Department of Toxicology and Pharmacology, Rutgers University and Environmental and Community Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854-8020
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Lung injury induced by acute
endotoxemia is associated with increased generation of inflammatory
mediators such as nitric oxide and eicosanoids, which have been
implicated in the pathophysiological process. Although production of
these mediators by alveolar macrophages (AM) has been characterized,
the response of type II cells is unknown and was assessed in the
present studies. Acute endotoxemia caused a rapid (within 1 h) and
prolonged (up to 48 h) induction of nitric oxide synthase-2
(NOS-2) in type II cells but a delayed response in AM (12-24 h).
In both cell types, this was associated with increased nitric oxide
production. Although type II cells, and to a lesser extent AM,
constitutively expressed cyclooxygenase-2, acute endotoxemia did not
alter this activity. Endotoxin administration had no effect on
mitogen-activated protein kinase or protein kinase B- (PKB-
)
expression. However, increases in phosphoinositide 3-kinase and
phospho-PKB-
were observed in type II cells. The finding that this
was delayed for 12-24 h suggests that these proteins do not play a
significant role in the regulation of NOS-2 in this model. After
endotoxin administration to rats, a rapid (within 1-2 h)
activation of nuclear factor-
B was observed. This response was
transient in type II cells but was sustained in AM. Interferon
regulatory factor-1 (IRF-1) was also activated rapidly in type II
cells. In contrast, IRF-1 activation was delayed in AM. These
data demonstrate that type II cells, like AM, are highly responsive
during acute endotoxemia and may contribute to pulmonary inflammation.
type II cells; alveolar macrophages; nitric oxide synthase-2; cycloxygenase-2; nuclear factor-B; interferon regulatory factor-1
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
EXPOSURE OF HUMANS AND
ANIMALS to excessive amounts of bacterially derived endotoxin is
known to elicit an inflammatory reaction and can cause severe damage to
various organs, including the lung and liver (14).
Alveolar macrophages are known to play a central role in initiating and
regulating endotoxin-induced inflammatory responses in the lung. This
is accomplished through the release of a variety of mediators,
including cytokines, reactive oxygen intermediates, reactive nitrogen
intermediates, and eicosanoids by these cells (28, 49).
Type II alveolar epithelial cells are important in maintaining the
functional and structural integrity of the alveolus. These cells not
only synthesize and secrete surfactant but also act as progenitors for
injured type I epithelial cells (1, 19). A number of
studies have suggested that type II cells also have the capacity to
participate in inflammatory processes. Thus, in response to cytokines,
type II cells, like alveolar macrophages, release tumor necrosis
factor-, interleukin-8, monocyte chemotactic protein, macrophage
inflammatory protein-2, nitric oxide, hydrogen peroxide, and
prostaglandins (13, 23, 31, 32, 39, 40, 43, 56, 57). The
functional and biochemical responses of type II cells during acute
endotoxemia are largely unknown, and an analysis of their activity when
compared with alveolar macrophages represents the focus of the present
studies. We found that administration of endotoxin to rats resulted in
induction of nitric oxide synthase-2 (NOS-2) protein and increased
nitric oxide production in both cell types. Nuclear factor-
B
(NF-
B) and interferon regulatory factor-1 (IRF-1), two key
transcription factors known to activate genes that generate
inflammatory mediators, were also induced in type II cells and alveolar
macrophages by endotoxin; however, the kinetics of their responses were
different. The results of our studies provide support for the concept
that type II cells, like alveolar macrophages, participate in pulmonary
inflammatory responses to irritants although their actions may be distinct.
![]() |
MATERIALS AND METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Animals and treatment. Female specific pathogen-free Sprague-Dawley rats (200-225 g, 6-8 wk) were purchased from Taconic (Germantown, NY). Animals were housed in microisolator cages and maintained on sterile food and pyrogen-free water ad libitum. Acute endotoxemia was induced by intravenous injection of rats with 5 mg/kg Escherichia coli lipopolysaccharide (LPS, serotype 0128:B12; Sigma Chemical, St. Louis, MO).
Cell isolation. Rats were killed by intraperitoneal injection of Nembutal (125 mg/kg). The lungs were perfused with 50 ml of warm (37°C) Ca2+/Mg2+-free Hanks' balanced salt solution (HBSS) (pH 7.4) containing 2.5 M HEPES, 0.5 M EGTA, and 4.4 M NaHCO3 at a rate of 22 ml/min followed by perfusion with 50 ml HBSS without EGTA. Lungs were then lavaged five to six times with HBSS to collect alveolar macrophages. Cells were washed three to four times with HBSS containing 2% FCS. Cell viability was 98%, as determined by trypan blue dye exclusion, and cell purity was >97%, as determined morphologically after Giemsa staining.
