OBJECTIVE: To explore the effect of bear bile powder (BBP) on acute lung injury (ALI) and the underlying mechanism. METHODS: The chemical constituents of BBP were analyzed by ultra-high-pressure liquid chromatography-mass spectrometry (UPLC-MS). After 7 days of adaptive feeding, 50 mice were randomly divided into 5 groups by a random number table (n=10): normal control (NC), lipopolysaccharide (LPS), dexamethasone (Dex), low-, and high-dose BBP groups. The dosing cycle was 9 days. On the 12th and 14th days, 20 µL of Staphylococcus aureus solution (bacterial concentration of 1 × 10^-7 CFU/mL) was given by nasal drip after 1 h of intragastric administration, and the mice in the NC group was given the same dose of phosphated buffered saline (PBS) solution. On the 16th day, after 1 h intragastric administration, 100 µL of LPS solution (1 mg/mL) was given by tracheal intubation, and the same dose of PBS solution was given to the NC group. Lung tissue was obtained to measure the myeloperoxidase (MPO) activity, the lung wet/dry weight ratio and expressions of CD14 and other related proteins. The lower lobe of the right lung was obtained for pathological examination. The concentrations of inflammatory cytokines including interleukin (IL)-6, tumour necrosis factor α (TNF-α ) and IL-1β in the bronchoalveolar lavage fluid (BALF) were detected by enzyme linked immunosorbent assay, and the number of neutrophils was counted. The colonic contents of the mice were analyzed by 16 sRNA technique and the contents of short-chain fatty acids (SCFAs) were measured by gas chromatograph-mass spectrometer (GC-MS). RESULTS: UPLC-MS revealed that the chemical components of BBP samples were mainly tauroursodeoxycholic acid and taurochenodeoxycholic acid sodium salt. BBP reduced the activity of MPO, concentrations of inflammatory cytokines, and inhibited the expression of CD14 protein, thus suppressing the activation of NF-κB pathway (P<0.05). The lung histopathological results indicated that BBP significantly reduced the degree of neutrophil infiltration, cell shedding, necrosis, and alveolar cavity depression. Moreover, BBP effectively regulated the composition of the intestinal microflora and increased the production of SCFAs, which contributed to its treatment effect (P<0.05). CONCLUSIONS BBP alleviates lung injury in ALI mouse through inhibiting activation of NF-κB pathway and decreasing expression of CD14 protein. BBP may promote recovery of ALI by improving the structure of intestinal flora and enhancing metabolic function of intestinal flora.
Animals ; Acute Lung Injury/pathology* ; Lipopolysaccharides ; Ursidae ; Gastrointestinal Microbiome/drug effects* ; Bile/chemistry* ; Lipopolysaccharide Receptors/metabolism* ; Powders ; Male ; Lung/drug effects* ; Mice ; Peroxidase/metabolism* ; Signal Transduction/drug effects* ; Cytokines/metabolism*

OBJECTIVE: To evaluate the protective effects of resveratrol against acute lung injury (ALI) and investigate the potential mechanisms underlying the reactive oxygen species (ROS)-triggered thioredoxin-interacting protein (TXNIP)/NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) pathway. METHODS: C57BL/6 mice and J774A.1 cells were selected as the research subjects. Thirty Mice were randomly divided into 5 groups of 6 in each group: control with 0.9% saline, 5 mg/kg lipopolysaccharide (LPS) 24 h, 25 mg/kg resveratrol + 5 mg/kg LPS, 100 mg/kg resveratrol + 5 mg/kg LPS, and 4 mg/kg NLRP3 inhibitor CY-09 + 5 mg/kg LPS. For cell stimulation, cells were pretreated with 5 and 20 µmol/L resveratrol for 2 h, and stimulated with or without 1 µg/mL LPS and 3 mmol/L ATP for 2 h. The antioxidant N-acetyl-L-cysteine (NAC, 2 µmol/L) was used as the positive control group. Hematoxylin and eosin staining was used to evaluate the degree of lung LPS-induced tissue damage, and enzyme-linked immunosorbent assay was used to evaluate the contents