Irf7 regulates the expression of Srg3 and ferroptosis axis aggravated sepsis-induced acute lung injury

Therapeutic potential of ADSC-derived exosomes in acute lung injury by regulating macrophage polarization through IRF7/NLRP3 signaling

Alveolar macrophages (AMs) play a critical role in regulating pulmonary immunity and inflammation. Acute lung injury (ALI), frequently initiated by sepsis-induced systemic inflammation and cytokine storms, leads to heightened lung permeability and respiratory failure. Adipose-derived stem cell exosomes (ADSC-Exos) have shown promise as therapeutic agents due to their immunomodulatory properties. This study assesses the effectiveness of ADSC-Exos in mitigating ALI by modulating macrophage (mø) polarization and suppressing pyroptosis. In vivo, an LPS-induced ALI mouse model demonstrated that ADSC-Exos attenuated lung tissue inflammation and damage, as verified by histological staining, ELISA, and immunofluorescence. In vitro, LPS-stimulated MH-S cells treated with ADSC-Exos showed a decrease in M1 (iNOS, CD86) and an increase in M2 (CD206, Arg-1) markers, as evidenced by Western blotting (WB) and flow cytometry. Mechanistically, RNA sequencing pinpointed IRF7 as a key upstream regulator of pyroptosis. ADSC-Exos inhibited the NLRP3 inflammasome and pyroptosis, fostering a shift from pro-inflammatory M1 to anti-inflammatory M2 mø phenotypes. Overexpression of IRF7 negated these effects, undermining the protective role of ADSC-Exos. Notably, inhibition of exosome secretion with GW4869 nullified these immunomodulatory effects, underscoring the vital role of ADSC-Exos. This study underscores the therapeutic potential of ADSC-Exos in restoring alveolar mø homeostasis, modulating immune responses, and alleviating lung inflammatory injury in ALI. These findings suggest ADSC-Exos as a feasible strategy for treating sepsis-induced pulmonary complications.

Anti-inflammatory properties of Pleione bulbocodioides extract through STING/ NF-κB pathway inhibition

The members of Pleione (Orchidaceae) are popular worldwide for their ornamental appeal and medicinal properties. Pleione bulbocodioides, a CITES Appendix II-listed species, has been traditionally used in dermatological therapies but remains pharmacologically understudied. In this study, the in vitro anti-inflammatory effects of extracts from artificially cultivated P. bulbocodioides were investigated. We found the P. bulbocodioides extract (PE) significantly suppressed TNF-α/IFN-γ-induced expression of IL-6, IL-1β, CCL5, CCL8, CXCL8, CXCL3, and TMEM173 (STING) genes in both HaCaT cells and NHEKs. Transcriptomic analysis and Western blotting confirmed the inhibitory effects on STING/NF-κB signaling pathway of PE. And phytochemical characterization identified militarine and batatasin III as principal bioactive constituents responsible for STING/NF-κB pathway inhibition by PE. PE also demonstrated comparable anti-inflammatory efficacy in LPS-induced RAW 264.7 macrophages and SLS-irritated 3D reconstructed human epidermis. Thus, these findings indicate the potential of PE as a natural anti-inflammatory therapeutic or skincare ingredient for dermatological applications.

Shexiang Baoxin Pill alleviates atherosclerosis by inhibiting macrophage-mediated inflammation via suppressing KMT5A mediated Irf7 transcription

ETHNOPHARMACOLOGICAL RELEVANCE

Shexiang Baoxin Pill (SBP) is a traditional compound formulation composed of seven Chinese medicinal ingredients. Although SBP has shown promising clinical outcomes in the treatment of cardiovascular diseases, its role and underlying mechanisms in alleviating atherosclerosis remain insufficiently studied.

AIM OF THE STUDY

This study aims to investigate the effects and mechanisms of SBP in epigenetic modulating macrophage inflammatory responses to mitigate atherosclerosis.

MATERIALS AND METHODS

ApoE-/- mice were treated with high fat diet (HFD) following varying concentrations of SBP. Oil Red O staining, hematoxylin-eosin (HE) staining, and ELISA were used to assess the anti-atherosclerotic and anti-inflammatory efficiency of SBP. Subsequently, RNA sequencing (RNA-seq), RT-PCR, Western blot (WB), immunofluorescence (IF) and chromatin immunoprecipitation (ChIP) were employed in bone marrow derived macrophages (BMDMs) to elucidate the epigenetic mechanisms of SBP in alleviating macrophage inflammatory responses. Lysine methyltransferase 5A (KMT5A) was overexpressed in vivo and in vitro for further validation.

