LPS-induced Acute Lung Injury In Mice Research Articles

S100A9 exacerbates sepsis-induced acute lung injury via the IL17-NFκB-caspase-3 signaling pathway

BackgroundSepsis-induced acute lung injury (ALI) is associated with considerable morbidity and mortality in critically ill patients. S100A9, a key endothelial injury factor, is markedly upregulated in sepsis-induced ALI; however, its specific mechanism of action has not been fully elucidated. MethodsThe Gene Expression Omnibus database transcriptome data for sepsis-induced ALI were used to screen for key differentially expressed genes (DEGs). Using bioinformatics analysis methods such as Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and protein-protein interaction network analyses, the pathogenesis of sepsis-induced ALI was revealed. Intratracheal infusion of lipopolysaccharide (LPS, 10 mg/kg) induced ALI in wild-type (WT) and S100A9 knockout mice. Multiomics analyses (transcriptomics and proteomics) were performed to investigate the potential mechanisms by which S100A9 exacerbates acute lung damage. Hematoxylin-eosin, Giemsa, and TUNEL staining were used to evaluate lung injury and cell apoptosis. LPS (10 μg/mL)-induced murine lung epithelial MLE-12 cells were utilized to mimic ALI and were modulated by S100A9 lentiviral transfection. The impact of S100A9 on cell apoptosis and inflammatory responses were identified using flow cytometry and PCR. The expression of interleukin (IL)-17–nuclear factor kappa B (NFκB)–caspase-3 signaling components was identified using western blotting. ResultsSix common DEGs (S100A9, S100A8, IFITM6, SAA3, CD177, and MMP9) were identified in the six datasets related to ALI in sepsis. Compared to WT sepsis mice, S100A9 knockout significantly alleviated LPS-induced ALI in mice, with reduced lung structural damage and inflammatory exudation, decreased exfoliated cell and protein content in the lung lavage fluid, and reduced apoptosis and necrosis of pulmonary epithelial cells. Transcriptomic analysis revealed that knocking out S100A9 significantly affected 123 DEGs, which were enriched in immune responses, defense responses against bacteria or lipopolysaccharides, cytokine-cytokine receptor interactions, and the IL-17 signaling pathway. Proteomic analysis revealed that S100A9 knockout alleviated muscle contraction dysfunction and structural remodeling in sepsis-induced ALI. Multiomics analysis revealed that S100A9 may be closely related to interferon-induced proteins with tetratricopeptide repeats and oligoadenylate synthase-like proteins. LPS decreased MLE12 cell activity, accompanied by high expression of S100A9. The expression of IL-17RA, pNFκB, and cleaved-caspase-3 were increased by S100A9 overexpression and reduced by S100A9 knockdown in LPS-stimulated MLE12 cells. S100A9 knockdown decreases transcription of apoptosis-related markers Bax, Bcl and caspase-3, alleviating LPS-induced apoptosis. ConclusionsS100A9 as a key biomarker of sepsis-induced acute lung injury, and exacerbates lung damage and epithelial cell apoptosis induced by LPS via the IL-17–NFκB–caspase-3 signaling pathway.

Physalin H ameliorates LPS-induced acute lung injury via KEAP1/NRF2 axis

Physalin H (PH), a withanolide isolated from Physalisangulata L. has been reported to have anti-inflammatory effect. However, its impact on acute lung injury (ALI) remains unexplored. In this study, we observed that PH significantly alleviated inflammation in LPS-stimulated macrophages by suppressing the release of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) and down-regulating the expression of the inflammation-related genes. RNA sequencing analysis revealed a significant up-regulation of the NRF2 pathway by PH. Further investigation elucidated that PH attenuated the ubiquitination of NRF2 by impeding the interaction between NRF2 and KEAP1, thereby facilitating NRF2 nuclear translocation and up-regulating the expression of target genes. Consequently, it regulated redox system and exerted anti-inflammatory effect. Consistently, PH also significantly alleviated pathological damage and inflammation in LPS-induced ALI mice model, which could be reversed by administration of an NRF2 inhibitor. Collectively, these results suggest that PH ameliorates ALI by activating the KEAP1/NRF2 pathway. These findings provide a foundation for further development of pH as a new anti-inflammatory agent for ALI therapy.

