Animal Models to Study Host-Bacteria Interactions Involved in Periodontitis

Animal models have distinct advantages because they can mimic cellular complexities that occur in humans in vivo and are often more accurate than in vitro studies that take place on plastic surfaces with limited numbers of cell types present. Furthermore, cause and effect relationships can be established by applying inhibitors or activators or through the use of genetically modified animals. Such gain or loss of function studies are often difficult to achieve in human clinical studies, particularly in obtaining target tissue due to important ethical considerations. Animal models in periodontal disease are particularly important at this point in the development of the scientific basis for understanding the predominant pathological processes. Periodontal disease can be broken down into discrete steps, each of which may be studied separately depending upon the animal model. These steps involve the development of a pathogenic biofilm, invasion of connective tissue by bacteria or their products, induction of a destructive host response in connective tissue and limitation of are pair process that follows tissue breakdown. Animal studies can test hypotheses related to each of these steps, and should be evaluated by their capacity to test a specific hypothesis rather than recapitulating all aspects of periodontal disease. Thus, each of the models described below can be adapted to test discrete components of the pathological process of periodontal disease, but not necessarily all of them

Clopidogrel Enhances Periodontal Repair in Rats Through Decreased Inflammation

Aim We hypothesized that platelet inactivation induced by drugs might interfere with periodontal repair in experimental periodontitis by suppressing the release of biological mediators from platelets at the site of injury. Material and Methods 60 rats were randomly assigned to 6 groups (n=10) and ligatures were placed around lower first molars of three groups. The other three groups were used as negative controls. Ligatures were removed after 10 days of periodontitis induction and all groups were submitted to treatment with aspirin (Asp) (30 mg/kg), clopidogrel (Clop) (75 mg/kg) or NaCl 0.9% intragastrically once daily for 3 days. Periodontal tissue was assessed by the measurement of CXCL12, CXCL4, CCL5 and PDGF by ELISA; histomorphometric analysis of PMN infiltration, attachment loss, bone loss and osteoclast numbers and quantification of blood vessels by imunnohistochemistry. Results During periodontal repair and treatment with NaCl 0.9%, CCL5 was decreased and CXCL12 increased when compared to negative control groups. Asp and Clop did not affect CCL5 expression, decreased CXCL12 but only Clop decreased CXCL4 and PDGF content compared to saline-treated animals. Clop increased blood vessel number, reduced PMN count, and decreased attachment and bone loss, also decreased osteoclast number in animals submitted or not to periodontal repair. Conclusion Systemic administration of Clop during 3 days improved the repair process associated with experimental periodontal disease, suggesting that it may have therapeutic value under situations where tissues undergo a transition from inflammation to repair

Expression of interferon-γ, interferon-α and related genes in individuals with Down syndrome and periodontitis

AbstractBackgroundRecently, attenuation of anti-inflammatory and increase of pro-inflammatory mediators was demonstrated in individuals with Down syndrome (DS) in comparison with euploid patients during periodontal disease (PD), suggesting a shift to a more aggressive inflammation in DS.AimTo determine the influence of DS in the modulation of interferons (IFNs) signaling pathway in PD.Materials and methodsClinical periodontal assessment was performed and gingival tissue samples obtained from a total of 51 subjects, including 19 DS individuals with PD, 20 euploid individuals with PD and 12 euploid individuals without PD. Expression levels of interferon-gamma (IFNG) and interferon-alpha (IFNA), and their receptors IFNGR1, IFNGR2, IFNAR1 and IFNAR2, the signaling intermediates Janus kinase 1 (JAK1), signal transducer and activator of transcription 1 (STAT1) and interferon regulatory factor 1 (IRF1) were determined using real time quantitative polymerase chain reaction (qPCR).ResultsClinical signs of periodontal disease were markedly more severe in DS and euploid patients with PD in comparison to euploid and periodontally healthy patients. There was no difference on mRNA levels of IFNA, IFNG, INFGR2, IFNAR1 and IFNAR2 between DS and euploid individuals, even though some of these genes are located on chromosome 21. STAT1 and IRF1 mRNA levels were significantly lower in DS patients in comparison with euploid individuals with PD. In euploid individuals, PD was associated with an increased expression of IFNGR1, IFNGR2, IFNAR1, STAT1 and IRF1.ConclusionsReduced expression of STAT1 and IRF1 genes indicate an impaired activation of IFNs signaling in individuals with DS and PD. Expression of IFNA, IFNG and IFN receptors was not altered in DS patients, indicating that indirect mechanisms are involved in the reduced activation of IFN signaling

