Correlation between islet α cell function and peripheral neuropathy in patients with type 2 diabetes mellitus.

BACKGROUND: This study explored the correlation between pancreatic islet α cell function, as reflected by the plasma glucagon levels, and Diabetic Peripheral Neuropathy (DPN) in patients with Type 2 Diabetes Mellitus (T2DM). METHODS: A total of 358 patients with T2DM were retrospectively enrolled in this study and divided into the Non-DPN (NDPN) group (n = 220) and the DPN group (n = 138). All patients underwent an oral glucose tolerance test to detect levels of blood glucose, insulin and glucagon, and the Area Under the Curve (AUC) for Glucagon (AUCglu) was used to estimate the overall glucagon level. The Peripheral Nerve Conduction Velocity (PNCV), Amplitude (PNCA) and Latency (PNCL) were obtained with electromyography, and their Z scores were calculated. RESULTS: There were significant differences regarding the age, disease duration, serum levels of alanine aminotransferase, aspartate aminotransferase, urea nitrogen, high-density lipoprotein, and 2h-C peptide between these two groups (p < 0.05). The NDPN group had higher glucagon levels at 30, 60 and 120 min and AUCglu (p < 0.05). The Z-scores of PNCV and PNCA showed an increasing trend (p < 0.05), while the Z-score of PNCL showed a decreasing trend (p < 0.05). The glucagon levels were positively correlated with PNCV and PNCA, but negatively correlated with PNCL, with Gluca30min having the strongest correlation (p < 0.05). Gluca30min was independently related to PNCV, PNCL, PNCA and DPN, respectively (p < 0.05). The function of pancreatic α islet cells, as reflected by the plasma glucagon level, is closely related to the occurrence of DPN in T2DM patients. CONCLUSION: Gluca30min may be a potentially valuable independent predictor for the occurrence of DPN.

Update on the transdifferentiation of pancreatic cells into functional beta cells for treating diabetes.

The increasing global prevalence and associated comorbidities need innovative approaches for type 2 diabetes mellitus (T2DM) prevention and treatment. Genetics contributes significantly to T2DM susceptibility, and genetic counseling is significant in detecting and informing people about the diabetic risk. T2DM is also intricately linked to overnutrition and obesity, and nutritional advising is beneficial to mitigate diabetic evolution. However, manipulating pancreatic cell plasticity and transdifferentiation could help beta cell regeneration and glucose homeostasis, effectively contributing to the antidiabetic fight. Targeted modulation of transcription factors is highlighted for their roles in various aspects of pancreatic cell differentiation and function, inducing non-beta cells' conversion into functional beta cells (responsive to glucose). In addition, pharmacological interventions targeting specific receptors and pathways might facilitate cell transdifferentiation aiming to maintain or increase beta cell mass and function. However, the mechanisms underlying cellular reprogramming are not yet well understood. The present review highlights the primary transcriptional factors in the endocrine pancreas, focusing on transdifferentiation as a primary mechanism. Therefore, islet cell reprogramming, converting one cell type to another and transforming non-beta cells into insulin-producing cells, depends, among others, on transcription factors. It is a promising fact that new transcription factors are discovered every day, and their actions on pancreatic islet cells are revealed. Exploring these pathways associated with pancreatic development and islet endocrine cell differentiation could unravel the molecular intricacies underlying transdifferentiation processes, exploring novel therapeutic strategies to treat diabetes. The medical use of this biotechnology is expected to be achievable within a short time.

Vertical sleeve gastrectomy improves glucose-insulin homeostasis by enhancing ß-cell function and survival via FGF15/19.