of interleukin-1 β (IL-1 β) and IL-18 in the serum and cell supernatant. ROS and malondialdehyde (MDA) levels in the lung tissue were detected using the corresponding kits. Western blotting was used to detect the expressions of TXNIP, high-mobility group box 1 (HMGB1), NLRP3, as well as cysteine-aspartic acid protease 1 (caspase-1) and gasdermin D (GSDMD) along with their cleaved forms in lung tissue. Additionally, reverse transcription quantitative polymerase chain reaction was performed to analyze the expression of related inflammatory cytokines. ROS content was detected using flow cytometry and confocal laser microscopy. Mitochondrial morphological changes were observed using transmission electron microscopy, and HMGB1 expression was detected using immunofluorescence. RESULTS: Resveratrol significantly alleviated LPS-induced lung damage with reduced inflammation, interstitial edema, and leukocyte infiltration (P<0.01). It also decreased serum levels of IL-1 β and IL-18 (P<0.05), while downregulating the expressions of NLRP3, IL-6, and other inflammatory markers at both the protein and mRNA levels (P<0.05). Notably, the higher dose (100 mg/kg) demonstrated a better effect than the lower dose (25 mg/kg). In macrophages, resveratrol reduced IL-1 β and IL-18 following LPS and ATP stimulation, suppressed HMGB1 translocation, and inhibited formation and activation of the NLRP3 inflammasome (P<0.05 or P<0.01). These anti-inflammatory effects were mediated through the suppression ROS accumulation (P<0.01) and mitochondrial dysfunction. Transmission electron microscopy revealed that resveratrol preserved mitochondrial structure, preventing the mitochondrial damage seen in LPS-treated groups (P<0.01). The expressions of cleaved caspase-1, cleaved GSDMD, and cytoplasmic HMGB1 were all reduced following resveratrol treatment (P<0.01). Moreover, resveratrol inhibited dissociation of TXNIP from thioredoxin, blocking subsequent activation of NLRP3 and downstream inflammatory cytokines (P<0.01). Similarly, the higher concentration of resveratrol (20 µ mol/L) exhibited superior efficacy in vitro. CONCLUSION Resveratrol can reduce the inflammatory response following ALI and inhibit the activation of NLRP3 inflammasome and the level of HMGB1 in the cytoplasm by inhibiting ROS overproduction.
Acute Lung Injury/metabolism* ; NLR Family, Pyrin Domain-Containing 3 Protein/metabolism* ; Animals ; Resveratrol/pharmacology* ; Reactive Oxygen Species/metabolism* ; Inflammation/complications* ; Mice, Inbred C57BL ; Carrier Proteins/metabolism* ; Signal Transduction/drug effects* ; Lipopolysaccharides ; Thioredoxins/metabolism* ; Mice ; Lung/drug effects* ; Male ; Cell Line ; Interleukin-1beta/metabolism* ; Cell Cycle Proteins ; Stilbenes/therapeutic use*

OBJECTIVES: Acute lung injury (ALI) is an acute respiratory failure syndrome characterized by impaired gas exchange. Due to the lack of effective targeted drugs, it is associated with high mortality and poor prognosis. Tripterygium wilfordii (TW) has demonstrated anti-inflammatory activity in the treatment of various diseases. This study aims to investigate the effects and underlying mechanisms of TW on myeloid-derived suppressor cells (MDSCs) in ALI, providing experimental evidence for TW as a potential adjuvant therapy for ALI. METHODS: Eighteen specific pathogen-free (SPF) C57BL/6 mice were randomly divided into normal control (NC; intranasal saline), lipopolysaccharide (LPS; 5 mg/kg intranasally to induce ALI), and LPS+TW (50 mg/kg TW by gavage on the first day of modeling, followed by 5 mg/kg LPS intranasally to induce ALI) groups (n=6 each). Lung injury and edema were assessed by histopathological scoring and wet-to-dry weight ratio. Cytokine levels [interleukin (IL)-1β, IL-6, IL-18, tumor necrosis factor-α (TNF-α)] in lung tissue lavage fluid were measured by enzyme-linked immunosorbent assay (ELISA). Flow cytometry