Influence of Fibroblast Growth Factor-2 on the Activation of Mouse Hippocampal Microglia in a Lipopolysaccharide-Induced Neuroinflammation Model in Vitro

Introduction. Activation of the pro-inflammatory phenotype of microglia may be one of the causes of chronic neuroinflammation and, as a result, can lead to pathological conditions of the brain. The use of neurotrophic factors, such as FGF2, may become one of the promising methods for correcting neurodegenerative diseases, but the question of the influence of this factor on microglia activation is still open. The purpose of this work was to study the effect of FGF2 on the activation of mouse hippocampal microglia in an in vitro model of neuroinflammation induced by lipopolysaccharide. Material and methods. The study was carried out on a culture of primary mixed glial cells of the mouse hippocampus. To quantify, area, and morphological changes in microglial cells in response to the effects of LPS and FGF2, immunocytochemical analysis was performed for markers of astrocytes (GFAP) and microglia (Iba-1). Analysis of the expression level of IL-1β, IL-6, IL-10, TNF-α was carried out by quantitative PCR. Results. In response to LPS exposure, there was an increase in the percentage of Iba-1+ cells, their surface area, changes in morphological characteristics, together with an increase in the level of expression of pro-inflammatory cytokines IL-1β, IL-6, TNF-α and anti-inflammatory cytokine IL-10 both within 6, so 12 hours of exposition. The addition of FGF2 led to a decrease in the percentage of Iba-1+ cells in culture and a decrease in the surface area of microglia. A decrease in the relative level of expression of IL-1β and IL-6 was noted in the groups where LPS and FGF2 were added, while the expression of TNF-α did not change. With an increase in cultivation time up to 12 hours, an increased expression of IL-10 was detected in this group. Conclusion. Stimulation with LPS promotes the transition of microglia from a resting to an activated pro-inflammatory phenotype, as evidenced by increased proliferative activity of Iba-1+ cells in combination with an increase in the level of expression of pro-inflammatory cytokines. Inhibition of two of the three pro-inflammatory cytokines (IL-1β and IL-6) and a significant increase in the level of IL-10 in cell culture suggests an anti-inflammatory effect of FGF2.