Metformin: the hidden chronicles of a magic drug

Applications of Metformin in Dentistry-A review

Metformin is a versatile drug with numerous medical uses. It is known primarily as an anti-hyperglycemic drug that has become the main oral blood-glucose-lowering medication for managing type 2 diabetes mellitus globally. Its use has been reported in a variety of oral conditions and dentistry in general. Recent clinical trials have indicated the effectiveness of adjunct topical application of metformin in improving the periodontal parameters of patients with diabetes and periodontitis. Additionally, studies have suggested that metformin stimulates odontogenic differentiation and mineral synthesis of stem cells in the tooth pulp. Metformin also stimulates osteoblast proliferation, decreases osteoclast activity and exerts regenerative effects on periodontal bone, thus making it a viable candidate for periodontal regeneration. Metformin monotherapy significantly enhances osseointegration of endosseous implants and has been reported to have anti-cancer effects on oral squamous cell carcinoma by impeding tumor progression. Animal studies have indicated that metformin improves orthodontic tooth movement and resists orthodontic appliance corrosion. This narrative review aims to provide a current summary of research highlighting the prospective uses of metformin in dentistry.

Regulation of the apoptosis/autophagy switch by propionic acid in ventromedial hypothalamus of rats with type 2 diabetes mellitus

Background

Hypothalamic dysregulation may cause abnormal glucose metabolism and type 2 diabetes mellitus (T2DM). The balance between autophagy and apoptosis is important for maintaining cellular/tissue homeostasis and may be disrupted in T2DM.

Objectives

Since propionic acid (PA) exerts neuroprotective effects, the aim was to investigate its effects on apoptosis/autophagy switch in the ventromedial hypothalamus (VMH) of T2DM rats.

Materials and methods

Male Wistar rats were divided: 1) control; 2) T2DM; groups that received (14 days, orally): 3) metformin (60 mg/kg); 4) sodium salt of PA (60 mg/kg); 5) PA + metformin. Western blotting (Bax, Bcl-xl, LC3, Beclin-1, caspase-3), RT-PCR (Bax, Bcl-xl, LC3, Beclin-1), transmission electron microscopy and immunohistochemical staining (Bax, Bcl-xl) were performed on the VMH samples.

Results

T2DM-induced apoptosis and mitoptosis, enlarged endoplasmic reticulum (ER) tubules/cisterns were observed in VMH, and accompanied by an imbalance of pro- and anti-apoptotic factors: elevation of pro-apoptotic markers Bax and caspase-3, decrease in autophagy protein LC3 and anti-apoptotic Bcl-xl. Metformin and PA administration partially improved VMH ultrastructural changes by reducing mitochondrial swelling and diminishing the number of apoptotic neurons. Metformin inhibited neuronal apoptosis, however, caused reactive astrogliosis and accumulation of lipofuscin granules. Elevated number of autophagosomes was associated with the LC3, Beclin-1 and Bcl-xl increase and decrease in Bax and caspase-3 vs. T2DM. PA switched cell fate from apoptosis to autophagy by elevating LC3 and Beclin-1 levels, increasing Bcl-xl content that altogether may represent adaptive response to T2DM-induced apoptosis. PA + metformin administration lowered relative area of ER membranes/cisterns vs. control, T2DM and metformin, and was optimal considering ratio between the pro-apoptotic, anti-apoptotic and autophagy markers.

Conclusion

T2DM was associated with apoptosis activation leading to impairments in VMH. PA in combination with metformin may be effective against diabetes-induced cell death by switching apoptosis to autophagy in VMH.

Cancer and Obesity: An Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) 2022

Background

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) provides an overview of cancer and increased body fat.

Methods

The scientific information for this CPS is based upon published scientific citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership.

Results

Topics include the increased risk of cancers among patients with obesity, cancer risk factor population-attributable fractions, genetic and epigenetic links between obesity and cancer, adiposopathic and mechanistic processes accounting for increased cancer risk among patients with obesity, the role of oxidative stress, and obesity-related cancers based upon Mendelian randomization and observational studies. Other topics include nutritional and physical activity principles for patients with obesity who either have cancer or are at risk for cancer, and preventive care as it relates to cancer and obesity.

Conclusions

Obesity is the second most common preventable cause of cancer and may be the most common preventable cause of cancer among nonsmokers. This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) on cancer is one of a series of OMA CPSs designed to assist clinicians in the care of patients with the disease of obesity. Patients with obesity are at greater risk of developing certain types of cancers, and treatment of obesity may influence the risk, onset, progression, and recurrence of cancer in patients with obesity.

Investigating the pro-cognitive and anti-depressant efficacy of metformin: A systematic review and meta-analysis of randomised controlled trials

BACKGROUND

The preclinical and clinical data regarding the efficacy of metformin as a pro-cognitive and anti-depressant therapy is mixed. We conducted a systematic review and meta-analysis of randomised controlled trials investigating the effects of metformin on cognition and depressive symptoms.

METHODS

The study was conducted in accordance with PRISMA guidelines (PROSPERO identifier: CRD42020184547). PubMed and Web of Science were searched (inception through to May 6, 2020) for trials which measured the effects (change from baseline to end-of-treatment) of metformin on cognition and depressive symptoms, compared to either placebo or other oral antidiabetic therapies. When feasible, pooled meta-analytic estimates were provided using a random-effects model.

RESULTS

Eight studies met the inclusion criteria: four assessed only cognition, three assessed only depressive symptoms, and one study assessed both cognition and depressive symptoms. Results suggested that metformin was significantly superior to placebo in improving cognitive function in patients suffering with clinical conditions associated with cognitive impairment (SMD: 0.80; 95%CI: 0.46 to 1.15; p < 0.001; N = 2 studies; I² = 0.0%). One study reported an association between improved cognition and depressive symptoms in a cohort of patients with type 2 diabetes mellitus and depression. Two studies investigating metformin versus pioglitazone showed a superior, but not significant, effect of pioglitazone on depressive symptoms (SMD: 1.56; 95%CI: -0.52 to 3.56; p = 0.13;I² = 94.9%; N = 2 studies).

LIMITATIONS

Assessment of risk of bias identified two studies as having "some concerns".

CONCLUSIONS

Our findings suggest that metformin might be re-purposed for the treatment of cognitive deficits in select clinical conditions.

Concomitant medications, functional foods, and supplements: An Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) 2022

Background

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) is intended to provide clinicians an overview of the body weight effects of concomitant medications (i.e., pharmacotherapies not specifically for the treatment of obesity) and functional foods, as well as adverse side effects of supplements sometimes used by patients with pre-obesity/obesity.

Methods

The scientific information for this CPS is based upon published scientific citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership.

Results

This CPS outlines clinically relevant aspects of concomitant medications, functional foods, and many of the more common supplements as they relate to pre-obesity and obesity. Topics include a discussion of medications that may be associated with weight gain or loss, functional foods as they relate to obesity, and side effects of supplements (i.e., with a focus on supplements taken for weight loss). Special attention is given to the warnings and lack of regulation surrounding weight loss supplements.

Conclusions

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) on concomitant medications, functional foods, and supplements is one of a series of OMA CPSs designed to assist clinicians in the care of patients with the disease of pre-obesity/obesity. Implementation of appropriate practices in these areas may improve the health of patients, especially those with adverse fat mass and adiposopathic metabolic consequences.

