Immunoregulatory effects of dental mesenchymal stem cells on T and B lymphocyte responses in primary Sjögren's syndrome.

Background: In this article, the authors investigate the modulatory effects of dental mesenchymal stem cells (MSCs) on lymphocyte responses in primary Sjögren's syndrome (pSS), which is an autoimmune disease resulting from keratoconjunctivitis sicca and xerostomia. Methods: Mononuclear cells isolated from pSS patients cultured with or without dental MSCs and analyzed for lymphocyte responses via flow cytometry. Results: Dental-follicle (DF)- and dental-pulp (DP)-MSCs downregulated CD4+ T lymphocyte proliferation by increasing Fas-ligand expression on T lymphocytes and FoxP3 expressing Tregs, and decreasing intracellular IFN-γ and IL-17 secretion in pSS patients. DF-MSCs decreased the plasma B cell ratio in the favor of naive B cell population in pSS patients' mononuclear cells. Conclusion: DF- and DP-MSCs can be the new cellular therapeutic candidates for the regulation of immune responses in pSS.

Plain language summary In this article, the authors investigate the modulatory effects of dental mesenchymal stem cells (dental MSCs) on lymphocyte responses in primary Sjögren's syndrome (pSS), which is characterized by the infiltration of lymphocytes in exocrine glands. Lymphocyte proliferation, apoptosis, Tregs and total Bregs, intracellular cytokine secretion, total memory, plasma and naive B cell subsets were analyzed in pSS patients and compared them with healthy individuals. Dental follicle- and dental pulp-MSCs modulated CD4⁺ T lymphocyte responses in pSS patients' mononuclear cells by increasing Fas-ligand expression, enhancing FoxP3-expressing Tregs, and decreasing pro-inflammatory cytokine secretion. Our findings provide evidence for the potential role of dental-MSCs as a cellular therapy option in the treatment of pSS.

3D Visualization of Dynamic Cellular Reaction of Pulpal CD11c+ Dendritic Cells against Pulpitis in Whole Murine Tooth.

In dental pulp, diverse types of cells mediate the dental pulp immunity in a highly complex and dynamic manner. Yet, 3D spatiotemporal changes of various pulpal immune cells dynamically reacting against foreign pathogens during immune response have not been well characterized. It is partly due to the technical difficulty in detailed 3D comprehensive cellular-level observation of dental pulp in whole intact tooth beyond the conventional histological analysis using thin tooth slices. In this work, we validated the optical clearing technique based on modified Murray's clear as a valuable tool for a comprehensive cellular-level analysis of dental pulp. Utilizing the optical clearing, we successfully achieved a 3D visualization of CD11c+ dendritic cells in the dentin-pulp complex of a whole intact murine tooth. Notably, a small population of unique CD11c+ dendritic cells extending long cytoplasmic processes into the dentinal tubule while located at the dentin-pulp interface like odontoblasts were clearly visualized. 3D visualization of whole murine tooth enabled a reliable observation of these rarely existing cells with a total number less than a couple of tens in one tooth. These CD11c+ dendritic cells with processes in the dentinal tubule were significantly increased in the dental pulpitis model induced by mechanical and chemical irritation. Additionally, the 3D visualization revealed a distinct spatial 3D arrangement of pulpal CD11c+ cells in the pulp into a front-line barrier-like formation in the pulp within 12 h after the irritation. Collectively, these observations demonstrated the unique capability of optical clearing-based comprehensive 3D cellular-level visualization of the whole tooth as an efficient method to analyze 3D spatiotemporal changes of various pulpal cells in normal and pathological conditions.

Nexus between COVID-19 and periodontal disease.

