Jun-Seop Shin

Long-term control of diabetes in immunosuppressed nonhuman primates (NHP) by the transplantation of adult porcine islets.

Pig islets are an alternative source for islet transplantation to treat type 1 diabetes (T1D), but reproducible curative potential in the pig‐to‐nonhuman primate (NHP) model has not been demonstrated. Here, we report that pig islet grafts survived and maintained normoglycemia for >6 months in four of five consecutive immunosuppressed NHPs. Pig islets were isolated from designated pathogen‐free (DPF) miniature pigs and infused intraportally into streptozotocin‐induced diabetic rhesus monkeys under pretreatment with cobra venom factor (CVF), anti‐thymocyte globulin (ATG) induction and maintenance with anti‐CD154 monoclonal antibody and low‐dose sirolimus. Ex vivo expanded autologous regulatory T cells were adoptively transferred in three recipients. Blood glucose levels were promptly normalized in all five monkeys and normoglycemia (90–110 mg/dL) was maintained for >6 months in four cases, the longest currently up to 603 days. Intravenous glucose tolerance tests during the follow‐up period showed excellent glucose disposal capacity and porcine C‐peptide responses. Adoptive transfer of autologous regulatory T cells was likely to be associated with more stable and durable normoglycemia. Importantly, the recipients showed no serious adverse effects. Taken together, our results confirm the clinical feasibility of pig islet transplantation to treat T1D patients without the need for excessive immunosuppressive therapy.

Streptozotocin-induced diabetes can be reversed by hepatic oval cell activation through hepatic transdifferentiation and pancreatic islet regeneration

Hepatic oval cells have shown the potential to transdifferentiate into insulin-producing cells when cultured with high glucose concentrations. However, it remains unknown whether the oval cells can contribute to insulin production in diabetic mice. In this study, our aim was to investigate the response of activated hepatic oval cells to hyperglycemic conditions. C57BL/6 mice were fed a diet containing 0.1% 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) for 4 weeks to activate the hepatic oval cell population before inducing hyperglycemia with streptozotocin (STZ). Despite the initial hyperglycemia (341±15 mg/dl), the blood glucose levels of DDC-STZ-treated mice were significantly improved within 6 weeks (185±12 mg/dl). During the initial hyperglycemic stage, DDC-STZ-treated livers expressed pancreatic developmental, endocrine and exocrine genes. Hepatic insulin production was confirmed by immunohistochemistry and ELISA. These results suggested that transdifferentiated hepatic oval cell population contributed to the amelioration of hyperglycemia. We additionally determined that DDC-STZ-treated pancreata played a critical role in complete reversal of hyperglycemia as evidenced by extensive β-cell regeneration and increase of pancreatic insulin content after STZ treatment, which is rarely observed in other adult STZ models. Reversal of hyperglycemia in this model seems to be accomplished by biphasic insulin augmentation, first by hepatic transdifferentiation, and followed by endogenous β-cell regeneration in the pancreas. The DDC-STZ treatment provides a novel injury model for better understanding of the functional behavior of hepatic and pancreatic stem/progenitor cell population under hyperglycemic condition, which may yield critical information for developing β-cell-based therapies to treat diabetes.

Immunomodulation of Delayed-Type Hypersensitivity Responses by Mesenchymal Stem Cells Is Associated with Bystander T Cell Apoptosis in the Draining Lymph Node

Disease amelioration by mesenchymal stem cells (MSCs) has been shown to be closely related to their immunomodulatory functions on the host immune system in many disease models. However, the underlying mechanisms of how these cells affect the immune cells in vivo are not fully understood. In this study, we report findings that a small but significant number of MSCs accumulate in the secondary lymphoid organs and attenuate delayed-type hypersensitivity (DTH) response by inducing apoptotic cell death of surrounding immune cells in the draining lymph node (LN). In the migration study, i.v. infused GFP-MSCs preferentially accumulated at the boundary between the paracortical area and the germinal center in the LNs, in close proximity to various types of immune cells including T, B, and dendritic cells in a dose-dependent manner. As a result, accumulated MSCs markedly attenuated DTH response in proportion to the number of MSCs infused. During the DTH response, the infiltration of T cells in the challenged site was significantly decreased, whereas a number of apoptotic T cells were remarkably increased in the draining LN. Apoptosis was significantly induced in activated T cells (CD3+ and BrdU+), but not in the resting T cells (CD3+ and BrdU−). NO was associated with these apoptotic events. Taken together, we conclude that significant numbers of i.v. infused MSCs preferentially localize in the draining LN, where they induce apoptosis of the activated T cells by producing NO and thus attenuate the DTH response.

