The Beta Cell in Type 2 Diabetes

Inhibition of glycogen synthase kinase-3 enhances NRF2 protein stability, nuclear localisation and target gene transcription in pancreatic beta cells

Accumulation of reactive oxygen species (i.e., oxidative stress) is a leading cause of beta cell dysfunction and apoptosis in diabetes. NRF2 (NF-E2 p45-related factor-2) regulates the adaptation to oxidative stress, and its activity is negatively regulated by the redox-sensitive CUL3 (cullin-3) ubiquitin ligase substrate adaptor KEAP1 (Kelch-like ECH-associated protein-1). Additionally, NRF2 is repressed by the insulin-regulated Glycogen Synthase Kinase-3 (GSK3). We have demonstrated that phosphorylation of NRF2 by GSK3 enhances β-TrCP (beta-transducin repeat-containing protein) binding and ubiquitylation by CUL1 (cullin-1), resulting in increased proteasomal degradation of NRF2. Thus, we hypothesise that inhibition of GSK3 activity or β-TrCP binding upregulates NRF2 and so protects beta cells against oxidative stress. We have found that treating the pancreatic beta cell line INS-1 832/13 with the KEAP1 inhibitor TBE31 significantly enhanced NRF2 protein levels. The presence of the GSK3 inhibitor CT99021 or the β-TrCP-NRF2 protein-protein interaction inhibitor PHAR, along with TBE31, resulted in prolonged NRF2 stability and enhanced nuclear localisation (P < 0.05). TBE31-mediated induction of NRF2-target genes encoding NAD(P)H quinone oxidoreductase 1 (Nqo1), glutamate-cysteine ligase modifier (Gclm) subunit and heme oxygenase (Hmox1) was significantly enhanced by the presence of CT99021 or PHAR (P < 0.05) in both INS-1 832/13 and in isolated mouse islets. Identical results were obtained using structurally distinct GSK3 inhibitors and inhibition of KEAP1 with sulforaphane. In summary, we demonstrate that GSK3 and β-TrCP/CUL1 regulate the proteasomal degradation of NRF2, enhancing the impact of KEAP1 regulation, and so contributes to the redox status of pancreatic beta cells. Inhibition of GSK3, or β-TrCP/CUL1 binding to NRF2 may represent a strategy to protect beta cells from oxidative stress.

High-Throughput Methods for the Discovery of Small Molecule Modulators of Pancreatic Beta-Cell Function and Regeneration

The progression of type II diabetes (T2D) is characterized by a complex and highly variable loss of beta-cell mass, resulting in impaired insulin secretion. Many T2D drug discovery efforts aimed at discovering molecules that can protect or restore beta-cell mass and function have been developed using limited beta-cell lines and primary rodent/human pancreatic islets. Various high-throughput screening methods have been used in the context of drug discovery, including luciferase-based reporter assays, glucose-stimulated insulin secretion, and high-content screening. In this context, a cornerstone of small molecule discovery has been the use of immortalized rodent beta-cell lines. Although insightful, this usage has led to a more comprehensive understanding of rodent beta-cell proliferation pathways rather than their human counterparts. Advantages gained in enhanced physiological relevance are offered by three-dimensional (3D) primary islets and pseudoislets in contrast to monolayer cultures, but these approaches have been limited to use in low-throughput experiments. Emerging methods, such as high-throughput 3D islet imaging coupled with machine learning, aim to increase the feasibility of integrating 3D microtissue structures into high-throughput screening. This review explores the current methods used in high-throughput screening for small molecule modulators of beta-cell mass and function, a potentially pivotal strategy for diabetes drug discovery.

Elucidation of the anti-β-cell dedifferentiation mechanism of a modified Da Chaihu Decoction by an integrative approach of network pharmacology and experimental verification

ETHNOPHARMACOLOGICAL RELEVANCE

Modified Da Chaihu decoction (MDCH) is a traditional Chinese herbal prescription that has been used in the clinic to treat type 2 diabetes (T2D). Previous studies have confirmed that MDCH improves glycemic and lipid metabolism, enhances pancreatic function, and alleviates insulin resistance in patients with T2D and diabetic rats. Evidence has demonstrated that MDCH protects pancreatic β cells via regulating the gene expression of sirtuin 1 (SIRT1) and forkhead box protein O1 (FOXO1). However, the detailed mechanism remains unclear.

AIM OF THE STUDY

Dedifferentiation of pancreatic β cells mediated by FOXO1 has been recognized as the main pathogenesis of T2D. This study aims to investigate the therapeutic effects of MDCH on T2D in vitro and in vivo to elucidate the potential molecular mechanisms.

MATERIALS AND METHODS

To predict the key targets of MDCH in treating T2D, network pharmacology methods were used. A T2D model was induced in diet-induced obese (DIO) C57BL/6 mice with a single intraperitoneal injection of streptozotocin. Glucose metabolism indicators (oral glucose tolerance test, insulin tolerance test), lipid metabolism indicators (total cholesterol, triglyceride, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol), inflammatory factors (C-reactive protein, interleukin 6, tumor necrosis factor alpha), oxidative stress indicators (total antioxidant capacity, superoxide dismutase, malondialdehyde), and hematoxylin and eosin staining were analyzed to evaluate the therapeutic effect of MDCH on T2D. Immunofluorescence staining and quantification of FOXO1, pancreatic and duodenal homeobox 1 (PDX1), NK6 homeobox 1 (NKX6.1), octamer-binding protein 4 (OCT4), neurogenin 3 (Ngn3), insulin, and SIRT1, and Western blot analysis of insulin, SIRT1, and FOXO1 were performed to investigate the mechanism by which MDCH inhibited pancreatic β-cell dedifferentiation.

RESULTS

The chemical ingredients identified in MDCH were predicted to be important for signaling pathways related to lipid metabolism and insulin resistance, including lipids in atherosclerosis, the advanced glycation end product receptor of the advanced glycation end product signaling pathway, and the FOXO signaling pathway. Experimental studies showed that MDCH improved glucose and lipid metabolism in T2D mice, alleviated inflammation and oxidative stress damage, and reduced pancreatic pathological damage. Furthermore, MDCH upregulated the expression levels of SIRT1, FOXO1, PDX1, and NKX6.1, while downregulating the expression levels of OCT4 and Ngn3, which indicated that MDCH inhibited pancreatic dedifferentiation of β cells.

CONCLUSIONS

MDCH has therapeutic effects on T2D, through regulating the SIRT1/FOXO1 signaling pathway to inhibit pancreatic β-cell dedifferentiation, which has not been reported previously.

Loss of mitogen-activated protein kinase phosphate-5 aggravates islet dysfunction in mice with type 1 and type 2 diabetes

Impaired functionality and loss of islet β-cells are the primary abnormalities underlying the pathogenesis of both type 1 and 2 diabetes (T1DM and T2DM). However, specific therapeutic and preventive mechanisms underlying these conditions remain unclear. Mitogen-activated protein kinase phosphatase-5 (MKP-5) has been implicated in carcinogenesis, lipid metabolism regulation, and immune cell activation. In a previous study, we demonstrated the involvement of exogenous MKP-5 in the regulation of obesity-induced T2DM. However, the role of endogenous MKP-5 in the T1DM and T2DM processes is unclear. Thus, mice with MKP-5 knockout (KO) were generated and used to establish mouse models of both T1DM and T2DM. Our results showed that MKP-5 KO exacerbated diabetes-related symptoms in mice with both T1DM and T2DM. Given that most phenotypic studies on islet dysfunction have focused on mice with T2DM rather than T1DM, we specifically aimed to investigate the role of endoplasmic reticulum stress (ERS) and autophagy in T2DM KO islets. To accomplish this, we performed RNA sequence analysis to gain comprehensive insight into the molecular mechanisms associated with ERS and autophagy in T2DM KO islets. The results showed that the islets from mice with MKP-5 KO triggered 5' adenosine monophosphate-activated protein kinase (AMPK)-mediated autophagy inhibition and glucose-regulated protein 78 (GRP-78)-dominated ERS. Hence, we concluded that the autophagy impairment, resulting in islet dysfunction in mice with MKP-5 KO, is mediated through GRP-78 involvement. These findings provide valuable insights into the molecular pathogenesis of diabetes and highlight the significant role of MKP-5. Moreover, this knowledge holds promise for novel therapeutic strategies targeting MKP-5 for diabetes management.

