Alveolar Capillary Endothelial Cells Research Articles

Peptide-functionalized chitosan-based microcapsules for dual active targeted treatment of lung infections

Lung infections, such as: pneumonia, chronic obstructive cystic fibrosis, tuberculosis are generally caused by viruses, bacteria and fungi. As these infections are very difficult to treat, new therapeutic approaches are investigated in order to maximize the efficiency of the treatment and to reduce the major complications that can occur. The main objective of this study was focused on the preparation of drug-loaded peptides-functionalized microcapsules, obtained by a double emulsion, based on carboxylated chitosan (CMCS), poly(vinyl alcohol) (PVA) and an activator [4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride] (DMT-MM), for the dual active targeting and treatment of pulmonary infections. The microcapsules were functionalized on the surface with both CGSPGWVRC and indolicidin (IN) peptides, as effective ligands for the active targeting of both alveolar capillary endothelial cells and bacterial cells. FTIR spectroscopy confirmed the formation of ester and amide bonds into the structure of prepared microcapsules. Microcapsules diameter varied between 893 and 965 nm. The swelling degree in PBS, at pH 7.4, ranged between 1760 %- 2100 %. All the analyzed samples showed hemolysis degrees lower than 2 %, which demonstrated their non-hemolytic character. Evaluation of the impact of microcapsules on WI-38 normal human lung cells and RAW 264.7 mouse macrophages revealed a non-toxic or slightly cytotoxic effect. Internalization assay proved that microcapsules were localized at intracellular level.

Mast cell degranulation-triggered by SARS-CoV-2 induces tracheal-bronchial epithelial inflammation and injury

SARS-CoV-2 infection-induced hyper-inflammation is a key pathogenic factor of COVID-19. Our research, along with others', has demonstrated that mast cells (MCs) play a vital role in the initiation of hyper-inflammation caused by SARS-CoV-2. In previous study, we observed that SARS-CoV-2 infection induced the accumulation of MCs in the peri-bronchus and bronchioalveolar-duct junction in humanized mice. Additionally, we found that MC degranulation triggered by the spike protein resulted in inflammation in alveolar epithelial cells and capillary endothelial cells, leading to subsequent lung injury. The trachea and bronchus are the routes for SARS-CoV-2 transmission after virus inhalation, and inflammation in these regions could promote viral spread. MCs are widely distributed throughout the respiratory tract. Thus, in this study, we investigated the role of MCs and their degranulation in the development of inflammation in tracheal-bronchial epithelium. Histological analyses showed the accumulation and degranulation of MCs in the peri-trachea of humanized mice infected with SARS-CoV-2. MC degranulation caused lesions in trachea, and the formation of papillary hyperplasia was observed. Through transcriptome analysis in bronchial epithelial cells, we found that MC degranulation significantly altered multiple cellular signaling, particularly, leading to upregulated immune responses and inflammation. The administration of ebastine or loratadine effectively suppressed the induction of inflammatory factors in bronchial epithelial cells and alleviated tracheal injury in mice. Taken together, our findings confirm the essential role of MC degranulation in SARS-CoV-2-induced hyper-inflammation and the subsequent tissue lesions. Furthermore, our results support the use of ebastine or loratadine to inhibit SARS-CoV-2-triggered degranulation, thereby preventing tissue damage caused by hyper-inflammation.

Acute respiratory distress syndrome heterogeneity and the septic ARDS subgroup.

Acute respiratory distress syndrome (ARDS) is an acute diffuse inflammatory lung injury characterized by the damage of alveolar epithelial cells and pulmonary capillary endothelial cells. It is mainly manifested by non-cardiogenic pulmonary edema, resulting from intrapulmonary and extrapulmonary risk factors. ARDS is often accompanied by immune system disturbance, both locally in the lungs and systemically. As a common heterogeneous disease in critical care medicine, researchers are often faced with the failure of clinical trials. Latent class analysis had been used to compensate for poor outcomes and found that targeted treatment after subgrouping contribute to ARDS therapy. The subphenotype of ARDS caused by sepsis has garnered attention due to its refractory nature and detrimental consequences. Sepsis stands as the most predominant extrapulmonary cause of ARDS, accounting for approximately 32% of ARDS cases. Studies indicate that sepsis-induced ARDS tends to be more severe than ARDS caused by other factors, leading to poorer prognosis and higher mortality rate. This comprehensive review delves into the immunological mechanisms of sepsis-ARDS, the heterogeneity of ARDS and existing research on targeted treatments, aiming to providing mechanism understanding and exploring ideas for accurate treatment of ARDS or sepsis-ARDS.

