Api m 6: a new bee venom allergen

Processing Technologies for Bee Products: An Overview of Recent Developments and Perspectives

Increased demand for a more balanced, healthy, and safe diet has accelerated studies on natural bee products (including honey, bee bread, bee collected pollen royal jelly, propolis, beeswax, and bee venom) over the past decade. Advanced food processing techniques, such as ultrasonication and microwave and infrared (IR) irradiation, either has gained popularity as alternatives or combined with conventional processing techniques for diverse applications in apiculture products at laboratory or industrial scale. The processing techniques used for each bee products have comprehensively summarized in this review, including drying (traditional drying, infrared drying, microwave-assisted traditional drying or vacuum drying, and low temperature high velocity-assisted fluidized bed drying), storage, extraction, isolation, and identification; the assessment methods related to the quality control of bee products are also fully mentioned. The different processing techniques applied in bee products aim to provide more healthy active ingredients largely and effectively. Furthermore, improved the product quality with a shorter processing time and reduced operational cost are achieved using conventional or emerging processing techniques. This review will increase the positive ratings of the combined new processing techniques according to the needs of the bee products. The importance of the models for process optimization on a large scale is also emphasized in the future.

A Review of Honeybee Venom Allergens and Allergenicity

Honeybee venom is a source of proteins with allergenic properties which can result in in various symptoms, ranging from local reactions through to systematic life-threatening anaphylaxis, or even death. According to the World Allergy Organization (WAO), honeybee venom allergy is one of the most common causes of anaphylaxis. Among the proteins present in honeybee venom, 12 protein fractions were registered by the World Health Organization’s Allergen Nomenclature Sub-Committee (WHO/IUIS) as allergenic. Most of them are highly immunogenic glycoproteins that cross-react with IgE and, as a consequence, may give false positive results in allergy diagnosis. Allergenic fractions are different in terms of molecular weight and biological activity. Eight of these allergenic fractions have also been identified in honey. This explains frequent adverse reactions after consuming honey in people allergic to venom and sheds new light on the causes of allergic symptoms in some individuals after honey consumption. At the same time, it also indicates the possibility of using honey as a natural source of allergen in specific immunotherapy.

Bee Venom in Wound Healing

Bee venom (BV), also known as api-toxin, is widely used in the treatment of different inflammatory diseases such as rheumatoid arthritis or multiple sclerosis. It is also known that BV can improve the wound healing process. BV plays a crucial role in the modulation of the different phases of wound repair. It possesses anti-inflammatory, antioxidant, antifungal, antiviral, antimicrobial and analgesic properties, all of which have a positive impact on the wound healing process. The mentioned process consists of four phases, i.e., hemostasis, inflammation, proliferation and remodeling. The impaired wound healing process constitutes a significant problem especially in diabetic patients, due to hypoxia state. It had been found that BV accelerated the wound healing in diabetic patients as well as in laboratory animals by impairing the caspase-3, caspase-8 and caspase-9 activity. Moreover, the activity of BV in wound healing is associated with regulating the expression of transforming growth factor (TGF-β1), vascular endothelial growth factor and increased collagen type I. BV stimulates the proliferation and migration of human epidermal keratinocytes and fibroblasts. In combination with polyvinyl alcohol and chitosan, BV significantly accelerates the wound healing process, increasing the hydroxyproline and glutathione and lowering the IL-6 level in wound tissues. The effect of BV on the wounds has been proved by numerous studies, which revealed that BV in the wound healing process brings about a curative effect and could be applied as a new potential treatment for wound repair. However, therapy with bee venom may induce allergic reactions, so it is necessary to assess the existence of the patient’s hypersensitivity to apitoxin before treatment.

Antimicrobial Properties of Apis mellifera's Bee Venom

Bee venom (BV) is a rich source of secondary metabolites from honeybees (Apis mellifera L.). It contains a variety of bioactive ingredients including peptides, proteins, enzymes, and volatile metabolites. The compounds contribute to the venom’s observed biological functions as per its anti-inflammatory and anticancer effects. The antimicrobial action of BV has been shown in vitro and in vivo experiments against bacteria, viruses, and fungi. The synergistic therapeutic interactions of BV with antibiotics has been reported. The synergistic effect contributes to a decrease in the loading and maintenance dosage, a decrease in the side effects of chemotherapy, and a decrease in drug resistance. To our knowledge, there have been no reviews on the impact of BV and its antimicrobial constituents thus far. The purpose of this review is to address the antimicrobial properties of BV and its compounds.

P-ANCA vasculitis with diffuse alveolar haemorrhage preceded by a spider bite

We report a patient with antineutrophilic cytoplasmic antibody (ANCA) vasculitis that was preceded by witnessed black widow spider bites. The patient initially presented with a diffuse painful skin rash that developed after a few hours post bite. He was treated initially with topical ointment for the suspected bite. However, subsequently a few days later the patient returned to the hospital with similar, but more progressive rash with haemoptysis and acute hypoxic respiratory failure requiring supplemental oxygen. Immunology work up showed elevated titre of peri-nuclear ANCA. Bronchoscopy revealed diffuse alveolar haemorrhage. The patient was treated successfully with methylprednisolone and rituximab.

