title: In Situ Characterization of Tissue-Resident Immune Cells by MALDI Mass Spectrometry Imaging.
abstract: Tissue-resident immune cells differ from their corresponding blood cells in many functional aspects. Although the proteome of blood immune cells has been well-investigated, there are almost no data on tissue-resident immune cells. Here, we explored the potential of using MALDI-TOF-MS imaging (MSI) to investigate these cells in colon tissue, which exhibits a strong infiltration of immune cells. MSI identified several proteinaceous markers that colocalized with specific structures of the colon, such as mucosa or muscularis mucosae, in six patients. In addition, we showed that certain m/z values have the same spatial distribution as CD3+T lymphocytes in the lymphoid follicular structures or as CD206+macrophages in the lamina propria. For further corroboration, blood lymphocytes and monocytes from 10 healthy volunteers were analyzed by intact cell mass spectrometry (ICMS). Furthermore, we analyzed monocyte-derived macrophages that had been polarized in vitro into proinflammatory M1and anti-inflammatory M2phenotypes. The mass spectra differed clearly among all immune cell types. Additionally, it was found that distinct signals from ICMS analysis were identical to the m/z values found in the MSI experiment in lymphoid follicular structures. These data show for the first time that MSI is well-suited to visualize the spatial distribution of immune cells in human colon tissue. We consider MALDI mass spectrometry imaging to be a technique with high potential for use in rapid investigations of tissue-specific features of cells.
authors.affiliation: Institute of Chemical Technologies and Analytics (CTA), TU Wien , 1060 Vienna, Austria.
authors.forename: Matthias
authors.initials: M
authors.lastname: Holzlechner
authors.affiliation: CBmed GmbH-Center for Biomarker Research in Medicine , 8020 Graz, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Strasser
authors.affiliation: Institute of Chemical Technologies and Analytics (CTA), TU Wien , 1060 Vienna, Austria.
authors.forename: Elitsa
authors.initials: E
authors.lastname: Zareva
authors.forename: Luise
authors.initials: L
authors.lastname: Steinhäuser
authors.forename: Hanna
authors.initials: H
authors.lastname: Birnleitner
authors.forename: Andrea
authors.initials: A
authors.lastname: Beer
authors.forename: Michael
authors.initials: M
authors.lastname: Bergmann
authors.forename: Rudolf
authors.initials: R
authors.lastname: Oehler
authors.affiliation: Institute of Chemical Technologies and Analytics (CTA), TU Wien , 1060 Vienna, Austria.
authors.forename: Martina
authors.initials: M
authors.lastname: Marchetti-Deschmann
mesh_terms: D002454:Cell Differentiation; D003106:Colon / Q000166:cytology* / Q000276:immunology; D006801:Humans; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000166:cytology* / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000276:immunology; D008264:Macrophages / Q000166:cytology* / Q000276:immunology; D057054:Molecular Imaging; D009000:Monocytes / Q000166:cytology* / Q000276:immunology; D009928:Organ Specificity; D025341:Principal Component Analysis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology
keywords: MALDI mass spectrometry imaging; colon tissue; immune cells; immunohistochemistry; lymphocytes; macrophages; monocytes