Metformin Activates the Protective Effects of the AMPK Pathway in Acute Lung Injury Caused by Paraquat Poisoning

Heyingwuzi formulation alleviates diabetic retinopathy by promoting mitophagy via the HIF-1α/BNIP3/NIX axis

BACKGROUND

Diabetic retinopathy (DR) is the primary cause of visual problems in patients with diabetes. The Heyingwuzi formulation (HYWZF) is effective against DR.

AIM

To determine the HYWZF prevention mechanisms, especially those underlying mitophagy.

METHODS

Human retinal capillary endothelial cells (HRCECs) were treated with high glucose (hg), HYWZF serum, PX-478, or Mdivi-1 in vitro. Then, cell counting kit-8, transwell, and tube formation assays were used to evaluate HRCEC proliferation, invasion, and tube formation, respectively. Transmission electron microscopy was used to assess mitochondrial morphology, and Western blotting was used to determine the protein levels. Flow cytometry was used to assess cell apoptosis, reactive oxygen species (ROS) production, and mitochondrial membrane potential. Moreover, C57BL/6 mice were established in vivo using streptozotocin and treated with HYWZF for four weeks. Blood glucose levels and body weight were monitored continuously. Changes in retinal characteristics were evaluated using hematoxylin and eosin, tar violet, and periodic acid-Schiff staining. Protein levels in retinal tissues were determined via Western blotting, immunohistochemistry, and immunostaining.

RESULTS

HYWZF inhibited excessive ROS production, apoptosis, tube formation, and invasion in hg-induced HRCECs via mitochondrial autophagy in vitro. It increased the mRNA expression levels of BCL2-interacting protein 3 (BNIP3), FUN14 domain-containing 1, BNIP3-like (BNIP3L, also known as NIX), PARKIN, PTEN-induced kinase 1, and hypoxia-inducible factor (HIF)-1α. Moreover, it downregulated the protein levels of vascular endothelial cell growth factor and increased the light chain 3-II/I ratio. However, PX-478 and Mdivi-1 reversed these effects. Additionally, PX-478 and Mdivi-1 rescued the effects of HYWZF by decreasing oxidative stress and apoptosis and increasing mitophagy. HYWZF intervention improved the symptoms of diabetes, tissue damage, number of acellular capillaries, and oxidative stress in vivo. Furthermore, in vivo experiments confirmed the results of in vitro experiments.

CONCLUSION

HYWZF alleviated DR and associated damage by promoting mitophagy via the HIF-1α/BNIP3/NIX axis.

Anti-Inflammatory Potential of the Anti-Diabetic Drug Metformin in the Prevention of Inflammatory Complications and Infectious Diseases Including COVID-19: A Narrative Review

Metformin, a widely used first-line anti-diabetic therapy for the treatment of type-2 diabetes, has been shown to lower hyperglycemia levels in the blood by enhancing insulin actions. For several decades this drug has been used globally to successfully control hyperglycemia. Lactic acidosis has been shown to be a major adverse effect of metformin in some type-2 diabetic patients, but several studies suggest that it is a typically well-tolerated and safe drug in most patients. Further, recent studies also indicate its potential to reduce the symptoms associated with various inflammatory complications and infectious diseases including coronavirus disease 2019 (COVID-19). These studies suggest that besides diabetes, metformin could be used as an adjuvant drug to control inflammatory and infectious diseases. In this article, we discuss the current understanding of the role of the anti-diabetic drug metformin in the prevention of various inflammatory complications and infectious diseases in both diabetics and non-diabetics.

Preclinical evidence using synthetic compounds and natural products indicates that AMPK represents a potential pharmacological target for the therapy of pulmonary diseases

Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) is a highly conserved eukaryotic enzyme discovered as a key regulator of cellular energy homeostasis, with anti-inflammation, antioxidative stress, anticancer, and antifibrosis beneficial effects. AMPK is dysregulated in human pulmonary diseases such as acute lung injury, nonsmall cell lung cancer, pulmonary fibrosis, chronic obstructive pulmonary disease, and asthma. This review provides an overview of the beneficial role of natural, synthetic, and Chinese traditional medicines AMPK modulators in pulmonary diseases, and highlights the role of the AMPK signaling pathway in the lung, emphasizing the importance of finding lead compounds and drugs that can target and modulate AMPK to treat the lung diseases.

Metformin alleviates benzo[a]pyrene-induced alveolar injury by inhibiting necroptosis and protecting AT2 cells

Exposure to benzo[a]pyrene (B[a]P) has been linked to lung injury and carcinogenesis. Airway epithelial cells express the B[a]P receptor AHR, so B[a]P is considered to mainly target airway epithelial cells, whereas its potential impact on alveolar cells remains inadequately explored. Metformin, a first-line drug for diabetes, has been shown to exert anti-inflammatory and tissue repair-promoting effects under various injurious conditions. Here, we explored the effect of chronic B[a]P exposure on alveolar cells and the impact of metformin on B[a]P-induced lung injury by examining the various parameters including lung histopathology, inflammation, fibrosis, and related signal pathway activation. MLKL knockout (Mlkl-/-) and AT2-lineage tracing mice (SftpcCre-ERT2;LSL-tdTomatoflox+/-) were used to delineate the role of necroptosis in B[a]P-induced alveolar epithelial injury and repair. Mice receiving weekly administration of B[a]P for 6 weeks developed a significant alveolar damaging phenotype associated with pulmonary inflammation, fibrosis, and activation of the necroptotic cell death pathway. These effects were significantly relieved in MLKL null mice. Furthermore, metformin treatment, which were found to promote AMPK phosphorylation and inhibit RIPK3, as well as MLKL phosphorylation, also significantly alleviated B[a]P-induced necroptosis and lung injury phenotype. However, the protective efficacy of metformin was rendered much less effective in Mlkl null mice or by blocking the necroptotic pathway with RIPK3 inhibitor. Our findings unravel a potential protective efficacy of metformin in mitigating the detrimental effects of B[a]P exposure on lung health by inhibiting necroptosis and protecting AT2 cells.

