Extract
Note: Please read the complete
full text with Figures and Tables at
Introduction
Inflammation is a self-protective process under
physiological conditions, but an extreme inflammatory reaction
can result in the immune damage of organisms and cause
pathological situations. A hallmark of inflammation is the
adhesion of leucocytes to vascular endothelial cells
(VEC)[1]. The binding of adhesion molecules expressed on leucocytes
and VEC to their ligands is the critical molecular mechanism
for this reaction[2,3].
Selectin is one of the cell adhesion molecule families that
mediate the adhesion of leucocytes to VEC, leucocytes to
leucocytes, and leucocytes to platelets during inflammation.
There are 3 kinds of selectins: P-, L-, and E-selectin, which
function in different phases of cell
adhesion[3]. P-selectin, a transmembrane glycoprotein expressed on the surface of
activated platelets and VEC, acts as a receptor to mediate the
initial adhesion of leucocytes[4]. In
vivo, P-selectin antibodies can block leucocyte rolling and adhesion in venules and
accumulating in tissues, and P-selectin-deficient mice exhibit
severely diminished leucocyte rolling and delayed
recruitment of leucocytes in various inflammatory tissues. As a
result, the antagonists that block or interfere with the role of
P-selectin may affect the inflammatory
process[5_7].
In the past decade, several P-selectin antagonists have
been developed, including mAb, sLex,
sLea, heparin, as well as its mimetics. Although these antagonists have been
shown to be effective in inhibiting P-selectin-mediated
leucocyte adhesion and inflammation, they also exhibit various
drawbacks, such as narrow cross-reactivity, weak affinity,
and a short circulating half-life[8,9]. Currently, much work
has been focused on finding better inhibitors to prevent
abnormal leucocyte emigration[10,11]. Polysaccharides of
Ginkgo biloba leaves (PGBL) are active components with
multiple pharmacological functions, such as oxyradical and
hydroxy radical clearance effects, anti-aging properties,
antitumor activities, and immunomodulatory
effects[12_14]. Rough PGBL have been reported to have anti-inflammatory
effects, yet the mechanism remains
unclear[15]. In this paper, we investigated the role and mechanism of purified PGBL
(p-PGBL) on anti-inflammation and found that p-PGBL can
inhibit P-selectin-mediated leucocyte adhesion and
inflammation.
Materials and methods
Animals and cells BALB/c mice (5_6 weeks old) were
purchased from the Experimental Research Center of
Medical Animals in Changchun (China). Chinese hamster ovary
(CHO) cells and HL-60 cells, a human leukaemia cell line,
were bought from the Institute of Biochemistry and Cell
Biology, Shanghai Institutes for Biological Sciences,
Chinese Academy of Sciences (Shanghai, China). The CHO
cells were cultured in Iscove's Modified Dulbecco's
Medium (IMDM) and the HL-60 cells were cultured in
RPMI-1640 medium at 37 °C in the presence of 5%
CO2, and they were all supplemented with 10% inactivated fetal calf serum
(FCS). Human neutrophils were isolated according to the
Ficoll density gradient centrifugation method and maintained
in RPMI-1640 medium without FCS. Human umbilical vein
endothelial cells (HUVEC) were isolated by collagenase
treatment as described
previously[16,17]. HUVEC were passaged
by mild trypsinization (0.25% trypsin/0.02 EDTA) and
cultured to confluence in 1% gelatin-coated 35 mm culture
dishes. Before use in the adhesion assays, HUVEC were
stimulated with 1 U/mL human thrombin for 10 min to obtain
maximal levels of P-selectin
expression[18].
