Metformin modulates human leukocyte/endothelial cell interactions and proinflammatory cytokines in polycystic ovary syndrome patients

Metformin in gynecological disorders: pathogenic insights and therapeutic implications

Metformin, the most widely used anti-diabetic drug, has been demonstrated to exert various effects, including antioxidant, anti-inflammatory, anti-tumor, and cardioprotective properties. Due to its affordability and low toxicity profile, metformin is increasingly used to prevent or treat a wide range of gynecological disorders, as evidenced by epidemiological studies, clinical trials, and animal and in vitro studies. Trial findings for non-cancer conditions such as endometriosis, premature ovarian failure (POF), and uterine fibroids remain controversial and insufficient. However, most current clinical trials for polycystic ovarian syndrome (PCOS) and gynecological malignancies are ongoing phase II-III trials. The pharmacological effects of metformin have been shown to target the insulin-like growth factor (IGF), AMP-activated protein kinase (AMPK), phosphatidylinositol 3-kinase (PI3K)/AKT, MAPK, NF-κB, and other signal transduction pathways, highlighting its potential in the treatment of gynecological disorders. In this review, we discuss the biological impacts of metformin and the mechanisms of action pertinent to the treatment of different gynecological disorders.

Preadmission Metformin Use Is Associated with Reduced Mortality in Patients with Diabetes Mellitus Hospitalized with COVID-19

BACKGROUND

Observational studies have reported an association between metformin and improved outcomes in COVID-19, but most have been small and with significant limitations.

OBJECTIVE

To evaluate the association between preadmission metformin exposure and mortality in patients with diabetes mellitus hospitalized with coronavirus disease 2019 (COVID-19) infection.

DESIGN

Retrospective cohort analysis using electronic health records extracted from the American Heart Association COVID-19 Registry.

PARTICIPANTS

Adults (n = 11,993) with diabetes mellitus but without chronic kidney disease (CKD) or need for hemodialysis who were hospitalized with COVID-19 between January 25, 2020, and February 9, 2022.

MAIN MEASURES

We used propensity score modeling to address differences between metformin and non-metformin users prior to multivariable log-binomial models to examine the association between metformin use at time of hospital admission for COVID-19 infection and in-hospital death; composite of in-hospital death or discharge to hospice; composite of in-hospital death, discharge to hospice, or ICU admission; and composite of in-hospital death, discharge to hospice, ICU admission, or mechanical ventilation.

KEY RESULTS

Compared to metformin non-use, pre-admission metformin use was associated with lower risk of in-hospital death (risk ratio (RR) 0.81 [95% CI 0.75-0.90]); composite of in-hospital death or discharge to hospice (RR 0.79 [95% CI 0.74-0.87]); composite of in-hospital death, discharge to hospice, or ICU admission (RR 0.90 [95% CI 0.86-0.95]); and composite of in-hospital death, discharge to hospice, ICU admission, or mechanical ventilation (RR 0.9 [95% CI 0.84-0.98]). Metformin use was also associated with lower risk of death due to respiratory cause (RR 0.86 [95% CI 0.74-0.97]) but not cardiovascular (RR 0.84 [95% CI 0.58-1.2]) or other (RR 0.78 [95% CI 0.60-1.0]) causes.

CONCLUSIONS

Pre-admission metformin use was associated with lower risk of in-hospital mortality and markers of disease severity among adults with diabetes mellitus without CKD and not requiring hemodialysis who were hospitalized with COVID-19 infection.

Association Between Metformin Use in Early Gestational or Type 2 Diabetes in Pregnancy and Preterm Preeclampsia

OBJECTIVE

To estimate the association between maternal metformin use for the treatment of early gestational or pre-existing type 2 diabetes and preterm preeclampsia.

METHODS

This is a planned secondary analysis of the MOMPOD study (Medical Optimization of Management of Overt Type 2 Diabetes in Pregnancy), a randomized trial comparing the effect of adding metformin with insulin treatment on composite neonatal outcome in singleton pregnancies with early gestational or type 2 diabetes. Participants were randomized at 11-23 weeks of gestation to 1,000 mg metformin twice daily or placebo until delivery. A subset of participants had maternal blood collected at 24-30 weeks of gestation, and serum soluble endoglin, apolipoprotein B, vascular cell adhesion molecule-1, soluble fms-like tyrosine kinase 1, placental growth factor, high-sensitivity C-reactive protein, adiponectin, and vascular endothelial growth factor levels were measured. Our primary outcome was preterm preeclampsia , defined as preeclampsia requiring delivery before 37 weeks of gestation. Secondary outcomes included preterm preeclampsia requiring delivery before 34 weeks of gestation and differences in serum biomarkers. Multivariable regression analysis was used to estimate the associations between metformin use and primary or secondary study outcomes.

RESULTS

Of 831 participants, 119 (14.3%) developed preeclampsia requiring delivery before 37 weeks of gestation: 57 of 416 (13.7%) in the placebo group and 62 of 415 (14.9%) in the metformin group. Thirty-seven (4.4%) developed preeclampsia requiring delivery before 34 weeks of gestation: 15 (3.6%) receiving placebo and 22 (5.3%) receiving metformin. Compared with placebo, metformin was not associated with a significant difference in the occurrence of preeclampsia before 37 weeks of gestation (adjusted odds ratio [aOR] 1.04, 95% CI, 0.70-1.56) or before 34 weeks (aOR 1.43, 95% CI, 0.73-2.81). Similarly, there was no association between maternal metformin use and serum biomarker levels.

CONCLUSION

Among parturients with early gestational or pre-existing type 2 diabetes, the addition of metformin to insulin was not associated with lower odds of preterm preeclampsia or with serum biomarkers associated with cardiovascular disease risk.

