Objective To explore the effect and mechanism of fenofibrate on renal tubular epithelial cell injury induced by high glucose (HG).
Methods Human renal tubular epithelial cells (HK2) were divided into control group (control), HG (HG treatment), HG+low fenofibrate (low fenofibrate, fenofibrate-L) (HG, 0.2 mmol/L fenofibrate treatment), HG+high fenofibrate(high fenofibrate, fenofibrate-H) (HG, 0.4 mmol/L fenofibrate treatment), HG+fenofibrate-H+small interfering RNA control (small interfering RNA control, si-NC) (siRNA control, HG, 0.4 mmol/L fenofibrate treatment), HG+fenofibrate-H+si-Nrf2 (nuclear factor E2-related factor 2-Small interfering RNA, si-Nrf2) (Nrf2 siRNA, HG, 0.4 mmol/L fenofibrate treatment), HG+Lv-NC (negative control lentivirus, Lv-NC) (negative control lentivirus, HG treatment) and HG+Lv-Nrf (Nrf over-expression lentivirus, Lv-Nrf) (Nrf over-expression lentivirus, HG treatment)group. Flow cytometry was utilized for detecting apoptosis and colorimetry for quantifying the content of superoxide dismutase (SOD), The level of malonaldehyde (MDA) was detected by visible spectrophotometry and the protein expressions of B cell lymphoma/leukemia-2 (Bcl-2), Bcl-2 associated X protein (Bax), Nrf2 and heme oxygenase-1 (HO-1) were detected by Western blot.
Results As compared with control group, the protein expressions of Nrf2 (0.26 ± 0.02) vs (0.49 ± 0.05), HO-1 (0.24 ± 0.02) vs (0.46 ± 0.04), SOD (16.25 ± 1.32) U/mLvs (33.25 ± 2.15) U/mL, MDA (9.58 ± 0.65) μmol/Lvs (3.05 ± 0.26) μmol/L and Bax (0.68 ± 0.08) vs (0.33 ± 0.03) dropped while cell apoptotic rate (23.25 ± 2.10)%, (16.02 ± 1.71)% vs (31.25 ± 2.15)% declined in HG group. The protein expression of Bcl-2 (0.23 ± 0.02) vs (0.54 ± 0.05) was down-regulated (P<0.05). As compared with HG group, the protein expressions of Nrf2 (0.36 ± 0.03), (0.44 ± 0.04)vs (0.26 ± 0.02), HO-1 (0.32 ± 0.03), (0.39 ± 0.02) vs (0.24 ± 0.02), SOD (22.23 ± 2.14) U/mL, (31.25 ± 2.01) U/mL vs (16.25 ± 1.32) U/mL, MDA (7.25 ± 0.61) μmol/L, (5.02 ± 0.51) μmol/L vs (9.58 ± 0.65) μmol/L and Bax (0.51 ± 0.05), (0.40 ± 0.04) vs (0.68 ± 0.08) dropped while cell apoptotic rate (23.25 ± 2.10)%, (16.02 ± 1.71)% vs (31.25 ± 2.15)% rose in HG+fenofibrate-L and HG+fenofibrate-H groups. The expression of Bcl-2 protein (0.39 ± 0.03), (0.47 ± 0.04) vs (0.23 ± 0.02) was up-regulated (P<0.05). As compared with HG+fenofibrate-H+si-NC group, the protein expressions of Nrf2 (0.30 ± 0.03)vs (0.44 ± 0.05), HO-1 (0.29 ± 0.04) vs (0.40 ± 0.05) and SOD (23.02 ± 2.15) U/mLvs (30.89 ± 4.15) U/mL declined in HG+fenofibrate-H+si-Nrf2 group. The contents of MDA (7.56 ± 0.78) μmol/Lvs (4.96 ± 0.57) μmol/L and Bax (0.53 ± 0.03) vs (0.42 ± 0.05) spiked and apoptotic rate (26.35 ± 2.47)% vs (16.58 ± 1.68)% rose. The protein expression of Bcl-2 was down-regulated (0.35 ± 0.03) vs (0.44 ± 0.05) (P<0.05). As compared with HG+Lv-NC group, the protein expressions of Nrf2 (0.49 ± 0.06)vs (0.29 ± 0.03), HO-1 (0.44 ± 0.04) vs (0.24 ± 0.05) and SOD (28.56 ± 2.65) U/mLvs (16.84 ± 1.84) U/mL spiked while apoptotic rate (15.03 ± 1.65)% vs (29.65 ± 1.84)%, MDA (6.25 ± 0.52) μmol/Lvs (9.05 ± 0.54) μmol/L and Bax (0.46 ± 0.05) vs (0.63 ± 0.08) dropped in HG+Lv-Nrf group, The protein expression of Bcl-2 was up-regulated (0.48 ± 0.04) vs (0.33 ± 0.04) (P<0.05).
Conclusion Fenofibrate suppressed the apoptosis and oxidative injury of renal tubular epithelial cells induced by HG. And the mechanism of action is correlated with an activation of Nrf2/HO-1 signal.