Apoptosis of beta cells in diabetes mellitus

Hyperglycemia influences the cell proliferation and death of the rat endocrine pancreas in the neonatal period

AIMS

To evaluate the cell proliferation and death, and structural morphology of the pancreatic islet cells of the rats with hyperglycemia in the first month of life and compare to those of the control rats.

MAIN METHODS

Female Sprague-Dawley newborn rats received Streptozotocin (a beta-cytotoxic drug) at birth for diabetes induction. Control and hyperglycemic animals were euthanized on different days of life: 5, 10, 15, and 30. The pancreas was collected and processed for immunohistochemical analysis of cleaved Caspase-3 (cell death), Ki-67 (cell proliferation), PDX-1 (transcription factor responsible for insulin synthesis), and endocrine hormones (insulin, glucagon, and somatostatin).

KEY FINDINGS

Control females showed a higher percentage (%) of Ki-67-positive(+) cells on D10 and D15, a higher % of insulin+ and somatostatin+ cells on D15 and D30, a lower % of PDX-1+ cells on D10, and a higher % of glucagon+ cells on D10 and D30. Hyperglycemic females showed a lower % of Ki-67+ cells on D15, a higher % of cleaved Caspase-3+ cells on D15, and insulin+ cells on D15 and D30. In the comparison among the experimental groups, the hyperglycemic females showed an increased % of cleaved Caspase-3+ and Ki-67+ cells and a lower % of PDX-1+ cells.

SIGNIFICANCE

This study enabled a better understanding of the abnormal pancreas development regarding cellular proliferation, apoptosis, and hormonal synthesis in the neonatal period. Thus, the pancreatic islets of hyperglycemic rats do not reestablish the normal endocrine cell population, and cellular apoptosis overcame the proliferative activity of these cells.

Hyaluronic acid-g-lipoic acid granular gel for promoting diabetic wound healing

Diabetic patients are prone to developing chronic inflammation after trauma and have persistent nonhealing wounds. Reactive oxygen species (ROS) and recurrent bacterial infections at the site of long-term wounds also further delay skin wound healing and tissue regeneration. In this study, a granular gel (which exhibits ROS scavenging and antibacterial properties) is fabricated based on hyaluronic acid-g-lipoic acid (HA-LA). Briefly, HA-LA is synthesized to fabricate HA-LA microgels, which are further assembled by Ag+ via its coordination effect with disulfide in dithiolane to form a granular gel. The extrudable bulk granular gel possesses a shear-thinning feature and is immediately restored to a solid state after extrusion, and this can be easily applied to the whole wound area. Therefore, the grafted LA not only allows for the construction of the granular gel but also removes excess ROS from the microenvironment. Additionally, the presence of Ag+ realizes the assembly of microgels and has antibacterial effects. In vivo experiments show that the HA-LA granular gel eliminates excessive ROS at the wound site and up-regulates the secretion of reparative growth factors, thus, accelerating common and diabetic wound healing significantly. Therefore, the ROS-scavenging granular gel that can be applied to the wound surface with chronic inflammation demonstrates strong clinical utility.

Protective effect of ischaemic postconditioning combined with nicorandil on myocardial ischaemia‒reperfusion injury in diabetic rats

BACKGROUND

The diabetic heart exhibits a high sensitivity to ischaemia/reperfusion (I/R) injury. Diabetes mellitus (DM) can affect the efficacy of cardioprotective interventions and reduce the therapeutic potential of existing treatment options. This study aimed to investigate the feasibility of shifting from monotherapy to combination therapy in diabetic myocardial I/R injury.

METHODS

6-8 week rats were randomized into 10 groups: sham, I/R, ischaemia postconditioning (I-Post), nicorandil (Nic), combination therapy (I-Post + Nic), DM sham, DM I/R, DM I-Post, DM Nic and DM I-Post + Nic. The extent of myocardial injury was clarified by measuring CK-MB and NO levels in plasma, ROS content in myocardial tissues, and TTC/Evans Blue staining to assess the area of myocardial infarction. Pathological staining of cardiac tissue sections were performed to clarify the structural changes in myocardial histopathology. Finally, Western blotting was performed to detect the phosphorylation levels of some key proteins in the PI3K/Akt signalling pathway in myocardial tissues.

RESULTS

We confirms that myocardial injury in diabetic I/R rats remained at a high level after treatment with I-Post or nicorandil alone. I-Post combined with nicorandil showed better therapeutic effects in diabetic I/R rats, and the combined treatment further reduced the area of myocardial injury in diabetic I/R rats compared with I-Post or nicorandil treatment alone (P < 0.001), as well as the levels of the myocardial injury markers CK-MB and ROS (P < 0.001); it also significantly increased plasma NO levels. Pathological staining also showed that diabetic rats benefited significantly from the combination therapy. Further mechanistic studies confirmed this finding. The protein phosphorylation levels of PI3K/Akt signalling pathway in the heart tissue of diabetic I/R rats were significantly higher after the combination treatment than after one treatment alone (all P < 0.05).

CONCLUSION

I-Post combined with nicorandil treatment maintains effective cardioprotection against diabetic myocardial I/R injury by activating the PI3K/Akt signalling pathway.

Aqueous extract of Stevia rebaudiana (Bertoni) Bertoni abrogates death-related signaling pathways via boosting the expression profile of oxidative defense systems

Indigenous inhabitants of South America and other areas have been using stevia as a traditional medicine for years, but its impact on cell signaling pathways has not been well studied yet. We evaluated the impacts of aqueous extract of Stevia rebaudiana (Bertoni) Bertoni on the expression of the selected genes involved in significant cell death modalities, including p53-DNA damage and the cellular antioxidative defense in pancreatic tissues in STZ-induced diabetic rats and murine pancreatic cell lines. The in vivo study revealed that aqueous extract of Stevia significantly upregulated the expression of GSTM1 and P1 and GPX (4.67, 12.08, and 2.81 fold, respectively; all p < .05) along with significant downregulation of the genes which were upregulated by STZ, including apoptotic genes caspase-3 and -9 (-9.80 and -4.16 fold, p < .05, respectively) and necroptotic genes, RIP1K, 2 K, and 3 K (-9.48, -2.70, and -12.9 fold, respectively, all p < .05). In vitro studies also revealed comparable results. In conclusion, the observed clinical improvements in diabetic rats are the result of overexpression of major genes of antioxidative defense systems in the course of a significant downregulation of major cell death modalities. PRACTICAL APPLICATIONS: The popularity of noncaloric sweeteners, including stevia, has rocketed in recent years, but the consumption of stevia as traditional medicine has a long history. The findings of the current study provide strong mechanistic lines of evidence supporting the beneficial biological effects of stevia as a noncaloric sweetener in diabetes.

A systematic review on the metabolic effects of chlorpyrifos

Organophosphate (OP) pesticides, including chlorpyrifos (CPF), can alter metabolic hemostasis. The current systematic study investigated blood glucose, lipid profiles, and body weight alterations in rodents and fish exposed to CPF. The systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Guidelines, querying online databases, including Web of Science, PubMed, and Scopus and also search engine including Google Scholar, through January 2021. Studies on rodent and fish exposed to CPF assessing metabolic functions were selected. All studies were in the English language, with other languages being excluded from the review. Two investigators independently assessed each of the articles. The first author's name, publication date, animal model, age, sample size, gender, dose, duration, and route of exposure and outcomes were extracted from each publication. The present review summarizes findings from 61 publications on glycemic, lipid profile, insulin, and body weight changes in rodents and fish exposed to CPF exposure. Most of the studies reported hyperglycemia, hyperlipidemia, and decreased insulin levels and body weight following exposure to CPF. Additionally, we confirmed that the CPF-induced metabolic alterations were both dose- and time-dependent. Our findings support an association between CPF exposure and metabolic diseases. However, more studies are needed to identify the metabolic-disrupting effects of CPF and their underlying mechanisms.

