Pro‐inflammatory cytokine levels in human apical periodontitis: Correlation with clinical and histological findings

This study aimed to compare the levels of tumour necrosis factor‐alpha (TNF‐α), interleukin‐1 beta (IL‐1β) and interleukin‐6 (IL‐6) between apical periodontitis lesions with different clinical and histological features. Based on clinical data and history of disease, 100 human apical periodontitis lesions were categorised as either asymptomatic or symptomatic lesions. According to histological examination, lesions were divided into periapical granulomas and radicular cysts. Pulp tissues of 25 impacted wisdom teeth were used as controls. Homogenised tissue samples were centrifuged and supernatants were used for the determination of cytokine levels by enzyme‐linked immunosorbent assay. Significantly higher levels of IL‐1β and IL‐6 were found in symptomatic lesions compared with asymptomatic lesions and control tissues (P < 0.001, P < 0.001, respectively). The concentration of IL‐1β was significantly higher in radicular cysts compared with periapical granulomas (P = 0.003). Symptomatic lesions, as judged by high local production of IL‐1β and IL‐6, represent an immunologically active stage of the disease.     

The role of Toll‐like receptors 2 and 4 on reactive oxygen species and nitric oxide production by macrophage cells stimulated with root canal pathogens

Introduction: Periapical lesions arise as a result of the activation and interaction of the host immune responses against root canal infection. Recently identified Toll‐like receptors (TLR) seem to be involved in the recognition and development of immune responses against a myriad of microorganisms. However, very little information is available on the role of TLR in the induction of periapical lesions. Method: The role of TLR‐2 and TLR‐4 in the activation of murine macrophages stimulated using Fusobacterium nucleatum and Peptostreptococcus anaerobius was investigated. The production of nitric oxide (NO) and reactive oxygen species (ROS) was assessed. Results: The results demonstrate that TLR‐2 and TLR‐4 are involved in the production of ROS by activated macrophages. The microorganisms induced similar levels of NO production by TLR‐2‐competent and TLR‐2‐deficient macrophages, regardless of the addition of interferon‐γ (IFN‐γ), ruling out a role for TLR‐2 in the NO production induced by these bacteria. Only P. anaerobius induced NO production by TLR‐4‐competent macrophages without the addition of IFN‐γ. However, after IFN‐γ addition, F. nucleatum induced macrophage NO production. Therefore, NO production stimulated by IFN‐γ and these microorganisms seems to be TLR‐4‐independent. Conclusion: TLR‐2 seems to be involved in the induction of ROS production by macrophages in response to prevalent root canal bacteria, while only F. nucleatum induced ROS production by TLR‐4‐competent macrophages. Both microorganisms significantly induced large amounts of NO independent of TLR‐2 and TLR‐4. We conclude that microorganisms may participate in the induction and progression of periapical lesions through NO and ROS production by activated macrophages.     

Serum cytokine levels in periodontitis patients in relation to the bacterial load

Background: Periodontitis is a local inflammatory disease that also has some systemic effects. We investigated the levels of interferon (IFN)‐γ, tumor necrosis factor (TNF)‐α, and interleukin (IL)‐2, ‐4, ‐5, and ‐10 in the serum of patients with periodontitis in relation to the bacterial load in the dental plaques. Methods: Serum cytokine levels in patients with generalized periodontitis and healthy control groups were determined using the cytometric bead array kit. Bacterial load in the dental plaque was determined semiquantitatively by real‐time polymerase chain reaction. The proportions of different lymphocyte subsets were determined in the peripheral blood of patients with periodontitis by flow cytometry. Finally, relationships between the bacterial load in the subgingival plaques of patients with periodontitis and levels of cytokines and counts of lymphocyte subsets were established. Results: Serum levels of IFN‐γ, TNF‐α, and IL‐10 were significantly increased, whereas those of IL‐2 were significantly decreased in patients with periodontitis compared to healthy controls. Increased serum levels of IFN‐γ and TNF‐α in patients with periodontitis were associated with the enhanced dental plaque load with Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) and Porphyromonas gingivalis, respectively. Finally, as revealed by analysis of lymphocyte populations, the presence of A. actinomycetemcomitans and Trepomena denticola was associated with an increased population of CD3^?/CD16⁺ and CD3⁺/CD8⁺ cells, respectively. Conclusion: Certain periodontal pathogens could be associated with an increased level of proinflammatory cytokines in the peripheral blood and thus increased risk of systemic diseases.     

