Monocytes: a novel drug delivery system targeting atherosclerosis

In situ customized apolipoprotein B48-enriched protein corona enhances oral gene delivery of chitosan-based nanoparticles

The formation of protein corona (PC) is important for promoting the in vivo delivery of nanoparticles (NPs). However, PC formed in the physiological environment of oral delivery is poorly understood. Here, we engineered seven types of trimethyl chitosan-cysteine (TC) NPs, with distinct molecular weights, quaternization degrees, and thiolation degrees, to deeply investigate the influence of various PC formed in the physiological environment of oral delivery on in vivo gene delivery of polymeric NPs, further constructing the relationship between the surface characteristics of NPs and the efficacy of oral gene delivery. Our findings reveal that TC7 NPs, with high molecular weight, moderate quaternization, and high sulfhydryl content, modulate PC formation in the gastrointestinal tract, thereby reducing particle size and promoting oral delivery of gene loaded TC7 NPs. Orally delivered TC7 NPs target macrophages by in situ adsorption of apolipoprotein (Apo) B48 in intestinal tissue, leading to the improved in vivo antihepatoma efficacy via the natural tumor homing ability of macrophages. Our results suggest that efficient oral delivery of genes can be achieved through an in situ customized ApoB48-enriched PC, offering a promising modality in treating macrophage-related diseases.

Advanced Applications of Nanomaterials in Atherosclerosis Diagnosis and Treatment: Challenges and Future Prospects

Atherosclerosis-induced coronary artery disease is a major cause of cardiovascular mortality. Clinically, conservative treatment strategies for atherosclerosis still focus on lifestyle interventions and the use of lipid-lowering and anticoagulant medications. Despite achieving some therapeutic effects, these approaches are limited by low bioavailability, long intervention periods, and significant side effects. With the advancement of nanotechnology, nanomaterials have demonstrated extraordinary potential in the biomedical field. Their excellent biocompatibility, surface modifiability, and high targeting capability not only enable efficient diagnosis of plaque progression but also allow precise drug delivery within atherosclerotic plaques, significantly enhancing drug bioavailability and reducing systemic side effects. Here, we systematically review the current research progress of nanomaterials in the field of atherosclerosis to summarize not only the types of nanomaterials but also their applications in both the diagnosis and treatment of atherosclerosis. Notably, in the context of plaque therapy, we provide a comprehensive overview of current nanomaterial applications based on their targeted therapeutic systems for different cell types within plaques. Additionally, we address the persistent challenge of clinical translation of nanomaterials by summarizing current issues and providing directions for innovation and improvement in nanomaterial design. Overall, we believe that this review systematically summarizes the applications and challenges of biomedical nanomaterials in atherosclerosis diagnosis and therapy, thereby offering insights and references for the development of therapeutic materials for atherosclerosis.

Biomimetic Nanoparticles for the Diagnosis and Therapy of Atherosclerosis

Atherosclerosis (AS) is a chronic inflammation of blood vessels, which often has no obvious symptoms in the early stage of the disease, but when atherosclerotic plaques are formed, they often cause lumen blockage, and even plaque rupture leads to thrombosis, that is the essential factor of cardiovascular events, for example myocardial infarction, cerebral infarction, and renal atrophy. Therefore, it is considerably significant for the early recognition and precise therapy of plaque. Biomimetic nanoparticles (BNPs), especially those coated with cell membranes, can retain the biological function of cell membranes or cells, which has led to extensive research and application in the diagnosis and treatment of AS in recent years. In this review, we summarized the roles of various key cells in AS progression, the construction of biomimetic nanoparticles based on these key cells as well as their applications in AS diagnosis and therapy. Furthermore, we give a challenge and prospect of biomimetic nanoparticles in AS, hoping to elevate their application quality and the possibility of clinical translation.

Potential applications of macrophages in cancer immunotherapy

Immunotherapy has improved cancer treatment based on investigations of tumor immune escape. Manipulation of the immune system stimulates antitumor immune responses and blocks tumor immune escape routes. Genetically adoptive cell therapy, such as T cells, has yielded promising results for hematologic malignancies, but their application to solid tumors has been challenging. Macrophages have a wide broad of capabilities in regulating immune responses, homeostasis, and tissue development, as well as the ability to phagocyte, present antigens, and infiltrate the tumor microenvironment (TME). Given the importance of macrophages in cancer development, they could serve as novel tool for tumor treatment. Therefore, macrophages are used in different formats for direct and indirect targeting of tumor cells. This review summarized the available data on the various applications of macrophages in cancer immunotherapy.

