Hideaki Tai

Polymorphisms in the IL-6 receptor (IL-6R) gene: strong evidence that serum levels of soluble IL-6R are genetically influenced.

We have investigated the association of the recently identified IL6R polymorphisms with the serum levels of soluble IL-6 receptor (sIL-6R). sIL-6R is generated by shedding of the membrane-bound receptor (IL-6Rα) or alternative mRNA splicing. In total, 115 healthy volunteers were genotyped, with 70 of them analyzed for sIL-6R levels. Using the PCR/RFLP methods, two important polymorphic sites were selected for genotyping: the 48892A/C (D358A) in exon 9 and the −183G/A in the promoter region. In exon 9, C allele carriers had higher sIL-6R level (P<0.0001) showing that this sequence variation, which corresponds to the proteolytic cleavage site of IL-6Rα, strongly influences the serum sIL-6R levels. In the promoter region, G allele carriers had lower sIL-6R levels (P<0.0082) compared with the A allele carriers. This could be attributed to the linkage disequilibrium (D′=0.54, χ2=51.3, P<0.0001) between the −183G/A and the 48892A/C gene polymorphisms.

The effect of periodontal treatment on serum leptin, interleukin-6, and C-reactive protein.

BACKGROUND Previous studies suggest that periodontitis is closely related to obesity and metabolic syndrome. Leptin, a pleiotrophic hormone produced by adipose tissue, has been reported to be related to periodontitis. This study investigates the effects of periodontal treatment on the serum levels of leptin and other cytokines in patients with chronic periodontitis (CP). METHODS Serum samples were taken from 33 CP patients (22 non-smokers, 11 smokers) and 18 healthy subjects. The serum leptin, adiponectin, tumor necrosis factor-alpha, interleukin (IL)-6, and C-reactive protein (CRP) levels were measured before and after non-surgical periodontal treatment. RESULTS Significant differences between healthy and CP patients were found in serum leptin, IL-6, and CRP levels (P = 0.0018, P = 0.0064, and P = 0.0095, respectively). The serum leptin level was associated with mean probing depth, mean clinical attachment level, mean alveolar bone loss, and body mass index. There were significant associations between serum leptin levels and IL-6 and CRP levels. After non-surgical periodontal treatment, serum leptin, IL-6, and CRP levels were significantly decreased (mean +/- SD before and after, P value, respectively: leptin, 8.02 +/- 5.5, 7.10 +/- 4.4, P = 0.015; IL-6, 1.73 +/- 1.02, 1.36 +/- 0.73, P = 0.048; and CRP, 802.0 +/- 1065, 491.2 +/- 479.3, P = 0.047). CONCLUSIONS Periodontal treatment is effective in reducing serum leptin, IL-6, and CRP levels. The results suggest that leptin, IL-6, and CRP could be mediating factors that connect metabolic syndrome and periodontitis.

Single-nucleotide Polymorphism in the CD14 Promoter and Periodontal Disease Expression in a Japanese Population

It has been reported that there is a relationship between a single-nucleotide polymorphism (SNP) in the promoter region of the CD14 gene at position -159 (C→T) and infectious diseases. The aim of the present study was to test the hypthesis that expression of this SNP correlates with periodontal disease in a Japanese population. The CD14 genotype was determined in 163 subjects with periodontitis and in 104 age- and gender-matched control subjects without periodontitis. The genotype distribution and allele frequency within the periodontitis patients were not significantly different from those of control subjects. There was, however, a significant difference in the genotype distribution between young patients (< 35 yrs) and older patients (≥ 35 yrs). These findings suggest that CD14 -159C/T polymorphism is not related to the development of periodontitis in a Japanese population, but that, within the periodontitis subjects, expression of the SNP may be related to early disease activity.

