HPSE and type 1 diabetes mellitus: In view of the established role for Hpse in leukocyte migration in other experimental models of inflammation (see above), we predicted that during T1D development, Hpse produced by islet beta cell-specific autoreactive T cells, inflammatory leukocytes, and possibly endothelial cells in the pancreatic vasculature, would be required to degrade HS in the sub-vascular endothelial BM.