The use of melittin to enhance transgene expression mediated by recombinant adeno-associated virus serotype 2 vectors both in vitro and in vivo / 中西医结合学报

OBJECTIVE@#Melittin, a cell-penetrating peptide, improves the efficiency of many non-viral gene delivery vectors, yet its application in viral vectors has not been well studied. The non-pathogenic recombinant adeno-associated virus (rAAV) vector is an ideal in vivo gene delivery vector. However, its full potential will only be achieved after improvement of its transduction efficiency. To improve the transduction efficiency of rAAV2 vectors, we attempted to develop a melittin-based rAAV2 vector delivery strategy.@*METHODS@#The melittin peptide was inserted into the rAAV2 capsid either in the loop VIII of all viral proteins (VPs) or at the N terminus of VP2. Various rAAV2-gfp or -fluc vectors were subjected to quantitative real-time polymerase chain reaction and Western blot assays to determine their titers and integrity of capsid proteins, respectively. Alternatively, the vectors based on wild-type capsid were pre-incubated with melittin, followed by transduction of cultured cells or tail vein administration of the mixture to C57BL/6 and BALB/c nude mice. In vivo bioluminescence imaging was performed to evaluate the transgene expression.@*RESULTS@#rAAV2 vectors with melittin peptide inserted in the loop VIII of VPs had low transduction efficiency, probably due to dramatically reduced ability to bind to the target cells. Fusing the melittin peptide at the N-terminus of VP2 produced vectors without the VP2 subunit. Interestingly, among the commonly used rAAV vectors, pre-incubation of rAAV2 and rAAV6 vectors with melittin significantly enhanced their transduction efficiency in HEK293 and Huh7 cells in vitro. Melittin also had the ability to increase the rAAV2-mediated transgene expression in mouse liver in vivo. Mechanistically, melittin did not change the vector-receptor interaction. Moreover, cell counting kit-8 assays of cultured cells and serum transaminase levels indicated melittin had little cytotoxicity.@*CONCLUSION@#Pre-incubation with melittin, but not insertion of melittin into the rAAV2 capsid, significantly enhanced rAAV2-mediated transgene expression. Although further in vivo evaluations are required, this research not only expands the pharmacological potential of melittin, but also provides a new strategy to improve gene therapy mediated by rAAV vectors.

Anaphylactic shock with pulmonary eosinophilic infiltration due to honeybee attack in a donkey: case report / [Choque anafilático com infiltração eosinófila pulmonar devido a ataque de abelhas em um burro: relato de caso]

A case of a donkey attacked by Africanized honeybee is reported here with clinical signs of agitation, dehydration, congestion of the ocular mucous membranes, tongue edema, tachycardia and inspiratory dyspnea, and progression to death. At necropsy, diffuse, severe subcutaneous edema at face and cervical regions and severe diffuse pulmonary hyperemia with abundant edema without parenchymal collapse were observed. Microscopically, marked, diffuse deep dermis and panniculus carnosus edema and marked diffuse alveolar edema, with moderate population of eosinophils predominantly around larger caliber vessels were noted. The final diagnosis of anaphylactic shock was supported by history, clinical signs, and anatomic pathology findings. This is the first report of a honeybee attack with pulmonary eosinophilic infiltration in a mammal.(AU)

Descreve-se um caso de ataque de abelha africanizada em um burro, com sinais clínicos de agitação, desidratação, mucosas oculares congestas, edema de língua, taquicardia e dispneia inspiratória, com progressão e morte. Na necropsia, foram verificados edema subcutâneo difuso grave nas regiões de face e cervical, hiperemia pulmonar difusa grave com edema abundante e sem colapso do parênquima. Microscopicamente, foram observados edema marcado difuso na derme profunda e panículo carnoso e edema alveolar difuso acentuado, com população moderada de eosinófilos predominantemente em torno de vasos de maior calibre. O diagnóstico de choque anafilático foi baseado no histórico, em sinais clínicos e em achados anatomopatológicos. Este é o primeiro relato de ataque de abelhas com infiltração eosinofílica pulmonar em um mamífero.(AU)

