| Objective:To investigate the effect of cytoskeletal protein keratin 1 in intestinal inflammation and epithelia tight junction proteins in dextran sulfate sodium (DSS)-induced expermental colitis and methylprednisolone (MP) intervention experiment in mice.Methods:1,DSS-induced expermental colitis model in mice: ①, Thirty-two male C57BL/6 mice were randomly grouped as fellow:control group (n=15), DSS model group (n=17).The colitis model was established by administration of 4% DSS for 7 days. Mice were sacrificed to obtain specimens at 8th day; ②, Colitis was assessed by disease activity index(DAI), weight change, colonic injury/inflammation, colonic length/weight, splenic length/weight and histology score of colonic tissues; ③,The expression of KRT1, claudin-2, occludin and ZO-1 in the colonic mucosa were detected by immunohistochemistry;2, Methylprednisolone intervention experiment:①, Forty-five male C57BL/6 mice were randomly grouped as fellow:control group (n=15), DSS+hydroxypropyl methyl cellulose(HPMC) group (n=15), DSS+MP group (n=15). DSS+HPMC group, DSS+MP group were induced by administration of 3% DSS for 5 days. MP group was given MP (10mg/kg, once a day, dissolved in HPMC) by intragastric administration from 6th day, meanwhile HPMC group was given isodose HPMC, control group was given deionized water. All mice were sacrificed to obtain specimens at 13th day. ②, The indexes of observation and methods of detection are the same as the first part.3, Statistical analysisi: Statistics analysis was performed using SPSS 21.0, and explore the expression correlations between KRT1 and claudin-2, occluding, ZO-1 in colonic mucosa.Results:1, DSS induced expermental colitis model in mice:Compared with that in control group, body weight had significantly loss in DSS model group; DAI score and the macroscopic observation score of colon injure significantly increased (P< 0.01), accompanied with colonic length shortened (P< 0.01), weight decreased (P< 0.05); splenic length increased (P< 0.01), weight increased (P< 0.01); epithelial damage and neutrophil infiltration was showed in colon tissues(P< 0.01); The expressions of KRTI, occludin and ZO-1 protein in colonic mucosa significantly decreased compared with that of control group (P< 0.01), while that of Claudin-2 significantly increased (P<0.01).2, Methylprednisolone intervention experiment:Compared with that in control group, body weight had significantly loss in DSS+HPMC group; DAI score and the macroscopic observation score of colon injure in DSS+HPMC group significantly increased than that in control group(P< 0.01), accompanied with colonic length shortened (P< 0.01), weight increased (P< 0.01); splenic length increased (P< 0.01), weight increased (P< 0.01); epithelial damage and neutrophil infiltration was showed in colon tissues(P< 0.01); The expressions of KRTI, occludin and ZO-1 protein in colonic mucosa significantly decreased compared with that of control group (P< 0.01), while that of Claudin-2 significantly increased (P< 0.01). While with the treatment of MP, mice in the DSS+MP group had significantly greater loss than that in DSS+HPMC group; DAI score and macroscopic observation score of colon injure were significantly decreased (2.17±0.42 vs 2.64±0.48, P< 0.05; 1.23±0.44 vs 2.00±0.77, P< 0.01), the colonic length was shorter (5.73cm±0.50cm vs 5.94cm±0.22cm, p>0.05), weight was decreased(0.32g±0.07g vs 0.38g±0.03g, P> 0.05); splenic length was shorter (1.30cm±0.12cm vs 1.45±0.5cm, P<0.05), weight was decreased (0.063g±0.0012g vs 0.085g±0.023g p< 0.01); The severity of neutrophil infiltration into the mucosa were significantly ameliorated (6.80±1.10 vs 8.00±1.50, P< 0.05); The expressions of KRT1, occludin significantly increased than that of DSS+HPMC group (10.23±1.24 vs 8.64±1.03,8.15±0.90 vs 7.27±0.65,p< 0.01), ZO-1 slightly increased, the difference was not statistically significant (8.15±0.99 vs 7.55±0.82, p>0.05), while the expression of claudin-2 significantly deceased (7.23+0.83 vs 955+1.21, P< 0.01). The expression of KRT1 was positively correlated with the expression of occluding,ZO-1, negatively correlated with Claudin-2 in colonic mucosa, (r=+0.884, r=+0.738, r=-0.837, p<0.01).Conclusions:1, KRT1, Claudin-2, occludin, ZO-1 proteins are involved in the pathogenesis of ulcerative colitis;2, Glucocorticoid not only plays an anti-inflammatory role, but also may regulate the intestinal mucosal barrier function by affecting the expression of cytoskeletal proteins and tight junction in the treatment of ulcerative colitis;3, Cytoskeletal protein KRT1 may paly an important role in maintaining intestinal mucosal barrier function in combination with tight junction proteins. |
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