Study On The Effect Of JNK Signal Transduction Pathway On TNBS-induced Colitis In Mice

Objective:To establish colitis model with TNBS,detect the levels of MPO and TNF-α,expression of p-JNK and apoptosis of colonic epithelial cells.Using inhibitor of JNK SP600125 and probiotics VSL#3 for interfering with TNBS-induced colitis,to investigate the effects of JNK on TNBS-induced colitis in mice.Methods: BALB/c mice were randomly assigned into 4 groups: control group,TNBS-induced Colitis group,SP600125 group,VSL#3 group.To induce colitis, 2.5mg TNBS solution in 50%ethanol was administered into the colon via catheter.In preventional groups of experimental mice,SP600125(30mg/Kg) was administered intraperitoneally 30 mintues before coloclysis and 24,48,72 hours after it;also VSL#3(2mg/d) was administered orally 2 days before coloclysis for totally 5 days.DAI will be recorded everyday. Mice of each group were sacrificed 3 days after coloclysis.The macroscopic score and histological score in each group were evaluated;the MPO activity in colonic tissue was analyzed by chromometry;the expression of TNF-αwas determined by ELISA;expression of p-JNK was detected by immunohistochemical staining; apoptosis of colonic epithelial cells were detected by TUNEL and the apoptosis index(AI) was obtained.Results:1. The DAI of TNBS-induced colitis group increased compared to control group since the coloclysis, the DAI of SP600125 group and VSL#3 group were lower than that of TNBS-induced colitis group;2. The macroscopic score of TNBS-induced colitis group(5.00±2.27)is higher than that of control group(0.50±0.53),SP600125 group(2.13±1.25) and VSL#3 group(2.501.41)(p＜0.05),but no difference within latter two groups(p＞0.05);3. The histologic score of TNBS-induced colitis group(3.13±0.83) is significantly higher than those of control group(0.63±0.52), SP600125 group (1.380.52) (?)and VSL#3 group(1.880.64)(p＜0.05),but no difference within latter two groups(p＞0.05);4. The MPO activity in colonic tissues of TNBS-induced colitis group(4.31±0.69u/g) was higher than those of control group(1.75±0.21u/g), SP600125 group(1.75±0.21u/g) and VSL#3 group(3.86±0.29u/g) (p＜0.05),but higher inVSL#3 group than that of SP600125 group(p＜0.05);5. The expression TNF-αof TNBS-induced colitis group(211.11±46.73pg/mg) in colonic tissues was higher than those of control group(90.60±24.25pg/mg) and SP600125 group(149.74±41.34pg/mg)(p＜0.05),but not VSL#3 group(187.53±30.64pg/mg) (p＞0.05),no significantly difference within latter two groups(p=0.05);6. The p-JNK IOD of TNBS-induced colitis group(28.06±2.15) in colonic tissues was much higher than those of control group(6.83±1.28) and SP600125 group(13.27±1.47)(p＜0.01),not VSL#3 group(26.32±2.53) (p＞0.05),the IOD of SP600125 group was much lower than that of VSL#3 group(p＜0.01);7. The colonic epithelial cells AI of TNBS-induced colitis group(16.75±1.98) was higher than those of control group(3.38±0.92),SP600125 group(8.88±2.36) and VSL#3 group(13.75±2.71)(p＜0.05). VSL#3 group was higher than that of SP600125 group(p＜0.05);8. There were positive correlations between the MPO activity, the expression of TNF-α, colonic epithelial cells AI and the IOD of p-JNK (r=0.738, r=0.738, r=0.788,p＜0.05).Conclusions: This results suggest that JNK signal transduction pathway was involved in the pathogenesis of TNBS-induced colitis model. Inhibition of JNK signal transduction pathway by SP600125 could ameliorate TNBS-induced colitis, decrease the MPO and TNF-αlevels, reduce the p-JNK expression,inhibit apotosis of colonic epithelial cells. And this model is similar to human CD.SP600125 may be a valuable biotherapy for CD.