Mechanisms of endothelial activation, hypercoagulation and thrombosis in COVID-19: a link with diabetes mellitus

Early since the onset of the COVID-19 pandemic, the medical and scientific community were aware of extra respiratory actions of SARS-CoV-2 infection. Endothelitis, hypercoagulation, and hypofibrinolysis were identified in COVID-19 patients as subsequent responses of endothelial dysfunction. Activation of the endothelial barrier may increase the severity of the disease and contribute to long-COVID syndrome and post-COVID sequelae. Besides, it may cause alterations in primary, secondary, and tertiary hemostasis. Importantly, these responses have been highly decisive in the evolution of infected patients also diagnosed with diabetes mellitus (DM), who showed previous endothelial dysfunction. In this review, we provide an overview of the potential triggers of endothelial activation related to COVID-19 and COVID-19 under diabetic milieu. Several mechanisms are induced by both the viral particle itself and by the subsequent immune-defensive response (i.e., NF-κB/NLRP3 inflammasome pathway, vasoactive peptides, cytokine storm, NETosis, activation of the complement system). Alterations in coagulation mediators such as factor VIII, fibrin, tissue factor, the von Willebrand factor: ADAMST-13 ratio, and the kallikrein-kinin or plasminogen-plasmin systems have been reported. Moreover, an imbalance of thrombotic and thrombolytic (tPA, PAI-I, fibrinogen) factors favors hypercoagulation and hypofibrinolysis. In the context of DM, these mechanisms can be exacerbated leading to higher loss of hemostasis. However, a series of therapeutic strategies targeting the activated endothelium such as specific antibodies or inhibitors against thrombin, key cytokines, factor X, complement system, the kallikrein-kinin system or NETosis, might represent new opportunities to address this hypercoagulable state present in COVID-19 and DM. Antidiabetics may also ameliorate endothelial dysfunction, inflammation, and platelet aggregation. By improving the microvascular pathology in COVID-19 and post-COVID subjects, the associated comorbidities and the risk of mortality could be reduced.

Metformin may be a viable adjunctive therapeutic option to potentially enhance immune reconstitution in HIV-positive immunological non-responders

ABSTRACT

Incomplete immune reconstitution remains a global challenge for human immunodeficiency virus (HIV) treatment in the present era of potent antiretroviral therapy (ART), especially for those individuals referred to as immunological non-responders (INRs), who exhibit dramatically low CD4 + T-cell counts despite the use of effective antiretroviral therapy, with long-term inhibition of viral replication. In this review, we provide a critical overview of the concept of ART-treated HIV-positive immunological non-response, and also explain the known mechanisms which could potentially account for the emergence of immunological non-response in some HIV-infected individuals treated with appropriate and effective ART. We found that immune cell exhaustion, combined with chronic inflammation and the HIV-associated dysbiosis syndrome, may represent strategic aspects of the immune response that may be fundamental to incomplete immune recovery. Interestingly, we noted from the literature that metformin exhibits properties and characteristics that may potentially be useful to specifically target immune cell exhaustion, chronic inflammation, and HIV-associated gut dysbiosis syndrome, mechanisms which are now recognized for their critically important complicity in HIV disease-related incomplete immune recovery. In light of evidence discussed in this review, it can be seen that metformin may be of particularly favorable use if utilized as adjunctive treatment in INRs to potentially enhance immune reconstitution. The approach described herein may represent a promising area of therapeutic intervention, aiding in significantly reducing the risk of HIV disease progression and mortality in a particularly vulnerable subgroup of HIV-positive individuals.

Metformin sensitizes leukemic cells to cytotoxic lymphocytes by increasing expression of intercellular adhesion molecule-1 (ICAM-1)

Solid tumor cells have an altered metabolism that can protect them from cytotoxic lymphocytes. The anti-diabetic drug metformin modifies tumor cell metabolism and several clinical trials are testing its effectiveness for the treatment of solid cancers. The use of metformin in hematologic cancers has received much less attention, although allogeneic cytotoxic lymphocytes are very effective against these tumors. We show here that metformin induces expression of Natural Killer G2-D (NKG2D) ligands (NKG2DL) and intercellular adhesion molecule-1 (ICAM-1), a ligand of the lymphocyte function-associated antigen 1 (LFA-1). This leads to enhance sensitivity to cytotoxic lymphocytes. Overexpression of anti-apoptotic Bcl-2 family members decrease both metformin effects. The sensitization to activated cytotoxic lymphocytes is mainly mediated by the increase on ICAM-1 levels, which favors cytotoxic lymphocytes binding to tumor cells. Finally, metformin decreases the growth of human hematological tumor cells in xenograft models, mainly in presence of monoclonal antibodies that recognize tumor antigens. Our results suggest that metformin could improve cytotoxic lymphocyte-mediated therapy.

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

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

Metformin Exposure and Risk of Hypertensive Disorders of Pregnancy in Patients with Type 2 Diabetes

OBJECTIVE

Metformin has been found to have a role in promoting vascular remodeling and angiogenesis which may reduce the risk of developing preeclampsia. Prior studies have shown a decrease in the incidence of hypertensive disorders of pregnancy in patients with type 2 and gestational diabetes taking metformin. We hypothesize metformin exposure decreases the risk of developing hypertension in patients with type 2 diabetes.

STUDY DESIGN

Retrospective cohort study from 2009 to 2019 of singleton pregnancies was complicated by type 2 diabetes. We compared patients who received metformin throughout pregnancy to those with no metformin exposure. The primary outcome was a hypertension composite defined as gestational hypertension, preeclampsia with or without severe features, HELLP syndrome, or eclampsia. Individual hypertensive outcomes and neonatal outcomes were secondarily evaluated. Logistic regression was used to adjust for confounding variables.