Over the past several decades, studies have demonstrated the existence of bi-directional relationships between periodontal disease and systemic conditions. Periodontitis is a polymicrobial and multifactorial disease involving both host and environmental factors. Tissue destruction is primarily associated with hyperresponsiveness of the host resulting in release of inflammatory mediators. Pro-inflammatory cytokines play a major role in bacterial stimulation and tissue destruction. In addition, these cytokines are thought to underlie the associations between periodontitis and systemic conditions. Current research suggests that increased release of cytokines from host cells, referred to as the cytokine storm, is associated with disease progression in patients with coronavirus disease 2019 (COVID-19). An intersection between periodontitis and pulmonary disease is biologically plausible. Hence, we reviewed the evidence linking COVID-19, cytokines, and periodontal disease. Plaque control is essential to prevent exchange of bacteria between the mouth and the lungs, reducing the risk of lung disease. Understanding these associations may help identify individuals at high risk and deliver appropriate care at early stages.

Th17 Cytokines and its Correlation with Receptor Activator of Nuclear Factor kappa B Ligand During Orthodontic Tooth Movement.

BACKGROUND: IL-17 is reported to be associated with the pathophysiology of Orthodontic Tooth Movement (OTM) by affecting osteoclastogenesis. OBJECTIVE: To explore the changes of Th17 cytokines (IL-17, IL-23, and IL-27) expression and its correlation with receptor activator of nuclear factor kappa B ligand (RANKL) during orthodontic tooth movement. METHODS: Thirty patients who needed extraction of the first premolar during orthodontic treatment were included. The gingival crevicular fluid was sampled at the day of application (T0), one hour (T1), 24 hours (T2), one week (T3), four weeks (T4), and 12 weeks (T5) after the application of orthodontic force. The expression of Th17 cytokines and RANKL were measured by using enzyme-linked immunosorbent assay and, their correlations were assessed. RESULTS: The levels of IL-17A, IL-17F, IL-23, and IL-27 at both tension and pressure sides of studied teeth at T2-T4 were significantly higher compared with that of T0 and T1. Moreover, the expression of IL-27 at both tension and pressure sides of studied teeth at T2-T4 was significantly lower compared with that of T0 and T1. At T5, IL-17A, IL-17F, IL-23, and IL-27 returned to the baseline level. For the control group, the cytokines were not significantly different at various time points. The expression of IL-17A, IL-17F, and IL-23 was positively correlated with RANKL expression at T2-T4, whereas the IL-27 was negatively correlated with RANKL expression at T2-T4. CONCLUSION: This study provided preliminary evidence that Th17 cytokines may be involved in the regulation of OTM.

Immunological profile of teeth with inflammatory periapical disease from chronic liver disease patients.

AIM: To evaluate the mRNA expression levels of the cytokines interferon-γ, tumour necrosis factor-α, interleukin (IL)-1ß, IL-10, IL-6, VEGF, and AGT and the chemokine CCL2/MCP-1 in periapical interstitial fluid associated with root canal infections before and after the reduction of the bacterial load using a cleaning procedure. METHODOLOGY: The case group included 11 patients with chronic liver disease, and the control group included 11 healthy patients. Clinical samples were taken from teeth with pulp necrosis. After cleaning and drying the canal, three paper points were introduced into the root canal and passed through the root apex (2 mm) into the periapical tissues for 1 min. The samples were collected immediately after root canal cleaning and 7 days later to characterize those gene expression levels using real-time PCR. The data were subjected to the Shapiro-Wilk and the Wilcoxon tests. RESULTS: In the control group, significantly increased expression of the pro-inflammatory cytokines IFN-γ and TNF-α was observed in teeth with restrained bacterial loads (day 7) (P < 0.05). Similarly, increased TNF-α expression was found on day 7 in the liver group (P < 0.05). No differences were observed in the expression levels of the IL-1ß, IL-10 and, IL-6, MCP-1/CCL-2 and VEGF between the first collection (day 0) and second collection (day 7), over time in either group. CONCLUSION: Chronic liver disease patients exhibited sufficient immunologic ability showing relatively similar expression levels of cytokines, chemokines and angiogenic factors in periapical samples compared with the responses from no-chronic liver disease patients. The outcomes of this study suggest that liver impairment did not compromise the periapical immune response.

SOME CHARACTERISTICS OF THE ORAL CAVITY AND TEETH OF COSMONAUTS ON MISSIONS TO THE INTERNATIONAL SPACE STATION.

