Human eosinophil adherence to vascular endothelium mediated by binding to vascular cell adhesion molecule 1 and endothelial leukocyte adhesion molecule 1.

Adherence of human eosinophils to cytokine-stimulated endothelial cells, which was only partially due to CD18-dependent pathways, was also mediated by binding to endothelial leukocyte adhesion molecule 1 (ELAM-1) and vascular cell adhesion molecule 1 (VCAM-1). Eosinophils bound specifically to both recombinant soluble ELAM-1 and recombinant soluble VCAM-1. Eosinophil binding to recombinant soluble VCAM-1 and to transfected CHO cells expressing VCAM-1 was inhibited with anti-VCAM-1 (4B9) and anti-very late activation antigen 4 (anti-VLA-4; HP1/2 or HP2/1) monoclonal antibodies. Eosinophils, but not neutrophils, expressed VLA-4 detected by cytofluorography. Eosinophil adherence to tumor necrosis factor alpha-stimulated human umbilical vein endothelial cells was partially blocked by monoclonal antibodies against ELAM-1 (BB11) and VCAM-1 (4B9) and against VLA-4 (HP2/1). Thus, while both eosinophils and neutrophils can bind to activated endothelial cells by adherence to ICAM-1 and ELAM-1, only eosinophils expressed VLA-4 and adhered to VCAM-1 on activated endothelial cells. Eosinophil adherence to VCAM-1 might provide a mechanism contributing to the selective recruitment of eosinophils into tissue sites of inflammation.     

Human dermal mast cells contain and release tumor necrosis factor alpha, which induces endothelial leukocyte adhesion molecule 1.

Tumor necrosis factor alpha (TNF-alpha) is a proinflammatory cytokine that mediates endothelial leukocyte interactions by inducing expression of adhesion molecules. In this report, we demonstrate that human dermal mast cells contain sizeable stores of immunoreactive and biologically active TNF-alpha within granules, which can be released rapidly into the extracellular space upon degranulation. Among normal human dermal cells, mast cells are the predominant cell type that expresses both TNF-alpha protein and TNF-alpha mRNA. Moreover, induction of endothelial leukocyte adhesion molecule 1 expression is a direct consequence of release of mast cell-derived TNF-alpha. These findings establish a role for human mast cells as "gatekeepers" of the dermal microvasculature and indicate that mast cell products other than vasoactive amines influence endothelium in a proinflammatory fashion.     

E-selectin and vascular cell adhesion molecule-1 mediate adult T-cell leukemia cell adhesion to endothelial cells

We studied the adhesion properties of peripheral blood leukemic cells from 10 patients with adult T-cell leukemia (ATL) to endothelial cells to better understand the mechanism of leukemic cell infiltration. ATL cells expressed lymphocyte function-associated antigen-1 (LFA-1), but the expression of very late antigen-4 (VLA-4) and sialyl-Lewisx (SLex) was variable. They did not express sialyl-Lewisa (SLea). Cell adhesion assays, which were performed in nine patients, showed marked adhesion of ATL cells to interleukin [IL]-1-activated human umbilical vein endothelial cells (HUVEC). A monoclonal antibody (MoAb) against E- selectin consistently inhibited ATL cell adhesion, and an MoAb against vascular cell adhesion molecule-1 (VCAM-1) or an MoAb against VLA-4 sometimes diminished it. In contrast, an MoAb against LFA-1 had a minor effect on freshly isolated ATL cell adhesion to HUVEC. The percentage of SLex+ cells in the cell population adherent to IL-1-activated HUVEC was slightly higher than that in unseparated cells. These results, together with the detection of E-selectin expression on the endothelium at ATL skin lesions, indicate that E-selectin-mediated adhesion is the major pathway for the adherence of ATL cells to endothelial cells. In addition, the ligand for E-selectin on ATL cells appears to differ from that on neutrophils.     

