Hypoxia-induced modifications in plasma membranes and lipid microdomains in A549 cells and primary human alveolar cells

Abstract Objectives Thrombin generation is crucial to the regulation of hemostasis and thrombosis and is essential to the pathogenesis of cardiovascular disease and venous thrombosis. Pulmonary embolism is a blockage in one of the pulmonary arteries in your lung caused by blood clots due to risk factors including tobacco use. Astragalin (kaempferol 3-O-glucoside) is a flavonoid present in persimmon leaves and green tea seeds and exhibits diverse activities such as asthma and obstructive pulmonary disease. This study investigated that astragalin encumbered pulmonary inflammation caused by cigarette smoking-induced embolism. Methods Pulmonary embolism was evoked through exposure of BALB/c mice to cigarette smoke for 30 min, five days a week for eight weeks. Mice were orally administrated with 10 or 20 mg/kg astragalin for 8 weeks. For the in vitro studies, 10 U/ml thrombin was loaded to alveolar epithelial A549 cells in the absence and presence of 1–20 μM astragalin. Results Oral supplementation of astragalin reduced tissue factor and urokinase-type plasminogen activator elevated in cigarette smoking-exposed lungs. In addition, 1–20 μM astragalin attenuated the induction of protease activated receptor-1 known as coagulation factor II (thrombin) receptor-like-1, in 10 U/ml thrombin-loaded alveolar epithelial cells. Astragalin curtailed induction of the inflammatory mediators of cyclooxygenase-2, intercellular adhesion molecule-1 and inducible nitric oxide synthase in alveolar cells subjected to thrombin. Furthermore, astragalin inhibited inflammatory signaling entailing MAPK/ERK pathway. Conclusions Astragalin may be a potential agent alleviating pulmonary inflammation induced by cigarette smoking-induced embolism. Funding Sources This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2019R1A6A3A01094891).

Aesculetin Attenuates Pulmonary Fibrosis Induced by Close Contact of Macrophages with Alveolar Epithelial Cells

Current Developments in Nutrition ◽

10.1093/cdn/nzaa068_016 ◽

2020 ◽

Vol 4 (Supplement_2) ◽

pp. 1531-1531

Author(s):

Suyeon Oh ◽

Young-Hee Kang

Keyword(s):

Epithelial Cells ◽

Pulmonary Fibrosis ◽

A549 Cells ◽

Conditioned Media ◽

Alveolar Epithelial Cells ◽

Alveolar Cells ◽

Mesenchymal Transition ◽

Alveolar Epithelial ◽

Funding Sources ◽

E Cadherin

Abstract Objectives Pulmonary fibrosis is a disease in which lung tissues become fibrous and causes severe respiratory disturbances. Various stimuli induce infiltration of macrophages to the respiratory tract. These macrophages secrete various inflammatory cytokines leading to development of pulmonary fibrosis via epithelial–mesenchymal transition (EMT) process. Aesculetin, a major component of Sancho tree and Chicory, is known to have antioxidant and anti-inflammatory effects in the vascular and immune system. Methods Human alveolar basal epithelial A549 cells were cultured in conditioned media of THP-1 monocyte-derived macrophages for 24 h. Aesculetin at the concentrations of 1–20 μM did not show cytotoxicity of A549 cells. Alveolar epithelial cells were incubated with interleukin (IL)-8. Western blotting examined EMT-associated fibrotic proteins from A549 cell lysates. Matrix metalloproteinase (MMP) activity was measured with gelatin zymography. In addition, inflammation- and fibrosis-related cytokines were measured by using ELISA kits. Results The epithelial markers of E-cadherin and ZO-1 were reduced in cells exposed to macrophage-conditioned media containing IL-8 and TNF-α. Macrophage-conditioned media enhanced expression of the mesenchymal fibrotic markers of α-smooth muscle actin (α-SMA), vimentin and fibronectin, and the fibrotic proteins of collagen I and collagen IV were enhanced. However, ≥10 μM aesculetin reciprocally manipulated the expression levels of these proteins of A549 cells. In addition, macrophage-conditioned media enhanced the expression and activity of MT1-MMP, MMP-2 and MMP-9. In contrast, the expression of tissue inhibitor of metalloproteinases (TIMP)-1 and TIMP-2 were reduced by exposure of alveolar cells to conditioned media. Proinflammatory and chemotactic IL-8 reduced E-cadherin and conversely enhanced N-cadherin and α-SMA in A549 cells, which was reciprocally modulated by ≥ 10 μM aesculetin. These results demonstrate that aesculetin may ameliorate EMT-associated pulmonary fibrosis caused by contact of blood-derived macrophages and alveolar cells. Conclusions Aesculetin maybe a promising agent treating progressive pulmonary disorders owing to macrophage-mediated inflammation. Funding Sources No funding sources to report.