Emerging therapeutic options in the management of diabetes: recent trends, challenges and future directions

Diabetes is a serious health issue that causes a progressive dysregulation of carbohydrate metabolism due to insufficient insulin hormone, leading to consistently high blood glucose levels. According to the epidemiological data, the prevalence of diabetes has been increasing globally, affecting millions of individuals. It is a long-term condition that increases the risk of various diseases caused by damage to small and large blood vessels. There are two main subtypes of diabetes: type 1 and type 2, with type 2 being the most prevalent. Genetic and molecular studies have identified several genetic variants and metabolic pathways that contribute to the development and progression of diabetes. Current treatments include gene therapy, stem cell therapy, statin therapy, and other drugs. Moreover, recent advancements in therapeutics have also focused on developing novel drugs targeting these pathways, including incretin mimetics, SGLT2 inhibitors, and GLP-1 receptor agonists, which have shown promising results in improving glycemic control and reducing the risk of complications. However, these treatments are often expensive, inaccessible to patients in underdeveloped countries, and can have severe side effects. Peptides, such as glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), are being explored as a potential therapy for diabetes. These peptides are postprandial glucose-dependent pancreatic beta-cell insulin secretagogues and have received much attention as a possible treatment option. Despite these advances, diabetes remains a major health challenge, and further research is needed to develop effective treatments and prevent its complications. This review covers various aspects of diabetes, including epidemiology, genetic and molecular basis, and recent advancements in therapeutics including herbal and synthetic peptides.

The role of heat shock proteins (HSPs) in type 2 diabetes mellitus pathophysiology

Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by sustained hyperglycemia caused by impaired insulin signaling and secretion. Metabolic stress, caused by an inappropriate diet, is one of the major hallmarks provoking inflammation, endoplasmic reticulum (ER) stress, and mitochondrial dysfunction. Heat shock proteins (HSPs) are a group of highly conserved proteins that have a crucial role in chaperoning damaged and misfolded proteins to avoid disruption of cellular homeostasis under stress conditions. To do this, HSPs interact with diverse intra-and extracellular pathways among which are the insulin signaling, insulin secretion, and apoptosis pathways. Therefore, HSP dysfunction, e.g. HSP70, may lead to disruption of the pathways responsible for insulin secretion and uptake. Consistently, the altered expression of other HSPs and genetic polymorphisms in HSP-producing genes in diabetic subjects has made HSPs hot research in T2DM. This paper provides a comprehensive overview of the role of different HSPs in T2DM pathogenesis, affected cellular pathways, and the potential therapeutic strategies targeting HSPs in T2DM.

Probiotic for Pancreatic β-Cell Function in Type 2 Diabetes: A Randomized, Double-Blinded, Placebo-Controlled Clinical Trial

INTRODUCTION

Many clinical studies have proved the effectiveness of probiotics in metabolic disorders associated with insulin resistance. However, the impact of probiotic therapy on pancreatic β-cell function is ambiguous. The influence of probiotic supplementation vs. placebo on β-cell function in people with type 2 diabetes (T2D) was assessed in a double-blind, single-center, randomized, placebo-controlled trial (RCT).

METHODS

Sixty-eight patients with T2D were selected for participation in the RCT. Patients were randomly allocated to consumption of live multistrain probiotics or a placebo for 8 weeks, administered as a sachet formulation in double-blind treatment. The primary main outcome was the assessment of β-cell function as change in C-peptide and HOMA-β (homeostasis model assessment-estimated β-cell function), which was calculated using the HOMA2 calculator (Diabetes Trials Unit, University of Oxford). Secondary outcomes were the changes in glycemic control-related parameters, anthropomorphic variables, and cytokines levels. Analysis of covariance was used to assess the difference between groups.

RESULTS

Supplementation with live multiprobiotic was associated with slight significant improvement of β-cell function (HOMA-β increased from 32.48 ± 13.12 to 45.71 ± 25.18; p = 0.003) and reduction of fasting glucose level (13.03 ± 3.46 vs 10.66 ± 2.63 mmol/L and 234.63 ± 62.36 vs 192.07 ± 47.46 mg/dL; p < 0.001) and HbA1c (8.86 ± 1.28 vs 8.48 ± 1.22; p = 0.043) as compared to placebo. Probiotic therapy significantly affects chronic systemic inflammation in people with T2D by reducing pro-inflammatory cytokine levels.

CONCLUSIONS

Probiotic therapies modestly improved β-cell function in patients with T2D. Modulating the gut microbiota represents a new diabetes treatment and should be tested in more extensive studies.

TRIAL REGISTRATION

NCT05765292.

Enteroviral infections are not associated with type 2 diabetes

Introduction

For more than a century, enteroviral infections have been associated with autoimmunity and type 1 diabetes (T1D). Uncontrolled viral response pathways repeatedly presented during childhood highly correlate with autoimmunity and T1D. Virus responses evoke chemokines and cytokines, the "cytokine storm" circulating through the body and attack cells especially vulnerable to inflammatory destruction. Intra-islet inflammation is a major trigger of β-cell failure in both T1D and T2D. The genetic contribution of islet inflammation pathways is apparent in T1D, with several mutations in the interferon system. In contrast, in T2D, gene mutations are related to glucose homeostasis in β cells and insulin-target tissue and rarely within viral response pathways. Therefore, the current study evaluated whether enteroviral RNA can be found in the pancreas from organ donors with T2D and its association with disease progression.

Methods

Pancreases from well-characterized 29 organ donors with T2D and 15 age- and BMI-matched controls were obtained from the network for pancreatic organ donors with diabetes and were analyzed in duplicates. Single-molecule fluorescence in-situ hybridization analyses were performed using three probe sets to detect positive-strand enteroviral RNA; pancreas sections were co-stained by classical immunostaining for insulin and CD45.

Results

There was no difference in the presence or localization of enteroviral RNA in control nondiabetic and T2D pancreases; viral infiltration showed large heterogeneity in both groups ranging from 0 to 94 virus+ cells scattered throughout the pancreas, most of them in the exocrine pancreas. Very rarely, a single virus+ cell was found within islets or co-stained with CD45+ immune cells. Only one single T2D donor presented an exceptionally high number of viruses, similarly as seen previously in T1D, which correlated with a highly reduced number of β cells.

Discussion

No association of enteroviral infection in the pancreas and T2D diabetes could be found. Despite great similarities in inflammatory markers in islets in T1D and T2D, long-term enteroviral infiltration is a distinct pathological feature of T1D-associated autoimmunity and in T1D pancreases.

Association of Subclinical Hypothyroidism with Type 2 Diabetes Mellitus in Qatar: A Cross-Sectional Study

Purpose

The relationship between subclinical hypothyroidism and type 2 diabetes mellitus (T2DM) in Qatar is under-studied, despite the high prevalence of diabetes in the region. This study evaluates the potential association between subclinical hypothyroidism and T2DM in Qatar.

Patients and Methods

A cross-sectional study used participants with and without T2DM from the Qatar Biobank (QBB). Logistic regression analysis was used to assess the association between subclinical hypothyroidism and T2DM, with multivariable logistic regression used to adjust for potential confounders.

Results

The study found that subclinical hypothyroidism was significantly associated with a 2.82 increase in the odds of having T2DM (OR=2.82, 95% CI (1.13, 7.02), p=0.026) after adjusting for potential confounders. The proportion of subclinical hypothyroidism among individuals with T2DM in Qatar was 4.6%, significantly higher than in those without T2DM (2.8%, p=0.18).

Conclusion

This study demonstrates a significant association between subclinical hypothyroidism and T2DM in Qatar. Further research is required to investigate the directionality of this association and its clinical implications.

Endothelium dysfunction and thrombosis in COVID-19 with type 2 diabetes

SARS-CoV-2 can directly or indirectly damage endothelial cells. Endothelial injury, especially phosphatidylserine (PS) exposure on the outer membrane of cells, can more easily promote thrombosis. Type 2 diabetes(T2D) patients were more susceptible to COVID-19, they had more severe symptoms, higher risk of thrombotic complications, and longer duration of post-COVID-19 sequelae. This review provided a detailed overview of the mechanisms underlying endothelial dysfunction in T2D patients with COVID-19 (including long COVID), which may be influenced by hyperglycemia, hypoxia, and pro-inflammatory environments. The mechanisms of thrombosis in T2D patients with COVID-19 are also explored, particularly the effects of increased numbers of PS-exposing particles, blood cells, and endothelial cells on hypercoagulability. Given the high risk of thrombosis in T2D patients with COVID-19, early antithrombotic therapy can both minimize the impact of the disease on patients and maximize the chances of improvement, thereby alleviating patient suffering. We provided detailed guidance on antithrombotic drugs and dosages for mild, moderate, and severe patients, emphasizing that the optimal timing of thromboprophylaxis is a critical factor in influencing prognosis. Considering the potential interactions between antidiabetic, anticoagulant, and antiviral drugs, we proposed practical and comprehensive management recommendations to supplement the incomplete efficacy of vaccines in the diabetic population, reduce the incidence of post-COVID-19 sequelae, and improve patient quality of life.

Application of fluorescence lifetime imaging microscopy to monitor glucose metabolism in pancreatic islets in vivo

Glucose stimulated insulin secretion is mediated by glucose metabolism via oxidative phosphorylation generating ATP that triggers membrane depolarization and exocytosis of insulin. In stressed beta cells, glucose metabolism is remodeled, with enhanced glycolysis uncoupled from oxidative phosphorylation, resulting in the impaired glucose-mediated insulin secretion characteristic of diabetes. Relative changes in glycolysis and oxidative phosphorylation can be monitored in living cells using the 3-component fitting approach of fluorescence lifetime imaging microscopy (FLIM). We engrafted pancreatic islets onto the iris to permit in vivo FLIM monitoring of the trajectory of glucose metabolism. The results show increased oxidative phosphorylation of islet cells (∼90% beta cells) in response to hyperglycemia; in contrast red blood cells traversing the islets maintained exclusive glycolysis as expected in the absence of mitochondria.

