Hyperglycemia impairs EAAT2 glutamate transporter trafficking and glutamate clearance in islets of Langerhans: implications for type 2 diabetes pathogenesis

Pancreatic endocrine cells employ a sophisticated system of paracrine and autocrine signals to synchronize their activities, including glutamate which controls hormone release and β-cell viability by acting on glutamate receptors expressed by endocrine cells. We here investigate whether alteration of the Excitatory Amino Acid Transporter 2 (EAAT2), the major glutamate clearance system in the islet, may occur in type 2 diabetes mellitus (T2DM) and contribute to β-cell dysfunction. Increased EAAT2 intracellular localization was evident in islets of Langerhans from T2DM subjects as compared with healthy control subjects, despite similar expression levels. Chronic treatment of islets from healthy donors with high glucose concentrations led to the transporter internalization in vesicular compartments and reduced [H3]-D-glutamate uptake (65±5% inhibition), phenocopying the findings in T2DM pancreatic sections. The transporter relocalization was associated to decreased Akt phosphorylation protein levels, suggesting an involvement of the PI3K/Akt pathway in the process. In line with this, PI3K inhibition by 100 µM LY294002 treatment in human and clonal β-cells, caused the transporter relocalization in intracellular compartments and significantly reduced the glutamate uptake compared to control conditions, suggesting that hyperglycemia changes the trafficking of the transporter to the plasma membrane. Upregulation of the glutamate transporter upon treatment with the antibiotic ceftriaxone rescued hyperglycemia-induced β-cells dysfunction and death. Our data underscore the significance of EAAT2 in regulating islet physiology and provide a rationale for potential therapeutic targeting of this transporter to preserve β-cell survival and function in diabetes.

Prevalence of gestational diabetes mellitus risk factors in singleton pregnancies obtained by assisted reproductive technology: An observational, retrospective, real-world study from a pregnancy registry

AIMS

Several studies showed that Assisted Reproductive Technology (ART) could affect gestational diabetes mellitus (GDM) onset. The aim of this study was to estimate the prevalence of GDM risk factors in a cohort of women with singleton pregnancy obtained by ART and complicated by GDM. Maternal and neonatal outcomes were explored.

METHODS

We retrospectively collected data of pregnancies of women with singleton pregnancy obtained by ART and complicated by GDM consecutively cared for at a specialized center for diabetes and pregnancy care. Prevalence and combination of GDM risk factors, their combinations and maternal-fetal outcomes were estimated.

RESULTS

Overall, our cohort included 50 women (mean age of 40.4 ± 4.7 years, mean pre-pregnancy BMI 26.3 ± 6.2 kg/m2). The most frequent GDM traditional risk factors were age ≥ 35 years (94 %), family history of diabetes (44 %), overweight (29 %) and obesity (19 %). Combining risk factors, 5 groups were identified with 1, 2, 3, 4, or 5 risk factors with a prevalence respectively of 28 %, 46 %, 20 %, 4 %, and 2 %. Examining features of the above groups, pre-pregnancy weight (p < 0.0001) and pre-pregnancy BMI (p < 0.0001) statistically significant differed in the 5 groups, increasing with higher numbers of risk factors. Regarding neonatal outcomes only neonatal hypoglycemia (p = 0.03) differed significantly among the groups, with higher percentages in women with higher numbers of combined risk factors.

CONCLUSION

Prevalence of GDM traditional risk factors in singleton ART pregnancies complicated by GDM is considerable. Such pregnancies need appropriate clinical attention because of the risk of adverse outcomes.

The Effectiveness of Superbolus on Postprandial Blood Glucose Management of Pregnant Women With Type 1 Diabetes

AIM

Pregnancies of women with pregestational diabetes are at risk of after-meal glucose peaks and late after-meal hypoglycemia, particularly at breakfast. We aimed to explore the effectiveness of a specific feature of insulin pump therapy called superbolus in preventing these glucose swings.

METHODS

In this retrospective observational study, we analyzed continuous glucose monitoring data of patients with type 1 diabetes in pregnancy who were advised to use superbolus to manage their breakfast. Some of the postprandial basal insulin delivery was partially reduced and delivered instead as additional insulin bolus on top of a normal bolus. Outcomes of interest were one hour after breakfast glucose levels, the time in glucose range for after breakfast period, the number of late hypoglycemic episodes.

RESULTS

Overall, 21 consecutive pregnant women with type 1 diabetes (mean age 34.3 ± 5.5 years, mean pregestational body mass index 23.7 ± 4.7 kg/m2, HbA1c levels during pregnancy 6.1 ± 0.6%) were studied. Superbolus reduced after breakfast glucose peaks (one hour after breakfast glucose levels 130 ± 17 mg/dL vs 123 ± 10 mg/dL before and after superbolus use, respectively, P = .01), improved the time in glucose range for after breakfast period (70.4% vs 50.8%, P = .001), and reduced the number of late hypoglycemic episodes (3 [1-5] vs 1 [0-2], P< .0001).

CONCLUSION

Superbolus was effective in avoiding after-meal glucose peaks, increased postprandial glucose time in target, without late hypoglycemia occurrence. It represents a valid option for the treatment of pregnant women with type 1 diabetes using insulin pump.

Effectiveness and Safety of the Intermittently Scanned Continuous Glucose Monitoring System FreeStyle Libre 2 in Patients with Type 2 Diabetes Treated with Basal Insulin or Oral Antidiabetic Drugs: An Observational, Retrospective Real-World Study

Intermittently Scanned Continuous Glucose Monitoring (isCGM) devices are increasingly being used in patients with type 2 diabetes mellitus (T2DM) on insulin therapy for their benefits regarding disease management. Evidence of isCGM use in patients with T2DM on basal or non-insulin therapy is lacking. This study aimed at assessing the efficacy and safety of isCGM in this population. This was an observational, retrospective, real-world study enrolling patients with T2DM who were starting the use of isCGM. Data from medical records (i.e., demographics, clinical characteristics, laboratory assessments, and isCGM metrics) were collected over three time periods (baseline, 3 and 6 months). The endpoints were glycated haemoglobin (HbA1c) changes and changes in isCGM metrics as defined by the International Consensus from baseline to 3 months and 6 months. Overall, 132 patients were included (69.5% male; mean age 68.2 ± 11.0 years; mean disease duration 19.0 ± 9.4 years; 79.7% on basal insulin ±non-insulin therapy; mean baseline HbA1c 8.1% ± 1.3%). The estimated mean change in HbA1c was statistically significant at three (-0.4 ± 1.0%; p = 0.003) and six months (-0.6 ± 1.3%; p < 0.0001). In conclusion, isCGM proved to be effective and safe in improving glycaemic control in patients with T2DM on basal insulin or non-insulin therapy.

Combined Inositols, α-Lactalbumin, Gymnema Sylvestre and Zinc Improve the Lipid Metabolic Profile of Patients with Type 2 Diabetes Mellitus: A Randomized Clinical Trial

Type 2 diabetes mellitus (T2DM) is characterized by high blood glucose levels and lipid alterations. Besides pharmacological treatment, lifestyle modifications and nutraceuticals can be used to manage glucose and lipid profiles, which is crucial for preventing, or avoiding, serious consequences associated with the condition. This randomized controlled clinical trial on 75 patients with T2DM evaluated the effects of a combination of myo-inositol and d-chiro-inositol (40:1), α-lactalbumin, Gymnema sylvestre, and zinc on glucose and lipid profile. The intention-to-treat analysis displayed no significant differences in glucose parameters between the groups; however, the study group displayed reduced levels of total cholesterol (p = 0.01) and LDL (p = 0.03) after 3 months of supplementation. A subgroup analysis involving patients who did not modify their antidiabetic therapy, after 6 months displayed improved levels of total cholesterol (p = 0.03) and LDL (p = 0.04) in the study group versus placebo, along with a greater body weight reduction (p = 0.03) after 3 months. Furthermore, within the study group, levels of HDL (p = 0.03) and triglycerides (p = 0.04) improved after 3 months. These findings support supplementation with myo-inositol and d-chiro-inositol (40:1), α-lactalbumin, Gymnema sylvestre, and zinc as an adjuvant and safe strategy to manage the lipid profiles of patients with T2DM.

