Asaf Wilensky

Hebrew University of Jerusalem, Yerushalayim, Jerusalem District, Israel

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Publications (26)74.62 Total impact

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    ABSTRACT: Cysteine proteases (gingipains) from Porphyromonas gingivalis are key virulence factors in chronic periodontitis. Innate immune receptors CD14, Toll-like receptor (TLR) 2 and TLR4 are important in P. gingivalis recognition. We examined the ability of gingipains to cleave CD14, TLR2 and TLR4, and the consequences for the cellular response to bacterial challenge. Macrophages were exposed to Arg (RgpA and RgpB)- and Lys (Kgp)-gingipains, and residual expression of TLR2, TLR4 and CD14 was determined by flow cytometry. The cellular response to live bacteria following exposure to purified gingipains was evaluated by TNFα production and bacterial phagocytosis. RgpA and Kgp decreased CD14 detection in a concentration (p = 0.0000002)- and time (p = 0.03)-dependent manner, whereas RgpB had no significant effect. TLR2 and TLR4 expression were unaffected. Reduction in CD14 expression was more efficient with Lys-gingipain than with Arg-gingipain. A reduced CD14 surface level correlated with decreased TNFα secretion and bacterial phagocytosis following challenge with live P. gingivalis, but the response to heat-killed bacteria was unaffected. Therefore, gingipains reduce CD14 expression without affecting expression of the bacterial-sensing TLRs. Reduced CD14 expression depends on the gingipain hemagglutinin/adhesion site and results in macrophage hyporesponsiveness to bacterial challenge. Further studies are needed to determine if reduced CD14 expression is linked to periodontitis induced by P. gingivalis. © 2014 S. Karger AG, Basel.
    Journal of Innate Immunity 09/2014; · 4.46 Impact Factor
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    ABSTRACT: Periodontal infection (Periodontitis) is a chronic inflammatory disease, which results in the breakdown of the supporting tissues of the teeth. Previous epidemiological studies have suggested that resistance to chronic periodontitis is controlled to some extent by genetic factors of the host. The aim of this study was to determine the phenotypic response of inbred and Collaborative Cross (CC) mouse populations to periodontal bacterial challenge, using an experimental periodontitis model. In this model, mice are co-infected with Porphyromonas gingivalis and Fusobacterium nucleatum, bacterial strains associated with human periodontal disease. Six weeks following the infection, the maxillary jaws were harvested and analyzed for alveolar bone loss relative to uninfected controls, using computerized microtomography (microCT). Initially, four commercial inbred mouse strains were examined to calibrate the procedure and test for gender effects. Subsequently, we applied the same protocol to 23 lines (at inbreeding generations 10--18) from the newly developed mouse genetic reference population, the Collaborative Cross (CC) to determine heritability and genetic variation of control bone volume prior to infection (CBV, naive bone volume around the teeth of uninfected mice), and residual bone volume (RBV, bone volume after infection) and loss of bone volume (LBV, the difference between CBV and RBV) following infection RESULTS: BALB/CJ mice were highly susceptible (P<0.05) whereas DBA/2J, C57BL/6J and A/J mice were resistant. Six lines of the tested CC population were susceptible, whereas the remaining lines were resistant to alveolar bone loss. Gender effects on bone volume were tested across the four inbred and 23 CC lines, and found not to be significant. Based on ANOVA analyses, broad-sense heritabilities were statistically significant and equal to 0.4 for CBV and 0.2 for LBV. The moderate heritability values indicate that the variation in host susceptibility to the disease is controlled to an appreciable extent by genetic factors. These results strongly support the possibility of using the Collaborative Cross, as well as developing dedicated F2 (resistant x susceptible inbred strains) resource populations, for future dissection of genetic factors in periodontitis.