Study on the therapeutic effect and mechanism of Tangningtongluo Tablet on diabetic mice

AIMS

To investigate the therapeutic effects of Tangningtongluo Tablet on diabetic mice and its mechanism. This study was established the scientific basis for the clinical application of Tangningtongluo Tablet in the treatment of diabetes mellitus and provided data supporting the transformation of Tangningtongluo Tablet from an in-hospital preparation to a new Chinese medicine.

METHODS

In this study, a diabetic mouse model was established by high-glucose and high-fat diet feeding in combination with STZ injection for 4 weeks. Glucose metabolism, lipid metabolism, liver histomorphological changes and liver function related indexes were detected, pancreatic histomorphological changes and insulin resistance related indexes were observed, and the expression of pathway related proteins and inflammatory factors were examined.

RESULTS

Glycemia and glycated hemoglobin were reduced in diabetic mice after the treatment of Tangningtongluo Tablet, and glucose tolerance and lipid results were modified. The insulin resistance status of the mice was diminished and tissue damage to the pancreas and liver was repaired. Expression of ERS/NF-κB related pathway proteins was reduced in liver tissues, and inflammatory factors such as TNF-α, IL-6 and IL-1β were reduced in serum.

CONCLUSIONS

Tangningtongluo Tablet could reduce blood glucose in diabetic mice, regulate the disorder of lipid metabolism, enhance insulin sensitivity, improve insulin resistance, repair pancreatic tissue damage and protect mouse liver in diabetic mice. The mechanism of action might be related to the regulation of ERS/NF-κB signaling pathway and the reduction of TNF-α, IL-6 and IL-1β production.

Protection of pancreatic islets from oxidative cell death by a peripherally-active morphinan with increased drug safety

OBJECTIVE

Dextromethorphan (DXM) is a commonly used antitussive medication with positive effects in people with type 2 diabetes mellitus, since it increases glucose tolerance and protects pancreatic islets from cell death. However, its use as an antidiabetic medication is limited due to its central nervous side effects and potential use as a recreational drug. Therefore, we recently modified DXM chemically to reduce its blood-brain barrier (BBB) penetration and central side effects. However, our best compound interacted with the cardiac potassium channel hERG (human ether-à-go-go-related gene product) and the μ-opioid receptor (MOR). Thus, the goal of this study was to reduce the interaction of our compound with these targets, while maintaining its beneficial properties.

METHODS

Receptor and channel binding assays were conducted to evaluate the drug safety of our DXM derivative. Pancreatic islets were used to investigate the effect of the compound on insulin secretion and islet cell survival. Via liquor collection from the brain and a behavioral assay, we analyzed the BBB permeability. By performing intraperitoneal and oral glucose tolerance tests as well as pharmacokinetic analyses, the antidiabetic potential and elimination half-life were investigated, respectively. To analyze the islet cell-protective effect, we used fluorescence microscopy as well as flow cytometric analyses.

RESULTS

Here, we report the design and synthesis of an optimized, orally available BBB-impermeable DXM derivative with lesser binding to hERG and MOR than previous ones. We also show that the new compound substantially enhances glucose-stimulated insulin secretion (GSIS) from mouse and human islets and glucose tolerance in mice as well as protects pancreatic islets from cell death induced by reactive oxygen species and that it amplifies the effects of tirzepatide on GSIS and islet cell viability.

CONCLUSIONS

We succeeded to design and synthesize a novel morphinan derivative that is BBB-impermeable, glucose-lowering and islet cell-protective and has good drug safety despite its morphinan and imidazole structures.

Noncanonical Regulation of cAMP-Dependent Insulin Secretion and Its Implications in Type 2 Diabetes

Impaired glucose tolerance (IGT) and β-cell dysfunction in insulin resistance associated with obesity lead to type 2 diabetes (T2D). Glucose-stimulated insulin secretion (GSIS) from β-cells occurs via a canonical pathway that involves glucose metabolism, ATP generation, inactivation of K ATP channels, plasma membrane depolarization, and increases in cytosolic concentrations of [Ca 2+ ] c . However, optimal insulin secretion requires amplification of GSIS by increases in cyclic adenosine monophosphate (cAMP) signaling. The cAMP effectors protein kinase A (PKA) and exchange factor activated by cyclic-AMP (Epac) regulate membrane depolarization, gene expression, and trafficking and fusion of insulin granules to the plasma membrane for amplifying GSIS. The widely recognized lipid signaling generated within β-cells by the β-isoform of Ca 2+ -independent phospholipase A 2 enzyme (iPLA 2 β) participates in cAMP-stimulated insulin secretion (cSIS). Recent work has identified the role of a G-protein coupled receptor (GPCR) activated signaling by the complement 1q like-3 (C1ql3) secreted protein in inhibiting cSIS. In the IGT state, cSIS is attenuated, and the β-cell function is reduced. Interestingly, while β-cell-specific deletion of iPLA 2 β reduces cAMP-mediated amplification of GSIS, the loss of iPLA 2 β in macrophages (MØ) confers protection against the development of glucose intolerance associated with diet-induced obesity (DIO). In this article, we discuss canonical (glucose and cAMP) and novel noncanonical (iPLA 2 β and C1ql3) pathways and how they may affect β-cell (dys)function in the context of impaired glucose intolerance associated with obesity and T2D. In conclusion, we provide a perspective that in IGT states, targeting noncanonical pathways along with canonical pathways could be a more comprehensive approach for restoring β-cell function in T2D. © 2023 American Physiological Society. Compr Physiol 13:5023-5049, 2023.

Zhx2 maintains islet β-cell mass and function by transcriptionally regulating Pax6

Emerging evidence shows that pancreatic β-cell function and quality are key determinants in the progression of type 2 diabetes (T2D). The transcription factor zinc finger homeobox 2 (Zhx2) is involved in proliferation and development of multiple cells. However, the exact role of Zhx2 in β-cells and T2D remains completely unknown. Here, we report that Zhx2 orchestrates β-cell mass and function by regulating paired box protein pax-6 (Pax6). We found that β-cell-specific knockout Zhx2 (Zhx2BKO) mice showed a decrease in β-cell proliferation and glucose homeostasis. Under prediabetic and diabetic conditions, we discovered glucose intolerance in both Zhx2BKO-HFD mice and Zhx2BKO-db/db mice, with reduced β-cell mass and insulin secretion. Mechanistically, we demonstrated that Zhx2 targeted the Pax6 promoter region (-1740∼-1563; -862∼-559; -251∼+75), enhanced promoter activity. Overall, Zhx2 maintains β-cell function by transcriptionally regulating Pax6, which provides a therapeutic target for diabetes intervention.

Periodontitis as a promoting factor of T2D: current evidence and mechanisms

Periodontitis is an infectious disease caused by an imbalance between the local microbiota and host immune response. Epidemiologically, periodontitis is closely related to the occurrence, development, and poor prognosis of T2D and is recognized as a potential risk factor for T2D. In recent years, increasing attention has been given to the role of the virulence factors produced by disorders of the subgingival microbiota in the pathological mechanism of T2D, including islet β-cell dysfunction and insulin resistance (IR). However, the related mechanisms have not been well summarized. This review highlights periodontitis-derived virulence factors, reviews how these stimuli directly or indirectly regulate islet β-cell dysfunction. The mechanisms by which IR is induced in insulin-targeting tissues (the liver, visceral adipose tissue, and skeletal muscle) are explained, clarifying the influence of periodontitis on the occurrence and development of T2D. In addition, the positive effects of periodontal therapy on T2D are overviewed. Finally, the limitations and prospects of the current research are discussed. In summary, periodontitis is worthy of attention as a promoting factor of T2D. Understanding on the effect of disseminated periodontitis-derived virulence factors on the T2D-related tissues and cells may provide new treatment options for reducing the risk of T2D associated with periodontitis.

