[Effect of mild hypothermia on macrophage polarization in lipopolysaccharide-induced acute lung injury mice].

OBJECTIVE: To investigate the effect of mild hypothermia on macrophage polarization in lipopolysaccharide (LPS)-induced acute lung injury (ALI) mice and to clarify its role in lung injury. METHODS: According to a random number table method, 18 male C57BL/6 mice were divided into sham operation group (Sham group), ALI normothermic model group (NT group) and ALI mild hypothermia treatment group (HT group), with 6 mice in each group. The ALI model in mice was established by the method of tracheal instillation of LPS, and temperature control was administered at 1 hour after surgery. The anus temperature in NT group was kept at 36-38?centigrade, while the anus temperature in HT group was kept at 32-34?centigrade. The target anus temperature in both groups were maintained for 6 hours and then slowly rewarmed to 36-38 centigrade. The Sham group was infused with an equal amount of physiological saline through the trachea without temperature control. After 24 hours of modeling, serum was collected and mice were sacrificed to obtain lung tissue. Pathological changes in lung tissue were observed under light microscopy and semi-quantitative lung injury score was performed. Enzyme linked immunosorbent assay (ELISA) was used to detect the serum levels of interleukins (IL-1ß, IL-10). Real-time quantitative polymerase chain reaction (RT-qPCR) was used to test the indicators of macrophage polarization, such as the mRNA expressions of CD86, IL-6, CD206 and arginase 1 (Arg1) in the lung tissue. The protein expression of M1 macrophage marker inducible nitric oxide synthase (iNOS) and M2 macrophage marker Arg1 were detected by Western blotting. RESULTS: Compared with the Sham group, the NT group appeared significant pulmonary hemorrhage and edema, thickened lung septum, inflammatory cell infiltration, and lung injury score was significantly increased; serum IL-1ß level was significantly elevated; IL-10 level was increased without statistical significance; the expressions of CD86 mRNA, IL-6 mRNA and iNOS protein were significantly elevated, and CD206 mRNA was significantly decreased; the mRNA and protein expressions of Arg1 decreased, but there were no significant differences. Compared with the NT group, the pathological injury of lung tissue in HT group was significantly reduced, and the lung injury score was significantly decreased (4.78±0.96 vs. 8.56±1.98, P < 0.01); serum IL-1ß level was decreased (ng/L: 13.52±1.95 vs. 27.18±3.87, P < 0.01), and IL-10 level was significantly increased (ng/L: 42.59±15.79 vs. 14.62±4.47, P < 0.01); IL-6 mRNA expression was decreased in lung tissue (2-ΔΔCt: 3.37±0.92 vs. 10.04±0.91, P < 0.05), the expression of M1 macrophage markers CD86 mRNA and iNOS protein were significantly decreased [CD86 mRNA (2-ΔΔCt): 0.52±0.16 vs. 1.95±0.33, iNOS protein (iNOS/ß-actin): 0.57±0.19 vs. 1.11±0.27, both P < 0.05], the expression of M2 macrophage markers CD206 mRNA, Arg1 mRNA and Arg1 protein were significantly increased [CD206 mRNA (2-ΔΔCt): 3.99±0.17 vs. 0.34±0.17, Arg1 mRNA (2-ΔΔCt): 2.33±0.73 vs. 0.94±0.23, Arg1 protein (Arg1/ß-actin): 0.96±0.09 vs. 0.31±0.11, all P < 0.05]. CONCLUSIONS: Mild hypothermia can alleviate the inflammatory response and protect lung tissue in ALI mice, which may be related to the inhibition of M1 macrophage polarization and promotion of M2 macrophage polarization.

Cholesterol-Modified Anti-Il6 siRNA Reduces the Severity of Acute Lung Injury in Mice.

Small interfering RNA (siRNA) holds significant therapeutic potential by silencing target genes through RNA interference. Current clinical applications of siRNA have been primarily limited to liver diseases, while achievements in delivery methods are expanding their applications to various organs, including the lungs. Cholesterol-conjugated siRNA emerges as a promising delivery approach due to its low toxicity and high efficiency. This study focuses on developing a cholesterol-conjugated anti-Il6 siRNA and the evaluation of its potency for the potential treatment of inflammatory diseases using the example of acute lung injury (ALI). The biological activities of different Il6-targeted siRNAs containing chemical modifications were evaluated in J774 cells in vitro. The lead cholesterol-conjugated anti-Il6 siRNA after intranasal instillation demonstrated dose-dependent therapeutic effects in a mouse model of ALI induced by lipopolysaccharide (LPS). The treatment significantly reduced Il6 mRNA levels, inflammatory cell infiltration, and the severity of lung inflammation. IL6 silencing by cholesterol-conjugated siRNA proves to be a promising strategy for treating inflammatory diseases, with potential applications beyond the lungs.

