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Triptriolide (T11) is a natural diterpene diepoxide that derived from Chinese traditional herb medicine (TCHM) Tripterygium wilfordii Hook.F (TWHF). From a structural point of view, T11 is very similar to triptolide (T9), one of the most effectively compounds in TWHF that have already been systematically investigated in the past decades. However, the basic functions and medicinal properties of T11 have not yet been well investigated mainly due to its low abundance in its plant organ. The present study aimed to investigate the protective effects of T11 on puromycin aminonucleoside (PAN) induced apoptotic mouse podocytes and the underlying mechanism. The results showed that T11 had no significant toxicity in podocytes in high dosage, and showed prominent protective effects on PAN induced podocytes injury. Further studies indicated that T11 might exert its protective effects by inhibiting of apoptosis and restoring of survival in PAN induced podocytes.

Triptolide(T9) is a predominant bioactive component extracted from Chinese herb Tripterygium wilfordii Hook F. (TwHF), and has multiple pharmacological activities, such as immunosuppressive and anti-inflammatory activities, et al. However, severe adverse effects and toxicity, particularly nephrotoxicity, limit its clinical application. It has been demonstrated that the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway could alleviate T9-induced nephrocyte damage. The aim of this study was to investigate the potential protective role of triptriolide (T11) against T9-induced nephrocyte apoptosis in vitro and in vivo. Renal injury models were established in human kidney 2 (HK2) cells and BALB/c mice using T9, and the protective effects of T11 were probed in vitro and in vivo, respectively. T9 induced nephrocyte damage in HK2 cells and BALB/c mice by induction of reactive oxygen species (ROS), lactate dehydrogenase (LDH), malondialdehyde (MDA) and glutathione (GSH) and reduction of superoxide dismutase (SOD), which resulted in the apoptosis of nephrocyte and injury of renal function. While, pretreatment of T11 effectively reversed these changes, resulting in the obvious decrease of oxidative stress and renal function parameters, ameliorated nephrocyte apoptosis, improved cell morphology, and higher increase of Nrf2, NAD(P)H: quinine oxidoreductase 1 (NQO1) and heme oxygenase 1 (HO-1) protein levels in vitro and in vivo. Altogether, T11 protected against T9-induced nephrocyte apoptosis possibly via suppressing oxidative stress.

Nrf2 (Nuclear Factor Erythroid 2 Related Factor 2) transcription factor not only regulates oxidative stress response, but also represses inflammation by regulating cytokines production and cross-talking with NF-κB signaling pathways. Nrf2 plays an essential role in liver injury induced by oxidative stress and inflammation. Triptriolide (T11) is a minor component of Tripterygium wilfordii Hook F. (TwHF), which can be obtained by hydrolysis reaction of triptolide (T9). The major purpose of this study is to clarify the regulating effects of T11 on oxidative stress and inflammation in vivo and in vitro. LPS-stimulated RAW 264.7 cells were used to verify the regulating effects of T11 on oxidative stress (ROS and Nrf2 signaling pathway) and inflammatory cytokines production (TNF-α, IL-6 and IL-1β). The antioxidant responsive element (ARE) luciferase assay was employed to evaluate Nrf2 activation effect of T11 in HEK-293T cells. Lipopolysaccharides (LPS) induced acute liver injury (ALI) in BALB/c mice were used to study the protective effects (ALT, AST, MDA, SOD, histopathology and neutrophils/macrophages filtration) and the underlying protection mechanisms of ALI amelioration (Nrf2 and NF-κB signaling pathway) of T11. Firstly, the results showed that T11 can not only effectively decrease the productions of inflammatory cytokines (TNF-α, IL-6 and IL-1β), ROS and NO in LPS-stimulated RAW 264.7 cells, but also further significantly increase the activity of Nrf2 in HEK-293T cells. Secondly, the results suggested that T11 could dramatically decrease the oxidative stress responses (SOD and MDA) and inflammation (histopathology, neutrophils/macrophages filtration, TNF-α, IL-6 and IL-1β production) in LPS-induced ALI in BALB/c mice. Finally, the results implied that T11 could dramatically increase Nrf2 protein expression and decrease p-TAK1, p-IκBα and NF-κB protein expression both in vivo and in vitro. In conclusion, our findings indicated that T11 could alleviate LPS induced oxidative stress and inflammation by regulating Nrf2 and NF-κB signaling pathways in vitro and in vivo, which offers a novel insights for the application of TwHF in clinical.