LPS-induced Acute Lung Injury Involves NF-κB-mediated Downregulation of SOX18

CLDN5: From structure and regulation to roles in tumors and other diseases beyond CNS disorders

Claudin-5 (CLDN5) is an essential component of tight junctions (TJs) and is critical for the integrity of the blood-brain barrier (BBB), ensuring homeostasis and protection from damage to the central nervous system (CNS). Currently, many researchers have summarized the role and mechanisms of CLDN5 in CNS diseases. However, it is noteworthy that CLDN5 also plays a significant role in tumor growth and metastasis. In addition, abnormal CLDN5 expression is involved in the development of respiratory diseases, intestinal diseases, cardiac diseases, and diabetic ocular complications. This paper aims to review the structure, expression, and regulation of CLDN5, focusing on its role in tumors, including its expression and regulation, effects on malignant phenotypes, and clinical significance. Furthermore, this paper will provide an overview of the role and mechanisms of CLDN5 in respiratory diseases, intestinal diseases, cardiac diseases, and diabetic ocular complications.

Role of Gasotransmitters in Inflammatory Edema

Significance: Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are, to date, the identified members of the gasotransmitter family, which consists of gaseous signaling molecules that play central roles in the regulation of a wide variety of physiological and pathophysiological processes, including inflammatory edema. Recent Advances: Recent studies show the potential anti-inflammatory and antiedematogenic effects of NO-, CO-, and H2S-donors in vivo. In general, it has been observed that the therapeutical effects of NO-donors are more relevant when administered at low doses at the onset of the inflammatory process. Regarding CO-donors, their antiedematogenic effects are mainly associated with inhibition of proinflammatory mediators (such as inducible NO synthase [iNOS]-derived NO), and the observed protective effects of H2S-donors seem to be mediated by reducing some proinflammatory enzyme activities. Critical Issues: The most recent investigations focus on the interactions among the gasotransmitters under different pathophysiological conditions. However, the biochemical/pharmacological nature of these interactions is neither general nor fully understood, although specifically dependent on the site where the inflammatory edema occurs. Future Directions: Considering the nature of the involved mechanisms, a deeper knowledge of the interactions among the gasotransmitters is mandatory. In addition, the development of new pharmacological tools, either donors or synthesis inhibitors of the three gasotransmitters, will certainly aid the basic investigations and open new strategies for the therapeutic treatment of inflammatory edema. Antioxid. Redox Signal. 40, 272-291.

Molecular Mechanism of SOX18 in Lipopolysaccharide-Induced Injury of Human Umbilical Vein Endothelial Cells

Endothelial dysfunction is associated with the progression of sepsis. This study sought to probe the molecular route of sex-determining region on the Y chromosome-box transcription factor 18 (SOX18) in sepsis-associated endothelial injury. Human umbilical vein endothelial cells (HUVECs) were treated with lipopolysaccharide (LPS) to establish the sepsis cell model. Cell viability, lactate dehydrogenase (LDH) release, oxidative stress (reactive oxygen species/malondialdehyde/superoxide dismutase), and inflammation (interleukin-1β/tumor necrosis factor-α/interleukin-6) were evaluated by cell counting kit-8 assay and relevant assay kits. The expression levels of SOX18, microRNA (miR)-204-5p, and cadherin-2 (CDH2) in cells were determined by real-time quantitative polymerase chain reaction and Western blot assay. The interaction of SOX18, miR-204-5p, and CDH2 was analyzed by chromatin immunoprecipitation and dual-luciferase assay. LPS induced HUVECs injury and downregulation of SOX18. SOX18 overexpression increased cell viability, while decreased LDH activity, oxidative stress, and inflammation. SOX18 bound to the miR-204-5p promoter to promote miR-204-5p expression, and further repressed CDH2 expression. miR-204-5p knockdown and CDH2 overexpression abrogated the protective role of SOX18 in HUVECs injury. Overall, SOX18 alleviated LPS-induced injury of HUVECs by promoting miR-204-5p and repressing CDH2, suggesting it as a potential target for sepsis treatment.

CAV1 and KRT5 are potential targets for prostate cancer

Prostate cancer is the most common malignant tumor of male urogenital system that occurs in prostate epithelium. However, relationship between CAV1 and KRT5 and prostate cancer remains unclear. The prostate cancer datasets GSE114740 and GSE200879 were downloaded from Gene Expression Omnibus generated by GPL11154 and GPL32170. De-batch processing was performed, differentially expressed genes (DEGs) were screened, and weighted gene co-expression network analysis. The construction and analysis of protein-protein interaction network, functional enrichment analysis, gene set enrichment analysis. Gene expression heat map was drawn and immune infiltration analysis was performed. Comparative toxicogenomics database analysis were performed to find the disease most related to core gene. In addition, the cell experiment was performed to verify the role of CAV1 and KRT5 by western blot. Divided into 4 groups: control, prostate cancer, prostate cancer-over expression, and prostate cancer- knock out. TargetScan screened miRNAs that regulated central DEGs; 770 DEGs were identified. According to Gene Ontology analysis, they were mainly concentrated in actin binding and G protein coupled receptor binding. In Kyoto Encyclopedia of Gene and Genome analysis, they were mainly concentrated in PI3K-Akt signal pathway, MAPK signal pathway, and ErbB signal pathway. The intersection of enrichment terms of differentially expressed genes and GOKEGG enrichment terms was mainly concentrated in ErbB signaling pathway and MAPK signaling pathway. Three important modules were generated. The protein-protein interaction network obtained 8 core genes (CAV1, BDNF, TGFB3, FGFR1, PRKCA, DLG4, SNAI2, KRT5). Heat map of gene expression showed that core genes (CAV1, TGFB3, FGFR1, SNAI2, KRT5) are highly expressed in prostate cancer tissues and low in normal tissues. Comparative toxicogenomics database analysis showed that core genes (CAV1, TGFB3, FGFR1, SNAI2, KRT5) were associated with prostate tumor, cancer, tumor metastasis, necrosis, and inflammation. CAV1 and KRT5 are up-regulated in prostate cancer. CAV1 and KRT5 are highly expressed in prostate cancer. The higher expression of CAV1 and KRT5, the worse prognosis.

Phytochemical investigation, antibacterial, and ameliorative potential effects of Tamarix nilotica on LPS-induced acute lung injury model in mice

Acute lung injury (ALI) is a serious illness with a high mortality rate of 40-60%. It is characterised by systemic inflammatory processes and oxidative stress. Gram-negative bacterial infections are the major cause of ALI, and lipopolysaccharide (LPS) is the major stimulus for the release of inflammatory mediators. Hence, there is an urgent need to develop new therapies which ameliorate ALI and prevent its serious consequences. The Middle Eastern native plant Tamarix nilotica (Ehrenb) Bunge belongs to the family Tamaricaceae, which exhibits strong anti-inflammatory and antioxidant effects. Thus, the current work aimed to ensure the plausible beneficial effects of T. nilotica different fractions on LPS-induced acute lung injury after elucidating their phytochemical constituents using LC/MS analysis. Mice were randomly allocated into six groups: Control saline, LPS group, and four groups treated with total extract, DCM, EtOAc and n-butanol fractions, respectively, intraperitoneal at 100 mg/kg doses 30 min before LPS injection. The lung expression of iNOS, TGF-β1, NOX-1, NOX-4 and GPX-1 levels were evaluated. Also, oxidative stress was assessed via measurements of MDA, SOD and Catalase activity, and histopathological and immunohistochemical investigation of TNF-α in lung tissues were performed. T. nilotica n-butanol fraction caused a significant downregulation in iNOS, TGF-β1, TNF-α, NOX-1, NOX-4, and MDA levels (p ˂ 0.05), and significantly elevated GPX-1 expression levels, SOD, and catalase activity (p ˂ 0.05), and alleviated all histopathological abnormalities confirming its advantageous role in ALI. The antibacterial activities of T. nilotica and its different fractions were investigated by agar well diffusion method and broth microdilution method. Interestingly, the n-butanol fraction exhibited the best antibacterial activity against Klebsiella pneumoniae clinical isolates. It also significantly reduced exopolysaccharide quantity, cell surface hydrophobicity, and biofilm formation.

