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4ß1 Integrin, Peripheral Node Addressin/L-Selectin, and Lymphocyte Function-Associated Antigen-1 Adhesion Pathways




From the Department of Pathology,*
Stanford
University School of Medicine, Stanford, California; the Pathology and
Laboratory Medicine Service,
Department of
Veterans Affairs, Palo Alto Health Care System, Palo Alto, California;
and the Department of Environmental Medicine,
Kagoshima University Faculty of Medicine, Kagoshima, Japan
| Abstract |
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4 integrin, L-selectin, and
lymphocyte function-associated antigen (LFA)-1. In vivo
studies revealed that antibodies against VCAM-1,
4 integrin, PNAd, L-selectin, or
LFA-1 almost completely blocked lymphocyte migration from blood into
inflamed lacrimal glands. There was no inhibition of migration by
antibodies against mucosal addressin cell adhesion molecule-1 or
4ß7 integrin. These results indicate that
endothelial/lymphocyte adhesion cascades involving
VCAM-1/
4ß1 integrin,
PNAd/L-selectin, and LFA-1 control the migration of lymphocytes
into inflamed lacrimal gland. These adhesion molecules offer potential
therapeutic targets to block the development of lacrimal gland
inflammation and destruction.
| Introduction |
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Nonobese diabetic (NOD) mice are a well-established animal model for human insulin-dependent diabetes mellitus. These mice develop autoimmune-mediated inflammation of pancreatic islets (insulitis) with destruction of the insulin-producing ß cells.9 Along with islet inflammation, NOD mice develop autoimmune-mediated inflammation and destruction of lacrimal and submandibular salivary glands.10 Thus, NOD mice also serve as an animal model for human Sjogrens syndrome, which is an autoimmune disease characterized by lymphocytic inflammation and destruction of salivary glands (sialoadenitis) and lacrimal glands (dacryoadenitis), leading to the development of dry mouth and dry eyes because of insufficient glandular secretions.11 There are several mouse models of Sjogrens syndrome; however, the NOD mouse best mimics the histopathology and the loss of secretory function found in humans with Sjogrens syndrome.12,13
In this study, we investigated the adhesion molecule phenotype of
vascular endothelia and lymphocytes in inflamed lacrimal glands. We
found that vascular cell adhesion molecule-1 (VCAM-1) and peripheral
node addressin (PNAd), but not mucosal addressin cell adhesion
molecule-1 (MAdCAM-1), are expressed by endothelia in inflamed areas of
lacrimal glands. Using adhesion-blocking monoclonal antibodies (mAbs)
in in vivo assays, we show that
VCAM-1/
4ß1 integrin,
PNAd/L-selectin, and lymphocyte function-associated antigen (LFA)-1
adhesion pathways are involved in migration of lymphocytes from blood
into inflamed lacrimal gland.
| Materials and Methods |
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NOD mice were bred in our colony from stock originally obtained from Taconic Farms (Germantown, NY). Prediabetic female and male NOD mice were used for histology studies; prediabetic male NOD mice were used for immunohistochemical and immunofluorescence staining and as hosts for the in vivo migration studies. BALB/c mice and Sprague-Dawley rats were obtained from our animal facility.
Antibodies and Other Reagents
mAbs included anti-
4 [mAb PS/2; American
Type Culture Collection (ATCC), Manassas, VA],
anti-ß7 (Fib504; provided by Dr. D. Andrew,
Cambridge, MA),
anti-
4ß7 heterodimer
(DATK-32; provided by Dr. D. Andrew), anti-
E
(M290; provided by Dr. P. Kilshaw, Cambridge, UK), anti-L-selectin
(MEL-14; ATCC), anti-LFA-1 (FD441.8, ATCC), anti-CD3 (1452C11; BD
PharMingen, San Diego, CA), anti-CD4 (GK1.5, ATCC), anti-CD8 (53-6.72,
ATCC), anti-CD16/CD32 (Fc Block, BD PharMingen), anti-CD19 (1D3, BD
PharMingen), anti-CD45 (M1/9, ATCC), anti-CD45R/B220 (RA3-6B2; provided
by Dr. R. Coffman, Palo Alto, CA), anti-MAdCAM-1 (MECA-367, provided by
Dr. E. Butcher, Stanford, CA), anti-PNAd (MECA-79, provided by Dr. E.