Type II cells were isolated from lavaged lungs as previously described (17, 40). After being washed two times with 10 ml of buffer (in mM: 140 NaCl, 5 KCl, 2.5 Na2HPO4, 10 HEPES, 1.3 MgSO4 · 7H2O, pH 7.4, and 2 CaCl2), 30 ml of elastase (4.2 U/ml; Worthington Biochemicals) were infused in the lungs using a 60-ml syringe. The tissue was then incubated at 37°C for 20 min, the trachea and major bronchi were removed, and the lungs were minced in the presence of 4 ml DNase (1 µg/ml) and then digested for 5 min at 37°C with 10 ml of elastase. The reaction was stopped by the addition of 5 ml FCS. The tissue was then sequentially filtered through 220, 60, 30, and 15 µm nylon mesh. Cells were collected, washed, and purified by negative selection (1 h, 37°C) on IgG-coated plates. Nonadherent cells were collected and washed with DMEM containing 10% FCS. Cell purity, assessed by modified Papinicolou staining, was 95%, and viability, determined by trypan blue dye exclusion, was >98%.Measurement of nitric oxide production.
Alveolar macrophages (2 × 105 cells/well) and type II
cells (3 × 105 cells/well) were inoculated in 96-well
dishes in phenol red-free DMEM containing 10% FCS and inteferon-
(IFN-
; 10 U/ml), LPS (10 ng/ml), IFN-
plus LPS, or medium control
with and without 0.5-5 µM pyrrolidine dithiocarbamate (PDTC).
Nitric oxide was quantified 24 h later by nitrite accumulation in
the culture medium using a procedure based on the Greiss reaction with
sodium nitrite as the standard (22). For nitrate
determinations, samples were treated with nitrate reductase and NADPH
for 2 h before analysis using a nitrate/nitrite colorimetric assay
kit (Cayman Chemical, Ann Arbor, MI). We found that, in medium from
cells treated for 24 h with LPS and IFN-
, the ratio of nitrate
to nitrite was 2:1 for alveolar macrophages and 2.5:1 for type II
cells, and this ratio did not change after endotoxin administration.
Preparation of cytoplasmic and nuclear extracts.
Cytoplasmic extracts for Western blotting and nuclear extracts for the
electrophoretic mobility shift assays (EMSA) were prepared as
previously described (10). Briefly, either freshly
isolated cells or cells cultured in six-well plates (2 × 106 cells/well) for 24 h in the presence or absence of
LPS (10 ng/ml) plus IFN- (10 U/ml) with and without PDTC (1.0 or 2.5 µM) were lysed in buffer (in mM: 10 HEPES, pH 7.4, 10 KCl, 2 MgCl2, and 2 EDTA) on ice for 10 min with intermittent
mixing. Nonidet P-40 was added to give a final concentration of 10%.
After 5 min on ice, the cells were centrifuged (4°C, 16,000 g, 5 min), and supernatants containing cytoplasmic extracts
were collected. To prepare nuclear extracts, pellets were resuspended
in extraction buffer (50 mM HEPES, pH 7.4, 50 mM KCl, 300 mM NaCl, 0.1 mM EDTA, and 10% glycerol) and incubated on ice for 20 min with
periodic mixing. The cells were then centrifuged (4°C, 16,000 g, 5 min), and supernatants containing nuclear extracts were
collected. Aliquots of cytoplasmic and nuclear extracts were frozen at
70°C until analysis. Protein determinations were performed using
the BCA Protein Assay kit (Pierce, Rockford, IL) with BSA as the standard.
Western blot analysis.
Cytoplasmic proteins were fractionated on SDS-PAGE (7.5-15%). The
proteins were then transferred to nitrocellulose paper. Nonspecific
binding was blocked by incubation of the blot for 30 min at room
temperature with 5% nonfat dry milk in enhanced chemiluminescence
(ECL) buffer (Amersham Life Sciences, Arlington Heights, IL). This was
followed by incubation for 16-24 h at 4°C with primary antibody
(Transduction Laboratories, San Diego, CA, or New England Biolabs,
Beverly, MA). After extensive washing with ECL buffer, the blot was
incubated with a 1:4,000 dilution of horseradish peroxidase-conjugated
secondary antibody at room temperature for 1 h. Proteins were
detected using an ECL detection system. The dilutions of primary
antibodies and amounts of protein analyzed per lane were as follows:
p38 mitogen-activated protein kinase (MAPK) and p44/42 MAPK, 1:500, 5 µg; phospho-protein kinase B (PKB)-, 1:500, 8 µg;
cyclooxygenase-2 (Cox-2) and phosphoinositide 3-kinase (PI 3-kinase,
p85 subunit), 1:250, 10 µg; PKB-
, 1:200, 20 µg; phospho-p38
MAPK, 1:100, 10 µg; NOS-2, 1:100, 20 µg; and phospho-p44/42 MAPK,
1:50, 20 µg.
EMSA.
