Extracellular Vesicles: A New Frontier for Research in Acute Respiratory Distress Syndrome

Endothelium-Derived Engineered Extracellular Vesicles Protect the Pulmonary Endothelial Barrier in Acute Lung Injury

Acute lung injury (ALI) is a severe respiratory disease with a high mortality rate. The integrity of the pulmonary endothelial barrier influences the development and prognosis of ALI. Therefore, it has become an important target for ALI treatment. Extracellular vesicles (EVs) are promising nanotherapeutic agents against ALI. Herein, endothelium-derived engineered extracellular vesicles (eEVs) that deliver microRNA-125b-5p (miRNA-125b) to lung tissues exerting a protective effect on endothelial barrier integrity are reported. eEVs that are modified with lung microvascular endothelial cell-targeting peptides (LET) exhibit a prolonged retention time in lung tissues and targeted lung microvascular endothelial cells in vivo and in vitro. To improve the efficacy of the EVs, miRNA-125b is loaded into EVs. Finally, LET-EVs-miRNA-125b is constructed. The results show that compared to the EVs, miRNA-125b, and EVs-miRNA-125b, LET-EVs-miRNA-125b exhibit the most significant treatment efficacy in ALI. Moreover, LET-EVs-miRNA-125b is found to have an important protective effect on endothelial barrier integrity by inhibiting cell apoptosis, promoting angiogenesis, and protecting intercellular junctions. Sequencing analysis reveals that LET-EVs-miRNA-125b downregulates early growth response-1 (EGR1) levels, which may be a potential mechanism of action. Taken together, these findings suggest that LET-EVs-miRNA-125b can treat ALI by protecting the endothelial barrier integrity.

Regenerative Signatures in Bronchioalveolar Lavage of Acute Respiratory Distress Syndrome

Background

In patients with severe acute respiratory distress syndrome (ARDS) associated with sepsis, lung recovery is considerably delayed, and mortality is much high. More insight into the process of lung regeneration in ARDS patients is needed. Exosomes are important cargos for intercellular communication by serving as autocrine and/or paracrine. Cutting-edge exomics (exosomal proteomics) makes it possible to study the mechanisms of re-alveolarization in ARDS lungs.

Aims

This study aimed to identify potential regenerative niches by characterizing differentially expressed proteins in the exosomes of bronchioalveolar lavage (BAL) in ARDS patients.

Methods

We purified exosomes from BAL samples collected from ARDS patients by NIH-supported ALTA and SPIROMICS trials. The abundance of exosomal proteins/peptides was quantified using liquid chromatography-mass spectrometry (LC-MS). Differentially expressed exosomal proteins between healthy controls and ARDS patients were profiled for functional annotations, cell origins, signaling pathways, networks, and clinical correlations.

Results

Our results show that more exosomal proteins were identified in the lungs of late-stage ARDS patients. Immune cells and lung epithelial stem cells were major contributors to BAL exosomes in addition to those from other organs. We enriched a wide range of functions, stem cell signals, growth factors, and immune niches in both mild and severe patients. The differentially expressed proteins that we identified were associated with key clinical variables. The severity-associated differences in protein-protein interaction, RNA crosstalk, and epigenetic network were observed between mild and severe groups. Moreover, alveolar type 2 epithelial cells could serve as both exosome donors and recipients via autocrine and paracrine mechanisms.

Conclusions

This study identifies novel exosomal proteins associated with diverse functions, signaling pathways, and cell origins in ARDS lavage samples. These differentiated proteins may serve as regenerative niches for re-alveolarization in injured lungs.

Extracellular vesicles: pathogenic messengers and potential therapy for neonatal lung diseases

Extracellular vesicles (EVs) are a heterogeneous group of nano-sized membranous structures increasingly recognized as mediators of intercellular and inter-organ communication. EVs contain a cargo of proteins, lipids and nucleic acids, and their cargo composition is highly dependent on the biological function of the parental cells. Their cargo is protected from the extracellular environment by the phospholipid membrane, thus allowing for safe transport and delivery of their intact cargo to nearby or distant target cells, resulting in modification of the target cell's gene expression, signaling pathways and overall function. The highly selective, sophisticated network through which EVs facilitate cell signaling and modulate cellular processes make studying EVs a major focus of interest in understanding various biological functions and mechanisms of disease. Tracheal aspirate EV-miRNA profiling has been suggested as a potential biomarker for respiratory outcome in preterm infants and there is strong preclinical evidence showing that EVs released from stem cells protect the developing lung from the deleterious effects of hyperoxia and infection. This article will review the role of EVs as pathogenic messengers, biomarkers, and potential therapies for neonatal lung diseases.

SEVERE CORONAVIRUS DISEASE 2019: FROM PATHOGENESIS TO THERAPY

ABSTRACT

The COVID-19 pandemic has been a challenge to propose efficient therapies. Because severe SARS-CoV2 infection is a viral sepsis eventually followed by an immunological autoinflammatory phenomenon, many approaches have been inspired by the previous attempts made in bacterial sepsis, while specific antiviral strategies (use of interferon or specific drugs) have been additionally investigated. We summarize our current thinking on the use of SARS-CoV-2 antivirals, corticosteroids, anti-IL-1, anti-IL-6, anti-C5a, as well as stem cell therapy in severe COVID-19. Patient stratification and appropriate time window will be important to be defined to guide successful treatment.

