title: Cyclic mechanical pressure-loading alters epithelial homeostasis in a three-dimensional in vitro oral mucosa model: clinical implications for denture-wearers.
abstract: Denture-wearing affects the quality and quantity of epithelial cells in the underlying healthy oral mucosa. The physiologic mechanisms, however, are poorly understood. This study aimed to compare histologic changes and cellular responses of an epithelial cell layer to cyclic mechanical pressure-loading mimicking denture-wearing using an organotypic culture system to develop a three-dimensional in vitro oral mucosa model (3DOMM). Primary human oral keratinocytes and fibroblasts were serially grown in a monolayer culture, and cell viability was measured under continuous cyclic mechanical pressure (50 kPa) for 7 days (cycles of 60 min on, 20 s off to degas and inject air). Upon initiation of an air-liquid interface culture for epithelial stratification, the cyclic pressure, set to the mode above mentioned, was applied to the 3DOMMs for 7 days. Paraffin-embedded 3DOMMs were examined histologically and immunohistochemically. In the monolayer culture, the pressure did not affect the viability of oral keratinocytes or fibroblasts. Few histologic changes were observed in the epithelial layer of the control and pressure-loaded 3DOMMs. Immunohistochemical examination, however, revealed a significant decrease in Ki-67 labelling and an increase in filaggrin and involucrin expression in the suprabasal layer of the pressure-loaded 3DOMMs. Pressure-loading attenuated integrin β1 expression and increased matrix metalloproteinase-9 activity. Incomplete deposition of laminin and type IV collagen beneath the basal cells was observed only in the pressure-loaded 3DOMM. Cyclic pressure-loading appeared to disrupt multiple functions of the basal cells in the 3DOMM, resulting in a predisposition towards terminal differentiation. Thus, denture-wearing could compromise oral epithelial homeostasis.
authors.affiliation: Division of Dental Educational Research Development, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan; Division of Oral Anatomy, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Shiomi
authors.forename: K
authors.initials: K
authors.lastname: Izumi
authors.forename: A
authors.initials: A
authors.lastname: Uenoyama
authors.forename: T
authors.initials: T
authors.lastname: Saito
authors.forename: N
authors.initials: N
authors.lastname: Saito
authors.forename: H
authors.initials: H
authors.lastname: Ohnuki
authors.forename: H
authors.initials: H
authors.lastname: Kato
authors.forename: M
authors.initials: M
authors.lastname: Kanatani
authors.forename: S
authors.initials: S
authors.lastname: Nomura
authors.forename: H
authors.initials: H
authors.lastname: Egusa
authors.forename: T
authors.initials: T
authors.lastname: Maeda
mesh_terms: D024141:Collagen Type IV / Q000378:metabolism; D003778:Dentures / Q000009:adverse effects*; D004847:Epithelial Cells / Q000473:pathology*; D005347:Fibroblasts / Q000473:pathology; D000091344:Filaggrin Proteins; D006706:Homeostasis; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D007381:Intermediate Filament Proteins / Q000378:metabolism; D015603:Keratinocytes / Q000473:pathology; D019394:Ki-67 Antigen / Q000378:metabolism; D007797:Laminin / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D008954:Models, Biological; D009061:Mouth Mucosa / Q000473:pathology*; D011498:Protein Precursors / Q000378:metabolism
chemical_list: D024141:Collagen Type IV; C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D019012:Integrin beta1; D007381:Intermediate Filament Proteins; D019394:Ki-67 Antigen; D007797:Laminin; D011498:Protein Precursors; C032253:involucrin; D020780:Matrix Metalloproteinase 9
keywords: dentures; epithelial cell; fibroblast; in vitro; mouth mucosa; pressure