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The dysfunction of pancreatic ß-cells plays a pivotal role in the pathogenesis of type 2 diabetes mellitus (T2DM). Despite numerous studies demonstrating the anti-inflammatory and antioxidant properties of puerarin, the protective effects of puerarin on ß-cells remain poorly understood. Hence, this study aimed to explore the effects of puerarin on ß-cell dysfunction in a hyperglycemic environment via the PINK/Parkin-mediated mitochondrial autophagy pathway. The alterations in cell viability of MIN6 cells exposed to glucose concentrations of 5 mM, 10 mM, 20 mM, and 30 mM for 24 h, 48 h, and 72 h, respectively, were assessed using the CCK-8 assay to optimize the modeling conditions. Subsequently, cellular insulin secretion was measured using enzyme-linked immunosorbent assay (ELISA), apoptosis rate by flow cytometry, mitochondrial membrane potential alteration by JC-1, cellular ROS production by the DCFH-DA fluorescent probe, and fusion of cellular autophagosomes and lysosomes through adenoviral infection analysis. Furthermore, gene and protein expression levels of the PINK/Parkin-mediated mitochondrial autophagy pathway and mitochondrial apoptosis pathway were assessed using real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot, respectively. Results indicated a significant decrease in MIN6 cell viability following 48 h of exposure to 30 mM glucose concentration. Puerarin intervention markedly attenuated ROS production, restored mitochondrial membrane potential, induced PINK/Parkin-mediated mitochondrial autophagy, suppressed activation of the mitochondrial apoptotic pathway, mitigated apoptosis, and enhanced insulin secretion in a high glucose (HG) environment. The findings of this investigation contribute to a deeper understanding of the precise mechanism underlying the protective effects of puerarin on ß-cells and offer a theoretical foundation for advancing puerarin-based therapeutics aimed at ameliorating T2DM.
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BACKGROUND: Pathogenesis of type 2 diabetes mellitus (T2DM) is combined from initial insulin resistance (IR) and subsequent ß-cell dysfunction. Insulin therapy can replace ß-cell function in advanced stages. However excessive insulin therapy increases IR and may expose the patients to risk of cardiovascular disease. We aim to assess ß-cell function and IR in patients with type 2 diabetes on insulin therapy by fasting C-peptide to glucose ratio (FCPGR), and triglyceride glucose (TyG) index respectively to support treatment plans. METHOD: A cross-sectional study was conducted at the Galiawa Diabetes and Endocrinology Teaching Center in Erbil City, Iraq, from June 2023 to January 2024. A convenient sample of 100 patients with T2DM on insulin-based therapy were included after obtaining informed written consent and excluding conditions such as acute illness, uncertain type of diabetes, etc. Each patient was evaluated for anthropometric parameters and current treatment details. Biochemical tests were then carried out to calculate metabolic syndrome (MetS) index score, FCPGR, and TyG index. Finally, patients were divided into four subgroups according to their FCPGR and TyG index and the data were analyzed statistically. RESULT: The data showed those patients with sufficient ß-cell function were 60 (60%), and patients with high TyG index were 95 (95%). There was a significant negative correlation between FCPGR and hemoglobin A1c (HbA1c) (p-value=0.001), while there was a positive correlation between TyG index and HbA1C (p-value=0.001). None of these markers were correlated with BMI (p-value=0.297, and 0.976), duration of T2DM (p-value=0.258, and 0.458), and dose of insulin therapy (p-value=0.901, and 0.477). Patients with sufficient ß-cell function and high TyG index had the lowest HbA1C. CONCLUSION: The study provides valuable insights into the utility of FCPGR and TyG index as biomarkers for ß-cell function and insulin resistance in T2DM patients on insulin therapy. The significant correlation with HbA1C underscores their potential in clinical practice. However, the lack of correlation with BMI, disease duration, and insulin dose suggests that further investigation is needed to fully understand these biomarkers' implications across diverse patient profiles.
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GLP-1 receptor agonists, which were initially intended to treat type 2 diabetes patients, have demonstrated promise as an adjuvant therapy for type 1 diabetes (T1D). These medications can manage T1D by improving ß-cell function, reducing glucose fluctuation, and providing cardioprotective effects. Recent research suggests that boosting cell proliferation and lowering apoptosis can help maintain the bulk of ß-cells. Furthermore, GLP-1 receptor agonists have potent anti-inflammatory characteristics, improving immunological control and lowering systemic inflammation, both of which are critical for reducing autoimmune damage in T1D. Beyond glucose control, these agonists have neuroprotective qualities and aid in weight management. Combining these medications with insulin could significantly change how T1D is managed. The clinical data and biological mechanisms discussed in this review support the potential use of GLP-1 receptor agonists in T1D.
