bims-mascan 2021-11-14 papers

bims-mascan

Biomed News

on Mass spectrometry in cancer research

Issue of 2021–11–14
eightteen papers selected by
Giovanny Rodriguez Blanco, University of Edinburgh

Lipid metabolism in cancer progression and therapeutic strategies.
Lipid metabolism reprogramming in renal cell carcinoma.
AdipoAtlas: A reference lipidome for human white adipose tissue.
The Neglected Liaison: Targeting Cancer Cell Metabolic Reprogramming Modifies the Composition of Non-Malignant Populations of the Tumor Microenvironment.
Single Cell Proteomics Using Multiplexed Isobaric Labeling for Mass Spectrometric Analysis.
Fibroblast pyruvate carboxylase is required for collagen production in the tumour microenvironment.
Cysteine Restriction in Murine L929 Fibroblasts as an Alternative Strategy to Methionine Restriction in Cancer Therapy.
UPLC-MS/MS-based plasma lipidomics reveal a distinctive signature in systemic lupus erythematosus patients.
Enantioselective metabolomics by liquid chromatography-mass spectrometry.
Spatially resolved quantification of drug metabolism and efficacy in 3D paper-based tumor mimics.
Development of simultaneous quantitative analysis of tricarboxylic acid cycle metabolites to identify specific metabolites in cancer cells by targeted metabolomic approach.
A Prostate Cancer Proteomics Database for SWATH-MS Based Protein Quantification.
Apoptotic stress-induced FGF signalling promotes non-cell autonomous resistance to cell death.
Fatty acid metabolism in cancer cells - the power of plasticity.
Protocol for the assessment of mTOR activity in mouse primary hepatocytes.
Metabolite Identification Using Infrared Ion Spectroscopy─Novel Biomarkers for Pyridoxine-Dependent Epilepsy.
A Lipidomics Atlas of Selected Sphingolipids in Multiple Mouse Nervous System Regions.
Rapid and sensitive detection of SARS-CoV-2 infection using quantitative peptide enrichment LC-MS analysis.

MedComm (Beijing). 2021 Mar;2(1): 27-59

Lipid metabolism in cancer progression and therapeutic strategies.

Yan Fu, Tiantian Zou, Xiaotian Shen, Peter J Nelson, Jiahui Li, Chao Wu, Jimeng Yang, Yan Zheng, Christiane Bruns, Yue Zhao, Lunxiu Qin, Qiongzhu Dong.

  Dysregulated lipid metabolism represents an important metabolic alteration in cancer. Fatty acids, cholesterol, and phospholipid are the three most prevalent lipids that act as energy producers, signaling molecules, and source material for the biogenesis of cell membranes. The enhanced synthesis, storage, and uptake of lipids contribute to cancer progression. The rewiring of lipid metabolism in cancer has been linked to the activation of oncogenic signaling pathways and cross talk with the tumor microenvironment. The resulting activity favors the survival and proliferation of tumor cells in the harsh conditions within the tumor. Lipid metabolism also plays a vital role in tumor immunogenicity via effects on the function of the noncancer cells within the tumor microenvironment, especially immune-associated cells. Targeting altered lipid metabolism pathways has shown potential as a promising anticancer therapy. Here, we review recent evidence implicating the contribution of lipid metabolic reprogramming in cancer to cancer progression, and discuss the molecular mechanisms underlying lipid metabolism rewiring in cancer, and potential therapeutic strategies directed toward lipid metabolism in cancer. This review sheds new light to fully understanding of the role of lipid metabolic reprogramming in the context of cancer and provides valuable clues on therapeutic strategies targeting lipid metabolism in cancer.

Keywords:  cancer; lipid metabolism; mechanism; microenvironment; therapeutic strategy

DOI:  https://doi.org/10.1002/mco2.27
Cancer Metastasis Rev. 2021 Nov 06.

Lipid metabolism reprogramming in renal cell carcinoma.

