Melittin binds to secretory phospholipase A2 and inhibits its enzymatic activity

Single-molecule phospholipase A2 becomes processive on melittin-induced membrane deformations

While it is established that the topology of lipid membranes plays an important role in biochemical processes, few direct observations exist regarding how the membranes are actively restructured and its consequences on subsequent reactions. In this work, we investigated how the two major components of bee venom, melittin and phospholipase A₂ (PLA₂), achieve activation by such membrane remodeling. Their membrane-disrupting functions have been reported to increase when both are present, but the mechanism of this synergism had not been established. Using membrane reconstitution, we found that melittin can form large-scale membrane deformities upon which PLA₂ activity is 25-fold higher. Tracking of single-molecule PLA₂ revealed that its processive behavior on these deformities underlies the enhanced activity. These results show how melittin and PLA₂ work synergistically to enhance the lytic effects of the bee venom. More broadly, they also demonstrate how the membrane topology may be actively altered to modulate cellular membrane-bound reactions.

Melittin-Based Nano-Delivery Systems for Cancer Therapy

Melittin (MEL) is a 26-amino acid polypeptide with a variety of pharmacological and toxicological effects, which include strong surface activity on cell lipid membranes, hemolytic activity, and potential anti-tumor properties. However, the clinical application of melittin is restricted due to its severe hemolytic activity. Different nanocarrier systems have been developed to achieve stable loading, side effects shielding, and tumor-targeted delivery, such as liposomes, cationic polymers, lipodisks, etc. In addition, MEL can be modified on nano drugs as a non-selective cytolytic peptide to enhance cellular uptake and endosomal/lysosomal escape. In this review, we discuss recent advances in MEL’s nano-delivery systems and MEL-modified nano drug carriers for cancer therapy.

Anti-inflammatory activities of arthropod peptides: a systematic review

Peptides obtained from different animal species have gained importance recently due to research that aims to develop biopharmaceuticals with therapeutic potential. In this sense, arthropod venoms have drawn attention, not only because of their toxicity but mainly for the search for molecules with various bioactivities, including anti-inflammatory activity. The purpose of the present study is to gather data available in the literature on new peptides derived from arthropod species with anti-inflammatory potential. This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Studies on peptides from arthropods that display anti-inflammatory activity were retrieved from PubMed, Scopus, Web of Science, and Google Scholar databases. The bibliographic research started in 2020 and searched papers without a limit on the publication date. The articles were analyzed using a search string containing the following terms: "Peptides" and "Anti-inflammatory", in combinations such as "Ant", "Bee", "Wasp", "Crab", "Shrimp", "Scorpion", "Spider", "Tick" and "Centipedes". Besides, a search was carried out in the databases with the terms: "Peptides", "Antitumor", or "Anticancer", and "Arthropods". Articles that met the inclusion and exclusion criteria totalized 171, and these served for data extraction. Additionally, the present review included anti-inflammatory peptides with anticancer properties. Peptides with confirmed anti-inflammatory activity were from insects (ants, bees, and wasps), crustaceans (shrimp and crabs), arachnids (scorpions, spiders, and ticks), and centipedes. These arthropod peptides act mainly by decreasing pro-inflammatory cytokines as analyzed in vitro and in vivo. Some showed significant antineoplastic activity, working in essential cellular pathways against malignant neoplasms.

Hepatoprotective activity of melittin on isoniazid- and rifampicin-induced liver injuries in male albino rats

Background

The present study investigated the ameliorative effect of melittin, a major polypeptide in the venom of honeybee (Apis mellifera), on isoniazid-(INH) and rifampicin-(RIF) induced hepatotoxicity in male albino rats.

Method

Thirty rats (140-200 g) were divided into five groups (n = 6): normal control (NC) received normal saline orally (NaCl, 0.9%; toxic (T) group received INH + RIF (each rat received 100 mg/kg, p.o.); melittin (Mel15, Mel30) groups (each rat received 15 or 30 μg/kg s.c); and normal recovery (NR) group received INH + RIF (each rat received 100 mg/kg, p.o.). Blood and liver samples were collected for biochemical, hematological and histopathological studies respectively.

Results

The administration of melittin was found to prevent the antitubercular drug-induced alterations in the diagnostic markers; reduced glutathione (GSH), direct bilirubin (DB), total bilirubin (TB), aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), and total serum protein (TSP). Besides, hematological alterations were significantly high in Mel groups when compared to the toxic group. The NR group exhibited lower levels of DB, TB, ALP, LDH and TSP. In addition, treatment with melittin offered protection in the NR group with respect to MDA levels.

Conclusion

Evidence from this study suggests that melittin is beneficial for the prevention of acute hepatic failure in antitubercular drug-induced hepatoxicity and could be used as a potential therapeutic agent.

Antiulcerogenic effect of melittin via mitigating TLR4/TRAF6 mediated NF-κB and p38MAPK pathways in acetic acid-induced ulcerative colitis in mice

Ulcerative colitis (UC) is a chronic disease driven primarily by uncontrolled pervasive inflammatory responses affecting the colon and rectum. Currently available medications carry multiple detrimental adverse effects, which have emphasized the mandatory need for safer and more efficient novel therapeutic alternatives. Melittin is the main constituent of bee venom and exhibits potent anti-inflammatory properties. The antiulcerogenic effect of oral melittin (40 μg/kg) was explored in the current study using the acetic acid-induced colitis model. Increase in body weight and decrease in colon mass index were observed in the melittin group. Microscopically, melittin ameliorated acetic acid-induced histological damage. Melittin administration has efficiently amended the elevated levels of the cytokines, tumor necrosis factor (TNF-α) and interleukin 6 (IL-6) seen in the colitis group. This was accompanied by inhibition of the upstream signaling molecules, Toll-like receptor 4 (TLR4), tumor necrosis factor receptor (TNF-R)-associated factor (TRAF6), mitogen-activated protein kinase 38 (p38 MAPK), and nuclear factor kappaB (NF-κB) in the melittin group. Moreover, treatment with melittin resulted in marked decrease in colonic level of prostaglandin E2 (PGE2) together with the enzymes involved in its synthesis, secretory phospholipase A2 (sPLA2) and cyclooxygenase 2 (COX-2). Additionally, melittin has attenuated acetic acid-induced oxidative stress as manifested by the significant diminishment in malondialdehyde (MDA) as well as the increase in superoxide dismutase (SOD) and reduced glutathione (GSH) levels. Therefore, melittin mitigated UC pathogenesis and could be considered as a potent and promising therapeutic alternative for UC treatment.

