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and IL-1 Sequentially Induce Endothelial ICAM-1 and VCAM-1 Expression in MRL/lpr Lupus-Prone Mice1
British Heart Foundation Cardiovascular Medicine Unit, National Heart and Lung Institute, Imperial College School of Medicine, Hammersmith Hospital, London, United Kingdom
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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and IL-1 for endothelial
activation in MRL/lpr lupus-prone mice. Endothelial
ICAM-1 and VCAM-1 expression increased significantly with disease
evolution in kidney, heart, and brain, as shown by i.v. injected
radiolabeled Ab uptake. Lung endothelial VCAM-1 also increased, while
lung endothelial ICAM-1 did not rise above a high basal level.
Immunoassays showed a significantly raised circulating level of TNF-
by 14 wk, with levels of circulating IL-1 and IL-1ß being
additionally raised by 20 wk. With 14-wk-old MRL/lpr,
anti-TNF- antiserum inhibited expression of ICAM-1 and VCAM-1 by
endothelial cells cultured with sera in vitro, and uptake of
anti-ICAM-1 and anti-VCAM-1 mAb in lung, kidney, brain, and
heart in vivo. In contrast, both anti-TNF- and anti-IL-1
antisera were required for maximal inhibition in vitro and in vivo at
20 wk. These data indicate that TNF- is largely responsible for the
early up-regulation of endothelial ICAM-1 and VCAM-1, but that IL-1
enhances expression in late disease. Our observations provide novel
insights of possible relevance to understanding endothelial activation
in systemic lupus erythematosus, and highlight an approach that can be
extended to dissecting other chronic inflammatory
diseases. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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There has been considerable progress over recent years in understanding
the mechanisms by which leukocytes emigrate from the circulation into
inflamed tissues. Thus, leukocyte recruitment typically involves a
coordinated sequence of adhesion and activation events, consisting of
rolling, firm adhesion, and transmigration into the tissues
(9). ICAM-1 and VCAM-1 are members of the Ig superfamily
and, when expressed by endothelial cells (EC), act respectively as
ligands for leukocyte ß2 (i.e.,
ß2L/LFA-1;
ß2M/Mac-1) and
4 (i.e.,
4ß1/VLA-4;
4ß7/LPAM) integrins
(9). Whereas ICAM-1 is involved in the
ß2 integrin-mediated firm adhesion of
leukocytes that are already rolling on endothelium, VCAM-1 may support
both initial tethering and firm adhesion of cells expressing
4 integrins (e.g., monocytes and lymphocytes)
(10, 11). Expression by EC of ICAM-1 and VCAM-1 is
regulated by cytokines such as TNF and IL-1 (12).
Although the development of inflammatory lesions in both human and
murine lupus is typically associated with leukocyte emigration into
affected tissues, the mechanisms underlying this leukocyte
redistribution are still unknown. However, EC expression of ICAM-1
and/or VCAM-1 has been demonstrated in MRL/lpr tissues
(13, 14, 15, 16), suggesting an increased capacity of endothelium
to support interactions with leukocytes. Furthermore, recent reports
have shown that disease progression in MRL/lpr mice can be
attenuated by anti-ICAM-1 mAb (17), or by
back-crossing with ICAM-1 gene-targeted mice (18, 19).
Although MRL/lpr mice are known to show increased expression
of TNF-, IL-1, and IL-1ß (20, 21, 22, 23, 24, 25, 26, 27), the relative
importance of these cytokines in stimulating EC expression of ICAM-1
and VCAM-1 during the course of the disease has not yet been
determined.
