Porphyromonas gingivalis Mfa1 Induces Chemokine and Cell Adhesion Molecules in Mouse Gingival Fibroblasts via Toll-Like Receptors

Porphyromonas gingivalis Mfa1 fimbriae are thought to act as adhesion factors and to direct periodontal tissue destruction but their immunomodulatory actions are poorly understood. Here, we investigated the effect of Mfa1 stimulation on the immune and metabolic mechanisms of gingival fibroblasts from periodontal connective tissue. We also determined the role of Toll-like receptor (TLR) 2 and TLR4 in Mfa1 recognition. Mfa1 increased the expression of genes encoding chemokine (C-X-C motif) ligand (CXCL) 1, CXCL3, intercellular adhesion molecule (ICAM) 1 and Selectin endothelium (E) in gingival fibroblasts, but did not have a significant effect on genes that regulate metabolism. Mfa1-stimulated up-regulation of genes was significantly suppressed in Tlr4 siRNA-transfected cells compared with that in control siRNA-transfected cells, which indicates that recognition by TLR4 is essential for immunomodulation by Mfa1. Additionally, suppression of Tlr2 expression partially attenuated the stimulatory effect of Mfa1. Overall, these results help explain the involvement of P. gingivalis Mfa1 fimbriae in the progression of periodontal disease.

Further evidence on the relationship between abdominal aortic aneurysm and periodontitis: A cross-sectional study

BACKGROUND

Periodontitis is a chronic inflammatory disease characterized by Gram-negative bacteria responsible for the degradation of tissues surrounding tooth. Moreover, periopathogens can invade the bloodstream, disseminate and promote cardiovascular disease, such as the link between Porphyromonas gingivalis and atherosclerosis. The aim of this study was to explore the relationship between the severity of periodontitis and of abdominal aortic aneurysm (AAA).

METHODS

This cross-sectional study compared patients with stable AAA (n = 30) and patients with unstable AAA (n = 31) based on aortic diameter, growth rate, and eligibility for surgical intervention. Periodontal clinical parameters were recorded as well as the Periodontal Inflamed Surface Area and the Periodontal Index for Risk of Infectiousness (PIRI). Microbiological analyses were performed on saliva and supragingival and subgingival plaque. Quantification of Tannerella forsythia (Tf), Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans (Aa), Fusobacterium nucleatum (Fn), and Prevotella intermedia (Pi) was done by quantitative polymerase chain reaction.

RESULTS

The two AAA groups were homogeneous for age, sex, and most risk factors except hypertension and chronic obstructive pulmonary disease. Periodontal parameters were comparable but the proportion of patients with high PIRI scores was greater in those with unstable AAA (51.6% versus 23.3%). The probing depth (PD) and the proportion of PD >6 mm were positively correlated with AAA size and thrombus volume. Several associations were found between periopathogens such as Pg and AAA diameters and volumes, but no difference could be evidenced between stable and unstable AAA groups.

CONCLUSIONS

Periodontitis was highly prevalent in both stable and unstable AAA patients. Severe and progressive periodontitis (stage IV and grade C) tended to be more frequent in the group of patients with unstable AAA. Moreover, Pg was observed in all the samples (saliva, supragingival, and subgingival plaque) and was correlated with AAA diameters and volumes. The study evidenced potential relationships between periodontitis severity and size of AAA.

A haplotypic variant at the IRGM locus and rs11747270 are related to the susceptibility for chronic periodontitis

OBJECTIVE AND DESIGN

Immunity-regulated GTPase M (IRGM) plays a critical role in the defense against intracellular bacteria by regulating autophagy formation. This direct genetic association study aimed to determine whether variants at the IRGM genetic locus are associated with chronic periodontitis.

MATERIALS AND SUBJECTS

Using PCR and melting curve analysis 390 periodontitis patients and 770 healthy controls have been genotyped regarding six polymorphisms in the IRGM gene (rs13361189, rs10065172, rs4958847, rs1000113, rs11747270, rs931058).

RESULTS

Frequency distribution of alleles and genotypes for the six polymorphisms were not significantly different between the periodontitis and the control group. Also following stratification according to gender and smoking no significant linkage was found for any of the IRGM variants with periodontitis. Analysis of a subsample of patients revealed a significant association for rs11747270 with severe periodontitis (p = 0.003). Pairwise linkage analysis revealed one block composed of rs13361189, rs10065172, rs4958847, rs1000113 and 11747270 with strong or even complete linkage disequilibrium (r ² > 0.9). Four haplotypes showed a frequency of > 1%, among which the haplotype C-T-A-T-G was significantly associated with chronic periodontitis (p = 0.0051; OR 4.66, 95% CI 1.41-15.42).

CONCLUSIONS

One rare haplotype of the IRGM locus is significantly associated with chronic periodontitis in a German cohort.

Diacerein: A potential therapeutic drug for the management of experimental periodontitis in rats

Introduction:

Knowledge about the pathogenic process in the progression of periodontal disease indicates that the central cause of periodontal disease is the loss of a healthy balance between microbial virulence factors and the host’s inflammatory response. The aim of this study was to evaluate the potential effectiveness of diacerein as an anti-inflammatory drug in the management of experimental periodontitis in rats.