EMSA were performed as described previously (10) with some
modifications. Binding reactions were carried out at room temperature for 30 min in a total volume of 15 µl containing 2-5 µg of
nuclear extracts, 5 µl of 5× gel shift binding buffer (20%
glycerol, 5 mM MgCl2, 2.5 mM EDTA, 2.5 mM dithiothreitol,
250 mM NaCl, and 50 mM Tris · HCl, pH 7.5), 2 µg poly(dI-dC)
and 3 × 104
counts · min1 · µl
1
[
-32P]ATP (3,000 Ci/mmol at 10 mCi/ml)-labeled NF-
B
(5'-AGT TGA GGG GAC TTT CCC AGG C-3'; Promega Gel Shift Assay Systems,
Madison, WI), or IRF-1 (5'-GGA AGC GAA AAT GAA ATT GAC T-3'; Santa Cruz Biotechnology, Santa Cruz, CA) consensus oligonucleotides. Protein-DNA complexes were separated on 5 or 7% nondenaturing polyacrylamide gels
run at 250 V in 0.5× TBE (45 mM Tris-borate and 1 mM EDTA, pH 8.0),
visualized after the gels were dried, and autoradiographed. For
supershift reactions, 1 µg of antibodies to NF-
B subunits (p50 and
p65) or IRF-1 (Santa Cruz Biotechnology) was added to the reaction
mixtures and incubated on ice for 15 min before the addition of labeled
oligonucleotide. For competitor reactions, 40-fold excess of the
respective unlabeled oligonucleotide was added to the mixture before
the addition of the labeled probe.
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Effects of acute endotoxemia on NOS-2 expression and nitric oxide
production.
In initial studies, we analyzed the effects of endotoxin treatment of
rats on expression of NOS-2, the enzyme mediating the generation of
nitric oxide in type II cells and alveolar macrophages (31, 33,
38, 40). NOS-2 protein was not detectable in freshly isolated
type II cells or alveolar macrophages from control animals (Fig.
1). Endotoxin administration resulted in
a time-dependent induction of NOS-2 in both cell types. However, the
kinetics of their responses were distinct. Thus, although in type II
cells NOS-2 protein was expressed as early as 1 h after endotoxin
administration and persisted for at least 48 h, in alveolar
macrophages this response was delayed. Moreover, in these cells NOS-2
protein declined to control levels after 24 h (Fig. 1).
|
|
|
Effects of acute endotoxemia on Cox-2 expression. In our next series of studies, we determined if type II cells and alveolar macrophages were activated after endotoxin administration to express increased amounts of Cox-2, the enzyme mediating inducible prostaglandin biosynthesis (36, 47). Freshly isolated type II cells from control animals were found to constitutively express Cox-2 protein (Fig. 1). Two protein bands were detected in the blots, with the lower band most likely reflecting a Cox-2 breakdown product. Although similar results were observed in alveolar macrophages, significantly greater quantities of Cox-2 protein were identified in type II cells. In contrast to its effects on NOS-2, induction of acute endotoxemia had no major effects on Cox-2 expression in either cell type (Fig. 1).
Biochemical activation of type II cells and alveolar macrophages
during acute endotoxemia.
In further studies, we determined if acute endotoxemia was associated
with biochemical activation of the cells. Initially, we analyzed
expression of p38 and p44/42 MAPK, which are thought to be involved in
the regulation of both NOS-2 and Cox-2 (8, 11, 20).
Freshly isolated type II cells from control animals were found to
constitutively express both total and phosphorylated p38 and p44/42
MAPK (Fig. 4). Endotoxin administration
had no major effect on expression of these proteins. Similarly, freshly isolated alveolar macrophages from control animals were found to
constitutively express total p38 and p44/42 MAPK, as well as phospho-p38 MAPK but not phospho-p44/42 MAPK. Moreover, endotoxin administration had no effect on expression of MAPK proteins in alveolar
macrophages (Fig. 4).
|
Effects of acute endotoxemia on NF-B and IRF-1 nuclear binding
activity.
The transcription factors NF-
B and IRF-1 are known to regulate the
expression of numerous inflammatory genes, including NOS-2 and Cox-2
(6, 9, 20). We next determined if acute endotoxemia was
associated with altered nuclear binding activity of these transcription
factors. NF-
B nuclear binding activity was not detectable in freshly
isolated type II cells from control rats (Fig.
5, left). Treatment of the
animals with endotoxin resulted in a rapid (within 1 h) and
transient increase in NF-
B binding activity. Two NF-
B complexes
(I and II) were detected in the cells. Antibodies to p50 and p65 were
found to alter the migration of these complexes (Fig. 5,
middle). Binding was eliminated by an excess of unlabeled
NF-
B, demonstrating the specificity of the probe. As observed with
NF-
B, IRF-1 binding activity was not detected in freshly isolated
type II cells from control animals (Fig.
6, left). Treatment of animals
with endotoxin resulted in a rapid (within 2 h) and prolonged
induction of IRF-1 nuclear binding activity in these cells. Binding was
decreased in the presence of anti-IRF-1 antibody and excess unlabeled
IRF-1 (Fig. 6, middle).
|
|
Effects of inhibiting NF-B on NOS-2 expression and nitric oxide
production.
To analyze the potential role of NF-
B in NOS-2 expression and nitric
oxide production, we used PDTC, which has been reported to block
NF-
B nuclear binding activity (7, 51). PDTC was found
to cause a dose-related inhibition of NOS-2 protein expression in the
cells, with maximum effects at 2.5 µM (Fig. 3). Type II cells and
alveolar macrophages from endotoxin-treated rats were less sensitive to
the inhibitory effects of PDTC on NOS-2 protein expression than were
cells from control animals. We also found that PDTC treatment caused a
dose-dependent inhibition of nitric oxide production by both type II
cells and alveolar macrophages, reaching a maximum with 2.5 µM (Fig.
