1 Department of Biochemistry, University of Texas Health Center, Tyler, Texas 75708; and 2 School of Medicine, Cardiovascular Research Institute, University of California, San Francisco, California 94143-0130
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The formation of
2-macroglobulin (
2-M)/interleukin-8
(IL-8) complexes may influence the biological activity of IL-8 and the
quantitative assessment of IL-8 activity. Therefore, in this study,
concentrations of free IL-8 and IL-8 complexes with
2-M were measured in pulmonary edema fluid samples from patients with acute
lung injury/acute respiratory distress syndrome (ALI/ARDS) and compared
with control patients with hydrostatic pulmonary edema. Patients with
ALI/ARDS had significantly higher concentrations of
2-M
(P < 0.01) as well as
2-M/IL-8
complexes (P < 0.05). Because a substantial amount of
IL-8 is complexed to
2-M, standard assays of free IL-8
may significantly underestimate the concentration of biologically
active IL-8 in the distal air spaces of patients with ALI/ARDS.
Furthermore, IL-8 bound to
2-M retained its biological activity, and this fraction of IL-8 was protected from proteolytic degradation. Thus complex formation may modulate the acute inflammatory process in the lung.
2-M in pulmonary edema fluid; neutrophils; IL-8 receptors; specific binding
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
ACUTE LUNG INJURY and
acute respiratory distress syndrome (ALI/ARDS) are characterized by
diffuse lung injury resulting in deterioration of lung function. Due to
an increase in capillary-alveolar membrane permeability,
2-macroglobulin (
2-M) translocates into the air spaces in patients with ALI/ARDS (30, 32).
2-M is a proteinase inhibitor that exists both in a
"native" (or "slow") and modified (or "fast") form.
This latter form of
2-M migrates faster than native
2-M during electrophoresis (9). Slow
(native)
2-M displays anti-proteinase activity. The fast
or inactive form of
2-M is generated on the reaction
with neutrophil elastase, a product of the neutrophils that accumulates
in the alveolar space in patients with ALI/ARDS (29, 31).
2-M binds several cytokines, including interleukin-8
(IL-8) (12, 14, 17). IL-8 is a potent neutrophil
attractant and activator (23). Several studies have
demonstrated that high concentrations of IL-8 are present in
bronchoalveolar lavage (BAL) and pulmonary edema fluids from patients
with ALI/ARDS (5, 7, 18-20). Furthermore, a
significant fraction of IL-8 in BAL fluid is associated with
2-M (14). IL-8 binds only to fast (methylamine-treated)
2-M. [Methylamine is routinely
used to convert slow (native)
2-M to fast form
(9).] In addition, in vitro both IL-8 and
2-M/IL-8 complexes bind to specific receptors for IL-8
on human neutrophils with similar affinity (13).
Most of 2-M in BAL fluid of patients with ALI/ARDS is
associated with neutrophil elastase (fast form) (32).
Therefore, we hypothesized that lower levels of active
2-M were present in pulmonary edema fluid of patients
with ALI/ARDS than in patients with hydrostatic pulmonary edema.
Because IL-8 binds to the inactive, fast form of
2-M, we
also hypothesized that the levels of
2-M/IL-8 complexes
would be increased in ALI/ARDS patients compared with control patients
with hydrostatic pulmonary edema. Furthermore, we wanted to test the
hypothesis that the IL-8 bound to
2-M in pulmonary edema
fluid of ALI/ARDS patients is biologically active. In contrast to our
previous studies using BAL fluid from patients with ALI/ARDS and from
healthy volunteers, we used undiluted pulmonary edema fluid in this
study because pulmonary edema fluid reflects the actual lung
environment more accurately than BAL fluid. Because BAL fluids from
individual patients are diluted, interpretation of the data is also
somewhat difficult. In addition, we compared the interaction between
IL-8 and
2-M in pulmonary edema fluids from patients
with ALI/ARDS and from patients with hydrostatic edema, an ideal group
of control patients who are ventilated and critically ill but have
pulmonary edema primarily due to elevated pulmonary vascular pressure
(28). Furthermore, because of a sustained inflammatory
response in the latter group, no significant increase in concentrations
of IL-8 and
2-M is expected (25, 28).
![]() |
MATERIALS AND METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Human subjects.
