lncRNA NEAT1 aggravates sepsis-induced lung injury by regulating the miR-27a/PTEN axis

Neutrophil-macrophage communication via extracellular vesicle transfer promotes itaconate accumulation and ameliorates cytokine storm syndrome

Cytokine storm syndrome (CSS) is a life-threatening systemic inflammatory syndrome involving innate immune hyperactivity triggered by various therapies, infections, and autoimmune conditions. However, the potential interplay between innate immune cells is not fully understood. Here, using poly I:C and lipopolysaccharide (LPS)-induced cytokine storm models, a protective role of neutrophils through the modulation of macrophage activation was identified in a CSS model. Intravital imaging revealed neutrophil-derived extracellular vesicles (NDEVs) in the liver and spleen, which were captured by macrophages. NDEVs suppressed proinflammatory cytokine production by macrophages when cocultured in vitro or infused into CSS models. Metabolic profiling of macrophages treated with NDEV revealed elevated levels of the anti-inflammatory metabolite, itaconate, which is produced from cis-aconitate in the Krebs cycle by cis-aconitate decarboxylase (Acod1, encoded by Irg1). Irg1 in macrophages, but not in neutrophils, was critical for the NDEV-mediated anti-inflammatory effects. Mechanistically, NDEVs delivered miR-27a-3p, which suppressed the expression of Suclg1, the gene encoding the enzyme that metabolizes itaconate, thereby resulting in the accumulation of itaconate in macrophages. These findings demonstrated that neutrophil-to-macrophage communication mediated by extracellular vesicles is critical for promoting the anti-inflammatory reprogramming of macrophages in CSS and may have potential implications for the treatment of this fatal condition.

Exploring the translational landscape of the long noncoding RNA transcriptome in acute respiratory distress syndrome: it is a long way to the top

Acute respiratory distress syndrome (ARDS) poses a significant and widespread public health challenge. Extensive research conducted in recent decades has considerably improved our understanding of the disease pathophysiology. Nevertheless, ARDS continues to rank among the leading causes of mortality in intensive care units and its management remains a formidable task, primarily due to its remarkable heterogeneity. As a consequence, the syndrome is underdiagnosed, prognostication has important gaps and selection of the appropriate therapeutic approach is laborious. In recent years, the noncoding transcriptome has emerged as a new area of attention for researchers interested in biomarker development. Numerous studies have confirmed the potential of long noncoding RNAs (lncRNAs), transcripts with little or no coding information, as noninvasive tools for diagnosis, prognosis and prediction of the therapeutic response across a broad spectrum of ailments, including respiratory conditions. This article aims to provide a comprehensive overview of lncRNAs with specific emphasis on their role as biomarkers. We review current knowledge on the circulating lncRNAs as potential markers that can be used to enhance decision making in ARDS management. Additionally, we address the primary limitations and outline the steps that will be essential for integration of the use of lncRNAs in clinical laboratories. Our ultimate objective is to provide a framework for the implementation of lncRNAs in the management of ARDS.

Role of ATF3 triggering M2 macrophage polarization to protect against the inflammatory injury of sepsis through ILF3/NEAT1 axis

BACKGROUND

Sepsis is a systemic inflammatory response which is frequently associated with acute lung injury (ALI). Activating transcription factor 3 (ATF3) promotes M2 polarization, however, the biological effects of ATF3 on macrophage polarization in sepsis remain undefined.

METHODS

LPS-stimulated macrophages and a mouse model of cecal ligation and puncture (CLP)-induced sepsis were generated as in vitro and in vivo models, respectively. qRT-PCR and western blot were used to detect the expression of ATF3, ILF3, NEAT1 and other markers. The phenotypes of macrophages were monitored by flow cytometry, and cytokine secretion was measured by ELISA assay. The association between ILF3 and NEAT1 was validated by RIP and RNA pull-down assays. RNA stability assay was employed to assess NEAT1 stability. Bioinformatic analysis, luciferase reporter and ChIP assays were used to study the interaction between ATF3 and ILF3 promoter. Histological changes of lung tissues were assessed by H&E and IHC analysis. Apoptosis in lungs was monitored by TUNEL assay.

