Soluble endothelial cell-selective adhesion molecule and incident cardiovascular events in a multiethnic population

BACKGROUND

Cell adhesion molecules are key regulators of atherosclerotic plaque development, but circulating levels of soluble fragments, such as intercellular adhesion molecule (sICAM-1) and vascular cell adhesion molecule (sVCAM-1), have yielded conflicting associations with atherosclerotic cardiovascular disease (ASCVD). Endothelial cell-selective adhesion molecule (ESAM) is expressed exclusively in platelets and endothelial cells, and soluble ESAM (sESAM) levels have been associated with prevalent subclinical atherosclerosis. We therefore hypothesized that sESAM would be associated with incident ASCVD.

METHODS

sESAM, sICAM-1, and sVCAM-1 were measured in 2,442 participants without CVD in the Dallas Heart Study, a probability-based population sample aged 30-65 years enrolled between 2000 and 2002. ASCVD was defined as first myocardial infarction, stroke, coronary revascularization, or CV death. A total of 162 ASCVD events were analyzed over 10.4 years.

RESULTS

Increasing sESAM was associated with ASCVD, independent of risk factors (HR Q4 vs Q1: 2.7, 95% CI 1.6-4.6). Serial adjustment for renal function, sICAM-1, VCAM-1, and prevalent coronary calcium did not attenuate these associations. Continuous ESAM demonstrated similar findings (HR 1.31, 95% CI 1.2-1.4). Addition of sESAM to traditional risk factors improved discrimination and reclassification (delta c-index: P = .009; integrated-discrimination-improvement index P = .001; net reclassification index = 0.42, 95% CI 0.15-0.68). Neither sICAM-1 nor sVCAM-1 was independently associated with ASCVD.

CONCLUSIONS

sESAM but not sICAM-1 or sVCAM-1 levels are associated with incident ASCVD. Further studies are warranted to investigate the role of sESAM in ASCVD.

Light-triggered in vivo activation of adhesive peptides regulates cell adhesion, inflammation and vascularization of biomaterials

Materials engineered to elicit targeted cellular responses in regenerative medicine must display bioligands with precise spatial and temporal control. Although materials with temporally regulated presentation of bioadhesive ligands using external triggers, such as light and electric fields, have recently been realized for cells in culture, the impact of in vivo temporal ligand presentation on cell-material responses is unknown. Here, we present a general strategy to temporally and spatially control the in vivo presentation of bioligands using cell-adhesive peptides with a protecting group that can be easily removed via transdermal light exposure to render the peptide fully active. We demonstrate that non-invasive, transdermal time-regulated activation of cell-adhesive RGD peptide on implanted biomaterials regulates in vivo cell adhesion, inflammation, fibrous encapsulation, and vascularization of the material. This work shows that triggered in vivo presentation of bioligands can be harnessed to direct tissue reparative responses associated with implanted biomaterials.

Adhesion molecules in radiotherapy

Recent studies have documented changes in adhesion molecule expression and function after exposure to ionizing radiation. Adhesion molecules mediate cell-cell and cell-matrix interactions and are essential for a variety of physiological and pathological processes including maintenance of normal tissue integrity as well as tumor development and progression. Consequently, modulation of adhesion molecules by radiation may have a role in radiation-induced tumor control and normal tissue damage by interfering with cell signaling, radioresistance, metastasis, angiogenesis, carcinogenesis, immune response, inflammation and fibrosis. In addition, the interactions of radiation with adhesion molecules could have a major impact in developing new strategies to increase the efficacy of radiation therapy. Remarkable progress has been made in recent years to design targeted drug delivery to radiation-up-regulated adhesion molecules. Furthermore, the inhibition of adhesion, migration, invasion and angiogenesis by blocking adhesion receptors may represent a new therapeutic approach to improve tumor control and decrease radiation toxicity. This review is focused on current data concerning the mechanistic interactions of radiation with adhesion molecules and the possible clinical-pathological implications in radiotherapy.

Changed adhesion molecule profile of Ewing tumor cell lines and xenografts under the influence of ionizing radiation

BACKGROUND

Adhesion molecules are involved in cell-cell and cell-matrix interactions and may be informative to characterize intercellular mechanisms of invasion and metastasis. This study was performed to characterize radiation-induced changes in the adhesion molecule profile of Ewing tumor subpopulations on a single cell level.

