MicroRNAs in Drug-induced Liver Injury

Exosomal miR-122, miR-128, miR-200, miR-298, and miR-342 as novel diagnostic biomarkers in NAFL/NASH: Impact of LPS/TLR-4/FoxO3 pathway

Nonalcoholic fatty liver disease (NAFLD) is a common liver disorder affecting a quarter of the global residents. Progression of NAFL into nonalcoholic steatohepatitis (NASH) may cause cirrhosis, liver cancer, and failure. Gut microbiota imbalance causes microbial components translocation into the circulation, triggering liver inflammation and NASH-related fibrosis. MicroRNAs (miRNAs) regulate gene expression via repressing target genes. Exosomal miRNAs are diagnostic and prognostic biomarkers for NAFL and NASH liver damage. Our work investigated the role of the gut microbiota in NAFLD pathogenesis via the lipopolysaccharide/toll-like receptor 4/Forkhead box protein O3 (LPS/TLR-4/FoxO3) pathway and certain miRNAs as noninvasive biomarkers for NAFL or its development to NASH. miRNA expression levels were measured using quantitative reverse transcription polymerase chain reaction (qRT-PCR) in 50 NAFL patients, 50 NASH patients, and 50 normal controls. Plasma LPS, TLR-4, adiponectin, peroxisome proliferator-activated receptor γ (PPAR-γ), and FoxO3 concentrations were measured using enzyme-linked immunosorbent assay (ELISA). In NAFL and NASH patients, miR-122, miR-128, FoxO3, TLR-4, LPS, and PPAR-γ were upregulated while miR-200, miR-298, miR-342, and adiponectin were downregulated compared with the normal control. The examined miRNAs might distinguish NAFL and NASH patients from the normal control using receiver operating characteristic analysis. Our study is the first to examine these miRNAs in NAFLD. Our findings imply that these are potentially promising biomarkers for noninvasive early NAFL diagnosis and NASH progression. Understanding the LPS/TLR-4/FoxO3 pathway involvement in NAFL/NASH pathogenesis may aid disease management.

Network Pharmacology Prediction and Experimental Validation of Ferulic Acid’s Protective Effects against Diclofenac‐Induced Liver Injury

Despite being one of the most consumed analgesics worldwide, liver injury is an adverse effect of diclofenac (DF). In pursuit of reliable hepatoprotective natural remedies, this study aimed to investigate the potential protective effect of ferulic acid (FA) and its mechanism against DF‐induced liver injury. Various network databases and datasets were used to collect targets corresponding to FA and DF‐induced liver injury. Enrichment analyses of common targets were performed, a protein‐protein interaction (PPI) network was constructed, the hub genes were identified, and the upstream miRNA interacting with the top hub gene was later predicted. A DF‐induced liver injury rat model was established to verify FA’s protective effects, and the selected hub gene expression level with its upstream regulatory miRNA and a downstream set of targets was examined to elucidate the underlying mechanism. A total of 18 genes were identified as potential targets of FA to protect against DF‐induced liver injury. Data from the enrichment and PPI analyses and the prediction of the upstream miRNAs indicated that the most worthwhile pair to study was miR‐296‐5p/Jun. In vivo findings showed that coadministration of FA significantly reduced the DF‐induced alterations in the liver function indices, oxidative stress, and liver histology. Mechanistically, FA downregulated the expression of Jun, Bim, Bax, Casp3, IL‐1β, IL‐6, and TNF‐α, whereas it upregulated the expression of rno‐miR‐296‐5p and Bcl2. In conclusion, combining network pharmacology and an in vivo study revealed that miR‐296‐5p/Jun axis could mediate the mitigative effect of FA against DF‐induced liver injury.

Mechanism of idiosyncratic drug induced liver injury (DILI): unresolved basic issues

Clinical features of idiosyncratic drug induced liver injury (DILI) are well described in cases that have been assessed for causality using the Roussel Uclaf Causality Assessment Method (RUCAM), but our understanding of the mechanistic steps leading to injury is fragmentary. The difficulties describing mechanistic events can be traced back to the lack of an animal model of experimental idiosyncratic DILI that can mimic the genetic requirements of human idiosyncratic DILI. However, immune tolerance plays a dominant role in the immune response of the liver, and impairment of immune tolerance with immune checkpoint inhibitors increases DILI in both humans and animals. This may provide one method to study the individual steps involved. In general. the human DILI liver is a secret keeper providing little insight into what occurs in the diseased organ. Sufficient evidence exists that most idiosyncratic cases are mediated by the adaptive immune system, which depends on stimulation of the innate immune system, but the triggering factors are unknown. It is attractive to hypothesize that the gut microbiome plays a role; however, it is very difficult to study. Similarly, exosomes are likely to play an important role in communication between hepatic cells and the immune system, but there is a lack of data on blood exosomes in affected patients. Reactive metabolites are likely to play an important role. This is supported by the current analysis, which revealed an association between metabolism by cytochrome P450 and drugs most commonly involved in causing idiosyncratic DILI with causality verified by RUCAM. Circumstantial evidence suggests that reactive oxygen species (ROS) generated by cytochrome P450 could be responsible for the initial steps of injury, but details are unknown. In conclusion, most of the mechanistic steps leading to idiosyncratic DILI remain unclear.