In previous studies, our group has developed the use of i.v. injection
of radiolabeled Abs to quantify lumenal expression of endothelial
adhesion molecules in models of cutaneous inflammation in the pig
(28, 29). The same technique has also been used to study
expression of E- and P-selectins, ICAM-1, and VCAM-1 in models of
inflammation in the rat (30, 31) and mouse
(32, 33, 34). In this work, we report the application of this
approach to dissecting the relative roles of TNF- and IL-1 in the
regulation of endothelial ICAM-1 and VCAM-1 expression during the
development of disease in MRL/lpr mice.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Female BALB/c, MRL/lpr, and MRL/++ mice were purchased from Harlan Olac (Bicester, Oxon, U.K.). MRL/++ have the same genetic background as MRL/lpr mice, but lack the lpr mutation, and do not develop renal disease until the second year of life (35). All mice were kept in the same controlled climatic conditions, in filter-topped microisolator cages, with autoclaved bedding. Irradiated food and drinking water were made freely available. Urine samples were tested for protein using Hema-combistix (Bayer Diagnostics, Basingstoke, U.K.). Blood urea levels were estimated using Azostix (Bayer Diagnostics). All animals were housed and studied according to U.K. Home Office guidelines. Sentinel mice were housed alongside test animals and screened regularly for a standard panel of murine pathogens.
Abs and cell lines
The hybridoma lines for the rat anti-mouse mAb YN-1/1.7.4
(IgG2a, anti-ICAM-1), M/K 2.7 (IgG1, anti-VCAM-1), were
obtained from the American Type Culture Collection (Manassas, VA). The
hybridoma line for the rat anti-mouse anti-CD31 mAb EA3 (IgG2a)
was a kind gift from Dr. Beat Imhof, University of Geneva. Irrelevant
control mAbs (rat IgG1 and rat IgG2a) were raised against DNP and were
a gift from Dr. David Gray (Imperial College School of Medicine,
Hammersmith Hospital, London, U.K.). mAb were purified from tissue
culture supernatants by protein G affinity chromatography (Pharmacia,
Uppsala, Sweden). Sheep anti-mouse TNF- antiserum was a gift
from Dr. Tony Meagher, National Institute for Biological Standards and
Control (Potters Bar, U.K.). Sheep anti-mouse IL-1 and IL-1ß
antisera were gifts from Dr. Roberto Solari (Glaxo-Wellcome
Laboratories, Stevenage, U.K.). Control sheep serum was purchased from
Dakopatts (Glostrup, Denmark). The murine EC line bEnd-3
(36) was kindly supplied by Dr. M. Robinson (Celltech,
Slough, U.K.) and grown in DMEM with 10% FCS, 50 U/ml penicillin (Life
Technologies, Paisley, U.K.), 50 µg/ml streptomycin (Life
Technologies), and 2 mM L-glutamine (ICN Biomedicals, Costa
Mesa, CA) in 5% CO2 at 37°C.
Immunohistochemistry
To localize the uptake in tissues of mAb that had been injected i.v., animals were given 20 µg of either YN-1, M/K 2.7, or control Ab i.v. and 5 min later perfused (as for radiolabeled Ab targeting below) with 2% paraformaldehyde-lysine-periodate (37) under terminal anesthesia. Tissue samples were collected, snap frozen, and subsequently stained to localize the binding of the primary Ab using biotinylated rabbit anti-rat Ig, streptavidin-biotin-HRP, and diaminobenzidine for detection.
Ab radiolabeling
All radioisotopes were purchased from Amersham International (Little Chalfont, U.K.). Abs were labeled with 125I, 111In, or 99mTc, as previously described (34).
Ab targeting
In a preliminary experiment, we established that the distribution of radiolabeled mAb to kidney, brain, lung, and heart 5 min after injection was not influenced by whether the Ab was labeled with 111In, 99mTc, or 125I. Accordingly, in additional experiments, animals received an injection via the tail vein of a mixture of specific and irrelevant control Abs differentially radiolabeled with these three isotopes. Syringes were weighed before and after injection to allow accurate determination of the injected dose (ID). Five minutes after injection, each animal was killed by i.p. injection of an overdose of pentobarbitone sodium (Rhone Merieux, Harlow, Essex, U.K.), and the vasculature was perfused with 20 ml PBS containing 10 U/ml of heparin (Leo Laboratories, Prince Risborough, U.K.), as described (34). Tissue samples were then collected and weighed, and their radioactivity was counted in an automated gamma counter. A standard aliquot of the injected solution was also counted to allow calculation of ID. After corrections for background, spillover between isotopes, and decay, the tissue uptake of each Ab in kidney, lung, heart, and brain was expressed as percentage of ID/g. The specific tissue uptake of each test Ab was then calculated by subtracting the uptake of irrelevant control mAb. In preliminary experiments in normal mice, we determined that the plasma concentration of radiolabeled mAb following i.v. injection was directly inversely related to body weight. Because the body weight of mice increased markedly from 6–20 wk in both BALB/c (18–26 g) and MRL/lpr (22–35 g) mice, in each mouse the specific tissue uptake of test Ab was normalized for body weight to give a concentration factor (CF). Thus, CF = (uptake of test mAb (% ID/g) - uptake of irrelevant control mAb (% ID/g)) x body weight in grams.
