Distribution of mast cells and macrophages and expression of interleukin-6 in periapical cysts

Is there any association between the presence of biomarkers and apical periodontitis? A systematic review

This systematic review aimed to verify whether there is evidence of an association between apical periodontitis and the presence of systemic biomarkers. This study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses - PRISMA. For this, the acronym PECO was used; population (P) of adult humans exposed (E) to the presence of apical periodontitis, compared (C) to adult humans without apical periodontitis, and the outcome (O) of the presence of biomarkers was observed. The articles were searched in PubMed, Scopus, Web of Science, LILACS, Cochrane Library, OpenGray, and Google Scholar grey databases. Subsequently, studies were excluded based on title, abstract, and full article reading, following the eligibility criteria. The methodological quality of the selected studies was evaluated using the Newcastle-Ottawa qualifier. After exclusion, 656 studies were identified, resulting in 17 final articles that were divided into case-control, cross-sectional, and cohort studies. Eight studies were considered to have a low risk of bias, one had a medium risk of bias, and eight had a high risk of bias. In addition, 12 articles evaluated biomarkers in blood plasma, four evaluated them in saliva, and only one evaluated them in gingival crevicular fluid. The results of these studies indicated an association between apical periodontitis and the systemic presence of biomarkers. These markers are mainly related to inflammation, such as interleukins IL-1, IL-2, and IL-6, oxidative markers, such as nitric oxide and superoxide anions, and immunoglobulins IgG and IgM.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier (CRD42023493959).

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.

Effect of Lipopolysaccharide-Induced Apical Periodontitis in Diabetes Mellitus Rats on Periapical Inflammation

OBJECTIVES

 To evaluate periapical inflammation through immunohistochemical analysis of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-a) expression resulting from lipopolysaccharide (LPS)-induced apical periodontitis in diabetes mellitus rats, observed at 14, 28, and 42 days.

MATERIALS AND METHODS

 Diabetes model on rats was induced by streptozotocin (STZ). Fifteen rats were injected with low-dose STZ for 5 days and waited for 5 days until the blood glucose level was stable and measured above 300 mg/dL confirmed by a digital glucometer. LPS was used to induce apical periodontitis. After performing access cavity, pulpal and root canal extirpation was done on the right mandibular first molar's root canal space of rats, under anesthesia. LPS of 1 mg/mL dose was induced in the pulpal and root canal space. Apical periodontitis was expected 14 days afterward and then, the rats were randomly allocated to three groups. The first group was terminated 14 days after induction and used as control. The second group was observed 28 days after induction, and the third group was observed 42 days after induction. IL-6 and TNF-a expression was analyzed by immunohistochemistry on macrophages in the periapical area.

STATISTICAL ANALYSIS

 Data were analyzed using one-way ANOVA and continued with the post hoc Tukey HSD test. Significance was considered if p < 0.05.

RESULTS

 LPS induced apical periodontitis in diabetes mellitus rats at control (14 days), 28 and 42 days observation showed a significant increase in the expression of IL-6 and TNF-a. There were significant differences between the control and observed groups (p < 0.05). The expression of IL-6 in the apical area was not significant at 14 and 28 days (p > 0.05) but increased significantly at 42 days (p < 0.05). The expression of TNF-a in the apical area was significantly increased after 14 days (p < 0.05) and remained stable at 28 and 42 days (p > 0.05).

CONCLUSIONS

 The periapical inflammation of LPS-induced apical periodontitis in diabetes mellitus rats increased macrophages' expression of IL-6 at 42 days and TNF-a at 28 days.

CRISPR/Cas13d targeting GZMA in PARs pathway regulates the function of osteoclasts in chronic apical periodontitis

Chronic apical periodontitis is a prevalent oral disease characterized by bone loss, and its underlying mechanisms remain unclear. This study aimed to investigate the role and mechanism of the serine protease GZMA in osteoclasts during chronic apical periodontitis. To address this, we employed crRNA/Cas13d to inhibit GZMA expression and examined its impact on osteoclast behavior. Our findings revealed that GZMA plays a significant role in promoting osteoclast cell proliferation while inhibiting cell apoptosis. Additionally, the inhibition of GZMA led to a notable increase in miR-25-3p expression, which, in turn, downregulated the expression of TGF-β. Consequently, the reduction in TGF-β expression led to a decrease in PAR1 expression within the PARs pathway. These results suggest that GZMA might serve as a promising therapeutic target for the treatment of chronic apical periodontitis. Furthermore, our study highlights the potential of targeting GZMA using crRNA/Cas13d as a valuable approach for future therapeutic interventions.

