Inhibition of glycolysis alleviates lipopolysaccharide‐induced acute lung injury in a mouse model

Endogenous drivers of altered immune cell metabolism

Dysregulated metabolism has long been recognized as a feature of many metabolic disorders. However, recent studies demonstrating that metabolic reprogramming occurs in immune cells have led to a growing interest in the relationship between metabolic rewiring and immune-mediated disease pathogeneses. It is clear now that immune cell subsets engage in different metabolic pathways depending on their activation and/or maturation state. As a result, it may be possible to modulate metabolic reprogramming for clinical benefit. In this review, we provide an overview of immune cell metabolism with focus on endogenous drivers of metabolic reprogramming given their link to a number of immune-mediated disorders.

Mitochondrial citrate accumulation drives alveolar epithelial cell necroptosis in lipopolysaccharide-induced acute lung injury

Necroptosis is the major cause of death in alveolar epithelial cells (AECs) during acute lung injury (ALI). Here, we report a previously unrecognized mechanism for necroptosis. We found an accumulation of mitochondrial citrate (citrate^mt) in lipopolysaccharide (LPS)-treated AECs because of the downregulation of Idh3α and citrate carrier (CIC, also known as Slc25a1). shRNA- or inhibitor-mediated inhibition of Idh3α and Slc25a1 induced citrate^mt accumulation and necroptosis in vitro. Mice with AEC-specific Idh3α and Slc25a1 deficiency exhibited exacerbated lung injury and AEC necroptosis. Interestingly, the overexpression of Idh3α and Slc25a1 decreased citrate^mt levels and rescued AECs from necroptosis. Mechanistically, citrate^mt accumulation induced mitochondrial fission and excessive mitophagy in AECs. Furthermore, citrate^mt directly interacted with FUN14 domain-containing protein 1 (FUNDC1) and promoted the interaction of FUNDC1 with dynamin-related protein 1 (DRP1), leading to excessive mitophagy-mediated necroptosis and thereby initiating and promoting ALI. Importantly, necroptosis induced by citrate^mt accumulation was inhibited in FUNDC1-knockout AECs. We show that citrate^mt accumulation is a novel target for protection against ALI involving necroptosis.

How location and cellular signaling combine to activate the NLRP3 inflammasome

NOD-, LRR-, and pyrin domain-containing 3 (NLRP3) is a cytosolic innate immune sensor of cellular stress signals, triggered by infection and sterile inflammation. Upon detection of an activating stimulus, NLRP3 transitions from an inactive homo-oligomeric multimer into an active multimeric inflammasome, which promotes the helical oligomeric assembly of the adaptor molecule ASC. ASC oligomers provide a platform for caspase-1 activation, leading to the proteolytic cleavage and activation of proinflammatory cytokines in the IL-1 family and gasdermin D, which can induce a lytic form of cell death. Recent studies investigating both the cellular requirement for NLRP3 activation and the structure of NLRP3 have revealed the complex regulation of NLRP3 and the multiple steps involved in its activation. This review presents a perspective on the biochemical and cellular processes controlling the assembly of the NLRP3 inflammasome with particular emphasis on structural regulation and the role of organelles. We also highlight the latest research on metabolic control of this inflammatory pathway and discuss promising clinical targets for intervention.

Role of metabolic reprogramming in pro-inflammatory cytokine secretion from LPS or silica-activated macrophages

In the lungs, macrophages constitute the first line of defense against pathogens and foreign bodies and play a fundamental role in maintaining tissue homeostasis. Activated macrophages show altered immunometabolism and metabolic changes governing immune effector mechanisms, such as cytokine secretion characterizing their classic (M1) or alternative (M2) activation. Lipopolysaccharide (LPS)-stimulated macrophages demonstrate enhanced glycolysis, blocked succinate dehydrogenase (SDH), and increased secretion of interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α). Glycolysis suppression using 2 deoxyglucose in LPS-stimulated macrophages inhibits IL-1β secretion, but not TNF-α, indicating metabolic pathway specificity that determines cytokine production. In contrast to LPS, the nature of the immunometabolic responses induced by non-organic particles, such as silica, in macrophages, its contribution to cytokine specification, and disease pathogenesis are not well understood. Silica-stimulated macrophages activate pattern recognition receptors (PRRs) and NLRP3 inflammasome and release IL-1β, TNF-α, and interferons, which are the key mediators of silicosis pathogenesis. In contrast to bacteria, silica particles cannot be degraded, and the persistent macrophage activation results in an increased NADPH oxidase (Phox) activation and mitochondrial reactive oxygen species (ROS) production, ultimately leading to macrophage death and release of silica particles that perpetuate inflammation. In this manuscript, we reviewed the effects of silica on macrophage mitochondrial respiration and central carbon metabolism determining cytokine specification responsible for the sustained inflammatory responses in the lungs.

Epoxyeicosatrienoic Acids Inhibit the Activation of Murine Fibroblasts by Blocking the TGF-β1-Smad2/3 Signaling in a PPARγ-Dependent Manner

Background

Epoxyeicosatrienoic acids (EETs), the metabolite of arachidonic acid by cytochrome P450 (CYP), reportedly serve as a vital endogenous protective factor in several chronic diseases. EETs are metabolized by soluble epoxide hydrolase (sEH). We have observed that prophylactic blocking sEH alleviates bleomycin- (BLM-) induced pulmonary fibrosis (PF) in mice. However, the underlying mechanism and therapeutic effects of EETs on PF remain elusive.

Objective

In this study, we investigated the effect of CYP2J2/EETs on the activation of murine fibroblasts and their mechanisms.

Results

we found that administration of the sEH inhibitor (TPPU) 7 days after the BLM injection also reversed the morphology changes and collagen deposition in the lungs of BLM-treated mice, attenuating PF. Fibroblast activation is regarded as a critical role of PF. Therefore, we investigated the effects of EETs on the proliferation and differentiation of murine fibroblasts. Results showed that the overexpression of CYP2J2 reduced the cell proliferation and the expressions of α-SMA and PCNA induced by transforming growth factor- (TGF-) β1 in murine fibroblasts. Then, we found that EETs inhibited the proliferation and differentiation of TGF-β1-treated-NIH3T3 cells and primary murine fibroblasts. Mechanistically, we found that 14,15-EET disrupted the phosphorylation of Smad2/3 murine fibroblasts by activating PPARγ, which was completely abolished by a PPARγ inhibitor GW9662.

Conclusion

our study shows that EETs inhibit the activation of murine fibroblasts by blocking the TGF-β1-Smad2/3 signaling in a PPARγ-dependent manner. Regulating CYP2J2-EET-sEH metabolic pathway may be a potential therapeutic option in PF.

N-phenethyl-5-phenylpicolinamide alleviates inflammation in acute lung injury by inhibiting HIF-1α/glycolysis/ASIC1a pathway

AIMS

Acute lung injury (ALI) is triggered by an acute inflammatory response. Lipopolysaccharide (LPS) is recognized as an important participant in the pathogenesis of sepsis, which may induce ALI. N-phenethyl-5-phenylpicolinamide (N5P) is a newly synthesized HIF-1α inhibitor. The purpose of the present study was to investigate the potential protective effects of N5P on LPS-induced ALI and the underlying mechanisms.

MAIN METHODS

In vivo experiment, the ALI rat model was induced by intratracheal injection of LPS, and various concentrations of N5P were injected intraperitoneally before LPS administration. In vitro experiment, RAW264.7 macrophages were administrated LPS and N5P to detect inflammatory cytokine changes. HIF-1α overexpression plasmid (HIF1α-OE) and granulocyte-macrophage colony-stimulating factor (GM-CSF), a glycolysis agonist, were used to examine the relationship between the HIF-1α/glycolysis/ASIC1a pathway.

KEY FINDINGS

Pretreatment with N5P inhibited not only the histopathological changes that occurred in the lungs but also lung dysfunction in LPS-induced ALI. N5P also decreased the levels of lactic acid in lung tissue and arterial blood, and inflammatory factors IL-1β and IL-6 levels in serum. LPS increased HIF-1α, glycolysis proteins GLUT1, HK2, ASIC1a, IL-1β, IL-6, and these changes were reversed by N5P in primary alveolar macrophages and RAW264.7 macrophages. Overexpression of HIF-1α significantly increased glycolysis genes and ASIC1a as well as inflammatory cytokines. Excessive glycolysis levels weaken the ability of N5P to inhibit inflammation.

SIGNIFICANCE

N5P may alleviate inflammation in ALI through the HIF-1α/glycolysis/ASIC1a signaling pathway. The present findings have provided pertinent information in the assessment of N5P as a potential, future therapeutic drug for ALI.

