| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Program in Cell Biology, Department of Pediatrics, National Jewish Medical and Research Center, Denver, CO 80206
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussion:References |
|---|
. To model the direct
effects of necrotic cells on macrophage cytokine production, we added
lysed or apoptotic neutrophils and lymphocytes to mouse and human
macrophages in the absence of serum to avoid complement activation. The
results confirmed the ability of lysed neutrophils, but not
lymphocytes, to significantly stimulate production of
macrophage-inflammatory protein 2 or IL-8, TNF-
, and IL-10.
Concomitantly, induction of TGF-1 by lysed neutrophils was
significantly lower than that observed for apoptotic cells. The
addition of selected serine protease inhibitors and anti-human
elastase Ab markedly reduced the proinflammatory effects, the lysed
neutrophils then behaving as an anti-inflammatory stimulus similar
to intact apoptotic cells. Separation of lysed neutrophils into
membrane and soluble fractions showed that the neutrophil membranes
behaved like apoptotic cells. Thus, the cytokine response seen when
macrophages were exposed to lysed neutrophils was largely due to
liberated proteases. Therefore, we suggest that anti-inflammatory
signals can be given by PtdSer-containing cell membranes, whether from
early apoptotic, late apoptotic, or lysed cells, but can be overcome by
proteases liberated during lysis. Therefore, the outcome of an
inflammatory reaction and the potential immunogenicity of Ags within
the damaged cell will be determined by which signals
predominate. |
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussion:References |
|---|
1 following exposure to
apoptotic cells (3, 4), and this could be mimicked by
PtdSer-containing liposomes and a mAb against a newly described PtdSer
receptor (5). By incubating macrophages so treated with
anti-TGF- Abs, the inflammatory response to LPS was restored,
suggesting that TGF-1 induced by apoptotic cells was a major cause
of the anti-inflammatory effect observed. Anti-IL-10 Abs were not
effective, and, in fact, IL-10 production was down-regulated during
exposure to apoptotic cells in the absence of serum (3),
although Voll et al. reported that IL-10 appeared to play a role in the
regulation of cytokine production by human monocytes following
interaction with apoptotic peripheral lymphocytes (6). In
fact, Freire-de-Lima and coworkers have shown that uptake of apoptotic
cells by macrophages fuels the growth of trypanosomes in Chagas’
disease, in a TGF-- and PGE2-dependent manner, thereby
promoting disease progression (7). PGE2 has
been reported to be released following the binding and uptake of
apoptotic cells by HMDM (3). By contrast, Uchimura,
Kurosaka, and coworkers have suggested that uptake of apoptotic cells
is proinflammatory (8, 9). As phagocytic targets, they
used apoptotic CTLL2 cells cultured in the absence of IL-2 for 12 or
28 h. Both populations contained high levels of necrotic cells, as
indicated by trypan blue and propidium iodide positivity, which might
explain the proinflammatory effects they observed. It is commonly believed that necrotic cells are proinflammatory. Certainly most pathological lesions characterized by necrosis are also characterized by inflammation. Stern and colleagues showed that following association with necrotic (postapoptotic) eosinophils, unstimulated HMDM produced equivalent amounts of thromboxane B2 and GM-CSF to those that had ingested opsonized eosinophils or opsonized zymosan; these results contrasted sharply with the lack of induction by apoptotic eosinophils (2). Therefore, it was important to determine whether necrotic cells had similar effects on stimulated macrophage production of cytokines, and whether the type of apoptotic cell affected the macrophage cytokine response. Therefore, we compared the direct effects of binding and/or uptake of apoptotic vs lysed neutrophils and lymphocytes on cytokine production by unstimulated or zymosan-stimulated macrophages. The experiments were performed in the absence of serum to rule out the potential contribution of complement fixation following exposure to intracellular organelles (10, 11).
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussion:References |
|---|
HMDM were cultured as described previously (3, 12). In brief, mononuclear cells were isolated from the blood of normal donors, and plated at 4 million/well in 24-well tissue culture plates. Lymphocytes were removed following incubation on tissue culture plates for 1 h in DMEM (Irvine Scientific, San Diego, CA). This method yielded 1.46 ± 0.5 macrophages per well. After washing, the macrophages were cultured for 7 days in X-Vivo (BioWhittaker, Walkersville, MD) containing 10% human serum pooled from five donors; the medium was changed once after the first 3 days of culture. Bone marrow cells were obtained from C3H/HeJ mice and cultured as described (13) in DMEM containing 10% heat-killed FCS and 10% L cell-conditioned medium as a source of M-CSF. Bone marrow-derived macrophages (BMDM) were used 5–7 days after isolation and culture.
Induction of apoptosis
Human neutrophils and the human T cell line Jurkat were used as apoptotic targets. Neutrophils were induced to undergo apoptosis by exposure to UV irradiation for 5 min followed by culture for 3 h, as described previously (3). Jurkat T cells were irradiated for 10 min and cultured for 3 h. Apoptosis was assessed by morphological examination of cytocentrifuged cells and by flow cytometry, using FITC-conjugated annexin V. For neutrophils, the average percent apoptosis was 74.3 ± 5.4 (SEM); for Jurkats, 75.3 ± 4.2 (SEM); trypan blue positivity was <4% for either population; propidium iodide positivity was <6%. Results of annexin V positivity were not significantly different from apoptosis as assessed by morphology (data not shown). For late apoptotic cells, human neutrophils were irradiated as above, but cultured for 24 h; this yielded populations of cells that were 95% annexin V positive, 45% trypan blue positive, and 65% propidium iodide positive.
Lysis
Human neutrophils and Jurkat T cells were rapidly frozen as cell pellets on dry ice, then stored at -70°C. They were thawed at room temperature without washing, and suspended in X-Vivo without serum before use. The average percent lysis, assessed by trypan blue positivity, for neutrophils was 92.6 ± 2.4% (SEM) and for Jurkat T cells 95.6 ± 1.4% (SEM). Staining with FITC-conjugated annexin V and propidium iodide revealed that 100% of each population were positive for both. One cycle of freeze/thaw was used to give intact but trypan blue-positive bodies. For preparation of membrane and cytosol fractions, the cells were subjected to five freeze-thaw cycles, homogenized in X-Vivo medium, and centrifuged at 100,000 x g. The membrane pellets or the membrane-free supernatant were added to macrophages as cell equivalents to compare them to the intact but leaky lysed cells. Membrane and cytosolic fractions were also made from apoptotic and viable granulocytes by homogenizing them in X-Vivo, and by ultracentrifugation.
