Abstract: Objective To study the expression of high mobility group box-1 protein (HMGB1) and Toll-like receptor 4 (TLR4) in renal proximal epithelial cells following by anoxia/reoxygenation injury and their underlying roles in cell apoptosis. Methods Rat primary proximal tubule epithelial cells (PTECs) were cultured in six-well plates and randomly divided into Control, anoxia/reoxygenation group(A/R), HMGB1 antibody treatment group (A/R+HMGB1) and TLR4 antibody treatment group (A/R+TLR4). RT-PCR was used to detect the mRNA levels of HMGB1 and TLR4; Western blot was used to detect the protein expression of HMGB1, TLR4 and the apoptosis-related factors, such as Bcl-2, Bax，CHOP and caspase-8; Flow cytometry was used to detect apoptosis. Results The expression of mRNA and protein of TLR4 and HMGB1 increased significantly in A/R group compared with control (P<0.01). The apoptosis cells in A/R group increased significantly compared with control (P<0.01). The expression of Bax, CHOP and caspase-8 increased significantly compared with control (P<0.01). While the expression of Bcl-2 decreased compared with control (P<0.05). After HMGB1 and TLR4 antibodies treatment, the apoptosis cells in A/R+HMGB1 group and A/R+TLR4 group decreased significantly compared to A/R group (P<0.05). The expression of Bax, CHOP and caspase-8 also decreased significantly compared with A/R group (P<0.05). The change of Bcl-2 protein expression was not obviously. Conclusions HMGB1-TLR4 axis promote apoptosis of PTECs following A/R injury.

Key words: TLR4, HMGB1, Apoptosis