Multidrug resistance reversal

Ziel

A. BACKGROUND

Many antibiotics have lost their effectiveness in the last decade. Multiple resistance means that patients are ill for longer and they are at a greater risk of dying from infectious diseases.

Attention has been drawn to the decrease in clinical efficacy of well known drugs. This means that the microorganisms as causative agents of the diseases concerned are able to survive the usual dose of chemotherapy.

Resistance to chemotherapeutics has been observed emerging among bacteria, fungi, protozoa, and cancer cells. The basic reason for the development of this resistance is Darwinian selection, which ensures the adaptation of the living cells to changing environment. The genetic basis for drug resistance can be extrachromosomal or chromosomal. The former makes the living organism more flexible in its adaptation to the environmental changes, ensuring the evolution of resistance, while the latter is less frequent by mutations and more conservative than the extrachromosomally encoded one. The development of resistance responsible for the stable inheritance in bacteria, protozoa, and fungi, involves a wide variety of mechanisms.

Plasmids of bacteria encode various functions responsible for multidrug resistance, such as ABC transporters and permeability barriers. One of the ABC transporters of bacteria shows a great degree of homology with the MDR glycoprotein of fungi and cancer cells responsible for multidrug resistance as well.

Multiple resistant bacteria such as Salmonella, Klebsiella, Pseudomonas, Enterobacter species, etc., causing severe infections with high incidences of septicemia have become a major problem in chemotherapy.

There are several quite different mechanisms of resistance although one, at least, seems to be common to bacteria, parasites, fungi and cancer cells. It is usually called as Multidrug Resistance (MDR).

The decrease in drug accumulation has been ascribed to the increased activity of an efflux pump mediated through the action of a P-glycoprotein.

The reversal of this resistance is a promising area of multidisciplinary research, because too few drugs are being developed to replace those which lost their effectiveness through the development of resistance.

The framework of this new Action COST B 16 is based on the experience gained during COST 815. It is obvious from the evaluation of the former COST action, that the COST provides a unique opportunity for this type of collaborative work. Since multidrug resistance imposes the same consequences on the whole of Europe European cooperation is therefore desirable in this topic, as a concerted action.

Consequently, pooling of the various experiences of experts from different fields such as bacteriology, mycology and medicinal chemistry is undoubtedly needed in undertaking this stimulating challenge. Theoretically, resistance reversing compounds can reduce mortality and morbidity from microbial infections.

This novel strategy would be implemented through a project detailed in the already accepted COST B 9 Action (which is focused on parasitology) and this recently submitted COST B 16 proposal, which concentrates on the multiresistant bacteria and resistant fungi.

B. OBJECTIVES AND BENEFITS

The main objective of the Action is to increase the knowledge of the mechanisms of multidrug resistance in bacterial and fungal infections with a view to developing new drugs capable of reversing this drug resistance.

It must be emphasised that no similar multidisciplinary network exists until now.

Drug Research requires cooperation between large and dedicated teams of experts. However, communication between scientists working in well defined fields of drug resistance such as bacteriology and mycology is usually rather poor.

A framework has to be created, which should allow a free flow of scientific results.

Although this field of study involving cellular mechanisms is far from the drug-marketing stage, the expected results will directly affect clinical problems. Due to this, representatives from pharmaceutical companies will be involved in the management of the Action with a view to evaluating and developing of the results as soon as possible.

At this stage, two associated members from Pharmaceutical Companies are interested in taking part in the Action.

C. SCIENTIFIC PROGRAMME

The scientific Programme of the proposed COST Action is specifically devoted to the reversal of resistance in bacterial and fungal cells via inhibition of the drug efflux mechanism which is managed by a transmembrane protein.

The synthesis of this glycoprotein is under the control of a gene so that targets for drugs capable of reversing the resistance could be either at the protein or the nucleic acid level, and the mechanism of action of active drugs has to be investigated at both levels.
At the present time, the structures of active compounds, known as chemo-sensitizers, strongly differ from one to another. Thus, the first research theme will be devoted to the investigation of Structure-Activity relationships in this field.

A possible mechanism for the inhibition of the multidrug resistance efflux pump could be the formation of a complex between ligand and a regulatory active site. Thus, the interaction between drugs and sites will be studied using flow cytometry, fluorescence spectroscopy, UV spectroscopy, 2D nuclear magnetic resonance spectroscopy, and thermal denaturation techniques. The results will be modelled using molecular graphics with the aim of designing highly specific ligands by defining new strategies for resistance reversal.

