Subscriber access provided by EKU Libraries
Article
Mass Spectrometry Imaging of Brain Cholesterol and Metabolites with Trifluoroacetic Acid-Enhanced Desorption Electrospray Ionization Xiaoqun Wang, Yiwen Hou, Zhuanghao Hou, Wei Xiong, and Guangming Huang Anal. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.analchem.8b04395 • Publication Date (Web): 15 Jan 2019 Downloaded from http://pubs.acs.org on January 16, 2019
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 9 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Analytical Chemistry
Mass Spectrometry Imaging of Brain Cholesterol and Metabolites with Trifluoroacetic Acid-Enhanced Desorption Electrospray Ionization Xiaoqun Wang,§,ǁ Yiwen Hou,†,ǁ Zhuanghao Hou,§ Wei Xiong,†,‡,* and Guangming Huang§,* §Department
of Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China, Hefei Anhui, 230026, P. R. China †School
of Life Sciences, Neurodegenerative Disorder Research Center, University of Science and Technology of China, Hefei Anhui, 230026, P. R. China ‡Center
for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031,
China ABSTRACT: Imaging of cholesterol and other metabolites simultaneously by ambient mass spectrometry will greatly benefit biological studies, however, it still remains challenging. Herein, by adding acid into the desorption electrospray ionization (DESI) spray solvent, we achieved simultaneous mass spectrometry imaging of cholesterol and other metabolites directly from mouse brain sections. The introduction of acid increased the signal intensity of cholesterol in mouse brain tissues by approximately 21-fold. Additionally, present strategy provided increased signal intensities for other metabolites up to 62-folds, as well as identification of seven more metabolites (23 vs 16 for acid enhanced DESI vs DESI). Moreover, increased corelationships for alanine as well as putrescine and spermidine with cholesterol were discovered under acid enhanced DESI. The potential of the present strategy in the fields of biological and medical research was demonstrated by investigating the level change for cholesterol, alanine, putrescine, and spermidine in Alzheimer’s disease (AD) mouse brain.
Endogenous cholesterol in brain is currently gaining increased recognition due to its role in multiple brain neurological diseases, such as Alzheimer’s disease (AD).1 Creating a detailed map of brain cholesterol helps to better understand the pathophysiological mechanisms, and the map is normally achieved by mass spectrometry imaging (MSI) techniques. Although matrix-assisted laser desorption ionization (MALDI),2,3 laser desorption ionization (LDI),4 and secondary ion MS (SIMS)5,6 have been widely applied in this area, some major drawbacks such as ion suppression effect and frequent fragments have greatly limited their applications in the cholesterol imaging.7 Desorption electrospray ionization (DESI) has been developed for direct MSI due to its less ion suppression effect and less fragment problem.8,9 However, cholesterol is not readily ionized by the DESI because of its low proton affinity and low acidity.10 To address this issue, precharged “betaine aldehyde” was used as the derivatization reagent for DESI imaging to map endogenous cholesterol in rat brain, atheroma and porcine adrenal gland tissues.11-13
However, this technique restricted the simultaneous detection of other underivatized analytes such as metabolites. Several evidences revealed that improper regulation of small metabolites (m/z < 300) in the brain has also been implicated in various human brain diseases including AD.14-16 Therefore, simultaneous detection of cholesterol and other metabolites in the brain will be beneficial for understanding pathophysiological mechanisms. Currently, direct imaging of metabolites in brain tissue was achieved by DESI MS17-19 and nano-DESI MS.20 Improved sensitivity for small metabolites was further achieved by using off-line derivatization method with tedious sample preparation.21 Thus, direct DESI-MS for simultaneous imaging of cholesterol and other metabolites in the brain remains challenging. Volatile acid as a proton supplier was often added to the DESI spray solvent to enhance the ionization efficiency of different types of analytes in tissue samples. For example, acetic acid and formic acid were used for analysis of polar lipids, such as sphingomyelin, glycerophosphocholine, and lysoglycerophosphocholines.12,22,23 The use of hydrochloric
ACS Paragon Plus Environment
Analytical Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
acid enhanced the detection of cholesterol present in human lens tissue.24 However, acid additive has yet to be demonstrated for simultaneous DESI MS imaging of cholesterol and other metabolites in the brain. In this study, we utilized acid additive to improve the DESI MS detection sensitivity for cholesterol and other metabolites in the brain tissue simultaneously. This improvement was achieved by obtaining more protons from acid to improve their ionization efficiency. Importantly, this strategy revealed the biologically relevant correlation between cholesterol and other metabolites in the brain. Using this approach, we explored the level changes of cholesterol and other metabolites in the brain tissues of AD mouse compared to control mouse, suggesting the potential application in neuroscience and other fields.