Metformin alleviates lung ischemia-reperfusion injury in a rat lung transplantation model

Background: Lung ischemia-reperfusion injury (LIRI) is among the complications observed after lung transplantation and is associated with morbidity and mortality. Preconditioning of the donor lung before organ retrieval may improve organ quality after transplantation. We investigated whether preconditioning with metformin (Met) ameliorates LIRI after lung transplantation. Methods: Twenty Lewis rats were randomly divided into the sham, LIRI, and Met groups. The rats in the LIRI and Met groups received saline and Met, respectively, via oral gavage. Subsequently, a donor lung was harvested and kept in cold storage for 8 h. The LIRI and Met groups then underwent left lung transplantation. After 2 h of reperfusion, serum and transplanted lung tissues were examined. Results: The partial pressure of oxygen (PaO2) was greater in the Met group than in the LIRI group. In the Met group, wet-to-dry (W/D) weight ratios, inflammatory factor levels, oxidative stress levels and apoptosis levels were notably decreased. Conclusions: Met protects against ischemia-reperfusion injury after lung transplantation in rats, and its therapeutic effect is associated with its anti-inflammatory, antioxidative, and antiapoptotic properties.

Protective role of metformin in preeclampsia via the regulation of NF-κB/sFlt-1 and Nrf2/HO-1 signaling pathways by activating AMPK

INTRODUCTION

Preeclampsia (PE) is a pregnancy complication that leads to hypertension and proteinuria and causes maternal mortality. Metformin (MET) is an oral hypoglycemic agent that activates AMPK-regulated signaling pathways and inhibits inflammation and oxidative stress responses. This study explored MET's roles and molecular mechanisms in PE.

METHODS

The protein or mRNA expression of signaling pathways and inflammation-related genes were detected by Western blotting and RT-qPCR and cell viability was analyzed with MTT. In addition, flow cytometry was used to assess apoptosis, and mitochondrial membrane potential was detected using JC-1 staining with flow cytometry. Moreover, LDH Cytotoxicity Assay Kit detected the release of LDH, and ROS, MDA, or SOD kits detected oxidative stress-related factors.

RESULTS

MET significantly inhibited inflammatory damage and oxidative stress responses in LPS-induced HTR-8/SVneo cells. Besides, MET could activate AMPK and then affect NF-κB/sFlt-1 and Nrf2/HO-1 signaling pathways in LPS-induced HTR-8/SVneo cells. Compound C (an AMPK inhibitor) significantly reversed MET's effects on LPS-stimulated HTR-8/SVneo cells.

DISCUSSION

MET attenuated inflammatory and oxidative stress of HTR-8/SVneo cells in PE by activating AMPK to regulate NF-κB/sFlt-1 and Nrf2/HO-1 signaling pathways, suggesting that MET was a potential therapeutic drug for PE.

Effects of metformin on acute respiratory distress syndrome in preclinical studies: a systematic review and meta-analysis

Introduction: In this study, we conducted a systematic review and meta-analysis to judge the effects of metformin on acute respiratory distress syndrome (ARDS) in a comprehensive and quantitative manner. Methods: We included studies that tested the effects of metformin on ALI or ARDS in in vivo studies. We excluded literature from which data could not be extracted or obtained. Electronic search was conducted to retrieve relevant literature from public databases, including PubMed, Web of Science, Embase, Scopus, and the Cochrane Central Register of Controlled Trials (inception to July 2023). Moreover, ProQuest Dissertations and Theses Global, Google Scholar, and Baidu scholar were inquired. Retrieved literature was screened and evaluated by pairs of reviewers independently according to pre-stated criteria. The Systematic Review Center for Laboratory Animal Experimentation risk of bias tool was used to evaluate the methodological quality of eligible literature. No restriction was exerted on publication status or language. Results: Fifteen preclinical studies were analyzed in this meta-analysis. Pooled results showed metformin effectively decreased pulmonary wet-to-dry weight ratios [SMD = -2.67 (-3.53 to -1.81), I2 = 56.6%], protein content [SMD = -3.74 (-6.76 to -0.72), I2 = 86.7%] and neutrophils [SMD = -3.47 (-4.69 to -2.26), I2 = 0%] in BALF, pulmonary malondialdehyde [SMD = -1.98 (-3.77 to -0.20), I2 = 74.2%] and myeloperoxidase activity [SMD = -3.15 (-4.79 to -1.52), I2 = 74.5%], lung injury scores [SMD = -4.19 (-5.65 to -2.74), I2 = 69.1%], and mortality at 24 h [RR = 0.43 (0.24-0.76), I2 = 0%] as well as 48 and 72 h. Conclusion: Metformin inhibited pulmonary inflammation and oxidative stress and improved experimental lung injury and survival rates in animal models of ARDS. Results from randomized controlled trials are needed.