Butcher), anti-VCAM-1 (M/K-2.7, ATCC; and 4B12, provided by Dr. B.
Engelhardt, Bad Nauheim, Germany), anti-ICAM-1 (YN1/1.7, ATCC),
anti-E-selectin (10E9.6, BD PharMingen), and anti-P-selectin (RB40,
ATCC). Negative control mAbs included anti-human CD44 (9B5, provided by
Dr. E. Butcher) and anti-cerebellar granular cell antigen (OZ-42;
provided by Dr. L. Pickford, Palo Alto, CA). For flow cytometry
studies, mAbs were conjugated with fluorescein or allophycocyanin (APC)
as described,14
or purchased from BD PharMingen as
Cy-Chrome conjugates.
Biotinylated anti-rat IgM and peroxidase-streptavidin were purchased from Jackson ImmunoResearch Laboratories (West Grove, PA). Biotinylated anti-rat IgG was obtained from Vector Laboratories (Burlingame, CA), PE-conjugated anti-rat IgG from Biosource International (Camarillo, CA), OCT from Miles (Naperville, IL), and 3,3'-diaminobenzidine tetrahydrochloride from Sigma (St. Louis, MO). Carboxy-fluorescein succinimidyl ester (CFSE) and tetramethylrhodamine isothiocyanate (TRITC) were purchased from Molecular Probes (Eugene, OR).
Histology and Immunohistochemistry
Mice were sacrificed at ages indicated in the text; lacrimal glands and mesenteric LNs (MLNs) were removed and fixed in formalin or snap-frozen in OCT. Hematoxylin and eosin (H&E)-stained sections of the formalin-fixed lacrimal glands were examined by light microscopy. For each gland that showed an inflammatory infiltrate, the areas of the infiltrate and of the gland were measured on three nonconsecutive sections using an image analysis system as described (VAS II; Mideo Systems, Huntington Beach, CA).15 We then calculated the percentage of the gland involved by inflammation (area of inflammation/area of gland x 100).
Frozen sections of lacrimal glands and MLNs were stained using a three-stage immunoperoxidase system. Briefly, the sections were sequentially incubated with rat primary antibody, biotin-conjugated anti-rat IgG or anti-rat IgM, peroxidase-streptavidin, diaminobenzidine/hydrogen peroxide, and methylene blue counterstain. There were two washes with phosphate-buffered saline (PBS) between each step. Slides were examined by light microscopy.15 On slides of lacrimal glands from 2- to 3-, 5-, 10-, 20-, 40-, and 60-week-old male NOD mice, the numbers of vessels expressing PNAd and/or VCAM-1 per mm2 of lacrimal gland area were determined by image analysis as described.15 In addition, if the section showed an inflammatory infiltrate, the percentage of the gland involved by inflammation was determined as described above.
Immunofluorescence Staining and Flow Cytometry
Male NOD mice (10-, 30-, and 60-weeks old) were sacrificed, and then perfused with 10 ml of fluorescence-activated cell sorting (FACS) buffer (PBS with 2% bovine calf serum and 0.05% azide) through the left ventricle to remove intravascular lymphocytes. Lacrimal glands and MLNs were harvested, minced, teased with needles, and filtered over a nylon mesh. For each experiment, lacrimal gland cells were pooled from 6 to 10 mice of the same age. The cell suspensions were collected in FACS buffer and stained using four-color immunofluorescence protocols as described.16 Briefly, suspensions were sequentially incubated with anti-adhesion molecule mAb, PE-anti-rat IgG, 10% normal rat serum, Fc Block, and a mix of APC-anti-CD45, Cy-Chrome-anti-CD3, and fluorescein anti-CD19. There were two washes with FACS buffer after each step, except after incubation with normal rat serum, when Fc Block was added to the suspensions without washing. For negative controls, specific mAbs were replaced by species, isotype- and conjugation-matched irrelevant mAbs. Stained cells were analyzed on a FACScaliber flow cytometer (Becton-Dickinson, San Jose, CA) as described.16 Analysis was performed on 30,000 to 80,000 cells/sample that were within the lymphocyte scatter gate and a CD45+ fluorescence gate. Data are presented as histograms, or as the percentage of cells reacting with a specific mAb minus percentage of cells reacting with the negative control mAb.
