Effects of Glycosylation Combined with Phosphate Treatment on the Allergenicity and Structure of Tropomyosin in Litopenaeus vannamei.

Tropomyosin (TM) is the main allergen in shrimp (Litopenaeus vannamei). In this study, the effects of allergenicity and structure of TM by glycosylation (GOS-TM), phosphate treatment (SP-TM), and glycosylation combined with phosphate treatment (GOS-SP-TM) were investigated. Compared to GOS-TM and SP-TM, the IgG/IgE binding capacity of GOS-SP-TM was significantly decreased with 63.9 ± 2.0 and 49.7 ± 2.7%, respectively. Meanwhile, the α-helix content reduced, surface hydrophobicity increased, and 10 specific amino acids (K30, K38, S39, K48, K66, K74, K128, K161, S210, and K251) were modified by glycosylation on six IgE linear epitopes of GOS-SP-TM. In the BALB/c mice allergy model, GOS-SP-TM could significantly reduce the levels of specific IgE, IgG1, and CD4+IL-4+, while the levels of IgG2a, CD4+CD25+Foxp3+, and CD4+IFN-γ+ were increased, which equilibrated Th1 and Th2 cells, thus alleviating allergic symptoms. These results indicated that glycosylation combined with phosphate treatment can provide a new insight into developing hypoallergenic shrimp food.

Optimized carbonylation treatment of Litopenaeus vannamei matrix decreased its immunoreactivity and improved edible quality, simultaneously.

The study aimed to investigate how carbonylation affects the immunoreactivity and edible quality of the Litopenaeus vannamei matrix. The carbonylation treatment conditions of the shrimp matrix were optimized. Firstly, the treatment condition is optimized with 1.0 mmol/L malonaldehyde at 37 °C, 12 h. The optimized carbonylated shrimp showed lower immunoreactivity, carbonyl group, and free amino acids. Then the edible quality was evaluated, optimized carbonylated shrimp matrix presented better digestibility and the continuous digestion products showed lower immunoreactivity. Optimized carbonylated shrimp for the other sensory indicators showed better texture properties and an inviting appearance. Looser microstructure by scanning electron microscopy contributed to the higher digestibility, lower immunoreactivity, and better edible quality for optimized carbonylated shrimp matrix. Besides, more potentially modified amino acid residues exposed on the allergen surface may be the other reason. In conclusion, optimized carbonylation treatment reduced the immunoreactivity and improved the edible quality of shrimp.

IgE Epitope Analysis and Hypo-Immunoreactivity Derivative of Arginine Kinase in Mantis Shrimp (Oratosquilla oratoria).

As the main allergenic food, shrimp can trigger allergic reactions in various degrees. In this study, arginine kinase (AK) was identified as an allergen in Oratosquilla oratoria by LC-MS/MS. The open reading frame of AK was obtained, which included 356 amino acids, and recombinant AK (rAK) was expressed in Escherichia coli. The results of immunological analysis and circular dichroism showed that rAK displayed similar IgG-/IgE-binding activity and structure as native AK. Besides, five IgE linear epitopes of AK were verified by serological analysis, on the basis of which an epitope-deleted derivative was obtained and named as mAK-L. It has been shown that mAK-L displayed hypo-immunoreactivity compared to rAK, and the contents of secondary structures were different. In conclusion, these discoveries enrich the overall understanding of crustacean allergens and epitopes and set the foundations for food allergy diagnosis and immunotherapy.

Immunoglobulin E Epitope Mapping and Structure-Allergenicity Relationship Analysis of Crab Allergen Scy p 9.