RESULTS

ATF3 was downregulated, but ILF3 and NEAT1 were upregulated in PBMCs of septic patients, as well as in LPS-stimulated RAW264.7 cells. Overexpression of ATF3 or silencing of ILF3 promoted M2 polarization of RAW264.7 cells via regulating NEAT1. Mechanistically, ILF3 was required for the stabilization of NEAT1 through direct interaction, and ATF3 was a transcriptional repressor of ILF3. ATF3 facilitated M2 polarization in LPS-stimulated macrophages and CLP-induced septic lung injury via ILF3/NEAT1 axis.

CONCLUSION

ATF3 triggers M2 macrophage polarization to protect against the inflammatory injury of sepsis through ILF3/NEAT1 axis.

NEAT1 in inflammatory infectious diseases: An integrated perspective on molecular modulation

The long non-coding RNA (lncRNA), NEAT1, has emerged as a central figure in the intricate network of molecular regulators in inflammatory infectious diseases (IIDs). The review initiates a comprehensive exploration of NEAT1's multifaceted roles and molecular interactions in the context of these complex diseases. The study begins by acknowledging the global health burden of IIDs, underscoring the urgency for innovative insights into their pathogenesis and therapeutic avenues. NEAT1 is introduced as a pivotal lncRNA with growing relevance in immune responses and inflammatory processes. The core of this review unravels the NEAT1 landscape, elucidating its involvement in the modulation of immune signalling pathways, regulation of inflammatory cytokines, and interactions with various immune cells during infection. It explores NEAT1's role in orchestrating immune responses and balancing host defence mechanisms with the risk of immunopathology. Furthermore, the review underscores the clinical significance of NEAT1 in infectious diseases, discussing its associations with disease severity, prognosis, and potential as a diagnostic and therapeutic target. It provides insights into ongoing research endeavours aimed at harnessing NEAT1 for innovative disease management strategies, including developing RNA-based therapeutics. Concluding on a forward-looking note, the review highlights the broader implications of NEAT1 in the context of emerging infectious diseases and the possibility for precision medicine approaches that leverage NEAT1's regulatory capacities. In summary, this review illuminates the pivotal role of NEAT1 in IIDs by navigating its complex landscape, offering profound insights into its implications for disease pathogenesis and the development of targeted therapies.

Signaling pathways and potential therapeutic targets in acute respiratory distress syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) is a common condition associated with critically ill patients, characterized by bilateral chest radiographical opacities with refractory hypoxemia due to noncardiogenic pulmonary edema. Despite significant advances, the mortality of ARDS remains unacceptably high, and there are still no effective targeted pharmacotherapeutic agents. With the outbreak of coronavirus disease 19 worldwide, the mortality of ARDS has increased correspondingly. Comprehending the pathophysiology and the underlying molecular mechanisms of ARDS may thus be essential to developing effective therapeutic strategies and reducing mortality. To facilitate further understanding of its pathogenesis and exploring novel therapeutics, this review provides comprehensive information of ARDS from pathophysiology to molecular mechanisms and presents targeted therapeutics. We first describe the pathogenesis and pathophysiology of ARDS that involve dysregulated inflammation, alveolar-capillary barrier dysfunction, impaired alveolar fluid clearance and oxidative stress. Next, we summarize the molecular mechanisms and signaling pathways related to the above four aspects of ARDS pathophysiology, along with the latest research progress. Finally, we discuss the emerging therapeutic strategies that show exciting promise in ARDS, including several pharmacologic therapies, microRNA-based therapies and mesenchymal stromal cell therapies, highlighting the pathophysiological basis and the influences on signal transduction pathways for their use.