Earlier studies were furthered by examination of parodentium anaerobic microbiota and investigation of gingival liquid immunological factors in space flight. Immunoglobulins were measured using the .enzyme immunoassay (EM). The qualitative content of keya parodentium pathogens is determined with state-of-the-art molecular biology technologies such as the polymerase chain reaction. Statistical data processing was performed using the principle component analysis and ensuing standard statistical analysis. Thereupon, recommendations on cosmonaut's oral and dental hygiene during space mission were developed.

Manual versus sonic-powered toothbrushing for plaque reduction in patients with dental implants: an explanatory randomised controlled trial.

PURPOSE: The aim of the present study was to investigate plaque levels following sonic-powered and manual toothbrushing in subjects with dental implants. MATERIALS AND METHODS: This study included 36 male and 47 female partially edentulous patients (age range 45-78 years, mean age 59.8 years) that were randomly assigned to one of two treatment groups: the sonic toothbrush group (n = 42; Philips Sonicare FlexCare® toothbrush) or the manual toothbrush group (n = 41; Oral-B P40®). Clinical, microbiological and immunological examinations were performed blinded at baseline and after 3, 6, 9 and 12 months. Microbiological analyses were performed by real-time polymerase chain reaction. Immunological analyses (prostaglandin E2) were performed by chromatography-electrospray spectrometry. RESULTS: The plaque index difference between baseline and 12 months at implants showed no significant difference between sonic or manual toothbrushing in a two-sided Mann-Whitney test (W = 773.5, P = 0.426, 95% CI -0.64 to 0.20). At the end of the study, there were no significant changes in plaque index, bleeding on probing, gingival index, pocket probing depth, gingival recession, clinical attachment level or the microbiological and immunological outcomes at implants or teeth in either group. CONCLUSIONS: This study uncovered no significant difference between sonic and manual toothbrushing for plaque reduction at implants and teeth. Both toothbrushes maintain healthy peri-implant soft tissue.

The impact of chlorhexidine-based endodontic treatment on periapical cytokine expression in teeth.

INTRODUCTION: Root canal treatment typically involves cleaning and shaping procedures followed by treatment with antibacterial endodontic dressing between appointments and, ultimately, 3-dimensional,hermetic filling. Chlorhexidine (CHX) is effective as an irrigation solution and is used as an endodontic dressing. The aim of this study was to examine the influence of CHX on periapical cytokine expression. METHODS: Expression levels of the cytokines interferon γ, tumor necrosis factor α, interleukin (IL)-1ß, IL-17A, IL-10, and the chemokine monocyte chemoattractant protein-1 (CCL2/MCP-1) were assayed by real-time polymerase chain reaction immediately after root canal cleaning and 15 days later. RESULTS: Messenger RNA expression of IL-1ß, interferon γ, IL-10, and CCL2/MCP-1 was increased on day 15 in teeth without endodontic dressing. No statistical change was observed in the messenger RNA expression of cytokines when comparing sampling times for teeth that received endodontic dressing. CONCLUSIONS: The results show that CHX application between appointments prevented the increase of both proinflammatory and immunoregulatory cytokines 15 days after the dental procedure.

Caries induced cytokine network in the odontoblast layer of human teeth.

BACKGROUND: Immunologic responses of the tooth to caries begin with odontoblasts recognizing carious bacteria. Inflammatory propagation eventually leads to tooth pulp necrosis and danger to health. The present study aims to determine cytokine gene expression profiles generated within human teeth in response to dental caries in vivo and to build a mechanistic model of these responses and the downstream signaling network. RESULTS: We demonstrate profound differential up-regulation of inflammatory genes in the odontoblast layer (ODL) in human teeth with caries in vivo, while the pulp remains largely unchanged. Interleukins, chemokines, and all tested receptors thereof were differentially up-regulated in ODL of carious teeth, well over one hundred-fold for 35 of 84 genes. By interrogating reconstructed protein interaction networks corresponding to the differentially up-regulated genes, we develop the hypothesis that pro-inflammatory cytokines highly expressed in ODL of carious teeth, IL-1ß, IL-1α, and TNF-α, carry the converged inflammatory signal. We show that IL1ß amplifies antimicrobial peptide production in odontoblasts in vitro 100-fold more than lipopolysaccharide, in a manner matching subsequent in vivo measurements. CONCLUSIONS: Our data suggest that ODL amplifies bacterial signals dramatically by self-feedback cytokine-chemokine signal-receptor cycling, and signal convergence through IL1R1 and possibly others, to increase defensive capacity including antimicrobial peptide production to protect the tooth and contain the battle against carious bacteria within the dentin.