Biomimetic Systems Involving Macrophages and Their Potential for Targeted Drug Delivery

The concept of targeted drug delivery can be described in terms of the drug systems' ability to mimic the biological objects' property to localize to target cells or tissues. For example, drug delivery systems based on red blood cells or mimicking some of their useful features, such as long circulation in stealth mode, have been known for decades. On the contrary, therapeutic strategies based on macrophages have gained very limited attention until recently. Here, we review two biomimetic strategies associated with macrophages that can be used to develop new therapeutic modalities: first, the mimicry of certain types of macrophages (i.e., the use of macrophages, including tumor-associated or macrophage-derived particles as a carrier for the targeted delivery of therapeutic agents); second, the mimicry of ligands, naturally absorbed by macrophages (i.e., the use of therapeutic agents specifically targeted at macrophages). We discuss the potential applications of biomimetic systems involving macrophages for new advancements in the treatment of infections, inflammatory diseases, and cancer.

Biomimetic nanomedicines for precise atherosclerosis theranostics

Atherosclerosis (AS) is a leading cause of the life-threatening cardiovascular disease (CVD), creating an urgent need for efficient, biocompatible therapeutics for diagnosis and treatment. Biomimetic nanomedicines (bNMs) are moving closer to fulfilling this need, pushing back the frontier of nano-based drug delivery systems design. This review seeks to outline how these nanomedicines (NMs) might work to diagnose and treat atherosclerosis, to trace the trajectory of their development to date and in the coming years, and to provide a foundation for further discussion about atherosclerotic theranostics.

Anti-inflammation-based treatment of atherosclerosis using Gliclazide-loaded biomimetic nanoghosts

In the study, a biomimetic platform for anti-inflammatory-based treatment of atherosclerotic plaque was developed. Gliclazide (GL) as an anti-inflammasome agent was encapsulated in PLGA nanoparticles (NP), which were coated by monocyte membrane using an extrusion procedure. The size and zeta potential of the nanoghost (NG) changed to 292 and - 10 nm from 189.5 to -34.1 in the core NP. In addition, the actual size of 62.5 nm with a coating layer of 5 nm was measured using TEM. The NG was also showed a sustained release profile with the drug loading content of about 4.7%. Beside to attenuated TNFα, decrease in gene expression levels of NLRP3, MyD88, NOS, IL-1β, IL-18 and caspases 1/3/8/9 in LPS-primed monocytes exposed to NG strongly indicated remarkable inflammation control. After systemic toxicity evaluation and pharmacokinetic analysis of NP and NG, intravenous NG treatment of rabbits with experimentally induced atherosclerosis revealed remarkably less plaque lesions, foam cells, lipid-laden macrophages, and pathological issues in tunica media of aorta sections. Higher expression of CD163 than CD68 in aorta of NG-treated rabbits strongly reveals higher M2/M1 macrophage polarization. The bio/hemocompatible, biomimetic and anti-inflammatory NG can be considered as a potential platform for immunotherapy of particularly atherosclerosis in the field of personalized medicine.

Macrophage cell membrane-based nanoparticles: a new promising biomimetic platform for targeted delivery and treatment

Synthetic nanoparticles with surface bioconjugation are promising platforms for targeted therapy, but their simple biological functionalization is still a challenging task against the complex intercellular environment. Once synthetic nanoparticles enter the body, they are phagocytosed by immune cells by the immune system. Recently, the cell membrane camouflage strategy has emerged as a novel therapeutic tactic to overcome these issues by utilizing the fundamental properties of natural cells. Macrophage, a type of immune system cells, plays critical roles in various diseases, including cancer, atherosclerosis, rheumatoid arthritis, infection and inflammation, due to the recognition and engulfment function of removing substances and pathogens. Macrophage membranes inherit the surface protein profiles and biointerfacing properties of source cells. Therefore, the macrophage membrane cloaking can protect synthetic nanoparticles from phagocytosis by the immune cells. Meanwhile, the macrophage membrane can make use of the natural correspondence to accurately recognize antigens and target inflamed tissue or tumor sites. In this review, we have summarized the advances in the fabrication, characterization and homing capacity of macrophage membrane cloaking nanoparticles in various diseases, including cancers, immune diseases, cardiovascular diseases, central nervous system diseases, and microbial infections. Although macrophage membrane-camouflaged nanoparticles are currently in the fetal stage of development, there is huge potential and challenge to explore the conversion mode in the clinic.