In Vivo Lymphocyte Migration Studies
Lymphocytes from spleen, MLNs, and peripheral LNs (PLNs) of 10- to 20-week-old NOD mice were labeled by incubating 2 x 107 cells/ml with 0.8 µg/ml of TRITC in labeling buffer (50% RPMI, 48.5% HBSS without calcium and magnesium, 1.5% bovine calf serum, and 10 mmol/L HEPES) at 37°C for 15 minutes.17 Lymphocytes from rat spleen and MLNs were labeled with CFSE under the same conditions. To remove excess dye, the cells were centrifuged through bovine calf serum, washed, and resuspended in transfer medium (Dulbeccos modified Eagles medium, 1% bovine calf serum, and 10 mmol/L HEPES).
To examine the roles of endothelial adhesion molecules in the migration of lymphocytes from the bloodstream into inflamed lacrimal glands, each host NOD mouse (15- to 20-week-old males) received 500 µg intravenously of anti-endothelial adhesion molecule or negative control mAb, followed 30 minutes later by 5 x 107 TRITC-labeled mouse cells and 100 µg of mAb intravenously. Host mice were sacrificed 2 hours after the cell transfer. Flow cytometry was used to determine the percentage of donor cells of the total cells in host MLN, PLN, PP, and erythrocyte-lysed spleen suspensions, and in blood mononuclear cell preparations. The number of donor cells/mm2 of inflamed lacrimal gland area was determined by confocal microscopy of frozen sections. For each tissue, results for each anti-endothelial adhesion molecule treatment group are expressed as the percentage of migration in the negative control mAb treatment group.
To determine which lymphocyte adhesion molecules are involved in the migration of lymphocytes from the bloodstream into inflamed lacrimal glands, TRITC-labeled mouse cells were treated with 10 µg/ml of anti-lymphocyte adhesion molecule or negative control mAb for 10 minutes on ice. mAb-treated TRITC-labeled mouse cells (5 x 107), 1 x 108 CFSE-labeled rat cells, and 250 µg of mAb were transferred intravenously into each host mouse. The rat cells, which do not bind the antibodies against mouse lymphocyte adhesion molecules, serve as an internal standard to control for differences between host mice in blood flow to tissues and in the efficiency of the injection. An aliquot of the labeled mouse and rat cell mixture was saved to obtain the input mouse/internal control rat cell ratio. Host mice were sacrificed 2 hours after transfer. The ratios of donor mouse/internal control rat cells in host MLN, PLNs, PPs, spleen, and blood were determined by flow cytometry. Donor mouse/internal control rat cell ratios for lacrimal gland were calculated from the numbers of donor mouse and rat cells detected by confocal microscopy of frozen sections. The ratios for all tissues were normalized by the input mouse/internal control rat cell ratio. For each tissue, the results for each anti-lymphocyte adhesion molecule mAb treatment group are presented as percentage migration of control mAb treatment group.
Data Analysis
Numerical data are presented as mean ± SD. Students t-test was used to evaluate differences between treatment groups in the in vivo migration studies. P < 0.05 is considered to be significant.
| Results |
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Our first step was to define the time course of inflammation development in lacrimal glands of the NOD mice from our colony. Lacrimal glands from 1- to 60-week-old prediabetic male and female mice were harvested and fixed in formalin. H&E-stained sections of these glands were examined by light microscopy and the extent of inflammation was quantitated by morphometric analysis.
In our NOD colony, as in other colonies, lacrimal gland inflammation
develops at a younger age in males than in females (Figure 1)
.18,19
There was no
inflammation in lacrimal glands of our 1- to 3-week-old male mice.
However, we saw small aggregates of T and B cells in lacrimal glands
from all of the 5-week-old male NOD mice that we examined
(n = 6 mice). These aggregates were in a
perivascular and periductular distribution, and, on the average,
occupied
5% of the gland area (Figure 1)
. At 10 to 30 weeks of age,
sections of lacrimal glands from most male NOD mice showed several
large foci of perivascular and periductular inflammation. These
infiltrates had poorly segregated B and T cell areas (Figure 2)
. By 40 weeks of age, infiltrates
extended beyond the perivascular/periductular regions to involve the
acinar tissue. In a few of the 40- to 60-week-old male mice, an
extensive lymphocytic infiltrate combined with tissue destruction made
it difficult to identify residual glandular tissue.