A systematic review of the research progress of traditional Chinese medicine against pulmonary fibrosis: from a pharmacological perspective

Pulmonary fibrosis is a chronic progressive interstitial lung disease caused by a variety of etiologies. The disease can eventually lead to irreversible damage to the lung tissue structure, severely affecting respiratory function and posing a serious threat to human health. Currently, glucocorticoids and immunosuppressants are the main drugs used in the clinical treatment of pulmonary fibrosis, but their efficacy is limited and they can cause serious adverse effects. Traditional Chinese medicines have important research value and potential for clinical application in anti-pulmonary fibrosis. In recent years, more and more scientific researches have been conducted on the use of traditional Chinese medicine to improve or reduce pulmonary fibrosis, and some important breakthroughs have been made. This review paper systematically summarized the research progress of pharmacological mechanism of traditional Chinese medicines and their active compounds in improving or reducing pulmonary fibrosis. We conducted a systematic search in several main scientific databases, including PubMed, Web of Science, and Google Scholar, using keywords such as idiopathic pulmonary fibrosis, pulmonary fibrosis, interstitial pneumonia, natural products, herbal medicine, and therapeutic methods. Ultimately, 252 articles were included and systematically evaluated in this analysis. The anti-fibrotic mechanisms of these traditional Chinese medicine studies can be roughly categorized into 5 main aspects, including inhibition of epithelial-mesenchymal transition, anti-inflammatory and antioxidant effects, improvement of extracellular matrix deposition, mediation of apoptosis and autophagy, and inhibition of endoplasmic reticulum stress. The purpose of this article is to provide pharmaceutical researchers with information on the progress of scientific research on improving or reducing Pulmonary fibrosis with traditional Chinese medicine, and to provide reference for further pharmacological research.

Inflammation and coagulation abnormalities via the activation of the HMGB1‑RAGE/NF‑κB and F2/Rho pathways in lung injury induced by acute hypoxia

High‑altitude acute hypoxia is commonly associated with respiratory cardiovascular diseases. The inability to adapt to acute hypoxia may lead to cardiovascular dysfunction, lung injury and even death. Therefore, understanding the molecular basis of the adaptation to high‑altitude acute hypoxia may reveal novel therapeutic approaches with which to counteract the detrimental consequences of hypoxia. In the present study, a high‑altitude environment was simulated in a rat model in order to investigate the role of the high mobility group protein‑1 (HMGB1)/receptor for advanced glycation end products (RAGE)/NF‑κB and F2/Rho signaling pathways in lung injury induced by acute hypoxia. It was found that acute hypoxia caused inflammation through the HMGB1/RAGE/NF‑κB pathway and coagulation dysfunction through the F2/Rho pathway, both of which may be key processes in acute hypoxia‑induced lung injury. The present study provides new insight into the molecular basis of lung injury induced by acute hypoxia. The simultaneous activation of the HMGB1/RAGE/NF‑κB and F2/Rho signaling pathways plays a critical role in hypoxia‑induced inflammatory responses and coagulation abnormalities, and provides a theoretical basis for the development of potential therapeutic strategies.

ISGylation of NF-κBp65 by SCFFBXL19 E3 Ligase Diminishes Endothelial Inflammation

BACKGROUND

NF-κB (nuclear factor kappa B) plays a pivotal role in endothelial cell (EC) inflammation. Protein ISGylation is regulated by E3 ISG15 (interferon-stimulated gene 15) ligases; however, ISGylation of NF-κBp65 and its role in EC functions have not been investigated. Here, we investigate whether p65 is ISGylated and the role of its ISGylation in endothelial functions.

METHODS

In vitro ISGylation assay and EC inflammation were performed. EC-specific transgenic mice were utilized in a murine model of acute lung injury.

RESULTS

We find that NF-κBp65 is ISGylated in resting ECs and that the posttranslational modification is reversible. TNFα (tumor necrosis factor alpha) and endotoxin stimulation of EC reduce p65 ISGylation, promoting its serine phosphorylation through reducing its association with a phosphatase WIP1 (wild-type p53-induced phosphatase 1). Mechanistically, an SCF (Skp1-Cul1-F-box) protein E3 ligase SCFFBXL19 is identified as a new ISG15 E3 ligase that targets and catalyzes ISGylation of p65. Depletion of FBXL19 (F-box and leucine-rich repeat protein 19) increases p65 phosphorylation and EC inflammation, suggesting a negative correlation between p65 ISGylation and phosphorylation. Moreover, EC-specific FBXL19 overexpressing humanized transgenic mice exhibit reduced lung inflammation and severity of experimental acute lung injury.

CONCLUSIONS

Together, our data reveal a new posttranslational modification of p65 catalyzed by a previously unrecognized role of SCFFBXL19 as an ISG15 E3 ligase that modulates EC inflammation.

The effects of flaxseed supplementation on concentration of circulating adipokines in patients with ulcerative colitis

Aim

This study aimed to evaluate the effect of supplementation with ground flaxseed (GF) on the concentrations of adiponectin, resistin, and visfatin in patients with ulcerative colitis (UC).

Background

Inflammatory bowel disease (IBD) is one of the most common gastrointestinal diseases affecting people of all ages. Adipokines secreted from adipose tissue have been shown to play an essential role in the pathogenesis of UC.

Methods

This trial is an open-labeled randomized controlled trial conducted on 70 patients with UC. The patients were randomly divided into two groups: flaxseed and control. The patients in the intervention received 30 g/day flaxseed powder for 12 weeks. Patients' anthropometric, nutritional, and biochemical factors were evaluated at the beginning and end of the intervention period.

Results

Totally, 64 patients (36 men and 28 women) with a mean age of 31.12±9.67 were included in the final analysis. There was no significant difference between the two groups regarding baseline weight and height (P>0.05). After the 12-week intervention, flaxseed supplementation led to a significant reduction in the resistin (-4.85±1.89 vs. -1.10±2.25, P<0.001) and visfatin concentration (-1.33±1.14 vs. -0.53±1.63, P=0.018). Further, we found a significant increase in the adiponectin levels after the GF supplementation (3.49±1.29 vs. -0.35±0.96, P<0.001).

Conclusion

Flaxseed supplementation could exert beneficial effects on adipokine levels in patients with UC.

Loss of SOX18/CLAUDIN5 disrupts the pulmonary endothelial barrier in ventilator-induced lung injury

Mechanical strain contributes to ventilator-induced lung injury (VILI) through multi-factorial and complex mechanisms that remain unresolved. Prevailing evidence suggests that the loss of pulmonary endothelial tight junctions (TJs) plays a critical role. TJs are dynamically regulated by physiologic and hemodynamic forces to stabilize the endothelial barrier. The transcription factor sex-determining region Y-box (SOX)-18 is important in regulating blood vessel development and vascular permeability through its ability to regulate the transcription of Claudin-5, an endothelial TJ protein. Previously, we demonstrated that SOX18 expression is increased by shear stress in the pulmonary endothelium. Therefore, in this study, we investigated how mechanical strain mediated through cyclic stretch affects the SOX18/Claudin-5 regulatory axis. Our data demonstrate that SOX18 and Claudin-5 are downregulated in human lung microvascular endothelial cells (HLMVEC) exposed to cyclic stretch and the mouse lung exposed to high tidal mechanical ventilation. Overexpression of SOX18 reduced the loss of Claudin-5 expression in HLMVEC with cyclic stretch and preserved endothelial barrier function. Additionally, overexpression of Claudin-5 in HLMVEC ameliorated barrier dysfunction in HLMVEC exposed to cyclic stretch, although SOX18 expression was not enhanced. Finally, we found that the targeted overexpression of SOX18 in the pulmonary vasculature preserved Claudin-5 expression in the lungs of mice exposed to HTV. This, in turn reduced lung vascular leak, attenuated inflammatory lung injury, and preserved lung function. Together, these data suggest that enhancing SOX18 expression may prove a useful therapy to treat patients with ventilator-induced lung injury.

Protective Effects of Atractylodis lancea Rhizoma on Lipopolysaccharide-Induced Acute Lung Injury via TLR4/NF-κB and Keap1/Nrf2 Signaling Pathways In Vitro and In Vivo

Acute lung injury (ALI) is a syndrome caused by an excessive inflammatory response characterized by intractable hypoxemia both inside and outside the lung, for which effective therapeutic drugs are lacking. Atractylodis rhizoma, a traditional Chinese medicine, has excellent anti-inflammatory and antiviral properties in addition to protecting the integrity of the cellular barrier. However, few studies of Atractylodis rhizoma for the treatment of ALI have been published, and its mechanism of action remains unclear. In the present study, the chemical composition of the ethanolic extract of Atractylodis rhizoma (EEAR) was initially clarified by high performance liquid chromatography (HPLC), after which it was studied in vivo using a lipopolysaccharide (LPS)-induced ALI rat model. Treatment with EEAR significantly reduced the lung wet/dry (W/D) ratio, neutrophil infiltration, and malondialdehyde (MDA) and myeloperoxidase (MPO) formation, and enhanced superoxide dismutase (SOD) and glutathione (GSH) depletion in rats with ALI, thereby improving lung barrier function and effectively reducing lung injury. In addition, EEAR significantly reduced histopathological changes, decreased the expression of inflammatory factors (such as tumor necrosis factor-α (TNF-α), interleukin-1 beta (IL-1β), inducible nitric oxide synthase (INOS), and cyclooxygenase-2 (COX-2)), and inhibited the activation of the NF-κB signaling pathway, thus reducing inflammation. In addition, EEAR was found to also reduce oxidative stress in ALI by upregulating the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream proteins heme oxygenase-1 (HO-1) and NADPH quinone acceptor oxidoreductase 1 (NQO-1). EEAR also reduced LPS-induced inflammatory factor expression in THP-1 cells in vitro by inhibition of the NF-κB signaling pathway, and reduced damage from lipopolysaccharide (LPS)-induced oxidative stress in THP-1 cells by promoting the expression of Nrf2 and its downstream targets HO-1 and NQO-1, the molecular mechanism of which was consistent with in vivo observations. Therefore, we conclude that EEAR attenuates oxidative stress and inflammatory responses via TLR4/NF-κB and Keap1/Nrf2 signaling pathways to alleviate LPS-induced ALI, suggesting that Atractylodis rhizoma is a potential drug candidate for the treatment of ALI.

