Alveolar Epithelial Cell Damage Research Articles

The Mitochondrial-Derived Peptide MOTS-c Alleviates Radiation Pneumonitis via an Nrf2-Dependent Mechanism.

Radiation pneumonitis (RP) is a prevalent and fatal complication of thoracic radiotherapy due to the lack of effective treatment options. RP primarily arises from mitochondrial injury in lung epithelial cells. The mitochondrial-derived peptide MOTS-c has demonstrated protective effects against various diseases by mitigating mitochondrial injury. C57BL/6 mice were exposed to 20 Gy of lung irradiation (IR) and received daily intraperitoneal injections of MOTS-c for 2 weeks. MOTS-c significantly ameliorated lung tissue damage, inflammation, and oxidative stress caused by radiation. Meanwhile, MOTS-c reversed the apoptosis and mitochondrial damage of alveolar epithelial cells in RP mice. Furthermore, MOTS-c significantly inhibited oxidative stress and mitochondrial damage in MLE-12 cells and primary mouse lung epithelial cells. Mechanistically, MOTS-c increased the nuclear factor erythroid 2-related factor (Nrf2) level and promoted its nuclear translocation. Notably, Nrf2 deficiency abolished the protective function of MOTS-c in mice with RP. In conclusion, MOTS-c alleviates RP by protecting mitochondrial function through an Nrf2-dependent mechanism, indicating that MOTS-c may be a novel potential protective agent against RP.

Effects of nanoparticles on sensitivity to injury and role of autophagy in alveolar epithelial cells

Autophagy, a housekeeping mechanism, is crucial in the maintenance of normal cellular function. Although the involvement of autophagic processes is recognized in numerous diseases, it is unknown how cellular homeostasis might be affected by alterations in available autophagic activity and/or autophagic capacity. In this study, we measured autophagic flux and cellular damage in primary cultured monolayers of rat alveolar epithelial cells (AEC) exposed separately and sequentially to two different autophagy inducers. Rat AEC monolayers were exposed apically for 24 hrs to (1) polystyrene nanoparticles (PNP, 20 nm, carboxylated, near-infrared dye-labeled), (2) tunicamycin (TN, a disruptor of protein synthesis and inducer of the unfolded protein response, at 1-15 μg/mL), or (3) TN (1-15 μg/mL) after 12 hrs of PNP pre-incubation. Release of the cytoplasmic enzyme lactate dehydrogenase (LDH) was used as an indicator of cellular damage and quantified by an LDH assay from Dojindo (Rockville, MD). Autophagic flux was assessed by live cell imaging using confocal microscopy and 0.1 μM DAPRed (Dojindo; Rockville, MD) in the presence (for 1 hr) and absence of 40 μM chloroquine. Serial z sections were collected over the entire cell volume of live single cells to detect DAPRed (autophagosome) fluorescence. PNP were taken up into AEC, where their cytosolic presence induced a gradually increased autophagic flux, reaching a steady state at ~10-24 hrs. When AEC were exposed to TN alone for 24 hrs, autophagy was also activated. Cellular damage in the presence of TN, determined by increased LDH release, revealed dose-dependent injury with LD50 of 8.12 μg/mL over 24 hr TN exposure. When AEC were pre-exposed to PNP for 12 hrs and subsequently exposed to TN, increased LDH release was seen with LD50 of 3.95 μg/mL. In summary, the intracellular presence of PNP taken up from apical fluid of rat AEC monolayers activated autophagy. When cellular protein synthesis was disrupted with TN alone, autophagy was also activated. Furthermore, TN induced dose-dependent cellular damage in AEC. However, after pre-exposure to PNP, TN induced greater cellular damage observed as increased LDH release. These results suggest that autophagic capacity is limited and that pre-induction of autophagy by inhaled PNP makes AEC more susceptible to secondary injury by TN. These findings are consistent with the hypothesis that environmental stressors (e.g., ambient air nanoparticles) exert their harmful effects, at least in part, by reducing available autophagic activity/capacity, thereby causing nanoparticle-exposed AEC to be more susceptible to secondary injury. Funding: NIH; WRMPPF. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Bleomycin induces senescence and repression of DNA repair via downregulation of Rad51

