Effects of Mycophenolic Acid and Rapamycin on Toll-like Receptor Expression in Hypoxic Human Proximal Tubular Epithelial Cells / 대한이식학회지

ABSTRACT

BACKGROUND: Toll like receptor (TLR), an element of innate immunity, is upregulated by Ischemia/reperfusion (IR) injury and may be involved in adaptive immune response. Immunosuppressive agents may increase or attenuate IR injury and TLR expression. To explore the involvement of TLRs in hypoxic tubular injury and modification by mycophenolic acid (MPA) rapamycin (RAP), this study examined TLR expression in hypoxia-induced human renal proximal tubular epithelial cells (HK-2). METHODS: HK-2 cells were cultured in keratinocyte-SFM media supplemented with epidermal growth factor and bovine pituitary extract. The Induction of hypoxia was achieved using GasPak pouch system. TLR 2, 3, and 4 mRNA expression was analyzed by real time RT-PCR using SYBR green and TLR 4 protein expression was evaluated by Western blot analysis. MPA at concentration of 100 nM and 1uM and RAP at concentration of 20, 50, and 100 nM were added to culture medium. RESULTS: TLR4 but noTLR2 or TLR3 mRNA expressions increased in hypoxic HK-2 cells at 24 and 48 hrs. TLR4 protein expression also increased in hypoxic HK-2 cells at 24 and 48 hrs. MPA (100 nM and 1uM) and RAP (20, 50, and 100 nM) decreased hypoxia-induced TLR4 mRNA expression in HK-2 cells compared to normoxia at 24 hrs. However, TLR4 protein expression was decreased only by RAP at 20 and 50 nM. CONCLUSIONS: The results suggest that RAP may modify hypoxic renal tubular damage by decreasing TLR4-mediated inflammatory and immune reactions.