Stem cell derived exosomes-based therapy for acute lung injury and acute respiratory distress syndrome: A novel therapeutic strategy

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.

Therapeutic efficacy of thrombin-preconditioned mesenchymal stromal cell-derived extracellular vesicles on Escherichia coli-induced acute lung injury in mice

BACKGROUND

Acute lung injury (ALI) following pneumonia involves uncontrolled inflammation and tissue injury, leading to high mortality. We previously confirmed the significantly increased cargo content and extracellular vesicle (EV) production in thrombin-preconditioned human mesenchymal stromal cells (thMSCs) compared to those in naïve and other preconditioning methods. This study aimed to investigate the therapeutic efficacy of EVs derived from thMSCs in protecting against inflammation and tissue injury in an Escherichia coli (E. coli)-induced ALI mouse model.

METHODS

In vitro, RAW 264.7 cells were stimulated with 0.1 µg/mL liposaccharides (LPS) for 1 h, then were treated with either PBS (LPS Ctrl) or 5 × 107 particles of thMSC-EVs (LPS + thMSC-EVs) for 24 h. Cells and media were harvested for flow cytometry and ELISA. In vivo, ICR mice were anesthetized, intubated, administered 2 × 107 CFU/100 µl of E. coli. 50 min after, mice were then either administered 50 µL saline (ECS) or 1 × 109 particles/50 µL of thMSC-EVs (EME). Three days later, the therapeutic efficacy of thMSC-EVs was assessed using extracted lung tissue, bronchoalveolar lavage fluid (BALF), and in vivo computed tomography scans. One-way analysis of variance with post-hoc TUKEY test was used to compare the experimental groups statistically.

RESULTS

In vitro, IL-1β, CCL-2, and MMP-9 levels were significantly lower in the LPS + thMSC-EVs group than in the LPS Ctrl group. The percentages of M1 macrophages in the normal control, LPS Ctrl, and LPS + thMSC-EV groups were 12.5, 98.4, and 65.9%, respectively. In vivo, the EME group exhibited significantly lower histological scores for alveolar congestion, hemorrhage, wall thickening, and leukocyte infiltration than the ECS group. The wet-dry ratio for the lungs was significantly lower in the EME group than in the ECS group. The BALF levels of CCL2, TNF-a, and IL-6 were significantly lower in the EME group than in the ECS group. In vivo CT analysis revealed a significantly lower percentage of damaged lungs in the EME group than in the ECS group.

CONCLUSION

Intratracheal thMSC-EVs administration significantly reduced E. coli-induced inflammation and lung tissue damage. Overall, these results suggest therapeutically enhanced thMSC-EVs as a novel promising therapeutic option for ARDS/ALI.

INDUCED PLURIPOTENT STEM CELL-DERIVED MESENCHYMAL STEM CELLS-DERIVED EXTRACELLULAR VESICLES ATTENUATE LPS-INDUCED LUNG INJURY AND ENDOTOXEMIA IN MICE

ABSTRACT

Introduction: We hypothesized extracellular vesicles (EVs) from preconditioned human-induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs) attenuate LPS-induced acute lung injury (ALI) and endotoxemia. Methods: iMSCs were incubated with cell stimulation cocktail (CSC) and EVs were isolated. iMSC-EVs were characterized by size and EV markers. Biodistribution of intratracheal (IT), intravenous, and intraperitoneal injection of iMSC-EVs in mice was examined using IVIS. Uptake of iMSC-EVs in lung tissue, alveolar macrophages, and RAW264.7 cells was also assessed. C57BL/6 mice were treated with IT/IP iMSC-EVs or vehicle ± IT/IP LPS to induce ALI/acute respiratory distress syndrome and endotoxemia. Lung tissues, plasma, and bronchoalveolar lavage fluid (BALF) were harvested at 24 h. Lung histology, BALF neutrophil/macrophage, cytokine levels, and total protein concentration were measured to assess ALI and inflammation. Survival studies were performed using IP LPS in mice for 3 days. Results: iMSC-EV route of administration resulted in differential tissue distribution. iMSC-EVs were taken up by alveolar macrophages in mouse lung and cultured RAW264.7 cells. IT LPS-treated mice demonstrated marked histologic ALI, increased BALF neutrophils/macrophages and protein, and increased BALF and plasma TNF-α/IL-6 levels. These parameters were attenuated by 2 h before or 2 h after treatment with IT iMSC-EVs in ALI mice. Interestingly, the IT LPS-induced increase in IL-10 was augmented by iMSC-EVs. Mice treated with IP LPS showed increases in TNF-α and IL-6 that were downregulated by iMSC-EVs and LPS-induced mortality was ameliorated by iMSC-EVs. Administration of IT iMSC-EVs 2 h after LPS downregulated the increase in proinflammatory cytokines (TNF-α/IL-6) by LPS and further increased IL-10 levels. Conclusions: iMSC-EVs attenuate the inflammatory effects of LPS on cytokine levels in ALI and IP LPS in mice. LPS-induced mortality was improved with administration of iMSC-EVs.

