| Objective To evaluate the prevention effects of TLR2mAb and TLR4mAb on DSS-induced colitis in mice.Methods Fifty healthy male BALB/c mice (SPF level) purchased from an experimental animal center (Shanghai Medical College, Fudan University, China), all weighing about 25 g, were randomly assigned into five groups:the normal control group (group A), the UC model group (group B), TLR2mAb intervention group (group C), TLR4mAb intervention group (group D) and TLR2mAb+TLR4mAb intervention group (group E). Group B to group E were given 5.0% DSS solution as drinking water for 7 days to induce acute intestinal inflammation while the normal control group drank distilled water freely. Groups C, D and E respectively received TLR2mAb (10μg), TLR4mAb(10μg) and TLR2mAb (10μg)+TLR4mAb(10μg) injection intraperitoneally once on days 1,3,5 and 7. Group A and B received a normal sodium injection intraperitoneally as control. All mice were killed on the eighth day. The daily disease activity index (DAI) assessment was carried out in the process of modeling. The tissues were fixed with 10% neutral formalin, embedded in paraffin for blinded histological analysis. The mucosal mRNA expressions of TLR2 and TLR4 were analyzed by Realtime PCR. Fecal samples were obtained directly from the cecum and were serially diluted in Ringer diluent for incubation under aerobic or anaerobic conditions. After incubation, colonies were identified according to standard procedures.Results (1) The DAI score was the lowest in group A. In group B-E, DAI scores were higher than group A (P<0.01). Group B was the most different from group A. Groups C and D had relatively lower scores than group B, but there were no significant differences between each group (C/D vs B, P>0.05). Group E, with TLR2mAb+TLR4mAb intervention, showed a markedly lower score than group B (P<0.05). Compared with group A, group B showed a significant difference in HS(P<0.01). The inflammation was improved in groups C-E. Although HS seemed to be lower in group C and D than group B, there were no significant differences between each group (P>0.05). Notably, the inflammation was significantly improved in group E with a lower HS than group B (P<0.01). (2) In mice with DSS-induced colitis, expressions of both TLR2 and TLR4 in colonic epithelial cells were much higher than normal mice:group B was notably different from group A (TLR2:P<0.01; TLR4:P<0.05). Intervention with TLR2mAb or/and TLR4mAb could down-regulated their expressions to nearly the normal level (P>0.05). (3) Group A showed a considerable predominance of Lactobacillus spp and Bifidobacterium spp. Comparing with group A, group B showed a conspicuous increase of Escherichia coli and decrease of Lactobacillus spp(P<0.05) and Bifidobacterium spp(P<0.05). After being treated with TLR2mAb and TLR4mAb, Lactobacillus spp and Bifidobacterium spp in groups C, D and E increased noticeably to the normal level, and there was no statistical significance between every intervention groups and the normal control group (P>0.05). While counts of E. coli in group C-E were still nearly the same as that in group B (C/D/E vs B, P>0.05).Conclusion Intervention of TLR2mAb combined with TLR4mAb is effective in suppressing DSS-induced colitis in mice. Both TLR2mAb and TLR4mAb can increase counts of Lactobacillus spp and Bifidobacterium spp in DSS-induced colitis. While these interventions have less influence in reducing the count of E. coli.
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