Vertical sleeve gastrectomy (VSG) restores glucose homeostasis in obese mice and humans. In addition, the increased fibroblast growth factor (FGF)15/19 circulating level postsurgery has been implicated in this effect. However, the impact of FGF15/19 on pancreatic islets remains unclear. Using a diet-induced obese mice model, we demonstrate that VSG attenuates insulin hypersecretion in isolated pancreatic islets, likely due to morphological alterations in the endocrine pancreas such as reduction in islet, ß-cell, and α-cell mass. In addition, VSG relieves gene expression of endoplasmic reticulum (ER) stress and inflammation markers in islets from obese mice. Incubation of INS-1E ß-cells with serum from obese mice induced dysfunction and cell death, whereas these conditions were not induced with serum from obese mice submitted to VSG, implicating the involvement of a humoral factor. Indeed, VSG increased FGF15 circulating levels in obese mice, as well as the expression of FGF receptor 1 (Fgfr1) and its coreceptor ß-klotho (Klb), both in pancreatic islets from VSG mice and in INS-1E cells treated with the serum from these mice. Moreover, exposing INS-1E cells to an FGFR inhibitor abolished the effects of VSG serum on insulin secretion and cell death. Also, recombinant FGF19 prevents INS-1E cells from dysfunction and death induced by serum from obese mice. These findings indicate that the amelioration of glucose-insulin homeostasis promoted by VSG is mediated, at least in part, by FGF15/19. Therefore, approaches promoting FGF15/19 release or action may restore pancreatic islet function in obesity.NEW & NOTEWORTHY Vertical sleeve gastrectomy (VSG) decreases insulin secretion, endoplasmic reticulum (ER) stress, and inflammation in pancreatic islets from obese mice. In addition, VSG increased fibroblast growth factor (FGF)15 circulating levels in obese mice, as well as the expression of FGF receptor 1 (Fgfr1) and its coreceptor ß-klotho (Klb), both in pancreatic islets from VSG mice and in INS-1E ß-cells treated with the serum from these mice. Serum from operated mice protects INS-1E cells from dysfunction and apoptosis, which was mediated by FGF15/19.

Correlation between islet α cell function and peripheral neuropathy in patients with type 2 diabetes mellitus

Abstract Background: This study explored the correlation between pancreatic islet α cell function, as reflected by the plasma glucagon levels, and Diabetic Peripheral Neuropathy (DPN) in patients with Type 2 Diabetes Mellitus (T2DM). Methods: A total of 358 patients with T2DM were retrospectively enrolled in this study and divided into the Non-DPN (NDPN) group (n = 220) and the DPN group (n = 138). All patients underwent an oral glucose tolerance test to detect levels of blood glucose, insulin and glucagon, and the Area Under the Curve (AUC) for Glucagon (AUCglu) was used to estimate the overall glucagon level. The Peripheral Nerve Conduction Velocity (PNCV), Amplitude (PNCA) and Latency (PNCL) were obtained with electromyography, and their Z scores were calculated. Results: There were significant differences regarding the age, disease duration, serum levels of alanine aminotransferase, aspartate aminotransferase, urea nitrogen, high-density lipoprotein, and 2h-C peptide between these two groups (p < 0.05). The NDPN group had higher glucagon levels at 30, 60 and 120 min and AUCglu (p < 0.05). The Z-scores of PNCV and PNCA showed an increasing trend (p < 0.05), while the Z-score of PNCL showed a decreasing trend (p < 0.05). The glucagon levels were positively correlated with PNCV and PNCA, but negatively correlated with PNCL, with Gluca30min having the strongest correlation (p < 0.05). Gluca30min was independently related to PNCV, PNCL, PNCA and DPN, respectively (p < 0.05). The function of pancreatic α islet cells, as reflected by the plasma glucagon level, is closely related to the occurrence of DPN in T2DM patients. Conclusion: Gluca30min may be a potentially valuable independent predictor for the occurrence of DPN.

Transcriptional signature of islet neogenesis-associated protein peptide-treated rat pancreatic islets reveals induction of novel long non-coding RNAs.

