Comparative evaluation of neural tissue antigens--neurofilament protein (NF), peripherin (PRP), S100B protein (S100B), neuron-specific enolase (NSE) and chromogranin-A (CgA)--in both normal and inflamed human mature dental pulp

Dental Pulp Cell Transplantation Combined with Regenerative Endodontic Procedures Promotes Dentin Matrix Formation in Mature Mouse Molars

Regenerative endodontic procedures (REPs) are promising for dental pulp tissue regeneration; however, their application in permanent teeth remains challenging. We assessed the potential combination of an REP and local dental pulp cell (DPC) transplantation in the mature molars of C57BL/6 mice with (REP + DPC group) or without (REP group) transplantation of DPCs from green fluorescent protein (GFP) transgenic mice. After 4 weeks, the regenerated tissue was evaluated by micro-computed tomography and histological analyses to detect odontoblasts, vasculogenesis, and neurogenesis. DPCs were assessed for mesenchymal and pluripotency markers. Four weeks after the REP, the molars showed no signs of periapical lesions, and both the REP and REP + DPC groups exhibited a pulp-like tissue composed of a cellular matrix with vessels surrounded by an eosin-stained acellular matrix that resembled hard tissue. However, the REP + DPC group had a broader cellular matrix and uniquely contained odontoblast-like cells co-expressing GFP. Vasculogenesis and neurogenesis were detected in both groups, with the former being more prominent in the REP + DPC group. Overall, the REP was achieved in mature mouse molars and DPC transplantation improved the outcomes by inducing the formation of odontoblast-like cells and greater vasculogenesis.

Expression profiling of S100-proteins in healthy and irreversibly inflamed human dental pulps

AIM

Several S100 proteins have been shown to play an important role in the innate immune response to infection and in regenerative processes. However, they have scarcely been investigated during inflammation of the dental pulp. Therefore, in this study we performed gene expression profiling of S100 proteins in healthy and inflamed human dental pulps.

METHODOLOGY

Tissue samples of human dental pulps were used including fifteen clinically diagnosed as symptomatic irreversible pulpitis (SIP), seven as asymptomatic irreversible pulpitis (AIP), and nineteen as healthy pulp (HP). S100 gene expression levels were quantitatively evaluated for S100 A1, A2, A3, A4, A6, A7, A8, A9, A10, A11, A13, A14, and A16 by qPCR technique. In order to monitor the status of inflammation and degradation of pulp tissues, IL-8, COX-2, and HMGB-1 gene expression was also analysed, with GAPDH serving as reference gene. Differential expression rates for each target gene between SIP, AIP, and HP were evaluated by analysis of variance (ANOVA) followed by Bonferroni post-hoc-test.

RESULTS

Significantly reduced gene expression levels could be detected in SIP compared to HP for S100A1, A2, A3, A4, A6, A10, A13, and for HMGB-1, while gene expression of S100A8, A14, and IL-8 were significantly increased. In AIP, significantly increased expression levels compared to HP were only detected for S100A14, A16, and for IL-8, with other genes of interest not being altered.

CONCLUSIONS

The present study revealed significant differences in gene expression profiles of S100 proteins comparing samples from healthy and inflamed dental pulps. More pronounced differences were observed for symptomatic than for asymptomatic pulpitis.

Nell-1 promotes the neural-like differentiation of dental pulp cells

Previous studies showed that Nel-like molecule-1 (Nell-1) can positively regulate odontoblastic differentiation and dentin formation. Intriguingly, our group found that Nell-1 is co-expressed with neural markers. The purpose of this study was to investigate whether Nell-1 protein plays a regulatory role in the differentiation of dental pulp cells into neural-like cells by in vivo and in vitro studies. The expression patterns of Nell-1 and dental pulp neural markers were observed by double immunofluorescence staining in normal dental pulp tissue sections of Wistar rat. Collagen sponge containing Nell-1 protein was added into the pulp cavity of rat molars in order to observe the expression patterns of neural markers in rat dental pulp repair and regeneration model by immunohistochemical staining. Moreover, human dental pulp stem cells (hDPSCs) were cultured, and different concentrations of Nell-1 protein were added for 12 h, 24 h, and 72h. The expression of neural markers was detected by using quantitative real-time polymerase chain reaction and Western blot. Nell-1 was co-expressed with neural markers including substance P (SP) and Nestin in rat dental pulp tissue. The expression of neural markers including SP, neuron-specific enolase (NSE), and Nestin was increased obviously in rat dental pulp tissues stimulated with Nell-1 protein. In cultured hDPSCs induced by Nell-1 protein, the expression of neural markers including glial fibrillary acidic protein (GFAP), Nestin, and β-III tubulin was increased. Nell-1 plays a positive role in inducing the differentiation of DPSCs into neural-like cells.

