MicroRNA-451 from Human Umbilical Cord-Derived Mesenchymal Stem Cell Exosomes Inhibits Alveolar Macrophage Autophagy via Tuberous Sclerosis Complex 1/Mammalian Target of Rapamycin Pathway to Attenuate Burn-Induced Acute Lung Injury in Rats.

Objective: Our previous studies established that microRNA (miR)-451 from human umbilical cord mesenchymal stem cell-derived exosomes (hUC-MSC-Exos) alleviates acute lung injury (ALI). This study aims to elucidate the mechanisms by which miR-451 in hUC-MSC-Exos reduces ALI by modulating macrophage autophagy. Methods: Exosomes were isolated from hUC-MSCs. Severe burn-induced ALI rat models were treated with hUC-MSC-Exos carrying the miR-451 inhibitor. Hematoxylin-eosin staining evaluated inflammatory injury. Enzyme-linked immunosorbnent assay measured lipopolysaccharide (LPS), tumor necrosis factor-α, and interleukin-1ß levels. qRT-PCR detected miR-451 and tuberous sclerosis complex 1 (TSC1) expressions. The regulatory role of miR-451 on TSC1 was determined using a dual-luciferase reporter system. Western blotting determined TSC1 and proteins related to the mammalian target of rapamycin (mTOR) pathway and autophagy. Immunofluorescence analysis was conducted to examine exosomes phagocytosis in alveolar macrophages and autophagy level. Results: hUC-MSC-Exos with miR-451 inhibitor reduced burn-induced ALI and promoted macrophage autophagy. MiR-451 could be transferred from hUC-MSCs to alveolar macrophages via exosomes and directly targeted TSC1. Inhibiting miR-451 in hUC-MSC-Exos elevated TSC1 expression and inactivated the mTOR pathway in alveolar macrophages. Silencing TSC1 activated mTOR signaling and inhibited autophagy, while TSC1 knockdown reversed the autophagy from the miR-451 inhibitor-induced. Conclusion: miR-451 from hUC-MSC exosomes improves ALI by suppressing alveolar macrophage autophagy through modulation of the TSC1/mTOR pathway, providing a potential therapeutic strategy for ALI.

Regulatory mechanism of TRIM21 in sepsis-induced acute lung injury by promoting IRF1 ubiquitination.

Sepsis-induced acute lung injury (ALI) is characterized by inflammatory damage to pulmonary endothelial and epithelial cells. The aim of this study is to probe the significance and mechanism of tripartite motif-containing protein 21 (TRIM21) in sepsis-induced ALI. The sepsis-induced ALI mouse model was established by cecum ligation and puncture. The mice were infected with lentivirus and treated with proteasome inhibitor MG132. The lung respiratory damage, levels of interleukin-6 (IL-6), tumour necrosis factor α (TNF-α), IL-10 and pathological changes were observed. The expression levels of TRIM21, interferon regulatory factors 1 (IRF1) and triggering receptor expressed on myeloid cells 2 (TREM2) were measured and their interactions were analysed. The ubiquitination level of IRF1 was detected. TRIM21 and TREM2 were downregulated and IRF1 was upregulated in sepsis-induced ALI mice. TRIM21 overexpression eased inflammation and lung injury. TRIM21 promoted IRF1 degradation via ubiquitination modification. IRF1 bonded to the TREM2 promoter to inhibit its transcription. Overexpression of IRF1 or silencing TREM2 reversed the improvement of TRIM21 overexpression on lung injury in mice. In conclusion, TRIM21 reduced IRF1 expression by ubiquitination to improve TREM2 expression and ameliorate sepsis-induced ALI.

Deciphering regulatory patterns in a mouse model of hyperoxia-induced acute lung injury.

