Shaheed Merani

Inhibition of Th17 cells regulates autoimmune diabetes in NOD mice

OBJECTIVE The T helper 17 (Th17) population, a subset of CD4-positive T-cells that secrete interleukin (IL)-17, has been implicated in autoimmune diseases, including multiple sclerosis and lupus. Therapeutic agents that target the Th17 effector molecule IL-17 or directly inhibit the Th17 population (IL-25) have shown promise in animal models of autoimmunity. The role of Th17 cells in type 1 diabetes has been less clear. The effect of neutralizing anti–IL-17 and recombinant IL-25 on the development of diabetes in NOD mice, a model of spontaneous autoimmune diabetes, was investigated in this study. RESEARCH DESIGN AND METHODS AND RESULTS Although treatment with either anti–IL-17 or IL-25 had no effect on diabetes development in young (<5 weeks) NOD mice, either intervention prevented diabetes when treatment was started at 10 weeks of age (P < 0.001). Insulitis scoring and immunofluorescence staining revealed that both anti–IL-17 and IL-25 significantly reduced peri-islet T-cell infiltrates. Both treatments also decreased GAD65 autoantibody levels. Analysis of pancreatic lymph nodes revealed that both treatments increased the frequency of regulatory T-cells. Further investigation demonstrated that IL-25 therapy was superior to anti–IL-17 during mature diabetes because it promoted a period of remission from new-onset diabetes in 90% of treated animals. Similarly, IL-25 delayed recurrent autoimmunity after syngeneic islet transplantation, whereas anti–IL-17 was of no benefit. GAD65-specific ELISpot and CD4-positive adoptive transfer studies showed that IL-25 treatment resulted in a T-cell–mediated dominant protective effect against autoimmunity. CONCLUSIONS These studies suggest that Th17 cells are involved in the pathogenesis of autoimmune diabetes. Further development of Th17-targeted therapeutic agents may be of benefit in this disease.

Sirolimus‐based immunosuppression is associated with increased survival after liver transplantation for hepatocellular carcinoma

Liver transplantation is an important treatment option for selected patients with nonresectable hepatocellular carcinoma (HCC). Several reports have suggested a lower risk of posttransplant tumor recurrence with the use of sirolimus and a higher one with calcineurin inhibitors, but the selection of an ideal immunosuppression protocol is still a matter of debate. The aim of this study was to define the immunosuppression associated with the best survival after liver transplantation for HCC. It was based on the Scientific Registry of Transplant Recipients and included 2,491 adult recipients of isolated liver transplantation for HCC and 12,167 for non‐HCC diagnoses between March 2002 and March 2009. All patients remained on stable maintenance immunosuppression protocols for at least 6 months posttransplant. In a multivariate analysis, only anti‐CD25 antibody induction and sirolimus‐based maintenance therapy were associated with improved survivals after transplantation for HCC (hazard ratio [HR] 0.64, 95% confidence interval [CI]: 0.45–0.9, P ≤ 0.01; HR 0.53, 95% CI: 0.31–0.92, P ≤ 0.05, respectively). The other studied drugs, including calcineurin inhibitors, did not demonstrate a significant impact. In an effort to understand whether the observed effects were due to a direct impact of the drug on tumor or more on liver transplant in general, we conducted a similar analysis on non‐HCC patients. Although anti‐CD25 induction was again associated with a trend toward improved survival, sirolimus showed a trend toward lower rates of survival in non‐HCC recipients, confirming the specificity of its beneficial impact to cancer patients. Conclusion: According to these data, sirolimus‐based immunosuppression has unique posttransplant effects on HCC patients that lead to improved survival. (HEPATOLOGY 2010.)

Optimal implantation site for pancreatic islet transplantation

Since the first report of successful pancreatic islet transplantation to reverse hyperglycaemia in diabetic rodents, there has been great interest in determining the optimal site for implantation. Although the portal vein remains the most frequently used site clinically, it is not ideal. About half of the islets introduced into the liver die during or shortly after transplantation. Although many patients achieve insulin independence after portal vein infusion of islets, in the long term most resume insulin injections.