Current status in cellular-based therapies for prevention and treatment of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the pathogen responsible for the coronavirus disease 2019 (COVID-19) outbreaks that resulted in a catastrophic threat to global health, with more than 500 million cases detected and 5.5 million deaths worldwide. Patients with a COVID-19 infection presented with clinical manifestations ranging from asymptomatic to severe symptoms, resulting in acute lung injury, acute respiratory distress syndrome, and even death. Immune dysregulation through delayed innate immune response or impairment of the adaptive immune response is the key contributor to the pathophysiology of COVID-19 and SARS-CoV-2-induced cytokine storm. Symptomatic and supportive therapy is the fundamental strategy in treating COVID-19 infection, including antivirals, steroid-based therapies, and cell-based immunotherapies. Various studies reported substantial effects of immune-based therapies for patients with COVID-19 to modulate the over-activated immune system while simultaneously refining the body's ability to destroy the virus. However, challenges may arise from the complexity of the disease through the genetic variance of the virus itself and patient heterogeneity, causing increased transmissibility and heightened immune system evasion that rapidly change the intervention and prevention measures for SARS-CoV-2. Cell-based therapy, utilizing stem cells, dendritic cells, natural killer cells, and T cells, among others, are being extensively explored as other potential immunological approaches for preventing and treating SARS-CoV-2-affected patients the similar process was effectively proven in SARS-CoV-1 and MERS-CoV infections. This review provides detailed insights into the innate and adaptive immune response-mediated cell-based immunotherapies in COVID-19 patients. The immune response linking towards engineered autologous or allogenic immune cells for either treatment or preventive therapies is subsequently highlighted in an individual study or in combination with several existing treatments. Up-to-date data on completed and ongoing clinical trials of cell-based agents for preventing or treating COVID-19 are also outlined to provide a guide that can help in treatment decisions and future trials.

What is the need and why is it time for innovative models for understanding lung repair and regeneration?

Advances in tissue engineering continue at a rapid pace and have provided novel methodologies and insights into normal cell and tissue homeostasis, disease pathogenesis, and new potential therapeutic strategies. The evolution of new techniques has particularly invigorated the field and span a range from novel organ and organoid technologies to increasingly sophisticated imaging modalities. This is particularly relevant for the field of lung biology and diseases as many lung diseases, including chronic obstructive pulmonary disease (COPD) and idiopathic fibrosis (IPF), among others, remain incurable with significant morbidity and mortality. Advances in lung regenerative medicine and engineering also offer new potential avenues for critical illnesses such as the acute respiratory distress syndrome (ARDS) which also continue to have significant morbidity and mortality. In this review, an overview of lung regenerative medicine with focus on current status of both structural and functional repair will be presented. This will serve as a platform for surveying innovative models and techniques for study, highlighting the need and timeliness for these approaches.

Circulating Myeloid Cell-derived Extracellular Vesicles as Mediators of Indirect Acute Lung Injury

Blood-borne myeloid cells, neutrophils and monocytes, play a central role in the development of indirect acute lung injury (ALI) during sepsis and noninfectious systemic inflammatory response syndrome. By contrast, the contribution of circulating myeloid cell-derived extracellular vesicles (EVs) to ALI is unknown, despite acute increases in their numbers during sepsis and systemic inflammatory response syndrome. Here, we investigated the direct role of circulating myeloid-EVs in ALI using a mouse isolated perfused lung system and a human cell coculture model of pulmonary vascular inflammation consisting of lung microvascular endothelial cells and peripheral blood mononuclear cells. Total and immunoaffinity-isolated myeloid (CD11b⁺) and platelet (CD41⁺) EVs were prepared from the plasma of intravenous LPS-injected endotoxemic donor mice and transferred directly into recipient lungs. Two-hour perfusion of lungs with unfractionated EVs from a single donor induced pulmonary edema formation and increased perfusate concentrations of RAGE (receptor for advanced glycation end products), consistent with lung injury. These responses were abolished in the lungs of monocyte-depleted mice. The isolated myeloid- but not platelet-EVs produced a similar injury response and the acute intravascular release of proinflammatory cytokines and endothelial injury markers. In the in vitro human coculture model, human myeloid- (CD11b⁺) but not platelet- (CD61⁺) EVs isolated from LPS-stimulated whole blood induced acute proinflammatory cytokine production and endothelial activation. These findings implicate circulating myeloid-EVs as acute mediators of pulmonary vascular inflammation and edema, suggesting an alternative therapeutic target for attenuation of indirect ALI.

Dexmedetomidine alleviates acute lung injury by promoting Tregs differentiation via activation of AMPK/SIRT1 pathway

OBJECTIVES

To explore the anti-inflammatory effect and the potential mechanism of dexmedetomidine in ARDS/ALI.

MATERIALS AND METHODS

C57BL/6 mice and EL-4 cells were used in this research. The ALI model was established by CLP. The level of inflammatory cytokines in the lung and blood, the severity of lung injury, the expression of Foxp3, and the proportion of Tregs were detected before and after dexmedetomidine treatment. The expression of the AMPK/SIRT1 after dexmedetomidine treatment was detected in vivo and in vitro. After blocking the AMPK/SIRT1 pathway or depleting Tregs in vivo, the level of the inflammatory response, tissue injury, and Tregs differentiation were detected again to clarify the effect of dexmedetomidine.

RESULTS

Dexmedetomidine significantly reduced systemic inflammation and lung injury in CLP mice. Dexmedetomidine enhanced the Foxp3 expression in the lungs and the frequency of Tregs in the spleen. Dexmedetomidine up-regulated the protein expression of p-AMPK and SIRT1 in lungs and EL-4 cells and facilitated the differentiation of naïve CD4⁺ T cells into Tregs in vitro. Meanwhile, DEX also increased the expression of Helios in Treg cells.

CONCLUSIONS

DEX could improve ARDS/ALI by facilitating the differentiation of Tregs from naïve CD4⁺ T cells via activating the AMPK/SIRT1 pathway.