It can also be emphasised that Pdr5 and related yeast drug transporters serve as useful paradigms to study the molecular determinants of substrate specificity of both endogenous and heterologous ABC transporters. These are associated with multidrug resistance, because of the structural and functional homology of the yeast and mammalian P-glycoproteins. Studies on the yeast ABC efflux pump will include (i) the analysis of their biogenesis, (ii) the proteolytic turnover and intra-cellular trafficking, (iii) a detailed molecular genetic function analysis, and (iv) the biochemical purification and functional reconstitution in proteoliposomes in vitro.

P-glycoprotein sequences of multidrug resistant cancer cells have a substantial degree of sequence similarity with a family of bacterial transporter proteins, e.g. RTX exotoxins. On the basis of this homology, the consequences of plasmid elimination and multidrug resistance efflux inhibition will be compared on bacteria and tumor cells. Antiplasmid activity of newly synthesised ligands on plasmid DNA, plasmid replication, partition, and on the conjugational transfer will be examined.

Our aim will be the synthesis of drugs active against multidrug resistance of bacteria and fungi.

This will be achieved by the following way:

1)Search for new reversal agents using in vitro models. Novel lead structures could be developed by COST partners in working groups.

2)Preliminary in vivo investigation of resistance reversion by drug in synergistic combination with the resistance modifying agents and anti-bacterial, or antifungal drugs in animal experiments. Animal experiments will be carried out within the framework of the basic rules and corresponding laws for animal experimentation.

3)Research into the mechanism(s) of action will be carried out
a)at the gene level,
b)at the efflux pump activity level.

4)Study of the ligand site interactions by using biochemical assays, molecular modelling, and competition with known substrates.

Experts have been involved in the preparation of the Action but the Scientific Programme will be defined in detail by the Management Committee of the Action.
However, the multidisciplinary research will require the setting up of three Working Groups (WG) to carry out specific research programmes on the fields of bacteriology, mycology and medicinal chemistry. Organization will be given in the following paragraph D.

D. ORGANIZATION AND TIMETABLE

The proposed duration of the Action is 5 years.

Owing to the multidisciplinary content of the proposed Action, research will be carried out by several WG which will be under the responsibility of a coordinator in bacteriology, mycology and medicinal chemistry.

The Management Committee will control the reporting of the results, evaluate the performance of the working groups, set priorities and propose new lines in the field of the Action.

Within the frame of these projects, short missions of scientists, PhD students and technicians are planned in order to favour cooperation and to stimulate technological exchanges.

Meetings for WG workshops will be organised at least one per year. Documents ensuing from these workshops will be prepared in such a way that they can be distributed as reference documents for all the Partners involved in the Action.

These Annual Meetings will give the opportunity to all working groups, members of COST B 9 and other Scientists who are not involved directly in the Action to meet and to present papers. In doing so new Partners will be also subsequently selected for participation in the Action. Moreover, cooperation with COST B 9 will be encouraged. Specialists from Non-European countries will be invited to these conferences as well.

The following plans are proposed for dissemination of the results of the Action to a wider audience.

-One open Meeting per year, (with oral communications and posters) are planned.

-At least one internal workshop per year organised by each WG specifically devoted to selected topics.

-Short term scientific missions.

Based on the presentations at annual open Meetings conference proceedings will be prepared by the conference organising committee and distributed for the participants.

The main results will be disseminated as news letters according to the decision of the 1st Management Committee Meeting for the Laboratories who are already involved in the list of contributors and also the other selected scientists recommended by the contributors.

Since a large number of scientists work on this area all over the world (not only in EU countries) we plan to initiate a new international journal in the field to publish and distribute the results for other scientists.

E. ECONOMIC DIMENSION

The following COST countries have actively participated in the preparation of the Action or otherwise indicated their interest: Austria, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Poland, Romania, Spain, Switzerland, United Kingdom.

On the basis of national estimates provided by the representatives of these countries and taking into account the coordination costs to be covered over the COST budget of the European Commission, the overall cost of the activities to be carried out under the Action has been estimated, in accordance with 1998 prices, at EUR 12,5 million.

This estimate is valid assuming that all the countries mentioned above participate in the Action. Any departure from this will change the total cost accordingly.

Finally annual Open Meetings will be organised on a rolling schedule by partners.

Programm/Programme

IC-COST - European cooperation in the field of scientific and technical research (COST), 1971-

Thema/Themen

7 - Medical Research

Aufforderung zur Vorschlagseinreichung

Data not available

Finanzierungsplan

Data not available

Koordinator

N/A

EU-Beitrag

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Adresse

Ungarn

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