[Efficacy and safety of transbronchial cryobiopsy in the etiologic diagnosis of diffuse lung disease]

Objective: To assess the efficacy and safety of transbronchial cryobiopsy (TBCB) for the etiologic evaluation of diffuse lung disease (DLD). Methods: Between December 2015 to April 2017, a total of 38 patients with DLD met the inclusion criteria for TBCB in the First Affiliated Hospital of Chongqing Medical University, and 35 of them consented to undergo the procedure under rigid or flexible bronchoscopy. On the tissues obtained from the 35 patients, histopathologic and microbiological evaluations were performed, and together with clinical and radiological manifestations, diagnoses were made and the efficacy of TBCB in the diagnosis of DLD was confirmed, and then therapies were planned accordingly. Complications of the biopsy procedures were recorded. Results: Of the 35 patients who were enrolled, 24 underwent TBCB under rigid bronchoscopy and 11 under flexible bronchoscopy. Another 3 patients refused the procedure due to disinclination to invasive examinations. One single procedure of TBCB took (51.8±19.2) min on average, the median number of tissues obtained was 6 (5, 8), and the median area of tissues was 15 (9, 20) mm(2).Definite diagnoses were reached in 33 patients, including idiopathic nonspecific interstitial pneumonia (n=8), connective tissue disease-interstitial lung disease (n=8), occupational lung disease (n=4), idiopathic pulmonary fibrosis (n=3), interstitial pneumonia with autoimmune features (n=3), tuberculosis (n=2), cryptogenic organization pneumonia (n=1), acute interstitial pneumonia (n=1), pulmonary infection (n=1), hypersensitivity pneumonia (n=1) and sarcoidosis (n=1). Diagnostic yield was 94.3% (33 out of 35 cases diagnosed). Pneumothorax occurred in 3 patients (1 patients with mild pneumothorax , 1 moderate and 1 severe), and were resolved with thoracic puncture or pleural drainage. Bleeding occurred in all 24 patients who received TBCB under rigid bronchoscopy (11 patients with mild bleeding, 12 moderate and 1 severe) and was controlled after coagulation measures. After one month of treatment according to the diagnoses acquired with cryobiopsy, the condition was cured in 1 patient (3.0%), alleviated in 17 (51.5%), stable in 11 (33.3%), and deteriorated in 4 (12.1%). Conclusion: TBCB yields reliable diagnoses with a good safety profile.

Inversion of Qubit Energy Levels in Qubit-Oscillator Circuits in the Deep-Strong-Coupling Regime

We report on experimentally measured light shifts of superconducting flux qubits deep-strongly coupled to LC oscillators, where the coupling constants are comparable to the qubit and oscillator resonance frequencies. By using two-tone spectroscopy, the energies of the six lowest levels of each circuit are determined. We find huge Lamb shifts that exceed 90% of the bare qubit frequencies and inversions of the qubits' ground and excited states when there are a finite number of photons in the oscillator. Our experimental results agree with theoretical predictions based on the quantum Rabi model.

Amyloid formation reduces protein kinase B phosphorylation in primary islet β-cells which is improved by blocking IL-1β signaling

Amyloid formation in the pancreatic islets due to aggregation of human islet amyloid polypeptide (hIAPP) contributes to reduced β-cell mass and function in type 2 diabetes (T2D) and islet transplantation. Protein kinase B (PKB) signaling plays a key role in the regulation of β-cell survival, function and proliferation. In this study, we used human and hIAPP-expressing transgenic mouse islets in culture as two ex vivo models of human islet amyloid formation to: 1. Investigate the effects of amyloid formation on PKB phosphorylation in primary islet β-cells; 2. Test if inhibition of amyloid formation and/or interleukin-1β (IL-1β) signaling in islets can restore the changes in β-cell phospho-PKB levels mediated by amyloid formation. Human and hIAPP-expressing mouse islets were cultured in elevated glucose with an amyloid inhibitor (Congo red) or embedded within collagen matrix to prevent amyloid formation. To block the IL-1β signaling, human islets were treated with an IL-1 receptor antagonist (anakinra) or a glucagon-like peptide-1 agonist (exenatide). β-cell phospho-PKB levels, proliferation, apoptosis, islet IL-1β levels and amyloid formation were assessed. Amyloid formation in both cultured human and hIAPP-expressing mouse islets reduced β-cell phospho-PKB levels and increased islet IL-1β levels, both of which were restored by prevention of amyloid formation either by the amyloid inhibitor or embedding islets in collagen matrix, resulting in improved β-cell survival. Furthermore, inhibition of IL-1β signaling by treatment with anakinra or exenatide increased β-cell phospho-PKB levels, enhanced proliferation and reduced apoptosis in amyloid forming human islets during 7-day culture. These data suggest that amyloid formation leads to reduced PKB phosphorylation in β-cells which is associated with elevated islet IL-1β levels. Inhibitors of amyloid or amyloid-induced IL-1β production may provide a new approach to restore phospho-PKB levels thereby enhance β-cell survival and proliferation in conditions associated with islet amyloid formation such as T2D and clinical islet transplantation.

Development of an Automated Computer-Controlled Islet Isolation System

Before clinical islet transplantation can become an effective and reliable treatment for type 1 diabetic patients, there must be significant improvements in the methods employed for the isolation of islets of Langerhans. We have developed an automated cell extraction system (ACES), which allows computer control of the isolation process. As well, it incorporates a novel method of recombining dissociated pancreatic tissue. Following initial system design and testing to determine the optimal system configuration, a series of 12 consecutive canine islet isolations were performed. Pancreases were perfused with collagenase via the duct and dissociated and recombined using either the standard Ricordi-based protocol (group 1, n = 6) or dissociated and recombined using the ACES system (group 2, n = 6). A total of 90.8 ± 21 x 103 islet equivalents (IE) (mean ± SEM) were recovered in group 1 vs. 99 ± 14 x 103 IE in group 2 (p = NS, student unpaired t-test). Following Ficoll purification the recovery was 56.2 ± 14 x 103 IE for group 1 vs. 54.7 ± 11 x 103 IE for group 2 (p = NS). Viability was equivalent with an 8.6-fold increase in insulin secretion for group 1 and an 8.8-fold increase for group 2 when the islets were exposed to high glucose solution supplemented with IBMX (3-isobutyl-1-methylxanthine) during static incubation. In vivo function was equivalent following transplantation of 2000 IE under the kidney capsule of alloxan-induced diabetic nude mice with five of six and five of seven mice surviving long-term (>50 days posttransplant) (groups 1 and 2, respectively). This data shows that an entirely automated pancreatic islet extraction system can result in effective canine islet recovery without compromising islet yields and viability. The ACES system has several ad van tages over the standard isolation protocol. These include: 1) computer control and monitoring over all phases of the isolation, 2) a single-use sterile disposable tubing set, and 3) a novel method of tissue recombination. Copyright © 1997 Elsevier Science Inc.

Bulk Cryopreservation of Isolated Islets of Langerhans

Current methods to isolate human islets of Langerhans are limited and multiple donors are required for successful reversal of longstanding Type 1 diabetes mellitus. Cryopreservation of isolated islets is an effective method of storing and pooling islets. Current cryopreservation protocols are cumbersome due to current practices of placing small aliquots of islets per individual freezer tube. In the present study, we examined the application of a blood freezer bag for the cryopreservation of isolated islets by slow cooling and rapid thawing. Freezing and thawing profiles generated using thermocouples placed inside a 500 mL Cryocyte (Baxter) blood freezer bag showed that a longer equilibration period at −7.4°C was necessary to consistently achieve nucleation and cooling profiles similar to those observed in glass tubes. When known numbers of rat islets were placed in the freezer bag and the cryoprotectant dimethyl sulfoxide (DMSO) was added in a stepwise fashion and removed using a sucrose dilution, the islet recovery compared with glass tubes was 92 ± 4.8 vs. 90 ± 2.3% (n = 4, p = ns, Mann-Whitney U-test). When purified canine islets were cryopreserved in a single freezer bag or in multiple glass tubes, the recovery was similar (78.8 ± 12.5% recovery for freezer bag vs. 82.3 ± 5.3% for glass tubes; n = 6, p = ns). In vitro function was equivalent for both groups. The stimulation index of insulin release during glucose perifusion (stimulated over basal insulin secretion) for canine islets cryopreserved in a freezer bag vs. glass tubes was 3.2 ± 1.0 and 2.3 ± 1.3, respectively (n = 6, p = ns). These values were significantly lower than the nonfrozen control islets (6.9 ± 2.4, p < 0.05). When 2000 canine islets cryopreserved in either a freezer bag, or glass tubes were transplanted into diabetic nude mice, the animals became and remained normoglycemic posttransplant. We conclude that the survival of freshly isolated canine islets cryopreserved in a single freezer bag is equivalent to the glass tube method. Bulk cryopreservation of islets in a single freezer bag will facilitate effective low temperature tissue banking to support ongoing clinical trials of islet transplantation.

