sICAM-1 Release Research Articles

Human Rhinovirus Selectively Modulates Membranous and Soluble Forms of Its Intercellular Adhesion Molecule–1 (ICAM-1) Receptor to Promote Epithelial Cell Infectivity

Human rhinoviruses are responsible for many upper respiratory tract infections. 90% of rhinoviruses utilize intercellular adhesion molecule-1 (ICAM-1) as their cellular receptor, which also plays a critical role in recruitment of immune effector cells. Two forms of this receptor exist; membrane-bound (mICAM-1) and soluble ICAM-1 (sICAM-1). The soluble receptor may be produced independently from the membrane-bound form or it may be the product of proteolytic cleavage of mICAM-1. The ratio of airway epithelial cell expression of mICAM-1 to the sICAM-1 form may influence cell infectivity and outcome of rhinovirus infection. We therefore investigated the effect of rhinovirus on expression of both ICAM-1 receptors in normal human bronchial epithelial cells. We observed separate distinct messenger RNA transcripts coding for mICAM-1 and sICAM-1 in these cells, which were modulated by virus. Rhinovirus induced mICAM-1 expression on epithelial cells while simultaneously down-regulating sICAM-1 release, with consequent increase in target cell infectivity. The role of protein tyrosine kinases was investigated as a potential mechanistic pathway. Rhinovirus infection induced rapid phosphorylation of intracellular tyrosine kinase, which may be critical in up-regulation of mICAM-1. Elucidation of the underlying molecular mechanisms involved in differential modulation of both ICAM-1 receptors may lead to novel therapeutic strategies.

Implications of oxidative stress and inflammatory process in the cytotoxicity of capsaicin in human endothelial cells: lack of DNA strand breakage

Capsaicin, a natural product of Capsicum species is known to induce excitation of nociceptive terminals involved in pain perception. Nevertheless, it is utilized by topical application in humans, giving rise to blood capsaicin concentration up to 10–20 μM. The effect of capsaicin on human endothelial cells ECV 304 has been investigated. The cytotoxicity and inflammatory properties of capsaicin were evaluated by measuring the capsaicin-stimulated release of soluble intercellular adhesion molecule-1 levels (sICAM-1) into the culture medium; production of reactive oxygen species measured by quantification of lipoperoxidation in endothelial cell membranes; and genotoxicity measured using the comet assay and the DNA fragmentation assay. The concentration inhibiting protein synthesis by 50% after 24-h incubation was found to be 175 μM. Capsaicin induced an increase of sICAM-1 release into the culture medium at concentration ≥100 μM. Lipoperoxidation measured by malondialdehyde production increased at capsaicin concentration ≥200 μM. The comet test and DNA fragmentation assay clearly suggested that capsaicin does not induce significant DNA strand breaks within the range of concentrations used. Because the inflammatory reaction and lipid peroxidation may affect cellular functions and lead to cell death, the present data may have important implications for the possible health threats of capsaicin, specially in the case of unreasonable use of capsaicin preparations in pathological situations.

Release of Soluble ICAM-1 from Human Lung Fibroblasts, Aortic Smooth Muscle Cells, Dermal Microvascular Endothelial Cells, Bronchial Epithelial Cells, and Keratinocytes

We determined effects of IL-1α, TNFα and IFNγ on sICAM-1 release in culture media from human aortic smooth muscle cells (AOSMC), dermal microvascular endothelial cells (DMEC), keratinocytes (KC), bronchial epithelial cells (BEC) and lung fibroblasts (LF) as determined by ELISA. Under basal conditions of cultures for 20 h, low concentrations of sICAM-1 were only detected in the culture media of two (DMEC and BEC) of these cell types. IL-1α, TNFα and IFNγ stimulated sICAM-1 from these cells. IFNγ stimulated more shedding from AOSMC, BEC and KC than IL-1α or TNFα. TNFα enhanced more sICAM-1 release from DEMC than from AOSMC, BEC and LF. IL-1α and IFNγ or TNFα and IFNγ acted synergistically to enhance shedding of sICAM-1 from these cells. The levels sICAM-1 in pathophysiological conditions may influence leukocyte-vascular cell interactions to block leukocyte transmigration to tissue injury sites as a negative feedback mechanism.

In vitro analysis of the melanoma/endothelium interaction increasing the release of soluble intercellular adhesion molecule 1 by endothelial cells.

