Metformin: An Old Drug for the Treatment of Diabetes but a New Drug for the Protection of the Endothelium

Nitrosamine mitigation: NDMA impurity formation and its inhibition in metformin hydrochloride tablets

The mitigation of nitrosamine formation in drug products has been studied and approaches such as using formulations with pH modifiers and antioxidants have been shown to decrease the formation of nitrosamines. However, more studies are needed to explore the effectivness of mitigation strategies with different drug models and formulations. The primary objective of this work was to assess the role of different antioxidants and pH modifiers in tablet formulations to mitigate the formation of NDMA, prepared in-house, using metformin hydrochloride as a model drug. A study design for manufacturing metformin hydrochloride formulations was created to evaluate potential mitigation stratigies. The formulations were prepared by wet granulation that included a sodium nitrite spike and various antioxidants such as ascorbic acid, caffeic acid and ferulic acid at various concentrations that may inhibit nitrosamine formation. The study design also included pH modifiers such as hydrochloric acid and sodium carbonate. The metformin hydrochloride formulations were placed under stability conditions that included humidity, temperature and time over a six month period. NDMA inhibition was found to be most effective in formulations with basic pH, followed by the addition of tested antioxidants with 0.1% concentrations in the formulations. All tested antioxidants showed complete mitigation in formulations with 0.5% and 1% concentrations. In summary, basic pH and the inclusion of antioxidants exhibited the potential to mitigate the formation of NDMA in metformin hydrochloride tablets.

Metformin: Beyond Type 2 Diabetes Mellitus

Metformin was developed from an offshoot of Guanidine. It is known to be the first-line medication for type 2 diabetes mellitus, polycystic ovarian syndrome, and weight reduction. Metformin has also been shown to have effectiveness in the management of non-alcoholic fatty liver disease (NAFLD), liver cirrhosis, and various carcinomas like hepatocellular, colorectal, prostate, breast, urinary bladder, blood, melanoma, bone, skin, lung and so on. This narrative review focuses on the effect of metformin on non-alcoholic fatty liver disease, liver cirrhosis, and hepatocellular carcinoma. The search platforms for the topic were PubMed, Scopus, and Google search engine. Critical words for searching included 'Metformin,' AND 'Indications of Metformin,' AND 'Non-Alcoholic Fatty Liver Disease,' AND 'Metformin mechanism of action,' AND 'NAFLD management,' AND 'NAFLD and inflammation,' AND 'Metformin and insulin,' AND 'Metformin and inflammation,' AND 'Liver cirrhosis,' AND 'Hepatocellular carcinoma.' Lifestyle modification and the use of hypoglycemic agents can help improve liver conditions. Metformin has several mechanisms that enhance liver health, including reducing reactive oxygen species, nuclear factor kappa beta (NF-κB), liver enzymes, improving insulin sensitivity, and improving hepatic cell lipophagy. Long-term use of metformin may cause some adverse effects like lactic acidosis and gastrointestinal disturbance. Metformin long-term overdose may lead to a rise in hydrogen sulfide in liver cells, which calls for pharmacovigilance. Drug regulating authorities should provide approval for further research, and national and international guidelines need to be developed for liver diseases, perhaps with the inclusion of metformin as part of the management regime.

Cardiovascular Effectiveness and Safety of Antidiabetic Drugs in Patients with Type 2 Diabetes and Peripheral Artery Disease: Systematic Review

Peripheral artery disease (PAD) is an atherosclerotic condition commonly complicating type 2 diabetes (T2D), leading to poor quality of life and increased risk of major adverse lower-limb (MALE) and cardiovascular (CV) events (MACE). Therapeutic management of PAD in T2D patients is much more arduous, often due to bilateral, multi-vessel, and distal vascular involvement, in addition to increased systemic polyvascular atherosclerotic burden. On the other hand, the pathophysiological link between PAD and T2D is very complex, involving mechanisms such as endothelial dysfunction and increased subclinical inflammation in addition to chronic hyperglycemia. Therefore, the clinical approach should not ignore vascular protection with the aim of reducing limb and overall CV events besides a mere glucose-lowering effect. However, the choice of the best medications in this setting is challenging due to low-grade evidence or lacking targeted studies in PAD patients. The present review highlighted the strong relationship between T2D and PAD, focusing on the best treatment strategy to reduce CV risk and prevent PAD occurrence and worsening in patients with T2D. The Medline databases were searched for studies including T2D and PAD up to June 2024 and reporting the CV effectiveness and safety of the most used glucose-lowering agents, with no restriction on PAD definition, study design, or country. The main outcomes considered were MACE-including nonfatal acute myocardial infarction, nonfatal stroke, and CV death-and MALE-defined as lower-limb complications, amputations, or need for revascularization. To the best of our current knowledge, GLP-1 receptor agonists and SGLT2 inhibitors represent the best choice to reduce CV risk in T2D and PAD settings, but a personalized approach should be considered. GLP-1 receptor agonists should be preferred in subjects with prevalent atherosclerotic burden and a history of previous MALE, while SGLT2 inhibitors should be used in those with heart failure if overall CV benefits outweigh the risk of lower-limb complications.

Preeclampsia: A comprehensive review

Preeclampsia (PE) is a life-threatening disease of pregnancy and a prominent cause of neonatal and maternal mortality and morbidity. PE affects approximately 5-10% of pregnancies worldwide, posing significant risks to perinatal and maternal health. It is characterized by a variety of interconnected pathological cascades contributing to the stimulation of intravascular inflammation, oxidative stress (OS), endothelial cell activation, and syncytiotrophoblast stress that converge on a common pathway, ultimately resulting in disease progression. The present study was designed and executed to review the existing scientific literature, specifically focusing on the etiology (gestational diabetes mellitus and maternal obesity, insulin resistance, metabolic syndrome, maternal infection, periodontal disease, altered microbiome, and genetics), clinical presentations (hypertension, blood disorders, proteinuria, hepatic dysfunction, renal dysfunction, pulmonary edema, cardiac dysfunction, fetal growth restrictions, and eclampsia), therapeutic clinical biomarkers (creatinine, albuminuria, and cystatin C) along with their associations and mechanisms in PE. In addition, this study provides insights into the potential of nanomedicines for targeting these mechanisms for PE management and treatment. Inflammation, OS, proteinuria, and an altered microbiome are prominent biomarkers associated with progression and PE-related pathogenesis. Understanding the molecular mechanisms, exploring suitable markers, targeted interventions, comprehensive screening, and holistic strategies are critical to decreasing the incidence of PE and promoting maternal-fetal well-being. The present study comprehensively reviewed the etiology, clinical presentations, therapeutic biomarkers, and preventive potential of nanomedicines in the treatment and management of PE.

Exploring the Biological Effects of Anti-Diabetic Vanadium Compounds in the Liver, Heart and Brain

The prevalence of diabetes mellitus and diabetes-related complications is rapidly increasing worldwide, placing a substantial financial burden on healthcare systems. Approximately 537 million adults are currently diagnosed with type 1 or type 2 diabetes globally. However, interestingly, the increasing morbidity rate is primarily influenced by the effects of long-term hyperglycemia on vital organs such as the brain, the liver and the heart rather than the ability of the body to use glucose effectively. This can be attributed to the summation of the detrimental effects of excessive glucose on major vascular systems and the harmful side effects attributed to the current treatment associated with managing the disease. These drugs have been implicated in the onset and progression of cardiovascular disease, hepatocyte injury and cognitive dysfunction, thereby warranting extensive research into alternative treatment strategies. Literature has shown significant progress in utilizing metal-based compounds, specifically those containing transition metals such as zinc, magnesium and vanadium, in managing hyperglycaemia. Amongst these metals, research carried out on vanadium reflected the most promising anti-diabetic efficacy in cell culture and animal studies. This was attributed to the ability to improve glucose management in the bloodstream by enhancing its uptake and metabolism in the kidney, brain, skeletal muscle, heart and liver. Despite this, organic vanadium was considered toxic due to its accumulative characteristics. To alleviate vanadium's toxic nature while subsequently manipulating its therapeutic properties, vanadium complexes were synthesized using either vanadate or vanadyl as a base compound. This review attempts to evaluate organic vanadium salts' therapeutic and toxic effects, highlight vanadium complexes' research and provide insight into the novel dioxidovanadium complex synthesized in our laboratory to alleviate hyperglycaemia-associated macrovascular complications in the brain, heart and liver.

Advances in metformin-delivery systems for diabetes and obesity management

Metformin is a medication that is commonly prescribed to manage type 2 diabetes. It has been used for more than 60 years and is highly effective in lowering blood glucose levels. Recent studies indicate that metformin may have additional medical benefits beyond treating diabetes, revealing its potential therapeutic uses. Oral medication is commonly used to administer metformin because of its convenience and cost-effectiveness. However, there are challenges in optimizing its effectiveness. Gastrointestinal side effects and limitations in bioavailability have led to the underutilization of metformin. Innovative drug-delivery systems such as fast-dissolving tablets, micro/nanoparticle formulations, hydrogel and microneedles have been explored to optimize metformin therapy. These strategies enhance metformin dosage, targeting, bioavailability and stability, and provide personalized treatment options for improved glucose homeostasis, antiobesity and metabolic health benefits. Developing new delivery systems for metformin shows potential for improving therapeutic outcomes, broadening its applications beyond diabetes management and addressing unmet medical needs in various clinical settings. However, it is important to improve drug-delivery systems, addressing issues such as complexity, cost, biocompatibility, stability during storage and transportation, loading capacity, required technologies and biomaterials, targeting precision and regulatory approval. Addressing these limitations is crucial for effective, safe and accessible drug delivery in clinical practice. In this review, recent advances in the development and application of metformin-delivery systems for diabetes and obesity are discussed.