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Expression of Endothelial and Lymphocyte Adhesion Molecules in Lacrimal Glands
Our first step in defining the adhesion mechanisms that control
the migration of lymphocytes from the blood into inflamed lacrimal
glands was to determine which endothelial and lymphocyte adhesion
molecules are expressed in inflamed glands. We used immunohistochemical
staining of frozen sections of inflamed lacrimal glands from NOD mice,
and, for comparison, uninflamed lacrimal glands from BALB/c and young
NOD mice, to study endothelial adhesion molecule expression (Figures 3 and 4)
.
Suspension immunofluorescence staining and flow cytometric analysis
were used to define the expression of adhesion molecules on lymphocytes
from NOD-inflamed lacrimal glands (Figure 5)
. We focused on endothelial adhesion
molecules and their lymphocyte ligands that are involved in lymphocyte
migration into tertiary sites of chronic inflammation. These include
VCAM-1, an Ig family member that is expressed by vascular endothelia in
a wide variety of chronically inflamed tissues, and its lymphocyte
ligands
4ß1 and
4ß7
integrin;18,20-23
endothelial PNAd and lymphocyte
L-selectin, which play a major role in lymphocyte migration into PLNs
and a minor role in migration into PPs, and may be involved in
lymphocyte migration to some tertiary lymphoid
tissues;4,5,7,24
endothelial MAdCAM-1 and lymphocyte
4ß7 integrin, which
mediate lymphocyte migration into intestinal secondary lymphoid tissues
such as PPs, and to a few inflamed tissues such as pancreatic islets
and gut;4,5,25,26
endothelial ICAM-1 and lymphocyte LFA-1,
which are involved in lymphocyte migration into most secondary and
tertiary lymphoid tissues;27,28
and endothelial E-selectin
and P-selectin, which mediate lymphocyte migration to some tertiary
lymphoid tissues, such as inflamed skin.29
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18-fold between 2 to 3 and 10 weeks of age (from a mean of
0.4 VCAM-1+ vessels/mm2
of
lacrimal gland area to 7.4 vessels/mm2) and
approximately twofold between 10 and 60 weeks of age (from a mean of
7.4 vessels/mm2
to 13.1
vessels/mm2) (Figure 4)
There was no expression of PNAd in uninflamed lacrimal glands from 2-
to 3-week-old NOD mice (Figure 4)
and any BALB/c mice (data not shown).
PNAd was first seen on vessels in NOD lacrimal glands at the onset of
inflammation (5 weeks of age) (Figure 4)
. The numbers of
PNAd-expressing vessels increased markedly between 5 and 10 weeks of
age, and more gradually thereafter. PNAd expression was confined to
vessels in the areas of inflammation; most of these vessels also
expressed VCAM-1 (Figure 3)
.
There was no expression of MAdCAM-1 by vascular endothelia in the NOD
lacrimal glands, even in the areas of severe inflammation (Figure 3)
(n = 28 mice; three or more nonconsecutive
sections from each mouse). MLNs, used as a positive control tissue in
each staining experiment, showed strong expression of MAdCAM-1 by the
HEV. ICAM-1 and ICAM-2 were expressed by all vessels in the inflamed
foci. We did not find vascular E-selectin or P-selectin in inflamed
areas of any lacrimal gland.
We used four-color immunofluorescence staining and flow cytometric
analysis to define the expression of adhesion molecules by lacrimal
gland T and B lymphocytes. We studied male NOD mice of three different
ages (10, 30, and 60 weeks) to determine whether there are differences
in lymphocyte adhesion molecule expression between the early, middle,
and late stages of the inflammatory process. We found that adhesion
molecule expression by lacrimal gland lymphocytes did not change
appreciably with age (data not shown). Moreover, adhesion molecule
profiles of the lacrimal gland lymphocytes were similar to those of MLN
lymphocytes (Figure 5)
. Specifically, in both tissues, all lymphocytes
expressed LFA-1 and
4 integrin. B cells in
lacrimal gland and MLNs showed moderate expression of
ß7 integrin. T cells showed a bimodal pattern,
with most T cells in both tissues expressing low levels of
ß7, and a smaller population expressing high
levels of ß7. Fewer than 20% of lacrimal gland
and MLN T cells expressed
E integrin (which
can pair with ß7 to form
Eß7) (data not shown).