Melittin-induced metabolic changes on the Madin-Darby Bovine Kidney cell line / [Mudanças metabólicas induzidas por melitina em células da linhagem Madin-Darby Bovine Kidney]

In this study, the toxic effects of melittin on Madin-Darby Bovine Kidney cells (MDBK) were analyzed with respect to mitochondrial functionality by reduction of MTT and flow cytometry, apoptosis potential, necrosis, oxygen reactive species (ROS) production, lipid peroxidation, and DNA fragmentation using flow cytometry and cell membrane destabilization by confocal microscopy. The toxicity presented dose-dependent characteristics and mitochondrial activity was inhibited by up to 78.24 ±3.59% (P<0.01, n = 6) in MDBK cells exposed to melittin (10µg/mL). Flow cytometry analysis revealed that melittin at 2µg/mL had the highest necrosis rate (P<0.05) for the cells. The lipoperoxidation of the membranes was also higher at 2µg/mL of melittin (P<0.05), which was further confirmed by the microphotographs obtained by confocal microscopy. The highest ROS production occurred when the cells were exposed to 2.5µg/mL melittin (P<0.05), and this concentration also increased DNA fragmentation (P<0.05). There was a significative and positive correlation between the lipoperoxidation of membranes with ROS (R=0.4158), mitochondrial functionality (R=0.4149), and apoptosis (R=0.4978). Thus, the oxidative stress generated by melittin culminates in the elevation of intracellular ROS that initiates a cascade of toxic events in MDBK cells.(AU)

Neste estudo, os efeitos tóxicos da melitina em células Madin-Darby Bovine Kidney (MDBK) foram analisados quanto à funcionalidade mitocondrial, por redução de MTT e citometria de fluxo, potencial de apoptose, necrose, produção de espécies reativas de oxigênio (ROS), peroxidação lipídica e fragmentação de DNA, utilizando-se citometria de fluxo e desestabilização da membrana celular, por microscopia confocal. A toxicidade apresentou características dose-dependentes e a atividade mitocondrial foi inibida até 78,24±3,59% (P<0,01, n = 6) em células MDBK expostas à melitina (10µg/mL). Análises por citometria de fluxo revelaram que a melitina a 2µg/mL apresentou o maior índice necrótico celular (P<0,05). A maior lipoperoxidação de membranas também foi na concentração de 2µg/mL de melitina (P<0,05), o que foi posteriormente confirmado por microscopia confocal. A maior produção de ROS aconteceu quando as células foram expostas a 2,5µg/mL de melitina (P<0,05), e essa concentração também aumentou a fragmentação de DNA (P<0,05). Houve uma significativa correlação positiva entre a lipoperoxidação de membranas e a produção de ROS (R=0,4158), funcionalidade mitocondrial (R=0,4149) e apoptose (R=0,4978). Portanto, o estresse oxidativo gerado pela melitina culminou na elevação de ROS intracelular, que inicia uma cascata de eventos tóxicos nas células MDBK.(AU)

Melittin suppresses growth and induces apoptosis of non-small-cell lung cancer cells via down-regulation of TGF-ß-mediated ERK signal pathway

The purpose of this study was to investigate the anti-cancer effect of melittin on growth, migration, invasion, and apoptosis of non-small-cell lung cancer (NSCLC) cells. This study also explored the potential anti-cancer mechanism of melittin in NSCLC cells. The results demonstrated that melittin suppressed growth, migration, and invasion, and induced apoptosis of NSCLC cells in vitro. Melittin increased pro-apoptotic caspase-3 and Apaf-1 gene expression. Melittin inhibited tumor growth factor (TGF)-β expression and phosphorylated ERK/total ERK (pERK/tERK) in NSCLC cells. However, TGF-β overexpression (pTGF-β) abolished melittin-decreased TGF-β expression and pERK/tERK in NSCLC cells. Treatment with melittin suppressed tumor growth and prolonged mouse survival during the 120-day observation in vivo. Treatment with melittin increased TUNEL-positive cells and decreased expression levels of TGF-β and ERK in tumor tissue compared to the control group. In conclusion, the findings of this study indicated that melittin inhibited growth, migration, and invasion, and induced apoptosis of NSCLC cells through down-regulation of TGF-β-mediated ERK signaling pathway, suggesting melittin may be a promising anti-cancer agent for NSCLC therapy.