Circulating microRNAs as non-invasive biomarkers for hepatitis B virus liver fibrosis

Viruses can alter the expression of host microRNAs (MiRNA s) and modulate the immune response during a persistent infection. The dysregulation of host MiRNA s by hepatitis B virus (HBV) contributes to the proinflammatory and profibrotic changes within the liver. Multiple studies have documented the differential regulation of intracellular and circulating MiRNA s during different stages of HBV infection. Circulating MiRNA s found in plasma and/or extracellular vesicles can integrate data on viral-host interactions and on the associated liver injury. Hence, the detection of circulating MiRNA s in chronic HBV hepatitis could offer a promising alternative to liver biopsy, as their expression is associated with HBV replication, the progression of liver fibrosis, and the outcome of antiviral treatment. The current review explores the available data on miRNA involvement in HBV pathogenesis with an emphasis on their potential use as biomarkers for liver fibrosis.

Diagnostic Biomarkers in Liver Injury by Drugs, Herbs, and Alcohol: Tricky Dilemma after EMA Correctly and Officially Retracted Letter of Support

Liver injuries caused by the use of exogenous compounds such as drugs, herbs, and alcohol are commonly well diagnosed using laboratory tests, toxin analyses, or eventually reactive intermediates generated during metabolic degradation of the respective chemical in the liver and subject to covalent binding by target proteins. Conditions are somewhat different for idiosyncratic drug induced liver injury (DILI), for which metabolic intermediates as diagnostic aids are rarely available. Although the diagnosis of idiosyncratic DILI can well be established using the validated, liver specific, structured, and quantitative RUCAM (Roussel Uclaf Causality Assessment Method), there is an ongoing search for new diagnostic biomarkers that could assist in and also confirm RUCAM-based DILI diagnoses. With respect to idiosyncratic DILI and following previous regulatory letters of recommendations, selected biomarkers reached the clinical focus, including microRNA-122, microRNA-192, cytokeratin analogues, glutamate dehydrogenase, total HMGB-1 (High Mobility Group Box), and hyperacetylated HMGB-1 proteins. However, the new parameters total HMGB-1, and even more so the acetylated HMGB-1, came under critical scientific fire after misconduct at one of the collaborating partner centers, leading the EMA to recommend no longer the exploratory hyperacetylated HMGB1 isoform biomarkers in clinical studies. The overall promising nature of the recommended biomarkers was considered by EMA as highly dependent on the outstanding results of the now incriminated biomarker hyperacetylated HMGB-1. The EMA therefore correctly decided to officially retract its Letter of Support affecting all biomarkers listed above. New biomarkers are now under heavy scrutiny that will require re-evaluations prior to newly adapted recommendations. With Integrin beta 3 (ITGB3), however, a new diagnostic biomarker may emerge, possibly being drug specific but tested in only 16 patients; due to substantial remaining uncertainties, final recommendations would be premature. In conclusion, most of the currently recommended new biomarkers have lost regulatory support due to scientific misconduct, requiring now innovative approaches and re-evaluation before they can be assimilated into clinical practice.

MicroRNA expression profiling of intestinal mucosa tissue predicts multiple crucial regulatory molecules and signaling pathways for gut barrier dysfunction of AIDS patients

Human immunodeficiency virus‑1 (HIV‑1) infection severely damages the gut‑associated lymphoid tissue (GALT), the immune system and the gut barrier, which leads to accelerating the disease progression for patients with acquired immune deficiency syndrome (AIDS). Dysregulation of microRNAs (miRNAs) may contribute to this process. However, few studies have investigated the importance of miRNAs in AIDS pathogenesis and progression. The whole miRNA profile of patients with HIV infection from southwest P.R. China and the mode of interaction between HIV‑1 and miRNAs remains to be elucidated. Colon mucosal samples were collected from HIV+ patients and HIV‑ healthy individuals, miRNAs were isolated and subjected to array hybridization in the present study. A total of 476 human and virus‑derived microRNAs were significantly altered in the HIV+ group when compared with the control group (P<0.05), which may be involved in the progression to AIDS. Target genes of the significantly altered miRNAs were predicted using the TargetScan, miRbase and miRanda databases and the 10 shared target genes of upregulated miRNAs and the 391 target genes of downregulated miRNAs were selected. As only 10 target genes were predicted for upregulated miRNAs, subsequent GO and KEGG pathway analyses were focused on the 391 target genes of the downregulated miRNAs. The findings of the present study identified a series of crucial pathways, including cell‑extracellular matrix interaction and chemokine regulation, which indicated close affinity with CD4+ T cell activation. These pathways, involving genes such as integrin α5, led to a gut barrier dysfunction of patients with HIV. Important miRNAs include hsa‑miRNA‑32‑5p, hsa‑miRNA‑195‑5p, hsa‑miRNA‑20b‑5p, hsa‑miRNA‑590‑5p. The expression levels of the miRNAs and their target genes were confirmed using RT‑qPCR. Taking into previous observations, the findings of the present study identified the importance of miRNAs for regulating gut barrier dysfunction via multiple regulatory molecules and signaling pathways, which elucidated the underlying molecular mechanism of gut barrier dysfunction in patients with HIV.

