Transferrin receptor 2 mitigates periodontitis-driven alveolar bone loss.

Periodontitis is associated with significant alveolar bone loss. Patients with iron overload suffer more frequently from periodontitis, however, the underlying mechanisms remain largely elusive. Here, we investigated the role of transferrin receptor 2 (Tfr2), one of the main regulators of iron homeostasis, in the pathogenesis of periodontitis and the dental phenotype under basal conditions in mice. As Tfr2 suppresses osteoclastogenesis, we hypothesized that deficiency of Tfr2 may exacerbate periodontitis-induced bone loss. Mice lacking Tfr2 (Tfr2-/- ) and wild-type (Tfr2+/+ ) littermates were challenged with experimental periodontitis. Mandibles and maxillae were collected for microcomputed tomography and histology analyses. Osteoclast cultures from Tfr2+/+ and Tfr2-/- mice were established and analyzed for differentiation efficiency, by performing messenger RNA expression and protein signaling pathways. After 8 days, Tfr2-deficient mice revealed a more severe course of periodontitis paralleled by higher immune cell infiltration and a higher histological inflammation index than Tfr2+/+ mice. Moreover, Tfr2-deficient mice lost more alveolar bone compared to Tfr2+/+ littermates, an effect that was only partially iron-dependent. Histological analysis revealed a higher number of osteoclasts in the alveolar bone of Tfr2-deficient mice. In line, Tfr2-deficient osteoclastic differentiation ex vivo was faster and more efficient as reflected by a higher number of osteoclasts, a higher expression of osteoclast markers, and an increased resorptive activity. Mechanistically, Tfr2-deficient osteoclasts showed a higher p38-MAPK signaling and inhibition of p38-MAPK signaling in Tfr2-deficient cells reverted osteoclast formation to Tfr2+/+ levels. Taken together, our data indicate that Tfr2 modulates the inflammatory response in periodontitis thereby mitigating effects on alveolar bone loss.

Psychopathologies and socioeconomic status as risk indicators for periodontitis: a survey-based investigation in German dental practices.

OBJECTIVES: Periodontitis is a highly prevalent multifactorial disease associated with various mental disorders. However, study results about this association are still contradictory. One methodological reason could be the neglect of potential confounders, such as socioeconomic factors or mental comorbidity. Our study examined a wide range of potential psychosocial risk indicators to identify those with relevant associations to periodontitis. MATERIALS AND METHODS: In a cross-sectional study, 111 patients with periodontitis (PERIO) (> 30% teeth with approximal attachment loss ≥ 5 mm) and 110 patients without periodontitis (NON-PERIO) were recruited in four dental practices in Germany. Clinical attachment loss, pocket depth, plaque, bleeding on probing, and DMFT were measured. Psychopathologic symptoms and socioeconomic status were recorded using self-report questionnaires (DAS, PHQ-8, GAD-7, CTS, SCOFF, AUDIT, FTND, SSS-8, SES). RESULTS: The PERIO group reported significantly lower socioeconomic status (Cohen's d = 0.49) and higher psychopathological symptom burden than the NON-PERIO regarding dental anxiety (d = 0.86) and avoidance behavior, nicotine dependency (d = 0.84), depressiveness (d = 0.46), general anxiety (d = 0.45), somatic symptoms (d = 0.42), and childhood traumatization (d = 0.34). No significant group differences existed for alcohol abuse and eating disorders. Dental anxiety was the strongest predictor of periodontitis and showed significant correlations with other psychopathologies and social status. CONCLUSIONS: Out of all psychosocial factors, socioeconomic status and dental anxiety showed the greatest association with periodontitis. CLINICAL RELEVANCE: Dentists should encourage socially disadvantaged and dentally anxious patients in the utilization of prevention and dental care. Furthermore, physicians and psychotherapists can contribute to the early detection of dental anxiety, oral diseases, and avoidance behavior.

Massive data analyses show negative impact of type 1 and 2 diabetes on the outcome of periodontal treatment.