Potencial antiviral e virucida da melitina e apamina contra herpesvírus bovino tipo 1 e vírus da diarreia viral bovina / Antiviral and virucidal potential of melittin and apamin against bovine herpesvirus type 1 and bovine viral diarrhea virus

A busca por alternativa aos fármacos sintéticos têm revelado descobertas no campo da farmacologia e, nesse sentido, melitina e apamina, dois constituintes do veneno de abelhas, foram descritas com várias ações farmacológicas. Este estudo objetivou avaliar in vitro as capacidades antiviral e virucida destes componentes. Para tanto, células MDBK (Madin Darby Bovine Kidney), após verificação das respectivas doses tóxicas por ensaio MTT ((3-(4,5 dimetiltiazol-2yl)-2-5-difenil-2H tetrazolato de bromo), foram cultivadas em microplacas e tratadas com diferentes concentrações de apamina, melitina e sua associação. Esse tratamento ocorreu antes e após a infecção com 0,1 MOI (multiplicidade de infecção) de cepas citopatogênicas de herpesvírus bovino tipo 1 (BoHV-1) cepa Los Angeles e vírus da diarreia viral bovina (BVDV) cepa NADL. Após incubação por 72 horas, 37oC, as células foram submetidas ao ensaio MTT para estimativa da viabilidade celular. Em experimento paralelo, placas que foram submetidas ao mesmo procedimento sofreram ciclo de congelamento e descongelamento das células, para rompimento das mesmas e mensuração dos títulos virais. O ensaio virucida foi realizado incubando-se suspensões de BoHV-1 e BVDV com as soluções de apamina, melitina e associação por 24 horas a 37oC e 22oC. O título viral foi avaliado às 0 horas, 1, 2, 4, 8 e 24 horas de incubação. A concentração citotóxica para 50% das células (CC50) de melitina foi 2,32 μg/ml e apamina não demonstrou toxicidade à maior concentração testada (100μg/ml). Houve efeito antiviral da melitina sobre BoHV-1, especialmente na concentração de 2μg/ml, onde observou-se 85,96% de viabilidade celular quando o tratamento foi realizado antes da infecção e 86,78% de viabilidade quando o tratamento foi realizado após a infecção. Houve ainda redução de 90% das partículas virais de BoHV-1. Em menores concentrações (1 e 1,5μg/ml) de melitina não houve atividade antiviral, pois a viabilidade celular foi baixa, demonstrando efeito citopático do vírus. Na associação das duas substâncias houve queda no título de BVDV e observou-se maior viabilidade celular quando comparados à ação isolada dos composto sobre este vírus. Isso se confirma na atividade virucida, uma vez que houve decréscimo de 90% das partículas virais de BVDV com a associação dos dois compostos do veneno de abelhas. Atuando individualmente, melitina apresentou efeito antiviral e virucida frente ao BoHV-1, zerando seu título em apenas 2 horas a 37oC. Conclui-se que melitina tem ação antiviral e virucida frente ao BoHV-1 e sua associação com apamina potencializou seus efeitos frente ao BVDV.(AU)