Proteins and antibodies Recombinant human
P-selectin/Fc chimera protein (P-Fc) and blocking mAb to P-selectin
(9E1) were obtained from R&D Systems (Minneapolis,
Minnesota, USA). A non-blocking mAb to P-selectin
(AC1.2) was purchased from BD PharMingen (Franklin Lakes, New
Jersey, USA). Goat antihuman fluorescein-isothiocyanate
(FITC)-labeled immunoglobulin G (IgG) and goat antimouse
IgG were purchased from Jackson Immuno-Research
Laboratories (West Grove, Pennsylvania, USA). Collagenase and
human thrombin were purchased from Sigma_Aldrich (St
Louis, Missouri, USA).
Other reagents Sephadex G-75 was obtained from
Pharmacia (North Peapack, New Jersey, USA).
Thioglycollate broth was obtained from Sigma_Aldrich (USA). All other
chemicals were of analytical grade.
Isolation and purification of PGBL Ginkgo
biloba leaves were collected from Dandong, Liaoning Province. The PGBL
were extracted from fresh Ginkgo biloba leaves according
to routine methods[19]. To achieve p-PGBL, the PGBL were
frozen and thawed repeatedly, ultrafiltrated by 30 000
ultrafiltration membranes, and freeze-dried. The powder was
fractionalized by gel chromatography on a Sephadex G-75
column (4 cm×80 cm) and collected by an automatic fraction
collector (BS-100A,Shanghai Huxi Analysis Instrument
Factory Co. LTD, Shanghai, China). Then the fraction with the
highest peak on the distribution curve was dialyzed,
concentrated, and freeze-dried to obtain p-PGBL. p-PGBL
purity was measured by gel chromatography on a Sephadex
G-75 column (1.5 cm×95 cm) and HPLC, respectively. All gel
chromatography was monitored with the phenol-sulfuric acid
method. The molecular weight of p-PGBL was calculated
according to the calibration curve obtained by using
various standard dextrans. Nucleotides and proteins in p-PGBL
were inspected by a UV spectrum assay. Optical rotation
was measured with a WZZ-T1 polarimeter (Shanghai
Physical Optics Instrument, Shanghai, China). The
polysaccharide component was determined by gas chromatography
(GC)[20].
Preparation of CHO cells expressing human
P-selectin Full-length human P-selectin cDNA, subcloned in a pcDNA
3.1 (_) vector, was a kind gift from Dr Spertini O (Centre
Hospitalier Universitaire Vaudois, Lausanne Switzerland).
The cDNA was 2500 base pairs in length, and were inserted
in pcDNA3.1 (_) plasmids at the EcoRV and
NotI cloning sites. Then the plasmids were transfected by an
electroporation apparatus (160 V; Gene Pulser X cellTM,
BIO-RAD, Hercules, California, USA) into CHO cells, which do
not express P-selectin. The transfected CHO cells were
selected with G418, and the monoclones of the cells that
steadily expressed human P-selectin were selected for the
cell adhesion experiment under flow
conditions[21].
Ear edema in mice induced by xylene The mice (18~22 g)
were randomly divided into 5 individual groups with 8 (sex
ratio 1:1) in each group. Each group of mice was
intraperitoneally injected with 12.5, 25, and 50 mg/kg p-PGBL or 2 mg/kg dexamethasone (negative control) or 2 mg/kg sterile
saline (positive control), respectively, and the injection
interval was 12 h. Thirty minutes after the third injection, a
topical edema was induced in each mouse by applying 0.05
mL xylene to both sides of the right ear of each mouse. The
mice were killed by luxation method 0.5
h after inflammation was developed, and an 8 mm diameter round slice was cut
from the same sites of both ears by using a perforator. The
slices were then weighed. The edema level was assessed in
terms of the increase in the weight of the right ear piece over
that of the left ear. The mean of the difference between the
right and left ears was determined for each group. The
inhibition percentages were calculated by comparison with the
positive control group that only received the xylene application
but none of the treatments[15,22].
Thioglycollate-induced peritoneal
inflammation In each experimental test, the male mice were randomly separated
into 6 individual groups and intraperitoneally injected with 2
mL of 3% thioglycollate broth or sterile pyrogen-free saline.