Abstract 16783: Discovery and Characterization of Transient Endothelial Stem-Like Cells Responsible for Rapid Lung Microvascular Regeneration Post Endothelial Ablation

Background: Single-cell RNA sequencing (scRNA-seq) has revealed two main types of alveolar capillary endothelial cells (ECs): aCap ECs (or aerocytes) express typical aCap markers, including apelin, whereas general (gCap) ECs express apelin receptor, Aplnr /APJ. Aerocytes constitute the air-blood barrier and are incapable of proliferation, unlike smaller gCap ECs that can proliferate. Hypothesis: After lung microvascular injury, gCap ECs give rise to stem-like ECs that can regenerate depleted lung EC populations, including highly specialized aerocytes. Approach: scRNA-seq was used to study depletion and regeneration of lung EC populations after intratracheal instillation of diphtheria toxin (DT) in transgenic mice harboring an EC-targeted human DT receptor. Results: DT resulted in ~80% loss of lung microvascular EC populations including aerocytes, associated with severe acute lung injury (ALI), and there was full spontaneous recovery by day 7. Interestingly, a novel EC population appeared at day 3 post injury in a transitional gCap EC cluster characterized by paradoxical expression of ‘aCap’ marker, apelin, together with endothelial progenitor/stem cell markers, Cd34 and endothelial protein C receptor ( Procr /EPCR). These ‘transient endothelial stem-like cells’ (TESCs) transitioned to highly proliferative progenitor-like FoxM1 + cells ultimately repopulating all depleted EC populations by day 7. Using flow cytometry of lung cells harvested at 3 days post DT instillation, TESCs were identified by unique co-expression of CD34 and EPCR (Figure), thereby allowing isolation and culture in vitro for further characterization of their proliferation and differentiation potential. Conclusions: Lung microvascular repair is orchestrated by the emergence of stem-like, gCap ECs (TESCs), transiently expressing aCap/aerocyte marker, apelin, together with Procr /EPCR, which have the capacity to regenerate lung microvasculature rapidly and efficiently.

Effects of the PI3K/Akt/HO-1 pathway on autophagy in a sepsis-induced acute lung injury mouse model

Sepsis-induced lung injury is an acute hypoxic respiratory insufficiency caused by systemic infectious factors that results in alveolar epithelial cell and capillary endothelial cell injury, diffuse pulmonary interstitial edema, and alveolar edema. Heme oxygenase (HO)-1 is usually associated with inflammation and has anti-inflammatory effects. Autophagy is a degradation pathway that eliminates cellular metabolic waste and plays an important protective role during stress. The phosphatidylinositol 3-kinase/ protein kinase B (PI3K/Akt) signaling pathway plays a key role in mediating cellular responses to inflammatory reactions. Therefore, we hypothesized that HO-1 is associated with autophagy and regulated by the PI3K/Akt signaling pathway in mice with sepsis-induced lung injury. Sepsis-induced lung injury was induced in mice using cecal ligation and puncture (CLP). Hemin or Sn-protoporphyrin IX (SnPP) was administered via intraperitoneal injection before surgery. Survival rates were observed during days 1–7 after the surgery; lung histology was discerned 24 h after the surgery; pro-inflammatory and anti-inflammatory factors in plasma and lung tissue were measured using enzyme-linked immunosorbent assay (ELISA); HO-1, Beclin-1, microtubule-associated protein 1 light chain 3B (LC3B)-II, p62 and lysosome associated membrane protein (LAMP)2 protein expression levels were measured 24 h after the surgery; HO-1 and LC3B-II protein expression levels were observed using immunofluorescence 24 h after the surgery; and autophagosomes were detected using electron microscopy 24 h after the surgery. Furthermore, when PI3K inhibitors LY294002, PI3K activators Recilisib and hemin were administered before the surgery, Akt, p-Akt, HO-1, and LC3-II levels were measured 24 h post-surgery. We found that HO-1 overexpression increased the survival rate and inhibited sepsis-induced lung injury. HO-1 overexpression attenuated the levels of proinflammatory cytokines (TNF-α, IL-1β) and increased the anti-inflammatory cytokine (IL-10, HO-1) overexpression. Moreover, HO-1 overexpression was also associated with increased expression of Beclin-1, LC3B-II and LAMP2 protein expression; decreased p62 protein expression; and significantly increased autophagosome formation. The results for HO-1-downregulated mice contrasted with those mentioned above. LY294002 inhibited p-Akt/Akt, HO-1, and LC3B-II protein expression; and hemin reversed the inhibitory effect of LY294002. The protective effect of HO-1 was involved in the mediation of autophagy, which may be regulated by the PI3K/Akt signaling pathway during sepsis-induced lung injury in mice.

