Acute respiratory distress syndrome

Integrative Analyses of Bulk and Single-Cell RNA Seq Identified the Shared Genes in Acute Respiratory Distress Syndrome and Rheumatoid Arthritis

Acute respiratory distress syndrome (ARDS), a progressive status of acute lung injury (ALI), is primarily caused by an immune-mediated inflammatory disorder, which can be an acute pulmonary complication of rheumatoid arthritis (RA). As a chronic inflammatory disease regulated by the immune system, RA is closely associated with the occurrence and progression of respiratory diseases. However, it remains elusive whether there are shared genes between the molecular mechanisms underlying RA and ARDS. The objective of this study is to identify potential shared genes for further clinical drug discovery through integrated analysis of bulk RNA sequencing datasets obtained from the Gene Expression Omnibus database, employing differentially expressed genes (DEGs) analysis and weighted gene co-expression network analysis (WGCNA). The hub genes were identified through the intersection of common DEGs and WGCNA-derived genes. The Random Forest (RF) and least absolute shrinkage and selection operator (LASSO) algorithms were subsequently employed to identify key shared target genes associated with two diseases. Additionally, RA immune infiltration analysis and COVID-19 single-cell transcriptome analysis revealed the correlation between these key genes and immune cells. A total of 59 shared genes were identified from the intersection of DEGs and gene clusters obtained through WGCNA, which analyzed the integrated gene matrix of ALI/ARDS and RA. The RF and LASSO algorithms were employed to screen for target genes specific to ALI/ARDS and RA, respectively. The final set of overlapping genes (FCMR, ADAM28, HK3, GRB10, UBE2J1, HPSE, DDX24, BATF, and CST7) all exhibited a strong predictive effect with an area under the curve (AUC) value greater than 0.8. Then, the immune infiltration analysis revealed a strong correlation between UBE2J1 and plasma cells in RA. Furthermore, scRNA-seq analysis demonstrated differential expression of these nine target genes primarily in T cells and NK cells, with CST7 showing a significant positive correlation specifically with NK cells. Beyond that, transcriptome sequencing was conducted on lung tissue collected from ALI mice, confirming the substantial differential expression of FCMR, HK3, UBE2J1, and BATF. This study provides unprecedented evidence linking the pathophysiological mechanisms of ALI/ARDS and RA to immune regulation, which offers novel understanding for future clinical treatment and experimental research.

Tetramethylpyrazine mitigates lipopolysaccharide-induced acute lung injury by inhibiting the HMGB1/TLR4/NF-κB signaling pathway in mice

Background

Tetramethylpyrazine (TMP) possesses anti-inflammatory and antioxidant properties and plays a crucial role in mitigating acute lung injury (ALI). However, the specific underlying mechanisms remain elusive. High mobility group box 1 (HMGB1), a pro-inflammatory factor, can bind to Toll-like receptor 4 (TLR4), activating downstream signaling pathways, which in turn activate nuclear factor kappa-B (NF-κB). This study aims to explore the preventive effects of TMP on lipopolysaccharide (LPS)-induced ALI and its influence on the HMGB1/TLR4/NF-κB signaling pathway.

Methods

C57BL/6 mice were randomly divided into a control group (CON group), a model group (LPS group), a heparin (Hep) group, and a TMP group. In the model group, mice received an initial intraperitoneal injection of LPS followed by a second airway injection three hours later to induce ALI. In the TMP group, LPS was administered 30 minutes before the first intraperitoneal injection and followed by intratracheal atomization of LPS. TMP was injected intraperitoneally 30 minutes after the second LPS administration. The Hep group received heparin at 200 IU/kg following the same schedule as the TMP group. Peripheral capillary oxygen saturation (SpO2) was measured 24 hours after the initial intraperitoneal injection. Lung tissues were harvested for wet to dry weight ratio (W/D) calculation and pathological assessment via hematoxylin and eosin (HE) staining. Western blot analysis was performed to evaluate the protein levels of HMGB1, TLR4, and NF-κB p65 in lung tissues, along with the assessment of leukocyte content and protein concentration in bronchoalveolar lavage fluid (BALF).

Results

Compared to the control group, the model group showed reduced SpO2 levels, increased inflammatory indicators, and elevated expression levels of HMGB1, TLR4, and phosphorylated p65 (p-p65) proteins. TMP treatment led to a decrease in the W/D, reduced alveolar exudation, improved alveolar structure, and decreased total white blood cell count and protein concentration in BALF. Notably, the protein levels of HMGB1, TLR4, and p-p65 were significantly reduced in the TMP and Hep groups, while there were no significant differences in p65 expression among the groups.

Conclusions

TMP can alleviate LPS-induced ALI in mice by reducing lung inflammatory response through inhibiting the HMGB1/TLR4/NF-κB pathway.

Advances in Electrochemical Nitrite Reduction toward Nitric Oxide Synthesis for Biomedical Applications

Nitric oxide (NO) is an essential molecule in biomedicine, recognized for its antibacterial properties, neuronal modulation, and use in inhalation therapies. The effectiveness of NO-based treatments relies on precise control of NO concentrations tailored to specific therapeutic needs. Electrochemical generation of NO (E-NOgen) via nitrite (NO2 -) reduction offers a scalable and efficient route for controlled NO production, while also addressing environmental concerns by reducing NO2 - pollution and maintaining nitrogen cycle balance. Recent developments in catalysts and E-NOgen devices have propelled NO2 - conversion, enabling on-demand NO production. This review provides an overview of NO2 - reduction pathways, with a focus on cutting-edge Fe/Cu-based E-NOgen catalysts, and explores the development of E-NOgen devices for biomedical use. Challenges and future directions for advancing E-NOgen technologies are also discussed.

Lung-homing nanoliposomes for early intervention in NETosis and inflammation during acute lung injury

Acute lung injury (ALI) is characterized by severe inflammation in lung tissue, excessive immune response and impaired lung function. In hospitalized high-risk patients and cases of secondary infection due to surgical contamination, it can lead to higher mortality rates and require immediate intervention. Currently, clinical treatments are limited in symptomatic therapy as mechanical ventilation and corticosteroids, having insufficient efficacy in mitigating the cause of progression to severe illness. Here we report a pulmonary targeting lung-homing nanoliposome (LHN) designed to attenuate excessive Neutrophil Extracellular Trap formation (NETosis) through sivelestat and DNase-1, coupled with an anti-inflammatory effect mediated by 25-hydroxycholesterol (25-HC), offering a promising intervention for the acute phase of ALI. Through intratracheal delivery, we intend prompt and constant action within the lungs to effectively prevent excessive NETosis. Isolated neutrophils from blood samples of severe ARDS patients demonstrated significant anti-NETosis effects, as well as reduced proinflammatory cytokine secretion. Furthermore, in a murine model of LPS-induced ALI, we confirmed improvements in lung histopathology, and early respiratory function. Also, attenuation of systemic inflammatory response syndrome (SIRS), with notable reductions in NETosis and neutrophil trafficking was investigated. This presents a targeted therapeutic approach that can be applied in early stages of high-risk patients to prevent severe pulmonary disease progression.

Ambient PM2.5 orchestrates M1 polarization of alveolar macrophages via activating glutaminase 1-mediated glutaminolysis in acute lung injury

The temporary explosive growth events of atmospheric fine particulate matter (PM2.5) pollution during late autumn and winter seasons still frequently occur in China. High-concentration exposure to PM2.5 aggravates lung inflammation, leading to acute lung injury (ALI). Alveolar macrophages (AMs) participate in PM2.5-induced pulmonary inflammation and injury. The polarization of AMs is dependent on metabolic reprogramming. However, the mechanism underlying the PM2.5-induced glutaminase-mediated glutaminolysis in AM polarization is still largely obscure. In this study, we found that PM2.5-treated mice exhibited pulmonary dysfunction and inflammation. The concentrations of glutamate and succinate were increased in PM2.5-treated lungs and AMs compared with the controls, whereas glutamine and α-ketoglutarate (α-KG) levels were decreased, indicating that glutaminolysis in AMs was aberrantly activated as evidenced by increased mRNA and protein levels of GLS1 after PM2.5 exposure. Moreover, we determined that the GLS1/nuclear factor kappa-B (NF-κB)/hypoxia-inducible factor-1α (HIF-1α) pathway regulated M1 polarization of AMs upon PM2.5 exposure. Inhibition of glutaminolysis by GLS1 specific inhibitor CB-839 and GLS1 siRNA significantly decreased PM2.5-induced M1 macrophage polarization and attenuated pulmonary damage. Taken together, our findings reveal a novel mechanism by which a metabolic program regulates M1 polarization of AMs and suggest that GLS1-mediated glutaminolysis is a potential therapeutic target for treating PM2.5-induced ALI.

Inhalable and bioactive lipid-nanomedicine based on bergapten for targeted acute lung injury therapy via orchestrating macrophage polarization

Acute lung injury (ALI) or its more severe form, acute respiratory distress syndrome, is a life-threatening disease closely associated with an imbalance of M1/M2 macrophage polarization. However, current therapeutic strategies for ALI are controversial due to their side effects, restricted administration routes, or poor targeted delivery. The development of herbal medicine has uncovered numerous anti-inflammatory compounds potentially beneficial for ALI therapy. One such compound is the bergapten, a coumarin, which has been isolated from Ficus simplicissima Lour. However, it's been used as an anti-cancer drug and it's effects on ALI remain unexplored. The poor solubility and biodistribution of bergapten heavily limit its application. In this timely report, we developed a bioactive and lung-targeting lipid-nanomedicine by integrating bergapten and DPPC liposome, named as Ber-lipo. A comprehensive series of in vitro experiments confirmed the anti-inflammatory effects of Ber-lipo and its protective roles in maintaining the homeostasis of macrophage polarization and epithelial-endothelial integrity. In a lipopolysaccharide (LPS)-induced ALI mouse model, Ber-lipo can target inflamed lungs and significantly improve lung edema, tissue injury, and pulmonary function, relieve body weight loss, pulmonary permeability, and proinflammatory status, and especially maintain a balance of M1/M2 macrophage polarization. Furthermore, RNA sequencing analysis showed Ber-lipo's potential in effectively treating inflammatory lung diseases such as pneumonia, inhibiting proinflammatory signals, and altering the transcriptome of M1/M2 macrophages-associated genes in lung tissues. Molecular docking and Western blot analyses validated that Ber-lipo suppressed the activation of the TLR4/MyD88/NF-κB signaling axis responsible for ALI progression. In conclusion, this study demonstrates for the first time that new inhalable nanomedicine (Ber-lipo) can target inflamed lungs and ameliorates ALI by reprogramming macrophage polarization to an anti-inflammatory state via inactivating the TLR4/MyD88/NF-κB pathway, hence providing a promising strategy for enhanced ALI therapy in the clinic.

