Publications by authors named "Pierre Chaurand"

76 Publications

rMSIcleanup: an open-source tool for matrix-related peak annotation in mass spectrometry imaging and its application to silver-assisted laser desorption/ionization.

J Cheminform 2020 Jul 22;12(1):45. Epub 2020 Jul 22.

Department of Electronic Engineering, Rovira i Virgili University, Tarragona, Spain.

Mass spectrometry imaging (MSI) has become a mature, widespread analytical technique to perform non-targeted spatial metabolomics. However, the compounds used to promote desorption and ionization of the analyte during acquisition cause spectral interferences in the low mass range that hinder downstream data processing in metabolomics applications. Thus, it is advisable to annotate and remove matrix-related peaks to reduce the number of redundant and non-biologically-relevant variables in the dataset. We have developed rMSIcleanup, an open-source R package to annotate and remove signals from the matrix, according to the matrix chemical composition and the spatial distribution of its ions. To validate the annotation method, rMSIcleanup was challenged with several images acquired using silver-assisted laser desorption ionization MSI (AgLDI MSI). The algorithm was able to correctly classify m/z signals related to silver clusters. Visual exploration of the data using Principal Component Analysis (PCA) demonstrated that annotation and removal of matrix-related signals improved spectral data post-processing. The results highlight the need for including matrix-related peak annotation tools such as rMSIcleanup in MSI workflows.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s13321-020-00449-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7374922PMC
July 2020

Visualizing the distribution of strawberry plant metabolites at different maturity stages by MALDI-TOF imaging mass spectrometry.

Food Chem 2021 May 10;345:128838. Epub 2020 Dec 10.

Department of Bioresource Engineering, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue H9X 3V9, Canada.

This study aimed to visualize differences in the distribution of citric acid, soluble sugars, and anthocyanins in strawberries at four different maturity stages (green to red strawberries) by matrix-assisted laser desorption/ionization time-of-flight imaging mass spectrometry (MALDI-TOF IMS). Results demonstrated citric acid and sugars are evenly distributed in the entire fruit at all maturity stages, while most of anthocyanins are mainly located in the periphery of fruit with increased abundance in red strawberries, indicating a correlation with the colour attributes. Sugar in red strawberries (11.92 brix) increased by two-fold compared to the green ones (6.23 brix). Finally, absolute quantitation of each compound from HPLC analyses support the quantitative results from MALDI-TOF IMS. The results provide a deeper understanding in the changes and distribution of phytochemicals during the growth of strawberries, and demonstrates the usefulness of IMS for plant breeding and postharvest technology.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.foodchem.2020.128838DOI Listing
May 2021

A matrix-assisted laser desorption/ionization imaging mass spectrometric approach to study weight-related changes within thyroid tissue.

J Mass Spectrom 2021 Jan 10;56(1):e4671. Epub 2020 Nov 10.

Obesity Research Center, College of Medicine, King Saud University, P.O. Box 2925 (98), Riyadh, 11461, Saudi Arabia.

Obesity is associated with numerous comorbidities along with abnormalities of the endocrine system, more commonly manifesting as dysfunctions of the thyroid gland such as goiter. Changes in weight, especially an increase, could lead to an increase in the incidence of thyroid dysfunction; however, its pathophysiology remains to be elucidated. In the present study, we aimed to interrogate the changes in the protein distribution and abundance between the lean patients and patients with obesity thyroid tissue sections through utilizing this technique. The FFPE-fixed thyroid tissue blocks from the selected cases and controls were identified and targeted for matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) analysis. Patients in the 30 to 75 years age group and undergoing total thyroidectomy for benign thyroid disease were recruited. Patients with thyroid cancers, autoimmune disorders, and other inflammatory conditions were excluded from the study. The selected patients were divided into two groups according to their BMIs: lean (BMI < 25) and obese (BMI > 35). An initial trial set was used as a pilot study for the optimization of the MALDI IMS protocol that was next applied to the selected thyroid tissues. MALDI IMS data from all the samples were aligned and statistical analysis carried out by k-means and linear discriminant analysis (LDA) classification model using principle component analysis (PCA) results were evaluated between the two groups: controls (lean) and cases (obese). Receiver operator characteristic (ROC) curves were alternatively used to calculate the variability of the identified peptides. The discriminating peptides were also independently identified and related to their corresponding proteins by using liquid chromatography and tandem mass spectrometry (LC-MS/MS) analyses. Eight peptides mainly from thyroglobulin were found to be upregulated whereas 10 others were found to be downregulated in the lean compared to the obese group. Through this technique, we will be able to better understand the relationship between the disease entity and obesity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jms.4671DOI Listing
January 2021

Multimodal Imaging Mass Spectrometry to Identify Markers of Pulmonary Arterial Hypertension in Human Lung Tissue Using MALDI-ToF, ToF-SIMS, and Hybrid SIMS.

Anal Chem 2020 09 17;92(17):12079-12087. Epub 2020 Aug 17.

Université Paris-Saclay, CNRS, Institut de Chimie des Substances Naturelles, UPR 2301, 91198, Gif-sur-Yvette, France.