Improved methods for immunohistochemical detection of BrdU in hard tissue.

Bromodeoxyuridine (BrdU) is used to label synthesizing DNA and to chase label-retaining cell (LRC). As stem cells divide slowly in adult tissues, they can be visualized as LRCs. In order to identify LRCs in hard tissue, we examined optimal conditions of fixation, demineralization, and DNA denaturation/antigen retrieval for immunohistochemistry of BrdU in hard tissues including bone, tooth, and periodontal ligament. Mice were subcutaneously injected with BrdU (50 microg/g body weight) twice a day from the postnatal day 11 to day 15 and sacrificed at 2 h after the last injection. Dissected maxillae were fixed (Bouin's solution or 4% paraformaldehyde), demineralized (Morse's solution or EDTA), and embedded in paraffin. Antigen retrieval procedures were performed before incubation with primary antibody. When sections were treated with HCl for DNA denaturation, the staining intensity of BrdU positive cells was not affected by difference of fixatives. Higher sensitivity was obtained by demineralization with Morse than with EDTA. Although heat-induced antigen retrieval techniques in citrate buffer (pH 6.0) showed as well or better sensitivity than acid pretreatment, heating caused tissue damage specifically to tooth dentine and the surrounding tissue. When the LRCs at four weeks after the last injection of BrdU were compared, much more LRCs were observed in specimen demineralized with Morse than with 10% EDTA. Our data suggest that demineralization with Morse with Bouin fixative plus HCl pretreatment gives rise to the optimal results for BrdU immunodetection in hard tissue.

[Detection of ABO and GM system antigens in the teeth]. / Vyiavlenie antigenov sistem ABO i GM v zubakh.

A series of experiments using agglutination inhibition reaction and material extraction in PBS with pH 7.2 (phosphate-buffer-sedin) has been made to detect antigens of the GM system in the teeth. Parameters of the test material/serum ratio are proposed. In parallel, control specimens of blood were examined. The results of the experiments suggest that detection of Gm antigens in the teeth is feasible. In some cases this may raise an identification level of the expert conclusions. The above technique can be used for investigation of the bones.

[The change of immunocompetent cells in normal human dental pulp during development of immature permanent teeth].

OBJECTIVE: To study changes of several immunocompetent cells (ICCs), namely, pulpal dendritic cells (PDCs), T lymphocytes, B lymphocytes, and endothelial cells, in normal human dental pulp according to different development stage of completely erupted but not fully developed premolar in order to provide evidence for local immune defense mechanisms during development of immature permanent teeth. METHODS: Based on the dental development status, the pulp tissue was classified into the following groups: big trumped-shaped group, small trumped-shaped group and closed group. The above mentioned cells were immunohistochemically examined by use of HLA-DR, CD45RO, CD20 mouse anti-human monoclonal antibodies. Double-staining was also done by use of the former two antibodies. The number of positively stained cells or blood vessels was counted and statistically analyzed. RESULTS: 1. Normal dental tissue of three groups all expressed HLA-DR+ PDCs. Among three groups, the number of HLA-DR+ cells in big trumped-shaped group was more than that of small trumped-shaped group and closed group. 2. There was no significant difference of positive blood vessel rate of HLA-DR expressing endothelial cells among three groups. 3. There was no significant difference of CD45RO+ T cells among three groups. 4. By use of double-labeling immunohistochemistry, HLA-DR+ PDCs and CD45RO+ T cells were found to be rarely in contact with each other. Correlation analysis between two kinds of cells did not indicate the linear relationship. CONCLUSIONS: The number of PDCs tends to decrease with increasing age in the developing dental pulp of human normal tooth, other ICCs are not related with dental development.