Suppression of Human T-Cell Responses to β-Cells by Activation of B7-H4 Pathway

B7-H4, a recently described member of the B7 family of cosignal molecules, is thought to be involved in the regulation of cellular and humoral immune responses through receptors on activated T and B cells. Human islet cells express positive B7-H4 mRNA in RT-PCR assays, but not B7-H4 protein on cell surface in flow cytometric analyses. To investigate the regulatory effects of activation of the B7-H4 pathway on the function of activated T cells of patients with type 1 diabetes (T1D), we have used our in vitro human experimental system, including human β-cell antigen-specific T-cell clones and human β-cell lines CM and HP62, as well as primary islet cells. B7-H4.Ig protein was purified from the culture supernatant of 293T cells transfected by a B7-H4.Ig plasmid (pMIgV, containing a human B7-H4 cDNA and a mouse IgG2a Fc cDNA). Our preliminary studies showed that immobilized fusion protein human B7-H4.Ig (coated with 5 μg/ml for 2 h at 37°C), but not control Ig, clearly inhibited the proliferation of activated CD4+ and CD8+ T cells of patients induced by anti-CD3 antibody in CFSE assays. B7-H4.Ig also arrested cell cycle progression of T cells in G0/G1 phase and induced T-cell apoptosis as measured by BrdU-7-AAD flow cytometric analysis. To determine the cytoprotective effects of B7-H4, we developed transfectants of human β-cell lines CM and HP62 and islet cells transfected with the B7-H4.Ig plasmid, using empty vector transfectants as controls. The results demonstrate that cell-associated B7-H4.Ig expressed on human β-cells clearly inhibits the cytotoxicity of the T-cell clones to targeted human β-cells in 51Cr release cytotoxicity assays. Activation of the B7-H4 pathway may represent a novel immunotherapeutic approach to inhibit T-cell responses for the prevention of β-cell destruction in T1D.

Amyloid formation disrupts the balance between interleukin-1β and interleukin-1 receptor antagonist in human islets

Objectives

β-cell dysfunction and apoptosis associated with islet inflammation play a key role in the pathogenesis of type 2 diabetes (T2D). Growing evidence suggests that islet amyloid, formed by aggregation of human islet amyloid polypeptide (hIAPP), contributes to islet inflammation and β-cell death in T2D. We recently showed the role of interleukin-1β (IL-1β)/Fas/caspase-8 apoptotic pathway in amyloid-induced β-cell death. In this study, we used human islets in culture as an ex vivo model of amyloid formation to: (1) investigate the effects of amyloid on islet levels of the natural IL-1 receptor antagonist (IL-1Ra); (2) examine if modulating the IL-1β/IL-1Ra balance can prevent amyloid-induced β-cell Fas upregulation and apoptosis.

Methods

Isolated human islets (n = 10 donors) were cultured in elevated glucose (to form amyloid) with or without a neutralizing human IL-1β antibody for up to 7 days. Parallel studies were performed with human islets in which amyloid formation was prevented by adeno-siRNA-mediated suppression of hIAPP expression (as control). β-cell levels of IL-1Ra, Fas, apoptosis as well as islet function, insulin- and amyloid-positive areas, and IL-1Ra release were assessed.

Results

Progressive amyloid formation in human islets during culture was associated with alterations in IL-1Ra. Islet IL-1Ra levels were higher at early stages but were markedly reduced at later stages of amyloid formation. Furthermore, IL-1Ra release from human islets was reduced during 7-day culture in a time-dependent manner. These changes in IL-1Ra production and release from human islets during amyloid formation adversely correlated with islet IL-1β levels, β-cell Fas expression and apoptosis. Treatment with IL-1β neutralizing antibody markedly reduced amyloid-induced β-cell Fas expression and apoptosis, thereby improving islet β-cell survival and function during culture.

Conclusions

These data suggest that amyloid formation impairs the balance between IL-1β and IL-1Ra in islets by increasing IL-1β production and reducing IL-1Ra levels thereby promoting β-cell dysfunction and death. Restoring the IL-1β/IL-1Ra ratio may provide an effective strategy to protect islet β-cells from amyloid toxicity in T2D.

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Endogenous amyloid formation alters IL-1Ra levels in human islet β-cells.

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Amyloid impairs islet IL-1β/IL-1Ra balance by promoting IL-1β and reducing IL-1Ra.

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Restoring IL-1β/IL-1Ra ratio by blocking IL-1β protects human islets against amyloid.

Dual role of interleukin-1β in islet amyloid formation and its β-cell toxicity: Implications for type 2 diabetes and islet transplantation

AIMS

Islet amyloid, formed by aggregation of human islet amyloid polypeptide (hIAPP), contributes to β-cell failure in type 2 diabetes, cultured and transplanted islets. We previously showed that biosynthetic hIAPP aggregates induce β-cell Fas upregulation and activation of the Fas apoptotic pathway. We used cultured human and hIAPP-expressing mouse islets to investigate: (1) the role of interleukin-1β (IL-1β) in amyloid-induced Fas upregulation; and (2) the effects of IL-1β-induced β-cell dysfunction on pro-islet amyloid polypeptide (proIAPP) processing and amyloid formation.

RESEARCH DESIGN AND METHODS

Human and h IAPP -expressing mouse islets were cultured to form amyloid without or with the IL-1 receptor antagonist (IL-1Ra) anakinra, in the presence or absence of recombinant IL-1β. Human islets in which amyloid formation was prevented (amyloid inhibitor or Ad-prohIAPP-siRNA) were cultured similarly. β-cell function, apoptosis, Fas expression, caspase-8 activation, islet IL-1β, β-cell area, β-/α-cell ratio, amyloid formation, and (pro)IAPP forms were assessed.

RESULTS

hIAPP aggregates were found to increase IL-1β levels in cultured human islets that correlated with β-cell Fas upregulation, caspase-8 activation and apoptosis, all of which were reduced by IL-1Ra treatment or prevention of amyloid formation. Moreover, IL-1Ra improved culture-induced β-cell dysfunction and restored impaired proIAPP processing, leading to lower amyloid formation. IL-1β treatment potentiated impaired proIAPP processing and increased amyloid formation in cultured human and h IAPP -expressing mouse islets, which were prevented by IL-1Ra.

CONCLUSIONS

IL-1β plays a dual role by: (1) mediating amyloid-induced Fas upregulation and β-cell apoptosis; (2) inducing impaired proIAPP processing thereby potentiating amyloid formation. Blocking IL-1β may provide a new strategy to preserve β cells in conditions associated with islet amyloid formation.

IDO-Expressing Fibroblasts Protect Islet Beta Cells From Immunological Attack and Reverse Hyperglycemia in Non-Obese Diabetic Mice

Indoleamine 2,3-dioxygenase (IDO) induces immunological tolerance in physiological and pathological conditions. Therefore, we used dermal fibroblasts with stable IDO expression as a cell therapy to: (i) Investigate the factors determining the efficacy of this cell therapy for autoimmune diabetes in non-obese diabetic (NOD) mice; (ii) Scrutinize the potential immunological mechanisms. Newly diabetic NOD mice were randomly injected with either 10 × 10(6) (10M) or 15 × 10(6) (15M) IDO-expressing dermal fibroblasts. Blood glucose levels (BGLs), body weight, plasma kynurenine levels, insulitis severity, islet beta cell function, autoreactive CD8(+) T cells, Th17 cells and regulatory T cells (Tregs) were then investigated in these mice. IL-1β and cleaved caspase-3 levels were assessed in islets co-cultured with IDO-expressing fibroblasts. BGLs in 83% mice treated with 15M IDO-expressing fibroblasts recovered to normal up to 120 days. However, only 17% mice treated with 10M IDO-expressing cells were reversed to normoglycemia. A 15M IDO-expressing fibroblasts significantly reduced infiltrated immune cells in islets and recovered the functionality of remaining islet beta cells in NOD mice. Additionally, they successfully inhibited autoreactive CD8(+) T cells and Th17 cells as well as increased Tregs in different organs of NOD mice. Islet beta cells co-cultured with IDO-expressing fibroblasts had reduced IL-1β levels and cell apoptosis. Both cell number and IDO enzymatic activity contributes to the efficiency of IDO cell therapy. Optimized IDO-expressing fibroblasts successfully reverse the progression of diabetes in NOD mice through induction of Tregs as well as inhibition of beta cell specific autoreactive CD8(+) T cells and Th17 cells. J. Cell. Physiol. 231: 1964-1973, 2016. © 2016 Wiley Periodicals, Inc.

