The IL-1ß-p65 axis stimulates quiescent odontogenic epithelial cell rests via TGF-ß signalling to promote cell proliferation of the lining epithelia in radicular cysts: A laboratory investigation.

AIM: Cyst formation of the jaws is frequently accompanied by the proliferation of odontogenic epithelial cells located in the periodontal ligament (PDL), which consists of heterozygous cells and includes the most fibroblasts. The lining epithelium of radicular cyst, an odontogenic cyst of inflammatory origin, is derived from the proliferation of the remnants of the Hertwig epithelial root sheath (odontogenic epithelial cell rests of Malassez; ERMs) in the PDL. ERMs are maintained at a lower proliferative state under physiological conditions, but the regulatory mechanisms underlying the inflammation-dependent enhanced-proliferative capabilities of ERMs are not fully understood. The aim of this study was to evaluate the effects of cytokine pathway association between TGF-ß signalling and IL-1ß signalling on the regulation of odontogenic epithelial cell proliferation using radicular cyst pathological specimens and odontogenic epithelial cell lines. METHODOLOGY: Immunofluorescence analyses were performed to clarify the expression levels of Smad2/3 and Ki-67 in ERMs of 8-week-old mouse molar specimens. In radicular cyst (n = 52) and dentigerous cysts (n = 6) specimens from human patients, the expression of p65 (a main subunit of NF-κB), Smad2/3 and Ki-67 were investigated using immunohistochemical analyses. Odontogenic epithelial cells and PDL fibroblastic cells were co-cultured with or without an inhibitor or siRNAs. Odontogenic epithelial cells were cultured with or without TGF-ß1 and IL-1ß. The proliferative capabilities and Smad2 phosphorylation levels of odontogenic epithelial cells were examined. RESULTS: Immunohistochemically, Smad2/3-positivity was increased, and p65-positivity and Ki-67-positivity were decreased both in ERMs and in the epithelial cells in dentigerous cysts, a non-inflammatory developmental cyst. In contrast, p65-positive cells, along with the expression of Ki-67, were increased and Smad2/3-positive cells were decreased in the lining epithelia of radicular cysts. Co-culture experiments with odontogenic epithelial cells and PDL fibroblastic cells revealed that PDL cells-derived TGF-ß1/2 and their downstream signalling suppressed odontogenic epithelial cell proliferation. Moreover, TGF-ß1 stimulation induced Smad2 phosphorylation and suppressed odontogenic epithelial cell proliferation, while IL-1ß stimulation reversed these phenotypes through p65 transactivation. CONCLUSIONS: These results suggest that IL-1ß-p65 signalling promotes odontogenic epithelial cell proliferation through suppressing TGF-ß-Smad2 signalling, which would be involved in the pathogenesis of radicular cysts.

Differentiation of radicular cysts and radicular granulomas via texture analysis of multi-slice computed tomography images.

OBJECTIVES: This study aimed to establish a method for differentiating radicular cysts from granulomas via texture analysis (TA) of multi-slice computed tomography (CT) images. METHODS: A total of 222 lesions with multi-slice computed tomography images acquired at our hospital between 2013 and 2022 that were pathologically diagnosed were included in this study. Cases of contrast-enhanced images, severe metallic artefacts, and lesions that were not sufficiently large to be analysed were excluded. The images were chronologically divided into a training group and a validation group. The radiological characteristics were determined. Subsequently, a TA was performed. Pyradiomics software was used for the TA of three-dimensionally segmented volumes extracted from 2 mm slice thickness images with a soft-tissue algorithm. Features that differed significantly between the two lesions in the training group were extracted and used to create machine-learning models. The discriminative ability of these models was evaluated in the validation group using receiver operating characteristic curve analysis. RESULTS: A total of 131 lesions, comprising 28 radicular cysts and 103 granulomas, were analysed. Forty-three texture features that exhibited significant variations were extracted. A support vector machine and decision tree model, with areas under the curves of 0.829 and 0.803, respectively, were created. These models showed high discriminative abilities, even for the validation group, with areas under the curve of 0.727 and 0.701, respectively. Both models showed superior performance compared with that of the models based on radiographic findings. CONCLUSION: Discriminatory models were established for the TA of radicular cysts and granulomas using CT images.