Macrophage cytokine production
Macrophages were cultured in 24-well plates and each condition
was run in duplicate. Five million apoptotic or necrotic (lysed) cells
were added per well of macrophages for 1.5 h, then washed out.
Fresh X-Vivo medium without serum was added, and supernatants were
collected 24 h later. Replicate wells were used to assess uptake
of the phagocytic targets. For neutrophils, the monolayers were stained
for myeloperoxidase as previously described and shown; only those
macrophages that had engulfed neutrophils were scored as positive for
staining (3). Uptake of apoptotic neutrophils was
associated with intracellular staining of discrete intact bodies,
whereas uptake of necrotic (lysed) cells was associated with paler
staining intracellular bodies and with diffuse staining of the
macrophages. Uptake of lymphocytes was assessed by staining the
macrophage monolayers with a modified Wright’s Giemsa stain. For some
experiments, the lysed neutrophils were incubated with the macrophages
in the presence or absence of 100 µM PMSF (Sigma, St. Louis, MO), 500
µM 4-(2-aminoethyl) benzenesulfonylfluoride (AEBSF) (Calbiochem, La
Jolla, CA), 5 µg/ml aprotinin, 0.25 µg/ml leupeptin, 1 µg/ml
E-64, 40 µg/ml bestatin, 0.7 µg/ml pepstatin, and 15 µg/ml
calpain I inhibitor (Boehringer Mannheim, Indianapolis, IN),
anti-human neutrophil elastase, anti-human cathepsin G, and
isotype controls for 24 h before collection of supernatants for
evaluation of cytokine concentrations. Preliminary dose responses were
performed to insure a lack of toxicity to the macrophage monolayers.
Viability at the concentrations used was verified by trypan blue
concentration (
4% positive cells) and by preservation of the
stimulatory response to zymosan (assessed by measurement of
macrophage-inflammatory protein 2 (MIP2), TNF-, IL-10, and TGF-).
Anti-human elastase and anti-human cathepsin G Abs were purified
sheep IgG purchased from Cortex Biochem (San Leandro, CA), and were
used at 50 µg/ml. Zymosan (Sigma) was used as a stimulus for cytokine
production; HMDM were stimulated with 25 µg/ml and BMDM with 75
µg/ml. In some experiments, 0.01 U/ml purified human neutrophil
elastase and 5 U/ml purified human cathepsin G (both obtained from
Calbiochem) were added to determine their direct effects on macrophage
cytokine production. These concentrations were determined by lack of
effects on macrophage viability and peak of cytokine production.
Supernatants from duplicate wells were pooled, centrifuged to remove
cellular debris, and stored at -70°C until analyzed. As a control,
apoptotic or lysed cells were cultured for the same time periods in
X-Vivo medium without macrophages to determine whether they produced
cytokines. Neither apoptotic neutrophils nor apoptotic Jurkat T cells
produced significant levels of any of the cytokines tested.
Analysis of cytokines
Cytokines assessed included TGF-1, TNF-, IL-10, and either
MIP2 for mouse or IL-8 for human cells. Matched Ab pairs for the ELISAs
were purchased from R&D Systems (Minneapolis, MN). For TGF-1,
supernatants were activated with HCl before analysis. Cytokines levels
were detected following incubation with the biotinylated secondary Abs
by incubation with avidin-conjugated HRP, then tetramethylbenzidine and
H2O2 as substrate. The plates were read
in a Bio-Tek EL309 ELISA reader (Biotek Instruments, Winooska, VT), and
results were analyzed using the log/log curve fit option from Delta
Soft 3 (BioMetallics, Princeton, NJ).
Measurement of elastase
Freshly isolated neutrophils were suspended at 10 million per ml in X-Vivo, then immediately centrifuged, separated into pellet and supernatant, and frozen at -70°C. Early and late apoptotic neutrophils were prepared as described above except that they were cultured at 10 million per ml in X-Vivo medium, then centrifuged. The samples were frozen as pellets, and the supernatant was derived from culture. Lysed neutrophils were prepared by suspending neutrophils at 10 million per ml in X-Vivo and freezing at -70°C. On the day of the analysis, the pellets and supernatants were thawed. The necrotic cell preparations were thawed, then centrifuged to separate the material into pellet and supernatant. All cell pellets were solubilized in lysis buffer containing 50 mM Tris (pH 7.4), 1% Triton X-100, 0.25% deoxycholate, 150 mM NaCl, and 1 mM EGTA. For elastase analysis, 20 µl of solubilized pellet or supernatant was added in triplicate to 96-well ELISA plates, followed by 55 µl elastase reaction buffer (0.1 M HEPES, 0.5 M NaCl, 10% DMSO pH 7.5). Then, 150 µl of 0.2 M Elastase substrate I (methoxysuccinyl-ala-ala-pro-val-p-nitroanilide; Calbiochem) in elastase reaction buffer was added, and the samples were incubated at 37°C for 1 h. Elastase levels were determined by measuring absorbance at 410 nm, using serial dilutions of porcine elastase (Calbiochem) as standards. Specificity was determined by incubating the samples and standards in the presence or absence of Elastase Inhibitor III (methoxysuccinyl-ala-ala-pro-val-chloromethylketone (Calbiochem).
Statistical analysis
For
Figs. 1–3
and 6–7, data were evaluated by ANOVA and the
Tukey Kramer method. For Figs. 4 and 5, ANOVA and Dunnett’s method
were used, designating macrophages treated with lysed neutrophils as
the control for Fig. 4, and macrophages without target cells added as
the control for Fig. 5. Significance was set at p
< 0.05.
