A local glucagon-like peptide 1 (GLP-1) system in human pancreatic islets

AIMS/HYPOTHESIS

Glucagon-like peptide 1 (GLP-1) is a major incretin, mainly produced by the intestinal L cells, with beneficial actions on pancreatic beta cells. However, while in vivo only very small amounts of GLP-1 reach the pancreas in bioactive form, some observations indicate that GLP-1 may also be produced in the islets. We performed comprehensive morphological, functional and molecular studies to evaluate the presence and various features of a local GLP-1 system in human pancreatic islet cells, including those from type 2 diabetic patients.

METHODS

The presence of insulin, glucagon, GLP-1, proconvertase (PC) 1/3 and PC2 was determined in human pancreas by immunohistochemistry with confocal microscopy. Islets were isolated from non-diabetic and type 2 diabetic donors. GLP-1 protein abundance was evaluated by immunoblotting and matrix-assisted laser desorption-ionisation-time of flight (MALDI-TOF) mass spectrometry. Single alpha and beta cell suspensions were obtained by enzymatic dissociation and FACS sorting. Glucagon and GLP-1 release were measured in response to nutrients.

RESULTS

Confocal microscopy showed the presence of GLP-1-like and PC1/3 immunoreactivity in subsets of alpha cells, whereas GLP-1 was not observed in beta cells. The presence of GLP-1 in isolated islets was confirmed by immunoblotting, followed by mass spectrometry. Isolated islets and alpha (but not beta) cell fractions released GLP-1, which was regulated by glucose and arginine. PC1/3 (also known as PCSK1) gene expression was shown in alpha cells. GLP-1 release was significantly higher from type 2 diabetic than from non-diabetic isolated islets.

CONCLUSIONS/INTERPRETATION

We have shown the presence of a functionally competent GLP-1 system in human pancreatic islets, which resides in alpha cells and might be modulated by type 2 diabetes.

Evidence for a role of frataxin in pancreatic islets isolated from multi-organ donors with and without type 2 diabetes mellitus

Frataxin (FXN) is a mitochondrial protein involved in iron metabolism and in the modulation of reactive oxygen and/or nitrogen species production. No information is currently available as for the role of frataxin in isolated human pancreatic islets. We studied islets from pancreases of multi-organ donors with (T2DM) and without (Ctrl) Type 2 diabetes mellitus. In these islets, we determined FXN gene and protein expression by qualitative and quantitative Real-Time RT-PCR, nitrotyrosine concentration, and insulin release in response to glucose stimulation (SI). FXN gene and protein were expressed in human islets, though the level of expression was much lower in T2DM islets. The latter also had lower insulin release and higher concentration of nitrotyrosine. A positive correlation was apparent between SI and FXN gene expression, while a negative correlation was found between nitrotyrosine islet concentration and FXN expression. Transfection of Ctrl islets with siRNA FXN caused reduction of FXN expression, increase of nitrotyrosine concentration, and reduction of insulin release. In conclusion, in human pancreatic islets FXN contributes to regulation of oxidative stress and insulin release in response to glucose. In islets from T2DM patients FXN expression is reduced while oxidative stress is increased and insulin release in response to glucose impaired.

Alcohol drinking after liver transplantation is associated with graft injury

AIM

This was a single-center, mixed-design, cross-sectional and retrospective study to assess the performance of the 4-item, self-reported CAGE (Cut down, Annoyed, Guilty, Eye-opener) questionnaire in predicting histology-proven alcohol-related liver graft injury (ARLGI).

METHODS

A total of 316 liver transplant (LT) patients between six months and five years were enrolled. Based on previous research, problem alcohol drinking (PAD) was defined as any score ≥ 1 on the CAGE, while a cut-off of 2 was assumed for alcohol dependence (AD).