Effects of TNF-α and IL-1β on iron metabolism by A549 cells and influence on cytotoxicity

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1999.277.2.l257 ◽

1999 ◽

Vol 277 (2) ◽

pp. L257-L263 ◽

Cited By ~ 5

Author(s):

Igor M. Smirnov ◽

Kirstin Bailey ◽

Carol H. Flowers ◽

Ned W. Garrigues ◽

Lewis J. Wesselius

Keyword(s):

Cell Death ◽

Lactate Dehydrogenase ◽

Iron Metabolism ◽

Iron Uptake ◽

A549 Cells ◽

Receptor Expression ◽

Alveolar Cells ◽

Lactate Dehydrogenase Release ◽

Ferritin Synthesis ◽

Tnf Α

Extracellular iron, which is predominantly bound by transferrin, is present in low concentrations within alveolar structures, and concentrations are increased in various pulmonary disorders. Iron accumulation by cells can promote oxidative injury. However, the synthesis of ferritin stimulated by metal exposure for intracellular iron storage is normally protective. The cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-1β may alter iron metabolism by alveolar cells. In this study, we assessed the effects of TNF-α and IL-1β on iron metabolism with a cell line with properties of type 2 alveolar epithelial cells (A549) exposed to non-transferrin-bound (NTBI; FeSO4) or transferrin-bound (TBI) iron. In addition, we assessed the cytotoxicity of these exposures by measuring the cell accumulation of malondialdehyde (MDA), a product of lipid peroxidation, and cell death (MTT assay and lactate dehydrogenase release). A549 cells treated with NTBI or TBI in concentrations up to 40 μM accumulated iron and synthesized predominantly L-type ferritin without accumulation of MDA or cell death. Treatment of A549 cells with TNF-α (20 ng) or IL-1β (20 ng) decreased cell transferrin-receptor expression and induced synthesis of H-type ferritin. TNF-α and IL-1β decreased the uptake of TBI; however, the uptake of NTBI was increased. Both cytokines enhanced total ferritin synthesis (H plus L types) in response to iron treatments due to enhanced synthesis of H-type ferritin. Coexposure to TNF-α and NTBI, but not to TBI, induced MDA accumulation and greater cytotoxicity (MTT and lactate dehydrogenase release) than TNF-α alone. These findings indicate that TNF-α and IL-1β modulate iron uptake by A549 cells, with differing effects on TBI and NTBI, as well as on H-ferritin synthesis. Enhanced iron uptake induced by TNF-α and NTBI was also associated with increased cytotoxicity to A549 cells.

Aesculetin Inhibits Pulmonary Fibrosis by Epithelial-to-mesenchymal Transition(EMT) in a Alveolar Epithelial Cell (P06-068-19)

Current Developments in Nutrition ◽

10.1093/cdn/nzz031.p06-068-19 ◽

2019 ◽

Vol 3 (Supplement_1) ◽

Author(s):

Su Yeon Oh ◽

Young-Hee Kang

Keyword(s):

