Inflammation & Allergy-Drug Targets (v.10, #5)

We are happy to present in this issue of “Inflammation & Allergy - Drug Targets” under the guest editorship of Jean-MarcSabatier a comprehensive series of outstanding articles - from molecules to clinics - of animal venoms with reference toallergic and immunological reactions and treatment options.We are fully aware that allergic or anaphylactic reactions to venoms in European latitudes mainly concerm wasps and bees andpresent only a niche of clinical and immunological research. However, for the Pacific Northwest, Central and Middle America,Asia, and Australia animal/insect venoms have a major implication for transferable diseases. Venoms and the concommitanttransfer of pathogenic bacteria and virus by animal/insect bites often cause chronic or even deadly diseases due to rapidhemolysis, fibrinolysis, necrosis or neuronal disorders.At a time when pharmaceutical companies are having trouble finding new drugs and when biologicals are becoming morecommon, animal venoms could constitute an underexploited source of novel drug candidates. Desintegrins, for example, arelow molecular weight peptides found in animal venoms of many snakes and have been recently used to inhibit cancer cellgrowth, adhesion, migration, invasion and angiogenesis [1, 2]. Furthermore, subcutaneous immunotherapy is the only effectivetreatment for patients who experience severe hymenoptera sting-induced allergic reactions; the treatment improves healthrelatedquality of life, too [3]. It is interesting to know that now clinical application of approved drugs currently exists for themajority of snake venom proteins acting on haemostasis. The molecular diversity and mechanisms underlying animal venomsare at the beginning to be understood. The enormous potential that this resource represents for pharmacological prospects is atthe arising horizon.Biomedical researchers, pharmacologists, clinicians and specialized biologists in animal/insect toxins must combine theirefforts to reveal the active principle of animal/insect venoms in the development of new drugs to treat different disease anddisorders, such as cancer, chronic inflammation or pain.As Editor-In-Chief, I would like to thank the guest editor Jean-Marc Sabatier for his excellent work to bring eminent expertsfrom around the world together and who made it possible to publish this synopsis. I would like to thank them for submitting thepapers which are now published after rigorous peer-reviewing. We also know, that, among leading journals in immunologicalniches, there is a high competition for excellent research papers; so, I also appreciate the firm belief of the authors in the highscientific quality of “Inflammation & Allergy - Drug Targets”. Therefore, we are looking forward for the dissemination ofthese published knowledges, above in those areas in the world where animal/insect venoms concern.

The venoms from a variety of animal species (e.g. scorpions, snakes, spiders, sea anemones, marine cone snails, insects andworms) are rich sources of polypeptide toxins that often target -with high potency and variable specificity- different classes ofion channels. In recent years, a number of research teams have focused their efforts on studying the immunological responses toanimal toxins. Apart from the vaccination viewpoint, the potential value of toxins (and related compounds) asimmunomodulators and chemotherapeutic drugs to treat autoimmune diseases has been investigated, especially for someparticular scorpion and sea anemone peptides acting on voltage-gated K+ channels (Kv1.3 channels), and intermediateconductance Ca2+-activated K+ channels (KCa3.1/IKCa1 channels). Indeed, T-cell lymphocytes reportedly express at theirsurface the Kv1.3 (and KCa3.1/IKCa1) channels that are required for antigen-induced cell activation; the same crucial rolebeing also described for activation of B-cell lymphocytes that produce autoreactive antibodies. Therefore, such blockers -whichhave demonstrated their efficacies in vitro and/or in vivo (animal models)- might be good candidates in the treatment of eitherchronic graft rejection or other specific human diseases such as multiple sclerosis, type 1 diabetes, rheumatoid arthritis,inflammatory myopathy, Crown and Hashimoto diseases, scleroderma, psoriasis, vitiligo, uveitis, erythemateous lupus, to cite afew. This special issue of Inflammation & Allergy - Drug Targets deals not only with the functional aspects of animal toxins,but also with associated immune reactivity in the host, as well as the possibility to use venom molecules or derivatives inchemotherapeutic and prophylactic approaches. The eleven review articles have been written by the most distinguishedtoxinologists or immunologists, all of which have made major contributions in their respective areas of toxin research. Theissue, which helps to better apprehend the complexity and potential of these compounds, finally covers the latest state ofknowledge on (i) the pharmacology and immune properties of animal toxins, (ii) the effects of toxins related to immunereactions and cascades in the host, (iii) the toxins and derivatives as candidate chemotherapeutic drugs, (iv) the prophylacticapproaches to animal venoms and toxins (candidate vaccines), (v) the prospects on management of immunity towards toxins,and (vi) the toxins as immunomodulators, from leads to effective drugs.