A large-scale production of mesenchymal stem cells and their exosomes for an efficient treatment against lung inflammation

Mesenchymal stem cells (MSCs) and their produced exosomes have demonstrated inherent capabilities of inflammation-guided targeting and inflammatory modulation, inspiring their potential applications as biologic agents for inflammatory treatments. However, the clinical applications of stem cell therapies are currently restricted by several challenges, and one of them is the mass production of stem cells to satisfy the therapeutic demands in the clinical bench. Herein, a production of human amnion-derived MSCs (hMSCs) at a scale of over 1 × 109 cells per batch was reported using a three-dimensional (3D) culture technology based on microcarriers coupled with a spinner bioreactor system. The present study revealed that this large-scale production technology improved the inflammation-guided migration and the inflammatory suppression of hMSCs, without altering their major properties as stem cells. Moreover, these large-scale produced hMSCs showed an efficient treatment against the lipopolysaccharide (LPS)-induced lung inflammation in mice models. Notably, exosomes collected from these large-scale produced hMSCs were observed to inherit the efficient inflammatory suppression capability of hMSCs. The present study showed that 3D culture technology using microcarriers coupled with a spinner bioreactor system can be a promising strategy for the large-scale expansion of hMSCs with improved anti-inflammation capability, as well as their secreted exosomes.

The physiological phenomenon and regulation of macrophage polarization in diabetic wound

Macrophages play a crucial role in regulating wound healing, as they undergo a transition from the proinflammatory M1 phenotype to the proliferative M2 phenotype, ultimately contributing to a favorable outcome. However, in hyperglycemic and hyper-reactive oxygen species environments, the polarization of macrophages becomes dysregulated, hindering the transition from the inflammatory to proliferative phase and consequently delaying the wound healing process. Consequently, regulating macrophage polarization is often regarded as a potential target for the treatment of diabetic wounds. The role of macrophages in wound healing and the changes in macrophages in diabetic conditions were discussed in this review. After that, we provide a discussion of recent therapeutic strategies for diabetic wounds that utilize macrophage polarization. Furthermore, this review also provides a comprehensive summary of the efficacious treatment strategies aimed at enhancing diabetic wound healing through the regulation of macrophage polarization. By encompassing a thorough understanding of the fundamental principles and their practical implementation, the advancement of treatment strategies for diabetic wounds can be further facilitated.

Bone Mesenchymal Stem Cell-Derived Small Extracellular Vesicles Ameliorated Lipopolysaccharide-Induced Lung Injury Via the miR-21-5p/PCSK6 Pathway

Acute lung injury (ALI) is a life-threatening disease that currently lacks a cure. Although stem cell-derived small extracellular vesicles (sEVs) have shown promising effects in the treatment of ALI, their underlying mechanisms and responsible components have yet to be identified. Proprotein convertase subtilisin/kexin type 6 (PCSK6) is a gene involved in inflammation and a potential target of miR-21-5p, a microRNA enriched in stem cell-derived sEVs. The current study investigated the role of PCSK6 in lipopolysaccharide (LPS)-induced ALI and its interaction with miR-21-5p. Notably, our results showed that PCSK6 expression was positively correlated with LPS stimulation. Knockdown of PCSK6 ameliorated LPS-induced inhibition of proliferation and upregulation of permeability in human BEAS-2B cells, whereas PCSK6 overexpression displayed the opposite effects. BEAS-2B cells were able to actively internalize the cocultured bone mesenchymal stem cell (MSC)-derived sEVs (BMSC-sEVs), which alleviated the cell damage caused by LPS. Overexpressing PCSK6, however, eliminated the therapeutic effects of BMSC-sEV coculture. Mechanistically, BMSC-sEVs inhibited PCSK6 expression via the delivery of miR-21-5p, which is directly bound to the PCSK6 gene. Our work provides evidence for the role of PCSK6 in LPS-induced ALI and identified miR-21-5p as a component of BMSC-derived sEVs that suppressed PCSK6 expression and ameliorated LPS-induced cell damage. These results reveal a novel molecular mechanism for ALI pathogenesis and highlight the therapeutic potential of using sEVs released by stem cells to deliver miR-21-5p for ALI treatment.

Host and Pathogen-Directed Therapies against Microbial Infections Using Exosome- and Antimicrobial Peptide-derived Stem Cells with a Special look at Pulmonary Infections and Sepsis

Microbial diseases are a great threat to global health and cause considerable mortality and extensive economic losses each year. The medications for treating this group of diseases (antibiotics, antiviral, antifungal drugs, etc.) directly attack the pathogenic agents by recognizing the target molecules. However, it is necessary to note that excessive use of any of these drugs can lead to an increase in microbial resistance and infectious diseases. New therapeutic methods have been studied recently using emerging drugs such as mesenchymal stem cell-derived exosomes (MSC-Exos) and antimicrobial peptides (AMPs), which act based on two completely different strategies against pathogens including Host-Directed Therapy (HDT) and Pathogen-Directed Therapy (PDT), respectively. In the PDT approach, AMPs interact directly with pathogens to interrupt their intrusion, survival, and proliferation. These drugs interact directly with the cell membrane or intracellular components of pathogens and cause the death of pathogens or inhibit their replication. The mechanism of action of MSC-Exos in HDT is based on immunomodulation and regulation, promotion of tissue regeneration, and reduced host toxicity. This review studies the potential of mesenchymal stem cell-derived exosomes/ATPs therapeutic properties against microbial infectious diseases especially pulmonary infections and sepsis.