Five minutes later, the mice were intravenously injected with
0.2 mL of either sterile pyrogen-free saline or different
concentration of p-PGBL. The mice were killed after 3 h, and
their peritoneal cavities were lavaged with 2 mL
phosphate-buffered saline (PBS)[18]. One part of the total peritoneal
cells was double-blindly counted with a hemocytometer, while
the other part of the cells was fixed and stained with
Wright_Giemsa. Neutrophils were counted under a microscope
(15_20 counts/slide for a total of 800 cells) and neutrophils/mL
were calculated.
Flow cytometric assays For the cell surface P-selectin
binding assay, P-Fc (0.3 µg) was pre-incubated with PBS
supplemented with 1 mmol CaCl2 and 1 mmol
MgCl2, mAb 9E1, or different concentration of p-PGBL at 37 °C for 30 min.
Then 100 µL HL-60 cells or human neutrophils
(5×109/L) were added and the mixture was incubated at 4 °C for 30 min. After
incubation, the cells were washed once, resuspended in 100
µL RPMI-1640 medium containing FITC-labeled goat
antihuman IgG (2 mg/L), and incubated at 4 °C for another 30
min. The cells were then washed twice, and 10 000 cells were
counted for flow cytometric analysis with a FACScan (Becton
Dickinson, Franklin Lakes, New Jersey,
USA)[18].
Flow chamber assays CHO cells, CHO cells expressing
human P-selectin (CHO-P), and HUVEC
(4×108/L) were seeded in 35 mm culture dishes, respectively, to allow cell
monolayers to form. Then mAb 9E1 and different
concentration of p-PGBL were added, separately. After the cells were
incubated in a CO2 incubator for 30 min, the dishes were
assembled in a parallel-plate flow chamber (GlycoTech,
Rochville, MD, USA) and mounted on the objective table of
an inverted microscope (Olympus Optical, Tokyo, Japan).
After washing the flow chamber with Dulbecco's PBS
containing 0.1% bovine serum albumin for 2 min,
2×109/L human neutrophils were perfused through the chamber at a
appropriate flow rate to obtain wall shear stress of 0.12 Pa at 22 °C
by using a syringe pump (Cole_Parmer Instrument Company,
Vernon Hills, Illinois, USA), thereby mimicking the fluid
mechanical environment of the microcirculation and
postcapillary venules. After the appearance of the
neutrophils, the field was randomly selected and recorded
via the camera (Panasonic, Yokohama, Japan) connected to
the inverted microscope. The video was later transferred to
a computer. Each sample had 3 dishes, and each dish was
measured for 3 min. The mean value was calculated from 3
trials. The number of neutrophils attached to CHO cells,
CHO-P cells, and HUVEC per unit time and area was
manually determined by reviewing the videos. The relative
adhesion rate of the different concentration of p-PGBL was
calculated[18,23].
Statistical analysis Data were expressed as the
mean±SEM. The statistical significance of differences
between means was determined by ANOVA. If the means were
shown to be significantly different, multiple comparisons by
pairs were performed with the Tukey test. Probability values
of P< 0.05 or P<0.01 were selected to be statistically significant.
Results
PGBL extraction and purification Water-soluble
brown_white powder was isolated from Ginkgo
biloba leaves and the yield rate was 8.6%. The white powder (p-PGBL) was
obtained by deproteinization, ultrafiltration and gel
chromatography on a Sephadex G-75 column and freeze-dried. The
purity of p-PGBL was confirmed by gel chromatogram on a
Sephadex G-75 column and HPLC, and showed that the
symmetrical peak that appeared at 16.54 min was consistent with
the PGBL peak that had the highest polysaccharide content
(Figure 1). An absorption spectrum at 260_280 nm was not
detected by the UV spectrum assay, indicating that neither
nucleotides nor proteins were presented in p-PGBL.
