Molecular microbiological evaluation of subgingival biofilm sampling by paper point and curette

The present clinical study aimed to investigate if there are differences in microbiological outcomes dependent on the subgingival biofilm collection method. Subgingival biofilm samples were collected from the four deepest pockets (>5 mm) of 17 patients with aggressive periodontitis (AgP) and 33 patients with chronic periodontitis (CP), first by paper point and thereafter by curette. Samples obtained with the same method were pooled together from each patient and forwarded for molecular microbiological analysis by a commercially available assay (IAI Pado Test 4.5) that estimates total bacterial load and levels of Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and Aggregatibacter actinomycetemcomitans. Data analysis included frequency of detection, quantification and correlation of detection levels between the two sampling methods. P. gingivalis, T. forsythia and T. denticola were detected in >90% of the samples, and their detection levels exhibited a strong correlation between sampling methods. The detection consistency of A. actinomycetemcomitans was 56% between the two sampling methods. A. actinomycetemcomitans was more readily detected by paper point compared with curette collection with a stronger correlation between the two methods in AgP. Subgingival biofilm sampling by curette or paper point does not yield differences in the detection of the three ‘red complex’ species. However, A. actinomycetemcomitans was more consistently detected by means of paper point collection, which can be crucial in the decision to administer antibiotics as an adjunctive periodontal treatment.     

Differential ability of periodontopathic bacteria to modulate invasion of human gingival epithelial cells by Porphyromonas gingivalis

Periodontitis is a polymicrobial infection caused by selected gram-negative bacteria including Porphyromonas gingivalis. Host cell invasion by P. gingivalis has been proposed as a possible mechanism of pathogenesis in periodontitis. The aim of the present study was to assess the influence of periodontopathogens on P. gingivalis invasion of gingival epithelial cells in polymicrobial infection. P. gingivalis was tested for its ability to invade a human gingival epithelial cell line Ca9-22 in co-infection with periodontopathogens, using an antibiotic protection assay. Among the pathogens tested, only Fusobacterium nucleatum demonstrated the ability to significantly promote P. gingivalis invasion (P < 0.01). This increased invasion was confirmed by confocal scanning laser microscopy utilizing a dual labeling technique. In contrast, co-infection with Aggregatibacter actinomycetemcomitans or Tannerella forsythia attenuated P. gingivalis invasion. The fusobacterial enhancement of host cell invasion was not observed in co-incubation with other periodontopathogens tested. These results suggested that complex synergistic or antagonistic physiologic mechanisms are intimately involved in host cell invasion by P. gingivalis in polymicrobial infection.     

Prevalence of Aggregatibacter actinomycetemcomitans,Porphyromonas gingivalis and Tannerella forsythia in Japanese patients with generalized chronic and aggressive periodontitis

This study aimed to investigate the prevalence and levels of major periodontal pathogens, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Tannerella forsythia in subgingival plaque samples of a group of Japanese patients with aggressive periodontitis (AgP) and chronic periodontitis (CP). A total of 40 patients with clinical diagnosis of AgP or CP and 10 periodontally healthy volunteers were subjected to clinical and microbiological analysis. Subgingival plaque samples were analyzed for A. actinomycetemcomitans, P. gingivalis and T. forsythia with a real-time polymerase chain reaction (PCR) technique. The prevalence of P. gingivalis and T. forsythia was relatively high in patients with periodontitis: over 60% of AgP or CP patients harbored these pathogens whereas they were not detected in the subgingival plaque samples from periodontally healthy individuals. P. gingivalis and T. forsythia were relatively frequently detected together in AgP and CP patients. No significant differences in the prevalence or level of the 3 pathogens were found between periodontitis groups. The proportion of T. forsythia was approximately 4-fold higher in CP group than in AgP group (P = 0.02). In periodontitis patients, a significant positive correlation was found between periodontal parameters (probing depth and clinical attachment level) and the numbers of total bacteria, P. gingivalis and T. forsythia. No distinct pattern of the subgingival profile of these pathogens was discerned between the two disease entities, except for the difference in the proportion of T. forsythia. The red complex bacteria, P. gingivalis and T. forsythia were highly prevalent in this population of Japanese AgP and CP patients, collaborating their roles in periodontitis.     