Filamin C is an allergen of Scylla paramamosain (Scy p 9), and six IgE linear epitopes of the allergenic predominant region had previously been validated. However, the IgE epitope and structure-allergenicity relationship of Scy p 9 are unclear. In this study, a hydrophobic bond was found to be an important factor of conformation maintaining. The critical amino acids in the six predicted conformational epitopes were mutated, and the IgE-binding capacity and surface hydrophobicity of four mutants (E216A, T270A, Y699A, and V704A) were reduced compared to Scy p 9. Ten linear epitopes were verified with synthetic peptides, among which L-AA187-205 had the strongest IgE-binding capacity. In addition, IgE epitopes were mapped in the protruding surface of the tertiary structure, which were conducive to binding with IgE and exhibited high conservation among filamin genes. Overall, these data provided a basis for IgE epitope mapping and structure-allergenicity relationship of Scy p 9.

Characterization, Epitope Identification, and Cross-reactivity Analysis of Tropomyosin: An Important Allergen of Crassostrea angulata.

Oyster is a common shellfish product in China, which is associated with food allergy. However, there is still lack of research on allergens in oysters. In this study, tropomyosin (TM), an important allergen of Crassostrea angulata, was purified and identified by mass spectrometry. Subsequently, TM was cloned and expressed, with a sequence of size 852 bp, encoding 284 amino acid residues. The results of circular dichroism, digestion assay, inhibition enzyme-linked immunosorbent assay, and basophil activation test showed that recombinant TM had similar physicochemical properties and immunological properties to native TM. Furthermore, two conformational mimotopes were obtained and 10 IgE linear epitopes were verified. Meanwhile, different degrees of cross-reactivity were observed between C. angulata TM and the other 8 shellfish TMs using antibodies and serological analysis, which may relate to the 3 conserved epitope regions. These findings are expected to provide a theoretical basis for the molecular diagnosis of oyster allergy and cross-reactivity among shellfish.

Crystal Structure Analysis and IgE Epitope Mapping of Allergic Predominant Region in Scylla paramamosain Filamin C, Scy p 9.

Filamin C (FLN c) is a novel allergen in shellfish. In this study, FLN c from Scylla paramamosain was divided into three regions for recombinant expression based on the number of domains and amino acids. Using dot blot and basophil activation tests, the allergic predominant region of FLN c was determined to be 336-531 amino acid positions (named FLN c-M). It was confirmed that by X-ray diffraction, the crystal structure of FLN c-M with immunoglobulin-like folding at a resolution of 1.7 Å was obtained. The monomer was a barrel structure composed of 16 ß-strands and 2 α-helices. Three conformational epitopes were predicted, six linear epitopes were verified by serological test, and they were positioned on the crystal structure of FLN c-M. For the first time, the crystal structure of the allergic predominant region of FLN c was determined, and it provided an accurate template for the localization of IgE epitopes.

Identification of linear epitopes and their major role in the immunoglobulin E-binding capacity of tropomyosin from Alectryonella plicatula.

Tropomyosin (TM) is an important allergen in molluscans. However, there was a lack of information about TM as an allergen in oysters. TM was purified and identified from Alectryonella plicatula (ATM), and its primary sequence was cloned and encoded with 284 amino acids (AAs). Chemical denaturants were used to destroy the structure to confirm that linear epitopes played a major role in the immunoglobulin E-binding capacity of ATM. Subsequently, nine linear epitopes were identified using a serological test. The peptide with AA27-41 was regarded as the key epitope because it could be recognized strongly by most sera of oyster-sensitive individuals in comparison to other epitope peptides. Finally, the epitopes and the primary sequence of TM among shellfish were aligned to find the two conserved epitopes (AA117-132 and AA164-178) in oyster, octopus, abalone, scallop, clam, shrimp, and crab. Overall, these data provide a foundation for the allergenicity and cross-reactivity of TM.

Hypoallergenic derivatives of Scylla paramamosain heat-stable allergens alleviated food allergy symptoms in Balb/c mice.