    BMC Genetics 08/2013; 14(1):68. · 2.81 Impact Factor
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    ABSTRACT: To investigate the in vivo role of gingipains in Porphyromonas gingivalis' virulence, and suggest a possible host mechanisms through which the bacteria cause alveolar bone loss. Mice were orally infected with P. gingivalis wild type, or the gingipains mutants (RgpA(-) , Kgp(-) , RgpA(-) /Kgp(-) ). Mice were analysed for alveolar bone loss using micro-computed tomography. The molecular effects of the proteases were evaluated using the subcutaneous chamber model. Mice were infected with P. gingivalis wild type or mutants. Exudates were analysed for cytokine and leukocytes levels, in vivo phagocytosis, P. gingivalis survival and serum anti-P. gingivalis IgG titres. Only RgpA-expressing bacteria induced significantly alveolar bone loss, and suppressed phagocytosis resulting in increased survival of P. gingivalis in the chamber exudates. In addition, RgpA-expressing bacteria induced higher levels of leukocytes and cytokines 2 h post-infection, and reduced levels of serum anti-P. gingivalis IgG titres 7 days post-infection. Our findings showed that elimination of RgpA from P. gingivalis diminished inflammation, but augmented phagocytosis and antibody titres, coincidental with reduced alveolar bone loss. These findings support the hypothesis that RgpA is a critical virulence factor in the pathogenesis of experimental periodontitis in mice.
    Journal Of Clinical Periodontology 07/2013; · 3.69 Impact Factor
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    ABSTRACT: Background:Repetitive exposures to periodontal pathogens are regularly employed to induce periodontitis, an inflammatory disease destructing the tooth supporting tissues. Nevertheless, it is unclear what impact such recurring infections have on the immune system, driving to the development of destructive immunity and alveolar bone loss (ABL). Objective: To elucidate systemic and local mechanisms involved in the transition of periopathogen-specific immunity from protective to destructive one. Methods: A single versus three oral gavages with Porphyromonas gingivalis (Pg) 53977 (109 CFU) were administrated into mice. ABL was measured 6 weeks later using µCT. Systemic immune responses were analyzed by cytokine production following splenocytes restimulation and serum IgG levels. Local (gingival) immunity involved cellular analysis of cells infiltrating/departing the gingiva, their phenotype and function using flow cytometry. Results: Both repeated and single exposures to Pg resulted in local inflammation, whereas repeated exposures generated a significant ABL. Higher Pg-specific IgG1 and IgG2a titers and IFN-γ levels were found in mice repeatedly exposed to Pg. T cells from these mice also secreted spontaneously elevated levels of IFN-γ, suggesting a chronic activation of the cells. In the gingiva, a single exposure allowed normal resolution of inflammation, while repeated exposures caused a temporal, but drastic, decrease in the numbers of gingival immune cells. This includes a reduction in the numbers of Langerhans cells, monocytes and IL-17-producing CD4+ T cells, which are essential for controlling infection and regulating immune responses. The gingiva then restored its immune cells content, but this involved an increase in lymphocyte numbers including RANKL-expressing CD4+ T cells, known to mediate ABL. Conclusion: We suggest that several exposures to Pg impair the ability of the gingiva to control infection and local inflammation. This results in a chronic activation of Th1-type T cells followed by increased gingival inflammation and accumulation of immune cells mediating bone-destruction.
