Evaluation of mast cells in periapical cysts, dentigerous cysts, and keratocystic odontogenic tumors

The Mystifying Role of Mast Cells in the Pathogenesis of Periapical Pathologies - a Systematic Review

INTRODUCTION

Oral periapical lesions present a significant global health burden, with their pathogenesis shrouded in complexity due to multifaceted mechanisms. Despite extensive research, the precise role of mast cells in their pathogenesis remains elusive. The present systematic review aimed to elucidate the mechanism of mast cells in the immunopathology of periapical lesions.

METHODS

An extensive literature search conducted across databases (MEDLINE via PubMed, Scopus, Cochrane Library, and EMBASE and gray literature) of original research articles that examined the role of mast cells in periapical lesions were investigated and selected for review. The risk of bias for each study was meticulously assessed using the QUADAS-2, and Review Manager 5.4 (RevMan v5.4, The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark) was utilized to generate the results.

RESULTS

A total of 41 published articles were included for data synthesis. The findings revealed significant variations in mast cell number within the fibrous capsule of periapical granuloma and periapical cyst, with notably elevated counts in the latter. Periapical granuloma manifested a predominance of granulated mast cells in the subepithelial region. In contrast, the periapical cyst exhibited a preponderance of degranulated mast cells in the deeper areas of the capsule.

CONCLUSIONS

The current evidence substantiates that mast cells play a crucial role in the pathogenesis, progression, fibrosis, and chronicity of periapical lesions.

Immunohistochemical Analysis of CD117 in the Mast Cells of Odontogenic Keratocysts

BACKGROUND

Odontogenic lesions contain mast cells (MCs), particularly those with a cystic appearance. Because of their high recurrence rates and aggressive clinical behaviour, odontogenic keratocysts (OKCs) require special treatment. A particular kind of protein called cluster of differentiation (CD) 117/ receptor tyrosine kinase (c-KIT) is present on the surface of many cells. Most hematopoietic cells lose their expression of KIT during the differentiation process, with the exception of MCs, which continue to express KIT throughout their lifetime.

AIM

Using the CD117 immunomarker, this immunohistochemical investigation sought to assess the presence and location of MCs in OKCs and examine the relationship between MC numbers in sporadic, syndromic, and recurrent OKCs.

METHODS

The study comprised 30 paraffin-embedded tissue specimens, and a histopathological diagnosis was made from hematoxylin and eosin-stained sections with a thickness of 4-5 µ. Out of 30 specimens, 21 were sporadic, six were recurrent OKCs, and three were syndrome-associated OKCs. CD-117/c-kit rabbit polyclonal primary antibody was used to stain the sections for observing MCs, which were then viewed under a light microscope with a digital camera and a desktop computer with MICAPS software for viewing images.

RESULT

To compare the number of MCs among OKCs, a one-way ANOVA test was used. Our study revealed that a statistically significant increase in MCs has been observed in the subepithelial and deep connective tissue of recurrent OKC (p < 0.05). However, a comparison of the mean MC value among three OKC subtypes did not reveal any statistically significant differences. An increased mast count was observed in the deep connective tissue layer of syndromic OKC under multiple comparisons.

CONCLUSION

Our study concluded that MCs were present in increased numbers both in the superficial and deep connective tissue of recurrent OKCs, indicative of their aggressive clinical behaviour. Increased mean MC counts observed in some of the sporadic cases may be an indicator of their chances of recurrence in the future.

Factors Influencing the Aggressive Behavior of Odontogenic Keratocyst: A Narrative Review

During odontogenesis, the dental lamina disintegrates, leaving behind the remnants. Odontogenic pathologies such as cysts and tumors can arise from these remnants. The odontogenic keratocyte (OKC) arises from dental lamina remnants. Among the cysts, the odontogenic keratocyst is the most controversial. There is convincing evidence that inflammation plays a significant role in the pathogenesis and expansion of OKCs. Several factors mediate the proliferative capacity of the epithelial lining. The presence of mast cells close to the epithelial lining, cystic pressure build-up by vascular endothelial growth factors (VEGFs), and other cytokines contribute to the cystic expansion. Fibroblast activation by inflammation in the connective tissue stroma and changes in the epithelial lining are responsible for the aggressive nature of OKC. The use of molecular methodologies gives more profound insights into the factors influencing the progression of the lesion and helps develop newer treatment modalities for OKC. This review describes the characteristics that determine the aggressive behavior of this unique cyst.

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.

Quantification and distribution of mast cells in oral periapical inflammatory lesions

Background:

Periapical granuloma and periapical cysts develop as a sequela of inflammation of dental pulp, usually a consequence of an infected root canal. Mast cells (MCs) have most frequently been implicated in the pathophysiology of periapical lesions such as periapical granulomas and cysts.