A previous study has indicated that the distribution in the mouse of anti-CD31 following i.v. injection can be used to estimate differences between organs in vascularity and endothelial cell surface area (33). Each mouse received 111In-labeled anti-DNP IgG2a control mAb (100 µg) and 100 µg 125I -labeled mAb EA3 anti-CD31 (100 µg), after which the anti-CD31 CF was calculated for lung, heart, kidney, and brain. The relative vascularity (RV) of each of the four organs was then established by dividing the anti-CD31 CF by the anti-CD31 CF for the organ with the lowest anti-CD31 uptake (i.e., brain). On this basis, we calculated an RV of 1, 8.6, 11.2, and 55.9 for brain, kidney, heart, and lung, respectively.
To measure endothelial expression of ICAM-1 and VCAM-1 in vivo, animals received an injection via the tail vein of a mixture (20 µg each) of 99mTc-labeled mAb YN-1/1.7.4, 111In-labeled mAb M/K 2.7, and 125I-labeled control anti-DNP Ab (either IgG1 or IgG2a), 5 min before the end of each experiment. The IgG1 or IgG2a anti-DNP Abs had identical in vivo distributions and were used interchangeably as the negative control, in view of the anti-VCAM-1 (IgG1) and anti-ICAM-1 (IgG2a) being of different isotypes. After calculation of the CF for anti-ICAM-1 and anti-VCAM-1, the values for each organ were divided by the RV for that organ to give a vascularity-corrected CF.
ELISAs for cytokine levels
Blood was aspirated from the left ventricle and allowed to clot
at 4°C overnight. Serum was then separated and frozen at -20°C
before assay of levels of TNF-, IL-1, and IL-1ß, using ELISA
kits purchased from Genzyme (Cambridge, MA).
Stimulation of ICAM-1 and VCAM-1 expression with mouse sera
Mouse sera, which had been collected and stored as for ELISAs,
were incubated at 1:2 in tissue culture medium with bEnd.3 EC for
8 h. After this, cells were analyzed for expression of ICAM-1 and
VCAM-1 by flow cytometry, using FITC-conjugated rabbit anti-rat Ig
(Dako, Carpenteria, CA) for detection. In some wells, EC were incubated
with mouse sera in the presence of sheep anti-mouse TNF-
antiserum, and/or a combination of sheep antisera against mouse IL-1
and IL-1ß (i.e., anti-IL-1).
Inhibition of ICAM-1 and VCAM-1 expression in vivo with polyclonal antisera
In a previous study, we have characterized the ability of
polyclonal rabbit antisera against TNF-, IL-1, and IL-1ß to
inhibit EC expression of ICAM-1 and VCAM-1 in mouse skin following
injection of the respective recombinant cytokine (34). In
the present study, mice received an i.p. injection of anti-mouse
TNF- antiserum (100 µl), a combination of anti-IL-1 (50
µl) and anti-IL-1ß (50 µl) antisera (i.e., anti-IL-1),
anti-TNF- and anti-IL-1, or control sheep serum. To control
for volume, each injection was made up to 200 µl with control sheep
serum. Expression of ICAM-1 and VCAM-1 was measured by the radiolabeled
mAb uptake technique 24 h after the i.p. injection of rabbit
antisera.
Statistics
As the sample sizes in the experiments performed in this project were usually less than 10, a normal distribution was not assumed, and comparisons were therefore made using the Mann-Whitney U test. Differences between groups were described as significant when p < 0.05.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Endothelial expression of ICAM-1 and VCAM-1
Standard immunohistochemical staining of kidney, lung, heart, and
brain showed that in each organ there was increased expression of
ICAM-1 by EC as the MRL/lpr mice aged and also by several
extravascular cell types (not shown). On the other hand, staining of
20-wk-old MRL/lpr mouse tissues with rabbit anti-rat Ig
following an injection i.v. of anti-ICAM-1 or anti-VCAM-1 mAb
showed rat Ig localized specifically on endothelium, as for example in
kidney (Fig. 1
). In view of the
difficulties of quantifying immunohistochemical staining, we then
utilized a radiolabeled Ab-targeting technique to directly measure
changes in endothelial ICAM-1 and VCAM-1 expression over the course of
the disease.