Gioia Heravi, Omid Yazdanpanah, Izabela Podgorski, Larry H Matherly, Wanqing Liu.

  Metabolic reprogramming is recognized as a hallmark of cancer. Lipids are the essential biomolecules required for membrane biosynthesis, energy storage, and cell signaling. Altered lipid metabolism allows tumor cells to survive in the nutrient-deprived environment. However, lipid metabolism remodeling in renal cell carcinoma (RCC) has not received the same attention as in other cancers. RCC, the most common type of kidney cancer, is associated with almost 15,000 death in the USA annually. Being refractory to conventional chemotherapy agents and limited available targeted therapy options has made the treatment of metastatic RCC very challenging. In this article, we review recent findings that support the importance of synthesis and metabolism of cholesterol, free fatty acids (FFAs), and polyunsaturated fatty acids (PUFAs) in the carcinogenesis and biology of RCC. Delineating the detailed mechanisms underlying lipid reprogramming can help to better understand the pathophysiology of RCC and to design novel therapeutic strategies targeting this malignancy.

Keywords:  Cholesterol; Free fatty acids; Metabolic reprogramming; PUFA; Renal cell carcinoma

DOI:  https://doi.org/10.1007/s10555-021-09996-w
Cell Rep Med. 2021 Oct 19. 2(10): 100407

AdipoAtlas: A reference lipidome for human white adipose tissue.

Mike Lange, Georgia Angelidou, Zhixu Ni, Angela Criscuolo, Jürgen Schiller, Matthias Blüher, Maria Fedorova.

  Obesity, characterized by expansion and metabolic dysregulation of white adipose tissue (WAT), has reached pandemic proportions and acts as a primer for a wide range of metabolic disorders. Remodeling of WAT lipidome in obesity and associated comorbidities can explain disease etiology and provide valuable diagnostic and prognostic markers. To support understanding of WAT lipidome remodeling at the molecular level, we provide in-depth lipidomics profiling of human subcutaneous and visceral WAT of lean and obese individuals. We generate a human WAT reference lipidome by performing tissue-tailored preanalytical and analytical workflows, which allow accurate identification and semi-absolute quantification of 1,636 and 737 lipid molecular species, respectively. Deep lipidomic profiling allows identification of main lipid (sub)classes undergoing depot-/phenotype-specific remodeling. Previously unanticipated diversity of WAT ceramides is now uncovered. AdipoAtlas reference lipidome serves as a data-rich resource for the development of WAT-specific high-throughput methods and as a scaffold for systems medicine data integration.

Keywords:  LC-MS/MS; ceramides; human white adipose tissue; lipid identification; lipid metabolism; lipidomics; obesity; plasmalogens; semi-absolute lipid quantification; sphingolipids; subcutaneous white adipose tissue; triacylglycerols; visceral white adipose tissue

DOI:  https://doi.org/10.1016/j.xcrm.2021.100407
Cancers (Basel). 2021 Oct 29. pii: 5447. [Epub ahead of print]13(21):

The Neglected Liaison: Targeting Cancer Cell Metabolic Reprogramming Modifies the Composition of Non-Malignant Populations of the Tumor Microenvironment.

Maria Iorio, Nikkitha Umesh Ganesh, Monica De Luise, Anna Maria Porcelli, Giuseppe Gasparre, Ivana Kurelac.

  Metabolic reprogramming is a well-known hallmark of cancer, whereby the development of drugs that target cancer cell metabolism is gaining momentum. However, when establishing preclinical studies and clinical trials, it is often neglected that a tumor mass is a complex system in which cancer cells coexist and interact with several types of microenvironment populations, including endothelial cells, fibroblasts and immune cells. We are just starting to understand how such populations are affected by the metabolic changes occurring in a transformed cell and little is known about the impact of metabolism-targeting drugs on the non-malignant tumor components. Here we provide a general overview of the links between cancer cell metabolism and tumor microenvironment (TME), particularly focusing on the emerging literature reporting TME-specific effects of metabolic therapies.

