Dichloroacetate alleviates development of collagen II-induced arthritis in female DBA/1 mice

Abstract

Introduction: Dichloroacetate (DCA) has been in clinical use for the treatment of lactacidosis and inherited mitochondrial disorders. It has potent anti-tumor effects both in vivo and in vitro, facilitating apoptosis and inhibiting proliferation. The pro-apoptotic and anti-proliferative properties of DCA prompted us to investigate the effects of this compound in arthritis.

Methods: In the present study, we used DCA to treat murine collagen type II (CII)-induced arthritis (CIA), an experimental model of rheumatoid arthritis. DBA/1 mice were treated with DCA given in drinking water.

Results: Mice treated with DCA displayed much slower onset of CIA and significantly lower severity (P < 0.0001) and much lower frequency (36% in DCA group vs. 86% in control group) of arthritis. Also, cartilage and joint destruction was significantly decreased following DCA treatment (P = 0.005). Moreover, DCA prevented arthritis-induced cortical bone mineral loss. This clinical picture was also reflected by lower levels of anti-CII antibodies in DCA-treated versus control mice, indicating that DCA affected the humoral response. In contrast, DCA had no effect on T cell- or granulocyte-mediated responses. The beneficial effect of DCA was present in female DBA/1 mice only. This was due in part to the effect of estrogen, since ovariectomized mice did not benefit from DCA treatment to the same extent as sham-operated controls (day 30, 38.7% of ovarectomized mice had arthritis vs. only 3.4% in sham-operated group).

Conclusion: Our results indicate that DCA delays the onset and alleviates the progression of CIA in an estrogen-dependent manner.

Figure 1

Frequency, severity of arthritis, bone destruction, and weight change in collagen II (CII)-induced arthritis mice treated with dichloroacetate (DCA) (3 mg/mouse per day) or water. (a) DCA effect on frequency of arthritis in both female and male CII arthritis mice. (b) DCA treatment on both female and male mice in regard to severity of arthritis. (c) Synovitis and bone erosion in CII-immunized DBA/1 with or without DCA treatment. (d) Weight change in DCA-treated mice and water controls during the course of CII-induced arthritis experiments. Values from three independent experiments were pooled. The DCA-treated group and the water-drinking group each contained 22 mice.

Figure 2

Micrographs of tarsal joints from collagen II-immunized female and male DBA/1 mice. (a) Representative image of a tarsal joint from a female water-drinking mouse. (b) Representative image of a tarsal joint from a female dichloroacetate (DCA)-drinking mouse (3 mg DCA/mouse per day). (c) Representative image of a tarsal joint from a male water-drinking mouse. (d) Representative image of a tarsal joint from a male DCA-drinking mouse (3 mg DCA/day). Arrowheads indicate erosion of bone and cartilage. Scale bar = 100 μm. B: bone; C: cartilage; JC: joint cavity; S: synovitis.

Figure 3

Dichloroacetate (DCA) impact on in vivo inflammatory immune response. (a) IgG anti-collagen II antibody levels from the DCA-drinking group and the water-drinking group. (b) Serum pro-inflammatory cytokine intereukin-6 (IL-6) levels from DCA-drinking mice and water controls. Values from two experiments were pooled. The DCA-drinking group and the water-drinking group each contained 14 mice. OD: optical density.

Figure 4

Dichloroacetate (DCA) effect on bone mineral density (BMD) (female mice only). (a) Cortical bone mineral content in mice treated with DCA or water. (b) The thickness of cortical bone in the DCA-drinking group and the water-drinking group. (c) Cortical bone area in the DCA-drinking group and the water-drinking group. (d) Total BMD measured in the DCA group and water controls. (e) Trabecular BMD in the DCA-treated group and water controls. One experiment was performed with eight female mice in the DCA-drinking group and eight female mice in the control group.

Figure 5

Impact of ovariectomy (OVX) on dichloroacetate (DCA) treatment of arthritis. Frequency (a) and severity (b) of arthritis in DCA-treated ovariectomized mice and in sham-operated mice treated with DCA. (c) Histological index of OVX and sham-operated mice treated with DCA. Results of two experiments were pooled with 31 OVX mice and 29 sham-operated mice.