Effects And Mechanism Of HepG2 Cells Induced By Trans Linoleic Acid

TFA in food is divided into two categories: processing sources, such as partially hydrogenated and refined oil, and natural sources, such as ruminant animal products. The main source of Chinese dietary TFA is processed foods, which are rich in t-C18:2 and t-C18:3, but only contain few t-C18:1. Foreign dietary TFA is mainly from the commercial hydrogenated oils, dairy products and meat fat, which mainly contain t-C18:1, while almost don’t contain t-C18:2 and t-C18:3. There are many and mature nutrition evaluation of TFA methods in foreign countries, but they are all aimed at t-C18:1 whose intake is dominant and based on the characteristics of the hydrogenated oil. While Chinese intake of TFA is characterized by t-C18:2 and t-C18:3 and their consumption is relatively less than foreign countries. Thus, the TFA intake nutritional evaluation of Chniese residents in vitro needs to be further studied.In view of the TFA nutritional evaluation in China was little, this research subject studied on the nutritional evaluation in vitro about TFA dietary intake character. Using Hep G2 cell as a cell model to discuss cell oxidative damage and apoptosis induced by 9c-C18:1,9t-C18:1,9c, 12c-C18:2 and 9t, 12t-C18:2 of different concentration. The relationship between trans linoleic acid and atherosclerosis(AS) was also investigated in order to provide theoretical basis. The study is of an important theoretical and social value.Cell viability, the level of intracellular ROS, MDA, SOD, CAT, GSH-Px, Caspase-3、-8、-9, morphological change, Apo-B, TG and T-CHO were measured. Flow cytometry was used to determine cell apoptosis. The expression of genes associated with AS were analyzed by RT-PCR. The main results are showed as followed:9t-C18:1 and 9t, 12t-C18:2 significantly inhibited cell viability, decreased SOD, CAT and GSH-Px activity, but increased ROS production and MDA formation. Above indexes showed that trans linoleic acid could induce Hep G2 cell damage. Oxidative stress may be one of the mechanisms of Hep G2 cell damage induced by trans linoleic acid. There has no significant diferrence of cell damage induced by 9t-C18:1 and 9t, 12t-C18:2(P>0.05). Study on the mechanisms of Hep G2 cell damage induced by trans linoleic acid has a promoting effect on the understanding of the relationship between trans linoleic acid and AS.Caspase inhibitor significantly prevented TFA-induced decreation of cell viability(P<0.05). 9t-C18:1 and 9t, 12t-C18:2 could induce cell apoptosis and Caspase-3、-8、-9 could all be activated in the process. TFA-induced activation of Caspase-3 was completely prevented by both Caspase-8 inhibitor(z-IETD-fmk) and Caspase-9 inhibitor(z-LEHD-fmk), and TFA-induced activation of Caspase-9 was also blocked by Caspase-8 inhibitor(z-IETD-fmk) completely. This suggested that cell apoptosis may be also one of the reactions that trans linoleic acid cause AS. The research of the effects of trans linoleic acid on the Hep G2 cell provided theoretical basis, and supplied a scientific evidence for the mechanism of AS.Trans linoleic acid significantly increased the number of intracellular lipid droplets and the content of Apo-B, TG and T-CHO(P<0.05). The m RNA expression of cholesterol synthesis rate limiting enzyme gene HMGCR was raised, leading to the increase of CHO content. But the m RNA expression of high density lipoprotein receptor(SR-BI), low density lipoprotein receptor(LDLR) and the relier of SR-BI(PI3K/Akt) were decreased, which result in a decrease of HDL-C content, but a increase of LDL-C content. Thus, RCT was affected. The m RNA expression of cellular retinol receptors(RXR) was reduced, which caused the decrease of the PPARα/RXR heterologous dimer formation. Then the activation of the regulator of lipid metabolism(PPARα) on its downstream gene SR-BI was inhibited. By regulating the expression of these genes, trans linoleic acid push the further development of AS.