was used to assess the proportions of MDSCs, polymorphonuclear MDSCs (PMN-MDSCs), and monocytic MDSCs (M-MDSCs) in bone marrow, spleen, peripheral blood, and lung tissue, as well as reactive oxygen species (ROS) levels in lung tissues. Messenger RNA (mRNA) expression levels of inducible nitric oxide synthase (iNOS) and arginase-1 (ARG-1) in lung tissues were determined by real-time fluorescence quantitative polymerase chain reaction (RT-qPCR). PMN-MDSCs sorted from the lungs of LPS-treated mice were co-cultured with splenic CD3⁺ T cells and divided into NC, triptolide (TPL)-L, and TPL-H groups, with bovine serum albumin, 25 nmol/L TPL, and 50 nmol/L TPL, respectively. Flow cytometry was used to detect the effect of PMN-MDSCs on T-cell proliferation, and RT-qPCR was used to measure iNOS and ARG-1 mRNA expression. RESULTS: Compared with the NC group, the LPS group showed marked lung pathology with significantly increased histopathological scores and wet-to-dry ratios (both P<0.001). TW treatment significantly alleviated lung injury and reduced both indices compared with the LPS group (both P<0.05). Cytokine levels were significantly decreased in the LPS+TW group compared with the LPS group (all P<0.001). The proportions of MDSCs in CD45⁺ cells from spleen, bone marrow, peripheral blood, and lung, as well as PMN-MDSCs from spleen, peripheral blood, and lung, were significantly reduced in the LPS+TW group compared with the LPS group (all P<0.05), accompanied by reduced ROS levels in lung tissues (P<0.001). iNOS and ARG-1 mRNA expression in lung tissues was significantly lower in the LPS+TW group than in the LPS group (both P<0.001). In vitro, compared with the TPL-L group, the TPL-H group showed significantly increased CD3⁺ T-cell proliferation (P<0.001), and decreased iNOS and ARG-1 mRNA expression (all P<0.05). CONCLUSIONS TW alleviates the progression of LPS-induced ALI in mice, potentially by reducing the proportion of MDSCs in lung tissues and attenuating the immunosuppressive function of PMN-MDSCs.
Animals ; Acute Lung Injury/chemically induced* ; Myeloid-Derived Suppressor Cells/cytology* ; Tripterygium/chemistry* ; Mice, Inbred C57BL ; Mice ; Cell Differentiation/drug effects* ; Male ; Lipopolysaccharides ; Nitric Oxide Synthase Type II/genetics* ; Cytokines/metabolism* ; Reactive Oxygen Species/metabolism* ; Diterpenes/pharmacology* ; Epoxy Compounds ; Phenanthrenes

OBJECTIVES: Sepsis-associated acute lung injury (S-ALI) is one of the major causes of death in intensive care unit (ICU) patients, yet its mechanisms remain incompletely understood and effective therapies are lacking. Lytic cell death of macrophages is a key driver of the inflammatory cascade in S-ALI. PANoptosis, a newly recognized form of lytic cell death characterized by PANoptosome assembly and activation, involves plasma membrane rupture (PMR) mediated by ninjurin-1 (NINJ1), a recently identified pore-forming protein. Itaconic acid is known for its anti-inflammatory effects, but its role in macrophage PANoptosis during S-ALI is unclear. This study aims to investigate the protective effect of itaconic acid on macrophage PANoptosis in S-ALI to provide new therapeutic insights. METHODS: Male specific-pathogen-free C57BL/6J mice (6-8 weeks, 18-20 g) received intraperitoneal lipopolysaccharide (LPS) to establish a classical S-ALI model. Western blotting was used to assess PANoptosome-related proteins and enzymes involved in the itaconic acid metabolic pathway, while real-time reverse transcription polymerase chain reaction and metabolomics quantified itaconic acid levels. Primary peritoneal macrophages (PMs) were pretreated with the itaconate derivative 4-octyl itaconate (4-OI) and then exposed to tumor necrosis factor alpha (TNF-α) plus interferon gamma (IFN-γ) to induce PANoptosis. Cell viability was evaluated by cell counting kit-8 (CCK-8) assay. Western blotting was employed