Metformin and its clinical use: new insights for an old drug in clinical practice

Effects of oral antidiabetic agents on the renin-angiotensin-aldosterone system

BACKGROUND

The renin-angiotensin-aldosterone system (RAAS) is a vital endocrine system that plays a crucial role in maintaining homeostasis. However, excessive activation of the RAAS can contribute to the pathogenesis of certain diseases. Prolonged hyperglycemia leads to overactivation of the RAAS through the production of inflammatory factors and other mechanisms, ultimately resulting in diabetic complications. Oral antidiabetic agents are the cornerstone of diabetes treatment, and the effects of oral antidiabetic agents on the RAAS have not been clearly summarized.

OBJECTIVE

To review the effects of various types of oral antidiabetic agents on the components of the RAAS.

RESULTS

Sodium-glucose cotransporter inhibitors (SGLT2i) inhibit glucose and sodium reabsorption, which increases the flow of Na+ to the macula densa, thereby inhibiting tubuloglomerular feedback (TGF) and subsequently decreasing renin production. GLP-1 receptor agonists (GLP-1RA) and dipeptidyl peptidase-4 inhibitors (DPP-4i) can directly inhibit angiotensin II (Ang II) or indirectly suppress it by modulating TGF. These agents also affect Ang II type 1 receptors (AT1R) and Ang II type 2 receptors (AT2R) to mitigate Ang II and can indirectly interact with Ang II through Na+/H+ exchanger isotope 3 (NHE3). Thiazolidinediones (TZDs), as PPAR-γ agonists, can enhance the expression of the renin gene, inhibit the production of angiotensin-converting enzyme (ACE), regulate the levels of AT1R and AT2R, and decrease aldosterone production. Metformin also inhibits the production of renin and aldosterone in patients with polycystic ovary syndrome (PCOS).

CONCLUSIONS

These oral agents, which exhibit diverse effects on the components of the RAAS, modulate the activity of these components to exert antihypertensive, anti-inflammatory, cardioprotective, and renoprotective effects, thereby offering several beneficial outcomes in the management of diabetes.

A multiplexed, single-cell sequencing screen identifies compounds that increase neurogenic reprogramming of murine Muller glia

Retinal degeneration in mammals causes permanent loss of vision, due to an inability to regenerate naturally. Some non-mammalian vertebrates show robust regeneration, via Muller glia (MG). We have recently made significant progress in stimulating adult mouse MG to regenerate functional neurons by transgenic expression of the proneural transcription factor Ascl1. While these results showed that MG can serve as an endogenous source of neuronal replacement, the efficacy of this process is limited. With the goal of improving this in mammals, we designed a small molecule screen using sci-Plex, a method to multiplex up to thousands of single-nucleus RNA-seq conditions into a single experiment. We used this technology to screen a library of 92 compounds, identified, and validated two that promote neurogenesis in vivo. Our results demonstrate that high-throughput single-cell molecular profiling can substantially improve the discovery process for molecules and pathways that can stimulate neural regeneration and further demonstrate the potential for this approach to restore vision in patients with retinal disease.

Metformin Enhances Antibody-Mediated Recognition of HIV-Infected CD4+ T-Cells by Decreasing Viral Release

The mechanistic target of rapamycin (mTOR) positively regulates multiple steps of the HIV-1 replication cycle. We previously reported that a 12-weeks supplementation of antiretroviral therapy (ART) with metformin, an indirect mTOR inhibitor used in type-2 diabetes treatment, reduced mTOR activation and HIV transcription in colon-infiltrating CD4+ T-cells, together with systemic inflammation in nondiabetic people with HIV-1 (PWH). Herein, we investigated the antiviral mechanisms of metformin. In a viral outgrowth assay performed with CD4+ T-cells from ART-treated PWH, and upon infection in vitro with replication-competent and VSV-G-pseudotyped HIV-1, metformin decreased virion release, but increased the frequency of productively infected CD4lowHIV-p24+ T-cells. These observations coincided with increased BST2/Tetherin (HIV release inhibitor) and Bcl-2 (pro-survival factor) expression, and improved recognition of productively infected T-cells by HIV-1 Envelope antibodies. Thus, metformin exerts pleiotropic effects on post-transcription/translation steps of the HIV-1 replication cycle and may be used to accelerate viral reservoir decay in ART-treated PWH.

Metformin Resistance Is Associated with Expression of Inflammatory and Invasive Genes in A549 Lung Cancer Cells

Metformin, the most commonly used drug for type 2 diabetes, has recently been shown to have beneficial effects in patients with cancer. Despite growing evidence that metformin can inhibit tumor cell proliferation, invasion, and metastasis, studies on drug resistance and its side effects are lacking. Here, we aimed to establish metformin-resistant A549 human lung cancer cells (A549-R) to determine the side effects of metformin resistance. Toward this, we established A549-R by way of prolonged treatment with metformin and examined the changes in gene expression, cell migration, cell cycle, and mitochondrial fragmentation. Metformin resistance is associated with increased G1-phase cell cycle arrest and impaired mitochondrial fragmentation in A549 cells. We demonstrated that metformin resistance highly increased the expression of proinflammatory and invasive genes, including BMP5, CXCL3, VCAM1, and POSTN, using RNA-seq analysis. A549-R exhibited increased cell migration and focal adhesion formation, suggesting that metformin resistance may potentially lead to metastasis during anti-cancer therapy with metformin. Taken together, our findings indicate that metformin resistance may lead to invasion in lung cancer cells.

Pleiotropic Effects of Metformin in Osteoarthritis

The involvement of the knee joint is the most common localization of the pathological process in osteoarthritis (OA), which is associated with obesity in over 50% of the patients and is mediated by mechanical, inflammatory, and metabolic mechanisms. Obesity and the associated conditions (hyperglycemia, dyslipidemia, and hypertension) have been found to be risk factors for the development of knee OA, which has led to the emerging concept of the existence of a distinct phenotype, i.e., metabolic knee OA. Combined assessment of markers derived from dysfunctional adipose tissue, markers of bone and cartilage metabolism, as well as high-sensitivity inflammatory markers and imaging, might reveal prognostic signs for metabolic knee OA. Interestingly, it has been suggested that drugs used for the treatment of other components of the metabolic syndrome may also affect the clinical course and retard the progression of metabolic-associated knee OA. In this regard, significant amounts of new data are accumulating about the role of metformin-a drug, commonly used in clinical practice with suggested multiple pleiotropic effects. The aim of the current review is to analyze the current views about the potential pleiotropic effects of metformin in OA. Upon the analysis of the different effects of metformin, major mechanisms that might be involved in OA are the influence of inflammation, oxidative stress, autophagy, adipokine levels, and microbiome modulation. There is an increasing amount of evidence from in vitro studies, animal models, and clinical trials that metformin can slow OA progression by modulating inflammatory and metabolic factors that are summarized in the current up-to-date review. Considering the contemporary concept about the existence of metabolic type knee OA, in which the accompanying obesity and systemic low-grade inflammation are suggested to influence disease course, metformin could be considered as a useful and safe component of the personalized therapeutic approach in knee OA patients with accompanying type II diabetes or obesity.

Evaluation of Metformin Hydrochloride Tailoring Bilosomes as an Effective Transdermal Nanocarrier

Introduction

Metformin hydrochloride (metformin HCL), a first-line drug treating diabetes type II, was known to cause severe gastritis, so seeking a non-oral dosage form was the new trend. Bilosomes are bilayer nano-vesicles of non-ionic surfactants embodying bile salts. In our study, bilosomes were investigated as an acceptable novel carrier for active targeting transdermal delivery of metformin HCL, circumventing its side effects.