    IADR Israeli Division Meeting 2013; 06/2013
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    ABSTRACT: Objective: To evaluate the ability of cysteine proteases from Porphyromonas gingivalis (gingipains) to cleave the innate immune receptors involved in its bacterial recognition and to evaluate the consequences of cleavage for the cellular response to infection with live bacteria. Method: Primary murine peritoneal macrophages or macrophage cell lines were exposed to supernatants of wild type, Rgp- or Kgp-P.gingivalis or to purified gingipains (RgpA, RgpB or Kgp) for 5-60 minutes. Macrophage surface expression of TLR2, TLR4 and CD14 was determined by flow cytometry. TNF-α secretion by CD14 cleaved RAW246.7 macrophages or peritoneal elicited macrophages (1uM Kgp, 30-minutes) or CD14-/- macrophages was measured (ELISA) following stimulation with increasing MOI of P. gingivalis. Result: RgpA and Kgp decreased CD14 detection in a concentration (P=0.0000002) and time (P=0.03) dependent-manner, whereas RgpB did not have a significant effect. The type of gingipain influenced the strength of CD14 cleavage with Kgp>>RgpA>>RgpB. Kgp-mediated CD14 cleavage appeared faster and with lower protease concentration than with RgpA. Gingipains did not significantly affect TLR2 or TLR4 expression on murine-macrophages. Macrophage TNF-α secretion following stimulation with live P.ginginvalis was reduced by pre-treatment with Kgp. Furhermore, TNF-α secretion by CD14-/- macrophages following live P.gingivalis stimulation was lower compared to RAW-macrophages Conclusion: The gingipain hemaglutinin/adhesion site is important in cleaving murine CD14 since only RgpA and Kgp were able to efficiently cleave it.This cleavage resulted in decreased macrophage TNF-α secretion following live P. gingivalis challenge. The fact that gingipains demonstrate selective cleavage of key innate-immune receptors leading to decreased TNF-α levels suggests that they play an important role in modulating the host immune response to P. gingivalis, setting the stage for chronic infection.
    IADR Israeli Division Meeting 2013; 06/2013
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    ABSTRACT: T cells, particularly CD4(+) T cells, play a central role in both progression and control of periodontal disease, whereas the contribution of the various CD4(+) T helper subsets to periodontal destruction remains controversial, the activation, and regulation of these cells is orchestrated by dendritic cells. As sentinels of the oral mucosa, dendritic cells encounter and capture oral microbes, then migrate to the lymph node where they regulate the differentiation of CD4(+) T cells. It is thus clear that dendritic cells are of major importance in the course of periodontitis, as they hold the immunological cues delivered by the pathogen and the surrounding environment, allowing them to induce destructive immunity. In recent years, advanced immunological techniques and new mouse models have facilitated in vivo studies that have provided new insights into the developmental and functional aspects of dendritic cells. This progress has also benefited the characterization of oral dendritic cells, as well as to their function in periodontitis. Here, we provide an overview of the various gingival dendritic cell subsets and their distribution, while focusing on their role in periodontal bone loss.
    Oral Diseases 04/2013; · 2.38 Impact Factor
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    ABSTRACT: We have developed a technique to precisely isolate and process murine gingival tissue for flow cytometry and molecular studies. The gingiva is a unique and important tissue to study immune mechanisms because it is involved in host immune response against oral biofilm that might cause periodontal diseases. Furthermore, the close proximity of the gingiva to alveolar bone tissue enables also studying bone remodeling under inflammatory conditions. Our method yields large amount of immune cells that allows analysis of even rare cell populations such as Langerhans cells and T regulatory cells as we demonstrated previously (1). Employing mice to study local immune responses involved in alveolar bone loss during periodontal diseases is advantageous because of the availability of various immunological and experimental tools. Nevertheless, due to their small size and the relatively inconvenient access to the murine gingiva, many studies avoided examination of this critical tissue. The method described in this work could facilitate gingival analysis, which hopefully will increase our understating on the oral immune system and its role during periodontal diseases.
