Metformin prevents methylglyoxal-induced apoptosis by suppressing oxidative stress in vitro and in vivo

Integrated approach to reducing polypharmacy in older people: exploring the role of oxidative stress and antioxidant potential therapy

Increased life expectancy, attributed to improved access to healthcare and drug development, has led to an increase in multimorbidity, a key contributor to polypharmacy. Polypharmacy is characterised by its association with a variety of adverse events in the older persons. The mechanisms involved in the development of age-related chronic diseases are largely unknown; however, altered redox homeostasis due to ageing is one of the main theories. In this context, the present review explores the development and interaction between different age-related diseases, mainly linked by oxidative stress. In addition, drug interactions in the treatment of various diseases are described, emphasising that the holistic management of older people and their pathologies should prevail over the individual treatment of each condition.

An integrated investigation of sulfotransferases (SULTs) in hepatocellular carcinoma and identification of the role of SULT2A1 on stemness

The cytosolic sulfotransferases (SULTs) are phase II conjugating enzymes, which are widely expressed in the liver and mainly mediate the sulfation of numerous xenobiotics and endogenous compounds. However, the role of various SULTs genes has not been reported in hepatocellular carcinoma (HCC). This study aims to analyze the expression and potential functional roles of SULTs genes in HCC and to identify the role of SULT2A1 in HCC stemness as well as the possible mechanism. We found that all of the 12 SULTs genes were differentially expressed in HCC. Moreover, clinicopathological features and survival rates were also investigated. Multivariate regression analysis showed that SULT2A1 and SULT1C2 could be used as independent prognostic factors in HCC. SULT1C4, SULT1E1, and SULT2A1 were significantly associated with immune infiltration. SULT2A1 deficiency in HCC promoted chemotherapy resistance and stemness maintenance. Mechanistically, silencing of SULT2A1 activated the AKT signaling pathway, on the one hand, promoted the expression of downstream stemness gene c-Myc, on the other hand, facilitated the NRF2 expression to reduce the accumulation of ROS, and jointly increased HCC stemness. Moreover, knockdown NR1I3 was involved in the transcriptional regulation of SULT2A1 in stemness maintenance. In addition, SULT2A1 knockdown HCC cells promoted the proliferation and activation of hepatic stellate cells (HSCs), thereby exerting a potential stroma remodeling effect. Our study revealed the expression and role of SULTs genes in HCC and identified the contribution of SULT2A1 to the initiation and progression of HCC.

Modulating intestinal health: Impact of chitooligosaccharide molecular weight on suppressing RAGE expression and inflammatory response in methylglyoxal-induced advanced glycation end-products

The accumulation of methylglyoxal (MGO) produced in high-temperature processed foods and excessive production in the body contributes to intestinal barrier dysfunction. In this study, we investigated the effects of chitooligosaccharides (COSs) of different molecular weights (<1 kDa, 1-3 kDa, 3-5 kDa, 5-10 kDa, and >10 kDa) on MGO-induced intestinal barrier dysfunction. We investigated the effect of COSs on inhibiting intracellular MGO accumulation/MGO-derived AGEs production and regulating the receptor for AGE (RAGE)-mediated downstream protein expression, including proteins related to apoptosis and inflammation, intestinal barrier integrity, and paracellular permeability. Pretreatment with COSs ameliorated MGO-induced increased RAGE protein expression, activation of apoptotic cascade/inflammatory response, loss of intestinal epithelial barrier integrity, and increased paracellular permeability, ameliorating intestinal dysfunction through MGO scavenging. 1-3 kDa COSs most effectively ameliorated MGO-induced intestinal dysfunction. Our results suggest the potential of COSs in improving intestinal health by ameliorating intestinal barrier dysfunction by acting as an MGO scavenger and highlighting the need for the optimization of the molecular weight of COSs to optimize its protective effects.

Butyrate increases methylglyoxal production through regulation of the JAK2/Stat3/Nrf2/Glo1 pathway in castration‑resistant prostate cancer cells

Cancer cells are characterized by increased glycolysis, known as the Warburg effect, which leads to increased production of cytotoxic methylglyoxal (MGO) and apoptotic cell death. Cancer cells often activate the protective nuclear factor erythroid 2‑related factor2 (Nrf2)/glyoxalase1 (Glo1) system to detoxify MGO. The effects of sodium butyrate (NaB), a product of gut microbiota, on Nrf2/Glos/MGO pathway and the underlying mechanisms in prostate cancer (PCa) cells were investigated in the present study. Treatment with NaB induced the cell death and reduced the proliferation of PCa cells (DU145 and LNCap). Moreover, the protein kinase RNA-like endoplasmic reticulum kinase/Nrf2/Glo1 pathway was greatly inhibited by NaB, thereby accumulating MGO-derived adduct hydroimidazolone (MG-H1). In response to a high amount of MGO, the expression of Nrf2 and Glo1 was attenuated, coinciding with an increased cellular death. NaB also markedly inhibited the Janus kinase 2 (JAK2)/Signal transducer and activator of transcription 3 (Stat3) pathway. Conversely, co‑treatment with Colivelin, a Stat3 activator, significantly reversed the effects of NaB on Glo1 expression, MG-H1 production, and the cell migration and viability. As expected, overexpression of Stat3 or Glo1 reduced NaB‑induced cell death. The activation of calcium/calmodulin dependent protein kinase II gamma and reactive oxygen species production also contributed to the anticancer effect of NaB. The present study, for the first time, demonstrated that NaB greatly increases MGO production through suppression of the JAK2/Stat3/Nrf2/Glo1 pathway in DU145 cells, a cell line mimicking castration‑resistant PCa (CRPC), suggesting that NaB may be a potential agent for PCa therapy.

Mechanical stress induced mitochondrial dysfunction in cardiovascular diseases: Novel mechanisms and therapeutic targets

Cardiovascular diseases (CVDs) are the leading cause of mortality worldwide. Others and our studies have shown that mechanical stresses (forces) including shear stress and cyclic stretch, occur in various pathological conditions, play significant roles in the development and progression of CVDs. Mitochondria regulate the physiological processes of cardiac and vascular cells mainly through adenosine triphosphate (ATP) production, calcium flux and redox control while promote cell death through electron transport complex (ETC) related cellular stress response. Mounting evidence reveal that mechanical stress-induced mitochondrial dysfunction plays a vital role in the pathogenesis of many CVDs including heart failure and atherosclerosis. This review summarized mitochondrial functions in cardiovascular system under physiological mechanical stress and mitochondrial dysfunction under pathological mechanical stress in CVDs (graphical abstract). The study of mitochondrial dysfunction under mechanical stress can further our understanding of the underlying mechanisms, identify potential therapeutic targets, and aid the development of novel treatments of CVDs.

