Alveolar Epithelial Cell Injury Research Articles

Resveratrol Attenuates Hyperoxia Lung Injury in Neonatal Rats by Activating SIRT1/PGC-1α Signaling Pathway.

Our previous study showed that resveratrol (Res) attenuates apoptosis and mitochondrial dysfunction in alveolar epithelial cell injury induced by hyperoxia by activating the SIRT1/PGC-1α signaling pathway. In the present study, we investigated whether Res protects against hyperoxia-induced lung injury in neonatal rats by activating SIRT1/PGC-1α signaling pathway. Naturally delivered neonatal rats were randomly divided into six groups: normoxia + normal saline, normoxia + dimethyl sulfoxide (DMSO), normoxia + Res, hyperoxia + normal saline, hyperoxia + DMSO, and hyperoxia + Res. Lung tissue samples were collected on postnatal days 1, 7, and 14. Hematoxylin and eosin staining was used to evaluate lung development. Dual-immunofluorescence staining, real-time polymerase chain reaction, and western blotting were used to evaluate the levels of silencing information regulator 2-related enzyme 1 (SIRT1), peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α), nuclear respiratory factor 1 (Nrf1), Nrf2, transcription factor A (TFAM) and citrate synthase, the number of mitochondrial DNA (mtDNA) and mitochondria, the integrity of mtDNA, and the expression of TFAM in mitochondria. We found that hyperoxia insulted lung development, whereas Res attenuated the hyperoxia lung injury. Res significantly upregulated the levels of SIRT1, PGC-1α, Nrf1, Nrf2, TFAM, and citrate synthase; promoted TFAM expression in the mitochondria; and increased the copy number of ND1 and the ratio of ND4/ND1. Our data suggest that Res attenuates hyperoxia-induced lung injury in neonatal rats, and this was achieved, in part, by activating the SIRT1/PGC-1α signaling pathway to promote mitochondrial biogenesis. · Hyperoxia insulted lung development in neonatal rats.. · Resveratrol promoted mitochondrial biogenesis to attenuate hyperoxia lung injury in neonatal rats.. · Resveratrol, at least in part, promoted mitochondrial biogenesis by activating the SIRT1/PGC-1α signaling pathway..

The Reaction Pathway of miR-30c-5p Activates Lipopolysaccharide Promoting the Course of Traumatic and Hemorrhagic Shock Acute Lung Injury.

Acute lung injury (ALI) is an acute hypoxic respiratory failure caused by diffuse inflammatory injury in alveolar epithelial cells during severe infection, trauma, and shock. Among them, trauma/hemorrhagic shock (T/HS) is the main type of indirect lung injury. Despite a great number of clinical studies, indirect factor trauma/hemorrhagic shock to the function and the mechanism in acute lung injury is not clear yet. Therefore, it is still necessary to carry on relevant analysis in order to thoroughly explore its molecular and cellular mechanisms and the pathway of disease function. In our research, we aimed to identify potential pathogenic genes and do modular analysis by downloading disease-related gene expression profile data. And our dataset is from the NCBI-GEO database. Then, we used the Clusterprofiler R package, GO function, and KEGG pathway enrichment analysis to analyze the core module genes. In addition, we also identified key transcription factors and noncoding RNAs. Based on the high degree of interaction of potential pathogenic genes and their involved functions and pathways, we identified 17 dysfunction modules. Among them, up to 9 modules significantly regulate the response to bacterial-derived molecules, and the response to lipopolysaccharide and other related functional pathways that mediate disease development. In addition, miR-290, miR-30c-5p, miR-195-5p, and miR-1-3p-based ncRNA and Jun, Atf1, and Atf3-based transcription factors have a total of 80 transcription drivers for functional modules. In summary, this study confirmed that miR-30c-5p activates lipopolysaccharide response pathway to promote the pathogenesis of ALI induced by hemorrhagic shock. This result can be an important direction for further research on related deepening diseases such as acute respiratory distress syndrome (ARDS). It further provides a piece of scientific medical evidence for revealing the pathogenic principle and cure difficulty of acute lung injury and also provides important guidance for the design of therapeutic strategies and drug development.

