Ablation of endothelial Pfkfb3 protects mice from acute lung injury in LPS-induced endotoxemia

Transcriptional signatures of endothelial cells shape immune responses in cardiopulmonary health and disease

The cardiopulmonary vasculature and its associated endothelial cells (ECs) play an essential role in sustaining life by ensuring the delivery of oxygen and nutrients. Beyond these foundational functions, ECs serve as key regulators of immune responses. Recent advances in single-cell RNA sequencing have revealed that the cardiopulmonary vasculature is composed of diverse EC subpopulations, some of which exhibit specialized immunomodulatory properties. Evidence for immunomodulation includes distinct expression profiles associated with antigen presentation, cytokine secretion, immune cell recruitment, translocation, and clearance - functions critical for maintaining homeostasis in the heart and lungs. In cardiopulmonary diseases, ECs undergo substantial transcriptional reprogramming, leading to a shift from homeostasis to an activated state marked by heightened immunomodulatory activity. This transformation has highlighted the critical role for ECs in disease pathogenesis and their potential as future therapy targets. This Review emphasizes the diverse functions of ECs in the heart and lungs, particularly adaptive and maladaptive immunoregulatory roles in cardiopulmonary health and disease.

Fruit of Physalis angulata L. and anti-inflammatory potential: An in silico, in vitro, and in vivo study focusing on PFKFB3

BACKGROUND

Sepsis-associated lung injury (SALI) is a disease characterised by inflammation. The fruit of Physalis angulata L. has been employed as a premium, novel, nutritious, healthcare "herbal fruit", which can be processed into juice, preserved fruit, canned food, and so forth.

PURPOSE

The objective of this study is to examine the impact of the fruit of Physalis angulata L. on the inhibition of inflammation in sepsis-associated lung injury and to elucidate the underlying mechanisms.

METHODS

The active components of fruit of Physalis angulata L. were analysed using HPLC-MS/MS. A comprehensive investigation was conducted to elucidate the effects and regulatory mechanisms of fruit of Physalis angulata L. on sepsis-associated lung injury and M1 polarisation of macrophage in mice subjected to acute LPS treatment. The renoprotective effect of fruit of Physalis angulata L. on LPS-treated mice was evaluated by measuring tissue damage and inflammation. In addition, we employed RNA-seq methodologies to analyse the principal regulatory targets of fruit of Physalis angulata L.. Furthermore, the expression of key proteins and markers of inflammation and glucose metabolism, as well as the levels of key indicators related to M1 polarisation of macrophage, were examined by immunoblotting, immunohistochemistry, immunoprecipitation, quantitative real-time PCR (qPCR) and specific probes.

RESULTS

In murine models, the ethanol extract of the fruit of Physalis angulata L. (EPAF) has been demonstrated to effectively inhibit structural damage and inflammation in the lung tissue of a murine model of LPS-induced acute lung injury. In terms of its mechanism of action, EPAF may inhibit M1 polarisation of macrophage and excessive inflammation by modulating the acetylation and phosphorylation of PFKFB3. This in turn affects glycolysis and the subsequent activation of NF-κB, HIF-1α and STAT3 in macrophages. Furthermore, the capacity of EPAF to markedly diminish LPS-induced lung injury in a murine model indicates that it may serve as a promising adjunctive therapy for acute lung Injury.

CONCLUSION

These suggest that fruit of Physalis angulata L. alleviates sepsis-associated lung injury through suppressing M1 polarization of macrophage via regulation of PFKFB3.

NLRP3 Inflammasome-mediated pyroptosis in acute lung injury: Roles of main lung cell types and therapeutic perspectives

The NLRP3 inflammasome plays a pivotal role in the pathogenesis of acute lung injury (ALI) by regulating pyroptosis, a highly inflammatory form of programmed cell death. NLRP3-mediated pyroptosis leads to alveolar epithelial cell injury, increased pulmonary microvascular endothelial permeability, excessive alveolar macrophage activation, and neutrophil dysfunction, collectively driving ALI progression. In addition to the classical NLRP3-dependent pathway, the non-canonical pyroptosis pathway (caspase-4/5/11) also contributes to ALI by inducing pyroptotic cell death in AECs and ECs, further amplifying NLRP3 activation through damage-associated molecular patterns (DAMP) release. Moreover, neutrophils (NE) pyroptosis exhibits dual roles in ALI, as it enhances pathogen clearance but also exacerbates excessive inflammation and tissue damage, highlighting the complexity of its regulation. Targeting the NLRP3 inflammasome and pyroptotic pathways has emerged as a promising therapeutic strategy for ALI. Various NLRP3 inhibitors (e.g., MCC950, CY-09, OLT1177) and pyroptosis inhibitors have demonstrated significant anti-inflammatory and tissue-protective effects in preclinical models. However, the clinical translation of NLRP3-targeted therapies remains challenging due to off-target effects, potential immunosuppression, lack of patient stratification strategies, and compensatory activation of alternative inflammasomes (e.g., AIM2, NLRC4). Future studies should focus on optimizing the selectivity of NLRP3 inhibitors, developing personalized therapeutic approaches, and exploring combination strategies to enhance their clinical applicability in ALI.

Heme Oxygenase-1 Modulates Macrophage Polarization Through Endothelial Exosomal miR-184-3p and Reduces Sepsis-Induce Lung Injury

Introduction

Pulmonary microvascular endothelial cells (PMVECs) are notably implicated in the pathogenesis of sepsis-induced lung injury. Exosomes derived from PMVECs facilitate intercellular communication among various cell types, especially crosstalk with macrophages. Heme oxygenase-1 (HO-1), an early stress-responsive enzyme with inherent protective functions, has been implicated in acute lung injury (ALI) mitigation. But research on the mechanism of HO-1 in macrophage polarization via PMVEC exosomes in sepsis-induced lung injury is lacking.

Methods

To investigate the role of HO-1 in the interaction between endothelial cells and macrophages, HO-1 knockout mouse model were established. Exosomes from PMVECs were isolated, and differential expression of microRNA (miRNA) was determined by sequencing. An in vitro co-culture system involving Murine Alveolar Macrophage Cell Line (MH-S cells) and HO-1/ PMVECs-derived exosomes (HP-exos) was used to investigate the underlying mechanisms. To further verify the involvement of HO-1 in intercellular communication through exosomal miRNA in vivo, the level of pulmonary inflammation was evaluated, and the polarization of pulmonary macrophages was analyzed.

Results

The results showed that miR-184-3p was significantly downregulated in HP-exos, and supplementation of miR-184-3p enhanced the polarization of M1 macrophages, thus intensifying lung inflammation. HO-1 regulates the polarization of macrophages by regulating endothelial exosomes. Overexpression of HO-1 downregulates miR-184-3p, which negatively regulates Semaphorin 7A (Sema7a), which attenuated M1 type macrophages (M1) polarization and augmented M2 type macrophages (M2) polarization, thereby partially mitigating lung injury and inflammation.

Conclusion

Collectively, we elucidated a novel potential therapeutic mechanism that HO-1 alleviate inflammation by modulating the M1/M2 ratio in sepsis-induced ALI by regulating miR-184-3p/Sema7a expression.

ITGB2 and ICAM3 predict increased survival of sepsis with decreased intercellular communication in cytotoxic CD8+ T cells

Sepsis is closely linked to immunity. Our research aimed to identify key genes associated with sepsis immunity utilizing single-cell RNA sequencing (scRNA-seq) data. This study obtained the GSE167363 and GSE54514 datasets from the Gene Expression Omnibus (GEO). The GSE167363 dataset was subjected to cluster analysis, cell proportion analysis, cell interaction analysis, and gene set enrichment analysis (GSEA). The differentially expressed genes (DEGs) of CD8+ T cells were intersected with the DEGs in the GSE54514 dataset, and key genes related to immunity in sepsis patients were identified through Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Finally, we validated the gene expression levels in a mouse model of sepsis caused by cecum ligation and puncture (CLP). Findings indicated that intercellular communication of Cytotoxic CD8+ T cells was reduced in the sepsis survivors compared to non-survivors. The expression of 3 down-regulated key DEGs (ITGB2, SELL and ICAM3) was negatively correlated with the abundance of CD8+ T cells. Moreover, Cytotoxic CD8+ T cells with low expression of ITGB2, SELL and ICAM3 were more adverse to the survival of sepsis as compared to those with high expression of the above genes. These genes may predict increased survival in sepsis by regulating intercellular communication in cytotoxic CD8+ T cells, suggesting that they are potential therapeutic targets for improving sepsis prognosis.

E3 Ubiquitin Ligase TRIM7 Alleviates Lipopolysaccharide-Induced Acute Lung Injury via Inhibiting NLRP3 Inflammasome Activation

Acute lung injury (ALI) is a common clinical disease with high mortality, characterized by tissue damage caused by excessive activation of inflammation. TRIM7 is an E3 ligase that plays an important role in regulating viral infection, tumor progression, and innate immune response. However, its function in ALI is unclear. In this study, lipopolysaccharide (LPS) was used to stimulate C57BL/6j mice and HULEC-5a cells to establish ALI models in vivo and in vitro. TRIM7 expression was down-regulated during ALI. Furthermore, overexpressing TRIM7 in HULEC-5a cells relieved cell damage and inflammatory activation induced by LPS stimulation. TRIM7 knockdown had the opposite effect. Trim7-overexpressing mice were established by endotracheal injection of adeno-associated virus 6-Trim7 virus in vivo; the ALI model was then induced by LPS stimulation. Overexpression of TRIM7 could alleviate lung tissue injury, pulmonary interstitial hemorrhage, increased alveolar and vascular permeability, inflammatory cell infiltration, and secretion of inflammatory factors induced by LPS stimulation. Mechanistically, TRIM7 inhibited the expression of NOD-, LRR- and pyrin domain-containing 3 (NLRP3) and the activation of the NLRP3 inflammasome. The regulatory effect of TRIM7 on ALI depended on the NLRP3 inflammasome. This investigation, for the first time, showed the inhibitory effect of TRIM7 on ALI and activation of the NLRP3 inflammasome, providing new targets and ideas for the research on the mechanism and treatment of ALI.