Brazil nut (Bertholletia excelsa) and metformin abrogate cardiac complication in fructose/STZ-induced type 2 diabetic rats by attenuating oxidative stress and modulating the MAPK-mTOR/NFkB/IL-10 signaling pathways

Background

The global prevalence of diabetic heart complication has been on the increase, and some of the drugs that are currently used to treat diabetes mellitus (DM) have not been able to mitigate this complication.

Objective

This study determines the effect of Brazil nut (Bertholletia excelsa) and metformin on diabetic cardiomyopathy (DCM) in fructose/streptozotocin (STZ)-induced type 2 diabetic rats and also characterizes using Gas Chromatography Mass Spectrophotometry and Fourier Transform Infrared the bioactive compounds in 50% aqueous ethanol extract of Brazil nut.

Design

After inducing type 2 DM, 30 male albino Wistar rats were separated into five groups that comprised of six rats per group, and they were treated as follows: groups 1 (Control) and 2 (Diabetic control) rats received rat pellets and distilled water; group 3 (Diabetic + Brazil nut) received rat pellets and Brazil nut extract (100 mg/kg, orally) dissolved in distilled water, group 4 (Diabetic + metformin) received metformin (100 mg/kg, orally) dissolved in distilled water, while group 5 (Diabetic + Brazil nut + metformin) received oral administrations of Brazil nut (100 mg/kg) and metformin (100 mg/kg) dissolved in distilled water. This study lasted for 6 weeks. The dose of Brazil nut used was selected from our pilot study on the minimum therapeutic dose of different concentrations of Brazil nut extract.

Results

STZ administration induced insulin resistance, hyperglycemia, loss of weight, dyslipidemia, oxidative stress, inflammation, apoptosis, alteration of mammalian target of rapamycin, mitogen-activated protein kinase, heart function markers (creatine kinase MB, lactate dehydrogenase, and aspartate amino transaminase), and heart histology of the diabetic control, which was ameliorated after treatment with Brazil nut and metformin, but their combined treatment was better than the single treatments.

Conclusion

This study shows that Brazil nut contains several bioactive compounds that support its biological properties as well as its candidature as a complementary therapy to metformin in mitigating cardiac complications arising from DM in rats.

Occurrence, removal, and prioritization of organic micropollutants in four full-scale wastewater treatment plants in Korea

This study investigated the occurrence, removal rate, and potential risks of 43 organic micropollutants (OMPs) in four municipal wastewater treatment plants (WWTPs) in Korea. Results from two-year intensive monitoring confirmed the presence of various OMPs in the influents, including pharmaceuticals such as acetaminophen (pain relief), caffeine (stimulants), cimetidine (H2-blockers), ibuprofen (non-steroidal anti-inflammatory drugs- NSAIDs), metformin (antidiabetics), and naproxen (NSAIDs) with median concentrations of >1 μg/L. Some pharmaceuticals (carbamazepine-anticonvulsants, diclofenac-NSAIDs, propranolol-β-blockers), corrosion inhibitors (1H-benzotriazole-BTR, 4-methyl-1H-benzotriazole-4-TTR), and perfluorinated compounds (PFCs) were negligibly removed during WWTP treatment. The OMP concentrations in the influents and effluents were mostly lower in August than those of other months (p-value <0.05) possibly due to wastewater dilution by high precipitation or enhanced biodegradation under high-temperature conditions. The anaerobic-anoxic-oxic process (A2O) with a membrane bioreactor exhibited higher OMP removal than other processes, such as A2O with sedimentation or the conventional activated sludge process (p-value <0.05). Pesticides (DEET and atrazine), corrosion inhibitors (4-TTR and BTR), and metformin were selected as priority OMPs in toxicity-driven prioritization, whereas PFCs were determined as priority OMPs given their persistence and bioaccumulation properties. Overall, our results contribute to an important database on the occurrence, removal, and potential risks of OMPs in Korean WWTPs.

Metformin attenuates high-carbohydrate diet-induced redox imbalance, inflammation, and mitochondrial dysfunction in Megalobrama amblycephala

This study aimed to investigate the effects of dietary metformin supplementation on the redox balance, inflammation, mitochondrial biogenesis, and function in blunt snout bream fed a high-carbohydrate (HC) diet. Fish (45.12 ± 0.36 g) were randomly offered four diets, including a control diet (33% carbohydrate), an HC diet (45% carbohydrate), and the HC diet supplemented with 0.06% (HCM1) and 0.12% (HCM2) metformin respectively for 12 weeks. Compared with the control, feeding the HC diet significantly increased the hepatosomatic index (HSI), the mesenteric fat index, liver and muscle glycogen contents, liver and adipose tissue lipid contents, plasma glucose and glycation end products (AGES) levels and aspartate transaminase activity, plasma and liver malondialdehyde (MDA) contents, hepatic adenosine triphosphate (ATP) and adenosine monophosphate (AMP) contents, mitochondrial cytochrome c content, mitochondrial complex IV activity and ATP 6 transcription, but decreased plasma catalase (CAT) activity, muscle superoxide dismutase (SOD) activity, hepatic antioxidant enzymes activities, and the transcriptions of transforming growth factor β (tgfβ) and interleukin 10 (il10). Compared with the HC group, metformin treatment (especially the HCM2 group) significantly elevated tissue glycogen contents, muscle SOD activity, plasma and liver antioxidant enzymes activities, the transcriptions of tgfβ and il10, the sodium/potassium ATPase activity, the contents of mitochondrial protein and AMP, the level of p-AMP activated protein kinase (AMPK), and the p-AMPK/t-AMPK ratio, but lowered the HSI, tissue lipid contents, plasma levels of glucose, AGES and glycated serum protein, plasma, and liver MDA contents, the transcriptions of il1β, NADH dehydrogenase subunit 1 and ATP 6, the contents of ATP and cytochrome c, the ATP/AMP ratio, and the activities of complexes I and IV. In conclusion, metformin could attenuate the HC diet-induced redox imbalance, inflammation, and mitochondrial dysfunction in blunt snout bream.

Energy Metabolism and Metformin: Effects on Ischemia-Reperfusion Injury in Kidney Transplantation

Metformin (MTF) is the only biguanide included in the World Health Organization's list of essential medicines; representing a widespread drug in the management of diabetes mellitus. With its accessibility and affordability being one of its biggest assets, it has become the target of interest for many trying to find alternative treatments for varied pathologies. Over time, an increasing body of evidence has shown additional roles of MTF, with unexpected interactions of benefit in other diseases. Metformin (MTF) holds significant promise in mitigating ischemia-reperfusion injury (IRI), particularly in the realm of organ transplantation. As acceptance criteria for organ transplants expand, IRI during the preservation phase remain a major concern within the transplant community, prompting a keen interest in MTF's effects. Emerging evidence suggests that administering MTF during reperfusion may activate the reperfusion injury salvage kinase (RISK) pathway. This pathway is pivotal in alleviating IRI in transplant recipients, potentially leading to improved outcomes such as reduced rates of organ rejection. This review aims to contextualize MTF historically, explore its current uses, pharmacokinetics, and pharmacodynamics, and link these aspects to the pathophysiology of IRI to illuminate its potential future role in transplantation. A comprehensive survey of the current literature highlights MTF's potential to recondition and protect against IRI by attenuating free radical damage, activating AMP-activated protein kinase to preserve cellular energy and promote repair, as well as directly reducing inflammation and enhancing microcirculation.

Repurposing Metformin for the Treatment of Atrial Fibrillation: Current Insights

Metformin is an orally effective anti-hyperglycemic drug that despite being introduced over 60 years ago is still utilized by an estimated 120 to 150 million people worldwide for the treatment of type 2 diabetes (T2D). Metformin is used off-label for the treatment of polycystic ovary syndrome (PCOS) and for pre-diabetes and weight loss. Metformin is a safe, inexpensive drug with side effects mostly limited to gastrointestinal issues. Prospective clinical data from the United Kingdom Prospective Diabetes Study (UKPDS), completed in 1998, demonstrated that metformin not only has excellent therapeutic efficacy as an anti-diabetes drug but also that good glycemic control reduced the risk of micro- and macro-vascular complications, especially in obese patients and thereby reduced the risk of diabetes-associated cardiovascular disease (CVD). Based on a long history of clinical use and an excellent safety record metformin has been investigated to be repurposed for numerous other diseases including as an anti-aging agent, Alzheimer's disease and other dementias, cancer, COVID-19 and also atrial fibrillation (AF). AF is the most frequently diagnosed cardiac arrythmia and its prevalence is increasing globally as the population ages. The argument for repurposing metformin for AF is based on a combination of retrospective clinical data and in vivo and in vitro pre-clinical laboratory studies. In this review, we critically evaluate the evidence that metformin has cardioprotective actions and assess whether the clinical and pre-clinical evidence support the use of metformin to reduce the risk and treat AF.