Association of Sodium-Glucose Cotransporter 2 Inhibitors with Osteomyelitis and Other Lower Limb Safety Outcomes in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Our aim was to evaluate osteomyelitis and other major lower limb safety outcomes (i.e., peripheral artery disease or PAD, ulcers, atraumatic fractures, amputations, symmetric polyneuropathy, and infections) in patients affected by type 2 diabetes mellitus (T2DM) and treated with sodium-glucose cotransporter 2 inhibitors (SGLT2-is). We thus performed a systematic review and meta-analysis of randomised controlled trials (RCTs) comparing SGLT2-is at approved doses for T2DM with a placebo or standard of care. MEDLINE, Embase, and Cochrane CENTRAL were searched through August 2022. Separate intention-to-treat analyses were implemented for each molecule to calculate Mantel-Haenszel risk ratios (RR_MH) with 95% confidence intervals (CIs) through a random-effects model. We processed data from 42 RCTs for a total of 29,491 and 23,052 patients, respectively assigned to SGLT2-i and comparator groups. SGLT2-is showed a pooled neutral effect on osteomyelitis, PAD, fractures, and symmetric polyneuropathy, whereas slightly deleterious sway on ulcers (RR_MH 1.39 [1.01-1.91]), amputations (RR_MH 1.27 [1.04-1.55]), and infections (RR_MH 1.20 [1.02-1.40]). In conclusion, SGLT2-is appear to not significantly interfere with the onset of osteomyelitis, PAD, lower limb fractures, or symmetric polyneuropathy, even though the number of these events proved consistently higher in the investigational groups; otherwise, local ulcers, amputations, and overall infections may be favoured by their employment. This study is registered with the Open Science Framework (OSF).

Long-term cultures of human pancreatic islets in self-assembling peptides hydrogels

Human pancreatic islets transplantation is an experimental therapeutic treatment for Type I Diabetes. Limited islets lifespan in culture remains the main drawback, due to the absence of native extracellular matrix as mechanical support after their enzymatic and mechanical isolation procedure. Extending the limited islets lifespan by creating a long-term in vitro culture remains a challenge. In this study, three biomimetic self-assembling peptides were proposed as potential candidates to recreate in vitro a pancreatic extracellular matrix, with the aim to mechanically and biologically support human pancreatic islets, by creating a three-dimensional culture system. The embedded human islets were analyzed for morphology and functionality in long-term cultures (14-and 28-days), by evaluating β-cells content, endocrine component, and extracellular matrix constituents. The three-dimensional support provided by HYDROSAP scaffold, and cultured into MIAMI medium, displayed a preserved islets functionality, a maintained rounded islets morphology and an invariable islets diameter up to 4 weeks, with results analogues to freshly-isolated islets. In vivo efficacy studies of the in vitro 3D cell culture system are ongoing; however, preliminary data suggest that human pancreatic islets pre-cultured for 2 weeks in HYDROSAP hydrogels and transplanted under subrenal capsule may restore normoglycemia in diabetic mice. Therefore, engineered self-assembling peptide scaffolds may provide a useful platform for long-term maintenance and preservation of functional human pancreatic islets in vitro.

Vitamin D Supplementation Impacts Systemic Biomarkers of Collagen Degradation and Copper Metabolism in Patients With Keratoconus

Purpose

To evaluate the impact of vitamin D (Vit D) supplementation on systemic biomarkers of collagen degradation, inflammation, oxidative stress, and copper metabolism in adolescent patients with keratoconus (KC).

Methods

This was a prospective observational pilot study. Twenty patients (age range, 16-19 years) presenting KC and Vit D insufficiency (<30 ng/mL) were included. Vit D supplementation was prescribed by their general practitioner as per the standard of care. Patients were followed up for 12 months. At each visit, best spectacle-corrected visual acuity (BSCVA), maximal keratometry (Kmax), and thinnest corneal thickness (TCT) were evaluated. The primary outcome of the study was the proportion of patients with Kmax progression of less than 1 D throughout the 12-month follow-up time. Blood samples were collected at different time points to evaluate Vit D levels and systemic markers of collagen degradation, inflammation, oxidative stress, and copper metabolism by ELISA or RT-PCR.

Results

Lower Vit D levels in the plasma were correlated with higher levels of systemic biomarkers of collagen degradation. Vit D supplementation increased the cell availability of copper. Moreover, stabilization of KC progression was found in 60% of patients (72% of eyes) after 12 months with Vit D supplementation. BSCVA, Kmax, and TCT rates remained stable during the observation period.

Conclusions

Our findings support that Vit D administration could affect ocular and systemic biomarkers in KC and illuminate a possible mechanism that can be used to develop new treatment alternatives.

Translational Relevance

Although KC therapy currently relies exclusively on surgical procedures, Vit D supplementation may offer a non-invasive and inexpensive alternative with minimal associated side effects.

SGLT2-inhibitors are effective and safe in the elderly: The SOLD study

BACKGROUND AND AIMS

Sodium-glucose co-transporter-2 inhibitors (SGLT2i) may have important benefits for the elderly with type 2 diabetes (T2D), however some safety concerns still limit their use in patients over 70 years of age. The SOLD study (SGLT2i in Older Diabetic patients) is a multicenter study, aimed to evaluate the effectiveness and safety of SGLT2i in the older diabetic patients in a real-life setting.

MATERIALS AND METHODS

We analyzed a population of 739 adults (mean age 75.4 ± 3.9 years, M/F 420/319) with T2D, which started a SGLT2i-based treatment after the age of 70, with at least one year of follow-up. Data were collected at baseline, at 6 and 12 months of follow-up.

RESULTS

SGLT2i (37.5% Empagliflozin, 35.7% Dapagliflozin, 26.1% Canagliflozin, 0.7% Ertugliflozin) were an add-on therapy to Metformin in 88.6%, to basal insulin in 36.1% and to other antidiabetic drugs in 29.6% of cases. 565 subjects completed the follow up, while 174 (23.5%) discontinued treatment due to adverse events which were SGLT2i related. A statistically significant reduction of glycated hemoglobin (baseline vs 12 months: 7.8 ± 1.1 vs 7.1 ± 0.8%, p < 0.001) and body mass index values (baseline vs 12 months: 29.2 ± 4.7 vs 28.1 ± 4.5 kg/m2, p < 0.001) were evident during follow-up. Overall, estimated glomerular filtration rate remained stable over time, with significant reduction of urinary albumin excretion. In the subgroup of patients which were ≥ 80 years, a significant improvement in glycated hemoglobin values without renal function alterations was evident. Overall discontinuation rate during the follow-up period was different across age groups, being urinary tract infections and worsening of renal function the most common cause.

CONCLUSION

SGLT2i are well-tolerated and safe in the elderly and appear as an effective therapeutic option, though some caution is also suggested, especially in more fragile subjects.