Electrochemical sensing of transient ascorbate fluctuation under hypoxic stress in live rat brain

Hypoxia, a common cause of programmed cell death or apoptosis, represents a neuropathological process. Although certain response proteins to hypoxic stress and their effects on cell status and fate have been identified, the real-time quantification of smaller neurochemicals to understand pathogenic mechanism in live rat brain during such stress remains unexplored. In this study, by employing a cutting-edge electrochemical tool developed with carbon nanotube-sheathed carbon fiber microelectrode that offers remarkable selectivity and temporal/spatial resolution for monitoring ascorbate, we observed a substantial efflux of ascorbate in response to hypoxic stress in live rat brain. Furthermore, using a small molecule compound as channel inhibitor to investigate the behavior of ascorbate efflux, we found that this efflux is closely correlated with N-methyl-D-aspartic acid receptor-induced neuronal excitability. Notably, antagonistic actions on volume-sensitive anion channel can suppress ascorbate efflux evoked by hypoxic stress, further revealing that ascorbate fluctuation is volume-sensitive anion channel-dependent. This research not only facilitates a greater understanding of the neurochemical mechanism in hypoxia but also uncovers a potential biomarker for future closed-loop therapies.

Exploration of key mechanisms underlying the therapeutic effects of AMD3100 on attenuating lipopolysaccharide-induced acute lung injury in mice

Context

AMD3100, a CXCR4 antagonist, has beneficial effects immaculate in the treatment of acute lung injury (ALI).

Objective

ALI is a severe inflammatory condition associated with poor prognosis and limited treatment options. AMD3100, has therapeutic effects that reduce ALI. Our study explored the regulatory mechanisms of AMD3100 in alleviating the injury of lipopolysaccharide (LPS)-induced ALI in mice.

Materials and Methods

Male ICR mice were randomly divided into control, LPS-treated, AMD3100-treated, and LPS + AMD3100-treatment groups. The histological changes of lung tissues from different groups were evaluated using hematoxylin and eosin staining. Lung injury was measured by ELISA and lung wet/dry ratio. Moreover, lung tissues from the four groups were subjected to transcriptome sequencing followed by differential expression, functional enrichment, protein-protein interaction (PPI) networks, and transcription factor analyses. The validation of mRNAs and protein levels were conducted with qRT-PCR and ELISA.

Results

Hematoxylin and eosin staining combined with the concentration of IL-1 and IL1-β and lung wet/dry ratios revealed that AMD3100 reduced the level of LPS-induced lung injury. Analysis of the transcriptome sequencing data identified 294 differentially expressed genes in the LPS-induced ALI mouse model. Based on the PPI network and module analysis, hub targets of AMD3100, such as Cxcl10 and Cxcl9, were identified in module 1, and hub targets, such as Cxcl12 and Cxcl1, were identified in module 2. Cxcl10 and Cxcl9 are involved in the Toll-like receptor signaling pathway, and Cxcl12 and Cxcl1 arae enriched in the nuclear factor-kappa B signaling pathway. Cxcl19, Cxcl10, and Cxcl1 are targeted by transcription factors like NF-κB. The validation of mRNAs and protein levels conducted by PCR and ELISA supported our transcriptome data.

Conclusions

Our findings indicate that AMD3100 may exhibit a therapeutic effect on LPS-induced ALI in mice by modulating multiple chemokines to inhibit the Toll-like receptor/nuclear factor-kappa B signaling pathway.

Fibroblast growth factor 10 alleviates LPS-induced acute lung injury by promoting recruited macrophage M2 polarization

Acute lung injury (ALI) is characterized by damage to the alveoli and an overabundance of inflammation. Representing a serious inflammatory condition, ALI lacks a precise treatment approach. Despite the recognized benefit impacts of Fibroblast growth factor-10 (FGF10) on ALI, the underlying mechanisms remain unelucidated. To study the role of FGF10 in ALI, C57BL/6 J mice were intratracheally injected with 5 mg/kg Lipopolysaccharide (LPS) with FGF10 (5 mg/kg) or an equal volume of PBS. Inflammatory factors were quantified in bronchoalveolar lavage fluid (BALF) and plasma using ELISA. RNA sequencing of F4/80+Ly6G- macrophages in BALF explored changes in macrophage phenotype and potential mechanisms. Macrophage polarization in BALF was assessed using qRT-PCR, flow cytometry, and Western blot analysis. In vitro, a Transwell co-culture of mouse lung epithelial cells (MLE12) and bone marrow macrophages (BMDM) validated the role of FGF10 in modulating LPS-induced macrophage phenotypic changes. FGF10 ameliorated LPS-induced ALI by diminishing pro-inflammatory factors (IL-1β, TNF-α, and IL-6) and the neutrophil accumulation in BALF. FGF10 also increased the levels of anti-inflammatory factor IL-10. The FGF10 intervention group exhibited enhanced gene expression of macrophage arginine biosynthesis marker (ARG1), and expression of M2-type marker CD206 in monocytes and macrophages. In addition, phosphorylated STAT3 expression increased in isolated monocyte-derived macrophages. Experiments in vitro confirmed that FGF10 could elevate macrophage M2 marker ARG1 expression through the JAK2/STAT3 pathway. FGF10 ameliorates acute LPS-induced lung injury by modulating the polarization of monocyte-derived macrophages recruited in the alveolar space to the M2 type.

Sodium propionate ameliorates lipopolysaccharide-induced acute respiratory distress syndrome in rats via the PI3K/AKT/mTOR signaling pathway

Acute respiratory distress syndrome (ARDS) is a severe lung disease characterized by significant hypoxemia, which impairs the oxygen supply necessary for optimal lung function. This study aimed to investigate the effects of sodium propionate (SP), the primary end product of intestinal flora fermentation of dietary fiber, on lipopolysaccharide (LPS)-induced ARDS in rats. The rats were treated with SP, after which the lung wet/dry ratio, arterial partial oxygen pressure (PaO2), levels of pro- and anti-inflammatory cytokines, tight junction proteins ZO-1 and Occludin, as well as LC3 and phosphorylated PI3K (p-PI3K)/p-AKT/p-mTOR protein levels, were measured. Additionally, histopathological analysis was conducted. The results indicated that SP effectively alleviated arterial hypoxemia in rats and mitigated the pathological damage to both intestinal and lung tissues caused by LPS. Notably, SP significantly reduced the levels of inflammatory factors TNF-α and IL-6 in the blood and bronchoalveolar lavage fluid (BALF) of ARDS rats, while increasing the concentration of the anti-inflammatory factor IL-10. Furthermore, SP inhibited the activation of the PI3K/AKT/mTOR signaling pathway and enhanced the LC3II/LC3I ratio in lung tissue. Therefore, SP may improve LPS-induced ARDS in rats by inhibiting the activation of the PI3K/AKT/mTOR signaling pathway, promoting autophagy, decreasing the production and release of inflammatory markers, and reducing alveolar epithelial damage.

Occludin Is Essential to Maintain Normal Alveolar Barrier Integrity and Its Protective Role During ARDS Progression

Acute respiratory distress syndrome (ARDS) is a severe lung condition without targeted therapy that is characterized by the disruption of epithelial and endothelial barriers. The role of the tight junction protein occludin in the pathogenesis of this disease is unknown, although it has previously been deemed redundant in some tissues. The aim of the present study is to determine whether occludin is required for lung function by controlling alveolar barrier integrity in mouse models. Immunofluorescence staining of lungs from ARDS patients revealed a significant decrease in occludin expression compared to controls. Gene delivery of shRNA against occludin in the mouse lung reduced occludin levels and induced lung injury, as assessed by wet-to-dry-ratio, histology, and cellularity and protein content of bronchial alveolar lavage fluid. Conversely, gene delivery of an occludin-expressing plasmid increased occludin expression and dampened endotoxin-induced lung injury. In primary rat alveolar epithelial cells, occludin levels were positively correlated with barrier integrity, as well as membrane localization of claudin-18, another tight junction protein. Collectively, our data demonstrate that occludin plays a significant role in alveolar barrier function and that targeting occludin may provide a new therapeutic approach for ARDS.

Efficacy and safety of mesenchymal stem cell therapy for acute respiratory distress syndrome-a systematic review and meta-analysis

Background

Mesenchymal stem cells (MSC) therapy for acute respiratory distress syndrome (ARDS) represents a burgeoning treatment approach, supported by numerous preclinical studies confirming its efficacy. Our study aims to provide a comprehensive evaluation of both the safety and effectiveness of MSC.

Methods

We conducted searches across three databases (PubMed, Embase, Cochrane) for randomized controlled studies up to June 23, 2024. A meta-analysis was performed on variables including adverse events, mortality, changes in the PaO2/FiO2 ratio, intensive care unit (ICU), length of stay, ventilation-free days, and changes in pro-inflammatory and anti-inflammatory cytokines. Relative risk (RR) values were employed for dichotomous variables, while mean difference (MD) and standard mean difference (SMD) were used for continuous variables. Risk bias was assessed using risk of bias 2 (ROB2).

Results

The meta-analysis encompassed 17 experiments involving 796 patients, with 410 undergoing MSC treatment and 386 in the control group. Primary outcomes indicated that MSC treatment did not escalate adverse events [RR =1.04; 95% confidence interval (CI): 0.90, 1.19; P=0.59; I2=0%]. On the contrary, it significantly diminishes the mortality (RR =0.79; 95% CI: 0.64, 0.97; P=0.02; I2=0%). Regarding secondary outcomes, MSCs led to a significant improvement in the PaO2/FiO2 ratio for ARDS patients (SMD =0.53; 95% CI: 0.15, 0.92; P=0.007; I2=0%). However, there were no significant differences in ICU length of stay (MD =-1.77; 95% CI: -6.97, 3.43; P=0.50; I2=63%) and ventilation-free days (MD =-1.29; 95% CI: -4.09, 1.51; P=0.37; I2=0%). MSCs significantly lowered C-reactive protein (CRP) (SMD =-0.65; 95% CI: -1.18, -0.13; P=0.01; I2=56%) and interleukin-6 (IL-6) levels compared to the control group (SMD =-0.76; 95% CI: -1.34, -0.17; P=0.01; I2=74%). However, changes in interleukin-10 (AIL-10) (SMD =-0.46; 95% CI: -1.51, 0.58; P=0.38; I2=77%), and changes in tumor necrosis factor-alpha (ATNF-α) (SMD =-1.5; 95% CI: -3.39, 0.40; P=0.12; I2=92%) levels showed no significant changes.