7). At this concentration, PDTC had no
effect on cell viability (data not shown). Alveolar macrophages from
endotoxin-treated rats were less sensitive to the inhibitory effects of
PDTC on nitric oxide production than were cells from control animals.
To exclude the possibility that PDTC was acting as a nitrite scavenger
(44), we quantified nitrite levels in a standard solution
containing increasing concentrations of sodium nitrite (5-35 µM)
in the presence and absence of 5 µM PDTC. We found that PDTC had no
effect on nitrite levels in the solution (data not shown). Moreover,
EMSA showed that PDTC was effective in blocking NF-
B nuclear binding
activity in type II cells and alveolar macrophages (data not shown).
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The role of type II cells in inflammatory responses of the lung has received relatively limited attention. The fact that these cells release cytokines and reactive oxidants suggests that their participation in these responses may be significant. In this regard, recent studies have demonstrated that type II cells are activated to produce increased quantities of nitric oxide, hydrogen peroxide, and superoxide anion after exposure of animals to pulmonary irritants such as ozone or particulate matter (29, 40, 46). The present studies demonstrate that a number of functional and biochemical activities are upregulated or induced in type II cells after endotoxin administration to rats. In fact, these cells appear to be more responsive to endotoxin than alveolar macrophages. These findings are similar to our studies on interstitial macrophages (53, 54) and suggest that close association with the endothelium increases the sensitivity of cells to intravenously administered endotoxin.
Nitric oxide is a highly reactive molecule produced in type II cells
and alveolar macrophages by the NADPH-dependent enzyme NOS-2 (31,
33, 38, 40). We found that acute endotoxemia caused a rapid- and
time-dependent induction of NOS-2 in type II cells, suggesting that
these cells are highly responsive to in vivo endotoxin. This is
supported by our findings that type II cells from endotoxemic animals
are sensitized to produce more nitric oxide and express greater amounts
of NOS-2 after treatment with IFN- plus LPS, compared with cells
from control animals. Our data are consistent with previous findings of
increased NOS-2 in type II cells after ozone inhalation
(40) and support the idea that these cells are an
important part of the inflammatory response to pulmonary irritants. The
relatively delayed production of nitric oxide in vitro by type II cells
after endotoxin administration, compared with alveolar macrophages,
suggests that they may need to be activated or primed for mediator
production. As described previously (53), alveolar
macrophages were also found to produce more nitric oxide in response to
inflammatory mediators after endotoxin administration to rats. However,
the response of these cells was more rapid compared with type II cells
(12 vs. 24 h). This is consistent with a primary role of alveolar
macrophages in the pulmonary inflammatory response (21, 26,
58).
Prostaglandins are highly reactive lipid mediators released during inflammatory responses from arachidonic acid via the enzyme Cox-2 (36, 47). We found that Cox-2 was constitutively expressed in type II cells and alveolar macrophages from control rats. This is in accord with previous studies examining rat and mouse lung macrophages (18, 50). These findings suggest that Cox-2 may be important in maintaining homeostatic pulmonary activity. In this regard, Cox-2-dependent pathways have been implicated in the regulation of lung vascular tone, alveolar epithelial permeability, surfactant homeostasis, and lung development (4, 16, 25, 30, 41, 48). Endotoxin administration to the animals had no significant effect on expression of Cox-2 in type II cells or alveolar macrophages. This indicates that Cox-2 expression in these cells does not limit prostaglandin production in the lung during endotoxin-induced inflammation.
MAPK signaling pathways are known to play a central role in the regulation of a number of inflammatory responses, including NOS-2 and Cox-2 expression (8, 11, 20). Our studies revealed that both p38 and p44/42 MAPK were constitutively expressed in type II cells from control animals, which may explain constitutive expression of Cox-2 in these cells. Endotoxin administration had no effect on expression of either total MAPK or phospho-MAPK. These findings are consistent with the lack of effects of endotoxin on Cox-2. It should be noted, however, that it is not known if the MAPK are functionally active in type II cells. Additional studies are required to determine the precise role of MAPK in these cells. Constitutive p38 MAPK and phospho-p38 MAPK were also detected in alveolar macrophages, and, as observed in type II cells, these proteins were unaffected by endotoxin administration. These results, together with the observation that alveolar macrophages did not express phospho-p44/42 MAPK in response to endotoxin, suggest that activation of these proteins may not be required for NOS-2 expression in these lung cells. This idea is supported by recent studies in mouse macrophage and epithelial cell lines demonstrating that activation of p44/42 MAPK is not essential for LPS-induced NOS-2 expression (27).
