Diferencia en la expresión del ligando de receptor activador para el factor nuclear K B, en tejido tumoral frente a la infección por diferentes patógenos periodontales / Difference in receptor activator of nuclear factor K B expression in tumoral tissue by different periodontal pathogens

La enfermedad periodontal es una de las principales causas de pérdida dentaria. Clínicamente, esta patología, mediada por la desregulación del sistema inmune producto de una disbiosis ocurrida en el surco gingival, inicia con la inflamación de la encía y evoluciona con el daño irreversible de los tejidos que rodean el diente. El hueso alveolar es uno de los tejidos afectados esta patología, esto debido a la activación de osteoclastos por la sobreexpresión de la proteína RANKL en el huésped. El propósito de este trabajo es determinar el nivel de sobreexpresión de RANKL, en un modelo de células tumorales U2OS, frente a la infección con Porphyromonas gingivalis y Prevotella intermedia. Para identificar el nivel de RANKL, se definieron cuatro grupos: Un grupo control, no tratado; Grupo PG, tratado con P. gingivalis; Grupo PI, tratado con P. Intermedia; y un grupo PG+PI, tratado con ambas bacterias. El nivel relativo de la proteína RANKL fue determinado en el sobrenadante y en los extractos celulares de manera independiente, mediante la técnica Western blot. En sobrenadantes, el grupo PG mostró mayores niveles de RANKL comparados con PI (p < 0,05). En extractos celulares los niveles fueron mayores en el grupo PG+PI (p < 0,05). El grupo PI mostró los niveles más bajos de RANKL. La infección polimicrobiana resulta en una mayor expresión de RANKL en células tumorales U2OS, mientras que frente a la infección P. gingivalis, se observó mayor cantidad de RANKL soluble.

SUMMARY: Periodontal disease is one of the main causes of tooth loss. Clinically, this pathology, mediated by the deregulation of the immune system due to a dysbiosis occurred in the gingival sulcus, begins with the inflammation of the gum and evolves with the irreversible damage of the tissues that surround the tooth. Alveolar bone is one of the most affected tissues by this disease, due to the activation of osteoclasts by the upregulation of RANKL in the host. The aim of this study is to determine the increase of RANKL, in a U2OS tumor cells model, inoculated with Porphyromonas gingivalis and Prevotella intermedia. To identify the level of RANKL, four groups were defined: A control group, not treated; PG group, treated with P.gingivalis; PI group, treated with P. intermedia; and a PG+PI group, treated with both bacteria. The relative level of RANKL was determined in the supernatant and cell extracts independently, using the Western blot technique. In supernatants, the PG group showed higher RANKL levels compared to PI (p < 0.05). In cell extracts the levels were higher in the PG+PI group (p < 0.05.). The PI group showed the lowest levels of RANKL.Polymicrobial infection results in a greater expression of of soluble RANKL was observed.

Root canal contamination or exposure to lipopolysaccharide differentially modulate prostaglandin E 2 and leukotriene B 4 signaling in apical periodontitis

Abstract Purpose To evaluate the kinetics of apical periodontitis development in vivo , induced either by contamination of the root canals by microorganisms from the oral cavity or by inoculation of bacterial lipopolysaccharide (LPS) and the regulation of major enzymes and receptors involved in the arachidonic acid metabolism. Methodology Apical periodontitis was induced in C57BL6 mice (n=96), by root canal exposure to oral cavity (n=48 teeth) or inoculation of LPS (10 µL of a suspension of 0.1 µg/µL) from E. coli into the root canals (n= 48 teeth). Healthy teeth were used as control (n=48 teeth). After 7, 14, 21 and 28 days the animals were euthanized and tissues removed for histopathological and qRT-PCR analyses. Histological analysis data were analyzed using two-way ANOVA followed by Sidak's test, and qRT-PCR data using two-way ANOVA followed by Tukey's test (α=0.05). Results Contamination by microorganisms led to the development of apical periodontitis, characterized by the recruitment of inflammatory cells and bone tissue resorption, whereas inoculation of LPS induced inflammatory cells recruitment without bone resorption. Both stimuli induced mRNA expression for cyclooxygenase-2 and 5-lipoxygenase enzymes. Expression of prostaglandin E 2 and leukotriene B 4 cell surface receptors were more stimulated by LPS. Regarding nuclear peroxisome proliferator-activated receptors (PPAR), oral contamination induced the synthesis of mRNA for PPARδ, differently from inoculation of LPS, that induced PPARα and PPARγ expression. Conclusions Contamination of the root canals by microorganisms from oral cavity induced the development of apical periodontitis differently than by inoculation with LPS, characterized by less bone loss than the first model. Regardless of the model used, it was found a local increase in the synthesis of mRNA for the enzymes 5-lipoxygenase and cyclooxygenase-2 of the arachidonic acid metabolism, as well as in the surface and nuclear receptors for the lipid mediators prostaglandin E2 and leukotriene B4.

Porphyromonas gingivalis decreases osteoblast proliferation through IL-6-RANKL/OPG and MMP-9/TIMPs pathways.

Background: Porphyromonas gingivalis, an important periodontal pathogen, is closely associated with inflammatory alveolar bone resorption. This bacterium exerts its pathogenic effect indirectly through multiple virulence factors, such as lipopolysaccharides, fimbriae, and proteases. Another possible pathogenic path may be through a direct interaction with the host's soft and hard tissues (e.g., alveolar bone), which could lead to periodontitis. Aims and Objectives: The aim of the present study was to investigate the direct effect of live and heat-inactivated P gingivalis on bone resorption, using an in vitro osteoblast culture model. Results: Optical microscopy and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide MTT assay revealed that live P gingivalis induced osteoblast detachment and reduced their proliferation. This effect was specific to live bacteria and was dependent on their concentration. Live P gingivalis increased IL-6 mRNA expression and protein production and downregulated RANKL and OPG mRNA expression. The effect of live P gingivalis on bone resorption was strengthened by an increase in MMP-9 expression and its activity. This increase was accompanied by an increase in TIMP-1 and TIMP-2 mRNA expression and protein production by osteoblasts infected with live P gingivalis. Conclusion: Overall, the results suggest that direct contact of P gingivalis with osteoblasts induces bone resorption through an inflammatory pathway that involves IL-6, RANKL/OPG, and MMP-9/TIMPs.