The Role of Human IAPP in Stress and Inflammatory Processes in Type 2 Diabetes

Understanding the mechanisms regulating whole-body glucose homeostasis is important in order to understand what happens in a disease such as type 2 diabetes (T2D). Insulin resistance, inflammation, dysfunction of islet β-cells, and the presence of amyloid deposits in the pancreas are some of the major causes involved in the process of β-cell deterioration. The unique peptide constituent of amyloid deposits, human islet amyloid polypeptide (hIAPP), is capable of inducing endoplasmic reticulum (ER) stress and the resulting unfolded-protein response activation. Additionally, hIAPP has been shown to induce interleukin-1β expression, the main cytokine involved in inflammation and T2D causing inflammation and eventually, inducing apoptosis. Nevertheless, the mechanisms behind the process of hIAPP aggregation and amyloid formation are still unknown. In this chapter, we describe the different mechanisms by which hIAPP induces ER stress and inflammation. This should open the door for designing therapeutic interventions aimed at modulating the immune system and the ER stress response

Treatment with EV-miRNAs Alleviates Obesity-Associated Metabolic Dysfunction in Mice

Most cells release extracellular vesicles (EVs) that can be detected circulating in blood. We and others have shown that the microRNA contents of these vesicles induce transcriptomic changes in acceptor cells, contributing to the adjustment of metabolic homeostasis in response to environmental demands. Here, we explore the potential for modulating obesity- and exercise-derived EV-microRNAs to treat the metabolic dysfunction associated with obesity in mice. Treatment with EV-miRNAs alleviated glucose intolerance and insulin resistance in obese mice to an extent similar to that of high-intensity interval training, although only exercise improved cardiorespiratory fitness and decreased body weight. Mechanistically, EV-miRNAs decreased fatty acid and cholesterol biosynthesis pathways in the liver, reducing hepatic steatosis and increasing insulin sensitivity, resulting in decreased glycemia and triglyceridemia. Our data suggest that manipulation of EV-miRNAs may be a viable strategy to alleviate metabolic dysfunction in obese and diabetic patients who are unable to exercise, although actual physical activity is needed to improve cardiorespiratory fitness

The continuous glucose monitoring system is useful for detecting unrecognized hypoglycemias in patients with type 1 and type 2 diabetes but is not better than frequent capillary glucose measurements for improving metabolic control