Conclusions

MSC therapy demonstrates reliable safety, with a significant impact on reducing mortality and improving certain clinical symptoms. Moreover, in certain aspects, it may alleviate the inflammatory response in ARDS. Nonetheless, these findings necessitate validation through additional high-quality randomized controlled trials.

Pyroptosis inhibition alleviates acute lung injury via E-twenty-six variant gene 5-mediated downregulation of gasdermin D

BACKGROUND

Acute lung injury (ALI) is a life-threatening condition characterized by excessive pulmonary inflammation, yet its precise pathophysiology remains elusive. Pyroptosis, a programmed cell death mechanism controlled by gasdermin D (GSDMD), has been linked to the etiology of ALI. This study investigated the regulatory functions of the transcription factor E-twenty-six variant gene 5 (ETV5) and GSDMD in ALI.

METHODS

Lipopolysaccharide (LPS) was used to treat BEAS-2B cells (50 mmol/mL) and establish an LPS-induced mouse model of ALI (by intratracheal administration, 3 mg/kg). Protein-protein docking, immunofluorescence analysis, western blotting, real-time quantitative polymerase chain reaction, and dual-luciferase reporter gene assay were used to examine ETV5-mediated negative feedback regulation of GSDMD and its effects on pyroptosis and ALI.

RESULTS

Our results showed that the physiological function of ETV5 was reduced by its downregulated expression, which impeded its nuclear translocation in ALI mice. Increased pyroptosis and enhanced production of inflammatory cytokines were associated with LPS-induced ALI. ETV5 overexpression in LPS-treated BEAS-2B cells decreased the expression of total and membrane-bound GSDMD, negatively regulated GSDMD, and prevented pyroptosis. The expression of inflammatory cytokines was subsequently reduced due to this inhibition, which, in turn, reduced ALI. Molecular docking analysis and dual-luciferase reporter gene assay results indicated a direct interaction between ETV5 and GSDMD, which inhibited GSDMD production.

CONCLUSION

Our results indicate that ETV5 inhibits pyroptosis, decreases the expression of inflammatory cytokines, and negatively regulates GSDMD expression to ameliorate ALI symptoms.

Edaravone: A Possible Treatment for Acute Lung Injury

Despite technological advances in science and medicine, acute lung injury (ALI) is still associated with high mortality rates in the ICU. Therefore, finding novel drugs and treatment approaches is crucial to preventing ALI. Drug repurposing is a common practice in clinical research, primarily for drugs that have previously received approval for use in patients, to investigate novel uses of drugs and therapies. One such medication is edaravone, which is a highly effective free-radical scavenger that also has anti-inflammatory, anti-apoptotic, antioxidant, and anti-fibrotic effects. Both basic and clinical studies have shown that edaravone can treat different types of lung injury through its distinct properties. Edaravone exhibits significant protective benefits and holds promising clinical treatment potential for ALI caused by diverse factors, thereby offering a novel approach to treating ALI. This study aims to provide new insights and treatment options for ALI by reviewing both basic and clinical research on the use of edaravone. The focus is on evaluating the effectiveness of edaravone in treating ALI caused by various factors.

Impact of time intervals on drug efficacy and phenotypic outcomes in acute respiratory distress syndrome in mice

Acute respiratory distress syndrome is a severe lung condition resulting from various causes, with life-threatening consequences that necessitate intensive care. The phenomenon can be modeled in preclinical models, notably through the use of lipopolysaccharide (LPS) instillation in mice. The phenotype induced closely recapitulates the human syndrome, including pulmonary edema, leukocyte infiltration, acute inflammation, impaired pulmonary function, and histological damage. However, the experimental designs using LPS instillations are extremely diverse in the literature. This highly complicates the interpretation of the induced phenotype chronology for future study design and hinders the proper identification of the optimal time frame to assess different readouts. Therefore, the definition of the treatment window in relation to the beginning of the disease onset also presents a significant challenge to address questions or test compound efficacy. In this context, the temporality of the different readouts usually measured in the model was evaluated in both normal and neutrophil-depleted male C57bl/6 mice using LPS-induction to assess the best window for proper readout evaluation with an optimal dynamic response range. Ventilation parameters were evaluated by whole-body plethysmography and neutrophil recruitment were evaluated in bronchoalveolar lavage fluids and in lung tissues directly. Imaging evaluation of myeloperoxidase along with activity in lung lysates and fluids were compared, along with inflammatory cytokines and lung extravasation by enzyme-linked immunoassays. Moreover, dexamethasone, the gold standard positive control in this model, was also administered at different times before and after phenotype induction to assess how kinetics affected each parameter. Overall, our data demonstrate that each readout evaluated in this study has a singular kinetic and highlights the key importance of the timing between ARDS phenotype and treatment administration and/or analysis. These findings also strongly suggest that analyzes, both in-life and post-mortem should be conducted at multiple time points to properly capture the dynamic phenotype of the LPS-ARDS model and response to treatment.

Homeobox B4 optimizes the therapeutic effect of bone marrow mesenchymal stem cells on endotoxin-associated acute lung injury in rats

BACKGROUND

Alveolar capillary endothelial cell (EC) injury has a pivotal role in driving acute respiratory distress syndrome (ARDS) progression and maintaining endothelial homeostasis. A previous ex vivo study revealed that overexpression of homeobox B4 (HOXB4) in bone marrow mesenchymal stem cells (BMSCs) enhanced protection against lipopolysaccharide (LPS)-induced EC injury by activating the Wnt/β-catenin pathway. This in vivo study was performed to verify whether BMSCs overexpressing HOXB4 exert similar protective effects on LPS-induced acute lung injury (ALI) in an animal model.

METHODS

The ALI rat model was established by intraperitoneal injection of LPS. Wildtype BMSCs or BMSCs overexpressing HOXB4 were then injected via the tail vein. The lung characteristics of rats were visualized by computed tomography. Lung histopathological characteristics and collagen deposition were assessed by hematoxylin-eosin and Masson's staining, respectively, which were combined with the lung wet/dry ratio and proinflammatory factor levels in bronchoalveolar lavage fluid to further evaluate therapeutic effects. Expression of β-catenin and VE-cadherin was assessed by western blotting and immunofluorescence.

RESULTS

Compared with wildtype BMSCs, overexpression of HOXB4 optimized the therapeutic effects of BMSCs, which manifested as improvements in lung exudation and histopathological features, reduced lung collagen deposition, amelioration of lung permeability, attenuation of lung inflammation, and enhanced expression of β-catenin and VE-cadherin proteins.

CONCLUSIONS

HOXB4-overexpressing BMSCs optimized the protective effect against LPS-induced ALI by partially activating Wnt/β-catenin signaling.

Transcription factor NF-E2-related factor 2 plays a critical role in acute lung injury/acute respiratory distress syndrome (ALI/ARDS) by regulating ferroptosis

NRF2 is an important transcription factor that regulates redox homeostasis in vivo and exerts its anti-oxidative stress and anti-inflammatory response by binding to the ARE to activate and regulate the transcription of downstream protective protein genes, reducing the release of reactive oxygen species. Ferroptosis is a novel iron-dependent, lipid peroxidation-driven cell death mode, and recent studies have shown that ferroptosis is closely associated with acute lung injury/acute respiratory distress syndrome (ALI/ARDS). NRF2 is able to regulate ferroptosis through the regulation of the transcription of its target genes to ameliorate ALI/ARDS. Therefore, This article focuses on how NRF2 plays a role in ALI/ARDS by regulating ferroptosis. We further reviewed the literature and deeply analyzed the signaling pathways related to ferroptosis which were regulated by NRF2. Additionally, we sorted out the chemical molecules targeting NRF2 that are effective for ALI/ARDS. This review provides a relevant theoretical basis for further research on this theory and the prevention and treatment of ALI/ARDS. The intended audience is clinicians and researchers in the field of respiratory disease.

The impact of positive end-expiratory pressure on right ventricular function in patients with moderate-to-severe ARDS: a prospective paired-design study

Objective

To determine the effects of varying positive end-expiratory pressures (PEEPs) on right ventricular function, hemodynamics, oxygenation, and the incidence of acute cor pulmonale (ACP) in patients with moderate-to-severe acute respiratory distress syndrome (ARDS).

Methods

This prospective paired-design study involved patients with moderate-to-severe ARDS in the ICU. Participants received lung-protective ventilation and hemodynamic monitoring. During the study, mechanical ventilation was administered with PEEPs of 5 cmH2O, 10 cmH2O, and 15 cmH2O, while maintaining an end-inspiratory plateau pressure ≤ 30 cmH2O. Various assessments, including transthoracic echocardiography, cardiac output measurement, and blood gas analysis, were conducted at baseline and after 1 h of ventilation at each PEEP. Subsequently, variations in ventilation oxygenation, echocardiographic parameters, and hemodynamic indicators under different PEEPs were analyzed to explore the potential effects of PEEP on right ventricular function and hemodynamics, as well as the incidence of ACP.

Results

A total of 317 ARDS patients were screened. Among them, 104 met the diagnostic criteria for moderate-to-severe ARDS, and 52 completed the study. The baseline PEEP of these 52 participants, acquired before commencement, was 11.5 ± 1.7 cmH2O, and the incidence of ACP was 25.0% (13/52). Intensive care unit mortality, overall hospital mortality, and 28-day mortality rates were 19.2% (10/52), 21.2% (11/52), and 32.7% (17/52), respectively. During the study, ACP incidences at PEEPs of 5 cmH2O, 10 cmH2O, and 15 cmH2O were 17.3% (9/52), 21.2% (11/52), and 38.5% (20/52), respectively. Meanwhile, the PaO2/FiO2 ratio improved with increasing PEEP, reaching 162.0 (140.9, 174.0), 171.0 (144.0, 182.0), and 176.5 (151.0, 196) mmHg at PEEPs of 5 cmH2O, 10 cmH2O, and 15 cmH2O, respectively. In addition, higher PEEPs were associated with a slight increase in PaCO2, showing statistically significant differences compared to moderate and low PEEPs. Compared to a PEEP of 5 cmH2O or 10 cmH2O, right ventricular function exhibited substantial changes at 15 cmH2O PEEP, manifested as increased pulmonary artery systolic pressure, enlarged right ventricular end-diastolic area, and decreased tricuspid annular plane systolic excursion, all with significant differences. Conversely, variations in left ventricular end-diastolic area and ejection fraction were not statistically significant. In terms of hemodynamics, increasing PEEP resulted in a decline in cardiac index (CI), with statistically significant differences between different PEEPs. Specifically, compared to the value at a PEEP of 5 cmH2O, the CI at a PEEP of 15 cmH2O decreased by 14.3% (2.63 [2.20, 2.95] vs. 3.07 [2.69, 3.67], p < 0.001). The decline in the stroke volume index with PEEP was more obvious (22.1 [18.4, 27.1] vs. 27.0 [24.2, 33.0], p < 0.001), reaching 18.1%. Additionally, both end-diastolic volume index and extravascular lung water index decreased significantly with increasing PEEP, while the pulmonary vascular permeability index remained unaffected.