[Research progress of the role of non-coding RNA in hyperoxia-induced acute lung injury].

Hyperoxia-induced acute lung injury (HALI) is an important complication of clinical oxygen therapy, which is mainly characterized by acute respiratory distress syndrome (ARDS) in adults and broncho-pulmonary dysplasia (BPD) in infants. HALI seriously affects the prognosis and quality of life of patients, so it has received more and more attention. However, the pathogenesis of HALI is complex and unclear, and there is no clear treatment method at present. Non-coding RNA (ncRNA) is an important type of functional RNA transcriptome. Due to the lack of effective open reading frame, ncRNA does not have the function of coding proteins. However, ncRNA can still regulate gene expression at multiple levels and affect the occurrence and development of many diseases. In recent years, a large number of in vitro and in vivo studies have shown that ncRNA is involved in the pathogenesis of HALI and is of great significance. This article reviews the expression and significance of ncRNA in HALI, in order to provide new diagnosis and treatment ideas for the prevention and treatment of HALI.

Predictors associated with successful weaning of veno-venous extracorporeal membrane oxygenation and mortality in adult patients with severe acute lung failure: Protocol of a pooled data analysis of cohort studies.

BACKGROUND: Severe acute lung failure (ALF) often necessitates veno-venous extracorporeal membrane oxygenation (VV-ECMO), where identifying predictors of weaning success and mortality remains crucial yet challenging. The study aims to identify predictors of weaning success and mortality in adults undergoing VV-ECMO for severe ALF, a gap in current clinical knowledge. METHODS AND ANALYSIS: PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials will be searched for cohort studies examining the predictive factors of successful weaning and mortality in adult patients on VV-ECMO due to severe ALF. Risk of bias assessment will be conducted using the Newcastle-Ottawa scale for each included study. The primary outcomes will be successful weaning from VV-ECMO and all-cause mortality. Between-study heterogeneity will be evaluated using the I2 statistic. Sensitivity, subgroup, and meta-regression analyses will be performed to ascertain potential sources of heterogeneity and assess the robustness of our results. We will use the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) tool to recommend the level of evidence. DISCUSSION: This study seeks to provide clinically significant insights into predictors for weaning and mortality during VV-ECMO treatment for ALF, aiming to support clinical decisions and potentially influence health policy, thereby improving patient outcomes. ETHICS AND DISSEMINATION: Given the absence of direct engagement with human subjects or access to personal medical records, ethical approval for this study is deemed unnecessary. The study findings will be shared at a scientific conference either at the global or national level. Alternatively, the results will be presented for publication in a rigorously peer-reviewed journal regarding critical care medicine.

Endothelial cell-derived extracellular vesicles modulate the therapeutic efficacy of mesenchymal stem cells through IDH2/TET pathway in ARDS.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a severe and fatal disease. Although mesenchymal stem cell (MSC)-based therapy has shown remarkable efficacy in treating ARDS in animal experiments, clinical outcomes have been unsatisfactory, which may be attributed to the influence of the lung microenvironment during MSC administration. Extracellular vesicles (EVs) derived from endothelial cells (EC-EVs) are important components of the lung microenvironment and play a crucial role in ARDS. However, the effect of EC-EVs on MSC therapy is still unclear. In this study, we established lipopolysaccharide (LPS) - induced acute lung injury model to evaluate the impact of EC-EVs on the reparative effects of bone marrow-derived MSC (BM-MSC) transplantation on lung injury and to unravel the underlying mechanisms. METHODS: EVs were isolated from bronchoalveolar lavage fluid of mice with LPS - induced acute lung injury and patients with ARDS using ultracentrifugation. and the changes of EC-EVs were analysed using nanoflow cytometry analysis. In vitro assays were performed to establish the impact of EC-EVs on MSC functions, including cell viability and migration, while in vivo studies were performed to validate the therapeutic effect of EC-EVs on MSCs. RNA-Seq analysis, small interfering RNA (siRNA), and a recombinant lentivirus were used to investigate the underlying mechanisms. RESULTS: Compared with that in non-ARDS patients, the quantity of EC-EVs in the lung microenvironment was significantly greater in patients with ARDS. EVs derived from lipopolysaccharide-stimulated endothelial cells (LPS-EVs) significantly decreased the viability and migration of BM-MSCs. Furthermore, engrafting BM-MSCs pretreated with LPS-EVs promoted the release of inflammatory cytokines and increased pulmonary microvascular permeability, aggravating lung injury. Mechanistically, LPS-EVs reduced the expression level of isocitrate dehydrogenase 2 (IDH2), which catalyses the formation of α-ketoglutarate (α-KG), an intermediate product of the tricarboxylic acid (TCA) cycle, in BM-MSCs. α-KG is a cofactor for ten-eleven translocation (TET) enzymes, which catalyse DNA hydroxymethylation in BM-MSCs. CONCLUSIONS: This study revealed that EC-EVs in the lung microenvironment during ARDS can affect the therapeutic efficacy of BM-MSCs through the IDH2/TET pathway, providing potential strategies for improving the therapeutic efficacy of MSC-based therapy in the clinic.