HIF-1α promotes paraquat induced acute lung injury and implicates a role NF-κB and Rac2 activity

Paraquat (PQ) is a bipyridine herbicide and oral exposure is the main way of PQ exposure with a very high mortality. At present, it is believed that large number of oxygen free radicals are generated and cause lipid peroxidation of tissue and organ cell membranes after PQ is absorbed. PQ exposure could cause multiple organ dysfunction, among which acute lung injury is the most common and most serious. However, its specific mechanism is still unclear. In this study, the C57BL/6J mouse (alveolar epithelial cell-specific knockout HIF-1α) model of acute lung injury (40 mg/kg PQ) at several time pointes and a model of acute type II alveolar epithelial cell (A549, 800 μM PQ) injury constructed. The oxidative stress (ROS, MDA) and inflammatory response (IL-1β, IL-6, TNF-α) were significantly inhibited in the alveolar epithelial cell-specific knockout of HIF-1α mice and siRNA technology to inhibit HIF-1α in alveolar epithelial cells. Further proteomic analysis showed that the expression of Rac2 protein, which is closely related to oxidative stress, was significantly increased after PQ exposure. And the inhibition of Rac2 expression in vitro significantly alleviated PQ-induced oxidative stress and inflammatory response. The expression of Rac2 protein was regulated by HIF-1α. The above suggests that HIF-1α may promote oxidative stress and inflammatory response in alveolar epithelial cells by regulating the expression of Rac2, and then participate in the promotion of PQ exposure-induced acute lung injury.

Metformin antagonizes nickel-refining fumes-induced cell pyroptosis via Nrf2/GOLPH3 pathway in vitro and in vivo

Nickel compounds, an international carcinogen in the industrial environment, increased the risk of lung inflammation even lung cancer in Ni refinery workers. Metformin has displayed the intense anti-inflammation and anti-cancer properties through regulating pyroptosis. This study was designed to explore whether Nickel-refining fumes (NiRF) can induce cell pyroptosis and how AMPK/CREB/Nrf2 mediated the protection afforded by metformin against Ni particles-induced lung impairment. Our results represented that Ni fumes exposure evoked pyroptosis via GOLPH3 and induced oxidative stress, while, metformin treatment alleviated Ni particles-mediated above changes. Moreover, nuclear factor erythroid 2-related factor 2 (Nrf2) involved in the protection of metformin, and the deficiency of Nrf2 attenuated the beneficial protection. We also determined that Nrf2 was a downstream molecule of AMPK/CREB pathway. Furthermore, male C57BL/6 mice were administered with Ni at a dose of 2 mg/kg by non-exposed endotracheal instillation and metformin (100, 200 and 300 mg/kg) via oral gavage for 4 weeks. The results indicated that NiRF promoted GOLPH3 and pyroptosis by stimulating NLRP3, caspase-1, N-GSDMD, IL-18 and IL-1β expression. However, various doses of metformin reduced GOLPH3 and the above protein levels of pyroptosis, also improved AMPK/CREB/Nrf2 expression. In summary, we found that metformin suppressed NiRF-connected GOLPH3-prompted pyroptosis via AMPK/CREB/Nrf2 signaling pathway to confer pulmonary protection.

Potential Therapeutic Benefits of Metformin Alone and in Combination with Sitagliptin in the Management of Type 2 Diabetes Patients with COVID-19

Type 2 diabetes mellitus (T2DM) is a potential risk factor for the development of COVID-19 and is associated with higher severity and mortality rates. T2DM patients are commonly treated with metformin monotherapy or metformin plus sitagliptin. In the present case-control, single-center cohort study, a total number of 112 T2DM patients suffering from COVID-19 and aged 44−62 years old were compared with 78 T2DM patients without COVID-19 and aged 42−56 years old. Both the patient group and the control group were allocated into four groups. Group A: T2DM patients with COVID-19 on metformin treatments plus standard therapy (n = 60); group B: T2DM patients with COVID-19 on metformin plus sitagliptin plus standard therapy (n = 52); group C: T2DM patients without COVID-19 on metformin treatments (n = 40); and group D: T2DM patients without COVID-19 on metformin plus sitagliptin (n = 38). The investigation duration was 2−3 weeks. Anthropometric measurements, serological and biochemical investigations, pulmonary radiological findings, and clinical outcomes were evaluated. Only 101 T2DM patients with COVID-19 continued the study, 71 (70.29%) with mild-moderate COVID-19 and 30 (29.7%) with severe COVID-19 were compared with 78 T2DM patients as a control. Inflammatory biomarkers (C reactive protein, ferritin, and procalcitonin), a lung injury biomarker (lactate dehydrogenase), and a coagulopathy biomarker (D-dimer) were elevated in severe COVID-19 patients compared with mild-moderate COVID-19 (p < 0.05) and T2DM patients (p < 0.05). However, metformin plus sitagliptin was more effective than metformin monotherapy in T2DM patients with COVID-19, as evidenced by the mitigation of oxidative stress, CT scan score, and clinical outcomes. The present study confirmed the protective effects of this combination against the development of COVID-19 severity, as most T2DM COVID-19 patients develop mild-moderate forms. Herein, the combination of metformin and sitagliptin may lead to more beneficial effects than metformin monotherapy.

Combination therapy with budesonide and N-acetylcysteine ameliorates LPS-induced ALI by attenuating neutrophil recruitment through the miR-196b-5p/Socs3 molecular axis

Background

Neutrophil infiltration accelerates the inflammatory response and is highly correlated to the development of acute lung injury (ALI). Budesonide (BUD) and N-acetylcysteine (NAC) both inhibit the inflammatory response to alleviate ALI, so we further investigated whether their combination is better for ALI.

