Biochemical mechanisms of nephrotoxicity: application for metabolomics

This review describes biochemical pathways of nephrotoxicity and the application of metabolic biomarkers as they relate to nephrotoxicity. Specific and sensitive biomarkers constitute the missing link in the continuum of exposure to toxins and susceptibility, disease development and possible therapeutic intervention. Important requirements for biomarker development are a detailed understanding of biochemical pathways involved in nephrotoxicity, minimal invasiveness and capacity to screen large at-risk populations. Lastly, possible biomarker candidates should be organ specific and equally applicable in preclinical drug testing as well as in clinical care of patients. This review discusses four major metabolic pathways associated with disturbed renal homeostasis: i) direct metabolic evidence of abnormal excretion of endogenous metabolites; ii) disturbances in kidney osmolarity and renal osmolyte homeostasis; iii) impaired energy state followed by dysregulation of glucose, fatty acid and ketone body metabolism; and iv) oxidative stress in renal tissues. Each of these pathways can be monitored by specific surrogate markers in urine and blood using modern metabolomics technologies.     

尿液NGAL作为药物诱导急性肾毒性生物标志物的研究进展

寻找能早期、灵敏、特异地诊断肾毒性的新型生物标志物已成为目前药物临床前研究的热点。大量研究发现尿液中性粒细胞明胶酶相关脂质运载蛋白（NGAL）对肾损伤的诊断效能优于传统生物标志物血清肌酐和尿素氮。2018年尿液NGAL获得了美国食品药品监督管理局的批准，可用于I期临床试验中药物对肾小管损伤作用的监测，但其在临床前试验中的应用和推广仍有待进一步研究。就NGAL特性、作为药物诱导急性肾损伤生物标志物研究进展及其应用面临的挑战进行综述，以期为NGAL在我国新药研发中对急性肾毒性评价的应用奠定基础。     

Metabolomic approaches in the discovery of potential urinary biomarkers of drug-induced liver injury (DILI)

Drug-induced liver injury (DILI) is a major safety issue during drug development, as well as the most common cause for the withdrawal of drugs from the pharmaceutical market. The identification of DILI biomarkers is a labor-intensive area. Conventional biomarkers are not specific and often only appear at significant levels when liver damage is substantial. Therefore, new biomarkers for early identification of hepatotoxicity during the drug discovery process are needed, thus resulting in lower development costs and safer drugs. In this sense, metabolomics has been increasingly playing an important role in the discovery of biomarkers of liver damage, although the characterization of the mechanisms of toxicity induced by xenobiotics remains a huge challenge. These new-generation biomarkers will offer obvious benefits for the pharmaceutical industry, regulatory agencies, as well as a personalized clinical follow-up of patients, upon validation and translation into clinical practice or approval for routine use. This review describes the current status of the metabolomics applied to the early diagnosis and prognosis of DILI and in the discovery of new potential urinary biomarkers of liver injury.     

Comparison of the Mesoscale Discovery and Luminex multiplex platforms for measurement of urinary biomarkers in a cisplatin rat kidney injury model

IntroductionIn the past years several new urinary nephrotoxicity biomarkers have been qualified for use in preclinical studies by the FDA and EMA. Subsequently, kits have been developed to measure these urinary biomarkers on multiplex platforms such as the electro-chemiluminescent based immunoassay from MesoScale Discovery (MSD) and the bead-based immunoassay using Luminex xMAP technology (LMX). The aim of the present study was to compare the two multiplex platforms with respect to the capability of their qualified urinary biomarker panels to measure an increase of these biomarkers relative to histopathological changes in an animal model of nephrotoxicity.MethodsFor comparison of the two platforms we used urine samples from a study with the well-characterized nephrotoxin cisplatin (Cp) in male Wistar rats. The following five biomarkers were measured on both platforms: glutathione S-transferase α (αGST), clusterin (CLU), kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL, a.k.a. lipocalin-2) and osteopontin (OPN). The measurements were compared with respect to both the fold increase observed for each biomarker and the absolute concentrations measured in relation to traditional endpoints for nephrotoxicity in clinical pathology and histopathology.ResultsThe platform comparison revealed the expected increases of urinary biomarkers after Cp treatment with similar results at the fold change level enabling consistent detection of kidney injury. The comparison of the absolute concentrations of biomarkers measured in the two platforms showed differences, the extent of which was analyte-dependent.DiscussionBy comparison of two widely used multiplex platforms, MSD and LMX, for the detection of renal toxicity biomarkers in urine, we observed the expected increases of these biomarkers in response to Cp administration. Depending on the marker, significant differences could be found when comparing the absolute concentrations thus suggesting that baseline levels for each platform will have to be set separately.     

Monitoring kidney safety in drug development: emerging technologies and their implications

Drug-induced kidney injury is a serious and not uncommon adverse event which needs to be considered during drug development. The current standards used to monitor kidney function, such as blood urea nitrogen and serum creatinine, are late indicators of kidney injury and thus do not allow for timely intervention before loss of function. Improving the diagnosis and monitoring of kidney damage goes hand-in-hand with the identification of new biomarkers and the development of technologies that enable their sensitive and specific measurements. In order to move beyond restriction to internal company decisions, every entity that demonstrates the qualities of a biomarker must gain acceptance by health authorities if it is to be used for regulatory decision making in preclinical studies and clinical trials. This review focuses on the most promising achievements of new technologies applied to monitoring drug-induced nephrotoxicity (eg, gene expression, imaging, in vitro screening, protein assays) and on the use and implications of peripheral biomarkers such as the urinary protein biomarkers glutathione S-transferase-alpha, N-acetyl-beta-d-glucosaminidase, total protein, cystatin C, beta2-microglobulin, KIM-1, lipocalin-2 and serum cystatin C. Finally, the associated regulatory processes for use in clinics are also discussed.     