Comparison of ligand binding and conformational stability of human calmodulin with its homolog from the malaria parasite Plasmodium falciparum

Calmodulin (CaM), the key calcium sensor of eukaryotic cells regulating a great number of target proteins, belongs to the most conserved proteins. We compared function and properties of CaMs from two evolutionarily distant species, the human (Homo sapiens) representing vertebrates, and the malaria parasite Plasmodium falciparum (Pf). The biophysical characterization revealed higher stability of Pf CaM attributed to the more stable C-terminal domain in both Ca2+ free and saturated states. In vitro binding and functional assays demonstrated that human and Pf CaM exhibit similar biochemical features involving small molecule inhibitor binding and target enzyme activation as illustrated by comparable affinities differing only within a factor of three. It has been reported that CaM antagonists proved to be antimalarials, so Pf CaM could be a potential target to combat malaria parasites. Indeed, we observed that phenotypically active compounds from the Malaria Box could show inhibitory action on Pf CaM, among them the most potent exhibited comparable inhibition to known antagonists of vertebrate CaM. However, based on the minor binding differences in Pf CaM to human CaM, we conclude that CaM is an unsuited target for human intervention against malaria, due to the likely interference with the host protein.

Unity Makes Strength: Exploring Intraspecies and Interspecies Toxin Synergism between Phospholipases A2 and Cytotoxins

Toxin synergism is a complex biochemical phenomenon, where different animal venom proteins interact either directly or indirectly to potentiate toxicity to a level that is above the sum of the toxicities of the individual toxins. This provides the animals possessing venoms with synergistically enhanced toxicity with a metabolic advantage, since less venom is needed to inflict potent toxic effects in prey and predators. Among the toxins that are known for interacting synergistically are cytotoxins from snake venoms, phospholipases A₂ from snake and bee venoms, and melittin from bee venom. These toxins may derive a synergistically enhanced toxicity via formation of toxin complexes by hetero-oligomerization. Using a human keratinocyte assay mimicking human epidermis in vitro, we demonstrate and quantify the level of synergistically enhanced toxicity for 12 cytotoxin/melittin-PLA₂ combinations using toxins from elapids, vipers, and bees. Moreover, by utilizing an interaction-based assay and by including a wealth of information obtained via a thorough literature review, we speculate and propose a mechanistic model for how toxin synergism in relation to cytotoxicity may be mediated by cytotoxin/melittin and PLA₂ complex formation.

Bee venom therapy: Potential mechanisms and therapeutic applications

Bee venom is a very complex mixture of natural products extracted from honey bee which contains various pharmaceutical properties such as peptides, enzymes, biologically active amines and nonpeptide components. The use of bee venom into the specific points is so called bee venom therapy, which is widely used as a complementary and alternative therapy for 3000 years. A growing number of evidence has demonstrated the anti-inflammation, the anti-apoptosis, the anti-fibrosis and the anti-arthrosclerosis effects of bee venom therapy. With these pharmaceutical characteristics, bee venom therapy has also been used as the therapeutic method in treating rheumatoid arthritis, amyotrophic lateral sclerosis, Parkinson's disease, Alzheimer's disease, liver fibrosis, atherosclerosis, pain and others. Although widely used, several cases still reported that bee venom therapy might cause some adverse effects, such as local itching or swelling. In this review, we summarize its potential mechanisms, therapeutic applications, and discuss its existing problems.

Anti-inflammatory effect of bee venom in an allergic chronic rhinosinusitis mouse model

Bee venom (BV) has long been used as anti-inflammatory agent in traditional oriental medicine; however, the effect of BV on chronic rhinosinusitis (CRS) is not commonly studied. The aim of the present study was to determine the anti-inflammatory effect of BV on an allergic CRS mouse model. An allergic CRS mouse model was established following the administration of ovalbumin with Staphylococcus aureus enterotoxin B (SEB) into the nose. A total of 0.5 or 5 ng/ml of BV were intranasally applied 3 times a week for 8 weeks. Histopathological alterations were observed using hematoxylin and eosin, and Periodic acid Schiff staining. The levels of inflammatory cell infiltration, interleukin (IL)‑4, IL‑10 and interferon (INF)‑γ in nasal lavage fluid (NLF) were measured. Nuclear factor (NF)‑κB and activator protein (AP)‑1 expressions were also determined by immunohistochemical staining. The group treated with BV had significantly decreased inflammatory cell infiltration and PAS‑positive cells. The levels of INF‑γ, and neutrophil and eosinophil counts in NLF were significantly decreased, and the SEB‑induced NF‑κB and AP‑1 expressions in mouse nasal mucosa were significantly suppressed by 0.5 and 5 ng/ml BV. Thus, BV exerted significant anti‑inflammatory effects in an allergic CRS mouse model and may have potential value for the treatment of CRS.

Bee venom for the treatment of Parkinson's disease: How far is it possible?

Parkinson's disease (PD) is the second most common neurodegenerative disease, characterized by progressive loss of dopaminergic neurons in the substantia nigra pars compacta leading to depletion of striatal dopamine and motor symptoms as bradykinesia, resting tremors, rigidity, and postural instability. Current therapeutic strategies for PD are mainly symptomatic and may cause motor complications, such as motor fluctuations and dyskinesia. Therefore, alternative medicine may offer an effective adjuvant treatment for PD. Bee venom therapy (BVT) has long been used as a traditional therapy for several conditions, such as rheumatoid arthritis, asthma, and skin diseases. Experimental and clinical studies showed that BVT could be an effective adjuvant treatment for PD. Several mechanisms were suggested for these findings including the ability of BVT to attenuate neuroinflammation, inhibit apoptosis of dopaminergic neurons, protect against glutamate-induced neurotoxicity, and restore normal dopamine levels in the nigrostriatal pathway. In this article, we reviewed and summarized the literature regarding the potential of BVT for the treatment of PD.