Methods

Twelve bilosome formulations were prepared with solvent evaporation method with slight modification according to a 3¹.2² full factorial design, and the optimized formulation was determined using Design -Expert 13 software (Stat-Ease, Inc., Minneapolis, Minnesota, USA) studying the effect of surfactant and bile salt types on the entrapment efficiency (EE), vesicle size (VS), polydispersity index (PDI), zeta potential (ZP), percentage of drug released within 24 h (R), and flux of drug permeated within 6 h (Jss) of vesicles. In addition, the optimized formulation was further evaluated to Fourier-transform infrared spectroscopy (FTIR), deformability index (DI), and transmission electron microscope (TEM) to ensure bilosomes formation, elasticity, and spherical shape, respectively.

Results

The resulting vesicles publicized EE from 56.21% to 94.21%, VS from 183.64 to 701.8 nm, PDI values oscillating between 0.33 and 0.53, ZP (absolute value) from 29 to 44.2 mV, biphasic release profile within 24 h from 60.62 and up to 75.28%, and permeation flux enhancement (198.79–431.91 ng cm ⁻² h⁻¹) in comparison with the non-formulated drug (154.26 ng cm ⁻² h⁻¹). Optimized formulation was found to be F8 with EE = 79.49%, VS = 237.68 nm, ZP = 40.9 mV, PDI = 0.325, R = 75.28%, Jss = 333.45 ng cm⁻² h⁻¹ and DI = 6.5 with spherical self-closed non-aggregated vesicles and non-superimposed bands of its components in the FTIR.

Conclusion

Overall results showed that bilosome incorporation of metformin HCL improved permeation and offered a new nano-carrier for active transdermal delivery.

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Therapeutic potentials of agonist and antagonist of adenosine receptors in type 2 diabetes

Type 2 diabetes has been a global health challenge over the decades and is among the leading causes of death. Several treatment approaches have been developed, but more effective and new therapies are still needed. The role of adenosine in glucose and lipid homeostasis has offered a different therapeutic approach. Adenosine mediates its physiological role through the activation of adenosine receptors. These adenosine receptors have been implicated in glucose and lipid homeostasis. The ability of agonists and antagonists of adenosine receptors to activate or inhibit the adenosine signalling cascade and thereby affecting the balance of glucose and lipid homeostasis has challenged the studies of agonists and antagonists of adenosine receptors, both preclinical and clinical, as potential anti-diabetic drugs. This review provides a background on different anti-diabetic therapeutic approaches, outlining the role of adenosine receptors in glucose and lipid homeostasis, and mechanisms underlying the action of agonists/antagonists of adenosine receptors as a therapeutic potential towards type 2 diabetes.

Neonatal metformin short exposure inhibits male reproductive dysfunction caused by a high-fat diet in adult rats

Metformin (Met) is widely used to control blood glucose levels and acts on various organs, including reproductive tissues, to improve reproductive and lifespan. This study evaluated whether neonatal Met exposure prevented male reproductive dysfunction caused by being overweight during adulthood. Randomized Wistar rat pups received an intraperitoneal injection from postnatal days (PNDs) 1 to 12of saline (Sal; 0.9% NaCl/day in 2mL/kg) or Met (100 mg/kg/day in 2 mL/kg). From PNDs 60 to 90, the animals received a regular (R; 4.5% fat; Sal R and Met R groups) or a high-fat (HF; 35% fat; Sal HF and Met HF groups) diet. At PND 90, all animals were euthanized to evaluate their biometric and reproductive parameters. The Sal and Met groups with R showed similar body weights, however, the HF diet increased the body weight in both groups. The Sal HF group showed testicular damage regarding in antioxidant status and inflammatory profile in the epididymal cauda. The HF diet reduced Leydig and Sertoli cells numbers, with lower sperm quality. The Met R animals showed positive reproductive programming, due to improved antioxidant defense, inflammatory biomarkers, and sperm morphology. Met HF prevented HF diet damage to reproductive organs and sperm morphology, but not to sperm motility. Early Met exposure positively affected the male reproductive system of adult rats, preventing reproductive HF disorders. STATEMENT OF NOVELTY AND SIGNIFICANCE: Metformin is used to control type 2 diabetes mellitus and can act to improve metabolism and lifespan. Metformin avoidance is recommended during pregnancy, but there is no information regarding its use when breastfeeding. For the first time, we showed in this current study that metformin positively acts in the male reproductive tissues and helps involved in later life. These data showed a better antioxidant defense and anti-inflammatory profile of Metformin animals than Saline animals and might directly improve reproductive organs morphophysiology and sperm morphology. Also, the neonatal Met application programs the male reproduction to counterbalance damages from an obesogenic environment in later life.

Cellular protein markers, therapeutics, and drug delivery strategies in the treatment of diabetes-associated liver fibrosis

Liver fibrosis is the excessive accumulation of extracellular matrix due to chronic injuries, such as viral infection, alcohol abuse, high-fat diet, and toxins. Liver fibrosis is reversible before it progresses to cirrhosis and hepatocellular carcinoma. Type 2 diabetes significantly increases the risk of developing various complications including liver diseases. Abundant evidence suggests that type 2 diabetes and liver diseases are bidirectionally associated. Patients with type 2 diabetes experience more severe symptoms and accelerated progression of live diseases. Obesity and insulin resistance resulting from hyperlipidemia and hyperglycemia are regarded as the two major risk factors that link type 2 diabetes and liver fibrosis. This review summarizes possible mechanisms of the association between type 2 diabetes and liver fibrosis. The cellular protein markers that can be used for diagnosis and therapy of type 2 diabetes-associated liver fibrosis are discussed. We also highlight the potential therapeutic agents and their delivery systems that have been investigated for type 2 diabetes-associated liver fibrosis.

Metformin and insulin-resistant related diseases: Emphasis on the role of microRNAs

Metformin is one of the most prescribed drugs in type II diabetes (T2DM) which has recently found new applications in the prevention and treatment of various illnesses, from metabolic disorders to cardiovascular and age-related diseases. Metformin improves insulin resistance (IR) by modulating metabolic mechanisms and mitochondrial biogenesis. Alternation of microRNAs (miRs) in the treatment of IR-related illnesses has been observed by metformin therapy. MiRs are small non-coding RNAs that play important roles in RNA silencing, targeting the 3'untranslated region (3'UTR) of most mRNAs and inhibiting the translation of related proteins. As a result, their dysregulation is associated with many diseases. Metformin may alter miRs levels in the treatment of various diseases by AMPK-dependent or AMPK-independent mechanisms. Here, we summarized the therapeutic role of metformin by modifying the aberrant expression of miRs as potential biomarkers or therapeutic targets in diseases in which IR plays a key role.

Hyaluronic Acid Conjugated Metformin-Phospholipid Sonocomplex: A Biphasic Complexation Approach to Correct Hypoxic Tumour Microenvironment

Purpose

Development of hyaluronic acid conjugated metformin-phospholipid sonocomplexes (HA-MPS), a biphasic complexation product compiled for enhancing both the lipophilicity and targeting potential of Metformin (MET) to CD44 receptors on pancreatic cancer.

Methods

MET was chemically conjugated to hyaluronic acid (HA) via amide coupling reaction. Then, the HA conjugated MET was physically conjugated to Lipoid™S100 via ultrasound irradiation. A combined D-optimal design was implemented to statistically optimize formulation variables. The HA-MPS were characterized through solubility studies, partition coefficient, drug content uniformity, particle size and zeta potential. The optimized HA-MPS was tested via proton nuclear magnetic resonance, infrared spectroscopy to elucidate the nature of physicochemical interactions in the complex which was further scrutinized on molecular level via molecular docking and dynamic simulation.

Results

The solubility and partition studies showed a lipophilicity enhancement up to 67 folds as they adopted inverted micelles configuration based on the packing parameter hypothesis. The optimized HA-MPS showed 11.5 folds lower IC₅₀, extra 25% reduction in oxygen consumption rate, better reduction in hypoxia-inducible factor and reactive oxygen species in MiaPaCa-2 cells.

Conclusion

These results proved better internalization of MET which was reflected by abolishing hypoxic tumour microenvironment, a mainstay toward a normoxic and less resistant pancreatic cancer.