The design of hypoallergenic derivatives is a new strategy for allergen-specific immunotherapy. Although hypoallergenic derivatives of Scylla paramamosain (mud crab) heat-stable tropomyosin (TM) and myosin light chain (MLC) have been preliminarily explored, their allergenicity in vivo needs to be further studied. In this work, recombinant allergens (wtTM, wtMLC) and hypoallergenic derivatives (mtTM, mtMLC) were purified. IgE-binding frequencies of wtTM and wtMLC in 177 crab-sensitised patients were 32.8% and 11.9%, respectively. In the Balb/c mouse model, mtTM and mtMLC caused mild intestinal inflammation, did not activate T-helper (Th) 2 immune response (interleukin-4, anaphylactic mediator, IgE, and IgG1 antibodies were not significantly increased) but could significantly promote the production of interleukin-10, which equilibrated Th1/Th2 cells, thus alleviating allergic symptoms. Moreover, mtTM and mtMLC-induced rabbit/mice anti-IgG antibodies could effectively block wtTM and wtMLC binding to patients' sera IgE in vitro. These results indicate that hypoallergenic derivatives offer the promise for an immunotherapeutic regimen for crab allergy.

IgE Epitope Analysis for Scy p 1 and Scy p 3, the Heat-Stable Myofibrillar Allergens in Mud Crab.

Tropomyosin (Scy p 1) and myosin light chain (Scy p 3) are investigated to be important heat-stable allergens in Scylla paramamosain. However, the epitopes of Scy p 1 and Scy p 3 are limited. In this study, recombinant Scy p 1 and Scy p 3 had similar IgE-binding capacity to natural proteins. Mimotopes of Scy p 1 and Scy p 3 were analyzed by bioinformatics, phage display, and one-bead-one-compound technology. Ten linear epitopes of Scy p 1 and seven linear epitopes of Scy p 3 were identified by synthetic peptides and inhibition dot blot. Meanwhile, three conformational epitopes of Scy p 1 and seven conformational epitopes of Scy p 3 were verified by site-directed mutagenesis and the serological test. Furthermore, strong IgE-binding epitopes of Scy p 1 and Scy p 3 were conserved in multiple crustaceans. Overall, these epitopes could enhance our understanding of crab allergens, which lay the foundation for a cross-reaction.

Combination Processing Method Reduced IgE-Binding Activity of Litopenaeus vannamei by Modifying Lysine, Arginine, and Cysteine on Multiple Allergen Epitopes.

Allergic reactions occur after the whole food is ingested, rather than the purified allergen. The present study explores the low-allergenic food processing for Litopenaeus vannamei by analysis of macrostructure, digestibility, and immunoreactivity. Furthermore, the presence of modified amino acids on the reported IgE epitopes was analyzed by mass spectrometry. Results showed that the combination processing of Maillard reaction (shrimp meat with galactose) with high temperature-pressure at 115 °C obviously changed the macrostructure and increased the digestibility for the shrimp meat. Meanwhile, the processing significantly reduced the IgG/IgE-binding activity of the shrimp meat. The hypo-IgE-binding activity in processed shrimp may be due to the modification of lysine, arginine, and cysteine residues in antigen epitopes. This is a comprehensive assessment of the specific amino acid residues modified by glycation of multiple allergens in processed L. vannamei, which provides a new research method to explore the hypo-IgE-binding activity in food.

IgE epitope analysis of sarcoplasmic-calcium-binding protein, a heat-resistant allergen in Crassostrea angulata.

Sarcoplasmic-calcium-binding protein (SCP) has been investigated as a novel allergen in Crassostrea angulata. Nevertheless, knowledge of its effector-cell-based allergic relevance and epitopes is limited. In this study, the heat-resistant allergen SCP was able to induce significant upregulation of CD63 and CD203c (p < 0.05), which showed obvious allergenicity in a basophil activation test. Furthermore, immunoinformatic tools, a one-bead-one-compound peptide library, and phage display technology were combined to analyze the allergenic epitopes of SCP. Five linear epitopes named L-SCP-1 (AA22-33), L-SCP-2 (AA64-75), L-SCP-3 (AA80-90), L-SCP-4 (AA107-116), and L-SCP-5 (AA144-159) were verified using serological tests. Additionally, two conformational epitopes (C-SCP-1 and C-SCP-2) were determined, and C-SCP-1 was located at one of the calcium-binding sites (AA106-117). Moreover, SCP showed weaker typical α-helical features and higher hydrophobicity after Ca2+ depletion, which reduced its IgE-binding capacity. Overall, these epitope data could enhance our understanding of oyster allergens, which could be used to develop hypoallergenic shellfish products.