Melanoma cells constitutively release intercellular adhesion molecule 1 (ICAM-1) as soluble ICAM-1 (sICAM-1), and its levels are elevated in melanoma patients and correlate with disease progression. However, this correlation is not absolute, suggesting that specific characteristics of neoplastic cells and/or ICAM-1-positive non-neoplastic cells may influence the amounts of circulating sICAM-1. In this study, we found a weak correlation (r = 0.55; r2 = 0.3) between sICAM-1 release by 40 metastatic melanomas (36 primary cultures and 4 cell lines), and ICAM-1 expression on neoplastic cells. In addition, melanoma-secreted interleukin-1alpha (IL-1alpha) (1/40) but not vascular endothelial growth factor (VEGF) (29/40), significantly (P < 0.05) up-regulated the shedding of sICAM-1 by human umbilical vein endothelial cells (HUVEC). This was completely abolished by IL-1alpha/beta neutralizing antibodies both at the protein and mRNA level. Altogether, our results suggest that (i) the extent of sICAM-1 release is distinctive for individual melanomas and can be independent of ICAM-1 expression; (ii) tumor endothelia may sustain levels of sICAM-1 in selected melanomas; (iii) melanoma-released VEGF does not affect ICAM-1 expression and sICAM-1 release by HUVEC. Melanoma-derived sICAM-1 inhibits cell-mediated cytotoxicity of melanoma cells; therefore, constitutive levels of sICAM-1 release and IL-1alpha secretion by individual melanomas can differentially influence tumor progression and the clinical effectiveness of cytotoxic-cell-based vaccines.

Plasma soluble intercellular adhesion molecule-1 levels in coronary circulation in patients with unstable angina

It has been suggested that active inflammation plays an important role in the pathogenesis of acute coronary syndromes, including unstable angina. Intracellular adhesion molecule-1 (ICAM-1) is a major ligand on the endothelial cells for adherence of the activated polymorphonuclear leukocytes. Recently, it has been demonstrated that the soluble form of ICAM-1 has been detected in human serum and has been increased in many other inflammatory or autoimmune disorders. To evaluate the involvement of ICAM-1 in unstable angina, we examined plasma soluble ICAM-1 (sICAM-1) levels in coronary circulation. The plasma sICAM-1 levels in the coronary sinus and aortic root were simultaneously examined in 20 patients with unstable angina, 19 patients with stable exertional angina, and 16 control subjects. The plasma levels of sICAM-1 were measured by enzyme-linked immunosorbent assay. The mean plasma sICAM-1 levels (nanograms per milliliter) both in the coronary sinus and aortic root were significantly higher (p <0.01) in patients with unstable angina than in those with stable exertional angina and in control subjects (217 ± 14 vs 126 ± 8; 120 ± 10 in the coronary sinus, 202 ± 13 vs 125 ± 9; 123 ± 10 in the aortic root). Furthermore, the mean value was higher in the coronary sinus than in the aortic root in patients with unstable angina. There were no significant differences in the values between in the coronary sinus and aortic root in patients with stable exertional angina and control subjects. Thus, sICAM-1 release is increased, especially in coronary circulation in unstable angina.

Intercellular adhesion molecule‐1 on cultured human epithelial cell lines: influence of proinflammatory cytokines

The expression of intercellular adhesion molecule-1 (CD54 or ICAM-1) on epithelial cells during acute or chronic inflammation may favor the interaction between epithelial cells and leukocytes expressing the natural ligands of ICAM-1, LFA-1 (CD11a/CD18), and Mac-1 (CD11b/CD18). We have evaluated in vitro the expression of ICAM-1 by a conjunctival (WK) and an intestinal (I407) human continuous epithelial cell line. Cells were cultured for 24 h in the presence or absence of IFN-gamma, TNF-alpha, IL-1 beta, IL-4, IL-6, IL-8, IL-10, and TGF-beta 1. Both epithelial cell lines showed a constitutive expression of ICAM-1. IFN-gamma at 500 U/ml and TNF-alpha at 200 ng/ml upregulated ICAM-1 expression; IL-1 beta at 100 pg/ml upregulated ICAM-1 on WK cells only. Cells cultured in the presence of both IFN-gamma and TNF-alpha exhibited a mean fluorescence intensity far greater than those cultured with IFN-gamma or TNF-alpha alone. I407 and WK cells were able to release soluble ICAM-1. IFN-gamma and TNF-alpha enhanced the release of sICAM-1. IL-4, IL-6, IL-8, IL-10, and TGF-beta 1 did not affect either ICAM-1 expression or sICAM-1 release. In conclusion, continuously cultured human epithelial cells may express ICAM-1 on their surface and release it in culture medium. These phenomena are upregulated by proinflammatory cytokines.