CCRL2 Expression by Specialized Lung Capillary Endothelial Cells Controls NK-cell Homing in Lung Cancer.

Patterns of receptors for chemotactic factors regulate the homing of leukocytes to tissues. Here we report that the CCRL2/chemerin/CMKLR1 axis represents a selective pathway for the homing of natural killer (NK) cells to the lung. C-C motif chemokine receptor-like 2 (CCRL2) is a nonsignaling seven-transmembrane domain receptor able to control lung tumor growth. CCRL2 constitutive or conditional endothelial cell targeted ablation, or deletion of its ligand chemerin, were found to promote tumor progression in a Kras/p53Flox lung cancer cell model. This phenotype was dependent on the reduced recruitment of CD27- CD11b+ mature NK cells. Other chemotactic receptors identified in lung-infiltrating NK cells by single-cell RNA sequencing (scRNA-seq), such as Cxcr3, Cx3cr1, and S1pr5, were found to be dispensable in the regulation of NK-cell infiltration of the lung and lung tumor growth. scRNA-seq identified CCRL2 as the hallmark of general alveolar lung capillary endothelial cells. CCRL2 expression was epigenetically regulated in lung endothelium and it was upregulated by the demethylating agent 5-aza-2'-deoxycytidine (5-Aza). In vivo administration of low doses of 5-Aza induced CCRL2 upregulation, increased recruitment of NK cells, and reduced lung tumor growth. These results identify CCRL2 as an NK-cell lung homing molecule that has the potential to be exploited to promote NK cell-mediated lung immune surveillance.

Long non-coding RNA PFI inhibits apoptosis of alveolar epithelial cells to alleviate lung injury via miR-328-3p/Creb1 axis

Acute lung injury (ALI), a common clinical type of critical illness, is an acute hypoxic respiratory insufficiency caused by the damage of alveolar epithelial cells and capillary endothelial cells. In a previous study, we reported a novel lncRNA, lncRNA PFI, which could protect against pulmonary fibrosis in pulmonary fibroblasts. The present study demonstrated that lncRNA PFI was downregulated in alveolar epithelial cell of mice injury lung tissues, and further investigated the role of lncRNA PFI in regulating inflammation-induced alveolar epithelial cell apoptosis. Overexpression of lncRNA PFI could partially abrogated bleomycin induced type II AECs injured. Subsequently, bioinformatic prediction revealed that lncRNA PFI might directly bind to miR-328-3p, and further AGO-2 RNA binding protein immunoprecipitation (RIP) assay confirmed their binding relationship. Furthermore, miR-328-3p promoted apoptosis in MLE-12 cells by limiting the activation of the Creb1, a protein correlated with cell apoptosis, whereas AMO-328-3p ablated the pro-apoptosis effect of silencing lncRNA PFI in MLE-12 cells. While miR-328-3p could also ablate the function of lncRNA PFI in bleomycin treated human lung epithelial cells. Enhanced expression of lncRNA PFI reversed the LPS-induced lung injury in mice. Overall, these data reveal that lncRNA PFI mitigated acute lung injury through miR-328-3p/Creb1 pathway in alveolar epithelial cells.

Overexpression of FoxM1 optimizes the therapeutic effect of bone marrow mesenchymal stem cells on acute respiratory distress syndrome