Genistein Prevents Apoptosis and Oxidative Stress Induced by Methylglyoxal in Endothelial Cells

Glycolytic overload promotes accumulation of the highly reactive dicarbonyl compounds, resulting in harmful conditions called dicarbonyl stress. Methylglyoxal (MG) is a highly reactive dicarbonyl species and its accumulation plays a crucial pathophysiological role in diabetes and its vascular complications. MG cytotoxicity is mediated by reactive oxygen species (ROS) generation, a key event underlying the intracellular signaling pathways leading to inflammation and apoptosis. The identification of compounds able to inhibit ROS signaling pathways and counteract the MG-induced toxicity is a crucial step for developing new therapeutic strategies in the treatment of diabetic vascular complications. In this study, the effect of genistein, a natural soybean isoflavone, has been evaluated on MG-induced cytotoxicity in human endothelial cells. Our results show that genistein is able to counteract the MG-induced apoptosis by restraining ROS production, thus inhibiting the MAPK signaling pathways and caspase-3 activation. These findings identify a beneficial role for genistein, providing new insights for its potential clinical applications in preserving endothelial function in diabetic vascular complications.

Metformin switches cell death modes to soothe the apical periodontitis via ZBP1

Apical periodontitis (AP) is a disease caused by pathogenic microorganisms and featured with the degradation of periapical hard tissue. Our recent research showed the crucial role of Z-DNA binding protein 1 (ZBP1)-mediated necroptosis and apoptosis in the pathogenesis of AP. However, the specific regulatory mechanisms of ZBP1 in AP are not fully elucidated. It was found that metformin has a regulatory role in cell necroptosis and apoptosis. But whether and how metformin regulates necroptosis and apoptosis through the ZBP1 in the context of AP remains unknown. This study provided evidence that lipopolysaccharide (LPS) promotes the synthesis of left-handed Z-nucleic acids (Z-NA), which in turn activates ZBP1. Knockout of Zbp1 by CRISPR/Cas9 technology significantly reduced LPS-induced necroptosis and apoptosis in vitro. By using Zbp1-knockout mice, periapical bone destruction was alleviated. Moreover, type I interferon induced the expression of interferon-stimulated genes (ISGs), which serve as a major source of Z-NA. In addition, the RNA-editing enzyme Adenosine Deaminase RNA specific 1 (ADAR1) prevented the accumulation of endogenous Z-NA. Meanwhile, metformin suppressed the ZBP1-mediated necroptosis by inhibiting the expression of ZBP1 and the accumulation of ISGs. Metformin also promoted mitochondrial apoptosis, which is critical for the elimination of intracellular bacterial infection. The enhanced apoptosis further promoted the healing of infected apical bone tissues. In summary, these results demonstrated that the recognition of Z-NA by ZBP1 plays an important role in AP pathogenesis. Metformin suppressed ZBP1-mediated necroptosis and promoted apoptosis, thereby contributing to the soothing of inflammation and bone healing in AP.

Natural diterpenoid EKO activates deubiqutinase ATXN3 to preserve vascular endothelial integrity and alleviate diabetic retinopathy through c-fos/focal adhesion axis

Diabetic retinopathy (DR) is one of the most prevalent severe diabetic microvascular complications caused by hyperglycemia. Deciphering the underlying mechanism of vascular injury and finding ways to alleviate hyperglycemia induced microvascular complications is of great necessity. In this study, we identified that a compound ent-9α-hydroxy-15-oxo-16-kauren-19-oic acid (EKO), the diterpenoid isolated and purified from Pteris semipinnata L., exhibited good protective roles against vascular endothelial injury associated with diabetic retinopathy in vitro and in vivo. To further uncover the underlying mechanism, we used unbiased transcriptome sequencing analysis and showed substantial impairment in the focal adhesion pathway upon high glucose and IL-1β stimulation. EKO could effectively improve endothelial focal adhesion pathway by enhancing the expression of two focal adhesion proteins Vinculin and ITGA11. We found that c-fos protein was involved in regulating the expression of Vinculin and ITGA11, a transcription factor component that was downregulated by high glucose and IL-1β stimulation and recovered by EKO. Mechanically, EKO facilitated the binding of deubiquitylation enzyme ATXN3 to c-fos protein and promoted its deubiquitylation, thereby elevating its protein level to enhance the expression of Vinculin and ITGA11. Besides, EKO effectively suppressed ROS production and restored mitochondrial function. In vivo studies, we confirmed EKO could alleviate some of the indicators of diabetic mice. In addition, protein levels of ATXN3 and focal adhesion Vinculin molecule were also verified in vivo. Collectively, our findings addressed the endothelial protective role of natural diterpenoid EKO, with emphasize of mechanism on ATXN3/c-fos/focal adhesion signaling pathway as well as oxygen stress suppression, implicating its therapeutic potential in alleviating vascular endothelium injury and diabetic retinopathy.

Polystyrene nanoplastics-induced lung apoptosis and ferroptosis via ROS-dependent endoplasmic reticulum stress

It has been shown that exposure to nanoplastics (MNPs) through inhalation can induce pulmonary toxicity, but the toxicological mechanism of MNPs on the respiratory system remains unclear. Therefore, we explored the toxicological mechanism of exposure to polystyrene nanoplastics (PS-NPs) (0.05, 0.15, 0.2 mg/mL) on BEAS-2B cells. Results revealed that PS-NPs induce oxidative stress, increased apoptosis rate measured by flow cytometry, the key ferroptosis protein (GPX4 and FTH1) reduction, increased iron content, mitochondrial alterations, and increased malondialdehyde (MDA) level. Besides, consistent results were observed in mice exposed to PS-NPs (5 mg/kg/2d, 10 mg/kg/2d). Thus, we proved that PS-NPs induced cell death and lung damage through apoptosis and ferroptosis. In terms of mechanism, the elevation of the endoplasmic reticulum (ER) stress protein expression (IRE1α, PERK, XBP1S, and CHOP) revealed that PS-NPs induce lung damage by activating the two main ER stress pathways. Furthermore, the toxicological effects of PS-NPs observed in this study are attenuated by the ROS inhibitor N-acetylcysteine (NAC). Collectively, NPs-induced apoptosis and ferroptosis are attenuated by NAC via inhibiting the ROS-dependent ER stress in vitro and in vivo. This improves our understanding of the mechanism by which PS-NPs exposure leads to pulmonary injury and the potential protective effects of NAC.

Tom70-regulated mitochondrial biogenesis via TFAM improves hypoxia-induced dysfunction of pulmonary vascular endothelial cells and alleviates hypoxic pulmonary hypertension

BACKGROUND

Hypoxic pulmonary hypertension (HPH) is a common type of pulmonary hypertension and characterized by pulmonary vascular remodeling and constriction. A large number of studies have shown that pulmonary vascular endothelial cells (PVECs) dysfunction plays an important role in the initiation and development stages of HPH, but the mechanism of PVECs dysfunction after hypoxia remains unclear. In this study, we explored the exact mechanism of PVECs dysfunction after hypoxia.

