Ghrelin attenuates sepsis-induced acute lung injury by inhibiting the NF-κB, iNOS, and Akt signaling in alveolar macrophages

Ghrelin has proven to be protective against sepsis-induced acute lung injury (ALI) via anti-inflammatory effects. However, its mechanisms remain poorly understood. Alveolar macrophages (AMs) play a key role in mediating inflammatory responses during sepsis-induced ALI by secretion of cytokines and chemokines. This study was undertaken to investigate whether ghrelin suppresses inflammatory effects of AMs and therefore may help to attenuate sepsis-induced ALI. A sepsis model in rats was achieved using cecal ligation and puncture. Ghrelin treatment markedly improved histopathological changes in the lungs and reduced pulmonary inflammation in septic rats. NF-κB translocation and p-Akt and inducible nitric oxide synthase (iNOS) activities in AMs from septic rats were suppressed by ghrelin. In vitro data indicated that ghrelin decreased the levels of LPS-induced IL-1β, TNF-α, and IL-6, NF-κB translocation, and iNOS and Akt activities of AMs. Furthermore, the NF-κB/iNOS pathway or Akt signaling was positively correlated with LPS-induced inflammatory production of AMs in vitro. In conclusion, ghrelin exerts a protective role against sepsis-induced ALI probably by reducing the production of inflammatory cytokines from AMs via inhibition of the NF-κB/iNOS pathway or Akt signaling.

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Geranylgeranyl diphosphate synthase deficiency hyperactivates macrophages and aggravates lipopolysaccharide-induced acute lung injury

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00281.2020 ◽

2021 ◽

Author(s):

Jiajia Jin ◽

Hong Qian ◽

Bing Wan ◽

Li Zhou ◽

Cen Chen ◽

...

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Alveolar Macrophages ◽

Macrophage Activation ◽

Nuclear Translocation ◽

Inflammatory Responses ◽

Alveolar Epithelium ◽

Geranylgeranyl Diphosphate Synthase ◽

Geranylgeranyl Diphosphate

Macrophage activation is a key contributing factor for excessive inflammatory responses of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Geranylgeranyl diphosphate synthase (GGPPS) plays a key role in the development of inflammatory diseases. Our group previously showed that GGPPS in alveolar epithelium have deleterious effects on acute lung injury induced by LPS or mechanical ventilation. Herein, we examined the role of GGPPS in modulating macrophage activation in ALI/ARDS. We found significant increased GGPPS expression in alveolar macrophages in ARDS patients compared to healthy volunteers and in ALI mice induced by LPS. GGPPS-floxed control (GGPPSfl/fl) and myeloid-selective knockout (GGPPSfl/flLysMcre) mice were then generated. Interestingly, using a LPS-induced ALI mouse model, we showed that myeloid-specific GGPPS knockout significantly increased mortality, aggravated lung injury, and increased the accumulation of inflammatory cells, total protein, and inflammatory cytokines in BALF. In vitro, GGPPS deficiency up-regulated the production of LPS-induced IL-6, IL-1β, and TNF-α in alveolar macrophages, bone marrow-derived macrophages (BMDMs), and THP-1 cells. Mechanistically, GGPPS knockout increased phosphorylation and nuclear translocation of NF-κB p65 induced by LPS. In addition, GGPPS deficiency increased the level of GTP-Rac1, which was responsible for NF-κB activation. In conclusion, decreased expression of GGPPS in macrophages aggravates lung injury and inflammation in ARDS, at least partly by regulating Rac1-dependent NF-κB signaling. GGPPS in macrophages may represent a novel therapeutic target in ARDS.

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Exosomes Derived From Alveolar Epithelial Cells Promote Alveolar Macrophage Activation Mediated by miR-92a-3p in Sepsis-Induced Acute Lung Injury

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2021.646546 ◽

2021 ◽

Vol 11 ◽

Author(s):

Fen Liu ◽

Wei Peng ◽

Jiaquan Chen ◽

Zeyao Xu ◽

Rong Jiang ◽

...