to quantify enzymes of the itaconate-metabolic pathway in PANoptotic macrophages, to evaluate the impact of 4-OI on PANoptosome-associated proteins, and to determine NINJ1 abundance in lung tissues from S-ALI mice and in PANoptotic macrophages. Fluorescent dye FM_4-64 was used to visualize 4-OI-mediated changes in PMR, whereas immunofluorescence staining mapped the effect of 4-OI on both the expression level and membrane localization of NINJ1 in PANoptotic macrophages. The effect of 4-OI on lactate dehydrogenase (LDH) release in culture supernatants and peripheal blood serum was assessed using a LDH assay kit, and non-denataring polyacylamide gel electrophoresis was used to assess the expression of NINJ1 in S-ALI mouse lung tissues and the impact of 4-OI on the expression of PANoptosis-associated NINJ1 multimeric reflected protein in macropahges. RESULTS: In S-ALI mouse lungs, PANoptosome components [NOD-like receptor thermal protein domain associated protein 3 (NLRP3), Gasdermin D (GSDMD), Caspase-1, Z-DNA binding protein (ZBP1), and Caspase-3] and phosphorylated mixed lineage kinase domain-like protein (MLKL) S345 were significantly upregulated (all P<0.05), while metabolomics showed compensatory increases in itaconic acid and its key enzymes [aconitate decarboxylase 1 (ACOD1)/immunoresponsive gene 1 (IRG1)]. In macrophages, 4-OI obviously suppressed PANoptosome protein expression, reduced LDH release, restored plasma membrane integrity, and inhibited NINJ1 expression and oligomerization at the membrane (P<0.05). CONCLUSIONS Itaconic acid may alleviate macrophage PANoptosis in S-ALI by inhibiting NINJ1-mediated plasma membrane rupture. Targeting NINJ1 or enhancing itaconate pathways may offer a novel therapeutic strategy for S-ALI.
Animals ; Acute Lung Injury/pathology* ; Succinates/pharmacology* ; Sepsis/complications* ; Mice, Inbred C57BL ; Male ; Mice ; Macrophages/pathology* ; Cell Membrane/metabolism* ; Lipopolysaccharides ; Hydro-Lyases

OBJECTIVES: To investigate the effect of amentoflavone (AF) for alleviating lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice and inhibiting NLRP3/ASC/Caspase-1 axis-mediated pyroptosis. METHODS: Female BALB/c mice were randomly divided into control group, LPS group, and AF treatment groups at low, moderate and high doses (n=12). ALI models were established by tracheal LPS instillation, and in AF treatment groups, AF was administered by gavage 30 min before LPS instillation. Six hours after LPS instillation, the mice were euthanized for examining lung tissue histopathological changes, protein levels in BALF, and MPO levels in the lung tissue. In the in vitro experiment, RAW264.7 cells were pretreated with AF, AC (a pyroptosis inhibitor), or their combination for 2 h before stimulation with LPS and ATP. The changes in cell proliferation and viability were detected using CCK-8 assay, and IL-1β, IL-6, IL-18, and TNF-α levels were determined with ELISA. Immunohistochemistry, immunofluorescence assay, and immunoblotting were used to detect the protein levels of NLRP3, ASC, cleaved caspase-1, and GSDMD N in rat lung tissues and the treated cells. RESULTS: In mice with LPS exposure, AF treatment significantly improved lung pathologies and edema, reduced protein levels in BALF and pulmonary MPO level, inhibited the high expression of NLRP3/ASC/Aspase-1 axis, reduced the expression of GSDMD N, and lowered the release of IL-1β, IL-6, IL-18, and TNF‑α. In RAW264.7 cells with LPS and ATP stimulation, AF pretreatment effectively reduced cell death, inhibited activation of the NLRP3/ASC/Aspase-1 axis, and reduced GSDMD N expression and the inflammatory factors. The pyroptosis inhibitor showed a similar effect to AF, and their combination produced more pronounced effects in RAW264.7 cells. CONCLUSIONS Amentoflavone can alleviate ALI in mice possibly by inhibiting NLRP3/ASC/Caspase-1 axis-mediated cell pyroptosis.