Background: Diabetes mellitus is characterized by chronic hyperglycemia with loss of ß-cell function and mass. An attractive therapeutic approach to treat patients with diabetes in a non-invasive way is to harness the innate regenerative potential of the pancreas. The Islet Neogenesis-Associated Protein pentadecapeptide (INGAP-PP) has been shown to induce ß-cell regeneration and improve their function in rodents. To investigate its possible mechanism of action, we report here the global transcriptional effects induced by the short-term INGAP-PP in vitro treatment of adult rat pancreatic islets. Methods and findings: Rat pancreatic islets were cultured in vitro in the presence of INGAP-PP for 4 days, and RNA-seq was generated from triplicate treated and control islet samples. We performed a de novo rat gene annotation based on the alignment of RNA-seq reads. The list of INGAP-PP-regulated genes was integrated with epigenomic data. Using the new gene annotation generated in this work, we quantified RNA-seq data profiled in INS-1 cells treated with IL1ß, IL1ß+Calcipotriol (a vitamin D agonist) or vehicle, and single-cell RNA-seq data profiled in rat pancreatic islets. We found 1,669 differentially expressed genes by INGAP-PP treatment, including dozens of previously unannotated rat transcripts. Genes differentially expressed by the INGAP-PP treatment included a subset of upregulated transcripts that are associated with vitamin D receptor activation. Supported by epigenomic and single-cell RNA-seq data, we identified 9 previously unannotated long noncoding RNAs (lncRNAs) upregulated by INGAP-PP, some of which are also differentially regulated by IL1ß and vitamin D in ß-cells. These include Ri-lnc1, which is enriched in mature ß-cells. Conclusions: Our results reveal the transcriptional program that could explain the enhancement of INGAP-PP-mediated physiological effects on ß-cell mass and function. We identified novel lncRNAs that are induced by INGAP-PP in rat islets, some of which are selectively expressed in pancreatic ß-cells and downregulated by IL1ß treatment of INS-1 cells. Our results suggest a relevant function for Ri-lnc1 in ß-cells. These findings are expected to provide the basis for a deeper understanding of islet translational results from rodents to humans, with the ultimate goal of designing new therapies for people with diabetes.

Obese mothers supplemented with melatonin during gestation and lactation ameliorate the male offspring's pancreatic islet cellular composition and beta-cell function.

Melatonin supplementation to obese mothers during gestation and lactation might benefit the pancreatic islet cellular composition and beta-cell function in male offspring adulthood. C57BL/6 females (mothers) were assigned to two groups (n = 20/each) based on their consumption in control (C 17% kJ as fat) or high-fat diet (HF 49% kJ as fat). Mothers were supplemented with melatonin (Mel) (10 mg/kg daily) during gestation and lactation, or vehicle, forming the groups (n = 10/each): C, CMel, HF, and HFMel. The male offspring were studied, considering they only received the C diet after weaning until three months old. The HF mothers and their offspring showed higher body weight, glucose intolerance, insulin resistance, and low insulin sensitivity than the C ones. However, HFMel mothers and their offspring showed improved glucose metabolism and weight loss than the HF ones. Also, the offspring's higher expressions of pro-inflammatory markers and endoplasmic reticulum (ER) stress were observed in HF but reduced in HFMel. Contrarily, antioxidant enzymes were less expressed in HF but improved in HFMel. In addition, HF showed increased beta-cell mass and hyperinsulinemia but diminished in HFMel. Besides, the beta-cell maturity and identity gene expressions diminished in HF but enhanced in HFMel. In conclusion, obese mothers supplemented with melatonin benefit their offspring's islet cell remodeling and function. In addition, improving pro-inflammatory markers, oxidative stress, and ER stress resulted in better glucose and insulin levels control. Consequently, pancreatic islets and functioning beta cells were preserved in the offspring of obese mothers supplemented with melatonin.

Islet transplantation: overcoming the organ shortage.

BACKGROUND: Type 1 diabetes mellitus (T1D) is a condition resulting from autoimmune destruction of pancreatic ß cells, leading patients to require lifelong insulin therapy, which, most often, does not avoid the most common complications of this disease. Transplantation of isolated pancreatic islets from heart-beating organ donors is a promising alternative treatment for T1D, however, this approach is severely limited by the shortage of pancreata maintained under adequate conditions. METHODS: In order to analyze whether and how this problem could be overcome, we undertook a retrospective study from January 2007 to January 2010, evaluating the profile of brain-dead human pancreas donors offered to our Cell and Molecular Therapy NUCEL Center ( www.usp.br/nucel ) and the basis for organ refusal. RESULTS: During this time period, 558 pancreata were offered by the São Paulo State Transplantation Central, 512 of which were refused and 46 were accepted for islet isolation and transplantation. Due to the elevated number of refused organs, we decided to analyze the main reasons for refusal in order to evaluate the possibility of improving the organ acceptance rate. The data indicate that hyperglycemia, technical issues, age, positive serology and hyperamylasemia are the top five main causes for declination of a pancreas offer. CONCLUSIONS: This study underlines the main reasons to decline a pancreas offer in Sao Paulo-Brazil and provides some guidance to ameliorate the rate of eligible pancreas donors, aiming at improving the islet isolation and transplantation outcome. TRIAL REGISTRATION: Protocol CAPPesq number 0742/02/CONEP 9230.