Bee Updated: Current Knowledge on Bee Venom and Bee Envenoming Therapy

Honey bees can be found all around the world and fulfill key pollination roles within their natural ecosystems, as well as in agriculture. Most species are typically docile, and most interactions between humans and bees are unproblematic, despite their ability to inject a complex venom into their victims as a defensive mechanism. Nevertheless, incidences of bee stings have been on the rise since the accidental release of Africanized bees to Brazil in 1956 and their subsequent spread across the Americas. These bee hybrids are more aggressive and are prone to attack, presenting a significant healthcare burden to the countries they have colonized. To date, treatment of such stings typically focuses on controlling potential allergic reactions, as no specific antivenoms against bee venom currently exist. Researchers have investigated the possibility of developing bee antivenoms, but this has been complicated by the very low immunogenicity of the key bee toxins, which fail to induce a strong antibody response in the immunized animals. However, with current cutting-edge technologies, such as phage display, alongside the rise of monoclonal antibody therapeutics, the development of a recombinant bee antivenom is achievable, and promising results towards this goal have been reported in recent years. Here, current knowledge on the venom biology of Africanized bees and current treatment options against bee envenoming are reviewed. Additionally, recent developments within next-generation bee antivenoms are presented and discussed.

Component-resolved diagnosis in hymenoptera allergy

Component-resolved diagnosis based on the use of well-defined, properly characterised and purified natural and recombinant allergens constitutes a new approach in the diagnosis of venom allergy. Prospective readers may benefit from an up-to-date review on the allergens. The best characterised venom is that of Apis mellifera, whose main allergens are phospholipase A2 (Api m1), hyaluronidase (Api m2) and melittin (Api m4). Additionally, in recent years, new allergens of Vespula vulgaris have been identified and include phospholipase A1 (Ves v1), hyaluronidase (Ves v2) and antigen 5 (Ves v5). Polistes species are becoming an increasing cause of allergy in Europe, although only few allergens have been identified in this venom. In this review, we evaluate the current knowledge about molecular diagnosis in hymenoptera venom allergy.

Component Resolved Diagnosis in Hymenoptera Anaphylaxis

PURPOSE OF REVIEW

Hymenoptera anaphylaxis is one of the leading causes of severe allergic reactions and can be fatal. Venom-specific immunotherapy (VIT) can prevent a life-threatening reaction; however, confirmation of an allergy to a Hymenoptera venom is a prerequisite before starting such a treatment. Component resolved diagnostics (CRD) have helped to better identify the responsible allergen.

RECENT FINDINGS

Many new insect venom allergens have been identified within the last few years. Commercially available recombinant allergens offer new diagnostic tools for detecting sensitivity to insect venoms. Additional added sensitivity to nearly 95% was introduced by spiking yellow jacket venom (YJV) extract with Ves v 5. The further value of CRD for sensitivity in YJV and honey bee venom (HBV) allergy is more controversially discussed. Recombinant allergens devoid of cross-reactive carbohydrate determinants often help to identify the culprit venom in patients with double sensitivity to YJV and HBV. CRD identified a group of patients with predominant Api m 10 sensitization, which may be less well protected by VIT, as some treatment extracts are lacking this allergen. The diagnostic gap of previously undetected Hymenoptera allergy has been decreased via production of recombinant allergens. Knowledge of analogies in interspecies proteins and cross-reactive carbohydrate determinants is necessary to distinguish relevant from irrelevant sensitizations.

Allergen-specific immunotherapy of Hymenoptera venom allergy - also a matter of diagnosis

Stings of hymenoptera can induce IgE-mediated hypersensitivity reactions in venom-allergic patients, ranging from local up to severe systemic reactions and even fatal anaphylaxis. Allergic patients' quality of life can be mainly improved by altering their immune response to tolerate the venoms by injecting increasing venom doses over years. This venom-specific immunotherapy is highly effective and well tolerated. However, component-resolved information about the venoms has increased in the last years. This knowledge is not only able to improve diagnostics as basis for an accurate therapy, but was additionally used to create tools which enable the analysis of therapeutic venom extracts on a molecular level. Therefore, during the last decade the detailed knowledge of the allergen composition of hymenoptera venoms has substantially improved diagnosis and therapy of venom allergy. This review focuses on state of the art diagnostic and therapeutic options as well as on novel directions trying to improve therapy.

Anti-fibrinolytic and anti-microbial activities of a serine protease inhibitor from honeybee (Apis cerana) venom