RESULTS

A total of 254 pregnancies were included. Women exposed to metformin were significantly less likely to develop hypertension composite compared with nonexposed women (22.7 vs. 33.1%, aOR 0.53, 95% CI 0.29-0.96). The incidence of preeclampsia with severe features was also significantly lower in those who received metformin compared with those who did not (12.1 vs. 20.7%, aOR 0.38, 95% CI 0.18-0.81). There were no differences in preterm birth prior to 34 or 37 weeks, fetal growth restriction, or birth weight between the study groups. A subgroup analysis of women without chronic hypertension also had a significantly lower risk of developing preeclampsia with severe features (7.6 vs. 17.8%, aOR 0.35, 95% CI 0.13-0.94).

CONCLUSION

Metformin exposure was associated with a decreased risk of composite hypertensive disorders of pregnancy in patients with pregestational type 2 diabetes. These data suggest that there may be benefit to metformin administration beyond glycemic control in this patient population.

KEY POINTS

· Metformin use showed a decreased risk of a hypertension composite.. · Results were consistent in patients without chronic hypertension.. · Metformin may show benefit beyond glycemic control in women with type 2 diabetes..

Does endothelial dysfunction correlate with endocrinal abnormalities in patients with polycystic ovary syndrome?

To study and critically analyze the published evidence on correlation of hormonal abnormalities and endothelial dysfunction (ED) in polycystic ovary syndrome (PCOS) through a systematic review. The databases including MEDLINE, PubMed, Up-To-Date, and Science Direct were searched using Medical subject handling terms and free text term keywords such as endocrine abnormalities in PCOS, ED assessment in PCOS, ED in combination with insulin resistance (IR), hyperandrogenism (HA), increased free testosterone, free androgen index (FAI), gonadotrophin levels, luteinizing hormone (LH), prolactin, estrogen, adipocytokines to search trials, and observational studies published from January 1987 to September 2015. Authors of original studies were contacted for additional data when necessary. PCOS increases the risk of cardiovascular disease in women. ED, which is a reliable indicator of cardiovascular risk in general population, is seen in most (but not all) women with PCOS. IR, seen in 70% patients with PCOS, is associated with ED in these women, but patients can have normal endothelial function even in the presence of IR. Free testosterone and FAI are consistently associated with ED, but endothelial function can be normal despite HA. Estradiol (not estrone) appears to be protective against ED though estrone is the predominant estrogen produced in PCOS. Increased levels of adipocytokines (visfatin) are promising in predicting ED and cardiovascular risk. However, more studies are required focusing on direct correlation of levels of prolactin, LH, estrone, and visfatin with ED in PCOS.

Novel Insights and Current Evidence for Mechanisms of Atherosclerosis: Mitochondrial Dynamics as a Potential Therapeutic Target

Cardiovascular disease (CVD) is the main cause of death worldwide. Atherosclerosis is the underlying pathological basis of CVD. Mitochondrial homeostasis is maintained through the dynamic processes of fusion and fission. Mitochondria are involved in many cellular processes, such as steroid biosynthesis, calcium homeostasis, immune cell activation, redox signaling, apoptosis, and inflammation, among others. Under stress conditions, mitochondrial dynamics, mitochondrial cristae remodeling, and mitochondrial ROS (mitoROS) production increase, mitochondrial membrane potential (MMP) decreases, calcium homeostasis is imbalanced, and mitochondrial permeability transition pore open (mPTP) and release of mitochondrial DNA (mtDNA) are activated. mtDNA recognized by TLR9 can lead to NF-κB pathway activation and pro-inflammatory factor expression. At the same time, TLR9 can also activate NLRP3 inflammasomes and release interleukin, an event that eventually leads to tissue damage and inflammatory responses. In addition, mitochondrial dysfunction may amplify the activation of NLRP3 through the production of mitochondrial ROS, which together aggravate accumulating mitochondrial damage. In addition, mtDNA defects or gene mutation can lead to mitochondrial oxidative stress. Finally, obesity, diabetes, hypertension and aging are risk factors for the progression of CVD, which are closely related to mitochondrial dynamics. Mitochondrial dynamics may represent a new target in the treatment of atherosclerosis. Antioxidants, mitochondrial inhibitors, and various new therapies to correct mitochondrial dysfunction represent a few directions for future research on therapeutic intervention and amelioration of atherosclerosis.

LILAC pilot study: Effects of metformin on mTOR activation and HIV reservoir persistence during antiretroviral therapy

BACKGROUND

Chronic inflammation and residual HIV transcription persist in people living with HIV (PLWH) receiving antiretroviral therapy (ART), thus increasing the risk of developing non-AIDS co-morbidities. The mechanistic target of rapamycin (mTOR) is a key regulator of cellular metabolism and HIV transcription, and therefore represents an interesting novel therapeutic target.

METHODS

The LILAC pilot clinical trial, performed on non-diabetic ART-treated PLWH with CD4⁺/CD8⁺ T-cell ratios <0.8, evaluated the effects of metformin (12 weeks oral administration; 500-850 mg twice daily), an indirect mTOR inhibitor, on the dynamics of immunological/virological markers and changes in mTOR activation/phosphorylation in blood collected at Baseline, Week 12, and 12 weeks after metformin discontinuation (Week 24) and sigmoid colon biopsies (SCB) collected at Baseline and Week 12.

FINDINGS

CD4⁺ T-cell counts, CD4⁺/CD8⁺ T-cell ratios, plasma markers of inflammation/gut damage, as well as levels of cell-associated integrated HIV-DNA and HIV-RNA, and transcriptionally-inducible HIV reservoirs, underwent minor variations in the blood in response to metformin. The highest levels of mTOR activation/phosphorylation were observed in SCB at Baseline. Consistently, metformin significantly decreased CD4⁺ T-cell infiltration in the colon, as well as mTOR activation/phosphorylation, especially in CD4⁺ T-cells expressing the Th17 marker CCR6. Also, metformin decreased the HIV-RNA/HIV-DNA ratios, a surrogate marker of viral transcription, in colon-infiltrating CD4⁺ T-cells of 8/13 participants.

