Search PubMed⌕ Search

Biomedical subjects

D T Graves

Publications and source records attributed to D T Graves.

At least 73 records · Page 4Linked to original sources
PubMed1993

Expression of monocyte chemoattractant protein 1 in human inflamed gingival tissues.

Gingival inflammation is initiated by bacterial colonization on the tooth surface. It is characterized by infiltration of mononuclear cells, a common feature of many forms of chronic inflammation. Monocyte chemoattractant protein 1 (MCP-1) is the predominant monocyte chemoattractant secreted by a variety of different cells in vitro. For this report, we examined MCP-1 expression in bacterially induced gingival inflammation by immunohistochemistry and in situ hybridization. The cell types expressing MCP-1 are identified as vascular endothelial cells and monocytes/macrophages. Correlation analysis shows that the number of cells expressing MCP-1 is related to the degree of inflammation. Our finding that MCP-1 is expressed in inflamed gingival tissue suggests that MCP-1 plays an important role in the recruitment of monocytes and amplification of inflammatory signals in bacterially induced inflammation.

Adult↗
PubMed1992

Elevated expression of monocyte chemoattractant protein 1 by vascular smooth muscle cells in hypercholesterolemic primates.

Atherosclerosis is marked by an overt inflammatory infiltrate, with enhanced recruitment of monocytes/macrophages observed in both human and experimental atherosclerosis. We previously determined that monocyte chemoattractant protein 1 (MCP-1) accounts for virtually all of the chemotactic activity produced by vascular (aortic) smooth muscle cells in culture. We now report that arteries from a primate model of atherosclerosis with dietary-induced hypercholesterolemia exhibit increased levels of MCP-1 mRNA expression in vivo, whereas their normal counterparts demonstrate minimal MCP-1 expression. Furthermore, immunohistochemistry and in situ hybridization clearly indicate that the expression of MCP-1 protein and mRNA is in the smooth muscle cells of the medial layer of the artery and in monocyte-like and smooth muscle-like cells found in the overlying intimal lesion. These studies indicate that one of the responses to dietary hypercholesterolemia is the expression of MCP-1 by vascular smooth muscle cells. This expression, when augmented with other cellular and molecular factors, could significantly contribute to the recruitment of monocytes/macrophages to the vessel wall.

Animals↗
PubMed1992

Expression of monocyte chemoattractant protein 1 mRNA in human idiopathic pulmonary fibrosis.

Macrophages are thought to play an important role in the pathologic changes associated with idiopathic pulmonary fibrosis (IPF). The mechanisms for increased monocyte/macrophage recruitment in IPF are unknown. Monocyte chemoattractant protein 1 (MCP-1) is the predominant monocyte chemoattractant secreted by a variety of different cell types in culture. We examined the expression of MCP-1 mRNA and its protein product in vivo in IPF and non-IPF lung specimens by in situ hybridization and immunocytochemistry. The cell types expressing MCP-1 in vivo were identified by immunostaining with specific antibodies. We demonstrated the expression of MCP-1 mRNA in pulmonary epithelial cells, in monocytes/macrophages, and in vascular endothelial and smooth muscle cells. Lung epithelial cells in patients with IPF strongly expressed MCP-1 mRNA and its protein product. In contrast, epithelial cells in non-IPF specimens did not express MCP-1 mRNA. Macrophages and vascular endothelial and smooth muscle cells were shown to express MCP-1 in both IPF and non-IPF lung specimens. These findings provide a basis for the understanding of the in vivo physiologic processes that mediate monocyte/macrophage recruitment and infiltration in the lung interstitium and the pathologic state contributing to an increased alveolar monocyte/macrophage population and inflammation in IPF.

Arteries↗
PubMed1992

Monocyte chemoattractant protein-1 regulates adhesion molecule expression and cytokine production in human monocytes.

Monocytes play a critical role in defending the host against foreign organisms and in regulating the behavior of other cells. Monocytes circulate as nonadherent cells in the blood and migrate as adherent cells through tissues. Adhesion molecules mediate not only cell adhesion, but also migration, phagocytosis, and many other adhesion-dependent functions. Monocyte chemoattractant protein-1 (MCP-1) is thought to be responsible for monocyte recruitment in acute inflammatory conditions and may be an important mediator in chronic inflammation. In this study, immunofluorescence flow cytometry was used to determine whether MCP-1 can regulate the cell surface expression of adhesion molecules, particularly beta-2 and alpha-4 integrins and the leukocyte adhesion molecule-1. We found that MCP-1 induced expression of CD11c (p150,95 alpha-subunit) and CD11b (Mac-1 alpha-subunit), and caused little or no change of CD11a (lymphocyte function-associated Ag-1 alpha-subunit), very late activation Ag-4, or leukocyte adhesion molecule-1. We demonstrated that antibodies to beta-2 and alpha-4 integrins inhibited MCP-1-induced monocyte chemotaxis. We also showed that MCP-1 is capable of inducing IL-1 and IL-6, but not TNF production of monocytes. These results indicate that MCP-1 is not only a chemoattractant but also a novel cytokine with the capacity to regulate several parameters of monocyte function.