Dual Role of Extracellular Vesicles in Sepsis-Associated Kidney and Lung Injury

Extracellular vesicles form a complex intercellular communication network, shuttling a variety of proteins, lipids, and nucleic acids, including regulatory RNAs, such as microRNAs. Transfer of these molecules to target cells allows for the modulation of sets of genes and mediates multiple paracrine and endocrine actions. EVs exert broad pro-inflammatory, pro-oxidant, and pro-apoptotic effects in sepsis, mediating microvascular dysfunction and multiple organ damage. This deleterious role is well documented in sepsis-associated acute kidney injury and acute respiratory distress syndrome. On the other hand, protective effects of stem cell-derived extracellular vesicles have been reported in experimental models of sepsis. Stem cell-derived extracellular vesicles recapitulate beneficial cytoprotective, regenerative, and immunomodulatory properties of parental cells and have shown therapeutic effects in experimental models of sepsis with kidney and lung involvement. Extracellular vesicles are also likely to play a role in deranged kidney-lung crosstalk, a hallmark of sepsis, and may be key to a better understanding of shared mechanisms underlying multiple organ dysfunction. In this review, we analyze the state-of-the-art knowledge on the dual role of EVs in sepsis-associated kidney/lung injury and repair. PubMed library was searched from inception to July 2022, using a combination of medical subject headings (MeSH) and keywords related to EVs, sepsis, acute kidney injury (AKI), acute lung injury (ALI), and acute respiratory distress syndrome (ARDS). Key findings are summarized into two sections on detrimental and beneficial mechanisms of actions of EVs in kidney and lung injury, respectively. The role of EVs in kidney-lung crosstalk is then outlined. Efforts to expand knowledge on EVs may pave the way to employ them as prognostic biomarkers or therapeutic targets to prevent or reduce organ damage in sepsis.

Mesenchymal stromal cells-derived extracellular vesicles reprogramme macrophages in ARDS models through the miR-181a-5p-PTEN-pSTAT5-SOCS1 axis

RATIONALE

A better understanding of the mechanism of action of mesenchymal stromal cells (MSCs) and their extracellular vesicles (EVs) is needed to support their use as novel therapies for acute respiratory distress syndrome (ARDS). Macrophages are important mediators of ARDS inflammatory response. Suppressor of cytokine signalling (SOCS) proteins are key regulators of the macrophage phenotype switch. We therefore investigated whether SOCS proteins are involved in mediation of the MSC effect on human macrophage reprogramming.

METHODS

Human monocyte-derived macrophages (MDMs) were stimulated with lipopolysaccharide (LPS) or plasma samples from patients with ARDS (these samples were previously classified into hypo-inflammatory and hyper-inflammatory phenotype) and treated with MSC conditioned medium (CM) or EVs. Protein expression was measured by Western blot. EV micro RNA (miRNA) content was determined by miRNA sequencing. In vivo: LPS-injured C57BL/6 mice were given EVs isolated from MSCs in which miR-181a had been silenced by miRNA inhibitor or overexpressed using miRNA mimic.

RESULTS

EVs were the key component of MSC CM responsible for anti-inflammatory modulation of human macrophages. EVs significantly reduced secretion of tumour necrosis factor-α and interleukin-8 by LPS-stimulated or ARDS plasma-stimulated MDMs and this was dependent on SOCS1. Transfer of miR-181a in EVs downregulated phosphatase and tensin homolog (PTEN) and subsequently activated phosphorylated signal transducer and activator of transcription 5 (pSTAT5) leading to upregulation of SOCS1 in macrophages. In vivo, EVs alleviated lung injury and upregulated pSTAT5 and SOCS1 expression in alveolar macrophages in a miR181-dependent manner. Overexpression of miR-181a in MSCs significantly enhanced therapeutic efficacy of EVs in this model.

CONCLUSION

miR-181a-PTEN-pSTAT5-SOCS1 axis is a novel pathway responsible for immunomodulatory effect of MSC EVs in ARDS.

Role of extracellular vesicles in lung diseases

ABSTRACT

Extracellular vesicles (EVs) are anuclear particles composed of lipid bilayers that contain nucleic acids, proteins, lipids, and organelles. EVs act as an important mediator of cell-to-cell communication by transmitting biological signals or components, including lipids, proteins, messenger RNAs, DNA, microRNAs, organelles, etc, to nearby or distant target cells to activate and regulate the function and phenotype of target cells. Under physiological conditions, EVs play an essential role in maintaining the homeostasis of the pulmonary milieu but they can also be involved in promoting the pathogenesis and progression of various respiratory diseases including chronic obstructive pulmonary disease, asthma, acute lung injury/acute respiratory distress syndrome, idiopathic pulmonary fibrosis (IPF), and pulmonary artery hypertension. In addition, in multiple preclinical studies, EVs derived from mesenchymal stem cells (EVs) have shown promising therapeutic effects on reducing and repairing lung injuries. Furthermore, in recent years, researchers have explored different methods for modifying EVs or enhancing EVs-mediated drug delivery to produce more targeted and beneficial effects. This article will review the characteristics and biogenesis of EVs and their role in lung homeostasis and various acute and chronic lung diseases and the potential therapeutic application of EVs in the field of clinical medicine.

Isolation of Extracellular Vesicles From the Bronchoalveolar Lavage Fluid of Healthy and Asthmatic Horses

Extracellular vesicles (EVs) are membrane-bound particles that engage in inflammatory reactions by mediating cell–cell interactions. Previously, EVs have been isolated from the bronchoalveolar lavage fluid (BALF) of humans and rodents. The aim of this study was to investigate the number and size distribution of EVs in the BALF of asthmatic horses (EA, n = 35) and healthy horses (n = 19). Saline was injected during bronchoscopy to the right lung followed by manual aspiration. The retrieved BALF was centrifuged twice to remove cells and biological debris. The supernatant was concentrated and EVs were isolated using size-exclusion chromatography. Sample fractions were measured with nanoparticle tracking analysis (NTA) for particle number and size, and transmission electron microscopy and confocal laser scanning microscopy were used to visualize EVs. The described method was able to isolate and preserve EVs. The mean EV size was 247 ± 35 nm (SD) in the EA horses and 261 ± 47 nm in the controls by NTA. The mean concentration of EVs was 1.38 × 10¹² ± 1.42 × 10¹² particles/mL in the EA horses and 1.33 × 10¹² ± 1.07 × 10¹² particles/mL in the controls with no statistically significant differences between the groups. With Western blotting and microscopy, these particles were documented to associate with EV protein markers (CD63, TSG101, HSP70, EMMPRIN, and actin) and hyaluronan. Equine BALF is rich in EVs of various sizes, and the described protocol is usable for isolating EVs. In the future, the role of EVs can be studied in horses with airway inflammation.

