Lipopolysaccharide administration increases the susceptibility of mitochondrial permeability transition pore opening via altering adenine nucleotide translocase conformation in the mouse liver

Lipopolysaccharide (LPS), a component of the outer membrane of gram-negative bacteria, induces various biological reactions in vivo. Our previous study suggested that LPS administration disrupts respiratory chain complex activities, enhances reactive oxygen species production, especially in the liver mitochondria, and sensitizes mitochondrial permeability transition (MPT) pore opening in rats. However, it is unknown whether LPS-induced MPT pore opening in rats is similarly observed in mice and whether the mechanism is the same. LPS administration to mice increased not only cyclosporin A-sensitive swelling (MPT pore opening) susceptibility, but also induced cyclosporin A-insensitive basal swelling, unlike in rats. In addition, respiratory activity observed after adding ADP was significantly decreased. Based on these results, we further investigated the role of adenine nucleotide translocase (ANT). Carboxyatractyloside (CATR; an ANT inhibitor) treatment decreased respiratory activity after ADP was added in vehicle-treated mitochondria similarly to LPS administration. Additionally, CATR treatment increased MPT pore opening susceptibility in LPS-treated mitochondria compared to that of vehicle-treated mitochondria. Our study shows that ANT maintained a c-state conformation upon LPS administration, which increased MPT pore opening susceptibility in mice. These results suggest that LPS enhances MPT pore opening susceptibility across species, but the mechanism may differ between rat and mouse.

Signal Detection of Potential Hepatotoxic Drugs: Case-Control Study Using Both a Spontaneous Reporting System and Electronic Medical Records

Drug-induced liver injury (DILI) is a common adverse drug event. Spontaneous reporting systems such as the Japanese Adverse Event Report Database (JADER) have been used to evaluate the association between drugs and adverse drug events. However, the association of drugs with adverse drug events may be overestimated due to reporting biases. Therefore, it is important to objectively evaluate the association using liver function test values. The aim of the present study was to predict potential hepatotoxic drugs using real-world data including electronic medical records and the JADER database. A total of 70009 (2779 with DILI and 67230 without DILI) and 438515 (10235 with DILI and 428280 without DILI) Japanese adult patients were extracted from electronic medical records and the JADER database, respectively. Drugs with ≥100 DILI patients in both of the two databases were regarded as suspected drugs for DILI. We used multivariate logistic regression to evaluate the association between the suspected drugs and increased risk of DILI. Among the suspected drugs, broad-spectrum antibiotics such as meropenem, tazobactam/piperacillin and ceftriaxone were significantly associated with an increased risk of DILI, and meropenem had a greater risk of DILI in both of the two databases. Additionally, there were significant associations of mosapride and L-carbocisteine with increased risk of DILI. In addition to well-known associations between antibiotic drugs and DILI, mosapride and L-carbocisteine were found to be new potential signals of drugs causing hepatotoxicity. This study indicates potential hepatotoxic drugs that require further causality assessment.

Research advances in pathogenesis and diagnostic markers of drug-induced liver injury

The pathogenesis of drug-induced liver injury (DILI) is complex, involving a variety of factors; so far, it has not been very clear yet. In recent years, scholars have carried out many studies on the pathogenesis of DILI. The diversity of clinical manifestations and the lack of specific and unified diagnostic criteria for DILI increase the complexity of diagnosis and treatment of DILI. In order to strengthen the understanding of DILI, this paper summarizes the recent research progress on the pathogenesis and diagnostic markers of DILI.

[The trends in predicting drug-induced liver injury]

Drug-induced liver injury (DILI) is the major reason for the discontinuation of new drug development and the withdrawal of drugs from the market. Hence, the evaluation systems which predict the onset of DILI in the pre-clinical stage are needed. To date, many researchers have conducted the mechanism of DILI, but the DILI prediction is poor because of the complexity of DILI. In this regard, based on the information obtained from basic research and clinical case, several pharmaceutical companies have been developed DILI prediction methods with high sensitivity and specificity by combining multiple targets. Another reason for low predictability is derived from the conventional culture method which causes a rapid decrease in hepatocyte function. To overcome these problems, the construction of a high-level in vitro evaluation system has been developed and applied to DILI evaluation. On the other hand, these in vitro evaluation methods require a lot of labor and cost so, in silico prediction methods have also been constructed in recent years. Based on this point, this article reviews the trends in DILI prediction systems in the non-clinical stage.

Hypoxia/reoxygenation exacerbates drug-induced cytotoxicity by opening mitochondrial permeability transition pore: Possible application for toxicity screening

Recently, mitochondrial dysfunction is thought of as an important factor leading to a drug-induced liver injury. Our previous reports show that mitochondria-related toxicity, including respiratory chain inhibition (RCI) and reactive oxygen species (ROS) induction, can be detected by the modification of sugar resource substitution and high oxygen condition. However, this in vitro model does not detect mitochondrial permeability transition (MPT)-induced toxicity. Another study with a lipopolysaccharide-pre-administered rodent model showed that ischemia/reperfusion induced ROS, sensitized the susceptibility of MPT pore opening and, finally developed drug-induced liver toxicity. Based on this result, the present study investigated the effect of hypoxia/reoxygenation (H/R) treatment mimicking the ischemia/reperfusion on MPT-dependent toxicity, aiming to construct a system that can evaluate MPT by drugs in hepatocytes. Mitochondrial ROS were enhanced by H/R treatment only in the galactose culture condition. Amiodarone, benzbromarone, flutamide and troglitazone which induced MPT pore opening led to hepatocyte death only in combination with H/R and galactose. Moreover, this alteration was significantly suppressed in hepatocytes lacking cyclophilin D. In conclusion, MPT-induced cytotoxicity can be detected by activating mitochondrial function and H/R. This cell-based assay system could evaluate MPT induced-cytotoxicity by drugs, besides RCI and ROS induction.