Pecans and Its Polyphenols Prevent Obesity, Hepatic Steatosis and Diabetes by Reducing Dysbiosis, Inflammation, and Increasing Energy Expenditure in Mice Fed a High-Fat Diet

Pecans (Carya illinoinensis) are considered a functional food due to the high content of polyunsaturated fatty acids, dietary fiber and polyphenols. To determine the effect of whole pecans (WP) or a pecan polyphenol (PP) extract on the development of metabolic abnormalities in mice fed a high-fat (HF) diet, we fed C57BL/6 mice with a Control diet (7% fat), HF diet (23% fat), HF containing 30% WP or an HF diet supplemented with 3.6 or 6 mg/g of PP for 18 weeks. Supplementation of an HF diet with WP or PP reduced fat mass, serum cholesterol, insulin and HOMA-IR by 44, 40, 74 and 91%, respectively, compared to the HF diet. They also enhanced glucose tolerance by 37%, prevented pancreatic islet hypertrophy, and increased oxygen consumption by 27% compared to the HF diet. These beneficial effects were associated with increased thermogenic activity in brown adipose tissue, mitochondrial activity and AMPK activation in skeletal muscle, reduced hypertrophy and macrophage infiltration of subcutaneous and visceral adipocytes, reduced hepatic lipid content and enhanced metabolic signaling. Moreover, the microbial diversity of mice fed WP or PP was higher than those fed HF, and associated with lower circulating lipopolysaccharides (~83-95%). Additionally, a 4-week intervention study with the HF 6PP diet reduced the metabolic abnormalities of obese mice. The present study demonstrates that WP or a PP extract prevented obesity, liver steatosis and diabetes by reducing dysbiosis, inflammation, and increasing mitochondrial content and energy expenditure. Pecan polyphenols were mainly condensed tannin and ellagic acid derivatives including ellagitannins as determined by LC-MS. Herein we also propose a model for the progression of the HF diet-mediated metabolic disorder based on early and late events, and the possible molecular targets of WP and PP extract in preventive and intervention strategies. The body surface area normalization equation gave a conversion equivalent to a daily human intake dose of 2101-3502 mg phenolics that can be obtained from 110-183 g pecan kernels/day (22-38 whole pecans) or 21.6-36 g defatted pecan flour/day for an average person of 60 kg. This work lays the groundwork for future clinical studies.

Glucolipotoxic Stress-Induced Mig6 Desensitizes EGFR Signaling and Promotes Pancreatic Beta Cell Death

A loss of functional beta cell mass is a final etiological event in the development of frank type 2 diabetes (T2D). To preserve or expand beta cells and therefore treat/prevent T2D, growth factors have been considered therapeutically but have largely failed to achieve robust clinical success. The molecular mechanisms preventing the activation of mitogenic signaling pathways from maintaining functional beta cell mass during the development of T2D remain unknown. We speculated that endogenous negative effectors of mitogenic signaling cascades impede beta cell survival/expansion. Thus, we tested the hypothesis that a stress-inducible epidermal growth factor receptor (EGFR) inhibitor, mitogen-inducible gene 6 (Mig6), regulates beta cell fate in a T2D milieu. To this end, we determined that: (1) glucolipotoxicity (GLT) induces Mig6, thereby blunting EGFR signaling cascades, and (2) Mig6 mediates molecular events regulating beta cell survival/death. We discovered that GLT impairs EGFR activation, and Mig6 is elevated in human islets from T2D donors as well as GLT-treated rodent islets and 832/13 INS-1 beta cells. Mig6 is essential for GLT-induced EGFR desensitization, as Mig6 suppression rescued the GLT-impaired EGFR and ERK1/2 activation. Further, Mig6 mediated EGFR but not insulin-like growth factor-1 receptor nor hepatocyte growth factor receptor activity in beta cells. Finally, we identified that elevated Mig6 augmented beta cell apoptosis, as Mig6 suppression reduced apoptosis during GLT. In conclusion, we established that T2D and GLT induce Mig6 in beta cells; the elevated Mig6 desensitizes EGFR signaling and induces beta cell death, suggesting Mig6 could be a novel therapeutic target for T2D.

Memantine mitigates ROS/TXNIP/NLRP3 signaling and protects against mouse diabetic retinopathy: Histopathologic, ultrastructural and bioinformatic studies

Diabetic retinopathy (DRET) triggers vision loss in adults, however, little therapeutic options are existing. Memantine is an anti-Alzheimer drug that antagonizes the activity of glutamate at N-methyl-D-aspartate (NMDA) receptors. Glutamate and thioredoxin-interacting protein (TXNIP) are known to be overexpressed in diabetic retinas and can produce activation of NOD-like receptor protein 3 (NLRP3) with subsequent secretion of interlukin-1β. This study repurposed memantine for its neuroprotective effect in experimental DRET and tested its impact on ROS/TXNIP/NLRP3. In addition, KEGG pathway database and STRING database identified the protein-protein interaction between glutamate receptors and TXNIP/NLRP3. Male Swiss albino mice received alloxan (180 mg/kg) to induce DRET. After 9 weeks, we divided the mice into groups: (a) saline, (ii) DRET, (iii and iv) DRET + oral memantine (5 or 10 mg per kg) for 28 days. Then, mice were euthanized, and eyeballs were removed. Retinal samples were utilized for biochemical, histopathological, and electron microscopy studies. Retinal levels of glutamate, TXNIP, NLRP3 and interlukin-1β were estimated using ELISA technique as well as retinal malondialdehyde. Histopathological and ultrastructural examination demonstrated that oral memantine attenuated vacuolization and restored normal retinal cell layers. Moreover, memantine reduced TXNIP, NLRP3, interleukin-1β and MDA concentrations. These results provide evidence demonstrating memantine' efficacy in alleviating DRET via suppressing reactive oxygen species/TXNIP/NLRP3 signaling cascade. Therefore, memantine might serve as a potential therapy for retinopathy after adequate clinical research.

SnRNA-Seq of Pancreas Revealed the Dysfunction of Endocrine and Exocrine Cells in Transgenic Pigs with Prediabetes

Diabetes poses a significant threat to human health. Exocrine pancreatic dysfunction is related to diabetes, but the exact mechanism is not fully understood. This study aimed to describe the pathological phenotype and pathological mechanisms of the pancreas of transgenic pigs (PIGinH11) that was constructed in our laboratory and to compare it with humans. We established diabetes-susceptible transgenic pigs and subjected them to high-fat and high-sucrose dietary interventions. The damage to the pancreatic endocrine and exocrine was evaluated using histopathology and the involved molecular mechanisms were analyzed using single-nucleus RNA-sequencing (SnRNA-seq). Compared to wild-type (WT) pigs, PIGinH11 pigs showed similar pathological manifestations to type 2 diabetes patients, such as insulin deficiency, fatty deposition, inflammatory infiltration, fibrosis tissue necrosis, double positive cells, endoplasmic reticulum (ER) and mitochondria damage. SnRNA-seq analysis revealed 16 clusters and cell-type-specific gene expression characterization in the pig pancreas. Notably, clusters of Ainar-M and Endocrine-U were observed at the intermediate state between the exocrine and endocrine pancreas. Beta cells of the PIGinH11 group demonstrated the dysfunction with insulin produced and secret decreased and ER stress. Moreover, like clinic patients, acinar cells expressed fewer digestive enzymes and showed organelle damage. We hypothesize that TXNIP that is upregulated by high glucose might play an important role in the dysfunction of endocrine to exocrine cells in PIGinH11 pigs.

Emerging roles of oxyntomodulin-based glucagon-like peptide-1/glucagon co-agonist analogs in diabetes and obesity

Oxyntomodulin (OXM) is an endogenous peptide hormone secreted from the intestines following nutrient ingestion that activates both glucagon-like peptide-1 (GLP-1) and glucagon receptors. OXM is known to exert various effects, including improvement in glucose tolerance, promotion of energy expenditure, acceleration of liver lipolysis, inhibition of food intake, delay of gastric emptying, neuroprotection, and pain relief. The antidiabetic and antiobesity properties have led to the development of biologically active and enzymatically stable OXM-based analogs with proposed therapeutic promise for metabolic diseases. Structural modification of OXM was ongoing to enhance its potency and prolong half-life, and several GLP-1/glucagon dual receptor agonist-based therapies are being explored in clinical trials for the treatment of type 2 diabetes mellitus and its complications. In the present article, we provide a brief overview of the physiology of OXM, focusing on its structural-activity relationship and ongoing clinical development.

Guf1 overexpression improves pancreatic β cell functions in type 2 diabetes mellitus rats with Roux-en-Y gastric bypass (RYGB) surgery

The Roux-en-Y gastric bypass (RYGB) is a one-of-a-kind treatment among contemporary bariatric surgical procedures, and its therapeutic effects for type 2 diabetes mellitus (T2DM) are satisfactory. The present study performed isobaric tags for relative and absolute quantification (iTRAQ) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis identifying different proteomics between T2DM rats with or without Roux-en-Y gastric bypass (RYGB) surgery, and GTP binding elongation factor GUF1 (Guf1) was first found to be significantly upregulated in rats from the T2DM plus RYGB group. In the cellular lipotoxicity model induced by palmitic acid stimulation of rat pancreatic beta cell line, INS-1, palmitic acid treatment inhibited cell viability, suppressed GSIS, promoted lipid droplet formation, promoted cell apoptosis, and induced mitochondrial membrane potential loss. The effects of palmitic acid on INS-1 cells mentioned above could be partially eliminated by Guf1 overexpression but aggravated by Guf1 knockdown. Last, under palmitic acid treatment, Guf1 overexpression promotes the PI3K/Akt and NF-κB signaling but inhibits the AMPK activation. Guf1 is upregulated in T2DM rats who received RYGB, and Guf1 overexpression improves cell mitochondrial functions, increases cell proliferation, inhibits cell apoptosis, and promotes cell functions in palmitic acid-treated β cells.