Jian-Ti-Kang-Yi decoction alleviates poly(I:C)-induced pneumonia by inhibiting inflammatory response, reducing oxidative stress, and modulating host metabolism

Jian-Ti-Kang-Yi decoction (JTKY) is widely used in the treatment of COVID-19. However, the protective mechanisms of JTKY against pneumonia remain unknown. In this study, polyinosinic-polycytidylic acid (poly(I:C)), a mimic of viral dsRNA, was used to induce pneumonia in mice; the therapeutic effects of JTKY on poly(I:C)-induced pneumonia model mice were evaluated. In addition, the anti-inflammatory and anti-oxidative potentials of JTKY were also investigated. Lastly, the metabolic regulatory effects of JTKY in poly(I:C)-induced pneumonia model mice were studied using untargeted metabolomics. Our results showed that JTKY treatment decreased the wet-to-dry ratio in the lung tissue, total protein concentration, and total cell count of the bronchoalveolar lavage fluid (BALF). Hematoxylin and Eosin (HE) and Masson staining indicated that the JTKY treatment alleviated the pathological changes and decreased the fibrotic contents in the lungs. JTKY treatment also decreased the expression of pro-inflammatory cytokines [interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha (TNF-α)] and increased the levels of immunomodulatory cytokines (IL-4 and IL-10) in the BALF and serum. Flow cytometry analysis showed that the JTKY treatment lowered the ratio of CD86+/CD206+ macrophages in the BALF, decreased inducible nitric oxide synthase (iNOS) level, and increased arginase 1 (Arg-1) level in lung. JTKY also lowered CD11b+Ly6G+ neutrophils in BALF and decreased myeloperoxidase (MPO) activity in lung. Moreover, it also elevated superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and decreased methane dicarboxylic aldehyde (MDA) level in lung. Untargeted metabolomic analysis showed that the JTKY treatment could affect 19 metabolites in lung, such as L-adrenaline, L-asparagine, ornithine, and alpha-ketoglutaric acid. These metabolites are associated with the synthesis and degradation of ketone bodies, butanoate, alanine, aspartate, and glutamate metabolism, and tricarboxylic acid (TCA) cycle processes. In conclusion, our study demonstrated that treatment with JTKY ameliorated poly(I:C)-induced pneumonia. The mechanism of action of JTKY may be associated with the inhibition of the inflammatory response, the reduction of oxidative stress, and the regulation of the synthesis and degradation of ketone bodies, TCA cycle, and metabolism of alanine, aspartate, glutamate, and butanoate processes in lung.

Integrated multi-omics reveals the activated retinal microglia with intracellular metabolic reprogramming contributes to inflammation in STZ-induced early diabetic retinopathy

Diabetic retinopathy (DR) is the leading cause of visual impairment and blindness among working-age people. Inflammation is recognized as a critical driver of the DR process. However, the main retina-specific cell type producing pro-inflammatory cytokines and its mechanism underlying DR are still unclear. Here, we used single-cell sequencing to identify microglia with metabolic pathway alterations that were the main source of IL-1β in STZ-induced DR mice. To profile the full extent of local metabolic shifts in activated microglia and to reveal the metabolic microenvironment contributing to immune mechanisms, we performed integrated metabolomics, lipidomics, and RNA profiling analyses in microglia cell line samples representative of the DR microenvironment. The results showed that activated microglia with IL-1β increase exhibited a metabolic bias favoring glycolysis, purine metabolism, and triacylglycerol synthesis, but less Tricarboxylic acid (TCA). In addition, some of these especially glycolysis was necessary to facilitate their pro-inflammation. These findings suggest that activated microglia with intracellular metabolic reprogramming in retina may contribute to pro-inflammation in the early DR.

Dietary Garlic Powder Alleviates Lipopolysaccharide-Induced Inflammatory Response and Oxidative Stress through Regulating the Immunity and Intestinal Barrier Function in Broilers

Simple Summary

This research was performed to determine the positive effects of GP on growth and intestinal function in lipopolysaccharide (LPS) challenged broilers. Results show that LPS challenge enhanced the weight loss rate, decreased the immunity and antioxidant capability, increased the intestinal permeability in broilers. When compared with LPS group, broilers fed with GP exhibited improved weight loss rate and jejunum villus height, enhanced ileum antioxidant function, and ameliorated intestinal barrier function. The LPS-challenged broilers in GP group had higher immunity than that of broilers in antibiotics group. In conclusion, GP supplementation could act as a natural alternative to antibiotic additive to alleviate the LPS-induced weight loss rate, inflammatory responses, and oxidative stress in broilers by improving the immunity and intestinal function.

Abstract

Garlic powder (GP) has the outstanding antibacterial, antifungal, antiviral, anti-parasitic and antioxidant characteristics because of its various contained bioactive components, such as alliin, allicin, and polysaccharide, etc. It has been widely used as a native medicine and shown to prevent a variety of diseases. This research was performed to determine the positive effects of GP on growth and intestinal function in lipopolysaccharide (LPS) challenged broilers. A total of 480 one-day-old male Ross 308 broilers of similar initial body weight were randomly divided into four groups with 8 replicates per treatment and 15 chicks each replicate. LPS challenge enhanced the weight loss rate, decreased the immunity and antioxidant capability, increased the intestinal permeability in broilers. When compared with LPS group, broilers fed with GP exhibited improved weight loss rate and jejunum villus height, enhanced ileum antioxidant function, and ameliorated intestinal barrier function. The LPS-challenged broilers in GP group had higher immunity than that of broilers in antibiotics group. GP supplementation could act as a natural alternative to antibiotic additive to alleviate the LPS-induced weight loss rate, inflammatory responses, and oxidative stress in broilers by improving the immunity and intestinal function.

The expression of Hexokinase 2 and its hub genes are correlated with the prognosis in glioma

BACKGROUND

Hexokinase 2 (HK2) is an enzyme that catalyses the conversion of glucose to glucose-6-phosphate, which has been found to be associated with malignant tumour growth. However, the potential immunological and clinical significance of HK2, especially in terms of prognostic prediction for patients with glioma, has not been fully elucidated.

METHODS

To investigate the expression, immunological and clinical significance of HK2 in patients with glioma, several databases, including ONCOMINE, TIMER2.0, GEPIA, CGGA, UCSC, LinkedOmics, Metascape, STRING, GSCA, and TISIDB, as well as biochemical, cellular, and pathological analyses, were used in this study. In addition, we performed univariate, multivariate Cox regression and nomogram analyses of the hub genes positively and negatively correlated with HK2 to explore the potential regulatory mechanism in the initiation and development of glioma.

RESULTS

Our results demonstrated that HK2 was highly expressed in most malignant cancers. HK2 expression was significantly higher in lower grade glioma (LGG) and glioblastoma (GBM) than in adjacent normal tissue. In addition, HK2 expression was significantly correlated with clinical parameters, histological manifestations, and prognosis in glioma patients. Specifically, the data from The Cancer Genome Atlas downloaded from UCSC Xena database analysis showed that high expression of HK2 was strongly associated with poor prognosis in glioma patients. The LinkedOmics database indicated that HK2-related genes were mainly enriched in immune-related cells. In LGG and GBM tissues, HK2 expression is usually correlated with recognized immune checkpoints and the abundance of multiple immune infiltrates. Similarly, the Metascape database revealed that HK2-related genes were mainly enriched and annotated in immune-related pathways and immune cells. Further investigations also confirmed that the inhibition of HK2 expression remarkably suppressed metastasis and vasculogenic mimicry (VM) formation in glioma cells through regulating the gene expression of inflammatory and immune modulators.

CONCLUSION

HK2 expression was closely associated with the malignant properties of glioma through activating multiple immune-related signalling pathways to regulate immune responses and the infiltration of immune cells. Thus, HK2 and its hub genes may be a potential target for the treatment of glioma.

Vasorin contributes to lung injury via FABP4-mediated inflammation

BACKGROUND

Lung injury caused by pulmonary inflammation is one of the main manifestations of respiratory diseases. Vasorin (VASN) is a cell-surface glycoprotein encoded by the VASN gene and is expressed in the lungs of developing mouse foetuses. Previous research has revealed that VASN is associated with many diseases. However, its exact function in the lungs and the underlying mechanism remain poorly understood.

METHODS AND RESULTS

To investigate the molecular mechanisms involved in lung disease caused by VASN deficiency, a VASN gene knockout (VASN^-/-) model was established. The pathological changes in the lungs of VASN^-/- mice were similar to those in a lung injury experimental mouse model. We further analysed the transcriptomes of the lungs of VASN^-/- mice and wild-type mice. Genes in twenty-four signalling pathways were enriched in the lungs of VASN^-/- mice, among which PPAR signalling pathway genes (3 genes, FABP4, Plin1, AdipoQ, were upregulated, while apoA5 was downregulated) were found to be closely related to lung injury. The most significantly changed lung injury-related gene, FABP4, was selected for further verification. The mRNA and protein levels of FABP4 were significantly increased in the lungs of VASN^-/- mice, as were the mRNA and protein levels of the inflammatory factors IL-6, TNF-α and IL-1β.

CONCLUSIONS

We believe that these data provide molecular evidence for the regulatory role of VASN in inflammation in the context of lung injury.

Fn14 exacerbates acute lung injury by activating the NLRP3 inflammasome in mice

BACKGROUND

Uncontrolled inflammation is an important factor in the occurrence and development of acute lung injury (ALI). Fibroblast growth factor-inducible 14 (Fn14), a plasma membrane-anchored receptor, takes part in the pathological process of a variety of acute and chronic inflammatory diseases. However, the role of Fn14 in ALI has not yet been elucidated. This study aimed to investigate whether the activation of Fn14 exacerbated lipopolysaccharide (LPS)-induced ALI in mice.

METHODS

In vivo, ALI was induced by intratracheal LPS-challenge combined with/without Fn14 receptor blocker aurintricarboxylic acid (ATA) treatment in C57BL/6J mice. Following LPS administration, the survival rate, lung tissue injury, inflammatory cell infiltration, inflammatory factor secretion, oxidative stress, and NLRP3 inflammasome activation were assessed. In vitro, primary murine macrophages were used to evaluate the underlying mechanism by which Fn14 activated the NLRP3 inflammasome. Lentivirus was used to silence Fn14 to observe its effect on the activation of NLRP3 inflammasome in macrophages.