RESULTS

Responders were 195, 45 (23.1%) had a CAGE score ≥ 1 and 30 (15.3%) scored ≥ 2. After controlling for confounders, PAD was associated with hyperlipidemia (P=0.01), while AD with a male gender (P=0.01), hyperlipidemia (P=0.03) and alcohol as native diagnosis (P=0.03). PAD and AD were both associated with a significantly higher prevalence of ARLGI, i.e. 53.3% and 63.3%, respectively (P<0.0001). Hepatitis C virus (HCV) patients with PAD showed more steatosis (P=0.04), portal infiltrate (P=0.03), and pericellular/perivenular fibrosis (P=0.02). The likelihood ratios for CAGE scores ranging from 0 to 4 in predicting ARLGI were 0, 5.2, 7.8, 7.8, and 100, respectively.

CONCLUSION

By use of a self-report instrument we found a 23.1% prevalence of PAD and a 15.3% prevalence of AD among LT patients between six months and five years. A variable degree of ARLGI was present in 53.3% of PAD and 63.3% of AD, respectively. HCV patients with PAD had more steatosis, portal inflammation, and pericellular fibrosis. Transplant physicians might improve their ability to predict the probability for ARLGI using the CAGE.

Patient satisfaction among liver transplant recipients: single-center survey

A single-center survey using a semistructured questionnaire was conducted in liver transplantation recipients at discharge after the primary surgery. The objectives of the study were to assess patient satisfaction and to identify critical points that negatively affected their perception of the quality of care received, and to derive information to enable improvement in current standards of care. The questionnaire included 5 sections about quality and 1 section for suggestions. Patients were asked to provide answers on a 5-item Likert scale. Areas assessed included quality of staff, organization, boarding, privacy, and transfer of care. Among 51 recipients, satisfaction was high (>50%) in all areas. Lower satisfaction scores were given for room services, diet, and background music. The most frequently reported area of dissatisfaction (12%) was lack of availability of in-hospital physical rehabilitation programs. Despite overall satisfaction with quality of care, recipients reported lack of appropriate physical rehabilitation programs in the early posttransplantation period.

Unintended transplantation of three organs from an HIV-positive donor: report of the analysis of an adverse event in a regional health care service in Italy

In February 2007, three organs from an human immunodeficiency virus (HIV)-positive donor were transplanted at two hospitals in the Tuscany Regional Health Care Service, owing to a chain of errors during the donation process. The heart-beating donor was a 41-year-old woman who died as a result of head trauma. The patient's history did not highlight any risky behavior. The available data on previous hospital admissions reported a negative result on HIV testing. During the donation process, the result of the lab test performed for evaluation of organ suitability was mistakenly transcribed from positive to negative. This wrong negative result was then included in the donation record without any cross-check. Therefore, the Regional Transplant Center allocated the liver and both kidneys. The patient also donated tissues, and a second laboratory conducted an evaluation of suitability for the tissue banks. During this process, only 5 days after the successful transplantation procedures, the positive HIV result was fed back to the Regional Transplant Center and the previous error discovered. Transplanted patients were immediately assessed and then treated with antiretroviral medications. A national commission soon performed a systems analysis of the adverse event. Besides the active error committed during the manual transcription for the HIV lab test result, the commission also identified technological factors, such as the lack of integration between the lab machine, the laboratory information system (LIS), and the donor record, as well as organizational factors, such as the distribution to two different labs of the suitability evaluation for organs and tissues. Recommendations included: automatic transmission of lab test results from the lab machine to the LIS and to the donor record, centralization of lab tests for suitability evaluation of organs and tissues, a training program to develop a proactive quality and safety culture in the regional network of donation and transplantations.

A common polymorphism in the monocyte chemoattractant protein-1 (MCP-1) gene regulatory region influences MCP-1 expression and function of isolated human pancreatic islets

BACKGROUND AND AIMS

Islet transplantation is an attractive approach to treat type 1 diabetic patients. However, suboptimal islet engraftment still represents an unsolved problem. It has been shown that human islets release monocyte chemoattractant protein-1 (MCP-1), one of the most powerful macrophage chemokines, which may impair the fate of the transplant. The aim of this study was to evaluate the presence and role of MCP-1 in isolated human islets, including genotyping for a common polymorphism.

