The IL-1 Receptor Antagonist Anakinra Enhances Survival and Function of Human Islets during Culture: Implications in Clinical Islet Transplantation

Abstract

Beta-cell replacement by human islet transplantation is a promising approach for treatment of type 1 diabetes (T1D). However, it is currently limited by low number of available pancreatic donors and loss of islets during isolation, pre-transplant culture, and following transplantation. Cytokines such as IL-1β have been implicated in beta-cell apoptosis in both T1D and T2D. Anakinra (Kineret) is an interleukin-1 (IL-1) receptor antagonist that competitively inhibits the binding of IL-1 proteins to their membrane receptor and thus blocks the biologic activity of naturally produced IL-1α and IL-1β. Anakinra is currently in clinical use for treatment of IL-1β-mediated inflammation in rheumatoid arthritis. Interestingly, recent studies have shown that Anakinra improves glycemic control in animal models of T2D. In this study, we tested whether treatment with Anakinra could enhance survival and function of isolated human islets during pre-transplant culture as a potential approach to improve quality and/or quantity of isolated islets for transplantation. Freshly isolated islets from five cadaveric human donors were cultured in CMRL (5 mM glucose, 37°C, 10% fetal bovine serum) without or with Anakinra (10 μg/ml) for 2 or 4 days. Beta-cell apoptosis, mass, function, and islet beta/alpha cell ratio were assessed in human islets before and following culture. As expected, culture of human islets resulted in an increase in the proportion of apoptotic (TUNEL-positive) islet beta cells in a time-dependent manner as assessed by immunostaining for insulin and TUNEL (d0: 2.2 ± 1.3%; d2: 4.3 ± 1.5; d4: 6.1 ± 2.0, P< 0.05). Treatment with Anakinra markedly reduced beta-cell apoptosis in cultured human islets (+An (d2): 2.4 ± 1.2; +An (d4): 3.1 ± 1.6, P< 0.05). Reduced beta-cell apoptosis was associated with a decrease in caspase-3 activation in beta cells in Anakinra-treated islets compared to non-treated cultured islets. This decrease in beta-cell apoptosis in Anakinra-treated human islets resulted in an increase in the islet beta/alpha cell ratio (-An (d4): 1.8 ± 0.2 vs +An (d4): 2.1 ± 0.2; P< 0.05) and beta-cell mass (beta-cell mass (% d0): -An (d4): 57 ± 3.4% vs +An (d4): 69 ± 3.8%, P< 0.05). Furthermore, Anakinra-treated islets had markedly enhanced beta-cell function compared to non-treated cultured islets manifested as increased insulin response to elevated glucose (-An (d2): 2.4 ± 0.2 vs +An (d2): 3.5 ± 0.4 fold; -An (d4): 2.1 ± 0.2 vs +An (d4): 3.3 ± 0.2 fold, P< 0.05) and increased islet insulin content. In summary, these studies suggest that blocking IL-1β receptor in isolated human islets reduces beta-cell death, preserves beta-cell mass, and enhances beta-cell function during pre-transplant islet culture. Treatment with IL-1 receptor antagonists may therefore provide a new approach to enhance islet beta-cell survival and function during pre-transplant culture thereby increase the success rate of clinical islet transplantation.