Immunohistochemical study of alpha-smooth muscle actin in odontogenic cysts and tumors

Abstract

Context:Myofibroblasts (MFs) are fibroblasts with smooth muscle-like features characterized by the presence of a contractile apparatus. Alpha-smooth muscle actin (α-SMA) is the actin isoform that predominates within vascular smooth muscle cells and plays an important role in fibrogenesis. MFs are metabolically and morphologically distinctive fibroblasts expressing α-SMA, and their activation plays a key role in development of the fibrotic response.Aims and Objectives:The aim of this study is to demonstrate the frequency, distribution and expression of α-SMA-positive MFs in odontogenic keratocyst (OKC), dentigerous cyst (DC) and ameloblastoma and correlate it to their aggressive biological behavior.Settings and Design:A retrospective study of 45 diagnosed cases, which includes 15 cases of OKC, 15 cases of DC and 15 cases of ameloblastoma, was undertaken to demonstrate expression of α-SMA retrieved from archives of our department.Materials and Methods:α-SMA mouse anti-human antibody and horseradish peroxidase detection system were used in this study.Statistical Analysis:Descriptive statistical analysis and ANOVA test were used for statistical analysis.Results:The difference in mean α-SMA count was found to be statistically significant between ameloblastoma and DC group (P < 0.001) as well as OKC and DC group (P < 0.001). No significant difference is observed between ameloblastoma and OKC group (P > 0.05). Results showed that mean number of stromal MFs in OKC and ameloblastoma were significantly higher than DC.Conclusion:The present study has shown that the mean number of MFs was higher in OKC and ameloblastoma, while the mean number of MFs in DC was quite low and significantly different from that of ameloblastoma and OKC.

Myofibroblasts and increased angiogenesis contribute to periapical cystic injury containment and repair

“…MFs are transdifferentiated fibroblasts and the beta growth transforming factor (TGF-β) cytokine plays an important role in directly promoting their development by inducing α-SMA expression ( 10 , 16 - 17 ). This actin isoform predominates in vascular smooth muscle cells and its activation plays an important role in fibrotic response ( 18 ).…”

“…Thereby controlling lesion growth and vascular support through angiogenesis ( 10 , 16 ). Unfortunately, few studies on the presence of MF in odontogenic cysts are available ( 2 , 5 , 10 , 18 - 23 ) and only four address inflammatory odontogenic lesions ( 16 - 17 , 24 - 25 ).…”

“…A statistically significant difference between the presence of MF in the RCs and RRCs was observed, with higher concentrations in RRC. It is believed that the presence of MFs is essential in the physiological construction of scar processes, due to their ability to produce collagen, which may be associated to lesion growth and progression ( 18 ).…”

Análise imuno-histoquímica de Ki-67 e α-SMA em ceratocisto odontogênico, ameloblastoma e folículo pericoronário

“…A ativação de MF no estroma das lesões também deve ser considerada no potencial de crescimento e desenvolvimento das mesmas 12 . Neste estudo, a presença de MF foi avaliada pela expressão de α-SMA e esta foi maior em casos de CO, em relação a AM e FP.…”

“…Os MFs são fibroblastos que possuem características semelhantes às de músculo liso, com capacidade contrátil devida à elevada expressão de α-SMA 11 . Os MFs, além de produzirem colágeno, têm o potencial de facilitar a progressão de lesões epiteliais neoplásicas, podendo também favorecer o crescimento de cistos e tumores odontogênicos 12 .…”