INTERPRETATION

These results are consistent with the fact that metformin preferentially acts on the intestine and that mTOR activation/phosphorylation selectively occurs in colon-infiltrating CCR6⁺CD4⁺ T-cells. Future randomized clinical trials should evaluate the benefits of long-term metformin supplementation of ART.

The Fatty Acid Lipid Metabolism Nexus in COVID-19

Enteric symptomology seen in early-stage severe acute respiratory syndrome (SARS)-2003 and COVID-19 is evidence of virus replication occurring in the intestine, liver and pancreas. Aberrant lipid metabolism in morbidly obese individuals adversely affects the COVID-19 immune response and increases disease severity. Such observations are in line with the importance of lipid metabolism in COVID-19, and point to the gut as a site for intervention as well as a therapeutic target in treating the disease. Formation of complex lipid membranes and palmitoylation of coronavirus proteins are essential during viral replication and assembly. Inhibition of fatty acid synthase (FASN) and restoration of lipid catabolism by activation of AMP-activated protein kinase (AMPK) impede replication of coronaviruses closely related to SARS-coronavirus-2 (CoV-2). In vitro findings and clinical data reveal that the FASN inhibitor, orlistat, and the AMPK activator, metformin, may inhibit coronavirus replication and reduce systemic inflammation to restore immune homeostasis. Such observations, along with the known mechanisms of action for these types of drugs, suggest that targeting fatty acid lipid metabolism could directly inhibit virus replication while positively impacting the patient's response to COVID-19.

Repurposing Metformin in Nondiabetic People With HIV: Influence on Weight and Gut Microbiota

Background

People with HIV (PWH) taking antiretroviral therapy (ART) may experience weight gain, dyslipidemia, increased risk of non-AIDS comorbidities, and long-term alteration of the gut microbiota. Both low CD4/CD8 ratio and chronic inflammation have been associated with changes in the gut microbiota of PWH. The antidiabetic drug metformin has been shown to improve gut microbiota composition while decreasing weight and inflammation in diabetes and polycystic ovary syndrome. Nevertheless, it remains unknown whether metformin may benefit PWH receiving ART, especially those with a low CD4/CD8 ratio.

Methods

In the Lilac pilot trial, we recruited 23 nondiabetic PWH receiving ART for more than 2 years with a low CD4/CD8 ratio (<0.7). Blood and stool samples were collected during study visits at baseline, after a 12-week metformin treatment, and 12 weeks after discontinuation. Microbiota composition was analyzed by 16S rDNA gene sequencing, and markers of inflammation were assessed in plasma.

Results

Metformin decreased weight in PWH, and weight loss was inversely correlated with plasma levels of the satiety factor GDF-15. Furthermore, metformin changed the gut microbiota composition by increasing the abundance of anti-inflammatory bacteria such as butyrate-producing species and the protective Akkermansia muciniphila.

Conclusions

Our study provides the first evidence that a 12-week metformin treatment decreased weight and favored anti-inflammatory bacteria abundance in the microbiota of nondiabetic ART-treated PWH. Larger randomized placebo-controlled clinical trials with longer metformin treatment will be needed to further investigate the role of metformin in reducing inflammation and the risk of non-AIDS comorbidities in ART-treated PWH.

Metformin reduces saturated fatty acid-induced lipid accumulation and inflammatory response by restoration of autophagic flux in endothelial cells

Autophagy, an integral part of the waste recycling process, plays an important role in cellular physiology and pathophysiology. Impaired autophagic flux causes ectopic lipid deposition, which is defined as the accumulation of lipids in non-adipose tissue. Ectopic lipid accumulation is observed in patients with cardiometabolic syndrome, including obesity, diabetes, insulin resistance, and cardiovascular complications. Metformin is the first line of treatment for type 2 diabetes, and one of the underlying mechanisms for the anti-diabetic effect of metformin is mediated by the stimulation of AMP-activated protein kinase (AMPK). Because the activation of AMPK is crucial for the initiation of autophagy, we hypothesize that metformin reduces the accumulation of lipid droplets by increasing autophagic flux in vascular endothelial cells. Incubation of vascular endothelial cells with saturated fatty acid (SFA) increased the accumulation of lipid droplets and impaired autophagic flux. We observed that the accumulation of lipid droplets was reduced, and the autophagic flux was enhanced by treatment with metformin. The knock-down of AMPKα by using siRNA blunted the effect of metformin. Furthermore, treatment with SFA or inhibition of autophagy increased leukocyte adhesion, whereas treatment with metformin decreased the SFA-induced leukocyte adhesion. The results suggest a novel mechanism by which metformin protects vascular endothelium from SFA-induced ectopic lipid accumulation and pro-inflammatory responses. In conclusion, improving autophagic flux may be a therapeutic strategy to protect endothelial function from dyslipidemia and diabetic complications.

Background and Proposed Design for a Metformin Abdominal Aortic Aneurysm Suppression Trial

Abdominal aortic aneurysm (AAA) may lead to rupture and death if left untreated. While endovascular or surgical repair is generally recommended for AAA greater than 5–5.5 cm, the vast majority of aneurysms detected by screening modalities are smaller than this threshold. Once discovered, there would be a significant potential benefit in suppressing the growth of these small aneurysms in order to obviate the need for repair and mitigate rupture risk. Patients with diabetes, in particular those taking the oral hypoglycaemic medication metformin, have been shown to have lower incidence, growth rate, and rupture risk of AAA. Metformin therefore represents a widely available, non-toxic, potential inhibitor of AAA growth, but thus far no prospective clinical studies have evaluated this. Here, we present the background, rationale, and design for a randomised, double-blind, placebo-controlled clinical trial of metformin for growth suppression in patients with small AAA.

The effects of empagliflozin vs metformin on endothelial microparticles in overweight/obese women with polycystic ovary syndrome

CONTEXT

Endothelial microparticles (EMPs) are novel, surrogate biomarkers of endothelial function and have been shown to be elevated in women with polycystic ovary syndrome (PCOS). It remains poorly understood how pharmacological options for managing PCOS affect EMP levels.