Background: Oxygen therapy plays a pivotal role in treating critically ill patients in the intensive care unit (ICU). However, excessive oxygen concentrations can precipitate hyperoxia, leading to damage in multiple organs, with a notable effect on the lungs. Hyperoxia condition may lead to hyperoxia-induced acute lung injury (HALI), deemed as a milder form of acute respiratory distress syndrome (ARDS). Given its clinical importance and practical implications, there is a compelling need to investigate the underlying pathogenesis and comprehensively understand the regulatory mechanisms implicated in the development of HALI. Results: In this study, we conducted a mouse model with HALI and performed regulatory mechanism analysis using RNA-seq on both HALI and control group. Comprehensive analysis revealed 727 genes of significant differential expression, including 248 long non-coding RNAs (lncRNAs). Also, alternative splicing events were identified from sequencing results. Notably, we observed up-regulation or abnormal alternative splicing of genes associated with immune response and ferroptosis under hyperoxia conditions. Utilizing weighted gene co-expression network analysis (WGCNA), we ascertained that genes involved in immune response formed a distinct cluster, showcasing an up-regulated pattern in hyperoxia, consistent with previous studies. Furthermore, a competing endogenous RNA (ceRNA) network was constructed, including 78 differentially expressed mRNAs and six differentially expressed lncRNAs, including H19. These findings uncover the intricate interplay of multiple transcriptional regulatory mechanisms specifically tailored to the pulmonary defense against HALI, substantiating the importance of these non-coding RNAs in this disease context. Conclusions: Our results provide new insights into the potential mechanisms and underlying pathogenesis in the development of HALI at the post-transcriptional level. The findings of this study reveal potential regulatory interactions and biological roles of specific lncRNAs and genes, such as H19 and Sox9, encompassing driven gene expression patterns, alternative splicing events, and lncRNA-miRNA-mRNA ceRNA networks. These findings may pave the way for advancing therapeutic strategies and reducing the risk associated with oxygen treatment for patients.

Emodin alleviates lung injury via the miR-217-5p/Sirt1 axis in rats with severe acute pancreatitis.

Acute lung injury (ALI) is closely related to high mortality in severe acute pancreatitis (SAP). This study unveils the therapeutic effect and mechanism of miR-217-5p on SAP-associated ALI. The miR-217-5p RNA expression was significantly up-regulated in lipopolysaccharide (LPS)-stimulated primary rat alveolar epithelial type II cells (AEC II) and sodium taurocholate-treated pancreas and lung in SAP rats. miR-217 inhibition protected AEC II from LPS-induced damage by inhibiting apoptosis and reducing the TNF-α, IL-6, and ROS levels. miR-217 inhibition suppressed apoptosis and alleviated mitochondrial damage through mitochondria-mediated apoptotic pathway in vitro. Sirt1 is a direct target of miR-217-5p. Dual-luciferase reporter assay confirmed the binding of miR-217-5p to Sirt1 mRNA 3'-UTR. The rescue experiment identified that the anti-apoptotic, anti-inflammatory, and anti-oxidative effects of miR-217 inhibition were mediated by Sirt1 in vitro. Emodin (EMO) protected AEC II from LPS-induced damage and alleviated pancreatic and lung tissue injuries. EMO exerted similar effects as miR-217 inhibition in vitro and in vivo. The effects of EMO were abolished by miR-217 overexpression. In conclusion, miR-217-5p inhibition exerts protective effects on SAP-ALI in vitro and in vivo by repressing apoptosis, inflammation, and oxidative stress through Sirt1 activation. EMO protects against lung injuries in SAP-associated ALI rats through miR-217-5p/Sirt1 axis.

Epigenetic mechanism of EZH2-mediated histone methylation modification in regulating ferroptosis of alveolar epithelial cells in sepsis-induced acute lung injury.

Sepsis-induced acute lung injury (SI-ALI) leads to significant deaths in critically ill patients worldwide. This study explores the mechanism of EZH2 regulating ferroptosis of alveolar epithelial cells (AECs) in SI-ALI. In vitro cell model and in vivo mouse lung injury model of sepsis were established. EZH2 expression in lung tissues was intervened by sh-EZH2, followed by H&E staining observation of lung tissue pathological changes. EZH2, H3K27me3, USP10, GPX4, and ACSL4 expressions were determined by qRT-PCR or Western blot. ROS, GSH, and iron ion levels were detected using fluorescent labeling and reagent kits, respectively. ChIP analyzed the enrichment of EZH2 and H3K27me3 on USP10 promoter. The binding between USP10 and GPX4, and the ubiquitination level of GPX4 were detected using Co-IP. EZH2 was highly expressed in lung tissues of SI-ALI mice. EZH2 silencing alleviated ALI and ferroptosis of AECs; EZH2 increased the H3K27me3 level on USP10 promoter through histone methylation. USP10 stabilized GPX4 protein expression through ubiquitination; inhibition of USP10 partially reversed the inhibitory effect of EZH2 silencing on ferroptosis of AECs. In conclusion, EZH2 depresses USP10 expression by promoting histone H3K27me3 modification on USP10 promoter, thereby enhancing ubiquitination degradation of GPX4 and ultimately facilitating ferroptosis of AECs in sepsis.

