Gold causes genetically determined autoimmune and immunostimulatory responses in mice

Abstract

Natrium aurothiomaleate (GSTM) is a useful disease-modifying anti-rheumatic drug, but causes a variety of immune-mediated adverse effects in many patients. A murine model was used to study further the interaction of GSTM with the immune system, including induction of systemic autoimmunity. Mice were given weekly intramuscular injections of GSTM and controls equimolar amounts of sodium thiomaleate. The effects of gold on lymphocyte subpopulations were determined by flow cytometry. Humoral autoimmunity was measured by indirect immunofluorescence and immunoblotting, and deposition of immunoglobulin and C3 used to assess immunopathology. Gold, in the form of GSTM, stimulated the murine immune system causing strain-dependent lymphoproliferation and autoimmunity, including a major histocompatibility complex (MHC)-restricted autoantibody response against the nucleolar protein fibrillarin. GSTM did not cause glomerular or vessel wall IgG deposits. However, it did elicit a strong B cell-stimulating effect, including both T helper 1 (Th1)- and Th2-dependent isotypes. All these effects on the immune system were dependent on the MHC genotype, emphasizing the clinical observations of a strong genetic linkage for the major adverse immune reactions seen with GSTM treatment.

Fig. 1

Serum from an A.SW mouse treated with natrium aurothiomaleate (GSTM) for 12 weeks incubated on HEp-2 cells, followed by incubation with fluorescein isothiocyanate (FITC)-conjugated anti-mouse IgG antibodies. Strong nucleolar staining with nuclear dots.

Fig. 2

Serum from an A.TH mouse treated with natrium aurothiomaleate (GSTM) for 12 weeks incubated on HEp-2 cells, followed by incubation with fluorescein isothiocyanate (FITC)-conjugated anti-mouse IgG antibodies. Combined speckled, nucleolar and nucleoplasmic staining.

Fig. 3

Immunoblotting of sera using sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS-PAGE) separated mouse liver nuclei. Lane 1: molecular weight markers (kDa). Lane 2: human reference serum blotting the 34-kDa protein fibrillarin (arrow). Lanes 3–4 and 5–6: anti-nuclear antibody (ANA)-negative SJL and A.SW mice treated with sodium thiomaleate (TM) for 12 weeks, respectively. No blotting. Lanes 7–12 and 13–15: anti-nucleolar antibodies (ANoA)-positive SJL and A.SW mice, respectively, treated with natrium aurothiomaleate (GSTM) for 12 weeks, respectively. Strong blotting of a 34-kDa protein. Lane 16: A.TH mouse treated with GSTM for 12 weeks showing a combined speckled, nucleoplasmic and nucleolar ANA pattern. Multiple staining bands (see Results). Lane 17: A.TH mouse treated with GSTM for 12 weeks showing a strong nucleolar staining. Blotting of a 34-kDa protein. Lane 18: A.TH mouse treated with TM for 12 weeks, ANA-negative. No blotting.