Nanotechnological approach to delivering nutraceuticals as promising drug candidates for the treatment of atherosclerosis

Atherosclerosis is Caesar's sword, which poses a huge risk to the present generation. Understanding the atherosclerotic disease cycle would allow ensuring improved diagnosis, better care, and treatment. Unfortunately, a highly effective and safe way of treating atherosclerosis in the medical community remains a continuous challenge. Conventional treatments have shown considerable success, but have some adverse effects on the human body. Natural derived medications or nutraceuticals have gained immense popularity in the treatment of atherosclerosis due to their decreased side effects and toxicity-related issues. In hindsight, the contribution of nutraceuticals in imparting enhanced clinical efficacy against atherosclerosis warrants more experimental evidence. On the other hand, nanotechnology and drug delivery systems (DDS) have revolutionized the way therapeutics are performed and researchers have been constantly exploring the positive effects that DDS brings to the field of therapeutic techniques. It could be as exciting as ever to apply nano-mediated delivery of nutraceuticals as an additional strategy to target the atherosclerotic sites boasting high therapeutic efficiency of the nutraceuticals and fewer side effects.

Nano-engineered immune cells as "guided missiles" for cancer therapy

Immune cells can actively regulate tumors or inflammatory sites and have good biocompatibility and safety. Currently, they are one of the most promising candidates for drug delivery systems. Moreover, immune cells can significantly extend the circulation time of nanoparticles and have broad-spectrum tumor-targeting properties. This article first introduces the immune cell types most commonly used in recent years, analyzes their advantages and disadvantages, and elucidates their application in anti-tumor therapy. Next, the various ways of loading nanoparticles on immune cells that have been used in recent years are summarized and simply divided into two categories: backpacks and Trojan horses. Finally, the two "mountains" that stand in front of us when using immune cells as cell carriers, off-target problems and effective release strategies, are discussed.

Low efficiency of leucocyte plugging-based drug delivery to cancer in mice

Cells of the immune system were proposed for use as Trojan horse for tumour-specific drug delivery. The efficacy of such cell-based drug delivery depends on the site-specific cell homing. This present study was aimed to investigate the potential of leucocytes for intratumoural site-specific enrichment using a locoregional application route in experimental liver tumours. Human neutrophils were isolated from peripheral blood and directly labelled with calcein AM or loaded with doxorubicin. The neutrophil loading and release of doxorubicin and the migration and adhesion to ICAM-1 were analysed in vitro. Macrophages were isolated and activated in vitro. Leucocyte plugging and the distribution pattern in the liver microvasculature were studied ex vivo, and the efficacy of leucocyte plugging in tumour blood vessels was analysed in vivo after superselective intra-arterial injection in mouse liver tumour models. Neutrophils were characterised by the high dose-dependent uptake and rapid release of doxorubicin. Doxorubicin loading did not affect neutrophil migration function. Neutrophil plugging in liver microvasculature was very high (> 90%), both after ex vivo perfusion and after injection in vivo. However, neutrophils as well as activated macrophages plugged insufficiently in tumour blood vessels and passed through the tumour microvasculture with a very low sequestration rate in vivo. Neutrophils possess several properties to function as potentially effective drug carriers; however, the tumour site-specific drug delivery after selective locoregional injection was observed to be insufficient owing to low intratumoural microvascular plugging.

Cell-mediated targeting drugs delivery systems

Drug delivery systems have shown tremendous promise to improve the diagnostic and therapeutic effects of drugs due to their special property. Targeting tissue damage, tumors, or drugs with limited toxicity at the site of infection is the goal of successful pharmaceuticals. Targeted drug delivery has become significantly important in enhancing the pharmaceutical effects of drugs and reducing their side effects of therapeutics in the treatment of various disease conditions. Unfortunately, clinical translation of these targeted drug delivery system mechanisms faces many challenges. At present, only a few targeted drug delivery systems can achieve high targeting efficiency after intravenous injection, even though numerous surface markers and targeting approaches have been developed. Thus, cell-mediated drug-delivery targeting systems have received considerable attention for their enhanced therapeutic specificity and efficacy in the treatment of the disease. This review highlights the recent advances in the design of the different types of cells that have been explored for cell-mediated drug delivery and targeting mechanisms. A better understanding of cell biology orientation and a new generation of delivery strategies that utilize these endogenous approaches are expected to provide better solutions for specific site delivery and further facilitate clinical translation.