Animals ; Pyroptosis/drug effects* ; Acute Lung Injury/pathology* ; Mice ; Mice, Inbred BALB C ; Female ; Lipopolysaccharides ; Biflavonoids/pharmacology* ; RAW 264.7 Cells ; NLR Family, Pyrin Domain-Containing 3 Protein ; Caspase 1/metabolism* ; Lung

OBJECTIVES: To compare the anti-inflammatory, antibacterial and analgesic effects of Yinqiao Powder (YQS) formulated granules and decoction. METHODS: We first evaluated the anti-inflammatory effects of the two dosage forms of YQS in a LPS-induced RAW 264.7 cell model using RT-qPCR and Western blotting. We further constructed zebrafish models of inflammation by copper sulfate exposure, caudal fin transection, or LPS and Poly (I:C) microinjection, and evaluated anti-inflammatory effects of YQS granules and decoction by examining neutrophil aggregation and HE staining findings. In a mouse model of acute lung injury (ALI) induced by intratracheal LPS instillation, the effects of YQS gavage at 10, 15, and 20 g/kg on lung pathologies were evaluated by calculating lung wet-dry weight ratio and using HE staining, ELISA and Western blotting. The microbroth dilution method was used to evaluate the antibacterial effect of YQS. Mouse pain models established by hot plate and intraperitoneal injection of glacial acetic acid were used to evaluate the analgesic effects of YQS at 10, 15, and 20 g/kg. RESULTS: Both YQS granules and decoction significantly reduced TNF-α, IL-6, and IL-1β expressions and p-STAT3 (Tyr 705) phosphorylation level in LPS-induced RAW 264.7 cells, and obviously inhibited neutrophil aggregation in the zebrafish models. In ALI mice, YQS granules and decoction effectively ameliorated lung injury, lowered lung wet-dry weight ratio, and reduced p-STAT3 (Tyr 705) expression and TNF-α and IL-6 levels. YQS produced obvious antibacterial effect at the doses of 15.63 and 31.25 mg/mL, and significantly reduced body torsion and increased pain threshold in the mouse pain models. CONCLUSIONS The two dosage forms of TQS have similar anti-inflammatory, antibacterial and analgesic effects with only differences in their inhibitory effect on TNF-α, IL-6 and IL-1β mRNA expressions in LPS-induced RAW 264.7 cells.
Animals ; Mice ; Drugs, Chinese Herbal/pharmacology* ; Anti-Inflammatory Agents/pharmacology* ; Analgesics/pharmacology* ; RAW 264.7 Cells ; Zebrafish ; Anti-Bacterial Agents/pharmacology* ; Powders ; Tumor Necrosis Factor-alpha/metabolism* ; Acute Lung Injury/drug therapy* ; Interleukin-6/metabolism* ; Lipopolysaccharides

OBJECTIVES: To develop an E-selectin-targeting nanomedicine delivery system that competitively inhibits E-selectin-neutrophil ligand binding to block neutrophil adhesion to vessels and suppress their recruitment to the lesion sites. METHODS: Doxorubicin hydrochloride (DOX)-loaded liposomes (IEL-Lip/DOX) conjugated with E-selectin-affinity peptide IELLQARC were developed using a post-insertion method. Two formulations [2-1P: Mol(PC): Mol(DPI)=100:1; 2-3P: 100:3] were prepared and their modification density and in vitro release characteristics were determined. Their targeting efficacy was assessed in a cell model of LPS-induced inflammation, a mouse model of acute lung injury (ALI), a rat femoral artery model of physical injury-induced inflammation, and a zebrafish model of local inflammation. RESULTS: The prepared IEL-Lip/DOX 2-1P and 2-3P had peptide modification densities of 4.76 and 7.57 pmoL/cm², respectively. Compared with unmodified liposomes, IEL-Lip/DOX exhibited significantly reduced 48-h cumulative release rates at pH 5.5. In the inflammation cell model, IEL-Lip/DOX showed increased uptake by activated inflammatory endothelial cells, and 2-1P exhibited a higher trans-endothelial ability. In ALI mice, the fluorescence intensity of IEL-Lip/Cy5.5 increased significantly in lung tissues by 53.71% [Z-(2-1P)] and 93.41% [Z-(2-3P)], and 2-1P had an increased distribution by 24.19% in the inflammatory lung tissue compared to normal mouse lung tissue. In rat femoral artery models, 2-1P had greater injured/normal vessel fluorescence intensity contrast. In the zebrafish models, both 2-1P and 2-3P showed increased aggregation at the site of inflammation. CONCLUSIONS This E-selectin-targeting nanomedicine delivery system efficiently targets activated inflammatory endothelial cells to increase drug concentration at the inflammatory site, which sheds light on new strategies for treating neutrophil-mediated inflammatory diseases and practicing the concept of "one drug for multiple diseases".
