melitten and Inflammation

Inflammation is a complex multifactorial process and a hallmark of many inflammatory diseases. Most of the tissue destruction that occurs in these diseases is the result of an aberrant or often uncontrolled immune response. Factors that play an important role in such diseases include pro-inflammatory cytokines, complement, and eicosanoids. This review focuses on eicosanoids and their regulation via phospholipase A2-activating protein, which could be targeted as a new therapeutic tool to control inflammatory diseases.

Topics: Animals; Cyclooxygenase 2; Humans; Inflammation; Isoenzymes; Melitten; Membrane Proteins; Models, Biological; Prostaglandin-Endoperoxide Synthases; Proteins; Signal Transduction; Tumor Necrosis Factor-alpha

Ulcerative colitis (UC) is considered one of the most prevalent inflammatory bowel diseases (IBDs). However, due to the lack of satisfying efficacy of conventional therapies and their side effects, there is still a need for more efficient therapeutic agents. Melittin is a small peptide derived from bee venom, which shows potent anti-inflammatory activity. The present investigation aimed to assess the anti-inflammatory effect of melittin peptide alone and in co-therapy with sulfasalazine as a standard therapy on dextran sulfate sodium (DSS)-induced colitis models.. We used DSS to induce UC in C57BL/6 male mice. We investigated the effect of melittin peptide alone and in combination with sulfasalazine on improving the clinical symptoms among DSS-induced colitis models. Finally, we employed histological investigation to show the therapeutic effect of melittin on attenuating the pathological damage of colon tissue caused due to DSS-induced inflammation in colitis models.. Our findings demonstrated that melittin peptide alone and in combination with sulfasalazine dramatically cured the clinical UC. Moreover, we observed that this peptide almost eliminated the histological damage of colon tissue in colitis, while significantly reducing the inflammation in colon tissue. Meanwhile, our results demonstrated that this peptide had an antioxidant effect through the disruption of the oxidant/antioxidant balance.. All these findings suggest that melittin peptide has an anti-inflammatory effect and can probably be considered a novel therapeutic agent for UC. Furthermore, our results demonstrated that this peptide can enhance the therapeutic effects of conventional therapy while attenuating the adverse effects of conventional agents.

Topics: Animals; Anti-Inflammatory Agents; Colitis; Colitis, Ulcerative; Colon; Dextran Sulfate; Disease Models, Animal; Inflammation; Male; Melitten; Mice; Mice, Inbred C57BL; Sulfasalazine

Topics: Animals; Bee Venoms; Bees; Hydrogen Peroxide; Inflammation; Melitten; Mice; Superoxide Dismutase

Lumbar spinal stenosis (LSS) is defined as spinal canal narrowing, resulting in the compression of the nerves traversing the lower back into the leg. Inflammation is the most common cause of LSS. Elevated iron stores are often associated with chronic inflammation resulting in nerve damage-induced pain. Macrophage polarization to either the M1 (inflammatory) or M2 (anti-inflammatory) type is essential for regulating host defenses and promoting tissue repair. However, the precise role of macrophage polarization in iron release or retention in LSS pathophysiology remains elusive. Melittin, a component of bee venom, modulates iron metabolism-related macrophage polarization and is beneficial in LSS. We treated primary peritoneal macrophages with melittin and assessed macrophage polarization by immunofluorescence staining. Melittin (100 and 250 µg/kg) effects on iron deposition-induced macrophage polarization were also evaluated using immunochemistry, real-time PCR, and flow cytometry in an LSS rat model. Locomotor function was assessed using the Basso-Beattie-Bresnahan (BBB) locomotor rating scale, ladder scoring, and von Frey test for up to 3 weeks. Melittin induced M2 polarization of iron-insulted primary macrophages in vitro and increased the proportion of M2 macrophages in the damaged spinal cord in vivo. Moreover, melittin attenuated iron overload-induced M1 polarization by regulating iron metabolism-related genes in rats with LSS. In conclusion, melittin improves locomotor recovery and stimulates axonal growth following LSS. Additionally, it promotes functional recovery in LSS rat models by regulating macrophage iron metabolism, thereby activating M2 macrophages, suggesting its potential application in LSS treatment.

