Mast cells and lymphocyte subsets in pulps from healthy and carious human teeth

Comparative Metabolomics Reveals the Microenvironment of Common T-Helper Cells and Differential Immune Cells Linked to Unique Periapical Lesions

Periapical abscesses, radicular cysts, and periapical granulomas are the most frequently identified pathological lesions in the alveolar bone. While little is known about the initiation and progression of these conditions, the metabolic environment and the related immunological behaviors were examined for the first time to model the development of each pathological condition. Metabolites were extracted from each lesion and profiled using gas chromatography-mass spectrometry in comparison with healthy pulp tissue. The metabolites were clustered and linked to their related immune cell fractions. Clusters I and J in the periapical abscess upregulated the expression of MMP-9, IL-8, CYP4F3, and VEGF, while clusters L and M were related to lipophagy and apoptosis in radicular cyst, and cluster P in periapical granuloma, which contains L-(+)-lactic acid and ethylene glycol, was related to granuloma formation. Oleic acid, 17-octadecynoic acid, 1-nonadecene, and L-(+)-lactic acid were significantly the highest unique metabolites in healthy pulp tissue, periapical abscess, radicular cyst, and periapical granuloma, respectively. The correlated enriched metabolic pathways were identified, and the related active genes were predicted. Glutamatergic synapse (16–20),-hydroxyeicosatetraenoic acids, lipophagy, and retinoid X receptor coupled with vitamin D receptor were the most significantly enriched pathways in healthy control, abscess, cyst, and granuloma, respectively. Compared with the healthy control, significant upregulation in the gene expression of CYP4F3, VEGF, IL-8, TLR2 (P < 0.0001), and MMP-9 (P < 0.001) was found in the abscesses. While IL-12A was significantly upregulated in cysts (P < 0.01), IL-17A represents the highest significantly upregulated gene in granulomas (P < 0.0001). From the predicted active genes, CIBERSORT suggested the presence of natural killer cells, dendritic cells, pro-inflammatory M1 macrophages, and anti-inflammatory M2 macrophages in different proportions. In addition, the single nucleotide polymorphisms related to IL-10, IL-12A, and IL-17D genes were shown to be associated with periapical lesions and other oral lesions. Collectively, the unique metabolism and related immune response shape up an environment that initiates and maintains the existence and progression of these oral lesions, suggesting an important role in diagnosis and effective targeted therapy.

Immunohistochemical quantification of mast cells in inflamed and noninflamed pulp tissue

Background

Dental pulp inflammation is a very complex process due to its situation in low compliance (confined environment) surrounded by mineralized dentin. Mast cells are one of the mediators of inflammation. Immunohistochemical localization of mast cells by anti-tryptase antibodies in formalin-fixed paraffin-embedded sections has been shown to be highly specific. The aim of the present study is to quantify the mast cells in inflamed and noninflamed human pulp tissue using immunohistochemical analysis.

Materials and Methods

Immunohistochemical localization of mast cells by anti-tryptase antibody was done in 15 inflamed and 15 noninflamed formalin-fixed paraffin-embedded pulp tissue. A number of mast cell per five high-power fields were performed using three observers and the mean was calculated. Statistical analysis was performed using t-test.

Results

The results of the present study showed an increased number of mast cells in inflamed pulp in comparison with noninflamed pulp.

Conclusion

Thus, the presence of mast cells in pulp inflammation could be used as a diagnostic marker. It can also aid in the management of pulpitis as mast cell stabilizers and antihistaminic agents could be used to control pulpal pain and inflammation.

Inflammatory response of human dental pulp to at-home and in-office tooth bleaching

Tooth bleaching is a technique of choice to obtain a harmonious smile, but bleaching agents may damage the dental pulp.

Phenotypic analysis of immunocompetent cells in healthy human dental pulp

INTRODUCTION

Like other tissues in the body, the human dental pulp is equipped with a network of immune cells that can be mobilized against pathogens when they invade the tooth. Very little data, mostly obtained with classic histologic methods, have reported their quantities and relative percentages. The objective of this study was to characterize and precisely quantify immunocompetent cells in healthy human dental pulp by using fluorescence-activated cell sorting, together with identifying specific cell subsets in the leukocyte (CD45(+)) cells.

METHODS

Healthy human third molars were collected from 42 young patients. Dental pulps were separated from the hard tissues and prepared for flow cytometry or immunostaining analyses.