Pulmonary arterial hypertension (PAH) is a rare and deadly disease affecting roughly 15-60 people per million in Europe with a poorly understood pathology. There are currently no diagnostic tools for early detection nor does a curative treatment exist. The lipid composition of arteries in lung tissue samples from human PAH and control patients were investigated using matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) combined with time-of-flight secondary ion mass spectrometry (TOF-SIMS) imaging. Using random forests as an IMS data analysis technique, it was possible to identify the ion at / 885.6 as a marker of PAH in human lung tissue. The / 885.6 ion intensity was shown to be significantly higher around diseased arteries and was confirmed to be a diacylglycerophosphoinositol PI(C18:0/C20:4) via MS/MS using a novel hybrid SIMS instrument. The discovery of a potential biomarker opens up new research avenues which may finally lead to a better understanding of the PAH pathology and highlights the vital role IMS can play in modern biomedical research.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.analchem.0c02815DOI Listing
September 2020

Minimizing Visceral Fat Delocalization on Tissue Sections with Porous Aluminum Oxide Slides for Imaging Mass Spectrometry.

Anal Chem 2020 04 17;92(7):5158-5167. Epub 2020 Mar 17.

Department of Chemistry, Université de Montréal, Montreal, Quebec, Canada H2V 0B3.

A high correlation of bioanalytes with their corresponding histologies is the landmark feature of matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS). Lipids are one of the most studied classes of biomolecules, and monitoring lipid distribution and abundance in tissue samples can lead to major inputs in the understanding of disease. Lipid delocalization and ion suppression are two major effects that can lead to misinterpretation of the IMS results to an unaware analyst. We and others have observed that tissue specimens containing high amounts of visceral fat are challenging to analyze because of fat delocalization on and off section leading to significant triacylglyceride and phospholipid delocalization and major ion suppression effects. In this work, we introduce a novel and easy to produce reusable porous aluminum oxide sample slide that minimizes visceral fat delocalization after thaw-mounting of tissue sections. Using fatty mouse kidneys and other tissues, we demonstrate its efficacy in minimizing delocalization of triacylglycerides, the primary constituents of fat, and the resulting beneficial effects on phospholipid MALDI IMS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.analchem.9b05665DOI Listing
April 2020

Silver spray deposition for AgLDI imaging MS of cholesterol and other olefins on thin tissue sections.

J Mass Spectrom 2020 Apr 30;55(4):e4428. Epub 2019 Aug 30.

Department of Chemistry, University of Montreal, Montreal, Quebec, Canada, H3C 3J7.

Olefins such as cholesterol and unsaturated fatty acids play important biological roles. Silver-assisted laser desorption ionization (AgLDI) takes advantage of the strong affinity of silver to conjugate with double bonds to selectively ionize these molecules for imaging mass spectrometry (IMS) experiments. For IMS studies, two main approaches for silver deposition have been described in the literature: fine coating by silver sputtering and spray deposition of silver nanoparticles. While these approaches allow for extremely high resolution IMS experiments to be conducted, they are not readily available to all laboratories. Herein, we present a silver nitrate spray deposition approach as an alternative to silver sputtering and nanoparticle deposition for routine IMS analysis. The silver nitrate spray has the same level of specificity and sensitivity for olefins, particularly cholesterol, and has shown to be capable of IMS experiments down to 10-μm spatial resolution. Minimal sample preparation and the affordability of silver nitrate make this a convenient and accessible technique worth considering.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jms.4428DOI Listing
April 2020

Probiotics Modulate a Novel Amphibian Skin Defense Peptide That Is Antifungal and Facilitates Growth of Antifungal Bacteria.

Microb Ecol 2020 Jan 16;79(1):192-202. Epub 2019 May 16.

Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.

Probiotics can ameliorate diseases of humans and wildlife, but the mechanisms remain unclear. Host responses to interventions that change their microbiota are largely uncharacterized. We applied a consortium of four natural antifungal bacteria to the skin of endangered Sierra Nevada yellow-legged frogs, Rana sierrae, before experimental exposure to the pathogenic fungus Batrachochytrium dendrobatidis (Bd). The probiotic microbes did not persist, nor did they protect hosts, and skin peptide sampling indicated immune modulation. We characterized a novel skin defense peptide brevinin-1Ma (FLPILAGLAANLVPKLICSITKKC) that was downregulated by the probiotic treatment. Brevinin-1Ma was tested against a range of amphibian skin cultures and found to inhibit growth of fungal pathogens Bd and B. salamandrivorans, but enhanced the growth of probiotic bacteria including Janthinobacterium lividum, Chryseobacterium ureilyticum, Serratia grimesii, and Pseudomonas sp. While commonly thought of as antimicrobial peptides, here brevinin-1Ma showed promicrobial function, facilitating microbial growth. Thus, skin exposure to probiotic bacterial cultures induced a shift in skin defense peptide profiles that appeared to act as an immune response functioning to regulate the microbiome. In addition to direct microbial antagonism, probiotic-host interactions may be a critical mechanism affecting disease resistance.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00248-019-01385-9DOI Listing
January 2020

Mapping the fly Malpighian tubule lipidome by imaging mass spectrometry.

J Mass Spectrom 2019 Jun;54(6):557-566

Department of Chemistry, University of Montreal, Pavillon Roger-Gaudry, 2900, boul. Édouard-Montpetit, Montreal, QC, Canada, H3C 3J7.