Constitutive expression of PI 3-kinase, PKB-, and
phospho-PKB-
was also observed in type II cells from control
animals. It has been suggested that PI 3-kinase is involved in the
regulation of MAPK and Cox-2 (34). Our findings that
expression of PI 3-kinase and phospho-PKB-
increased after endotoxin
administration to the animals provides additional support for the
concept that type II cells are activated during acute endotoxemia. The
observation that PI 3-kinase and phospho-PKB-
expression is induced
in type II cells during acute endotoxemia is novel. At the present
time, the functions of these proteins in type II cell activation are unknown. Although they may be involved in constitutive Cox-2
expression, PI 3-kinase and PKB-
may also contribute to type II cell
survival, proliferation, protein synthesis, and/or glucose transport,
and this remains to be determined (3, 37, 45). Alveolar
macrophages from control animals also constitutively expressed PI
3-kinase and PKB-
, but not phospho-PKB-
. Although endotoxin
treatment of the animals induced PI 3-kinase, it had no effect on
either PKB-
or phospho-PKB-
expression. This suggests distinct
functions for PKB-
in type II cells and alveolar macrophages during
endotoxin-induced lung injury.
The promoter regions of both the NOS-2 and Cox-2 genes contain
consensus sequences for the transcription factors NF-B and IRF-1,
which presumably regulate the activity of these genes (6, 9,
20). We found that the time course of induction of NOS-2 in type
II cells after endotoxin administration correlated with activation of
NF-
B and IRF-1 nuclear binding activity. Of interest is our finding
that NF-
B activation in type II cells after endotoxin administration
was transient, whereas IRF-1 activity was prolonged. This suggests that
the combined actions of these transcription factors may be required for
prolonged expression of NOS-2 in type II cells during acute
endotoxemia. In this regard, recent studies have demonstrated that
multiple transcription factors are involved in regulating NOS-2 gene
activity (35). The fact that constitutive NF-
B and
IRF-1 were not evident in type II cells indicates that other pathways
control Cox-2 and MAPK expression. Our observation that NF-
B
activity is increased after endotoxin administration is in accord with
previous studies demonstrating activation of this transcription factor
in type II cells and alveolar macrophages after exposure of animals to
ozone, particulate matter, or asbestos (29, 42) and
suggests that upregulation of transcription factors may be a general
response to pulmonary injury (12).
Alveolar macrophages from control animals exhibited low levels of
constitutive NF-B binding activity. Endotoxin administration caused
a rapid and prolonged activation of NF-
B in these cells, which is
also consistent with increased NOS-2 expression and nitric oxide
production. Our findings that blocking NF-
B with PDTC inhibited nitric oxide production and NOS-2 expression in both type II cells and
alveolar macrophages provide additional support for an involvement of
this transcription factor in the regulation of NOS-2 in these cells.
Our results are consistent with previous reports showing activation of
NF-
B in alveolar macrophages after endotoxin treatment of animals
and during sepsis (2, 5). The observation that IRF-1
activation was delayed in alveolar macrophages after endotoxin administration suggests that this transcription factor does not play a
major role in induction of NOS-2 in these cells. In alveolar macrophages, constitutive IRF-1 activity was correlated with expression of MAPK, PKB-
, and PI 3-kinase. One can speculate that this
transcription factor may regulate signaling pathways mediated by these
proteins under homeostatic conditions (6, 20).
The present studies demonstrate that endotoxin administration to rats activates type II cells and alveolar macrophages for increased nitric oxide production. However, distinct signaling molecules appear to be involved in the regulation of NOS-2 in these two cell types during acute endotoxemia, and this may be attributed to differences in their origin and function. Thus, although type II cells are epithelial in origin, alveolar macrophages are derived from myeloid precursors. Type II cells also have a more limited life span compared with alveolar macrophages, which are relatively long-lived cells and can persist within inflammatory lesions. Further studies are needed to determine the precise signaling pathways activated in each cell type during acute endotoxemia and their relative contributions to pulmonary inflammation.
![]() |
ACKNOWLEDGEMENTS |
---|
This work was supported by National Institute of Environmental Health Sciences Grants ES-04738, ES-06897, and ES-05022 and by a Career Development Award from the Burroughs Wellcome Fund.
![]() |
FOOTNOTES |
---|
Address for reprint requests and other correspondence: D. Laskin, Rutgers Univ., Dept. of Pharmacology and Toxicology, 170 Frelinghuysen Road, Piscataway, NJ 08854-8020 (E-mail: laskin{at}eohsi.rutgers.edu).
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
10.1152/ajplung.00217.2001
Received 13 June 2001; accepted in final form 28 November 2001.
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
1.
Adamson, IY,
and
Bowden DH.
The type 2 cell as progenitor of alveolar epithelial regeneration. A cytodynamic study in mice after exposure to oxygen.
Lab Invest
30:
35-42,
1974[ISI][Medline].
2.
Amory-Rivier, CF,
Mohler J,
Bedos JP,
Azoulay-Dupuis E,
Henin D,
Muffat-Joly M,
Carbon C,
and
Moine P.
Nuclear factor-kappaB activation in mouse lung lavage cells in response to Streptococcus pneumoniae pulmonary infection.
Crit Care Med
28:
3249-3256,
2000[ISI][Medline].
3.
Ardeshna, KM,
Pizzey AR,
Devereux S,
and
Khwaja A.
The PI3 kinase, p38 SAP kinase, and NF-kappaB signal transduction pathways are involved in the survival and maturation of lipopolysaccharide-stimulated human monocyte-derived dendritic cells.
Blood
96:
1039-1046,
2000
4.
Arias-Diaz, J,
Vara E,
Garcia C,
and
Balibrea JL.