Icariin ameliorates LPS-induced acute lung injury in mice via complement C5a-C5aR1 and TLR4 signaling pathways

Acute lung injury (ALI) is an acute respiratory-related progressive disorder, which lacks specific pharmacotherapy. Icariin (ICA) has been shown to be effective in treating ALI. However, the targets and pharmacological mechanisms underlying the effects of ICA in the treatment of ALI are relatively lacking. Based on network pharmacology and molecular docking analyses, the gene functions and potential target pathways of ICA in the treatment of ALI were determined. In addition, the underlying mechanisms of ICA were verified by immunohistochemistry, immunofluorescence, quantitative Real-time PCR, and Western blot in LPS-induced ALI mice. The biological processes targeted by ICA in the treatment of ALI included the pathological changes, inflammatory response, and cell signal transduction. Network pharmacology, molecular docking, and in vivo experimental results revealed that ICA inhibited the complement C5a-C5aR1 axis, TLR4 mediated NF-κB, MAPK, and JAK2-STAT3 signaling pathways related gene and protein expressions, and decreased inflammatory cytokine, chemokine, adhesion molecule expressions, and mitochondrial apoptosis in LPS-induced ALI.

Protective Effect of Vitamin K2 (MK-7) on Acute Lung Injury Induced by Lipopolysaccharide in Mice.

Vitamin K2 (MK-7) has been shown to cause significant changes in different physiological processes and diseases, but its role in acute lung injury (ALI) is unclear. Therefore, in this study, we aimed to evaluate the protective effects of VK2 against LPS-induced ALI in mice. The male C57BL/6J mice were randomly divided into six groups (n = 7): the control group, LPS group, negative control group (LPS + Oil), positive control group (LPS + DEX), LPS + VK2 (L) group (VK2, 1.5 mg/kg), and LPS + VK2 (H) group (VK2, 15 mg/kg). Hematoxylin-eosin (HE) staining of lung tissue was performed. Antioxidant superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) activities, and the Ca2+ level in the lung tissue were measured. The effects of VK2 on inflammation, apoptosis, tight junction (TJ) injury, mitochondrial dysfunction, and autophagy were quantitatively assessed using Western blot analysis. Compared with the LPS group, VK2 improved histopathological changes; alleviated inflammation, apoptosis, and TJ injury; increased antioxidant enzyme activity; reduced Ca2+ overload; regulated mitochondrial function; and inhibited lung autophagy. These results indicate that VK2 could improve tight junction protein loss, inflammation, and cell apoptosis in LPS-induced ALI by inhibiting the mitochondrial dysfunction and excessive autophagy, indicating that VK2 plays a beneficial role in ALI and might be a potential therapeutic strategy.

Total synthesis and structural modification of the dibenzylbutane lignan LCA as a potent anti-inflammatory agent against LPS-induced acute lung injury

Acute lung injury (ALI) is a serious public health problem associated with high morbidity and mortality. However, few efficacious drugs are clinically available. Inhibition of proinflammatory cytokines is considered to be a promising method for the treatment of inflammatory diseases. Herein, the total synthesis of a dibenzylbutane lignan, 9′-O-di-(E)-feruloyl-meso-5,5′-dimethoxysecoisolariciresinol (LCA), was completed. A series of LCA derivatives were designed and synthesized, and their anti-inflammatory activities were evaluated. Derivative 14r significantly inhibited LPS-induced expression of NO and the proinflammatory cytokines TNF-α, IL-6, and IL-1β in RAW 264.7 cells and inhibited activation of the NF-κB pathway. Compound 14r reduced LPS-induced pulmonary inflammation and ALI in mice. It showed significant protective effects against LPS-induced ALI in mice and significantly reduced levels of proinflammatory cytokines in serum and bronchoalveolar lavage fluid. The ratio of wet weight to dry weight of lung tissue was normalized by compound 14r, which was consistent with suppression of neutrophil infiltration and production of proinflammatory cytokines. Compound 14r reduced the mRNA expression of some proinflammatory cytokines, improved histopathologic changes, and reduced macrophage infiltration in lung tissues. Collectively, these results suggest a new series of LCA derivatives that could be promising anti-inflammatory agents for ALI treatment.