All studies involving human blood and pulmonary edema fluid were
approved by the Human Subjects Investigation Committees of the
University of California, San Francisco, and the University of Texas
Health Center at Tyler. Informed written consent was obtained from all
the subjects or their representatives. ALI was diagnosed according to
the following criteria: 1)
PaO2-to-FIO2 ratio 300
mmHg, 2) bilateral infiltrates on the chest radiograph, and
3) a pulmonary artery wedge pressure of
18 mmHg and/or no clinical evidence of elevated left atrial pressure (1).
Hydrostatic pulmonary edema was defined as published before
(28). As in our prior studies (28), the
definition of hydrostatic edema was based on clinical evidence of
cardiac dysfunction from an acute myocardial infarction, exacerbation
of chronic heart failure, or volume overload with either a pulmonary
arterial wedge pressure >18 mmHg or a two-dimensional echocardiogram
demonstrating a reduction in the left ventricular ejection fraction
plus the presence of a transudative pulmonary edema fluid-to-plasma
total protein ratio <0.65. Pulmonary edema fluid samples from patients
with ALI/ARDS or hydrostatic pulmonary edema were obtained as
previously described (30). Briefly, pulmonary edema fluid
samples were obtained within 15 min of intubation and mechanical
ventilation. A 14-French suction catheter (Becton-Dickinson, Lincoln
Park, NJ) was passed through the endotracheal tube and wedged into the
distal airways. Then, edema fluid samples were suctioned gently through
the inserted catheter. The samples were centrifuged at 3,000 g for 10 min, and the supernatants were stored at
70°C
until use.
Measurement of total protein. The total protein concentration in the edema fluid samples was measured by using Coomassie Plus protein assay reagent (Pierce, Rockford, IL) according to the manufacturer's instructions. For the measurement of edema fluid-to-plasma protein concentration ratios, protein concentration was measured by the biuret method as previously described (28).
Measurement of concentration of 2-M.
The concentration of
2-M in the edema fluid samples was
measured in an ELISA assay as previously described (2,
14).
Visualization of different forms of 2-M in the
edema fluid samples (electrophoresis I).
To establish the state of
2-M (slow vs. fast), pulmonary
edema fluid samples were subjected to nondenaturing polyacrylamide gel
electrophoresis (5% Tris-borate). The gels were then stained with
Coomassie blue.
Measurement of slow/native 2-M (trypsin binding
assay).
To calculate the amount of slow or native form,
2-M was
tested for trypsin binding activity by the method of Ganrot
(8). The activity of trypsin (Sigma, St. Louis, MO) was
determined by active site titration with the substrate,
p-nitrophenyl-p'-guanidinobenzoate hydrochloride
(4).
Measurement of the quantity of 2-M bound to
neutrophil elastase (
2-M/elastase complexes) in the
edema fluid samples.
The concentration of neutrophil elastase bound to
2-M in
pulmonary edema fluid was determined by measuring the rate of
hydrolysis of the elastase substrate MeOSuc-Ala-Ala-Pro-Val-NH-Np in
the presence and absence of an
1-proteinase inhibitor (a
generous gift from Dr. Hall James, the University of Texas Health
Center, Tyler, TX) (21).
Measurement of concentration of IL-8. IL-8 concentration in the edema fluid samples was measured in an ELISA assay developed in our laboratory by using a matched antibody pair according to the manufacturer's protocol (R&D Systems, Minneapolis, MN).
Measurement of concentration of 2-M/IL-8
complexes.
The concentration of
2-M/IL-8 complexes in the edema
fluid samples was measured by using a specific ELISA assay developed in
our laboratory (14).
Visualization of binding of 125I-recombinant human
IL-8 to 2-M in the edema fluid samples (electrophoresis
II).
Recombinant human IL-8 (rhIL-8; R&D Systems) was labeled with
125I (11). Pulmonary edema fluid samples were
incubated with labeled IL-8, and complexes of 125I-rhIL-8
with
2-M were detected by nondenaturing polyacrylamide gel electrophoresis (5% Tris-borate) and autoradiography
(22). In this type of electrophoresis only
2-M bands can be detected using Coomassie blue stain
(see Fig. 1). When samples are incubated with 125I-rhIL-8, radioactive bands are visualized by
autoradiography. These bands represent 125I-rhIL-8 bound to
2-M and migrate as does
2-M alone.
|
Purification of 2-M/IL-8 complexes (gel filtration
chromatography).