Estrogen-dependent gene regulation: Molecular basis of TIMP-1 as a sex-specific biomarker for acute lung injury.

Increased circulating tissue inhibitor of metalloproteinases-1 (TIMP-1) levels have been observed in patients with acute lung injury (ALI). However, the sex-specific regulation of TIMP-1 and the underlying molecular mechanisms have not been well elucidated. In this study, we found that plasma TIMP-1 levels were significantly higher in COVID-19 and H1N1 patients compared with those in healthy subjects (n = 25). TIMP-1 concentrations were significantly different between males and females in each disease group. Among female but not male patients, TIMP-1 levels significantly correlated with the PaO2/FiO2 ratio and hospital length of stay. Using the mouse model of ALI induced by the H1N1 virus, we found that TIMP-1 is strikingly induced in PDGFRα-positive cells in the murine lungs. Moreover, female mice showed a higher Timp-1 expression in the lungs on day 3 postinfection. Mechanistically, we observed that estrogen can upregulate TIMP-1 expression in lung fibroblasts, not epithelial cells. In addition, overexpression of estrogen receptor α (ERα) increased the TIMP-1 promoter activity. In summary, TIMP-1 is an estrogen-responsive gene, and its promoter activity is regulated by ERα. Circulating TIMP-1 may serve as a sex-specific marker, reflecting the severity and worst outcomes in female patients with SARS-CoV2- and IAV-related ALI.

RAMP1 Signaling Mitigates Acute Lung Injury by Distinctively Regulating Alveolar and Monocyte-Derived Macrophages.

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury that induces cytokine hypersecretion. Receptor activity-modifying protein (RAMP) 1, a subunit of the calcitonin gene-related peptide (CGRP) receptor, regulates the production of cytokines. This study examined the role of RAMP1 signaling during lipopolysaccharide (LPS)-induced acute lung injury (ALI). LPS administration to wild-type (WT) mice depleted alveolar macrophages (AMs) and recruited monocyte-derived macrophages (MDMs) and neutrophils. RAMP1-deficient (RAMP1-/-) mice exhibited higher lung injury scores, cytokine levels, and cytokine-producing neutrophil infiltration. RAMP1-deficient AMs produced more cytokines in response to LPS than WT AMs. Adoptive transfer of RAMP1-deficient AMs to RAMP1-/- mice increased cytokine levels and neutrophil accumulation compared to the transfer of WT AMs. RAMP1-/- mice had reduced MDM recruitment and lower pro-inflammatory and reparative macrophage profiles. Cultured bone marrow (BM)-derived RAMP1-deficient macrophages stimulated with LPS showed decreased expression of pro-inflammatory and pro-repairing genes. CGRP administration to WT mice reduced cytokine production and neutrophil accumulation. These findings indicate that RAMP1 signaling mitigates LPS-induced ALI by inactivating AMs and promoting inflammatory and repair activities of MDMs. Targeting RAMP1 signaling presents a potential therapeutic approach for the treatment of ARDS.

Alveolar epithelial cells mitigate neutrophilic inflammation in lung injury through regulating mitochondrial fatty acid oxidation.

Type 2 alveolar epithelial (AT2) cells of the lung are fundamental in regulating alveolar inflammation in response to injury. Impaired mitochondrial long-chain fatty acid ß-oxidation (mtLCFAO) in AT2 cells is assumed to aggravate alveolar inflammation in acute lung injury (ALI), yet the importance of mtLCFAO to AT2 cell function needs to be defined. Here we show that expression of carnitine palmitoyltransferase 1a (CPT1a), a mtLCFAO rate limiting enzyme, in AT2 cells is significantly decreased in acute respiratory distress syndrome (ARDS). In mice, Cpt1a deletion in AT2 cells impairs mtLCFAO without reducing ATP production and alters surfactant phospholipid abundance in the alveoli. Impairing mtLCFAO in AT2 cells via deleting either Cpt1a or Acadl (acyl-CoA dehydrogenase long chain) restricts alveolar inflammation in ALI by hindering the production of the neutrophilic chemokine CXCL2 from AT2 cells. This study thus highlights mtLCFAO as immunometabolism to injury in AT2 cells and suggests impaired mtLCFAO in AT2 cells as an anti-inflammatory response in 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.

