Search

Periodontitis, a ubiquitous chronic inflammatory disease, is associated with reduced antioxidant defences and neutrophil hyperactivity in terms of reactive oxygen species (ROS) generation. Its phenotype is thus characterized by oxidative stress. We have determined the effect of antioxidant micronutrients ascorbate and α-tocopherol on neutrophil ROS generation. Peripheral neutrophils from periodontally-healthy individuals (n = 20) were challenged with phorbol myristate acetate, IgG-opsonised Staphylococcus aureus, Fusobacterium nucleatum or PBS in the presence and absence of micronutrients (50 µM). Total and extracellular ROS were measured by luminol and isoluminol chemiluminescence respectively. Total and extracellular unstimulated, baseline ROS generation was unaffected by α-tocopherol, but inhibited by ascorbate and a combination of both micronutrients. Fcγ-receptor (Fcγ-R)-stimulated total or extracellular ROS generation was not affected by the presence of individual micronutrients. However, the combination significantly reduced extracellular FcγR-stimulated ROS release. Neither micronutrient inhibited TLR-stimulated total ROS, but the combination caused inhibition. Ascorbate and the micronutrient combination, but not α-tocopherol, inhibited extracellular ROS release by TLR-stimulated cells. Such micronutrient effects in vivo could be beneficial in reducing collateral tissue damage in chronic inflammatory diseases, such as periodontitis, while retaining immune-mediated neutrophil function. [ABSTRACT FROM PUBLISHER]

Chronic periodontal diseases are characterised by a dysregulated and exaggerated inflammatory/immune response to plaque bacteria. We have demonstrated previously that oral keratinocytes up-regulate key molecular markers of inflammation, including NF-κB and cytokine signalling, when exposed to the periodontal bacteria Porphyromonas gingivalis and Fusobacterium nucleatum in vitro. The purpose of the current study was to investigate whether α-lipoic acid was able to abrogate bacterially-induced pro-inflammatory changes in the H400 oral epithelial cell line. Initial studies indicated that α-lipoic acid supplementation (1–4 mM) significantly reduced cell attachment; lower concentrations (<0.5 mM) enabled >85% cell adhesion at 24 h. While a pro-inflammatory response, demonstrable by NF-κB translocation, gene expression and protein production was evident in H400 cells following exposure to P. gingivalis and F. nucleatum, pre-incubation of cells with 0.5 mM α-lipoic acid modulated this response. α-Lipoic acid pre-treatment significantly decreased levels of bacterially-induced NF-κB activation and IL-8 protein production, and differentially modulated transcript levels for IL-8, IL-1β, TNF-α and GM-CSF, TLR2, 4, 9, S100A8, S100A9, lysyl oxidase, NF-κB1, HMOX, and SOD2. Overall, the data indicate that α-lipoic acid exerts an anti-inflammatory effect on oral epithelial cells exposed to periodontal bacteria and thus may provide a novel adjunctive treatment for periodontal diseases. [ABSTRACT FROM PUBLISHER]

El artículo trata el rol de las especies reactivas de oxígeno y los antioxidantes en el deterioro del tejido periodontal. Informa que el estrés oxidativo es un factor central en el deterioro de los tejidos periodontales debido a la interacción entre el hospedador y los microorganismos. Nota que la reducción de la función antioxidante es otra característica del tejido periodontal de las personas con periodontitis.