OBJECTIVES: The aim was to evaluate the impact of diabetes on the outcome of periodontal treatment based on massive data analyses. MATERIALS AND METHODS: Data originated from the database of a major German National Health Insurance. Patients who underwent periodontal treatment were allocated to four groups according to their medical condition: type 1 diabetes (D1), type 2 diabetes with the intake of oral anti-diabetics (D2M), type 2 diabetes without the intake of oral anti-diabetics (D2), and a control group without diabetes (ND). Four-year Kaplan-Meier survival analyses on the patient level and multivariate regression analyses were conducted for tooth extraction. RESULTS: Of 415,718 patients, 4139 matched the criteria for D1, 22,430 for D2M, and 23,576 for D2. At 4 years, the cumulative survival rate (no extraction) was 51.7% in the D1 group, 54.0% in the D2M group, and 57.7% in the D2 group. The ND control group had a significantly higher survival rate of 65.9% (P < 0.0001). In the multivariate analyses, both diabetes types were significantly associated with further tooth loss after periodontal treatment. CONCLUSIONS: The diagnosis of diabetes type 1 or 2 seems to be associated with a higher risk of tooth loss after periodontal treatment. CLINICAL RELEVANCE: The long-term prognosis of teeth in diabetes patients should be judged carefully.

Impact of 0.1% octenidine mouthwash on plaque re-growth in healthy adults: a multi-center phase 3 randomized clinical trial.

OBJECTIVES: To investigate plaque inhibition of 0.1% octenidine mouthwash (OCT) vs. placebo over 5 days in the absence of mechanical plaque control. MATERIALS AND METHODS: For this randomized, placebo-controlled, double-blind, parallel group, multi-center phase 3 study, 201 healthy adults were recruited. After baseline recording of plaque index (PI) and gingival index (GI), collection of salivary samples, and dental prophylaxis, subjects were randomly assigned to OCT or placebo mouthwash in a 3:1 ratio. Rinsing was performed twice daily for 30 s. Colony forming units in saliva were determined before and after the first rinse. At day 5, PI, GI, and tooth discoloration index (DI) were assessed. Non-parametric van Elteren tests were applied with a significance level of p < 0.05. RESULTS: Treatment with OCT inhibited plaque formation more than treatment with placebo (PI: 0.36 vs. 1.29; p < 0.0001). OCT reduced GI (0.04 vs. placebo 0.00; p = 0.003) and salivary bacterial counts (2.73 vs. placebo 0.24 lgCFU/ml; p < 0.0001). Tooth discoloration was slightly higher under OCT (DI: 0.25 vs. placebo 0.00; p = 0.0011). Mild tongue staining and dysgeusia occurred. CONCLUSIONS: OCT 0.1% mouthwash inhibits plaque formation over 5 days. It therefore can be recommended when regular oral hygiene is temporarily compromised. CLINICAL RELEVANCE: When individual plaque control is compromised, rinsing with octenidine mouthwash is recommended to maintain healthy oral conditions while side effects are limited.

A genome-wide association study identifies nucleotide variants at SIGLEC5 and DEFA1A3 as risk loci for periodontitis.

Periodontitis is one of the most common inflammatory diseases, with a prevalence of 11% worldwide for the severe forms and an estimated heritability of 50%. The disease is characterized by destruction of the alveolar bone due to an aberrant host inflammatory response to a dysbiotic oral microbiome. Previous genome-wide association studies (GWAS) have reported several suggestive susceptibility loci. Here, we conducted a GWAS using a German and Dutch case-control sample of aggressive periodontitis (AgP, 896 cases, 7,104 controls), a rare but highly severe and early-onset form of periodontitis, validated the associations in a German sample of severe forms of the more moderate phenotype chronic periodontitis (CP) (993 cases, 1,419 controls). Positive findings were replicated in a Turkish sample of AgP (223 cases, 564 controls). A locus at SIGLEC5 (sialic acid binding Ig-like lectin 5) and a chromosomal region downstream of the DEFA1A3 locus (defensin alpha 1-3) showed association with both disease phenotypes and were associated with periodontitis at a genome-wide significance level in the pooled samples, with P = 1.09E-08 (rs4284742,-G; OR = 1.34, 95% CI = 1.21-1.48) and P = 5.48E-10 (rs2738058,-T; OR = 1.28, 95% CI = 1.18-1.38), respectively. SIGLEC5 is expressed in various myeloid immune cells and classified as an inhibitory receptor with the potential to mediate tyrosine phosphatases SHP-1/-2 dependent signaling. Alpha defensins are antimicrobial peptides with expression in neutrophils and mucosal surfaces and a role in phagocyte-mediated host defense. This study identifies the first shared genetic risk loci of AgP and CP with genome-wide significance and highlights the role of innate and adaptive immunity in the etiology of periodontitis.

