scholarly journals Inducible Lung Epithelial Resistance Requires Multisource Reactive Oxygen Species Generation To Protect against Viral Infections

mBio ◽  
2018 ◽  
Vol 9 (3) ◽  
Author(s):  
Carson T. Kirkpatrick ◽  
Yongxing Wang ◽  
Miguel M. Leiva Juarez ◽  
Pooja Shivshankar ◽  
Jezreel Pantaleón García ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Epithelial Cells ◽  
Viral Infections ◽  
Type I Interferon ◽  
Reactive Oxygen ◽  
Lung Epithelial Cells ◽  
Type I ◽  
Oxygen Species ◽  
Inducible Resistance ◽  
Lung Epithelial

ABSTRACTViral pneumonias cause profound worldwide morbidity, necessitating novel strategies to prevent and treat these potentially lethal infections. Stimulation of intrinsic lung defenses via inhalation of synergistically acting Toll-like receptor (TLR) agonists protects mice broadly against pneumonia, including otherwise-lethal viral infections, providing a potential opportunity to mitigate infectious threats. As intact lung epithelial TLR signaling is required for the inducible resistance and as these cells are the principal targets of many respiratory viruses, the capacity of lung epithelial cells to be therapeutically manipulated to function as autonomous antiviral effectors was investigated. Our work revealed that mouse and human lung epithelial cells could be stimulated to generate robust antiviral responses that both reduce viral burden and enhance survival of isolated cells and intact animals. The antiviral protection required concurrent induction of epithelial reactive oxygen species (ROS) from both mitochondrial and dual oxidase sources, although neither type I interferon enrichment nor type I interferon signaling was required for the inducible protection. Taken together, these findings establish the sufficiency of lung epithelial cells to generate therapeutically inducible antiviral responses, reveal novel antiviral roles for ROS, provide mechanistic insights into inducible resistance, and may provide an opportunity to protect patients from viral pneumonia during periods of peak vulnerability.IMPORTANCEViruses are the most commonly identified causes of pneumonia and inflict unacceptable morbidity, despite currently available therapies. While lung epithelial cells are principal targets of respiratory viruses, they have also been recently shown to contribute importantly to therapeutically inducible antimicrobial responses. This work finds that lung cells can be stimulated to protect themselves against viral challenges, even in the absence of leukocytes, both reducing viral burden and improving survival. Further, it was found that the protection occurs via unexpected induction of reactive oxygen species (ROS) from spatially segregated sources without reliance on type I interferon signaling. Coordinated multisource ROS generation has not previously been described against viruses, nor has ROS generation been reported for epithelial cells against any pathogen. Thus, these findings extend the potential clinical applications for the strategy of inducible resistance to protect vulnerable people against viral infections and also provide new insights into the capacity of lung cells to protect against infections via novel ROS-dependent mechanisms.

scholarly journals High Glucose Promotes Tumor Invasion and Increases Metastasis-Associated Protein Expression in Human Lung Epithelial Cells by Upregulating Heme Oxygenase-1 via Reactive Oxygen Species or the TGF-β1/PI3K/Akt Signaling Pathway

2015 ◽  
Vol 35 (3) ◽  
pp. 1008-1022 ◽  
Author(s):  
Xiaowen Kang ◽  
Fanwu Kong ◽  
Xiaomei Wu ◽  
Yeping Ren ◽  
Shijie Wu ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Epithelial Cells ◽  
Protein Expression ◽  
Human Lung ◽  
Reactive Oxygen ◽  
Lung Epithelial Cells ◽  
Oxygen Species ◽  
Lung Epithelial ◽  
Tgf Β1 ◽  
Human Lung Epithelial Cells

Background: Growing evidence indicates that heme oxygenase-1 (HO-1) is up-regulated in malignancies and subsequently alters tumor aggressiveness and various cancer-related factors, such as high glucose (HG) levels. HO-1 expression can be induced when glucose concentrations are above 25 mM; however, the role of HO-1 in lung cancer patients with diabetes remains unknown. Therefore, in this study we investigated the promotion of tumor cell invasion and the expression of metastasis-associated proteins by inducing the up-regulation of HO-1 expression by HG treatment in A549 human lung epithelial cells. Methods: The expression of HO-1and metastasis-associated protein expression was explored by western blot analysis. HO-1 enzymatic activity, reactive oxygen species (ROS) production and TGF-β1 production were examined by ELISA. Invasiveness was analyzed using a Transwell chamber. Results: HG treatment of A549 cells induced an increase in HO-1 expression, which was mediated by the HG-induced generation of reactive oxygen species (ROS) and transforming growth factor-β1 (TGF-β1) in a concentration- and time-dependent manner. Following the increase in HO-1 expression, the enzymatic activity of HO-1 also increased in HG-treated cells. Pretreatment with N-acetyl-L-cysteine (NAC) or with phosphatidylinositol 3-kinase (PI3K)/Akt inhibitors attenuated the HG-induced increase in HO-1 expression. HG treatment of A549 cells enhanced the invasion potential of these cells, as shown with a Transwell assay, and increased metastasis-associated protein expression. However, HO-1 siRNA transfection significantly decreased these capabilities. Conclusion: this study is the first to demonstrate that HG treatment of A549 human lung epithelial cells promotes tumor cell invasion and increases metastasis-associated protein expression by up-regulating HO-1 expression via ROS or the TGF-β1/PI3K/Akt signaling pathway.

