An update on preventive and regenerative therapies in diabetes mellitus

Revolutionizing Diabetes Care: The Role of Marine Bioactive Compounds and Microorganisms

Diabetes is a metabolic condition characterized by high blood glucose levels. Aquatic products like microalgae, bacteria, seagrasses, macroalgae, corals, and sponges have been investigated for potential anti-diabetic properties. We looked at polyphenols, peptides, pigments, and sterols, as well as other bioactive substances found in marine resources, to see if they could help treat or manage diabetes, in addition to describing the several treatment strategies that alter diabetes and its implications, such as inhibition of protein tyrosine phosphatases 1B (PTP1B), α-glucosidase, α-amylase, dipeptidyl peptidase IV (DPP-IV), aldose reductase, lipase, glycogen synthase kinase 3β (GSK-3β), and insulin resistance prevention, promotion of liver antioxidant capacity, natural killer cell stimulant, anti-inflammatory actions, increased AMP-activated protein kinase (AMPK) phosphorylation and sugar and metabolism of the lipid, reducing oxidative stress, and β-pancreatic cell prevention. This study highlights the revolutionary potential of marine bioactive compounds and microorganisms in transforming diabetes care. We believe in a future in which innovative, sustainable, and efficient therapeutic approaches will result in improved quality of life and better outcomes for people with diabetes mellitus by forging a new path for treatment, utilizing the power of the world's oceans, and capitalizing on the symbiotic relationship between humans and the marine ecosystem. This study area offers optimism and promising opportunities for transforming diabetes care.

Phthalimide as a versatile pharmacophore scaffold: Unlocking its diverse biological activities

Phthalimide, a pharmacophore exhibiting diverse biological activities, holds a prominent position in medicinal chemistry. In recent decades, numerous derivatives of phthalimide have been synthesized and extensively studied for their therapeutic potential across a wide range of health conditions. This comprehensive review highlights the latest developments in medicinal chemistry, specifically focusing on phthalimide-based compounds that have emerged within the last decade. These compounds showcase promising biological activities, including anti-inflammatory, anti-Alzheimer, antiepileptic, antischizophrenia, antiplatelet, anticancer, antibacterial, antifungal, antimycobacterial, antiparasitic, anthelmintic, antiviral, and antidiabetic properties. The physicochemical profiles of the phthalimide derivatives were carefully analyzed using the online platform pkCSM, revealing the remarkable versatility of this scaffold. Therefore, this review emphasizes the potential of phthalimide as a valuable scaffold for the development of novel therapeutic agents, providing avenues for the exploration and design of new compounds.

Deep-sea fungal metabolites as potential inhibitors of glucose-regulatory enzymes: In silico structure-activity analysis

Chronic diabetes mellites related hyperglycemia is a major cause of mortality and morbidity due to further complications like retinopathy, hypertension and cardiovascular diseases. Though several synthetic anti-diabetes drugs specifically targeting glucose-metabolism enzymes are available, they have their own limitations, including adverse side-effects. Unlike other natural or marine-derived pharmacologically important molecules, deep-sea fungi metabolites still remain under-explored for their anti-diabetes potential. We performed structure-based virtual screening of deep-sea fungal compounds selected by their physiochemical properties, targeting crucial enzymes viz., α -amylase, α -glucosidase, pancreatic-lipoprotein lipase, hexokinase-II and protein tyrosine phosphatase-1B involved in glucose-metabolism pathway. Following molecular docking scores and MD simulation analyses, the selected top ten compounds for each enzyme, were subjected to pharmacokinetics prediction based on their AdmetSAR- and pharmacophore-based features. Of these, cladosporol C, tenellone F, ozazino-cyclo-(2,3-dihydroxyl-trp-tyr), penicillactam and circumdatin G were identified as potential inhibitors of α -amylase, α -glucosidase, pancreatic-lipoprotein lipase, hexokinase-II and protein tyrosine phosphatase-1B, respectively. Our in silico data therefore, warrants further experimental and pharmacological studies to validate their anti-diabetes therapeutic potential.

Hypoglycaemic Molecules for the Management of Diabetes Mellitus from Marine Sources

Diabetes mellitus (DM) is a chronic metabolic disorder recognized as a major health problem globally. A defective insulin activity contributes to the prevalence and expansion of DM. Treatment of DM is often hampered by limited options of conventional therapies and adverse effects associated with existing procedures. This has led to a spike in the exploration for potential therapeutic agents from various natural resources for clinical applications. The marine environment is a huge store of unexplored diversity of chemicals produced by a multitude of organisms. To date, marine microorganisms, microalgae, macroalgae, corals, sponges, and fishes have been evaluated for their anti-diabetic properties. The structural diversity of bioactive metabolites discovered has shown promising hypoglycaemic potential through in vitro and in vivo screenings via various mechanisms of action, such as PTP1B, α-glucosidase, α-amylase, β-glucosidase, and aldose reductase inhibition as well as PPAR alpha/gamma dual agonists activities. On the other hand, hypoglycaemic effect is also shown to be exerted through the balance of antioxidants and free radicals. This review highlights marine-derived chemicals with hypoglycaemic effects and their respective mechanisms of action in the management of DM in humans.