The search for an alternative to synthetic drugs have revealed discoveries in the field of pharmacology and, according to melittin and apamin, two components of bee venom which have been described were with various pharmacological actions.This study aimed to evaluate the in vitro antiviral and virucidal capabilities of these components. Therefore, after verification of their toxic doses by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, MDBK cells (Madin Darby Bovine Kidney) have been cultivated in microplates and treated with different concentrations of apamin, melittin and its association. This treatment occurred before and after infection with MOI (multiplicity of infection) 0.1 of cytopathogenic strains of bovine herpesvirus type 1 (BoHV-1) strain Los Angeles and bovine viral diarrhea virus (BVDV) strain NADL. After incubation for 72 hours, 37°C, the cells were submitted to MTT assay to estimate cell viability. In parallel experiments, plates were subjected to the same procedure suffered freezing and thawing cycle the cells to rupture the same and measurement of viral titers. The virucidal assay was performed by incubating suspension of bovine herpesvirus type-1 and BVDV with apamin solutions, melittin and association for 24 hours at 37°C and 22°C. The viral titer was evaluated at 0 hours, 1, 2, 4, 8 and 24 hours of incubation. The cytotoxic concentration to 50% of the cells (CC50) of melittin was 2.32g/mL and apamin did not show toxicity at the greater concentration tested (100μg/mL). There was antiviral effect of melittin on bovine herpesvirus type-1, especially at a concentration of 2μg/mL, where was observed 85.96% cell viability when treatment was performed before the infection and 86.78% viability when the treatment was carried out after infection. There was also a 90% reduction of viral particles of bovine herpesvirus type-1. In lower concentrations (1 and 1.5μg/mL) melittin no antiviral activity because cell viability was low, showing cytopathic effect of the virus. At the association two substances there were a decrease in the title of BVDV and there was higher cell viability when compared to the isolated action of the compounds of this virus. This is confirmed in the virucidal activity, since there was a decrease of 90% of the viral particles of BVDV with the combination of the two compounds of bee venom. Acting individually, melittin showed antiviral effect and virucidal against for BoHV-1, zeroing its title in just 2 hours at 37°C. It is concluded that melittin has antiviral and virucidal action against the BoHV-1 and its association with apamin potentiate its effects against BVDV.(AU)

Antifungal Effects of Bee Venom Components on Trichophyton rubrum: A Novel Approach of Bee Venom Study for Possible Emerging Antifungal Agent

BACKGROUND: Bee venom (BV) has been widely investigated for potential medical uses. Recent inadvertent uses of BV based products have shown to mitigate signs of fungal infections. However, the component mediating the antifungal effect has not been identified. OBJECTIVE: This investigation compares bee venom in its whole and partial forms to evaluate the possible component responsible for the antifungal effect. METHODS: Forty-eight plates inoculated with Trichophyton rubrum were allocated into four groups. The groups were treated with raw BV (RBV), melittin, apamin and BV based mist (BBM) respectively and each group was further allocated accordingly to three different concentrations. The areas were measured every other day for 14 days to evaluate the kinetic changes of the colonies. RESULTS: The interactions of ratio differences over interval were confirmed in groups treated with RBV and BBM. In RBV, the level of differences were achieved in groups treated with 10 mg/100 µl (p=0.026) and 40 mg/100 µl (p=0.000). The mean difference of ratio in groups treated with RBV was evident in day 3 and day 5. The groups that were treated with melittin or apamin did not show any significant interaction. In BBM groups, the significant levels of ratio differences over time intervals were achieved in groups treated with 200 µl/100 µl (p=0.000) and 300 µl/100 µl (p=0.030). CONCLUSION: The the bee venom in its whole form delivered a significant level of inhibition and we concluded that the venom in separated forms are not effective. Moreover, BV based products may exert as potential antifungal therapeutics.

Melittin induces in vitro death of Leishmania (Leishmania) infantum by triggering the cellular innate immune response

Abstract Background Apis mellifera venom, which has already been recommended as an alternative anti-inflammatory treatment, may be also considered an important source of candidate molecules for biotechnological and biomedical uses, such as the treatment of parasitic diseases. Methods Africanized honeybee venom from Apis mellifera was fractionated by RP-C18-HPLC and the obtained melittin was incubated with promastigotes and intracellular amastigotes of Leishmania (L.) infantum. Cytotoxicity to mice peritoneal macrophages was evaluated through mitochondrial oxidative activity. The production of anti- and pro-inflammatory cytokines, NO and H2O2 by macrophages was determined. Results Promastigotes and intracellular amastigotes were susceptible to melittin (IC50 28.3 μg.mL−1 and 1.4 μg.mL−1, respectively), but also showed mammalian cell cytotoxicity with an IC50 value of 5.7 μg.mL−1. Uninfected macrophages treated with melittin increased the production of IL-10, TNF-α, NO and H2O2. Infected melittin-treated macrophages increased IL-12 production, but decreased the levels of IL-10, TNF-α, NO and H2O2. Conclusions The results showed that melittin acts in vitro against promastigotes and intracellular amastigotes of Leishmania (L.) infantum. Furthermore, they can act indirectly on intracellular amastigotes through a macrophage immunomodulatory effect.