ANXA3 interference inactivates ERK/ELK1 pathway to mitigate inflammation and apoptosis in sepsis-associated acute lung injury

Acute lung injury (ALI) is a prevailing and deadly complication of sepsis coupled with increasing incidence and fatality rate. Annexin A3 (ANXA3) has been unraveled to be upregulated during sepsis. This study purposed to assess the role and the mechanism of ANXA3 in sepsis-induced ALI. After the construction of mouse model of sepsis, the pathological changes of mice lung tissues were estimated by H&E staining. ANXA3 expression in mice lung tissues and serum was examined. The degree of pulmonary edema and the levels of inflammatory factors in bronchoalveolar lavage fluid (BALF) were analyzed. In lipopolysaccharide (LPS)-induced mouse ALI model in vitro, CCK-8 assay measured cell viability and flow cytometry analysis detected cell apoptosis. Besides, ELISA assay detected the release of inflammatory cytokines. Western blot analyzed the expression of proteins associated with inflammation, apoptosis and extracellular-signal-regulated kinase (ERK)/ETS-like gene 1 (ELK1) signaling. Results revealed that ANXA3 was overexpressed in the lung tissues and serum of septic mice. Following the knockdown of ANXA3, sepsis-induced lung injury was alleviated, manifested as reduced lung edema, decreased inflammatory cell infiltration and inhibited cell apoptosis. Additionally, ANXA3 silence blocked ERK/ELK1 signaling both in sepsis mouse models and in vitro model of ALI induced by lipopolysaccharide (LPS). Moreover, the inhibitory effects of ANXA3 silencing on ERK/ELK1 signaling activation, the viability damage, inflammation and apoptosis in LPS-induced mouse ALI model in vitro were partially reversed by ERK activator. Collectively, depletion of ANXA3 exerted suppressive effects on the inflammation and apoptosis in sepsis-induced ALI through blocking ERK/ELK1 signaling.

MiR-146a alleviates acute lung injury via inhibiting Notch 1 signaling pathway targeting macrophage.

Acute lung injury (ALI) is associated with the leukocyte infiltration and inflammation. Previous studies have shown that miR-146a is a valid regulator of the macrophage polarization in vitro inflammatory model. However, it is unclear whether miR-146a plays a protective role in ALI via modulating macrophage inflammation. To explore the potential therapeutic effect mechanism of miR-146a on ALI. We analyzed the expression of miR-146a in acute injured lung tissues and differentiated macrophage. Lipopolysaccharide (LPS) and interleukin-4 (IL-4) were employed in provoking the macrophage to polarization. We used miR-146a mimics to improve the overexpression of miR-146a and investigated the effect of increased miR-146a on LPS-induced ALI mice via the target of macrophage polarization. We showed that the expression of miR-146a markedly decreased in injured lung tissue and type M1 macrophage, while increased miR-146a expression exhibited in type M2 macrophage. Moreover, overexpression of miR-146a in LPS-induced macrophage reversed inflammatory M1 phenotype to anti-inflammatory M2 phenotype and mitigated inflammatory level via inhibiting Notch 1 signaling pathway. Hence, inflammation, infiltration, integrity of capillary barrier, and histology in ALI model were corrected after miR-146a overexpression treatment. These results suggested that miR-146a promotes type M2 macrophage polarization via restraining Notch 1 signaling pathway. Overexpression of miR-146a prevents inflammation damage and ameliorates lung damage after LPS induction. Therefore, miR-146a may serve as a promising target for the therapy of ALI in the future.

METTL14 contributes to acute lung injury by stabilizing NLRP3 expression in an IGF2BP2-dependent manner

Acute lung injury (ALI) as well as its more severe form, acute respiratory distress syndrome (ARDS), frequently leads to an uncontrolled inflammatory response. N6-methyladenosine (m6A) modification was associated with the progression of several inflammatory diseases. However, the role of methyltransferase-like 14 (METTL14)-mediated m6A methylation in ALI/ARDS remains unclear. Here, we reported an increase in overall expression levels of m6A and METTL14 in circulating monocyte-derived macrophages recruited to the lung following ALI, which is correlated with the severity of lung injury. We further demonstrated the critical function of METTL14 in activating NOD-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome in vitro and in mouse models of ALI/ARDS, and validated NLRP3 as the downstream target of METTL14 by the m6A RNA immunoprecipitation (MeRIP) and RIP assays. Mechanistically, METTL14-methylated NLRP3 transcripts were subsequently recognized by insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2), an m6A reader, which stabilized NLRP3 mRNA. Furthermore, we observed that IGF2BP2 knockdown diminished LPS-induced ALI in mice by downregulating NLRP3 expression. In summation, our study revealed that the molecular mechanism underlying the pathogenesis of ALI/ARDS involves METTL14-mediated activation of NLRP3 inflammasome in an IGF2BP2 dependent manner, thereby demonstrating the potential of METTL14 and IGF2BP2 as promising biomarkers and therapeutic targets for ALI/ARDS treatment.

