Search

Aim Test whether human periodontal ligament fibroblasts ( PDLFs) retain homeostatic responses to a physiological compressive force during chronic periodontitis. Material and Methods Six cell lines were established from periodontally healthy individuals (H- PDLFs) and another six were cultured from patients diagnosed with chronic periodontitis (D- PDLFs). Compressive force at 150 psi was applied to H-and D- PDLFs for 3 h on 2 consecutive days. After compression, comparisons between H-and D- PDLFs were performed by gene expression analysis of IL-6, proteases and 84 inflammation-related targets using real-time PCR. Results Compression of H-PDLFs resulted in a significant increase only in MMP-1 mRNA. In contrast, the same compressive force on D-PDLFs produced significant increases in the expression of MMPs-1,-7,-9 and -16. Moreover, compression of H-PDLFs resulted in down-regulation of IL-6, while IL-6 was significantly up-regulated in compressed D-PDLFs. Compression of H-PDLFs slightly up-regulated 3 and significantly down-regulated 15 inflammation-related genes, while the same treatment strongly up-regulated 21 inflammation-related genes in D-PDLFs. Conclusion These results suggest a fundamental difference in the inflammatory response of healthy versus diseased PDLFs under physiological compression. Maintenance of these characteristics in vitro suggests that these cells may be at least partly responsible for the persistence of inflammation and localized susceptibility in chronic periodontitis. [ABSTRACT FROM AUTHOR]

A bioreactor system was developed to provide high-amplitude cyclic hydrostatic compressive stress (cHSC) using compressed air mixed commercially as needed to create partial pressures of oxygen and carbon dioxide appropriate for the cells under investigation. Operating pressures as high as 300 psi are achievable in this system at cyclic speeds of up to 0.2 Hz. In this study, ligamentous fibroblasts from human periodontal ligaments (n = 6) were compressed on two consecutive days at 150 psi for 3 h each day, and the mRNA for families of extracellular matrix protein and protease isoforms was evaluated by real-time PCR array. Several integrins were significantly upregulated, most notably alpha-3 (6.4-fold), as was SPG7 (12.1-fold). Among the collagens, Co18a1 was highly upregulated at 53.5-fold, with Co16a1, Co16a2, and Co17a1 also significantly upregulated 4.4- to 8.5-fold. MMP-1 was the most affected at 122.9-fold upregulation. MMP-14 likewise increased 17.8-fold with slight reductions for the gelatinases and a significant increase of TIMP-2 at 5.8-fold. The development of this bioreactor system and its utility in characterizing periodontal ligament fibroblast mechanobiology in intermediate-term testing hold promise for better simulating the conditions of the musculoskeletal system and the large cyclic compressive stresses joints may experience in gait, exertion, and mastication. [ABSTRACT FROM AUTHOR]

Background: In healthy periodontal tissue, innate immune responses effectively confine and suppress a bacterial insult. However, a disruption of the host-bacterial equilibrium may produce an overexpression of cytokines and lead to permanent, host-mediated tissue damage. Although such periodontal destruction primarily results from activated immune mechanisms, the site-specific damage suggests that local tissues participate in these pathologic changes. Periodontal ligament fibroblasts (PDLFs) are prominent in the periodontium and are critical in homeostasis and regeneration because they have the ability to produce multiple cytokines in response to a bacterial insult. These cells could play a role in the local pathogenesis of periodontal disease. Methods: We studied alkaline phosphatase (ALP) activity, interleukin (IL)-6 production, and morphologic characteristics of cultured PDLFs that were isolated from periodontally healthy sites (H-PDLFs) and diseased sites (D-PDLFs) in humans. Quantitative analyses of 84 genes that are related to inflammation were performed using real-time polymerase chain reaction arrays. Results: A mineralizing medium induced a significant increase of ALP in H-PDLFs, but no significant enzymatic changes were detected in D-PDLFs after such treatment. The protein and gene expression of IL6 showed a significant upregulation in D-PDLFs, which also demonstrated a significant upregulation of 54% of genes in the inflammatory gene arrays. Conclusions: To our knowledge, these results represent the first biologic evidence that D-PDLFs retain uniquely inflammatory phenotypes that could maintain localized destructive signals in periodontitis. The overexpression of proinflammatory cytokines by PDLFs could amplify local inflammation by the continuous triggering of immune responses. In addition, the location of these cells could be critical in the progression of the inflammatory front into the deeper tissues. [ABSTRACT FROM AUTHOR]