Five-year outcomes of immediate implant placement for mandibular molars with and without chronic apical periodontitis: A retrospective study

BACKGROUND

Most physicians consider molars with chronic apical periodontitis (CAP) lesions as contraindications for immediate implant placement. At the patient’s request, we perform immediate implant placement of the mandibular molars with CAP in clinical practice.

AIM

To retrospectively analyze and compare the 5-year outcomes of immediate implant placement of the mandibular molars with CAP and those without obvious inflammation.

METHODS

The clinical data of patients with immediate implant placement of the mandibular molars in the Department of Oral and Maxillofacial Surgery, the Affiliated Hospital of Qingdao University, from June 2015 to June 2017 were collected. The patients were divided into CAP (n = 52) and no-CAP (n = 45) groups. Changes in bone mineral density and bone mass around implants were analyzed 5 years after implant restoration.

RESULTS

At 5 years after implantation, the peri-implant bone mineral density was 528.2 ± 78.8 Hounsfield unit (HU) in the CAP group and 562.6 ± 82.9 HU in the no-CAP group (P = 0.126). Marginal bone resorption around implants did not differ significantly between the two groups, including buccal (P = 0.268) or lingual (P = 0.526) resorption in the vertical direction or buccal (P = 0.428) or lingual (P = 0.560) resorption in the horizontal direction. Changes in the peri-implant jump space did not differ significantly between the two groups, including the buccal (P = 0.247) or lingual (P = 0.604) space in the vertical direction or buccal (P = 0.527) or lingual (P = 0.707) space in the horizontal direction. The gray value of cone-beam computed tomography measured using Image J software can reflect the bone mineral density. In the CAP area, the gray values of the bone tissue immediately and 5 years after implant placement differed significantly from those of the surrounding bone tissue (P < 0.01).

CONCLUSION

The results of this study suggest that immediate implant placement of the mandibular molars with CAP can achieve satisfactory 5-year clinical results, without significant differences in the complications, survival rate, or bone tissue condition from the no-CAP mandibular molars.

Five-year outcomes of immediate implant placement for mandibular molars with and without chronic apical periodontitis: A retrospective study

BACKGROUND

Most physicians consider molars with chronic apical periodontitis (CAP) lesions as contraindications for immediate implant placement. At the patient's request, we perform immediate implant placement of the mandibular molars with CAP in clinical practice.

AIM

To retrospectively analyze and compare the 5-year outcomes of immediate implant placement of the mandibular molars with CAP and those without obvious inflammation.

METHODS

The clinical data of patients with immediate implant placement of the mandibular molars in the Department of Oral and Maxillofacial Surgery, the Affiliated Hospital of Qingdao University, from June 2015 to June 2017 were collected. The patients were divided into CAP (n = 52) and no-CAP (n = 45) groups. Changes in bone mineral density and bone mass around implants were analyzed 5 years after implant restoration.

RESULTS

At 5 years after implantation, the peri-implant bone mineral density was 528.2 ± 78.8 Hounsfield unit (HU) in the CAP group and 562.6 ± 82.9 HU in the no-CAP group (P = 0.126). Marginal bone resorption around implants did not differ significantly between the two groups, including buccal (P = 0.268) or lingual (P = 0.526) resorption in the vertical direction or buccal (P = 0.428) or lingual (P = 0.560) resorption in the horizontal direction. Changes in the peri-implant jump space did not differ significantly between the two groups, including the buccal (P = 0.247) or lingual (P = 0.604) space in the vertical direction or buccal (P = 0.527) or lingual (P = 0.707) space in the horizontal direction. The gray value of cone-beam computed tomography measured using Image J software can reflect the bone mineral density. In the CAP area, the gray values of the bone tissue immediately and 5 years after implant placement differed significantly from those of the surrounding bone tissue (P < 0.01).

CONCLUSION

The results of this study suggest that immediate implant placement of the mandibular molars with CAP can achieve satisfactory 5-year clinical results, without significant differences in the complications, survival rate, or bone tissue condition from the no-CAP mandibular molars.