RESULTS

SBP significantly attenuated atherosclerosis in HFD treated ApoE-/- mice by decreasing plaque areas, serum inflammation levels and macrophages infiltration in the aortic root and plaques. SBP treatment reduced BMDMs inflammatory responses following oxidized low-density lipoprotein (oxLDL) treatment. Mechanistically, SBP inhibited interferon regulatory factor 7 (IRF7) expression by reducing KMT5A-mediated mono-methylation of histone H4 lysine 20 (H4K20), thus decreasing the secretion of multiple pro-inflammatory cytokines, including interferon (IFN)-α, IFN-β, TNF-α. Overexpression of KMT5A abolished the anti-atherosclerotic and anti-inflammatory effects of SBP, further confirming that KMT5A/H4K20me/IRF7 axis is a key target for SBP exerting therapeutic effect.

CONCLUSION

SBP exerts anti-atherosclerotic effects by inhibiting macrophage inflammatory responses through downregulation of the H4K20 methylase KMT5A, thereby suppressing the transcription of Irf7. Our findings provide a novel epigenetic mechanism by which SBP alleviates atherosclerosis.

Wuwei Shaji powder alleviates OVA-induced allergic asthma by protecting bronchial epithelial cells from ferroptosis via the S-sulfhydration of Keap1

ETHNOPHARMACOLOGICAL RELEVANCE

Asthma is a chronic inflammatory airway disease. Current treatments have limited efficacy and often cause severe side effects. Wuwei Shaji Powder (WSP), a traditional Mongolian remedy, is used for treating chronic pulmonary diseases, but its efficacy against asthma and underlying mechanisms are still unclear.

AIM OF THE STUDY

To investigate the therapeutic effect of WSP on asthma and elucidate its molecular mechanisms.

MATERIALS AND METHODS

An ovalbumin (OVA)-induced allergic asthma model was established in rats. Ferroptosis or apoptosis was induced in BEAS-2B cells using Erastin or CdCl2. Various techniques including histopathological staining, ELISA, Western blot, flow cytometry, and transmission electron microscopy were employed to assess WSP's effects and mechanisms.

RESULTS

WSP alleviated OVA-induced allergic asthma in rats without the immunosuppressive side effects observed with dexamethasone. WSP suppressed ferroptosis in bronchial epithelial cells both in vivo and in vitro. It reduced thiol- and sulfonic-based oxidative stress through Keap1 S-sulfhydration, disrupted the Keap1-Nrf2 interaction, and promoted Nrf2 nuclear translocation. Notably, we discovered that CdCl2 can induce ferroptosis in BEAS-2B cells, and WSP prevented both ferroptosis and apoptosis in these cells.

CONCLUSION

WSP alleviates OVA-induced allergic asthma by protecting bronchial epithelial cells from ferroptosis via S-sulfhydration of Keap1, providing new insights for its clinical application.

Discrepancies between human and murine model cerebral aneurysms at single-cell resolution

Background

The murine model of cerebral aneurysm (CA) serves as a prevalent tool for investigating the molecular underpinnings of CA. However, the extent to which the CA murine model aligns with that of human remains elusive.

Methods

The present study employed a comprehensive integration and exploration of the single-cell RNA-seq (scRNA-seq) datasets, along with multiple trajectory and gene regulatory network analyses, to investigate the cellular and molecular discrepancies between human and murine model CAs.

Results

The uniform manifold approximation and projection (umap) embedding exhibits that the primary discrepancies between human and murine model CAs reside in the cells of modifiable phenotype, encompassing vascular smooth muscle cell (vSMC), monocyte/macrophage, and neutrophil. The vSMCs from human CA tissue exhibit a fibroblast-like phenotype in comparison to that of murine model. Distinct patterns of neutrophil recruitment are observed in human and murine models, with the former characterized by neutrophil-derived CXCL8 and the latter by monocyte/macrophage-derived CCLs. In addition, macrophages originated from human unruptured CA express higher levels of M2 gene markers. Moreover, the inflammatory status of the CA tissue differs between humans and mouse models, with the former exhibiting a more acute and intense inflammation.