Antifungal Activity of Bee Venom and Sweet Bee Venom against Clinically Isolated Candida albicans

OBJECTIVES

The purpose of this study was to investigate the antifungal effect of bee venom (BV) and sweet bee venom (SBV) against Candida albicans (C. albicans) clinical isolates.

METHODS

In this study, BV and SBV were examined for antifungal activities against the Korean Collection for Type Cultures (KCTC) strain and 10 clinical isolates of C. albicans. The disk diffusion method was used to measure the antifungal activity and minimum inhibitory concentration (MIC) assays were performed by using a broth microdilution method. Also, a killing curve assay was conducted to investigate the kinetics of the anti- fungal action.

RESULTS

BV and SBV showed antifungal activity against 10 clinical isolates of C. albicans that were cultured from blood and the vagina by using disk diffusion method. The MIC values obtained for clinical isolates by using the broth microdilution method varied from 62.5 μg/ mL to 125 μg/mL for BV and from 15.63 μg/mL to 62.5 μg/mL for SBV. In the killing-curve assay, SBV behaved as amphotericin B, which was used as positive control, did. The antifungal efficacy of SBV was much higher than that of BV.

CONCLUSION

BV and SBV showed antifungal activity against C. albicans clinical strains that were isolated from blood and the vagina. Especially, SBV might be a candidate for a new antifungal agent against C. albicans clinical isolates.

Three valuable peptides from bee and wasp venoms for therapeutic and biotechnological use: melittin, apamin and mastoparan

While knowledge of the composition and mode of action of bee and wasp venoms dates back 50 years, the therapeutic value of these toxins remains relatively unexploded. The properties of these venoms are now being studied with the aim to design and develop new therapeutic drugs. Far from evaluating the extensive number of monographs, journals and books related to bee and wasp venoms and the therapeutic effect of these toxins in numerous diseases, the following review focuses on the three most characterized peptides, namely melittin, apamin, and mastoparan. Here, we update information related to these compounds from the perspective of applied science and discuss their potential therapeutic and biotechnological applications in biomedicine.

Bee venom at different concentrations modulates the aeroallergen-induced activation of nasal polyp epithelial cells

Bee venom (BV) has long been used as an oriental traditional medicine for the control of pain and inflammation. However, BV's anti-inflammatory mechanisms remain unclear. This study aimed to clarify the potential clinical efficacy of BV concerning the anti-inflammatory effect on nasal epithelial cell inflammation. Nasal polyp epithelial cells were obtained from patients. Cells were exposed to Alternaria alternata, Aspergillus nigra, Dermatophagoides pteronyssinus, Dermatophagoides farina and lipopolysaccharide with or without various concentrations of BV. Interleukin (IL)-6, IL-8, and granulocyte macrophage colony-stimulating factor were measured to determine the activation of epithelial cells. Nuclear factor-ĸB (NF-ĸB) and activator protein 1 expression and activity were determined with Western blot analysis and ELISA. Cytotoxicity of BV was measured using a CellTiter-96® aqueous cell proliferation assay kit. Cell survival was significantly decreased at BV concentrations exceeding 5 µg/ml. Fungi-induced cytokine production was more effectively inhibited by BV than house dust mite. Alternaria enhanced NF-ĸB expression, which was strongly inhibited by BV. BV appears to be relatively safe, and is of potential value for the treatment of airway inflammation and/or immunologic diseases.

Anti-inflammatory Effect of Bee Venom on Type II Collagen-Induced Arthritis

Bee venom (BV) has been used to relieve pain and reduce inflammation in traditional Oriental medicine, especially in chronic inflammatory diseases such as rheumatoid arthritis (RA). We previously reported that the BV injection into a traditional acupuncture point (Zusanli) reduced arthritis-associated edema and nociceptive responses in Freund's adjuvant-induced arthritis in rats (Kwon et al., 2001). This study was designed to evaluate the anti-inflammatory and anti-cytokine effect of BV on a murine type-II collagen-induced arthritis (CIA) model. Male mice were immunized by spontaneous injection of 100 μg of an emulsion of bovine type-II collagen and complete Freund's adjuvant (CFA), with a booster injection after 2 weeks. In the experimental group, 0.1 ml BV was injected at acupuncture point (Zusanli) near both knees twice a week for a total of 5 times. In the control group, normal saline was injected at the same frequencies. These injections began 5 weeks after the first collagen injection. Starting the 3rd week after the first collagen injection, we examined limb swelling and severity of arthritis twice a week. At 8 weeks, mice were sacrificed and synovial tissue was examined with the light microscope and serum cytokines (IL-1β and TNF-α) were measured by ELISA.

The incidence of arthritis, the mean arthritis index and the number of arthritic limbs were significantly lower in the treatment compared to the control group (63% versus 75%, 3.4% versus 8.5%, 23% versus 75%, respectively). Among the serum proinflammatory cytokines, the production of TNF-α in the BV group was suppressed compared to the control group (59+/-4.5 versus 99.5+/-6.5, p <0.05), but IL-1β was not suppressed. The examination of the histopathology of the joints of murine CIA showed decreased inflammation signs and less lymphocyte infiltration after BV acupuncture therapy. Acupuncture therapy with BV suppressed the development of arthritis and caused inhibition of the immune responses in type-II collagen-induced arthritis.

Melittin attenuates liver injury in thioacetamide-treated mice through modulating inflammation and fibrogenesis

Liver fibrosis represents a process of healing and scarring in response to chronic liver injury. Following injury, an acute inflammation response takes place resulting in moderate cell necrosis and extracellular matrix damage. Melittin, the major bioactive component in the venom of honey bee Apis mellifera, is a 26-residue amphipathic peptide with well-known cytolytic, antimicrobial and proinflammatory properties. However, the molecular mechanisms responsible for the anti-inflammatory activity of melittin have not been elucidated in liver fibrosis. We investigated whether melittin ameliorates liver inflammation and fibrosis in thioacetamide (TAA)-induced liver fibrosis. Two groups of mice were treated with TAA (200 mg/L, in drinking water), one of the groups of mice was co-treated with melittin (0.1 mg/kg) for 12 weeks while the other was not. Hepatic stellate cells (HSCs) were cultured with tumor necrosis factor α in the absence or presence of melittin. Melittin suppresses the expression of proinflammatory cytokines through the nuclear factor (NF)- κB signaling pathway. Moreover, melittin reduces the activity of HSCs in vitro, and decreases the expression of fibrotic gene responses in TAA-induced liver fibrosis. Taken together, melittin prevents TAA-induced liver fibrosis by inhibiting liver inflammation and fibrosis, the mechanism of which is the interruption of the NF- κB signaling pathway. These results suggest that melittin could be an effective agent for preventing liver fibrosis.