Conclusion

Different PEEPs can affect the incidence of ACP in patients with moderate-to-severe ARDS. High PEEP improves oxygenation and reduces extravascular lung water without significantly affecting the pulmonary vascular permeability index and left ventricular systolic function. Nevertheless, it can cause right ventricular dilation, as well as substantial declines in right ventricular systolic function and CI, thereby causing ACP.

Association Between ACE2 and Lung Diseases

Angiotensin-converting enzyme 2 (ACE2) is an important regulator of the Renin-Angiotensin System (RAS). Additionally, it has been identified as a functional receptor for the Coronavirus. Research indicates that ACE2 plays a role in the regulation of cardiovascular systems by modulating blood pressure and electrolyte balance. Its role in pulmonary diseases has also garnered significant attention due to the widespread prevalence of Coronavirus. There is solid evidence linking ACE2 to other pulmonary diseases, including chronic obstructive pulmonary disease, acute respiratory distress syndrome, allergic asthma, among others. However, the exact pathological and physiological mechanisms of ACE2 in these diseases remain elusive. Our research aims to review and explore the latest advancements in ACE2-related studies in pulmonary diseases. These findings have the potential to open new avenues for utilizing ACE2 as a potential biomarker for early diagnosis and monitoring of pulmonary diseases.

ANALYSIS AND IDENTIFICATION OF FERROPTOSIS-RELATED GENE SIGNATURE FOR ACUTE LUNG INJURY

ABSTRACT

Background: Recent studies have shown that ferroptosis is involved in the evolution of acute lung injury (ALI), a serious respiratory pathological process leading to death. However, the regulatory mechanisms underlying ferroptosis in ALI remain largely unknown. The current study analyzed and identified a ferroptosis-related gene signature for ALI. Methods: Key genes associated with ferroptosis in ALI were identified by bioinformatics analysis. GSE104214, GSE18341, and GSE17355 datasets were downloaded from the Gene Expression Omnibus database. The signature genes were screened by least absolute shrinkage and selection operator regression, and the key genes of ALI were screened by weighted correlation network analysis (WGCNA), followed by immune infiltration analysis and functional enrichment analysis. In addition, mRNA expression of key genes in the lungs of mice with hemorrhagic shock (HS) and sepsis was verified. Results: A total of 2,132 differential genes were identified by various analyses, and 9 characteristic genes were detected using Lasso regression. We intersected nine signature genes with WGCNA module genes and finally determined four key genes ( PROK2 , IL6 , TNF , SLC7A11 ). All four key genes were closely correlated with immune cells and regulatory genes of ALI, and the expression of the four genes was significantly different in the lung tissues of HS and sepsis models. Besides, the ferroptosis-related molecules GPX4 and ACSL4 showed remarkable difference in these models. Conclusion: These results indicate that PROK2 , IL6 , TNF , and SLC7A11 may be key regulatory targets of ferroptosis during ALI. This study proved that ferroptosis is a common pathophysiological process in three ALI models.

Anti-inflammatory roles of type I interferon signaling in the lung

Excessive or persistent inflammation may have detrimental effects on lung structure and function. Currently, our understanding of conserved host mechanisms that control the inflammatory response remains incompletely understood. In this study, we investigated the role of type I interferon signaling in the inflammatory response against diverse clinically relevant stimuli. Using mice deficient in type I interferon signaling (IFNAR1-/-), we demonstrate that the absence of interferon signaling resulted in a robust and persistent inflammatory response against Pseudomonas aeruginosa, lipopolysaccharide, and chemotherapeutic agent bleomycin. The elevated inflammatory response in IFNAR1-/- mice was manifested as elevated myeloid cells, such as macrophages and neutrophils, in the bronchoalveolar lavage. The inflammatory cell response in the IFNAR1-/- mice persisted to 14 days and there is impaired recovery and fibrotic remodeling of the lung in IFNAR1-/- mice after bleomycin injury. In the Pseudomonas infection model, the elevated inflammatory cell response led to improved bacterial clearance in IFNAR1-/- mice, although there was similar lung injury and survival. We performed RNA sequencing of lung tissue in wild-type and IFNAR1-/- mice after LPS and bleomycin injury. Our unbiased analysis identified differentially expressed genes between IFNAR1-/- and wild-type mice, including previously unknown regulation of nucleotide-binding oligomerization domain (NOD)-like receptor signaling, retinoic acid-inducible gene-I (RIG-I) signaling, and necroptosis pathway by type I interferon signaling in both models. These data provide novel insights into the conserved anti-inflammatory mechanisms of the type I interferon signaling.NEW & NOTEWORTHY Type I interferons are known for their antiviral activities. In this study, we demonstrate a conserved anti-inflammatory role of type I interferon signaling against diverse stimuli in the lung. We show that exacerbated inflammatory response in the absence of type I interferon signaling has both acute and chronic consequences in the lung including structural changes.

Consensus statements on the utility of defining ARDS and the utility of past and current definitions of ARDS-protocol for a Delphi study

INTRODUCTION

Acute respiratory distress syndrome (ARDS), marked by acute hypoxemia and bilateral pulmonary infiltrates, has been defined in multiple ways since its first description. This Delphi study aims to collect global opinions on the conceptual framework of ARDS, assess the usefulness of components within current and past definitions and investigate the role of subphenotyping. The varied expertise of the panel will provide valuable insights for refining future ARDS definitions and improving clinical management.

METHODS

A diverse panel of 35-40 experts will be selected based on predefined criteria. Multiple choice questions (MCQs) or 7-point Likert-scale statements will be used in the iterative Delphi rounds to achieve consensus on key aspects related to the utility of definitions and subphenotyping. The Delphi rounds will be continued until a stable agreement or disagreement is achieved for all statements.

ANALYSIS

Consensus will be considered as reached when a choice in MCQs or Likert-scale statement achieved ≥80% of votes for agreement or disagreement. The stability will be checked by non-parametric χ2 tests or Kruskal Wallis test starting from the second round of Delphi process. A p-value ≥0.05 will be used to define stability.

ETHICS AND DISSEMINATION

The study will be conducted in full concordance with the principles of the Declaration of Helsinki and will be reported according to CREDES guidance. This study has been granted an ethical approval waiver by the NMC Healthcare Regional Research Ethics Committee, Dubai (NMCHC/CR/DXB/REC/APP/002), owing to the nature of the research. Informed consent will be obtained from all panellists before the start of the Delphi process. The study will be published in a peer-review journal with the authorship agreed as per ICMJE requirements.

TRIAL REGISTRATION NUMBER

NCT06159465.

Garlic oil supplementation blocks inflammatory pyroptosis-related acute lung injury by suppressing the NF-κB/NLRP3 signaling pathway via H2S generation

Acute lung injury (ALI) is a major cause of acute respiratory failure with a high morbidity and mortality rate, and effective therapeutic strategies for ALI remain limited. Inflammatory response is considered crucial for the pathogenesis of ALI. Garlic, a globally used cooking spice, reportedly exhibits excellent anti-inflammatory bioactivity. However, protective effects of garlic against ALI have never been reported. This study aimed to investigate the protective effects of garlic oil (GO) supplementation on lipopolysaccharide (LPS)-induced ALI models. Hematoxylin and eosin staining, pathology scores, lung myeloperoxidase (MPO) activity measurement, lung wet/dry (W/D) ratio detection, and bronchoalveolar lavage fluid (BALF) analysis were performed to investigate ALI histopathology. Real-time polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay were conducted to evaluate the expression levels of inflammatory factors, nuclear factor-κB (NF-κB), NLRP3, pyroptosis-related proteins, and H2S-producing enzymes. GO attenuated LPS-induced pulmonary pathological changes, lung W/D ratio, MPO activity, and inflammatory cytokines in the lungs and BALF. Additionally, GO suppressed LPS-induced NF-κB activation, NLRP3 inflammasome expression, and inflammatory-related pyroptosis. Mechanistically, GO promoted increased H2S production in lung tissues by enhancing the conversion of GO-rich polysulfide compounds or by increasing the expression of H2S-producing enzymes in vivo. Inhibition of endogenous or exogenous H2S production reversed the protective effects of GO on ALI and eliminated the inhibitory effects of GO on NF-κB, NLRP3, and pyroptotic signaling pathways. Overall, these findings indicate that GO has a critical anti-inflammatory effect and protects against LPS-induced ALI by suppressing the NF-κB/NLRP3 signaling pathway via H2S generation.

Guben Qingfei decoction attenuates LPS-induced acute lung injury by modulating the TLR4/NF-κB and Keap1/Nrf2 signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Acute lung injury (ALI) is a life-threatening and widespread disease, with exceptionally high morbidity and mortality rates. Unfortunately, effective drugs for ALI treatment are currently lacking. Guben Qingfei decoction (GBQF) is a Chinese herbal compound known for its efficacy in treating viral pneumonia, yet the precise underlying mechanisms remain unknown.

AIM OF THE STUDY

This study aimed to validate the mitigating effect of GBQF on ALI and to further investigate its mechanism.

MATERIALS AND METHODS

An ALI mice model was established by infusing LPS into the endotracheal tube. The effects of GBQF on ALI were investigated by measuring lung W/D; MPO; BALF total protein concentration; total number of cells; TNF-α, IL-1β, and IL-6 levels; pathological changes in lung tissue, and oxidation products. Immunohistochemistry and Western Blotting were performed to verify the underlying mechanisms. MH-S and BEAS-2B cells were induced by LPS, and the effects of GBQF were confirmed by RT-PCR and immunofluorescence.

RESULTS

GBQF significantly reduced LPS-induced ALI in mice, improved lung inflammation, reduced the production of oxidative products, increased the activity of antioxidant enzymes, and reduced the degree of lung tissue damage. GBQF prevents MH-S cells from releasing inflammatory factors and reduces oxidative damage to BEAS-2B cells. In vivo studies have delved deeper into the mechanism of action of GBQF, revealing its correlation with the TLR4/NF-κB and Keap1/Nrf2 pathways.