Free radical scavenging polyphenols isolated from Phyllanthus niruri L. ameliorates hyperglycemia via SIRT1 induction and GLUT4 translocation in in vitro and in vivo models

Type 2 diabetes milletus (T2DM) is a complex multifaceted disorder characterized by insulin resistance in skeletal muscle. Phyllanthus niruri L. is well reported sub-tropical therapeutically beneficial ayurvedic medicinal plant from Euphorbiaceae family used in various body ailments such as metabolic disorder including diabetes. The present study emphasizes on the therapeutic potential of Phyllanthus niruri L. and its phytochemical(s) against insulin resistance conditions and impaired antioxidant activity thereby aiding as an anti-hyperglycemic agent in targeting T2DM. Three compounds were isolated from the most active ethyl acetate fraction namely compound 1 as 1-O-galloyl-6-O-luteoyl-β-D-glucoside, compound 2 as brevifolincarboxylic acid and compound 3 as ricinoleic acid. Compounds 1 and 2, the two polyphenols enhanced the uptake of glucose and inhibited ROS levels in palmitate induced C2C12 myotubes. PNEAF showed the potent enhancement of glucose uptake in palmitate-induced insulin resistance condition in C2C12 myotubes and significant ROS inhibition was observed in skeletal muscle cell line. PNEAF treated IR C2C12 myotubes and STZ induced Wistar rats elevated SIRT1, PGC1-α signaling cascade through phosphorylation of AMPK and GLUT4 translocation resulting in insulin sensitization. Our study revealed an insight into the efficacy of marker compounds isolated from P. niruri and its enriched ethyl acetate fraction as ROS scavenging agent and helps in attenuating insulin resistance condition in C2C12 myotubes as well as in STZ induced Wistar rat by restoring glucose metabolism. Overall, this study can provide prospects for the marker-assisted development of P. niruri as a phytopharmaceutical drug for the insulin resistance related diabetic complications.

Patient In-Use Stability Testing of FDA-Approved Metformin Combination Products for N-Nitrosamine Impurity

Between February 2020 and January 2022, the Food and Drug Administration (FDA) recalled 281 metformin extended-release products due to the presence of N-nitrosodimethylamine (NDMA) above the acceptable daily intake (ADI, 96 ng/day). Our previous studies indicated presence of NDMA levels above ADI in both metformin immediate and extended-release products. When metformin products have NDMA impurities, it is indispensable to check for the same impurities in metformin combination products. Therefore, the objective of the present study was to evaluate in-use stability of commercial metformin combination products for NDMA. For this purpose, metformin products in combination with glyburide (GB1-GB12), glipizide (GP1-GP8), pioglitazone (P1-P3), alogliptin (A1, A2), and linagliptin (L1, L2) were repacked in pharmacy vials, stored at 30°C/75% RH for 3 months, and monitored for NDMA impurity. The NDMA level varied from 0 to 156.8 ± 32.8 ng/tablet initially and increased to 25.4 ± 5.1 to 455.0 ± 28.4 ng/tablet after 3 months of exposure to in-use condition. Initially, 18 products have NDMA level below ADI limit before exposure which decreased to 7 products (GB5, GP3, GP5, A1, A2, L1, and L2) meeting specification. In conclusion, in-use stability study provides quality and safety risk assessment of drug products where nitroso impurities are detected in the probable condition of use.

Developmental metformin exposure does not rescue physiological impairments derived from early exposure to altered maternal metabolic state in offspring mice

OBJECTIVE

The incidence of gestational diabetes mellitus (GDM) and metabolic disorders during pregnancy are increasing globally. This has resulted in increased use of therapeutic interventions such as metformin to aid in glycemic control during pregnancy. Even though metformin can cross the placental barrier, its impact on offspring brain development remains poorly understood. As metformin promotes AMPK signaling, which plays a key role in axonal growth during development, we hypothesized that it may have an impact on hypothalamic signaling and the formation of neuronal projections in the hypothalamus, the key regulator of energy homeostasis. We further hypothesized that this is dependent on the metabolic and nutritional status of the mother at the time of metformin intervention. Using mouse models of maternal overnutrition, we aimed to assess the effects of metformin exposure on offspring physiology and hypothalamic neuronal circuits during key periods of development.

METHODS

Female C57BL/6N mice received either a control diet or a high-fat diet (HFD) during pregnancy and lactation periods. A subset of dams was fed a HFD exclusively during the lactation. Anti-diabetic treatments were given during the first postnatal weeks. Body weights of male and female offspring were monitored daily until weaning. Circulating metabolic factors and molecular changes in the hypothalamus were assessed at postnatal day 16 using ELISA and Western Blot, respectively. Hypothalamic innervation was assessed by immunostaining at postnatal days 16 and 21.

RESULTS

We identified alterations in weight gain and circulating hormones in male and female offspring induced by anti-diabetic treatment during the early postnatal period, which were critically dependent on the maternal metabolic state. Furthermore, hypothalamic agouti-related peptide (AgRP) and proopiomelanocortin (POMC) neuronal innervation outcomes in response to anti-diabetic treatment were also modulated by maternal metabolic state. We also identified sex-specific changes in hypothalamic AMPK signaling in response to metformin exposure.

CONCLUSION

We demonstrate a unique interaction between anti-diabetic treatment and maternal metabolic state, resulting in sex-specific effects on offspring brain development and physiological outcomes. Overall, based on our findings, no positive effect of metformin intervention was observed in the offspring, despite ameliorating effects on maternal metabolic outcomes. In fact, the metabolic state of the mother drives the most dramatic differences in offspring physiology and metformin had no rescuing effect. Our results therefore highlight the need for a deeper understanding of how maternal metabolic state (excessive weight gain versus stable weight during GDM treatment) affects the developing offspring. Further, these results emphasize that the interventions to treat alterations in maternal metabolism during pregnancy need to be reassessed from the perspective of the offspring physiology.

Combined Administration of Metformin and Vitamin D: A Futuristic Approach for Management of Hyperglycemia

Diabetes is a series of metabolic disorders that can be categorized into three types depending on different aspects associated with age at onset, intensity of insulin resistance, and beta- cell dysfunction: Type 1 and 2 Diabetes, and Gestational Diabetes Mellitus. Type 2 Diabetes Mellitus (T2DM) has recently been found to account for more than 85% of diabetic cases. The current review intends to raise awareness among clinicians/researchers that combining vitamin D3 with metformin may pave the way for better T2DM treatment and management. An extensive literature survey was performed to analyze vitamin D's role in regulating insulin secretion, their action on the target cells and thus maintaining the normal glucose level. On the other side, the anti-hyperglycemic effect of metformin as well as its detailed mechanism of action was also studied. Interestingly both compounds are known to exhibit the antioxidant effect too. Literature supporting the correlation between diabetic phenotypes and deficiency of vitamin D was also explored further. To thoroughly understand the common/overlapping pathways responsible for the antidiabetic as well as antioxidant nature of metformin and vitamin D3, we compared their antihyperglycemic and antioxidant activities. With this background, we are proposing the hypothesis that it would be of great interest if these two compounds could work in synergy to better manage the condition of T2DM and associated disorders.

Neuronanomedicine for Alzheimer's and Parkinson's disease: Current progress and a guide to improve clinical translation

Neuronanomedicine is an emerging multidisciplinary field that aims to create innovative nanotechnologies to treat major neurodegenerative disorders, such as Alzheimer's (AD) and Parkinson's disease (PD). A key component of neuronanomedicine are nanoparticles, which can improve drug properties and demonstrate enhanced safety and delivery across the blood-brain barrier, a major improvement on existing therapeutic approaches. In this review, we critically analyze the latest nanoparticle-based strategies to modify underlying disease pathology to slow or halt AD/PD progression. We find that a major roadblock for neuronanomedicine translation to date is a poor understanding of how nanoparticles interact with biological systems (i.e., bio-nano interactions), which is partly due to inconsistent reporting in published works. Accordingly, this review makes a set of specific recommendations to help guide researchers to harness the unique properties of nanoparticles and thus realise breakthrough treatments for AD/PD.

Diclofenac and metformin synergistic dose dependent inhibition of hamster fibrosarcoma, rescued with mebendazole

We examined whether combinig diclofenac and metformin in doses equivalent to human doses would synergize their anticancer activity on fibrosarcoma inoculated to hamsters and in vitro. Rescue experiment was performed to examine whether the prosurvival NF-κB stimulation by mebendazole can reverse anticancer effects of the treatment. BHK-21/C13 cell culture was subcutaneously inoculated to Syrian golden hamsters randomly divided into groups (6 animals per group): 1) untreated control; treated daily with 2) diclofenac; 3) metformin; 4) combinations of diclofenac and metformin at various doses; 5) combination of diclofenac, metformin and mebendazole; 6) mebendazole. Dose response curves were made for diclofenac and metformin combination. Tumor growth kinetics, biophysical, pathological, histological and immunohistochemical characteristics of excised tumors and hamster organs as well as biochemical and hematological blood tests were compared among the groups. Single treatments had no anticancer effects. Diclofenac (60 mg/kg/day) exhibited significant (P < 0.05) synergistic inhibitory effect with metformin (500 mg/kg/day) on all tumor growth parameters, without toxicity and influence on biochemical and hematological blood tests. The same results were obtained with double doses of diclofenac and metformin combination. The addition of mebendazole to the diclofenac and metformin combination rescued tumor expansion. Furthermore, diclofenac with metformin demonstrated antiproliferative effects in hamster fibrosarcoma BHK-21/C13, human lung carcinoma A549 (CCL-185), colon carcinoma HT-29 (HTB-38) and cervical carcinoma HeLa (CCL-2) cell cultures, with markedly lower cytotoxicity in the normal fetal lung MRC-5 cells. In conclusion, diclofenac and metformin combination may be recommended for potential use in oncology, due to synergistic anticancer effect in doses achievable in humans.