Novel Potent and Selective DPP-4 Inhibitors: Design, Synthesis and Molecular Docking Study of Dihydropyrimidine Phthalimide Hybrids

BACKGROUND

Dipeptidyl peptidase-4 (DPP-4) inhibitors have emerged as anti-hyperglycemic agents that improve glycemic control in type 2 diabetic patients, either as monotherapy or in combination with other antidiabetic drugs.

METHODS

A novel series of dihydropyrimidine phthalimide hybrids was synthesized and evaluated for their in vitro and in vivo DPP-4 inhibition activity and selectivity using alogliptin as reference. Oral glucose tolerance test was assessed in type 2 diabetic rats after chronic treatment with the synthesized hybrids ± metformin. Cytotoxicity and antioxidant assays were performed. Additionally, molecular docking study with DPP-4 and structure activity relationship of the novel hybrids were also studied.

RESULTS

Among the synthesized hybrids, 10g, 10i, 10e, 10d and 10b had stronger in vitro DPP-4 inhibitory activity than alogliptin. Moreover, an in vivo DPP-4 inhibition assay revealed that 10g and 10i have the strongest and the most extended blood DPP-4 inhibitory activity compared to alogliptin. In type 2 diabetic rats, hybrids 10g, 10i and 10e exhibited better glycemic control than alogliptin, an effect that further supported by metformin combination. Finally, 10j, 10e, 10h and 10d had the highest radical scavenging activity in DPPH assay.

CONCLUSIONS

Hybrids 10g, 10i and 10e are potent DPP-4 inhibitors which may be beneficial for T2DM treatment.

Aloperine Relieves Type 2 Diabetes Mellitus via Enhancing GLUT4 Expression and Translocation

Aloperine (ALO), a quinolizidine alkaloid isolated from Sophora alopecuroides L. used in the traditional Uygur medicine, induced a significant increase in cellular glucose uptake of L6 cells, suggesting it has the potential to relieve hyperglycemia. Therefore, we investigated the effects of ALO on type 2 diabetes mellitus (T2DM) through in vitro and in vivo studies. The translocation of glucose transporter 4 (GLUT4) and changes in intracellular Ca²⁺ levels were real-time monitored in L6 cells using a laser scanning confocal microscope and related protein kinase inhibitors were used to explore the mechanism of action of ALO. Furthermore, high fat diet combined with low-dose streptozotocin (STZ) was used to induce T2DM in rats, and ALO was given to the stomach of T2DM rats for 4 weeks. In vitro results showed that ALO-induced enhancement of GLUT4 expression and translocation were mediated by G protein-PLC-PKC and PI3K/Akt pathways and ALO-enhanced intracellular Ca²⁺ was involved in activating PKC via G protein-PLC-IP₃R-Ca²⁺ pathway, resulting in promoted GLUT4 plasma membrane fusion and subsequent glucose uptake. ALO treatment effectively ameliorated hyperglycemia, glucose intolerance, insulin resistance and dyslipidemia, alleviated hepatic steatosis, protected pancreatic islet function and activated GLUT4 expression in insulin target tissues of T2DM rats. These findings demonstrated that ALO deserves attention as a potential hypoglycemic agent.

Enhancing insulin sensitivity by dual PPARγ partial agonist, β-catenin inhibitor: Design, synthesis of new αphthalimido-o-toluoyl2-aminothiazole hybrids

AIMS

Partial PPARγ agonists attracted substantially heightened interest as safer thiazolidinediones alternatives. On the other hand, Wnt/β-catenin antagonists have been highlighted as promising strategy for type 2 diabetes management via up-regulating PPARγ gene expression. We aimed at synthesizing novel partial PPARγ agonists with β-catenin inhibitory activity which could enhance insulin sensitivity and avoid the side effects of full PPARγ agonists.

MAIN METHODS

We synthesized novel series of α-phthlimido-o-toluoyl-2-aminothiazoles hybrids for evaluating their antidiabetic activity and discovering its mechanistic pathway. We assessed effect of the new hybrids on PPARγ activation using a luciferase reporter assay system. Moreover, intracellular triglyceride levels, gene levels of c/EBPα, PPARγ and PPARγ targets including GLUT4, adiponectin, aP2 were measured in 3T3-L1 cells. Uptake of 2-DOG together with PPARγ and β-catenin protein levels were evaluated in 3T3-L1cells. In addition, molecular docking studies with PPARγ LBD, physicochemical properties and structure activity relationship of the novel hybrids were also studied.