BackgroundInjury of alveolar epithelial cells and capillary endothelial cells is crucial in the pathogenesis of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). Mesenchymal stem cells (MSCs) are a promising cell source for ALI/ARDS treatment. Overexpression of Fork head box protein M1 (FoxM1) facilitates MSC differentiation into alveolar type II (AT II) cells in vitro. Moreover, FoxM1 has been shown to repair the endothelial barrier. Therefore, this study explored whether overexpression of FoxM1 promotes the therapeutic effect of bone marrow-derived MSCs (BMSCs) on ARDS by differentiation of BMSCs into AT II cells or a paracrine mechanism.MethodsA septic ALI model was established in mice by intraperitoneal administration of lipopolysaccharide. The protective effect of BMSCs-FoxM1 on ALI was explored by detecting pathological variations in the lung, total protein concentration in bronchoalveolar lavage fluid (BALF), wet/dry (W/D) lung weight ratio, oxidative stress levels, cytokine levels, and retention of BMSCs in the lung. In addition, we assessed whether FoxM1 overexpression promoted the therapeutic effect of BMSCs on ALI/ARDS by differentiating into AT II cells using SPC−/− mice. Furthermore, the protective effect of BMSCs-FoxM1 on lipopolysaccharide-induced endothelial cell (EC) injury was explored by detecting EC proliferation, apoptosis, scratch wounds, tube formation, permeability, and oxidative stress, and analyzing whether the Wnt/β-catenin pathway contributes to the regulatory mechanism in vitro using a pathway inhibitor.ResultsCompared with BMSCs-Vector, treatment with BMSCs-FoxM1 significantly decreased the W/D lung weight ratio, total BALF protein level, lung injury score, oxidative stress, and cytokine levels. With the detected track of BMSCs-FoxM1, we observed a low residency rate and short duration of residency in the lung. Notably, SPC was not expressed in SPC−/− mice injected with BMSCs-FoxM1. Furthermore, BMSCs-FoxM1 enhanced EC proliferation, migration, and tube formation; inhibited EC apoptosis and inflammation; and maintained vascular integrity through activation of the Wnt/β-catenin pathway, which was partially reversed by XAV-939.ConclusionOverexpression of FoxM1 enhanced the therapeutic effect of BMSCs on ARDS, possibly through a paracrine mechanism rather than by promoting BMSC differentiation into AT II cells in vivo, and prevented LPS-induced EC barrier disruption partially through activating the Wnt/β-catenin signaling pathway in vitro.

Uridine alleviates LPS-induced ARDS and improves insulin sensitivity by decreasing oxidative stress and inflammatory processes.

Acute respiratory distress syndrome (ARDS) refers to the injury of alveolar epithelial cells and capillary endothelial cells due to various injury factors. Research on the pathogenesis of ARDS has made great progress, but the exact pathogenesis of ARDS has not been fully elucidated. Up to now, the prevention and treatment of ARDS is still an important scientific problem that needs to be solved urgently. In this work, we analyzed the effect of uridine on ARDS. An ARDS model was successfully constructed by lipopolysaccharide (LPS) stimulation. Western-blotting, IFA, ELISA, RT-PCT and CLSM were conducted to investigate the effect of uridine on ARDS and insulin resistance, and the results showed that lung histopathological alterations were significantly attenuated by uridine treatment. Further work showed that the levels of proinflammatory cytokines were significantly down-regulated in the lung tissue after treatment with uridine. Additionally, the numbers of total cells and neutrophils in the bronchoalveolar lavage fluid (BALF) were also decreased in the uridine-treated ARDS mice. We further explored the potential mechanism by which uridine could treat ARDS, and the results indicated that NF-κB signaling was down-regulated by uridine treatment. Next, we studied insulin sensitivity in the ARDS mice, and found that insulin signaling was significantly down-regulated, and uridine could enhance insulin sensitivity in the ARDS mice model. Furthermore, we found that the levels of inflammation and oxidative stress were decreased by uridine treatment, which may be the potential mechanism by which uridine could improve insulin sensitivity. Taken together, the current work provides evidence that uridine can serve as a potential drug to treat ARDS and insulin resistance.

Single‐Cell Sequencing in the Genetic Model of Mitochondrial Dysfunction Reveals Heterogeneity of Lung Endothelial Cells and Novel Targets in Pulmonary Hypertension