METHODS

Pancreatic islets were isolated by enzymatic digestion and gradient purification from 41 nondiabetic multiorgan donors. We measured MCP-1 mRNA expression by quantitative real- time reverse-transcriptase polymerization chain reaction, analyzed the MCP-1 single nucleotide polymorphism, -2518 G/A (SNP, rs 1024611) and evaluated glucose-stimulated insulin release (IR; microU/islet/min).

RESULTS

MCP-1 mRNA expression was found in all studied batches of islets. Overall, IR was significantly higher at 16.7 mmol/L than 3.3 mmol/L glucose. We observed a significant negative correlation between MCP-1 mRNA expression and stimulation index (SI). We found that MCP-1 mRNA expression was significantly higher in CC and CT compared with TT genotype groups. Finally, SI was significant lower in the CC with respect to the TT genotype group.

CONCLUSIONS

These data show that MCP-1 gene expression regulated by the -2518 G/A polymorphism, is correlated with glucose-stimulated insulin release. The study of MCP-1 expression and genotype on isolated islets before transplantation may be useful to understand the inflammatory response after infusion of human islets into patients with type 1 diabetes mellitus.

Efficiency of the tissue procurement process: what evaluation tools?

Evaluation of the efficiency of tissue procurement (TP) requires appropriate indicators. We report the results of a survey on all in-hospital deaths in Tuscany performed to identify potential indicators of efficiency with regard to donor identification and evaluation. In January 2004, we established a regional, compulsory, prospective program to monitor all in-hospital deaths in Tuscany. Currently, in Tuscany TP is performed if donors are < or =75 years without evidence of infectious or malignant diseases. Between January 2004 and December 2008, we analyzed data on 75,921 in-hospital deaths, including 50,001 (66.9%) in subjects older than 75 years, while 25,920 (33.1%) were < or =75 years and thus considered for TP. Among the latter cohort, 11,657 (15.3%) presented with clinical contraindication(s), while 14,263 (18.8%) were fit for tissue donation. Of the latter population, tissue donation occurred in 3083 cases (ie, 4% of in-hospital deaths or 11.8% of potential tissue donors). Contraindications to tissue donation were identified in 9861 cases (12.9%) based on clinical files, and in 1796 (2.4%) after interview with the family. There was a great variability by regional hospital in the percent of contraindications identified after the family interview, from a low of 4% to a high of 45%. Based on our experience, implementation of efficiency parameters and improvement of the efficiency of the entire TP process requires compulsory reporting of in-hospital deaths by local transplant coordinators.

G-protein-coupled receptor 40 (GPR40) expression and its regulation in human pancreatic islets: the role of type 2 diabetes and fatty acids

BACKGROUND AND AIMS

GPR40 is a membrane-bound receptor paired with medium and long-chain fatty acids (FFA) as endogenous ligands. Its acute activation potentiates insulin secretion from beta cells, whereas prolonged binding might contribute to the deleterious effects of chronic exposure to FFA. Little information is available on the expression of GPR40 and its regulation in human islets (HI).

MATERIAL AND METHODS

HI were prepared by enzymatic digestion and gradient separation from the pancreas of 20 non-diabetic (Ctrl) and 13 type 2 diabetic (T2DM) multiorgan donors, and functional and molecular studies were then performed.

RESULTS

By qualitative and quantitative PCR experiments, mRNA expression was shown in HI. Both in T2DM islets and in Ctrl islets pre-exposed for 24 h to 1.0 mmol/l FFA (palmitate:oleate, 2:1), GPR40 mRNA expression was significantly reduced (p<0.01) in the T2DM cells as compared to Ctrl cells. A significant positive correlation was found between glucose-stimulated insulin secretion and GPR40 expression.

CONCLUSIONS

These results show the expression of GPR40 in human pancreatic islets which are regulated by FFA. The finding that T2DM islets have a lower GPR40 expression, and the correlation of these genes with insulin secretion, raises the possibility of an involvement of GPR40 in human diabetes beta-cell dysfunction.