According to the standard curve, the relative molecular weight
of p-PGBL was ~10 kDa, and the purity was 98.8%. Optical
rotation was (a)20n=+43. Analyzed by GC, the
monosaccharide composition was Gal, Man, Glu, Ara, Rha and
galacturonic, and the molar ratio was 6:2.4:1.7:4.6:6.8:1.
p-PGBL inhibits acute inflammation in mice
To investigate the anti-inflammatory effect of p-PGBL, the acute
inflammation model of ear edema in mice induced by xylene
was first used in our experiment. As shown in Figure 2A, the
ear edema in mice could be inhibited by p-PGBL at
concentrations of 12.5, 25, and 50 mg/kg. Compared with the
positive control mice (the sterile saline-injected mice), the
inhibition rates of p-PGBL were 36.8%, 56.09%, and 64.27%,
respectively. The inhibition effect of the p-PGBL was dose
dependent. Then we further investigated the
anti-inflammatory effect of p-PGBL by using the well-established acute
peritonitis model in mice. The results showed that the
thioglycollate injection greatly increased the neutrophils in
the peritoneal cavity. Compared with the positive control
mice (the thioglycollate-injected mice), 5 and 25 mg/kg
p-PGBL could inhibit thioglycollate-induced neutrophil
transmigration with an inhibition rate of 46.43% and 78.11%,
respectively, and 50 mg/kg p-PGBL could entirely block
thioglycollate-induced neutrophil transmigration (Figure 2B).
The data suggest that p-PGBL has obvious inhibitory
effects on acute inflammation, and p-PGBL can alleviate acute
inflammation through inhibiting neutrophil transmigration
in a dose-dependent manner.
p-PGBL inhibits P-selectin binding to leucocytes in static
conditions In acute inflammation, leucocyte transmigration
is a multistep process, and P-selectin plays a critical role in
the initial leucocyte rolling and adhesion to endothelial cells.
Many studies have shown that the binding of P-selectin to
its ligands could be inhibited by several natural
carbohydrates[8,24,25]. To assess whether the effects of p-PGBL on
leucocyte transmigration in acute inflammation are due to
the inhibition of the interaction of P-selectin with its ligands,
we performed adhesion assays using HL-60 cells, which are
human leukemic cells expressing P-selectin ligand, and
human neutrophils by flow cytometry. As shown in Figure 3A
and 3B, P-selectin bound to HL-60 or neutrophils steadily,
and human P-selectin blocking mAb (9E1) could entirely
block the binding. At the concentrations of 0.1 g/L and 0.5
g/L, p-PGBL exhibited a strong inhibitory effect on P-selectin
binding. The results confirmed the involvement of P-selectin
in acute inflammation and indicated that p-PGBL could
inhibit P-selectin binding to its ligands.
p-PGBL inhibits neutrophil adhesion to CHO-P
To further investigate the molecular mechanisms of the
anti-inflammatory activity of p-PGBL, CHO-P cells steadily
expressing human P-selectin (Figure 4A) and CHO-P monolayers
cultured in a 35 mm plate (Figure 4B) were prepared to mimic
the activated VEC. Then the inhibitory effect of p-PGBL was
examined under a condition that was close to the
physiological blood flow rate (0.12 Pa). As illustrated in Figure 4C,
p-PGBL exhibited a strong inhibitory effect on neutrophils
rolling and adhesion to CHO-P cells at the concentrations of
0.1 g/L and 0.5 g/L. Compared with the positive control, the
inhibitory rates of p-PGBL at the concentrations of 0.1 g/L
and 0.5 g/L were 71.38% and 87.61%, respectively. These
findings indicate that under a physiological blood flow rate,
p-PGBL can inhibit P-selectin-mediated leucocyte adhesion
in a dose-dependent manner.
p-PGBL inhibits neutrophil adhesion to HUVEC
VEC, when stimulated or activated, can express P-selectin to
mediate leucocyte adhesion[2,26]. To investigate the
anti-inflammatory effect of p-PGBL under physiological conditions, we
further examined the interaction of neutrophils and HUVEC.