RESULTS

CD45(+) cells represented 0.94% ± 0.65% of cells obtained from the enzymatic digestion of whole dental pulps (n = 34). CD16(+)CD14(+) granulocytes/neutrophils (50.01% ± 9.08%, n = 7) were found to represent the major subpopulation in CD45(+) cells followed by CD3(+) T lymphocytes (32.58% ± 11%, n = 17), CD14(+) monocytes (8.93% ± 5.8%, n = 7), and HLA-DR(high) Lin1(-) dendritic cells (4.51% ± 1.12%, n = 7). Minor subpopulations included CD3(-)CD56(+) natural killer cells (2.63% ± 1.15%, n = 7) and CD19(+) B lymphocytes (1.65% ± 0.89%, n = 17). We further identified cells harboring a phenotype compatible with Foxp3/CD25-expressing regulatory T lymphocytes (CD45(+)CD3(+)CD4(+)CD127(low)). Fluorescence-activated cell sorting analysis and confocal microscopy also revealed expression of HO-1 in HLA-DR(+) cells.

CONCLUSIONS

For the first time, this study identifies and precisely quantifies the relative proportion of immunocompetent cells potentially involved in tissue homeostasis of healthy human dental pulp.

Immunolocalization of dentin matrix protein-1 in human primary teeth treated with different pulp capping materials

The aim of this study was to evaluate the immunolocalization of dentin matrix protein (DMP)-1 in human primary teeth treated with different pulp capping materials. Twenty-five primary molars were divided into the following groups: formocresol (FC), calcium hydroxide (CH), mineral trioxide aggregate (MTA), corticosteroid/antibiotic solution + CH (O + CH), and Portland cement (PC), and all received conventional pulpotomy treatment. The teeth at the regular exfoliation period were extracted for histological analysis and immunolocalization of DMP-1. Statistical analysis was performed using the χ(2) test (p < 0.05). Histological analysis revealed statistically significant differences in the comparison among the groups through the use of a score system regarding the presence of hard tissue barrier, odontoblastic layer, and internal resorption, but not regarding pulp calcification. Immunohistochemical analysis showed immunostaining for DMP-1 in groups CH, MTA, O + CH, and PC. Internal resorption was observed in the groups FC and CH. MTA and PC showed pulp repair without inflammation and with the presence of hard tissue barrier. DMP-1 immunostaining was higher for MTA and PC, confirming the reparative and bioinductive capacity of these materials.

Characterization of inflammatory cell infiltrate in human dental pulpitis

INTRODUCTION

To evaluate the microscopic characteristics and densities (per mm(2) ) of tryptase(+) mast cells, CD4(+) T helper lymphocytes, CD45RO(+) memory T lymphocytes, foxp3(+) T regulatory lymphocytes, CD20(+) B lymphocytes, CD68(+) macrophages, and CD31(+) blood vessels in human dental pulpitis (n=38) and healthy pulpal tissue (n=6).

METHODOLOGY

The pulps of 38 human teeth with a clinical diagnosis of irreversible pulpitis were removed by pulpectomy. The pulp tissue was immersed in 10% buffered formalin for evaluation using light microscopy. Tryptase, CD4, CD45RO, foxp3, CD20, CD68, and CD31 expressions were analysed using immunohistochemistry; other microscopic features, such as intensity of inflammatory infiltrate and collagen deposition, were evaluated using haematoxylin and eosin stain. Wilcoxon and Mann-Whitney tests were used for statistical analysis. The significance level was set at α=5%.

RESULTS

Two microscopic patterns of pulpitis were found: group 1 (G1) (n=15) had an intense inflammatory infiltrate and mild collagen deposition; conversely, group 2 (G2) (n=23) had a scarce inflammatory infiltrate and intense collagen deposition. The numbers of CD68(+) macrophages (P=0.004) and CD20(+) B (P=0.068) lymphocytes and the density of blood vessels (P=0.002) were higher in G1 than in G2. However, a similar number of CD4(+) and CD45RO(+) T lymphocytes was found in both groups (P>0.05). When present, tryptase(+) mast cells were equally distributed in G1 and G2, whereas foxp3(+) T regulatory lymphocytes were detected in 59% and 14% of the samples of G1 and G2. Controls exhibited lower numbers of foxp3, tryptase, CD4, CD45RO, CD68 and CD20 positive cells than G1 and G2.

CONCLUSIONS

Irreversible pulpitis had distinct microscopic features with important quantitative and qualitative differences in inflammatory cell infiltration.

The relationship of pulp polyp with the presence and concentration of immunoglobulin E, histamine, interleukin-4 and interleukin-12

The aim of this study was to evaluate the relationship between pulp polyp formation and immunoglobulin E (IgE), histamine and interleukin-4 (IL-4) as the most important mediators which are involved in allergy. Thirty-two samples including 16 pulp polyps and 16 normal pulps were gathered. After homogenising the pulpal tissue samples, enzyme-linked immunosorbent assay (ELISA) techniques were used to assess the concentration of IgE, histamine, IL-4 and IL-12. The two groups showed statistically significant differences in terms of both the concentration and presence of IgE, histamine and IL-4 (P < 0.001); both presence and concentration of IgE, histamine and IL-4 were higher in pulp polyps than in normal pulps. There is not any significant difference between case and control groups regarding IL-12. The results of this study give rise to the possibility of type I hypersensitivity reaction being involved in pulp polyp's pathogenesis.