Insulin resistance and obesity in a mouse model of systemic lupus erythematosus

Accumulating data indicate that metabolic syndrome is an inflammatory condition. Systemic lupus erythematosus (SLE) is an autoimmune disorder associated with nephritis and cardiovascular disease. Evidence suggests that individuals with SLE are at risk for developing insulin resistance; however, this has not been directly examined. Using an established mouse strain with SLE (NZBWF1), we examined whether SLE is associated with increased body weight and fat deposition. Mean arterial pressure was significantly increased (140 +/- 4 versus 114 +/- 2 mm Hg; n >= 5) in SLE mice by 36 weeks of age compared with control mice (NZW/LacJ). Body weight in SLE mice was higher at each age compared with controls by 12%, 22%, and 34% (n > 30). Visceral adipose tissue weight was increased in SLE by 44%, 74%, and 117% at 8, 20, and 36 weeks, respectively (n >= 12). Plasma leptin was increased in SLE mice (8.6 +/- 1.0 versus 24.7 +/- 2.2 ng/mL; n = 5), and renal and adipose tissue exhibited macrophage infiltration. Fasted insulin was higher in SLE mice (0.6 +/- 0.1 versus 1.4 +/- 0.3 ng/mL; n >= 10), but fasted glucose was not different (94 +/- 5 versus 80 +/- 9; n >= 9). A glucose tolerance test caused a significantly greater and longer increase in blood glucose from mice with SLE compared with control mice. Food intake was not different between control and SLE mice. However, mice with SLE demonstrated lower levels of nighttime activity than controls. These data show that the NZBWF1 strain may be an important model to study the effects of obesity and insulin resistance on SLE- associated hypertension.