Are Putative Periodontal Pathogens Reliable Diagnostic Markers?

Periodontitis is one of the most common chronic inflammatory diseases. A number of putative bacterial pathogens have been associated with the disease and are used as diagnostic markers. In the present study, we compared the prevalence of oral bacterial species in the subgingival biofilm of generalized aggressive periodontitis (GAP) (n = 44) and chronic periodontitis (CP) (n = 46) patients with that of a periodontitis-resistant control group (PR) (n = 21). The control group consisted of subjects at least 65 years of age with only minimal or no periodontitis and no history of periodontal treatment. A total of 555 samples from 111 subjects were included in this study. The samples were analyzed by PCR of 16S rRNA gene fragments and subsequent dot blot hybridization using oligonucleotide probes specific for Aggregatibacter (Actinobacillus) actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, a Treponema denticola-like phylogroup (Treponema phylogroup II), Treponema lecithinolyticum, Campylobacter rectus, Fusobacterium spp., and Fusobacterium nucleatum, as well as Capnocytophaga ochracea. Our data confirm a high prevalence of the putative periodontal pathogens P. gingivalis, P. intermedia, and T. forsythia in the periodontitis groups. However, these species were also frequently detected in the PR group. For most of the species tested, the prevalence was more associated with increased probing depth than with the subject group. T. lecithinolyticum was the only periodontopathogenic species showing significant differences both between GAP and CP patients and between GAP patients and PR subjects. C. ochracea was associated with the PR subjects, regardless of the probing depth. These results indicate that T. lecithinolyticum may be a diagnostic marker for GAP and C. ochracea for periodontal health. They also suggest that current presumptions of the association of specific bacteria with periodontal health and disease require further evaluation.Periodontitis is a chronic inflammatory disease of infectious origin leading to destruction of tooth-supporting tissues and is the major cause of tooth loss in adults. However, all patients are not equally susceptible to periodontitis. In addition to the microbial challenge, other factors, such as genetics, environment, and host factors, play a role in the pathogenesis of this disease (24). The most common form is chronic periodontitis, which is characterized by a slow, gradual loss of periodontal attachment (3). In contrast to this form, rapid destruction of periodontal attachment is evident in aggressive periodontitis. Generalized aggressive periodontitis usually affects young adults under the age of 30, with attachment loss occurring in pronounced episodes of tissue destruction (2).Many studies have been performed to evaluate the composition of the subgingival biofilm and identify key periodontal pathogens by both cultivation and molecular methods. More than 700 different species have been identified in the oral cavity, many of which are yet to be cultivated (1, 25). Of these species, only a small number are suspected periodontal pathogens, such as Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola. This group of bacteria, characterized as the “red complex,” was highly associated with periodontal tissue destruction (28). Other bacteria, such as Prevotella intermedia, Campylobacter rectus, Fusobacterium species, Peptostreptococcus micros, and various spirochetes, have been implicated in the development of periodontitis (33). Aggressive periodontitis has been postulated to be frequently associated with Aggregatibacter actinomycetemcomitans and P. gingivalis (2). Localized aggressive periodontitis in particular seems to be characterized by specific infection with A. actinomycetemcomitans (27, 34), whereas chronic periodontitis is rather a mixed bacterial infection, not associated with any specific microorganism.In the present study, we reevaluated the association of putative periodontal pathogens in patients with generalized aggressive or chronic periodontitis versus species in a periodontitis-resistant control group to identify species which are incompatible with periodontal health. As a control group, we chose a population of older adults with only minimal or no periodontitis and no history of periodontal treatment, considering these subjects resistant to periodontitis. We analyzed the presence of A. actinomycetemcomitans, P. gingivalis, P. intermedia, T. forsythia, a T. denticola-like phylogroup (Treponema phylogroup II), Treponema lecithinolyticum, C. rectus, Fusobacterium spp., and Fusobacterium nucleatum, as well as Capnocytophaga ochracea. We also examined whether the presence or absence of these species was related to pocket depth.     

