Expression and Distribution of Receptor Activator of Nuclear Factor Kappa B, Receptor Activator of Nuclear Factor Kappa B Ligand, and Osteoprotegerin in Periradicular Cysts

Interleukin 17 expression in periapical lesions from elderly patients

OBJECTIVE

To compare the expression of IL-17 in periapical lesions (cysts and granulomas) among elderly individuals and adults. We selected 20 periapical lesions of the elderly (12 granulomas and eight cysts) and 20 periapical lesions of adults (12 granulomas and eight cysts).

MATERIALS AND METHODS

Immunohistochemistry was performed using a specific antibody for IL-17. The slides were subdivided into five high magnification fields and then the images were observed through an optical microscope. According to the number of positive markings for the antibody, grades were given, ranging from 0 to 2.

RESULTS

The results demonstrate that there was no statistical difference when comparing the expression of IL-17 between cysts and granulomas of both groups (study group: cysts 0.7 ± 0.21 × granulomas 0.96 ± 0.58, p = .61; control group: cysts 0.37 ± 0.16 × granulomas 0.31 ± 0.23, p = .27). The comparison between adult (control group) and elderly patients (study group) showed a statistical difference both in cysts (study group: 0.7 ± 0.21 × control group: 0.37 ± 0.16, p = .007) and in granulomas (study group: 0.96 ± 0.58 × control group: 0.31 ± 0.23, p = .0009), in which elderly patients had a higher expression of interleukin 17, in relation to adult patients.

CONCLUSION

We concluded that elderly patients have a higher expression of IL-17 in both cysts and granulomas, when compared to adult patients.

Correlation Between Proinflammatory Cytokine Expression and Clinical Data in Apical Granuloma

INTRODUCTION

This study was intended to evaluate the expression of inflammatory cytokines commonly secreted by CD4+ T cells (IL-2, IL-5, IL-17, TGF-β, TNF-α, and IFN-γ) in apical granulomas and correlate with the clinical conditions and time elapsed since root canal treatment.

METHODS

Eighteen biopsy specimens obtained by periradicular surgery of teeth with post-treatment apical periodontitis and diagnosed as apical granuloma were available from the oral pathology laboratory. Silanized slides containing paraffin sections were used for immunohistochemical reactions. Images were analyzed by using an optical microscopy and each slide was subdivided into 5 fields at high magnification.

RESULTS

IFN-γ and TGF-β were the cytokines with the highest expression levels. There were statistically significant differences when comparing IL-2 and IFN-γ (P < .05), and IL-2 and TGF-β (P < .05). Comparison between the detected cytokines and clinical data and time of treatment demonstrated significant correlation (P < .05) between lower expression of IL-2 and the presence of painful symptoms, absence of sinus tract, and treatments performed more than 4 years before. It was also possible to observe a significant correlation between lower expression of IL-5 and treatments performed less than 4 years before (P < .05).

CONCLUSION

IFN-γ and TGF-β were highly expressed in apical granulomas. However, only IL-2 and IL-5 levels were associated with clinical data and time since previous root canal treatment.

Proinflammatory Cytokine Expression in Apical Periodontitis from Diabetic Patients

Diabetes mellitus has been regarded as a condition capable of influencing the evolution of periapical lesions. Therefore, this study evaluated the immunoexpression of IL-1β, TNF-α, and IL-17 in apical periodontitis from type 2 diabetic patients through immunohistochemistry. Twenty-six periapical lesions were selected, and the images obtained through immunohistochemistry reactions were analyzed. The statistical significance was set at p < 0.05. IL-1β expression was considered focal (54%), weak to moderate (38%), and strong (8%) in diabetics, and focal (46%), weak to moderate (31%), and strong (23%), in controls. TNF-α was focal (85%) and weak to moderate (15%) in diabetics, and focal (92%) and weak to moderate (8%), in controls. IL-17 was focal (8%), weak to moderate (46%), and strong (46%) in diabetics, and focal (62%), weak to moderate (8%), and strong (30%), in controls. The quantitative analysis revealed greater expression of IL-17, with a significant difference between IL-17 × IL-1β × TNF-α(p=0.0009) in the diabetic group. The cytokines IL-1β and TNF-α did not express statistical differences between the tested groups. The IL-17 showed higher immunoexpression in the diabetic group (p=0.047), which may suggest higher bone resorption activity in chronic apical periodontitis in this group of patients.

Evaluation of Receptor Activator of Nuclear Factor Kappa B Ligand, Osteoprotegerin, Osteopontin, and Tumor Necrosis Factor Alpha on Chronic Apical Periodontitis in Smokers

INTRODUCTION

Smoking can be considered a risk factor for chronic apical periodontitis (CAP). This study compared the immunoexpression of biomarkers receptor activator of nuclear factor kappa B ligand (RANKL), osteoprotegerin (OPG), osteopontin (OPN), and tumor necrosis factor alpha (TNF-α) in CAP in smokers and nonsmokers.