Analogs of the Sea Anemone Potassium Channel Blocker ShK for the Treatment of Autoimmune Diseases by Christine Beeton, Michael W. Pennington, Raymond S. Norton (313-321).
CCR7- effector memory T (TEM) lymphocytes are involved in autoimmune diseases such as multiple sclerosis,type 1 diabetes mellitus and rheumatoid arthritis. These cells express Kv1.3 potassium channels that play a major role intheir activation. Blocking these channels preferentially inhibits the activation of CCR7- TEM cells, with little or no effectson CCR7+ naive and central memory T cells. Blockers of lymphocyte Kv1.3 channels therefore show considerablepotential as therapeutics for autoimmune diseases. ShK, a 35-residue polypeptide isolated from the Caribbean seaanemone Stichodactyla helianthus, blocks Kv1.3 channels at picomolar concentrations. Although ShK was effective intreating rats with delayed type hypersensitivity and a model of multiple sclerosis, it lacks selectivity for Kv1.3 channelsover closely-related Kv1 channels. Extensive mutagenesis studies combined with elucidation of the structure of ShK ledto models of ShK docked with the channel. This knowledge was valuable in the development of new ShK analogs withimproved selectivity and increasing stability, which have proven efficacious in preventing and/or treating animal modelsof delayed type hypersensitivity, type 1 diabetes, rheumatoid arthritis, and multiple sclerosis without inducing generalizedimmunosuppression. They are currently undergoing further evaluation as potential immunomodulators for the treatment ofautoimmune diseases.

Therapeutic Potential of Peptide Toxins that Target Ion Channels by Evelyne Beraud, K. George Chandy (322-342).
Traditional healthcare systems in China, India, Greece and the Middle East have for centuries exploitedvenomous creatures as a resource for medicines. This review focuses on one class of pharmacologically active compoundsfrom venom, namely peptide toxins that target ion channels. We highlight their therapeutic potential and the specificchannels they target. The field of therapeutic application is vast, including pain, inflammation, cancer, neurologicaldisorders, cardioprotection, and autoimmune diseases. One of these peptides is in clinical use, and many others are invarious stages of pre-clinical and clinical development.

The Humoral Immune Response Induced by Snake Venom Toxins by Wilmar Dias da Silva, Denise V. Tambourgi (343-357).
This review summarizes the key contributions to our knowledge regarding the immune response induced bysnake venom toxins, focusing particularly on the production of antibodies and their venom-neutralizing effects. We coverthe past and present state of the art of anti-snake venom production, followed by an overview of the venomous snakes andtheir venoms. The toxic properties of relevant snake venom toxins are approached in some details, with particularemphasis on the molecular domains responsible for binding to cells or plasma components in victims. The interactions ofthese domains are also reviewed, particularly the putatively relevant epitopes, along with the immune system and theresulting antibodies. We also review trials aimed at reducing the quantities of non-relevant antibodies in the antivenomsby substituting whole venoms with purified toxins to immunize animals, or the immunogenicity of the heterologousantivenom antibodies by humanizing their molecules.

Immunological Aspects of Scorpion Toxins: Current Status and Perspectives by Balkiss Bouhaouala-Zahar, Rahma Ben Abderrazek, Issam Hmila, Naima Abidi, Serge Muyldermans, Mohamed El Ayeb (358-368).
Significant progress has been made in immunological studies of scorpion toxins and several formats ofantibodies directed against scorpion toxins have been reported. Some of these are commonly used in a specific treatmentagainst envenoming; others are primarily used for immuno-biochemical characterizations. The preparation protocol of theantibody or its fragments can be substantially different from one laboratory to another, which complicates a directcomparison of the potency of the antivenom. The use of immune sera, the total immunoglobulin fraction or Fab and Fab'2fragments as the therapeutic agent is widespread. A number of monoclonal antibodies have also been reported and usedfor engineering of Fv, ScFv or Fab fragments. Recently, a novel antibody format - known as nanobodies - derived fromHCAbs of camelids and selected after phage display shows great potential to provide a more efficient therapy againstscorpion envenoming. Subsequent bispecific derivatives have been designed and their pharmacokinetics have beenstudied.Distinct advantages and disadvantages have been attributed to these equine, murine or camelid antibodies and theirderived fragments. Some fragments are easily amenable into next generation therapeutics after proper manufacturing andprovide an ensured availability of the product to the medical community. Through examples, we will show how thecomparison of the serotherapeutic effectiveness is compromised due to the absence of standardization, on the preparationof immunogens, production processes and / or nature of the products. We will report on recent advances in the field.