EXPERIMENTAL SECTION Chemicals and Reagents. Cholesterol standard (95% purity) was purchased from J&K Scientific Ltd. (Beijing, China). Formic acid (FA, 99.8% purity) was obtained from Sigma-Aldrich Chemical Co., Ltd. (U.S.A.). Trifluoroacetic acid (TFA, 99.5% purity) and trichloroacetic acid (TCA, 99.0% purity) were purchased from Aladdin Chemistry Co., Ltd. (Shanghai, China). Hydrochloric acid (HCl, ∼37% purity) and nitric acid (HNO3, ∼66% purity) were obtained from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). High performance liquid chromatography grade methanol (MeOH) was purchased from Honeywell Burdick & Jackson Inc. (U.S.A.). All chemicals and reagents were used directly without any further purification. Polytetrafluoretyhylene (PTFE) substrate of 1 mm thick was purchased from ShenZhen Anceley Insulated Plastic Material Co., Ltd. Animals. All animal experiment procedures were approved by the Institutional Animal Care and Use Committee of the University of Science and Technology of China (USTC). All animals were housed on a 12:12 h light–dark cycle and had access to water and a standard laboratory diet ad libitum. After mice were kept under isoflurane anaesthesia for 30 s, brain was quickly removed from the mouse body and immediately frozen at -80 °C until use. Mouse 1 to 4 (C57BL/6J, 8 weeks old) were purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd. (Beijing, China). Brain homogenates from mouse 1 were used to evaluate the new acid candidate. Brain tissues from mouse 2, 3, and 4 were imaged by DESI-MS with and without acid additive. Sixmonth-old 5xFAD model mouse (mouse 5, 6, and 7) and age-matched wild-type counterpart (WT, mouse 8, 9, and 10) were obtained by crossing 5xFAD hemizygous males
on C57BL/6J background with wild type C57BL/6J females (Jackson Laboratory, Bar Harbor, ME, USA). Preparation of mouse brain homogenates. Whole frozen mouse brain was weighed and then homogenized with ultrasonic cell disruptor (Ningbo Scientz Biotechnology Co., Ltd, JY 92-IIDN) in sterile water (50 mg tissue/mL). The homogenates were dispensed to 1 mL aliquots used for single measurement and then stored at -80 °C until DESI-MS analysis. Prior to analysis, the homogenates thawed at room temperature for at least 30 min. Tissue Sectioning. Mouse tissues were fixed on a stage using Optimal Cutting Temperature compound (Sakura Finetek Japan, Tokyo) and equilibrated at −20 °C in the cryostat (1860, Leica Biosystems Inc., Buffalo Grove, IL). Tissue was cut into 15 μm thick and thaw-mounted on adhesive microscope slides (Citoglas, Jiangsu, China). The slicing of the brain tissue was performed at ca. 2.04 mm according to Lateral coordinates. Tissue sections were analyzed immediately following preparation. Slices of AD model 5xFAD and the corresponding WT mouse brain were placed on the same glass for DESI-MSI analysis. DESI Analysis. DESI-MS and DESI-MSI analysis were both performed on an Exactive Plus mass spectrometer (Thermo Scientific, San Jose, CA, USA), and DESIMS/MS was conducted with an LTQ mass spectrometer (Thermo Scientific, San Jose, CA, USA). Mass spectrometer was equipped with a home-built DESI ion source, which consisted of an inner capillary (50 µm i.d., 150 µm o.d.) for delivering the spray solvent and an outer capillary (250 µm i.d., 365 µm o.d.) for delivering nitrogen nebulizing gas. A sprayer-to-surface distance of 1.5 mm, a sprayer-to-inlet distance of 6 mm, a spray impact angle of 55°, and a collection angle of 0.05), 5xFAD mouse had increased levels of spermidine in the medulla, pons, midbrain, superior colliculus, and cerebral peduncle along with markedly decreased levels of spermidine in hypothalamus (Figure 6D and G). This finding of changes in putrescine and spermidine level in AD brain may provide a new research direction in the AD research field, since putrescine and spermidine as polyamines had important roles in modulating learning and memory and maintaining normal cellular function.45 The 5xFAD mouse had increased levels of alanine in cerebellum, hippocampus, thalamus, cerebral peduncle, striatum, corpus callosum, visual cortex, and insular cortex compared to WT mouse (Figure S8A and C). Consistently, this increase was also found in the striatum of CRND8 transgenic AD mouse model.46 Compared with WT mice, the 5xFAD mice exhibited increased expression of creatine in the cerebellum, spinal cord, hippocampus, thalamus, striatum, and insular cortex (Figure S8B and D). All these results indicated the strength of acid-enhanced DESI-MSI for simultaneously tracking level changes of cholesterol and metabolites in the brain, enabling the possibility of searching potential biomarkers for AD.
