Use of an animal model to test whether non-alcoholic fatty liver disease increases the risk of idiosyncratic drug-induced liver injury

Impact of Non-Alcoholic Simple Fatty Liver Disease on Antituberculosis Drug-Induced Liver Injury

Objective

To observe the effect of non-alcoholic simple fatty liver disease on drug-induced liver injury caused by tuberculosis.

Methods

We retrospectively analyzed the incidence, characteristics, and risk factors of antituberculosis drug-induced liver injury in 104 patients with initial treatment of tuberculosis complicated with non-alcoholic simple fatty liver disease. The patients were divided into two groups according to whether there was liver injury or not. The differences in age, gender, body mass index (BMI), cholesterol, and triglycerides were studied between the two groups.

Results

Among the 104 patients with initial treatment of tuberculosis complicated with non-alcoholic fatty liver disease, 24 (23%) patients developed a drug-induced liver injury. The remaining 80 (77%) patients did not develop drug-induced liver injury (χ² = 60.308, P < 0.05). In the liver injury group, there were 20 cases of mild liver injury, two cases of moderate liver injury, two cases of severe liver injury, 22 cases of hepatocellular injury, two cases of cholestasis, and no cases of mixed liver injury. The time of abnormal liver function in antituberculosis treatment was 16.42 ± 9.18 days from the beginning of the antituberculosis treatment. There were no significant differences in gender, age, BMI, or triglyceride between the liver injury group and the non-liver injury group (χ² = 2.063, t = 0.179, t = 0.703, t = 1.12, P > 0.05 in all), but there were significant differences in cholesterol (t = 3.08, P < 0.05). By logistic regression analysis, cholesterol was a high-risk factor for liver injury.

Conclusion

Non-alcoholic simple fatty liver disease may increase the risk of antituberculosis drug-induced liver injury.

Idiosyncratic Drug-Induced Liver Injury: Mechanistic and Clinical Challenges

Idiosyncratic drug-induced liver injury (IDILI) remains a significant problem for patients and drug development. The idiosyncratic nature of IDILI makes mechanistic studies difficult, and little is known of its pathogenesis for certain. Circumstantial evidence suggests that most, but not all, IDILI is caused by reactive metabolites of drugs that are bioactivated by cytochromes P450 and other enzymes in the liver. Additionally, there is overwhelming evidence that most IDILI is mediated by the adaptive immune system; one example being the association of IDILI caused by specific drugs with specific human leukocyte antigen (HLA) haplotypes, and this may in part explain the idiosyncratic nature of these reactions. The T cell receptor repertoire likely also contributes to the idiosyncratic nature. Although most of the liver injury is likely mediated by the adaptive immune system, specifically cytotoxic CD8+ T cells, adaptive immune activation first requires an innate immune response to activate antigen presenting cells and produce cytokines required for T cell proliferation. This innate response is likely caused by either a reactive metabolite or some form of cell stress that is clinically silent but not idiosyncratic. If this is true it would make it possible to study the early steps in the immune response that in some patients can lead to IDILI. Other hypotheses have been proposed, such as mitochondrial injury, inhibition of the bile salt export pump, unfolded protein response, and oxidative stress although, in most cases, it is likely that they are also involved in the initiation of an immune response rather than representing a completely separate mechanism. Using the clinical manifestations of liver injury from a number of examples of IDILI-associated drugs, this review aims to summarize and illustrate these mechanistic hypotheses.

Psoralidin, a major component of Psoraleae Fructus, induces inflammasome activation and idiosyncratic liver injury

Idiosyncratic drug-induced liver injury (IDILI) is a rare but potentially fatal disease that is unpredictable and independent of the dose of the drug. Increasing evidence suggests that the majority of IDILI cases are immune-mediated, and the aberrant activation of inflammasome plays a vital role in progression. Psoraleae Fructus (PF), a tonic Chinese medicine, has been able to cause IDILI, but the precise mechanism of hepatotoxicity remains unclear. In this study, eight bioactive compounds involved in PF-induced inflammasome activation were investigated. The results demonstrated that psoralidin activated the inflammasomes followed by secreting caspase-1 and interleukin 1β (IL-1β) in a dose-dependent manner. Interestingly, MCC950, a potent inhibitor of the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, could not entirely suppress the psoralidin-induced inflammasome activation. Moreover, psoralidin significantly induced IL-1β maturation and caspase-1 activation in NLRP3-knockout bone marrow-derived macrophages (BMDMs), suggesting that psoralidin not only activates the NLRP3 inflammasome but also activates other types of inflammasomes. The results also demonstrated that psoralidin activated the inflammasomes by promoting the C-terminal caspase recruitment domain (ASC) oligomerization, and the production of mitochondrial reactive oxygen species (mtROS) is a decisive factor in psoralidin-induced inflammasome activation. Importantly, in vivo data revealed that psoralidin induced hepatic inflammation, increased aminotransferase activity and increased the production of IL-1β and tumor necrosis factor(TNF-α) in a susceptible mouse model of lipopolysaccharide (LPS)-mediated IDILI. In summary, these results confirmed that psoralidin causes IDILI by inducing inflammasome activation. The study suggests that psoralidin is a possible risk factor and is responsible for PF-induced IDILI.

