RESUMO
Objective To investigate the expression level of receptor-interacting protein serine threonine kinase (RIP) 3 in macrophages/monocytes activation in autoimmune hepatitis (AIH) and its regulation on inflammatory cytokines.Methods The degree of macrophage infiltration and the expression of RIP3 in liver tissues from patients with AIH or hepatic cysts by double-immunofluorescence.After 24 hours treated with different concentrations (0,1,3,6,10 μg/mL) of lipopolysaccharide (LPS),Necrostatin-1,the specific inhibitor of RIP3 signaling pathway,and 6-thioguanine,the active metabolite of azathioprine,the expression levels of RIP1 (RIP3 upstream signal molecule),RIP3 and mixed-lineage kinase domain-like protein (MLKL,RIP3 downstream substrate) in RAW264.7 macrophages were detected by Western blotting.The expression of macrophage-associated cytokine at mRNA level of each treatment group was determined by real time quantitative polymerase chain reaction (PCR).Student's t test and sum rank test were performed for statistical analysis.Spearman analysis was performed for the correlation analysis.Results Compared with hepatic cysts adjacent liver tissues,the infiltration of CD68 positive macrophages in liver tissue of AIH patients was significantly increased (4.75 ± 0.96 vs 28.86 ± 6.23),and the difference was statistically significant (t =7.80,P＜0.05),and the expression level of RIP3 also was significantly increased (15,11 to 22 vs 0,0 to 1),and the difference was statistically significant (Z=-2.66,P＜0.05).In vitro,compared with those of control group,the expression levels of RIP1,RIP3 and MLKL stimulated by LPS at 0,1,3,6,10 μg/mL were significantly increased,and the differences were statistically significant (t=4.00,4.90,6.40,10.30;3.80,9.30,9.80,9.00;4.90,9.90,9.30 and 7.70;all P＜0.05),and were dose-dependent (r=0.91,0.86 and 0.79,all P＜0.05).Furthermore,compared with those of LPS-stimulated group,the expressions of RIP1,RIP3,MLKL of LPS+Necrostatin-1 group were significantly decreased (0.73±0.11 vs 0.47±0.13,0.60±0.07 vs 0.37 ± 0.05,0.65 ± 0.22 vs 0.38 ± 0.04,respectively),and the differences were statistically significant (t=2.60,4.50 and 2.10,all P＜0.05).And the expressions of interleukin (IL)-1β,IL-6and IL-10 at mRNA levels were also decreased (810.3±200.8 vs 463.7±118.1,1 504.4±482.7 vs 290.4±106.9,1 358.6 ± 559.2 vs 677.8 ± 297.6,respectively),and the differences were statistically significant (t=5.40,12.52,5.70,all P＜0.05).However,the expressions of IL-4 and TGF-β at mRNA levels up-regulated (0.3±0.2 vs 0.6±0.3,0.4±0.1 vs 0.9±0.4,respectively),and the differences were statistically significant (t=4.60 and 6.10,both P＜0.05).Compared with those of the LPS-stimulated group,the expressions of IL-1β,IL-6 and IL-10 at mRNA levels of LPS and 6-thiopurine stimulated group significantly down-regulated (810.3±200.8 vs 283.4±65.5,1 504.4±482.7 vs 354.4±73.8,1 358.6± 559.2 vs 625.6±336.3),and the differences were statistically significant (t=4.30,10.60 and 3.50,all P＜0.05);however,the expressions of IL-4 and TGF-β at mRNA levels significantly up-regulated (0.3±0.2 vs 0.6±0.1 and 0.4±0.1 vs 0.5±0.1),and the differences were statistically significant (t=5.20and 12.50,P＜0.05).Conclusions The regulation effects of 6-thiopurine on RIP3 signaling pathway and related cytokines are similar to those of Necrostatin-1.And the expression of RIP3 signaling protein increasing in activated macrophages of liver tissues from AIH patients is closely related to the regulation of IL-6.The RIP3 mediated inflammatory signaling pathway in macrophage may be involved in the genesis and development of AIH and may be a potential therapeutic target.