Tetsuo Kobayashi

Interleukin-6 Gene Promoter Methylation in Rheumatoid Arthritis and Chronic Periodontitis

BACKGROUNDnMethylation status of the cytokine genes may play a role in the pathogenesis of inflammatory diseases, such as rheumatoid arthritis (RA) and chronic periodontitis (CP). This study was undertaken to evaluate whether the DNA methylation profile of the interleukin-6 (IL-6) gene promoter was unique to individuals with RA and CP.nnnMETHODSnThe study participants consisted of 30 patients with RA, 30 patients with CP, and 30 age-, sex-, and smoking status-balanced healthy controls. Genomic DNA isolated from peripheral blood was modified by sodium bisulfite and analyzed for DNA methylation levels of IL-6 gene with direct sequencing. Levels of IL-6 were determined by an enzyme-linked immunosorbent assay.nnnRESULTSnThe region of IL-6 gene promoter from -1200 to +27 bp was shown to contain 19 CpG motifs. The methylation levels of the CpG motif at -74 bp were significantly lower in patients with RA and CP than those in controls (P = 0.0001). Both levels of serum IL-6 and IL-6 production by mononuclear cells were significantly different between individuals with and without the methylation at -74 bp (P = 0.03). The +19 bp motif exhibited differential levels of the methylation among the groups, which was not associated with serum levels of IL-6. The other 17 CpG motifs exhibited comparable levels of the methylation between the groups.nnnCONCLUSIONnThese results suggest that hypomethylated status of a single CpG in the IL-6 promoter region may lead to increased levels of serum IL-6, implicating a role in the pathogenesis of RA and CP.

Periodontal Treatment Decreases Levels of Antibodies to Porphyromonas gingivalis and Citrulline in Patients With Rheumatoid Arthritis and Periodontitis

BACKGROUNDnPorphyromonas gingivalis has been implicated as an etiologic agent of rheumatoid arthritis (RA) because of the expression of peptidylarginine deiminase. The present study evaluates whether periodontal treatment may affect serum antibodies to P. gingivalis and citrulline levels in relation to disease activity of RA.nnnMETHODSnFifty-five patients with RA were randomly assigned to receive oral hygiene instruction and supragingival scaling (treatment group, n = 26) or no periodontal treatment (control group, n = 29). Periodontal and rheumatologic parameters and serum levels of cytokine and inflammatory markers citrulline and immunoglobulin (Ig)G to P. gingivalis were examined at baseline and 8 weeks later.nnnRESULTSnBoth groups did not differ statistically in any parameters except percentage of sites with probing depth and clinical attachment level ≥ 4 mm at baseline. The treatment group exhibited a significantly greater decrease in disease activity score including 28 joints using C-reactive protein (DAS28-CRP) (P = 0.02), serum levels of IgG to P. gingivalis hemin binding protein (HBP)35 (P = 0.04), and citrulline (P = 0.02) than the control group. Serum levels of IgG to P. gingivalis HBP35 were significantly correlated positively with those of anti-cyclic citrullinated peptide antibodies (P = 0.0002). The same correlation was obtained between serum levels of IgG to P. gingivalis-sonicated extracts and those of rheumatoid factor (P = 0.02).nnnCONCLUSIONSnThese results suggest that supragingival scaling decreases DAS28-CRP and serum levels of IgG to P. gingivalis HBP35 and citrulline in patients with RA. These observations may reflect a role of P. gingivalis in the protein citrullination, which is related to the pathogenesis of RA.

Antibody responses to periodontopathic bacteria in relation to rheumatoid arthritis in Japanese adults.

BACKGROUNDnPeriodontopathic bacteria have been implicated as contributory to the etiology of rheumatoid arthritis (RA). Anticyclic citrullinated peptide (CCP) antibodies and rheumatoid factor (RF) were shown to be associated with RA. This study examines whether serum levels of antibodies to periodontopathic bacteria may affect clinical and laboratory profiles of RA.nnnMETHODSnThe study participants consisted of 80 patients with RA, and 38 age-, sex-, smoking status-, and periodontal condition-balanced healthy controls. After periodontal and rheumatologic examination, serum levels of immunoglobulin G (IgG) antibodies to Porphyromonas gingivalis (Pg), Prevotella intermedia, Aggregatibacter actinomycetemcomitans (Aa) (previously Actinobacillus actinomycetemcomitans), and Eikenella corrodens (Ec) and those of anti-CCP antibodies and RF were determined by an enzyme-linked immunosorbent assay.nnnRESULTSnPatients with RA showed significantly higher levels of anti-Pg and anti-CCP antibodies than controls (P = 0.04 and P <0.0001). In contrast, IgG responses to Aa and Ec in patients with RA were significantly lower than those in controls (P <0.0001 and P = 0.0001). Multiple logistic regression analysis revealed a significant association of anti-Pg and anti-Aa IgG responses with RA, after adjustment for age, sex, and smoking (P = 0.005 and P = 0.02). Anti-Pg titer displayed a significant correlation with RF levels, probing depth, and clinical attachment level (P = 0.03, P = 0.03, and P = 0.02).nnnCONCLUSIONnThese results suggest that serum levels of anti-Pg IgG antibodies were associated with RA, and might affect serum levels of RF and periodontal condition in patients with RA.