Creating an atlas of the bone microenvironment during oral inflammatory-related bone disease using single-cell profiling

Oral inflammatory diseases such as apical periodontitis are common bacterial infectious diseases that may affect the periapical alveolar bone tissues. A protective process occurs simultaneously with the inflammatory tissue destruction, in which mesenchymal stem cells (MSCs) play a primary role. However, a systematic and precise description of the cellular and molecular composition of the microenvironment of bone affected by inflammation is lacking. In this study, we created a single-cell atlas of cell populations that compose alveolar bone in healthy and inflammatory disease states. We investigated changes in expression frequency and patterns related to apical periodontitis, as well as the interactions between MSCs and immunocytes. Our results highlight an enhanced self-supporting network and osteogenic potential within MSCs during apical periodontitis-associated inflammation. MSCs not only differentiated toward osteoblast lineage cells but also expressed higher levels of osteogenic-related markers, including Sparc and Col1a1. This was confirmed by lineage tracing in transgenic mouse models and human samples from oral inflammatory-related alveolar bone lesions. In summary, the current study provides an in-depth description of the microenvironment of MSCs and immunocytes in both healthy and disease states. We also identified key apical periodontitis-associated MSC subclusters and their biomarkers, which could further our understanding of the protective process and the underlying mechanisms of oral inflammatory-related bone disease. Taken together, these results enhance our understanding of heterogeneity and cellular interactions of alveolar bone cells under pathogenic and inflammatory conditions. We provide these data as a tool for investigators not only to better appreciate the repertoire of progenitors that are stress responsive but importantly to help design new therapeutic targets to restore bone lesions caused by apical periodontitis and other inflammatory-related bone diseases.

Plasma Rich in Growth Factors in the Treatment of Endodontic Periapical Lesions in Adult Patients: 3-Dimensional Analysis Using Cone-Beam Computed Tomography on the Outcomes of Non-Surgical Endodontic Treatment Using A-PRF+ and Calcium Hydroxide: A Retrospective Cohort Study

The study presents results of periapical lesion healing after one-visit root canal treatment (RCT) with Advanced Platelet Rich Fibrin plus (A-PRF+) application compared to a two-visit RCT with an inter-appointment calcium hydroxide filling. The comparison was made based on CBCT-Periapical Index (PAI) lesion volume changes and the occurrence of post endodontic pain. The results of 3D radiographic healing assessments based on volume reduction criteria were different from the CBCT-PAI. Based on volume changes, the healing assessment criteria-9 cases from the Study Group and six cases in the Control Group were defined as healed. Based on the CBCT-PAI healing assessment criteria, 8 cases from the Study Group and 9 cases from the Control Group were categorized as healed. The volumes of apical radiolucency were, on average, reduced by 85.93% in the Study Group and by 72.31% in the Control Group. Post-endodontic pain occurred more frequently in the Control than in the Study Group. The highest score of pain in the Study Group was five (moderate pain, n = 1), while in the Control Group, the highest score was eight (severe pain, n = 2). In the 6-month follow-up, CBCT scans showed a better healing tendency for patients in the Study Group.

Macrophages in periapical lesions: Potential roles and future directions

Periapical lesions are infectious diseases that occur in the apical region of teeth. They result in the destruction of alveolar bone and are usually accompanied by swelling, pain, and possible systemic impacts. A complex interaction between pathogens and the host immune system determines the development, progression, and outcome of periapical lesions. The lesions, if not treated promptly, may cause resorption of bone tissue, destruction of the periodontal ligament, and loss of the affected teeth, all of which can severely worsen the quality of life of patients, often at considerable economic cost to both patients and medical organizations. Macrophages are a group of heterogeneous cells that have many roles in the development of infections, destruction and reconstruction of bone tissues, and microbe–host interactions. However, the differential and comprehensive polarization of macrophages complicates the understanding of the regulatory mechanism of periapical lesion progression. This report provides a comprehensive review of recent advances in our knowledge of the potential role of macrophages in determining the turnover of human periapical lesions. For example, macrophage differentiation might indicate whether the lesions are stable or progressing while the extent of bacteria invasion could regulate the differentiation and function of macrophages involved in the periapical lesion. In addition, alternative strategies for the treatment of apical periodontitis are discussed.

Ex vivo study of IL-6 expression and function in immune cell subsets from human periapical lesions

AIM

Even though IL-6 is a key inflammatory cytokine in periapical lesions (PLs), its function in stable periapical disease is unknown. Therefore, the aim of this study was to investigate following: first, the ex vivo production of IL-6 by clinically different PLs; next, subsets of immune cells expressing IL-6 in PLs according to their inflammatory status and finally, modulatory effect of IL-6 on T-cell cytokine production in cell cultures.