RESULTS

In this study, we found that Fn14 expression was significantly increased in the lungs of LPS-induced ALI mice. The inhibition of Fn14 with ATA downregulated the protein expression of Fn14 in the lungs and improved the survival rate of mice receiving a lethal dose of LPS. ATA also attenuated lung tissue damage by decreasing the infiltration of macrophages and neutrophils, reducing inflammation, and suppressing oxidative stress. Importantly, we found that ATA strongly inhibited the activation of NLRP3 inflammasome in the lungs of ALI mice. Furthermore, in vitro, TWEAK, a natural ligand of Fn14, amplified the activation of NLRP3 inflammasome in the primary murine macrophage. By contrast, inhibition of Fn14 with shRNA decreased the expression of Fn14, NLRP3, Caspase-1 p10, and Caspase-1 p20, and the production of IL-1β and IL-18. Furthermore, the activation of Fn14 promoted the production of reactive oxygen species and inhibited the activation of Nrf2-HO-1 in activated macrophages.

CONCLUSIONS

Our study first reports that the activation of Fn14 aggravates ALI by amplifying the activation of NLRP3 inflammasome. Therefore, blocking Fn14 may be a potential way to treat ALI.

Progressive Host-Directed Strategies to Potentiate BCG Vaccination Against Tuberculosis

The pursuit to improve the TB control program comprising one approved vaccine, M. bovis Bacille Calmette-Guerin (BCG) has directed researchers to explore progressive approaches to halt the eternal TB pandemic. Mycobacterium tuberculosis (M.tb) was first identified as the causative agent of TB in 1882 by Dr. Robert Koch. However, TB has plagued living beings since ancient times and continues to endure as an eternal scourge ravaging even with existing chemoprophylaxis and preventive therapy. We have scientifically come a long way since then, but despite accessibility to the standard antimycobacterial antibiotics and prophylactic vaccine, almost one-fourth of humankind is infected latently with M.tb. Existing therapeutics fail to control TB, due to the upsurge of drug-resistant strains and increasing incidents of co-infections in immune-compromised individuals. Unresponsiveness to established antibiotics leaves patients with no therapeutic possibilities. Hence the search for an efficacious TB immunization strategy is a global health priority. Researchers are paving the course for efficient vaccination strategies with the radically advanced operation of core principles of protective immune responses against M.tb. In this review; we have reassessed the progression of the TB vaccination program comprising BCG immunization in children and potential stratagems to reinforce BCG-induced protection in adults.

The inhibition of GLUT1-induced glycolysis in macrophage by phloretin participates in the protection during acute lung injury

The increased level of glycolysis in macrophage aggravates lipopolysaccharide (LPS)-induced acute lung injury (ALI). Glucose transporter 1 (GLUT1) serves as a ubiquitously expressed glucose transporter, which could activate inflammatory response by mediating glycolysis. Phloretin (PHL), an apple polyphenol, is also an inhibitor of GLUT1, possessing potent anti-inflammatory effects in various diseases. However, the potential role of PHL in ALI remains unclear till now. This study aims to investigate the impacts of PHL on ALI as well as its possible mechanisms. A mouse ALI model was established via intratracheal injection of LPS. LPS-induced primary macrophages were used to mimic in vitro ALI. Mice were pretreated with low or high dosage of PHL for 7 days via intragastric administration once a day before LPS injection. The results showed that PHL pretreatment significantly prevented LPS-induced lung pathological injury and inflammatory response. Meantime, PHL pretreatment also decreased the level of glycolysis in macrophage during ALI. In terms of mechanism, PHL inhibited the mRNA and protein expression of GLUT1. In vitro experiments further showed GLUT1 overexpression in macrophage by infection with lentivirus could abolish the inhibition of inflammation and glycolysis mediated by PHL, suggesting that GLUT1 was essential for the protection of PHL. Taken together, PHL pretreatment may protect against LPS-induced ALI by inhibiting glycolysis in macrophage in a GLUT1-dependent manner, which may be a candidate against ALI in the future.

WIN55212-2 alleviates acute lung injury by inhibiting macrophage glycolysis through the miR-29b-3p/FOXO3/PFKFB3 axis

BACKGROUND

Acute lung injury (ALI) is a severe organ dysfunction caused by sepsis. WIN55212-2 (WIN) is a cannabinoid receptor agonist. Activation of cannabinoid type 2 receptor can alleviate septic lung injury. Therefore, the effects of WIN on sepsis-related ALI were evaluated.

METHODS

MiR-29b-3p, FOXO3 and PFKFB3 levels, as well as M1 and M2 macrophage markers were assessed by RT-qPCR in MH-S cells after lipopolysaccharide (LPS) and WIN treatment. ChIP and dual luciferase reporter assays determined molecules interactions. Glycolysis-related proteins were evaluated by Western blotting assay. Lactic acid and ATP were also tested. Furthermore, the effect of WIN was tested in sepsis mice model. HE staining evaluated the histopathological changes in mouse lung tissues. The number of inflammatory cells and macrophages, protein concentration and lactic acid content were detected in mouse bronchoalveolar lavage fluid.

RESULTS

We found that WIN suppressed M1 polarization and glycolysis in alveolar macrophages induced by LPS. Moreover, WIN inhibited FOXO3 by up-regulating miR-29b-3p. Furthermore, we verified that FOXO3 induced macrophage M1 polarization and glycolysis through activating PFKFB3. In vivo, WIN alleviated ALI in mice with sepsis.

CONCLUSION

Our results reveal that WIN inhibits macrophage glycolysis through the miR-29b-3p/ FOXO3/PFKFB3 axis, suggesting new therapeutic targets to alleviate sepsis-related ALI.

Knockdown of PFKFB2 Alleviates Oxidative Stress and Inflammation in LPS-Induced Alveolar Epithelial Cells by Reducing Glycolysis

Glycolysis is the most important mode of energy metabolism in endothelial cells and has been shown to be involved in the pathological processes of acute and chronic inflammatory diseases. Phosphofructokinase 2/fructose-2, 6-bisphosphatase 2 (PFKFB2) exerts an important regulatory factor in the process of glycolysis by catalyzing the synthesis and degradation of fructose 2,6-bisphosphate. There is still unclear however, whether PFKFB2 can play a role in sepsis-related acute lung injury by regulating glycolysis. This research examines the role and mechanism of PFKFB2 in LPS-induced alveolar epithelial cells. In this study, the detection of mRNA expressions of PFKFB2, glycolysis and inflammation-related proteins employed quantitative real-time PCR (RTqPCR). Western blot was applied to examine the expressions of all proteins. The viability of A549 cells was assessed with the use of cell counting kit (CCK)-8. The expressions of related factors were quantified by commercial assay kits, respectively. The experimental results showed that the expression of PFKFB2 was increased in sepsis. Knockdown of PFKFB2 alleviated glycolysis in LPS-induced A549 cells. Additionally, knockdown of PFKFB2 reduced LPS-induced oxidative stress and inflammation through glycolysis. Knockdown of PFKFB2 also mitigated LPS-induced oxidative stress and inflammation in alveolar epithelial cells by reducing glycolysis. Hence, PFKFB2 may be served as an effective target for the treatment of sepsis-related acute lung injury.

Reprogramming Macrophage Metabolism and its Effect on NLRP3 Inflammasome Activation in Sepsis

Sepsis, the most common life-threatening multi-organ dysfunction syndrome secondary to infection, lacks specific therapeutic strategy due to the limited understanding of underlying mechanisms. It is currently believed that inflammasomes play critical roles in the development of sepsis, among which NLRP3 inflammasome is involved to most extent. Recent studies have revealed that dramatic reprogramming of macrophage metabolism is commonly occurred in sepsis, and this dysregulation is closely related with the activation of NLRP3 inflammasome. In view of the fact that increasing evidence demonstrates the mechanism of metabolism reprogramming regulating NLRP3 activation in macrophages, the key enzymes and metabolites participated in this regulation should be clearer for better interpreting the relationship of NLRP3 inflammasome and sepsis. In this review, we thus summarized the detail mechanism of the metabolic reprogramming process and its important role in the NLRP3 inflammasome activation of macrophages in sepsis. This mechanism summarization will reveal the applicational potential of metabolic regulatory molecules in the treatment of sepsis.

NF-κB and AMPK-Nrf2 pathways support the protective effect of polysaccharides from Polygonatum cyrtonema Hua in lipopolysaccharide-induced acute lung injury

ETHNOPHARMACOLOGICAL RELEVANCE

The raw and honey-processed P. cyrtonema recorded in ancient classics of Chinese medicine as having the effect of moisturizing the lungs and relieving coughs, and it has also been proved to have therapeutic effects on lung diseases in modern research. Polysaccharides are the main components with biological activities in raw and honey-processed P. cyrtonema, but there is no research for their lung-protective effect.

AIM OF STUDY

This study aimed to investigate the protective effect and the possible mechanism of polysaccharides from raw and honey-processed P. cyrtonema in LPS-induced acute lung injury in mice.

MATERIALS AND METHODS

Polysaccharides, PCP and HPCP, were respectively separated and extracted from raw and honey-processed P. cyrtonema, and the molecular weight, monosaccharide composition and other basic chemical characteristics were analyzed by HPGCP, HPLC, FI-IR, and NMR. The model of ALI mice was established by intratracheal instillation of LPS. Moreover, the protective effects of PCP and HPCP for ALI mice were evaluated by detecting the wet-to-dry ratio and histopathology in the lungs, the content of inflammatory factors TNF-α, IL-6, IL-1β in BLAF, and the content of MPO and SOD in lung tissue. In addition, the lung-protective mechanism of PCP and HPCP was explored by detecting the levels of some proteins and mRNA related to inflammation and oxidative stress pathways.

