17β-estradiol protects against the progression of hypertension during adulthood in a mouse model of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disorder with a high prevalence of hypertension and cardiovascular disease. Because SLE predominantly affects women, estrogen is commonly implicated as a contributor to SLE disease progression. Using an established mouse model of SLE (female NZBWF1), we tested whether estrogen has a causal role in the development of hypertension in adulthood. Thirty-week-old SLE and control mice (NZW/LacJ) underwent either a sham or ovariectomy (OVX) procedure. 17β-Estradiol (E2; 5 μg/mouse, twice/week, subcutaneously) was administered to a subset of OVX mice. Mean arterial pressure (in mm Hg) was increased in SLE mice (134±4 versus 119±3 in controls). Contrary to our hypothesis, OVX exacerbated the hypertension in female SLE mice (153±3; P<0.05 versus SLE sham), and repletion of E2 prevented the OVX-induced increase in blood pressure (132±2). The prevalence of albuminuria was increased in SLE mice compared with controls (37% versus 0%). OVX increased the prevalence in SLE mice (70% versus 37% in SLE shams). Repletion of E2 completely prevented albuminuria in OVX SLE mice. Renal cortical tumor necrosis factor α was increased in SLE mice compared with controls and was further increased in OVX SLE. The OVX-induced increase in renal tumor necrosis factor α expression was prevented by repletion of E2. Treatment of OVX SLE mice with the tumor necrosis factor α inhibitor, etanercept, blunted the OVX-induced increase in blood pressure (140±2) and prevalence of albuminuria (22%). These data suggest that 17β-estradiol protects against the progression of hypertension during adulthood in SLE, in part, by reducing tumor necrosis factor α.