Ceramide induces pyroptosis through TXNIP/NLRP3/GSDMD pathway in HUVECs

Background

Pyroptosis of endothelial cells is a new cause of endothelial dysfunction in multiple diseases. Ceramide acts as a potential bioactive mediator of inflammation and increases vascular endothelial permeability in many diseases, whether it can aggravate vascular endothelial injury by inducing cell pyroptosis remains unknown. This study was established to explore the effects of C8-ceramide (C8-Cer) on human umbilical vein vascular endothelial cells (HUVECs) and its possible underlying mechanism.

Methods

HUVECs were exposed to various concentrations of C8-Cer for 12 h, 24 h, 48 h. The cell survival rate was measured using the cell counting kit-8 assay. Western blotting and Real-time polymerase chain reaction (RT-PCR) were used to detect the pyroptosis-releated protein and mRNA expressions, respectively. Caspase-1 activity assay was used to detect caspase-1 activity. Hoechst 33342/propidium iodide double staining and flow cytometry were adopted to measure positive staining of cells. Lactate dehydrogenase release assay and enzyme-linked immunosorbent assay were adopted to measure leakage of cellular contents. FITC method was used to detect the permeability of endothelial cells. ROS fluorescence intensity were detected by flow cytometry.

Results

The viability of HUVECs decreased gradually with the increase in ceramide concentration and time. Ceramide upregulated the expression of thioredoxin interacting protein (TXNIP), NLRP3, GSDMD, GSDMD-NT, caspase-1 and Casp1 p20 at the protein and mRNA level in a dose-dependent manner. It also enhanced the PI uptake in HUVECs and upregulated caspase-1 activity. Moreover, it promoted the release of lactate dehydrogenase, interleukin-1β, and interleukin-18. Meanwhile, we found that ceramide led to increased vascular permeability. The inhibitor of NLRP3 inflammasome assembly, MCC950, was able to disrupt the aforementioned positive loop, thus alleviating vascular endothelial cell damage. Interestingly, inhibition of TXNIP either chemically using verapamil or genetically using small interfering RNA (siRNA) can effectively inhibit ceramide-induced pyroptosis and improved cell permeability. In addition, ceramide stimulated reactive oxygen species (ROS) generation. The pretreatment of antioxidant N-acetylcysteine (NAC), ROS scavenger, blocked the expression of pyroptosis markers induced by C8-cer in HUVECs.

Conclusion

The current study demonstrated that C8-Cer could aggravate vascular endothelial cell damage and increased cell permeability by inducing cell pyroptosis. The results documented that the ROS-dependent TXNIP/NLRP3/GSDMD signalling pathway plays an essential role in the ceramide-induced pyroptosis in HUVECs.

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.

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.

NF-κB-dependent repression of Sox18 transcription factor requires the epigenetic regulators histone deacetylases 1 and 2 in acute lung injury

In acute lung injury (ALI), the NF-κB-mediated downregulation of Sox18 gene expression leads to the disruption of the pulmonary endothelial barrier. Previous studies have suggested that the action of NF-κB as a transcriptional repressor also requires the action of class I histone deacetylases (HDACs). Thus, the purpose of this study was to investigate and further delineate the mechanism of Sox18 repression during lipopolysaccharide (LPS) induced ALI. Using selective inhibitors and specific siRNA-driven depletion of HDACs 1-3 in human lung microvascular endothelial cells (HLMVEC) we were able to demonstrate a critical role for HDACs 1 and 2 in the LPS-mediated repression of Sox18 gene expression and the loss of endothelial monolayer integrity. Moreover, our data demonstrate that HDAC1 associates with a transcription-repressive complex within the NF-κB-binding site of Sox18 promoter. Further, we were able to show that the selective inhibitor of HDAC1, tacedinaline, significantly reduced the endothelial permeability and injury associated with LPS challenge in the mouse lung. Taken together, our data demonstrate, for the first time, that transcription repressors HDACs 1 and 2 are involved in pathological mechanism of ALI and can be considered as therapeutic targets.

Tight Junctions, the Epithelial Barrier, and Toll-like Receptor-4 During Lung Injury

Lung epithelium is constantly exposed to the environment and is critically important for the orchestration of initial responses to infectious organisms, toxins, and allergic stimuli, and maintenance of normal gaseous exchange and pulmonary function. The integrity of lung epithelium, fluid balance, and transport of molecules is dictated by the tight junctions (TJs). The TJs are formed between adjacent cells. We have focused on the topic of the TJ structure and function in lung epithelial cells. This review includes a summary of the last twenty years of literature reports published on the disrupted TJs and epithelial barrier in various lung conditions and expression and regulation of specific TJ proteins against pathogenic stimuli. We discuss the molecular signaling and crosstalk among signaling pathways that control the TJ structure and function. The Toll-like receptor-4 (TLR4) recognizes the pathogen- and damage-associated molecular patterns released during lung injury and inflammation and coordinates cellular responses. The molecular aspects of TLR4 signaling in the context of TJs or the epithelial barrier are not fully known. We describe the current knowledge and possible networking of the TLR4-signaling with cellular and molecular mechanisms of TJs, lung epithelial barrier function, and resistance to treatment strategies.

Mesencephalic astrocyte-derived neurotrophic factor attenuates acute lung injury via inhibiting macrophages' activation

Acute lung injury (ALI) is an urgent respiratory disease without effective treatment. Mesencephalic astrocyte-derived neurotrophic factor (MANF)has been demonstrated to play a suppressive role in some inflammatory conditions. However, the effect of MANF on ALI has not yet been reported. In this study, we collected bronchoalveolar lavage fluid (BALF) from the patients with or without pulmonary inflammation, and used lipopolysaccharide (LPS) to induce mice ALI model. Mono-macrophage-specific MANF knockout (MKO) mice were constructed and recombinant human MANF protein was used to ALI mice. We found that the endogenous MANF protein in both human BALF and mice lung tissues was increased in inflammatory conditions. MANF level in the macrophages of inflammatory lung was higher than that in normal controls in both human and mice. MANF deficiency in macrophages induced lung inflammation and aggravated LPS-induced lung injury. MANF lowered LPS-induced lung injury, inhibited macrophage polarization to M1 functional type. Meanwhile, MANF inhibited-LPS induced activation of NF-κB signal pathway by down regulating phosphorylated p65in lung tissue and macrophages. These results indicate that MANF acts as a suppressor in ALI via negatively regulating NF-κB activation and macrophages polarization, which may be a novel potential target and shed light on ALI therapy.

Beneficial effects of aloperine on inflammation and oxidative stress by suppressing necroptosis in lipopolysaccharide-induced acute lung injury mouse model

RATIONALE

Alveolar epithelial cell death, inflammation, and oxidative stress are typical features of acute lung injury (ALI). Aloperine (Alo), an alkaloid isolated from Sophora alopecuroides, has been reported to display various biological effects, such as anti-inflammatory, immunoregulatory, and anti-oxidant properties. In this study, we investigated the effects and mechanisms of Alo in treating a lipopolysaccharide (LPS)-induced ALI in a murine model.

METHODS

The effects of Alo in LPS-induced ALI were investigated in C57BL/6 mice. The RIPK1 inhibitor (Nec-1) and the RIPK3 inhibitor (GSK'872) were used to evaluate the relationship of necroptosis, NF-κB activation, and PDC subunits in LPS-treated mouse alveolar epithelial cells (MLE-12). Then the effects of Alo on necroptosis, inflammation, and oxidative stress of LPS-stimulated MLE-12 cells were evaluated.

RESULTS

Alo significantly attenuated histopathological lung injuries and reduced lung wet/dry ratio in LPS-induced ALI mice. Alo also remarkedly reduced total protein and neutrophils recruitment in bronchoalveolar lavage fluid of ALI mice. Meanwhile, Alo ameliorated the LPS-induced necroptosis in the lungs of ALI mice. The RIPK3 inhibitor GSK'872, but not the RIPK1 inhibitor Nec-1, reversed LPS-induced p65 phosphorylation and translocation to the nucleus in MLE-12 cells. GSK'872 also reversed the LPS-induced increase in ROS and binding of RIPK3 and PDC subunits in MLE-12 cells. Moreover, Alo down-regulated the levels of p-RIPK1, p-RIPK3, p-MLKL, p-p65, the translocation of p65 to the nucleus, and reduced the expression of IL-6 and IL-8 in LPS-stimulated MLE-12 cells. Alo also inhibited the binding of RIPK3 and PDC-E1α, PDC-E1β, PDC-E2, and PDC-E3 and the ROS production in LPS-treated MLE-12 cells.