WSTĘP. Celem pracy było określenie przydatności systemu ciągłego monitorowania glikemii (CGMS, continuous glucose monitoring system) w wykrywaniu częstości nierozpoznawalnych niedocukrzeń u chorych na cukrzycę typu 1 i 2 oraz jako metody umożliwiającej uzyskanie poprawy wyrównania metabolicznego u chorych na cukrzycę typu 1. MATERIAŁ I METODY. Badaniu poddano 70 chorych na cukrzycę (typu 1 &#8212; 40 osób i typu 2 &#8212; 30 osób), u których zastosowano CGMS. Rejestracji podlegały nierozpoznane epizody hipoglikemii. W badaniu wzięła również udział grupa 40 chorych na cukrzycę typu 1, u których zmodyfikowano leczenie na podstawie pomiarów za pomocą CGMS. Pacjentów tych porównano z grupą kontrolną &#8212; chorych na cukrzycę typu 1 prowadzących intensywną samokontrolę. Wartością mierzoną było stężenie hemoglobiny glikowanej (HbA1c) przed rozpoczęciem badania i po 3 miesiącach. WYNIKI. U 62,5% chorych na cukrzycę typu 1 i u 46,4% chorych na cukrzycę typu 2 metoda CGMS umożliwiła wykrycie nierozpoznawalnych niedocukrzeń. Do 73,7% wszystkich epizodów hipoglikemii doszło w godzinach nocnych. Zarówno w grupie pacjentów stosujących CGMS, jak i w grupie kontrolnej stężenie HbA1c istotnie się obniżyło (odpowiednio z 8,3 &plusmn; 1,6 do 7,5 &plusmn; 1,2%, p < 0,01 i z 8,0 &plusmn; 1,4 do 7,5 &plusmn; 0,8%, p < 0,01). Największą redukcję stężenia HbA1c obserwowano w podgrupie, która rozpoczęła leczenie ciągłym podskórnym wlewem insuliny &#8212; także w grupach badanej i kontrolnej (odpowiednio z 9,4 &plusmn; 2 do 7,2 &plusmn; 1,4% i z 8,1 &plusmn; 1,8 do 7,1 &plusmn; 0,6%). WNIOSKI. System stałego monitorowania glikemii jest przydatny w wykrywaniu nierozpoznawalnych niedocukrzeń u chorych na cukrzycę typu 1 i 2. Niezależnie od metody leczenia nie stwierdzono jednak jego przewagi nad metodą standardowej samokontroli w zakresie poprawy wyrównania metabolicznego u chorych na cukrzycę typu 1.INTRODUCTION. To evaluate whether the continuous glucose monitoring system (CGMS; MiniMed, Sylmar, CA) is useful for investigating the incidence of unrecognized hypoglycemias in type 1 and type 2 diabetic patients and for improving metabolic control in type 1 diabetic patients. MATERIAL AND METHODS. A total of 70 diabetic subjects (40 type 1 and 30 type 2 subjects) were monitored using the CGMS. The number of unrecognized hypoglycemias was registered. Furthermore, the 40 type 1 diabetic patients whose treatment was modified in accordance with the information obtained from the CGMS were compared with a control group of 35 different type 1 diabetic patients using intensive capillary glucose measurements. HbA1c levels were measured before the monitoring period and 3 months later. RESULTS. The CGMS detected unrecognized hypoglycemias in 62.5% of the type 1 diabetic patients and in 46.6% of the type 2 diabetic patients. We found that 73.7% of all events occurred at night. HbA1c concentrations decreased significantly in both the group of type 1 diabetic subjects monitored with the CGMS (from 8.3 &#177; 1.6 to 7.5 &#177; 1.2%, P < 0.01) and the control group (from 8.0 &#177; 1.4 to 7.5 &#177; 0.8%, P < 0.01). The greatest reduction was observed in the subgroup of patients who started continuous subcutaneous insulin infusion therapy, both in the CGMSmonitored and control groups (from 9.4 &#177; 2 to 7.2 &#177; &#177; 1.4% and from 8.1 &#177; 1.8 to 7.1 &#177; 0.6%, respectively). CONCLUSIONS. The CGMS is useful for detecting unrecognized hypoglycemias in type 1 and type 2 diabetic subjects; however, it is not better than standard capillary glucose measurements for improving metabolic control of type 1 diabetic subjects, regardless of the therapeutic regimen

Coxsackievirus B Type 4 Infection in beta Cells Downregulates the Chaperone Prefoldin URI to Induce a MODY4-like Diabetes via Pdx1 Silencing

Enteroviruses are suspected to contribute to insulin-producing beta cell loss and hyperglycemia-induced diabetes. However, mechanisms are not fully defined. Here, we show that coxsackievirus B type 4 (CVB4) infection in human islet-engrafted mice and in rat insulinoma cells displays loss of unconventional prefoldin RPB5 interactor (URI) and PDX1, affecting beta cell function and identity. Genetic URI ablation in the mouse pancreas causes PDX1 depletion in beta cells. Importantly, diabetic PDX1 heterozygous mice overexpressing URI in beta cells are more glucose tolerant. Mechanistically, URI loss triggers estrogen receptor nuclear translocation leading to DNA methyltransferase 1 (DNMT1) expression, which induces Pdx1 promoter hypermethylation and silencing. Consequently, demethylating agent procainamide-mediated DNMT1 inhibition reinstates PDX1 expression and protects against diabetes in pancreatic URI-depleted mice . Finally, the beta cells of human diabetes patients show correlations between viral protein 1 and URI, PDX1, and DNMT1 levels. URI and DNMT1 expression and PDX1 silencing provide a causal link between enterovirus infection and diabetes

Coxsackievirus B Type 4 Infection in β Cells Downregulates the Chaperone Prefoldin URI to Induce a MODY4-like Diabetes via Pdx1 Silencing.

