Icariside Ⅱ Contributes to Epimedii folium-Induced Hepatotoxicity Through Enhancing NLRP3 Inflammasome Activation

Abstract

Idiosyncratic drug-induced liver injury (IDILI) continues to be a leading cause of failures in drug development and the main reason for post-marketing safety warnings and withdrawals of drugs. Epimedii folium (EF), an herbal medicine widely used in China, Japan, and Korea, has been shown to cause idiosyncratic liver injury, but the underlying mechanisms are poorly understood. Increasing evidences have indicated that most cases of IDILI are immune mediated. Here, we report that icariside Ⅱ (ICS Ⅱ), the major active and metabolic constituent of EF, causes idiosyncratic liver injury by promoting NLRP3 inflammasome activation. ICS Ⅱ enhances NLRP3 inflammasome activation triggered by adenosine triphosphate (ATP) and nigericin, but not silicon dioxide (SiO2), monosodium urate crystal (MSU) or cytosolic lipopolysaccharide (LPS). Moreover, the activation of NLRC4 and AIM2 inflammasomes is not affected by ICS Ⅱ. Mechanistically, synergistic induction of mitochondrial reactive oxygen species (mtROS) is a crucial contributor to the enhancing effect of ICS Ⅱ on ATP- or nigericin-induced NLRP3 inflammasome activation. Importantly, in vivo data show that a combination of nonhepatotoxic doses of LPS and ICS Ⅱ causes liver injury in wild-type mice but not NLRP3-knockout mice. In conclusion, ICS Ⅱ acts as a specific promoter to increase ATP- and nigericin-induced NLRP3 inflammasome activation, which is responsible for EF-induced liver injury. Our findings also suggest that ICS Ⅱ or EF should be avoided in cases of diseases that are associated with ATP/nigericin-induced NLRP3 inflammasome activation, which may be risk factors for EF-induced liver injury. Funding Statement: This work has been supported by National Natural Science Foundation of China (81874368, 81630100), Beijing Nova Program (Z181100006218001), National Science & Technology Major Project “Key New Drug Creation and Manufacturing Program” (2017ZX09301022, 2018ZX09101002). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: All experimental procedures in this study were performed according to the guidelines of laboratory animals care and use and approved by the animal ethics committee of the Fifth Medical Centre, Chinese PLA (People’s Liberation Army) General Hospital.