OBJECTIVE

To characterise and compare the effects of empagliflozin vs metformin on the circulating levels of EMPs in overweight/obese women with PCOS.

METHODS

This was a randomised, comparative, 12-week single-centre trial conducted at the Academic Diabetes, Endocrinology and Metabolism Research Centre, Hull, UK. This analysis includes data from 39 overweight/obese women with PCOS who completed the study and were randomised to empagliflozin (15 mg/day) (n = 19) or metformin (1500 mg/day) (n = 20). Blood samples were collected at baseline and 12 weeks after treatment and analysed for specific surface proteins (ICAM-1, VCAM-1, PECAM-1, E-selectin and endoglin) expressed by circulating EMPs using flow cytometry.

RESULTS

In the empagliflozin group, ICAM-1 (P = 0.006), E-selectin (P = 0.016) and VCAM-1 (P = 0.001) EMPs increased significantly following 12 weeks of treatment, but no changes were seen in PECAM-1 (P = 0.93) or endoglin (P = 0.13) EMPs. In the metformin group, VCAM-1 EMPs (P < 0.001) increased significantly after 12 weeks of treatment, whereas all other EMPs remained unchanged. When data were expressed as percentage change from baseline in each group, no significant differences were seen between groups for any biomarker (P-values from 0.22 to 0.80).

CONCLUSIONS

Short-term administration of empagliflozin and metformin in overweight/obese women with PCOS appear to increase EMPs expressed by endothelial cells during their activation.

Metformin effect on gut microbiota: insights for HIV-related inflammation

The gut microbiota is emerging as a prominent player in maintaining health through several metabolic and immune pathways. Dysregulation of gut microbiota composition, also known as dysbiosis, is involved in the clinical outcome of diabetes, inflammatory bowel diseases, cancer, aging and HIV infection. Gut dysbiosis and inflammation persist in people living with HIV (PLWH) despite receiving antiretroviral therapy, further contributing to non-AIDS comorbidities. Metformin, a widely used antidiabetic agent, has been found to benefit microbiota composition, promote gut barrier integrity and reduce inflammation in human and animal models of diabetes. Inspired by the effect of metformin on diabetes-related gut dysbiosis, we herein critically review the relevance of metformin to control inflammation in PLWH. Metformin may improve gut microbiota composition, in turn reducing inflammation and risk of non-AIDS comorbidities. This review will pave the way towards innovative strategies to counteract dysregulated microbiota and improve the lives of PLWH.

GDF-15 as a Weight Watcher for Diabetic and Non-Diabetic People Treated With Metformin

Weight gain and obesity are global health concerns contributing to morbidity with increased risks of cardiovascular disease, diabetes, liver steatohepatitis and cancer. Pharmacological therapies or bariatric surgery are often required for those who fail to adhere to diet and lifestyle modifications. Metformin, a widely used antidiabetic agent, seems to have a health benefit beyond its anti-hyperglycemic properties, with few side effects. Emerging evidence shows weight loss to be associated with metformin in both diabetic and non-diabetic individuals. Recently, the growth differentiation factor 15 (GDF-15), a member of the transforming growth factor beta superfamily, has been identified as a key mediator of metformin-induced weight loss. Metformin increases the secretion of GDF-15, which binds exclusively to glial cell-derived neurotrophic factor family receptor alpha-like (GFRAL). This gut-brain cytokine works as a prominent player in reducing food intake and body weight in health and disease, like anorexia nervosa and cancer. Herein, we critically review advances in the understanding of the weight-reducing effects of metformin via the GDF-15 pathway.

Effect of metformin on the size of the HIV reservoir in non-diabetic ART-treated individuals: single-arm non-randomised Lilac pilot study protocol

INTRODUCTION

People living with HIV (PLWH) on antiretroviral therapy (ART) do not progress to AIDS. However, they still suffer from an increased risk of inflammation-associated complications. HIV persists in long-lived CD4+ T cells, which form the major viral reservoir. The persistence of this reservoir despite long-term ART is the major hurdle to curing HIV. Importantly, the size of the HIV reservoir is larger in individuals who start ART late in the course of infection and have a low CD4+/CD8+ ratio. HIV reservoir size is also linked to the levels of persistent inflammation on ART. Thus, novel strategies to reduce immune inflammation and improve the host response to control the HIV reservoir would be a valuable addition to current ART. Among the different strategies under investigation is metformin, a widely used antidiabetic drug that was recently shown to modulate T-cell activation and inflammation. Treatment of non-diabetic individuals with metformin controls inflammation by improving glucose metabolism and by regulating intracellular immunometabolic checkpoints such as the adenosin 5 monophosphate activated protein kinase and mammalian target of rapamycin, in association with microbiota modification.

METHODS AND ANALYSIS

22 PLWH on ART for more than 3 years, at high risk of inflammation or the development of non-AIDS events (low CD4+/CD8+ ratio) will be recruited in a clinical single-arm pilot study. We will test whether supplementing ART with metformin in non-diabetic HIV-infected individuals can reduce the size of the HIV reservoir as determined by various virological assays. The expected outcome of this study is a reduction in both the size of the HIV reservoir and inflammation following the addition of metformin to ART, thus paving the way towards HIV eradication.

ETHICS AND DISSEMINATION

Ethical approval: McGill university Health Centre committee number MP-37-2016-2456. Canadian Canadian Institutes of Health Research/Canadian HIV Trials Network (CTN) protocol CTNPT027. Results will be made available through publication in peer-reviewed journals and through the CTN website.

TRIAL REGISTRATION NUMBER

NCT02659306.