To purify
2-M/IL-8 complexes, we separated the pulmonary
edema fluid samples on an HPLC gel filtration column, TSK-250. PBS was
used as elution buffer at a flow rate of 0.25 ml/min, and the fractions
were analyzed using IL-8 ELISA.
Preparation of neutrophils. Human neutrophils from healthy volunteers were separated by dextran sedimentation and erythrocyte lysis by the method of Boyum (3). The purity of neutrophils was usually 80-90%.
Competition between purified 2-M/IL-8 complexes
and 125I-labeled rhIL-8 for binding to IL-8 receptors on
neutrophils (binding studies).
Binding studies were performed utilizing neutrophils suspended in PBS
containing 1% BSA. The cells (1 × 106) were
incubated with 125I-labeled rhIL-8 in the presence or
absence of different concentrations of unlabeled rhIL-8 or purified
2-M/IL-8 complexes for 90 min at 4°C to reach
equilibrium and then centrifuged. The pellet ("bound" counts) and
supernatant ("free" counts) were counted in a gamma radiation
spectrometer (14). In some experiments, we treated the
samples with human neutrophil elastase (Elastin Products, Owensville,
MO) or incubated with goat anti-human
2-M IgG (ICN Pharmaceuticals, Costa Mesa, CA) before adding 125I-labeled
rhIL-8.
Measurement of activity of purified 2-M/IL-8
complexes (neutrophil chemotaxis).
Chemotactic activity of neutrophils (0.4 × 106/chemotactic chamber) was assessed by the leading front
method of Zigmond and Hirsch as previously described (14,
33).
Binding of IL-8 to elastase-treated commercial
2-M.
2-M (10 µg) obtained from Biodesign International
(Kennebunk, ME) was incubated with human neutrophil elastase (Elastin
Products) and 125I-labeled rhIL-8 for 0, 1.5, 3, 6, and
24 h in the presence or absence of the elastase inhibitor
phenylmethylsulfonyl fluoride (Sigma). The samples were electrophoresed
on a native 5% gel. Gels were then dried for autoradiography, and the
autoradiographs were scanned.
Affinity of IL-8 binding to elastase-treated commercial
2-M.
Different concentrations of elastase-treated
2-M were
incubated with rhIL-8 overnight at 25°C. The samples were
electrophoresed on native 5% gels or SDS-polyacrylamide 4-20%
gradient gels. Gels were dried and subjected to autoradiography. In
addition, to estimate the amount of IL-8 bound to
2-M,
autoradiographs of the gels were scanned. The dissociation constant
(Kd) was calculated as previously described
(14). Briefly, the amount of noncovalently bound IL-8 was
calculated by subtracting the amount of IL-8 detected in
SDS-electrophoresis from the amount detected in native gel electrophoresis. Furthermore, the Kd for
noncovalent binding can be expressed as: I/MI = Kd(1/M), where M is
2-M, I is
IL-8, and MI is a reversible (noncovalent)
2-M/IL-8 complex.
Activity of IL-8 bound to elastase-treated commercial
2-M (neutrophil enzyme release).
The assay was performed in a 96-well plate, and 0.6 × 106 cells were added to each well. Myeloperoxidase was
measured by determining the change in absorbance of tetramethyl
benzidine (Sigma) at 450 nm in the presence of hydrogen peroxide as
previously described (26).
N-formylmethionyl-leucyl-phenylalanine (Sigma) was used as a
positive control.
Statistical analysis. Comparisons between groups were done using the Student's t-test or the nonparametric Mann-Whitney rank sum test when the data sets were not normally distributed and Fisher's exact test. Results are presented as means ± SD. All statistics were performed using SIGMASTAT (SPSS Science, Chicago, IL).
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Patients with ALI/ARDS and hydrostatic pulmonary edema.