METHODOLOGY

Inflammatory cells were isolated from a total of 95 human PLs. Detection of IL-6⁺ cells within the myeloid and lymphoid populations was performed by multicolour flow cytometry. ELISA and FlowCytomix Microbeads Assay were used to measure cytokine levels in culture supernatants. To study the role of IL-6 in PLs, mononuclear cells (MNC) from symptomatic (Sy) or asymptomatic (Asy) PLs were treated with IL-6 or Tocilizumab, an IL-6R blocking antibody. The differences between groups were tested by unpaired t-test, Mann-Whitney or Friedman tests.

RESULTS

The levels of IL-6 in PL MNC culture supernatants were significantly higher compared to total PL cells and PL granulocytes (p<0.001). MNC from Sy PLs produced significantly hihger levels of IL-6 than MNC from Asy PLs (p<0.001). Flow cytometry analysis showed that NKT cells, CD8⁺ T cells and M2 macrophages (MØ), were dominant IL-6⁺ cells, in contrast to CD4⁺ T cells. However, CD8⁺ and CD4⁺ T cells contributed the most to IL-6 production. IL-6^hi producing MNC cultures had higher levels of Th1 (IFN-γ), Th17 (IL-17A), Tfh (IL-21) and RANKL, whereas Th2 (IL-4) and Tregs cytokines (IL-10, TGF-β) were lower, compared to IL-6^low producing cultures. Exogenous IL-6 stimulated 17A, IL-21 and RANKL, independently of PL activation status, but decreased IFN-γ, IL-4 and IL-33 levels in IL-6^hi producing cultures. Tocilizumab increased IL-10 and TGF-β in IL-6^low producing cultures. All differences were p<0.05.

CONCLUSIONS

Most immune cells from Sy PLs expressed higher levels of IL-6 compared to Asy PLs, which correlated with IL-6 production in culture. Analysis of cytokines suggested a dominant pro-inflammatory T-cell response and osteodestructive function of IL-6 in PLs judging by Th17/Tfh cell activation, Tregs inhibition and increased RANKL/OPG ratio. Excessive IL-6 production decreased Th1/Th2 responses.

Expression of epithelial growth factors and of apoptosis-regulating proteins, and presence of CD57+ cells in the development of inflammatory periapical lesions

The mechanisms that stimulate the proliferation of epithelial cells in inflammatory periapical lesions are not completely understood and the literature suggests that changes in the balance between apoptosis and immunity regulation appear to influence this process.

Serum levels of inflammatory markers and HbA1c in patients with type 2 diabetes and apical periodontitis: Preliminary findings

This pilot study assessed the glycaemic control and the serum levels of inflammatory mediators in type 2 diabetes (T2DM) patients with apical periodontitis (AP). Thirty individuals were divided into four groups: Healthy (H); with AP (AP); with T2DM (T2DM); and with T2DM and AP (T2DM-AP). Demographic and pharmacological data were registered. The body mass index (BMI) and the levels of glycated haemoglobin (HbA1c) and IL-1β, IL-6, IL-10, CCL3 and CCL4 were evaluated. AP areas were determined radiographically. Mean age was 64 ± 12 years, with 63% females. Most T2DM patients were under treatment with metformin and antihypertensives. BMI and H1bAc were significantly higher in T2DM patients in relation to H and AP groups. The AP areas were larger in the T2DM-AP group, compared with the AP group. These preliminary findings suggest no influence of AP on glycaemic control or inflammatory levels amongst T2DM patients, although T2DM increased the AP severity.

Langerhans Cells Correlate With Macrophages for Defense Mechanisms in the Atrophic Epithelium of Radicular Cysts