Topics: Animals; Homeostasis; Inflammation; Iron; Macrophages; Melitten; Rats; Spinal Cord Injuries; Spinal Stenosis

Acute liver failure (ALF) is a fatal clinical syndrome with no special drug. Recent evidence shows that modulation of macrophage to inhibit inflammation may be a promising strategy for ALF treatment. In this study we investigated the potential therapeutic effects of melittin, a major peptide component of bee venom both in mice model of ALF and in LPS-stimulated macrophages in vitro, and elucidated the underlying mechanisms. ALF was induced in mice by intraperitoneal injection of D-galactosamine/LPS. Then the mice were treated with melittin (2, 4, and 8 mg/kg, ip). We showed that melittin treatment markedly improved mortality, attenuated severe symptoms and signs, and alleviated hepatic inflammation in D-galactosamine/LPS-induced ALF mice with the optimal dose being 4 mg/kg. In addition, melittin within the effective doses did not cause significant in vivo toxicity. In LPS-stimulated RAW264.7 macrophages, melittin (0.7 μM) exerted anti-oxidation and anti-inflammation effects. We showed that LPS stimulation promoted aerobic glycolysis of macrophages through increasing glycolytic rate, upregulated the levels of Warburg effect-related enzymes and metabolites including lactate, LDHA, LDH, and GLUT-1, and activated Akt/mTOR/PKM2/HIF-1α signaling. Melittin treatment suppressed M2 isoform of pyruvate kinase (PKM2), thus disrupted the Warburg effect to alleviate inflammation. Molecular docking analysis confirmed that melittin targeted PKM2. In LPS-stimulated RAW264.7 macrophages, knockdown of PKM2 caused similar anti-inflammation effects as melittin did. In D-galactosamine/LPS-induced ALF mice, melittin treatment markedly decreased the expression levels of PKM2 and HIF-1α in liver. This work demonstrates that melittin inhibits macrophage activation-mediated inflammation via inhibition of aerobic glycolysis by targeting PKM2, which highlights a novel strategy of using melittin for ALF treatment.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Galactosamine; Glycolysis; Inflammation; Lipopolysaccharides; Liver Failure, Acute; Male; Melitten; Mice; Mice, Inbred C57BL; Molecular Docking Simulation; Protein Binding; Pyruvate Kinase; RAW 264.7 Cells

Sepsis-related acute kidney injury (AKI) is a worldwide health problem, and its pathogenesis involves multiple pathways. Lipopolysaccharide (LPS) is an endotoxin that induces systemic inflammatory responses. Melittin, a main constituent of bee venom, exerts several biological activities such as antioxidant, anti-inflammatory, and antiapoptotic actions. However, whether melittin protects against endotoxin-induced AKI remains undetermined. Here, we aimed to examine the potential action of melittin on LPS-induced renal injury and explore the mechanisms. We showed that acute renal failure and structural damage after injection of LPS were markedly attenuated by administration of melittin. The peptide also suppressed expression of markers of direct tubular damage in kidneys of the LPS-treated mice. Mechanistically, melittin reduced systemic and renal levels of cytokines and inhibited renal accumulation of immune cells with concomitant suppression of nuclear factor kappa-B pathway. Increased amounts of lipid peroxidation products after LPS treatment were largely decreased by melittin. Additionally, the peptide decreased expression of nicotinamide adenine dinucleotide phosphate oxidase 4 and enhanced nuclear factor erythroid-2-related factor 2-mediated antioxidant defenses. Moreover, melittin inhibited apoptotic and necroptotic cell death after LPS treatment. Lastly, we showed that melittin improved the survival rate of LPS-injected mice. These results suggest that melittin ameliorates endotoxin-induced AKI and mortality through inhibiting inflammation, oxidative injury, and apoptotic and necroptotic death of tubular epithelial cells.

Topics: Acute Kidney Injury; Animals; Anti-Inflammatory Agents; Antioxidants; Apoptosis; Cell Death; Endotoxins; Inflammation; Male; Melitten; Mice; Mice, Inbred C57BL; Oxidative Stress; Protective Agents