Serum Cytokine and Periodontal Profiles in Relation to Disease Activity of Rheumatoid Arthritis in Japanese Adults

BACKGROUNDnRheumatoid arthritis (RA) and periodontitis are common chronic inflammatory conditions and share many pathologic features. A similar profile of cytokines is involved in the pathogenesis of the two diseases. The relationship between the disease activity of RA and the periodontal condition remains unclear. This study examines whether the disease activity of RA affects serum cytokine and periodontal profiles.nnnMETHODSnThe study subjects consisted of 84 Japanese adults with RA and 22 race-matched control individuals. After periodontal and rheumatologic examination, the disease activity of RA was determined with the Disease Activity Score including 28 joints using C-reactive protein (DAS28-CRP). Serum levels of cytokines including interleukin (IL)-1beta, IL-6, IL-12, IL-12 p40, IL-18, and tumor necrosis factor-alpha (TNF-alpha) were determined by an enzyme-linked immunosorbent assay. High-sensitive CRP was also measured with a latex particle-enhanced nephelometric method.nnnRESULTSnOf 84 patients with RA, 28 and 56 patients exhibited low and moderate to high disease activity, respectively. Serum levels of IL-6, TNF-alpha, and CRP were significantly different between the two groups (P <0.05). Additionally, a significant correlation was observed between DAS28-CRP and percentage of sites with bleeding on probing (BOP) (P = 0.008) and between serum TNF-alpha levels and percentage of sites with BOP (P = 0.01) in 56 patients with RA with moderate to high activity.nnnCONCLUSIONnThese results suggest that the disease activity of RA correlated with serum levels of IL-6, TNF-alpha, and CRP, and it might influence BOP in the patients with moderate to high disease activity.

Cytokine Gene Polymorphisms Associated With Rheumatoid Arthritis and Periodontitis in Japanese Adults

BACKGROUNDnCytokines play a major role in the pathogenesis of rheumatoid arthritis (RA) and periodontitis. Both diseases were previously shown to be partly influenced by cytokine gene polymorphisms. Therefore, we evaluated whether the distributions of the cytokine genotypes were unique to subjects with both diseases.nnnMETHODSnThe study subjects consisted of Japanese adults with RA (RA group; n = 153), periodontitis only (P group; n = 117), and healthy individuals (H group; n = 108). Clinical periodontal condition was defined by measurements of probing depth, clinical attachment level, and bleeding on probing. Genomic DNA was isolated from peripheral blood and analyzed for the determination of 16 gene polymorphisms encoding interleukin (IL)-1, -2, -4, -6, and -10, tumor necrosis factor-alpha, and transforming growth factor-beta 1.nnnRESULTSnThe frequency of patients with RA who exhibited periodontitis was 89.5% (RA + P group; n = 137). No significant differences were observed in any of the frequencies of cytokine genotypes and alleles among the subject groups. After adjustment for age, gender, and smoking status, multiple logistic regression analysis revealed a significant difference in the distribution of IL-1B +3954 genotypes between RA + P and P groups (P = 0.006) and between RA + P and H groups (P = 0.008).nnnCONCLUSIONnJapanese individuals with RA and periodontitis may exhibit different distributions of IL-1B +3954 genotypes than healthy controls and subjects with periodontitis only.

Periodontal and serum protein profiles in patients with rheumatoid arthritis treated with tumor necrosis factor inhibitor adalimumab.

BACKGROUNDnTumor necrosis factor (TNF)-α inhibitor has been shown to affect the periodontal condition of patients with rheumatoid arthritis (RA). The aim of the present study is to assess the effect of a fully humanized anti-TNF-α monoclonal antibody, adalimumab (ADA), on the periodontal condition of patients with RA and to compare serum protein profiles before and after ADA therapy.nnnMETHODSnThe study participants consisted of 20 patients with RA treated with ADA. Clinical periodontal and rheumatologic parameters and serum cytokine levels were evaluated at baseline and 3 months later. Serum protein spot volume was examined with two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis. Proteins with significant difference in abundance before and after ADA therapy were found and identified using mass spectrometry and protein databases.nnnRESULTSnThe patients showed a significant decrease in gingival index (P = 0.002), bleeding on probing (P = 0.003), probing depth (P = 0.002), disease activity score including 28 joints using C-reactive protein (P <0.001), and serum levels of TNF-α (P <0.001) and interleukin-6 (P <0.001) after ADA medication, although plaque levels were comparable. Among a total of 495 protein spots obtained, nine spots were significantly decreased in abundance at reassessment, corresponding to complement factor H, phospholipase D, serum amyloid A, complement component 4, and α-1-acid glycoprotein (P <0.01).nnnCONCLUSIONnThese results suggest a beneficial effect of ADA therapy on the periodontal condition of patients with RA, which might be related to differences in serum protein profiles before and after ADA therapy.