    Journal of Visualized Experiments 01/2013;
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    ABSTRACT: Objectives: To evaluate the ability of Porphyromonas gingivalis' cysteine proteases (gingipains) to cleave the innate immune receptors involved in bacterial recognition and to evaluate the consequences of cleavage for the cellular response to infection with live bacteria. Methods: Primary murine peritoneal macrophages or macrophage cell lines were exposed to supernatants of wild type, Rgp- or Kgp-P.gingivalis or to purified gingipains (RgpA, RgpB or Kgp) for 5-60 minutes. Macrophage surface expression of TLR2, TLR4 and CD14 was determined by flow cytometry. TNF-α secretion by CD14 cleaved RAW246.7 macrophages or peritoneal elicited macrophages (1uM Kgp, 30-minutes) or CD14-/- macrophages was measured (ELISA) following stimulation with increasing MOI of P. gingivalis. Results: RgpA and Kgp decreased CD14-detection in a concentration (P=0.0000002) and time (P=0.03) dependent-manner, whereas RgpB did not have a significant effect. The type of gingipain influenced the strength of CD14-cleavage with Kgp>>RgpA>>RgpB. Kgp-mediated CD14 cleavage appeared faster and with lower protease concentration than with RgpA. Gingipains did not significantly affect TLR2 or TLR4 expression on murine-macrophages. Macrophage TNF-α secretion following stimulation with live P.ginginvalis (MOI 10,50) was significantly reduced by pre-treatment with Kgp (p value<0.05). Furhermore, TNF-α secretion by CD14-/- macrophages following live P.gingivalis stimulation was significantly lower compared to RAW-macrophages (p value<0.01 for MOI 10,25; p value<0.05 for MOI 50,100). Conclusions: The gingipain hemaglutinin/adhesion site is important in cleaving murine CD14 since only RgpA and Kgp efficiently cleaved it. This cleavage resulted in decreased macrophage TNF-α secretion following live P. gingivalis challenge. The fact that gingipains demonstrate selective cleavage of key innate-immune receptors leading to decreased TNF-α levels suggests that they play an important role in modulating the host immune response to P. gingivalis, setting the stage for chronic infection.
    PER/IADR Congress 2012; 09/2012
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    ABSTRACT: Excessive bone resorption is frequently associated with chronic infections and inflammatory diseases. Whereas T cells were demonstrated to facilitate osteoclastogenesis in such diseases, the role of dendritic cells, the most potent activators of naive T cells, remains unclear. Using a model involving inflammation-driven alveolar bone loss attributable to infection, we showed that in vivo ablation of Langerhans cells (LCs) resulted in enhanced bone loss. An increased infiltration of B and T lymphocytes into the tissue surrounding the bone was observed in LC-ablated mice, including receptor activator of NF-κB ligand (RANKL)-expressing CD4(+) T cells with known capabilities of altering bone homeostasis. In addition, the absence of LCs significantly reduced the numbers of CD4(+)Foxp3(+) T-regulatory cells in the tissue. Further investigation revealed that LCs were not directly involved in presenting antigens to T cells. Nevertheless, despite their low numbers in the tissue, the absence of LCs resulted in an elevated activation of CD4(+) but not CD8(+) T cells. This activation involved elevated production of IFN-γ but not IL-17 or IL-10 cytokines. Our data, thus, reveal a protective immunoregulatory role for LCs in inflammation-induced alveolar bone resorption, by inhibiting IFN-γ secretion and excessive activation of RANKL(+)CD4(+) T cells with a capability of promoting osteoclastogenesis.
    Proceedings of the National Academy of Sciences 04/2012; 109(18):7043-8. · 9.81 Impact Factor
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    ABSTRACT: Periodontitis is a common human chronic inflammatory disease that results in the destruction of the tooth attachment apparatus and tooth loss. Although infections with periopathogenic bacteria such as Porphyromonas gingivalis (P. gingivalis) and Fusobacterium nucleatum (F. nucleatum) are essential for inducing periodontitis, the nature and magnitude of the disease is determined by the host's immune response. Here, we investigate the role played by the NK killer receptor NKp46 (NCR1 in mice), in the pathogenesis of periodontitis. Using an oral infection periodontitis model we demonstrate that following F. nucleatum infection no alveolar bone loss is observed in mice deficient for NCR1 expression, whereas around 20% bone loss is observed in wild type mice and in mice infected with P. gingivalis. By using subcutaneous chambers inoculated with F. nucleatum we demonstrate that immune cells, including NK cells, rapidly accumulate in the chambers and that this leads to a fast and transient, NCR1-dependant TNF-α secretion. We further show that both the mouse NCR1 and the human NKp46 bind directly to F. nucleatum and we demonstrate that this binding is sensitive to heat, to proteinase K and to pronase treatments. Finally, we show in vitro that the interaction of NK cells with F. nucleatum leads to an NCR1-dependent secretion of TNF-α. Thus, the present study provides the first evidence that NCR1 and NKp46 directly recognize a periodontal pathogen and that this interaction influences the outcome of F. nucleatum-mediated periodontitis.