Research on stability of melittin in different solvent systems / 中国中药杂志

The stability of melittin in different solvents (water, deoxygenated water, physiological saline, PBS, 50% ethanol, ethanol, glycerol)was studied and the results showed that the stability of melittin is not influenced by light, temperature and pH in 50% ethanol, which melittin can be completed dissolved when compared with ethanol and glycerol, in such, 50% ethanol was chosen as solvent storage when measured content of melittin. Then the effect of different concentrations of PBS, the pH of PBS and rat skin ho- mogenates were tested, and the results showed that melittin was degraded rapidly at low concentration solution and low ionic strength. Increasing pH of PBS and rat skin homogenate can accelerate the degradation of melittin. These researches provide an experimental ba- sis for further study of melittin.

Synergistic interaction between melittin and chemotherapeutic agents and their possible mechanisms: an experimental research / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To evaluate the effect of melittin and 5-Fu, DDP, and TXT on human gastric cancer cell line BGC-823 and to primarily explore their possible mechanisms.</p><p><b>METHODS</b>Median effect analysis was employed to determine the interaction between melittin and 5-Fu, DDP, TXT by analyzing the relationship between fraction affected (FA) and the combination index (CI) acquired from the dose-effect curve. Expressions of chemotherapeutic agent-associated genes of BGC-823 cells with or without treatment were measured by real-time fluorescent quantitative PCR.</p><p><b>RESULTS</b>(1) Both melittin and chemotherapeutic agents inhibited the growth of BGC-823. (2) For BGC-823 cells were acted by 5-Fu +melittin, when FA ranged between 0.35-0.75, CI was less than 1. For BGC-823 cells were acted by DDP + melittin, when FA ranged 0.55 or so, CI = 1; when Fa ranged below 0.55, CI was less than 1. For BGC-823 cells were acted by TXT + melittin, CI less than 1 could be seen in the whole interval. (3) After treatment suppressed were the expressions of chemotherapeutic agent-associated genes of BGC-823 cells such as thymidylate synthetase (TS), excision repair cross-complementing gene 1 (ERCC1), breast cancer susceptibility gene 1 (BRCA1), beta-tubulin III (TUBB3), and microtubule-associated protein tau (MAPT).</p><p><b>CONCLUSIONS</b>Melittin had a synergistic effect on the cytotoxicity of chemotherapeutic agents. The possible mechanisms might be associated with down-regulating chemotherapeutic agent-associated genes.</p>

Melittin Ameliorates the Inflammation of Organs in an Amyotrophic Lateral Sclerosis Animal Model

Amyotrophic lateral sclerosis (ALS) is a devastating progressive neurodegenerative disorder characterized by a selective loss of motor neurons in the spinal cord, brainstem, and motor cortex, leading to weakness of the limb and bulbar muscles. Although the immediate cause of death in ALS is the destruction of motor neurons, ALS is a multi-organ disease that also affects the lungs, spleen, and liver. Melittin is one of components of bee venom and has anti-neuroinflammatory effects in the spinal cord, as shown in an ALS animal model. To investigate the effects of melittin on inflammation in the lungs and spleen, we used hSOD1(G93A) transgenic mice that are mimic for ALS. Melittin treatment reduced the expression of inflammatory proteins, including Iba-1 and CD14 by 1.9- and 1.3-fold (p<0.05), respectively, in the lungs of symptomatic hSOD1(G93A) transgenic mice. In the spleen, the expression of CD14 and COX2 that are related to inflammation were decreased by 1.4 fold (p<0.05) and cell survival proteins such as pERK and Bcl2 were increased by 1.3- and 1.5-fold (p<0.05) in the melittin-treated hSOD1G93A transgenic mice. These findings suggest that melittin could be a candidate to regulate the immune system in organs affected by ALS.