CONCLUSION

The present study validated the beneficial effects of Alo on LPS-induced ALI , suggesting Alo may be a new drug candidate against ALI.

Intense light-elicited alveolar type 2-specific circadian PER2 protects from bacterial lung injury via BPIFB1

Circadian amplitude enhancement has the potential to be organ protective but has not been studied in acute lung injury (ALI). Consistent light and dark cycles are crucial for the amplitude regulation of the circadian rhythm protein Period2 (PER2). Housing mice under intense instead of ambient light for 1 wk (light: dark cycle:14h:10h), we demonstrated a robust increase of pulmonary PER2 trough and peak levels, which is consistent with circadian amplitude enhancement. A search for the affected lung cell type suggested alveolar type 2 (ATII) cells as strong candidates for light induction of PER2. A head-to-head comparison of mice with cell-type-specific deletion of Per2 in ATII, endothelial, or myeloid cells uncovered a dramatic phenotype in mice with an ATII-specific deletion of Per2. During Pseudomonas aeruginosa-induced ALI, mice with Per2 deletion in ATII cells showed 0% survival, whereas 85% of control mice survived. Subsequent studies demonstrated that intense light therapy dampened lung inflammation or improved the alveolar barrier function during P. aeruginosa-induced ALI, which was abolished in mice with an ATII-specific deletion of Per2. A genome-wide mRNA array uncovered bactericidal/permeability-increasing fold-containing family B member 1 (BPIFB1) as a downstream target of intense light-elicited ATII-PER2 mediated lung protection. Using the flavonoid and PER2 amplitude enhancer nobiletin, we recapitulated the lung-protective and anti-inflammatory effects of light and BPIFB1, respectively. Together, our studies demonstrate that light-elicited amplitude enhancement of ATII-specific PER2 is a critical control point of inflammatory pathways during bacterial ALI.

SOX18-associated gene signature predicts sepsis outcome

OBJECTIVES

Sepsis is a critical medical condition associated with an high mortality. Currently, there are no reliable diagnostic or prognostic biomarkers to evaluate sepsis outcomes. SRY (sex-determining region on the Y chromosome)-box transcription factor 18 (SOX18) is an endothelial barrier protective protein, and a decreased level of SOX18 expression is involved in disruption of human endothelial cell barrier integrity. Over-expression of SOX18 attenuates the bacterial lipopolysaccharide (LPS)-mediated disruption of the vascular barrier and is associated with favorable prognosis. The utility of SOX18-related genes as biomarkers in sepsis is uncertain.

METHODS

Transcriptomic analysis was used to profile the PBMC samples of patients with sepsis across two Gene Expression Omnibus (GEO) datasets with survival data. An 84-gene signature was derived from discovery datasets that correlated with SOX18 gene expression and sepsis survival.

RESULTS

Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed Th1 and Th2 cell differentiation, Cytokine-cytokine receptor interaction, and T cell receptor signaling pathways as the most significantly enriched KEGG pathways among 84 genes. A severity score based on the gene expression of 84 genes was allocated to each patient. A notable increase was detected in sepsis patients compared to healthy controls in both discovery and validation cohorts. SOX18-associated gene signature discriminated severe cases from mild cases and performed significantly better than both random 84-gene sets from whole genomes or sepsis survival-related genes. Furthermore, we obtained an 18-gene signature from screening these 84 genes in a LASSO model, which performed better in both discovery and validation cohorts.

CONCLUSIONS

Data support SOX18-associated gene signatures as a prognostic biomarker for sepsis.

Integrated Network Pharmacology and Experimental Validation Approach to Investigate the Therapeutic Effects of Capsaicin on Lipopolysaccharide-Induced Acute Lung Injury

An integrated method combining network pharmacology and in vivo experiment was performed to investigate the therapeutic mechanism of capsaicin (Cap) against acute lung injury. The potential key genes and signaling pathways involved in the therapeutic effect of Cap were predicted by the network pharmacology analyses. Additionally, the histological assessment, ELISA, and RT-qPCR were performed to confirm the therapeutic effect and the potential mechanism action involved. Our findings showed that TNF, IL-6, CXCL1, CXCL2, and CXCL10 were part of the top 50 genes. Enrichment analysis revealed that those potential genes were enriched in the TNF signaling pathway and IL-17 signaling pathway. In vivo experiment results showed that Cap alleviated histopathological changes, decreased inflammatory infiltrated cells and inflammatory cytokines, and improved antioxidative enzyme activities in the bronchoalveolar lavage fluid (BALF). Furthermore, Cap treatment effectively downregulated TNF, IL-6, NF-κB, CXCL1, CXCL2, and CXCL10 in lung tissue. Thus, our findings demonstrated that Cap has the therapeutic effect on LPS-induced acute lung injury in neonatal rats via suppression of the TNF signaling pathway and IL-17 signaling pathway.

Fe-Curcumin Nanozyme-Mediated Reactive Oxygen Species Scavenging and Anti-Inflammation for Acute Lung Injury

Pneumonia, such as acute lung injury (ALI), has been a type of lethal disease that is generally caused by uncontrolled inflammatory response and excessive generation of reactive oxygen species (ROS). Herein, we report Fe-curcumin-based nanoparticles (Fe-Cur NPs) with nanozyme functionalities in guiding the intracellular ROS scavenging and meanwhile exhibiting anti-inflammation efficacy for curing ALI. The nanoparticles are noncytotoxic when directing these biological activities. Mechanism studies for the anti-inflammation aspects of Fe-Cur NPs were systematically carried out, in which the infected cells and tissues were alleviated through downregulating levels of several important inflammatory cytokines (such as TNF-α, IL-1β, and IL-6), decreasing the intracellular Ca2+ release, inhibiting NLRP3 inflammasomes, and suppressing NF-κB signaling pathways. In addition, we performed both the intratracheal and intravenous injection of Fe-Cur NPs in mice experiencing ALI and, importantly, found that the accumulation of such nanozymes was enhanced in lung tissue (better than free curcumin drugs), demonstrating its promising therapeutic efficiency in two different administration methods. We showed that the inflammation reduction of Fe-Cur NPs was effective in animal experiments and that ROS scavenging was also effectively achieved in lung tissue. Finally, we revealed that Fe-Cur NPs can decrease the level of macrophage cells (CD11bloF4/80hi) and CD3+CD45+ T cells in mice, which could help suppress the inflammation cytokine storm caused by ALI. Overall, this work has developed the strategy of using Fe-Cur NPs as nanozymes to scavenge intracellular ROS and as an anti-inflammation nanodrugs to synergistically cure ALI, which may serve as a promising therapeutic agent in the clinical treatment of this deadly disease. Fe-Cur NP nanozymes were designed to attenuate ALI by clearing intracellular ROS and alleviating inflammation synergistically. Relevant cytokines, inflammasomes, and signaling pathways were studied.

Lenalidomide attenuates post-inflammation pulmonary fibrosis through blocking NF-κB signaling pathway

Idiopathic pulmonary fibrosis (IPF) is a pathological consequence of interstitial pulmonary diseases, and is characterized by the persistence of fibroblasts and excessive deposition of extracellular matrix (ECM). The etiology of IPF is multifactorial. Although the role of inflammation in fibrogenesis is controversial, it is still recognized as an important component and epiphenomenon of IPF. Stimulus increase production of pro-inflammatory cytokines and activation of NF-κB, which will further promote inflammation response and myofibroblast transition. Lenalidomide is an immunomodulatory drug. Previous studies have revealed its anti-tumor effects through regulating immune response. Here we investigate the effect of lenalidomide on post-inflammation fibrosis. In vitro study revealed that lenalidomide inhibited NF-κB signaling in LPS-induced macrophage, and further attenuated macrophage-induced myofibroblast activation. Meanwhile, lenalidomide could inhibit TGF-β1-induced myofibroblast activation through suppressing TGF-β1 downstream MAPK signaling. In vivo study showed that lenalidomide inhibited pro-inflammatory cytokines TNF-α and IL-6 while enhanced anti-fibrotic cytokines IFN-γ and IL-10 in bleomycin-induced inflammation model, and attenuated pulmonary fibrosis and collagen deposition in the following fibrosis stage. In conclusion, our results demonstrate that lenalidomide possesses potential anti-fibrotic effects through suppressing NF-κB signaling.