Matrix-assisted laser/desorption ionization imaging mass spectrometry (MALDI IMS) is an analytical technique for understanding the spatial distribution of biomolecules across a sample surface. Originally employed for mammalian tissues, this technology has been adapted to study specimens as diverse as microbes and cell cultures, food such as strawberries, and invertebrates including the vinegar fly Drosophila melanogaster. As an ideal model organism, Drosophila has brought greater understanding about conserved biological processes, organism development, and diseased states and even informed management practices of agriculturally and environmentally important species. Drosophila displays anatomically separated renal (Malpighian) tubules that are the physiological equivalent to the vertebrate nephron. Insect Malpighian tubules are also responsible for pesticide detoxification. In this article, we first describe an effective workflow and sample preparation method to study the phospholipid distribution of the Malpighian tubules that initially involves the manual microdissection of the tubules in saline buffer followed by a series of washes to remove excess salt and enhances the phospholipid signals prior to matrix deposition and IMS at 25-μm spatial resolution. We also established a complementary methodology for lipid IMS analysis of whole-body fly sections using a dual-polarity data acquisition approach at the same spatial resolution after matrix deposition by sublimation. Both procedures yield rich signal profiles from the major phospholipid classes. The reproducibility and high-quality results offered by these methodologies enable cohort studies of Drosophila through MALDI IMS.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jms.4366DOI Listing
June 2019

Mapping the triglyceride distribution in NAFLD human liver by MALDI imaging mass spectrometry reveals molecular differences in micro and macro steatosis.

Anal Bioanal Chem 2019 Feb 5;411(4):885-894. Epub 2018 Dec 5.

Department of Surgery, McGill University Health Center, 1650 Cedar Avenue, Montreal, Quebec, H3G 1A4, Canada.

Hepatic lipid accumulation, mainly in the form of triglycerides (TGs), is the hallmark of non-alcoholic fatty liver disease (NAFLD). To date, the spatial distribution of individual lipids in NAFLD-affected livers is not well characterized. This study aims to map the triglyceride distribution in normal human liver samples and livers with NAFLD and cirrhosis with imaging mass spectrometry (MALDI IMS). Specifically, whether individual triglyceride species differing by fatty acid chain length and degree of saturation correlate with the histopathological features of NAFLD as identified with classical H&E. Using a recently reported sodium-doped gold-assisted laser desorption/ionization IMS sample preparation, 20 human liver samples (five normal livers, five samples with simple steatosis, five samples with steatohepatitis, and five samples with cirrhosis) were analyzed at 10-μm lateral resolution. A total of 24 individual lipid species, primarily neutral lipids, were identified (22 TGs and two phospholipids). In samples with a low level of steatosis, TGs accumulated around the pericentral zone. In all samples, TGs with different degrees of side-chain saturation and side-chain length demonstrated differential distribution. Furthermore, hepatocytes containing macro lipid droplets were highly enriched in fully saturated triglycerides. This enrichment was also observed in areas of hepatocyte ballooning in samples with steatohepatitis and cirrhosis. In conclusion, macro lipid droplets in NAFLD are enriched in fully saturated triglycerides, indicating a possible increase in de novo lipogenesis that leads to steatohepatitis and cirrhosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-018-1506-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6513670PMC
February 2019

Mild Methylenetetrahydrofolate Reductase Deficiency Alters Inflammatory and Lipid Pathways in Liver.

Mol Nutr Food Res 2019 02 23;63(3):e1801001. Epub 2018 Nov 23.

Departments of Human Genetics and Pediatrics, McGill University, McGill University Health Center (MUHC), Montreal, H4A 3J1, Canada.

Scope: Dietary and genetic folate disturbances can lead to nonalcoholic fatty liver disease (NAFLD). A common variant in methylenetetrahydrofolate reductase (MTHFR 677C→T) causes mild MTHFR deficiency with lower 5-methyltetrahydrofolate for methylation reactions. The goal is to determine whether mild murine MTHFR deficiency contributes to NAFLD-related effects.

Methods And Results: Wild-type and Mthfr mice, a model for the human variant, are fed control (CD) or high-fat (HFAT) diets for 8 weeks. On both diets, MTHFR deficiency results in decreased S-adenosylmethionine, increased S-adenosylhomocysteine, and decreased betaine with reduced methylation capacity, and changes in expression of several inflammatory or anti-inflammatory mediators (Saa1, Apoa1, and Pon1). On CD, MTHFR deficiency leads to microvesicular steatosis with expression changes in lipid regulators Xbp1s and Cyp7a1. The combination of MTHFR deficiency and HFAT exacerbates changes in inflammatory mediators and introduces additional effects on inflammation (Saa2) and lipid metabolism (Nr1h4, Srebf1c, Ppara, and Crot). These effects are consistent with increased expression of pro-inflammatory HDL precursors and greater lipid accumulation. MTHFR deficiency may enhance liver injury through alterations in methylation capacity, inflammatory response, and lipid metabolism.

Conclusion: Individuals with the MTHFR variant may be at increased risk for liver disease and related complications, particularly when consuming high-fat diets.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/mnfr.201801001DOI Listing
February 2019

Co-registration and analysis of multiple imaging mass spectrometry datasets targeting different analytes.

Bioinformatics 2019 04;35(7):1261-1262

Department of Chemistry, Université de Montréal, Montreal, Quebec, Canada.

Motivation: MALDI imaging mass spectrometry (IMS) has been successfully used to image a variety of biomolecules. Imaging of the many classes of biomolecules is often achieved through several incompatible sample preparations. Thus, multiple datasets must be acquired from multiple tissue sections to obtain a total molecular overview of a single sample. Addressing the need for single datasets from multiple IMS analyses, we developed the R package RegCombIMS as an extension of R package Cardinal to co-register, combine and create single IMS datasets acquired from serial sections of tissue.

Results: Dataset recombination and analysis is achieved by registration of the IMS datasets to a single coordinate space. The workflow allows for correlation of ions from IMS acquisitions that require incompatible sample preparations as well as multivariate analysis to mine the combined dataset for rapid and more thorough molecular query.

Availability And Implementation: The source code and example data are freely available at https://github.com/NHPatterson/RegCombIMS. All code was implemented in R.