Assessment of Interleukin-6 Receptor Inhibition Therapy on Periodontal Condition in Patients With Rheumatoid Arthritis and Chronic Periodontitis

BACKGROUNDnOverproduction of interleukin (IL)-6 may play a pathologic role in rheumatoid arthritis (RA) and chronic periodontitis (CP). The present study assesses IL-6 receptor (IL-6R) inhibition therapy on the periodontal condition of patients with RA and CP.nnnMETHODSnThe study participants were 28 patients with RA and CP during treatment with IL-6R inhibitor, and 27 patients with RA and CP during treatment without IL-6R inhibitor. Periodontal and rheumatologic parameters and serum levels of cytokine and inflammatory markers and immunoglobulin G against periodontopathic bacteria were examined after medication with IL-6R inhibitor for 20.3 months on average (T1) and again 8 weeks later (T2).nnnRESULTSnNo differences were observed between the groups in any parameter values at T1, except for serum IL-6 levels. The anti-IL-6R group showed a significantly greater decrease in gingival index, bleeding on probing (BOP), probing depth (PD), clinical attachment level (CAL), and serum levels of IL-6 and matrix metalloproteinase (MMP)-3 from T1 to T2 than the control group (P <0.05). A significant correlation was found between changes in serum anticyclic citrullinated peptide levels and those in PD and CAL in the anti-IL-6R group (P <0.05), whereas both groups exhibited a significant association between changes in serum MMP-3 levels and those in BOP (P <0.05).nnnCONCLUSIONnChanges in periodontal and serum parameter values were different between the patients with RA and CP during treatment with and without IL-6R inhibitor.

Host Responses in the Link Between Periodontitis and Rheumatoid Arthritis

Periodontitis and rheumatoid arthritis (RA) are common chronic inflammatory conditions and share many clinical and pathologic features. There is evidence to suggest that similar profiles of cytokine genotypes and their coding proteins are involved in the pathogenesis of periodontitis and RA. In particular, constitutive overproduction of pro-inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), has been implicated to play a pathologic role in the two inflammatory diseases. Results from studies with animal and human subjects have suggested an improvement of periodontal inflammatory condition after treatment with TNF-α inhibitors. Likewise, IL-6 receptor inhibition therapy has been suggested to have an effect on control of periodontal inflammation in patients with RA. In the present review, we provide an overview of studies showing the pathological role of cytokines in the linkage between periodontitis and RA, and further summarize the current studies assessing the effect of cytokine targeted therapy on periodontal condition.

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.

Expression of anti-Porphyromonas gingivalis peptidylarginine deiminase immunoglobulin G and peptidylarginine deiminase-4 in patients with rheumatoid arthritis and periodontitis

BACKGROUND AND OBJECTIVEnAutoimmunity against citrullinated proteins through peptidylarginine deiminase (PAD) may be involved in the pathophysiology of rheumatoid arthritis (RA). The present study evaluated the serum levels of antibodies to citrullinated proteins and to Porphyromonas gingivalis PAD (PPAD), and the endogenous expression of PAD-4, in individuals with and without RA, as well as before and after periodontal treatment.nnnMATERIAL AND METHODSnThe study participants consisted of 52 patients with RA (RA group) and 26 age-, gender- and smoking status-matched healthy controls (non-RA group). Of the 52 patients, 26 were randomly assigned to receive oral hygiene instruction and supragingival scaling (RA subgroup). After periodontal and rheumatologic assessments, the serum levels of anti-cyclic citrullinated peptide (CCP) immunoglobulin G (IgG), anti-PPAD IgG and PAD-4 were determined using ELISA.nnnRESULTSnThe serum levels of anti-CCP IgG and anti-PPAD IgG were significantly higher in the RA group than in the non-RA group (p < 0.001 and p = 0.03). A significant, positive correlation was observed between the serum levels of anti-PPAD IgG and anti-CCP IgG (p = 0.04), but not between the serum levels of PAD-4 and anti-CCP IgG. Multiple logistic regression analyses revealed a significant association between anti-PPAD IgG responses and RA after adjustment for age, gender and smoking (p = 0.004). Supragingival scaling significantly improved the periodontal condition and disease activity of RA (p < 0.05), but failed to decrease the serum levels of anti-CCP IgG, anti-PPAD IgG and PAD-4 after 2 mo of treatment.nnnCONCLUSIONnThese results might suggest an association between anti-PPAD IgG and anti-CCP IgG responses, implicating a role for PPAD in protein citrullination in patients with RA and periodontitis.