CITED1 expression in odontogenic cysts.

BACKGROUND: Originating from odontogenic tissue, Odontogenic cysts are pathological cavities lined with epithelial cells and surrounded by fibrous connective tissue. This study investigated expression of CITED1 protein in different types of odontogenic cysts. MATERIAL AND METHOD: 40 keratocysts, 40 radicular cysts, and 40 dentigerous cysts were excised and processed for routine paraffin wax embedding protocol. Macroscopic and panoramic radiographies images were used for diagnosis. Demographical properties and dental parameters were recorded. Cystic tissues were stained with hematoxylin-eosin dye and CITED1 antibody. Semi-quantitative analysis was performed for immune staining. The protein-protein interaction network, hub gene detection and KEGG analysis were conducted using Cytoscape software. RESULT: Odontogenic keratocysts was imaged with 6-8 layered epithelial cells and fibrous cyst walls with inflammatory cells. Radicular cysts had stratified squamous epithelium with varying thickness, ciliated cells, and Rushton hyaline bodies. Dentigerous cysts presented hyperplastic non-keratinized epithelium, fibrous tissue, rete ridges, and inflammatory cells. CITED1 immunoexpression was highest in odontogenic keratocysts, followed by radicular cysts, and lowest in dentigerous cysts. Nuclear and cytoplasmic CITED1 expression was significantly elevated in odontogenic keratocysts compared to radicular and dentigerous cysts. The top five targets of CITED1 were identified, primarily showing enrichment in hormone and cancer related pathways. CONCLUSIONS: Positive CITED1 expression in all three types of odontogenic cysts suggest a potential role for CITED1 in the pathogenesis of odontogenic cysts, particularly in keratocysts. Further investigations are needed to elucidate the exact mechanisms underlying the differential expression of CITED1 and its implications for the development and progression of odontogenic cysts.

Pediatric Oral Pathology: Odontogenic Cysts.

Cysts encountered in the head and neck typically arise from epithelium that would normally be programmed to form teeth or tooth-supporting structures (odontogenic epithelium). These cysts come with a confusing array of similar-sounding names and histopathologic features that are sometimes shared between conditions. Here we describe and contrast the relatively-common lesions: hyperplastic dental follicle, dentigerous cyst, radicular cyst, buccal bifurcation cyst, odontogenic keratocyst, glandular odontogenic cyst, and the less-common gingival cyst of the new-born and thyroglossal duct cyst. The goal of this review is to help clarify and simplify these lesions for the general pathologist, pediatric pathologist, and surgeon.

The expression of cyclic GMP-AMP synthase in human apical periodontitis: A laboratory investigation.

AIM: As a key DNA sensor, cyclic GMP-AMP synthase (cGAS) has emerged as a major mediator of innate immunity and inflammation. Human apical periodontitis has yet to be studied for the presence of cGAS. This investigation was conducted to determine if cGAS is involved in the pathological process of human apical periodontitis. METHODOLOGY: Sixty four human periapical lesions, comprising 20 periapical granulomas and 44 radicular cysts, were employed in this investigation. Healthy gingiva (n = 6), dental pulp (n = 3), and apical papilla (n = 3) were used as control samples. The expression of cGAS in the periapical tissues was discovered using immunohistochemical staining. mRNA-Sequencing and qRT-PCR were utilized to determine the differentially expressed genes (DEGs) associated with DNA-sensing signalling in periapical lesions compared to the healthy control. Immunofluorescence labelling was used to identify the co-expression of cGAS, interleukin-1ß, and interleukin-18. RESULTS: A significantly greater expression level of cGAS was discovered in the periapical lesions, with no significant difference between radicular cysts and periapical granulomas. mRNA-Sequencing analysis and qRT-PCR identified differentially expressed mRNA, such as cGAS and its downstream DEGs, between periapical lesions and healthy control tissues. Immunofluorescence labelling further revealed that cGAS, interleukin-1, and interleukin-18 were co-localized. CONCLUSIONS: These observations imply that along with the synthesis of interleukin-1 and interleukin-18, cGAS may be involved in the aetiology of apical periodontitis.

