Immunohistochemical study of apical periodontal cysts

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.

Immunohistochemical Analysis of Galectins-1, -3, and -7 in Periapical Granulomas, Radicular Cysts, and Residual Radicular Cysts

INTRODUCTION

Galectins play important roles in immunoinflammatory responses, but their participation in the development of periapical lesions remains unclear. This study aimed to evaluate the expressions of galectins-1, -3, and -7 in periapical lesions, correlating them with the intensity of the inflammatory infiltrate and the pattern of the cystic epithelium.

METHODS

Twenty periapical granulomas (PGs), 20 radicular cysts (RCs), and 20 residual radicular cysts (RRCs) were submitted to immunohistochemistry using anti-galectin-1, -3, and -7 antibodies. The percentage of immunopositive cells in epithelial and connective tissues was determined.

RESULTS

In connective tissue, PGs exhibited higher cytoplasmic/membrane expression of galectins-1 and -7 than RCs and RRCs (P < .05). There was higher nuclear expression of galectin-1 in PGs compared with RCs and RRCs (P < .05). The expression of galectins-1 and -7 in connective tissue was higher in lesions with grade III inflammation (P < .05). No significant differences in galectin-3 immunoexpression were observed for any of the parameters evaluated (P > .05). In the epithelial component, a higher nuclear expression of galectin-7 was detected in RRCs (P < .05), and a higher cytoplasmic/membrane expression of this protein was found in cysts with hyperplastic epithelium (P < .05). Positive correlations were observed between the nuclear and cytoplasmic/membrane expression of galectin-1 in connective tissue (P < .05) as well as between the nuclear and cytoplasmic/membrane expression of galectin-7 in epithelial tissue of cysts (P < .05).

CONCLUSIONS

Galectins-1 and -7 may play important roles in the pathogenesis of PGs, RCs, and RRCs. On the other hand, the present results suggest only a minor involvement of galectin-3 in the development of these lesions.

Stem Cell Marker Expression in Persistent Apical Periodontitis

INTRODUCTION

This study evaluated the expression of CD90 (mesenchymal stem cell) and Sox2 (progenitor stem cell) markers in persistent apical periodontitis (PAP) (n = 16) and primary periapical lesions (PPLs) (n = 10).

METHODS

All samples were classified histologically according to the intensity of inflammatory cell infiltrate in the periapical lesion. Immunohistochemistry was used to detect CD90 and Sox2 in PAP and PPLs. The Spearman correlation coefficient and the Mann-Whitney U test were used to analyze data at the 5% significance level.

RESULTS

CD90 expression was found in mesenchymal cells and vascular endothelial cells of 68.5% of all cases of PAP. There was no correlation between CD90 expression and histopathological diagnosis (P = .053) or inflammatory cell infiltrate intensity (P = .112). CD90 staining was predominantly found in the vascular endothelial cells of 30% (n = 3) of PPLs. CD90 expression was significantly higher in PAP than in PPLs (Mann-Whitney U test, P < .05). Sox2 expression was found in all cases of PAP. Eventually, all mesenchymal and chronic inflammatory cells exhibited Sox2 expression. There was no correlation between Sox2 expression and histopathological diagnoses (P = .749), inflammatory cell infiltrate intensity (P = .510), or acute or chronic inflammatory cell infiltrate (P = .256). Sox2 expression was found in 100% of PPLs. There was no difference in Sox2 expression between PAP and PPLs (P = .477).

CONCLUSIONS

Mesenchymal stem cells may contribute to the immunosuppressive environment in PAP. Additionally, distinct stem cell sources may be associated with the chronic nature of PAP as well as with the development of PPLs.

Study of the relationship between mononuclear inflammatory infiltrate and Ki-67 and basement membrane and extracellular matrix protein expression in radicular cysts

AIM

To evaluate the relationship between mononuclear inflammatory infiltrate and the expression of a proliferative immunomarker (Ki-67) as well as to evaluate basement membrane and extracellular matrix proteins (laminin and collagen type IV) in radicular cysts and dentigerous cysts (DC).

METHODOLOGY

Immunohistochemical analyses were performed in heavily inflamed radicular cysts (HIRC), slightly inflamed radicular cysts (SIRC) and DC (n = 20) using Ki-67 (Dako(®) , 1 : 50), anticollagen type IV (DBS(®) , 1 : 40) and antilaminin (DBS(®) , 1 : 20). The data were analysed using anova/Tukey's test (Ki-67) and Kruskal-Wallis/Dunn's test (collagen type IV and laminin) (P < 0.05).