Luteolin attenuates the pathogenesis of Staphylococcus aureus by interfering with the agr system

Staphylococcus aureus is a serious human pathogen that causes a wide variety of infectious diseases with high morbidity and mortality. Luteolin was recently shown to inhibit biofilm formation and reduce the production of virulence factors and the transcription of agrA in S. aureus. Given the broad impacts of the agr quorum-sensing system on the biofilm formation and virulence factors of S. aureus, this study aimed to investigate the effects of luteolin on the agr system and pathogenicity of S. aureus. Here, we show that at subminimal inhibitory concentrations (sub-MICs) that have no effect on bacterial growth, luteolin can markedly inhibit the adhesion and biofilm formation of both wild-type (WT) and agr mutant strains of S. aureus strain Newman. The hemolytic activity and toxin protein levels were markedly decreased in the culture supernatants of luteolin-treated WT strain but not the luteolin-treated agr mutant strain. qRT–PCR analysis showed that upon luteolin treatment, the expression of genes involved in virulence and biofilm formation was downregulated in the WT S. aureus strain, and the inefficacy of luteolin with respect to the virulence factors of only the agr mutant confirmed the agr-mediated antivirulence potential of luteolin. Furthermore, treatment with sub-MIC luteolin attenuated human alveolar epithelial A549 cell injury caused by the WT Newman strain and protected mice from pneumonia caused by the WT strain, but these effects were not observed with the agr mutant strain. These findings indicate that luteolin is a promising compound that interferes with the agr system and can be developed into novel therapeutic drugs against S. aureus infections.

Number 2 Feibi Recipe Inhibits H2O2-Mediated Oxidative Stress Damage of Alveolar Epithelial Cells by Regulating the Balance of Mitophagy/Apoptosis

Reactive oxygen species (ROS)-mediated alveolar epithelial cell (AEC) injury and apoptosis are considered to be the initiating link of idiopathic pulmonary fibrosis (IPF), and protecting AECs can alleviate IPF. This study aimed to explore the protective effect of number 2 Feibi recipe (FBR-2) medicated serum on H2O2-mediated oxidative stress injury in AECs and further explore its mechanism. We found that FBR-2 can regulate downstream antioxidant enzymes expression by activating nuclear factor erythroid 2-related factor 2 (Nrf2), reducing the level of intracellular ROS, protecting mitochondrial function and improving cell survival. FBR-2 can also activate mitophagy through the PINK1/Parkin pathway. Moreover, FBR-2 can inhibit apoptosis by blocking the mitochondrial apoptosis mechanism. In summary, these data indicate that FBR-2 medicated serum can inhibit H2O2-mediated oxidative stress damage in AECs by regulating the balance of mitophagy/apoptosis. This study provides new evidence for the antifibrotic effect of FBR-2 and provides new drug candidates for the clinical treatment of IPF.

Therapeutic effects of eperisone on pulmonary fibrosis via preferential suppression of fibroblast activity

Although the exact pathogenesis of idiopathic pulmonary fibrosis (IPF) is still unknown, the transdifferentiation of fibroblasts into myofibroblasts and the production of extracellular matrix components such as collagen, triggered by alveolar epithelial cell injury, are important mechanisms of IPF development. In the lungs of IPF patients, apoptosis is less likely to be induced in fibroblasts than in alveolar epithelial cells, and this process is involved in the pathogenesis of IPF. We used a library containing approved drugs to screen for drugs that preferentially reduce cell viability in LL29 cells (lung fibroblasts from an IPF patient) compared with A549 cells (human alveolar epithelial cell line). After screening, we selected eperisone, a central muscle relaxant used in clinical practice. Eperisone showed little toxicity in A549 cells and preferentially reduced the percentage of viable LL29 cells, while pirfenidone and nintedanib did not have this effect. Eperisone also significantly inhibited transforming growth factor-β1-dependent transdifferentiation of LL29 cells into myofibroblasts. In an in vivo study using ICR mice, eperisone inhibited bleomycin (BLM)-induced pulmonary fibrosis, respiratory dysfunction, and fibroblast activation. In contrast, pirfenidone and nintedanib were less effective than eperisone in inhibiting BLM-induced pulmonary fibrosis under this experimental condition. Finally, we showed that eperisone did not induce adverse effects in the liver and gastrointestinal tract in the BLM-induced pulmonary fibrosis model. Considering these results, we propose that eperisone may be safer and more therapeutically beneficial for IPF patients than current therapies.