Fanconi anemia and the underlying causes of genomic instability

Fanconi anemia (FA) is a rare genetic disorder, characterized by birth defects, progressive bone marrow failure, and a predisposition to cancer. This devastating disease is caused by germline mutations in any one of the 22 known FA genes, where the gene products are primarily responsible for the resolution of DNA interstrand cross-links (ICLs), a type of DNA damage generally formed by cytotoxic chemotherapeutic agents. However, the identity of endogenous mutagens that generate DNA ICLs remains largely elusive. In addition, whether DNA ICLs are indeed the primary cause behind FA phenotypes is still a matter of debate. Recent genetic studies suggest that naturally occurring reactive aldehydes are a primary source of DNA damage in hematopoietic stem cells, implicating that they could play a role in genome instability and FA. Emerging lines of evidence indicate that the FA pathway constitutes a general surveillance mechanism for the genome by protecting against a variety of DNA replication stresses. Therefore, understanding the DNA repair signaling that is regulated by the FA pathway, and the types of DNA lesions underlying the FA pathophysiology is crucial for the treatment of FA and FA-associated cancers. Here, we review recent advances in our understanding of the relationship between reactive aldehydes, bone marrow dysfunction, and FA biology in the context of signaling pathways triggered during FA-mediated DNA repair and maintenance of the genomic integrity. Environ. Mol. Mutagen. 2020. © 2020 Wiley Periodicals, Inc.

Histomorphological, VEGF and TGF-β immunoexpression changes in the diabetic rats' ovary and the potential amelioration following treatment with metformin and insulin

Diabetes mellitus (DM) affects the ovary by reducing the number and diameters of ovarian follicles and increasing atretic follicles. Follicular growth and diameters depend on VEGF production. Hyperglycemia causes ovarian stromal and follicular degeneration then fibrosis by activating TGF-β. Insulin and metformin promote development of ovarian follicles and reduce atretic follicles. Therefore, the present study investigates the ovarian VEGF and TGF-β immune-expression and its variations in diabetic, insulin and metformin-treated rats. Forty adult female albino rats were divided equally into four groups: control, diabetic (STZ-induced diabetes), diabetic metformin-treated group (100 mg/kg/day orally/eight weeks) and diabetic insulin-treated group (5 U insulin /day). Ovarian sections were stained with hematoxylin and eosin, Masson's trichrome, immunohistochemistry for VEGF and TGF-β. The diabetic group showed noticeable atrophic and degenerative changes in cortex and medulla as well as increased density and distribution of the collagenous fibers. The number and diameter of primary, secondary and tertiary follicles were decreased. However, the number of atretic follicles and corpus luteum was increased. Significant decrease in the surface area percentage of VEGF immuno-expression and significant increase in TGF-β immuno-expression surface area percentage were detected. By treating animals with metformin and insulin, there was restoration of the ovarian histological structure more or less as in control. DM negatively affects the histological and morphometric parameters of ovaries. Furthermore, insulin showed more beneficial effects than metformin in hindering these complications by modifying the expression of VEGF and TGF-β.

Metformin pretreatment suppresses alterations to the articular cartilage ultrastructure and knee joint tissue damage secondary to type 2 diabetes mellitus in rats

Osteoarthritis (OA) secondary to diabetes affects millions of people worldwide and can lead to disability. The protective effect of metformin pretreatment against alterations to the articular cartilage ultrastructure induced by type 2 diabetes mellitus (T2DM) associated with the inhibition of oxidative stress and inflammation has not been investigated before. Therefore, we induced T2DM in rats (the model group) using high carbohydrate and fat diet and a single injection of streptozotocin (50 mg/kg body weight). The protective group of rats started metformin (200 mg/kg body weight) treatment 14 days before diabetic induction and continued on metformin until the end of the experiment at week 12. Harvested tissues obtained from knee joints were prepared for staining with hematoxylin and eosin (H&E), safranin o staining, and electron microscopy. Histology images showed that OA was developed in the T2DM rats as demonstrated by a substantial damage to the articular cartilage and profound chondrocyte and territorial matrix ultrastructural alterations, which were partially protected by metformin. In addition, metformin significantly (p < .05) reduced hyperglycemia, glycated hemoglobin (HbA1 c), malondialdehyde (MDA), high sensitivity C-reactive protein (hs-CRP), and interleukin-6 blood levels induced by diabetes. Furthermore, a significant (p ≤ 0.015) correlation between either OA cartilage grade score or the thickness of the articular cartilage and the blood levels of HbA1 c, hs-CRP, MDA, superoxide dismutase (SOD) were observed. These findings demonstrate effective protection of the articular cartilage by metformin against damage induced secondary to T2DM in rats, possibly due to the inhibition of hyperglycemia and biomarkers of oxidative stress and inflammation.

Novel Metformin-Based Schiff Bases: Synthesis, Characterization, and Antibacterial Evaluation

Novel Schiff bases of metformin hydrochloride and (ortho)para-nitrobenzaldehyde were synthesized by employing two efficient environmentally friendly methods, namely, stirring and microwave-assisted methods using water as the solvent. The advantage of microwave irradiation over the other methods was represented in the reduction of reaction time and wastes, and good yields; however, water in both methods plays the role of eco-friendly solvent. The structural properties of the (ortho)para-isomer products were analyzed by elemental analysis, Fourier transform infrared (FTIR) spectroscopy, UV-Visible (UV-Vis) spectroscopy, ¹H nuclear magnetic resonance (NMR) spectroscopy, ¹³C NMR spectroscopy, mass spectroscopy, and differential scanning calorimetry (DSC). The newly synthesized compounds were screened for their antibacterial activity against selected Gram-positive (ATCC 25923, ATCC 43300, and ATCC 29212) and Gram-negative (ATCC 25922, ATCC 27853, and ATCC 700603) bacteria using the agar well diffusion method. Compared with the standard drug streptomycin, both Schiff bases exhibited moderate bactericidal activity against the tested bacteria with higher values of ortho-nitro compared with the para-nitro isomer; however, no effect on ATCC 43300 and ATCC 27853 was observed under the experimental conditions employed.

Relationship between metformin and abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a life-threatening disease and pharmacologic agents to treat the disease remain lacking for clinical practice. Epidemiologic studies have highlighted a negative association between the use of antidiabetic drugs, including metformin, and AAA. Metformin is well-known for its blood glucose-lowering effect, but its action on both metabolism and inflammatory response has led to propose it as a potential therapeutic target in several cardiovascular diseases. In this review, we summarize the current knowledge on the link between metformin and AAA. Based on the known effects of the drug on the aortic wall, translational applications and clinical trials investigating the interest of metformin in the management of patients with AAA are discussed.

Exploiting Mitochondrial Vulnerabilities to Trigger Apoptosis Selectively in Cancer Cells

The transformation of normal cells to the cancerous stage involves multiple genetic changes or mutations leading to hyperproliferation, resistance to apoptosis, and evasion of the host immune system. However, to accomplish hyperproliferation, cancer cells undergo profound metabolic reprogramming including oxidative glycolysis and acidification of the cytoplasm, leading to hyperpolarization of the mitochondrial membrane. The majority of drug development research in the past has focused on targeting DNA replication, repair, and tubulin polymerization to induce apoptosis in cancer cells. Unfortunately, these are not cancer-selective targets. Recently, researchers have started focusing on metabolic, mitochondrial, and oxidative stress vulnerabilities of cancer cells that can be exploited as selective targets for inducing cancer cell death. Indeed, the hyperpolarization of mitochondrial membranes in cancer cells can lead to selective importing of mitocans that can induce apoptotic effects. Herein, we will discuss recent mitochondrial-selective anticancer compounds (mitocans) that have shown selective toxicity against cancer cells. Increased oxidative stress has also been shown to be very effective in selectively inducing cell death in cancer cells. This oxidative stress could lead to mitochondrial dysfunction, which in turn will produce more reactive oxygen species (ROS). This creates a vicious cycle of mitochondrial dysfunction and ROS production, irreversibly leading to cell suicide. We will also explore the possibility of combining these compounds to sensitize cancer cells to the conventional anticancer agents. Mitocans in combination with selective oxidative-stress producing agents could be very effective anticancer treatments with minimal effect on healthy cells.