Evaluation of bee venom and hyaluronic acid in the intra-articular treatment of osteoarthritis in an experimental rabbit model

The aim of this study was to investigate bee venom and hyaluronic acid in the intra-articular treatment of osteoarthritis in an experimental rabbit model. Forty-five rabbits were used and they were randomly divided into three groups (BVI, BVII, and HA) and each group was divided to two subgroups to evaluate the radiologic, magnetic resonance imaging, histopathologic, and biochemical evaluation in post treatment second week (a) and twelfth week (b). Radiologically, a significant difference was observed in the HA group (P<0.05). The MRI evaluation of at any time in group BVI(b) was found to be different. No significant differences were seen between the groups, biochemically. Histopathologically, cellularity, and orthochromasia was evident with Safranin-O in the BVI(b) and BVII(a); adhesions were seen in the BVII(a) group and clustering of chondrocyte in the HA(b) group were found to be different. Consequently, intra-articular application of HA and BV for experimental model of osteoarthritis has no significant influence upon recovery after therapy.

Effects induced by Apis mellifera venom and its components in experimental models of nociceptive and inflammatory pain

The effects induced by Apis mellifera venom (AMV), melittin-free AMV, fraction with molecular mass < 10 kDa (F<₁₀) or melittin in nociceptive and inflammatory pain models in mice were investigated. Subcutaneous administration of AMV (2, 4 or 6 mg/kg) or melittin-free AMV (1, 2 or 4 mg/kg) into the dorsum of mice inhibited both phases of formaldehyde-induced nociception. However, F<₁₀ (2, 4 or 6 mg/kg) or melittin (2 or 3 mg/kg) inhibited only the second phase. AMV (4 or 6 mg/kg), but not F<₁₀, melittin-free AMV or melittin, induced antinociception in the hot-plate model. Paw injection of AMV (0.05 or 0.10 mg), F<₁₀ (0.05 or 0.1 mg) or melittin (0.025 or 0.050 mg) induced a nociceptive response. In spite of inducing nociception after paw injection, scorpion (Tityus serrulatus) or snake (Bothrops jararaca) venom injected into the dorsum of mice did not inhibit formaldehyde-induced nociception. In addition, AMV (6 mg/kg), but not F<₁₀ (6 mg/kg) or melittin (3 mg/kg), inhibited formaldehyde paw oedema. Concluding, AMV, F<₁₀ and melittin induce two contrasting effects: nociception and antinociception. AMV antinociception involves the action of different components and does not result from non-specific activation of endogenous antinociceptive mechanisms activated by exposure to noxious stimuli.

Effect of bee venom on transforming growth factor-beta1-treated hepatocytes

Bee venom (BV) has been used as treatment against a wide variety of ailments, including inflammatory diseases. Various studies have demonstrated anti-inflammatory and anticancer effects of BV. Transforming growth factor (TGF)-beta1 induces hepatocyte apoptosis via the mitochondrial permeability transition. However, there is no evidence or information regarding the antiapoptotic effect of BV on hepatocytes. The authors investigated the antiapoptotic effect of BV on TGF-beta1-treated hepatocytes. The results showed significant protection from DNA damage by BV treatment compared to corresponding TGF-beta1-treated hepatocytes without BV. BV suppressed TGF-beta1-induced activation of the bcl-2 family and caspase family of proteins, which resulted in inhibition of poly ADP-ribose polymerase (PARP) cleavage. Furthermore, BV is not cytotoxic in the low concentrations used in this study. Low concentrations of BV potently suppress the apoptotic response in TGF-beta1-treated hepatocytes; therefore, BV may have therapeutic potential for the treatment of liver diseases.

Activation of phospholipase A2 by temporin B: formation of antimicrobial peptide-enzyme amyloid-type cofibrils

Phospholipases A2 have been shown to be activated in a concentration dependent manner by a number of antimicrobial peptides, including melittin, magainin 2, indolicidin, and temporins B and L. Here we used fluorescently labelled bee venom PLA2 (PLA2D) and the saturated phospholipid substrate 1,2-dipalmitoyl-glycero-sn-3-phosphocholine (L-DPPC), exhibiting a lag-burst behaviour upon the initiation of the hydrolytic reaction by PLA2. Increasing concentrations of Cys-temporin B and its fluorescent Texas red derivative (TRC-temB) caused progressive shortening of the lag period. TRC-temB/PLA2D interaction was observed by Förster resonance energy transfer (FRET), with maximum efficiency coinciding with the burst in hydrolysis. Subsequently, supramolecular structures became visible by microscopy, revealing amyloid-like fibrils composed of both the activating peptide and PLA2. Reaction products, palmitic acid and 1-palmitoyl-2-lyso-glycero-sn-3-phosphocholine (lysoPC, both at >8 mol%) were required for FRET when using the non-hydrolysable substrate enantiomer 2,3-dipalmitoyl-glycero-sn-1-phosphocholine (D-DPPC). A novel mechanism of PLA2 activation by co-fibril formation and associated conformational changes is suggested.

Microarray analysis of gene expression profiles in response to treatment with bee venom in lipopolysaccharide activated RAW 264.7 cells

AIM OF THE STUDY

The therapeutic application of bee venom (BV) has been used in traditional medicine to treat diseases such as arthritis, rheumatism and pain. Macrophages produce molecules that are known to play roles in inflammatory responses.

MATERIAL AND METHODS

We performed microarray analysis to evaluate the global gene expression profiles of RAW264.7 macrophage cells treated with BV. In addition, six genes were subjected to real-time PCR to confirm the results of the microarray. The cells were treated with lipopolysaccharide (LPS) or BV plus LPS for 30 min or 1h.