Methods

In this study, we investigated the effect and mechanism of Combined BUD and NAC therapy on LPS-induced ALI. Rat ALI model and neutrophil abnormal activation model were established by lipopolysaccharide (LPS). BUD and NAC were treated alone or in combination, or cells were transfected with miR-196b-5p mimic or si-Socs3 to evaluate the efficacy and mechanism of BUD and NAC alone or in combination. Histopathological observation of lungs was performed by Hematoxylin Eosin (HE) staining. The quantity of neutrophils and inflammatory factors level in bronchoalveolar lavage fluid (BALF) were determined by Richter-Gimza complex stain and Enzyme-Linked Immunosorbnent Assay (ELISA), respectively. ReverseTranscription-PolymeraseChainReaction (RT–qPCR) was utilized to assess miR-196b-5p and inflammatory factor mRNA levels. The expression level of Socs3 was detected by immunohistochemistry or Western Blot.

Results

BUD and NAC combined treatment had a better effect on neutrophil recruitment and inflammatory response in LPS-induced ALI than did BUD and NAC alone. Transfection of the miR-196b-5p mimic reversed the effect of combined BUD and NAC. In conclusion, the combination of BUD and NAC is a better treatment for ALI.

Conclusions

Combination therapy with BUD and NAC ameliorates LPS-induced ALI by attenuating neutrophil recruitment through the miR-196b-5p/Socs3 molecular axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02185-7.

Obligatory Role of AMPK Activation and Antioxidant Defense Pathway in the Regulatory Effects of Metformin on Cellular Protection and Prevention of Lens Opacity

Increasing levels of oxidative-stress due to deterioration of the Nrf2 (NFE2-related factor)/ARE (antioxidant response element) pathway is found to be a primary cause of aging pathobiology. Metformin having anti-aging effects can delay/halt aging-related diseases. Herein, using lens epithelial cell lines (LECs) of human (h) or mouse (m) and aging h/m primary LECs along with lenses as model systems, we demonstrated that Metformin could correct deteriorated Bmal1/Nrf2/ARE pathway by reviving AMPK-activation, and transcriptional activities of Bmal1/Nrf2, resulting in increased antioxidants enzymatic activity and expression of Phase II enzymes. This ensued reactive oxygen species (ROS) mitigation with cytoprotection and prevention of lens opacity in response to aging/oxidative stress. It was intriguing to observe that Metformin internalized lens/LECs and upregulated OCTs (Organic Cation Transporters). Mechanistically, we found that Metformin evoked AMPK activation-dependent increase of Bmal1, Nrf2, and antioxidants transcription by promoting direct E-Box and ARE binding of Bmal1 and Nrf2 to the promoters. Loss-of-function and disruption of E-Box/ARE identified that Metformin acted by increasing Bmal1/Nrf2-mediated antioxidant expression. Data showed that AMPK-activation was a requisite for Bmal1/Nrf2-antioxidants-mediated defense, as pharmacologically inactivating AMPK impeded the Metformin's effect. Collectively, the results for the first-time shed light on the hitherto incompletely uncovered crosstalk between the AMPK and Bmal1/Nrf2/antioxidants mediated by Metformin for blunting oxidative/aging-linked pathobiology.

4,7-Didehydro-neophysalin B Protects Rat Lung Epithelial Cells against Hydrogen Peroxide-Induced Oxidative Damage through Nrf2-Mediated Signaling Pathway

The administration of 4,7-didehydro-neophysalin B is expected to be a promising strategy for mitigating oxidative stress in respiratory diseases. This study was aimed at investigating the efficacy of 4,7-didehydro-neophysalin B for apoptosis resistance of rat lung epithelial cells (RLE-6TN) to oxidative stress and evaluating its underlying mechanism of action. The RLE-6TN cells treated with hydrogen peroxide (H₂O₂) were divided into five groups, and 4,7-didehydro-neophysalin B was administered into it. To evaluate its mechanism of action, the expression of oxidative stress and apoptotic proteins was investigated. 4,7-Didehydro-neophysalin B significantly inhibited H₂O₂-induced RLE-6TN cell damage. It also activated the Nrf2 signaling pathway which was evident from the increased transcription of antioxidant responsive of KLF9, NQO1, Keap-1, and HO-1. Nrf2 was found to be a potential target of 4,7-didehydro-neophysalin B. The protein levels of Bcl-2 and Bcl-xL were increased while Bax and p53 were decreased significantly. Flow cytometry showed that 4,7-didehydro-neophysalin B protected RLE-6TN cells from apoptosis and has improved the oxidative damage. This study provided a promising evidence that 4,7-didehydro-neophysalin B can be a therapeutic option for oxidative stress in respiratory diseases.

Arsenic induces ferroptosis and acute lung injury through mtROS-mediated mitochondria-associated endoplasmic reticulum membrane dysfunction

The goal of this study was to analyze whether mitochondria-associated endoplasmic reticulum membrane (MAMs) dysfunction mediated arsenic (As)-evoked pulmonary ferroptosis and acute lung injury (ALI). As exposure led to alveolar structure damage, inflammatory cell infiltration and pulmonary function decline in mice. Ferritin, the marker of iron overload, was increased, GPX4, the index of lipid peroxidation, was decreased in As-exposed lungs and pulmonary epithelial cells (MLE-12). Pretreatment with ferrostatin-1 (Fer-1), the inhibitor of ferroptosis, alleviated As-evoked ALI. In addition, As-induced non-heme iron deposition was inhibited in Fer-1 pretreated-mice. Moreover, As-triggered mitochondria damage and ferroptosis were mitigated in Fer-1 pretreated-MLE-12 cells. Mechanistically, PERK phosphorylation and mitofusin-2 (Mfn-2) reduction was observed in As-exposed MLE-12 cells and mice lungs. Additionally, the interaction between PERK and Mfn-2 was downregulated and MAMs dysfunction was observed in As-exposed MLE-12 cells. Intriguingly, PERK inhibitor and Mfn-2-overexpression all mitigated As-induced ferroptosis in MLE-12 cells. Additionally, CLPP and mtHSP70, the markers of mitochondrial stress, were upregulated, mitochondrial ROS (mtROS) was elevated, mitochondrial membrane potential (MMP) and ATP were decreased in As-exposed MLE-12 cells. Mitoquinone mesylate (MitoQ), a novel mitochondrial-targeted antioxidant, alleviated As-induced excess mtROS, mitochondrial stress, MAMs dysfunction in pulmonary epithelial cells. Similarly, in vivo experiments indicated that MitoQ pretreatment countered As-induced pulmonary ferroptosis and ALI. These data indicated that mtROS-initiated MAMs dysfunction is, at least partially, implicated in As-evoked ferroptosis and ALI.