[Dental status of children whose parents are engaged in polyurethane foam manufacture]. / Stomatologicheskii status detei rabochikh proizvodstva penopoliuretanov.

Children of workers engaged in polyurethane foam industry have high occurrence of cariosity and noncarious teeth affections, alteration of the mineral saliva composition, subnormal general and local immunity.

[The local immune mechanisms of the involvement of the teeth and periodontium in periodic disease]. / O mestnykh immunnykh mekhanizmakh porazheniia zubov i parodonta pri periodicheskoi bolezni.

The aim of our investigations was to elucidate some immune aspects of combination of caries and periodontitis with periodic disease (PD), also known as familial Mediterranean fever. In this regard in patients with active and non-active stage of PD we have studied dynamic changes of concentration of secretory immunoglobulin A (SIgA) in saliva and phagocytic activity of neutrophils derived from gum blood. It has been shown that in patients with PD these indices of local immunity of oral cavity had tendency to a decrease especially in case of PD and periodontitis combination. Disturbances of local immunity was significant in active stage of PD. Based on the obtained data and analysis of latest literature data we suppose that above mentioned changes in local immunity depended on the exhaustion of adaptive properties of patients' local immunity more pronounced in case of chronic inflammation and infection foci formation in oral cavity.

[The immunogenicity of tooth allografts in mice].

The mice used in this study were of the in-bred strains C57BL/6 and Balb/c which differ at the major histocompatibility complex (MHC). The immunogenicity of tooth allografts was studied in vitro by means of detecting the response of Antibody-Complement Mediated Cytotoxity (ACMC) and Cell Mediated Cytotoxity (CMC) of the host. We found that there was significant difference for both ACMC and CMC activity between the allogenic and isogenic tooth transplantation (P < 0.01). The results indicate that tooth allografts are immunogens and do evoke the immune response of recipients.

Immunohistochemical staining of human teeth, and production of monoclonal antibodies against cementum.

Influence of various forms of fixation and decalcification on immunohistochemical staining of paraffin-embedded human teeth and surrounding tissues was initially examined using commercially available antibodies against vimentin (V), type I collagen (C) and cytokeratin (K). Secondly, monoclonal antibody (MoAb) was produced against both bovine and human cementum and immunohistochemical screening was subsequently undertaken to test reactivity with different scheme of fixation and decalcification. The combination of neutral buffered paraformaldehyde fixation, Morse solution and unmasking procedure yielded both optimal morphology and immunoreactivity. The application of this method into production of MoAb against human or bovine cementum generated a variety of MoAbs reactive with both human teeth and surrounding tissues. The percentage of hybridoma supernatant reactive with sections of human teeth was 14.0-22.4% and was both higher and much improved compared to results of previous soft tissue studies. Finally, the MoAbs, BC 1 and 2 (isolated following the use of bovine cementum as immunogen) and HC 1 (human cementum immunogen) recognized specific bands of various molecular weight. The three MoAbs showed strong resistance against periodate oxidation and borohydrate reduction and were stable following treatment with proteolytic enzymes. All were immunoreactive with components of cementum.

[The detection of ABO system antigens in bone, nail and tooth fragments]. / Vyiavlenie antigenov sistemy ABO v fragmentakh kostei, nogtei i zubov.

Fragments of the bones, nails, and teeth were examined in 12 forensic biological departments of bureaus for forensic medical expert evaluation of the Russian Federation. A total of 790 experiments were carried out with 145 bones, 5 teeth, and nails from 12 cadavers. In the overwhelming majority of cases the experiments were carried out with control investigations of blood, hair, salivary, and sweat samples. Modifications of the absorption-elution method were used to detect the AB0 antigens, these modifications involving all stages of the test (fixation, fat extraction, medium for elution, reagents, time factors in absorption and elution, etc.). Analysis of the data permitted the authors to make some conclusions and offer recommendations for practical biological experts.

Parvalbumin- and calretinin-immunoreactive trigeminal neurons innervating the rat molar tooth pulp.