CONCLUSIONS

Our study demonstrates that GBQF is an effective treatment for ALI, providing a new perspective on medication development for ALI treatment.

Repurposing Disulfiram to Combat Acute Respiratory Distress Syndrome with Targeted Delivery by LET-Functionalized Nanoplatforms

Acute respiratory distress syndrome (ARDS) is a serious respiratory condition characterized by a damaged pulmonary endothelial barrier that causes protein-rich lung edema, an influx of proinflammatory cells, and treatment-resistant hypoxemia. Damage to pulmonary endothelial cells and inflammation are pivotal in ARDS development with a key role played by endothelial cell pyroptosis. Disulfiram (DSF), a drug that has long been used to treat alcohol addiction, has recently been identified as a potent inhibitor of gasdermin D (GSDMD)-induced pore formation and can thus prevent pyroptosis and inflammatory cytokine release. These findings indicate that DSF is a promising treatment for inflammatory disorders. However, addressing the challenge posed by its intrinsic physicochemical properties, which hinder intravenous administration, and effective delivery to pulmonary vascular endothelial cells are crucial. Herein, we used biocompatible liposomes incorporating a lung endothelial cell-targeted peptide (CGSPGWVRC) to produce DSF-loaded nanoparticles (DTP-LET@DSF NPs) for targeted delivery and reactive oxygen species-responsive release facilitated by the inclusion of thioketal (TK) within the liposomal structure. After intravenous administration, DTP-LET@DSF NPs exhibited excellent cytocompatibility and minor systemic toxicity, effectively inhibited pyroptosis, mitigated lipopolysaccharide (LPS)-induced ARDS, and prevented cytokine storms resulting from excessive immune reactions in ARDS mice. This study presents a straightforward nanoplatform for ARDS treatment that potentially paves the way for the clinical use of this nanomedicine.

Quantitative CT Texture Analysis of COVID-19 Hospitalized Patients during 3-24-Month Follow-Up and Correlation with Functional Parameters

BACKGROUND

To quantitatively evaluate CT lung abnormalities in COVID-19 survivors from the acute phase to 24-month follow-up. Quantitative CT features as predictors of abnormalities' persistence were investigated.

METHODS

Patients who survived COVID-19 were retrospectively enrolled and underwent a chest CT at baseline (T0) and 3 months (T3) after discharge, with pulmonary function tests (PFTs). Patients with residual CT abnormalities repeated the CT at 12 (T12) and 24 (T24) months after discharge. A machine-learning-based software, CALIPER, calculated the CT percentage of the whole lung of normal parenchyma, ground glass (GG), reticulation (Ret), and vascular-related structures (VRSs). Differences (Δ) were calculated between time points. Receiver operating characteristic (ROC) curve analyses were performed to test the baseline parameters as predictors of functional impairment at T3 and of the persistence of CT abnormalities at T12.

RESULTS

The cohort included 128 patients at T0, 133 at T3, 61 at T12, and 34 at T24. The GG medians were 8.44%, 0.14%, 0.13% and 0.12% at T0, T3, T12 and T24. The Ret medians were 2.79% at T0 and 0.14% at the following time points. All Δ significantly differed from 0, except between T12 and T24. The GG and VRSs at T0 achieved AUCs of 0.73 as predictors of functional impairment, and area under the curves (AUCs) of 0.71 and 0.72 for the persistence of CT abnormalities at T12.

CONCLUSIONS

CALIPER accurately quantified the CT changes up to the 24-month follow-up. Resolution mostly occurred at T3, and Ret persisting at T12 was almost unchanged at T24. The baseline parameters were good predictors of functional impairment at T3 and of abnormalities' persistence at T12.

Elevated ferritin, mediated by IL-18 is associated with systemic inflammation and mortality in acute respiratory distress syndrome (ARDS)

BACKGROUND

Inflammatory subphenotypes have been identified in acute respiratory distress syndrome (ARDS). Hyperferritinaemia in sepsis is associated with hyperinflammation, worse clinical outcomes, and may predict benefit with immunomodulation. Our aim was to determine if raised ferritin identified a subphenotype in patients with ARDS.

METHODS

Baseline plasma ferritin concentrations were measured in patients with ARDS from two randomised controlled trials of simvastatin (Hydroxymethylglutaryl-CoA Reductase Inhibition with Simvastatin in Acute Lung Injury to Reduce Pulmonary Dysfunction-2 (HARP-2); discovery cohort, UK) and neuromuscular blockade (ROSE; validation cohort, USA). Results were analysed using a logistic regression model with restricted cubic splines, to determine the ferritin threshold associated with 28-day mortality.

RESULTS

Ferritin was measured in 511 patients from HARP-2 (95% of patients enrolled) and 847 patients (84% of patients enrolled) from ROSE. Ferritin was consistently associated with 28-day mortality in both studies and following a meta-analysis, a log-fold increase in ferritin was associated with an OR 1.71 (95% CI 1.01 to 2.90) for 28-day mortality. Patients with ferritin >1380 ng/mL (HARP-2 28%, ROSE 24%) had a significantly higher 28-day mortality and fewer ventilator-free days in both studies. Mediation analysis, including confounders (acute physiology and chronic health evaluation-II score and ARDS aetiology) demonstrated a statistically significant contribution of interleukin (IL)-18 as an intermediate pathway between ferritin and mortality.

CONCLUSIONS

Ferritin is a clinically useful biomarker in ARDS and is associated with worse patient outcomes. These results provide support for prospective interventional trials of immunomodulatory agents targeting IL-18 in this hyperferritinaemic subgroup of patients with ARDS.

The link between neutrophils, NETs, and NLRP3 inflammasomes: The dual effect of CD177 and its therapeutic potential in acute respiratory distress syndrome/acute lung injury

Neutrophils are important inflammatory effector cells that protect against foreign invasion but also cause self-harm. Numerous neutrophils infiltrate the lungs in acute respiratory distress syndrome/acute lung injury (ARDS/ALI) patients. However, the exact impact of neutrophil infiltration on ARDS's onset and progression remains unclear. To investigate this, we analyzed two ARDS-related datasets from the Gene Expression Omnibus public database and discovered an association between CD177, a neutrophil-specific surface protein, and ARDS progression. We used quantitative flow cytometry to assess CD177+ neutrophils in the peripheral blood of clinical ARDS patients vs healthy controls, finding a significant increase in CD177+ neutrophils percentage among total neutrophils in ARDS patients. This finding was further confirmed in ALI mouse models. Subsequent animal experiments showed that anti-CD177 effectively reduces pulmonary edema, neutrophil infiltration, and inflammatory cytokine release, along with a decrease in reactive oxygen species (ROS) and myeloperoxidase (MPO) levels. We also established an in vitro co-culture system to mimic neutrophil and lung epithelial cell interactions. In the anti-CD177 group, we observed decreased expression of NLRP3, caspase 1, peptidyl arginine deiminase (PAD4), MPO, and ROS, along with a reduction in certain inflammatory cytokines. These results indicate a crucial role for the CD177 gene in ARDS's development and progression. Inhibiting CD177 may help mitigate excessive activation of NLRP3 inflammasomes, ROS, and neutrophil extracellular traps (NETs), thus alleviating ARDS.

Hospital mortality rate and predictors in acute pancreatitis in Poland: A single-center experience

BACKGROUND

Despite advances in medicine, acute pancreatitis remains a disorder that is associated with a high mortality rate. The objective of this study was to analyze in-hospital mortality in patients hospitalized with acute pancreatitis.

METHODS

A prospective analysis of patients hospitalized with acute pancreatitis in a single surgical center was performed. Etiological factors, concomitant diseases, age, and intensive care unit treatment status were assessed to determine their impact on the cause and time of patient death. In addition, conventional laboratory tests performed in the emergency ward were evaluated for their potential as predictors of mortality.

RESULTS

The study included 476 (n) patients hospitalized with acute pancreatitis in a single surgical center. The presentations included mild disease in 261 (54.8%) patients, moderate disease in 132 (27.7%) patients, and severe disease in 83 (17.5%) patients. The overall mortality rate was 7.14% (n = 34), including 41% in the severe disease group. The mean and median hospitalization times for these patients were 13.9 and 7 days, respectively. Respiratory failure is the main cause of patient death.

CONCLUSIONS

Acute pancreatitis remains one of the most common gastroenterological diseases that may lead to death. Acute pancreatitis-related respiratory failure is the most common cause of death among patients with alcohol etiology of the disease. Moreover, the mortality rate was higher among older patients. Therefore, actions should be taken to discover prognostic factors of the severe form and initiate appropriate treatment.

Prognostic performance of the Age, PaO2/FiO2 Ratio, and Plateau Pressure Score (APPS) for mortality in patients with COVID-19-associated acute respiratory distress syndrome admitted to an intensive care unit

Background

A predictive scoring system used in patients with acute respiratory distress syndrome (ARDS) known as Age, PaO2/FiO2, Plateau Pressure Score (APPS) has been externally validated to predict mortality in Asian and Caucasian populations. Its performance in Latin American and COVID-19 patients still needs to be done.

Objective

To assess the association between APPS and mortality, as well as APPS performance in predicting mortality within 28 days of intensive care unit (ICU) admission in patients with ARDS due to COVID-19.

Design

Analytical observational retrospective cohort study.

Methods

We conducted a retrospective cohort study in patients diagnosed with ARDS according to the Berlin criteria who were admitted to the ICU. We evaluated the prognostic performance of APPS using the area under the receiver operating characteristic curve (AUC-ROC), and association with mortality was measured using the Cox proportional hazards regression models.

Results

A total of 271 patients were analyzed. The AUC for 28-day mortality was 0.78 (95% CI: 0.73-0.84). In the Cox proportional hazards model, after adjusting for sex and categorized Charlson Comorbidity Index, it was found that grade 2 APPS (aHR: 3.67, 95% CI: 2.14-6.30, p < 0.001) and grade 3 APPS (aHR: 7.95, 95% CI: 3.72-17.02, p < 0.001) were associated with a higher hazard of 28-day mortality.

Conclusion

The APPS scoring system has a good prognostic performance for mortality in patients diagnosed with COVID-19-induced ARDS.