|
|
|
|
|
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussion:References |
|---|
, exposure to apoptotic human
neutrophils in the absence of serum had the expected effects: increased
production of TGF-1, with no stimulation of IL-10, TNF-, or a
chemokine (IL-8), and suppression of IL-8, TNF-, and IL-10 when
macrophages were costimulated with zymosan. In contrast, exposure to
lysed neutrophils induced significantly lower levels of TGF-1 than
apoptotic cells, and stimulated production of IL-10, TNF-, and IL-8
(p < 0.05). Although lysed neutrophils
stimulated proinflammatory cytokine production, the levels were lower
than those induced by zymosan. When the macrophages were stimulated
with zymosan to produce inflammatory cytokines, both apoptotic and
lysed neutrophils were able to significantly suppress TNF- and IL-10
production, although apoptotic cells were significantly more effective
(p < 0.05). Similar effects were seen when
mouse BMDM were used (Fig. 2). Percent
uptake of apoptotic cells by BMDM was 45 ± 7.8% and of lysed
cells 52.9 ± 11.2%. If the serine protease inhibitor PMSF was
added, the proinflammatory response of the unstimulated macrophage to
lysed neutrophils was significantly inhibited (Fig. 2A), as
was the production of IL-10 (p < 0.05). When
PMSF was added to the lysed neutrophils coincubated with
zymosan-stimulated macrophages, the lysed neutrophils behaved like
apoptotic cells (Fig. 2B). Treatment with PMSF did not alter
the effects of apoptotic cells or zymosan on macrophage cytokine
production. Lysed Jurkat T cells had the same effects on macrophage
cytokine production as apoptotic cells (Fig. 2). Both populations of
the lymphocytes inhibited stimulated production of MIP2, TNF-, and
IL-10, while stimulating TGF- production. These data suggested that
serine proteases liberated from the granulocyte were critical to the
induction of a proinflammatory response by lysed neutrophils.
Lysed neutrophils stimulated low levels of chemokines and TNF-, but
also exhibited some inhibitory effects on zymosan induction of these
cytokines. The effects of the lysed neutrophils were significantly
different from those of the apoptotic cells (p
< 0.05). This information, with the observation that PMSF treatment
inhibited the proinflammatory effects of the lysed cells, suggested the
hypothesis that the proinflammatory effects of serine proteases could
be opposed by the anti-inflammatory effects of the
PtdSer-containing lysed cell membranes. To determine whether this was
true, lysed neutrophils were homogenized and centrifuged to obtain a
crude membrane fraction and a cytosolic fraction; each of these were
added to mouse macrophages in the presence or absence of zymosan to
determine their effects on cytokine production. We also used membranes
and cytosol from lysed Jurkat cells. As shown in Fig. 3, the cytosolic fraction from
neutrophils contained the activity that stimulated MIP2, TNF-, and
IL-10. The membranes were anti-inflammatory as they induced the
secretion of TGF-, and inhibited zymosan-induced MIP2, TNF-, and
IL-10. We also used membrane and cytosolic fractions from viable and
apoptotic neutrophils; as for neutrophils lysed by freeze-thaw cycles,
the cytosolic fraction stimulated MIP2, TNF-, and IL-10, whereas the
membranes stimulated TGF- (data not shown).
In the next set of experiments, we used a variety of protease
inhibitors, as well as Abs against human neutrophil elastase and human
cathepsin G, to determine their effects on lysed neutrophil-induced
cytokine production. In Fig. 4, we show
that the serine protease inhibitors PMSF and AEBSF were strong
inhibitors of the proinflammatory response. The serine protease
inhibitors aprotinin and leupeptin were weak inhibitors. Inhibitors of
cysteine proteases (E-64), metalloproteases (bestatin), aspartic
proteases (pepstatin), and calpain had no effect. Anti-human elastase
Ab (50 µg/ml) was a strong inhibitor, but anti-human cathepsin G
(50 µg/ml) was only a weak inhibitor; increasing the concentration of
the latter did not improve the inhibition, and the isotype control
(sheep IgG) had no effect. Neither of these Abs at the concentration
used stimulated cytokine production from control HMDM (data not shown).
These results support the interpretation that neutrophil elastase plays
a major role in the stimulation of macrophage cytokine production.
Next, the production of cytokines from mouse BMDM exposed to
early apoptotic neutrophils (cultured for 3 h after UV
irradiation, trypan blue positivity 4%), late apoptotic neutrophils
(cultured for 24 h after UV irradiation, trypan blue positivity
45%), and lysed neutrophils was assessed. As shown in Fig. 5, late apoptotic cells are similar to
early apoptotic cells in that they induce TGF- secretion and do not
significantly induce MIP2, TNF-, and IL-10.
It was important to determine whether neutrophil elastase could induce
the same pattern of cytokine production as lysed neutrophils.
Therefore, HMDM and mouse BMDM were exposed to purified human
neutrophil elastase and human cathepsin G. As shown in Fig. 6, neutrophil elastase at 0.01 U/ml was a
potent stimulator of mouse macrophage TNF-, MIP2, and IL-10
production; cathepsin G virtually no activity, requiring 5 U/ml to see
a small amount of IL-10 production only. Although not shown, the
effects on HMDMs were identical.
|
shows that early and late apoptotic neutrophils released virtually no
elastase into their medium. Lysed neutrophils, as expected, released a
large amount of elastase, and the proportion remaining in the cell
pellet was significantly lower than that in the pellets from the
apoptotic cells (p < 0.05). Lysed Jurkat T
cells, as expected, were negative for elastase (data not shown).
|
|
Discussion: |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussion:References |
|---|
, IL-10, and either MIP-2 or IL-8, as we
have shown previously (3, 4). This down-regulation results
in large part from secretion of TGF-1, at least part of which is
bioactive (3, 4), and the effects of apoptotic cells can
be mimicked by treatment of macrophages with PtdSer-containing
liposomes or a mAb against a PtdSer receptor (5). Thus,
uptake of apoptotic cells before their lysis not only prevents the
release of potentially toxic or immunogenic intracellular contents but
also induces an anti-inflammatory phenotype in the macrophage. We
also determined that late apoptotic neutrophils, even though becoming
permeable to propidium iodide and trypan blue, behave more like early
apoptotic cells (Fig. 5) because they induced production of TGF- but
did not significantly stimulate TNF-, IL-10, or the chemokine MIP2.
Furthermore, late apoptotic cells released very little elastase into
their culture medium (Fig. 7). These results are in keeping with the
earlier observations of Ren and Savill, who observed that apoptotic
neutrophils beginning to become permeable to trypan blue were not
proinflammatory (14). The response to lysed cells
in the unstimulated macrophages was expected (2) in that
they induced TNF- and chemokine production; however, the levels were
low relative to those seen with a strong proinflammatory stimulus such
as zymosan or LPS (the latter not shown). Lysed cells also consistently
induced IL-10 production, in contrast to apoptotic cells.
When macrophages were stimulated with zymosan, they produced robust
levels of MIP-2 or IL-8, TNF-, and IL-10. Interestingly, lysed
neutrophils were found not to have additive effects in the absence of
serum; rather, they partially (but significantly, p <
0.05) inhibited zymosan-stimulated production of TNF- and IL-10,
although having no effect on the chemokines MIP-2 or IL-8, both of
which are CXC chemokines chemotactic for neutrophils. Lysed neutrophils
also induced significantly less TGF-1 than did early or late
apoptotic cells. Thus, based on these results alone, the presence of
lysed (fully necrotic) cells in vivo would likely cause continuing
influx of neutrophils, particularly following macrophage activation.