    PLoS Pathogens 03/2012; 8(3):e1002601. · 8.14 Impact Factor
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    ABSTRACT: Background: Implantoplasty is one of the options in treating peri-implantitis. The efficacy of the dental bur used can reduce the time needed for the procedure and, as a consequence, minimize the risk of overheating that can negatively affect the remaining bone surrounding the implant. Purpose: The aim of this study was to evaluate the efficacy of three dental burs in removing implant substance (titanium) and to determine the amount of heat generated by each bur. Materials and Methods: Four burs with different surface properties (diamond, diamond - Premium Line, carbide, and smooth bur - control [Strauss Co., Raanana, Israel]) were attached to a high-speed handpiece and applied to a titanium implant for a total of 60 seconds after cooling by water spray. Variations in temperature were recorded every 5 seconds, and the amount of implant substance removed (reduction in weight of the implant) was evaluated. Results: The diamond Premium Line bur removed 59.24 mg; carbide, 29.39 mg; diamond, 11.35 mg; and smooth bur (control) 0.19 mg, statistically significant. Only minimum thermal changes (∼1.5°C) were recorded for all four burs. Conclusions: There are considerable differences in efficiency of different burs working on titanium. Selecting the proper bur can reduce working time. Under proper cooling conditions, implantoplasty does not generate excess temperature increases that can damage soft tissue or bone surrounding the treated implant.
    Clinical Implant Dentistry and Related Research 07/2011; · 3.82 Impact Factor
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    ABSTRACT: Objectives: To examine whether oral lichen planus (OLP) affects the success rate of dental implants and if the manifestations of OLP are altered by implant-borne prostheses. Materials and Methods: OLP patients, treated in the oral medicine department, with (the study group) and without (control group) dental implants were included. Pocket depth, mobility, bleeding on probing, erythema, pain and radiolucency around the implants, as well as clinical findings and OLP symptoms were recorded. Follow-up ranged from 12-24 months. Ordinal variables and visual analog scale score were compared using the Mann-Whitney test. The significance of the trend within each of the groups was assed using the Friedman test. Categorical variables were compared using Pearson chi-squared test and Fisher's exact test. Results: Fourteen patients in the study group with 1-15 implants per patient and 15 in the control group were included. No implant failures were recorded. Comparison between the clinical manifestations of OLP in both groups did not reveal any significant differences. Conclusions: Success of implant rehabilitation among treated OLP patients does not seem to be different from the success rate in the general population. Nor does implant placement influence the disease manifestations.
    Clinical Implant Dentistry and Related Research 05/2011; · 3.82 Impact Factor
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    ABSTRACT: Although oral dendritic cells (DCs) were shown to induce cell-mediated immunity, the identity and function of the various oral DC subsets involved in this process is unclear. In this study, we examined the mechanisms used by DCs of the buccal mucosa and of the lining mucosa to elicit immunity. After plasmid DNA immunization, buccally immunized mice generated robust local and systemic CD8(+) T cell responses, whereas lower responses were seen by lining immunization. A delayed Ag presentation was monitored in vivo in both groups; yet, a more efficient presentation was mediated by buccal-derived DCs. Restricting transgene expression to CD11c(+) cells resulted in diminished CD8(+) T cell responses in both oral tissues, suggesting that immune induction is mediated mainly by cross-presentation. We then identified, in addition to the previously characterized Langerhans cells (LCs) and interstitial dendritic cells (iDCs), a third DC subset expressing the CD103(+) molecule, which represents an uncharacterized subset of oral iDCs expressing the langerin receptor (Ln(+)iDCs). Using Langerin-DTR mice, we demonstrated that whereas LCs and Ln(+)iDCs were dispensable for T cell induction in lining-immunized mice, LCs were essential for optimal CD8(+) T cell priming in the buccal mucosa. Buccal LCs, however, failed to directly present Ag to CD8(+) T cells, an activity that was mediated by buccal iDCs and Ln(+)iDCs. Taken together, our findings suggest that the mechanisms engaged by oral DCs to prime T cells vary between oral mucosal tissues, thus emphasizing the complexity of the oral immune network. Furthermore, we found a novel regulatory role for buccal LCs in potentiating CD8(+) T cell responses.
