Mycophenolate mofetil significantly reduces leukocyte graft infiltration after heterotopic cardiac transplantation in a rat model: comparative study with cyclosporine and FK 506.

BACKGROUND: The purpose of the study was to evaluate the effects of cyclosporine (CsA), FK 506 and mycophenolate mofetil (MMF) on graft-infiltrating leukocytes (CD4, CD8, CD11a, CD18) after cardiac transplantation in rats. METHODS: Three hundred forty animals were transplanted and randomly divided into 4 groups: CsA, 3 mg/kg/d (n = 74); MMF, 40 mg/kg/d (n = 96); FK 506, 0.3 mg/kg/d (n = 96); and a control group receiving no immunosuppressive therapy (n = 74). Three or 4 animals from each group were killed at intervals of 1 to 4 days up to Day 60. Immunohistochemistry was performed using monoclonal antibodies (MAb) against CD4, CD8, CD11a and CD18. Positively stained cells were analyzed in the perivascular space (PVS) of intra- and epicardial arteries. Statistical analysis was performed using area-under-the-curve assessment with an extended t-test. RESULTS: CsA and FK 506 reduced the presence graft-infiltrating leukocytes (CD4, CD8, CD11a, CD18) in the PVS of intra- and epicardial arteries when compared with control animals. MMF therapy resulted in a further significant reduction in infiltrating leukocytes when compared with the 2 calcineurin inhibitors. MMF had a faster onset of action than the calcineurin inhibitors. CsA and FK 506 required 12 to 20 additional days to achieve the reducing effect of graft infiltration seen in MMF-treated animals. CONCLUSION: MMF possesses potent infiltration-blocking properties and its application leads to a greater reduction of cellular infiltration in the course of transplant rejection when compared with calcineurin inhibitors.

Two good reasons for an angiotensin-II type 1 receptor blockade with losartan after cardiac transplantation: reduction of incidence and severity of transplant vasculopathy.

Despite considerable progress in immunosuppressive therapy, the incidence and severity of transplant vasculopathy (TVP) after cardiac transplantation have not declined. The renin-angiotensin system (RAS) plays a pivotal role in the proliferation of vascular smooth muscle cells (VSMCs) contributing to TVP. We compared the effects of an angiotensin-II blocker, losartan (AT(1) blocker), and an angiotensin-converting enzyme (ACE) inhibitor, enalapril, on the incidence of diseased vessels and the severity of experimental TVP in the Lewis-to-Fischer rat heterotopic heart transplantation model. Recipients were randomly divided into six groups, group 1: no therapy, group 2: 3 mg/kg per day cyclosporine (CyA) s.c., group 3: CyA and 10 mg/kg per day losartan p.o., group 4: CyA and 40 mg/kg per day enalapril p.o., and groups 5 and 6: as groups 3 and 4, but additionally pre-treated with losartan or enalapril 7 days prior to transplantation. Eighty days after grafting, we assessed the incidence and severity of TVP, expressed as percentage of diseased vessels and mean vessel occlusion (MVO), by digitizing morphometry. CyA and CyA/enalapril post-treatment significantly reduced MVO, compared with controls, but not the incidence. Additional reduction of MVO was achieved in CyA/enalapril pre-treatment and both CyA/losartan pre- and post-treatment groups when compared with CyA and untreated controls. However, only losartan post-treatment in combination with CyA reduced both incidence and MVO. Our results validate the important role of the RAS in neointimal proliferation after cardiac transplantation. Losartan appears to be superior to enalapril in preventing TVP after experimental cardiac transplantation. Therefore, AT(1) blockade with losartan might be a therapeutic option for the prevention of TVP in human heart recipients.