Keyword(s):

Acute Lung Injury ◽

Epithelial Cells ◽

Lung Injury ◽

Pulmonary Inflammation ◽

Cecal Ligation ◽

Alveolar Epithelial Cells ◽

Luciferase Reporter ◽

Alveolar Epithelial

Acute lung injury (ALI) induced by sepsis is characterized by disruption of the epithelial barrier and activation of alveolar macrophages (AMs), which leads to uncontrolled pulmonary inflammation. However, effective treatments for ALI are unavailable. The exact mechanism by which the initial mediator of alveolar epithelial cells (AECs) induces inflammation remains elusive. Here we investigated the roles of AEC-derived exosomes in AM activation and sepsis-induced ALI in vivo and in vitro. Cecal ligation and puncture (CLP) was utilized to establish septic lung injury model in rats. The effect of exosomal inhibition by intratracheal GW4869 administration on lung injury was investigated. To assess the effects of AEC-derived exosomes on ALI, we treated the rat alveolar epithelial cell line RLE-6TN with LPS to induce cell damage. Exosomes from conditioned medium of LPS-treated AECs (LPS-Exos) were isolated by ultracentrifugation. The miRNAs in LPS-Exos were screened by miRNA expression profile analysis. The effects of miR-92a-3p on the function of AMs were studied. We found that intratracheal GW4869 administration ameliorated lung injury following CLP-induced ALI. LPS-Exos were taken up by AMs and activated these cells. Consistently, administration of LPS-Exos in rats significantly aggravated pulmonary inflammation and alveolar permeability. Moreover, miR-92a-3p was enriched in LPS-Exos and could be delivered to AMs. Inhibition of miR-92a-3p in AECs diminished the proinflammatory effects of LPS-Exos in vivo and in vitro. Mechanistically, miR-92a-3p activates AMs along with pulmonary inflammation. This process results in activation of the NF-κB pathway and downregulation of PTEN expression, which was confirmed by a luciferase reporter assay. In conclusion, AEC-derived exosomes activate AMs and induce pulmonary inflammation mediated by miR-92a-3p in ALI. The present findings revealed a previously unidentified role of exosomal miR-92a-3p in mediating the crosstalk between injured AEC and AMs. miR-92a-3p in AEC exosomes might represent a novel diagnostic biomarker for ALI, which may lead to a new therapeutic approach.

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Inhaled nitric oxide attenuates acute lung injury via inhibition of nuclear factor-κB and inflammation

Journal of Applied Physiology ◽

10.1152/japplphysiol.00202.2001 ◽

2002 ◽

Vol 92 (2) ◽

pp. 795-801 ◽

Cited By ~ 59

Author(s):

Jihee Lee Kang ◽

Wann Park ◽

In Soon Pack ◽

Hui Su Lee ◽

Mi Jung Kim ◽

...

Keyword(s):

Nitric Oxide ◽

Acute Lung Injury ◽

Lung Injury ◽

Alveolar Macrophages ◽

Inflammatory Responses ◽

Pulmonary Inflammation ◽

Nuclear Factor Κb ◽

Inhaled Nitric Oxide ◽

Nuclear Factor ◽

Inhaled No

The effect of inhaled nitric oxide (NO) on inflammatory process in acute lung injury (ALI) is unclear. The aims of this study were to 1) examine whether inhaled NO affects the biochemical lung injury parameters and cellular inflammatory responses and 2) determine the effect of inhaled NO on the activation of nuclear factor-κB (NF-κB) in lipopolysaccharide (LPS)-induced ALI. Compared with saline controls, rabbits treated intravenously with LPS showed increases in total protein and lactate dehydrogenase in the bronchoalveolar lavage (BAL) fluid, indicating ALI. LPS-treated animals with NO inhalation (LPS-NO) showed significant decreases in these parameters. Neutrophil numbers in the BAL fluid, the activity of reactive oxygen species in BAL cells, and the levels of interleukin (IL)-1β and IL-8 in alveolar macrophages were increased in LPS-treated animals. In contrast, neutrophil numbers and these cellular activities were substantially decreased in LPS-NO animals, compared with LPS-treated animals. NF-κB activation in alveolar macrophages from LPS-treated animals was also markedly increased, whereas this activity was effectively blocked in LPS-NO animals. These results suggest that inhaled NO attenuates LPS-induced ALI and pulmonary inflammation. This attenuation may be associated with the inhibition of NF-κB activation.

