Pulmonary Innate Immune Response Determines the Outcome of Inflammation During Pneumonia and Sepsis-Associated Acute Lung Injury

Shufeng Jiedu capsule inhibits inflammation and apoptosis by activating A2AAR and inhibiting NF-κB to alleviate LPS-induced ALI

ETHNOPHARMACOLOGICAL RELEVANCE

Shufeng Jiedu capsule (SFJDC) is a pure form of traditional Chinese medicine (TCM) that contains eight medicinal plants. Known for its anti-inflammatory and antipyretic effects, it is mostly used to treat upper respiratory tract infections and other infectious diseases, such as colds, pharyngitis, laryngitis, and tonsillitis. Both acute lung injury (ALI) and COVID-19 are closely related to lung damage, primarily manifesting as lung inflammation and epithelial cell damage. However, whether SFJDC can improve ALI and by what mechanism remain unclear. The purpose of this study was to explore whether SFJDC could be used as a prophylactic treatment for COVID-19 by improving acute lung injury.

AIM OF THE STUDY

The purpose of this study was to determine whether SFJDC could protect against ALI caused by lipopolysaccharide (LPS), and we wanted to determine how SFJDC reduces inflammation and apoptosis pharmacologically and molecularly.

MATERIALS AND METHODS

Preadministering SFJDC at 0.1 g/kg, 0.3 g/kg, or 0.5 g/kg for one week was followed by 5 mg/kg LPS to induce ALI in mice. Observations included the study of lung histomorphology, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) secretion, as well as the ratio of lung wet/dry weights. In addition, RAW264.7 cells were treated for 24 h with 1 μg/mL LPS after being pretreated for 1 h with 0.5 mg/mL SFJDC. In the samples, we detected TNF-α, IL-1β, and IL-6. Cell apoptosis was detected by stimulating A549 cells for 24 h with RAW264.7 supernatant. Both in vitro and in vivo, the levels of A2A adenosine receptor (A2AAR), PKA, IκB, p-IκB, NF-κB P65 (P65), p-NF-κB P65 (p-P65), cleaved caspases-3 (Cc3), Bcl-2 associated X protein (Bax), and B-cell lymphoma-2 (Bcl-2) proteins were determined using Western blot analysis.

RESULTS

Lung tissue morphology was improved as SFJDC decreased cytokine secretion, the ratio of lung wet/dry weights, and lung tissue secretion of proinflammatory cytokines. The expression of A2AAR was increased by SFJDC, and the phosphorylation of NF-κB was inhibited. TUNEL staining and flow cytometry showed that SFJDC inhibited apoptosis by reducing the expression of Cc3 and the ratio of Bax/Bcl-2.

CONCLUSIONS

According to the results of this study, SFJDC can reduce inflammation and inhibit apoptosis. A2AAR activation and regulation of NF-κB expression are thought to make SFJDC anti-inflammatory and anti-apoptotic. A wide range of active ingredients may result in an anti-inflammatory and antipyretic effect with SFJDC.

Molecular mechanisms and roles of pyroptosis in acute lung injury

ABSTRACT

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), which are characterized by excessive inflammation and accompanied by diffuse injury of alveoli, can result in severe respiratory failures. The morbidity and mortality of patients remain high because the major treatments for ALI/ARDS are mainly supportive due to the lack of effective therapies. Numerous studies have demonstrated that the aggravation of coronavirus disease 2019 (COVID-19) leads to severe pneumonia and even ARDS. Pyroptosis, a biological process identified as a type of programed cell death, is mainly triggered by inflammatory caspase activation and is directly meditated by the gasdermin protein family, as well as being associated with the secretion and release of pro-inflammatory cytokines. Clinical and experimental evidence corroborates that pyroptosis of various cells in the lung, such as immune cells and structural cells, may play an important role in the pathogenesis of "cytokine storms" in ALI/ARDS, including those induced by COVID-19. Here, with a focus on ALI/ARDS and COVID-19, we summarized the recent advances in this field and proposed the theory of an inflammatory cascade in pyroptosis to identify new targets and pave the way for new approaches to treat these diseases.

SRPK1 promotes sepsis-induced acute lung injury via regulating PI3K/AKT/FOXO3 signaling

OBJECTIVE

Sepsis is the most common cause of death in intensive care unit. Moreover, sepsis is the leading cause of acute lung injury (ALI). Serine-arginine protein kinase 1 (SRPK1) was demonstrated to promote the development of ALI. However, the potentials of SRPK1 in sepsis-induced ALI are still unknown. This study aimed to investigate the potentials of SRPK1 in sepsis-induced ALI and the underlying mechanisms.

METHODS

Cecal ligation and puncture (CLP) was performed to establish sepsis-induced ALI model in vivo. Primary human pulmonary microvascular endothelial cells (HPMECs) were exposed to lipopolysaccharide (LPS) to construct sepsis-induced ALI model in vitro. Gene expression was detected using western blot and qRT-PCR. The interaction between forkhead box O3 (FOXO3) and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) was detected using luciferase and Chromatin immunoprecipitation (ChIP) assay. Cellular functions were CCK-8, colony formation, PI staining, and flow cytometry assay.

RESULTS

SRPK1 was downregulated in patients with sepsis-induced ALI. Overexpression of SRPK1 suppressed the pyroptosis of HPMECs as well as promoted cell proliferation. Additionally, SRPK1 overexpression alleviated sepsis-induced ALI in vivo. SRPK1 activated phosphatidylinositol3-kinase (PI3K) signaling pathways. Blocking the activation of PI3K degraded the cellular functions of HPMECs. Moreover, FOXO3 transcriptionally inactivated NLRP3 and suppressed its mRNA and protein expression.

CONCLUSION

Taken together, SRPK1 suppressed sepsis-induced ALI via regulating PI3K/AKT/FOXO3/NLRP3 signaling. SRPK1 may be the potential biomarker for sepsis-induced ALI.

Transcriptome profiling of lung immune responses potentially related to acute respiratory distress syndrome in forest musk deer

Background

Forest musk deer is an endangered species globally. The death of captive forest musk deer can be caused by certain respiratory system diseases. Acute respiratory distress syndrome (ARDS) is a huge threat to the life of forest muck deer that breed in our department.

Methods

Lung histopathologic analysis was conducted by hematoxylin and eosin (HE) staining. The lung gene changes triggered by ARDS were examined by RNA sequencing and related bioinformatics analysis in forest musk deer. The potential functions of unigenes were investigated by NR, SwissProt KOG, GO, and KEGG annotation analyses. Vital biological processes or pathways in ARDS were examined by GO and KEGG enrichment analyses.

Results

A total of 3265 unigenes were differentially expressed (|log₂fold-change|> 2 and adjusted P value < 0.01) in lung tissues of 3 forest musk deer with ARDS compared with normal lung tissues of the non-ARDS group. These differentially expressed unigenes (DEGs) played crucial roles in immunity and defense responses to pathogens. Moreover, we identified the DEGs related to one or more of the following biological processes: lung development, immunity, and bacterial/viral/fungal infection. And six DEGs that might be involved in lung injury caused by immune dysregulation or viral/fungal infection were identified.

Conclusion

ARDS-mediated lung gene alterations were identified in forest musk deer. Moreover, multiple genes involved in lung development and lung defense responses to bacteria/viruses/fungi in ARDS were filtered out in forest musk deer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08917-7.

Focus on long non-coding RNA MALAT1: Insights into acute and chronic lung diseases

Acute lung injury (ALI) is a pulmonary illness with a high burden of morbidity and mortality around the world. Chronic lung diseases also represent life-threatening situations. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is a type of long non-coding RNA (lncRNA) and is highly abundant in lung tissues. MALAT1 can function as a competitive endogenous RNA (ceRNA) to impair the microRNA (miRNA) inhibition on targeted messenger RNAs (mRNAs). In this review, we summarized that MALAT1 mainly participates in pulmonary cell biology and lung inflammation. Therefore, MALAT1 can positively or negatively regulate ALI and chronic lung diseases (e.g., chronic obstructive pulmonary disease (COPD), bronchopulmonary dysplasia (BPD), pulmonary fibrosis, asthma, and pulmonary hypertension (PH)). Besides, we also found a MALAT1-miRNA-mRNA ceRNA regulatory network in acute and chronic lung diseases. Through this review, we hope to cast light on the regulatory mechanisms of MALAT1 in ALI and chronic lung disease and provide a promising approach for lung disease treatment.

