Activated Syndecan-1 Shedding Contributes to Mice Colitis Induced by Dextran Sulfate Sodium

Background Syndecan-1(Sdc1) plays important roles in many steps of inflammatory responses. In ulcerative colitis patients, decreased Sdc1 expression was observed and Sdc1 analogue heparin could improve the disease course. A better understanding of how Sdc1 functions in colitis will benefit the disease intervention. Aims To evaluate the role of Sdc1 in dextran sulfate sodium (DSS)-induced colitis. Methods BALB/c mice were grouped randomly into control, DSS, and heparin+DSS. The DSS group was given 4% DSS orally and heparin+DSS group was given 4% DSS with heparin (enoxaparin) subcutaneously, while the control was given distilled water orally. All mice were killed at day 7. Disease activities, histopathological changes, membrane-bound and free Sdc1 level and mRNA expression of Sdc1, IL-1, and IL-10 in colon mucosa were detected. Results Significant colitis was observed in the DSS group, but disease activity index and histological score showed significant lower in the heparin+DSS group than those in the DSS group. Compared to the control group, decreased Sdc1 protein expression was detected in colon mucosa of DSS-induced colitis while Sdc1 ectodomain level in serum was much higher. Inhibited Sdc1 ectodomain shedding was detected in the heparin+DSS group compared to the DSS group. RT-PCR demonstrated that both IL-1 and IL-10 expression were up-regulated in DSS-induced colitis while heparin lessened the up-regulation extent. Conclusions Sdc1 shedding is activated in DSS-induced colitis and heparin, which mimics Sdc1 functions, relieves colitis severity by inhibiting Sdc1 shedding and down-regulating cytokines expression.