Small-Molecule Loaded Biomimetic Biphasic Scaffold for Osteochondral Regeneration: An In Vitro and In Vivo Study

Osteoarthritis is a prevalent musculoskeletal disorder in the elderly, which leads to high rates of morbidity. Mesenchymal stem cells (MSCs) are a promising approach to promote tissue regeneration in the absence of effective long-term treatments. Small molecules are relatively inexpensive and can selectively alter stem cell behavior during their differentiation, making them an attractive option for clinical applications. In this study, we developed an extracellular matrix (ECM)-based biphasic scaffold (BPS) loaded with two small-molecule drugs, kartogenin (KGN) and metformin (MET). This cell-free biomimetic biphasic scaffold consists of a bone (gelatin/hydroxyapatite scaffold embedded with metformin [GHSM]) and cartilage (nano-gelatin fiber embedded with kartogenin [NGFK]) layer designed to stimulate osteochondral regeneration. Extracellular matrix (ECM)-based biomimetic scaffolds can promote native cell recruitment, infiltration, and differentiation even in the absence of additional growth factors. The biphasic scaffold (BPS) showed excellent biocompatibility in vitro, with mesenchymal stem cells (MSCs) adhering, proliferating, and differentiated on the biomimetic biphasic scaffolds (GHSM and NGFK layers). The biphasic scaffolds upregulated both osteogenic and chondrogenic gene expression, sulfated glycosaminoglycan (sGAG), osteo- and chondrogenic biomarker, and relative mRNA gene expression. In an in vivo rat model, histo-morphological staining showed effective regeneration of osteochondral defects. This novel BPS has the potential to enhance both subchondral bone repair and cartilage regeneration, demonstrating excellent effects on cell homing and the recruitment of endogenous stem cells.

The antiproliferative potential and mechanism of action of metformin in MCF-7 cells

Aim

The current study aimed to investigate the potential antiproliferative activity of metformin, the effective concentration range, and the mechanism of action.

Materials & methods

Human breast cancer cells, MCF-7 were treated with a serial dilution of metformin (10-150 μM) for 24 and 48 h. Potential antiproliferative activity of metformin and its ability in inducing cellular apoptosis and autophagy were also investigated.

Results

Metformin inhibited MCF-7 proliferation in a concentration and time dependent manner, with 80 μM as the most effective concentration. Compared with nontreated cells, metformin induced significant levels of autophagy and apoptosis, which were confirmed by the reduction of mTOR and BCL-2 protein expression.

Conclusion

The study confirms the antiproliferative activity of metformin, which may likely occur through AMPK signaling pathway.

A Microstirring Oral Pill for Improving the Glucose-Lowering Effect of Metformin

Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia due to persistent insulin resistance, resulting in elevated blood glucose levels. Metformin is the most prescribed oral drug for lowering high blood glucose levels in T2DM patients. However, it is poorly absorbed and has low bioavailability. Here, we introduce magnesium-based microstirrers to a metformin-containing pill matrix to enhance the glucose-lowering effect of metformin. The resulting microstirring pill possesses a built-in mixing capability by creating local fluid transport upon interacting with biological fluid to enable fast pill disintegration and drug release along with accelerated metformin delivery. In vivo glucose tolerance testing using a murine model demonstrates that the metformin microstirring pill significantly improves therapeutic efficacy, lowering blood glucose levels after a meal more rapidly compared to a regular metformin pill without active stirring. As a result, the microstirrers allow for dose sparing, providing effective therapeutic efficacy at a lower drug dosage than passive metformin pills. These encouraging results highlight the versatility of this simple yet elegant microstirring pill technology, which enhances drug absorption after gastrointestinal delivery to improve therapeutic efficacy.

Encapsulation of Pioglitazone into Polymer-Nanoparticles for Potential Treatment of Atherosclerotic Diseases

Atherosclerosis is one of the most urgent global health subjects, causes millions of deaths worldwide, and is associated with enormous healthcare costs. Macrophages are the root cause for inflammatory onset and progression of the disease but are not addressed by conventional therapy. Therefore, we used pioglitazone, which is a drug initially used for diabetes therapies, but at the same time has great potential regarding the mitigation of inflammation. As yet, this potential of pioglitazone cannot be exploited, as drug concentrations at the target site in vivo are not sufficient. To overcome this shortcoming, we established PEG-PLA/PLGA-based nanoparticles loaded with pioglitazone and tested them in vitro. Encapsulation of the drug was analyzed by HPLC and revealed an outstanding encapsulation efficiency of 59% into the nanoparticles, which were 85 nm in size and had a PDI of 0.17. Further, uptake of our loaded nanoparticles in THP-1 macrophages was comparable to the uptake of unloaded nanoparticles. On the mRNA level, pioglitazone-loaded nanoparticles were superior to the free drug by 32% in increasing the expression of the targeted receptor PPAR-γ. Thereby the inflammatory response in macrophages was ameliorated. In this study, we take the first step toward an anti-inflammatory, causal antiatherosclerotic therapy, using the potential of the already established drug pioglitazone, and enable it to enrich at the target site by using nanoparticles. An additional crucial feature of our nanoparticle platform is the versatile modifiability of ligands and ligand density, to achieve an optimal active targeting effect in the future.

Taxifolin-3-O-glucoside from Osbeckia nepalensis Hook. mediates antihyperglycemic activity in CC1 hepatocytes and in diabetic Wistar rats via regulating AMPK/G6Pase/PEPCK signaling axis

ETHNOPHARMACOLOGICAL RELEVANCE

Osbeckia nepalensis Hook. f. is an ICMR documented plant well known for its antidiabetic uses among the folk people of Northeast Region of India. In-depth study with scientific substantiation of the plant may uphold the therapeutic potential against the treatment of type 2 diabetes mellitus (T2DM).

AIM OF THE STUDY

The present study evaluates the traditionally claimed prophylactic potential of O. nepalensis and its extracts along with the isolated compound taxifolin-3-O-glucoside (TG) against the downregulation of T2DM related hepatic gluconeogenesis through in vitro, in vivo and in silico conditions as a means of ameliorating hyperglycemia.

MATERIALS AND METHODS

Antidiabetic potential of O. nepalensis was carried out in both CC1 hepatocytes (in vitro) and STZ-induced diabetic male Wistar rats (in vivo). Enriched bioactive fraction and bioactive molecules were isolated through bioactivity-guided fractionation, yielding two major molecules, taxifolin-3-O-glucoside and quercitin-3-O-rhamnoside. The bioactivity of taxifolin-3-O-glucoside was validated through immunoblotting techniques aided by in silico molecular docking and simulations.

RESULTS

Methanolic extract of O. nepalensis and taxifolin-3-O-glucoside (TG) isolated thereof enhanced the uptake of glucose in CC1 hepatocytes and downregulates the gluconeogenic enzymes (G6Pase and PEPCK) and its related transcription factors (FOXO1, HNF4α and PGC1α) through the stimulation of AMPK phosphorylation in in vitro condition. Moreover, in in vivo experiments, the in vitro most active fraction BuSFr1 (consisting of the two active major compounds taxifolin-3-O-glucoside and quercitin-3-O-rhamnoside) exhibited a substantial decrease in elevated blood glucose level and increase the glucose tolerance as well as plasma insulin level. In silico molecular docking and simulations for TG with the protein G6Pase inferred the docking sites and stability and showed taxifolin-3-O-glucoside as more potent and non-toxic as compared to quercitin-3-O-rhamnoside.

CONCLUSION

The traditionally claimed antidiabetic effect of O. nepalensis has been proved to be effective in lowering the blood glucose level through in vitro, in vivo and in silico analysis which will pave a way for the development of antidiabetic phytopharmaceutical drugs which can be validated through further clinical studies.

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.

Metabolic modelling of the human gut microbiome in type 2 diabetes patients in response to metformin treatment

The human gut microbiome has been associated with several metabolic disorders including type 2 diabetes mellitus. Understanding metabolic changes in the gut microbiome is important to elucidate the role of gut bacteria in regulating host metabolism. Here, we used available metagenomics data from a metformin study, together with genome-scale metabolic modelling of the key bacteria in individual and community-level to investigate the mechanistic role of the gut microbiome in response to metformin. Individual modelling predicted that species that are increased after metformin treatment have higher growth rates in comparison to species that are decreased after metformin treatment. Gut microbial enrichment analysis showed prior to metformin treatment pathways related to the hypoglycemic effect were enriched. Our observations highlight how the key bacterial species after metformin treatment have commensal and competing behavior, and how their cellular metabolism changes due to different nutritional environment. Integrating different diets showed there were specific microbial alterations between different diets. These results show the importance of the nutritional environment and how dietary guidelines may improve drug efficiency through the gut microbiota.

An efficient removal approach for degradation of metformin from aqueous solutions with sulfate radicals

Metformin consumption for diabetes treatment is increasing, leading to its presence in wastewater treatment plants where conventional methods cannot remove it. Therefore, this work aims to analyze the performance of advanced oxidation processes using sulfate radicals in the degradation of metformin from water. Experiments were performed in a photoreactor provided with a low-pressure Hg lamp, using K₂S₂O₈ as oxidant and varying the initial metformin concentration (C_A0), oxidant concentration (C_ox), temperature (T), and pH in a response surface experimental design. The degradation percentages ranged from 26.1 to 87.3%, while the mineralization percentages varied between 15.1 and 64%. Analysis of variance (ANOVA) showed that the output variables were more significantly affected by C_A0, C_ox, and T. Besides, a reduction of C_A0 and an increase of C_ox up to 5000 μM maximizes the metformin degradation since the generation of radicals and their interaction with metformin molecules are favored. For the greatest degradation percentage, the first order apparent rate constant achieved was 0.084 min^-1. Furthermore, while in acidic pH, temperature benefits metformin degradation, an opposite behavior is obtained in a basic medium because of recombination and inhibition reactions. Moreover, three degradation pathways were suggested based on the six products detected by HPLC-MS: N-cyanoguanidine m/z = 85; N,N-dimethylurea m/z = 89; N,N-dimethyl-cyanamide m/z = 71 N,N-dimethyl-formamide m/z = 74; glicolonitrilo m/z = 58; and guanidine m/z = 60. Finally, it was shown that in general the toxicity of the degradation byproducts was lower than the toxicity of metformin toward Chlamydomonas reinhardtii.

