(Circulation. 2000;102:2165.)
© 2000 American Heart Association, Inc.
Brief Rapid Communications |
From the Department of Cardiology (E.T.H.Y.), University of TexasM.D. Anderson Cancer Center, Houston, Tex; Department of Internal Medicine (V.P., J.T.W., E.T.H.Y.) and Institute of Molecular Medicine for the Prevention of Human Diseases (E.T.H.Y.), University of Texas Health Science Center, Houston, Tex; and the Texas Heart Institute (V.P., J.T.W., E.T.H.Y.), St. Lukes Episcopal Hospital, Houston, Tex.
Correspondence to Edward T.H. Yeh, MD, Department of Cardiology, 1515 Holcombe Blvd, Box 70, University of TexasM.D. Anderson Cancer Center, Houston, TX 77030-4095.
| Abstract |
|---|
|
|
|---|
Methods and ResultsWe tested the effects of CRP on expression of
adhesion molecules in both human umbilical vein and coronary
artery endothelial cells. Expression of vascular cell
adhesion molecule (VCAM-1), intercellular adhesion molecule (ICAM-1),
and E-selectin was assessed by flow cytometry. Incubation with
recombinant human CRP (10 µg/mL) for 24 hours induced an
10-fold
increase in expression of ICAM-1 and a significant expression of
VCAM-1, whereas a 6-hour incubation induced significant E-selectin
expression. Adhesion molecule induction was similar to that observed in
endothelial cells activated with
interleukin-1ß. In coronary artery
endothelial cells, induction of ICAM-1 and VCAM-1 was
already present at 5 µg/mL and reached a maximum at 50 µg/mL,
at which point a substantial increase in expression of E-selectin was
also evident. The CRP effect was dependent on presence of human serum
in the culture medium, because no effect was seen in cells cultured
with serum-free medium. In contrast, interleukin-1ß was able to
induce adhesion molecule expression in the absence of human serum.
ConclusionsCRP induces adhesion molecule expression in human endothelial cells in the presence of serum. These findings support the hypothesis that CRP may play a direct role in promoting the inflammatory component of atherosclerosis and present a potential target for the treatment of atherosclerosis.
Key Words: cell adhesion molecules endothelium atherosclerosis
| Introduction |
|---|
|
|
|---|
| Methods |
|---|
|
|
|---|
Recombinant human CRP and highly purified CRP from human serum were purchased from Calbiochem. Purity of CRP preparations was confirmed by 12% SDS-PAGE; no contaminating proteins were detected by silver staining of overloaded gels. Interleukin-1ß (IL-1ß) was provided by RandD Systems (Minneapolis, Minn). Human serum and fetal bovine serum were purchased from Sigma.
Detection of Adhesion Molecules
Endothelial cells were incubated with human CRP
for the indicated time, and adhesion molecule expression was detected
by flow cytometry as previously described.7
The fluorescence intensity of 9000 cells for each sample was quantified by a fluorescence-activated cell sorter Calibur analyser (Becton Dickinson). Mean fluorescence intensity values were corrected for unspecific staining by subtracting the fluorescence of cells stained with the isotype antibody and were compared with the Kolmogorov-Smirnov statistics provided by Cellquest software. Cell viability was assessed by direct cell counting in a hemocytometer after staining with trypan blue.
Adhesion of the monocytoid cell line U937 to HUVECs was assessed according to a previously published protocol.8 Differences between groups were assessed by Mann-Whitney U test.
| Results |
|---|
|
|
|---|
10-fold increase in the mean fluorescent intensity of ICAM-1
(from 43 to 405 mean fluorescence intensity) and a significant
expression of VCAM-1 (from 0 at baseline to 31 mean
fluorescence intensity) (Figure 1A
1 to 28, Figure 1E
|
The biological significance of the adhesion molecule expression was confirmed by the significant increase of adhesion of U937 cells to HUVECs treated with 10 µg/mL CRP for 24 hours (from 1.7±1.2 cells in a 20x magnification field to 6.8±3.1 cells, P=0.005, mean of 6 fields).