Association between high-flow nasal cannula use and mortality in patients with sepsis-induced acute lung injury: a retrospective propensity score-matched cohort study.

BACKGROUND: High-flow nasal cannula (HFNC) has emerged as a promising noninvasive method for delivering oxygen to critically ill patients, particularly those with sepsis and acute lung injury. However, uncertainties persist regarding its therapeutic benefits in this specific patient population. METHODS: This retrospective study utilized a propensity score-matched cohort from the Medical Information Mart in Intensive Care-IV (MIMIC-IV) database to explore the correlation between HFNC utilization and mortality in patients with sepsis-induced acute lung injury. The primary outcome was 28-day all-cause mortality. RESULTS: In the propensity score-matched cohort, the 28-day all-cause mortality rate was 18.63% (95 out of 510) in the HFNC use group, compared to 31.18% (159 out of 510) in the non-HFNC group. The use of HFNC was associated with a lower 28-day all-cause mortality rate (hazard ratio [HR] = 0.53; 95% confidence interval [CI] = 0.41-0.69; P < 0.001). HFNC use was also associated with lower ICU mortality (odds ratio [OR] = 0.52; 95% CI = 0.38-0.71; P < 0.001) and lower in-hospital mortality (OR = 0.51; 95% CI = 0.38-0.68; P < 0.001). Additionally, HFNC use was found to be associated with a statistically significant increase in both the ICU and overall hospitalization length. CONCLUSIONS: These findings indicate that HFNC may be beneficial for reducing mortality rates among sepsis-induced acute lung injury patients; however, it is also associated with longer hospital stays.

STING-deficiency in lung resident mesenchymal stromal cells contributes to the alleviation of LPS-induced lung injury.

Acute respiratory distress syndrome (ARDS) is characterized by acute diffuse inflammatory lung injury with a high mortality rate. Mesenchymal stromal cells (MSC) are pluripotent adult cells that can be extracted from a variety of tissues, including the lung. Lung-resident MSC (LR-MSC) located around vascular vessels and act as important regulators of lung homeostasis, regulating the balance between lung injury and repair processes. LR-MSC support the integrity of lung tissue by modulating immune responses and releasing trophic factors. Studies have reported that the STING pathway is involved in the progression of lung injury inflammation, but the specific mechanism is unclear. In this study, we found that STING deficiency could ameliorate lipopolysaccharides (LPS)-induced acute lung injury, STING knockout (STING KO) LR-MSC had an enhanced treatment effect on acute lung injury. STING depletion protected LR-MSC from LPS-induced apoptosis. RNA-sequencing and Western blot results showed that STING KO LR-MSC expressed higher levels of MSC immunoregulatory molecules, such as Igfbp4, Icam1, Hgf and Cox2, than WT LR-MSC. This study highlights that LR-MSC have a therapeutic role in acute lung injury, and we demonstrate that STING deficiency can enhance the immunomodulatory function of LR-MSC in controlling lung inflammation. Thus, STING can be used as an intervention target to enhance the therapeutic effect of MSC.

Immunometabolic reprogramming of macrophages with inhalable CRISPR/Cas9 nanotherapeutics for acute lung injury intervention.