KEY FINDINGS

Three of the synthesized hybrids showed partial PPARγ agonistic activity and distinct PPARγ binding pattern. These compounds modulated PPARγ gene expression and PPARγ target genes; and increased glucose uptake in 3T3-L1 and slightly induced adipogenesis compared to rosiglitazone. Moreover, these compounds reduced β-catenin protein level which reflected in increased both PPARγ gene and protein levels that leads to improved insulin sensitivity and increased GLUT4 and adiponectin gene expression.

SIGNIFICANCE

Our synthesized compounds act as novel partial PPARγ agonists and β-catenin inhibitors that have potent insulin sensitizing activity and mitigate the lipogenic side effects of TZDs.

Effects of a Red Orange and Lemon Extract in Obese Diabetic Zucker Rats: Role of Nicotinamide Adenine Dinucleotide Phosphate Oxidase

Diabetic nephropathy (DN) is the primary cause of end-stage renal disease, worldwide, and oxidative stress has been recognized as a key factor in the pathogenesis and progression of DN. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase has the most important contribution to reactive oxygen species generation during the development of DN. Bioactive compound use has emerged as a potential approach to reduce chronic renal failure. Therefore, a red orange and lemon extract (RLE) rich in anthocyanins was chosen in our study, to reduce the toxic renal effects during the development of DN in Zucker diabetic fatty rat (ZDF). RLE effects were examined daily for 24 weeks, through gavage, in ZDF rats treated with RLE (90 mg/kg). At the end of the experiment, ZDF rats treated with RLE showed a reduction of the diabetes-associated up-regulation of both NOX4 and the p47-phox and p22-phox subunits, and restored the BAX/BCL-2 ratio respect to ZDF rats. Furthermore, RLE was able to reduce the oxidative DNA damage measured in urine samples in ZDF rats. This study showed that RLE could prevent the renal damage induced by DN through its capacity to inhibit NOX4 and apoptosis mechanisms.

Effects of Nigella Sativa on Type-2 Diabetes Mellitus: A Systematic Review

Diabetes mellitus is one of the most prevalent metabolic disorders that affect people of all genders, ages, and races. Medicinal herbs have gained wide attention from researchers and have been considered to be a beneficial adjuvant agent to oral antidiabetic drugs because of their integrated effects. Concerning the various beneficial effects of Nigella sativa, this systematic review aims to provide comprehensive information on the effects of Nigella sativa on glucose and insulin profile status in humans. A computerized database search performed through Scopus and Medline via Ebscohost with the following set of keywords: Nigella Sativa OR black seed oil OR thymoquinone OR black cumin AND diabetes mellitus OR hyperglycemia OR blood glucose OR hemoglobin A1C had returned 875 relevant articles. A total of seven articles were retrieved for further assessment and underwent data extraction to be included in this review. Nigella sativa was shown to significantly improve laboratory parameters of hyperglycemia and diabetes control after treatment with a significant fall in fasting blood glucose, blood glucose level 2 h postprandial, glycated hemoglobin, and insulin resistance, and a rise in serum insulin. In conclusion, these findings suggested that Nigella sativa could be used as an adjuvant for oral antidiabetic drugs in diabetes control.

Nano-curcumin safely prevents streptozotocin-induced inflammation and apoptosis in pancreatic beta cells for effective management of Type 1 diabetes mellitus

BACKGROUND AND PURPOSE

Approaches to prevent selective and progressive loss of insulin-producing beta cells in Type 1 diabetes mellitus (T1DM) will help to manage this prevalent and devastating disease. Curcumin (CUR), a natural anti-inflammatory substance, suppresses diabetes-associated inflammation and cell death. However, very high doses need to be used because of poor oral bioavailability, making it difficult to translate the anti-inflammatory actions to clinical situations.

EXPERIMENTAL APPROACH

We have prepared biodegradable nanosystems encapsulating curcumin (nCUR), resulting in at least nine-fold improvement in oral bioavailability. Here, we tested the ability of nCUR to prevent streptozotocin (STZ)-induced inflammation and apoptosis in pancreatic islets and beta cells, in rats.

KEY RESULTS

Non-fasted rats pretreated with 10 or 50 mg·kg^-1 nCUR 6 h prior to STZ challenge had up to 37% reduction in the glucose levels, while plain CUR (50 mg·kg^-1 ) results in 12% reduction. This treatment with nCUR was accompanied by decreased islet or beta cell death, as shown by TUNEL assay and H&E staining. Both CUR and nCUR significantly decreased levels of inflammatory cytokines in pancreatic tissue homogenates that correlated well with minimal histiocytic infiltration. Pre-treatment with nCUR, but not CUR, decreased 8-oxo-2'-deoxyguanosine, a sensitive biomarker of ROS-induced DNA damage, in pancreas. In normal rodents, daily dosing for 28 days, with nCUR (25-100 mg·kg^-1 ) did not cause any deleterious health issues by the carrier.

