Expression of ubiquitin editing enzyme A20 and its pathway in steatotic hepatocytes and monocytes / 中华消化杂志

ABSTRACT

Objective To investigate the changes of A20 expression stimulated by free fatty acids (FFA) and its pathway.Methods HepG2 cells and U937 cells were stimulated by 0.5 mmol/L mixed FFA.The expression of A20,phosphor-p65 and phosphor-IκBα of neclear factor (NF)-κB pathway and phosphor-c-Jun N-terminal kinase (JNK),JNK,phosphor-extracellular signal-regulated kinase (ERK),ERK,phosphor-p38 and p38 of mitogen-activated protein kinase (MAPK) pathway were detected by Western blotting.The level of interleukin (IL)-12p,IL-1β,tumor necrosis factor (TNF)-α,IL-6,IL-10 and IL-8 cytokines in the supernatant of cell culture were detected by flow cytometry.T-test was performed for statistical analysis.Results The level of A20 changed along with the stimulated time of FFA.NF-κB and MAPK pathways were activated after FFA stimulation.The secretion of IL-6 and IL-8 increased after HepG2 cells stimulated by FFA and both reached peak at 24 hour.Compared with control group,the difference in IL-8 was statistically significant ((423.8 ± 8.9) pg/mL vs (12.4 ± 4.5) pg/mL,t=41.28,P＜0.01).The difference in IL-6 was also statistically significant ((4 082±423.6) pg/mL vs (52.9±29.5) pg/mL,t=9.49,P＜0.01).After U937 cells were stimulated by FFA,the secretion of IL-8 increased compared with control group.And in a certain period of time the secretion was time dependence.The maximum secretion of 24 hours was (200.6±5.7) pg/mL vs (5.0±3.9) pg/mL,and the difference was statistically significant (t=28.16,P＜0.01).IL-10,IL-12p,IL-1β and TNF-α were detected.Both NF-κB pathway and MAPK pathway were detected.Conclusions The in vitro FFA mediated steatotic cell model could induce the expression change of A20 and secretion of inflammatory cytokines.NF-κB and MAPK pathways involved in the response to FFA in HepG2 cells and U937 cells.