Keywords:  cancer metabolism; cancer-associated fibroblasts; metabolic reprogramming; tumor microenvironment; tumor-associated macrophages

DOI:  https://doi.org/10.3390/cancers13215447
Methods Mol Biol. 2022 ;2386 113-127

Single Cell Proteomics Using Multiplexed Isobaric Labeling for Mass Spectrometric Analysis.

Ákos Végvári, Jimmy E Rodriguez, Roman A Zubarev.

  Single cell proteomics is an emerging field of bioanalysis allowing one to capture proteome profiles of isolated single cells, which is expected to yield additional biological information in comparison with bulk cell analysis. Mass spectrometry-based methods provide unbiased analysis of detectable proteins limited only by technical parameters, such as sensitivity, which necessitates the development of best-practice workflows. Here, we describe the entire experimental design of single cell proteome analysis, exemplified by cultured A549 lung adenocarcinoma cells treated with an anti-cancer drug (methotrexate) and utilizing tandem mass tag (TMTpro™) labeling strategy for mass spectrometric data acquisition.

Keywords:  A549 human cell line; Chemical proteomics; Clean sample preparation; Mass spectrometry; Methotrexate; Single cell proteomics; TMT-labeling

DOI:  https://doi.org/10.1007/978-1-0716-1771-7_8
Nat Metab. 2021 Nov 11.

Fibroblast pyruvate carboxylase is required for collagen production in the tumour microenvironment.

Simon Schwörer, Natalya N Pavlova, Francesco V Cimino, Bryan King, Xin Cai, Gina M Sizemore, Craig B Thompson.

The aberrant production of collagen by fibroblasts is a hallmark of many solid tumours and can influence cancer progression. How the mesenchymal cells in the tumour microenvironment maintain their production of extracellular matrix proteins as the vascular delivery of glutamine and glucose becomes compromised remains unclear. Here we show that pyruvate carboxylase (PC)-mediated anaplerosis in tumour-associated fibroblasts contributes to tumour fibrosis and growth. Using cultured mesenchymal and cancer cells, as well as mouse allograft models, we provide evidence that extracellular lactate can be utilized by fibroblasts to maintain tricarboxylic acid (TCA) cycle anaplerosis and non-essential amino acid biosynthesis through PC activity. Furthermore, we show that fibroblast PC is required for collagen production in the tumour microenvironment. These results establish TCA cycle anaplerosis as a determinant of extracellular matrix collagen production, and identify PC as a potential target to inhibit tumour desmoplasia.

DOI: https://doi.org/10.1038/s42255-021-00480-x
Int J Mol Sci. 2021 Oct 27. pii: 11630. [Epub ahead of print]22(21):

Cysteine Restriction in Murine L929 Fibroblasts as an Alternative Strategy to Methionine Restriction in Cancer Therapy.

Werner Schmitz, Elena Ries, Corinna Koderer, Maximilian Friedrich Völter, Anna Chiara Wünsch, Mohamed El-Mesery, Kyra Frackmann, Alexander Christian Kübler, Christian Linz, Axel Seher.

  Methionine restriction (MetR) is an efficient method of amino acid restriction (AR) in cells and organisms that induces low energy metabolism (LEM) similar to caloric restriction (CR). The implementation of MetR as a therapy for cancer or other diseases is not simple since the elimination of a single amino acid in the diet is difficult. However, the in vivo turnover rate of cysteine is usually higher than the rate of intake through food. For this reason, every cell can enzymatically synthesize cysteine from methionine, which enables the use of specific enzymatic inhibitors. In this work, we analysed the potential of cysteine restriction (CysR) in the murine cell line L929. This study determined metabolic fingerprints using mass spectrometry (LC/MS). The profiles were compared with profiles created in an earlier work under MetR. The study was supplemented by proliferation studies using D-amino acid analogues and inhibitors of intracellular cysteine synthesis. CysR showed a proliferation inhibition potential comparable to that of MetR. However, the metabolic footprints differed significantly and showed that CysR does not induce classic LEM at the metabolic level. Nevertheless, CysR offers great potential as an alternative for decisive interventions in general and tumour metabolism at the metabolic level.