The net effect would be prolongation of an inflammatory response.
As expected, lysed neutrophils appeared to be more potent inducers of
macrophage cytokine production in the absence of serum than were lysed
Jurkat T cells, which behaved, for the most part, like apoptotic cells.
Given that granulocytes produce high levels of several different types
of proteases, it seemed reasonable to suggest that the differing
effects of lysed neutrophils compared with lysed lymphocytes were
related to protease release. The serine protease inhibitors PMSF and
AEBSF significantly decreased the proinflammatory effects of lysed
neutrophils on macrophage cytokine production, while leading to an
up-regulation of TGF-1, permitting them to have
anti-inflammatory effects similar to those induced by apoptotic
cells. The strong inhibitory effect of the anti-elastase Ab
supports the notion that neutrophil elastase is a major contributor to
the induction of proinflammatory cytokines and IL-10. This
interpretation is supported by the observations that if lysed
neutrophils were homogenized and separated into membrane and soluble
fractions, the effects of the membranes were indistinguishable from
apoptotic cells, which express phosphatidylserine on their outer
leaflets, and that the proinflammatory signal resided in the soluble
fraction. Furthermore, purified neutrophil elastase directly stimulated
IL-10, TNF-, and chemokine production, and only lysed neutrophils
released elastase into the medium.
How neutrophil elastase directly promotes macrophage proinflammatory
cytokine production is not yet known. It may bind directly to
protease-activated receptors. For example, Ishihara and coworkers
recently demonstrated specific binding of neutrophil elastase to
macrophages; binding was accompanied by enhanced production of
chemokines, which was inhibited by PMSF (15). In vivo, the
proinflammatory actions of the proteases likely result not only from
their actions on macrophages but on other cell types and on
extracellular matrix. Alternatively, or in addition, the proteases may
cleave a critical membrane signal or signals that mediate the
down-regulation of proinflammatory cytokines associated with the uptake
of apoptotic cells. In support of this notion is our observation that
the PtdSer receptor can be cleaved off the cell surface by trypsin
(5); in addition, we have preliminary data to suggest that
neutrophil elastase may cleave it as well (W. Vandivier, V.A.F., and
P.M.H., unpublished data). In fact, the predicted extracellular domain
of the PtdSerR has several potential cleavage sites for neutrophil
elastase, given that the preference for P1 is A>V>T>I
(16). This receptor, when stimulated by apoptotic cells,
phosphatidylserine-containing membranes, or a stimulatory mAb, induces
the release of TGF- and the down-regulation of
proinflammatory cytokines (5). Our studies suggest that
the cellular carcass of a cell progressing to the late stages of
apoptosis can retain anti-inflammatory activity. With regard to the
observations of Ren and Savill that neutrophils that have progressed
from early to late apoptosis (i.e., becoming permeable to trypan blue)
fail to stimulate macrophage cytokine production (14), we
suggest that the anti-inflammatory signal of the exposed
phosphatidylserine on the late apoptotic cell predominates, as the
cells have not released proteases to cleave the PtdSer receptor. In any
event, we suggest that activated, necrotic, or lysed cells can, by
releasing proteases, overwhelm the anti-inflammatory effects of
macrophage PtdSerR interactions with PtdSer-expressing apoptotic cells
or membranous debris, and that prolonged inflammation would be the
predicted end stage of cell death in the absence of clearance by
phagocytes. In vivo, endogenous anti-proteases also contribute to
the complexity of the final response.
One of the interesting observations from this study was that lysed
cells induced release of IL-10, which could be attributed to the effect
of serine proteases, particularly neutrophil elastase. Others have
observed that IL-10 is up-regulated early and concomitantly with
TNF- and chemokines in a variety of inflammatory conditions
(17, 18, 19, 20, 21). Although IL-10 is not believed to affect the
constitutive rate of neutrophil apoptosis, it enhances apoptosis of
neutrophils at inflammatory sites, promotes the survival of
macrophages, and enhances macrophage removal of apoptotic neutrophils
(22, 23, 24, 25, 26). Thus, the protease-mediated release of IL-10 in
inflammatory sites may represent a protective mechanism designed to
promote resolution of inflammation by enhancing neutrophil apoptosis.
Certainly, in its absence, inflammation is more severe in a number of
models (27, 28, 29).
Both TGF- (resulting from stimulation with early or late apoptotic
cells) and IL-10 (resulting from stimulation with lysed cells) have
anti-inflammatory activities, including the down-regulation of
inflammatory mediator production by macrophages (30, 31, 32, 33, 34, 35).
However, in our experiments, down-regulation of chemokines and TNF-
was associated with TGF- production; the pattern of IL-10 secretion
in the absence of serum was similar to that for proinflammatory
cytokines. Both TGF- and IL-10 can be immunosuppressive by exerting
effects on both lymphocytes and APCs (36, 37, 38, 39, 40). However,
TGF- has been shown to inhibit full maturation of dendritic cells,
even in the presence of inflammatory stimuli such as TNF-,
effectively preventing the development of potentially harmful immune
responses from a resolving inflammatory site (41). TGF-
also mediates bystander suppression associated with physiological
self-tolerance in vivo, thereby preventing the activation of
autoreactive lymphocytes (42). These activities may be
critical when apoptotic cells are removed during physiological cell
death or with apoptotic cell uptake associated with resolution of
inflammation.
Exposure to necrotic vs apoptotic cells also has differential effects on maturation of dendritic cells for Ag presentation to lymphocytes. Sauter et al. recently showed that exposure of dendritic cells to necrotic tumor cells or to supernatants derived from these cells enabled them to mature into fully functional APCs (43). They also found differences in cell type in that only necrotic tumor cells, but not necrotic primary cells, could induce this effect. They could not define the active factor; however, released intracellular proteases may be worth evaluating in this system as well.
In summary, we have learned that exposure to apoptotic cells, whether
neutrophils or lymphocytes, inhibited macrophage proinflammatory
cytokine by a mechanism involving TGF- (data presented herein and in
Refs. 4, 5). In contrast, lysed cells, particularly
granulocytes, stimulated production of proinflammatory cytokines and
chemokines, as well as IL-10. Necrotic cells partially down-regulated
zymosan-induced production of TNF- and IL-10, but had no effect on
chemokines. In the presence of a serine protease inhibitor, necrotic
cells behaved like apoptotic cells, inhibiting proinflammatory
cytokines (including chemokines), and increasing release of TGF-1.