Recent Advances in Macrophage-Mediated Drug Delivery Systems

Macrophages have been extensively used in the development of drug delivery systems, as they can prolong the circulation and release of drugs, extend their half-life, increase their stability and targeting ability, and reduce immunogenicity. Moreover, they have good biocompatibility and degradability and offer abundant surface receptors for targeted delivery of a wide variety of drugs. Macrophage-mediated drug delivery systems can be prepared by loading drugs or drug-loaded nanoparticles into macrophages, macrophage membranes or macrophage-derived vesicles. Although such systems can be used to treat inflammation, cancer, HIV infection and other diseases, they require further research and optimization since they have been assembled from diverse sources and therefore can have quite different physical and chemical properties. Moreover, potential cell-drug interactions can limit their application, and the biological activity of membrane proteins might be lost during membrane extraction and storage. In this review, we summarize the recent advances in this field and discuss the preparation of macrophage-mediated drug delivery systems, their advantages over other delivery systems, their potential applications and future lines of research.

Biofluidic material-based carriers: Potential systems for crossing cellular barriers

Biofluids act as a repository for disease biomarkers and are excellent diagnostic tools applied in establishing a disease profile based on clinical testing, evaluation and monitoring the progression of patients suffering from various conditions. Furthermore, biofluids and their derived components such proteins, pigments, enzymes, hormones and cells carry a potential in the development of therapeutic drug delivery systems or as cargo materials for targeting the drug to the site of action. The presence of biofluids with respect to their specific location reveals the information of disease progression and mechanism, delivery aspects such as routes of administration as well as pharmacological factors such as binding affinity, rate of kinetics, efficacy, bioavailability and patient compliance. This review focuses on the properties and functional benefits of some biofluids, namely blood, saliva, bile, urine, amniotic fluid, synovial fluid and cerebrospinal fluid. It also covers the therapeutic and targeting action of fluid-derived substances in various micro- or nano-systems like nanohybrids, nanoparticles, self-assembled micelles, microparticles, cell-based systems, etc. The formulation of such biologically-oriented systems demonstrate the advantages of natural origin, biocompatibility and biodegradability and offer new techniques for overcoming the challenges experienced in conventional therapies.

Cell-derived biomimetic nanoparticles as a novel drug delivery system for atherosclerosis: predecessors and perspectives

Atherosclerosis is a key mechanism underlying the pathogenesis of cardiovascular disease, which is associated with high morbidity and mortality. In the field of precision medicine for the treatment of atherosclerosis, nanoparticle (NP)-mediated drug delivery systems have great potential, owing to their ability to release treatment locally. Cell-derived biomimetic NPs have attracted extensive attention at present due to their excellent targeting to atherosclerotic inflammatory sites, low immunogenicity and long blood circulation time. Here, we review the utility of cell-derived biomimetic NPs, including whole cells, cell membranes and extracellular vesicles, in the treatment of atherosclerosis.

A bioinspired hyperthermic macrophage-based polypyrrole-polyethylenimine (Ppy-PEI) nanocomplex carrier to prevent and disrupt thrombotic fibrin clots

