[The effects of interleukin-1 beta and gamma-quantum braking radiation on mesenchymal progenitor cells]

In murine bone-marrow stromal microenvironment cells and in human multipotent mesenchymal stromal cells (MMSCs), proinflammatory cytokine interleukin-1 beta (IL-1β) serves as a growth factor. In murine bone tissue, IL-1β expression increases in vivo after irradiation. Here, we have presented our evaluation of the effects of exogenous IL-1β on the expression of NF-kB transcription factors in human MMSCs and stromal layer cells of murine long-term bone marrow cultures (LTBMCs). The cytokine signaling pathway was also activated in murine LTBMC by braking electron radiation in doses of 3-12 Gy. The level of expression of genes that code for IL-1β, IL-1β type-I receptor and NF-kB and IKK protein families have been studied at different time points post exposure. In both human and murine stromal cells, exogenous IL-1β led to an increase in the level of expression of its own gene, while levels of expression of NF-kB and IKK gene families were not substantially changed. Nevertheless, in human cells, a significant correlation between levels of expression of IL-1β and all NF-kB family genes was detected. It points to a similarity in IL-1β signal pathways in mesenchymal and hematopoietic cells, where the posttranslational modifications of NF-kB transcription factors play a major role. The irradiation of murine LTBMC resulted in a transient increase in the expression of genes that code NF-kB transcription factors and IL-1β. These results indicate an important role of Rel, Rela, Relb, and Nfkb2 genes in the induction of IL-1β signal pathway in murine stromal cells. An increase in IL-1β expression after the irradiation of stromal cells may be related to both the induction of inflammation due to massive cell death and to a profound stimulation of the expression of this proinflammatory cytokine expression.