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Regulation of angiopoietin-2 secretion from human pulmonary microvascular endothelial cells

Lee, Ji Young; Linge, Helena M LU ; Ochani, Kanta; Lin, Ke and Miller, Edmund J (2016) In Lung 42(7). p.335-345
Abstract

INTRODUCTION: Sepsis is characterized by dysregulated systemic inflammation and cytokine storm. Angiopoietin-2 (Ang-2) is known to closely correlate with severity of sepsis-related acute lung injury and mortality. The aim of this study was to clarify the mechanisms involved in Ang-2 secretion to better understand the pathophysiology of sepsis.

MATERIALS AND METHODS: The concentration of Ang-2 was assessed in culture medium of pulmonary microvascular endothelial cells in the presence or absence of Gram-positive bacteria cell wall components [lipoteichoic acid (LTA) and peptidoglycan (PGN)] stimulation at different time points ranging from 15 minutes to 24 hours. Constitutive and LTA-PGN-stimulated Ang-2 level changes were also... (More)

INTRODUCTION: Sepsis is characterized by dysregulated systemic inflammation and cytokine storm. Angiopoietin-2 (Ang-2) is known to closely correlate with severity of sepsis-related acute lung injury and mortality. The aim of this study was to clarify the mechanisms involved in Ang-2 secretion to better understand the pathophysiology of sepsis.

MATERIALS AND METHODS: The concentration of Ang-2 was assessed in culture medium of pulmonary microvascular endothelial cells in the presence or absence of Gram-positive bacteria cell wall components [lipoteichoic acid (LTA) and peptidoglycan (PGN)] stimulation at different time points ranging from 15 minutes to 24 hours. Constitutive and LTA-PGN-stimulated Ang-2 level changes were also assessed after cells were pretreated with different pathway inhibitors for 1 hour.

RESULTS: Two distinctive mechanisms of Ang-2 secretion, constitutive and stimulated secretion, were identified. Constitutive secretion resulted in slow but continuous increase in Ang-2 in culture medium over time. It was regulated by 3'5'-cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA)-Ca(2+) and nitric oxide (NO)-3'5'-cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG)-Ca(2+) pathways and partially regulated by N-ethyl-maleimide-sensitive factor-Ca(2+) pathways. LTA-PGN stimulation caused rapid and potent increase followed by gradual decrease of Ang-2. It was partially regulated by both Ral A-phospholipase D and NSF-Ca(2+) pathways.

CONCLUSIONS: We demonstrated characteristics and involved pathways for two distinctive secretory mechanisms, constitutive and stimulated, of Ang-2 in pulmonary microvascular endothelial cells. Considering the close correlation of Ang-2 with sepsis outcomes, our findings provide a better understanding of an important mechanism associated with sepsis pathophysiology and identify possible therapeutic targets to improve outcomes in the potentially lethal disease.

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author
publishing date
type
Contribution to journal
publication status
published
in
Lung
volume
42
issue
7
pages
12 pages
publisher
Springer
external identifiers
  • scopus:84984669456
ISSN
1432-1750
DOI
10.1080/01902148.2016.1218977
language
English
LU publication?
no
id
c4e5a46b-a5ef-42ab-b6e2-0ce20f9704ba
date added to LUP
2016-10-20 11:57:39
date last changed
2017-07-02 04:55:14
@article{c4e5a46b-a5ef-42ab-b6e2-0ce20f9704ba,
  abstract     = {<p>INTRODUCTION: Sepsis is characterized by dysregulated systemic inflammation and cytokine storm. Angiopoietin-2 (Ang-2) is known to closely correlate with severity of sepsis-related acute lung injury and mortality. The aim of this study was to clarify the mechanisms involved in Ang-2 secretion to better understand the pathophysiology of sepsis.</p><p>MATERIALS AND METHODS: The concentration of Ang-2 was assessed in culture medium of pulmonary microvascular endothelial cells in the presence or absence of Gram-positive bacteria cell wall components [lipoteichoic acid (LTA) and peptidoglycan (PGN)] stimulation at different time points ranging from 15 minutes to 24 hours. Constitutive and LTA-PGN-stimulated Ang-2 level changes were also assessed after cells were pretreated with different pathway inhibitors for 1 hour.</p><p>RESULTS: Two distinctive mechanisms of Ang-2 secretion, constitutive and stimulated secretion, were identified. Constitutive secretion resulted in slow but continuous increase in Ang-2 in culture medium over time. It was regulated by 3'5'-cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA)-Ca(2+) and nitric oxide (NO)-3'5'-cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG)-Ca(2+) pathways and partially regulated by N-ethyl-maleimide-sensitive factor-Ca(2+) pathways. LTA-PGN stimulation caused rapid and potent increase followed by gradual decrease of Ang-2. It was partially regulated by both Ral A-phospholipase D and NSF-Ca(2+) pathways.</p><p>CONCLUSIONS: We demonstrated characteristics and involved pathways for two distinctive secretory mechanisms, constitutive and stimulated, of Ang-2 in pulmonary microvascular endothelial cells. Considering the close correlation of Ang-2 with sepsis outcomes, our findings provide a better understanding of an important mechanism associated with sepsis pathophysiology and identify possible therapeutic targets to improve outcomes in the potentially lethal disease.</p>},
  author       = {Lee, Ji Young and Linge, Helena M and Ochani, Kanta and Lin, Ke and Miller, Edmund J},
  issn         = {1432-1750},
  language     = {eng},
  month        = {09},
  number       = {7},
  pages        = {335--345},
  publisher    = {Springer},
  series       = {Lung},
  title        = {Regulation of angiopoietin-2 secretion from human pulmonary microvascular endothelial cells},
  url          = {http://dx.doi.org/10.1080/01902148.2016.1218977},
  volume       = {42},
  year         = {2016},
}