From Mouth to Brain: Neuroendocrine Markers Play as a Crosstalk Among Oral and Neurodegenerative Diseases

The neuroendocrine system consists of various cells distributed in non-endocrine functional structures, able to synthesize amines and peptides with both local (paracrine) and systemic (endocrine) effects. The presence of such cells, belonging to the neuroendocrine system, is highlighted by the presence of neuroendocrine markers: the most suggestive are chromogranin A, synaptophysin, S-100B protein and glial fibrillary acidic protein. The presence of neuroendocrine markers is commonly associated to the occurrence of neuroendocrine cancers, currently representing the 0.5 percent of all malignant tumors. Nevertheless, neuroendocrine markers have been found to be overexpressed in rare oral neuroendocrine tumors, but also in quite common inflammatory conditions, such as severe periodontitis. The monitoring of neuroendocrine markers is, thus, a common factor of interest among dentistry and neurology: the analysis of neuroendocrine markers in oral diseases may be predictive and prognostic about the severity of neurological diseases, such as lateral amyotrophic sclerosis and traumatic brain injuries. The aim of this mini-review is to highlight the role of neuroendocrine molecules as advantageous diagnostic and prognostic markers for both oral diseases and neurodegenerative disorders.

The Role of Epigenetic Change in Autism Spectrum Disorders

Autism spectrum disorders (ASD) are a heterogeneous group of neurodevelopmental disorders characterized by problems with social communication, social interaction, and repetitive or restricted behaviors. ASD are comorbid with other disorders including attention deficit hyperactivity disorder, epilepsy, Rett syndrome, and Fragile X syndrome. Neither the genetic nor the environmental components have been characterized well enough to aid diagnosis or treatment of non-syndromic ASD. However, genome-wide association studies have amassed evidence suggesting involvement of hundreds of genes and a variety of associated genetic pathways. Recently, investigators have turned to epigenetics, a prime mediator of environmental effects on genomes and phenotype, to characterize changes in ASD that constitute a molecular level on top of DNA sequence. Though in their infancy, such studies have the potential to increase our understanding of the etiology of ASD and may assist in the development of biomarkers for its prediction, diagnosis, prognosis, and eventually in its prevention and intervention. This review focuses on the first few epigenome-wide association studies of ASD and discusses future directions.

Corticotropin releasing factor receptor expression in painful human dental pulp

BACKGROUND

Our objective was to correlate the presence of symptoms and dental pulp injury with the amount of a subtype of corticotropin releasing factor receptor (CRF-R) in symptomatic and asymptomatic human teeth. We hypothesized that patients diagnosed with irreversible pulpitis have increased levels of CRF-R.

MATERIALS AND METHODS

Dental history, diagnosis and radiographs were obtained from treatment records following extractions. Teeth were diagnosed as asymptomatic or symptomatic demonstrated by clinical and radiographic evaluation. Tissue sections from tooth pulp were immunoreacted with antibodies directed against CRF receptor 2 (CRF-R2) and neurofilament protein and examined to correlate CRF-R expression with pulpal diagnosis.

RESULTS

Our results indicated that symptomatic pulps demonstrated significantly greater expression of CRF-R2. The increased expression was localized on distinct cellular profiles throughout the pulp and was not directly correlated with neurofilament expression.

CONCLUSIONS

Our findings suggest that the analgesic effects of endogenously produced CRF may be enhanced via upregulation of CRF-R2 expression, and may explain the occurrence of reduced pain symptoms in some patients with irreversible pulpitis. The application of CRF-R agonists may be a feasible strategy in reducing pain associated with irreversible pulpitis.

Glial network responses to polymicrobial invasion of dentin

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.

Immunostaining of pulpal nerve fibre bundle/arteriole associations in ground serial sections of whole human teeth embedded in technovit® 9100

A technique for embedding human undecalcified tooth specimens in Technovit® 9100 was developed, which permits immunohistological evaluation of pulp tissue in serial ground sections. Human molars were divided into 14-18 sections of about 23 µm thickness. Immunohistological double staining for S-100 and CD34 revealed unique associations of myelinated nerve fibre bundles with arterioles, which continued through the entire tooth pulp. These arterioles were not only accompanied by, but partially or totally enveloped in longitudinally orientated myelinated nerve fibre bundles. We speculate that this unique arrangement may mechanically support the arterioles and alleviate detection or regulation of their contraction state by sensory nerve cells.