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Diabetes Mellitus Tipo 1 , Receptor del Péptido 1 Similar al Glucagón , Hipoglucemiantes , Humanos , Receptor del Péptido 1 Similar al Glucagón/agonistas , Diabetes Mellitus Tipo 1/tratamiento farmacológico , Diabetes Mellitus Tipo 1/metabolismo , Hipoglucemiantes/uso terapéutico , Hipoglucemiantes/farmacología , Animales , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Insulina/metabolismo , Insulina/uso terapéutico , Agonistas Receptor de Péptidos Similares al GlucagónRESUMEN
The purpose of this review is to examine the current scientific literature regarding the interplay between the exocrine and endocrine pancreas, specifically the role of the exocrine pancreas in the pathogenesis of canine diabetes mellitus. ß-cell death caused by exocrine pancreatic inflammation is thought to be an under-recognised contributor to diabetes mellitus in dogs, with up to 30â¯% of canine diabetic patients with concurrent evidence of pancreatitis at post-mortem examination. Current diagnostics for pancreatitis are imprecise, and treatments for both diseases individually have their own limitations: diabetes through daily insulin injections, which has both welfare and financial implications for the stakeholders, and pancreatitis through treatment of clinical signs, such as analgesia and anti-emetics, rather than targeted treatment of the underlying cause. This review will consider the evidence for exocrine pancreatic inflammation making an active contribution to pancreatic ß-cell loss and insulin-deficiency diabetes in the dog and explore current and potential future diagnostic and treatment avenues to improve outcomes for these patients.
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Diabetes is a complex, multifactorial disease that is caused by a pathological combination of insulin resistance and pancreatic islet dysfunction. Polysaccharides are extensively dispersed in nature and have a very complicated structure with various biological properties. Natural polysaccharides have potentially extraordinary beneficial health effects on managing metabolic diseases such as diabetes, obesity and cardiovascular disease. Thus, a systematic review of the latest research into and possible regulatory mechanisms of natural polysaccharides for type 2 diabetes mellitus treatment is of great significance for a better understanding of their pharmaceutical value. We discuss the regulatory mechanisms of natural polysaccharides for the treatment of diabetes, and especially their role in reshaping dysfunctional gut microbiota. Natural polysaccharides could be developed as new and safe antidiabetic drugs, and detailed mechanistic studies could further clarify the molecular targets of polysaccharides in the treatment of diabetes.
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The pancreas has been considered a non-regenerative organ. ß cells lost in diabetes are not replaced due to the inability of the pancreas to regenerate. However, ample evidence generated in the last few decades using murine models has demonstrated that the pancreas has a remarkable plasticity wherein differentiated cells can change cell fate toward a ß-like cell phenotype. Although this process is observed after using rather artificial stimuli and the conversion efficiency is very limited, these findings have shed some light on novel pathways for ß-cell regeneration. In this chapter, we will summarize the different cellular interconversion processes described to date, the experimental details and molecular regulation of such interconversions, and the genomic technologies that have allowed the identification of potential new ways to generate ß cells.
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Plasticidad de la Célula , Células Secretoras de Insulina , Regeneración , Animales , Células Secretoras de Insulina/fisiología , Células Secretoras de Insulina/citología , Regeneración/fisiología , Humanos , Plasticidad de la Célula/fisiología , Páncreas/fisiología , Páncreas/citología , Diferenciación Celular , RatonesRESUMEN
Aim: Type II diabetes (T2D) stems from insulin resistance, with ß-cell dysfunction as a hallmark in its progression. Studies reveal that ß cells undergo apoptosis or dedifferentiation during T2D development. The transcription factor PAX4 is vital for ß differentiation and survival, thus may be a potential enhancer of ß-cell function in T2D islets. Materials & methods: Human PAX4 cDNA was delivered into T2D human islets with an adenoviral vector, and its effects on ß cells were examined. Results: PAX4 gene delivery significantly improved ß-cell survival, and increased ß-cell composition in the T2D human islets. Basal insulin and glucose-stimulated insulin secretion in PAX4-expressing islets were substantially higher than untreated or control-treated T2D human islets. Conclusion: Introduced PAX4 expression in T2D human islets improves ß-cell function, thus could provide therapeutic benefits for T2D treatment.
