Cyclosporin A induced toxicity in mouse liver slices is only slightly aggravated by Fxr-deficiency and co-occurs with upregulation of pro-inflammatory genes and downregulation of genes involved in mitochondrial functions

Obeticholic Acid Inhibit Mitochondria Dysfunction Via Regulating ERK1/2-DRP Pathway to Exert Protective Effect on Lipopolysaccharide-Induced Myocardial Injury

Farnesoid X receptor (FXR) plays critical regulatory roles in cardiovascular physiology/pathology. However, the role of FXR agonist obeticholic acid (OCA) in sepsis-associated myocardial injury and underlying mechanisms remain unclear. C57BL/6J mice are treated with OCA before lipopolysaccharide (LPS) administration. The histopathology of the heart and assessment of FXR expression and mitochondria function are performed. To explore the underlying mechanisms, H9c2 cells, and primary cardiomyocytes are pre-treated with OCA before LPS treatment, and extracellular signal-regulated protein kinase (ERK) inhibitor PD98059 is used. LPS-induced myocardial injury in mice is significantly improved by OCA pretreatment. Mechanistically, OCA pretreatment decreased reactive oxygen species (ROS) levels and blocked the loss of mitochondrial membrane potential (ΔΨm) in cardiomyocytes. The expression of glutathione peroxidase 1 (GPX1), superoxide dismutase 1 (SOD1), superoxide dismutase 2 (SOD2), and nuclear factor erythroid 2-related factor 2 (NRF-2) increased in the case of OCA pretreatment. In addition, OCA improved mitochondria respiratory chain with increasing Complex I expression and decreasing cytochrome C (Cyt-C) diffusion. Moreover, OCA pretreatment inhibited LPS-induced mitochondria dysfunction via suppressing ERK1/2-DRP signaling pathway. FXR agonist OCA inhibits LPS-induced mitochondria dysfunction via suppressing ERK1/2-DRP signaling pathway to protect mice against LPS-induced myocardial injury.

Time-course cross-species transcriptomics reveals conserved hepatotoxicity pathways induced by repeated administration of cyclosporine A

Cyclosporine A (CsA) has shown efficacy against immunity-related diseases despite its toxicity in various organs, including the liver, emphasizing the need to elucidate its underlying hepatotoxicity mechanism. This study aimed to capture the alterations in genome-wide expression over time and the subsequent perturbations of corresponding pathways across species. Six data from humans, mice, and rats, including animal liver tissue, human liver microtissues, and two liver cell lines exposed to CsA toxic dose, were used. The microtissue exposed to CsA for 10 d was analyzed to obtain dynamically differentially expressed genes (DEGs). Single-time points data at 1, 3, 5, 7, and 28 d of different species were used to provide additional evidence. Using liver microtissue-based longitudinal design, DEGs that were consistently up- or down-regulated over time were captured, and the well-known mechanism involved in CsA toxicity was elucidated. Thirty DEGs that consistently changed in longitudinal data were also altered in 28-d rat in-house data with concordant expression. Some genes (e.g. TUBB2A, PLIN2, APOB) showed good concordance with identified DEGs in 1-d and 7-d mouse data. Pathway analysis revealed up-regulations of protein processing, asparagine N-linked glycosylation, and cargo concentration in the endoplasmic reticulum. Furthermore, the down-regulations of pathways related to biological oxidations and metabolite and lipid metabolism were elucidated. These pathways were also enriched in single-time-point data and conserved across species, implying their biological significance and generalizability. Overall, the human organoids-based longitudinal design coupled with cross-species validation provides temporal molecular change tracking, aiding mechanistic elucidation and biologically relevant biomarker discovery.

Effects of Yinzhihuang on Alleviating Cyclosporine A-Induced Cholestatic Liver Injury via Farnesoid X Receptor-Mediated Regulation of Transporters and Enzymes in Vitro and in Vivo

Yinzhihuang (YZH), a traditional Chinese medicine prescription, was widely used to treat cholestasis. Cholestatic liver injury limited the use of the immunosuppressive drug cyclosporine A (CsA) in preventing organ rejection after solid organ transplantation. Clinical evidences suggested that YZH could enhance bile acids and bilirubin clearance, providing a potential therapeutic strategy against CsA-induced cholestasis. Nevertheless, it remains unclear whether YZH can effectively alleviate CsA-induced cholestatic liver injury, as well as the molecular mechanisms responsible for its hepatoprotective effects. The purpose of the present study was to investigate the hepatoprotective effects of YZH on CsA-induced cholestatic liver injury and explore its molecular mechanisms in vivo and vitro. The results demonstrated that YZH significantly improved the CsA-induced cholestatic liver injury and reduced the level of liver function markers in serum of Sprague-Dawley (SD) rats. Targeted protein and gene analysis indicated that YZH increased bile acids and bilirubin efflux into bile through the regulation of multidrug resistance-associated protein 2 (Mrp2), bile salt export pump (Bsep), sodium taurocholate cotransporting polypeptide (Ntcp) and organic anion transporting polypeptide 2 (Oatp2) transport systems, as well as upstream nuclear receptors farnesoid X receptor (Fxr). Moreover, YZH modulated enzymes involved in bile acids synthesis and bilirubin metabolism including Cyp family 7 subfamily A member 1 (Cyp7a1) and uridine 5'-diphosphate (UDP) glucuronosyltransferase family 1 member A1 (Ugt1a1). Furthermore, the active components geniposidic acid, baicalin and chlorogenic acid exerted regulated metabolic enzymes and transporters in LO2 cells. In conclusion, YZH may prevent CsA-induced cholestasis by regulating the transport systems, metabolic enzymes, and upstream nuclear receptors Fxr to restore bile acid and bilirubin homeostasis. These findings highlight the potential of YZH as a therapeutic intervention for CsA-induced cholestasis and open avenues for further research into its clinical applications.