In silico identification of single nucleotide variations at CpG sites regulating CpG island existence and size

Genetic and epigenetic modifications of genes involved in the key regulatory pathways play a significant role in the pathophysiology and progression of multifactorial diseases. The present study is an attempt to identify single nucleotide variations (SNVs) at CpG sites of promoters of ACAT1, APOB, APOE, CYBA, FAS, FLT1, KSR2, LDLR, MMP9, PCSK9, PHOX2A, REST, SH2B3, SORT1 and TIMP1 genes influencing CpG island (CGI) existence and size associated with the pathophysiology of Diabetes mellitus, Coronary artery disease and Cancers. Promoter sequences located between -2000 to + 2000 bp were retrieved from the EPDnew database and predicted the CpG island using MethPrimer. Further, SNVs at CpG sites were accessed from NCBI, Ensembl while transcription factor (TF) binding sites were accessed using AliBaba2.1. CGI existence and size were determined for each SNV at CpG site with respect to wild type and variant allele by MethPrimer. A total of 200 SNVs at CpG sites were analyzed from the promoters of ACAT1, APOB, APOE, CYBA, FAS, FLT1, KSR2, LDLR, MMP9, PCSK9, PHOX2A, REST, SH2B3, SORT1 and TIMP1 genes. Of these, only 17 (8.5%) SNVs were found to influence the loss of CGI while 70 (35%) SNVs were found to reduce the size of CGI. It has also been found that 59% (10) of CGI abolishing SNVs are showing differences in binding of TFs. The findings of the study suggest that the candidate SNVs at CpG sites regulating CGI existence and size might influence the DNA methylation status and expression of genes involved in molecular pathways associated with several diseases. The insights of the present study may pave the way for new experimental studies to undertake challenges in DNA methylation, gene expression and protein assays.

Apoptosis in Type 2 Diabetes: Can It Be Prevented? Hippo Pathway Prospects

Diabetes mellitus is a heterogeneous disease of complex etiology and pathogenesis. Hyperglycemia leads to many serious complications, but also directly initiates the process of β cell apoptosis. A potential strategy for the preservation of pancreatic β cells in diabetes may be to inhibit the implementation of pro-apoptotic pathways or to enhance the action of pancreatic protective factors. The Hippo signaling pathway is proposed and selected as a target to manipulate the activity of its core proteins in therapy-basic research. MST1 and LATS2, as major upstream signaling kinases of the Hippo pathway, are considered as target candidates for pharmacologically induced tissue regeneration and inhibition of apoptosis. Manipulating the activity of components of the Hippo pathway offers a wide range of possibilities, and thus is a potential tool in the treatment of diabetes and the regeneration of β cells. Therefore, it is important to fully understand the processes involved in apoptosis in diabetic states and completely characterize the role of this pathway in diabetes. Therapy consisting of slowing down or stopping the mechanisms of apoptosis may be an important direction of diabetes treatment in the future.

Effect of kolaviron on islet dynamics in diabetic rats

Kolaviron, a biflavonoid isolated from the edible seeds of Garcinia kola, lowers blood glucose in experimental models of diabetes; however, the underlying mechanisms are not yet fully elucidated. The objective of the current study was to assess the effects of kolaviron on islet dynamics in streptozotocin-induced diabetic rats. Using double immunolabeling of glucagon and insulin, we identified insulin-producing β- and glucagon-producing α-cells in the islets of diabetic and control rats and determined the fractional β-cell area, α-cell area and islet number. STZ challenged rats presented with islet hypoplasia and reduced β-cell area concomitant with an increase in α-cell area. Kolaviron restored some islet architecture in diabetic rats through the increased β-cell area. Overall, kolaviron-treated diabetic rats presented a significant (p < 0.05) increase in the number of large and very large islets compared to diabetic control but no difference in islet number and α-cell area. The β-cell replenishment potential of kolaviron and its overall positive effects on glycemic control suggest that it may be a viable target for diabetes treatment.

Genetic association between major depressive disorder and type 2 diabetes mellitus: Shared pathways and protein networks

BACKGROUND

Major depressive disorder (MDD) and type 2 diabetes mellitus (T2DM) are common public health disorders that often co-occur. This study aims to determine whether gene expression profiles from individuals with MDD or T2DM overlap and if there are any functional interconnectivity between identified genes using protein-protein interaction (PPI).

METHODS

The DNA microarray datasets were extracted from the Gene Expression Omnibus. Gene expression dataset GSE98793 from a case-control study of MDD (64 healthy control subjects, 128 patients) and dataset GSE15653 from a case-control study of T2DM (nine controls, nine individuals with T2DM) were used for this secondary and post-hoc analysis. GO enrichment analyses and Reactome pathway enrichment analysis were performed for functional enrichment analyses with the shared genes. PPI networks, PPI clusters and hub genes were performed to detect the potential relationships among differentially expressed genes (DEG) -encoding proteins in both MDD and T2DM.

RESULTS

A total of 3640 DEGs were identified in the MDD group when compared to the control group, whereas 3700 DEGs were identified in the T2DM group when compared to the control groups, among which 244 DEGs were overlap genes. The identified DEGs were enriched for Interleukin-4 and Interleukin-13 signaling, neutrophil degranulation, as well as other select species of the innate immune system. The biological processes of neurofibrillary tangle assembly regulation, tau-protein kinase activity regulation, amyloid-beta clearance regulation, amyloid-beta formation regulation and neuron apoptotic processes were also identified. Molecular function analysis indicated that identified genes were mainly enriched for amyloid-beta binding. 925 out of 1006 protein-protein interactions and six sub-networks were identified reflecting the disparate biological domains of overlapping genes. Ten hub genes further highlight the putative importance of tau-protein kinase activity, inflammatory response and neuron apoptotic regulatory processes across MDD and T2DM.

CONCLUSIONS

Our results indicate that an overlapping genetic architecture subserves MDD and T2DM. Genes relevant to the innate immune system, tau protein formation, and cellular aging were identified. Results indicate that the common, often comorbid, conditions of MDD and T2DM have a pathoetiologic nexus.

Autophagy and apoptosis cascade: which is more prominent in neuronal death?

Autophagy and apoptosis are two crucial self-destructive processes that maintain cellular homeostasis, which are characterized by their morphology and regulated through signal transduction mechanisms. These pathways determine the fate of cellular organelle and protein involved in human health and disease such as neurodegeneration, cancer, and cardiovascular disease. Cell death pathways share common molecular mechanisms, such as mitochondrial dysfunction, oxidative stress, calcium ion concentration, reactive oxygen species, and endoplasmic reticulum stress. Some key signaling molecules such as p53 and VEGF mediated angiogenic pathway exhibit cellular and molecular responses resulting in the triggering of apoptotic and autophagic pathways. Herein, based on previous studies, we describe the intricate relation between cell death pathways through their common genes and the role of various stress-causing agents. Further, extensive research on autophagy and apoptotic machinery excavates the implementation of selective biomarkers, for instance, mTOR, Bcl-2, BH3 family members, caspases, AMPK, PI3K/Akt/GSK3β, and p38/JNK/MAPK, in the pathogenesis and progression of neurodegenerative diseases. This molecular phenomenon will lead to the discovery of possible therapeutic biomolecules as a pharmacological intervention that are involved in the modulation of apoptosis and autophagy pathways. Moreover, we describe the potential role of micro-RNAs, long non-coding RNAs, and biomolecules as therapeutic agents that regulate cell death machinery to treat neurodegenerative diseases. Mounting evidence demonstrated that under stress conditions, such as calcium efflux, endoplasmic reticulum stress, the ubiquitin-proteasome system, and oxidative stress intermediate molecules, namely p53 and VEGF, activate and cause cell death. Further, activation of p53 and VEGF cause alteration in gene expression and dysregulated signaling pathways through the involvement of signaling molecules, namely mTOR, Bcl-2, BH3, AMPK, MAPK, JNK, and PI3K/Akt, and caspases. Alteration in gene expression and signaling cascades cause neurotoxicity and misfolded protein aggregates, which are characteristics features of neurodegenerative diseases. Excessive neurotoxicity and misfolded protein aggregates lead to neuronal cell death by activating death pathways like autophagy and apoptosis. However, autophagy has a dual role in the apoptosis pathways, i.e., activation and inhibition of the apoptosis signaling. Further, micro-RNAs and LncRNAs act as pharmacological regulators of autophagy and apoptosis cascade, whereas, natural compounds and chemical compounds act as pharmacological inhibitors that rescue neuronal cell death through inhibition of apoptosis and autophagic cell death.

