Porphyromonas gingivalis induce apoptosis in human gingival epithelial cells through a gingipain-dependent mechanism

<p>Abstract</p> <p>Background</p> <p>The oral pathogen <it>Porphyromonas gingivalis </it>has been shown to modulate apoptosis in different cell types, but its effect on epithelial cells remains unclear.</p> <p>Results</p> <p>We demonstrate that primary human gingival epithelial cells (HGECs) challenged with live <it>P. gingivalis </it>for 24 hours exhibit apoptosis, and we characterize this by M30 epitope detection, caspase-3 activity, DNA fragmentation and Annexin-V staining. Live bacteria strongly upregulated intrinsic and extrinsic apoptotic pathways. Pro-apoptotic molecules such as caspase-3, -8, -9, Bid and Bax were upregulated after 24 hours. The anti-apoptotic Bcl-2 was also upregulated, but this was not sufficient to ensure cell survival. The main <it>P. gingivalis </it>proteases arginine and lysine gingipains are necessary and sufficient to induce host cell apoptosis. Thus, live <it>P. gingivalis </it>can invoke gingival epithelial cell apoptosis in a time and dose dependent manner with significant apoptosis occurring between 12 and 24 hours of challenge via a gingipain-dependent mechanism.</p> <p>Conclusion</p> <p>The present study provides evidence that live, but not heat-killed, <it>P. gingivalis </it>can induce apoptosis after 24 hours of challenge in primary human gingival epithelial cells. Either arginine or lysine gingipains are necessary and sufficient factors in <it>P. gingivalis </it>elicited apoptosis.</p

In vitro modeling of host-parasite interactions: the 'subgingival' biofilm challenge of primary human epithelial cells

BACKGROUND: Microbial biofilms are known to cause an increasing number of chronic inflammatory and infectious conditions. A classical example is chronic periodontal disease, a condition initiated by the subgingival dental plaque biofilm on gingival epithelial tissues. We describe here a new model that permits the examination of interactions between the bacterial biofilm and host cells in general. We use primary human gingival epithelial cells (HGEC) and an in vitro grown biofilm, comprising nine frequently studied and representative subgingival plaque bacteria. RESULTS: We describe the growth of a mature 'subgingival' in vitro biofilm, its composition during development, its ability to adapt to aerobic conditions and how we expose in vitro a HGEC monolayer to this biofilm.Challenging the host derived HGEC with the biofilm invoked apoptosis in the epithelial cells, triggered release of pro-inflammatory cytokines and in parallel induced rapid degradation of the cytokines by biofilm-generated enzymes. CONCLUSION: We developed an experimental in vitro model to study processes taking place in the gingival crevice during the initiation of inflammation. The new model takes into account that the microbial challenge derives from a biofilm community and not from planktonically cultured bacterial strains. It will facilitate easily the introduction of additional host cells such as neutrophils for future biofilm:host cell challenge studies. Our methodology may generate particular interest, as it should be widely applicable to other biofilm-related chronic inflammatory diseases

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Unraveling the Lipolytic Activity of Thermophilic Bacteria Isolated from a Volcanic Environment

In a bioprospecting effort towards novel thermostable lipases, we assessed the lipolytic profile of 101 bacterial strains isolated from the volcanic area of Santorini, Aegean Sea, Greece. Screening of lipase activity was performed both in agar plates and liquid cultures using olive oil as carbon source. Significant differences were observed between the two screening methods with no clear correlation between them. While the percentage of lipase producing strains identified in agar plates was only 17%, lipolytic activity in liquid culture supernatants was detected for 74% of them. Nine strains exhibiting elevated extracellular lipase activities were selected for lipase production and biochemical characterization. The majority of lipase producers revealed high phylogenetic similarity with Geobacillus species and related genera, whilst one of them was identified as Aneurinibacillus sp. Lipase biosynthesis strongly depended on the carbon source that supplemented the culture medium. Olive oil induced lipase production in all strains, but maximum enzyme yields for some of the strains were also obtained with Tween-80, mineral oil, and glycerol. Partially purified lipases revealed optimal activity at 70–80°C and pH 8-9. Extensive thermal stability studies revealed marked thermostability for the majority of the lipases as well as a two-step thermal deactivation pattern

Effects of Conventional Synthetic Disease-Modifying Antirheumatic Drugs on Response to Periodontal Treatment in Patients with Rheumatoid Arthritis

Rheumatoid arthritis (RA) and periodontitis are common chronic inflammatory diseases and periodontitis is known to be more common and more severe in patients with RA. Based on a paucity of studies about the relationship between common conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) and periodontitis, this prospective study aimed to evaluate the adjunctive effect of csDMARDs on response to nonsurgical periodontal treatment in patients with RA. Thirty-two patients with RA (RA group) and 32 systemically healthy patients (control group) with periodontitis were included in this study. The RA group patients were treated with csDMARDs, such as methotrexate, hydroxychloroquine, and sulfasalazine. Conventional nonsurgical periodontal treatment with scaling and root planing was performed in both groups. The extent and severity of periodontitis were evaluated by plaque index (PI), gingival index (GI), probing depth (PD), clinical attachment level (CAL), and bleeding on probing (BOP) at baseline and 4 weeks after periodontal treatment. There was no statistically significant difference of periodontal parameters between the RA and control groups at baseline. Four weeks after scaling and root planing, PD reduction, and CAL gain were higher in the RA group treated with csDMARDs compared to the control group, and the difference was statistically significant (P = 0.006 and 0.003, respectively). A post hoc analysis of the RA group showed no statistically significant difference on the response to nonsurgical periodontal treatment in multiple csDMARDs therapy and addition of NSAIDs and/or steroids to csDMARDs. In patients with RA, csDMARDs showed beneficial effect on periodontal clinical parameters following the nonsurgical periodontal treatment