Immunohistochemical evaluation of cyclooxygenase-2 and mast cell density in periapical lesions.

AIM: Periapical granuloma (PG) and cyst (PC) are formed as a protective response consequent to pulpal infection leaching through the apical foramen and lateral canals. Various inflammatory mediators like mast cells and cyclooxygenase (COX)-2 are involved in this intricate process. This pilot study aimed to evaluate and compare the immunoexpression of tryptase and COX-2 in periapical granuloma and periapical cyst, and also correlate them with intensity of inflammatory infiltrate and thickness of cystic epithelial lining. METHODOLOGY: An observational and cross-sectional study was conducted on paraffin-embedded tissue sections of 50 PGs and 50 PCs submitted for morphological and immunohistochemical analysis using anti-tryptase and anti-COX-2 antibodies. The mean number of mast cells (total, granulated and degranulated), mean COX-2 expression and inflammatory score was calculated. The data obtained were analysed using Mann Whitney U, Student's T, Chi-square and Spearman correlation test (p < .05). RESULTS: The inflammatory score, total mast cells and COX-2 expression were similar in PGs and PCs (p = .352, .339 and .352) however, the degranulated mast cells were highly significant in PC while granulated mast cells were highly significant in PG respectively (p < .001 in both). Although a non-significant correlation existed between COX-2 and total mast cells in both groups but, total mast cells were significantly correlated with epithelial thickness in PC (p = .029). CONCLUSIONS: Mast cells and cyclooxygenase-2 proved to be independent inflammatory markers in periapical lesions. Further studies should be planned on mast cell and COX-2 inhibitors as treatment modalities of periapical lesions.

The Dilemma Of Management Of Cystic Lesions; An Uncertain Way Forward: A Case Report.

Periapical diseases ranges from mild granulomatous lesions to large cystic ones, with the treatments corresponding to their respective pre-operative diagnoses. However, the determination of cause of periapical radiolucency is impossible on pre-operative clinical and radiographic examinations. We present a case highlighting the difficulties encountered in treating a periapical cyst using the current evidence in literature. It demonstrates the uncertainty involved in treating such lesions, owing to the impossible nature of determining the histopathological nature of the cyst, i.e., being either true cysts or pocket cysts. This case includes orthograde re-treatment; decompression of the cystic lesion, followed by peri-apical surgery of two teeth over a course of three years; and the uncertain outcomes encountered after each phase of the treatment.

Surgical and prosthodontics management of a perforating giant radicular cyst in anterior maxilla: A case report.

Radicular cyst is the most common type of odontogenic cyst associated with the apex of non-vital teeth. The lining of the radicular cyst usually arises from the epithelial rests of Malassez. These cyst usually persists even after the elimination of microbial load from the root canals. Surgical removal is deemed necessary for the management. For larger lesions extending to the facial or palatal cortical plates, additional regenerative procedures such as bone grafting along with collagen membrane are warranted. This case report describes the surgical and prosthetic management of a giant radicular cyst that was perforating the cortical plates in the anterior maxilla.

Bevacizumab or fibronectin gene editing inhibits the osteoclastogenic effects of fibroblasts derived from human radicular cysts.