RESULTS

PCP and HPCP with molecular weights of 8.842 × 10³ and 5.521 × 10³Da were mainly composed of three monosaccharides. Moreover, it is found that fructose and galactose were mainly β-D, and glucose was α-D. Both PCP and HPCP could significantly improve lung injury, reduce the level of inflammatory factors in BALF and the level of MPO in lung tissue, and increase the level of SOD. In addition, PCR and WB indicated that PCP and HPCP at least inhibited pulmonary inflammation through the NF-κB pathway, and reduced the occurrence of pulmonary oxidative stress through the AMPK-Nrf2 pathway.

CONCLUSIONS

Polysaccharides from raw and honey-processed P. cyrtonema had a protective effect in LPS-induced lung injury in mice. This effect may be related to the antioxidant and anti-inflammatory activities of PCP and HPCP in the lungs through the NF-κB pathway and AMPK-Nrf2 pathway. And HPCP seems to perform more than PCP.

Qingfei Litan Decoction Against Acute Lung Injury/Acute Respiratory Distress Syndrome: The Potential Roles of Anti-Inflammatory and Anti-Oxidative Effects

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is an acute respiratory failure syndrome characterized by progressive arterial hypoxemia and dyspnea. Qingfei Litan (QFLT) decoction, as a classic prescription for the treatment of acute respiratory infections, is effective for the treatment of ALI/ARDS. In this study, the compounds, hub targets, and major pathways of QFLT in ALI/ARDS treatment were analyzed using Ultra high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS) and systemic pharmacology strategies. UHPLC-MS identified 47 main components of QFLT. To explore its anti-inflammatory and anti-oxidative mechanisms, gene ontology (Go) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment and network pharmacological analysis were conducted based on the main 47 components. KEGG enrichment analysis showed that TNF signaling pathway and Toll-like receptor signaling pathway may be the key pathways of ALI/ARDS. We explored the anti-inflammatory and anti-oxidative pharmacological effects of QFLT in treatment of ALI/ARDS in vivo and in vitro. QFLT suppressed the levels of proinflammatory cytokines and alleviated oxidative stress in LPS-challenged mice. In vitro, QFLT decreased the levels of TNF-α, IL-6, IL-1β secreted by LPS-activated macrophages, increased GSH level and decreased the LPS-activated reactive oxygen species (ROS) in lung epithelial A549 cells. This study suggested that QFLT may have anti-inflammatory and anti-oxidative effects on ALI/ARDS, combining in vivo and in vitro experiments with systemic pharmacology, providing a potential therapeutic strategy option.

Beneficial effects of aloperine on inflammation and oxidative stress by suppressing necroptosis in lipopolysaccharide-induced acute lung injury mouse model

RATIONALE

Alveolar epithelial cell death, inflammation, and oxidative stress are typical features of acute lung injury (ALI). Aloperine (Alo), an alkaloid isolated from Sophora alopecuroides, has been reported to display various biological effects, such as anti-inflammatory, immunoregulatory, and anti-oxidant properties. In this study, we investigated the effects and mechanisms of Alo in treating a lipopolysaccharide (LPS)-induced ALI in a murine model.

METHODS

The effects of Alo in LPS-induced ALI were investigated in C57BL/6 mice. The RIPK1 inhibitor (Nec-1) and the RIPK3 inhibitor (GSK'872) were used to evaluate the relationship of necroptosis, NF-κB activation, and PDC subunits in LPS-treated mouse alveolar epithelial cells (MLE-12). Then the effects of Alo on necroptosis, inflammation, and oxidative stress of LPS-stimulated MLE-12 cells were evaluated.

RESULTS

Alo significantly attenuated histopathological lung injuries and reduced lung wet/dry ratio in LPS-induced ALI mice. Alo also remarkedly reduced total protein and neutrophils recruitment in bronchoalveolar lavage fluid of ALI mice. Meanwhile, Alo ameliorated the LPS-induced necroptosis in the lungs of ALI mice. The RIPK3 inhibitor GSK'872, but not the RIPK1 inhibitor Nec-1, reversed LPS-induced p65 phosphorylation and translocation to the nucleus in MLE-12 cells. GSK'872 also reversed the LPS-induced increase in ROS and binding of RIPK3 and PDC subunits in MLE-12 cells. Moreover, Alo down-regulated the levels of p-RIPK1, p-RIPK3, p-MLKL, p-p65, the translocation of p65 to the nucleus, and reduced the expression of IL-6 and IL-8 in LPS-stimulated MLE-12 cells. Alo also inhibited the binding of RIPK3 and PDC-E1α, PDC-E1β, PDC-E2, and PDC-E3 and the ROS production in LPS-treated MLE-12 cells.

CONCLUSION

The present study validated the beneficial effects of Alo on LPS-induced ALI , suggesting Alo may be a new drug candidate against ALI.

Podocyte specific deletion of PKM2 ameliorates LPS-induced podocyte injury through beta-catenin

BACKGROUND

Acute kidney injury (AKI) is associated with a severe decline in kidney function caused by abnormalities within the podocytes' glomerular matrix. Recently, AKI has been linked to alterations in glycolysis and the activity of glycolytic enzymes, including pyruvate kinase M2 (PKM2). However, the contribution of this enzyme to AKI remains largely unexplored.

METHODS

Cre-loxP technology was used to examine the effects of PKM2 specific deletion in podocytes on the activation status of key signaling pathways involved in the pathophysiology of AKI by lipopolysaccharides (LPS). In addition, we used lentiviral shRNA to generate murine podocytes deficient in PKM2 and investigated the molecular mechanisms mediating PKM2 actions in vitro.

RESULTS

Specific PKM2 deletion in podocytes ameliorated LPS-induced protein excretion and alleviated LPS-induced alterations in blood urea nitrogen and serum albumin levels. In addition, PKM2 deletion in podocytes alleviated LPS-induced structural and morphological alterations to the tubules and to the brush borders. At the molecular level, PKM2 deficiency in podocytes suppressed LPS-induced inflammation and apoptosis. In vitro, PKM2 knockdown in murine podocytes diminished LPS-induced apoptosis. These effects were concomitant with a reduction in LPS-induced activation of β-catenin and the loss of Wilms' Tumor 1 (WT1) and nephrin. Notably, the overexpression of a constitutively active mutant of β-catenin abolished the protective effect of PKM2 knockdown. Conversely, PKM2 knockdown cells reconstituted with the phosphotyrosine binding-deficient PKM2 mutant (K433E) recapitulated the effect of PKM2 depletion on LPS-induced apoptosis, β-catenin activation, and reduction in WT1 expression.

CONCLUSIONS

Taken together, our data demonstrates that PKM2 plays a key role in podocyte injury and suggests that targetting PKM2 in podocytes could serve as a promising therapeutic strategy for AKI.

TRIAL REGISTRATION

Not applicable. Video abstract.

Metabolic Reprogramming of Innate Immune Cells as a Possible Source of New Therapeutic Approaches in Autoimmunity

Immune cells undergo different metabolic pathways or immunometabolisms to interact with various antigens. Immunometabolism links immunological and metabolic processes and is critical for innate and adaptive immunity. Although metabolic reprogramming is necessary for cell differentiation and proliferation, it may mediate the imbalance of immune homeostasis, leading to the pathogenesis and development of some diseases, such as autoimmune diseases. Here, we discuss the effects of metabolic changes in autoimmune diseases, exerted by the leading actors of innate immunity, and their role in autoimmunity pathogenesis, suggesting many immunotherapeutic approaches.

L-OPA1 deficiency aggravates necroptosis of alveolar epithelial cells through impairing mitochondrial function during ALI in mice

Necroptosis, a recently described form of programmed cell death, is the main way of alveolar epithelial cells (AECs) death in acute lung injury (ALI). While the mechanism of how to trigger necroptosis in AECs during ALI has been rarely evaluated. Long optic atrophy protein 1 (L-OPA1) is a crucial mitochondrial inner membrane fusion protein, and its deficiency impairs mitochondrial function. This study aimed to investigate the role of L-OPA1 deficiency-mediated mitochondrial dysfunction in AECs necroptosis. We comprehensively investigated the detailed contribution and molecular mechanism of L-OPA1 deficiency in AECs necroptosis by inhibiting or activating L-OPA1. Firstly, our data showed that L-OPA1 expression was down-regulated in the lungs and AECs under the lipopolysaccharide (LPS) challenge. Furthermore, inhibition of L-OPA1 aggravated the pathological injury, inflammatory response, and necroptosis in the lungs of LPS-induced ALI mice. In vitro, inhibition of L-OPA1 induced necroptosis of AECs, while activation of L-OPA1 alleviated necroptosis of AECs under the LPS challenge. Mechanistically, inhibition of L-OPA1 aggravated necroptosis of AECs by inducing mitochondrial fragmentation and reducing mitochondrial membrane potential. While activation of L-OPA1 had the opposite effects. In summary, these findings indicate for the first time that L-OPA1 deficiency mediates mitochondrial fragmentation, induces necroptosis of AECs, and exacerbates ALI in mice. This article is protected by copyright. All rights reserved.

COX-2/sEH Dual Inhibitor PTUPB Attenuates Epithelial-Mesenchymal Transformation of Alveolar Epithelial Cells via Nrf2-Mediated Inhibition of TGF-β1/Smad Signaling

Background

Arachidonic acid (ARA) metabolites are involved in the pathogenesis of epithelial-mesenchymal transformation (EMT). However, the role of ARA metabolism in the progression of EMT during pulmonary fibrosis (PF) has not been fully elucidated. The purpose of this study was to investigate the role of cytochrome P450 oxidase (CYP)/soluble epoxide hydrolase (sEH) and cyclooxygenase-2 (COX-2) metabolic disorders of ARA in EMT during PF.

