Abstract
Purpose :
Patients with diabetes mellitus (DM) are at an increased risk for developing corneal complications, including delayed wound healing. ISG15 is an interferon-induced, ubiquitin-like protein that is either conjugated to intracellular target proteins or secreted as chemokines. We sought to characterize its expression and function in corneal wound healing in normal and diabetic mice.
Methods :
C57BL/6 wildtype and ISG15 KO mice were induced to develop diabetes by streptozotocin (STZ), and wound-healing assays were performed 10 weeks afterward. ISG15 expression and/or distribution were assessed by real-time PCR and immunohistochemistry. The role of ISG15 in mediating epithelial wound closure was determined by create a 2 mm epithelial debridement wound in wild type and ISG15 KO B6 mouse corneas. Expression of p-AKT was assessed using Western blotting. Infiltrated PMN and macrophages were assessed by immunohistochemistry with NIMP-R14 and F4/80 antibodies. The influence of ISG15 deficiency on the expression of USP18, UBE2L6, IL1Ra, IL1β, TGFβ1 and 3 were determined by real-time PCR at 24 hpw.
Results :
ISG15 expression was upregulated in response to wounding; this wound-induced upregulations was significantly suppressed by hyperglycemia. Deficiency of ISG15 had no effects on diabetes induction with STZ and significantly delayed epithelial wound closure only in normoglycemia mice. The levels of phospho-AKT, indicative of PI3K-AKp activation, were much lower in healing corneas of ISG15-/-, compared to WT mice. Deficiency of ISG15 also resulted in a marked decrease in the infiltration in neutrophils and macrophages, particularly near the leading edge. Knockdown ISG15 induce upregulation of IL1Ra and IL1β while downregulation of USP18, UBE2L6, TGFβ1 and β3.
Conclusions :
ISG15 plays a role in mediating epithelial wound healing and its impaired expression may contribute to delayed wound healing in diabetic mouse corneas.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.