Type II diabetes (T2D) results from insulin resistance, with ß-cell dysfunction playing a pivotal role in its progression. Deficits in ß-cell mass and function have been attributed primarily to ß-cell death through apoptosis; however, recent studies suggest ß-cell failure can also arise from ß-cell dedifferentiation that is, ß cells undergo a loss of mature identity, adopting either progenitor-like or glucagon-producing α cell states during T2D development. Therefore, a strategy preventing ß-cell dedifferentiation while promoting its survival is beneficial for T2D treatment. In this study, we explored whether PAX4, a critical transcription factor for ß differentiation and survival, could alleviate ß-cell dysfunction in human islets derived from T2D patients. To accomplish that, human PAX4 cDNA was delivered into human islets isolated from T2D donors by an adenoviral vector-based vector, Ad5.Pax4 and its effects on ß-cell function were evaluated. The results showed PAX4 expression significantly improved ß-cell survival and increased ß-cell composition in the T2D islets. Notably, PAX4-treated T2D islets exhibited significantly higher basal insulin secretion and glucose-stimulated insulin secretion than control-treated islets. The data demonstrate that PAX4 gene delivery into T2D human islets enhances ß-cell mass and function, and thus may offer therapeutic benefits in the treatment of T2D.
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Diabetes Mellitus Tipo 2 , Proteínas de Homeodominio , Células Secretoras de Insulina , Insulina , Factores de Transcripción Paired Box , Humanos , Diabetes Mellitus Tipo 2/terapia , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Factores de Transcripción Paired Box/metabolismo , Factores de Transcripción Paired Box/genética , Células Secretoras de Insulina/metabolismo , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Insulina/metabolismo , Secreción de Insulina , Técnicas de Transferencia de Gen , Supervivencia Celular , Islotes Pancreáticos/metabolismo , Terapia Genética/métodosRESUMEN
The significant advances in the differentiation of human pluripotent stem (hPS) cells into pancreatic endocrine cells, including functional ß-cells, have been based on a detailed understanding of the underlying developmental mechanisms. However, the final differentiation steps, leading from endocrine progenitors to mono-hormonal and mature pancreatic endocrine cells, remain to be fully understood and this is reflected in the remaining shortcomings of the hPS cell-derived islet cells (SC-islet cells), which include a lack of ß-cell maturation and variability among different cell lines. Additional signals and modifications of the final differentiation steps will have to be assessed in a combinatorial manner to address the remaining issues and appropriate reporter lines would be useful in this undertaking. Here we report the generation and functional validation of hPS cell reporter lines that can monitor the generation of INS+ and GCG+ cells and their resolution into mono-hormonal cells (INSeGFP, INSeGFP/GCGmCHERRY) as well as ß-cell maturation (INSeGFP/MAFAmCHERRY) and function (INSGCaMP6). The reporter hPS cell lines maintained strong and widespread expression of pluripotency markers and differentiated efficiently into definitive endoderm and pancreatic progenitor (PP) cells. PP cells from all lines differentiated efficiently into islet cell clusters that robustly expressed the corresponding reporters and contained glucose-responsive, insulin-producing cells. To demonstrate the applicability of these hPS cell reporter lines in a high-content live imaging approach for the identification of optimal differentiation conditions, we adapted our differentiation procedure to generate SC-islet clusters in microwells. This allowed the live confocal imaging of multiple SC-islets for a single condition and, using this approach, we found that the use of the N21 supplement in the last stage of the differentiation increased the number of monohormonal ß-cells without affecting the number of α-cells in the SC-islets. The hPS cell reporter lines and the high-content live imaging approach described here will enable the efficient assessment of multiple conditions for the optimal differentiation and maturation of SC-islets.