As illustrated in Figure 5, the treatment of HUVEC
monolayers (Figure 5A) with human thrombin (1 U/mL) dramatically
increased the number of neutrophil rolling and adhesion to
HUVEC, and blocking mAb to P-selectin (9E1) partly
inhibited neutrophil rolling and adhesion; p-PGBL, at the
concentrations of 0.1 g/L and 0.5 g/L, dramatically inhibited the
rolling and adhesion. These results showed that the
inhibition of p-PGBL in neutrophil adhesion to HUVEC is mainly
P-selectin mediated.
Discussion
Plant polysaccharides are natural, non-toxic substances
with multiple biological activities. Many plant
polysaccha-rides, such as Radix astragali,
Lentinus edodes, and Agaricus blazei
Muri, have been shown to possess anti-acute inflammatory
effects[27_29]. Song et al found that rough PGBL
exhibit evident anti-inflammatory activity due to the
inhibition of ear swelling and the capillary permeability in mice,
but the mechanism has not been clearly understood as
yet[15]. In the present study, the rough PGBL was further
purified by gel chromatography, and the purified fraction was
found to have a uniform molecular weight (Figure 1). The
anti-inflammatory effect of p-PGBL was detected by
examining the ear edema in mice and peritoneal transmigration of
neutrophils in the mouse acute inflammatory model. We found
that p-PGBL could significantly decrease ear edema in mice
and peritoneal deposition of neutrophils in a
dose-dependent manner (Figure 2A, 2B). Compared with the findings of
Song et al, our p-PGBL could preserve better
anti-inflammatory activity even at a lower concentration due to the
inhibition of ear edema and the blockage of neutrophil
transmigration.
It has been widely reported that P-selectin plays a critical
role in initial leucocyte rolling and adhesion to endothelial
cells on the inflammatory sites by interacting with its major
ligand PSGL-1[30,31]. Any antagonist that can block the
interaction of P-selectin and its ligands is likely to be effective in
inhibiting the inflammatory
process[32,33]. Here, we showed that p-PGBL can effectively block the interaction between
P-selectin and HL-60 cells or neutrophils (Figure 3A, 3B),
implying that the inhibitory effect of p-PGBL in
anti-inflammation is mainly due to the interference of P-selectin binding to
its ligands. This observation was further confirmed with
CHO-P and HUVEC cells by the flow chamber assay
conducted under physiological conditions (Figures 4,5).
Leukocyte recruitment during acute and chronic
inflammatory responses is a multistep process regulated by a
variety of adhesion molecules and inflammatory
factors[34]. In in vitro
experiments, we found that P-selectin blocking mAb
(9E1) almost totally blocked the adhesion of neutrophils to
CHO-P, but only partly blocked the adhesion of neutrophils
to HUVEC (Figures 4C,5B), implying that other adhesion
molecules on HUVEC also functioned in the rolling process.
Our results also showed that p-PGBL could more effectively
block the adhesion of neutrophils to HUVEC than P-selectin
blocking mAb, suggesting that, besides P-selectin, p-PGBL
also interfered with the interactions of other adhesion
molecules or inflammatory factors in this process. These results
were also confirmed by the ear edema in mice and acute
peritonitis experiments in vivo (Figure 2A,2B). We also found
that at a concentration of 0.01g/L, p-PGBL could effectively
inhibit neutrophil adhesion to HUVEC in vitro
(Figure 5B), but the inhibitory effects of p-PGBL on neutrophil
transmigration in vivo was not obvious at the concentration of 0.5
mg/kg, approximating to 0.01g/L (1 mL blood/20 g weight
mouse; Figure 2B). These results indicated that a higher
concentration of p-PGBL is required for inhibiting
neutrophil transmigration and inflammation in
vivo.