Animals ; Liposomes ; Rats ; Nanomedicine ; E-Selectin ; Drug Delivery Systems ; Inflammation/drug therapy* ; Mice ; Doxorubicin/analogs & derivatives* ; Zebrafish ; Acute Lung Injury/drug therapy*

Since the beginning of the 21st century, the severe respiratory infectious diseases worldwide [such as severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), influenza A H1N1 and novel coronavirus infection have attracted wide attention from all walks of life due to their superior pathogenicity and transmissibility. Aerosols-carrying pathogens are the main transmission route of many severe respiratory infectious diseases, which can lead to severe respiratory failure and even acute respiratory distress syndrome (ARDS) in infected individuals. Mechanical ventilation is the primary treatment for ARDS, and the small tidal volume, appropriate level of positive end-expiratory pressure based lung protective ventilation strategy can effectively reduce the incidence of ventilator-induced lung injury (VILI). However, in the process of clinical treatment, it is sometimes necessary to briefly disconnect the connection between the artificial airway and the ventilator circuit, which will not only cause the residual aerosol in the respiratory system to spill out and pollute the surrounding environment, increase the risk of nosocomial infection including medical staff, but also interfere with the implementation of lung protective ventilation strategy and aggravate ventilator-induced lung injury. In addition, studies have shown that a lot of medical staff have nosocomial infections, especially staff involved in tracheal intubation, extubation and other airway related operations. In addition to enhancing personal protective measures, it is crucial to safeguard healthcare workers from aerosol contamination and minimize associated risks during airway management. At present, there are few researches on the temporary sealing of airway lines and ventilator system, and there is a lack of clear guidance. This review summarizes the research status in related fields to provide a reference for corresponding solutions and programs.
Humans ; Respiratory Distress Syndrome/etiology* ; Respiration, Artificial ; Ventilator-Induced Lung Injury/prevention & control* ; Severe Acute Respiratory Syndrome ; COVID-19 ; Clinical Relevance

OBJECTIVE: To investigate whether the G protein-coupled estrogen receptor (GPER) can attenuates acute lung injury in mice with exertional heat stroke (EHS) by inhibiting ferroptosis. METHODS: Sixty SPF-grade male C57BL/6 mice were randomly divided into four groups: normal control group (control group), EHS model group (EHS group), dimethyl sulfoxide (DMSO) solvent group (EHS+DMSO group), and GPER-specific agonist G1 group (EHS+G1 group), with 15 mice in each group. All mice underwent 14 days of adaptive training at 24-26 centigrade before modeling, and the EHS model was established using a high-temperature treadmill device. After successful modeling, the mice were allowed to cool naturally at room temperature. In the EHS+G1 group, 40 μg/kg of the GPER-specific agonist G1 was slowly injected intraperitoneally immediately after modeling. In the EHS+DMSO group, 40 μg/kg of DMSO was slowly injected intraperitoneally immediately after modeling. The control group received no treatment. Five hours after modeling, abdominal aortic blood was collected, and lung tissues were harvested after euthanasia. The lung coefficient was calculated to evaluate lung injury. Lung histopathological changes were observed under a light microscope after hematoxylin-eosin (HE) staining, and a lung histopathological score was assigned. Enzyme-linked immunosorbent assay (ELISA) was used to detect serum levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), malondialdehyde (MDA), and Fe²⁺ in lung tissue. Immunofluorescence was used to detect the expression of glutathione peroxidase 4 (GPX4). Real-time polymerase chain reaction (RT-PCR) was used to detect the mRNA expression of GPX4, ferroportin 1 (FPN1), and ferritin heavy chain 1 (FTH1). Western blotting was performed to detect the protein expression of GPX4, FPN1, and FTH1. RESULTS: Compared with the control group, the