Supplementary Information: Supplementary data are available at Bioinformatics online.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/bioinformatics/bty780DOI Listing
April 2019

Detection of exogenous substances in latent fingermarks by silver-assisted LDI imaging MS: perspectives in forensic sciences.

Analyst 2018 Jul;143(15):3586-3594

University of Montreal, Department of Chemistry, Canada.

For over one hundred years, the fingerprint has reigned as one of the most trusted pieces of forensic evidence for suspect identification. In the last few decades, the modernization of chemical analysis technologies led scientists to explore new possibilities to further analyse fingermarks sampled from a crime scene. Indeed, the detection of chemicals a suspect has been in contact with before or during the crime can provide valuable insights into criminal investigations. In this regard, imaging mass spectrometry (IMS) has shown to be a powerful tool for the analysis of fingermarks by combining suspect identification and the detection of numerous endogenous and exogenous compounds. A novel approach developed in our laboratory, silver-assisted laser desorption ionization (AgLDI), was adopted to allow for the chemical analysis of latent fingermarks left on nonconductive surfaces (such as paper, cardboard, plastic and forensic lifting tape) with a time-of-flight mass spectrometer. In this study, we continue to evaluate the potential of AgLDI IMS to provide circumstantial evidence by detecting exogenous substances. We first demonstrate that owner-specific chemical signatures can be recovered from fingermarks based on the presence of several cosmetics and personal care products. We then show the possibility of detecting and imaging fingermarks containing three common illicit drugs, namely tetrahydrocannabinol, cocaine and heroin. Finally, we demonstrate that the methodology also allows us to successfully image bloody fingermarks after appropriate forensic enhancement treatments. Overall, we believe that AgLDI IMS has significant potential that could positively contribute to forensic investigations.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c8an00688aDOI Listing
July 2018

Insights into the MALDI Process after Matrix Deposition by Sublimation Using 3D ToF-SIMS Imaging.

Anal Chem 2018 02 17;90(3):1907-1914. Epub 2018 Jan 17.

Institut de Chimie des Substances Naturelles, CNRS UPR 2301, Université Paris-Sud, Université Paris-Saclay , 91190 Gif-sur-Yvette, France.

Imaging mass spectrometry (IMS) has become a powerful tool to characterize the spatial distribution of biomolecules in thin tissue sections. In the case of matrix-assisted laser desorption ionization (MALDI) IMS, homogeneous matrix deposition is critical to produce high-quality ion images, and sublimation in particular has shown to be an excellent matrix deposition method for the imaging of lipids. Matrix deposition by sublimation is, however, a completely solvent-free system, which ought to prevent the mixing of matrix and analytes thought to be necessary for successful MALDI. Using 3D time-of-flight secondary ion imaging mass spectrometry, we have studied the matrix-tissue interface in 3D with high resolution to understand the MALDI process of lipids after matrix deposition by sublimation. There is a strong indication that diffusion is the process by which lipids migrate from the tissue to the matrix layer. We show that triacylglycerols and phospholipids have a delayed migratory trend as compared to diacylglycerols and monoacylglycerols, which is dependent on time and matrix thickness. Additional experiments show that a pure lipid's capacity to migrate into the matrix is dependent on its fluidity at room temperature. Furthermore, it is shown that cholesterol can only migrate in the presence of a (fluid) lipid and appears to fluidize lipids, which could explain its colocalization with the diacylglycerols and monoacylglycerols in the matrix.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.analchem.7b03993DOI Listing
February 2018

A Proteomics Based Approach Reveals Differential Regulation of Visceral Adipose Tissue Proteins between Metabolically Healthy and Unhealthy Obese Patients.

Mol Cells 2017 Sep 20;40(9):685-695. Epub 2017 Sep 20.

Obesity Research Center, College of Medicine, King Saud University, Saudi Arabia.

Obesity and the metabolic disorders that constitute metabolic syndrome are a primary cause of morbidity and mortality in the world. Nonetheless, the changes in the proteins and the underlying molecular pathways involved in the relevant pathogenesis are poorly understood. In this study a proteomic analysis of the visceral adipose tissue isolated from metabolically healthy and unhealthy obese patients was used to identify presence of altered pathway(s) leading to metabolic dysfunction. Samples were obtained from 18 obese patients undergoing bariatric surgery and were subdivided into two groups based on the presence or absence of comorbidities as defined by the International Diabetes Federation. Two dimensional difference in-gel electrophoresis coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry was carried out. A total of 28 proteins were identified with a statistically significant difference in abundance and a 1.5-fold change (ANOVA, p ≤ 0.05) between the groups. 11 proteins showed increased abundance while 17 proteins were decreased in the metabolically unhealthy obese compared to the healthy obese. The differentially expressed proteins belonged broadly to three functional categories: (i) protein and lipid metabolism (ii) cytoskeleton and (iii) regulation of other metabolic processes. Network analysis by Ingenuity pathway analysis identified the NFκB, IRK/MAPK and PKC as the nodes with the highest connections within the connectivity map. The top network pathway identified in our protein data set related to cellular movement, hematological system development and function, and immune cell trafficking. The VAT proteome between the two groups differed substantially between the groups which could potentially be the reason for metabolic dysfunction.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.14348/molcells.2017.0073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5638776PMC
September 2017

Life history linked to immune investment in developing amphibians.

Conserv Physiol 2016 26;4(1):cow025. Epub 2016 Aug 26.

Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA; Department of Biological Science, Vanderbilt University, Nashville, TN 37235-1634, USA; Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232-2363, USA.