Diabetes and Increased Lipid Peroxidation are Associated with Systemic Inflammation Even in Well-Controlled Patients

Background The effect of the interaction between type 2 diabetes and dyslipidemia on inflammation and lipid peroxidation (LPO) has not been assessed. Aim To investigate whether diabetes coupled with dyslipidemia alters oxidative metabolism leading to increased LPO products and inflammatory status. Methods 100 patients were divided into four groups based upon diabetic and dyslipidemic status: poorly controlled diabetes with dyslipidemia (DM-PC/D), well-controlled diabetes with dyslipidemia (DM-WC/D), normoglycemic individuals with dyslipidemia (NG/D), and normoglycemic individuals without dyslipidemia (NG/ND). Plasma was evaluated for an LPO product (MDA), antioxidant levels and inflammatory cytokines. Results Diabetics presented significantly higher levels of LPO (p \u3c 0.05) and the DM-PC/D had higher levels of proinflammatory cytokines and MDA in the plasma in comparison with normoglycemics (p \u3c 0.05). Interestingly IL1-β, IL-6, and TNF-α in DM-WC/D were not statistically different from those in DM-PC/D. Normoglycemic individuals with dyslipidemia presented significantly increased levels of IL-6 and TNF-α when compared to normoglycemic without dyslipidemia (p \u3c 0.05). MDA levels were also positively correlated with the presence of DM complications (r = 0.42, p \u3c 0.01). Conclusions These findings show that dyslipidemia is associated with an increased inflammatory status, even in well-controlled diabetics and in normoglycemics. Our results suggest that lipid metabolism and peroxidation are important for the development of inflammation, which is elevated in several complications associated with diabetes

Periodontal condition in patients with rheumatoid arthritis

The purpose of this clinical study was to investigate if periodontal disease and rheumatoid arthritis (RA) are associated. The study included 39 RA patients (test group) and 22 age- and gender-matched healthy individuals (control group). Questionnaires on general and oral health were applied and a complete periodontal exam, including visible plaque, marginal bleeding, attachment loss (AL) and number of teeth present, was also performed by a single calibrated examiner. Diabetes mellitus patients and smokers were excluded. RA patients had fewer teeth, higher prevalence of sites presenting dental plaque and a higher frequency of sites with advanced attachment loss. Although the prevalence of dental plaque was higher in the test group (Chi-square test, p = 0.0006), the percentage of sites showing gingival bleeding was not different (Fisher’s exact test, p > 0.05). Based on our results, we suggest that there is an association between periodontal disease and RA

Differential effects of modulation of SOCS3 expression and STAT3 inhibition on HNSCC migration.

<p>(A) Representative phase-contrast images of the in vitro wound area in the different cell cultures (100×magnification) for the gain of function experiments by transfection of a CMV-driven SOCS3 expression plasmid or the empty vector control. STAT3 biochemical inhibitor was used to assess possible effects of SOCS3 that are independent of modulation of STAT3 activity. The distance between the edges of the wound was measured on digital images captured adjacent to the reference notch made in the cell culture plastic (black area on the right of the images) Non-neoplastic HaCAT cells were transfected with the empty vector to control for non-specific effects of the transfection procedure on cell migration. Bars represent averages and vertical lines standard deviation of three independent wounding experiments, measured in triplicate (*p<0.05 indicates significant difference in comparison to the distance between edges of the wound at the same time period in empty-vector transfected cells). (B) Representative phase-contrast images of the in vitro wound area in the loss of function experiments by transfection of SOCS3 siRNA or non-targeting siRNA in OSCC3 cells. Quantitation of cell migration was performed as described in (A) and the graph represent average and standard deviations of three independent wounding experiments measured in triplicate.</p