CONCLUSION In conclusion, introducing acid into DESI spray solvent allowed simultaneous mapping of cholesterol and more metabolites directly in mouse brain tissue slices. This strategy produced about 21- and 62-fold increases in the average intensities of cholesterol and other metabolites in mouse brain slices, respectively, compared to DESI. Additionally, the use of acid enabled the imaging of aspartic acid, glutamic acid, hypoxanthine, NAA,
Page 8 of 9
phosphocholine, and spermine directly from mouse brain tissue by DESI-MS. Correlation between the distributions of some metabolites (i.e. alanine, putrescine, and spermidine) and cholesterol was revealed with present method. The ability to successfully analyze the level changes of cholesterol and other metabolites between control and Alzheimer’s disease (AD) mouse brain implied its potential in the fields of biological and medical researches.
ASSOCIATED CONTENT Supporting Information Supporting information includes additional experimental section, figures (Figure S1-S8), and tables (Table S1 and S2). This material is available free of harge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION Corresponding Authors *E-mail:
[email protected] (G.H.)
[email protected] (W.X.). ORCID Guangming Huang: 0000-0002-8391-4013 Wei Xiong: 0000-0002-1585-3749 Notes ǁ X. W. and Y. H. contributed equally. The authors declare no competing financial interests.
and
ACKNOWLEDGMENT We acknowledge support from National Natural Science Foundation of China (Grants 21775143 & 21475121 to G.H. and 91849206, 91649121 & 31471014 to W.X.,), the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant XDPB10), National Key R&D Program of China (2016YFC1300500-2), the Major/Innovative Program of Development Foundation of Hefei Center for Physical Science and Technology (2017FXZY006 to W.X. and 2017FXCX003 to G.H.), the Fundamental Research Funds for the Central Universities, and Users with Excellence Project of Hefei Science Center CAS.
REFERENCES (1) Sun, J. H.; Yu, J. T.; Tan, L. Mol. Neurobiol. 2015, 51, 947–965. (2) Zhou, D.; Guo, S.; Zhang, M.; Liu, Y.; Chen, T.; Li, Z. Anal. Chim. Acta 2017, 962, 52–59. (3) Ellis, S. R.; Soltwisch, J.; Paine, M. R. L.; Dreisewerd, K.; Heeren, R. M. A. Chem. Commun. 2017, 53, 7246–7249. (4) Dufresne, M.; Thomas, A.; Breault–Turcot, J.; Masson, J. F.; Chaurand, P. Anal. Chem. 2013, 85, 3318–3324. (5) Lazar, A. N.; Bich, C.; Panchal, M.; Desbenoit, N.; Petit, V. W.; Touboul, D.; Dauphinot, L.; Marquer, C.; Laprévote, O.; Brunelle, A. Acta. Neuropathol. 2013, 125, 133–144.