Mitochondrial regulatory mechanisms in spinal cord injury: A narrative review

Spinal cord injury is a severe central nervous system injury that results in the permanent loss of motor, sensory, and autonomic functions below the level of injury with limited recovery. The pathological process of spinal cord injury includes primary and secondary injuries, characterized by a progressive cascade. Secondary injury impairs the ability of the mitochondria to maintain homeostasis and leads to calcium overload, excitotoxicity, and oxidative stress, further exacerbating the injury. The defective mitochondrial function observed in these pathologies accelerates neuronal cell death and inhibits regeneration. Treatment of spinal cord injury by preserving mitochondrial biological function is a promising, although still underexplored, therapeutic strategy. This review aimed to explore mitochondrial-based therapeutic advances after spinal cord injury. Specifically, it briefly describes the characteristics of spinal cord injury. It then broadly discusses the drugs used to protect the mitochondria (e.g., cyclosporine A, acetyl-L-carnitine, and alpha-tocopherol), phenomena associated with mitochondrial damage processes (e.g., mitophagy, ferroptosis, and cuproptosis), mitochondrial transplantation for nerve cell regeneration, and innovative mitochondrial combined protection therapy.

Mitochondrial-Based Therapeutics for the Treatment of Spinal Cord Injury: Mitochondrial Biogenesis as a Potential Pharmacological Target

Spinal cord injury (SCI) is characterized by an initial trauma followed by a progressive cascade of damage referred to as secondary injury. A hallmark of secondary injury is vascular disruption leading to vasoconstriction and decreased oxygen delivery, which directly reduces the ability of mitochondria to maintain homeostasis and leads to loss of ATP-dependent cellular functions, calcium overload, excitotoxicity, and oxidative stress, further exacerbating injury. Restoration of mitochondria dysfunction during the acute phases of secondary injury after SCI represents a potentially effective therapeutic strategy. This review discusses the past and present pharmacological options for the treatment of SCI as well as current research on mitochondria-targeted approaches. Increased antioxidant activity, inhibition of the mitochondrial permeability transition, alternate energy sources, and manipulation of mitochondrial morphology are among the strategies under investigation. Unfortunately, many of these tactics address single aspects of mitochondrial dysfunction, ultimately proving largely ineffective. Therefore, this review also examines the unexplored therapeutic efficacy of pharmacological enhancement of mitochondrial biogenesis, which has the potential to more comprehensively improve mitochondrial function after SCI.

Rat precision-cut liver slices predict drug-induced cholestatic injury

Drug-induced cholestasis (DIC) is one of the leading manifestations of drug-induced liver injury (DILI). As the underlying mechanisms for DIC are not fully known and specific and predictive biomarkers and pre-clinical models are lacking, the occurrence of DIC is often only reported when the drug has been approved for registration. Therefore, appropriate models that predict the cholestatic potential of drug candidates and/or provide insight into the mechanism of DIC are highly needed. We investigated the application of rat precision-cut liver slices (PCLS) to predict DIC, using several biomarkers of cholestasis: hepatocyte viability, intracellular accumulation of total as well as individual bile acids and changes in the expression of genes known to play a role in cholestasis. Rat PCLS exposed to the cholestatic drugs chlorpromazine, cyclosporine A and glibenclamide for 48 h in the presence of a 60 μM physiological bile acid (BA) mix reflected various changes associated with cholestasis, such as decrease in hepatocyte viability, accumulation and changes in the composition of BA and changes in the gene expression of Fxr, Bsep and Ntcp. The toxicity of the drugs was correlated with the accumulation of BA, and especially DCA and CDCA and their conjugates, but to a different extent for different drugs, indicating that BA toxicity is not the only cause for the toxicity of cholestatic drugs. Moreover, our study supports the use of several biomarkers to test drugs for DIC. In conclusion, our results indicate that PCLS may represent a physiological and valuable model to identify cholestatic drugs and provide insight into the mechanisms underlying DIC.

Role of farnesoid X receptor in cholestasis

The nuclear receptor farnesoid X receptor (FXR) plays an important role in physiological bile acid synthesis, secretion and transport. Defects of FXR regulation in these processes can cause cholestasis and subsequent pathological changes. FXR regulates the synthesis and uptake of bile acid via enzymes. It also increases bile acid solubility and elimination by promoting conjugation reactions and exports pump expression in cholestasis. The changes in bile acid transporters are involved in cholestasis, which can result from the mutations of transporter genes or acquired dysfunction of transport systems, such as inflammation-induced intrahepatic cholestasis. The modulation function of FXR in extrahepatic cholestasis is not identical to that in intrahepatic cholestasis, but the discrepancy may be reduced over time. In extrahepatic cholestasis, increasing biliary pressure can induce bile duct proliferation and bile infarcts, but the absence of FXR may ameliorate them. This review provides an update on the function of FXR in the regulation of bile acid metabolism, its role in the pathophysiological process of cholestasis and the therapeutic use of FXR agonists.