Production of interleukin-8 in vitro by mononuclear cells isolated from human periapical lesions

INTRODUCTION: Interleukin-8 (IL-8) is an important mediator of inflammation. However, little is known about its production in chronic dental periapical lesions and this was the main aim of this work. METHODS: Inflammatory cells were isolated from clinically different periapical lesions and analyzed by morphological criteria. The mononuclear cells were isolated, phenotypically analyzed by immunocytochemistry and cultivated in vitro. IL-8 was measured in culture supernatants of these periapical lesion mononuclear cells (PL-MNC) using a microbeads fluorescence assay. RESULTS: We found a relatively high production of IL-8 in 19 out of 21 periapical lesions included in the study. The level of IL-8 and the proportion of neutrophil granulocytes were significantly higher in the group of symptomatic lesions, compared to the asymptomatic lesions, but there was no statistically significant correlation between these parameters. According to the predominance of CD3(+) T cells and Ig(+)/CD19(+) B cells and plasma cells, lesions were divided into T-type and B-type lesions, respectively. The levels of IL-8 were significantly higher in the culture supernatants of PL-MNC in the T-type lesions and were positively correlated with the proportion of macrophages/dendritic cells (CD11c(+) cells) and CD4(+) T cells. Such a correlation was not shown in B-type lesions. CONCLUSION: These results suggest that PL-MNC are a significant source of IL-8, which is probably an important chemokine for the migration and function of different cell types at the site of chronic inflammation.     

The role of immune cytokines in the pathogenesis of periapical lesions

Abstract Bacterial infection of the dental pulp results in pulpal destruction, and subsequently stimulates an inflammatory cell response and destruction of bone in the periapex. Bacterial components, including lipopolysaccharides, induce the production of many polypeptide mediators, or cytokines, by inflammatory cells. These cytokines, which include macrophage-derived interleukin-1 beta, interleukin-1 alpha and tumor necrosis factor, and lymphocyte-derived lymphotoxin, have been shown to potently stimulate bone resorption and to inhibit reparative bone formation in vitro and in vivo. This review presents the hypothesis that immune cytokines play a major role in the pathogenesis of periapical lesions.     

Enzyme histochemical characterization of mononuclear cells in human dental periapical chronic inflammatory lesions

Abstract – Cell infiltrates in sections of paraffin-embedded tissue of 36 human periapical inflammatory lesions (15 granulomas and 21 cysts) were examined by staining for acid α-naphthyl acetate esterase (ANAE). Thirty-four of the lesions showed ANAE reactive T lymphocytes, plasma cells and cells of the monocyte/macrophage cell line. Large granular lymphocytes (NK cells) could not be identified with certainty among the ANAE positive cells. Two specimens were free of ANAE reactive cells. Differential cell counts on sections from 15 lesions (7 granulomas and 8 cysts) showed that T lymphocytes were the predominating ANAE reactive cells (23%), followed by plasma cells (15%) and monocytes/macrophages (11%). 51% of the inflammatory cells were ANAE negative. There was no marked difference between the granulomas and the cysts. Inhibition with NaF (10–100 mM) gave a gradual reduction in number of ANAE positive cells, some macrophages being the only cells resistant to 100 mM NaF. The results suggest that both humoral and cellular immune reactions are likely to occur in periapical inflammatory lesions.     

Distinct Th1, Th2 and Treg cytokines balance in chronic periapical granulomas and radicular cysts

