Association between genetic polymorphisms in rank, rankl and opg and peri-implant diseases in patients from the Amazon Region

Abstract The present study evaluated polymorphisms in RANK, RANKL and OPG-encoding genes to assess whether they are associated with mucositis and peri-implantitis in a population from the Brazilian Amazon region. One hundred and fourteen patients with dental implants were included in the study. After clinical and radiographic examination, the sample was categorized into 4 groups, according to the peri-implant status: Healthy (n=71), Mucositis (n=30), Peri-implantitis (n=13) and Diseased (Mucositis + Peri-implantitis, n=43). Genomic DNA was extracted from buccal cells from saliva, and the genetic polymorphism in osteoprotegerin (OPG), Kappa nuclear factor activator receptor (RANKL) and nuclear kappa factor activator receptor (RANK) were genotyped by the real time PCR. Univariate and multivariate statistical analyses were performed to compare clinical variables among groups and to evaluate genotypes and alleles distributions and the established alpha was 5%. Age, peri-implant biotype, diabetes and presence of peri-implant biofilm were associated with mucositis (p<0.05) and peri-implantitis (p<0.05). Smoking, alcoholism, and periodontal biofilms were also associated with the presence of peri-implantitis (p<0.05). Univariate and multivariate analysis did not demonstrate an association of peri-implantitis or mucositis with any genetic polymorphism in RANK (rs3826620), RANKL (rs9594738) and OPG (rs2073618) (p>0.05). The studied genetic polymorphism in RANK, RANKL and OPG were not associated with mucositis and peri-implantitis in a Brazilian population from the Amazon region.

Resumo O presente estudo avaliou a associação da predisposição clínica e dos fatores genéticos com a presença de doenças peri-implantares. Cento e quatorze pacientes com implantes dentais instalados na Clínica de Especialização do Amazonas, Brazil, foram incluidos no estudo. Após exame clínico e radiográfico, a amostra foi categorizada em 4 grupos, de acordo com o Status peri-implantar: saúde (n=71), mucosite (n=30), peri-implantite (n=13) e doentes (mucosite + peri-implantite). DNA genômico foi extraído de células orais da saliva, e o polimorfismo genético em osteoprotegerina (OPG), ligante do receptor ativador do fator Kappa nuclear (RANKL) e receptor ativador do fator Kappa nuclear (RANK) foram genotipados por PCR em tempo real. O estudo se propôs a avaliar se os polimorfismos em RANK, RANKL e OPG estão envolvidos na patogênese da mucosite e da peri-implantite, e avaliar também a presença de fatores de risco moduladores da resposta em uma população brasileira. Idade, biotipo peri-implantar, diabetes e presença de biofilme peri-implantar foram associados a mucosite (p<0.05) e peri-implantite (p<0.05). Tabagismo, alcoolismo e biofilme periodontal também foram associados com a presença de peri-implantite (p<0.05). Análise univariada e multivariada não demonstraram associação de peri-implantite ou mucosite com os polimorfismos genéticos em RANK (rs3826620), RANKL (rs9594738) e OPG (rs2073618) (p>0.05). Os polimorfismos genéticos estudados não foram associados com mucosite e peri-implantite em uma população brasileira da região Amazônica.

RANK/RANKL/OPG Expression in Rapid Maxillary Expansion

Abstract The aim of this study was to evaluate osteoclastogenesis signaling in midpalatal suture after rapid maxillary expansion (RME) in rats. Thirty male Wistar rats were randomly assigned to two groups with 15 animals each: control (C) and RME group. RME was performed by inserting a 1.5-mm-thick circular metal ring between the maxillary incisors. The animals were euthanized at 3, 7 and 10 days after RME. qRT-PCR was used to evaluate expression of Tnfsf11 (RANKL), Tnfrsf11a (RANK) and Tnfrsf11b (OPG). Data were submitted to statistical analysis using two-way ANOVA followed by Tukey test (a=0.05). There was an upregulation of RANK and RANKL genes at 7 and 10 days and an upregulation of the OPG gene at 3 and 7 days of healing. Interestingly, an increased in expression of all genes was observed over time in both RME and C groups. The RANKL/OPG ratio showed an increased signaling favoring bone resorption on RME compared to C at 3 and 7 days. Signaling against bone resorption was observed, as well as an upregulation of OPG gene expression in RME group, compared to C group at 10 days. The results of this study concluded that the RANK, RANK-L and OPG system participates in bone remodeling after RME.