GSDMD-miR-223-NLRP3 axis involved in B(a)P-induced inflammatory injury of alveolar epithelial cells

Benzo(a)pyrene [B(a)P], a ubiquitous environmental pollutant, causes lung inflammatory damage. Pyroptosis，a new inflammation-dependent programmed cell death, happened when pyroptosis-related GSDMD is activated mediated by NLRP3 inflammasome. microRNA-223 (miRNA-223) is involved in inflammatory diseases by regulating NLRP3. However, whether GSDMD regulate NLRP3 inflammasome through miR-223 in B(a)P induced lung inflammatory injury remain unknown. In this study, alveolar epithelial cells (A549) were stimulated with 0, 2, 4, 8 μM B(a)P for 12 h or 24 h. The inflammatory injury and pyroptosis were determined. And the activation of NLRP3 inflammasomes and the level of miRNA-223 were detected. Then, the change of inflammatory injury and activation of NLRP3 inflammasomes in B(a)P-induced A549 cells were detected after inhibiting of GSDMD or miR-223 using siRNA-GSDMD (siGSDMD) or miR-223 inhibitor, respectively. Our results indicated that after B(a)P exposure, TNF-α and IL-6 in the supernatant were increased. Transmission electron microscope (TEM) results showed that A549 cells were obviously swollen and the cell membrane ruptured. Hoechest33342/PI staining showed that pyroptosis occurred. NLRP3, IL-1β, IL-18, GSDMD, GSDMD-N, pro caspase-1 and cleaved caspase-1 were significantly increased. Additionally, after transfecting with siGSDMD in B(a)P-induced A549 cells, the expression level of miR-223 was significantly increased. But IL-6 and TNF-α in the supernatant, the expression of NLRP3, IL-1β, IL-18 and cleaved caspase-1 protein were also decreased. And after inhibiting miR-223 in B(a)P-induced A549 cells, the expression of TNF-α and IL-6 in the supernatant, the protein expression of NLRP3, IL-1β, IL-18 and cleaved caspase-1 were increased. In conclusion, GSDMD may regulate NLRP3 inflammasome through miR-223, which is involved in B(a)P induced inflammatory damage in A549 cells.

ETS1 Ameliorates Hyperoxia-Induced Alveolar Epithelial Cell Injury by Regulating the TGM2-Mediated Wnt/β-Catenin Pathway.

Bronchopulmonary dysplasia (BPD) is a chronic lung disease that affects newborns who need oxygen therapy, and high-concentration oxygen therapy may cause neonatal morbidity and mortality in newborns. E26 oncogene homologue 1 (ETS1) and transglutaminase 2 (TGM2) have been reported to be associated with lung cell injury. However, the mechanism of ETS1 in regulating BPD is still unclear. Hyperoxia-induced A549 cells to simulate hyperoxia-induced alveolar epithelial cell injury. MTT assays and colony formation assays were performed to investigate the proliferation of A549 cells. Flow cytometry was carried out to quantify the apoptosis of A549 cells. The expression levels of ETS1 and TGM2 were quantified by qRT-PCR. The protein expression levels of ETS1, TGM2, β-catenin, c-Jun and MET were measured by western blot. Overexpression of ETS1, overexpression of TGM2, overexpression of ETS1 with downregulation of TGM2 and overexpression of TGM2 with inhibition of Wnt/β-catenin pathway were performed to investigate the role of ETS1, TGM2 and Wnt/β-catenin pathways in hyperoxia-induced alveolar epithelial cell injury. Hyperoxia decreased the proliferation and promoted the apoptosis of cells in a time-dependent manner. Moreover, overexpression of ETS1 rescued the effect of hyperoxia on proliferation and apoptosis. In addition, overexpression of TGM2 participated in the regulation of hyperoxia-induced proliferation and apoptosis. ETS1 regulated hyperoxia-induced alveolar epithelial cell injury through the Wnt/β-catenin pathway via TGM2. ETS1 ameliorates hyperoxia-induced alveolar epithelial cell injury through the TGM2-mediated Wnt/β-catenin pathway.

Pathogenic Mechanisms Underlying Idiopathic Pulmonary Fibrosis.