Presencia de autoanticuerpos anti islotes pancreáticos en diabetes tipo 1 durante la edad pediátrica / Presence of anti-pancreatic islet autoantibodies in type 1 diabetes in children

En la Diabetes tipo 1 (DM1) la pérdida de células ß pancreáticas es consecuencia de un proceso de autoinmunidad que cursa con la presencia de autoanticuerpos anti-islotes pancreáticos (AAPs). Estos AAPs son marcadores útiles para la clasificación de la enfermedad. En un centro pediátrico de tercer nivel se analizó la frecuencia de presentación de GADA, IA-2A, ZnT8A e IAA en un grupo con reciente debut entre enero 2018 y agosto 2021 (n= 90). Además, se investigó la frecuencia de presentación y relación de los AAPs con la edad, sexo y tiempo de evolución en pacientes en seguimiento (n= 240). En el grupo de debut se obtuvo positividad de GADA, IA-2A, ZnT8A y IAA en 77,8; 60; 62 y 47,8% de los pacientes respectivamente, un 4% no presentó AAPs. El 95,6% de los pacientes presentaron al menos un AAPs positivo. La frecuencia de IAA en el grupo en debut fue mayor en menores de 5 años. En el grupo en seguimiento el 75,2% resultaron GADA positivo (85,7% en mujeres y 62,8% en varones) p<0,05. IA-2A y ZnT8A fueron positivos en 45 y 51.7% respectivamente. El 91% presentaron al menos un AAP positivo. En este grupo se evidenció una menor positividad en función del tiempo de evolución. Se pudo determinar la frecuencia de presentación de los AAPs en un grupo en debut y la relación con la edad, sexo y tiempo de evolución en pacientes en seguimiento. La determinación de APPs facilita la correcta clasificación y elección de la terapia adecuada (AU)

In type 1 diabetes (DM1) the loss of pancreatic ß-cells is a consequence of an autoimmune process that results in the presence of pancreatic anti-islet autoantibodies (PAAs). PAAs are useful markers for the classification of the disease. The frequency of presentation of GADA, IA-2A, ZnT8A, and IAA in a group with recent debut seen between January 2018 and August 2021 (n= 90) was analyzed in a tertiary pediatric center. In addition, we investigated the frequency of presentation and association of PAAs with age, sex, and time of evolution in patients in follow-up (n= 240). In the debut group, GADA, IA2A, ZnT8A, and IAA positivity was found in 77.8, 60, 62, and 47.8% of patients, respectively; no PAAs were observed in 4% of the patients. Overall, 95.6% presented at least one positive PAA. The frequency of IAA in the debut group was higher in children younger than 5 years. In the follow-up group, 75.2% were GADA positive (85.7% of females and 62.8% of males) p<0.05. IA-2A and ZnT8A were positive in 45 and 51.7% respectively. Ninety-one percent presented with at least one positive PAA. In this group, a lower positivity was evidenced as a function of the time of evolution. The frequency of presentation of PAAs in a debut group and the relationship with age, sex, and time of evolution in patients in follow-up was demonstrated. The assessment of PAAs facilitates the correct classification and choice of adequate therapy (AU)

Metabolic effect of low fluoride levels in the islets of NOD mice: integrative morphological, immunohistochemical, and proteomic analyses