The traditional Chinese patented medicine Qingke Pingchuan granules alleviates acute lung injury by regenerating club cells

Qingke Pingchuan granules (QKPCG), a patented traditional Chinese medicine, clinically, are recommended for acute tracheobronchitis, cough, community‐acquired pneumonia, and other respiratory diseases. However, its potential protective effect and mechanism of action in acute lung injury (ALI) have not been explored. We aimed to explore the mechanisms underlying the protective role of QKPCG in ALI. The therapeutic efficacy of QKPCG was investigated in a lipopolysaccharide (LPS)‐induced ALI mouse model. Mice were divided into three groups, namely, the Control, LPS, and LPS + QKPCG groups. Mice in the LPS + QKPCG group were administered QKPCG intragastrically as a treatment once a day for a total of three days. QKPCG effectively increased survival and reduced lung injury in treated mice. It significantly reduced the LPS‐induced expression of interleukin (IL)‐6, tumor necrosis factor‐α (TNF‐α), IL‐1α, and IL‐1β. RNA‐sequencing followed by real‐time quantitative polymerase chain reaction validation suggested a critical role of the secretoglobin family 1A member 1 (Scgb1a1) gene in mediating the protective effect of QKPCG. Further, QKPCG reversed the LPS‐induced downregulation of the Clara cell 10 kDa protein (CC10), a pulmonary surfactant protein encoded by Scgb1a1, which is mainly secreted by club cells in the lungs. Exogenous supplementation of CC10 alleviated LPS‐induced ALI. Hematoxylin and eosin staining and enzyme‐linked immunosorbent assay results further confirmed the anti‐inflammatory properties of CC10, which were suggested as mediated via the inhibition of NFκB phosphorylation. In summary, our study provides evidence of the beneficial role of QKPCG in alleviating lung injury, mediated via the decreased disruption of club cells and higher expression of CC10, which leads to NFκB pathway inhibition.

Deciphering the role of damage-associated molecular patterns and inflammatory responses in acute lung injury

Acute lung injury (ALI) is characterized by diffuse pulmonary infiltrates and causes great mortality. ALI presents with overproduction of proinflammatory cytokines, cell death, destruction of alveoli-endothelial barriers, and neutrophil infiltration in lung tissues. Damage-associated molecular patterns (DAMPs) are molecules released from damaged cells due to infection, trauma, etc. DAMPs activate innate and adaptive immunity, trigger inflammatory responses, and are important in the initiation and development of ALI. We reviewed the literatures on DAMPs in ALI. Alveolar macrophages (AMs), neutrophils, and epithelial cells (AECs) are important in the pathogenesis of ALI. We comprehensively analyzed the interaction between DAMPs and AMs, alveolar neutrophils, and AECs. During the initial stage of ALI, ruptured cell membranes or destroyed mitochondria release DAMPs. DAMPs activate the inflammasome in nearby sentinel immune cells, such as AMs. AMs produce IL-1β and other cytokines. These mediators upregulate adhesion molecules of the capillary endothelium that facilitate neutrophil recruitment. The recruited neutrophils detect DAMPs using formyl peptide receptors on the membrane, guiding their migration to the injured site. The accumulation of immune cells, cytokines, chemokines, proteases, etc., results in diffuse alveolar damage and pulmonary hyperpermeability with protein-rich fluid retention. Some clinical studies have shown that patients with ALI with higher circulating DAMPs have higher mortality rates. In conclusion, DAMPs are important in the initiation and progression of ALI. The interactions between DAMPs and AMs, neutrophils, and AECs are important in ALI. This review comprehensively addresses the mechanisms of DAMPs and their interactions in ALI.

Extracellular Vesicles Derived from Mesenchymal Stem Cells: A Potential Biodrug for Acute Respiratory Distress Syndrome Treatment

Acute respiratory distress syndrome (ARDS) is a severe respiratory disease associated with high morbidity and mortality in the clinic. In the face of limited treatment options for ARDS, extracellular vesicles derived from mesenchymal stem cells (MSC-EVs) have recently shown promise. They regulate levels of growth factors, cytokines, and other internal therapeutic molecules. The possible therapeutic mechanisms of MSC-EVs include anti-inflammatory, cell injury repair, alveolar fluid clearance, and microbe clearance. The potent therapeutic ability and biocompatibility of MSC-EVs have enabled them as an alternative option to ameliorate ARDS. In this review, recent advances, therapeutic mechanisms, advantages and limitations, as well as improvements of using MSC-EVs to treat ARDS are summarized. This review is expected to provide a brief view of the potential applications of MSC-EVs as novel biodrugs to treat ARDS.

XueFu ZhuYu Decoction Alleviates Cardiopulmonary Bypass-Induced NLRP3 Inflammasome-Dependent Pyroptosis by Inhibiting IkB-α/NF-κB Pathway in Acute Lung Injury Rats

XueFu ZhuYu Decoction (XFZYD) is an effective prescription that is widely used to improve blood circulation by removing blood stasis. This study aimed to investigate the effects and the underlying molecular mechanisms of XFZYD on lung pyroptosis in cardiopulmonary bypass- (CPB-) induced acute lung injury (ALI) rats. A rat model of ALI was induced by CPB treatment after XFZYD, Ac-YVAD-CMK, and Bay-11-7082 administration. The respiratory index (RI) and oxygenation index (OI) were determined at each time point. The levels of interleukin (IL)-1β, IL-6, IL-18, and TNF-α in serum and lung were measured by enzyme-linked immunosorbent assays (ELISA). Moreover, the protein levels, neutrophil counts, and total cell of bronchoalveolar lavage fluid (BALF) were detected. Additionally, Myeloperoxidase (MPO) expression was detected by immunohistochemical assay. Lung injury was evaluated with the wet/dry (W/D) ratio and pathologic changes, respectively. Besides, the expression of NLRP3 inflammasome and IkB-α/NF-κB pathway proteins was estimated by immunofluorescence, quantitative real-time PCR (qRT-PCR), and Western blotting assays, respectively. XFZYD pretreatment significantly ameliorated pulmonary ventilation function and reduced the CPB-induced lung histopathological injury, inflammatory cell infiltration in BALF and lung, and the apoptosis of lung cells. Interestingly, XFZYD decreased the CPB-induced NLRP3, ASC, Caspase-1 p20, Pro-GSDMD, GSDMD p30, IL-18, IL-1β p-P65, and p-IKBα mRNA or protein levels in lung tissues in ALI model rats. In summary, these findings suggest that XFZYD effectively mitigates NLRP3 inflammasome-dependent pyroptosis in CPB-induced ALI model rats, possibly by inhibiting the IkB-α/NF-κB pathway in the lung.

Deoxyelephantopin alleviates lipopolysaccharide-induced septic lung injury through inhibiting NF-ĸB/STAT3 axis

Sepsis induces multiple organ dysfunction syndromes, such as acute kidney, liver, or lung injury. Septic lung injury is associated with excessive apoptosis and inflammatory responses in hepatocytes. Deoxyelephantopin is a sesquiterpene lactone found in Elephantopus scaber L, and has immunomodulatory, antibacterial, anti-inflammatory, and antifungal properties. The role of deoxyelephantopin in sepsis-associated lung injury was investigated. First, human bronchial epithelial cells (BEAS-2B) and human pulmonary artery endothelial cells (HPAEC) were treated with lipopolysaccharide to induce cytotoxicity. Treatment with lipopolysaccharide reduced cell viability of BEAS-2B and HPAEC, and promoted cell apoptosis through down-regulation of poly (ADP-ribose) polymerase (PARP) and B-cell lymphoma 2 (Bcl-2), and up-regulation of cleaved PARP and B-cell lymphoma-associated X protein (Bax). Second, lipopolysaccharide-treated BEAS-2B and HPAEC were incubated with increasing concentrations of deoxyelephantopin, that is, 1, 5, or 10 μM. Deoxyelephantopin enhanced cell viability and reduced cell apoptosis of lipopolysaccharide-treated BEAS-2B and HPAEC. Third, deoxyelephantopin attenuated lipopolysaccharide-induced decrease of superoxide dismutase and glutathione, and increase of malondialdehyde and myeloperoxidase in BEAS-2B and HPAEC. Moreover, deoxyelephantopin also weakened lipopolysaccharide-induced increase of tumor necrosis factor-α, interleukin (IL)-1β, and IL-6. Finally, deoxyelephantopin decreased protein expression of p-p65 and p-signal transducer and activator of transcription 3 (STAT3) in lipopolysaccharide-treated BEAS-2B and HPAEC. In conclusion, deoxyelephantopin exhibited anti-oxidative and anti-inflammatory effects against lipopolysaccharide-treated BEAS-2B and HPAEC through inactivation of nuclear factor kappa B/STAT3 signaling.