The pathogenesis of idiopathic pulmonary fibrosis (IPF) involves a complex interplay of cell types and signaling pathways. Recurrent alveolar epithelial cell (AEC) injury may occur in the context of predisposing factors (e.g., genetic, environmental, epigenetic, immunologic, and gerontologic), leading to metabolic dysfunction, senescence, aberrant epithelial cell activation, and dysregulated epithelial repair. The dysregulated epithelial cell interacts with mesenchymal, immune, and endothelial cells via multiple signaling mechanisms to trigger fibroblast and myofibroblast activation. Recent single-cell RNA sequencing studies of IPF lungs support the epithelial injury model. These studies have uncovered a novel type of AEC with characteristics of an aberrant basal cell, which may disrupt normal epithelial repair and propagate a profibrotic phenotype. Here, we review the pathogenesis of IPF in the context of novel bioinformatics tools as strategies to discover pathways of disease, cell-specific mechanisms, and cell-cell interactions that propagate the profibrotic niche.

Acacetin Alleviates Listeria monocytogenes Virulence Both In Vitro and In Vivo via the Inhibition of Listeriolysin O.

Listeria monocytogenes is a ubiquitous Gram-positive foodborne pathogen that is responsible for listeriosis in both humans and several animal species. The bacterium secretes a pore-forming cholesterol-dependent cytolysin, listeriolysin O (LLO), a major virulence factor involved in the activation of cellular processes. The ability of LLO to lyse erythrocytes is a measure of LLO activity. We used hemolytic activity assay to screen the LLO inhibitors. Acacetin was found to be an LLO inhibitor, which is a di-hydroxy and mono-methoxy flavone present in various plants, including Black locust, Damiana, and Silver birch. As the features of acacetin are of low toxicity and have less acquired resistance, it comes to a hotspot in drug development. In our study, we report that acacetin antagonized the hemolytic activity of L. monocytogenes culture supernatants and purified LLO by directly interfering with the formation of oligomers without inhibiting the bacterial growth and the expression of LLO. Acacetin also relieved the injury of alveolar epithelial cells by inhibiting LLO activity. Further, acacetin significantly promoted the clearance of L. monocytogenes and alleviated the histopathological damage, thereby raising survival rate, which conferred mice with effective protection against L. monocytogenes infection. Using molecular docking and dynamics simulation, we further proved the mechanism of acacetin antagonizing LLO pore-forming activity by direct binding to the second membrane-inserting helix bundle (HB2) of LLO domain 3. These data suggested that acacetin recedes the virulence of L. monocytogenes both in vivo and in vitro, and this study provided a promising candidate and potential alternative for the prevention and treatment of L. monocytogenes infections.

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.

Depression of lncRNA MINCR antagonizes LPS-evoked acute injury and inflammatory response via miR-146b-5p and the TRAF6-NFkB signaling

BackgroundInflammation plays an important role in the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). The long non-coding RNA (lncRNA) MINCR is closely related to inflammation injury. This study was performed to explore the protective effects and mechanisms of MINCR in lipopolysaccharide (LPS)-induced lung injury and inflammation.MethodsThe expression levels of MINCR and miR-146b-5p in lung tissue status were detected by using quantitative real-time polymerase chain reaction (qRT-PCR), hematoxylin and eosin staining, immunohistochemical staining, and terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Enzyme-linked immunosorbent assay and Western blotting analysis were used to detect the expression of inflammatory factors such as tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-10 in lung tissue. The relationship between MINCR, miR-146b-5p, and TRAF6 was explored using bioinformatics analysis and luciferase assay.ResultsThe expression levels of MINCR were increased in a mouse model of LPS-induced ALI and small airway epithelial cells (SAECs). shMINCR resulted in increased cell viability and decreased apoptosis, which protected against LPS-induced cell damage. shMINCR can inhibit the formation of neutrophil extracellular traps, neutrophil numbers, myeloperoxidase activity, and the production of inflammatory cytokines IL-6, IL-1β, and TNF-α induced by LPS. The silencing of miR-146b-5p reversed the effects of MINCR on LPS-induced lung damage. Sh-MINCR decreased the expression levels of TRAF6 and p-P65 in LPS-induced SAECs and lung tissues. Co-transfection of sh-MINCR with miR-146b-5p inhibitor reversed the effect of sh-MINCR on the expression of TRAF6 and p-P65.ConclusionsMINCR may induce alveolar epithelial cell injury and inflammation and aggravate the progression of ALI/ARDS through miR-146b-5p and TRAF6/NF-κB pathways, which would provide a promising target for the treatment of ALI/ARDS.

