Single-cell RNA sequencing to reveal non-parenchymal cell heterogeneity and immune network of acetaminophen-induced liver injury in mice

The role of non-parenchymal cells (NPCs) in the early phase of acetaminophen (APAP)-induced liver injury (AILI) remains unclear. Therefore, single-cell sequencing (scRNA-seq) was performed to explore the heterogeneity and immune network of NPCs in the livers of mice with AILI. Mice were challenged with saline, 300 mg/kg APAP, or 750 mg/kg APAP (n = 3 for each group). After 3 h, the liver samples were collected, digested, and subjected to scRNA-seq. Immunohistochemistry and immunofluorescence were performed to confirm the expression of Makorin ring finger protein 1 (Mkrn1). We identified 14 distinct cell subtypes among the 120,599 cells. A variety of NPCs were involved, even in the early stages of AILI, indicating highly heterogeneous transcriptome dynamics. Cholangiocyte cluster 3, which had high deleted in malignant brain tumors 1 (Dmbt1) expression, was found to perform drug metabolism and detoxification functions. Liver sinusoidal endothelial cells exhibited fenestrae loss and angiogenesis. Macrophage cluster 1 displayed a M1 polarization phenotype, whereas cluster 3 tended to exhibit M2 polarization. Kupffer cells (KCs) exhibited pro-inflammatory effects due to the high expression of Cxcl2. qRT-PCR and western blotting verified that the LIFR-OSM axis might promote the activation of MAPK signaling pathway in RAW264.7 macrophages. Mkrn1 was highly expressed in the liver macrophages of AILI mice and AILI patients. Interaction patterns between macrophages/KCs and other NPCs were complex and diverse. NPCs were highly heterogeneous and were involved in the immune network during the early phase of AILI. In addition, we propose that Mkrn1 may serve as a potential biomarker of AILI.

[Genetic susceptibility to drug-induced liver injury]

Drug-induced liver injury (DILI) risk prediction, diagnosis establishment, clinical management, and all other aspects are facing great challenges. Although the current understanding of its pathogenesis is still incomplete, research over the past 20 years has shown that genetic susceptibility may play an important role in the occurrence and development of DILI. In recent years, pharmacogenomics studies have further revealed the association between human leukocyte antigen (HLA) genes, some non-HLA genes, and hepatotoxicity from certain drugs. However, due to the lack of well-designed, prospective, large-sample cohort validation and low positive predictive values, there may still be some way to go before the current results can be truly translated into clinical practice for precise prediction and prevention of DILI risk.

[Statin-related drug-induced liver injury]

Statins are a kind of prescription drug that is widely used to treat hyperlipidemia, coronary artery disease, and other atherosclerotic diseases. A common side effect of statin use is a mild rise in liver aminotransferases, which occurs in less than 3% of patients. Statin-related liver injury is most commonly caused by atorvastatin and simvastatin, but severe liver injury is uncommon. Therefore, understanding and evaluating hepatotoxicity and weighing the benefits and risks is of great significance to better realize the protective effect of statins.