Ginkgolide C Alleviates Acute Lung Injury Caused by Paraquat Poisoning via Regulating the Nrf2 and NF-κB Signaling Pathways

Paraquat (PQ), a highly toxic herbicide and primary attack for lung, results in severe acute lung injury (ALI) appeared as evident oxidative stress, inflammation, and apoptosis. Increasing evidence elucidates that nuclear factor erythroid-2-related factor 2 (Nrf2) and its associated nuclear factor-κB (NF-κB) exhibit many merits for protection of ALI by coordinating a fine-turned response to oxidative stress, inflammation, and apoptosis. Ginkgolide C (GC) has been reported to be a safe and potent therapeutic agent against ALI. However, whether GC could protect ALI induced by PQ poisoning and the possible underlining mechanisms have remained not to be fully elucidated. A rat model of ALI and a model of acute type II alveolar epithelial cell (RLE-6TN) injury constructed by exposure to PQ were applied to discuss the protective effect of GC. Furthermore, Nrf2 gene silencing RLE-6TN cells were used to discuss the exact mechanism. We confirmed that GC significantly ameliorated the histopathological damages, ultrastructural changes, lung injury score, W/D ratio, and Hyp activity of lung tissue and inhibited polymorphonuclear neutrophil (PMN) infiltration after PQ poisoning. Further results revealed that GC remarkably activated Nrf2-based cytoprotective system and inhibited NF-κB-induced inflammatory injury as well as apoptosis. Taken together, we concluded that GC preserved protection of PQ-induced ALI via the Nrf2-NF-κB dependent signal pathway, which may provide us novel insights into the treatment strategies for PQ poisoning.

Metformin Regulates Alveolar Macrophage Polarization to Protect Against Acute Lung Injury in Rats Caused by Paraquat Poisoning

This study explored the role of metformin (MET) in regulating the polarization of alveolar macrophages to protect against acute lung injury (ALI) in rats caused by paraquat (PQ) poisoning. The in vivo studies showed that the 35 mg/kg dose of MET increased the survival rate of rats, alleviated pathological damages to the lungs and their systemic inflammation, promoted the reduction of the pro-inflammatory factors interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels, and increased the anti-inflammatory factor IL-10 levels in the rat serum. At the same time, the MET intervention decreased the expression of M1 macrophage marker iNOS in the lungs of the PQ-poisoned rats while increasing the M2 macrophage marker, Arg1, expression. In vitro, the concentration of MET > 10 mmol/L affected NR8383 viability adversely and was concentration-dependent; however, no adverse impact on NR8383 viability was observed at MET ≤ 10 mmol/L concentration, resisting the reducing effect of PQ on NR8383 vitality. The PQ-induced NR8383 model with MET intervention showed significantly reduced secretions of IL-6 and TNF-α in NR8383, and lowered expressions of M1 macrophage markers iNOS and CD86. Additionally, MET increased IL-10 secretion and the M2 macrophage markers, Arg1 and Mrcl, expressions. Therefore, we speculate that MET could regulate alveolar macrophage polarization to protect against PQ-poisoning caused ALI.

Metformin alleviates nickel-refining fumes-induced aerobic glycolysis via AMPK/GOLPH3 pathway in vitro and in vivo

Nickel (Ni) compounds is recognized industrial carcinogen, which could increase the risk of lung cancer in Ni refineries workers. However, the underlying carcinogenic mechanism still remains to elucidate. Metformin has shown the anticancer properties through suppressing aerobic glycolysis. In the present study, we evaluated the effect of Ni-refining fumes exposure on aerobic glycolysis and the role of AMPK/GOLPH3, as well as how metformin alleviated nickel-induced aerobic glycolysis in vitro and vivo. Firstly, Beas-2B cells were exposed to different concentrations of Ni-refining fumes and pretreated with metformin (activation of AMPK), compound C (AMPK inhibitor) in vitro. Our findings indicated that Ni fumes expose evoked aerobic glycolysis by AMPK/GOLPH3, while metformin attenuated Ni particles-promoted GOLPH3-mediated aerobic glycolysis by p-AMPK expression increase. Then Mito-TEMPT (a mitochondria-targeted antioxidant) and lipopolysaccharide (LPS, ROS activator) were pretreated to affect ROS production in Beas-2B cells. Ni-induced ROS prevented AMPK activation. Moreover, C57BL/6 mice were exposed to 2 mg/kg Ni by non-exposed endotracheal instillation and metformin (100, 200 and 300 mg/kg) via oral gavage for 4 weeks. The effects of AMPK/GOLPH3 axis on Ni-induced aerobic glycolysis were assessed. The results indicated that metformin decreased the protein levels of GOLPH3, LDHA, HK2, MCT-4 and improved p-AMPK expression. Thus, our findings demonstrated metformin antagonized Ni-refining fumes-caused aerobic glycolysis via AMPK/GOLPH3.

