Metformin Inhibits ROS Production by Human M2 Macrophages via the Activation of AMPK

Comparative effects of the antioxidant glutathione with metformin and Diane-35 on hormonal, metabolic, and inflammatory indicators in a DHEA-induced PCOS rat model

OBJECTIVE

Comparison of hormonal, metabolic and inflammatory markers of glutathione with metformin and Diane-35 in a rat model of PCOS induced by dehydroepiandrosterone.

METHODS

Twenty-five female rats were randomized into four groups. Group 1 was administered a subcutaneous dose of 0.2 ml saline/day. Group 2 was given 0.2 ml of 1% carboxymethyl cellulose (CMC)/day orally for 28 days. A PCOS model was established with DHEA in rats. Group 3 was given 4.5 mg/kg/day of Diane-35 orally dissolved in 1% CMC for 28 days. Group 4 was given 300 mg/kg/day of metformin orally dissolved in 1 ml of saline for 28 days, and Group 5 was administered 100 mg/kg of glutathione intraperitoneally on days 35, 42, and 49. On day 56, the rats were sacrificed. Serum markers and follicle count were examined.

RESULTS

Serum IL-6, hs-CRP, insulin, testosterone, SHBG, and MDA values were significantly lower in the glutathione group than in the PCOS group (p = 0.0006, p = 0.023, p = 0.0082, p = 0.0007, p = 0.0048, and p < 0.0001, respectively).The number of all follicles was similar between the control and glutathione groups (p < 0.05). When we compared the other groups with the PCOS group, the number of primary, secondary, atretic, and cystic follicles was significantly lower in the metformin and glutathione groups. The number of primordial and antral follicles was significantly higher than in the PCOS group.

CONCLUSIONS

Glutathione plays anti-inflammatory and antioxidant roles, similar to metformin, by lowering serum IL-6, insulin, testosterone, CRP, and MDA levels; decreasing atretic/cystic follicle count; and improving antral follicle count and folliculogenesis in PCOS patients.

Central administration of AICAR attenuates hypertension via AMPK/Nrf2 pathway in the hypothalamic paraventricular nucleus of hypertensive rats

BACKGROUND

Oxidative stress and inflammatory cytokines in the hypothalamus paraventricular nucleus (PVN) have been implicated in sympathetic nerve activity and the development of hypertension, but the specific mechanisms underlying their production in the PVN remains to be elucidated. Previous studies have demonstrated that activation of nuclear transcription related factor-2 (Nrf2) in the PVN reduced the production of reactive oxygen species (ROS) and inflammatory mediators. Moreover, AMP-activated protein kinase (AMPK), has been observed to decrease ROS and inflammatory cytokine production when activated in the periphery. 5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide (AICAR) is an AMPK agonist. However, little research has been conducted on the role of AMPK in the PVN during hypertension. Therefore, we hypothesized that AICAR in the PVN is involved in regulating AMPK/Nrf2 pathway, affecting ROS and inflammatory cytokine expression, influencing sympathetic nerve activity.

METHODS

Adult male Sprague-Dawley rats were utilized to induce two-kidney, one-clip (2K1C) hypertension via constriction of the right renal artery. Bilateral PVN was microinjected with either artificial cerebrospinal fluid or AICAR once a day for 4 weeks.

RESULTS

Compared to the SHAM group, the PVN of 2K1C hypertensive rats decreased p-AMPK and p-Nrf2 expression, increased Fra-Like, NAD(P)H oxidase (NOX)2, NOX4, tumor necrosis factor-α and interleukin (IL)-1β expression, elevated ROS levels, decreased superoxide dismutase 1 and IL-10 expression, and elevated plasma norepinephrine levels. Bilateral PVN microinjection of AICAR significantly ameliorated these changes.

CONCLUSION

These findings suggest that repeated injection of AICAR in the PVN suppresses ROS and inflammatory cytokine production through the AMPK/Nrf2 pathway, reducing sympathetic nerve activity and improving hypertension.