MATERIALS AND METHODS

In the present study, two Ewing tumors were characterized in vitro 4, 24 and 72 hours after radiation with 5 Gy and in vivo in a xenograft model 4, 6 and 15 days after radiation with 30 Gy, together with non-irradiated controls, by five parameter flow cytometry. Directly fluorescence-conjugated antibodies that were directed against adhesion molecules (LFA-1 (CD11a), HCAM (CD44), VLA-2 (CD49b), ICAM-1 (CD54), NCAM (CD56), LECAM-1 (CD62L) and CD86) were used. Annexin V and 7-AAD were used to characterize radiation-induced apoptosis.

RESULTS

Tumor cell subpopulations were identified by the expression of adhesion molecules, apoptotic markers and DNA content. Heterogeneous changes of the adhesion molecule profile were identified on tumor cell subpopulations after radiation. The expression of CD11a and CD62L correlated with the expression of apoptosis-associated markers.

CONCLUSION

The changes of flow cytometric profile under radiation may potentially correlate with a changed metastatic potential of tumor cell subpopulations.

Correlation of ionizing irradiation-induced late pulmonary fibrosis with long-term bone marrow culture fibroblast progenitor cell biology in mice homozygous deletion recombinant negative for endothelial cell adhesion molecules

Ionizing irradiation damage to the lung is associated with an acute inflammatory reaction, followed by a latent period and then late effects including predominantly pulmonary fibrosis. The cells mediating fibrosis have recently been shown to derive from the bone marrow hematopoietic microenvironment. Initiation of late pulmonary irradiation lung damage has been correlated with up-regulation of VCAM-1 and ICAM-1 in pulmonary endothelial cells, followed by infiltration of macrophages and bone marrow-derived fibroblasts forming the fibrotic lesions of organizing alveolitis/fibrosis. To determine whether the absence of expression of VCAM-1, ICAM-1, or other adhesion molecules known to be relevant to inflammatory cell attachment to lung endothelial cells was associated with a decrease in irradiation-induced lung fibrosis, homozygous deletion recombinant knockout mice lacking each of several adhesion molecules were tested compared to littermates for survival and development of organizing alveolitis following 20 Gy irradiation to both lungs. Bone marrow culture longevity has been shown to be a parameter, which correlates with both hematopoietic stem cell reserve and the integrity of fibroblast progenitors of the supportive hematopoietic microenvironment; radiation lung survival data were correlated to longevity of hematopoiesis in long-term bone marrow cultures established from tibia and femur bone marrow of the same mice. Homozygous deletion recombinant negative mice including VCAM-1-/-, ICAM-1-/-, E-Selectin-/-, or L-Selectin-/- were irradiated to 20 Gy to both lungs and followed for survival and percent organizing alveolitis at time of death compared to each normal littermate. A significant increase in survival (median 190 days) was detected with L-Selectin-/- compared to littermate control mice (median 140 days) or other groups. Long-term bone marrow cultures from L-Selectin-/- mice showed no detectable difference in marrow fibroblasts or hematopoietic cell biology compared to normal littermates; however, E-Selectin-/- mouse long-term bone marrow cultures showed an increase in total cumulative cell production (1.7 x 10(8) cells per flask) compared to bone marrow cultures from normal littermates (1.8 x 10(6) cells per flask) or other groups. As additional controls, transgenic Sod2 mouse long-term bone marrow cultures and those from HPV16, E6 and E7 cytokeratin 14 transgenic mice were also tested. No detectable difference in hematopoiesis was noted in these cultures compared to littermates. The results suggest a complex pattern of involvement of endothelial specific adhesion molecules and marrow fibroblasts in the cell biologic events associated with late irradiation pulmonary fibrosis.

Integrin Signalling and the Cellular Response to Ionizing Radiation

Cell survival and cycling in mammalian cells are both greatly affected by ionizing radiation and are both strictly controlled by integrated integrin-mediated adhesion to extracellular matrix (ECM) proteins and by binding of growth factors to their cognate receptors. Recent emerging findings show a diverse panel of integrin-dependent signals that are channelled into the regulation and modification of the cellular response to ionizing radiation. Cell adhesion-mediated radioresistance and alteration of DNA damage-induced cell cycle arrest in cells attached to the ECM can be linked to focal adhesion protein signalling. This review summarizes the latest radiobiological and radiooncological findings about integrins and their signal transduction pathways.