Fibronectin (FN) is a main component of extracellular matrix (ECM) in most adult tissues. Under pathological conditions, particularly inflammation, wound healing and tumors, an alternatively spliced exon extra domain A (EDA) is included in the FN protein (EDA+FN), which facilitates cellular proliferation, motility, and aggressiveness in different lesions. In this study we investigated the effects of EDA+FN on bone destruction in human radicular cysts and explored the possibility of editing FN gene or blocking the related paracrine signaling pathway to inhibit the osteoclastogenesis. The specimens of radicular cysts were obtained from 20 patients. We showed that the vessel density was positively associated with both the lesion size (R = 0.49, P = 0.001) and EDA+FN staining (R = 0.26, P = 0.022) in the specimens. We isolated fibroblasts from surgical specimens, and used the CRISPR/Cas system to knockout the EDA exon, or used IST-9 antibody and bevacizumab to block EDA+FN and VEGF, respectively. Compared to control fibroblasts, the fibroblasts from radicular cysts exhibited significantly more Trap+MNCs, the relative expression level of VEGF was positively associated with both the ratio of EDA+FN/total FN (R = 0.271, P = 0.019) and with the number of Trap+MNCs (R = 0.331, P = 0.008). The knockout of the EDA exon significantly decreased VEGF expression in the fibroblasts derived from radicular cysts, leading to significantly decreased osteoclastogenesis; similar results were observed using bevacizumab to block VEGF, but block of EDA+FN with IST-9 antibody had no effect. Furthermore, the inhibitory effects of gene editing on Trap+MNC development were restored by exogenous VEGF. These results suggest that EDA+FN facilitates osteoclastogenesis in the fibrous capsule of radicular cysts, through a mechanism mediated by VEGF via an autocrine effect on the fibroblasts. Bevacizumab inhibits osteoclastogenesis in radicular cysts as effectively as the exclusion of the EDA exon by gene editing.

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 ß, TNF-α and IL-6 cytokines. METHODOLOGY: Twenty-four cases of periapical cysts were selected. Immuno-expressions of IL-1 ß, 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-1ß, 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.

Differential diagnosis between a granuloma and radicular cyst: effectiveness of magnetic resonance imaging.

AIM: To investigate the diagnostic reliability and accuracy of magnetic resonance imaging (MRI) to differentiate periapical lesions of endodontic origin and to compare the results with histopathological information. METHODOLOGY: The radiolucent periapical jaw lesions of 34 patients, which were surgically enucleated, were investigated by two radiologists using MRI, based on the same six criteria, to categorize the lesions as granulomas, radicular cysts or others. After apicoectomies, two oral pathologists (blinded to the radiologist's diagnoses) analysed all specimens by referring to seven specific parameters and diagnosed the specimens as granulomas, radicular cysts or other conditions. The inter-rater agreements between the radiologists and pathologists in terms of MRI and histological diagnoses, respectively, along with the discriminant power of the adopted criteria and the accuracy of the MRI assessments compared with the histopathological results, were calculated. Cohen's kappa test was adopted to examine inter-rater agreement between the two radiologists and two pathologists. Guttman's lambda coefficient (λ6 ) was used to evaluate the internal consistency of the items used for the differential diagnosis by radiologists. The accuracy resulted from a receiver operator characteristic (ROC) analysis. RESULTS: A strong inter-rater reliability was observed between the two radiologists (k-statistic = 0.86, P = 0.0001) and the two pathologists (k-statistic = 0.88, P = 0.0001). The internal consistency of the diagnostic items was 0.605 for cysts and 0.771 for granulomas. The accuracy (true positives plus true negatives) of the radiologists was greater than that of the pathologists based on analysis (area under the curve = 0.87 and 0.91, respectively). CONCLUSIONS: The reliability and accuracy of MRI were high and comparable to histopathological reliability, highlighting the usefulness of this noninvasive technique as a pre-treatment diagnostic method for periapical endodontic lesions.

Multimodular assessment of a calcified extraradicular deposit on the root surfaces of a mandibular molar.