Acute lung injury (ALI) represents a critical respiratory condition typified by rapid-onset lung inflammation, contributing to elevated morbidity and mortality rates. Central to ALI pathogenesis lies macrophage dysfunction, characterized by an overabundance of pro-inflammatory cytokines and a shift in metabolic activity towards glycolysis. This study emphasizes the crucial function of glucose metabolism in immune cell function under inflammatory conditions and identifies hexokinase 2 (HK2) as a key regulator of macrophage metabolism and inflammation. Given the limitations of HK2 inhibitors, we propose the CRISPR/Cas9 system for precise HK2 downregulation. We developed an aerosolized core-shell liposomal nanoplatform (CSNs) complexed with CaP for efficient drug loading, targeting lung macrophages. Various CSNs were synthesized to encapsulate an mRNA based CRISPR/Cas9 system (mCas9/gHK2), and their gene editing efficiency and HK2 knockout were examined at both gene and protein levels in vitro and in vivo. The CSN-mCas9/gHK2 treatment demonstrated a significant reduction in glycolysis and inflammation in macrophages. In an LPS-induced ALI mouse model, inhaled CSN-mCas9/gHK2 mitigated the proinflammatory tumor microenvironment and reprogrammed glucose metabolism in the lung, suggesting a promising strategy for ALI prevention and treatment. This study highlights the potential of combining CRISPR/Cas9 gene editing with inhalation delivery systems for effective, localized pulmonary disease treatment, underscoring the importance of targeted gene modulation and metabolic reprogramming in managing ALI. STATEMENT OF SIGNIFICANCE: This study investigates an inhalable CRISPR/Cas9 gene editing system targeting pulmonary macrophages, with the aim of modulating glucose metabolism to alleviate Acute Lung Injury (ALI). The research highlights the role of immune cell metabolism in inflammation, as evidenced by changes in macrophage glucose metabolism and a notable reduction in pulmonary edema and inflammation. Additionally, observed alterations in macrophage polarization and cytokine levels in bronchoalveolar lavage fluid suggest potential therapeutic implications. These findings not only offer insights into possible ALI treatments but also contribute to the understanding of immune cell metabolism in inflammatory diseases, which could be relevant for various inflammatory and metabolic disorders.

Manufacturing, quality control, and GLP-grade preclinical study of nebulized allogenic adipose mesenchymal stromal cells-derived extracellular vesicles.

BACKGROUND: Human adipose stromal cells-derived extracellular vesicles (haMSC-EVs) have been shown to alleviate inflammation in acute lung injury (ALI) animal models. However, there are few systemic studies on clinical-grade haMSC-EVs. Our study aimed to investigate the manufacturing, quality control (QC) and preclinical safety of clinical-grade haMSC-EVs. METHODS: haMSC-EVs were isolated from the conditioned medium of human adipose MSCs incubated in 2D containers. Purification was performed by PEG precipitation and differential centrifugation. Characterizations were conducted by nanoparticle tracking analysis, transmission electron microscopy (TEM), Western blotting, nanoflow cytometry analysis, and the TNF-α inhibition ratio of macrophage [after stimulated by lipopolysaccharide (LPS)]. RNA-seq and proteomic analysis with liquid chromatography tandem mass spectrometry (LC-MS/MS) were used to inspect the lot-to-lot consistency of the EV products. Repeated toxicity was evaluated in rats after administration using trace liquid endotracheal nebulizers for 28 days, and respiratory toxicity was evaluated 24 h after the first administration. In vivo therapeutic effects were assessed in an LPS-induced ALI/ acute respiratory distress syndrome (ARDS) rat model. RESULTS: The quality criteria have been standardized. In a stability study, haMSC-EVs were found to remain stable after 6 months of storage at - 80°C, 3 months at - 20 °C, and 6 h at room temperature. The microRNA profile and proteome of haMSC-EVs demonstrated suitable lot-to-lot consistency, further suggesting the stability of the production processes. Intratracheally administered 1.5 × 108 particles/rat/day for four weeks elicited no significant toxicity in rats. In LPS-induced ALI/ARDS model rats, intratracheally administered haMSC-EVs alleviated lung injury, possibly by reducing the serum level of inflammatory factors. CONCLUSION: haMSC-EVs, as an off-shelf drug, have suitable stability and lot-to-lot consistency. Intratracheally administered haMSC-EVs demonstrated excellent safety at the tested dosages in systematic preclinical toxicity studies. Intratracheally administered haMSC-EVs improved the lung function and exerted anti-inflammatory effects on LPS-induced ALI/ARDS model rats.