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Diferenciación Celular , Genes Reporteros , Células Secretoras de Insulina , Islotes Pancreáticos , Células Madre Pluripotentes , Humanos , Células Secretoras de Insulina/citología , Células Secretoras de Insulina/metabolismo , Islotes Pancreáticos/citología , Islotes Pancreáticos/metabolismo , Células Madre Pluripotentes/citología , Células Madre Pluripotentes/metabolismo , Línea Celular , Insulina/metabolismo , Proteínas Fluorescentes Verdes/metabolismo , Proteínas Fluorescentes Verdes/genéticaRESUMEN
AIMS: To evaluate whether treatment with insulin is advantageous compared with oral anti-diabetic drugs (OAD) for patients newly diagnosed with type 2 diabetes with moderate hyperglycemia. METHODS: Patients newly diagnosed with type 2 diabetes with moderate hyperglycemia were recruited and randomized to receive insulin, metformin or sitagliptin treatment. The oral glucose tolerance test (OGTT) was performed before treatment and 6 months thereafter. The primary outcome was the glycohemoglobin (HbA1c) level change. For the secondary efficacy analysis, the ß-cell function and insulin sensitivity were calculated from the OGTT, as was the proportion of subjects who reached the treatment target (HbA1c level < 7.0 % or < 6.5 %) at 6 months. RESULTS: We randomized 50 patients to the three groups and 32 patients who received the allocated treatment were analyzed. The change of HbA1c level in the insulin, metformin, and sitagliptin groups was - 2.06 ± 1.37 %, -0.43 ± 0.32 %, and - 1.62 ± 0.92 %, respectively. This change was smallest in the metformin group. There was no significant difference in the changes or final HbA1c levels between the insulin and sitagliptin groups. The treat-to-target (HbA1c level < 7.0 %) rates in the insulin, metformin and sitagliptin were 75 %, 50 % and 100 %, respectively. The treat-to-target rates were not significantly different among the three groups. The insulin secretion indices, including the Matsuda index and HOMA-IR, indicated that the groups did not differ after 6 months of therapy. CONCLUSION: A 6-month course of basal insulin therapy did not benefit patients newly diagnosed with diabetes with moderate hyperglycemia in terms of insulin sensitivity or insulin secretion.
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Glucemia , Diabetes Mellitus Tipo 2 , Hemoglobina Glucada , Hiperglucemia , Hipoglucemiantes , Células Secretoras de Insulina , Insulina , Metformina , Fosfato de Sitagliptina , Humanos , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Diabetes Mellitus Tipo 2/sangre , Masculino , Femenino , Persona de Mediana Edad , Hipoglucemiantes/uso terapéutico , Células Secretoras de Insulina/efectos de los fármacos , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/fisiología , Insulina/uso terapéutico , Metformina/uso terapéutico , Fosfato de Sitagliptina/uso terapéutico , Hemoglobina Glucada/metabolismo , Hemoglobina Glucada/análisis , Glucemia/metabolismo , Glucemia/efectos de los fármacos , Glucemia/análisis , Anciano , Control Glucémico , Prueba de Tolerancia a la GlucosaRESUMEN
The present study investigated the associations of serum gamma-glutamyl transferase (GGT), a marker of fatty liver and oxidative stress, and ALT/AST, a marker of fatty liver, with percentage trunk fat and postload glucose, insulin resistance, and ß-cell function in middle-aged Japanese individuals, whose BMI averaged < 23.0 kg/m2. Pancreatic ß-cell function was assessed using the disposition index calculated by a product of the insulinogenic index (IGI) and Matsuda insulin sensitivity index, a biomarker of early-phase glucose-stimulated insulin secretion and whole-body insulin sensitivity, respectively. Multivariate linear regression analyses revealed that the disposition index was associated inversely with GGT independently of percentage trunk fat, homeostasis model assessment insulin resistance (HOMA-IR), a marker of insulin resistance, and Matsuda index. When IGI was included instead of the disposition index, IGI (inversely) and HOMA-IR were associated with GGT independently of percentage trunk fat and Matsuda index. When the area under the glucose concentration curve (AUCg) during an oral glucose tolerance test was included instead of the disposition index, AUCg and HOMA-IR emerged as independent determinants of GGT. ALT/AST was associated with HOMA-IR alone. Results suggest a different pathophysiologic basis between GGT and ALT/AST in predicting diabetic risk in non-obese Japanese.