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Down-regulation of SNHG16 alleviates the acute lung injury in sepsis rats through miR-128-3p/HMGB3 axis

BMC Pulmonary Medicine ◽

10.1186/s12890-021-01552-0 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Junli Sun ◽

Keke Xin ◽

Chenghui Leng ◽

Jianlin Ge

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Western Blot ◽

Cell Viability ◽

Inflammatory Diseases ◽

Cecal Ligation ◽

Inflammatory Factors ◽

Lung Epithelial

Abstract Background Long noncoding RNAs contribute to various inflammatory diseases, including sepsis. We explore the role of small nucleolar RNA host gene 16 (SNHG16) in sepsis-mediated acute lung injury (ALI) and inflammation. Methods A sepsis-induced ALI rat model was constructed by the cecal ligation and perforation method. The profiles of SNHG16, miR-128-3p, and high-mobility group box 3 (HMGB3) were monitored by quantitative reverse transcription PCR and Western blot. The pathologic changes of lung tissues were evaluated by Hematoxylin–Eosin staining, immunohistochemistry, and dry and wet method. Meanwhile, the pro-inflammatory factors and proteins were determined by ELISA and Western blot. In contrast, a sepsis model in BEAS-2B was induced with lipopolysaccharide (LPS) to verify the effects of SNHG16/miR-128-3p/HMGB3 on lung epithelial cell viability and apoptosis. Results As a result, SNHG16 and HMGB3 were up-regulated, while miR-128-3p was down-regulated in sepsis-induced ALI both in vivo and in vitro. Inhibiting SNHG16 reduced the apoptosis and inflammation in the sepsis-induced ALI model. Overexpressing SNHG16 promoted LPS-mediated lung epithelial apoptosis and inhibited cell viability and inflammation, while miR-128-3p had the opposite effects. Mechanistically, SNHG16 targeted miR-128-3p and attenuated its expression, while miR-128-3p targeted the 3′ untranslated region of HMGB3. Conclusions Overall, down-regulating SNHG16 alleviated the sepsis-mediated ALI by regulating miR-128-3p/HMGB3.

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GLP-1 Analogue Liraglutide Enhances SP-A Expression in LPS-Induced Acute Lung Injury through the TTF-1 Signaling Pathway

Mediators of Inflammation ◽

10.1155/2018/3601454 ◽

2018 ◽

Vol 2018 ◽

pp. 1-14 ◽

Cited By ~ 16

Author(s):

Tao Zhu ◽

Changyi Li ◽

Xue Zhang ◽

Chunyan Ye ◽

Shuo Tang ◽

...