Nineteen patients with ALI/ARDS and seven patients with hydrostatic
pulmonary edema were included in this study. The characteristics of the
two patient groups are outlined in Table
1. The mean severity of illness
(simplified acute physiology score) and the lung injury score were
similar for the two groups. This has been a common finding in many of
our studies (27). In addition, there was a higher
incidence of sepsis and renal failure in the ALI/ARDS patients (Table
1).
|
Edema fluid/plasma protein concentration ratio. The edema fluid-to-plasma protein concentration ratio was significantly higher in patients with ALI/ARDS compared with patients with hydrostatic edema (0.98 ± 0.21 and 0.63 ± 0.28) (P < 0.01). The total protein concentration in the edema fluid was also increased in ALI/ARDS patients compared with patients with hydrostatic edema (4.7 ± 1.6 and 3.0 ± 0.6 g/100 ml, respectively) (P < 0.05).
2-M in pulmonary edema fluid.
The different forms of
2-M present in pulmonary edema
fluid of patients with ALI/ARDS and patients with hydrostatic edema are
depicted in Fig. 1. Samples were chosen according to their ability to
inhibit trypsin. Edema fluid samples from three different patients
untreated [lanes 2 (ALI/ARDS), 4 (ALI/ARDS), and
6 (hydrostatic pulmonary edema)] and the same edema fluid
samples treated with methylamine [lanes 3 (ALI/ARDS),
5 (ALI/ARDS), and 7 (hydrostatic pulmonary
edema)] were run on a native gel. Samples containing slow or native
2-M (capable of interacting with trypsin or methylamine) are shown in lanes 2 and 4, and a sample
containing both slow and fast
2-M is shown in lane
6. Patients with ALI/ARDS had a higher total
2-M concentration in edema fluid compared with patients with hydrostatic edema (P < 0.01) (Fig.
2A) due to the increase in
capillary-alveolar permeability. As hypothesized, due to differences in
the nature of pulmonary inflammation, the relative amount of slow or
native
2-M (expressed as a percentage of total
2-M) was decreased in patients with ALI/ARDS. Pulmonary
edema fluid from patients with ALI/ARDS contained significantly less
slow or native
2-M (expressed as a percentage of total
2-M) than did pulmonary edema fluid from hydrostatic
edema patients (P < 0.001) (Fig. 2B). In
addition, the quantity of
2-M bound to neutrophil elastase or fast
2-M (expressed as a percentage of total
2-M) was higher in patients with ALI/ARDS compared with
patients with hydrostatic edema (34 ± 33% vs. 8 ± 19%), though
that difference did not quite reach statistical significance
(P = 0.06). Because the total
2-M
concentration was significantly higher in patients with ALI/ARDS,
the actual concentration of the slow form did not differ between
patient groups (0.33 ± 0.19 and 0.31 ± 0.20 mg/ml, for
ALI/ARDS and hydrostatic edema groups, respectively) (P = 0.83). However, the concentration of
2-M bound to
neutrophil elastase was significantly increased in patients with
ALI/ARDS compared with patients with hydrostatic edema (0.28 ± 0.29 and 0.03 ± 0.06 mg/ml, respectively) (P < 0.05).
|
Interaction of IL-8 with 2-M.
The pulmonary edema fluid concentrations of IL-8 were not significantly
different between the two groups of patients (P = 0.15), although in patients with ALI/ARDS, levels of IL-8 showed a
tendency to increase (39 ± 38 and 17 ± 22 ng/ml,
respectively). However, the concentration of
2-M/IL-8 complexes was significantly higher in pulmonary
edema fluid from patients with ALI/ARDS (P < 0.05)
(Fig. 3). Similarly, comparison of the
ratios of
2-M/IL-8 complex concentrations to total
protein concentrations using Fisher's exact test
(
2-M/IL-8 complexes:total protein > 1.10 ng/mg)
showed that patients with ALI/ARDS (18:1) significantly differed from patients with hydrostatic pulmonary edema (4:3) (P < 0.05). The mean ratio was 0.81 ± 0.26 and 2.06 ± 0.60 ng/mg
for patients with ALI/ARDS and for patients with hydrostatic pulmonary
edema, respectively.
|
|
Interaction of IL-8 with elastase-modified 2-M in
vitro.
Because purified
2-M/IL-8 complexes contained elastase
(bound to
2-M), we studied the interaction of IL-8 with
2-M, which was treated with elastase in vitro. IL-8
bound to elastase-modified
2-M in a saturable manner,
and the calculated Kd was ~6 × 10
8 M. We also examined the effect of IL-8 in complex
with elastase-modified human
2-M on the release of
myeloperoxidase, a marker of neutrophil activation (Fig.