Tumor necrosis factor-alpha-induced inhibition of phosphatidylcholine synthesis by human type II pneumocytes is partially mediated by prostaglandins.
J Clin Invest
94:
244-250,
1994[ISI][Medline].
5.
Blackwell, TS,
Lancaster LH,
Blackwell TR,
Venkatakrishnan A,
and
Christman JW.
Differential NF-B activation after intratracheal endotoxin.
Am J Physiol Lung Cell Mol Physiol
277:
L823-L830,
1999
6.
Blanco, JC,
Contursi C,
Salkowski CA,
DeWitt DL,
Ozato K,
and
Vogel SN.
Interferon regulatory factor (IRF)-1 and IRF-2 regulate interferon gamma-dependent cyclooxygenase 2 expression.
J Exp Med
191:
2131-2144,
2000
7.
Brennan, P,
and
O'Neill LA.
2-Mercaptoethanol restores the ability of nuclear factor kappa B (NF kappa B) to bind DNA in nuclear extracts from interleukin 1-treated cells incubated with pyrollidine dithiocarbamate (PDTC). Evidence for oxidation of glutathione in the mechanism of inhibition of NF kappaB by PDTC.
Biochem J
320:
975-981,
1996[ISI][Medline].
8.
Caivano, M,
and
Cohen P.
Role of mitogen-activated protein kinase cascades in mediating lipopolysaccharide-stimulated induction of cyclooxygenase-2 and IL-1 beta in RAW264 macrophages.
J Immunol
164:
3018-3025,
2000
9.
Callejas, NA,
Casado M,
Bosca L,
and
Martin-Sanz P.
Requirement of nuclear factor kappaB for the constitutive expression of nitric oxide synthase-2 and cyclooxygenase-2 in rat trophoblasts.
J Cell Sci
18:
3147-3155,
1999.
10.
Carter, AB,
Monick MM,
and
Hunninghake GW.
Lipopolysaccharide-induced NF-kappaB activation and cytokine release in human alveolar macrophages is PKC-independent and TK- and PC-PLC-dependent.
Am J Respir Cell Mol Biol
18:
384-391,
1998
11.
Chen, C,
Chen YH,
and
Lin WW.
Involvement of p38 mitogen-activated protein kinase in lipopolysaccharide-induced iNOS and COX-2 expression in J774 macrophages.
Immunology
97:
124-129,
1999[ISI][Medline].
12.
Christman, JW,
Sadikot RT,
and
Blackwell TS.
The role of nuclear factor-kappa B in pulmonary diseases.
Chest
117:
1482-1487,
2000
13.
Cott, GR,
Westcott JY,
and
Voelkel NF.
Prostaglandin and leukotriene production by alveolar type II cells in vitro.
Am J Physiol Lung Cell Mol Physiol
258:
L179-L187,
1990
14.
Deitch, EA.
Multiple organ failure. Pathophysiology and potential future therapy.
Ann Surg
216:
117-134,
1992[ISI][Medline].
15.
Dekker, LV,
and
Segal AM.
Perspectives: signal transduction signals to move cells.
Science
287:
982-985,
2000
16.
Devalia, JL,
Sapsford RJ,
Cundell DR,
Rusznak C,
Campbell AM,
and
Davies RJ.
Human bronchial epithelial cell dysfunction following in vitro exposure to nitrogen dioxide.
Eur Respir J
6:
1308-1316,
1993[Abstract].
17.
Dobbs, LG,
Gonzalez R,
and
Williams MC.
An improved method for isolating type II cells in high yield and purity.
Am Rev Respir Dis
134:
141-145,
1986[ISI][Medline].
18.
Ermert, L,
Ermert M,
Goppelt-Struebe M,
Walmrath D,
Grimminger F,
Steudel W,
Ghofrani HA,
Homberger C,
Duncker H,
and
Seeger W.
Cyclooxygenase isoenzyme localization and mRNA expression in rat lungs.
Am J Respir Cell Mol Biol
18:
479-488,
1998
19.
Evans, MJ,
Cabral LJ,
Stephens RJ,
and
Freeman G.
Transformation of alveolar type 2 cells to type 1 cells following exposure to NO2.
Exp Mol Pathol
22:
142-150,
1975[ISI][Medline].
20.
Faure, V,
Hecquet C,
Courtois Y,
and
Goureau O.
Role of interferon regulatory factor-1 and mitogen-activated protein kinase pathways in the induction of nitric oxide synthase-2 in retinal pigmented epithelial cells.
J Biol Chem
274:
4794-4800,
1999
21.
Gauldie, J,
Jordana M,
and
Cox G.
Cytokines and pulmonary fibrosis.
Thorax
48:
931-935,
1993[Abstract].
22.
Green, LC,
Wagner DA,
Glogowski J,
Skipper PL,
Wishnok JS,
and
Tannenbaum SR.
Analysis of nitrate, nitrite, and [15N] nitrate in biological fluids.
Anal Biochem
126:
131-138,
1982[ISI][Medline].
23.
Grimminger, F,
von Kurten I,
Walmrath D,
and
Seeger W.
Type II alveolar epithelial eicosanoid metabolism: predominance of cyclooxygenase pathways and transcellular lipoxygenase metabolism in co-culture with neutrophils.