Linear Epitopes Play an Important Role in the Immunoglobulin G (IgG)/Immunoglobulin E (IgE)-Binding Capacity of Scy p 4.

Sarcoplasmic calcium-binding protein is a stable allergen in Scylla paramamosain and named Scy p 4. To explore the importance of linear epitopes in the immunoglobulin G (IgG)/immunoglobulin E (IgE)-binding capacity of Scy p 4, chemical denaturants were used to destroy the structure. Scy p 4 was reduced with dithiothreitol and subsequently alkylated with iodoacetamide (IAA). Furthermore, the structural analysis indicated that IAA-Scy p 4 was an unstructured protein. The inhibition enzyme-linked immunosorbent assay showed that IAA-Scy p 4 could inhibit the binding of Scy p 4 to sensitize serum, with inhibition rates reached 55%. Moreover, the linear mimotopes of Scy p 4 were predicted in silico. Three linear epitopes were verified by serological tests and named L-Scy p 4-1 (AA76-91), L-Scy p 4-2 (AA111-125), and L-Scy p 4-3 (AA137-146). Overall, these data provide an understanding of the relationship between the structure and allergenicity about Scy p 4, and the identified linear epitopes can be used for diagnosis and food processing of shellfish allergy.

Effects of thermal processing on the allergenicity, structure, and critical epitope amino acids of crab tropomyosin.

Food processing can change the structure and immunoreactivity of purified allergens, but the effect of food processing on the immunoreactivity of the processed and purified allergen is still poorly understood. In this study, tropomyosin (TM) was obtained from Scylla paramamosain and purified after different treatments. A basophil activation test was employed to detect the allergenicity of allergens. The protein structure was detected by mass spectrometry, circular dichroism spectroscopy and surface hydrophobicity. Critical amino acids were identified by Dot blot. Heating obviously affects the biochemical characteristics of TM. The allergenicity of TM was decreased in high temperature-pressure-processed crabs, due to alteration in the protein structure (e.g. denaturation). Seven critical amino acids, namely, R21, E103, E104, E115, A116, E122 and E156, related to the maintenance of the IgE-binding activity of TM were identified. This research of thermal processing helps to accurately reduce or eliminate the immunoreactivity of crabs by food processing.

Cloning, expression and comparison of the properties of Scy p 9, a Scylla paramamosain allergen.

This study investigated the properties of Scy p 9 in mud crab (Scylla paramamosain). The gene sequence of filamin C obtained from crabs, which was denoted as Scy p 9, contains a 2544 bp open reading frame and encodes 848 amino acid residues. Recombinant Scy p 9 (rScy p 9) is expressed in Escherichia coli, which exhibits tertiary structure changes, and the IgE binding activity of rScy p 9 is higher than that of native Scy p 9 (nScy p 9). Moreover, this study explored the possibility of the presence and cross-reactivity of filamin C in 8 shellfish. IgE-specific binding to nScy p 9 and rScy p 9 in patients allergic to shellfish revealed that rScy p 9 was more sensitive than nScy p 9. The gene sequence of filamin C fills in the blank in shellfish. This study contributes to the understanding of the properties of Scy p 9, and the results indicate that rScy p 9 can be used as a candidate for component-resolved diagnosis in shellfish.

Identification and Cross-reactivity Analysis of Sarcoplasmic-Calcium-Binding Protein: A Novel Allergen in Crassostrea angulata.