CONCLUSIONS AND IMPLICATIONS

Together, these data indicate a potentially translatable dose of nCUR that is safe and efficacious in improving beta cell function, which could prevent T1DM.

Marine Organisms with Anti-Diabetes Properties

Diabetes is a chronic degenerative metabolic disease with high morbidity and mortality rates caused by its complications. In recent years, there has been a growing interest in looking for new bioactive compounds to treat this disease, including metabolites of marine origin. Several aquatic organisms have been screened to evaluate their possible anti-diabetes activities, such as bacteria, microalgae, macroalgae, seagrasses, sponges, corals, sea anemones, fish, salmon skin, a shark fusion protein as well as fish and shellfish wastes. Both in vitro and in vivo screenings have been used to test anti-hyperglycemic and anti-diabetic activities of marine organisms. This review summarizes recent discoveries in anti-diabetes properties of several marine organisms as well as marine wastes, existing patents and possible future research directions in this field.

Curcumin ameliorates autoimmune diabetes. Evidence in accelerated murine models of type 1 diabetes

Type 1 diabetes (T1DM) is a T cell-mediated autoimmune disease that selectively destroys pancreatic β cells. The only possible cure for T1DM is to control autoimmunity against β cell-specific antigens. We explored whether the natural compound curcumin, with anti-oxidant and anti-inflammatory activities, might down-regulate the T cell response that destroys pancreatic β cells to improve disease outcome in autoimmune diabetes. We employed two accelerated autoimmune diabetes models: (i) cyclophosphamide (CYP) administration to non-obese diabetic (NOD) mice and (ii) adoptive transfer of diabetogenic splenocytes into NODscid mice. Curcumin treatment led to significant delay of disease onset, and in some instances prevented autoimmune diabetes by inhibiting pancreatic leucocyte infiltration and preserving insulin-expressing cells. To investigate the mechanisms of protection we studied the effect of curcumin on key immune cell populations involved in the pathogenesis of the disease. Curcumin modulates the T lymphocyte response impairing proliferation and interferon (IFN)-γ production through modulation of T-box expressed in T cells (T-bet), a key transcription factor for proinflammatory T helper type 1 (Th1) lymphocyte differentiation, both at the transcriptional and translational levels. Also, curcumin reduces nuclear factor (NF)-κB activation in T cell receptor (TCR)-stimulated NOD lymphocytes. In addition, curcumin impairs the T cell stimulatory function of dendritic cells with reduced secretion of proinflammatory cytokines and nitric oxide (NO) and low surface expression of co-stimulatory molecules, leading to an overall diminished antigen-presenting cell activity. These in-vitro effects correlated with ex-vivo analysis of cells obtained from curcumin-treated mice during the course of autoimmune diabetes. These findings reveal an effective therapeutic effect of curcumin in autoimmune diabetes by its actions on key immune cells responsible for β cell death.

Vasculoprotective effects of combined endothelial progenitor cells and mesenchymal stem cells in diabetic wound care: their potential role in decreasing wound-oxidative stress

To investigate whether the combined endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) could enhance angiogenesis and wound healing in diabetic mice. Balb/c nude mice were divided into five groups, including a control group, diabetic group (DM), DM injected with 1 × 10⁶  cells MSCs, DM injected with 1 × 10⁶  cells EPCs, and DM injected with combined 0.5 × 10⁶  cells MSCs and 0.5 × 10⁶  cells EPCs. After seven weeks, the mice were anesthetized, and bilateral full-thickness excision skin wounds were made on the dorsorostral back. The percentage of wound closure in DM group decreased significantly than in control and all other treated groups on day 7 and day 14 (P < 0.005). On day 14, the percentage of capillary vascularity in combine-treated group was significantly higher than in DM (P < 0.005). In the present study, we have demonstrated that the combined EPCs and MSCs can increase vascular endothelial growth factor (VEGF) level and angiogenesis which resulted in reduced neutrophil infiltration, decreased malondialdehyde (MDA) levels, and enhanced wound healing in diabetic mice model.

The benefits of using genetic information to design prevention trials

Clinical trials for preventative therapies are complex and costly endeavors focused on individuals likely to develop disease in a short time frame, randomizing them to treatment groups, and following them over time. In such trials, statistical power is governed by the rate of disease events in each group and cost is determined by randomization, treatment, and follow-up. Strategies that increase the rate of disease events by enrolling individuals with high risk of disease can significantly reduce study size, duration, and cost. Comprehensive study of common, complex diseases has resulted in a growing list of robustly associated genetic markers. Here, we evaluate the utility--in terms of trial size, duration, and cost--of enriching prevention trial samples by combining clinical information with genetic risk scores to identify individuals at greater risk of disease. We also describe a framework for utilizing genetic risk scores in these trials and evaluating the associated cost and time savings. With type 1 diabetes (T1D), type 2 diabetes (T2D), myocardial infarction (MI), and advanced age-related macular degeneration (AMD) as examples, we illustrate the potential and limitations of using genetic data for prevention trial design. We illustrate settings where incorporating genetic information could reduce trial cost or duration considerably, as well as settings where potential savings are negligible. Results are strongly dependent on the genetic architecture of the disease, but we also show that these benefits should increase as the list of robustly associated markers for each disease grows and as large samples of genotyped individuals become available.