Methods

A signal intratracheal injection of bleomycin (BLM) was given to induce PF in C57BL/6 J mice. A COX-2/sEH dual inhibitor PTUPB was used to establish the function of CYPs/COX-2 dysregulation to EMT in PF mice. In vitro experiments, murine alveolar epithelial cells (MLE12) and human alveolar epithelial cells (A549) were used to explore the roles and mechanisms of PTUPB on transforming growth factor (TGF)-β1-induced EMT.

Results

PTUPB treatment reversed the increase of mesenchymal marker molecule α-smooth muscle actin (α-SMA) and the loss of epithelial marker molecule E-cadherin in lung tissue of PF mice. In vitro, COX-2 and sEH protein levels were increased in TGF-β1-treated alveolar epithelial cells (AECs). PTUPB decreased the expression of α-SMA and restored the expression of E-cadherin in TGF-β1-treated AECs, accompanied by reduced migration and collagen synthesis. Moreover, PTUPB attenuated TGF-β1-Smad2/3 pathway activation in AECs via Nrf2 antioxidant cascade.

Conclusion

PTUPB inhibits EMT in AECs via Nrf2-mediated inhibition of the TGF-β1-Smad2/3 pathway, which holds great promise for the clinical treatment of PF.

Meldonium Ameliorates Hypoxia-Induced Lung Injury and Oxidative Stress by Regulating Platelet-Type Phosphofructokinase-Mediated Glycolysis

Hypoxic environments at high altitudes influence the long-term non-altitude health of residents, by inducing changes in metabolism and the mitochondria, severe lung injury, and endangering life. This study was aimed to determine whether meldonium can ameliorate hypoxia-induced lung injury and investigate its possible molecular mechanisms. We used Swiss mice and exposed type Ⅱ alveolar epithelial cell to hypobaric hypoxic conditions to induce lung injury and found that meldonium has significant preventive effect, which was associated with the regulation of glycolysis. We found using human proteome microarrays assay, molecular docking, immunofluorescence and pull-down assay that the target protein of meldonium is a platelet-type phosphofructokinase (PFKP), which is a rate-limiting enzyme of glycolysis. Also, meldonium promotes the transfer of nuclear factor erythroid 2-related factor 2 (Nrf2) from the cytoplasm to the nucleus, which mitigates oxidative stress and mitochondrial damage under hypoxic condition. Mechanistically, meldonium ameliorates lung injury by targeting PFKP to regulate glycolysis, which promotes Nrf2 translocation from the cytoplasm to the nucleus to alleviate oxidative stress and mitochondrial damage under hypoxic condition. Our study provides a novel potential prevention and treatment strategy against hypoxia-induced lung injury.

NORAD modulates miR-30c-5p-LDHA to protect lung endothelial cells damage

Acute lung injury (ALI) is a devastating human malignancy characterized by excessively uncontrolled inflammation and lung endothelial dysfunction. Non-coding RNAs play essential roles in endothelial protections during the pathological processes of ALI. The precise functions and molecular mechanisms of the lncRNA-NORAD-mediated endothelial protection remain obscure. This study reports NORAD was significantly induced in human pulmonary microvascular endothelial cells (HPMECs) under lipopolysaccharide (LPS) treatment. Silencing NORAD effectively protected HPMECs against the LPS-induced cell dysfunction. In addition, RNA pull-down and luciferase assay validated that NORAD sponged miR-30c-5p, which showed reverse functions of NORAD in the LPS-induced cell injury of HPMECs. Furthermore, the glucose metabolism of HPMECs was significantly elevated under LPS stimulation which promoted the glucose consumption and extracellular acidification rate (ECAR) of HPMECs. Inhibiting NORAD or overexpressing miR-30c-5p suppressed glucose metabolism in HPMECs, leading to protective effects on HPMECs under LPS stimulation. The glycolysis key enzyme, lactate dehydrogenase-A (LDHA), was subsequently identified as a direct target of miR-30c-5p. Finally, recovery of miR-30c-5p in NORAD-overexpressing HPMECs effectively overrode the NORAD-promoted glycolysis and impaired endothelial dysfunction under LPS stimulation by targeting LDHA. Summarily, we demonstrated a NORAD-miR-30c-5p-LDHA-glycolysis axis in the LPS-induced HPMECs dysfunction in vitro and in vivo, contributing to the development of anti-ALI therapeutic approaches.

Interactions between NLRP3 inflammasome and glycolysis in macrophages: New insights into chronic inflammation pathogenesis

NLRP3 inflammasome activation in macrophages fuels sterile inflammation, which has been tied with metabolic reprogramming characterized by high glycolysis and low oxidative phosphorylation. The key enzymes in glycolysis and glycolysis‐related products can regulate and activate NLRP3 inflammasome. In turn, NLRP3 inflammasome is considered to affect glycolysis, as well. However, the exact mechanism remains ambiguous. On the basis of these findings, the focus of this review is mainly on the developments in our understanding of interaction between NLRP3 inflammasome activation and glycolysis in macrophages, and small molecule compounds that influence the activation of NLRP3 inflammasomes by regulating glycolysis in macrophages. The application of this interaction in the treatment of diseases is also discussed. This paper may yield valuable clues for development of novel therapeutic agent for NLRP3 inflammasome‐related diseases.

Multi-Omics Revealed the Protective Effects of Rhamnolipids in Lipopolysaccharide Challenged Broilers

Rhamnolipid (RL) is a glycolipid biosurfactant and exhibits the following outstanding characteristics: strong antibacterial properties, low toxicity, and high biodegradability. The present research was conducted to explore the protective effects and mechanisms of rhamnolipids as an alternative to antibiotics in LPS (lipopolysaccharide)-challenged broilers. 16S rRNA gene sequencing and metabolomics were used for analyzing the cecal microbial composition and serum metabolites. Dietary antibiotics and RLS supplementation decreased the weight loss rate, enhanced serum immunoglobulin levels, reduced serum diamine oxidase and D-lactate acid concentration, and improved the symptoms of intestinal bleeding and villus height, when broilers were challenged with LPS. The addition of RLS in the diet enhanced serum interleukin-4 and interleukin-10 contents and reduced serum interleukin-6 and tumor necrosis factor-α levels in LPS-challenged broilers compared with the antibiotics group. Spearman’s correlation analysis revealed that RLS may alleviate LPS-induced inflammatory responses through altering the 6-methoxymellein level in broilers. The genus Bacteroides may contribute to the decreased weight loss rate via regulating the serum lysoPC [20:5(5Z,8Z,11Z,14Z,17Z)] secretion. RLS alleviates LPS-induced intestinal injury, enhances the growth and immunity, ameliorates intestinal microflora, and improves serum metabolites in LPS-challenged broilers. RLS exhibited better protective effect than antibiotic supplementation in the diet of LPS-challenged broilers. These findings provide potential regulation strategies and novel insights for RLS enhancing its protective effect in LPS-challenged broilers.

Mesenchymal Stem Cell-Derived Exosome Therapy of Microbial Diseases: From Bench to Bed

Microbial diseases are a global health threat, leading to tremendous casualties and economic losses. The strategy to treat microbial diseases falls into two broad categories: pathogen-directed therapy (PDT) and host-directed therapy (HDT). As the typical PDT, antibiotics or antiviral drugs directly attack bacteria or viruses through discerning specific molecules. However, drug abuse could result in antimicrobial resistance and increase infectious disease morbidity. Recently, the exosome therapy, as a HDT, has attracted extensive attentions for its potential in limiting infectious complications and targeted drug delivery. Mesenchymal stem cell-derived exosomes (MSC-Exos) are the most broadly investigated. In this review, we mainly focus on the development and recent advances of the application of MSC-Exos on microbial diseases. The review starts with the difficulties and current strategies in antimicrobial treatments, followed by a comprehensive overview of exosomes in aspect of isolation, identification, contents, and applications. Then, the underlying mechanisms of the MSC-Exo therapy in microbial diseases are discussed in depth, mainly including immunomodulation, repression of excessive inflammation, and promotion of tissue regeneration. In addition, we highlight the latest progress in the clinical translation of the MSC-Exo therapy, by summarizing related clinical trials, routes of administration, and exosome modifications. This review will provide fundamental insights and future perspectives on MSC-Exo therapy in microbial diseases from bench to bedside.

The glycolysis inhibitor 2-deoxyglucose ameliorates adjuvant-induced arthritis by regulating macrophage polarization in an AMPK-dependent manner

Macrophages are highly plastic cells critical for the development of rheumatoid arthritis (RA). Macrophages exhibit a high degree of pro-inflammatory plasticity in RA, accompanied by a metabolic reprogramming from oxidative phosphorylation (OXPHOS) to glycolysis. 2-deoxyglucose (2-DG), a glycolysis inhibitor, has previously been shown to exhibit anti-inflammatory and anti-arthritic properties. However, the specific mechanisms of inflammatory modulation by 2-DG remain unclear. This study used 2-DG to treat rats with adjuvant arthritis (AA) and investigated its specific anti-arthritic mechanisms in the murine-derived macrophage cell line RAW264.7 in vitro. 2-DG reduced the arthritis index as well as alleviated cellular infiltration, synovial hyperplasia, and bone erosion in AA rats. Moreover, 2-DG treatment modulated peritoneal macrophage polarization, increasing levels of the arginase1 (Arg1) and decreasing expression of the inducible nitric oxide synthase (iNOS). 2-DG activated AMP-activated protein kinase (AMPK) via phosphorylation and reduced activation of the nuclear factor κB (NF-κB) in peritoneal macrophages of AA rats. In vitro, we verified that 2-DG promoted macrophage transition from M1 to M2-type by upregulating the expression of p-AMPKα and suppressing NF-κB activation in LPS-stimulated RAW264.7 cells. LPS-induced macrophages exhibited a metabolic shift from glycolysis to OXPHOS following 2-DG treatment, as observed by reduced extracellular acidification rate (ECAR), lactate export, glucose consumption, as well as an elevated oxygen consumption rate (OCR) and intracellular ATP concentration. Importantly, changes in polarization and metabolism in response to 2-DG were dampened after AMPKα knockdown. These findings indicate that the anti-arthritic 2-DG effect is mediated by a modulation of macrophage polarization in an AMPK-dependent manner.