Acute pancreatitis is a disease associated with suffering and high lethality. Although the disease mechanism is unclear, phospholipase A2 (PLA2) produced by pancreatic acinar cells is a known pathogenic trigger. Here, we show macrophage membrane-coated nanoparticles with a built-in 'lure and kill' mechanism (denoted 'MΦ-NP(L&K)') for the treatment of acute pancreatitis. MΦ-NP(L&K) are made with polymeric cores wrapped with natural macrophage membrane doped with melittin and MJ-33. The membrane incorporated melittin and MJ-33 function as a PLA2 attractant and a PLA2 inhibitor, respectively. These molecules, together with membrane lipids, work synergistically to lure and kill PLA2 enzymes. These nanoparticles can neutralize PLA2 activity in the sera of mice and human patients with acute pancreatitis in a dose-dependent manner and suppress PLA2-induced inflammatory response accordingly. In mouse models of both mild and severe acute pancreatitis, MΦ-NP(L&K) confer effective protection against disease-associated inflammation, tissue damage and lethality. Overall, this biomimetic nanotherapeutic strategy offers an anti-PLA2 treatment option that might be applicable to a wide range of PLA2-mediated inflammatory disorders.

Topics: Acute Disease; Animals; Cytokines; Disease Models, Animal; Female; Humans; Inflammation; Macrophages; Melitten; Mice; Nanoparticles; Pancreatitis; Phospholipases A2; THP-1 Cells

Melittin is the main effective component of bee venom and has extensive biological functions; however, serious side effects have restricted its clinical application. Preclinical and clinical studies showed that the main adverse events were allergic reaction and pain at the administration site. To decrease the toxicity, we prepared melittin nano-liposomes by encapsulating melittin with poloxamer 188 and explored the inhibitory activities on liver cancer together with biological safety. Here, we showed that melittin nano-liposomes significantly inhibited the survival of hepatocellular carcinoma (HCC) cells in vitro and prominently suppressed the growth of subcutaneous and orthotopic HCC transplantation tumors in vivo. It was important that it induced less inflammation and allergy in mice compared with melittin. Overall, melittin nano-liposomes would have a better application in HCC therapy due to its significant anti-tumor activity and better biological safety.

Topics: Animals; Bees; Capsules; Carcinoma, Hepatocellular; Heterografts; Humans; Hypersensitivity; Inflammation; Liposomes; Liver Neoplasms; Melitten; Mice; Nanoparticles; Poloxamer

The present study was aimed to establish a model of chronic prostatitis in rat with the use of intraprostatic injection of Complete Freund's Adjuvant, and to examine the anti-inflammatory and analgesic effects of melittin on the newly-developed chronic prostatic pain model.. Adult male Sprague-Dawley rats were injected with Complete Freund's Adjuvant (CFA) into the prostate. Twelve days after model rats of the treatment group were injected melittin into the prostate, while those of the control group received sterile saline injection. The nociceptive effects of CFA were evaluated by using a behavior approach (i.e. mechanical pain threshold measurement) on the day of CFA injection and 6, 12, and 18days after CFA injection. After the in-live study was done, the prostate was collected for histological examination of inflammatory cell infiltration. Levels of cyclooxygenase (COX)-2 in prostate and glial fibrillary acidic protein (GFAP) in spinal cord were determined using immunohistochemistry. Rats of the sham control group received intraprostatic injection of sterile saline and were studied using the same methods RESULTS: Intraprostatic CFA injection induced local allodynia that lasted over at least 2 weeks. The pain behavior of rat was associated with increases in inflammatory cell infiltration into the prostate. Levels of COX-2 in prostate and GFAP in spinal cord were also elevated. Treatment with melittin significantly raised pain threshold, decreased inflammatory infiltrates, and suppressed COX-2 and GFAP expression.. Intraprostatic injection of CFA induced neurogenic prostatitis and prostatic pain. The established model will be useful to the study of CP/CPPS pathogenesis. Melittin demonstrated profound anti-inflammatory and analgesic effects on the chronic prostatic pain model, suggesting melittin may hold promise as a novel therapeutic for treatment of CP/CPPS.

Topics: Animals; Chronic Disease; Cyclooxygenase 2; Disease Models, Animal; Freund's Adjuvant; Glial Fibrillary Acidic Protein; Hyperalgesia; Inflammation; Male; Melitten; Pain; Pain Measurement; Pain Threshold; Prostatitis; Rats; Rats, Sprague-Dawley; Spinal Cord

Although potent, proteins often require chemical modification for therapeutic use. Immunogenicity, difficult synthesis, and scale-up of these modifications are all engineering obstacles that stand in the way of expanding the use of these therapeutics. Melittin, a peptide derived from bee venom, has been shown to modulate inflammation. Although potentially therapeutic, the native peptide causes cell lysis and toxicity significantly hindering therapeutic application. Based upon the knowledge of the pore formation mechanism, we examined the toxicity and therapeutic effect of a melittin fusion protein with glutathione-S-transferase. The fusion of melittin and glutathione S-transferase results in diminished toxicity of the peptide and retained anti-inflammatory properties at doses that exceed toxic concentration of native melittin. Our results suggest that fusion proteins, particularly those of glutathione-S-transferase, may be facile modifications to control protein activity.