RESULTS

The immunoexpression of Ki-67 was significantly greater in the SIRC group compared with the HIRC and DC (P = 0.0040). Likewise, the immunoexpression of collagen type IV in the basement membrane of the SIRC group was significantly more continuous (P = 0.0475) than in the HIRC group. DC had significantly less collagen type IV in extracellular matrix immunoexpression than HIRC and SIRC (P = 0.0246). Laminin was absent in the basement membrane in the SIRC and DC groups, and the extracellular matrix of the HIRC was weak and punctate.

CONCLUSION

The presence of inflammatory factors in the radicular cyst wall modified the expression of proliferation factors in the epithelial lining and the expression of collagen type IV and laminin in the basement membrane, but did not modify extracellular matrix behaviour in radicular cysts.

Correlation between inflammatory infiltrate and epithelial lining in 214 cases of periapical cysts

The aim of this study was to evaluate the prevalence of periapical cysts, identify their clinical and microscopic features and correlate their microscopic features with the inflammatory infiltrate present in the lesion site. A total of 214 cases were collected over a 10-year period. Clinical data, including gender, age, race, symptoms and location of the lesion, were recorded. Two independent examiners with no prior knowledge of the patients' clinical data conducted the microscopic evaluations. Statistical analyses were performed using Fisher's or chi-square tests at a 5% level of significance. The results showed that periapical cysts were more prevalent in white women, with a mean age of 35 years, and in the anterosuperior region. The majority of the lesions were lined by atrophic cystic epithelium, which was associated with moderate inflammatory infiltrate in the cystic capsule (p < 0.01), with a diffuse localization pattern (p = 0.03) and absence of neutrophils (p = 0.01). Our findings suggest that periapical cysts lined by atrophic epithelium are related to the presence of moderate mononuclear inflammatory infiltrate.

Syndecan-1 (CD138) and Ki-67 expression in odontogenic cystic lesions

The aim of this study was to assess the immunohistochemical expression of syndecan-1 (CD138) and Ki-67 in radicular cysts (RC), dentigerous cysts (DC) and keratocystic odontogenic tumors (KOT). Thirty-five RC, 22 DC and 17 KOT were used in the study and immunohistochemical reactions using anti-syndecan-1 and anti-Ki-67 antibodies were performed by the streptavidin-biotin-peroxidase method. Fisher's exact test and Spearman's correlation coefficient were used for statistical analysis of data. Among the studied lesions, no differences in the syndecan-1 expression were observed, but the suprabasal expression of Ki-67 was significantly higher in KOT (p<0.0001), when compared with RC and DC. In RC, there was positive correlation between the expression (p=0.02) and intensity (p=0.0001) of syndecan-1 and between the intensity of syndecan-1 and Ki-67 expression (p=0.01). In the KOT, Ki-67 expression in the suprabasal layer correlated positively with the expression (p=0.01) and intensity (p=0.01) of syndecan-1. The expression of syndecan-1 does not seem to be a determinant factor of the distinct histopathological features and biological behavior of the studied lesions. Nevertheless, positive correlation between syndecan-1 and a cell proliferation marker was observed in RC and KOT.

T lymphocyte activation and cytokine expression in periapical granulomas and radicular cysts

INTRODUCTION

Radicular cysts (RCs) are periapical lesions resulting in jaw bone destruction. The inflammatory dental periapical granuloma (PG) is considered to be the origin of RC formation; however the mechanism of RC development remains unclear.

METHODS

Cell suspension from the surgically extirpated tissue of 27 RCs and 25 PGs was obtained. Bacteriological analysis of the PG tissue samples was performed in order to define two major groups of PG according to the prevailing causative bacterial infection: the streptococcal PG (PG-S, n=10) and the anaerobe PG (PG-A, n=9) group. The inflammatory response of tissue infiltrating lymphocytes was assessed by following T lymphocyte activation (HLA-DR expression) as well as interferon gamma (IFN-gamma) and interleukin 4 (IL-4) production which were evaluated by the flow cytometry.