BackgroundBleomycin, a potent antitumor agent, is limited in clinical use due to the potential for fatal pulmonary toxicity. The accelerated DNA damage and senescence in alveolar epithelial cells (AECs) is considered a key factor in the development of lung pathology. Understanding the mechanisms for bleomycin-induced lung injury is crucial for mitigating its adverse effects.MethodsHuman lung epithelial (A549) cells were exposed to bleomycin and subsequently assessed for cellular senescence, DNA damage, and double-strand break (DSB) repair. The impact of Rad51 overexpression on DSB repair and senescence in AECs was evaluated in vitro. Additionally, bleomycin was intratracheally administered in C57BL/6 mice to establish a pulmonary fibrosis model.ResultsBleomycin exposure induced dose- and time-dependent accumulation of senescence hallmarks and DNA lesions in AECs. These effects are probably due to the inhibition of Rad51 expression, consequently suppressing homologous recombination (HR) repair. Mechanistic studies revealed that bleomycin-mediated transcriptional inhibition of Rad51 might primarily result from E2F1 depletion. Furthermore, the genetic supplement of Rad51 substantially mitigated bleomycin-mediated effects on DSB repair and senescence in AECs. Notably, decreased Rad51 expression was also observed in the bleomycin‐induced mouse pulmonary fibrosis model.ConclusionsOur works suggest that the inhibition of Rad51 plays a pivotal role in bleomycin-induced AECs senescence and lung injury, offering potential strategies to alleviate the pulmonary toxicity of bleomycin.

Serum VEGF-A levels on admission in COVID-19 patients correlate with SP-D and neutrophils, reflecting disease severity: A prospective study

Background and objectiveThe coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in significant global morbidity and mortality. This study aimed to investigate the clinical significance of serum vascular endothelial growth factor A (VEGF-A) in COVID-19 patients and its association with disease severity and pulmonary injury. MethodsWe prospectively collected data from 71 hospitalized COVID-19 patients between June 2020 and January 2021. Patients were classified as either mild or severe based on their oxygen requirements during hospitalization. Serum VEGF-A levels were measured using an ELISA kit. ResultsIn comparison to mild cases, significantly elevated serum VEGF-A levels were observed in severe COVID-19 patients. Furthermore, VEGF-A levels exhibited a positive correlation with white blood cell count, neutrophil count, and lymphocyte count. Notably, serum surfactant protein-D (SP-D), an indicator of alveolar epithelial cell damage, was significantly higher in patients with elevated VEGF-A levels. ConclusionThese results suggest that elevated serum VEGF-A levels could serve as a prognostic biomarker for COVID-19 as it is indicative of alveolar epithelial cell injury caused by SARS-CoV-2 infection. Additionally, we observed a correlation between VEGF-A and neutrophil activation, which plays a role in the immune response during endothelial cell injury, indicating a potential involvement of angiogenesis in disease progression. Further research is needed to elucidate the underlying mechanisms of VEGF-A elevation in COVID-19.

Vitamin D3 improved hypoxia-induced lung injury by inhibiting the complement and coagulation cascade and autophagy pathway