ACS Paragon Plus Environment
Page 9 of 9 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Analytical Chemistry (6) Zanni, G.; Michno, W.; Di Martino, E.; Tjärnlund–Wolf, A.; Pettersson, J.; Mason, C. E.; Hellspong, G.; Blomgren, K.; Hanrieder, J. Sci. Rep. 2017, 7, 40726. (7) Taylor, A.; Dexter, A.; Bunch, J. Anal. Chem. 2018, 90, 5637–5645. (8) Wiseman, J. M.; Ifa, D. R.; Song, Q.; Cooks, R. G. Angew. Chem. Int. Edit. 2006, 45, 7188–7192. (9) Lostun, D.; Perez, C. J.; Licence, P.; Barrett, D. A.; Ifa, D. R. Anal. Chem. 2015, 87, 3286−3293. (10) Johnson, D. W.; Ten Brink, H.; Jakobs, C. J. Lipid Res. 2001, 42, 1699–1705. (11) Wu, C.; Ifa, D. R.; Manicke, N. E.; Cooks, R. G. Anal. Chem. 2009, 81, 7618–7624. (12) Manicke, N. E.; Nefliu, M.; Wu, C.; Woods, J. W.; Reiser, V.; Hendrickson, R. C.; Cooks, R. G. Anal. Chem. 2009, 81, 8702–8707. (13) Wu, C.; Ifa, D. R.; Manicke, N. E.; Cooks, R. G. Analyst 2010, 135, 28–32. (14) Hensley, K.; Hall, N.; Subramaniam, R.; Cole, P.; Harris, M.; Aksenov, M.; Aksenova, M.; Gabbita, S. P.; Wu, J. F.; Carney, J. M. J. Neurochem. 1995, 65, 2146–2156. (15) Morrison, L. D.; Kish, S. J. Neurosci. Lett. 1995, 197, 5–8. (16) Hansen, L. A.; DeTeresa, R.; Davies, P.; Terry, R. D. Neurology 1988, 38, 48–48. (17) Fernandes, A. M. A.; Vendramini, P. H.; Galaverna, R.; Schwab, N. V.; Alberici, L. C.; Augusti, R.; Castilho, R. F.; Eberlin, M. N. J. Am. Soc. Mass Spectrom. 2016, 27, 1944–1951. (18) Banerjee, S.; Zare, R. N.; Tibshirani, R. J.; Kunder, C. A.; Nolley, R.; Fan, R.; Brooks, J. D.; Sonn, G. A. Proc. Natl. Acad. Sci. U. S. A. 2017, 114, 3334–3339. (19) Jarmuscha, A. K.; Pirroa, V.; Bairda, Z.; Hattabb, E. M.; CohenGadolc, A. A.; Cooks R. G. Proc. Natl. Acad. Sci. U. S. A. 2016, 113, 1486–1491. (20) Bergman, H. M.; Lundin, E.; Andersson, M.; Lanekoff, I. Analyst 2016, 141, 3686–3695. (21) Shariatgorji, M.; Strittmatter, N.; Nilsson, A.; Kallback, P.; Alvarsson, A.; Zhang, X.; Vallianatou, T.; Svenningsson, P.; Goodwin, R. J.; Andren, P. E. Neuroimage 2016, 136, 129–138. (22) Wiseman, J. M.; Puolitaival, S. M.; Takáts, Z.; Cooks, R. G.; Caprioli, R. M. Angew. Chem. 2005, 117, 7256–7259; Angew. Chem. Int. Ed. 2005, 44, 7094–7097. (23) Basile, F.; Sibray, T.; Belisle, J. T.; Bowen, R. A. Anal. Biochem. 2011, 408, 289–296. (24) Ellis, S. R.; Wu, C.; Deeley, J. M.; Zhu, X.; Truscott, R. J.; in het Panhuis, M.; Cooks, R. G.; Mitchell, T. W.; Blanksby, S. J. J. Am. Soc. Mass Spectrom. 