RESULTS

In comparison to RC both types of PG contained a higher proportion of activated T cells (HLA-DR) and lower proportion of IL-4 producing cells. PG-A tissue contained increased percentage of CD3 cells and increased percentage of T helper 1 (Th1) cells in comparison with PG-S. In RC the IFN-gamma production is higher than in streptococcal PG-S but similar as in PG-A.

DISCUSSION

Tissue infiltration by Th2 cells and IL-4 production is likely to play an etiopathogenic role in RC formation.

Immunoexpression of vascular endothelial growth factor in periapical granulomas, radicular cysts, and residual radicular cysts

OBJECTIVE

Our aim was to assess and compare the immunoexpression of vascular endothelial growth factor (VEGF) in periapical granulomas (PGs), radicular cysts (RCs), and residual radicular cysts (RRCs), relating it to the angiogenic index and the intensity of the inflammatory infiltrate.

STUDY DESIGN

Twenty PGs, 20 RCs, and 10 RRCs were evaluated by immunohistochemistry using anti-VEGF antibody. Angiogenic index was determined by microvessel count (MVC) using anti-von Willebrand factor antibody.

RESULTS

The PGs and RCs showed higher expression of VEGF than the RRCs. Lesions presenting few inflammatory infiltrate revealed the lowest immunoexpression of VEGF (P < .05). Irrespective of the intensity of the inflammatory infiltrate, most of the RCs and RRCs showed moderate to strong epithelial expression of VEGF. Lesions showing dense inflammatory infiltrate presented higher MVC indices (P < .05). VEGF expression and MVC did not reveal a significant correlation (P > .05).

CONCLUSIONS

VEGF is present in periapical inflammatory lesions but at a lower level in RRCs. The expression of this proangiogenic factor is closely related to the intensity of the inflammatory infiltrate in these lesions.

Comparative immunohistochemical and quantitative analysis of inflammatory cells in symptomatic and asymptomatic chronic periapical lesions

Background/Aim. It has been demonstrated that lymphocytes, plasma cells, macrophages and neutrophil granulocytes represent the predominant cells of the inflammatory lesion of the dental granulomas. Other cells, such as mast cells, eosinophils, dendritic cells comprise minor, but functionally important cell populations. Most of the data considering cells that take part in these processes have been derived from immunohistological studies. This study was undertaken with the aim to determine the phenotype profile of inflammatory cells of dental granulomas using immunohistochemical method in order to study the differences of their quantitative properties and distribution between symptomatic and asymptomatic lesions. Methods. The material for the analysis originated from 42 individuals with clinic and radiographic diagnosis of chronic periapical lesions. The tissue was take either during the periradicular surgery, or tooth extraction. Cryostat tissue sections were stained using the alkaline phosphatase-antialkaline phosphatase assay (APAAP). This method is highly valid and sensitive using a panel of specific monoclonal antibodies: CD3, CD4, CD8, CD19, CD38, CD14, CD1a, CD83, CD80, CD86, CD45 and CD123. Results. The composition of the cell population revealed that there was no homogenous and site-specific pattern of the distribution of inflammatory cells. The results of our investigation revealed that the majority of inflammatory cells comprised lymphocytes and plasma cells, followed by subpopulations CD4+, CD8+ and CD14+ cells. Much lower in number were CD80+, CD86+ and CD83+ and CD1a+ cells. There were no statistically significant differences in mean values of inflammatory cells number between symptomatic and asymptomatic lesions, with the exception of CD86+ cells, the number of which was statistically higher in symptomatic lesions. Conclusion. Inflammatory infiltrate cells in dental granulomas are dominated by T- and Blymphocytes. It points out the complexity of immunopathogenic events in imitiating and progressing of dental granulomas that involve mechanisms of both cellular and humoral immunity. Regarding the quantitative presence of immunocompetent cells in symptomatic and asymptomatic lesions no statistically significant difference was determined unless in mature dendritic cells present in symptomatic lesions.

Apoptosis in epithelial cells of apical radicular cysts

AIM

To investigate the occurrence of apoptotic cell death in the epithelium of radicular cysts and to compare its frequency in lesions presenting a distinct functional state.