Periodontal Disease in Patients with Psoriatic Arthritis

Rheumatological diseases and periodontal disease are both characterized by dysregulation of the host inflammatory response. The aim of this study was to determine the possible relationship between periodontitis and psoriatic arthritis (PsA). Fifty-one adults with PsA (27 men and 24 women; mean age 41.73?±?11.27 years) and 50 age- and gender-balanced systemically healthy control subjects participated in the study. Participants' periodontal status as determined by probing pocket depth, clinical attachment loss (CAL), plaque index, and gingival index was evaluated. The CAL levels of the PsA group were significantly higher than those of the control group (p?<?0.05) There were no statistically significant differences in the frequency of periodontitis, probing pocket depth, plaque index, or gingival index between the two groups. The results of the present study show that periodontitis severity as determined by CAL was higher in the PsA group; therefore, periodontal evaluation must be considered when PsA is diagnosed.     

Role of the NK Cell-Activating Receptor CRACC in Periodontitis

Periodontitis is a highly prevalent, biofilm-mediated chronic inflammatory disease that results in the loss of the tooth-supporting tissues. It features two major clinical entities: chronic periodontitis, which is more common, and aggressive periodontitis, which usually has an early onset and a rapid progression. Natural killer (NK) cells are a distinct subgroup of lymphocytes that play a major role in the ability of the innate immune system to steer immune responses. NK cells are abundant in periodontitis lesions, and NK cell activation has been causally linked to periodontal tissue destruction. However, the exact mechanisms of their activation and their role in the pathophysiology of periodontitis are elusive. Here, we show that the predominant NK cell-activating molecule in periodontitis is CD2-like receptor activating cytotoxic cells (CRACC). We show that CRACC induction was significantly more pronounced in aggressive than chronic periodontitis and correlated positively with periodontal disease severity, subgingival levels of specific periodontal pathogens, and NK cell activation in vivo. We delineate how Aggregatibacter actinomycetemcomitans, an oral pathogen that is causally associated with aggressive periodontitis, indirectly induces CRACC on NK cells via activation of dendritic cells and subsequent interleukin 12 (IL-12) signaling. In contrast, we demonstrate that fimbriae from Porphyromonas gingivalis, a principal pathogen in chronic periodontitis, actively attenuate CRACC induction on NK cells. Our data suggest an involvement of CRACC-mediated NK cell activation in periodontal tissue destruction and point to a plausible distinction in the pathobiology of aggressive and chronic periodontitis that may help explain the accelerated tissue destruction in aggressive periodontitis.     

Differential ability of periodontopathic bacteria to modulate invasion of human gingival epithelial cells by Porphyromonas gingivalis

Periodontitis is a polymicrobial infection caused by selected gram-negative bacteria including Porphyromonas gingivalis. Host cell invasion by P. gingivalis has been proposed as a possible mechanism of pathogenesis in periodontitis. The aim of the present study was to assess the influence of periodontopathogens on P. gingivalis invasion of gingival epithelial cells in polymicrobial infection. P. gingivalis was tested for its ability to invade a human gingival epithelial cell line Ca9-22 in co-infection with periodontopathogens, using an antibiotic protection assay. Among the pathogens tested, only Fusobacterium nucleatum demonstrated the ability to significantly promote P. gingivalis invasion (P < 0.01). This increased invasion was confirmed by confocal scanning laser microscopy utilizing a dual labeling technique. In contrast, co-infection with Aggregatibacter actinomycetemcomitans or Tannerella forsythia attenuated P. gingivalis invasion. The fusobacterial enhancement of host cell invasion was not observed in co-incubation with other periodontopathogens tested. These results suggested that complex synergistic or antagonistic physiologic mechanisms are intimately involved in host cell invasion by P. gingivalis in polymicrobial infection.     