The capacity of exosomes derived from adipose-derived stem cells to enhance wound healing in diabetes

The slow healing and nonhealing of diabetic wounds have long posed challenges for clinical practitioners. In the presence of elevated glucose levels, the body's regulatory mechanisms undergo alterations that impede normal wound healing processes, including cell proliferation, cytokine release, and growth factor activity. Consequently, the advancement of stem cell technology has sparked growing interest in utilizing stem cells and their derivatives as potential therapeutic agents to enhance diabetic wound healing. This paper aims to provide an academic review of the therapeutic effects of adipose-derived stem cell-EXOs (ADSC-EXOs) in diabetic wound healing. As a cell-free therapy, exosomes (EXOs) possess a multitude of proteins and growth factors that have been shown to be advantageous in promoting wound healing and mitigating the potential risks associated with stem cell therapy. By examining the current knowledge on ADSC-EXOs, this review seeks to offer insights and guidance for the potential application of EXOs in the treatment of diabetic wounds.

Human placenta-derived mesenchymal stem cell administration protects against acute lung injury in a mouse model

This study aims to investigate the effect of placenta-derived mesenchymal stem cells (PMSCs) administration on tissue repair following acute lung injury (ALI). PMSCs were transplanted intravenously to a mouse model of lipopolysaccharide-induced ALI. The therapeutic effects were determined by evaluating several indicators, including pathology; the wet/dry ratio of the lungs; blood gas analysis; the total protein content, cell numbers, and the activity of myeloperoxidase (MPO) in bronchial alveolar lavage fluid (BALF); and the levels of anti-inflammatory and proinflammatory cytokines in serum and BALF. To investigate the underlying mechanism, PMSC-derived exosomes were used for ALI treatment. Administration of PMSCs improved the degree of lung injury, reduced inflammation, increased the expression levels of anti-inflammatory cytokines, and protected lung function. As expected, the effects of PMSC-derived exosomes in the ALI model were similar to those of PMSCs, both in terms of improved lung function and reduced inflammation. These findings suggest that PMSCs have ameliorating effects on ALI that are potentially mediated via their secreted exosomes.

Advances of mesenchymal stem cells and their derived extracellular vesicles as a promising therapy for acute respiratory distress syndrome: from bench to clinic

Acute respiratory distress syndrome (ARDS) is an acute inflammatory lung injury characterized by diffuse alveolar damage. The period prevalence of ARDS was 10.4% of ICU admissions in 50 countries. Although great progress has been made in supportive care, the hospital mortality rate of severe ARDS is still up to 46.1%. Moreover, up to now, there is no effective pharmacotherapy for ARDS and most clinical trials focusing on consistently effective drugs have met disappointing results. Mesenchymal stem cells (MSCs) and their derived extracellular vesicles (EVs) have spawned intense interest of a wide range of researchers and clinicians due to their robust anti-inflammatory, anti-apoptotic and tissue regeneration properties. A growing body of evidence from preclinical studies confirmed the promising therapeutic potential of MSCs and their EVs in the treatment of ARDS. Based on the inspiring experimental results, clinical trials have been designed to evaluate safety and efficacy of MSCs and their EVs in ARDS patients. Moreover, trials exploring their optimal time window and regimen of drug administration are ongoing. Therefore, this review aims to present an overview of the characteristics of mesenchymal stem cells and their derived EVs, therapeutic mechanisms for ARDS and research progress that has been made over the past 5 years.

Delivery systems of therapeutic nucleic acids for the treatment of acute lung injury/acute respiratory distress syndrome

Acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS) is a devastating inflammatory lung disease with a high mortality rate. ALI/ARDS is induced by various causes, including sepsis, infections, thoracic trauma, and inhalation of toxic reagents. Corona virus infection disease-19 (COVID-19) is also a major cause of ALI/ARDS. ALI/ARDS is characterized by inflammatory injury and increased vascular permeability, resulting in lung edema and hypoxemia. Currently available treatments for ALI/ARDS are limited, but do include mechanical ventilation for gas exchange and treatments supportive of reduction of severe symptoms. Anti-inflammatory drugs such as corticosteroids have been suggested, but their clinical effects are controversial with possible side-effects. Therefore, novel treatment modalities have been developed for ALI/ARDS, including therapeutic nucleic acids. Two classes of therapeutic nucleic acids are in use. The first constitutes knock-in genes for encoding therapeutic proteins such as heme oxygenase-1 (HO-1) and adiponectin (APN) at the site of disease. The other is oligonucleotides such as small interfering RNAs and antisense oligonucleotides for knock-down expression of target genes. Carriers have been developed for efficient delivery for therapeutic nucleic acids into the lungs based on the characteristics of the nucleic acids, administration routes, and targeting cells. In this review, ALI/ARDS gene therapy is discussed mainly in terms of delivery systems. The pathophysiology of ALI/ARDS, therapeutic genes, and their delivery strategies are presented for development of ALI/ARDS gene therapy. The current progress suggests that selected and appropriate delivery systems of therapeutic nucleic acids into the lungs may be useful for the treatment of ALI/ARDS.