Keywords:  LC/MS; amino acid analogues; caloric restriction; cancer therapy; cysteine restriction; cysteine synthase inhibitor; homocysteine; mass spectrometry; methionine restriction

DOI:  https://doi.org/10.3390/ijms222111630
MedComm (Beijing). 2021 Jun;2(2): 269-278

UPLC-MS/MS-based plasma lipidomics reveal a distinctive signature in systemic lupus erythematosus patients.

Jiaxi Chen, Chong Liu, Shenyi Ye, Ruyue Lu, Hongguo Zhu, Jiaqin Xu.

  Global lipidomics is of considerable utility for exploring altered lipid profiles and unique diagnostic biomarkers in diseases. We aim to apply ultra-performance liquid chromatography-tandem mass spectrometry to characterize the lipidomics profile in systemic lupus erythematosus (SLE) patients and explore the underlying pathogenic pathways using the lipidomics approach. Plasma samples from 18 SLE patients, 20 rheumatoid arthritis (RA) patients, and 20 healthy controls (HC) were collected. A total of 467 lipids molecular features were annotated from each sample. Orthogonal partial least square-discriminant analysis, K-mean clustering analysis and Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated disrupted lipid metabolism in SLE patients, especially in phospholipid, glycerol, and sphingolipid metabolism. The area under curve (AUC) of lipid metabolism biomarkers was better than SLE inflammation markers that ordinarily used in the clinic. Proposed model of monoglyceride (MG) (16:0), MG (18:0), phosphatidylethanolamine (PE) (18:3-16:0), PE (16:0-20:4), and phosphatidylcholine (PC) (O-16:2-18:3) yielded AUC 1.000 (95% CI, 1.000-1.000), specificity 100% and sensitivity 100% in the diagnosis of SLE from HC. A panel of three lipids molecular PC (18:3-18:1), PE (20:3-18:0), PE (16:0-20:4) permitted to accurately diagnosis of SLE from RA, with AUC 0.921 (95% CI, 0.828-1.000), 70% specificity, and 100% sensitivity. The plasma lipidomics signatures could serve as an efficient and accurate tool for early diagnosis and provide unprecedented insight into the pathogenesis of SLE.

Keywords:  biomarkers; lipidomics; systemic lupus erythematosus

DOI:  https://doi.org/10.1002/mco2.67
J Pharm Biomed Anal. 2022 Jan 05. pii: S0731-7085(21)00541-0. [Epub ahead of print]207 114430

Enantioselective metabolomics by liquid chromatography-mass spectrometry.

Carlos Calderón, Michael Lämmerhofer.

  Metabolomics strives to capture the entirety of the metabolites in a biological system by comprehensive analysis, often by liquid chromatography hyphenated to mass spectrometry. A particular challenge thereby is the differentiation of structural isomers. Common achiral targeted and untargeted assays do not distinguish between enantiomers. This may lead to information loss. An increasing number of publications demonstrate that the enantiomeric ratio of certain metabolites can be meaningful biomarkers of certain diseases emphasizing the importance of introducing enantioselective analytical procedures in metabolomics. In this work, the state-of-the-art in the field of LC-MS based metabolomics is summarized with focus on developments in the recent decade. Methodologies, tagging strategies, workflows and general concepts are outlined. Selected biological applications in which enantioselective metabolomics has documented its usefulness are briefly discussed. In general, targeted enantioselective metabolomics assays are often based on a direct approach using chiral stationary phases (CSP) with polysaccharide derivatives, macrocyclic antibiotics, chiral crown ethers, chiral ion exchangers, donor-acceptor phases as chiral selectors. Rarely, these targeted assays focus on more than 20 analytes and usually are restricted to a certain metabolite class. In a variety of cases, pre-column derivatization of metabolites has been performed, especially for amino acids, to improve separation and detection sensitivity. Triple quadrupole instruments are the detection methods of first choice in targeted assays. Here, issues like matrix effect, absence of blank matrix impair accuracy of results. In selected applications, multiple heart cutting 2D-LC (RP followed by chiral separation) has been pursued to overcome this problem and alleviate bias due to interferences. Non-targeted assays, on the other hand, are based on indirect approach involving tagging with a chiral derivatizing agent (CDA). Besides classical CDAs numerous innovative reagents and workflows have been proposed and are discussed. Thereby, a critical issue for the accuracy is often neglected, viz. the validation of the enantiomeric impurity in the CDA. The majority of applications focus on amino acids, hydroxy acids, oxidized fatty acids and oxylipins. Some potential clinical applications are highlighted.

