Mycophenolic acid inhibits the phosphorylation of NF-κB and JNKs and causes a decrease in IL-8 release in H2O2-treated human renal proximal tubular cells

Ischaemia-reperfusion injury is a common occurrence in renal transplantation and may affect the long-term survival of the allograft. Oxidative stress may play a crucial role in this, with reactive oxygen species formed during reperfusion causing direct cellular damage as well as activating pro-inflammatory pathways. A human proximal tubule cell line (HK-2) was subjected to hydrogen peroxide (H2O2) stress that resulted in phosphorylation of c-jun N-terminal kinases (JNKs) and the transcription factor NF-κB at Ser276, both of which have been associated with inflammation. Interleukin (IL)-8 production also increased upon H2O2 stimulation. Pre-incubation of the cells with mycophenolic acid (MPA) resulted in reduced phosphorylation of both JNKs and NF-κB, and reduced IL-8 release in H2O2-stimulated HK-2 cells. MPA also reduced the H2O2-induced phosphorylation of p38 MAP (mitogen-activated protein) kinase, the extracellular-signal regulated kinase 1/2 (ERK1/2), Akt kinase and the transcription factor CREB (cyclic AMP response element binding protein). In rat kidneys subjected to ischaemia-reperfusion, an increase in both pJNK1/2 and pNF-κB was observed, which was reduced in kidneys obtained from mycophenolate mofetil (MMF)-treated rats. These results suggest that MPA may inhibit pro-inflammatory responses in the kidney by inhibiting activation of pro-inflammatory molecules in both the kidney and human renal proximal tubular cells subjected to oxidative stress.