miR-223: a key regulator of pulmonary inflammation

Small noncoding RNAs, known as microRNAs (miRNAs), are vital for the regulation of diverse biological processes. miR-223, an evolutionarily conserved anti-inflammatory miRNA expressed in cells of the myeloid lineage, has been implicated in the regulation of monocyte-macrophage differentiation, proinflammatory responses, and the recruitment of neutrophils. The biological functions of this gene are regulated by its expression levels in cells or tissues. In this review, we first outline the regulatory role of miR-223 in granulocytes, macrophages, endothelial cells, epithelial cells and dendritic cells (DCs). Then, we summarize the possible role of miR-223 in chronic obstructive pulmonary disease (COPD), acute lung injury (ALI), coronavirus disease 2019 (COVID-19) and other pulmonary inflammatory diseases to better understand the molecular regulatory networks in pulmonary inflammatory diseases.

Engineered Extracellular Vesicles Derived from Dermal Fibroblasts Attenuate Inflammation in a Murine Model of Acute Lung Injury

Acute respiratory distress syndrome (ARDS) represents a significant burden to the healthcare system, with ≈200 000 cases diagnosed annually in the USA. ARDS patients suffer from severe refractory hypoxemia, alveolar-capillary barrier dysfunction, impaired surfactant function, and abnormal upregulation of inflammatory pathways that lead to intensive care unit admission, prolonged hospitalization, and increased disability-adjusted life years. Currently, there is no cure or FDA-approved therapy for ARDS. This work describes the implementation of engineered extracellular vesicle (eEV)-based nanocarriers for targeted nonviral delivery of anti-inflammatory payloads to the inflamed/injured lung. The results show the ability of surfactant protein A (SPA)-functionalized IL-4- and IL-10-loaded eEVs to promote intrapulmonary retention and reduce inflammation, both in vitro and in vivo. Significant attenuation is observed in tissue damage, proinflammatory cytokine secretion, macrophage activation, influx of protein-rich fluid, and neutrophil infiltration into the alveolar space as early as 6 h post-eEVs treatment. Additionally, metabolomics analyses show that eEV treatment causes significant changes in the metabolic profile of inflamed lungs, driving the secretion of key anti-inflammatory metabolites. Altogether, these results establish the potential of eEVs derived from dermal fibroblasts to reduce inflammation, tissue damage, and the prevalence/progression of injury during ARDS via nonviral delivery of anti-inflammatory genes/transcripts.

Irisin attenuates fine particulate matter induced acute lung injury by regulating Nod2/NF-κB signaling pathway

Air pollution consisting of fine particulate matter (PM2.5) can induce or aggravate pulmonary inflammatory injury. Irisin has been shown to inhibit inflammation and help to protect against acute kidney, lung or brain injury. However, the role of irisin in lung inflammation after exposure to PM2.5 remains unclear. The aim of this study was to investigate the effect and molecular mechanism of irisin supplementation on in vitro and in vivo models of PM2.5-induced acute lung injury（ALI). C57BL/6 mice and alveolar macrophage cell line (MH-S) were treated with PM2.5. Histopathological examination and FNDC5/ irisin immunofluorescence staining was performed on lung tissue sections. MH-S cell viability was determined by CCK-8 assay. The levels of Nod2, NF-κB p65 and NLRP3 were detected by qRT-PCR and western blotting. The levels of cytokines (IL-1β, IL-18 and TNF-α) were detected by ELISA. PM2.5 exposure induced increased secretion of pro-inflammatory factors and activation of Nod2, NF-κB p65 and NLRP3 as well as endogenous levels of irisin. In vivo and in vitro inflammation was alleviated by irisin supplementation. Irisin significantly decreased IL-1β, IL-18, and TNF-α production at both mRNA and protein level. Expression levels of Nod2, NF-κB p65, and NLRP3 were all significantly affected by irisin. In vivo the degree of pulmonary injury and inflammatory infiltration was weakened after irisin administration. In vitro, irisin could inhibit the activation of the NLRP3 inflammasome for a sustained period of 24 h, and its inhibitory ability was gradually enhanced. In conclusion, our findings indicate that irisin can modulate the inflammatory injury of lung tissue caused by PM2.5 through the Nod2/NF-κB signaling pathway, suggesting that irisin can be a candidate for the therapeutic or preventive intervention in acute lung inflammation.

Alarmins and MicroRNAs, a New Axis in the Genesis of Respiratory Diseases: Possible Therapeutic Implications

It is well ascertained that airway inflammation has a key role in the genesis of numerous respiratory pathologies, including asthma, chronic obstructive pulmonary disease, and acute respiratory distress syndrome. Pulmonary tissue inflammation and anti-inflammatory responses implicate an intricate relationship between local and infiltrating immune cells and structural pulmonary cells. Alarmins are endogenic proteins discharged after cell injury in the extracellular microenvironment. The purpose of our review is to highlight the alterations in respiratory diseases involving some alarmins, such as high mobility group box 1 (HMGB1) and interleukin (IL)-33, and their inter-relationships and relationships with genetic non-coding material, such as microRNAs. The role played by these alarmins in some pathophysiological processes confirms the existence of an axis composed of HMGB1 and IL-33. These alarmins have been implicated in ferroptosis, the onset of type 2 inflammation and airway alterations. Moreover, both factors can act on non-coding genetic material capable of modifying respiratory function. Finally, we present an outline of alarmins and RNA-based therapeutics that have been proposed to treat respiratory pathologies.