METHODS

Twelve smokers and 12 nonsmokers diagnosed with CAP and indicated for tooth extraction were selected. Exclusion factors were teeth with a diagnosis of root fracture, previous endodontic treatment, or endoperiodontal injury, in addition to individuals with systemic diseases, under 18 years of age, users of anti-inflammatory and/or antibiotics in the last 3 months, and drug users. Specimens were processed for histopathologic and immunohistochemical analysis.

RESULTS

Qualitative analysis of RANKL expression showed 66.66% weak/moderate and 33.33% strong in smokers and 100% weak/moderate in nonsmokers. OPG and OPN expressions were 100% negative to focal in the smoker group and 50% negative to focal and 50% weak/moderate in the nonsmoker group. TNF-α was 25% negative to focal and 75% weak/moderate in the smoker group and 33.33% negative to focal and 66.66% weak/moderate in the nonsmoker group. Quantitative analysis of the data using the Mann-Whitney U test showed that there was a significant difference in the immunoexpression of RANKL (P < .05), OPG (P < .05), and OPN (P < .05), but there was no statistical difference in the immunoexpression of TNF-α (P > .05) between the 2 groups.

CONCLUSIONS

These findings suggest that smoking is capable of altering the inflammatory response, influencing the evolution of CAP.

Immunoexpression of Interleukin 17, 6, and 1 Beta in Primary Chronic Apical Periodontitis in Smokers and Nonsmokers

INTRODUCTION

The purpose of this study was to compare the immunoexpression of biomarkers interleukin (IL)-17, IL-6, and IL-1β in primary chronic apical periodontitis in smokers and nonsmokers.

METHODS

Teeth with primary chronic apical periodontitis indicated for extraction in 16 cigarette smokers and 16 nonsmokers were selected. Silanized sections of tissue were used for immunohistochemical analysis after being stained with hematoxylin-eosin for histopathologic categorization. Subsequently, the images were analyzed with an optical microscope, and each slide was subdivided into 5 high-magnification fields, with scores (0-2) being assigned according to the amount of staining for each antibody.

RESULTS

The qualitative analysis of IL-17 cytokine expression showed no focal expression in 5.8%, weak to moderate expression in 17.6%, and strong expression in 76.4% of the smokers and no focal expression in 78.5% and weak to moderate expression in 21.4% of the nonsmokers. IL-6 expression was negative to focal in 13.3%, weak to moderate in 53.3%, and strong in 33.3% of the smokers and negative to focal in 33.3%, weak to moderate in 25%, and strong in 41.6% of the nonsmokers. IL-1β expression was weak to moderate in 87.5% and negative to focal expression in 12.5% of the smokers and negative to focal expression in 100% of the nonsmokers. Quantitative evaluation of the data using the Mann-Whitney U test showed a significant difference in the immunoexpression of IL-17 (P < .0001) and IL-1β (P < .0001) and no significant difference in the immunoexpression of IL-6 (P = .46) between the 2 groups (P < .05).

CONCLUSIONS

The cytokines IL-17 and IL-1β were more highly expressed in smokers than nonsmokers, whereas IL-6 expression was similar in the 2 groups.

Differentiated Immunohistochemical Expression of Osteoclastogenic Markers in Radicular Cyst, Odontogenic Keratocyst, and Ameloblastoma

The aim of this study was to investigate the osteoclastogenesis process by means of immunohistochemical markers for receptor activator of nuclear factor κB ligand (RANKL), osteoprotegerin (OPG), interleukin-6 (IL-6), and cathepsin K (CTSK) antigens in osteolytic lesions of maxillary bones. The sample consisted of 23 radicular cysts (RC), 25 odontogenic keratocysts (OKC), and 25 ameloblastomas (AM). RANKL was statistically higher in RC (49.6±15.2/53.7±18) and OKC (48.6±15.1/51.4±16.8) when compared with AM (37.2±12.5/36.4±13) in the epithelium and connective tissue. OPG was lower in OKC (34.8±18.5) only in connective tissue when compared with RC (44.5±11.2). The expression of RANKL was statistically higher than OPG in RC (epithelium and connective tissue) and OKC (connective tissue). For IL-6, a statistical difference was observed only in the connective tissue between groups, with higher expression in RC (48.2±15) and lower in OKC (22±11.9). The expression of IL-6 was correlated with the intensity of the inflammatory infiltrate. CTSK was statistically higher in AM (34±19) and OKC (29±13.8) compared with RC (19±10.5). According to the results of the present research the bone resorption in cysts and odontogenic tumors occurs through different mechanisms. The ostoclastogenic process in lesions with aggressive clinical behavior, as AM and OKC, seems to be associated with the expression of CTSK. In contrast, lesions with inflammatory etiology, as RC, the expression of IL-6 seems to have an important role in the bone resorption process. The highest expression of RANKL under the expression of OPG also seems to contribute to the growth mechanism of RC and OKC.