A Competitive Endogenous RNA Network Based on Differentially Expressed lncRNA in Lipopolysaccharide-Induced Acute Lung Injury in Mice

Non-coding RNAs have remarkable roles in acute lung injury (ALI) initiation. Nevertheless, the significance of long non-coding RNAs (lncRNAs) in ALI is still unknown. Herein, we purposed to identify potential key genes in ALI and create a competitive endogenous RNA (ceRNA) modulatory network to uncover possible molecular mechanisms that affect lung injury. We generated a lipopolysaccharide-triggered ALI mouse model, whose lung tissue was subjected to RNA sequencing, and then we conducted bioinformatics analysis to select genes showing differential expression (DE) and to build a lncRNA-miRNA (microRNA)- mRNA (messenger RNA) modulatory network. Besides, GO along with KEGG assessments were conducted to identify major biological processes and pathways, respectively, involved in ALI. Then, RT-qPCR assay was employed to verify levels of major RNAs. A protein-protein interaction (PPI) network was created using the Search Tool for the Retrieval of Interacting Genes (STRING) database, and the hub genes were obtained with the Molecular Complex Detection plugin. Finally, a key ceRNA subnetwork was built from major genes and their docking sites. Overall, a total of 8,610 lncRNAs were identified in the normal and LPS groups. Based on the 308 DE lncRNAs [p-value < 0.05, |log2 (fold change) | > 1] and 3,357 DE mRNAs [p-value < 0.05, |log2 (fold change) | > 1], lncRNA-miRNA and miRNA-mRNA pairs were predicted using miRanda. The lncRNA-miRNA-mRNA network was created from 175 lncRNAs, 22 miRNAs, and 209 mRNAs in ALI. The RT-qPCR data keep in step with the RNA sequencing data. GO along with KEGG analyses illustrated that DE mRNAs in this network were mainly bound up with the inflammatory response, developmental process, cell differentiation, cell proliferation, apoptosis, and the NF-kappa B, PI3K-Akt, HIF-1, MAPK, Jak-STAT, and Notch signaling pathways. A PPI network on the basis of the 209 genes was established, and three hub genes (Nkx2-1, Tbx2, and Atf5) were obtained from the network. Additionally, a lncRNA-miRNA-hub gene subnetwork was built from 15 lncRNAs, 3 miRNAs, and 3 mRNAs. Herein, novel ideas are presented to expand our knowledge on the regulation mechanisms of lncRNA-related ceRNAs in the pathogenesis of ALI.

Terbutaline attenuates LPS-induced injury of pulmonary microvascular endothelial cells by cAMP/Epac signaling

Acute lung injury (ALI), characterized by an acute onset of severe hypoxemia, is a common and devastating syndrome usually triggered by lipopolysaccharide (LPS) infection from bacteria. This study is intended to explore whether terbutaline can alleviate LPS-induced human pulmonary microvascular endothelial cell (HPMVEC) injury through cAMP/Epac signaling. LPS was utilized to induce ALI in HPMVECs, and after exposure of LPS-induced HPMVECs to terbutaline, the cellular functions including cell viability and apoptosis were measured by cell counting kit-8 and terminal deoxynucleotidyl transferase dUTP nick-end labeling. The protein expression related to cAMP/Epac signaling, apoptosis, and that of tight junction and inflammatory factors were evaluated at the same time. The effects of terbutaline on cellular functions were confirmed again after the addition of antagonists of cAMP and Epac, respectively. The levels of both cAMP and Epac reduced by LPS was concentration-dependently increased by terbutaline. The apoptosis and endothelial cell permeability damage of LPS-induced HPMVECs were enhanced after the addition of KT-5720 and ESI-09. The beneficial effects of terbutaline on alleviating the inflammation and apoptosis in HPMVECs injured by LPS are mediated by cAMP/Epac signaling, and this evidence would demonstrate the potential of terbutaline in the treatment of ALI.

Identification of significant alteration genes, pathways and TFs induced by LPS in ARDS via bioinformatical analysis

Background and aims

Acute respiratory distress syndrome (ARDS) or acute lung injury (ALI) is one of the most common acute thoracopathy with complicated pathogenesis in ICU. The study is to explore the differentially expressed genes (DEGs) in the lung tissue and underlying altering mechanisms in ARDS.

Methods

Gene expression profiles of GSE2411 and GSE130936 were available from GEO database, both of them included in GPL339. Then, an integrated analysis of these genes was performed, including gene ontology (GO) and KEGG pathway enrichment analysis in DAVID database, protein–protein interaction (PPI) network construction evaluated by the online database STRING, Transcription Factors (TFs) forecasting based on the Cytoscape plugin iRegulon, and their expression in varied organs in The Human Protein Atlas.

Results

A total of 39 differential expressed genes were screened from the two datasets, including 39 up-regulated genes and 0 down-regulated genes. The up-regulated genes were mainly enriched in the biological process, such as immune system process, innate immune response, inflammatory response, and also involved in some signal pathways, including cytokine–cytokine receptor interaction, Salmonella infection, Legionellosis, Chemokine, and Toll-like receptor signal pathway with an integrated analysis. GBP2, IFIT2 and IFIT3 were identified as hub genes in the lung by PPI network analysis with MCODE plug-in, as well as GO and KEGG re-enrichment. All of the three hub genes were regulated by the predictive common TFs, including STAT1, E2F1, IRF1, IRF2, and IRF9.

Conclusions

This study implied that hub gene GBP2, IFIT2 and IFIT3, which might be regulated by STAT1, E2F1, IRF1, IRF2, or IRF9, played significant roles in ARDS. They could be potential diagnostic or therapeutic targets for ARDS patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06578-7.

hucMSC Conditioned Medium Ameliorate Lipopolysaccharide-Induced Acute Lung Injury by Suppressing Oxidative Stress and Inflammation via Nrf2/NF-κB Signaling Pathway

Acute lung injury (ALI) is a common clinical syndrome in the cardiac intensive care unit with a high mortality rate. Inflammation and oxidative stress have been reported to play a crucial role in the development of ALI. Previous studies have shown that human umbilical cord mesenchymal stem cells (hucMSCs) have anti-inflammatory and antioxidative effects in various diseases. However, the anti-inflammatory and antioxidative effects of the hucMSC conditioned medium (CM) on LPS-induced ALI remain unclear. Therefore, in this study, we assessed whether the hucMSC conditioned medium could attenuate LPS-induced ALI and the underlying mechanisms. Mice were randomly divided into four groups: the control group, PBS group, LPS+PBS group, and LPS+CM group. The lung histopathology and bronchoalveolar lavage fluid (BALF) were analyzed after intervention. The Nrf2/NF-κB signaling pathway and its downstream target genes were tested, and the cytokines and growth factors in CM were also measured. The results showed that CM significantly attenuated the histological alterations; decreased the wet/dry weight ratio; reduced the levels of MPO, MDA and ROS; increased SOD and GSH activity; and downregulated the level of proinflammatory cytokines such as IL-1β, IL-6, and TNF-α. Furthermore, CM promoted the expression of Nrf2 and its target genes NQ01, HO-1, and GCLC and inhibited the expression of NF-κB and its target genes IL-6, IL-1β, and TNF-α. These effects may be closely related to the large amounts of cytokines and growth factors in the CM. In conclusion, our results demonstrated that CM could attenuate LPS-induced ALI, probably due to inhibition of inflammation and oxidative stress via the Nrf2/NF-κB signaling pathway.

MIR3142HG promotes lipopolysaccharide-induced acute lung injury by regulating miR-450b-5p/HMGB1 axis

The present study aimed to evaluate the potential roles of MIR3142HG, a novel long non-coding RNA (lncRNA) in lipopolysaccharide (LPS)-induced acute lung injury (ALI). ALI was simulated by the treatment of LPS in human pulmonary microvascular endothelial cells (HPMECs). The expression of MIR3142HG, miR-450b-5p and high-mobility group box 1 (HMGB1) was determined by real-time PCR and western blotting. Functional analysis was performed through the assessment of cell viability, apoptosis and the production of proinflammatory cytokines. The interactions among MIR3142HG, miR-450b-5p and HMGB1 were analyzed by bioinformatics methods, dual-luciferase reporter and RNA pull-down assays. Using gain- and loss-of-function approaches, the in vitro functions of MIR3142HG and miR-450b-5p were subsequently assessed. MIR3142HG expression was upregulated, while miR-450b-5p was decreased in LPS-treated HPMECs. MIR3142HG knockdown protected against ALI induced by LPS through alleviating the apoptosis and inflammation of HPMECs. MIR3142HG impaired miR-450b-5p-mediated inhibition of HMGB1. Besides, the effects of MIR3142HG silencing could be alleviated by miR-4262 inhibition or HMGB1 overexpression. MIR3142HG mediated LPS-induced injury of HPMECs by targeting miR-450b-5p/HMGB1, suggesting that MIR3142HG might serve as a therapeutic potential for the treatment of ALI.