Abstract Fluoride (F) has been widely used to control dental caries, and studies suggest beneficial effects against diabetes when a low dose of F is added to the drinking water (10 mgF/L). Objectives This study evaluated metabolic changes in pancreatic islets of NOD mice exposed to low doses of F and the main pathways altered by the treatment. Methodology In total, 42 female NOD mice were randomly divided into two groups, considering the concentration of F administered in the drinking water for 14 weeks: 0 or 10 mgF/L. After the experimental period, the pancreas was collected for morphological and immunohistochemical analysis, and the islets for proteomic analysis. Results In the morphological and immunohistochemical analysis, no significant differences were found in the percentage of cells labelled for insulin, glucagon, and acetylated histone H3, although the treated group had higher percentages than the control group. Moreover, no significant differences were found for the mean percentages of pancreatic areas occupied by islets and for the pancreatic inflammatory infiltrate between the control and treated groups. Proteomic analysis showed large increases in histones H3 and, to a lesser extent, in histone acetyltransferases, concomitant with a decrease in enzymes involved in the formation of acetyl-CoA, besides many changes in proteins involved in several metabolic pathways, especially energy metabolism. The conjunction analysis of these data showed an attempt by the organism to maintain protein synthesis in the islets, even with the dramatic changes in energy metabolism. Conclusion Our data suggests epigenetic alterations in the islets of NOD mice exposed to F levels comparable to those found in public supply water consumed by humans.

Insulinoma / Insulinoma

RESUMEN El insulinoma es un tumor poco frecuente de las células de los islotes pancreáticos, caracterizado por la proliferación de las células betas. Son tumores neuroendocrinos pancreáticos, generalmente benignos y de pequeño tamaño, caracterizados por el síndrome de hipersecreción de insulina con el desarrollo de hipoglucemia. La mayoría de estos tumores son esporádicos, solo alrededor de 15-30 % es hereditario; está asociado a enfermedades como la neoplasia endocrina múltiple tipo 1, o el síndrome de Von Hippel-Lindau. La incidencia de dicho tumor es de 3-10 casos por cada millón de habitantes. La edad media de aparición es entre 40-50 años de edad y es más frecuente en mujeres. El reconocimiento temprano y el diagnóstico adecuado de este tumor pancreático raro, son aspectos importantes pues es potencialmente curable con un tratamiento quirúrgico oportuno.

ABSTRACT Insulinoma is a rare pancreatic islet cell tumor characterized by proliferation of beta cells. They are pancreatic neuroendocrine tumors, generally benign and small in size, characterized by insulin hypersecretion syndrome with the development of hypoglycemia. Most of these tumors are sporadic, only about 15-30% are hereditary; it is associated with diseases such as multiple endocrine neoplasia type 1, or Von Hippel-Lindau syndrome. The incidence of this tumor is 3-10 cases per million inhabitants. The average age of onset is between 40-50 years of age and it is more frequent in women. Early recognition and proper diagnosis of this rare pancreatic tumor are important aspects, as it is potentially curable with timely surgical treatment.

Exposure to intrauterine diabetes and post-natal high-fat diet: Effects on the endocrine pancreas of adult rat female pups.

AIMS: To evaluate the morphological changes in the pancreatic islet cells of adult female pups born to diabetic rats and fed a high-fat diet. MAIN METHODS: Female Sprague-Dawley rats were distributed into four experimental groups (n = 10 animals/group): 1) female pups from non-diabetic dams and fed a standard diet (OC/SD), 2) female pups from non-diabetic dams and fed a high-fat (OC/HFD), 3) female pups from diabetic dams and fed a standard diet (OD/SD) and 4) female pups from diabetic dams and fed a high-fat diet (OD/HFD). In adulthood, the rats were submitted to the oral glucose tolerance test and later euthanized to collect the pancreas for the analysis of pancreatic islets. KEY FINDINGS: The OC/HFD and OD/SD groups showed an increased percentage of cells immunostained for insulin and a decreased percentage and intensity of staining for somatostatin. The OD/HFD group showed an increased percentage of cells immunostained for insulin and glucagon and a higher staining intensity for glucagon. There was a progressive increase in blood glucose in the OC/HFD, OD/SD, and OD/HFD groups. SIGNIFICANCE: The association between maternal diabetes and/or the administration of high-fat diet-induced changes in the pancreatic hormonal triad of female pups in adulthood. In turn, these changes in the pancreatic islets are not capable of causing decreased blood glucose in the offspring, contributing to the development of glucose intolerance in adulthood.