5). The complexed IL-8 did not differ
from free IL-8 in its ability to release myeloperoxidase from human
neutrophils (P > 0.05). In addition,
2-M alone did not exhibit any activity (Fig. 5).
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The major findings of this study can be summarized as follows. In
patients with ALI/ARDS, the quantity of 2-M complexed
with elastase in pulmonary edema fluid was increased, and consequently the quantity of slow (native)
2-M was decreased. There
was a corresponding increase in the quantity of fast
2-M
in pulmonary edema fluid from patients with ALI/ARDS. The increase in
the fast form of
2-M may result in increased binding to
proinflammatory cytokines. Accordingly, as we hypothesized, there was a
significant increase in
2-M/IL-8 complexes in pulmonary
edema fluid from patients with ALI/ARDS compared with control patients
with hydrostatic edema. In addition, the results indicate that IL-8
complexed to
2-M remains biologically active. This is
the first study to describe the function of IL-8 complexed to
2-M in pulmonary edema fluid. In addition, this is the
first study to define the activity of IL-8 in
2-M/IL-8
complexes purified from pulmonary edema fluid. Thus our observations
are more closely related to in vivo conditions than our prior studies
of the in vitro activity of IL-8 (13-15).
An important feature of ALI/ARDS is that large proteins, such as
2-M, translocate across the injured endothelial and
epithelial barriers of the lung and accumulate in the air spaces
(10, 29). Wewers et al. (32) showed that the
majority (70%) of
2-M present in BAL fluid from
patients with ALI/ARDS is complexed to neutrophil elastase. However,
only 34% of the total
2-M was complexed with neutrophil
elastase in our study. The difference between the studies may be due to
the fact that the former used BAL fluid whereas our study used
pulmonary edema fluid. Furthermore, elastase complexed to
2-M retains its enzymatic activity. This form of
elastase was present in samples from five of seven patients with
ALI/ARDS but only in one of 13 normal volunteers (32). In
our study, neutrophil elastase complexed with
2-M was
detected in 13 of the 19 patients with ALI/ARDS. Thus a similar number
of patients with ALI/ARDS had the complexed elastase (70 vs. 68%,
respectively) in both studies.
The intensity and character of inflammation are quite different in
patients with ALI/ARDS and patients with hydrostatic pulmonary edema
(24). Accordingly, more patients with ALI/ARDS than with hydrostatic edema had elastase bound to 2-M (13 in 19 patients and 2 in 7 patients, respectively). In addition, 34% of the
total
2-M was complexed with neutrophil elastase in
patients with ALI/ARDS whereas only 8% was complexed in patients
with hydrostatic edema. The concentration of
2-M
associated with elastase was significantly higher in these patients
(P < 0.05). Furthermore, the activity of
2-M (the ability to inhibit trypsin) ranged from 47%
(%total) for ALI/ARDS to 85% (%total) for the hydrostatic edema
group. However, because of the increased permeability to protein in
patients with ALI/ARDS, the total amount of active
2-M
was similar in both groups of patients. The remaining
2-M (not active or complexed with elastase) could be
bound to other proteinases or modified by oxidation (25).
In agreement with our previous study (14), only a small
fraction of the total 2-M was associated with IL-8
(<1%). However, fast
2-M present in pulmonary edema
fluid was still able to bind IL-8. Accordingly, we found that the
extent of 125I-labeled rhIL-8 binding to pulmonary edema
fluid
2-M depended on the
2-M state (slow
vs. fast). Edema fluid samples that contained mostly native
2-M bound 125I-rhIL-8 only after treatment
with methylamine (IL-8 does not bind to the slow form)
(14). Furthermore, the concentration of the
2-M/IL-8 complexes was higher in patients with ALI/ARDS than in patients with hydrostatic edema (P < 0.05). To
determine whether the differences in
2-M/IL-8 complex
concentrations were due to augmented intra-alveolar production of
2-M versus translocation from the intravascular to the
intra-alveolar compartment, we also examined the
2-M/IL-8 complex concentration-to-total protein concentration ratios. The difference between ALI/ARDS and hydrostatic groups was still significant (P < 0.05).