Metformin inhibits mTOR-HIF-1α axis and profibrogenic and inflammatory biomarkers in thioacetamide-induced hepatic tissue alterations

The potential inhibitory effect of the antidiabetic and anti-inflammatory drug, metformin on thioacetamide (TAA)-induced hepatotoxicity associated with the inhibition of mammalian target of rapamycin (mTOR)-hypoxia-inducible factor-1α (HIF-1α) axis has not been investigated before. Therefore, we tested whether metformin can protect against liver injuries including fibrosis induced by TAA possibly via the downregulation of mTOR-HIF-1α axis and profibrogenic and inflammatory biomarkers. Rats either injected with TAA (200 mg/kg; twice a week for 8 weeks) before being killed after 10 weeks (model group) or were pretreated with metformin (200 mg/kg) daily for 2 weeks before TAA injections and continued receiving both agents until the end of the experiment, at Week 10 (protective group). Using light and electron microscopy examinations, we observed in the model group substantial damage to the hepatocytes and liver tissue such as collagen deposition, infiltration of inflammatory cells, and degenerative cellular changes with ballooned mitochondria that were substantially ameliorated by metformin. Metformin also significantly ( p < 0.05) inhibited TAA-induced HIF-1α, mTOR, the profibrogenic biomarker α-smooth muscle actin, tissue inhibitor of metalloproteinases-1, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), alanine aminotransferase (ALT) and aspartate aminotransferase in harvested liver homogenates and blood samples. In addition, a significant ( p < 0.01) positive correlation between hypoxia scoring (HIF-1α) and the serum levels of TNF-α ( r = 0.797), IL-6 ( r = 0.859), and ALT ( r = 0.760) was observed. We conclude that metformin protects against TAA-induced hepatic injuries in rats, which is associated with the inhibition of mTOR-HIF-1α axis and profibrogenic and inflammatory biomarkers; thus, may offer therapeutic potential in humans.

Feasibility and Acceptability of Metformin to Augment Low Milk Supply: A Pilot Randomized Controlled Trial

BACKGROUND

Metformin improves insulin action, but feasibility in treating low milk supply is unknown.

RESEARCH AIM

To determine the feasibility of a metformin- versus-placebo definitive randomized clinical trial in women with low milk production and signs of insulin resistance.

METHODS

Pilot trial criteria included: Mother 1-8 weeks postpartum (ideally 1-2 weeks), low milk production, and ≥1 insulin resistance sign; and singleton, healthy, term infant. Eligible mothers were randomly assigned 2:1 (metformin:placebo) and instructed in frequent milk removal for 28 days with option to stop at 14 days.

RESULTS

From 02/2015 through 06/2016, we screened 114 women, completed baseline assessments on 46, and trialed 15 (median, 36 days postpartum). Comparing metformin-assigned ( n = 10) to placebo ( n = 5), 70% versus 80% continued to day 28; peak median change in milk output was +8 versus -58 mL/24 hr ( p = .31) and 80% peaked at Day 14 for both groups; 0% versus 20% desired to continue assigned drug after study completion; 44% versus 0% reported nausea/vomiting. Post-hoc, median peak change in milk output was +22 (metformin completers, n = 8) versus -58 mL/24 hr (placebo + non-completers, n = 7, p = .07). At baseline assessment, median milk production was significantly lower in those with ( n = 31), versus those without ( n = 15) signs of insulin resistance ( p = .002).

CONCLUSIONS

Although results trend toward hypothesized direction, trial feasibility concerns include late enrollment and only 20% of metformin-assigned participants sustaining improved milk output to Day 28, with none perceiving metformin worthwhile. Better tools are needed to identify and treat metabolically-driven low milk production. Registered at ClinicalTrials.gov (NCT02179788) on 02/JUL/2014.

Low-dose 2-deoxyglucose and metformin synergically inhibit proliferation of human polycystic kidney cells by modulating glucose metabolism

Polycystic kidney disease (PKD) is a common hereditary kidney disease with abnormal proliferation and apoptosis of kidney cystic epithelial cells, eventually leading to chronic renal failure. Currently, there are no effective treatment methods. Similar to tumor cells, cystic epithelial cells have abnormal glycolysis and over-activation of proliferation signaling pathways. In the present study, for the first time, we investigated the effects of low-dose combinational use of 2-deoxyglucose (2-DG) and metformin (MET) on the proliferation and apoptosis in the human cystic kidney epithelial cells. Cystic epithelia cells were divided into control group, 2-DG group, MET group and 2-DG+MET group. Cell Proliferation, apoptosis and glucose metabolism were measured in each group. The results showed that low-dose combinational treatment of 2-DG and MET significantly inhibited the proliferation of renal cystic epithelial cells by suppressing the activities of PKA, mTOR and ERK signaling pathways and upregulating PI3K/Akt pathway. Combination of both drugs increased the apoptosis rates of cystic epithelial cells. Two drugs inhibited glucose metabolic phenotypes, glycolysis and oxidative phosphorylation, and significantly lowered the intracellular ATP level in cystic epithelial cells. 2-DG could also neutralize excessive production of lactate (lactic acidosis) caused by MET and both drugs had complementary effect for cystic epithelial cells. These results reveal that combinational use of low-dose 2-DG and MET can markedly inhibit proliferation via modulating glucose metabolic phenotypes in human polycystic kidney epithelial cells, low-dose combinational use of both drugs can also lower the toxic effects of each drug, and is a novel strategy for future treatment of human polycystic kidney disease.

Effect of rosiglitazone on inflammatory cytokines and oxidative stress after intensive insulin therapy in patients with newly diagnosed type 2 diabetes

OBJECTIVE

To evaluate the effect of insulin sensitizer on inflammatory cytokines and oxidative stress in patients with newly diagnosed type 2 diabetes mellitus (T2DM).

METHODS

After intensive insulin therapy, patients with newly diagnosed T2DM were continuously treated with either insulin sensitizer or insulin for 48 weeks, and then their inflammatory cytokine and oxidative stress levels were measured.

RESULTS

Tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, hypersensitive C reactive protein (hs-CRP), malondialdehyde (MDA), and 8-iso-prostaglandin F2α (8-iso-PGF_2α) levels of the rosiglitazone (RSG) group and the rosiglitazone combined with metformin (RSG + metformin) group were significantly reduced after the treatments (P < 0.05). Hs-CRP, MDA, and 8-iso-PGF_2α levels of the metformin group were significantly reduced after the treatments (P < 0.05). Superoxide dismutase (SOD) and total antioxidant capacity (TAC) were significantly increased after the treatments in all three groups (P < 0.05 and P < 0.01).

CONCLUSION

Early application of insulin sensitizers improved inflammation and oxidative stress in patients with newly diagnosed T2DM.

The effects of metformin on simple obesity: a meta-analysis

OBJECTIVE

To evaluate the efficacy of metformin versus a placebo in the treatment of patients with simple obesity without obesity related diseases.

METHODS

A search was done on Pub-Med, EMBASE, Cochrane, and Science Citation Index Expanded databases. The main inclusion criteria included the following:(1) randomized controlled trials. (2) patients diagnosed as being overweight or obese. (3) patients were randomly assigned to receive metformin or control. Exclusion criteria included the following: patients diagnosed with an obesity related disease, such as diabetes mellitus (DM) or polycystic ovary syndrome (PCOS).