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). Although no significant differences
were observed between the two strains at this age, the
vascularity-corrected uptake of anti-ICAM-1 mAb in lung was
3-fold greater than in kidney, heart, and brain, whereas uptake of
anti-VCAM-1 mAb was 4- to 5-fold greater in kidney compared with
the other organs.
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).
For example, the mean anti-ICAM-1 uptake in heart was 1.8- and
2.6-fold greater at 14 and 20 wk, respectively, compared with uptake at
6 wk, while mean uptake of anti-VCAM-1 was 2.9- and 8.1-fold
greater than baseline at these ages. Although uptake of anti-VCAM-1
was significantly increased in lung at 20 wk, this was not the case for
anti-ICAM-1.
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and IL-1 in MRL/lpr
mice
We next investigated whether the increase in endothelial ICAM-1
and VCAM-1 detectable in vivo was paralleled by increased serum levels
of TNF-, IL-1, and IL-1ß. The circulating cytokine levels
detectable by ELISA in 6-wk-old animals were similar in
MRL/lpr, BALB/c, and MRL/++ mice, and levels in the two
control strains did not change with age (Fig. 4). By 14 wk, the concentration of
immunoreactive TNF- in the serum of the MRL/lpr mice was
148.3 ± 39.2 pg/ml (mean ± SD, n = 4),
which was significantly greater (p < 0.05)
than at 6 wk (37.2 ± 19.3 pg/ml), and there was a further
significant increase by 20 wk (242.3 ± 103 pg/ml). Levels of
IL-1 and IL-1ß were the same at 6 and 14 wk (IL-1, 5.74 ±
1 pg/ml at 6 wk and 5.65 ± 2.3 pg/ml at 14 wk; IL-1ß, 61.9
± 14.6 pg/ml at 6 wk and 75.9 ± 24.9 pg/ml at 14 wk), but had
risen significantly by 20 wk (49.3 ± 20.3 pg/ml and 148 ± 60.8
pg/ml, respectively, both p < 0.05 compared with 14
wk).
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A). In contrast, 14- or
20-wk-old MRL/lpr sera led to a readily detectable
up-regulation of EC expression of both adhesion molecules. In the case
of 14-wk-old serum, up-regulation of ICAM-1 and VCAM-1 expression could
be almost completely inhibited by anti-TNF- antiserum, while
anti-IL-1 had no effect (Fig. 5B). In contrast,
anti-TNF- together with anti-IL-1 led to greater inhibition
of ICAM-1 and VCAM-1 expression than anti-TNF- alone when EC
were incubated with serum from 20-wk-old MRL/lpr mice (Fig. 5C).
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The results of the analysis of cytokines in MRL/lpr
sera suggested that at 14 wk the cytokine that might be responsible for
stimulating increased endothelial expression of ICAM-1 and VCAM-1 at 14
wk was TNF-, but that by 20 wk IL-1 and/or IL-1ß might also
play a role. Experiments were therefore performed to directly analyze
the requirement for these cytokines in vivo, using anti-cytokine
antisera injected i.p. 24 h before injecting radiolabeled Abs
(Fig. 6). No effects of anti-cytokine
antisera were detected in 6-wk MRL/lpr mice, other than
significant inhibition (p < 0.01) of
anti-ICAM-1 mAb uptake by lung endothelium when mice were
pretreated with anti-IL-1. Because inhibition of IL-1 had similar
effects in control 14-wk-old BALB/c mice, it seems likely that the high
endothelial expression of ICAM-1 in mouse lung is maintained normally
by the local generation of IL-1 and/or IL-1ß.