Autophagy in human type 2 diabetes pancreatic beta cells

AIMS/HYPOTHESIS

Beta cell loss contributes to type 2 diabetes, with increased apoptosis representing an underlying mechanism. Autophagy, i.e. the physiological degradation of damaged organelles and proteins, may, if altered, be associated with a distinct form of cell death. We studied several features of autophagy in beta cells from type 2 diabetic patients and assessed the role of metabolic perturbation and pharmacological intervention.

METHODS

Pancreatic samples were obtained from organ donors and isolated islets prepared both by collagenase digestion and density gradient centrifugation. Beta cell morphology and morphometry were studied by electron microscopy. Gene expression studies were performed by quantitative RT-PCR.

RESULTS

Using electron microscopy, we observed more dead beta cells in diabetic (2.24 +/- 0.53%) than control (0.66 +/- 0.52%) samples (p < 0.01). Massive vacuole overload (suggesting altered autophagy) was associated with 1.18 +/- 0.54% dead beta cells in type 2 diabetic samples and with 0.36 +/- 0.26% in control samples (p < 0.05). Density volume of autophagic vacuoles and autophagosomes was significantly higher in diabetic beta cells. Unchanged gene expression of beclin-1 and ATG1 (also known as ULK1), and reduced transcription of LAMP2 and cathepsin B and D was observed in type 2 diabetic islets. Exposure of non-diabetic islets to increased NEFA concentration led to a marked increase of vacuole accumulation, together with enhanced beta cell death, which was associated with decreased LAMP2 expression. Metformin ameliorated autophagy alterations in diabetic beta cells and beta cells exposed to NEFA, a process associated with normalisation of LAMP2 expression.

CONCLUSIONS/INTERPRETATION

Beta cells in human type 2 diabetes have signs of altered autophagy, which may contribute to loss of beta cell mass. To preserve beta cell mass in diabetic patients, it may be necessary to target multiple cell-death pathways.

Interregional allocation models for liver transplantation

In light of the persistent donor scarcity, it has been advocated to shift the current region-based allocation model for liver transplantation (OLT) to an interregional one, so as to allow sicker patients on the wait list to obtain timely transplantations. Being convinced that tackling the challenge of organ donor scarcity requires appropriate measures, we have suggested some initiatives to be taken at different levels. First, definition of the real need for OLT, since it is largely unknown to transplant physicians and still represents the starting line for any initiative in the field. Second, we recommend creation of liver transplant care processes organized around the concept of smooth, seamless, and prompt referral of liver disease patients. Third, we suggest continued efforts in the field of deceased donation, so as to reduce the chasm between organ donation and demand and limit the persistent variability among regions. Fourth, we favor patient mobility, so as to expand the opportunity for transplantation for sicker patients. Finally, we seek to improve the efficiency of interregional coordination by prompt referral of extended criteria donors, sicker patients, or patients with rare diseases, so as to expand the opportunity for better donor-to-recipient matching at a national level.

A phase II (PhII) trial of sorafenib (S) in combination with 5-fluorouracil (5FU) continuous infusion (c.i.) in patients (pts) with advanced hepatocellular carcinoma (HCC): Preliminary data