First-phase insulin secretion: can its evaluation direct therapeutic approaches?

Our work is aimed at unraveling the role of the first-phase insulin secretion in the natural history of type 2 diabetes mellitus (T2DM) and its interrelationship with insulin resistance and with β cell function and mass. Starting from pathophysiology, we investigate the impact of impaired secretion on glucose homeostasis and explore postmeal hyperglycemia as the main clinical feature, underlining its relevance in the management of the disease. We also review dietary and pharmacological approaches aimed at improving early secretory defects and restoring residual β cell function. Furthermore, we discuss possible approaches to detect early secretory defects in clinical practice. By providing a journey through human and animal data, we attempt a unification of the recent evidence in an effort to offer a new outlook on β cell secretion.

Targeted Delivery of Butyrate Improves Glucose Homeostasis, Reduces Hepatic Lipid Accumulation and Inflammation in db/db Mice

Butyrate produced by the gut microbiota has beneficial effects on metabolism and inflammation. Butyrate-producing bacteria are supported by diets with a high fiber content, such as high-amylose maize starch (HAMS). We investigated the effects of HAMS- and butyrylated HAMS (HAMSB)-supplemented diets on glucose metabolism and inflammation in diabetic db/db mice. Mice fed HAMSB had 8-fold higher fecal butyrate concentration compared to control diet-fed mice. Weekly analysis of fasting blood glucose showed a significant reduction in HAMSB-fed mice when the area under the curve for all five weeks was analyzed. Following treatment, fasting glucose and insulin analysis showed increased homeostatic model assessment (HOMA) insulin sensitivity in the HAMSB-fed mice. Glucose-stimulated insulin release from isolated islets did not differ between the groups, while insulin content was increased by 36% in islets of the HAMSB-fed mice. Expression of insulin 2 was also significantly increased in islets of the HAMSB-fed mice, while no difference in expression of insulin 1, pancreatic and duodenal homeobox 1, MAF bZIP transcription factor A and urocortin 3 between the groups was observed. Hepatic triglycerides in the livers of the HAMSB-fed mice were significantly reduced. Finally, mRNA markers of inflammation in liver and adipose tissue were reduced in mice fed HAMSB. These findings suggest that HAMSB-supplemented diet improves glucose metabolism in the db/db mice, and reduces inflammation in insulin-sensitive tissues.

Deficiency of transcription factor Nkx6.1 does not prevent insulin secretion in INS-1E cells

Pancreatic-β-cell-specifying transcription factor Nkx6.1, indispensable for embryonic development of the pancreatic epithelium and commitment to β-cell lineage, directly controls the expression of a glucose transporter (Glut2), pyruvate carboxylase (Pcx), and genes for insulin processing (endoplasmic reticulum oxidoreductase-1β, Ero1lb; zinc transporter-8, Slc30a8). The Nkx6.1 decline in aging diabetic Goto-Kakizaki rats contributes to β-cell trans-differentiation into δ-cells. Elucidating further Nkx6.1 roles, we studied Nkx6.1 ablation in rat INS-1E cells, prepared by CRISPR/Cas9 gene editing from single colonies. INS-1E^Nkx6.1-/- cells exhibited unchanged glucose-stimulated insulin secretion (GSIS), moderately decreased phosphorylating/non-phosphorylating respiration ratios at high glucose; unchanged but delayed ATP-elevation responses to glucose; delayed uptake of fluorescent glucose analog, but slightly improved cytosolic Ca²⁺-oscillations, induced by glucose; despite approximately halved Glut2, Pcx, Ero1lb, and Slc30a8 expression, and reduced nuclear receptors Nr4a1 and Nr4a3. Thus, ATP synthesis was time-compensated, despite the delayed GLUT2-mediated glucose uptake and crippled pyruvate-malate redox shuttle (owing to the PCX-deficiency) in INS-1E^Nkx6.1-/- cells. Nkx6.1 thus controls the expression of genes that are not essential for acute insulin secretion, the function of which can be compensated for. Considerations that Nkx6.1 deficiency is an ultimate determinant of β-cell pathology beyond cell trans-(de-)differentiation or β-cell identity are not supported by our results.

Current Insights on the Use of Insulin and the Potential Use of Insulin Mimetics in Targeting Insulin Signalling in Alzheimer's Disease

Alzheimer's disease (AD) and type 2 diabetes (T2D) are chronic diseases that share several pathological mechanisms, including insulin resistance and impaired insulin signalling. Their shared features have prompted the evaluation of the drugs used to manage diabetes for the treatment of AD. Insulin delivery itself has been utilized, with promising effects, in improving cognition and reducing AD related neuropathology. The most recent clinical trial involving intranasal insulin reported no slowing of cognitive decline; however, several factors may have impacted the trial outcomes. Long-acting and rapid-acting insulin analogues have also been evaluated within the context of AD with a lack of consistent outcomes. This narrative review provided insight into how targeting insulin signalling in the brain has potential as a therapeutic target for AD and provided a detailed update on the efficacy of insulin, its analogues and the outcomes of human clinical trials. We also discussed the current evidence that warrants the further investigation of the use of the mimetics of insulin for AD. These small molecules may provide a modifiable alternative to insulin, aiding in developing drugs that selectively target insulin signalling in the brain with the aim to attenuate cognitive dysfunction and AD pathologies.

Design of Improved Antidiabetic Drugs: A Journey from Single to Multitarget Agents

Multifactorial diseases exhibit a complex pathophysiology with several factors contributing to their pathogenesis and development. Examples of such disorders are neurodegenerative (e. g. Alzheimer's, Parkinson's) and cardiovascular diseases (e. g. atherosclerosis, metabolic syndrome, diabetes II). Traditional therapeutic approaches with single-target drugs have been proven, in many cases, unsatisfactory for the treatment of multifactorial diseases such as diabetes II. The well-established by now strategy of multitarget drugs is constantly gaining interest and momentum, as a more effective approach. The development of pharmacomolecules able to simultaneously modulate multiple relevant-to-the-disease targets has already several successful examples in various fields and has, as such, inspired the design of multitarget antidiabetic agents; this review highlights the design aspect and efficacy of this approach for improved antidiabetics by presenting several examples of successful pharmacophore combinations in (multitarget) agents that modulate two or more molecular targets involved in diabetes II, resulting in a superior antihyperglycemic profile.

Severe Obstructive Sleep Apnea Disrupts Vigilance-State-Dependent Metabolism

The direct pathophysiological effects of obstructive sleep apnea (OSA) have been well described. However, the systemic and metabolic consequences of OSA are less well understood. The aim of this secondary analysis was to translate recent findings in healthy subjects on vigilance-state-dependent metabolism into the context of OSA patients and answer the question of how symptomatic OSA influences metabolism and whether these changes might explain metabolic and cardiovascular consequences of OSA. Patients with suspected OSA were assigned according to their oxygen desaturation index (ODI) and Epworth Sleepiness Scale (ESS) score into symptomatic OSA and controls. Vigilance-state-dependent breath metabolites assessed by high-resolution mass spectrometry were used to test for a difference in both groups. In total, 44 patients were eligible, of whom 18 (40.9%) were assigned to the symptomatic OSA group. Symptomatic OSA patients with a median [25%, 75% quartiles] ODI of 40.5 [35.0, 58.8] events/h and an ESS of 14.0 [11.2, 15.8] showed moderate to strong evidence for differences in 18 vigilance-state-dependent breath compounds compared to controls. These identified metabolites are part of major metabolic pathways in carbohydrate, amino acid, and lipid metabolism. Thus, beyond hypoxia per se, we hypothesize that disturbed sleep in OSA patients persists as disturbed sleep-dependent metabolite levels during daytime.

Cross talk between exosomes and pancreatic β-cells in diabetes

Exosomes are a class of extracellular vesicles with a diameter of 50-100 nm secreted by various cells. They are generated through complex intracellular production mechanisms before being secreted to the extracellular environment. Due to their inclusion of proteins, lipids, and nucleic acids, exosomes play an important role in intercellular communication. Pancreatic β-cells play an irreplaceable role in the body's glucose metabolism. Their dysfunction is one of the causes of diabetes. Exosomes of various cells regulate the function of β-cells by regulating autoimmunity, delivering non-coding RNAs, or directly regulating intracellular signal pathways. This communication between β-cells and other cells plays an important role in the pathogenesis and development of diabetes, and has potential for clinical application. This paper reviews the biological sources and functions of exosomes, as well as intercellular crosstalk between β-cells and other cells that is involved in β-cell failure and regeneration.