Design, synthesis, and bioactivity evaluation of novel 1-(4-(benzylsulfonyl)-2-nitrophenyl) derivatives as potential anti-inflammatory agents against LPS-induced acute lung injury

Acute lung injury (ALI) is a devastating disease with a high mortality rate of 30%-40%. There is an unmet clinical need owing to limited treatment strategies and little clinical benefit. The pathology of ALI indicates that reducing the inflammatory response could be a highly desirable strategy to treat ALI. In this study, we designed and synthesized 36 novel 1-(4-(benzylsulfonyl)-2-nitrophenyl) derivatives and evaluated their anti-inflammatory activities by measuring the release of cytokines in lipopolysaccharide (LPS)-challenged J774A.1 cells. Compounds 19, 20, and 39 potently reduced the release of IL-6 and TNF-α in J774A.1 cells. Additionally, 39 improved LPS-induced ALI in vivo and inhibited cytokine production in lung tissues. Furthermore, 39 reduced inflammatory infiltration and downregulated p-p65 levels in lung tissues. Thus, compound 39 could serve as a new lead structure for the development of anti-inflammatory drugs to treat ALI.

Cryptotanshinone attenuates LPS-induced acute lung injury by regulating metabolic reprogramming of macrophage

Background

Acute lung injury (ALI) is a life-threatening inflammatory disease without effective therapeutic regimen. Macrophage polarization plays a key role in the initiation and resolution of pulmonary inflammation. Therefore, modulating macrophage phenotype is a potentially effective way for acute lung injury. Cryptotanshinone (CTS) is a lipophilic bioactive compound extracted from the root of Salvia miltiorrhiza with a variety of pharmacological effects, especially the anti-inflammatory role. In this study, we investigated the therapeutic and immunomodulatory effects of CTS on ALI.

Materials and methods

The rat model of ALI was established by intratracheal instillation of LPS (5 mg/kg) to evaluate the lung protective effect of CTS in vivo and to explore the regulation of CTS on the phenotype of lung macrophage polarization. LPS (1 μg/mL) was used to stimulate RAW264.7 macrophages in vitro to further explore the effect of CTS on the polarization and metabolic reprogramming of RAW264.7 macrophages and to clarify the potential mechanism of CTS anti-ALI.

Results

CTS significantly improved lung function, reduced pulmonary edema, effectively inhibited pulmonary inflammatory infiltration, and alleviated ALI. Both in vivo and in vitro results revealed that CTS inhibited the differentiation of macrophage into the M1 phenotype and promoted polarization into M2 phenotype during ALI. Further in vitro studies indicated that CTS significantly suppressed LPS-induced metabolic transition from aerobic oxidation to glycolysis in macrophages. Mechanistically, CTS blocked LPS-induced metabolic transformation of macrophages by activating AMPK.

Conclusion

These findings demonstrated that CTS regulates macrophage metabolism by activating AMPK, and then induced M1-type macrophages to transform into M2-type macrophages, thereby alleviating the inflammatory response of ALI, suggesting that CTS might be a potential anti-ALI agent.

Knockdown of SHP2 attenuated LPS-induced ferroptosis via downregulating ACSL4 expression in acute lung injury

BACKGROUND

Acute lung injury (ALI) is a complex disease with a high mortality. Src homology 2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2) is a protein tyrosine phosphatase that participates in pathogenesis of multiple diseases. Nevertheless, the role of SHP2 in ALI remains unknown.

METHODS

The in vivo and in vitro lipopolysaccharide (LPS)-induced ALI models were successfully established. The histopathological changes were evaluated by hematoxylin and eosin staining. The vascular permeability of lungs was assessed by Evans blue assay. The expression of ACSL4 and SHP2 was detected by western blot and qRT-PCR assay. The lactate dehydrogenase (LDH) activity, malondialdehyde (MDA), iron, and glutathione (GSH) levels were measured by commercial kits.

RESULTS

The SHP2 was upregulated in LPS-induced ALI mice and LPS-stimulated MLE-12 cells. In loss-of function experiment, the knockdown of SHP2 attenuated LPS-induced lung injury, microvessels damage, pulmonary edema, and increase of lung vascular permeability in vivo. Mechanically, shSHP2-rescued LPS induced increase in LDH activity, MDA, and iron levels, and decrease in GSH levels, as well as the accumulation of reactive oxygen species in vivo and in vitro, leading to an alleviation of LPS-induced ferroptosis. Notably, shSHP2 reduced the expression of Acyl-CoA synthetase long-chain 4 (ACSL4). In the rescued experiments, overexpression of ACSL4 abolished the shSHP2-induced reduction of LDH activity, MDA, and iron levels, and increase in GSH levels, thereby aggravating the LPS-induced ferroptosis.