Inhibition of Allergic Inflammation in the Airways Using Aerosolized Antisense to Syk Kinase

Activation of the protein tyrosine kinase Syk is an early event that follows cross-linking of FcγR and FcεR, leading to the release of biologically active molecules in inflammation. We reported previously that aerosolized Syk antisense oligodeoxynucleotides (ASO) depresses Syk expression in inflammatory cells, the release of mediators from alveolar macrophages, and pulmonary inflammation. To study the effect of Syk ASO in allergic inflammation and airway hyperresponsiveness, we used the Brown Norway rat model of OVA-induced allergic asthma. Syk ASO, delivered in a liposome, carrier/lipid complex by aerosol to rats, significantly inhibited the Ag-induced inflammatory cell infiltrate in the bronchoalveolar space, decreasing both neutrophilia and eosinophilia. The number of eosinophils in the lung parenchyma was also diminished. Syk ASO also depressed up-regulation of the expression of β2 integrins, α4 integrin, and ICAM-1 in bronchoalveolar lavage leukocytes and reversed the Ag-induced decrease in CD62L expression on neutrophils. Furthermore, the increase in TNF levels in bronchoalveolar lavage following Ag challenge was significantly inhibited. Syk ASO also suppressed Ag-mediated contraction of the trachea in a complementary model. Thus, aerosolized Syk ASO suppresses many of the central components of allergic asthma and inflammation and may provide a new therapeutic approach.

Current status of pancreatic islet transplantation

DM (diabetes mellitus) is a metabolic disorder of either absolute or relative insulin deficiency. Optimized insulin injections remain the mainstay life-sustaining therapy for patients with T1DM (Type I DM) in 2006; however, a small subset of patients with T1DM (approx. 10%) are exquisitely sensitive to insulin and lack counter-regulatory measures, putting them at higher risk of neuroglycopenia. One alternative strategy to injected insulin therapy is pancreatic islet transplantation. Islet transplantation came of age when Paul E. Lacy successfully reversed chemical diabetes in rodent models in 1972. In a landmark study published in 2000, Shapiro et al. [A. M. Shapiro, J. R. Lakey, E. A. Ryan, G. S. Korbutt, E. Toth, G. L. Warnock, N. M. Kneteman and R. V. Rajotte (2000) N. Engl. J. Med. 343, 230-238] reported seven consecutive patients treated with islet transplants under the Edmonton protocol, all of whom maintained insulin independence out to 1 year. Substantial progress has occurred in aspects of pancreas procurement, transportation (using the oxygenated two-layer method) and in islet isolation (with controlled enzymatic perfusion and subsequent digestion in the Ricordi chamber). Clinical protocols to optimize islet survival and function post-transplantation improved dramatically with the introduction of the Edmonton protocol, but it is clear that this approach still has potential limitations. Newer pharmacotherapies and interventions designed to promote islet survival, prevent apoptosis, to promote islet growth and to protect islets in the long run from immunological injury are rapidly approaching clinical trials, and it seems likely that clinical outcomes of islet transplantation will continue to improve at the current exponential pace.

The impact of waiting list alpha-fetoprotein changes on the outcome of liver transplant for hepatocellular carcinoma

BACKGROUND & AIMS Liver transplantation is a recognized treatment for selected patients with hepatocellular carcinoma (HCC), but transplant criteria still need to be refined, especially in the case of more advanced or downstaged tumors. METHODS The present study investigated alpha-fetoprotein (AFP) as a predictor of outcome in 6817 patients listed with a diagnosis of HCC in the Scientific Registry of Transplant Recipients. RESULTS Local pre-transplant HCC treatment was used in 41% of patients on the waiting list. Patients with AFP levels>400 ng/ml at the time of listing who were downstaged to AFP ≤400 ng/ml had better intent-to-treat survival than patients failing to reduce AFP to ≤400 (81% vs. 48% at 3 years, p ≤0.001) and comparable survival to patients with stable AFP ≤400 ng/ml (74%, p = 0.14). Patients with AFP levels decreased ≤400 ng/ml and patients with levels persistently ≤400 ng/ml also had similar drop-out rates from the list (10% in both groups) and post-transplant survival rates (89% vs. 78% at 3 years, p = 0.11). Such an AFP downstaging was associated with good survivals whatever the level of the original AFP (even if originally>1000 ng/ml). Only the last pre-transplant AFP independently predicted survival (p ≤0.001), unlike AFP at listing or AFP changes. CONCLUSIONS Overall, downstaging HCC patients with high AFP is feasible and leads to similar intent-to-treat and post-transplant survivals to those of patients with AFP persistently low. Only last AFP appears relevant for patient selection before transplantation and should be used in combination with morphological variables.