Intracellular Ca2+ Mobilization and Beta-hexosaminidase Release Are Not Influenced by 60 Hz-electromagnetic Fields (EMF) in RBL 2H3 Cells

The effects of extremely low frequency electromagnetic fields (EMF) on intracellular Ca2+ mobilization and cellular function in RBL 2H3 cells were investigated. Exposure to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h did not produce any cytotoxic effects in RBL 2H3 cells. Melittin, ionomycin and thapsigargin each dose-dependently increased the intracellular Ca2+ concentration. The increase of intracellular Ca2+ induced by these three agents was not affected by exposure to EMF (60 Hz, 1 mT) for 4 or 16 h in RBL 2H3 cells. To investigate the effect of EMF on exocytosis, we measured beta-hexosaminidase release in RBL 2H3 cells. Basal release of beta-hexosaminidase was 12.3+/-2.3% in RBL 2H3 cells. Exposure to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h did not affect the basal or 1 microM melittin-induced beta-hexosaminidase release in RBL 2H3 cells. This study suggests that exposure to EMF (60 Hz, 0.1 or 1 mT), which is the limit of occupational exposure, has no influence on intracellular Ca2+ mobilization and cellular function in RBL 2H3 cells.

Cloning and expression of a gene encoding shortened LfcinB(1-15)-Melittin(5-12) hybrid peptide in Escherichia coli BL21(DE3) / 生物工程学报

In order to get new antibacterial peptide, we designed a hybrid peptide LfcinB(1-15)-Melittin(5-12), composed of 1-15 amino acid residues of bovine Lactoferricin and 5-12 amino acid residues of Melittin. According to the bias of codon utilization of Escherichia coli, We synthesized the gene encoding the hybrid peptide. We inserted the gene between the sites of Nco I and Sal I of pET-32a and obtained the recombinant expression vector for heterologous expression of LfcinB(1-15)-Melittin(5-12) in Escherichia coli. We used Escherichia coli BL21(DE3) as expression host for the recombinant plasmid. After induced by isopropyl-beta-D-thiogalactoside (IPTG) under the optimized conditions, we realized the fusion protein was successfully expressed. The fusion protein was expressed in soluble form and the level was more than 35% of the total proteins. With (His)6 x Tag, the fusion protein was easily purified by His x Bind Purification Kit. After purification, we obtained 35 mg of fusion protein from 1 L of culture medium. At last, we accomplished that the peptide LfcinB(1-15)-Melittin(5-12) was released from the fusion protein cleaved by enterokinase. The recombinant LfcinB(1-15)-Melittin(5-12) showed antimicrobial activity assayed by agar diffusion test. This is the first report on the heterologous expression of the hybrid antibacterial peptide LfcinB(1-15)-Melittin(5-12) in Escherichia coli and also provides basis for next cost-effective expression of other antimicrobial peptides in genetic engineering.

The Effect of Caffeic Acid on Wound Healing in Skin-incised Mice

This study was carried out to investigate the wound healing effect of caffeic acid in skin-incised mice. Caffeic acid showed significant effects on anti-inflammatory activity and wound healing, such as myeloperoxidase activity, lipid peroxidation, phospholipase A2 activity and collagen-like polymer synthesis, in incised-wound tissue. On the other hand, it significantly stimulated collagen-like polymer synthesis in NIH 3T3 fibroblast cells, while inhibited both silica-induced reactive oxygen species generation and melittin-induced arachidonic acid release and PGE2 production in Raw 264.7 cells, and histamine release in RBL 2H3 cells stimulated by melittin or arachidonic acid. Therefore, caffeic acid appears to have a potent antioxidant and anti-inflammatory effect in cell culture system, which may be related to wound healing in skin-incised mice.

Spinal Metabotropic Glutamate Receptors (mGluRs) are Involved in the Melittin-induced Nociception in Rats

Intraplantar injection of melittin has been known to induce sustained decrease of mechanical threshold and increase of spontaneous flinchings. The present study was undertaken to investigate how the melittin-induced nociceptive responses were modulated by changes of metabotropic glutamate receptor (mGluR) activity. Changes in paw withdrawal threshold (PWT), number of flinchings and paw thickness were measured at a given time point after injection of melittin (10microgram/paw) into the mid-plantar area of rat hindpaw. To observe the effects of mGluRs on the melittin-induced nociceptions, group I mGluR (AIDA, 100microgram and 200microgram), mGluR1 (LY367385, 50microgram and 100microgram) and mGluR5 (MPEP, 200microgram and 300microgram) antagonists, group II (APDC, 100microgram and 200microgram) and III (L-SOP, 100microgram and 200microgram) agonists were intrathecally administered 20 min before melittin injection. Intraplantar injection of melittin induced a sustained decrease of mechanical threshold, spontaneous flinchings and edema. The effects of melittin to reduce mechanical threshold and to induce spontaneous flinchings were significantly suppressed following intrathecal pre-administration of group I mGluR, mGluR1 and mGluR5 antagonists, group II and III mGluR agonists. Group I mGluR antagonists and group II and III mGluR agonists had no significant effect on melittin-induced edema. These experimental findings indicate that multiple spinal mGluRs are involved in the modulation of melittin-induced nociceptive responses.

Enhancing transfection efficiency of polyethylenimine by a hydrophobic peptide from bee venom / 中国实验血液学杂志

The study was aimed to investigate the possibility of enhancing transfection efficiency of branched polyethylenimine (BPEI) in HeLa cells by hydrophobic tail of bee venom peptide (melittin). Hydrophobic tail of melittin was synthesized and its membrane permeable activity was evaluated by hemolysis test. The peptide was mixed with BPEI and the transfection efficiency was determined in HeLa cells by using green fluorescent protein gene (GFP) as a reporter gene. The cytotoxicity of the mixture was analyzed by MTT assay at 24 hours after transfection. The results indicated that the synthesized peptide had permeable activity leading to hemolysis in both neutral and acidic solution. At optimal condition, the peptide could significantly improve the transfection efficiency of BPEI and the cytotoxicity of the mixture was lower than BPEI itself. It is concluded that hydrophobic tail of melittin may be a potential enhancer to improve transfection efficiency mediated by cationic polymers in difficult to transfect cells.

Multiple 5-Hydroxytryptamine (5-HT) Receptors Are Involved in the Melittin-induced Nociceptive Responses in Rat I. Role of Peripheral 5-HT Receptor

Melittin-induced tonic pain model is characterized by local inflammation, edema, spontaneous flinchings, and sustained mechanical hypersensitivity. These nociceptive responses are mediated through selective activation of capsaicin-sensitive primary afferent fibers by melittin. The present study was undertaken to elucidate the role of peripheral 5-hydroxytryptamine (5-HT) receptors in the melittin-induced nociceptive responses. Changes in mechanical threshold, flinching behaviors and paw thickness were measured in rat intraplantarly injected with melittin (40microgram/paw) alone or treated together with melittin and 5-HT receptor antagonists. WAY-100635 (100microgram & 200microgram/paw), isamoltane hemifumarate (100microgram & 200microgram/paw), methysergide maleate (60microgram, 120microgram & 200microgram/paw) and ICS-205,930 (100microgram & 200microgram/paw) were intraplantarly injected 20 min before melittin injection. All 5-HT receptor antagonists tested in this experiment significantly attenuated the ability of melittin to reduce mechanical threshold and to induce flinching behaviors. 5-HT receptor antagonists, except ICS-205,930, had mild inhibitory effect on melittin-induced edema. These experimental findings suggest that multiple peripheral 5-HT receptors are involved in the melittin-induced nociceptive responses.

Preparation and in vitro tumor cells selectivity of sterically stabilized immunoliposomal peptides in bee venom / 药学学报

Recently the use of peptides in bee venom (PBV) for cancer therapy has attracted considerable attention. In this study, the sterically stabilized liposomal PBV (PBV-SL) was prepared using soybean phosphatidylcholine, cholesterol, and cholesterol-PEG-COOH. The humanized antihepatoma disulfide-stabilized Fv (hdscFv25) was coupled to sterically stabilized liposomes using the N-hydroxysuccinimide ester method. The hdscFv25-immunoliposomes (SIL[hdscFv25]) were immunoreactive as determined by ELISA assay. SIL[hdscFv25] showed higher tumor cells selectivity. PBV-SIL[hdscFv25] can kill SMMC-7721 cells in vitro with higher efficiency than non-targeted liposomes. Whereas cytotoxicties were compared for Hela cells, no significant differences was observed between PBV-SIL[hdscFv25] and PBV-SL. Sterically stabilized immunoliposomal peptides in bee venom could be one drug targeting delivery system.