Water Extract of Gallnut Reduces the Injury of Alveolar Epithelial Cells Induced by Streptococcus pneumoniae by Up-Regulating miRNA-338-3p

Streptococcus pneumoniae (S. pneumoniae) is the primary pathogen causing pneumonia, in addition to lobar pneumonia, meningitis, bronchitis, and other diseases. Inhibiting the apoptosis and inflammation of alveolar epithelial cells is essential for the treatment of pneumonia caused by S. pneumoniae. Traditional Chinese medicine has the characteristics of multiple components, multiple targets, and few adverse reactions. It is recognized by doctors and patients in the treatment of pneumonia and other diseases. We conducted this study to explore the effect of the water extract of gallnut on alveolar epithelial cells affected by S. pneumoniae. Studies have found that the water extract of gallnut can increase the optical density value, Bcl-2 protein expression, IL-10 content, and miRNA-338-3p levels of alveolar epithelial cells affected by S. pneumoniae. Additionally, it can reduce the rate of cell apoptosis, Bax protein expression, and IL-6 content. Further, its effect is dose-dependent: the higher the concentration of gallnut water extract, the more evident its effect on alveolar epithelial cells. Through nano PCR detection, it was found that overexpression of miRNA-338-3p can increase the activity of alveolar epithelial cells affected by S. pneumoniae and promote cell growth. Knockdown of miRNA-338-3p reduced the impact of the water extract of gallnut on the growth of alveolar epithelial cells and the expression of inflammatory factors affected by S. pneumoniae. Therefore, our findings suggest that the water extract of gallnut could inhibit the apoptosis of alveolar epithelial cells affected by S. pneumoniae by up-regulating the expression of miRNA-338-3p.

IL-23 amplifies the epithelial-mesenchymal transition of mechanically conditioned alveolar epithelial cells in rheumatoid arthritis-associated interstitial lung disease through mTOR/S6 signaling.

Epithelial-mesenchymal transition (EMT) creates an environment facilitating fibrosis following alveolar epithelial cell injury. IL-23 has important roles in chronic autoimmune conditions like rheumatoid arthritis (RA), but its role in the interstitial lung disease that affects patients with RA is unclear. This study aimed to determine the profibrogenic role of IL-23 on somatic alveolar type I (ATI) epithelial cells. Primary ATI cells were isolated from rats and cultured on plastic dishes for 1-3 wk. After prolonged culture (≥14 days) on rigid culture dishes, primary ATI cells gradually acquired a mesenchymal phenotype, identified by decreased expression of caveolin-1, and reorganization of F-actin cytoskeleton, indicating the initiation of EMT by matrix stiffness. To determine how IL-23 promotes EMT in vitro, transitioning ATI cells, cultured on a stiff substrate for ≥14 days were stimulated with IL-23. The EMT phenotype was significantly enhanced by IL-23, which upregulated α-smooth muscle actin (α-SMA), collagen I/III protein, and decreased caveolin-1. Furthermore, IL-23 significantly promoted cell invasion, as well as apoptotic resistance on transitioning ATI cells. Mechanistically, IL-23-induced EMT was mammalian target of rapamycin/ribosomal protein S6 (mTOR/S6) signaling dependent and reversible by rapamycin. Transcriptional sequencing analysis of human lung fibrosis biopsy tissue revealed key roles for IL-23 in rheumatoid arthritis-associated interstitial lung disease (RA-ILD). This result was further validated by significantly upregulated IL-23 expression at the mRNA level in RA-ILD lung sections. Notably, transitioning ATI epithelial cells were abundantly detected in RA-ILD tissue. Taken together, these data support a role for IL-23 in the pathogenesis of RA lung fibrosis by promoting EMT in alveolar epithelial cells through mTOR/S6 signaling.

JMJD3 deficiency alleviates lipopolysaccharide‑induced acute lung injury by inhibiting alveolar epithelial ferroptosis in a Nrf2‑dependent manner.