    The Journal of Immunology 01/2011; 186(2):891-900. · 5.52 Impact Factor
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    ABSTRACT: To assess the potential of using vaccination with Porphyromonas gingivalis or Fusobacterium nucleatum, in modulating local subcutaneous inflammatory response and alveolar bone loss following coinfection with both bacteria. Mice were immunized against either P. gingivalis or F. nucleatum. The cytokine response to mixed infection with P. gingivalis and F. nucleatum was evaluated using the subcutaneous chamber model. The alveolar bone loss induced by oral mixed infection was evaluated by micro-CT using the experimental periodontitis model. Serum levels of specific antibodies were determined by ELISA. Vaccination with either bacterium produced a specific humoral response before infection. Animals immunized against either bacteria following a mixed infection with P. gingivalis and F. nucleatum, showed decreased TNFalpha (but not IL-1beta) levels as compared with non-immunized animals. However, the vaccination did not change the level of mixed infection-induced alveolar bone loss when compared with non-immunized animals. Six weeks following the oral mixed infection, specific antibody titres remained high. Furthermore, specific antibodies against the non-immunized bacterium were present at high levels. While vaccination produced specific antibodies and suppressed the inflammatory response, it failed to prevent or reduce the progression of experimental periodontitis induced by mixed infection with P. gingivalis and F. nucleatum.
    Journal Of Clinical Periodontology 09/2010; 37(9):812-7. · 3.69 Impact Factor
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    ABSTRACT: Background: Dendritic cells (DCs) are the most potent antigen-presenting cells for initiating T-cell responses against systemic and oral pathogens. Nevertheless, although DC function has been extensively studied, oral DCs have been generally overlooked and most of our knowledge is based on research of other tissues. Thus, investigating the role of oral DCs in immune induction is important for better understating and modulation of the oral immune system. Objectives: To characterize the mechanisms utilized by DCs in the buccal and lining mucosal tissues for the generation of cellular immunity. Methods: We utilized plasmid DNA to initiate antigen expression and to induce T-cell activation by the noted periodontal tissues. The kinetics of antigen presentation and CD8+ T cell response were evaluated by adoptive transfer and tetramer analysis. Identification of migratory oral DC subsets was accomplished by magnetic separation and multi-channel flow cytometry. Langerin-DTR mice were employed for in vivo ablation of langerin-expressing DCs. Results: Targeting the buccal and lining mucosa for immune induction resulted in unique kinetics of antigen expression and T-cell formation for each tissue. Following immunization similar populations of DCs migrated to the lymph nodes (LNs) from the buccal and lining mucosa including: Langerhans cells (LCs), interstitial DCs (iDCs) and langerin+ iDCs (Ln+iDCs). While depletion of LCs did not affect T-cell induction in both tissues, Ln+iDCs of the buccal mucosa, but not lining mucosa, were crucial for effective T cell immunity (P<0.005). Furthermore, upon arrival to the LNs, buccal-derived DCs initiate earlier and stronger antigen presenting activity as compared to lining-derived DCs. Conclusion: We demonstrate that the mechanisms engaged by oral DCs to prime T cells vary between periodontal tissues, thus emphasizing the complexity of the oral immune network. We also suggest that periodontal tissues can be promising targets for induction of systemic and local cellular immunity.