Conclusion

These findings demonstrate subtle but important disparities between human and murine model CAs, and may shed light upon an optimization of murine CA model.

TREM2 alleviates sepsis-induced acute lung injury by attenuating ferroptosis via the SHP1/STAT3 pathway

Sepsis-induced acute lung injury (ALI) is a complex and life-threatening condition characterized by excessive inflammatory responses, ferroptosis, and oxidative stress. A comprehensive investigation and effective therapeutic strategies are crucial for managing this condition. In this study, we established in vivo sepsis models using lipopolysaccharide (LPS) in wild-type (WT) mice and triggering receptor expressed on myeloid cells 2 (TREM2) knockout (TREM2-KO) mice to assess lung morphology, oxidative stress, and ferroptosis. In vitro, RAW264.7 cells with TREM2 overexpression (TREM2-OE) or knockdown (TREM2-SiRNA) were utilized to assess oxidative stress and ferroptosis. RNA sequencing of LPS-stimulated cells transfected with either vector or TREM2-OE revealed significant differences in inflammation- and ferroptosis-related pathways. LPS-induced lung injury and ferroptosis were exacerbated in TREM2-KO mice and TREM2-SiRNA cells but alleviated by the ferroptosis inhibitor ferrostatin-1 (Fer-1). Mechanistically, TREM2-KO led to SHP1 downregulation and STAT3-P upregulation, which were reversed by the SHP1 agonist SC-43. These findings highlight the role of TREM2 in the SHP1/STAT3 signaling pathway and its regulatory effects on ferroptosis. Our study demonstrates that TREM2, via the SHP1/STAT3 pathway, suppresses oxidative stress and ferroptosis, thereby significantly mitigating sepsis-induced ALI. These results underscore the pivotal role of TREM2 in modulating inflammatory responses and immunity, providing a theoretical foundation for developing therapeutic strategies.

Irf7 aggravates prostatitis by promoting Hif-1α-mediated glycolysis to facilitate M1 polarization

BACKGROUND

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a common disorder associated with voiding symptoms and pain in the pelvic or perineal area. Macrophages, particularly the pro-inflammatory M1 subtype, are crucial initiating of CP/CPPS. Interferon regulatory factor 7 (Irf7) has been implicated in promoting M1 polarization, contributing to the onset and progression of autoimmunity. However, the role of Irf7 in the etiology and progression of CP/CPPS remains unclear.

METHOD

We established the experimental autoimmune prostatitis (EAP) mouse model by subcutaneous injection of prostate antigen combined with complete Freund's adjuvant. Six weeks after the first immunization, we analyzed the prostates, spleen, and blood to assess the degree of prostate inflammation, Irf7 expression levels, glycolysis, and M1 polarization to evaluate whether Irf7 could exacerbate the development of EAP by enhancing Hif-1α transcription, thereby increasing glycolysis and M1 polarization. Further investigations included sh-Irf7 intervention, Dimethyloxalylglycine (a Hif-1α agonist), and in vitro M1 polarization experiments. We also employed ChIP assays, dual-luciferase reporter assays, and q-PCR to explore if Irf7 could directly interact with the Hif-1α promoter in macrophages.

RESULTS

In the EAP mouse and cell models, elevated Irf7 expression was observed in inflamed tissues and cells. Reducing Irf7 expression decreased M1 cell glycolysis by inhibiting the nuclear translocation of Hif-1α, thus mitigating M1 cell polarization. Additionally, Irf7 was identified as a transcription factor that regulates Hif-1α transcription by interacting with its promoter in macrophages, confirmed through ChIP and dual-luciferase assays. Co-culturing macrophage cells with 3T3 fibroblasts with reduced Irf7 levels resulted in decreased fibrosis, and a significant reduction in prostate tissue fibrosis was noted in mice with Irf7 knockdown.

CONCLUSION

Our findings indicate that Irf7 can contribute to the development and progression of CP/CPPS by promoting glycolysis, which can enhance both M1 polarization as well as interstitial fibrosis in the prostate. This process was found to be mediated by the upregulation of Hif-1α transcription, presenting new potential therapeutic targets for managing CP/CPPS.