Salecan ameliorates LPS-induced acute lung injury through regulating Keap1-Nrf2/HO-1 pathway in mice

Acute lung injury (ALI) is a severe clinical condition with high mortality, characterized by rapid onset and limited treatment options. The pathogenesis of ALI involves inflammation and oxidative stress. The polysaccharide salecan, a water-soluble β-(1,3)-D-glucan, has been found to possess numerous pharmaceutical effects, including anti-inflammatory properties, inhibition of oxidative stress, and anti-fatigue effects. This study aims to investigate the protective effect and underlying mechanism of salecan against LPS-induced ALI in mice. Using an in vivo LPS-induced ALI mouse model and an in vitro RAW264.7 cell system, we investigated the role of salecan in ALI with various experimental approaches, including histological staining, quantitative real-time PCR, flow cytometry, western blot analysis, and other relevant assays. Pre-treatment with salecan effectively attenuated LPS-induced ALI in vivo, reducing the severity of pulmonary edema, inflammation, and oxidative stress. NMR-based metabolomic profiling analysis revealed that salecan attenuated LPS-induced metabolic imbalances associated with ALI. Furthermore, salecan downregulated Keap1 and upregulated Nrf2 and HO-1 protein levels, indicating its modulation of the Keap1-Nrf2/HO-1 signaling pathway as a potential mechanism underlying its protective effects against ALI. In vitro studies on RAW264.7 cells revealed that salecan exhibited binding affinity towards macrophages, thereby alleviating LPS-induced apoptosis and inflammation, which underpin its therapeutic potential against ALI. Our study suggests that salecan can alleviate LPS-induced ALI by modulating oxidative stress, inflammatory response, and apoptosis through the activation of the Keap1-Nrf2/HO-1 pathway. These findings provide novel insights into the potential therapeutic use of salecan for the treatment of ALI.

Mechanism of isorhynchophylline in lipopolysaccharide-induced acute lung injury based on proteomic technology.

Isorhynchophylline (IRN), a tetracyclic indole alkaloid, has anti-inflammatory and antioxidant activities against cardiovascular diseases and central nervous system disorders. Acute lung injury (ALI) is a manifestation of inflammation concentrated in the lungs and has a high incidence rate and mortality The purpose of this study is to explain the mechanism of IRN in the treatment of acute lung injury and to provide a new scheme for clinical treatment. The experimental mice were divided into three groups: CTRL, LPS, LPS+IRN. The mouse model of ALI was established by inhaling LPS solution through nose. After continuous administration of IRN solution for 7 days, the mice in LPS+IRN group were killed and the lung tissue was collected for detection. Proteomic (Data are available via ProteomeXchange with identifier PXD050432) results showed that 5727 proteins were detected in mouse lung tissues, and 16 proteins were screened out. IRN could reverse the trend of these differential proteins. In addition, IRN can act on integrin αM to reduce neutrophil recruitment and thereby produce anti-inflammatory effects and may suppress neutrophil migration through the leukocyte transendothelial migration pathway. TUNEL and RT-PCR experiments revealed that LPS-induced ALI in mice increases the apoptosis of lung tissues, damage to alveolar epithelial cells and levels of inflammatory factors. Treatment with IRN can repair tissues, improve lung tissue pathology and reduce lung inflammation.

Naked Gene Delivery Induces Autophagy for Effective Treatment of Acute Lung Injury in a Mouse Model.