Dose Response of CRP Effects in HCAECs
To extend our observations from HUVECs to arterial
endothelial cells involved in the pathogenesis of
atherosclerosis, we performed a dose-response
experiment in cultured HCAECs. Unstimulated HCAECs express significant
levels of ICAM-1, no VCAM-1, and low levels of E-selectin. The
dose-response relationship for the effect of CRP on ICAM-1, VCAM-1, and
E-selectin expression in HCAECs is shown in Figure 2
(A through I). The effect of CRP on
ICAM-1 and VCAM-1 was already present at a concentration of 5
µg/mL and was maximal at 50 µg/mL, whereas an increase in
E-selectin expression was evident only at concentrations >10 µg/mL,
with a significant increase at 50 µg/mL. An increase of CRP
concentration up to 100 µg/mL resulted in only a modest increase in
induction of adhesion molecules.
|
Proinflammatory Effect of CRP Is Dependent on Serum
The results described above were achieved in the presence of 15%
human serum. Intriguingly, HUVECs cultured in serum-free medium did not
respond to 100 µg/mL CRP (Figure 2L
, 2M
, and 2N
). This was not due to the inability of HUVECs to express
adhesion molecules in the absence of serum, because IL-1ß (10 ng/mL)
induced adhesion molecule expression under the same conditions (Figure 2L
, 2M
, and 2N
). The effects of CRP on
endothelial cells did not depend on the presence of LDL
or lipoproteins in the serum, because a similar induction of adhesion
molecules was observed with lipoprotein-free human serum (data not
shown).
| Discussion |
|---|
|
|
|---|
High levels of CRP are frequently observed in unstable angina and acute myocardial infarction.6 In patients with unstable angina, serum levels >3 µg/mL are associated with increased risk of coronary events, and the association is stronger for patients with serum levels >10 µg/mL.6 Subsequent large epidemiological studies have shown that even small increases in serum levels of CRP are associated with higher risk of atherosclerosis and ischemic heart disease in apparently healthy subjects.9 10 Similarly, in patients with stable angina, serum levels of CRP >3.6 µg/mL are associated with a 2-fold increase in the risk of coronary events.5
Although there is now strong evidence that serum CRP levels are an
independent risk factor for ischemic heart
disease,4 10 the mechanisms underlying this association
are not clear. Because inflammatory responses play an important role in
the development and evolution of atherosclerosis and
may contribute to its thrombotic complications, serum CRP may be merely
a marker of inflammatory response. Alternatively, CRP may have a direct
role in the pathogenesis of
atherosclerosis.4 11 Because of its
ligand-binding properties, CRP plays a part in innate immunity
(opsonization) and in the removal of membrane and nuclear material from
necrotic cells. CRP can also bind to complement factor C1q and factor H
and activate the classic pathway of complement
activation.12 In addition, recent studies13
have shown that CRP can bind to receptor FC
RI (with low affinity)
and FC
RII (with high affinity) on leukocytes. Interestingly, CRP is
present in atherosclerotic plaques, where it may colocalize with
the terminal complement complex.14 CRP can also induce
tissue factor expression by human monocytes.15
We found that CRP, at concentrations
5 µg/mL, has significant
proinflammatory effects in both umbilical vein and coronary
artery endothelial cells, inducing high levels of
expression of ICAM-1, VCAM-1, and E-selectin. These findings compare
well with the results of previous large prospective studies showing
increased risk of cardiac events in patients with angina in the upper
quintile of CRP concentrations (ie, >3.6 µg/mL).5
Similarly, in patients with unstable angina, high serum CRP levels at
discharge and high CRP levels during follow-up are associated with
increased risk of new coronary events, especially in patients
in the upper tertile of serum CRP levels (>8.6
µg/mL).16 Our results suggest that the proinflammatory
effects of CRP may contribute to the adverse outcome associated with
higher levels of this acute-phase reactant. The increased expression of
adhesion molecules in the vascular wall is an important factor in the
development of atherosclerosis and may enhance the
local inflammatory response within atherosclerotic plaques by
recruiting monocytes and lymphocytes.17 Lowering serum CRP
levels may have beneficial effects on the evolution of
atherosclerosis and may reduce the risk of
coronary events. In a recent trial, long-term treatment with
statins was associated with a reduction in serum CRP levels and in
better clinical outcome after acute myocardial
infarction.18
The mechanisms of the proinflammatory effects of CRP on
endothelial cells are not completely clear. Indeed,
HUVECs do not express the receptors FC
RI and FC
RII, which have
been shown to bind to CRP. Furthermore, our results clearly show that
the effects of CRP are dependent on the presence of serum. Thus, it is
possible that CRP effects are dependent on 1 or more serum cofactors.
However, this mechanism does not appear to be species specific, because
similar results have been obtained with human and bovine serum (data
not shown). Further studies are needed to elucidate the basic
mechanisms of the proinflammatory effects of CRP on
endothelial cells.
