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35 p.-2 tab.-4 fig.Este artículo no presenta el mismo título en el preprint adjunto ("Porphyromonas gingivalis K1 and K2 serotypes are associated with periodontitis"), Aim: Destructive periodontitis is associated with a Th1-Th17-dominated immune response and the Porphyromonas gingivalis K1 and K2 serotypes induce a strong Th1-Th17 response. This study aimed to investigate whether these P. gingivalis serotypes were associated with bone resorption and periodontitis. Materials and Methods: The RANKL production and TRAP+ osteoclast induction were quantified when naïve-T-lymphocytes were stimulated with dendritic cells primed with the P. gingivalis serotypes. The T-bet, GATA-3, RORC2, and Foxp3 expression was correlated with RANKL production. The frequency of proliferating memory-Tlymphocytes in response to P. gingivalis serotypes was determined in both periodontitis and healthy subjects. Results: T-lymphocytes stimulated by K1 or K2-primed dendritic cells elicited higher levels of RANKL and TRAP+ osteoclasts than cells stimulated with the other serotypes. RANKL positively correlated with RORC2. Upon K1 or K2 stimulation, higher frequency of responding memory-T-lymphocytes was detected in periodontitis patients than controls. Upon K4 or K- stimulation, higher frequency of responding memory-Tlymphocytes was detected in healthy subjects. Conclusions: P. gingivalis serotypes K1 and K2 are associated with bone resorption through the increased RANKL production and TRAP+ osteoclast induction. Due to their association with higher frequency of memory-T-lymphocytes in periodontitis patients, these serotypes could be involved in the pathogenesis of periodontitis., The research in our lab-oratories has been supported by grants from the Spanish Ministry of Science and Technology (SAF2009-07974), Instituto de Salud Carlos III (RD06/0010/1010),Spanish National Research Council (PIE200420E240 and PIE200420E586) and Chilean Government (FONDECYT 11100298).

8 páginas, 5 figuras, 2 tablas -- PAGS nros. 396-403, Aim: T regulatory (Treg) cells have been detected in periodontitis lesions, and forkhead box P3 (Foxp3) expression has been negatively correlated to receptor activator of nuclear factor-κ B ligand (RANKL). The aim of this study was to correlate T-helper type 1 (Th1), Th2, Th17 and Treg transcription factor expressions, in gingival tissues from patients undergoing active periodontal tissue destruction, with bone loss-associated cytokines. Materials and Methods: In 10 chronic periodontitis patients undergoing disease progression, the mRNA expressions of T-bet, GATA-3, Foxp3, RORC2, interleukin (IL)-1β, IL-10, IL-17, RANKL, interferon (IFN)-γ and transforming growth factor (TGF)-β1 were quantified using real-time reverse transcription-polymerase chain reaction. The levels of these markers were compared between active and inactive periodontal lesions. Results: In active periodontal lesions, Foxp3, T-bet, RANKL, IL-17, IL-1β and IFN-γ were significantly over-expressed compared with inactive lesions. The expression of IFN-γ was the highest within the active periodontal lesions, similar to that of TGF-β1 within the inactive ones. There was a positive correlation between RANKL and IL-17. Additionally, RANKL and IL-17 were positively correlated with RORC2, but no correlation was detected with Foxp3. Conclusions: These results lead us to speculate that Foxp3+ cells that do not have a regulatory function might have a role in the pathogenesis of active periodontal lesions by down-regulating TGF-β1 and IL-10 synthesis that lead to the over-expression of Th17-associated cytokines RANKL and IL-17