Genetic Risk Factors for Periodontitis in a Japanese Population

Genetic variants at multiple loci have been shown to be associated with susceptibility to periodontitis. To better assess the genetic risk factors for periodontitis, we performed a case-control study in 319 Japanese individuals with periodontitis (172 aggressive and 147 chronic disease) and 303 race-matched healthy control individuals. Thirty-five functional gene polymorphisms that had been previously associated with immune responses were genotyped. For all gene polymorphisms tested, no significant differences were observed in the allele frequencies of persons with aggressive, chronic, and combined (aggressive and chronic) periodontitis, compared with control individuals. Multiple logistic regression analysis revealed a significant association of the vitamin D receptor +1056 T/C polymorphism with susceptibility to chronic periodontitis, after adjustment for age, gender, and smoking status (P = 0.002). These results suggest that none of the polymorphisms tested was strongly associated with periodontitis in a Japanese population. However, the vitamin D receptor +1056 polymorphism may be related to chronic periodontitis.

Effects of treatment on soluble tumour necrosis factor receptor type 1 and 2 in chronic periodontitis

AIM We reported that soluble tumour necrosis factor receptor type 2 (sTNFR2)/type 1 (sTNFR1) ratios in gingival crevicular fluid (GCF) decreased as the severity of chronic periodontitis (CP) increased. This study investigated the effects of the periodontal treatment on TNF-alpha, sTNFR1 and R2 in GCF and serum of CP patients. MATERIAL AND METHODS Thirty-five serum and 90 GCF samples were obtained from 35 CP patients (23 non-smokers and 12 smokers) at baseline and after treatment. The levels of TNF-alpha, sTNFR1 and R2 in serum and GCF were quantified by enzyme-linked immunosorbant assay. RESULTS No significant differences were found in the serum levels of TNF-alpha, sTNFR1 and R2 and the ratio of sTNFR2/R1 between baseline and after treatment. After treatment, sTNFR1 and R2 levels in GCF of non-smokers and smokers were significantly decreased compared with baseline. However, the sTNFR2/R1 ratio was significantly increased (non-smoker: 0.56+/-0.03-0.84+/-0.03, p<0.0001; smoker: 0.59+/-0.06-0.85+/-0.04, p=0.0019). There were no significant differences between non-smoking and smoking CP groups in serum and GCF. CONCLUSION The ratio of sTNFR2/R1 in GCF significantly increased after treatment, and could be related to the clinical state of CP.

Assessment of 14 functional gene polymorphisms in Japanese patients with oral lichen planus: a pilot case-control study

Oral lichen planus (OLP) is a refractory mucosal disease. Its pathogenesis is thought to involve immunologic and genetic alterations. To gain a better understanding of the genetic risk factors, the authors evaluated associations between 14 functional gene polymorphisms and OLP. 32 Japanese patients with OLP and 99 unrelated healthy Japanese controls were genotyped for 14 single nucleotide polymorphisms (SNPs) of genes that regulate host immune responses. Genotyping was performed with a modified version of the serial invasive signal amplification reaction. A trend towards over-representation of tumor necrosis factor receptor 2 (TNFR2) +587 G allele was found in the patients compared with the controls (allele frequency: P=0.049). The other 13 SNPs were unassociated with OLP. These results suggest that TNFR2 +587 gene polymorphism may be associated with susceptibility to OLP.

α2 Integrin +807 polymorphism in drug-induced gingival overgrowth

α2 integrin on fibroblasts is reported to play an important role in the induction of drug-induced gingival overgrowth, which is characterized by excessive accumulation of type I collagen in gingival connective tissue. Silent polymorphism 807 T/C within the α2 integrin gene is associated with high/low α2 integrin expression. The aim of this study was to test the hypothesis that expression of α2 integrin 807 T/C polymorphism correlates with drug-induced gingival overgrowth. A case-control study comparing 136 subjects taking calcium channel blockers (72 with vs. 64 without drug-induced gingival overgrowth) demonstrated that the frequency of the +807 C allele was significantly higher in the case group than in the controls (odds ratio, 3.61; 95% confidence interval, 2.14 – 6.10; P < 0.05). The present findings suggest that the α2 +807 C allele is one of the genetic risk factors for drug-induced gingival overgrowth.

