Improving Clinical Islet Transplantation Outcomes.

Abstract

Transplantation of islets purified from donor pancreata is one of only a few clinical strategies that can reverse type 1 diabetes (T1D) and restore glycemic control (1–3). Significant progress has been made by improving transplantation strategies in areas including immune suppressive regimes, islet quality, transplanted β-cell mass and purity, and donor selection (4–6). However, while improved metabolic control and reduced glycemic side effects such as hypoglycemia persist long term in the majority of T1D patients, insulin independence beyond 1 year is only achieved in a minority of cases (2). Early loss of islet mass upon portal vein infusion is believed to have a major negative impact (7). Recurrence of insulitis, the hallmark of T1D immunopathogenesis leading to autoimmune mediated β-cell destruction, and islet allograft rejection pose additional therapeutic hurdles (8,9). Recently, neutrophils were suggested as part of the innate immune system contributing to development of T1D (10). Chemokines produced by distressed islet tissue attract leukocytes to the site of implantation (Fig. 1). The chemokine CXCL8, produced by recruited and resident macrophages, attracts neutrophils carrying its receptors CXCR1/2 to the lesion. In this issue of Diabetes Care , Piemonti and colleagues (11) now report the results of a phase 3 clinical trial assessing whether interference in homing of leukocytes to the implanted islet graft using reparixin, a small molecule that interferes with CXCR1/2 signaling, may improve transplantation outcome. The rationale for this strategy is outstanding. Early studies in mice and humans were very encouraging. Treatment with reparixin prevented and reversed autoimmune diabetes in NOD mice and improved graft survival …