In conclusion, CRP, at concentrations frequently observed in high-risk subjects and in patients with unstable angina, induces significant expression of adhesion molecules by human endothelial cells. These results suggest that CRP is not merely a marker of inflammation but has complex modulatory functions that may contribute to the development and evolution of inflammation/atherosclerosis.
| Footnotes |
|---|
Received August 10, 2000; revision received September 8, 2000; accepted September 12, 2000.
| References |
|---|
|
|
|---|
activators. Circulation. 2000;101:235238.
receptor
II. J Exp Med. 1999;190:585590.
4 integrin and ICAM-1 markedly attenuate
macrophage homing to atherosclerotic plaques in ApoE-deficient
mice. Circulation. 1998;97:7581.This article has been cited by other articles:
![]() |
T. B. Grammer, W. Marz, W. Renner, B. O. Bohm, and M. M. Hoffmann C-reactive protein genotypes associated with circulating C-reactive protein but not with angiographic coronary artery disease: the LURIC study Eur. Heart J., May 21, 2008; (2008) ehn191v1. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Ortolani, A. Marzocchi, C. Marrozzini, T. Palmerini, F. Saia, N. Taglieri, F. Baldazzi, S. Silenzi, M. L. Bacchi-Reggiani, P. Guastaroba, et al. Predictive value of high sensitivity C-reactive protein in patients with ST-elevation myocardial infarction treated with percutaneous coronary intervention Eur. Heart J., May 2, 2008; 29(10): 1241 - 1249. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Nagaoka, L. Kuo, Y. Ren, A. Yoshida, and T. W. Hein C-Reactive Protein Inhibits Endothelium-Dependent Nitric Oxide-Mediated Dilation of Retinal Arterioles via Enhanced Superoxide Production Invest. Ophthalmol. Vis. Sci., May 1, 2008; 49(5): 2053 - 2060. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. J. Bunch, C. S. Rihal, R. J. Gumina, L. Cooper, and N. M. Caplice Progression of Nonculprit Plaque Stenosis Following Successful Percutaneous Intervention Angiology, May 1, 2008; 59(2): 236 - 239. [Abstract] [PDF] |
||||
![]() |
D. Gozal and L. Kheirandish-Gozal Cardiovascular Morbidity in Obstructive Sleep Apnea: Oxidative Stress, Inflammation, and Much More Am. J. Respir. Crit. Care Med., February 15, 2008; 177(4): 369 - 375. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. R. S. Packard and P. Libby Inflammation in Atherosclerosis: From Vascular Biology to Biomarker Discovery and Risk Prediction Clin. Chem., January 1, 2008; 54(1): 24 - 38. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. Xing, F. G. Hage, Y.-F. Chen, M. A. McCrory, W. Feng, G. A. Skibinski, E. Majid-Hassan, S. Oparil, and A. J. Szalai Exaggerated Neointima Formation in Human C-Reactive Protein Transgenic Mice Is IgG Fc Receptor Type I (Fc{gamma}RI)-Dependent Am. J. Pathol., January 1, 2008; 172(1): 22 - 30. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Haugen, I. P. Casserly, J. G. Regensteiner, and W. R. Hiatt Risk assessment in the patient with established peripheral arterial disease Vascular Medicine, November 1, 2007; 12(4): 343 - 350. [Abstract] [PDF] |
||||
![]() |
S. M. Nelson, N. Sattar, D. J. Freeman, J. D. Walker, and R. S. Lindsay Inflammation and Endothelial Activation Is Evident at Birth in Offspring of Mothers With Type 1 Diabetes Diabetes, November 1, 2007; 56(11): 2697 - 2704. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Sander, C. Schulze Horn, C. Briesenick, and D. Sander High-Sensitivity C-Reactive Protein Is Independently Associated With Early Carotid Artery Progression in Women But Not in Men: The INVADE Study Stroke, November 1, 2007; 38(11): 2881 - 2886. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Groschel, U. Ernemann, J. Larsen, M. Knauth, F. Schmidt, J. Artschwager, and A. Kastrup Preprocedural C-Reactive Protein Levels Predict Stroke and Death in Patients Undergoing Carotid Stenting AJNR Am. J. Neuroradiol., October 1, 2007; 28(9): 1743 - 1746. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. A. Cooper, A. Whaley-Connell, J. Habibi, Y. Wei, G. Lastra, C. Manrique, S. Stas, and J. R. Sowers Renin-angiotensin-aldosterone system and oxidative stress in cardiovascular insulin resistance Am J Physiol Heart Circ Physiol, October 1, 2007; 293(4): H2009 - H2023. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. N. Patel, C. A. King, S. R. Bailey, J. W. Holt, K. Venkatachalam, A. Agrawal, A. J. Valente, and B. Chandrasekar Interleukin-17 Stimulates C-reactive Protein Expression in Hepatocytes and Smooth Muscle Cells via p38 MAPK and ERK1/2-dependent NF-{kappa}B and C/EBPbeta Activation J. Biol. Chem., September 14, 2007; 282(37): 27229 - 27238. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Anan, T. Masaki, Y. Umeno, T. Iwao, H. Yonemochi, N. Eshima, T. Saikawa, and H. Yoshimatsu Correlations of high-sensitivity C-reactive protein and atherosclerosis in Japanese type 2 diabetic patients Eur. J. Endocrinol., September 1, 2007; 157(3): 311 - 317. [Abstract] [Full Text] [PDF] |
||||
![]() |
I. Barutcu, A. T. Sezgin, N. Sezgin, H. Gullu, A. M. Esen, E. Topal, R. Ozdemir, F. Kosar, and S. Cehreli Increased High Sensitive CRP Level and Its Significance in Pathogenesis of Slow Coronary Flow Angiology, September 1, 2007; 58(4): 401 - 407. [Abstract] [PDF] |
||||
![]() |
S. Liu, L. Tinker, Y. Song, N. Rifai, D. E. Bonds, N. R. Cook, G. Heiss, B. V. Howard, G. S. Hotamisligil, F. B. Hu, et al. A Prospective Study of Inflammatory Cytokines and Diabetes Mellitus in a Multiethnic Cohort of Postmenopausal Women Arch Intern Med, August 13, 2007; 167(15): 1676 - 1685. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. M. Andrei, R. Fraguas Jr., R. M.S. Telles, T. C.T.F. Alves, C. M.C. Strunz, A. Nussbacher, J. Rays, D. V. Iosifescu, and M. Wajngarten Major Depressive Disorder and Inflammatory Markers in Elderly Patients With Heart Failure Psychosomatics, August 1, 2007; 48(4): 319 - 324. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Teoh, A. Quan, and S. Verma Does C-reactive protein predict saphenous vein graft patency? J. Thorac. Cardiovasc. Surg., August 1, 2007; 134(2): 277 - 279. [Full Text] [PDF] |
||||
![]() |
A. Momin, N. Melikian, S. B. Wheatcroft, D. Grieve, L. C. John, A. El Gamel, M. T. Marrinan, J. B. Desai, C. Driver, R. Sherwood, et al. The association between saphenous vein endothelial function, systemic inflammation, and statin therapy in patients undergoing coronary artery bypass surgery J. Thorac. Cardiovasc. Surg., August 1, 2007; 134(2): 335 - 341. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Muniyappa, M. Montagnani, K. K. Koh, and M. J. Quon Cardiovascular Actions of Insulin Endocr. Rev., August 1, 2007; 28(5): 463 - 491. [Abstract] [Full Text] [PDF] |
||||
![]() |
M Rosvall, G Engstrom, L Janzon, G Berglund, and B Hedblad The role of low grade inflammation as measured by C-reactive protein levels in the explanation of socioeconomic differences in carotid atherosclerosis Eur J Public Health, August 1, 2007; 17(4): 340 - 347. [Abstract] [Full Text] [PDF] |
||||
![]() |
D.C.Y. Yeung, A. Xu, C.W.S. Cheung, N.M.S. Wat, M.H. Yau, C.H.Y. Fong, M.T. Chau, and K.S.L. Lam Serum Adipocyte Fatty Acid-Binding Protein Levels Were Independently Associated With Carotid Atherosclerosis Arterioscler. Thromb. Vasc. Biol., August 1, 2007; 27(8): 1796 - 1802. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Song, J. E. Manson, L. Tinker, N. Rifai, N. R. Cook, F. B. Hu, G. S. Hotamisligil, P. M. Ridker, B. L. Rodriguez, K. L. Margolis, et al. Circulating Levels of Endothelial Adhesion Molecules and Risk of Diabetes in an Ethnically Diverse Cohort of Women Diabetes, July 1, 2007; 56(7): 1898 - 1904. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Grad, M. Golomb, I. Mor-Yosef, N. Koroukhov, C. Lotan, E. R. Edelman, and H. D. Danenberg Transgenic expression of human C-reactive protein suppresses endothelial nitric oxide synthase expression and bioactivity after vascular injury Am J Physiol Heart Circ Physiol, July 1, 2007; 293(1): H489 - H495. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. D. Knudson, G. M. Dick, and J. D. Tune Adipokines and Coronary Vasomotor Dysfunction Experimental Biology and Medicine, June 1, 2007; 232(6): 727 - 736. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Ryan, G. M Nolan, E. Hannigan, S. Cunningham, C. Taylor, and W. T McNicholas Cardiovascular risk markers in obstructive sleep apnoea syndrome and correlation with obesity Thorax, June 1, 2007; 62(6): 509 - 514. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. W. Lorenz, P. Karbstein, H. S. Markus, and M. Sitzer High-Sensitivity C-Reactive Protein Is Not Associated With Carotid Intima-Media Progression: The Carotid Atherosclerosis Progression Study Stroke, June 1, 2007; 38(6): 1774 - 1779. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Lavi, J. P. McConnell, C. S. Rihal, A. Prasad, V. Mathew, L. O. Lerman, and A. Lerman Local Production of Lipoprotein-Associated Phospholipase A2 and Lysophosphatidylcholine in the Coronary Circulation: Association With Early Coronary Atherosclerosis and Endothelial Dysfunction in Humans Circulation, May 29, 2007; 115(21): 2715 - 2721. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. E. Szmitko and S. Verma C-Reactive Protein and Reendothelialization: NO Involvement Circ. Res., May 25, 2007; 100(10): 1405 - 1407. [Full Text] [PDF] |
||||
![]() |
M. V. Jimenez, R. M. Estepa, R. M. Camacho, R. C. Estrada, F. G. Luna, and F. B. Guitarte Endothelial dysfunction is related to insulin resistance and inflammatory biomarker levels in obese prepubertal children Eur. J. Endocrinol., April 1, 2007; 156(4): 497 - 502. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Palmerini, A. Marzocchi, C. Marrozzini, L. B. Reggiani, C. Savini, G. Marinelli, R. Di Bartolomeo, and A. Branzi Preoperative C-reactive protein levels predict 9-month mortality after coronary artery bypass grafting surgery for the treatment of left main coronary artery stenosis Eur. J. Cardiothorac. Surg., April 1, 2007; 31(4): 685 - 690. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Oren, A. R. Erbay, M. Balci, and S. Cehreli Role of Novel Biomarkers of Inflammation in Patients With Stable Coronary Heart Disease Angiology, April 1, 2007; 58(2): 148 - 155. [Abstract] [PDF] |
||||
![]() |
R. J. Bisoendial, J. J. P. Kastelein, S. L. M. Peters, J. H. M. Levels, R. Birjmohun, J. I. Rotmans, D. Hartman, J. C. M. Meijers, M. Levi, and E. S. G. Stroes Effects of CRP infusion on endothelial function and coagulation in normocholesterolemic and hypercholesterolemic subjects J. Lipid Res., April 1, 2007; 48(4): 952 - 960. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Tabuchi, K. Inoue, H. Usui-Kataoka, K. Kobayashi, M. Teramoto, K. Takasugi, K. Shikata, M. Yamamura, K. Ando, K. Nishida, et al. The association of C-reactive protein with an oxidative metabolite of LDL and its implication in atherosclerosis J. Lipid Res., April 1, 2007; 48(4): 768 - 781. [Abstract] [Full Text] [PDF] |
||||
![]() |
O. Schlager, M. Exner, W. Mlekusch, S. Sabeti, J. Amighi, P. Dick, O. Wagner, R. Koppensteiner, E. Minar, and M. Schillinger C-Reactive Protein Predicts Future Cardiovascular Events in Patients With Carotid Stenosis Stroke, April 1, 2007; 38(4): 1263 - 1268. [Abstract] [Full Text] [PDF] |
||||
![]() |
M.-F. Tsan and Baochong Gao Review: Pathogen-associated molecular pattern contamination as putative endogenous ligands of Toll-like receptors Innate Immunity, February 1, 2007; 13(1): 6 - 14. [Abstract] [PDF] |
||||
![]() |
C. Rocker, D. E. Manolov, E. V. Kuzmenkina, K. Tron, H. Slatosch, J. Torzewski, and G. U. Nienhaus Affinity of C-Reactive Protein toward Fc{gamma}RI Is Strongly Enhanced by the {gamma}-Chain Am. J. Pathol., February 1, 2007; 170(2): 755 - 763. [Abstract] [Full Text] [PDF] |
||||
![]() |
|