Metformin: Sex/Gender Differences in Its Uses and Effects—Narrative Review

Metformin (MTF) occupies a major and fundamental position in the therapeutic management of type 2 diabetes mellitus (T2DM). Gender differences in some effects and actions of MTF have been reported. Women are usually prescribed lower MTF doses compared to men and report more gastrointestinal side effects. The incidence of cardiovascular events in women on MTF has been found to be lower to that of men on MTF. Despite some promising results with MTF regarding pregnancy rates in women with PCOS, the management of gestational diabetes, cancer prevention or adjunctive cancer treatment and COVID-19, most robust meta-analyses have yet to confirm such beneficial effects.

The Effects of Combined Therapy With Metformin and Hydroxypropyl-β-Cyclodextrin in a Mouse Model of Niemann-Pick Disease Type C1

Niemann-Pick disease type C1 (NPC1) is a neurodegenerative disorder characterized by lysosomal storage of free cholesterol. 2-Hydroxypropyl-β-cyclodextrin (HPβCD) is a cyclic oligosaccharide derivative that is being developed to treat NPC1. Recently, metformin was reported to be beneficial in various neurodegenerative diseases, such as Alzheimer's and Huntington's diseases. In this study, we examined the effects of combined treatment with HPβCD and metformin on Npc1 ^-/- mice. Unfortunately, body weight and survival rates showed that cotreatment with metformin did not extend survival time and increase the body weight of HPβCD-treated Npc1 ^-/- mice. However, cotreatment with metformin reduced inflammatory response and inhibited the proinflammatory cytokine release in the brain, liver and spleen of HPβCD-treated Npc1 ^-/- mice. Furthermore, metformin did not reduce the free cholesterol levels in Npc1 ^-/- brain tissue or fibroblasts. In conclusion, our results demonstrate that metformin does not show beneficial effects on body weight or survival time but reduced the inflammatory response in a mouse model of NPC1 when combined with HPβCD.

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.

Effect of Propionic Acid on Diabetes-Induced Impairment of Unfolded Protein Response Signaling and Astrocyte/Microglia Crosstalk in Rat Ventromedial Nucleus of the Hypothalamus

Background

The aim was to investigate the influence of propionic acid (PA) on the endoplasmic reticulum (ER), unfolded protein response (UPR) state, and astrocyte/microglia markers in rat ventromedial hypothalamus (VMH) after type 2 diabetes mellitus (T2DM).

Methods

Male Wistar rats were divided: (1) control, (2) T2DM, and groups that received the following (14 days, orally): (3) metformin (60 mg/kg), (4) PA (60 mg/kg), and (5) PA+metformin. Western blotting, RT-PCR, transmission electron microscopy, and immunohistochemical staining were performed.

Results

We found T2DM-associated enlargement of ER cisterns, while drug administration slightly improved VMH ultrastructural signs of damage. GRP78 level was 2.1-fold lower in T2DM vs. control. Metformin restored GRP78 to control, while PA increased it by 2.56-fold and metformin+PA—by 3.28-fold vs. T2DM. PERK was elevated by 3.61-fold in T2DM, after metformin—by 4.98-fold, PA—5.64-fold, and metformin+PA—3.01-fold vs. control. A 2.45-fold increase in ATF6 was observed in T2DM. Metformin decreased ATF6 content vs. T2DM. Interestingly, PA exerted a more pronounced lowering effect on ATF6, while combined treatment restored ATF6 to control. IRE1 increased in T2DM (2.4-fold), metformin (1.99-fold), and PA (1.45-fold) groups vs. control, while metformin+PA fully normalized its content. The Iba1 level was upregulated in T2DM (5.44-fold) and metformin groups (6.88-fold). Despite PA treatment leading to a further 8.9-fold Iba1 elevation, PA+metformin caused the Iba1 decline vs. metformin and PA treatment. GFAP level did not change in T2DM but rose in metformin and PA groups vs. control. PA+metformin administration diminished GFAP vs. PA. T2DM-induced changes were associated with dramatically decreased ZO-1 levels, while PA treatment increased it almost to control values.

Conclusions

T2DM-induced UPR imbalance, activation of microglia, and impairments in cell integrity may trigger VMH dysfunction. Drug administration slightly improved ultrastructural changes in VMH, normalized UPR, and caused an astrocyte activation. PA and metformin exerted beneficial effects for counteracting diabetes-induced ER stress in VMH.

The effect of metformin on body mass index and metabolic parameters in non-diabetic HIV-positive patients: a meta-analysis

We sought to evaluate the effetc of metformin on body mass index (BMI) and metabolic parameters in HIV-positive patients. We performed a comprehensive search through five major indexing databases, using keywords ("metformin" OR "dimethylguanylguanidine" OR "biguanide" OR "Glucophage") AND ("HIV" OR "human immunodeficiency virus" OR "AIDS" OR "Acquired immunodeficiency syndrome"), and all possible combinations until January 15, 2021. We measured standardized mean differences (SMD) and 95% confidence intervals (CI) for each outcome. We finally included 12 RCTs (577 participants, 274 in the metformin group and 303 in the comparators). Metformin did not significantly change BMI index compared to various comparators. Metformin generally improve LDL levels (SMD = 0.29, 95% CI: - 1.00 1.57, P = 0.01), HDL levels (SMD = - 0.15, 95% CI: - 0.72 0.41, P = 0.001), triglycerides values (SMD = 0.46, 95% CI: - 0.36 1.27, P < 0.00001), fasting glucose (SMD = - 0.82, 95% CI: - 1.80 0.15, P < 0.00001), insulin 120 min (SMD = - 0.82, 95% CI: - 1.59-0.04, P = 0.02), and glucose 120 min (SMD = - 1.24, 95% CI: - 2.57 0.10, P < 0.0001), but worsened total cholesterol values (SMD = 1.24, 95% CI: - 0.98 3.46, P = 0.0001). Metformin is safe for weight loss in obese people; however, this drug may not be suitable for everyone, especially those who are not overweight. Nevertheless the body of evidences may suggest that metformin had promising impacts on metabolic parameters in patients with both HIV, it is still unknown that such surrogate changes will translate to long-standing clinical advantages.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-021-00869-1.

Investigation of the Possible Correlation between Idiopathic Parkinson's Disease and Diabetes Mellitus in Egyptian Patients: A Pilot Study

OBJECTIVES

To study the diabetes-Parkinson's disease (PD) linkage.

METHODS

The investigators recorded the rapid eye movement sleep behavior disorder screening questionnaire (RBDSQ) score for 60 diabetic patients: 30 patients were treated with metformin-inclusive sulfonylurea and 30 patients were treated with sulphonylurea(s) monotherapy and matched with 30 controls. We evaluated blood glucose kinetics during a 75 g oral glucose tolerance test for (22) nondiabetic parkinsonian patients and (10) controls. The motor complications scores were recorded for all parkinsonian patients using the relevant parts of the Unified Parkinson's Disease Rating Scale (UPDRS) part IV.

RESULTS

Diabetics recorded higher scores of RBDSQ than controls (p < 0.001), with no differences related to antidiabetic therapy. In nondiabetic PD patients, after oral glucose, blood glucose was significantly higher at T1 (p < 0.001) than controls. Moreover, the total area under the time curve for blood glucose levels was significantly higher in PD compared to controls (281.22 ± 52.25 vs. 245.65 ± 48.63 mg.hr./dL; p=0.013). Higher blood glucose levels were associated with motor abnormalities. Diabetic PD patients recorded higher scores of UPDRS (p < 0.001).

CONCLUSION

Diabetes mellitus and Parkinson's disease are linked, which raises concerns about either of them, probably increasing the risk of the other. This trial is registered with NCT03685357.