Minimed Medtronic 780G optimizes glucose control in patients with type 1 diabetes mellitus

BACKGROUND AND AIMS

The new advanced hybrid closed loop insulin infusion systems have the potential to significantly improve glycaemic control. The aim of this study was to evaluate the effectiveness of the Minimed 780G system in 59 patients with type 1 diabetes.

METHODS AND RESULTS

Glucose control obtained by using the system in automatic mode at 1-2 months of activation, at 2-4 months, at 4-6 months, and beyond 6 month was compared with those obtained with the system in manual mode. A significant improvement in time-in-range and in time-above-range throughout the follow-up was observed, as well as a significant reduction in time-below-range (<54 mg/dl) after 6 months, a significant reduction of the glucose variability and of HbA1c. After switching the mode, all target percentages lied on the average within the recommended ranges by literature consensus and no severe hypoglycemia nor ketoacidosis episodes were recorded.

CONCLUSION

The Minimed 780G allowed a rapid and progressive improvement of the overall glucose control.

The effectiveness of a televisit service for people with type 1 diabetes: An observational, retrospective, single center, one year follow-up study

The use of a televisit service complying with efficiency and safety regulatory parameters was effective in significantly improving HbA1c levels of people with T1D after a one-year follow-up period. No acute diabetes-related complications occurred. Patients were highly satisfied with the service. Televisit is a valid option for diabetes management.

IOL Power Calculation in Eyes Undergoing Combined Descemet Membrane Endothelial Keratoplasty and Cataract Surgery

PURPOSE

To assess the accuracy of different corneal powers for intraocular (IOL) power calculation in combined Descemet membrane endothelial keratoplasty (DMEK) and cataract surgery and investigate whether preoperative parameters correlate to the prediction error (PE).

METHODS

This prospective case series involved patients with Fuchs endothelial dystrophy receiving combined DMEK and cataract surgery. Preoperatively, patients underwent optical biometry and anterior segment OCT (AS-OCT). AS-OCT measurements were repeated 6 months postoperatively, when final refraction was assessed. The PE was calculated using the preoperative average keratometry (K_ave) measured by the optical biometer and User Group for Laser Interference Biometry (ULIB) constants. It was also calculated, after constant optimization, using the preoperative K_ave from both devices and the total corneal power (TCP) measured by AS-OCT, as well as the postoperative K_ave and TCP measured by AS-OCT.

RESULTS

ULIB constants resulted in the highest hyperopic PE (P < .0001). Constant optimization improved the results, because the PE was zeroed out and the absolute PEs decreased. No significant difference was found among the Barrett Universal II, Emmetropia Verifying Optical 2.0, Haigis, Hoffer Q, Holladay 1, Kane, and SRK/T formulas. Further improvement was achieved with the postoperative K_ave and TCP, although the accuracy remained moderate. The PE based on preoperative corneal measurements was correlated to the amount of corneal flattening; the latter could be predicted by multiple linear regression accounting for anterior and posterior corneal radii (P = .0002) and was correlated to the preoperative anterior/posterior ratio.

CONCLUSIONS

Constant optimization is beneficial for combined DMEK and phacoemulsification. Predicting postoperative corneal flattening may improve the results of IOL power accuracy. [J Refract Surg. 2022;38(7):435-442.].

The IGFBP3/TMEM219 pathway regulates beta cell homeostasis

Loss of pancreatic beta cells is a central feature of type 1 (T1D) and type 2 (T2D) diabetes, but a therapeutic strategy to preserve beta cell mass remains to be established. Here we show that the death receptor TMEM219 is expressed on pancreatic beta cells and that signaling through its ligand insulin-like growth factor binding protein 3 (IGFBP3) leads to beta cell loss and dysfunction. Increased peripheral IGFBP3 was observed in established and at-risk T1D/T2D patients and was confirmed in T1D/T2D preclinical models, suggesting that dysfunctional IGFBP3/TMEM219 signaling is associated with abnormalities in beta cells homeostasis. In vitro and in vivo short-term IGFBP3/TMEM219 inhibition and TMEM219 genetic ablation preserved beta cells and prevented/delayed diabetes onset, while long-term IGFBP3/TMEM219 blockade allowed for beta cell expansion. Interestingly, in several patients' cohorts restoration of appropriate IGFBP3 levels was associated with improved beta cell function. The IGFBP3/TMEM219 pathway is thus shown to be a physiological regulator of beta cell homeostasis and is also demonstrated to be disrupted in T1D/T2D. IGFBP3/TMEM219 targeting may therefore serve as a therapeutic option in diabetes.

Advanced technology for type 1 diabetes care in a deaf-mute patient

A 48-year-old deaf-mute man attending our outpatient clinic for long-term severely decompensated type 1 diabetes (mean glycated haemoglobin over 100 mmol/mol) has proved to be the best candidate for the beneficial implant of a next-generation closed loop insulin pump featuring a new refined auto-correction algorithm. The patient had already worn a stand-alone real-time continuous glucose monitoring (rt-CGM) device for 2 years, but his haemoglobin A1c (HbA1c) remained out of target with ample glucose variability. Then, we decided to use a novel advanced hybrid closed-loop insulin pump (the MiniMed 780G) coupled with his CGM device. After only 4 months this system led to a significant improvement in mean daily glucose levels (201±100 mg/dL vs 141±57 mg/dL), time in glucose range (43% vs 78%), percentage of time spent in hyperglycaemia (52% vs 20%), glucose variability (Coefficient of Variation 46% vs 38%), and HbA1c levels (121 mmol/mol vs 56 mmol/mol). The patient was highly satisfied.

The role of inflammation and neurodegeneration in diabetic macular edema

The pathogenesis of diabetic macular edema (DME) is complex. Persistently high blood glucose activates multiple cellular pathways and induces inflammation, oxidation stress, and vascular dysfunction. Retinal ganglion cells, macroglial and microglial cells, endothelial cells, pericytes, and retinal pigment epithelium cells are involved. Neurodegeneration, characterized by dysfunction or apoptotic loss of retinal neurons, occurs early and independently from the vascular alterations. Despite the increasing knowledge on the pathways involved in DME, only limited therapeutic strategies are available. Besides antiangiogenic drugs and intravitreal corticosteroids, alternative therapeutic options tackling inflammation, oxidative stress, and neurodegeneration have been considered, but none of them has been currently approved.

Glycated Albumin for Glycemic Control in T2DM Population: A Multi-Dimensional Evaluation

Purpose

To investigate the glycated albumin (GA) introduction implications, as an add-on strategy to traditional glycemic control (Hb1Ac and fasting plasma glucose – FPG) instruments, considering insulin-naïve individuals with type 2 diabetes mellitus (T2DM), treated with oral therapies.

Methods

A Health Technology Assessment was conducted in Italy, as a multi-dimensional approach useful to validate any innovative technology. The HTA dimensions, derived from the EUnetHTA Core Model, were deployed by means of literature evidence, health economics tools and qualitative questionnaires, filled-in by 15 professionals.

Results

Literature stated that the GA introduction could lead to a higher number of individuals achieving therapeutic success after 3 months of therapy (97.0% vs 71.6% without GA). From an economic point of view, considering a projection of 1,955,447 T2DM insulin-naïve individuals, potentially treated with oral therapy, GA introduction would imply fewer individuals requiring a therapy switch (−89.44%), with a 1.06% in costs reduction, on annual basis, thus being also the preferable solution from a cost-effectiveness perspective (cost-effectiveness value: 237.74 vs 325.53). According to experts opinions, lower perceptions on GA emerged with regard to equity aspects (0.13 vs 0.72, p-value>0.05), whereas it would improve both individuals (2.17 vs 1.33, p-value=0.000) and caregivers quality of life (1.50 vs 0.83, p-value=0.000). Even if in the short term, GA required additional investments in training courses (−0.80 vs 0.10, p-value = 0.036), in the long run, GA could become the preferable technology (0.30 vs 0.01, p-value=0.018) from an organisational perspective.