METHODS

In vitro, we used primary cultured PVECs hypoxia model to mimic HPH injury. We detected the expressions of mitochondrial biogenesis markers, mitochondrial transcription factor A (TFAM) level inside mitochondria, mitochondrial quantity and function, and the components expressions of translocase of outer mitochondrial membrane (TOM) at 24 h after hypoxia. To explore the effects of Tom70 on mitochondrial biogenesis and functions of PVECs after hypoxia, Tom70 overexpression adenovirus was constructed, and the expressions of mitochondrial biogenesis markers, TFAM level inside mitochondria, mitochondrial quantity and function, and the functions of PVECs were detected. And in vivo, we used cre-dependent overexpression adenovirus of Tom70 in the Cdh5-CreERT2 mouse model of HPH to verify the role of upregulating PVECs Tom70 in improving HPH.

RESULTS

Hypoxia obviously increased the expressions of mitochondrial biogenesis markers for PGC-1α, NRF-1 and TFAM, but reduced the content of TFAM in mitochondria and the quantity and functions of mitochondria. In addition, only Tom70 expression among the TOM components was significantly decreased after hypoxia, and up-regulation of Tom70 significantly increased the content of TFAM in mitochondria of PVECs by transporting TFAM into mitochondria after hypoxia, enhanced the quantity and functions of mitochondria, improved the functions of PVECs, and ultimately alleviated HPH.

CONCLUSION

The findings of present study demonstrated that hypoxia induced the decreased expression of Tom70 in PVECs, reduced the mitochondrial biogenesis-associated TFAM protein transporting into mitochondria, inhibited mitochondrial biogenesis, caused PVECs injury, and prompted the formation of HPH. However, up-regulation of Tom70 abolished the hypoxia-induced injurious effects on PVECs and alleviated HPH.

Evaluating the protective effect of metformin against diclofenac-induced oxidative stress and hepatic damage: In vitro and in vivo studies

Diclofenac (DIC) is one of the most commonly prescribed non-steroidal anti-inflammatory drugs and has been shown to cause oxidative stress and liver injury. The current study investigated protective effects of metformin against DIC-induced hepatic toxicity in both in vitro and in vivo models. For the in vitro study, HepG2 cells were exposed to DIC in the presence or absence of metformin. The effect of metformin on cell viability was evaluated by MTT assay. Oxidative stress parameters (malondialdehyde (MDA), total thiol molecules (TTM), and total antioxidant capacity (TAC)) were assessed. For the in vivo study, thirty-six male Wistar rats were randomly divided into 6 groups. These groups were normal saline, metformin (200 mg/kg), DIC (50 mg/kg/day), DIC + metformin (50, 100, and 200 mg/kg/day). Histopathological studies and serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), albumin, direct and total bilirubin were measured. Also, oxidative stress parameters were assessed in liver tissue. Furthermore, expression of glutathione peroxidase (GPX)-1, -3, and -4, catalase (CAT), superoxide dismutase (SOD)-1, and -3 was examined using the real-time PCR method in hepatic tissue. In the in vitro study, metformin significantly prevented DIC-induced loss in cell viability in HepG2 cells. Metformin markedly reduced DIC-induced elevation of MDA levels and increased the TAC and TTM levels. In the in vivo study, metformin significantly prevented DIC-induced changes in hematological and histological markers. Administration of metformin significantly improved oxidative stress parameters in liver tissue. In addition, metformin increased the expression of antioxidant enzymes. Our results suggest that metformin exerts a significant protective effect against DIC-induced hepatic toxicity.

Methylglyoxal-induced neurotoxic effects in primary neuronal-like cells transdifferentiated from human mesenchymal stem cells: Impact of low concentrations

In the last decades, advanced glycation end-products (AGEs) have aroused the interest of the scientific community due to the increasing evidence of their involvement in many pathophysiological processes including various neurological disorders and cognitive decline age related. Methylglyoxal (MG) is one of the reactive dicarbonyl precursors of AGEs, mainly generated as a by-product of glycolysis, whose accumulation induces neurotoxicity. In our study, MG cytotoxicity was evaluated employing a human stem cell-derived model, namely, neuron-like cells (hNLCs) transdifferentiated from mesenchymal stem/stromal cells, which served as a source of human based species-specific "healthy" cells. MG increased ROS production and induced the first characteristic apoptotic hallmarks already at low concentrations (≥10 μM), decreased the cell growth (≥5-10 μM) and viability (≥25 μM), altered Glo-1 and Glo-2 enzymes (≥25 μM), and markedly affected the neuronal markers MAP-2 and NSE causing their loss at low MG concentrations (≥10 μM). Morphological alterations started at 100 μM, followed by even more marked effects and cell death after few hours (5 h) from 200 μM MG addition. Substantially, most effects occurred as low as 10 μM, concentration much lower than that reported from previous observations using different in vitro cell-based models (e.g., human neuroblastoma cell lines, primary animal cells, and human iPSCs). Remarkably, this low effective concentration approaches the level range measured in biological samples of pathological subjects. The use of a suitable cellular model, that is, human primary neurons, can provide an additional valuable tool, mimicking better the physiological and biochemical properties of brain cells, in order to evaluate the mechanistic basis of molecular and cellular alterations in CNS.

Hyperoside Prevents Aβ42-Induced Neurotoxicity in PC12 Cells and Caenorhabditis elegans

Traditional Chinese medicines such as hyperoside-rich Acanthopanax senticosus and Crataegus pinnatifida have been confirmed to exhibit anti-oxidative stress properties. Hyperoside, the main ingredient of numerous antioxidant herbs, may have the ability to postpone the onset of neurodegenerative diseases. This study investigates the possible therapeutic mechanism of hyperoside as a natural antioxidant against Alzheimer's disease (AD) in Caenorhabditis elegans and PC12 cells. Specifically, hyperoside reduced reactive oxygen species (ROS) level and Aβ42-induced neurotoxicity in C. elegans worms. Meanwhile, hyperoside reduced ROS production and increased mitochondrial membrane potentialin Aβ42-induced PC12 cells, which possibly due to the increase of antioxidant enzymes activity and the diminution of malondialdehyde levels. Hoechst 33,342 staining and flow cytometry analysis results suggested that hyperoside reverses cell apoptosis. Network pharmacology predicts potentially relevant hyperoside targets and pathways in AD therapy. As anticipated, hyperoside reversed Aβ42-stimulated downregulation of the PI3K/Akt/Nrf2/HO-1. The PI3K inhibitor LY294002 partially abolished the protective capability of hyperoside. The results of molecular docking further indicated that the PI3K/Akt pathways may be involved in the protection of Aβ42-induced PC12 cells by hyperoside treatment. The study provides theoretical information for research and development of hyperoside as an antioxidant dietary supplement.