Targeting ferroptosis offers therapy choice in sepsis-associated acute lung injury

Sepsis-associated acute lung injury (SALI) is a common complication of sepsis, consisting of a dysfunctional host response to infection-mediated heterogenous complexes. SALI is reported in up to 50 % of patients with sepsis and causes poor outcomes. Despite high incidence, there is a lack of understanding in its pathogenesis and optimal treatment. A better understanding of the molecular mechanisms underlying SALI may help produce better therapeutics. The effects of altered cell-death mechanisms, such as non-apoptotic regulated cell death (RCD) (i.e., ferroptosis), on the development of SALI are beginning to be discovered, while targeting ferroptosis as a meaningful target in SALI is increasingly being recognized. Here, we outline how a susceptible lung alveoli may develop SALI. Then we discuss the general mechanisms underlying ferroptosis, and how it contributes to SALI. We then outline the chemical structures of the emerging agents or compounds that can protect against SALI by inhibiting ferroptosis, summarizing their potential pharmacological effects. Finally, we highlight key limitations and possible strategies to overcome them. This review suggests that a detailed mechanistic and biological understanding of ferroptosis can foster the development of pharmacological antagonists in the treatment of SALI.

TRIM11 modulates sepsis progression by promoting HOXB9 ubiquitination and inducing the NF-κB signaling pathway

INTRODUCTION

The purpose of this investigation was to elucidate the functions of TRIM11 and HOXB9 in the pathogenesis of sepsis, focusing on their influence on inflammation, apoptosis, and the NF-κB signaling pathway.

MATERIAL AND METHODS

Through public databases, TRIM family genes related to sepsis were screened, and TRIM11 was evaluated as a sepsis biomarker through ROC analysis. The UbiBrowser database screened TRIM11 downstream genes and identified HOXB9 as an essential target. THP-1 cells were stimulated by Lipopolysaccharide (LPS) to induce inflammation and simulate sepsis. Flow cytometry, Enzyme-linked immunosorbent assay, and Western blot experiments were used to detect changes in cell apoptosis rate, apoptosis-related proteins, and inflammatory cytokines after TRIM11 and HOXB9 were silenced. Additionally, we investigated the ubiquitination interaction between TRIM11 and HOXB9 and their effects on the NF-κB signaling pathway.

RESULTS

Our findings demonstrated that sepsis patient samples had elevated levels of TRIM11 expression and had high clinical diagnostic value. Functional experiments showed that the knockdown of TRIM11 significantly alleviated LPS-induced THP-1 cell apoptosis and inflammation, while the knockdown of HOXB9 did the opposite. The simultaneous downregulation of TRIM11 and HOXB9 balanced these responses, suggesting they play a key role in regulating sepsis-associated inflammation and apoptosis. In addition, TRIM11 regulated the NF-κB signaling pathway by reversing HOXB9-induced activation through ubiquitination, suggesting a novel regulatory mechanism in the pathogenesis of sepsis.

CONCLUSIONS

Our findings highlight the interaction between TRIM11 and HOXB9 in regulating inflammation and apoptosis pathways, providing new insights into sepsis treatment.

IRF7 Activates LCN2 Transcription to Enhance LPS-Induced Acute Lung Injury by Inducing Macrophage Ferroptosis and M1 Polarization