AIM: To achieve a better understanding of a calcified extraradicular deposit on the apical root surfaces of a mandibular first molar associated with a radicular cyst and a sinus tract. A multimodular approach was applied using a combination of multiple investigation methods. SUMMARY: This case report presents a mandibular first molar with a calcified extraradicular deposit on the apical root surfaces of both roots. An apical periodontitis lesion was present and a sinus tract served as the only communication with the oral cavity. Diagnosis and treatment planning were based on clinical, radiographic (two- and three-dimensional) and ultrasound examination. The tooth was further analysed after extraction using microscopic imaging, nano-computed tomography (nano-CT), hard- and soft tissue histology and electron probe microanalysis. This multimodular approach revealed the calculus-like appearance and mineral composition of the extraradicular deposit. Multiple hypotheses about its aetiology are discussed. KEY LEARNING POINTS: Calcified extraradicular deposits can develop on the apical root surfaces of teeth with apical periodontitis in association with a radicular cyst and sinus tract. A sinus tract can serve as the only communication between the apical lesion and the oral cavity whilst no periodontal defects are present. The interplay of intra-oral radiography, high resolution CBCT, nano-CT, hard tissue histology and EPMA can reveal the calculus-like appearance and composition of the extraradicular deposit. Calcified extraradicular deposits appear hyperechoic on ultrasound imaging and can lead to the occurrence of twinkling artefacts due to their rough mineralized surface.

Increased interleukin 1α and interleukin 1ß expression is involved in the progression of periapical lesions in primary teeth.

BACKGROUND: Interleukin 1 (IL-1) is involved in bone resorption. However, the role of IL-1 in periapical lesions characterized by periapical bone destruction in primary teeth has not yet been fully elucidated. This study aimed to detect the distribution and expression of IL-1 in periapical lesions in primary teeth and assess the relationship between the cytokines and the degree of inflammatory cell infiltration. METHODS: A total of 106 chronic periapical lesions in primary teeth were harvested. Haematoxylin and eosin (H&E) staining was used to determine the histological type and the inflammatory cell infiltration grade (mild, moderate, and severe), and immunohistochemistry and enzyme-linked immunosorbent assay (ELISA) were used to detect the distribution and expression of IL-1α and IL-1ß. RESULTS: Of the 106 chronic periapical lesion samples, there were 85 cases of periapical granuloma, accounting for 80.19% of the total samples, and 21 cases of radicular cysts, accounting for 19.81%; no cases of abscess were detected. Immunohistochemistry results showed that both IL-1α and IL-1ß were expressed in periapical granulomas and cysts. ELISA results showed that IL-1α and IL-1ß levels were higher in the periapical granuloma group than in the radicular cyst and normal control groups (P < 0.05). In the periapical granuloma group, IL-1α and IL-1ß were detected at higher levels in the severe inflammatory cell infiltration subgroup than in the mild-inflammatory cell infiltration subgroup (P < 0.05), and IL-1ß expression was also higher in the moderate inflammatory cell infiltration subgroup than in the mild inflammatory cell infiltration subgroup (P < 0.01). A significant positive correlation was observed between the protein expression levels of IL-1α and IL-1ß and the inflammation grade in periapical granulomas from primary teeth (P < 0.05). CONCLUSION: Expression levels of the cytokines IL-1α and IL-1ß in periapical granulomas from primary teeth increased with increasing inflammatory severity and appeared to be a contributing factor to the progression of periapical lesions.

Participation of osteoclastogenic factors in immunopathogenesis of human chronic periapical lesions.