Role of gut microbes in acute lung injury/acute respiratory distress syndrome

Acute lung injury (ALI) is an acute, diffuse inflammatory lung condition triggered by factors of severe infections, trauma, shock, burns, ischemia-reperfusion, and mechanical ventilation. It is primarily characterized by refractory hypoxemia and respiratory distress. The more severe form, acute respiratory distress syndrome (ARDS), can progress to multi-organ failure and has a high mortality rate. Despite extensive research, the exact pathogenesis of ALI and ARDS remains complex and not fully understood. Recent advancements in studying the gut microecology of patients have revealed the critical role that gut microbes play in ALI/ARDS onset and progression. While the exact mechanisms are still under investigation, evidence increasingly points to the influence of gut microbes and their metabolites on ALI/ARDS. This review aims to summarize the role of gut microbes and their metabolites in ALI/ARDS caused by various triggers. Moreover, it explores potential mechanisms and discusses how gut microbe-targeting interventions might offer new clinical strategies for the treatment of ALI/ARDS.

A combination of oxygenation and driving pressure can provide valuable information in predicting the risk of mortality in ARDS patients

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a common life-threatening condition in critically ill patients. Itis also an important public health issue because it can cause substantial mortality and health care burden worldwide. The objective of this study was to investigate therisk factors that impact ARDS mortality in a medical center in Taiwan.

METHODS

This was a single center, observational study thatretrospectively analyzed data from adults in 6 intensive care units (ICUs) at Taichung Veterans General Hospital in Taiwan from 1st October, 2018to30th September, 2019. Patients needing invasive mechanical ventilation and meeting the Berlin definition criteria were included for analysis.

RESULTS

A total of 1,778 subjects were screened in 6 adult ICUs and 370 patients fulfilled the criteria of ARDS in the first 24 hours of the ICU admission. Among these patients, the prevalenceof ARDS was 20.8% and the overall hospital mortality rate was 42.2%. The mortality rates of mild, moderate and severe ARDS were 35.9%, 43.9% and 46.5%, respectively. In a multivariate logistic regression model, combination of driving pressure (DP) > 14cmH2O and oxygenation (P/F ratio)≤150 was an independent predictor of mortality (OR2.497, 95% CI 1.201-5.191, p = 0.014). Patients with worse oxygenation and a higher driving pressure had the highest hospital mortality rate(p<0.0001).

CONCLUSIONS

ARDS is common in ICUs and the mortality rate remains high. Combining oxygenation and respiratory mechanics may better predict the outcomes of these ARDS patients.

Mesenchymal stem cells ameliorate H9N2-induced acute lung injury by inhibiting caspase-3-GSDME-mediated pyroptosis of lung alveolar epithelial cells

Influenza A virus infection mediates the host's excessive immune response, wherein caspase-3-GSDME-mediated pyroptosis of lung alveolar epithelial cells can contribute to inducing cytokine storm, leading to acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). Numerous studies have shown that mesenchymal stem cells (MSCs) possess potent immunomodulatory abilities and can mitigate virus-induced cytokine storm and lung injury. However, the role of MSCs in lung pyroptosis remains poorly understood. In this study, we established an ALI model using a mouse-adapted strain of avian influenza virus H9N2 (MA01) and intervened by injecting appropriate bone marrow-derived mesenchymal stem cells (BMMSCs) into the mouse's trachea. The results obtained from animal experiments demonstrated that BMMSCs prevented and ameliorated ALI by inhibiting Caspase-3-GSDME-mediated pyroptosis of lung epithelial cells as well as hypercytokinemia. Similarly, corresponding results were observed in vitro, where BMMSCs and the lung epithelial cell line MLE-12 cells were co-cultured in a transwell compartment. Additionally, the caspase-3 inhibitor Z-DEVD-FMK could block MA01-induced GSDME activation. Furthermore, by combining RNA-Seq data with in vitro and in vivo results, we also discovered that MA01-induced pyroptosis is associated with the BAK/BAX-dependent mitochondrial apoptosis pathway. Notably, BMMSCs exhibit the ability to interfere with this signaling pathway. In conclusion, this study provides novel theoretical support for the utilization of BMMSCs in the treatment of ALI induced by influenza.

Genetically Engineered Cellular Nanovesicle as Targeted DNase I Delivery System for the Clearance of Neutrophil Extracellular Traps in Acute Lung Injury

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) are prevalent critical illnesses with a high mortality rate among patients in intensive care units. Neutrophil extracellular traps (NETs) are implicated in the pathogenesis of ALI/ARDS and represent a promising therapeutic target. However, the clinical application of deoxyribonuclease I (DNase I), the only drug currently available to clear NETs, is limited due to the lack of precise and efficient delivery strategies. Therefore, targeted delivery of DNase I to the inflamed lung remains a critical issue to be addressed. Herein, a novel biomimetic DNase I delivery system is developed (DCNV) that employs genetically and bioorthogonally engineered cellular nanovesicles for pulmonary NETs clearance. The CXC motif chemokine receptor 2 overexpressed cellular nanovesicles can mimic the inflammatory chemotaxis of neutrophils in ALI/ARDS, leading to enhanced lung accumulation. Furthermore, DNase I immobilized through bioorthogonal chemistry exhibits remarkable enzymatic activity in NETs degradation, thus restraining inflammation and safeguarding lung tissue in the lipopolysaccharide-induced ALI murine model. Collectively, the findings present a groundbreaking proof-of-concept in the utilization of biomimetic cellular nanovesicles to deliver DNase I for treating ALI/ARDS. This innovative strategy may usher in a new era in the development of pharmacological interventions for various inflammation-related diseases.

Octane in exhaled breath to diagnose acute respiratory distress syndrome in invasively ventilated intensive care unit patients

Background

The concentration of exhaled octane has been postulated as a reliable biomarker for acute respiratory distress syndrome (ARDS) using metabolomics analysis with gas chromatography and mass spectrometry (GC-MS). A point-of-care (POC) breath test was developed in recent years to accurately measure octane at the bedside. The aim of the present study was to validate the diagnostic accuracy of exhaled octane for ARDS using a POC breath test in invasively ventilated intensive care unit (ICU) patients.

Methods

This was an observational cohort study of consecutive patients receiving invasive ventilation for at least 24 h, recruited in two university ICUs. GC-MS and POC breath tests were used to quantify the exhaled octane concentration. ARDS was assessed by three experts following the Berlin definition and used as the reference standard. The area under the receiver operating characteristic curve (AUC) was used to assess diagnostic accuracy.

Results

519 patients were included and 190 (37%) fulfilled the criteria for ARDS. The median (interquartile range) concentration of octane using the POC breath test was not significantly different between patients with ARDS (0.14 (0.05-0.37) ppb) and without ARDS (0.11 (0.06-0.26) ppb; p=0.64). The AUC for ARDS based on the octane concentration in exhaled breath using the POC breath test was 0.52 (95% CI 0.46-0.57). Analysis of exhaled octane with GC-MS showed similar results.

Conclusions

Octane in exhaled breath has insufficient diagnostic accuracy for ARDS. This disqualifies the use of octane as a biomarker in the diagnosis of ARDS and challenges most of the research performed up to now in the field of exhaled breath metabolomics.

CircRNAs in BALF exosomes and plasma as diagnostic biomarkers in patients with acute respiratory distress syndrome caused by severe pneumonia

Background

The transcriptomic studies targeting circular RNAs (circRNAs) in bronchoalveolar lavage fluid (BALF) exosomes of acute respiratory distress syndrome (ARDS) patients caused by severe pneumonia have rarely been reported. This study aimed to screen and validate abnormally expressed circRNAs in exosomes from BALF of patients with ARDS caused by severe pneumonia and then evaluate the diagnostic values of these circRNAs for ARDS.

Method

BALF was collected from four patients with ARDS caused by severe pneumonia and four healthy subjects. CircRNA expression profile was obtained by microarray analysis in BALF exosomes of the discovery cohort. The differentially expressed circRNAs in BALF exosomes were verified by real-time quantitative PCR (RT-qPCR) and underwent competitive endogenous RNA (ceRNA) network construction and functional enrichment analysis.

Results

A total of 629 circRNAs were differentially expressed in BALF exosomes between ARDS patients and healthy subjects. Nine differentially expressed circRNAs were validated by RT-qPCR, and seven were consistent with the results of microarray analysis. CeRNA network analysis was performed for hsa_circRNA_002809, hsa_circRNA_042882, and hsa_circRNA_104034. Functional enrichment analysis showed that the target genes were mainly associated with hypoxia-induced damage, inflammatory response, and the HIF-1 signaling pathway. Hsa_circRNA_042882 and hsa_circRNA_104034 can be regarded as promising diagnostic biomarkers for patients with ARDS caused by severe pneumonia, with remarkable sensitivity and specificity of the area under the curve of 0.8050 and 1 or 0.835 and 0.799, respectively.

Conclusion

This study obtained circRNA expression profiles of ARDS patients, and hsa_circRNA_042882 and hsa_circRNA_104034 were regarded as promising diagnostic biomarkers for patients with ARDS caused by severe pneumonia.

Skin Gene Expression Profiles in Systemic Sclerosis: From Clinical Stratification to Precision Medicine

Systemic sclerosis, also known as scleroderma or SSc, is a condition characterized by significant heterogeneity in clinical presentation, disease progression, and response to treatment. Consequently, the design of clinical trials to successfully identify effective therapeutic interventions poses a major challenge. Recent advancements in skin molecular profiling technologies and stratification techniques have enabled the identification of patient subgroups that may be relevant for personalized treatment approaches. This narrative review aims at providing an overview of the current status of skin gene expression analysis using computational biology approaches and highlights the benefits of stratifying patients upon their skin gene signatures. Such stratification has the potential to lead toward a precision medicine approach in the management of SSc.

Impact of Pneumonia on Cognitive Aging: A Longitudinal Propensity-Matched Cohort Study

BACKGROUND

Acute clinical events, such as pneumonia, may impact physical functionality but their effect on cognition and the possible duration of this effect remains to be quantified. This study investigated the impact of pneumonia on cognitive trajectories and dementia development in older people.

METHODS

Data were obtained from 60+ years old individuals, who were assessed from 2001 to 2018 in the population-based SNAC-K study (Sweden). Participants were eligible if they were not institutionalized, had no dementia, and did not experience pneumonia 5 years prior to baseline (N = 2 063). A propensity score was derived to match 1:3 participants hospitalized with a diagnosis of pneumonia (N = 178), to nonexposed participants (N = 534). Mixed linear models were used to model cognitive decline. The hazard of dementia, clinically diagnosed by physicians following Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV, was estimated using Cox regression models.

RESULTS

We found a transient impact of pneumonia on cognitive decline in the first 2.5 years (B = -0.94, 95% confidence interval [CI] -1.75, -0.15). The hazard ratio (HR) for dementia was not statistically significantly increased in pneumonia participants (HR = 1.17, 95%CI 0.82, 1.66).

