Peptides help antibiotics
Meat flies improve antibiotics
Kirill Stasevich, "Science and Life", based on the materials of the RNF press service.
To protect themselves from adverse environmental conditions, bacteria form biofilms – complex colonies on the surface of the substrate, in which bacterial cells are immersed in a special intercellular substance, or matrix. In general, the biofilm behaves as a single organism, and not just as a colony of identical bacteria.
Biofilms are very strong and very resistant to physical and chemical influences, they easily withstand the attack of the immune system and are insensitive to antibiotics (resistance to antibiotics and other drugs can increase by 1000 times).
The cell physiology of bacteria in the biofilm changes, they grow differently, etc., in addition, among them there is a group of cells whose condition changes very much – these are the so-called persistence cells that quickly restore the colony, even if it is severely destroyed by an antibiotic. If we consider that among infectious bacteria that can cause certain diseases, about 80% can form biofilms, it becomes clear why researchers are trying to develop as effective ways as possible to destroy them.
A year ago we wrote about the experiments of the staff of St. Petersburg State University (St. Petersburg State University) and their colleagues from the National Cancer Institute in Genoa - they proposed using substances synthesized by meat fly larvae against bacterial biofilms. It is known where these larvae live and what they eat – they feed on carrion, which by definition is teeming with bacteria; and adult meat flies carry many dangerous infections. Moreover, neither larvae nor adult flies suffer from bacteria.
Insects fight microbes with the help of antimicrobial peptides that appear in response to infection (it should be clarified here that there are a lot of antimicrobial peptides, and they are also in other animals, including humans).
If we take, for example, red-headed blue carrion flies, or blue meat flies (Calliphora vicina), then in their antimicrobial mixture we will see dozens of different proteins belonging to the protein families of defensins, cecropins, diptericins and proline-rich peptides. It is almost impossible to artificially create such a complex combination of molecules, so a mixture of antimicrobial peptides is obtained directly from the hemolymph (blood analogue) of infected larvae of red-headed blue carrion.
Previously, it was shown that antimicrobial peptides of meat flies effectively destroy biofilms. Maybe then, with the help of fly proteins, you can enhance the effect of antibiotics? The researchers treated biofilms of several types of bacteria with antimicrobial peptides with the addition of various antibiotics – and indeed, after such treatment, the bacterial persistence cells became very weak and could no longer effectively restore the biofilm, which could now be easily destroyed with an antibiotic.
The full results of the experiments are published in the journal Infection and Drug Resistance (Chernysh et al., Biofilm infections between Scylla and Charybdis: interplay of host antimicrobial peptides and antibiotics). According to Sergey Chernysh, head of the Laboratory of Biopharmacology and Immunology of insects of St. Petersburg State University and one of the co–authors of the work, several classes of antibiotics together with fly peptides give a pronounced synergistic effect, which even allows you to reduce effective doses of antibiotics - all because the persisting cells become more sensitive to them.
It is quite possible that thanks to meat flies, it will be possible not only to increase the effectiveness of good old antibiotics, but also to create new drugs against infections that previously could not be cured by standard methods.
The work was carried out with the support of the Russian Science Foundation (RNF).
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