The evaluation of pancreas β-cell autoantibodies in non-diabetic COVID-19 patients

ABSTRACT Objective: This study aims to evaluate potential pancreas endocrine damage due to SARS-CoV-2 by measuring β-cell autoantibodies in COVID-19 patients. Subjects and methods: Between June and July 2020, 95 inpatients with a positive COVID-19 test result after polymerase-chain-reaction (PCR) and who met the inclusion criteria were enrolled in our study. Laboratory parameters that belong to glucose metabolism and β-cell autoantibodies, including anti-islet, anti-glutamic acid decarboxylase, and anti-insulin autoantibodies, were measured. β-cell autoantibodies levels of the patients were measured during COVID-19 diagnosis. Positive results were reevaluated in the 3rd month of control. Results: In the initial evaluation, 4 (4.2%) patients were positive for anti-islet autoantibody. Only one (1.1%) patient was positive for anti-glutamic acid decarboxylase autoantibody. No patient had positive results for anti-insulin autoantibody. FPG, HbA1c, and C-peptide levels were similar in patients who were split into groups regarding the initial positive or negative status of anti-islet and anti-GAD autoantibodies (p>0.05). In the 3rd month after the initial measurements, anti-islet autoantibody positivity of 2 (50%) of 4 patients and anti-glutamic acid decarboxylase positivity of 1 (100%) patient were persistent. Finally, 3 (3.1%) patients in the whole group were positive for anti-islet autoantibody in the 3rd month of control. No difference was determined between the initial and the 3rd month of parameters of glucose metabolism. Conclusion: Following an ongoing autoantibody positivity in the present study brings the mind that SARS-CoV-2 may be responsible for the diabetogenic effect. Clinicians should be aware of autoantibody-positive DM as a potential autoimmune complication in patients with SARS-CoV-2.

The evaluation of pancreas ß-cell autoantibodies in non-diabetic COVID-19 patients.

Objective: This study aims to evaluate potential pancreas endocrine damage due to SARS-CoV-2 by measuring ß-cell autoantibodies in COVID-19 patients. Subjects and methods: Between June and July 2020, 95 inpatients with a positive COVID-19 test result after polymerase-chain-reaction (PCR) and who met the inclusion criteria were enrolled in our study. Laboratory parameters that belong to glucose metabolism and ß-cell autoantibodies, including anti-islet, anti-glutamic acid decarboxylase, and anti-insulin autoantibodies, were measured. ß-cell autoantibodies levels of the patients were measured during COVID-19 diagnosis. Positive results were reevaluated in the 3rd month of control. Results: In the initial evaluation, 4 (4.2%) patients were positive for anti-islet autoantibody. Only one (1.1%) patient was positive for anti-glutamic acid decarboxylase autoantibody. No patient had positive results for anti-insulin autoantibody. FPG, HbA1c, and C-peptide levels were similar in patients who were split into groups regarding the initial positive or negative status of anti-islet and anti-GAD autoantibodies (p>0.05). In the 3rd month after the initial measurements, anti-islet autoantibody positivity of 2 (50%) of 4 patients and anti-glutamic acid decarboxylase positivity of 1 (100%) patient were persistent. Finally, 3 (3.1%) patients in the whole group were positive for anti-islet autoantibody in the 3rd month of control. No difference was determined between the initial and the 3rd month of parameters of glucose metabolism. Conclusion: Following an ongoing autoantibody positivity in the present study brings the mind that SARS-CoV-2 may be responsible for the diabetogenic effect. Clinicians should be aware of autoantibody-positive DM as a potential autoimmune complication in patients with SARS-CoV-2.

Islet amyloid toxicity: From genesis to counteracting mechanisms.