CONCLUSIONS

The transient impact of pneumonia on cognitive function suggests an increased need of health care for patients after a pneumonia-related hospitalization and reinforces the relevance of pneumonia prevention.

Molecular and immune signatures, and pathological trajectories of fatal COVID-19 lungs defined by in situ spatial single-cell transcriptome analysis

Despite intensive studies during the last 3 years, the pathology and underlying molecular mechanism of coronavirus disease 2019 (COVID-19) remain poorly defined. In this study, we investigated the spatial single-cell molecular and cellular features of postmortem COVID-19 lung tissues using in situ sequencing (ISS). We detected 10 414 863 transcripts of 221 genes in whole-slide tissues and segmented them into 1 719 459 cells that were mapped to 18 major parenchymal and immune cell types, all of which were infected by SARS-CoV-2. Compared with the non-COVID-19 control, COVID-19 lungs exhibited reduced alveolar cells (ACs) and increased innate and adaptive immune cells. We also identified 19 differentially expressed genes in both infected and uninfected cells across the tissues, which reflected the altered cellular compositions. Spatial analysis of local infection rates revealed regions with high infection rates that were correlated with high cell densities (HIHD). The HIHD regions expressed high levels of SARS-CoV-2 entry-related factors including ACE2, FURIN, TMPRSS2 and NRP1, and co-localized with organizing pneumonia (OP) and lymphocytic and immune infiltration, which exhibited increased ACs and fibroblasts but decreased vascular endothelial cells and epithelial cells, mirroring the tissue damage and wound healing processes. Sparse nonnegative matrix factorization (SNMF) analysis of niche features identified seven signatures that captured structure and immune niches in COVID-19 tissues. Trajectory inference based on immune niche signatures defined two pathological routes. Trajectory A primarily progressed with increased NK cells and granulocytes, likely reflecting the complication of microbial infections. Trajectory B was marked by increased HIHD and OP, possibly accounting for the increased immune infiltration. The OP regions were marked by high numbers of fibroblasts expressing extremely high levels of COL1A1 and COL1A2. Examination of single-cell RNA-seq data (scRNA-seq) from COVID-19 lung tissues and idiopathic pulmonary fibrosis (IPF) identified similar cell populations consisting mainly of myofibroblasts. Immunofluorescence staining revealed the activation of IL6-STAT3 and TGF-β-SMAD2/3 pathways in these cells, likely mediating the upregulation of COL1A1 and COL1A2 and excessive fibrosis in the lung tissues. Together, this study provides a spatial single-cell atlas of cellular and molecular signatures of fatal COVID-19 lungs, which reveals the complex spatial cellular heterogeneity, organization, and interactions that characterized the COVID-19 lung pathology.

Circulatory HMGB1 is an early predictive and prognostic biomarker of ARDS and mortality in a swine model of polytrauma

Acute respiratory distress syndrome (ARDS) is a leading cause of morbidity and mortality in polytrauma patients. Pharmacological treatments of ARDS are lacking, and ARDS patients rely on supportive care. Accurate diagnosis of ARDS is vital for early intervention and improved outcomes but is presently delayed up to days. The use of biomarkers for early identification of ARDS development is a potential solution. Inflammatory mediators high-mobility group box 1 (HMGB1), syndecan-1 (SDC-1), and C3a have been previously proposed as potential biomarkers. For this study, we analyzed these biomarkers in animals undergoing smoke inhalation and 40% total body surface area burns, followed by intensive care for 72 h post-injury (PI) to determine their association with ARDS and mortality. We found that the levels of inflammatory mediators in serum were affected, as well as the degree of HMGB1 and Toll-like receptor 4 (TLR4) signal activation in the lung. The results showed significantly increased HMGB1 expression levels in animals that developed ARDS compared with those that did not. Receiver operating characteristic (ROC) analysis showed that HMGB1 levels at 6 h PI were significantly associated with ARDS development (AUROC=0.77) and mortality (AUROC=0.82). Logistic regression analysis revealed that levels of HMGB1 ≥24.10 ng/ml are associated with a 13-fold higher incidence of ARDS [OR:13.57 (2.76-104.3)], whereas the levels of HMGB1 ≥31.39 ng/ml are associated with a 12-fold increase in mortality [OR: 12.00 (2.36-93.47)]. In addition, we found that mesenchymal stem cell (MSC) therapeutic treatment led to a significant decrease in systemic HMGB1 elevation but failed to block SDC-1 and C3a increases. Immunohistochemistry analyses showed that smoke inhalation and burn injury induced the expression of HMGB1 and TLR4 and stimulated co-localization of HMGB1 and TLR4 in the lung. Interestingly, MSC treatment reduced the presence of HMGB1, TLR4, and the HMGB1-TLR4 co-localization. These results show that serum HMGB1 is a prognostic biomarker for predicting the incidence of ARDS and mortality in swine with smoke inhalation and burn injury. Therapeutically blocking HMGB1 signal activation might be an effective approach for attenuating ARDS development in combat casualties or civilian patients.

Signaling Pathways in Inflammation and Its Resolution: New Insights and Therapeutic Challenges

Tissue inflammation is a dynamic process that develops step by step, in response to an injury, to preserve tissue integrity [...].

The association between early fluid strategy and prognosis of acute respiratory distress syndrome: A post hoc study of CHARDS

We aimed to assess general fluid management in China and evaluate the association between fluid balance and survival outcomes in acute respiratory distress syndrome (ARDS) patients. A retrospective, multicenter study including ARDS patients was conducted. We described the fluid management of ARDS patients in China. Furthermore, clinical characteristics and outcomes of patients subdivided by cumulative fluid balance were also analyzed. Multivariable logistic regression analysis was performed with hospital mortality as the outcome. From June 2016 to February 2018, 527 ARDS patients were included in our study. The mean cumulative fluid balance was 1669 (-1101 to 4351) mL in the first 7 day after intensive care unit (ICU) admission. Patients were divided into four groups based on cumulative fluid balance of the first 7 day after ICU admission: Group I (≤0 L), Group II (>0 L, ≤3 L), Group III (>3 L, ≤5 L), and Group IV (>5 L). Significantly lower hospital mortality was observed in patients with a lower cumulative fluid balance on day 7 of ICU admission (20.5% in Group I vs. 32.8% in Group II, 38.5% in Group III, and 50% in Group IV, p < 0.001). A lower fluid balance is associated with lower hospital mortality in patients with ARDS. However, a large-scale and well-designed randomized controlled trial is needed in the future.

[Mesenchymal stem cells: Therapeutic option in ARDS, COPD, and COVID-19 patients]

Acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD) and COVID-19 have as a common characteristic the inflammatory lesion of the lung epithelium. The therapeutic options are associated with opportunistic infections, a hyperglycemic state, and adrenal involvement. Therefore, the search for new treatment strategies that reduce inflammation, and promote re-epithelialization of damaged tissue is very important. This work describes the relevant pathophysiological characteristics of these diseases and evaluates recent findings on the immunomodulatory, anti-inflammatory and regenerative effect of mesenchymal stem cells (MSC) and their therapeutic use. In Pubmed we selected the most relevant studies on the subject, published between 2003 and 2022 following the PRISMA guide. We conclude that MSCs are an important therapeutic option for regenerative treatment in COPD, ARDS, and COVID-19, because of their ability to differentiate into type II pneumocytes and maintain the size and function of lung tissue by replacing dead or damaged cells.

Sinomenine alleviates lipopolysaccharide-induced acute lung injury via a PPARβ/δ-dependent mechanism

Evidence is mounting that sinomenine and peroxisome proliferator-activated receptor β/δ (PPARβ/δ) are effective against lipopolysaccharide (LPS)-induced acute lung injury (ALI) via anti-inflammatory properties. However, it is unknown whether PPARβ/δ plays a role in the protective effect of sinomenine on ALI. Here, we initially observed that preemptive administration of sinomenine markedly alleviated lung pathological changes, pulmonary edema and neutrophil infiltration, accompanied by inhibition of the expression of the pro-inflammatory cytokines Tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6), which were largely reversed following the addition of a PPARβ/δ antagonist. Subsequently, we also noticed that sinomenine upregulated adenosine A_2A receptor expression in a PPARβ/δ-dependent manner in LPS-stimulated bone marrow-derived macrophages (BMDMs). Further investigation indicated that PPARβ/δ directly bound to the functional peroxisome proliferator responsive element (PPRE) in the adenosine A_2A receptor gene promoter region to enhance the expression of the adenosine A_2A receptor. Sinomenine was identified as a PPARβ/δ agonist. It could bind with PPARβ/δ, and promote the nuclear translocation and transcriptional activity of PPARβ/δ. In addition, combined treatment with sinomenine and an adenosine A_2A receptor agonist exhibited synergistic effects and better protective roles than their single use against ALI. Taken together, our results reveal that sinomenine exerts advantageous effects on ALI by activating of PPARβ/δ, with the subsequent upregulation of adenosine A_2A receptor expression, and provide a novel and potential therapeutic application for ALI.

Acute exacerbation of idiopathic pulmonary fibrosis model in the rats using bleomycin and lipopolysaccharides

Objective

This study was conducted to establish a rat model of acute exacerbation of idiopathic pulmonary fibrosis (AE-IPF) using the combination of bleomycin (BLM) and lipopolysaccharides (LPS).

Materials and Method

Twenty-four male Sprague Dawley rats were allocated into two equal groups: the sham or the bleomycin and lipopolysaccharides-induced AE-IPF group (BLM-LPS). On Day 7, BLM intratracheally and LPS intraperitoneally were both used to administer AE-IPF. The BLM-LPS group and its respective sham group were terminated on Days 8, 14, or 21. Samples of bronchoalveolar lavage fluid (BALF) and lungs were taken and investigated for cell count and histopathology.

Results

On Day 8, histological analysis revealed inflammatory cell infiltration with edema and hyaline membrane, and the BALF differential cell count revealed high neutrophil counts. By having a higher collagen density area and Ashcroft modified score than the sham group on Day 14, the BLM-LPS group displayed significantly lower oxygen saturation, alveolar air area, and a fibrotic appearance. However, there was a spontaneous resolution in inflammation and fibrotic appearance on Day 21 after the BLM administration.

Conclusions

By combining BLM and LPS, it was possible to create a successful rat model of AE-IPF. The present model showed the peak exacerbation on Day 8 and the fibrotic peak on Day 14, which gradually improved. The optimal time for the new AE-IPF therapeutic intervention was determined to be between Days 8 and 14.