BackgroundPulmonary metabolic dysfunction can cause lung tissue injury. There is still no ideal drug to protect against hypoxia-induced lung injury, therefore, the development of new drugs to prevent and treat hypoxia-induced lung injury is urgently needed. We aimed to explore the ameliorative effects and molecular mechanisms of vitamin D3 (VD3) on hypoxia-induced lung tissue injury.MethodsSprague–Dawley (SD) rats were randomly divided into three groups: normoxia, hypoxia, and hypoxia + VD3. The rat model of hypoxia was established by placing the rats in a hypobaric chamber. The degree of lung injury was determined using hematoxylin and eosin (H&E) staining, lung water content, and lung permeability index. Transcriptome data were subjected to differential gene expression and pathway analyses. In vitro, type II alveolar epithelial cells were co-cultured with hepatocytes and then exposed to hypoxic conditions for 24 h. For VD3 treatment, the cells were treated with low and high concentrations of VD3.ResultsTranscriptome and KEGG analyses revealed that VD3 affects the complement and coagulation cascade pathways in hypoxia-induced rats, and the genes enriched in this pathway were Fgb/Fga/LOC100910418. Hypoxia can cause increases in lung edema, inflammation, and lung permeability disruption, which are attenuated by VD3 treatment. VD3 weakened the complement and coagulation cascade in the lung and liver of hypoxia-induced rats, characterized by lower expression of fibrinogen alpha chain (Fga), fibrinogen beta chain (Fgb), protease-activated receptor 1 (PAR1), protease-activated receptor 3 (PAR3), protease-activated receptor 4 (PAR4), complement (C) 3, C3a, and C5. In addition, VD3 improved hypoxic-induced type II alveolar epithelial cell damage and inflammation by inhibiting the complement and coagulation cascades. Furthermore, VD3 inhibited hypoxia-induced autophagy in vivo and in vitro, which was abolished by the mitophagy inducer, carbonyl cyanide-m-chlorophenylhydrazone (CCCP).ConclusionVD3 alleviated hypoxia-induced pulmonary edema by inhibiting the complement and coagulation cascades and autophagy pathways.

Potential mechanisms of lung injury and repair after hexavalent chromium [Cr(VI)] aerosol whole-body dynamic exposure

Hexavalent chromium [Cr(VI)], known as "Top Hazardous Substances", poses a significant threat to the respiratory system. Nevertheless, the potential mechanisms of toxicity and the lung's repair ability after injury remain incompletely understood. In this study, Cr(VI) aerosol whole-body dynamic exposure system simulating real exposure scenarios of chromate workers was constructed to evaluate the lung injury and repair effects. Subsequently, miRNA sequencing, mRNA sequencing and metabolomics analyses on lung tissue were performed to explore the underlying mechanisms. Our results revealed that Cr(VI) exposure led to an increase in lactic dehydrogenase activity and a time-dependent decline in lung function. Notably, after 13 w of Cr(VI) exposure, alveolar hemorrhage, thickening of alveolar walls, emphysema-like changes, mitochondrial damage of alveolar epithelial cells and macrophage polarization changes were observed. Remarkably, a two-week repair intervention effectively ameliorated lung function decline and pulmonary injury. Furthermore, significant disruptions in the expressions of miRNAs and mRNAs involved in oxidative phosphorylation, glycerophospholipid metabolism and inflammatory signaling pathways were found. The two-week repair period resulted in the reversal of expression of oxidative phosphorylation related genes, and inhibited the inflammatory signaling pathways. This study concluded that the inhibition of the mitochondrial oxidative phosphorylation pathway and the subsequent enhancement of inflammatory response might be key mechanisms underlying Cr(VI) pulmonary toxicity, and timely cessation of exposure could effectively alleviate the pulmonary injury. These findings shed light on the potential mechanisms of Cr(VI) toxicity and provide crucial insights into the health protection for occupational populations exposed to Cr(VI).

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.

Attenuation of PM2.5-induced alveolar epithelial cells and lung injury through regulation of mitochondrial fission and fusion