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Background: S, an oral multi-kinase inhibitor that targets Raf-kinase and receptor tyrosine kinases, improved overall survival (OS) and time to progression (TTP) versus placebo in a randomized phase III study in HCC (SHARP study). The safety of S in association with infusional and bolus 5FU regimens was established in a previous PhI study, with no clinically relevant pharmacokinetic interaction between S and 5FU. The present trial was designed to evaluate the safety and efficacy of S with infusional 5FU in HCC pts. Methods: Patients with advanced HCC (not eligible to surgical or locoregional therapies), age≥18 years, Child-Pugh Class A or B, ECOG PS 0–1, without prior systemic treatment for HCC and adequate bone marrow, liver and renal function, were eligible for the study. The primary endpoint is the Disease Control Rate (DCR). Secondary endpoints included response rate, TTP, OS and safety. According to a two-step Simon's model 46 pts were to be accrued. Pts were treated with oral S 400 mg bid continuously and c.i. 5FU 200 mg/sqm/day day 1–14 every 3 weeks. Tumour response was assessed according to RECIST criteria every 9 weeks. Results: Between October 2006 and October 2008 38 pts were enrolled: M-F: 32–6, median age (range): 68(47–83) years, ECOG-PS 0–1: 28–10, Child-Pugh A-B: 35–3, extrahepatic spread: 14 pts, macroscopic vascular invasion: 6 pts. Grade 3/4 (%) toxicities (NCI CTC v 3.0 criteria) included diarrhoea 5/0, stomatitis 21/3, hand foot syndrome 21/0, skin rash 11/0, hypertension 11/0; hyperbilirubinemia 5/3, AST 11/0, ALT 8/0, cardiac toxicity (one cardiac failure, one atrial fibrillation) 5/0 and bleeding (melena) in 3/0. One partial response was observed. Stable disease was obtained in 45% of pts with a median duration of 9.6 months (range 5–18+). Median TTP was 7.6 months (CI 95%=5.3–9.9) and median OS 12.2 months (CI 95%=4.45–19.8). Conclusions: Preliminary results of this PhII study show encouraging disease control rate, TTP and OS in pts with advanced HCC. The S+5FU association is feasible, well tolerated and AEs were predictable and manageable.

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Transcranial doppler sonography is useful for the decision-making at the point of care in patients with acute hepatic failure: a single centre's experience

Acute hepatic failure (ALF) is an uncommon disease characterized by a rapid deterioration of the hepatic function with severe derangements of the mental status in previously healthy subjects due to massive hepatocytes necrosis. Neurological impairment, due to intracranial hypertension and cerebral ischemia, is a key factor because it is a main criterion to decide when to proceed to liver transplantation, which is only treatment for these patients. Therefore, neurological monitoring holds an essential role in the clinical management of ALF patients but it needs to be performed at the point-of-care in the majority of the cases as such critically ill patients cannot be moved away from the ICU because they frequently need continuous hemodynamic, ventilatory and renal support. We herein report and discuss our experience relating to the use of transcranial sonography as a neuro-monitoring tool in ALF patients. In our series this technique allowed a repeatable and reliable non-invasive assessment of cerebral blood flow changes at the bedside thus avoiding the complications associated with the use of an intracranial probe to measure intra-cranial pressure and making it possible to correctly evaluate the timing and feasibility of liver transplantation.

Tissue procurement and transplantation: a Tuscany perspective

Tissue procurement and transplantation are rarely taken into account as indicators of the efficiency of a regional donor procurement network. We present herein a retrospective review on Tuscany tissue procurement activities from 2004 until 2006. In 2003 the Tuscan Regional Government appointed a transplantation service authority to reorganize all regional donation and transplantation activities: the Organizzazione Toscana Trapianti (OTT). The regional tissue procurement network was based on either brain death (BD) and cardiac death (CD) donors under the responsibility of in-hospital transplantation coordinators (IHTCs). From 2004 to 2006, a total of 397 tissue donors were procured in Tuscany, and 4151 tissue transplantations were performed: 2909 skin grafts, 1209 bone grafts, and 33 heart valves. Over the same period, a total of 2116 cornea donors were procured; 4117 corneas were retrieved; 1779 were fit for transplantation, and 1418 were transplanted. Based on our experience, implementation of tissue procurement requires use of BD donors and paramount organizational efforts from IHTCs.

Effects of exendin-4 on islets from type 2 diabetes patients

Exendin-4 is a dipeptidyl peptidase IV (DPP-IV)-resistant glucagon-like peptide 1 (GLP-1) mimetic and its synthetic counterpart, exenatide, is being used in the therapy of type 2 diabetes (T2DM). No information, however, is currently available as for the direct action of exendin-4 on human T2DM islets. In the present study, we exposed pancreatic islets prepared from non-diabetic and T2DM subjects to exendin-4 for 48 h and found that the compound had several, direct beneficial actions on insulin secretion and the expression of genes involved in beta-cell function and differentiation.