Sustained In Vitro and In Vivo Delivery of Metformin from Plant Pollen-Derived Composite Microcapsules

We developed a dual microencapsulation platform for the type 2 diabetes drug metformin (MTF), which is aimed to increase its bioavailability. We report the use of Lycopodium clavatum sporopollenin (LCS), derived from their natural spores, and raw Phoenix dactylifera L. (date palm) pollens (DPP) for MTF microencapsulation. MTF was loaded into LCS and DPP via a vacuum and a novel method of hydration-induced swelling. The loading capacity (LC) and encapsulation efficiency (EE) percentages for MTF-loaded LCS and MTF-loaded DPP microcapsules were 14.9% ± 0.7, 29.8 ± 0.8, and 15.2% ± 0.7, 30.3 ± 1.0, respectively. The release of MTF from MTF-loaded LCS microcapsules was additionally controlled by re-encapsulating the loaded microcapsules into calcium alginate (ALG) microbeads via ionotropic gelation, where the release of MTF was found to be significantly slower and pH-dependent. The pharmacokinetic parameters, obtained from the in vivo study, revealed that the relative bioavailability of the MTF-loaded LCS-ALG beads was 1.215 times higher compared to pure MTF, following oral administration of a single dose equivalent to 25 mg/kg body weight MTF to streptozotocin (STZ)-induced diabetic male Sprague-Dawley rats. Significant hypoglycemic effect was obtained for STZ-induced diabetic rats orally treated with MTF-loaded LCS-ALG beads compared to control diabetic rats. Over a period of 29 days, the STZ-induced diabetic rats treated with MTF-loaded LCS-ALG beads showed a decrease in the aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglycerides, cholesterol, and low-density lipoprotein-cholesterol (LDL-C) levels, as well as an increase in glutathione peroxidase (GPx) and a recovery in the oxidative stress biomarker, lipid peroxidation (LPx). In addition, histopathological studies of liver, pancreas, kidney, and testes suggested that MTF-loaded LCS-ALG beads improved the degenerative changes in organs of diabetic rats. The LCS-ALG platform for dual encapsulation of MTF achieved sustained MTF delivery and enhancement of bioavailability, as well as the improved biochemical and histopathological characteristics in in vivo studies, opening many other intriguing applications in sustained drug delivery.

Incorporation of Sulfonamide Moiety into Biguanide Scaffold Results in Apoptosis Induction and Cell Cycle Arrest in MCF-7 Breast Cancer Cells

Metformin, apart from its glucose-lowering properties, has also been found to demonstrate anti-cancer properties. Anti-cancer efficacy of metformin depends on its uptake in cancer cells, which is mediated by plasma membrane monoamine transporters (PMAT) and organic cation transporters (OCTs). This study presents an analysis of transporter mediated cellular uptake of ten sulfonamide-based derivatives of metformin in two breast cancer cell lines (MCF-7 and MDA-MB-231). Effects of these compounds on cancer cell growth inhibition were also determined. All examined sulfonamide-based analogues of metformin were characterized by greater cellular uptake in both MCF-7 and MDA-MB-231 cells, and stronger cytotoxic properties than those of metformin. Effective intracellular transport of the examined compounds in MCF-7 cells was accompanied by high cytotoxic activity. For instance, compound 2 with meta-methyl group in the benzene ring inhibited MCF-7 growth at micromolar range (IC₅₀ = 87.7 ± 1.18 µmol/L). Further studies showed that cytotoxicity of sulfonamide-based derivatives of metformin partially results from their ability to induce apoptosis in MCF-7 and MDA-MB-231 cells and arrest cell cycle in the G0/G1 phase. In addition, these compounds were found to inhibit cellular migration in wound healing assay. Importantly, the tested biguanides are more effective in MCF-7 cells at relatively lower concentrations than in MDA-MB-231 cells, which proves that the effectiveness of transporter-mediated accumulation in MCF-7 cells is related to biological effects, including MCF-7 cell growth inhibition, apoptosis induction and cell cycle arrest. In summary, this study supports the hypothesis that effective transporter-mediated cellular uptake of a chemical molecule determines its cytotoxic properties. These results warrant a further investigation of biguanides as putative anti-cancer agents.

Novel Sulfonamide-Based Analogs of Metformin Exert Promising Anti-Coagulant Effects without Compromising Glucose-Lowering Activity

Metformin, one of the most frequently prescribed oral anti-diabetic drugs, is characterized by multidirectional activity, including lipid lowering, cardio-protective and anti-inflammatory properties. This study presents synthesis and stability studies of 10 novel sulfonamide-based derivatives of metformin with alkyl substituents in the aromatic ring. The potential of the synthesized compounds as glucose-lowering agents and their effects on selected parameters of plasma and vascular hemostasis were examined. Compounds with two or three methyl groups in the aromatic ring (6, 7, 9, 10) significantly increased glucose uptake in human umbilical vein endothelial cells (HUVECs), e.g., 15.8 µmol/L for comp. 6 at 0.3 µmol/mL versus 11.4 ± 0.7 µmol/L for control. Basic coagulation studies showed that all examined compounds inhibit intrinsic coagulation pathway and the process of fibrin polymerization stronger than the parent drug, metformin, which give evidence of their greater anti-coagulant properties. Importantly, synthesized compounds decrease the activity of factor X, a first member of common coagulation pathway, while metformin does not affect coagulation factor X (FX) activity. A multiparametric clot formation and lysis test (CL-test) revealed that the examined compounds significantly prolong the onset of clot formation; however, they do not affect the overall potential of clot formation and fibrinolysis. Erythrotoxicity studies confirmed that none of the synthesized compounds exert an adverse effect on erythrocyte integrity, do not contribute to the massive hemolysis and do not interact strongly with the erythrocyte membrane. In summary, chemical modification of metformin scaffold into benzenesulfonamides containing alkyl substituents leads to the formation of potential dual-action agents with comparable glucose-lowering properties and stronger anti-coagulant activity than the parent drug, metformin.

Role of metformin in various pathologies: state-of-the-art microcapsules for improving its pharmacokinetics

Metformin was originally derived from a botanical ancestry and became the most prescribed, first-line therapy for Type 2 diabetes in most countries. In the last century, metformin was discovered twice for its antiglycemic properties in addition to its antimalarial and anti-influenza effects. Metformin exhibits flip-flop pharmacokinetics with limited oral bioavailability. This review outlines metformin pharmacokinetics, pharmacodynamics and recent advances in polymeric particulate delivery systems as a potential tool to target metformin delivery to specific tissues/organs. This interesting biguanide is being rediscovered this century for multiple clinical indications as anticancer, anti-aging, anti-inflammatory, anti-Alzheimer's and much more. Microparticulate delivery systems of metformin may improve its oral bioavailability and optimize the therapeutic goals expected.