Antigens, CD↗
PubMed1992

Regulated expression of monocyte chemoattractant protein-1 in normal human osteoblastic cells.

An influx of monocytes is observed in many different physiological and pathophysiological states, including bone remodeling and injury. These cells appear at early stages of bone formation and repair and persist throughout the later stages. In experiments described here, unstimulated normal human osteoblastic cells did not produce detectable levels of monocyte chemotactic activity. However, interleukin-1 (IL-1)-stimulated normal human osteoblastic cells produced a chemoattractant that is similar to monocyte chemoattractant protein-1 (MCP-1) at the levels of mRNA expression, protein production, and chemotactic activity. Northern blot analysis indicates that IL-1 elicits a dose-dependent increase in MCP-1 mRNA in normal human osteoblastic cells. Two proteins of M(r) 9,000 and M(r) 13,000 were specifically immunoprecipitated with MCP-1 antiserum from IL-1-stimulated normal human osteoblastic cells. Monocyte chemotactic activity from IL-1-treated cells was blocked by MCP-1 antiserum. These studies establish that normal human osteoblastic cells can be induced to produce monocyte chemoattractants and that this is accounted for by the induced expression of MCP-1.

Blood Platelets↗
PubMed1992

Expression of monocyte chemotactic protein-1 in human melanoma in vivo.

A common feature of human melanoma is infiltration by monocytes at early stages of tumorigenesis. This infiltration may be highly significant since macrophages have the capacity to alter the behavior of tumor cells. The authors previously demonstrated that the predominant monocyte chemoattractant produced by tumor cells in vitro was monocyte chemotactic protein-1 (MCP-1). The authors identify the expression of MCP-1 in pathologic specimens of both primary and metastatic human melanoma but not in normal skin. The finding that MCP-1 is produced by malignant melanoma suggests that specific genes are expressed in tumor cells that can induce the recruitment of monocytes in vivo.

Cell Movement↗
PubMed1991

Initial characterization of the carbohydrate structure of MCP-1.

MCP-1 is the principle monocyte chemoattractant produced by tumor cells in vitro. We previously identified different isoforms of MCP-1. Here we report that two predominant isoforms of MCP-1 (13 kD and 9 kD) can be distinguished by lectin binding. The results indicate that the disaccharide galactose-beta 1-3D-N-acetyl galactosamine is present on the 13 kD MCP-1 isoform but not the 9 kD isoform. Glycosylation of the 13 kD MCP-1 isoform does not appear to significantly change its antigenic properties and also does not affect its capacity to induce monocyte migration.

Carbohydrate Sequence↗
PubMed1991

Characterization of monocyte chemotactic protein-1 binding to human monocytes.

Monocyte chemotactic protein-1 (MCP-1) stimulates chemotaxis of peripheral blood monocytes. In order to understand the biologic basis of this specific activity, binding studies of 125I-MCP-1 were undertaken. MCP-1 showed saturable binding to monocytes. Scatchard analysis of the monocyte binding data indicate that there are approximately 1,600 high affinity binding sites per monocyte with a Kd = 1.1 nM. Studies with synthetic peptides constructed according to the MCP-1 amino acid sequence indicate that a synthetic peptide, MCP-1[13-35], stimulates monocyte migration and competes with native MCP-1 for binding sites. Inhibition of MCP-1 binding was tested with chemotactic connective tissue proteins. No inhibition of MCP-1 binding was observed with either collagen, elastin-derived peptides or fibronectin. These results identify a single class of unique high affinity MCP-1 binding sites that are likely to recognize a peptide domain on MCP-1 which include the amino acids within the region, 13-35.

Animals↗
PubMed1991

Monocyte chemotactic proteins from human tumor cells.

The production of the monocyte chemoattractant MCP-1 suggests a common mechanism for the recruitment of monocytes/macrophages and provides an explanation for monocyte/macrophage infiltration frequently observed in solid tumors. The regulated production of MCP-1 by non-transformed cells further substantiates the suggestion that MCP-1 is an important inflammatory mediator and is involved in the recruitment of monocytes in a number of pathologic or physiologic conditions.