Prevalence of Porphyromonas gingivalis and Periodontal Health Status

Periodontitis is a common, progressive disease that eventually affects the majority of the population. The local destruction of periodontitis is believed to result from a bacterial infection of the gingival sulcus, and several clinical studies have provided evidence to implicate Porphyromonas gingivalis. If P. gingivalis is a periodontal pathogen, it would be expected to be present in most subjects with disease and rarely detected in subjects with good periodontal health. However, in most previous studies, P. gingivalis has not been detected in the majority of subjects with disease, and age-matched, periodontally healthy controls were not included for comparison. The purpose of the study reported here was to compare the prevalence of P. gingivalis in a group with periodontitis to that of a group that is periodontally healthy. A comprehensive sampling strategy and a sensitive PCR assay were used to maximize the likelihood of detection. The target sequence for P. gingivalis-specific amplification was the transcribed spacer region within the ribosomal operon. P. gingivalis was detected in only 25% (46 of 181) of the healthy subjects but was detected in 79% (103 of 130) of the periodontitis group (P < 0.0001). The odds ratio for being infected with P. gingivalis was 11.2 times greater in the periodontitis group than in the healthy group (95% confidence interval, 6.5 to 19.2). These data implicate P. gingivalis in the pathogenesis of periodontitis and suggest that P. gingivalis may not be a normal inhabitant of a periodontally healthy dentition.     

Gingival Crevicular Fluid and Salivary Periostin Levels in Non-Smoker Subjects With Chronic and Aggressive Periodontitis

Periostin, an extracellular matrix protein functioning as an important structural mediator and adhesion molecule, has been shown to be an important regulator of connective tissue integrity. This study aimed to evaluate the levels of periostin in chronic periodontitis (CP) and aggressive periodontitis (AgP) compared to non-periodontitis (NP). Individuals were submitted to gingival crevicular fluid (GCF) and saliva sampling. Periodontal examination consisted of plaque index (PI), gingival index (GI), probing depth (PD), bleeding on probing (BOP), and clinical attachment level (CAL) measurements. Assays for periostin were performed by an enzyme-linked immunosorbent assay. Periodontitis patients presented more severe clinical indices compared to the NP group (p?<?0.001). The mean GCF level of periostin was lowest in the AgP group as compared to the other groups and was lower in the CP group as compared to the NP group (p?<?0.001). Increased levels of periostin were observed in the saliva of patients with AgP as compared to the CP and NP groups (p?<?0.05). There was a negative relationship between GCF periostin levels and clinical parameters (p?<?0.01), whereas a positive correlation was observed between salivary periostin levels and full-mouth GI and CAL scores (p?<?0.01). To our knowledge, this is the first report investigating periostin levels in GCF and saliva in aggressive periodontitis. The results suggest that subjects with CP and AgP exhibit a different periostin profile. Periostin in GCF may have a protective role against periodontal disease. Furthermore, salivary periostin concentrations may have a promising diagnostic potential for the aggressive forms of periodontal disease.     

Porphyromonas gingivalis induces RANKL in bone marrow stromal cells: involvement of the p38 MAPK

