Tülay Yucel-Lindberg

Periodontitis in RA-the citrullinated enolase connection.

Autoimmunity in rheumatoid arthritis (RA) is characterized by an antibody response to citrullinated proteins. Two of the risk factors for RA—HLA-DRB1 shared epitope alleles and smoking—are also associated with periodontitis, which is largely, but not exclusively, caused by Porphyromonas gingivalis infection. Furthermore, RA and periodontitis have a similar pathophysiology, characterized by destructive inflammation. The citrullination of proteins by P. gingivalis and the subsequent generation of autoantigens that drive autoimmunity in RA represents a possible causative link between these two diseases. Antibodies directed towards the immunodominant epitope of human citrullinated α-enolase cross-react with a conserved sequence on citrullinated P. gingivalis enolase. On the basis of this cross-reactivity, in this Perspectives article we explore the hypothesis of molecular mimicry in the etiology of RA, with citrullinated enolase as the specific antigen involved.

Short-term effect of chewing gums containing probiotic Lactobacillus reuteri on the levels of inflammatory mediators in gingival crevicular fluid

Objective. To investigate the effect of a chewing gum containing probiotic bacteria on gingival inflammation and the levels of selected inflammatory mediators in gingival crevicular fluid (GCF). Material and Methods. Forty-two healthy adults with moderate levels of gingival inflammation entered a double-blind placebo-controlled study design. The subjects were randomly assigned to one of three parallel arms: Group A/P was given one active and one placebo gum daily, Group A/A received two active chewing gums, and Group P/P two placebo gums. The chewing gums contained two strains of Lactobacillus reuteri: ATCC 55730 and ATCC PTA 5289 (1×108 CFU/gum, respectively). The subjects were instructed to chew the gums for 10 min over the course of 2 weeks. Bleeding on probing (BOP) and GCF sampling were conducted at baseline and after 1, 2 and 4 weeks. The levels of IL-1β, TNF-α, IL-6, IL-8 and IL-10 were determined using luminex technology and multiplex immunoassay kits. Results. BOP improved and GCF volume decreased in all groups during the chewing period, but the results were statistically significant (p<0.05) only in Groups A/P and A/A. The levels of TNF-α and IL-8 decreased significantly (p<0.05) in Group A/A compared with baseline after 1 and 2 weeks, respectively. A non-significant decreasing tendency was also observed concerning IL-1β during the chewing period. The levels of IL-6 and IL-10 were unaffected in all groups after 1 and 2 weeks. Conclusions. The reduction of pro-inflammatory cytokines in GCF may be proof of principle for the probiotic approach combating inflammation in the oral cavity.

Inflammatory mediators in the pathogenesis of periodontitis

Periodontitis is a chronic inflammatory condition of the periodontium involving interactions between bacterial products, numerous cell populations and inflammatory mediators. It is generally accepted that periodontitis is initiated by complex and diverse microbial biofilms which form on the teeth, i.e. dental plaque. Substances released from this biofilm such as lipopolysaccharides, antigens and other virulence factors, gain access to the gingival tissue and initiate an inflammatory and immune response, leading to the activation of host defence cells. As a result of cellular activation, inflammatory mediators, including cytokines, chemokines, arachidonic acid metabolites and proteolytic enzymes collectively contribute to tissue destruction and bone resorption. This review summarises recent studies on the pathogenesis of periodontitis, with the main focus on inflammatory mediators and their role in periodontal disease.

Correlation between TNFa in gingival crevicular fluid and body mass index in obese subjects

The aim of this study was to investigate the relationship between body mass index (BMI kg/m[Formula: See Text]), the inflammatory mediator tumor necrosis factor α (TNFα), and interleukin-8 (IL-8) in gingival crevicular fluid (GCF) from 32 obese subjects aged between 13 and 24 years. Gingival inflammation (GBI %), pathological pocket depths, and alveolar bone loss diagnosed on radiographs were recorded. The GCF was collected from six sites per subject using periopaper, and the volume was determined using Peritron 8000. The levels of TNFα and IL-8 were determined using ELISA kits. Within the whole group, there was no significant relationship between BMI and the variables age, GBI %, number of periodontal pockets, smoking, and the levels of TNFα or IL-8. In subjects with BMI ≥40, however, there was a statistically significant correlation (r=0.74, P<0.01) between the level of TNFα in GCF and BMI. The correlation coefficient between BMI and TNFα in subjects with BMI ≥40 differed significantly (P<0.05) compared to that between subjects with BMI <40. The level of TNFα in GCF was positively correlated (P<0.05) with BMI in subjects with no periodontal pathological pocket. No significant correlation was found between the level of IL-8 and BMI. The results indicate that BMI positively correlates with TNFα in GCF in the group of young subjects with BMI ≥40 as well as in the subjects with no pathological periodontal pocket (≥4 mm) and that TNFα in GCF may be affected by the obese condition through a systemic effect.