Extracellular citrate serves as a DAMP to activate macrophages and promote LPS-induced lung injury in mice

Citrate has a prominent role as a substrate in cellular energy metabolism. Recently, citrate has been shown to drive inflammation. However, the role of citrate in lipopolysaccharide (LPS)-induced acute lung injury (ALI) remains unclear. Here, we aimed to clarify whether extracellular citrate aggravated the LPS-induced ALI and the potential mechanism. Our findings demonstrated that extracellular citrate aggravated the pathological lung injury induced by LPS in mice, characterized by up-regulation of pro-inflammatory factors and over-activation of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome in the lungs. In vitro, we found that citrate treatment significantly augmented the expression of NLRP3 and pro-IL-1β and enhanced the translocation of NF-κB/p65 into the nucleus. Furthermore, extracellular citrate plus adenosine-triphosphate (ATP) significantly increased the production of reactive oxygen species (ROS) in primary murine macrophages. Inhibiting the production of ROS with a ROS scavenger N-acetyl-L-cysteine (NAC) attenuated the activation of NLRP3 inflammasome. Altogether, we conclude that extracellular citrate may serve as a damage-associated molecular pattern (DAMP) and aggravates LPS-induced ALI by activating the NLRP3 inflammasome.

Syringaresinol Resisted Sepsis-Induced Acute Lung Injury by Suppressing Pyroptosis Via the Oestrogen Receptor-β Signalling Pathway

Acute lung injury (ALI) is a common lung disease characterized by severe acute inflammatory lung injury in patients with sepsis. Syringaresinol (SYR) has been reported to have anti-apoptotic and anti-inflammatory effects, but whether it could prevent pyroptosis to improve sepsis-induced ALI remains unclear. The purpose of this work was to examine the impact of SYR on sepsis-induced ALI and investigate the underlying mechanisms. The ALI model was induced by caecal ligation and puncture (CLP) in C57BL/6 mice, structural damage in the lung tissues was determined using haematoxylin and eosin (HE) staining, and the levels of related inflammatory cytokines and macrophage polarization were examined by enzyme-linked immunosorbent assays (ELISAs) and flow cytometry, respectively. The activation of the NLRP3 inflammasome and the protein levels of TLR4, NF-κB and MAPKs was measured by western blotting. The results demonstrated that SYR pretreatment significantly reduced lung tissue histological damage, inhibited the production of proinflammatory cytokines and albumin in bronchoalveolar lavage fluid (BALF), and decreased myeloperoxidase (MPO) levels, thereby alleviating lung tissue injury. Meanwhile, septic mice treated with SYR displayed a higher survival rate and lower percentage of M1 macrophages in the BALF and spleen than septic mice. In addition, lung tissues from the CLP + SYR group exhibited downregulated protein expression of NLRP3, ASC, GSDMD caspase-1 p20 and TLR4, along with decreased phosphorylated levels of NF-κB, ERK, JNK and P38, indicating that SYR administration effectively prevented CLP-induced pyroptosis in the lung. SYR also suppressed LPS-induced pyroptosis in RAW 264.7 cells by inhibiting the activation of the NLRP3 inflammasome, which was abolished by an oestrogen receptor-β (ERβ) antagonist (PHTPP). In conclusion, SYR exerted protective effects on CLP-induced ALI via the oestrogen receptor-β signalling pathway.

Airway epithelial integrin β4-deficiency exacerbates lipopolysaccharide-induced acute lung injury

Airway epithelial cells, the first barrier of the respiratory tract, play an indispensable role in innate immunity. Integrin β4 (ITGB4) is a structural adhesion molecule that is involved in the pathological progression of acute inflammatory diseases and is downregulated in asthmatic patients. Research has shown that endothelial ITGB4 has proinflammatory properties in acute lung injury (ALI). However, the role of epithelial ITGB4 in a murine ALI model is still unknown. This study investigated the role of ITGB4 in lipopolysaccharide (LPS)-induced ALI. We found that ITGB4 in the airway epithelium had remarkably increased after the introduction of LPS in vivo and in vitro. Then, we constructed airway epithelial cell-specific ITGB4 knockout (ITGB4-/- ) mice to study its role in ALI. At a time point of 12 h after the tracheal injection of LPS, ITGB4-/- mice showed increased macrophages (mainly M1-type macrophages) and neutrophil infiltration into the lungs; inflammation-related proteins including interleukin (IL)-6, tumor necrosis factor, and IL-17A were significantly elevated compared to their levels in ITGB4+/+ mice. Furthermore, we investigated the role of ITGB4 in the anti-inflammatory response. Intriguingly, in the ITGB4-/-  + LPS group, we found significantly reduced expression of anti-inflammatory factors, including IL-10 messenger RNA (mRNA) and ARG-1 mRNA. We also observed that monocyte chemotactic protein (MCP-1) increased significantly both in vivo and in vitro. Airway epithelium activates macrophages, most likely driven by MCP-1, which we confirmed in the coculture of epithelia and macrophages. These phenomena indicate that ITGB4 in airway epithelial cells plays an important role in the process of inflammation and activation of macrophages in ALI. Overall, these data demonstrated a novel link between airway epithelial ITGB4 and the inflammatory response in LPS-induced ALI.

Paraquat promotes acute lung injury in rats by regulating alveolar macrophage polarization through glycolysis

The present study investigates whether paraquat (PQ) regulates polarization of alveolar macrophages through glycolysis and promotes the occurrence of acute lung injury in rats. In vivo, the PQ intraperitoneal injection was used to construct a model of acute lung injury in rats. In vitro, the study measured the effect of different concentrations of PQ on the viability of the alveolar macrophages, and explored the polarization and glycolysis metabolism of alveolar macrophages at different time points after PQ intervention. Compared with the normal control (NC) group, the lung pathological damage in rats increased gradually after PQ poisoning, reaching a significant degree at 48 h after poisoning. The PQ-poisoned rat serum showed increased expressions of interleukin-6 (IL-6), tumor necrosis factor- α (TNF-α), and M1 macrophage marker, iNOS, while the expression of interleukin-10 (IL-10) and M2 macrophage marker, Arg1, decreased. The toxic effect of PQ on alveolar macrophages was dose- and time-dependent. Compared with the NC group, IL-6 and TNF-α in the cell supernatant gradually increased after PQ intervention, while the IL-10 content gradually decreased. The PQ intervention in alveolar macrophages increased the expression of intracellular glycolysis rate-limiting enzyme pyruvate kinase isozymes M1/M2 (PKM1/M2), lactate, lactate/pyruvate ratio, and the polarization of alveolar macrophage towards M1. Inhibition of cellular glycolysis significantly reduced the PQ-induced alveolar macrophage polarization to M1 type. Thus, PQ induced increased polarization of lung macrophages toward M1 and decreased polarization toward M2, promoting acute lung injury. Therefore, it can be concluded that PQ regulates the polarization of alveolar macrophages through glycolysis.

UPLC-MS based plasma metabolomics and lipidomics reveal alterations associated with IgG4-related disease

OBJECTIVE

The pathogenesis of IgG4-related disease (IgG4-RD) remains unclear. Metabolomic profiling of IgG4-RD patients offers an opportunity to identify novel pathophysiological targets and biomarkers. This study aims to identify potential plasma biomarkers associated with IgG4-RD.

METHODS

Thirty newly diagnosed IgG4-RD patients, age-matched healthy controls and post-treated IgG4-RD patients were enrolled. Patients' clinical data, laboratory parameters and plasma were collected. Plasma was measured for ultraperformance liquid chromatography-tandem mass spectrometry based metabolomics and lipidomics profiling. Multivariate and univariate statistical analyses were conducted to identify potential biomarkers. The receiver operating characteristic and the correlations between biomarkers and clinical parameters were investigated.

RESULTS

The plasma metabolites are altered among healthy controls, newly diagnosed IgG4-RD and post-treated IgG4-RD groups. Of the identified features, eight metabolites were significantly perturbed in the IgG4-RD group, including glyceric acid 1,3-biphosphate (1,3-BPG), uridine triphosphate (UTP), uridine diphosphate glucose (UDP-Glc) or uridine diphosphate galactose (UDP-Gal), lysophospholipids, linoleic acid derivatives and ceramides. Receiver operating characteristic analysis indicated that UTP, UDP-Glc/UDP-Gal and LysoPC (18:1) had high sensitivity and specificity in diagnosis of IgG4-RD. A Pearson correlation analysis showed that 1,3-BPG and UTP were strongly correlated with clinical parameters.

CONCLUSION

IgG4-RD patients have a unique plasma metabolomic profile compared with healthy controls. Our study suggested that metabolomic profiling may provide important insights into pathophysiology and testable biomarkers for diagnosis of IgG4-RD.

Prolonged exposure to traffic-related particulate matter and gaseous pollutants implicate distinct molecular mechanisms of lung injury in rats

BACKGROUND

Exposure to air pollution exerts direct effects on respiratory organs; however, molecular alterations underlying air pollution-induced pulmonary injury remain unclear. In this study, we investigated the effect of air pollution on the lung tissues of Sprague-Dawley rats with whole-body exposure to traffic-related PM1 (particulate matter < 1 μm in aerodynamic diameter) pollutants and compared it with that in rats exposed to high-efficiency particulate air-filtered gaseous pollutants and clean air controls for 3 and 6 months. Lung function and histological examinations were performed along with quantitative proteomics analysis and functional validation.

