Attenuation of murine lupus nephritis by mycophenolate mofetil.

Mycophenolate mofetil (MMF) is the morpholin- oethyb ester of mycophenolic acid, which is its active metab- olite. MMF is effective in prolonging survival of albografts and xenografts. However, little is known about the effects and the main mechanism of action of MMF in autoimmune diseases. In this study, the effect of MMF on the spontaneous disease progression in the MRL/Ipr mouse model of lupus was exam- med. Eight-week-old MRL/lpr mice (n = 18) were orally treated with MMF dissolved in a vehicle (90 mg/kg) once a day. Control animals received vehicle alone (n = 17). The incidence of albuminuria (>300 pg/l8 h) was significantly reduced by MMF treatment compared with vehicle-treated controls (cumulative incidence of albuminuria at 23 wk in MMF-treated mice; 22% versus 88% in controls; P = 0.0001). The glomerulonephritis was histologically less severe in MMF- treated mice than in control mice (P = 0.005). Furthermore, in immunofluorescence studies the amount of immunoglobulin and C3 deposits in the glomerular capillary wall was signifi- cantly less in MMF-treated mice (P � 0.002). Surprisingly, in vivo no clear-cut immune-modulating effects were observed because there were no differences between MMF-treated and control animals with regard to autoantibody formation. Also, spleen enlargement and numbers of CD3�, CD4�, and CD8� T cells in spleen, lymph nodes, and peripheral blood were not different between both groups. Furthermore, no immunosup- pressive properties of 90 mg/kg MMF were found in BALB/c mice on delayed-type hypersensitivity and primary antibody response to methylated bovine serum albumin. Interestingly, renal perfusion experiments revealed that binding of nucleo- some/antinucleosome complexes to the glomerubar basement membrane is decreased in MMF-treated mice compared with control mice. It is concluded that MMF suppresses the devel- opment of bupus glomerulonephritis and albuminuria in MRL/ lpr mice. The observed reduction of glomerubar immunoglob- ulin deposits in MMF-treated mice and the renal perfusion studies indicate that MMF treatment beads to a decreased binding of immune complexes in the gbomerular capillary wall in lupus nephritis.