Antivenoms for Snakebite Envenomings by Jose Maria Gutierrez, Guillermo Leon, Bruno Lomonte, Yamileth Angulo (369-380).
Animal-derived antivenoms constitute the mainstay in the therapy of snakebite envenoming. Antivenoms aremanufactured by immunizing animals, usually horses, with venoms from a single or several medically-relevant snakespecies. Antivenoms are constituted by either whole IgG molecules or the immunoglobulin fragments F(ab’)2 and Fab,obtained by digestion with pepsin and papain, respectively. Differences in the pharmacokinetics of these active substanceshave pharmacodynamic implications. Novel technological possibilities may improve the quality of antivenoms in thefuture, as well as their microbial safety. Antivenom administration might induce early and late adverse reactions, whosepossible mechanisms are discussed. Owing to the large variety in the composition of snake venoms and to the need todemonstrate neutralization of relevant snake venoms in different countries, a meticulous preclinical and clinicalassessment of antivenom efficacy and safety is required before an antivenom is introduced into clinical application. Theaccessibility of antivenoms in low-income tropical countries is of concern and efforts should be directed at guaranteeingthe access of safe and effective antivenoms at affordable prices and their correct clinical use in these countries.

Immune Response Towards Snake Venoms by Guillermo Leon, Laura Sanchez, Andres Hernandez, Mauren Villalta, Maria Herrera, Alvaro Segura, Ricardo Estrada, Jose Maria Gutierrez (381-398).
The immune response involves a complex repertoire of innate and adaptive responses to foreign agents in theorganism. The present review focuses on the immune response to snake venoms, including those occurring in snakebiteaccidental envenomation, experimental vaccination and animal hyperimmunization for snake antivenom production. Thefollowing aspects are considered: (a) the structural characteristics of snake toxins and their relationship toimmunogenicity, (b) the effects that factors such as administration route, venom dose, type of adjuvant, and individual andspecies characteristics of the immunized animal have on the immune response, (c) the initial venom-inducedinflammatory response, (d) the process by which specific antibodies towards individual toxins are produced, and (e) thetechniques currently used to evaluate the antibody response. Understanding the immune response to snake venoms ishighly relevant for improving antivenom production and for gaining a more complete view of snakebite envenoming.

Venom Peptide Modulators of the Immune System by Marco C. Inserra, Richard J. Lewis (399-410).
Venomous animals produce a diverse range of peptides and small molecules that are of both therapeutic andpharmacologic value. One such animal, the cone snail, produces peptides known as conotoxins, which may be of interestto those studying the mammalian immune system. Conotoxins are a family of venom peptides that display extraordinarydiversity and often exquisite specificity for membrane protein targets, especially voltage and ligand activated ionchannels. Conopeptides are proving to be important pharmacological tools to probe human physiology, with someshowing promise as therapeutics for conditions such as neuropathic pain. The potential of these peptides to interact andmodulate the human immune system has not been investigated despite literature suggesting that conotoxins could bevaluable research tools and potential therapeutics in the area of immunology. Known pharmacological targets ofconopeptides expressed by immunocompetent cells include voltage-gated potassium channel (Kv), voltage-gated calciumchannel (Cav), nicotinic and acetylcholine receptors. In addition, the 5-HT3, GABAB and NMDA receptors that are notconsidered classic immunomodulators may play a secondary role in modulating immune responses. This review highlightsvenom peptides with the potential to act at immunological targets within the mammalian immune system.

From the Stretcher to the Pharmacy’s Shelf: Drug Leads from Medically Important Brazilian Venomous Arachnid Species by Breno Rates, Thiago Verano-Braga, Daniel Moreira Santos, Kenia Pedrosa Nunes, Adriano M.C. Pimenta, Maria Elena De Lima (411-419).
Accidents involving venomous animals have always caught the attention of mankind due to their lethality andother clinical implications. However, since the molecules obtained from animal venoms have been the product of millionsof years of evolutionary process, toxins could be used to probe physiological mechanisms and could serve as leads fordrug development. The present work reviews the state of the art pertaining to venom molecules from Brazilian medicallyimportant arachnid species bearing potential biotechnological applications. Special focus is given to toxins isolated fromthe scorpion Tityus serrulatus and the spiders Phoneutria nigriventer and Lycosa erythrognatha, whose venoms possessmolecules acting as erectile function modulators and as antihypertensive, analgesic, neuroprotective and antimicrobialagents.