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Signaling Pathway ◽

Pulmonary Inflammation ◽

Protein A ◽

Insulin Level ◽

Underlying Mechanism ◽

Ultrastructural Changes

The reduction of pulmonary surfactant (PS) is essential for decreased pulmonary compliance and edema in acute lung injury (ALI). Thyroid transcription factor-1 (TTF-1) plays a major role in the regulation of surfactant protein-A (SP-A), the most abundant protein component of PS. Simultaneously, the glucagon-like peptide-1 (GLP-1) analogue can enhance SP-A expression in the lung. However, the underlying mechanism is still unknown. The purpose of this study was to explore whether liraglutide, a GLP-1 analogue, upregulates SP-A expression through the TTF-1 signaling pathway in ALI. In vivo, a murine model of ALI was induced by lipopolysaccharide (LPS). Pulmonary inflammation, edema, insulin level, ultrastructural changes in type II alveolar epithelial (ATII) cells, and SP-A and TTF-1 expression were analyzed. In vitro, rat ATII cells were obtained. SP-A and TTF-1 expression in cells was measured. ShRNA-TTF-1 transfection was performed to knock down TTF-1 expression. Our data showed that LPS-induced lung injury and increase in insulin level, and LPS-induced reduction of SP-A and TTF-1 expression in both the lung and cells, were significantly compromised by liraglutide. Furthermore, we also found that these effects of liraglutide were markedly blunted by shRNA-TTF-1. Taken together, our findings suggest that liraglutide enhances SP-A expression in ATII cells and attenuates pulmonary inflammation in LPS-induced ALI, most likely through the TTF-1 signaling pathway.

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Mesenchymal Stem Cells Attenuate Acute Lung Injury in Mice Partly by Suppressing Alveolar Macrophage Activation in a PGE2-dependent Manner

10.21203/rs.3.rs-664786/v1 ◽

2021 ◽

Author(s):

Gaojian Wang ◽

Yaping Zhang ◽

Nianqiang Hu ◽

Qinxue Liu ◽

Fengjie Ma ◽

...

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Alveolar Macrophage ◽

Alveolar Macrophages ◽

Macrophage Activation ◽

Rna Seq ◽

Ep4 Receptor ◽

Pge2 Receptor ◽

Cox2 Inhibitor

Abstract Background: Mesenchymal stem cell have shown therapeutic effect on acute lung injury, MSC could be activated when added to inflammatory environment and in turn suppress inflammation, yet the mechanism is complex and not understood. Methods: To determine the effect of MSC on ALI and alveolar macrophage activation, MSCs were administered to ALI mice and co-cultured with activated MH-S cells (alveolar macrophage cell line). To find the genes critical for MSC’s immunosuppressive effects, rest and activated MSCs induced by inflammatory MH-S cells were harvested for RNA-seq. To prove that PGE2 participates in the immunosuppressive effects of MSC, COX2 inhibitor and PGE2 receptor antagonist were added to the co-culture system and administrated to ALI mice. Results: The intratracheal administration of MSCs attenuated ALI and suppressed alveolar macrophages activation in vivo, the activation of MH-S cells was also significantly reduced after co-culturing with MSCs in vitro. The RNA-seq data of rest and activated MSCs suggested that the Ptgs2 gene may play an important role in MSC exerting immunosuppressive effects. Correspondingly, we found that the COX2 protein and PGE2 released by activated MSCs were increased dramatically after co-culturing with MH-S. The use of COX2 inhibitor NS-398 restrained the secretion of PGE2 and reversed the suppressive effect on macrophages activation of MSCs in vitro. Furthermore, GW627368X, a selective antagonist of PGE2 receptor (EP4 receptor), also reversed the inhibitory effects of MSCs on alveolar macrophages and their protective effects on ALI mice.Conclusions: MSC attenuate ALI partly through suppressing alveolar macrophage activation via PGE2 binding to EP4 receptor.

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Biocompatible N-acetyl-nanoconstruct alleviates lipopolysaccharide-induced acute lung injury in vivo

Scientific Reports ◽

10.1038/s41598-021-01624-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Seongchan Kim ◽

Shin Young Kim ◽

Seung Joon Rho ◽

Seung Hoon Kim ◽

So Hyang Song ◽

...

