ABSTRACT
OBJECTIVE: Cyclosporine(CsA) and tacrolimus, albeit different in structure, exert immunosuppressive effect by similar mechanism. Although most of clinical manifestations, including nephrotoxicity, are similar in the patients using these drugs, there are some differences including gum hyperplasia, neurotoxicity, and hepatic fibrosis between two drugs. There are several reports about association between reactive oxygen species(ROS) and CsA. In contrast, tacrolimus is known to decrease ROS in central nervous system. Thus, we investigated the possibility of different effects of tacrolimus and CsA on the generation of ROS, on the synthesis and degradation of collagen. METHODS: Experiments were done in primary cultured mesangial cells between 4th and 8th passages. CsA was added to the culture dishes in different concentration(making final CsA concentration of 0, 2, 4, 8 microgram/milliliter) and N-acetylcysteine(NAC) was also added in another mesangial cell culture at 4 microgram/milliliter of CsA concentration; tacrolimus was added in similar pattern(making final tacrolimus concentration of 0, 0.1, 0.2, 0.4 microgram/milliliter, NAC in 0.2 microgram/milliliter of tacrolimus concentration). RESULTS: No significant decrease in viability was noted in both cell groups, but growth retardation was weak in tacrolimus treated cells comparing with CsA treated cells. By flow cytometry, we could find the generation of ROS in CsA treated cells, but not in tacrolimus treated cells. In RT-PCR, there is no significant difference in m-RNA expression for a number of molecules including collagen III, MMP-2, TIMP-2, MT1-MMP in either CsA treated cells or tacrolimus cells. But in zymogram, MMP-2 activities were decreased at higher CsA concentration, then increased with addition of NAC. In tacrolimus cells, MMP2 activity was not changed at 0.1 and 0.2 microgram/milliliter; but, at the concentration of 0.4 microgram/milliliter, changed and not reversed by NAC. MMP-9 activity was similar in both cells. CONCLUSION: We could find ROS generation in CsA treated human mesangial cells, but not in tacrolimus treated cells. We think this difference resulted in the decrease of post-transcriptional MMP-2 activity in CsA treated cells and we also think tacrolimus cells in our experiments were not influenced by ROS. From these results, tacrolimus and CsA are different in the generation of ROS that have some effects in the matrix accumulation in mesangial cells. These result does not mean that tacrolimus is superior to CsA in nephrotoxicity, because nephrotoxicity is similar between two drugs. In conclusion, the mechanisms of nephrotoxicity are different between CsA and tacrolimus.