Bee venom contains a variety of peptide constituents, including low-molecular-weight protease inhibitors. While the putative low-molecular-weight serine protease inhibitor Api m 6 containing a trypsin inhibitor-like cysteine-rich domain was identified from honeybee (Apis mellifera) venom, no anti-fibrinolytic or anti-microbial roles for this inhibitor have been elucidated. In this study, we identified an Asiatic honeybee (A. cerana) venom serine protease inhibitor (AcVSPI) that was shown to act as a microbial serine protease inhibitor and plasmin inhibitor. AcVSPI was found to consist of a trypsin inhibitor-like domain that displays ten cysteine residues. Interestingly, the AcVSPI peptide sequence exhibited high similarity to the putative low-molecular-weight serine protease inhibitor Api m 6, which suggests that AcVSPI is an allergen Api m 6-like peptide. Recombinant AcVSPI was expressed in baculovirus-infected insect cells, and it demonstrated inhibitory activity against trypsin, but not chymotrypsin. Additionally, AcVSPI has inhibitory effects against plasmin and microbial serine proteases; however, it does not have any detectable inhibitory effects on thrombin or elastase. Consistent with these inhibitory effects, AcVSPI inhibited the plasmin-mediated degradation of fibrin to fibrin degradation products. AcVSPI also bound to bacterial and fungal surfaces and exhibited anti-microbial activity against fungi as well as gram-positive and gram-negative bacteria. These findings demonstrate the anti-fibrinolytic and anti-microbial roles of AcVSPI as a serine protease inhibitor.

Proteomics for Allergy: from Proteins to the Patients

Proteomics encompasses a variety of approaches unraveling both the structural features, post-translational modifications, and abundance of proteins. As of today, proteomic studies have shed light on the primary structure of about 850 allergens, enabling the design of microarrays for improved molecular diagnosis. Proteomic methods including mass spectrometry allow as well to investigate protein-protein interactions, thus yielding precise information on critical epitopes on the surface of allergens. Mass spectrometry is now being applied to the unambiguous identification, characterization, and comprehensive quantification of allergens in a variety of matrices, as diverse as food samples and allergen immunotherapy drug products. As such, it represents a method of choice for quality testing of allergen immunotherapy products.

IgE cross-reactivity of phospholipase A2 and hyaluronidase of Apis dorsata (Giant Asian Honeybee) and Apis mellifera (Western Honeybee) venom: Possible use of A. mellifera venom for diagnosis of patients allergic to A. dorsata venom

Diagnostic and therapeutic reagents are unavailable for anaphylaxis arising from stings by Apis dorsata. Venom profiles and cross-reactivity of A. dorsata and Apis mellifera were compared, to ascertain whether venom of A. mellifera can be used for diagnosis in A. dorsata allergy. Both venom profiles were similar by High Performance Liquid Chromatography and SDS-PAGE. Sera of 29 of 30 (96.7%) patients with anaphylaxis to A. dorsata stings had IgE to the phospholipase-2 (PLA₂) doublet (15 and 16 kDa) of A. dorsata venom by immunoblot, compared to 26 of 30 (86.7%) with the PLA₂ of A. mellifera and a purified preparation of PLA₂. Twelve patients (40%) with severe anaphylaxis had IgE reactivity to a 39 kDa protein band of venom of both species, a third band, identified in immunoblot as hyaluronidase. The cross-reactivity of PLA₂ and hyaluronidase of A. dorsata and A. mellifera were further confirmed by immunoblot inhibition results. Twenty five of 30 (83.3%) of our patients had positive venom specific IgE (>0.35 KU_A/L) reactivity to Phadia ImmunoCAPs of A. mellifera venom. The observed IgE cross reactivity suggests the possibility of using A. mellifera venom as a diagnostic test for A. dorsata venom allergy.

Anaphylaxis to insect venom allergens: role of molecular diagnostics

Anaphylaxis due to Hymenoptera stings is one of the most severe consequences of IgE-mediated hypersensitivity reactions. Although allergic reactions to Hymenoptera stings are often considered as a general model for the underlying principles of allergic disease, diagnostic tests are still hampered by a lack of specificity and venom immunotherapy by severe side effects and incomplete protection. In recent years, the knowledge about the molecular composition of Hymenoptera venoms has significantly increased and more and more recombinant venom allergens with advanced characteristics have become available for diagnostic measurement of specific IgE in venom-allergic patients. These recombinant venom allergens offer several promising possibilities for an improved diagnostic algorithm. Reviewed here are the current status, recent developments, and future perspectives of molecular diagnostics of venom allergy. Already to date, it is foreseeable that component-resolution already has now or will in the future have the potential to discriminate between clinically significant and irrelevant sensitization, to increase the specificity and sensitivity of diagnostics, to monitor immunotherapeutic intervention, and to contribute to the understanding of the immunological mechanisms elicited by insect venoms.

Genome-wide analysis of signatures of selection in populations of African honey bees (Apis mellifera) using new web-based tools

Background

With the development of inexpensive, high-throughput sequencing technologies, it has become feasible to examine questions related to population genetics and molecular evolution of non-model species in their ecological contexts on a genome-wide scale. Here, we employed a newly developed suite of integrated, web-based programs to examine population dynamics and signatures of selection across the genome using several well-established tests, including F_ST, pN/pS, and McDonald-Kreitman. We applied these techniques to study populations of honey bees (Apis mellifera) in East Africa. In Kenya, there are several described A. mellifera subspecies, which are thought to be localized to distinct ecological regions.

Results

We performed whole genome sequencing of 11 worker honey bees from apiaries distributed throughout Kenya and identified 3.6 million putative single-nucleotide polymorphisms. The dense coverage allowed us to apply several computational procedures to study population structure and the evolutionary relationships among the populations, and to detect signs of adaptive evolution across the genome. While there is considerable gene flow among the sampled populations, there are clear distinctions between populations from the northern desert region and those from the temperate, savannah region. We identified several genes showing population genetic patterns consistent with positive selection within African bee populations, and between these populations and European A. mellifera or Asian Apis florea.

