Downregulation of Dickkopf-1 Augments the Therapeutic Effects of Endometrial Regenerative Cells on Experimental Colitis

Abstract Background We have demonstrated that endometrial regenerative cells (ERCs) are mesenchymal-like stromal cells and can attenuate experimental colitis, however, its underlying mechanism needs further investigation. Dickkopf-1 (DKK1), a glucoprotein secreted by mesenchymal stromal cells (MSCs), is a classical inhibitor of Wnt/β-catenin pathway which is closely associated with the development of colitis. Therefore, the objective of this study was to investigate whether ERCs could also secret DKK1, and whether the downregulation of DKK1 (DKK1 low -ERCs) would enhance the therapeutic effects of ERCs in attenuation of experimental colitis. Methods BALB/c mice were given 3% dextran sodium sulfate (DSS) for 7 consecutive days and free tap water for 3 days sequentially to induce experimental colitis. Unmodified ERCs, IL-1β-treated ERCs (DKK1 low -ERCs) and glucocorticoid-treated ERCs (DKK1 high -ERCs) were injected (1 million/mouse/day, i.v. ) on day 2, 5 and 8 respectively. Colonic and splenic samples were harvested on day 10 after DSS-induction. Results It was found that DKK1 low -ERC treatment markedly attenuated colonic damage, body weight loss and colon-length shortening in colitis mice. Compared with other treatments, cell populations of CD4 + IL-4 + Th2, CD4 + CD25 + FOXP3 + Treg, and CD68 + CD206 + macrophages in spleens were also significantly upregulated in DKK1 low -ERC group ( p < 0.05). In addition, lower expression of pro-inflammatory (TNF-α and IFN-γ), but higher levels of anti-inflammatory cytokines (IL-4 and IL-10) and β-catenin were detected in colons in DKK1 low -ERC group ( p < 0.01 vs. other groups). Conclusions DKK1 low -ERCs display augmented immunoregulatory ability and therapeutic effects in DSS-induced colitis.