BACKGROUND: Chronic periapical lesions (CPLs) are common lesions of the oral cavity and are the result of caries, tooth fracture, iatrogenic causes, or factors causing contamination and pulp necrosis. Inflammatory cells participate in the expansion of CPLs by releasing factors that stimulate or inhibit osteolytic activity. The objective of this study was to investigate the participation of RANKL, TNF-α, cathepsin K, IL-33, and OPG in the development of radicular cysts (RCs) and periapical granulomas (PGs). METHODS: Paraffin-embedded sections of 30 RCs and 22 PGs were submitted to immunohistochemistry. RESULTS: Immunoexpression of the proteins studied was observed in the epithelium and capsule of RCs, as well as in connective tissue of PGs. The expression of the osteoclastogenic factors studied differed significantly in RCs and PGs (P < .001), with lower expression of OPG in RCs. In PGs, the lowest expression was observed for cathepsin K. Comparison of the 2 lesions showed a similar participation of RANKL and IL33, while a significant difference was observed for OPG (P < .001), TNF-α (P = .002), and cathepsin K (P = .016). No association of the expression of the proteins with lesions size was observed. CONCLUSIONS: This study demonstrated the participation of RANKL, TNF-α, IL-33, cathepsin K, and OPG in the development of RCs and PGs, with emphasis on the highest immunoreactivity of cathepsin in RCs and TNF-α and OPG in PGs. OPG possibly determines the slower growth of PGs compared to RCs.

Expression of podoplanin and TGF-beta in glandular odontogenic cyst and its comparison with developmental and inflammatory odontogenic cystic lesions.

BACKGROUND: The number of studies investigating the immunohistochemical characteristics of glandular odontogenic cysts (GOCs) is limited, due to its rarity. TGF-beta has been suggested to induce podoplanin expression in some lesions. We aimed to evaluate and compare podoplanin and TGF-beta expression in GOC and other odontogenic cystic lesions. METHODS: A total of 43 samples including five GOCs, 10 dentigerous cysts (DCs), eight unicystic ameloblastoma (UAs), and 20 radicular cysts (RCs) were selected and subjected to immunohistochemical staining using monoclonal antibodies against podoplanin and TGF-beta. Kruskal-Wallis test and Mann-Whitney U-test were used for statistical analysis along with Bonferroni for adjusting P-values (P < 0.05). RESULTS: Podoplanin immunoreactivity was observed in 80%, 70%, and 100% of DCs, RCs, and UAs, respectively, while none of the GOCs were positive for this marker (P = 0.004). Significant differences were only found in the GOC specimens. TGF-beta positivity occurred in the capsule and epithelium of all GOCs and DCs, while RCs and UAs demonstrated different expression percentages in the capsular and epithelial tissues. Epithelial TGF-beta showed significant differences among the studied lesions (P = 0.007) with the main difference found between DCs with RCs and DCs with UAs. CONCLUSIONS: Lack of podoplanin expression might be involved in the characteristic histologic and behavioral features of GOC, which seems to be unrelated to TGF-beta expression.

Analysis of tryptase-positive mast cells and immunoexpression of MMP-9 and MMP-13 in periapical lesions.

AIM: To evaluate the immunoexpression of tryptase, MMP-9 and MMP-13 in periapical lesions, correlating them with the type of lesion, intensity of the inflammatory infiltrate and thickness of the epithelial lining. METHODOLOGY: Twenty periapical granulomas (PGs), twenty radicular cysts (RCs) and twenty residual radicular cysts (RRCs) were submitted to immunohistochemical analysis using antitryptase, anti-MMP-9 and anti-MMP-13 antibodies. Immunoexpression of MMP-9 and MMP-13 was quantitatively evaluated both in the connective tissue of all lesions and in the epithelial lining of RCs and RRCs. Tryptase-positive mast cells were counted only in the connective tissue. The data were analysed using Kruskal-Wallis and Fisher's exact tests, as well as Spearman's correlation test (P < 0.05). RESULTS: In comparison with RCs and RRCs, PGs exhibited higher immunoexpression of tryptase, MMP-9 and MMP-13 (P = 0.002, P = < 0.001 and P < 0.001, respectively). In comparison with lesions with inflammatory infiltrates grades I and II, lesions with inflammatory infiltrate grade III had higher median percentages of MMP-13-positive cells (P = 0.003) and a tendency for higher expression of MMP-9 (P = 0.059). No significant difference was observed between the expression of the studied markers and epithelial thickness (P > 0.05). There were positive correlations between the number of tryptase-positive mast cells and the immunoexpression of MMP-9, as well as between the immunoexpression of MMP-9 and MMP-13. CONCLUSION: A larger number of tryptase-positive mast cells and greater enzymatic activity of MMP-9 and MMP-13 were found in PGs compared to RCs and RRCs. These findings are a characteristic of the dynamics of periapical diseases.