Nanoparticle-Reinforced Tough Hydrogel as a Versatile Platform for Pharmaceutical Drug Delivery: Preparation and in Vitro Characterization

Natural polymer-based hydrogels are excellent for encapsulating hydrophilic drugs, but they are mechanically weak and degrade easily. In this communication, we exploit the electrostatic interaction between nanosilicates (nSi) and gelatin methacrylate (GelMA) to form a mechanically tough nanocomposite hydrogel for pharmaceutical drug delivery. These hydrogels, prepared at subzero temperatures to form cryogels, displayed macroporous structures, which favors cell infiltration. The designed tough cryogel also showed a slower rate of degradation. Furthermore, we encapsulated the small molecule metformin and sustained the drug release under physiological conditions. Cryogel-loaded metformin reduced the effect of endothelial cell injury caused by nutrient deprivation in vitro. Finally, we hypothesize that this versatile nanocomposite material will find use in diverse biomedical applications.

A positive feedback loop between AMPK and GDF15 promotes metformin antidiabetic effects

BACKGROUND AND AIMS

Metformin, the most prescribed drug for the treatment of type 2 diabetes mellitus, has been recently reported to promote weight loss by upregulating the anorectic cytokine growth differentiation factor 15 (GDF15). Since the antidiabetic effects of metformin are mostly mediated by the activation of AMPK, a key metabolic sensor in energy homeostasis, we examined whether the activation of this kinase by metformin was dependent on GDF15.

METHODS

Cultured hepatocytes and myotubes, and wild-type and Gdf15^-/- mice were utilized in a series of studies to investigate the involvement of GDF15 in the activation of AMPK by metformin.

RESULTS

A low dose of metformin increased GDF15 levels without significantly reducing body weight or food intake, but it ameliorated glucose intolerance and activated AMPK in the liver and skeletal muscle of wild-type mice but not Gdf15^-/- mice fed a high-fat diet. Cultured hepatocytes and myotubes treated with metformin showed AMPK-mediated increases in GDF15 levels independently of its central receptor GFRAL, while Gdf15 knockdown blunted the effect of metformin on AMPK activation, suggesting that AMPK is required for the metformin-mediated increase in GDF15, which in turn is needed to sustain the full activation of this kinase independently of the CNS.

CONCLUSION

Overall, these findings uncover a novel mechanism through which GDF15 upregulation by metformin is involved in achieving and sustaining full AMPK activation by this drug independently of the CNS.

Metformin adherence and the risk of cardiovascular disease: a population-based cohort study

Background

Metformin is a potent antiglycemic agent, but its importance has receded owing to the launch of novel antidiabetic medications. The benefit of metformin includes not only blood sugar control but also anti-inflammation, autophagy activation, and neuroprotection. This study investigated the risk of cardiovascular disease (CVD) in people with type II diabetes mellitus (T2DM) who adhered to metformin after adding on a second-line antiglycemic agent.

Objectives

The purpose of this study was to investigate the benefits of metformin in CVD prevention in patients with T2DM.

Design

We designed the study by comparing the incident rate of CVD events in patients with T2DM who received metformin continually and who ceased metformin during 2002-2014.

Methods

Medical information was obtained from the National Health Insurance Research Database, and patients with T2DM receiving second-line antiglycemic agents were categorized into metformin-adherent and nonadherent groups according to prescription claims. The study outcomes were the incidence of CVD hospitalization, including stroke (ischemic and hemorrhagic) and myocardial infarction (MI).

Results

A total of 31,384 patients with T2DM constituted the metformin-adherent group and were 1:1 matched to nonadherent patients. Metformin adherence was associated with a lower risk of hospitalization due to stroke [adjusted hazard ratio (aHR) = 0.51, 95% confidence interval (CI): 0.43-0.59, p < 0.001] and MI (aHR = 0.47, 95% CI: 0.43-0.53, p < 0.001). The risk reduction persisted in both ischemic and hemorrhagic strokes. Our subgroup analysis revealed that the protective effect on stroke and MI hospitalization persisted in metformin-adherent patients, both sexes, patients aged ⩽65 or >65 years, and patients with or without concurrent insulin treatment.

Conclusions

This study revealed that metformin adherence in patients with T2DM who required a first-line treatment may reduce the risk of subsequent CVD. Despite the availability of numerous novel antiglycemic agents, metformin adherence by patients who require a combination of antiglycemic agents provides an additional benefit of CVD protection.

Effect of metformin as an adjuvant therapy to letrozole on estradiol and other biomarkers involved in the pathogenesis of breast cancer in overweight and obese postmenopausal women: a pilot study

INTRODUCTION

Metformin may provide a therapeutic benefit in different types of malignancy.

PURPOSE

We aimed at evaluating the effect of metformin as an adjuvant therapy to letrozole on estradiol and other biomarkers involved in the pathogenesis of breast cancer in overweight and obese postmenopausal women.

METHODS

Seventy-five postmenopausal stages II-III breast cancer female patients were assessed for eligibility in an open-labeled parallel pilot study. Forty-five patients met the inclusion criteria and were assigned into three arms: the lean arm (n = 15) women who received letrozole 2.5 mg/day, the control arm (n = 15) overweight/obese women who received letrozole 2.5 mg/day, and the metformin arm (n = 15) overweight/obese women who received letrozole 2.5 mg/day plus metformin (2000 ± 500 mg/day). The intervention duration was 6 months. Blood samples were obtained at baseline and 6 months after intervention for the measurement of serum estradiol, leptin, osteocalcin levels, fasting blood glucose concentration, and serum insulin.

RESULTS

After the intervention and as compared to the control arm, the metformin arm showed a significantly lower ratio to the baseline (significant reduction) for estradiol (p = 0.0433), leptin (p < 0.0001), fasting blood glucose (p = 0.0128), insulin (p = 0.0360), osteocalcin serum levels (p < 0.0001), and the homeostatic model assessment of insulin resistance "HOMA-IR" value (p = 0.0145). There was a non-significant variation in the lactate ratio to the baseline among the three study arms (p = 0.5298).

CONCLUSION

Metformin may exert anti-cancer activity by decreasing the circulating estradiol, leptin, and insulin. Metformin might represent a safe and promising adjuvant therapy to letrozole in overweight/obese postmenopausal women with breast cancer.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05053841/Registered September 23, 2021 - Retrospectively.

Metformin's Impact on the Microvascular Response to Insulin

Metformin improves insulin's action on whole-body glucose metabolism in various insulin-resistant populations. The detailed cellular mechanism(s) for its metabolic actions are multiple and still incompletely understood. Beyond metabolic actions, metformin also impacts microvascular function. However, the effects of metformin on microvascular function and microvascular insulin action specifically are poorly defined. In this mini-review, we summarize what is currently known about metformin's beneficial impact on both microvascular function and the microvascular response to insulin while highlighting methodologic issues in the literature that limit straightforward mechanistic understanding of these effects. We examine potential mechanisms for these effects based on pharmacologically dosed studies and propose that metformin may improve human microvascular insulin resistance by attenuating oxidative stress, inflammation, and endothelial dysfunction. Finally, we explore several important evidence gaps and discuss avenues for future investigation that may clarify whether metformin's ability to improve microvascular insulin sensitivity is linked to its positive impact on vascular outcomes.

From Diabetes to Atherosclerosis: Potential of Metformin for Management of Cardiovascular Disease

Atherosclerosis is a common cause of cardiovascular disease, which, in turn, is often fatal. Today, we know a lot about the pathogenesis of atherosclerosis. However, the main knowledge is that the disease is extremely complicated. The development of atherosclerosis is associated with more than one molecular mechanism, each making a significant contribution. These mechanisms include endothelial dysfunction, inflammation, mitochondrial dysfunction, oxidative stress, and lipid metabolism disorders. This complexity inevitably leads to difficulties in treatment and prevention. One of the possible therapeutic options for atherosclerosis and its consequences may be metformin, which has already proven itself in the treatment of diabetes. Both diabetes and atherosclerosis are complex metabolic diseases, the pathogenesis of which involves many different mechanisms, including those common to both diseases. This makes metformin a suitable candidate for investigating its efficacy in cardiovascular disease. In this review, we highlight aspects such as the mechanisms of action and targets of metformin, in addition to summarizing the available data from clinical trials on the effective reduction of cardiovascular risks.

Metformin: Is it a drug for all reasons and diseases?