Pulmonary Fibrosis ◽

Epithelial To Mesenchymal Transition ◽

Epithelial Mesenchymal Transition ◽

Alveolar Epithelial Cell ◽

Smooth Muscle Actin ◽

Pulmonary Inflammation ◽

A549 Cells ◽

Conditioned Media ◽

Alveolar Cells ◽

Mesenchymal Transition

Abstract Objectives Pulmonary fibrosis is a disease in which lung tissues become fibrous and causes severe respiratory disturbances. Various stimuli induce infiltration of macrophages to the respiratory tract. These macrophages secrete various cytokines leading to development of pulmonary fibrosis. Aesculetin, a major component of Sancho tree and Chicory, is known to have antioxidant and anti-inflammatory effects in the vascular and immune system. However, its effect on pulmonary fibrosis has been poorly understood. The current study investigated that aesculetin inhibited pulmonary fibrosis caused by infiltration of monocyte-derived macrophages. Methods To differentiate to monocyte-derived macrophages, THP-1 human mononuclear cell line was treated with 50 ng/ml phorbol myristate acetate (PMA) for 24 h. Culture conditioned media were harvested from macrophages cultured in the absence of PMA for 24 h. A549 human alveolar basal epithelial cells were cultured in the conditioned media for 24 h to induce alveolar fibrosis. Epithelial–mesenchymal transition (EMT)-associated fibrotic proteins were measured with Western blotting from A549 cell lysates. Results Aesculetin at the concentrations of 1–20 μM did not show any toxicity of A549 cells, evidence by MTT assay. When A549 cells were treated with conditioned media from monocyte-derived macrophages, the expression of mesenchymal fibrotic proteins of α-smooth muscle actin and fibronectin was highly enhanced. In contrast, ≥10 μM aesculetin inhibited the induction of these proteins of A549 cells. The expression of E-cadherin and Zonula occludens-1 was reduced in cells supplemented with conditioned media, while aesculetin promoted these epithelial phenotypic proteins in conditioned media-exposed alveolar cells. Conclusions These results demonstrate that aesculetin may ameliorate EMT-associated alveolar fibrosis caused by monocyte-derived macrophages infiltrated into the alveoli. Therefore, Aesculetin maybe a promising agent treating progressive pulmonary disorders owing to pulmonary inflammation. Funding Sources This work (Grants No. C0501612) was supported by project for Cooperative R&D between Industry, Academy, and Research Institute funded Korea Ministry of SMEs and Startups in 20.

Compositional changes in lipid microdomains of air-blood barrier plasma membranes in pulmonary interstitial edema

Journal of Applied Physiology ◽

10.1152/japplphysiol.00208.2003 ◽

2003 ◽

Vol 95 (4) ◽

pp. 1446-1452 ◽

Cited By ~ 29

Author(s):

Paola Palestini ◽

Chiara Calvi ◽

Elena Conforti ◽

Rossella Daffara ◽

Laura Botto ◽

...

Keyword(s):

Plasma Membrane ◽

Lipid Rafts ◽

Plasma Membranes ◽

Membrane Surface ◽

Basement Membranes ◽

Interstitial Edema ◽

Pulmonary Tissue ◽

Lipid Microdomains ◽

Aquaporin 1 ◽

Compositional Changes

We evaluated in anesthetized rabbits the compositional changes of plasmalemmal lipid microdomains from lung tissue samples after inducing pulmonary interstitial edema (0.5 ml/kg for 3 h, leading to ∼5% increase in extravascular water). Lipid microdomains (lipid rafts and caveolae) were present in the detergent-resistant fraction (DRF) obtained after discontinuous sucrose density gradient. DRF was enriched in caveolin-1, flotillin, aquaporin-1, GM1, cholesterol, sphingomyelin, and phosphatidylserine, and their contents significantly increased in interstitial edema. The higher DRF content in caveolin, flotillin, and aquaporin-1 and of the ganglioside GM1 suggests an increase both in caveolar domains and in lipid rafts, respectively. Compositional changes could be ascribed to endothelial and epithelial cells that provide most of plasma membrane surface area in the air-blood barrier. Alterations in lipid components in the plasma membrane may reflect rearrangement of floating lipid platforms within the membrane and/or lipid translocation from intracellular stores. Lipid traffic could be stimulated by the marked increase in hydraulic interstitial pressure after initial water accumulation, from approximately -10 to 5 cmH2O, due to the low compliance of the pulmonary tissue, in particular in the basement membranes and in the interfibrillar substance. Compositional changes in lipid microdomains represent a sign of cellular activation and suggest the potential role of mechanotransduction in response to developing interstitial edema.

The Efficiency of the Translocation of Mycobacterium tuberculosis across a Bilayer of Epithelial and Endothelial Cells as a Model of the Alveolar Wall Is a Consequence of Transport within Mononuclear Phagocytes and Invasion of Alveolar Epithelial Cells

Infection and Immunity ◽

10.1128/iai.70.1.140-146.2002 ◽

2002 ◽

Vol 70 (1) ◽

pp. 140-146 ◽

Cited By ~ 105

Author(s):

Luiz E. Bermudez ◽

Felix J. Sangari ◽

Peter Kolonoski ◽

Mary Petrofsky ◽

Joseph Goodman

Keyword(s):

Endothelial Cells ◽

Mycobacterium Tuberculosis ◽

Epithelial Cells ◽

A549 Cells ◽

Mononuclear Phagocytes ◽

Alveolar Epithelial Cells ◽

Alveolar Wall ◽

Alveolar Cells ◽

Initial Inoculum ◽

Alveolar Epithelial

ABSTRACT The mechanism(s) by which Mycobacterium tuberculosis crosses the alveolar wall to establish infection in the lung is not well known. In an attempt to better understand the mechanism of translocation and create a model to study the different stages of bacterial crossing through the alveolar wall, we established a two-layer transwell system. M. tuberculosis H37Rv was evaluated regarding the ability to cross and disrupt the membrane. M. tuberculosis invaded A549 type II alveolar cells with an efficiency of 2 to 3% of the initial inoculum, although it was not efficient in invading endothelial cells. However, bacteria that invaded A549 cells were subsequently able to be taken up by endothelial cells with an efficiency of 5 to 6% of the inoculum. When incubated with a bicellular transwell monolayer (epithelial and endothelial cells), M. tuberculosis translocated into the lower chamber with efficiency (3 to 4%). M. tuberculosis was also able to efficiently translocate across the bicellular layer when inside monocytes. Infected monocytes crossed the barrier with greater efficiency when A549 alveolar cells were infected with M. tuberculosis than when A549 cells were not infected. We identified two potential mechanisms by which M. tuberculosis gains access to deeper tissues, by translocating across epithelial cells and by traveling into the blood vessels within monocytes.

Effect of Hyperhomocysteinemia on a Murine Model of Smoke-Induced Pulmonary Emphysema.

10.21203/rs.3.rs-249722/v1 ◽

2021 ◽

Author(s):

Hiroshi Nakano ◽

Sumito Inoue ◽

Akira Igarashi ◽

Yoshikane Tokairin ◽

Keiko Yamauchi ◽

...

Keyword(s):

Vitamin B12 ◽

Er Stress ◽

Cigarette Smoke ◽

Pulmonary Emphysema ◽

A549 Cells ◽

Control Group ◽

Alveolar Cells ◽

Folate Supplementation ◽

Simultaneous Stimulation ◽

Smoking Susceptibility

Abstract Hyperhomocysteinemia (HHcy) was reported to enhance endoplasmic reticulum (ER) stress and subsequent apoptosis in several cells. However, the precise mechanisms of smoking susceptibility associated with HHcy has not been fully elucidated. This study included seven- to nine-week-old C57BL6 male mice induced with HHcy and were exposed to cigarette smoke (CS). A549 cells (human alveolar epithelial cell line) were cultured with homocysteine and were exposed to cigarette smoke extract (CSE) to observe cell viability and expression of proteins related to the ER stress. After 6 months of CS exposure, pulmonary emphysema was more severely induced in the group under the condition of HHcy compared to that in the control group. The apoptotic A549 cells increased as Hcy concentration increased and that was enhanced by CSE. Protein expression levels of ER stress markers were significantly increased after simultaneous stimulation. Notably, vitamin B12 and folate supplementation improved ER stress after simultaneous stimulation of A549 cells. HHcy exacerbated smoking-induced pulmonary emphysema and ER stress-induced alveolar cell apoptosis. ER stress in alveolar cells was reversed by vitamin B12 and folate supplementation, suggesting that HHcy could be the new therapeutic target to improve smoking susceptibility.