Immunoexpression of tumour necrosis factor-α, interleukin-1α and interleukin-10 on odontogenic cysts and tumours.

AIM: To analyse the immunoreactivity of IL-1α, TNF-α and IL-10 in odontogenic cysts and tumours and to investigate possible associations with established biological behaviours of these different lesions. METHODOLOGY: Immunohistochemical expression of anti-IL-1α, anti-TNF-α and anti-IL-10 antibodies was assessed on epithelium and mesenchyme of 20 radicular cysts (RCs), 20 residual cysts (RECs), 20 dentigerous cysts (DCs), 18 solid ameloblastomas (SAs), 20 keratocystic odontogenic tumours (KCOTs) and 15 dental follicles (DFs). Comparative analysis of data was performed using the nonparametric Wilcoxon signed-rank test and Kruskal-Wallis's test. RESULTS: Significantly greater expression of IL-1α in the epithelium was noted in RC, KCOT and SA (P = 0.01), whilst IL-10 and TNF-α was in the epithelium of RC, DC and KCOT (P < 0.01). In the mesenchyme, significantly greater immunopositivity was observed for IL-1α, IL-10 and TNF-α in KCOT, DC and RC (P < 0.01). In epithelial and mesenchymal tissues, there were a significant number of cases of RC and DC with IL-1α < IL-10 ratio (P < 0.01), whilst SA and KCOT showed IL-1α > IL-10 (P < 0.01). There was a significantly greater percentage of DF, DC and KCOT with TNF-α > IL10 ratio (P < 0.01). CONCLUSION: These results suggest involvement of the proteins in the pathogenesis of odontogenic cysts and tumours, with emphasis on the highest immunoreactivity of osteolysis stimulating factors in tumours with aggressive biological behaviour, such as SA and KCOT.

Expression of the stem cell factor in fibroblasts, endothelial cells, and macrophages in periapical tissues in human chronic periapical diseases.

Stem cell factor (SCF), an important stem cell cytokine, has multiple functions. Fibroblasts (FBs), mature mast cells, endothelial cells (ECs), and eosinophil granulocytes can produce SCF in the inflammatory process. Therefore, we aimed to observe SCF expression in FBs, ECs, and macrophages (MPs) in periapical tissues in human chronic periapical disease and investigate the effects of cells expressing SCF in pathogenesis of the disease. Healthy (N = 20), periapical cyst (N = 15), and periapical granuloma (N = 15) tissues were fixed in 10% formalin for 48 h, embedded in paraffin, and stained with hematoxylin and eosin to observe histological changes. SCF expression was observed in FBs, ECs, and MPs in periapical tissues by double immunofluorescence. CD334, CD31, and CD14 are specific markers of FBs, ECs, and MPs, respectively. Results showed that densities of CD334-SCF double-positive FBs, CD31-SCF double-positive ECs, and CD14-SCF double-positive MPs were significantly increased in periapical tissue groups (P < 0.01). There were no significant differences in CD334-SCF double-positive FB and CD31-SCF double-positive EC levels between the two periapical tissue groups (P > 0.05). CD14-SCF double-positive MP density was considerably higher in periapical granulomas than in cysts (P < 0.01). FB, EC, and MP levels were significantly high and densities of CD334-SCF double-positive FBs, CD31-SCF double-positive ECs, and CD14-SCF double-positive MPs improved considerably in chronic periapical tissues, suggesting that the cells might be related to occurrence, development, and pathogenesis of chronic periapical disease.