The Marine Compound Isaridin E Ameliorates Lipopolysaccharide-Induced Vascular Endothelial Inflammation via the Downregulation of the TLR4/NF-κB Signaling Pathway

Isaridin E, a cyclodepsipeptide derived from the marine fungus Beauveria felina (SYSU-MS7908), has been demonstrated to possess multiple biological properties. In this study, we employed both lipopolysaccharide (LPS)-stimulated human umbilical vein endothelial cells (HUVECs) and a LPS-induced murine endotoxemia model to investigate its anti-inflammatory effects. Our results revealed that isaridin E suppressed the expression of pro-inflammatory cytokines and adhesion molecules in a concentration dependent manner, while also reducing monocyte adhesion to endothelial cells. Furthermore, this compound attenuated vascular hyperpermeability and inflammatory cell infiltration in the lungs, as well as preserving the integrity of the aortic and pulmonary tissues. At the molecular level, isaridin E was found to downregulate TLR4 expression, increase IκBα levels, and inhibit the LPS-induced phosphorylation and nuclear translocation of NF-κB p65. In conclusion, our findings indicate that isaridin E exerts robust anti-inflammatory effects in LPS-induced endotoxemia through the suppression of the TLR4/NF-κB signaling axis, positioning it as a promising therapeutic candidate for vascular inflammatory disorders.

Houshiheisan modulates the NF-κB/MLCK signaling pathway to protect the endothelial barrier in cerebral small vessel disease

ETHNOPHARMACOLOGICAL RELEVANCE

Houshiheisan (HSHS) is a classical prescription remedy for cerebral small vessel disease (CSVD) in traditional Chinese medicine; however, its specific ingredients and mechanisms remain unclear.

AIM OF THE STUDY

This study sought to elucidate the protective effects of HSHS on spontaneously hypertensive rats (SHR) subjected to unilateral common carotid artery occlusion (UCCAO), referred to as SHR-UCCAO, and to identify potential targets and mechanistic pathways involved in CSVD treatment using serum pharmacochemistry, network pharmacology, and experimental validation.

MATERIALS AND METHODS

Serum pharmacochemistry was used to identify the components of HSHS. Network and functional enrichment analyses were performed to clarify the targets and biological mechanisms of HSHS. The CB-DOCK2 database was employed for molecular docking of the principal compounds and core target proteins. As predicted by network pharmacological analysis, the potential mechanisms of HSHS against CSVD were experimentally validated in a CSVD rat model and endothelial cells subjected to oxygen-glucose deprivation.

RESULTS

A total of 50 compounds in serum samples from HSHS were identified as potential active agents. Network pharmacology and molecular docking analyses revealed that HSHS could treat CSVD via multiple components and targets. In animal experiments, HSHS ameliorated systolic and diastolic blood pressure, improved gait disturbance, and reduced the Albumin levels in the affected cortex of CSVD rats. Animal and cell experiments demonstrated that HSHS improved the endothelial barrier injury and upregulated the expression of ZO-1, Occludin, Claudin-5, and VE-Cadherin through regulation of the NF-κB/MLCK pathway.

CONCLUSIONS

This study indicated that HSHS could protect the endothelial barrier in CSVD by modulating the NF-κB/MLCK signaling pathway.

Micheliolide attenuates sepsis-induced acute lung injury by suppressing mitochondrial oxidative stress and PFKFB3-driven glycolysis

BACKGROUND

Sepsis is a potentially fatal condition with a significant risk of death. Acute lung injury (ALI) is a life-threatening complication of sepsis, and the inflammatory response plays a critical role in sepsis-induced ALI. The protective effects of micheliolide (MCL) against renal fibrosis and leukemia have been demonstrated, but the precise underlying mechanisms remain unclear.

METHODS

In vitro, lipopolysaccharides (LPS) and interferon-gamma (IFN-γ) were used to stimulate RAW264.7 cells and bone marrow-derived macrophages (BMDMs) to investigate the protective effect of MCL on sepsis-induced ALI. Cecal ligation and puncture (CLP) models were constructed in mice to induce ALI in vivo. The expression of inflammatory factors, macrophage polarization markers, and the glycolysis-related enzyme 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) were measured in vivo. Mitochondrial function, oxidative stress, and mitochondrial-related proteins were evaluated in vitro.

RESULTS

MCL inhibited CLP-induced ALI, as evidenced by improvements in proinflammatory factor levels, lung wet/dry ratios, and histopathological findings. In vitro, MCL treatment significantly suppressed LPS + IFN-γ-induced M1-type polarization of RAW264.7 cells and BMDMs, as well as the production of inflammatory factors and oxidative stress. Mechanistic experiments revealed that MCL suppresses PFKFB3-driven glycolysis to reduce inflammation and activates the mitochondrial unfolded protein response (UPRmt) to alleviate mitochondrial stress. However, the therapeutic effect of MCL was diminished when PFKFB3 was overexpressed in cells.

CONCLUSION

This study is the first to demonstrate that MCL attenuates sepsis-induced ALI by reducing M1-type macrophage polarization. Its therapeutic effect is closely related to the suppression of oxidative stress and PFKFB3-driven glycolysis.

Glycolysis in Peritubular Endothelial Cells and Microvascular Rarefaction in CKD

Key Points

Peritubular endothelial cells have a hypoglycolytic metabolism in CKD. Restoration of glycolysis in CKD peritubular endothelial cells by overexpressing 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase attenuates microvascular rarefaction and kidney fibrosis. Strategies targeting the metabolic defect in glycolysis in peritubular endothelial cells may be effective in the treatment of CKD.

Background

Peritubular endothelial cell dropout leading to microvascular rarefaction is a common manifestation of CKD. The role of metabolism reprogramming in peritubular endothelial cell loss in CKD is undetermined.

Methods

Single-cell sequencing and metabolic analysis were used to characterize the metabolic profile of peritubular endothelial cells from patients with CKD and from CKD mouse models. In vivo and in vitro models demonstrated metabolic reprogramming in peritubular endothelial cells in conditions of CKD and its contribution to microvascular rarefaction.

Results

In this study, we identified glycolysis as a top dysregulated metabolic pathway in peritubular endothelial cells from patients with CKD. Specifically, CKD peritubular endothelial cells were hypoglycolytic while displaying an antiangiogenic response with decreased proliferation and increased apoptosis. The hypoglycolytic phenotype of peritubular endothelial cells was recapitulated in CKD mouse models and in peritubular endothelial cells stimulated by hydrogen peroxide. Mechanically, oxidative stress, through activating a redox sensor kruppel-like transcription factor 9, downregulated the glycolytic activator 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase expression, thereby reprogramming peritubular endothelial cells toward a hypoglycolytic phenotype. 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase overexpression in peritubular endothelial cells restored hydrogen peroxide–induced reduction in glycolysis and cellular ATP levels and enhanced the G1/S cell cycle transition, enabling peritubular endothelial cells to improve proliferation and reduce apoptosis. Consistently, restoration of peritubular endothelial cell glycolysis in CKD mice, by overexpressing endothelial Pfkfb3, reversed the antiangiogenic response in peritubular endothelial cells and protected the kidney from microvascular rarefaction and fibrosis. By contrast, suppression of glycolysis by endothelial Pfkfb3 deletion exacerbated microvascular rarefaction and fibrosis in CKD mice.

Conclusions

Our study revealed a disrupted regulation of glycolysis in peritubular endothelial cells as an initiator of microvascular rarefaction in CKD. Restoration of peritubular endothelial cell glycolysis in CKD kidney improved microvascular rarefaction and ameliorated fibrotic lesions.

Targeting SphK1/S1PR3 axis ameliorates sepsis-induced multiple organ injury via orchestration of macrophage polarization and glycolysis

Sepsis is a heterogeneous and imprecise disorder characterized by aberrant response to infection which has been accredited for detrimental impact on immune homeostasis. Recently, macrophage metabolism has been recognized as attractive targets to develop novel immunomodulatory therapy for sepsis research. However, the fine-tuning regulators dictating macrophage functions and the specific mechanisms underlying macrophage metabolic reprogramming remain largely obscure. Sphingosine-1-phosphate (S1P), a metabolic mediator of sphingolipid catabolism, predominantly formed through sphingosine kinase 1 (SphK1) catalyzing, mediates inflammation in sepsis by binding to S1P receptor 3 (S1PR3) expressed in macrophages. Here we demonstrate that SphK1/S1PR3 axis was upregulated in lipopolysaccharide (LPS)-induced macrophages and septic mice lungs, cascading the activation of proglycolytic signaling such as HIF-1α, HK2 and PFKFB3. Targeted inhibition of Sphk1 by PF-543 effectively abrogated upregulated SphK1/S1PR3 axis in vitro and in vivo. In addition, PF-543 significantly suppressed sepsis-related inflammation and multi-organ injury in vivo. Furthermore, PF-543 not only blunted key glycolytic enzymes HIF-1α, HK2, and PFKFB3 in LPS-treated macrophages but also inhibited HK2 and PFKFB3 in septic mice. Silencing or inhibiting SphK1 tempered pro-inflammatory M1 macrophages while boosted anti-inflammatory M2 macrophages. Intriguingly, S1PR3 knockdown proficiently dampened glycolysis-associated markers, retrieved LPS-modulated M1/M2 polarization and attenuated NF-κB p65 activation. In conclusion, our study provides the first evidence that PF-543 orchestrates proportional imbalance of macrophage polarization and the Warburg effect in a SphK1/S1PR3 dependent manner during sepsis, mitigating both hyperinflammation and multi-organ failure, adding a novel puzzle piece to pharmacologically exploitable therapy for sepsis.

