Effect Of Trans Fatty Acids On Lipid Metabolism In LO2 Cells Based On Lipidomics

Epidemiological and clinical studies found that trans fatty acids(TFA)in the diet increased blood lipid levels,promoted atherosclerosis(AS),and thus induced the production of cardiovascular disease(CVD),so countries had issued corresponding policies to limit the amount of TFA in industrial processed foods.However,there were two sources of TFA,one was industrial source trans fatty acid(I-TFA),and the other was ruminant trans fatty acid(R-TFA).CVD was currently the most significant chronic disease affecting human health and CVD mortality accounted for 50%of all chronic diseases.I-TFA was known to increase the risk of CVD,but the effect of R-TFA on cardiovascular health was not clear.Lipidomics technology was an important method to study lipid metabolism and CVD.Therefore,in the global environment where TFA was restricted,it was necessary to analyze the effects of I-TFA and R-TFA on hepatic lipid metabolism,especially with regard to cardiovascular health,based on lipidomics.It was of great significance to clarify the safety of TFA-containing food and guide a reasonable diet.Therefore,this subject took human normal hepatocytes(LO2 cells)as the experimental object,chose 9t 16:1 and 11 t1 8:1 to represent R-TFA,9t 18:1 to represent I-TFA,and at the same time,it also chose to make trans fatty acid-mixture(TFA-mixture)according to the ratio of these TFA in healthy human blood(HHB),cardiovascular disease human blood(CHB),cow's milk(CM)and hydrogenated soybean oil(HSO).Applied them to LO2 cells and observed their effect on the function of LO2 cells.Based on the technique of lipidomics,investigated their influence on the lipid profile of LO2 cells,and identified differential metabolites by partial least squares discriminant analysis(PLS-DA)and t-test to find differential metabolic pathways,and then verified them,to reveal the effect of TFA on lipid metabolism of LO2 cells and clarify the mechanism.The results of this experiment were as follows:1.By measuring cell survival rate,the relative content of reactive oxygen species(ROS),cell membrane integrity,and changes in triglyceride(TAG)and total cholesterol(TC)content,it was found that both TFA and TFA-mixture had certain damage to LO2 cells,which reduced cell viability and cell membrane integrity,increased the relative content of ROS,TAG and TC.Moreover,the damage effect of 9t18:1 representing I-TFA on the function of LO2 cells was significantly higher than that of 9t16:1 and 11t18:1 representing R-TFA(p<0.05);and the damage effect of CHB and HSO on LO2 cells was also stronger than that of HHB and CM(p<0.05).By measuring the composition and content of fatty acids in cells,it was found that the absorption rate of 9tl8:1,9t16:1 and 11t18:1 in LO2 cells was different,and the absorption rate of 9t18:1 was the highest.In addition,11t18:1 underwent Poxidation reaction and ?9 desaturation reaction in LO2 cells,which was converted into 9t16:1 and 9c11t-CLA respectively;9t16:1 also underwent ?9 desaturation reaction in LO2 cells,which was converted to 11t18:1 first,and further converted to 9c11t-CLA;but these reactions did not occur with 9t18:1.Therefore,it was speculated that the difference in function between TFA of different sources may be due to their different absorption rates and different biotransformations in cells.2.Based on the results of lipidomics analysis,it was found that TFA from different sources and their mixtures acted on LO2 cells at a concentration of 100 ?M for 24 h,the intracellular lipid profile changed significantly,TAG,phospholipid(PL)and oxidized lipids(OL)content increased significantly.The results of multivariate statistical analysis showed that the metabolites that contributed the most difference between the 9t18:1 group and the 11t18:1 group were TAG(16:0/18:2/18:3),TAG(16:1/18:1/16:2)and PI(16:2/18:2);the 9t18:1 group and the 9t16:1 group were PMeOH(14:1/16:1),PE(16:1/18:2)and TAG(18:1/18:1/22:5);the 11t18:1 group and the 9t16:1 group were TAG(18:1/18:1/22;5),PI(16:1/18:2),TAG(18:1/18:2/22:5)and TAG(18:1/18:1/22:6);CHB group and HHB group were RvD1,C20:4 and RvE1;the HSO group and the CM group were 12-HEPE,14-HDHA and PGF2?.In addition,the differential metabolic pathways between them all involve arachidonic acid metabolism.Since various metabolites of the arachidonic acid pathway were closely related to the occurrence of AS,many molecules and receptors in its metabolic pathway could be used as drug targets for the treatment of AS-related diseases,and AS was the main cause of CVD,the follow-up study selected arachidonic acid metabolism pathway to further study the effect of TFA on lipid metabolism of LO2 cells.3.The effect of TFA and TFA-mixture on phospholipase A2 in LO2 cells was measured by western-blot and the relationship between phospholipase A2 and arachidonic acid metabolism pathway was discussed.The results showed that TFA(9t18:1,11t18:1 and 9t16:1)and their mixtures of different ratios(HHB,CHB,HSO and CM)could increase the expression of PLA2 protein expression in LO2 cells to a certain extent.In addition,TFA also activated the arachidonic acid metabolism pathway(COX-2,LOX and CYP450)in LO2 cells,and PLA2 regulated the arachidonic acid metabolism pathway in LO2 cells induced by TFA to a certain extent.However,although different sources of TFA could activate the PLA2-AA metabolic pathway,the specificity of different types of PLA2 is not consistent during their activation of the AA metabolic pathway.