BackgroundExposure to particulate matter (PM) with an aerodynamic diameter less than 2.5 μm (PM2.5) is a risk factor for developing pulmonary diseases and the worsening of ongoing disease. Mitochondrial fission and fusion are essential processes underlying mitochondrial homeostasis in health and disease. We examined the role of mitochondrial fission and fusion in PM2.5-induced alveolar epithelial cell damage and lung injury. Key genes in these processes include dystrophin-related protein 1 (DRP1) and optic atrophy 1 (OPA1) respectively.MethodsAlveolar epithelial (A549) cells were treated with PM2.5 (32 µg/ml) in the presence and absence of Mdivi-1 (10µM, a DRP1 inhibitor) or BGP-15 (10µM, an OPA1 activator). Results were validated using DRP1-knockdown (KD) and OPA1-overexpression (OE). Mice were injected intraperitoneally with Mdivi-1 (20 mg/kg), BGP-15 (20 mg/kg) or distilled water (control) one hour before intranasal instillation of PM2.5 (7.8 mg/kg) or distilled water for two consecutive days.ResultsPM2.5 exposure of A549 cells caused oxidative stress, enhanced inflammation, necroptosis, mitophagy and mitochondrial dysfunction indicated by abnormal mitochondrial morphology, decreased mitochondrial membrane potential (ΔΨm), reduced mitochondrial respiration and disrupted mitochondrial fission and fusion. Regulating mitochondrial fission and fusion pharmacologically using Mdivi-1 and BGP-15 and genetically using DRP1-KD and OPA1-OE prevented PM2.5-induced celluar damage in A549 cells. Mdivi-1 and BGP-15 attenuated PM2.5-induced acute lung injury in mice.ConclusionIncreased mitochondrial fission and decreased mitochondrial fusion may underlie PM2.5-induced alveolar epithelial cell damage in vitro and lung injury in vivo.

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.

SIRT3 improves alveolar epithelial cell damage caused by bronchopulmonary dysplasia through deacetylation of FOXO1.

Bronchopulmonary dysplasia (BPD) is a serious and long-term lung condition commonly observed in premature babies. Sirtuin 3 (SIRT3) has been reported to reduce pulmonary injury and pulmonary fibrosis. The present study investigated the specific role of SIRT3 in BPD by establishing hyperoxia-induced BPD rat and cell models. Hematoxylin and eosin staining was used to observe pathological changes in lung tissues. The expression levels of SIRT3 and forkhead box protein O1 (FOXO1), as well as its acetylation levels, were detected in hyperoxia-induced lung tissues and cells by Western blot analysis and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Levels of reactive oxygen species, superoxide dismutase, and malondialdehyde were assessed by using biochemical kits. Following SIRT3 overexpression, the levels of inflammatory cytokines were assessed by RT-qPCR. Apoptosis was determined by terminal deoxynucleotidyl transferase dUTP nickend labeling (TUNEL) and Western blot analysis. Upon FOXO1 knockout, cell inflammation, oxidative stress and apoptosis were evaluated again. Compared to the control group, the SIRT3 and FOXO1 expression levels were decreased and the FOXO1 acetylation levels were increased in hyperoxia-induced lung tissues and cells. In addition, SIRT3 reduced hyperoxia-induced inflammation, oxidative stress, and apoptosis in A549 cells, and inhibited FOXO1 acetylation to activate FOXO1. However, FOXO1 knockdown reversed the effects of SIRT3 overexpression in hyperoxia-induced A549 cells. SIRT3 relieved alveolar epithelial cell damage caused by BPD via deacetylation of FOXO1, suggesting that SIRT3 could be a therapeutic target in BPD.

Necrostatin-1 Alleviates Diffuse Pulmonary Haemorrhage by Preventing the Release of NETs via Inhibiting NE/GSDMD Activation in Murine Lupus.

Diffuse alveolar haemorrhage (DAH) is a rapidly developing condition owing to a lack of effective treatment and resulting in a high mortality rate in systemic lupus erythematosus (SLE). Neutrophil extracellular traps (NETs) contain numerous antigens and proinflammatory substances that directly damage the vascular endothelium and aggravate vascular inflammation, which is considered an important pathogenic factor of DAH in SLE. Therefore, blocking the release of NETs from neutrophils is an important target for the treatment of DAH in SLE. In this study, we investigated whether the inhibition of neutrophils releasing NETs could relieve DAH in SLE. Necrostatin-1 (Nec-1), a small molecule, has been reported to inhibit the release of NETs by neutrophils. In vitro experiments revealed that Nec-1 inhibited alveolar epithelial cell damage by preventing the release of NETs. Furthermore, vivo studies showed that Nec-1 alleviated lupus pulmonary haemorrhage in mice by reducing lung pathology severity, body weight, and serum inflammatory cytokine levels. Mechanistically, Nec-1 prevented NET release by inhibiting neutrophil elastase (NE) activation and N-Gasdermin D (N-GSDMD) expression. Additionally, immunohistochemistry and immunofluorescence findings showed that Nec-1 decreased NE expression in the lung tissues of mice with lupus pulmonary haemorrhage. Thus, NETs released by neutrophils contributed to the pathogenesis of DAH in SLE, and Nec-1 showed protective effects by the inhibition of NET production via the reduction of NE activation and N-GSDMD expression.