The broad diversity of amphibian developmental strategies has been shaped, in part, by pathogen pressure, yet trade-offs between the rate of larval development and immune investment remain poorly understood. The expression of antimicrobial peptides (AMPs) in skin secretions is a crucial defense against emerging amphibian pathogens and can also indirectly affect host defense by influencing the composition of skin microbiota. We examined the constitutive or induced expression of AMPs in 17 species at multiple life-history stages. We found that AMP defenses in tadpoles of species with short larval periods (fast pace of life) were reduced in comparison with species that overwinter as tadpoles and grow to a large size. A complete set of defensive peptides emerged soon after metamorphosis. These findings support the hypothesis that species with a slow pace of life invest energy in AMP production to resist potential pathogens encountered during the long larval period, whereas species with a fast pace of life trade this investment in defense for more rapid growth and development.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/conphys/cow025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5001151PMC
August 2016

Multimodal detection of GM2 and GM3 lipid species in the brain of mucopolysaccharidosis type II mouse by serial imaging mass spectrometry and immunohistochemistry.

Anal Bioanal Chem 2017 Feb 21;409(5):1425-1433. Epub 2016 Nov 21.

Department of Chemistry, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC, H3C 3J7, Canada.

Mucopolysaccharidosis type II (Hunter's disease) mouse model (IdS-KO) was investigated by both imaging mass spectrometry (IMS) and immunohistochemistry (IHC) performed on the same tissue sections. For this purpose, IdS-KO mice brain sections were coated with sublimated 1,5-diaminonaphtalene and analyzed by high spatial resolution IMS (5 μm) and anti-GM3 IHC on the same tissue sections to characterize the ganglioside monosialated ganglioside (GM) deposits found in Hunter's disease. IMS analysis have found that two species of GM3 and GM2 that are only different due to the length of their fatty acid residue (stearic or arachidic residue) were overexpressed in the IdS-KO mice compared to a control mouse. GM3 and GM2 were characterized by on-tissue exact mass and MS/MS compared to a GM3 standard. Realignment of both IMS and IHC data sets further confirmed the observed regioselective signal previously detected by providing direct correlation of the IMS image for the two GM3 overly expressed MS signals with the anti-GM3 IHC image. Furthermore, these regioselective GM MS signals were also found to have highly heterogeneous distributions within the GM3-IHC staining. Some deposits showed high content in GM3 and GM2 stearic species (r = 0.74) and others had more abundant GM3 and GM2 arachidic species (r = 0.76). Same-section analysis of Hunter's disease mouse model by both high spatial resolution IMS and IHC provides a more in-depth analysis of the composition of the GM aggregates while providing spatial distribution of the observed molecular species. Graphical Abstract Ganglioside imaging mass spectrometry followed by immunohistochemistry performed on the same tissue section.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-016-0076-xDOI Listing
February 2017

Assessment of pathological response to therapy using lipid mass spectrometry imaging.

Sci Rep 2016 11 14;6:36814. Epub 2016 Nov 14.

Department of Surgery, McGill University Health Center, Quebec, Canada.

In many cancers, the establishment of a patient's future treatment regime often relies on histopathological assessment of tumor tissue specimens in order to determine the extent of the 'pathological response' to a given therapy. However, histopathological assessment of pathological response remains subjective. Here we use MALDI mass spectrometry imaging to generate lipid signatures from colorectal cancer liver metastasis specimens resected from patients preoperatively treated with chemotherapy. Using these signatures we obtained a unique pathological response score that correlates with prognosis. In addition, we identify single lipid moieties that are overexpressed in different histopathological features of the tumor, which have potential as new biomarkers for assessing response to therapy. These data show that computational methods, focusing on the lipidome, can be used to determine prognostic markers for response to chemotherapy and may potentially improve risk assessment and patient care.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/srep36814DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5107952PMC
November 2016

Sodium-Doped Gold-Assisted Laser Desorption Ionization for Enhanced Imaging Mass Spectrometry of Triacylglycerols from Thin Tissue Sections.

Anal Chem 2016 06 11;88(11):6018-25. Epub 2016 May 11.

Department of Chemistry, University of Montreal , Montreal, Quebec H3C 3J7, Canada.

The deposition of sodium salts followed by a sputtered layer of gold has been demonstrated to be a power combination for the analysis of triacylglycerols (TAGs) from tissue sections by laser desorption ionization (LDI) imaging mass spectrometry (IMS). Various sodium salts were tested for their capability to ionize TAGs and their ability to produce fast drying, small crystals (≤3 μm). The spray deposition of a sodium acetate and carbonate buffer mixture at pH 10.3 on which a 28 ± 3 nm sputtered layer of gold (Au-CBS) is subsequently deposited was found to provide the most effective combination for TAG analysis by high imaging resolution IMS. Under these conditions, a 30-fold increase in TAG signal intensity was observed when compared to matrix-assisted LDI (MALDI) methods using 2,5-dihydrobenzoic acid as matrix. Furthermore, Au-CBS led to an increase in the number of detected TAG species from ∼7 with DHB to more than 25 with the novel method, while few phospholipid signals were observed. These results were derived from the IMS investigation of fresh frozen mouse liver and rabbit adrenal gland tissue sections with a range of higher spatial resolutions between 35 and 10 μm. Au-CBS-LDI MS presents a highly sensitive and specific alternative to MALDI MS for imaging of TAGs from tissue sections. This novel approach has the potential to provide new biological insights on the role of TAGs in both health and disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.analchem.6b01141DOI Listing
June 2016

Three-dimensional imaging MS of lipids in atherosclerotic plaques: Open-source methods for reconstruction and analysis.

Proteomics 2016 06 9;16(11-12):1642-51. Epub 2016 May 9.