MicroRNAs' role in the environment-related non-communicable diseases and link to multidrug resistance, regulation, or alteration

The discovery of microRNAs (miRNAs) 20 years ago has advocated a new era of "small molecular genetics." About 2000 miRNAs are present that regulate one third of the genome. MiRNA dysregulated expression arising as a response to our environment insult or stress or changes may contribute to several diseases, namely non-communicable diseases, including tumor growth. Their presence in body fluids, reflecting level alteration in various cancers, merit circulating miRNAs as the "next-generation biomarkers" for early-stage tumor diagnosis and/or prognosis. Herein, we performed a comprehensive literature search focusing on the origin, biosynthesis, and role of miRNAs and summarized the foremost studies centering on miR value as non-invasive biomarkers in different environment-related non-communicable diseases, including various cancer types. Moreover, during chemotherapy, many miRNAs were linked to multidrug resistance, via modulating numerous, environment triggered or not, biological processes and/or pathways that will be highlighted as well.

Urolithin A, a pomegranate metabolite, protects pancreatic β cells from apoptosis by activating autophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Urolithin A is an active metabolite of plant polyphenol ellagic acid generated by intestinal flora, which is derived from strawberry or traditional anti-diabetic Chinese medicine such as Punica granatum L. and Phyllanthus emblica. The present study aimed to whether urolithin A can protect against glycolipid-toxicity-induced apoptosis of pancreatic β-cells and the underlying mechanisms.

MATERIALS AND METHODS

Apoptosis was induced in the pancreas of mice with type 2 diabetes and MIN6 pancreatic β-cells. CC-8 assay was conducted to determine cell viability. Flow cytometry, JC-1 fluorescent probe, and western blot assays were performed to assess apoptosis. Immunofluorescence and western blot assays were used to detect changes in autophagy. The mechanism of apoptosis was elucidated using autophagy inhibitor chloroquine.

RESULTS

Urolithin A intervention significantly reduced pancreatic cell apoptosis in diabetic mice and MIN6 β cells. This was achieved by the downregulation of cleaved-caspase 3, cleaved-caspase 1, and restoration of cell viability, cell morphology and mitochondrial membrane potential, accompanied with the downregulation of autophagic protein SQSTM1/p62 and upregulation of LC3II. Chloroquine, an autophagy inhibitor, reversed the anti-glucolipotoxic and anti-apoptotic effects of urolithin A.

CONCLUSION

These findings suggest that urolithin A protects against glucolipotoxicity-induced apoptosis in pancreatic β-cells by inducing activation of autophagy.

4-Methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene, a Major Active Metabolite of Bisphenol A, Triggers Pancreatic β-Cell Death via a JNK/AMPKα Activation-Regulated Endoplasmic Reticulum Stress-Mediated Apoptotic Pathway

4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), a major active metabolite of bisphenol A (BPA), is generated in the mammalian liver. Some studies have suggested that MBP exerts greater toxicity than BPA. However, the mechanism underlying MBP-induced pancreatic β-cell cytotoxicity remains largely unclear. This study demonstrated the cytotoxicity of MBP in pancreatic β-cells and elucidated the cellular mechanism involved in MBP-induced β-cell death. Our results showed that MBP exposure significantly reduced cell viability, caused insulin secretion dysfunction, and induced apoptotic events including increased caspase-3 activity and the expression of active forms of caspase-3/-7/-9 and PARP protein. In addition, MBP triggered endoplasmic reticulum (ER) stress, as indicated by the upregulation of GRP 78, CHOP, and cleaved caspase-12 proteins. Pretreatment with 4-phenylbutyric acid (4-PBA; a pharmacological inhibitor of ER stress) markedly reversed MBP-induced ER stress and apoptosis-related signals. Furthermore, exposure to MBP significantly induced the protein phosphorylation of JNK and AMP-activated protein kinase (AMPK)α. Pretreatment of β-cells with pharmacological inhibitors for JNK (SP600125) and AMPK (compound C), respectively, effectively abrogated the MBP-induced apoptosis-related signals. Both JNK and AMPK inhibitors also suppressed the MBP-induced activation of JNK and AMPKα and of each other. In conclusion, these findings suggest that MBP exposure exerts cytotoxicity on β-cells via the interdependent activation of JNK and AMPKα, which regulates the downstream apoptotic signaling pathway.

β cell aging and age-related diabetes

Type 2 diabetes is characterized by insulin resistance and loss of β cell mass and function. Aging is considered as a major risk factor for development of type 2 diabetes. However, the roles of pancreatic β cell senescence and systemic aging in the pathogenesis of type 2 diabetes in elderly people remain poorly understood. In this review, we aimed to discuss the current findings and viewpoints focusing on β cell aging and the development of type 2 diabetes.

The effect of diazinon on blood glucose homeostasis: a systematic and meta-analysis study

Though evidence exists on the association between diazinon (DZN), an organophosphate pesticide, with hyperglycemia, contrasting reports also exist. Herein, we performed a systematic and meta-analysis study to address this issue. A systematic search was conducted in PubMed, Ovid Medline, Google Scholar, Scopus, and Web of Science up to April 5, 2020, searching for animal studies (rodents and fish) that assessed the impact of DZN on blood glucose concentration. The risk of bias was assessed by the SYRCLE's RoB scale. Once each article's quality was assessed, a random-effects meta-regression was used to pool the data into a meta-analysis. Heterogeneity between the studies was evaluated with the I square and Q test. Random-effect meta-analysis of 19 studies (I² = 90.5%, p < 0.001) indicated low heterogeneity between the studies. DZN significantly increased blood glucose levels in the exposed versus control groups (95% CI: 2.46-4.94; Z = 5.86; p < 0.001). Subgroup analysis indicated that the effect of high-dose (3.40 (95% CI: 2.03-4.76)) DZN on changes in blood glucose was more pronounced than in the low dose (4.83 (95% CI: 1.56-8.11)). It was also ascertained that the blood glucose level was significantly higher in females (3.55 (95% CI: 2.21-4.89)) versus males (4.87 (95% CI: 0.20-9.55)) exposed to DZN. No publication bias was observed. Sensitivity analysis showed the robustness of the (standardized mean differences: 3.26-4.03). Our findings establish an association between DZN exposure and hyperglycemia in rodents and fish, which is both dose- and gender-dependent.

Gene Expression Profiling of Apoptotic Proteins in Circulating Peripheral Blood Mononuclear Cells in Type II Diabetes Mellitus and Modulation by Metformin

INTRODUCTION

Insulin resistance in obesity and type 2 diabetes mellitus (T2DM) is associated with cardiovascular complications such as atherosclerosis. On the other hand, the reduction of apoptosis in macrophages has been linked with accelerated atherosclerosis. Apoptosis is controlled by a different family of proteins including Bcl-2 and caspases.

METHODS

To examine apoptosis in insulin resistance, we assessed the mRNA expression by qRT-PCR of several Bcl-2 family members, as well as caspase-3, -7, -8, and -9 in peripheral blood mononuclear cells (PBMCs) isolated from lean, obese, diabetic, and diabetic on metformin individuals.

RESULTS

PBMCs of diabetic individuals exhibited reduced expression of caspase-7 and increased expression of Bcl-10, Bad, Bax, Bid, and caspase-3. T2DM on metformin group had significantly higher Bad, Bax, and caspase-7 expression.

DISCUSSION

The moderate up-regulation of pro-apoptotic Bcl-10, Bax, Bad, Bid, and the effector caspase-3 coupled with inhibition of caspase-7 in circulating PBMCs of T2DM could be the result of increased inflammation in T2DM. Metformin treatment significantly inhibited the expression of Bcl-10, Bid, and caspase-3 and upregulated Bad/Bax/caspase-7 pathway suggesting the activation of Bad/Bax/caspase-7 apoptotic pathway. Further studies are warranted to elicit the underlying apoptotic pathways of PBMCs in T2DM and following metformin treatment.