Keywords:  Amino acid; Chiral derivatizing agent; Chiral separation; Chiral stationary phase; Mass tag; Oxylipin

DOI:  https://doi.org/10.1016/j.jpba.2021.114430
Anal Chim Acta. 2021 Nov 22. pii: S0003-2670(21)00917-X. [Epub ahead of print]1186 339091

Spatially resolved quantification of drug metabolism and efficacy in 3D paper-based tumor mimics.

Tyler S Larson, Gary L Glish, Matthew R Lockett.

  Paper-based cultures are an emerging platform for preparing three-dimensional (3D) tissue- and tumor-like structures. The ability to stack individual sheets of cell-containing paper affords a modular means of assembling structures with defined cellular compositions and microenvironments. These layered stacks are easily separated at the end of an experiment, providing spatially resolved populations of live cells for further analysis. Here we describe a workflow in which cell viability, drug penetration, and drug metabolism are quantified in a spatially resolved manner. Specifically, we mapped the distribution of the drug irinotecan and its bioactive metabolite SN38 in a colorectal cancer cell-containing stacked structure with liquid chromatography-mass spectrometry (LC-MS). This paper provides the first example of a 3D culture platform that quantifies viability and drug metabolism in a spatially resolved manner. Our data show that cells at the bottom of the stack are more drug-resistant than layers in contact with the culture medium, similar to cells in the nutrient-poor center of a proliferating tumor being more drug-resistant than the rapidly dividing cells at its periphery. The powerful combination of quantitative viability and drug metabolism measurements will enable future studies to determine the exact mechanism(s) of drug resistance in different regions of a tumor.

Keywords:  3D culture; Cell analysis; Drug metabolism; In vitro; Mass spectrometry; Viability

DOI:  https://doi.org/10.1016/j.aca.2021.339091
Biochem Biophys Res Commun. 2021 Nov 05. pii: S0006-291X(21)01495-9. [Epub ahead of print]584 53-59

Development of simultaneous quantitative analysis of tricarboxylic acid cycle metabolites to identify specific metabolites in cancer cells by targeted metabolomic approach.

Tetsushi Yamamoto, Kanta Sato, Masafumi Yamaguchi, Kuniko Mitamura, Atsushi Taga.

  The tricarboxylic acid (TCA) cycle is one of the most important pathways of energy metabolism, and the profiles of its components are influenced by factors such as diseases and diets. Therefore, the differences in metabolic profile of TCA cycle between healthy and cancer cells have been the focus of studies to understand pathological conditions. In this study, we developed a quantitative method to measure TCA cycle metabolites using LC-MS/MS to obtain useful metabolic profiles for development of diagnostic and therapeutic methods for cancer. We successfully analyzed 11 TCA cycle metabolites by LC MS/MS with high reproducibility by using a PFP column with 0.5% formic acid as a mobile phase. Next, we analyzed the concentration of TCA cycle metabolites in human cell lines (HaCaT: normal skin keratinocytes; A431: skin squamous carcinoma cells; SW480: colorectal cancer cells). We observed reduced concentration of succinate and increased concentration of citrate, 2-hydroxyglutarate, and glutamine in A431 cells as compared with HaCaT cells. On the other hand, decreased concentration of isocitrate, fumarate, and α-ketoglutarate and increased concentration of malate, glutamine, and glutamate in A431 cells were observed in comparison with SW480 cells. These findings suggested the possibility of identifying disease-specific metabolites and/or organ-specific metabolites by using this targeted metabolomic analysis.

