Aino Salminen

Salivary biomarkers of bacterial burden, inflammatory response, and tissue destruction in periodontitis

AIM Chronic periodontitis has an episodic and multifactorial character, with fluctuations in bacterial burden, inflammatory response, and tissue destruction. We investigated the association of selected salivary biomarkers with periodontal parameters and validated the use of a novel salivary diagnostic approach, the cumulative risk score (CRS), in detection of periodontitis in subjects with angiographically verified coronary artery disease diagnosis. MATERIALS AND METHODS The concentrations of matrix metalloproteinase (MMP)-8, interleukin (IL)-1β, and Porphyromonas gingivalis were analysed from saliva of 493 subjects. The subjects participated in a detailed clinical and radiographic oral examination. The CRS index, combining the three salivary biomarkers, was calculated for each subject. RESULTS High salivary concentrations of MMP-8, IL-1β, and P. gingivalis were associated with deepened periodontal pockets and alveolar bone loss, and MMP-8 and IL-1β with bleeding on probing. The CRS index had a stronger association with moderate to severe periodontitis (OR 6.13; 95% CI 3.11-12.09) than any of the markers alone. CONCLUSIONS Salivary concentrations of MMP-8, IL-1β, and P. gingivalis are associated with various clinical and radiographic measures of periodontitis. The CRS index, combining the three salivary biomarkers, is associated with periodontitis more strongly than any of the markers alone regardless of the coronary artery disease status of the patients.

Matrix metalloproteinase 8 degrades apolipoprotein A-I and reduces its cholesterol efflux capacity

Various cell types in atherosclerotic lesions express matrix metalloproteinase (MMP)‐8. We investigated whether MMP‐8 affects the structure and antiatherogenic function of apolipoprotein (apo) A‐I, the main protein component of HDL particles. Furthermore, we studied serum lipid profiles and cholesterol efflux capacity in MMP‐8‐deficient mouse model. Incubation of apoA‐I (28 kDa) with activated MMP‐8 yielded 22 kDa and 25 kDa apoA‐I fragments. Mass spectrometric analyses revealed that apoA‐I was cleaved at its carboxyl‐terminal part. Treatment of apoA‐I and HDL with MMP‐8 resulted in significant reduction (up to 84%, P < 0.001) in their ability to facilitate cholesterol efflux from cholesterol‐loaded THP‐1 macrophages. The cleavage of apoA‐I by MMP‐8 and the reduction in its cholesterol efflux capacity was inhibited by doxycycline. MMP‐8‐deficient mice had significantly lower serum triglyceride (TG) levels (P = 0.003) and larger HDL particles compared with wild‐type (WT) mice. However, no differences were observed in the apoA‐I levels or serum cholesterol efflux capacities between the mouse groups. Proteolytic modification of apoA‐I by MMP‐8 may impair the first steps of reverse cholesterol transport, leading to increased accumulation of cholesterol in the vessel walls. Eventually, inhibition of MMPs by doxycycline may reduce the risk for atherosclerotic vascular diseases.—Salminen, A., Äström, P., Metso, J., Soliymani, R., Salo, T., Jauhiainen, M., Pussinen, P. J. Sorsa, T., Matrix metalloproteinase 8 degrades apolipoprotein A‐I and reduces its cholesterol efflux capacity. FASEB J. 29, 1435‐1445 (2015). www.fasebj.org