White adipose tissue-derived small extracellular vesicles: A new potential therapeutic reagent for accelerating diabetic wound healing

Small extracellular vesicles (sEVs) from adipose-derived stem cells (ADSCs) have gained great attention and have been widely used in cell-free therapies for treating diabetic non-healing wounds in recent years. However, further clinical application of ADSC-sEVs have been limited due to their unsolvable defects, including cumbersome extraction procedure, high cost, low yield, etc. Thus, we urgently need to find one therapeutic reagent that could not only accelerate diabetic wound healing as ADSC-sEVs but also overcome these shortcomings. As the extraction process of adipose tissue-derived sEVs (AT-sEVs) is quite simple and labor saving, we put our focus on the efficiencies of white adipose tissue-derived sEVs (WAT-sEVs) and brown adipose tissue-derived sEVs (BAT-sEVs) in diabetic wound repair. After successfully isolating WAT-sEVs and BAT-sEVs by ultracentrifugation, we thoroughly characterized them and compared their diabetic wound healing capabilities both in vitro and in vivo. According to our study, AT-sEVs possess similar competence in diabetic wound healing as compared with ADSC-sEVs. While the effect of BAT-sEVs is not as stable as WAT-sEVs and ADSC-sEVs, the repair efficiency is also slightly lower than the other two sEVs in some cases. In summary, we are the first to discover that WAT-sEVs show great potential in diabetic wound repair. With advantages that are specific to tissue-derived sEVs (Ti-sEVs) such as time- and cost-saving, high-yield, and simple isolation procedure, we believe WAT-sEVs could serve as a novel reliable cell-free therapy for clinical diabetic wound treatment.

Methylglyoxal in Cardiometabolic Disorders: Routes Leading to Pathology Counterbalanced by Treatment Strategies

Methylglyoxal (MGO) is the major compound belonging to reactive carbonyl species (RCS) responsible for the generation of advanced glycation end products (AGEs). Its upregulation, followed by deleterious effects at the cellular and systemic levels, is associated with metabolic disturbances (hyperglycemia/hyperinsulinemia/insulin resistance/hyperlipidemia/inflammatory processes/carbonyl stress/oxidative stress/hypoxia). Therefore, it is implicated in a variety of disorders, including metabolic syndrome, diabetes mellitus, and cardiovascular diseases. In this review, an interplay between pathways leading to MGO generation and scavenging is addressed in regard to this system's impairment in pathology. The issues associated with mechanistic MGO involvement in pathological processes, as well as the discussion on its possible causative role in cardiometabolic diseases, are enclosed. Finally, the main strategies aimed at MGO and its AGEs downregulation with respect to cardiometabolic disorders treatment are addressed. Potential glycation inhibitors and MGO scavengers are discussed, as well as the mechanisms of their action.

Novel Fluorometric Assay of Antiglycation Activity Based on Methylglyoxal-Induced Protein Carbonylation

Advanced glycation end products (AGEs), which can have multiple structures, are formed at the sites where the carbonyl groups of reducing sugars bind to the free amino groups of proteins through the Maillard reaction. Some AGE structures exhibit fluorescence, and this fluorescence has been used to measure the formation and quantitative changes in carbonylated proteins. Recently, fluorescent AGEs have also been used as an index for the evaluation of compounds that inhibit protein glycation. However, the systems used to generate fluorescent AGEs from the reaction of reducing sugars and proteins used for the evaluation of antiglycation activity have not been determined through appropriate research; thus, problems remain regarding sensitivity, quantification, and precision. In the present study, using methylglyoxal (MGO), a reactive carbonyl compound to induce glycation, a comparative analysis of the mechanisms of formation of fluorescent substances from several types of proteins was conducted. The analysis identified hen egg lysozyme (HEL) as a protein that produces stronger fluorescent AGEs faster in the Maillard reaction with MGO. It was also found that the AGE structure produced in MGO-induced in HEL was argpyrimidine. By optimizing the reaction system, we developed a new evaluation method for compounds with antiglycation activity and established an efficient evaluation method (HEL-MGO assay) with greater sensitivity and accuracy than the conventional method, which requires high concentrations of bovine serum albumin and glucose. Furthermore, when compounds known to inhibit glycation were evaluated using this method, their antiglycation activities were clearly and significantly measured, demonstrating the practicality of this method.

Rutaecarpine Mitigates Cognitive Impairment by Balancing Mitochondrial Function Through Activation of the AMPK/PGC1α Pathway

Mitochondrial dysfunction plays a fundamental role in the pathogenesis of cognitive deficit. Rutaecarpine (Rut) is a natural alkaloid with anti-inflammatory and antioxidant properties. This study explored whether Rut treatment could enhance cognitive function by improving mitochondrial function and examined the potential mechanisms underlying this ameliorative effect. We used the Morris water maze and Y-maze tests to evaluate the behavioral effects of Rut in a mouse model of cognitive impairment induced by subcutaneous injection of D-galactose (D-gal). Furthermore, we assessed the effects of Rut on mitochondrial function using cell viability assays, flow cytometry, western blotting, biochemical analysis, and immunochemical techniques in vivo and in vitro. The results indicated Rut treatment attenuated cognitive deficits and mitochondrial dysfunction in the mouse model. Similarly, it maintained the balance of mitochondrial dynamics in neurocytes and reduced oxidative stress and mitochondrial apoptosis in the HT22 cell model. Moreover, we found that these protective effects were dependent on the activation of the AMP-activated protein kinase/proliferator-activated receptor gamma coactivator 1-alpha (AMPK/PGC1α) signaling pathway. Our data indicate that Rut treatment are sensitive to reversal cognitive deficits and mitochondrial dysfunction induced by D-gal; this suggests that Rut is a promising mitochondria-targeted therapeutic agent for treating cognitive impairment.

Effect of Metformin on the Functional and Electrophysiological Recovery of Crush Injury-Induced Facial Nerve Paralysis in Diabetic Rats

The impact of metformin on the rat facial nerve following crush injury has only occasionally been documented to date. The purpose of the current investigation was to use functional and electrophysiological evaluations to investigate the effects of metformin administration on recovery following crush injury to the rat facial nerve. The rats were randomly divided into four groups: the nonDM/PBS group (n = 4), the nonDM/metformin group (n = 4), the DM/PBS group (n = 4), and the DM/metformin group (n = 4). Diabetes was generated by an intraperitoneal injection of streptozotocin. Facial nerve paralysis was induced by a crush injury 7 days after diabetes induction. The blood glucose levels of the DM/PBS and DM/metformin groups were maintained at over 300 mg/dL, whereas the blood glucose levels of the nonDM/PBS and nonDM/metformin groups were maintained at less than 150 mg/dL. There was no significant difference between the two nonDM groups. In comparison to the PBS group, the metformin group's recurrence of vibrissa fibrillation occurred noticeably sooner over time. The nonDM/metformin group showed the highest recovery rate in the second, third, and fourth weeks post-crush, respectively. The threshold of action potential 4 weeks after crush injury showed that the nonDM/metformin group had a significantly lower mean threshold of MAP compared to other groups. The short-term effect of metformin on the recovery of facial nerve blood flow (FNBF) was significantly increased compared to the DM/PBS group. However, there was no significant difference in FNBF between the nonDM/metformin and nonDM/PBS groups. A diabetic condition promoted a delay in FN regeneration. Metformin is able to accelerate functional recovery in diabetic or nondiabetic FN-injured rats. Further studies using a morphometric or molecular approach are planned to understand the pharmacologic mechanism of metformin.

