Stromal myofibroblasts in focal reactive overgrowths of the gingiva

Abstract

Focal reactive overgrowths are among the most common oral mucosal lesions. The gingiva is a significant site affected by these lesions, when triggered by chronic inflammation in response to microorganisms in dental plaque. Myofibroblasts are differentiated fibroblasts that actively participate in diseases characterized by tissue fibrosis. The objective of this study was to evaluate the presence of stromal myofibroblasts in the main focal reactive overgrowths of the gingiva: focal fibrous hyperplasia (FFH), peripheral ossifying fibroma (POF), pyogenic granuloma (PG), and peripheral giant cell granuloma (PGCG). A total of 10 FFHs, 10 POFs, 10 PGs, and 10 PGCGs from archival specimens were evaluated. Samples of gingival mucosa were used as negative controls for stromal myofibroblasts. Oral squamous cell carcinoma samples, in which stromal myofibroblasts have been previously detected, were used as positive controls. Myofibroblasts were identified by immunohistochemical detection of alpha smooth muscle actin (α-sma). Myofibroblast immunostaining was qualitatively classified as negative, scanty, or dense. Differences in the presence of myofibroblasts among FFH, POF, PG, and PGCG were analyzed using the Kruskal-Wallis test. Stromal myofibroblasts were not detected in FFH, POF, PG, or PGCG. Consequently, no differences were observed in the presence of myofibroblasts among FFH, POF, PG, or PGCG (p > 0.05). In conclusion, stromal myofibroblasts were not detected in the focal reactive overgrowths of the gingiva that were evaluated, suggesting that these cells do not play a significant role in their pathogenesis.

Myofibroblasts and Transforming Growth Factor-Beta1 in Reactive Gingival Overgrowths

“…This finding could be explained by the small number of cases in previous studies and differences in the immunohistochemical procedure. The findings of the present study regarding OFE are in accordance to a previous study by Garcia de Marcos et al [14] that reported the presence of MFs positive for vimentin and alpha-SMA, whereas, Damasceno et al [15] did not reveal the presence of MFs. The results of our study suggest that MFs may contribute in the formation of collagenous connective tissue more frequently in OFE than in FE.…”

“…In the current study the detection of MFs was based on the combined immunohistochemical profile (vimentin and alpha-SMA) as well as their morphology indicating that MFs of FE and OFE belong to the VA type. Interestingly, the presence of MFs in FE has not been reported in previous studies [13,15]. This finding could be explained by the small number of cases in previous studies and differences in the immunohistochemical procedure.…”

miR-218 regulates focal adhesion kinase–dependent TGFβ signaling in fibroblasts

“…Scarring, a natural response to wounding in adult tissue, including skin, does not occur in the oral cavity (Schor et al ., 1996). Instead of a fibrocontractile response characterized by the presence of abundant α-smooth muscle actin (SMA)–containing myofibroblasts, the fibrotic response in oral tissue is principally fibroproliferative and is largely devoid of myofibroblasts (Sakamoto et al ., 2002; Martelli et al ., 2010; Damasceno et al ., 2012). Understanding why gingiva and skin behave differently in response to fibrotic stimuli should yield valuable insights into how to achieve scarless repair.…”

Cellular proliferation markers in peripheral and central fibromas: a comparative study

“…Nevertheless, the peripheral ossifying fibroma (PEOF) is a condition of the inflammatory reactive nature associated with mineralization and derived from the periodontal ligament cells. Dental calculus, plaque, dental appliances, ill-fitting crows and rough restorations are considered to be local irritants 7,9 . Local surgical excision is the most common treatment for PEOF and the recurrence rate is approximately 16.0% 7 .…”

“…The NOR are associated with acidic argyrophilic non-histonic proteins which can be viewed through the AgNOR technique 20,24 . Studies have applied this technique as a useful method to evaluate the differences among cellular proliferation indexes in non-neoplastic reactive lesions, as well as in benign or malignant neoplasms 3,9,15,17,23 .…”