Effect of toothpaste containing amine fluoride and stannous chloride on the reduction of dental plaque and gingival inflammation. A randomized controlled 12-week home-use study.

OBJECTIVES: This single-centre, controlled, randomized, double-blinded clinical study in parallel groups was performed to assess the efficacy of an experimental toothpaste on plaque and gingivitis. METHODS: In adult subjects with gingivitis, amine fluoride/stannous chloride toothpaste (test) and monofluorophosphate toothpaste (control) were applied twice daily by regular toothbrushing at home. Evaluations of plaque index (PI), gingival index (GI), modified sulcus bleeding index (mSBI) and safety took place at baseline and after 3 and 12 weeks of study product use. After study completion, all subjects received a dental prophylaxis. A descriptive statistical analysis included means and standard deviations. Unpaired t tests compared index reductions between groups at a significance level of 0.05. RESULTS: Intention-to-treat analysis included 240 out of 241 subjects. Baseline mean PI was reduced by 0.87 ± 0.35 in the test group and by 0.65 ± 0.41 in the control group. Within-group differences and between-group differences in index reduction were statistically significant (P < 0.001). Mean GI and mSBI were reduced significantly over time (P < 0.001) with no clinically meaningful differences between groups. CONCLUSIONS: Both toothpastes reduced plaque and gingivitis statistically significant and clinically meaningful over 12 weeks. Compared to the control toothpaste, application of the amine fluoride/stannous chloride toothpaste led to a clinically meaningful and more pronounced plaque reduction.

Impact of different concentrations of an octenidine dihydrochloride mouthwash on salivary bacterial counts: a randomized, placebo-controlled cross-over trial.

OBJECTIVES: This bi-centric, placebo-controlled, randomized, evaluator-blinded, incomplete cross-over clinical phase II trial was initialized to identify the most appropriate concentration of octenidine dihydrochloride (OCT) in mouth rinses. MATERIALS AND METHODS: Rinses of 0.10, 0.15, and 0.20% OCT were compared to a saline placebo rinse regarding the reduction of salivary bacterial counts (SBCs) in 90 gingivitis patients over 4 days. Changes in plaque (PI) and gingival index (GI), taste perception, and safety issues were evaluated. RESULTS: At baseline, the first OCT (0.10, 0.15, 0.20%) rinse resulted in a decrease of SBC (reduction by 3.63-5.44 log10 colony forming units [CFU]) compared to placebo (p < 0.001). Differences between OCT concentrations were not verified. After 4 days, the last OCT rinse again resulted in a significant SBC decrease (3.69-4.22 log10 CFU) compared to placebo (p < 0.001). Overall, SBC reduction between baseline and day 4 was significantly higher in OCT 0.15 and 0.20% groups compared to OCT 0.10% and placebo. Mean GI/PIs were significantly lower in OCT groups than in the placebo group (p < 0.001). Differences in GI/PI between OCT groups were not verified. Adverse effects increased with increasing OCT concentrations. CONCLUSIONS: Considering antibacterial efficacy, frequency of adverse events, and user acceptance, 0.10% OCT was identified as the preferred concentration to be used in future clinical trials. CLINICAL RELEVANCE: Due to its low toxicity and pronounced antibacterial properties, octenidine dihydrochloride (OCT) is a promising candidate for the use in antiseptic mouth rinses. OCT concentrations of 0.10% are recommended for future clinical trials evaluating the plaque-reducing properties of OCT mouth rinses. ( www.clinicaltrials.gov , NCT022138552).

Tooth staining potential of experimental amine fluoride/stannous fluoride mouth rinse formulations-a randomized crossover forced staining study.

OBJECTIVES: It was the aim to investigate experimental mouth rinses concerning their tooth and tongue staining potential using the standardized short-term forced staining model. MATERIALS AND METHODS: A single centre, clinically controlled, randomized, investigator-blinded study was conducted in a crossover design. In healthy dental students, three experimental AmF/SnF2 (A, B, C) mouth rinses and a phenolic/essential oil rinse (D) were compared to a water control (E). Four treatment days consisted of eight hourly rinses with mouth rinse and black tea. Mechanical oral hygiene was ceased. At the fifth day, tooth and tongue staining indices were recorded. Between treatment periods, a 10-day washout phase was performed. RESULTS: Twenty-eight participants entered and completed the study. All mouth rinses including the water control led to tooth and tongue staining. Most tooth staining occurred after rinsing with test rinse A, followed by B, D, C and E. Statistically significant differences existed between products A and C, D, and E. Most tongue staining happened in group B, followed by A, D, C and E (not statistically significant). CONCLUSION: Within the limitations of the model, mouth rinse C has a promising potential of causing less tooth discoloration than other AmF/SnF2 rinses. C is highly recommended to be investigated in further long-term clinical studies on its in vivo staining potential and antiplaque efficacy. CLINICAL RELEVANCE: This forced staining study has proven that one of the experimental AmF/SnF2 rinses leads to less staining than the other experimental AmF/SnF2 rinses. These experimental results have to be confirmed by further clinical investigations.