Statistical approaches and software for clustering islet cell functional heterogeneity

Worldwide efforts are underway to replace or repair lost or dysfunctional pancreatic β-cells to cure diabetes. However, it is unclear what the final product of these efforts should be, as β-cells are thought to be heterogeneous. To enable the analysis of β-cell heterogeneity in an unbiased and quantitative way, we developed model-free and model-based statistical clustering approaches, and created new software called TraceCluster. Using an example data set, we illustrate the utility of these approaches by clustering dynamic intracellular Ca(2+) responses to high glucose in ∼300 simultaneously imaged single islet cells. Using feature extraction from the Ca(2+) traces on this reference data set, we identified 2 distinct populations of cells with β-like responses to glucose. To the best of our knowledge, this report represents the first unbiased cluster-based analysis of human β-cell functional heterogeneity of simultaneous recordings. We hope that the approaches and tools described here will be helpful for those studying heterogeneity in primary islet cells, as well as excitable cells derived from embryonic stem cells or induced pluripotent cells.

Abstract P2-02-10: Circulating cells from the tumor microenvironment as liquid biopsy biomarkers alongside circulating tumor cells in metastatic breast cancer

Background: Metastasis is a multistep process that involves the shedding of tumor cells in the peripheral circulation. These Circulating Tumor Cells (CTCs) have prognostic implications in patients with metastatic breast cancer (MBC). Cancer Associated Fibroblasts (CAFs) are a major component of the breast tumor microenvironment. The reciprocal signaling between tumor cells and its microenvironment promotes carcinogenesis, invasion, and metastasis. Studies in mouse models have shown that metastatic cells can bring their own stromal components from the primary site to the site of metastasis, and that these cotraveling stromal cells provide an early growth advantage to the accompanying metastatic cancer cells. CAFs have not been identified in the peripheral circulation. Using a microfilter capture technique, we discovered non-tumor, non-immune cells in the blood of metastatic patients and identified these cells as circulating CAFs (cCAFs). The purpose of this study is to demonstrate the presence of cCAFs as a biomarker of metastasis simultaneously with CTCs in patients with MBC.

Materials and Methods: We identified 20 patients with MBC (Metastatic/MET Group) and 10 patients with cured breast cancer (Ductal carcinoma in situ or Stage I post definitive treatment with &gt;5 years of disease free survival i.e. Localized/LOC Group). A total of 7.5 ml of peripheral blood was obtained from each patient. The enumeration of CTCs and cCAFs was carried out by the microfilter capture technique. Identification of these cells was done by a triple immunofluorescence staining for pan-CK (cytokeratin), FAP (Fibroblast Activated Protein) and CD45. cCAFs were identified as CK-, FAP+, CD45- cells and CTCs as CK+, CD45- cells. Identification and confirmation of cCAF was also carried out in parallel samples by a simultaneous FAP/α-Smooth Muscle Actin staining.

Results: cCAFs were detected in 17/20 (85%) MET patients but in only 2/10 (20%) LOC patients. CTCs were detected in 20/20 (100%) MET patients and in 8/10 (80%) LOC patients. The counts of CTCs and cCAFs in MET group ranged between 1-98 (median 13.5) and 0-117 (median 4), respectively. The counts of CTCs and cCAFs in the LOC group ranged between 1-14 (median 6) and 0-2 (median 0), respectively. For patients with exhibited cCAFs, 2/10 LOC and 5/17 MET patients had cCAFs counts of 2 or less. Although the sample size was small, patients exhibiting cCAFs (odds ratio=22.67, 95% CI: 3.14-163.63, p=0.002) were more likely to be in MET group than LOC group.

Conclusion: This is the first demonstration that CAFs, the predominant mesenchymal cell in the breast tumor microenvironment, are shed into the circulation and can be identified and enumerated as cCAFs in MBC patients along with CTCs. There was a clear difference in the numbers of CTCs and cCAFs levels between the MET and the LOC groups suggesting that CTCs and cCAFs are associated with advanced stage disease. While most patients, both in the LOC and MET group, exhibited CTCs, very few LOC patients exhibited cCAFs. We suggest that cCAFs could independently or along with CTCs serve as liquid biopsy biomarkers of metastasis. Validation of these findings in a larger cohort of patients will be presented during the meeting.

Citation Format: Parajuli R, Ao Z, Shah SH, Sengul TK, Lippman ME, Datar R, El-Ashry D. Circulating cells from the tumor microenvironment as liquid biopsy biomarkers alongside circulating tumor cells in metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-10.

Quantitative description of collagen fibre network on trabecular bone surfaces based on AFM imaging

The collagen fibre network is an important part of extracellular matrix (ECM) on trabecular bone surface. The geometry features of the network can provide us insights into its physical and physiological properties. However, previous researches have not focused on the geometry and the quantitative description of the collagen fibre network on trabecular bone surface. In this study,we developed a procedure to quantitatively describe the network and verified the validity of the procedure. The experiment proceeds as follow. Atomic force microscopy (AFM) was used to acquire submicron resolution images of the trabecular surface. Then, an image analysing procedure was built to extract important parameters, including, fibre orientation, fibre density, fibre width, fibre crossing numbers, the number of holes formed by fibre s, and the area of holes from AFM images. In order to verify the validity of the parameters extracted by image analysing methods, we adopted two other methods, which are statistical geometry model and computer simulation, to calculate those same parameters and check the consistency of the three methods' results. Statistical tests indicate that there is no significant difference between three groups. We conclude that, (a) the ECM on trabecular surface mainly consists of random collagen fibre network with oriented fibres; (b) our method based on image analysing can be used to characterize quantitative geometry features of the collagen fibre network effectively. This method may provide a basis for quantitative investigating the architecture and function of collagen fibre network.

Oligosaccharides affect performance and gut development of broiler chickens

The effects of oligosaccharide supplementation on the growth performance, flock uniformity and GIT development of broiler chickens were investigated. Four diets, one negative control, one positive control supplemented with zinc-bacitracin, and two test diets supplemented with mannoligosaccharide (MOS) and fructooligosaccharide (FOS), were used for the experiment. Birds given MOS or FOS had improved body weight (BW) and feed efficiency (FCR), compared to those fed the negative control diet during the 35-d trial period. The effect on FCR became less apparent when the birds got older. FOS and MOS supplementation reduced the pancreas weight as a percentage of BW, with an effect similar to that of the antibiotic, at 35 d of age. Birds given MOS tended to have a heavier bursa (p = 0.164) and lower spleen/bursa weight ratio (p = 0.102) at 35 d of age. MOS and Zn-bacitracin showed a clear improvement on flock uniformity, compared to FOS. The mortality rate was not affected by FOS or MOS.

Effects of Dietary Additives and Early Feeding on Performance, Gut Development and Immune Status of Broiler Chickens Challenged with Clostridium perfringens

The effects of dietary additives and holding time on resistance and resilience of broiler chickens to Clostridium perfringens challenge were investigated by offering four dietary treatments. These were a negative control (basal), a positive control (Zn-bacitracin) and two dietary additives, mannanoligosaccharides (MOS), and acidifier. Two holding times included (a) immediate access to feed and water post hatch (FED) and (b) access to both feed and water 48 h post hatch (HELD). Chicks fed Zn-bacitracin had no intestinal lesions attributed to necrotic enteritis (NE), whereas chicks fed both MOS or acidifier showed signs of NE related lesions. All dietary treatments were effective in reducing the numbers of C. perfringens in the ileum post challenge. The FED chicks had heavier body weight and numerically lower mortality. The FED chicks also showed stronger immune responses to NE challenge, showing enhanced (p<0.05) proliferation of T-cells. Early feeding of the MOS supplemented diet increased (p<0.05) IL-6 production. The relative bursa weight of the FED chicks was heavier at d 21 (p<0.05). All the additives increased the relative spleen weight of the HELD chicks at d 14 (p<0.05). The FED chicks had increased villus height and reduced crypt depth, and hence an increased villus/crypt ratio, especially in the jejunum at d 14 (p<0.05). The same was true for the HELD chicks given dietary additives (p<0.05). It may be concluded that the chicks with early access to dietary additives showed enhanced immune response and gut development, under C. perfringens challenge. The findings of this study shed light on managerial and nutritional strategies that could be used to prevent NE in the broiler industry without the use of in-feed antibiotics.