Targeting circNCLN/miR-291a-3p/TSLP signaling axis alleviates lipopolysaccharide-induced acute lung injury

Acute lung injury (ALI) is a life-threatening disease caused by the severe and acute response of the lungs to a variety of direct and indirect insults. Patients with ALI are currently treated mainly with respiratory support due to inadequate understanding of ALI progression. Alveolar epithelial cells produced thymic stromal lymphopoietin (TSLP) has been proved to worsen ALI by triggering airway inflammation. However, the regulation mechanism of TSLP expression remains unclear. In this study, we identified the crucial role played by circNCLN in lipopolysaccharide (LPS)-induced ALI. We demonstrated for the first time that miR-291a-3p could directly bind to the 3'UTR of TSLP and suppress TSLP expression in alveolar epithelial cells. Mechanistically, our data identified that circNCLN acts as a molecular sponge to antagonize miR-291a-3p and thereby maintaining the expression of TSLP in alveolar epithelial cells. Importantly, targeting circNCLN by its antisense oligonucleotide (ASO) markedly alleviated LPS-induced ALI. Therefore, our results suggested that circNCLN/miR-291a-3p/TSLP axis may be an important signaling in LPS-induced ALI and circNCLN inhibition may serve as a potential treatment of ALI.

Oxypeucedanin relieves LPS-induced acute lung injury by inhibiting the inflammation and maintaining the integrity of the lung air-blood barrier

Introduction: Acute lung injury (ALI) is commonly accompanied by a severe inflammatory reaction process, and effectively managing inflammatory reactions is an important therapeutic approach for alleviating ALI. Macrophages play an important role in the inflammatory response, and this role is proinflammatory in the early stages of inflammation and anti-inflammatory in the late stages. Oxypeucedanin is a natural product with a wide range of pharmacological functions. This study aimed to determine the effect of oxypeucedanin on lipopolysaccharide (LPS)-induced ALI.

Methods and Results: In this study, the following experiments were performed based on LPS-induced models in vivo and in vitro. Using myeloperoxidase activity measurement, ELISA, qRT-PCR, and Western blotting, we found that oxypeucedanin modulated the activity of myeloperoxidase and decreased the expression levels of inflammatory mediators such as TNF-α, IL-6, IL-1β, MPO, COX-2 and iNOS in LPS-induced inflammation models. Meanwhile, oxypeucedanin inhibited the activation of PI3K/AKT and its downstream NF-κB and MAPK signaling pathways. In addition, oxypeucedanin significantly decreased the pulmonary vascular permeability, which was induced by LPSs, and the enhanced expression of tight junction proteins (Occludin and Claudin 3).

Conclusions: In conclusion, this study demonstrated that the anti-inflammatory mechanism of oxypeucedanin is associated with the inhibition of the activation of PI3K/AKT/NF-κB and MAPK signaling pathways and the maintenance of the integrity of the lung air-blood barrier.

Antioxidant mitoquinone ameliorates EtOH-LPS induced lung injury by inhibiting mitophagy and NLRP3 inflammasome activation

Chronic ethanol abuse is a systemic disorder and a risk factor for acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD). However, the mechanisms involved are unknown. One explanation is that ethanol produces damaging reactive oxygen species (ROS) and disturbs the balance of mitochondria within the lungs to promote a pro-injury environment. We hypothesized that targeting an antioxidant to the mitochondria would prevent oxidative damage and attenuate EtOH-LPS-induced lung injury. To test this, we investigated the effects of mitochondria-targeted ubiquinone, Mitoquinone (MitoQ) on ethanol-sensitized lung injury induced by LPS. Lung inflammation, ROS, mitochondria function, and mitophagy were assessed. We demonstrated that chronic ethanol feeding sensitized the lung to LPS-induced lung injury with significantly increased reactive oxygen species ROS level and mitochondrial injury as well as lung cellular NLRP3 inflammasome activation. These deleterious effects were attenuated by MitoQ administration in mice. The protective effects of MitoQ are associated with decreased cellular mitophagy and NLRP3 inflammasome activation in vivo and in vitro. Taken together, our results demonstrated that ethanol aggravated LPS-induced lung injury, and antioxidant MitoQ protects from EtOH-LPS-induced lung injury, probably through reducing mitophagy and protecting mitochondria, followed by NLRP3 inflammasome activation. These results will provide the prevention and treatment of ethanol intake effects with new ideas.

Pinelliae rhizoma alleviated acute lung injury induced by lipopolysaccharide via suppressing endoplasmic reticulum stress-mediated NLRP3 inflammasome

Pinelliae rhizoma (PR), one kind of commonly-used Chinese herbs, is generally prescribed to treat various respiratory diseases, including acute lung injury (ALI). However, the accurate bioactive ingredients of PR and the underlying pharmacological mechanism have both not been fully elucidated. Therefore, this study aimed to identify the bioactive ingredients that could alleviate lipopolysaccharide (LPS)-induced ALI and explore the possible mechanism involved. Our results confirmed that LPS infection indeed caused acute inflammatory damage in mice lung, accompanying with the enhancement of IL-1β contents and the activation of the NLRP3 inflammasome in lung tissue and macrophagocyte, all of which were remarkably ameliorated by PR treatment. Next, mechanistically, LPS was found to trigger endoplasmic reticulum (ER) stress and downstream cellular calcium ions (Ca²⁺) release via activating Bip/ATF4/CHOP signaling pathway. Like PR, 4-PBA (a specific inhibitor of ER stress) not only obviously reversed Bip/ATF4/CHOP-mediated ER stress, but also significantly attenuated LPS-induced activation of the NLRP3 inflammasome. Furthermore, the bioactive ingredients of PR, which generated the anti-inflammatory effects, were screened by metabolomics and network pharmacology. In vitro experiments showed that chrysin, dihydrocapsaicin, and 7,8-dihydroxyflavone (7,8-DHF) notably suppressed LPS-induced ER stress and following NLRP3 inflammasome activation. In conclusion, our findings suggested that PR alleviated LPS-induced ALI by inhibiting ER stress-mediated NLRP3 inflammasome activation, which is mainly relevant with these three bioactive ingredients. This study provided a theoretical basis for the clinical application of PR to treat ALI, and these bioactive ingredients of PR would be promising therapeutic drugs for the treatment of ALI.

Identification of the key ferroptosis-related genes involved in sepsis progression and experimental validation in vivo

Background: Ferroptosis has a vital role in sepsis, but the mechanism is not known. Understanding the mechanism of ferroptosis during sepsis will aid in developing improved therapeutic strategies.

Methods: We used the Gene Expression Omnibus database and FerrDb database to obtain ferroptosis-related differentially expressed genes (DEGs) between sepsis patients and healthy volunteers (HVs). Analyses of PPI networks, functional enrichment, as well as use of the MCODE algorithm were used to identify key ferroptosis-related DEGs. Expression of key ferroptosis-related DEGs was verified using: GSE57065 and GSE65682 datasets; rats in which ferroptosis was induced with erastin; sepsis-induced acute lung injury (siALI) rats. The effects of acupoint catgut embedding (ACE) on ferroptosis and expression of key ferroptosis-related DEGs in the lungs of siALI rats were also observed. A Cox proportional hazard model was used to verify the effect of key ferroptosis-related DEGs on the survival of sepsis patients. Cytoscape was used to construct ceRNA networks and gene–transcription factor networks.

Results: Between sepsis patients and HVs, we identified 33 ferroptosis-related DEGs. According to analyses of PPI networks and the MCODE algorithm, we obtained four modules, of which the most significant module contained nine ferroptosis-related DEGs. Functional-enrichment analyses showed that four of the nine DEGs were enriched in the MAPK signaling pathway: MAPK14, VEGFA, TGFBR1, and DUSP1. We verified expression of these four genes in GSE57065 and GSE65682 datasets and ferroptosis rats. In addition, expression of these four genes and that of the oxidative-stress indicators GSSG and MDA was upregulated, and glutathione peroxidase-4 (GPX4) expression was downregulated, in siALI rats, but ACE reversed these changes. The Cox proportional hazard model showed that survival of sepsis patients in the high-risk group was shorter than that in the low-risk group. We found that the XIST−hsa-let-7b-5p−TGFBR1/DUSP1 ceRNA network and transcription factor E2F1 may be important regulators of these four DEGs.

Conclusion: Our results suggest that MAPK14, VEGFA, TGFBR1, and DUSP1 may be key regulatory targets of ferroptosis in sepsis, and that ACE pretreatment may be antioxidant treatment for sepsis and alleviate ferroptosis. These findings provide a basis for further ferroptosis-related study in sepsis and provide new targets for its treatment.