METHODOLOGY

Twenty radicular cysts were selected and arranged into two groups with 10 lesions in each group: atrophic (quiescent) and hyperplastic (active) epithelium. Morphologic investigations of apoptosis were conducted by means of optic microscopy in haematoxylin and eosin slides. Immunohistochemical techniques to detect the bcl-2 protein were carried out by streptavidin-biotin-peroxidase assay. In both instances, 30 sequential high-power microscopic fields were observed to determine apoptotic (AI) and bcl-2 immunostaining (bcl-2I) indexes. The presence of AI and bcl-2I within the two groups was compared using the t-test. Correlation between the AI and the bcl-2I was investigated using the Spearman test.

RESULTS

Apoptosis was detected in the epithelium of all cysts. Higher AI levels were found in lesions with an atrophic (0.17 +/- 0.19) rather than a hyperplastic (0.10 +/- 0.10) epithelium. The same was found for the bcl-2I levels (0.06 +/- 0.03 vs. 0.04 +/- 0.01, respectively). However, these differences were not statistically significant. A positive and significant correlation was found between AI and bcl-2I.

CONCLUSIONS

Apoptosis was always present in the epithelium of the lesions and was more frequent in lesions with atrophic (quiescent) epithelium.

Inflammatory infiltrate of chronic periradicular lesions: an immunohistochemical study

AIM

To determine the cellular profile of human chronic periradicular lesions using immunohistochemical methods in order to study the differences in the cell infiltrate of periradicular granulomas and cysts.

METHODOLOGY

The study population consisted of 45 individuals without any systemic disease. Biopsies were obtained during periradicular surgery. Paraffin-embedded sections were stained by the avidin-biotin complex method (ABC), whilst cryostat tissue sections were stained using the alkaline phosphatase antialkaline phosphatase assay (APAAP). These methods are highly valid and sensitive using a panel of specific monoclonal antibodies: CD4, CD8, CD3, CD10, HLADR, CD20, CD45RO, CD68 and CD57. The 45 specimens were characterized by the use of both techniques.

RESULTS

The 45 specimens were histologically diagnosed as: 25 periradicular granulomas, 17 periradicular cysts and 3 scar tissues. No statistically significant differences were detected in the inflammatory infiltrate between periradicular granulomas and cysts. Observation of the sections showed that the majority of inflammatory cells consisted of T and B lymphocytes and macrophages. T and B lymphocytes were equally distributed in 60% of the cases. The T4/T8 ratio ranged approximately from 1 to 3 and greater, being consistent with inflammation of periradicular tissues. The final differentiation of B lymphocytes to plasma cells was also detected, whilst natural killer (NK) cells were found in only 10 cases (22%). Moreover, antigen presenting cells and T suppressor/cytotoxic cells were found to be associated with both pre-existing and newly formed epithelium.

CONCLUSIONS

Periradicular granulomas and cysts represent two different stages in the development of chronic periradicular pathosis as a normal result of the process of immune reactions that cannot be inhibited.

Study of the expression of CD68+ macrophages and CD8+ T cells in human granulomas and periapical cysts

In the periapex, the interaction among inflammatory cells and microorganisms and their products results both in specific and nonspecific immune responses. Many studies have reported quantitative analysis of the immunocompetent cells in periapical lesions, but the exact ratio of these cells in cysts and granulomas remains unknown. In the present study, we undertook a quantitative analysis of CD68+ cells and CD8+ T cells in human periapical granulomas and cysts. Immunoperoxidase staining revealed that CD68+ cells were present in both lesions, with no statistically significant difference, mainly distributed in the inner portion of the lesion, where the inflammation site is more active. On the other hand, CD8+ lymphocytes were more numerous in cysts. Thus, it appears that CD8+ T cells may play a more important role in a later phase of periapical lesion progression, probably exerting regulatory or cytotoxic functions in cellular immune response, which may lead to the stabilization of these lesions.

CD57+ cells in radicular cyst

AIM

As CD57 antigen is an important modulator of the immune system, the purpose of the present study was to compare the expression of this antigen on radicular cysts (RC) with hyperplastic or atrophic epithelium.

METHODOLOGY

Twenty cases of RC were retrieved and classified as atrophic or hyperplastic. A biotin-streptavidin amplified system was used for identification of the CD57 receptor.

RESULTS

The results demonstrated a greater percentage of CD57+ cells in RC with atrophic epithelium compared to hyperplastic epithelium.

CONCLUSION

As the expression of CD57 is indicative of immunosuppression, it may constitute a negative immunomodulator of RC's epithelium growth. Further studies are necessary to understand the importance of this cell to the biological activity or inactivity of RC's epithelium development.