Islet amyloid polypeptide (IAPP or amylin) is a hormone co-secreted with insulin by pancreatic ß-cells and is the major component of islet amyloid. Islet amyloid is found in the pancreas of patients with type 2 diabetes (T2D) and may be involved in ß-cell dysfunction and death, observed in this disease. Thus, investigating the aspects related to amyloid formation is relevant to the development of strategies towards ß-cell protection. In this sense, IAPP misprocessing, IAPP overproduction, and disturbances in intra- and extracellular environments seem to be decisive for IAPP to form islet amyloid. Islet amyloid toxicity in ß-cells may be triggered in intra- and/or extracellular sites by membrane damage, endoplasmic reticulum stress, autophagy disruption, mitochondrial dysfunction, inflammation, and apoptosis. Importantly, different approaches have been suggested to prevent islet amyloid cytotoxicity, from inhibition of IAPP aggregation to attenuation of cell death mechanisms. Such approaches have improved ß-cell function and prevented the development of hyperglycemia in animals. Therefore, counteracting islet amyloid may be a promising therapy for T2D treatment.

Myricitrin and Its Solid Lipid Nanoparticle Increase Insulin Secretion and Content of Isolated Islets from the Pancreas of Male Mice

Abstract Glucose exposure induces toxic effects on the function of the pancreatic islets. Moreover, myricitrin as a flavonoid glycoside may have favorable effects on insulin secretion of Langerhans islets. The present study aimed to investigate the effect of Myricitrin and its solid lipid nanoparticles (SLN) on the insulin secretion as well as the content of isolated pancreatic islets from male mice. In this experimental study, Langerhans islets were separated from adult male NMRI mice using the collagenase method. The insulin secretion and content of islets were assessed in glucose-containing medium (2.8, 5.6, and 16.7mM). Further, islets treated were prepared by the administration of Myricitrin and its SLN (1, 3 and 10µM). Myricitrin 3µM, and SLN containing Myricitrin 3 and 10µM increased insulin secretion in medium containing glucose concentration 2.8mM. Accordingly, this variable increased in Myricitrin 3 and 10µM, SLN containing Myricitrin 1, 3, and 10µM utilization as well as glucose concentration 5.6mM. Afterward, the insulin secretion increased in medium containing 16.7mM glucose after the addition of Myricitrin and SLN containing Myricitrin 1, 3, and 10µM. Also, the insulin content increased in Myricitrin and SLN containing Myricitrin 1, 3, and 10µM administered groups in all medium containing glucose concentrations. Myricitrin and its SLN increased islets insulin secretion and content in low, moderate, and high glucose concentration mediums

Diferentes estrategias en la aplicación clínica de los trasplantes de islotes pancreáticos / Different strategies about clinical application of pancreatic islet transplantation

Resumen El trasplante clínico de islotes pancreáticos es un tratamiento para algunos pacientes con diabetes tipo 1 de difícil tratamiento. Se ha logrado restaurar la independencia de la insulina, sin embargo, en la mayoría de los casos es necesario repetir el trasplante, lo que implica el desarrollo de estrategias que permitan superar las limitaciones asociadas a este procedimiento y la integración de métodos que mitiguen la perdida de células con el fin de mejorar el resultado del trasplante. El objetivo es centrarnos en mejorar la eficacia en el trasplante de sistemas de microencapsulación de islotes pancreáticos (TIP) y células madre mesenquimales (CMM) para el tratamiento de la diabetes tipo 1 (DBT1). Se utilizó la base de datos PubMed para identificar los artículos que detallan las aportaciones de investigaciones en el trasplante de islotes pancreáticos y células madre mesenquimales microencapsulados para restablecer la regulación de la glucemia en pacientes diabéticos.

Abstract Clinical islet transplantation is an alternative treatment for selected patients with type 1 Diabetes. With it has accomplished in certain period of time, insulin independence at least for a year although after that the patient will need another transplant. For this reason, researchers have thought strategies to allow improve the islet transplantation. The aim of this review is focus in different ways to improve the efficacy in microencapsulation system with islet transplantation and mesenchymal stem cells for Diabetes Type 1 treatment. We use PubMed database to identify articles that talk about this treatment to adjust the blood glucose in diabetic type 1 patients.

Alzheimer's disease and type 2 diabetes mellitus: Pathophysiologic and pharmacotherapeutics links.