Department of Chemistry, University of Montreal, Montreal, Quebec, Canada.

Three-dimensional MALDI imaging MS (IMS) is a growing branch of IMS still requiring developments in methodology and technology to make the technique routinely accessible. Many challenges are simply a matter of producing 3D reconstructions and interpreting them in a timely fashion. In this aim and using analysis of lipids from atherosclerotic plaques from a human carotid and mouse aortic sinuses, we describe 3D reconstruction methods using open-source software that provides high-quality visualization and rapid interpretation through multivariate segmentation of the 3D IMS data. Multiple datasets were generated for each sample and we provide insight into simple means to correlate the separate datasets.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/pmic.201500490DOI Listing
June 2016

Surface Plasmon Resonance Imaging-MALDI-TOF Imaging Mass Spectrometry of Thin Tissue Sections.

Anal Chem 2016 Feb 27;88(4):2072-9. Epub 2016 Jan 27.

Département de Chimie, Université de Montréal , C.P. 6128 Succ. Centre-Ville, Montréal, Québec H3C 3J7, Canada.

Identification and quantification of proteins in imaging of biological samples are a challenge in today's science. Here, we demonstrate a novel surface plasmon resonance imaging-matrix assisted laser desorption ionization imaging mass spectrometry (SPRi-MALDI IMS) coupled technique competent for the acquisition of multiparametric information by creating a tissue section imprint on an SPRi sensor surface. Correlated images were acquired in SPRi and in MALDI IMS for abundant proteins from a single mouse kidney tissue. The spatial organization of the transferred proteins from the tissue to the SPRi surface was preserved and imaged by SPR and MALDI MS. Surface chemistry was selected to nonspecifically adsorb and retain high concentrations of proteins on the SPRi surface. The diffusion kinetics were controlled to ensure fast transfer of proteins from the tissue sections with minimal lateral diffusion to achieve high spatial fidelity transfer. Lastly, the SPRi instrument was modified to insert a tissue sample in the fluidics chamber to facilitate the real-time measurement of the transfer process. The MALDI IMS experimental conditions, such as matrix deposition and the interface between the SPRi prism and the MALDI IMS instrument, were also optimized. The results show quantitative and regioselective SPRi images correlating to MALDI IMS images of different proteins transferred from a single tissue section.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.analchem.5b03309DOI Listing
February 2016

Introducing specificity and sensitivity in imaging MS.

Authors:
Pierre Chaurand

Bioanalysis 2015 Sep 17;7(18):2279-2281. Epub 2015 Sep 17.

Department of Chemistry, Université de Montréal, Montreal QC, Canada.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.4155/bio.15.160DOI Listing
September 2015

Aberrant Lipid Metabolism in the Forebrain Niche Suppresses Adult Neural Stem Cell Proliferation in an Animal Model of Alzheimer's Disease.

Cell Stem Cell 2015 Oct 27;17(4):397-411. Epub 2015 Aug 27.

Research Center of the University of Montreal Hospital (CRCHUM), Montreal, QC H2X 0A9, Canada; CNS Research Group (GRSNC), Montreal, QC H3T 1J4, Canada; Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada. Electronic address:

Lipid metabolism is fundamental for brain development and function, but its roles in normal and pathological neural stem cell (NSC) regulation remain largely unexplored. Here, we uncover a fatty acid-mediated mechanism suppressing endogenous NSC activity in Alzheimer's disease (AD). We found that postmortem AD brains and triple-transgenic Alzheimer's disease (3xTg-AD) mice accumulate neutral lipids within ependymal cells, the main support cell of the forebrain NSC niche. Mass spectrometry and microarray analyses identified these lipids as oleic acid-enriched triglycerides that originate from niche-derived rather than peripheral lipid metabolism defects. In wild-type mice, locally increasing oleic acid was sufficient to recapitulate the AD-associated ependymal triglyceride phenotype and inhibit NSC proliferation. Moreover, inhibiting the rate-limiting enzyme of oleic acid synthesis rescued proliferative defects in both adult neurogenic niches of 3xTg-AD mice. These studies support a pathogenic mechanism whereby AD-induced perturbation of niche fatty acid metabolism suppresses the homeostatic and regenerative functions of NSCs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.stem.2015.08.001DOI Listing
October 2015

Acute amnestic encephalopathy in amyloid-β oligomer-injected mice is due to their widespread diffusion in vivo.

Neurobiol Aging 2015 Jun 16;36(6):2043-52. Epub 2015 Mar 16.

Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Inserm, U 1127, CNRS UMR 7225, ICM, Paris, France.

Amyloid-β (Aβ) oligomers are the suspected culprit as initiators of Alzheimer's disease (AD). However, their diffusion in the brain remains unknown. Here, we studied Aβ oligomers' dissemination and evaluated their in vivo toxicity. Wild-type mice were injected with 50 pmol of synthetic Aβ oligomers (of different size) in the hippocampus. Oligomers diffused largely in the brain as soon as 1 hour and up to 7 days after injection. A transient encephalopathy with memory impairment was induced by this unique injection. The immunoreactivity of the postsynaptic marker PSD95 was diffusely decreased. Similar results (both on memory and PSD95 immunoreactivity) were obtained with delipidated and high molecular weight oligomers (>50 kDa) but not with smaller assemblies. Tau hyperphosphorylation was observed in the oligomer-injected brains. Finally, fos immunostaining was increased in Aβ-derived diffusible ligands-injected mice, suggesting neuronal hyperactivity. Rapid and widespread diffusion of Aβ oligomers was demonstrated in vivo and associated with decreased synaptic markers and memory deficits which gives new insight to the pathogenicity of Aβ.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.neurobiolaging.2015.03.005DOI Listing
June 2015

Development of laser desorption imaging mass spectrometry methods to investigate the molecular composition of latent fingermarks.