Topics: Animals; Anti-Inflammatory Agents; Bee Venoms; Cells, Cultured; Glutathione Transferase; Inflammation; Macrophages; Melitten; Mice; Peptides; Recombinant Proteins

Venoms consist of a complex mixture of toxic components that are used by a variety of animal species for defense and predation. Envenomation of mammalian species leads to an acute inflammatory response and can lead to the development of IgE-dependent venom allergy. However, the mechanisms by which the innate immune system detects envenomation and initiates inflammatory and allergic responses to venoms remain largely unknown. Here we show that bee venom is detected by the NOD-like receptor family, pyrin domain-containing 3 inflammasome and can trigger activation of caspase-1 and the subsequent processing and unconventional secretion of the leaderless proinflammatory cytokine IL-1β in macrophages. Whereas activation of the inflammasome by bee venom induces a caspase-1-dependent inflammatory response, characterized by recruitment of neutrophils to the site or envenomation, the inflammasome is dispensable for the allergic response to bee venom. Finally, we find that caspase-1-deficient mice are more susceptible to the noxious effects of bee and snake venoms, suggesting that a caspase-1-dependent immune response can protect against the damaging effects of envenomation.

Topics: Animals; Apoptosis Regulatory Proteins; Blotting, Western; Bone Marrow Cells; CARD Signaling Adaptor Proteins; Carrier Proteins; Caspase 1; Cell Line, Tumor; Cells, Cultured; Crotalid Venoms; Cytoskeletal Proteins; Enzyme Activation; Hypersensitivity; Immunoglobulin E; Inflammasomes; Inflammation; Interleukin-1beta; Macrophages; Mast Cells; Melitten; Mice; Mice, Inbred C57BL; Mice, Knockout; Neutrophils; NLR Family, Pyrin Domain-Containing 3 Protein; Receptors, Interleukin-1; Venoms

The bee venom antimicrobial peptide, melittin, besides showing versatile activity against microorganisms also neutralizes lipopolysaccharide (LPS)-induced proinflammatory responses in macrophage cells. However, how the amino acid sequence of melittin contributes in its anti-inflammatory properties is mostly unknown. To determine the importance of the leucine zipper sequence of melittin in its neutralization of LPS-induced inflammatory responses in macrophages and interaction with LPS, anti-inflammatory properties of melittin and its three analogues and their interactions with LPS were studied in detail. Two of these analogues, namely melittin Mut-1 (MM-1) and melittin Mut-2 (MM-2), possess leucine to alanine substitutions in the single and double heptadic leucine residue(s) of melittin, respectively, whereas the third analogue is a scrambled peptide (Mel-SCR) that contains the amino acid composition of melittin with minor rearrangement in its leucine zipper sequence. Although MM-1 partly inhibited the production of proinflammatory cytokines in RAW 264.7 and rat primary macrophage cells in the presence of LPS, MM-2 and Mel-SCR were negligibly active. A progressive decrease in interaction of melittin with LPS, aggregation in LPS, and dissociation of LPS aggregates with alteration in the leucine zipper sequence of melittin was observed. Furthermore, with alteration in the leucine zipper sequence of melittin, these analogues failed to exhibit cellular responses associated with neutralization of LPS-induced inflammatory responses in macrophage cells by melittin. The data indicated a probable important role of the leucine zipper sequence of melittin in neutralizing LPS-induced proinflammatory responses in macrophage cells as well as in its interaction with LPS.