Conclusions

These results lay the groundwork for future studies of adaptive ecological evolution in honey bees, and demonstrate the use of new, freely available web-based tools and workflows (http://usegalaxy.org/r/kenyanbee) that can be applied to any model system with genomic information.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1712-0) contains supplementary material, which is available to authorized users.

IgE recognition of chimeric isoforms of the honeybee (Apis mellifera) venom allergen Api m 10 evaluated by protein array technology

Api m 10 has recently been established as novel major allergen that is recognized by more than 60% of honeybee venom (HBV) allergic patients. Previous studies suggest Api m 10 protein heterogeneity which may have implications for diagnosis and immunotherapy of HBV allergy. In the present study, RT-PCR revealed the expression of at least nine additional Api m 10 transcript isoforms by the venom glands. Two distinct mechanisms are responsible for the generation of these isoforms: while the previously known variant 2 is produced by an alternative splicing event, novel identified isoforms are intragenic chimeric transcripts. To the best of our knowledge, this is the first report of the identification of chimeric transcripts generated by the honeybee. By a retrospective proteomic analysis we found evidence for the presence of several of these isoforms in the venom proteome. Additionally, we analyzed IgE reactivity to different isoforms by protein array technology using sera from HBV allergic patients, which revealed that IgE recognition of Api m 10 is both isoform- and patient-specific. While it was previously demonstrated that the majority of HBV allergic patients display IgE reactivity to variant 2, our study also shows that some patients lacking IgE antibodies for variant 2 display IgE reactivity to two of the novel identified Api m 10 variants, i.e. variants 3 and 4.

Reactions to honeybee stings: an allergic prospective

PURPOSE OF REVIEW

The purpose of this article is to provide a brief overview of the events involved in honeybee allergy and to concisely update the reader on progress toward knowledge of honeybee venom (HBV), strides in solving diagnostic difficulties, and advancements in improving safety and efficacy of HBV immunotherapy.

RECENT FINDINGS

It is well known that honeybee allergy is unique in venom allergen and protein composition, diagnostic challenges, and immunotherapy safety and efficacy. Many new honeybee allergens have been recognized. Advances in testing, evaluation, and extract manipulation methods, many using recombinant technology, have allowed a greater ability to help with honeybee allergy diagnosis and resultant improvement in immunotherapy safety and evaluation of immunotherapy efficacy.

SUMMARY

In an effort to address many honeybee allergy concerns, specific advances have been recently made. Some recently characterized honeybee allergens appear to be major contributors to honeybee allergy. In the setting of double-positivity, cross-reacting carbohydrate determinants and other cross-reacting components in HBV have made diagnosis of honeybee allergy challenging. Recombinant technology, including component-resolved diagnostics, and other evolving testing methods should help clarify double-positivity, if not now, in the very near future. Purified HBV and possibly depot formulations for immunotherapy appear to make it more well tolerated. Recombinant methods may help with evaluation of immunotherapy's safety and efficacy.

Proteome and phosphoproteome analysis of honeybee (Apis mellifera) venom collected from electrical stimulation and manual extraction of the venom gland

BACKGROUND

Honeybee venom is a complicated defensive toxin that has a wide range of pharmacologically active compounds. Some of these compounds are useful for human therapeutics. There are two major forms of honeybee venom used in pharmacological applications: manually (or reservoir disrupting) extracted glandular venom (GV), and venom extracted through the use of electrical stimulation (ESV). A proteome comparison of these two venom forms and an understanding of the phosphorylation status of ESV, are still very limited. Here, the proteomes of GV and ESV were compared using both gel-based and gel-free proteomics approaches and the phosphoproteome of ESV was determined through the use of TiO2 enrichment.

RESULTS

Of the 43 proteins identified in GV, < 40% were venom toxins, and >60% of the proteins were non-toxic proteins resulting from contamination by gland tissue damage during extraction and bee death. Of the 17 proteins identified in ESV, 14 proteins (>80%) were venom toxic proteins and most of them were found in higher abundance than in GV. Moreover, two novel proteins (dehydrogenase/reductase SDR family member 11-like and histone H2B.3-like) and three novel phosphorylation sites (icarapin (S43), phospholipase A-2 (T145), and apamin (T23)) were identified.

CONCLUSIONS

Our data demonstrate that venom extracted manually is different from venom extracted using ESV, and these differences may be important in their use as pharmacological agents. ESV may be more efficient than GV as a potential pharmacological source because of its higher venom protein content, production efficiency, and without the need to kill honeybee. The three newly identified phosphorylated venom proteins in ESV may elicit a different immune response through the specific recognition of antigenic determinants. The two novel venom proteins extend our proteome coverage of honeybee venom.

The major royal jelly proteins 8 and 9 (Api m 11) are glycosylated components of Apis mellifera venom with allergenic potential beyond carbohydrate-based reactivity

BACKGROUND

As hymenoptera venoms are one of the allergen sources causing the highest incidence of anaphylaxis and sometimes fatal consequences, the detailed characterization of all venom allergens is imperative for design of component-resolved diagnostic approaches and improved intervention strategies.