Association of low-level lead exposure with all-cause and cardiovascular disease mortality in US adults with hypertension: evidence from the National Health and Nutrition Examination Survey 2003-2010

BACKGROUND

To explore the association of low-level lead exposure with all-cause mortality and cardiovascular disease (CVD) mortality among hypertensive patients.

METHODS

This cohort study enrolled 6453 adults with hypertension from the National Health and Nutrition Examination Survey 2003-2010 and followed mortality information through December 31, 2019. The baseline population were divided into four groups based on quartiles of blood lead levels (Q1: < 1.2 μg/dL, Q2: 1.2-1.6 μg/dL, Q3: 1.7-2.4 μg/dL, Q4: 2.5-4.9 μg/dL). The correlation of blood lead levels to mortality was investigated by Kaplan-Meier survival curves, restricted cubic spline (RCS), proportional hazard regression model, and subgroup analysis.

RESULTS

During a median follow-up period of 136 (interquartile range 113, 164) months, a total of 1943 (30.1%) deaths were documented, among which 553 (28.5%) were due to CVD. Blood lead showed a linear dose-response relationship with all-cause and CVD mortality. After adequate adjusting for confounders, the risk of all-cause death rose by 23% for each unit increase in continuous variable blood lead (hazard ratio (HR): 1.23; 95% confidence interval (CI):1.16-1.30). When blood lead was a quartile group variable, participants in the Q 4 group had a 73% higher risk of death than those in the Q 1 group (HR:1.73; 95% CI: 1.43-2.10; P for trend < 0.001). The association for CVD mortality was analogous. The concordant results were achieved in the subgroup analysis.

CONCLUSION

Elevated blood lead levels were strongly associated with an increased all-cause and CVD mortality in adults with hypertension, even at the reference range of blood lead.

Salidroside alleviates acetaminophen-induced hepatotoxicity via Sirt1-mediated activation of Akt/Nrf2 pathway and suppression of NF-κB/NLRP3 inflammasome axis

Acetaminophen (APAP) overdose-induced hepatotoxicity is the most common cause of drug-induced liver injury worldwide, which is significantly linked to oxidative stress and sterile inflammation. Salidroside is the main active component extracted from Rhodiola rosea L., with anti-oxidative and anti-inflammatory activities. Herein, we investigated the protective effects of salidroside on APAP-induced liver injury and its underlying mechanisms. Pretreatment with salidroside reversed the impacts of APAP on cell viability, LDH release, and cell apoptosis in L02 cells. Moreover, the phenomena of ROS accumulation and MMP collapse caused by APAP were reverted by salidroside. Salidroside elevated the levels of nuclear Nrf2, HO-1, and NQO1. Using PI3k/Akt inhibitor LY294002 further confirmed that salidroside mediated the Nrf2 nuclear translocation through the Akt pathway. Pretreatment with Nrf2 siRNA or LY294002 markedly prevented the anti-apoptotic effect of salidroside. Additionally, salidroside reduced the levels of nuclear NF-κB, NLRP3, ASC, cleaved caspase-1, and mature IL-1β elevated by APAP. Moreover, salidroside pretreatment increased Sirt1 expression, whereas Sirt1 knock-down diminished the protective activities of salidroside, simultaneously reversing the up-regulation of the Akt/Nrf2 pathway and the down-regulation of NF-κB/NLRP3 inflammasome axis mediated by salidroside. We then used C57BL/6 mice to establish APAP-induced liver injury models and found that salidroside significantly alleviated liver injury. Furthermore, western blot analyses showed that salidroside promoted the Sirt1 expression, activated the Akt/Nrf2 pathway, and inhibited the NF-κB/NLRP3 inflammasome axis in APAP-treated mice. The findings of this study support a possible application of salidroside in the amelioration of APAP-induced hepatotoxicity.

Global Oxidative Status Is Linked to Calcific Aortic Stenosis: The Differences Due to Diabetes Mellitus and the Effects of Metformin

Calcific aortic stenosis (CAS) and type 2 diabetes mellitus (T2DM) are related and often concomitant pathologies, accompanied by common comorbidities such as hypertension or dyslipidemia. Oxidative stress is one of the mechanisms that trigger CAS, and it can drive the vascular complications in T2DM. Metformin can inhibit oxidative stress, yet its effects have not been studied in the context of CAS. Here, we assessed the global oxidative status in plasma from patients with CAS, both alone and with T2DM (and under treatment with metformin), using multimarker scores of systemic oxidative damage (OxyScore) and antioxidant defense (AntioxyScore). The OxyScore was determined by measuring carbonyls, oxidized LDL (oxLDL), 8-hydroxy-20-deoxyguanosine (8-OHdG), and xanthine oxidase (XOD) activity. In contrast, the AntioxyScore was determined through the catalase (CAT) and superoxide dismutase (SOD) activity, as well as the total antioxidant capacity (TAC). Patients with CAS displayed enhanced oxidative stress compared to control subjects, probably exceeding their antioxidant capacity. Interestingly, patients with CAS and T2DM displayed less oxidative stress, possibly due to the benefits of their pharmacological therapy (metformin). Thus, reducing oxidative stress or enhancing antioxidant capacity through specific therapies could be a good strategy to manage CAS, focusing on personalized medicine.

Umbelliferone protects against methylglyoxal-induced HUVECs dysfunction through suppression of apoptosis and oxidative stress

Methylglyoxal (MGO), a cytotoxic metabolite of glycolysis, can cause endothelial cells impairment, which is tightly associated with diabetic vascular complication. Umbelliferone, a derivative of coumarin, participates in various pharmacological activities. This study aimed to determine the effectiveness of umbelliferone in MGO-induced apoptosis and oxidative stress in endothelial cells. In this study, it has been indicated that umbelliferone inhibited MGO-induced human umbilical vein endothelial cells (HUVECs) cytotoxicity, apoptosis, Bax/Bcl-2 protein ratio, the activity of cleaved-caspase-3, and mitochondrial membrane potential loss. Furthermore, we found that umbelliferone inhibited MGO-induced activation of mitogen-activated protein kinases and nuclear factor-κB signaling pathways in HUVECs. In addition, umbelliferone could suppress oxidative stress, as evidenced by decrease of reactive oxygen species and malondialdehyde (MDA) generation, and increase of superoxide dismutase and glutathione peroxidase contents. Moreover, we found that umbelliferone can activate Nrf2/HO-1 signaling. Importantly, silencing of Nrf2 signaling clearly eliminated the anti-oxidative stress of umbelliferone, whereas umbelliferone pretreatment had no effect on Nrf2 overexpressing HUVECs. Altogether, this study suggested that umbelliferone pretreatment has a protective effect on MGO-induced endothelial cell dysfunction through inhibiting apoptosis and oxidative stress.