Bortezomib can suppress activation of rapamycin-resistant memory T cells without affecting regulatory T-cell viability in non-human primates.

Background. Memory T cells specific for donor antigens are currently recognized as a significant barrier for maintaining a successful transplant. Furthermore, it has been shown that commonly used immunosuppressive drugs do not alleviate this memory response. Here, we report that rapamycin allows significant proliferation of memory T cells and bortezomib can abrogate the proliferation of rapamycin-resistant memory T cells when preserving the survival of regulatory T cells. Methods. Peripheral blood mononuclear cells freshly isolated from non-human primates were stimulated with anti-CD3/CD28 antibodies, and inhibitory and apoptotic effects of rapamycin and bortezomib on memory T-cell proliferation were investigated. The CD95 marker in CD3+ T cells was used for the separate enrichment of memory T cells and naïve T cells. Results. Rapamycin at the level even higher than therapeutic concentration could not suppress the proliferation of a significant proportion of memory T cells. However, the combined administration of bortezomib and rapamycin abrogated the proliferation of rapamycin-resistant memory T cells. Furthermore, bortezomib preserved the survival of preexisting CD4+FoxP3+ regulatory T cells, while inducing apoptosis of CD4+FoxP3− conventional T cells. The combined administration of low doses of rapamycin and bortezomib also exerted an additive effect on suppressing T-cell proliferation. Cytokine analysis demonstrated that bortezomib could not only suppress rapamycin-permissive interleukin (IL)-6 production, but also production of interferon (IFN)-γ, IL-4, and IL-10. Conclusions. This article provides in vitro data from which immunosuppressive regimens for the effective control of memory T cells in non-human preclinical experiments and in clinical trials are selected.

In situ induction of dendritic cell–based T cell tolerance in humanized mice and nonhuman primates

Administration of an ICAM-1–specific antibody arrests dendritic cells in a semi-immature state and facilitates antigen-specific T cell tolerance to islet allografts in humanized mice and Rhesus monkeys.

Human β-defensin 2 is induced by interleukin-1β in the corneal epithelial cells

Mammalian epithelia produce the various antimicrobial peptides against the bacterial or viral infection, thereby acting as the active immune modulators in the innate immunity. In this study, we examined the effects of the various proinflammatory cytokines or LPS on cell viability and antimicrobial β-defensin gene expressions in human corneal epithelial cells. Results showed that the cytokines or LPS did not exert severe cytotoxic effects on the cells, and that β-defensin 1 was constitutively expressed, while β-defensin 2 was specifically induced by IL-1β, supporting the idea that these cytokines or LPS involve the defense mechanism in the cornea. Furthermore, the reporter and gel shift assay to define the induction mechanism of β-defensin 2 by IL-1β demonstrated that the most proximal NF-kB site on the promoter region of β-defensin 2 was not critical for the process. Data obtained from the normal or patients with the varying ocular diseases showed that our in vitro results were relevant in the clinical settings. Our results clearly demonstrated that β-defensin 1 and 2 are important antimicrobial peptides in the corneal tissues, and that the mechanistic induction process of β-defensin 2 by IL-1β is not solely dependent on proximal NF-kB site activation, thus suggesting that the long distal portion of the promoter is needed for the full responsiveness toward IL-1β.

Islet isolation from adult designated pathogen‐free pigs: use of the newer bovine nervous tissue–free enzymes and a revised donor selection strategy would improve the islet graft function

Jin S‐M, Shin JS, Kim KS, Gong C‐H, Park SK, Kim J‐S, Yeom S‐C, Hwang ES, Lee CT, Kim S‐J, Park C‐G. Islet isolation from adult designated pathogen‐free pigs: use of the newer bovine nervous tissue–free enzymes and a revised donor selection strategy would improve the islet graft function. Xenotransplantation 2011; 18: 369–379.

Efficient and simple plant regeneration via organogenesis from leaf segment cultures of persimmon (Diospyros kaki Thunb.)