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antiserum. Anti-IL-1 had a weak but significant
(p < 0.05) inhibitory effect on
anti-ICAM-1 mAb uptake in the heart, and had the same marked
inhibitory effect on anti-ICAM-1 mAb uptake in lung as that seen at
6 wk. In contrast, anti-IL-1 had no effect on anti-ICAM-1 mAb
uptake in brain and kidney and failed to inhibit significantly the
uptake of anti-VCAM-1 mAb in any organ. Inhibition of both TNF-
and IL-1 did not lead to any further reduction in ICAM-1 and VCAM-1
expression over that seen with anti-TNF- alone in heart, kidney,
and brain or over that seen in lung with anti-IL-1 alone.
By 20 wk of age, the degree of inhibition of anti-ICAM-1 mAb uptake
by anti-TNF- alone was generally reduced compared with that seen
at 14 wk, such that there was no longer statistically significant
inhibition of anti-ICAM-1 mAb uptake in kidney, brain, or lung.
However, ICAM-1 expression was significantly reduced in all four organs
by inhibiting TNF- and IL-1 together, when compared with animals
that received control antisera. Furthermore, in contrast to 14-wk-old
animals, the combination of anti-TNF- and anti-IL-1 led to a
further significant reduction (p < 0.05) in
ICAM-1 expression in kidney compared with mice that received
anti-TNF- alone. As in 6- and 14-wk-old mice, ICAM-1 expression
in lung was significantly reduced by inhibiting IL-1. In contrast to
anti-ICAM-1 mAb uptake, inhibiting TNF- led to similar
reductions in VCAM-1 expression at 20 wk as at 14 wk, and inhibiting
IL-1 led to no extra effect.
In summary, these data suggest that TNF- has a driving role in
promoting EC ICAM-1 and VCAM-1 expression during the onset of
lupus-like disease in MRL/lpr mice, and that IL-1 and/or
IL-1ß contribute to ICAM-1 but not VCAM-1 expression in late disease
(i.e., at 20 wk).
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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We have been able to demonstrate that there are age-related increases in expression of ICAM-1 and/or VCAM-1 in heart, lung, brain, and kidney of MRL/lpr mice in parallel with the development of disease. These increases are superimposed upon levels of basal expression that differ between organs, but are similar in 6-wk MRL/lpr mice (i.e., before disease onset) to those seen in normal BALB/c mice. Thus, lung has a relatively high basal level of ICAM-1 expression, whereas VCAM-1 is prominent in kidney. A high uptake of anti-ICAM-1 mAb in lung was previously noted in the rat by Panes et al. (31). It is of interest that the lungs of MRL/lpr mice show a particular susceptibility to mononuclear cell infiltration (6), which is reduced by back-crossing MRL/lpr against ICAM-1 gene-targeted mice (18, 19). It is therefore possible that the high expression of ICAM-1 by lung endothelium renders this organ particularly susceptible to the expression of disease. On the other hand, the age-related increase in VCAM-1 expression superimposed upon the relatively high basal expression of VCAM-1 in kidney may provide an alternative adhesion pathway to explain why ICAM-1 deficiency was found not to prevent mononuclear cell infiltration of the kidney in MRL/lpr mice (18, 19).
Increased endothelial expression of ICAM-1 and/or VCAM-1 could clearly
be due to factors acting in a paracrine fashion locally and/or to the
presence of circulating factors able to activate endothelium generally.
Because the uptake of anti-ICAM-1 in both BALB/c and
MRL/lpr lungs was significantly inhibited by a combination
of anti-IL-1 and IL-1ß, it seems likely that the high basal
expression of endothelial ICAM-1 in mouse lung is due to the local
generation of IL-1 and/or IL-1ß, perhaps in response to inhaled
environmental stimuli. Moreover, IL-1-mediated basal stimulation of
lung endothelial ICAM-1 expression may explain why the lung was the
only one of the four organs in which an age-related increase in
anti-ICAM-1 uptake was not detected. In 14-wk MRL/lpr
mice, it is also possible that there may be local production of IL-1
and/or IL-1ß in the heart, because uptake of anti-ICAM-1 mAb was
inhibited, albeit weakly, by anti-IL-1 antisera and there was no
evidence for increased levels of circulating IL-1 or IL-1ß at that
age. On the other hand, both the direct serum cytokine measurements and
the inhibitory effects of anti-TNF- antiserum in vitro strongly
suggest that the generalized increase in ICAM-1 and VCAM-1 expression
at 14 wk is at least in part related to the effects of increased
circulating biologically active TNF-. Using the same argument,
circulating IL-1 and/or IL-1ß appear to contribute to increased
ICAM-1 expression by 20 wk.
