Aging is the main risk factor for the development of many age-related diseases such as dementia, hypertension, atherosclerosis, cancer, autoimmune and other diseases. Numerous studies show that aging is not a programmed process and that it - along with age-related diseases - can be influenced by external therapeutic approaches. One of these is the modulation or elimination of senescent cells, a type of cells which in response to various stressors stop in the G1 or G2 phase of the cell cycle, express their specific phenotype, and begin to accumulate in the organism as it ages. The field of cellular senescence is a young area of research, so there are many open and unanswered questions regarding the mechanisms of its development as well as the reasons for the accumulation of senescence cells at later ages. Despite these challenges, intensive work is already underway to develop compounds that would show a therapeutic effect through their action on senescence as an increased amount of these cells is directly related to the development of age related diseases. They are divided into two groups: senomorphics, which modulate specific processes in senescent cells, most commonly the senescence-associated secretory phenotype (SASP), and senolytics, which remove senescent cells from the organism by inducing apoptosis. Some of the compounds developed have already entered the clinical phases of research.
In the first part of the dissertation, we used molecular simulations to investigate one of the possible mechanisms responsible for the accumulation of senescent cells, which include components of the immune system. Namely, due to the increased presence of the immune inhibitor complex HLA E/β2m/nonapeptide/NKG2A/CD94 formed between the senescent and natural killer cells or CD8+ cells, senescent cells evade the cytotoxic action of the latter. For a comprehensive treatment of ligand recognition by immune cell receptors, we have also investigated systems contains the activating receptor NKG2C/CD94, which is also present on the mentioned cells of the immune system. For the inhibitory immune complex, we created an atomistic model and identified key interactions for signal transduction. This has provided us with a starting point for the rational design of biochemical and structural studies, as well as for the targeted design of interventions to modulate the inhibitory effect on natural killer cells and CD8+ cells. Similarly, we identified key interactions for signal transduction at the atomic level in the activating immune complex model, providing a starting point for the targeted design of further experiments. Using simulations, we also investigated the effect of mutations of nonapeptides on their binding to HLA E and the transduction of an inhibitory signal, providing guidelines for the design of peptides, peptidomimetics, and small molecules that could prevent the inhibition of the cytotoxic effect of immune cells with the inhibitory receptor NKG2A/CD94.
In the second part of dissertation, we performed a virtual screening using the criterion of structural similarity with selected known senolytics to identify new compounds with senolytic properties. In addition, we also included in the evaluation some molecules selected based on the available data from the literature. The senolytic potential of the selected hit compounds was tested on senescent fibroblasts. For this purpose, a screening assay for finding potential senolytics was developed and validated.
The new acquired knowledge contributed to the fundamental understanding of the regulation and modulation of the number of senescent cells by the components of the immune system, while the discovery of a new molecule with senolytic property provided a new chemical tool useful for the evaluation of cellular senescence as a potential new target for the treatment of age-related diseases.
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