Acute lung injury (ALI), a severe pulmonary disorder that poses a significant threat to life, is closely associated with macrophage ferroptosis and polarization. Lipocalin 2 (LCN2) has been previously reported to be implicated in the pathogenesis of ALI. However, the specific role of LCN2 in macrophage ferroptosis and polarization remains undetermined. Lipopolysaccharide (LPS) was used to establish a mouse model of ALI and also to stimulate mouse RAW264.7 cells. H&E staining was used for histopathologic evaluation, and immunohistochemistry analysis was used to determine the 4-HNE-positive cells. The secretion levels of TNF-α, IL-6, and IL-1β were assessed by ELISA. Gene and protein expression assays were performed using quantitative PCR and immunoblotting. The levels of MDA, GSH, ROS, and lipid ROS were detected to evaluate the alteration in ferroptosis. CD86+ and CD206+ cells were quantified by flow cytometry. The relationship between LCN2 and interferon regulatory factor 7 (IRF7) was confirmed by chromatin immunoprecipitation (ChIP) and luciferase reporter assays. LCN2 expression was upregulated in the lungs of LPS-induced ALI mice and LPS-stimulated RAW264.7 cells. In LPS-induced ALI mice, the depletion of LCN2 alleviated lung injury and ferroptosis, and also inhibited inflammation and macrophage M1 polarization. In LPS-stimulated RAW264.7 cells, the depletion of LCN2 suppressed ferroptosis, inflammation, and M1 polarization. Mechanistically, IRF7 enhanced LCN2 transcription in RAW264.7 cells by binding to its promoter region. More importantly, the silencing of IRF7 inhibited ferroptosis and M1 polarization in LPS-stimulated RAW264.7 cells by downregulating LCN2. Taken together, the IRF7/LCN2 cascade enhances the ferroptosis and M1 polarization of LPS-stimulated macrophages, thereby exacerbating ALI. Anti-IRF7 and anti-LCN2 therapies might potentially be exploited for the prevention and treatment in ALI.

NLRP3 regulates ferroptosis via the JAK2/STAT3 pathway in asthma inflammation: Insights from in vivo and in vitro studies

BACKGROUND

Ferroptosis, an iron-dependent form of cell death, plays a pivotal role in the pathologic progression of asthma. Electroacupuncture (EA) has demonstrated considerable efficacy in mitigating asthma airway inflammation, although its underlying mechanisms remain partially elucidated.

METHODS

We investigated the regulatory effect of NLRP3 on ferroptosis using a lipopolysaccharide (LPS)-induced inflammation model in BEAS-2B cells, where NLRP3 expression was modulated with si-RNA and overexpression plasmids. The levels of inflammatory cytokines TNF-α, IL-1β, and IL-6 were quantified. We also assessed NLRP3 and JAK2/STAT3 pathway-related proteins, and evaluated lipid peroxidation, mitochondrial membrane potential (ΔΨm), and antioxidant system functionality. In vivo, we examined the impact of EA on ferroptosis and airway inflammation by modulating NLRP3 activation. Asthma inflammation severity was evaluated using H&E, Masson, and PAS staining, alongside ELISA. NLRP3 and JAK2/STAT3 pathway-related proteins, as well as ferroptosis indicators, were also analyzed. The mechanism by which NLRP3 activates ferroptosis was investigated through in vitro assays.

RESULTS

LPS exposure resulted in increased intracellular inflammatory cytokines, and activation of the NLRP3 and JAK2/STAT3 pathways, leading to enhanced lipid peroxidation, decreased ΔΨm, and disruption of antioxidant system balance, ultimately inducing ferroptosis. Si-NLRP3 countered the effects of LPS, whereas oe-NLRP3 exacerbated symptoms. In vivo studies revealed that EA reduced airway inflammation, inhibited NLRP3 activation, and decreased phosphorylation of JAK2/STAT3, effectively lowering ferroptosis-related indicators. Utilizing JAK2/STAT3 activators and inhibitors, we confirmed that NLRP3 mediates ferroptosis via the JAK2/STAT3 pathway.

CONCLUSIONS

EA alleviates HDM-induced asthma, primarily through the inhibition of NLRP3 activation, which modulates the JAK2/STAT3 pathway and mediates ferroptosis.

Exploring and Validating the Mechanism of Ulinastatin in the Treatment of Sepsis-Associated Encephalopathy Based on Transcriptome Sequencing

Purpose

Sepsis can induce sepsis-associated encephalopathy (SAE), with Ulinastatin (UTI) serving a critical anti-inflammatory role. This study aimed to identify the hub genes in an SAE mouse model following UTI intervention and investigate the underlying molecular mechanisms.

Materials and Methods

Through differential expression analysis to obtain differentially expressed genes (DEGs), ie, UTI vs CLP (DEGs1) and Con vs CLP (DEGs2). After taking the intersection of the genes with opposite differential trends in these two parts and immune-related genes (IRGs), DE-IRGs were obtained. Hub genes in the protein-protein interaction (PPI) network were then determined using six algorithms from the Cytohubba plugin in Cytoscape. Gene set enrichment analysis (GSEA) was employed to explore the functional relevance of these hub genes. Additionally, the immune microenvironment across the three groups was compared, and hub gene-related drugs were predicted using an online database. Finally, qRT-PCR was used to validate the expression of the hub genes in hippocampal tissue from CLP mice.