scholarly journals Inducible Lung Epithelial Resistance Requires Multisource Reactive Oxygen Species Generation to Protect against Bacterial Infections

2018 ◽  
Author(s):  
Hayden H. Ware ◽  
Vikram V. Kulkarni ◽  
Yongxing Wang ◽  
Miguel Leiva Juarez ◽  
Carson T. Kirkpatrick ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Bacterial Infections ◽  
Reactive Oxygen Species Generation ◽  
Reactive Oxygen ◽  
Lung Epithelial Cells ◽  
Oxygen Species ◽  
Ros Scavenging ◽  
Bacterial Killing ◽  
Inducible Resistance ◽  
Lung Epithelial

ABSTRACTPneumonia remains a global health threat, in part due to expanding categories of susceptible individuals and increasing prevalence of antibiotic resistant pathogens. However, therapeutic stimulation of the lungs’ mucosal defenses by inhaled exposure to a synergistic combination of Toll-like receptor (TLR) agonists known as Pam2-ODN promotes mouse survival of pneumonia caused by a wide array of pathogens. This inducible resistance to pneumonia relies on intact lung epithelial TLR signaling, and inducible protection against viral pathogens has recently been shown to require increased production of epithelial reactive oxygen species (ROS) from multiple epithelial ROS generators. To determine whether similar mechanisms contribute to inducible antibacterial responses, the current work investigates the role of ROS in therapeutically-stimulated protection against Pseudomonas aerugnosa challenges. Inhaled Pam2-ODN treatment one day before infection prevented hemorrhagic lung cytotoxicity and mouse death in a manner that correlated with reduction in bacterial burden. The bacterial killing effect of Pam2-ODN was recapitulated in isolated mouse and human lung epithelial cells, and the protection correlated with inducible epithelial generation of ROS. Scavenging or targeted blockade of ROS production from either dual oxidase or mitochondrial sources resulted in near complete loss of Pam2-ODN-induced bacterial killing, whereas deficiency of induced antimicrobial peptides had little effect. These findings support a central role for multisource epithelial ROS in inducible resistance against bacterial pathogens and provide mechanistic insights into means to protect vulnerable patients against lethal infections.

scholarly journals Lung Epithelial Regulation of BCL2 Related Protein A1 (BCL2A1) by Coronaviruses (SARS-CoV) and Type I Interferon Signaling

2021 ◽  
Author(s):  
Ramana Chilakamarti
Keyword(s):  
Epithelial Cells ◽  
Human Lung ◽  
Type I Interferon ◽  
Respiratory Viruses ◽  
Lung Epithelial Cells ◽  
Type I ◽  
Related Protein ◽  
Interferon Signaling ◽  
Lung Epithelial ◽  
Human Lung Epithelial Cells

Highly pathogenic respiratory viruses such as 1918 influenza (HIN1) and coronavirus (SARS-CoV-2) induce significant lung injury with diffuse alveolar damage, capillary leak, and extensive cell death resulting in acute respiratory distress syndrome (ARDS). Direct effects of the virus, as well as host immune response such as proinflammatory cytokine production, contribute to programmed cell death or apoptosis. Alveolar lung epithelial type II (AT2) cells play a major role in the clearance of respiratory viruses, secretion of surfactant proteins and antimicrobial substances into the bronchoalveolar fluid as well as repair of lung injury. Gene expression in AT2 cells is regulated in a tissue and cell-specific manner and in a temporal fashion. The availability of tissue and cell-specific RNA datasets in Human Protein Atlas led to the identification of localized expression patterns of BCL-2 family members such as BCL2 related protein A1 (BCL2A1) in AT2 cells and immune cells of the lung. BCL2A1 expression was regulated by multiple stimuli including Toll-like receptor (TLR) ligands, interferons (IFNs), inflammatory cytokines, and inhibited by the steroid dexamethasone. In this study, regulation of BCL2A1 gene expression in human lung epithelial cells by several respiratory viruses and type I interferon signaling was investigated. SARS-CoV-2 infection significantly induced BCL2A1 expression in human lung epithelial cells within 24 hours that required the expression of Angiotensin-converting enzyme 2 (ACE2). BCL2A1 mRNA induction by SARS-CoV-2 was correlated with the induced expression of IFN-β and IFN-regulated transcription factor mRNA. BCL2A1 was induced by IFN-β treatment or by infection with influenza virus lacking the non-structural protein1(NS1) in NHBE cells. Furthermore, bioinformatics revealed that a subset of BCL-2 family members involved in the control of apoptosis and transcription such as BCL2A1, BCL2L14, BCL3, and BCL6 were regulated in the lung epithelial cells by coronaviruses and in the lung tissue samples of COVID-19 patients. Transcriptomic data also suggested that these genes were differentially regulated by the steroid drug dexamethasone.