Enteroviruses are suspected to contribute to insulin-producing β cell loss and hyperglycemia-induced diabetes. However, mechanisms are not fully defined. Here, we show that coxsackievirus B type 4 (CVB4) infection in human islet-engrafted mice and in rat insulinoma cells displays loss of unconventional prefoldin RPB5 interactor (URI) and PDX1, affecting β cell function and identity. Genetic URI ablation in the mouse pancreas causes PDX1 depletion in β cells. Importantly, diabetic PDX1 heterozygous mice overexpressing URI in β cells are more glucose tolerant. Mechanistically, URI loss triggers estrogen receptor nuclear translocation leading to DNA methyltransferase 1 (DNMT1) expression, which induces Pdx1 promoter hypermethylation and silencing. Consequently, demethylating agent procainamide-mediated DNMT1 inhibition reinstates PDX1 expression and protects against diabetes in pancreatic URI-depleted mice . Finally, the β cells of human diabetes patients show correlations between viral protein 1 and URI, PDX1, and DNMT1 levels. URI and DNMT1 expression and PDX1 silencing provide a causal link between enterovirus infection and diabetes.Human diabetic pancreatic samples and data were obtained from the CNIO Biobank thanks to the help of Maria-Jesus Artiga and from Biobanc-Mur, MarBiobank, Vasque Biobank, and Andalusian Public Health System Biobank, integrated in the Spanish Biobank Network and funded by Instituto de Salud Carlos III. We are also thankful to the Biobank of IDIBAPS, Barcelona, for providing samples to A.N. Samples were processed following standard operating procedures with the appropriate approval of the Ethics and Scientific Committees. We also thank the CNIO Mouse Genome Editing Core Unit as well as the CNIO Genomics Unit for their support. We are also thankful to Dr. K. Qvortrup (University of Copenhagen, Denmark) for the electron microscopy. This work was funded by grant to J.P.W. supported by the National Institutes of Health NIAID/NIDDK R01 AI116920, and by grants to N.D. supported by the EFSD/JRDF/Lilly Programme through the European Foundation for the Study of Diabetes (EFSD) and and by the State Research Agency (AEI, 10.13039/501100011033) from the Spanish Ministry of Science and Innovation (projects SAF2016-76598-R, SAF2017-92733-EXP, and RTI2018-094834-B-I00) through the European Regional Development Fund (ERDF). This work was developed at the CNIO, which is funded by the Health Institute Carlos III (ISCIII) and the Spanish Ministry of Science and Innovation.S

Effect of α-lipoic acid and exercise training on cardiovascular disease risk in obesity with impaired glucose tolerance

Obese subjects with impaired glucose tolerance (IGT) are more susceptible than healthy individuals to oxidative stress and cardiovascular disease. This randomised controlled investigation was designed to test the hypothesis that α-lipoic acid supplementation and exercise training may elicit favourable clinical changes in obese subjects with IGT. All data were collected from 24 obese (BMI ≥ 30 kg/m2) IGT patients. Following participant randomisation into two groups, fasting venous blood samples were obtained at baseline, and before and following intervention. The first group consisted of 12 participants who completed a 12 week control phase followed by 12 weeks of chronic exercise at 65% HRmax for 30 minutes a day, 5 days per week, while ingesting 1 gram per day of α-lipoic acid for 12 weeks. The second group consisted of 12 participants who completed the same 12 week control phase, but this was followed by 12 weeks of 1 gram per day of α-lipoic acid supplementation only (no exercise). The main findings show a comparatively greater rate of low density lipoprotein (LDL) oxidation in the group consisting of α-lipoic acid only (p < 0.05 vs. pre intervention), although total oxidant status was lower post intervention (p < 0.05 vs. baseline) in this group. However, exercise and α-lipoic acid in combination attenuates LDL oxidation. Furthermore, in the α-lipoic acid supplement plus exercise training group, total antioxidant capacity was significantly increased (p < 0.05 vs. baseline and pre intervention). Body fat percentage and waist and hip circumference decreased following exercise training (p < 0.05 vs. post intervention). There were no selective treatment differences for a range of other clinical outcomes including glycaemic regulation (p > 0.05). These findings report that α-lipoic acid ingestion may increase the atherogenicity of LDL when ingested in isolation of exercise, suggesting that in IGT the use of this antioxidant treatment does not ameliorate metabolic disturbances, but instead may detrimentally contribute to the pathogenesis of atherosclerosis and development of CVD. However, when α-lipoic acid is combined with exercise, this atherogenic effect is abolished