Metformin prescription status and abdominal aortic aneurysm disease progression in the U.S. veteran population

BACKGROUND

Identification of a safe and effective medical therapy for abdominal aortic aneurysm (AAA) disease remains a significant unmet medical need. Recent small cohort studies indicate that metformin, the world's most commonly prescribed oral hypoglycemic agent, may limit AAA enlargement. We sought to validate these preliminary observations in a larger cohort.

METHODS

All patients with asymptomatic AAA disease managed in the Veterans Affairs Health Care System between 2003 and 2013 were identified by International Classification of Diseases, Ninth Revision codes. Those with a concomitant diagnosis of diabetes mellitus who also received two or more abdominal imaging studies (computed tomography, magnetic resonance imaging, or ultrasound) documenting the presence and size of an AAA, separated by at least 1 year, were included for review. Maximal AAA diameters were determined from radiologic reports. Further data acquisition was censored after surgical AAA repair, when performed. Comorbidities, active smoking status, and outpatient medication records (within 6 months of AAA diagnosis) were also queried. Yearly AAA enlargement rates, as a function of metformin treatment status, were compared using two statistical models expressed in millimeters per year: a multivariate linear regression (model 1) and a multivariate mixed-effects model with random intercept and random slope (model 2).

RESULTS

A total of 13,834 patients with 58,833 radiographic records were included in the analysis, with radiology imaging follow-up of 4.2 ± 2.6 years (mean ± standard deviation). The average age of the patients at AAA diagnosis was 69.8 ± 7.8 years, and 39.7% had a metformin prescription within ±6 months of AAA. The mean growth rate for AAAs in the entire cohort was 1.4 ± 2.0 mm/y by model 1 analysis and 1.3 ± 1.6 mm/y by model 2 analysis. The unadjusted mean rate of AAA growth was 1.2 ± 1.9 mm/y for patients prescribed metformin compared with 1.5 ± 2.2 mm/y for those without (P < .001), a 20% decrease. This effect remained significant when adjusted for variables relevant on AAA progression: metformin prescription was associated with a reduction in yearly AAA growth rate of -0.23 mm (95% confidence interval, -0.35 to -0.16; P < .001) by model 1 analysis and 0.20 mm/y (95% confidence interval, -0.26 to -0.14; P < .001) by model 2 analysis. A subset analysis of 7462 patients with baseline AAA size of 35 to 49 mm showed a similar inhibitory effect (1.4 ± 2.0 mm/y to 1.7 ± 2.2 mm/y; P < .001). Patients' factors associated with an increased yearly AAA growth rate were baseline AAA size, metastatic solid tumors, active smoking, chronic obstructive pulmonary disease, and chronic renal disease. Factors associated with decreased yearly AAA growth rates included prescriptions for angiotensin II type 1 receptor blockers or sulfonylureas and the presence of diabetes-related complications.

CONCLUSIONS

In a nationwide analysis of diabetic Veterans Affairs patients, prescription for metformin was associated with decreased AAA enlargement. These findings provide further support for the conduct of prospective clinical trials to test the ability of metformin to limit progression of early AAA disease.

Protective effects of metformin on lipopolysaccharide‑induced airway epithelial cell injury via NF‑κB signaling inhibition

Asthma is a heterogeneous disease characterized by chronic airway inflammation. It has been demonstrated that metformin, an extensively used drug for the treatment of type 2 diabetes, improves airway inflammation and remodeling. However, the mechanism by which this occurs remains poorly understood. The present study investigated the protective effects of metformin in lipopolysaccharide (LPS)‑induced human bronchial epithelial (16HBE) cells injury and the associated mechanisms. 16HBE cells were preincubated with metformin for 1 h and subsequently exposed to LPS for 12 h. A lactate dehydrogenase (LDH) leakage assay was used to determine the extent of injury to 16HBE cells. The expression of tumor necrosis factor‑α (TNF‑α) and interleukin‑6 (IL‑6) was measured by ELISA. The protein expression of intercellular adhesion molecule‑1 (ICAM‑1) and vascular cell adhesion molecule‑1 (VCAM‑1), as well as proteins associated with nuclear factor (NF)‑κB signaling, was measured by western blotting. Immunofluorescence assays confirmed the nuclear translocation of NF‑κB p65. The LDH leakage assays suggested that metformin significantly reduced LPS‑induced 16HBE cell injury. Furthermore, it was confirmed that metformin suppressed the LPS‑induced secretion of TNF‑α, IL‑6, ICAM‑1 and VCAM‑1. The mechanism occurred at least partially via inhibition of NF‑κB signaling. The results demonstrated that metformin inhibited NF‑κB mRNA expression and the nuclear translocation of NF‑κB p65. To the best of our knowledge, the present study was the first to demonstrate that metformin ameliorated LPS‑induced bronchial epithelial cell injury via NF‑κB signaling suppression.

Metformin-induced anticancer activities: recent insights

Metformin is a widely used antidiabetic drug, and there is evidence among diabetic patients that metformin is a chemopreventive agent against multiple cancers. There is also evidence in human studies that metformin is a cancer chemotherapeutic agent, and several clinical trials that use metformin alone or in combination with other drugs are ongoing. In vivo and in vitro cancer cell culture studies demonstrate that metformin induces both AMPK-dependent and AMPK-independent genes/pathways that result in inhibition of cancer cell growth and migration and induction of apoptosis. The effects of metformin in cancer cells resemble the patterns observed after treatment with drugs that downregulate specificity protein 1 (Sp1), Sp3 and Sp4 or by knockdown of Sp1, Sp3 and Sp4 by RNA interference. Studies in pancreatic cancer cells clearly demonstrate that metformin decreases expression of Sp1, Sp3, Sp4 and pro-oncogenic Sp-regulated genes, demonstrating that one of the underlying mechanisms of action of metformin as an anticancer agent involves targeting of Sp transcription factors. These observations are consistent with metformin-mediated effects on genes/pathways in many other tumor types.