Role of Ferroptosis in Regulating the Epithelial-Mesenchymal Transition in Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis is a chronic interstitial lung disease whose pathogenesis involves a complex interaction of cell types and signaling pathways. Lung epithelial cells responding to repeated injury experience persistent inflammation and sustained epithelial-mesenchymal transition (EMT). The persistence of EMT-induced signals generates extracellular matrix accumulation, thereby causing fibrosis. Ferroptosis is a newly characterized iron-dependent non-apoptotic regulated cell death. Increased iron accumulation can increase iron-induced oxidant damage in alveolar epithelial cells. Studies have demonstrated that iron steady states and oxidation steady states play an important role in the iron death regulation of EMT. This review summarizes the role of ferroptosis in regulating EMT in pulmonary fibrosis, aiming to provide a new idea for the prevention and treatment of this disease.

Role of Mesenchymal Stem Cells and Extracellular Vesicles in Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial fibrotic disease that leads to disability and death within 5 years of diagnosis. Pulmonary fibrosis is a disease with a multifactorial etiology. The concept of aberrant regeneration of the pulmonary epithelium reveals the pathogenesis of IPF, according to which repeated damage and death of alveolar epithelial cells is the main mechanism leading to the development of progressive IPF. Cell death provokes the migration, proliferation and activation of fibroblasts, which overproduce extracellular matrix, resulting in fibrotic deformity of the lung tissue. Mesenchymal stem cells (MSCs) and extracellular vesicles (EVs) are promising therapies for pulmonary fibrosis. MSCs, and EVs derived from MSCs, modulate the activity of immune cells, inhibit the expression of profibrotic genes, reduce collagen deposition and promote the repair of damaged lung tissue. This review considers the molecular mechanisms of the development of IPF and the multifaceted role of MSCs in the therapy of IPF. Currently, EVs-MSCs are regarded as a promising cell-free therapy tool, so in this review we discuss the results available to date of the use of EVs-MSCs for lung tissue repair.

Number 2 Feibi Recipe Ameliorates Pulmonary Fibrosis by Inducing Autophagy Through the GSK-3β/mTOR Pathway.

Number 2 Feibi Recipe (N2FBR) is a traditional Chinese medicine formula for treating idiopathic pulmonary fibrosis. N2FBR inhibits H2O2-mediated oxidative stress damage in alveolar epithelial cells by increasing autophagy, as we previously demonstrated. However, it is unknown if similar mechanisms occur in vivo. We established a pulmonary fibrosis model by instilling bleomycin (BLM) from the airway to examine the effects of N2FBR on pulmonary fibrosis and investigate its probable mechanism in this work. We discovered that N2FBR treatment effectively alleviated interstitial fibrosis as well as collagen deposition, primarily in upregulating SOD, GSH-Px, T-AOC and downregulating MDA content. N2FBR also increased the expression of LC3B, Beclin-1, LAMP1, TFEB and downregulated the expression of p62, legumain. N2FBR treatment boosted the production of autophagosomes, according to the results of the TEM observation. Furthermore, we explored that N2FBR exerted its anti-oxidative stress and pro-autophagy effects via GSK-3β/mTOR signalling pathway. Therefore, these results provide further evidence for the protective effect of N2FBR in pulmonary fibrosis. Our findings could have ramifications for the development of antifibrosis therapies.

