A comparative study on periodontitis and periodontitis-associated bacteria in Somali and non-Somali children and adolescents living in Trollhättan, Sweden.

The reported prevalence of periodontitis in children and adolescents varies considerably between populations globally. This cross-sectional study compares clinical and microbiological findings on 83 Somali immigrants and 96 non-Somali children aged 10-17 years old living in Trollhättan, Sweden. The clinical examination included registration of bleeding on probing, plaque, and calculus on incisors and first molars. The distance between cemento-enamel junction and bone level was measured on bitewing radiographs. Pooled microbiological samples (1 µL) were taken from the mesial surface of 16, 11, 31, 36, and analyzed by culture and real-time polymerase chain reaction for seven periodontal associated bacterial species. The Somali participants had poorer oral hygiene and more bleeding, plaque, and calculus. Ten of the Somali but none of the non-Somali participants showed periodontal breakdown (radiographical bone loss > 3 mm), corresponding to a prevalence of 12% (95% CI: 5.9, 21.0%). The presence of A. actinomycetemcomitans was almost exclusively associated with Somali participants. Further, the JP2 clone was found in five Somalis (including two periodontitis cases) confirming the association of this clone with African populations. The Somali group showed significantly higher frequencies and numbers of Porphyromonas gingivalis and Treponema denticola, implying a mature and adult type of subgingival microbiota.

A rare CTSC mutation in Papillon-Lefèvre Syndrome results in abolished serine protease activity and reduced NET formation but otherwise normal neutrophil function.

Papillon-Lefèvre Syndrome (PLS) is an autosomal recessive monogenic disease caused by loss-of-function mutations in the CTSC gene, thus preventing the synthesis of the protease Cathepsin C (CTSC) in a proteolytically active form. CTSC is responsible for the activation of the pro-forms of the neutrophil serine proteases (NSPs; Elastase, Proteinase 3 and Cathepsin G), suggesting its involvement in a variety of neutrophil functions. In PLS neutrophils, the lack of CTSC protease activity leads to inactivity of the NSPs. Clinically, PLS is characterized by an early, typically pre-pubertal, onset of severe periodontal pathology and palmoplantar hyperkeratosis. However, PLS is not considered an immune deficiency as patients do not typically suffer from recurrent and severe (bacterial and fungal) infections. In this study we investigated an unusual CTSC mutation in two siblings with PLS, a 503A>G substitution in exon 4 of the CTSC gene, expected to result in an amino acid replacement from tyrosine to cysteine at position 168 of the CTSC protein. Both patients bearing this mutation presented with pronounced periodontal pathology. The characteristics and functions of neutrophils from patients homozygous for the 503A>G CTSC mutation were compared to another previously described PLS mutation (755A>T), and a small cohort of healthy volunteers. Neutrophil lysates from patients with the 503A>G substitution lacked CTSC protein and did not display any CTSC or NSP activity, yet neutrophil counts, morphology, priming, chemotaxis, radical production, and regulation of apoptosis were without any overt signs of alteration. However, NET formation upon PMA-stimulation was found to be severely depressed, but not abolished, in PLS neutrophils.

The neutrophil subset defined by CD177 expression is preferentially recruited to gingival crevicular fluid in periodontitis.