Whereas antisera against IL-1 and IL-1ß demonstrated that IL-1
contributes to the generalized ICAM-1 expression in MRL/lpr
mice by 20 wk, we were unable to find any evidence for the in vivo
regulation of VCAM-1 by IL-1, either basally in the lung or during the
progression of disease in MRL/lpr. Although anti-IL-1
antisera did reveal that the IL-1 and/or IL-1ß present in
20-wk-old MRL/lpr sera contributed in vitro to the
up-regulation of VCAM-1 by bEnd-3 cells, differences are known to exist
between cultured EC in their capacity to express VCAM-1 in response to
IL-1 (38). Furthermore, our observations in
MRL/lpr mice support other in vivo work that has indicated
that TNF- is a more important agonist for EC VCAM-1 expression than
IL-1 (29). It is possible that the impaired capacity of
IL-1 to stimulate VCAM-1 expression is related to the presence of an
IL-1-mediated transcriptional repressor in EC (39).
Determining the origin of the increased circulating TNF-, IL-1,
and IL-1ß was beyond the aims of the present study. Previous
investigations have reported raised levels of these and other cytokines
in numerous tissues in MRL/lpr mice (20, 21, 22, 23, 24, 25, 26, 27),
perhaps stimulated by autoantibody or immune-complex deposition
(40). Although our data suggest that TNF- is of primary
importance for the up-regulation of EC ICAM-1 and VCAM-1 expression in
MRL/lpr mice, and that IL-1 contributes to ICAM-1 expression
in late disease, it is also possible that additional mechanisms may be
involved. For example, endothelium might be stimulated by the surface
deposition of activated complement components (41).
Moreover, autoantibodies found in SLE against phospholipids, DNA, and
other endothelial cell Ags have been shown to be capable of directly
inducing EC adhesion molecule expression in vitro (42, 43).
Although our data indicate that there is an age-related increase in
endothelial expression of ICAM-1 and VCAM-1 in MRL/lpr mice,
this should not be seen as implying a generalized increase in leukocyte
adhesion to endothelium and a subsequent nonselective transmigration of
leukocytes into the tissues. In fact, our parallel unpublished
experiments investigating expression of E- and P-selectins in
MRL/lpr mice have shown that these EC adhesion molecules are
not up-regulated with age to the same degree as ICAM-1 and VCAM-1, and
this might be expected to impair neutrophil-EC interactions in most
tissues. In the absence of endothelial selectins, two particular
mechanisms might contribute to the development of the mononuclear cell
tissue infiltrate that characterizes the tissues of MRL/lpr
mice. First, selectin-independent leukocyte-EC contacts are formed
normally during leukocyte passage through capillaries in lung
(44), and probably also in other tissues. Increased
expression of ICAM-1 and VCAM-1 in pulmonary and glomerular capillary
beds might therefore be capable of promoting selectin-independent
leukocyte recruitment into these susceptible organs. Second, the
selective expression of 4 integrins on
mononuclear cells, together with the capacity of
4 integrins to mediate the initial tethering
of circulating leukocytes as well as their stable adhesion to
endothelium (10, 11), may make 4
integrin-VCAM-1 interactions particularly important in this model,
particularly in kidney, which we found to express VCAM-1 relatively
highly. Further studies are therefore required to understand in detail
the functional contributions of increased endothelial ICAM-1 and VCAM-1
expression in MRL/lpr mice and the relative roles of the two
molecules in ongoing leukocyte-EC interactions.
There are a number of clinical immunocytochemical studies showing
increased endothelial expression of ICAM-1 and VCAM-1 in SLE tissues,
including skin (45), skeletal muscle (46),
and kidney (47). Moreover, patients with SLE tend to have
raised circulating levels of soluble VCAM-1 and, to a lesser extent,
soluble ICAM-1 (48, 49). Because there is evidence that
blood levels of TNF- are raised in human SLE (50, 51, 52),
it is possible that similar mechanisms of endothelial cell activation
to those seen in MRL/lpr mice might operate in the human
disease.