Gynura divaricata exerts hypoglycemic effects by regulating the PI3K/AKT signaling pathway and fatty acid metabolism signaling pathway

OBJECTIVES

The study aimed to examine the anti-diabetic effects of Gynura divaricata (GD) and the underlying mechanism.

METHODS

Information about the chemical compositions of GD was obtained from extensive literature reports. Potential target genes were predicted using PharmMapper and analyzed using Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO). To validate the results from bioinformatics analyses, an aqueous extract of GD was administered to type 2 diabetic rats established by feeding a high-fat and high-sugar diet followed by STZ injection. Key proteins of the PI3K/AKT signaling pathway and fatty acid metabolism signaling pathway were investigated by immunoblotting.

RESULTS

The blood glucose of the rats in the GD treatment group was significantly reduced compared with the model group without treatment. GD also showed activities in reducing the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), and creatinine (CREA). The levels of urine sugar (U-GLU) and urine creatinine (U-CREA) were also lowered after treatment with GD. Bioinformatics analysis showed that some pathways including metabolic pathways, insulin resistance, insulin signaling pathway, PPAR signaling pathway, bile secretion, purine metabolism, etc. may be regulated by GD. Furthermore, GD significantly increased the protein expression levels of PKM1/2, p-AKT, PI3K p85, and GLUT4 in the rat liver. In addition, the expression levels of key proteins in the fatty acid metabolism signaling pathway including AMPK, p-AMPK, PPARα, and CPT1α were significantly upregulated. The anti-apoptotic protein BCL-2/BAX expression ratio in rats was significantly upregulated after GD intervention. These results were consistent with the bioinformatics analysis results.

CONCLUSIONS

Our study suggests that GD can exert hypoglycemic effects in vivo by regulating the genes at the key nodes of the PI3K/AKT signaling pathway and fatty acid metabolism signaling pathway.

Non-alcoholic fatty liver disease is a potential risk factor for liver injury caused by immune checkpoint inhibitor

BACKGROUND AND AIM

Because of their survival benefits, immune checkpoint inhibitors (ICIs) are widely administered to patients with various advanced-stage malignancies. During ICI treatment, drug-induced liver injury (DILI) occasionally occurs. In particular, hepatic immune-related adverse events (irAEs) are rare but serious and fatal. In patients with hepatic irAEs, immediate steroid treatment is generally recommended; however, the risk factors for ICI-associated DILI remain unknown. In the present study, we identified a risk factor for ICI-associated DILI.

METHODS

We retrospectively analyzed 135 patients treated with anti-programmed cell death-1 (PD-1) antibodies, such as nivolumab and pembrolizumab, at Asahikawa Medical University Hospital. We investigated grade ≥ 2 hepatotoxic AEs during anti-PD-1 therapy, and PD-1 inhibitor-associated DILI was then diagnosed according to the Digestive Disease Week Japan (DDW-J) 2004 scale. The risk factors for PD-1 inhibitor-associated DILI were identified by Cox hazard analysis.

RESULTS

Thirty-six patients developed grade ≥ 2 hepatic AEs during anti-PD-1 therapy. Among them, eight patients were diagnosed with PD-1 inhibitor-associated DILI based on the DDW-J 2004 scale. Cox hazard analysis revealed that non-alcoholic fatty liver disease (NAFLD) was a risk factor for PD-1 inhibitor-associated DILI. In addition, we revealed that the outcomes of patients with the DDW-J 2004 score = 3 were improved without steroid treatment.

CONCLUSIONS

NAFLD is a potential risk factor for PD-1 inhibitor-associated DILI based on the DDW-J 2004 scale. The DDW-J 2004 scale might be useful for determining whether steroid treatment is required in patients with PD-1 inhibitor-associated DILI.

Drug-induced liver injury in obesity and nonalcoholic fatty liver disease

Obesity is commonly associated with nonalcoholic fatty liver (NAFL), a benign condition characterized by hepatic lipid accumulation. However, NAFL can progress in some patients to nonalcoholic steatohepatitis (NASH) and then to severe liver lesions including extensive fibrosis, cirrhosis and hepatocellular carcinoma. The entire spectrum of these hepatic lesions is referred to as nonalcoholic fatty liver disease (NAFLD). The transition of simple fatty liver to NASH seems to be favored by several genetic and environmental factors. Different experimental and clinical investigations showed or suggested that obesity and NAFLD are able to increase the risk of hepatotoxicity of different drugs. Some of these drugs may cause more severe and/or more frequent acute liver injury in obese individuals whereas others may trigger the transition of simple fatty liver to NASH or may worsen hepatic lipid accumulation, necroinflammation and fibrosis. This review presents the available information regarding drugs that may cause a specific risk in the context of obesity and NAFLD. These drugs, which belong to different pharmacological classes, include acetaminophen, halothane, methotrexate, rosiglitazone and tamoxifen. For some of these drugs, experimental investigations confirmed the clinical observations and unveiled different pathophysiological mechanisms which may explain why these pharmaceuticals are particularly hepatotoxic in obesity and NAFLD. Because obese people often take several drugs for the treatment of different obesity-related diseases, there is an urgent need to identify the main pharmaceuticals that may cause acute liver injury on a fatty liver background or that may enhance the risk of severe chronic liver disease.