Acute respiratory distress syndrome (ARDS) is a deadly illness which presents with severe hypoxemia as well as diffuse alveolar damage. Jumonji domain‑containing3 (JMJD3), which belongs to the UTX/UTY JmjC‑domain protein subfamily, is involved in infection, development, aging and immune disorders. However, the role of JMJD3 in acute lung injury (ALI) is still unclear. The present study explored the roles and potential mechanisms of JMJD3 in ALI. Alveolar epithelial cell‑specific knockout of JMJD3 mice and A549 alveolar epithelial cells were used to investigate the function of JMJD3 in ALI. Lipopolysaccharide (LPS) was used to establish an invivo and invitro ALI model. The expression of JMJD3 in murine lung tissue and alveolar epithelial cells was detected. Pathological injury of lung tissue and alveolar epithelial cells was also investigated following inhibition of JMJD3. The results showed that JMJD3 expression was significantly increased in murine lung tissues and in A549 cells following LPS stimulation. JMJD3‑deficient mice in alveolar epithelial cells exhibited alleviated lung pathological injury and ferroptosis following h stimulation. Mechanistically, it was found that JMJD3 knockout could increase the expression of nuclear factor erythroid‑2‑related factor‑2 (Nrf2) in lung tissues challenged with h. However, Nrf2 overexpression by adenovirus could further enhance the anti‑ferroptotic effect from JMJD3 silence in h‑treated A549 cells. Taken together, the present study revealed that JMJD3 deficiency may relieve LPS‑induced ALI by blocking alveolar epithelial ferroptosis in a Nrf2‑dependent manner, which may serve as a novel therapeutic target against ALI.

Extracellular HSP90α Interacts With ER Stress to Promote Fibroblasts Activation Through PI3K/AKT Pathway in Pulmonary Fibrosis.

Pulmonary fibrosis is characterized by alveolar epithelial cell injury, lung fibroblast proliferation, differentiation, and extracellular matrix (ECM) deposition. Our previous study indicated that extracellular HSP90α (eHSP90α) promotes pulmonary fibrosis by activating the MAPK signaling pathway. Thus, treatment with 1G6-D7 (a selective HSP90α monoclonal antibody) to antagonize eHSP90α could effectively ameliorate fibrosis. This study aimed to elucidate the mechanism underlying the effects of eHSP90α in pulmonary fibrosis by focusing on its link with endoplasmic reticulum (ER) stress. Our results showed that eHSP90α promoted lung fibroblast differentiation by activating ER stress. Treatment with the ER stress inhibitor tauroursodeoxycholate (TUDCA) or glucose-regulated protein 78 kDa (GRP78) depletion significantly abrogated the effect of eHSP90α on ER stress and fibroblast activation. In addition, eHSP90α induced ER stress in fibroblasts via the phosphoinositide-4,5-bisphosphate 3-kinase (PI3K)-protein kinase B (AKT) signaling pathway, which could be blocked by the PI3K/AKT inhibitor LY294002, and blockade of eHSP90α by 1G6-D7 markedly inhibited ER stress in the model, indicating preventive and therapeutic applications. Intriguingly, we observed that TUDCA effectively reduced the secretion of eHSP90α in vitro and in vivo. In conclusion, this study shows that the interaction between eHSP90α and ER stress plays a crucial role in pulmonary fibrosis, indicating a positive feedback in lung fibroblasts. Targeting eHSP90α and alleviating fibroblast ER stress may be promising therapeutic approaches for pulmonary fibrosis.

Role of the SENP1–SIRT1 pathway in hyperoxia-induced alveolar epithelial cell injury

Bronchopulmonary dysplasia (BPD) is a common complication in preterm infants, and its main pathogenesis partly involves oxidative stress. A large number of studies have shown that silent information regulator 1 (SIRT1) plays a protective role in oxidative stress. SUMO-specific protease 1 (SENP1) is vital in the nucleoplasmic distribution of SIRT1 under stress. However, whether the SENP1–SIRT1 pathway is involved in the hyperoxic lung injury is unknown. Therefore, this study aimed to explore the role and related mechanisms of the SENP1–SIRT1 pathway in hyperoxic lung injury. Peripheral blood mononuclear cells (PBMCs) from infants with BPD and SENP1-silenced alveolar epithelial cells were used as research models. PBMCs were isolated from the peripheral blood of premature infants. Next, the SENP1-silenced human alveolar epithelial cells were used to verify the role of the SENP1–SIRT1 pathway in vitro. The results indicated that the ROS level and the mRNA and protein expression of SENP1 increased in PBMCs of infants with BPD, but the expression of SIRT1 decreased in the nucleus and increased in the cytoplasm, and then the expression of acetyl-p53 (Ac-p53) increased. In the hyperoxic alveolar epithelial cell injury model, it seemed that hyperoxia could induce the same variation trend in the SENP1–SIRT1 pathway as in infants with BPD and then increased the expression of Ac-p53 and BAX, and cell apoptosis. Furthermore, silencing SENP1 could alleviate these hyperoxia-induced changes. These results suggested that SENP1 played an important role in hyperoxia-induced lung injury. It could regulate the expression and nucleoplasmic distribution of SIRT1 to inhibit its deacetylase activity, and then promoted cell apoptosis. Hence, SENP1 may become a potential intervention target of BPD in the future.

