Influence of new antimicrobial peptides of the medicinal leech <i>Hirudo medicinalis</i> on the functional activity of neutrophil granule proteins

Abstract

BACKGROUND: Resistance of microorganisms caused dangerous to human health infections to traditional antibiotics is a serious problem for healthcare. In this regard, the development of new effective antimicrobial drugs and therapeutic approaches is an urgent task. Antimicrobial peptides (AMPs) are considered a promising alternative to traditional antibiotic in the fight against resistant microorganisms.
 AIM: The aim of this work is to study the effect of new synthesized AMPs of the medicinal leech Hirudo medicinalis (including under conditions of development of oxidative/halogenative stress) on the functional activity of neutrophils granular proteins the main effector cells of the immune system.
 MATERIALS AND METHODS: Myeloperoxidase peroxidase activity was assessed by the rate of o-dianisidine oxidation. Neutrophil elastase activity was determined by the fluorescence method using a specific substrate MeOSuc-AAPV-AMC. Lactoferrin iron-binding activity was assessed spectrophotometrically by the change in absorption of protein solution after addition of Fe3+ salt. Lysozyme activity was determined by the rate of M. lysodeikticus bacterial cells lysis.
 RESULTS: Native AMPs 536_1 and 19347_2 inhibited and 12530 increased myeloperoxidase peroxidase activity, this tendency persisted after these AMPs modification by hypochlorous acid (HOCl). In contrast to the native AMP halogenated AMP 3967_1 acquired the ability to enhance myeloperoxidase enzymatic activity. In the presence of AMP 3967_1 neutrophil elastase amidolytic activity increased insignificantly, while AMP 19347_2 inhibited neutrophil elastase activity. After HOCl modification these AMPs retained their ability to regulate neutrophil elastase activity. Synergistic effects (~20%) against gram-positive bacteria M. lysodeikticus were revealed for combination of lysozyme with AMPs 12530 and 3967_1. Inhibition lysozyme antimicrobial activity was observed in the presence of AMPs 19347_2 and 536_1, however the severity of this effect decreased after AMPs modification by HOCl. After HOCl modification AMP 3967_1 increased, while AMP 12530 on the contrary acquired the ability to inhibit lysozyme mucolytic activity.
 CONCLUSIONS: The use of drugs based on studied AMPs of medicinal leech will have a beneficial effect on the bodys fight against infectious agents due to the antimicrobial action of AMPs themselves. But in addition studied AMPs are capable to modulate the biological activity of own endogenous antimicrobial proteins and peptides: to enhance it, if it is necessary to eliminate pathogen and to inhibit if it necessary to protect against damage to the bodys own tissues.