Extrahepatic cytochrome P450s play an insignificant role in triptolide-induced toxicity

Abstract

Background: Triptolide, an active ingredient of Chinese medicine plant Tripterygium wilfordii Hook.f., has been shown to exert anti-tumor, immunosuppressive, anti-inflammatory, and anti-fertility pharmacological effects. However, triptolide also causes severe side effects, which are manifested as toxicities in multiple organs. The aim of this study was to analyze the role of extrahepatic cytochrome P450 enzymes in triptolide-induced toxicity.

Methods: Xh-CL mouse model with normal liver, but low extrahepatic P450 expression levels was used in this study. Xh-CL mice and C57BL/6 (wildtype, WT) mice were treated with 200 μg/kg triptolide intraperitoneally every other day for 30 days. The serum levels of alanine aminotransferase (ALT), aspartate transaminase (AST), creatine (Cre), and blood urea nitrogen (BUN) were detected by kits. The changes of tissue were observed with H&E staining. Two groups of mice (Xh-CL and WT animals), were received a single dose of 1 mg/kg TP by oral gavage for pharmacokinetic analysis.

Results: Xh-CL mice displayed higher serum levels of ALT, AST, Cre, and BUN compared to untreated Xh-CL mice. The organ-to-body weight ratio for spleen was high, while that for testes was low. Histopathological changes were observed in multiple organs. However, compared with triptolide-treated WT mice, no significant differences in either blood chemistry or histopathology were recorded. Furthermore, pharmacokinetic studies showed no significant differences between triptolide-treated Xh-CL and WT mice.

Conclusions: Our findings suggest that sub-chronic triptolide treatment can induce toxicities in mouse kidney, spleen, and testis with or without normal local P450 functions. Therefore, extrahepatic P450s play an insignificant role in triptolide-induced toxicity.

Keywords: Cytochrome P450; Extrahepatic toxicity; Pharmacokinetic; Triptolide; Xh-CL mouse model.

Fig. 1

Effects of triptolide (TP) intraperitoneal (i.p.) injection on serum biochemical parameters in Xh-CL mice and WT mice. TP was administered at doses of 0.1 and 0.2 mg/kg; the control mice were administered with a vehicle, mice were dosed every other day for 30 days. a Alanine aminotransferase (ALT); b aspartate transaminase (AST); c creatinine; d blood urea nitrogen (BUN). ^#p < 0.05, ^##p < 0.01 vs. control

Fig. 2

Comparison of liver lesions in Xh-CL and WT mice following triptolide oral treatment (H&E staining, ×200). The mice were administered with 0.1 mg/kg (b, e) or 0.2 mg/kg (c, f) triptolide. The control mice received a vehicle (a, d). Mice were dosed every other day for 30 days. Arrows indicate necrotic and swollen hepatocytes

Fig. 3

Comparison of kidney lesions in Xh-CL and WT mice following triptolide oral treatment (H&E staining, ×200). The mice were administered with 0.1 mg/kg (b, e) or 0.2 mg/kg (c, f) triptolide. The control mice received a vehicle (a, d). Mice were dosed every other day for 30 days. Arrows indicate renal proximal tubular dilation; some protein casts are visible

Fig. 4

Comparison of testicular lesions in Xh-CL and WT mice following triptolide oral treatment (H&E staining, ×200). The mice were administered with 0.1 mg/kg (b, e) or 0.2 mg/kg (c, f) triptolide. The control mice received a vehicle (a, d). Mice were dosed every other day for 30 days. Squares indicate reduced primary and secondary spermatocytes in the seminiferous tubules

Fig. 5

Comparison of splenic lesions in Xh-CL and WT mice following triptolide oral treatment (H&E, ×200). The mice were administered with 0.1 mg/kg (b, e) or 0.2 mg/kg (c, f) triptolide. The control mice received a vehicle (a, d). Mice were dosed every other day for 30 days. Squares indicate bleeding of dilated splenic sinus. Arrows indicate splenic atrophy

Fig. 6

Levels of triptolide in the liver (a), kidney (b), testis (c) and spleen (d) of Xh-CL and WT mice 24 h after oral treatment. The mice were administered with 0.1 or 0.2 mg/kg triptolide. The control mice received a vehicle. Mice were dosed every other day for 30 days. Mean ± standard deviation (indicated by error bars) are shown. No significant difference was observed between the groups at each dosage

Fig. 7

Triptolide (1.0 mg/kg) clearance in Xh-CL and WT mice. Mean ± standard deviation (indicated by error bars) are shown. No significant difference was observed between the groups at any time point