BML-111 alleviates inflammatory response of alveolar epithelial cells via miR-494/Slit2/Robo4 signalling axis to improve acute lung injury

Acute lung injury (ALI) is a common, variously induced lung cell injury with high mortality. It is also an early stage of acute respiratory distress syndrome. BML-111 is a lipoxin A4 receptor agonist that plays an important role in inflammation. However, its function on ALI remains unclear. To explore whether BML-111 is involved in ALI and its regulatory molecular mechanism, we constructed an in vitro ALI model by stimulating primary mouse alveolar epithelial cells (AECs) with lipopolysaccharide (LPS). The downstream target of microRNA (miR)-494 was predicted by Targetscan. The apoptosis and expression of inflammatory cytokines were analysed by RT-qPCR, Western blot, and ELISA. BML-111 treatment alleviated LPS-induced apoptosis and the production of inflammatory cytokines, such as tumour necrosis factor α, interleukin (IL)-6, IL-1β, in primary mouse AECs via downregulating miR-494. MiR-494 targeted and downregulated slit guidance ligand 2 (Slit2) in primary mouse AECs. BML-111 activated the Slit2/roundabout guidance receptor 4 (Robo4) axis via downregulating miR-494 to reduce LPS-induced damage in AECs. This study elucidated that miR-494 on BML-111 alleviated LPS-induced ALI in primary mouse AECs via downregulating miR-494 and subsequently activating the Slit2/Robo4 axis. These findings provided a new idea for the prevention and treatment of ALI and respiratory distress syndrome.

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.

Effect of α-tocopherol in alleviating the lipopolysaccharide-induced acute lung injury via inhibiting nuclear factor kappa-B signaling pathways

ABSTRACT Acute respiratory distress syndrome (ARDS) leads to the acute lung injury (ALI), a form of diffused alveolars injury, accompanied by severe inflammation and oxidative damage of alveolar epithelial cells. α-Tocopherol (α-TOH), one of the eight isoforms of vitamin E, is a natural antioxidant-free radical. We aimed to understand the effect of α-TOH and mechanism involved in inducing the ALI. Lipopolysaccharide (LPS) is injected into the trachea of mice to generate ALI mouse models. α-TOH was used to administrate the mice intragastrically to detect the expression of inflammatory factors and antioxidant molecules by enzyme linked immunosorbent assay, hematoxylin–eosin staining and immunohistochemical staining. Mouse alveolar epithelial cell line (MLE-12 cells) was used to determine the effect of α-TOH on alveolar epithelial cells. Inflammatory factors such as, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α shows significant increase in the lung tissues of the mice induced by LPS and reduction in the expressions of superoxide dismutase (SOD)1/2 and glutathione peroxidase (GSH-Px). After treatment with α-TOH, the inflammation and oxidative stress levels shows substantial reduction in the lung tissues of the mice. Moreover, α-TOH also increases the proliferation ability of MLE-12 cells in vitro and reduces apoptosis level. In addition, α-TOH reduces p65 phosphorylation and nuclear translocation in alveolar epithelial cells in vivo and in vitro, thus, inhibiting the activity of the nuclear factor kappa-B (NF-κB) signaling pathway. α-TOH reduces the inflammation and oxidative stress of lung tissue by inhibiting the NF-κB signaling pathway, thereby alleviating the LPS-induced ALI.

MiR-29a-3p Improves Acute Lung Injury by Reducing Alveolar Epithelial Cell PANoptosis.