Partial- and full-mouth scaling and root planing in type 2 diabetic subjects: a 12-mo follow-up of clinical parameters and levels of cytokines and osteoclastogenesis-related factors

Santos VR, Ribeiro FV, Lima JA, Miranda TS, Feres M, Bastos MF, Duarte PM. Partial‐ and full‐mouth scaling and root planing in type 2 diabetic subjects: a 12‐mo follow‐up of clinical parameters and levels of cytokines and osteoclastogenesis‐related factors. J Periodont Res 2012; 47: 45–54. © 2011 John Wiley & Sons A/S Background and Objective: The aim of this study was to evaluate the effects of full‐mouth scaling and root planing (FMSRP) and partial‐mouth scaling and root planing (PMSRP), up to 12 mo after treatment, on clinical parameters, and levels of cytokines and osteoclastogenesis‐related factors in type 2 diabetic subjects with chronic periodontitis. Material and Methods: Thirty‐four subjects received FMSRP (n = 17) or PMSRP (n = 17) within 24 h or in multiple sessions, respectively. Clinical parameters and local levels of tumor necrosis factor‐α (TNF‐α), interferon‐γ (IFN‐γ), interleukin (IL)‐17, IL‐23, IL‐4, receptor activator of NF‐β ligand and osteoprotegerin were assessed at baseline, and 3, 6 and 12 mo after therapies. Results: Clinical parameters improved after both therapies (p < 0.05), and no between‐group differences were observed at any time‐point (p > 0.05). Overall, there were no considerable differences in the local levels of the biomarkers studied between groups (p > 0.05). The IL‐23 concentration and total amount of IFN‐γ increased in the FMSRP group and decreased in the PMSRP group from baseline to 3 mo and from baseline to 6 mo, respectively (p < 0.05). Conclusion: Both PMSRP and FMSRP promoted benefits in clinical parameters and showed a similar modulation of cytokines and osteoclastogenesis‐related factors at 12 mo in type 2 diabetic subjects.     

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.     

Immunoexpression of TNF-α and TGF-β in central and peripheral giant cell lesions of the jaws

J Oral Pathol Med (2012) 41 : 194–199 Background: Peripheral giant cell lesion (PGCL) is a reactive process associated with a local irritating factor that shows low recurrence after treatment, especially if the irritating factor is eliminated. On the other hand, central giant cell lesion (CGCL) presents a variable clinical behavior ranging from slow and asymptomatic growth without recurrence to rapid, painful and recurrent growth. Our aim was to compare the immunoexpression of tumor necrosis factor‐alpha (TNF‐α) and transforming growth factor‐beta (TGF‐β) in CGCL and PGCL. Methods: Twenty CGCL and 20 PGCL were selected for analysis of the immunoexpression of TNF‐α and TGF‐β in multinucleated giant cells (MGC) and mononucleated cells (MC). Results: The PGCL showed lightly higher expression of TNF‐α than CGCL. In comparison with PGCL, the CGCL showed higher expression of TGF‐β in MC and MGC (P < 0.05) and in total cells (P < 0.05). Significant positive correlation was found between expressions of TGF‐β and TNF‐α in CGCL (P < 0.05). Conclusions: Our results suggest that, in CGCL, coordinated interactions between TGF‐β and TNF‐α may be important for osteoclastogenesis and bone resorption. PGCL occasionally cause bone resorption but to a lower extent, a fact that might be explained by the lower expression of TGF‐β in these lesions.     

Saliva and Serum Levels of B‐Cell Activating Factors and Tumor Necrosis Factor‐α in Patients With Periodontitis