Am J Respir Cell Mol Biol
6:
9-16,
1992[ISI][Medline].
24.
Hirsch, E,
Katanaev VL,
Garlanda C,
Azzolino O,
Pirola L,
Silengo L,
Sozzani S,
Mantovani A,
Altruda F,
and
Wymann MP.
Central role for G protein-coupled phosphoinositide 3-kinase gamma in inflammation.
Science
287:
1049-1053,
2000
25.
Holtzman, MJ.
Arachidonic acid metabolism. Implications of biological chemistry for lung function and disease.
Am Rev Respir Dis
143:
188-203,
1991[ISI][Medline].
26.
Kooguchi, K,
Hashimoto S,
Kobayashi A,
Kitamura Y,
Kudoh I,
Wiener-Kronish J,
and
Sawa T.
Role of alveolar macrophages in initiation and regulation of inflammation in Pseudomonas aeruginosa pneumonia.
Infect Immun
66:
3164-3169,
1998
27.
Lahti, A,
Lahde M,
Kankaanranta H,
and
Moilanen E.
Inhibition of extracellular signal-regulated kinase suppresses endotoxin-induced nitric oxide synthesis in mouse macrophages and in human colon epithelial cells.
J Pharmacol Exp Ther
294:
1188-1194,
2000
28.
Laskin, DL,
and
Pendino KJ.
Macrophages and inflammatory mediators in tissue injury.
Annu Rev Pharmacol Toxicol
35:
655-677,
1995[ISI][Medline].
29.
Laskin, DL,
Sunil V,
Guo Y,
Heck DE,
and
Laskin JD.
Increased nitric oxide synthase in the lung after ozone inhalation is associated with activation of NF-kappa B.
Environ Health Perspect
5:
1175-1178,
1998.
30.
Lassus, P,
Wolff H,
and
Andersson S.
Cyclooxygenase-2 in human perinatal lung.
Pediatr Res
47:
602-605,
2000
31.
Marletta, MA,
Yoon PS,
Iyengar R,
Leaf CD,
and
Wishnok JS.
Macrophage oxidation of L-arginine to nitrite and nitrate: nitric oxide is an intermediate.
Biochemistry
27:
8706-8711,
1988[ISI][Medline].
32.
McRitchie, DI,
Isowa N,
Edelson JD,
Xavier AM,
Cai L,
Man HY,
Wang YT,
Keshavjee SH,
Slutsky AS,
and
Liu M.
Production of tumor necrosis factor alpha by primary cultured rat alveolar epithelial cells.
Cytokine
12:
644-654,
2000[ISI][Medline].
33.
Moncada, S,
Palmer RM,
and
Higgs EA.
Nitric oxide: physiology, pathophysiology, and pharmacology.
Pharmacol Rev
43:
109-142,
1991[ISI][Medline].
34.
Munir, I,
Fukunaga K,
Miyazaki K,
Okamura H,
and
Miyamoto E.
Mitogen-activated protein kinase activation and regulation of cyclooxygenase 2 expression by platelet-activating factor and hCG in human endometrial adenocarcinoma cell line HEC-1B.
J Reprod Fertil
117:
49-59,
1999[Abstract].
35.
Murphy, WJ.
Transcriptional regulation of the genes encoding nitric oxide synthase.
In: Cellular and Molecular Biology of Nitric Oxide. New York: Dekker, 1999, p. 1-56.
36.
O'Banion, MK.
Cyclooxygenase-2: molecular biology, pharmacology, and neurobiology.
Crit Rev Neurobiol
13:
45-82,
1999[ISI][Medline].
37.
Pece, S,
Chiariello M,
Murga C,
and
Gutkind JS.
Activation of the protein kinase Akt/PKB by the formation of E-cadherin-mediated cell-cell junctions. Evidence for the association of phosphatidyl inositol 3-kinase with the E-cadherin adhesion complex.
J Biol Chem
274:
19347-19351,
1999
38.
Pendino, KJ,
Laskin JD,
Shuler RL,
Punjabi CJ,
and
Laskin DL.
Enhanced production of nitric oxide by rat alveolar macrophages after inhalation of a pulmonary irritant is associated with increased expression of nitric oxide synthase.
J Immunol
151:
7196-7205,
1993
39.
Peters-Golden, M,
and
Feyssa A.
Transcellular eicosanoid synthesis in cocultures of alveolar epithelial cells and macrophages.
Am J Physiol Lung Cell Mol Physiol
264:
L438-L447,
1993
40.
Punjabi, CJ,
Laskin JD,
Pendino KJ,
Goller NL,
Durham SK,
and
Laskin DL.
Production of nitric oxide by rat type II pneumocytes: increased expression of inducible nitric oxide synthase following inhalation of a pulmonary irritant.
Am J Respir Cell Mol Biol
11:
165-172,
1994[Abstract].
41.
Seeger, W,
Walter H,
Suttorp N,
Muhly M,
and
Bhakdi S.
Thromboxane-mediated hypertension and vascular leakage evoked by low doses of Escherichia coli hemolysin in rabbit lungs.
J Clin Invest
84:
220-227,
1989[ISI][Medline].