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Inflammatory Responses ◽

Therapeutic Potential ◽

Intratracheal Instillation ◽

Sprague Dawley ◽

In Vivo Experiments ◽

Anti Inflammatory

AbstractOxidative stress plays important roles in inflammatory responses during acute lung injury (ALI). Recently, nanoconstruct (Nano)-based drug-delivery systems have shown promise in many models of inflammation. In this study, we evaluated the anti-inflammatory effects of N-acetylcysteine (NAC) loaded in a biocompatible Nano using a rat model of ALI. We synthesized a Nano with a good NAC-releasing capacity using porous silica Nano, which was used to produce Nano/NAC complexes. For in vivo experiments, Sprague–Dawley rats were intraperitoneally administered NAC or Nano/NAC 30 min after intratracheal instillation of lipopolysaccharide. After 6 h, bronchoalveolar lavage fluids and lung tissues were collected. The anti-oxidative effect of the Nano/NAC complex was confirmed by demonstrating reduced levels of reactive oxygen species after treatment with the Nano/NAC in vitro. In vivo experiments also showed that the Nano/NAC treatment may protect against LPS‐induced ALI thorough anti‐oxidative and anti‐inflammatory effects, which may be attributed to the inactivation of the NF‐κB and MAPK pathways. In addition, the effects of Nano/NAC treatment were shown to be superior to those of NAC alone. We suggest the therapeutic potential of Nano/NAC treatment as an anti‐inflammatory agent against ALI. Furthermore, our study can provide basic data for developing nanotechnology-based pharmacotherapeutics for ALI.

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MiR-574-5p alleviates sepsis-induced acute lung injury by regulating TRAF6/NF-κB pathway

Tropical Journal of Pharmaceutical Research ◽

10.4314/tjpr.v19i4.1 ◽

2020 ◽

Vol 19 (4) ◽

pp. 676-682

Author(s):

Changfu Xu ◽

Lei Chong ◽

Gang Yu ◽

Hailin Zhang

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Inflammatory Cell ◽

Inflammatory Responses ◽

Cecal Ligation ◽

Cytokine Expression ◽

Inflammatory Cell Infiltration ◽

Luciferase Assay ◽

Cell Infiltration ◽

Mice Model

Purpose: To investigate the protective effect of miR-574-5p pretreatment against acute lung injury (ALI) induced by sepsis.Methods: A male C57BL/6 mouse model of sepsis-induced ALI was established by cecal ligation and puncture (CLP) and treated with miR-574-5p agomir (intravenous injection, 80 mg/kg per day, 3 days). After that, blood and lung samples were obtained for histopathological observation. Myeloperoxidase (MPO) activity, inflammatory cell infiltration, and cytokine expression were analyzed. The target gene of miR-574-5p was predicted using TargetScan prediction, and verified by luciferase assay and western blot.Results: In sepsis-induced ALI mice model, downregulation of miR-574-5p was observed. Pretreatment of miR-574-5p significantly alleviated ALI by suppressing histological damage, and reducing MPO activity and inflammatory cell infiltration, as well as decreasing cytokine expression. The underlying mechanism was that miR-574-5p targeted TNF receptor associated factor 6 (TRAF6) and suppressed the downstream NF-κB pathway. Moreover, TRAF6 overexpression reversed the effects of miR-574-5p on ALI.Conclusion: MiR-574-5p pretreatment suppresses inflammatory responses, thus reducing lung injury induced by sepsis in mice, partly via the regulation of TRAF6 and NF-κB pathway. Therefore, this approach can potentially be used for the clinical management of ALI in humans Keywords: Sepsis, Acute lung injury, MiR-574-5p, TRAF6, NF-κB pathway

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Phagocytosis of microparticles by alveolar macrophages during acute lung injury requires MerTK

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00058.2017 ◽

2018 ◽

Vol 314 (1) ◽

pp. L69-L82 ◽

Cited By ~ 12

Author(s):

Michael P. Mohning ◽

Stacey M. Thomas ◽

Lea Barthel ◽

Kara J. Mould ◽

Alexandria L. McCubbrey ◽

...