Expression of interleukin-33 and its receptor ST2 in periapical granulomas and radicular cysts.

BACKGROUND: Interleukin-33 (IL-33) is a recently identified cytokine belonging to the IL-1 family and ligand for the IL-1 receptor-related protein ST2. IL-33/ST2 signaling plays a critical role in allergy, autoimmunity, and chronic inflammatory disorders, but its role in the pathogenesis of periapical lesions is unknown. We aimed to investigate the expression patterns of IL-33 and ST2 in human periapical lesions. METHODS: Periapical lesions (n = 36) and healthy periapical tissues (n = 10) were evaluated by immunohistochemistry using antibodies specific for human IL-33 and ST2. Lesion samples were further analyzed by double immunofluorescence to assess IL-33/ST2 co-expression. RESULTS: The numbers of IL-33- and ST2-positive fibroblasts were significantly higher in periapical lesions compared to healthy periapical tissues (both P < 0.05), while the numbers of IL-33- and ST2-positive endothelial cells were similar (both P > 0.05). There were no significant differences in the numbers of IL-33- and ST2-positive fibroblasts and endothelial cells between periapical granulomas and radicular cysts (all P > 0.05). Similarly, numbers of ST2-positive mononuclear cells did not differ between periapical granulomas and radicular cysts (P > 0.05). The majority of epithelial cells in radicular cysts were IL-33 positive, while the small proportion of epithelial cells was ST2 positive. Double immunofluorescence analysis revealed IL-33/ST2 co-expression in fibroblasts and endothelial cells. CONCLUSIONS: IL-33 and ST2 are expressed in periapical granulomas and radicular cysts. Increased numbers of IL-33- and ST2-positive fibroblasts in periapical lesions when compared to healthy periapical tissues suggest that IL-33/ST2 signaling may be involved in periapical inflammation and tissue fibrosis.

BRAFV600E mutation in the diagnosis of unicystic ameloblastoma.

BACKGROUND: Unicystic ameloblastoma, an odontogenic neoplasm, presents clinical and radiographic similarities with dentigerous and radicular cysts, non-neoplastic lesions. It is not always possible to reach a final diagnosis with the incisional biopsy, leading to inappropriate treatment. The BRAFV600E activating mutation has been reported in a high proportion of ameloblastomas. The purpose of the study was to assess the utility of the detection of the BRAFV600E mutation in the differential diagnosis of unicystic ameloblastoma with dentigerous and radicular cysts. METHODS: Twenty-six archival samples were included, comprising eight unicystic ameloblastomas (UAs), nine dentigerous and nine radicular cysts. The mutation was assessed in all samples by anti-BRAFV600E (clone VE1) immunohistochemistry (IHC) and by TaqMan mutation detection qPCR assay. Sanger sequencing was further carried out when samples showed conflicting results in the IHC and qPCR. RESULTS: Although all UAs (8/8) showed positive uniform BRAFV600E staining along the epithelial lining length, the mutation was not confirmed by qPCR and Sanger sequencing in three samples. Positive staining for the BRAFV600E protein was observed in one dentigerous cyst, but it was not confirmed by the molecular methods. Furthermore, 2/9 dentigerous cysts and 2/9 radicular cysts showed non-specific immunostaining of the epithelium or plasma cells. None of the dentigerous or radicular cysts cases presented the BRAFV600E mutation in the qPCR assay. CONCLUSIONS: The BRAFV600E antibody (clone VE1) IHC may show non-specific staining, but molecular assays may be useful for the diagnosis of unicystic ameloblastoma, in conjunction with clinical, radiological and histopathological features.