Tetramethylpyrazine ameliorates LPS-induced acute lung injury via the miR-369-3p/DSTN axis.

Acute lung injury (ALI) is a severe clinical respiratory condition characterized by high rates of mortality and morbidity, for which effective treatments are currently lacking. In this study, lipopolysaccharide (LPS) was used to induce ALI mice, demonstrating the efficacy of tetramethylpyrazine (TMP) in ameliorating ALI. Subsequent we perfored high-throughput sequencing analysis and used Targetscan 8.0 and miRWalk 3.0 databases to predict the interaction between microRNAs and destrin (DSTN), ultimately identifying miR-369-3p as the focus of the investigation. The adenovirus carrying miR-369-3p was administered one week prior to LPS-induced in order to assess its potential efficacy in ameliorating ALI in mice. The findings indicated that the overexpression of miR-369-3p resulted in enhanced lung function, reduced pulmonary edema, inflammation, and permeability in LPS-induced ALI mice, while the suppression of miR-369-3p exacerbated the damage in these mice. Furthermore, the beneficial effects of TMP on LPS-induced ALI were negated by the downregulation of miR-369-3p. The results of our study demonstrate that TMP mitigates LPS-induced ALI through upregulation of miR-369-3p. Consequently, the findings of this study advocate for the clinical utilization of TMP in ALI treatment, with miR-369-3p emerging as a promising target for future ALI interventions.

Electroacupuncture pretreatment maintains mitochondrial quality control via HO-1/MIC60 signaling pathway to alleviate endotoxin-induced acute lung injury.

Electroacupuncture has been demonstrated to mitigate endotoxin-induced acute lung injury by enhancing mitochondrial function. This study investigates whether electroacupuncture confers lung protection through the regulation of mitochondrial quality control mediated by heme oxygenase-1 (HO-1) and the mitochondrial inner membrane protein MIC60. HO-1, an inducible stress protein, is crucial for maintaining mitochondrial homeostasis and protecting against lung injury. MIC60, a key component of the mitochondrial contact site and cristae organizing system, supports mitochondrial integrity. We employed genetic knockout/silencing and cell transfection techniques to model lipopolysaccharide (LPS)-induced lung injury, assessing changes in mitochondrial structure, reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP), and the expression of proteins essential for mitochondrial quality control. Our findings reveal that electroacupuncture alleviates endotoxin-induced acute lung injury and associated mitochondrial dysfunction, as evidenced by reductions in lung injury scores, decreased ROS production, and suppressed expression of proteins involved in mitochondrial fission and mitophagy. Additionally, electroacupuncture enhanced MMP and upregulated proteins that facilitate mitochondrial fusion and biogenesis. Importantly, the protective effects of electroacupuncture were reduced in models with Hmox1 knockout or Mic60 silencing, and in macrophages transfected with Hmox1-siRNA or Mic60-siRNA. Moreover, HO-1 was found to influence MIC60 expression during electroacupuncture preconditioning and LPS challenge, demonstrating that these proteins not only co-localize but also interact directly. In conclusion, electroacupuncture effectively modulates mitochondrial quality control through the HO-1/MIC60 signaling pathway, offering an adjunctive therapeutic strategy to ameliorate endotoxin-induced acute lung injury in both in vivo and in vitro settings.

LncRNA SNHG1 knockdown attenuates lipopolysaccharide-induced acute lung injury via regulating miR199a-3p/ROCK2 axis.