J Oral Pathol Med (2010) 39 : 250–256 Background: Periapical lesions are a host response that involves immune reaction to prevent dissemination of bacteria from an infected root canal. The purpose of this study was to evaluate the levels of nitric oxide (NO), IL‐4, TGF‐β, tumor necrosis factor‐α (TNF‐α), and interferon‐γ (IFN‐γ) in chronic periapical lesions and to determine their possible association with clinical and radiographic parameters. Methods: Seventeen human radicular cysts and 30 periapical granulomas were used in this study. Cytokines and NO were assessed by enzyme‐linked immunosorbent assay and by the Griess reaction respectively confirmed by immunohistochemical. Results: TNF‐α and IFN‐γ were detected in 10% of granulomas and in 41.2% and 70% of radicular cysts. IL‐4 was reactive in 24% of cysts, and TGF‐β was positive in all samples. Patients with tenderness showed significantly higher levels of IFN‐γ and IL‐4 (P < 0.05). Swelling was associated with high levels of TNF‐α, IFN‐γ, and IL‐4 (P < 0.05). Lesions presenting bone resorption were associated with high levels of NO (P < 0.05). Conclusions: Periapical granulomas display a regulatory environment characterized by high TGF‐β and low inflammatory cytokine levels, while radicular cysts has mist Th1 and Th2 inflammatory reaction with the presence of IFN‐γ, TNF‐α, and IL‐4.     

Production of interleukin‐8 in vitro by mononuclear cells isolated from human periapical lesions

Introduction: Interleukin‐8 (IL‐8) is an important mediator of inflammation. However, little is known about its production in chronic dental periapical lesions and this was the main aim of this work. Methods: Inflammatory cells were isolated from clinically different periapical lesions and analyzed by morphological criteria. The mononuclear cells were isolated, phenotypically analyzed by immunocytochemistry and cultivated in vitro. IL‐8 was measured in culture supernatants of these periapical lesion mononuclear cells (PL‐MNC) using a microbeads fluorescence assay. Results: We found a relatively high production of IL‐8 in 19 out of 21 periapical lesions included in the study. The level of IL‐8 and the proportion of neutrophil granulocytes were significantly higher in the group of symptomatic lesions, compared to the asymptomatic lesions, but there was no statistically significant correlation between these parameters. According to the predominance of CD3⁺ T cells and Ig⁺/CD19⁺ B cells and plasma cells, lesions were divided into T‐type and B‐type lesions, respectively. The levels of IL‐8 were significantly higher in the culture supernatants of PL‐MNC in the T‐type lesions and were positively correlated with the proportion of macrophages/dendritic cells (CD11c⁺ cells) and CD4⁺ T cells. Such a correlation was not shown in B‐type lesions. Conclusion: These results suggest that PL‐MNC are a significant source of IL‐8, which is probably an important chemokine for the migration and function of different cell types at the site of chronic inflammation.     

Presence of natural killer cells in human chronic periapical lesions

Natural killer (NK) cells are lymphokl in nature and appear to kill target cells (neoplastic and virus-infected cells) without apparent prior immunization. Ten human chronic periapical lesions were examined for the presence of these cells. The lesions were collected, frozen in liquid nitrogen, and sectioned. They were then stained with an indirect immunoperoxidase procedure for the presence of human NK ceils. Human tonsils and human periapical scar tissue were used as positive and negative controls. The results showed absence of NK cells in scar tissue and the presence of NK cells in tonsils and all samples of human periapical lesions. NK cells may play a defensive role in controlling root canal infections or, possibly, a role in its pathogenesis.     

牙根尖周区病变的影像学诊断之惑与鉴别之道

根尖周区病变可能由牙髓源性感染所引起,也可能为非牙髓源性造成.非牙髓源性病变如果出现在牙髓坏死或曾行根管治疗的患牙根尖周时,很可能导致误诊误治甚至耽误病情.本文对可能出现在牙齿根尖周区透射影病变的影像诊断及其鉴别诊断进行了系统总结,为临床诊治提供参考.     

Detection of epidermal growth factor receptor in inflammatory periapical lesions

Epithelial cell proliferation is often observed in periapical lesions of endodontic origin. The mechanisms which stimulate the epithelial cell rests of Malassez to proliferate are not understood fully. Fifteen inflammatory periapical lesions (10 granulomas and five cysts) obtained from periapical surgery and six additional periapical lesions (four granulomas and two cysts) collected from extracted teeth were examined using immunohistochemical staining and ¹²⁵I-EGF (epidermal growth factor) binding assay to detect the presence of epidermal growth factor receptor. The results indicated that the periapical lesions without epithelial cell proliferation had a weak immunoperoxidase staining or low specific binding of i²⁵I-EGF. In contrast, the periapical lesions with epithelial cell proliferation and cyst formation exhibited a strong immunoperoxidase staining in the epithelial cells or high specific binding of ¹²⁵I-EGF.     