Keyword(s):

Acute Lung Injury ◽

Lung Injury ◽

Alveolar Macrophages ◽

Primary Objective ◽

Cytochalasin D ◽

Inflammatory Signaling ◽

Macrophage Population ◽

Bronchoalveolar Fluid

Microparticles are a newly recognized class of mediators in the pathophysiology of lung inflammation and injury, but little is known about the factors that regulate their accumulation and clearance. The primary objective of our study was to determine whether alveolar macrophages engulf microparticles and to elucidate the mechanisms by which this occurs. Alveolar microparticles were quantified in bronchoalveolar fluid of mice with lung injury induced by LPS and hydrochloric acid. Microparticle numbers were greatest at the peak of inflammation and declined as inflammation resolved. Isolated, fluorescently labeled particles were placed in culture with macrophages to evaluate ingestion in the presence of endocytosis inhibitors. Ingestion was blocked with cytochalasin D and wortmannin, consistent with a phagocytic process. In separate experiments, mice were treated intratracheally with labeled microparticles, and their uptake was assessed though microscopy and flow cytometry. Resident alveolar macrophages, not recruited macrophages, were the primary cell-ingesting microparticles in the alveolus during lung injury. In vitro, microparticles promoted inflammatory signaling in LPS primed epithelial cells, signifying the importance of microparticle clearance in resolving lung injury. Microparticles were found to have phosphatidylserine exposed on their surfaces. Accordingly, we measured expression of phosphatidylserine receptors on macrophages and found high expression of MerTK and Axl in the resident macrophage population. Endocytosis of microparticles was markedly reduced in MerTK-deficient macrophages in vitro and in vivo. In conclusion, microparticles are released during acute lung injury and peak in number at the height of inflammation. Resident alveolar macrophages efficiently clear these microparticles through MerTK-mediated phagocytosis.

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Inhibition of ERRα Aggravates Sepsis-Induced Acute Lung Injury in Rats via Provoking Inflammation and Oxidative Stress

Oxidative Medicine and Cellular Longevity ◽

10.1155/2020/2048632 ◽

2020 ◽

Vol 2020 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Wenfang Xia ◽

Zhou Pan ◽

Huanming Zhang ◽

Qingshan Zhou ◽

Yu Liu

Keyword(s):

Oxidative Stress ◽

Acute Lung Injury ◽

Lung Injury ◽

Cecal Ligation ◽

Endothelial Permeability ◽

Inflammatory Factors ◽

Inflammatory Factor ◽

Junction Protein ◽

And Oxidative Stress

Inflammation and oxidative stress are critical pathologies that contribute to sepsis-induced acute lung injury (ALI). This study investigated the regulatory role of estrogen-related receptor alpha (ERRα) in an experimental model of sepsis-induced ALI. In vivo, a cecal ligation and puncture- (CLP-) induced ALI model was established in anesthetized rats. Animals were then randomly assigned to receive an intraperitoneal injection of vehicle or ERRα inverse agonist (XCT-790, 2.5 mg/kg). Administration of XCT-790 significantly aggravated a sepsis-induced increase in pathological damage of lung tissues, lung endothelial permeability, myeloperoxidase (MPO) activity in lung tissues, production of serum inflammatory factors, and inflammatory cell accumulation in bronchoalveolar lavage fluid. In addition, XCT-790 treatment exacerbated a CLP-induced decrease in lung superoxide dismutase and an increase in lung malondialdehyde levels. In vitro, the exposure of rat pulmonary microvascular endothelial cells (PMVECs) to lipopolysaccharide (LPS) resulted in increased endothelial permeability and reduced expression of tight junction protein ZO-1, Occludin, JAM-A, and adherens junction protein VE-cadherin, which were further deteriorated by knockdown of ERRα. In addition, LPS-triggered inflammatory factor production and increase in the expression of phosphorylated IκBα and NF-κB p65 were also exacerbated by silencing ERRα gene. Meanwhile, knockdown of ERRα dramatically promoted LPS-activated mitochondrial reactive oxygen species production and LPS-induced downregulation of Sirt3 protein levels in rat PMVECs. Taken together, our present study provides evidences that ERRα functions as a novel negative modulator of sepsis-induced ALI in rats. The underlying mechanisms responsible for ERRα-elicited effects are largely dependent on the regulation of inflammatory response and oxidative stress.

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