Aims:

The present study was undertaken to emphasize the presence and quantification of MCs in periapical lesions (granulomas and cysts) using toluidine blue stain, with an aim to elucidate their role in the pathogenesis of these lesions.

Materials and Methods:

The study comprised a total of 55 previously diagnosed cases (30 cases of radicular cyst and 25 cases of periapical granuloma) selected from the departmental archives. The MCs were quantified in all the sections in the three zones, namely the epithelial, subepithelial, and deeper connective tissue zones. The results were sent for statistical analysis.

Statistical Analysis:

Wilcoxon paired t-test and Mann–Whitney U test were applied for intra- and intergroup comparison MCs in different zones of periapical granulomas and radicular cyst, respectively.

Results:

A statistically significant difference was observed between the two lesions in all the three zones, i.e., epithelial, subepithelial, and in deeper connective tissue zone with P = 0.001.

Conclusion:

Although MCs were present in all the three zones of both periapical cysts and granuloma, they were predominantly observed in radicular cysts than in periapical granuloma. This suggests a significant role of MC in initiation, development, and progression of these periapical lesions.

Detection of mast cells in ameloblastomas and odontogenic keratocysts

Background

MCs (MCs) have been ascribed to mediating several diseases, including malignant neoplasms. These cells can play a role in angiogenesis, tissue remodeling and immune modulation and favor neoplasm progression. Despite the studies analyzing the contribution of MCs in odontogenic lesions, its biological behavior in ameloblastomas (AMBs) and odontogenic keratocysts (OKCs) remains unclear. This study aims to detect MCs in OKCs and AMBs and clarify the role of MCs in these lesions.

Material and Methods

A total of 40 odontogenic lesions were analyzed. This included 20 OKCs and 20 AMBs, 10 being the solid type and the other 10 being the unicystic type of AMB. All cases were histologically reviewed in hematoxylin-eosin. Clinical data, such as age, gender, location, size, radiographic presentation and, histologic patterns were collected from the clinical charts. The Mann–Whitney U test (MWU) was used verify the hypothesis, through inferential statistics. The level of significance used in the statistical test was 0.5%.

Results

MCs were observed in 60% of OKCs, and 35% of AMBs. The ratio of MCs observed in OKCs was 0.37, 0.48 in solid AMBs and 0.01 in unicystic AMBs. There was no significant difference between number of MCs in AMBs and OKCs, however, a significant difference was observed between solid and unicystic AMBs (p ≤ 0.01).

Conclusions

MCs may play an important role in the biological behavior of AMBs and OKCs. However, in this study it was not possible to confirm the contribution of MCs in the biological behavior of these lesions and more studies are needed to clarify this relation.

Key words:AMB, OKC, MCs, histochemistry, toluidine blue.

Relationship between mast cells and E-cadherin in odontogenic keratocysts and radicular cysts

OBJECTIVE

This study aimed to evaluate tryptase and E-cadherin protein expression in odontogenic keratocysts (OKCs) and radicular cysts (RCs) and their relationship with lesion size.

MATERIALS AND METHODS

Thirty OKC and 30 RC cases were analyzed by immunohistochemistry. Tryptase expression was quantitatively assessed using the quantification of mast cells, and expression of E-cadherin was semi-quantitatively analyzed estimating the proportion of positive cells: 1 = less than 25% of immunopositive cells; 2 = 26 to 50% of immunopositive cells; 3 = 51 to 75% of immunopositive cells; 4 = more than 75% of immunopositive cells. Data on cystic lesion sizes were obtained from patients' clinical files, based on previous radiographic exams, and the lesions were categorized into three groups: group 1 (< 2 to 2 cm); group 2 (> 2 to 4 cm), and group 3 (> 4 cm).

RESULTS

Higher mast cell means were found for RCs, with the predominance of degranulated mast cells in both OKCs and RCs (p = 0.082). Concerning the epithelial component, a higher concentration of degranulated mast cells was detected in RCs (p = 0.000). Regarding connective tissue, degranulated mast cells were more evident in OKCs (p = 0.762). A negative correlation was observed between E-cadherin expression and total number of mast cells (p = 0.011), degranulated mast cells (p = 0.040), and degranulated mast cells in both superficial (p = 0.035) and deep connective tissues (p = 0.009). Concerning lesion size, a negative correlation with total number of mast cells (p = 0.016) and number of degranulated mast cells (p = 0.049) was observed, both in the epithelial components. Herein, the larger the lesion size, the lower the number of degranulated mast cells in the epithelium (r = - 0.271; p = 0.49), suggesting that these cells play a role in the initial cystic expansion phase.