Deposits of immunoglobulins and complement factor C3 in human dental periapical inflammatory lesions

Abstract – Thirty-five human dental periapical lesions were studied by immunofluorescence technique using polyclonal anti-IgG (F(ab)₂), anti-IgM (F(ab)₂), anti-IgA (F(ab)₂), anti-IgE and anti-C3c as well as monoclonal anti-IgE. Prewashed ethanol-fixed specimens showed a great number of plasma cells staining for IgG. Cells containing IgA, IgM or IgE were also seen. Deposits of immunoglobulins and C3c suggestive of immune complexes were demonstrated using a double staining technique combining FITC-labeled immunoglobulins with TRITC-conjugated C3c. The complexes were located intracellularly in macrophages, as well as in vessel walls and in the basement membrane zone of proliferating epithelium. Immune complexes may be involved in the epithelial proliferation in those granulomas which lead to cyst formation. Monoclonal anti-IgE demonstrated plasma cells and mast cells, as well as intercellular IgE in epithelial strands of granulomas. The role of IgE in the epithelium is obscure. The study strongly indicates the involvement of hypersensitivity reactions type I and III in periapical inflammatory lesions.     

Mast cells in periapical lesions: potential role in their pathogenesis

J Oral Pathol Med (2010) 39 : 257–262 Objective: The aim of this study was to qualitatively and semi‐quantitatively analyze mast cells in periapical lesions. Materials and methods: Biopsy specimens of 96 periapical lesions were stained with hematoxylin–eosin, histochemical Giemsa and immunohistochemical CD 117 (C kit) antibody. Mast cell count below 100 mast cells on 1000 fields of high power magnification was noted as ‘negative’, 101–400 as ‘mild’, 401–800 cells as ‘moderate’, and over 800 cells as ‘severe’. Results: Mast cells are found in 68 (70.8%) lesions. The presence of mast cells was greater in cysts than in granulomas (P < 0.0028). There was no difference in semi‐quantitative expression of CD 117 in granulomas and cysts (P > 0.05). Mast cells were placed in both: inflammatory infiltrate and in fibroblastic areas of periapical lesions, and their presence was most frequently mild to moderate. Conclusions: The findings of present study could suggest a role of mast cells in regulation of cellular immune mechanisms in periapical lesions, balancing between alterative and reparatory processes in inflamed periapical tissue.     

Nonendodontic periapical lesions: a retrospective study in Chile

AIM: To determine the frequency with which the histopathological diagnosis of periapical lesions contributes to a change in the clinical diagnosis. METHODOLOGY: Cases having a clinical diagnosis of disease resulting from dental pulp necrosis were selected from the database of the Oral Pathology Reference Institute between 1975 and 2005. Cases with different histopathological diagnoses were determined and information about age and gender of the patient, location of associated tooth, pulp status and the histopathological diagnosis were recorded. The percentage of nonendodontic periapical lesions was then determined. RESULTS: In the 30-year period, 32,423 [corrected] biopsy specimens were received. Overall 4006 (9.13%) had a clinical diagnosis of pulpal necrosis with associated pathosis in the periradicular area. Within this group, 26 cases (0.65%) had a histopathological diagnosis of nonendodontic pathology. Keratocystic odontogenic tumour was the most frequent nonendodontic lesion (11 cases) in the periradicular region followed by central giant cell granuloma (three cases), chronic sinusitis (three cases) and one case each of the following lesions: nasopalatine duct cyst, lateral periodontal cyst, calcifying cystic odontogenic tumour, ameloblastic fibroma, squamous odontogenic tumour, cemental dysplasia, haemangioma, foreign body cell granuloma and amalgam tattoo. CONCLUSIONS: The histopathological study of periapical pathosis can occasionally reveal nonendodontic lesions. Odontogenic tumours made up the largest group.     