Diabetes Mellitus: New Challenges and Innovative Therapies

Diabetes is a common chronic disease affecting an estimated 285 million adults worldwide. The rising incidence of diabetes, metabolic syndrome, and subsequent vascular diseases is a major public health problem in industrialized countries. This chapter summarizes current pharmacological approaches to treat diabetes mellitus and focuses on novel therapies for diabetes mellitus that are under development.

There is great potential for developing a new generation of therapeutics that offer better control of diabetes, its co-morbidities and its complications. Preclinical results are discussed for new approaches including AMPK activation, the FGF21 target, cell therapy approaches, adiponectin mimetics and novel insulin formulations. Gene-based therapies are among the most promising emerging alternatives to conventional treatments. Therapies based on gene silencing using vector systems to deliver interference RNA to cells (i.e. against VEGF in diabetic retinopathy) are also a promising therapeutic option for the treatment of several diabetic complications.

In conclusion, treatment of diabetes faces now a new era that is characterized by a variety of innovative therapeutic approaches that will improve quality of life in the near future.

Cost-effectiveness of an exercise program during pregnancy to prevent gestational diabetes: results of an economic evaluation alongside a randomised controlled trial

Background

The prevalence of gestational diabetes mellitus (GDM) is increasing worldwide. GDM and the risks associated with GDM lead to increased health care costs and losses in productivity. The objective of this study is to evaluate whether the FitFor2 exercise program during pregnancy is cost-effective from a societal perspective as compared to standard care.

Methods

A randomised controlled trial (RCT) and simultaneous economic evaluation of the FitFor2 program were conducted. Pregnant women at risk for GDM were randomised to an exercise program to prevent high maternal blood glucose (n = 62) or to standard care (n = 59). The exercise program consisted of two sessions of aerobic and strengthening exercises per week. Clinical outcome measures were maternal fasting blood glucose levels, insulin sensitivity and infant birth weight. Quality of life was measured using the EuroQol 5-D and quality-adjusted life-years (QALYs) were calculated. Resource utilization and sick leave data were collected by questionnaires. Data were analysed according to the intention-to-treat principle. Missing data were imputed using multiple imputations. Bootstrapping techniques estimated the uncertainty surrounding the cost differences and incremental cost-effectiveness ratios.

Results

There were no statistically significant differences in any outcome measure. During pregnancy, total health care costs and costs of productivity losses were statistically non-significant (mean difference €1308; 95%CI €-229 - €3204). The cost-effectiveness analyses showed that the exercise program was not cost-effective in comparison to the control group for blood glucose levels, insulin sensitivity, infant birth weight or QALYs.

Conclusion

The twice-weekly exercise program for pregnant women at risk for GDM evaluated in the present study was not cost-effective compared to standard care. Based on these results, implementation of this exercise program for the prevention of GDM cannot be recommended.

Trial registration

NTR1139

EZSCAN™ a new technology to detect diabetes risk

Key to putting prevention of diabetes into practice is finding the people with increased risk. Several tools are currently in use: oral glucose tolerance test, fasting glucose measurement and a number of questionnaires to identify those with increased risk. Each has its own advantages and disadvantages. One new tool that can identify those with increased diabetes risk is the EZSCAN™. This new diagnostic device developed by Impeto Medical uses the sweat gland function to detect risk for insulin resistance and diabetes. The basic pathophysiology behind this technology is supported by the growing number of clinical studies worldwide which show a strong association between small nerve neuropathies to insulin resistance and diabetes risk. Because the EZSCAN™ test takes only three minutes to run, is non-invasive and easy to operate, it is an ideal diagnostic tool for both the medical and paramedical setting. Several applications are possible: the EZSCAN™ can be used to monitor insulin resistance-based treatment, to diagnose increased diabetes risk and to aid proposing diabetes prevention programmes. EZSCAN™ has the potential to become a very useful tool in diabetes risk diagnostics.

Interventions for preventing gestational diabetes mellitus: a systematic review and meta-analysis

BACKGROUND

The prevalence of gestational diabetes mellitus (GDM) is increasing worldwide. GDM is associated with increased risks for mother and child during pregnancy and in later life. The aim of this article is to systematically review literature on the effectiveness of interventions to prevent GDM.

METHODS

Controlled trials found in PubMed, EMBASE, or CENTRAL were selected. The primary outcome was GDM, and relevant secondary outcomes were maternal fasting blood glucose and large-for-gestational age (LGA) or macrosomia. Data were combined in meta-analyses, and the quality of evidence for the effectiveness of the interventions was assessed in a GRADE approach.