The role of caspase-8 in amyloid-induced beta cell death in human and mouse islets

AIMS/HYPOTHESIS

Reduced beta cell mass due to increased beta cell apoptosis is a key defect in type 2 diabetes. Islet amyloid, formed by the aggregation of human islet amyloid polypeptide (hIAPP), contributes to beta cell death in type 2 diabetes and in islet grafts in patients with type 1 diabetes. In this study, we used human islets and hIAPP-expressing mouse islets with beta cell Casp8 deletion to (1) investigate the role of caspase-8 in amyloid-induced beta cell apoptosis and (2) test whether caspase-8 inhibition protects beta cells from amyloid toxicity.

METHODS

Human islet cells were cultured with hIAPP alone, or with caspase-8, Fas or amyloid inhibitors. Human islets and wild-type or hIAPP-expressing mouse islets with or without caspase-8 expression (generated using a Cre/loxP system) were cultured to form amyloid. Caspase-8 and -3 activation, Fas and FLICE inhibitory protein (FLIP) expression, islet beta cell and amyloid area, IL-1β levels, and the beta:alpha cell ratio were assessed.

RESULTS

hIAPP treatment induced activation of caspase-8 and -3 in islet beta cells (via Fas upregulation), resulting in apoptosis, which was markedly reduced by blocking caspase-8, Fas or amyloid. Amyloid formation in cultured human and hIAPP-expressing mouse islets induced caspase-8 activation, which was associated with Fas upregulation and elevated islet IL-1β levels. hIAPP-expressing mouse islets with Casp8 deletion had comparable amyloid, IL-1β and Fas levels with those expressing hIAPP and Casp8, but markedly lower beta cell apoptosis, higher beta:alpha cell ratio, greater beta cell area, and enhanced beta cell function.

CONCLUSIONS/INTERPRETATION

Beta cell Fas upregulation by endogenously produced and exogenously applied hIAPP aggregates promotes caspase-8 activation, resulting in beta cell apoptosis. The prevention of amyloid-induced caspase-8 activation enhances beta cell survival and function in islets.

The glucagon-like peptide-1 receptor agonist exenatide restores impaired pro-islet amyloid polypeptide processing in cultured human islets: implications in type 2 diabetes and islet transplantation

AIMS/HYPOTHESIS

Islet amyloid, formed by aggregation of human islet amyloid polypeptide (hIAPP), is associated with beta cell death in type 2 diabetes as well as in cultured and transplanted human islets. Impaired prohIAPP processing due to beta cell dysfunction is implicated in hIAPP aggregation. We examined whether the glucagon-like peptide-1 receptor (GLP-1R) agonist exenatide can restore impaired prohIAPP processing and reduce hIAPP aggregation in cultured human islets and preserve beta cell function/mass during culture conditions used in clinical islet transplantation.

METHODS

Isolated human islets (n = 10 donors) were cultured with or without exenatide in normal or elevated glucose for 2 or 7 days. Beta cell apoptosis, proliferation, mass, function, cJUN N-terminal kinase (JNK) and protein kinase B (PKB) activation and amyloid formation were assessed. ProhIAPP, its intermediates and mature hIAPP were detected.

RESULTS

Exenatide-treated islets had markedly lower JNK and caspase-3 activation and beta cell apoptosis, resulting in higher beta/alpha cell ratio and beta cell area than non-treated cultured islets. Exenatide improved beta cell function, manifested as higher insulin response to glucose and insulin content, compared with non-treated cultured islets. Phospho-PKB immunoreactivity was detectable in exenatide-treated but not untreated cultured islets. Islet culture caused impaired prohIAPP processing with decreased mature hIAPP and increased NH(2)-terminally unprocessed prohIAPP levels resulting in higher release of immature hIAPP. Exenatide restored prohIAPP processing and reduced hIAPP aggregation in cultured islets.

CONCLUSIONS/INTERPRETATION

Exenatide treatment enhances survival and function of cultured human islets and restores impaired prohIAPP processing in normal and elevated glucose conditions thereby reducing hIAPP aggregation. GLP-1R agonists may preserve beta cells in conditions associated with islet amyloid formation.

Three-dimensional scaffolds reduce islet amyloid formation and enhance survival and function of cultured human islets

Islet transplantation provides a promising approach for treatment of type 1 diabetes mellitus. Amyloid formation and loss of extracellular matrix are two nonimmune factors contributing to death of isolated human islets. We tested the effects of two types of three-dimensional scaffolds, collagen matrix (CM) and fibroblast-populated collagen matrix (FPCM), on amyloid formation, viability, and function of isolated islets. Islets from cadaveric donors were cultured in FPCM, CM, or two-dimensional plate (2D) for 7 days. After 7 days, compared with the 2D culture condition, CM and FPCM markedly reduced amyloid formation of cultured islets and decreased apoptotic β-cell rate by ∼75%. IL-1β and Fas levels were also reduced in scaffold-embedded islets. Furthermore, β/α cell ratios were increased by ∼18% and ∼36% in CM- and FPCM-embedded islets, respectively. Insulin content and insulin response to elevated glucose were also enhanced by both three-dimensional scaffolds. Moreover, culture in CM and FPCM (but not 2D) preserved insulin, GLUT-2, and PDX-1 mRNA expression. FPCM-embedded islets had significantly higher insulin response and lower amyloid formation than CM-embedded islets. These findings suggest that three-dimensional scaffolds reduce amyloid formation and improve viability and function of human islets in vitro, and that CM and fibroblasts have additive effects in enhancing islet function and reducing amyloid formation. Using this strategy is likely to improve outcome in human islet transplantation.

Maturation of human embryonic stem cell-derived pancreatic progenitors into functional islets capable of treating pre-existing diabetes in mice

Diabetes is a chronic debilitating disease that results from insufficient production of insulin from pancreatic β-cells. Islet cell replacement can effectively treat diabetes but is currently severely limited by the reliance upon cadaveric donor tissue. We have developed a protocol to efficiently differentiate commercially available human embryonic stem cells (hESCs) in vitro into a highly enriched PDX1+ pancreatic progenitor cell population that further develops in vivo to mature pancreatic endocrine cells. Immature pancreatic precursor cells were transplanted into immunodeficient mice with streptozotocin-induced diabetes, and glycemia was initially controlled with exogenous insulin. As graft-derived insulin levels increased over time, diabetic mice were weaned from exogenous insulin and human C-peptide secretion was eventually regulated by meal and glucose challenges. Similar differentiation of pancreatic precursor cells was observed after transplant in immunodeficient rats. Throughout the in vivo maturation period hESC-derived endocrine cells exhibited gene and protein expression profiles that were remarkably similar to the developing human fetal pancreas. Our findings support the feasibility of using differentiated hESCs as an alternative to cadaveric islets for treating patients with diabetes.

TRAIL-engineered pancreas-derived mesenchymal stem cells: characterization and cytotoxic effects on pancreatic cancer cells

Mesenchymal stem cells (MSCs) have attracted great interest in cancer therapy owing to their tumor-oriented homing capacity and the feasibility of autologous transplantation. Currently, pancreatic cancer patients face a very poor prognosis, primarily due to the lack of therapeutic strategies with an effective degree of specificity. Anticancer gene-engineered MSCs specifically target tumor sites and can produce anticancer agents locally and constantly. This study was performed to characterize pancreas-derived MSCs and investigate the effects of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-engineered MSCs on pancreatic cancer cells under different culture conditions. Pancreas-derived MSCs exhibited positive expression on CD44, CD73, CD95, CD105, negative on CD34 and differentiated into adipogenic and osteogenic cells. TRAIL expression was assessed by both enzyme-linked immunosorbent assay and western blot analysis. Different patterns of TRAIL receptor expression were observed on the pancreatic cancer cell lines, including PANC1, HP62, ASPC1, TRM6 and BXPC3. Cell viability was assessed using a real-time monitoring system. Pancreatic cancer cell death was proportionally related to conditioned media from MSC(nsTRAIL) and MSC(stTRAIL). The results suggest that MSCs exhibit intrinsic inhibition of pancreatic cancer cells and that this effect can be potentiated by TRAIL-transfection on death receptor-bearing cell types.