Acute lung injury (ALI) leads to diffuse pulmonary interstitial and alveolar edema, further developing into acute respiratory distress syndrome (ARDS). The present therapeutic approaches showed limited effects with poor clinical efficacy or severe side effects. This study aims to develop novel pharmaceutical agents to reduce lung damage with acceptable side effects for ALI. Naked gene delivery system based on epigallocatechin 3-gallate (EGCG) was synthesized to deliver plasmid expressing DNA damage regulated autophagy modulator 1 (DRAM1), designated as EGCG/DRAM1 (ED). ED was characterized by dynamic light scattering analysis and transmission electron microscope. The biodistribution of ED in mice was measured by an in vivo small animal imaging system. The therapeutic potentials of ED were evaluated in MLE12 cells and LPS-induced ALI mice. Our results showed that ED was nearly spherical with a diameter of ~100 nm and increased the stability of DRAM1 plasmid that encapsulated. The synthesized ED showed negligible toxicity at the selected experimental concentration in MLE12 cells. ED could be taken up by MLE12 cells with high efficiency and escape from the lysosome. In ALI mice, ED facilitated the accumulation and retention of DRAM1 plasmid in lung, and attenuated pulmonary edema and pulmonary vascular permeability. The therapeutic effects of ED on ALI were associated with increased autophagy and reduced oxidative stress in lung. In summary, ED attenuated pulmonary edema and pulmonary vascular permeability, and improved pulmonary dysfunction in ALI mice. This naked gene delivery system for autophagy enhancement may serve as a potential therapeutic strategy to attenuate ALI.

Tangeretin attenuates acute lung injury in septic mice by inhibiting ROS-mediated NLRP3 inflammasome activation via regulating PLK1/AMPK/DRP1 signaling axis.

NLRP3 inflammasome-mediated pyroptosis of macrophage acts essential roles in the progression of sepsis-induced acute lung injury (ALI). Tangeretin (TAN), enriched in citrus fruit peel, presents anti-oxidative and anti-inflammatory effects. Here, we aimed to explore the potentially protective effect of TAN on sepsis-induced ALI, and the underlying mechanism of TAN in regulating NLRP3 inflammasome. The effect of TAN on sepsis-induced ALI and NLRP3 inflammasome-mediated pyroptosis of macrophage were examined in vivo and in vitro using a LPS-treated mice model and LPS-induced murine macrophages, respectively. The mechanism of TAN regulating the activation of NLRP3 inflammasome in sepsis-induced ALI was investigated with HE staining, Masson staining, immunofluorescent staining, ELISA, molecular docking, transmission electron microscope detection, qRT-PCR, and western blot. TAN could evidently attenuate sepsis-induced ALI in mice, evidenced by reducing pulmonary edema, pulmonary congestion and lung interstitial fibrosis, and inhibiting macrophage infiltration in the lung tissue. Besides, TAN significantly suppressed inflammatory cytokine IL-1β and IL-18 expression in the serum or bronchoalveolar lavage fluid (BALF) samples of mice with LPS-induced ALI, and inhibited NLRP3 inflammasome-mediated pyroptosis of macrophages. Furthermore, we found TAN inhibited ROS production, preserved mitochondrial morphology, and alleviated excessive mitochondrial fission in LPS-induced ALI in mice. Through bioinformatic analysis and molecular docking, Polo-like kinase 1 (PLK1) was identified as a potential target of TAN for treating sepsis-induced ALI. Moreover, TAN significantly inhibited the reduction of PLK1 expression, AMP-activated protein kinase (AMPK) phosphorylation, and Dynamin related protein 1 (Drp1) phosphorylation (S637) in LPS-induced ALI in mice. In addition, Volasertib, a specific inhibitor of PLK1, abolished the protective effects of TAN against NLRP3 inflammasome-mediated pyroptosis of macrophage and lung injury in the cell and mice septic models. TAN attenuates sepsis-induced ALI by inhibiting ROS-mediated NLRP3 inflammasome activation via regulating PLK1/AMPK/DRP1 signaling axis, and TAN is a potentially therapeutic candidate against ALI through inhibiting pyroptosis.

Adhesion molecule-targeted magnetic particle imaging nanoprobe for visualization of inflammation in acute lung injury.