There was no expression of
E integrin by B
cells in these tissues (data not shown). L-selectin was expressed
by most lymphocytes in both tissues; however, there was a difference in
expression levels between cells in lacrimal gland and MLNs. In MLNs, 30
to 40% of T and B cells expressed high levels of L-selectin. In
contrast, 15 to 20% of lacrimal gland lymphocytes were
L-selectinhi (Figure 5)
.
VCAM-1/
4ß1 Integrin,
PNAd/L-Selectin, and LFA-1 Adhesion Pathways Are Involved in Lymphocyte
Migration to Inflamed Lacrimal Glands
Endothelial VCAM-1 and its lymphocyte ligands
4ß1 and
4ß7 are thought to be
involved in lymphocyte migration into many tertiary lymphoid
tissues.20-23
We found that VCAM-1 is expressed by
vascular endothelia in inflamed foci in NOD lacrimal glands (Figures 3 and 4)
, and that the
4 integrin chain is
expressed by the infiltrating lymphocytes (Figure 5)
. These results
suggest that lymphocytes may migrate into inflamed lacrimal glands
using VCAM-1/
4ß1
and/or VCAM-1/
4ß7
interactions. To evaluate these possibilities, we used short-term
in vivo lymphocyte migration assays to examine the ability
of blocking mAbs against VCAM-1 (mAb 4B12),
4
integrin (PS/2), and
4ß7 integrin
heterodimer (DATK-32) to inhibit the migration of lymphocytes from the
bloodstream into inflamed lacrimal glands of 15- to 20-week-old male
NOD mice. As shown in Figure 6A
,
anti-VCAM-1 mAb blocked most of the lymphocyte migration to inflamed
lacrimal gland without significantly affecting the migration to
secondary lymphoid tissues. In a similar manner,
anti-
4 mAb blocked lymphocyte migration into
inflamed lacrimal glands by
78% (Figure 6B)
. There was no blocking
of lymphocyte migration into lacrimal gland by an antibody (DATK-32)
directed against a combinatorial epitope on the
4ß7 integrin (Figure 6C)
, or by an antibody against MAdCAM-1 (which is also a ligand for
4ß7) (Figure 6D)
. As
expected, anti-
4ß7 and
anti-MAdCAM-1 mAbs inhibited lymphocyte migration into MLNs (not shown)
and PPs (Figure 6, C and D)
.5
These results indicate that
VCAM-1 and
4ß1
integrin are involved in lymphocyte migration from blood into inflamed
lacrimal glands.
|
Treatment of NOD host mice with anti-PNAd mAb blocked 93% of the
lymphocyte migration into inflamed lacrimal glands (Figure 6E)
. In a
similar manner, incubation of donor lymphocytes with a blocking
anti-L-selectin mAb inhibited 82% of the migration to inflamed
lacrimal glands (Figure 6F
and Figure 7
).
As expected, blocking of PNAd or L-selectin almost completely inhibited
lymphocyte migration to PLNs, and partially inhibited lymphocyte
migration into PPs in host mice (Figures 6, E and F)
.5,7,31
These results support the hypothesis that PNAd
and L-selectin target the migration of lymphocytes to inflamed lacrimal
gland.