Alveolar epithelial cell damage is an important determinant of the severity of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). However, the molecular mechanisms of alveolar epithelial death during the development of ALI/ARDS remain unclear. In this study, we explore the role of miR-29a-3p in ALI/ARDS and its molecular mechanism. Plasma samples were collected from healthy controls and ARDS patients. Mice were intratracheally instilled with lipopolysaccharide (LPS) to establish acute lung injury. N6-adenosine (m6A) quantification, RNA-binding protein immunoprecipitation, cell viability assay, quantitative real-time polymerase chain reaction, and western blotting were performed. We found that miR-29a-3p was down-regulated in plasma of ARDS patients and lung tissue of ALI model mice, and miR-29a-3p agomir injection down-regulated the levels of the inflammatory factors, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in the lungs, reducing alveolar epithelial cell PANoptosis as evaluated by the downregulation of Z-DNA binding protein 1 (ZBP1), gasdermin D (GSDMD), caspase-3, caspase-8, and mixed lineage kinase domain-like protein (MLKL), ultimately improving lung injury in the ALI model mice. Mechanism studies demonstrated that the knockout of methyltransferase 3 (N6-adenosine-methyltransferase complex catalytic subunit) removed the m6A modification of miR-29a-3p and reduced miR-29a-3p expression. Our findings suggest that miR-29a-3p is a potential target that can be manipulated for ALI/ARDS.

Stalling SARS-CoV2 infection with stem cells: can regenerating perinatal tissue mesenchymal stem cells offer a multi-tiered therapeutic approach to COVID-19?

The emergence of COVID-19 has created a major health crisis across the globe. Invasion of SARS-CoV-2 into the lungs causes acute respiratory distress syndrome (ARDS) that result in the damage of lung alveolar epithelial cells. Currently, there is no standard treatment available to treat the disease and the resultant lung scarring is irreversible even after recovery. This has prompted researchers across the globe to focus on developing new therapeutics and vaccines for the treatment and prevention of COVID-19. Mesenchymal stem cells (MSCs) have emerged as an efficient drug screening platform and MSC-derived organoids has found applications in disease modeling and drug discovery. Perinatal tissue derived MSC based cell therapies have been explored in the treatment of various disease conditions including ARDS because of their enhanced regenerative and immunomodulatory properties. The multi-utility properties of MSCs have been described in this review wherein we discuss the potential use of MSC-derived lung organoids in screening of novel therapeutic compounds for COVID-19 and also in disease modeling to better understand the pathogenesis of the disease. This article also summarizes the rationale behind the development of MSC-based cell- and cell-free therapies and vaccines for COVID-19 with a focus on the current progress in this area. With the pandemic raging, an important necessity is to develop novel treatment strategies which will not only alleviate the disease symptoms but also avoid any off-target effects which could further increase post infection sequelae. Naturally occurring mesenchymal stem cells could be the magic bullet which fulfil these criteria.

TBHQ alleviates pyroptosis and necroptosis in chicken alveolar epithelial cells induced by fine particulate matter from broiler houses

Fine particulate matter (PM2.5) from poultry houses has adverse effects on the health of animals and workers. Tert-butylhydroquinone (TBHQ), an antioxidant, is widely used in feed additives. The present study investigated the effects of TBHQ on broiler house PM2.5-induced damage in chicken primary alveolar epithelial cells (AECII) extracted from 16-day-old chicken embryos using the method of differential adhesion. AECII were exposed to PM2.5 and TBHQ alone or in combination, and then, cell membrane integrity, pyroptosis, and necroptosis were detected. Our results showed that PM2.5 from broiler houses caused cell rupture and loss of cell membrane integrity. This result was confirmed by the obvious increases in lactate dehydrogenase (LDH) release and propidium iodide (PI)-positive cells compared to the control group. In addition, the intracellular reactive oxygen species (ROS) levels and the expression levels of pyroptosis-related genes (NLRP3, IL-18, IL-1β) and necroptosis-related genes (RIPK3) were also significantly enhanced. However, TBHQ significantly inhibited intracellular ROS, improved cell viability, and reduced the release of LDH and the number of PI-positive cells compared to those in the PM2.5 group. The expression levels of pyroptosis-related genes (Caspase-1, NLRP3, IL-18, IL-1β) and necroptosis-related genes (RIPK3) were also significantly decreased in the co-treatment group. In summary, these results indicated that TBHQ can alleviate PM2.5-mediated cell pyroptosis and necroptosis in chicken AECII and provide a basis for overcoming the danger that air pollutants from broiler houses pose to the health of chickens.