Metformin Protects From Rotenone-Induced Nigrostriatal Neuronal Death in Adult Mice by Activating AMPK-FOXO3 Signaling and Mitigation of Angiogenesis

Parkinson’s disease (PD) is a neurodegenerative disease that affects substantia nigra dopamine neurons. Many studies have documented the role of oxidative stress and angiogenesis in the pathogenesis of PD. Metformin (MTF) is an antidiabetic medication and AMP-activated protein kinase (AMPK) regulator that has shown antioxidant and antiangiogenic properties in many disorders. The aim of this study is to investigate the neuroprotective effect of MTF in a mouse model of rotenone-prompted PD with a highlight on its influence on the AMPK/forkhead box transcription factor O3 (FOXO3) pathway and striatal angiogenesis. In the running study, PD was induced in mice using repeated doses of rotenone and concomitantly treated with MTF 100 or 200 mg/kg/day for 18 days. Rotarod and pole tests were used to examine the animals’ motor functionality. After that, animals were sacrificed, and brains were isolated and processed for immunohistochemical investigations or biochemical analyses. Oxidant stress and angiogenic markers were measured, including reduced glutathione, malondialdehyde, the nuclear factor erythroid 2–related factor 2 (Nrf2), hemoxygenase-1, thioredoxin, AMPK, FOXO3, and vascular endothelial growth factor (VEGF). Results indicated that MTF improved animals’ motor function, improved striatal glutathione, Nrf2, hemoxygenase-1, and thioredoxin. Furthermore, MTF upregulated AMPK-FOXO3 proteins and reduced VEGF and cleaved caspase 3. MTF also increased the number of tyrosine hydroxylase (TH)–stained neurons in the substantia nigra neurons and in striatal neuronal terminals. This study is the first to highlight that the neuroprotective role of MTF is mediated through activation of AMPK-FOXO3 signaling and inhibition of the proangiogenic factor, VEGF. Further studies are warranted to confirm this mechanism in other models of PD and neurodegenerative diseases.

Effective Cellular Transport of Ortho-Halogenated Sulfonamide Derivatives of Metformin Is Related to Improved Antiproliferative Activity and Apoptosis Induction in MCF-7 Cells

Metformin is a substrate for plasma membrane monoamine transporters (PMAT) and organic cation transporters (OCTs); therefore, the expression of these transporters and interactions between them may affect the uptake of metformin into tumor cells and its anticancer efficacy. The aim of this study was to evaluate how chemical modification of metformin scaffold into benzene sulfonamides with halogen substituents (compounds 1-9) may affect affinity towards OCTs, cellular uptake in two breast cancer cell lines (MCF-7 and MDA-MB-231) and antiproliferative efficacy of metformin. The uptake of most sulfonamides was more efficient in MCF-7 cells than in MDA-MB-231 cells. The presence of a chlorine atom in the aromatic ring contributed to the highest uptake in MCF-7 cells. For instance, the uptake of compound 1 with o-chloro substituent in MCF-7 cells was 1.79 ± 0.79 nmol/min/mg protein, while in MDA-MB-231 cells, the uptake was considerably lower (0.005 ± 0.0005 nmol/min/mg protein). The elevated uptake of tested compounds in MCF-7 was accompanied by high antiproliferative activity, with compound 1 being the most active (IC50 = 12.6 ± 1.2 µmol/L). Further studies showed that inhibition of MCF-7 growth is associated with the induction of early and late apoptosis and cell cycle arrest at the G0/G1 phase. In summary, the chemical modification of the biguanide backbone into halogenated sulfonamides leads to improved transporter-mediated cellular uptake in MCF-7 and contributes to the greater antiproliferative potency of studied compounds through apoptosis induction and cell cycle arrest.

Metformin and trimetazidine ameliorate diabetes-induced cognitive impediment in status epileptic rats

Patients with diabetes and epilepsy are more prone to cognitive impairment, dementia, and even Alzheimer's disease. Diabetes-induced inflammatory process is one of the main contributing factors; however, the impact on seizure is not clear. The current study is aimed to examine the role of metformin and trimetazidine in the reduction of neuronal damage caused by inflammatory mediators and apoptotic factors in diabetic epileptic rodent model. Diabetic epileptic rats received orally either metformin (100 mg/kg) or trimetazidine (10 mg/kg) for 3 weeks exhibited reduced cognitive function and ameliorated the disturbed brain neurotransmission. Besides, they improved both the inflammatory status and the histopathologic alterations. Administration of metformin or trimetazidine ameliorated the deterioration in cognitive function in Morris water maze (MWM) and reduced seizure score. Furthermore, brain neurotransmitters glutamate and γ-aminobutyric acid (GABA) were reverted back to their normal values. Both treatments reduced the rise in inflammatory cytokines interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), apoptotic markers nuclear factor-κB (NF-κB) and caspase-3, and improved the pathological photomicrograph of the hippocampus of diabetic epileptic rats. Such effects were closely correlated to the observed increase in the adenosine triphosphate and adenosine diphosphate (ATP/ADP) ratio and reduction of death-associated protein (DAP) and mammalian target of rapamycin (mTOR). In conclusion, the current study shed light on the potential neuroprotective role of metformin and trimetazidine in the amelioration of cognitive function via hindering inflammatory processes in diabetic epileptic rats.

An investigation into the pleiotropic activity of metformin. A glimpse of haemostasis

The most characteristic features of type 2 diabetes mellitus (T2DM) are hyperglycaemia and insulin resistance, however, patients with T2DM are at higher risk of cardiovascular disease (CVD) and atherosclerosis. Diabetes, frequently related to metabolic and vascular impairments, is also associated with thrombosis, increased blood coagulation and an imbalance between coagulation and fibrinolysis. Metformin is the most often used oral glucose-lowering agent; its beneficial properties include lowering insulin resistance, weight reduction and cardioprotection. Available data suggest that the advantageous properties of metformin stem from its favourable effects on endothelium, and anti-oxidative and anti-inflammatory properties. This paper reviews the favourable impact of metformin on endothelial function, with particular emphasis on the release of endogenous molecules modulating the state of the vascular endothelium and coagulation. It also summarizes the present knowledge on the influence of metformin on platelet activity and plasma haemostasis, including clot formation, stabilization and fibrinolysis. Its findings confirm that metformin should constitute first line therapy of T2DM subjects; however, more comprehensive methodical studies are required to discover the full potential of this drug.

Pleiotropic Activity of Metformin and Its Sulfonamide Derivatives on Vascular and Platelet Haemostasis

As type 2 diabetes mellitus (T2DM) predisposes patients to endothelial cell injury and dysfunction, improvement of vascular function should be an important target for therapy. The aim of this study was to evaluate the effects of metformin, its sulfenamide and sulfonamide derivatives on selected parameters of endothelial and smooth muscle cell function, and platelet activity. Metformin was not found to significantly affect the viability of human umbilical vein endothelial cells (HUVECs) or aortal smooth muscle cells (AoSMC); however, it decreased cell migration by approximately 21.8% in wound healing assays after 24 h stimulation (wound closure 32.5 µm versus 41.5 µm for control). Metformin reduced platelet aggregation manifested by 19.0% decrease in maximum of aggregation (Amax), and 20% reduction in initial platelet aggregation velocity (v0). Furthermore, metformin decreased spontaneous platelet adhesion by 27.7% and ADP-induced adhesion to fibrinogen by 29.6% in comparison to control. Metformin sulfenamide with an n-butyl alkyl chain (compound 1) appeared to exert the most unfavourable effects on AoSMC cell viability (IC50 = 0.902 ± 0.015 μmol/mL), while 4-nitrobenzenesulfonamide (compound 3) and 2-nitrobenzenesulfonamide (compound 4) derivatives of metformin did not affect AoSMC and HUVEC viability at concentrations up to 2.0 μmol/mL. These compounds were also found to significantly reduce migration of smooth muscle cells by approximately 81.0%. Furthermore, sulfonamides 3 and 4 decreased the initial velocity of platelet aggregation by 11.8% and 20.6%, respectively, and ADP-induced platelet adhesion to fibrinogen by 76.3% and 65.6%. Metformin and its p- and o-nitro-benzenesulfonamide derivatives 3, 4 appear to exert beneficial effects on some parameters of vascular and platelet haemostasis.