CONCLUSION

The higher expression of tryptase in degranulated mast cells was linked to a lower expression of E-cadherin, which may be related to a change in the epithelial permeability in these lesions, contributing to increased cystic content and lesion growth.

CLINICAL RELEVANCE

Evidence of the relationship between mast cells and E-cadherin in the growth of odontogenic cysts was studied.

Comparison of histochemical staining techniques for detecting mast cells in oral lesions

Mast cells are large cells with granular cytoplasm that participate in wound healing, angiogenesis and defense against pathogens. They also contribute to inflammation by initiating innate and acquired immunity. The granules of these cells exhibit characteristic staining properties. We investigated toluidine blue, astra blue, Alcian blue-pyronin Y and May-Grunwald Giemsa stains for mast cells in various oral lesions and assessed the efficacy of each for identifying mast cells. Sections were obtained from 10 each of diagnosed cases of inflammatory fibrous hyperplasia, periapical cyst, mild dysplasia, oral submucous fibrosis and oral squamous cell carcinoma and stained using the stains listed above. Mast cells were assessed for their presence, contrast of the mast cell in the connective tissue background and number. We found that May-Grunwald Giemsa stain was the best for identification of mast cells, although toluidine blue staining is less time-consuming. Overall we obtained better results using May-Grunwald Giemsa and toluidine blue for staining mast cells.

Evaluation of mast cell counts and microvessel density in reactive lesions of the oral cavity

Background. Reliable immunohistochemical assays to assess the definitive role of mast cells (MCs) and angiogenesis in the pathogenesis of oral reactive lesions are generally not available. The aim of the present study was to evaluate mast cell counts (MCC) and microvessel density (MVD) in oral reactive lesions and determine the correlation between MCC and MVD.

Methods. Seventy-five cases of reactive lesions of the oral cavity, including pyogenic granuloma, fibroma, peripheral giant cell granuloma, inflammatory fibrous hyperplasia, peripheral ossifying fibroma (15 for each category) were immunohisto-chemically stained with MC tryptase and CD31. Fifteen cases of normal gingival tissue were considered as the control group. The mean MCC and MVD in superficial and deep connective tissues were assessed and total MCC and MVD was computed for each lesion.

Results. Statistically significant differences were observed in MCC and MVD between the study groups (P < 0.001). MC tryptase and CD31 expression increased in the superficial connective tissue of each lesion in comparison to the deep con-nective tissue. A significant negative correlation was not found between MCC and MVD in oral reactive lesions (P < 0.001, r = -0.458).

Conclusion. Although MCs were present in the reactive lesions of the oral cavity, a direct correlation between MCC and MVD was not found in these lesions. Therefore, a significant interaction between MCs and endothelial cells and an active role for MCs in the growth of oral reactive lesions was not found in this study.

Analysis of the presence and location of mast cells in periapical cysts and periapical granulomas

ABSTRACT Objective: The aim of the present study was to locate mast cells in chronic periapical lesions (granulomas and cysts) by using histochemical techniques and toluidine blue staining. Methods: A quantitative, descriptive, cross-sectional and retrospective research was performed. The sample was obtained from histopathological reports in the archives of the laboratory of surgical pathology of the University of Pernambuco between November 2014 and May 2015. Results: Sixteen cases of granuloma and 21 cases of periapical cysts were selected. The stained slides were analyzed by two examiners at different times, in a double-blind study. Mast cells were found in 13 (61.9%) of the periapical cyst cases, located in the capsule of the lesion. In the periapical granuloma cases, mast cells were found in eight cases (50%), located in the granulation tissue. Conclusion: Mast cells were detected in both cysts and periapical granuloma, located in the capsule and granulation tissue, respectively. Mast cells were more prevalent in periapical cysts than in periapical granuloma.

Myofibroblasts and mast cells: influences on biological behavior of odontogenic lesions