Langerhans cells (LCs) play important roles in cell-mediated immune reactions, as well as in the pathogenesis of periapical lesions. The aim of this study is to evaluate the role of LCs in the proliferative epithelium of radicular cysts (RCs) and the release of the proinflammatory cytokine tumor necrosis factor α (TNF-α) associated with epithelial thickness. Thirty cases of RCs and 30 cases of residual RCs were randomly selected. Morphologic analysis was performed to evaluate the association between the inflammatory infiltrate, cystic epithelial thickness and lesion size, in addition to immunohistochemical assessment of CD1a, CD68, and TNF-α. The highest macrophage percentages and TNF-α scores were found in RCs (P=0.038 and 0.017, respectively). The largest number of LCs was observed in RCs (P=0.021), especially those exhibiting atrophic epithelium (P=0.05). In addition, LCs were positively correlated with the number of macrophages in both RCs and residual RCs (P=0.033 and 0.002, respectively). In contrast to LCs, the largest number of macrophages was detected in cases with an intense inflammatory infiltrate (P=0.022). In addition, the highest TNF-α scores were associated with an intense inflammatory infiltrate (P=0.024) when analyzed in the capsule of RCs (P=0.017). In conclusion, LCs participate in defense mechanisms and were present in all cases evaluated. Along with macrophages, these cells release proinflammatory cytokines such as TNF-α, which is responsible for inducing the continued proliferation of cystic epithelium.

Localization of interleukin-6 signaling complex in epithelialized apical lesions of endodontic origin

OBJECTIVES

We aimed to determine the immunolocalization patterns of the interleukin (IL)-6 signaling complex in epithelialized and non-epithelialized apical lesions of endodontic origin (ALEOs).

MATERIALS AND METHODS

Epithelialized (n = 8) and non-epithelialized (n = 7) ALEOs were obtained from teeth with indication of extraction in patients with clinical diagnosis of apical periodontitis. All tissues were subjected to routine processing for histopathologic examination and primary antibodies for IL-6, IL-6 receptor (R), and glycoprotein (gp)-130 were used for immunohistochemistry and double immunofluorescence co-localization.

RESULTS

IL-6, IL-6R, and gp-130 were immunolocalized in endothelial cells and mononuclear leukocytes in a diffuse pattern within the connective tissue of epithelialized and non-epithelialized ALEOs. In the epithelialized lesions, two different patterns were identified: IL-6 signaling complex was localized within the proliferating epithelium in a diffuse intracellular pattern and in a cell membrane localization pattern within the mature epithelial lining, showing a decreased intensity towards the surface layers.

CONCLUSIONS

IL-6, IL-6R, and gp-130 localized to mononuclear inflammatory cells, vascular endothelial cells, and immature proliferating epithelia in a diffuse pattern and in mature lining epithelia in a localized cell membrane pattern, supporting a role for epithelial proliferation during cyst formation. Additional cell membrane co-localization of IL-6 receptor complex suggests classic signaling involvement in addition to trans-signaling.

Involvement of tryptase-positive mast cells and angiogenesis in the growth of inflammatory odontogenic cysts

Inflammatory periapical lesions are characterized by infiltration of different immune cell types, the functions of which depend on an effective vascular network. This study aimed to evaluate the mast cells density (MCD) in inflamatory odontogenic cysts capsules concerning microvascular density (MVD), microvascular area (MVA), and microvascular perimeter (MVP), and correlate such findings with the type of lesion, intensity of the inflammatory infiltrate, and thickness of the epithelial lining. Twenty inflamatory dentigerous cysts (IDCs), twenty radicular cysts (RCs), and twenty residual radicular cysts (RRCs) were submitted to immunohistochemical analysis using anti-tryptase and anti-CD34 antibodies. RCs exhibited the highest MCD, MVD, MVA, and MVP indexes (p = < 0.001, p = 0.008, p = 0.003 and p = < 0.001, respectively), and lesions with inflammatory infiltrate grade III showed the highest MVD (p = 0.044). Considering epithelial thickness, a higher MVP index was identified in lesions with hyperplastic epithelium (p = 0.018). In IDCs, RCs, and RRCs, a strong positive correlation was observed between MVA and MVP (r = 0.950 and p = < 0.001; r = 0.914 and p = < 0.001; r = 0.713 and p = < 0.001, respectively). In IDCs, a moderate correlation was observed between MCD and both MVA and MVP (r = 0.660 and p = 0.002; r = 0.634 and p = 0.003, respectively). These results suggest that tryptase-positive mast cells might play an important role in the angiogenic activity of IDCs, while RCs had the highest indexes. Our findings also confirmed that the intensity of the inflammatory infiltrate and epithelial thickness influence angiogenesis.

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.

Differentiation of periapical granuloma from radicular cyst using cone beam computed tomography images texture analysis

Objective

This study aimed to investigate the use of texture analysis for characterization of radicular cysts and periapical granulomas and to assess its efficacy to differentiate between both lesions with histological diagnosis.