Periodontitis is a bacterially-induced oral inflammatory disease that is characterised by tissue degradation and bone loss. Porphyromonas gingivalis is a gram negative bacterial species highly associated with the pathogenesis of chronic periodontitis. Receptor activator of nuclear factor-kB ligand (RANKL) induces bone resorption whilst osteoprotegerin (OPG) is a decoy receptor that blocks this process. Cyclooxygenase-2 (COX-2) is an enzyme responsible for the production of prostaglandin (PGE)_2, which is a major inflammatory mediator of bone resorption. Mitogen-activated protein kinases (MAPK) are intracellular signalling molecules involved in various cell processes, including inflammation. This study aimed to investigate the effect of P. gingivalis on MAPKs and their involvement in the regulation of RANKL, OPG and COX-2 expression in bone marrow stromal cells. P. gingivalis challenge resulted in the phosphorylation of primarily the p38 MAPK. RANKL and COX-2 mRNA expressions were up-regulated, whereas OPG was down-regulated by P. gingivalis. The p38 synthetic inhibitor SB203580 abolished the P. gingivalis-induced RANKL and COX-2 expression, but did not affect OPG. Collectively, these results suggest that the p38 MAPK pathway is involved in the induction of RANKL and COX-2 by P. gingivalis, providing further insights into the pathogenic mechanisms of periodontitis.     

Association between type 1 diabetes and periodontal health

PurposeWe assessed periodontal status in patients with type 1 diabetes and healthy individuals in relation to their glycemic control, smoking and inflammatory biomarkers.Material/methodsPeriodontal status was examined in 107 patients with diabetes and 40 controls, using Oral Hygiene Index (OHI), Community Periodontal Index (CPI) and tooth number. CPI values of 0–2 and 3–4 were classified as non-periodontitis and periodontitis, respectively. Blood samples were analyzed for glucose, HbA1c, CRP, fibrinogen, interleukin-1 and tumor necrosis factor-alpha (TNF-α).ResultsPeriodontitis was found in 15.0% of the controls and 57.9% of diabetic patients, including 40.0% of these with good metabolic control (GMC) and 59.5% of those with poor metabolic control (PMC). Severe periodontitis was more frequent in the PMC than in the GMC group and in the controls (26.0% vs. 20.0% vs. 5.0%). The PMC patients had lower number of sextants with CPI 0 and higher number of sextants with CPI 3 and CPI 4 as well as lower tooth number in comparison with the controls. The patients with periodontitis had higher TNF-α (p < 0.001) and OHI (p < 0.001) than the patients without periodontitis. The number of sextants with CPI 0 correlated negatively with fibrinogen and TNF-α levels, whereas the number of sextants with CPI 3 correlated positively with TNF-α and fasting glucose level.ConclusionsThere is good evidence that type 1 diabetes increases the risk of periodontal disease. Our results suggest that poor metabolic control of diabetes together with smoking and inadequate oral hygiene increase the risk of severe periodontal destruction in patients with type 1 diabetes.     

MMP-8 and TIMP-1 are associated to periodontal inflammation in patients with rheumatoid arthritis under methotrexate immunosuppression – First results of a cross-sectional study

BackgroundAim of this cross-sectional study was the investigation of associations between different rheumatoid arthritis (RA)-related blood parameters and periodontal condition as well as selected periodontal pathogenic bacteria in RA patients under methotrexate (MTX) immunosuppression.MethodsPeriodontal probing depth (PPD), bleeding on probing (BOP) and clinical attachment loss (CAL) were assessed. Periodontal condition was classified into: no/mild and moderate or severe periodontitis (P). Prevalence of selected periodontal pathogenic bacteria and concentration of matrix metalloproteinase 8 (MMP-8) was assessed from the gingival crevicular fluid (GCF) using PCR and ELISA, respectively. Blood samples were analyzed for the concentration of selected rheumatoid parameters. Statistical analysis: t-test, Mann–Whitney-U-Test, exact Fisher tests or chi square test (p < 0.05).ResultsFifty-six patients (mean age 55.07 years, 34 P, 22 no P) were included. While prevalence of periodontal pathogenic bacteria was higher in P patients, no substantial association of bacteria with blood parameters was found. In periodontal diseased participants, MMP-8 concentration in GCF (6.22 ± 7.01 vs. 15.99 ± 13.49; p < 0.01) and blood (2.60 ± 3.57 vs. 5.52 ± 5.92; p < 0.01) was increased, while no correlation between GCF and blood was found (Spearman's rho: 0.175; p = 0.23). Furthermore, higher blood concentrations of MMP-8 and tissue inhibitor of MMP (TIMP-1) were detected in patients with increased periodontal inflammation (BOP positive, p < 0.01).ConclusionPeriodontal inflammation appears associated to MMP-8 and TIMP-1 in blood. Thereby, clinical interaction between periodontal conditions, periodontal pathogenic bacteria and RA-related cytokines remain unclear.     