OBJECTIVE

Our aim was the immunochemical characterization of major royal jelly proteins (MRJP) 8 and 9, both components identified in honeybee venom (HBV) and putative allergens.

METHODS

Both MRJPs were recombinantly produced as soluble differentially glycosylated proteins providing a defined degree of reactivity to cross-reactive carbohydrate determinants (CCD) in insect cells. Allergen-specific IgE(sIgE) reactivity of HBV-allergic patients was analysed by ELISA and immunoblotting.

RESULTS

MRJP8 and MRJP9 were identified as venom components by MS-based proteomic analyses. In a population of 47 HBV-allergic patients, reactivities with CCD-carrying MRJPs were in the range of 56% (61%), underlining the contribution of CCDs to allergen-binding. Beyond CCD-reactivity, 15% of patients showed sIgE reactivity with MRJP8 and 34% with MRJP9 respectively. These reactivities roughly in the range of Api m 2 render the MRJPs minor, but important allergens.

CONCLUSION AND CLINICAL RELEVANCE

The glycosylated MRJP8 and MRJP9 of HBV have IgE-sensitizing potential in HBV-allergic patients beyond CCD reactivity and have to be considered as allergens, which might be potentially important for a fraction of venom allergic patients. They are valuable tools to elucidate individual component-resolved reactivity profiles of venom allergic patients and to provide insights into the role of particular venom components. Due to their allergenic properties, MRJP8 and MRJP9 were designated as isoallergens Api m 11.0101 and Api m 11.0201 respectively.

Identification of a novel melittin isoform from Africanized Apis mellifera venom

Apis mellifera, the European honey bee, is perhaps the most studied insect in the Apidae family. Its venom is comprised basically of melittin, phospholipase A(2), histamine, hyaluronidase, cathecolamines and serotonin. Some of these components have been associated to allergic reactions, among several other symptoms. On the other hand, bee mass-stinging is increasingly becoming a serious public health issue; therefore, the development of efficient serum-therapies has become necessary, with a consequent better characterization of the venom. In this work, we report the isolation and biochemical characterization of melittin-S, an isoform of melittin comprising a Ser residue at the 10th position, from the venom of Africanized A. mellifera. This peptide demonstrated to be less hemolytic than melittin and to adopt a less organized secondary structure, as assessed by circular dichroism spectroscopy. Melittin-S venom contents varied seasonally, and the maximum secretion occurred during the (southern) winter months. Data on the variation of the honey bee venom composition are necessary to guide future immunological studies, aiming for the development of an efficient anti-serum against Africanized A. mellifera venom and, consequently, an effective treatment for the victims of mass-stinging.

The nociceptive and anti-nociceptive effects of bee venom injection and therapy: a double-edged sword

Bee venom injection as a therapy, like many other complementary and alternative medicine approaches, has been used for thousands of years to attempt to alleviate a range of diseases including arthritis. More recently, additional theraupeutic goals have been added to the list of diseases making this a critical time to evaluate the evidence for the beneficial and adverse effects of bee venom injection. Although reports of pain reduction (analgesic and antinociceptive) and anti-inflammatory effects of bee venom injection are accumulating in the literature, it is common knowledge that bee venom stings are painful and produce inflammation. In addition, a significant number of studies have been performed in the past decade highlighting that injection of bee venom and components of bee venom produce significant signs of pain or nociception, inflammation and many effects at multiple levels of immediate, acute and prolonged pain processes. This report reviews the extensive new data regarding the deleterious effects of bee venom injection in people and animals, our current understanding of the responsible underlying mechanisms and critical venom components, and provides a critical evaluation of reports of the beneficial effects of bee venom injection in people and animals and the proposed underlying mechanisms. Although further studies are required to make firm conclusions, therapeutic bee venom injection may be beneficial for some patients, but may also be harmful. This report highlights key patterns of results, critical shortcomings, and essential areas requiring further study.

Detection of honeybee venom in envenomed tissues by direct MALDI MSI

A new analytical approach using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) for the study of honeybee venom is shown. In vitro and in vivo models simulating the bee sting have been developed using live honeybees and, as the envenomation sites, pig ears and rat legs; MALDI MSI has been used to map, over time, the diffusion and distribution of three venom allergens (Api m 1, Api m 4, and Api m 6) and two venom toxins (apamine and mast cell degranulating peptide). In conjunction with other classical biochemical techniques and high resolution mass spectrometry (HRMS), structural data have been obtained that contribute to current understanding of honeybee venom composition. Initial data have also been obtained demonstrating the feasibility of mapping the organism's response to the sting. The opportunity to monitor venom diffusion and the organism's response at the same time might open new pathways for in vivo preclinical studies in designing and testing new venom immunotherapy (VIT).