TBC1D1 is an energy-responsive polarization regulator of macrophages via governing ROS production in obesity

Energy status is linked to the production of reactive oxygen species (ROS) in macrophages, which is elevated in obesity. However, it is unclear how ROS production is upregulated in macrophages in response to energy overload for mediating the development of obesity. Here, we show that the Rab-GTPase activating protein (RabGAP) TBC1D1, a substrate of the energy sensor AMP-activated protein kinase (AMPK), is a critical regulator of macrophage ROS production and consequent adipose inflammation for obesity development. TBC1D1 deletion decreases, whereas an energy overload-mimetic non-phosphorylatable TBC1D1S231A mutation increases, ROS production and M1-like polarization in macrophages. Mechanistically, TBC1D1 and its downstream target Rab8a form an energy-responsive complex with NOX2 for ROS generation. Transplantation of TBC1D1S231A bone marrow aggravates diet-induced obesity whereas treatment with an ultra-stable TtSOD for removal of ROS selectively in macrophages alleviates both TBC1D1S231A mutation- and diet-induced obesity. Our findings therefore have implications for drug discovery to combat obesity.

Therapeutic strategies targeting mechanisms of macrophages in diabetic heart disease

Diabetic heart disease (DHD) is a serious complication in patients with diabetes. Despite numerous studies on the pathogenic mechanisms and therapeutic targets of DHD, effective means of prevention and treatment are still lacking. The pathogenic mechanisms of DHD include cardiac inflammation, insulin resistance, myocardial fibrosis, and oxidative stress. Macrophages, the primary cells of the human innate immune system, contribute significantly to these pathological processes, playing an important role in human disease and health. Therefore, drugs targeting macrophages hold great promise for the treatment of DHD. In this review, we examine how macrophages contribute to the development of DHD and which drugs could potentially be used to target macrophages in the treatment of DHD.

Akebia saponin D attenuates allergic airway inflammation through AMPK activation

Akebia saponin D (ASD) is a bioactive triterpenoid saponin extracted from Dipsacus asper Wall. ex DC.. This study aimed to investigate the effects of ASD on allergic airway inflammation. Human lung epithelial BEAS-2B cells and bone marrow-derived mast cells (BMMCs) were pretreated with ASD (50, 100 and 200 μΜ) and AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) (1 mM), and then stimulated with lipopolysaccharide (LPS) or IL-33. Pretreatment with ASD and AICAR significantly inhibited TNF-α and IL-6 production from BEAS-2B cells, and IL-13 production from BMMCs. Moreover, pretreatment with ASD and AICAR significantly increased p-AMPK expression in BEAS-2B cells. Inhibition of AMPK by siRNA and compound C partly abrogated the suppression effect of ASD on TNF-α, IL-6, and IL-13 production. Asthma murine model was induced by ovalbumin (OVA) challenge and treated with ASD (150 and 300 mg/kg) or AICAR (100 mg/kg). Infiltration of eosinophils, neutrophils, monocytes, and lymphocytes, and production of TNF-α, IL-6, IL-4, and IL-13 were attenuated in ASD and AICAR treated mice. Lung histopathological changes were also ameliorated after ASD and AICAR treatment. Additionally, it showed that treatment with ASD and AICAR increased p-AMPK expression in the lung tissues. In conclusion, ASD exhibited protective effects on allergic airway inflammation through the induction of AMPK activation.

Radical-Generating Activity, Phagocytosis, and Mechanical Properties of Four Phenotypes of Human Macrophages

Macrophages are the major players and orchestrators of inflammatory response. Expressed proteins and secreted cytokines have been well studied for two polar macrophage phenotypes-pro-inflammatory M1 and anti-inflammatory regenerative M2, but little is known about how the polarization modulates macrophage functions. In this study, we used biochemical and biophysical methods to compare the functional activity and mechanical properties of activated human macrophages differentiated from monocyte with GM-CSF (M0_GM) and M-CSF (M0_M) and polarized into M1 and M2 phenotypes, respectively. Unlike GM-CSF, which generates dormant cells with low activity, M-CSF confers functional activity on macrophages. M0_M and M2 macrophages had very similar functional characteristics-high reactive oxygen species (ROS) production level, and higher phagocytosis and survival compared to M1, while M1 macrophages showed the highest radical-generating activity but the lowest phagocytosis and survival among all phenotypes. All phenotypes decreased their height upon activation, but only M1 and M2 cells increased in stiffness, which can indicate a decrease in the migration ability of these cells and changes in their interactions with other cells. Our results demonstrated that while mechanical properties differ between M0 and polarized cells, all four phenotypes of monocyte-derived macrophages differ in their functional activities, namely in cytokine secretion, ROS production, and phagocytosis. Within the broad continuum of human macrophages obtained in experimental models and existing in vivo, there is a diversity of phenotypes with varying combinations of both markers and functional activities.