3-O-trans-caffeoyloleanolic acid improves acute lung injury via anti-inflammation and antioxidative stress-involved PI3K/AKT pathway

3-O-trans-caffeoyloleanolic acid (COA) is a pentacyclic triterpenoid compound, with significant anti-inflammatory effects. In this study, we report the protective effects of COA on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and explored its mechanism of action. LPS was used to construct in vivo mouse ALI models to observe the effects of COA pretreatment on lung pathology, inflammation, and oxidative stress. In vitro, mouse alveolar macrophages MH-S cells were cultured and stimulated with LPS to investigate the effects of COA pretreatment on inflammation and oxidative stress. Western blotting was used to investigate the expression of iNOS, TLR4, p-p65, p-AKT, and p-PI3K from in vivo and in vitro samples. The results showed that COA significantly improved lung injury, inhibited neutrophil infiltration, prevented macrophage infiltration, inhibited the release of inflammatory factors, reduced oxidative stress, and down-regulated the expression of iNOS, TLR4, p-p65, p-AKT, and p-PI3K in ALI mice caused by LPS. In vitro, COA inhibited the release of inflammatory factors, reduced oxidative stress, and down-regulated the expression of iNOS, TLR4, p-p65, p-AKT, and p-PI3K in MH-S cells stimulated with LPS. Of interest, the protective effects of COA were significantly attenuated in MH-S cells pretreated with the PI3K phosphopeptide activator 740Y-P with no effect on TLR4 expression observed. Taken together, these findings confirm the protective effects of COA on ALI. We further demonstrate that the anti-inflammation and antioxidant effects of COA are mediated through its effects on PI3K/AKT and potentially TLR4.

Heteromeric TRP Channels in Lung Inflammation

Activation of Transient Receptor Potential (TRP) channels can disrupt endothelial barrier function, as their mediated Ca²⁺ influx activates the CaM (calmodulin)/MLCK (myosin light chain kinase)-signaling pathway, and thereby rearranges the cytoskeleton, increases endothelial permeability and thus can facilitate activation of inflammatory cells and formation of pulmonary edema. Interestingly, TRP channel subunits can build heterotetramers, whereas heteromeric TRPC1/4, TRPC3/6 and TRPV1/4 are expressed in the lung endothelium and could be targeted as a protective strategy to reduce endothelial permeability in pulmonary inflammation. An update on TRP heteromers and their role in lung inflammation will be provided with this review.

MicroRNA‑129 plays a protective role in sepsis‑induced acute lung injury through the suppression of pulmonary inflammation via the modulation of the TAK1/NF‑κB pathway

Excessive inflammatory response and apoptosis play key roles in the pathogenic mechanisms of sepsis-induced acute lung injury (ALI); however, the molecular pathways linked to ALI pathogenesis remain unclear. Recently, microRNAs (miRNAs/miRs) have emerged as important regulators of inflammation and apoptosis in sepsis-induced ALI; however, the exact regulatory mechanisms of miRNAs remain poorly understood. In the present study, the gene microarray dataset GSE133733 obtained from the Gene Expression Omnibus database was analyzed and a total of 38 differentially regulated miRNAs were identified, including 17 upregulated miRNAs and 21 downregulated miRNAs, in mice with lipopolysaccharide (LPS)-induced ALI, in comparison to the normal control mice. miR-129 was found to be the most significant miRNA, among the identified miRNAs. The upregulation of miR-129 markedly alleviated LPS-induced lung injury, as indicated by the decrease in lung permeability in and the wet-to-dry lung weight ratio, as well as the improved survival rate of mice with ALI administered miR-129 mimic. Moreover, the upregulation of miR-129 reduced pulmonary inflammation and apoptosis in mice with ALI. Of note, transforming growth factor activated kinase-1 (TAK1), a well-known regulator of the nuclear factor-κB (NF-κB) pathway, was directly targeted by miR-129 in RAW 264.7 cells. More importantly, miR-129 upregulation impeded the LPS-induced activation of the TAK1/NF-κB signaling pathway, as illustrated by the suppression of the nuclear phosphorylated-p65, p-IκB-α and p-IKKβ expression levels. Collectively, the findings of the present study indicate that miR-129 protects mice against sepsis-induced ALI by suppressing pulmonary inflammation and apoptosis through the regulation of the TAK1/NF-κB signaling pathway. This introduces the basis for future research concerning the application of miR-129 and its targets for the treatment of ALI.

SOX18 enhances the proliferation and migration of airway smooth muscle cells induced by tumor necrosis factor-α via the regulation of Notch1 signaling

Childhood asthma is a frequent chronic disease of pediatric populations. The excessive proliferation and migration of airway smooth muscle cells contribute to airway remodeling during asthma pathogenesis. Sex-determining region on the Y chromosome-related high mobility group box 18 (SOX18) has been reported to be over-expressed in asthma. However, whether SOX18 plays a role in modulating the airway remodeling of asthma is not fully understood. The purposes of this work were to assess the potential role of SOX18 in modulating airway remodeling using tumor necrosis factor-α (TNF-α)-stimulated airway smooth muscle cells in vitro. Our results showed that SOX18 expression was increased following TNF-α stimulation in airway smooth muscle cells. The silencing of SOX18 markedly prohibited the proliferation and migration of airway smooth muscle cells induced by TNF-α, whilst the over-expression of SOX18 produced the opposite effects. Further investigation revealed that SOX18 promoted the expression of Notch1, and enhanced the activation of Notch1 signaling in airway smooth muscle cells stimulated by TNF-α. The inhibition of Notch1 markedly diminished SOX18-over-expression-evoked promotion effects on TNF-α-induced proliferation and migration of airway smooth muscle cells. In addition, the reactivation of Notch1 signaling markedly reversed the SOX18-silencing-induced suppressive effect on the TNF-α-induced proliferation and the migration of airway smooth muscle cells. In summary, the findings of this work demonstrate that SOX18 regulates the proliferation and migration of airway smooth muscle cells induced by TNF-α via the modulation of Notch1 signaling. This study indicates a potential role for SOX18 in promoting airway remodeling during asthma pathogenesis.

Inhibition of Class IIa HDACs improves endothelial barrier function in endotoxin-induced acute lung injury

Acute lung injury (ALI) is an acute inflammatory process arises from a wide range of lung insults. A major cause of ALI is dysfunction of the pulmonary vascular endothelial barrier but the mechanisms involved are incompletely understood. The therapeutic potential of histone deacetylase (HDAC) inhibitors for the treatment of cardiovascular and inflammatory diseases is increasingly apparent, but the mechanisms by which HDACs regulate pulmonary vascular barrier function remain to be resolved. We found that specific Class IIa HDACs inhibitor, TMP269, significantly attenuated the lipopolysaccharide (LPS)-induced human lung microvascular endothelial cells (HLMVEC) barrier compromise in vitro and improved vascular barrier integrity and lung function in murine model of ALI in vivo. TMP269 decreased LPS-induced myosin light chain phosphorylation suggesting the role for Class IIa HDACs in LPS-induced cytoskeleton reorganization. TMP269 did not affect microtubule structure and tubulin acetylation in contrast to the HDAC6-specific inhibitor, Tubastatin A suggesting that Class IIa HDACs and HDAC6 (Class IIb) regulate endothelial cytoskeleton and permeability via different mechanisms. Furthermore, LPS increased the expression of ArgBP2 which has recently been attributed to HDAC-mediated activation of Rho. Depletion of ArgBP2 abolished the ability of LPS to disrupt barrier function in HLMVEC and both TMP269 and Tubastatin A decreased the level of ArgBP2 expression after LPS stimulation suggesting that both Class IIa and IIb HDACs regulate endothelial permeability via ArgBP2-dependent mechanism. Collectively, our data strongly suggest that Class IIa HDACs are involved in LPS-induced ALI in vitro and in vivo via specific mechanism which involved contractile responses, but not microtubule reorganization.

Pellino1 promoted inflammation in lung injury model of sepsis by TRAF6/ NF-κB signal pathway

Background

This study was designed to investigate the role of Pellino1 in lung injury model of sepsis and its anti-inflammation mechanism.

Method:

C57BL/6 male mice (6–7 weeks old) and Pellino1^−/− male mice were subjected to laparotomy followed by extracorporeal cecum mobilization and ligation. THP-1 cells were treated with 500 ng/ml of LPS for 4 h. Both mRNA and protein expression of Pellino1 was increased at time dependence in lung tissue of lung injury model of sepsis mice. Knockout of Pellino1 attenuated lung injury and inhibited inflammation of sepsis mice. While Pellino1 protein enhanced lung injury and increased inflammation of sepsis mice. Pellino1 promoted inflammation in in vitro model of lung injury by TRAF6/ NF-κB signal pathway.

Result

TRAF6 inhibitor attenuated the effects of Pellino1 on inflammation and lung injury in mice of sepsis. Similarly, NF-κB inhibitor also suppressed the effects of Pellino1 on inflammation and lung injury in mice of sepsis. The activation of TRAF6 or induction of NF-κB attenuated the effects of Pellino1 on inflammation in in vitro model of sepsis. The inhibition of TRAF6 or suppression of NF-κB reduced the effects of Pellino1 on inflammation in in vitro model of sepsis.

Conclusions

These results suggested that Pellino1 promoted inflammation in lung injury model of sepsis by TRAF6/ NF-κB signal pathway.