RESULTS

Compared with the placebo, weighted mean difference (WMD) was 2.33 (95% CI 0.31, 4.35) kg higher with metformin (p = 0.02). Compared with the placebo, WMD was 0.57 (95% CI 0.35, 0.79) kg/m² higher with metformin(p < 0.00001). There was no significant difference in the reduction of waist circumference between the metformin group and the control group (p = 0.05). The fasting blood glucose levels were significantly lower in the metformin group than in the control group (p < 0.00001). However, no hypoglycemia was noted in the metformin group or the control group.

CONCLUSION

Metformin is effective in reducing body weight of simple obesity patients, and metformin does not induce hypoglycemia as a side effect.

Metformin in cancer

Metformin is a lipophilic biguanide which inhibits hepatic gluconeogenesis and improves peripheral utilization of glucose. It is the first line pharmacotherapy for glucose control in patients with Type 2 diabetes due to its safety, efficacy and tolerability. Metformin exhibits pleotropic effects, which may have beneficial effects on a variety of tissues independent of glucose control. A potential anti-tumourigenic effect of metformin may be mediated by its role in activating AMP-kinase, which in turn inhibits mammalian target of rapamycin (mTOR). Non-AMPK dependent protective pathways may include reduction of insulin, insulin-like growth factor-1, leptin, inflammatory pathways and potentiation of adiponectin, all of which may have a role in tumourigenesis. A role in inhibiting cancer stem cells is also postulated. A number of large scale observational and cohort studies suggest metformin is associated with a reduced risk of a number of cancers, although the data is not conclusive. Recent randomised studies reporting use of metformin in treatment of cancer have revealed mixed results, and the results of much larger randomised trials of metformin as an adjuvant therapy in breast and colorectal cancers are awaited.

Modifying exosome release in cancer therapy: How can it help?

The reciprocal interactions of cancer cells with their microenvironment constitute an inevitable aspect of tumor development, progression and response to treatment in all cancers. Such bilateral transactions also serve as the key scenario underlying the development of drug resistance in many cases finally determining the fate of the disease and survival. In this view, a class of extracellular vesicles (EV) known as exosomes (EX) have been shown in the past few years to be important mediators of local and remote cell-to-cell contact changing the activity of their target cells by introducing their content of proteins, non-coding RNAs, and membrane-associated small molecules. In addition to the direct targeting of cancer cells, which has been routinely undertaken by different means to date, parallel attempts to change the signaling network governed by tumor-derived exosomes (TDE) may offer a promising potential to be utilized in cancer therapy. TDE drive diverse functions in the body, most of which have been shown to act to the advantage of tumor progression; however, there are also several studies that report the good aspects of TDE the interruption of which may result in undesirable outcomes. In the present paper, we made an effort to address this important issue by reviewing the very recent literature on different aspects of EX biogenesis and regulation and the various bodily effects of TDE which have been uncovered to date. Moreover, we have reviewed the possible interventions that can be made in TDE release as an important stage of EX biogenesis. Finally, keeping a criticizing view, the advantages and disadvantages of such interventions have been discussed and the future prospect in the field has been outlined.

Phenformin-Induced Mitochondrial Dysfunction Sensitizes Hepatocellular Carcinoma for Dual Inhibition of mTOR

Purpose: Hepatocellular carcinoma (HCC) ranks second in cancer mortality and has limited therapeutic options. We recently described the synergistic effect of allosteric and ATP-site competitive inhibitors against the mTOR for the treatment of HCC. However, such inhibitors induce hyperglycemia and increase mitochondrial efficiency. Here we determined whether the mitochondrial complex I inhibitor phenformin could reverse both side effects, impose an energetic stress on cancer cells, and suppress the growth of HCC.Experimental Design: Human HCC cell lines were used in vitro to access the signaling and energetic impact of mTOR inhibitors and phenformin, either alone or in combination. Next, the therapeutic utility of these drugs alone or in combination was investigated preclinically in human orthotopic tumors implanted in mice, by analyzing their impact on the tumor burden and overall survival.Results: We found phenformin caused mitochondrial dysfunction and fragmentation, inducing a compensatory shift to glycolysis. In contrast, dual inhibition of mTOR impaired cell growth and glycolysis, while increasing mitochondrial fusion and efficiency. In a mouse model of human HCC, dual inhibition of mTOR, together with phenformin, was highly efficacious in controlling tumor burden. However, more strikingly, pretreatment with phenformin sensitized tumors to dual inhibition of mTOR, leading to a dramatic improvement in survival.Conclusions: Treatment of HCC cells in vitro with the biguanide phenformin causes a metabolic shift to glycolysis, mitochondrial dysfunction and fragmentation, and dramatically sensitizes orthotopic liver tumors to dual inhibition of mTOR. We therefore propose this therapeutic approach should be tested clinically in HCC. Clin Cancer Res; 24(15); 3767-80. ©2018 AACR.

Validity of diagnostic codes to identify hospitalizations for infections among patients treated with oral anti-diabetic drugs

PURPOSE

Identification of hospitalizations for infection is important for post-marketing surveillance of drugs, but the validity of using diagnosis codes to identify these events is unknown. Differentiating between hospitalization for and with infection is important, as the latter is common and less likely to arise from pre-admission exposure to drugs. We determined positive predictive values (PPVs) of diagnostic coding-based algorithms to identify hospitalization for infection among patients prescribed oral anti-diabetic drugs (OADs).

METHODS

We identified patients initiating OADs within 2 United States claims databases (Medicare, HealthCore Integrated Research Database^SM [HIRD^SM ]) and 2 United Kingdom electronic medical record databases (Clinical Practice Research Datalink [CPRD], The Health Improvement Network [THIN]) from 2009 to 2014. To identify potential hospitalizations for infection, we selected patients with a hospital diagnosis of infection and, within 7 days prior to hospitalization, either an outpatient/emergency department visit with an infection diagnosis or outpatient antimicrobial treatment. Hospital records were reviewed by infectious disease specialists to adjudicate hospital admissions for infection. PPVs for confirmed outcomes were determined for each database.

RESULTS

Code-based algorithms to identify hospitalization for infection had PPVs exceeding 80% within Medicare (PPV, 83% [90/109]; 95% CI, 74-89%), HIRD^SM (PPV, 89% [73/82]; 95% CI, 80-95%), and THIN (PPV, 86% [12/14]; 95% CI, 57-98%) but not within CPRD (PPV, 67% [14/21]; 95% CI, 43-85%).

CONCLUSIONS

Algorithms identifying hospitalization for infection utilizing hospital diagnoses along with antecedent outpatient/emergency infection diagnoses or antimicrobial therapy had sufficiently high PPVs for confirmed events within Medicare, HIRD^SM , and THIN to enable their use for pharmacoepidemiologic research.

Does metformin exposure before ICU stay have any impact on patients' outcome? A retrospective cohort study of diabetic patients

BACKGROUND

Impact of metformin exposure before ICU stay remains controversial. Metformin is thought to induce lactic acidosis and haemodynamic instability but may reduce ICU mortality. We evaluated its influence on outcome in diabetic patients admitted in the ICU and then compared two different populations based on the presence of septic shock.

METHODS

We conducted a retrospective cohort study in a 24-bed French ICU between October 2010 and December 2013, including all ICU-admitted diabetic patients.

RESULTS

Among 635 diabetic patients admitted during the study period, 131 (21%) were admitted with septic shock. Multivariate analysis showed no difference in hospital mortality in all metformin users (OR 0.75 [95% CI 0.44-1.28]; p = 0.29), except in the septic shock subgroup (OR 0.61; 95% CI [0.37-0.99]; p = 0.04) despite higher vasopressor dosages in the first hours after shock onset. Blood lactate level was higher in metformin users than in non-metformin users in all patients (p < 0.001), in septic shock patients (p < 0.001) and in patients without kidney injury (p < 0.001). Metformin users did not have more septic shock from unknown aetiology (p = 0.65) or unknown pathogen (p = 0.99).