Acute lung injury (ALI) is a significant health condition with notable rates of morbidity and mortality globally. Long non-coding ribose nucleic acids (lncRNAs) play vital roles in mitigating various inflammation-related diseases, including ALI. The study aimed to investigate the functional role and molecular mechanisms of lncRNA SNHG1 on ALI in lipopolysaccharide (LPS)-treated A549 cells and in LPS-induced ALI mice. The expression of SNHG1 was initially examined in LPS-treated A549 cells. We further demonstrated the critical function of SNHG1 through various cellular assessments following SNHG1 knockdown, including cell counting kit (CCK)-8 assay, flow cytometry analysis, as well as enzyme-linked immunosorbent assay (ELISA). Reducing SNHG1 levels hindered the negative effects of LPS on cell viability, apoptosis, and inflammation. Moreover, SNHG1 acted as a negative regulator for miR-199a-3p, which targeted downstream ROCK2. Depletion of miR-199a-3p or enhanced expression of ROCK2 abolished the protective effects of SNHG1 knockdown on LPS-induced apoptosis and inflammation. Consistently, silencing SNHG1 alleviated LPS-induced lung injury in mice, demonstrating its potential therapeutic benefits in managing ALI. Overall, this study sheds light on the role of SNHG1 in modulating inflammation and apoptosis in ALI through the miR-199a-3p/ROCK2 pathway, offering new insights for the treatment of this condition.

[Role and mechanism of ginsenoside Rg1 in ameliorating sepsis-induced acute lung injury based on PERK/eIF2α/ATF4/CHOP-induced alveolar epithelial cell apoptosis].

The study investigates the therapeutic effects and mechanisms of ginsenoside Rg_1(GRg_1) on sepsis-induced acute lung injury(SALI). A murine model of SALI was created using cecal ligation and puncture(CLP) surgery, and mice were randomly assigned to groups for GRg_1 intervention. Survival and body weight changes were recorded, lung function was assessed with a non-invasive lung function test system, and lung tissue damage was evaluated through HE staining. The content and expression of inflammatory factors were measured by ELISA and qRT-PCR. Apoptosis was examined using flow cytometry and TUNEL staining. The activation and expression of apoptosis-related molecules cysteinyl aspartate specific proteinase 3(caspase-3), B-cell lymphoma-2(Bcl-2), Bcl-2 associated X protein(Bax), and endoplasmic reticulum stress-related molecules protein kinase R-like endoplasmic reticulum kinase(PERK), eukaryotic initiation factor 2α(eIF2α), activating transcription factor 4(ATF4), and C/EBP homologous protein(CHOP) were studied using Western blot and qRT-PCR. In addition, an in vitro model of lipopolysaccharide(LPS)-induced lung alveolar epithelial cell injury was used, with the application of the endoplasmic reticulum stress inducer tunicamycin to validate the action mechanism of GRg_1. RESULTS:: indicated that, when compared to the model group, GRg_1 intervention significantly enhanced the survival time of CLP mice, mitigated body weight loss, and improved impaired lung function indices. The GRg_1-treated mice also displayed reduced lung tissue pathological scores, a reduced lung tissue wet-to-dry weight ratio, and lower protein content in the bronchoalveolar lavage fluid. Serum levels of interleukin-6(IL-6), interleukin-1ß(IL-1ß), and tumor necrosis factor-α(TNF-α), as well as the mRNA expressions of these cytokines in lung tissues, were decreased. There was a notable decrease in the proportion of apopto-tic alveolar epithelial cells, and down-regulated expressions of caspase-3, Bax, PERK, eIF2α, ATF4, and CHOP and up-regulated expression of Bcl-2 were observed. In vitro findings showed that the apoptosis-lowering and apoptosis-related protein down-regulating effects of GRg_1 were significantly inhibited with the co-application of tunicamycin. Altogether, GRg_1 reduces apoptosis of alveolar epithelial cells, inhibits inflammation in the lungs, alleviates lung injury, and enhances lung function, possibly through the PERK/eIF2α/ATF4/CHOP pathway.

SQSTM1 improves acute lung injury via inhibiting airway epithelium ferroptosis in a vitamin D receptor/autophagy-mediated manner.