Effects of berberine and metformin on intestinal inflammation and gut microbiome composition in db/db mice

Berberine and metformin, both established pharmaceutical agents with herbal origins, have incidental beneficial effects on multiple diseases, including diabetes. These effects have been speculated to occur via the gut microbiome. In this study, we administered either berberine or metformin to db/db mice and investigated changes in body weight, food intake, and blood glucose levels. Fresh stool samples were analyzed using 16 s rDNA high-throughput sequencing to evaluate the gut microbiome. Short-chain fatty acids (SCFA) in the stool were quantified using gas chromatography. The expression of NF-κB signaling pathway and tight junction (ZO1 and occludin) proteins in the intestinal epithelium was determined using qPCR and western blotting. The intestinal barrier structure was examined using transmission electron microscopy and serum lipopolysaccharide (LPS) was measured using a commercial kit. Both berberine and metformin reduced food intake, body weight, and blood glucose and HbA1c levels. Both treatments effectively restored the intestinal SCFA content, reduced the level of serum LPS, relieved intestinal inflammation, and repaired intestinal barrier structure. Intervention with metformin or berberine modified the gut microbiome in db/db mice, increasing the number of SCFA-producing bacteria (e.g., Butyricimonas, Coprococcus, Ruminococcus) and reducing opportunistic pathogens (e.g., Prevotella, Proteus). An increased abundance of other probiotics including Lactobacillus and Akkermansia was also observed. Berberine and metformin can modulate the composition of the gut microbiome and reduce body weight, blood glucose levels, and intestinal inflammation in db/db mice, which demonstrates their effectiveness in the reduction of diabetic complications in this model.

Dose-response associations between metabolic indexes and the risk of comorbid type 2 diabetes mellitus among rheumatoid arthritis patients from Northern China: a case-control study

OBJECTIVE

To investigate whether there were any differences in the patterns of metabolic abnormalities between patients with rheumatoid arthritis (RA) with comorbid type 2 diabetes mellitus (T2DM) and other populations, and to plot the dose-response relationships between metabolic indexes and the risk of comorbid T2DM among patients with RA.

DESIGN AND SETTING

This is a retrospective case-control study using electronic medical records (EMRs). Patients with RA and/or T2DM or controls who were admitted to the First Affiliated Hospital of China Medical University between April 2008 and December 2016 were retrospectively recruited through the EMR system. After age-matching and sex-matching, 261 controls, 274 patients with T2DM, 276 patients with RA and 151 patients with RA+T2DM were eventually recruited.

RESULTS

Patients with RA+T2DM exhibited higher levels of systolic blood pressure (SBP), fasting plasma glucose (FPG) and triglyceride (TG) than the RA only patients. Moreover, the proportions of impaired fasting glucose (IFG), and total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) dyslipidaemia in the RA+T2DM group were higher than those in the RA alone group (for IFG: 28.48% vs 18.84%, p=0.02; for TC: 25.17% vs 15.22%, p=0.01; for LDL-C: 25.83% vs 17.03%; p=0.03). Rheumatoid factor (RF) positivity and IFG were independent risk indicators for comorbid T2DM among patients with RA (for RF positivity: OR=0.45; 95% CI: 0.29 to 0.69; p<0.001; for IFG: OR=1.70; 95% CI: 1.04 to 2.76; p=0.03).

CONCLUSION

Linear dose-response associations between SBP, TC, TG and the risk of comorbid T2DM among patients with RA were observed, whereas a non-linear dose-response association between FPG and the risk of comorbid T2DM was found. Patients with RA+T2DM were more likely to exhibit metabolic abnormalities than RA only patients. Patients with RA+T2DM with metabolic abnormalities deserve more attention from rheumatologists and endocrinologists.

Metformin reduces insulin resistance and the tendency toward hyperglycaemia and dyslipidaemia in dogs with hyperadrenocorticism

Hypercortisolism induces a state of insulin resistance that can occur concurrently with fasting hyperglycaemia, dyslipidaemia and diabetes mellitus. Metformin reduces hepatic glucose production and insulin resistance of the skeletal muscle and adipose tissue. The aim of this study was to evaluate the effects of metformin on the control of metabolic disorders of dogs with hyperadrenocorticism (HAC). Twenty-three dogs with HAC were randomly divided into two groups, consisting of a control group and a metformin group (10 mg metformin/kg/12 h). Both groups received the same treatment for HAC. At baseline and 3 months, blood glucose, total cholesterol, triglycerides and insulin concentrations, in addition to urinary cortisol:creatinine ratio, Homeostatic Model Assessment (HOMA) for insulin sensitivity and β-cell function were measured. Dogs treated with metformin showed significantly reduced glycaemia, cholesterolaemia and triglyceridaemia. They also presented reduced hyperinsulinism and insulin resistance, as well as improved pancreatic β-cell function. The implementation of metformin as an adjuvant therapy is effective for the normalisation of metabolic disorders of dogs with HAC.

Age Dependent Effects of Metformin in Wistar Albino Male Rats with Metabolic Syndrome

Background and aims: Comparative estimation of metformin treatment effectiveness in adult and young rats with metabolic syndrome (MS).

Materials and methods: A metabolic syndrome model was induced by full replacement of drinking water with 20% fructose solution in Wistar albino male rats of two age categories (young animals of 21 days age (50-70g) and adults (160-180g)). After 60 days of MS modelling and metformin treatment, hematological, biochemical, blood pressure, chromatin DNA fragmentation investigations, as well as morphological macroscopic and microscopic studies were carried out.

Results: In young rats, effects of metformin on blood clotting time, lipid metabolism and DNA fragmentation were more pronounced. Mature rats showed greater susceptibility to this drug as for influence on pancreas and visceral fat relative weights.

Conclusions: In our experiment with young and adult rats with MS and metformin treatment we showed that this preparation effect was age-dependent for lipid metabolism indices, blood clotting time, nuclear DNA fragmentation parameters, as well as for changes of relative organs weights and target organs morphological structure. Metformin treatment allowed a partial normalization of serum levels of lowdensity lipoproteins (LDLP) and ratio high lowdensity lipoproteins / lowdensity lipoproteins (HDLP/LDLP), hemoglobin contents, hematocrit percentage, DNA fragmentation rates, with simultaneous worsening in blood clotting time, blood pressure levels, liver and pancreas relative organs weights (of young rats).

Metformin - a Future Therapy for Neurodegenerative Diseases : Theme: Drug Discovery, Development and Delivery in Alzheimer's Disease Guest Editor: Davide Brambilla

Type 2 diabetes mellitus (T2DM) is a complex, chronic and progressive metabolic disease, which is characterized by relative insulin deficiency, insulin resistance, and high glucose levels in blood. Esteemed published articles and epidemiological data exhibit an increased risk of developing Alzheimer's disease (AD) in diabetic pateints. Metformin is the most frequently used oral anti-diabetic drug, which apart from hypoglycaemic activity, improves serum lipid profiles, positively influences the process of haemostasis, and possesses anti-inflammatory properties. Recently, scientists have put their efforts in establishing metformin's role in the treatment of neurodegenerative diseases, such as AD, amnestic mild cognitive impairment and Parkinson's disease. Results of several clinical studies confirm that long term use of metformin in diabetic patients contributes to better cognitive function, compared to participants using other anti-diabetic drugs. The exact mechanism of metformin's advantageous activity in AD is not fully understood, but scientists claim that activation of AMPK-dependent pathways in human neural stem cells might be responsible for the neuroprotective activity of metformin. Metformin was also found to markedly decease Beta-secretase 1 (BACE1) protein expression and activity in cell culture models and in vivo, thereby reducing BACE1 cleavage products and the production of Aβ (β-amyloid). Furthermore, there is also some evidence that metformin decreases the activity of acetylcholinesterase (AChE), which is responsible for the degradation of acetylcholine (Ach), a neurotransmitter involved in the process of learning and memory. In regard to the beneficial effects of metformin, its anti-inflammatory and anti-oxidative properties cannot be omitted. Numerous in vitro and in vivo studies have confirmed that metformin ameliorates oxidative damage.