RESULTS

Rats in the 6-month PM1-exposed group exhibited a significant decline in lung function, as determined by decreased FEF25-75% and FEV20/FVC; however, histological analysis revealed earlier lung damage, as evidenced by increased congestion and macrophage infiltration in 3-month PM1-exposed rat lungs. The lung tissue proteomics analysis identified 2673 proteins that highlighted the differential dysregulation of proteins involved in oxidative stress, cellular metabolism, calcium signalling, inflammatory responses, and actin dynamics under exposures to PM1 and gaseous pollutants. The presence of PM1 specifically enhanced oxidative stress and inflammatory reactions under subchronic exposure to traffic-related PM1 and suppressed glucose metabolism and actin cytoskeleton signalling. These factors might lead to repair failure and thus to lung function decline after chronic exposure to traffic-related PM1. A detailed pathogenic mechanism was proposed to depict temporal and dynamic molecular regulations associated with PM1- and gaseous pollutants-induced lung injury.

CONCLUSION

This study explored several potential molecular features associated with early lung damage in response to traffic-related air pollution, which might be used to screen individuals more susceptible to air pollution.

Metformin prevents PFKFB3-related aerobic glycolysis from enhancing collagen synthesis in lung fibroblasts by regulating AMPK/mTOR pathway

Aerobic glycolysis has been shown to contribute to the abnormal activation of lung fibroblasts with excessive collagen deposition in lipopolysaccharide (LPS)-induced pulmonary fibrosis. Targeting aerobic glycolysis in lung fibroblasts might therefore be considered as a promising therapeutic approach for LPS-induced pulmonary fibrosis. In the present study, the aim was to investigate whether metformin, a widely used agent for treating type 2 diabetes, could alleviate LPS-induced lung fibroblast collagen synthesis and its potential underlying mechanisms. Different concentrations of metformin were used to treat the human lung fibroblast MRC-5 cells after LPS challenge. Indicators of aerobic glycolysis in MRC-5 cells were detected by measuring glucose consumption and lactate levels in culture medium in addition to lactate dehydrogenase activity in cellular lysates. The glucose consumption, lactate levels and the lactate dehydrogenase activity were measured respectively using colorimetric/fluorometric and ELISA kits. The effects of metformin in AMP-activated protein kinase (AMPK) activation was assessed by mitochondrial complex I activity kits. Collagen I, α-smooth muscle actin (α-SMA) and collagen III were used as markers of collagen synthesis, which was measured using western blotting, whereas phosphorylated (p-) AMPK, AMPK, 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) and mTOR were detected by western blotting. Metformin significantly decreased mitochondrial complex I activity and upregulated the expression of p-AMPK/AMPK protein in a concentration-dependent manner. Furthermore, the aerobic glycolysis mediated by PFKFB3 and collagen synthesis in LPS-treated MRC-5 cells was gradually inhibited with increasing concentrations of metformin. However, this inhibitory role of metformin on PFKFB3-meditaed aerobic glycolysis and collagen synthesis was prevented by treatments with 3BDO and compound C, which are specific mTOR activator and AMPK inhibitor, respectively. Taken together, the findings from this study suggested that metformin may prevent PFKFB3-associated aerobic glycolysis from enhancing collagen synthesis in lung fibroblasts via regulating the AMPK/mTOR pathway.

MicroRNA-877-5p alleviates ARDS via enhancing PI3K/Akt path by targeting CDKN1B both in vivo and in vitro

Acute respiratory distress syndrome (ARDS) is a public health problem with high morbidity and mortality worldwide due to lacking known characteristic biomarkers and timely intervention. Pulmonary edema caused by inflammation and pulmonary microvascular endothelial cell disfunction is the main pathophysiological change of ARDS. Circulating microRNAs (miRNAs) are differentially expressed between subjects who did and did not develop ARDS. Many miRNAs have been exemplified to be involved in ARDS and could represent the novel therapeutic targets, but the role of microRNA-877-5p (miR-877-5p) in ARDS and its regulatory mechanisms are still unknown. Herein, we explore the underlying function of miR-877-5p toward anesis of ARDS and addressed that miRNA-877 can reduce the release of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6 thus attenuating the damage of pulmonary microvascular endothelial cells (HPMECs). Have further evaluated the protein expression, we detected that miR-877-5p contributed to the relief of ARDS by suppressing Cyclin-dependent kinase inhibitor 1B (CDKN1B), which serves as a regulator of endothelial cell polarization and migration through phosphatidylinositol-3-kinase and AKT (PI3K/Akt) signaling pathway. Besides, we noticed that CDKN1B restrains cell differentiation by inhibiting Cdk2 (cyclin-dependent kinase 2), instead of Cdk4 (cyclin-dependent kinase 4), during which the nuclear translocation of CDKN1B may participate. Together, our works testified that miR-877-5p might suppress inflammatory responses and promote HPMECs regeneration via targeting CDKN1B by modulation of Cdk2 and PI3K/Akt path. These molecules likely modulating ARDS progression may inform biomarkers and therapeutic development.

Neuron-specific enolase serum levels in COVID-19 are related to the severity of lung injury

The multifunctional role of neuron-specific enolase (NSE) in lung diseases is well established. As the lungs are greatly affected in COVID-19, we evaluated serum NSE levels in COVID-19 patients with and without dyspnea. In this study, we evaluated both SARS-CoV-2-infected and uninfected patients aged >18 years who were referred to hospitals in Catanzaro, Italy from March 30 to July 30, 2020. Epidemiological, clinical, and radiological characteristics, treatment, and outcome data were recorded and reviewed by a trained team of physicians. In total, 323 patients (178 men, 55.1% and 145 women, 44.9%) were enrolled; of these, 128 were COVID-19 patients (39.6%) and 195 were control patients (60.4%). Westergren’s method was used to determine erythroid sedimentation rate. A chemiluminescence assay was used for measurement of interleukin-6, procalcitonin, C-reactive protein, and NSE. We detected significantly higher NSE values (P<0.05) in COVID-19 patients than in controls. Interestingly, within the COVID-19 group, we also observed a further significant increase in dyspnea (Dyspnea Scale and Exercise score: 8.2 ± 0.8; scores ranging from 0 to 10, with higher numbers indicating very severe shortness of breath). These data provide the background for further investigations into the potential role of NSE as a clinical marker of COVID-19 progression.

Intragastric and atomized administration of canagliflozin inhibit inflammatory cytokine storm in lipopolysaccharide-treated sepsis in mice: A potential COVID-19 treatment

To date, drugs to attenuate cytokine storm in severe cases of Corona Virus Disease 2019 (COVID-19) are not available. In this study, we investigated the effects of intragastric and atomized administration of canagliflozin (CAN) on cytokine storm in lung tissues of lipopolysaccharides (LPS)-induced mice. Results showed that intragastric administration of CAN significantly and widely inhibited the production of inflammatory cytokines in lung tissues of LPS-induced sepsis mice. Simultaneously, intragastric administration of CAN significantly improved inflammatory pathological changes of lung tissues. Atomized administration of CAN also exhibited similar effects in LPS-induced sepsis mice. Furthermore, CAN significantly inhibited hypoxia inducible factor 1α (HIF-1α) and phosphofructokinase-2/fructose-2,6-bisphosphatase 3 (PFKFB3) protein levels in LPS-treated lung tissues. These results indicated that CAN might attenuate cytokine storm and reduce the inflammatory symptoms in critical cases in COVID-19. Its action mechanism might involve the regulation of HIF-1α and glycolysis in vivo. However, further studies about clinical application and mechanism analysis should be validated in the future.

Activation of TREM-1 induces endoplasmic reticulum stress through IRE-1α/XBP-1s pathway in murine macrophages

Increasing evidence suggests that endoplasmic reticulum (ER) stress activates several pro-inflammatory signaling pathways in many diseases, including acute lung injury (ALI). We have reported that blocking triggering receptor expressed on myeloid cells 1 (TREM-1) protects against ALI by suppressing pulmonary inflammation in mice with ALI induced by lipopolysaccharides (LPS). However, the molecular mechanism underlying the TREM-1-induced pro-inflammatory microenvironment in macrophages remains unclearly. Herein, we aimed to determine whether TREM-1 regulates the inflammatory responses induced by LPS associated with ER stress activation. We found that the activation of TREM-1 by a monoclonal agonist antibody (anti-TREM-1) increased the mRNA and protein levels of IL-1β, TNF-α, and IL-6 in primary macrophages. Treatment of the anti-TREM-1 antibody increased the expression of ER stress markers (ATF6, PERK, IRE-1α, and XBP-1s) in primary macrophages. While pretreatment with 4-PBA, an inhibitor of ER stress, significantly inhibited the expression of ER stress markers and pro-inflammatory cytokines and reduced LDH release. Furthermore, inhibiting the activity of the IRE-1α/XBP-1s pathway by STF-083010 significantly mitigated the increased levels of IL-1β, TNF-α, and IL-6 in macrophages treated by the anti-TREM-1 antibody. XBP-1 silencing attenuated pro-inflammatory microenvironment evoked by activation of TREM-1. Besides, we found that blockade of TREM-1 with LR12 ameliorated ER stress induced by LPS in vitro and in vivo. In conclusion, we conclude that TREM-1 activation induces ER stress through the IRE-1α/XBP-1s pathway in macrophages, contributing to the pro-inflammatory microenvironment.