Emerging evidence has reported that acute lung injury (ALI), characterized by inflammation and oxidative stress in airway epithelium, is regulated by programmed cell death. Ferroptosis, a regulated form of cell death spurred by uncontrolled lipid peroxidation, has been proven to implicate various diseases. Inhibiting ferroptosis represents a feasible strategy for ALI through the suppression of lipid peroxidation, while the mechanism remains to be further elucidated. Here, we identified Sequestosome 1 (SQSTM1) as a negative regulator of airway epithelium ferroptosis during ALI. SQSTM1 knockdown cells manifested higher sensitivity to ferroptosis. Mechanistically, SQSTM1 was found to directly interact with vitamin D receptor (VDR) through its nuclear receptor (NR) box motif, facilitating its nuclear translocation and initiating autophagy at the transcriptional level. To further validate these findings, an in vivo preventive model utilizing spermidine, a proven inducer of SQSTM1 was established. The results consistently demonstrated that spermidine supplementation significantly induced SQSTM1 and ameliorated ALI by mitigating airway epithelial ferroptosis. Notably, these effects were abrogated in the absence of SQSTM1. Taken together, this study identified SQSTM1 as a negative regulator of airway epithelium ferroptosis in a VDR-mediated autophagy manner, making it a potential therapeutic target for the treatment of ALI.

The long non-coding RNA mir155hg promotes NLRP3-inflammasome activation and oxidative stress response in acute lung injury by targeting miR-450b-5p to regulate HIF-1α.

BACKGROUND: Acute lung injury (ALI) can cause multiple organ dysfunction and a high mortality rate. Inflammatory responses, oxidative stress, and immune damage contribute to their pathogenic mechanisms. We studied the role of the newly discovered lncRNA, Lncmir155hg, in ALI. METHODS: The levels of Lncmir155hg and miR-450b-5p from mice with ALI were detected via polymerase chain reaction analysis (qRT-PCR) and Fluorescence in situ hybridization (FISH). Pathological changes of lung were detected by HE (hematoxylin and eosin) staining, and HIF-1α, NOD-like receptor 3 (NLRP3) and caspase-1 protein changes were detected by immunohistochemistry. MLE-12 cells proliferation was detected by Cell-Counting Kit 8 analysis, and reactive oxygen species (ROS) was detected via flow cytometry. NLRP3, apoptosis-associated speck-like protein (ASC), and caspase-1 were measured via western blotting, and enzyme-linked immunosorbent assays detected the expression of Inflammatory factors. Lncmir155hg, miR-450b-5p, miR-450b-5p, and HIF-1α targets were predicted using LncTar and miRWalk and confirmed in dual-luciferase reporter assays. RESULTS: In mice with ALI and MLE-12 cells induced by lipopolysaccharide (LPS), Lncmir155hg was high-expressed and miR-450b-5p was low-expressed. sh-Lncmir155hg reduced the damage of lung tissue, the production of inflammatory cytokines and oxidative stress reaction induced by LPS，miR-450b-5p reverses the effect of Lncmir155hg in mice. sh-Lncmir155hg decreased the protein levels of HIF-1α, NLRP3 and caspase-1 in LPS-induced lung tissues. sh-Lncmir155hg + miR-450b-5p inhibitor transfection reversed the effect of sh-Lncmir155hg on the expression of HIF-1α, NLRP3 and caspase-1. Lncmir155hg knockdown induced proliferation and inhibited NLRP3-inflammasome activation and oxidative stress in MLE-12 cells of ALI. miR-450b-5p was identified to have binding with Lncmir155hg, and inhibition of miR-450b-5p eliminated the effect of si-Lncmir155hg in MLE-12 cells of ALI. More importantly, miR-450b-5p was directly combined with HIF-1α, miR-450b-5p mimic promoted proliferation and inhibited activation of inflammasome associated proteins and reaction of oxidative stress, and HIF-1α overexpression abolished these effects. CONCLUSION: Lncmir155hg aggravated ALI via the miR-450b-5p/HIF-1α axis.

Myeloid-specific Hdac10 deletion protects against LPS-induced acute lung injury via P62 acetylation at lysine 165.

