Molecular Mechanisms of Cyclosporin A Inhibition of the Cytokine-induced Matrix Metalloproteinase-9 in Glomerular Mesangial Cells

The effects of the immunosuppressants cyclosporin A (CsA) and tacrolimus (FK506) on the IL-1beta-induced matrix metalloproteinase-9 (MMP-9) were investigated. Impairment of the protease-antiprotease balance contributes to renal fibrosis, which is observed collectively under long-term treatment with either immunosuppressant. It is demonstrated that CsA, in contrast to FK506, reduced the IL-1beta-induced MMP-9 content in conditioned media of mesangial cells, which coincides with a reduction in the cytokine-induced MMP-9 mRNA level. Similar to FK506, the VIVIT peptide, a specific inhibitor of the nuclear factor of activated T cells, did not affect the cytokine-induced MMP-9 level. Moreover, CsA caused a dose-dependent inhibition on the IL-1beta-induced luciferase activity of a 1.3-kb MMP-9 promoter fragment. Concomitant, electrophoretic mobility shift assay revealed that CsA selectively inhibits the cytokine-induced DNA binding of activator protein-1 and NF-kappaB. The effects on NF-kappaB binding were accompanied by a marked reduction in the nuclear content of the p65 subunit of NF-kappaB. Accordingly, CsA specifically impaired the IL-1beta-triggered degradation of inhibitory NF-kappaB. The suppressive effects by CsA on MMP-9 expression were accompanied by a reduction in the cytokine-induced phosphorylation of p42/p44 and c-Jun N-terminal Kinase (JNK). It is interesting that only the JNK inhibitor SP600125 impaired the cytokine-triggered MMP-9 level, suggesting that CsA, via inhibition of the JNK pathway, negatively interferes with the NF-kappaB-dependent transcriptional control of MMP-9. Interference with MMP-9 transcription may account for the accumulation of extracellular matrix underlying the high fibrotic potential of CsA during anti-inflammatory therapies with calcineurin inhibitors.