Environmental relevant herbicide prometryn induces developmental toxicity in the early life stages of marine medaka (Oryzias melastigma) and its potential mechanism

Triazine herbicides have been widely detected in marine environments because of their extensive usage in agriculture, but their impact on marine organisms is unclear. In this study, marine medaka (Oryzias melastigma) embryos were exposed to 0, 1, 10, 100, and 1000 μg/L prometryn, one of the most detected triazine herbicides, to investigate its potential effects. The results showed that 1, 10, 100, and 1000 µg/L prometryn not only induced yolk sac shrinkage and heart malformations, but also significantly delayed the hatching time and increased the heart rate and hatching failure rate of embryos. Moreover, 1, 10, 100, and 1000 μg/L prometryn caused obvious malformations and decreased the body length of the newly hatched larvae. After 21 d of exposure, increased larval death rate, decreased body length and width, and higher lipid accumulation were observed in the larvae from all prometryn groups. Furthermore, prometryn exposure upregulated the expression levels of cardiac development-related genes GATA, COX, ATPase, SmyD1, EPO, FGF8, NKX2, and BMP4 in the larvae. Transcriptome analysis revealed that 10 μg/L prometryn upregulated 604 genes, and the topmost pathways of differentially expressed genes were the complement and coagulation cascades and AMPK signaling pathways. qPCR results confirmed that prometryn exposure significantly increased the expression levels of the complement and coagulation cascade genes f2, f5, c3, and c5. This study demonstrated that environmentally relevant concentrations of prometryn induced significant toxicity in the early life stages of marine medaka. Therefore, the health risks of herbicides to marine organisms are of great concern.

Metformin Ameliorates Inflammation and Airway Remodeling of Experimental Allergic Asthma in Mice by Restoring AMPKα Activity

Metformin has been involved in modulating inflammatory state and inhibiting cell proliferation and angiogenesis. This study aimed to determine whether metformin alleviates airway inflammation and remodeling of experimental allergic asthma and elucidate the underlying mechanism. We sensitized and challenged mice with ovalbumin (OVA) to induce allergic asthma. During the challenge period, metformin was administered by intraperitoneal injection. By histopathological and immunohistochemical analyses, metformin-treated mice showed a significant alleviation in airway inflammation, and in the parameters of airway remodeling including goblet cell hyperplasia, collagen deposition and airway smooth muscle hypertrophy compared to those in the OVA-challenged mice. We also observed elevated levels of multiple cytokines (IL-4, IL-5, IL-13, TNF-α, TGF-β1 and MMP-9) in the bronchoalveolar lavage fluid, OVA-specific IgE in the serum and angiogenesis-related factors (VEGF, SDF-1 and CXCR4) in the plasma from asthmatic mice, while metformin reduced all these parameters. Additionally, the activity of 5′-adenosine monophosphate-activated protein kinase a (AMPKα) in the lungs from OVA-challenged mice was remarkably lower than control ones, while after metformin treatment, the ratio of p-AMPKα to AMPKα was upregulated and new blood vessels in the sub-epithelial area as evidenced by CD31 staining were effectively suppressed. These results indicate that metformin ameliorates airway inflammation and remodeling in an OVA-induced chronic asthmatic model and its protective role could be associated with the restoration of AMPKα activity and decreased asthma-related angiogenesis.

Anthrahydroquinone-2-6-disulfonate is a novel, powerful antidote for paraquat poisoning

Paraquat (PQ) is a widely used fast-acting pyridine herbicide. Accidental ingestion or self-administration via various routes can cause severe organ damage. Currently, no effective antidote is available commercially, and the mortality rate of poisoned patients is exceptionally high. Here, the efficacy of anthrahydroquinone-2-6-disulfonate (AH₂QDS) was observed in treating PQ poisoning by constructing in vivo and ex vivo models. We then explored the detoxification mechanism of AH₂QDS. We demonstrated that, in a rat model, the PQ concentration in the PQ + AH₂QDS group significantly decreased compared to the PQ only group. Additionally, AH₂QDS protected the mitochondria of rats and A549 cells and decreased oxidative stress damage, thus improving animal survival and cell viability. Finally, the differentially expressed genes were analysed in the PQ + AH₂QDS group and the PQ group by NextGen sequencing, and we verified that Nrf2's expression in the PQ + AH₂QDS group was significantly higher than that in the PQ group. Our work identified that AH₂QDS can detoxify PQ by reducing PQ uptake and protecting mitochondria while enhancing the body's antioxidant activity.

Il12a Deletion Aggravates Sepsis-Induced Cardiac Dysfunction by Regulating Macrophage Polarization

Cardiac dysfunction is a well-recognized complication of sepsis and is associated with the outcome and prognosis of septic patients. Evidence suggests that Il12a participates in the regulation of various cardiovascular diseases, including heart failure, hypertension and acute myocardial infarction. However, the effects of Il12a in sepsis-induced cardiac dysfunction remain unknown. In our study, lipopolysaccharide (LPS) and cecal ligation and puncture (CLP) model were used to mimic sepsis, and cardiac Il12a expression was assessed. In addition, Il12a knockout mice were used to detect the role of Il12a in sepsis-related cardiac dysfunction. We observed for the first time that Il12a expression is upregulated in mice after LPS treatment and macrophages were the main sources of Il12a. In addition, our findings demonstrated that Il12a deletion aggravates LPS-induced cardiac dysfunction and injury, as evidenced by the increased serum and cardiac levels of lactate dehydrogenase (LDH) and cardiac creatine kinase-myocardial band (CK-MB). Moreover, Il12a deletion enhances LPS-induced macrophage accumulation and drives macrophages toward the M1 phenotype in LPS-treated mice. Il12a deletion also downregulated the activity of AMP-activated protein kinase (AMPK) but increased the phosphorylation levels of p65 (p-p65) and NF-κB inhibitor alpha (p-IκBα). In addition, Il12a deletion aggravates CLP-induced cardiac dysfunction and injury. Treatment with the AMPK activator AICAR abolishes the deterioration effect of Il12a deletion on LPS-induced cardiac dysfunction. In conclusion, Il12a deletion aggravated LPS-induced cardiac dysfunction and injury by exacerbating the imbalance of M1 and M2 macrophages. Our data provide evidence that Il12a may represent an attractive target for sepsis-induced cardiac dysfunction.

