Supplementary Material for: Inflammation is more sensitive than cell proliferation in response to rapamycin treatment in polycystic kidney disease

Introduction: It has been reported that rapamycin inhibited inflammation in renal interstitial diseases. We therefore hypothesized that rapamycin could attenuate inflammation in polycystic kidney disease (PKD).
Methods: Han:SPRD rats were treated with rapamycin by daily gavage from 4 weeks to 12 weeks of age at the dosage of 0.5mg/kg/day (low dose) or 1mg/kg/day (high dose). WT9-12 human PKD cells were treated with various concentrations of rapamycin.
Results: Two-kidney/total body weight ratio and cystic index in Cy/+ kidneys were significantly reduced with the treatment of low-dose rapamycin, and further reduced by the treatment with high-dose rapamycin. However, the renal function of Cy/+ rats was equally improved by the treatment with either low or high-dose rapamycin. The renal cell proliferation was significantly decreased in Cy/+ kidneys with the treatment of low-dose rapamycin and was further decreased with the treatment of high-dose rapamycin as examined by Ki-67 staining. The phosphorylation of S6K in cystic kidneys was decreased by low-dose rapamycin and further decreased by high-dose rapamycin. Both low and high-dose rapamycin treatment decreased macrophage infiltration and the expression of CFB, MCP-1, and TNF-α to a similar level. The expression of CFB, MCP-1, and TNF-α and phosphorylation of S6K were inhibited in WT9-12 cells treated with 10 nM rapamycin at 24H and 48H, respectively. Moreover, the phosphorylation of Akt was not increased by the 1 nM and 10 nM of rapamycin and enhanced by 1 μM rapamycin treatment. Interestingly, WT9-12 cell proliferation could be inhibited by 1 μM rapamycin.
Conclusions: Low dose of rapamycin could inhibit inflammation and protect renal function in PKD. Inflammation is more sensitive than cell proliferation in response to rapamycin treatment in PKD.