|
| Discussion |
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Most lymphocytes migrate continuously throughout the body. The major route of recirculation for naive T and B lymphocytes is from blood through secondary lymphoid tissues such as LNs and PPs, into the draining lymphatics and back to blood.2 Antigen stimulation of naive lymphocytes generates memory and effector lymphocytes that migrate effectively from blood into tertiary lymphoid tissues.3 These memory/effector populations show striking tissue selectivity in their abilities to migrate to inflamed sites, such as lung, skin, and gut.23,32,33
Studies of local immune responses, including those in autoimmune diseases such as insulin-dependent diabetes mellitus and thyroiditis, suggest the following migration pathways are involved in the initiation and maintenance of lacrimal gland inflammation.34-36 Dendritic cells capture and process autoantigens in the lacrimal glands, and then migrate through the lymphatics to the regional LNs. The initial T cell priming is thought to occur in these regional LNs where the dendritic cells present autoantigen to recirculating naive T cells.3 This generates T memory/effector cells that migrate effectively from the blood into the lacrimal gland, where they meet their cognate antigens.3,23,32,33,37 The local inflammatory response is initiated, with production of activating and chemoattractant molecules including cytokines and chemokines, and up-regulation of endothelial adhesion molecules that support the migration of cells from the bloodstream into the tissue. The subsequent influx of antigen-specific and effector lymphocytes and other leukocytes into the lacrimal glands causes tissue destruction and clinical symptoms such as dry eyes.11
In this study, we used tissue-section immunohistochemistry and
suspension immunofluorescence staining to determine the patterns of
expression of endothelial and lymphocyte adhesion molecules in lacrimal
glands from NOD mice. The physiological importance of these molecules
in lymphocyte migration from blood into inflamed lacrimal glands was
determined using short-term in vivo migration studies. Our
results indicate that
VCAM-1/
4ß1,
PNAd/L-selectin, and LFA-1 adhesion pathways play important roles in
this migration.
Endothelial/Lymphocyte Adhesion Pathways Involved in Lymphocyte Migration into Inflamed Lacrimal Gland
VCAM-1 and
4ß1 Integrin
Endothelial VCAM-1 and lymphocyte
4ß1 integrin mediate
the migration of lymphocytes to tertiary lymphoid tissues, including
lung, brain, and skin.21-23
Although
4ß7 can also bind to
VCAM-1,
4ß1 is thought
to be the major physiological ligand for VCAM-1.20
In NOD lacrimal gland, we found that: 1) VCAM-1-expressing vessels are
located mainly in areas of inflammation (Figure 3)
; 2) the numbers of
VCAM-1+ vessels increase with increasing
inflammation (Figure 4)
; 3) essentially all T and B cells in inflamed
lacrimal gland express the
4 integrin chain
(Figure 5)
; and 4) antibodies against VCAM-1 and
4 integrin, but not against the
4ß7 heterodimer, block
lymphocyte migration into inflamed lacrimal gland (we do not have an
antibody that reacts specifically with ß1 chain
or the
4ß1
heterodimer) (Figure 6; A, B, and C
). These results indicate that
4ß1 and VCAM-1
participate in lymphocyte migration to inflamed lacrimal glands.
MAdCAM-1 and
4ß7 Integrin
Endothelial MAdCAM-1 and its lymphocyte ligand
4ß7 integrin direct
the migration of predominantly naive lymphocytes to intestinal
secondary lymphoid tissues (PPs and MLNs).5,25,38
MAdCAM-1
is also expressed by venules in lamina propria in normal and inflamed
intestine, and by HEV in inflamed islets in NOD mice, and is thought to
be involved in lymphocyte recruitment to these
sites.4,25,26,30,39,40
MAdCAM-1 does not serve as an
adhesion molecule in all mucosal lymphoid tissues, however. For
example, HEV in several mucosal sitesincluding tonsil,
bronchus-associated lymphoid tissues (BALT) (Xu, Butcher, and Michie,
unpublished observation), nasal-associated lymphoid tissues, inflamed
oral mucosa, and inflamed conjunctivafail to express functionally
significant levels of MAdCAM-1.40-42
Although lacrimal glands are mucosal tissues, we did not find
expression of MAdCAM-1 in normal or inflamed glands (Figure 3)
.
Moreover, antibodies against the
4ß7 integrin and
MAdCAM-1 did not block lymphocyte migration into inflamed lacrimal
gland (Figure 6, C and D)
. Thus,
MAdCAM-1/
4ß7
interactions do not direct the migration of lymphocytes from the
bloodstream into inflamed lacrimal glands.