Targeting microparticles to select tissue via radiation-induced upregulation of endothelial cell adhesion molecules

PURPOSE

Certain endothelial cell adhesion molecules are up regulated in tissue that has been irradiated for therapeutic purposes. This up-regulation of adhesion molecules provides a potential avenue for targeting drugs to select tissues.

METHODS

Microspheres were coated with a mAb to ICAM-1 and the level of adhesion of the anti-ICAM-1 microspheres to irradiated tissue in vitro and in vivo was quantified.

RESULTS

Under in vitro flow conditions, the number of adherent microspheres on irradiated HUVEC was 4.8 +/- 0.9 times that of control; the adhesion of anti-ICAM-1 microspheres on irradiated HUVEC could be enhanced by more than 170% in the presence of RBC (20% hematocrit) in the medium. In vivo in a rat cranial window model, the number of adherent anti-ICAM-1 microspheres in locally irradiated cerebral tissue was 8 and 13 times that of IgG microspheres at 24 h and 48 h post-irradiation, respectively and returned to baseline 7 days post-irradiation. In locally irradiated animals, the number of adhering microspheres in unirradiated tissue remained at the basal level.

CONCLUSIONS

Radiation-induced up-regulation of endothelial cell adhesion molecules may be exploited to target drugs and/or genes to select segments of the endothelium.

Inhibition of gamma-irradiation induced adhesion molecules and NO production by alginate in human endothelial cells

Inflammation is a frequent radiation-induced reaction following therapeutic irradiation. Treatment of human umbilical endothelial cells (HUVEC) with gamma-irradiation (gammaIR) induces the expression of adhesion proteins such as intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin. Since the upregulation of these proteins on endothelial cell surface has been known to be associated with inflammation, interfering with the expression of adhesion molecules is an important therapeutic target. In the present study, we demonstrate that high mannuronic acid-containing alginate (HMA) inhibits gammaIR induced expression of ICAM-1, VCAM-1, and E-selectin on HUVEC in a dose dependent manner. HMA also inhibited gammaIR induced production of Nitric oxide (NO). These data suggest that HMA has therapeutic potential for the treatment of various inflammatory disorder associated with an increase of endothelial leukocyte adhesion molecules.

Effects of UVB radiation on cytokine generation, cell adhesion molecules, and cell activation markers in T-lymphocytes and peripheral blood HPCs

BACKGROUND

Immunomodulatory effects of UV light have increasingly become a focus in transfusion medicine, BMT and transplantation immunology. In the transplant setting, the use of UVB radiation may reduce or abolish T-cell activation without compromising either bone marrow (BM) engraftment or graft-versus-leukemia effect. In this study, BM and apheresis-derived peripheral blood HPCs were used to investigate the effects of UVB on colony-forming ability, CD34+ cell viability, and growth potential, as well as on the secretion of MNC cytokines and the expression of cell surface markers and adhesion molecules.

STUDY DESIGN AND METHODS

After UVB radiation, enriched populations of T cells and antigen-presenting cells (APCs) were treated with PHA, and the MNC response was measured, as was colony-forming ability. CD34+ cells were quantified and their growth potential was determined in culture. Next, T-cell activation status, cell adhesion molecule and cell surface activation marker expression, and cytokine profiles were evaluated, and cytokine mRNA was quantitated. Parallel studies were done in unirradiated control cell populations.

RESULTS

Low-dose (10 mJ/cm(2)) UVB mitigates MNC proliferative responses by 94 percent while maintaining 60 and 80 percent of colony-forming ability in peripheral blood HPC and BM preparations, respectively, and >50 percent of colony-forming ability in CD34+ cell-enriched samples. Low-dose UVB radiation also significantly reduces T-cell production of TNFalpha, TNFalpha mRNA, TNFbeta, IL-2, and IL-6 and downregulates T-cell expression of CD28, CD25, CD69, and intercellular adhesion molecule 1.