    IADR General Session 2010; 07/2010
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    ABSTRACT: Introduction: P.gingivalis and F.nucleatum are considered as important pathogens in the pathogenesis of periodontal disease. A destructive synergistic effect between these two bacteria was observed in the experiemtal periodontitis model in mice, but the effect of co-aggregation between the bacteria on experimental periodontitis was never characterized. Objectives: to investigate the role of coaggregation between P. gingivalis and F. nucleatum on the virulence of the mixed infection, both at the clinical and molecular levels. Methods: The experimental periodontitis model using mixed infection with P. gingivalis and F. nucleatum in mice was utilized to investigate alveolar bone loss. The subcutaneous chamber model was used to investigate the inflammatory response to the mixed infection and also to investigate bacteria clearance by immune cells. The inhibition of co-aggregation was induced using lactose. Results: Mixed infection with P. gingivalis and F. nucleatum induced significant alveolar bone loss compared with mono-infection with either bacterium or in the sham-infected animals. The inhibition of coaggregation by lactose resulted in augmentation of alveolar bone loss compared with mixed infection without lactose. Inhibition of coaggregation resulted in reduced IL-1β, but not TNFα, compared with mixed infection without lactose. Phagocytosis of P. gingivalis in mono-infection was greater than the phagocytosis in mixed infection with F. nucleatum. The inhibition of coaggregation in mixed infection resulted in increased P. gingivalis phagocytosis and reduced F. nucleatum phagocytosis. Conclusions: Coaggregation between P. gingivalis and F. nucleatum is a major virulence factor in mixed infection experimental periodontitis. The elimination of coaggregation with lactose results in augmentation of alveolar bone loss Although the P. gingivalis clearance was increased .
    IADR General Session 2010; 07/2010
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    ABSTRACT: Background: Gingipains, a group of proteases produced by P. gingivalis, are one of the bacteria's major virulence factors. Objectives: To evaluate the role of gingipains in the in-vivo survival of P. gingivalis and to investigate their effects on the mouse immune response. Methods: Subcutaneous chambers in mice were infected with wild-type P. gingivalis or RgpA-, or Kgp- mutants. Exudates were analyzed by flow cytometry for in-vivo phagocytosis, P. gingivalis survival was evaluated by culture and cytokine levels were determined by ELISA. Serum anti-P. gingivalis IgG titers were measured using ELISA. Results: Two hours post-infection the percentage of leukocytes that engulfed the RgpA- bacteria was significantly higher than the RgpA+ (wild-type and Kgp-) bacteria. In-addition, the average number of engulfed bacteria in each leukocyte was significantly higher for the RgpA- bacteria compared to the RgpA+ bacteria. At 24 and 48 hours no significant differences were observed between the groups. These results correlated with the microbiological cultures, since at 2 hours post-infection significantly less RgpA-P. gingivalis survived compared to RgpA+P. gingivalis. We further found that RgpA-P. gingivalis induces significantly higher serum anti-P. gingivalis IgG titers compared to RgpA+P. gingivalis, which may also reflect more phagocytosis and subsequent antigen presentation. Finally, wild-type P. gingivalis induced higher levels of cytokines in the chambers compared to RgpA-P. gingivalis. Conclusions: RgpA's virulence is highlighted by its ability to suppress in-vivo phagocytosis and serum anti-P. gingivalis IgG titers while simultaneously increasing proinflammatory cytokines. The inflammation will not lead to bacterial clearance but may significantly contribute to the alveolar bone loss seen in the experimental periodontitis model.
    IADR General Session 2010; 07/2010
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    ABSTRACT: To evaluate the effect of oral infection with three Porphyromonas gingivalis strains on alveolar bone loss (ABL) and its correlation with the mouse immune response. Mice were orally infected with P. gingivalis strains 381, 33277 and 53977. After 42 days, maxillae were analysed for ABL using micro-computed tomography and the serum for anti-P.gingivalis IgG1 and IgG2a levels. The cytokine response to P. gingivalis was tested using the subcutaneous chamber model. The P. gingivalis 53977-infected group showed the highest ABL, which was significantly different from all other groups (p<0.001). In addition, the humoral response to P. gingivalis 53977 was significantly lower than the response to P. gingivalis 381 and 33277 (p< or =0.01). The IgG2a/IgG1 ratio was higher in the P. gingivalis 33277-infected group (1.6) compared with the P. gingivalis 381-infected group (0.51). Four days post-infection, interleukin (IL)-1beta levels remained significantly higher in the P. gingivalis 53977-infected group only (1198.2+/-260.0, p<0.05), while IL-4 levels remained significantly higher in the P. gingivalis 381-infected group (265.8+/-131.6, p<0.05). The high levels of ABL induced by P. gingivalis 53977 were inversely correlated with the humoral response to this bacterium. In addition, ABL was correlated with an elevated pro-inflammatory response.