RESULTS

124 genes were found to be up-regulated and 158 were found to be down-regulated in cells that were treated with BV plus LPS for 30 min, whereas 211 genes were up-regulated and 129 were down-regulated in cells that were treated with BV plus LPS for 1h when compared with cells that were treated with LPS alone. Furthermore, the results of real-time PCR were similar to those of the microarray. BV inhibited the expression of specific inflammatory genes that were up-regulated by nuclear factor-kappa B in the presence of LPS, including mitogen-activated protein kinase kinase kinase 8 (MAP3K8), TNF, TNF-alpha-induced protein 3 (TNFAIP3), suppressor of cytokine signaling 3 (SOCS3), TNF receptor-associated factor 1 (TRAF1), JUN, and CREB binding protein (CBP).

CONCLUSIONS

These results demonstrate the potent activity of BV as a modulator of the LPS-mediated nuclear factor-kappaB (NF-kappaB)/MAPK pathway in activated macrophages. In addition, these results can be used to understand other effects of BV treatment.

Melittin exhibits necrotic cytotoxicity in gastrointestinal cells which is attenuated by cholesterol

Melittin, a cationic antimicrobial peptide isolated from the venom of Apis mellifera, has shown potential as a permeability enhancer, transiently increasing intestinal permeability and enhancing the absorption of paracellular markers. Although it is cytotoxic to eukaryotic cells, its cytotoxicity is significantly lower in polarised epithelia compared to non-polarised cells. The aim of this study was to explore the mechanism of melittin cytotoxicity in gastrointestinal cells and to determine whether cytotoxicity was mediated by a necrotic or an apoptotic pathway. The role of cholesterol in melittin cytotoxicity was also examined. Using four distinct assays for apoptosis, phosphatidylserine translocation, caspase activation, DNA ladder formation and cell cycle analysis, no evidence of apoptotic pathway for cell death was observed with any of these approaches. It can therefore be concluded that cytotoxicity was likely to be mediated by necrosis in gastrointestinal epithelial cells. However, at low concentrations of melittin (<1 microM), BRDU uptake was enhanced, demonstrating proliferative effects of melittin at sub-lethal concentrations. Furthermore, melittin cytotoxicity was further enhanced by depletion of cholesterol, using methyl-beta-cyclodextrin, indicating that cholesterol depleting agents could be contradictory to its potential as an enhancer. Overall, although melittin appears to stimulate necrosis, with careful dosage selection the peptide could be considered for the oral delivery of poorly bioavailable drugs.

Effect of honey bee venom on microglial cells nitric oxide and tumor necrosis factor-alpha production stimulated by LPS

Abnormal activation of microglial cells has been implicated in various neurodegenerative diseases. Results showed that venom (KBV) produced and purified in Korea regulated lipopolysaccharides (LPS)-induced nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) in the murine microglia, BV-2 cell line. The production of proinflammatory cytokines, NO, and TNF-alpha was examined by LPS in BV-2 cell. The effect of KBV on the expression of inducible nitric oxide synthase (iNOS) and TNF-alpha was investigated by Western blot and RT-PCR in LPS-stimulated BV-2 cells. KBV suppressed the NO, iNOS, and TNF-alpha production, and decreased the levels of iNOS and TNF-alpha mRNA. These results suggest that KBV has anti-inflammatory properties that inhibit iNOS and TNF-alpha expression. KBV could be useful in inhibiting the production of inflammatory cytokine and NO production in neurodegenerative diseases. Further studies on the pharmacological aspects of the individual components of KBV are recommended.

Phospholipase A2-independent Ca2+ entry and subsequent apoptosis induced by melittin in human MG63 osteosarcoma cells

Melittin, a peptide from bee venom, is thought to be a phospholipase A(2) activator and Ca(2+) influx inducer that can evoke cell death in different cell types. However, the effect of melittin on cytosolic free Ca(2+) concentration ([Ca(2+)](i)) and viability has not been explored in human osteoblast-like cells. This study examined whether melittin altered [Ca(2+)](i) and killed cells in MG63 human osteosarcoma cells. [Ca(2+)](i) changes and cell viability were measured by using the fluorescent dyes fura-2 and WST-1, respectively. Melittin at concentrations above 0.075 microM increased [Ca(2+)](i) in a concentration-dependent manner. The Ca(2+) signal was abolished by removing extracellular Ca(2+). Melittin-induced Ca(2+) entry was confirmed by Mn(2+) quenching of fura-2 fluorescence at 360 nm excitation wavelength which was Ca(2+)-insensitive. The melittin-induced Ca(2+) influx was unchanged by modulation of protein kinase-C activity with phorbol 12-myristate 13-acetate (PMA) and GF 109203X, or inhibition of phospholipase A(2) with AACOCF(3) and aristolochic acid; but was substantially inhibited by blocking L-type Ca(2+) channels. At concentrations of 0.5 microM and 1 microM, melittin killed 33% and 45% of cells, respectively, via inducing apoptosis. Lower concentrations of melittin failed to kill cells. The cytotoxic effect of 1 microM melittin was completely reversed by pre-chelating cytosolic Ca(2+) with BAPTA. Taken together, these data showed that in MG63 cells, melittin induced a [Ca(2+)](i) increase by causing Ca(2+) entry through L-type Ca(2+) channels in a manner independent of protein kinase-C and phospholipase A(2) activity; and this [Ca(2+)](i) increase subsequently caused apoptosis.

Melittin inhibits inflammatory target gene expression and mediator generation via interaction with IkappaB kinase

We previously found that bee venom (BV) and melittin (a major component of BV) has anti-inflammatory effect by reacting with the sulfhydryl group of p50 of NF-kappaB. Since the sulfhydryl group is present in IkappaB kinase (IKKalpha and IKKbeta), anti-inflammatory effect of melittin via interaction with IKKs was investigated. We first examined binding of melittin to IKKs using surface plasmon resonance analyzer. Melittin binds to IKKalpha (K(d) = 1.34 x 10(-9) M) and IKKbeta (K(d) = 1.01 x 10(-9) M). Consistent with the high binding affinity, melittin (5 and 10 microg/ml) and BV (0.5, 1 and 5 microg/ml) suppressed sodium nitroprusside, TNF-alpha and LPS induced-IKKbeta and IKKbeta activities, IkappaB release, and NF-kappaB activity as well as the expressions of iNOS and COX-2, and the generation of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) in Raw 264.7 mouse macrophages and synoviocytes obtained from rheumatoid arthritis patients. The binding affinities of melittin to mutant IKKs, was reduced, and the inhibitory effect of melittin on IKK and NF-kappaB activities, and NO and PGE(2) generation were abrogated by the reducing agents or in Raw 264.7 transfected with mutant plasmid IKKalpha (C178A) or IKKbeta (C179A). These results suggest that melittin binding to the sulfhydryl group of IKKs resulted in reduced IKK activities, IkappaB release, NF-kappaB activity and generation of inflammatory mediators, indicating that IKKs may be also anti-inflammatory targets of BV.