miR-142-5p Encapsulated by Serum-Derived Extracellular Vesicles Protects against Acute Lung Injury in Septic Rats following Remote Ischemic Preconditioning via the PTEN/PI3K/Akt Axis

This study intends to investigate the effects of miR-142-5p encapsulated by serum-derived extracellular vesicles (EVs) on septic acute lung injury (ALI) following remote ischemic preconditioning (RIPC) through a PTEN-involved mechanism. ALI was induced in rats by lipopolysaccharide (LPS) injection, 24 h before which RIPC was performed via the left lower limb. Next, the binding affinity between miR-142-5p and PTEN was identified. EVs were isolated from serum and injected into rats. The morphology of lung tissues, pulmonary edema, and inflammatory cell infiltration into lung tissues were then assessed, and TNF-α and IL-6 levels in serum and lung tissues were measured. The results indicated that RIPC could attenuate ALI in sepsis. miR-142-5p expression was increased in serum, lung tissues, and serum-derived EVs of ALI rats following RIPC. miR-142-5p could target PTEN to activate the PI3K/Akt signaling pathway. miR-142-5p shuttled by serum-derived EVs reduced pulmonary edema, neutrophil infiltration, and TNF-α and IL-6 levels, thus alleviating ALI in LPS-induced septic rats upon RIPC. Collectively, serum-derived EVs-loaded miR-142-5p downregulated PTEN and activated PI3K/Akt to inhibit ALI in sepsis following RIPC, thus highlighting potential therapeutic molecular targets against ALI in sepsis.

CD14-positive extracellular vesicles in bronchoalveolar lavage fluid as a new biomarker of acute respiratory distress syndrome

Recent studies have indicated that extracellular vesicles (EVs) may play a role in the pathogenesis of acute respiratory distress syndrome (ARDS). EVs have been identified as potential biomarkers of disease severity and prognosis in other pulmonary diseases. We sought to characterize the EV phenotype within bronchoalveolar lavage (BAL) fluid of patients with ARDS, and to determine whether BAL EV could be used as a potential biomarker in ARDS. BAL was collected from patients with sepsis with and without ARDS, and from esophagectomy patients postoperatively (of whom a subset later developed ARDS during hospital admission). BAL EVs were characterized with regard to size, number, and cell of origin. Patients with sepsis-related ARDS had significantly higher numbers of CD14⁺/CD81⁺ monocyte-derived BAL EV than patients with sepsis without ARDS (P = 0.015). However, the converse was observed in esophagectomy patients who later developed ARDS (P = 0.003). Esophagectomy patients who developed ARDS also had elevated CD31⁺/CD63⁺ and CD31⁺/CD81⁺ endothelial-derived BAL EV (P ≤ 0.02) compared with esophagectomy patients who did not develop ARDS. Further studies are required to determine whether CD31⁺ BAL EV may be a predictive biomarker for ARDS in esophagectomy patients. CD14⁺/CD81⁺ BAL EV numbers were significantly higher in those patients with sepsis-related ARDS who died during the 30 days following intensive care unit admission (P = 0.027). Thus, CD14⁺/CD81⁺ BAL EVs are a potential biomarker for disease severity and mortality in sepsis-related ARDS. These findings provide the impetus to further elucidate the contribution of these EVs to ARDS pathogenesis.

Extracellular Vesicles and Alveolar Epithelial-Capillary Barrier Disruption in Acute Respiratory Distress Syndrome: Pathophysiological Role and Therapeutic Potential

Extracellular vesicles (EVs) mediate intercellular communication by transferring genetic material, proteins and organelles between different cells types in both health and disease. Recent evidence suggests that these vesicles, more than simply diagnostic markers, are key mediators of the pathophysiology of acute respiratory distress syndrome (ARDS) and other lung diseases. In this review, we will discuss the contribution of EVs released by pulmonary structural cells (alveolar epithelial and endothelial cells) and immune cells in these diseases, with particular attention to their ability to modulate inflammation and alveolar-capillary barrier disruption, a hallmark of ARDS. EVs also offer a unique opportunity to develop new therapeutics for the treatment of ARDS. Evidences supporting the ability of stem cell-derived EVs to attenuate the lung injury and ongoing strategies to improve their therapeutic potential are also discussed.

The critical role of mesenchymal stromal/stem cell therapy in COVID-19 patients: An updated review

New coronavirus disease 2019 (COVID-19), as a pandemic disaster, has drawn the attention of researchers in various fields to discover suitable therapeutic approaches for the management of COVID-19 patients. Currently, there are many worries about the rapid spread of COVID-19; there is no approved treatment for this infectious disease, despite many efforts to develop therapeutic procedures for COVID-19. Emerging evidence shows that mesenchymal stromal/stem cell (MSC) therapy can be a suitable option for the management of COVID-19. These cells have many biological features (including the potential of differentiation, high safety and effectiveness, secretion of trophic factors and immunoregulatory features) that make them suitable for the treatment of various diseases. However, some studies have questioned the positive role of MSC therapy in the treatment of COVID-19. Accordingly, in this paper, we will focus on the therapeutic impacts of MSCs and their critical role in cytokine storm of COVID-19 patients.

Therapeutic effects of high molecular weight hyaluronic acid in severe Pseudomonas aeruginosa pneumonia in ex vivo perfused human lungs

We previously reported that extracellular vesicles (EVs) released during Escherichia coli (E. coli) bacterial pneumonia were inflammatory, and administration of high molecular weight hyaluronic acid (HMW HA) suppressed several indices of acute lung injury (ALI) from E. coli pneumonia by binding to these inflammatory EVs. The current study was undertaken to study the therapeutic effects of HMW HA in ex vivo perfused human lungs injured with Pseudomonas aeruginosa (PA)103 bacterial pneumonia. For lungs with baseline alveolar fluid clearance (AFC) <10%/h, HMW HA 1 or 2 mg was injected intravenously after 1 h (n = 4-9), and EVs released during PA pneumonia were collected from the perfusate over 6 h. For lungs with baseline AFC > 10%/h, HMW HA 2 mg was injected intravenously after 1 h (n = 6). In vitro experiments were conducted to evaluate the effects of HA on inflammation and bacterial phagocytosis. For lungs with AFC < 10%/h, administration of HMW HA intravenously significantly restored AFC and numerically decreased protein permeability and alveolar inflammation from PA103 pneumonia but had no effect on bacterial counts at 6 h. However, HMW HA improved bacterial phagocytosis by human monocytes and neutrophils and suppressed the inflammatory properties of EVs released during pneumonia on monocytes. For lungs with AFC > 10%/h, administration of HMW HA intravenously improved AFC from PA103 pneumonia but had no significant effects on protein permeability, inflammation, or bacterial counts. In the presence of impaired alveolar epithelial transport capacity, administration of HMW HA improved the resolution of pulmonary edema from Pseudomonas PA103 bacterial pneumonia.