Human serum versus human serum albumin supplementation in human islet pretransplantation culture: in vitro and in vivo assessment

There is conflicting evidence favoring both the use of human serum (HS) and of human serum albumin (HSA) in human islet culture. We evaluated the effects of HS versus HSA supplementation on 1) in vitro β-cell viability and function and 2) in vivo islet graft revascularization, islet viability, β-cell death, and metabolic outcome after transplantation. Islets isolated from 14 cadaveric organ donors were cultured for 3 days in CMRL 1066 medium supplemented with HS or HSA. After 3 days in culture, β-cell apoptosis was lower in HS group (1.41 ± 0.27 vs. 2.38 ± 0.39%, p = 0.029), and the recovery of islets was 77 ± 11% and 54 ± 1% in HS- and HSA-cultured groups, respectively. Glucose-stimulated insulin secretion (GSIS) was higher in HS group (29.4, range 10.4-99.9, vs. 22.3, range 8.7-70.6, p = 0.031). In vivo viability and revascularization was determined in HS- and HSA-cultured islets transplanted into the anterior chamber of the eye of Balb/c mice (n = 14), and β-cell apoptosis in paraffin-embedded mouse eyes. Islet viability and β-cell apoptosis were similar in both groups. Revascularization was observed in one graft (HS group) on day 10 after transplantation. Islet function was determined in streptozotocin (STZ)-diabetic nude mice (n = 33) transplanted with 2,000 IEQs cultured with HS or HSA that showed similar blood glucose levels and percentage of normoglycemic animals over time. In conclusion, human islets cultured in medium supplemented with HS showed higher survival in vitro, as well as islet viability and function. The higher in vitro survival increased the number of islets available for transplantation. However, the beneficial effect on viability and function did not translate into an improved metabolic evolution when a similar number of HSA- and HS-cultured islets was transplanted

In Situ LSPR Sensing of Secreted Insulin in Organ-on-Chip

Organ-on-a-chip (OOC) devices offer new approaches for metabolic disease modeling and drug discovery by providing biologically relevant models of tissues and organs in vitro with a high degree of control over experimental variables for high-content screening applications. Yet, to fully exploit the potential of these platforms, there is a need to interface them with integrated non-labeled sensing modules, capable of monitoring, in situ, their biochemical response to external stimuli, such as stress or drugs. In order to meet this need, we aim here to develop an integrated technology based on coupling a localized surface plasmon resonance (LSPR) sensing module to an OOC device to monitor the insulin in situ secretion in pancreatic islets, a key physiological event that is usually perturbed in metabolic diseases such as type 2 diabetes (T2D). As a proof of concept, we developed a biomimetic islet-on-a-chip (IOC) device composed of mouse pancreatic islets hosted in a cellulose-based scaffold as a novel approach. The IOC was interfaced with a state-of-the-art on-chip LSPR sensing platform to monitor the in situ insulin secretion. The developed platform offers a powerful tool to enable the in situ response study of microtissues to external stimuli for applications such as a drug-screening platform for human models, bypassing animal testing