Baicalein suppresses inflammation and attenuates acute lung injury by inhibiting glycolysis via HIF‑1α signaling

Baicalein, a flavonoid monomer compound isolated from the dried root of the traditional Chinese herb Scutellaria baicalensis, has several pharmacological activities, such as anti‑inflammatory, anti‑angiogenic, antitumor, antimicrobial and antiviral properties. Acute lung injury (ALI) is characterized by injury of the alveolar epithelium and capillary endothelium, which results in decreased lung volume, decreased lung compliance, ventilation/perfusion mismatch, intrapulmonary edema, alveolar edema and even acute hypoxemic respiratory failure. The present study aimed to investigate the effects of baicalein on lung injury and inflammation. Bioinformatics analysis using network pharmacology predicted that the hypoxia inducible factor‑1α (HIF‑1α) and glycolysis signaling pathways were involved in the mechanism underlying the therapeutic effects of baicalein. Further in vitro and in vivo experiments, such as immunohistochemistry, immunofluorescence and PCR, verified that baicalein could inhibit HIF‑1α signaling, thus suppressing glycolysis, and improving inflammatory responses and ALI. Taken together, the results of the present study suggested that the anti‑inflammatory effects of baicalein on treating ALI were associated with its ability to suppress glycolysis via the HIF‑1α signaling pathway.

Deciphering Oxidative Stress in Cardiovascular Disease Progression: A Blueprint for Mechanistic Understanding and Therapeutic Innovation

Oxidative stress plays a pivotal role in the pathogenesis and progression of cardiovascular diseases (CVDs). This review focuses on the signaling pathways of oxidative stress during the development of CVDs, delving into the molecular regulatory networks underlying oxidative stress in various disease stages, particularly apoptosis, inflammation, fibrosis, and metabolic imbalance. By examining the dual roles of oxidative stress and the influences of sex differences on oxidative stress levels and cardiovascular disease susceptibility, this study offers a comprehensive understanding of the pathogenesis of cardiovascular diseases. The study integrates key findings from current research in three comprehensive ways. First, it outlines the major CVDs associated with oxidative stress and their respective signaling pathways, emphasizing oxidative stress's central role in cardiovascular pathology. Second, it summarizes the cardiovascular protective effects, mechanisms of action, and animal models of various antioxidants, offering insights into future drug development. Third, it discusses the applications, advantages, limitations, and potential molecular targets of gene therapy in CVDs, providing a foundation for novel therapeutic strategies. These tables underscore the systematic and integrative nature of this study while offering a theoretical basis for precision treatment for CVDs. A major contribution of this study is the systematic review of the differential effects of oxidative stress across different stages of CVDs, in addition to the proposal of innovative, multi-level intervention strategies, which open new avenues for precision treatment of the cardiovascular system.

ASIC1a regulates airway epithelial cell pyroptosis in acute lung injury by NLRP3-Caspase1-GSDMD pathway

BACKGROUND

Acidosis is the most common complication that seriously affects the prognosis of acute respiratory distress syndrome (ARDS). Acid-sensitive ion channel 1a (ASIC1a) is activated in acidic environments to regulate inflammatory process. However, the role of ASIC1a in ARDS is unclear.

METHODS

In this study, we examined the expression of ASIC1a in airway epithelial cells in an acidic environment. We then investigated whether blocking ASIC1a could inhibit pyroptosis of airway epithelial cells and the molecular mechanism. In the mouse acute lung injury (ALI) model, we observed the changes of lung histopathology, arterial blood gas and pyroptosis related indexes after ASIC1a inhibition. Bronchoalveolar lavage fluid (BALF) from patients with ARDS were collected to explore the expression level of ASIC1a in ARDS patients.

RESULTS

Inhibiting ASIC1a can reduce the airway epithelial cell pyroptosis induced by an extracellular acidic environment. ASIC1a can bind to PRKACA, and silencing ASIC1a and PRKACA can inhibit the occurrence of pyroptosis in airway epithelial cells. Compared with control group, arterial blood pH and PaO2 in ALI group were significantly reduced. The inflammation in the lungs is more intense, and the mRNA and protein of NLRP3, Caspase1 and GSDMD were increased, while ASIC1a specific blocker psalmotoxin-1 alleviated this phenomenon. The expression of ASIC1a in BALF of ARDS patients was significantly increased, especially in non-survival group.

CONCLUSION

Acidic micro-environment can induce the increased expression of ASIC1a, and inhibition of ASIC1a can alleviate the inflammation and airway epithelial cell pyroptosis in ARDS. ASIC1a may be a new target for the treatment of ARDS.

Intracellular endothelial cell metabolism in vascular function and dysfunction

Endothelial cells (ECs) form the inner lining of blood vessels that is crucial for vascular function and homeostasis. They regulate vascular tone, oxidative stress, and permeability. Dysfunction leads to increased permeability, leukocyte adhesion, and thrombosis. ECs undergo metabolic changes in conditions such as wound healing, cancer, atherosclerosis, and diabetes, and can influence disease progression. We discuss recent research that has revealed diverse intracellular metabolic pathways in ECs that are tailored to their functional needs, including lipid handling, glycolysis, and fatty acid oxidation (FAO). Understanding EC metabolic signatures in health and disease will be crucial not only for basic biology but can also be exploited when designing new therapies to target EC-related functions in different vascular diseases.

The impact of glucose metabolism on inflammatory processes in sepsis-induced acute lung injury

Acute lung injury (ALI) is a prevalent and critical complication of sepsis, marked by high incidence and mortality rates, with its pathogenesis still not being fully elucidated. Recent research has revealed a significant correlation between the metabolic reprogramming of glucose and sepsis-associated ALI (S-ALI). Throughout the course of S-ALI, immune cells, including macrophages and dendritic cells, undergo metabolic shifts to accommodate the intricate demands of immune function that emerge as sepsis advances. Indeed, glucose metabolic reprogramming in S-ALI serves as a double-edged sword, fueling inflammatory immune responses in the initial stages and subsequently initiating anti-inflammatory responses as the disease evolves. In this review, we delineate the current research progress concerning the pathogenic mechanisms linked to glucose metabolic reprogramming in S-ALI, with a focus on the pertinent immune cells implicated. We encapsulate the impact of glucose metabolic reprogramming on the onset, progression, and prognosis of S-ALI. Ultimately, by examining key regulatory factors within metabolic intermediates and enzymes, We have identified potential therapeutic targets linked to metabolic reprogramming, striving to tackle the inherent challenges in diagnosing and treating Severe Acute Lung Injury (S-ALI) with greater efficacy.

Shenfu injection ameliorates endotoxemia-associated endothelial dysfunction and organ injury via inhibiting PI3K/Akt-mediated glycolysis

ETHNOPHARMACOLOGICAL RELEVANCE

Microcirculatory dysfunction is one of the main characteristics of sepsis. Shenfu Injection (SFI) as a traditional Chinese medicine is widely applied in clinical severe conditions. Recent studies have shown that SFI has the ability to ameliorate sepsis-induced inflammation and to improve microcirculation perfusion.

AIM OF THE STUDY

This study aims to investigate the underlying mechanism of SFI for ameliorating sepsis-associated endothelial dysfunction and organ injury.

MATERIALS AND METHODS

Side-stream dark-field (SDF) imaging was used to monitor the sublingual microcirculation of septic patients treated with or without SFI. Septic mouse model was used to evaluate the effects of SFI in vivo. Metabolomics and transcriptomics were performed on endothelial cells to identify the underlying mechanism for SFI-related protective effect on endothelial cells.

RESULTS

SFI effectively abolished the disturbance and loss of sublingual microcirculation in septic patients. Twenty septic shock patients with or without SFI administration were enrolled and the data showed that SFI significantly improved the levels of total vessel density (TVD), perfused vessel density (PVD), microvascular flow index (MFI), and the proportion of perfused vessels (PPV). The administration of SFI significantly decreased the elevated plasma levels of Angiopoietin-2 (Ang2) and Syndecan-1, which are biomarkers indicative of endothelial damage in sepsis patients. In the mouse septic model in vivo, SFI inhibited the upregulation of endothelial adhesion molecules and Ly6G + neutrophil infiltration while restored the expression of VE-Cadherin in the vasculature of the lung, kidney, and liver tissue. Additionally, SFI reduced the plasma levels of Ang2, Monocyte Chemoattractant Protein-1(MCP1), and Interleukin-6 (IL6), and alleviated liver and kidney injury in septic mice. Moreover, SFI significantly inhibited the inflammatory activation and increased permeability of endothelial cells induced by endotoxins in vitro. By performing metabolomics and transcriptomics, we identified the activation of PI3K/Akt-mediated glycolysis as the underlying mechanism for SFI-related protective effect on endothelial cells.

CONCLUSIONS

Our findings revealed that SFI may improve microcirculation perfusion and endothelial function in sepsis via inhibiting PI3K/Akt-mediated glycolysis, providing theoretical evidence for the clinical application of SFI.

Isoechinulin B, a natural product from Antarctic fungus, attenuates acute liver injury by inhibiting excessive cell adhesion

Abnormal cell adhesion between leukocytes and endothelial cells is closely associated with the development of numerous inflammation-related diseases, with adhesion molecules playing a crucial role. The disruption of cell adhesion directly or indirectly inhibits excessive cell adhesion and thus produces a therapeutic effect. However, there are only a few clinically available antagonists of cell adhesion. One of the biggest challenges is the development of novel and efficient cell adhesion inhibitors. Recently, the anti-inflammatory pharmacological activity of natural products of microbial origin has also received increasing attention. Here, we obtained a potential cell adhesion inhibitor isoechinulin B, an indole diketopiperazine derivative, from the Antarctic fungus Aspergillus sp. CPCC 401072, which is active against cell adhesion. Isoechinulin B decreased the expression of vascular endothelial adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) by inhibiting the activation of the NF-κB signaling pathway, thereby inhibiting cell adhesion between leukocytes and endothelial cells to reduce macrophage infiltration in the liver and significantly attenuate lipopolysaccharide-induced acute liver injury in mice. CONCLUSION: Isoechinulin B is a novel cell adhesion inhibitor derived from fungi found in extreme environments.