Keywords:  Cancer; Energy metabolism; LC-MS; TCA cycle; Targeted metabolomics

DOI:  https://doi.org/10.1016/j.bbrc.2021.10.072
Cancers (Basel). 2021 Nov 08. pii: 5580. [Epub ahead of print]13(21):

A Prostate Cancer Proteomics Database for SWATH-MS Based Protein Quantification.

Ammara Muazzam, Davide Chiasserini, Janet Kelsall, Nophar Geifman, Anthony D Whetton, Paul A Townsend.

  Prostate cancer is the most frequent form of cancer in men, accounting for more than one-third of all cases. Current screening techniques, such as PSA testing used in conjunction with routine procedures, lead to unnecessary biopsies and the discovery of low-risk tumours, resulting in overdiagnosis. SWATH-MS is a well-established data-independent (DI) method requiring prior knowledge of targeted peptides to obtain valuable information from SWATH maps. In response to the growing need to identify and characterise protein biomarkers for prostate cancer, this study explored a spectrum source for targeted proteome analysis of blood samples. We created a comprehensive prostate cancer serum spectral library by combining data-dependent acquisition (DDA) MS raw files from 504 patients with low, intermediate, or high-grade prostate cancer and healthy controls, as well as 304 prostate cancer-related protein in silico assays. The spectral library contains 114,684 transitions, which equates to 18,479 peptides translated into 1227 proteins. The robustness and accuracy of the spectral library were assessed to boost confidence in the identification and quantification of prostate cancer-related proteins across an independent cohort, resulting in the identification of 404 proteins. This unique database can facilitate researchers to investigate prostate cancer protein biomarkers in blood samples. In the real-world use of the spectrum library for biomarker detection, using a signature of 17 proteins, a clear distinction between the validation cohort's pre- and post-treatment groups was observed. Data are available via ProteomeXchange with identifier PXD028651.

Keywords:  SWATH-MS; blood proteomics; mass spectrometry; peptide; prostate cancer; protein; spectral library

DOI:  https://doi.org/10.3390/cancers13215580
Nat Commun. 2021 Nov 12. 12(1): 6572

Apoptotic stress-induced FGF signalling promotes non-cell autonomous resistance to cell death.

Florian J Bock, Egor Sedov, Elle Koren, Anna L Koessinger, Catherine Cloix, Désirée Zerbst, Dimitris Athineos, Jayanthi Anand, Kirsteen J Campbell, Karen Blyth, Yaron Fuchs, Stephen W G Tait.

Damaged or superfluous cells are typically eliminated by apoptosis. Although apoptosis is a cell-autonomous process, apoptotic cells communicate with their environment in different ways. Here we describe a mechanism whereby cells under apoptotic stress can promote survival of neighbouring cells. We find that upon apoptotic stress, cells release the growth factor FGF2, leading to MEK-ERK-dependent transcriptional upregulation of pro-survival BCL-2 proteins in a non-cell autonomous manner. This transient upregulation of pro-survival BCL-2 proteins protects neighbouring cells from apoptosis. Accordingly, we find in certain cancer types a correlation between FGF-signalling, BCL-2 expression and worse prognosis. In vivo, upregulation of MCL-1 occurs in an FGF-dependent manner during skin repair, which regulates healing dynamics. Importantly, either co-treatment with FGF-receptor inhibitors or removal of apoptotic stress restores apoptotic sensitivity to cytotoxic therapy and delays wound healing. These data reveal a pathway by which cells under apoptotic stress can increase resistance to cell death in surrounding cells. Beyond mediating cytotoxic drug resistance, this process also provides a potential link between tissue damage and repair.