高压氧疗法对大鼠心理应激相关牙周炎治疗作用及低氧诱导因子1α表达的研究

 目的: 探讨高压氧(hyperbaric oxygen,HBO)治疗对心理应激相关牙周炎牙周组织低氧诱导因子1α(hypoxia-inducible factor-1α,HIF-1α)表达的影响。方法: 清洁级4周龄雄性Wistar大鼠120只,随机分为4组:正常对照组;单纯应激组;牙周炎组:用浸有牙龈卟啉单胞菌株的丝线结扎左侧上颌第二磨牙牙颈部,复制实验性牙周炎模型;牙周炎+应激组。于实验后第9周停止应激刺激,对除正常对照组外其它各组大鼠每组选取6只进行HBO治疗。于实验后2、4和8周末分批处死未治疗动物,每组处死6只;于实验后10周末处死HBO治疗及未治疗动物。处死前测量术区的牙周附着情况,制作牙体牙周联合切片,观察牙周的组织学改变。免疫组化法检测各组大鼠牙周组织HIF-1α的表达水平,计算平均阳性细胞率。结果: 大体观察见正常对照组及单纯应激组牙周附着位置正常;牙周炎组出现牙龈萎缩,附着丧失明显;牙周炎+应激组附着丧失明显,根分叉暴露,HBO治疗后,牙龈水肿减轻,牙周袋变浅;组织学观察见牙周炎+应激组牙周组织破坏程度在各时点均重于牙周炎组;经HBO治疗后,牙周组织炎症程度减轻,炎症细胞浸润减少;牙龈指数(gingival index, GI)及牙周附着丧失(attachment loss, AL)检查见单纯应激组与正常对照组在各时点均无显著差异;在第4、8周时牙周炎+应激组GI、AL明显高于牙周炎组(P < 0.01);HBO治疗结束后牙周炎组及牙周炎+应激组GI、AL明显低于未治疗组(P < 0.05);单纯应激组与正常对照组HIF-1α免疫组化平均阳性细胞率在各时点均无显著差异;牙周炎+应激组HIF-1α平均阳性细胞率在第4、8周时均明显高于牙周炎组(P < 0.01);HBO治疗结束后牙周炎组及牙周炎+应激组HIF-1α平均阳性细胞率较未治疗组降低(P < 0.01)。结论: 心理应激可加重牙周组织缺氧程度从而加重牙周炎症状,HBO通过增加牙周组织的氧供应量对大鼠实验性牙周炎及心理应激相关牙周炎有显著的治疗效果。     

Use of PCR to detect <Emphasis Type="Italic">Entamoeba gingivalis</Emphasis> in diseased gingival pockets and demonstrate its absence in healthy gingival sites