Methods

Cone beam computed tomography (CBCT) images were obtained from 19 patients with 25 periapical lesions (14 radicular cysts and 11 periapical granulomas) confirmed by biopsy. Regions of interest were created in the lesions from which 11 texture parameters were calculated. Spearman's correlation analysis was performed and adjusted with Benjamini-Hochberg false discovery rate procedure (FDR <0.005).

Results

The texture parameters used to differentiate the lesions were assessed by using a receiver operating characteristic analysis. Five texture parameters were predictive of lesion differentiation for eight positions: angular second moment; sum of squares; sum of average; contrast; correlation.

Conclusion

Texture analysis of CBCT scans distinguishes radicular cysts from periapical granulomas and can be a promising diagnostic tool for periapical lesions.

Clinical significance

Texture analysis can be used in diagnostic and treatment monitoring to provide supplementary information.

Presence of langerhans cells, regulatory T cells (Treg) and mast cells in asymptomatic apical periodontitis

Asymptomatic Apical Periodontitis is essentially an inflammatory disease of microbial aetiology. Association and function of the cell components involved, or specific inductive factors and growth mediators associated with development, maintenance and resolution of the periapical lesions are still unknown. The objective of this study was to evaluate the concentration of Regulatory T cells (FoxP3+; Treg), Langerhans cells (CD1a+; LC) and mast cells in asymptomatic apical periodontitis. 73 cases were selected: 30 periapical granulomas, 29 radicular cysts and 14 residual cysts. All groups were submitted to morphological analysis for classification of inflammatory infiltrate and thickness of the epithelial lining as well as to immunohistochemical analysis for detection of LC and Treg cells. Toluidine blue staining was used for detecting mast cells. Analysis showed higher mean numbers of LC (8.2 cells/0.2mm2), and Treg cells in radicular cysts (5.910 cells/0.2mm2). As for mast cells, it was found that radicular cysts had a higher mean number of these cells compared to other periapical lesions (12.68 cells/0.2mm2). The association between thickness of the epithelial lining and inflammatory cells showed that the presence of hypertrophic epithelium in radicular cysts presented higher density of LC. The number of LC and Treg cells play an important role in the control of the inflammatory micro-environment in periapical granulomas and radicular cysts, respectively. The presence of mast cells in radicular cysts may be associated with progression of the lesion. Knowledge regarding the inflammatory cell profile is therefore essential for a better understanding of the pathogenesis of asymptomatic periapical periodontitis.

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.

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.

Distribution of macrophages and plasma cells in apical periodontitis and their relationship with clinical and image data

BACKGROUND

Macrophages and plasma cells play a key role in the regulation of innate and adaptive immunity. The aim of this study was to assess the presence of these cells in apical periodontitis and their distribution comparing with clinical and image data.

MATERIAL AND METHODS

Thirty-three lesions were selected and divided in two groups (17 periapical cysts and 16 periapical granulomas). Immunoreactions using anti-CD68 and anti-CD138 antibodies were carried out; image analysis was performed with an optical microscope and 5 high-power fields from each slide were evaluated leading to an average score of immunoexpression. This mean score was compared between the two groups and correlated with the clinical and image data.

RESULTS

There was no statistically significant difference (p >0.05) for the mean average score of CD68+ macrophages and CD138+ plasma cells when comparing the two groups (cysts x granulomas) and the specimens included in each specific group. No statistically significant differences (p >0.05) were also observed when comparing the average scores with clinical and image data.

CONCLUSIONS

The presence of CD68+ macrophages and CD138+ plasma cells was similar in periapical cysts and granulomas and the presence of these cells did not correlate with clinical and image data from both groups. Key words:Macrophages, plasma cells, apical periodontitis, periapical granuloma, periapical cyst.

Aging effects in the expression of macrophages in post-treatment apical periodontitis lesions

OBJECTIVES

To evaluate the CD68 immunoexpression in post-treatment apical periodontitis lesions of older patients and compare them with lesions of younger/middle age adults.

METHODS

Biopsy specimens from 21 apical periodontitis lesions (12 granulomas and 9 cysts) were selected from older patients and 25 apical periodontitis lesions from younger/middle age adults (12 cysts and 13 granulomas) were selected and analyzed by immunohistochemistry using silanized slides with anti-CD68 antibody. The slides were subdivided in five high-power fields and the images were observed under an optical microscope to evaluate the epithelial and connective tissues.