Caveolin-1 identified as a key mediator of acute lung injury using bioinformatics and functional research

Acute lung injury (ALI) is a potentially life-threatening, devastating disease with an extremely high rate of mortality. The underlying mechanism of ALI is currently unclear. In this study, we aimed to confirm the hub genes associated with ALI and explore their functions and molecular mechanisms using bioinformatics methods. Five microarray datasets available in GEO were used to perform Robust Rank Aggregation (RRA) to identify differentially expressed genes (DEGs) and the key genes were identified via the protein-protein interaction (PPI) network. Lipopolysaccharide intraperitoneal injection was administered to establish an ALI model. Overall, 40 robust DEGs, which are mainly involved in the inflammatory response, protein catabolic process, and NF-κB signaling pathway were identified. Among these DEGs, we identified two genes associated with ALI, of which the CAV-1/NF-κB axis was significantly upregulated in ALI, and was identified as one of the most effective targets for ALI prevention. Subsequently, the expression of CAV-1 was knocked down using AAV-shCAV-1 or CAV-1-siRNA to study its effect on the pathogenesis of ALI in vivo and in vitro. The results of this study indicated that CAV-1/NF-κB axis levels were elevated in vivo and in vitro, accompanied by an increase in lung inflammation and autophagy. The knockdown of CAV-1 may improve ALI. Mechanistically, inflammation was reduced mainly by decreasing the expression levels of CD3 and F4/80, and activating autophagy by inhibiting AKT/mTOR and promoting the AMPK signaling pathway. Taken together, this study provides crucial evidence that CAV-1 knockdown inhibits the occurrence of ALI, suggesting that the CAV-1/NF-κB axis may be a promising therapeutic target for ALI treatment.

MicroRNA-451a and Th1/Th2 ratio inform inflammation, septic organ injury, and mortality risk in sepsis patients

Aims

MicroRNA-451a (miR-451a) regulates Th1/Th2 cell differentiation, inflammation, and septic organ injury in several experiments. Therefore, the present study aimed to explore the inter-correlation of miR-451a with the Th1/Th2 ratio, and their association with inflammation, septic organ injury, and mortality risk in patients with sepsis.

Methods

Consecutively, 117 patients with sepsis and 50 healthy controls (HCs) were enrolled. Peripheral blood mononuclear cell samples were collected to detect miR-451a expression and the Th1/Th2 ratio in all subjects.

Results

MiR-451a (p < 0.001), Th1 cells (p = 0.014), and the Th1/Th2 ratio (p < 0.001) increased, while Th2 cells (p < 0.001) declined in patients with sepsis compared with HCs. It was of note that miR-451a was positively correlated with Th1 cells (p = 0.002) and the Th1/Th2 ratio (p = 0.001), while it was negatively related to Th2 cells (p = 0.005) in patients with sepsis. Meanwhile, miR-451a and the Th1/Th2 ratio correlated with most of the following indexes: TNF-α, IL-1β, IL-6, C-reactive protein, sequential organ failure assessment (SOFA) score, or Acute Physiology and Chronic Health Evaluation II (APACHE II) score (most p < 0.05). Moreover, miR-451a (p < 0.001) and the Th1/Th2 ratio (p = 0.001) increased in deaths compared to survivors of sepsis; further ROC curve showed both miR-451a and the Th1/Th2 ratio possessed a certain value to predict mortality of patients with sepsis. Additionally, the Th1/Th2 ratio [odds ratio (OR): 2.052, p = 0.005] was independently related to 28-day mortality risk from multivariate logistic regression.

Conclusion

MiR-451a correlates with the Th1/Th2 ratio, and they both relate to inflammation, septic organ injury, and mortality risk in patients with sepsis.

Polymyxin B in Combination with Glycerol Monolaurate Exerts Synergistic Killing against Gram-Negative Pathogens

The rapid emergence and spread of multidrug-resistant (MDR) bacterial pathogens pose a serious danger to worldwide human health, and resistance to last-resort drugs, such as polymyxins, is being increasingly detected in MDR Gram-negative pathogens. There is an urgent need to find and optimize combination therapies as an alternative therapeutic strategy, with a dry pipeline in novel antibiotic research and development. We found a monoester formed from the combination of lauric acid and glycerol, glycerol monolaurate (GML), possessing prominent antibacterial and anti-inflammatory activity. However, it is still unclear whether GML in combination could increase antimicrobial activity. Here, we reported that polymyxin B (PMNB) combined with GML exhibited a synergistic antimicrobial impact on Gram-negative strains in vitro, including clinical MDR isolates. This synergistic antimicrobial activity correlated with the destruction of bacterial cell structures, eradication of preformed biofilms, and increased reactive oxygen species (ROS) accumulation. We also showed that PMNB synergized with GML effectively eliminated pathogens from bacterial pneumonia caused by Klebsiella pneumoniae to rescue mice. Our research demonstrated that the PMNB and GML combination induced synergistic antimicrobial activity for Gram-negative pathogens in vitro and in vivo. These findings are of great importance for treating bacterial infections and managing the spread of infectious diseases.

The inhibition of GLUT1-induced glycolysis in macrophage by phloretin participates in the protection during acute lung injury

The increased level of glycolysis in macrophage aggravates lipopolysaccharide (LPS)-induced acute lung injury (ALI). Glucose transporter 1 (GLUT1) serves as a ubiquitously expressed glucose transporter, which could activate inflammatory response by mediating glycolysis. Phloretin (PHL), an apple polyphenol, is also an inhibitor of GLUT1, possessing potent anti-inflammatory effects in various diseases. However, the potential role of PHL in ALI remains unclear till now. This study aims to investigate the impacts of PHL on ALI as well as its possible mechanisms. A mouse ALI model was established via intratracheal injection of LPS. LPS-induced primary macrophages were used to mimic in vitro ALI. Mice were pretreated with low or high dosage of PHL for 7 days via intragastric administration once a day before LPS injection. The results showed that PHL pretreatment significantly prevented LPS-induced lung pathological injury and inflammatory response. Meantime, PHL pretreatment also decreased the level of glycolysis in macrophage during ALI. In terms of mechanism, PHL inhibited the mRNA and protein expression of GLUT1. In vitro experiments further showed GLUT1 overexpression in macrophage by infection with lentivirus could abolish the inhibition of inflammation and glycolysis mediated by PHL, suggesting that GLUT1 was essential for the protection of PHL. Taken together, PHL pretreatment may protect against LPS-induced ALI by inhibiting glycolysis in macrophage in a GLUT1-dependent manner, which may be a candidate against ALI in the future.

Role of Caveolin-1 in Sepsis – A Mini-Review

Sepsis is a generalized disease characterized by an extreme response to a severe infection. Moreover, challenges remain in the diagnosis, treatment and management of septic patients. In this mini-review we demonstrate developments on cellular pathogenesis and the role of Caveolin-1 (Cav-1) in sepsis. Studies have shown that Cav-1 has a significant role in sepsis through the regulation of membrane traffic and intracellular signaling pathways. In addition, activation of apoptosis/autophagy is considered relevant for the progression and development of sepsis. However, how Cav-1 is involved in sepsis remains unclear, and the precise mechanisms need to be further investigated. Finally, the role of Cav-1 in altering cell permeability during inflammation, in sepsis caused by microorganisms, apoptosis/autophagy activation and new therapies under study are discussed in this mini-review.

WIN55212-2 alleviates acute lung injury by inhibiting macrophage glycolysis through the miR-29b-3p/FOXO3/PFKFB3 axis

BACKGROUND

Acute lung injury (ALI) is a severe organ dysfunction caused by sepsis. WIN55212-2 (WIN) is a cannabinoid receptor agonist. Activation of cannabinoid type 2 receptor can alleviate septic lung injury. Therefore, the effects of WIN on sepsis-related ALI were evaluated.

METHODS

MiR-29b-3p, FOXO3 and PFKFB3 levels, as well as M1 and M2 macrophage markers were assessed by RT-qPCR in MH-S cells after lipopolysaccharide (LPS) and WIN treatment. ChIP and dual luciferase reporter assays determined molecules interactions. Glycolysis-related proteins were evaluated by Western blotting assay. Lactic acid and ATP were also tested. Furthermore, the effect of WIN was tested in sepsis mice model. HE staining evaluated the histopathological changes in mouse lung tissues. The number of inflammatory cells and macrophages, protein concentration and lactic acid content were detected in mouse bronchoalveolar lavage fluid.

RESULTS

We found that WIN suppressed M1 polarization and glycolysis in alveolar macrophages induced by LPS. Moreover, WIN inhibited FOXO3 by up-regulating miR-29b-3p. Furthermore, we verified that FOXO3 induced macrophage M1 polarization and glycolysis through activating PFKFB3. In vivo, WIN alleviated ALI in mice with sepsis.

CONCLUSION

Our results reveal that WIN inhibits macrophage glycolysis through the miR-29b-3p/ FOXO3/PFKFB3 axis, suggesting new therapeutic targets to alleviate sepsis-related ALI.