Blockade of both B7-H4 and CTLA-4 co-signaling pathways enhances mouse islet allograft survival

Costimulation blockade is an effective way to prevent allograft rejection. In this study, we tested the efficacy of two negative co-signaling molecules in protecting islet allograft function. We used local expression of B7-H4 by adenoviral transduction of islets (Ad-B7-H4) and systemic administration of CTLA-4.Ig to investigate the outcomes of allograft survival. Five groups of streptozotocin-induced diabetic C57BL/6 mice received 400 islets each from BALB/c donors. The groups consisted of control (G1); CTLA-4.Ig (G2); Ad-LacZ (G3); Ad-B7-H4 (G4); and Ad-B7-H4 and CTLA-4.Ig combined (G5). G1 and G3 developed graft failure on average of two weeks. G2, G4 and G5 survived for 43.8 ± 34.8, 54.7 ± 31.2 and 77.8 ± 21.5 d, respectively. Activated T and B cells in the lymph nodes were significantly controlled by CTLA-4.Ig treatment. Significantly reduced infiltrates were also detected in the allografts of G2 compared with G1. By contrast, B7-H4 significantly inhibited Th1-associated IFN-gamma secretion in the early stage and increased Foxp3 (+) T cells in the long-term surviving allografts. Our study suggests that CTLA-4 and B7-H4 inhibit alloimmune responses through distinct mechanisms, and that combination therapy which activates two negative co-signaling pathways can further enhance islet allograft survival.

Immunohistochemical characterisation of cells co-producing insulin and glucagon in the developing human pancreas

AIMS/HYPOTHESIS

In adult human islets, insulin and glucagon production is largely restricted to individual cell populations. The production of these hormones is less segregated during development and during the differentiation of human pluripotent stem cells towards pancreatic lineages. We therefore sought to characterise the transcription factor profile of these cells that co-produce insulin and glucagon in the developing human pancreas, and thus to gain insight into their potential fate during normal pancreas development.

METHODS

An immunohistochemical analysis was performed on human pancreas sections from fetal donors aged 9 to 21 weeks and from adult donors between the ages of 17 and 55 years.

RESULTS

Endocrine cells were observed within the pancreas at all ages examined, with cells co-producing insulin and glucagon observed as early as 9 weeks of fetal age. The population of cells that co-produce insulin and glucagon generally decreased in prevalence with age, with negligible numbers in adult pancreas. From 9 to 16 weeks, the population of glucagon-only cells increased, while the insulin-only cells decreased in abundance. Cells that co-produced insulin and glucagon also produced the alpha cell transcription factor, aristaless related homeobox (ARX), and lacked the beta cell transcription factors pancreatic and duodenal homeobox 1 (PDX1), NK6 homeobox 1 (NKX6.1) and v-maf musculoaponeurotic fibrosarcoma oncogene homologue A (MAFA).

CONCLUSIONS/INTERPRETATION

Our results indicate that cells co-producing insulin and glucagon in the developing human pancreas share a transcription factor profile that is similar to that of mature alpha cells and suggest that some maturing alpha cells briefly exhibit ectopic insulin expression. Thus cells that co-produce insulin and glucagon may represent a transient cell population, which gives rise to mature alpha cells.

B7-H4 Treatment of T Cells Inhibits ERK, JNK, p38, and AKT Activation

B7-H4 is a newly identified B7 homolog that plays an important role in maintaining T-cell homeostasis by inhibiting T-cell proliferation and lymphokine-secretion. In this study, we investigated the signal transduction pathways inhibited by B7-H4 engagement in mouse T cells. We found that treatment of CD3(+) T cells with a B7-H4.Ig fusion protein inhibits anti-CD3 elicited T-cell receptor (TCR)/CD28 signaling events, including phosphorylation of the MAP kinases, ERK, p38, and JNK. B7-H4.Ig treatment also inhibited the phosphorylation of AKT kinase and impaired its kinase activity as assessed by the phosphorylation of its endogenous substrate GSK-3. Expression of IL-2 is also reduced by B7-H4. In contrast, the phosphorylation state of the TCR proximal tyrosine kinases ZAP70 and lymphocyte-specific protein tyrosine kinase (LCK) are not affected by B7-H4 ligation. These results indicate that B7-H4 inhibits T-cell proliferation and IL-2 production through interfering with activation of ERK, JNK, and AKT, but not of ZAP70 or LCK.

Generation of transplantable Beta cells for patient-specific cell therapy

Islet cell transplantation offers a potential cure for type 1 diabetes, but it is challenged by insufficient donor tissue and side effects of current immunosuppressive drugs. Therefore, alternative sources of insulin-producing cells and isletfriendly immunosuppression are required to increase the efficiency and safety of this procedure. Beta cells can be transdifferentiated from precursors or another heterologous (non-beta-cell) source. Recent advances in beta cell regeneration from somatic cells such as fibroblasts could circumvent the usage of immunosuppressive drugs. Therefore, generation of patient-specific beta cells provides the potential of an evolutionary treatment for patients with diabetes.

Early treatment of NOD mice with B7-H4 reduces the incidence of autoimmune diabetes

OBJECTIVE

Autoimmune diabetes is a T cell-mediated disease in which insulin-producing β-cells are destroyed. Autoreactive T cells play a central role in mediating β-cell destruction. B7-H4 is a negative cosignaling molecule that downregulates T-cell responses. In this study, we aim to determine the role of B7-H4 on regulation of β-cell-specific autoimmune responses.

RESEARCH DESIGN AND METHODS

Prediabetic (aged 3 weeks) female NOD mice (group 1, n = 21) were treated with intraperitoneal injections of B7-H4.Ig at 7.5 mg/kg, with the same amount of mouse IgG (group 2, n = 24), or with no protein injections (group 3, n = 24), every 3 days for 12 weeks.

RESULTS

B7-H4.Ig reduced the incidence of autoimmune diabetes, compared with the control groups (diabetic mice 28.6% of group 1, 66.7% of group 2 [P = 0.0081], and 70.8% of group 3 [group 1 vs. 3, P = 0.0035]). Histological analysis revealed that B7-H4 treatment did not block islet infiltration but rather suppressed further infiltrates after 9 weeks of treatment (group 1 vs. 2, P = 0.0003). B7-H4 treatment also reduced T-cell proliferation in response to GAD65 stimulation ex vivo. The reduction of diabetes is not due to inhibition of activated T cells in the periphery but rather to a transient increase of Foxp3(+) CD4(+) T-cell population at one week posttreatment (12.88 ± 1.29 vs. 11.58 ± 1.46%; n = 8; P = 0.03).

CONCLUSIONS

Our data demonstrate the protective role of B7-H4 in the development of autoimmune diabetes, suggesting a potential means of preventing type 1 diabetes by targeting the B7-H4 pathway.

Musashi expression in β-cells coordinates insulin expression, apoptosis and proliferation in response to endoplasmic reticulum stress in diabetes

Diabetes is associated with the death and dysfunction of insulin-producing pancreatic β-cells. In other systems, Musashi genes regulate cell fate via Notch signaling, which we recently showed regulates β-cell survival. Here we show for the first time that human and mouse adult islet cells express mRNA and protein of both Musashi isoforms, as well Numb/Notch/Hes/neurogenin-3 pathway components. Musashi expression was observed in insulin/glucagon double-positive cells during human fetal development and increased during directed differentiation of human embryonic stem cells (hESCs) to the pancreatic lineage. De-differentiation of β-cells with activin A increased Msi1 expression. Endoplasmic reticulum (ER) stress increased Msi2 and Hes1, while it decreased Ins1 and Ins2 expression, revealing a molecular link between ER stress and β-cell dedifferentiation in type 2 diabetes. These effects were independent of changes in Numb protein levels and Notch activation. Overexpression of MSI1 was sufficient to increase Hes1, stimulate proliferation, inhibit apoptosis and reduce insulin expression, whereas Msi1 knockdown had the converse effects on proliferation and insulin expression. Overexpression of MSI2 resulted in a decrease in MSI1 expression. Taken together, these results demonstrate overlapping, but distinct roles for Musashi-1 and Musashi-2 in the control of insulin expression and β-cell proliferation. Our data also suggest that Musashi is a novel link between ER stress and the compensatory β-cell proliferation and the loss of β-cell gene expression seen in specific phases of the progression to type 2 diabetes.

B7-H4 induces donor-specific tolerance in mouse islet allografts

Negative cosignaling molecules play an important role in regulating T-cell responses to alloantigen stimulation. We recently reported that adenoviral-mediated transduction of islet allografts with B7-H4 inhibits allograft rejection. In this study, we investigate the mechanism for B7-H4-induced prolongation of mouse islet allograft survival. Streptozotocin-induced diabetic C57BL/6 mice were rendered normoglycemic by renal subcapsular implants of B7-H4-transduced BALB/c islets. Grafts and spleens were removed after days 2, 10, and 60 (n = 8 each) for characterization of kinetics of Foxp3 and interleukin 10 (IL-10) expression. Mixed lymphocyte reaction (MLR) was done at day 60. Ten mice were subjected to nephrectomy at 60 days and then five were implanted with secondary BALB/c islets and five were given third-party CBA/J islets. An increase in Foxp3 and IL-10 mRNA expression was detected in recipients' spleens at day 60 and this was associated with increased quantities of Foxp3(+) cells. Splenocytes at day 60 showed hyporesponsiveness during MLR to alloantigen stimulation. Proliferation was partially restored after CD25(+) T-cell depletion. Secondary BALB/c islets survived for 79 ± 29 days compared with 21 ± 3.6 days for CBA/J islets (p < 0.001). Local expression of B7-H4 induces long-term unresponsiveness to donor-specific alloantigens, and is associated with T regulatory cells, suggesting the development of tolerance.

