Quantitative evaluation of the immunocompetence of the dental pulp

Identification and Experimental Validation of LINC00582 Associated with B Cell Immune and Development of Pulpitis: Bioinformatics and In Vitro Analysis

BACKGROUND

Pulpitis is a common oral disease. Increasing evidence has demonstrated that long non-coding RNAs (lncRNAs) can regulate the immune response in pulpitis. This study focused on finding the key immune-related lncRNAs that regulate the development of pulpitis.

METHODS

Differentially expressed lncRNAs were analyzed. Enrichment analysis was performed to explore the function of differentially expressed genes. Immune cell infiltration was evaluated with Immune Cell Abundance Identifier. Cell Counting Kit-8 (CCK-8) and lactate dehydrogenase release assays were conducted to measure the viability of human dental pulp cells (HDPCs) and BALL-1 cells. Transwell assay was processed to prove migration and invasion of BALL-1 cells.

RESULTS

Our results revealed that 17 lncRNAs were significantly upregulated. Pulpitis-related genes were mainly enriched in inflammatory relative signal pathways. The abundance of various immune cells was significantly abnormal in pulpitis tissues, among which the expression of eight lncRNAs was significantly correlated with the expression of B cell marker protein CD79B. As the most relevant lncRNA for B cells, LINC00582 could regulate the proliferation, migration, invasion, and CD79B expression of BALL-1 cells.

CONCLUSIONS

Our study identified eight B cell immune-related lncRNAs. Meanwhile, LINC00582 has a positive effect on B cell immunity in the development of pulpitis.

Comparative Analysis of the Proteomic Profile of the Dental Pulp in Different Conditions. A Pilot Study

Abstract This study aimed to quantitatively compare the difference in protein expression in the progression of pulp pathogenesis, as well as to describe the biological functions of proteins identified in pulp tissue. Samples were obtained from six patients treated at the Araçatuba School of Dentistry and were divided into three groups: normal pulp - from teeth extracted for orthodontic indication; inflamed pulp and necrotic pulp - from patients diagnosed with irreversible pulpitis and chronic apical periodontitis, respectively. After previous proteomic preparation, dental pulp samples were processed for label-free quantitative proteomic analysis in a nanoACQUITY UPLC-Xevo QTof MS system. The difference in expression between the groups was calculated using the Protein Lynx Global Service software using the Monte Carlo algorithm. A total of 465 human proteins were identified in all groups. The most expressed proteins in the inflamed pulp group in relation to the normal pulp group were hemoglobin, peroxiredoxins and immunoglobulins, whereas the less expressed were the tubulins. Expression levels of albumins, immunoglobulins and alpha-2-macroglobulin were higher in the necrotic pulp group than in the inflamed pulp group. As for the qualitative analysis, the most prevalent protein functions in the normal pulp group were metabolic and energetic pathways; in the inflamed pulp group: cellular communication and signal transduction; and regulation and repair of DNA/RNA, while in the necrotic pulp group proteins were associated with the immune response. Thus, proteomic analysis showed quantitative and qualitative differences in protein expression in different types of pulp conditions.

Innate Immune Responses of the Dental Pulp to Caries

Various cells and inflammatory mediators are involved in the initial pulpal responses to caries. This review focuses on the cellular, neuronal, and vascular components of pulpal innate responses to caries. Discussion will include dentinal fluid, odontoblasts, neuropeptides, and neurogenic inflammation, which are not classic immune components but actively participate in the inflammatory response as the caries progress pulpally. Summaries of innate immune cells as well as their cytokines and chemokines in healthy and reversible pulpitis tissues are presented.

T lymphocyte subpopulations and interleukin-2, interferon-gamma, and interleukin-4 in rat pulpitis experimentally induced by specific bacteria

The objective of this study was to investigate the expression of surface markers on T lymphocytes and the Th1/Th2 immune response in pulpal inflammation associated with specific bacteria. Pulpal inflammation was experimentally induced in rat mandibular incisors by drilling, without coolant, to open pulp chambers. Streptococcus mutans (S. mutans group), Porphyromonas endodontalis (P. endodontalis group), and a sterile cotton pellet only (control group) were inoculated in the canal. The expression of CD25 and CD54 on CD4+, and CD8+ lymphocytes in pulp tissues was determined by using a flow cytometer. The levels of interleukin (IL)-2, interferon (IFN)-gamma, and IL-4 were measured by ELISA. Flow-cytometric analysis showed that the mean ratio of CD4+:CD8+ was 0.96 in the control group, 0.99 in the S. mutans group, and 0.52 in the P. endodontalis group. An increase in CD25 and CD54 expression on CD4+ T lymphocytes was related to the bacterial infection (p < 0.05) and accompanied an increase in IL-2 concentration. The higher concentration of IFN-gamma than IL-4 in the P. endodontalis group suggested a Th1 reaction in the early stage of pulpal inflammation induced by P. endodontalis.