Results

RNA sequencing obtained 864 differentially expressed genes (DEGs) (CLP vs Con) and 279 DEGs (UTI vs CLP). Taking the intersection of DEGs with opposite expression trends yielded 165 DEGs. Six key genes (ICAM - 1, IRF7, IL - 1β, CCL2, IL - 6 and SOCS3) were screened by six algorithms. Immune infiltration analysis found that Treg cells were reversed after treatment with UTI in the diseased state. A total of 106 hub - gene - related drugs were predicted, among which BINDARIT - CCL2 and LIFITEGRAST - ICAM1 showed particularly high affinities. The qRT - PCR verification results were consistent with the sequencing results.

Conclusion

In conclusion, ICAM-1, IRF7, IL-1β, CCL2, IL-6, and SOCS3 were identified as potential therapeutic targets in SAE mice treated with UTI. This study offers theoretical support for UTI as a treatment option for SAE.

Mitophagy and Ferroptosis in Sepsis-Induced ALI/ARDS: Molecular Mechanisms, Interactions and Therapeutic Prospects of Medicinal Plants

Sepsis is a common critical illness characterized by high mortality rates and a significant disease burden. In the context of sepsis-induced organ dysfunction, the lungs are among the initial organs affected, which may progress to acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Recent studies have highlighted the crucial roles of mitophagy and ferroptosis in the development and progression of sepsis-induced ALI/ARDS. Identifying key convergence points in these processes may provide valuable insights for the treatment of this condition. In recent years, certain herbs and their bioactive compounds have demonstrated unique benefits in managing sepsis-induced ALI/ARDS by modulating mitophagy or ferroptosis. This review summary the mechanisms of mitophagy and ferroptosis, explores their interactions, and emphasizes their regulatory roles in the progression of sepsis-induced ALI/ARDS. Additionally, it offers a novel perspective on treatment strategies by summarizing various herbs and their bioactive compounds relevant to this condition.

Relationship between ferroptosis and mitophagy in acute lung injury: a mini-review

Acute lung injury (ALI) is one of the most deadly and prevalent diseases in the intensive care unit. Ferroptosis and mitophagy are pathological mechanisms of ALI. Ferroptosis aggravates ALI, whereas mitophagy regulates ALI. Ferroptosis and mitophagy are both closely related to reactive oxygen species (ROS). Mitophagy can regulate ferroptosis, but the specific relationship between ferroptosis and mitophagy is still unclear. This study summarizes previous research findings on ferroptosis and mitophagy, revealing their involvement in ALI. Examining the functions of mTOR and NLPR3 helps clarify the connection between ferroptosis and mitophagy in ALI, with the goal of establishing a theoretical foundation for potential therapeutic approaches in the future management of ALI.

Mir22hg facilitates ferritinophagy-mediated ferroptosis in sepsis by recruiting the m6A reader YTHDC1 and enhancing Angptl4 mRNA stability

BACKGROUND

Ferritinophagy-mediated ferroptosis plays a crucial role in fighting pathogen aggression. The long non-coding RNA Mir22hg is involved in the regulation of ferroptosis and aberrantly overexpression in lipopolysaccharide (LPS)-induced sepsis mice, but whether it regulates sepsis through ferritinophagy-mediated ferroptosis is unclear.

METHODS

Mir22hg was screened by bioinformatics analysis. Ferroptosis was assessed by assaying malondialdehyde (MDA), reactive oxygen species (ROS), and Fe2+ levels, glutathione (GSH) activity, as well as ferroptosis-related proteins GPX4 and SLC3A2 by using matched kits and performing western blot. Ferritinophagy was assessed by Lyso tracker staining and FerroOrange staining, immunofluorescence analysis of Ferritin and LC-3, and western blot analysis of LC-3II/I, p62, FTH1, and NCOA4. The bind of YTH domain containing 1 (YTHDC1) to Mir22hg or angiopoietin-like-4 (Angptl4) was verified by RNA pull-down and/or immunoprecipitation (RIP) assays.