Conclusion

Adding GA to traditional glycaemic control instruments could improve the clinical pathway of individuals with T2DM, leading to economic and organisational advantages for both hospitals and National Healthcare Systems.

NF-κB activity during pancreas development regulates adult β-cell mass by modulating neonatal β-cell proliferation and apoptosis

NF-κB is a well-characterized transcription factor, widely known for its roles in inflammation and immune responses, as well as in control of cell division and apoptosis. However, its function in β-cells is still being debated, as it appears to depend on the timing and kinetics of its activation. To elucidate the temporal role of NF-κB in vivo, we have generated two transgenic mouse models, the ToIβ and NOD/ToIβ mice, in which NF-κB activation is specifically and conditionally inhibited in β-cells. In this study, we present a novel function of the canonical NF-κB pathway during murine islet β-cell development. Interestingly, inhibiting the NF-κB pathway in β-cells during embryogenesis, but not after birth, in both ToIβ and NOD/ToIβ mice, increased β-cell turnover, ultimately resulting in a reduced β-cell mass. On the NOD background, this was associated with a marked increase in insulitis and diabetes incidence. While a robust nuclear immunoreactivity of the NF-κB p65-subunit was found in neonatal β-cells, significant activation was not detected in β-cells of either adult NOD/ToIβ mice or in the pancreata of recently diagnosed adult T1D patients. Moreover, in NOD/ToIβ mice, inhibiting NF-κB post-weaning had no effect on the development of diabetes or β-cell dysfunction. In conclusion, our data point to NF-κB as an important component of the physiological regulatory circuit that controls the balance of β-cell proliferation and apoptosis in the early developmental stages of insulin-producing cells, thus modulating β-cell mass and the development of diabetes in the mouse model of T1D.

Verbascoside Protects Pancreatic β-Cells against ER-Stress

Substantial epidemiological evidence indicates that a diet rich in polyphenols protects against developing type 2 diabetes. The phenylethanoid glycoside verbascoside/acteoside, a widespread polyphenolic plant compound, has several biological properties including strong antioxidant, anti-inflammatory and neuroprotective activities. The aim of this research was to test the possible effects of verbascoside on pancreatic β-cells, a target never tested before. Mouse and human β-cells were incubated with verbascoside (0.8-16 µM) for up to five days and a combination of biochemical and imaging techniques were used to assess the β-cell survival and function under normal or endoplasmic reticulum (ER)-stress inducing conditions. We found a dose-dependent protective effect of verbascoside against oxidative stress in clonal and human β-cells. Mechanistic studies revealed that the polyphenol protects β-cells against ER-stress mediated dysfunctions, modulating the activation of the protein kinase RNA-like endoplasmic reticulum kinase (PERK) branch of the unfolded protein response and promoting mitochondrial dynamics. As a result, increased viability, mitochondrial function and insulin content were detected in these cells. These studies provide the evidence that verbascoside boosts the ability of β-cells to cope with ER-stress, an important contributor of β-cell dysfunction and failure in diabetic conditions and support the therapeutic potential of verbascoside in diabetes.

Targeting CXCR1/2 Does Not Improve Insulin Secretion After Pancreatic Islet Transplantation: A Phase 3, Double-Blind, Randomized, Placebo-Controlled Trial in Type 1 Diabetes

OBJECTIVE

Reparixin is an inhibitor of CXCR1/2 chemokine receptor shown to be an effective anti-inflammatory adjuvant in a pilot clinical trial in allotransplant recipients.

RESEARCH DESIGN AND METHODS

A phase 3, multicenter, randomized, double-blind, parallel-assignment study (NCT01817959) was conducted in recipients of islet allotransplants randomized (2:1) to reparixin or placebo in addition to immunosuppression. Primary outcome was the area under the curve (AUC) for C-peptide during the mixed-meal tolerance test at day 75 ± 5 after the first and day 365 ± 14 after the last transplant. Secondary end points included insulin independence and standard measures of glycemic control.

RESULTS

The intention-to-treat analysis did not show a significant difference in C-peptide AUC at both day 75 (27 on reparixin vs. 18 on placebo, P = 0.99) and day 365 (24 on reparixin vs. 15 on placebo, P = 0.71). There was no statistically significant difference between treatment groups at any time point for any secondary variable. Analysis of patient subsets showed a trend for a higher percentage of subjects retaining insulin independence for 1 year after a single islet infusion in patients receiving reparixin as compared with patients receiving placebo (26.7% vs. 0%, P = 0.09) when antithymocyte globulin was used as induction immunosuppression.

CONCLUSIONS

In this first double-blind randomized trial, islet transplantation data obtained with reparixin do not support a role of CXCR1/2 inhibition in preventing islet inflammation-mediated damage.

From Prediabetes to Type 2 Diabetes Mellitus in Women with Polycystic Ovary Syndrome: Lifestyle and Pharmacological Management

AIMS

Despite the very clear association between polycystic ovary syndrome (PCOS) and dysglycemia, few studies have explored the continuum of glycemic alterations leading from minor glucose abnormalities to overt diabetes. The purpose of this review is to trace the natural history of glycemic alteration in women with PCOS.

METHODS

We performed a literature review without time limit until August 2019. Inclusion criteria were studies addressing the association between impaired glucose tolerance or impaired fasting glucose or type 2 diabetes (T2D) and PCOS with at least an English abstract. The exclusion criteria were no PCOS or impaired glucose tolerance or impaired fasting glucose or T2D as outcome. The outcomes of interest were the onset of impaired glucose tolerance, impaired fasting glucose, T2D, and the progression from impaired glucose tolerance or impaired fasting glucose to T2D.

RESULTS

Healthy diet and physical activity are the first-line therapy for PCOS. Treatment with metformin was associated with significant lower 2-hour postload glucose levels and with reduction in fasting glucose when compared to placebo. Thiazolidinediones were more effective in reducing fasting glucose levels compared to placebo. Metformin and pioglitazone treatments showed similar effects on fasting glucose levels. The sodium-glucose cotransporter-2 inhibitor empagliflozin did not show differences in metabolic parameters when compared to metformin. The combination therapy with metformin plus the glucagon-like peptide-1 receptor agonist liraglutide was associated with significant improvements in basal and postload glucose levels compared with only liraglutide. Likewise, a combination therapy with the dipeptidyl peptidase-4 inhibitor saxagliptin and metformin demonstrated superiority versus metformin in fasting glucose and oral glucose tolerance test normalization. Myo-inositol supplementation was associated with lower insulin levels, glucose levels, and insulin resistance when compared with placebo, metformin, or estrogen treatments.

CONCLUSIONS

The use of insulin-sensitizing agents, such as metformin and inositols, along with lifestyle interventions may improve the metabolic profile in PCOS women.