Comparison of Pancreatic Damage in Rats for Two Methods of Paraquat Administration

It is noted that elevated serum amylase levels suggesting pancreatic damage has an association with prognosis in PQ patients. This study aimed to determine whether PQ can cause pancreatic damage. The two conventional models (intragastric infusion (iG) and intraperitoneal injection (iP)) may exhibit different effects on the pancreas depending on whether or not they pass through the digestive tract. In this study, the rats were divided into four groups: the intragastric infusion group (PQ-iG, n = 45), intraperitoneal injection group (PQ-iP, n = 53), normal control group 1 (NC-iG, n = 6) and normal control group 2 (NC-iP, n = 6). Pancreatic damage was compared between groups using serum amylase activity assay, hematoxylin and eosin (H&E) staining, TUNEL assay, and transmission electron microscopy (TEM). Serum amylase levels in group PQ-iG were significantly higher than in group PQ-iP (p < 0.05). Examination of the H&E sections showed damage to the pancreas. Both experimental groups were displayed inflammatory infiltration within 9 h of PQ treatment. After 9 h, patchy necrosis was observed in group PQ-iP, when inflammatory infiltration was still the dominant pathology. Necrosis appeared and gradually worsened in group PQ-iG, in which necrosis was the dominant pathology. The TUNEL assay showed significantly higher numbers of apoptotic cells in the pancreas of PQ-groups than in the control NC- groups (p < 0.05). TEM showed expansive endoplasmic reticulum lumens and mitochondria swelling in the pancreas of the PQ-groups. It is concluded that both methods of modeling could cause pancreatic damage and the type and degree of damage would change over time. Note that pancreatic damage in group PQ-iG was more severe than that in group PQ-iP. Therefore, clinical practitioners should pay close attention to pancreatic damage caused by PQ, especially when the route of PQ administration was oral.

Oxidative Imbalance as a Crucial Factor in Inflammatory Lung Diseases: Could Antioxidant Treatment Constitute a New Therapeutic Strategy?

Inflammatory lung disease results in a high global burden of death and disability. There are no effective treatments for the most severe forms of many inflammatory lung diseases, such as chronic obstructive pulmonary disease, emphysema, corticosteroid-resistant asthma, and coronavirus disease 2019; hence, new treatment options are required. Here, we review the role of oxidative imbalance in the development of difficult-to-treat inflammatory lung diseases. The inflammation-induced overproduction of reactive oxygen species (ROS) means that endogenous antioxidants may not be sufficient to prevent oxidative damage, resulting in an oxidative imbalance in the lung. In turn, intracellular signaling events trigger the production of proinflammatory mediators that perpetuate and aggravate the inflammatory response and may lead to tissue damage. The production of high levels of ROS in inflammatory lung diseases can induce the phosphorylation of mitogen-activated protein kinases, the inactivation of phosphoinositide 3-kinase (PI3K) signaling and histone deacetylase 2, a decrease in glucocorticoid binding to its receptor, and thus resistance to glucocorticoid treatment. Hence, antioxidant treatment might be a therapeutic option for inflammatory lung diseases. Preclinical studies have shown that antioxidants (alone or combined with anti-inflammatory drugs) are effective in the treatment of inflammatory lung diseases, although the clinical evidence of efficacy is weaker. Despite the high level of evidence for the efficacy of antioxidants in the treatment of inflammatory lung diseases, the discovery and clinical investigation of safer, more efficacious compounds are now a priority.

Thal protects against paraquat-induced lung injury through a microRNA-141/HDAC6/IκBα-NF-κB axis in rat and cell models

The protective functions of thalidomide in paraquat (PQ)-induced injury have been reported. But the mechanisms remain largely unknown. In this research, a PQ-treated rat model was established and further treated with thalidomide. Oedema and pathological changes, oxidative stress, inflammation, fibrosis and cell apoptosis in rat lungs were detected. A PQ-treated RLE-6TN cell model was constructed, and the viability and apoptosis rate of cells were measured. Differentially expressed microRNAs (miRNAs) after thalidomide administration were screened out. Binding relationship between miR-141 and histone deacetylase 6 (HDAC6) was validated. Altered expression of miR-141 and HDAC6 was introduced to identify their involvements in thalidomide-mediated events. Consequently, thalidomide administration alone exerted no damage to rat lungs; in addition it reduced PQ-induced oedema. The oxidative stress, inflammation and cell apoptosis in rat lungs were reduced by thalidomide. In RLE-6TN cells, thalidomide increased cell viability and decreased apoptosis. miR-141 was responsible for thalidomide-mediated protective events by targeting HDAC6. Overexpression of HDAC6 blocked the protection of thalidomide against PQ-induced injury via activating the IkBα-NF-κB signalling pathway. Collectively, this study evidenced that thalidomide protects lung tissues from PQ-induced injury through a miR-141/HDAC6/IkBα-NF-κB axis.