IntroductionPulmonary hypertension (PH) is a complex, lethal vascular disease and currently has very limited treatment options with no cure. Severe pulmonary vascular remodeling and right ventricular (RV) hypertrophy in PH ultimately lead to RV failure. Endothelial dysfunction (ED) is demonstrated to play a key role in the initiation of PH. However, the pathogenic mechanisms leading up to ED remain unclear.HypothesisWe hypothesized that mitochondrial dysfunction (MD) in endothelial cells (EC) would produce a specific gene expression pattern in each EC subpopulation, revealing pathogenic pathways that trigger ED.MethodsRats with the NFU1G206C mutation spontaneously develop PH, recapitulating the human disease in patients with multiple mitochondrial dysfunctions syndrome and PH. Transcriptomics was performed with the 10X Genomics kit on isolated single cell EC’s from WT and NFU1G206C rats. EC clustering was done with the Seurat V4 R package. The Database for Annotation, Visualization and Integrated Discovery (DAVID) identified enriched biological pathways. RV function was determined by echocardiography imaging (Vevo 3100 system).ResultsEcho results confirmed that NFU1G206C rats showed a spontaneous PH phenotype. Thirteen distinctive subpopulations of EC’s were identified in WT and NFU1G206C rats with UMAP and tSNE analysis, based on specific marker expressions such as alveolar capillary ECs (expressing ca4), small capillary ECs (fabp4), lymphatic ECs (prox1) and ECs regulating arteriogenesis (gja5) to ECs undergoing endothelial mesenchymal transition (EndMT) (acta2, encoding for α‐SMA). DAVID analysis of genes expressed in individual EC clusters showed heterogenous functions such as cell adhesion, inflammatory response, migration, and angiogenesis, highlighting the physiological relevance of EC’s. Cells were then classified as either senescent, quiescent, or proliferative, based on genes enriched in the respective pathways. We found that EC clusters of NFU1G206C rats significantly deviated from conventional gene expression profiles of WT clusters. The cluster1 of NFU1G206C rats showed an increase in senescence marker, lamb1 and decreased mki67. On the other hand, genes associated with proliferation were significantly increased in cluster2. We also identified EC’s with increased association of EndMT genes in cluster7. Most remarkably, in clusters 3, 5 and 9 of the NFU1G206C rats, we discovered a significant decrease in genes controlling cell adhesion and junction proteins, which could potentiate EC barrier dysfunction, an important contributor to PH pathobiology. These global aberrations from conventional EC functions could initiate pathobiological transformation.ConclusionWe demonstrate that EC functions are diverse and crucial for normal vascular function and maintenance. We also highlight that MD can shift the EC’s from their native to pathological states. Therefore, treatment approaches that attenuate MD or targets the specific changes leading up to ED would effectively control PH.

Correlation between circulating endothelial cell level and acute respiratory distress syndrome in postoperative patients.

BACKGROUNDAcute respiratory distress syndrome (ARDS) is injury of alveolar epithelial cells and capillary endothelial cells caused by various factors, including endogenous and exogenous lung factors, leading to diffuse pulmonary interstitial and alveolar edema, and acute respiratory failure. ARDS involves alveolar epithelial cells and pulmonary interstitial capillary endothelial cells. Circulating endothelial cells (CECs) are the only marker that directly reflects vascular endothelial injury in vivo. There have been few studies on the correlation between peripheral blood CECs and ARDS at home and abroad. The lungs are the organs with the highest capillary density and the most endothelial cells, thus, it is speculated that when ARDS occurs, CECs are stimulated and damaged, and released into the circulatory system. AIMTo explore the correlation between CEC level and severity of ARDS in patients postoperatively.METHODSBlood samples were collected from all patients on day 2 (d2) and day 5 (d5) after surgery. The control group comprised 32 healthy volunteers. Number of CECs was measured by flow cytometry, and operation time was recorded. Changes in various indexes of patients were monitored, and diagnosis of ARDS was determined based on ARDS Berlin definition. We comprised d2 CECs in different groups, correlation between operation time and d2 CECs, ARDS of different severity by d2 CECs, and predictive value of d2 CECs for ARDS in postoperative patients.RESULTSThe number of d2 CECs in the ARDS group was significantly higher than that in the healthy control group (P < 0.001). The number of d2 CECs in the ARDS group was significantly higher than that in the non-ARDS group (P < 0.001). The number of d2 CECs in the non-ARDS group was significantly higher than that in the healthy control group (P < 0.001). Operation time was positively correlated with number of CECs on d2 (rs = 0.302, P = 0.001). The number of d2 CECs in the deceased group was significantly higher than that in the improved group (P < 0.001). There was no significant difference in number of d2 CECs between patients with mild and moderate ARDS. The number of d2 CECs in patients with severe ARDS was significantly higher than that in patients with mild and moderate ARDS (P = 0.041, P = 0.037). There was no significant difference in number of d5 and d2 CECs in the non-ARDS group after admission to intensive care. The number of d5 CECs was higher than the number of d2 CECs in the ARDS improved group (P < 0.001). The number of d5 CECs was higher than the number of d2 CECs in the ARDS deceased group (P = 0.002). If the number of CECs was > 1351/mL, sensitivity and specificity of predicting ARDS were 80.8% and 78.1%, respectively. CONCLUSIONChanges in number of CECs might predict occurrence and adverse outcome of ARDS after surgery, and higher numbers of CECs indicate worse prognosis of ARDS.

