Histamine binding activity of surface-modified yeast by histamine binding protein (HBP)

Histamine is an immune mediator that is mainly secreted when an immediate, rapid response is needed in the body, and an excessive secretion of histamine or lack of enzymes that degrade histamine can result in various side effects. Histamine binding protein (HBP) is secreted by a mite species to prevent the host’s histamine-induced immune responses by binding the histamine molecule in the blood. Cloning was performed to express HBP on the yeast surface (MBTL-GWL-1), and immunofluorescence (IF) and western blot was performed to confirm the expression of the recombinant protein. The histamine inhibitory ability of GWL-1 cells was tested according to the cell concentration. The highest inhibitory ability of 1.30 × 107 CFU/ml of GWL-1 cells was of about 60 %. The GWL-1 cell concentration and the degree of histamine inhibition were confirmed to be dose-dependent, and dead cell debris was shown to have a histamine inhibitory effect, although not as much as that of whole cells. Phagocytosis assays were performed to determine whether histamine affected the RAW 264.7 cell’s phagocytosis, and to indirectly confirm the GWL-1 cell’s histamine inhibition. By confirming that, we found that GWL-1 captures histamine. Therefore, it can be expected to become a competitive material in the anti-allergy market.

Histamine Binding Activity of Surface-Modified Yeast by Histamine Binding Protein (HBP)

Histamine is an immune mediator that is mainly secreted when an immediate, rapid response is needed in the body, and an excessive secretion of histamine or lack of enzymes that degrade histamine can result in various side effects. Histamine binding protein (HBP) is secreted by a mite species to prevent the host’s histamine-induced immune responses by binding the histamine molecule in the blood. Cloning was performed to express HBP on the yeast surface (MBTL-GWL-1), and immunofluorescence (IF) and western blot was performed to confirm the expression of the recombinant protein. The histamine inhibitory ability of GWL-1 cells was tested according to the cell concentration. The highest inhibitory ability of 1.30×107 CFU/ml of GWL-1 cells was of about 60%. The GWL-1 cell concentration and the degree of histamine inhibition were confirmed to be dose-dependent, and dead cell debris was shown to have a histamine inhibitory effect, although not as much as that of whole cells. Phagocytosis assays were performed to determine whether histamine affected the RAW 264.7 cell’s phagocytosis, and to indirectly confirm the GWL-1 cell’s histamine inhibition. By confirming that, we found that GWL-1 captures histamine. Therefore, it can be expected to become a competitive material in the anti-allergy market.

Characterization of the Rhipicephalus (Boophilus) microplus Sialotranscriptome Profile in Response to Theileria equi Infection

This study intends to characterize the sialotranscriptome profile of Rhipicephalus (Boophilus) microplus in response to Theileria equi and identify genes of interest with differential genomic expression, indicating relevant targets in the tick–protozoan interactions. The experimental design consisted of RNA sequencing from uninfected and T. equi-infected R. microplus salivary glands (SGs) to obtain transcriptomic profiles for characterization and comparison. A total of 288,952 transcripts were obtained from both tick profiles, 3456 transcripts (p < 0.05) differentially expressed in response to T. equi infection. The uninfected SGs’ registered 231,179 transcripts, of which 155,359 were annotated. The most transcribed sequences were female-specific histamine binding protein and lipocalins. Regarding the T. equi-infected SGs, from the 238,964 assembled transcripts, 163,564 were annotated. The most transcribed sequences were histone demethylase JARID1 and Y-box-binding protein. Five transcripts (cystatin, arginase, nuclear factor κB kinase inhibitor subunit β (IκB), IκB delta, lysosomal-trafficking regulator, and reeler protein) presented the gene ontology (GO) category “response to protozoan” and were exclusively displayed in the T. equi-infected profile. The transcriptome of T. equi was also analyzed, registering 4728 hits. The study’s genetic and molecular information would be of great value for future studies and biotechnological applications envisaging disease control.

Lactic acid bacterial exopolysaccharides strongly bind histamine and can potentially be used to remove histamine contamination in food

The symptoms of foodborne histamine poisoning are similar to those of IgE-mediated food allergies. In this study, we investigated the histamine-binding capacity of lactic acid bacteria (LAB) strains as potential preventive agents against histamine poisoning. Histamine biosorption capacity was determined for 16 LAB strains. Leuconostoc mesenteroides TOKAI 51 m, Lactobacillus paracasei TOKAI 65 m, Lactobacillus plantarum TOKAI 111 m and Pediococcus pentosaceus TOKAI 759 m showed especially high biosorption rates and reached saturation within 30 min. Adsorption isotherms showed better conformance to the Freundlich model than to the Langmuir model. Analyses after heat, periodic acid and guanidine hydrochloride treatments suggested that histamine was bound to the bacterial cell surface. HPLC analysis revealed that exopolysaccharides produced by Lact. paracasei TOKAI 65 m strongly bound to histamine. In the detachment test with 1 mol l−1 HCl solution, the dissociation rate of histamine for Lact. paracasei TOKAI 65 m was <10 %. This strain is presumably a suitable candidate for use against histamine poisoning.

Development of a histamine aptasensor for food safety monitoring

Histamine produced by bacteria through decarboxylation of histidine in spoiled foods such as fish is known to cause food poisoning. Therefore, accurate and facile measurement of histamine is of practical importance. Using the recently discovered RNA aptamer that specifically recognizes histamine (A1-949 aptamer), we developed an aptasensor based on the structure-switching mechanism. Specifically, the aptamer A1-949 was fluorescently labeled at the 5′ end and hybridized with a short quencher DNA strand that is partially complementary to the aptamer. The quencher strand was modified with a fluorescence quencher at its 3′ terminus. Displacement of the quencher strand upon histamine binding results in an increased fluorescence. After optimizing the assay condition, the enantiomeric version of the aptasensor (L-RNA and L-DNA) was synthesized which could detect the achiral analyte with identical sensitivity and improved biochemical stability. The aptasensor performance was validated by measuring fish samples spiked with known concentrations of histamine. Finally, histamine content in spoiled fish samples was measured, and the results were compared with the measurements using a commercial enzymatic assay kit.

Natural Cuban zeolites for medical use and their histamine binding capacity

The work reported herein involves the characterization of natural zeolites from two different mines (San Andrés and Tasajeras; Cuba) using XRD, SEM, TG-DTA, ICP and surface area measurements. In addition, the chemical composition of zeolites, the heavy metal and environmental organic toxins content, the ion exchange rates, stability under biological conditions using simulated body fluids as well as the binding capacity for histamine have been investigated with a view to using them as medical products. The investigated zeolites contain clinoptilolite and mordenite as major phases. Furthermore, the samples are apparently free from fibrous materials according to SEM observations. In particular, the San Andrés zeolite binds remarkable amounts of histamine which are nearly irreversible under acidic (pH = 1; 12.4 mg/g) and neutral conditions (pH = 7; 15.7 mg/g), respectively. Thus, the San Andrés sample may well be applied as a medical product due to its excellent binding capacity for histamine along with its remaining optimum physico-chemical characteristics.