Ropivacaine has the potential to relieve PM2.5‑induced acute lung injury

Ropivacaine is a commonly used local anesthetic in the clinic due to its low toxicity to the cardiovascular system or central nervous system, good tolerance and high clearance rate. The present study intended to investigate the effect of ropivacaine on PM2.5-induced acute lung injury (ALI) and reveal the underlying mechanism. After ropivacaine exposure, cell viability, oxidative stress and inflammation in PM2.5-induced BEAS-2B cells were assessed by Cell Counting Kit-8 and DCFH-DA staining, corresponding commercial kits and ELISA, respectively. The effects of ropivacaine on the expression of MMP9 and MMP12 and the proteins related to NLRP3/Caspase-1 signaling were then determined by western blot and reverse transcription-quantitative PCR analyses. In addition, NLR family pyrin domain containing 3 (NLRP3) agonist monosodium urate (MSU) was used to treat BEAS-2B cells followed by ropivacaine treatment and the effects on the above-mentioned cellular behaviors were determined again. The results indicated that the viability of BEAS-2B cells was decreased after PM2.5 induction, accompanied by aggravated oxidative stress and inflammation. However, ropivacaine alleviated oxidative stress and inflammation in PM2.5-induced BEAS-2B cells in a dose-dependent manner. Ropivacaine was also indicated to decrease the expression levels of NLRP3/Caspase-1 signaling-related proteins in PM2.5-induced BEAS-2B cells. Furthermore, cell viability was decreased, while oxidative stress and inflammatory response were aggravated, in PM2.5-induced BEAS-2B cells treated with MSU. In summary, the present results implied that ropivacaine exerted protective effects on PM2.5-induced ALI, and this effect may be related to NLRP3/Caspase-1 signaling.

IL35 attenuated LPS-induced acute lung injury by regulating macrophage polarization

BACKGROUND

Interleukin 35 (IL35) has been reported to play a role in acute lung injury (ALI); however, the current results regarding the relationship between IL35 and ALI are inconsistent. Therefore, we aimed to further determine the function of IL35 in ALI in mice and the potential mechanism in this paper.

MATERIALS AND METHODS

Hematoxylin-eosin (HE) staining and Masson staining were used to evaluate lung injury in mice. Immunohistochemical staining was used to evaluate the expression of IL35 p35, TLR4 and MD2 and the Bax/Bcl2 and p-P65/P65 ratios. The expression levels of IL35 EBi3, CD68, CD206 and MPO were assessed by immunofluorescence staining. RT-PCR was used to examine the expression levels of IL1β and IL6. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining was performed to detect apoptotic cells.

RESULTS

Overexpression of IL35 alleviated LPS-induced ALI in mice. IL35 overexpression decreased the expression of CD68 and increased the expression of CD206 in mice with ALI. Furthermore, upregulation of IL35 expression obviously reduced the expression of MPO, IL1β and IL6 in the lung tissues of mice with ALI. Mechanistically, IL35 suppressed the TLR4/NFκB-P65 pathway, leading to the promotion of the M1 to M2 macrophage transition and alleviation of inflammation in mice with ALI.

CONCLUSIONS

IL35 relieved LPS-induced inflammation and ALI in mice by regulating M1/M2 macrophage polarization and inhibiting the activation of the TLR4/NFκB-P65 pathway.

Impaired Alveolar Re-Epithelialization in Pulmonary Emphysema

Alveolar type II (ATII) cells are progenitors in alveoli and can repair the alveolar epithelium after injury. They are intertwined with the microenvironment for alveolar epithelial cell homeostasis and re-epithelialization. A variety of ATII cell niches, transcription factors, mediators, and signaling pathways constitute a specific environment to regulate ATII cell function. Particularly, WNT/β-catenin, YAP/TAZ, NOTCH, TGF-β, and P53 signaling pathways are dynamically involved in ATII cell proliferation and differentiation, although there are still plenty of unknowns regarding the mechanism. However, an imbalance of alveolar cell death and proliferation was observed in patients with pulmonary emphysema, contributing to alveolar wall destruction and impaired gas exchange. Cigarette smoking causes oxidative stress and is the primary cause of this disease development. Aberrant inflammatory and oxidative stress responses result in loss of cell homeostasis and ATII cell dysfunction in emphysema. Here, we discuss the current understanding of alveolar re-epithelialization and altered reparative responses in the pathophysiology of this disease. Current therapeutics and emerging treatments, including cell therapies in clinical trials, are addressed as well.

Mechanistic Understanding of Lung Inflammation: Recent Advances and Emerging Techniques

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury characterized by an acute inflammatory response in the lung parenchyma. Hence, it is considered as the most appropriate clinical syndrome to study pathogenic mechanisms of lung inflammation. ARDS is associated with increased morbidity and mortality in the intensive care unit (ICU), while no effective pharmacological treatment exists. It is very important therefore to fully characterize the underlying pathobiology and the related mechanisms, in order to develop novel therapeutic approaches. In vivo and in vitro models are important pre-clinical tools in biological and medical research in the mechanistic and pathological understanding of the majority of diseases. In this review, we will present data from selected experimental models of lung injury/acute lung inflammation, which have been based on clinical disorders that can lead to the development of ARDS and related inflammatory lung processes in humans, including ventilation-induced lung injury (VILI), sepsis, ischemia/reperfusion, smoke, acid aspiration, radiation, transfusion-related acute lung injury (TRALI), influenza, Streptococcus (S.) pneumoniae and coronaviruses infection. Data from the corresponding clinical conditions will also be presented. The mechanisms related to lung inflammation that will be covered are oxidative stress, neutrophil extracellular traps, mitogen-activated protein kinase (MAPK) pathways, surfactant, and water and ion channels. Finally, we will present a brief overview of emerging techniques in the field of omics research that have been applied to ARDS research, encompassing genomics, transcriptomics, proteomics, and metabolomics, which may recognize factors to help stratify ICU patients at risk, predict their prognosis, and possibly, serve as more specific therapeutic targets.

The pro-inflammatory effect of Staphylokinase contributes to community-associated Staphylococcus aureus pneumonia

Pneumonia caused by community-associated Staphylococcus aureus (CA-SA) has high morbidity and mortality, but its pathogenic mechanism remains to be further investigated. Herein, we identify that staphylokinase (SAK) is significantly induced in CA-SA and inhibits biofilm formation in a plasminogen-dependent manner. Importantly, SAK can enhance CA-SA-mediated pneumonia in both wild-type and cathelicidins-related antimicrobial peptide knockout (CRAMP^−/−) mice, suggesting that SAK exacerbates pneumonia in a CRAMP-independent manner. Mechanistically, SAK induces pro-inflammatory effects, especially in the priming step of NLRP3 inflammasome activation. Moreover, we demonstrate that SAK can increase K⁺ efflux, production of reactive oxygen species production, and activation of NF-κB signaling. Furthermore, the NLRP3 inflammasome inhibitor can counteract the effective of SAK induced CA-SA lung infection in mice. Taken together, we speculate that SAK exacerbates CA-SA-induced pneumonia by promoting NLRP3 inflammasome activation, providing new insights into the pathogenesis of highly virulent CA-SA and emphasizes the importance of controlling inflammation in acute pneumonia.

Staphylokinase (Sak) is highly prevalent in human-adapted S. aureus strains, with increased expression in community-associated (CA-SA) strains, promoting lung infection and activation of the NLRP3 inflammasome.

Risk factors for acute respiratory distress syndrome in sepsis patients: a retrospective study from a tertiary hospital in China

Background

Less is known about the risk factors for acute respiratory distress syndrome (ARDS) in sepsis patients diagnosed according to sepsis 3.0 criteria. Moreover, the risk factors for ARDS severity remain unclear.

Methods

We retrospectively collected the characteristics of sepsis patients from the intensive care unit of the First Affiliated Hospital of China Medical University from January 2017 to September 2018. Logistic regression was used in determining the risk factors.

Results

529 patients with sepsis were enrolled and 179 developed ARDS. The most common infection sites were acute abdominal infection (n = 304) and pneumonia (n = 117). Multivariate analysis showed that patients with pancreatitis with local infection (odds ratio [OR], 3.601; 95% confidence interval [CI], 1.429–9.073, P = 0.007), pneumonia (OR 3.486; 95% CI 1.890–6.430, P < 0.001), septic shock (OR 2.163; 95% CI 1.429–3.275, P < 0.001), a higher sequential organ failure assessment (SOFA) score (OR 1.241; 95% CI 1.155–1.333, P < 0.001) and non-pulmonary SOFA score (OR 2.849; 95% CI 2.113–3.841, P < 0.001) were independent risk factors for ARDS. Moreover, pneumonia is associated with increased severity of ARDS (OR 2.512; 95% CI 1.039–6.067, P = 0.041).

Conclusions

We determined five risk factors for ARDS in sepsis patients. Moreover, pneumonia is significantly associated with an increased severity of ARDS.