Odontogenic lesions differ in their rate of recurrence and aggressiveness. This study aimed to evaluate the presence of myofibroblasts and mast cells in odontogenic lesions. Sample consisted of 20 cases each of dentigerous cysts, odontogenic keratocysts, and solid ameloblastomas. Histologic sections were submitted to immunohistochemistry using anti-α-smooth muscle actin and anti-tryptase antibodies. Myofibroblasts and mast cells were counted at ×400 magnification in 5 and 10 fields, respectively. Myofibroblasts were more frequent in ameloblastomas (24.41), followed by odontogenic keratocysts (16.21) and dentigerous cysts (11.85; P=.002). Granulated and degranulated mast cells were more frequent in dentigerous cysts (7.88 and 8.96, respectively), followed by odontogenic keratocysts (6.53 and 7.08) and ameloblastomas (5.21 and 1.88). The difference was only significant for degranulated mast cells (P<.05). Analysis of the correlation between myofibroblasts and mast cells (granulated and degranulated) revealed a moderate positive correlation only in ameloblastomas (R=0.621, P=.003). Probably, myofibroblasts are related to the biological behavior of the odontogenic lesions studied, particularly their aggressiveness. On the other hand, mast cells seem to be associated with inflammatory processes, which are more frequent in cystic lesions than in benign neoplasms. In addition, mast cells may induce the differentiation of fibroblasts into myofibroblasts, thus increasing the number of the latter.

The Possible Role of Mast Cells in the Odontogenic Cyst's Pathogenesis: A Comparative Study between Dentigerous Cyst and Keratocystic Odontogenic Tumor

Background. Recently, mast cells were recognized in the pathogenesis of more aggressive pathologic lesions. This study was aimed to evaluate and compare the density of mast cells in Dentigerous cyst (DC) and Keratocystic odontogenic tumor (KCOT) regarding their different clinical behavior. Method. This study was conducted on 23 and 26 cases of DC and KCOT, respectively. Four-micron sections were prepared for Toluidine blue staining and mast cell densities in two desired cysts were studied. Final data was analyzed via t-test and Mann-Whitney U test method regarding the significant level lower than 0.05. Results. Mast cell densities were significantly higher in KCOTs for deep and superficial layers and both layers (P < 0.05). The density of degranulated mast cells in the deeper layers and both layers was significantly higher in KCOTs (P < 0.05). However, the density of degranulated mast cells in the superficial layer had no significant difference (P > 0.05). Conclusion. It seems that mast cells may be involved in the pathogenesis of KCOT, but, regarding wide range of mast cell's biologic activities, further investigations are recommended to confirm the issue and prepare the details.

Interaction of stromal and microvascular components in keratocystic odontogenic tumors

OBJECTIVE

Little is known about the interaction of stromal components in odontogenic tumors. Thus, the aim of this study was to investigate mast cells (MCs), myofibroblasts, macrophages, and their possible association with angiogenesis and lymphangiogenesis in keratocystic odontogenic tumors (KCOTs).

MATERIAL AND METHODS

Thirty cases of KCOTs were included and analyzed by immunohistochemistry for mast cell tryptase, α-SMA, CD34, CD163, and D240. For comparative purpose, 15 radicular cysts (CRs) and 7 pericoronal follicles (PFs) were included.

RESULTS

There was an increase in MCs for RCs and this difference was significant when they were compared to KCOTS and PFs. A significant increase in the density of MFs was observed for KCOTs when compared to RCs and PFs (P = 0.00). No significant difference in CD163-positive macrophages (P = 0.084) and CD34-positive vessels (P = 0.244) densities was observed between KCOTs, RCs, and PFs, although KCOTs showed a higher density of all proteins. Significant difference in lymphatic vessel density was observed for KCOTs when compared to RCs and PFs (P = 0.00). Positive correlation was observed between mast cell tryptase and CD34 in KCOTs (P = 0.025).

CONCLUSIONS

A significant interaction between the MC population and CD34-positive vessels in KCOTs supported the hypothesis that MCs and blood vessels contribute to the stromal scaffold of KCOT.

Immunohistochemical Assessment of Mast Cells and Small Blood Vessels in Dentigerous Cyst, Odontogenic Keratocyst, and Periapical Cyst

PURPOSE

The aim of this study was to verify the density of mast cells (MCs) and microvessels in odontogenic cysts. Furthermore, the correlation between MCs and microvessels was evaluated to assess the contribution of MCs to angiogenesis and growth of odontogenic cysts. This approach may be a basis for the development of future pharmaceuticals addressed to MCs performance to manage odontogenic cysts. To our knowledge, no study investigating the correlation between MCs and microvessels has been performed to date.

METHODS

60 cases of odontogenic cysts consisting of 20 radicular cysts (RCs), 20 odontogenic keratocysts (OKCs) and 20 dentigerous cysts (DCs) were included in this study. Five high power fields in superficial connective tissue and five high power fields in deep connective tissue were counted for each sample. Moreover, a total mean of ten fields was calculated.

RESULTS

RC showed the highest mean numbers of MCs and microvessels (p<0.05). The subepithelial zones of all cysts contained more MCs and microvessels compared to the deeper zones. A statistically significant correlation between the numbers of MCs and microvessels was not observed (r=0.00, p=0.49).