AMPK signaling inhibits the differentiation of myofibroblasts: impact on age-related tissue fibrosis and degeneration

Disruption of the extracellular matrix (ECM) and an accumulation of fibrotic lesions within tissues are two of the distinctive hallmarks of the aging process. Tissue fibroblasts are mesenchymal cells which display an impressive plasticity in the regulation of ECM integrity and thus on tissue homeostasis. Single-cell transcriptome studies have revealed that tissue fibroblasts exhibit a remarkable heterogeneity with aging and in age-related diseases. Excessive stress and inflammatory insults induce the differentiation of fibroblasts into myofibroblasts which are fusiform contractile cells and abundantly secrete the components of the ECM and proteolytic enzymes as well as many inflammatory mediators. Detrimental stresses can also induce the transdifferentiation of certain mesenchymal and myeloid cells into myofibroblasts. Interestingly, many age-related stresses, such as oxidative and endoplasmic reticulum stresses, ECM stiffness, inflammatory mediators, telomere shortening, and several alarmins from damaged cells are potent inducers of myofibroblast differentiation. Intriguingly, there is convincing evidence that the signaling pathways stimulated by the AMP-activated protein kinase (AMPK) are potent inhibitors of myofibroblast differentiation and accordingly AMPK signaling reduces fibrotic lesions within tissues, e.g., in age-related cardiac and pulmonary fibrosis. AMPK signaling is not only an important regulator of energy metabolism but it is also able to control cell fate determination and many functions of the immune system. It is known that AMPK signaling can delay the aging process via an integrated signaling network. AMPK signaling inhibits myofibroblast differentiation, e.g., by suppressing signaling through the TGF-β, NF-κB, STAT3, and YAP/TAZ pathways. It seems that AMPK signaling can alleviate age-related tissue fibrosis and degeneration by inhibiting the differentiation of myofibroblasts.

O6-methylguanine DNA methyltransferase regulates β-glucan-induced trained immunity of macrophages via farnesoid X receptor and AMPK

Trained immunity is the heightened state of innate immune memory that enhances immune response resulting in nonspecific protection. Epigenetic changes and metabolic reprogramming are critical steps that regulate trained immunity. In this study, we reported the involvement of O6-methylguanine DNA methyltransferase (MGMT), a DNA repair enzyme of lesion induced by alkylating agents, in regulation the trained immunity induced by β-glucan (BG). Pharmacological inhibition or silencing of MGMT expression altered LPS stimulated pro-inflammatory cytokine productions in BG-trained bone marrow derived macrophages (BMMs). Targeted deletion of Mgmt in BMMs resulted in reduction of the trained responses both in vitro and in vivo models. The transcriptomic analysis revealed that the dampening trained immunity in MGMT KO BMMs is partially mediated by ATM/FXR/AMPK axis affecting the MAPK/mTOR/HIF1α pathways and the reduction in glycolysis function. Taken together, a failure to resolve a DNA damage may have consequences for innate immune memory.

The Role and Mechanism of Metformin in Inflammatory Diseases

Metformin is a classical drug used to treat type 2 diabetes. With the development of research on metformin, it has been found that metformin also has several advantages aside from its hypoglycemic effect, such as anti-inflammatory, anti-aging, anti-cancer, improving intestinal flora, and other effects. The prevention of inflammation is critical because chronic inflammation is associated with numerous diseases of considerable public health. Therefore, there has been growing interest in the role of metformin in treating various inflammatory conditions. However, the precise anti-inflammatory mechanisms of metformin were inconsistent in the reported studies. Thus, this review aims to summarize various currently known possible mechanisms of metformin involved in inflammatory diseases and provide references for the clinical application of metformin.

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.