Methods:

The study included 60 albino rats that were divided into two groups. Periodontitis was induced in both groups. The drug group received systemic administration of diacerein, and the control group received a placebo. IL-1ß was measured two weeks after the induction of periodontitis and before the administration of the drug (baseline measurement), and it was measured again at the end of two and end of four weeks after scaling and root planning and diacerein administration.

Results:

The results indicated that there was a significant decrease in IL-1ß level in both groups. For the control group, there were significant decreases of the IL-1ß values from the baseline to two weeks and also from the baseline to four weeks, with p-values of 0.0001 for both comparisons. The same results were obtained for the drug group.

Conclusion:

It was concluded that it is likely that diacerein may play a therapeutic role as a potent anti-inflammatory drug in the management of periodontitis.

Activation of Nrf2/HO-1signaling pathway involves the anti-inflammatory activity of magnolol in Porphyromonas gingivalis lipopolysaccharide-stimulated mouse RAW 264.7 macrophages

Magnolol isolated from Magnolia officinalis, a Chinese medical herb, exhibits an anti-inflammatory activity and a protective effect against periodontitis. The inflammation caused by lipopolysaccharide (LPS) from Porphyromonas gingivalis (P. gingivalis) has been considered a key inducer in the development of periodontitis. In this study, we investigated whether magnolol inhibits P. gingivalis LPS-evoked inflammatory responses in RAW 264.7 macrophages and the involvement of heme oxygenase-1 (HO-1). Magnolol significantly activated p38 MAPK, Nrf-2/HO-1 cascade and reactive oxygen species (ROS) formation. Notably, the Nrf-2 activation and HO-1 induction by magnolol were greatly diminished by blocking p38 MAPK activity and ROS production. Furthermore, in P. gingivalis LPS-stimulated macrophages, magnolol treatment remarkably inhibited the inflammatory responses evidenced by suppression of pro-inflammatory cytokine, prostaglandin E2, nitrite formation, and the expression of inducible nitric oxide synthase and cyclooxygenase-2, as well as NF-κB activation accompanied by a significant elevation of Nrf-2 nuclear translocation and HO-1 expression/activity. However, inhibiting HO-1 activity with tin protoporphyrin IX markedly reversed the anti-inflammatory effects of magnolol. Collectively, these findings provide a novel mechanism by which magnolol inhibits P. gingivalis LPS-induced inflammation in macrophages is at least partly mediated by HO-1 activation, and thereby promoting its clinical use in periodontitis.

Abnormal pregnancy outcomes in mice using an induced periodontitis model and the haematogenous migration of Fusobacterium nucleatum sub-species to the murine placenta

Objectives

To investigate if there is subspecies specific migration to the placenta by Fusobacterium nucleatum (Fn) and to determine whether experimentally induced periodontitis results in adverse pregnancy outcomes (APO) in mice.

Methods

Periodontitis was induced in pregnant mice using an inoculum of Fn and Porphyromonas gingivalis. In parallel, four sub-species of Fn were individually injected into the circulatory system. At day 18 of gestation, the placenta, liver, spleen and blood were harvested and litter size, number of viable fetuses and resorptions, maternal, fetal and placenta weights were recorded. For the direct inoculation group, some mice were allowed to deliver for assessment of length of gestation, litter size, maternal, placental and pup weight. The presence of Fn was assessed by PCR and inflammatory mediators were measured by ELISA or multiplex analysis.

Results

Mice with alveolar bone loss, a marker of periodontitis, demonstrated significantly higher fetal weights (p = 0.015) and fetal/placental weight ratios (p = 0.030). PCR analysis of maternal organs did not identify Fn in any extracted tissues. In mice that received direct injection of Fn subspecies, varying degrees of APO were observed including preterm birth, intrauterine growth restriction, and fetal loss. Haematogenous spread of only Fn subsp. nucleatum to the placenta was confirmed. Litter size was significantly smaller (p = 0.023) and the number of resorptions was higher in inoculated versus control groups. Mice injected with subsp. nucleatum had significantly increased circulating CRP levels (p = 0.020) compared to controls while the mice with induced periodontitis had increased levels of IL-6 (p = 0.047) and IL-8 (p = 0.105).

Conclusions

Periodontitis in mice elevated fetal weight and the fetal weight/placental weight ratio. This study found that subsp. nucleatum migrated haematogenously to the placenta, leading to APO in mice. The study supports the potential role of Fn in the association between periodontitis and APO.

The complement system and its role in the pathogenesis of periodontitis: current concepts

Periodontitis is a highly prevalent inflammatory disease in tooth supporting tissues, induced by bacteria growing in a biofilm on tooth surfaces. Components of the complement system are present in the periodontal tissue and the system is activated in periodontitis. Continuous complement activation and modulation by bacteria within the biofilm in periodontal pockets, however, may enhance local tissue destruction, providing the biofilm with both essential nutrients and space to grow. A more profound understanding of the mechanisms involved in complement-derived tissue degradation may facilitate the development of new treatment concepts for periodontitis. Further studies on the role of complement in periodontitis pathogenesis may also contribute to the understanding of why some individuals fail to resolve periodontitis. Here, we review evidence that links complement to the pathogenesis of periodontitis with an emphasis on interaction of complement with bacteria from periodontitis-associated biofilm.