Gene transfer of MRCK\u03b1 rescues lipopolysaccharide-induced acute lung injury by restoring alveolar capillary barrier function

Acute Lung Injury/Acute Respiratory Distress Syndrome (ALI/ARDS) is characterized by alveolar edema accumulation with reduced alveolar fluid clearance (AFC), alveolar-capillary barrier disruption, and substantial inflammation, all leading to acute respiratory failure. Enhancing AFC has long been considered one of the primary therapeutic goals in gene therapy treatments for ARDS. We previously showed that electroporation-mediated gene delivery of the Na+, K+-ATPase β1 subunit not only increased AFC, but also restored alveolar barrier function through upregulation of tight junction proteins, leading to treatment of LPS-induced ALI in mice. We identified MRCKα as an interaction partner of β1 which mediates this upregulation in cultured alveolar epithelial cells. In this study, we investigate whether electroporation-mediated gene transfer of MRCKα to the lungs can attenuate LPS-induced acute lung injury in vivo. Compared to mice that received a non-expressing plasmid, those receiving the MRCKα plasmid showed attenuated LPS-increased pulmonary edema and lung leakage, restored tight junction protein expression, and improved overall outcomes. Interestingly, gene transfer of MRCKα did not alter AFC rates. Studies using both cultured microvascular endothelial cells and mice suggest that β1 and MRCKα upregulate junctional complexes in both alveolar epithelial and capillary endothelial cells, and that one or both barriers may be positively affected by our approach. Our data support a model of treatment for ALI/ARDS in which improvement of alveolar-capillary barrier function alone may be of more benefit than improvement of alveolar fluid clearance.

Cytokine storm and histopathological findings in 60 cases of COVID-19-related death: from viral load research to immunohistochemical quantification of major players IL-1\u03b2, IL-6, IL-15 and TNF-\u03b1

This study involves the histological analysis of samples taken during autopsies in cases of COVID-19 related death to evaluate the inflammatory cytokine response and the tissue localization of the virus in various organs. In all the selected cases, SARS-CoV-2 RT-PCR on swabs collected from the upper (nasopharynx and oropharynx) and/or the lower respiratory (trachea and primary bronchi) tracts were positive. Tissue localization of SARS-CoV-2 was detected using antibodies against the nucleoprotein and the spike protein. Overall, we tested the hypothesis that the overexpression of proinflammatory cytokines plays an important role in the development of COVID-19-associated pneumonia by estimating the expression of multiple cytokines (IL-1β, IL-6, IL-10, IL-15, TNF-α, and MCP-1), inflammatory cells (CD4, CD8, CD20, and CD45), and fibrinogen. Immunohistochemical staining showed that endothelial cells expressed IL-1β in lung samples obtained from the COVID-19 group (p < 0.001). Similarly, alveolar capillary endothelial cells showed strong and diffuse immunoreactivity for IL-6 and IL-15 in the COVID-19 group (p < 0.001). TNF-α showed a higher immunoreactivity in the COVID-19 group than in the control group (p < 0.001). CD8 + T cells where more numerous in the lung samples obtained from the COVID-19 group (p < 0.001). Current evidence suggests that a cytokine storm is the major cause of acute respiratory distress syndrome (ARDS) and multiple organ failure and is consistently linked with fatal outcomes.

The upregulation of miR-204-3p in LPS-induced acute lung injury aggravated pulmonary endothelial cells apoptosis via targeting sulfatase 2.

Acute lung injury (ALI) results from the injury of alveolar epithelial cells and pulmonary capillary endothelial cells, with a high mortality rate ranging from 29% to 42%. Therefore, more efficient therapeutic strategies for ALI are necessary. Numerous studies revealed that miRNAs play a role in the regulation of ALI. Lipopolysaccharide (LPS) can induce an inflammatory response and has been widely applied in the establishment of the mouse ALI model. Here, we reported that miR-204-3p expression was upregulated by LPS treatment with increased cytokine secretion. LPS treatment promoted cell apoptosis, accompanied by abnormal cell structure and unobvious alveolar structure. These effects could be prevented by down-regulation of miR-204-3p, and promoted by miR-204-3p overexpression. Sulfatase 2 (SULF2) appeared to be the target of miR-204-3p predicted by TargetScan. Downregulation of miR-204-3p enhanced the protein level of SULF2, indicating that SULF2 was a target of miR-204-3p, which could negatively regulate the expression of SULF2. Thus, targeting miR-204-3p may be a potential therapeutic strategy for ALI.