Oysters are an important shellfish group known to cause food allergy; however, knowledge of their sensitization components and cross-reactivity is limited. This study aimed to identify a novel allergen in Crassostrea angulata and investigate its cross-reactivity. To this end, a 20 kDa protein was purified from oyster and confirmed to be a sarcoplasmic-calcium-binding protein (SCP) by LC-MS/MS. A 537 bp open reading frame was obtained from oyster SCP total RNA, which encoded 179 amino acids, and was expressed in Escherichia coli. According to the circular dichroism results, digestion assay, and inhibition ELISA, the recombinant SCP (rSCP) exhibited similar physicochemical properties and IgG-binding activity to native SCP. rSCP displayed stronger IgE-binding activity by immunological method. Moreover, a different intensity of cross-reactivity and sequence homology were demonstrated between shellfish species. Collectively, these findings provide novel insight into shellfish allergens, which can be used to aid in the in vitro diagnosis of oyster-sensitized patients.

Delayed in toilet training association with pediatric lower urinary tract dysfunction: A systematic review and meta-analysis.

BACKGROUND: Globally, attitudes and practices towards toilet training have changed several decades ago and children are completing toilet training at a later age compared to previous generations. Concurrently, there has been an increase in the incidence of pediatric bladder bowel dysfunction (BBD), including lower urinary tract dysfunction (LUTD). Whether the fact of delayed toilet training may negatively impact the ability of children to obtain bladder and bowel control and cause LUT dysfunction remains controversial. OBJECTIVES: To investigate the association between age at initiation of toilet training or approach to toilet training and the risks of lower urinary tract (LUT) dysfunction. METHODS: A comprehensive search of the CENTRAL, EMBASE and MEDLINE via Ovid SP, and CINAHL via EBSCO databases was conducted to identify RCTs, cohort or case-control studies investigating the association between age at initiation of toilet training, approach used for toilet training, and pediatric LUT dysfunction. RESULTS: A total of 10 studies with 24,121 participants (aged 5-17) were included for pooled analysis. Overall, the odds ratio (OR) with 95% confidence interval (95%CI) of LUT dysfunction in children who initiated toilet training at a younger age when compared to those who initiated toilet training at an older age, was 0.71 (0.63-0.81), P < 0.001), irrespective of the approach used for toilet training (Table). Subgroup analysis for day-time incontinence (persistent daytime wetting) was 0.77 (0.62-0.95), P = 0.014; although the outcomes for enuresis fluctuated, favorable results were still observed in the earlier training group (OR:0.63, 95%CI:0.43-0.94, P = 0.023). Subgroup analysis for age at initiating toilet training vs LUT dysfunction also showed favorable results in children who were trained earlier, i.e., before 24 months (OR:0.77, 95% CI 0.63-0.94, P = 0.009). Sensitivity analysis confirmed that the results were robust. DISCUSSION: Although the definition about the age of initial toilet training varied greatly in studies, findings from the current study suggested that the optimal time for initiating toilet training may be prior to the age of 24 months; if toilet training was initiated after 24 months or later, it may result in increased prevalence of LUT dysfunction. Since no RCTs studies were included in the current meta-analysis, well-designed longitudinal studies with larger sample size and from different cultural background are needed to confirm these results. CONCLUSION: This meta-analysis presents preliminary findings that show the incidence of LUTD may be decreased by initiating toilet training in children at a younger age.

Effects of thermal processing on digestion stability and immunoreactivity of the Litopenaeus vannamei matrix.

Many types of shellfish, including shrimp, are sometimes cooked before ingestion. Hence, it is necessary to investigate how cooking (boiling, pressure treatment or none (raw)) affects the structure, digestibility and immunoreactivity of multi-component shrimp muscle. Protein extraction, simulated gastrointestinal digestion, immunoreactivity, immunoglobulin E (IgE)-mediated human mast cell degranulation, morphology, particle size and UV absorbance scanning were used to investigate changes in the shrimp muscle upon treatment. The extractability of proteins and allergens was highest with 0.5 mol L-1 NaCl. Pressure treatment increased the digestibility and reduced the immunoreactivity of shrimp edible portions. Thermal processing induced the production of regular fiber bundles, blue shifts of absorbance peaks and reduction of particle size in the complex food matrix. These changes in macro- and micro-structure can further affect gastrointestinal digestibility and immunoreactivity due to the interactions between multiple components in the whole food. In conclusion, the digestibility, immunoreactivity and structure were altered by thermal processing of the complex food matrix.