Uncontrolled intra-alveolar inflammation is a central pathogenic feature, and its severity translates into a valid prognostic indicator of acute lung injury (ALI). Unfortunately, current clinical imaging approaches are unsuitable for visualizing and quantifying intra-alveolar inflammation. This study aimed to construct a small-sized vascular cell adhesion molecule-1 (VCAM-1)-targeted magnetic particle imaging (MPI) nanoprobe (ESPVPN) to visualize and accurately quantify intra-alveolar inflammation at the molecular level. ESPVPN was engineered by conjugating a peptide (VHPKQHRGGSK(Cy7)GC) onto a polydopamine-functionalized superparamagnetic iron oxide core. The MPI performance, targeting, and biosafety of the ESPVPN were characterized. VCAM-1 expression in HUVECs and mouse models was evaluated by western blot. The degree of inflammation and distribution of VCAM-1 in the lungs were assessed using histopathology. The expression of pro-inflammatory markers and VCAM-1 in lung tissue lysates was measured using ELISA. After intravenous administration of ESPVPN, MPI and CT imaging were used to analyze the distribution of ESPVPN in the lungs of the LPS-induced ALI models. The small-sized (~10 nm) ESPVPN exhibited superior MPI performance compared to commercial MagImaging® and Vivotrax, and ESPVPN had effective targeting and biosafety. VCAM-1 was highly expressed in LPS-induced ALI mice. VCAM-1 expression was positively correlated with the LPS-induced dose (R = 0.9381). The in vivo MPI signal showed positive correlations with both VCAM-1 expression (R = 0.9186) and representative pro-inflammatory markers (MPO, TNF-α, IL-6, IL-8, and IL-1β, R > 0.7). ESPVPN effectively targeted inflammatory lungs and combined the advantages of MPI quantitative imaging to visualize and evaluate the degree of ALI inflammation.

Protective Effects of Danmu Extract Syrup on Acute Lung Injury Induced by Lipopolysaccharide in Mice through Endothelial Barrier Repair.

To investigate the effects of Danmu Extract Syrup (DMS) on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice and explore the mechanism. Seventy-two male Balb/C mice were randomly divided into 6 groups according to a random number table (n=12), including control (normal saline), LPS (5 mg/kg), LPS+DMS 2.5 mL/kg, LPS+DMS 5 mL/kg, LPS+DMS 10 mL/kg, and LPS+Dexamethasone (DXM, 5 mg/kg) groups. After pretreatment with DMS and DXM, the ALI mice model was induced by LPS, and the bronchoalveolar lavage fluid (BALF) were collected to determine protein concentration, cell counts and inflammatory cytokines. The lung tissues of mice were stained with hematoxylin-eosin, and the wet/dry weight ratio (W/D) of lung tissue was calculated. The levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-1 β in BALF of mice were detected by enzyme linked immunosorbent assay. The expression levels of Claudin-5, vascular endothelial (VE)-cadherin, vascular endothelial growth factor (VEGF), phospho-protein kinase B (p-Akt) and Akt were detected by Western blot analysis. DMS pre-treatment significantly ameliorated lung histopathological changes. Compared with the LPS group, the W/D ratio and protein contents in BALF were obviously reduced after DMS pretreatment (P<0.05 or P<0.01). The number of cells in BALF and myeloperoxidase (MPO) activity decreased significantly after DMS pretreatment (P<0.05 or P<0.01). DMS pre-treatment decreased the levels of TNF-α, IL-6 and IL-1 β (P<0.01). Meanwhile, DMS activated the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) pathway and reversed the expressions of Claudin-5, VE-cadherin and VEGF (P<0.01). DMS attenuated LPS-induced ALI in mice through repairing endothelial barrier. It might be a potential therapeutic drug for LPS-induced lung injury.

GLUT1 contributes to impaired epithelial tight junction in the late phase of acute lung injury

Dysfunction of epithelial barrier is crucial for the development of acute lung injury (ALI). This study was aimed to evaluate the role of glucose transporter 1 (GLUT1) in dysregulation of epithelial tight junction in ALI. GLUT1 was inhibited with specific antagonists WZB117 or BAY876 to see the effects on epithelial tight junction in a well-established LPS-induced mouse ALI model as well as in vitro cultured epithelial cells. Pharmacological inhibition of GLUT1 with WZB117 at either a low or high dose had no effects on lung injury and inflammation 24 h after LPS challenge, but significantly decreased the pulmonary inflammatory responses induced by LPS at 72 h with a high dose, which was verified by treatment with BAY876. WZB117 or BAY876 also recovered the expression of epithelial tight junction proteins ZO-1 and occludin. In cultured BEAS-2B and A549 cells, LPS induced increased GLUT1 expression, accompanied by decreased expression of tight junction protein ZO-1 and occludin. Blockade of GLUT1 restored LPS-induced disruption of ZO-1 and occludin in BEAS-2B rather than A549. Taken together, our results showed that GLUT1 is responsible for dysfunction of epithelial tight junctions in the late phase of LPS-induced ALI.