At present, Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) are two highly prevalent disorders worldwide, especially among elderly individuals. T2DM appears to be associated with cognitive dysfunction, with a higher risk of developing neurocognitive disorders, including AD. These diseases have been observed to share various pathophysiological mechanisms, including alterations in insulin signaling, defects in glucose transporters (GLUTs), and mitochondrial dysfunctions in the brain. Therefore, the aim of this review is to summarize the current knowledge regarding the molecular mechanisms implicated in the association of these pathologies as well as recent therapeutic alternatives. In this context, the hyperphosphorylation of tau and the formation of neurofibrillary tangles have been associated with the dysfunction of the phosphatidylinositol 3-kinase and mitogen-activated protein kinase pathways in the nervous tissues as well as the decrease in the expression of GLUT-1 and GLUT-3 in the different areas of the brain, increase in reactive oxygen species, and production of mitochondrial alterations that occur in T2DM. These findings have contributed to the implementation of overlapping pharmacological interventions based on the use of insulin and antidiabetic drugs, or, more recently, azeliragon, amylin, among others, which have shown possible beneficial effects in diabetic patients diagnosed with AD.

Structural effects driven by rare point mutations in amylin hormone, the type II diabetes-associated peptide.

BACKGROUND: Amylin is a 37-amino-acid peptide hormone co-secreted with insulin, which participates in glucose homeostasis. This hormone is able to aggregate in a ß-sheet conformation and deposit in islet amyloids, a hallmark in type II diabetes. Since amylin is a gene-encoded hormone, this peptide has variants caused by point mutations that can impact its functions. METHODS: Here, we analyzed the structural effects caused by S20G and G33R point mutations which, according to the 1000 Genomes Project, have frequency in East Asian and European populations, respectively. The analyses were performed by means of aggrescan server, SNP functional effect predictors, and molecular dynamics. RESULTS: We found that both mutations have aggregation potential and cause changes in the monomeric forms when compared with wild-type amylin. Furthermore, comparative analyses with pramlintide, an amylin drug analogue, allowed us to infer that second α-helix maintenance may be related to the aggregation potential. CONCLUSIONS: The S20G mutation has been described as pathologically related, which is in agreement with our findings. In addition, our data suggest that the G33R mutation might have a deleterious effect. The data presented here also provide new therapy opportunities, whether for creating more effective drugs for diabetes or implementing specific treatment for patients with these mutations. GENERAL SIGNIFICANCE: Our data could help to better understand the impact of mutations on the wild-type amylin sequence, as a starting point for the evaluation and characterization of other variations. Moreover, these findings could improve the health of patients with type II diabetes.

Melatonin regulates maternal pancreatic remodeling and B-cell function during pregnancy and lactation.

The endocrine pancreas of pregnant rats shows evident plasticity, which allows the morphological structures to return to the nonpregnant state right after delivery. Furthermore, it is well-known the role of melatonin in the maintenance of the endocrine pancreas and its tropism. Studies indicate increasing nocturnal serum concentrations of maternal melatonin during pregnancy in both humans and rodents. The present study investigated the role of melatonin on energy metabolism and in pancreatic function and remodeling during pregnancy and early lactation in rats. The results confirm that the absence of melatonin during pregnancy impairs glucose metabolism. In addition, there is a dysregulation in insulin secretion at various stages of the development of pregnancy and an apparent failure in the glucose-stimulated insulin secretion during the lactation period, evidencing the role of melatonin on the regulation of insulin secretion. This mechanism seems not to be dependent on the antioxidant effect of melatonin and probably dependent on MT2 receptors. We also observed changes in the mechanisms of death and cell proliferation at the end of pregnancy and beginning of lactation, crucial periods for pancreatic remodeling. The present observations strongly suggest that both functionality and remodeling of the endocrine pancreas are impaired in the absence of melatonin and its adequate replacement, mimicking the physiological increase seen during pregnancy, is able to reverse some of the damage observed. Thus, we conclude that pineal melatonin is important to metabolic adaptation to pregnancy and both the functionality of the beta cells and the remodeling of the pancreas during pregnancy and early lactation, ensuring the return to nonpregnancy conditions.