| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Guest Access | Sign In via User Name/Password
|
|
|
|||||||
Guest Access | Sign In via User Name/Password |
|||||||||
1-Antitrypsin Activity Explain the Link Between Cigarette Smoking and Idiopathic Pulmonary Fibrosis?*
* From the Division of Pulmonary Sciences and Critical Care Medicine (Dr. Chan), Department of Medicine, National Jewish Medical and Research Center, and Division of Infectious Disease (Dr. Shapiro), University of Colorado Health Sciences Center, Denver, CO; and the Holland Laboratory (Dr. Ralston), Plasma Derivatives Department, American Red Cross, Rockville, MD.
Correspondence to: Edward D. Chan, MD, FCCP, K613e, Goodman Building, National Jewish Medical and Research Center, 1400 Jackson St, Denver, CO; e-mail: chane{at}njc.org
Key Words: 
1-antitrypsin • nitric oxide, pulmonary fibrosis • serine protease • smoking
Cigarette smoking is a
risk
factor for idiopathic pulmonary fibrosis (IPF),1
a
fibrotic lung disease characterized in the early stages by injury to
the interstitial walls, followed by an inflammatory alveolitis and
progressive fibrosis.2
Nitric oxide (NO) is a potent
proinflammatory mediator that may contribute to the exudative injury
that occurs in the early stages of IPF. Experimental evidence suggests
that NO production from macrophages may enhance cell injury and
inflammation associated with IPF,3
4
as well as the
analogous pulmonary fibrosis associated with exposure to asbestos and
bleomycin.5
6
1-Antitrypsin (AAT), the most
abundant endogenous serine protease inhibitor, possesses
anti-inflammatory properties. AAT is present in the serum at
concentrations of 1.5 to 3.5 mg/mL, but levels can increase up to four
times in inflammatory states.7
8
9
Nagai and
coworkers10
showed that intraperitoneal AAT administration
reduced bleomycin-induced pulmonary fibrosis in hamsters. This
protective AAT effect was not due to alteration in elastase activity,
chemotaxis, or neutrophil superoxide generation. The mechanism of AAT
protection against pulmonary fibrosis is unexplained. Because NO and
AAT may play opposing roles in lung inflammation and fibrosis, we
investigated the effects of AAT on NO expression induced by interferon
(IFN)-
plus lipopolysaccharide (LPS) in mouse macrophages.
Experimental Procedures
AAT was purified from Cohn fraction IV-1 from the plasma of
healthy volunteers. Successive anion-exchange and
cation-exchange chromatography produced fully active AAT, as assessed
by porcine elastase inhibition assay and array nephelometric antigen
analysis. AAT recovered was > 94% pure by sodium
dodecylsulfate-polyacrylamide gel electrophoresis and high-performance
liquid chromatography assessment. Nitrite
(NO2-) concentration was measured using the
Greiss reagent assay, and mitogen-activated protein kinase (MAPK)
activity was quantified as previously described.11
Western
blot analysis of inducible NO synthase (iNOS) protein synthesis and
electrophoretic mobility shift assays to assess nuclear factor-
B
activity were also performed.
Results
RAW 264.7 macrophages were pretreated with physiologic
concentrations of AAT for 1 h and then costimulated with LPS (1
ng/mL) plus IFN- (10 U/mL) for 18 h.
NO2-, the metabolite of NO, was quantified in
the supernatant and immunoblots of whole cell lysates were performed to
determine iNOS expression. As shown in Figure 1
, top,
A,
AAT at 0.1 mg/mL inhibited NO2- production by
approximately 40% and by nearly 100% at a physiologic concentration
of 3 mg/mL compared to cells cultured with stimuli alone. AAT at 3
mg/mL also substantially inhibited iNOS expression, as shown in Figure 1 , bottom, B. The diluent in which AAT was reconstituted did
not affect NO production or iNOS expression (Fig 1
, top, A,
and bottom, B). MAPKs have been implicated in iNOS induction
following stimulation with tumor necrosis factor-, interleukin-1,
interleukin-1ß, or LPS. Therefore, we investigated the effects of AAT
on IFN- plus LPS activation of extracellular-signal regulated
kinase, p38 MAPK, and c-Jun-NH2-terminal kinase.
AAT affected neither phosphorylation nor activation of p38 MAPK
and c-Jun-NH2-terminal kinase (data not shown). However,
AAT modestly inhibited extracellular-signal regulated kinase
phosphorylation (data not shown). In separate studies, AAT inhibited
LPS-induced activation of nuclear factor-B in RAW 264.7 cells as
determined by electrophoretic mobility shift assays (data not shown).
|
We demonstrated that AAT is a potent suppressor of NO production and iNOS expression at physiologic concentrations. Thus, cigarette smoking may predispose to pulmonary fibrosis by two separate mechanisms. First, cigarette smoke, known to contain high concentrations of reactive oxygen and nitrogen species, may initiate inflammation and NO production that leads to pulmonary fibrosis. Second, since cigarette smoke inactivates AAT in vivo,12 smoking reduces the function of an important endogenous inhibitor of NO production. Therefore, reduced AAT activity as a result of cigarette smoking may increase NO production and predispose susceptible individuals to lung injury and subsequent pulmonary fibrosis.
Footnotes
Abbreviations: AAT = 1-antitrypsin;
IFN = interferon; iNOS = inducible nitric oxide synthase;
IPF = idiopathic pulmonary fibrosis; LPS = lipopolysaccharide;
MAPK = mitogen-activated protein kinase; NO = nitric oxide;
NO2- = nitrite
References
1-Antitrypsin: molecular pathology, leukocytes, and tissue damage. J Clin Invest 78,1427-1431
1-antitrypsin deficiency. Ann Allergy 72,105-121[ISI][Medline]
1-Antitrypsin: molecular structure and the Pi system. Acta Paediatr Suppl 393,1-4
1-proteinase inhibitor ameliorates bleomycin-induced pulmonary fibrosis in hamsters. Am Rev Respir Dis 145,651-656[ISI][Medline]
and TNF in mouse macrophages. J Immunol 162,415-4221-antitrypsin for neutrophil elastase. J Clin Invest 87,1060-1065This article has been cited by other articles:
|
|
 |
|
  J.-H. Chen, T.-H. Tseng, Y.-C. Ho, H.-H. Lin, W.-L. Lin, and C.-J. Wang Gaseous Nitrogen Oxides Stimulate Cell Cycle Progression by Rubidium Phosphorylation via Activation of Cyclins/Cdks Toxicol. Sci., November 1, 2003; 76(1): 83 - 90. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