The Omega-3 Fatty Acid Docosahexaenoic Acid Modulates Inflammatory Mediator Release in Human Alveolar Cells Exposed to Bronchoalveolar Lavage Fluid of ARDS Patients

BioMed Research International ◽

10.1155/2015/642520 ◽

2015 ◽

Vol 2015 ◽

pp. 1-11 ◽

Cited By ~ 3

Author(s):

Paolo Cotogni ◽

Antonella Trombetta ◽

Giuliana Muzio ◽

Marina Maggiora ◽

Rosa Angela Canuto

Keyword(s):

Docosahexaenoic Acid ◽

Bronchoalveolar Lavage ◽

Bronchoalveolar Lavage Fluid ◽

Ex Vivo ◽

A549 Cells ◽

Lavage Fluid ◽

Mediator Release ◽

Omega 3 ◽

Alveolar Cells ◽

Cox 2

Background. This study investigated whether the 1 : 2 ω-3/ω-6 ratio may reduce proinflammatory response in human alveolar cells (A549) exposed to anex vivoinflammatory stimulus (bronchoalveolar lavage fluid (BALF) of acute respiratory distress syndrome (ARDS) patients).Methods. We exposed A549 cells to the BALF collected from 12 ARDS patients. After 18 hours, fatty acids (FA) were added as docosahexaenoic acid (DHA,ω-3) and arachidonic acid (AA,ω-6) in two ratios (1 : 2 or 1 : 7). 24 hours later, in culture supernatants were evaluated cytokines (TNF-α, IL-6, IL-8, and IL-10) and prostaglandins (PGE2and PGE3) release. The FA percentage content in A549 membrane phospholipids, content of COX-2, level of PPARγ, and NF-κB binding activity were determined.Results. The 1 : 2 DHA/AA ratio reversed the baseline predominance ofω-6 overω-3 in the cell membranes (P< 0.001). The proinflammatory cytokine release was reduced by the 1 : 2 ratio (P< 0.01 to <0.001) but was increased by the 1 : 7 ratio (P< 0.01). The 1 : 2 ratio reduced COX-2 and PGE2(P< 0.001) as well as NF-κB translocation into the nucleus (P< 0.01), while it increased activation of PPARγand IL-10 release (P< 0.001).Conclusion. This study demonstrated that shifting the FA supply fromω-6 toω-3 decreased proinflammatory mediator release in human alveolar cells exposed to BALF of ARDS patients.

Post-correlation on-lamella cryo-CLEM reveals the membrane architecture of lamellar bodies

Communications Biology ◽

10.1038/s42003-020-01567-z ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Steffen Klein ◽

Benedikt H. Wimmer ◽

Sophie L. Winter ◽

Androniki Kolovou ◽

Vibor Laketa ◽

...

Keyword(s):

Electron Microscopy ◽

Current Knowledge ◽

Electron Tomography ◽

Light And Electron Microscopy ◽

A549 Cells ◽

Airway Epithelial Cells ◽

Lamellar Bodies ◽

Membrane Structures ◽

Alveolar Cells ◽

Cryo Electron Tomography

AbstractLamellar bodies (LBs) are surfactant-rich organelles in alveolar cells. LBs disassemble into a lipid-protein network that reduces surface tension and facilitates gas exchange in the alveolar cavity. Current knowledge of LB architecture is predominantly based on electron microscopy studies using disruptive sample preparation methods. We established and validated a post-correlation on-lamella cryo-correlative light and electron microscopy approach for cryo-FIB milled cells to structurally characterize and validate the identity of LBs in their unperturbed state. Using deconvolution and 3D image registration, we were able to identify fluorescently labeled membrane structures analyzed by cryo-electron tomography. In situ cryo-electron tomography of A549 cells as well as primary Human Small Airway Epithelial Cells revealed that LBs are composed of membrane sheets frequently attached to the limiting membrane through “T”-junctions. We report a so far undescribed outer membrane dome protein complex (OMDP) on the limiting membrane of LBs. Our data suggest that LB biogenesis is driven by parallel membrane sheet import and by the curvature of the limiting membrane to maximize lipid storage capacity.