RESULTS

Nineteen studies evaluating six types of interventions were included. Dietary counseling significantly reduced GDM incidence compared to standard care. None of the interventions was effective in lowering maternal fasting blood glucose. Low glycemic index (LGI) diet advice and an exercise program significantly reduced the risk of macrosomia. The quality of evidence for these outcomes was low.

CONCLUSIONS

The results indicate that there may be some benefits of dietary counseling, an LGI diet advice, or an exercise program. However, better-designed studies are required to generate higher quality evidence. At the moment, no strong conclusions can be drawn with regard to the best intervention for prevention of GDM.

DiaPep277 peptide therapy in the context of other immune intervention trials in type 1 diabetes

INTRODUCTION

Type 1 diabetes (T1D) is characterized by the autoimmune destruction of pancreatic β-cells. The aim of immune intervention is to arrest this autoimmune attack. DiaPep277, a major T-cell epitope of heat shock protein 60 (hsp60), has been shown to be effective in the modulation of the immune response in recent onset T1D and is the main focus of this review in the context of other ongoing trials using different approaches.

AREAS COVERED

The authors performed a literature search of Pubmed listed publications (from the last 10 years) and a website search of the company licensing DiaPep277. DiaPep277 has been investigated in Phase I - III trials in humans. Phase II trials showed a significant preservation of β-cell function in adult T1D patients (but not children) with an absence of adverse effects and not accompanied by lower glycosylated haemoglobin (HbA1c) levels or reduced daily insulin requirement compared with placebo-treated patients.

EXPERT OPINION

Administration of DiaPep277 is safe and represents a promising therapeutic strategy in patients with recent-onset T1D. The results of two large Phase III trials will tell us whether this therapy may change our current approach to treating T1D patients at diagnosis.

Characterization of the Antidiabetic Role of Parkinsonia aculeata (Caesalpineaceae)

This paper reports the characterization of the antidiabetic role of a hydroethanolic extract from Parkinsonia aerial parts (HEPA), in normal and alloxan-induced diabetic rats, treated with HEPA (125 and 250 mg/kg; p.o.). Oral glucose tolerance test, acute oral toxicity test and preliminary phytochemical analyses were performed. The diabetic rats treated with HEPA showed a significant reduction in serum and urinary glucose, urinary urea and triglyceride levels, as compared to the diabetic untreated group. However, in the normal treated groups, a significant reduction was found only in serum triglyceride levels. In all treated diabetic groups, an improvement in hepatic glycogen was observed, as well as a decrease in liquid intake and urinary volume, and an enhancement in the weight of skeletal muscles (soleus and extensor digitorum longus), kidneys and epididymal adipose tissue. Nevertheless, body and liver weights were ameliorated only in the diabetic group treated with HEPA (250 mg/kg). Moreover, oral glucose tolerance was higher in animals treated with HEPA, while results also showed that HEPA could be considered toxicologically safe. Phytochemical analysis revealed the presence of tanins, flavonoids and steroids in HEPA. In conclusion, P. aculeata presents an antidiabetic activity and other beneficial effects that ameliorate diabetes and associated complications.

Vitamin D role and use in prediabetes

OBJECTIVE

To review the role of vitamin D in prediabetes on the basis of evidence from human studies.

METHODS

English-language literature in MEDLINE (January 1969-July 2009) was searched for observational studies and randomized controlled trials of vitamin D deficiency and treatment in prediabetes, including impaired fasting glucose, impaired glucose tolerance, and metabolic syndrome. Search terms included hyperglycemia, glucose, glycohemoglobin, insulin resistance, diabetes, homeostasis model assessment, insulin secretion, vitamin D, and related terms. Publications were also identified from review articles and references in the found articles. Abstracts, conference proceedings, case reports, and letters were excluded. Articles concerning only type 1 and type 2 diabetes, hemodialysis, or hyperparathyroidism and studies in children were also excluded.

RESULTS

Vitamin D insufficiency is defined by a circulating 25-hydroxyvitamin D concentration less than 30 ng/mL, and it is prevalent in the United States (77% of the population). Most cross-sectional and prospective studies in various populations show inverse association between circulating 25-hydroxyvitamin D and fasting plasma glucose, impaired glucose tolerance, hemoglobin A1c, metabolic syndrome, and incidence of prediabetes. A few clinical trials suggest beneficial effect of vitamin D supplementation in prediabetes, including improved insulin secretion, basal fasting insulin sensitivity, and postprandial peripheral insulin resistance. The limitations of the studies are small sample size, short duration of follow-up, lack of control groups, and inability to achieve vitamin D sufficiency with treatment.

CONCLUSION

Available data suggest that achieving vitamin D sufficiency may be beneficial in patients with prediabetes, although clinical trials are needed to provide evidence-based recommendations.