Because IL-1 production by several cell types is itself driven by
TNF- (53, 54, 55), it is possible that pretreating the mice
with anti-TNF- for longer than 24 h might have resulted in
a lowering of circulating IL-1 levels and greater inhibition of
adhesion molecule expression than was seen with the protocol we
employed. If so, our study might be interpreted as predicting a
beneficial therapeutic effect of inhibiting TNF- in SLE through the
down-regulation of endothelial activation and adhesion molecule
expression. However previous studies in lpr and NZB/W
lupus-prone mouse models have given conflicting results on the overall
contribution of TNF- to disease progression, concluding that TNF-
protects (56, 57) or accelerates disease (58, 59). With anti-TNF- mAb entering clinical practice for
the treatment of rheumatoid arthritis and inflammatory bowel disease
(60, 61, 62), our data indicate that further research on the
possible therapeutic efficacy of inhibiting TNF- in human SLE would
be worthwhile.
In summary, we have found that the development of lupus-like disease in
MRL/lpr mice is related to systemic TNF--mediated
endothelial activation and ICAM-1 and VCAM-1 expression, and that these
changes are superimposed upon differences between organs in the basal
expression of the two adhesion molecules. Besides suggesting a possible
therapeutic benefit of modulating the endothelial cell response to
cytokines in SLE, our study gives insight into the diversity in
endothelial adhesion molecule expression between organs, which is
likely to impact significantly on the tissue distribution of
multisystem inflammatory diseases. We believe that the approach
described in this study provides an important precedent for dissecting
mechanisms underlying the expression of adhesion molecules and other
endothelial Ags in other models of chronic inflammation.
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Acknowledgments |
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Footnotes |
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2 Address correspondence and reprint requests to Dr. Dorian O. Haskard, British Heart Foundation Cardiovascular Medicine Unit, NHLI, Imperial College School of Medicine, Hammersmith Hospital, London W12 ONN, U.K. E-mail address:
3 Abbreviations used in this paper: SLE, systemic lupus erythematosus; CF, concentration factor; EC, endothelial cell; ID, injected dose; RV, relative vascularity.
Received for publication March 24, 1999. Accepted for publication July 19, 1999.
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 W. Zhao, S. G. Thacker, J. B. Hodgin, H. Zhang, J. H. Wang, J. L. Park, A. Randolph, E. C. Somers, S. Pennathur, M. Kretzler, et al. The Peroxisome Proliferator-Activated Receptor {gamma} Agonist Pioglitazone Improves Cardiometabolic Risk and Renal Inflammation in Murine Lupus J. Immunol., August 15, 2009; 183(4): 2729 - 2740. [Abstract] [Full Text] [PDF]
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 M. U. Norman, W. G. James, and M. J. Hickey Differential roles of ICAM-1 and VCAM-1 in leukocyte-endothelial cell interactions in skin and brain of MRL/faslpr mice J. Leukoc. Biol., July 1, 2008; 84(1): 68 - 76. [Abstract] [Full Text] [PDF]
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A. L. Rops, M. J. van den Hoven, M. A. Bakker, J. F. Lensen, T. J. Wijnhoven, L. P. van den Heuvel, T. H. van Kuppevelt, J. van der Vlag, and J. H. Berden Expression of glomerular heparan sulphate domains in murine and human lupus nephritis Nephrol. Dial. Transplant., July 1, 2007; 22(7): 1891 - 1902. [Abstract] [Full Text] [PDF]
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 H Guo, J C. Leung, L Y. Chan, S L Lui, A W. Tsang, and K N Lai Modulation of intra-pulmonary TGF-b expression by mycophenolate mofetil in lupus prone MRL/lpr mice Lupus, August 1, 2005; 14(8): 583 - 592. [Abstract] [PDF]