BACKGROUND: Aberrant activation of macrophages is associated with pathogenesis of acute lung injury (ALI). However, the potential pathogenesis has not been explored. OBJECTIVES: We aimed to identify whether histone deacetylase (HDAC) 10 is involved in lipopolysaccharide (LPS)-exposed ALI and reveal the underlying pathogenesis by which it promotes lung inflammation in LPS-exposed ALI via modifying P62 with deacetylation. METHODS: We constructed an ALI mice model stimulated with LPS to determine the positive effect of Hdac10 deficiency. Moreover, we cultured murine alveolar macrophage cell line (MH-S cells) and primary bone marrow-derived macrophages (BMDMs) to explore the pro-inflammatory activity and mechanism of HDAC10 after LPS challenge. RESULTS: HDAC10 expression was increased both in mice lung tissues and macrophage cell lines and promoted inflammatory cytokines production exposed to LPS. Hdac10 deficiency inhibited autophagy and inflammatory response after LPS stimulation. In vivo, Hdac10fl/fl-LysMCre mice considerably attenuated lung inflammation and inflammatory cytokines release exposed to LPS. Mechanistically, HDAC10 interacts with P62 and mediates P62 deacetylation at lysine 165 (K165), by which it promotes P62 expression and increases inflammatory cytokines production. Importantly, we identified that Salvianolic acid B (SAB), an HDAC10 inhibitor, reduces lung inflammatory response in LPS-stimulated ALI. CONCLUSION: These results uncover a previously unknown role for HDAC10 in regulating P62 deacetylation and aggravating lung inflammation in LPS-induced ALI, implicating that targeting HDAC10 is an effective therapy for LPS-exposed ALI.

Gene expression profiles to clarify the effect of low-dose benzo(a)pyrene on crystalline silica induced acute lung injury in mice.

Published evidences have suggested that air pollutant benzo(a)pyrene (BaP) may modify the toxicity and adverse effects produced by other toxicants. However, the precise role of short-term exposure to low-dose BaP on acute lung injury (ALI) induced by crystalline silica (CS) and the underlying mechanisms remain to be clarified. To investigate this issue, a mouse co-exposure model was established by intratracheal instillation of 2.5 mg CS and BaP alone or in combination. Our data found that CS exposure resulted in ALI as evidenced by lung histological changes, elevated lactate dehydrogenase activity, increased level of pro-inflammatory markers and enhanced oxidative damage. Although exposure to BaP alone had little effect on the pathological changes of mice lung tissues except for occasionally mild inflammation, it could aggravate the CS-induced ALI in a dose-dependent manner. Bioinformatic analysis of transcriptome sequencing suggested that the expression changes of significantly differentially expressed genes were closely related to the severity of ALI. The joined analysis of STC and WGCNA found that "NOD-like receptor signaling pathway", "toll-like receptor signaling pathway", "TNF signaling pathway", and "NF-kappa B signaling pathway" associated with immune and inflammatory response were the most prominent significant pathways. TLR2/9 and Nod2 might be the key inflammation-related genes that were differentially expressed in the combined lung toxicity induced by CS and BaP exposure. All these findings suggest that co-exposure of CS and low-dose BaP can cause more severe lung inflammation and oxidative damage in mice than exposure alone, which may be useful in the management and prevention of silicosis. The roles of TLR2/9 and Nod2 as candidate targets in the combined toxicity need further exploration.

METTL3-m6A methylation inhibits the proliferation and viability of type II alveolar epithelial cells in acute lung injury by enhancing the stability and translation efficiency of Pten mRNA.

BACKGROUND: The pathogenesis of acute lung injury (ALI) involves a severe inflammatory response, leading to significant morbidity and mortality. N6-methylation of adenosine (m6A), an abundant mRNA nucleotide modification, plays a crucial role in regulating mRNA metabolism and function. However, the precise impact of m6A modifications on the progression of ALI remains elusive. METHODS: ALI models were induced by either intraperitoneal injection of lipopolysaccharide (LPS) into C57BL/6 mice or the LPS-treated alveolar type II epithelial cells (AECII) in vitro. The viability and proliferation of AECII were assessed using CCK-8 and EdU assays. The whole-body plethysmography was used to record the general respiratory functions. M6A RNA methylation level of AECII after LPS insults was detected, and then the "writer" of m6A modifications was screened. Afterwards, we successfully identified the targets that underwent m6A methylation mediated by METTL3, a methyltransferase-like enzyme. Last, we evaluated the regulatory role of METTL3-medited m6A methylation at phosphatase and tensin homolog (Pten) in ALI, by assessing the proliferation, viability and inflammation of AECII. RESULTS: LPS induced marked damages in respiratory functions and cellular injuries of AECII. The m6A modification level in mRNA and the expression of METTL3, an m6A methyltransferase, exhibited a notable rise in both lung tissues of ALI mice and cultured AECII cells subjected to LPS treatment. METTL3 knockdown or inhibition improved the viability and proliferation of LPS-treated AECII, and also reduced the m6A modification level. In addition, the stability and translation of Pten mRNA were enhanced by METTL3-mediated m6A modification, and over-expression of PTEN reversed the protective effect of METTL3 knockdown in the LPS-treated AECII. CONCLUSIONS: The progression of ALI can be attributed to the elevated levels of METTL3 in AECII, as it promotes the stability and translation of Pten mRNA through m6A modification. This suggests that targeting METTL3 could offer a novel approach for treating ALI.