Immune function of colon cancer associated miRNA and target genes

Introduction

Colon cancer is a complex disease that involves intricate interactions between cancer cells and theimmune microenvironment. MicroRNAs (miRNAs) have recently emerged as critical regulators of gene expression in cancer, including colon cancer. There is increasing evidence suggesting that miRNA dysregulation plays a crucial role in modulating the immune microenvironment of intestinal cancer. In particular, miRNAs regulate immune cell activation, differentiation, and function, as well as cytokine and chemokine production in intestinal cancer. It is urgent to fully investigate the potential role of intestinal cancer-related miRNAs in shaping the immune microenvironment.

Methods

Therefore, this paper aims to identify miRNAs that are potentially associated with colon cancer and regulate a large number of genes related to immune function. We explored the role of these genes in colon cancer patient prognosis, immune infiltration, and tumor purity based on data of 174 colon cancer patients though convolutional neural network, survival analysis and multiple analysis tools.

Results

Our findings suggest that miRNA regulated genes play important roles in CD4 memory resting cells, macrophages.M2, and Mast cell activated cells, and they are concentrated in the cytokinecytokine receptor interaction pathway.

Discussion

Our study enhances our understanding of the underlying mechanisms of intestinal cancer and provides new insights into the development of effective therapies. Additionally, identification of miRNA biomarkers could aid in diagnosis and prognosis, as well as guide personalized treatment strategies for patients with intestinal cancer.

Macrophage Mitochondrial Biogenesis and Metabolic Reprogramming Induced by Leishmania donovani Require Lipophosphoglycan and Type I Interferon Signaling

Pathogen-specific rewiring of host cell metabolism creates the metabolically adapted microenvironment required for pathogen replication. Here, we investigated the mechanisms governing the modulation of macrophage mitochondrial properties by the vacuolar pathogen Leishmania. We report that induction of oxidative phosphorylation and mitochondrial biogenesis by Leishmania donovani requires the virulence glycolipid lipophosphoglycan, which stimulates the expression of key transcriptional regulators and structural genes associated with the electron transport chain. Leishmania-induced mitochondriogenesis also requires a lipophosphoglycan-independent pathway involving type I interferon (IFN) receptor signaling. The observation that pharmacological induction of mitochondrial biogenesis enables an avirulent lipophosphoglycan-defective L. donovani mutant to survive in macrophages supports the notion that mitochondrial biogenesis contributes to the creation of a metabolically adapted environment propitious to the colonization of host cells by the parasite. This study provides novel insight into the complex mechanism by which Leishmania metacyclic promastigotes alter host cell mitochondrial biogenesis and metabolism during the colonization process. IMPORTANCE To colonize host phagocytes, Leishmania metacyclic promastigotes subvert host defense mechanisms and create a specialized intracellular niche adapted to their replication. This is accomplished through the action of virulence factors, including the surface coat glycoconjugate lipophosphoglycan. In addition, Leishmania induces proliferation of host cell mitochondria as well as metabolic reprogramming of macrophages. These metabolic alterations are crucial to the colonization process of macrophages, as they may provide metabolites required for parasite growth. In this study, we describe a new key role for lipophosphoglycan in the stimulation of oxidative phosphorylation and mitochondrial biogenesis. We also demonstrate that host cell pattern recognition receptors Toll-like receptor 4 (TLR4) and endosomal TLRs mediate these Leishmania-induced alterations of host cell mitochondrial biology, which also require type I IFN signaling. These findings provide new insight into how Leishmania creates a metabolically adapted environment favorable to their replication.

Wound Healing versus Metastasis: Role of Oxidative Stress

Many signaling pathways, molecular and cellular actors which are critical for wound healing have been implicated in cancer metastasis. These two conditions are a complex succession of cellular biological events and accurate regulation of these events is essential. Apart from inflammation, macrophages-released ROS arise as major regulators of these processes. But, whatever the pathology concerned, oxidative stress is a complicated phenomenon to control and requires a finely tuned balance over the different stages and responding cells. This review provides an overview of the pivotal role of oxidative stress in both wound healing and metastasis, encompassing the contribution of macrophages. Indeed, macrophages are major ROS producers but also appear as their targets since ROS interfere with their differentiation and function. Elucidating ROS functions in wound healing and metastatic spread may allow the development of innovative therapeutic strategies involving redox modulators.