Cloning, Expression, and Epitope Identification of Myosin Light Chain 1: An Allergen in Mud Crab.

Mud crab (Scylla paramamosain) is a commonly consumed seafood as a result of its high nutritional value; however, it is associated with food allergy. The current understanding of crab allergens remains insufficient. In the present study, an 18 kDa protein was purified from crab muscle and confirmed to be myosin light chain 1 (MLC1) by matrix-assisted laser desorption/ionization-tandem time-of-flight mass spectrometry. Total RNA was isolated and amplified to obtain a MLC1 open reading frame of 462 bp, encoding 154 amino acids. A structural analysis revealed that recombinant MLC1 (rMLC1) expressed in Escherichia coli contained α-helix and random coil. Moreover, rMLC1 displayed strong immunoactivity by dot blot and a basophil activation test. Furthermore, seven allergenic epitopes of MLC1 were predicted, and five critical epitope regions were identified by an inhibition enzyme-linked immunosorbent assay and human mast cell degranulation assay. This comprehensive research of an allergen helps to conduct component-resolved diagnoses and immunotherapies related to crab allergies.

Crystal Structure Analysis and Conformational Epitope Mutation of Triosephosphate Isomerase, a Mud Crab Allergen.

The triosephosphate isomerase (TIM), Scy p 8, is a crab allergen and shows cross-reactivity in the shellfish. Here, recombinant Scy p 8 was expressed, and its crystal structure was determined at a resolution of 1.8 Å. The three-dimensional structure of Scy p 8 is primarily composed of a (ß/α)8-barrel motif prototype. Additionally, Scy p 8 showed cross-reactivity with high sequential and secondary structural identity among TIMs from shellfish species. The site-directed mutagenesis of critical amino acids of conformational epitopes was carried out, and the mutants of Trp 168 and Lys 237 to Ala reduced immunoglobulin E (IgE)-binding activity by approximately 30%, compared with wild-type TIM in an inhibition ELISA; however, it still induced basophil activation despite the interpatient variability between patients. These results can help to provide an accurate template for the analysis of the IgE binding and establish meaningful relationships between structure and allergenicity.

[Correlations of blood lead levels in infant, in maternal blood and in breast milk].

OBJECTIVE: To understand the correlation of blood lead levels in infant, in maternal blood and in breast milk as to providing evidence for prevention of potential infant hazard from lead. METHODS: Lead levels were measured by using graphite stove atom absorption spectrographic methods in maternal breast milk, maternal blood and infant blood in infants aged 0 to 11 months and their mothers between November and December 2002 in Xiamen City. Blood samples were collected from both mother and infant's fingertips. Questionnaires were also used to collect information about childbirth, mothers, families and other related environmental factors. RESULTS: All 177 infants and their mothers were enrolled in the study. Infant blood lead levels reached a range from 0.12 micromol/L to 1.36 micromol/L, with a geometric mean (GM) of 0.37 micromol/L. There were 46 infants (21.64%) having blood lead levels over 0.48 micromol/L. And the maternal blood lead levels ranged from 0.21 micromol/L to 2.38 micromol/L (GM = 0.50 micromol/L). Among the 177 infants, 160 (93.8%) were breastfed; breast milk was collected from 105 (63.3%) of these mothers. Infant blood lead level was significantly correlated with the levels of maternal blood lead and breast milk lead, which indicated that maternal blood lead level might influence the infant blood lead levels through the breast milk. Blood lead levels in infants living in old business district and the breast milk lead levels of their mothers were higher than those in any other areas (P < 0.01); partial correlation analysis showed that infant blood lead levels were positively associated with the maternal blood lead level, infant's age and mother's work, and negatively associated with mother's height. CONCLUSION: The infant blood lead levels should not only relate to the maternal blood lead and the breast milk lead levels, so regards should be had to the other environmental factors, when selecting the feeding pattern and family rearing behaviors.