Because 2-M complexed to IL-8 was associated with
elastase, the interaction between IL-8 and elastase-treated
2-M was also studied in vitro. We found for the first
time that IL-8 bound to elastase-modified
2-M in a
saturable manner in vitro, and the binding was of high affinity
compared with other cytokines (6). The calculated
Kd was ~6 × 10
8M. In
addition, IL-8 in complex with elastase-modified
2-M
retained its biological activity.
IL-8 is an important neutrophil chemoattractant in lung fluids from
patients with ALI/ARDS (19, 20). Several studies have indicated the potential use of IL-8 as a marker of the development or
outcome of ALI/ARDS (5, 7, 18-20). However, some
ELISA assays do not recognize IL-8 that is bound to 2-M
(14). The results of this study demonstrate that the IL-8
concentration in pulmonary edema fluid is at least two to three times
higher that that measured by ELISA assay. Furthermore, purified
2-M/IL-8 complexes displayed unchanged biological
activity (chemotactic activity). Also, IL-8 complexed to
2-M was protected from proteolytic degradation.
Therefore, when the appearance of
2-M/IL-8 complexes coincides with the influx of neutrophils, it may create a favorable environment for further neutrophil accumulation. This may explain why,
in patients at risk for ALI/ARDS who subsequently developed ALI/ARDS,
2-M/IL-8 complexes and neutrophil concentrations were correlated (P < 0.05; r2 = 1.00) (16).
On the other hand, our previous findings suggested that
2-M could be an important mediator of IL-8 clearance
(13, 15). Those studies indicated that alveolar
macrophages have receptors for
2-M but not for IL-8. In
addition, we found that complexes between rhIL-8 and fast human
2-M are cleared by human alveolar macrophages via
2-M receptors (13). Furthermore, the
instillation of IL-8 bound to the fast rabbit
-macroglobulin to the
rabbit lung abolished the influx of neutrophils induced by the
instillation of the same concentration of IL-8 alone (15).
These findings suggested that formation of
2-M/IL-8
complexes facilitates clearance of IL-8. Accordingly, we found that the
concentration of these complexes declined over time (between days
1 and 7 of ALI/ARDS) but interestingly only in ALI/ARDS
survivors. This finding was independent of the decline in total protein
concentration (14, 16). Thus the data in this study,
coupled with our earlier work, indicate that
2-M/IL-8
complexes may modulate the acute inflammation in patients with ALI/ARDS
since
2-M may affect degradation and clearance of
proinflammatory IL-8. On the other hand, if availability of
2-M receptors on macrophages is decreased, then
2-M/IL-8 complexes could enhance the inflammatory
process in the lung further by triggering the activation of neutrophils.
In summary, IL-8 in complex with 2-M retains its
biological activity. The complexes thus bind to IL-8 receptors on
neutrophils. The complexes are also cleared by alveolar macrophages
(via
2-M receptors). Therefore, the fate of these
complexes depends on the immediate environment surrounding them, e.g.,
cell type and the availability of receptors.
![]() |
ACKNOWLEDGEMENTS |
---|
This work was supported by National Heart, Lung, and Blood Institute Grants HL-56768 (A. K. Kurdowska) and HL-51856 (M. A. Matthay).
![]() |
FOOTNOTES |
---|
Address for reprint requests and other correspondence: A. Kurdowska, Dept. of Biochemistry, Univ. of Texas Health Center, 11937 US Hwy. 271, Tyler, TX 75708-3154 (E-mail: anna.kurdowska{at}uthct.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.
First published December 21, 2001;10.1152/ajplung.00378.2001
Received 24 September 2001; accepted in final form 15 December 2001.
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
1.
Bernard, GR,
Artigas A,
Brigham KL,
Carlet J,
Falke K,
Hudson L,
Lamy M,
LeGall JR,
Morris A,
and
Spragg R.
Report of the American-European Consensus conference on acute respiratory distress syndrome: definitions, mechanisms, relevant outcomes, and clinical trial coordination. Consensus Committee.
J Crit Care
9:
72-81,
1994[ISI][Medline].
2.
Bonner, JC,
Goodell AL,
Lasky JA,
and
Hoffman MR.
Reversible binding of platelet-derived growth factor-AA, -AB, and -BB isoforms to a similar site on the "slow" and "fast" conformations of alpha-2-macroglobulin.