Butyrate inhibits IL-1β-induced inflammatory gene expression by suppression of NF-κB activity in pancreatic beta cells

Cytokine-induced beta cell dysfunction is a hallmark of type 2 diabetes (T2D). Chronic exposure of beta cells to inflammatory cytokines affects gene expression and impairs insulin secretion. Thus, identification of anti-inflammatory factors that preserve beta cell function represents an opportunity to prevent or treat T2D. Butyrate is a gut microbial metabolite with anti-inflammatory properties for which we recently showed a role in preventing interleukin-1β (IL-1β)-induced beta cell dysfunction, but how prevention is accomplished is unclear. Here, we investigated the mechanisms by which butyrate exerts anti-inflammatory activity in beta cells. We exposed mouse islets and INS-1E cells to a low dose of IL-1β and/or butyrate and measured expression of inflammatory genes and nitric oxide (NO) production. Additionally, we explored the molecular mechanisms underlying butyrate activity by dissecting the activation of the nuclear factor-κB (NF-κB) pathway. We found that butyrate suppressed IL-1β-induced expression of inflammatory genes, such as Nos2, Cxcl1, and Ptgs2, and reduced NO production. Butyrate did not inhibit IκBα degradation nor NF-κB p65 nuclear translocation. Furthermore, butyrate did not affect binding of NF-κB p65 to target sequences in synthetic DNA but inhibited NF-κB p65 binding and RNA polymerase II recruitment to inflammatory gene promoters in the context of native DNA. We found this was concurrent with increased acetylation of NF-κB p65 and histone H4, suggesting butyrate affects NF-κB activity via inhibition of histone deacetylases. Together, our results show butyrate inhibits IL-1β-induced inflammatory gene expression and NO production through suppression of NF-κB activation and thereby possibly preserves beta cell function.

Discovery of once-weekly, peptide-based selective GLP-1 and cholecystokinin 2 receptors co-agonizts

A group of long-acting, peptide-based, and selective GLP-1R/CCK-2R dual agonizts were identified by rational design. Guided by sequence analysis, structural elements of the CCK-2R agonist moiety were engineered into the GLP-1R agonist Xenopus GLP-1, resulting in hybrid peptides with potent GLP-1R/CCK-2R dual activity. Further modifications with fatty acids resulted in novel metabolically stable peptides, among which 3d and 3 h showed potent GLP-1R and CCK-2R activation potencies and comparable stability to semaglutide. In food intake tests, 3d and 3 h also showed a potent reduction in food intake, superior to that of semaglutide. Moreover, the acute hypoglycemic and insulinotropic activities of 3d and 3 h were better than that of semaglutide and ZP3022. Importantly, the limited pica response following 3d and 3 h administration in SD rats preliminarily indicated that the food intake reduction effects of 3d and 3 h are independent of nausea/vomiting. In a 35-day study in db/db mice, every two days administration of 3d and 3 h increased islet areas and numbers, insulin contents, β-cell area, β-cell proliferation, as well as improved glucose tolerance, and decreased HbA1c, to a greater extent than ZP3022 and semaglutide. In a 21-day study in DIO mice, once-weekly administration of 3d and 3 h significantly induced body weight loss, improved glucose tolerance, and normalized lipid metabolism, to a greater extent than semaglutide. The current study showed the antidiabetic and antiobesity potentials of GLP-1R/CCK-2R dual agonizts that warrant further investigation.

Candidate master microRNA regulator of arsenic-induced pancreatic beta cell impairment revealed by multi-omics analysis

Arsenic is a pervasive environmental toxin that is listed as the top priority for investigation by the Agency for Toxic Substance and Disease Registry. While chronic exposure to arsenic is associated with type 2 diabetes (T2D), the underlying mechanisms are largely unknown. We have recently demonstrated that arsenic treatment of INS-1 832/13 pancreatic beta cells impairs glucose-stimulated insulin secretion (GSIS), a T2D hallmark. We have also shown that arsenic alters the microRNA profile of beta cells. MicroRNAs have a well-established post-transcriptional regulatory role in both normal beta cell function and T2D pathogenesis. We hypothesized that there are microRNA master regulators that shape beta cell gene expression in pathways pertinent to GSIS after exposure to arsenicals. To test this hypothesis, we first treated INS-1 832/13 beta cells with either inorganic arsenic (iAsIII) or monomethylarsenite (MAsIII) and confirmed GSIS impairment. We then performed multi-omic analysis using chromatin run-on sequencing, RNA-sequencing, and small RNA-sequencing to define profiles of transcription, gene expression, and microRNAs, respectively. Integrating across these data sets, we first showed that genes downregulated by iAsIII treatment are enriched in insulin secretion and T2D pathways, whereas genes downregulated by MAsIII treatment are enriched in cell cycle and critical beta cell maintenance factors. We also defined the genes that are subject primarily to post-transcriptional control in response to arsenicals and demonstrated that miR-29a is the top candidate master regulator of these genes. Our results highlight the importance of microRNAs in arsenical-induced beta cell dysfunction and reveal both shared and unique mechanisms between iAsIII and MAsIII.

Nanocarriers System for Vitamin D as Nutraceutical in Type 2 Diabetes: A Review

Incidence of diabetes are common among population around the world. Diabetes may lead to other complication and increasing morbidity and mortality. Many ways have been done to treat and prevent the development of diabetes. In addition of conventional pharmacotherapy, therapeutic therapy shown good opportunity to maintain and improve diabetic conditions. Vitamin D3 is known as nutraceutical and has good opportunity to develop the medication of type 2 diabetes. In another way, vitamin D3 naturally easy to damage by environmental condition. To overcome this weakness, researcher around the world have developed the method for protecting unstable compound as vitamin D3 with encapsulation. Liprotide is one of the various materials which can be used for encapsulation. Combination of lipid and protein molecules is expected to be a carrier and protector of vitamin D3 in gastrointestinal system. Here we review the research advances of liprotide as nanocarriers and vitamin D3 as nutraceuticals to discuss in applied on type 2 diabetes.

Adipose Tissue Secretion Pattern Influences β-Cell Wellness in the Transition from Obesity to Type 2 Diabetes

The dysregulation of the β-cell functional mass, which is a reduction in the number of β-cells and their ability to secure adequate insulin secretion, represents a key mechanistic factor leading to the onset of type 2 diabetes (T2D). Obesity is recognised as a leading cause of β-cell loss and dysfunction and a risk factor for T2D. The natural history of β-cell failure in obesity-induced T2D can be divided into three steps: (1) β-cell compensatory hyperplasia and insulin hypersecretion, (2) insulin secretory dysfunction, and (3) loss of β-cell mass. Adipose tissue (AT) secretes many hormones/cytokines (adipokines) and fatty acids that can directly influence β-cell function and viability. As this secretory pattern is altered in obese and diabetic patients, it is expected that the cross-talk between AT and pancreatic β-cells could drive the maintenance of the β-cell integrity under physiological conditions and contribute to the reduction in the β-cell functional mass in a dysmetabolic state. In the current review, we summarise the evidence of the ability of the AT secretome to influence each step of β-cell failure, and attempt to draw a timeline of the alterations in the adipokine secretion pattern in the transition from obesity to T2D that reflects the progressive deterioration of the β-cell functional mass.

How exposure to chronic stress contributes to the development of type 2 diabetes: A complexity science approach

Chronic stress contributes to the onset of type 2 diabetes (T2D), yet the underlying etiological mechanisms are not fully understood. Responses to stress are influenced by earlier experiences, sex, emotions and cognition, and involve a complex network of neurotransmitters and hormones, that affect multiple biological systems. In addition, the systems activated by stress can be altered by behavioral, metabolic and environmental factors. The impact of stress on metabolic health can thus be considered an emergent process, involving different types of interactions between multiple variables, that are driven by non-linear dynamics at different spatiotemporal scales. To obtain a more comprehensive picture of the links between chronic stress and T2D, we followed a complexity science approach to build a causal loop diagram (CLD) connecting the various mediators and processes involved in stress responses relevant for T2D pathogenesis. This CLD could help develop novel computational models and formulate new hypotheses regarding disease etiology.

Diabetes and Ischemic Stroke: An Old and New Relationship an Overview of the Close Interaction between These Diseases

Diabetes mellitus is a comprehensive expression to identify a condition of chronic hyperglycemia whose causes derive from different metabolic disorders characterized by altered insulin secretion or faulty insulin effect on its targets or often both mechanisms. Diabetes and atherosclerosis are, from the point of view of cardio- and cerebrovascular risk, two complementary diseases. Beyond shared aspects such as inflammation and oxidative stress, there are multiple molecular mechanisms by which they feed off each other: chronic hyperglycemia and advanced glycosylation end-products (AGE) promote ‘accelerated atherosclerosis’ through the induction of endothelial damage and cellular dysfunction. These diseases impact the vascular system and, therefore, the risk of developing cardio- and cerebrovascular events is now evident, but the observation of this significant correlation has its roots in past decades. Cerebrovascular complications make diabetic patients 2–6 times more susceptible to a stroke event and this risk is magnified in younger individuals and in patients with hypertension and complications in other vascular beds. In addition, when patients with diabetes and hyperglycemia experience an acute ischemic stroke, they are more likely to die or be severely disabled and less likely to benefit from the one FDA-approved therapy, intravenous tissue plasminogen activator. Experimental stroke models have revealed that chronic hyperglycemia leads to deficits in cerebrovascular structure and function that may explain some of the clinical observations. Increased edema, neovascularization, and protease expression as well as altered vascular reactivity and tone may be involved and point to potential therapeutic targets. Further study is needed to fully understand this complex disease state and the breadth of its manifestation in the cerebrovasculature.