Resveratrol alleviates bleomycin-induced pulmonary fibrosis via suppressing HIF-1α and NF-κB expression

The absence of a gold standard for treating pulmonary fibrosis makes its management challenging. We established a rat model to study the effect of resveratrol (Res) on bleomycin-induced pulmonary fibrosis. Rats were randomly divided into control, model, low-Res, middle-Res, high-Res, and dexamethasone groups and treated with various concentrations of these drugs. Rats showed typical features of pulmonary fibrosis; i.e., alveolitis, fibrous hyperplasia, and fibrosis on days 7, 14, and 28, respectively. Expression of HIF-1α and NF-κB was higher in the middle-Res, high-Res, and dexamethasone groups than in the control group, but was less than that in the model and low Res groups. We conclude that different levels of HIF-1α and NF-κB expression at different stages of pulmonary fibrosis in rats is positively correlated with the disease severity. Furthermore, resveratrol alleviates bleomycin-induced pulmonary fibrosis by suppressing HIF-1α and NF-κB expression, indicating its potential as a promising therapeutic drug candidate.

Oxycodone attenuates vascular leak and lung inflammation in a clinically relevant two-hit rat model of acute lung injury

BACKGROUND

Oxycodone is a synthetic opioid receptor agonist that exerts antinociceptive activity via κ-, μ- and δ-opioid receptors (KOR, MOR and DOR, respectively). Activation of MOR has been reported to provide protection against acute lung injury (ALI). We hypothesized that pretreatment with oxycodone would attenuate lung injury at the level of alveolar tight junctions (TJs) and aquaporins (AQPs) and investigated this possibility in a two-hit model of ALI induced by lipopolysaccharide (LPS) and mechanical ventilation (MV).

METHOD

Male Sprague Dawley rats and A59 cells were divided into 6 groups: the control group, ALI group, oxycodone-pretreated group, and oxycodone/κ-, μ-, or δ-opioid receptor antagonist-pretreated groups. The rats were pretreated with oxycodone 30 min before intravenous injection of LPS and then allowed to recover for 24 h prior to MV, establishing a two-hit model of ALI. The cells were similarly treated with oxycodone (with or without antagonists) 30 min after exposure to lipopolysaccharide. The cells were cyclically stretched 24 h later to mirror the in vivo MV protocol.

RESULTS

Oxycodone alleviated the histological lung changes in the rats with ALI and decreased pulmonary microvascular permeability both in vivo and in vitro. Oxycodone upregulated the expression of claudin-5, ZO-1, AQP1, and AQP5 but downregulated the expression of TNF-α, IL-1β, TLR4, NF-κB, MMP9, and caspase-3 and suppressed endothelial apoptosis in vivo and in vitro. These protective effects of oxycodone were partly eliminated by KOR and MOR antagonists but not by DOR antagonists.

CONCLUSION

Oxycodone pretreatment appears to act via κ- and μ-opioid receptors to ameliorate LPS- and MV-induced lung injury by suppressing inflammation and apoptosis, and this protective effect might be mediated through the inhibition of the TLR4/NF-κB pathways.

Serine protease inhibitor MDSPI16 ameliorates LPS-induced acute lung injury through its anti-inflammatory activity

A previous study described a novel serine protease inhibitor 16 from Musca domestica (MDSPI16), which inhibited the elastase and chymotrypsin. It also exhibited a potential anti-inflammatory activity for acute lung injury (ALI), while its effects on ALI are yet to be elucidated. The present study aimed to investigate the effects and the underlying mechanisms of MDSPI16 on lipopolysaccharide (LPS)-challenged mice and bone marrow neutrophils. The ALI model based on the results of LPS-induced mice demonstrated that MDSPI16 markedly reduced the infiltration of inflammatory cells, protein exudation in lung tissues, and downregulated the level of interleukin-6 (IL-6), IL-1β and tumor necrosis factor-α (TNF-α). Furthermore, the LPS-stimulated mouse bone marrow neutrophils model was employed to determine the role of MDSPI16. The cytokine levels were quantified by both the enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR). Consequently, the expression of IL-6, IL-1β, and TNF-α was found to be inhibited by MDSPI16 in a dose-dependent manner. Moreover, MDSPI16 also inhibited the mouse neutrophils nuclear factor-κB (NF-κB) signaling pathway, c-Jun N-terminal kinase (JNK) signaling pathway, ERK1/2 and AP-1 signaling pathway in addition to the expression of iNOS and COX-2 proteins, which in turn, might alleviate the release of pro-inflammatory cytokines during ALI. Therefore, MDSPI16 could be proposed as a potential and novel drug therapy for ALI.

Autophagy Augmentation to Alleviate Immune Response Dysfunction, and Resolve Respiratory and COVID-19 Exacerbations

The preservation of cellular homeostasis requires the synthesis of new proteins (proteostasis) and organelles, and the effective removal of misfolded or impaired proteins and cellular debris. This cellular homeostasis involves two key proteostasis mechanisms, the ubiquitin proteasome system and the autophagy–lysosome pathway. These catabolic pathways have been known to be involved in respiratory exacerbations and the pathogenesis of various lung diseases, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), idiopathic pulmonary fibrosis (IPF), acute lung injury (ALI), acute respiratory distress syndrome (ARDS), and coronavirus disease-2019 (COVID-19). Briefly, proteostasis and autophagy processes are known to decline over time with age, cigarette or biomass smoke exposure, and/or influenced by underlying genetic factors, resulting in the accumulation of misfolded proteins and cellular debris, elevating apoptosis and cellular senescence, and initiating the pathogenesis of acute or chronic lung disease. Moreover, autophagic dysfunction results in an impaired microbial clearance, post-bacterial and/or viral infection(s) which contribute to the initiation of acute and recurrent respiratory exacerbations as well as the progression of chronic obstructive and restrictive lung diseases. In addition, the autophagic dysfunction-mediated cystic fibrosis transmembrane conductance regulator (CFTR) immune response impairment further exacerbates the lung disease. Recent studies demonstrate the therapeutic potential of novel autophagy augmentation strategies, in alleviating the pathogenesis of chronic obstructive or restrictive lung diseases and exacerbations such as those commonly seen in COPD, CF, ALI/ARDS and COVID-19.

Direct Extracellular NAMPT Involvement in Pulmonary Hypertension and Vascular Remodeling. Transcriptional Regulation by SOX and HIF-2α

We previously demonstrated involvement of NAMPT (nicotinamide phosphoribosyltransferase) in pulmonary arterial hypertension (PAH) and now examine NAMPT regulation and extracellular NAMPT's (eNAMPT's) role in PAH vascular remodeling. NAMPT transcription and protein expression in human lung endothelial cells were assessed in response to PAH-relevant stimuli (PDGF [platelet-derived growth factor], VEGF [vascular endothelial growth factor], TGF-β1 [transforming growth factor-β1], and hypoxia). Endothelial-to-mesenchymal transition was detected by SNAI1 (snail family transcriptional repressor 1) and PECAM1 (platelet endothelial cell adhesion molecule 1) immunofluorescence. An eNAMPT-neutralizing polyclonal antibody was tested in a PAH model of monocrotaline challenge in rats. Plasma eNAMPT concentrations, significantly increased in patients with idiopathic pulmonary arterial hypertension, were highly correlated with indices of PAH severity. eNAMPT increased endothelial-to-mesenchymal transition, and each PAH stimulus significantly increased endothelial cell NAMPT promoter activity involving transcription factors STAT5 (signal transducer and activator of transcription 5), SOX18 (SRY-box transcription factor 18), and SOX17 (SRY-box transcription factor 17), a PAH candidate gene newly defined by genome-wide association study. The hypoxia-induced transcription factor HIF-2α (hypoxia-inducible factor-2α) also potently regulated NAMPT promoter activity, and HIF-2α binding sites were identified between -628 bp and -328 bp. The PHD2 (prolyl hydroxylase domain-containing protein 2) inhibitor FG-4592 significantly increased NAMPT promoter activity and protein expression in an HIF-2α-dependent manner. Finally, the eNAMPT-neutralizing polyclonal antibody significantly reduced monocrotaline-induced vascular remodeling, PAH hemodynamic alterations, and NF-κB activation. eNAMPT is a novel and attractive therapeutic target essential to PAH vascular remodeling.