RESULTS

Mir22hg silencing lightened ferroptosis and ferritinophagy in LPS-induced MLE-12 cells and sepsis mouse models, as presented by the downregulated MDA, ROS, Fe2+, NCOA4, and SLC3A2 levels, upregulated GPX4, GSH, and FTH1 levels, along with a decrease in autophagy. Mir22hg could bind to the m6A reader YTHDC1 without affecting its expression. Mechanistically, Mir22hg enhanced Angptl4 mRNA stability through recruiting the m6A reader YTHDC1. Furthermore, Angptl4 overexpression partly overturned Mir22hg inhibition-mediated effects on ferroptosis and ferritinophagy in LPS-induced MLE-12 cells.

CONCLUSION

Mir22hg contributed to in ferritinophagy-mediated ferroptosis in sepsis via recruiting the m6A reader YTHDC1 and strengthening Angptl4 mRNA stability, highlighting that Mir22hg may be a potential target for sepsis treatment based on ferroptosis.

Targeting BRD4 with PROTAC degrader ameliorates LPS-induced acute lung injury by inhibiting M1 alveolar macrophage polarization

OBJECTIVES

Acute lung injury (ALI) is a highly inflammatory condition with the involvement of M1 alveolar macrophages (AMs) polarization, eventually leading to the development of non-cardiogenic edema in alveolar and interstitial regions, accompanied by persistent hypoxemia. Given the significant mortality rate associated with ALI, it is imperative to investigate the underlying mechanisms of this condition so as to identify potential therapeutic targets. The therapeutic effects of the inhibition of bromodomain containing protein 4 (BRD4), an epigenetic reader, has been proven with high efficacy in ameliorating various inflammatory diseases through mediating immune cell activation. However, little is known about the therapeutic potential of BRD4 degradation in acute lung injury.

METHODS

This study aimed to assess the protective efficacy of ARV-825, a novel BRD4-targeted proteolysis targeting chimera (PROTAC), against ALI through histopathological examination in lung tissues and biochemical analysis in bronchoalveolar lavage fluid (BALF). Additionally, the underlying mechanism by which BRD4 regulated M1 AMs was elucidated by using CUT & Tag assay.

RESULTS

In this study, we found the upregulation of BRD4 in a lipopolysaccharide (LPS)-induced ALI model. Furthermore, we observed that intraperitoneal administration of ARV-825, significantly alleviated LPS-induced pulmonary pathological changes and inflammatory responses. These effects were accompanied by the suppression of M1 AMs. In addition, our findings revealed that the administration of ARV-825 effectively suppressed M1 AMs by inhibiting the expression of IRF7, a crucial transcriptional factor involved in M1 macrophages.

CONCLUSION

Our study suggested that targeting BRD4 using ARV-825 is a potential therapeutic approach for ALI.

Mitochondrial (mt)DNA-cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling promotes pyroptosis of macrophages via interferon regulatory factor (IRF)7/IRF3 activation to aggravate lung injury during severe acute pancreatitis

BACKGROUND

Macrophage proinflammatory activation contributes to the pathology of severe acute pancreatitis (SAP) and, simultaneously, macrophage functional changes, and increased pyroptosis/necrosis can further exacerbate the cellular immune suppression during the process of SAP, where cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) plays an important role. However, the function and mechanism of cGAS-STING in SAP-induced lung injury (LI) remains unknown.

METHODS

Lipopolysaccharide (LPS) was combined with caerulein-induced SAP in wild type, cGAS -/- and sting -/- mice. Primary macrophages were extracted via bronchoalveolar lavage and peritoneal lavage. Ana-1 cells were pretreated with LPS and stimulated with nigericin sodium salt to induce pyroptosis in vitro.

RESULTS

SAP triggered NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome activation-mediated pyroptosis of alveolar and peritoneal macrophages in mouse model. Knockout of cGAS/STING could ameliorate NLRP3 activation and macrophage pyroptosis. In addition, mitochondrial (mt)DNA released from damaged mitochondria further induced macrophage STING activation in a cGAS- and dose-dependent manner. Upregulated STING signal can promote NLRP3 inflammasome-mediated macrophage pyroptosis and increase serum interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α levels and, thus, exacerbate SAP-associated LI (SAP-ALI). Downstream molecules of STING, IRF7, and IRF3 connect the mtDNA-cGAS-STING axis and the NLRP3-pyroptosis axis.

