Abstract:
Objective:To investigate the effects and mechanisms of receptor-interacting serine-threonine kinase 3 (RIP3) in the formation of cholestatic hepatic injury.
Methods:The experimental study was conducted. (1) Processing and viability of hepatic stellate cell line HSC-T6: HSC-T6 cells were transfected by RIP3-siRNA and NC-siRNA, respectively. The viabilities of un-transfected, RIP3-siRNA-transfected and NC-siRNA-transfected HSC-T6 cells were respectively measured by cell-counting kit-8 (CCK-8). HSC-T6 cells were treated by 100 μmol/L Glycochenodeoxycholic acid (GCDCA) at 0, 2, 4, 8 and 12 hours, and then were extracted and stored, 12-hour cell viability was measured by CCK-8. RIP3 that was treated by 100 μmol/L GCDCA knocked down HSC-T6 cells to establishment RIP3 knockdown HSC-T6 cells (RIP3-KD cells). RIP3-KD cells were cultured for 12 hours, and cell viability was measured. (2) Mice model of bile duct ligation (BDL): 40 adult mice were randomly divided into 8 groups, 5 mice in each group. Sham group: bravery manager was only separated, without ligation, and bloods of inferior vena cava and liver tissues were extracted at 7 days postoperatively. The BDL-1, -3, -5, -7, -14, -21 and -28 d groups: bloods of inferior vena cava and liver tissues were extracted at 1, 3, 5, 7, 14, 21 and 28 days postoperatively, respectively. (3) The relative expressions of RIP3, α-SMA and TNF-α mRNA in the cells and liver tissues were detected by quantitative real-time polymerase chain reaction (RT-PCR). (4) The relative expressions of RIP3, α-SMA and TNF-α proteins were detected by Western blot. Measurement data with normal distribution were represented as ±s. The ANOVA was used for data analysis in different time gradient. Comparisons among groups were analyzed using the ANOVA. Pairwise comparison was done by the t test.
Results: (1) The HSC-T6 cells viability and expressions of RIP3, α-SMA, TNF-α mRNA and proteins: results of CCK8 test showed that 12-hour viabilities of GCDCA-treated HSC-T6 cells, GCDCA-treated RIP3-KD cells, HSC-T6 cells and RIP3-KD cells were 61.3%±0.3% and 83.2%±0.4% and 98.4%±0.7% and 97.4%±0.7% respectively, showing statistically significant differences in the viabilities among them (F=115.200, P<0.05), and showing no statistically significant difference in the viabilities between HSC-T6 cells and RIP3-KD cells (t=1.283, P>0.05). There were statistically significant differences in the viabilities between HSC-T6 cells and GCDCA-treated HSC-T6 cells or GCDCA-treated RIP3-KD cells (t=17.910, 6.604, P<0.05) and between GCDCA-treated HSC-T6 cells and GCDCA-treated RIP3-KD cells (t=7.186, P<0.05). Results of RT-PCR test showed relative expressions of RIP3 mRNA in un-transfected, RIP3-siRNA-transfected and NC-siRNA-transfected HSC-T6 cells were respectively 0.012 1±0.001 3, 0.011 2±0.003 1 and 0.002 8±0.000 5, with a statistically significant difference (F=20.410, P<0.05). There was no statistically significant difference in relative expressions of RIP3 mRNA between un-transfected and NC-siRNA-transfected HSC-T6 cells (t=0.483, P>0.05). The relative expression of RIP3 mRNA in RIP3-siRNA-transfected HSC-T6 cells was significant different from that in un-transfected and NC-siRNA-transfected HSC-T6 cells (t=11.760, 4.586, P<0.05). The relative expressions of RIP3 mRNA, α-SMA mRNA and TNF-α mRNA in GCDCA-treated HSC-T6 cells at 0, 2, 4, 8 and 12 hours were 0.012 1±0.001 3, 0.011 2±0.003 1, 0.021 2±0.002 2, 0.027 8±0.002 1, 0.029 8±0.002 3 and 0.571±0.012, 0.611±0.024, 0.691±0.021, 0.711±0.021, 0.752±0.031 and 0.873±0.022, 0.912±0.024, 1.015±0.031, 1.210±0.042, 1.471±0.041, respectively, showing an increased trend over time and statistically significant differences (F=70.720, 30.050, 166.700, P<0.05). The relative expressions of RIP3 mRNA in HSC-T6 cells and GCDCA-treated HSC-T6 cells were 0.012 1±0.001 3 and 0.029 8±0.002 3, with a statistically significant difference (t=13.970, P<0.05). Results of Western blot showed that relative expressions of RIP3 protein in un-transfected, RIP3-siRNA-transfected and NC-siRNA-transfected HSC-T6 cells were respectively 0.054±0.012, 0.013±0.008 and 0.052±0.021, with a statistically significant difference (F=7.410, P<0.05). There was no statistically significant difference in relative expressions of RIP3 protein between un-transfected and NC-siRNA-transfected HSC-T6 cells (t=0.143, P>0.05), and statistically significant differences were found in relative expressions of RIP3 protein between RIP3-siRNA-transfected HSC-T6 cells and un-transfected or NC-siRNA-transfected HSC-T6 cells (t=4.924, 3.006, P<0.05). The relative expressions of RIP3, α-SMA and TNF-α proteins in GCDCA-treated HSC-T6 cells at 0, 2, 4, 8 and 12 hours were 0.045±0.024, 0.047±0.034, 0.062±0.025, 0.121±0.015, 0.154±0.034 and 0.064±0.031, 0.072±0.017, 0.097±0.035, 0.078±0.031, 0.254±0.051 and 0.078±0.025, 0.094±0.037, 0.129±0.041, 0.198±0.011, 0.324±0.061, respectively, showing an increased trend over time and statistically significant differences (F=9.658, 15.810, 20.090, P<0.05). The relative expressions of RIP3 protein in HSC-T6 cells and GCDCA-treated HSC-T6 cells at 12 hours were 0.045±0.024 and 0.154±0.034, with a statistically significant difference (t=4.536, P<0.05). (2) Expressions of RIP3, α-SMA and TNF-α mRNA in hepatic tissues of mice in each group: the results of RT-PCR showed that relative expressions of RIP3 mRNA, α-SMA mRNA and TNF-α mRNA in the Sham, BDL-1 d, BDL-3 d, BDL-5 d, BDL-7 d, BDL-14 d, BDL-21 d, BDL-28 d groups were 0.047 3±0.003 1, 0.041 2±0.007 8-0.339 7±0.017 1 and 2.948±0.612, 2.654±1.032-8.387±0.910 and 0.563±0.078, 0.610±0.113-1.078±0.289, respectively, with statistically significant differences (F=25.180, 27.820, 7.425, P<0.05). The results of western blot showed that relative expressions of RIP3, α-SMA and TNF-α proteins in Sham, BDL-1 d, BDL-3 d, BDL-5 d, BDL-7 d, BDL-14 d, BDL-21 d, BDL-28 d groups were 0.245±0.011, 0.228±0.023-1.018±0.052 and 0.424±0.057, 0.392±0.041-0.985±0.081 and 0.551±0.052, 0.588±0.087-0.962±0.074, respectively, with statistically significant differences (F=19.160, 94.410, 22.750, P<0.05).
Conclusions:Cholestasis promotes hepatic injury and fibrosis by inducing TNF-α pathway activation and up-regulation RIP3.