Inflammation can be divided into specific and
non-specific. At present, we still have not obtained better drugs
to treat non-specific inflammation. Although some drugs,
such as hormones, have been effective in treating
non-specific inflammation diseases, they exhibited strong side-effects.
As a natural, non-toxic substance, p-PGBL has demonstrated
its effect in inhibiting neutrophil transmigration and
inflammation in vivo. We believe that p-PGBL is a promising drug
for the clinical application of non-specific inflammation
diseases by offering higher efficiency and reducing side-effects.
Acknowledgements
Special thanks to Jing-feng YANG and Prof Zhong-yan
LIANG from the Normal University of Northeast China for
their technical support on the polysaccharide extraction from
the Ginkgo biloba leaves.
References
1 Steeber DA, Tedder TF. Adhesion molecule cascades direct
lymphocyte recirculation and leukocyte migration during
inflammation. Immunol Res 2000; 22: 299_317.
2 Ley K, Reutershan J. Leucocyte_endothelial interactions in
health and disease. Handb Exp Pharmacol 2006; 176: 97_133.
3 Ley K. The role of selectins in inflammation and disease. Trends
Mol Med 2003; 9: 263_8.
4 McEver RP. Properties of GMP-140, an inducible granule
membrane protein of platelets and endothelium. Blood Cells 1990;
16: 73_83.
5 Ludwig RJ, Schön MP, Boehncke WH. P-selectin: a common
therapeutic target for cardiovascular disorders, inflammation and
tumour metastasis. Expert Opin Ther Targets 2007; 11:
1103_17.
6 Lorant DE, Topham MK, Whatley RE, McEver RP, McIntyre
TM, Prescott SM, et al. Inflammatory roles of P-selectin. J
Clin Invest 1993; 92: 559_70.
7 Jung U, Ley K. Mice lacking two or all three selectins
demonstrate overlapping and distinct functions for each selectin. J
Immunol 1999; 162: 6755_62.
8 Wang L, Brown JR, Varki A, Esko JD. Heparin's
anti-inflammatory effects require glucosamine 6-O-sulfation and are mediated
by blockade of L- and P-selectins. J Clin Invest 2002; 110:
127_36.
9 Watson SR, Fennie C, Lasky LA. Neutrophil influx into an
inflammatory site inhibited by a soluble homing receptor-IgG
chimera. Nature 1991; 349: 164_7.
10 Bendas G. Inhibitors of membrane receptors involved with
leucocyte extravasation. Mini Rev Med Chem 2005; 5: 575_84.
11 Ushakova NA, Preobrazhenskaya ME, Bird MI, Priest R,
Semenov AV, Mazurov AV, et al. Monomeric and multimeric
blockers of selectins: comparison of in
vitro and in vivo activity. Biochemistry (Mosc) 2005; 70: 432_9.
12 Jin JQ, Ding DN, Bian XL. The study of chemical and
scavenging action to hydroxyl free radical of polysaccharides of
Ginkgo biloba leaf. J Xi'an Med Univ 2000; 21: 417_9 (in Chinese).
13 Liu X, Shen F, Yang XL. Effect of PLGB on activity of immune
cell in mice. J Shenyang Med Coll 1999; 1: 140_2 (in Chinese).
14 Chen Q, Liu TJ. Studies on immunomodulatory and
antineoplastic activities of polysaccharide isolated from
Ginkgo biloba leaf (GBLP). Pharmacol Clin Chin Mat Med 2003; 19: 18_9 (in
Chinese).
15 Song LY, Ma WX, Yu RM, Kan QM, Yao XS. Studies on the
biological activities of polysaccharides from the cell cultures and
the leaves of Ginkgo Biloba. Chin J Biochem Pharm 1999; 20:
278_80 (in Chinese).
16 Jaffe EA, Nachman RL, Becker CG, Minick RC. Culture of
human endothelial cells derived from umbilical vein. J Clin
Invest 1973; 52: 2745.