Stings by insects of the order Hymenoptera cause systemic, sometimes life threatening allergic reactions in 1 -5% of the population in Europe and North America. Responsible for these reactions is an IgE mediated sensitization toproteins of the venoms injected during the stings of social Hymenoptera species, mainly the honey bee (Apis mellifera),vespids like Vespula sp, Polistes sp. and ants, in southern US and central America Solenopsis invicta and in AustraliaMyrmecia pilosula. The venoms of these insects are composed of low molecular weight substances like biogenic amines, cytotoxic andneurotoxic peptides like melittin, apamin, MCD-peptide and mastoparan, and proteins, mostly enzymes likephospholipase A and hyaluronidase, which are major venom allergens. Immunotherapy with Hymenoptera venoms has been shown to protect 80 to over 95% of patients with a history ofsystemic allergic sting reaction from further systemic reactions after re-stings. The procedure, safety and efficacy of thistreatment and the immune mechanisms involved are discussed. Since ancient times honey bee venom has been used for the treatment of chronic inflammatory disease, especially arthritis.Anti-inflammatory effects of bee venom have been documented in animal experiments. Most clinical studies suggest anantiinflammatory effect as well, but are uncontrolled. The only few controlled studies could not confirm efficacy oftreatment with bee venom so far.

Cnidarians comprise four classes of toxic marine animals: Anthozoa, Cubozoa, Scyphozoa and Hydrozoa. Theyare the largest and probably the oldest phylum of toxic marine animals. Any contact with a cnidarian, especially the boxjellyfish (Chironex fleckeri), can be fatal, but most cnidarians do not possess sufficiently strong venomous apparatus topenetrate the human skin, whereas others rarely come into contact with human beings. Only a small, almost negligiblepercentage of the vast wealth of cnidarian toxins has been studied in detail. Many polypeptide cnidarian toxins areimmunogenic, and cross-reactivity between several jellyfish venoms has been reported. Cnidarians also possesscomponents of innate immunity, and some of those components have been preserved in evolution. On the other hand,cnidarian toxins have already been used for the design of immunotoxins to treat cancer, whereas other cnidarian toxinscan modulate the immune system in mammals, including man. This review will focus on a short overview of cnidariantoxins, on the innate immunity of cnidarians, and on the mode of action of cnidarian toxins which can modulate theimmune system in mammals. Emphasis is palced on those toxins which block voltage activated potassium channels in thecells of the immune system.

Immunological and Toxinological Responses to Jellyfish Stings by James Tibballs, Angel A. Yanagihara, Helen C. Turner, Ken Winkel (438-446).
Just over a century ago, animal responses to injections of jellyfish extracts unveiled the phenomenon ofanaphylaxis. Yet, until very recently, understanding of jellyfish sting toxicity has remained limited. Upon contact,jellyfish stinging cells discharge complex venoms, through thousands of barbed tubules, into the skin resulting in painfuland, potentially, lethal envenomations. This review examines the immunological and toxinological responses to stings byprominent species of jellyfish including Physalia sp. (Portuguese Man-o-War, Blue-bottle), Cubozoan jellyfish includingChironex fleckeri, several Carybdeids including Carybdea arborifera and Alatina moseri, Linuche unguiculta (Thimblejellyfish), a jellyfish responsible for Irukandji syndrome (Carukia barnesi) and Pelagia noctiluca. Jellyfish venoms arecomposed of potent proteinaceous porins (cellular membrane pore-forming toxins), neurotoxic peptides, bioactive lipidsand other small molecules whilst the tubules contain ancient collagens and chitins. We postulate that immunologically,both tubular structural and functional biopolymers as well as venom components can initiate innate, adaptive, as well asimmediate and delayed hypersensitivity reactions that may be amenable to topical anti-inflammatory-immunomodifiertherapy. The current challenge for immunotoxinologists is to deconstruct the actions of venom components to targettherapeutic modalities for sting treatment.