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Alanina Transaminasa , Resistencia a la Insulina , Secreción de Insulina , Células Secretoras de Insulina , gamma-Glutamiltransferasa , Humanos , gamma-Glutamiltransferasa/sangre , gamma-Glutamiltransferasa/metabolismo , Células Secretoras de Insulina/metabolismo , Masculino , Alanina Transaminasa/sangre , Alanina Transaminasa/metabolismo , Femenino , Persona de Mediana Edad , Japón , Insulina/sangre , Insulina/metabolismo , Adulto , Biomarcadores/sangre , Glucemia/metabolismo , Glucemia/análisis , Prueba de Tolerancia a la Glucosa , Pueblos del Este de AsiaRESUMEN
The relationship of adipose tissue insulin resistance (AT-IR, a product of fasting insulin and free fatty acids) and homeostasis-model assessment-insulin resistance (HOMA-IR) to ß-cell function was studied cross-sectionally in the setting of subtle glucose dysregulation. Associations of AT-IR and HOMA-IR with fasting and post-glucose glycemia and ß-cell function inferred from serum insulin kinetics during a 75 g oral glucose tolerance test were studied in 168 young female Japanese students. ß-cell function was evaluated by disposition index calculated as a product of the insulinogenic index (IGI) and Matsuda index. AT-IR, not HOMA-IR, showed positive associations with post-glucose glycemia and area under the glucose response curve although both indices were associated with fasting glycemia. HOMA-IR, not AT-IR, was associated positively with log IGI whereas both indices were inversely associated with Matsuda index. AT-IR, not HOMA-IR, showed inverse associations with log disposition index. Associations of adipose tissue insulin resistance with ß-cell function (inverse) and glucose excursion in young Japanese women may suggest that lipotoxicity to pancreatic ß-cells for decades may be associated with ß cell dysfunction found in Japanese patients with type 2 diabetes. Positive association of HOMA-IR with insulinogenic index may be associated with compensatory increased insulin secretion.
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Tejido Adiposo , Glucemia , Prueba de Tolerancia a la Glucosa , Resistencia a la Insulina , Células Secretoras de Insulina , Insulina , Humanos , Femenino , Células Secretoras de Insulina/metabolismo , Tejido Adiposo/metabolismo , Glucemia/metabolismo , Adulto Joven , Adulto , Japón , Insulina/sangre , Insulina/metabolismo , Estudios Transversales , Ayuno/sangre , Pueblos del Este de AsiaRESUMEN
CONTEXT: ß-cell dedifferentiation ratio is increased in type 2 diabetes; but its direct link to in vivo ß-cell function in human remains unclear. OBJECTIVE: The present study was designed to investigate whether ß-cell dedifferentiation in situ was closely associated with ß-cell function in vivo and to identify targets crucial for ß-cell dedifferentiation/function in human. METHODS: We acquired HOMA-ß values, calculated the number of hormone-negative endocrine cells and evaluated important markers and novel candidates for ß-cell dedifferentiation/function on paraneoplastic pancreatic tissues from 13 patients with benign pancreatic cystic neoplasm (PCN) or intrapancreatic accessory spleen. RESULTS: Both ß-cell dedifferentiation ratio and dedifferentiation marker (Aldh1a3) were inversely related with in vivo ß-cell function (HOMA-ß) and in situ ß-cell functional markers Glut2 and Ucn3 in human. Moreover, the islets from HOMA-ßlow subjects were manifested as 1) increased ß-cell dedifferentiation ratio, 2) enriched dedifferentiation maker Aldh1a3, and 3) lower expression of Glut2 and Ucn3, compared to those from HOMA-ßhigh subjects. We found that basic leucine zipper transcription factor 2 (Bach2) expression was significantly induced in islets from HOMA-ßlow patients and was positively correlated with the ratio of ß-cell dedifferentiation in human. CONCLUSIONS: Our findings emphasize the contribution of ß-cell dedifferentiation to ß-cell dysfunction in human. The Bach2 induction in ß-cells with higher frequency of dedifferentiation observed in HOMA-ßlow subjects reinforce its distinctive role as a pharmaceutical target of ß-cell dedifferentiation for the treatment of human diabetes.
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Type 1 diabetes (T1D) is a common autoimmune disease in which dysregulated glucose metabolism is a key feature. T1D is both poorly understood and in need of improved therapeutics. Hypoxia is frequently encountered in multiple tissues in T1D patients including the pancreas and sites of diabetic complications. Hypoxia-inducible factor (HIF)-1, a ubiquitous master regulator of the adaptive response to hypoxia, promotes glucose metabolism through transcriptional and non-transcriptional mechanisms and alters disease progression in multiple preclinical T1D models. However, how HIF-1 activation in ß-cells of the pancreas and immune cells (two key cell types in T1D) ultimately affects disease progression remains controversial. We discuss recent advances in our understanding of the role of hypoxia/HIF-1-induced glycolysis in T1D and explore the possible use of drugs targeting this pathway as potential new therapeutics.