The Role of Vitamin D and Omega-3 PUFAs in Islet Transplantation

Recurrence of autoimmunity and allograft rejection represent major challenges that impact the success of islet transplantation. Despite the remarkable improvements achieved in immunosuppression strategies after the publication of the Edmonton protocol, long-term data of intra-hepatic islet transplantation show a gradual decline in beta-cell function. Therefore, there is a growing interest in the investigation of novel, safe and effective anti-inflammatory and immunomodulatory strategies able to promote long-term islet graft survival and notable improvements in clinical outcomes of islet transplant recipients. Vitamin D has been shown to exert anti-inflammatory and immunomodulatory effects. Pre-clinical studies investigating the use of vitamin D and its analogs (alone or in combination with immunosuppressive agents and/or other anti-inflammatory agents, such as omega-3 polyunsaturated fatty acids) showed beneficial results in terms of islet graft survival and prevention of recurrence of autoimmunity/allograft rejection in animal models of syngeneic and allogeneic islet transplantation. Moreover, epidemiologic studies demonstrated that vitamin D deficiency is highly prevalent after solid organ transplantation (e.g., heart, liver or kidney transplantation). However, studies that critically assess the prevalence of vitamin D deficiency among islet transplant recipients have yet to be conducted. In addition, prospective studies aimed to address the safety and efficacy of vitamin D supplementation as an adjuvant immunomodulatory strategy in islet transplant recipients are lacking and are therefore awaited in the future.

Intramuscular islet allotransplantation in type 1 diabetes mellitus

OBJECTIVE

Alternative sites to the liver for islet transplantation have been studied for a long time. Intramuscular islet transplantation appears to be an alternative site to the liver because of the ease of access. First islet autotransplantations were reported in patients after total pancreatectomies. The transplanted islets showed a proper revascularization and their function was observed for up to 2 years after the implant. However, only a few cases of autotransplantation and no allotransplantation have been performed. The aim of this study was to verify the feasibility of islet allotransplantation into muscles.

PATIENTS AND METHODS

In four patients affected by type 1 diabetes mellitus in which liver islet allotransplantation was contraindicated, human islets were transplanted into patients' arm muscle with local anesthesia.

RESULTS

The surgery was minimally invasive, without complications. In one patient a moderate local inflammatory reaction was observed at the site of the implant, which resolved spontaneously within 4 days. Islet graft function was observed after transplantation in all patients, but it progressively disappeared in 3 out 4 patients within a short time.

CONCLUSIONS

In this first ever-reported intramuscular pancreatic islet allotransplantation, the procedure appears feasible but new strategies must be envisaged to significantly improve islet engraftment and the long-term graft function.

The role of Cox-2 and prostaglandin E2 receptor EP3 in pancreatic β-cell death

Elevated levels of lipids, in particular saturated fatty acids, are known to be associated with type 2 diabetes (T2D) and to have a negative effect on β-cell function and survival. We bring new evidence indicating that palmitate up-regulates cyclooxygenase-2 (COX-2) expression levels in human islets and in MIN6 β cells, and that it is elevated in islets isolated from T2D donors. Both small interfering specific cyclooxygenase-2 small interfering RNA (siRNA) or the COX-2 inhibitor celecoxib significantly inhibited apoptosis induced by palmitate. Prostaglandin E₂ (PGE₂), the predominant product of COX-2 enzymatic activity, activates membrane receptors, which are members of the GPCR-family (EP1-EP4). In the present study, elevated expression of the PGE₂ receptor subtype 3 (EP3) receptor was observed in β cells exposed to palmitate and in islets from individuals with T2D. Down-regulation of the pathway using EP3 siRNA or the specific L-798,106 antagonist markedly decreased the levels of palmitate-induced apoptosis. Altogether, our data put forward the COX-2-PGE₂-EP3 pathway as one of the mediators of palmitate-induced apoptosis in β-cells.-Amior, L., Srivastava, R., Nano, R., Bertuzzi, F., Melloul, D. The role of Cox-2 and prostaglandin E₂ receptor EP3 in pancreatic β-cell death.

Islet transplantation in Italy

Two centers have now an active islet transplant program in Italy, both placed in Milan: the San Raffaele Scientific Institute and the Niguarda Hospital. Up to 2018 in Italy about 200 patients affected by type 1 diabetes mellitus received an islet allotransplantation and about 100 patients received an islet auto-transplantation after a partial or total pancreatectomy. In spite of this large volume of activities, there is not a specific reimbursement fee for islet isolation and current reimbursement based on the Diagnosis-related group covers only partially the hospitalization and the islet transplantation costs.

Pumps or Multiple Daily Injections in Pregnancy Involving Type 1 Diabetes: A Prespecified Analysis of the CONCEPTT Randomized Trial

OBJECTIVE

To compare glycemic control, quality of life, and pregnancy outcomes of women using insulin pumps and multiple daily injection therapy (MDI) during the Continuous Glucose Monitoring in Women With Type 1 Diabetes in Pregnancy Trial (CONCEPTT).

RESEARCH DESIGN AND METHODS

This was a prespecified analysis of CONCEPTT involving 248 pregnant women from 31 centers. Randomization was stratified for pump versus MDI and HbA_1c. The primary outcome was change in HbA_1c from randomization to 34 weeks' gestation. Key secondary outcomes were continuous glucose monitoring (CGM) measures, maternal-infant health, and patient-reported outcomes.

RESULTS

At baseline, pump users were more often in stable relationships (P = 0.003), more likely to take preconception vitamins (P = 0.03), and less likely to smoke (P = 0.02). Pump and MDI users had comparable first-trimester glycemia: HbA_1c 6.84 ± 0.71 vs. 6.95 ± 0.58% (51 ± 7.8 vs. 52 ± 6.3 mmol/mol) (P = 0.31) and CGM time in target (51 ± 14 vs. 50 ± 13%) (P = 0.40). At 34 weeks, MDI users had a greater decrease in HbA_1c (-0.55 ± 0.59 vs. -0.32 ± 0.65%, P = 0.001). At 24 and 34 weeks, MDI users were more likely to achieve target HbA_1c (P = 0.009 and P = 0.001, respectively). Pump users had more hypertensive disorders (P = 0.011), mainly driven by increased gestational hypertension (14.4 vs. 5.2%; P = 0.025), and more neonatal hypoglycemia (31.8 vs. 19.1%, P = 0.05) and neonatal intensive care unit (NICU) admissions >24 h (44.5 vs. 29.6%; P = 0.02). Pump users had a larger reduction in hypoglycemia-related anxiety (P = 0.05) but greater decline in health/well-being (P = 0.02).

CONCLUSIONS

In CONCEPTT, MDI users were more likely to have better glycemic outcomes and less likely to have gestational hypertension, neonatal hypoglycemia, and NICU admissions than pump users. These data suggest that implementation of insulin pump therapy is potentially suboptimal during pregnancy.

Islet-Derived eATP Fuels Autoreactive CD8+ T Cells and Facilitates the Onset of Type 1 Diabetes

Extracellular ATP (eATP) activates T cells by engaging the P2X7R receptor. We identified two loss-of-function P2X7R mutations that are protective against type 1 diabetes (T1D) and thus hypothesized that eATP/P2X7R signaling may represent an early step in T1D onset. Specifically, we observed that in patients with newly diagnosed T1D, P2X7R is upregulated on CD8⁺ effector T cells in comparison with healthy control subjects. eATP is released at high levels by human/murine islets in vitro in high-glucose/inflammatory conditions, thus upregulating P2X7R on CD8⁺ T cells in vitro. P2X7R blockade with oxidized ATP reduces the CD8⁺ T cell-mediated autoimmune response in vitro and delays diabetes onset in NOD mice. Autoreactive CD8⁺ T-cell activation is highly dependent upon eATP/P2X7R-mediated priming, while a novel sP2X7R recombinant protein abrogates changes in metabolism and the autoimmune response associated with CD8⁺ T cells. eATP/P2X7R signaling facilitates the onset of autoimmune T1D by fueling autoreactive CD8⁺ cells and therefore represents a novel targeted therapeutic for the disorder.