Animals↗
PubMed1991

Human osteoblasts synthesize and respond to platelet-derived growth factor.

Platelet-derived growth factor (PDGF) is a potent mitogen for cells of mesenchymal origin. We previously demonstrated that PDGF is produced by osteogenic sarcoma cells. We report here that normal human bone-derived cells produce PDGF and that these cells have an osteoblastic phenotype. This was demonstrated by use of a double immunofluorescent technique and by examining cloned human adult osteoblasts. Northern blot analysis indicates that PDGF production is accounted for by expression of the PDGF-A gene. PDGF-AA and PDGF-BB generally stimulated thymidine incorporation in normal human bone explants to a similar extent. All of the cloned human osteoblasts responded to PDGF-BB while the response to PDGF-AA varied. Similarly, five cloned osteoblastic cell populations were shown to produce PDGF while one did not. This result supports the hypothesis that there are different osteoblastic cell populations that differ in their growth factor responses or in the production of growth factors. Our results suggest that PDGF-BB has the potential to act as a paracrine factor for normal human osteoblasts because all of the osteoblastic cell populations responded to PDGF-BB. None of the osteoblastic cell populations expressed the PDGF-B gene, indicating that it would not act as an autocrine factor. Although not definitive, our results suggest that PDGF-AA has the potential to act as an autocrine factor because osteoblastic bone cell populations were shown to express the PDGF-A gene and respond to PDGF-AA.

Blotting, Northern↗
PubMed1991

High-affinity binding of PDGF-AA and PDGF-BB to normal human osteoblastic cells and modulation by interleukin-1.

Bone has the capacity for repair and regeneration. The repair process is thought to be locally regulated by growth factors. One of the growth factors that potentially plays a significant role in these processes is platelet-derived growth factor (PDGF). Two different PDGF genes have been identified, PDGF-A and PDGF-B, whose gene products give rise to biologically active dimers. We now report that PDGF-AA and PDGF-BB exhibit saturable binding to normal human osteoblastic cells. By Scatchard analysis we estimate that there are approximately 43,000 PDGF-AA binding sites per cell, with a dissociation constant (Kd) of 2.2 x 10(-10)M, and 55,000 high-affinity PDGF-BB binding sites per cell, with a Kd of 1.2 x 10(-10)M. The functional consequence of PDGF binding was also assessed. PDGF-AA and PDGF-BB both stimulated migration of normal human osteoblastic cells and stimulated thymidine incorporation. To gain insight into potential transmodulation of the PDGF response, we investigated the capacity of interleukin-1 beta (IL-1 beta), a cytokine that induces bone resorption, to modulate PDGF binding and PDGF-induced biological activity. IL-1 beta significantly reduced PDGF-AA binding and significantly decreased both PDGF-AA-mediated cell migration and thymidine incorporation. In contrast, IL-1 beta had only a small effect of PDGF-BB binding and PDGF-BB-induced biological activity in normal human osteoblastic cells.

Adolescent↗
PubMed1991

Biologically active mediators: platelet-derived growth factor, monocyte chemoattractant protein-1, and transforming growth factor-beta.

The advent of tissue culture techniques provided efficient means to measure the activities of hormones that act at very low concentrations. By following a specific activity, biologically active mediators could then be efficiently purified from impure starting materials. Different assay systems allowed the purification of different types of factors. Growth-inducing factors, such as platelet-derived growth factor, were discovered because they could stimulate DNA synthesis in vitro. Chemotactic factors, such as monocyte chemoattractant protein-1, were discovered based on their capacity to stimulate migration of cells in vitro. Transforming growth factors were originally described because of their capacity to stimulate the growth of nontransformed cells in soft agar. This review describes the effects of biologically active mediators using platelet-derived growth factor, monocyte chemoattractant protein-1, and transforming growth factor-beta as examples.

Animals↗
PubMed1990

Post-translational modification of a monocyte-specific chemoattractant synthesized by glioma, osteosarcoma, and vascular smooth muscle cells.