Kaempferitrin alleviates LPS-induced septic acute lung injury in mice through downregulating NF-κB pathway.

Acute lung injury (ALI) causes severe and uncontrolled pulmonary inflammation and has high morbidity in dying patients. This study aimed to evaluate the potential function of Kaempferitrin (Kae) and uncover its mechanisms in ALI. We evaluated the role of Kae in ALI through the lipopolysaccharide (LPS)-induced histopathological changes, lung wet/dry (W/D) ratio, total bronchoalveolar lavage fluid (BALF) cells count, pulmonary inflammation, and the levels of interleukin (IL)-6, tumor necrosis factor-α (TNF-α), and IL-1β. The effect of Kae on NF-κB signaling pathway was discovered through the protein expression levels of transcription factors p65, p-p65, IκBα, and p-IκBα by Western blot analysis. The results showed that Kae could improve lung injury by reducing apoptosis, histopathological changes, and lung W/D ratio; more importantly, Kae enhanced the survival of ALI mice. Moreover, Kae relieved inflammation, as it reduced total BALF cells count, and deceased the levels of TNF-α, IL-6, and IL-1β in serum. In addition, Western blot analysis data suggested that Kae could decrease the protein expression levels of transcription factors p65, p-p65, IκB-α, and p-IκB-α, which were promoted by LPS. The results of this study suggested that Kae could relieve LPS-induced ALI in mice and reduce inflammation and apoptosis through NF-κB pathway.

Alismol Purified from the Tuber of Alisma orientale Relieves Acute Lung Injury in Mice via Nrf2 Activation.

Since the ethanol extract of Alisma orientale Juzepzuk (EEAO) suppresses lung inflammation by suppressing Nuclear Factor-kappa B (NF-κB) and activating Nuclear Factor Erythroid 2-related Factor 2 (Nrf2), we set out to identify chemicals constituting EEAO that suppress lung inflammation. Here, we provide evidence that among the five most abundant chemical constituents identified by Ultra Performance Liquid Chromatography (UPLC) and Nuclear Magnetic Resonance (NMR), alismol is one of the candidate constituents that suppresses lung inflammation in a lipopolysaccharide (LPS)-induced acute lung injury (ALI) mouse model and protects mice from ALI-like symptoms. Alismol did not induce cytotoxicity or reactive oxygen species (ROS). When administered to the lung of LPS-induced ALI mice (n = 5/group), alismol decreased the level of neutrophils and of the pro-inflammatory molecules, including Tumor Necrosis Factor-alpha (TNF-α), Interleukin-1 beta (IL-1β), Interleukin-6 (IL-6), Monocyte Chemoattractant Protein-1 (MCP-1), Interferon-gamma (IFN-γ), and Cyclooxygenase-2 (COX-2), suggesting an anti-inflammatory activity of alismol. Consistent with these findings, alismol ameliorated the key features of the inflamed lung of ALI, such as high cellularity due to infiltrated inflammatory cells, the development of hyaline membrane structure, and capillary destruction. Unlike EEAO, alismol did not suppress NF-κB activity but rather activated Nrf2. Consequently, alismol induced the expression of prototypic genes regulated by Nrf2, including Heme Oxygenase-1 (HO-1), NAD(P)H: quinine oxidoreductase-1 (NQO-1), and glutamyl cysteine ligase catalytic units (GCLC). Alismol activating Nrf2 appears to be associated with a decrease in the ubiquitination of Nrf2, a key suppressive mechanism for Nrf2 activity. Together, our results suggest that alismol is a chemical constituent of EEAO that contributes at least in part to suppressing some of the key features of ALI by activating Nrf2.

DMPP attenuates lipopolysaccharide-induced lung injury by inhibiting glycocalyx degradation through activation of the cholinergic anti-inflammatory pathway.