Calcium-binding proteins and neuropeptides were examined in trigeminal neuronal cell bodies retrogradely labeled with Fast blue (FB) from the maxillary molar tooth pulp of the rat. FB-labeled cells were located in the maxillary division of the trigeminal ganglion. Approximately 30 and 50% of the labeled cells were immunoreactive for parvalbumin and calcitonin gene-related peptide (CGRP), respectively. The coexpression of these substances was observed in 9.5% of FB-labeled cells. On the other hand, 2.4% of FB-labeled cells exhibited calretinin-immunoreactivity (CR-ir) and 20% tachykinin (TK)-ir. The coexpression of CR and TK was observed in 1.9% of FB-labeled cells, i.e., most of CR-ir FB-labeled neurons coexpressed TK-ir. An immuno-EM method revealed that all parvalbumin-ir nerve fibers in the root pulp were myelinated and that CGRP-ir nerve fibers were both myelinated (15%) and unmyelinated (85%). The present study indicated that primary nociceptors innervating the rat molar tooth pulp contained parvalbumin and CR and coexpressed these calcium-binding proteins and neuropeptides. It was suggested that peripheral axons of parvalbumin-ir tooth pulp primary neurons are all myelinated. Most peripheral CR-ir axons are probably unmyelinated because TK-ir myelinated axons have never been demonstrated in any peripheral organ.

ABO blood grouping on dental tissue.

Twenty-five permanent teeth, including eight carious ones whose pulp cavities had been exposed, were used for this research 3-5 weeks after extraction. Phosphate-buffered saline (PBS, at pH 7.2) was employed to extract ABO blood group substance from tooth powder. ABO grouping was performed on blood-stained compresses from the extraction wound (as controls), tooth fragment, tooth powder, and cotton fibers immersed in PBS extract by absorption-elution (AE) technique and on the PBS extracts by the two-dimensional absorption-inhibition (2-D AI) technique. It was found that blood grouping in PBS extracts by 2-D AI yielded reliable results: no false positive results, and a high rate of correct grouping, (24/25), while blood grouping on other dental materials, such as tooth fragments, tooth powders, immersed fibers, by AE gave an unacceptable rate of false positive/negative results.

An investigation into the mechanism of protection by local passive immunization with monoclonal antibodies against Streptococcus mutans.

Local oral passive immunization with Streptococcus mutans-specific monoclonal antibody (MAb) (Guy's 13) prevented recolonization by indigenous S. mutans in human volunteers who had first been treated with a conventional antibacterial agent (chlorhexidine). The F(ab')2 fragment of the MAb was as protective as the intact immunoglobulin G, but the Fab fragment of the molecule failed to prevent recolonization of S. mutans. In subjects receiving the MAb Fab fragment, S. mutans levels in dental plaque and saliva reappeared at a similar rate to that found in sham-immunized subjects who received either saline or a nonprotective MAb. In vitro, MAb had no bacteriostatic or bacteriocidal effect on S. mutans. However, S. mutans grown in the presence of either intact immunoglobulin G MAb or the F(ab')2 fragment formed very long chains, which resulted in clumping of the cells. S. mutans grown with either saline or the MAb Fab fragment formed significantly shorter chains, more characteristic of streptococcal growth in liquid media. The results suggest that the two binding sites of the MAb molecule may be an essential feature for preventing streptococcal colonization but that the ability to bind to phagocytes and activate complement which resides in the Fc fragment is not essential. Protection against colonization by S. mutans lasting up to 2 years was observed in immunized subjects, although MAb was applied over a period of only 3 weeks. Furthermore, functional MAb was detected up to 3 days following application of MAb to the teeth. The long-term protection could not be accounted for by a persistence of MAb on the tooth surface, and we have suggested that it may be due to a shift in the balance of the oral flora which discouraged recolonization by S. mutans. However, examination of the proportions of Streptococcus sanguis and veillonella species in the recolonization experiments failed to reveal a significant change in the proportions of either organism, which returned to approximately the preexperimental levels in both the immunized and control groups. These findings confirm the in vivo functional specificity of the MAb to S. mutans but are not consistent with the suggestion that S. sanguis or veillonella take over the niche vacated by S. mutans, unless the shift in the proportion of these organisms cannot be detected by the method used.