17 Kasper B, Brandt E, Ernst M, Petersen F. Neutrophil adhesion
to endothelial cells induced by platelet factor 4 requires
sequential activation of Ras, Syk, and JNK MAP kinases. Blood 2006;
107: 1768_75.
18 Gao YG, Li N, Fei R, Chen ZH, Zheng S, Zeng XL.
P-selectin-mediated acute inflammation can be blocked by chemically
modified heparin, RO-heparin. Mol Cells 2005; 19: 350_5.
19 Kraus J. Water-soluble polysaccharides from
Ginkgo biloba leaves. Phytochemistry 1991; 30: 301_2.
20 Wang ZJ, Luo DH, Liang ZY. Structure of polysaccharides from
the fruiting body of Hericium erinaceus
pers. Carbohyd Polym 2004; 57: 241_7.
21 Mathieu S, El-Battari A. Monitoring E-selectin-mediated
adhesion using green and red fluorescent proteins. J Immunol
Methods 2003; 272: 81_92.
22 Zhang P, Ding DL, Zhang H, Liu PL, Liu W, Zhang R,
et al. Study on anti-inflammatory and analgesic effects of arsenous
acid injection. J Harbin Med Univ 2004; 38: 531_6.
23 Yeo EL, Sheppard JI, Feuerstein IA. Role of P-selection and
leucocyte activation in polymorphonuclear cell adhesion to
surface adherent activated platelets under physiologic shear
conditions (an injury vessel wall model). Blood 1994; 83: 2498_507.
24 Lasky LA. Selectin: interpreters of cell specified carbohydrate
information during inflammation. Science 1992; 258: 964_9.
25 Kansas GS. Selectins and their ligands: current concepts and
controversies. Blood 1996; 88: 3259_64.
26 Ruiz-Torres MP, Pérez-Rivero G, Rodríguez-Puyol M,
Rodríguez-Puyol D, Díez-Marqués ML. The leukocyte_endothelial cell
interactions are modulated by extracellular matrix proteins. Cell
Physiol Biochem 2006; 17: 221_32.
27 Hao Y, Qiu QY, Wu J, Wang YG. Effect of
Astragalus polysaccharides in promoting neutrophil-vascular endothelial cell
adhesion and expression of related adhesive molecules. Chin J Integr
Trad West Med 2004; 24: 427_9 (in Chinese).
28 Zhao RJ, Zhao ZL, Wang D, Li LB, Jin ZN. Anti-inflammatory
effects of Agaricus Blazei Murill polysaccharide. J Med Sci
Yanbian Univ 2004; 27: 19_22 (in Chinese).
29 Ou-Yang XN, Yu ZY, Wang WW, Zhang X. Trial study on
anti-inflammatory effects of Lentinan. Acad J PLA Postgrad Med
Sch 2006; 27: 56_7 (in Chinese).
30 McEver RP, Cummings RD. Role of PSGL-1 binding to selectins
in leukocyte recruitment. J Clin Invest 1997; 100: 485_91.
31 Varki A. Selectin ligands. Proc Natl Acad Sci USA 1994; 91:
7390_7.
32 Kneuer C, Ehrhardt C, Radomski MW, Bakowsky U.
Selectins__potential pharmacological targets? Drug Discov Today
2006; 11: 1034_40.
33 Xie X, Rivier AS, Zakrzewicz A, Bernimoulin M, Zeng XL, Wessel
HP, et al. Inhibition of selectin-mediated cell adhesion and
prevention of acute inflammation by non-anticoagulant sulfated
saccharides. Studies with carboxyl-reduced and sulfated heparin
and with trestatin a sulfate. J Biol Chem 2000; 275: 34 818_25.
34 Radi ZA, Kehrli ME, Ackermann MR. Cell adhesion molecules,
leukocyte trafficking, and strategies to reduce leukocyte
infiltration. J Vet Intern Med 2001; 15: 516_29.
|