9 páginas, 4 figuras, 1 tabla -- PAGS nros. 689-697, Background and Objective: Dendritic cells are able to prime and polarize naïve T cells towards either a T helper 1 or a T helper 2 response, depending on the antigen type and concentration, the costimulatory signals and the local cytokine millieu. In this investigation, we analyzed the response of human dendritic cells to stimulation with different concentrations of Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans. Material and Methods: Using different concentrations of P. gingivalis ATCC 33277 and A. actinomycetemcomitans ATCC 33384, we determined the expression of the maturation markers CD80 and CD86 from purified human dendritic cells by flow cytometry. We also evaluated the mRNA expression levels for the cytokines interleukin-1β, interleukin-2, interleukin-5, interleukin-6, interleukin-10, interleukin-12, interleukin-13, interferon-γ, tumor necrosis factor-α and tumor necrosis factor-β by quantitative real-time reverse transcription–polymerase chain reaction. Results: Both P. gingivalis and A. actinomycetemcomitans led to dendritic cell maturation, but the expression of CD80 was higher when the dendritic cells were stimulated with A. actinomycetemcomitans. Although both pathogens induced a T helper 1 pattern of cytokine expression, A. actinomycetemcomitans-stimulated dendritic cells expressed interleukin-1β, interleukin-12, interferon-γ, tumor necrosis factor-α and tumor necrosis factor-β at lower bacterial concentrations than P. gingivalis. While 106 bacteria/mL of P. gingivalis or 104 bacteria/mL of A. actinomycetemcomitans induced expression of interleukin-12p40, the expression of other cytokines required 10 to 100-fold higher concentrations of bacteria. Conclusion: These results demonstrate that A. actinomycetemcomitans is a more potent immunogen than P. gingivalis because, at least in vitro, it induces stronger differentiation and activation of dendritic cells. In addition, our data also show that for a given strain, the bacterial load determines the pattern of cytokines that are expressed, The work in the author’s laboratories has been supported by grant from the Spanish Ministry of Health (FIS-060181 to MS), Spanish Ministry of Science and Education (SAF2006-4826 and SAF2006-04903 to AS and JAGS, respectively) and Chilean Government (CONICYT-26080046 to RV)

7 páginas, 3 figuras, 3 tablas -- PAGS nros. 283-289, OBJECTIVES: The cytokine receptor activator of nuclear factor kappaB-ligand (RANKL) has been involved in both the physiological and pathological regulation of osteoclast life span and bone metabolism. Periapical granuloma is a periradicular lesion characterized by periapical bone destruction. The aims of this study were to associate the RANKL mRNA levels to periapical granulomas using the real-time reverse transcriptase-polymerase chain reaction (RT-PCR) technique and to determine the specific cell involved in RANKL synthesis. METHODS: In eight periapical granuloma and eight periodontal ligament samples from periodontally healthy volunteers, RANKL mRNA was detected by real-time RT-PCR. Expression of RANKL on infiltrate leukocytes was further investigated by flow cytometry in six periapical granulomas. RESULTS: Receptor activator of nuclear factor kappaB-ligand mRNA levels were higher in periapical granulomas than in healthy periodontal ligament as its RANKL mRNA cycle threshold (Ct) and DeltaCt were significantly lower than that of controls (33.07 +/- 1.24 vs 36.96 +/- 1.69 and 11.58 +/- 3.02 vs 15.60 +/- 3.31, respectively). A 16.2-fold (2.0-131.6) higher RANKL gene expression was detected in the granulomas compared with the control tissues. We determined by flow cytometry that lymphocytes were the predominant leukocyte cells (53.31%), and monocytes and dendritic cells were the main RANKL synthesizers in granuloma lesions. CONCLUSIONS: These data indicate that monocytes synthesized RANKL in periapical granulomas and suggest that RANKL is involved in bone loss associated with periapical lesions, This research was supported by grant 1050518 of Fondo de Investigación Científica y Tecnológica (FONDECYT), grant 01/0073-01 of Fondo de Investigaciones Sanitarias (FIS), and grant PG/2503 of Vicerrectoría Académica y Departamento de Posgrado y Postítulo of Universidad de Chile. The authors are grateful to Dr Raúl Sáez from Dental Service of Barros Luco Hospital