RESULTS

The results showed that there was no statistical difference for the CD68 expression in epithelial tissue of cysts between younger/middle age adults and older patients. However, for the connective tissue of both cysts and granulomas, there was a statistical difference between the two age groups. There was a statistical difference between the epithelial and the connective tissues in cysts of younger/middle age adults, and also when the epithelial tissue of the cysts was compared with connective tissue of the granuloma. In the group of older patients, there was no statistical difference between the connective tissue of the cysts and granulomas.

CONCLUSION

The intensity of the macrophage staining was greater in the connective tissue of cysts and granulomas alike in the younger/middle age adult patients, suggesting that these cells participate actively in this tissue. Immune responses in older patients may be compromised, suggesting that there is a greater tendency for the endodontic treatment of these patients to fail.

M2 macrophages coexist with a Th1-driven profile in periapical cysts

AIM

To evaluate the participation of both Th1 and Th2 responses in periapical cysts by assessing the presence of M2 macrophages, as well as acute IL-1 β, TNF-α and IL-6 cytokines.

METHODOLOGY

Twenty-four cases of periapical cysts were selected. Immuno-expressions of IL-1 β, IL-6, TNF-α and CD163 were analysed in the cystic capsules in both superficial and deeper regions. Data were analysed with paired Wilcoxon test and Spearman correlation coefficient (P ≤ 0.05).

RESULTS

There was a higher expression of IL-1β, IL-6, TNF-α and M2 macrophages in the superficial region (P < 0.001) of cystic capsules. All acute cytokines had significant positive correlations amongst them regardless of the cystic capsule region. Regarding CD163, positive correlations occurred only with TNF-α (P = 0.007; r = 0.537) and IL-6 (P = 0.018; r = 0.478) in the superficial regions of the cystic capsule.

CONCLUSIONS

M2 macrophages participated actively in the inflammatory response of periapical cysts and correlated with the expression of certain acute Th1-related cytokines. This illustrates the coexistence of an acute and chronic Th2-driven immune response in these lesions. Although M2 macrophages favour the healing process, their presence is not sufficient for periapical cyst regression, once an acute active response has occurred due to an infectious stimuli.

Influence of surgical decompression on the expression of inflammatory and tissue repair biomarkers in periapical cysts

OBJECTIVE

The biologic effects of surgical decompression on the epithelium and connective tissues of periapical cysts are not fully understood. The aim of this study was to evaluate the expression of tissue repair and inflammatory biomarkers in periapical cysts before and after surgical decompression.

STUDY DESIGN

Nine specimens of periapical cysts treated with decompression before undergoing complete enucleation were immunohistochemically analyzed to investigate the expression of interleukin-1β, tumor necrosis factor-α, transforming growth factor-β1, matrix metalloproteinase-9, Ki-67, and epidermal growth factor receptor. Expression of the biomarkers was classified as positive, focal, or negative. Ki-67 immunoexpression was calculated as a cell proliferation index. The expression of the biomarkers was compared in the specimens from decompression and from the final surgical procedure.

RESULTS

Computed tomography demonstrated that volume was reduced in all cysts after decompression. There were no differences in the immunoexpression of the proinflammatory and tissue repair biomarkers when comparing the specimens obtained before and after the decompression.

CONCLUSIONS

Surgical decompression was efficient in reducing the volume of periapical cysts before complete enucleation. When comparing the specimens obtained from surgical decompression and from complete surgical removal, the immunohistochemical analysis did not show a decrease in proinflammatory biomarkers; neither did it show an increase in tissue repair biomarkers.

Modulation of Matrix Metalloproteinase 14, Tissue Inhibitor of Metalloproteinase 3, Tissue Inhibitor of Metalloproteinase 4, and Inducible Nitric Oxide Synthase in the Development of Periapical Lesions

INTRODUCTION

Periapical cysts and granulomas are chronic lesions caused by an inflammatory immune response against microbial challenge in the root canal. Different cell types, cytokines, and molecules have been associated with periapical lesion formation and expansion. Therefore, because of the chronic inflammatory state of these lesions, the aim of this study was to evaluate the in situ expression of matrix metalloproteinase (MMP)-14 and -19, tissue inhibitor of metalloproteinase (TIMP)-3 and -4, CD68, and inducible nitric oxide synthase (iNOS) in periapical cysts and granulomas.