Antioxidant and Anti-inflammatory Properties of Yttrium Oxide Nanoparticles: New Insights into Alleviating Diabetes

BACKGROUND

Diabetes mellitus is a metabolic disease that requires immediate attention. Oxidative stress that leads to the generation of reactive oxygen species is a contributing factor to the disease progression. Yttrium oxide nanoparticles (Y₂O₃ NPs) have a profound effect on alleviating oxidative damage.

METHODS

The literature related to Y₂O₃ NPs and oxidative stress has been thoroughly searched using PubMed and Scopus databases and relevant studies from inception until August 2020 were included in this scoping review.

RESULTS

Y₂O₃ NPs altered oxidative stress-related biochemical parameters in different disease models including diabetes.

CONCLUSION

Although Y₂O₃ NPs are a promising antidiabetic agent due to their antioxidant and anti- inflammatory properties, more studies are required to further elucidate the pharmacological and toxicological properties of these nanoparticles.

Histone Deacetylase 3 Aggravates Type 1 Diabetes Mellitus by Inhibiting Lymphocyte Apoptosis Through the microRNA-296-5p/Bcl-xl Axis

Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease characterized by immune-mediated destruction of pancreatic beta-cells. Multiple microRNAs (miRNAs) have been implicated in T1DM pathogenesis. Although histone deacetylase 3 (HDAC3) has been reported to be involved in T1DM, the underlying mechanisms remain to be further elucidated. This study was designed to investigate the potential regulatory role of Hdac3 on T1DM progression. The expression of miR-296-5p and B-cell leukemia-XL (BCL-XL) was determined using RT-qPCR and Western blot assay in peripheral blood mononuclear cells (PBMCs) of patients with T1DM, tumor necrosis factor-α (TNF-α)- and cycloheximide (CHX)-induced cell model, and streptozotocin (STZ)-induced rat model. The binding affinity between miR-296-5p and Bcl-xl was verified by using dual-luciferase reporter gene assay, and the binding between Hdac3 and the promoter region of miR-296-5p was validated using chromatin immunoprecipitation assay. Western blot analysis and flow cytometry were conducted to assess the apoptotic events of lymphocytes. miR-296-5p expression was downregulated while BCL-XL expression was upregulated in PBMCs of patients with T1DM. An adverse correlation was identified between miR-296-5p and Bcl-xl in mouse TE15 B lymphocytes. Bcl-xl was further validated to be targeted and negatively regulated by miR-296-5p in 293 T cells. Hdac3 inhibited miR-296-5p expression by binding to its promoter region. The effects of overexpressed Hdac3 on lymphocyte apoptosis was counterweighed via downregulation of Bcl-xl or upregulation of miR-296-5p, the mechanism of which was further validated in a rat model of DM. Taken together, the Hdac3-mediated upregulation of Bcl-xl via inhibiting miR-296-5p promoter activity enhanced the anti-apoptotic capacity of lymphocytes to accelerate the occurrence of T1DM.

The effects of synthetic orally administrated insulin nanoparticles in comparison to injectable insulin on the renal function markers of type 1- diabetic rats

OBJECTIVES

Injectable insulin is the most widely used therapy in patients with type 1 diabetes which has several disadvantages. The present study was aimed to evaluate the efficacy of injectable insulin on diabetes mellitus-related complications in comparison to orally encapsulated insulin nanoparticles.

MATERIALS AND METHODS

This study involved 42 Wistar rats separated into 5 groups, including control (C), diabetic control (D), diabetic receiving regular insulin (INS), diabetic receiving encapsulated insulin nanoparticle (INP), and diabetic receiving chitosan for two months. Biochemical parameters in serum and urine were measured using spectrophotometric or ELISA methods. mRNA levels of kidney injury molecule 1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated using quantitative PCR.

RESULTS

There were no significant differences between the two forms of insulin in controlling the glycemic condition (P-value>0.05), but oral INP was more effective in correcting diabetic dyslipidemia in comparison to injectable insulin (P-value<0.05). Urine volume and creatinine excretion were significantly modulated by insulin and oral INP in diabetic groups (P-value<0.05), although the effects of INP on the modulation of execration of urea, acid uric, and albumin was more dramatic. Oral INP caused a significant decrease in urine concentration of KIM-1 and NGAL as well as expression of KIM-1 in renal tissue (P-value<0.05).

CONCLUSION

Our results suggested that oral INP is more effective than injectable insulin in modulation of urine and serum diabetic-related parameters.

Impact of chlorpyrifos on blood glucose concentration in an animal model: a systematic review and meta-analysis

Chlorpyrifos, an organophosphate insecticide, disturbs blood glucose hemostasis in experimental models and causes metabolic disorders. However, there are controversial findings of its impact on the BS level. The present meta-analysis aimed to investigate blood gluocse levels in rats exposed to chlorpyrifos. Present systematic review and meta-analysis study was done by searching in the online databases, including Google Scholar, Web of Science, PubMed, and Scopus. Data were analyzed by performing "random effects meta-regression." Findings were expressed as standardized mean value and 95% confidence interval (CI). Heterogeneity between studies was assessed using I-square and Q test. Meta-analysis of 7 animal studies indicated the dose-dependence manner of chlorpyrifos exposure on the blood glucose levels. The subgroup analysis indicated that exposure to low doses of chlorpyrifos significantly increased the blood glucose levels in exposed animals versus the nonexposed (0.11; 95% CI: - 1.14, 1.36, z = 2.25, p = 0.03, I2 = 90.1%, p < 0.001) and high doses markedly decreased blood glucose levels in exposed rats versus the nonexposed (7.34; 95%CI: - 9.35, - 5.32, z = 6.41, p < 0.001, I2 = 96.9%, p < 0.001). The random effects and pooled analysis indicated that the blood glucose levels were 4.22-fold lower in exposed animals versus the nonexposed ones (95% CI: - 5.59,- 2.85; Z = 3.97; p < 0.001); therefore, heterogeneity was significant (I2 = 96.5%, p < 0.001). The present finding indicated the association between chlorpyrifos exposure and a decrease in blood glucose levels. However, more studies should be designed to clarify this effect of chlorpyrifos exposure on blood glucose levels and involved mechanisms.

Design, synthesis and biological evaluation of vincamine derivatives as potential pancreatic β-cells protective agents for the treatment of type 2 diabetes mellitus

A series of vincamine derivatives were designed, synthesized and evaluated as pancreatic β-cells protective agents for type 2 diabetes mellitus. Most of the compounds displayed potent pancreatic β-cells protective activities and five derivatives were found to exhibit 20-50-fold higher activities than vincamine. Especially for compounds Vin-C01 and Vin-F03, exhibited a remarkable EC₅₀ value of 0.22 μM and 0.27 μM, respectively. Their pancreatic β-cells protective activities increased approximately 2 times than vincamine. In cell viability assay, compounds Vin-C01 and Vin-F03 could effectively promote β-cell survival and protect β-cells from STZ-induced apoptosis. Further cellular mechanism of action studies demonstrated that their potent β-cells protective activities were achieved by regulating IRS2/PI3K/Akt signaling pathway. The present study evidently showed that compounds Vin-C01 and Vin-F03 were two more potent pancreatic β-cells protective agents compared to vincamine and might serve as promising lead candidates for the treatment of type 2 diabetes mellitus.

Butyrolactone-I, an efficient α-glucosidase inhibitor, improves type 2 diabetes with potent TNF-α-lowering properties through modulating gut microbiota in db/db mice

The aim of this study was to evaluate the effects of butyrolactone-I (A6) on type 2 diabetes (T2D) in db/db mice because A6 was found to inhibit α-glucosidase activities and TNF-α release, which were associated with improving T2D. Male db/db mice were divided into 6 groups and given an equivalent volume of olive oil, acarbose, or different doses of A6 for 4 wk (n = 8/group). In this study, 11 butenolide derivatives were screened for their α-glucosidase and TNF-α suppressive activity in vitro. A6, an efficient α-glucosidase inhibitor, exerts hypoglycemic and multiple activities in reducing weight, improving glucose tolerance and insulin resistance, increasing short-chain fatty acid (SCFA) levels, activating SCFA-induced increases in glucagon-like peptide 1 and peroxisome proliferator-activated receptor-γ expression, enhancing intestinal mucosal barrier function and mitigating endoxemia in db/db mice. These effects may result from mediation of gut microbiota by A6. Meanwhile, A6, with potent TNF-α-lowering properties, was demonstrated to have multiple salutary effects with excellent structural stability and long-term safety in vivo. A6, an effective α-glucosidase inhibitor with high security and stability, exerted potent antidiabetic effects in vivo. Furthermore, the modulation of gut microbiota of A6 was demonstrated to be one of the mechanisms contributing to anti-inflammation properties and improving endoxemia. Our work confirms that the compound A6 is a prospective drug candidate for T2D.-Wu, W., Liu, L., Zhu, H., Sun, Y., Wu, Y., Liao, H., Gui, Y., Li, L., Liu, L., Sun, F., Lin, H. Butyrolactone-I, an efficient α-glucosidase inhibitor, improves type 2 diabetes with potent TNF-α-lowering properties through modulating gut microbiota in db/db mice.