The m6A eraser FTO suppresses ferroptosis via mediating ACSL4 in LPS-induced macrophage inflammation.

Acute lung injury (ALI) is a serious disorder characterized by the release of pro-inflammatory cytokines and cascade activation of macrophages. Ferroptosis, a form of iron-dependent cell death triggered by intracellular phospholipid peroxidation, has been implicated as an internal mechanism underlying ALI. In this study, we investigated the effects of m6A demethylase fat mass and obesity-associated protein (FTO) on the inhibition of macrophage ferroptosis in ALI. Using a mouse model of lipopolysaccharide (LPS)-induced ALI, we observed the induction of ferroptosis and its co-localization with the macrophage marker F4/80, suggesting that ferroptosis might be induced in macrophages. Ferroptosis was promoted during LPS-induced inflammation in macrophages in vitro, and the inflammation was counteracted by the ferroptosis inhibitor ferrostatin-1 (fer-1). Given that FTO showed lower expression levels in the lung tissue of mice with ALI and inflammatory macrophages, we further dissected the regulatory capacity of FTO in ferroptosis. The results demonstrated that FTO alleviated macrophage inflammation by inhibiting ferroptosis. Mechanistically, FTO decreased the stability of ACSL4 mRNA via YTHDF1, subsequently inhibiting ferroptosis and inflammation by interrupting polyunsaturated fatty acid consumption. Moreover, FTO downregulated the synthesis and secretion of prostaglandin E2, thereby reducing ferroptosis and inflammation. In vivo, the FTO inhibitor FB23-2 aggravated lung injury, the inflammatory response, and ferroptosis in mice with ALI; however, fer-1 therapy mitigated these effects. Overall, our findings revealed that FTO may function as an inhibitor of the inflammatory response driven by ferroptosis, emphasizing its potential as a target for ALI treatment.

Regulation of YAP translocation by myeloid Pten deficiency alleviates acute lung injury via inhibition of oxidative stress and inflammation.

BACKGROUND: Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is intricately involved in modulating the inflammatory response in acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Nevertheless, the myeloid PTEN governing Hippo-YAP pathway mediated oxidative stress and inflammation in lipopolysaccharide (LPS)-induced ALI remains to be elucidate. METHODS: The floxed Pten (PtenFL/FL) and myeloid-specific Pten knockout (PtenM-KO) mice were intratracheal instill LPS (5 mg/kg) to establish ALI, then Yap siRNA mix with the mannose-conjugated polymers was used to knockdown endogenous macrophage YAP in some PtenM-KO mice before LPS challenged. The bone marrow-derived macrophages (BMMs) from PtenFL/FL and PtenM-KO mice were obtained, and BMMs were transfected with CRISPR/Cas9-mediated glycogen synthase kinase 3 Beta (GSK3ß) knockout (KO) or Yes-associated protein (YAP) KO vector subjected to LPS (100 ng/ml) challenged or then cocultured with MLE12 cells. RESULTS: Here, our findings demonstrate that myeloid-specific PTEN deficiency exerts a protective against LPS-induced oxidative stress and inflammation dysregulated in ALI model. Moreover, ablation of the PTEN-YAP axis in macrophages results in reduced nuclear factor-E2-related factor-2 (NRF2) expression, a decrease in antioxidant gene expression, augmented levels of free radicals, lipid and protein peroxidation, heightened generation of pro-inflammatory cytokines, ultimately leading to increased apoptosis in MLE12 cells. Mechanistically, it is noteworthy that the deletion of myeloid PTEN promotes YAP translocation and regulates NRF2 expression, alleviating LPS-induced ALI via the inhibition of GSK3ß and MST1 binding. CONCLUSIONS: Our study underscores the crucial role of the myeloid PTEN-YAP-NRF2 axis in governing oxidative stress and inflammation dysregulated in ALI, indicating its potential as a therapeutic target for ALI.