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Diabetes Mellitus Tipo 1 , Factor 1 Inducible por Hipoxia , Animales , Humanos , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 1/tratamiento farmacológico , Glucólisis , Factor 1 Inducible por Hipoxia/metabolismo , Células Secretoras de Insulina/metabolismoRESUMEN
PURPOSE: We aimed to investigate the predictive potential of plasma connecting peptide (C-peptide) in differentiating type 1 diabetes (T1D) from type 2 diabetes (T2D) and to inform evidence-based diabetes classification criteria. METHODS: A retrospective review was performed of all the patients with diabetes visiting an outpatient diabetology, endocrinology, general practice and family medicine tertiary health care center between January 2016 and December 2021. FINDINGS: Two hundred twelve individuals with diabetes were included, 85 (44.8%) with T1D and 127 (55.2%) with T2D. Mean (SD) age at diagnosis was 35.9 (15.1) years, and 112 (52.8%) men. Median (interquartile range [IQR]) duration of diabetes was 3.8 (3.0-4.5) years (T1D, 3.9 [3.5-4.6]; T2D, 3.4 [2.4-4.4]; P = 0.001). Body mass index was <18.5 kg/m2 in 5 (2.5%) individuals (T1D, 5; T2D, none), 18.5 to <25 kg/m2 in 57 (28.5%) (T1D, 32; T2D, 25), 25 to <30 kg/m2 in 58 (29%) (T1D, 28; T2D, 30), and >30 kg/m2 in 80 (40.0%) (T1D, 20; T2D, 60). Median (IQR) glycosylated hemoglobin was 7.4% (6.7%-8.5%) (T1D, 8.3% [7.2%-9.9%]; T2D, 7% [6.3%-7.6%]; P = 0.0001). Median (IQR) C-peptide concentration was 0.59 nmol/L (0.01-1.14 nmol/L) (T1D, 0.01 nmol/L [0.003-0.05 nmol/L]; T2D, 1.03 nmol/L [0.70-1.44 nmol/L]; P = 0.0001). C-peptide concentration of ≤0.16 nmol/L showed 92.9% sensitivity, 1-specificity of 2.4%, and AUC of 97.2% (CI, 94.7%-99.6%; P = 0.0001) in differentiating T1D from T2D. IMPLICATIONS: To our knowledge, this is the first study in the Middle East and North Africa region highlighting the role of C-peptide in diabetes classification. The estimated cutoff point for C-peptide concentration (≤0.16 nmol/L) will certainly help in accurately classifying the T1D and will rule out the routine clinical judgmental approaches in the region, especially in those scenarios and periods where it is always difficult to diagnose the diabetes type. Quantifying the cutoff for C-peptide is among the vital strengths of this study that will provide a better treatment plan in diabetes care management. Also, we evaluated concomitant glucose levels to rule out the phenomenon of falsely low C-peptide values in the setting of hypoglycemia or severe glucose toxicity. Based on our findings, C-peptide testing could be included in postulating an evidence-based guideline that differentiates T1D from T2D. Despite this, our study has some limitations, including the selection bias due to the retrospective design and low C-peptide levels could be indicative of low pancreatic reserves due to other causes or long-standing T2D, and quantifying these reasons requires additional resources and time.
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Péptido C , Diabetes Mellitus Tipo 1 , Diabetes Mellitus Tipo 2 , Pacientes Ambulatorios , Humanos , Péptido C/sangre , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/diagnóstico , Masculino , Diabetes Mellitus Tipo 1/sangre , Diabetes Mellitus Tipo 1/diagnóstico , Femenino , Estudios Retrospectivos , Adulto , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Diagnóstico Diferencial , Biomarcadores/sangre , Hemoglobina Glucada/análisis , Hemoglobina Glucada/metabolismo , Adulto JovenRESUMEN
Beta-casomorphins (BCMs) are the bio-active peptides having opioid properties which are formed by the proteolytic digestion of ß-caseins in milk. BCM-7 forms when A1 milk is digested in the small intestine due to a histidine at the 67th position in ß-casein, unlike A2 milk, which has proline at this position and produces BCM-9. BCM-7 has further degraded into BCM-5 by the dipeptidyl peptidase-IV (DPP-IV) enzyme in the intestine. The opioid-like activity of BCM-7 is responsible for eliciting signaling pathways which enable a wide range of physiological effects. The aim of our study was to find out the differential role of BCMs (BCM-7, BCM-9 and BCM-5) on pancreatic ß-cell proliferation, insulin secretion, and opioid peptide binding receptors from ß-cells (RIN-5F cell line) in normal (5.5 mM) and high glucose (27.5 mM) concentrations. Our results showed that BCM-7/9/5 did not affect ß-cell viability, proliferation, and insulin secretion at normal glucose level. However, at higher glucose concentration, BCMs significantly protected ß-cells from glucotoxicity but did not affect the insulin secretion. Interestingly, in the presence of Mu-opioid peptide receptor antagonist CTOP, BCMs did not protect ß-cells from glucotoxicity. The results suggest that BCMs protect ß-cells from glucotoxicity via non-opioid mediated pathways because BCMs did not modulate the gene expression of the mu, kappa and delta opioid peptide receptors.