These data suggest that the release of serine proteases, particularly
those from neutrophils, can be proinflammatory by directly stimulating
macrophages to produce cytokines. Therefore, lack of removal of
apoptotic cells before lysis will prolong inflammation, increasing the
potential for tissue damage, and thus providing signals to promote an
immune response.
It is important to note that the experiments presented here have been
conducted in the absence of serum to avoid the confounding effects of
complement activation. Giclas and colleagues showed many years ago that
mitochondria can activate the complement cascade, thereby contributing
to the proinflammatory effects of lysed cells (10, 11).
Future work will focus on the effects of serum in our in vitro system
and how it influences the interaction between apoptotic cells and
macrophages; however, preliminary data suggest that exposing
macrophages to either apoptotic neutrophils or Jurkat T cells in the
presence of serum still causes down-regulation of TNF- and chemokine
production, as is seen in the absence of serum; TGF-
production is also up-regulated (V.A.F., unpublished data). These
observations suggest that the anti-inflammatory effects of
apoptotic cells are dominant to any proinflammatory effects of
complement, as apoptotic cells have been shown to activate both the
classical and alternative complement pathways (44).
Interestingly however, in the presence of serum, we found that IL-10
production by macrophages was enhanced by apoptotic cells of either
type, whereas in the absence of serum, its production was inhibited.
Whether IL-10 contributes to the anti-inflammatory effects of
apoptotic cells in our system remains to be determined. Furthermore,
when serum was present, necrotic Jurkat T cells demonstrated
proinflammatory activity in that unstimulated macrophages secreted
TNF- and chemokines. These preliminary results are in keeping with
Giclas’ observations that intracellular organelles can fix complement
(10, 11), particularly because heating serum to 56°C
abolished these effects (V.A.F., unpublished data).
In conclusion, it seems reasonable to hypothesize that apoptotic neutrophils are anti-inflammatory for two reasons: first, they fail to release their serine proteases even when they begin to become leaky (as assessed by uptake of propidium iodide and trypan blue), and because the phosphatidylserine exposed on their surfaces is significantly anti-inflammatory. One can predict that the outcome of inflammation will be determined by the balance between proinflammatory signals generated by the release of granulocyte proteases and anti-inflammatory signals generated by exposure to phosphatidylserine-containing membranes associated with apoptotic cells or membranous cellular debris. The balance between proteases and anti-proteases will also contribute significantly to whether an inflammatory lesion resolves or not. Importantly, the anti-inflammatory potential of apoptotic neutrophils appears to be maintained even through the late stages, providing multiple opportunities for resolution of inflammation.
Note added in proof.
Cocco and Ucker very recently showed that the inhibitory effects of
apoptotic cells on macrophage cytokine production were dominant to the
proinflammatory effects of necrotic cells (45). Jaffray and coworkers
recently showed that pancreatic elastase induces macrophages to produce
TNF- in a NF-
B-dependent manner, supporting the hypothesis of
surface receptors for elastase on macrophages (46).
|
Acknowledgments |
|---|
|
Footnotes |
|---|
2 Address correspondence and reprint requests to Dr. Valerie A. Fadok, National Jewish Medical and Research Center, D509, 1400 Jackson Street, Denver, CO 80206. E-mail address: fadokv{at}njc.org
3 Abbreviations used in this paper: HMDM, human monocyte-derived macrophage(s); MIP2, macrophage-inflammatory protein 2; BMDM, bone marrow-derived macrophage(s); AEBSF, 4-(2-aminoethyl) benzenesulfonylfluoride; TMB, tetramethylbenzidine.
Received for publication March 24, 2000. Accepted for publication March 19, 2001.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussion:References |
|---|
v3/CD36/thrombospondin recognition mechanism and lack of phlogistic response. Am. J. Pathol. 149:911.[Abstract]
, PGE2, and PAF. J. Clin. Invest. 101:890.[Medline]
in macrophages that have ingested apoptotic cells. J. Immunol. 163:6164.2 integrins. J. Immunol. 141:180.
and prostaglandin E2 on tumor necrosis factor and interleukin-10 production in microglia: a regulatory loop controlling microglia pro- and anti-inflammatory activities. J. Neurosci. Res. 56:571.[Medline]
and IL-10 modulate the induction of apoptosis by virulent Mycobacterium tuberculosis in murine macrophages. J. Immunol. 162:6122.: the good, the bad, and the ugly. J. Exp. Med. 180:1587. (TNF-) from human alveolar macrophages and peripheral blood monocytes. Thorax 51:143., IL-4, IL-13, and IL-10. Eur. J. Immunol. 29:1275.[Medline]
1 pretreatment impairs the allostimulatory function of human bone marrow-derived antigen-presenting cells for both naive and primed T cells. Transplant Immunol. 4:186.[Medline]
on bone marrow macrophage Ia expression induced by cytokines. J. Interferon Cytokine Res. 15:485.[Medline]
1 prevents the noncognate maturation of human dendritic Langerhans cells. J. Immunol. 162:4567.-mediated innocent bystander suppression associated with physiological self-tolerance in vivo. Cell. Immunol. 190:51.[Medline]
: role of nuclear factor B proteins. J. Gastointest. Surg. 4:370.