A novel simple risk model to predict the prognosis of patients with paraquat poisoning

To identify risk factors and develop a simple model to predict early prognosis of acute paraquat (PQ) poisoning patients, we performed a retrospective cohort study of acute PQ poisoning patients (n = 1199). Patients (n = 913) with PQ poisoning from 2011 to 2018 were randomly divided into training (n = 609) and test (n = 304) samples. Another two independent cohorts were used as validation samples for a different time (n = 207) and site (n = 79). Risk factors were identified using a logistic model with Markov Chain Monte Carlo (MCMC) simulation and further evaluated using a latent class analysis. The prediction score was developed based on the training sample and was evaluated using the testing and validation samples. Eight factors, including age, ingestion volume, creatine kinase-MB [CK-MB], platelet [PLT], white blood cell [WBC], neutrophil counts [N], gamma-glutamyl transferase [GGT], and serum creatinine [Cr] were identified as independent risk indicators of in-hospital death events. The risk model had C statistics of 0.895 (95% CI 0.855-0.928), 0.891 (95% CI 0.848-0.932), and 0.829 (95% CI 0.455-1.000), and predictive ranges of 4.6-98.2%, 2.3-94.9%, and 0-12.5% for the test, validation_time, and validation_site samples, respectively. In the training sample, the risk model classified 18.4%, 59.9%, and 21.7% of patients into the high-, average-, and low-risk groups, with corresponding probabilities of 0.985, 0.365, and 0.03 for in-hospital death events. We developed and evaluated a simple risk model to predict the prognosis of patients with acute PQ poisoning. This risk scoring system could be helpful for identifying high-risk patients and reducing mortality due to PQ poisoning.

Metformin attenuates lipopolysaccharide-induced epithelial cell senescence by activating autophagy

Acute lung injury (ALI) is a life-threatening medical condition with higher mortality and morbidity in elderly patients. Recently, metformin, a drug commonly used to lower blood glucose in type 2 diabetes patients, has been shown to be an effective anti-inflammatory agent in ALI. However, the mechanism of this regulation still remains poorly understood. In our study, we found that epithelial cell senescence was elevated after lipopolysaccharide (LPS) exposure in vivo and in vitro, accompanied by decreased expression of ATG5 and impaired autophagy activity. To further discover the molecular regulation mechanism between cellular senescence and autophagy in LPS-treated MLE-12 cells, we demonstrated that inhibition of ATG5 could decrease autophagy levels and promote the senescence of MLE-12 cells. On the contrary, elevating the expression of ATG5 could effectively suppress LPS-induced cellular senescence via enhancing autophagy activity. In addition, we demonstrated that metformin could protect MLE-12 cells from LPS-induced senescence via increasing the expression of ATG5 and augmenting autophagy activity. Our data implicate that activation of autophagy by metformin may provide a preventive and therapeutic strategy for ALI.

Protective effect of toll-interacting protein overexpression against paraquat-induced lung injury in mice and A549 cells through inhibiting oxidative stress, inflammation, and NF-κB signaling pathway

Toll-interacting protein (Tollip) is a pivotal negative regulator of inflammatory response. In the present study, the effects of Tollip overexpression on paraquat (PQ)-induced lung injury were explored through in vivo and in vitro investigations. Upon stimulation with PQ in mice, the expression of Tollip was down-regulated. Histopathological analysis revealed that the overexpression of Tollip significantly decreased inflammatory cell infiltration. Similarly, the levels of myeloperoxidase (MPO) and interleukin-1β (IL-1β) were lowered by Tollip overexpression in PQ-administrated mice. Besides, the overexpression of Tollip reduced reactive oxygen species (ROS) generation and malondialdehyde (MDA) level but enhanced superoxide dismutase (SOD) activity in PQ-treated A549 cells. Meanwhile, Tollip overexpression lowered the level of IL-1β and decreased the protein expressions of p-p65 in the cytoplasm and nuclear p65. Importantly, inhibition of NF-κB signaling pathway probably by decreasing NF-κB p65-DNA binding activity was induced by Tollip overexpression. Taken together, Tollip overexpression attenuated PQ-initiated lung injury possibly via reduction of oxidative stress and inflammation and suppression of NF-κB signaling pathway activation, which provided some novel ideas for the treatment of lung damage mediated by PQ.

Immunomodulatory and Antiviral Activity of Metformin and Its Potential Implications in Treating Coronavirus Disease 2019 and Lung Injury

The pandemic of coronavirus disease 2019 (COVID-19), a disease which causes severe lung injury and multiple organ damage, presents an urgent need for new drugs. The case severity and fatality of COVID-19 are associated with excessive inflammation, namely, a cytokine storm. Metformin, a widely used drug to treat type 2 diabetes (T2D) mellitus and metabolic syndrome, has immunomodulatory activity that reduces the production of proinflammatory cytokines using macrophages and causes the formation of neutrophil extracellular traps (NETs). Metformin also inhibits the cytokine production of pathogenic Th1 and Th17 cells. Importantly, treatment with metformin alleviates various lung injuries in preclinical animal models. In addition, a recent proteomic study revealed that metformin has the potential to directly inhibit SARS-CoV-2 infection. Furthermore, retrospective clinical studies have revealed that metformin treatment reduces the mortality of T2D with COVID-19. Therefore, metformin has the potential to be repurposed to treat patients with COVID-19 at risk of developing severe illness. This review summarizes the immune pathogenesis of SARS-CoV-2 and addresses the effects of metformin on inhibiting cytokine storms and preventing SARS-CoV-2 infection, as well as its side effects.