Pancreatic β-cell prosurvival effects of the incretin hormones involve post-translational modification of Kv2.1 delayed rectifier channels

Glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are the major incretin hormones that exert insulinotropic and anti-apoptotic actions on pancreatic β-cells. Insulinotropic actions of the incretins involve modulation of voltage-gated potassium (Kv) channels. In multiple cell types, Kv channel activity has been implicated in cell volume changes accompanying initiation of the apoptotic program. Focusing on Kv2.1, we examined whether regulation of Kv channels in β-cells contributes to the prosurvival effects of incretins. Overexpression of Kv2.1 in INS-1 β-cells potentiated apoptosis in response to mitochondrial and ER stress and, conversely, co-stimulation with GIP/GLP-1 uncoupled this potentiation, suppressing apoptosis. In parallel, incretins promoted phosphorylation and acetylation of Kv2.1 via pathways involving protein kinase A (PKA)/mitogen- and stress-activated kinase-1 (MSK-1) and histone acetyltransferase (HAT)/histone deacetylase (HDAC). Further studies demonstrated that acetylation of Kv2.1 was mediated by incretin actions on nuclear/cytoplasmic shuttling of CREB binding protein (CBP) and its interaction with Kv2.1. Regulation of β-cell survival by GIP and GLP-1 therefore involves post-translational modifications (PTMs) of Kv channels by PKA/MSK-1 and HAT/HDAC. This appears to be the first demonstration of modulation of delayed rectifier Kv channels contributing to the β-cell prosurvival effects of incretins and of 7-transmembrane G protein-coupled receptor (GPCR)-stimulated export of a nuclear lysine acetyltransferase that regulates cell surface ion channel function.

Fibroblast populated collagen matrix promotes islet survival and reduces the number of islets required for diabetes reversal

Islet transplantation represents a viable treatment for type 1 diabetes. However, due to loss of substantial mass of islets early after transplantation, islets from two or more donors are required to achieve insulin independence. Islet-extracellular matrix disengagement, which occurs during islet isolation process, leads to subsequent islet cell apoptosis and is an important contributing factor to early islet loss. In this study, we developed a fibroblast populated collagen matrix (FPCM) as a novel scaffold to improve islet cell viability and function post-transplantation. FPCM was developed by embedding fibroblasts within type-I collagen and used as scaffold for islet grafts. Viability and insulin secretory function of islets embedded within FPCM was evaluated in vitro and in a syngeneic murine islet transplantation model. Islets embedded within acellular matrix or naked islets were used as control. Islet cell survival and function was markedly improved particularly after embedding within FPCM. The composite scaffold significantly promoted islet isograft survival and reduced the critical islet mass required for diabetes reversal by half (from 200 to 100 islets per recipient). Fibroblast embedded within FPCM produced fibronectin and growth factors and induced islet cell proliferation. No evidence of fibroblast over-growth within composite grafts was noticed. These results confirm that FPCM significantly promotes islet viability and functionality, enhances engraftment of islet grafts and decreases the critical islet mass needed to reverse hyperglycemia. This promising finding offers a new approach to reducing the number of islet donors per recipient and improving islet transplant outcome.

Production of functional glucagon-secreting α-cells from human embryonic stem cells

OBJECTIVE

Differentiation of human embryonic stem (hES) cells to fully developed cell types holds great therapeutic promise. Despite significant progress, the conversion of hES cells to stable, fully differentiated endocrine cells that exhibit physiologically regulated hormone secretion has not yet been achieved. Here we describe an efficient differentiation protocol for the in vitro conversion of hES cells to functional glucagon-producing α- cells.

RESEARCH DESIGN AND METHODS

Using a combination of small molecule screening and empirical testing, we developed a six-stage differentiation protocol for creating functional α-cells. An extensive in vitro and in vivo characterization of the differentiated cells was performed.

RESULTS

A high rate of synaptophysin expression (>75%) and robust expression of glucagon and the α-cell transcription factor ARX was achieved. After a transient polyhormonal state in which cells coexpress glucagon and insulin, maturation in vitro or in vivo resulted in depletion of insulin and other β-cell markers with concomitant enrichment of α-cell markers. After transplantation, these cells secreted fully processed, biologically active glucagon in response to physiologic stimuli including prolonged fasting and amino acid challenge. Moreover, glucagon release from transplanted cells was sufficient to reduce demand for pancreatic glucagon, resulting in a significant decrease in pancreatic α-cell mass.

CONCLUSIONS

These results indicate that fully differentiated pancreatic endocrine cells can be created via stepwise differentiation of hES cells. These cells may serve as a useful screening tool for the identification of compounds that modulate glucagon secretion as well as those that promote the transdifferentiation of α-cells to β-cells.

Differences between amyloid toxicity in alpha and beta cells in human and mouse islets and the role of caspase-3

AIMS/HYPOTHESIS

Type 2 diabetes is characterised by decreased beta cell mass and islet amyloid formation. Islet amyloid formed by aggregation of human islet amyloid polypeptide (hIAPP) is associated with beta cell apoptosis. We used human and transgenic mouse islets in culture to examine whether deletion of caspase-3 protects islets from apoptosis induced by endogenously produced and exogenously applied hIAPP and compared hIAPP toxicity in islet alpha and beta cells.

METHODS

Human and wild-type or caspase-3 knockout mouse islet cells were treated with hIAPP. Rat insulinoma INS-1 cells were similarly cultured with hIAPP and the amyloid inhibitor Congo Red or caspase-3 inhibitor. Human and hIAPP-expressing caspase-3 knockout mouse islets were cultured to form amyloid fibrils and assessed for beta and alpha cell apoptosis, beta cell function and caspase-3 activation.

RESULTS

hIAPP-treated INS-1 cells had increased caspase-3 activation and apoptosis, both of which were reduced by inhibitors of amyloid or caspase-3. Similarly, hIAPP-treated human and mouse islet beta cells had elevated active caspase-3- and TUNEL-positive cells, whereas mouse islet cells lacking caspase-3 had markedly lower beta cell but comparable alpha cell apoptosis. During culture, human islets that formed amyloid had higher active caspase-3- and TUNEL-positive beta cells than those without detectable amyloid. Finally, cultured hIAPP-expressing mouse islets lacking caspase-3 had markedly lower beta cell apoptosis than those expressing caspase-3, associated with an increase in islet beta cell/alpha cell ratio, insulin content and glucose response.

CONCLUSIONS/INTERPRETATION

Prevention of caspase-3 activation protects islet beta cells from apoptosis induced by fibrillogenesis of endogenously secreted and exogenously applied hIAPP. Islet beta cells are more susceptible to hIAPP toxicity than alpha cells cultured under the same conditions.

Glucose-dependent insulinotropic polypeptide is expressed in pancreatic islet alpha-cells and promotes insulin secretion

BACKGROUND & AIMS

Glucose-dependent insulinotropic polypeptide (GIP) and the proglucagon product glucagon-like peptide-1 (GLP-1) are gastrointestinal hormones that are released in response to nutrient intake and promote insulin secretion. Interestingly, a subset of enteroendocrine cells express both GIP and GLP-1. We sought to determine whether GIP also might be co-expressed with proglucagon in pancreatic alpha-cells.

METHODS

We assessed GIP expression via reverse-transcription polymerase chain reaction, in situ hybridization, and immunohistochemistry. We developed a novel bioassay to measure GIP release from isolated islets, compared the biological activities of full-length and truncated GIP, and assessed the impact of immunoneutralization of islet GIP on glucose-stimulated insulin secretion in isolated islets.

RESULTS

GIP messenger RNA was present in mouse islets; GIP protein localized to islet alpha-cells of mouse, human, and snake pancreas, based on immunohistochemical analyses. However, using a C-terminal GIP antibody, immunoreactivity was detected in islets from prohormone convertase (PC) 2 knockout but not wild-type mice. Bioactive GIP was secreted from mouse and human islets after arginine stimulation. In the perfused mouse pancreas, GIP(1-42) and amidated GIP(1-30) had equipotent insulinotropic actions. Finally, immunoneutralization of GIP secreted by isolated islets decreased glucose-stimulated insulin secretion.