Emodin Ameliorates Acute Pancreatitis-Associated Lung Injury Through Inhibiting the Alveolar Macrophages Pyroptosis

Objective: To investigate the protective effect of emodin in acute pancreatitis (AP)-associated lung injury and the underlying mechanisms. Methods: NaT-AP model in rats was constructed using 3.5% sodium taurocholate, and CER+LPS-AP model in mice was constructed using caerulein combined with Lipopolysaccharide. Animals were divided randomly into four groups: sham, AP, Ac-YVAD-CMK (caspase-1 specific inhibitor, AYC), and emodin groups. AP-associated lung injury was assessed with H&E staining, inflammatory cytokine levels, and myeloperoxidase activity. Alveolar macrophages (AMs) pyroptosis was evaluated by flow cytometry. In bronchoalveolar lavage fluid, the levels of lactate dehydrogenase and inflammatory cytokines were measured by enzyme-linked immunosorbent assay. Pyroptosis-related protein expressions were detected by Western Blot. Results: Emodin, similar to the positive control AYC, significantly alleviated pancreas and lung damage in rats and mice. Additionally, emodin mitigated the pyroptotic process of AMs by decreasing the level of inflammatory cytokines and lactate dehydrogenase. More importantly, the protein expressions of NLRP3, ASC, Caspase1 p10, GSDMD, and GSDMD-NT in AMs were significantly downregulated after emodin intervention. Conclusion: Emodin has a therapeutic effect on AP-associated lung injury, which may result from the inhibition of NLRP3/Caspase1/GSDMD-mediated AMs pyroptosis signaling pathways.

Anti-Inflammatory Mechanisms of Total Flavonoids from Mosla scabra against Influenza A Virus-Induced Pneumonia by Integrating Network Pharmacology and Experimental Verification

Influenza virus is one of the most common infectious pathogens that could cause high morbidity and mortality in humans. However, the occurrence of drug resistance and serious complications extremely complicated the clinic therapy. Mosla scabra is a natural medicinal plant used for treating various lung and gastrointestinal diseases, including viral infection, cough, chronic obstructive pulmonary disease, acute gastroenteritis, and diarrhoea. But the therapeutic effects of this herbal medicine had not been expounded clearly. In this study, a network pharmacology approach was employed to investigate the protective mechanism of total flavonoids from M. scabra (MSTF) against influenza A virus- (IAV-) induced acute lung damage and inflammation. The active compounds of MSTF were analyzed by LC-MS/MS and then evaluated according to their oral bioavailability and drug-likeness index. The potential targets of each active compound in MSTF were identified by using PharmMapper Server, whereas the potential genes involved in IAV infection were obtained from GeneGards. The results showed that luteoloside, apigenin, kaempherol, luteolin, mosloflavone I, and mosloflavone II were the main bioactive compounds found in MSTF. Primarily, 23 genes were identified as the targets of those five active compounds, which contributed to the inactivation of chemical carcinogenesis ROS, lipid and atherosclerosis, MAPK signaling pathway, pathways in cancer, PI3K-AKT signaling pathway, proteoglycans in cancer, and viral carcinogenesis. Finally, the animal experiments validated that MSTF improved IAV-induced acute lung inflammation via inhibiting MAPK, PI3K-AKT, and oxidant stress pathways. Therefore, our study demonstrated the potential inhibition of MSTF on viral pneumonia in mice and provided a strategy to characterize the molecular mechanism of traditional Chinese medicine by a combinative method using network pharmacology and experimental validation.

Comprehensive Analysis of Potential ceRNA Network and Different Degrees of Immune Cell Infiltration in Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a leading cause of death in critically ill patients due to hypoxemic respiratory failure. The specific pathogenesis underlying ARDS has not been fully elucidated. In this study, we constructed a triple regulatory network involving competing endogenous RNA (ceRNA) to investigate the potential mechanism of ARDS and evaluated the immune cell infiltration patterns in ARDS patients. Overall, we downloaded three microarray datasets that included 60 patients with sepsis-induced ARDS and 79 patients with sepsis alone from the public Gene Expression Omnibus (GEO) database and identified differentially expressed genes (DEGs, including 9 DElncRNAs, 9 DEmiRNAs, and 269 DEmRNAs) by R software. The DEGs were subjected to the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) for functional enrichment analysis, and a protein–protein interaction (PPI) network was generated for uncovering interactive relationships among DEmRNAs. Then, a ceRNA network that contained 5 DElncRNAs, 7 DEmiRNAs, and 71 DEmRNAs was established according to the overlapping genes in both DEGs and predicted genes by public databases. Finally, we identified the TUG1/miR-140-5p/NFE2L2 pathway as the hub pathway in the whole network through Cytoscape. In addition, we evaluated the distribution of 22 subtypes of immune cells and recognized three differentially expressed immune cells in patients with sepsis-induced ARDS by “Cell Type Identification by Estimating Relative Subsets of Known RNA Transcripts (CIBERSORT)” algorithm, namely, naive B cells, regulatory T cells, and eosinophils. Correlations between differentially expressed immune cells and hub genes in the ceRNA network were also performed. In conclusion, we demonstrated a new potential regulatory mechanism underlying ARDS (the TUG1/miR-140-5p/NFE2L2 ceRNA regulatory pathway), which may help in further exploring the pathogenesis of ARDS.

ACT001 suppressing M1 polarization against inflammation via NF-κB and STAT1 signaling pathways alleviates acute lung injury in mice

ACT001 has been shown to exhibit excellent antitumor and anti-fibrosis activities. However, the role of ACT001 in acute lung injury (ALI) and the underlying mechanism remains largely unclear. The present study aimed to investigate the protective effects of ACT001 on ALI and explore the potential mechanisms. Herein, we firstly established the ALI mouse model induced by intratracheal instillation of lipopolysaccharide (LPS). ACT001 treatment significantly alleviated histopathological changes of lung tissues with lower infiltration of pulmonary M1 macrophages in ALI mice. Then, we performed in vitro experiment and found that ACT001 treatment effectively inhibited the M1 phenotype of RAW264.7 and THP-1.. Next, we performed pull-down and mass spectrometry analysis to screen the interacting proteins of ACT001, identifying IKKβ and STAT1 as the critical target proteins of ACT001. And ACT001 treatment significantly suppressed the NF-κB and STAT1 pathways, thereby inhibiting the M1 polarization against inflammation in vivo and in vitro. Finally, we used IMD 0354 (IMD) and Fludarabine (Flud) to specifically block the activity of IKKβ and STAT1, and stimulated macrophages through IKKβ and STAT1 overexpression. Our data clearly showed that ACT001-induced decrease of the M1 polarization was blocked by IMD and Flud treatment, and reversed by IKKβ and STAT1 overexpression in RAW264.7 cells. In conclusion, we discovered that ACT001 significantly alleviates inflammation and limits M1 phenotype of pulmonary macrophages via suppressing NF-κB and STAT1 signaling pathways, providing new insights for the development of drugs to treat ALI/ARDS.

Intestinal Microbiota - An Unmissable Bridge to Severe Acute Pancreatitis-Associated Acute Lung Injury

Severe acute pancreatitis (SAP), one of the most serious abdominal emergencies in general surgery, is characterized by acute and rapid onset as well as high mortality, which often leads to multiple organ failure (MOF). Acute lung injury (ALI), the earliest accompanied organ dysfunction, is the most common cause of death in patients following the SAP onset. The exact pathogenesis of ALI during SAP, however, remains unclear. In recent years, advances in the microbiota-gut-lung axis have led to a better understanding of SAP-associated lung injury (PALI). In addition, the bidirectional communications between intestinal microbes and the lung are becoming more apparent. This paper aims to review the mechanisms of an imbalanced intestinal microbiota contributing to the development of PALI, which is mediated by the disruption of physical, chemical, and immune barriers in the intestine, promotes bacterial translocation, and results in the activation of abnormal immune responses in severe pancreatitis. The pathogen-associated molecular patterns (PAMPs) mediated immunol mechanisms in the occurrence of PALI via binding with pattern recognition receptors (PRRs) through the microbiota-gut-lung axis are focused in this study. Moreover, the potential therapeutic strategies for alleviating PALI by regulating the composition or the function of the intestinal microbiota are discussed in this review. The aim of this study is to provide new ideas and therapeutic tools for PALI patients.

