Crosstalk between ESKAPE bacteria and NK cells: mutual regulation and role in developing reproductive tract pathologies

Abstract

Natural killer (NK) cells represent one of the innate lymphoid cell subsets, which are often studied in the context of antitumor and antiviral immunity, as well as due to their localization in the zone of the mother-fetus contact (in the uterus), therefore underlying their extensive investigation in developing pregnancy. At the same time, their role in antibacterial immune response has been poorly examined. Because NK cells can produce cytokines, one of putative options for their participation in eliminating prokaryotic pathogens may be coupled to regulation of immune system cells such as dendritic cells, macrophages, etc. However, there have been also described variants of contact cytolysis of cells infected with intracellular bacteria enabled due to cytotoxic proteins perforin, granzymes, granulisin found in NK cells. In recent years, it has become known that NK cells take part in development of immune response against extracellular bacteria including the ESKAPE group bacteria, which includes opportunistic prokaryotes that most actively develop antibiotic resistance and cause nosocomial infections. Here, we attempted to review the data on the role NK cells play in antibacterial immunity. Assessing a crosstalk between ESKAPE group bacteria and NK cells also attracts researchers due to the ability of prokaryotes to alter functions of immune cells, but very little is known about the effects they exert on NK cells. At the same time, such data could be applied to seek out for new ways to treat oncological diseases as well as pave the basis for new approaches to regulating NK cell characteristics in reproductive pathologies. As mentioned earlier, the latter occur in the decidual membrane, where they can interact with fetal cells including trophoblast cells. It is believed that cells can mutually regulate each others properties necessary for the course of physiological pregnancy. Probably, imbalance in this system can lead to development of reproductive pathologies. The review summarizes the currently available data on the effects of ESKAPE group bacteria on NK cells, and also considers putative mechanisms for emergence of impaired interaction between NK cells and trophoblasts exposed to ESKAPE group bacteria. Owing to few publications available on this phenomenon, the experimental study assessing an impact of ESKAPE group bacteria on NK cell properties is envisioned as a necessary stage in development of contemporary biology.