Drug therapy and hereditary factors are two of the main causes of gingival overgrowth (GO). Both of these forms of GO are associated with increased extracellular matrix production by fibroblasts. Transforming growth factor beta (TGF-β) is an important mediator of wound healing and tissue regeneration, which stimulates fibroblasts to produce extracellular matrix materials. The aim of this immunohistochemical study was to determine whether there is any altered expression of TGF-β isoforms or its receptors in tissue from patients with drug-induced GO (DIGO; n=10) and hereditary gingival fibromatosis (n=10) when compared to non-overgrowth tissue (n-10). Compared to control tissues, significantly more fibroblasts expressed TGF-β in both DIGO and hereditary gingival fibromatosis tissues (P<0.03). Cells expressing TGF-β2 were present at control levels in DIGO but were significantly reduced in hereditary gingival fibromatosis (P<0.02). By contrast, the number of TGF-β3-positive cells was the same in overgrowth tissues and controls. However, because of differences in total fibroblast densities between groups, there was a proportional increase in TGF-β3 as well as TGF-β1 expressing cells within both overgrowth populations (P<0.0001). Furthermore, representation of the TGF-β2-positive phenotype was reduced in hereditary gingival fibromatosis (P<0.01) but increased in DIGO (P<0.005) compared to controls. Absorbance measurements of the positive cell populations showed that the level of expression was significantly higher for TGF-β1 in hereditary gingival fibromatosis (P<0.002) and significantly lower for TGF-β3 in DIGO (P<0.03). No significant differences in the numbers of TGF-βRl- or RU-positive cells were detected between overgrowth tissues and controls. However, there were increases in the proportion of receptor-positive cells in the total cell population analyzed in overgrowth tissues (P<0.0001). These results indicate qualitative and quantitative differences in TGF-β isoform and receptor expression by fibroblasts in gingival overgrowth that may contribute to disease pathogenesis. [ABSTRACT FROM AUTHOR]

This study examined the metastatic capacity of clonal populations of 4NQO-induced rat malignant oral keratinocytes following orthotopic transplantation to athymic mice. Polygonal and spindle cells formed well-differentiated squamous cell carcinomas (keratin positive and vimentin negative) and undifferentiated spindle cell tumors (keratin negative and vimentin positive), respectively, in almost 100% of animals at the site of inoculation (floor of mouth). Transplantation of 5×106 cells of either cell type at high cell density resulted, in approximately 50% of animals forming pulmonary metastases. By contrast, inoculation of 2×106 differentiated polygonal cells resulted in the formation of significantly fewer pulmonary metastases than the undifferentiated spindle cells. A single well-differentiated clone of polygonal cells and 3 to 4 of the undifferentiated spindle cell lines produced comparable levels of TGF-β1. One undifferentiated spindle cell line expressed significantly more TGF-β1 and, following transplantation orthotopically, fewer animals formed pulmonary metastases despite the formation of primary tumours in almost all grafted animals, suggesting that TGF-β1 can act as a tumour suppressor in this cell type. All cell lines produced comparable amount of TGF-β2. The clones of polygonal cells were markedly inhibited and the spindle cells were only partially inhibited by exogenous TGF-β1. Both cell types expressed high-affinity TGF-β cell surface receptors; the ratio of type I to type II TGF-β receptors were 1.0:<3.0 in the spindle cells and 1.0:17.9 in the polygonal clone. The results suggest that differentiated rat malignant oral keratinocytes are less aggressive and have a decreased potential to metastasise than their undifferentiated spindle cell counter parts. This may be attributable, in part, to a change in TGF-β receptor profile leading to the partial loss of response to exogenous TGF-β1. [ABSTRACT FROM AUTHOR]

Immunoperoxidase staining for a variety of antigens was performed on 15 cases of granular cell myoblastoma occurring within the oral tissues. All tumours gave mtense intracytoplasmic granular staining for a CEA-related antigen with one rabbit antiserum to CEA (Dakopatts) whereas all were negative with a sheep antiserum to CEA (Seward). None of the, turnouts were positive for lysozyme, α[sub1] antitrypsin or cathepsin B whereas 12 lesions gave a granular reaction for cathepsin D. All granular cells showed a weak reaction for actin in contrast to the strong cytoplasmic staining found in smooth and striated muscle and muscle derived tumours. [ABSTRACT FROM AUTHOR]