MicroRNA-126 regulates endothelial expression of vascular cell adhesion molecule 1

Adhesion molecules expressed by activated endothelial cells play a key role in regulating leukocyte trafficking to sites of inflammation. Resting endothelial cells normally do not express adhesion molecules, but cytokines activate endothelial cells to express adhesion molecules such as vascular cell adhesion molecule 1 (VCAM-1), which mediate leukocyte adherence to endothelial cells. We now show that endothelial cells express microRNA 126 (miR-126), which inhibits VCAM-1 expression. Transfection of endothelial cells with an oligonucleotide that decreases miR-126 permits an increase in TNF-alpha-stimulated VCAM-1 expression. Conversely, overexpression of the precursor to miR-126 increases miR-126 levels and decreases VCAM-1 expression. Additionally, decreasing endogenous miR-126 levels increases leukocyte adherence to endothelial cells. These data suggest that microRNA can regulate adhesion molecule expression and may provide additional control of vascular inflammation.     

Elevated expression of beta 1 and beta 2 integrins, intercellular adhesion molecule 1, and endothelial leukocyte adhesion molecule 1 in the skin of patients with systemic sclerosis of recent onset.

OBJECTIVE. To investigate the possible role of integrins and cell adhesion molecules in the pathogenesis of the mononuclear cell infiltration and fibrosis of skin that occurs in systemic sclerosis (SSc). METHODS. The presence and topographic distribution of beta 1, beta 2, and beta 4 integrins, as well as of endothelial leukocyte adhesion molecule 1 (ELAM-1) and intercellular adhesion molecule 1 (ICAM-1), was examined immunohistochemically in affected skin from 8 patients with rapidly progressive SSc of recent onset. The expression of the beta 1 integrin gene was also investigated by in situ hybridization with a human sequence-specific complementary DNA. RESULTS. The presence of beta 1 integrin epitopes and the corresponding messenger RNA within inflammatory cells surrounding small vessels was demonstrated in SSc skin but not in normal skin. Lymphocytes positive for beta 2 integrin were also found only in SSc skin, and they appeared in close proximity to small blood vessels and collagen bundles. Immunostaining for beta 4 integrin epitopes revealed no differences between normal and SSc skin. ELAM-1 and ICAM-1 monoclonal antibodies, which identify epitopes indicative of endothelial cell activation, stained endothelial cells in SSc skin but not normal skin. CONCLUSION. These observations suggest that the complex interactions of beta 1 and beta 2 integrins, as well as ELAM-1 and ICAM-1, may be intimately involved in the pathogenesis of SSc, perhaps by mediating the homing and targeting of pathogenetic lymphocytes to the affected tissues.     

Enzymatically modified, nonoxidized LDL induces selective adhesion and transmigration of monocytes and T-lymphocytes through human endothelial cell monolayers

Circulating monocytes and T lymphocytes extravasate through the endothelium at sites of developing atheromatous lesions, where they tend to accumulate and mediate the progression of the disease. We have previously demonstrated the presence of an enzymatically degraded, nonoxidized form of LDL (E-LDL) in early human fatty streaks, which possesses major biological properties of an atherogenic lipoprotein. The effects of E-LDL on human endothelial cells have now been studied with respect to adhesion and transmigration of monocytes and T lymphocytes. E-LDL induced a rapid and dose-dependent selective adhesion of monocytes and T lymphocytes to endothelial cell monolayers within 30 minutes of incubation. Maximal increases in the number of adherent monocytes (8-fold) and of adherent T lymphocytes (4-fold) were observed after treatment with 50 microg/mL E-LDL. E-LDL was more active than oxidized LDL (ox-LDL), whereas native LDL produced only minor adhesive effects. Both E-LDL and ox-LDL enhanced transmigration of monocytes and of T lymphocytes through endothelial monolayers. Again, E-LDL was more potent than ox-LDL, inducing transmigration to a similar extent as N-formyl-Met-Leu-Phe. In endothelial cells, E-LDL stimulated upregulation of intercellular adhesion molecule-1 (ICAM-1), platelet-endothelial cells adhesion molecule-1 (PECAM-1), P-selectin, and E-selectin with distinct kinetics. Analyses with blocking antibodies indicated that ICAM-1 and P-selectin together mediated approximately 70% of cell adhesion, whereas blocking of PECAM-1 had no effect on adhesion but reduced transmigration to less than 50% of controls. E-LDL also upregulated expression of ICAM-1 in human aortic smooth muscle cells, and this correlated with increased adhesion of T lymphocytes. E-LDL is thus able to promote the selective adhesion of monocytes and T lymphocytes to the endothelium, stimulate transmigration of these cells, and foster their retention in the vessel wall by increasing their adherence to smooth muscle cells. These findings underline the potential significance of E-LDL in the pathogenesis of atherosclerosis.     

