The peroxisome proliferator-activated receptor gamma agonist rosiglitazone ameliorates murine lupus by induction of adiponectin

Abstract

Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease for which current therapy is suboptimal. SLE is characterized by autoantibody production, with renal disease and premature atherosclerosis being common and severe manifestations causing appreciable morbidity and mortality. Peroxisome proliferator-activated receptor gamma (PPARgamma) agonists are widely used in the treatment of diabetes mellitus for their insulin-sensitizing properties, but also have immunomodulatory effects. In this report, we show that the PPARgamma agonist rosiglitazone reduces autoantibody production, renal disease, and atherosclerosis in mouse models of SLE. The beneficial effect of rosiglitazone on SLE manifestations depends on the induction of adiponectin, because rosiglitazone has no effect on autoantibody production or renal disease in lupus mice that lack adiponectin. In addition, lupus mice that lack adiponectin develop more severe disease than adiponectin-sufficient lupus mice, indicating that endogenous adiponectin is involved in regulating disease activity. Furthermore, administration of exogenous adiponectin ameliorates disease. These experiments suggest that PPARgamma agonists may be useful agents for the treatment of SLE. They also demonstrate that induction of adiponectin is a major mechanism underlying the immunomodulatory effects of PPARgamma agonists.

FIGURE 1

Gld.apoE^−/− mice treated with rosiglitazone have less severe disease. Gld.apoE^−/− mice were maintained on normal diet (n = 9, 4 male and 5 female) or rosiglitazone-supplemented normal diet (n = 9, 4 male and 5 female) for 12 wk, starting at 7 wk of age, and disease parameters were measured at 19 wk of age. A, Body weight did not differ between experimental groups throughout the duration of the study. B, Rosiglitazone treatment resulted in a significant decrease in spleen weight but had no effect on lymph node weight (C). D, Serum ANA titers were measured by immunofluorescence on HEp2 slides. E, Representative kidney sections showing a decrease in glomerular size and cellularity with rosiglitazone treatment. F, Quantification of glomerular tuft area and G, glomerular cell count. H, Representative examples of aortic atherosclerosis detected using en face Oil Red O staining. I, Quantification of atherosclerosis lesion area. *, p < 0.05; **, p < 0.01; ***, p < 0.001 vs normal diet.

FIGURE 2

Adiponectin administration decreases disease in gld.apoE^−/− mice. A, Gld.apoE^−/− mice shown in Fig. 1 were maintained on normal diet (n = 9, 4 male and 5 female) or rosiglitazone-supplemented normal diet (n = 9, 4 male and 5 female) for 12 wk, starting at 7 wk of age, and serum adiponectin levels were measured at 19 wk of age. B–D, Gld.apoE^−/− mice were treated for 2 wk with an adenoviral vector expressing β-galactosidase (Ad-βgal) (n = 5, 2 male and 3 female) or with an adenoviral vector expressing full-length mouse adiponectin (Ad-Apn) (n = 4, 2 male and 2 female) and serum ANA titers (B), glomerular size (C), and glomerular cell count (D) were measured. *, p < 0.05; **, p < 0.01.

FIGURE 3

Rosiglitazone has functional effects in MRL-lpr and MRL-lpr adiponectin-deficient mice. MRL-lpr and MRL-lpr adiponectin-deficient (MRL-lpr. apn^−/−) female mice were maintained on normal diet or rosiglitazone-supplemented normal diet for 12 wk, starting at 6 wk of age and then disease parameters were measured. A, Body weights in MRL-lpr mice on normal diet (n = 10), MRL-lpr mice on rosiglitazone diet (n = 10), MRL-lpr.apn^−/− mice on normal diet (n = 6), and MRL-lpr.apn^−/− mice on rosiglitazone diet (n = 9). B, Serum adiponectin levels in MRL-lpr mice were measured by ELISA. C, Representative CD69 expression on splenic CD4⁺ T cells, CD8⁺ T cells, and B cells from MRL-lpr.apn^−/− mice treated with normal diet (red) or with rosiglitazone (blue) measured by flow cytometry. D, CD69 mean fluorescence intensity (MFI) on splenic CD4⁺ T, CD8⁺ T, and B cells from MRL-lpr.apn^−/− mice treated with normal diet (n = 5) or with rosiglitazone (n = 7) measured by flow cytometry. *, p < 0.05; ***, p < 0.001.

FIGURE 4

Rosiglitazone ameliorates disease in MRL-lpr mice but not in MRL-lpr mice lacking adiponectin. Female MRL-lpr and MRL-lpr adiponectin-deficient (MRL-lpr.apn^−/−) mice were maintained on normal diet or rosiglitazone-supplemented normal diet for 12 wk, starting at 6 wk of age and then disease parameters were measured. A, Rosiglitazone treatment decreases ANA titer in MRL-lpr mice, but not in MRL-lpr.apn^−/− mice. Rosiglitazone treatment decreases glomerular size (B) and glomerular cell number (C) in MRL-lpr mice, but not in MRL-lpr.apn^−/− mice. Adiponectin deficiency exacerbates renal disease in MRL-lpr mice as shown by D, an increase in glomerular crescents and E, an increase in fibrosis index. F, Representative photographs showing a decrease in glomerular size in rosiglitazone-treated MRL-lpr mice but not in rosiglitazone-treated MRL-lpr.apn^−/− mice, and an increase in glomerular size and cellularity in adiponectin-deficient mice compared with adiponectin-sufficient mice. Arrows indicate glomerular crescents. G, Representative photographs of kidney sections stained with Sirius red which stains areas of fibrosis red. Increased fibrosis is seen in adiponectin-deficient mice compared with adiponectin-sufficient mice. *, p < 0.05; **, p < 0.01; ***, p < 0.001.