CONCLUSION

These findings concluded that the knockdown of SHP2 attenuated LPS-induced ferroptosis via downregulation of ACSL4 expression in ALI, providing a novel sight for ALI treatment.

Small extracellular vesicles derived from Nrf2-overexpressing human amniotic mesenchymal stem cells protect against lipopolysaccharide-induced acute lung injury by inhibiting NLRP3

BACKGROUND

Acute lung injury (ALI) is a major cause of respiratory failure in critically ill patients that results in significant morbidity and mortality. Recent studies indicate that cell-based therapies may be beneficial in the treatment of ALI. We recently demonstrated that Nrf2-overexpressing human amniotic mesenchymal stem cells (hAMSCs) reduce lung injury, fibrosis and inflammation in lipopolysaccharide (LPS)-challenged mice. Here we tested whether small extracellular vesicles (sEVs) derived from Nrf2-overexpressing hAMSCs (Nrf2-sEVs) could protect against ALI. sEVs were isolated from hAMSCs that overexpressed (Nrf2-sEVs) or silenced (siNrf2-sEVs) Nrf2. We examined the effects of sEVs treatment on lung inflammation in a mouse model of ALI, where LPS was administered intratracheally to mice, and lung tissues and bronchoalveolar lavage fluid (BALF) were analyzed 24 h later.

METHODS

Histological analysis, immunofluorescence microscopy, western blotting, RT-PCR and ELISA were used to measure the inflammatory response in the lungs and BALF.

RESULTS

We found that sEVs from hAMSCs are protective in ALI and that Nrf2 overexpression promotes protection against lung disease. Nrf2-sEVs significantly reduced lung injury in LPS-challenged mice, which was associated with decreased apoptosis, reduced infiltration of neutrophils and macrophages, and inhibition of pro-inflammatory cytokine expression. We further show that Nrf2-sEVs act by inhibiting the activation of the NLRP3 inflammasome and promoting the polarization of M2 macrophages.

CONCLUSION

Our data show that overexpression of Nrf2 protects against LPS-induced lung injury, and indicate that a novel therapeutic strategy using Nrf2-sEVs may be beneficial against ALI.

Extracellular vesicles in the pathogenesis and treatment of acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are common life-threatening lung diseases associated with acute and severe inflammation. Both have high mortality rates, and despite decades of research on clinical ALI/ARDS, there are no effective therapeutic strategies. Disruption of alveolar-capillary barrier integrity or activation of inflammatory responses leads to lung inflammation and injury. Recently, studies on the role of extracellular vesicles (EVs) in regulating normal and pathophysiologic cell activities, including inflammation and injury responses, have attracted attention. Injured and dysfunctional cells often secrete EVs into serum or bronchoalveolar lavage fluid with altered cargoes, which can be used to diagnose and predict the development of ALI/ARDS. EVs secreted by mesenchymal stem cells can also attenuate inflammatory reactions associated with cell dysfunction and injury to preserve or restore cell function, and thereby promote cell proliferation and tissue regeneration. This review focuses on the roles of EVs in the pathogenesis of pulmonary inflammation, particularly ALI/ARDS.

Analysis of the Relevant Vital Signs and Infection of Sepsis Patients and to Explore the Influencing Factors of Acute Lung Injury/Acute Respiratory Distress Syndrome

In order to analyze the relevant vital signs and infection of sepsis patients, the influencing factors of acute lung injury/acute respiratory distress syndrome (ALI/ARDS) are explored. A total of 142 sepsis patients admitted to our hospital from January 2019 to January 2022 are divided into an ALI/ARDS group and a non-ALI/ARDS group according to the incidence of ALI/ARDS. Logistic analysis showed that pulmonary/abdominal infection, fungal origin of infection, Acinetobacter baumannii, low oxygenation index, high blood lactic acid value, APACHE II score, SOFA score, and LIPS score are the risk factors for sepsis-induced ALI/ARDS. The results indicate that pulmonary/abdominal infection, fungal origin of infection, Acinetobacter baumannii, low oxygenation index, high blood lactic acid, APACHE II score, SOFA score, and LIPS score are the risk factors for sepsis induced ALI/ARDS.

Advances in the use of exosomes for the treatment of ALI/ARDS

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a critical clinical syndrome with high morbidity and mortality. Currently, the primary treatment for ALI/ARDS is mainly symptomatic therapy such as mechanical ventilation and fluid management. Due to the lack of effective treatment strategies, most ALI/ARDS patients face a poor prognosis. The discovery of exosomes has created a promising prospect for the treatment of ALI/ARDS. Exosomes can exert anti-inflammatory effects, inhibit apoptosis, and promote cell regeneration. The microRNA contained in exosomes can participate in intercellular communication and play an immunomodulatory role in ALI/ARDS disease models. This review discusses the possible mechanisms of exosomes in ALI/ARDS to facilitate the development of innovative treatments for ALI/ARDS.