In recent years, the concept of distinct subpopulations of human neutrophils has attracted much attention. One bona fide subset marker, exclusively expressed by a proportion of circulating neutrophils in a given individual, and therefore dividing neutrophils in two distinct subpopulations, is the glycoprotein CD177. CD177 is expressed on the plasma and granule membranes of 0-100% of circulating neutrophils depending on the donor. Several in vitro studies have linked CD177 to neutrophil transmigration, yet very few have looked at the role of CD177 for tissue recruitment in vivo. We investigate whether the CD177+ and CD177- neutrophil subsets differ in their propensity to migrate to both aseptic- and microbe-triggered inflamed human tissues. Microbe-triggered neutrophil migration was evaluated in samples of gingival crevicular fluid (GCF) from patients with periodontitis, whereas neutrophil migration to aseptic inflammation was evaluated in synovial fluid from patients with inflammatory arthritis, as well as in exudate from experimental skin chambers applied on healthy donors. We found that the proportion of CD177+ neutrophils was significantly higher in GCF from patients with periodontitis, as compared to blood from the same individuals. Such accumulation of CD177+ neutrophils was not seen in the two models of aseptic inflammation. Moreover, the proportion of CD177+ neutrophils in circulation was significantly higher in the periodontitis patient group, as compared to healthy donors. Our data indicate that the CD177+ neutrophil subset is preferentially recruited to the gingival crevice of periodontitis patients, and may imply that this subtype is of particular importance for situations of microbe-driven inflammation.

Interleukin-17-producing T cells and interleukin-17 mRNA expression in periodontitis and long-standing gingivitis lesions.

BACKGROUND: T helper17 cells (Th17) are key targets in the evaluation of differences between "destructive" and "non-destructive" periodontal lesions. The aim of the present study was to analyze the density of interleukin-17 (IL-17) producing T cells and IL-17 mRNA expression in lesions representing severe periodontitis and longstanding gingivitis. METHODS: Two groups of patients were recruited. The gingivitis group consisted of 28 patients, 41-70 years old, with evident signs of gingival inflammation but no attachment loss. The periodontitis group consisted of 36 patients, 33-67 years of age. A gingival biopsy was obtained from one selected diseased site from each patient and prepared for immunohistochemical and reverse transcription, quantitative polymerase chain reaction (RT-qPCR) analysis. RESULTS: Although the density of CD3 positive cells (T cells) did not differ between the two types of lesions, the total number and density of cells positive for CD3+CD161 (IL-17-producing T-cells) were larger in periodontitis than in long-standing gingivitis lesions. About 30% of CD3-cells in periodontitis lesions were also positive for CD161. The corresponding figure for gingivitis samples was 15%. Analysis of covariance (ANCOVA) analysis revealed that differences between periodontitis and gingivitis samples remained after adjusting for smoking, age, and gender. In addition, males had larger proportions of IL-17 producing T cells than females in both groups. The IL-17 mRNA expression was higher in periodontitis than in gingivitis samples. CONCLUSION: It is suggested that IL-17 producing T cells represent a significant feature in the detection of differences between destructive and non-destructive lesions.

Age of onset of disease in subjects with severe periodontitis: A 9- to 34-year retrospective study.

AIM: The aim was to retrospectively assess the age of onset of disease in a group of patients, 30-45 years of age, diagnosed with severe, generalised periodontitis. MATERIAL & METHODS: Seventy-four patients agreed to be part of the study. Patient files and radiographs of 42 patients were retrieved from >80 private and public dental clinics. Interproximal sites in radiographs presenting with identifiable cement-enamel junction (CEJ) and alveolar bone crest (BC) were analysed. The distance between CEJ and BC was measured, and two thresholds were used; ≥3 mm and ≥5 mm. The lowest patient age at which a radiographic examination revealed a CEJ-BC distance of ≥3 mm (F3) and ≥5 mm (F5) at any site was recorded. Similarly, the highest patient age at which a radiographic examination revealed absence of sites with CEJ-BC ≥3 mm (L0) was assessed. RESULTS: Complete sets of radiographs including periods prior to periodontal breakdown (L0) and disease stages F3, F5 and at recruitment were retrieved in 19 patients. Onset of disease, that is, the interval between L0 and F3, occurred on the average between 22.3 and 28.1 years of age and sites exhibiting severe bone loss (F5) were detected at the age of about 32.4 years. CONCLUSION: Severe, generalised periodontitis in 30- to 45-year-old subjects of the current sample commenced mainly between 22 and 28 years of age.

Expression of TET2 enzyme indicates enhanced epigenetic modification of cells in periodontitis.