J Biol Chem
267:
12837-12844,
1992
3.
Boyum, A.
Isolation of mononuclear cells and granulocytes from human blood. Isolation of mononuclear cells by one centrifugation and of granulocytes by combining centrifugation and sedimentation at 1 g.
Scand J Clin Lab Invest Suppl
97:
77-89,
1968[Medline].
4.
Chase, T,
and
Shaw EP.
P-nitrophenyl-p'-guanidinobenzoate HCl: a new active site titrant for trypsin.
Biochem Biophys Res Commun
29:
508-514,
1967[ISI].
5.
Chollet-Martin, S,
Montravers P,
Gibert C,
Elbim C,
Desmonts JM,
Fagon JY,
and
Gougerot-Pocidalo MA.
High levels of interleukin-8 in the blood and alveolar spaces of patients with pneumonia and adult respiratory distress syndrome.
Infect Immun
61:
4553-4559,
1993[Abstract].
6.
Crookston, KP,
Webb DJ,
Wolf BB,
and
Gonias SL.
Classification of 2-macroglobulin-cytokine interactions based on affinity of noncovalent association in solution under apparent equilibrium conditions.
J Biol Chem
269:
1533-1540,
1994
7.
Donnelly, SC,
Strieter RM,
Kunkel SL,
Walz A,
Robertson CR,
Carter DC,
Grant IS,
Pollok AJ,
and
Haslett C.
Interleukin-8 and development of adult respiratory distress syndrome in at-risk patient groups.
Lancet
341:
643-647,
1993[ISI][Medline].
8.
Ganrot, PO.
Determination of 2-macroglobulin as trypsin protein esterase.
Clin Chim Acta
14:
493-501,
1966[ISI][Medline].
9.
Gonias, SL,
Reynolds JA,
and
Pizzo SV.
Physical properties of human 2-macroglobulin following reaction with methylamine and trypsin.
Biochim Biophys Acta
705:
306-314,
1982[ISI][Medline].
10.
Holter, JF,
Weiland JE,
Pacht ER,
Gadek JE,
and
Davis WB.
Protein permeability in the adult respiratory distress syndrome. Loss of size selectivity of the alveolar epithelium.
J Clin Invest
78:
1513-1522,
1986[ISI][Medline].
11.
Hunter, WM,
and
Greenwood FC.
Preparation of iodine-131 labelled human growth hormone of high specific activity.
Nature
194:
495-496,
1962[ISI].
12.
James, K.
Interactions between cytokines and alpha-2-macroglobulin.
Immunol Today
11:
163-166,
1990[ISI][Medline].
13.
Kurdowska, A,
Alden SM,
Noble JM,
Stevens MD,
and
Carr FK.
Involvement of 2-macroglobulin receptor in clearance of interleukin-8-
2-macroglobulin complexes by human alveolar macrophages.
Cytokine
12:
1046-1053,
2000[ISI][Medline].
14.
Kurdowska, A,
Carr FK,
Stevens MD,
Baughman RP,
and
Martin TR.
Studies on the interaction of interleukin-8 with human plasma 2-macroglobulin. Evidence for the presence of IL-8 complexed to
2-macroglobulin in lung fluids of patients with the adult respiratory distress syndrome.
J Immunol
158:
1930-1940,
1997[Abstract].
15.
Kurdowska, A,
Fujisawa N,
Peterson B,
Carr FK,
Noble JM,
Alden SM,
Miller EJ,
and
Teodorescu M.
Specific binding of IL-8 to rabbit -macroglobulin modulates IL-8 function in the lung.
Inflamm Res
49:
591-599,
2000[ISI][Medline].
16.
Kurdowska, A,
Noble JM,
Steinberg KP,
Ruzinski J,
and
Martin TR.
IL-8-binding proteins in alveolar fluid from patients with the acute respiratory distress syndrome (ARDS) (Abstract).
FASEB J
12:
A879,
1998[ISI].
17.
LaMarre, J,
Wollenberg GK,
Gonias SL,
and
Hayes MA.
Biology of disease: cytokine binding and clearance properties of proteinase-activated alpha-2-macroglobulins.
Lab Invest
65:
3-14,
1991[ISI][Medline].
18.