Luteolin activates Tregs to promote IL-10 expression and alleviating caspase-11-dependent pyroptosis in sepsis-induced lung injury

OBJECTIVES

Acute respiratory distress syndrome (ARDS) is characterized by an excessive pulmonary inflammatory response. Pyroptosis is a newly form of programmed inflammatory cell death that is triggered by inflammatory caspases. Studies have shown that Luteolin has powerful anti-inflammation effects through activating the function of regulatory T cells (Tregs). The study aimed at investigating the effects of Luteolin on CLP-induced ALI.

METHODS

In our study, we employed the mouse cecal ligation and puncture (CLP) model to explore whether Luteolin contributed to alleviated lung injury in vivo. H&E staining and wet/dry (W/D) weight ratios were used to evaluate the severity of lung injury. The serum and BALF of cytokines were assessed by ELISA. The number of neutrophils in the BALF was counted. Immunohistochemistry of IL-10 and MPO in lung tissue was detected. The ROS level in lung was tested by ROS Assay Kit and expression of Gpx4 in lung tissue was detected by qRT-PCR and Western blotting. The regulatory T cells (Treg) population was analyzed in spleen and Peripheral blood mononuclear cells (PBMCs). The levels of caspase-11 protein, caspase-1 protein, GSDMD protein, IL-1α and IL-1β protein in the lung tissue was evaluated by Western blotting.

RESULTS

We found Luteolin significantly inhibits inflammation and attenuated CLP-induced lung injury in vivo, and the levels of, caspase-11, caspase-1, GSDMD, IL-1α and IL-1β protein in the lungs of CLP mice decreased significantly after pretreatment with Luteolin. Furthermore, the results showed that Luteolin could increase Treg frequencies and IL-10 levels in serum and BALF of CLP mice. It is noteworthy that depleting Tregs reverse Luteolin ameliorated lung injury, and IL-10 neutralizing antibodies treatment aggravated lung pyroptosis.

CONCLUSIONS

Our study illustrated that Luteolin contributed to alleviated lung injury, and attenuated caspase-11-dependent pyroptosis in the lung tissue of the CLP-induced ALI mouse model. The mechanisms could be related to regulating the frequency of Tregs and the levels of Treg derived IL-10. Treg cells were show to produce IL-10 and could alleviating caspase-11-dependent lung pyroptosis.

Nanomedicine for acute respiratory distress syndrome: The latest application, targeting strategy, and rational design

Acute respiratory distress syndrome (ARDS) is characterized by the severe inflammation and destruction of the lung air-blood barrier, leading to irreversible and substantial respiratory function damage. Patients with coronavirus disease 2019 (COVID-19) have been encountered with a high risk of ARDS, underscoring the urgency for exploiting effective therapy. However, proper medications for ARDS are still lacking due to poor pharmacokinetics, non-specific side effects, inability to surmount pulmonary barrier, and inadequate management of heterogeneity. The increased lung permeability in the pathological environment of ARDS may contribute to nanoparticle-mediated passive targeting delivery. Nanomedicine has demonstrated unique advantages in solving the dilemma of ARDS drug therapy, which can address the shortcomings and limitations of traditional anti-inflammatory or antioxidant drug treatment. Through passive, active, or physicochemical targeting, nanocarriers can interact with lung epithelium/endothelium and inflammatory cells to reverse abnormal changes and restore homeostasis of the pulmonary environment, thereby showing good therapeutic activity and reduced toxicity. This article reviews the latest applications of nanomedicine in pre-clinical ARDS therapy, highlights the strategies for targeted treatment of lung inflammation, presents the innovative drug delivery systems, and provides inspiration for strengthening the therapeutic effect of nanomedicine-based treatment.

Technological advances towards extracellular vesicles mass production

Extracellular vesicles (EVs) are becoming essential actors in bio-therapeutics, as much for their regenerative or immunomodulatory properties as for their potential as cargo delivery vehicles. To enable the democratization of these EV-based therapies, many challenges remain such as large-scale production which is necessary to reduce costs of treatment. Herein, we review some advanced works on high-yield EV manufacturing. One approach consists in developing large-scale cell culture platforms, while others focus on cell stimulation to increase particle yield per cell. This can be done by moderate physico-chemical stresses or by disrupting cell membrane towards autoassembled vesicle-like particles. We critically compare these different techniques, keeping in mind that the field still lacks shared characterization standards, underline the importance of therapeutic potency assessment and discuss mass production strategies that have been identified in current clinical trials.

Phospholipases A2 as biomarkers in ARDS

Acute respiratory distress syndrome (ARDS) is a multifactorial life-threatening lung injury, characterized by diffuse lung inflammation and increased alveolocapillary barrier permeability. The different stages of ARDS have distinctive biochemical and clinical profiles. Despite the progress of our understanding on ARDS pathobiology, the mechanisms underlying its pathogenesis are still obscure. Herein, we review the existing literature about the implications of phospholipases 2 (PLA2s), a large family of enzymes that catalyze the hydrolysis of fatty acids at the sn-2 position of glycerophospholipids, in ARDS-related pathology. We emphasize on the versatile way of participation of different PLA2s isoforms in the distinct ARDS subgroup phenotypes by either potentiating lung inflammation and damage or by preserving the normal lung. Current research supports that PLA2s are associated with the progression and the outcome of ARDS. We herein discuss the transcellular communication of PLA2s through secreted extracellular vesicles and suggest it as a new mechanism of PLA2s involvement in ARDS. Thus, the elucidation of the spatiotemporal features of PLA2s expression may give new insights and provide valuable information about the risk of an individual to develop ARDS or advance to more severe stages, and potentially identify PLA2 isoforms as biomarkers and target for pharmacological intervention.