Shed soluble ICAM-1 molecules in bronchoalveolar lavage cell supernatants and serum of patients with pulmonary sarcoidosis.

The soluble form of intercellular adhesion molecule-1 (sICAM-1) might be a serum parameter of inflammatory activity gauging cellular interactions with possible relevance in sarcoidosis. To address this question we measured sICAM-1 by enzyme-linked immunosorbent assay in serum and shedding of this molecule by bronchoalveolar lavage (BAL) cells in sarcoidosis patients (44 and 40, respectively) and in controls (10 and 19, respectively). Serum concentrations of sICAM-1 (588.3 +/- 72.2 ng/ml) and its spontaneous release by BAL cells (9.9 +/- 1.5 ng/ml) in patients with active sarcoidosis were significantly higher than in those with inactive disease or controls, although no correlation was observed. Significant correlations of sICAM-1 shedding by nonstimulated BAL cells with the serum level of neopterin and of shedding by lipopolysaccharide-stimulated BAL cells with percentage of alveolar macrophages were observed in active sarcoidosis. Kinetic cell culture experiments with peripheral blood mononuclears disclosed a rapid up-regulation of sICAM-1 shedding and tumor necrosis factor-alpha release; however, at 5 h after stimulation a dissociation of their releases was observed. sICAM-1 release was maintained over 2 days, whereas tumor necrosis factor-alpha release peaked at 5 and ceased after 43 h. These results provide evidence that circulating and BAL cell culture-derived sICAM-1 reflect the stage of sarcoid inflammation. Although sICAM-1 in BAL cell supernatants originates from alveolar macrophages; the absence of a correlation with serum sICAM-1 concentration indicates that other cells are additional sources of the circulating pool of this molecule.

989-57 Increased Plasma Soluble Intercellular Adhesion Molecule-1 (sICAM-1) Levels in Coronary Circulation in Patients with Unstable Angina

To determine whether plasma sICAM-1 levels increase in the coronary circulation in patients (pts) with unstable angina, we measured plasma sICAM-1 levels in the coronary sinus (CS) and aortic root (Ao) simultaneously in 18 unstable angina pts (UA), 18 stable exertional angina pts (SEA) and 14 control pts (Cont). Unstable angina was defined as worsening effort or rest angina, or both within 1 month of catherization. The three groups were matched for age and gender. The levels of sICAM-1 were measured by enzyme-linked immunosorbent assay. Data are shown below as means ± SE (ng/ml) UA SEA Cont CS 201 ± 16 * # 124 ± 8 119 ± 11 Ao 187 ± 15 * 123 ± 9 118 ± 11 * p &lt; 0.01 vs SEA and Cont # p &lt; 0.01 vs Ao The mean values of CS and Ao were significantly higher in UA than in SEA and in Cont. Furthermore, in UA the mean value was higher in CS than in Ao. There were no significant differences of the mean values of CS and Ao between SEA and Cont. We conclude that sICAM-1 release is increased especially in coronary circulation in UA. ICAM-1 is known to be a major ligand on endothelial cells for adherence of activated leukocyles. These results suggest that activation of leukocytes take place within coronary circulation, further may activate platelet and induce coronary thrombosis in UA

Soluble Intercellular Adhesion Molecule-1 in Arthritis

The objective of this study is to determine whether soluble intercellular adhesion molecule-1 (siCAM-l) is found in rheumatoid arthritis (RA) and other inflammatory disorders and to identify which cells are responsible for sICAM-1 production. Synovial fluid, blood and cells isolated from RA synovial fluids, and synovial tissues from 59 patients were studied. In addition, normal peripheral blood was obtained. sICAM-1 was assayed by an enzyme-linked immunoabsorbant assay. Synovial fluids from patients with RA and other inflammatory arthritides had significantly higher sICAM-1 levels than did osteoarthritis (OA) synovial fluids. Synovial fluid sICAM-1 levels were significantly positively correlated with synovial fluid leukocyte counts. RA synovial tissue fibroblasts released low levels of sICAM-1. Neutrophils (PMNs) isolated from synovial fluids of RA patients spontaneously released sICAM-1. However, mononuclear cells isolated from RA synovial fluid produced the largest quantities of sICAM-1. Phytohemagglutinin but not lipopolysaccharide enhanced mononuclear sICAM-1 release. sICAM-1 was increased in synovial fluids from RA compared to OA. This sICAM-1 may be important in modulating the trafficking of inflammatory leukocytes into diseased RA synovial tissue and fluid.