US EPA

2264821 

Journal Article 

Abstract 

Enhanced arginase activity by TGF-β2 impacts nitric oxide production in lung epithelial cells by limiting L-arginine availability 

Jiang, J; George, SC 

2010 

Yes 

American Journal of Respiratory and Critical Care Medicine
ISSN: 1073-449X
EISSN: 1535-4970 

181 

A2699 

English 

10.1164/ajrccm-conference.2010.181.1_MeetingAbstracts.A2699 

WOS:000208771001612 

is part of a larger document 3452678 Proceedings of the American Thoracic Society 2010 International Conference, May 14-19, 2010, New Orleans

Introduction.
Recent study suggests that alterations in L-arginine metabolism play a role in asthma pathophysiology. Nitric oxide (NO) synthase and arginase, two enzymes that utilize L-arginine, are both upregulated in asthmatics. We previously demonstrated that TGF-β2 could upregulate arginase activity and impact gas phase NO release in lung epithelial cells. The aim of this study is to further investigate the impact of arginase activity on substrate availability for NOS and NO production in those cells.

Methods.
A549 cells, a model cell line of type II alveolar epithelium were cultured in DMEM/F-12 medium with various L-arginine concentrations (50μM, 100μM and 1mM) at an air-liquid interface in Transwell plates. The cells were then stimulated with cytomix (IL-1β, TNF-α, and IFN-γ, 10 ng/mL for each cytokine) or preincubation cells with 5ng/ml TGF-β2 for 24 hours +cytomix +TGF-β2 (5 ng/mL). Arginase activity inhibitor (nor-NOHA) was added to the culture medium in some condition. NO production in medium was measured by Griess assay.

Results.
Baseline total nitrite/nitrate content in medium with 50μM, 100μM and 1mM L-arginine is 2.38±0.47μM, 2.75±1.04μM and 2.76±0.21μM, respectively. Cytomix
stimulation increased nitrite/nitrate content to 6.38±3.01μM, 5.49±0.78μM and 9.15±1.46μM, respectively. Addition of TGF-β2 decreased total NO production by 93%, 82% and 62%, respectively. Arginase activity inhibitor partly reverses the reduction of total NO production in all three concentrations.

Conclusions:
Addition of TGF-β2 greatly reduces cytomix-induced NO production especially in lower L-arginine concentration condition, indicating that TGF-β2 enhanced arginase activity may regulate NO production by limiting the substrate availability for nitric oxide synthase. (NIH grants HL067954 and HL070645) 

American Thoracic Society 2010 International Conference 

New Orleans, LA 

May 14-19, 2010