Melittin inhibits proliferation and induces apoptosis of malignant human glioma cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the anti-tumor effects of melittin against malignant human glioma cells in vitro.</p><p><b>METHODS</b>Two malignant human glioma cell lines (U87 and U251) were treated with melittin at various concentrations, and the cell growth inhibition and apoptosis were evaluated using MTT assay, flow cytometry and agarose gel electrophoresis.</p><p><b>RESULTS</b>Melittin could obviously inhibit the proliferation of the two glioma cell lines (P<0.05). At the concentrations of 1, 10, 20, 40, 80, 160, 200 mg/L, melittin resulted in U87 cell apoptosis rates of 12.80%, 16.92%, 22.69%, 34.05%, 41.82%, 59.87%, and 80.25%, and in U251 cell apoptosis rate of 11.61%, 16.21%, 22.03%, 30.57%, 41.10%, 58.33%, and 79.12%, respectively, showing a dose-dependent effect in its action of inducing cell apoptosis.</p><p><b>CONCLUSION</b>Melittin inhibits the proliferation and induces apoptosis of malignant human glioma cell lines in vitro.</p>

Toxinas naturales: abejas y su veneno / Natural toxins: bees and venom

El veneno de Apis mellífera es una mezcla compleja de compuestos por moléculas de alto y bajo peso molecular, enzimas y peptidos, de los cuales la fosfolipasa A2, melitina y apamina son los compuestos causantes de los accidentes fatales en el ser humano y mamíferos. Provocando además, daño local en el sitio de picadura y otos efectos graves, tales como reacciones sistémicas. La toxicidad del veneno de abeja, sobre los humanos, no se conoce con exactitud, la dosis letal 50 en ratones, del veneno liofilizado y purificado es de 2.5 a 2.8 mg/kg por vía endovenosa y la dosis letal es de 6 mg/kg por vía endovenosa. Cuando una abeja pica, inyecta de 50 a 100 µg de veneno. Los efectos tóxicos de la picadura son provocados inmediatamente, el inicio de la anaflaxis es típico y rápido, desencadenado minutos después de la picadura. La enfermedad del suero puede ocurrir 10 a 14 días después del accidente. Cien picaduras pueden ser necesarias para matar a un humano, auqnue hay otros casos donde una picadura puede provocar la muerte y otras que han picado 400 ó más y han sobrevivido.

Calcium Ions are Involved in Modulation of Melittin-induced Nociception in Rat: I. Effect of Voltage-gated Calcium Channel Antagonist

Melittin-induced nociceptive responses are mediated by selective activation of capsaicin-sensitive primary afferent fibers and are modulated by excitatory amino acid receptor, cyclooxygenase, protein kinase C and serotonin receptor. The present study was undertaken to investigate the peripheral and spinal actions of voltage-gated calcium channel antagonists on melittin-induced nociceptive responses. Changes in mechanical threshold and number of flinchings were measured after intraplantar (i.pl.) injection of melittin (30microg/paw) into mid-plantar area of hindpaw. L-type calcium channel antagonists, verapamil [intrathecal (i.t.), 6 or 12microg; i.pl.,100 & 200microg; i.p., 10 or 30 mg], N-type calcium channel blocker, omega-conotoxin GVIA (i.t., 0.1 or 0.5microg; i.pl., 5microg) and P-type calcium channel antagonist, omega-agatoxin IVA (i.t., 0.5microg; i.pl., 5microg) were administered 20 min before or 60 min after i.pl. injection of melittin. Intraplantar pre-treatment and i.t. pre- or post-treatment of verapamil and omega-conotoxin GVIA dose-dependently attenuated the reduction of mechanical threshold, and melittin-induced flinchings were inhibited by i.pl. or i.t. pre-treatment of both antagonists. P-type calcium channel blocker, omega-agatoxin IVA, had significant inhibitory action on flinching behaviors, but had a limited effect on melittin-induced decrease in mechanical threshold. These experimental findings suggest that verapamil and omega-conotoxin GVIA can inhibit the development and maintenance of melittin-induced nociceptive responses.