Cell-free therapy based on stem cell-derived exosomes: A promising approach for wound healing

There are several successive and overlapping phases in wound healing as a complex process. By the disruption of each of thesephases, chronic non-healing wounds are resultant. Despite the present soothing surgeries, standard wound dressings, and topical gels, the wound is often not completelyclosed. Today, stem cells have attracted a huge deal of attention therapeutically and pharmaceutically considering their unique features. However, they have some restrictions. Moreover, it is hoped to eliminate the limitations of cellular therapies based on their derivatives known as exosomes. Exosomes are extracellular vesicles secreted from cells. They have a diameter of almost 30-150 nm and miRNAs, mRNAs, and proteins that are possibly different from the source cell are included in exosomal contents. Such nanovesicles have a key role in the intercellular communication of pathological and physiological procedures. Exosome-based therapy is a new significant method for wound healing. By exosomes effects, wound management may be improved and a new therapeutic model may be highlighted for cell-free therapies with reduced side effects for the wound repair. This article is protected by copyright. All rights reserved.

Mesenchymal Stem Cells Attenuate Acute Lung Injury in Mice Partly by Suppressing Alveolar Macrophage Activation in a PGE2-Dependent Manner

Mesenchymal stem cells (MSCs) have been demonstrated to attenuate acute lung injury (ALI). We also found that they can suppress the activation of alveolar macrophages (AMs), which can partly account for their therapeutic effects. MSCs do not inherently own immunosuppressive effects, when co-cultured with inflammatory immune cells, MSCs can be activated by inflammatory cytokines and meanwhile exert immunosuppressive effects. In order to further research, RNA sequencing (RNA-seq) of MSCs cultured before and after co-culturing with activated macrophages was performed. The data suggested a total of 5268 differentially expressed genes (DEGs) along the process. We used the data of 2754 upregulated DEGs to develop a signaling network of genes and the transcription factors targeting them in order to predict the altered functions of MSCs after exposure to inflammatory stimuli. This constructed network revealed some critical target genes and potential roles of MSCs under inflammatory conditions. According to the network, Ptgs2 was assumed to be an important gene participating in the immunosuppressive effects of MSCs. We also identified significant increases in the expression of COX2 protein and the secretion of PGE2 from MSCs. The use of the COX2 inhibitor NS-398 restrained the secretion of PGE2 and reversed the suppression of macrophage activation by MSCs in vitro. In addition, a selective antagonist of PGE2 binding receptor (EP4 receptor), GW627368X, also reversed the inhibitory effects of MSCs on AMs and the protective effects in ALI mouse. In summary, the therapeutic effects of MSCs on ALI partly occur through suppressing AM activation via PGE2 binding to EP4 receptor.

Alveolar macrophage-derived exosomal tRF-22-8BWS7K092 activates Hippo signaling pathway to induce ferroptosis in acute lung injury

BACKGROUND

Alveolar macrophages (AMs) play a demonstrative role in acute lung injury (ALI). Exosomes act as signaling molecules to regulate cell-to-cell communication by releasing RNAs. Transfer RNA-derived fragments (tRFs) possess potential functions in multiple diseases through ferroptosis. The present study aims to reveal the role of AM-derived exosomal tRFs in ALI and to identify the relationship to ferroptosis.

METHODS

ALI mice model was established by lipopolysaccharide (LPS) induction. RNA sequencing was performed to identify the tRFs profile in bronchoalveolar lavage fluid (BALF) exosomes of ALI mice. After interfering with the expression of candidate tRFs in AMs or alveolar epithelial cells (MLE-12), the effect of oxidative stress and expression of ferroptosis-related proteins were detected.

RESULTS

Exosomes isolated from BALF of ALI mice were dominated by a macrophage immunophenotype. RNA-sequencing identified 4 up- and 10 down-regulated differentially expressed tRFs (DEtRFs), among which tRF-22-8BWS7K092 expression was significantly increased in LPS-induced macrophage-derived exosomes (LPS-exo). Hippo signaling pathway was the most significantly enriched KEGG pathways for DEtRFs. LPS-exo inhibited cell viability and the expression of GPX4 and FTH1, and enhanced oxidative stress in MLE-12 cells. Ferroptosis inhibitor reversed the inhibition of LPS-exo on cell viability and tRF-22-8BWS7K092 inhibitor rescued above effect of LPS-exo on MLE-12 cells. Besides, tRF-22-8BWS7K092 could activate Hippo signaling pathway by binding Wnt5B, inducing ferroptosis in MLE-12 cells.

CONCLUSION

BALF exosomes of ALI mice were mainly derived from AMs. AM-derived exosomal tRF-22-8BWS7K092 activates the Hippo signaling pathway to induce ferroptosis, thus contributing to the pathogenesis of ALI.

The role of exosomal miRNA in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) impacts more than one-third of the population and is linked with other metabolic diseases. The term encompasses a wide spectrum of diseases, from modest steatosis to nonalcoholic steatohepatitis, fibrosis and, ultimately, cirrhosis with the potential for development of hepatocellular carcinoma. Currently, available methods for diagnosing NAFLD are invasive or lack accuracy, and monitoring to determine response to therapeutic interventions is challenging. Exosomes are nano-scaled extracellular vesicles that are secreted by a variety of cells. They convey proteins, mRNA, miRNA, and other bioactive molecules between cells and are involved in an extensive range of biological processes, particularly cell-cell communication. Several reports suggest that exosomes mediate miRNAs and, thus, they have potential clinical utility for diagnosis, prognosis, and therapeutics in liver diseases. In view of the vital role of exosomal microRNA in disease, we here synthesized current knowledge about the biogenesis of exosomal miRNA and exosome-mediated microRNA transfer. We then discuss the potential of exosomal miRNA in diagnosis and therapeutics of NAFLD.