Programmed cell death 4 governs NLRP3-mediated pyroptosis in septic lung disorders

INTRODUCTION

Sepsis is a pathogenic syndrome of prolonged excessive inflammation and immunosuppression produced by invading pathogens. Programmed cell death 4 (PDCD4) may be implicated in a range of inflammatory lesions, and this study aimed to confirm the involvement of PDCD4 in septic lung injury.

MATERIALS AND METHODS

Mice and bronchial epithelial 16HBE cells were separately subjected to CLP and LPS to generate in vivo and in vitro models. Following the level of PDCD4 was determined, the impacts of PDCD4 knockdown on mouse lung injury degree, inflammation, apoptosis, and pyroptosis levels were evaluated. Afterward, cells were treated with the NLRP3 agonist, and the influences of NLRP3 activation on the regulations of PDCD4 knockdown were determined.

RESULTS

PDCD4 was elevated following mice developed septic lung injury, PDCD4 knockdown ameliorated septic lung injury and reduced lung inflammation and apoptosis. Moreover, PDCD4 knockdown suppressed NLRP3-mediated pyroptosis, indicating that PDCD4 also mediated pyroptosis. According to cellular models, NLRP3 activation broke the effects of PDCD4 knockdown on cells.

CONCLUSIONS

The current study reveals that PDCD4 governs NLRP3-mediated pyroptosis in septic lung injury. PDCD4 is not only related to apoptosis and expands the knowledge of PDCD4 regulation of different cell death modes.

Role of LncRNAs in the Pathogenesis of Sepsis and their Clinical Significance

Sepsis is a fatal organ dysfunction caused by the host's uncontrolled response to infection, with high morbidity and mortality. Early diagnosis and intervention are the most effective methods to reduce the mortality due to sepsis. However, there is still a lack of definite biomarkers or intervention targets for the diagnosis, evaluation, prognosis, and treatment of sepsis. Long non-coding RNAs (lncRNAs) are a type of noncoding transcript with a length ranging from 200 to 100,000 nucleotides. LncRNAs mainly locate in the cytoplasm and nucleus and participate in various signaling pathways related to inflammatory reactions and organ dysfunction. Recent studies have reported that lncRNAs are involved in regulating the pathophysiological process of sepsis. Some classical lncRNAs have been confirmed as promising biomarkers to evaluate the severity and prognosis of sepsis. This review summarizes the mechanical studies on lncRNAs in sepsis-induced acute lung, kidney, myocardial, and liver injuries, analyzes the role of lncRNAs in the pathogenesis of sepsis, and explores the possibility of lncRNAs as potential biomarkers and intervention targets for sepsis-induced multiple organ dysfunction.

Polydatin alleviates sepsis‑induced acute lung injury via downregulation of Spi‑B

Sepsis-induced acute lung injury (ALI) is related to the dysregulation of inflammatory responses. Polydatin supplement was reported to exhibit anti-inflammatory effects in several diseases. The present study aimed to investigate the role of polydatin in sepsis-induced ALI. A cecum ligation and puncture (CLP)-induced mouse ALI model was established first and the pathological changes of lung tissues were assessed using hematoxylin and eosin staining. Meanwhile, to mimic sepsis-induced ALI in vitro, pulmonary microvascular endothelial cells (PMVECs) were treated with lipopolysaccharide (LPS). Pro-inflammatory cytokines levels were measured in lung tissues and PMVECs using ELISA. Reverse transcription-quantitative PCR was used to measure the mRNA levels of Spi-B in lung tissues and PMVECs. Moreover, the expression levels of Spi-B, p-PI3K, p-Akt, and p-NF-κB in lung tissues and PMVECs were determined using western blotting. The data revealed that polydatin attenuated CLP-induced lung injury and inhibited sepsis-induced inflammatory responses in mice. Furthermore, polydatin significantly inhibited the expression of Spi-B, p-PI3K, p-Akt, and p-NF-κB in lung tissues of mice subjected to CLP-induced ALI, while this phenomenon was reversed through Spi-B overexpression. Consistently, the anti-inflammatory effect of polydatin was abolished by Spi-B overexpression. Taken together, the current findings revealed that polydatin alleviated sepsis-induced ALI via the downregulation of Spi-B.