Background: B‐lymphocytes play a central and critical role in the adaptive immune response against invading pathogens. This study evaluates saliva and serum levels of APRIL (a proliferation‐inducing ligand), B‐cell activating factor (BAFF), tumor necrosis factor‐α (TNF‐α), interleukin (IL)‐6, and IL‐10 in patients with chronic periodontitis (CP) or aggressive periodontitis (AgP) and periodontally healthy individuals. Methods: Twenty‐five patients with AgP, 20 patients with CP, and 20 periodontally healthy individuals were included. Smoking status was recorded, and all individuals were divided into non‐smokers and smokers. Saliva and serum samples were collected before clinical periodontal measurements. APRIL, BAFF, TNF‐α, IL‐6, and IL‐10 levels in serum and saliva samples were determined by enzyme‐linked immunosorbent assay. Statistical analysis was performed using multivariate analysis of variance and bivariate correlation. Results: Serum and saliva levels of TNF‐α, APRIL, BAFF, IL‐6, and IL‐10 were similar in CP and AgP groups. Serum levels of TNF‐α, APRIL, and BAFF and saliva levels of BAFF were significantly higher in periodontitis groups than healthy controls (P <0.05). Non‐smokers with CP or AgP had lower levels of saliva TNF‐α and APRIL and serum APRIL and IL‐6 than smokers with CP or AgP (P <0.05). Saliva APRIL and serum TNF‐α and IL‐6 levels were significantly higher in healthy smokers than healthy non‐smokers (P <0.05). Clinical periodontal parameters correlated positively with TNF‐family cytokines and negatively with IL‐10 (P <0.05). Conclusions: Within the limits of this study, it may be suggested that elevated salivary and serum TNF‐α, APRIL, and BAFF in patients with periodontitis may contribute to the dominance of B cells in periodontitis lesions. Moreover, higher levels in healthy smokers than non‐smoking counterparts may play a role in detrimental effects of smoking on periodontal tissues.     

l‐arginine‐dependent nitric oxide production of a murine macrophage‐like RAW 264.7 cell line stimulated with Porphyromonas gingivalis lipopolysaccharide

The aim of this study was to determine nitric oxide (NO) production of a murine macrophage cell line (RAW 264.7 cells) when stimulated with Porphyromonas gingivalis lipopolysaccharides (Pg‐LPS). RAW264.7 cells were incubated with i) various concentrations of Pg‐LPS or Salmonella typhosa LPS (St‐LPS), ii) Pg‐LPS with or without l ‐arginine and/or N^G‐monomethyl‐l ‐arginine (NMMA), an arginine analog or iii) Pg‐LPS and interferon‐γ (IFN‐γ) with or without anti‐IFN‐γ antibodies or interleukin‐10 (IL‐10). Tissue culture supernatants were assayed for NO levels after 24 h in culture. NO was not observed in tissue culture supernatants of RAW 264.7 cells following stimulation with Pg‐LPS, but was observed after stimulation with St‐LPS. Exogenous l ‐arginine restored the ability of Pg‐LPS to induce NO production; however, the increase in NO levels of cells stimulated with Pg‐LPS with exogenous l ‐arginine was abolished by NMMA. IFN‐γ induced independent NO production by Pg‐LPS‐stimulated macrophages and this stimulatory effect of IFN‐γ could be completely suppressed by anti‐IFN‐γ antibodies and IL‐10. These results suggest that Pg‐LPS is able to stimulate NO production in the RAW264.7 macrophage cell model in an l ‐arginine‐dependent mechanism which is itself independent of the action of IFN‐γ.     

The concentration of TNF-alpha correlate with number of inflammatory cells and degree of vascularization in radicular cysts

Objective: To correlate values of tumor necrosis factor‐alpha (TNF‐α) depending on the count of inflammatory cells with degree of vascularization in cystic fluid of radicular cysts. Material and methods: We investigated TNF‐α concentration in 43 radicular cysts obtained from patients undergoing surgery, under local anaesthesia, and after aspiration of cystic fluid from non‐ruptured cysts by enzyme‐linked immunosorbent assay assay in respect of different clinical parameters as well as by histomorphometric analyses. Results: Significantly higher concentration of TNF‐α is associated with smaller radicular cysts, higher protein concentration in cystic fluid as well as with higher presence of inflammatory cells, and increased degree of vascularization in pericystic tissues and cyst wall thickness. Conclusions: We believe that determination of TNF‐α in cystic fluid simultaneously with other parameters can be an additional parameter for clinical diagnosis of inflammed cysts.     

Is There an Interaction Between Polycystic Ovary Syndrome and Gingival Inflammation?