Alveolar-capillary endocytosis and trafficking in acute lung injury and acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is associated with high morbidity and mortality but lacks specific therapeutic options. Diverse endocytic processes play a key role in all phases of acute lung injury (ALI), including the initial insult, development of respiratory failure due to alveolar flooding, as a consequence of altered alveolar-capillary barrier function, as well as in the resolution or deleterious remodeling after injury. In particular, clathrin-, caveolae-, endophilin- and glycosylphosphatidyl inositol-anchored protein-mediated endocytosis, as well as, macropinocytosis and phagocytosis have been implicated in the setting of acute lung damage. This manuscript reviews our current understanding of these endocytic pathways and subsequent intracellular trafficking in various phases of ALI, and also aims to identify potential therapeutic targets for patients with ARDS.

Engineered extracellular vesicles carrying let-7a-5p for alleviating inflammation in acute lung injury.

BACKGROUND: Acute lung injury (ALI) is a life-threatening respiratory condition characterized by severe inflammation and lung tissue damage, frequently causing rapid respiratory failure and long-term complications. The microRNA let-7a-5p is involved in the progression of lung injury, inflammation, and fibrosis by regulating immune cell activation and cytokine production. This study aims to use an innovative cellular electroporation platform to generate extracellular vesicles (EVs) carring let-7a-5p (EV-let-7a-5p) derived from transfected Wharton's jelly-mesenchymal stem cells (WJ-MSCs) as a potential gene therapy for ALI. METHODS: A cellular nanoporation (CNP) method was used to induce the production and release of EV-let-7a-5p from WJ-MSCs transfected with the relevant plasmid DNA. EV-let-7a-5p in the conditioned medium were isolated using a tangential flow filtration (TFF) system. EV characterization followed the minimal consensus guidelines outlined by the International Society for Extracellular Vesicles. We conducted a thorough set of therapeutic assessments, including the antifibrotic effects using a transforming growth factor beta (TGF-ß)-induced cell model, the modulation effects on macrophage polarization, and the influence of EV-let-7a-5p in a rat model of hyperoxia-induced ALI. RESULTS: The CNP platform significantly increased EV secretion from transfected WJ-MSCs, and the encapsulated let-7a-5p in engineered EVs was markedly higher than that in untreated WJ-MSCs. These EV-let-7a-5p did not influence cell proliferation and effectively mitigated the TGF-ß-induced fibrotic phenotype by downregulating SMAD2/3 phosphorylation in LL29 cells. Furthermore, EV-let-7a-5p regulated M2-like macrophage activation in an inflammatory microenvironment and significantly induced interleukin (IL)-10 secretion, demonstrating their modulatory effect on inflammation. Administering EVs from untreated WJ-MSCs slightly improved lung function and increased let-7a-5p expression in plasma in the hyperoxia-induced ALI rat model. In comparison, EV-let-7a-5p significantly reduced macrophage infiltration and collagen deposition while increasing IL-10 expression, causing a substantial improvement in lung function. CONCLUSION: This study reveals that the use of the CNP platform to stimulate and transfect WJ-MSCs could generate an abundance of let-7a-5p-enriched EVs, which underscores the therapeutic potential in countering inflammatory responses, fibrotic activation, and hyperoxia-induced lung injury. These results provide potential avenues for developing innovative therapeutic approaches for more effective interventions in ALI.

Recent progress in mesenchymal stem cell-based therapy for acute lung injury.

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are life-threatening diseases in critically ill patients. Although pathophysiology of ALI/ARDS has been investigated in many studies, effective therapeutic strategies are still limited. Mesenchymal stem cell (MSC)-based therapy is emerging as a promising therapeutic intervention for patients with ALI. During the last two decades, researchers have focused on the efficacy and mechanism of MSC application in ALI animal models. MSC derived from variant resources exhibited therapeutic effects in preclinical studies of ALI with different mechanisms. Based on this, clinical studies on MSC treatment in ALI/ARDS has been tried recently, especially in COVID-19 caused lung injury. Emerging clinical trials of MSCs in treating COVID-19-related conditions have been registered in past two years. The advantages and potential of MSCs in the defense against COVID-19-related ALI or ARDS have been confirmed. This review provides a brief overview of recent research progress in MSC-based therapies in preclinical study and clinical trials in ALI treatment, as well as the underlying mechanisms.