Postischemic inactivation of HIF prolyl hydroxylases in endothelium promotes maladaptive kidney repair by inducing glycolysis

Ischemic acute kidney injury (AKI) is common in hospitalized patients and increases the risk for chronic kidney disease (CKD). Impaired endothelial cell (EC) functions are thought to contribute in AKI to CKD transition, but the underlying mechanisms remain unclear. Here, we identify a critical role for endothelial oxygen sensing prolyl hydroxylase domain (PHD) enzymes 1-3 in regulating postischemic kidney repair. In renal endothelium, we observed compartment-specific differences in the expression of the 3 PHD isoforms in both mice and humans. Postischemic concurrent inactivation of endothelial PHD1, PHD2, and PHD3 but not PHD2 alone promoted maladaptive kidney repair characterized by exacerbated tissue injury, fibrosis, and inflammation. scRNA-Seq analysis of the postischemic endothelial PHD1, PHD2, and PHD3-deficient (PHDTiEC) kidney revealed an endothelial hypoxia and glycolysis-related gene signature, also observed in human kidneys with severe AKI. This metabolic program was coupled to upregulation of the SLC16A3 gene encoding the lactate exporter monocarboxylate transporter 4 (MCT4). Strikingly, treatment with the MCT4 inhibitor syrosingopine restored adaptive kidney repair in PHDTiEC mice. Mechanistically, MCT4 inhibition suppressed proinflammatory EC activation, reducing monocyte-EC interaction. Our findings suggest avenues for halting AKI to CKD transition based on selectively targeting the endothelial hypoxia-driven glycolysis/MCT4 axis.

The role of the interplay between macrophage glycolytic reprogramming and NLRP3 inflammasome activation in acute lung injury/acute respiratory distress syndrome

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a severe respiratory condition associated with elevated morbidity and mortality. Understanding their complex pathophysiological mechanisms is crucial for developing new preventive and therapeutic strategies. Recent studies highlight the significant role of inflammation involved in ALI/ARDS, particularly the hyperactivation of the NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome in macrophages. This activation drives pulmonary inflammation by releasing inflammatory signalling molecules and is linked to metabolic reprogramming, marked by increased glycolysis and reduced oxidative phosphorylation. However, the relationship between NLRP3 inflammasome activation and macrophage glycolytic reprogramming in ALI/ARDS, as well as the molecular mechanisms regulating these processes, remain elusive. This review provides a detailed description of the interactions and potential mechanisms linking NLRP3 inflammasome activation with macrophage glycolytic reprogramming, proposing that glycolytic reprogramming may represent a promising therapeutic target for mitigating inflammatory responses in ALI/ARDS. KEY POINTS: NLRP3 inflammasome activation is pivotal in mediating the excessive inflammatory response in ALI/ARDS. Glycolytic reprogramming regulates NLRP3 inflammasome activation. Therapeutic potential of targeting glycolytic reprogramming to inhibit NLRP3 inflammasome activation in ALI/ARDS.

Sec13 promotes glycolysis by inhibiting Ubqln1 mediated Pgm1 ubiquitination in ALI

Acute lung injury (ALI) is a severe lung damage characterized by acute hypoxemia, increased pulmonary vascular permeability, and inflammatory reactions. Despite current treatments, mortality from ALI remains high. This study found that Sec13 is highly expressed in ALI and regulates it by glycolysis and epithelial-mesenchymal transition (EMT). In an ALI mouse model and cell model, Sec13 expression increased, accompanied by enhanced glycolysis, EMT, and inflammation. Sec13 knockdown suppressed these effects, alleviating ALI. Sec13 forms a protein complex with Pgm1, an enzyme regulating glucose-6-phosphate (G6P) production, and Ubqln1, an ubiquitin ligase. Sec13 inhibits Ubqln1-mediated Pgm1 ubiquitination, thereby stabilizing Pgm1. In ALI, Pgm1 binding to Sec13 increased but binding to Ubqln1 decreased. Sec13 knockdown decreased lactate, G6P, EMT markers, and inflammatory cytokines. Pgm1 knockdown produced similar effects. Ubqln1 overexpression suppressed inflammation but decreased Pgm1 expression. In conclusion, Sec13 plays a key role in ALI by inhibiting Ubqln1-mediated Pgm1 ubiquitination, affecting glycolysis and EMT. Sec13 and Pgm1 may be new targets for treating ALI.

SENP1 Promotes Caspase-11 Inflammasome Activation and Aggravates Inflammatory Response in Murine Acute Lung Injury Induced by Lipopolysaccharide

BACKGROUND

Infection is the leading cause of acute lung injury (ALI). Macrophages, which are pivotal innate immune cells, play a critical role in mediating inflammatory processes. Intracellular lipopolysaccharide (LPS) from invasive Gram-negative bacteria can activate the caspase-11 inflammasome, leading to the induction of pyroptosis in macrophages. This process subsequently triggers the release of inflammatory cytokines and damage-associated molecular patterns from pyroptotic macrophages, thereby exacerbating inflammatory progression in ALI. However, the precise regulatory mechanisms governing caspase-11 activation is still unclear. Sentrin-specific proteases (SENPs) have been identified as notable targets for their anti-inflammatory properties. Nevertheless, the specific role of SENPs in macrophage pyroptosis during the pathogenesis of ALI remains unknown.

METHODS

We used LPS as an endotoxin to induce ALI. We analyzed the expression and location of sentrin-specific protease 1 (SENP1), pulmonary impairment, macrophage infiltration, caspase-11 inflammasome expression and activation, caspase-11 SUMOylation, and inflammatory cytokine secretion.

RESULTS

Upregulated expression of SENP1 in lung tissue and macrophages was observed following LPS stimulation. SENP1 mediates de-SUMOylation and activation of caspase-11 inflammasome in macrophages. Moreover, pharmacological inhibition or genetic deficiency of SENP1 in macrophages significantly improved ALI-related histological damage by reducing the secretion of inflammatory cytokines and suppressing caspase-11-dependent pyroptosis.

CONCLUSIONS

Collectively, our findings highlight the involvement of SENP1 in caspase-11 activation and inflammatory progression in macrophages, thereby establishing a scientific foundation for the exploration of novel therapeutic strategies aimed at treating ALI.

rTM reprograms macrophages via the HIF-1α/METTL3/PFKM axis to protect mice against sepsis

The metabolic reprogramming of macrophages is a potential therapeutic strategy for sepsis treatment, but the mechanism underlying this reprogramming remains unclear. Since glycolysis can drive macrophage phenotype switching, the rate-limiting enzymes in glycolysis may be key to treating sepsis. Here, we found that, compared with other isoenzymes, the expression of 6-phosphofructokinase, muscle type (PFKM) was the most upregulated in monocytes from septic patients. Recombinant thrombomodulin (rTM) treatment downregulated the protein expression of PFKM in macrophages. Both rTM treatment and Pfkm knockout protected mice from sepsis and reduced the production of the proinflammatory cytokines IL-1β, IL-6, TNF-α, and IL-27, whereas PFKM overexpression increased the production of these cytokines. Mechanistically, rTM treatment inhibited glycolysis in macrophages by decreasing PFKM expression in a hypoxia-inducible factor-1α (HIF-1α)-dependent manner. HIF-1α overexpression increased methyltransferase-like 3 (METTL3) expression, elevated the m6A level on Pfkm, and upregulated the protein expression of PFKM. METTL3 silence attenuated HIF-1α-mediated PFKM expression. These findings provide insight into the underlying mechanism of macrophage reprogramming for the treatment of sepsis.

Therapeutic effect of recombinant Echinococcus granulosus antigen B subunit 2 protein on sepsis in a mouse model

BACKGROUND

Sepsis is a potentially fatal systemic inflammatory response syndrome (SIRS) that threatens millions of lives worldwide. Echinococcus granulosus antigen B (EgAgB) is a protein released by the larvae of the tapeworm. This protein has been shown to play an important role in modulating host immune response. In this study we expressed EgAgB as soluble recombinant protein in E. coli (rEgAgB) and explored its protective effect on sepsis.

METHODS

The sepsis model was established by cecal ligation and puncture (CLP) procedure in BALB/c mice. The therapeutic effect of rEgAgB on sepsis was performed by interperitoneally injecting 5 µg rEgAgB in mice with CLP-induced sepsis and observing the 72 h survival rate after onset of sepsis. The proinflammatory cytokines [tumor necrosis factor (TNF)-α, interleukin (IL)-6] and regulatory cytokines [IL-10, transforming growth factor beta (TGF-β)] were measured in sera, and the histopathological change was observed in livers, kidneys, and lungs of septic mice treated with rEgAgB compared with untreated mice. The effect of rEgAgB on the macrophage polarization was performed in vitro by incubating rEgAgB with peritoneal macrophages. The levels of TLR2 and MyD88 were measured in these tissues to determine the involvement of TLR-2/MyD88 in the sepsis-induced inflammatory signaling pathway.

RESULTS

In vivo, we observed that treatment with rEgAgB significantly increased the survival rate of mice with CLP-induced sepsis up to 72 h while all mice without treatment died within the same period. The increased survival was associated with reduced pathological damage in key organs such as liver, lung, and kidneys. It was supported by the reduced proinflammatory cytokine levels and increased regulatory cytokine expression in peripheral blood and key organ tissues. Further study identified that treatment with rEgAgB promoted macrophage polarization from classically activated macrophage (M1) to regulatory M2-like macrophage via inhibiting TLR2/MyD88 signal pathway.

CONCLUSIONS

The therapeutic effects of rEgAgB on mice with sepsis was observed in a mice model that was associated with reduced inflammatory responses and increased regulatory responses, possibly through inducing polarization of macrophages from proinflammatory M1 to regulatory M2 phenotype through inhibiting TLR2/MyD88 inflammatory pathway.

Dehydrocostus Lactone Ameliorates LPS-Induced Acute Lung Injury by Inhibiting PFKFB3-Mediated Glycolysis

Acute lung injury (ALI) is a destructive respiratory disease characterized by alveolar structural destruction and excessive inflammation responses. Aerobic glycolysis of macrophages plays a crucial role in the pathophysiology of ALI. Previous studies have shown that the expression of the key rate-limiting enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) in inflammatory cells is significantly increased, which promotes an increase in the rate of glycolysis in inflammatory cells. However, little is known about the biological functions of PFKFB3 in macrophage inflammation and ALI. In this study, we identified that PFKFB3 is markedly increased in lipopolysaccharide (LPS)-induced ALI mice and macrophages. Knockdown of pfkfb3 attenuated LPS-induced glycolytic flux, decreased the release of pro-inflammatory cytokines, and inactivated NF-κB signaling pathway in macrophages. Subsequently, we found that dehydrocostus lactone (DL), a natural sesquiterpene lactone, significantly decreased both the mRNA and protein levels of PFKFB3. Furthermore, it reduced the release of inflammatory cytokines and inactivated NF-κB pathways in vitro. Accordingly, DL alleviated LPS-induced pulmonary edema and reduced the infiltration of inflammatory cells in mouse lung tissue. In summary, our study reveals the vital role of PFKFB3 in LPS-induced inflammation and discovers a novel molecular mechanism underlying DL's protective effects on ALI.