CONCLUSIONS

Negative regulation of any molecule in the mtDNA-cGAS-STING-IRF7/IRF3 pathway can affect the activation of NLRP3 inflammasomes, thereby reducing macrophage pyroptosis and improving SAP-ALI in mouse model.

Obesity-induced downregulation of miR-192 exacerbates lipopolysaccharide-induced acute lung injury by promoting macrophage activation

BACKGROUND

Macrophage activation may play a crucial role in the increased susceptibility of obese individuals to acute lung injury (ALI). Dysregulation of miRNA, which is involved in various inflammatory diseases, is often observed in obesity. This study aimed to investigate the role of miR-192 in lipopolysaccharide (LPS)-induced ALI in obese mice and its mechanism of dysregulation in obesity.

METHODS

Human lung tissues were obtained from obese patients (BMI ≥ 30.0 kg/m2) and control patients (BMI 18.5-24.9 kg/m2). An obese mouse model was established by feeding a high-fat diet (HFD), followed by intratracheal instillation of LPS to induce ALI. Pulmonary macrophages of obese mice were depleted through intratracheal instillation of clodronate liposomes. The expression of miR-192 was examined in lung tissues, primary alveolar macrophages (AMs), and the mouse alveolar macrophage cell line (MH-S) using RT-qPCR. m6A quantification and RIP assays helped determine the cause of miR-192 dysregulation. miR-192 agomir and antagomir were used to investigate its function in mice and MH-S cells. Bioinformatics and dual-luciferase reporter gene assays were used to explore the downstream targets of miR-192.

RESULTS

In obese mice, depletion of macrophages significantly alleviated lung tissue inflammation and injury, regardless of LPS challenge. miR-192 expression in lung tissues and alveolar macrophages was diminished during obesity and further decreased with LPS stimulation. Obesity-induced overexpression of FTO decreased the m6A modification of pri-miR-192, inhibiting the generation of miR-192. In vitro, inhibition of miR-192 enhanced LPS-induced polarization of M1 macrophages and activation of the AKT/ NF-κB inflammatory pathway, while overexpression of miR-192 suppressed these reactions. BIG1 was confirmed as a target gene of miR-192, and its overexpression offset the protective effects of miR-192. In vivo, when miR-192 was overexpressed in obese mice, the activation of pulmonary macrophages and the extent of lung injury were significantly improved upon LPS challenge.

CONCLUSIONS

Our study indicates that obesity-induced downregulation of miR-192 expression exacerbates LPS-induced ALI by promoting macrophage activation. Targeting macrophages and miR-192 may provide new therapeutic avenues for obesity-associated ALI.

YBX-1 alleviates sepsis-stimulated lung epithelial cell injury

OBJECTIVE

To explore the role of Y-box binding protein 1 (YBX-1) in the lipopolysaccharide (LPS)-stimulated inflammation and oxidative stress of BEAS-2B cell line and clarify the underlying mechanism.

METHODS

LPS-stimulated BEAS-2B cells were used as a cell model of sepsis-stimulated acute lung injury (ALI). Immunoblot and quantitative polymerase chain reaction assays were used to detect the expression of YBX-1 in LPS-stimulated BEAS-2B cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide, TdT-mediated dUTP nick end labeling, and immunoblot assays were conducted to determine the effects of YBX-1 on cell survival. JC-1 staining and adenosine triphosphate production were used to detect the effects of YBX-1 on mitochondrial function. Immunostaining and enzyme-linked immunosorbent serologic assay were performed to examine the effects of YBX-1 on the inflammation and oxidative stress of cells. Immunoblot assay was conducted to confirm the mechanism.

RESULTS

YBX-1 was lowly expressed in LPS-stimulated BEAS-2B cells and enhanced the survival of LPS-stimulated lung epithelial cells. In addition, YBX-1 improved mitochondrial function of LPS-stimulated BEAS-2B cells. YBX-1 inhibited the inflammation and oxidative stress of LPS-stimulated BEAS-2B cells. Mechanically, YBX-1 inhibited mitogen-activated protein kinase (MAPK) axis, thereby alleviating sepsis-stimulated ALI.

CONCLUSION

YBX-1 alleviated inflammation and oxidative stress of LPS-stimulated BEAS-2B cells via MAPK axis.