Mechanism of bronchoprotective effects of a novel natriuretic hormone peptide.
BACKGROUND
The natriuretic hormone peptide (NHP)(99-126), a C-terminal peptide of pro-atrial natriuretic factor (proANF), induces bronchodilatory effects in people with asthma. Recently, another plasmid-encoded C-terminal peptide, pNHP(73-102), was shown to induce a long-lasting bronchoprotective effect in a mouse model of allergic asthma.


OBJECTIVE
This study was carried out to determine the role of lung epithelial cells in the bronchoprotective and anti-inflammatory activity of these peptides.


METHODS
Human type II alveolar epithelial cells (A549) and normal human bronchial epithelial (NHBE) cells were transfected with pNHP(73-102) to test the effect of this peptide on activation of these cells. After transfection, cells were analyzed for changes in Ca(++) and nitric oxide (NO) levels. Also, activation of NFkappaB and the extracellularly regulated kinase (ERK) 1, 2 signaling pathway was examined by luciferase reporter assay and phosphorylation studies respectively.


RESULTS
Analysis of intracellular Ca(++) levels in pNHP(73-102) -transfected A549 or NHBE showed that the peptide increases release. This Ca(++) release was accompanied by an increase in the production of NO. Also, overexpression of pNHP(73-102), but not pVAX control, in phorbol myristate acetate-activated A549 cells resulted in a significant decrease in expression of a cotransfected nuclear factorkappaB (NFkappaB)-luciferase reporter. Similarly, pNHP(73-102) decreased TNF-alpha-induced NFkappaB activation in NHBE cells. Furthermore, NHP(73-102) but not atrial natriuretic peptide decreased phosphorylation of Erk-1, 2 in A549 cells.


CONCLUSIONS
Overexpression of pNHP(73-102) in epithelial cells causes increased production of intracellular Ca(++) and NO, with a concomitant decrease in activation of NFkappaB and ERK1, 2. These results suggest a bronchodilatory and anti-inflammatory activity of this peptide.
Hellermann
Gary
G
Department of Internal Medicine, University of South Florida College of Medicine, Tampa, FL 33612, USA.
Kong
Xiaoyuan
X
Gunnarsdóttir
Jóhanna
J
San Juan
Homero
H
Singam
Raji
R
Behera
Sumita
S
Zhang
Weidong
W
Lockey
Richard F
RF
Mohapatra
Shyam S
SS
D009320:Atrial Natriuretic Factor / Q000235:genetics / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D011650:Pulmonary Alveoli / Q000166:cytology*; D014162:Transfection
D016328:NF-kappa B; D009569:Nitric Oxide; D009320:Atrial Natriuretic Factor; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium