated with altered 5-HT? receptor expression. Cocaine-treated Syrian hamsters (Mesocricetus auratus) were tested for aggression after the administration of either the 5-HT? antagonist 3-tropanylindole-3-carboxylate methiodide (tropisetron; 0.01-1.20 mg/kg) or the 5-HT? agonist l-(m-chlorophenyl)-biguanide hydrochloride (mCPBG; 5.0-15.0 mg/kg), alone or in combination. Tropisetron alone dose dependently reduced cocaine-induced aggression, with a significant reduction at 0.3 mg/kg, whereas mCPBG was ineffective. mCPBG administered prior to tropisetron required a higher dose (1.2 mg/kg) of antagonist to block aggression, indicating a selective 5-HT? effect. Cocaine-treated hamsters showed altered 5-HT? immunoreactivity in several brain areas implicated in aggression control. These data support a role for 5-HT? receptors in adolescent cocaine-induced aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recent Advances in the Inhibition of the IL-4 Cytokine Pathway for the Treatment of Allergen-Induced Asthma

The IL-4 and IL-13 cytokine pathways play integral roles in stimulating IgE inflammation, with the IL-4 cytokine being a major cytokine in the etiology of thunderstorm asthma, atopic dermatitis, and allergic rhinitis. The increasing prevalence of thunderstorm asthma in the younger population and the lessening efficacy of corticosteroids and other anti-inflammatories has created a need for more effective pharmaceuticals. This review summarizes the IL-4 and IL-13 pathways while highlighting and discussing the current pathway inhibitors aimed at treating thunderstorm asthma and atopic dermatitis, as well as the potential efficacy of peptide therapeutics in this field.     

Co-Application with Tannic Acid Prevents Transdermal Sensitization to Ovalbumin in Mice

Transdermal sensitization to allergens is of great concern as a sensitization route for food allergies. This skin-mediated invasion and sensitization to allergens is involved in skin barrier breakdown and inflammation, followed by the production of several kinds of cytokines. Cytokines such as thymic stromal lymphopoietin and thymus and activation-regulated chemokine are also involved. In this study, we investigated the suppressive effect of tannic acid (TA) on transdermal sensitization using ovalbumin (OVA), a major egg-white allergen. We also analyzed the mechanisms associated with the inhibitory effects of TA. The results showed that the co-application with TA prevents transdermal sensitization to OVA. As possible mechanisms, its anti-inflammatory and astringent effect on the skin and binding ability with the protein were considered. These results indicate that TA could be applied to cosmetics and lotions, which could suppress the transdermal sensitization to allergens.