Topics: Amino Acid Substitution; Animals; Cell Line; Cytokines; Inflammation; Leucine Zippers; Lipopolysaccharides; Macrophages; Melitten; Mice; Mutation, Missense; Rats

Melittin is the main peptide in bee venom and causes both persistent spontaneous nociception and pain hypersensitivity. Our recent studies indicated that both transient receptor potential (TRP) vanilloid receptor 1 (TRPV1) and canonical TRPs (TRPCs) are involved in mediating the melittin-induced activation of different subpopulations of primary nociceptive cells. Here, we further determined whether TRPC channels are involved in melittin-induced inflammatory nociceptive responses in behavioral assays.. The anti-nociceptive and anti-hyperalgesic effects of localized peripheral administration of three doses of the non-selective TRPC antagonist, SKF-96365 (1-{β-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenyl}-1H-imidazole hydrochloride), were evaluated in melittin tests. Pain-related behaviors were rated by counting the number of paw flinches, and measuring paw withdrawal thermal latency (s) and paw withdrawl mechanical threshold (g), over a 1-h time-course.. Localized peripheral SKF-96365 given before melittin prevented, and given after melittin significantly suppressed, the melittin-evoked persistent spontaneous nociception. Pre-blockade and post-suppression of activation of primary nociceptive activity resulted in decreased hypersensitivity to both thermal and mechanical stimuli applied to the primary injury site of the ipsilateral hindpaw, despite dose-effect differences between thermal and mechanical hyperalgesia. However, local administration of SKF-96365 into the contralateral hindpaw had no significant effect on any pain-associated behaviors. In addition, SKF-96365 had no effect on baseline threshold for either thermal or mechanical sensitivity under normal conditions.. Besides TRPV1, SKF-96365-sensitive TRPC channels might also be involved in the pathophysiological processing of melittin-induced inflammatory pain and hypersensitivity. Therapeutically, SKF-96365 is equally effective in preventing primary thermal and mechanical hyperalgesia as well as persistent spontaneous nociception. However, this drug is likely to be more effective in the relief of thermal hyperalgesia than mechanical hyperalgesia when applied 5 min after establishment of primary afferent activation.

Topics: Animals; Calcium Channel Blockers; Chronic Pain; Disease Models, Animal; Ganglia, Spinal; Imidazoles; Inflammation; Inflammation Mediators; Male; Melitten; Nociceptors; Rats; Rats, Sprague-Dawley; TRPC Cation Channels

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.

Topics: Analysis of Variance; Animals; Bee Venoms; Formaldehyde; Inflammation; Male; Melitten; Mice; Motor Activity; Pain; Pain Measurement

To identify the active components of honeybee venom in production of inflammation and pain-related behaviors, five major peptidergic subfractions were separated, purified and identified from the whole honeybee venom. Among them, four active peptidergic components were characterized as apamin, mast-cell degranulating peptide (MCDP), phospholipase A(2) (PLA(2))-related peptide and melittin, respectively. All five subfractions were effective in production of local inflammatory responses (paw edema) in rats although the efficacies were different. Among the five identified subfractions, only MCDP, PLA(2)-related peptide and melittin were able to produce ongoing pain-related behaviors shown as paw flinches, while only apamin and melittin were potent to produce both thermal and mechanical hypersensitivity. As shown in our previous report, melittin was the most potent polypeptide in production of local inflammation as well as ongoing pain and hypersensitivity. To further explore the peripheral mechanisms underlying melittin-induced nociception and hypersensitivity, a single dose of capsazepine, a blocker of thermal nociceptor transient receptor potential vanilloid receptor 1, was treated s.c. prior to or after melittin administration. The results showed that both pre- and post-treatment of capsazepine could significantly prevent and suppress the melittin-induced ongoing nociceptive responses and thermal hypersensitivity, but were without influencing mechanical hypersensitivity. The present results suggest that the naturally occurring peptidergic substances of the whole honeybee venom have various pharmacological potencies to produce local inflammation, nociception and pain hypersensitivity in mammals, and among the five identified reverse-phase high pressure liquid chromatography subfractions (four polypeptides), melittin, a polypeptide occupying over 50% of the whole honeybee venom, plays a central role in production of local inflammation, nociception and hyperalgesia or allodynia following the experimental honeybee's sting. Peripheral transient receptor potential vanilloid receptor 1 is likely to be involved in melittin-produced ongoing pain and heat hyperalgesia, but not mechanical hyperalgesia, in rats.