Developing a metformin prescribing tool for use in adults with mental illness to reduce medication-related weight gain and cardiovascular risk

OBJECTIVES

There is considerable evidence that metformin reduces weight gain associated with antipsychotic medication. The aim of this study was to develop an easy-to-use metformin prescribing tool in order to enable clinicians to prescribe metformin safely and confidently.

METHODS

The authors undertook a survey of clinicians and reviewed the published literature and existing guidelines concerning the use of metformin to reduce weight gain in adults with mental illness.

RESULTS

A metformin prescribing tool was devised based on the literature, national cardiovascular and diabetes guidelines and Australian metformin prescribing recommendations. The metformin prescribing tool guides clinicians through the considerations required for appropriate selection of the target patient population and safe prescription of metformin.

CONCLUSIONS

A novel, easy-to-use, one-page reference has been developed for busy clinicians that can be laminated and displayed in consulting rooms and psychiatric inpatient units to address weight gain and obesity associated with antipsychotic medications in people with mental illness.

AMP-activated protein kinase: a therapeutic target in intestinal diseases

Adenosine monophosphate (AMP)-activated protein kinase (AMPK), a highly conserved energy sensor, has a crucial role in cardiovascular, neurodegenerative and inflammatory diseases, as well as in cancer and metabolic disorders. Accumulating studies have demonstrated that AMPK activation enhances paracellular junctions, nutrient transporters, autophagy and apoptosis, and suppresses inflammation and carcinogenesis in the intestine, indicating an essential role of AMPK in intestinal health. AMPK inactivation is an aetiological factor in intestinal dysfunctions. This review summarizes the favourable outcomes of AMPK activation on intestinal health, and discusses AMPK as a potential therapeutic target for intestinal diseases.

Metformin and Its Sulfenamide Prodrugs Inhibit Human Cholinesterase Activity

The results of epidemiological and pathophysiological studies suggest that type 2 diabetes mellitus (T2DM) may predispose to Alzheimer's disease (AD). The two conditions present similar glucose levels, insulin resistance, and biochemical etiologies such as inflammation and oxidative stress. The diabetic state also contributes to increased acetylcholinesterase (AChE) activity, which is one of the factors leading to neurodegeneration in AD. The aim of this study was to assess in vitro the effects of metformin, phenformin, and metformin sulfenamide prodrugs on the activity of human AChE and butyrylcholinesterase (BuChE) and establish the type of inhibition. Metformin inhibited 50% of the AChE activity at micromolar concentrations (2.35 μmol/mL, mixed type of inhibition) and seemed to be selective towards AChE since it presented low anti-BuChE activity. The tested metformin prodrugs inhibited cholinesterases (ChE) at nanomolar range and thus were more active than metformin or phenformin. The cyclohexyl sulfenamide prodrug demonstrated the highest activity towards both AChE (IC₅₀ = 890 nmol/mL, noncompetitive inhibition) and BuChE (IC₅₀ = 28 nmol/mL, mixed type inhibition), while the octyl sulfenamide prodrug did not present anti-AChE activity, but exhibited mixed inhibition towards BuChE (IC₅₀ = 184 nmol/mL). Therefore, these two bulkier prodrugs were concluded to be the most selective compounds for BuChE over AChE. In conclusion, it was demonstrated that biguanides present a novel class of inhibitors for AChE and BuChE and encourages further studies of these compounds for developing both selective and nonselective inhibitors of ChEs in the future.

Discovery of Novel Insulin Sensitizers: Promising Approaches and Targets

Insulin resistance is the undisputed root cause of type 2 diabetes mellitus (T2DM). There is currently an unmet demand for safe and effective insulin sensitizers, owing to the restricted prescription or removal from market of certain approved insulin sensitizers, such as thiazolidinediones (TZDs), because of safety concerns. Effective insulin sensitizers without TZD-like side effects will therefore be invaluable to diabetic patients. The specific focus on peroxisome proliferator-activated receptor γ- (PPARγ-) based agents in the past decades may have impeded the search for novel and safer insulin sensitizers. This review discusses possible directions and promising strategies for future research and development of novel insulin sensitizers and describes the potential targets of these agents. Direct PPARγ agonists, selective PPARγ modulators (sPPARγMs), PPARγ-sparing compounds (including ligands of the mitochondrial target of TZDs), agents that target the downstream effectors of PPARγ, along with agents, such as heat shock protein (HSP) inducers, 5'-adenosine monophosphate-activated protein kinase (AMPK) activators, 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) selective inhibitors, biguanides, and chloroquines, which may be safer than traditional TZDs, have been described. This minireview thus aims to provide fresh perspectives for the development of a new generation of safe insulin sensitizers.

Metformin-like antidiabetic, cardio-protective and non-glycemic effects of naringenin: Molecular and pharmacological insights

Metformin is a widely used drug for the treatment of type 2 diabetes (T2D). Its blood glucose-lowering effects are initially due to inhibition of hepatic glucose production and increased peripheral glucose utilization. Metformin has also been shown to have several beneficial effects on cardiovascular risk factors and it is the only oral antihyperglycaemic agent thus far associated with decreased macrovascular complications in patients with diabetes. Adenosine Monophosphate Activated-Protein Kinase (AMPK) is a major cellular regulator of lipid and glucose metabolism. Recent evidence shows that pharmacological activation of AMPK improves blood glucose homeostasis, lipid profiles, blood pressure and insulin-resistance making it a novel therapeutic target in the treatment of T2D. Naringenin a flavonoid found in high concentrations as its glycone naringin in citrus fruits, has been reported to have antioxidant, antiatherogenic, anti- dyslipidemic and anti-diabetic effects. It has been shown that naringenin exerts its anti-diabetic effects by inhibition of gluconeogenesis through upregulations of AMPK hence metformin-like effects. Naringin has further been shown to have non-glycemic affects like metformin that mitigate inflammation and cell proliferation. This review evaluates the potential of naringenin as anti-diabetic, anti-dyslipidemic anti-inflammatory and antineoplastic agent similar to metformin and proposes its further development for therapeutic use in clinical practice.

Metformin Induces Growth Inhibition and Cell Cycle Arrest by Upregulating MicroRNA34a in Renal Cancer Cells

BACKGROUND Metformin is a widely used biguanide drug for the treatment of type 2 diabetes. It has been revaluated as a potential anti-cancer drug with promising activity in various tumors. However, the precise mechanisms underlying the suppression of cancer cells by metformin remain not well understood. MATERIAL AND METHODS In this study, human renal cell carcinoma cell line ACHN was used to investigate the anti-proliferation effect of metformin. A cell counting kit-8 assay was used to detect the cell viability. The cell cycle distribution and apoptosis were analyzed by flow cytometry. The expression of cyclin D1 and p27KIP1 was detected by Western blot. The underlying mechanism involving miRNA34a was further investigated by quantitative RT-PCR and transfection with miRNA inhibitor specific for miRNA34a in ACHN, 769-P, and A498 cells. RESULTS Metformin could significantly inhibit the proliferation of ACHN cells in a dose- and time-dependent manner. In addition, the results showed that metformin induced G0/G1 phase arrest and delayed entry into S phase in ACHN cells. It was shown that metformin downregulates the expression of cyclin D1 and increases the p27KIP1 level. Furthermore, metformin increased ACHN cell death. Lastly, miRNA34a was found to be upregulated by metformin in ACHN, 769-P, and A498 cells. Subsequently, it was demonstrated that inhibition of miRNA34a could partially attenuate the suppressive effect of metformin on renal cancer cell proliferation. CONCLUSIONS The study data revealed that metformin induced cell growth inhibition and cell cycle arrest partially by upregulating miRNA34a in renal cancer cells.