Resumo O objetivo deste estudo foi avaliar a sinalização osteoclastogenese na sutura palatina após a expansão rápida da maxila (ERM) em ratos. Um total de 30 ratos Wistar machos foram divididos aleatoriamente em dois grupos com 15 animais cada: controle (C) e grupo ERM. ERM foi realizada através da inserção de um anel de metal circular de 1,5 mm de espessura entre os incisivos superiores. Os animais foram sacrificados aos 3, 7 e 10 dias após a RME. qRT-PCR foi utilizado para avaliar a expressão de Tnfsf11 (RANKL), Tnfrsf11a (RANK) e TNFRSF11b (OPG). Os dados foram submetidos à análise de variância de duas vias, seguido pelo teste de Tukey (a=0,05). Houve uma regulação positiva de genes RANK e RANKL aos 7 e 10 dias e uma regulação positiva do gene OPG aos 3 e 7 dias de tratamento. Curiosamente, foi observado um aumento na expressão de todos os genes ao longo do tempo nos grupos ERM e C. O RANKL/OPG mostrou um aumento na sinalização favorecendo a reabsorção óssea no ERM em comparação com o C nos períodos de 3 e 7 dias. Foi observada uma sinalização contra a reabsorção óssea, assim como, uma regulação favorável da expressão do gene OPG no grupo ERM, comparado ao grupo C aos 10 dias. Os resultados deste estudo permitem concluir que o sistema RANK, RANK-L e OPG participa de remodelação óssea após a ERM.

Inhibitory effects of osteoprotegerin on osteoclast formation and function under serum-free conditions

The purpose of this study was to determine whether osteoprotegerin (OPG) could affect osteoclat differentiation and activation under serum-free conditions. Both duck embryo bone marrow cells and RAW264.7 cells were incubated with macrophage colony stimulatory factor (M-CSF) and receptor activator for nuclear factor kappaB ligand (RANKL) in serum-free medium to promote osteoclastogenesis. During cultivation, 0, 10, 20, 50, and 100 ng/mL OPG were added to various groups of cells. Osteoclast differentiation and activation were monitored via tartrate-resistant acid phosphatase (TRAP) staining, filamentous-actin rings analysis, and a bone resorption assay. Furthermore, the expression osteoclast-related genes, such as TRAP and receptor activator for nuclear factor kappaB (RANK), that was influenced by OPG in RAW264.7 cells was examined using real-time polymerase chain reaction. In summary, findings from the present study suggested that M-CSF with RANKL can promote osteoclast differentiation and activation, and enhance the expression of TRAP and RANK mRNA in osteoclasts. In contrast, OPG inhibited these activities under serum-free conditions.

RANKL stimulates proliferation, adhesion and IL-7 expression of thymic epithelial cells

Abstract In many clinical situations which cause thymic involution and thereby result in immune deficiency, T cells are the most often affected, leading to a prolonged deficiency of T cells. Since only the thymic-dependent T cell production pathway secures stable regeneration of fully mature T cells, seeking strategies to enhance thymic regeneration should be a key step in developing therapeutic methods for the treatment of these significant clinical problems. This study clearly shows that receptor activator of NF-kappaB ligand (RANKL) stimulates mouse thymic epithelial cell activities including cell proliferation, thymocyte adhesion to thymic epithelial cells, and the expression of cell death regulatory genes favoring cell survival, cell adhesion molecules such as ICAM-1 and VCAM-1, and thymopoietic factors including IL-7. Importantly, RANKL exhibited a significant capability to facilitate thymic regeneration in mice. In addition, this study demonstrates that RANKL acts directly on the thymus to activate thymus regeneration regardless of its potential influences on thymic regeneration through an indirect or systemic effect. In light of this, the present study provides a greater insight into the development of novel therapeutic strategies for effective thymus repopulation using RANKL in the design of therapies for many clinical conditions in which immune reconstitution is required.