Human alveolar epithelial cells induce nitric oxide synthase‐2 expression in alveolar macrophages

Patients with interstitial lung diseases, such as idiopathic pulmonary fibrosis (IPF) and bronchopulmonary dysplasia (BPD), suffer from lung fibrosis secondary to myofibroblast-mediated excessive ECM deposition and destruction of lung architecture. Transforming growth factor (TGF)-β1 induces epithelial-mesenchymal transition (EMT) of alveolar epithelial cells (AEC) to myofibroblasts both in vitro and in vivo. Inhaled nitric oxide (NO) attenuates ECM accumulation, enhances lung growth, and decreases alveolar myofibroblast number in experimental models. We therefore hypothesized that NO attenuates TGF-β1-induced EMT in cultured AEC. Studies of the capacity for endogenous NO production in AEC revealed that endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) are expressed and active in AEC. Total NOS activity was 1.3 pmol·mg protein−1·min−1 with 67% derived from eNOS. TGF-β1 (50 pM) suppressed eNOS expression by more than 60% and activity by 83% but did not affect iNOS expression or activity. Inhibition of endogenous NOS with l-NAME led to spontaneous EMT, manifested by increased α-smooth muscle actin (α-SMA) expression and a fibroblast-like morphology. Provision of exogenous NO to TGF-β1-treated AEC decreased stress fiber-associated α-SMA expression and decreased collagen I expression by 80%. NO-treated AEC also retained an epithelial morphology and expressed increased lamellar protein, E-cadherin, and pro-surfactant protein B compared with those treated with TGF-β alone. These findings indicate that NO serves a critical role in preserving an epithelial phenotype and in attenuating EMT in AEC. NO-mediated regulation of AEC fate may have important implications in the pathophysiology and treatment of diseases such as IPF and BPD.

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Induction of nitric oxide synthase expression by lipopolysaccharide is mediated by calcium-dependent PKCα-β1 in alveolar epithelial cells

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00295.2012 ◽

2013 ◽

Vol 305 (2) ◽

pp. L175-L184 ◽

Cited By ~ 9

Author(s):

Émilie Boncoeur ◽

Guillaume F. Bouvet ◽

Francis Migneault ◽

Valérie Tardif ◽

Pasquale Ferraro ◽

...

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Epithelial Cells ◽

Purinergic Receptor ◽

Alveolar Epithelial Cells ◽

Inos Mrna ◽

Alveolar Epithelial ◽

Mrna Induction ◽

Dependent Process ◽

Oxide Synthase

Nitric oxide (NO) plays an important role in innate host defense and inflammation. In response to infection, NO is generated by inducible nitric oxide synthase (iNOS), a gene product whose expression is highly modulated by different stimuli, including lipopolysaccharide (LPS) from gram-negative bacteria. We reported recently that LPS from Pseudomonas aeruginosa altered Na+ transport in alveolar epithelial cells via a suramin-dependent process, indicating that LPS activated a purinergic response in these cells. To further study this question, in the present work, we tested whether iNOS mRNA and protein expression were modulated in response to LPS in alveolar epithelial cells. We found that LPS induced a 12-fold increase in iNOS mRNA expression via a transcription-dependent process in these cells. iNOS protein, NO, and nitrotyrosine were also significantly elevated in LPS-treated cells. Ca2+ chelation and protein kinase C (PKCα-β1) inhibition suppressed iNOS mRNA induction by LPS, implicating Ca2+-dependent PKC signaling in this process. LPS evoked a significant increase of extracellular ATP. Because PKC activation is one of the signaling pathways known to mediate purinergic signaling, we evaluated the hypothesis that iNOS induction was ATP dependent. Although high suramin concentration inhibited iNOS mRNA induction, the process was not ATP dependent, since specific purinergic receptor antagonists could not inhibit the process. Altogether, these findings demonstrate that iNOS expression is highly modulated in alveolar epithelial cells by LPS via a Ca2+/PKCα-β1 pathway independent of ATP signaling.

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Interplay Between Cytokine-Induced and Cyclic Equibiaxial Deformation-Induced Nitric Oxide Production and Metalloproteases Expression in Human Alveolar Epithelial Cells

Cellular and Molecular Bioengineering ◽

10.1007/s12195-009-0092-4 ◽

2009 ◽

Vol 2 (4) ◽

pp. 615-624 ◽

Cited By ~ 8

Author(s):

Hemang Patel ◽

Soonjo Kwon

Keyword(s):

Nitric Oxide ◽

Epithelial Cells ◽

Alveolar Epithelial Cells ◽

Nitric Oxide Production ◽

Alveolar Epithelial ◽

Oxide Production ◽

Human Alveolar Epithelial Cells

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Viral Replication and Innate Host Responses in Primary Human Alveolar Epithelial Cells and Alveolar Macrophages Infected with Influenza H5N1 and H1N1 Viruses

Journal of Virology ◽

10.1128/jvi.02200-10 ◽

2011 ◽

Vol 85 (14) ◽

pp. 6844-6855 ◽

Cited By ~ 97

Author(s):

W. C. L. Yu ◽

R. W. Y. Chan ◽

J. Wang ◽

E. A. Travanty ◽

J. M. Nicholls ◽

...

Keyword(s):

Epithelial Cells ◽

Viral Replication ◽

Alveolar Macrophages ◽

Alveolar Epithelial Cells ◽

Host Responses ◽

Alveolar Epithelial ◽

Influenza H5n1 ◽

Human Alveolar Epithelial Cells

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Rifampin Augments Cytokine-Induced Nitric Oxide Production in Human Alveolar Epithelial Cells

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.50.1.396-398.2006 ◽

2006 ◽

Vol 50 (1) ◽

pp. 396-398 ◽

Cited By ~ 14

Author(s):

Yael Yuhas ◽

Eva Berent ◽

Hila Ovadiah ◽

Inbar Azoulay ◽

Shai Ashkenazi

Keyword(s):

Nitric Oxide ◽

Immune Response ◽

Alveolar Epithelial Cells ◽

Nitric Oxide Production ◽

Alveolar Cells ◽

Alveolar Epithelial ◽

Oxide Production ◽

Oxide Synthase ◽

Inducible Nitric Oxide ◽

Human Alveolar Epithelial Cells

ABSTRACT Rifampin increased nitric oxide production and inducible nitric oxide synthase expression in alveolar cells stimulated with cytokines. Nitric oxide concentrations after induction with cytokines, cytokines with 10 μg/ml rifampin, and cytokines with 50 μg/ml rifampin were 3.2, 4.5, and 8.8 μM, respectively (P < 0.02 versus cytokines alone). This indicates that rifampin modulates the immune response.

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