DNA methylation is an important epigenetic mechanism involved in the regulation of gene expression, and a reduction in DNA methylation influences cell-cycle progression and cell differentiation in inflammatory cells. The aim of the present study was to analyze the DNA-methylation pattern at local and global/systemic levels in patients with periodontitis and gingivitis. Twenty-one subjects with generalized, severe periodontitis and 17 subjects with gingival inflammation but no attachment loss were recruited. Gingival biopsies and peripheral blood samples were collected and prepared for immunohistochemical analysis of 5-methylcytosine (5mC), 5-hydroxymethylcytosine (5hmC), ten-eleven translocation 2 (TET2), and DNA methyltransferase 1 (DNMT1). Whilst a similar pattern for 5mC and 5hmC DNA methylation was found in both types of lesions, a significantly larger proportion of TET2-positive cells was found in periodontitis lesions than in gingivitis lesions. Quantitative real-time PCR analysis showed no differences between gingivitis and periodontitis lesions regarding expression of TET2 and isocitrate dehydrogenase (IDH) genes, while the global level of 5hmC was significantly higher in blood than in tissue in patients with periodontitis. It is suggested that epigenetic changes are more common in periodontitis lesions than in gingivitis lesions and that such changes are tissue specific.

Influence of epigenetic modifications of the interleukin-10 promoter on IL10 gene expression.

Epigenetic modifications of DNA and its associated proteins influence gene expression. The -1087 interleukin-10 (IL10) gene polymorphism is associated with differences in IL10 expression. The objectives of this study were to analyze the effect of DNA methylation and histone modifications on IL10 gene expression, the differences in epigenetic modifications between GG and AA genotypes of the -1087 IL10 gene polymorphism, and the methylation pattern in the region close to the -1087 position. Using B cells obtained from subjects with GG and AA genotypes we demonstrated that treatment with histone deacetylase inhibitors and 5-aza-2-deoxycytidine resulted in an increase in the production of IL10 mRNA. The chromatin immunoprecipitation assay revealed that stimulation with lipopolysaccharide resulted in a higher fold increase in the acetylation of histone H4 and in the methylation of histone H3 for GG genotype cells than for AA genotype cells. The increase in acetylation of histone H3 was larger for AA genotype cells than for GG genotype cells. For unstimulated cells the acetylation and methylation of histone H3 were higher for GG genotype cells than for AA genotype cells, while AA genotype cells had a higher increase in acetylation of histone H4. DNA methylation assays revealed that the three CpG sites distal to the -1087 site were methylated in blood cells and gingival tissues.

Interleukin-10 genotypes of the -1087 single nucleotide polymorphism influence sp1 expression in periodontitis lesions.

BACKGROUND: Interleukin (IL)-10 is an important cytokine in immune regulation, and the -1087 IL-10 single nucleotide polymorphism (SNP) is associated with chronic periodontitis. The binding of the transcription factor Sp1 to the -1087 position in the IL-10 promoter upregulates IL-10 gene expression, especially in patients with the GG genotype. A correlation between the -1087 GG genotype and high IL-10 and Sp1 gene expressions was found. METHODS: Twenty-five individuals with severe generalized chronic periodontitis were genotyped for the -1087 IL-10 gene polymorphism. SV40 promoter factor 1/specificity protein 1 (Sp1) and IL-10 mRNA were analyzed using a real-time polymerase chain reaction. The amount of Sp1-positive cells and Sp1-positive B cells, as well as the amount of Sp1 protein, in periodontitis lesions were assessed using immunohistochemistry and an in situ proximity ligation assay. RESULTS: The mRNA expression of Sp1 and IL-10 in patients with the GG genotype was four times higher than that in patients with the AA genotype. Proportions of Sp1-positive cells overall and Sp1-positive B cells were larger in patients with the GG genotype than in patients with the AA genotype. CONCLUSION: The transcription factor Sp1 was present in large amounts in periodontitis lesions, and the local expression of Sp1 was related to the -1087 IL-10 SNP.