    Journal Of Clinical Periodontology 09/2009; 36(11):915-21. · 3.69 Impact Factor
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    ABSTRACT: The chemistry of titanium is a key factor in determining implant-tissue interactions. Reports that a vanadium-based titanium alloy (Ti-6Al-4V) exhibits some cytotoxicity led to a search for an alternative. The aim of the present study was to investigate the behavior of human osteoblast-like cells (Saos-2) cultured on Ti-6Al-4V or Ti-6Al-7Nb disks with a rough or a machined surface. In all four groups, the cells proliferated rapidly between days 1 and 3, and then plateaued. On day 1 of culture, the highest proliferation rate was of cells cultured on disks containing Nb with a machined surface. On day 7, there was no significant difference in cell density on all the tested surfaces. Alkaline phosphatase (ALP) activity was lower on the machined surfaces, regardless of the material used, suggesting that cells on rough surfaces exhibit a more mature phenotype. On day 3, cells cultured on rough disks made of Ti-6Al-7Nb showed the highest ALP activity; the lowest activity was observed on the machined Ti-6Al-4V surface. The highest level of osteocalcin (day 7) was found in the cells cultured on rough Ti-6Al-7Nb disks. Also, higher levels of transforming growth factor (TGFbeta) were noted for cells cultured on the rough Ti-6Al-7Nb disks, suggesting that the Nb-containing alloy supports more rapid maturation of the osteoblast. The results of the present study suggest that according to our cell culture preclinical model, Ti-6Al-7Nb may replace the Ti-6Al-4V alloy as an implant material.
    Clinical Oral Implants Research 07/2009; 20(6):578-82. · 3.43 Impact Factor
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    ABSTRACT: To compare the effect of oral infection with Porphyromonas gingivalis or Fusobacterium nucleatum versus infection with both bacteria on mouse periodontal tissues, and to characterize the inflammatory response. Mice were orally infected with P. gingivalis, F. nucleatum or both. At 42 days post-infection, alveolar bone loss was quantified using micro-computerized tomography. Tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-1beta levels induced by the infection were quantified using the subcutaneous chamber model. Mice orally infected with F. nucleatum/P. gingivalis exhibited significantly more bone loss compared with that of mono-infected and sham-infected mice. F. nucleatum/P. gingivalis infection also increased the levels of TNF-alpha and IL1beta compared with the levels found in the mono-infected groups. Polymicrobial infection with P. gingivalis/F. nucleatum aggravates alveolar bone loss and induces a stronger inflammatory response compared with that observed upon infection with either bacterium alone. The results suggest that oral infection of mice with a mixture of P. gingivalis and F. nucleatum may be superior to mono-infection models of experimental periodontitis.
    Journal Of Clinical Periodontology 06/2009; 36(5):406-10. · 3.69 Impact Factor

Publication Stats

241 Citations
74.62 Total Impact Points

Institutions

  • 2007–2014
    • Hebrew University of Jerusalem
      • • Department of Periodontology
      • • Institute of Dental Sciences
      • • Department of Oral Rehabilitation
      Yerushalayim, Jerusalem District, Israel
  • 2013
    • Hadassah Medical Center
      Yerushalayim, Jerusalem District, Israel
    • Tel Aviv University
      • Department of Clinical Microbiology and Immunology
      Tell Afif, Tel Aviv, Israel