2010, 21, 2095–2104. (25) Garza, K. Y.; Feider, C. L.; Klein, D. R.; Rosenberg, J. A.; Brodbelt, J. S.; Eberlin, L. S. Anal. Chem. 2018, 90, 7785–7789. (26) Campbell, D. I.; Ferreira, C. R.; Eberlin, L. S.; Cooks, R. G. Anal. Bioanal. Chem. 2012, 404, 389–398. (27) Comi, T. J.; Ryu, S. W.; Perry, R.H. Anal. Chem. 2016, 88, 1169– 1175. (28) Shrivas, K.; Hayasaka, T.; Sugiura, Y.; Setou, M. Anal. Chem. 2011, 83, 7283–7289. (29) Shariatgorji, M.; Nilsson, A.; Goodwin, R. J. A.; Svenningsson, P.; Schintu, N.; Banka, Z.; Kladni, L.; Hasko, T.; Szabo, A.; Andren, P. E. Anal. Chem. 2012, 84, 7152−7157. (30) Feider, C. L.; Elizondo, N.; Eberlin, L. S. Anal. Chem. 2016, 88, 11533−11541. (31) Luo, Z.; He, J.; Chen, Y.; He, J.; Gong, T.; Tang, F.; Wang, X.; Zhang, R.; Huang, L.; Zhang, L.; Lv, H.; Ma, S.; Fu, Z.; Chen, X.; Yu, S.; Abliz, Z. Anal. Chem. 2013, 85, 2977−2982. (32) He, J.; Luo, Z.; Huang, L.; He, J.; Chen, Y.; Rong, X.; Jia, S.; Tang, F.; Wang, X.; Zhang, R.; Zhang, J.; Shi, J.; Abliz, Z. Anal. Chem. 2015, 87, 5372−5379. (33) Swales, J. G., Tucker, J. W., Strittmatter, N.; Nilsson, A.; Cobice, D.; Clench, M. R.; Mackay, C. L.; Andren, P. E.; Takats, Z.; Webborn, P. J.; Goodwin, R. J. Anal. Chem. 2014, 86, 8473−8480. (34) Mascini, N. E.; Cheng, M.; Jiang, L.; Rizwan, A.; Podmore, H.; Bhandari, D. R.; Rompp, A.; Glunde, K.; Heeren, R. M. A. Anal. Chem. 2016, 88, 3107−3114. (35) Zafra, F.; Aragon, C.; Olivares, L.; Danbolt, N. C.; Gimenez, C.; Storm-Mathisen, J. J. Neurosci. 1995, 15, 3952–3969. (36) Nemes, P.; Woods, A. S.; Vertes, A. Anal. Chem. 2010, 82, 982–988. (37) Phillis, J. W.; Kostopoulos, G. K.; Limacher, J. J. Eur. J. Pharmacol. 1975, 30, 125–129.
(38) Cutler, R. G.; Kelly, J.; Storie, K.; Pedersen, W. A.; Tammara, A.; Hatanpaa, K.; Troncoso, J. C.; Mattson, M. P. Proc. Natl. Acad. Sci. U. S. A. 2004, 101, 2070–2075. (39) Puglielli, L.; Tanzi, R. E.; Kovacs, D. M. Nat. Neurosci. 2003, 6, 345. (40) Xiong, H.; Callaghan, D.; Jones, A.; Walker, D. G.; Lue, L.–F.; Beach, T. G.; Sue, L. I.; Woulfe, J.; Xu, H.; Stanimirovic, D. B. Neurobiol. Dis. 2008, 29, 422–437. (41) Mori, T.; Paris, D.; Town, T.; Rojiani, A. M.; Sparks, D. L.; Delledonne, A.; Crawford, F.; Abdullah, L. I.; Humphrey, J. A.; Dickson, D. W.; Mullan, M. J. J. Neuropathol. Exp. Neurol. 2001, 60, 778–785. (42) Mu, Y.; Gage, F. H. Mol. Neurodegener. 2011, 6, 85. (43) Ferreri, F.; Pauri, F.; Pasqualetti, P.; Fini, R.; Dal Forno, G.; Rossini, P. M. Ann. Neurol. 2003, 53, 102–108. (44) González–Domínguez, R.; García–Barrera T.; Gómez–Ariza, J. L. J. Pharm. Biomed. Anal. 2014, 98, 321–326. (45) Liu, P.; Gupta, N.; Jing, Y.; Zhang, H. Neuroscience 2008, 155, 789– 796. (46) Salek, R. M.; Xia, J.; Innes, A.; Sweatman, B. C.; Adalbert, R.; Randle, S.; McGowan, E.; Emson, P. C.; Griffin, J. L. Neurochem. Int. 2010, 56, 937–947.
ACS Paragon Plus Environment
