G-CSF and Exenatide Might Be Associated with Increased Long-Term Survival of Allogeneic Pancreatic Islet Grafts

Prolonged Islet Allograft Function is Associated With Female Sex in Patients After Islet Transplantation

BACKGROUND

Islet transplantation (ITx) has proved to be effective in preventing severe hypoglycemia and improving metabolic control in selected subjects with type 1 diabetes. Long-term graft function remains a challenge. Estrogens have been shown to protect β cells from metabolic stresses and improve revascularization of transplanted human islets in the mouse. We aimed to evaluate the influence of sex in allograft survival of ITx recipients.

METHODS

We analyzed a retrospective cohort of ITx recipients (n = 56) followed-up for up to 20 years. Allograft failure was defined as a stimulated C-peptide <0.3 ng/mL during a mixed-meal tolerance test. Subjects were divided into recipients of at least 1 female donor (group 1) and recipients of male donors only (group 2).

RESULTS

Group 1 subjects (n = 25) were aged 41.5 ± 8.4 years and group 2 subjects (n = 22) 45.9 ± 7.3 years (P = 0.062). Female recipient frequency was 44.8% (n = 13) in group 1 and 55.2% (n = 16) in group 2 (P = 0.145). Group 2 developed graft failure earlier than group 1 (680 [286-1624] vs 1906 [756-3256] days, P = 0.038). We performed additional analyses on female recipients only from each group (group 1, n = 16; group 2, n = 20). Female recipients in group 1 exhibited prolonged allograft function compared with group 2, after adjustment for confounders (odds ratio, 28.6; 95% CI, 1.3-619.1; P < 0.05).

CONCLUSION

Recipients of islets from at least 1 female donor exhibited prolonged graft survival compared with recipients of islets from exclusively male donors. In addition, female recipients exhibited prolonged survival compared with male recipients following ITx of at least 1 female donor.

Mechanisms of Immunomodulation and Cytoprotection Conferred to Pancreatic Islet by Human Amniotic Epithelial Cells

Inhibiting pro-inflammatory cytokine activity can reverse inflammation mediated dysfunction of islet grafts. Human amniotic epithelial cells (hAECs) possess regenerative, immunomodulatory and anti-inflammatory properties. We hypothesized that hAECs could protect islets from cellular damage induced by pro-inflammatory cytokines. To verify our hypothesis, hAEC monocultures, rat islets (RI), or RI-hAEC co-cultures where exposed to a pro-inflammatory cytokine cocktail (Interferon γ: IFN-γ, Tumor necrosis factor α: TNF-α and Interleukin-1β: IL-1β). The secretion of anti-inflammatory cytokines and gene expression changes in hAECs and viability and function of RI were evaluated. The expression of non-classical Major Histocompatibility Complex (MHC) class I molecules by hAECs cultured with various IFN-γ concentrations were assessed. Exposure to the pro-inflammatory cocktail significantly increased the secretion of the anti-inflammatory cytokines IL6, IL10 and G-CSF by hAECs, which was confirmed by upregulation of IL6, and IL10 gene expression. HLA-G, HLA-E and PDL-1 gene expression was also increased. This correlated with an upregulation of STAT1, STAT3 and NF-κB1gene expression levels. RI co-cultured with hAECs maintained normal function after cytokine exposure compared to RI cultured alone, and showed significantly lower apoptosis rate. Our results show that exposure to pro-inflammatory cytokines stimulates secretion of anti-inflammatory and immunomodulatory factors by hAECs through the JAK1/2 – STAT1/3 and the NF-κB1 pathways, which in turn protects islets against inflammation-induced damages. Integrating hAECs in islet transplants appears as a valuable strategy to achieve to inhibit inflammation mediated islet damage, prolong islet survival, improve their engraftment and achieve local immune protection allowing reducing systemic immunosuppressive regimens.

Granulocyte Colony-Stimulating Factor Attenuates Renal Ischemia-Reperfusion Injury by Inducing Myeloid-Derived Suppressor Cells

BACKGROUND

Granulocyte colony-stimulating factor (G-CSF) can increase populations of myeloid-derived suppressor cells, innate immune suppressors that play an immunoregulatory role in antitumor immunity. However, the roles of myeloid-derived suppressor cells and G-CSF in renal ischemia-reperfusion injury remain unclear.

METHODS

We used mouse models of ischemia-reperfusion injury to investigate whether G-CSF can attenuate renal injury by increasing infiltration of myeloid-derived suppressor cells into kidney tissue.