Pulmonary delivery of siRNA against acute lung injury/acute respiratory distress syndrome

The use of small interfering RNAs (siRNAs) has been under investigation for the treatment of several unmet medical needs, including acute lung injury/acute respiratory distress syndrome (ALI/ARDS) wherein siRNA may be implemented to modify the expression of pro-inflammatory cytokines and chemokines at the mRNA level. The properties such as clear anatomy, accessibility, and relatively low enzyme activity make the lung a good target for local siRNA therapy. However, the translation of siRNA is restricted by the inefficient delivery of siRNA therapeutics to the target cells due to the properties of naked siRNA. Thus, this review will focus on the various delivery systems that can be used and the different barriers that need to be surmounted for the development of stable inhalable siRNA formulations for human use before siRNA therapeutics for ALI/ARDS become available in the clinic.

MicroRNA-16 regulates lipopolysaccharide-induced inflammatory factor expression by targeting TLR4 in normal human bronchial epithelial cells

Acute lung injury (ALI) is mainly caused by inflammation and is associated with high mortality rates. Emerging evidence has suggested that microRNAs (miRNAs or miRs) serve a significant function in ALI. However, the fundamental mechanism underlying ALI remain to be fully elucidated. Although miR-16 has been reported to be involved in the occurrence and development of a number of diseases its association with ALI has not been previously investigated. Therefore, the present study aimed to explore the role of miR-16 in the lipopolysaccharide (LPS)-induced ALI model. The expression levels of tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6 were measured by ELISA in the blood samples of rats with ALI and in the normal human bronchial epithelial (NHBE) cell line. The role of miR-16 in inflammation was evaluated using gene overexpression and silencing experiments in NHBE cells by reverse transcription-quantitative PCR. In addition, the expression levels of inflammatory factors TNF-α, IL-1β and IL-6 were also determined using ELISA. The potential interaction between miR-16 and TLR4 was assessed using bioinformatics analysis by the TargetScan database and then verified in 293T cells using luciferase reporter assay. The expression of miR-16 was notably decreased in the lung tissues of rats with LPS-induced ALI compared with the PBS treated-group. Additionally, the levels of the proinflammatory cytokines TNF-α, IL-1β and IL-6 were reduced following transfection of NHBE cells with miR-16 mimics compared with those in the miR-negative control group. Western blot analysis revealed that miR-16 overexpression could downregulate TLR4 expression in NHBE cells compared with that in the miR-NC group. Luciferase reporter assay confirmed that TLR4 may be directly targeted by miR-16. The effect of miR-16 on TLR4 was rescued in NHBE cells following treatment with LPS. Overall, these aforementioned findings suggest that miR-16 may serve a protective role against LPS-mediated inflammatory responses in NHBE cells by regulating TLR4, where this mechanism may be considered to be a novel approach for treating ALI in the future.

Combined topical and systemic administration with human adipose-derived mesenchymal stem cells (hADSC) and hADSC-derived exosomes markedly promoted cutaneous wound healing and regeneration

Background

Cutaneous wound healing and regeneration have become a recognized health challenge in the world, which causes severe damage to the mental and physical health of patients. Human adipose-derived mesenchymal stem cells (hADSC) play an essential role in wound healing via their paracrine function. Exosomes secreted by hADSC may contribute to this progress. In this study, we investigated the potential clinical application roles of hADSC and hADSC-derived exosomes (hADSC-Exo) in cutaneous wound healing.

Methods

hADSC-Exo was isolated from human hADSC by ultracentrifugation. Mice were subjected to a full-thickness skin biopsy experiment and treated with either control vehicle or hADSC or hADSC-Exo by smearing administration (sm) or subcutaneous administration (sc) or intravenous administration (iv). The efficacy of hADSC and hADSC-Exo on wound healing was evaluated by measuring wound closure rates, histological analysis.

Results

Combined application of local hADSC-Exo smearing and hADSC/hADSC-Exo intravenous administration offered the additional benefit of promoting wound healing, accelerating re-epithelialization, reducing scar widths, and enhancing angiogenesis and collagen synthesis. Either topical application of hADSC-Exo or systemic administration with hADSC/hADSC-Exo appeared more effective in stimulating cell proliferation, inhibiting cell apoptosis and inflammation, and promoting skin elasticity and barrier integrity, with increased genes expression of PCNA, VEGF, collagen III, Filaggrin, Loricrin, and AQP3, with decreased genes expression of TNF-alpha.

Conclusion

Our findings suggest that the combined administration of hADSC/hADSC-Exo can facilitate cutaneous wound healing and reduce scar formation. These data provide the first evidence for the feasibility of smearing of hADSC-Exo as a cell-free therapy in treating cutaneous wounds, and the potential clinical value of combined administration of hADSC/hADSC-Exo.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02287-9.