The efficacy of extracellular vesicles for acute lung injury in preclinical animal models: a meta-analysis.

BACKGROUND: With the increasing research on extracellular vesicles (EVs), EVs have received widespread attention as biodiagnostic markers and therapeutic agents for a variety of diseases. Stem cell-derived EVs have also been recognized as a new viable therapy for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). To assess their efficacy, we conducted a meta-analysis of existing preclinical experimental animal models of EVs for ALI treatment. METHODS: The database was systematically interrogated for pertinent data encompassing the period from January 2010 to April 2022 concerning interventions involving extracellular vesicles (EVs) in animal models of acute lung injury (ALI). The lung injury score was selected as the primary outcome measure for statistical analysis. Meta-analyses were executed utilizing RevMan 5.3 and State15.1 software tools. RESULTS: The meta-analyses comprised 31 studies, exclusively involving animal models of acute lung injury (ALI), categorized into two cohorts based on the presence or absence of extracellular vesicle (EV) intervention. The statistical outcomes from these two study groups revealed a significant reduction in lung injury scores with the administration of stem and progenitor cell-derived EVs (SMD = -3.63, 95% CI [-4.97, -2.30], P < 0.05). Conversely, non-stem cell-derived EVs were associated with an elevation in lung injury scores (SMD = -4.34, 95% CI [3.04, 5.63], P < 0.05). EVs originating from stem and progenitor cells demonstrated mitigating effects on alveolar neutrophil infiltration, white blood cell counts, total cell counts in bronchoalveolar lavage fluid (BALF), lung wet-to-dry weight ratios (W/D), and total protein in BALF. Furthermore, pro-inflammatory mediators exhibited down-regulation, while anti-inflammatory mediators demonstrated up-regulation. Conversely, non-stem cell-derived EVs exacerbated lung injury. CONCLUSION: In preclinical animal models of acute lung injury (ALI), the administration of extracellular vesicles (EVs) originating from stem and progenitor cells demonstrably enhances pulmonary function. This ameliorative effect is attributed to the mitigation of pulmonary vascular permeability and the modulation of immune homeostasis, collectively impeding the progression of inflammation. In stark contrast, the utilization of EVs derived from non-stem progenitor cells exacerbates the extent of lung injury. These findings substantiate the potential utility of EVs as a novel therapeutic avenue for addressing acute lung injury.

MSCs alleviate LPS-induced acute lung injury by inhibiting the proinflammatory function of macrophages in mouse lung organoid-macrophage model.

Acute lung injury (ALI) is an inflammatory disease associated with alveolar injury, subsequent macrophage activation, inflammatory cell infiltration, and cytokine production. Mesenchymal stem cells (MSCs) are beneficial for application in the treatment of inflammatory diseases due to their immunomodulatory effects. However, the mechanisms of regulatory effects by MSCs on macrophages in ALI need more in-depth study. Lung tissues were collected from mice for mouse lung organoid construction. Alveolar macrophages (AMs) derived from bronchoalveolar lavage and interstitial macrophages (IMs) derived from lung tissue were co-cultured, with novel matrigel-spreading lung organoids to construct an in vitro model of lung organoids-immune cells. Mouse compact bone-derived MSCs were co-cultured with organoids-macrophages to confirm their therapeutic effect on acute lung injury. Changes in transcriptome expression profile were analyzed by RNA sequencing. Well-established lung organoids expressed various lung cell type-specific markers. Lung organoids grown on spreading matrigel had the property of functional cells growing outside the lumen. Lipopolysaccharide (LPS)-induced injury promoted macrophage chemotaxis toward lung organoids and enhanced the expression of inflammation-associated genes in inflammation-injured lung organoids-macrophages compared with controls. Treatment with MSCs inhibited the injury progress and reduced the levels of inflammatory components. Furthermore, through the nuclear factor-κB pathway, MSC treatment inhibited inflammatory and phenotypic transformation of AMs and modulated the antigen-presenting function of IMs, thereby affecting the inflammatory phenotype of lung organoids. Lung organoids grown by spreading matrigel facilitate the reception of external stimuli and the construction of in vitro models containing immune cells, which is a potential novel model for disease research. MSCs exert protective effects against lung injury by regulating different functions of AMs and IMs in the lung, indicating a potential mechanism for therapeutic intervention.