Paraoxonase-1 as a Regulator of Glucose and Lipid Homeostasis: Impact on the Onset and Progression of Metabolic Disorders

Metabolic disorders are characterized by an overall state of inflammation and oxidative stress, which highlight the importance of a functional antioxidant system and normal activity of some endogenous enzymes, namely paraoxonase-1 (PON1). PON1 is an antioxidant and anti-inflammatory glycoprotein from the paraoxonases family. It is mainly expressed in the liver and secreted to the bloodstream, where it binds to HDL. Although it was first discovered due to its ability to hydrolyze paraoxon, it is now known to have an antiatherogenic role. Recent studies have shown that PON1 plays a protective role in other diseases that are associated with inflammation and oxidative stress, such as Type 1 and Type 2 Diabetes Mellitus and Non-Alcoholic Fatty Liver Disease. The aim of this review is to elucidate the physiological role of PON1, as well as the impact of altered PON1 levels in metabolic disorders.

The unconventional role of Akt1 in the advanced cancers and in diabetes-promoted carcinogenesis

Decades of research have elucidated the critical role of Akt isoforms in cancer as pro-tumorigenic and metastatic regulators through their specific effects on the cancer cells, tumor endothelial cells and the stromal cells. The pro-cancerous role of Akt isoforms through enhanced cell proliferation and suppression of apoptosis in cancer cells and the cells in the tumor microenvironment is considered a dogma. Intriguingly, studies also indicate that the Akt pathway is essential to protect the endothelial-barrier and prevent aberrant vascular permeability, which is also integral to tumor perfusion and metastasis. To complicate this further, a flurry of recent reports strongly indicates the metastasis suppressive role of Akt, Akt1 in particular in various cancer types. These reports emanated from different laboratories have elegantly demonstrated the paradoxical effect of Akt1 on cancer cell epithelial-to-mesenchymal transition, invasion, tumor endothelial-barrier disruption, and cancer metastasis. Here, we emphasize on the specific role of Akt1 in mediating tumor cell-vasculature reciprocity during the advanced stages of cancers and discuss how Akt1 differentially regulates cancer metastasis through mechanisms distinct from its pro-tumorigenic effects. Since Akt is integral for insulin signaling, endothelial function, and metabolic regulation, we also attempt to shed some light on the specific effects of diabetes in modulating Akt pathway in the promotion of tumor growth and metastasis.

Effects of novel antidiabetes agents on apoptotic processes in diabetes and malignancy: Implications for lowering tissue damage

Apoptosis is a complicated process that involves activation of a series of intracellular signaling. Tissue injuries from diabetes mellitus mostly occur as a consequence of higher rate of apoptosis process due to activation of a series of molecular mechanisms. Several classes of anti-hyperglycaemic agents have been developed which could potentially modulate the apoptotic process resulting in fewer tissue damages. Novel types of anti-hyperglycaemic medications such as sodium glucose cotransporters-2 inhibitors, glucagon like peptide-1 receptor agonists and dipeptidyl peptidase 4 inhibitors have shown to provide potent anti-hyperglycaemic effects, but their influences on diabetes-induced apoptotic injuries is largely unknown. Therefore, in the current study, we reviewed the published data about the possible effects of these anti-hyperglycaemic agents on apoptosis in diabetic milieu as well as in cancer cells.

NLRP3 inflammasome mediates angiotensin II-induced islet β cell apoptosis

Elevation of angiotensin II (Ang II) in the serum of patients with diabetes is known to promote apoptosis of islet β cells, but the underlying mechanism remains unclear. The aim of the present study was to explore the role of Nod-like receptor protein 3 (NLRP3) inflammasome in Ang II-induced apoptosis of pancreatic islet β cells and investigate the possible underlying mechanism. The effect of Ang II on INS-1 cell (a rat insulinoma cell line) viability was detected by CCK-8 method. The cell apoptosis was detected by flow cytometry and western blot analysis. The effect of Ang II on the expressions of thioredoxin-interacting protein (TXNIP) and NLRP3 protein was detected by western blot analysis. The expression of TXNIP mRNA was detected by real-time polymerase chain reaction. The results showed that Ang II was able to reduce INS-1 cell viability and promote apoptosis and at the same time up-regulate the expressions of TXNIP and NLRP3 components. Ang II-induced apoptosis was inhibited after administration of the NLRP3 inhibitor MCC950, and TXNIP silencing could reduce the NLRP3 expression and apoptosis, while both effects of Ang II on TXNIP-NLRP3 and its apoptosis-inducing effect were inhibited by angiotensin II type I receptor (AT1R) blocker Telmisartan. Our results demonstrated that the TXNIP-NLRP3 inflammasome pathway mediated Ang II-induced INS-1 cell apoptosis and might hopefully become a novel target for the treatment of diabetes mellitus.

Vincamine as a GPR40 agonist improves glucose homeostasis in type 2 diabetic mice

Vincamine, a monoterpenoid indole alkaloid extracted from the Madagascar periwinkle, is clinically used for the treatment of cardio-cerebrovascular diseases, while also treated as a dietary supplement with nootropic function. Given the neuronal protection of vincamine and the potency of β-cell amelioration in treating type 2 diabetes mellitus (T2DM), we investigated the potential of vincamine in protecting β-cells and ameliorating glucose homeostasis in vitro and in vivo. Interestingly, we found that vincamine could protect INS-832/13 cells function by regulating G-protein-coupled receptor 40 (GPR40)/cAMP/Ca2+/IRS2/PI3K/Akt signaling pathway, while increasing glucose-stimulated insulin secretion (GSIS) by modulating GPR40/cAMP/Ca2+/CaMKII pathway, which reveals a novel mechanism underlying GPR40-mediated cell protection and GSIS in INS-832/13 cells. Moreover, administration of vincamine effectively ameliorated glucose homeostasis in either HFD/STZ or db/db type 2 diabetic mice. To our knowledge, our current work might be the first report on vincamine targeting GPR40 and its potential in the treatment of T2DM.

MicroRNA-125b-5p improves pancreatic β-cell function through inhibiting JNK signaling pathway by targeting DACT1 in mice with type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a progressive disease, accompanied by increased insulin resistance and deteriorating β-cell function. Previous studies have revealed that microRNA (miRNA) plays a crucial role in the treatment of T2DM. Hence, we aim to investigate the role of microRNA-125b-5p (miR-125b-5p) in pancreatic β-cell function and insulin sensitivity of mice with T2DM with the involvement of Dishevelled antagonist Dapper1 (DACT1) and the c-Jun NH2-terminal kinases (JNK) signaling pathway. Firstly, a mouse model of T2DM was established by administering a high-fat diet plus low dosage of streptozotocin, and function of pancreatic β-cell and insulin sensitivity in the normal and T2DM mice were detected. Then, the pancreatic β-cells were collected from pancreatic islet tissues and treated with different mimics, inhibitors and siRNAs. After that, the relationship among miR-125b-5p, DACT1, and the JNK signaling-related factors in T2DM mice was determined. Finally, cell proliferation and apoptosis were determined. Mice with T2DM had lower pancreatic β-cell function and insulin sensitivity, as well as diminished expression of miR-125b-5p but enhanced expressions of DACT1, JNK and c-Jun. miR-125b-5p inhibited DACT1 expression and the activation of the JNK signaling pathway, as well as restrained cell proliferation and promoted cell apoptosis. The current results suggest that up-regulated miR-125b-5p promotes insulin sensitivity and enhances pancreatic β-cell function through inhibiting the JNK signaling pathway by negatively mediating DACT1.