Immunological alterations in the endothelial barrier: a new predictive and therapeutic paradigm for sepsis

INTRODUCTION

Despite the fact incidence and mortality vary widely among regions, sepsis remains a major cause of morbidity and cost worldwide. The importance of the endothelial barrier in sepsis and infectious diseases is increasingly recognized; however, the underlying pathophysiology of the endothelial barrier in sepsis remains poorly understood.

AREAS COVERED

Here we review the advances in basic and clinical research for relevant papers in PubMed database. We attempt to provide an updated overview of immunological alterations in endothelial dysfunction, discussing the central role of endothelial barrier involved in sepsis to provide new predictive and therapeutic paradigm for sepsis.

EXPERT OPINION

Given its physiological and immunological functions in infectious diseases, the endothelial barrier has been dramatically altered in sepsis, suggesting that endothelial dysfunction may play a critical role in the pathogenesis of sepsis. Although many reliable biomarkers have been investigated to monitor endothelial activation and injury in an attempt to find diagnostic and therapeutic tools, there are no specific therapies to treat sepsis due to its complex pathophysiology. Since sepsis is initiated by both hyperinflammation and immunoparalysis occurring simultaneously, a 'one-treatment-fits-all' strategy for sepsis-induced immune injury and immunoparalysis is bound to fail, and an individualized 'precision medicine' approach is required.

Pathogenic role of PFKFB3 in endothelial inflammatory diseases

The differentiation of vascular endothelial cells and the formation of new blood vessels are inseparable from the energy supply and regulation of metabolism. The budding of blood vessels is a starting point of glycolysis pathway in angiogenesis. Phosphofructokinase-2/fructose 2,6-biophosphatase 3 (PFKFB3), a key rate-limiting enzyme in glycolysis, exhibits strong kinase activity. Inhibition of PFKFB3 can reduce the rate of glycolysis, thereby inhibiting the budding of blood vessels, resulting in inhibition of pathological angiogenesis. In this review, the role of PFKFB3 in the angiogenesis of inflammatory diseases was summarized, and the endothelial inflammatory diseases associated with PFKFB3 were reviewed.

Endothelial dysfunction: Pathophysiology and therapeutic targets for sepsis-induced multiple organ dysfunction syndrome

Sepsis and septic shock are critical medical conditions characterized by a systemic inflammatory response to infection, significantly contributing to global mortality rates. The progression to multiple organ dysfunction syndrome (MODS) represents the most severe complication of sepsis and markedly increases clinical mortality. Central to the pathophysiology of sepsis, endothelial cells play a crucial role in regulating microcirculation and maintaining barrier integrity across various organs and tissues. Recent studies have underscored the pivotal role of endothelial function in the development of sepsis-induced MODS. This review aims to provide a comprehensive overview of the pathophysiology of sepsis-induced MODS, with a specific focus on endothelial dysfunction. It also compiles compelling evidence regarding potential small molecules that could attenuate sepsis and subsequent multi-organ damage by modulating endothelial function. Thus, this review serves as an essential resource for clinical practitioners involved in the diagnosing, managing, and providing intensive care for sepsis and associated multi-organ injuries, emphasizing the importance of targeting endothelial cells to enhance outcomes of the patients.

Pharmacological mechanisms of Ma Xing Shi Gan Decoction in treating influenza virus-induced pneumonia: intestinal microbiota and pulmonary glycolysis

Background

Influenza virus is one of the most common pathogens that cause viral pneumonia. During pneumonia, host immune inflammation regulation involves microbiota in the intestine and glycolysis in the lung tissues. In the clinical guidelines for pneumonia treatment in China, Ma Xing Shi Gan Decoction (MXSG) is a commonly prescribed traditional Chinese medicine formulation with significant efficacy, however, it remains unclear whether its specific mechanism of action is related to the regulation of intestinal microbiota structure and lung tissue glycolysis.

Objective

This study aimed to investigate the mechanism of action of MXSG in an animal model of influenza virus-induced pneumonia. Specifically, we aimed to elucidate how MXSG modulates intestinal microbiota structure and lung tissue glycolysis to exert its therapeutic effects on pneumonia.

Methods

We established a mouse model of influenza virus-induced pneumoni, and treated with MXSG. We observed changes in inflammatory cytokine levels and conducted 16S rRNA gene sequencing to assess the intestinal microbiota structure and function. Additionally, targeted metabolomics was performed to analyze lung tissue glycolytic metabolites, and Western blot and enzyme-linked immunosorbent assays were performed to assess glycolysis-related enzymes, lipopolysaccharides (LPSs), HIF-1a, and macrophage surface markers. Correlation analysis was conducted between the LPS and omics results to elucidate the relationship between intestinal microbiota and lung tissue glycolysis in pneumonia animals under the intervention of Ma Xing Shi Gan Decoction.

Results

MXSG reduced the abundance of Gram-negative bacteria in the intestines, such as Proteobacteria and Helicobacter, leading to reduced LPS content in the serum and lungs. This intervention also suppressed HIF-1a activity and lung tissue glycolysis metabolism, decreased the number of M1-type macrophages, and increased the number of M2-type macrophages, effectively alleviating lung damage caused by influenza virus-induced pneumonia.

Conclusion

MXSG can alleviate glycolysis in lung tissue, suppress M1-type macrophage activation, promote M2-type macrophage activation, and mitigate inflammation in lung tissue. This therapeutic effect appears to be mediated by modulating gut microbiota and reducing endogenous LPS production in the intestines. This study demonstrates the therapeutic effects of MXSG on pneumonia and explores its potential mechanism, thus providing data support for the use of traditional Chinese medicine in the treatment of respiratory infectious diseases.

Early Use of PCSK9 Inhibitors in the Prognosis of Patients with Acute Coronary Syndrome by Protecting Vascular Endothelial Function

INTRODUCTION

Proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) has a protective effect on acute coronary syndrome (ACS). However, most studies have shown that this protective effect is based on a decrease in low-density lipoprotein cholesterol, while other mechanisms remain limited. This study aimed to determine whether PCSK9i can improve the prognosis of ACS patients by protecting endothelial function.

METHODS

A total of 113 ACS patients were enrolled and randomly assigned to PCSK9i group (PCSK9i combined with statins) and control group (statins only). Blood lipids and endothelial function indicators were measured and analyzed 6 weeks before and after treatment. The effect of PCSK9i on the expression and secretion of endothelial function indicators in vascular endothelial cells were studied by cell experiments.

RESULTS

After 6 weeks of treatment, endothelial function indicators such as nitric oxide (NO), thrombomodulin, intercellular cell adhesion molecule-1, endothelin-1, and flow-mediated vasodilation were significantly improved in PCSK9i group compared with control group. Only the changes of NO and von Willebrand factor were associated with blood lipid levels, whereas the changes of other endothelial function indicators were not significantly associated with blood lipid levels. PCSK9i reduced the incidence of major adverse cardiovascular events in patients with ACS compared to those in the control group. In cell experiments, PCSK9i treatment significantly ameliorated LPS induced endothelial injury in HUVECs.

CONCLUSION

PCSK9i can protect vascular endothelial function partly independently of its lipid-lowering effect and ameliorate the prognosis of patients with ACS within 6 weeks. This mechanism may involve heat shock transcription factor 1/heat shock proteins -related signaling pathways. Early use of PCSK9i in patients with ACS should be strongly considered in clinical practice.

PFKFB3-mediated glycolysis in hepatic stellate cells promotes liver regeneration

Hepatic stellate cells (HSCs) perform a significant function in liver regeneration (LR) by becoming active. We propose to investigate if activated HSCs enhance glycolysis via PFKFB3, an essential glycolytic regulator, and whether targeting this pathway could be beneficial for LR. The liver and isolated HSCs of mice subjected to 2/3 partial hepatectomy (PHx) exhibited a significant rise in PFKFB3 expression, as indicated by quantitative RT-PCR analyses and Western blotting. Also, the primary HSCs of mice subjected to PHx have a significant elevation of the glycolysis level. Knocking down PFKFB3 significantly diminished the enhancement of glycolysis by PDGF in human LX2 cells. The hepatocyte proliferation in mice treated with PHx was almost completely prevented when the PFKFB3 inhibitor 3PO was administered, emerging that PFKFB3 is essential in LR. Furthermore, there was a decline in mRNA expression of immediate early genes and proinflammatory cytokines. In terms of mechanism, both the p38 MAP kinase and ERK1/2 phosphorylation in LO2 cells and LO2 proliferation were significantly reduced by the conditioned medium (CM) obtained from LX2 cells with either PFKFB3 knockdown or inhibition. Compared to the control group, isolated hepatocytes from 3PO-treated mice showed decreased p38 MAP kinase and ERK1/2 phosphorylation and proliferation. Thus, LR after PHx involves the activation of PFKFB3 in HSCs, which enhances glycolysis and promotes lactate production, thereby facilitating hepatocyte proliferation via the p38/ERK MAPK signaling pathway.

Mechanisms of pulmonary endothelial barrier dysfunction in acute lung injury and acute respiratory distress syndrome

Endothelial cells (ECs) form a semi-permeable barrier between the interior space of blood vessels and the underlying tissues. Pulmonary endothelial barrier integrity is maintained through coordinated cellular processes involving receptors, signaling molecules, junctional complexes, and protein-regulated cytoskeletal reorganization. In acute lung injury (ALI) or its more severe form acute respiratory distress syndrome (ARDS), the loss of endothelial barrier integrity secondary to endothelial dysfunction caused by severe pulmonary inflammation and/or infection leads to pulmonary edema and hypoxemia. Pro-inflammatory agonists such as histamine, thrombin, bradykinin, interleukin 1β, tumor necrosis factor α, vascular endothelial growth factor, angiopoietin-2, and platelet-activating factor, as well as bacterial toxins and reactive oxygen species, cause dynamic changes in cytoskeletal structure, adherens junction disorganization, and detachment of vascular endothelial cadherin (VE-cadherin) from the actin cytoskeleton, leading to an increase in endothelial permeability. Endothelial interactions with leukocytes, platelets, and coagulation enhance the inflammatory response. Moreover, inflammatory infiltration and the associated generation of pro-inflammatory cytokines during infection cause EC death, resulting in further compromise of the structural integrity of lung endothelial barrier. Despite the use of potent antibiotics and aggressive intensive care support, the mortality of ALI is still high, because the mechanisms of pulmonary EC barrier disruption are not fully understood. In this review, we summarized recent advances in the studies of endothelial cytoskeletal reorganization, inter-endothelial junctions, endothelial inflammation, EC death, and endothelial repair in ALI and ARDS, intending to shed some light on the potential diagnostic and therapeutic targets in the clinical management of the disease.