DOI: https://doi.org/10.1038/s41467-021-26613-0
Curr Opin Lipidol. 2021 Dec 01. 32(6): 387-388

Fatty acid metabolism in cancer cells - the power of plasticity.

Sonja C Stadler, Ralph Burkhardt.

DOI: https://doi.org/10.1097/MOL.0000000000000788
STAR Protoc. 2021 Dec 17. 2(4): 100918

Protocol for the assessment of mTOR activity in mouse primary hepatocytes.

Ana Belén Plata-Gómez, María Crespo, Celia de la Calle Arregui, Lucía de Prado-Rivas, Guadalupe Sabio, Alejo Efeyan.

  We present a protocol for measuring the activity of the mechanistic target of rapamycin (mTOR) pathway in ex vivo isolated mouse primary hepatocytes. It can be used as a tool for genetic, pharmacological, metabolomic, and signal transduction procedures. We discuss critical aspects for improving yield, viability, and modulation of the mTOR pathway. This protocol can be adapted to other signaling cascades and is compatible with multiple readouts. For complete details on the use and execution of this protocol, please refer to Ortega-Molina et al. (2021).

Keywords:  Cell culture; Cell isolation; Cell-based Assays; Metabolism; Metabolomics; Signal Transduction

DOI:  https://doi.org/10.1016/j.xpro.2021.100918
Anal Chem. 2021 Nov 10.

Metabolite Identification Using Infrared Ion Spectroscopy─Novel Biomarkers for Pyridoxine-Dependent Epilepsy.

Rianne E van Outersterp, Udo F H Engelke, Jona Merx, Giel Berden, Mathias Paul, Thomas Thomulka, Albrecht Berkessel, Marleen C D G Huigen, Leo A J Kluijtmans, Jasmin Mecinović, Floris P J T Rutjes, Clara D M van Karnebeek, Ron A Wevers, Thomas J Boltje, Karlien L M Coene, Jonathan Martens, Jos Oomens.

Untargeted liquid chromatography-mass spectrometry (LC-MS)-based metabolomics strategies are being increasingly applied in metabolite screening for a wide variety of medical conditions. The long-standing "grand challenge" in the utilization of this approach is metabolite identification─confidently determining the chemical structures of m/z-detected unknowns. Here, we use a novel workflow based on the detection of molecular features of interest by high-throughput untargeted LC-MS analysis of patient body fluids combined with targeted molecular identification of those features using infrared ion spectroscopy (IRIS), effectively providing diagnostic IR fingerprints for mass-isolated targets. A significant advantage of this approach is that in silico-predicted IR spectra of candidate chemical structures can be used to suggest the molecular structure of unknown features, thus mitigating the need for the synthesis of a broad range of physical reference standards. Pyridoxine-dependent epilepsy (PDE-ALDH7A1) is an inborn error of lysine metabolism, resulting from a mutation in the ALDH7A1 gene that leads to an accumulation of toxic levels of α-aminoadipic semialdehyde (α-AASA), piperideine-6-carboxylate (P6C), and pipecolic acid in body fluids. While α-AASA and P6C are known biomarkers for PDE in urine, their instability makes them poor candidates for diagnostic analysis from blood, which would be required for application in newborn screening protocols. Here, we use combined untargeted metabolomics-IRIS to identify several new biomarkers for PDE-ALDH7A1 that can be used for diagnostic analysis in urine, plasma, and cerebrospinal fluids and that are compatible with analysis in dried blood spots for newborn screening. The identification of these novel metabolites has directly provided novel insights into the pathophysiology of PDE-ALDH7A1.