Meduri, GU,
Kohler G,
Headly S,
Tolley E,
Stentz F,
and
Postlethwaite A.
Inflammatory cytokines in the BAL of patients with ARDS. Persistent elevation over time predicts poor outcome.
Chest
108:
1303-1314,
1995
19.
Miller, EJ,
Cohen AB,
and
Matthay MA.
Increased interleukin-8 concentrations in the pulmonary edema fluid of patients with acute respiratory distress syndrome from sepsis.
Crit Care Med
24:
1448-1454,
1996[ISI][Medline].
20.
Miller, EJ,
Cohen AB,
Nagao S,
Griffith D,
Maunder RJ,
Martin TR,
Weiner-Kronish JP,
Sticherling M,
Christophers E,
and
Matthay MA.
Elevated levels of NAP-1/interleukin-8 are present in the airspaces of patients with the adult respiratory distress syndrome and are associated with increased mortality.
Am Rev Respir Dis
146:
427-432,
1992[ISI][Medline].
21.
Nakajima, K,
Powers JC,
Ashe BM,
and
Zimmerman M.
Mapping the extended substrate binding site of cathepsin G and human leukocyte elastase. Studies with peptide substrates related to the alpha 1-protease inhibitor reactive site.
J Biol Chem
254:
4027-4032,
1979[ISI][Medline].
22.
Nelles, LP,
Hall PK,
and
Roberts RC.
Human alpha2-macroglobulin: studies on the electrophoretic heterogeneity.
Biochim Biophys Acta
623:
46-56,
1980[ISI][Medline].
23.
Oppenheim, JJ,
Zachariae COC,
Mukaida N,
and
Matsushima K.
Properties of the novel proinflammatory supergene "intercrine" cytokine family.
Annu Rev Immunol
9:
617-648,
1991[ISI][Medline].
24.
Pugin, J,
Verghese G,
Widmer M-C,
and
Matthay MA.
The alveolar space is the site of intense inflammatory and profibrotic reactions in the early phase of acute respiratory distress syndrome.
Crit Care Med
27:
304-312,
1999[ISI][Medline].
25.
Reddy, VY,
Desrochers PE,
Pizzo SV,
Gonias SL,
Sahakian JA,
Levine RL,
and
Weiss SJ.
Oxidative dissociation of human 2-macroglobulin tetramers into dysfunctional dimers.
J Biol Chem
269:
4683-4691,
1994
26.
Suzuki, K,
Ota H,
Sasagawa S,
Sakatani T,
and
Fujikura T.
Assay method for myeloperoxidase in human polymorphonuclear leukocytes.
Anal Biochem
132:
345-352,
1983[ISI][Medline].
27.
Verghese, G,
McCormick-Shannon K,
Mason RJ,
and
Matthay MA.
Hepatocyte growth factor and keratinocyte growth factor in the pulmonary edema fluid of patients with acute lung injury.
Am J Respir Crit Care Med
158:
386-394,
1998
28.
Verghese, GM,
Ware LB,
Matthay BA,
and
Matthay MA.
Alveolar epithelial fluid transport and the resolution of clinically severe hydrostatic pulmonary edema.
J Appl Physiol
87:
1301-1312,
1999
29.
Ware, LB,
and
Matthay MA.
The acute respiratory distress syndrome.
N Engl J Med
342:
1334-1349,
2000
30.
Ware, LB,
and
Matthay MA.
Alveolar fluid clearance is impaired in the majority of patients with acute lung injury and the acute respiratory syndrome.
Am J Respir Crit Care Med
163:
1376-1383,
2001
31.
Weiland, JE,
Davis WB,
Holter JF,
Mohammed JR,
Dorinsky PM,
and
Gadek JE.
Lung neutrophils in the adult respiratory distress syndrome. Clinical and pathological significance.
Am Rev Respir Dis
133:
218-225,
1986[ISI][Medline].
32.
Wewers, MD,
Herzyk DJ,
and
Gadek JE.
Alveolar fluid neutrophil elastase activity in the adult respiratory distress syndrome is complexed to alpha-2-macroglobulin.
J Clin Invest
82:
1260-1267,
1988[ISI][Medline].
33.
Zigmond, S,
and
Hirsch J.
Leukocyte locomotion and chemotaxis.
J Exp Med
137:
387-410,
1963[ISI][Medline].