Fibrinolytic treatments for venous or arterial thrombotic syndromes using systemic administration of thrombolytics, such as streptokinase, can induce life-threatening bleeding complications. In this study, we offer the first proof of concept for a targeted photothermal fibrin clot prevention and reduction technology using macrophages loaded with polypyrrole-polyethylenimine nanocomplexes (Ppy-PEI NCs) and subjected to near-infrared radiation (NIR). We first show that the developed Ppy-PEI NCs could be taken up by defensive macrophages in vitro through endocytosis. The Ppy-PEI NCs generated local hyperthermia upon NIR treatment, which appeared to produce reactive oxygen species in Ppy-PEI NC-loaded macrophages. Preliminary evidence of efficacy as an antithrombotic tool is provided, in vitro, using fibrinogen-converted fibrin clots, and in vivo, in a rat femoral vascular thrombosis model generated by exposure to ferric chloride substance. The in vivo biocompatibility, photothermal behavior, biodistribution, and histological observation of cellular interactions with the Ppy-PEI NCs in the rat model provide rationale in support of further preclinical studies. This Ppy-PEI NC/NIR-based method, which uses a unique macrophage-guided targeting approach to prevent and lyse fibrin clots, may potentially overcome some of the disadvantages of current thrombolytic treatments. STATEMENT OF SIGNIFICANCE: Fibrinolytic treatments for venous or arterial thrombotic syndromes using systemic administration of thrombolytics, such as streptokinase, can induce life-threatening bleeding complications. In this study, we offer the first proof of concept for a targeted photothermal fibrin clot reduction technology using macrophages loaded with polypyrrole-polyethylenimine nanocomplexes (Ppy-PEI NCs) and subjected to near-infrared radiation (NIR). We first show that the developed Ppy-PEI NCs can be taken up by defensive macrophages in vitro through endocytosis. The Ppy-PEI NCs generated local hyperthermia upon NIR treatment, which appeared to produce reactive oxygen species in Ppy-PEI NC-loaded macrophages. Preliminary evidence of efficacy as an antithrombotic tool is provided, in vitro, using fibrinogen-converted fibrin clots, and in vivo, in a rat femoral vascular thrombosis model generated by exposure to ferric chloride substance. The in vivo biocompatibility, photothermal behavior, biodistribution, and histological observation of cellular interactions with the Ppy-PEI NCs in the rat model provide rationale in support of further preclinical studies. This Ppy-PEI NC/NIR-based method, which uses a unique macrophage-guided targeting approach to disintegrate fibrin clots, may potentially overcome some of the disadvantages of current thrombolytic treatments.

Exploiting macrophages as targeted carrier to guide nanoparticles into glioma

The restriction of anti-cancer drugs entry to tumor sites in the brain is a major impediment to the development of new strategies for the treatment of glioma. Based on the finding that macrophages possess an intrinsic homing property enabling them to migrate to tumor sites across the endothelial barriers in response to the excretion of cytokines/chemokines in the diseased tissues, we exploited macrophages as 'Trojan horses' to carry drug-loading nanoparticles (NPs), pass through barriers, and offload them into brain tumor sites. Anticancer drugs were encapsulated in nanoparticles to avoid their damage to the cells. Drug loading NPs was then incubated with RAW264.7 cells in vitro to prepare macrophage-NPs (M-NPs). The release of NPs from M-NPs was very slow in medium of DMEM and 10% FBS and significantly accelerated when LPS and IFN-γ were added to mimic tumor inflammation microenvironment. The viability of macrophages was not affected when the concentration of doxorubicin lower than 25 μg/ml. The improvement of cellular uptake and penetration into the core of glioma spheroids of M-NPs compared with NPs was verified in in vitro studies. The tumor-targeting efficiency of NPs was also significantly enhanced after loading into macrophages in nude mice bearing intracranial U87 glioma. Our results provided great potential of macrophages as an active biocarrier to deliver anticancer drugs to the tumor sites in the brain and improve therapeutic effects of glioma.

Monocyte-mediated chemotherapy drug delivery in glioblastoma

AIM

To mechanistically prove the concept of monocyte-mediated nano drug delivery in glioblastoma (GBM).

RESULTS

nano-doxorubicin-loaded monocytes (Nano-DOX-MC) were viable, able to cross an artificial endothelial barrier and capable of infiltrating GBM spheroids and releasing drug therein. GBM cells stimulated unloading of Nano-DOX-MC and took up the unloaded drug and released damage-associated molecular patterns. In mice with orthotopic GBM xenografts, Nano-DOX-MC resulted in much improved tumor drug delivery efficacy and damage-associated molecular patterns emission. Mechanistically, Nano-DOX was found sequestered in the lysosomal compartment and to induce autophagy, which may underlie MC's tolerance to Nano-DOX. Lysosomal exocytosis was found involved in the discharging mechanism of intracellular Nano-DOX.

CONCLUSION

Nano-DOX can be effectively delivered by MC in GBM and induce cancer cell damage.

