Investigation On The Construction Of Animal Model Of Inflammatory Bowel Disease And The Therapeutic Efficacy Of Mucosal Tolerance Induced By IL-10 And Probiotic

The Role of Th1/Th2 Lymphocyte in Mice with the Experimental Colitis Induced by 2,4,6-Trinitrobenzene Sulfonic Acid and OxazoloneObjective: To investigate the role of Th cells in 2,4,6-trinitrobenzene sulfonic acid and oxazolone induced murine colitis.Method: The TNBS- induced mice colitis was established by enema intrarectally with TNBS 1 mg,1.5mg,2mg,2.5mg/50% ethanol on day1 and day8. Oxazolone- induced colitis were injected intrarectally 3% or 1% oxazolone. In order to obtain a more long-lived,chronic inflammatory response ,we presensitize mice with 3% oxazolone skin painting 5 days before rectal challenge and 1% oxazolone intrarectally to induce colitis.The clinic and colonic histological change were evaluated.The ratios of Th1/Th2 lymphocyte in lamina propria and spleen were detected by FCM with two color intracellular cytokine staining. Result: Although no mortality was observed in animals treated with 1mg TNBS,higher doses of the haptenizing agent resulted in 6.5%,37.5%,and 62.5% mortality after induction.A severe illness characterized by diarrhea and severe wasting disease was observed in mice treated with 2mg and 2.5mg.Intrarectal administration with 3% oxazolone developed a rapid onset colitis marked by weigh loss and bloody diarrhea peaking by day 2 after oxazolone administration and leading to death of 68.75% of the mice .Presensitized mice administered 1% oxazolone developed colitis marked by sustained weigh loss sometimes culminating in death.Nonpresensitized mice given 1% oxazolone had a slightly weigh loss and no mortality was seen.The acute histologic features of TNBS colitis showed transmural necrosis,erosion,hyperaemia and hemorrhagic,with prominent inflammatory cells infiltration.After the second TNBS treatment,follicle aggregation and regenation was observed.After 3% oxazolone administration 48 hours ,a severe hemorrhagic colitis confined to the distal half of the colon.It consists of a superficial inflammation characterized by the presence of epithelial cell loss and patchy ulceration .In addition,a mixed neutrophil/lymphocyte infiltration was limited to the superficial layer of the mucosa .The submucosal layer displays marked edema with few inflammatory cells,while in the outer muscle layer one sees litter or no evidence of inflammation at all.Histological examination of mouse colon at day 7-10 showed that presensitized mice developed massive bowel wall edema and epithelial cell loss. In lamina propria lymphocyte of murine colonic mucosa from TNBS model , Th1 cell was 8.32±1.07%,significantly higher than that in the control(P<0.05). Th2 cell was 1.91±1.37%,which was of no significant difference compared to that in the control(P>0.05).The ratio of Th1/Th2 was 3.66±1.16,significantly higher than that in the control(P<0.05). In lamina propria lymphocyte of murine colonic lamina propria from oxazolone model , Th2 cell was 9.18±3.07%,significantly higher than that in the control(P<0.05). Th1 cell was 3.02±1.37%,which was of no significant difference compared to that in the control(P>0.05).The ratio of Th1/Th2 was 0.67±0.16,significantly lower than that in the control(P<0.05). Conclusion:TNBS and oxazolone induced colitis was a inflammatory disease characterized by predominant colonic immune disturbance. Th1 response might be involved in TNBS induced colitis,and Th2 response might play an important role in oxazolone colitis.