[REGULATION OF ANTIMICROBIAL PEPTIDE SYNTHESIS IN THE LARVAE OF CALLIPHORA VICINA (DIPTERA, CALLIPHORIDAE): DOSE-DEPENDENT EFFECT OF ECDYSTEROIDS].

Ecdysteroids are multifunctional hormones regulating virtually all morphogenetic processes in insects. Their role in stress and immune response regulation is less known. Here we studied 20-hydroxyecdysone effect on synthesis of the antimicrobial peptides in larvae of Calliphora vicina. An inverse correlation was found between 20-hydroxyecdysone titer and the concentration of antimicrobial peptides in the hemolymph of unaffected and bacteria-immunized insects. High and low doses of 20-hydroxyecdysone, injected simultaneously with bacterial cells, had an opposite effect on antimicrobial peptide synthesis in the diapausing larvae. Morphogenetically effective doses of 20-hydroxyecdysone demonstrated immuno-suppressive activity. Low doses of 20-hydroxyecdysone, on the contrary, moderately stimulated synthesis of the antimicrobial peptides. These data suggest that ecdysteroids are directly involved in regulation of the immune system activity and the final effect is dose-dependent.

[Regulation of proliferation and viability of tumor cells in vitro by alloferon-1 and allostatin-1].

Alloferon-1 (AF) and allostatin-1 (AS) cytotoxic and growth modulating activities have been compared. AF is cationic oligopeptide isolated from the hemolymph of experimentally infected blow fly Calliphora vicina. AS is AF synthetic analog that differs from the parent molecule in two amino acids substituted. It has been shown that both AF and AS have no direct cytotoxic activity in concentrations ranging from 1 x 10(-1) to 10 microg/ml, however, the peptides demonstrated significant effect on tumor cells proliferation in vitro. Both peptides displayed growth modulating activity in mass cell cultures and boosted growth inhibiting activity of doxorubicin in the course of P388D1 cells cloning, although AS potentated doxorubicin cytostatic activity to a greater extent. Similarly, AS boosted anti-clonogenic activity of cyclophosphamide applied in a subthreshold concentration. Experiments with peptide-fluorescein complex have demonstrated that AF and AS belong to the group of cell-penetrating peptides. Moreover, the experiments displayed AF ability to bind with chromosomes.

[Immune system of the blowworm Calliphora vicina (diptera, calliphoridae) as a source of medicines].

Study of mechanisms of cellular and humoral immunity of larvae of the blowworm Calliphora vicina has revealed three groups of pharmacologically active substances perspective for use in medicine--alloferons, allostatins, and antimicrobial peptides. Alloferons--the family of peptides of C. vicina stimulating selectively the cytotoxic activity of natural killers of the evolutionary ancient group of immunocompetent cells playing the key role in the system of mammalian antiviral and antitumor immunity. Alloferons are used in medicine for treatment of herpes-viral infections and viral hepatitis B. Allostatins-synthetic peptides combining structural characteristics of alloferons and some mammalian immunologically active proteins. Allostatins, like alloferons, produce stimulating effects on cytotoxic activity of natural killers and interferon production, but differ from them by pronounced adjuvant properties--the ability to enhance immune recognition of alien antigens. At present, allostatins are used to increase resistance of skin and mucosae to viral infections; in future, they might also find use in immunotherapy of cancer and other diseases. Another protein and peptide group perspective for use in medicine serve as antimicrobial peptides in immune response of larvae C. vicina. The study of the agent containing defensins, cecropins, diptericins, and praline-enriched C. vicina peptides shows the drugs of this type to be of great interest as the tool for treatment and prevention of infections caused by antibiotic-resistant bacteria.

[Neurogenic and septic inductions of synthesis of peptide antibiotics in larvae of Calliphora vicina R.-D. (Diptera: Calliphoridae)].

Synthesis of antimicrobial peptides in diapausing larvae Calliphora vicina can be induced by two different pathways. One pathway is well known in insects and includes recognition of microbial particles by the pattern-recognizing receptors. The other pathway includes perception and transduction of stress signal to immunocompetent cells by neuroendocrine system. This phenomenon consists in stimulation of synthesis of defensins, cecropins, and diptericins under effect of chromic stimulation of mechanoreceptors with ligature applied on the larva head end. Formation of immune response in brain is established to need less than 30 s, after which isolation of the neuroendocrine complex does not eliminate activation of immune response As judging from rate of the neurogenic induction, transduction of the stimulating signal from brain to the immune system cells can be connected with release into hemolymph of biogenic amines or other neurohormones stored preliminarily in the neurohemal organ. The nature of this inductor at present remains unknown, as analysis of role of octopamine, dopamine, and adipokynetic hormone did not reveal stimulating effect on synthesis of bactericidal peptides. Physiological mechanism of this phenomenon is not finally understood, its key links seem to be CNS, hormonal factor of cardial bodies, and system of antimicrobial peptides. Synthesis of antimicrobial peptides is directly regulated by the neuroendocrine system that can produce both stimulating and stress action by reminding in this aspect the known immunoneuroendocrine interrelations in vertebrates. The existence of similar integrating mechanisms in such polar animal kingdom groups which are insects and vertebrates indicate that they are more ancient than this was considered earlier.

[Growth modulating and cytotoxic effects of the peptide from hemolymph of blow fly Calliphora vicina (Diptera, Calliphoridae) in vitro].

Biological activity of alloferon (AF), peptide, consisting of 13 a. a. isolated from hemolymph of experimentally infected blow fly Calliphora vicina was studied. AF in concentrations form 1 x 10(-5) to 250 microg/ml was added into the culture medium of the target cell lines K562, J-96, P388DI, Hep22a and 3T3B-SV40. First two days the peptide in concentrations 1 x 10(-5) and 1 x 10(-3) microg/ml in most cases stimulated the cell proliferative activity and suppressed the cell growth when applied in concentrations 10 and 100 microg/ml. Trend in growth modulating effect was dependent on duration of AF treatment. The peptide did not expressed cytotoxic effect with the exception of destruction of P388D1 cells that was registered after 96 h incubation in the medium initially contained 100 microg/ml AF. Simultaneously, cytotoxic and growth modulating effects of doxorubicin and cytosinarabinoside, as well as hybrid molecules, AF--cytosinarabinoside (cytal) and AF--doxorubicin (doxal) have been studied. Doxorubicin and cytosinarabinoside expressed greater growth inhibition effect compared to the hybrid molecules and AF itself. The results obtained with mass cell cultures were supported by experiments where P388D1 cells clonogenic capacity was tested. Besides, it has been demonstrated that AF rapidly penetrates into cytoplasm of J-96 cells and concentrates mainly into and around the cell nuclei.