To Study The Protective Effect Of Bifidobacteria In Ulcerative Colitis And The Initial Study Of The Immunologic Mechanism Of The Effect

Objective :1.To establish the DSS induced Babl/c mouse ulcerative colitis model and the bifidobacteria prevention and cure model. 2. To study the expression of TLR2,TLR4,NF-κBp65,TNF-αand IL-1 in IECs to determine the potential effects of TLR2 ,TLR4,NF-κBp65 ,TNF-αand IL-1 in UC with or without bifidobacteria administration. 3.To study DCs'effects in UC with or without bifidobacteria administration.Methods :Sixty Babl/c mice were divided randomly into three groups,namely the normal group(N),the DSS induced group(D) and the bifidobacteria given group(B).There are no treatmen with the N group;The group D were given normal sodium for coloclysis for 14 days,and from the 8th day 2% DSS were given for free drink ;And the group B were given coloclysis for bifidobacteria for 14 days ,and from the 8th day 2% DSS were given for free drink .Then the Babl/c mice were put to death and the colonic tissue slice were made for histological changes observation ,the detection of DCs and NF-κBp65; the IECs'total RNA were extracted for the detection of TLR2 ,TLR4,IL-1 and TNF-α;and the total protein was extracted from the IECs for the detection of NF-κBp65.Results : 1. The pathological section demonstrated that the structure of intestinal mucous membrane was damaged and there are ulcer in the intestinal mucous membrane in group D,but in group N and B there no change.The ulcerative colitis model and the bifidobacteria prevention and cure model was successfully made. 2. The RT-PCR presented that the expression of TLR2 in IECs in group D and B are incressed compare with the group N and have statistical significance(p<0.05), also the group B was high than the group D and have statistical significance(p<0.05);The expression of TLR4 in group D was high than group N and B and have statistical significance(p<0.05),but there no difference in group B and N. 3. The result of immunohistochemical stain demonstrated that the expression of NF-κBp65 in group D and B are increased compared with the N group and have statistical significance(p<0.05),also the group B is high than group N and have statistical significance(p<0.05).The result of NF-κB p65 with western blot is accordance with the immunohistochemical stain of NF-κB p65. 4.The expression of IL-1 and TNF-αin IECs in the group D are incressed compare with the group N and B and have statistical significance (p<0.05) ,but in the group B and N there were no significant difference. 5.The results of immunohistochemical stain of DCs demonstrated that in the group D and B there are many DCs,but in the group N there almost no DCs.Conclusion : 1.When the balance in the intestinal tract was destroyed, the intestinal Gram negative bacteria can through the TLR4 trigger the NF-κB route's constant activation in the IECs,finally increased the expression of TNF-αand IL-1 in the IECs,so is the inflammation in intestinal mucous membrane. 2.The bifidobacteria can inhibit the growth of intestinal Gram negative bacteria, simultaneously when the presentation of DCs they may through the TLR2 block NF-κB route,and then blocked the proinflammatory gene (TNF-αand IL-1)expression in IECs,so is the relief of inflammation in the intestinal mucous membrane. 3.DCs have there effects in bifidobacteria's protection of UC.