lung coefficient and lung histopathological score were significantly increased in the EHS group. HE staining showed significant thickening and unevenness of the alveolar septa and alveolar walls, partial alveolar collapse, and extensive erythrocyte, inflammatory cell, and plasma-like material extravasation in the alveolar spaces. Serum levels of TNF-α, IL-1β, MDA, and Fe²⁺ were significantly elevated. Immunofluorescence staining showed a significant decrease in GPX4-positive expression in lung tissue. Western blotting and RT-PCR showed significantly reduced protein and mRNA expression of GPX4, FPN1, and FTH1 in lung tissue. Compared with the EHS group, the EHS+G1 group showed a significant reduction in lung coefficient and lung histopathological score [lung coefficient (mg/g): 3.9±0.1 vs. 4.6±0.3, lung histopathological score: 4.2±0.2 vs. 6.9±0.2, both P < 0.05]. HE staining revealed reduced severity of lung tissue fluid extravasation, inflammatory infiltration, decreased hemorrhage, and less severe alveolar structural damage. Serum levels of TNF-α, IL-1β, MDA, and Fe²⁺ were significantly reduced [TNF-α (ng/L): 44.3±0.2 vs. 64.6±0.3, IL-1β (ng/L): 69.3±0.4 vs. 97.8±0.2, MDA (nmol/L): 2.8±0.3 vs. 3.6±0.5, Fe²⁺ (nmol/L): 0.021±0.004 vs. 0.028±0.004, all P < 0.05]. Immunofluorescence staining showed a significant decrease in GPX4-positive expression in lung tissue (fluorescence intensity: 35.53±2.41 vs. 16.45±0.31, P < 0.05). RT-PCR and Western blotting showed significantly increased mRNA and protein expression of GPX4, FPN1, and FTH1 in lung tissue [mRNA expression: GPX4 mRNA (2^-ΔΔCt): 0.44±0.05 vs. 0.09±0.01, FPN1 mRNA (2^-ΔΔCt): 0.77±0.17 vs. 0.42±0.14, FTH1 mRNA (2^-ΔΔCt): 0.75±0.04 vs. 0.58±0.01; protein expression: GPX4/β-actin: 0.96±0.11 vs. 0.24±0.04, FPN1/β-actin: 1.26±0.21 vs. 0.44±0.14, FTH1/β-actin: 0.27±0.12 vs. 0.15±0.07; all P < 0.05]. However, there were no statistically significant differences in any of the above indicators between the EHS+DMSO group and the EHS group. CONCLUSION Activation of GPER can attenuate EHS-related lung injury in mice, and its mechanism may be related to the activation of the GPX4 signaling pathway and inhibition of ferroptosis.
Animals ; Mice, Inbred C57BL ; Male ; Mice ; Heat Stroke/metabolism* ; Receptors, G-Protein-Coupled ; Ferroptosis ; Receptors, Estrogen ; Acute Lung Injury/metabolism* ; Tumor Necrosis Factor-alpha/metabolism* ; Interleukin-1beta/metabolism* ; Lung Injury ; Lung/metabolism*

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) is a severe critical condition marked by rapid progression and high fatality. It results from direct/indirect lung-related or systemic triggers, leading to widespread injury of lung epithelial and endothelial cells. Its pathogenesis involves uncontrolled inflammation and breakdown of the lung's blood-air barrier due to leaky blood vessels and epithelial damage. Current management of ALI/ARDS remains primarily supportive, offering symptomatic relief but limited improvement in prognosis, necessitating deeper exploration of upstream pathogenic mechanisms to identify safer and more effective therapies. Exosomal microRNAs (miRNA), small extracellular vesicles (40-150 nm) containing non-coding single-stranded RNAs, regulate post-transcriptional cellular processes and participate in ALI/ARDS pathophysiology. Studies reveal that exosomes transport proteins, nucleic acids, and miRNAs to recipient cells, mediating intercellular communication. In ALI/ARDS models, exosomal miRNAs delivered to alveolar epithelial cells, endothelial cells, macrophages, and neutrophils critically modulate autophagy, pyroptosis, apoptosis, proliferation, inflammatory signaling, macrophage polarization, and neutrophil activation, either exacerbating or alleviating disease progression. Recent advances in engineering techniques have enhanced the therapeutic potential of exosomal miRNAs by overcoming limitations of natural exosomes. This review focuses on exosomal miRNA-mediated regulation of ALI/ARDS pathogenesis across key cell types, providing insights for novel therapeutic strategies.
Exosomes ; Humans ; MicroRNAs ; Acute Lung Injury ; Respiratory Distress Syndrome ; Animals