Periapical inflammatory responses and their modulation

Periapical inflammatory responses occur as a consequence of bacterial infection of the dental pulp, as a result of caries, trauma, or iatrogenic insult. Periapical inflammation stimulates the formation of granulomas and cysts, with the destruction of bone. These inflammatory responses are complex and consist of diverse elements. Immediate-type responses--including vasodilatation, increased vascular permeability, and leukocyte extravasation--are mediated by endogenous mediators, including prostanoids, kinins, and neuropeptides. Non-specific immune responses--including polymorphonuclear leukocyte and monocyte migration and activation, and cytokine production--are elicited in response to bacteria and their products. Interleukin-1 and prostaglandins in particular have been implicated as central mediators of periapical bone resorption. Chronic periapical inflammation further involves specific T- and B-cell-mediated anti-bacterial responses, and activates a network of regulatory cytokines which are produced by Th1- and Th2-type T-lymphocytes. Various naturally occurring and genetically engineered models of immunodeficiency are beginning to help elucidate those components of the immune system which protect the pulpal/periapical complex. Both specific and non-specific responses interface with and are regulated by the neural system. The modulation of these responses by immune response modifies, cytokine antagonists, and other novel therapeutic agents is discussed. As an experimental model, periapical inflammation has many advantages which permit it to be used in studies of microbial ecology and pathogenesis, host response, neuroimmunology, and bone resorption and regeneration.

Immune defense mechanisms of the dental pulp

Defense reactions of the dentin/pulp complex involve a variety of biological systems, in which the immune system plays a pivotal role. The knowledge of the organization and function of pulpal immunocompetent cells has been sparse, but in recent years a significant body of information of immune mechanisms in general has provided a footing for substantial new knowledge of the immune mechanisms of the dental pulp. The identification of pulpal dendritic cells (DCs) has generated research activities which have led to a concept of how an antigenic challenge may evoke a pulpal inflammatory response. Although DCs are not able to identify foreign antigens specifically, they provide necessary signals to activate T-lymphocytes which in turn will orchestrate other immunocompetent cells to mount the local immune defense of the dental pulp. The purpose of this review is to accent the organization and function of pulpal DCs and other tissue and cellular components and to provide a basis for how they may interact to instigate pulpal defense mechanisms.

The effects of immunoglobulins on the convective permeability of human dentine in vitro

Immunoglobulin molecules are localized in the dentinal tubules of non-carious and carious teeth, but their possible role in caries invasion is not understood. This study sought to examine the effects of immunoglobulin molecules on dentine permeability using a fluid-filtration method. Crown segments cut from impacted human third molars were treated by filtration with 100 micrograms/ml IgG, 100 micrograms/ml IgA or 30 micrograms/ml IgM under a constant pressure. Flow rates were recorded and percent changes in flow rate analysed over time. Filtrates collected at various times were tested for changes in immunoglobulin concentrations by an enzyme-linked immunosorbent assay, and the percent retention of immunoglobulins to dentine was calculated. There was a decreasing non-linear exponential relation between the percent changes in flow rate and filtration time for all three immunoglobulins. The percentage of retained immunoglobulins was significantly related to the filtration time for all three classes of immunoglobulins. Immunoglobulin retention contributed to significant changes in flow rate with time. These in vitro results indicate the potential mechanism of immunoglobulins in decreasing tabular permeability.

