Biomedical subjects

R M Lovis

Publications and source records attributed to R M Lovis.

4 recordsLinked to original sources

PubMed1996

Autocrine regulation of collagenase gene expression by TNF-alpha in U937 cells.

Tumor necrosis factor alpha (TNF-alpha) has been shown to induce the production of interstitial collagenase by fibroblasts and chondrocytes. We investigated the role of TNF-alpha in collagenase gene expression by U937 monocyte/macrophage cells. Transcription of the TNF-alpha gene was observed after 0.5 h of phorbol myristate acetate (PMA) stimulation. Collagenase mRNA expression was not observed until 5-7 h of activation with PMA. TNF-alpha was detected in the culture supernatants 2-3 h before transcription of the collagenase gene. Neutralization of TNF-alpha protein with anti-TNF-alpha antibodies significantly reduced collagenase mRNA expression. Protein kinase C (PKC) and protein tyrosine kinase (PTK) inhibition essentially abolished both PMA-induced TNF-alpha protein secretion and collagenase mRNA expression. Collagenase gene expression induced by exogenous TNF-alpha in U937 cells stimulated with a suboptimal concentration of PMA was suppressed by PTK, but not PKC, inhibition. The pyrrolidine derivative of dithiocarbamate, a potent inhibitor of nuclear factor-kappa B (NF-kappa B) activation, resulted in a marked reduction in collagenase gene transcription, however, no reduction of TNF-alpha secretion was noted. Anti-TNF-alpha antibodies inhibited PMA-induced NF-kappa B activation. These observations demonstrate an important role for TNF-alpha in the autocrine regulation of collagenase gene expression by U937 cells. Additionally, TNF-alpha-induced PTK and NF-kappa B activation were important in collagenase gene expression in this cell line.

Antibodies↗

PubMed1994

Soluble intercellular adhesion molecule-1 in arthritis.

The objective of this study is to determine whether soluble intercellular adhesion molecule-1 (sICAM-1) 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 immunoabsorbent 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.

Adult↗

PubMed1992

Activation of synovial fluid T lymphocytes by 60-kd heat-shock proteins in patients with inflammatory synovitis.

OBJECTIVE: Synovial fluid lymphocytes from patients with rheumatoid arthritis and with other forms of inflammatory synovitis demonstrate enhanced proliferative responses to Mycobacterium tuberculosis antigens, in particular, the 65-kd heat-shock protein. There is a high degree of homology between the human and the mycobacterial 60-kd family of heat-shock proteins. These studies were performed to determine if the enhanced response to the mycobacterial 65-kd heat-shock protein was due to cross-reactivity of an immune response generated against the human homolog. METHODS: These studies were performed by in vitro culture of isolated synovial fluid mononuclear cells with crude and purified antigens. RESULTS: The synovial fluid lymphocytes of a majority of patients with rheumatoid arthritis recognized the mycobacterial 65-kd heat-shock protein, as evidenced by T cell proliferation. In contrast, only 18% of all samples tested responded to a highly purified recombinant human 60-kd heat-shock protein. With only one exception, proliferative responses to the mycobacterial antigen were stronger than those to the human homolog. The proliferative responses generated against mycobacterial 65-kd heat-shock proteins from different sources were highly correlated. CONCLUSION: The findings suggest that the enhanced proliferative response to the mycobacterial 65-kd heat-shock protein noted in most patients with rheumatoid arthritis and other forms of inflammatory synovitis is not due to cross-reactivity of an immune response directed against the human heat-shock protein.

Antigens, Bacterial↗

PubMed1992

Ultrastructural characteristics of the spleen in hairy cell leukemia.

Eighteen spleens derived from patients with hairy cell leukemia (HCL) were analyzed by correlative scanning and transmission electron microscopy. In 15 of the cases, the white pulp areas were markedly decreased or absent when compared to normal spleens, although few hairy cells were observed within this region. In only one case did the white pulp appear normal. In all HCL cases, hairy cells were observed within normal, dilated, and abnormal sinuses. The abnormal sinuses contained hairy cells of typical morphology attached to other hairy cells, to endothelial lining, and to erythrocytes. The degree of sinus filling by hairy cells varied from loosely- to tightly-packed. Endothelial cells exhibiting degenerative changes, such as swelling with smooth surfaces and dilated intercellular spaces, were frequently seen. These results indicate that in addition to the previously described overcrowding of the spleen by hairy cells, the splenic tissue itself is considerably altered and sometimes severely damaged in patients with HCL.

Humans↗