RESUMO
OBJECTIVE: To study the inhibitory effect of paeoniflorin (PAE) on TNF-α-induced TNF receptor type I (TNFR1)-mediated signaling pathway in mouse renal arterial endothelial cells (AECs) and to explore its underlying molecular mechanisms. METHODS: Mouse AECs were cultured in vitro and then they were treated by different concentrations PAE or TNF-α for various time periods. Expression levels of intercellular cell adhesion molecule-1 (ICAM-1) were detected in the normal group (cultured by serum-free culture media), the TNF-α group (cultured by 2-h serum-free culture media plus 6-h TNF-α 30 ng/mL), the low dose PAE group (cultured by 2-h PAE 0.8 µmo/L plus 6-h TNF-α 30 ng/mL), the middle dose PAE group (cultured by 2-h PAE 8 µmol/L plus 6-h TNF-α 30 ng/mL), the high dose PAE group (cultured by 2-h PAE 80 µmol/L plus 6-h TNF-α 30 ng/mL) with Western blot analysis. Nuclear translocation of transcription factor NF-κB (NE-κB) was detected in the normal group (cultured by serum-free culture media), the TNF-α group (cultured by 2-h serum-free culture media plus 45-mm TNF-α 30 ng/mL), and the high dose PAE group (cultured by 2-h PAE 80 µmol/L plus 45-min TNF-α 30 ng/mL) by immunofluorescent staining. Expression levels of the phosphorylation of extracellular signal-regulated (protein) kinase (ph-ERK) and p38 (ph- p38) were detected in the normal group (cultured by serum-free culture media) and the high dose PAE group (2-h PAE 80 µmol/L culture) by Western blot. NF-κB inhibitor-α (IκBα) protein expressions were detected in the normal group (cultured by serum-free culture media), the TNF-α group (cultured by 2-h serum-free culture media plus 30-min TNF-α 30 ng/mL), the high dose PAE group (cultured by 2-h PAE 80 µmol/L plus 30-min TNF-α 30 ng/mL), the p38 inhibitor group (SB group, pretreatment with SB238025 25 µmol/L for 30 min, then treated by PAE 80 µmol/L for 2 h, and finally treated by TNF-α 30 ng/mL for 30 min), the ERK inhibitor group (PD group, treated by PD98059 50 µmol/L for 30 min, then treated by PAE 80 µmol/L for 2 h, and finally treated by TNF-α 30 ng/mL for 30 min) by Western blot. RESULTS: Compared with the normal group, ICAM-1 protein expression levels obviously increased (P < 0.01). Compared with the TNFα group, ICAM-1 protein expression levels were obviously inhibited in the high dose PAE group (P < 0.05). Protein expression levels of ph-p38 and ph-ERK were obviously higher in the hIgh dose PAE group (P < 0.05). Compared with the normal group, IκBα protein expression levels obviously decreased in the TNF-α group (P < 0.01). Compared with the TNFα group, TNF-α-induced IκBα degradation could be significantly inhibited in the high dose PAE group (P < 0.01); the inhibition of PAE on IκBα degradation could be significantly inhibited in the SB group (P < 0.05). NF-κB/p65 signal was mainly located in cytoplasm in the normal group. NF-κB/p65 was translocated from cytoplasm to nucleus after stimulated by 45 min TNF-α in the TNF-α group, while it could be significantly inhibited in the high dose PAE group. CONCLUSIONS: PAE inhibited TNF-α-induced expression of lCAM-1. Its action might be associated with inhibiting TNFR1/NF-κB signaling pathway. p38 participated and mediated these actions.