Metformin, the aspirin of the 21st century: its role in gestational diabetes mellitus, prevention of preeclampsia and cancer, and the promotion of longevity

Metformin is everywhere. Originally introduced in clinical practice as an antidiabetic agent, its role as a therapeutic agent is expanding to include treatment of prediabetes mellitus, gestational diabetes mellitus, and polycystic ovarian disease; more recently, experimental studies and observations in randomized clinical trials suggest that metformin could have a place in the treatment or prevention of preeclampsia. This article provides a brief overview of the history of metformin in the treatment of diabetes mellitus and reviews the results of metaanalyses of metformin in gestational diabetes mellitus as well as the treatment of obese, non-diabetic, pregnant women to prevent macrosomia. We highlight the results of a randomized clinical trial in which metformin administration in early pregnancy did not reduce the frequency of large-for-gestational-age infants (the primary endpoint) but did decrease the frequency of preeclampsia (a secondary endpoint). The mechanisms by which metformin may prevent preeclampsia include a reduction in the production of antiangiogenic factors (soluble vascular endothelial growth factor receptor-1 and soluble endoglin) and the improvement of endothelial dysfunction, probably through an effect on the mitochondria. Another potential mechanism whereby metformin may play a role in the prevention of preeclampsia is its ability to modify cellular homeostasis and energy disposition, mediated by rapamycin, a mechanistic target. Metformin has a molecular weight of 129 Daltons and therefore readily crosses the placenta. There is considerable evidence to suggest that this agent is safe during pregnancy. New literature on the role of metformin as a chemotherapeutic adjuvant in the prevention of cancer and in prolonging life and protecting against aging is reviewed briefly. Herein, we discuss the mechanisms of action and potential benefits of metformin.

Low testosterone levels are related to oxidative stress, mitochondrial dysfunction and altered subclinical atherosclerotic markers in type 2 diabetic male patients

INTRODUCTION

Low testosterone levels in men are associated with type 2 diabetes and cardiovascular risk. However, the role of testosterone in mitochondrial function and leukocyte-endothelium interactions is unknown. Our aim was to evaluate the relationship between testosterone levels, metabolic parameters, oxidative stress, mitochondrial function, inflammation and leukocyte-endothelium interactions in type 2 diabetic patients.

MATERIALS AND METHODS

The study was performed in 280 male type 2 diabetic patients and 50 control subjects. Anthropometric and metabolic parameters, testosterone levels, reactive oxygen species (ROS) production, mitochondrial membrane potential, TNFα, adhesion molecules and leukocyte-endothelium cell interactions were evaluated.

RESULTS

Testosterone levels were lower in diabetic patients. Total and mitochondrial ROS were increased and mitochondrial membrane potential, SOD and GSR expression levels were reduced in diabetic patients. TNFα, ICAM-1 and VCAM-1 levels, leukocyte rolling flux and adhesion were all enhanced in diabetic patients, while rolling velocity was reduced. Testosterone levels correlated negatively with glucose, HOMA-IR, HbA1c, triglycerides, nonHDL-c, ApoB, hs-CRP and AIP, and positively with HDL-c and ApoA1. The multivariable regression model showed that HDL-c, HOMA-IR and age were independently associated with testosterone. Furthermore, testosterone levels correlated positively with membrane potential and rolling velocity and negatively with ROS production, VCAM-1, rolling flux and adhesion.

CONCLUSIONS

Our data highlight that low testosterone levels in diabetic men are related to impaired metabolic profile and mitochondrial function and enhanced inflammation and leukocyte-endothelium cell interaction, which leaves said patients at risk of cardiovascular events.

Metformin Ameliorates Uterine Defects in a Rat Model of Polycystic Ovary Syndrome

Adult rats treated concomitantly with insulin and human chorionic gonadotropin exhibit endocrine, metabolic, and reproductive abnormalities that are very similar to those observed in polycystic ovary syndrome (PCOS) patients. In this study, we used this rat model to assess the effects of metformin on PCOS-related uterine dysfunction. In addition to reducing androgen levels, improving insulin sensitivity, and correcting the reproductive cycle, metformin treatment induced morphological changes in the PCOS-like uterus. At the molecular and cellular levels, metformin normalized the androgen receptor-mediated transcriptional program and restored epithelial–stromal interactions. In contrast to glucose transport, uterine inflammatory gene expression was suppressed through the PI3K–Akt–NFκB network, but without affecting apoptosis. These effects appeared to be independent of AMPK subunit and autophagy-related protein regulation. We found that when metformin treatment partially restored implantation, several implantation-related genes were normalized in the PCOS-like rat uterus. These results improve our understanding of how metformin rescues the disruption of the implantation process due to the uterine defects that result from hyperandrogenism and insulin resistance. Our data provide insights into the molecular and functional clues that might help explain, at least in part, the potential therapeutic options of metformin in PCOS patients with uterine dysfunction.

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The therapeutic dose of metformin sufficiently suppresses hyperandrogenism and insulin resistance.

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Metformin inhibits uterine androgen receptor (AR)-dependent gene expression to restore epithelial–stromal interactions.

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Metformin reduces uterine inflammation through the PI3K–Akt–NFκB pathway.

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Metformin partially restores implantation in PCOS-like rats.

The systemic benefits of metformin therapy for women with polycystic ovary syndrome (PCOS) are widely appreciated, but knowledge of the molecular mechanisms of its action and to what extent it beneficially affects uterine function is limited. Using a PCOS-like rat model, we show that treatment with metformin can reverse the negative effects of androgenic and inflammatory conditions in the rat uterus. Importantly, we find that the sustained benefit of metformin is to rescue implantation failure in some PCOS-like rats. Thus, our data will be of translational value in the clinical management of metformin treatment in PCOS patients with uterine dysfunction.