Research progress of extracellular vesicle microRNA in acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are characterized by the destruction of the barrier function of alveolar epithelial cells and capillary endothelial cells and the recruitment of inflammatory cells, which leads to alveolar and interstitial edema, hyaline membrane formation and inflammatory infiltration of the lungs, etc. The mechanism is not completely defined. The current treatment plan focuses on comprehensive treatments such as ventilator support treatment, fluid management, and nutritional support, but the prognosis is still poor. Studies have shown that extracellular vesicle microRNA (miRNA) from different sources participate in regulating the function of epithelial cells, endothelial cells and phagocytes in different ways, thus aggravating or improving ALI, and have diagnostic, differential diagnosis and the therapeutic value. In this article, the mechanism, diagnostic and differerntial value of extracellular vesicle miRNA from different sources in ALI and the therapy of extracellular vesicle miRNA from stem cell in ALI are reviewed.

Expression of DUSP12 Reduces Lung Vascular Endothelial Cell Damage in a Murine Model of Lipopolysaccharide-Induced Acute Lung Injury via the Apoptosis Signal-Regulating Kinase 1 (ASK1)-Jun N-Terminal Kinase Activation (JNK) Pathway.

BackgroundAcute lung injury (ALI) results from damage to the alveolar capillary endothelial cells and can result in acute respiratory distress syndrome (ARDS). This study aimed to investigate murine lung vascular endothelial cells (MLECs) damage in a murine model of lipopolysaccharide (LPS)-induced ALI.Material/MethodsMice were injected with LPS to induce an acute lung injury model. An adenovirus transfection system was used to overexpress or knockdown DUSP12 in mice. MLECs were isolated, cultured and transfected with DUSP12-overexpressing adenovirus or with DUSP12 siRNA to knockdown DUSP12. LPS was used to establish a cell injury model. ELISA and RT-PCR were used to examine cell inflammation. LPS-induced oxidative stress was also evaluated using commercial kits.ResultsA decreased level of DUSP12 was observed in MLECs treated with LPS. DUSP12 overexpression in mice attenuated LPS-induced lung inflammation and lung injury, as reflected by reduced levels of proinflammatory cytokines. Mice with DUSP12 knockdown exhibited worsened lung inflammation and injury. In vitro, DUSP12 overexpression in endothelial cells ameliorated LPS-induced inflammation, apoptosis, and oxidative stress. DUSP12 silencing in endothelial cells aggravated LPS-induced inflammation, apoptosis, and oxidative stress. Furthermore, we found that DUSP12 directly bound to apoptosis signal-regulating kinase 1 (ASK1) to inhibit Jun N-terminal kinase activation (JNK). A JNK1/2 inhibitor and ASK1 siRNA ameliorated the exacerbating effects of DUSP12 knockdown in vitro.ConclusionsOur data demonstrated that DUSP12 suppressed MLEC injury in response to LPS insult by regulating the ASK1/JNK pathway.

Inhibition of complement C5a receptor protects lung cells and tissues against lipopolysaccharide-induced injury via blocking pyroptosis.

Acute lung injury (ALI) is the injury of alveolar epithelial cells and capillary endothelial cells caused by various factors. Complement system and pyroptosis have been proved to be involved in ALI, and inhibition of C5a/C5a receptor (C5aR) could alleviate ALI. This study aimed to investigate whether C5a/C5aR inhibition could protect against LPS-induced ALI via mediating pyroptosis. Rats were assigned into four groups: Control, LPS, LPS+W-54011 1mg/kg, and LPS+W-54011 5mg/kg. Beas-2B cells pretreated with or without C5a and W-54011, alone and in combination, were challenged with LPS+ATP. Results unveiled that LPS caused lung tissue injury and inflammatory response, increased pyroptotic and apoptotic factors, along with elevated C5a concentration and C5aR expressions. However, W-54011 pretreatment alleviated lung damage and pulmonary edema, reduced inflammation and prevented cell pyroptosis. In vitro studies confirmed that LPS+ATP reduced cell viability, promoted cell death, generated inflammatory factors and promoted expressions of pyroptosis-related proteins, which could be prevented by W-54011 pretreatment while intensified by C5a pretreatment. The co-treatment of C5a and W-54011 could blunt the effects of C5a on LPS+ATP-induced cytotoxicity. In conclusion, inhibition of C5a/C5aR developed protective effects against LPS-induced ALI and the cytotoxicity of Beas-2B cells, and these effects may depend on blocking pyroptosis.