Involvement of RAGE, NADPH oxidase, and Ras/Raf-1 pathway in glycated LDL-induced expression of heat shock factor-1 and plasminogen activator inhibitor-1 in vascular endothelial cells

Atherothrombotic cardiovascular diseases are the predominant causes of mortality of diabetic patients. Plasminogen activator inhibitor-1 (PAI-1) is the major physiological inhibitor for fibrinolysis, and it is also implicated in inflammation and tissue remodeling. Increased levels of PAI-1 and glycated low-density lipoprotein (glyLDL) were detected in patients with diabetes. Previous studies in our laboratory demonstrated that heat shock factor-1 (HSF1) is involved in glyLDL-induced PAI-1 overproduction in vascular endothelial cells (EC). The present study investigated transmembrane signaling mechanisms involved in glyLDL-induced HSF1 and PAI-1 up-regulation in cultured human vascular EC and streptozotocin-induced diabetic mice. Receptor for advanced glycation end products (RAGE) antibody prevented glyLDL-induced increase in the abundance of PAI-1 in EC. GlyLDL significantly increased the translocation of V-Ha-Ras Harvey rat sarcoma viral oncogene homologue (H-Ras) from cytoplasm to membrane compared with LDL. Farnesyltransferase inhibitor-277 or small interference RNA against H-Ras inhibited glyLDL-induced increases in HSF1 and PAI-1 in EC. Treatment with diphenyleneiodonium, a nicotinamide adenine dinucleotide phosphate oxidase (NOX) inhibitor, blocked glyLDL-induced translocation of H-Ras, elevated abundances of HSF1 and PAI-1 in EC, and increased release of hydrogen peroxide from EC. Small interference RNA for p22(phox) prevented glyLDL-induced expression of NOX2, HSF1, and PAI-1 in EC. GlyLDL significantly increased V-raf-1 murine leukemia viral oncogene homolog 1 (Raf-1) phosphorylation. Treatment with Raf-1 inhibitor blocked glyLDL-induced increase of PAI-1 mRNA in EC. The levels of RAGE, H-Ras, NOX4, HSF1, and PAI-1 were increased in hearts of streptozotocin-diabetic mice and positively correlated with plasma glucose. The results suggest that RAGE, NOX, and H-Ras/Raf-1 are implicated in the up-regulation of HSF1 or PAI-1 in vascular EC under diabetes-associated metabolic stress.

Delineating biological pathways unique to embryonic stem cell-derived insulin-producing cell lines from their noninsulin-producing progenitor cell lines

To identify unique biochemical pathways in embryonic stem cell-derived insulin-producing cells as potential therapeutic targets to prevent or delay beta-cell dysfunction or death in diabetic patients, comparative genome-wide gene expression studies of recently derived mouse insulin-producing cell lines and their progenitor cell lines were performed using microarray technology. Differentially expressed genes were functionally clustered to identify important biochemical pathways in these insulin-producing cell lines. Biochemical or cellular assays were then performed to assess the relevance of these pathways to the biology of these cells. A total of 185 genes were highly expressed in the insulin-producing cell lines, and computational analysis predicted the pentose phosphate pathway (PPP), clathrin-mediated endocytosis, and the peroxisome proliferator-activated receptor (PPAR) signaling pathway as important pathways in these cell lines. Insulin-producing ERoSHK cells were more resistant to hydrogen peroxide (H(2)O(2))-induced oxidative stress. Inhibition of PPP by dehydroepiandrosterone and 6-aminonicotinamide abrogated this H(2)O(2) resistance with a concomitant decrease in PPP activity as measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Clathrin-mediated endocytosis, which is essential in maintaining membrane homeostasis in secreting cells, was up-regulated by glucose in ERoSHK but not in their progenitor ERoSH cells. Its inhibition by chlorpromazine at high glucose concentration was toxic to the cells. Troglitazone, a PPARG agonist, up-regulated expression of Ins1 and Ins2 but not Glut2. Gene expression analysis has identified the PPP, clathrin-mediated endocytosis, and the PPAR signaling pathway as the major delineating pathways in these insulin-producing cell lines, and their biological relevance was confirmed by biochemical and cellular assays.

Immune cell crosstalk in type 1 diabetes

The development of type 1 diabetes involves a complex interaction between pancreatic beta-cells and cells of both the innate and adaptive immune systems. Analyses of the interactions between natural killer (NK) cells, NKT cells, different dendritic cell populations and T cells have highlighted how these different cell populations can influence the onset of autoimmunity. There is evidence that infection can have either a potentiating or inhibitory role in the development of type 1 diabetes. Interactions between pathogens and cells of the innate immune system, and how this can influence whether T cell activation or tolerance occurs, have been under close scrutiny in recent years. This Review focuses on the nature of this crosstalk between the innate and the adaptive immune responses and how pathogens influence the process.