Honeybee venom induces calcium-dependent but caspase-independent apoptotic cell death in human melanoma A2058 cells

Honeybee (Apis mellifera) venom (BV) has been reported to exhibit anticancer effects, but its mode of action at the cellular and molecular levels remains largely unknown. We found that honeybee venom induced apoptosis in human melanoma A2058 cells but not in normal skin fibroblast Detroit 551 cells. The BV-induced apoptosis was accompanied by generation of reactive oxygen species and alteration of mitochondrial membrane potential transition. Treatment with antioxidants significantly attenuated BV-induced apoptosis. Although caspase-2 and -3 were slightly activated by BV, inhibitors of caspase-2 and -3 could not block BV-induced apoptosis in A2058 cells. Data from immunostaining indicated that EndoG and AIF were translocated from mitochondria to the cytosol or nucleus, suggesting that BV induces apoptosis in A2058 cells via a caspase-independent pathway. In addition, cJun N-terminal kinases (JNK) and ERK were rapidly activated after a 5 min incubation with BV, while p38 and AKT were inactivated after 30 min administration of BV. Inhibition of JNK significantly attenuated BV-triggered apoptotic death. Moreover, BV induced a rapid and marked increase in cytosolic calcium ion. Incubation of cells under calcium-free conditions effectively diminished BV-induced apoptosis. Furthermore, when the calcium-free treatment was combined with ouabain, the recovery of cellular calcium fluctuation protected A2058 cells against BV-induced apoptosis. Finally, treatment of A2058 cells with melittin, the major component of BV, resulted in similar elevation of calcium levels and cell killing effects, suggesting that melittin is the major determinant in BV-triggered cell death. These observations provide a molecular explanation for the antiproliferative properties of BV, and suggest that this agent may be useful in treating melanoma.

Melittin, a major bioactive component of bee venom toxin, inhibits PDGF receptor beta-tyrosine phosphorylation and downstream intracellular signal transduction in rat aortic vascular smooth muscle cells

Studies previously reported that melittin, a major bioactive component of bee venom, inhibits vascular smooth muscle cell (VSMC) proliferation through suppression of nuclear factor (NF)-kappaB and Akt activation and through enhancement of proapoptotic protein expression. In this study, the effects of melittin were investigated on the tyrosine phosphorylation of platelet-derived growth factor (PDGF) beta receptor (Rbeta) and its downstream intracellular signal transduction. When combined with PDGF-Rbeta inhibitor, melittin exhibited a synergic inhibitory effect on PDGF-BB-induced rat aortic VSMC proliferation. In addition, melittin inhibited PDGF-Rbeta phosphorylation in a concentration-dependent manner. Accordingly, the downstream signal transduction of PDGF-Rbeta, such as ERK1/2, Akt, and PLCgamma1 phosphorylation, was also inhibited by melittin in the same manner. These findings suggest that, in addition to suppressing NF-kappaB activation, the antiproliferative effect of melittin in VSMC may be mediated, at least in part, by the inhibition of PDGF-Rbeta tyrosine phosphorylation and its downstream intracellular signal transduction.

Myrmecia pilosula (Jack Jumper) ant venom: identification of allergens and revised nomenclature

BACKGROUND

The 'Jack Jumper Ant' (JJA; Myrmecia pilosula species complex) is the major cause of ant sting anaphylaxis in Australia. Our aims were to determine the allergenicity of previously described venom peptides in their native forms, identify additional allergens and if necessary, update nomenclature used to describe the allergens according to International Union of Immunological Societies criteria.

METHODS

Various polyacrylamide gel electrophoresis methods were used to separate JJA venom. Gel resolved venom was Western-blotted and probed with individual sera taken from patients with a history of JJA sting anaphylaxis and immunoglobulin E radioallergosorbent test (IgE RAST) tracer uptakes of >1% to whole venom.

RESULTS

Of 67 available sera, 54 had RAST uptakes >1%. Thirteen IgE binding bands were identified using these sera. Pilosulin 3, [Ile(5)]pilosulin 1, and pilosulin 4.1 were recognized by 42 (78%), 18 (33%) and nine (17%) of the 54 sera that were tested. Immunoglobulin E-binding proteins with estimated molecular masses of 6.6, 22.8, 25.6, 30.4, 32.1, 34.4 and 89.8 kDa were each recognized by three or more individual sera. Two of these (25.6 and 89.8 kDa) were recognized by 46% and 37% of sera, respectively.

CONCLUSION

Nomenclature used to describe JJA venom allergens has been revised. Pilosulin 3 (Myr p 2) is the only major allergen, whilst [Ile(5)]pilosulin 1 (Myr p 1), and pilosulin 4.1 (Myr p 3) are minor allergens. There are an additional five IgE-binding proteins that require further characterization before they can be named as allergens. These findings provide a framework for standardizing venom extracts for diagnosis and immunotherapy.

Molecular cloning and expression of two new allergens from Anisakis simplex

The nematode Anisakis simplex is a marine parasite that causes allergy as well as anisakiasis. Although five Anisakis allergens have already been identified, immunoblotting studies suggested that unidentified allergens still exist. In this study, an expression cDNA library constructed from A. simplex was subjected to immunoscreening using an Anisakis-allergic patient serum, and two positive clones coding for allergens (named Ani s 5 and 6) were obtained. Ani s 5 (152 amino acid residues) is homologous with nematode proteins belonging to the SXP/RAL-2 protein family and Ani s 6 (84 amino acid residues) with serine protease inhibitors from various animals. Of the 28 patient sera examined, seven and five reacted to recombinant Ani s 5 and 6 expressed in Escherichia coli, respectively. By inhibition immunoblotting experiments using the recombinant allergens as inhibitors, natural Ani s 5 could be identified as a 15-kDa protein in the crude extract of A. simplex but natural Ani s 6 could not be identified probably due to its low expression. In conclusion, Ani s 5 and 6 are new allergens of A. simplex that are specific to some Anisakis-allergic patients.