Investigators using light microscopy have identified the protozoan parasite Entamoeba gingivalis from diseased gingival pockets for nearly 100 years. The objective of the present investigation was to develop a molecular biology approach for determining the presence of E. gingivalis in both diseased gingival pockets and healthy gingival sites. For this, a previously developed conventional polymerase chain reaction (PCR) was evaluated and a real-time polymerase chain reaction assay was developed. Paper points were inserted into the base of the sulcus of both diseased gingival pockets and healthy gingival sites. DNA was extracted using the QIAamp DNA mini kit, and subsequently analyzed using conventional and real-time PCR analysis. A previously described primer set specific for the small subunit ribosomal RNA gene (SSU rDNA) of E. gingivalis was used for the conventional PCR. For the real-time PCR, a primer set was designed to amplify a 135-bp fragment inside the SSU rDNA of E. gingivalis. A conventional PCR assay detected E. gingivalis in 27% of diseased gingival pockets. The real-time PCR using a different primer set detected protozoa in 69% of diseased pocket sites. Thus, the latter technique proved more sensitive for detection of E. gingivalis. No E. gingivalis were detected in any of the healthy gingival pocket sites using either type of PCR assay. Results support a concept that the presence of E. gingivalis is associated only with diseased gingival pocket sites. The newly described methodology may also serve to provide a novel eukaryotic cell marker of disease status in gingival pockets.     

Host Modulation in Rheumatoid Arthritis Patients with TNF Blockers Significantly Decreases Biochemical Parameters in Periodontitis

The aim of this study was to evaluate the effects of host modulation therapy on periodontal and biochemical parameters. Sixteen rheumatoid arthritis patients newly scheduled for anti-tumour necrosis factor (TNF) therapy were screened for 30 days. Periodontal parameters (clinical attachment level, probing pocket depth, bleeding on probing, plaque index and gingival index) as well as salivary and gingival crevicular fluid (GCF), interleukin (IL)-1β, IL-8 and monocyte chemoattractant protein-1 (MCP-1) levels of the patients were evaluated at baseline and on the 30th day of therapy. GCF volume, IL-1β and IL-8 levels (p?=?0.007, p?=?0.017 and p?=?0.009, respectively) of the periodontitis patients significantly decreased. Although there was a decrease in all these parameters in healthy patients, it was below statistical significance. Salivary IL-8 and MCP-1 levels significantly decreased in periodontitis patients (p?=?0.028 and p?=?0.013, respectively), but IL-1β levels remained unchanged. These results suggest that TNF blockers may significantly modify host response in terms of biochemical parameters of the periodontium and may mask significant associations such as those reported between periodontitis and rheumatoid arthritis.     

Expression and regulation of the NALP3 inflammasome complex in periodontal diseases

Periodontitis is an infectious process characterized by inflammation affecting the supporting structures of the teeth. Porphyromonas gingivalis is a major oral bacterial species implicated in the pathogenesis of periodontitis. Processing of interleukin (IL)‐1 family cytokines is regulated by an intracellular innate immune response system, known as the NALP3 [nacht domain‐, leucine‐rich repeat‐, and pyrin domain (PYD)‐containing protein 3] inflammasome complex. The aim of the present study was to investigate by quantitative real‐time polymerase chain reaction (PCR) the mRNA expression of NALP3, its effector molecule apoptosis associated speck‐like protein (ASC), its putative antagonist NLRP2 (NLR family, PYD‐containing protein 2), IL‐1β and IL‐18 (i) in gingival tissues from patients with gingivitis (n = 10), chronic periodontitis (n = 18), generalized aggressive periodontitis (n = 20), as well as in healthy subjects (n = 20), (ii) in vitro in a human monocytic cell line (Mono‐Mac‐6), in response to P. gingivalis challenge for 6 h. The clinical data indicate that NALP3 and NLRP2, but not ASC, are expressed at significantly higher levels in the three forms of inflammatory periodontal disease compared to health. Furthermore, a positive correlation was revealed between NALP3 and IL‐1β or IL‐18 expression levels in these tissues. The in vitro data demonstrate that P. gingivalis deregulates the NALP3 inflammasome complex in Mono‐Mac‐6 cells by enhancing NALP3 and down‐regulating NLRP2 and ASC expression. In conclusion, this study reveals a role for the NALP3 inflammasome complex in inflammatory periodontal disease, and provides a mechanistic insight to the host immune responses involved in the pathogenesis of the disease by demonstrating the modulation of this cytokine‐signalling pathway by bacterial challenge.     