Assessment of Chromosome 19 for Genetic Association in Severe Chronic Periodontitis

BACKGROUND A genome-association study is a powerful tool for analyzing small gene effects in complex diseases such as chronic periodontitis (CP), although the cost of analysis is prohibitive. We designed a study using the DNA pooling method, which could be a breakthrough in lowering such costs. This study was conducted to assess the genetic association in severe CP in a Japanese population. METHODS We adopted a DNA pooling method by genotyping 454 densely spaced microsatellite (MS) markers in chromosome 19 as a pilot study, with the possibility of future use in a whole-genome study. This can reduce the high cost and technical burden, which is generally unavoidable in a genomic association study. Pooled DNA samples from 300 case subjects, 300 control subjects, and 200 systemically healthy subjects were screened by genotyping MS markers. The case-control association in the candidate region was analyzed by individual typing of MS and single nucleotide polymorphisms (SNPs). RESULTS The single MS marker allele 17 of 1902G31 was isolated in association with severe CP (P = 0.0012 for 2 x 2; P <0.046 for 2 x m, where m refers to the number of polymorphic alleles observed in a population). No other SNP or MS polymorphism hypothesized to affect biologic functions in the critical region was found in the linkage disequilibrium block analysis. CONCLUSIONS We efficiently isolated the susceptible locus for severe CP in chromosome 19 and identified a useful marker to evaluate the risk for disease. This approach can be applied to a whole-genome study in severe CP.

The FcγRIIa polymorphism influences production of interleukin-1 by mononuclear cells

The functional bi‐allelic polymorphism of immunoglobulin G (IgG) Fc receptor (FcγR) IIa influences the efficiency of human IgG2 binding. Our previous study showed that the high affinity FcγRIIa genotype (‐H/H131) was associated with periodontitis risk. As interleukin‐1 (IL‐1) is one of the major causes of periodontal tissue destruction, it is hypothesized that the FcγRIIa‐H/H131cross‐linking could induce an increased IL‐1 release by mononuclear cells. In this study, we evaluated the intracellular expressions of IL‐1β in CD14 positive cells upon stimulation with human IgG2 by flow cytometry. FcγRIIa‐H/H131 subjects exhibited a higher percentage of IL‐1β‐producing cells than FcγRIIa‐R/H131 and ‐R/R131 subjects (P < 0.05). These results support the concept that FcγRIIa genotype may affect IL‐1β production, possibly leading to interindividual differences in periodontitis risk.

Analysis of Tumor Necrosis Factor Receptor 1 and 2 Gene Polymorphisms in Japanese Patients with Generalized Aggressive Periodontitis.

歯周炎は多因子疾患の一つと考えられ, なかでも侵襲性 (早期発症型) 歯周炎の疾患感受性には遺伝子多型の関与が示唆されている。一方で, 歯周炎局所でTNFαのシグナル伝達・調節機能を担うTNFレセプター (TNFR) の機能についても着目されている。そこで今回, 日本人におけるTNFRの遺伝子多型と侵襲性歯周炎との関連性について検討した。インフォームドコンセントを得た日本人広汎性侵襲性歯周炎患者45名および年齢を適合させた健常者100名を対象とした。5カ所の遺伝子多型はそれぞれTNFR2 (VNTR) はPCR法, TNFR1 (-383; A/C), (+36; A/G), TNFR2 (+587; T/G) はPCR-RFLP法, TNFR2 (+694; G/A) はPCR-SSCP法にて検出した。統計学的解析はカイ2乗検定, フィッシャーの直接確率法, 同等性のΔ検定とさらにMante1-Haensze1法による補正を行った。その結果, TNFR1 (-383) ではCアレルの頻度が患者群に有意に低いことを認めた。さらに患者群と健常者群では, 3カ所のTNFR2アレル頻度に同等性が認められ, 交絡因子で補正後もTNFR2 (+587) および (VNTR) には同等性が有意に認められた。以上の結果より, 広汎性侵襲性歯周炎にはTNFR1 (-383) 遺伝子多型が関連する一方で, TNFR2 (+587), (VNTR) には関連性が乏しい可能性が示唆された。