scholarly journals Cyclic mechanical strain increases reactive oxygen species production in pulmonary epithelial cells

2005 ◽  
Vol 289 (5) ◽  
pp. L834-L841 ◽  
Author(s):  
Kenneth E. Chapman ◽  
Scott E. Sinclair ◽  
Daming Zhuang ◽  
Aviv Hassid ◽  
Leena P. Desai ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Epithelial Cells ◽  
Cell Line ◽  
Primary Cultures ◽  
Reactive Oxygen ◽  
Lung Epithelial Cells ◽  
Alveolar Type ◽  
Ros Production ◽  
Oxygen Species ◽  
Type Ii

Overdistention of lung tissue during mechanical ventilation may be one of the factors that initiates ventilator-induced lung injury (VILI). We hypothesized that cyclic mechanical stretch (CMS) of the lung epithelium is involved in the early events of VILI through the production of reactive oxygen species (ROS). Cultures of an immortalized human airway epithelial cell line (16HBE), a human alveolar type II cell line (A549), and primary cultures of rat alveolar type II cells were cyclically stretched, and the production of superoxide (O2−) was measured by dihydroethidium fluorescence. CMS stimulated increased production of O2− after 2 h in each type of cell. 16HBE cells exhibited no significant stimulation of ROS before 2 h of CMS (20% strain, 30 cycles/min), and ROS production returned to control levels after 24 h. Oxidation of glutathione (GSH), a cellular antioxidant, increased with CMS as measured by a decrease in the ratio of the reduced GSH level to the oxidized GSH level. Strain levels of 10% did not increase O2− production in 16HBE cells, whereas 15, 20, and 30% significantly increased generation of O2−. Rotenone, a mitochondrial complex I inhibitor, partially abrogated the stretch-induced generation of O2− after 2 h CMS in 16HBE cells. NADPH oxidase activity was increased after 2 h of CMS, contributing to the production of O2−. Increased ROS production in lung epithelial cells in response to elevated stretch may contribute to the onset of VILI.

Superoxide dismutase moderates basal and induced bacterial adherence and interleukin-8 expression in airway epithelial cells

2004 ◽  
Vol 287 (6) ◽  
pp. L1199-L1206 ◽  
Author(s):  
Yuko Arita ◽  
Ansamma Joseph ◽  
Hshi-Chi Koo ◽  
Yuchi Li ◽  
Thomas A. Palaia ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Superoxide Dismutase ◽  
Epithelial Cells ◽  
A549 Cells ◽  
Reactive Oxygen ◽  
Bacterial Adherence ◽  
Interleukin 8 ◽  
Lung Epithelial Cells ◽  
Oxygen Species ◽  
Airway Epithelial

Bacterial infection of the tracheobronchial tree is a frequent, serious complication in patients receiving treatment with oxygen and mechanical ventilation, resulting in increased morbidity and mortality. Using human airway epithelial cell culture models, we examined the effect of hyperoxia on bacterial adherence and the expression of interleukin-8 (IL-8), an important mediator involved in the inflammatory process. A 24-h exposure to 95% O2increased Pseudomonas aeruginosa (PA) adherence 57% in A549 cells ( P < 0.01) and 115% in 16HBE cells ( P < 0.01) but had little effect on Staphylococcus aureus (SA) adherence. Exposure to hyperoxia, followed by a 1-h incubation with SA, further enhanced PA adherence ( P < 0.01), suggesting that hyperoxia and SA colonization may enhance the susceptibility of lung epithelial cells to gram-negative infections. IL-8 expression was also increased in cells exposed to both hyperoxia and PA. Stable or transient overexpression of manganese superoxide dismutase reduced both basal and stimulated levels of PA adherence and IL-8 levels in response to exposure to either hyperoxia or PA. These data indicate that hyperoxia increases susceptibility to infection and that the pathways are mediated by reactive oxygen species. Therapeutic intervention strategies designed to prevent accumulation of intracellular reactive oxygen species may reduce opportunistic pulmonary infections.

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