CONCLUSION

These findings have shown that a "window" of low-dose UVB radiation (10 mJ/cm(2)) exists, at which BM- and peripheral blood-derived MNC proliferation is inactivated, while the HPCs are relatively spared. UVB light selectively affects T cells, while APCs are resistant to low doses of UVB. UVB radiation also alters the expression of some cell surface markers and cytokines that are important in T-cell activation pathways. Reduction of T-cell activation without cytocidal effect may allow UVB radiation to become an immunomodulating agent in BM or HPC transplantation.

Irradiation induces increase of adhesion molecules and accumulation of beta2-integrin-expressing cells in humans

PURPOSE

The purpose of our investigation was to describe the dose- and time-dependent histomorphologic alterations of the irradiated tissue, the composition of the infiltrate, and the expression patterns of various adhesion molecules.

METHODS AND MATERIALS

We analyzed immunohistochemically alterations in oral mucosa in 13 head and neck cancer patients before radiotherapy and with 30 Gy and 60 Gy. All had oral mucosa irradiation, with a final dose of 60 Gy using conventional fractionation. Snap-frozen specimens were stained using the indirect immunperoxidase technique. Histomorphology was studied in paraffin-embedded sections. In addition, we determined the clinical degree of oral mucositis.

RESULTS

Histomorphologic evaluation showed no vascular damage. Irradiation caused a steep increase of beta2-integrin-bearing cells (p < 0.01), whereas the percentage of beta1-integrin-positive cells remained at low levels. Additionally we found an increase in the expression of endothelial intercellular adhesion molecule-1 (ICAM-1) (p < 0.01) and E-selectin (p < 0.05), while endothelial vascular cell adhesion molecule-1 (VCAM-1) expression remained at very low levels.

CONCLUSION

Our findings indicate that in radiation-induced oral mucositis there is no marked vascular damage until the end of radiotherapy. For recruitment of leukocytes, beta2 is more involved than beta1. Pharmaceuticals that block leukocyte adhesion to E-selectin or ICAM-1 may prevent radiation-mediated inflammation in oral mucosa.

Biology of taste buds and the clinical problem of taste loss

Taste buds are the anatomical structures that mediate the sense of taste. They comprise taste cells and nerve fibers within specialized epithelial structures. Taste cells are traditionally described by histologic methods as basal, dark, intermediate, and light cells, with the nerve fibers surrounding and infiltrating the taste buds. By means of immunohistochemical methods, taste cells and gustatory nerve fibers can be classified in functional groups based on the expression of various cell adhesion molecules and other proteins. When taste buds become damaged, the loss of the ability to taste results. This loss is not uncommon and can impact health and quality of life. Patients who receive radiation therapy for head and neck cancer often experience taste loss, which leads to compromised nutritional intake and a worse outcome than patients who do not experience taste loss. The mode of radiation damage to taste cells and nerve fibers has been investigated using cell adhesion molecules, synaptic vesicle proteins, and other cell markers. The light and intermediate cells are preferentially affected by ionizing radiation, whereas the nerve fibers remain structurally intact. Experimental studies of radiation-induced taste loss are performed via a unique animal/human model.

Adhesion molecule expression in normal skin and melanocytic lesions. Role of UV-irradiation and architectural characteristics in nevi

Cell adhesion between surfaces of cells and to extracellular matrices represents a fundamental mechanism in tissue organization and influences the biological behaviour and the architecture of tumors. We investigated the expression of various adhesion molecules in normal skin (n=5), nevi (n=29), and malignant melanoma (n=10) by immunohistochemistry. Special attention was paid to the correlation between adhesion molecule expression and the respective architectural features, e.g. UV-induced morphological changes, and the arrangement of melanocytes in congenital nevi. In nevi, a single erythemagenic dose of UV-light did not influence the integrin expression of melanocytes, but results in an upregulation of alpha3 beta1- and alpha6 beta1-integrin within the suprabasal layers of the epidermis. This suprabasal labelling was associated with an increased number of suprabasal melanocytes in UV-irradiated nevi which were detected with HMB-45 antibody. Nine of 10 congenital nevi demonstrated a labelling of alpha4 beta1-integrin only in melanocytes of the deeper dermis. This integrin previously has been associated with high tumor thickness and the clinical outcome in melanomas. The integrin profile observed in melanomas differed in part from that seen in nevi with expression of beta2- and beta3-integrins in some cases. The results may indicate a correlation between adhesion molecule expression and histopathological findings in melanocytic lesions.