CONCLUSIONS

Metformin use before admission to ICU did not affect in-hospital mortality. However, for patients with septic shock, mortality was lower, despite worse clinical presentation on admission. Blood lactate levels were always higher with or without septic shock and indifferent of kidney function.

A Structural Basis for Biguanide Activity

Metformin is the most commonly prescribed treatment for type II diabetes and related disorders; however, molecular insights into its mode(s) of action have been limited by an absence of structural data. Structural considerations along with a growing body of literature demonstrating its effects on one-carbon metabolism suggest the possibility of folate mimicry and anti-folate activity. Motivated by the growing recognition that anti-diabetic biguanides may act directly upon the gut microbiome, we have determined structures of the complexes formed between the anti-diabetic biguanides (phenformin, buformin, and metformin) and Escherichia coli dihydrofolate reductase (ecDHFR) based on nuclear magnetic resonance, crystallographic, and molecular modeling studies. Interligand Overhauser effects indicate that metformin can form ternary complexes with p-aminobenzoyl-l-glutamate (pABG) as well as other ligands that occupy the region of the folate-binding site that interacts with pABG; however, DHFR inhibition is not cooperative. The biguanides competitively inhibit the activity of ecDHFR, with the phenformin inhibition constant being 100-fold lower than that of metformin. This inhibition may be significant at concentrations present in the gut of treated individuals, and inhibition of DHFR in intestinal mucosal cells may also occur if accumulation levels are sufficient. Perturbation of folate homeostasis can alter the pyridine nucleotide redox ratios that are important regulators of cellular metabolism.

Transporters Involved in Metformin Pharmacokinetics and Treatment Response

Metformin, widely used as first-line treatment for type 2 diabetes, exists primarily as a hydrophilic cation at physiological pHs. As such, membrane transporters play a substantial role in its absorption, tissues distribution, and renal elimination. Multiple organic cation transporters are determinants of the pharmacokinetics of metformin, and many of them are important in its pharmacological action, as mediators of metformin entry into target tissues. Furthermore, a recent genome-wide association study in a large multi-ethnic population implicated polymorphisms in SLC2A2, encoding the glucose transporter, GLUT2, as important determinants of response to metformin. Here, we describe the key transporters associated with metformin pharmacokinetics and response.

Anti-tumor effects of metformin on head and neck carcinoma cell lines: A systematic review

Metformin is commonly used for treating type 2 diabetes, and may also reduce cancer risk. Previous studies have demonstrated the association between metformin use and a decreased risk of head and neck cancer. Therefore, the aim of the present systematic review was to summarize the available literature on the in vitro anti-tumor effects of metformin on head and neck squamous cell carcinoma (HNSCC). Research studies were obtained from Cochrane Library, Embase, LILACS, MEDLINE and PubMed databases, without time or language restrictions. Only in vitro studies analyzing the effects of metformin on HNSCC cell lines were included. The authors methodically appraised all the selected studies according to the Grading of Recommendations Assessment, Development and Evaluation method to make a judgment of the evidence quality. Of the 388 identified reports, 11 studies met the inclusion criteria and were used for qualitative analysis. These studies demonstrated that metformin is important in inhibiting cell proliferation, inducing G0/G1 cell cycle arrest and apoptosis, and in regulating proteins involved in carcinogenesis pathways, which corroborates its potential in vitro anti-tumor effects. The present systematic review highlights the biological mechanisms of metformin used alone or together with traditional therapies for cancer. Though very limited, currently available preclinical evidence shows that metformin exerts a potential effect on head and neck carcinoma.

Effects of melatonin and metformin co-administration on testicular ischemia/reperfusion injury in rats

INTRODUCTION

Torsion of the spermatic cord is a common urologic emergency among infants and adolescents. It requires early diagnosis and surgical intervention to prevent subfertility and infertility.

OBJECTIVE

The aim of this study was to investigate the effects of melatonin (MEL) and metformin (MET) co-administration on experimental testicular ischemia/reperfusion (I/R) injury in rats.

MATERIAL AND METHODS

Fifty male Wistar rats were randomly divided into five experimental groups (n = 10), as follows. Group 1 was sham operated. In group 2, 1-hour ischemia was induced by the left testicular artery and vein clipping followed by 7 days of reperfusion. In groups 3 and 4, MEL (3 mg/kg) or MET (100 mg/kg) was administered orally for 7 days via oral gavage after ischemia, and in group 5 both agents were co-administered. At the end of trial, the left testis was removed for histological analysis and oxidative stress measurement. Histological findings in seminiferous tubule were evaluated according to Johnsen's scoring system.

RESULTS

I/R reduced superoxide dismutase (SOD) activities and testicular Johnsen's scores accompanied by an elevation in malondialdehyde (MDA) and myeloperoxidase (MPO) levels (p < 0.05). MEL and MET, and their combination restored SOD activity, tissue scores, MDA and MPO levels (p < 0.05). There was no significant difference among individual or combined treatment of these parameters (p > 0.05).

DISCUSSION

In the present experiment, using a rat model it has been demonstrated that testicular I/R caused a significant increase in testicular injuries. This was in accordance with previous studies that have demonstrated the effect of I/R in testicular tissue. Treatment of MEL and MET had a benefit effect, but, there was no significant difference among individual or combined treatment.

CONCLUSIONS

The results of the present study suggest that MEL and MET may be useful for protecting the testes from the I/R injury. However, the combined use of these agents does not further increase the protection from this damage.

Increased chitotriosidase activity in plasma of patients with type 2 diabetes

INTRODUCTION

Chitotriosidase (CHIT1) is a chitinolytic enzyme involved mainly in the immune and inflammatory response. It shows increased activity in many pathologies, including in newly diagnosed type 2 diabetes (T2D). This study aimed to investigate this enzyme's activity in plasma of patients with ongoing T2D and indicate factors related to the increased activity of this enzyme.

MATERIAL AND METHODS

Ninety-one patients and 46 control subjects without abnormalities in carbohydrate metabolism and inflammatory states were enrolled in the study. Plasma CHIT1 activity was measured by a spectrofluorometric method. Routine laboratory parameters such as blood glucose, total cholesterol and HDL fraction, triglyceride, glycated hemoglobin, white blood cell count and C-reactive protein were measured by standard methods.

RESULTS

We found that the chitotriosidase activity was significantly higher (p < 0.001) in type 2 diabetic patients and positively associated with parameters of glycemic control (levels of glucose and glycated hemoglobin) and blood pressure. Plasma glucose level and systolic blood pressure were independent determinants of increased CHIT1 activity in T2D patients, even after adjustment for disease duration, body mass index, parameters of inflammation and lipid metabolism. We also found that increased CHIT1 activity was associated with occurrence of diabetic angiopathies.

CONCLUSIONS

This investigation indicates a possible role of chitotriosidase in the course of T2D, especially in relation to development of diabetic angiopathies.

Metformin protects against infection-induced myocardial dysfunction

BACKGROUND AND PURPOSE

Metformin administration is associated with myocardial protection during ischemia and/or reperfusion, possibly via inhibition of inflammatory responses in the heart. Exposure to pathogens, in addition to the activation of the immune system and the associated metabolic dysfunction, often results in compromised myocardial function. We examined whether metformin administration could maintain the normal myocardial function in experimental moderate Gram negative infection, induced by lipopolysaccharide (LPS) administration.

EXPERIMENTAL APPROACH

129xC57BL/6 mice were divided into control groups that received either vehicle or a single intraperitoneal (i.p.) injection of low dose LPS (5mg/kg body wt), and metformin treated groups that received either daily metformin (4mg/kg/animal) i.p. injections for five days prior to LPS administration [Experiment 1], or a single metformin injection following same dose of LPS [Experiment 2].