Inhibition of lymphocyte adhesion to cytokine-activated synovial fibroblasts by glucocorticoids involves the attenuation of vascular cell adhesion molecule 1 and intercellular adhesion molecule 1 gene expression

Objective. The aim of this study was to evaluate the ability of glucocorticoids to inhibit lymphocyte adhesion to human synovial fibroblasts. Methods. Adhesion of lymphocytes to cultured synovial fibroblasts was measured by counting the number of cells bound to fibroblasts. Surface expression of intercellular adhesion molecule 1 (ICAM-1) was measured by enzyme-linked immunosorbent assay, while vascular cell adhesion molecule 1 (VCAM-1) surface expression was measured by flow cytometry. ICAM-1 and VCAM-1 messenger RNA (mRNA) levels were assessed by Northern blot analysis. Results. Stimulation of synovial fibroblasts by the proinflammatory cytokines tumor necrosis factor α, interleukin-1β, and interferon-γ resulted in a dose-dependent increase in lymphocyte adhesion to synovial fibroblasts. This response was inhibited by preincubation of the cells with the synthetic glucocorticoid dexa-methasone. Since lymphocyte adhesion to synovial fibroblasts is known to be mediated by VCAM-1 and ICAM-1, we examined the modulation of VCAM-1 and ICAM-1 expression in these cells. All 3 cytokines stimulated VCAM-1 and ICAM-1 surface and mRNA expression. Dexamethasone inhibited both VCAM-1 and ICAM-1 surface and mRNA expression in a dose-dependent manner, which correlated with the inhibition of lymphocyte adhesion. Conclusion. Taken together, these results suggest that glucocorticoids may reduce inflammatory responses at extravascular sites by inhibiting the expression of these adhesion molecules, thereby reducing the adhesion of lymphocytes to connective tissue cells.     

青藤碱对肿瘤坏死因子-α诱导人脐静脉内皮细胞VCAM-1表达影响初步研究

目的 进一步研究青藤碱(SIN)对肿瘤坏死因子(TNF)-α诱导脐静脉内皮细胞(HUVECs)血管细胞黏附分子(VCAM)-1表达的影响.方法 从新鲜脐带中分离培养HUVECs.用TNF-α诱导HUVECs表达VCAM-1,实验组加入不同浓度的SIN(0.25、0.0和1.0 mol/L)或地塞米松(1.0×106mol/L)分别进行或联合进行干预,用流式细胞仪检测细胞表面VCAM-1表达.结果 与TNF-α刺激组相比,SIN干预组细胞表面VCAM-1表达下降,抑制作用以1.0 mol/L最为显著.联合地塞米松(1.0x106 mol/L)进行干预,可加强SIN对TNF-α诱导的VCAM-1表达的抑制作用.结论 SIN可抑制TNF-α诱导的脐静脉内皮细胞VCAM-1的表达.青藤碱与地塞米松对TNF-α诱导的VCAM-1表达的抑制有协同作用.     

Amphotericin B induces expression of genes encoding chemokines and cell adhesion molecules in the human monocytic cell line THP-1

Amphotericin B is known to elicit immunomodulatory effects on neutrophil, monocyte, and lymphocyte function. It also has been shown to induce the release of proinflammatory cytokines from human monocytes and macrophages. Release of these cytokines has been associated with the infusion-related toxicity observed after administration of this drug. The present study demonstrates that amphotericin B increases mRNA for the chemokines interleukin (IL)-8, monocyte chemoattractant protein (MCP)-1, and macrophage inflammatory protein (MIP)-1beta, as well as the cell adhesion molecules intercellular adhesion molecule (ICAM)-1 and CD44 in the human monocytic cell line THP-1. Amphotericin B increased the concentrations of IL-8, MCP-1, and MIP-1beta in a dose-dependent fashion. Amphotericin B also induced expression of ICAM-1 but not CD44 in these cells. Production of these proteins in response to amphotericin B may play a role in the immunomodulatory activity and toxicity of this antifungal agent.