The root extract of Scutellaria baicalensis Georgi promotes β cell function and protects from apoptosis by inducing autophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellaria baicalensis Georgi (SBG) is a traditional Chinese medicine with a remarkable remedial effect on diabetes mellitus. However, the precise mechanism involved has not been fully elucidated yet. Here, we aimed to explore the anti-diabetes effects of its traditional decoction in vitro and elucidate the autophagy-related mechanism.

AIM OF THE STUDY

This study was designed to investigate the effects of the water extract of SBG (WSB) on the β cell viability, insulin secretion and the mechanism related to autophagy.

MATERIALS AND METHODS

Detection of insulin secretion using an enzyme immunoassay method, and analysis of apoptosis rate in MIN-6 cells by the flow cytometry with PI and Annexin V-FITC staining. In addition, the autophagy levels and pathways were evaluated from the number of autophagosomes and the expression of autophagy-related proteins. 3-Methyladenine (3-MA) was used as the autophagy inhibitor. Autophagosomes were observed using a confocal microscopy, and autophagy-related proteins (LC3-II/I, p62, S6k, p-AMPK/AMPK, p-mTOR/mTOR) were measured by Western blot.

RESULTS

Here we detected a significant increase in insulin release from MIN-6 cells after treated with WSB. It is about 1.6 times as much as that of the control group with 2.8 mM glucose and 2.2 times more than the 16.8 mM glucose group. At the same time, WSB increased the number of autophagosomes and the ratio of LC3 Ⅱ/LC3 Ⅰ, indicating that autophagy were activated in MIN-6 cells. When inhibiting autophagy, there was no significant difference in insulin release between the two groups. The apoptotic rate of the high glucose group was as high as 33.23%. After pretreatment with WSB, the apoptotic rate decreased to 14.95%, and increased to 22.57% when treated with 3-MA and WSB. At the same time, WSB treatment enhanced the phosphorylation of AMPK, but had no significant effect on the expression of mTOR and S6K.

CONCLUSION

Our data suggested that WSB increased insulin secretion and reduced apoptosis under high glucose by inducing autophagy through the AMPK pathway, which elucidated the mechanism of WSB in the treatment of diabetes.

MiR-195 promotes pancreatic β-cell dedifferentiation by targeting Mfn2 and impairing Pi3k/Akt signaling in type 2 diabetes

OBJECTIVE

The aim of this study was to research the role and underlying mechanism of miR-195 involved in pancreatic β-cell dedifferentiation induced by hyperlipemia in type 2 diabetes mellitus.

METHODS

High-fat-diet-induced obese C57BL/6J mice and palmitate-stimulated Min6 cells were used as the models of β-cell dedifferentiation in vivo and in vitro, respectively. The expression of miR-195 and insulin secretion during β-cell dedifferentiation were measured. Also, the influence of regulated miR-195 expression on β-cell dedifferentiation was examined. Meanwhile, the IRS-1/2/Pi3k/Akt pathway and mitofusin-2 (Mfn2) expression were investigated during β-cell dedifferentiation.

RESULTS

MiR-195 was upregulated during lipotoxicity-induced β-cell dedifferentiation in both in vivo and in vitro experiments, and miR-195 functionally contributed to lipotoxicity-induced β-cell dedifferentiation. Furthermore, miR-195 inhibited IRS-1/2/Pi3k/Akt pathway activation, which accompanied β-cell dedifferentiation. Mfn2, a target of miR-195, was found to be downregulated and was associated with increased mitochondrial production of reactive oxygen species during β-cell dedifferentiation. Instructively, inhibition of miR-195, at least partially, reversed the downregulation of Mfn2, restored IRS-1/2/Pi3k/Akt pathway activation, and prevented β-cell dedifferentiation.

CONCLUSIONS

MiR-195 promoted β-cell dedifferentiation through negatively regulating Mfn2 expression and inhibiting the IRS-1/2/Pi3k/Akt pathway, providing a promising treatment for type 2 diabetes mellitus.

Emergence of microneedles as a potential therapeutics in diabetes mellitus

Diabetes mellitus is a severe condition in which the pancreas produces inadequate insulin or the insulin generated is ineffective for utilisation by the body; as a result, insulin therapy is required for control blood sugar levels in patients having type 1 diabetes and is widely recommended in advanced type 2 diabetes patients with uncontrolled diabetes despite dual oral therapy, while subcutaneous insulin administration using hypodermic injection or pump-mediated infusion is the traditional route of insulin delivery and causes discomfort, needle phobia, reduced adherence, and risk of infection. Therefore, transdermal insulin delivery has been extensively explored as an appealing alternative to subcutaneous approaches for diabetes management which not only is non-invasive and easy, but also avoids first-pass metabolism and prevents gastrointestinal degradation. Microneedles have been commonly investigated in human subjects for transdermal insulin administration because they are minimally invasive and painless. The different types of microneedles developed for the transdermal delivery of anti-diabetic drugs are discussed in this review, including solid, dissolving, hydrogel, coated, and hollow microneedles. Numerous microneedle products have entered the market in recent years. But, before the microneedles can be effectively launched into the market, a significant amount of investigation is required to address the numerous challenges. In conclusion, the use of microneedles in the transdermal system is an area worth investigating because of its significant benefits over the oral route in the delivery of anti-diabetic medications and biosensing of blood sugar levels to assure improved clinical outcomes in diabetes management.

Non-coding RNAs in diabetes mellitus and diabetic cardiovascular disease

More than 10% of the world's population already suffers from varying degrees of diabetes mellitus (DM), but there is still no cure for the disease. Cardiovascular disease (CVD) is one of the most common and dangerous of the many health complications that can be brought on by DM, and has become the leading cause of death in people with diabetes. While research on DM and associated CVD is advancing, the specific mechanisms of their development are still unclear. Given the threat of DM and CVD to humans, the search for new predictive markers and therapeutic ideas is imminent. Non-coding RNAs (ncRNAs) have been a popular subject of research in recent years. Although they do not encode proteins, they play an important role in living organisms, and they can cause disease when their expression is abnormal. Numerous studies have observed aberrant ncRNAs in patients with DM complications, suggesting that they may play an important role in the development of DM and CVD and could potentially act as biomarkers for diagnosis. There is additional evidence that treatment with existing drugs for DM, such as metformin, alters ncRNA expression levels, suggesting that regulation of ncRNA expression may be a key mechanism in future DM treatment. In this review, we assess the role of ncRNAs in the development of DM and CVD, as well as the evidence for ncRNAs as potential therapeutic targets, and make use of bioinformatics to analyze differential ncRNAs with potential functions in DM.

Pancreatic islet cells disarray, apoptosis, and proliferation in obese mice. The role of Semaglutide treatment

There are significant injuries of pancreatic islets due to obesity and insulin resistance. Therefore, GLP-1 receptor agonists like Semaglutide might benefit the islet structural remodeling and its endocrine function in diet-induced obese mice. One-month-old male C57BL/6 mice were allotted into two dietary groups (n = 60/group) and fed for 16 weeks a control diet (C) or a high‒fat diet (HF). Then, for an additional four weeks, the main groups were resampled to include treatment (Semaglutide, S, 40 μg/kg), or paired feed with the treated group (PF), totaling six groups (n = 20/group): C, CS, CPF, HF, HFS, HFPF. Biochemistry, stereology, immunohistochemistry/immunofluorescence, confocal microscopy, and RT-qPCR were used in the study. The mouse model reproduced metabolism and bodily changes due to diet-induced obesity. Pancreatic islet hypertrophy was observed with alpha- and beta-cell remodeling, cell disarray, and apoptosis. Semaglutide increased islet cell proliferation and recovered islet size and alpha- and beta-cell masses. The changes include recovery of glucose and hormone levels, reduction of pro-inflammatory markers, improvement of pancreatic duodenal homeobox 1 (PDX-1), glucose transporter 2 (GLUT-2), v-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MAF-A), and peroxisome proliferator-activated receptors (PPAR) -gamma. In conclusion, damage to the pancreatic islet caused by insulin resistance and the attempt to adapt the islet of obese mice involved different pathways, especially the pro-inflammatory pathway, PDX1, and PPAR-alpha and gamma. Semaglutide showed beneficial effects on these pathways, reducing the lesion on the islet. However, the weight loss influence of Semaglutide was of little relevance in the pancreatic islet.

