Source: Heart  |  Posted 8 years ago

Intramuscular gold treatment in patients with rheumatoid arthritis stimulates cytokine production, and its mode of action may be mediated through IL-10 production, according to a recent Swedish study.

Intramuscular gold in the form of gold sodium thiomalate (GSTM) is a common treatment for rheumatoid arthritis. Its mode of action is unknown, but it has traditionally been thought to act as an immunosuppressant.

Recent []in vitro[] studies have shown that GSTM can stimulate the production of two cytokines, specifically interleukin-6 (IL-6) and interleukin-10 (IL-10), in monocytes. This suggests that the effects of GSTM may actually be immunostimulatory. Clinical studies, however, have yet to be performed.

Sofia Ernestam and colleagues at the Huddinge University Hospital, Karolinska Institute, Stockholm, Sweden, analysed cytokine production during GSTM treatment in patients with rheumatoid arthritis.

The study included 20 patients with rheumatoid arthritis who were treated with GSTM for 3 months. Peripheral blood mononuclear cells (PBMC) were collected from each patient at start of study, week 4, and week 12. IL-6, IL-10, and interferon-g (IFN-g) were measured from PBMC and serum samples. Cytokine production was also assayed in PBMCs collected at baseline that were stimulated []in vitro[] with increasing concentrations of GSTM (0, 3, 12.5, 40 ?g/ml). Disease activity was measured at baseline, 12, 20, and 28 weeks.

After 4 weeks of GSTM treatment, the number of IL-10, IL-6, and IFN-g producing cells significantly increased from baseline numbers. Furthermore, IL-6 producing cells maintained their increase over baseline at 12 weeks. In contrast, while serum levels of IL-10 showed an increase at 4 weeks, the serum levels of IL-6 remained unchanged from baseline values.

Interestingly, []in vitro[] stimulation of PBMCs with GSTM increased IL-10 production, which correlated with development of skin reactions during treatment. More specifically, patients whose baseline PBMCs showed high gold induced IL-10 production also had a lower incidence of skin reactions.

Overall, an association between clinical response and cytokine production was not evident, as determined by disease activity measurements.

The authors conclude that "this study indicates an immunostimulatory effect of GSTM treatment in patients with rheumatoid arthritis." They further suggest that "the increase in IL-10 production during GSTM treatment may contribute to the positive effects of gold in rheumatoid arthritis."