Mesenchymal stromal cell extracellular vesicles rescue mitochondrial dysfunction and improve barrier integrity in clinically relevant models of ARDS

Alveolar epithelial–capillary barrier disruption is a hallmark of acute respiratory distress syndrome (ARDS). Contribution of mitochondrial dysfunction to the compromised alveolar-capillary barrier in ARDS remains unclear. Mesenchymal stromal cells-derived extracellular vesicles (MSC-EVs) are considered as a cell-free therapy for ARDS. Mitochondrial transfer was shown to be important for the therapeutic effects of MSCs and MSC-EVs. Here we investigated the contribution of mitochondrial dysfunction to the injury of alveolar epithelial and endothelial barriers in ARDS and the ability of MSC-EVs to modulate alveolar–capillary barrier integrity through mitochondrial transfer.

Primary human small airway epithelial and pulmonary microvascular endothelial cells and human precision cut lung slices (PCLSs) were stimulated with endotoxin or plasma samples from patients with ARDS and treated with MSC-EVs, barrier properties and mitochondrial functions were evaluated. Lipopolysaccharide (LPS)-injured mice were treated with MSC-EVs and degree of lung injury and mitochondrial respiration of the lung tissue were assessed.

Inflammatory stimulation resulted in increased permeability coupled with pronounced mitochondrial dysfunction in both types of primary cells and PCLSs. Extracellular vesicles derived from normal MSCs restored barrier integrity and normal levels of oxidative phosphorylation while an extracellular vesicles preparation which did not contain mitochondria was not effective. In vivo, presence of mitochondria was critical for extracellular vesicles ability to reduce lung injury and restore mitochondrial respiration in the lung tissue.

In the ARDS environment, MSC-EVs improve alveolar–capillary barrier properties through restoration of mitochondrial functions at least partially via mitochondrial transfer.

This study demonstrates that mitochondrial dysfunction is an important mechanism of ARDS pathogenesis. Mitochondrial transfer is crucial for the ability of MSC extracellular vesicles to restore integrity of the alveolar–capillary barrier.https://bit.ly/2JuqoCY

Updates on clinical trials evaluating the regenerative potential of allogenic mesenchymal stem cells in COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected nearly 118 million people and caused ~2.6 million deaths worldwide by early 2021, during the coronavirus disease 2019 (COVID-19) pandemic. Although the majority of infected patients show mild-to-moderate symptoms, a small fraction of patients develops severe symptoms. Uncontrolled cytokine production and the lack of substantive adaptive immune response result in hypoxia, acute respiratory distress syndrome (ARDS), or multiple organ failure in severe COVID-19 patients. Since the current standard of care treatment is insufficient to alleviate severe COVID-19 symptoms, many clinics have been prompted to perform clinical trials involving the infusion of mesenchymal stem cells (MSCs) due to their immunomodulatory and therapeutic properties. Several phases I/II clinical trials involving the infusion of allogenic MSCs have been performed last year. The focus of this review is to critically evaluate the safety and efficacy outcomes of the most recent, placebo-controlled phase I/II clinical studies that enrolled a larger number of patients, in order to provide a statistically relevant and comprehensive understanding of MSC's therapeutic potential in severe COVID-19 patients. Clinical outcomes obtained from these studies clearly indicate that: (i) allogenic MSC infusion in COVID-19 patients with ARDS is safe and effective enough to decreases a set of inflammatory cytokines that may drive COVID-19 associated cytokine storm, and (ii) MSC infusion efficiently improves COVID-19 patient survival and reduces recovery time. These findings strongly support further investigation into MSC-infusion in larger clinical trials for COVID-19 patients with ARDS, who currently have a nearly 50% of mortality rate.

Exosomes contribution in COVID-19 patients' treatment

Adipose cell-free derivatives have been recently gaining attention as potential therapeutic agents for various human diseases. In this context, mesenchymal stromal/stem cells (MSCs), adipocyte mesenchymal stem cells (Ad-MSCs) and adipose-derived stem cells (ADSC) possessing potent immunomodulatory activities are proposed as a therapeutic option for the treatment of coronavirus disease 2019 (COVID-19). The COVID-19 represents a global concern of public health caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in which there is not actually any specific therapy. MSCs exert an immunomodulation effect due to the secretion of endogenous factors, such as vascular endothelial growth factor (VEGF), insulin growth factor (IGF), and nerve growth factor (NGF), transforming growth factor (TGF)-β and growth differentiation factor (GDF)-11. Recent reports are promising for further studies and clinical applications of ADSCs and Ad-MSCs in COVID-19 patients. Experimental and clinical studies are exploring the therapeutic potential of both MSCs and derived-exosomes in moderating the morbidity and mortality of COVID-19. In this field, more preclinical and clinical studies are warranted to find an effective treatment for the patients suffering from COVID-19 infection.

Stem cell therapies and benefaction of somatic cell nuclear transfer cloning in COVID-19 era

BACKGROUND

The global health emergency of COVID-19 has necessitated the development of multiple therapeutic modalities including vaccinations, antivirals, anti-inflammatory, and cytoimmunotherapies, etc. COVID-19 patients suffer from damage to various organs and vascular structures, so they present multiple health crises. Mesenchymal stem cells (MSCs) are of interest to treat acute respiratory distress syndrome (ARDS) caused by SARS-CoV-2 infection.