Bone mesenchymal stem cell-derived exosomal miR-26a-3p promotes autophagy to attenuate LPS-induced apoptosis and inflammation in pulmonary microvascular endothelial cells.

Acute lung injury (ALI) is a serious lung disease. The apoptosis and inflammation of pulmonary microvascular endothelial cells (PMVECs) are the primary reasons for ALI. This study aimed to explore the treatment effect and regulatory mechanism of bone mesenchymal stem cell-derived exosomes (BMSC-expos) on ALI. PMVECs were stimulated by Lipopolysaccharide (LPS) to imitate ALI environment. Cell viability was determined by CCK-8 assay. Cell apoptosis was evaluated by TUNEL and flow cytometry. ELISA was utilized for testing the contents of TNF-α, IL-1ß, IL-6, and IL-17. Western blot was applied for testing the levels of autophagy-related proteins LC3, p62, and Beclin-1. RNA interaction was determined by luciferase reporter assay. The ALI rat model was established by intratracheal injection of LPS. Evans blue staining was utilized for detecting pulmonary vascular permeability. Our results showed that LPS stimulation notably reduced cell viability, increased cell apoptosis rate, and enhanced the contents of inflammatory factors in PMVECs. However, BMSC-exo treatment significantly abolished the promoting effects of LPS on cell injury. In addition, we discovered that BMSC-exo treatment notably activated autophagy in LPS-induced PMVECs. Furthermore, BMSC-expos upregulated miR-26a-3p expression and downregulated PTEN in PMVECs. MiR-26a-3p was directly bound to PTEN. MiR-26a-3p overexpression reduced cell apoptosis, and inflammation and promoted autophagy by silencing PTEN. Animal experiments proved that miR-26a-3p overexpression effectively improved LPS-induced lung injury in rats. The results proved that BMSC-expos promotes autophagy to attenuate LPS-induced apoptosis and inflammation in pulmonary microvascular endothelial cells via miR-26a-3p/PTEN axis.

Mesenchymal Stem Cells-Derived Exosomes Alleviate Acute Lung Injury by Inhibiting Alveolar Macrophage Pyroptosis.

Acute lung injury (ALI) is an important pathological process of acute respiratory distress syndrome, yet there are limited therapies for its treatment. Mesenchymal stem cells-derived exosomes (MSCs-Exo) have been shown to be effective in suppressing inflammation. However, the effects of MSCs-Exo on ALI and the underlying mechanisms have not been well elucidated. Our data showed that MSCs-Exo, but not exosomes derived from MRC-5 cells (MRC-5-Exo), which are human fetal lung fibroblast cells, significantly improved chest imaging, histological observations, alveolocapillary membrane permeability, and reduced inflammatory response in ALI mice model. According to miRNA sequencing and proteomic analysis of MSCs-Exo and MRC-5-Exo, MSCs-Exo may inhibit pyroptosis by miRNAs targeting caspase-1-mediated pathway, and by proteins with immunoregulation functions. Taken together, our study demonstrated that MSCs-Exo were effective in treating ALI by inhibiting the pyroptosis of alveolar macrophages and reducing inflammation response. Its mechanism may be through pyroptosis-targeting miRNAs and immunoregulating proteins delivered by MSCs-Exo. Therefore, MSCs-Exo may be a new treatment option in the early stage of ALI.

Pulmonary RNA interference against acute lung injury mediated by mucus- and cell-penetrating nanocomplexes.