Hypoxic bone marrow mesenchymal stem cell-derived exosomal lncRNA XIST attenuates lipopolysaccharide-induced acute lung injury via the miR-455-3p/Claudin-4 axis

Mesenchymal stem cell-derived exosomes and long non-coding RNAs (lncRNAs) have been identified to play a role in acute lung injury (ALI). In this study, we investigated whether exosomal lncRNAs could regulate ALI and the underlying mechanisms. Bone marrow mesenchymal stem cells (BM-MSCs) were pretreated with hypoxia or normoxia, and exosomes were subsequently extracted from normoxic BM-MSCs (Nor-exos) and hypoxic BM-MSCs (Hypo-exos). A rat model of ALI was established via an airway perfusion of lipopolysaccharide (LPS). Exosomes were administered via the tail vein to evaluate the in vivo effect of exosomes in ALI. LPS-exposed RLE-6TN cells were incubated with exosomes to explore their in vitro effect in ALI. A luciferase reporter assay was used to evaluate the interaction between lncRNA XIST and miR-455-3p, as well as miR-455-3p and Claudin-4. We found that the exosomes attenuated LPS-induced ALI and Hypo-Exos exerted a greater therapeutic effect compared with Nor-exos both in vitro and in vivo. Moreover, an abundance of lncRNA XIST was observed in Hypo-exos compared with Nor-exos. Mechanistically, LncRNA XIST functioned as a miR-455-3p sponge and targeted Claudin-4 in ALI. Our results provide novel insight into the role of exosomal lncRNA XIST for the treatment of ALI. Thus, hypoxic pretreatment may represent an effective method for improving the therapeutic effects of exosomes.

Identification of potential biomarkers and pathways for sepsis using RNA sequencing technology and bioinformatic analysis

Long non-coding RNAs (lncRNAs) has been proven by many to play a crucial part in the process of sepsis. To obtain a better understanding of sepsis, the molecular biomarkers associated with it, and its possible pathogenesis, we obtained data from RNA-sequencing analysis using serum from three sepsis patients and three healthy controls (HCs). Using edgeR (one of the Bioconductor software package), we identified 1118 differentially expressed mRNAs (DEmRNAs) and 1394 differentially expressed long noncoding RNAs (DElncRNAs) between sepsis patients and HCs. We identified the biological functions of these disordered genes using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway analyses. The GO analysis showed that the homophilic cell adhesion via plasma membrane adhesion molecules was the most significantly enriched category. The KEGG signaling pathway analysis indicated that the differentially expressed genes (DEGs) were most significantly enriched in retrograde endocannabinoid signaling. Using STRING, a protein-protein interaction network was also created, and Cytohubba was used to determine the top 10 hub genes. To examine the relationship between the hub genes and sepsis, we examined three datasets relevant to sepsis that were found in the gene expression omnibus (GEO) database. PTEN and HIST2H2BE were recognized as hub gene in both GSE4607, GSE26378, and GSE9692 datasets. The receiver operating characteristic (ROC) curves indicate that PTEN and HIST2H2BE have good diagnostic value for sepsis. In conclusion, this two hub genes may be biomarkers for the early diagnosis of sepsis, our findings should deepen our understanding of the pathogenesis of sepsis.

Epigallocatechin-3-gallate ameliorates inflammatory injury caused by sepsis by regulating the lncRNA PVT1/miR-16-5p/TLR4 axis

BACKGROUND

Sepsis is identified as a severe inflammatory disease. Epigallocatechin-3-gallate (EGCG) has been reported to be a powerful anti-inflammatory chemical substance in numerous diseases. However, the underlying mechanism of the anti-inflammatory effects of EGCG in sepsis remains to be elucidated.