KEY RESULTS

LPS alone caused cardiac dysfunction, as confirmed by echocardiography, whereas metformin administration, either before or after LPS, rescued myocardial function. LPS caused marked reduction of the cardiac metabolism-related genes tested, including Prkaa2, Cpt1b, Ppargc1a and Ppargc1b; reduction of fatty acid oxidation, as reflected by the regulation of Ppara, Acaca and Acacb; increased glucose transport, as shown by Slc2a4 levels; reduction of ATP synthesis; significant increase of inflammatory markers, in particular IL6; and reduction of autophagy. Pretreatment with metformin normalized the levels of all these factors.

CONCLUSIONS AND IMPLICATIONS

We show for the first time that metformin protects the myocardium from LPS-associated myocardial dysfunction mainly by supporting its metabolic activity and allowing efficient energy utilization. Metformin can be a potential cardioprotective agent in individuals susceptible to exposure to pathogens.

Non-alcoholic fatty liver disease is associated with insulin resistance and lipid accumulation product in women with polycystic ovary syndrome

STUDY QUESTION

What are the most relevant factors associated with non-alcoholic fatty liver disease (NAFLD) in women with polycystic ovary syndrome (PCOS)?

SUMMARY ANSWER

Insulin resistance (IR) and lipid accumulation product (LAP) are independently associated with NAFLD in PCOS.

WHAT IS KNOWN ALREADY

Obesity and IR are frequently present in both women with PCOS and subjects having NAFLD. The coexistence of PCOS and NAFLD might synergistically increase the risk for both type 2 diabetes (T2DM) and cardiovascular disease (CVD). LAP, calculated from waist circumference (WC) and triglycerides (TGs) concentrations [(WC-58) × TGs], has been shown to represent an integrated marker of cardiometabolic risk in women with PCOS.

STUDY DESIGN, SIZE, DURATION

This cross-sectional study included 600 Caucasian women diagnosed with PCOS by the Rotterdam criteria between May 2008 and May 2013.

PARTICIPANTS, SETTINGS, METHODS

The study was done at the university hospitals in Belgrade, Serbia and Thessaloniki, Greece. All subjects underwent anthropometric measurements and analyses of fasting blood glucose, insulin, lipids, total testosterone and SHBG, as well as liver tests (transaminases, γ-glutamyltransaminase, total bilirubin and alkaline phosphatase). Calculations for a NAFLD liver fat score (NAFLD-LFS) (with, accordingly, determination of metabolic syndrome and testing for T2DM) as well as homeostasis model assessment of IR (HOMA-IR), LAP as a marker of visceral adiposity, and free androgen index (FAI) were performed. We evaluated the prevance of NAFLD and analyzed associations of the above variables with NAFLD.

MAIN RESULTS AND THE ROLE OF CHANCE

NAFLD was more prevalent in patients with PCOS than in controls (50.6 versus 34.0%, respectively). Women with PCOS had higher readings for WC, LAP, insulin and HOMA-IR, total cholesterol and TGs than controls (P < 0.001). In PCOS women, the NAFLD-LFS significantly (P < 0.001) correlated with WC, BMI, glucose, HOMA-IR, TGs, LAP and FAI. In multivariate logistic regression, HOMA-IR and LAP were independently associated with NAFLD (P ≤ 0.001).

LIMITATIONS, REASONS FOR CAUTION

A possible weakness of the study may be the absence of structural confirmation of liver status. Hovewer, liver biopsy is invasive, difficult to perform in large populations and carries some risk of complications while magnetic resonance spectroscopy does not provide any information regarding the presence of fibrosis and is not routinely available. Another possible limitation could be the measurement of total testosterone by radioimmunoassay, which can be inaccurate when determining low levels of testosterone. Finally, fewer controls than subjects in the study group could have affected the significance of the results.

WIDER IMPLICATIONS OF THE FINDINGS

There is a debate on the most accurate clinical method for diagnosing liver disease as an early predictor of T2DM and CVD in general population and in PCOS women. There current study provided data on this issue from a cohort of Caucasian women with PCOS.

STUDY FUNDING/COMPETING INTERESTS

The study was supported by a research grant by the Serbian Ministry of Science and Education (grant nos 41009 and 175032). All authors have no competing interests.

Options for empagliflozin in combination therapy in type 2 diabetes mellitus

Objective

To update clinicians with an overview of empagliflozin for the treatment of type 2 diabetes mellitus (T2DM), with focus on use in combination regimens.

Methods

Keyword searches were conducted in the Medline database to identify literature reporting clinical trials of at least 12 weeks’ duration using empagliflozin treatment in patients with T2DM.

Results

When given as monotherapy or in combination therapy (as add-on or single-pill therapy) with metformin, pioglitazone, sulfonylurea, linagliptin, and insulin, empagliflozin produced clinically meaningful reductions in glycated hemoglobin levels, plasma glucose concentrations, bodyweight, and blood pressure. These changes were sustained during long-term treatment. In a dedicated cardiovascular event trial, empagliflozin on top of standard of care demonstrated a significant reduction in the risk of cardiovascular mortality and all-cause mortality. Across the clinical trials, empagliflozin combination therapies were well tolerated, and empagliflozin used alone was not associated with increased risk of hypoglycemia versus placebo. Indeed, the combination of empagliflozin and metformin had a significantly reduced rate of hypoglycemia compared with the combination of metformin and a sulfonylurea. On the other hand, empagliflozin treatment did have increased risk of genital infections compared with placebo. In clinical trials to date, diabetic ketoacidosis was not seen more frequently with empagliflozin than with placebo, but physicians should be alert to the possibility of this rare event.

Conclusion

Empagliflozin has the potential to make an important contribution to the treatment of patients with T2DM. In some patients, empagliflozin may be used as monotherapy, but it is most likely to be used in combination with other therapies. Given the reduced risk of mortality seen when empagliflozin was added to standard care in patients at high cardiovascular risk, as well as the lack of alternative options for patients at lower cardiovascular risk, empagliflozin may be added to ongoing regimens for a significant proportion of patients.

Effects of metformin and sitagliptin on glycolipid metabolism in type 2 diabetic rats on different diets

INTRODUCTION

The aim of the study was to investigate the effects of metformin and sitagliptin on glycolipid metabolism in type 2 diabetes after different diets.

MATERIAL AND METHODS

Seventy Male Sprague Dawley rats were fed with a high fat diet followed by streptozotocin treatment to induce type 2 diabetes. Then all rats were randomly divided into a control group, a metformin group (200 mg/kg), and a sitagliptin group (10 mg/kg). Each group was further divided into 4 groups receiving one load of high carbohydrate diet (45% glucose, 4.5 ml/kg), high fat diet (20% lipid emulsion, 4.5 ml/kg), high protein diet (20% whey protein, 10 ml/kg) or mixed meal, respectively. The caloric densities were all 33 kJ/kg. Postprandial blood glucose (P2BG), triglyceride (TG), glucagon-like peptide-1 (GLP-1), glucagon and insulin levels were measured.

RESULTS

In the high carbohydrate group, sitagliptin was more efficient in lowering P2BG compared with metformin (p < 0.05). In the high-fat group, metformin was more powerful in lowering TG (p < 0.05) and P2BG (p < 0.05) levels because of its improvement of insulin sensitivity. In the high protein diet group, metformin did not reduce the P2BG level (p > 0.05), although it did reduce the TG level (p < 0.05). In the mixed diet group, metformin was more efficient in lowering P2BG (p < 0.05) but had a similar effect on TG (p > 0.05) compared with sitagliptin.

CONCLUSIONS

In the type 2 diabetic model, metformin and sitagliptin have different effects on glycolipid metabolism after different diets. If it is proved in type 2 diabetic patients, then different medicines may be recommended according to different diets in order to improve glycolipid metabolism.

Exendin-4 enhances expression of Neurod1 and Glut2 in insulin-producing cells derived from mouse embryonic stem cells

INTRODUCTION

Stem cells involved cell replacement therapies for type 1 diabetes mellitus is promising, yet time-consuming and inefficient. Exendin-4 is a glucagon-like peptide-1 (GLP-1) receptor agonist which has been reported to possess anti-apoptotic effects, thereby increasing β-cell mass and improving β-cell function. The present study aimed to investigate whether exendin-4 would enhance the differentiation of embryonic stem cells into insulin-secreting cells and improve the pancreatic differentiation strategy.