Liraglutide, a long-acting human glucagon-like peptide 1 analogue, improves human islet survival in culture

The culture of human islets is associated with approximately 10–20% islet loss, occasionally preventing transplantation. Preconditioning of the islets to improve postculture yields would be of immediate benefit, with the potential to increase both the number of transplanted patients and their metabolic reserve. In this study, the effect of liraglutide, a long‐acting human glucagon‐like peptide 1 analogue, on cultured human islets was examined. Culture with liraglutide (1 μmol/l) was associated with a preservation of islet mass (significantly more islets at 24 and 48 h, compared to control; P ≤ 0.05 at 24 and 48 h) and with the presence of larger islets (P ≤ 0.05 at 48 h). These observations were supported by reduced apoptosis rates  after 24 h of treatment. We also demonstrated that human islet engraftment is improved in C57Bl/6‐RAG−/− mice treated with liraglutide 200 μg/kg sc twice daily (P ≤ 0.05), suggesting that liraglutide should be continued after transplantation. Overall, these data demonstrate the beneficial effect of liraglutide on cultured human islets, preserving islet mass. They support the design of clinical studies looking at the effect of liraglutide in clinical islet transplantation.

The role of macrophage migration inhibitory factor on glucose metabolism and diabetes

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine involved in many inflammatory reactions and disorders, and it has become evident that it also affects glucose homeostasis. The protein is produced by pancreatic beta cells and can promote the release of insulin. It also modulates glucose uptake, glycolysis and insulin resistance in insulin target cells such as the adipocyte, myocyte and cardiomyocyte. Possessing both immunological and endocrinological properties, MIF has been associated with the development of type 1 and type 2 diabetes, and it may be important in the setting of islet transplantation. The present review summarises our current knowledge, based on clinical and research data, on the impact of MIF on both physiological and pathological aspects of glucose metabolism.

The caspase selective inhibitor EP1013 augments human islet graft function and longevity in marginal mass islet transplantation in mice.

OBJECTIVE—Clinical islet transplantation can provide insulin independence in patients with type 1 diabetes, but chronic graft failure has been observed. This has been attributed in part to loss of ≥60% of the transplanted islets in the peritransplant period, resulting in a marginal implant mass. Strategies designed to maximize survival of the initial islet mass are likely to have major impact in enhancing long-term clinical outcomes. EP1013 (N-benzyloxycabonyl-Val Asp-fluoromethyl ketone [zVD-FMK]), is a broad-spectrum caspase selective inhibitor with no observed toxicity in rodents. RESEARCH DESIGN AND METHODS—The therapeutic benefit of EP1013 was examined in a syngeneic rodent islet transplant model using deceased donor human islets to determine whether the amount of tissue required to restore euglycemia in diabetic animals could be reduced. RESULTS—EP1013 (combined pretransplant islet culture for 2 h and in vivo treatment for days 0–5 posttransplant) significantly improved marginal islet mass function following syngeneic islet transplantation in mice, even at lower doses, compared with previous studies using the pan-caspase inhibitor N-benzyloxycabonyl-Val Ala-Asp-fluoromethyl ketone (zVAD-FMK). EP1013 supplementation in vitro improved human islet yields following prolonged culture and reversed diabetes following implantation of a marginal human islet mass (80–90% reduction) into mice. CONCLUSIONS—Our data suggest that EP1013 therapy will markedly reduce the islet mass required in clinical islet transplantation, improving insulin independence rates following single-donor infusion.

Liraglutide, a long-acting human glucagon-like peptide 1 analog, improves glucose homeostasis in marginal mass islet transplantation in mice

The current scarcity of high-quality deceased pancreas donors prevents widespread application of islet transplantation for treatment of labile type 1 diabetes mellitus. Opportunities for the improvement of current techniques include optimization of islet isolation and purification, use of culture with pharmacological insulinotropic agents, strategies to reduce graft rejection and inflammation, and the search for alternative insulin producing tissue. Here, we report our findings on the efficacy of the long-acting human glucagon-like peptide 1 analog, liraglutide, in a mouse model of marginal mass islet transplantation. Liraglutide was administered (200 microg/kg sc twice daily) after a marginal mass syngeneic islet transplant in streptozotocin-induced diabetic BALB/c mice. Time-to-normoglycemia was significantly shorter in liraglutide-treated animals (median 1 vs. 7 d; P = 0.0003), even in recipients receiving sirolimus (median 1 vs. 72.5 d; P < 0.0001). Liraglutide-treated animals also demonstrated improved glucose tolerance as assessed by an ip glucose tolerance test. Liraglutide discontinuation at postoperative d 90 resulted in diminished glucose tolerance during the ip glucose tolerance test, whereas a late-start liraglutide therapy 90 d after transplant resulted in no improvement. These findings suggest that liraglutide therapy mediates early and late insulinotropic effects. In accord with this hypothesis, insulin/terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick end labeling fluorescence microscopy showed reduced transplanted beta-cell apoptosis in liraglutide-treated recipients 48 h after transplant. In addition, liraglutide resulted in improved glucose-dependent insulin secretion. Overall, our data show that liraglutide has a beneficial impact on the engraftment and function of syngeneic islet transplants in mice, when administered continuously starting on the day of transplant.