Endothelial maintenance in health and disease: Importance of sex differences

The vascular endothelium has emerged as more than just an inert monolayer of cells lining the vascular bed. It represents the interface between the blood stream and vessel wall, and has a strategic role in regulating vascular homeostasis by the release of vasoactive substances. Endothelial dysfunction contributes to the development and progression of cardiovascular disease. Recognition of sex-specific factors implicated in endothelial cell biology is important for the identification of clinically relevant preventive and/or therapeutic strategies. This review aims to give an overview of the recent advances in understanding the importance of sex specific observations in endothelial maintenance, both in healthy and diseased conditions. The female endothelium is highlighted in the context of polycystic ovary syndrome and pre-eclampsia. Furthermore, sex differences are explored in chronic kidney disease, which is currently appreciated as one of public health priorities. Overall, this review endorses integration of sex analysis in experimental and patient-oriented research in the exciting field of vascular biology.

High Serum Tumor Necrosis Factor-Alpha Levels in Women with Polycystic Ovary Syndrome: A Meta-Analysis

The objective of the study is to assess the TNF-α levels in PCOS patients and healthy controls. A comprehensive electronic search in Medline, Embase, and the Cochrane Library database was conducted up to July 2016. Random-effects model was used to estimate the standardized mean differences (SMDs) with 95% confidence intervals (CIs). Twenty-nine studies with a total of 1960 participants (1046 PCOS patients and 914 controls) were included in this meta-analysis. The TNF-α levels in PCOS patients were significantly higher than those in controls (random-effects, SMD = 0.60, 95% CI = 0.28-0.92, P<0.001). With regard to the subgroup analyses stratified by ethnicity, study quality, methods, and BMI, significantly high TNF-α levels were found in patients with PCOS in almost all of these subgroups. In the subgroup stratified by HOMA-IR ratio and T ratio, significant differences were only observed in the subgroups with HOMA-IR ratio of >1.72(SMD = 0.967, 95% CI = 0.103-1.831, P = 0.028, I2 = 93.5%) and T ratio>2.10 (SMD = 1.420, 95% CI = 0.429-2.411, P = 0.005, I2 = 96.1%). By meta-regression it was suggested that ethnicity might contribute little to the heterogeneity between the included studies. Through cumulative meta-analysis and sensitivity analysis it was supposed that the higher TNF-α levels of PCOS patients compared to healthy controls was stable and reliable. This meta-analysis suggests that the circulating TNF-α levels in women with PCOS are significantly higher than those in healthy controls. It may be involved in promoting insulin resistance and androgen excess of PCOS.

Exenatide and metformin express their anti-inflammatory effects on human monocytes/macrophages by the attenuation of MAPKs and NFκB signaling

Metformin and exenatide are effective antidiabetic drugs, and they seem to have pleiotropic properties improving cardiovascular outcomes. Macrophages' phenotype is essential in the development of atherosclerosis, and it can be modified during antidiabetic therapy, resulting in attenuated atherogenesis. The mechanism orchestrating this phenomenon is not fully clear. We examined the impact of exenatide and metformin on the level of TNF alpha, MCP-1, reactive oxygen species (ROS), and the activation of mitogen-activated protein kinases (MAPK), nuclear factor kappa B (NFκB), and CCAAT/enhancer-binding protein beta (C/EBP beta) in human monocytes/macrophages. We found that both drugs reduced levels of TNF alpha, ROS, and NFκB binding activity to a similar extent. Compared to metformin, exenatide was more effective in reducing MCP-1 levels. We noted that Compound C (AMPK inhibitor) reduced the impact of exenatide on cytokines, ROS, and NFκB in cultures. Both drugs elevated the C/EBP beta phosphorylation level. Experiments on MAPKs showed effective inhibitory potential of exenatide toward p38, JNK, and ERK, whereas metformin inhibited JNK and ERK only. Exenatide was more effective in the inhibition of JNK than metformin. Interestingly, an in vitro setting additive effect of drugs was absent. In conclusion, here, we report that metformin and exenatide inhibit the proinflammatory phenotype of human monocytes/macrophages via influence on MAPK, C/EBP beta, and NFκB. Exenatide was more effective than metformin in reducing MCP-1 expression and JNK activity. We also showed that some effects of exenatide relied on AMPK activation. This shed light on the possible mechanisms responsible for pleiotropic effects of metformin and exenatide.

Metformin treatment status and abdominal aortic aneurysm disease progression

OBJECTIVE

In population-based studies performed on multiple continents during the past two decades, diabetes mellitus has been negatively associated with the prevalence and progression of abdominal aortic aneurysm (AAA) disease. We investigated the possibility that metformin, the primary oral hypoglycemic agent in use worldwide, may influence the progression of AAA disease.

METHODS

Preoperative AAA patients with diabetes were identified from an institutional database. After tabulation of individual cardiovascular and demographic risk factors and prescription drug regimens, odds ratios for categorical influences on annual AAA enlargement were calculated through nominal logistical regression. Experimental AAA modeling experiments were subsequently performed in normoglycemic mice to validate the database-derived observations as well as to suggest potential mechanisms of metformin-mediated aneurysm suppression.

RESULTS

Fifty-eight patients met criteria for study inclusion. Of 11 distinct classes of medication considered, only metformin use was negatively associated with AAA enlargement. This association remained significant after controlling for gender, age, cigarette smoking status, and obesity. The median enlargement rate in AAA patients not taking oral diabetic medication was 1.5 mm/y; by nominal logistic regression, metformin, hyperlipidemia, and age ≥70 years were associated with below-median enlargement, whereas sulfonylurea therapy, initial aortic diameter ≥40 mm, and statin use were associated with above-median enlargement. In experimental modeling, metformin dramatically suppressed the formation and progression, with medial elastin and smooth muscle preservation and reduced aortic mural macrophage, CD8 T cell, and neovessel density.

CONCLUSIONS

Epidemiologic evidence of AAA suppression in diabetes may be attributable to concurrent therapy with the oral hypoglycemic agent metformin.