Trans-mucosal delivery of anti-inflammatory siRNA into alveolar macrophages represents a promising modality for the treatment of acute lung injury (ALI). However, its therapeutic efficacy is often hurdled by the lack of effective carriers that can simultaneously overcome the mucosal barrier and cell membrane barrier. Herein, we developed mucus/cell membrane dual-penetrating, macrophage-targeting polyplexes which enabled efficient intratracheal delivery of TNF-α siRNA (siTNF-α) to attenuate pulmonary inflammation against lipopolysaccharide (LPS)-induced ALI. P-G@Zn, a cationic helical polypeptide bearing both guanidine and zinc dipicolylamine (Zn-DPA) side charged groups, was designed to condense siTNF-α and promote macrophage internalization due to its helicity-dependent membrane activity. Coating of the polyplexes with charge-neutralizing carboxylated mannan (Man-COOH) greatly enhanced the mucus penetration potency due to shielding of the electrostatic adhesive interactions with the mucus, and it cooperatively enabled active targeting to alveolar macrophages to potentiate the intracellular delivery efficiency of siTNF-α. As such, intratracheally administered Man-COOH/P-G@Zn/siTNF-α polyplexes provoked notable TNF-α silencing by ∼75 % in inflamed lung tissues at 500 µg siRNA/kg, and demonstrated potent anti-inflammatory performance to treat ALI. This study provides an effective tool for the synchronized trans-mucosal delivery of siRNA into macrophages, and the unique properties of the polyplexes render remarkable potentials for anti-inflammatory therapy against ALI. STATEMENT OF SIGNIFICANCE: siRNA-mediated anti-inflammatory management of acute lung injury (ALI) is greatly challenged by the insufficient delivery across the mucus layer and cell membrane. To address such critical issue, mucus/cell membrane dual-penetrating, macrophage-targeting polyplexes are herein developed, which are comprised of an outer shell of carboxylated mannan (Man-COOH) and an inner nanocore formed by TNF-α siRNA (siTNF-α) and a cationic helical polypeptide P-G@Zn. Man-COOH coating endowed the polyplexes with high mucus-penetrating capability and macrophage-targeting ability, while P-G@Zn bearing both guanidine and zinc dipicolylamine afforded potent siTNF-α condensation capacity and high intracellular delivery efficiency with reduced cytotoxicity. Intratracheally administered polyplexes solicit pronounced TNF-α silencing and anti-inflammatory efficiencies in ALI mice. This study renders an effective example for overcoming the multiple barriers against trans-mucosal delivery of siRNA into macrophages, and holds profound potentials for gene therapy against ALI.

High-intensity intermittent training ameliorates methotrexate-induced acute lung injury.

Inflammation and oxidative stress are recognized as two primary causes of lung damage induced by methotrexate, a drug used in the treatment of cancer and immunological diseases. This drug triggers the generation of oxidants, leading to lung injury. Given the antioxidant and anti-inflammatory effects of high-intensity intermittent training (HIIT), our aim was to evaluate the therapeutic potential of HIIT in mitigating methotrexate-induced lung damage in rats. Seventy male Wistar rats were randomly divided into five groups: CTL (Control), HIIT (High-intensity intermittent training), ALI (Acute Lung Injury), HIIT+ALI (pretreated with HIIT), and ALI + HIIT (treated with HIIT).HIIT sessions were conducted for 8 weeks. At the end of the study, assessments were made on malondialdehyde, total antioxidant capacity (TAC), superoxide dismutase (SOD), glutathione peroxidase (Gpx), myeloperoxidase (MPO), interleukin 10 (IL-10), tumor necrosis factor-alpha (TNF-α), gene expression of T-bet, GATA3, FOXP3, lung wet/dry weight ratio, pulmonary capillary permeability, apoptosis (Caspase-3), and histopathological indices.Methotrexate administration resulted in increased levels of TNF-α, MPO, GATA3, caspase-3, and pulmonary edema indices, while reducing the levels of TAC, SOD, Gpx, IL-10, T-bet, and FOXP3. Pretreatment and treatment with HIIT reduced the levels of oxidant and inflammatory factors, pulmonary edema, and other histopathological indicators. Concurrently, HIIT increased the levels of antioxidant and anti-inflammatory factors.

Umbilical cord MSC-derived exosomes improve alveolar macrophage function and reduce LPS-induced acute lung injury.

Acute lung injury (ALI) is a severe condition that can progress to acute respiratory distress syndrome (ARDS), with a high mortality rate. Currently, no specific and compelling drug treatment plan exists. Mesenchymal stem cells (MSCs) have shown promising results in preclinical and clinical studies as a potential treatment for ALI and other lung-related conditions due to their immunomodulatory properties and ability to regenerate various cell types. The present study focuses on analyzing the role of umbilical cord MSC (UC-MSC))-derived exosomes in reducing lipopolysaccharide-induced ALI and investigating the mechanism involved. The study demonstrates that UC-MSC-derived exosomes effectively improved the metabolic function of alveolar macrophages and promoted their shift to an anti-inflammatory phenotype, leading to a reduction in ALI. The findings also suggest that creating three-dimensional microspheres from the MSCs first can enhance the effectiveness of the exosomes. Further research is needed to fully understand the mechanism of action and optimize the therapeutic potential of MSCs and their secretome in ALI and other lung-related conditions.