A large candidate-gene association study suggests genetic variants at IRF5 and PRDM1 to be associated with aggressive periodontitis.

AIM: Epidemiological and clinical studies indicated a relationship of periodontitis with rheumatoid arthritis (RA). We aimed to identify shared genetic susceptibility loci of RA and periodontitis. MATERIALS AND METHODS: Forty-seven risk genes of genome-wide significance of RA and SLE were genotyped in a German case-control sample of aggressive periodontitis (AgP), using Immunochip genotyping arrays (Illumina, 600 cases, 1440 controls) and Affymetrix 500 K Genotyping Arrays (280 cases and 983 controls). Significant associations were replicated in 168 Dutch AgP cases and 679 controls and adjusted for the confounders smoking and sex. RESULTS: Variants at IRF5 and PRDM1 showed association with AgP. Upon covariate adjustment for smoking and sex, the most strongly associated variant at IRF5 was the rare variant rs62481981 (ppooled  = 0.0012, odds ratio [OR] = 3.1, 95% confidence interval [95% CI] = 1.6-6.1; 801 cases, 1476 controls).Within PRDM1 it was rs6923419 (ppooled  = 0.004, OR = 0.7, 95% CI = 0.6-0.9; 833 cases, 1440 controls). The associations lost significance after correction for multiple testing in the replication. Both genes are implicated in beta-interferon signalling and are also genome-wide associated with SLE and inflammatory bowel disease. CONCLUSION: The study gives no definite evidence for a pathogenic genetic link of periodontitis and RA but suggests IRF5 and PRDM1 as shared susceptibility factors.

Genome-wide exploration identifies sex-specific genetic effects of alleles upstream NPY to increase the risk of severe periodontitis in men.

AIM: Periodontitis (PD) is influenced by genetic as well as lifestyle and socio-economic factors. Epidemiological studies show that men are at greater risk of severe forms of PD, suggesting interplay between sex and genetic factors. We aimed to systematically analyse patients with aggressive periodontitis (AgP) for gene-sex interactions. MATERIALS AND METHODS: Three hundred and twenty-nine German AgP cases and 983 controls were genotyped with Affymetrix 500K Arrays and were analysed by logistic regression analysis. The most significant gene-sex interaction was replicated in an independent sample of 382 German/Austrian AgP cases and 489 controls. RESULTS: Ten single-nucleotide polymorphisms (SNPs) in strong linkage disequilibrium (r(2)  > 0.85) upstream the gene neuropeptide Y (NPY) suggested gene-sex interaction (p < 5 × 10(-5) ). SNP rs198712 showed the strongest association in interaction with sex (p = 5.4 × 10(-6) ) with odds ratios in males and females of 1.63 and 0.69 respectively. In the replication, interaction of sex with rs198712 was verified with p = 0.022 (pooled p = 4.03 × 10(-6) ) and similar genetic effects. Analysis of chromatin elements from ENCODE data revealed tissue-specific transcription at the associated non-coding region. CONCLUSION: This study is the first to observe a sexually dimorphic role of alleles at NPY in humans and support previous genome-wide findings of a role of NPY in severe PD.

SLC23A1 polymorphism rs6596473 in the vitamin C transporter SVCT1 is associated with aggressive periodontitis.