Structural and functional behavior of biologically active monomeric melittin

Melittin is a well-known water-soluble toxic peptide present in bee venom of Apis mellifera, capable of interacting with and disrupting cell membranes thus producing many effects on living cells. Additionally, melittin induces activation of phospholipases and calmodulin upon interaction with cellular membranes. The conformation and aggregation state adopted by melittin in solution depends on several factors including the peptide concentration, ionic strength, pH and the nature of the ions in the aqueous medium. Such conformational dependence on the peptide environment gives new insights over the currently available 3D structures of melittin and, ultimately, over its biologically functional unit. Based on crystallographic data, the melittin tetramer has been proposed as its bioactive form. Contrarily to such data, we show in this work the results obtained from molecular dynamics simulations, which clearly indicate that the tetrameric organization of melittin is not stable under biological conditions dissociating after 2.5 ns through a 10 ns trajectory. We found that the tetrameric form of melittin is stable only in conditions of high pH and high peptide concentration in the molecular dynamics simulations. Moreover, when in plasma melittin appears to be a random coil monomer, folding only upon interaction with biological membranes. In summary, these findings elucidate several properties of melittin structure and dynamics, projecting significant implications in the study of its biological function.

Roles of phospholipase A2 isoforms in swelling- and melittin-induced arachidonic acid release and taurine efflux in NIH3T3 fibroblasts

Osmotic swelling of NIH3T3 mouse fibroblasts activates a bromoenol lactone (BEL)-sensitive taurine efflux, pointing to the involvement of a Ca(2+)-independent phospholipase A(2) (iPLA(2)) (Lambert IH. J Membr Biol 192: 19-32, 2003). We report that taurine efflux from NIH3T3 cells was not only increased by cell swelling but also decreased by cell shrinkage. Arachidonic acid release to the cell exterior was similarly decreased by shrinkage yet not detectably increased by swelling. NIH3T3 cells were found to express cytosolic calcium-dependent cPLA(2)-IVA, cPLA(2)-IVB, cPLA(2)-IVC, iPLA(2)-VIA, iPLA(2)-VIB, and secretory sPLA(2)-V. Arachidonic acid release from swollen cells was partially inhibited by BEL and by the sPLA(2)-inhibitor manoalide. Cell swelling elicited BEL-sensitive arachidonic acid release from the nucleus, to which iPLA(2)-VIA localized. Exposure to the bee venom peptide melittin, to increase PLA(2) substrate availability, potentiated arachidonic acid release and osmolyte efflux in a volume-sensitive, 5-lipoxygenase-dependent, cyclooxygenase-independent manner. Melittin-induced arachidonic acid release was inhibited by manoalide and slightly but significantly by BEL. A BEL-sensitive, melittin-induced PLA(2) activity was also detected in lysates devoid of sPLA(2), indicating that both sPLA(2) and iPLA(2) contribute to arachidonic acid release in vivo. Swelling-induced taurine efflux was inhibited potently by BEL and partially by manoalide, whereas the reverse was true for melittin-induced taurine efflux. It is suggested that in NIH3T3 cells, swelling-induced taurine efflux is dependent at least in part on arachidonic acid release by iPLA(2) and possibly also by sPLA(2), whereas melittin-induced taurine efflux is dependent on arachidonic acid release by sPLA(2) and, to a lesser extent, iPLA(2).

Effects of bee venom on the pro-inflammatory responses in RAW264.7 macrophage cell line

The purpose of this study is to elucidate the molecular mechanism of anti-inflammatory effect of bee venom (BV), which has been used for the treatment of various inflammatory diseases in oriental medicine. With this aim, we examined the effects of BV on the nitric oxide (NO) production by lipopolysaccharide (LPS) or sodium nitroprusside in RAW264.7 macrophages. We further investigated the effects of BV on the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear factor-kappaB (NF-kappaB) and mitogen-activated protein kinase (MAPK) with RT-PCR in LPS-stimulated RAW264.7 cells. BV suppressed the NO production and decreased the levels of iNOS, COX-2, NF-kappaB and MAPK mRNA in a dose-dependent manner. These results suggest that BV has an anti-inflammatory effect by inhibiting iNOS and COX-2 expression, possibly through suppression of NF-kappaB and MAPK expression.

Phospholipase A2 activating protein (PLAA) is required for 1alpha,25(OH)2D3 signaling in growth plate chondrocytes

Phospholipase A2 (PLA2) is pivotal in the rapid membrane-mediated actions of 1,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3]. Microarray analysis indicated that PLA2 activating protein (PLAA) mRNA is upregulated 6-fold before rat growth plate cells exhibit 1alpha,25(OH)2D3-dependent protein kinase C (PKC) increases, suggesting that it plays an important role in 1alpha,25(OH)2D3's mechanism of action. PLAA mRNA was confirmed in 1alpha,25(OH)2D3-responsive growth zone (prehypertrophic and upper hypertrophic cell zones) chondrocytes by RT-PCR and Northern blot in vitro and by in situ hybridization in vivo. PLAA protein was shown by Western blot and immunohistochemistry. PLAAs role in 1alpha,25(OH)2D3 signaling was evaluated in growth zone cell cultures using PLAA peptide. Arachidonic acid release was increased as was PLA2-specific activity in plasma membranes and matrix vesicles. PKCalpha, but not PKCbeta, PKCepsilon, or PKCzeta, was increased. PLAAs effect was comparable to that of 1alpha,25(OH)2D3 and was additive with 1alpha,25(OH)2D3. PLA2 inhibitors quinacrine and AACOCF3, and cyclooxygenase inhibitor indomethacin blocked the effect of PLAA peptide on PKC, indicating arachidonic acid and its metabolites were involved. This was confirmed using exogenous arachidonic acid. Prostaglandin acted via EP1 based on inhibition by SC19220 and not via EP2 since AH6809 had no effect. Like 1alpha,25(OH)2D3, PLAA peptide also increased activity of phospholipase C-specific activity via beta-1 and beta-3 isoforms, but not delta-1 or gamma-1; the effect of PLAA was via lysophospholipid but not via arachidonic acid. PLAA peptide decreased [3H]-thymidine incorporation to 50% of the decrease caused by 1alpha,25(OH)2D3. In contrast, PLAA peptide increased alkaline phosphatase-specific activity and proteoglycan production in a manner similar to 1alpha,25(OH)2D3. This indicates that PLAA is a specific activator of PLA2 in growth plate chondrocytes, and suggests that it mediates the membrane effect of 1alpha,25(OH)2D3, thereby modulating physiological response.