Signal Transduction Pathways Involved in the Synergistic Stimulation of Prostaglandin Production by Interleukin-1β and Tumor Necrosis Factor a in Human Gingival Fibroblasts

Accumulating evidence indicates that prostaglandins play an important role in the pathogenesis of periodontal disease. In this study, the effects and interactions between IL-1β and TNFa on prostaglandin production and its regulation were investigated. The cytokines IL-1β and TNFa stimulated prostaglandin E2 (PGE2) and prostacyclin (PGI2) production in gingival fibroblasts. Simultaneous treatment of the cells with IL-1β and TNFa resulted in a synergistic stimulation of PGE2 and PGI2 formation. IL-1β and, to a lesser extent, TNFa stimulated the release of 3H-arachidonic acid (3H-AA), and simultaneous addition of IL-1β and TNFa further increased the release of 3H-AA from pre-labeled gingival fibroblasts. Furthermore, IL-1β and, to a lesser extent, TNFa induced the expression of cyclooxygenase-2 (COX-2) mRNA. Simultaneous addition of IL-1β and TNFa synergistically enhanced COX-2 mRNA levels, accompanied by a corresponding stimulation of PGE2 synthesis. Neither IL-1β, TNFa, nor the combination of these two cytokines affected COX-1 mRNA levels. PMA, known to activate protein kinase C (PKC), enhanced the stimulatory effect of IL-1β, TNFa, and the combination on COX-2 mRNA levels accompanied by a corresponding increase in PGE2 production. The phospholipase A2 (PLA2) inhibitor, BPB, and the PKC inhibitor, BIS, reduced PGE2 production, whereas dexamethasone, indomethacin, and NS-398 completely abolished PGE2 production induced by IL-1β, TNFa, and the combination. The study indicates that the synergistic stimulation of prostaglandin production by IL-1β, and TNFa is mediated partly at the level of COX-2 and partly at the level of PLA2 and that PKC is involved in the signal transduction of the synergy between the two cytokines. The synergy between IL-1β and TNFa may play an important role in the inflammatory processes in gingival tissue in vivo.

Interleukin-1 beta induces expression of cyclooxygenase-2 mRNA in human gingival fibroblasts.

The effect of interleukin-1β (IL-1β) on the expression of cyclooxygenase-1 and −2 (COX-1 and COX-2) mRNA and its relation to prostaglandin E2 (PGE2) biosynthesis in human gingival fibroblasts was studied. IL-1β increased levels of mRNA for COX-2 whereas the COX-1 mRNA level was unaffected. The increased COX-2 mRNA levels were accompanied by enhanced PGE2 formation. The phorbol, 12-myristate 13-acetate (PMA), known to stimulate protein kinase C (PKC), also induced expression of COX-2 mRNA. When gingival fibroblasts were treated simultaneously with IL-1β and PMA, the cytokine IL-1β synergistically increased levels of COX-2 mRNA, accompanied by a corresponding increase in PGE2 biosynthesis. The anti-inflammatory steroid, dexamethasone (DEX) abolished the enhanced expression of COX-2 mRNA as well as PGE2 formation induced by IL-1β, PMA or the combination of IL-1β and PMA. The study indicates that the IL-1β induced PGE2 formation is mediated by an enhanced gene expression of COX-2 in gingival fibroblasts suggesting that the enzyme COX-2 may play an important role in the regulation of prostanoid formation at inflammatory lesions in gingival tissue.

Antibodies to Porphyromonas gingivalis Indicate Interaction Between Oral Infection, Smoking, and Risk Genes in Rheumatoid Arthritis Etiology.

To investigate the role of the periodontal pathogen Porphyromonas gingivalis in the etiology of rheumatoid arthritis (RA) by analyzing the antibody response to the P gingivalis virulence factor arginine gingipain type B (RgpB) in relation to anti–citrullinated protein antibodies (ACPAs), smoking, and HLA–DRB1 shared epitope (SE) alleles in patients with periodontitis, patients with RA, and controls.

Signal pathways JNK and NF-κB, identified by global gene expression profiling, are involved in regulation of TNFα-induced mPGES-1 and COX-2 expression in gingival fibroblasts