Shp2 in Alveolar Macrophages Regulates Macrophage I Phenotype in Acute Lung Injury

Macrophage play important role in acute lung injury (ALI). This study aims to explore the possible role of Shp2 in regulating macrophage 1 (M1) in ALI progression. ALI was induced in rats by intravenous injection of lipopolysacharide (LPS). Lentivirus was used to knock down Shp2 expression. Lungs from LPS-induced ALI rats were evaluated by H&E staining and wet/dry lung weight ratio (W/D ratio) measurement. The expression of inflammatory cytokines IL-1β, TNF-α and IL-6 in bronchoalveolar lavage fluid were detected by ELISA. The expressions of M1 biomarker (iNOS) and macrophage 2 (M2) biomarker (Arg-1) in lung tissues and macrophages were measured by immunofluorescence and western blot. The ratio of M2/M1 was detected by flow cytometry. Inflammatory cytokines were highly expressed in ALI rat models, in which elevated expression of iNOS and decreased Arg-1 expression were detected. Shp2 was found to be highly expressed in lung tissues of ALI rat models. LPS treatment in NR8383 cells lead to increased M1 phenotype and elevated expression of Shp2. Suppression on Shp2 expression can counteract the LPS-induced effect and further attenuate ALI progression. Evidence collected from ALI rat and cell models showed that suppression Shp2 expression in macrophages can inhibit M1 phenotype to attenuate ALI progression.

Mast Cells Drive Systemic Inflammation and Compromised Bone Repair After Trauma

There is evidence that mast cells contribute to inflammation induced by hemorrhagic shock, severe tissue injury or sepsis. Mast cells are highly responsive to alarm signals generated after trauma, and release many inflammatory mediators including interleukin-6, a key mediator of posttraumatic inflammation. An overwhelming posttraumatic inflammation causes compromised bone healing; however, the underlying cellular and molecular mechanisms are poorly understood. Recently, we found that mast cells trigger local and systemic inflammation after isolated fracture leading to uneventful bone repair. Here, we investigated whether mast cells critically contribute to trauma-induced compromised bone healing. Male Mcpt5-Cre⁺ R-DTA mice, which lack connective tissue type mast cells, and their mast cell-competent Cre^- littermates underwent a femur fracture with/without thoracic trauma. Posttraumatic systemic and local inflammation and bone repair were assessed 3 h and 21 d post injury. Both, the systemic and pulmonary inflammation was significantly increased in mast cell-competent mice upon combined trauma compared to isolated fracture. In mast cell-deficient mice, the increase of inflammatory mediators in the circulation induced by the severe trauma was abolished. In the bronchoalveolar lavage fluid, the trauma-induced increase of inflammatory cytokines was not reduced, but the neutrophil invasion into the lungs was significantly diminished in the absence of mast cells. Locally in the fracture hematoma, mast cell-competent mice displayed reduced inflammatory mediator concentrations after combined trauma compared to isolated fracture, which was abolished in mast cell-deficient mice. Notably, while combined trauma resulted in compromised bone repair in mast cell-competent mice, indicated by significantly reduced bone and increased cartilage fracture callus contents, this was abolished in Mcpt5-Cre⁺ R-DTA mice. Therefore, mast cells contribute to trauma-induced compromised bone repair and could be a potential target for new treatment options to improve fracture healing in multiply injured patients.

MicroRNAs: Important Regulatory Molecules in Acute Lung Injury/Acute Respiratory Distress Syndrome

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is an overactivated inflammatory response caused by direct or indirect injuries that destroy lung parenchymal cells and dramatically reduce lung function. Although some research progress has been made in recent years, the pathogenesis of ALI/ARDS remains unclear due to its heterogeneity and etiology. MicroRNAs (miRNAs), a type of small noncoding RNA, play a vital role in various diseases. In ALI/ARDS, miRNAs can regulate inflammatory and immune responses by targeting specific molecules. Regulation of miRNA expression can reduce damage and promote the recovery of ALI/ARDS. Consequently, miRNAs are considered as potential diagnostic indicators and therapeutic targets of ALI/ARDS. Given that inflammation plays an important role in the pathogenesis of ALI/ARDS, we review the miRNAs involved in the inflammatory process of ALI/ARDS to provide new ideas for the pathogenesis, clinical diagnosis, and treatment of ALI/ARDS.

Neutrophil Recruitment in Pneumococcal Pneumonia

Streptococcus pneumoniae (Spn) is the primary agent of community-acquired pneumonia. Neutrophils are innate immune cells that are essential for bacterial clearance during pneumococcal pneumonia but can also do harm to host tissue. Neutrophil migration in pneumococcal pneumonia is therefore a major determinant of host disease outcomes. During Spn infection, detection of the bacterium leads to an increase in proinflammatory signals and subsequent expression of integrins and ligands on both the neutrophil as well as endothelial and epithelial cells. These integrins and ligands mediate the tethering and migration of the neutrophil from the bloodstream to the site of infection. A gradient of host-derived and bacterial-derived chemoattractants contribute to targeted movement of neutrophils. During pneumococcal pneumonia, neutrophils are rapidly recruited to the pulmonary space, but studies show that some of the canonical neutrophil migratory machinery is dispensable. Investigation of neutrophil migration is necessary for us to understand the dynamics of pneumococcal infection. Here, we summarize what is known about the pathways that lead to migration of the neutrophil from the capillaries to the lung during pneumococcal infection.

Huangkui Capsule Attenuates Lipopolysaccharide-Induced Acute Lung Injury and Macrophage Activation by Suppressing Inflammation and Oxidative Stress in Mice

Background

Huangkui capsule (HKC) comprises the total flavonoid extract of flowers of Abelmoschus manihot (L.) Medicus. This study aimed to explore the effects of HKC on lipopolysaccharide- (LPS-) induced acute lung injury (ALI) in mice and LPS-stimulated RAW 264.7 cells.

Methods

Enzyme-linked immunosorbent assay, histopathology, spectrophotometry, and quantitative real-time polymerase chain reaction were used for the assessments. Statistical analysis was performed using a one-way analysis of variance.

Results

LPS significantly increased lung inflammation, neutrophil infiltration, and oxidative stress and downregulated lung miR-451 expression. Treatment with HKC dramatically, reduced the total cell count in the bronchoalveolar lavage fluid (BALF), and inhibited myeloperoxidase activity in the lung tissues 24 h after LPS challenge. Histopathological analysis demonstrated that HKC attenuated LPS-induced tissue oedema and neutrophil infiltration in the lung tissues. Additionally, the concentrations of tumour necrosis factor- (TNF-) α and interleukin- (IL-) 6 in BALF and IL-6 in the plasma reduced after HKC administration. Moreover, HKC could enhance glutathione peroxidase and catalase activities and upregulate the expression of miR-451 in the lung tissues. In vitro experiments revealed that HKC inhibited the production of nitric oxide, TNF-α, and IL-6 in LPS-induced RAW 264.7 cells and mouse primary peritoneal macrophages. Additionally, HKC downregulated LPS-induced transcription of TNF-α and IL-6 in RAW 264.7 cells.

Conclusions

These findings suggest that HKC has anti-inflammatory and antioxidative effects that may protect mice against LPS-induced ALI and macrophage activation.

Inhibition of lipopolysaccharide-induced inflammatory responses by 1'-acetoxychavicol acetate

Lipopolysaccharide on gram negative bacteria can be detected by Toll-like receptor 4 (TLR4) to elicit a series of innate immune responses, leading to inflammation to eliminate the targeted pathogen. However, dysregulation in the responses results in excessive inflammation. The 1'-acetoxychavicol acetate (ACA) is a bioactive compound originated from Alpinia species known to have anti-inflammatory and apoptosis-inducing properties. Here, we found that ACA inhibits lipopolysaccharide-induced expression and production of proinflammatory cytokines such as interleukin 6 and TNFα by macrophages. ACA suppresses the activation of NF-κB and MAP kinases in TLR4 signaling. Moreover, ACA also inhibits TLR4-mediated induction of type I interferon by suppressing IRF3 activation. In lipopolysaccharide-challenged mice, ACA treatment successfully increased the survival of mice and alleviated inflammation in the lung. Thus, ACA is a potential anti-inflammatory agent to regulate excessive inflammation. This article is protected by copyright. All rights reserved.

Melatonin attenuates LPS-induced pyroptosis in acute lung injury by inhibiting NLRP3-GSDMD pathway via activating Nrf2/HO-1 signaling axis

Acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS) is featured by intensive inflammatory responses and oxidative stress, which lead to cytokine storms and pyroptosis. Here, we aimed to investigate whether melatonin was capable of alleviating LPS-induced ALI via activating the nuclear factor erythroid 2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signaling axis and inhibiting pyroptosis. Mice were injected with melatonin (30 mg/kg) intraperitoneally for consecutive five days before LPS instillation intratracheally, and human alveolar epithelial cell (AECⅡ) A549 cell lines and murine macrophages Raw264.7 cell lines were pretreated with melatonin (400 μM) before LPS (10 μg/ml) stimulation. The result demonstrated that LPS induced obvious lung injury characterized by alveolar damage, neutrophil infiltration and lung edema as well as the reduction of the survival rate of mice, which were totally reversed by melatonin pretreatment. Mechanistically, melatonin pretreatment activated nuclear factor erythroid2-related factor (Nrf) 2 signaling, subsequently, drove antioxidant pathways including significant increases in the expression of Nrf2, HO-1, NQO1, Mn-SOD and Catalase in vivo and in vitro. Simultaneously, melatonin inhibited ROS and MDA overproduction, iNOS expression as well as TNF-α and IL-1β expression and release. Furthermore, melatonin inhibited LPS-induced pyroptosis by reversing the overexpression of NLRP3, Caspase-1, IL-1β, IL-18 and GSDMD-N, as well as LDH release and TUNEL-positive cells in A549 cells and Raw264.7 cells. Overall, the current study suggests that melatonin exerts protective roles on LPS-induced ALI and pyroptosis by inhibiting NLRP3-GSDMD pathway via activating Nrf2/HO-1 signaling axis.