Impact of Bacterial Toxins in the Lungs

Bacterial toxins play a key role in the pathogenesis of lung disease. Based on their structural and functional properties, they employ various strategies to modulate lung barrier function and to impair host defense in order to promote infection. Although in general, these toxins target common cellular signaling pathways and host compartments, toxin- and cell-specific effects have also been reported. Toxins can affect resident pulmonary cells involved in alveolar fluid clearance (AFC) and barrier function through impairing vectorial Na⁺ transport and through cytoskeletal collapse, as such, destroying cell-cell adhesions. The resulting loss of alveolar-capillary barrier integrity and fluid clearance capacity will induce capillary leak and foster edema formation, which will in turn impair gas exchange and endanger the survival of the host. Toxins modulate or neutralize protective host cell mechanisms of both the innate and adaptive immunity response during chronic infection. In particular, toxins can either recruit or kill central players of the lung's innate immune responses to pathogenic attacks, i.e., alveolar macrophages (AMs) and neutrophils. Pulmonary disorders resulting from these toxin actions include, e.g., acute lung injury (ALI), the acute respiratory syndrome (ARDS), and severe pneumonia. When acute infection converts to persistence, i.e., colonization and chronic infection, lung diseases, such as bronchitis, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF) can arise. The aim of this review is to discuss the impact of bacterial toxins in the lungs and the resulting outcomes for pathogenesis, their roles in promoting bacterial dissemination, and bacterial survival in disease progression.

Molecular adaptations of the blood-brain barrier promote stress resilience vs. depression

Preclinical and clinical studies suggest that inflammation and vascular dysfunction contribute to the pathogenesis of major depressive disorder (MDD). Chronic social stress alters blood-brain barrier (BBB) integrity through loss of tight junction protein claudin-5 (cldn5) in male mice, promoting passage of circulating proinflammatory cytokines and depression-like behaviors. This effect is prominent within the nucleus accumbens, a brain region associated with mood regulation; however, the mechanisms involved are unclear. Moreover, compensatory responses leading to proper behavioral strategies and active resilience are unknown. Here we identify active molecular changes within the BBB associated with stress resilience that might serve a protective role for the neurovasculature. We also confirm the relevance of such changes to human depression and antidepressant treatment. We show that permissive epigenetic regulation of cldn5 expression and low endothelium expression of repressive cldn5-related transcription factor foxo1 are associated with stress resilience. Region- and endothelial cell-specific whole transcriptomic analyses revealed molecular signatures associated with stress vulnerability vs. resilience. We identified proinflammatory TNFα/NFκB signaling and hdac1 as mediators of stress susceptibility. Pharmacological inhibition of stress-induced increase in hdac1 activity rescued cldn5 expression in the NAc and promoted resilience. Importantly, we confirmed changes in HDAC1 expression in the NAc of depressed patients without antidepressant treatment in line with CLDN5 loss. Conversely, many of these deleterious CLDN5-related molecular changes were reduced in postmortem NAc from antidepressant-treated subjects. These findings reinforce the importance of considering stress-induced neurovascular pathology in depression and provide therapeutic targets to treat this mood disorder and promote resilience.

TRPV4 Protects the Lung from Bacterial Pneumonia via MAPK Molecular Pathway Switching

Mechanical cell-matrix interactions can drive the innate immune responses to infection; however, the molecular underpinnings of these responses remain elusive. This study was undertaken to understand the molecular mechanism by which the mechanosensitive cation channel, transient receptor potential vanilloid 4 (TRPV4), alters the in vivo response to lung infection. For the first time, to our knowledge, we show that TRPV4 protects the lung from injury upon intratracheal Pseudomonas aeruginosa in mice. TRPV4 functions to enhance macrophage bacterial clearance and downregulate proinflammatory cytokine secretion. TRPV4 mediates these effects through a novel mechanism of molecular switching of LPS signaling from predominant activation of the MAPK, JNK, to that of p38. This is accomplished through the activation of the master regulator of inflammation, dual-specificity phosphatase 1. Further, TRPV4's modulation of the LPS signal is mechanosensitive in that both upstream activation of p38 and its downstream biological consequences depend on pathophysiological range extracellular matrix stiffness. We further show the importance of TRPV4 on LPS-induced activation of macrophages from healthy human controls. These data are the first, to our knowledge, to demonstrate new roles for macrophage TRPV4 in regulating innate immunity in a mechanosensitive manner through the modulation of dual-specificity phosphatase 1 expression to mediate MAPK activation switching.

Irisin alleviates pulmonary epithelial barrier dysfunction in sepsis-induced acute lung injury via activation of AMPK/SIRT1 pathways

OBJECTIVE

Alveolar epithelial barrier dysfunction in response to inflammatory reaction contributes to pulmonary edema in acute lung injury(ALI).Irisin,a newly-found myokine,exerts the anti-inflammatory effects. This study aims to investigate the protective effects of irisin on lipopolysaccharide (LPS)-induced ALIin vivo and in vitro, and to explore its underlying mechanism.

METHODS

Male SD rats and A549 cells were divided into 4 groups: control group, LPS group, Irisin pretreated group, and Irisin/Compound C(a special inhibitor of AMPK)-treated group. The ALI model was established by intravenous injection of LPS in rats, and LPS challenge in A549 cells. Pulmonary specimens were harvested for microscopic examination of the pathological changes, and the expression of AMPK,SIRT1,NF-κB, p66Shc and caspase-3 in lung tissues. The pulmonary permeability were examined by wet/dry lung weight ratio(W/D) and lung permeability index(LPI). The apoptotic index, and the expression of tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), monocyte chemoattractant activating protein-1 (MCP-1), tight junctions (occludin,ZO-1) were determined both in lung tissue and A549 cells.

RESULTS

Irisin alleviated lung histological changes and decreased pulmonary microvascular permeability in LPS-induced rats. Irisin up-regulated the expression of occludin, ZO-1,AMPK,SIRT1, down-regulated the expression of TNF-α,IL-1β,MCP-1,NF-κB, p66Shc caspase-3, and decreased the apoptotic index in LPS-induced rats and A549 cells. All these protective effects of irisin could be reversed by Compound C.

CONCLUSION

Irisin improved LPS-induced alveolar epithelial barrier dysfunction via suppressing inflammation and apoptosis, and this protective effect might be mediated by activating AMPK/SIRT1 pathways.

PIM1 inhibitor SMI-4a attenuated lipopolysaccharide-induced acute lung injury through suppressing macrophage inflammatory responses via modulating p65 phosphorylation

PIM kinase is involved in the cellular processes of growth, differentiation and apoptosis. However, the role of PIM1 in lipopolysaccharide (LPS)-induced acute lung injury (ALI) remains largely unknown. A trend of PIM1 in the lung tissue of LPS-induced ALI at different time points was detected. Histology, wet/dry (W/D) ratio, inflammatory cells in the bronchoalveolar lavage fluid (BALF) and survival rate analyses were performed when mice received the PIM1 inhibitor SMI-4a intratracheally 3 h before LPS administration. Cytokine production in vivo and in vitro was measured after SMI-4a pretreatment. NF-κB subunit p65 expression in nuclei and phosphorylation at Ser276 in lung tissues or cells were detected by Western blot analysis. The results showed that PIM1 mRNA and protein were upregulated in the lung tissue of LPS-induced ALI. The PIM1 inhibitor SMI-4a markedly improved the survival rate after lethal LPS administration, reduced the severity of lung edema, attenuated the histologic injuries of the lung tissue and reduced the counts of infiltrated inflammatory cells in the BALF. The PIM1 inhibitor SMI-4a suppressed the production of cytokines in LPS-treated RAW264.7 cell supernatants and BALF. Furthermore, LPS administration upregulated the levels of nuclear p65 and phosphorylated p65 (p-p65) at Ser276, whereas pretreatment with the PIM1 inhibitor SMI-4a reduced p65 upregulation in the nucleus and p-p65 at Ser276. Taken together, these data indicate that the PIM1 inhibitor SMI-4a may serve as a promising therapeutic strategy for LPS-induced ALI by suppressing macrophage production of cytokines via a reduction of p65 activities.

Transfection of Sox11 plasmid alleviates ventilator-induced lung injury via Sox11 and FAK

Background Ventilator-induced lung injury (VILI) is the most common complication in the mechanical ventilation in clinic. The pathogenesis of VILI has not been well understood. The SRY related High Mobility Group box group-F family member 11(Sox11) is a protein associated with lung development. The focal adhesion kinase(FAK) is a cytoplasmic tyrosine kinase and is regulated by Sox11. The present study, therefore, was undertaken to explore the potential role of Sox11 and FAK in VILI. Methods High volume mechanical ventilation(HMV) was used to establish mouse VILI model under anesthesia. The lung injury was evaluated by analyzing the lung weight, bronchoalveolar lavage fluid, histopathological changes and apoptosis of the lung. The Sox11 and FAK expressions in the lung were investigated by real-time qPCR, western blot and immunohistochemistry analysis. Results HMV induced VILI simultaneously companied with decreased expressions of Sox11 and FAK in alveolar epithelial and interstitial cells either in gene and protein levels. Transfection of Sox11 plasmid significantly upregulated expressions of Sox11 and FAK in gene and protein levels in the lung and particularly effectively alleviated VILI. Furthermore, FAK antagonism by PF562271(FAK antagonist) blocked the alleviating effect of Sox11 plasmid transfection on the VILI. Conclusion The dysregulation in the Sox11 and FAK after HMV play an important role in the pathogenesis of VILI, and facilitating the activity of Sox11and FAK might be an effective target and potential option in the prevention and treatment of VILI in clinic.