METHODS

The surgery for cecal ligation and puncture (CLP) was performed on male C57BL/6J mice aged 8 weeks. THP-1 cells were treated with 1 μg/ml lipopolysaccharide (LPS) for 24 h to imitate sepsis in vitro. Haematoxylene-Eosin (HE) staining of the sections of liver, lung and kidney was performed to evaluate the pathological changes. The inflammatory cytokines were quantitated by ELISA. qRT-PCR was performed to measure the expression levels of PVT1, miR-16-5p, and TLR4. The protein level of TLR4 was also assessed by Western blotting. Double luciferase reporter assay and RIP assay were performed to validate the interactions among PVT1, miR-16-5p, and TLR4.

RESULTS

EGCG inhibited the expression levels of PVT1 and TLR4 and enhanced miR-16-5p expression in CLP-operated mice and LPS-treated THP-1 cells. EGCG reduced the levels of inflammatory cytokines, which were restored by PVT1 overexpression. Mechanistically, PVT1 bound with miR-16-5p to activate TLR4 signaling. Further experiments demonstrated that miR-16-5p silencing or TLR4 overexpression antagonized sh-PVT1 or miR-16-5p mimics-mediated inhibitory effects on inflammatory cytokines, respectively. Knockdown of PVT1 alleviated inflammatory injury in CLP-induced sepsis in mice.

CONCLUSION

EGCG may effectively lower the levels of sepsis-induced inflammatory cytokines by targeting the PVT1/miR-16-5p/TLR4 axis.

The role of long noncoding RNA (lncRNA) nuclear-enriched abundant transcript 1 (NEAT1) in immune diseases

The long noncoding RNA (lncRNA) nuclear-enriched abundant transcript 1 (NEAT1) has been shown to be involved in the pathogenesis of several diseases. Herein, we discuss recent developments and insights into NEAT1 and its contribution to a variety of immune disorders. Our evaluations revealed that NEAT1's function in immune diseases seems to be focused on the modulation of paraspeckle expression and it is primarily associated with the nuclear retention of its mRNA. NEAT1 is also involved in the sequestration of paraspeckle proteins and in affecting the transcriptional expression of specific immune regulators. The expression of NEAT1 may be aberrantly upregulated in several immune pathologies, indicating that it could serve as a potential prognostic biomarker in these conditions. We summarized describing the expression changes and the role of NEAT1 in several immune diseases. We also described the mechanism of its regulation of the immune cell differentiation and function of NEAT1 in different disease.

The potentials of distinct functions of autophagy to be targeted for attenuation of myocardial ischemia/reperfusion injury in preclinical studies: an up-to-date review

Despite remarkable advances in our knowledge about the function of autophagy in myocardial ischemia/reperfusion (I/R) injury, the debate continues over whether autophagy is protective or deleterious in cardiac I/R. Due to the complexity of autophagy signaling, autophagy can play a dual role in the pathological processes of myocardial I/R injury. Thus, more researches are needed to shed light on the complex roles of autophagy in cardioprotection for the future clinical development. Such researches can lead to the finding of new therapeutic strategies for improving cardiac I/R outcomes in patients. Several preclinical studies have targeted autophagy flux as a beneficial strategy against myocardial I/R injury. In this review, we aimed to discuss the complex contribution of autophagy in myocardial I/R injury, as well as the therapeutic agents that have been shown to be useful in reducing myocardial I/R injury by targeting autophagy. For this reason, we provided an updated summary of the data from in vivo, ex vivo, and in vitro experimental studies about the therapeutic agents that exert positive effects against myocardial I/R injury by modulating autophagy flux. By addressing these valuable studies, we try to provide a motivation for the promising hypothesis of "autophagy modulation as a therapeutic strategy against cardiac I/R" in the future clinical studies.