CONCLUSIONS

GIP is expressed in and secreted from pancreatic islets; in alpha-cells, PC2 processes proGIP to yield a truncated but bioactive form of GIP that differs from the PC1/3-derived form from K-cells. Islet-derived GIP promotes islet glucose competence and also could support islet development and/or survival.

Suppression of p38 MAPK and JNK via Akt-mediated inhibition of apoptosis signal-regulating kinase 1 constitutes a core component of the beta-cell pro-survival effects of glucose-dependent insulinotropic polypeptide

Glucose-dependent insulinotropic polypeptide (GIP) potentiates glucose-stimulated insulin secretion, insulin biosynthesis, and beta-cell proliferation and survival. In previous studies GIP was shown to promote beta-cell survival by modulating the activity of multiple signaling modules and regulating gene transcription of pro- and anti-apoptotic bcl-2 family proteins. We have now evaluated the mechanisms by which GIP regulates the dynamic interactions between cytoplasmic bcl-2 family members and the mitochondria in INS-1 cells during apoptosis induced by treatment with staurosporine (STS), an activator of the mitochondria-mediated apoptotic pathway. STS induced translocation of bad and bimEL, activation of mitochondrial bax, release of mitochondrial cytochrome c, cleavage of caspase-3, and apoptosis. Each response was significantly diminished by GIP. Using selective enzyme inhibitors, overexpression of dominant-negative Akt, and Akt siRNA, it was demonstrated that GIP promoted beta-cell survival via Akt-dependent suppression of p38 MAPK and JNK and that combined inhibition was sufficient to explain the entire pro-survival responses to GIP during STS treatment. This signaling pathway also explained the pro-survival effects of GIP on INS-1 cells exposed to two other promoters of stress: thapsigargin (endoplasmic reticulum stress) and etoposide (genotoxic stress). Importantly, we discovered that GIP suppressed p38 MAPK and JNK via Akt-mediated changes in the phosphorylation state of the apoptosis signal-regulating kinase 1 in INS-1 cells and human islets, resulting in inhibition of its activity. Inhibition of apoptosis by GIP is therefore mediated via a key pathway involving Akt-dependent inhibition of apoptosis signal-regulating kinase 1, which subsequently prevents the pro-apoptotic actions of p38 MAPK and JNK.

Do immunotherapy and beta cell replacement play a synergistic role in the treatment of type 1 diabetes?

Type 1 diabetes (T1D) is the result of the autoimmune response against pancreatic insulin-producing ss-cells. Its ultimate consequence is beta-cell insufficiency-mediated dysregulation of blood glucose control. In terms of T1D treatment, immunotherapy addresses the cause of T1D, mainly through re-setting the balance between autoimmunity and regulatory mechanisms. Regulatory T cells play an important role in this immune intervention. An alternative T1D treatment is beta-cell replacement, which can reverse the consequence of the disease by replacing destroyed beta-cells in the diabetic pancreas. The applicable insulin-producing cells can be directly obtained from islet transplantation or generated from other cell sources such as autologous adult stem cells, embryonic stem cells, and induced pluripotent stem cells. In this review, we summarize the recent research progress and analyze the possible advantages and disadvantages of these two therapeutic options especially focusing on the potential synergistic effect on T1D treatment. Exploring the optimal combination of immunotherapy and beta-cell replacement will pave the way to the most effective cure for this devastating disease.

Different effects of FK506, rapamycin, and mycophenolate mofetil on glucose-stimulated insulin release and apoptosis in human islets

Pancreatic islet transplantation has the potential to be an effective treatment for type 1 diabetes mellitus. While recent improvements have improved 1-year outcomes, follow-up studies show a persistent loss of graft function/survival over 5 years. One possible cause of islet transplant failure is the immunosuppressant regimen required to prevent alloimmune graft rejection. Although there is evidence from separate studies, mostly in rodents and cell lines, that FK506 (tacrolimus), rapamycin (sirolimus), and mycophenolate mofetil (MMF; CellCept) can damage pancreatic beta-cells, there have been few side-by-side, multiparameter comparisons of the effects of these drugs on human islets. In the present study, we show that 24-h exposure to FK506 or MMF impairs glucose-stimulated insulin secretion in human islets. FK506 had acute and direct effects on insulin exocytosis, whereas MMF did not. FK506, but not MMF, impaired human islet graft function in diabetic NOD*scid mice. All of the immunosuppressants tested in vitro increased caspase-3 cleavage and caspase-3 activity, whereas MMF induced ER-stress to the greatest degree. Treating human islets with the GLP-1 agonist exenatide ameliorated the immunosuppressant-induced defects in glucose-stimulated insulin release. Together, our results demonstrate that immunosuppressants impair human beta-cell function and survival, and that these defects can be circumvented to a certain extent with exenatide treatment.

The effect of medical therapy and islet cell transplantation on diabetic nephropathy: an interim report

BACKGROUND

The effect of islet cell transplantation (ICT) on renal function in type 1 diabetes is uncertain and some recent studies report a significant decline in estimated glomerular filtration rate (GFR) and worsening of albuminuria.

METHODS

We are conducting a prospective crossover study comparing medical treatment with islet transplantation on the progression of diabetic complications, including renal function. The primary endpoint is change in GFR measured by Tc-diethylenetriaminepentaacetate with secondary endpoints including estimated GFR and albumin excretion.

RESULTS

We have followed 21 patients after islet transplantation a median of 29 months (range 13-45) and compared their results with medically treated patients followed a median 29.5 months (range 13-56). There is no difference in the rate of decline in measured GFR between medically treated patients (-0.35+/-0.89; 95% CI: -0.57 to -0.13 mL/min/month/1.73 m) and those after ICT (-0.31+/-1.18; 95% CI: -0.61 to -0.01) and neither is significantly different from that expected for the general population. The rate of decline in our estimated GFR results is lower than that reported in other studies and we did not find any worsening of albuminuria.

CONCLUSIONS

We do not find evidence of worsening of renal function after islet transplantation compared with medically treated patients.

The novel endocannabinoid receptor GPR55 is activated by atypical cannabinoids but does not mediate their vasodilator effects

BACKGROUND AND PURPOSE

Atypical cannabinoids are thought to cause vasodilatation through an as-yet unidentified 'CBx' receptor. Recent reports suggest GPR55 is an atypical cannabinoid receptor, making it a candidate for the vasodilator 'CBx' receptor. The purpose of the present study was to test the hypothesis that human recombinant GPR55 is activated by atypical cannabinoids and mediates vasodilator responses to these agents.

EXPERIMENTAL APPROACH

Human recombinant GPR55 was expressed in HEK293T cells and specific GTPgammaS activity was monitored as an index of receptor activation. In GPR55-deficient and wild-type littermate control mice, in vivo blood pressure measurement and isolated resistance artery myography were used to determine GPR55 dependence of atypical cannabinoid-induced haemodynamic and vasodilator responses.

KEY RESULTS

Atypical cannabinoids O-1602 and abnormal cannabidiol both stimulated GPR55-dependent GTPgammaS activity (EC50 approximately 2 nM), whereas the CB1 and CB2-selective agonist WIN 55,212-2 showed no effect in GPR55-expressing HEK293T cell membranes. Baseline mean arterial pressure and heart rate were not different between WT and GPR55 KO mice. The blood pressure-lowering response to abnormal cannabidiol was not different between WT and KO mice (WT 20+/-2%, KO 26+/-5% change from baseline), nor was the vasodilator response to abnormal cannabidiol in isolated mesenteric arteries (IC50 approximately 3 micro M for WT and KO). The abnormal cannabidiol vasodilator response was antagonized equivalently by O-1918 in both strains.

CONCLUSIONS

These results demonstrate that while GPR55 is activated by atypical cannabinoids, it does not appear to mediate the vasodilator effects of these agents.

An odyssey of islet transplantation for therapy of type 1 diabetes

Canadian surgical contributions to the field of islet transplantation have a rich heritage and a promising future. In this article, some seminal Canadian contributions to this field are reviewed, including contributions at the basic research laboratory and translational applications to bedside therapy of type 1 diabetes.

Effect of exenatide on beta cell function after islet transplantation in type 1 diabetes

BACKGROUND

Islet transplantation can reduce or eliminate the need for insulin in patients with type 1 diabetes. Exenatide is a long acting analogue of Glucagon-like peptide-1 (GLP-1) that augments glucose induced insulin secretion, and may increase beta cell mass. We evaluated the effect of exenatide on insulin secretion after islet transplantation.