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Aim: We tested whether skeletal muscle mass is associated with insulin sensitivity, pancreatic ß-cell function, and postglucose glycemia. Methods: Appendicular skeletal muscle mass (ASM) (relative to body size, %ASM) by DXA, surrogate measures of insulin sensitivity, insulin secretion and the disposition index (insulin sensitivity adjusted insulin secretion: a product of the insulinogenic index and Matsuda insulin sensitivity index) inferred from serum insulin kinetics during a 75 g oral glucose tolerance test (OGTT) were evaluated in 168 young and 65 middle-aged women, whose BMI averaged <23.0 kg/m2 and HbA1c ⦠5.5 %. Results: In two groups of women, %ASM was associated negatively with homeostasis model assessment insulin resistance (HOMA-IR) and 2-h insulin (both p < 0.01 or less). In middle-aged women not in young women, %ASM was associated inversely with the Matsuda index (p < 0.001). In middle-aged women only, it also showed a positive association with the disposition index (p = 0.02) and inverse associations with 1-h and 2-h glucose (both p < 0.01) and area under the glucose concentration curve during OGTT (p = 0.006). On multivariate linear regression analyses, 2-h insulin emerged as a determinant of %ASM independently of HOMA-IR in young women (standardized ß: 0.287, p < 0.001, R2 = 0.077). In middle-aged women, the Matsuda index emerged as a determinant of %ASM (standardized ß: 0.476, p < 0.001) independently of HOMA-IR, log ODI and AUCg and explained 21.3 % of %ASM variability. Post-glucose glycemia and AUCg were higher and log ODI was lower in middle-aged women with low compared with high %ASM. Conclusion: Low skeletal muscle mass (relative to body size) was associated with low insulin sensitivity in young and middle-aged Japanese women who were neither obese nor diabetic. Middle-aged women with low muscle mass had low disposition index, an early marker of inadequate pancreatic ß-cell compensation, and hence high glucose excursion. Low skeletal muscle mass may be associated with the development of type 2 diabetes at a much lower BMI in Japanese people.
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Type 2 diabetes (T2D) is a common metabolic disease due to insufficient insulin secretion by pancreatic ß-cells in the context of insulin resistance. Islet molecular pathology reveals a role for protein misfolding in ß-cell dysfunction and loss with islet amyloid derived from islet amyloid polypeptide (IAPP), a protein coexpressed and cosecreted with insulin. The most toxic form of misfolded IAPP is intracellular membrane disruptive toxic oligomers present in ß-cells in T2D and in ß-cells of mice transgenic for human IAPP (hIAPP). Prior work revealed a high degree of overlap of transcriptional changes in islets from T2D and prediabetic 9- to 10-wk-old mice transgenic for hIAPP with most changes being pro-survival adaptations and therefore of limited therapeutic guidance. Here, we investigated islets from hIAPP transgenic mice at an earlier age (6 wk) to screen for potential mediators of hIAPP toxicity that precede predominance of pro-survival signaling. We identified early suppression of cholesterol synthesis and trafficking along with aberrant intra-ß-cell cholesterol and lipid deposits and impaired cholesterol trafficking to cell membranes. These findings align with comparable lipid deposits present in ß-cells in T2D and increased vulnerability to develop T2D in individuals taking medications that suppress cholesterol synthesis.NEW & NOTEWORTHY ß-Cell failure in type 2 diabetes (T2D) is characterized by ß-cell misfolded protein stress due to the formation of toxic oligomers of islet amyloid polypeptide (IAPP). Most transcriptional changes in islets in T2D are pro-survival adaptations consistent with the slow progression of ß-cell loss. In the present study, investigation of the islet transcriptional signatures in a mouse model of T2D expressing human IAPP revealed decreased cholesterol synthesis and trafficking as a plausible early mediator of IAPP toxicity.