A novel strategy to achieve effective drug delivery: exploit cells as carrier combined with nanoparticles

Cell-mediated drug delivery systems employ specific cells as drug vehicles to deliver drugs to targeted sites. Therapeutics or imaging agents are loaded into these cells and then released in diseased sites. These specific cells mainly include red blood cells, leukocytes, stem cells and so on. The cell acts as a Trojan horse to transfer the drug from circulating blood to the diseased tissue. In such a system, these cells keep their original properties, which allow them to mimic the migration behavior of specific cells to carry drug to the targeted site after in vivo administration. This strategy elegantly combines the advantages of both carriers, i.e. the adjustability of nanoparticles (NPs) and the natural functions of active cells, which therefore provides a new perspective to challenge current obstacles in drug delivery. This review will describe a fundamental understanding of these cell-based drug delivery systems, and discuss the great potential of combinational application of cell carrier and NPs.

Leukocyte-mediated Delivery of Nanotherapeutics in Inflammatory and Tumor Sites

Nanotechnology has become a powerful tool to potentially translate nanomedicine from bench to bedside. Nanotherapeutics are nanoparticles (NPs) loaded with drugs and possess the property of tissue targeting after surfaces of NPs are bio-functionalized. Designing smaller size of nanotherapeutics is presumed to increase tumor targeting based on the EPR (enhanced permeability and retention) effect. Since the immune systems possess a defence mechanism to fight diseases, there is an emerging concept that NPs selectively target immune cells to mediate the active delivery of drugs into sites of disease. In this review, we will focus on a key question of how nanotherapeutics specifically target immune cells and hijack them as a delivery vehicle to transport nanotherapeutics into disease tissues, thus possibly improving current therapies in inflammation, immune disorders and cancers. We will also discuss the challenges and opportunities for this new strategy of leukocyte-mediated delivery of nanotherapeutics.

Advances of blood cell-based drug delivery systems

Blood cells, including erythrocytes, leukocytes and platelets are used as drug carriers in a wide range of applications. They have many unique advantages such as long life-span in circulation (especially erythrocytes), target release capacities (especially platelets), and natural adhesive properties (leukocytes and platelets). These properties make blood cell based delivery systems, as well as their membrane-derived carriers, far superior to other drug delivery systems. Despite the advantages, the further development of blood cell-based delivery systems was hindered by limitations in the source, storage, and mass production. To overcome these problems, synthetic biomaterials that mimic blood cell and nanocrystallization of blood cells have been developed and may represent the future direction for blood cell membrane-based delivery systems. In this paper, we review recent progress of the rising blood cell-based drug delivery systems, and also discuss their challenges and future tendency of development.

Metformin reduces the expression of NADPH oxidase and increases the expression of antioxidative enzymes in human monocytes/macrophages cultured in vitro

The treatment of diabetes and its complications is a key challenge for healthcare professionals. Accelerated atherosclerosis is associated with progressive diabetes, and it has been indicated that macrophages serve a crucial function in this process. Currently, the first-line treatment of diabetes is based on metformin, which is an inducer of AMP-activated protein kinase (AMPK) and belongs to the biguanide class of pharmaceuticals. It has been previously demonstrated that metformin exhibits more than just hypoglycemic effects. Therefore, the aim of the present study was to investigate the in vitro impact of metformin on cell viability and the expression levels of nicotinamide adenine dinucleotide phosphate (NAPDH) oxidase (p22phox), a major enzyme in reactive oxygen species generation, and the three antioxidative enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) in monocytes/macrophages derived from 10 healthy volunteers. The effects of metformin were observed in the presence or absence of lipopolysaccharide (LPS), which was administered to induce oxidative stress. Furthermore, certain cells were treated with compound C, an inhibitor of AMPK, in order to determine the mechanistic role played by AMPK in the oxidative changes in the macrophages. Cell viability was evaluated using trypan blue and MTT assays. The mRNA and protein expression levels of p22phox and the various antioxidative enzymes were determined using polymerase chain reaction and western blot analysis, respectively. The results indicated that metformin, predominantly in LPS-pretreated monocytes/macrophages, reduced the expression levels of p22phox and increased those of SOD and GPx, but had only a minor effect on CAT levels. Therefore, metformin appears to alter the oxidative status of macrophages toward increasingly antioxidative activity, which may account for the pleiotropic effects observed during metformin treatment.