SummaryAn efficient and simple plant regeneration system via organogenesis from leaf segments of persimmon (Diospyros kaki Thunb.) cultivars ‘Fuyu’ and ‘Nishimurawase’ has been developed. The regeneration capacity was influenced by the culture vessels, gelling agents, plant growth regulators, and light conditions. Leaf explants taken from in vitro shoots were cultured on a modified Murashige and Skoog medium (MS1/2N), for 16 wk without transfer to fresh medium. Adventious shoots appeared after 4 and 8 wk in culture of ‘Nishimurawase’ and ‘Fuyu’ tissues, respectively. The culture of leaf explants in Erlenmeyer flasks with medium containing 4 g l−1 agar enhanced shoot formation in comparison to media with increased agar concentrations. Optimal shoot regeneration was obtained with 5 mg l−1 (22.8 μM) zeatin and 0.1 mg l−1 (0.05 μM) indole-3-butyric acid (IBA) for ‘Nishimurawase’, and 10 mg l−1 (45.6 μM) zeatin and 0.1 mg l−1 (0.05 μM) IBA for ‘Fuyn’. Shoot regeneration frequencies in both cultivars were 100%, and shoot numbers per explant reached up to 9.2 for ‘Nishimurawase’ and 2.2 for ‘Fuyu’. Dark incubation during the first 4–5 wk was the most effective condition to successfully influence shoot regeneration in both cultivars. While dark incubation was essential for adventitious shoot formation by ‘Fuyu’, it was only slightly beneficial to ‘Nishimurawase’. More than 80% of the regenerated shoots rooted within 4 wk on hormone-free MS1/2N demium after having been dipped for 30 s in 250 mg l−1 (1.1. mM) IBA solution.

The role of the alternative complement pathway in early graft loss after intraportal porcine islet xenotransplantation.

Background Intraportal islet transplantation (ITx) causes instant blood-mediated inflammatory reaction (IBMIR), resulting in an early loss of transplanted islets. Porcine islets, transplanted intraportally into nonhuman primates (NHPs), induce complement activation, contributing to the development of IBMIR; however, the exact mechanism is not clear. Methods Complement activation were compared after incubation of purified adult porcine islets in 20% human serum with or without complement inhibitors, C1 esterase inhibitor (C1E-inh), anti-factor B, and purified human factor H. Intraportal porcine ITx was performed in diabetic NHPs to which cobra venom factor (CVF), factor H, or none of complement inhibitor was administered during the peritransplant period. The extent of complement activation and function of islet grafts were monitored after ITx. Results The incubation of porcine islets with human serum resulted in generation of C3a, C4d, and factor Bb in the fluid phase. However, the generation of C3a after incubation was suppressed by anti-factor B or factor H, but not by C1E-inh. Moreover, in NHPs with porcine ITx, the administration of CVF or factor H ameliorated the increase in plasma C3a and factor Bb levels, as well as early release of porcine C-peptide after ITx. Furthermore, the functional survival of islet grafts was prolonged in the recipients of the CVF group compared to those in the control group. Conclusions The alternative complement pathway contributes to the development of IBMIR and the early loss of grafts in NHPs with porcine ITx. Complement inhibition during the peritransplant period may be beneficial for the survival of islet grafts.

Murine mesenchymal stem cells suppress T lymphocyte activation through IL-2 receptor α (CD25) cleavage by producing matrix metalloproteinases.

Mesenchymal stem cells (MSCs) are multipotent, non-hematopoietic stem cells that exhibit the capacity to inhibit the proliferation of a variety of immune cells. However, the underlying mechanisms of the immunosuppressive effects of MSCs are still obscure. Therefore, we attempted to identify the mechanisms underlying immunosuppression toward the activated T lymphocytes by MSCs in a murine model. In particular, we aimed to find possible factors derived from MSCs that drive this phenomenon. We found that T lymphocytes incubated with conditioned media of MSCs (MSC CM) entered into apoptosis and were subjected to cell cycle arrest during the course of activation, and these phenomena were accompanied by the reduction of IL-2 production. Specifically, matrix metalloproteinases (MMPs) derived from MSCs caused cleavage of IL-2 receptor α (CD25) from the surface of activated T cells, and as a consequence, IL-2 signaling in response to engagement of the IL-2 receptor (IL-2R) was downregulated. The inhibition of MMP activity in the MSC CM by GM6001 abrogated CD25 cleavage and restored IL-2 production from the activated splenocytes. However, the blockade of MMP activity could not fully restore the proliferative response and apoptosis of T cells altered by MSC CM. In conclusion, MSC-derived MMPs have a significant role in the suppression of IL-2 production through induction of CD25 cleavage and have a partial role in the suppression of T cell proliferation.