NLRP3 as a sensor of metabolism gone awry

The NLRP3 inflammasome is an important player in innate immunity and pathogenic inflammation. Numerous studies have implicated it in sensing endogenous danger signals, yet the precise mechanisms remain unknown. Here, we review the current knowledge on the organismal and cellular metabolic triggers engaging NLRP3, and the mechanisms involved in integrating the diverse signals.

Mitigation of radiation-induced pulmonary fibrosis by small-molecule dye IR-780

Radiation-induced pulmonary fibrosis (RIPF) is a common complication during thoracic radiotherapy, but there are few effective treatments. Here, we identify IR-780, a mitochondria-targeted near-infrared (NIR) dye, can selectively accumulate in the irradiated lung tissues. Besides, IR-780 significantly alleviates radiation-induced acute lung injury and fibrosis. Furthermore, our results show that IR-780 prevents the differentiation of fibroblasts and the release of pro-fibrotic factors from alveolar macrophages induced by radiation. Besides, IR-780 downregulates the expression of glycolysis-associated genes, and 2-Deoxy-d-glucose (2-DG) also prevents the development of fibrosis in vitro, suggesting radioprotective effects of IR-780 on RIPF might be related to glycolysis regulation. Finally, IR-780 induces tumour cell apoptosis and enhances radiosensitivity in representative H460 and A549 cell lines. These findings indicate that IR-780 is a potential therapeutic small-molecule dye during thoracic radiotherapy.

Iridin Prevented Against Lipopolysaccharide-Induced Inflammatory Responses of Macrophages via Inactivation of PKM2-Mediated Glycolytic Pathways

Purpose

Abnormal glycolysis of immune cells contributed to the development of inflammatory response. Inhibition of this Warburg phenotype could be a promising strategy for preventing various inflammatory diseases. Iridin (IRD) is a natural isoflavone, and exerts anticancer, antioxidant, and anti-inflammatory effects. However, the underlying mechanism of IRD on acute inflammation remains unknown. In this study, the protective effects of IRD against lipopolysaccharide (LPS)-induced inflammation were investigated in murine macrophage RAW264.7 cells and in mice.

Methods

The inhibition of IRD on NO production in culture medium was detected by Griess assay while the levels of TNF-α, IL-1β, and MCP-1 were detected by ELISA assay. The effects of IRD on OCR and ECAR levels in LPS-treated macrophages were monitored by using Seahorse Analyzer. The apoptosis rate as well as the release of ROS and NO of RAW264.7 cells were analyzed by flow cytometric assay. The protective effects of IRD were investigated on LPS-induced inflammation in mice. The expressions of PKM2 and its downstream (p-JAK1, p-STAT1, p-STAT3, p-p65, iNOS, and COX2) in cells and in lung tissues were detected by Western blotting analysis.

Results

IRD treatment at the concentrations of 12.5-50 μM significantly inhibited the productions of TNF-α, IL-1β, MCP-1, and ROS, and suppressed the levels of glucose uptake and lactic acid in LPS-treated RAW264.7 cells. Oral administration with IRD (20-80 mg/kg) inhibited LPS-induced acute lung injury as well as inflammatory cytokine production in mice. Moreover, IRD targeted pyruvate kinase isozyme type M2 (PKM2) and suppressed its downstream p-JAK1, p-STAT1, p-STAT3, p-p65, iNOS, and COX2, which could be abolished by PKM2 agonist DASA-58 and antioxidant N-acetyl-L-cysteine, but partly be reversed by NF-κB activator CUT129 and JAK1 activator RO8191.

Conclusion

IRD alleviated LPS-induced inflammation through suppressing PKM2-mediated pathways, and could be a potential candidate for the prevention of inflammatory diseases.

Lycium barbarum Polysaccharide Antagonizes LPS-Induced Inflammation by Altering the Glycolysis and Differentiation of Macrophages by Triggering the Degradation of PKM2

Lipopolysaccharide (LPS)-induced inflammation is the leading cause of multiple organ failure in sepsis. Pyruvate kinase 2 (PKM2) is a protein kinase and transcriptional coactivator that plays an important role in glycolysis. Recent studies have confirmed that glycolysis maintains the M1 differentiation and induces immune activation in macrophages. Lycium barbarum polysaccharide (LBP), the main bioactive component of Chinese wolfberry, suppresses glycolysis and inflammation. Here, RAW264.7 macrophages were treated with LBP for evaluating its effects against LPS-induced inflammation. The differentiation of M1/M2 macrophages was assessed by flow cytometry for assessing the cell surface markers, CD86 and CD206. The enrichment of hypoxia inducible factor (HIF)-1α and ubiquitin in the PKM2 protein complex was determined by co-immunoprecipitation. LBP suppressed LPS-induced glycolysis, differentiation of M1 macrophages, and the production of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and high mobility group (HMG) 1 proteins. The suppressive effects of LBP were similar to those of PKM2 knockdown, but were abolished by the overexpression of PKM2. LPS elevated the mRNA and protein levels of PKM2. LBP reduced the LPS-induced expression of PKM2 protein, but had no effects on the expression of PKM2 mRNA. LPS inhibited the ubiquitination of PKM2, probably by downregulating the expression of ubiquitin ligases, including Nedd4L, Nedd4, and Gnb2. LBP interfered with the inhibition of PKM2 ubiquitination by upregulating the expression of Nedd4L, Nedd4, and Gnb2. In conclusion, LBP suppressed the LPS-induced inflammation by altering glycolysis and the M1 differentiation of macrophages. The effects of LBP were mediated by the downregulation of PKM2 via enhanced ubiquitination.

Time-course transcriptome analysis of lungs from mice exposed to ricin by intratracheal inoculation

In this study, a ricin toxin (RT)-induced pulmonary intoxication model was established in mice by intratracheal-delivered RT at a dose of 2× LD₅₀. Based on this model, the histopathological evaluation of the lungs at 24 h and 48 h post-exposure was executed, and the genome-wide transcriptome of the lungs at 4, 12, 24 and 48 h post-exposure was analyzed. Histopathological analysis showed that a large number of neutrophils infiltrated the lungs at 24 h post-exposure, and slight pulmonary edema and perivascular-peribronchiolar edema appeared in the lungs at 48 h. Transcriptome analysis showed that the expression of a large number of genes related to leukocyte migration and chemotaxis consistently increased in the lungs upon exposure to RT, and the expression of genes that participate in acute phase immune and/or inflammatory response, also increased within 12 h of exposure to RT, which could be confirmed by the measurement of cytokines, such as IL-1β, TNF-α and IL-6, in bronchoalveolar lavage fluid. While the expression of genes related to cellular components of the extracellular matrix and cell membrane integrity consistently decreased in the lungs, and the expression of genes related to antioxidant activity also decreased within the first 12 h. There are 17 differentially expressed genes (DEGs) that participate in ribotoxic stress response, endoplasmic reticulum stress response or immune response in the lungs at 4 h post-exposure. The expression of these DEGs was upregulated, and the number of these DEGs accounted for about 59 % of all DEGs at 4 h. The 17 DEGs may play an important role in the occurrence and development of inflammation. Notably, Atf3, Egr1, Gdf15 and Osm, which are poorly studied, may be important targets for the subsequent research of RT-induced pulmonary intoxication. This study provides new information and insights for RT-induced pulmonary intoxication, and it can provide a reference for the subsequent study of the toxicological mechanism and therapeutic approaches for RT-induced pulmonary intoxication.

Stat2-Drp1 mediated mitochondrial mass increase is necessary for pro-inflammatory differentiation of macrophages

Macrophage recruitment and pro-inflammatory differentiation are hallmarks of various diseases, including infection and sepsis. Although studies suggest that mitochondria may regulate macrophage immune responses, it remains unclear whether mitochondrial mass affects macrophage pro-inflammatory differentiation. Here, we found that lipopolysaccharide (LPS)-activated macrophages possess higher mitochondrial mass than resting cells. Therefore, this study aimed to explore the functional role and molecular mechanisms of increased mitochondrial mass in pro-inflammatory differentiated macrophages. Results show that an increase in the mitochondrial mass of macrophages positively correlates with inflammatory cytokine generation in response to LPS. RNA-seq analysis revealed that LPS promotes signal transducers and activators of transcription 2 (Stat2) and dynamin-related protein 1 (Drp1) expression, which are enriched in positive mitochondrial fission regulation. Meanwhile, knockdown or pharmacological inhibition of Drp1 blunts LPS-induced mitochondrial mass increase and pro-inflammatory differentiation. Moreover, Stat2 boosts Drp1 phosphorylation at serine 616, required for Drp1-mediated mitochondrial fission. LPS also causes Stat2-and Drp1-dependent biogenesis, which contributes to the generation of additional mitochondria. However, these mitochondria are profoundly remodeled, displaying fragmented morphology, loose cristae, reduced Δψm, and metabolic programming. Furthermore, these remodeled mitochondria shift their function from ATP synthesis to reactive oxygen species (ROS) production, which drives NFκB-dependent inflammatory cytokine transcription. Interestingly, an increase in mitochondrial mass with constitutively active phosphomimetic mutant of Drp1 (Drp1^S616E) boosted pro-inflammatory response in macrophages without LPS stimulation. In vivo, we also demonstrated that Mdivi-1 administration inhibits LPS-induced macrophage pro-inflammatory differentiation. Importantly, we observed Stat2 phosphorylation and Drp1-dependent mitochondrial mass increase in macrophages isolated from LPS-challenged mice. In conclusion, we comprehensively demonstrate that a Stat2-Drp1 dependent mitochondrial mass increase is necessary for pro-inflammatory differentiation of macrophages. Therefore, targeting the Stat2-Drp1 axis may provide novel therapeutic approaches for treating infection and inflammatory diseases.