Toxins in anti-nociception and anti-inflammation

The use of toxins as novel molecular probes to study the structure-function relationship of ion-channels and receptors as well as potential therapeutics in the treatment of wide variety of diseases is well documented. The high specificity and selectivity of these toxins have attracted a great deal of interest as candidates for drug development. This review highlights the involvement of the proteins and peptide toxins as well as non-proteinaceous compounds derived from both venomous and non-venomous animals, in anti-nociception and anti-inflammation. The possible mechanisms of these potential therapeutic agents and possible clinical applications in the treatment of pain and inflammation are also summarized.

1alpha,25(OH)2D3 causes a rapid increase in phosphatidylinositol-specific PLC-beta activity via phospholipase A2-dependent production of lysophospholipid

1alpha,25(OH)(2)D(3) activates protein kinase C (PKC) in rat growth plate chondrocytes via mechanisms involving phosphatidylinositol-specific phospholipase C (PI-PLC) and phospholipase A(2) (PLA(2)). The purpose of this study was to determine if 1alpha,25(OH)(2)D(3) activates PI-PLC directly or through a PLA(2)-dependent mechanism. We determined which PLC isoforms are present in the growth plate chondrocytes, and determined which isoform(s) of PLC is(are) regulated by 1alpha,25(OH)(2)D(3). Inhibitors and activators of PLA(2) were used to assess the inter-relationship between these two phospholipid-signaling pathways. PI-PLC activity in lysates of prehypertrophic and upper hypertrophic zone (growth zone) cells that were incubated with 1alpha,25(OH)(2)D(3), was increased within 30s with peak activity at 1-3 min. PI-PLC activity in resting zone cells was unaffected by 1alpha,25(OH)(2)D(3). 1beta,25(OH)(2)D(3), 24R,25(OH)(2)D(3), actinomycin D and cycloheximide had no effect on PLC in lysates of growth zone cells. Thus, 1alpha,25(OH)(2)D(3) regulation of PI-PLC enzyme activity is stereospecific, cell maturation-dependent, and nongenomic. PLA(2)-activation (mastoparan or melittin) increased PI-PLC activity to the same extent as 1alpha,25(OH)(2)D(3); PLA(2)-inhibition (quinacrine, oleyloxyethylphosphorylcholine (OEPC), or AACOCF(3)) reduced the effect of 1alpha,25(OH)(2)D(3). Neither arachidonic acid (AA) nor its metabolites affected PI-PLC. In contrast, lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE) activated PI-PLC (LPE>LPC). 1alpha,25(OH)(2)D(3) stimulated PI-PLC and PKC activities via Gq; GDPbetaS inhibited activity, but pertussis toxin did not. RT-PCR showed that the cells express PLC-beta1a, PLC-beta1b, PLC-beta3 and PLC-gamma1 mRNA. Antibodies to PLC-beta1 and PLC-beta3 blocked the 1alpha,25(OH)(2)D(3) effect; antibodies to PLC-delta and PLC-gamma did not. Thus, 1alpha,25(OH)(2)D(3) regulates PLC-beta through PLA(2)-dependent production of lysophospholipid.

The effect of whole bee venom on arthritis

This study was performed to assess the clincotherapeutic effect of whole venom of honeybee (Apis mellifera) in adjuvant-induced arthritic rat. Ninety Sprague-Dawley male rats were injected with complete Freund's adjuvant (CFA). Adjuvant arthritis was produced by a single subcutaneous injection of I mg Mycobacterium butyricum suspended in 0.1 ml paraffin oil into the right hind paw. Righting reflex was uniformly lost and considered to be the point of arthritis development on day 14 after CFA injection. The experiments were divided into three groups. When arthritis was developed in the rat, tested groups were administered with prednisolone (10 mg/kg, p.o.) or honeybee venom (one bee, s.c.) every other day for another 14 days. Control group was injected with 0.1 ml of physiological saline solution subcutaneously. Clinical and hematological values with histopathological findings were observed during the drug administration. In treatment groups, the development of inflammatory edema and polyarthritis was suppressed. No significant differences of hind paw edema volume and lameness score between prednisolone and honeybee venom groups were observed during treatment. White blood cell counts of control group showed leucocytosis that was significantly different from the two treatment groups (p < 0.01). Erosions of articular cartilage and inflammatory cell infiltrations into interphalangeal joint were effectively suppressed in treated groups. In conclusion, whole honeybee venom was found to suppress arthritic inflammation in the rat. This may be an alternative treatment of arthritic agony in humans.

Role of melittin-like region within phospholipase A(2)-activating protein in biological function

Phospholipase A(2)-activating protein (PLAA) has been implicated in the production of prostaglandins (e.g. PGE(2)) via activation of phospholipases in various stimulated cell types. Human PLAA, with 738 amino acid (aa) residues, contains a region of 38% homology (aa 503-538) with the 26-aa long melittin peptide, a major component of bee venom and a reported regulator of phospholipase A(2) and phospholipase D activity. To learn more about the role of PLAA in the production of eicosanoids and other inflammatory mediators, we synthesized a murine PLAA peptide (36-aa long) having homology to melittin, as well as to human and rat PLAA. The PLAA peptide and melittin increased the expression of genes encoding the proinflammatory cytokine tumor necrosis factor alpha (TNFalpha) and cyclooxygenase-2 (COX-2), which is involved in PGE(2) production. We determined that the C-terminal region of the PLAA peptide (aa 515-538) was essential, since truncation of the C-terminal end of the PLAA peptide significantly reduced expression of genes encoding TNFalpha and COX-2 in macrophages. We concluded that PLAA could be important in the regulation of the inflammatory response because of its stimulatory effects on eicosanoid and cytokine synthesis. Consequently, control of plaa gene expression could be a target for the development of new drugs to control the inflammatory response.