PTEN inhibitor VO-OHpic attenuates inflammatory M1 macrophages and cardiac remodeling in doxorubicin-induced cardiomyopathy

Doxorubicin (Doxo) is an effective agent commonly used in cancer therapeutics. Unfortunately, Doxo treatment can stimulate cardiomyopathy and subsequent heart failure, limiting the use of this drug. The role of phosphatase and tensin homolog (PTEN) in apoptosis has been documented in Doxo-induced cardiomyopathy (DIC) and heart failure models. However, whether direct inhibition of PTEN attenuates apoptosis, cardiac remodeling, and inflammatory M1 macrophages in the DIC model remains elusive. Therefore, the present study was designed to understand the effects of VO-OHpic (VO), a potent inhibitor of PTEN, in reducing apoptosis and cardiac remodeling. At day 56, echocardiography was performed, which showed that VO treatment significantly ( P < 0.05) improved heart function. Immunohistochemistry, TUNEL, and histological staining were used to determine apoptosis, proinflammatory M1 macrophages, anti-inflammatory M2 macrophages, and cardiac remodeling. Our data show a significant increase in apoptosis, hypertrophy, fibrosis, and proinflammatory M1 macrophages with Doxo treatment, whereas VO treatment significantly reduced apoptosis, adverse cardiac remodeling, and proinflammatory M1 macrophages significantly ( P < 0.05) compared with the Doxo-treated group. Western blot analysis confirmed the reduction of phosphorylated PTEN and increase in phosphorylated AKT protein expression in the Doxo + VO-treated group. Moreover, VO administration increased anti-inflammatory M2 macrophages. Collectively, our data suggest that VO treatment attenuates apoptosis and adverse cardiac remodeling, a process that is mediated through the PTEN/AKT pathway, resulting in improved heart function in DIC. NEW & NOTEWORTHY Doxorubicin-induced cardiomyopathy (DIC) is still a major issue in patients with cancer. These novel findings on the phosphatase and tensin homolog inhibitor VO-OHpic in DIC is the first report, as per the best of our knowledge, that VO-OHpic significantly decreases apoptosis, fibrosis, hypertrophy, adverse cardiac remodeling, and proinflammatory M1 macrophages and increases anti-inflammatory M2 macrophages along with significantly improved cardiac function. VO-OHpic could be a future therapeutic agent for patients with DIC.

MicroRNAs and type 2 diabetes mellitus: Molecular mechanisms and the effect of antidiabetic drug treatment

The incidence of type 2 diabetes mellitus (T2DM), the most prevalent metabolic disease, is rapidly growing worldwide. T2DM has several underlying causes involved in its development. In recent decades, there is compelling evidence demonstrating that microRNAs (miRs) are implicated in the pathophysiology of T2DM. miRs are small non-coding RNAs which serve as endogenous gene regulators by binding to specific sequences in RNA and modifying gene expression toward up- or down-regulation. T2DM occurrence and complications may be influenced by increasing or decreasing the activity of some miRs. In the present narrative review, we comment on four molecular pathways/mechanisms that mediate the link between T2DM and different forms of miRs. These mechanisms include involvement of miRs in beta cells development, insulin sensitivity/resistance, insulin production/secretion and insulin signaling. The effects of antidiabetic drugs on miRs are also discussed.

Anti-apoptotic activity of human matrix metalloproteinase-2 attenuates diabetes mellitus

BACKGROUND

Chronic progression of diabetes is associated with decreased pancreatic islet mass due to apoptosis of β-cells. Patients with diabetes have increased circulating matrix metalloproteinase-2 (MMP2); however, the physiological significance has remained elusive. This study tested the hypothesis that MMP2 inhibits cell apoptosis, including islet β-cells.

METHODS

Samples from diabetic patients and newly developed transgenic mice overexpressing human MMP2 (hMMP2) were harnessed, and diabetes was induced with streptozotocin.

RESULTS

Circulating hMMP2 was significantly increased in diabetic patients compared to controls and significantly correlated with the serum C-peptide levels. The diabetic hMMP2 transgenic mice showed significant improvements in glycemia, glucose tolerance and insulin secretion compared to diabetic wild type mice. Importantly, the increased hMMP2 levels in mice correlated with significant reduction in islet β-cell apoptosis compared to wild-type counterparts, and an inhibitor of hMMP2 reversed this mitigating activity against diabetes. The increased activation of Akt and BAD induced by hMMP2 in β-cells compared to controls, links this signaling pathway to the anti-apoptotic activity of hMMP2, a property that was reversible by both an hMMP2 inhibitor and antibody against integrin-β3.

CONCLUSION

Overall, this study demonstrates that increased expression of hMMP2 may attenuate the severity of diabetes by protecting islet β-cells from apoptosis through an integrin-mediated activation of the Akt/BAD pathway.

Signaling mediators modulated by cardioprotective interventions in healthy and diabetic myocardium with ischaemia-reperfusion injury

Ischaemic heart diseases are one of the major causes of death in the world. In most patients, ischaemic heart disease is coincident with other risk factors such as diabetes. Patients with diabetes are more prone to cardiac ischaemic dysfunctions including ischaemia-reperfusion injury. Ischaemic preconditioning, postconditioning and remote conditionings are reliable interventions to protect the myocardium against ischaemia-reperfusion injuries through activating various signaling pathways and intracellular mediators. Diabetes can disrupt the intracellular signaling cascades involved in these myocardial protections, and studies have revealed that cardioprotective effects of the conditioning interventions are diminished in the diabetic condition. The complex pathophysiology and poor prognosis of ischaemic heart disease among people with diabetes necessitate the investigation of the interaction of diabetes with ischaemia-reperfusion injury and cardioprotective mechanisms. Reducing the outcomes of ischaemia-reperfusion injury using targeted strategies would be particularly helpful in this population. In this study, we review the protective interventional signaling pathways and mediators which are activated by ischaemic conditioning strategies in healthy and diabetic myocardium with ischaemia-reperfusion injury.

Effects of exposure to malathion on blood glucose concentration: a meta-analysis

Exposure to malathion (an organophosphate pesticide widely used around the world) has been associated with alterations in blood glucose concentration in animal models. However, the results are inconsistent. The aim of this meta-analysis was to evaluate whether malathion exposure can disturb the concentrations of blood glucose in exposed rats. We performed a literature search of online databases including PubMed, EBSCO, and Google Scholar and reviewed original articles that analyzed the relation between malathion exposure and glucose levels in animal models. The selection of articles was based on inclusion and exclusion criteria. The database search identified thirty-five possible articles, but only eight fulfilled our inclusion criteria, and these studies were included in the meta-analysis. The effect of malathion on blood glucose concentration showed a non-monotonic dose-response curve. In addition, pooled analysis showed that blood glucose concentrations were 3.3-fold higher in exposed rats than in the control group (95% CI, 2-5; Z = 3.9; p < 0.0001) in a random-effect model. This result suggested that alteration of glucose homeostasis is a possible mechanism of toxicity associated with exposure to malathion.

Identification of key gene pathways and coexpression networks of islets in human type 2 diabetes

PURPOSE

The number of people with type 2 diabetes (T2D) is growing rapidly worldwide. Islet β-cell dysfunction and failure are the main causes of T2D pathological processes. The aim of this study was to elucidate the underlying pathways and coexpression networks in T2D islets.

MATERIALS AND METHODS

We analyzed the differentially expressed genes (DEGs) in the data set GSE41762, which contained 57 nondiabetic and 20 diabetic samples, and developed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Protein-protein interaction (PPI) network, the modules from the PPI network, and the gene annotation enrichment of modules were analyzed as well. Moreover, a weighted correlation network analysis (WGCNA) was applied to screen critical gene modules and coexpression networks and explore the biological significance.

