Background
R-spondins, including R-spondin 1 (RSPO1), are a family of Wnt ligands that help to activate the canonical Wnt/β-catenin pathway, which is critical for intestinal epithelial cell proliferation and maintenance of intestinal stem cells. This proliferation underpins the epithelial expansion, or intestinal adaptation (IA), that occurs following massive bowel resection and short bowel syndrome (SBS). The
Conclusions
Intraperitoneal injection of rhRSPO1 decreased weight loss in SBS zebrafish with increased β-catenin + cells and cyclin D1 expression at 14 days, indicating improved weight maintenance might result from increased activation of the canonical Wnt pathway.
Methods
Adult male zebrafish were assigned to four groups: sham + PBS, SBS + PBS, sham + rhRSPO1, and SBS + rhRSPO1. Sham fish had a laparotomy alone. SBS fish had a laparotomy with distal intestinal ligation and creation of a proximal stoma. Fish were weighed at initial surgery and then weekly. rhRSPO1 was administered post-operatively following either a one- or two-week dosing schedule with either 3 or 5 intraperitoneal injections, respectively. Fish were harvested at 7 or 14 days with intestinal segments collected for analysis.
Results
Repeated intraperitoneal injection of rhRSPO1 was feasible and well tolerated. At 7 days, intestinal epithelial proliferation was increased by rhRSPO1. At 14 days, SBS + rhRSPO1 fish lost significantly less weight than SBS + PBS fish. Measurements of intestinal surface area were not increased by rhRSPO1 administration but immunofluorescent staining for β-catenin and gene expression for cyclin D1 was increased. Conclusions: Intraperitoneal injection of rhRSPO1 decreased weight loss in SBS zebrafish with increased β-catenin + cells and cyclin D1 expression at 14 days, indicating improved weight maintenance might result from increased activation of the canonical Wnt pathway.