Minimally invasive periapical curettage of foreign materials in periapical lesions using a fiberscope

The design and development of a new fine fiberscope (1.0 mm outer diameter) is described, that includes an irrigation system for endoscopic use. This effectively allows visualisation of fields involved in periodontal disease. This fiberscope has been used in our clinic for seven years to diagnose and treat periapical and periodontal lesions through fistulae and periodontal pockets. The fiberscope has been applied to endodontic surgery for the inspection of root apices and the denuded root surfaces, in addition to the cut root face, rootend cavity and root-end filling after root-end resection. The advantages of endoscopy compared to surgical microscopy are portability and easy adjustment of direct viewing angle to examine around corners without the use of additional mirrors. Furthermore, the fiberscope can be utilised through the sinus tract or a minimal incision without the need for surgical flaps to observe the root surface, periapical tissue and foreign materials before, during and after curettage. The system requires little local anaesthesia, no large incisions, no opening flaps and no sutures. As a result, postoperative symptoms are minimised. Periapical curettage using a fiberscope represents a useful and minimally invasive surgical procedure.     

Kinetics of Th17‐related cytokine expression in experimentally induced rat periapical lesions

Th17‐related cytokines are essential factors in various pathological states, including inflammatory bone destruction. This study investigated the contribution of Th17‐related cytokines to the progress of experimentally induced rat periapical lesions. Periapical pathoses were induced by unsealed exposure of the pulp chamber of the lower first molars. A variety of immunocompetent cells, including CD68⁺ macrophages, Ia antigen⁺ cells and TCRαβ⁺ T cells, were observed in the lesions. The expression levels of Th17‐related cytokines, IL‐17 and IL‐23, and of pro‐inflammatory cytokines, IL‐1β and IL‐6, were significantly increased at 14 days (expansion stage) compared with normal periapical tissues. The expression levels of Foxp3, a regulatory T cell (Treg)‐related gene, and of IL‐10, an anti‐inflammatory cytokine, were higher at 28 days (chronic stage) than at 14 days. These findings suggest that Th17‐related cytokines may be primary contributors to the initiation of periapical bone destruction, and that lesion expansion may be regulated by anti‐inflammatory mediators.     

Analysis of immunoglobulin-synthesizing cells in human dental periapical lesions by in situ hybridization and immunohistochemistry

Immunoglobulin (Ig) kappa (κ) and lambda (λ) light chain mRNA-expressing cells were investigated by in situ hybridization (ISH) to assess the local humoral immune response in human dental periapical lesions. Twenty-seven biopsy samples (17 periapical granulomas and 10 radicular cysts) were examined. Both types of light chain mRNA-positive cells were detected in formalin-fixed/paraffin-embedded tissue sections in all samples. Plasma cells showed weak to strong cytoplasmic staining with both probes and background staining was negligible. The ISH methodology is specific and sensitive in detecting Ig light chain mRNAs and retains cell morphology well. κ to λ ratios showed moderate variability for both granulomas and cysts (mean=1.66±0.85 SD. 1.47±0.51, respectively). There was no significant difference in light chain distribution between granulomas and cysts. Ig κ and λ light chain proteins were also studied by immunohistochemistry (IHC) but the results were disappointing due to excessive background staining. This study confirms that Ig is locally produced in periapical lesions and that the ISH method localises Ig light chain-containing cells better than IHC. The wide variability in κ/λ ratio may support the concept of non-specific multibacterial infection in these lesions.     