Chemotaxis is an important step in monocyte recruitment in inflammation, wound healing, and tumor growth. We reported previously that monocyte chemotactic activity secreted by malignant cells and normal smooth muscle cells is associated with a protein or family of proteins that are related to the monocyte-specific smooth muscle cell-derived chemotactic factor (SMC-CF) (Graves, D. T., Jiang, Y. L., Williamson, M. J., and Valente, A. J. (1989) Science 245, 1490-1493). Similar monocyte chemotactic proteins (MCP-1) produced by U-105MG human glioma cells have also been identified (Yoshimura, T., Robinson, E. A., Tanaka, S., Appella, E., Kuratsu, J., and Leonard, E. J. (1989) J. Exp. Med. 169, 1449-1459). We now report that the MCP-1 gene is expressed in MG-63 human osteosarcoma and vascular smooth muscle cells and that SMC-CF antiserum specifically immunoprecipitates proteins synthesized by U-105MG glioma cells. Experiments were undertaken to elucidate the processing pathway of MCP-1/SMC-CF-like proteins in each of these cell types. These experiments demonstrate that larger MCP-1/SMC-CF-like proteins are derived from a Mr = 9000 precursor. Post-translational modification involves the addition of O-linked carbohydrates and sialic acid residues. Differences in carbohydrate processing account for the heterogeneity in MCP-1/SMC-CF-like proteins produced by different cell types. Secretion of these proteins occurs rapidly following processing events in the endoplasmic reticulum-Golgi compartment.

Blotting, Northern↗
PubMed1990

Expression of transferrin and vitamin D-binding protein genes in an osteogenic sarcoma cell line.

Expression of genes encoding transferrin and the vitamin D-binding protein is described in a cell line, U-2 OS, derived from a human osteogenic sarcoma. The mRNA transcripts of transferrin and vitamin D-binding protein were shown to be the lengths of those found in normal human liver. The cells synthesize and secrete the transferrin and vitamin D-binding proteins, in addition to human albumin and ceruloplasmin. The U-2 OS cells were successfully transfected with chimeric genes carrying 670 bp of the 5' regulatory sequence of the human transferrin gene fused to a reporter chloramphenicol acetyltransferase gene. These data indicate that the appropriate transcriptional factors required for expression of four plasma proteins are produced by U-2 OS nuclei and that the U-2 OS cell line will be useful for studies analyzing regulation of these genes.

Ceruloplasmin↗
PubMed1989

Identification of monocyte chemotactic activity produced by malignant cells.

Human malignant cells secrete low molecular size proteins that attract peripheral blood monocytes and may be responsible for the accumulation of tumor-associated macrophages observed in vivo. Similar chemotactic proteins are secreted by cultured vascular smooth muscle cells. The predominant monocyte chemoattractants produced by tumor cells of differing origin were demonstrated to be related to smooth muscle cell-derived chemotactic factor. Thus, a single class of chemotactic proteins is produced by different cell types, which suggests a common mechanism for the recruitment of monocytes and macrophages. These results are significant in view of the potential of macrophages to affect tumor growth.

Animals↗
PubMed1989

Platelet-derived growth factor is not chemotactic for human peripheral blood monocytes.

PDGF is a mitogenic protein stored in platelets and released upon platelet degranulation. Recent evidence indicates that PDGF plays an important role in both physiologic and pathophysiologic processes, particularly in tumorigenesis, wound healing, pulmonary fibrosis, and atherogenesis. In addition to its mitogenic potential, it has been reported that PDGF stimulates monocyte chemotaxis. Since the recruitment of monocytes from the peripheral vasculature is an important event in vivo, the potential role of PDGF as a monocyte chemoattractant has significant biologic implications. However, we now report that homogeneous human PDGF from platelets and a recombinant PDGF-2 homodimer do not stimulate monocyte chemotaxis. In contrast to previous reports these results indicate that PDGF is not a monocyte chemoattractant.

Cell Line↗
PubMed1989

Study of the growth factor requirements of human bone-derived cells: a comparison with human fibroblasts.

Recent techniques have been devised for the culture of bone cells derived from human bone explants. These cells, which are thought to represent several stages in the osteoblast lineage, respond to PTH with an increase in cyclic AMP content, and have high basal alkaline phosphatase activity which is increased on exposure to 1,25-dihydroxyvitamin D3 and decreased by PTH. Such characteristics distinguish these cells from fibroblasts. In this study, we demonstrate that human bone-derived cells also differ from fibroblasts in their growth characteristics. Bone-derived cells proliferated in basal medium supplemented with platelet-poor plasma. The rate of proliferation was enhanced by additional supplementation with platelet-derived growth factor (PDGF), and further increased when a combination of growth factors was added (PDGF, TGF-beta and EGF). In contrast, fibroblasts did not proliferate in basal medium supplemented with platelet-poor plasma and the addition of PDGF alone stimulated fibroblast proliferation to the same extent as 10% fetal bovine serum. Supplementation with other growth factors did not further enhance the response of fibroblasts to PDGF. These results emphasize the differences in proliferative responses between human bone-derived cells and human fibroblasts, and indicate that the factors responsible for osseous regeneration in vivo may differ from those factors which regulate repair of soft tissue wounds.

Bone and Bones↗