RESUMO
Aging may negatively affect gingival wound-healing. However, little is known about the mechanisms underlying this phenomenon. The present study examined the cellular responses associated with gingival wound-healing in aging. Primary cultures of human gingival fibroblasts were obtained from healthy young and aged donors for the analysis of cell proliferation, cell invasion, myofibroblastic differentiation, and collagen gel remodeling. Serum from young and old rats was used to stimulate cell migration. Gingival repair was evaluated in Sprague-Dawley rats of different ages. Data were analyzed by the Mann-Whitney and Kruskal-Wallis tests, with a p value of .05. Fibroblasts from aged donors showed a significant decrease in cell proliferation, migration, Rac activation, and collagen remodeling when compared with young fibroblasts. Serum from young rats induced higher cell migration when compared with serum from old rats. After TGF-beta1 stimulation, both young and old fibroblasts demonstrated increased levels of alpha-SMA. However, alpha-SMA was incorporated into actin stress fibers in young but not in old fibroblasts. After 7 days of repair, a significant delay in gingival wound-healing was observed in old rats. The present study suggests that cell migration, myofibroblastic differentiation, collagen gel remodeling, and proliferation are decreased in aged fibroblasts. In addition, altered cell migration in wound-healing may be attributable not only to cellular defects but also to changes in serum factors associated with the senescence process.
Assuntos
Envelhecimento/fisiologia , Gengiva/fisiologia , Actinas/efeitos dos fármacos , Envelhecimento/patologia , Animais , Diferenciação Celular/fisiologia , Movimento Celular/fisiologia , Proliferação de Células , Sobrevivência Celular/fisiologia , Células Cultivadas , Colágeno/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Fibroblastos/patologia , Fibroblastos/fisiologia , Gengiva/patologia , Gengivectomia/métodos , Humanos , Miofibroblastos/patologia , Miofibroblastos/fisiologia , Ratos , Ratos Sprague-Dawley , Fator de Crescimento Transformador beta1/farmacologia , Cicatrização/fisiologia , Proteínas rac de Ligação ao GTP/análiseRESUMO
BACKGROUND AND OBJECTIVE: Statins have been used to control hypercholesterolemia. However, these drugs also exert pleiotropic effects that include the modulation of inflammation and cell signaling. The present study has analyzed the effects of simvastatin on several cell responses involved in tissue repair, including cell adhesion, cell migration and invasion, actin cytoskeleton remodeling and cell viability. MATERIAL AND METHODS: Primary cultures of gingival fibroblasts were stimulated with simvastatin. Cell adhesion was evaluated using a colorimetric assay. Cell spreading was evaluated microscopically. Cell migration and invasion were assessed using a scratch wound-healing assay and a bicameral cell culture system, respectively. Changes in actin cytoskeleton and focal adhesion assembly were evaluated through immunofluorescence for actin, vinculin and active ß1 integrin. Rac activation was evaluated by means of a pull-down assay. Cell viability was assessed using a colorimetric assay that determines mitochondrial functionality. Data analysis was performed using the Mann-Whitney U-test. RESULTS: Simvastatin diminished cell adhesion and spreading over a fibronectin matrix. It also altered the closure of scratch wounds induced on cell monolayers and cell invasion through a Transwell system. Simvastatin-treated cells displayed an altered lamellipodia with poorly developed focal adhesion contacts and reduced levels of ß1 integrin activation. During cell spreading, simvastatin diminished Rac activation. CONCLUSION: The present study shows that simvastatin may alter cell migration by disrupting the cell signaling networks that regulate the actin cytoskeleton dynamics. This mechanism may affect the response of gingival mesenchymal cells during wound healing.
Assuntos
Anticolesterolemiantes/farmacologia , Fibroblastos/efeitos dos fármacos , Gengiva/efeitos dos fármacos , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Sinvastatina/farmacologia , Actinas/análise , Adolescente , Adulto , Adesão Celular/efeitos dos fármacos , Técnicas de Cultura de Células , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Citoesqueleto/efeitos dos fármacos , Ativação Enzimática , Feminino , Imunofluorescência , Gengiva/citologia , Humanos , Integrina beta1/análise , Masculino , Pseudópodes/efeitos dos fármacos , Vinculina/análise , Adulto Jovem , Proteínas rac de Ligação ao GTP/análiseRESUMO
RAC3 has been firstly characterized as a nuclear receptor coactivator that is found in limited amounts in normal cells, but is over-expressed in tumors and is also an NF-kB coactivator. Although the mechanisms involved in its over-expression are not clear, it is well known that it enhances resistance to apoptosis. In this work, we investigated if there are any additional mechanisms by which RAC3 may contribute to tumor development and if TNF-a, an inflammatory cytokine that is found at high levels in cancer could increase RAC3 levels. We found that enhancement of RAC3 levels by transfection of HEK293 cells with a RAC3 expression vector induces a significant increase of cell proliferation not only in the presence, but also in the absence of serum growth factors. Moreover, the cells were transformed showing an anchorage independent growth, similar to that observed in tumoral cells. The treatment of HEK293 cells with TNF-a induced an increase in the protein levels of RAC3 and this was blocked by an NF-kB specific inhibitor, suggesting that this transcription factor is involved in the cytokine effect. We conclude that RAC3, in addition to is anti-apoptotic action, is a transforming factor that promotes the proliferation and growth independent of anchorage, and that its levels could be elevated by the action of inflammatory cytokines that are involved in the anti-tumoral response.