Background: The aim of this study is to evaluate the gingival crevicular fluid (GCF), saliva, and serum concentrations of tumor necrosis factor‐α (TNF‐α), TNF‐α receptor‐1 (TNF‐αR1), TNF‐αR2, and interleukin‐6 (IL‐6) in non‐obese females with polycystic ovary syndrome (PCOS) and either clinically healthy periodontium or gingivitis. Methods: Thirty‐one females with PCOS and healthy periodontium, 30 females with PCOS and gingivitis, and 12 systemically and periodontally healthy females were included in the study. GCF, saliva, and serum samples were collected, and clinical periodontal measurements, body mass index, and Ferriman‐Gallwey score (FGS) were recorded. Sex hormones, cortisol, and insulin levels were measured. TNF‐α, TNF‐αR1, TNF‐αR2, and IL‐6 were determined by enzyme‐linked immunosorbent assay. Kruskal‐Wallis followed by Bonferroni‐corrected post hoc Mann‐Whitney U tests were used to analyze the data. Results: The PCOS + gingivitis group revealed significantly higher GCF, saliva, and serum IL‐6 concentrations than the PCOS + healthy group (P <0.0001). The two PCOS groups exhibited significantly higher saliva TNF‐α concentrations than the control group (P = 0.024 and P = 0.013, respectively). The FGS index was significantly higher in the PCOS + gingivitis group than the PCOS + healthy group (P = 0.030). The PCOS + gingivitis group revealed significantly higher insulin concentration than the PCOS + healthy and control groups (P = 0.014 and P <0.0001, respectively). Serum TNF‐α, TNF‐αRs, and serum, GCF, and salivary IL‐6 levels correlated with the clinical periodontal measurements. Conclusions: PCOS and gingival inflammation appear to act synergistically on the proinflammatory cytokines IL‐6 and TNF‐α. Thus, PCOS may have an impact on gingival inflammation or vice versa. Additional studies are warranted to clarify the possible relationship between PCOS and periodontal disease.     

Inflammation‐related cytokines in oral lichen planus: an overview

Cytokines are powerful mediators which play a central role in both innate and adapted immune responses. Aberrant productions of cytokines may lead to the onset of immune deficiency, allergy or autoimmunity, which are involved in the mechanisms of various immune‐mediated inflammatory diseases. Oral lichen planus (OLP) is a chronic inflammation disease affecting the oral mucosa with unknown aetiology. Previous studies have described the abnormal expression patterns of various inflammation‐related cytokines, such as IL‐1, 2, 4, 5, 6, 8, 10, 12, 17, 18, TGF‐β, IFN‐γ and TNF‐α, in lesions, saliva, serum and peripheral blood mononuclear cells from patients with OLP, which may reflect the immune dysregulation status and emerge as central players in the immunopathogenesis of OLP. Besides, the gene polymorphisms of several cytokines such as IFN‐γ, TNF‐α, IL‐4, IL‐10 have been found to be involved in the susceptibility of OLP. In this review, we gave a brief introduction of the characteristics and biological functions of these inflammation‐related cytokines and summarized for the first time the current knowledge on the involvement of inflammation‐related cytokines in OLP. Further research on the exact roles of these cytokines will aid the understanding of the pathogenesis and the identification of novel therapeutic approaches of OLP.     

Whole‐Blood Cultures From Patients With Chronic Periodontitis Respond Differently to Porphyromonas gingivalis but not Escherichia coli Lipopolysaccharide

Background: Porphyromonas gingivalis lipid A heterogeneity modulates cytokine expression in human cells. This study investigates the effects of two lipid A isoforms of P. gingivalis, lipopolysaccharide (LPS)_1435/1449 and LPS₁₆₉₀, on the secretion of proinflammatory and regulatory cytokines in total blood cultures from patients with and without chronic periodontitis (CP). Methods: A cross‐sectional study was conducted in 38 systemically healthy individuals divided in two groups: 1) the CP group (n = 19), in which patients were diagnosed with CP; and 2) the no periodontitis (NP) group (n = 19), which included control patients without CP. Blood samples were collected from all patients, and whole‐blood cell cultures (WBCCs) were stimulated for 48 hours with P. gingivalis LPS_1435/1449 and LPS₁₆₉₀ and Escherichia coli LPS. Unstimulated WBCCs served as negative controls. The secretion of interferon‐γ (IFN‐γ), interleukin‐10 (IL‐10), and transforming growth factor‐β (TGF‐β) was detected in WBCC supernatants by enzyme‐linked immunosorbent assays. Results: E. coli LPS significantly increased the expression of all cytokines in WBCCs from both the NP and CP groups when compared to non‐stimulated cells (control treatment). P. gingivalis LPS preparations increased IFN‐γ levels in the CP group but not in the NP group when compared with controls (P <0.05). P. gingivalis LPS preparations also increased IL‐10 and TGF‐β levels in both CP and NP groups, but P. gingivalis LPS₁₆₉₀ showed a three‐fold increase on IL‐10 production in the NP group (P <0.05) when compared to P. gingivalis LPS_1435/144. Conclusions: These data demonstrate that WBCC cell populations obtained from healthy individuals and patients with CP may differ in the cytokine response to P. gingivalis but not E. coli LPS. This is consistent with the notion that CP alters the systemic WBCC response and that this can be detected by the different P. gingivalis LPS structures.     