代谢物组学在肾病研究中的应用

肾功能经典生化指标缺乏足够的灵敏度和专属性,明显滞后于肾病的发生,在预测肾病进程风险及指导治疗干预方面尚有欠缺。因此,筛选更灵敏、专属的肾病相关生物标志物具有重要意义。代谢物组学以其独特的研究思路和技术优势,在肾病的临床诊断、预后评估和个体化治疗方面初步显示出应用潜能。本文就代谢物组学相关技术在肾病研究领域的最新进展和应用前景做简要综述。     

Identification of biomarkers to diagnose diseases and find adverse drug reactions by metabolomics

Metabolomics has been widely used for investigating the biological functions of disease expression and has the potential to discover biomarkers in circulating biofluids or tissue extracts that reflect in phenotypic changes. Metabolic profiling has advantages because of the use of unbiased techniques, including multivariate analysis, and has been applied in pharmacological studies to predict therapeutic and adverse reactions of drugs, which is called pharmacometabolomics (PMx). Nuclear magnetic resonance (NMR)- and mass spectrometry (MS)-based metabolomics has contributed to the discovery of recent disease biomarkers; however, the optimal strategy for the study purpose must be selected from many established protocols, methodologies and analytical platforms. Additionally, information on molecular localization in tissue is essential for further functional analyses related to therapeutic and adverse effects of drugs in the process of drug development. MS imaging (MSI) is a promising technology that can visualize molecules on tissue surfaces without labeling and thus provide localized information. This review summarizes recent uses of MS-based global and wide-targeted metabolomics technologies and the advantages of the MSI approach for PMx and highlights the PMx technique for the biomarker discovery of adverse drug effects.     

Potential of metabolomics in preclinical and clinical drug development

Metabolomics is an upcoming technology system which involves detailed experimental analysis of metabolic profiles. Due to its diverse applications in preclinical and clinical research, it became an useful tool for the drug discovery and drug development process. This review covers the brief outline about the instrumentation and interpretation of metabolic profiles. The applications of metabolomics have a considerable scope in the pharmaceutical industry, almost at each step from drug discovery to clinical development. These include finding drug target, potential safety and efficacy biomarkers and mechanisms of drug action, the validation of preclinical experimental models against human disease profiles, and the discovery of clinical safety and efficacy biomarkers. As we all know, nowadays the drug discovery and development process is a very expensive, and risky business. Failures at any stage of drug discovery and development process cost millions of dollars to the companies. Some of these failures or the associated risks could be prevented or minimized if there were better ways of drug screening, drug toxicity profiling and monitoring adverse drug reactions. Metabolomics potentially offers an effective route to address all the issues associated with the drug discovery and development.     

Metabolomics for early detection of drug-induced kidney injury: review of the current status

The identification of biomarkers of drug-induced kidney injury is an area of intensive focus in drug development. Traditional markers of renal function, including blood urea nitrogen and serum creatinine, are not region-specific and only increase significantly after substantial kidney injury. Therefore, more sensitive markers of kidney injury are needed. The ideal biomarkers will identify nephrotoxicity early in the drug-discovery process, resulting in decreased development costs and safer drugs. Metabolomics, the study of the small biochemicals present in a biological sample, has become a promising player in the nephrotoxicity arena. In this review, we describe the current status of the identification of metabolic biomarkers for drug-induced kidney toxicity screening. Many of these markers have been confirmed across multiple studies and can detect nephrotoxicity earlier than the traditional clinical chemistry and histopathology methods. Upon further validation, such markers will offer clear benefits for the pharmaceutical industry and regulatory agencies.     

Mass Spectrometry Strategies for Clinical Metabolomics and Lipidomics in Psychiatry,Neurology, and Neuro-Oncology

Metabolomics research has the potential to provide biomarkers for the detection of disease, for subtyping complex disease populations, for monitoring disease progression and therapy, and for defining new molecular targets for therapeutic intervention. These potentials are far from being realized because of a number of technical, conceptual, financial, and bioinformatics issues. Mass spectrometry provides analytical platforms that address the technical barriers to success in metabolomics research; however, the limited commercial availability of analytical and stable isotope standards has created a bottleneck for the absolute quantitation of a number of metabolites. Conceptual and financial factors contribute to the generation of statistically under-powered clinical studies, whereas bioinformatics issues result in the publication of a large number of unidentified metabolites. The path forward in this field involves targeted metabolomics analyses of large control and patient populations to define both the normal range of a defined metabolite and the potential heterogeneity (eg, bimodal) in complex patient populations. This approach requires that metabolomics research groups, in addition to developing a number of analytical platforms, build sufficient chemistry resources to supply the analytical standards required for absolute metabolite quantitation. Examples of metabolomics evaluations of sulfur amino-acid metabolism in psychiatry, neurology, and neuro-oncology and of lipidomics in neurology will be reviewed.