Date of Award

1980

Degree Type

Dissertation

Degree Name

Doctor of Philosophy in Pharmaceutical Sciences

Specialization

Pharmacy and Toxicology

First Advisor

George C. Fuller

Abstract

Gold sodium thiomalate (GST) effects on cultured rheumatoid synovial cells were used as a model to investigate a mechanism which can explain clinical benefits gained by patients from gold therapy. Synovial tissue obtained from patients with rheumatoid arthritis who were undergoing reconstructive joint surgery was used to obtain explant culture of synovial cells. The experiments described were performed on growing monolayer cultures during the second to fifth passages. Synovial cells were exposed to GST at pharmacologically relevant concentrations (10-100 uM). Vacuoles were found by phase contrast microscopy in synovial cells in culture after 2 days of exposure to 100 uM GST. The vacuoles, aurosomes, were found to contain electron dense material by electron microscopy that contained gold as identified by X-ray probe analysis. The structure of the aurosomes, electron dense lamellae structures in membrane bound vesicles, was found to be similar to those found in synovial tissue of patients with rheumatoid arthritis who had received gold therapy. The time course for gold accumulation in the cell layer paralleled with aurosome formation and the degree of inhibition of [3H]thymidine incorporation into DNA. DNA synthesis, DNA content and cell number were decreased in a dose dependent manner after synovial cells were exposed to GST containing medium. The synthesis of medium proteins per flask by synovial cells was decreased in a dose dependent manner with collagen decreased to a greater extent. The percentage of collagen to total protein synthesized by synovial cells was decreased in a dose dependent manner. A biphasic response of an increase followed by a decrease of proteins synthesized per cell or per DNA unit was found due to GST exposure. The increase in collagen protein per cell was found to be predominantly type I collagen. The percentage of type III collagen decreased due to synovial cells exposure to GST containing medium. Removal of GST from the medium resulted in recovery of biochemical parameters at low concentrations and a partial recovery at high concentration. Neither aurosomes nor gold could be completely removed from synovial cells after medium changes and subculturing. An important therapeutic mechanism of action of gold in the treatment of patients with rheumatoid arthritis may be by directly inhibiting synovial cells proliferation and altering protein synthesis by synovial cells to a nonconducive matrix for pannus expansion.

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