Detection of human IL-2 in normal and inflamed dental pulps

Irreversible pulpitis has been associated with an increase in the number of pulpal T-cells. Interleukin-2 (IL-2) stimulates T-cell proliferation and signals the release of other proinflammatory mediators associated with connective tissue degradation. IL-2 has been suggested to be a useful marker of pathologic inflammatory activity in periodontal and systemic disease conditions. The purpose of this study was to analyze normal and inflamed dental pulps for the presence of immunoreactive IL-2 (iIL-2). Normal healthy pulpal tissue was obtained from 17 impacted third molars and inflamed samples were obtained from 12 symptomatic carious molars clinically diagnosed with irreversible pulpitis. Pulpal tissues were collected, prepared, and analyzed for histological status and iIL-2 concentration by a modified ELISA technique. iIL-2 was detected in all vital pulpal tissues. A t-test revealed significant differences in iIL-2 concentrations when inflamed pulpal tissues were compared to normal healthy samples (T = -2.75, p < 0.05). These results suggest that iIL-2 may serve as a marker of pathologic inflammatory activity in irreversible pulpitis.

Quantitative analysis of immunoglobulins and inflammatory factors in human pulpal blood from exposed pulps

The levels of immunoglobulins (IgG, IgA, and IgM) and inflammatory factors (elastase, prostaglandin E2, interleukin-1 alpha, interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha) in the blood of human dental pulp were quantified, using enzyme-linked immunosorbent assays. The pulpal blood samples were obtained with nylon fiber pellets from normal and inflamed dental pulp at pulp sites exposed on pulpectomy. Statistically significant differences between normal and inflamed pulp were found in the levels of IgG (p < 0.01), IgA (p < 0.05), IgM (p < 0.01), elastase (p < 0.05), and prostaglandin E2 (p < 0.01). These findings indicate that these factors play an important role in the pathogenesis of pulpal disease, and the sampling methods used in this study are useful for examination of pulpal inflammation.

Antibodies in normal and diseased pulps reactive with microorganisms isolated from deep caries

Immunoglobulin molecules in the supernatant fluids (SF) from pulpal explant cultures have been observed to react with microorganisms implicated in infections of root canals. In this study, the reactivity of immunoglobulin molecules in the SF from normal and irreversible pulpitis pulps to six strains of predominant microorganisms isolated from the immediate layer of carious lesions above the pulps used for explant cultures was investigated using an enzyme-linked immunosorbent assay. Two ATCC strains of Eubacterium were also included in this assay. Specific antibodies to Lactobacillus casei subsp. casei, Lactobacillus casei subsp. rhamnosus, Lactobacillus acidophilus (I), (II), Streptococcus mutans, Bacteroides intermedius, Eubacterium brachy, and Eubacterium alactolyticum in the SF from the normal and irreversible pulpitis tissues were observed with a large variation of antibody levels in both groups. Immunodiffusion assays of the SF revealed that IgG was the major class of immunoglobulin in the normal as well as the irreversible groups. The presence of natural antibodies in the normal pulps suggested a possible protective role of antibodies during the invasive process of caries.

Determination and relationship of C-reactive protein in human dental pulps and in serum

C-reactive protein (CRP), an acute phase protein synthesized by the liver, increases in serum as much as 3000 times above its normal level in response to acute inflammation. The purpose of this study was to determine whether CRP levels in dental pulps could be correlated with the histological disease status of the pulp and with systemic blood levels of CRP. Inflamed and necrotic pulps were extirpated during routine endodontic therapy. Normal pulps were removed from extracted, intact third molars. One half of each pulp specimen was placed in formalin for histological study; the other half was frozen for immunological study. A serum sample was obtained from each patient at the end of the dental visit. CRP levels were determined by the enzyme-linked immunosorbent assay. Pulps were categorized histologically as normal, inflamed, inflamed/necrotic, or necrotic. The correlation between CRP levels of pulp and serum was not significant. CRP levels of normal pulps differed significantly only from inflamed pulps (p less than 0.05, Dunnett). This increase in CRP appears to be a local phenomenon resulting from the interaction of CRP with various inflammatory mediators in the pulp.

Specificity of antibodies present in human periapical lesions

Various classes of immunoglobulins have been found in human periapical lesions. The specificity of secreted antibodies against antigens egressing from the root canal system has yet to be thoroughly investigated. The purpose of this study was to test the specificity of antibodies present in human periapical lesions. Human periapical biopsies were removed and cultured as organ culture explants. Antibodies present in the lesions were extracted in the cell culture fluids. A modified enzyme-linked immunosorbent assay was used to determine the presence, type, and concentration of different classes of antibodies against a number of commonly found bacterial species present in the root canal system. The data show the presence of specific antibodies (IgG, IgM, and IgA) against all 16 microorganisms tested. Peptostreptococcus micros, Actinomyces israelii, Staphylococcus intermedius, and Fusobacterium nucleatum produced significantly high levels of IgG antibodies in these lesions.