Long-term Effect of Islet Transplantation on Glycemic Variability

Islet transplantation has been reported to restore normoglycemia and the overall metabolic control in type 1 diabetes mellitus (DM). In the most experienced centers, islet transplantation clinical outcome is similar to that of the whole pancreas transplantation. Long-term islet transplantation function remains a very interesting matter worth discussing. A progressive islet function decrease was reported, probably due to islet exhaustion. In 5 islet-transplanted patients with at least 3-yr follow-up and still insulin independent, their glycemic control was characterized by a blinded retrospective continuous glucose monitoring system (CGMS). Islet transplantation restored glycemic control and glucose variability. Data were compared with patients in the waiting list. All the parameters of glycemic variability tested had improved significantly in patients who had islet transplantation compared with those patients who were on the waiting list. In conclusion, islet transplantation is able to maintain a proper glucose control and normalize glycemic variability in selected patients. A blinded retrospective CGMS is a useful method to characterize glucose homeostasis deeply in vivo in islet-transplanted patients.

Metabolic control and complications in Italian people with diabetes treated with continuous subcutaneous insulin infusion

BACKGROUND AND AIM

The objective of this cross-sectional study was to evaluate the degree of glycaemic control and the frequency of diabetic complications in Italian people with diabetes who were treated with continuous subcutaneous insulin infusion (CSII).

METHODS AND RESULTS

Questionnaires investigating the organisation of diabetes care centres, individuals' clinical and metabolic features and pump technology and its management were sent to adult and paediatric diabetes centres that use CSII for treatment in Italy. Information on standard clinical variables, demographic data and acute and chronic diabetic complications was derived from local clinical management systems. The sample consisted of 6623 people with diabetes, which was obtained from 93 centres. Of them, 98.8% had type 1 diabetes mellitus, 57.2% were female, 64% used a conventional insulin pump and 36% used a sensor-augmented insulin pump. The median glycated haemoglobin (HbA_1c) level was 60 mmol/mol (7.6%). The HbA_1c target (i.e. <58 mmol/mol for age <18 years and <53 mmol/mol for age >18 years) was achieved in 43.4% of paediatric and 23% of adult participants. Factors such as advanced pump functions, higher rate of sensor use, pregnancy in the year before the study and longer duration of diabetes were associated with lower HbA_1c levels. The most common chronic complications occurring in diabetes were retinopathy, microalbuminuria and hypertension. In the year before the study, 5% of participants reported ≥1 episode of severe hypoglycaemic (SH) episodes (SH) and 2.6% reported ≥1 episode of ketoacidosis.

CONCLUSIONS

Advanced personal skills and use of sensor-based pump are associated with better metabolic control outcomes in Italian people with diabetes who were treated with CSII. The reduction in SH episodes confirms the positive effect of CSII on hypoglycaemia.

CLINICAL TRIAL REGISTRATION NUMBER

NCT 02620917 (ClinicalTrials.gov).

Teleconsultation in type 1 diabetes mellitus (TELEDIABE)

AIMS

The growing incidence of diabetes and the need to contain healthcare costs empower the necessity to identify new models of care. Telemedicine offers an acknowledged instrument to provide clinical health care at a distance, increasing patient compliance and the achievement of therapeutical goals. The objective was to test the feasibility and the efficacy in the improvement of the glycemic control of the teleconsultation for patients with type 1 diabetes mellitus.

METHODS

A randomized open-label, parallel arms, controlled trial was conducted in two diabetes centers in Italy. Participants affected by type 1 diabetes mellitus have been randomly (1:1) assigned to receive their visits as standard or a web-based care. Patients in the teleconsultation group can arrange their appointments on a Web site and can also have access to web educational courses or to nutritional and psychological counseling. The primary outcome was the assessment of glycemic control by HbA1c measurement after a 12-month follow-up.

RESULTS

Overall 74 participants were followed for 1 year. HbA1c changes were not statistically different within (p = 0.56 for standard care group; p = 0.45 for telemedicine group) and between (p = 0.60) groups when considering differences from baseline to the end of the study. Patients randomized to teleconsultation reported reduced severe hypoglycemic episodes (p = 0.03). In addition, they were largely satisfied with the activities, perceived a good improvement in the self-management of the diabetes, and reported to have a time saving and a cost reduction.

CONCLUSIONS

In conclusion, TELEDIABE proposes a new system for the management of patients with type 1 diabetes mellitus.

Idiopathic Intracranial Hypertension (Pseudotumor Cerebri): Descriptive Epidemiology, Clinical Features, and Visual Outcome in Parma, Italy, 1990 to 1999

Purpose

To ascertain the annual incidence rate and the clinical features, other than visual outcome, of idiopathic intracranial hypertension (IIH) in Parma, northern Italy.

METHODS

Neurologic care of people living in the Parma area is entirely provided by one private and two public hospitals. Medical records related to IIH were retrospectively reviewed for all Parma residents from 1990 through 1999.

Results

Ten patients (8 women and 2 men) were identified as having IIH according to modified Dandy criteria. Their age ranged from 16 to 53 years with a mean of 36 years at diagnosis. The annual age-adjusted rate per 100,000 is 0.28 for the total population. For women in reproductive age, the annual incidence rate is 0.65/100,000. For overweight women in reproductive age, the annual incidence rate is 2.7/100,000.

CONCLUSIONS

The incidence rate found in this study is lower than the incidence reported in previous US and Libyan studies. A significant difference in overweight distribution is observed comparing percentage of body weight between US and Parma populations. As overweight and obesity are important factors contributing to IIH development, it is possible that their low percentage in the Parma population may, at least partially, explain the low IIH incidence observed.

Ultrasound characterization of insulin induced lipohypertrophy in type 1 diabetes mellitus

OBJECTIVE

Subcutaneous insulin absorption is one of the key factors affecting glycemic control in patients with diabetes mellitus under insulin therapy. Insulin-induced subcutaneous lipohypertrophy has been reported to impair insulin regular absorption and hence glycemic control. So far, lipohypertrophy diagnosis has only been clinical. This study aims at evaluating the possible role of ultrasound scan in the assessment of subcutaneous lipohypertrophy in patients affected by type 1 diabetes mellitus.

METHODS

A pilot observational retrospective study was performed in 20 patients affected by type 1 diabetes mellitus. In these patients the areas with clinical evidence of lipohypertrophy dependent on the insulin injections were characterized by the presence of tissues that at the ultrasound scan resulted similar to fibrotic tissues (hyperechogenic) or to an interstitial edema or to fat tissues (hypoechogenic). It was utilized a multi frequency linear probe (6-18 MHz). The patients were advised to avoid insulin injections on the areas with lipohypertrophy scanned by the ultrasound and the HbA1c changes were evaluated 3 months later.

RESULTS

The lipohypertrophic areas presented at least three different aspects upon ultrasound assessment: the iso-hyperechogenic one, with a predominant fibrotic component; the isoechogenic one, with "large tangles" fibrotic elements and the iso-hypoechogenic aspect with no fibrotic elements. When patients were advised to avoid insulin injections on areas with lipohypertrophy defined by ultrasound scan, 3 months after the first evaluation HbA1c had significantly improved (basal HbA1c 7.87 ± 0.56 versus 7.67 ± 0.52 3 months later, p = 0.029). No significant improvements of the HbA1c were found in the control matched group in which lipohypertrophy was only clinically valued through inspection and palpation.

CONCLUSIONS

Ultrasound scan can help identify and characterize the lipohypertrophic areas and this might be useful to improve glycemic control.