RESULTS

We filtered 957 DEGs in T2D islets. Then GO and KEGG analyses identified that key pathways like inflammatory response, type B pancreatic cell differentiation, and calcium ion-dependent exocytosis were involved in human T2D. Three significant modules were filtered from the PPI network. Ribosome biogenesis, extrinsic apoptotic signaling pathway, and membrane depolarization during action potential were associated with the modules, respectively. Furthermore, coexpression network analysis by WGCNA identified 13 distinct gene modules of T2D islets and revealed four modules, which were strongly correlated with T2D and T2D biomarker hemoglobin A1c (HbA1c). Functional annotation showed that these modules mainly enriched KEGG pathways such as NF-kappa B signaling pathway, tumor necrosis factor signaling pathway, cyclic adenosine monophosphate signaling pathway, and peroxisome proliferators-activated receptor signaling pathway.

CONCLUSION

The results provide potential gene pathways and underlying molecular mechanisms for the prevention, diagnosis, and treatment of T2D.

Elevated Markers of Death Receptor-Activated Apoptosis are Associated with Increased Risk for Development of Diabetes and Cardiovascular Disease

Background

An increased rate of cell death by apoptosis has been implicated in both diabetes and atherosclerosis. Apoptosis can be induced through activation of the death receptors TNF receptor 1 (TNFR-1), TRAIL receptor 2 (TRAILR-2) and Fas. Soluble forms of these receptors are found in plasma. The objective of this study was to determine if soluble death receptors are markers of receptor-activated apoptosis and predict risk for development of diabetes and cardiovascular events.

Methods

Fas ligand was used to induce apoptosis in peripheral blood mononuclear cells and INS-1 pancreatic β-cells and release of TNFR-1, TRAILR-2 and Fas measured by ELISA. Proximity Extension Assay was used to analyze plasma levels of TNFR-1, TRAILR-2 and Fas in baseline samples of 4742 subjects in the Malmö Diet and Cancer Study and related to development of diabetes and cardiovascular events during 19.2 years of follow-up.

Results

Activation of apoptosis by Fas ligand was associated with release of soluble Fas, TNFR-1 and TRAILR-2 in both cell types. Circulating levels of all three receptors were higher in subjects with diabetes and correlated with markers of impaired glucose metabolism in non-diabetic subjects. Among the latter, those in the highest tertile of soluble Fas, TNFR-1 and TRAILR-2 had increased risk for development of diabetes and cardiovascular events. These associations became weaker when adjusting for cardiovascular risk factors in Cox regression models, but remained significant for TRAILR-2 with incident diabetes, cardiovascular mortality, myocardial infarction and ischemic stroke, and for TNFR-1 with myocardial infarction.

Conclusion

The present study demonstrates an association between several cardiovascular risk factors and elevated levels of circulating markers of apoptotic cell death. It also shows that subjects with high levels of these biomarkers have increased risk of diabetes and CVD. This implies that soluble death receptors are markers of β-cell and vascular injury and potentially could be used as surrogate markers of therapeutic efficiency in risk factor interventions.

•Receptor-activated apoptosis is associated with release of soluble death receptors that act as biomarkers of apoptosis •Several cardiovascular risk factors including markers of impaired glucose metabolism associate with elevated plasma levels of death receptors •Subjects with high plasma levels of death receptors have an increased risk of diabetes and cardiovascular disease

Atherosclerosis has been proposed to develop in response to chronic arterial injury caused by cardiovascular risk factors. The present study provides clinical evidence for this hypothesis by demonstrating an association between several cardiovascular risk factors and elevated levels of circulating markers of apoptotic cell death and that subjects with high levels of these biomarkers have increased risk of cardiovascular mortality, MI and stroke. These observations point to the possibility that the plasma level of soluble death receptors can be used as surrogate markers of arterial injury and atherosclerotic disease activity in cardiovascular interventions. Finally, our findings imply that soluble death receptors also may serve as biomarkers of the damage caused by metabolic stress to β-cells and risk for development of type 2 diabetes.

Autophagy and its link to type II diabetes mellitus

Autophagy, a double-edged sword for cell survival, is the research object on 2016 Nobel Prize in Physiology or Medicine. Autophagy is a molecular mechanism for maintaining cellular physiology and promoting survival. Defects in autophagy lead to the etiology of many diseases, including diabetes mellitus (DM), cancer, neurodegeneration, infection disease and aging. DM is a metabolic and chronic disorder and has a higher prevalence in the world as well as in Taiwan. The character of diabetes mellitus is hyperglycemia resulting from defects in insulin secretion, insulin action, or both. Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance and failure of producing insulin on pancreatic beta cells. In T2DM, autophagy is not only providing nutrients to maintain cellular energy during fasting, but also removes damaged organelles, lipids and miss-folded proteins. In addition, autophagy plays an important role in pancreatic beta cell dysfunction and insulin resistance. In this review, we summarize the roles of autophagy in T2DM.

A comparison of caspase 3 expression in the endocrine and exocrine parts of the pancreas after cladribine application according to the "leukemic" schema

The therapeutic effects of the immunosuppressive agent, cladribine, have been demonstrated by its toxicity to cells. However, its effects on healthy cells of the body is poorly understood. The aim of study was, hence, to, firstly, evaluate the morphology of the endocrine and exocrine pancreas after the administration of cladribine according to the "leukemic" schema, and, secondly, to assess its impact on the intensity of apoptosis. The experiment was carried out on female Wistar rats which were placed within the control group KA, and the experimental groups: A and A-bis. In the experimental groups, Cladribine was administered according to the cycle used to treat human hairy cell leukemia. In group A, the material was taken 24 hours after administration of the last dose of the drug, while in group A-bis, this was done after a 4 weeks break. The reaction was assessed to be average in 80% of all cells in group A, and in 64% of all acinar cells in group KA, while in group A-bis, the majority of the exocrine cells demonstrated a lack of immunohistochemical response (72%). Moreover, most endocrine cells (60%) in group A-bis revealed a strong reaction, while in Group A, the corresponding figure is a little over 34%. A comparison of the severity of the caspase 3 expression in both the exocrine and endocrine pancreas showed significant differentiation results between the group KA and group A-bis, and between group A and A-bis (p < 0.0001). In can be concluded that endocrine cells are more sensitive to cladribine than are exocrine cells.

A Randomized Controlled Trial Comparing the Effects of Sitagliptin and Glimepiride on Endothelial Function and Metabolic Parameters: Sapporo Athero-Incretin Study 1 (SAIS1)

Objectives

The DPP-4 inhibitors are incretin-related drugs that improve hyperglycemia in a glucose-dependent manner and have been reported to exert favorable effects on atherosclerosis. However, it has not been fully elucidated whether DPP-4 inhibitors are able to improve endothelial function in patients with type 2 diabetes. Therefore, we investigated the efficacy of sitagliptin, a DPP-4 inhibitor, on endothelial function and glycemic metabolism compared with that of the sulfonylurea glimepiride.

Materials and Methods

In this multicenter, prospective, randomized parallel-group comparison study, 103 outpatients with type 2 diabetes (aged 59.9 ± 9.9 years with HbA1c levels of 7.5 ± 0.4%) with dietary cure only and/or current metformin treatment were enrolled and randomly assigned to receive sitagliptin or glimepiride therapy once daily for 26 weeks. Flow-mediated dilation (FMD), a comprehensive panel of hemodynamic parameters (Task Force^® Monitor), and serum metabolic markers were assessed before and after the treatment.

Results

During the study period, no statistically significant change in %FMD was seen in both groups (sitagliptin, 5.6 to 5.6%; glimepiride, 5.6 to 6.0%). Secretory units of islets in transplantation, TNF-α, adiponectin and biological antioxidant potential significantly improved in the sitagliptin group, and superoxide dismutase also tended to improve in the sitagliptin group, while improvements in HbA1c levels were similar between groups. Cardiac index, blood pressure and most other metabolic parameters were not different.

Conclusions

Regardless of glycemic improvement, early sitagliptin therapy did not affect endothelial function but may provide favorable effects on beta-cell function and on inflammatory and oxidative stress in patients with type 2 diabetes without advanced atherosclerosis.

