Effects of resveratrol on expression of vascular endothelial growth factor in human gingival fibroblasts stimulated by periodontal pathogens.

OBJECTIVE: To investigate the effects of resveratrol, a naturally occurring polyphenol, on the expression of vascular endothelial growth factor (VEGF) in human gingival fibroblast culture in response to vesicles and outer membrane proteins from periodontopathic bacteria. MATERIAL AND METHODS: Human gingival fibroblasts were stimulated with vesicles and outer membrane proteins from Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis. In human gingival fibroblast cultures treated with or without resveratrol, VEGF production was evaluated by means of enzyme-linked immunosorbent assay and VEGF mRNA expression by means of reverse transcription polymerase chain reaction analysis. Vascular permeability enhancement was measured by the leakage of intravenously injected dye at the injection site of supernatant from cultures of human gingival fibroblasts stimulated by vesicles and outer membrane proteins. RESULTS: Resveratrol significantly inhibited the increased production of VEGF by human gingival fibroblasts in response to vesicles and outer membrane proteins from periodontopathic bacteria, as shown by the detection of these proteins and their mRNA in vitro. Moreover, resveratrol treatment significantly decreased vascular permeability enhancement induced by supernatant from human gingival fibroblast cultures stimulated by vesicles and outer membrane proteins. CONCLUSIONS: Overall, these findings suggest that resveratrol inhibits production of VEGF by stimulated human gingival fibroblasts and can inhibit vascular permeability, suggesting a therapeutic role for it in pathogenic bacteria-induced periodontal inflammation.

Inflammatory responses of gingival epithelial cells stimulated with Porphyromonas gingivalis vesicles are inhibited by hop-associated polyphenols.

BACKGROUND: Periodontitis is induced by an imbalance between bacterial virulence and host defense ability. Porphyromonas gingivalis, a predominant periodontal pathogen, triggers a series of host inflammatory responses that aggravate the destruction of periodontium. Thus, anti-inflammatory reagents are considered desirable for effective periodontal therapy. In the present study, we examined the inhibitory effects of hop bract polyphenol (HBP) on cellular inflammatory responses induced by P. gingivalis membrane vesicles. METHODS: Immortalized human gingival epithelial cells were stimulated with P. gingivalis membrane vesicles, and the effects of HBP on mRNA expression of cyclooxygenase (COX)-2, interleukin (IL)-6 and -8, and matrix metalloproteinase (MMP)-1 and -3 were examined using real-time reverse transcription-polymerase chain reaction. RESULTS: HBP inhibited the mRNA expression of COX-2, IL-6 and -8, and MMP-1 and -3 in a dose-dependent manner, whereas epigallocatechin gallate (a control polyphenol) inhibited COX-2 mRNA expression only. Following further fractionation of HBP to identify the effective components, 2-[(2-methylpropanoyl)-phloroglucinol]1-O-beta-D-glucopyranoside (MPPG) was identified as a significant anti-inflammatory element that completely inhibited the inflammatory mRNA induction. Kaempferol 3-O-beta-glucopyranoside (astragalin) also was found to have anti-inflammatory effects. CONCLUSIONS: HBP is suggested to be a potent inhibitor of cellular inflammatory responses induced by P. gingivalis vesicles. Further, MPPG and astragalin, identified here as effective components of HBP, also may be useful for the prevention and/or attenuation of periodontitis.

Epithelial cell rests of Malassez and OX6-immunopositive cells in the periodontal ligament of rat molars: a light and transmission electron microscope study.

It has been shown that human and cat epithelial cell rests of Malassez (ERM) consist of heterogeneous cell populations. Immunohistochemical and immunoelectron microscopic analyses have verified the presence of neuroendocrine and Merkel-like cells in both of these epithelia. During experimental orthodontic tooth movement, immunocompetent cells have also been found in the vicinity of ERM in rat periodontal ligament (PDL), but have not been characterized in normal rat PDL. The aim of this study was to investigate the presence and distribution of MHC class II antigen presenting cells by using OX6 antibody in ERM of rat molars by light and transmission electron microscopy. Immunohistochemical and immunoelectron microscopic observations of rat maxillary molars confirmed the presence of OX6-positive cells in contact with ERM. Some immunopositive cytoplasmic processes containing vesicles interdigitated with cells of the Malassez epithelial clusters. Based on these findings it can be concluded that immunocompetent cells are localized close to Malassez epithelial clusters in normal rat PDL. Furthermore, the ultrastructural evidences indicate a possible interaction between the epithelial and immunocompent cells and suggest morphological and functional properties for ERM.

Immunological and ultrastructural characterization of plasma cells of human periapical chronic inflammatory lesions (granulomas).

Despite many studies on the topic, plasma cells found in human periapical chronic inflammatory lesions (granulomas) continue to present unresolved issues. In this study, we tried to assess quantitatively and qualitatively the nature of plasma cells of 4 human periapical granulomas. Samples were analyzed for relative amounts of IgG-, IgM-, IgA-, and IgE-positive plasma cells by immunohistochemistry, and for morphological changes by transmission electron microscopy (TEM). By immunohistochemistry, many plasma cells stained positively with anti-IgG and anti-IgM antibodies; fewer cells reacted with anti-IgE and anti-IgA. Russell Bodies, controversial aspects of plasma cell maturation, showed positive reactivity of the superficial layer only to antibodies against IgG and IgM. By TEM analysis, phenotypes of normal and dysfunctional plasma cells (Mott cells) were evident. Russell Bodies appeared as intra- or extracellular round vesicles, with an homogeneous internal core, and an external membrane, resembling rough endoplasmatic reticulum (RER). We can conclude that mucosal immune response is not the predominant type in the periapical lesions examined. Positive immunoreaction for IgG and IgM of Russell Bodies may be due to the residual RER membrane, whereas components of yet unidentified nature may occupy the internal core.

T cells distinguish MHC-peptide complexes formed in separate vesicles and edited by H2-DM.

The peptide spanning residues 48-61 of hen egg white lysozyme (HEL) presented by I-A(k) gives rise to two T cell populations, referred to as type A and B, that distinguish the complex generated intracellularly upon processing of HEL from that formed with exogenous peptide. Here, we ascribe this difference to recognition of distinct conformers of the complex and show that formation of the two complexes results from antigen processing in different intracellular compartments and is dependent upon H2-DM. While the type A complex preferentially formed in a lysosome-like late vesicle, the type B complex failed to form in this compartment; this distinction was abolished in antigen-presenting cells lacking DM. Experiments in vitro indicated that H2-DM acts directly on the complex to eliminate the type B conformation. We conclude that different antigen-processing pathways generate distinct MHC-peptide conformers, priming T cells with distinct specificity that may play unique roles in immunity.