Quantitative PCR analysis of salivary pathogen burden in periodontitis

Our aim was to investigate the value of salivary concentrations of four major periodontal pathogens and their combination in diagnostics of periodontitis. The Parogene study included 462 dentate subjects (mean age 62.9 ± 9.2 years) with coronary artery disease (CAD) diagnosis who underwent an extensive clinical and radiographic oral examination. Salivary levels of four major periodontal bacteria were measured by quantitative real-time PCR (qPCR). Median salivary concentrations of Porphyromonas gingivalis, Tannerella forsythia, and Prevotella intermedia, as well as the sum of the concentrations of the four bacteria, were higher in subjects with moderate to severe periodontitis compared to subjects with no to mild periodontitis. Median salivary Aggregatibacter actinomycetemcomitans concentrations did not differ significantly between the subjects with no to mild periodontitis and subjects with moderate to severe periodontitis. In logistic regression analysis adjusted for age, gender, diabetes, and the number of teeth and implants, high salivary concentrations of P. gingivalis, T. forsythia, and P. intermedia were significantly associated with moderate to severe periodontitis. When looking at different clinical and radiographic parameters of periodontitis, high concentrations of P. gingivalis and T. forsythia were significantly associated with the number of 4–5 mm periodontal pockets, ≥6 mm pockets, and alveolar bone loss (ABL). High level of T. forsythia was associated also with bleeding on probing (BOP). The combination of the four bacteria, i.e., the bacterial burden index, was associated with moderate to severe periodontitis with an odds ratio (OR) of 2.40 (95% CI 1.39–4.13). When A. actinomycetemcomitans was excluded from the combination of the bacteria, the OR was improved to 2.61 (95% CI 1.51–4.52). The highest OR 3.59 (95% CI 1.94–6.63) was achieved when P. intermedia was further excluded from the combination and only the levels of P. gingivalis and T. forsythia were used. Salivary diagnostics of periodontitis has potential especially in large-scale population studies and health promotion. The cumulative strategy appears to be useful in the analysis of salivary bacteria as markers of periodontitis.

Genetic Variants Contributing to Circulating Matrix Metalloproteinase 8 Levels and Their Association With Cardiovascular Diseases: A Genome-Wide Analysis

Background— Matrix metalloproteinase 8 (MMP-8) is a proinflammatory enzyme expressed mainly by neutrophils. Elevated serum and plasma concentrations of MMP-8 are associated with the risk for and outcome of cardiovascular diseases (CVDs). The origin of circulating MMP-8 is not completely clear. Methods and Results— We performed a genome-wide association study of serum MMP-8 levels in 2 populations comprising altogether 6049 individuals. Moreover, we studied whether MMP-8–associated variants are linked to increased risk of CVDs and overall mortality in >20 000 subjects. The strongest association with serum MMP-8 was found in locus 1q31.3, containing the gene for complement factor H (lead single nucleotide polymorphism: rs800292; P=2.4×10–35). In functional experiments, activation of the alternative pathway of complement in the carriers of rs800292 minor allele (Ile62 in factor H) led to decreased release of MMP-8 from neutrophils compared with the major allele (Val62 in factor H). Another association was detected in 1q21.3, containing genes S100A8, S100A9, and S100A12 (strongest association: rs1560833; P=5.3×10–15). The minor allele of rs1560833 was inversely associated with CVD (odds ratio [95% confidence interval]: 0.90 [0.82–0.99]; P=0.032) and the time to incident CVD event (hazard ratio [95% confidence interval]: 0.91 [0.84–0.99]; P=0.032) in men but not in women. Conclusions— According to our results, the activation of the alternative pathway of the complement system strongly contributes to serum MMP-8 concentration. Genetic polymorphism in S100A9–S100A12–S100A8 locus affects serum and plasma MMP-8 and shows a suggestive association with the risk of CVDs. Our results show that genetic variation determines a significant portion of circulating MMP-8 concentrations.

Salivary biomarkers in association with periodontal parameters and the periodontitis risk haplotype

Genetic factors play a role in periodontitis. Here we examined whether the risk haplotype of MHC class III region BAT1-NFKBIL1-LTA and lymphotoxin-α polymorphisms associate with salivary biomarkers of periodontal disease. A total of 455 individuals with detailed clinical and radiographic periodontal health data were included in the study. A 610 K genotyping chip and a Sequenom platform were used in genotyping analyses. Phospholipid transfer protein activity, concentrations of lymphotoxin-α, IL-8 and myeloperoxidase, and a cumulative risk score (combining Porphyromonas gingivalis, IL-1β and matrix metalloproteinase-8) were examined in saliva samples. Elevated IL-8 and myeloperoxidase concentrations and cumulative risk scores associated with advanced tooth loss, deepened periodontal pockets and signs of periodontal inflammation. In multiple logistic regression models adjusted for periodontal parameters and risk factors, myeloperoxidase concentration (odds ratio (OR); 1.37, P = 0.007) associated with increased odds for having the risk haplotype and lymphotoxin-α concentration with its genetic variants rs2857708, rs2009658 and rs2844482. In conclusion, salivary levels of IL-8, myeloperoxidase and cumulative risk scores associate with periodontal inflammation and tissue destruction, while those of myeloperoxidase and lymphotoxin-α associate with genetic factors as well.