Potential Benefit of Metformin as Treatment for Colon Cancer: the Evidence so Far

Metformin is known as a hypoglycaemic agent that regulates glucose homeostasis by inhibiting liver glucose production and increasing muscle glucose uptake. Colorectal cancer (CRC) is one of the most common cancers worldwide, with about a million new cases diagnosed each year. The risk factors for CRC include advanced age, smoking, black race, obesity, low fibre diet, insulin resistance, and the metabolic syndrome. We have searched Medline for the metabolic syndrome and its relation to CRC, and metformin as a potential treatment of colorectal cancer. Administration of metformin alone or in combination with chemotherapy has been shown to suppress CRC. The mechanism that explains how insulin resistance is associated with CRC is complex and not fully understood. In this review we have summarised studies which showed an association with the metabolic syndrome as well as studies which tackled metformin as a potential treatment of CRC. In addition, we have also provided a summary of how metformin at the cellular level can induce changes that suppress the activity of cancer cells.

Serotonin transporter gene (5-HTT) polymorphism and major depressive disorder in patients in Bogotá, Colombia

<p><strong>Introducción.</strong> El polimorfismo 5-HTT se ha asociado con el trastorno de depresión mayor, aunque el planteamiento ha generado controversia.<br /><strong>Objetivo.</strong> Determinar la asociación del polimorfismo 5-HTT con la depresión mayor en Bogotá, Colombia.<br /><strong>Materiales y métodos.</strong> Se hizo un estudio de casos y controles pareado por sexo y edad (±5 años), con una razón de uno a uno (68:68). El trastorno de depresión mayor se diagnosticó con el cuestionario Mini-International Neuropsychiatric Interview, y, el polimorfismo 5-HTT, mediante reacción en cadena de la polimerasa (PCR).<br /><strong>Resultados.</strong> Las mujeres predominaron entre los participantes (82,4 %). El alelo corto (short, S) predominó en los casos comparados con los controles (S: 72,1 % Vs. 63,2; L (long): 27,9 % Vs. 36,8 %), y el genotipo SL fue más frecuente en los casos (SL: 45,6 % Vs. 36,8 %; LL: 27,9 % Vs. 36,8 %; SS: 26,5 % Vs. 26,5 %), aunque no significativamente. Hubo diferencias significativas en menores de 37 años, con predominio del alelo S en los casos (p=0,0384; odds ratio - OR=2,75; IC95%: 0,88-8,64). El análisis multivariado ajustado por trastornos concomitantes de ansiedad mostró una asociación significativa de la depresión mayor con el genotipo SL (p=0,049; OR=3,20; IC95% 1,003-10,233); el alelo S estuvo cerca de la significación estadística (p=0,063; OR=2,94; IC95% 0,94-9,13), y fue estadísticamente significativo en los casos de menores de 37 años (p=0,026; OR=10,79; IC95% 1,32-80,36).<br /><strong>Conclusiones.</strong> El genotipo SL se asoció con el trastorno de depresión mayor en pacientes de todas las edades. El alelo S se asoció significativamente con el trastorno de depresión mayor en pacientes menores de 37 años al ajustar por trastornos concomitantes de ansiedad.</p>

Neutrophil Extracellular Trap Mitochondrial DNA and Its Autoantibody in Systemic Lupus Erythematosus and a Proof-of-Concept Trial of Metformin

OBJECTIVE

Neutrophil extracellular traps (NETs) have been shown to play an important role in systemic lupus erythematosus (SLE) pathogenesis by activating plasmacytoid dendritic cells (PDCs) and the type I interferon (IFN) pathway. NETs composed of self-DNA are considered to be of nuclear origin and are a major source of anti-DNA autoantibody generation. This study was undertaken to evaluate whether mitochondrial DNA (mtDNA) resides in NETs, to evaluate whether mtDNA and anti-mtDNA antibodies cause dysregulation of the PDC-IFNα pathway, and to investigate the clinical implication in SLE.

METHODS

Patients with SLE (n = 102), patients with rheumatoid arthritis (n = 30), and healthy donors (n = 40) were enrolled in in vitro studies. NETs were generated from phorbol 12-myristate 13-acetate (PMA)-stimulated peripheral neutrophils. Immunofluorescence staining was used to detect NET formation ex vivo and in lupus nephritis renal biopsy samples. The mtDNA levels and type I IFN-inducible gene scores were measured by quantitative polymerase chain reaction. Anti-mtDNA antibodies, anti-double-stranded DNA (anti-dsDNA) antibodies, and IFNα were detected by enzyme-linked immunosorbent assay. Purified PDCs were stimulated by isolated NETs, mtDNA, or dsDNA, combined with anti-mtDNA or dsDNA IgG, or other culture conditions. Additional patients with SLE (n = 113) were enrolled in a proof-of-concept trial. We evaluated the efficacy and safety of metformin on a background of corticosteroids and conventional immunosuppressive agents in patients with mild or moderate lupus. The primary end point was the efficacy of metformin for reducing disease flare.

RESULTS

We detected mtDNA in NETs, and anti-mtDNA antibody levels were elevated in SLE patients compared with controls and significantly correlated with IFN scores and the disease activity index. The presence of anti-mtDNA antibodies was disproportionately associated with lupus nephritis, and correlated better than anti-dsDNA antibody levels with the lupus nephritis activity index. Mitochondrial DNA was deposited in NETs in lupus nephritis renal biopsy specimens. In addition, mtDNA/anti-mtDNA were greater inducers of PDC IFNα production via Toll-like receptor engagement than dsDNA/anti-dsDNA. We assessed the effect of metformin on down-regulating the NET mtDNA-PDC-IFNα pathway. Metformin decreased PMA-induced NET formation and CpG-stimulated PDC IFNα generation. A proof-of-concept trial of metformin add-on treatment of mild or moderate SLE resulted in decreases in clinical flares, prednisone exposure, and body weight.

CONCLUSION

Our findings establish a link between mtDNA in NETs, anti-mtDNA antibodies, and PDC IFNα pathogenesis in SLE, and highlight that specific strategies to down-regulate this pathway, such as treatment with metformin, may be new approaches to treat SLE.

Metformin: A Hopeful Promise in Aging Research

Even though the inevitable process of aging by itself cannot be considered a disease, it is directly linked to life span and is the driving force behind all age-related diseases. It is an undisputable fact that age-associated diseases are among the leading causes of death in the world, primarily in industrialized countries. During the last several years, an intensive search of antiaging treatments has led to the discovery of a variety of drugs that promote health span and/or life extension. The biguanide compound metformin is widely used for treating people with type 2 diabetes and appears to show protection against cancer, inflammation, and age-related pathologies. Here, we summarize the recent developments about metformin use in translational aging research and discuss its role as a potential geroprotector.

Metformin treatment improves weight and dyslipidemia in children with metabolic syndrome

BACKGROUND

To determine the effects of metformin therapy in children with metabolic syndrome (MS).

METHODS

A retrospective electronic chart review in children aged 8-18 years, from 2000 to 2012 with a diagnosis code for MS (ICD 277.7) that met the modified NCEP ATPIII criteria for MS.