BackgroundProstaglandin E2 (PGE2) is involved in several chronic inflammatory diseases including periodontitis, which causes loss of the gingival tissue and alveolar bone supporting the teeth. We have previously shown that tumor necrosis factor α (TNFα) induces PGE2 synthesis in gingival fibroblasts. In this study we aimed to investigate the global gene expression profile of TNFα-stimulated primary human gingival fibroblasts, focusing on signal pathways related to the PGE2-synthesizing enzymes prostaglandin E synthases (PGES), as well as the upstream enzyme cyclooxygenase-2 (COX-2) and PGE2 production.ResultsMicroarray and western blot analyses showed that the mRNA and protein expression of the inflammatory induced microsomal prostaglandin E synthase-1 (mPGES-1) was up-regulated by the cytokine TNFα, accompanied by enhanced expression of COX-2 and increased production of PGE2. In contrast, the expression of the isoenzymes microsomal prostaglandin E synthase-2 (mPGES-2) and cytosolic prostaglandin E synthase (cPGES) was unaffected by TNFα treatment. Using oligonucleotide microarray analysis in a time-course factorial design including time points 1, 3 and 6 h, differentially expressed genes in response to TNFα treatment were identified. Enrichment analysis of microarray data indicated two positively regulated signal transduction pathways: c-Jun N-terminal kinase (JNK) and Nuclear Factor-κB (NF-κB). To evaluate their involvement in the regulation of mPGES-1 and COX-2 expression, we used specific inhibitors as well as phosphorylation analysis. Phosphorylation analysis of JNK (T183/Y185) and NF-κB p65 (S536) showed increased phosphorylation in response to TNFα treatment, which was decreased by specific inhibitors of JNK (SP600125) and NF-κB (Bay 11-7082, Ro 106-9920). Inhibitors of JNK and NF-κB also decreased the TNFα-stimulated up-regulation of mPGES-1 and COX-2 as well as PGE2 production.ConclusionIn the global gene expression profile, the enrichment analysis of microarray data identified the two signal transduction pathways JNK and NF-κB as positively regulated by the cytokine TNFα. Inhibition of these TNFα-activated signal pathways reduced the expression of mPGES-1 and COX-2 as well as their end product PGE2 in gingival fibroblasts. The involvement of the signal pathways JNK and NF-κB in the regulation of PGE2 induced by TNFα may suggest these two pathways as possible attractive targets in the chronic inflammatory disease periodontitis.

Epidermal growth factor potentiates interleukin 1 and tumour necrosis factor-induced prostaglandin biosynthesis in human gingival fibroblasts

Abstract The effects of and interactions between epidermal growth factor (EGF), transforming growth factor α (TGF-α) interleukin 1 (IL-1) and tumour necrosis factor α (TNF-α) on arachidonic acid release and prostaglandin biosynthesis in human gingival fibroblasts were studied. IL-1α, IL-1β and TNF-α, but not EGF nor TGF-α, stimulated prostaglandin E 2 (PGE 2 ) formation in the gingival fibroblasts. The effect of IL-1α, IL-1β and TNF-α on PGE 2 formation was significantly potentiated by EGF in a dose-dependent manner. Similary, TGF-α synergistically potentiated IL-1β stimulated PGE 2 formation. IL-1β but not EGF stimulated the release of 3 H-arachidonic acid ( 3 H-AA) from prelabelled gingival fibroblasts. In contrast to the effect on PGE 2 formation, no synergistic interaction between EGF and IL-1 was seen on arachidonic acid (AA) release. Addition of unlabelled exogenous AA, in the presence of EGF, resulted in a significant increase in PGE 2 formation compared to that seen in fibroblasts not exposed to EGF. The results demonstrate that EGF and IL-1 as well as EGF and TNF-α act in concert to enhance prostanoid formation in gingival fibroblasts. Data indicates that EGF potentiates the IL-1 and TNF-α induced PGE 2 formation at the level of prostaglandin endoperoxide synthase (cyclooxygenase). The synergistic effects of inflammatory cytokines and growth factors may be of physiological importance for regulation of regenerative tissue growth during inflammation and repair.

Gene Expression Profiles in Paired Gingival Biopsies from Periodontitis-Affected and Healthy Tissues Revealed by Massively Parallel Sequencing

Periodontitis is a chronic inflammatory disease affecting the soft tissue and bone that surrounds the teeth. Despite extensive research, distinctive genes responsible for the disease have not been identified. The objective of this study was to elucidate transcriptome changes in periodontitis, by investigating gene expression profiles in gingival tissue obtained from periodontitis-affected and healthy gingiva from the same patient, using RNA-sequencing. Gingival biopsies were obtained from a disease-affected and a healthy site from each of 10 individuals diagnosed with periodontitis. Enrichment analysis performed among uniquely expressed genes for the periodontitis-affected and healthy tissues revealed several regulated pathways indicative of inflammation for the periodontitis-affected condition. Hierarchical clustering of the sequenced biopsies demonstrated clustering according to the degree of inflammation, as observed histologically in the biopsies, rather than clustering at the individual level. Among the top 50 upregulated genes in periodontitis-affected tissues, we investigated two genes which have not previously been demonstrated to be involved in periodontitis. These included interferon regulatory factor 4 and chemokine (C-C motif) ligand 18, which were also expressed at the protein level in gingival biopsies from patients with periodontitis. In conclusion, this study provides a first step towards a quantitative comprehensive insight into the transcriptome changes in periodontitis. We demonstrate for the first time site-specific local variation in gene expression profiles of periodontitis-affected and healthy tissues obtained from patients with periodontitis, using RNA-seq. Further, we have identified novel genes expressed in periodontitis tissues, which may constitute potential therapeutic targets for future treatment strategies of periodontitis.