Key regulators in bee venom-induced apoptosis are Bcl-2 and caspase-3 in human leukemic U937 cells through downregulation of ERK and Akt

Bee venom (BV) has been known to inhibit proliferation and induce apoptosis in cancer cells. However, the molecular mechanisms involved in BV-induced apoptosis are still uncharacterized in human leukemic cells. In the present study, we report that BV induces apoptosis in leukemic U937 cells through downregulation of ERK and Akt signal pathway. Furthermore, BV-induced apoptosis was accompanied by downregulation of Bcl-2, activation of caspase-3 and a subsequent poly(ADP-ribose)polymerase (PARP) cleavages. The induction of apoptosis also was accompanied by the downregulation of the inhibitor of apoptosis protein (IAP) family proteins. Caspase-3 inhibitor, z-DEVD-fmk, was significantly capable of restoring cell viability and BV-induced apoptosis through caspase-3 activation was significantly attenuated in Bcl-2-overexpressing cells. These results indicate that downregulation of Bcl-2 plays a major role in the initiation as an activator of a caspase-3 involved with BV-induced apoptosis. BV also triggered the activation of p38 MAPK and JNK, and downregulation of ERK and Akt. PD98059 (an inhibitor of ERK) or LY294002 (an inhibitor of Akt), but not an inhibitor of p38 MAPK and JNK, significantly decreased cell viability and increased lactate dehydrogenase (LDH) release. The results indicated that key regulators in BV-induced apoptosis are Bcl-2 and caspase-3 in human leukemic U937 cells through downregulation of the ERK and Akt signal pathway.

Genomic and transcriptional analysis of protein heterogeneity of the honeybee venom allergen Api m 6

Several components of honeybee venom are known to cause allergenic responses in humans and other vertebrates. One such component, the minor allergen Api m 6, has been known to show amino acid variation but the genetic mechanism for this variation is unknown. Here we show that Api m 6 is derived from a single locus, and that substantial protein-level variation has a simple genome-level cause, without the need to invoke multiple loci or alternatively spliced exons. Api m 6 sits near a misassembled section of the honeybee genome sequence, and we propose that a substantial number of indels at and near Api m 6 might be the root cause of this misassembly. We suggest that genes such as Api m 6 with coding-region or untranslated region indels might have had a strong effect on the assembly of this draft of the honeybee genome.

Hymenoptera venom allergens

Hymenoptera venoms each contain a variety of protein allergens. The major components have all been characterized, and most of the amino acid sequences are known. This article concentrates on the use of contemporary techniques including cloning, mass spectrometry and genomics in the characterization of venom allergens, and newer separation techniques for protein isolation. Examples of the use of these techniques with venom proteins are presented.

Diagnosis of Hymenoptera venom allergy

The purpose of diagnostic procedure is to classify a sting reaction by history, identify the underlying pathogenetic mechanism, and identify the offending insect. Diagnosis of Hymenoptera venom allergy thus forms the basis for the treatment. In the central and northern Europe vespid (mainly Vespula spp.) and honeybee stings are the most prevalent, whereas in the Mediterranean area stings from Polistes and Vespula are more frequent than honeybee stings; bumblebee stings are rare throughout Europe and more of an occupational hazard. Several major allergens, usually glycoproteins with a molecular weight of 10-50 kDa, have been identified in venoms of bees, vespids. and ants. The sequences and structures of the majority of venom allergens have been determined and several have been expressed in recombinant form. A particular problem in the field of cross-reactivity are specific immunoglobulin E (IgE) antibodies directed against carbohydrate epitopes, which may induce multiple positive test results (skin test, in vitro tests) of still unknown clinical significance. Venom hypersensitivity may be mediated by immunologic mechanisms (IgE-mediated or non-IgE-mediated venom allergy) but also by nonimmunologic mechanisms. Reactions to Hymenoptera stings are classified into normal local reactions, large local reactions, systemic toxic reactions, systemic anaphylactic reactions, and unusual reactions. For most venom-allergic patients an anaphylactic reaction after a sting is very traumatic event, resulting in an altered health-related quality of life. Risk factors influencing the outcome of an anaphylactic reaction include the time interval between stings, the number of stings, the severity of the preceding reaction, age, cardiovascular diseases and drug intake, insect type, elevated serum tryptase, and mastocytosis. Diagnostic tests should be carried out in all patients with a history of a systemic sting reaction to detect sensitization. They are not recommended in subjects with a history of large local reaction or no history of a systemic reaction. Testing comprises skin tests with Hymenoptera venoms and analysis of the serum for Hymenoptera venom-specific IgE. Stepwise skin testing with incremental venom concentrations is recommended. If diagnostic tests are negative they should be repeated several weeks later. Serum tryptase should be analyzed in patients with a history of a severe sting reaction.