Drug Induced Liver Injury: Can Biomarkers Assist RUCAM in Causality Assessment?

Drug induced liver injury (DILI) is a potentially serious adverse reaction in a few susceptible individuals under therapy by various drugs. Health care professionals facing DILI are confronted with a wealth of drug-unrelated liver diseases with high incidence and prevalence rates, which can confound the DILI diagnosis. Searching for alternative causes is a key element of RUCAM (Roussel Uclaf Causality Assessment Method) to assess rigorously causality in suspected DILI cases. Diagnostic biomarkers as blood tests would be a great help to clinicians, regulators, and pharmaceutical industry would be more comfortable if, in addition to RUCAM, causality of DILI can be confirmed. High specificity and sensitivity are required for any diagnostic biomarker. Although some risk factors are available to evaluate liver safety of drugs in patients, no valid diagnostic or prognostic biomarker exists currently for idiosyncratic DILI when a liver injury occurred. Identifying a biomarker in idiosyncratic DILI requires detailed knowledge of cellular and biochemical disturbances leading to apoptosis or cell necrosis and causing leakage of specific products in blood. As idiosyncratic DILI is typically a human disease and hardly reproducible in animals, pathogenetic events and resulting possible biomarkers remain largely undisclosed. Potential new diagnostic biomarkers should be evaluated in patients with DILI and RUCAM-based established causality. In conclusion, causality assessment in cases of suspected idiosyncratic DILI is still best achieved using RUCAM since specific biomarkers as diagnostic blood tests that could enhance RUCAM results are not yet available.

Traditional Chinese Medicine (TCM) and Herbal Hepatotoxicity: RUCAM and the Role of Novel Diagnostic Biomarkers Such as MicroRNAs

Background: Traditional Chinese Medicine (TCM) with its focus on herbal use is popular and appreciated worldwide with increased tendency, although its therapeutic efficacy is poorly established for most herbal TCM products. Treatment was perceived as fairly safe but discussions emerged more recently as to whether herb induced liver injury (HILI) from herbal TCM is a major issue; Methods: To analyze clinical and case characteristics of HILI caused by herbal TCM, we undertook a selective literature search in the PubMed database with the search items Traditional Chinese Medicine, TCM, alone and combined with the terms herbal hepatotoxicity or herb induced liver injury; Results: HILI caused by herbal TCM is rare and similarly to drugs can be caused by an unpredictable idiosyncratic or a predictable intrinsic reaction. Clinical features of liver injury from herbal TCM products are variable, and specific diagnostic biomarkers such as microsomal epoxide hydrolase, pyrrole-protein adducts, metabolomics, and microRNAs are available for only a few TCM herbs. The diagnosis is ascertained if alternative causes are validly excluded and causality levels of probable or highly probable are achieved applying the liver specific RUCAM (Roussel Uclaf Causality Assessment Method) as the most commonly used diagnostic tool worldwide. Case evaluation may be confounded by inappropriate or lacking causality assessment, poor herbal product quality, insufficiently documented cases, and failing to exclude alternative causes such as infections by hepatotropic viruses including hepatitis E virus infections; Conclusion: Suspected cases of liver injury from herbal TCM represent major challenges that deserve special clinical and regulatory attention to improve the quality of case evaluations and ascertain patients' safety and benefit.

MicroRNAs as Biomarkers for Liver Disease and Hepatocellular Carcinoma

Serum levels of liver enzymes, such as alanine transaminase, aspartate transaminase, and α-fetoprotein, provide insight into liver function and are used during treatment of liver disease, but such information is limited. In the case of hepatocellular carcinoma (HCC), which is often not detected until an advanced stage, more sensitive biomarkers may help to achieve earlier detection. Serum also contains microRNAs, a class of small non-coding RNAs that play an important role in regulating gene expression. miR-122 is specific to the liver and correlates strongly with liver enzyme levels and necroinflammatory activity, and other microRNAs are correlated with the degree of fibrosis. miR-122 has also been found to be required for hepatitis C virus (HCV) infection, whereas other microRNAs have been shown to play antiviral roles. miR-125a-5p and miR-1231 have been shown to directly target hepatitis B virus (HBV) transcripts, and others are up- or down-regulated in infected individuals. MicroRNA profiles also differ in the case of HBV and HCV infection as well as between HBeAg-positive and negative patients, and in patients with occult versus active HBV infection. In such patients, monitoring of changes in microRNA profiles might provide earlier warning of neoplastic changes preceding HCC.