Porphyromonas gingivalis, a gram-negative anaerobe which is implicated in the etiology of active periodontitis, secretes degradative enzymes (gingipains) and sheds proinflammatory mediators (e.g., lipopolysaccharides [LPS]). LPS triggers the secretion of interleukin-8 (IL-8) from immune (72-amino-acid [aa] variant [IL-8(72aa)]) and nonimmune (IL-8(77aa)) cells. IL-8(77aa) has low chemotactic and respiratory burst-inducing activity but is susceptible to cleavage by gingipains. This study shows that both R- and K-gingipain treatments of IL-8(77aa) significantly enhance burst activation by fMLP and chemotactic activity (P < 0.05) but decrease burst activation and chemotactic activity of IL-8(72aa) toward neutrophil-like HL60 cells and primary neutrophils (P < 0.05). Using tandem mass spectrometry, we have demonstrated that R-gingipain cleaves 5- and 11-aa peptides from the N-terminal portion of IL-8(77aa) and the resultant peptides are biologically active, while K-gingipain removes an 8-aa N-terminal peptide yielding a 69-aa isoform of IL-8 that shows enhanced biological activity. During periodontitis, secreted gingipains may differentially affect neutrophil chemotaxis and activation in response to IL-8 according to the cellular source of the chemokine.

We examined the effect of stable transfection of dominant negative TbetaR-II (dn TbetaR-II) cDNA in a human oral carcinoma cell line that contained normal Ras and was growth inhibited by TGF-beta1. Two clonal cell lines containing dn TbetaR-II were isolated and compared to the vector-only control and parent cell line. The treatment of cells with exogenous TGF-beta1 resulted in a decrease in ligand-induced growth inhibition and loss of c-myc downregulation in test cells compared to controls; transcriptional activation of certain genes including fra-1 and collagenase was retained. Cells containing dn TbetaR-II grew faster in monolayer culture, expressed less keratin 10 and exhibited increased motility and invasion in vitro compared to control cell lines. Endogenous TGF-beta1 production and the regulation of MMP-2 and MMP-9 by TGF-beta1 remained unchanged. After orthotopic transplantation to the floor of the mouth in athymic mice, cells containing dn TbetaR-II formed comparable numbers of primary tumours at the site of inoculation as controls but the tumours were less differentiated as demonstrated by the absence of keratin 10 immunostaining. Further, metastatic dissemination to the lungs and lymphatics was more evident in grafts of cells containing dn TbetaR-II than controls. Taken together, the results demonstrate that attenuation of TGF-beta signalling through transfection of dn TbetaR-II cDNA leads to an enhanced growth rate, a loss of tumour cell differentiation and an increase in migration and invasion, characteristics that corresponded to the development of the metastatic phenotype., (Copyright 2004 Wiley-Liss, Inc.)

The aim of this study was to analyse the tissue surrounding prematurely extruded ventilation tubes (grommets). Thirty-one ventilation tubes, including 21 Shah and six Shepherd tubes, that had been extruded naturally into the ear canal were examined. After formalin fixation, material adhering to the tubes was retrieved and processed to paraffin wax. Five tubes were processed for scanning electron microscope (SEM) analysis. Sections were stained using histochemical methods for collagen, keratin and keratohyaline. In addition, the presence of collagen (type I and III), keratin, vimentin, fibronectin, tenascin, factor VIII-related antigen, CD31 and CD45 was tested for by immunohistochemistry. Results showed that all specimens consisted of an acellular fibrous material, oriented in concentric rings parallel to the tube surface that was often associated with small collections of CD45+ inflammatory cells. Two specimens contained collagen that was detectable by histochemical and immunohistological methods. Twelve specimens contained identifiable desquamated epithelial cells containing keratin and keratohyaline. Only one specimen stained positively for connective tissue markers (vimentin, fibrous fibronectin, tenascin) or showed the presence of vascular epithelium. SEM revealed adherent clusters or sheets of plate-like structures, consistent with the presence of epithelial squames, on three of the five ventilation tubes examined. It is concluded that tissue retained on extruded grommets consists of orthokeratinitizing epithelium infiltrated by inflammatory cells, a finding that is consistent with the theory that tube extrusion occurs as a result of squamous epithelial proliferation, medial migration, differentiation and desquamation.