Identification of lymphocyte antigens in human dental pulps

The aim of the experiment was to study the immune reaction of cells in both healthy and inflamed human dental pulps. For this it was necessary to identify, in particular, populations of lymphocytes in the pulp, and also other cells involved in the immune reaction. By using monoclonal antibodies which specifically recognize subpopulations of the T lymphocytes, we were able: 1) to directly determine the phenotype of the cells of the pulp, 2) to examine the interactions of the different cell populations. The study was based on 30 permanent human dental pulps and the method was that of indirect immunofluorescence on frozen sections. The monoclonal antibodies used were the antibodies OKT and anti-Leu of types anti-Leu1, anti Leu3a, OKT4, OKT8 and OK1a. The results obtained were evaluated statistically. Two important points stand out from this study: 1) in the healthy samples there is preferential localization of lymphocytes at the periphery of the pulp and 2) there is a predominance of the OKT8+ cytotoxic suppressor subpopulation in both the healthy and the inflamed pulps.

A study of T and B cells in pulpal pathosis

A study was undertaken using monoclonal antibodies to determine the types of lymphocytes present in pulpal tissues. Pulps were extirpated from teeth clinically diagnosed as normal, reversibly inflamed, or irreversibly inflamed and stained with hematoxylin and eosin and an indirect immunoperoxidase technique using monoclonal antibodies reactive to pan-B lymphocytes (B), pan-T lymphocytes (T1), and helper (T4) and suppressor (T8) T lymphocytes. T and/or B lymphocytes were observed in normal pulpal tissues with T8 lymphocytes being predominant. The pulpal tissue in the reversible group demonstrated that more than 90% of the lymphocyte population were T lymphocytes, with a T4/T8 ratio of 0.56. Higher numbers of T1, T4, T8; and B lymphocytes were observed in the pulp from teeth in the irreversible group. A ratio of 1.14 of T4/T8 lymphocytes was observed in the irreversible group. A B/T1 lymphocyte ration of 1.60 suggested this ratio might be used as an index in the immunohistological diagnosis of irreversible pulpal pathosis. There appeared to be no association between the periodontal status of the teeth and the number of immunocompetent cells observed in the pulps. An hypothesis on the regulatory functions of T4 and T8 lymphocytes as well as the interaction of T and B lymphocytes and their products in the pathogenesis of pulpal disease is presented.

Identification of bacteria in immunopathologic mechanisms of human dental pulp

Serial frozen sections from human dental pulp were used for the identification of oral bacteria in immunopathologic mechanisms. Sera raised against Actinomyces viscosus, A. naeslundii, Bacteroides gingivalis, and B. melaninogenicus ss. intermedius, commercial sera against human immunoglobulins, complement, and monoclonal antibodies against human T cells were used in a double-staining immunofluorescence technique. Sections of dental pulp from normal teeth showed no penetration of bacteria or bacterial antigens and no signs of inflammation. A unique aspect of the present study was the demonstration that penetrating bacteria and bacterial antigens in the pulp of involved teeth were always associated with antibodies and frequently also with complement. A. viscosus has been found most frequently in complement-fixing immune complexes followed by B. gingivalis. A. naeslundii and B. melaninogenicus ss. intermedius were found only in complexes with antibodies. The involvement of plasma cells and T cells was also demonstrated. In the dental pulps of diseased teeth, cytotoxic and Arthus type immunopathologic reactions occurred.

Humoral antibodies to anaerobic bacteria isolated from patients with pulpal-periapical disease

The purpose of this investigation was to determine if anaerobic bacteria isolated from pulpal-periapical infections elicit a humoral immune response in the host. Results indicated that patients with pulp and periapical disease do not have significantly raised levels of IgG or IgM in their serum and that in the acute sera the precipitin antibody titer to the anaerobic bacteria was significantly higher in the patient group than in the control group. However, there was no significant difference in antibody titer for the convalescent sera in the patient and control groups or the acute and convalescent sera for the patient group.