Effects of B cells activating factor on growth characteristics of mouse renal tubular epithelial cells

Abstract

Objective To investigate the expression of B cell activating factor (BAFF) and BAFF receptor (BAFF-R) on primary mouse renal tubular epithelial cells (RTECs), and the effect on growth characteristics of RTECs. Methods Primary mouse RTECs were isolated by enzyme digestion method, and cultured in the conditioned medium. After stimulated by 500 U/ml Interferon-γ (IFN-γ) for 48 h, the expression of BAFF and BAFF-R on RTECs were detected by Flow Cytometry (FCM). After treated with recombinant mouse BAFF and/or blockade B cell activating factor receptor-Fc fusion protein (BAFF-R-Fc) for 48 h, the transport ability of fluorescein sodium and cytokeratin-18 (CK-18) expression of RTECs were detected, respectively; The proliferation ability and the apoptosis rates of RTECs were tested by 3- (4, 5-dimenthylthiazol-2-yl)-5- (3-carboxymethoxyphenyl)-2- (4-sulfophenyl)-2H-tetrazolium (MTS) and FCM method, respectively; Data were analyzed by SPSS 17.0, and P<0.05 was considered to be statistically significant. Results BAFF-R expression on RTECs in the IFN-γ treated group significantly up-regulated, compared with control group (4 166.250±913.914 vs. 3 602.750±875.584, t=4.124, P=0.026). Fluorescein sodium transport experiment showed the average absorbance of BAFF stimulation group was significantly lower than BAFF-R-Fc+ BAFF group (0.011±0.003 vs. 0.020±0.007, t=-3.437, P=0.041), and control group (0.011±0.003 vs. 0.016±0.006, t=-3.572, P=0.038); Immunofluorescence results showed the average absorbance of BAFF stimulation group was significantly lower than that of BAFF-R-Fc+ BAFF group (0.032±0.005 vs. 0.043±0.007, t=-8.006, P=0.015), and control group (0.032±0.005 vs. 0.041±0.008, t=-4.603, P=0.044); Cell proliferation assay results showed that, A value of 5 ng/ml and 20 ng/ml BAFF group were significantly higher than that of control group (1.532±0.058 vs. 1.473±0.045; 1.509±0.056 vs. 1.473±0.045, t=5.636, P=0.030; t=5.765, P=0.029, respectively), and A value of 5 ng/ml BAFF group were significantly higher than that of BAFF-R-Fc+ BAFF group (1.532±0.058 vs. 1.477±0.050, t=5.085, P=0.037); Apoptosis test results indicated that the apoptosis rate of BAFF-treated group was significantly lower than that of BAFF-R-Fc+ BAFF group [(39.850±8.544)% vs. (42.950±8.330)%, t=-3.399, P=0.019], and control group [(39.850±8.544)% vs. (44.467±7.642)%, t=-3.020, P=0.029]. Conclusion BAFF signaling could promote the proliferation ability of RTECs, but down-regulate the epithelial cell characteristics and Ion transport ability of RTECs. Key words: Renal tubular epithelial cell; B cell activating factor; Cytokeratin-18; Ion transport; Proliferation