AIM: Identification of variants within genes SLC23A1 and SLC23A2 coding for vitamin C transporter proteins associated with aggressive (AgP) and chronic periodontitis (CP). MATERIAL AND METHODS: Employment of three independent case-control samples of AgP (I. 283 cases, 979 controls; II. 417 cases, 1912 controls; III. 164 cases, 357 controls) and one sample of CP (1359 cases, 1296 controls). RESULTS: Stage 1: Among the tested single-nucleotide polymorphisms (SNPs), the rare allele (RA) of rs6596473 in SLC23A1 showed nominal significant association with AgP (p = 0.026, odds ratio [OR] 1.26, and a highly similar minor allele frequency between different control panels. Stage 2: rs6596473 showed no significant association with AgP in the replication with the German and Dutch case-control samples. After pooling the German AgP populations (674 cases, 2891 controls) to significantly increase the statistical power (SP = 0.81), rs6596473 RA showed significant association with AgP prior to and upon adjustment with the covariates smoking and gender with padj  = 0.005, OR = 1.35. Stage 3: RA of rs6596473 showed no significant association with severe CP. CONCLUSION: SNP rs6596473 of SLC23A1 is suggested to be associated with AgP. These results add to previous reports that vitamin C plays a role in the pathogenesis of periodontitis.

Validation of reported genetic risk factors for periodontitis in a large-scale replication study.

AIM: Many studies investigated the role of genetic variants in periodontitis, but few were established as risk factors. We aimed to validate the associations of recent candidate genes in aggressive periodontitis (AgP). MATERIAL AND METHODS: We analysed 23 genes in 600 German AgP patients and 1441 controls on the Illumina custom genotyping array Immunochip. We tested a suggestive association in a Dutch and German/Austrian AgP case-control sample, and a German chronic periodontitis (CP) case-control sample using Sequenom iPlex assays. We additionally tested the common known risk variant rs1333048 of the gene ANRIL for its association in a Turkish and Italian population. RESULTS: None of the analysed genes gave statistical evidence for association. Upon covariate adjustment for smoking and gender, in the pooled German-Austrian AgP sample, IL10 SNP rs6667202 was associated with p = 0.016, OR = 0.77 (95% CI = 0.6-0.95), and in the Dutch AgP sample, adjacent IL10 SNP rs61815643 was associated with p = 0.0009, OR = 2.31 (95% CI = 1.4-3.8). At rs61815643, binding of the transcription factor PPARG was predicted. ANRIL rs1333048 was associated in the Turkish sample (pallelic = 0.026, OR = 1.67 [95% CI = 1.11-2.60]). CONCLUSIONS: Previous candidate genes carry no susceptibility factors for AgP. Association of IL-10 rs61815643 with AgP is suggested. ANRIL is associated with periodontitis across different populations.

A genome-wide association study identifies GLT6D1 as a susceptibility locus for periodontitis.

Periodontitis is a widespread, complex inflammatory disease of the mouth, which results in a loss of gingival tissue and alveolar bone, with aggressive periodontitis (AgP) as its most severe form. To identify genetic risk factors for periodontitis, we conducted a genome-wide association study in German AgP patients. We found AgP to be strongly associated with the intronic SNP rs1537415, which is located in the glycosyltransferase gene GLT6D1. We replicated the association in a panel of Dutch generalized and localized AgP patients. In the combined analysis including 1758 subjects, rs1537415 reached a genome-wide significance level of P= 5.51 x 10(-9), OR = 1.59 (95% CI 1.36-1.86). The associated rare G allele of rs1537415 showed an enrichment of 10% in periodontitis cases (48.4% in comparison with 38.8% in controls). Fine-mapping and a haplotype analysis indicated that rs1537415 showed the strongest association signal. Sequencing identified no further associated variant. Tissue-specific expression analysis of GLT6D1 indicated high transcript levels in the leukocytes, the gingiva and testis. Analysis of potential transcription factor binding sites at this locus predicted a significant reduction of GATA-3 binding affinity, and an electrophoretic mobility assay indicated a T cell specific reduction of protein binding for the G allele. Overexpression of GATA-3 in HEK293 cells resulted in allele-specific binding of GATA-3, indicating the identity of GATA-3 as the binding protein. The identified association of GLT6D1 with AgP implicates this locus as an important susceptibility factor, and GATA-3 as a potential signaling component in the pathophysiology of periodontitis.

Common genetic risk variants of TLR2 are not associated with periodontitis in large European case-control populations.