Correlation between clinical and histopathological diagnoses in periapical inflammatory lesions

Aim: The purpose of the present study was to evaluate the correlation between clinical and histopathological diagnoses of periapical inflammatory lesions, focusing mainly on cystic conditions. Methods: Files dating from 1998 to 2006 at the Oral Pathology Laboratory, School of Dentistry, Alfenas Federal University, Brazil, were reviewed to identify cases with histopathological diagnoses of periapical inflammatory lesions. A total of 1788 files were analyzed, and 255 cases were identified with clinical diagnoses of periapical inflammatory lesions. Results: The most prevalent clinical diagnosis was apical periodontal cyst (59%), followed by periapical granuloma (20%), and dentoalveolar abscess (2%). After histopathological analysis, 53% of the cases represented apical periodontal cyst, 42% periapical granuloma, and 5% dentoalveolar abscess. Conclusions: The outcomes of the present study show a high prevalence of periapical cysts among periapical inflammatory lesions. Moreover, this study highlights the importance of histopathological evaluation for the correct diagnosis of periapical inflammatory lesions.     

Production of IL‐10 and IL‐12 by antigen‐presenting cells in periapical lesions

J Oral Pathol Med (2010) 39 : 690–696 Background: Interferon‐γ (IFN‐γ) plays an important role in the pathogenesis of periapical lesions. Its expression is up‐regulated by interleukin (IL)‐12) and down‐regulated by IL‐10. The aim of this work was to study the cellular source of these cytokines and their mutual interactions in human periapical lesions. Methods: Mononuclear cells, macrophages and dendritic cells were isolated from periapical lesions using plastic adherence and osmotic gradients. Cytokines were measured in culture supernatants by a microbeads fluorescence assay. Phenotypic characteristics of cells were studied by immunocytochemistry, whereas allostimulatory activity of antigen‐presenting cells was tested using a mixed leukocyte reaction. Results: We observed the positive correlations between the levels of IL‐12 and IFN‐γ as well as IL‐12 and IL‐10 in cultures of mononuclear cells. As IL‐10 and IL‐12 are produced by dendritic cells and activated macrophages, we examined their contribution to the production of these cytokines. Macrophages, CD14⁺ adherent cells, produced high levels of IL‐10 and very low levels of IL‐12. In contrast, non‐adherent, strongly HLA‐DR⁺ dendritic cells, potent stimulators of the alloreactive T‐cell response, produced low levels of IL‐10 and moderate levels of IL‐12. Dendritic cells stimulated the production of IFN‐γ by allogeneic CD4⁺ T cells. In contrast, the level of IFN‐γ was significantly decreased and the production of IL‐10 was enhanced by addition of macrophages to the culture system. Conclusion: Our results suggest that a fine balance between the production of IL‐10 and IL‐12 by different antigen‐presenting cells, through IFN‐γ, may control the course of chronic inflammation in periapical lesions.     

Quantitative analysis of lymphocytes and their subsets in periapical lesions

The relative proportions of lymphocytes and their subsets in periapical lesions associated with untreated teeth and endodontically treated teeth were compared. Nine periapical lesions associated with previously untreated teeth and six persistent lesions associated with previously root treated teeth which had good quality root canal fillings and coronal seals were selected from a total of 41 samples. Clinical and radiographic features of each lesion were recorded. Serial frozen sections were stained using immunohistochemical methods and monoclonal antibodies against CD20, CD3, CD4 and CD8 to identify B, T, T helper (Th) and T suppressor (Ts) lymphocytes, respectively. Ten microscopic fields, representing the most dense cellular inflammatory infiltrate were selected per specimen and cell numbers were estimated, as a proportion of lesion area, using a point counting method. The periapical lesions associated with untreated teeth had a denser inflammatory cell infiltrate. The proportion of total lymphocytes was significantly higher in the untreated group of lesions ( P < 0.01). The proportions of B ( P < 0.01), T ( P < 0.001) and Th cells ( P < 0.01) were significantly higher in untreated teeth. The ratios of Th/Ts cells ( P < 0.05) and T/total lymphocytes ( P < 0.01) were also significantly different between the two types of lesion. The results show a difference in the inflammatory cell infiltrate and relative proportions of T, B and T helper cells in the two groups of lesions. This indicates that future studies of periapical lesions should take into account the clinical history of the associated teeth.