J Am Soc Mass Spectrom 2015 Jun 7;26(6):878-86. Epub 2015 Apr 7.

Department of Chemistry, Université de Montréal, C.P. 6128, Succursale Centre-ville, Montréal, Québec, H3C 3J7, Canada.

For a century, fingermark analysis has been one of the most important and common methods in forensic investigations. Modern chemical analysis technologies have added the potential to determine the molecular composition of fingermarks and possibly identify chemicals a suspect may have come into contact with. Improvements in analytical detection of the molecular composition of fingermarks is therefore of great importance. In this regard, matrix-assisted laser desorption ionization (MALDI) and laser desorption ionization (LDI) imaging mass spectrometry (IMS) have proven to be useful technologies for fingermark analysis. In these analyses, the choice of ionizing agent and its mode of deposition are critical steps for the identification of molecular markers. Here we propose two novel and complementary IMS approaches for endogenous and exogenous substance detection in fingermarks: sublimation of 2-mercaptobenzothiazol (2-MBT) matrix and silver sputtering.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s13361-015-1123-0DOI Listing
June 2015

In search of the molecular mechanisms mediating the inhibitory effect of the GnRH antagonist degarelix on human prostate cell growth.

PLoS One 2015 26;10(3):e0120670. Epub 2015 Mar 26.

The Research Institute of the McGill University Health Center, Montréal, Québec, Canada; Department of Medicine, McGill University, Montréal, Québec, Canada; Departments of Biochemistry, McGill University, Montréal, Québec, Canada; Department of Pharmacology and Therapeutics, McGill University, Montréal, Québec, Canada.

Degarelix is a gonadrotropin-releasing hormone (GnRH) receptor (GnRHR) antagonist used in patients with prostate cancer who need androgen deprivation therapy. GnRHRs have been found in extra-pituitary tissues, including prostate, which may be affected by the GnRH and GnRH analogues used in therapy. The direct effect of degarelix on human prostate cell growth was evaluated. Normal prostate myofibroblast WPMY-1 and epithelial WPE1-NA22 cells, benign prostatic hyperplasia (BPH)-1 cells, androgen-independent PC-3 and androgen-dependent LNCaP prostate cancer cells, as well as VCaP cells derived from a patient with castration-resistant prostate cancer were used. Discriminatory protein and lipid fingerprints of normal, hyperplastic, and cancer cells were generated by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). The investigated cell lines express GNRHR1 and GNRHR2 and their endogenous ligands. Degarelix treatment reduced cell viability in all prostate cell lines tested, with the exception of the PC-3 cells; this can be attributed to increased apoptosis, as indicated by increased caspase 3/7, 8 and 9 levels. WPE1-NA22, BPH-1, LNCaP, and VCaP cell viability was not affected by treatment with the GnRH agonists leuprolide and goserelin. Using MALDI MS, we detected changes in m/z signals that were robust enough to create a complete discriminatory profile induced by degarelix. Transcriptomic analysis of BPH-1 cells provided a global map of genes affected by degarelix and indicated that the biological processes affected were related to cell growth, G-coupled receptors, the mitogen-activated protein kinase (MAPK) pathway, angiogenesis and cell adhesion. Taken together, these data demonstrate that (i) the GnRH antagonist degarelix exerts a direct effect on prostate cell growth through apoptosis; (ii) MALDI MS analysis provided a basis to fingerprint degarelix-treated prostate cells; and (iii) the clusters of genes affected by degarelix suggest that this compound, in addition to its known use in the treatment of prostate cancer, may be efficacious in BPH.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0120670PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4374753PMC
March 2016

Increasing specificity in imaging mass spectrometry: high spatial fidelity transfer of proteins from tissue sections to functionalized surfaces.

Anal Bioanal Chem 2015 Mar 9;407(8):2159-66. Epub 2014 Nov 9.

Department of Chemistry, Université de Montréal, C.P. 6128, succursale Centre-ville, Montréal, QC, H3T 1J4, Canada.

Imaging mass spectrometry (IMS) is a technique in full expansion used in many clinical and biological applications. A common limitation of the technology, particularly true for protein analysis, is that only the most abundant and/or more easily ionizable molecules are typically detected. One approach to overcome this limitation is to transfer proteins contained within tissue sections onto functionalized surfaces with high spatial fidelity for IMS analysis. In this case, only proteins with an affinity for the surface will be retained whereas others will be removed. The chemical nature of the surface is therefore critical. The research work presented herein proposes a high spatial fidelity transfer method for proteins from thin tissue sections onto a nitrocellulose surface. The method employs a home-built apparatus that allows the transfer process to be performed without any direct physical contact between the section and the transfer surface while maintaining physical pressure between the surfaces to help protein migration. The performance of this system was demonstrated using mouse liver and kidney sections. Serials sections were also collected either to be stained with hematoxylin and eosin (H&E) to assess the spatial fidelity of the transfer process or to be directly analyzed as a control sample to differentiate the signals detected after transfer. IMS results showed a high spatial fidelity transfer of a subset of proteins. Some of the detected proteins were poorly observed or not observed with conventional direct tissue analysis, demonstrating an increase in detection sensitivity and specificity with the newly developed method.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00216-014-8300-zDOI Listing
March 2015

Unravelling nonspecific adsorption of complex protein mixture on surfaces with SPR and MS.