MAIN BODY

Stem cell-based therapies have been verified for prospective benefits in copious preclinical and clinical studies. MSCs confer potential benefits to develop various cell types and organoids for studying virus-human interaction, drug testing, regenerative medicine, and immunomodulatory effects in COVID-19 patients. Apart from paving the ways to augment stem cell research and therapies, somatic cell nuclear transfer (SCNT) holds unique ability for a wide range of health applications such as patient-specific or isogenic cells for regenerative medicine and breeding transgenic animals for biomedical applications. Being a potent cell genome-reprogramming tool, the SCNT has increased prominence of recombinant therapeutics and cellular medicine in the current era of COVID-19. As SCNT is used to generate patient-specific stem cells, it avoids dependence on embryos to obtain stem cells.

CONCLUSIONS

The nuclear transfer cloning, being an ideal tool to generate cloned embryos, and the embryonic stem cells will boost drug testing and cellular medicine in COVID-19.

Microvesicles released from pneumolysin-stimulated lung epithelial cells carry mitochondrial cargo and suppress neutrophil oxidative burst

Microvesicles (MVs) are cell-derived extracellular vesicles that have emerged as markers and mediators of acute lung injury (ALI). One of the most common pathogens in pneumonia-induced ALI is Streptococcus pneumoniae (Spn), but the role of MVs during Spn lung infection is largely unknown. In the first line of defense against Spn and its major virulence factor, pneumolysin (PLY), are the alveolar epithelial cells (AEC). In this study, we aim to characterize MVs shed from PLY-stimulated AEC and explore their contribution in mediating crosstalk with neutrophils. Using in vitro cell and ex vivo (human lung tissue) models, we demonstrated that Spn in a PLY-dependent manner stimulates AEC to release increased numbers of MVs. Spn infected mice also had higher levels of epithelial-derived MVs in their alveolar compartment compared to control. Furthermore, MVs released from PLY-stimulated AEC contain mitochondrial content and can be taken up by neutrophils. These MVs then suppress the ability of neutrophils to produce reactive oxygen species, a critical host-defense mechanism. Taken together, our results demonstrate that AEC in response to pneumococcal PLY release MVs that carry mitochondrial cargo and suggest that these MVs regulate innate immune responses during lung injury.

Cerium oxide nanoparticle delivery of microRNA-146a for local treatment of acute lung injury

Acute respiratory distress syndrome (ARDS) is a devastating pulmonary disease with significant in-hospital mortality and is the leading cause of death in COVID-19 patients. Excessive leukocyte recruitment, unregulated inflammation, and resultant fibrosis contribute to poor ARDS outcomes. Nanoparticle technology with cerium oxide nanoparticles (CNP) offers a mechanism by which unstable therapeutics such as the anti-inflammatory microRNA-146a can be locally delivered to the injured lung without systemic uptake. In this study, we evaluated the potential of the radical scavenging CNP conjugated to microRNA-146a (termed CNP-miR146a) in preventing acute lung injury (ALI) following exposure to bleomycin. We have found that intratracheal delivery of CNP-miR146a increases pulmonary levels of miR146a without systemic increases, and prevents ALI by altering leukocyte recruitment, reducing inflammation and oxidative stress, and decreasing collagen deposition, ultimately improving pulmonary biomechanics.

Enoxaparin Attenuates Acute Lung Injury and Inflammasome Activation after Traumatic Brain Injury

Traumatic brain injury (TBI) patients frequently develop cardiopulmonary system complications such as acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). However, the mechanism by which TBI causes ALI/ARDS is not fully understood. Here, we used a severe TBI model to examine the effects of a low-molecular-weight heparin, enoxaparin, on inflammasome activation and lung injury damage. We investigated whether enoxaparin inhibits ALI and inflammasome signaling protein expression in the brain and lungs after TBI in mice. C57/BL6 mice were subjected to severe TBI and were treated with vehicle or 1 mg/kg of enoxaparin 30 min after injury. Lung and brain tissue were collected 24 h post-TBI and were analyzed by immunoblotting for expression of the inflammasome proteins, caspase-1 and interleukin (IL)-1β. In addition, lung tissue was collected for histological analysis to determine ALI scoring and neutrophil and macrophage infiltration post-injury. Our data show that severe TBI induces increased expression of inflammasome proteins caspase-1 and IL-1β in the brain and lungs of mice after injury. Treatment with enoxaparin attenuated inflammasome expression in the brain and lungs 24 h after injury. Enoxaparin significantly decreased ALI score as well as neutrophil and macrophage infiltration in lungs at 24 h after injury. This study demonstrates that enoxaparin attenuates ALI and inhibits inflammasome expression in the brain and lungs after TBI. These findings support the hypothesis that inhibition of the neural-respiratory inflammasome axis that is activated after TBI may have therapeutic potential.

MicroRNA-574-5p Attenuates Acute Respiratory Distress Syndrome by Targeting HMGB1

Acute respiratory distress syndrome (ARDS) is a critical condition with high mortality. HMGB1 (high-mobility group protein B1) is one of the key proinflammatory factors in the ARDS “inflammatory storm.” According to previous studies, some microRNAs (miRNAs) play important roles in this process. We aimed to determine the contributing miRNAs targeting the expression and release of HMGB1. miRNA expression in the peripheral blood of patients with ARDS was measured by miRNA microarray. miRNAs targeting HMGB1 were screened and explored for further study. In LPS-induced cell and mouse ARDS models, we explored the effect of this miRNA on the expression and secretion of HMGB1 by Western blot, real-time qPCR, and ELISA. The effects of this miRNA on the NF-κB signaling pathway, proinflammatory cytokines, and NLRP3 (nod-like receptor protein 3) inflammasome were detected by Western blot and real-time qPCR. In ARDS models, microRNA-574-5p (miR-574-5p) expression could be induced by the TLR4/NF-κB pathway upon LPS stimulation. It could suppress the inflammatory response by targeting HMGB1. Enforcing the expression of miR-574-5p or HMGB1 siRNA silencing inhibits the activation of NF-κB signaling pathway and the NLRP3 inflammasome. Moreover, overexpression of HMGB1 reversed the antiinflammatory effect of miR-574-5p. In ARDS mice, overexpression of miR-574-5p suppresses alveolar leukocytes infiltration, interstitial edema, protein effusion, and inflammation. This study demonstrated that miR-574-5p provided negative feedback to LPS-induced inflammation and relieved ARDS. It may provide new therapeutic strategies for ARDS.

