MMP9 and colitis: Similar to UC in human disease, in animal models of dextran sodium sulphate [DSS]-induced colitis, MMP9 expression is greatly increased in neutrophilic infiltrates and co-localises to regions of epithelial and endothelial basement membrane destruction.26,32,33 Several studies have demonstrated that genetic ablation or pharmacological inhibition of MMP9 attenuates disease severity and tissue damage in the DSS UC model.32–36 As such, the fact that specific inhibition of MMP9 with andecaliximab was ineffective in reducing UC disease severity in this study was surprising.