Magnolol ameliorates ligature-induced periodontitis in rats and osteoclastogenesis: in vivo and in vitro study

Periodontal disease characterized by alveolar bone resorption and bacterial pathogen-evoked inflammatory response has been believed to have an important impact on human oral health. The aim of this study was to evaluate whether magnolol, a main constituent of Magnolia officinalis, could inhibit the pathological features in ligature-induced periodontitis in rats and osteoclastogenesis. The sterile, 3–0 (diameter; 0.2 mm) black braided silk thread, was placed around the cervix of the upper second molars bilaterally and knotted medially to induce periodontitis. The morphological changes around the ligated molars and alveolar bone were examined by micro-CT. The distances between the amelocemental junction and the alveolar crest of the upper second molars bilaterally were measured to evaluate the alveolar bone loss. Administration of magnolol (100 mg/kg, p.o.) significantly inhibited alveolar bone resorption, the number of osteoclasts on bony surface, and protein expression of receptor activator of nuclear factor-κB ligand (RANKL), a key mediator promoting osteoclast differentiation, in ligated rats. Moreover, the ligature-induced neutrophil infiltration, expression of inducible nitric oxide synthase, cyclooxygenase-2, matrix metalloproteinase (MMP)-1 and MMP-9, superoxide formation, and nuclear factor-κB activation in inflamed gingival tissues were all attenuated by magnolol. In the in vitro study, magnolol also inhibited the growth of Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans that are key pathogens initiating periodontal disease. Furthermore, magnolol dose dependently reduced RANKL-induced osteoclast differentiation from RAW264.7 macrophages, tartrate-resistant acid phosphatase (TRAP) activity of differentiated cells accompanied by a significant attenuation of resorption pit area caused by osteoclasts. Collectively, we demonstrated for the first time that magnolol significantly ameliorates the alveolar bone loss in ligature-induced experimental periodontitis by suppressing periodontopathic microorganism accumulation, NF-κB-mediated inflammatory mediator synthesis, RANKL formation, and osteoclastogenesis. These activities support that magnolol is a potential agent to treat periodontal disease.

Diacerein: a potential therapeutic drug for periodontal disease

Periodontal diseases are chronic inflammatory diseases characterized by the destruction of the tooth-supporting structures. They are the most prevalent form of bone pathology in humans and act as a modifying factor of the systemic health of patients. Accumulating evidence has provided insight into mechanisms of periodontal inflammation revealing that oral pathogens induce inflammatory cascades, including a variety of cytokines produced by different cell types, which promotes host-mediated tissue destruction. Cytokine networks established in diseased periodontal tissues are extremely complex, and substances regulating immuno-inflammatory reactions and signaling pathways, in addition to traditional periodontal treatment, could potentially be targeted as an approach for prevention and treatment of periodontal diseases. Diacerein, a purified anthraquinone derivative, was derived originally from plants with profound anti-inflammatory and analgesic activities. Its wide range of biological activities have been applied and discussed for several decades; however, studies of diacerein have mainly concentrated on effects on joint-derived tissues/cells, which suggest a beneficial role in osteoarthritis treatment. Diacerein reduces association of the IL-1 receptor to form heterodimer complexes, repressing IL-1 and its related downstream events and impairing active IL-1 release due to the inhibition of the IL-1-converting enzyme (ICE). To date, there are no reports describing the therapeutic effect of diacerein for treatment of periodontitis. Given the involvement of inflammation and occurrence of tissue destruction in periodontal disease, we propose that diacerein might be a promising biological drug for periodontal disease due to its therapeutic advantages. In addition, we hypothesize that the underlying mechanisms might involve the capacity of diacerein to selectively inhibit signal transduction to affect the cytokine profiles and, consequently, produce the outcome of ameliorating disease breakdown.

Quantification of subgingival bacterial pathogens at different stages of periodontal diseases

Anaerobic gram-negative oral bacteria such as Treponema denticola, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Campylobacter rectus, and Fusobacterium nucleatum are closely associated with periodontal diseases. We measured the relative population (bacterial levels) of these oral pathogens in subgingival tissues of patients at different stages of Korean chronic periodontal diseases. We divided the individuals into those with chronic gingivitis (G), moderate periodontitis (P1), severe periodontitis (P2), and normal individuals (N) (n = 20 for each group) and subgingival tissue samples were collected. We used real-time PCR with TaqMan probes to evaluate the change of periodontal pathogens among different stages of periodontitis. Bacterial levels of A. actinomycetemcomitans and C. rectus are significantly increased in individuals with chronic gingivitis and moderate periodontitis, but unchanged in severe periodontitis patients. These results suggest that analyzing certain bacterial levels among total oral pathogens may facilitate understanding of the role of periodontal bacteria in the early stages of periodontitis.