Assessment of Alveolar Macrophage Dysfunction Using an in vitro Model of Acute Respiratory Distress Syndrome

Background: Impaired alveolar macrophage (AM) efferocytosis may contribute to acute respiratory distress syndrome (ARDS) pathogenesis; however, studies are limited by the difficulty in obtaining primary AMs from patients with ARDS. Our objective was to determine whether an in vitro model of ARDS can recapitulate the same AM functional defect observed in vivo and be used to further investigate pathophysiological mechanisms. Methods: AMs were isolated from the lung tissue of patients undergoing lobectomy and then treated with pooled bronchoalveolar lavage (BAL) fluid previously collected from patients with ARDS. AM phenotype and effector functions (efferocytosis and phagocytosis) were assessed by flow cytometry. Rac1 gene expression was assessed using quantitative real-time PCR. Results: ARDS BAL treatment of AMs decreased efferocytosis (p = 0.0006) and Rac1 gene expression (p = 0.016); however, bacterial phagocytosis was preserved. Expression of AM efferocytosis receptors MerTK (p = 0.015) and CD206 (p = 0.006) increased, whereas expression of the antiefferocytosis receptor SIRPα decreased following ARDS BAL treatment (p = 0.036). Rho-associated kinase (ROCK) inhibition partially restored AM efferocytosis in an in vitro model of ARDS (p = 0.009). Conclusions: Treatment of lung resection tissue AMs with ARDS BAL fluid induces impairment in efferocytosis similar to that observed in patients with ARDS. However, AM phagocytosis is preserved following ARDS BAL treatment. This specific impairment in AM efferocytosis can be partially restored by inhibition of ROCK. This in vitro model of ARDS is a useful tool to investigate the mechanisms by which the inflammatory alveolar microenvironment of ARDS induces AM dysfunction.

Inflammasome activation in acute lung injury

Inflammasomes are multiprotein complexes tasked with sensing endogenous or exogenous inflammatory signals and integrating this signal into a downstream response. Inflammasome activation has been implicated in a variety of pulmonary diseases, including pulmonary hypertension, bacterial pneumonia, COPD, and asthma. Of increasing interest is the contribution of inflammasome activation in the context of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). Inflammasome activation in both the lung parenchyma and resident immune cells generates intereukin-1β (IL-1β) and IL-18, both of which drive the cascade of lung inflammation forward. Blockade of these responses has been shown to be beneficial in animal models and is a focus of translational research in the field. In this review, we will discuss the assembly and regulation of inflammasomes during lung inflammation, highlighting therapeutically viable effector steps. We will examine the importance of IL-1β and IL-18, two key products of inflammasome activation, in ALI, as well as the contribution of the pulmonary endothelial cell to this process. Finally, we will explore translational research moving toward anti-inflammasome therapies for ALI/ARDS and speculate toward future directions for the field.

Liver-lung axes in alcohol-related liver disease

Alcohol-related liver disease (ALD) and alcohol-related susceptibility to acute lung injury are the leading causes of morbidity and mortality due to chronic alcohol abuse. Most commonly, alcohol-induced injury to both organs are evaluated independently, although they share many parallel mechanisms of injury. Moreover, recent studies indicate that there is a potential liver lung axis that may contribute to organ pathology. This mini-review explores established and potential mechanisms of organ-organ crosstalk in ALD and alcohol-related lung injury.

International Society for Extracellular Vesicles and International Society for Cell and Gene Therapy statement on extracellular vesicles from mesenchymal stromal cells and other cells: considerations for potential therapeutic agents to suppress coronavirus disease-19

STATEMENT

The International Society for Cellular and Gene Therapies (ISCT) and the International Society for Extracellular Vesicles (ISEV) recognize the potential of extracellular vesicles (EVs, including exosomes) from mesenchymal stromal cells (MSCs) and possibly other cell sources as treatments for COVID-19. Research and trials in this area are encouraged. However, ISEV and ISCT do not currently endorse the use of EVs or exosomes for any purpose in COVID-19, including but not limited to reducing cytokine storm, exerting regenerative effects or delivering drugs, pending the generation of appropriate manufacturing and quality control provisions, pre-clinical safety and efficacy data, rational clinical trial design and proper regulatory oversight.

Mesenchymal Stem/Stromal Cells Therapy for Sepsis and Acute Respiratory Distress Syndrome

Sepsis and acute respiratory distress syndrome (ARDS) constitute devastating conditions with high morbidity and mortality. Sepsis results from abnormal host immune response, with evidence for both pro- and anti-inflammatory activation present from the earliest phases. The "proinflammatory" response predominates initially causing host injury, with later-phase sepsis characterized by immune cell hypofunction and opportunistic superinfection. ARDS is characterized by inflammation and disruption of the alveolar-capillary membrane leading to injury and lung dysfunction. Sepsis is the most common cause of ARDS. Approximately 20% of deaths worldwide in 2017 were due to sepsis, while ARDS occurs in over 10% of all intensive care unit patients and results in a mortality of 30 to 45%. Given the fact that sepsis and ARDS share some-but not all-underlying pathophysiologic injury mechanisms, the lack of specific therapies, and their frequent coexistence in the critically ill, it makes sense to consider therapies for both conditions together. In this article, we will focus on the therapeutic potential of mesenchymal stem/stromal cells (MSCs). MSCs are available from several tissues, including bone marrow, umbilical cord, and adipose tissue. Allogeneic administration is feasible, an important advantage for acute conditions like sepsis or ARDS. They possess diverse mechanisms of action of relevance to sepsis and ARDS, including direct and indirect antibacterial actions, potent effects on the innate and adaptive response, and pro-reparative effects. MSCs can be preactivated thereby potentiating their effects, while the use of their extracellular vesicles can avoid whole cell administration. While early-phase clinical trials suggest safety, considerable challenges exist in moving forward to phase III efficacy studies, and to implementation as a therapy should they prove effective.