AIM: Involvement of TLR2 in the pathophysiology of periodontitis has widely been discussed, but hitherto, no validated genetic associations were reported. Previous association studies lacked sufficient statistical power and adequate haplotype information to draw unambiguous conclusions. The aim of this study was to comprehensively investigate TLR2 linkage disequilibrium (LD) regions for their potential associations with periodontitis in two large analysis populations of aggressive (AgP) and chronic periodontitis (CP) of North West European descent. MATERIALS AND METHODS: The study population comprised 598 AgP patients, 914 CP patients and 1804 healthy controls. Analysis of TLR2 LD regions was performed with haplotype tagging SNPs (tagSNPs) using SNPlex and TaqMan genotyping assays. Genotypic, dominant, multiplicative, and recessive genetic models were tested. The genotypes were adjusted for the covariates smoking, diabetes, and gender. Resequencing was performed by Sanger technology. RESULTS: Upon covariate adjustment and correction for multiple testing, no tagSNPs showed significant associations with AgP or CP. Targeted resequencing of exon 3 in 47 AgP cases identified carriership of two common and three rare variants. CONCLUSION: Common LD regions of TLR2 do not show genetic associations with periodontitis in the North West European population. Resequencing of exon 3 could not identify disease-associated rare variants in TLR2.

CDKN2BAS is associated with periodontitis in different European populations and is activated by bacterial infection.

Epidemiological studies have indicated a relationship between coronary heart disease (CHD) and periodontitis. Recently, CDKN2BAS was reported as a shared genetic risk factor of CHD and aggressive periodontitis (AgP), but the causative variant has remained unknown. To identify and validate risk variants in different European populations, we first explored 150 kb of the genetic region of CDKN2BAS including the adjacent genes CDKN2A and CDKN2B, covering 51 tagging single nucleotide polymorphisms (tagSNPs) in AgP and chronic periodontitis (CP) in individuals of Dutch origin (n=313). In a second step, we tested the significant SNP associations in an independent AgP and CP population of German origin (n=1264). For the tagSNPs rs1360590, rs3217992, and rs518394, we could validate the associations with AgP before and after adjustment for the covariates smoking, gender and diabetes, with SNP rs3217992 being the most significant (OR 1.48, 95% CI 1.19 to 1.85; p=0.0004). We further showed in vivo gene expression of CDKN2BAS, CDKN2A, CDKN2B, and CDK4 in healthy and inflamed gingival epithelium (GE) and connective tissue (CT), and detected a significantly higher expression of CDKN2BAS in healthy CT compared to GE (p=0.004). After 24 h of stimulation with Porphyromonas gingivalis in Streptococcus gordonii pre-treated gingival fibroblast (HGF) and cultured gingival epithelial cells (GECs), we observed a 25-fold and fourfold increase of CDKN2BAS gene expression in HGFs (p=0.003) and GECs (p=0.004), respectively. Considering the global importance of CDKN2BAS in the disease risk of CHD, this observation supports the theory of inflammatory components in the disease physiology of CHD.

Identification of a shared genetic susceptibility locus for coronary heart disease and periodontitis.

Recent studies indicate a mutual epidemiological relationship between coronary heart disease (CHD) and periodontitis. Both diseases are associated with similar risk factors and are characterized by a chronic inflammatory process. In a candidate-gene association study, we identify an association of a genetic susceptibility locus shared by both diseases. We confirm the known association of two neighboring linkage disequilibrium regions on human chromosome 9p21.3 with CHD and show the additional strong association of these loci with the risk of aggressive periodontitis. For the lead SNP of the main associated linkage disequilibrium region, rs1333048, the odds ratio of the autosomal-recessive mode of inheritance is 1.99 (95% confidence interval 1.33-2.94; P = 6.9 x 10(-4)) for generalized aggressive periodontitis, and 1.72 (1.06-2.76; P = 2.6 x 10(-2)) for localized aggressive periodontitis. The two associated linkage disequilibrium regions map to the sequence of the large antisense noncoding RNA ANRIL, which partly overlaps regulatory and coding sequences of CDKN2A/CDKN2B. A closely located diabetes-associated variant was independent of the CHD and periodontitis risk haplotypes. Our study demonstrates that CHD and periodontitis are genetically related by at least one susceptibility locus, which is possibly involved in ANRIL activity and independent of diabetes associated risk variants within this region. Elucidation of the interplay of ANRIL transcript variants and their involvement in increased susceptibility to the interactive diseases CHD and periodontitis promises new insight into the underlying shared pathogenic mechanisms of these complex common diseases.

Cytokine production by leukocytes of Papillon-Lefèvre syndrome patients in whole blood cultures.