Genetic Determinants of the Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a life-threatening lung condition that arises from multiple causes, including sepsis, pneumonia, trauma, and severe coronavirus disease 2019 (COVID-19). Given the heterogeneity of causes and the lack of specific therapeutic options, it is crucial to understand the genetic and molecular mechanisms that underlie this condition. The identification of genetic risks and pharmacogenetic loci, which are involved in determining drug responses, could help enhance early patient diagnosis, assist in risk stratification of patients, and reveal novel targets for pharmacological interventions, including possibilities for drug repositioning. Here, we highlight the basis and importance of the most common genetic approaches to understanding the pathogenesis of ARDS and its critical triggers. We summarize the findings of screening common genetic variation via genome-wide association studies and analyses based on other approaches, such as polygenic risk scores, multi-trait analyses, or Mendelian randomization studies. We also provide an overview of results from rare genetic variation studies using Next-Generation Sequencing techniques and their links with inborn errors of immunity. Lastly, we discuss the genetic overlap between severe COVID-19 and ARDS by other causes.

Basement membrane product, endostatin, as a link between inflammation, coagulation and vascular permeability in COVID-19 and non-COVID-19 acute respiratory distress syndrome

Background

Immune cell recruitment, endothelial cell barrier disruption, and platelet activation are hallmarks of lung injuries caused by COVID-19 or other insults which can result in acute respiratory distress syndrome (ARDS). Basement membrane (BM) disruption is commonly observed in ARDS, however, the role of newly generated bioactive BM fragments is mostly unknown. Here, we investigate the role of endostatin, a fragment of the BM protein collagen XVIIIα1, on ARDS associated cellular functions such as neutrophil recruitment, endothelial cell barrier integrity, and platelet aggregation in vitro.

Methods

In our study we analyzed endostatin in plasma and post-mortem lung specimens of patients with COVID-19 and non-COVID-19 ARDS. Functionally, we investigated the effect of endostatin on neutrophil activation and migration, platelet aggregation, and endothelial barrier function in vitro. Additionally, we performed correlation analysis for endostatin and other critical plasma parameters.

Results

We observed increased plasma levels of endostatin in our COVID-19 and non-COVID-19 ARDS cohort. Immunohistochemical staining of ARDS lung sections depicted BM disruption, alongside immunoreactivity for endostatin in proximity to immune cells, endothelial cells, and fibrinous clots. Functionally, endostatin enhanced the activity of neutrophils, and platelets, and the thrombin-induced microvascular barrier disruption. Finally, we showed a positive correlation of endostatin with soluble disease markers VE-Cadherin, c-reactive protein (CRP), fibrinogen, and interleukin (IL)-6 in our COVID-19 cohort.

Conclusion

The cumulative effects of endostatin on propagating neutrophil chemotaxis, platelet aggregation, and endothelial cell barrier disruption may suggest endostatin as a link between those cellular events in ARDS pathology.

[Effects and mechanism of annexin A1-overexpressing human adipose-derived mesenchymal stem cells in the treatment of mice with acute respiratory distress syndrome]

Objective: To explore the effects and mechanism of annexin A1 (ANXA1)-overexpressing human adipose-derived mesenchymal stem cells (AMSCs) in the treatment of mice with acute respiratory distress syndrome (ARDS). Methods: The experimental study method was adopted. After the adult AMSCs were identified by flow cytometry, the 3rd passage cells were selected for the follow-up experiments. According to the random number table (the same grouping method below), the cells were divided into ANXA1-overexpressing group transfected with plasmid containing RNA sequences of ANXA1 gene and no-load control group transfected with the corresponding no-load plasmid. The other cells were divided into ANXA1-knockdown group transfected with plasmid containing small interfering RNA sequences of ANXA1 gene and no-load control group transfected with the corresponding no-load plasmid. At post transfection hour (PTH) 72, the fluorescence expression was observed under a fluorescence microscope imaging system, and the protein and mRNA expressions of ANXA1 were detected by Western blotting and real-time fluorescence quantitative reverse transcription polymerase chain reaction respectively (with the sample numbers being 3). Fifty male C57BL/6J mice aged 6-8 weeks were divided into sham injury group, ARDS alone group, normal cell group, ANXA1-overexpressing group, and ANXA1-knockdown group, with 10 mice in each group. Mice in the last 4 groups were treated with endotoxin/lipopolysaccharide to make ARDS lung injury model, and mice in sham injury group were simulated to cause false injury. Immediately after injury, mice in sham injury group and ARDS alone group were injected with normal saline through the tail vein, while mice in normal cell group, ANXA1-overexpressing group, and ANXA1-knockdown group were injected with normal AMSCs, ANXA1-overexpressing AMSCs, and ANXA1-knockdown AMSCs, correspondingly. At post injection hour (PIH) 24, 5 mice in each group were selected, the Evans blue staining was performed to observe the gross staining of the right lung tissue, and the absorbance value of bronchoalveolar lavage fluid (BALF) supernatant of left lung was detected by microplate reader to evaluate the pulmonary vascular permeability. Three days after injection, the remaining 5 mice in each group were taken, the right lung tissue was collected for hematoxylin-eosin staining to observe the pathological changes and immunohistochemical staining to observe the CD11b and F4/80 positive macrophages, and the levels of tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and IL-1β in BALF supernatant of left lung were determined by enzyme-linked immunosorbent assay. Data were statistically analyzed with paired sample t test, one-way analysis of variance, and least significant difference test. Results: At PTH 72, AMSCs in both ANXA1-overexpressing group and ANXA1-knockdown group expressed higher fluorescence intensity than AMSCs in corresponding no-load control group, respectively. At PTH 72, compared with those in corresponding no-load control group, the protein and mRNA expressions of ANXA1 in ANXA1-overexpressing group were significantly increased (wth t values of 249.80 and 6.56, respectively, P<0.05), while the protein and mRNA expressions of ANXA1 in ANXA1-knockdown group were significantly decreased (wth t values of 176.50 and 18.18, respectively, P<0.05). At PIH 24, compared with those in sham injury group (with the absorbance value of BALF supernatant being 0.041±0.009), the lung tissue of mice in ARDS alone group was obviously blue-stained and the absorbance value of BALF supernatant (0.126±0.022) was significantly increased (P<0.05). Compared with those in ARDS alone group, the degree of blue-staining in lung tissue of mice was significantly reduced in normal cell group or ANXA1-overexpressing group, and the absorbance values of BALF supernatant (0.095±0.020 and 0.069±0.015) were significantly decreased (P<0.05), but the degree of blue-staining in lung tissue and the absorbance value of BALF supernatant (0.109±0.016, P>0.05) of mice in ANXA1-knockdown group had no significant change. Compared with that in normal cell group, the absorbance value of BALF supernatant of mice in ANXA1-overexpressing group was significantly decreased (P<0.05). Three days after injection, the lung tissue structure of mice in ARDS alone group was significantly damaged compared with that in sham injury group. Compared with those in ARDS alone group, hemorrhage, infiltration of inflammatory cells, alveolar collapse, and interstitial widening in the lung tissue of mice were significantly alleviated in normal cell group and ANXA1-overexpressing group, while no significant improvement of above-mentioned lung tissue manifestation was observed in ANXA1-knockdown group. Three days after injection, the numbers of CD11b and F4/80 positive macrophages in the lung tissue of mice in ARDS alone group were significantly increased compared with those in sham injury group. Compared with those in ARDS alone group, the numbers of CD11b and F4/80 positive macrophages in lung tissue of mice in normal cell group, ANXA1-overexpressing group, and ANXA1-knockdown group reduced, with the most significant reduction in ANXA1-overexpressing group. Three days after injection, compared with those in sham injury group, the levels of TNF-α, IL-6, and IL-1β in BALF supernatant of mice in ARDS alone group were significantly increased (P<0.05). Compared with those in ARDS alone group, the levels of TNF-α, IL-6, and IL-1β in BALF supernatant of mice in normal cell group and ANXA1-overexpressing group, as well as the level of IL-1β in BALF supernatant of mice in ANXA1-knockdown group were significantly decreased (P<0.05). Compared with that in normal cell group, the level of TNF-α in BALF supernatant of mice was significantly decreased in ANXA1-overexpressing group (P<0.05) but significantly increased in ANXA1-knockdown group (P<0.05). Conclusions: Overexpression of ANXA1 can optimize the efficacy of AMSCs in treating ARDS and enhance the effects of these cells in inhibiting inflammatory response and improving pulmonary vascular permeability, thereby alleviating lung injury of mice with ARDS.

Serum HMGB1 and soluble urokinase plasminogen activator receptor levels aid diagnosis and prognosis prediction of sepsis with acute respiratory distress syndrome

Objective: To study the clinical application of serum HMGB1 and soluble urokinase plasminogen activator receptor (suPAR) expression in sepsis with acute respiratory distress syndrome (ARDS). Methods: Clinical data of 303 septic patients with/without ARDS were documented. Levels of serum inflammatory markers and HMGB1/suPAR were measured. ARDS patients were subdivided into high and low HMGB1/suPAR expression groups and followed up. Results: Serum HMGB1 and suPAR were upregulated in ARDS patients and positively correlated with inflammatory markers. The combination of HMGB1 with suPAR surpassed HMGB1 or suPAR alone in aiding diagnosis of sepsis with ARDS. CRP, PCT, IL-6, HMGB1 and suPAR were independent risk factors for ARDS. High HMGB1/suPAR expression might be linked to poor prognosis. Conclusion: Serum HMGB1/suPAR levels might aid diagnosis and predict poor prognosis of septic patients with ARDS.

Unsymmetrical Phosphodiesters as GPR84 Antagonists with High Blood Exposure for the Treatment of Lung Inflammation

GPR84 is a proinflammatory G protein-coupled receptor that mediates myeloid immune cell functions. Blocking GPR84 with antagonists is a promising approach for treating inflammatory and fibrotic diseases. Previously, a GPR84 antagonist 604c, with a symmetrical phosphodiester structure, has displayed promising efficacy in a mouse model of ulcerative colitis. However, the low blood exposure resulting from physicochemical properties prevented its uses in other inflammatory diseases. In this study, a series of unsymmetrical phosphodiesters with lower lipophilicity were designed and tested. The representative compound 37 exhibited a 100-fold increase in mouse blood exposure compared to 604c while maintaining in vitro activity. In a mouse model of acute lung injury, 37 (30 mg/kg, po) significantly reduced the infiltration of proinflammatory cells and the release of inflammatory cytokines and ameliorated pathological changes equally or more effectively than N-acetylcysteine (100 mg/kg, po). These findings suggest that 37 is a promising candidate for treating lung inflammation.