PEP-sNASP Peptide Alleviates LPS-Induced Acute Lung Injury Through the TLR4/TRAF6 Axis

Acute lung injury (ALI) is a severe inflammatory lung disease associated with macrophages. Somatic nuclear autoantigenic sperm protein (sNASP) is a negative regulator of Toll-like receptor (TLR) signaling that targets tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) in macrophages, which is required to maintain homeostasis of the innate immune response. In the present study, we generated a cell permeable PEP-sNASP peptide using the sNASP protein N-terminal domain, and examined its potential therapeutic effect in a mouse model of ALI induced by the intranasal administration of lipopolysaccharide (LPS) and elucidated the underlying molecular mechanisms in RAW 264.7 cells. In vivo, PEP-sNASP peptide treatment markedly ameliorated pathological injury, reduced the wet/dry (W/D) weight ratio of the lungs and the production of proinflammatory cytokines (interleukin (IL)-1β, IL-6, and TNF-α). In vitro, we demonstrated that when the PEP-sNASP peptide was transduced into RAW 264.7 cells, it bound to TRAF6, which markedly decreased LPS-induced proinflammatory cytokines by inhibiting TRAF6 autoubiquitination, nuclear factor (NF)-κB activation, reactive oxygen species (ROS) and cellular nitric oxide (NO) levels. Furthermore, the PEP-sNASP peptide also inhibited NLR family pyrin domain containing 3 (NLRP3) inflammasome activation. Our results therefore suggest that the PEP-sNASP may provide a potential protein therapy against oxidative stress and pulmonary inflammation via selective TRAF6 signaling.

FGF21 improves LPS-induced pulmonary microvascular endothelial cell dysfunction and inflammatory response through SIRT1-mediated NF-κB deacetylation

Pneumonia is a common infectious disease of the respiratory system in children. It often leads to death in children by causing acute lung injury. Fibroblast growth factor 21 (FGF21) is a peptide hormone that plays important role in the regulation of energy homeostasis. This study aimed to investigate the role of FGF21 in alleviating the lipopolysaccharide (LPS)-induced human pulmonary microvascular endothelial cell (HPMEC) injury, as well as the underlying mechanism. The expression of SIRT1, NF-κB p65, Ac-NF-κB p65, apoptosis-related proteins, tight junction proteins and adhesion molecules in HPMECs. The viability and apoptosis of HPMECs was detected by CCK-8 and Tunel assays. LDH level and levels of inflammatory factors were respectively determined by assay kits. The mRNA expression of adhesion molecules in HPMECs was analyzed by RT-qPCR. As a result, SIRT1 expression was decreased and expression of NF-κB p65 and Ac-NF-κB p65 was increased in LPS-induced HPMECs, which were reversed by rFGF21. rFGF21 increased the viability and inhibited the apoptosis, inflammatory response, permeability and release of cell adhesion molecules of LPS-induced HPMECs. In addition, EX527 as SIRT1 inhibitor, could reversed the effect of rFGF21 on LPS-induced HPMECs. In conclusion, FGF21 improved LPS-induced HPMECs dysfunction and inflammatory response through SIRT1-mediated NF-κB deacetylation.

Cell Type-Specific Roles of STAT3 Signaling in the Pathogenesis and Progression of K-ras Mutant Lung Adenocarcinoma

Simple Summary

Lung adenocarcinomas with mutations in the K-ras gene are hard to target pharmacologically and highly lethal. As a result, there is a need to identify other therapeutic targets that influence K-ras oncogenesis. One contender is STAT3, a transcription factor that is associated with K-ras mutations and aids tumor development and progression through tumor cell intrinsic and extrinsic mechanisms. In this review, we summarize the lung epithelial and infiltrating immune cells that express STAT3, the roles of STAT3 in K-ras mutant lung adenocarcinoma, and therapies that may be able to target STAT3.

Abstract

Worldwide, lung cancer, particularly K-ras mutant lung adenocarcinoma (KM-LUAD), is the leading cause of cancer mortality because of its high incidence and low cure rate. To treat and prevent KM-LUAD, there is an urgent unmet need for alternative strategies targeting downstream effectors of K-ras and/or its cooperating pathways. Tumor-promoting inflammation, an enabling hallmark of cancer, strongly participates in the development and progression of KM-LUAD. However, our knowledge of the dynamic inflammatory mechanisms, immunomodulatory pathways, and cell-specific molecular signals mediating K-ras-induced lung tumorigenesis is substantially deficient. Nevertheless, within this signaling complexity, an inflammatory pathway is emerging as a druggable target: signal transducer and activator of transcription 3 (STAT3). Here, we review the cell type-specific functions of STAT3 in the pathogenesis and progression of KM-LUAD that could serve as a new target for personalized preventive and therapeutic intervention for this intractable form of lung cancer.

Electroacupuncture Pretreatment Exhibits Lung Protective and Anti-Inflammation Effects in Lipopolysaccharide-Induced Acute Lung Injury via SIRT1-Dependent Pathways

To investigate the effect of electroacupuncture (EA) on acute lung injury (ALI), a lipopolysaccharide (LPS) induced ALI mouse model was used in this study. Before receiving intratracheal LPS instillation, mice were given EA at ST36 for 7 days as a long-term treatment or one time as a short-term treatment. Lung histopathological examination, lung injury scores, lung wet/dry (W/D) ratio, and inflammatory cytokines included proinflammation factors such as TNF-α, IL-1β, and IL-6 and anti-inflammation factors such as IL-4 and IL-10 in serum and bronchoalveolar lavage fluid (BALF) were detected at the end of experiment. The results show that EA pretreatment ameliorated the lung damage and inflammatory response by LPS. In addition, we found that SIRT1 and its deacetylation of NF-κB were promoted after EA pretreatment in lung tissues. Meanwhile, the expression of angiotensin-converting enzyme 2 (ACE2) is also enhanced by EA pretreatment. Thus, the present findings suggest that EA could be a potential therapy of ALI.

Exosomes from Human Placenta Choriodecidual Membrane-Derived Mesenchymal Stem Cells Mitigate Endoplasmic Reticulum Stress, Inflammation, and Lung Injury in Lipopolysaccharide-Treated Obese Mice

Endoplasmic reticulum (ER) stress mediates the effects of obesity on aggravating sepsis-induced lung injury. We investigated whether exosomes from human placenta choriodecidual membrane-derived mesenchymal stem cells (pcMSCs) can mitigate pulmonary ER stress, lung injury, and the mechanisms of inflammation, oxidation, and apoptosis in lipopolysaccharide-treated obese mice. Diet-induced obese (DIO) mice (adult male C57BL/6J mice fed with a 12-week high-fat diet) received lipopolysaccharide (10 mg/kg, i.p.; DIOLPS group) or lipopolysaccharide plus exosomes (1 × 108 particles/mouse, i.p.; DIOLPSExo group). Our data demonstrated lower levels of ER stress (upregulation of glucose-regulated protein 78, phosphorylated eukaryotic initiation factor 2α, and C/EBP homologous protein; p = 0.038, <0.001, and <0.001, respectively), inflammation (activation of nuclear factor-kB, hypoxia-inducible factor-1α, macrophages, and NLR family pyrin domain containing 3; upregulation of tumor necrosis factor-α, interleukin-1β, and interleukin-6; p = 0.03, <0.001, <0.001, <0.001, <0.001, <0.001, and <0.001, respectively), lipid peroxidation (p < 0.001), and apoptosis (DNA fragmentation, p = 0.003) in lung tissues, as well as lower lung injury level (decreases in tidal volume, peak inspiratory flow, and end expiratory volume; increases in resistance, injury score, and tissue water content; p < 0.001, <0.001, <0.001, <0.001, <0.001, and =0.002, respectively) in the DIOLPSExo group than in the DIOLPS group. In conclusion, exosomes from human pcMSCs mitigate pulmonary ER stress, inflammation, oxidation, apoptosis, and lung injury in lipopolysaccharide-treated obese mice.