CONCLUSION

Although the number of MCs was not significantly associated with microvessels, these cells may be related to the growth of odontogenic lesions, particularly RCs. Further studies on the in vivo functions of MCs will make the concept more clear.

Effect of laser therapy on the inflammatory response induced by endodontic medications implanted into the subcutaneous tissue of rats

INTRODUCTION: Endodontic medications contain toxic components that cause varying degrees of inflammation.OBJECTIVE: This study evaluated the effect of laser therapy on the inflammatory response induced by intracanal medications implanted into the subcutaneous tissue of rats using a quantitative analysis of mast cells.MATERIAL AND METHOD: Polyethylene tubes containing the medications were implanted in the dorsum of 60 rats divided into six groups, including HS (P.A. calcium hydroxide paste), HL (P.A. calcium hydroxide paste and laser therapy), HPS (P.A. calcium hydroxide paste with camphorated paramonochlorophenol), HPL (P.A. calcium hydroxide paste with camphorated paramonochlorophenol and laser therapy), IS (iodoform with saline) and IL (iodoform with saline and laser therapy). The animals were euthanized eight or fifteen days after surgery, and samples were removed and embedded in paraffin. Histological sections were stained with 0.2% toluidine blue for the quantification of mast cells. Analysis of variance (ANOVA) and Tukey's post-hoc test were applied to determine significant differences in the number of mast cells between groups (p<0.05).RESULT: There was a decrease in mast cells for the HL, HPL and IL groups when compared with the HS, HPS and IS groups at both time points. There was no statistically significant difference between the HPS and HPL groups at the eight-day time point.CONCLUSION: Laser therapy was effective at modulating the inflammatory response induced by endodontic medications by significantly reducing the number of mast cells.

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

INTRODUCTION

Mast cells and macrophages are important components of the inflammatory infiltrate found in inflammatory periapical diseases. Several cytokines participate in the mechanisms of inflammation, tissue repair, and bone resorption associated with periapical cysts. The aim of the present study was to evaluate the distribution of mast cells and macrophages and the expression of interleukin-6 (IL-6) in periapical cysts.

METHODS

Thirty periapical cysts were selected for the study, and clinical, demographic, and gross information from the cases was obtained from the laboratory records. Five-micrometer sections stained with hematoxylin-eosin were reviewed for analysis of the microscopic features of the cysts, and 3-μm sections on silanized slides were used for immunohistochemical reactions with anti-tryptase, anti-CD68, and anti-IL-6.

RESULTS

There was no statistically significant difference in the mean number of mast cells and macrophages when comparing superficial and deep regions of the fibrous capsule of the cysts. Mean number of mast cells on the superficial region of the fibrous capsule was higher in cysts showing intense superficial inflammation and exocytosis. Macrophages were more commonly found in areas showing IL-6 expression, and IL-6 was less expressed in deep regions of the fibrous capsule in cysts showing greater gross volume.

CONCLUSIONS

The results reinforced the participation of mast cells and macrophages in the pathogenesis of periapical cysts and suggested that IL-6 is not the major bone resorption mediator in larger periapical cysts.

Immunophenotypic characterization and distribution of dendritic cells in odontogenic cystic lesions

OBJECTIVE

To analyze the expression and distribution patterns of mature dendritic cells (mDCs) and immature DCs (imDCs) in radicular cysts (RCs), dentigerous cysts (DtCs), and keratocystic odontogenic tumors (KCOTs).

MATERIALS AND METHODS

Forty-nine odontogenic cystic lesions (OCLs) (RCs, n = 20; DtCs, n = 15; KCOTs, n = 14) were assessed using the following markers: S100, CD1a and CD207 for imDCs; and CD83 for mDCs.

RESULTS

Almost all cases were S100, CD1a, and CD207 positive, whereas 63% were CD83 positive. RCs presented greater number of immunostained cells, followed by DtCs, and KCOTs. The number of S100+ cells was greater than both CD1a+ and CD207+ cells (P < 0.001), which showed approximately similar amounts, followed by lower number of CD83+ cells (P < 0.001) in each OCL type. Different from S100+ cells, both CD1a+ and CD207+ cells on the epithelium (P < 0.05) and CD83+ cells on the capsule (P < 0.05) were preferentially observed. In RCs, significant correlation was found between the thickness epithelium with S100+ and CD1a+ cells, and between the degree of inflammation with CD83+ cells.

CONCLUSIONS

Dendritic cell populations in OCLs can be phenotypically heterogeneous, and it could represent distinct lineages and/or functional stages. It is suggested that besides DC-mediated immune cell interactions, DC-mediated tissue differentiation and maintenance in OCLs should also be considered.