RESULTS

G-CSF treatment before ischemia-reperfusion injury subsequently attenuated acute renal dysfunction, tissue injury, and tubular apoptosis. Additionally, G-CSF treatment suppressed renal infiltration of macrophages and T cells as well as renal levels of IL-6, MCP-1, IL-12, TNF-α, and IFN-γ, but it increased levels of IL-10, arginase-1, and reactive oxygen species. Moreover, administering G-CSF after ischemia-reperfusion injury improved the recovery of renal function and attenuated renal fibrosis on day 28. G-CSF treatment increased renal infiltration of myeloid-derived suppressor cells (F4/80^-CD11b⁺Gr-1^int), especially the granulocytic myeloid-derived suppressor cell population (CD11b⁺Ly6Gi^ntLy6C^low); splenic F4/80^-CD11b⁺Gr-1⁺ cells sorted from G-CSF-treated mice displayed higher levels of arginase-1, IL-10, and reactive oxygen species relative to those from control mice. Furthermore, these splenic cells effectively suppressed in vitro T cell activation mainly through arginase-1 and reactive oxygen species, and their adoptive transfer attenuated renal injury. Combined treatment with anti-Gr-1 and G-CSF showed better renoprotective effects than G-CSF alone, whereas preferential depletion of myeloid-derived suppressor cells by pep-G3 or gemcitabine abrogated the beneficial effects of G-CSF against renal injury.

CONCLUSIONS

G-CSF induced renal myeloid-derived suppressor cells, thereby attenuating acute renal injury and chronic renal fibrosis after ischemia-reperfusion injury. These results suggest therapeutic potential of myeloid-derived suppressor cells and G-CSF in renal ischemia-reperfusion injury.

New Frontiers in the Treatment of Type 1 Diabetes

Type 1 diabetes is an autoimmune disease caused by the immune-mediated destruction of pancreatic β cells that results in lifelong absolute insulin deficiency. For nearly a century, insulin replacement has been the only therapy for most people living with this disease. Recent advances in technology and our understanding of β cell development, glucose metabolism, and the underlying immune pathogenesis of the disease have led to innovative therapeutic and preventative approaches. A paradigm shift in immunotherapy development toward the targeting of islet-specific immune pathways involved in tolerance has driven the development of therapies that may allow for the prevention or reversal of this disease while avoiding toxicities associated with historical approaches that were broadly immunosuppressive. In this review, we discuss successes, failures, and emerging pharmacological therapies for type 1 diabetes that are changing how we approach this disease, from improving glycemic control to developing the "holy grail" of disease prevention.

The greater omentum as a site for pancreatic islet transplantation

The greater omentum is a highly vascularized anatomical structure in the peritoneal cavity. Its main components are connective, adipose and vascular cells, along with specialized immune cells. The omentum functions as a site for fat accumulation, it has adhesive properties to control traumatized and inflamed tissues, and a function in local hemostasis, immune responses, and revascularization. Other functions include the absorption of fluids, the phagocytosis of particulate matter, and foreign body reaction. The omentum is catalyzing significant interest for its potential as a site for pancreatic islet and cell transplantation. Our knowledge about this structure, its functions, and its potential as a site for transplantation is poised to grow in the coming years.

Co-microencapsulation of BMSCs and mouse pancreatic β cells for improving the efficacy of type I diabetes therapy

INTRODUCTION

To overcome the shortcomings of pancreas transplantation and insulin injection treatment for type I diabetes, biocompatible materials were used to prepare alginate-chitosan-alginate microcapsules that co-encapsulated bone marrow mesenchymal stem cells and mouse pancreatic β cells to treat diabetic mice.

METHODS

Blank alginate-chitosan-alginate (ACA) microcapsules and co-microencapsulated cells were prepared using a high-voltage electrostatic method and then characterized using an inverted microscope. Cell viability was evaluated using AO/EB staining. ELISA kit was used to detect insulin secretion. Peri-orbital blood samples were obtained from the mice for blood glucose determination every week for one month.

RESULTS

After 28 days of in vitro culture, the secretion of insulin following co-microencapsulation was higher than that observed for microencapsulated beta-TC-6 cells alone. On the 28th day after transplantation, the blood glucose level was 6.86 mmol/L in the microencapsulated beta-TC-6 group. On the 14th day, the blood glucose level was 6.80 mmol/L in the co-microencapsulated BMSC/beta-TC-6 group, which was close to the normal blood glucose level of healthy mice. These results indicated that the efficacy in reducing blood glucose was better in the co-microencapsulated BMSC/beta-TC-6 group.

CONCLUSIONS

This primary study indicated that combining microencapsulation technology and co-culture of stem cells and somatic cells shows promise for the treatment of type I diabetes mellitus.