Glial Network Responses to Polymicrobial Invasion of Dentin

Abstract

This study investigated the distribution patterns of glial networks disclosed by reactivity for glial fibrillary acidic protein (GFAP) and S100B in healthy and carious human teeth. The objective was to determine the assembly and collapse of glial networks in response to encroaching infection. 15 healthy and 37 carious posterior teeth from adults were studied. Immediately after extraction, teeth were cleaned and vertically split and the half with pulp fixed and prepared for resin or frozen sections. Sections were stained with toluidine blue and for immunofluorescence, with observation by confocal laser microscopy and analysis by ImageJ software. Carious teeth were subdivided into three groups according to degree of carious involvement: microbial penetration through enamel (stage A), extension into dentin (stage B) and advanced penetration into dentin but without invasion of underlying pulp tissue (stage C). In stage A lesions there was marked increase in glial networks in dental pulp tissue that extended beyond the zone of microbial invasion. This response was maintained in stage B lesions. In advanced stage C lesions these networks were degraded in the zone of invasion in association with failure to contain infection. Cells expressing the glial markers GFAP and S100B showed a response to initial microbial invasion of dentin by increase in number and altered anatomical arrangement. The late stage of dentinal caries was marked by collapse of these networks in the region adjacent to advancing bacteria. This behaviour is important for understanding and explaining the defensive response of the neurosensory peripheral dental pulp apparatus to infection.

Three/four-dimensional (3D/4D) microscopic imaging and processing in clinical dental research

“…The present study demonstrates that latent patterns of the increased glial cell markers GFAP and S100B on carious teeth lesions can be revealed through 3D reconstruction from thick specimens. The increased abundance of these markers in carious teeth lesions indicates a response to initial microbial invasion of dentin [5]. In the current study, 3D reconstruction also reveals strong expression of amelogenin protein in pulp cells (odontoblasts) and in dentinal tubules from adult human teeth with carious lesions.…”

“…The detailed processing of teeth has been described in the previous paper [5]. Briefly, healthy ( n  = 15) and carious teeth ( n  = 37) were obtained with approval of the Ethics Committee of Sydney West Local Health Service and informed consent from patients, aged from 20 to 45 years.…”

Schwann Cell Phenotype Changes in Aging Human Dental Pulp

“…The expression of GAP43 has been related to axonal regeneration during nerve injury (Suzuki et al 2015). SCs expressing S100 and GFAP markers become highly reactive in response to caries progression (Houshmandi et al 2014). These antecedents support the conclusion that SCs play crucial roles during tooth development and for the preservation of sensory function under pathologic conditions (Painter et al 2014).…”

Schwann Cell Responses and Plasticity in Different Dental Pulp Scenarios

“…However, the response of the pulpal glial network to caries progression has been scarcely investigated. Changes in the expression of SC markers (S100 and GFAP) in response to caries pathogens are evident at initial caries stages (Figures 2A,B ), while a major expansion of the reactive glial network occurs in response to advancing pathogen bacteria during severe dentin caries stages, indicating a dynamic pulpal reaction to control the caries advance (Houshmandi et al, 2014 ). If this response remains unsuccessful, DP inflammation mediated by caries pathogens can lead to pulpal tissue necrosis (Farges et al, 2015 ).…”