Behavioral Sciences in the Optimization of Pharmacological and Non-Pharmacological Therapy for Type 2 Diabetes

Type 2 diabetes mellitus is one of the main chronic diseases worldwide, with a significant impact on public health. Behavioral changes are an important step in disease prevention and management, so the way in which individuals adapt their lifestyle to new circumstances will undoubtedly be a predictor of the success of the treatments instituted, contributing to a reduction in the morbidity and mortality that may be associated with them. It is essential to prepare and educate all diabetic patients on the importance of changing behavioral patterns in relation to the disease, with health professionals assuming an extremely important role in this area, both from a pharmacological and non-pharmacological point of view, and also ensuring the monitoring of the progress of these measures. Diabetes is a chronic disease that requires a high self-management capacity on the part of patients in order to achieve success in treating the disease, and non-adherence to therapy or non-compliance with the previously defined plan, together with an erratic lifestyle, will contribute to failure in controlling the disease. The lower adherence to pharmacological and non-pharmacological treatment in diabetes is mainly correlated to socio-economic aspects, lower health literacy, the side effects associated with the use of antidiabetic therapy or even the concomitant use of several drugs. This article consists of a narrative review that aims to synthesize the findings published in the literature, retrieved by searching databases, manuals, previously published scientific articles and official texts, following the methodology of the Scale for Assessment of Narrative Review Articles (SANRA). We aim to address the importance of behavioral sciences in the treatment of diabetes, in order to assess behavior factors and barriers for behavior changes that have an impact on the therapeutic and non-therapeutic optimization in patients with type 2 diabetes mellitus control.

Peripherally active dextromethorphan derivatives lower blood glucose levels by targeting pancreatic islets

Dextromethorphan (DXM) acts as cough suppressant via its central action. Cell-protective effects of this drug have been reported in peripheral tissues, making DXM potentially useful for treatment of several common human diseases, such as type 2 diabetes mellitus (T2DM). Pancreatic islets are among the peripheral tissues that positively respond to DXM, and anti-diabetic effects of DXM were observed in two placebo-controlled, randomized clinical trials in humans with T2DM. Since these effects were associated with central side effects, we here developed chemical derivatives of DXM that pass the blood-brain barrier to a significantly lower extent than the original drug. We show that basic nitrogen-containing residues block central adverse events of DXM without reducing its anti-diabetic effects, including the protection of human pancreatic islets from cell death. These results show how to chemically modify DXM, and possibly other morphinans, as to exclude central side effects, while targeting peripheral tissues, such as pancreatic islets.

Emerging roles of PHLPP phosphatases in metabolism

Over the last decades, research has focused on the role of pleckstrin homology (PH) domain leucine-rich repeat protein phosphatases (PHLPPs) in regulating cellular signaling via PI3K/Akt inhibition. The PKB/Akt signaling imbalances are associated with a variety of illnesses, including various types of cancer, inflammatory response, insulin resistance, and diabetes, demonstrating the relevance of PHLPPs in the prevention of diseases. Furthermore, identification of novel substrates of PHLPPs unveils their role as a critical mediator in various cellular processes. Recently, researchers have explored the increasing complexity of signaling networks involving PHLPPs whereby relevant information of PHLPPs in metabolic diseases was obtained. In this review, we discuss the current knowledge of PHLPPs on the well-known substrates and metabolic regulation, especially in liver, pancreatic beta cell, adipose tissue, and skeletal muscle in relation with the stated diseases. Understanding the context-dependent functions of PHLPPs can lead to a promising treatment strategy for several kinds of metabolic diseases.

The increasing trend of Type 2 diabetes in youth: An overview

INTRODUCTION

Pediatric Type 2 Diabetes Mellitus (T2DM) is increasing in incidence, largely in correlation with global childhood obesity crisis.

COMPLICATIONS

Early detection and treatment are vital as diabetes has been shown to progress rapidly and aggressively amongst children.

ETIOLOGY

Higher than expected insulin levels compared to adults, leads to more rapid β cell decline.

TREATMENTS

New treatments to control glycemic levels among youth with T2DM are being evaluated. This review summarizes the current understanding of causes, complications, and treatments for youth diagnosed with T2DM. OR. Pediatric Type 2 Diabetes Mellitus (T2DM) is increasing in incidence, largely in correlation with the global childhood obesity crisis. With increase in cases comes new challenges for medical professionals. Early detection and treatment are vital as the disease has been shown to progress aggressively and bring complications to children at a rapid rate. New treatments are currently being studied to control glycemic levels among youth with T2DM, as current options are not as effective chronically in children as in adults. This review summarizes the current understanding of causes, complications, and treatments for youth diagnosed with T2DM.

Serum fatty acid-binding protein 4 levels and responses of pancreatic islet β-cells and α-cells in patients with type 2 diabetes

BACKGROUND

Serum fatty acid-binding protein 4 (FABP4), as an intracellular lipid chaperone and adipokine, was reported to be related to the incidence of type 2 diabetes (T2D) and diabetic complications, but its association with pancreatic islet β-cell and α-cell functions has not been fully elucidated. So the present study was to investigate the serum FABP4 levels and responses of islet β-cells and α-cells in patients with T2D.

METHODS

115 patients with T2D and 89 healthy controls (HC), who received serum FABP4 levels test, were recruited to participate in this study. Moreover, 75-g oral glucose tolerance test (OGTT) was performed in T2D patients to evaluate islet β-cell and α-cell functions. Systemic insulin sensitivity and overall insulin secretion of islet β-cell function were assessed by Matsuda index using C peptide (ISI_M-cp) and ratio of the area under the C peptide curve to the glucose curve (AUC_cp/glu) during OGTT, respectively. Fasting glucagon (Gluca_0min) and postchallenge glucagon assessed by the area under the glucagon curve (AUC_gluca) were determined during OGTT to evaluate islet α-cell function. And other various clinical variables were also measured in all participants. Skewed variables were natural log-transformed (ln), such as lnFABP4.

RESULTS

The serum FABP4 levels in T2D patients were significantly higher than those in HC (p < 0.05). And after partially adjusting for fasting plasma glucose, serum lnFABP4 levels were negatively correlated with lnISI_M-cp (r =  - 0.332, p < 0.001) and positively correlated with lnAUC_cp/glu (r = 0.324, p < 0.001), lnGluca_0min (r = 0.200, p = 0.040) and lnAUC_gluca (r = 0.311, p < 0.001), respectively, in patients with T2D. Furthermore, when multiple linear regression analyses were applied to adjust for other various clinical variables, serum lnFABP4 levels were found to remain associated with lnISI_M-cp (β =  - 0.296, t =  - 2.900, p = 0.005), lnAUC_cp/glu (β = 0.223, t = 2.038, p = 0.046), lnGluca_0min (β = 0.272, t = 2.330, p = 0.024) and lnAUC_gluca (β = 0.341, t = 3.065, p = 0.004), respectively.

CONCLUSION

Increased serum FABP4 levels were closely associated with blunted insulin sensitivity, increased insulin secretion, and elevated fasting and postchallenge glucagon levels in patients with T2D.

Towards Goals to Refine Prophylactic and Therapeutic Strategies Against COVID-19 Linked to Aging and Metabolic Syndrome

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) gave rise to the coronavirus disease 2019 (COVID-19) pandemic. A strong correlation has been demonstrated between worse COVID-19 outcomes, aging, and metabolic syndrome (MetS), which is primarily derived from obesity-induced systemic chronic low-grade inflammation with numerous complications, including type 2 diabetes mellitus (T2DM). The majority of COVID-19 deaths occurs in people over the age of 65. Individuals with MetS are inclined to manifest adverse disease consequences and mortality from COVID-19. In this review, we examine the prevalence and molecular mechanisms underlying enhanced risk of COVID-19 in elderly people and individuals with MetS. Subsequently, we discuss current progresses in treating COVID-19, including the development of new COVID-19 vaccines and antivirals, towards goals to elaborate prophylactic and therapeutic treatment options in this vulnerable population.

Harnessing the Endogenous Plasticity of Pancreatic Islets: A Feasible Regenerative Medicine Therapy for Diabetes?

Diabetes is a chronic metabolic disease caused by an absolute or relative deficiency in functional pancreatic β-cells that leads to defective control of blood glucose. Current treatments for diabetes, despite their great beneficial effects on clinical symptoms, are not curative treatments, leading to a chronic dependence on insulin throughout life that does not prevent the secondary complications associated with diabetes. The overwhelming increase in DM incidence has led to a search for novel antidiabetic therapies aiming at the regeneration of the lost functional β-cells to allow the re-establishment of the endogenous glucose homeostasis. Here we review several aspects that must be considered for the development of novel and successful regenerative therapies for diabetes: first, the need to maintain the heterogeneity of islet β-cells with several subpopulations of β-cells characterized by different transcriptomic profiles correlating with differences in functionality and in resistance/behavior under stress conditions; second, the existence of an intrinsic islet plasticity that allows stimulus-mediated transcriptome alterations that trigger the transdifferentiation of islet non-β-cells into β-cells; and finally, the possibility of using agents that promote a fully functional/mature β-cell phenotype to reduce and reverse the process of dedifferentiation of β-cells during diabetes.