Cyclophosphamide treatment for hypertension and renal injury in an experimental model of systemic lupus erythematosus

Cardiovascular disease is the major cause of mortality among patients with the autoimmune disorder systemic lupus erythematosus (SLE). Our laboratory previously reported that immunosuppression with mycophenolate mofetil, a common therapy in patients with SLE, attenuates the development of hypertension in an experimental model of SLE. Cyclophosphamide (CYC) is another common therapy for patients with SLE that has contributed to improved disease management; however, its impact on the development of hypertension associated with SLE is not clear. We tested whether treatment with CYC (25 mg/kg, once/week, IP injection) for 4 weeks would attenuate hypertension in an established female mouse model of SLE with hypertension (30‐week‐old NZBWF1 females). Plasma anti‐dsDNA IgG levels, pathogenic for the disease, were lower in CYC‐treated SLE mice compared to vehicle‐treated SLE mice, suggesting efficacy of the therapy to suppress aberrant immune system function. Mean arterial pressure (MAP) was assessed by carotid artery catheters in conscious mice. Treatment did not attenuate the development of hypertension when compared to vehicle‐treated SLE mice; however, urinary albumin excretion was lower in CYC‐treated animals. Corresponding with the reduction in autoantibodies, data suggest that CYC treatment lowered circulating CD45R+ B cells. Paradoxically, circulating CD11b+Ly6G+ neutrophils were increased in CYC‐treated SLE mice compared to vehicle treated. Estrus cycling data also suggest that CYC treatment had an impact on ovarian function that may be consistent with reduced circulating estrogen levels. Taken together, these data suggest that CYC treatment attenuates autoantibody production and renal disease during SLE, but that the potential to affect MAP may be blunted by the increase in circulating neutrophils and CYC's impact on ovarian function. The impact of immunosuppression with cyclophosphamide (CYC) on blood pressure during autoimmune disease was examined. Although CYC protected the kidneys and reduced the markers of immune system activation, treatment did not affect blood pressure. The treatment altered ovarian function suggesting the possibility that ovarian toxicity may have prevented potential antihypertensive actions of CYC.