Bee venom pretreatment has both an antinociceptive and anti-inflammatory effect on carrageenan-induced inflammation

Although the injection of bee venom (BV) has been reported to evoke tonic pain and hyperalgesia, there is conflicting evidence in the literature indicating that BV can also exert an anti-inflammatory and antinociceptive effects on inflammation. In this regard, BV has been traditionally used in Oriental medicine to relieve pain and to treat chronic inflammatory diseases such as rheumatoid arthritis. The present study was designed to test the hypothesis that BV induces acute nociception under normal conditions, but that it can serve as a potent anti-inflammatory and antinociceptive agent in a localized inflammatory state. The experiments were designed to evaluate the effect of BV pretreatment on carrageenan (CR)-induced acute paw edema and thermal hyperalgesia. In addition, spinal cord Fos expression induced by peripheral inflammation was quantitatively analyzed. In normal animals subcutaneous BV injection into the hindlimb was found to slightly increase Fos expression in the spinal cord without producing detectable nociceptive behaviors or hyperalgesia. In contrast pretreatment with BV (0.8 mg/kg) 30 min prior to CR injection suppressed both the paw edema and thermal hyperalgesia evoked by CR. In addition, there was a positive correlation between the percent change in paw volume and the expression of Fos positive neurons in the spinal cord. These results indicate that BV pretreatment has both antinociceptive and anti-inflammatory effects in CR-induced inflammatory pain. These data also suggest that BV administration may be useful in the treatment of the pain and edema associated with chronic inflammatory diseases.

Prostaglandin levels in stimulated macrophages are controlled by phospholipase A2-activating protein and by activation of phospholipase C and D

Prostaglandins (PG), which are responsible for a large array of biological functions in eukaryotic cells, are produced from arachidonic acid by phospholipases and cyclooxygenase enzymes COX-1 and COX-2. We demonstrated that PG levels in cells were partly controlled by a regulatory protein, phospholipase A2 (PLA2)-activating protein (PLAA). Treatment of murine macrophages with lipopolysaccharide, interleukin-1beta, and tumor necrosis factor-alpha increased PLAA levels at early time points (2-30 min), which correlated with an up-regulation in cytosolic PLA2 and PGE2 levels. Both COX-2 and secretory PLA2 were also increased in lipopolysaccharide-stimulated macrophages, however, at later time points of 4-24 h. The role of PLAA in eicosanoid formation in macrophages was confirmed by the use of an antisense plaa oligonucleotide. Within amino acid residues 503-538, PLAA exhibited homology with melittin, and increased PGE(2) production was noted in macrophages stimulated with melittin. In addition to PLA2, we demonstrated that activation of phospholipase C and D significantly controlled PGE2 production. Finally, increased antigen levels of PLAA, COX-2, and phospholipases were demonstrated in biopsy specimens from patients with varying amounts of intestinal mucosal inflammation, which corresponded to increased levels of phospholipase activity. These results could provide a basis for the development of new therapeutic tools to control inflammation.

Bee venom injection into an acupuncture point reduces arthritis associated edema and nociceptive responses

Bee venom (BV) has traditionally been used in Oriental medicine to relieve pain and to treat inflammatory diseases such as rheumatoid arthritis (RA). While several investigators have evaluated the anti-inflammatory effect of BV treatment, the anti-nociceptive effect of BV treatment on inflammatory pain has not been examined. Previous studies in experimental animals suggest that the therapeutic effect of BV on arthritis is dependent on the site of administration. Because of this potential site specificity, the present study was designed to evaluate the anti-nociceptive effect of BV injections into a specific acupoint (Zusanli) compared to a non-acupoint in an animal model of chronic arthritis. Subcutaneous BV treatment (1 mg/kg per day) was found to dramatically inhibit paw edema caused by Freund's adjuvant injection. Furthermore, BV therapy significantly reduced arthritis-induced nociceptive behaviors (i.e. the nociceptive scores for mechanical hyperalgesia and thermal hyperalgesia). These anti-nociceptive/anti-inflammatory effects of BV were observed from 12 days through 21 days post-BV treatment. In addition, BV treatment significantly suppressed adjuvant-induced Fos expression in the lumbar spinal cord at 3 weeks post-adjuvant injection. Finally, injection of BV into the Zusanli acupoint resulted in a significantly greater analgesic effect on arthritic pain as compared to BV injection in to a more distant non-acupoint. The present study demonstrates that BV injection into the Zusanli acupoint has both anti-inflammatory and anti-nociceptive effects on Freund's adjuvant-induced arthritis in rats. These findings raise the possibility that BV acupuncture may be a promising alternative medicine therapy for the long-term treatment of rheumatoid arthritis.

Melittin-mediated release of [3H]-oleic acid from E. coli cells is dependent upon heat- and trypsin-sensitive factor(s) in human serum

Synthetic melittin mediated the release of [3H]-oleic acid ([3H]-OA) or its acylated lipids from [3H]-OA-labeled E. coli cells exposed to human serum. This phenomenon was not observed in the absence of serum and was calcium independent. The addition of serum was not required for melittin-mediated lysis of erythrocytes, although lysis was greater in the presence of serum than in its absence (P<0.001). Trypsin treatment of human serum reduced the melittin-mediated release of [3H]-OA/acylated lipids, and this effect was more pronounced upon boiling the serum (P<0.01). A kinetic study showed that maximum release of [3H]-OA/acylated lipids occurred within 3-6 min. Thin layer chromatography (TLC) analysis showed the lipids to be phosphatidyl ethanolamine (PE), phosphatidylethanol (PEt) and phosphatidic acid (PA). There was no detectable level of oleic acid (OA), diacylglycerol (DAG), phosphatidyl choline (PC) or phosphatidyl serine (PS). These findings suggested that a trypsin and heat-sensitive enzyme/factor present in the serum had a role in melittin-mediated action. These findings further showed that melittin activated phospholipase D (PLD), without affecting phospholipase A(2) (PLA(2)) or phospholipase C (PLC) activity.