[Syndecan-1 expression and its significance in colitis]

To explore the effect of syndecan-1 (Sdc-1) in the pathogenesis of colitis.

Thirty BALB/c mice were forced to drink 4% dextran sodium sulphate (DSS) in distilled water as the sole source of drinking fluid for 7 days, distilled water for 10 days, and 4% DSS in distilled water for another 7 days so as to establish colitis models and then were randomly divided into 3 equal groups: model groups 1, 2, and 3 to be killed 8, 18, and 25 days after the DSS drinking respectively to take their colons. Another 10 mice were fed with distilled water as control group and were killed on Day 8. Microscopy was used to evaluate the histological score of the colon. RT-PCR was used to detect the expression of Sdc-1 mRNA and IL-1 mRNA in the colon mucosa. Immunohistochemistry was conducted to detect the Sdc-1 protein level.

The histological scores of the 3 model groups were all significantly higher than that of the control group (F = 448.717, P < 0.01) and the score was the highest in the model group 1 and then gradually decreased. There was not significant differences in the Sdc-1 mRNA expression among different groups (F = 0.822, P > 0.05). The levels of Sdc-1 protein of the 3 model groups were all significantly lower than that of the control group (F = 865.586, P < 0.01), and the Sdc-1 protein level was the lowest level in the model group1, and then increased gradually. The expression of IL-1 mRNA of the 3 model groups were all significantly higher than that of the control group (F = 103.833, P < 0.01), and the IL-1 mRNA level was the highest in the model group1 and then decreased gradually.

The severity of colitis is associated with the reduction of Sdc-1 protein level, but not with the Sdc-1 mRNA level in the colon mucosa. The reduction of Sdc-1 protein level may be associated to increase of IL-1 level.