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Colesterol , Diabetes Mellitus Tipo 2 , Homeostasis , Células Secretoras de Insulina , Polipéptido Amiloide de los Islotes Pancreáticos , Ratones Transgénicos , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/genética , Animales , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patología , Polipéptido Amiloide de los Islotes Pancreáticos/metabolismo , Colesterol/metabolismo , Ratones , Humanos , Masculino , Transducción de SeñalRESUMEN
In type 1 diabetes (T1D), autoreactive immune cells infiltrate the pancreas and secrete proinflammatory cytokines that initiate cell death in insulin producing islet ß-cells. Protein kinase C δ (PKCδ) plays a role in mediating cytokine-induced ß-cell death; however, the exact mechanisms are not well understood. To address this, we used an inducible ß-cell specific PKCδ KO mouse as well as a small peptide inhibitor of PKCδ. We identified a role for PKCδ in mediating cytokine-induced ß-cell death and have shown that inhibiting PKCδ protects pancreatic ß-cells from cytokine-induced apoptosis in both mouse and human islets. We determined that cytokines induced nuclear translocation and activity of PKCδ and that caspase-3 cleavage of PKCδ may be required for cytokine-mediated islet apoptosis. Further, cytokine activated PKCδ increases activity both of proapoptotic Bax with acute treatment and C-Jun N-terminal kinase with prolonged treatment. Overall, our results suggest that PKCδ mediates cytokine-induced apoptosis via nuclear translocation, cleavage by caspase-3, and upregulation of proapoptotic signaling in pancreatic ß-cells. Combined with the protective effects of PKCδ inhibition with δV1-1, the results of this study will aid in the development of novel therapies to prevent or delay ß-cell death and preserve ß-cell function in T1D.
RESUMEN
OBJECTIVE: Receptor-interacting protein kinase 1 (RIPK1) orchestrates the decision between cell survival and cell death in response to tumor necrosis factor (TNF) and other cytokines. Whereas the scaffolding function of RIPK1 is crucial to prevent TNF-induced apoptosis and necroptosis, its kinase activity is required for necroptosis and partially for apoptosis. Although TNF is a proinflammatory cytokine associated with ß-cell loss in diabetes, the mechanism by which TNF induces ß-cell demise remains unclear. METHODS: Here, we dissected the contribution of RIPK1 scaffold versus kinase functions to ß-cell death regulation using mice lacking RIPK1 specifically in ß-cells (Ripk1ß-KO mice) or expressing a kinase-dead version of RIPK1 (Ripk1D138N mice), respectively. These mice were challenged with streptozotocin, a model of autoimmune diabetes. Moreover, Ripk1ß-KO mice were further challenged with a high-fat diet to induce hyperglycemia. For mechanistic studies, pancreatic islets were subjected to various killing and sensitising agents. RESULTS: Inhibition of RIPK1 kinase activity (Ripk1D138N mice) did not affect the onset and progression of hyperglycemia in a type 1 diabetes model. Moreover, the absence of RIPK1 expression in ß-cells did not affect normoglycemia under basal conditions or hyperglycemia under diabetic challenges. Ex vivo, primary pancreatic islets are not sensitised to TNF-induced apoptosis and necroptosis in the absence of RIPK1. Intriguingly, we found that pancreatic islets display high levels of the antiapoptotic cellular FLICE-inhibitory protein (cFLIP) and low levels of apoptosis (Caspase-8) and necroptosis (RIPK3) components. Cycloheximide treatment, which led to a reduction in cFLIP levels, rendered primary islets sensitive to TNF-induced cell death which was fully blocked by caspase inhibition. CONCLUSIONS: Unlike in many other cell types (e.g., epithelial, and immune), RIPK1 is not required for cell death regulation in ß-cells under physiological conditions or diabetic challenges. Moreover, in vivo and in vitro evidence suggest that pancreatic ß-cells do not undergo necroptosis but mainly caspase-dependent death in response to TNF. Last, our results show that ß-cells have a distinct mode of regulation of TNF-cytotoxicity that is independent of RIPK1 and that may be highly dependent on cFLIP.