RhKGF-2 Attenuates Smoke Inhalation Lung Injury of Rats via Activating PI3K/Akt/Nrf2 and Repressing FoxO1-NLRP3 Inflammasome.

Smoke inhalation injury is an acute pathological change caused by thermal stimulation or toxic substance absorption through respiratory epithelial cells. This study aims to probe the protective effect and mechanism of recombinant human keratinocyte growth factor 2 (rhKGF-2) against smoke inhalation-induced lung injury (SILI) in rats. The SILI was induced in rats using a smoke exposure model, which were then treated with rhKGF-2. The rat blood was collected for blood-gas analysis, and the levels of inflammatory factors and oxidative stress markers in the plasma were measured. The rat lung tissues were collected. The pathological changes and cell apoptosis were determined by hematoxylin-eosin (HE) staining and TdT-mediated dUTP nick end labeling (TUNEL) assay, and the PI3K/Akt/Nrf2/HO-1/NQO1, and FoxO1-NLRP3 inflammasome expression were verified by western blot (WB). Both of the human alveolar epithelial cell (HPAEpiC) and primary rat alveolar epithelial cell were exposed to lipopolysaccharide (LPS) for making in-vitro alveolar epithelial cell injury model. After treatment with rhKGF-2, GSK2126458 (PI3K inhibitor) and AS1842856 (FoxO1 inhibitor), the cell viability, apoptosis, inflammation, oxidative stress, reactive oxygen species (ROS), PI3K/Akt/Nrf2, HO-1/NQO1, and FoxO1-NLRP3 in HPAEpiC and primary rat alveolar epithelial cell were examined. The data suggested that rhKGF-2 reduced LPS-induced HPAEpiC cell and primary rat alveolar epithelial cell apoptosis and the expression of inflammatory factors and oxidative stress factors. Moreover, rhKGF-2 improved the blood gas and alleviated SILI-induced lung histopathological injury in vivo via repressing inflammation, NLRP3 inflammasome activation and oxidative stress. Mechanistically, rhKGF-2 activated PI3K/Akt pathway, enhanced Nrf2/HO-1/NQO1 expression, and attenuated FoxO1-NLRP3 inflammasome both in vitro and in vivo. However, pharmaceutical inhibition of PI3K/Akt pathway attenuated rhKGF-2-mediated protective effects against SILI, while suppressing FoxO1 promoted rhKGF-2-mediated protective effects. Taken together, this study demonstrated that rhKGF-2 mitigated SILI by regulating the PI3K/Akt/Nrf2 pathway and the FoxO1-NLRP3 axis, which provides new reference in treating SILI.

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.

Liproxstatin-1 alleviates bleomycin-induced alveolar epithelial cells injury and mice pulmonary fibrosis via attenuating inflammation, reshaping redox equilibrium, and suppressing ROS/p53/α-SMA pathway

With undetermined etiology and limited treatment option, idiopathic pulmonary fibrosis (IPF) an age related disease is extremely lethal. Persistent injury of epithelial cells, abnormal activation of fibroblasts/myofibroblasts, and superabundant deposition of extracellular matrix protein pathologically characterize IPF. Redox imbalance is reported to play a vital role in both IPF development and senescence. This study aim to investigate whether and how Liproxstatin-1 (Lip-1), a strong lipid autoxidation inhibitor, regulates bleomycin (BLM) induced pulmonary fibrosis both in vivo and in vitro. It’s demonstrated that Lip-1 exerted a potent anti-fibrotic function in BLM-induced mice pulmonary fibrosis via alleviating inflammatory, reshaping redox equilibrium, and ameliorating collagen deposition. Lip-1 reduced the level of reactive oxygen species (ROS) and methane dicarboxylic aldehyde (MDA), promoted the expression of glutathione (GSH), catalase (CAT), and total superoxide dismutase (T-SOD) after BLM treatment. Moreover, in vitro experiments verified that Lip-1 protected A549 cells from BLM-induced injury and fibrosis. Lip-1 seemed to attenuate BLM-induced fibrosis by targeting ROS/p53/α-SMA signaling both in vivo and in vitro. In summary, this study demonstrates that Lip-1 administration performs a protective role in against pulmonary fibrosis and lights up the potential of Lip-1 treatment for patient with IPF in future.

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.