Metformin was first used to treat type 2 diabetes in the late 1950s and in 2022 remains the first-choice drug used daily by approximately 150 million people. An accumulation of positive pre-clinical and clinical data has stimulated interest in re-purposing metformin to treat a variety of diseases including COVID-19. In polycystic ovary syndrome metformin improves insulin sensitivity. In type 1 diabetes metformin may help reduce the insulin dose. Meta-analysis and data from pre-clinical and clinical studies link metformin to a reduction in the incidence of cancer. Clinical trials, including MILES (Metformin In Longevity Study), and TAME (Targeting Aging with Metformin), have been designed to determine if metformin can offset aging and extend lifespan. Pre-clinical and clinical data suggest that metformin, via suppression of pro-inflammatory pathways, protection of mitochondria and vascular function, and direct actions on neuronal stem cells, may protect against neurodegenerative diseases. Metformin has also been studied for its anti-bacterial, -viral, -malaria efficacy. Collectively, these data raise the question: Is metformin a drug for all diseases? It remains unclear as to whether all of these putative beneficial effects are secondary to its actions as an anti-hyperglycemic and insulin-sensitizing drug, or result from other cellular actions, including inhibition of mTOR (mammalian target for rapamycin), or direct anti-viral actions. Clarification is also sought as to whether data from ex vivo studies based on the use of high concentrations of metformin can be translated into clinical benefits, or whether they reflect a 'Paracelsus' effect. The environmental impact of metformin, a drug with no known metabolites, is another emerging issue that has been linked to endocrine disruption in fish, and extensive use in T2D has also raised concerns over effects on human reproduction. The objectives for this review are to: 1) evaluate the putative mechanism(s) of action of metformin; 2) analyze the controversial evidence for metformin's effectiveness in the treatment of diseases other than type 2 diabetes; 3) assess the reproducibility of the data, and finally 4) reach an informed conclusion as to whether metformin is a drug for all diseases and reasons. We conclude that the primary clinical benefits of metformin result from its insulin-sensitizing and antihyperglycaemic effects that secondarily contribute to a reduced risk of a number of diseases and thereby enhancing healthspan. However, benefits like improving vascular endothelial function that are independent of effects on glucose homeostasis add to metformin's therapeutic actions.

Meroterpenoids containing benzopyran or benzofuran motif from Ganoderma cochlear

Five undescribed benzopyran containing meroterpenoids, ganodercins Q－U, two undescribed benzofuran containing meroterpenoids, ganodercins V and W, and two known meroterpenoids were isolated from Ganoderma cochlear. Their structures were elucidated by using HRESIMS, NMR spectroscopy and computational methods. The results of biochemical studies using a palmitic acid (PA) induced insulin resistance (IR) model show that (-)-ganodercin Q, (+)-ganodercins R and W activate phospho-AKT (p-AKT) at 20 μM and improve glucose uptake in a concentration dependent manner. The results of renoprotection studies show that (+)-ganodercin S, cochlearol F, (+)- and (-)-ganodercins V reduce the expression of collagen I.

The role of AMPK-dependent pathways in cellular and molecular mechanisms of metformin: a new perspective for treatment and prevention of diseases

Metformin can suppress gluconeogenesis and reduce blood sugar by activating adenosine monophosphate-activated protein kinase (AMPK) and inducing small heterodimer partner (SHP) expression in the liver cells. The main mechanism of metformin's action is related to its activation of the AMPK enzyme and regulation of the energy balance. AMPK is a heterothermic serine/threonine kinase made of a catalytic alpha subunit and two subunits of beta and a gamma regulator. This enzyme can measure the intracellular ratio of AMP/ATP. If this ratio is high, the amino acid threonine 172 available in its alpha chain would be activated by the phosphorylated liver kinase B1 (LKB1), leading to AMPK activation. Several studies have indicated that apart from its significant role in the reduction of blood glucose level, metformin activates the AMPK enzyme that in turn has various efficient impacts on the regulation of various processes, including controlling inflammatory conditions, altering the differentiation pathway of immune and non-immune cell pathways, and the amelioration of various cancers, liver diseases, inflammatory bowel disease (IBD), kidney diseases, neurological disorders, etc. Metformin's activation of AMPK enables it to control inflammatory conditions, improve oxidative status, regulate the differentiation pathways of various cells, change the pathological process in various diseases, and finally have positive therapeutic effects on them. Due to the activation of AMPK and its role in regulating several subcellular signalling pathways, metformin can be effective in altering the cells' proliferation and differentiation pathways and eventually in the prevention and treatment of certain diseases.

Analysis of missense SNPs in the SLC47A1 and SLC47A2 genes affecting the pharmacokinetics of metformin: Computational approach

Background

Metformin as an anti-hyperglycaemic drug is commonly used for the treatment of type 2 diabetes mellitus (T2DM). The metformin response is variable due to the interindividual variation of pharmacokinetics which is based on strong genetic background. MATE1 and MATE2 proteins are significantly implicated in the pharmacokinetics of metformin. Missense SNPs with high risk of pathogenicity are expected to affect response to metformin via pharmacokinetics. Therefore, the aim of the current study is to determine the effects of missense SNPs in the SLC47A1 and SLC47A2 genes. The structural and functional consequences of all known SLC47A1 and SLC47A2 missense SNPs of the human MATE1 and MATE2 proteins were identified by various bioinformatics methods (SIFT, PhD-SNP, PolyPhen-2, PROVEAN, PMut, MUpro, I-Mutant 3.0, COACH, RaptorX Binding, ConSurf, STRING).

Results

The SLC47A1 variants P186T, L116P and the SLC47A2 variants I158N, L112P, V118G exhibited ΔΔG values less than − 1 kcal/mol, and these variants are considered to disrupt the structure and function of MATE1 and MATE2 proteins. SLC47A1 R118Q and SLC47A2 Y273C, V118G may significantly disturb protein function and transporting activities according to the analysis of ligand-binding regions.

Conclusion

It is suggested that high-risk deleterious missense SNPs may mediate the pharmacokinetics of metformin and may be associated with altered tissue distribution, renal clearance and metformin toxicity. We suppose that our results might serve as potential targets for the studies composed of the development of potential diagnostic and therapeutic strategies based on the relationship between mutations and metformin response.

Metformin and the heart: Update on mechanisms of cardiovascular protection with special reference to comorbid type 2 diabetes and heart failure

Metformin has been in clinical use for the management of type 2 diabetes for more than 60 years and is supported by a vast database of clinical experience: this includes evidence for cardioprotection from randomised trials and real-world studies. Recently, the position of metformin as first choice glucose-lowering agent has been supplanted to some extent by the emergence of newer classes of antidiabetic therapy, namely the sodium-glucose co-transporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists. These agents have benefitted through support from large cardiovascular outcomes trials with more modern trial designs than earlier studies conducted to assess metformin. Nevertheless, clinical research on metformin continues to further assess its many potentially advantageous effects. Here, we review the evidence for improved cardiovascular outcomes with metformin in the context of the current era of diabetes outcomes trials. Focus is directed towards the potentially cardioprotective actions of metformin in patients with type 2 diabetes and heart failure (HF), now recognised as the most common complication of diabetes.

A comparative evaluation of cardiac and neurological safety status of two commonly used oral hypoglycaemic agents in T2-DM Swiss albino mice model

Background

Diabetes mellitus (DM), along with its associated complications, including diabetic neuropathy and hyperlipidemia, has become a global concern in the last few decades. The main objective of our study is to evaluate the comparative neuro-safety status, serum plasma glucose, and lipid-lowering potential of two widely recognized antidiabetic drugs named metformin and glimepiride.

Methods

The neurological evaluation was done by open field test, hole board test, forced swimming test, dark and lighthouse test, and elevated plus maze test by employing diazepam as standard. Serum blood glucose level of streptozotocin (STZ)-induced diabetic mice was determined by glucose oxidizing method using a glucometer. Total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and very-low-density lipoprotein cholesterol (VLDL-C) levels were estimated by using the reference method where atorvastatin was used as standard.

Results

In neurological evaluation, both drugs produce almost the same anxiolytic activity in the open field test, hole board test, light and dark house test, and elevated plus maze test. However, in the forced swimming test, glimepiride produced more antidepressant activity than metformin. Glimepiride was found to remarkably reduce serum glucose and VLDL-C levels more than metformin, whereas, for other parameters, metformin takes over glimepiride sometimes took over the standard atorvastatin.

Conclusions

The results of our study indicate that both oral hypoglycaemic drugs alter the lipid index while producing some anxiolytic effects on the central nervous system. Thus, recommended to be carefully administered to patients with low BMI and might be beneficial to patients suffering from peripheral nerve function and anxiety.

Transdermal Delivery of Metformin Using Dissolving Microneedles and Iontophoresis Patches for Browning Subcutaneous Adipose Tissue

Obesity is a serious public health problem that is strongly associated with increased multiple comorbidities such as diabetes, cardiovascular disease, and some types of cancer. While current anti-obesity treatments have various issues, locally transforming energy-storing white adipose tissue (WAT) into energy-burning brown-like/beige adipose tissue, the so-called browning of WAT, has been suggested to enhance obesity treatment efficiency with minimized side effects. Metformin is a first-line antidiabetes drug and a potent activator of AMP-activated protein kinase. Emerging evidence has suggested that metformin might enhance energy expenditure via the browning of WAT and hence reduce body weight. Subcutaneous WAT is easier to access and has a stronger browning potential than other WAT depots. In this study, we used dissolvable poly (lactic-co-glycolic acid) microneedles (MN) to deliver metformin to the subcutaneous WAT in obese C57BL/6J mice with the assistance of iontophoresis (INT), and then investigated metformin-induced WAT browning and its subsequent thermogenesis effects. Compared with MN alone or INT alone, MN + INT had better anti-obesity activity, as indicated by decreasing body weight and fat gain, increased energy expenditure, decreased fat pad size, and improved energy metabolism through the browning of WAT. Browning subcutaneous WAT by delivering metformin and other browning agents using this MN + INT approach might combat obesity in an effective, easy, and safe regimen.

