title: A novel cholinergic epithelial cell with chemosensory traits in the murine conjunctiva.
abstract: We recently identified a specialized cholinergic cell type in tracheal and urethral epithelium that utilizes molecules of the canonical taste transduction signaling cascade to sense potentially harmful substances in the luminal content. Upon stimulation, this cell initiates protective reflexes. Assuming a sentinel role of such cells at mucosal surfaces exposed to bacteria, we hypothesized their occurrence also in ocular mucosal surfaces. Utilizing a mouse strain expressing eGFP under the promoter of the acetylcholine synthesizing enzyme, choline acetyltransferase (ChAT-eGFP), we observed a cholinergic cell in the murine conjunctiva. Singular cholinergic cells reaching the epithelial surface with slender processes were detected in fornical, but neither in bulbar nor palpebral epithelia. These cells were found neither in the lacrimal canaliculi, nor in the lacrimal sac and the nasolacrimal duct. Cholinergic conjunctival epithelial cells were immunoreactive for components of the canonical taste transduction signaling cascade, i.e. α-gustducin, phospholipase Cβ2 and the monovalent cation channel TRPM5. Calcitonin gene-related peptide- and substance P-immunoreactive sensory nerve fibers were observed extending into the conjunctival epithelium approaching slender ChAT-eGFP-positive cells. In addition, we noted both ChAT-eGFP expression and α-gustducin-immunoreactivity, albeit in different cell populations, in occasionally occurring lymphoid follicles of the nictitating membrane. The data show a previously unidentified cholinergic cell in murine conjunctiva with chemosensory traits that presumably utilizes acetylcholine for signaling. In analogy to similar cells described in the respiratory and urethral epithelium, it might serve to detect bacterial products and to initiate protective reflexes.
authors.affiliation: Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Aulweg 123, 35385, Giessen, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Wiederhold
authors.affiliation: Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Aulweg 123, 35385, Giessen, Germany.
authors.forename: Tamara
authors.initials: T
authors.lastname: Papadakis
authors.affiliation: Walter-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Chubanov
authors.affiliation: Walter-Straub-Institute for Pharmacology and Toxicology, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Gudermann
authors.affiliation: Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Aulweg 123, 35385, Giessen, Germany; Institute for Anatomy and Cell Biology, Julius-Maximilians-Universität Würzburg, Koellikerstraße 6, 97070 Würzburg, Germany.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Krasteva-Christ
authors.affiliation: Institute for Anatomy and Cell Biology, Justus-Liebig-University Giessen, Aulweg 123, 35385, Giessen, Germany. Electronic address: wolfgang.kummer@anatomie.med.uni-giessen.de.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kummer
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D002633:Chemotaxis / Q000502:physiology*; D002795:Choline O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D003228:Conjunctiva / Q000166:cytology*; D004847:Epithelial Cells / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D041722:Genes, Transgenic, Suicide; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007150:Immunohistochemistry; D051379:Mice; D011984:Sensory Receptor Cells / Q000502:physiology
chemical_list: C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D002795:Choline O-Acetyltransferase; D000109:Acetylcholine
keywords: Brush cell; Conjunctiva; Non-neuronal acetylcholine; Taste