Alu antisense RNA ameliorates methylglyoxal-induced human lens epithelial cell apoptosis by enhancing antioxidant defense

AIM

To determine whether an antisense RNA corresponding to the human Alu transposable element (Aluas RNA) can protect human lens epithelial cells (HLECs) from methylglyoxal-induced apoptosis.

METHODS

Cell counting kit-8 (CCK-8) and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays were used to assess HLEC viability. HLEC viability/death was detected using a Calcein-AM/PI double staining kit; the annexin V-FITC method was used to detect HLEC apoptosis. The cytosolic reactive oxygen species (ROS) levels in HLECs were determined using a reactive species assay kit. The levels of malondialdehyde (MDA) and the antioxidant activities of total-superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) were assessed in HLECs using their respective kits. RT-qPCR and Western blotting were used to measure mRNA and protein expression levels of the genes.

RESULTS

Aluas RNA rescued methylglyoxal-induced apoptosis in HLECs and ameliorated both the methylglyoxal-induced decrease in Bcl-2 mRNA and the methylglyoxal-induced increase in Bax mRNA. In addition, Aluas RNA inhibited the methylglyoxal-induced increase in Alu sense RNA expression. Aluas RNA inhibited the production of ROS induced by methylglyoxal, restored T-SOD and GSH-Px activity, and moderated the increase in MDA content after treatment with methylglyoxal. Aluas RNA significantly restored the methylglyoxal-induced down-regulation of Nrf2 gene and antioxidant defense genes, including glutathione peroxidase, heme oxygenase 1, γ-glutamylcysteine synthetase and quinone oxidoreductase 1. Aluas RNA ameliorated methylglyoxal-induced increases of the mRNA and protein expression of Keap1 that is the negative regulator of Nrf2.

CONCLUSION

Aluas RNA reduces apoptosis induced by methylglyoxal by enhancing antioxidant defense.

Bisphenol A (BPA) induces apoptosis of mouse Leydig cells via oxidative stress

As one of the most frequently produced synthetic compounds worldwide, bisphenol A (BPA) has been widely used in many kinds of products such as appliances, housewares, and beverage cans. BPA has been shown to cause damage to male reproductive system; however, the potential mechanism remains to be investigated. In the present study, BPA exposure decreased the testis and epididymis coefficient, caused a disintegration of germinal epithelium, decreased the density and motility of sperm in the epididymis tissue, and increased the number of abnormal sperm morphology, which indicated that BPA exposure could cause damage to testis. BPA was also shown to induce apoptosis and oxidative stress in the testis tissue. The serum testosterone concentration was decreased in the BPA-treated group, suggesting that BPA could lead to Leydig cell damage. Subsequently, mouse TM3 cell, a kind of mouse Leydig cell line, was utilized to investigate the potential mechanism. Herein, we showed that BPA exposure could inhibit cell viability and induce apoptosis of TM3 cells. Furthermore, oxidative stress in the cells could also be induced by BPA, while the inhibition of oxidative stress by N-acetyl-L-cysteine (NAC), an oxidative stress scavenger, could reverse the inhibition of cell viability and induction of apoptosis by BPA exposure, indicating that oxidative stress was involved in BPA-induced apoptosis of TM3 cells. Finally, RNA-sequencing and real-time PCR were utilized to screen and validate the potential oxidative stress-related genes involving in BPA-induced apoptosis. We found that BPA exposure increased the mRNA levels of oxidative stress-related genes such as Lonp1, Klf4, Rack1, Egln1, Txn2, Msrb1, Atox1, Mtr, and Atp2a2, as well as decreased the mRNA level of Dhfr gene; while NAC could rescue the expression of these genes. Taken together, oxidative stress was involved in BPA-induced apoptosis of mouse Leydig cells.

Advanced glycation endproducts in diabetes-related macrovascular complications: focus on methylglyoxal

Diabetes is associated with vascular injury and the onset of macrovascular complications. Advanced glycation endproducts (AGEs) and the AGE precursor methylglyoxal (MGO) have been identified as key players in establishing the relationship between diabetes and vascular injury. While most research has focused on the link between AGEs and vascular injury, less is known about the effects of MGO on vasculature. In this review, we focus on the mechanisms linking AGEs and MGO to the development of atherosclerosis. AGEs and MGO are involved in many stages of atherosclerosis progression. However, more research is needed to determine the exact mechanisms underlying these effects. Nevertheless, AGEs and MGO could represent valid therapeutic targets for the macrovascular complications of diabetes.

Reduction of miR-133a-3p contributes to apoptosis and gasdermin E-mediated pyroptosis of keratinocytes in skin exposed to ultraviolet B radiation

Engagement of regulated cell death in keratinocytes plays a crucial role in the pathogenesis and development of skin disorders associated with UV radiation. However, it remains unclear how microRNAs (miRNAs) participate in the regulation of UV-caused keratinocyte death. In this study, we found that miR-133a-3p was decreased in the epidermis of UVB-challenged mice and UVB-irradiated keratinocyte cell line HaCaT cells. The intradermal injection of agomir miR-133a-3p ameliorated skin damage of UVB-challenged mice, especially epidermal necrosis. Meanwhile, the injection inhibited apoptosis indicator PARP cleavage and pyroptosis indicator GSDME cleavage in the epidermis. In UVB-challenged HaCaT cells, transfection of miR-133a-3p mimic or inhibitor alleviated or aggravated UVB-induced apoptosis and GSDME-mediated pyroptosis respectively. miR-133a-3p was also involved in the effects of metformin treatment on alleviating skin damage in UVB-challenged mice and on inhibiting apoptosis and GSDME-mediated pyroptosis in UVB-irradiated HaCaT cells. We confirmed that CYLD is a target gene of miR-133a-3p and participates in the protective effects of miR-133a-3p on inhibiting UVB-caused apoptosis and GSDME-mediated pyroptosis in keratinocytes. This study indicates a pivotal role for miR-133a-3p of keratinocytes in UVB-caused skin damage. Alleviating skin photodamage by restoring the decrease of miR-133a-3p can be considered a potential therapeutic approach.

Metformin Attenuates Hyperglycaemia-Stimulated Pro-Fibrotic Gene Expression in Adventitial Fibroblasts via Inhibition of Discoidin Domain Receptor 2

Molecular mechanisms underlying the diverse therapeutic effects of anti-diabetic metformin, beyond its anti-hyperglycaemic effects, remain largely unclear. Metformin is reported to reduce the long-term complications of diabetes, including cardiovascular fibrosis and remodelling. Our recent investigations show that Discoidin Domain Receptor 2 (DDR2), a Collagen receptor tyrosine kinase, has an obligate regulatory role in Collagen type I gene expression in cardiac and vascular adventitial fibroblasts, and that it may be a molecular link between arterial fibrosis and metabolic syndrome in rhesus monkeys. Using gene knockdown and overexpression approaches, the present study examined whether DDR2 is a target of metformin and whether, by targeting DDR2, it inhibits Fibronectin and Collagen type I expression in rat aortic adventitial fibroblasts exposed to hyperglycaemic conditions. Metformin was found to attenuate hyperglycaemia-induced increase in DDR2 mRNA and protein expression by inhibiting TGF-β1/SMAD2/3 signalling that mediates the stimulatory effect of hyperglycaemia on DDR2 expression. Metformin also inhibited DDR2-dependent expression of Fibronectin and Collagen type I, indicating that it regulates these matrix proteins via DDR2 inhibition. The findings identify DDR2, a mediator of cardiovascular remodelling, as a molecular target of metformin, thereby uncovering the molecular basis of its protective role in vascular fibrosis and possibly cardiac fibrosis associated with diabetic cardiomyopathy.