Bilobalide Ameliorates Sepsis Induced Acute Lung Injury by Inactivating Toll-Like Receptor 4/Myeloid Differentiation Factor 88/Nuclear Factor-Kappa B Pathway

Acute lung injury refers to the injury of alveolar epithelial cells and pulmonary capillary endothelial cells caused by noncardiac factors. To better combat the disease, there is an urgent need to develop more effective drugs. Sepsis is a syndrome of systemic inflammation caused by infection, and the molecular mechanism by which sepsis induces acute lung injury has not been clearly determined. Bilobalide is a unique component of Ginkgo biloba. Although it has multiple biological functions, its role in sepsis induced acute lung injury needs further study. In this study, we found that bilobalide alleviated cecal ligation and puncture induced acute lung injury. Additionally, bilobalide regulated cecal ligation and puncture induced lung injury through toll-like receptor 4/myeloid differentiation factor 88/nuclear factor-kappa B pathway. We therefore conclude that bilobalide may be a potential drug for the treatment of sepsis induced acute lung injury.

YAP Regulates NFI/KLF5 Transcriptional and Epigenetic Networks Directing Alveolar Epithelial Cell Differentiation

Ventilation is dependent upon the pulmonary alveoli which are lined by two major epithelial cell types, alveolar type 1 and 2 (AT1) and (AT2) cells. AT1 cells are located in close apposition to alveolar capillary endothelial cells to mediate gas exchange. AT2 cells synthesize and secrete pulmonary surfactant lipids and protein and serve as progenitor cells which proliferate and differentiate to repair the alveoli after injury. Herein, we developed transgenic mice in which YAP was activated or deleted to determine its roles in alveolar epithelial cell differentiation. Organoids from YAPactive mice selectively differentiated into AT1 cells demonstrating that YAP may be required for AT1 cell differentiation in-vitro . Activation of YAP in the postnatal lung increased epithelial cell proliferation, increased numbers of AT1 cells, and caused indeterminate differentiation of subsets of alveolar cells in-vivo, inducing atypical expression of genes normally restricted to conducting airway epithelial cells. Deletion of YAP increased expression of genes associated with mature AT2 cells. In combination with altered gene expression, YAP activation caused widespread changes in chromatin accessibility and ATAC sequencing demonstrated enhanced DNA accessibility in promoters of transcription factors and predicted target genes associated with alveolar cell differentiation. YAP participated with KLF5, NFIB, and NKX2-1 to regulate alveolar epithelial cell gene expression, together activating AGER, an AT1 signature gene. YAP plays a central role in a transcriptional network regulating alveolar epithelial differentiation.

Endothelial Dysfunction and Thrombosis in Patients With COVID-19-Brief Report.

Alveolar-capillary endothelial cells can be activated by severe acute respiratory syndrome coronavirus 2 infection leading to cytokine release. This could trigger endothelial dysfunction, pyroptosis, and thrombosis, which are the vascular changes, commonly referred to as coronavirus disease 2019 (COVID-19) endotheliopathy. Thus, this study aimed to identify tissue biomarkers associated with endothelial activation/dysfunction and the pyroptosis pathway in the lung samples of patients with COVID-19 and to compare them to pandemic influenza A virus H1N1 subtype 2009 and control cases. Approach and Results: Postmortem lung samples (COVID-19 group =6 cases; H1N1 group =10 cases, and control group =11 cases) were analyzed using immunohistochemistry and the following monoclonal primary antibodies: anti-IL (interleukin)-6, anti-TNF (tumor necrosis factor)-α, anti-ICAM-1 (intercellular adhesion molecule 1), and anticaspase-1. From the result, IL-6, TNF-α, ICAM-1, and caspase-1 showed higher tissue expression in the COVID-19 group than in the H1N1 and control groups. Our results demonstrated endothelial dysfunction and suggested the participation of the pyroptosis pathway in the pulmonary samples. These conditions might lead to systemic thrombotic events that could impair the clinical staff's efforts to avoid fatal outcomes. One of the health professionals' goals should be to identify the high risk of thrombosis patients early to block endotheliopathy and its consequences.