The study aimed to investigate the therapeutic potential of 1,1-dimethyl-4-phenylpiperazinium iodide (DMPP), an agonist of nicotinic acetylcholine receptor (nAChR), in treating acute lung injury (ALI) induced by lipopolysaccharide (LPS). A murine ALI model was developed utilizing intraperitoneal injection of LPS. We evaluated the therapeutic efficacy of DMPP treatment in LPS-induced lung injury using various approaches, including pathohistological evaluation, appraisal of pulmonary edema, and measurement of inflammatory cytokine levels and their associated pathways within lung tissues. The gene chip data of LPS-induced acute lung injury mice were retrieved from the Gene Expression Omnibus (GEO) database for gene differential expression analysis and Gene Set Enrichment Analysis (GSEA) analysis. The impact of DMPP on glycocalyx shedding was assessed by measuring the expression levels of syndecan-1 (SDC-1) and matrix metalloproteinase-9 (MMP-9). DMPP treatment significantly improved pathomorphological changes and pathological lung injury scores in the LPS-induced ALI mouse model. The genes expressed differentially in the LPS-induced ALI group in GSE2411 were found to be involved in multiple processes, including the NF-κB signaling pathway, NOD-like receptor signaling pathway, Toll-like receptor signaling pathway, as well as the JAK-STAT signaling pathway. DMPP treatment effectively downregulated pro-inflammatory cytokines, suppressed the NF-κB signaling pathway, and effectively restrained the LPS-induced upregulation of MMP-9 and shedding of syndecan-1, thereby contributing to the preservation of endothelial glycocalyx and attenuation of endothelial barrier dysfunction. The administration of DMPP has been shown to confer protection against LPS-induced acute lung injury via a cholinergic anti-inflammatory pathway, which effectively inhibits endothelial glycocalyx degradation.

A natural sesquiterpene lactone isolinderalactone attenuates lipopolysaccharide-induced inflammatory response and acute lung injury through inhibition of NF-κB pathway and activation Nrf2 pathway in macrophages

Isolinderalactone is the main sesquiterpene lactone isolated from Lindera aggregata, a traditional Chinese medicine widely used to treat pain and inflammation. Although isolinderalactone has been demonstrated to possess anti-cancer effect, its anti-inflammatory activity and underlying mechanism has not been well characterized. Herein, isolinderalactone was able to significantly inhibit the production of NO and PGE2 by reducing the expressions of iNOS and COX2 in LPS-stimulated RAW264.7 macrophages and BMDMs, and decreased the mRNA levels of IL-1β, IL-6, and TNF-α in LPS-induced RAW264.7 cells. In vivo, isolinderalactone effectively alleviated LPS-induced acute lung injury (ALI), which manifested as reduction in pulmonary inflammatory infiltration, myeloperoxidase activity, and production of PGE2, IL-1β, IL-6, TNF-α, and malondialdehyde. Furthermore, isolinderalactone inhibited phosphorylation of IKKα/β, phosphorylation and degradation of IκBα, and nuclear translocation of NF-κB p65, thereby blocking NF-κB pro-inflammatory pathway. Meanwhile, isolinderalactone reduced the intracellular ROS through promoting the activation of Nrf2-HMOX1 antioxidant axis. By using drug affinity responsive target stability assay and molecular docking, isolinderalactone was found to covalently interact with IKKα/β and Keap1, which may contribute to its anti-inflammatory action. Additionally, a thiol donor β-mercaptoethanol significantly abolished isolinderalactone-mediated anti-inflammatory action in vitro, indicating the crucial role of the unsaturated lactone of isolinderalactone on its anti-inflammatory effects. Taken together, isolinderalactone protected against LPS-induced ALI in mice, which may be associated with its inhibition of NF-κB pathway and activation of Nrf2 signaling in macrophages.

Design, synthesis and anti-inflammatory activity study of lansiumamide analogues for treatment of acute lung injury

Acute lung injury (ALI) is an inflammation-mediated respiratory disease with a high mortality rate. Medications with anti-inflammatory small molecules have been demonstrated in phase I and II clinical trials to considerably reduce the ALI mortality. In this study, two series of lansiumamide analogues were designed, synthesized, and evaluated for anti-inflammatory activity for ALI treatment. We found that compound 8n exhibited the best anti-inflammatory activity through inhibiting LPS-induced expression of the proinflammatory cytokines interleukin-6 (IL-6) and interleukin-1β (IL-1β) in Raw264.7 cells and activating the Nrf2/HO-1 pathway. Furthermore, we discovered in a LPS-induced ALI mice model that compound 8n significantly reduced the infiltration of inflammatory cells into lung tissue to achieve the effect of protecting lung tissues and improving ALI. Additionally, our mice model study revealed that compound 8n had a good expectorant effect. These results consistently support that lansiumamide analogue 8n represents a new class of anti-inflammatory agents with potential as a lead compound for further development into a therapeutic drug for ALI treatment.