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L. Bao, I. Osawe, M. Haas, and R. J. Quigg Signaling through Up-Regulated C3a Receptor Is Key to the Development of Experimental Lupus Nephritis J. Immunol., August 1, 2005; 175(3): 1947 - 1955. [Abstract] [Full Text] [PDF]
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M J Lewis and D D'Cruz Adhesion molecules, mycophenolate mofetil and systemic lupus erythematosus Lupus, March 1, 2005; 14(3_suppl): s17 - s26. [Abstract] [PDF]
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M. Lewis and D. D'Cruz Adhesion molecules, mycophenolate mofetil and systemic lupus erythematosus Lupus, January 1, 2005; 14(1_suppl): s17 - s26. [Abstract] [PDF]
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F Moosig, R Zeuner, C Renk, and J O Schroder IL-1RA in refractory systemic lupus erythematosus Lupus, August 1, 2004; 13(8): 605 - 606. [Abstract] [PDF]
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 C. G. Kevil, M. J. Hicks, X. He, J. Zhang, C. M. Ballantyne, C. Raman, T. R. Schoeb, and D. C. Bullard Loss of LFA-1, but not Mac-1, Protects MRL/MpJ-Faslpr Mice from Autoimmune Disease Am. J. Pathol., August 1, 2004; 165(2): 609 - 616. [Abstract] [Full Text] [PDF]
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 D. Marshall, J. P. Dangerfield, V. K. Bhatia, K. Y. Larbi, S. Nourshargh, and D. O. Haskard MRL/lpr lupus-prone mice show exaggerated ICAM-1-dependent leucocyte adhesion and transendothelial migration in response to TNF-{alpha} Rheumatology, August 1, 2003; 42(8): 929 - 934. [Abstract] [Full Text] [PDF]
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W. G. James, D. C. Bullard, and M. J. Hickey Critical Role of the {alpha}4 Integrin/VCAM-1 Pathway in Cerebral Leukocyte Trafficking in Lupus-Prone MRL/faslpr Mice J. Immunol., January 1, 2003; 170(1): 520 - 527. [Abstract] [Full Text] [PDF]
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M. J. Hickey, D. C. Bullard, A. Issekutz, and W. G. James Leukocyte-Endothelial Cell Interactions Are Enhanced in Dermal Postcapillary Venules of MRL/faslpr (Lupus-Prone) Mice: Roles of P- and E-Selectin J. Immunol., May 1, 2002; 168(9): 4728 - 4736. [Abstract] [Full Text] [PDF]
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 A. Q. Khan, Y. Shen, Z.-Q. Wu, T. A. Wynn, and C. M. Snapper Endogenous Pro- and Anti-Inflammatory Cytokines Differentially Regulate an In Vivo Humoral Response to Streptococcus pneumoniae Infect. Immun., February 1, 2002; 70(2): 749 - 761. [Abstract] [Full Text] [PDF]
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O. A. Harari, D. Marshall, J. F. McHale, S. Ahmed, and D. O. Haskard Limited endothelial E- and P-selectin expression in MRL/lpr lupus-prone mice Rheumatology, August 1, 2001; 40(8): 889 - 895. [Abstract] [Full Text] [PDF]
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 G. P. D. LEMA, H. MAIER, E. NIETO, V. VIELHAUER, B. LUCKOW, F. MAMPASO, and D. SCHLONDORFF Chemokine Expression Precedes Inflammatory Cell Infiltration and Chemokine Receptor and Cytokine Expression during the Initiation of Murine Lupus Nephritis J. Am. Soc. Nephrol., July 1, 2001; 12(7): 1369 - 1382. [Abstract] [Full Text] [PDF]
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R Segal, M Dayan, H Zinger, and E Mozes Suppression of experimental systemic lupus erythematosus (SLE) in mice via TNF inhibition by an anti-TNF{alpha} monoclonal antibody and by pentoxiphylline Lupus, January 1, 2001; 10(1): 23 - 31. [Abstract] [PDF]
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 T. Biedermann, M. Kneilling, R. Mailhammer, K. Maier, C. A. Sander, G. Kollias, S. L. Kunkel, L. Hultner, and M. Rocken Mast Cells Control Neutrophil Recruitment during T Cell-Mediated Delayed-Type Hypersensitivity Reactions through Tumor Necrosis Factor and Macrophage Inflammatory Protein 2 J. Exp. Med., November 20, 2000; 192(10): 1441 - 1452. [Abstract] [Full Text] [PDF]
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