Topics: Amino Acid Sequence; Animals; Apamin; Bee Venoms; Inflammation; Injections, Subcutaneous; Melitten; Molecular Sequence Data; Pain; Peptides; Rats; Sequence Alignment; Sequence Homology, Amino Acid; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

Recently, we have reported that following s.c. injection of a solution containing the whole bee-venom (BV; Apis mellifera), into one hind paw of a rat, the experimentally produced honeybee's sting, the animal shows altered pain-related behaviors and inflammation relevant to pathological pain state. To see whether melittin, the major (over 50%) toxic component of the BV, is responsible for the above abnormal pain behavioral changes, the present study was designed to investigate the effects of s.c. melittin on either nociceptive behaviors in conscious rats or spinal dorsal horn neuronal responses in anesthetized rats. In the behavioral surveys, s.c. injection of three doses of both melittin (5, 25 and 50 microg) and BV (10, 50 and 100 microg) into the posterior surface of one hind paw of rats produced an immediate tonic nociceptive response displaying as persistent spontaneous paw flinching reflex. Similar to the BV test, the melittin response was also monophasic and dose-dependent in terms of both intensity and time course. As an accompanied consequence, both heat and mechanical hypersensitivity (hyperalgesia and allodynia) and inflammatory responses (paw swelling and plasma extravasation) were induced by s.c. melittin injections. In the electrophysiological recordings, s.c. injection of the same three doses of melittin into the cutaneous receptive field produced an immediate, dose-dependent increase in spontaneous spike discharges of spinal dorsal horn wide-dynamic-range (WDR) neurons which are believed to be responsible for the spinally-organized nociceptive flexion reflex. The melittin-induced ongoing spike responses are similar to the behavioral flinching reflex in terms of both duration and frequency. Furthermore, the responsiveness of the WDR neurons to both heat (42 degrees C, 45 degrees C, 47 degrees C and 49 degrees C) and mechanical (brush, pressure and pinch) stimuli was significantly enhanced by s.c. injection of melittin shown as a leftward shift of the stimulus-response functional curves. Taken together, the present results suggest that melittin, the major toxin of the whole BV, is likely to be responsible for production of the long-term spinal neuronal changes as well as persistent spontaneous nociception, heat/mechanical hypersensitivity and inflammatory responses that are produced by experimental honeybee's sting.

Topics: Animals; Dose-Response Relationship, Drug; Electrophysiology; Hindlimb; Hot Temperature; Inflammation; Male; Melitten; Neurons; Pain; Physical Stimulation; Rats; Rats, Sprague-Dawley; Spinal Cord

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.

Topics: Animals; Cell Line; Cyclooxygenase 2; Dinoprostone; Enzyme Activation; Gene Expression Regulation; Humans; Inflammation; Isoenzymes; Macrophages; Melitten; Membrane Proteins; Mice; Peptide Fragments; Phospholipase D; Phospholipases A; Prostaglandin-Endoperoxide Synthases; Protein Conformation; Proteins; Sequence Homology, Amino Acid; Tumor Necrosis Factor-alpha

Topics: Acetylcholine; Animals; Biological Factors; Bradykinin; Female; Hindlimb; Histamine; Inflammation; Melitten; Nitric Oxide; Rats; Serotonin; Vasoconstriction

The nonspecific (nonallergic) inflammatory activity of melittin, a protein toxin from honeybees, was correlated with specific amino acid sequences. Two different amino acid sequences of melittin were found to contribute to nonspecific inflammatory activities in guinea pig skin. Carboxy terminal peptide sequences of 7--10 amino acids induced immediate inflammatory reactions that reached maximum intensities by 15--30 min, then rapidly dissipated. The amino (N) terminal hydrophobic sequence, although not directly inflammatory, intensified the immediate reaction, causing a severe lesion evident by 2 h and characterized by massive polymorphonuclear leukocyte infiltration. A conceptual model of bee venom-induced inflammation in nonallergic individuals is suggested.

Topics: Amino Acid Sequence; Animals; Bee Venoms; Guinea Pigs; Inflammation; Kinetics; Melitten; Peptide Fragments; Structure-Activity Relationship

Injection into the rat paw of either melittin, its C-terminal dekapeptide, tetralysine or triarginine causes an inflammatory response with melittin having the highest and the last mentioned peptides the lowest activity. The inflammatory action of melittin and the dekapeptide has the following characteristics: 1. it is mainly due to the liberation of histamine, since on both compounds the anti-histaminic diphenhydramine has a pronounced inhibitory effect; 2. di-sodium-cromoglycate inhibits only the inflammatory action of the dekapeptide but has no effect on the activity of melittin. Melittin and its fragment thus liberate histamine via different routes.

Topics: Animals; Arginine; Cromolyn Sodium; Disease Models, Animal; Hindlimb; Histamine Release; Inflammation; Irritants; Lysine; Male; Melitten; Oligopeptides; Peptide Fragments; Rats; Venoms