Crocin attenuates endoplasmic reticulum stress in methylglyoxal-induced diabetic nephropathy in male mice: MicroRNAs alterations and glyoxalase 1-Nrf2 signaling pathways

OBJECTIVES

Accumulation of methylglyoxal (MGO) occurs in diabetes. MicroRNA-204 is an important intracellular marker in the diagnosis of endoplasmic reticulum stress. Crocin (Crn) has beneficial effects for diabetes, but the effect of Crn on MGO-induced diabetic nephropathy has not been investigated. The current research evaluated the effects of Crn and metformin (MET) on diabetic nephropathy induced by MGO in male mice.

MATERIALS AND METHODS

In this experimental study, 70 male NMRI mice were randomly divided into 7 groups: control, MGO (600 mg/Kg/d), MGO+Crn (15, 30, and 60 mg/kg/d), MGO+MET (150 mg/kg/d), and Crn60 (60 mg/kg/d). Methylglyoxal was gavaged for four weeks. After proving hyperglycemia, Cr and MET were administered orally in the last two weeks. Biochemical and antioxidant evaluations, microRNA expression, and histological evaluation were assessed.

RESULTS

The fasting blood glucose, urine albumin, blood urea nitrogen, plasma creatinine, malondialdehyde, Nrf2, miR-204, and miR-192 expression increased in the MGO group. These variables decreased in Crn-treated animals. The decreased levels of superoxide dismutase, catalase, glyoxalase 1, Glutathione, and miR-29a expression in the MGO group improved in the diabetic-treated mice. Histological alterations such as red blood cell accumulation, inflammation, glomerulus diameter changes, and proximal cell damage were also observed.

CONCLUSION

Our study indicated that Crn and MET attenuated renal damage by inhibiting endoplasmic reticulum stress.

Metformin Attenuates Ferroptosis and Promotes Functional Recovery of Spinal Cord Injury

BACKGROUND

Ferroptosis is involved in traumatic spinal cord injury (SCI), and its inhibition may improve functional recovery after traumatic SCI. This study investigated whether metformin (Met) can have a neuroprotective effect in SCI repair by inhibiting ferroptosis.

METHODS

We assessed functional change to determine the long-term effects after intraperitoneal injection of Met in SCI rats with the Basso-Beattie-Bresnahan locomotor rating scale. Malondialdehyde level and relative expression of key proteins, inflammatory cytokines, and nuclear factor E2-related factor 2 signalling molecules were determined in SCI rats and PC12 cells exposed to FeCl₃ solution.

RESULTS

Met treatment decreased the contents of malondialdehyde, regulated the levels of inflammatory factors, activated the nuclear factor E2-related factor 2 signalling pathway, and improved long-term outcomes by ameliorating SCI-induced locomotor deficits. In vitro studies further confirmed the beneficial and antiferroptotic actions of Met partly through activation of nuclear factor E2-related factor 2 signalling.

CONCLUSION

Met can have a neuroprotective effect on SCI repair partly through antiferroptotic effects.

Is metformin a possible treatment for diabetic neuropathy?

Metformin is a hypoglycemic drug widely used in the treatment of type 2 diabetes. It has been proven to have analgesic and neuroprotective effects. Metformin can reverse pain in rodents, such as diabetic neuropathic pain, neuropathic pain caused by chemotherapy drugs, inflammatory pain and pain caused by surgical incision. In clinical use, however, metformin is associated with reduced plasma vitamin B12 levels, which can further neuropathy. In rodent diabetes models, metformin plays a neuroprotective and analgesic role by activating adenosine monophosphate-activated protein kinase, clearing methylgloxal, reducing insulin resistance, and neuroinflammation. This paper also summarized the neurological adverse reactions of metformin in diabetic patients. In addition, whether metformin has sexual dimorphism needs further study.

Nordihydroguaiaretic acid inhibits glyoxalase I, and causes the accumulation of methylglyoxal followed by cell-growth inhibition

BACKGROUND

Methylglyoxal (MGO) is a known toxic byproduct of glycolysis, with MGO-induced cytotoxicity believed to contribute to the pathogenesis of several diseases. Glyoxalase I (GLO1) is a key enzyme for eliminating MGO in mammalian cells, therefore, compounds affecting GLO1 activity are potential therapeutic agents for MGO-induced disorders. Previously, we found nordihydroguaiaretic acid (NDGA) as a potent GLO1 inhibitor.

METHODS

The inhibitory characteristics of NDGA were determined spectrophotometrically with recombinant GLO1. NDGA-induced growth-inhibition and accumulation of MGO-derived advanced glycation end products (AGEs) were examined in EA.hy926 cells.

RESULTS

NDGA showed significant inhibition of GLO1 enzymatic activity in a dose-dependent manner. Its K_i value was estimated to be 146-fold lower than that of myricetin, a known GLO1 inhibitor. The co-addition of MGO with NDGA to the cells resulted in significant growth inhibition, suggesting that MGO accumulation, sufficient to affect cell growth, was caused by NDGA inhibiting GLO1. These findings were supported by the observations that the addition of aminoguanidine, a typical MGO scavenger, significantly reversed cell-growth inhibition by co-addition of MGO with NDGA, and that an increase in intracellular MGO-derived AGEs was observed during incubation with the co-addition of MGO with NDGA.

CONCLUSION

NDGA was found to be a novel and potent inhibitor of GLO1. The co-addition of NDGA with MGO to the cells resulted in increased intracellular MGO accumulation followed by enhanced cell-growth inhibition.