Trial Registration

UMIN Clinical Trials Registry System UMIN 000004955

Hormetic and regulatory effects of lipid peroxidation mediators in pancreatic beta cells

Nutrient sensing mechanisms of carbohydrates, amino acids and lipids operate distinct pathways that are essential for the adaptation to varying metabolic conditions. The role of nutrient-induced biosynthesis of hormones is paramount for attaining metabolic homeostasis in the organism. Nutrient overload attenuate key metabolic cellular functions and interfere with hormonal-regulated inter- and intra-organ communication, which may ultimately lead to metabolic derangements. Hyperglycemia and high levels of saturated free fatty acids induce excessive production of oxygen free radicals in tissues and cells. This phenomenon, which is accentuated in both type-1 and type-2 diabetic patients, has been associated with the development of impaired glucose tolerance and the etiology of peripheral complications. However, low levels of the same free radicals also induce hormetic responses that protect cells against deleterious effects of the same radicals. Of interest is the role of hydroxyl radicals in initiating peroxidation of polyunsaturated fatty acids (PUFA) and generation of α,β-unsaturated reactive 4-hydroxyalkenals that avidly form covalent adducts with nucleophilic moieties in proteins, phospholipids and nucleic acids. Numerous studies have linked the lipid peroxidation product 4-hydroxy-2E-nonenal (4-HNE) to different pathological and cytotoxic processes. Similarly, two other members of the family, 4-hydroxyl-2E-hexenal (4-HHE) and 4-hydroxy-2E,6Z-dodecadienal (4-HDDE), have also been identified as potential cytotoxic agents. It has been suggested that 4-HNE-induced modifications in macromolecules in cells may alter their cellular functions and modify signaling properties. Yet, it has also been acknowledged that these bioactive aldehydes also function as signaling molecules that directly modify cell functions in a hormetic fashion to enable cells adapt to various stressful stimuli. Recent studies have shown that 4-HNE and 4-HDDE, which activate peroxisome proliferator-activated receptor δ (PPARδ) in vascular endothelial cells and insulin secreting beta cells, promote such adaptive responses to ameliorate detrimental effects of high glucose and diabetes-like conditions. In addition, due to the electrophilic nature of these reactive aldehydes they form covalent adducts with electronegative moieties in proteins, phosphatidylethanolamine and nucleotides. Normally these non-enzymatic modifications are maintained below the cytotoxic range due to efficient cellular neutralization processes of 4-hydroxyalkenals. The major neutralizing enzymes include fatty aldehyde dehydrogenase (FALDH), aldose reductase (AR) and alcohol dehydrogenase (ADH), which transform the aldehyde to the corresponding carboxylic acid or alcohols, respectively, or by biding to the thiol group in glutathione (GSH) by the action of glutathione-S-transferase (GST). This review describes the hormetic and cytotoxic roles of oxygen free radicals and 4-hydroxyalkenals in beta cells exposed to nutritional challenges and the cellular mechanisms they employ to maintain their level at functional range below the cytotoxic threshold.

Functional genetics-directed identification of novel pharmacological inhibitors of FAS- and TNF-dependent apoptosis that protect mice from acute liver failure

shRNA-mediated gene-silencing technology paired with cell-based functional readouts reveals potential targets directly, providing an opportunity to identify drugs against the target without knowing the precise role of the target in the pathophysiological processes of interest. By screening a lentiviral shRNA library targeting for major components of human signaling pathways and known drug targets, we identified and validated both canonical as well as 52 novel mediators of FAS and TNF ligand-induced apoptosis. Presence of potential therapeutic targets among these mediators was confirmed by demonstration of in vivo activity of siRNAs against four identified target candidates that protected mice from acute liver failure (ALF), a life-threatening disease with known involvement of death receptor (DR)-mediated apoptosis. Network-based modeling was used to predict small-molecule inhibitors for several candidate apoptosis mediators, including somatostatin receptor 5 (SSTR5) and a regulatory subunit of PP2A phosphatase, PPP2R5A. Remarkably, pharmacological inhibition of either SSTR5 or PPP2R5A reduced apoptosis induced by either FASL or TNF in cultured cells and dramatically improved survival in several mouse models of ALF. These results demonstrate the utility of loss-of-function genetic screens and network-based drug-repositioning methods for expedited identification of targeted drug candidates and revealed pharmacological agents potentially suitable for treatment of DR-mediated pathologies.

Bariatric surgery: beta cells in type 2 diabetes remission

Bariatric surgery is a new emerging treatment that demonstrates a favourable effect on type 2 diabetes, although its underlying mechanisms still remain unknown. After receiving bariatric surgery, beta cells undergo the process of rebirth, which involves apoptosis evasion, regeneration and improved beta-cell function. Therefore, further studies are necessary to elucidate how bariatric surgery can resolve type 2 diabetes. Here, our review focuses mainly on beta cells, the insulin-generating cells, whose biological features change dramatically after bariatric surgery. Copyright © 2015 John Wiley & Sons, Ltd.

Thioredoxin-dependent regulation of AIF-mediated DNA damage

The thioredoxin (Trx) system is one major redox system in mammalian cells. One of its component, Trx, is involved in redox homeostasis and many cellular biological processes through participating in disulfide reduction, S-nitrosylation/S-denitrosylation reactions and protein-protein interactions. In this study, we report the identification of a novel interaction between cytosolic/nuclear Trx1 and apoptosis inducing factor (AIF), and the redox sensitivity and biological significance of the Trx-AIF interaction was characterized. Cytosolic Trx1 but not mitochondrial Trx2 was observed to interact with AIF under physiological conditions and Trx1's active site cysteines were crucial for the interaction. Under oxidative stress conditions, Trx-AIF interaction was disrupted. When the treated cells were allowed to recover from oxidative stress by means of removal of the oxidants, interaction between Trx1 and AIF was re-established time-dependently, which underpins the biological relevance of a Trx-dependent redox regulation of AIF-mediated cell death. Indeed, in times of oxidative stress, nuclear translocation of AIF was found to occur concurrently with perturbations to the Trx-AIF interaction. Once localized in the nucleus, reduced Trx1 hindered the interaction between AIF and DNA, thereby bringing about an attenuation of AIF-mediated DNA damage. In conclusion, characterization of the Trx-AIF interaction has led to an understanding of the effect of reduced Trx1 on possibly regulating AIF-dependent cell death through impeding AIF-mediated DNA damage. Importantly, identification of the novel interaction between Trx1 and AIF has provided opportunities to design and develop therapeutically relevant strategies that either promote or prevent this protein-protein interaction for the treatment of different disease states.

High-fat diet combined with low-dose streptozotocin injections induces metabolic syndrome in Macaca mulatta

Metabolic syndrome (MetS) is associated with abdominal obesity, hyperlipidemia, insulin resistance, and type 2 diabetes mellitus, and increases the risk of cardiovascular disease. Given the complex multifactorial pathogenesis of MetS, qualified animal models are currently seriously limited for researchers. The aim of our study was to develop a MetS model in juvenile rhesus monkeys (Macaca mulatta). Rhesus monkeys (1-year-old) fed a high-fat diet (15 % fat, 2 % cholesterol) were used as the HF group (n = 6), and those on a normal diet (5 % fat) were used as the control group (n = 4). After being fed a high-fat diet for approximately 12 months, 2 monkeys (HF + STZ group) were injected with low-dose streptozotocin (STZ, 25 mg/kg) twice, with a 7 days interval, and were then fed the same diet continuously for another 24 months. After 36 months of treatment, the high-fat diet monkeys, including the HF and HF + STZ groups, had acquired increased body weights, abnormal serum lipids, and impaired glucose tolerance compared to the control group. In addition, much more marked metabolic changes were observed in the two monkeys of the HF + STZ group, particularly in terms of high-blood glucose level and insulin resistance. Morphological observation of biopsies of liver and pancreatic tissues showed decreased islet number and mass and decreased insulin staining in the monkeys of the HF + STZ group. In addition, Oil red O staining suggested remarkable accumulation of lipid droplets in the hepatocytes. Our study suggested that a long-term high-fat diet followed with a low-dose STZ was able to induce MetS in juvenile rhesus monkeys with faster pathophysiological progress compared with high-fat diet induction alone. Our primary data showed that this method may have potentials to develop MetS animal model in non-human primates.