This article has been cited by other articles:
|
|
 |
|
  D. Namgaladze, C. Jennewein, S. Preiss, A. von Knethen, and B. Brune Attenuated suppression of the oxidative burst by cells dying in the presence of oxidized low density lipoprotein J. Lipid Res., November 1, 2009; 50(11): 2173 - 2181. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. N. Waehrens, C. W. Heegaard, G. E. Gilbert, and J. T. Rasmussen Bovine Lactadherin as a Calcium-independent Imaging Agent of Phosphatidylserine Expressed on the Surface of Apoptotic HeLa Cells J. Histochem. Cytochem., October 1, 2009; 57(10): 907 - 914. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H.-N. Li, P. G. Barlow, J. Bylund, A. Mackellar, A. Bjorstad, J. Conlon, P. S. Hiemstra, C. Haslett, M. Gray, A. J. Simpson, et al. Secondary necrosis of apoptotic neutrophils induced by the human cathelicidin LL-37 is not proinflammatory to phagocytosing macrophages J. Leukoc. Biol., October 1, 2009; 86(4): 891 - 902. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Mouded, E. E. Egea, M. J. Brown, S. M. Hanlon, A. M. Houghton, L. W. Tsai, E. P. Ingenito, and S. D. Shapiro Epithelial Cell Apoptosis Causes Acute Lung Injury Masquerading as Emphysema Am. J. Respir. Cell Mol. Biol., October 1, 2009; 41(4): 407 - 414. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. M. Borges, R. W. Vandivier, K. A. McPhillips, J. A. Kench, K. Morimoto, S. D. Groshong, T. R. Richens, B. B. Graham, A. M. Muldrow, L. V. Heule, et al. TNF{alpha} inhibits apoptotic cell clearance in the lung, exacerbating acute inflammation Am J Physiol Lung Cell Mol Physiol, October 1, 2009; 297(4): L586 - L595. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Miles, D. J. Clarke, W. Lu, Z. Sibinska, P. E. Beaumont, D. J. Davidson, T. A. Barr, D. J. Campopiano, and M. Gray Dying and Necrotic Neutrophils Are Anti-Inflammatory Secondary to the Release of {alpha}-Defensins J. Immunol., August 1, 2009; 183(3): 2122 - 2132. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Chopra, J. S. Reuben, and A. C. Sharma Acute Lung Injury:Apoptosis and Signaling Mechanisms Experimental Biology and Medicine, April 1, 2009; 234(4): 361 - 371. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. C. Frasch, K. Z. Berry, R. Fernandez-Boyanapalli, H.-S. Jin, C. Leslie, P. M. Henson, R. C. Murphy, and D. L. Bratton NADPH Oxidase-dependent Generation of Lysophosphatidylserine Enhances Clearance of Activated and Dying Neutrophils via G2A J. Biol. Chem., November 28, 2008; 283(48): 33736 - 33749. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Q. Xiao, C. G. Freire-de-Lima, W. P. Schiemann, D. L. Bratton, R. W. Vandivier, and P. M. Henson Transcriptional and Translational Regulation of TGF-{beta} Production in Response to Apoptotic Cells J. Immunol., September 1, 2008; 181(5): 3575 - 3585. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Afonso, V. M. Borges, H. Cruz, F. L. Ribeiro-Gomes, G. A. DosReis, A. N. Dutra, J. Clarencio, C. I. de Oliveira, A. Barral, M. Barral-Netto, et al. Interactions with apoptotic but not with necrotic neutrophils increase parasite burden in human macrophages infected with Leishmania amazonensis J. Leukoc. Biol., August 1, 2008; 84(2): 389 - 396. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Ashare, A. B. Nymon, K. C. Doerschug, J. M. Morrison, M. M. Monick, and G. W. Hunninghake Insulin-like Growth Factor-1 Improves Survival in Sepsis via Enhanced Hepatic Bacterial Clearance Am. J. Respir. Crit. Care Med., July 15, 2008; 178(2): 149 - 157. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. L. Zaiman, M. Podowski, S. Medicherla, K. Gordy, F. Xu, L. Zhen, L. A. Shimoda, E. Neptune, L. Higgins, A. Murphy, et al. Role of the TGF-{beta}/Alk5 Signaling Pathway in Monocrotaline-induced Pulmonary Hypertension Am. J. Respir. Crit. Care Med., April 15, 2008; 177(8): 896 - 905. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. H. Penn and G. W. Schmid-Schonbein The intestine as source of cytotoxic mediators in shock: free fatty acids and degradation of lipid-binding proteins Am J Physiol Heart Circ Physiol, April 1, 2008; 294(4): H1779 - H1792. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Shibata, K. Nagata, and Y. Kobayashi Cutting Edge: A Critical Role of Nitrogen Oxide in Preventing Inflammation upon Apoptotic Cell Clearance J. Immunol., September 15, 2007; 179(6): 3407 - 3411. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. L. Ribeiro-Gomes, M. C. A. Moniz-de-Souza, M. S. Alexandre-Moreira, W. B. Dias, M. F. Lopes, M. P. Nunes, G. Lungarella, and G. A. DosReis Neutrophils Activate Macrophages for Intracellular Killing of Leishmania major through Recruitment of TLR4 by Neutrophil Elastase J. Immunol., September 15, 2007; 179(6): 3988 - 3994. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Benarafa, G. P. Priebe, and E. Remold-O'Donnell The neutrophil serine protease inhibitor serpinb1 preserves lung defense functions in Pseudomonas aeruginosa infection J. Exp. Med., August 6, 2007; 204(8): 1901 - 1909. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 U. Koedel, U. M. Merbt, C. Schmidt, B. Angele, B. Popp, H. Wagner, H.-W. Pfister, and C. J. Kirschning Acute Brain Injury Triggers MyD88-Dependent, TLR2/4-Independent Inflammatory Responses Am. J. Pathol., July 1, 2007; 171(1): 200 - 213. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Arnold, A. Henry, F. Poron, Y. Baba-Amer, N. van Rooijen, A. Plonquet, R. K. Gherardi, and B. Chazaud Inflammatory monocytes recruited after skeletal muscle injury switch into antiinflammatory macrophages to support myogenesis J. Exp. Med., May 14, 2007; 204(5): 1057 - 1069. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. B. Pagano, M. A. Bartoli, T. L. Ennis, D. Mao, P. M. Simmons, R. W. Thompson, and C. T. N. Pham Critical role of dipeptidyl peptidase I in neutrophil recruitment during the development of experimental abdominal aortic aneurysms PNAS, February 20, 2007; 104(8): 2855 - 2860. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. G. Freire-de-Lima, Y. Q. Xiao, S. J. Gardai, D. L. Bratton, W. P. Schiemann, and P. M. Henson Apoptotic Cells, through Transforming Growth Factor-beta, Coordinately Induce Anti-inflammatory and Suppress Pro-inflammatory Eicosanoid and NO Synthesis in Murine Macrophages J. Biol. Chem., December 15, 2006; 281(50): 38376 - 38384. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. Rytila, M. Plataki, F. Bucchieri, M. Uddin, G. Nong, V. L. Kinnula, and R. Djukanovic Airway neutrophilia in COPD is not associated with increased neutrophil survival Eur. Respir. J., December 1, 2006; 28(6): 1163 - 1169. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. M. Marriott, P. G. Hellewell, S. S. Cross, P. G. Ince, M. K. B. Whyte, and D. H. Dockrell Decreased Alveolar Macrophage Apoptosis Is Associated with Increased Pulmonary Inflammation in a Murine Model of Pneumococcal Pneumonia J. Immunol., November 1, 2006; 177(9): 6480 - 6488. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. van Zandbergen, A. Bollinger, A. Wenzel, S. Kamhawi, R. Voll, M. Klinger, A. Muller, C. Holscher, M. Herrmann, D. Sacks, et al. Leishmania disease development depends on the presence of apoptotic promastigotes in the virulent inoculum PNAS, September 12, 2006; 103(37): 13837 - 13842. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Rydell-Tormanen, L. Uller, and J. S. Erjefalt Direct evidence of secondary necrosis of neutrophils during intense lung inflammation Eur. Respir. J., August 1, 2006; 28(2): 268 - 274. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. W. Vandivier, P. M. Henson, and I. S. Douglas Burying the Dead: The Impact of Failed Apoptotic Cell Removal (Efferocytosis) on Chronic Inflammatory Lung Disease Chest, June 1, 2006; 129(6): 1673 - 1682. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. A. Patel, A. Longacre, K. Hsiao, H. Fan, F. Meng, J. E. Mitchell, J. Rauch, D. S. Ucker, and J. S. Levine Apoptotic Cells, at All Stages of the Death Process, Trigger Characteristic Signaling Events That Are Divergent from and Dominant over Those Triggered by Necrotic Cells: IMPLICATIONS FOR THE DELAYED CLEARANCE MODEL OF AUTOIMMUNITY J. Biol. Chem., February 24, 2006; 281(8): 4663 - 4670. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. C. Di Paolo, S. Tuve, S. Ni, K. E. Hellstrom, I. Hellstrom, and A. Lieber Effect of Adenovirus-Mediated Heat Shock Protein Expression and Oncolysis in Combination with Low-Dose Cyclophosphamide Treatment on Antitumor Immune Responses Cancer Res., January 15, 2006; 66(2): 960 - 969. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Lomas-Neira, C.-S. Chung, M. Perl, S. Gregory, W. Biffl, and A. Ayala Role of alveolar macrophage and migrating neutrophils in hemorrhage-induced priming for ALI subsequent to septic challenge Am J Physiol Lung Cell Mol Physiol, January 1, 2006; 290(1): L51 - L58. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Q. Chen, P. R. Stone, L. M.E. McCowan, and L. W. Chamley Phagocytosis of Necrotic but Not Apoptotic Trophoblasts Induces Endothelial Cell Activation Hypertension, January 1, 2006; 47(1): 116 - 121. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Hanayama and S. Nagata Impaired involution of mammary glands in the absence of milk fat globule EGF factor 8 PNAS, November 15, 2005; 102(46): 16886 - 16891. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Iyoda, K. Nagata, M. Akashi, and Y. Kobayashi Neutrophils Accelerate Macrophage-Mediated Digestion of Apoptotic Cells In Vivo as Well as In Vitro J. Immunol., September 15, 2005; 175(6): 3475 - 3483. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. E. Munoz, U. S. Gaipl, S. Franz, A. Sheriff, R. E. Voll, J. R. Kalden, and M. Herrmann SLE--a disease of clearance deficiency? Rheumatology, September 1, 2005; 44(9): 1101 - 1107. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Maeda, A. Schwarz, K. Kernebeck, N. Gross, Y. Aragane, D. Peritt, and T. Schwarz Intravenous Infusion of Syngeneic Apoptotic Cells by Photopheresis Induces Antigen-Specific Regulatory T Cells J. Immunol., May 15, 2005; 174(10): 5968 - 5976. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Q. Nhan, W. C. Liles, and S. M. Schwartz Role of Caspases in Death and Survival of the Plaque Macrophage Arterioscler Thromb Vasc Biol, May 1, 2005; 25(5): 895 - 903. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Jiang and D. S. Pisetsky The effect of inflammation on the generation of plasma DNA from dead and dying cells in the peritoneum J. Leukoc. Biol., March 1, 2005; 77(3): 296 - 302. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Ran, J. He, X. Huang, M. Soares, D. Scothorn, and P. E. Thorpe Antitumor Effects of a Monoclonal Antibody that Binds Anionic Phospholipids on the Surface of Tumor Blood Vessels in Mice Clin. Cancer Res., February 15, 2005; 11(4): 1551 - 1562. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Devitt, K. G. Parker, C. A. Ogden, C. Oldreive, M. F. Clay, L. A. Melville, C. O. Bellamy, A. Lacy-Hulbert, S. C. Gangloff, S. M. Goyert, et al. Persistence of apoptotic cells without autoimmune disease or inflammation in CD14-/- mice J. Cell Biol., December 20, 2004; 167(6): 1161 - 1170. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Zheng, M. He, M. Long, R. Blomgran, and O. Stendahl Pathogen-Induced Apoptotic Neutrophils Express Heat Shock Proteins and Elicit Activation of Human Macrophages J. Immunol., November 15, 2004; 173(10): 6319 - 6326. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. E. De Larco, B. R. K. Wuertz, and L. T. Furcht The Potential Role of Neutrophils in Promoting the Metastatic Phenotype of Tumors Releasing Interleukin-8 Clin. Cancer Res., August 1, 2004; 10(15): 4895 - 4900. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. H. Ginzberg, P. T. Shannon, T. Suzuki, O. Hong, E. Vachon, T. Moraes, M. T. H. Abreu, V. Cherepanov, X. Wang, C.-W. Chow, et al. Leukocyte elastase induces epithelial apoptosis: role of mitochondial permeability changes and Akt Am J Physiol Gastrointest Liver Physiol, July 1, 2004; 287(1): G286 - G298. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Jiang and D. S. Pisetsky The Effect of Dexamethasone on the Generation of Plasma DNA from Dead and Dying Cells Am. J. Pathol., May 1, 2004; 164(5): 1751 - 1759. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. L. Ribeiro-Gomes, A. C. Otero, N. A. Gomes, M. C. A. Moniz-de-Souza, L. Cysne-Finkelstein, A. C. Arnholdt, V. L. Calich, S. G. Coutinho, M. F. Lopes, and G. A. DosReis Macrophage Interactions with Neutrophils Regulate Leishmania major Infection J. Immunol., April 1, 2004; 172(7): 4454 - 4462. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. E. Young, R. D. Thompson, K. Y. Larbi, M. La, C. E. Roberts, S. D. Shapiro, M. Perretti, and S. Nourshargh Neutrophil Elastase (NE)-Deficient Mice Demonstrate a Nonredundant Role for NE in Neutrophil Migration, Generation of Proinflammatory Mediators, and Phagocytosis in Response to Zymosan Particles In Vivo J. Immunol., April 1, 2004; 172(7): 4493 - 4502. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A P Watt, V Brown, J Courtney, M Kelly, L Garske, J S Elborn, and M Ennis Neutrophil apoptosis, proinflammatory mediators and cell counts in bronchiectasis Thorax, March 1, 2004; 59(3): 231 - 236. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 G. Brouckaert, M. Kalai, D. V. Krysko, X. Saelens, D. Vercammen, `M. Ndlovu, G. Haegeman, K. D'Herde, and P. Vandenabeele Phagocytosis of Necrotic Cells by Macrophages Is Phosphatidylserine Dependent and Does Not Induce Inflammatory Cytokine Production Mol. Biol. Cell, March 1, 2004; 15(3): 1089 - 1100. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Caricchio, L. McPhie, and P. L. Cohen Ultraviolet B Radiation-Induced Cell Death: Critical Role of Ultraviolet Dose in Inflammation and Lupus Autoantigen Redistribution J. Immunol., December 1, 2003; 171(11): 5778 - 5786. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Chen, Y. Wei, G. C. Sharp, and H. Braley-Mullen Mechanisms of Spontaneous Resolution versus Fibrosis in Granulomatous Experimental Autoimmune Thyroiditis J. Immunol., December 1, 2003; 171(11): 6236 - 6243. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H Clark and K Reid The potential of recombinant surfactant protein D therapy to reduce inflammation in neonatal chronic lung disease, cystic fibrosis, and emphysema Arch. Dis. Child., November 1, 2003; 88(11): 981 - 984. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. F. Reidy and J. R. Wright Surfactant protein A enhances apoptotic cell uptake and TGF-{beta}1 release by inflammatory alveolar macrophages Am J Physiol Lung Cell Mol Physiol, October 1, 2003; 285(4): L854 - L861. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 N. Jiang, C. F. Reich III, and D. S. Pisetsky Role of macrophages in the generation of circulating blood nucleosomes from dead and dying cells Blood, September 15, 2003; 102(6): 2243 - 2250. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Kaminski, J. A. Belperio, P. B. Bitterman, L. Chen, S. W. Chensue, A. M.K. Choi, S. Dacic, J. H. Dauber, R. M. du Bois, J. J. Enghild, et al. Idiopathic Pulmonary Fibrosis Am. J. Respir. Cell Mol. Biol., September 1, 2003; 29(3): S1 - 105. [Full Text] [PDF]
|
|
|
|
|
|
C. Odaka, T. Mizuochi, J. Yang, and A. Ding Murine Macrophages Produce Secretory Leukocyte Protease Inhibitor During Clearance of Apoptotic Cells: Implications for Resolution of the Inflammatory Response J. Immunol., August 1, 2003; 171(3): 1507 - 1514. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. K. Nowak, R. A. Lake, A. L. Marzo, B. Scott, W. R. Heath, E. J. Collins, J. A. Frelinger, and B. W. S. Robinson Induction of Tumor Cell Apoptosis In Vivo Increases Tumor Antigen Cross-Presentation, Cross-Priming Rather than Cross-Tolerizing Host Tumor-Specific CD8 T Cells J. Immunol., May 15, 2003; 170(10): 4905 - 4913. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. R. Brown, D. Goldblatt, J. Buddle, L. Morton, and A. J. Thrasher Diminished production of anti-inflammatory mediators during neutrophil apoptosis and macrophage phagocytosis in chronic granulomatous disease (CGD) J. Leukoc. Biol., May 1, 2003; 73(5): 591 - 599. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Knapp, J. C. Leemans, S. Florquin, J. Branger, N. A. Maris, J. Pater, N. van Rooijen, and T. van der Poll Alveolar Macrophages Have a Protective Antiinflammatory Role during Murine Pneumococcal Pneumonia Am. J. Respir. Crit. Care Med., January 15, 2003; 167(2): 171 - 179. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. E. Morelli, A. T. Larregina, W. J. Shufesky, A. F. Zahorchak, A. J. Logar, G. D. Papworth, Z. Wang, S. C. Watkins, L. D. Falo Jr, and A. W. Thomson Internalization of circulating apoptotic cells by splenic marginal zone dendritic cells: dependence on complement receptors and effect on cytokine production Blood, January 15, 2003; 101(2): 611 - 620. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Clark, N. Palaniyar, P. Strong, J. Edmondson, S. Hawgood, and K. B. M. Reid Surfactant Protein D Reduces Alveolar Macrophage Apoptosis In Vivo J. Immunol., September 15, 2002; 169(6): 2892 - 2899. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Bottino, A.N. Balamurugan, S. Bertera, M. Pietropaolo, M. Trucco, and J. D. Piganelli Preservation of Human Islet Cell Functional Mass by Anti-Oxidative Action of a Novel SOD Mimic Compound Diabetes, August 1, 2002; 51(8): 2561 - 2567. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
U. Schonbeck, G. K. Sukhova, N. Gerdes, and P. Libby TH2 Predominant Immune Responses Prevail in Human Abdominal Aortic Aneurysm Am. J. Pathol., August 1, 2002; 161(2): 499 - 506. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Perskvist, M. Long, O. Stendahl, and L. Zheng Mycobacterium tuberculosis Promotes Apoptosis in Human Neutrophils by Activating Caspase-3 and Altering Expression of Bax/Bcl-xL Via an Oxygen-Dependent Pathway J. Immunol., June 15, 2002; 168(12): 6358 - 6365. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Endlich, D. Armstrong, J. Brodsky, M. Novotny, and T. A. Hamilton Distinct Temporal Patterns of Macrophage-Inflammatory Protein-2 and KC Chemokine Gene Expression in Surgical Injury J. Immunol., April 1, 2002; 168(7): 3586 - 3594. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Byrne and D. J. Reen Lipopolysaccharide Induces Rapid Production of IL-10 by Monocytes in the Presence of Apoptotic Neutrophils J. Immunol., February 15, 2002; 168(4): 1968 - 1977. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Somersan, M. Larsson, J. F. Fonteneau, S. Basu, P. Srivastava, and N. Bhardwaj Primary Tumor Tissue Lysates Are Enriched in Heat Shock Proteins and Induce the Maturation of Human Dendritic Cells J. Immunol., November 1, 2001; 167(9): 4844 - 4852. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