42.
Shukla, A,
Timblin C,
BeruBe K,
Gordon T,
McKinney W,
Driscoll K,
Vacek P,
and
Mossman BT.
Inhaled particulate matter causes expression of nuclear factor (NF)-kappaB-related genes and oxidant-dependent NF-kappaB activation in vitro.
Am J Respir Cell Mol Biol
23:
182-187,
2000
43.
Stringer, B,
and
Kobzik L.
Environmental particulate-mediated cytokine production in lung epithelial cells (A549): role of preexisting inflammation and oxidant stress.
J Toxicol Environ Health
55:
31-44,
1998[ISI].
44.
Togashi, H,
Sasaki M,
Frohman E,
Taira E,
Ratan RR,
Dawson TM,
and
Dawson VL.
Neuronal (type I) nitric oxide synthase regulates nuclear factorB activity and immunologic (type II) nitric oxide synthase expression.
Proc Natl Acad Sci USA
94:
2676-2680,
1997
45.
Ueki, K,
Yamamoto-Honda R,
Kaburagi Y,
Yamauchi T,
Tobe K,
Burgering BM,
Coffer PJ,
Komuro I,
Akanuma Y,
Yazaki Y,
and
Kadowaki T.
Potential role of protein kinase B in insulin-induced glucose transport, glycogen synthesis, and protein synthesis.
J Biol Chem
273:
5315-5322,
1998
46.
Van der Vliet, A,
and
Cross CE.
Oxidants, nitrosants, and the lung.
Am J Med
109:
398-421,
2000[ISI][Medline].
47.
Vane, JR,
Bakhle YS,
and
Botting RM.
Cyclooxygenases 1 and 2.
Annu Rev Pharmacol Toxicol
38:
97-120,
1998[ISI][Medline].
48.
Walmrath, D,
Ghofrani HA,
Rosseau S,
Schutte H,
Cramer A,
Kaddus W,
Grimminger F,
Bhakdi S,
and
Seeger W.
Endotoxin "priming" potentiates lung vascular abnormalities in response to Escherichia coli hemolysin: an example of synergism between endo- and exotoxin.
J Exp Med
180:
1437-1443,
1994[Abstract].
49.
Ward, PA.
Phagocytes and the lung.
Ann NY Acad Sci
832:
304-310,
1997[ISI][Medline].
50.
Wardlaw, SA,
March TH,
and
Belinsky SA.
Cyclooxygenase-2 expression is abundant in alveolar type II cells in lung cancer-sensitive mouse strains and in premalignant lesions.
Carcinogenesis
21:
1371-1377,
2000
51.
Watanabe, K,
Kazakova I,
Furniss M,
and
Miller SC.
Dual activity of pyrrolidine dithiocarbamate on kappa B-dependent gene expression in U937 cells. I. Regulation by the phorbol ester TPA.
Cell Signal
11:
479-489,
1999[ISI][Medline].
52.
Weinstein, SL,
Finn AJ,
Dave SH,
Meng F,
Lowell CA,
Sanghera JS,
and
DeFranco AL.
Phosphatidyl inositol 3-kinase and mTOR mediate lipopolysaccharide-stimulated nitric oxide production in macrophages via interferon-beta.
J Leukoc Biol
67:
405-414,
2000[Abstract].
53.
Wizemann, TM,
Gardner CR,
Laskin JD,
Quinones S,
Durham SK,
Goller NL,
Ohnishi ST,
and
Laskin DL.
Production of nitric oxide and peroxynitrite in the lung during acute endotoxemia.
J Leukoc Biol
56:
759-768,
1994[Abstract].
54.
Wizemann, TM,
and
Laskin DL.
Enhanced phagocytosis, chemotaxis, and production of reactive oxygen intermediates by interstitial lung macrophages following acute endotoxemia.
Am J Respir Cell Mol Biol
11:
358-365,
1994[Abstract].
55.
Wymann, MP,
Sozzani S,
Altruda F,
Mantovani A,
and
Hirsch E.
Lipids on the move: phosphoinositide 3-kinases in leukocyte function.
Immunol Today
21:
260-264,
2000[ISI][Medline].
56.
Xavier, AM,
Isowa N,
Cai L,
Dziak E,
Opas M,
McRitchie DI,
Slutsky AS,
Keshavjee SH,
and
Liu M.
Tumor necrosis factor-alpha mediates lipopolysaccharide-induced macrophage inflammatory protein-2 release from alveolar epithelial cells. Autoregulation in host defense.
Am J Respir Cell Mol Biol
21:
510-520,
1999
57.
Zhao, MQ,
Stoler MH,
Liu AN,
Wei B,
Soguero C,
Hahn YS,
and
Enelow RI.
Alveolar epithelial cell chemokine expression triggered by antigen-specific cytolytic CD8(+) T cell recognition.
J Clin Invest
106:
R49-R58,
2000
58.
Zsengeller, Z,
Otake K,
Hossain SA,
Berclaz PY,
and
Trapnell BC.
Internalization of adenovirus by alveolar macrophages initiates early proinflammatory signaling during acute respiratory tract infection.
J Virol
74:
9655-9667,
2000