Unintended Insulin Pump Delivery in Hyperbaric Conditions

AIMS/HYPOTHESIS

Unintended pump insulin delivery was reported to occur as a consequence of decreased atmospheric pressure, probably mediated by air bubble formation and the expansion of existing bubbles. This observation has been used to explain some hypoglycemic episodes occurring in patients on insulin pump treatment in between 1 and 1 h 45 min after the flight takeoff. New models of insulin pumps have been introduced in the market, most of them are waterproof certified. It is not clear if in these new pumps the influence of atmospheric pressure changes on the insulin delivery is still present. Moreover, there are no evidences related to the insulin pump operations in hyperbaric conditions, like as during diving activities. Our aim is therefore to verify the eventual variation of insulin pump delivery determined by atmospheric pressure changes in hyperbaric conditions.

METHODS

Three new models of insulin pumps were tested in hyperbaric conditions at a flow rate of 2 U/h.

RESULTS

Atmospheric pressure variation affected pump insulin release. An increase in the atmospheric pressure from 1 to 1.3 atmosphere (ATA) induced a decrease of pump basal insulin release (about -0.2 U/10 min); conversely, when the atmospheric pressure returned from 1.3 to 1 ATA, an unintended insulin delivery was observed (about +0.3 U/10 min). This phenomenon appeared to be independent of the insulin pump rate and dependent on the presence of air bubbles within the insulin tube setting and cartridge.

CONCLUSIONS

Unintended insulin delivery driven by atmospheric pressure changes in hyperbaric conditions occurred in the new insulin pumps available. Patients should pay attention to possible variation of insulin rate during the flight or during diving activities.

Islet Transplantation in Pediatric Patients: Current Indications and Future Perspectives

The first islet transplantation in diabetes mellitus was performed more than 20 years ago. Since then, clinical results have progressively improved. Nowadays, islet transplantation can be considered a real therapeutic option after pancreatectomy for painful chronic pancreatitis (autotransplantation) and in selected adult patients affected by type 1 diabetes mellitus (allotransplantation). Better results are mainly due to the advances in the standardization of islet isolation and purification procedures as well as in the pharmacological treatment of recipients. Anti-inflammatory treatments facilitate islet engraftment and prevent metabolic exhaustion and functional β-cell apoptosis; new strategies better control islet graft rejection. As a consequence, islet transplantation activities are no longer confined to few centers only, rather thousands of transplants are now performed all over the world. Many attempts are actually undertaken to find solutions to current problems of islets transplantation, from toxicity of immunosuppressive therapy to the limited engraftment, function and duration. There is general hope that these procedures will offer a safe and feasible therapeutic option for an increasing number of patients suffering from diabetes mellitus, including pediatric patients.

Delta cell death in the islet of Langerhans and the progression from normal glucose tolerance to type 2 diabetes in non-human primates (baboon, Papio hamadryas)

AIMS/HYPOTHESIS

The cellular composition of the islet of Langerhans is essential to ensure its physiological function. Morphophysiological islet abnormalities are present in type 2 diabetes but the relationship between fasting plasma glucose (FPG) and islet cell composition, particularly the role of delta cells, is unknown. We explored these questions in pancreases from baboons (Papio hamadryas) with FPG ranging from normal to type 2 diabetic values.

METHODS

We measured the volumes of alpha, beta and delta cells and amyloid in pancreatic islets of 40 baboons (Group 1 [G1]: FPG < 4.44 mmol/l [n = 10]; G2: FPG = 4.44-5.26 mmol/l [n = 9]; G3: FPG = 5.27-6.94 mmol/l [n = 9]; G4: FPG > 6.94 mmol/l [n = 12]) and correlated islet composition with metabolic and hormonal variables. We also performed confocal microscopy including TUNEL, caspase-3, and anti-caspase cleavage product of cytokeratin 18 (M30) immunostaining, electron microscopy, and immuno-electron microscopy with anti-somatostatin antibodies in baboon pancreases.

RESULTS

Amyloidosis preceded the decrease in beta cell volume. Alpha cell volume increased ∼ 50% in G3 and G4 (p < 0.05), while delta cell volume decreased in these groups by 31% and 39%, respectively (p < 0.05). In G4, glucagon levels were higher, while insulin and HOMA index of beta cell function were lower than in the other groups. Immunostaining of G4 pancreatic sections with TUNEL, caspase-3 and M30 showed apoptosis of beta and delta cells, which was also confirmed by immuno-electron microscopy with anti-somatostatin antibodies.

CONCLUSIONS/INTERPRETATION

In diabetic baboons, changes in islet composition correlate with amyloid deposition, with increased alpha cell and decreased beta and delta cell volume and number due to apoptosis. These data argue for an important role of delta cells in type 2 diabetes.

A possible role of transglutaminase 2 in the nucleus of INS-1E and of cells of human pancreatic islets

Transglutaminase 2 (TG2) is a multifunctional protein with Ca^2 +-dependent transamidating and G protein activity. Previously we reported that the role of TG2 in insulin secretion may involve cytoplasmic actin remodeling and a regulative action on other proteins during granule movement. The aim of this study was to gain a better insight into the role of TG2 transamidating activity in mitochondria and in the nucleus of INS-1E rat insulinoma cell line (INS-1E) during insulin secretion. To this end we labeled INS-1E with an artificial donor (biotinylated peptide), in basal condition and after stimulus with glucose for 2, 5, and 8 min. Biotinylated proteins of the nuclear/mitochondrial-enriched fraction were analyzed using two-dimensional electrophoresis and mass spectrometry. Many mitochondrial proteins involved in Ca^2 + homeostasis (e.g. voltage-dependent anion-selective channel protein, prohibitin and different ATP synthase subunits) and many nuclear proteins involved in gene regulation (e.g. histone H3, barrier to autointegration factor and various heterogeneous nuclear ribonucleoprotein) were identified among a number of transamidating substrates of TG2 in INS-1E. The combined results provide evidence that a temporal link exists between glucose-stimulation, first phase insulin secretion and the action of TG on histone H3 both in INS-1E and human pancreatic islets.

Biological significance

Research into the role of transglutaminase 2 during insulin secretion in INS-1E rat insulinoma cellular model is depicting a complex role for this enzyme. Transglutaminase 2 acts in the different INS-1E compartments in the same way: catalyzing a post-translational modification event of its substrates. In this work we identify some mitochondrial and nuclear substrates of INS-1E during first phase insulin secretion. The finding that TG2 interacts with nuclear proteins that include BAF and histone H3 immediately after (2–5 min) glucose stimulus of INS-1E suggests that TG2 may be involved not only in insulin secretion, as suggested by our previous studies in cytoplasmic INS-1E fraction, but also in the regulation of glucose-induced gene transcription.

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Transglutaminase 2 localizes in the nucleus and in the mitochondrion of INS-1E.

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TG2 acts as a modifying enzyme in both compartments during FPIS.

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TG2 may contribute to Ca^2 + sensing in mitochondrion through its substrates.

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TG2 may contribute to chromatin condensation in nucleus through its substrates.

Serological Proteome Analysis (SERPA) as a tool for the identification of new candidate autoantigens in type 1 diabetes

Type 1 diabetes (T1D) is an autoimmune disease characterized by the presence of circulating autoantibodies directed against proteins of islet beta-cell. Autoantibody testing is used for diagnostic purposes; however, up to 2-5% of patients who are clinically diagnosed with T1D are found negative for known antibodies, suggesting that the T1D autoantigen panel is incomplete. With the aim of identifying new T1D autoantigen(s), we used sera from subjects clinically diagnosed with T1D, but who tested negative for the four T1D autoantibodies currently used in clinical practice and for genes responsible for sporadic cases of diabetes. Sera from these patients were challenged by Western blot against the proteome from human pancreatic beta-cells resolved by 2DE. Eleven proteins were identified by MS. A radiobinding assay (RBA) was developed to test the reactivity to Rab GDP dissociation inhibitor beta (GDIβ) of T1D sera using an independent method. Depending on the construct used (open reading frame or COOH-terminus) 22% to 32% of fifty T1D sera showed increased binding to GDIβ by RBA. In addition, 15% of patients with celiac disease had raised binding to the COOH-terminus GDIβ. These results indicate that immunoproteomics is a feasible strategy for the identification of candidate T1D autoantigens.

BIOLOGICAL SIGNIFICANCE

Several approaches have been previously used to look for new type 1 diabetes autoantigens. With the present work we show that carefully selected sera from rare patients with diabetes both negative for the 5 autoantibodies currently used in clinical practice and for genes responsible for sporadic cases of diabetes, may be exploited in experiments utilizing human pancreatic islets extracts as a target for SERPA to identify novel candidate T1D autoantigens.

Transglutaminase 2 transamidation activity during first-phase insulin secretion: natural substrates in INS-1E

Transglutaminase 2 (TG2) is a multifunctional protein with Ca(2+)-dependent transamidating and G protein activity. Previously, we reported that tgm2 -/- mice have an impaired insulin secretion and that naturally occurring TG2 mutations associated with familial, early-onset type 2 diabetes, show a defective transamidating activity. Aim of this study was to get a better insight into the role of TG2 in insulin secretion by identifying substrates of TG2 transamidating activity in the pancreatic beta cell line INS-1E. To this end, we labeled INS-1E that are capable of secreting insulin upon glucose stimulation in the physiologic range, with an artificial acyl acceptor (biotinamido-pentylamine) or donor (biotinylated peptide), in basal condition and after stimulus with glucose for 2, 5, and 8 min. Biotinylated proteins were analyzed by two-dimensional electrophoresis and mass spectrometry. In addition, subcellular localization of TG2 in human endocrine pancreas was studied by electron microscopy. Among several TG2's transamidating substrates in INS-1E, mass spectrometry identified cytoplasmic actin (a result confirmed in human pancreatic islet), tropomyosin, and molecules that participate in insulin granule structure (e.g., GAPDH), glucose metabolism, or [Ca(2+)] sensing (e.g., calreticulin). Physical interaction between TG2 and cytoplasmic actin during glucose-stimulated first-phase insulin secretion was confirmed by co-immunoprecipitation. Electron microscopy revealed that TG2 is localized close to insulin and glucagon granules in human pancreatic islet. We propose that TG2's role in insulin secretion may involve cytoplasmic actin remodeling and may have a regulative action on other proteins during granule movement. A similar role of TG2 in glucagon secretion is also suggested.

Human placental lactogen (hPL-A) activates signaling pathways linked to cell survival and improves insulin secretion in human pancreatic islets

The search for factors either promoting islets proliferation or survival during adult life is a major issue for both type 1 and 2 diabetes mellitus. Among factors with mitogenic activity on pancreatic β-cells, human placental lactogen (hPL) showed stronger activity when compared to the other lactogen hormones: growth hormone (GH) and prolactin (PRL). The aim of the present work is to elucidate the biological and molecular events of hPL isoform A (hPL-A) activity on human cultured islets. We used pure human pancreatic islets and insulinoma cell lines (βTC-1 and RIN, murine and rat respectively) stimulated with hPL-A recombinant protein and we compared hPL-A activity with that of hGH. We showed that hPL-A inhibits apoptosis, both in insulinoma and human islets, by the phosphorylation of AKT protein. Indeed, the antiapoptotic role of hPL-A was mediated by PI3K, p38 and it was independent by PKA, Erk1/2. Compared with hGH, hPL-A modulated at different intervals and/or intensity by the phosphorylation of JAKs/STATs and MAPKinases. Moreover, hPL-A induced PDX-1 intracellular expression, improving beta cell activity and ameliorating insulin secretion in response to high glucose stimulation. Our data support the idea that hPL-A is involved in the regulation of beta cells activity. Importantly, we found that hPL-A can preserve and improve the ability of purified human pancreatic islets cultured to secrete insulin in vitro.

The glial glutamate transporter 1 (GLT1) is expressed by pancreatic beta-cells and prevents glutamate-induced beta-cell death

Glutamate is the major excitatory neurotransmitter of the central nervous system (CNS) and may induce cytotoxicity through persistent activation of glutamate receptors and oxidative stress. Its extracellular concentration is maintained at physiological concentrations by high affinity glutamate transporters of the solute carrier 1 family (SLC1). Glutamate is also present in islet of Langerhans where it is secreted by the α-cells and acts as a signaling molecule to modulate hormone secretion. Whether glutamate plays a role in islet cell viability is presently unknown. We demonstrate that chronic exposure to glutamate exerts a cytotoxic effect in clonal β-cell lines and human islet β-cells but not in α-cells. In human islets, glutamate-induced β-cell cytotoxicity was associated with increased oxidative stress and led to apoptosis and autophagy. We also provide evidence that the key regulator of extracellular islet glutamate concentration is the glial glutamate transporter 1 (GLT1). GLT1 localizes to the plasma membrane of β-cells, modulates hormone secretion, and prevents glutamate-induced cytotoxicity as shown by the fact that its down-regulation induced β-cell death, whereas GLT1 up-regulation promoted β-cell survival. In conclusion, the present study identifies GLT1 as a new player in glutamate homeostasis and signaling in the islet of Langerhans and demonstrates that β-cells critically depend on its activity to control extracellular glutamate levels and cellular integrity.

A new method to value efficiency of enzyme blends for pancreatic tissue digestion

Islet transplantation, since the 1990s, has been an example of human cell therapy. Nevertheless, the islet isolation procedure is not completely standardized; in fact, >50% of islet procedures do not eventuate in transplantation due both to the variability of a donor's pancreas and to the unpredictable efficiency of an enzymatic blend. The enzymes used in pancreas isolation to digest several substrates are extracted from Clostridium histolyticum. In particular, they have strong collagenolytic activity compared with vertebrate collagenases. However, several impediments persist in human islet isolation success, probably owing to the variable composition and concentration of collagenases employed during the digestion phase. For islet isolation processes, neutral proteases play important roles. However, they should be considered to be double-edged swords, contributing to tissue dissociation but, sometimes, decreasing islet yield through fragmentation, breakdown, and inactivation. Protease activities cannot be preciously adjusted in a narrow range, there is no approach to determine the optimal dosage and composition of enzymes for extraction of human islets from the pancreas. At this time, available data on commercial enzymatic activity are not sufficient to predict their efficiency for pancreas digestion; consequently, it is difficult to select enzyme batches. For these reasons, we sought to generate an innovative evaluation assay to select enzymes useful for isolation procedures of pancreatic islets.

Temporal clustering for blood glucose analysis in the ICU: identification of groups of patients with different risk profile

Blood Glucose (BG) analysis and control in critically ill patients became an important research challenge in the last few years. Despite the big improvements that have been achieved both in research and in clinical practice, there are still many aspects that need to be elucidated. A first step towards a better comprehension of the phenomena underlying BG dynamics is represented by the study of retrospectively collected data. In this paper we propose an analysis of blood glucose time series through a combined temporal clustering and standard statistical analysis approach. The ultimate goal of the analysis is the identification of groups of patients showing different BG dynamics and evaluate their risk profiles, which is a very important issue in the Intensive Care Units. The method is applied to a set of patients treated at the Mediterranean Institute for Transplantation and Advanced Specialized Therapies in Palermo, Italy. We show that it is possible to identify two groups based on the initial blood glucose trends, and that the two groups significantly differ in terms of their future BG behaviour.