[Influence of Chlamydia trachomatis type III secretion system on regulation of cytokine response].

AIM: Develop in vitro model for studying production of cytokines by monocyte cells infected with Chlamydia trachomatis mediated by type III secretion system (TTSS). MATERIALS AND METHODS: Strain C. trachomatis L2/434/Bu was used in the experiments, culture of human monocytes U-937 was infected by this strain. Level of inflammatory cytokines was measured on flow analyzer Bio-Plex 200 (Bio-Rad Laboratories). Low molecular compound LHC-342 which belongs to the class of heterocyclic compounds was used as TTSS inhibitor. RESULTS: 24 hours after the infection with C. trachomatis culture 8 analyzed cytokines are induced in U-937 cells (IL-1beta, IL-4, IL-6, IL-8, IL-10, GM-CSF, IFN-gamma, TNFalpha). The most pronounced increase was observed for IL-8, GM-CSF and IFN-gamma. Introduction of TTSS inhibitor into the culture of infected cells suppressed chlamydia growth, but addition of FeSO4 restored the growth of chlamydiae. And activity associated with translocation of effector TTSS protein IncA to inclusion membrane was suppressed. Under the conditions of the obtained model of TTSS inhibition during intracellular development of C. trachomatis a significant decrease of 2 pro-inflammatory cytokines--IL-6 and IL-1beta--was observed. CONCLUSION: Cytokine response plays a key role in the protective immune response in chlamydia infection but at the same time induces immunopathologic conditions. The data obtained give reasons to assume role of C. trachomatis TTSS in the induction of this component of immune response that requires further detailed studies.

[Target-directed search of anti-virulence drugs].

Modern medicine now encounters with problem of the absence of effective antibacterial drugs, which are able to render therapeutic effect on chronic form of infectious process. Thus, the actual objective is to develop essentially new generation of drugs, on the basis of which should lie identification of new bacterial targets playing key role in process of chronization of infection as well as selection of new physiologically active substances, which are able to render highly specific inhibitory effect on selected target. Solving of this objective is possible during realization of new approaches for search and design of new drugs and, first of all, during usage of bioinformatics methods, which enable to identify new biotargets, select most effective chemical compounds-inhibitors and optimize their pharmacological and pharmacokinetic properties. The most promising bacterial target is secretion systems of pathogenic microorganisms participating in realization of their virulent characteristics and playing major role in transition of infectious process in chronic phase. We performed synthesis of and screening for 80 compounds, which allowed to select a range of inhibitors rendering specific target-directed effect on type 3 secretion system of Chlamydia. Obtained data allow to further assess of biological and therapeutic activity of these compounds on developed models of infectious process in vivo.

[Apoptosis of host cells regulation by Chlamydia].

In a study on the impact of chlamydial infection on host cell apoptosis, C. trachomatis were shown to protect host cell against staurosporin-induced apoptosis only at the middle stage of infection development (at 20 hours post infection), C. pneumoniae--at different stages of its growth cycle (from 2 to 7 day post infection). We found, that C. trachomatis elementary bodies fail to inhibit staurosporin-induced apoptotic stimuli. The clear antiapoptotic effect of cell lysate filtrate, infected with C. trachomatis, was demonstrated by cytometric analysis and luminescent microscopy. Our findings make it possible to use biochemical approach to identification of chlamydial antiapoptotic factors in future. Investigations directed at chlamydial antiapoptotic activities may aim to create the therapies of chronic chlamydial infection.

[The apoptosis-supressing activity of clamydia].

The paper covers data from literature, concerning the influence of bacteria upon apoptosis program of host's cells. The mechanisms of apoptosis induction and suppression, developed by bacteria and directed towards the maintenance of conditions favorable to the infection, are quite varied. These mechanisms are realized via complex interaction between biologically active bacterial molecules and particular targets of signal paths which lead to apoptosis. In intracellular parasitism the apoptosis-suppressing activity of bacteria may be considered to be one of the mechanisms of pathogenic organism's persistence which provide favorable conditions for the development of chronic infections. Infection caused by C. pneumoniae in human fibroblasts has been experimentally demonstrated to protect the cells from spontaneous and induced apoptosis.