Anal Chem 2014 Oct 15;86(19):9612-9. Epub 2014 Sep 15.

Département de Chimie, Université de Montréal , C.P. 6128 Succursale Centre-Ville, Montreal, Quebec Canada , H3C 3J7.

Characterization of protein adsorption to surfaces has implications from biosensing to protective biocoatings. While research studies have principally focused on determining the magnitude of protein adsorption to surfaces, the proteins involved in the process remains only broadly identified and has not been investigated on several surfaces. To further elucidate the nonspecific adsorption process of serum to surfaces, surface plasmon resonance (SPR) and matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) were used in combination to obtain quantitative and qualitative information about the process of protein adsorption to surfaces. To validate the technique, crude serum was nonspecifically adsorbed on four self-assembled monolayer (SAM) on gold: 16-mercaptohexadecanoic acid (16-MHA), 11-mercaptoundecane(ethylene glycol)3-COOH (PEG), 3-MPA-LHDLHD-OH, and 3-MPA-HHHDD-OH. Direct MS analysis of the nonspecifically adsorbed proteins suggested the presence of a variety of protein (BSA, IgG, and apolipoprotein A-1). Performing a trypsin digestion of the nonspecifically adsorbed proteins confirmed the presence of BSA and apolipoprotein A-1 and further revealed the complexity of the process by detecting the presence of complement C3, SHC-transforming protein 1, and kininogen 2. The level of nonspecific adsorption on different surfaces measured by SPR sensing directly correlated with the intensity of the serum protein and indirectly with the tryptic peptides measured by MS. Detailed analysis of the BSA peptides digested on 16-MHA and for BSA digested in solution was used to investigate the orientation of BSA on this surface. The combination of SPR and MS allows the quantitative and qualitative understanding of protein adsorption processes to surfaces.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ac502077bDOI Listing
October 2014

Monitoring time-dependent degradation of phospholipids in sectioned tissues by MALDI imaging mass spectrometry.

J Mass Spectrom 2014 Jul;49(7):622-7

Department of Chemistry, University of Montreal, Montreal, Quebec, Canada.

Imaging mass spectrometry (IMS) is useful for visualizing the localization of phospholipids on biological tissue surfaces creating great opportunities for IMS in lipidomic investigations. With advancements in IMS of lipids, there is a demand for large-scale tissue studies necessitating stable, efficient and well-defined sample handling procedures. Our work within this article shows the effects of different storage conditions on the phospholipid composition of sectioned tissues from mouse organs. We have taken serial sections from mouse brain, kidney and liver thaw mounted unto ITO-coated glass slides and stored them under various conditions later analyzing them at fixed time points. A global decrease in phospholipid signal intensity is shown to occur and to be a function of time and temperature. Contrary to the global decrease, oxidized phospholipid and lysophospholipid species are found to increase within 2 h and 24 h, respectively, when mounted sections are kept at ambient room conditions. Imaging experiments reveal that degradation products increase globally across the tissue. Degradation is shown to be inhibited by cold temperatures, with sample integrity maintained up to a week after storage in -80 °C freezer under N2 atmosphere. Overall, the results demonstrate a timeline of the effects of lipid degradation specific to sectioned tissues and provide several lipid species which can serve as markers of degradation. Importantly, the timeline demonstrates oxidative sample degradation begins appearing within the normal timescale of IMS sample preparation of lipids (i.e. 1-2 h) and that long-term degradation is global. Taken together, these results strengthen the notion that standardized procedures are required for phospholipid IMS of large sample sets, or in studies where many serial sections are prepared together but analyzed over time such as in 3-D IMS reconstruction experiments.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jms.3382DOI Listing
July 2014

Acyl-coenzyme A-binding protein regulates Beta-oxidation required for growth and survival of non-small cell lung cancer.

Cancer Prev Res (Phila) 2014 Jul 12;7(7):748-57. Epub 2014 May 12.

Division of Allergy, Pulmonary and Critical Care Medicine, Departments of Veterans Affairs Medical Center, Nashville, Tennessee; and

We identified acyl-coenzyme A-binding protein (ACBP) as part of a proteomic signature predicting the risk of having lung cancer. Because ACBP is known to regulate β-oxidation, which in turn controls cellular proliferation, we hypothesized that ACBP contributes to regulation of cellular proliferation and survival of non-small cell lung cancer (NSCLC) by modulating β-oxidation. We used matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS) and immunohistochemistry (IHC) to confirm the tissue localization of ABCP in pre-invasive and invasive NSCLCs. We correlated ACBP gene expression levels in NSCLCs with clinical outcomes. In loss-of-function studies, we tested the effect of the downregulation of ACBP on cellular proliferation and apoptosis in normal bronchial and NSCLC cell lines. Using tritiated-palmitate ((3)H-palmitate), we measured β-oxidation levels and tested the effect of etomoxir, a β-oxidation inhibitor, on proliferation and apoptosis. MALDI-IMS and IHC analysis confirmed that ACBP is overexpressed in pre-invasive and invasive lung cancers. High ACBP gene expression levels in NSCLCs correlated with worse survival (HR = 1.73). We observed a 40% decrease in β-oxidation and concordant decreases in proliferation and increases in apoptosis in ACBP-depleted NSCLC cells as compared with bronchial airway epithelial cells. Inhibition of β-oxidation by etomoxir in ACBP-overexpressing cells produced dose-dependent decrease in proliferation and increase in apoptosis (P = 0.01 and P < 0.001, respectively). These data suggest a role for ACBP in controlling lung cancer progression by regulating β-oxidation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1158/1940-6207.CAPR-14-0057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4090029PMC
July 2014