METHODS

Sixteen cases of periapical cysts and 15 cases of periapical granulomas were analyzed. Ten normal dental pulps were used as the negative control. Immunohistochemistry was performed with anti-MMP-19, anti-MMP-14, anti-TIMP-3, anti-TIMP-4, anti-iNOS, and anti-CD68 antibodies.

RESULTS

The expression of TIMP-3, TIMP-4, iNOS, and CD68 was significantly higher in both the cyst and granuloma groups than in the control group. TIMP-4 was also significantly higher in cases of chronic apical abscess. There was also a significant difference in the expression of MMP-14 between the cyst and control groups. However, there were no differences in the expression of MMP-19 between the 3 groups.

CONCLUSIONS

Our data suggest that the expression of MMP-14, TIMP-3, and TIMP-4 is associated with the development of periapical lesions.

Macrophage polarization differs between apical granulomas, radicular cysts, and dentigerous cysts

OBJECTIVES

Apical periodontitis can appear clinically as apical granulomas or radicular cysts. There is evidence that immunologic factors are involved in the pathogenesis of both pathologies. In contrast to radicular cysts, the dentigerous cysts have a developmental origin. Macrophage polarization (M1 vs M2) is a main regulator of tissue homeostasis and differentiation. There are no studies comparing macrophage polarization in apical granulomas, radicular cysts, and dentigerous cysts.

MATERIALS AND METHODS

Forty-one apical granulomas, 23 radicular cysts, and 23 dentigerous cysts were analyzed in this study. A tissue microarray (TMA) of the 87 consecutive specimens was created, and CD68-, CD11c-, CD163-, and MRC1-positive macrophages were detected by immunohistochemical methods. TMAs were digitized, and the expression of macrophage markers was quantitatively assessed.

RESULTS

Radicular cysts are characterized by M1 polarization of macrophages while apical granulomas show a significantly higher degree of M2 polarization. Dentigerous cysts have a significantly lower M1 polarization than both analyzed periapical lesions (apical granulomas and radicular cysts) and accordingly, a significantly higher M2 polarization than radicular cysts. Macrophage cell density in dentigerous cysts is significantly lower than in the periapical lesions.

CONCLUSIONS

The development of apical periodontitis towards apical granulomas or radicular cysts might be directed by macrophage polarization. Radicular cyst formation is associated with an increased M1 polarization of infiltrating macrophages. In contrast to radicular cysts, dentigerous cysts are characterized by a low macrophage infiltration and a high degree of M2 polarization, possibly reflecting their developmental rather than inflammatory origin.

CLINICAL RELEVANCE

As M1 polarization of macrophages is triggered by bacterial antigens, these results underline the need for sufficient bacterial clearance during endodontic treatment to prevent a possible M1 macrophage-derived stimulus for radicular cyst formation.

Cellular Profile and Expression of Immunologic Markers in Chronic Apical Periodontitis from HIV-infected Patients Undergoing Highly Active Antiretroviral Therapy

INTRODUCTION

This study tested the hypothesis that the inflammatory cell profile (CD3-, CD4-, CD8-, CD20-, and CD68-positive cells) and the expression of immunologic markers (tumor necrosis factor α, interferon-γ, interleukin-6, and interleukin-18) in chronic apical periodontitis are the same between non-HIV-infected patients and HIV-infected patients undergoing highly active antiretroviral therapy (HAART).

METHODS

Thirty-four surgically excised chronic apical periodontitis lesions were sampled from 34 patients (17 HIV-infected and 17 non-HIV-infected). The lesions were extracted from teeth with no previous endodontic treatment. All HIV-infected patients were undergoing HAART. The specimens were submitted to histopathologic and immunohistochemical analyses by using an optical microscope. Immunoexpression was graded into 2 levels, focal to weak and moderate to strong. The χ(2), Fisher exact, and Mann-Whitney tests were used to analyze all significant differences between groups.

RESULTS

Periapical cysts represented 70.6% and 52.9% of the lesions in the HIV-infected and non-HIV-infected groups, respectively; however, no statistically significant difference was observed (P = .481). There were no statistically significant differences between groups for the inflammatory cell profile and for any of the immunologic markers (P > .05).

CONCLUSIONS

There are no statistically significant differences of the cellular profile and expression of immunologic markers in chronic apical periodontitis between non-HIV-infected patients and HIV-infected patients undergoing HAART.