The Influence of Bee Venom Melittin on the Functioning of the Immune System and the Contractile Activity of the Insect Heart—A Preliminary Study

Abstract

Melittin (MEL) is a basic polypeptide originally purified from honeybee venom. MEL exhibits a broad spectrum of biological activity. However, almost all studies on MEL activity have been carried out on vertebrate models or cell lines. Recently, due to cheap breeding and the possibility of extrapolating the results of the research to vertebrates, insects have been used for various bioassays and comparative physiological studies. For these reasons, it is valuable to examine the influence of melittin on insect physiology. Here, for the first time, we report the immunotropic and cardiotropic effects of melittin on the beetle Tenebrio molitor as a model insect. After melittin injection at 10−7 M and 10−3 M, the number of apoptotic cells in the haemolymph increased in a dose-dependent manner. The pro-apoptotic action of MEL was likely compensated by increasing the total number of haemocytes. However, the injection of MEL did not cause any changes in the percent of phagocytic haemocytes or in the phenoloxidase activity. In an in vitro bioassay with a semi-isolated Tenebrio heart, MEL induced a slight chronotropic-positive effect only at a higher concentration (10−4 M). Preliminary results indicated that melittin exerts pleiotropic effects on the functioning of the immune system and the endogenous contractile activity of the heart. Some of the induced responses in T. molitor resemble the reactions observed in vertebrate models. Therefore, the T. molitor beetle may be a convenient invertebrate model organism for comparative physiological studies and for the identification of new properties and mechanisms of action of melittin and related compounds.

Characterization of Gromphadorhina coquereliana hemolymph under cold stress

“…The circulating hemocyte count was determined based on a modified method described previously 53 , 54 . The obtained suspension of hemocytes was examined using a Bürker chamber (Waldemar Knittel Glasbearbeitungs- GmbH, Braunschweig, Germany) and a Nikon PrimoStar light microscope (Nikon, Tokyo, Japan).…”

Synergies with and Resistance to Membrane-Active Peptides

“…In an interesting paradox, MAPs often plan an inhibitory role with respect to the host immune response. Certain MAPs are noted for their ability to impact common immune pathways involved inflammation [50,51]. Notably, MAPs have been shown to increase levels of interferon gamma (INF-γ), interleukin 10 (IL-10), and to reduce levels of tumor necrosis factor alpha (TFN-α) [52].…”

Arthropod Venom Components and Their Potential Usage

“…Crude venom and isolated components were reexamined in a review dealing with the potential therapeutic applications of bee venom to treat skin diseases [13], and in three different research articles dealing with bee venom peptides, melittin and tertiapin, from the view of immunology, molecular neurobiology and physiology. Indeed, Lubawy and collaborators studied the immunotropic and cardiotropic effects of melittin on the physiology of beetle Tenebrio molitor [14], while Choi and coworkers investigated the use of melittin as an analgesic to treat peripheral neuropathy caused by oxaliplatin (an anticancer drug), demonstrating the molecular basis of this particular melittin effect, which was mediated by the activation of the spinal α1and α2-adrenergic receptors [15]. In another work, the Kir channel subtypes of the small hive beetle Aethina tumida were identified by Doupnik [16] as molecular targets of the bee venom peptide tertiapin, based on structure-guided virtual screening methods.…”