Investigation of the effects of polyunsaturated fatty acids on microglia in the brain by in vitro methods

In this study, it was aimed to determine the effect of omega-6 (Ω-6), omega-3 (Ω-3) which is thought to have an impact on neuroinflammation, and each omega-6/omega-3 ratio on microglia and cytokines released from them. The study was carried out in Ankara Health Sciences University Gulhane Health Sciences Institute Stem Cell laboratory in July 2022. The study is an original in vitro study to elucidate the relationship between mediators released from microglia and different rates of PUFA. Microglia were propagated in Dulbecco's Modification of Eagle's Medium and incubated with 1μg/ml LPS. Eicosapentanoic acid was used as Ω-3 and linoleic acid was used as Ω 6. In total, 6 groups were formed. 1.Group control group [Only dimethyl sulfoxide (DMSO) was added to the cell culture.], 2.Group Ω-3, 3.Group Ω-6, 4.Group; Ω-6:Ω-3=15:1 ratio, 5th Group Ω-6:Ω-3=7:1 ratio, 6th Group Ω-6:Ω-3=2:1 ratio were formed and mixed.Fatty acids were emulsified in DMSO and applied to microglia. Afterward, their viability was measured by performing the thiazolyl blue tetrazolium bromide experiment. The cytokines released from microglia (TNF-α, IL-17. IL-1β, IL-6, IL-4, IL-10) were determined using the ELISA method. After 30 μM fatty acid intervention, less cell viability was observed in the Ω-6 group compared to all other Ω-3-containing PUFA groups (p<0.01). After 10 μM fatty acid application, the highest number of viable cells was detected in the Ω-3 group (p<0.05). TNF-α secretion was found to be significantly lower in all other fatty acid groups (Ω-3, Ω-6, 15/1, 7/1, 2/1 groups) compared to the control group (p<0.01). In the IL-4 ELISA test, IL-4 secretion was found to be higher in the group administered Ω-6 fatty acid alone compared to the other groups (Ω-3, 15/1, 7/1, 2/1) (p<0.05). As a result of 10 ELISA tests, there was less IL-10 secretion from microglia in the 7/1 PUFA application compared to the control group (p<0.05). The group with the lowest IL-6 cytokine secretion was the 2/1 group (p<0.05). and malondialdehyde (MDA) showing lipid oxidation was not found in the group supplemented with Ω-3. According to the study's results, inflammatory cytokine release (TNF-α) was decreased in all PUFA-applied groups compared to the control group. Inflammatory cytokine release (IL-6) increased and decreased the release of anti- v inflammatory cytokine (IL-10). More studies are needed to determine the effect of the change in fatty acid ratios on neuroinflammation and to reach clear evidence.