Vaccarin alleviates endothelial inflammatory injury in diabetes by mediating miR-570-3p/HDAC1 pathway

Vaccarin is a flavonoid glycoside, which has a variety of pharmacological properties and plays a protective role in diabetes and its complications, but its mechanism is unclear. In this study, we aim to investigate whether histone deacetylase 1(HDAC1), a gene that plays a pivotal role in regulating eukaryotic gene expression, is the target of miR-570-3p in diabetic vascular endothelium, and the potential molecular mechanism of vaccarin regulating endothelial inflammatory injury through miR-570-3p/HDAC1 pathway. The HFD and streptozotocin (STZ) induced diabetes mice model, a classical type 2 diabetic model, was established. The aorta of diabetic mice displayed a decrease of miR-570-3p, the elevation of HDAC1, and inflammatory injury, which were alleviated by vaccarin. Next, we employed the role of vaccarin in regulating endothelial cells miR-570-3p and HDAC1 under hyperglycemia conditions in vitro. We discovered that overexpression of HDAC1 counteracted the inhibitory effect of vaccarin on inflammatory injury in human umbilical vein endothelial cells (HUVECs). Manipulation of miRNA levels in HUVECs was achieved by transfecting cells with miR-570-3p mimic and inhibitor. Overexpression of miR-570-3p could decrease the expression of downstream components of HDAC1 including TNF-α, IL-1β, and malondialdehyde, while increasing GSH-Px activity in HUVECs under hyperglycemic conditions. Nevertheless, such phenomenon was completely reversed by miR-570-3p inhibitor, and administration of miR-570-3p inhibitor could block the inhibition of vaccarin on HDAC1 and inflammatory injury. Luciferase reporter assay confirmed the 3′- UTR of the HDAC1 gene was a direct target of miR-570-3p. In summary, our findings suggest that vaccarin alleviates endothelial inflammatory injury in diabetes by mediating miR-570-3p/HDAC1 pathway. Our study provides a new pathogenic link between deregulation of miRNA expression in the vascular endothelium of diabetes and inflammatory injury and provides new ideas, insights, and choices for the scope of application and medicinal value of vaccarin and some potential biomarkers or targets in diabetic endothelial dysfunction and vascular complications.

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

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

Dicarbonyl-Dependent Modification of LDL as a Key Factor of Endothelial Dysfunction and Atherosclerotic Vascular Wall Damage

The review presents evidence that the main damage to the vascular wall occurs not from the action of “oxidized” LDL, which contain hydroperoxy acyls in the phospholipids located in their outer layer, but from the action of LDL particles whose apoprotein B-100 is chemically modified with low molecular weight dicarbonyls, such as malondialdehyde, glyoxal, and methylglyoxal. It has been argued that dicarbonyl-modified LDL, which have the highest cholesterol content, are particularly “atherogenic”. High levels of dicarbonyl-modified LDL have been found to be characteristic of some mutations of apoprotein B-100. Based on the reviewed data, we hypothesized a common molecular mechanism underlying vascular wall damage in atherosclerosis and diabetes mellitus. The important role of oxidatively modified LDL in endothelial dysfunction is discussed in detail. In particular, the role of the interaction of the endothelial receptor LOX-1 with oxidatively modified LDL, which leads to the expression of NADPH oxidase, which in turn generates superoxide anion radical, is discussed. Such hyperproduction of ROS can cause destruction of the glycocalyx, a protective layer of endotheliocytes, and stimulation of apoptosis in these cells. On the whole, the accumulated evidence suggests that carbonyl modification of apoprotein B-100 of LDL is a key factor responsible for vascular wall damage leading to atherogenesis and endothelial dysfunction. Possible ways of pharmacological correction of free radical processes in atherogenesis and diabetogenesis are also discussed.

Anti-Diabetic Therapy, Heart Failure and Oxidative Stress: An Update

Diabetes mellitus (DM) and heart failure (HF) are two chronic disorders that affect millions worldwide. Hyperglycemia can induce excessive generation of highly reactive free radicals that promote oxidative stress and further exacerbate diabetes progression and its complications. Vascular dysfunction and damage to cellular proteins, membrane lipids and nucleic acids can stem from overproduction and/or insufficient removal of free radicals. The aim of this article is to review the literature regarding the use of antidiabetic drugs and their role in glycemic control in patients with heart failure and oxidative stress. Metformin exerts a minor benefit to these patients. Thiazolidinediones are not recommended in diabetic patients, as they increase the risk of HF. There is a lack of robust evidence on the use of meglinitides and acarbose. Insulin and dipeptidyl peptidase-4 (DPP-4) inhibitors may have a neutral cardiovascular effect on diabetic patients. The majority of current research focuses on sodium glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists. SGLT2 inhibitors induce positive cardiovascular effects in diabetic patients, leading to a reduction in cardiovascular mortality and HF hospitalization. GLP-1 receptor agonists may also be used in HF patients, but in the case of chronic kidney disease, SLGT2 inhibitors should be preferred.

Metformin mitigates stress-induced premature senescence by upregulating AMPKα at Ser485 phosphorylation induced SIRT3 expression and inactivating mitochondrial oxidants

The senescence of vascular smooth muscle cells (VSMCs) is an important cause of cardiovascular disease such as atherosclerosis and hypertension. These senescence may be triggered by many factors, such as oxidative stress, inflammation, DNA damage, and senescence-associated secretory phenotypes (SASPs). Mitochondrial oxidative stress induces cellular senescence, but the mechanisms by which mitochondrial reactive oxygen species (mtROS) regulates cellular senescence are still largely unknown. Here, we investigated the mechanism responsible for the anti-aging effect of metformin by examining links between VSMC senescence and mtROS in in vitro and in vivo. Metformin was found to increase p-AMPK (Ser485), but to decrease senescence-associated phenotypes and protein levels of senescence markers during ADR-induced VSMC senescence. Importantly, metformin decreased mtROS by inducing the deacetylation of superoxide dismutase 2 (SOD2) by increasing SIRT3 expression. Moreover, AMPK depletion reduced the expression of SIRT3 and increased the expression of acetylated SOD2 despite metformin treatment, suggesting AMPK activation by metformin is required to protect against mitochondrial oxidative stress by SIRT3. This study provides mechanistic evidence that metformin acts as an anti-aging agent and alleviates VSMC senescence by upregulating mitochondrial antioxidant induced p-AMPK (Ser485)-dependent SIRT3 expression, which suggests metformin has therapeutic potential for the treatment of age-associated vascular disease.

The role of MicroRNA networks in tissue-specific direct and indirect effects of metformin and its application

Metformin is a first-line oral antidiabetic agent that results in clear benefits in relation to glucose metabolism and diabetes-related complications. The specific regulatory details and mechanisms underlying these benefits are still unclear and require further investigation. There is recent mounting evidence that metformin has pleiotropic effects on the target tissue development in metabolic organs, including adipose tissue, the gastrointestinal tract and the liver. The mechanism of actions of metformin are divided into direct effects on target tissues and indirect effects via non-targeted tissues. MicroRNAs (miRNAs) are a class of endogenous, noncoding, negative gene regulators that have emerged as important regulators of a number of diseases, including type 2 diabetes mellitus (T2DM). Metformin is involved in many aspects of miRNA regulation, and metformin treatment in T2DM should be associated with other miRNA targets. A large number of miRNAs regulation by metformin in target tissues with either direct or indirect effects has gradually been revealed in the context of numerous diseases and has gradually received increasing attention. This paper thoroughly reviews the current knowledge about the role of miRNA networks in the tissue-specific direct and indirect effects of metformin. Furthermore, this knowledge provides a novel theoretical basis and suggests therapeutic targets for the clinical treatment of metformin and miRNA regulators in the prevention and treatment of cancer, cardiovascular disorders, diabetes and its complications.