Cytokines and bone-related factors in systemically healthy patients with chronic periodontitis and patients with type 2 diabetes and chronic periodontitis

Background: This study compares the levels of cytokines and bone‐related factors in the gingival crevicular fluid (GCF) of systemically healthy patients with chronic periodontitis (CP); and better‐controlled, and poorly controlled patients with type 2 diabetes and CP. Methods: Thirty‐seven patients with type 2 diabetes and CP and 20 systemically healthy patients with CP were enrolled in this study. The patients with diabetes mellitus were categorized as better‐controlled (n = 17; HbA_1c levels ≤8%) or poorly controlled (n = 20; glycated hemoglobin values >8%). Levels of tumor necrosis factor‐α, interleukin (IL)‐4, interferon (IFN)‐γ, IL‐23, IL‐17, soluble receptor activator of nuclear factor‐kappa B ligand (sRANKL), and osteoprotegerin (OPG) in GCF of diseased sites were analyzed by enzyme‐linked immunosorbent assay. Results: Type 2 diabetes mellitus, as a whole, upregulates the levels of OPG, sRANKL, IFN‐γ, IL‐17, and IL‐23 and downregulates the production of IL‐4 in sites with CP (P <0.05). Better‐controlled individuals exhibited the highest levels of IFN‐γ, whereas poorly controlled patients presented the highest levels of IL‐17 (P <0.05). There were no differences in the levels of tumor necrosis factor‐α, OPG, and IL‐23 among systemically healthy, better‐controlled, and poorly controlled patients with diabetes (P >0.05). Conclusions: Increased levels of proinflammatory cytokines and RANKL were observed in the GCF of patients with type 2 diabetes with CP, compared to patients without diabetes. In addition, poor or good glycemic status seems to modulate osteo‐immunoinflammatory mediators in a different manner.     

Cytokine profiles in parotid saliva from HIV‐1‐infected individuals: changes associated with opportunistic infections in the oral cavity

The purpose of this study was to quantitate levels of cytokines in parotid saliva of subjects infected with human immunodeficiency virus‐1 (HIV‐1) and to determine if the cytokine profiles differ in subjects with an oral opportunistic infection, i.e., candidiasis or oral hairy leukoplakia. Parotid saliva samples were obtained from HIV‐infected individuals with or without candidiasis or oral hairy leukoplakia and from healthy controls and were assessed by ELISA for levels of interleukin (IL)‐1, IL‐2, IL‐4, IL‐5, IL‐10, transforming growth factor‐β, tumor necrosis factor‐α and interferon (IFN)‐γ. Saliva from HIV‐infected subjects with oral candidiasis had significantly higher levels of IFN‐γ than that seen in HIV‐infected individuals with no oral disease and significantly higher levels of IL‐2, IL‐5 and IFN‐γ than saliva of healthy controls. No significant difference was seen in cytokine levels in saliva from HIV‐infected subjects with no oral infections and healthy controls. The HIV‐infected subjects with oral hairy leukoplakia displayed significantly higher levels of both IL‐1α and IFN‐γ compared with the HIV and no oral disease group and a higher level of IFN‐γ than seen in saliva from the healthy control group. In comparing cytokine levels from both HIV and oral disease groups, significant differences were detected in levels of IL‐5 and IL‐10. These results indicate that the profile of salivary cytokines is altered as a result of the oral opportunistic infection candidiasis or oral hairy leukoplakia and also by concurrent HIV infection.     