Single Nucleotide Polymorphism in the 3' Untranslated Region of PRKAA2 on Cardiometabolic Parameters in Type 2 Diabetes Mellitus Patients Who Received Metformin

Purpose

This study aimed to explore the association of rs857148 A>C as 3'UTR variants with blood pressure, HbA1c profile, and lipid profiles as cardiometabolic parameters among patients with T2DM receiving metformin.

Patients and Methods

This cross-sectional analytic research was conducted with 114 consecutively selected patients with T2DM. Polymerase chain reaction-restriction fragment length polymorphism was conducted to determine rs857148. A total of 108 patients fulfilled inclusion and exclusion criteria.

Results

Genotype distribution agreed with the Hardy Weinberg Equation for Equilibrium (p>0.05) but wildtype allele was found as the minor allele. Subjects with CC genotype and C allele had enhanced HbA1c levels (OR=7.12; 95% CI=1.05-48.26; p=0.04; OR=1.66; 95% CI=1.06-2.60; p=0.03, respectively). It was confirmed by dominant model whereas subjects with AA tended to have reduced HbA1c compared to AC+CC genotype (OR=0.15; 95% CI=0.02-0.97; p=0.047). AC genotype had significant correlation to total cholesterol (OR=1.05; 95% CI=1.01-1.10; p=0.03) compared to AA genotype.

Conclusion

We conclude that polymorphism of rs87148, specifically CC genotype and C allele, has a significant association with HbA1c and total cholesterol after considering oral hypoglycemia agent dose, age, gender, and combination therapy, compared to AA genotype. Future studies that involve a larger sample population and more rigorous selection criteria are required.

Is the Duration of Diabetes Diseases Positively Associated With Knowledge About Diabetic Complications? Knowledge of Diabetes Mellitus Complications and Associated Factors Among Type-2 Diabetic Patients in Public Hospitals of Addis Ababa, 2020

Background

Although the importance of educational programs in the prevention and control of diabetes mellitus (DM) and its complication is well-recognized, there are concerns about whether these programs are achieving the desired goal of increasing knowledge of DM and its complication in developing countries. Therefore, this study assessed knowledge of DM complications and associated factors among type-2 diabetic patients in public hospitals of Addis Ababa.

Method

Simple random sampling technique was used to select 422 participants. Data were entered to EpiData Version 4.6.0.1 and analyzed using SPSS Version 25 software. Multicollinearity and model goodness-of-fit was checked. A multivariate logistic regression model at 95% CI was used to identify the predictors.

Result

The overall knowledge of diabetes complications among diabetic patients in the Hospitals of Addis Ababa was 54.9%. In the fitted model, being a profession of governmental workers [adjusted odds ratio (AOR) = 3.12, 95% CI (1.33, 7.34)] and merchants [AOR = 2.54, 95% CI (1.16, 5.56)]; DM duration 5–10 years [AOR = 0.41, 95% CI (0.23, 0.73)] and ≥10 years [AOR = 0.36, 95% CI (0.19, 0.69)]; family history of DM [AOR = 1.68, 95% CI (1.03, 2.75)]; and participating in diabetic counseling [AOR = 2.41, 95% CI (1.50, 3.86)] were significantly associated with knowledge about DM complications.

Conclusion and Recommendation

The overall knowledge of diabetes complications among diabetic patients in the Hospitals of Addis Ababa was 54.9%. It was determined by the duration of DM, current profession, family history, and participation in diabetes counseling. Hence, emphasis on sustaining knowledge about diabetes complications for patients who are more than 5 years since diagnosis and attention is needed about knowledge diabetic farmers.

Tofacitinib and metformin reduce the dermal thickness and fibrosis in mouse model of systemic sclerosis

Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway is important in the process of inflammation and fibrosis. The adenosine 5'-monophosphate-activated protein kinase (AMPK) enzyme can affect JAK/STAT pathway. Tofacitinib is a pan-JAK inhibitör. Metformin activates AMPK enzyme. We aimed to investigate the therapeutic efficacy of tofacitinib and metformin on IL-17 and TGF-β cytokines, skin fibrosis and inflammation in mouse model of systemic sclerosis (SSc). 40 Balb/c female mice were divided into 4 groups: (control, sham (BLM), tofacitinib and metformin). The mice in the tofacitinib group received oral tofacitinib (20 mg/kg/daily) and mice in the metformin group received oral metformin (50 mg/kg/day) for 28 days. At the end of 4th week, all groups of mice were decapitated and tissue samples were taken for analysis. Histopathological analysis of skin tissue was performed, and mRNA expressions of collagen 3A, IL-17 and TGF-β were assessed by real-time PCR and ELISA. Repeated BLM injections had induced dermal fibrosis. Moreover, the tissue levels of collagen 3A, IL-17 and TGF-β were elevated in the BLM group. Tofacitinib and metformin mitigated dermal fibrosis. They reduced dermal thickness and tissue collagen 3A, IL-17 and TGF-β levels. Tofacitinib and metformin demonstrated anti-inflammatory and anti-fibrotic effects in the mouse model of SSc.

Effects of metformin on human bone-derived mesenchymal stromal cell-breast cancer cell line interactions

Metformin is used to treat patients with type 2 diabetes mellitus and was found to lower the incidence of cancer. Bone metastasis is a common impairment associated with advanced breast cancer. The present study investigated the effects of metformin on human bone-derived mesenchymal stromal cells (BM-MSC)—breast cancer cell line interactions. BM-MSCs grown from box chisels were tested for growth-stimulating and migration-controlling activity on four breast cancer cell lines either untreated or after pretreatment with metformin. Growth stimulation was tested in MTT tests and migration in scratch assays. Furthermore, the expression of adipokines of BM-MSCs in response to metformin was assessed using Western blot arrays. Compared to breast cancer cell lines (3.6 ± 1.4% reduction of proliferation), 500 µM metformin significantly inhibited the proliferation of BM-MSC lines (mean 12.3 ± 2.2 reduction). Pretreatment of BM-MSCs with metformin showed variable effects of the resulting conditioned media (CM) on breast cancer cell lines depending on the specific BM-MSC—cancer line combination. Metformin significantly reduced the migration of breast cancer cell lines MDA-MB-231 and MDA-MB-436 in response to CM of drug-pretreated BM-MSCs. Assessment of metformin-induced alterations in the expression of adipokines by BM-MSC CM indicated increased osteogenic signaling and possibly impairment of metastasis. In conclusion, the anticancer activities of metformin are the result of a range of direct and indirect mechanisms that lower tumor proliferation and progression. A lower metformin-induced protumor activity of BM-MSCs in the bone microenvironment seem to contribute to the positive effects of the drug in selected breast cancer patients.

Metformin versus Silymarin as Hepatoprotective Agents in Mice Fibrotic Model Caused by Carbon Tetrachloride

OBJECTIVES

To study metformin hepatoprotective effects compared to silymarin on hepatic fibrosis caused by carbon tetrachloride (CCl4) in mice.

MATERIAL AND METHODS

liver fibrosis in mice was achieved by intraperitoneal injection of 2 ml/kg of CCl4 dilution in olive oil [1:9 (v/v)] twice a week for 7 weeks followed by oral treatment with metformin (250 mg/kg/day) or silymarin (100 mg/kg/day) (a standard hepatoprotective drug). The changes that follow liver fibrosis were assessed by measurement of hepatic enzymes (ALT, AST and ALP), histopathological examination using hematoxylin and eosin stain, special stains, and α-smooth muscle actin (α-SMA) immunostaining, measuring oxidative stress markers (MDA, GSH, NOx and MnSOD) and transforming growth factor-beta 1 (TGF-β1) in liver.

RESULTS

liver fibrosis was obviously developed in mice after intraperitoneal injection with CCl4 for 7 weeks. Both silymarin and metformin treatment exhibited a significant decrease in the fibrotic changes and similarly an increase in endogenous antioxidants. Interestingly there is a significant difference between silymarin and metformin regarding both efficacy and potency.

CONCLUSION

These findings highlight the anti-inflammatory, antioxidant and antifibrotic effects of metformin in CCl4-induced hepatic fibrosis in mice, but silymarin is more beneficial.

Biguanide Pharmaceutical Formulations and the Applications of Bile Acid-Based Nano Delivery in Chronic Medical Conditions

Biguanides, particularly the widely prescribed drug metformin, have been marketed for many decades and have well-established absorption profiles. They are commonly administered via the oral route and, despite variation in oral uptake, remain commonly prescribed for diabetes mellitus, typically type 2. Studies over the last decade have focused on the design and development of advanced oral delivery dosage forms using bio nano technologies and novel drug carrier systems. Such studies have demonstrated significantly enhanced delivery and safety of biguanides using nanocapsules. Enhanced delivery and safety have widened the potential applications of biguanides not only in diabetes but also in other disorders. Hence, this review aimed to explore biguanides’ pharmacokinetics, pharmacodynamics, and pharmaceutical applications in diabetes, as well as in other disorders.