Immunotherapy in the context of sepsis-induced immunological dysregulation

Sepsis is a clinical syndrome caused by uncontrollable immune dysregulation triggered by pathogen infection, characterized by high incidence, mortality rates, and disease burden. Current treatments primarily focus on symptomatic relief, lacking specific therapeutic interventions. The core mechanism of sepsis is believed to be an imbalance in the host's immune response, characterized by early excessive inflammation followed by late immune suppression, triggered by pathogen invasion. This suggests that we can develop immunotherapeutic treatment strategies by targeting and modulating the components and immunological functions of the host's innate and adaptive immune systems. Therefore, this paper reviews the mechanisms of immune dysregulation in sepsis and, based on this foundation, discusses the current state of immunotherapy applications in sepsis animal models and clinical trials.

Emerging roles of lactate in acute and chronic inflammation

Traditionally, lactate has been considered a 'waste product' of cellular metabolism. Recent findings have shown that lactate is a substance that plays an indispensable role in various physiological cellular functions and contributes to energy metabolism and signal transduction during immune and inflammatory responses. The discovery of lactylation further revealed the role of lactate in regulating inflammatory processes. In this review, we comprehensively summarize the paradoxical characteristics of lactate metabolism in the inflammatory microenvironment and highlight the pivotal roles of lactate homeostasis, the lactate shuttle, and lactylation ('lactate clock') in acute and chronic inflammatory responses from a molecular perspective. We especially focused on lactate and lactate receptors with either proinflammatory or anti-inflammatory effects on complex molecular biological signalling pathways and investigated the dynamic changes in inflammatory immune cells in the lactate-related inflammatory microenvironment. Moreover, we reviewed progress on the use of lactate as a therapeutic target for regulating the inflammatory response, which may provide a new perspective for treating inflammation-related diseases.

Endothelial cell dynamics in sepsis-induced acute lung injury and acute respiratory distress syndrome: pathogenesis and therapeutic implications

Sepsis, a prevalent critical condition in clinics, continues to be the leading cause of death from infections and a global healthcare issue. Among the organs susceptible to the harmful effects of sepsis, the lungs are notably the most frequently affected. Consequently, patients with sepsis are predisposed to developing acute lung injury (ALI), and in severe cases, acute respiratory distress syndrome (ARDS). Nevertheless, the precise mechanisms associated with the onset of ALI/ARDS remain elusive. In recent years, there has been a growing emphasis on the role of endothelial cells (ECs), a cell type integral to lung barrier function, and their interactions with various stromal cells in sepsis-induced ALI/ARDS. In this comprehensive review, we summarize the involvement of endothelial cells and their intricate interplay with immune cells and stromal cells, including pulmonary epithelial cells and fibroblasts, in the pathogenesis of sepsis-induced ALI/ARDS, with particular emphasis placed on discussing the several pivotal pathways implicated in this process. Furthermore, we discuss the potential therapeutic interventions for modulating the functions of endothelial cells, their interactions with immune cells and stromal cells, and relevant pathways associated with ALI/ARDS to present a potential therapeutic strategy for managing sepsis and sepsis-induced ALI/ARDS.

QiShenYiQi pills preserve endothelial barrier integrity to mitigate sepsis-induced acute lung injury by inhibiting ferroptosis

ETHNOPHARMACOLOGICAL RELEVANCE

The QiShengYiQi pill (QSYQ) is a traditional Chinese medicinal formulation. The effectiveness and safety of QSYQ in treating respiratory system disorders have been confirmed. Its pharmacological actions include anti-inflammation, antioxidative stress, and improving energy metabolism. However, the mechanism of QSYQ in treating sepsis-induced acute lung injury (si-ALI) remains unclear.

AIM OF THE STUDY

Si-ALI presents a clinical challenge with high incidence and mortality rates. This study aims to confirm the efficacy of QSYQ in si-ALI and to explore the potential mechanisms, providing a scientific foundation for its application and insights for optimizing treatment strategies and identifying potential active components.

MATERIALS AND METHODS

The impact of QSYQ on si-ALI was evaluated using the cecal ligation and puncture (CLP) experimental sepsis animal model. The effects of QSYQ on endothelial cells were observed through coculturing with LPS-stimulated macrophage-conditioned medium. Inflammatory cytokine levels, HE staining, Evans blue staining, lung wet/dry ratio, and cell count and protein content in bronchoalveolar lavage fluid were used to assess the degree of lung injury. Network pharmacology was utilized to investigate the potential mechanisms of QSYQ in treating si-ALI. Western blot and immunofluorescence analyses were used to evaluate barrier integrity and validate mechanistically relevant proteins.

RESULTS

QSYQ reduced the inflammation and alleviated pulmonary vascular barrier damage in CLP mice (all P < 0.05). A total of 127 potential targets through which QSYQ regulates si-ALI were identified, predominantly enriched in the RAGE pathway. The results of protein-protein interaction analysis suggest that COX2, a well-established critical marker of ferroptosis, is among the key targets. In vitro and in vivo studies demonstrated that QSYQ mitigated ferroptosis and vascular barrier damage in sepsis (all P < 0.05), accompanied by a reduction in oxidative stress and the inhibition of the COX2 and RAGE (all P < 0.05).

CONCLUSIONS

This study demonstrated that QSYQ maintains pulmonary vascular barrier integrity by inhibiting ferroptosis in CLP mice. These findings partially elucidate the mechanism of QSYQ in si-ALI and further clarify the active components of QSYQ, thereby providing a scientific theoretical basis for treating si-ALI with QSYQ.

Single-Cell Transcriptomics Reveals the Ameliorative Effect of Oridonin on Septic Liver Injury

Sepsis is a life-threatening syndrome leading to hemodynamic instability and potential organ dysfunction. Oridonin, commonly used in Traditional Chinese Medicine (TCM), exhibits significant anti-inflammation activity. To explore the protective mechanisms of oridonin against the pathophysiological changes, the authors conducted single-cell transcriptome (scRNA-seq) analysis on septic liver models induced by cecal ligation and puncture (CLP). They obtained a total of 63,486 cells, distributed across 11 major cell clusters, and concentrated their analysis on four specific clusters (hepatocytes/Heps, macrophages, endothelial/Endos and T/NK) based on their changes in proportion during sepsis and under oridonin treatment. Firstly, biological changes in Hep, which are related to metabolic dysregulation and pro-inflammatory signaling, are observed during sepsis. Secondly, they uncovered the dynamic profiles of macrophage's phenotype, indicating that a substantial number of macrophages exhibited a M1-skewed phenotype associated with pro-inflammatory characteristics in septic model. Thirdly, they detected an upregulation of both inflammatory cytokines and transcriptomic factor Nfkb1 expression within Endo, along with slight capillarization during sepsis. Moreover, excessive accumulation of cytotoxic NK led to an immune imbalance. Though, oridonin ameliorated inflammatory-related responses and improved the liver dysfunction in septic mice. This study provides fundamental evidence of the protective effects of oridonin against sepsis-induced cytokine storm.

Ferroptosis mediates airway epithelial E-cadherin dysfunction in LPS-induced acute lung injury

BACKGROUND

Loss of E-cadherin in the airway epithelial cells is a critical contributor to the development of ALI/ARDS. Yet the underlying mechanisms are largely unknown. Increasing evidences have revealed the significance of ferroptosis in the pathophysiological process of ALI/ARDS. The aim of this study was to investigate the role of ferroptosis in dysregulation of airway epithelial E-cadherin in ALI/ARDS.

METHODS

BALB/c mice were subjected to intratracheal instillation of lipopolysaccharide (LPS) to establish an ALI model. Two inhibitors of ferroptosis, liproxstatin-1 (Lip-1, at the dose of 10 mg/kg and 30 mg/kg) and ferrostatin-1 (Fer-1, at the dose of 1 mg/kg and 5 mg/kg), were respectively given to the mice through intraperitoneal injection after LPS challenge. The expression of ferroptotic markers, full-length E-cadherin and soluble E-cadherin (sE-cadherin) were both detected.

RESULTS

LPS exposure dramatically down-regulated pulmonary expression of E-cadherin in mice, with profound loss of membrane E-cadherin in the airway epithelial cells and increased secretion of sE-cadherin in the airway lumen. At the same time, we found that the mitochondrial of airway epithelial cells in LPS-exposed mice exhibited significant morphological alterations that are hallmark features of ferroptosis, with smaller volume and increased membrane density. Other makers of ferroptosis were also detected, including increased cytoplasmic levels of iron and lipid peroxidates (MDA), as well as decreased GPX4 expression. 30 mg/kg of Lip-1 not only showed potent protective effects against the LPS-induced injury, inflammation, edema of the lung in those mice, but also rescued airway epithelial E-cadherin expression and decreased the release of sE-cadherin through inhibiting ferroptosis. While no noticeable changes induced by LPS were observed in mice treated with Lip-1 at 10 mg/kg nor Fer-1 at 1 mg/kg or 5 mg/kg.

CONCLUSIONS

Taken together, these data demonstrated that ferroptosis mediates airway epithelial E-cadherin dysfunction in LPS-induced ALI.