Aggregatibacter actinomycetemcomitans infection causes DNA double‐strand breaks in host cells

Periodontal disease, an inflammatory disease, is caused by infection with periodontal pathogens. Long‐term periodontal disease increases the risk of oral carcinogenesis. Similar to other peptic cancers, oral carcinogenesis also requires multiple genome instabilities; however, the risk factors related to the accumulation of genome instabilities are poorly understood. Here, we suggested that specific periodontal pathogens may increase the risk of genome instability. Accordingly, we screened several periodontal pathogens based on the ability to induce DNA double‐strand breaks (DSBs) in host cells. We found that Aggregatibacter actinomycetemcomitans Y4 infection induced DSB formation in host cells. To assess whether DSB formation induced by infection with A. actinomycetemcomitans occurred through apoptotic chromosome fragmentation, cells were treated with a caspase inhibitor, Z‐VAD‐FMK. DSB accumulation induced by infection with A. actinomycetemcomitans was observed, even in the presence of Z‐VAD‐FMK, suggesting that this breakage occurred independently of apoptosis. These results suggested that some periodontal pathogens can increase the risk of genome instabilities in host cells and subsequently increase the risk of carcinogenesis.     

Severe chronic periodontitis is not common in Acromegaly: Potential protective role of gingival BMP-2

Background/aimAdvanced chronic periodontitis is observed rarely in acromegaly. Periodontal tissue including the alveolar bone is seemed to be spared from the systemic metabolic derangements of bone in this patient population. Chronic elevation of growth hormone, IGF-1, and bone morphogenetic proteins may play a role in periodontal tissue regeneration in acromegalics. In this study, we aimed to evaluate the potential roles of local gingival bone morphogenetic proteins (BMP) in periodontal tissue pathology in acromegaly.Materials and methodsThirty-five patients with acromegaly and 22 healthy subjects were recruited. All the participants were examined by the same periodontologist for the diagnosis of periodontal diseases. BMP-2 and -4 were studied in gingival crevicular fluid.ResultsGingival BMP-2 and BMP-4 levels were similar in acromegaly and control groups in general, with and without chronic periodontitis. For all the participants, gingival BMP-2 levels were statistically lower in those participants with chronic periodontitis then those without periodontitis (29.4 ± 11.2 vs. 41.2 ± 23.2, respectively, p = 0.027). Causal relation between the gingival BMP levels and periodontal tissue health status was tested with one way ANOVA which revealed a significant difference between gingival BMP-2 levels in those with different degrees of periodontal tissue pathology (p = 0.025). When analyzed separately, gingival BMP-2 levels revealed a causal relation with the degree of periodontal pathology with borderline significance only in patients with acromegaly (p = 0.057).ConclusionAcromegaly is a disease with an unexpectedly low frequency of advanced periodontitis, irrespective of the long disease duration and pathognomonic oral manifestations. BMP-2 might have a protective role against chronic advanced periodontitis in these patients.     

Candida albicans enhances invasion of human gingival epithelial cells and gingival fibroblasts by Porphyromonas gingivalis

Although Candida albicans has been isolated from periodontal pockets, its relationship to periodontitis is unclear. In this study, we investigated the effect of C. albicans on the adhesion and invasion of Ca9-22, a human gingival epithelial cell line, and human gingival fibroblasts by Porphyromonas gingivalis. Heat-killed C. albicans and water-soluble mannoprotein-β-glucan complex from C. albicans (CAWS) did not enhance P. gingivalis adhesion or upregulate the expression of β1 integrin and ICAM-1, which are required for P. gingivalis invasion; both the epithelial cells and fibroblasts expressed dectin-1, which recognizes components of the C. albicans cell wall. However, pretreatment of Ca9-22 cells and human gingival fibroblasts with heat-killed C. albicans or CAWS significantly enhanced P. gingivalis invasion. These results suggest that C. albicans may exacerbate infectious disease by enhancing the invasion of host cells by anaerobic bacteria.