Metformin-Incorporated Gelatin/Nano-Hydroxyapatite Scaffolds Promotes Bone Regeneration in Critical Size Rat Alveolar Bone Defect Model

In this study, we fabricated gelatin/nano-hydroxyapatite/metformin scaffold (GHMS) and compared its effectiveness in bone regeneration with extraction-only, Sinbone, and Bio-Oss Collagen^® groups in a critical size rat alveolar bone defect model. GHMS was synthesized by co-precipitating calcium hydroxide and orthophosphoric acid within gelatin solution, incorporating metformin, and cross-linked by microbial transglutaminase. The morphology, characterization, and biocompatibility of scaffold were examined. The in vitro effects of GHMS on osteogenic gene and protein expressions were evaluated. In vivo bone formation was assessed in a critical size rat alveolar bone defect model with micro-computed tomography and histological examination by comparing GHMS with extraction-only, Sinbone, and Bio-Oss Collagen^®. The synthesized GHMS had a highly interconnected porous structure with a mean pore size of 81.85 ± 13.8 µm. GHMS exhibited good biocompatibility; promoted ALPL, RUNX2, SP7, BGLAP, SPARC and Col1a1 gene expressions; and upregulated the synthesis of osteogenic proteins, including osteonectin, osteocalcin, and collagen type I. In critical size rat alveolar bone defects, GHMS showed superior bone regeneration compared to extraction-only, Sinbone, and Bio-Oss Collagen^® groups as manifested by greater alveolar ridge preservation, while more bone formation with a lower percentage of connective tissue and residual scaffold at the defect sites grafted with GHMS in histological staining. The GHMS presented in this study may be used as a potential bone substitute to regenerate alveolar bone. The good biocompatibility, relatively fast degradation, interconnected pores allowing vascularization, and higher bioactivity properties of the components of the GHMS (gelatin, nHA, and metformin) may contribute to direct osteogenesis.

Beneficial effects of a plant-fish oil, slow carbohydrate diet on cardio-metabolic health exceed the correcting effects of metformin-pioglitazone in diabetic pigs fed a fast-food diet

Background

Lifestyle influences endocrine, metabolic and cardiovascular homeostasis. This study investigated the impact of diet and oral anti-diabetic medication on cardio-metabolic health in human-sized diabetic pigs.

Methods

After a growing pre-phase from ~30 to ~69 kg during which domestic pigs were fed either a low fat, low sucrose diet (group A) or a fast food-type diet elevated in lard (15%) and sucrose (40%) (group B), the pigs were subdivided in 5 groups (n = 7–8 pigs per group). Group 1, normal pigs from group A on a low fat, low sugar (L) pig diet and group 2, normal pigs from group B on a high lard (25%), sucrose-fructose (40%), cholesterol (1%) fast food-type (F) diet. Diabetes (D) was induced in group B pigs by streptozotocin and group 3 received the F diet (DF), group 4 received the F diet with Anti-diabetic medication metformin (2 g.day^-1)-pioglitazone (40 mg.day^-1) (DFA) and group 5 switched to a Plant-Fish oil (25%), Slowly digestible starch (40%) diet (DPFS). The F and PFS diets were identical for fat, carbohydrate and protein content but only differed in fat and carbohydrate composition. The 5 pig groups were followed up for 7 weeks until reaching ~120 kg.

Results

In normal pigs, the F diet predisposed to several abnormalities related to metabolic syndrome. Diabetes amplified the inflammatory and cardiometabolic abnormalities of the F diet, but both oral FA medication and the PFS diet partially corrected these abnormalities (mean±SEM) as follows: Fasting plasma TNF-ɑ (pg.ml^-1) and NEFA (mmol.l^-1) concentrations were high (p<0.02) in DF (193±55 and 0.79±0.16), intermediate in DFA (136±40 and 0.57±012) and low in DPFS pigs (107±31 and 0.48±0.19). Meal intolerance (response over fasting) for glucose and triglycerides (area under the curve, mmol.h^-1) and for lactate (3-h postprandial, mmol.l^-1) was high (p<0.03) in DF (489±131, 8.6±4.8 and 2.2±0.6), intermediate in DFA (276±145, 1.4±1.1 and 1.6±0.4) and low in DPFS (184±62, 0.7±1.8 and 0.1±0.1). Insulin-mediated glucose disposal (mg.kg^-1.min^-1) showed a numerical trend (p = NS): low in DF (6.9±2.2), intermediate in DFA (8.2±1.3) and high in DPFS pigs (10.4±2.7). Liver weight (g.kg^-1 body weight) and liver triglyceride concentration (g.kg^-1 liver) were high (p<0.001) in DF (23.8±2.0 and 69±14), intermediate in DFA (21.1±2.0 and 49±15) and low in DPFS pigs (16.4±0.7 and 13±2.0). Aorta fatty streaks were high (p<0.01) in DF (16.4±5.7%), intermediate in DFA (7.4±4.5%) and low in DPFS pigs (0.05±0.02%).

Conclusion

This translational study using pigs with induced type 2 diabetes provides evidence that a change in nutritional life style from fast food to a plant-fish oil, slowly digestible starch diet can be more effective than sole anti-diabetic medication.

Urinary metabolites of type 2 diabetes rats fed with palm oil-enriched high fat diet

High fat diet (HFD) is one of the risk factors of obesity and diabetes. Recommended diet regimen for diabetes is difficult to abide by especially for HFD as it adds flavour to the taste buds. In this study, palm oil-enriched HFD and normal diet were fed to nicotinamide-induced type 2 diabetes rats, respectively for six weeks. Additionally, metformin, a common drug used to treat diabetes was given to rats under treatment groups. We evaluated the change of urinary metabolites of diabetes rats fed with palm oil-enriched HFD, and also after metformin treatment. Rats were divided into six-groups with different feeding diets, disease condition and with or without metformin treatment. Rats’ urine were collected at the end of six weeks feeding program and subjected to 1H-NMR and multivariate data analysis to evaluate their metabolite profiles. At the early phase of diabetes, metabolites changes in diabetic rats were associated with the disease itself. Our data showed that continuous consumption of HFD altered various metabolic pathways of diabetic rats and caused detrimental effects to the rats. On the other hand, metformin treatment combined with normal diet lessened the physiological impacts caused by diabetes condition.

Metformin Prevents Hyperglycemia-Associated, Oxidative Stress-Induced Vascular Endothelial Dysfunction: Essential Role for the Orphan Nuclear Receptor Human Nuclear Receptor 4A1 (Nur77)

Vascular pathology is increased in diabetes because of reactive-oxygen-species (ROS)-induced endothelial cell damage. We found that in vitro and in a streptozotocin diabetes model in vivo, metformin at diabetes-therapeutic concentrations (1-50 µM) protects tissue-intact and cultured vascular endothelial cells from hyperglycemia/ROS-induced dysfunction typified by reduced agonist-stimulated endothelium-dependent, nitric oxide-mediated vasorelaxation in response to muscarinic or proteinase-activated-receptor 2 agonists. Metformin not only attenuated hyperglycemia-induced ROS production in aorta-derived endothelial cell cultures but also prevented hyperglycemia-induced endothelial mitochondrial dysfunction (reduced oxygen consumption rate). These endothelium-protective effects of metformin were absent in orphan-nuclear-receptor Nr4a1-null murine aorta tissues in accord with our observing a direct metformin-Nr4a1 interaction. Using in silico modeling of metformin-NR4A1 interactions, Nr4a1-mutagenesis, and a transfected human embryonic kidney 293T cell functional assay for metformin-activated Nr4a1, we identified two Nr4a1 prolines, P505/P549 (mouse sequences corresponding to human P501/P546), as key residues for enabling metformin to affect mitochondrial function. Our data indicate a critical role for Nr4a1 in metformin's endothelial-protective effects observed at micromolar concentrations, which activate AMPKinase but do not affect mitochondrial complex-I or complex-III oxygen consumption rates, as does 0.5 mM metformin. Thus, therapeutic metformin concentrations requiring the expression of Nr4a1 protect the vasculature from hyperglycemia-induced dysfunction in addition to metformin's action to enhance insulin action in patients with diabetes. SIGNIFICANCE STATEMENT: Metformin improves diabetic vasodilator function, having cardioprotective effects beyond glycemic control, but its mechanism to do so is unknown. We found that metformin at therapeutic concentrations (1-50µM) prevents hyperglycemia-induced endothelial dysfunction by attenuating reactive oxygen species-induced damage, whereas high metformin (>250 µM) impairs vascular function. However, metformin's action requires the expression of the orphan nuclear receptor NR4A1/Nur77. Our data reveal a novel mechanism whereby metformin preserves diabetic vascular endothelial function, with implications for developing new metformin-related therapeutic agents.

Autophagy-mitophagy induction attenuates cardiovascular inflammation in a murine model of Kawasaki disease vasculitis

Kawasaki disease (KD) is the leading cause of acquired heart disease among children. Murine and human data suggest that the NLRP3-IL-1β pathway is the main driver of KD pathophysiology. NLRP3 can be activated during defective autophagy/mitophagy. We used the Lactobacillus casei cell wall extract (LCWE) murine model of KD vasculitis, to examine the role of autophagy/mitophagy on cardiovascular lesion development. LCWE-injected mice had impaired autophagy/mitophagy and increased levels of ROS in cardiovascular lesions, together with increased systemic 8-OHdG release. Enhanced autophagic flux significantly reduced cardiovascular lesions in LCWE-injected mice, whereas autophagy blockade increased inflammation. Vascular smooth muscle cell specific deletion of Atg16l1 and global Parkin-/- significantly increased disease formation, supporting the importance of autophagy/mitophagy in this model. Ogg1-/- mice had significantly increased lesions with increased NLRP3 activity, whereas treatment with MitoQ, reduced vascular tissue inflammation, ROS production and systemic 8-OHdG release. Treatment with MN58b or Metformin (increasing AMPK and reducing ROS), resulted in decreased disease formation. Our results demonstrate that impaired autophagy/mitophagy and ROS-dependent damage exacerbate the development of murine KD vasculitis. This pathway can be efficiently targeted to reduce disease severity. These findings enhance our understanding of KD pathogenesis and identify novel therapeutic avenues for KD treatment.