MATERIAL AND METHODS

R1 embryonic stem cells were treated with different concentrations of exendin-4 and divided into three groups. In the high dosage group (group H), exendin-4 was added at the dosage of 10 nmol/l. In the low dosage group (group L), exendin-4 was added at the dosage of 0.1 nmol/l. Group C was a control. Expression of genes related to the β-cell phenotype and immunofluorescence staining of insulin and C-peptide were detected.

RESULTS

Compared with groups L and C, group H had the highest mRNA expression levels of Isl1, Pdx1, Ngn3, and Insulin1 (p < 0.05). Neurod1 and Glut2 only emerged at the final stage of differentiation in group H. Immunofluorescence analysis revealed that exendin-4 upregulated the protein expression of insulin and C-peptide.

CONCLUSIONS

Exendin-4 remarkably facilitated Neurod1 and Glut2 gene transcription, and was able to induce differentiation of embryonic stem cells into endocrine and insulin-producing cells.

Current topics on inhibitors of respiratory complex I

There are a variety of chemicals which regulate the functions of bacterial and mitochondrial complex I. Some of them, such as rotenone and piericidin A, have been indispensable molecular tools in mechanistic studies on complex I. A large amount of experimental data characterizing the actions of complex I inhibitors has been accumulated so far. Recent X-ray crystallographic structural models of entire complex I may be helpful to carefully interpret this data. We herein focused on recent hot topics on complex I inhibitors and the subjects closely connected to these inhibitors, which may provide useful information not only on the structural and functional aspects of complex I, but also on drug design targeting this enzyme. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt.

Breast Cancer Metabolism and Mitochondrial Activity: The Possibility of Chemoprevention with Metformin

Metabolic reprogramming refers to the ability of cancer cells to alter their metabolism in order to support the increased energy request due to continuous growth, rapid proliferation, and other characteristics typical of neoplastic cells. It has long been believed that the increase of metabolic request was independent of the mitochondrial action but recently we know that mitochondrial activity together with metabolism plays a pivotal role in the regulation of the energy needed for tumor cell growth and proliferation. For these reasons the mitochondria pathways could be a new target for therapeutic and chemopreventive intervention. Metformin in particular is actually considered a promising agent against mitochondrial activity thanks to its ability to inhibit the mitochondrial complex I.

Mechanism of Altered Metformin Distribution in Nonalcoholic Steatohepatitis

Metformin is an antihyperglycemic drug that is widely prescribed for type 2 diabetes mellitus and is currently being investigated for the treatment of nonalcoholic steatohepatitis (NASH). NASH is known to alter hepatic membrane transporter expression and drug disposition similarly in humans and rodent models of NASH. Metformin is almost exclusively eliminated through the kidney primarily through active secretion mediated by Oct1, Oct2, and Mate1. The purpose of this study was to determine how NASH affects kidney transporter expression and metformin pharmacokinetics. A single oral dose of [(14)C]metformin was administered to C57BL/6J (wild type [WT]) and diabetic ob/ob mice fed either a control diet or a methionine- and choline-deficient (MCD) diet. Metformin plasma concentrations were slightly increased in the WT/MCD and ob/control groups, whereas plasma concentrations were 4.8-fold higher in ob/MCD mice compared with WT/control. The MCD diet significantly increased plasma half-life and mean residence time and correspondingly decreased oral clearance in both genotypes. These changes in disposition were caused by ob/ob- and MCD diet-specific decreases in the kidney mRNA expression of Oct2 and Mate1, whereas Oct1 mRNA expression was only decreased in ob/MCD mice. These results indicate that the diabetic ob/ob genotype and the MCD disease model alter kidney transporter expression and alter the pharmacokinetics of metformin, potentially increasing the risk of drug toxicity.

Sulfonylureas and their use in clinical practice

Many anti-diabetic drugs with different mechanisms of action are now available for treatment of type 2 diabetes mellitus. Sulfonylureas have been extensively used for treatment of type 2 diabetes for nearly 50 years and, even in our times, are widely used for treatment of this devastating chronic illness. Here, we review some of the available data on sulfonylureas, evaluating their mechanism of action and their effects on glycemic control. We can conclude that sulfonylureas are still the most used anti-diabetic agents: maybe this is due to their lower cost, to the possibility of mono-dosing and to the presence of an association with metformin in the same tablet. However, sulfonylureas, especially the older ones, are linked to a greater prevalence of hypoglycemia, and cardiovascular risk; newer prolonged-release preparations of sulfonylureas are undoubtedly safer, mainly due to reducing hypoglycemia, and for this reason should be preferred.

Diagnosis and management of cardiovascular risk in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is increasingly recognized as an important cardiovascular risk (CVR) factor. This is a narrative clinical review aimed at answering how diagnosis and management of CVR should be conducted in the individual patient with NAFLD. To this end, the authors performed an extensive search of the existing literature on PubMed (1993-2014) using pertinent keywords. To date, CVR among patients with NAFLD might be assessed with the Framingham risk score equation or other risk calculators, to be adapted to the true CVR in the specific population being assessed; however, the use of these CVR calculators needs to be validated by future studies in larger cohorts of NAFLD patients of various ethnic backgrounds in order to substantiate their clinical relevance as a foundation for the primary prevention of cardiovascular diseases in this group of patients. Early and aggressive drug treatment of CVR should be started in NAFLD patients with a history of cardiovascular events, established diabetes or who are at high (calculated) CVR. Whether such an aggressive pharmacological approach is also justified in patients with NAFLD, who are at intermediate or low CVR, remains debatable. Currently, there are no clinical trials showing that the treatment of NAFLD per se (either associated or unassociated with traditional CVR factors) will result in decreased risk of cardiovascular events. Accordingly, drug treatment should be better individualized, aiming at correcting all the coexisting cardio-metabolic risk factors of the individual patient with NAFLD. To this end, an overview of the lifestyle interventions and the available drugs is offered, emphasis being conveyed to statins and metformin, which promise to cover worrying complications of NAFLD such as the risk of developing hepatocellular carcinoma.

Metformin protects primary rat hepatocytes against oxidative stress-induced apoptosis

The majority of chronic liver diseases are accompanied by oxidative stress, which induces apoptosis in hepatocytes and liver injury. Recent studies suggest that oxidative stress and insulin resistance are important in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and the pathophysiology of diabetes complications. Metformin has been shown to be hepatoprotective in the insulin-resistant and leptin-deficient ob/ob mouse model of NAFLD. However, the mechanism involved in the protective effects of metformin has not been elucidated yet. Therefore, we investigated the protective effect of metformin against oxidative stress-induced apoptosis. Primary rat hepatocytes were exposed to the oxidative stress-generating compound menadione in the presence and absence of metformin. Apoptosis was determined by measuring caspase activity and poly(ADP-ribose) polymerase (PARP)-cleavage, and necrosis was measured by Sytox Green nuclear staining. We demonstrate that (1) Metformin inhibits menadione-induced caspase-9,-6,-3 activation and PARP-cleavage in a concentration-dependent manner. (2) Metformin increases menadione-induced heme oxygenase-1 (HO-1) expression and inhibits c-Jun N-terminal kinase (JNK)-phosphorylation. (3) Metformin does not induce necrosis in primary hepatocytes. Metformin protects hepatocytes against oxidative stress-induced caspase activation, PARP-cleavage and apoptosis. The anti-apoptotic effect of metformin is in part dependent on HO-1 and bcl-xl induction and inhibition of JNK activation and independent of insulin signaling. Our results elucidate novel protective mechanisms of metformin and indicate that metformin could be investigated as a novel therapeutic agent for the treatment of oxidative stress-related liver diseases.