Expression of Inflammatory Markers RANK, MMP-9 and PTHrP in Chronic Apical Periodontitis from People Living with HIV Undergoing Antiretroviral Therapy

To compare the expression of the receptor activator of nuclear factor-kappa B (RANK), matrix metalloproteinase 9 (MMP-9) and parathyroid hormone-related protein (PTHrP) in primary chronic apical periodontitis lesions (CAPLs) between people living with HIV (PLWHIV) undergoing antiretroviral therapy (ART) and HIV- individuals, 32 CAPLs (16 lesions from each group) were submitted to histopathological and immunohistochemical analyses and compared between groups. The majority of the PLWHIV group had undetectable plasma viral loads (n = 13; 81.3%). The means of TCD4+ lymphocytes, exposure to HIV-1 and the time of the use of ART were 542.1 cells/mm³ (SD = 256.4), 6.3 years (SD = 2.9) and 5.0 years (SD = 2.5), respectively. Of all variables studied, only histopathological diagnosis showed a significant difference between groups (LWHIV: granuloma n = 11 (68.0%); cyst n = 5 (31.2%); HIV-: granuloma n = 15 (93.8%); cyst n = 1 (6.2%); p = 0.015). When comparing the expressions of the three inflammatory markers between the groups, no significant differences were seen. There was no difference in the expression of RANK, PTHrP and MMP-9 in primary chronic apical periodontitis lesions between PLWHIV under ART and HIV- individuals.

Macrophage phenotypes and Gas6/Axl signaling in apical lesions

Background/purpose

Macrophages participate in the periapical inflammation with pro-inflammatory M1 cells and anti-inflammatory M2 cells. Gas6/Axl signal is the responsible pathway for the activation of M1 and polarization of M2. The aim of this study was to compare the number of CD16⁺ M1 cells, CD206⁺ M2 cells, and Gas6/Axl expression between apical granulomas and radicular cysts.

Materials and methods

Twenty-four cases of granuloma and twenty of cysts were submitted to immunohistochemistry using anti-CD16 and anti-CD206 antibodies for determining M1 and M2 macrophages and investigating the cells with positive Gas6 and Axl expression.

Results

There were more numerous of M1 macrophages in radicular cysts (175.9 ± 87.7) compared to apical granuloma (116.6 ± 55.8), and M2 macrophages was higher in cysts (204.0 ± 97.6) than granuloma (152.9 ± 64.6). The level of Gas6/Axl expression were similar. There was a significant different in M1 macrophage (P = 0.014) between two diagnosis. In patients with or without root resorption, the number of M1 were 194.6 ± 57.2 compared with 139.1 ± 79.6. The number of M2 were 241.7 ± 81.4 and 164.6 ± 77.1. The expression of Axl was stronger in root resorption patients (191.1 ± 43.6), but the tendency in Gas6 expression was similar. Significant differences were noted in high M2 infiltration and Axl positive lesions.

Conclusion

It appears that macrophages associated with significantly higher numbers in radicular cysts than apical granuloma. Meanwhile, macrophages and Axl receptor was intensively expressed in patients with root resorption, related to severe inflammation.

Inflammatory profile of chronic apical periodontitis: a literature review

Apical periodontitis caused by root canal infection is the most frequent pathological lesion in the jaws, mainly manifested as periapical granulomas and cysts. Understanding of the formation and progression of apical periodontitis as well as the identification of inflammatory biomarkers can help increase the knowledge of pathogenic mechanisms, improve the diagnosis and provide support for different therapeutic strategies. The objective of the present article is to review inflammatory biomarkers such as cytokines, chemokines, inflammatory cells, neuropeptides, RANK/RANKL/OPG system and other inflammatory markers and to relate these systems to the development and progression of pathological conditions related to apical periodontitis.

Immunohistochemical and mRNA expression of RANK, RANKL, OPG, TLR2 and MyD88 during apical periodontitis progression in mice

Objective

To evaluate and correlate, in the same research, the mRNA expression and the staining of RANK, RANKL, OPG, TLR2 and MyD88 by immunohistochemistry in the apical periodontitis (AP) progression in mice.