Papillon-Lefèvre syndrome (PLS) is characterised by aggressively progressive periodontitis combined with palmo-plantar hyperkeratosis. It is caused by "loss of function" mutations in the cathepsin C gene. The hypothesis behind this study is that PLS patients' polymorphonuclear leukocytes (PMNs) produce more proinflammatory cytokines to compensate for their reduced capacity to neutralize leukotoxin and to eliminate Aggregatibacter actinomycetemcomitans. Production of more interleukin (IL)-8 would result in the attraction of more PMNs. The aim of this study was to evaluate the cytokine profile in PLS patients' blood cultures. Blood was sampled from eight PLS patients (one female) from six families (antiinfective therapy completed: six; edentulous: two) with confirmed cathepsin C mutations and deficient enzyme activity. Nine healthy males served as controls. Whole blood cultures were stimulated with highly pure lipopolysaccharide (LPS) from Escherichia coli R515 and IL-1ß plus tumor necrosis factor (TNF)-α. Thereafter, release of IL-1ß (stimulation: LPS and LPS plus adenosine triphosphate), IL-6, IL-8, interferon-inducible protein (IP)-10, and interferon (IFN)-γ (stimulation: LPS, IL-1ß/TNFα) were detected by ELISA. Medians of cytokine release were, with the exception of IP-10, slightly higher for PLS than for controls' cultures. None of these differences reached statistical significance. Increased production of IL-1ß, IL-6, IL-8, IP-10, or IFNγ as a significant means to compensate for diminished activity and stability of polymorphonuclear leukocyte-derived proteases could not be confirmed in this study. Cytokine profiles in blood cultures may not be used to identify PLS patients.

Replication of the association of chromosomal region 9p21.3 with generalized aggressive periodontitis (gAgP) using an independent case-control cohort.

BACKGROUND: The human chromosomal region 9p21.3 has been shown to be strongly associated with Coronary Heart Disease (CHD) in several Genome-wide Association Studies (GWAS). Recently, this region has also been shown to be associated with Aggressive Periodontitis (AgP), strengthening the hypothesis that the established epidemiological association between periodontitis and CHD is caused by a shared genetic background, in addition to common environmental and behavioural risk factors. However, the size of the analyzed cohorts in this primary analysis was small compared to other association studies on complex diseases. Using our own AgP cohort, we attempted to confirm the described associations for the chromosomal region 9p21.3. METHODS: We analyzed our cohort consisting of patients suffering from the most severe form of AgP, generalized AgP (gAgP) (n = 130) and appropriate periodontally healthy control individuals (n = 339) by genotyping four tagging SNPs (rs2891168, rs1333042, rs1333048 and rs496892), located in the chromosomal region 9p21.3, that have been associated with AgP. RESULTS: The results confirmed significant associations between three of the four SNPs and gAgP. The combination of our results with those from the study which described this association for the first time in a meta-analysis of the four tagging SNPs produced clearly lower p-values compared with the results of each individual study. According to these results, the most plausible genetic model for the association of all four tested SNPs with gAgP seems to be the multiplicative one. CONCLUSION: We positively replicated the finding of an association between the chromosomal region 9p21.3 and gAgP. This result strengthens support for the hypothesis that shared susceptibility genes within this chromosomal locus might be involved in the pathogenesis of both CHD and gAgP.

TLR4 and IL-18 gene variants in chronic periodontitis: impact on disease susceptibility and severity.

The aim of the study was to assess whether genotypes in the Toll-like receptor 4 gene and in the promoter of the interleukin-18 gene are associated with the susceptibility to chronic periodontitis. 108 chronic periodontitis patients and 76 controls were genotyped for c.896A>G/1196C>T (TLR4 gene) and for c.-368G>C/ c.-838C>A (IL-18 promoter). There were no significant differences in genotype and allele distributions between the study groups. Periodontitis severity in patients with TLR4 c.896AG/1196CT genotype was significantly higher than wildtype carriers. The percentage of teeth with clinical attachment loss > or = 5 mm was 77.3% and 58.8%, respectively (p < or = 0.006, t-test). All subjects were further classified into carriers and non-carriers of at least one variant of each gene. A logistic regression analysis adjusted for gender, smoking, and age showed no association between gene variant carrier status and periodontitis (OR = 1.98, 95% CI 0.61-6.39). The results did not show that IL-18 and TLR4 variants have an effect on the susceptibility to chronic periodontitis. Considering the low number of periodontitis patients carrying TLR4 variants (11%), a comparison of the periodontitis severity depending on the genotype has to be interpreted cautiously.