Possible pharmacological targets and mechanisms of sivelestat in protecting acute lung injury

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a life-threatening syndrome induced by various diseases, including COVID-19. In the progression of ALI/ARDS, activated neutrophils play a central role by releasing various inflammatory mediators, including elastase. Sivelestat is a selective and competitive inhibitor of neutrophil elastase. Although its protective effects on attenuating ALI/ARDS have been confirmed in several models of lung injury, clinical trials have presented inconsistent results on its therapeutic efficacy. Therefore, in this report, we used a network pharmacology approach coupled with animal experimental validation to unravel the concrete therapeutic targets and biological mechanisms of sivelestat in treating ALI/ARDS. In bioinformatic analyses, we found 118 targets of sivelestat against ALI/ARDS, and identified six hub genes essential for sivelestat treatment of ALI/ARDS, namely ERBB2, GRB2, PTK2, PTPN11, ESR1, and CCND1. We also found that sivelestat targeted several genes expressed in human lung microvascular endothelial cells after lipopolysaccharide (LPS) treatment at 4 h (ICAM-1, PTGS2, RND1, BCL2A1, TNF, CA2, and ADORA2A), 8 h (ICAM-1, PTGS2, RND1, BCL2A1, MMP1, BDKRB1 and SLC40A1), and 24 h (ICAM-1). Further animal experiments showed that sivelestat was able to attenuate LPS-induced ALI by inhibiting the overexpression of ICAM-1, VCAM-1, and PTGS2 and increasing the phosphorylation of PTK2. Taken together, the bioinformatic findings and experimentative data indicate that the therapeutic effects of sivelestat against ALI/ARDS mainly focus on the early stage of ALI/ARDS by pharmacological modulation of inflammatory reaction, vascular endothelial injury, and cell apoptosis-related molecules.

FGF18 alleviates sepsis-induced acute lung injury by inhibiting the NF-κB pathway

BACKGROUND

Acute lung injury (ALI) is a devastating clinical disorder with a high mortality rate, and there is an urgent need for more effective therapies. Fibroblast growth factor 18 (FGF18) has potent anti-inflammatory properties and therefore has become a focus of research for the treatment of lung injury. However, the precise role of FGF18 in the pathological process of ALI and the underlying mechanisms have not been fully elucidated.

METHODS

A mouse model of ALI and human umbilical vein endothelial cells (HUVEC) stimulated with lipopolysaccharide (LPS) was established in vivo and in vitro. AAV-FGF18 and FGF18 proteins were used in C57BL/6J mice and HUVEC, respectively. Vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and p65 protein levels were determined by western blotting or immunofluorescent staining. Afterward, related inhibitors were used to explore the potential mechanism by which FGF18 relieves inflammation.

RESULTS

In this study, we found that FGF18 was significantly upregulated in LPS-induced ALI mouse lung tissues and LPS-stimulated HUVECs. Furthermore, our studies demonstrated that overexpressing FGF18 in the lung or HUVEC could significantly alleviate LPS-induced lung injury and inhibit vascular leakage.

CONCLUSIONS

Mechanically, FGF18 treatment dramatically inhibited the NF-κB signaling pathway both in vivo and in vitro. In conclusion, these results indicate that FGF18 attenuates lung injury, at least partially, via the NF-κB signaling pathway and therefore may be a potential therapeutic target for ALI.

ACE2 improves endothelial cell function and reduces acute lung injury by downregulating FAK expression

Endothelial cell (EC) barrier dysfunction and increased adhesion of immune inflammatory cells to ECs crucially contribute to acute lung injury (ALI). Angiotensin-converting enzyme 2 (ACE2) is an essential regulator of the renin-angiotensin system (RAS) and exerts characteristic vasodilatory and anti-inflammatory effects. SARS-COV-2 infects the lungs by binding to ACE2, which can lead to dysregulation of ACE2 expression, further leading to ALI with predominantly vascular inflammation and eventually to more severe acute respiratory distress syndrome (ARDS). Therefore, restoration of ACE2 expression represents a valuable therapeutic approach for SARS-COV-2-related ALI/ARDS. In this study, we used polyinosinic-polycytidylic acid (Poly(I:C)), a double-stranded RNA analog, to construct a mouse ALI model that mimics virus infection. After Poly(I:C) exposure, ACE2 was downregulated in mouse lung tissues and in cultured ECs. Treatment with DIZE, an ACE2-activating compound, upregulated ACE2 expression and relieved ALI in mice. DIZE also improved barrier function and reduced the number of THP-1 monocytes adhering to cultured ECs. Focal adhesion kinase (FAK) and phosphorylated FAK (p-FAK) levels were increased in lung tissues of ALI mice as well as in Poly(I:C)-treated ECs in vitro. Both DIZE and the FAK inhibitor PF562271 decreased FAK/p-FAK expression in both ALI models, attenuating ALI severity in vivo and increasing barrier function and reducing monocyte adhesion in cultured ECs. Furthermore, in vivo experiments using ANG 1-7 and the MAS inhibitor A779 corroborated that DIZE-mediated ACE2 activation stimulated the activity of the ANG 1-7/MAS axis, which inhibited FAK/p-FAK expression in the mouse lung. These findings provide further evidence that activation of ACE2 in ECs may be a valuable therapeutic strategy for ALI.

PFKFB3 in neovascular eye disease: unraveling mechanisms and exploring therapeutic strategies

BACKGROUND

Neovascular eye disease is characterized by pathological neovascularization, with clinical manifestations such as intraocular exudation, bleeding, and scar formation, ultimately leading to blindness in millions of individuals worldwide. Pathologic ocular angiogenesis often occurs in common fundus diseases including proliferative diabetic retinopathy (PDR), age-related macular degeneration (AMD), and retinopathy of prematurity (ROP). Anti-vascular endothelial growth factor (VEGF) targets the core pathology of ocular angiogenesis.

MAIN BODY

In recent years, therapies targeting metabolism to prevent angiogenesis have also rapidly developed, offering assistance to patients with a poor prognosis while receiving anti-VEGF therapy and reducing the side effects associated with long-term VEGF usage. Phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), a key enzyme in targeted metabolism, has been shown to have great potential, with antiangiogenic effects and multiple protective effects in the treatment of neovascular eye disease. In this review, we summarize the mechanisms of common types of neovascular eye diseases; discuss the protective effect and potential mechanism of targeting PFKFB3, including the related inhibitors of PFKFB3; and look forward to the future exploration directions and therapeutic prospects of PFKFB3 in neovascular eye disease.

CONCLUSION

Neovascular eye disease, the most common and severely debilitating retinal disease, is largely incurable, necessitating the exploration of new treatment methods. PFKFB3 has been shown to possess various potential protective mechanisms in treating neovascular eye disease. With the development of several drugs targeting PFKFB3 and their gradual entry into clinical research, targeting PFKFB3-mediated glycolysis has emerged as a promising therapeutic approach for the future of neovascular eye disease.

SIRT6 Protects Against Lipopolysaccharide-Induced Inflammation in Human Pulmonary Lung Microvascular Endothelial Cells

Inflammatory response in the pulmonary endothelium drives the pathogenesis of acute lung injury and sepsis. Sirtuin 6 (SIRT6), a member of class III NAD+-dependent deacetylases belonging to the sirtuin family, regulates senescence, metabolism, and inflammation and extends lifespan in mice and model organisms. However, the role of SIRT6 in pulmonary endothelial inflammation is unknown. Thus, we hypothesized that SIRT6 suppresses inflammatory response in human lung microvascular cells (HLMEC) and ensues monocyte adhesion to endothelial cells. Primary HLMECs were treated with control or SIRT6 adenovirus or SIRT6 agonist, with or without lipopolysaccharide (LPS) treatment. We observed that treatment with LPS did not affect the protein expression of SIRT6 in HLMECs. However, adenovirus-mediated SIRT6 overexpression attenuated LPS-induced VCAM1 gene and protein expression, followed by decreased monocyte adhesion to endothelial cells. Similarly, activation of SIRT6 by a recently reported SIRT6 activator UBCS039, but not the regioisomer negative control compound UBCS060, ameliorated LPS-induced VCAM1 mRNA and protein expression as well as monocyte adhesion. Moreover, luciferase assay revealed that SIRT6 adenovirus decreased the activity of NF-κB, the master regulator of vascular inflammation. Taken together, these results indicate that molecular and pharmacological activation of SIRT6 protects against lung microvascular inflammation via suppressing NF-κB activation, implicating the therapeutic potential of the SIRT6 activators for lung disorders associated with microvascular inflammation.

Type I Interferons induce endothelial destabilization in Systemic Lupus Erythematosus in a Tie2-dependent manner

Endothelial cell (EC) dysfunction is a hallmark of Systemic Lupus Erythematosus (SLE) and Tie2 is a receptor essential for vascular stability. Inflammatory processes promote inhibition of Tie2 homeostatic activation, driving vascular dysfunction. In this work we determined whether type I Interferons (IFN) induce Tie2 signalling-mediated endothelial dysfunction in patients with SLE. Serum levels of Angiopoietin (Ang)-1, Ang-2 and soluble (s)Tie1 in patients with SLE and healthy controls were measured by ELISA. Monocytes from patients with SLE and Human Umbilical Vein EC (HUVEC) were stimulated with IFN-α, IFN-β (1000 I.U.) or SLE serum (20%). mRNA and protein expression, phosphorylation and translocation were determined by quantitative PCR, ELISA, Western Blot, flow cytometry and confocal microscopy. Viability and angiogenic capacity were determined by calcein and tube formation assays. We found that sTie1 and Ang-2 serum levels were increased and Ang-1 decreased in patients with SLE and were associated with clinical characteristics. Type I IFN significantly decreased Ang-1 and increased Ang-2 in monocytes from patients with SLE. Type I IFN increased sTie1 and Ang-2 secretion and reduced Tie2 activation in HUVEC. Functionally, type I IFN significantly reduced EC viability and impaired angiogenesis in a Tie2 signalling-dependent manner. Finally, SLE serum increased Ang-2 and sTie1 secretion and significantly decreased tube formation. Importantly, Tie1 and IFNAR1 knockdown reversed these effects in tube formation. Overall, type I IFN play an important role in the stability of EC by inhibiting Tie2 signalling, suggesting that these processes may be implicated in the cardiovascular events observed in patients with SLE.