RESULTS

There were a total of 217 subjects, 150 in the non-metformin [untreated group (UTG)] and 67 in the metformin treated group (MTG). At baseline, the MTG had a body mass index (BMI) similar to UTG, but had higher total cholesterol, low-density lipoprotein cholesterol (LDL-C), and non-high density lipoprotein cholesterol (non-HDL-C). At the end of 1 year, the MTG (n=28) had reduced weight percentile (99.4±0.7 vs. 98.9±1.7, p=0.03), BMI percentile (99.2±0.5 vs. 98.8±1.1, p=0.012), total cholesterol (194.9±45.8 vs. 177.9±32.5 mg/dL, p=0.04), LDL-C (128.3±44.7 vs. 113.8±36.0 mg/dL, p=0.04), and non-HDL-C (154.6±45.5 vs. 136.4±35.2 mg/dL, p=0.03) compared to their baseline. The UTG (n=56) did not have any significant change in those parameters.

CONCLUSIONS

Metformin treatment results in significant improvement in BMI, total cholesterol, LDL-C, and non-HDL-C in children with MS.

Pharmacokinetic interactions between topiramate and pioglitazone and metformin

OBJECTIVE

To investigate potential drug-drug interactions between topiramate and metformin and pioglitazone at steady state.

METHODS

Two open-label studies were performed in healthy adult men and women. In Study 1, eligible participants were given metformin alone for 3 days (500 mg twice daily [BID]) followed by concomitant metformin and topiramate (titrated to 100mg BID) from days 4 to 10. In Study 2, eligible participants were randomly assigned to treatment with pioglitazone 30 mg once daily (QD) alone for 8 days followed by concomitant pioglitazone and topiramate (titrated to 96 mg BID) from days 9 to 22 (Group 1) or to topiramate (titrated to 96 mg BID) alone for 11 days followed by concomitant pioglitazone 30 mg QD and topiramate 96 mg BID from days 12 to 22 (Group 2). An analysis of variance was used to evaluate differences in pharmacokinetics with and without concomitant treatment; 90% confidence intervals (CI) for the ratio of the geometric least squares mean (LSM) estimates for maximum plasma concentration (Cmax), area under concentration-time curve for dosing interval (AUC12 or AUC24), and oral clearance (CL/F) with and without concomitant treatment were used to assess a drug interaction.

RESULTS

A comparison to historical data suggested a modest increase in topiramate oral clearance when given concomitantly with metformin. Coadministration with topiramate reduced metformin oral clearance at steady state, resulting in a modest increase in systemic metformin exposure. Geometric LSM ratios and 90% CI for metformin CL/F and AUC12 were 80% (75%, 85%) and 125% (117%, 134%), respectively. Pioglitazone had no effect on topiramate pharmacokinetics at steady state. Concomitant topiramate resulted in decreased systemic exposure to pioglitazone and its active metabolites, with geometric LSM ratios and 90% CI for AUC24 of 85.0% (75.7%, 95.6%) for pioglitazone, 40.5% (36.8%, 44.6%) for M-III, and 83.8% (76.1%, 91.2%) for M-IV, respectively. This effect appeared more pronounced in women than in men. Coadministration of topiramate with metformin or pioglitazone was generally well tolerated by healthy participants in these studies.

CONCLUSIONS

A modest increase in metformin exposure and decrease in topiramate exposure was observed at steady state following coadministration of metformin 500 mg BID and topiramate 100mg BID. The clinical significance of the observed interaction is unclear but is not likely to require a dose adjustment of either agent. Pioglitazone 30 mg QD did not affect the pharmacokinetics of topiramate at steady state, while coadministration of topiramate 96 mg BID with pioglitazone decreased steady-state systemic exposure to pioglitazone, M-III, and M-IV. While the clinical consequence of this interaction is unknown, careful attention should be given to the routine monitoring for adequate glycemic control of patients receiving this concomitant therapy. Concomitant administration of topiramate with metformin or pioglitazone was generally well tolerated and no new safety concerns were observed.

The effect of metformin on the hypothalamic-pituitary-thyroid axis in women with polycystic ovary syndrome and subclinical hypothyroidism

The effect of metformin treatment on the hypothalamic-pituitary-thyroid axis is relatively weakly understood. This study included 24 prediabetic patients with polycystic ovary syndrome and untreated subclinical hypothyroidism, 12 of whom had already been treated with bromocriptine (5.0-7.5 mg daily). The included patients received metformin (2.55 g daily) for 6 months. Glucose homeostasis markers, serum prolactin, and thyroid function tests were determined before, after 3 months, and at the end of the treatment. Beyond improving glucose homeostasis, metformin administered for 6 months reduced serum levels of thyrotropin but did not affect serum levels of total and free thyroid hormones. Thyrotropin-lowering effect of this agent was stronger in patients not treated with bromocriptine than in patients receiving this drug, and weakly correlated with an improvement in insulin sensitivity. The obtained results indicate that metformin treatment may have an impact on thyrotrope function in hypothyroid patients, probably by enhancing the effect of thyroid hormone action in the pituitary.

Gut microbiota-generated metabolites in animal health and disease

Gut microbiota is found in virtually any metazoan, from invertebrates to vertebrates. It has long been believed that gut microbiota, more specifically, the activity of the microbiome and its metabolic products, directly influence a variety of aspects in metazoan physiology. However, the exact molecular relationship among microbe-derived gut metabolites, host signaling pathways, and host physiology remains to be elucidated. Here we review recent discoveries regarding the molecular links between gut metabolites and host physiology in different invertebrate and vertebrate animal models. We describe the different roles of gut microbiome activity and their metabolites in regulating distinct host physiology and the molecular mechanisms by which gut metabolites cause physiological homeostasis via regulating specific host signaling pathways. Future studies in this direction using different animal models will provide the key concepts to understanding the evolutionarily conserved chemical dialogues between gut microbiota and metazoan cells and also human diseases associated with gut microbiota and metabolites.

CGRRF1 as a novel biomarker of tissue response to metformin in the context of obesity

OBJECTIVE

Obesity-associated hyperestrogenism and hyperinsulinemia contribute significantly to the pathogenesis of endometrial cancer. We recently demonstrated that metformin, a drug long used for treatment of type 2 diabetes, attenuates both insulin- and estrogen-mediated proliferative signaling in the obese rat endometrium. In this study, we sought to identify tissue biomarkers that may prove clinically useful to predict tissue response for both prevention and therapeutic studies. We identified CGRRF1 (cell growth regulator with ring finger domain 1) as a novel metformin-responsive gene and characterized its possible role in endometrial cancer prevention.

METHODS

CGRRF1 mRNA expression was evaluated by RT-qPCR in the endometrium of obese and lean rats, and also in normal and malignant human endometrium. CGRRF1 levels were genetically manipulated in endometrial cancer cells, and its effects on proliferation and apoptosis were evaluated by MTT and Western blot.

RESULTS

CGRRF1 is significantly induced by metformin treatment in the obese rat endometrium. In vitro studies demonstrate that overexpression of CGRRF1 inhibits endometrial cancer cell proliferation. Analysis of human endometrial tumors reveals that CGRRF1 expression is significantly lower in hyperplasia, Grade 1, Grade 2, Grade 3, MMMT, and UPSC endometrial tumors compared to normal human endometrium (p<0.05), suggesting that loss of CGRRF1 is associated with the presence of disease.

CONCLUSION

CGRRF1 represents a novel, reproducible tissue marker of metformin response in the obese endometrium. Furthermore, our preliminary data suggests that up-regulation of CGRRF1 expression may prove clinically useful in the prevention or treatment of endometrial cancer.