PNAd and L-Selectin
PNAd, which was originally identified on PLN HEV by reactivity with mAb MECA-79, consists of carbohydrate epitopes that bind L-selectin.31,43 PNAd/L-selectin interactions are important in the migration of naive lymphocytes to PLNs, and play a role in lymphocyte migration to PPs.5,7,31,44 MECA-79 reactive venules are also found in some sites of chronic inflammation, and may be involved in lymphocyte migration to these sites.4,24,30
In the current study, we did not see vascular expression of PNAd in
uninflamed lacrimal glands from BALB/c or very young NOD mice. However,
in NOD lacrimal glands, PNAd expression was seen at the onset of
inflammation. Moreover, the numbers of PNAd+
vessels increased along with the inflammation (Figure 4)
. Our in
vivo assays show that inhibition of either PNAd or L-selectin
blocks >80% of lymphocyte migration to inflamed lacrimal glands
(Figure 6, E and F)
. Our suspension staining and flow cytometry studies
indicate that L-selectin is expressed by almost all T and B cells in
inflamed lacrimal gland (Figure 5)
. However, most of the lymphocytes
express low to medium levels of L-selectin. Lymphocyte activation is
known to induce shedding of surface L-selectin.45
Thus,
blood-borne lymphocytes may have used L-selectin to interact with the
lacrimal gland endothelium, and then down-regulated the receptor after
migration into the gland parenchyma. Alternatively, inflamed lacrimal
glands may selectively recruit or retain lymphocyte subsets with low to
medium levels of L-selectin.
LFA-1
LFA-1 is involved in lymphocyte migration to many secondary and
tertiary lymphoid tissues.27,28
In situ
microscopy studies show that LFA-1 is essential for
activation-dependent sticking (step 3) of lymphocytes to HEV in LNs and
PPs.5,7
Members of the ICAM family of adhesion molecules
are thought to serve as endothelial ligands for LFA-1. Using short-term
in vivo assays, we found that treatment of lymphocytes with
an antibody against LFA-1 blocks almost all migration of lymphocytes
from blood into inflamed lacrimal glands (Figure 6G)
.
Multistep Cascades for Lymphocyte Migration into Inflamed Lacrimal Gland
An important feature in the regulation of lymphocyte recirculation is the ability of lymphocytes to recognize and bind to the surface of blood vessel endothelial cells before migrating through the vessel wall into surrounding tissue. Recent studies have shown that adhesion interactions of vascular endothelia with lymphocytes under flow or shear consist of multistep cascades with at least four steps: 1) an initial transient tethering and rolling: most lymphocyte adhesion molecules, such as L-selectin, that are involved in rolling are found on the tips of the lymphocytes microvilli, where they can easily contact the endothelium; 2) if the lymphocytes encounter appropriate activating factors such as chemokines in the local environment, rolling may be followed by a lymphocyte activation step mediated primarily through G protein-linked chemoattractant receptors, which then leads to; 3) firm adhesion or sticking mediated by activated integrins interacting with endothelial immunoglobulin family members, that may be followed by; 4) lymphocyte diapedesis through the endothelium into tissue, probably also directed by chemokines.5-8
Our studies, in conjunction with known roles for adhesion molecules in
the cascades in LNs and PPs, suggest that lymphocyte migration from
blood into inflamed lacrimal glands uses a multistep cascade as
follows: lymphocytes tether and roll (step 1) using
VCAM-1/
4ß1 and
PNAd/L-selectin; after activation (step 2) by as yet undefined
cytokines or chemokines, there is firm adhesion (step 3) mediated by
lymphocyte LFA-1 binding to endothelial ICAMs, and lymphocyte
4ß1 binding to
endothelial VCAM-1; diapedesis (step 4) through the endothelium into
lacrimal gland parenchyma is mediated by unknown adhesion molecules,
and by activating factors that may include the chemokines RANTES and
IP-10.46
| Summary |
|---|
|
|
|---|
4ß1 integrin,
PNAd/L-selectin, and LFA-1. Inhibition of these lymphocyte and
endothelial adhesion molecules may permit selective modulation of
lacrimal gland inflammation, and thus prevention of lacrimal gland
destruction, in Sjogrens syndrome.
| Footnotes |
|---|
Supported by the National Institutes of Health (AI 47574) (to S. A. M.) and by a Merit Review Award from the Department of Veterans Affairs (to S. A. M.).
Present address of A. Mikulowska-Mennis: Arcturus Engineering, Inc., 400 Logue Ave., Mountain View, CA, 94043-4019.