METHODS

Eleven C-peptide positive islet cell recipients with elevated glucose levels were treated with exenatide for three months. Response was assessed by insulin requirements, meal tolerance tests, and hyperglycemic glucose clamps.

RESULTS

Ten patients responded to exenatide. Two patients who had not restarted insulin achieved good glycemic control and one patient who had received 5500 IE/kg in first islet infusion was able to stop insulin. Seven other patients decreased their insulin dose by 39% on exenatide. Hyperglycemic clamp studies showed a rise in second phase insulin release (before exenatide: 246+/-88 pM; during exenatide: 644+/-294 pM, P<0.01). Meal tolerance studies before and one month after stopping exenatide did not show a difference in glucose or C-peptide values. Nausea and vomiting were the major side effects.

CONCLUSIONS

Exenatide stimulates insulin secretion in islet transplant recipients. It reduces insulin dose in some patients and may delay the need to resume insulin in others. We did not find any evidence of a trophic effect on islets.

Urotensin II and renal function in the rat

Urotensin II (UII) is a potent vasoactive hormone in mammals. However, despite its well-known effects on epithelial sodium transport in fish, little is known about its actions on the mammalian kidney. The aim of this study was to determine the effects of UII on renal function in the rat. Using standard clearance methods, the effects of rUII and the rat UII receptor (UT) antagonist, urantide, were studied. UII was measured in plasma and urine by radioimmunoassay. UII and UT were localized in the kidney by immunohistochemistry and mRNA expression quantified. Rat urinary [UII] was 1,650-fold higher than that in plasma. Immunoreactive-UII was localized to the proximal tubules, outer and inner medullary collecting ducts (IMCD); UT receptor was identified in glomerular arterioles, thin ascending limbs, and IMCD. UII and UT mRNA expression was greater in the medulla; expression was higher still in spontaneously hypertensive rats (SHRs) associated with raised plasma (UII). Injection of rUII induced reductions in glomerular filtration rate (GFR), urine flow, and sodium excretion. Urantide infusion resulted in increases in these variables. Endogenous UII appears to contribute to the regulation of GFR and renal sodium and water handling in the rat. While hemodynamic changes predominate, we cannot rule out the possibility of a direct tubular action of UII. Increased expression of UII and UT in the SHR suggests that UII plays a role in the pathophysiology of cardiovascular disease.

Suppression of human T-cell responses to beta-cells by activation of B7-H4 pathway

B7-H4, a recently described member of the B7 family of cosignal molecules, is thought to be involved in the regulation of cellular and humoral immune responses through receptors on activated T and B cells. Human islet cells express positive B7-H4 mRNA in RT-PCR assays, but not B7-H4 protein on cell surface in flow cytometric analyses. To investigate the regulatory effects of activation of the B7-H4 pathway on the function of activated T cells of patients with type 1 diabetes (T1D), we have used our in vitro human experimental system, including human beta-cell antigen-specific T-cell clones and human beta-cell lines CM and HP62, as well as primary islet cells. B7-H4.Ig protein was purified from the culture supernatant of 293T cells transfected by a B7-H4.Ig plasmid (pMIgV, containing a human B7-H4 cDNA and a mouse IgG2a Fc cDNA). Our preliminary studies showed that immobilized fusion protein human B7-H4.Ig (coated with 5 microg/ml for 2 h at 37 degrees C), but not control Ig, clearly inhibited the proliferation of activated CD4+ and CD8+ T cells of patients induced by anti-CD3 antibody in CFSE assays. B7-H4.Ig also arrested cell cycle progression of T cells in G0/G1 phase and induced T-cell apoptosis as measured by BrdU-7-AAD flow cytometric analysis. To determine the cytoprotective effects of B7-H4, we developed transfectants of human beta-cell lines CM and HP62 and islet cells transfected with the B7-H4.Ig plasmid, using empty vector transfectants as controls. The results demonstrate that cell-associated B7-H4.Ig expressed on human beta-cells clearly inhibits the cytotoxicity of the T-cell clones to targeted human beta-cells in 51Cr release cytotoxicity assays. Activation of the B7-H4 pathway may represent a novel immunotherapeutic approach to inhibit T-cell responses for the prevention of beta-cell destruction in T1D.

Improved human pancreatic islet isolation for a prospective cohort study of islet transplantation vs best medical therapy in type 1 diabetes mellitus

HYPOTHESIS

A local multiorgan donor pancreas procurement program can provide a source for optimized isolation of purified viable islets for transplantation into patients with type 1 diabetes mellitus receiving best medical therapy.

DESIGN

Prospective before-after cohort study.

SETTING

Tertiary referral center.

PATIENTS

Glycemic control was assessed in 10 patients with diabetes-induced renal dysfunction who were enrolled in a best medical therapy program and then crossed over to islet transplantation.

INTERVENTIONS

Thirty human pancreata were retrieved from local multiorgan donors and consecutively processed with intraductal collagenase perfusion, continuous digestion, and density gradient purification (group 1, n = 9) or similarly processed but impure tissue fractions cultured in vitro and then repurified to retrieve additional islets (group 2, n = 21). Islets were implanted by percutaneous portal embolization, providing more than 10 000 islet equivalents (IE) per kilogram of body weight (infusions from 1-3 donors per patient) under cover of antithymocyte globulin, sirolimus, or mycophenolate mofetil and tacrolimus.

MAIN OUTCOME MEASURES

Islet yields, purity, and cell viability (caspase 3, terminal deoxynucleotidyl transferase-mediated biotin-deoxyuridine 5-triphosphate nick-end labeling stain, and insulin secretion in vitro) were compared. In patients, monitored metabolic parameters were C-peptide secretion, insulin requirements, glycemic excursion, and hemoglobin A(1c) (HbA(1c)).

RESULTS

For group 1 vs group 2, no differences were observed in pancreas age (43 vs 44 years), cold storage (5 vs 4 hours), or weight (73 vs 82 g). Group 2 yielded 453 690 IE vs 214 109 IE in group 1 (P = .002). Grafts contained 50% or more endocrine cells in both groups. No difference occurred in cell viability or insulin secretion. Islets from 90% of group 2 pancreata met release criteria for transplantation. C-peptide secretion was detected in all recipients and persisted with a median follow-up to 12 months (range, 6-21 months) after full islet transplantation. Daily insulin dependence was reversed in all patients for at least 3 months. Five patients resumed small insulin doses. Compared with the best care program, all patients had improved metabolic stability. The mean +/- SE HbA(1c) level at entry into the study was 7.8% +/- 0.5%, and this decreased to 6.9% +/- 0.2% after best care (P = .38) and further to 6.2% +/- 0.2% at 6 months after transplantation (P = .002 vs entry; P = .15 vs best care; analysis of variance).

CONCLUSIONS

Local pancreas donor retrieval with islet isolation and culture conditioning enabled an offer of islets for transplantation for 90% of consecutively processed pancreata. Isolated islets secreted insulin during prolonged follow-up after implantation into patients, yielding metabolic control comparable with that achieved by best medical therapy.

Improved survival of microencapsulated islets during in vitro culture and enhanced metabolic function following transplantation

AIMS/HYPOTHESIS

The aim of this study was to determine whether a simple alginate capsule can prolong islet survival and function during long-term tissue culture. We also wanted to observe the ability of these encapsulated islets to restore glucose responsiveness to diabetic recipients, along with the quantity of islets required to do so.

METHODS

We compared the recovery and metabolic function of encapsulated canine islets with that of non-encapsulated canine islets following 1, 2 or 3 weeks of tissue culture. These culture preparations were also transplanted into diabetic nude mice and compared for their ability to reverse diabetes. Furthermore, short-term cultured encapsulated and non-encapsulated islets were transplanted in varying numbers to determine the minimum dose required to normalise blood glucose and prolong recipient survival.

RESULTS

Islet recovery following 1, 2 and 3 weeks of tissue culture was significantly higher when islets were encapsulated. When these islets were recovered at 1, 2 and 3 weeks and transplanted into diabetic nude mice, survival at 100 days was 100% for all encapsulated groups, versus 66%, 33% and 33% respectively for the non-encapsulated islets. Additionally, substantially fewer short-term cultured islets were required to normalise blood glucose when the islets were encapsulated. Recipients of encapsulated islets also had significantly longer survival times than recipients of non-encapsulated preparations.

CONCLUSIONS/INTERPRETATION

This study demonstrates that encapsulation of islets with purified alginate improves islet survival and function in vitro and in vivo.