Therapeutic effect of Echinococcus granulosus cyst fluid on bacterial sepsis in mice

BACKGROUND

The primary pathophysiological process of sepsis is to stimulate a massive release of inflammatory mediators to trigger systemic inflammatory response syndrome (SIRS), the major cause of multi-organ dysfunction and death. Like other helminths, Echinococcus granulosus induces host immunomodulation. We sought to determine whether E. granulosus cyst fluid (EgCF) displays a therapeutic effect on sepsis-induced inflammation and tissue damage in a mouse model.

METHODS

The anti-inflammatory effects of EgCF were determined by in vitro culture with bone marrow-derived macrophages (BMDMs) and in vivo treatment of BALB/C mice with cecal ligation and puncture (CLP)-induced sepsis. The macrophage phenotypes were determined by flow cytometry, and the levels of cytokines in cell supernatants or in sera of mice were measured (ELISA). The therapeutic effect of EgCF on sepsis was evaluated by observing the survival rates of mice for 72 h after CLP, and the pathological injury to the liver, kidney, and lung was measured under a microscope. The expression of TLR-2/MyD88 in tissues was measured by western blot to determine whether TLR-2/MyD88 is involved in the sepsis-induced inflammatory signaling pathway.

RESULTS

In vitro culture with BMDMs showed that EgCF promoted macrophage polarization to M2 type and inhibited lipopolysaccharide (LPS)-induced M1 macrophages. EgCF treatment provided significant therapeutic effects on CLP-induced sepsis in mice, with increased survival rates and alleviation of tissue injury. The EgCF conferred therapeutic efficacy was associated with upregulated anti-inflammatory cytokines (IL-10 and TGF-β) and reduced pro-inflammatory cytokines (TNF-α and INF-γ). Treatment with EgCF induced Arg-1-expressed M2, and inhibited iNOS-expressed M1 macrophages. The expression of TLR-2 and MyD88 in EgCF-treated mice was reduced.

CONCLUSIONS

The results demonstrated that EgCF confers a therapeutic effect on sepsis by inhibiting the production of pro-inflammatory cytokines and inducing regulatory cytokines. The anti-inflammatory effect of EgCF is carried out possibly through inducing macrophage polarization from pro-inflammatory M1 to regulatory M2 phenotype to reduce excessive inflammation of sepsis and subsequent multi-organ damage. The role of EgCF in regulating macrophage polarization may be achieved by inhibiting the TLR2/MyD88 signaling pathway.

Crosstalk between neutrophil extracellular traps and immune regulation: insights into pathobiology and therapeutic implications of transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-associated death, occurring during or within 6 hours after transfusion. Reports indicate that TRALI can be categorized as having or lacking acute respiratory distress syndrome (ARDS) risk factors. There are two types of TRALI in terms of its pathogenesis: antibody-mediated and non-antibody-mediated. The key initiation steps involve the priming and activation of neutrophils, with neutrophil extracellular traps (NETs) being established as effector molecules formed by activated neutrophils in response to various stimuli. These NETs contribute to the production and release of reactive oxygen species (ROS) and participate in the destruction of pulmonary vascular endothelial cells. The significant role of NETs in TRALI is well recognized, offering a potential pathway for TRALI treatment. Moreover, platelets, macrophages, endothelial cells, and complements have been identified as promoters of NET formation. Concurrently, studies have demonstrated that the storage of platelets and concentrated red blood cells (RBC) can induce TRALI through bioactive lipids. In this article, recent clinical and pre-clinical studies on the pathophysiology and pathogenesis of TRALI are reviewed to further illuminate the mechanism through which NETs induce TRALI. This review aims to propose new therapeutic strategies for TRALI, with the hope of effectively improving its poor prognosis.

Hyperglycolysis in endothelial cells drives endothelial injury and microvascular alterations in peritoneal dialysis

BACKGROUND

Endothelial cell (EC) dysfunction leading to microvascular alterations is a hallmark of technique failure in peritoneal dialysis (PD). However, the mechanisms underlying EC dysfunction in PD are poorly defined.

METHODS

We combined RNA sequencing with metabolite set analysis to characterize the metabolic profile of peritoneal ECs from a mouse model of PD. This was combined with EC-selective blockade of glycolysis by genetic or pharmacological inhibition of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) in vivo and in vitro. We also investigated the association between peritoneal EC glycolysis and microvascular alterations in human peritoneal samples from patients with end-stage kidney disease (ESKD).

RESULTS

In a mouse model of PD, peritoneal ECs had a hyperglycolytic metabolism that shunts intermediates into nucleotide synthesis. Hyperglycolytic mouse peritoneal ECs displayed a unique active phenotype with increased proliferation, permeability and inflammation. The active phenotype of mouse peritoneal ECs can be recapitulated in human umbilical venous ECs and primary human peritoneal ECs by vascular endothelial growth factor that was released from high glucose-treated mesothelial cells. Importantly, reduction of peritoneal EC glycolysis, via endothelial deficiency of the glycolytic activator PFKFB3, inhibited PD fluid-induced increases in peritoneal capillary density, vascular permeability and monocyte extravasation, thereby protecting the peritoneum from the development of structural and functional damages. Mechanistically, endothelial PFKFB3 deficiency induced the protective effects in part by inhibiting cell proliferation, VE-cadherin endocytosis and monocyte-adhesion molecule expression. Pharmacological PFKFB3 blockade induced a similar therapeutic benefit in this PD model. Human peritoneal tissue from patients with ESKD also demonstrated evidence of increased EC PFKFB3 expression associated with microvascular alterations and peritoneal dysfunction.

CONCLUSIONS

These findings reveal a critical role of glycolysis in ECs in mediating the deterioration of peritoneal function and suggest that strategies targeting glycolysis in peritoneal ECs may be of therapeutic benefit for patients undergoing PD.

Lactate produced by alveolar type II cells suppresses inflammatory alveolar macrophages in acute lung injury

Alveolar inflammation is a hallmark of acute lung injury (ALI), and its clinical correlate is acute respiratory distress syndrome-and it is as a result of interactions between alveolar type II cells (ATII) and alveolar macrophages (AM). In the setting of acute injury, the microenvironment of the intra-alveolar space is determined in part by metabolites and cytokines and is known to shape the AM phenotype. In response to ALI, increased glycolysis is observed in AT II cells, mediated by the transcription factor hypoxia-inducible factor (HIF) 1α, which has been shown to decrease inflammation. We hypothesized that in acute lung injury, lactate, the end product of glycolysis, produced by ATII cells shifts AMs toward an anti-inflammatory phenotype, thus mitigating ALI. We found that local intratracheal delivery of lactate improved ALI in two different mouse models. Lactate shifted cytokine expression of murine AMs toward increased IL-10, while decreasing IL-1 and IL-6 expression. Mice with ATII-specific deletion of Hif1a and mice treated with an inhibitor of lactate dehydrogenase displayed exacerbated ALI and increased inflammation with decreased levels of lactate in the bronchoalveolar lavage fluid; however, all those parameters improved with intratracheal lactate. When exposed to LPS (to recapitulate an inflammatory stimulus as it occurs in ALI), human primary AMs co-cultured with alveolar epithelial cells had reduced inflammatory responses. Taken together, these studies reveal an innate protective pathway, in which lactate produced by ATII cells shifts AMs toward an anti-inflammatory phenotype and dampens excessive inflammation in ALI.

Macrophage LMO7 deficiency facilitates inflammatory injury via metabolic-epigenetic reprogramming

Inflammatory bowel disease (IBD) is a formidable disease due to its complex pathogenesis. Macrophages, as a major immune cell population in IBD, are crucial for gut homeostasis. However, it is still unveiled how macrophages modulate IBD. Here, we found that LIM domain only 7 (LMO7) was downregulated in pro-inflammatory macrophages, and that LMO7 directly degraded 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) through K48-mediated ubiquitination in macrophages. As an enzyme that regulates glycolysis, PFKFB3 degradation led to the glycolytic process inhibition in macrophages, which in turn inhibited macrophage activation and ultimately attenuated murine colitis. Moreover, we demonstrated that PFKFB3 was required for histone demethylase Jumonji domain-containing protein 3 (JMJD3) expression, thereby inhibiting the protein level of trimethylation of histone H3 on lysine 27 (H3K27me3). Overall, our results indicated the LMO7/PFKFB3/JMJD3 axis is essential for modulating macrophage function and IBD pathogenesis. Targeting LMO7 or macrophage metabolism could potentially be an effective strategy for treating inflammatory diseases.

Organotypic heterogeneity in microvascular endothelial cell responses in sepsis-a molecular treasure trove and pharmacological Gordian knot

In the last decades, it has become evident that endothelial cells (ECs) in the microvasculature play an important role in the pathophysiology of sepsis-associated multiple organ dysfunction syndrome (MODS). Studies on how ECs orchestrate leukocyte recruitment, control microvascular integrity and permeability, and regulate the haemostatic balance have provided a wealth of knowledge and potential molecular targets that could be considered for pharmacological intervention in sepsis. Yet, this information has not been translated into effective treatments. As MODS affects specific vascular beds, (organotypic) endothelial heterogeneity may be an important contributing factor to this lack of success. On the other hand, given the involvement of ECs in sepsis, this heterogeneity could also be leveraged for therapeutic gain to target specific sites of the vasculature given its full accessibility to drugs. In this review, we describe current knowledge that defines heterogeneity of organ-specific microvascular ECs at the molecular level and elaborate on studies that have reported EC responses across organ systems in sepsis patients and animal models of sepsis. We discuss hypothesis-driven, single-molecule studies that have formed the basis of our understanding of endothelial cell engagement in sepsis pathophysiology, and include recent studies employing high-throughput technologies. The latter deliver comprehensive data sets to describe molecular signatures for organotypic ECs that could lead to new hypotheses and form the foundation for rational pharmacological intervention and biomarker panel development. Particularly results from single cell RNA sequencing and spatial transcriptomics studies are eagerly awaited as they are expected to unveil the full spatiotemporal signature of EC responses to sepsis. With increasing awareness of the existence of distinct sepsis subphenotypes, and the need to develop new drug regimen and companion diagnostics, a better understanding of the molecular pathways exploited by ECs in sepsis pathophysiology will be a cornerstone to halt the detrimental processes that lead to MODS.