Comparison of changes in endothelial adhesion molecule expression following UVB irradiation of skin and a human dermal microvascular cell line (HMEC-1)

We have assessed the pattern of dermal endothelial adhesion molecule expression following broadband UVB irradiation in vivo and in vitro. Skin biopsies were taken from 4 human volunteers at baseline and at 4, 8 and 24 h post-irradiation with 2.5 minimal erythema doses of UVB. Sections were stained immunohistochemically for E-selectin, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1). CD31 and neutrophil elastase. The effect of direct UVB irradiation on E-selectin, ICAM-1 and VCAM-1 was examined in a human dermal microvascular endothelial cell line, HMEC-1. Cultured HMEC-1 were irradiated with 2.5-40 mJ/cm2 of UVB, and assessed for adhesion molecule expression by immunofluorescence microscopy and fluorescence-activated cell sorter analysis. In vivo, E-selectin was minimally expressed on EC at baseline and was induced by 4 h following irradiation, P < 0.01. ICAM-1 was moderately expressed at baseline and appeared mildly induced at 24 h, although this did not reach statistical significance. VCAM-1 was weakly expressed in unirradiated skin while CD31 was moderately expressed, but neither was induced by UVB irradiation. A significant neutrophilic infiltrate appeared by 8 h and was maximal at 24 h, P < 0.05. Neutrophil infiltration correlated with E-selectin expression, r = 0.96. In HMEC-1, ICAM-1 was upregulated at 24 h post-irradiation, with an increase in mean channel fluorescence from 100% at baseline to 145 (SD12)% at 24 h, P < 0.05. No change was seen in expression of E-selectin, VCAM-1 or CD31. These studies support the involvement of endothelial adhesion molecules E-selectin and ICAM-1 in UVB-induced inflammation. Whereas ICAM-1 is upregulated by direct irradiation of endothelial cells, E-selectin stimulation appears to be an indirect effect.

Effects of ultraviolet B radiation on cytoskeletal and adhesion molecules in human epidermis

The expression of cytokeratins (CK), various adhesion molecules and growth factor receptors were investigated in ultraviolet (UV) erythemas 24 h and 48 h after exposure to 4 times the minimal erythema dose. Skin biopsies were analysed immunohistochemically using a battery of antibodies and biochemically by gel-electrophoresis. The CK pattern was shown to change within 24 h. CK typical of basal keratinocytes were detectable heterogeneously within the suprabasal compartment, and the staining for suprabasal CK was heterogeneous in prickle cells. Interestingly, CK 17, not detectable in normal epidermis, was induced within a few hours in suprabasal cells but not in basal ones. In addition, CK 6 and 16, typical for hyperproliferation, were intensively synthesized in all epidermal layers already 24 h after UV exposure. Moreover, integrin expression was studied and surprisingly integrins were heterogeneously detectable, the staining being patchy in suprabasal keratinocytes and reduced within the basal layer. Receptors of epidermal growth factor and nerve growth factor were distributed in UV erythema very irregularly and weakly. Our findings argue for profound changes in composition of cytoskeleton and of cell adhesion molecules in the epidermis shortly after UV exposure.

Doses of Ultraviolet Radiation that Modulate Accessory Cell Activity and ICAM-1 Expression Are Ultimately Cytotoxic for Murine Epidermal Langerhans Cells

Mechanisms that underlie immunomodulatory properties of ultraviolet (UV) radiation remain incompletely characterized. Recently, we have studied effects of UV on the functional activity of epidermal Langerhans cells (LC) and have attempted to relate inhibitory effects of UV on LC function to modulatory effects of UV on adhesion molecule expression by LC. Exposure of LC in vitro to amounts of UVB, UVC, or psoralen+UVA (PUVA) radiation that inhibited LC function also prevented increased expression of intercellular adhesion molecule-1 by LC in vitro. Subsequent studies revealed that amounts of UV radiation that inhibited LC function and modulated ICAM-1 expression also decreased LC survival in vitro, although UV-induced LC cytotoxicity did not become apparent until 48-72 h after UV exposure. Our results are consistent with those of previous studies that suggested that low doses of UV radiation were cytotoxic for LC in situ. The potential cytotoxicity of UV radiation for LC should be considered when studies of effects of UV radiation on immune responses in skin are interpreted.