Evaluation of MicroRNA‐146a and Its Targets in Gingival Tissues of Patients With Chronic Periodontitis

Background: MicroRNAs (miRNAs) are a group of small non‐coding RNAs that play an important role in the regulation of gene expression. miRNA‐146a (miR‐146a), a member of the miR‐146 family, is involved in the control of inflammation. Periodontitis is a set of chronic inflammatory disorders of the tissues surrounding the teeth that lead to the breakdown of alveolar bone and tooth loss. In this study, expression levels of miR‐146a and its targets, including tumor necrosis factor (TNF)‐α, interleukin (IL)‐1β, and IL‐6, are evaluated in human patients with chronic periodontitis (CP). Methods: The study population consisted of 10 healthy controls and 20 individuals with CP. For each participant, clinical parameters including probing depth and clinical attachment level were measured, and a gingival tissue sample was collected. Levels of miR‐146a, TNF‐α, IL‐1β, and IL‐6 were quantified using real‐time polymerase chain reaction. Results: Levels of miR‐146a were significantly higher in patients with CP (P <0.001). There was a positive correlation between levels of miR‐146a and clinical parameters (P <0.05). Elevated miR‐146a was accompanied by a significant reduction in TNF‐α and IL‐6 (P <0.001). Conclusions: Patients with CP had higher levels of miR‐146a than healthy individuals, accompanied by reduced levels of TNF‐α and IL‐6. A positive relationship between miR‐146a levels and clinical parameters suggests a pathophysiologic role of miR‐146a in CP.     

Hepatocytes produce tumor necrosis factor-α and interleukin-6 in response to Porphyromonas gingivalis

Takano M, Sugano N, Mochizuki S, Koshi RN, Narukawa TS, Sawamoto Y, Ito K. Hepatocytes produce tumor necrosis factor‐α and interleukin‐6 in response to Porphyromonas gingivalis. J Periodont Res; 2012; 47: 89–94. © 2011 John Wiley & Sons A/S Background and Objective: The liver plays a major role in clearing systemic bacterial infections. In addition, inflammatory cytokines produced in the liver play a critical role in systemic cytokine levels. The aim of this study was to investigate the production of tumor necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6) by hepatocytes in response to periodontal pathogens. Material and Methods: The mouse hepatic carcinoma cell line Hepa‐1.6 and the mouse macrophage‐like cell line RAW 264 were co‐cultured in Transwell insert plates. Cells were stimulated with bacterial extracts prepared from Porphyromonas gingivalis and the induction of TNF‐α and IL‐6 was measured using real‐time PCR and ELISA. Results: After stimulation with bacteria, the induction of TNF‐α and IL‐6 was observed in RAW 264 cells and Hepa‐1.6 cells. Significant reduction of TNF‐α mRNA expression in Hepa‐1.6 cells was observed after treatment with antibody to TNF‐α. Conclusion: The results obtained in the present study show that P. gingivalis extract induces TNF‐α and IL‐6 in an in vitro liver model and that macrophage‐derived TNF‐α mediates the induction of TNF‐α in hepatocytes.     

Differentiation of radicular cyst and granulomas using computerized tomography

The purpose of this investigation was to study periapical lesions by means of computerized tomography to ascertain if this noninvasive method could be of value in distinguishing between radicular cysts and granulomas. Periapical radiographs were taken of the teeth of 60 human cadavers. Periapical radiolucencies were seen in conjunction with 33 teeth. Based on the periapical radiographs, an oral radiologist (J.P.) attempted to select 4 granulomas and 4 cysts from the 33 radiolucencies. Computerized tomography was performed on the root tips and the periapical lesions of these 8 teeth. The roots and periapical lesions were then surgically removed and prepared histologically for microscopic examination. In the tomographs, 7 of the periapical lesions had a cloudy appearance with a density similar to each other and to the surrounding soft tissue. In the eighth lesion a homogeneous dark area with a distinctly lower density could be distinguished from surrounding cloudy areas. Histologically, the dark area was shown to be an epithelialized cyst cavity. The other 7 lesions were granulomas. Thus, a cyst could be differentiated from periapical granulomas by computerized tomography because of a marked difference in density between the content of the cyst cavity and granulomatous tissue.