Accepted for publication April 27, 2001.
| References |
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4ß7 and LFA-1 in lymphocyte homing to Peyers patch-HEV in situ: the multistep model confirmed and refined. Immunity 1995, 3:99-108[Medline]
4ß1 (VLA-4) and
4ß7 on the human B cell line JY. J Biol Chem 1992, 267:8366-8370
4-integrin but not
4ß7-integrin. J Clin Invest 1998, 102:2096-2105[Medline]
4-integrins and vascular cell adhesion molecule-1. Am J Physiol 1997, 272:L219-L229
4ß7-integrin. Diabetes 1997, 46:583-588[Abstract]
4ß7 integrin mediates lymphocyte binding to the mucosal vascular addressin MAdCAM-1. Cell 1993, 74:185-195[Medline]
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R. Ou, M. Zhang, L. Huang, R. A. Flavell, P. A. Koni, and D. Moskophidis Regulation of Immune Response and Inflammatory Reactions against Viral Infection by VCAM-1 J. Virol., March 15, 2008; 82(6): 2952 - 2965. [Abstract] [Full Text] [PDF] |
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M. Ramos-Casals and P. Brito-Zeron Emerging biological therapies in primary Sjogren's syndrome Rheumatology, September 1, 2007; 46(9): 1389 - 1396. [Abstract] [Full Text] [PDF] |
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J. Rivera-Nieves, T. L. Burcin, T. S. Olson, M. A. Morris, M. McDuffie, F. Cominelli, and K. Ley Critical role of endothelial P-selectin glycoprotein ligand 1 in chronic murine ileitis J. Exp. Med., April 17, 2006; 203(4): 907 - 917. [Abstract] [Full Text] [PDF] |
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J. J. Garcia-Vallejo, W. van Dijk, I. van Die, and S. I. Gringhuis Tumor Necrosis Factor-{alpha} Up-regulates the Expression of {beta}1,4-Galactosyltransferase I in Primary Human Endothelial Cells by mRNA Stabilization J. Biol. Chem., April 1, 2005; 280(13): 12676 - 12682. [Abstract] [Full Text] [PDF] |
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S. D. Rosen, D. Tsay, M. S. Singer, S. Hemmerich, and W. M. Abraham Therapeutic Targeting of Endothelial Ligands for L-selectin (PNAd) in a Sheep Model of Asthma Am. J. Pathol., March 1, 2005; 166(3): 935 - 944. [Abstract] [Full Text] [PDF] |
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M. Huang, K. Matthews, T. J. Siahaan, and C. G. Kevil {alpha}L-Integrin I domain cyclic peptide antagonist selectively inhibits T cell adhesion to pancreatic islet microvascular endothelium Am J Physiol Gastrointest Liver Physiol, January 1, 2005; 288(1): G67 - G73. [Abstract] [Full Text] [PDF] |
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A. Bistrup, D. Tsay, P. Shenoy, M. S. Singer, N. Bangia, S. A. Luther, J. G. Cyster, N. H. Ruddle, and S. D. Rosen Detection of a Sulfotransferase (HEC-GlcNAc6ST) in High Endothelial Venules of Lymph Nodes and in High Endothelial Venule-Like Vessels within Ectopic Lymphoid Aggregates: Relationship to the MECA-79 Epitope Am. J. Pathol., May 1, 2004; 164(5): 1635 - 1644. [Abstract] [Full Text] [PDF] |
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B. Xu, N. Wagner, L. N. Pham, V. Magno, Z. Shan, E. C. Butcher, and S. A. Michie Lymphocyte Homing to Bronchus-associated Lymphoid Tissue (BALT) Is Mediated by L-selectin/PNAd, {alpha}4{beta}1 Integrin/VCAM-1, and LFA-1 Adhesion Pathways J. Exp. Med., May 19, 2003; 197(10): 1255 - 1267. [Abstract] [Full Text] [PDF] |
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T. Hirata, B. C. Furie, and B. Furie P-, E-, and L-Selectin Mediate Migration of Activated CD8+ T Lymphocytes into Inflamed Skin J. Immunol., October 15, 2002; 169(8): 4307 - 4313. [Abstract] [Full Text] [PDF] |
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R. H. Friedline, C. P. Wong, D. A. Steeber, T. F. Tedder, and R. Tisch L-Selectin Is Not Required for T Cell-Mediated Autoimmune Diabetes J. Immunol., March 15, 2002; 168(6): 2659 - 2666. [Abstract] [Full Text] [PDF] |
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