Buket Han Saygan

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.

Effect of periodontal treatment on receptor activator of NF-κB ligand and osteoprotegerin levels and relative ratio in gingival crevicular fluid.

AIM Receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) have an established role in the pathogenesis of periodontitis, which is characterized by an increased RANKL/OPG ratio. The present study aims to investigate changes of RANKL, OPG and their relative ratio in gingival crevicular fluid (GCF) of periodontitis patients after non-surgical periodontal treatment. MATERIALS AND METHODS GCF was obtained from chronic periodontitis (n=14), generalized aggressive periodontitis (G-AgP; n=13) patients at baseline. The patients received scaling and root planing and were recalled after 2, 3 and 4 months for follow-up clinical examination and sampling. The total amounts and concentrations of RANKL and OPG in GCF were measured by enzyme-linked immunosorbent assay, and their relative ratio was calculated. RESULTS The RANKL/OPG ratio remained unchanged and did not correlate with clinical parameters throughout the monitoring period, despite the improved clinical outcome. This trend was similar in both chronic and G-AgP. CONCLUSIONS Although the RANKL/OPG ratio has a potential diagnostic value for untreated periodontitis, it may not be a suitable predictor of clinically successful treatment outcome. As conventional therapy does not negatively modulate this ratio, the host could still be susceptible to further periodontal tissue destruction, warranting the consideration of adjunctive treatments.

Angiotensin-converting enzyme (ACE), angiotensinogen (AGT), and angiotensin II type 1 receptor (AT1R) gene polymorphisms in generalized aggressive periodontitis

AIM Host response to periodontopathic microorganisms can be modulated by genetic factors. Accumulated evidence highlighted the role of renin-angiotensin system (RAS) in inflammatory response thus potential implication of this molecular system in the pathogenesis of periodontitis can be suggested. The present study investigated common genetic variants of molecules within the RAS family namely angiotensin-converting enzyme (ACE), angiotensinogen (AGT) and angiotensin II type 1 receptor (AT1R) in relation to generalized aggressive periodontitis (G-AgP). METHODS DNA was obtained from peripheral blood of 103 G-AgP patients and 100 periodontally healthy subjects. ACE I/D, AGT M235T and AT1R A1166C polymorphisms were genotyped by polymerase chain reaction and restriction fragment length polymorphism method. Chi-square, ANOVA and logistic regression were used in statistical analyses. RESULTS Both ACE I/D and AT1R polymorphisms were similar in G-AgP and healthy groups (p>0.05). G-AgP subjects exhibited decreased AGT TT genotype and T allele frequency as compared to healthy subjects (p<0.05). The same trend was also observed in the nonsmoker subgroup regarding investigated RAS polymorphisms. CONCLUSIONS Present findings suggest that AGT M235T TT genotype and T allele might be associated with decreased risk for G-AgP in Turkish population.

Renin-angiotensin gene polymorphisms in relation to severe chronic periodontitis.

AIM Evidence suggests that the ultimate product of the renin-angiotensin system (RAS), angiotensin II, exerts inflammatory actions. The present study aimed to evaluate the inter-relation between gene polymorphisms of the RAS components; angiotensin converting enzyme (ACE), angiotensinogen (AGT) and angiotensin II type-I receptor (AT1R), and severe chronic periodontitis (CP). MATERIAL AND METHODS DNA was obtained from peripheral blood of 90 CP patients and 126 periodontally healthy subjects, and the clinical parameters were recorded. ACE I/D, AGT M235T and AT1R A1166C polymorphisms were genotyped by the PCR-RFLP method. Chi-square, anova and logistic regression methods were used in statistical analyses. RESULTS The frequency of the ACE D allele was significantly lower in the CP group than the healthy group (p(corr)=0.015). CP subjects exhibited increased C allele carriage and C allele frequency of the AT1R gene (p(corr)=0.03 and p(corr)=0.03, respectively). All clinical parameters of CP patients were found to be similar in variant allele-carrying and non-carrying subjects (p>0.05). CONCLUSIONS The present findings suggest that ACE I/D and AT1R polymorphisms might be associated with susceptibility to CP but not with disease severity. The D allele of ACE I/D might be associated with decreased, whereas the C variant of AT1R A1166C might be associated with an elevated risk for CP in Turkish population.

Gene expression of transcription factor NFATc1 in periodontal diseases

Belibasakis GN, Emingil G, Saygan B, Turkoglu O, Atilla G, Bostanci N. Gene expression of transcription factor NFATc1 in periodontal diseases. APMIS 2011; 119: 167–172.

Calcium, vitamin D supplements with or without alendronate and supragingival calculus formation in osteoporotic women: a preliminary study.

Objectives: Long-term calcium intake is related to the formation of urinary stones. Structure and composition of kidney and gallstones are similar to dental calculus. Saliva is the source of calcium for supragingival dental calculus formation. The aim of this preliminary study was to evaluate the possible effects of long-term calcium and vitamin D supplementation with or without alendronate administration on salivary electrolyte concentrations and supragingival calculus formation in osteoporotic women. Methods: Thirty-one female patients with osteoporosis for at least 3 years participated in this study. Eighteen women were taking calcium plus vitamin D plus alendronate, while 13 women were taking only calcium plus vitamin D supplements. Eleven systemically healthy women volunteered for the control group. Whole saliva samples were collected from all women before initiation of any periodontal intervention. Plaque index, probing depth, clinical attachment level, bleeding on probing, and calculus index were recorded at six sites/tooth. Salivary concentrations of ionic calcium, potassium, magnesium and sodium were determined by atomic absorption spectrophotometer. Results were evaluated statistically by non-parametric tests. Results: No significant differences were found in clinical parameters or results of saliva analysis between the study groups (p > 0.05). Conclusion: Within the limits of this preliminary study, it is suggested that long-term calcium and vitamin D supplementation with or without alendronate does not appear to have a significant effect on supragingival calculus formation or saliva total calcium, potassium, magnesium and sodium concentrations. Larger-scale studies investigating the possible effects of various treatment modalities of osteoporosis on supragingival calculus formation are required to better clarify this issue.