Material and Methods

AP was induced in the lower first molars of thirty-five C57BL/6 mice. They were assigned to four groups according to their euthanasia periods (G0, G7, G21 and G42). The jaws were removed and subjected to histotechnical processing, immunohistochemistry and real-time reverse transcription-PCR (qRT-PCR). Data were analyzed with parametric and nonparametric tests (α=0.05).

Results

An increase of positive immunoreactivity for RANK, RANKL, OPG, TLR2 and MyD88 was observed over time (p<0.05). The RANKL expression was different between the groups G0 and G42, G21 and G42 (p=0.006), with G42 presenting the higher expression in both comparations. The OPG expression was statistically different between the groups G0 and G7, G7 and G21 and G7 and G42 (p<0.001), with G7 presenting higher expression in all the time points. The TLR2 expression was different between the groups G0 and G42 (p=0.03), with G42 showing the higher expression. The MyD88 expression presented a statistical significant difference between groups G7, G21 and G42 compared with G0 (p=0.01), with G0 presenting the smallest expression in all the comparisons. The Tnfrsf11/Tnfrsf11b (RANKL/OPG) ratio increased with the AP progression (p=0.002). A moderate positive correlation between MyD88 and RANKL (r=0.42; p=0.03) and between MyD88 and TLR2 (r=0.48; p<0.0001) was observed.

Conclusion

The expression of the RANK, RANKL, OPG, MyD88 and TLR2 proteins as well as the ratio Tnfrsf11/Tnfrsf11b (RANKL/OPG) increased with AP progression. There was also a moderate positive correlation between the expression Myd88-Tnfrsf11 and Tlr2-Myd88, suggesting the relevance of Tlr2-Myd88 in bone loss due to bacterial infection.

Pro-inflammatory and anti-inflammatory cytokine expression in post-treatment apical periodontitis

OBJECTIVE

This study evaluated the expression of pro-inflammatory (IL-1β, IL-6, IFN-γ and TNF-α) and anti-inflammatory (IL-4 and TGF-β) cytokines in apical periodontitis lesions. Correlations between these cytokines and clinical and cone-beam computed tomographic (CBCT) data were also assessed.

MATERIAL AND METHODS

Apical periodontitis lesions' data were obtained from 27 patients subjected to periradicular surgery. Specimens were processed for histopathologic and immunohistochemical analysis. Sections were evaluated according to the amount of positive staining for each antibody. Expression levels of the target mediators were compared with clinical and CBCT data.

RESULTS

Twenty lesions were diagnosed as granuloma and 7 as cyst. In granulomas, IL-4 expression was significantly higher than IL-6 (p=0.001) and TNF-α (p=0.001). There was a significant relationship between high levels of TNF-α and lesions <5 mm (p=0.017). In cysts, IL-6 expression was significant lower than IL-4 (p=0.001) and IFN-γ (p=0.004). There was a significant relationship between high levels of TGF-β and endodontic treatment performed ≤4 years before (p=0.045). In general, IL-4 was the most expressed mediator in both cysts and granulomas.

CONCLUSIONS

There was a balance between the expression of pro-inflammatory and anti-inflammatory cytokines associated with the chronic periradicular inflammatory process. TNF-α and TGF-β were related to some clinical and CBCT data.

Participation of osteoclastogenic factors in immunopathogenesis of human chronic periapical lesions

BACKGROUND

Chronic periapical lesions (CPLs) are common lesions of the oral cavity and are the result of caries, tooth fracture, iatrogenic causes, or factors causing contamination and pulp necrosis. Inflammatory cells participate in the expansion of CPLs by releasing factors that stimulate or inhibit osteolytic activity. The objective of this study was to investigate the participation of RANKL, TNF-α, cathepsin K, IL-33, and OPG in the development of radicular cysts (RCs) and periapical granulomas (PGs).

METHODS

Paraffin-embedded sections of 30 RCs and 22 PGs were submitted to immunohistochemistry.

RESULTS

Immunoexpression of the proteins studied was observed in the epithelium and capsule of RCs, as well as in connective tissue of PGs. The expression of the osteoclastogenic factors studied differed significantly in RCs and PGs (P < .001), with lower expression of OPG in RCs. In PGs, the lowest expression was observed for cathepsin K. Comparison of the 2 lesions showed a similar participation of RANKL and IL33, while a significant difference was observed for OPG (P < .001), TNF-α (P = .002), and cathepsin K (P = .016). No association of the expression of the proteins with lesions size was observed.

CONCLUSIONS

This study demonstrated the participation of RANKL, TNF-α, IL-33, cathepsin K, and OPG in the development of RCs and PGs, with emphasis on the highest immunoreactivity of cathepsin in RCs and TNF-α and OPG in PGs. OPG possibly determines the slower growth of PGs compared to RCs.