Computational tools for the study of allergens

Allergy is a major cause of morbidity worldwide. The number of characterized allergens and related information is increasing rapidly creating demands for advanced information storage, retrieval and analysis. Bioinformatics provides useful tools for analysing allergens and these are complementary to traditional laboratory techniques for the study of allergens. Specific applications include structural analysis of allergens, identification of B- and T-cell epitopes, assessment of allergenicity and cross-reactivity, and genome analysis. In this paper, the most important bioinformatic tools and methods with relevance to the study of allergy have been reviewed.

Allergen databases

Allergies represent a significant medical and industrial problem. Molecular and clinical data on allergens are growing exponentially and in this article we have reviewed nine specialized allergen databases and identified data sources related to protein allergens contained in general purpose molecular databases. An analysis of allergens contained in public databases indicates a high level of redundancy of entries and a relatively low coverage of allergens by individual databases. From this analysis we identify current database needs for allergy research and, in particular, highlight the need for a centralized reference allergen database.

Patients with negative skin tests

PURPOSE OF REVIEW

The aim of this article is to present and discuss the clinical problem of systemic anaphylaxis to Hymenoptera venoms in patients without detectable immunoglobulin E, as it appears in recent literature. Reported at variable frequency in large series of patients undergoing evaluation, systemic anaphylaxis was previously considered to reflect lost sensitization or to involve non-immunoglobulin E mediated mechanisms. Sporadic case-reports drew attention to the fact that severe or even fatal reactions may occur in patients with negative skin tests.

RECENT FINDINGS

A breakthrough article by Golden et al., who performed deliberate stings on skin test negative venom anaphylaxis patients, demonstrated that clinical sensitivity was still present in a subset of these subjects and pointed out to the limitations of present diagnostic methods or reagents. New immunobiochemical methods and highly specific recombinant allergens--when all clinically relevant Hymenoptera venom allergens have been identified, cloned, sequenced and expressed in the proper system--are anticipated to increase the diagnostic yield. Non-specific mechanisms causing anaphylactoid reactions will probably explain some enigmatic, skin test negative radioallergosorbent test negative cases in the future. Occult mastocytosis, predisposing patients to anaphylactoid reactions, has been reported with increasing frequency among skin test negative patients. Lastly, other causes mimicking venom anaphylaxis may on rare occasions contribute to the problem.

SUMMARY

With the present understanding of venom allergy, the practising clinician is not infrequently faced with the dilemma of the skin test negative patient. Once other identifiable causes have been carefully ruled out, referral to a specialized center for deliberate sting-challenges appears in selected cases to be a medically appropriate and ethically justified management approach.

Diagnosis of Hymenoptera venom sensitivity

PURPOSE OF REVIEW

The objective of this review is to highlight recent advances in the preparation, documentation and performance of reagents and methods used in the diagnosis of Hymenoptera-venom-induced immediate-type hypersensitivity.

RECENT FINDINGS

The following potent allergens have been reported: (1) a low-molecular-weight honey-bee allergen (Api m 6) has been described; (2) venom allergens in the North American species of bumble-bee (Bombus pennsylvanicus) have been more fully characterized, with the focus on phospholipase A2; (3) the vespid venom Ves v 5 allergen has been structurally mapped to identify immunoglobulin-E-binding epitopes; (4) the possible role of carbohydrate antigen epitopes as a cause of cross-reactivity among honey-bee and vespid venom proteins has been reported; and (5) the venom of Pachycondyla chinensis, an ant found commonly in the Far East, has been described. The most significant reports during this period have focused on the less-than-ideal performance of the intradermal venom skin-test reagents. The issue of the patient that is positive for venom allergy history but negative for an intradermal venom skin test is raised, and it is suggested that there is a need for caution and the use of serology as a supplementary diagnostic test.

SUMMARY

The important issue this year is the reminder that intradermal skin tests may be negative in venom-allergic patients, possibly because of changes in the potency of the extracts. The clinical history should drive the diagnosis of insect-sting allergy. When negative confirmatory venom skin-test or serology results are considered to be inconsistent with a positive history, they should be repeated.

Diffuse alveolar haemorrhage: a rare reaction to insect sting

Insect stings and subsequent reactions are common occurrences, but life-threatening systemic reactions are rare. Herein, we describe the case of a young man who developed diffuse pulmonary haemorrhage following an insect sting. He had experienced urticarial reactions to insect stings previously. Diffuse pulmonary haemorrhage should be recognized as an uncommon manifestation of severe systemic reaction to insect sting.

Hymenoptera (apid and vespid) allergy: update in diagnosis and management

Allergic reactions to Hymenoptera stings range from large local reactions to life-threatening anaphylaxis. Over the last 20 years, significant progress has been made using venom extracts in the diagnosis and treatment of Hymenoptera allergy. Despite these advances, there is still room for improvement in increasing the sensitivity of venom allergen skin testing. The venom allergic patient with negative skin tests poses special problems in management. It is important to note their increased risk with a subsequent sting. Guidelines to be used in determining the duration of venom immunotherapy are still evolving. Knowledge of the risks of discontinuing venom immunotherapy and risk factors associated with anaphylaxis with subsequent stings are required to form an individualized approach to treatment.