DOI: https://doi.org/10.1021/acs.analchem.1c02896
Int J Mol Sci. 2021 Oct 21. pii: 11358. [Epub ahead of print]22(21):

A Lipidomics Atlas of Selected Sphingolipids in Multiple Mouse Nervous System Regions.

Chunyan Wang, Juan Pablo Palavicini, Xianlin Han.

  Many lipids, including sphingolipids, are essential components of the nervous system. Sphingolipids play critical roles in maintaining the membrane structure and integrity and in cell signaling. We used a multi-dimensional mass spectrometry-based shotgun lipidomics platform to selectively analyze the lipid species profiles of ceramide, sphingomyelin, cerebroside, and sulfatide; these four classes of sphingolipids are found in the central nervous system (CNS) (the cerebrum, brain stem, and spinal cord) and peripheral nervous system (PNS) (the sciatic nerve) tissues of young adult wild-type mice. Our results revealed that the lipid species profiles of the four sphingolipid classes in the different nervous tissues were highly distinct. In addition, the mRNA expression of sphingolipid metabolism genes-including the ceramidase synthases that specifically acylate the N-acyl chain of ceramide species and sphingomyelinases that cleave sphingomyelins generating ceramides-were analyzed in the mouse cerebrum and spinal cord tissue in order to better understand the sphingolipid profile differences observed between these nervous tissues. We found that the distinct profiles of the determined sphingolipids were consistent with the high selectivity of ceramide synthases and provided a potential mechanism to explain region-specific CNS ceramide and sphingomyelin levels. In conclusion, we portray for the first time a lipidomics atlas of select sphingolipids in multiple nervous system regions and believe that this type of knowledge could be very useful for better understanding the role of this lipid category in the nervous system.

Keywords:  ceramide synthases; lipid profiling; lipidomics; nervous system; sphingolipid

DOI:  https://doi.org/10.3390/ijms222111358
Elife. 2021 Nov 08. pii: e70843. [Epub ahead of print]10

Rapid and sensitive detection of SARS-CoV-2 infection using quantitative peptide enrichment LC-MS analysis.

Andreas Hober, Khue Hua Tran-Minh, Dominic Foley, Thomas McDonald, Johannes Pc Vissers, Rebecca Pattison, Samantha Ferries, Sigurd Hermansson, Ingvar Betner, Mathias Uhlén, Morteza Razavi, Richard Yip, Matthew E Pope, Terry W Pearson, Leigh N Andersson, Amy Bartlett, Lisa Calton, Jessica J Alm, Lars Engstrand, Fredrik Edfors.

  Reliable, robust, large-scale molecular testing for SARS-CoV-2 is essential for monitoring the ongoing Covid-19 pandemic. We have developed a scalable analytical approach to detect viral proteins based on peptide immunoaffinity enrichment combined with liquid chromatography - mass spectrometry (LC-MS). This is a multiplexed strategy, based on targeted proteomics analysis and read-out by LC-MS, capable of precisely quantifying and confirming the presence of SARS-CoV-2 in PBS swab media from combined throat/nasopharynx/saliva samples.<br />The results reveal that the levels of SARS-CoV-2 measured by LC-MS correlate well with their corresponding RT-PCR readout (r=0.79). The analytical workflow shows similar turnaround times as regular RT-PCR instrumentation with a quantitative readout of viral proteins corresponding to cycle thresholds (Ct) equivalents ranging from 21 to 34. Using RT-PCR as a reference, we demonstrate that the LC-MS-based method has 100% negative percent agreement (estimated specificity) and 95% positive percent agreement (estimated sensitivity) when analyzing clinical samples collected from asymptomatic individuals with a Ct within the limit of detection of the mass spectrometer (Ct ≤30). These results suggest that a scalable analytical method based on LC-MS has a place in future pandemic preparedness centers to complement current virus detection technologies.

Keywords:  human; immunology; infectious disease; inflammation; microbiology

DOI:  https://doi.org/10.7554/eLife.70843