Agonist of growth hormone-releasing hormone as a potential effector for survival and proliferation of pancreatic islets

Therapeutic strategies for transplantation of pancreatic islet cells are urgently needed to expand beta-cell mass by stimulating islet cell proliferation and/or prolonging islet cell survival. Control of the islets by different growth factors provides a potential venue for augmenting beta-cell mass. In the present study, we show the expression of the biologically active splice variant-1 (SV-1) of growth hormone-releasing hormone (GHRH) receptor in rat insulinoma (INS-1) cells as well as in rat and human pancreatic islets. In studies in vitro of INS-1 cells, the GHRH agonist JI-36 caused a significant increase in cell proliferation and a reduction of cell apoptosis. JI-36 increased islet size and glucose-stimulated insulin secretion in isolated rat islets after 48-72 h. At the ultrastructural level, INS-1 cells treated with agonist JI-36 revealed a metabolic active stimulation state with increased cytoplasm. Coincubation with the GHRH antagonist MIA-602 reversed the actions of the agonist JI-36, indicating the specificity of this agonist. In vivo, the function of pancreatic islets was assessed by transplantation of rat islets under the kidney capsule of streptozotocin-induced diabetic non-obese diabetic-severe combined immunodeficiency (NOD-SCID) mice. Islets treated with GHRH agonist JI-36 were able to achieve normoglycemia earlier and more consistently than untreated islets. Furthermore, in contrast to diabetic animals transplanted with untreated islets, insulin response to an i.p. glucose tolerance test (IPGTT) in animals receiving islets treated with agonist Jl-36 was comparable to that of normal healthy mice. In conclusion, our study provides evidence that agonists of GHRH represent a promising pharmacological therapy aimed at promoting islet graft growth and proliferation in diabetic patients.

Diabetes mellitus: new challenges and innovative therapies

Diabetes mellitus is a widespread disease prevalence and incidence of which increases worldwide. The introduction of insulin therapy represented a major breakthrough in type 1 diabetes; however, frequent hyper- and hypoglycemia seriously affects the quality of life of these patients. New therapeutic approaches, such as whole pancreas transplant or pancreatic islet transplant, stem cell, gene therapy and islets encapsulation are discussed in this review. Regarding type 2 diabetes, therapy has been based on drugs that stimulate insulin secretion (sulphonylureas and rapid-acting secretagogues), reduce hepatic glucose production (biguanides), delay digestion and absorption of intestinal carbohydrate (alpha-glucosidase inhibitors) or improve insulin action (thiazolidinediones). This review is also focused on the newer therapeutically approaches such as incretin-based therapies, bariatric surgery, stem cells and other emerging therapies that promise to further extend the options available. Gene-based therapies are among the most promising emerging alternatives to conventional treatments. Some of these therapies rely on genetic modification of non-differentiated cells to express pancreatic endocrine developmental factors, promoting differentiation of non-endocrine cells into β-cells, enabling synthesis and secretion of insulin in a glucose-regulated manner. Alternative therapies based on gene silencing using vector systems to deliver interference RNA to cells (i.e. against VEGF in diabetic retinopathy) are also a promising therapeutic option for the treatment of several diabetic complications. In conclusion, treatment of diabetes faces now a new era that is characterized by a variety of innovative therapeutic approaches that will improve quality-life and allow personalized therapy-planning in the near future.

Combination of nateglinide with thiazolidinediones in Type 2 diabetes

Insulin sensitivity and insulin secretion are reciprocally related such that insulin resistance is adapted by increased insulin secretion to maintain normal glucose and lipid homeostasis. Treatment of Type 2 diabetes should aim to restore and sustain the normal relationship between insulin sensitivity and secretion. Nateglinide is a rapid-onset, short-acting insulin-secretion enhancer that restores early-phase insulin secretion, reduces postprandial glucose excursions and prevents long-term hyperinsulinemia. Given its mechanism of action, it is evident that nateglinide would be more effective when used in combination with an insulin sensitizer, such as the thiazolidinediones. Thiazolidinediones do not stimulate insulin release and, therefore, are potentially suitable candidates for combination therapy with an insulin-secretion enhancer, such as nateglinide. Combination therapy of thiazolidinediones with nateglinide is effective, carries low risk of hypoglycemia and is suitable for patients with moderate renal impairment, although weight gain and edema are common side effects. Further studies are needed to determine whether nateglinide in combination with thiazolidinediones will help clinicians better achieve their treatment goals in targeting Type 2 diabetes. Moreover, comparative studies between nateglinide and medications targeting postprandial glycemia, such as dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 analogues, are necessary. This article summarizes data concerning the mechanism of action, efficacy and safety of therapy with nateglinide and thiazolidinediones as monotherapy and in combination treatment, and aims at a better understanding of the substrate defects their synergy hopes to defy.