## 4 Discussion  
The action of fluoride is associated with the generation of free radicals and the induction of oxidative stress in cells. The biological effects of a static magnetic field are not fully understood, but more and more attention is being paid to its possible therapeutic activity. Earlier studies proved its protective role for normal cells that had been exposed to the factors that disrupt the redox balance against the induction of oxidative stress and apoptosis [16; 17]. However, the aspects of the static magnetic field action at the molecular level are still not fully known. Since melatonin can attenuate the action of free radicals and regulate the enzymatic antioxidant system, in this study, we focused on the genes that are associated with its activity in cells that had simultaneously been exposed to fluoride and a moderate-strength static magnetic field. It was shown that both chemical and physical factors influence the expression of these genes, while the change in expression induced by fluoride is counteracted by a static magnetic field. The level of the expression of the selected genes whose expression was changed by fluoride under the influence of a static magnetic field is compensated for. This study focused on the changes in cells that are caused by fluoride and a static magnetic field primarily at the transcriptional level. The action of melatonin in cells is associated with its immunomodulatory properties not only by affecting the cells of the immune system, but also by regulating the synthesis of the cytokines [26]. Interleukin 27 is a heterodimeric pleiotropic cytokine with pro- and anti-inflammatory properties, which are mediated by the IL27 receptor, which is composed of two subunits: an alpha subunit and glycoprotein 130. Its opposite effect depends, among others, on the type of cells. As was shown, the alpha subunit of IL27 RA is necessary for the transcriptional activation of _STAT1_ and _STAT3_ (a signal transducer and an activator of transcription) and its expression can promote various types of tumor growth [27; 28]. The possibility of IL27 action on non-hematopoietic cells such as fibroblasts or keratinocytes should also be considered. In some diseases, an increased expression of _IL27 RA_ in fibroblasts has been demonstrated [27]. Moreover, in our experiment, an increase in the expression of the receptor alpha subunit was observed under the influence of fluoride, which activates the expression of the inflammatory cytokines [29]. However, a static magnetic field can regulate cytokine disturbances, as is suggested by the obtained results. In turn, the _NR1D1_ gene encodes the protein that play the role of a transcriptional repressor, which coordinates the circadian rhythm and the metabolic pathways of lipids, glucose and proteins. Modifications in its expression are often seen during the development of various diseases [30]. Hence, equalizing the  
Figure 3: The DNA/RNA oxidative damage marker concentration in the control cells (C), F\({}^{-}\)-treated cells (F), cells that had been exposed to a static magnetic field (SMF) and cells that had simultaneously been exposed to a static magnetic field and F\({}^{-}\) (SMF + F). The results are presented as the mean \(\pm\) SD; statistical significance: * \(p\) < 0.05 vs. \(C\); # \(p\) < 0.05 vs. F.  
expression by a static magnetic field is beneficial and will result in the restoration of its correct function. Another very important gene that is modified by both fluoride and a static magnetic field is _HISTIH2 BD_, which encodes the histone H2B type 1-D. Histones are responsible for nucleosome structure and play a key role in modulating the transcription process, whereas the histones that are present in the cytoplasm or extracellularly may contribute to promoting the inflammatory response of cells [31; 32].