Macrophages Play a Key Role in the Obesity‐Induced Periodontal Innate Immune Dysfunction via Nucleotide‐Binding Oligomerization Domain‐Like Receptor Protein 3 Pathway

Background: Obesity is associated with infiltration of macrophages into adipose tissue. However, effects of obesity on macrophage infiltration and activation in periodontal tissues with periodontitis are still to be elucidated. Methods: A diet‐induced obesity 16‐week mouse model was constructed, and periodontitis was induced by periodontal ligation for 10 days. The model consisted of periodontitis (P) and control (C) groups, with high fat (HF) and normal (N) diet conditions. Bone loss (BL) was analyzed by microcomputed tomography. In periodontal tissues, immunohistochemical staining and quantitative polymerase chain reaction (qPCR) detected expressions of: 1) nucleotide‐binding oligomerization domain‐like receptor protein 3 (NLRP3) pathway; 2) macrophage‐specific marker (F4/80); and 3) macrophage chemotactic protein 1 (MCP1). Bone marrow‐derived macrophages (BMDMs) from the mouse model were stimulated by Porphyromonas gingivalis lipopolysaccharide (LPS) in vitro (NC/NC + LPS: BMDMs from NC group without/with LPS stimulation; HFC/HFC + LPS: BMDMs from HFC group without/with LPS stimulation). Expressions of NLRP3 pathway in BMDMs were detected by immunocytochemical staining and qPCR. Results: BL increased significantly with periodontitis (NC versus NP; HFC versus HFP) and obesity (NP versus HFP). Expressions of NLRP3 pathway were significantly elevated in gingival tissues with periodontitis (NC versus NP; HFC versus HFP), but not with obesity (NC versus HFC; NP versus HFP). F4/80 and MCP1 expressions were significantly upregulated in gingival tissues with periodontitis (NC versus NP; HFC versus HFP) but significantly downregulated in the context of obesity (NP versus HFP). In vitro, NLRP3 pathway expressions were significantly upregulated in BMDMs after LPS stimulation (NC + LPS versus NC; HFC + LPS versus HFC), but significantly downregulated in HFC groups (HFC versus NC; HFC + LPS versus NC + LPS). Conclusion: Obesity may paralyze innate immune response of periodontium via attenuating infiltration and activation of macrophages and further aggravate periodontal disease.     

Chemerin as a Novel Crevicular Fluid Marker of Patients With Periodontitis and Type 2 Diabetes Mellitus

Background: The objectives of the present study are to: 1) determine whether gingival crevicular fluid (GCF) chemerin is a novel predictive marker for patients with chronic periodontitis (CP) with and without type 2 diabetes mellitus (t2DM); 2) analyze the relationship between chemerin and interleukin (IL)‐6 in periodontally healthy individuals and in patients with CP and with and without t2DM; and 3) evaluate the effect of non‐surgical periodontal therapy on GCF chemerin levels. Methods: Eighty individuals were split into four groups: 20 who were systemically and periodontally healthy (CTRL), 20 with t2DM and periodontally healthy (DM‐CTRL), 20 systemically healthy with CP (CP), and 20 with CP and t2DM (DM‐CP). Individuals with periodontitis were treated with non‐surgical periodontal therapy. GCF sampling procedures and clinical periodontal measures were performed before and 6 weeks after treatment. Enzyme‐linked immunosorbent assay was used to measure chemerin and IL‐6 levels. Results: Greater values for GCF chemerin and IL‐6 levels were found in CP groups than in periodontally healthy groups, in DM‐CP than in CP, and in DM‐CTRL than in CTRL (P <0.008). GCF chemerin and IL‐6 levels decreased following therapy in CP groups (P <0.02). A comprehensive overview of all groups showed a statistically significant positive correlation of chemerin with IL‐6, glycated hemoglobin, sampled‐site clinical attachment level, and gingival index (P <0.05). Conclusions: In this study, periodontitis and t2DM induced aberrant secretion of chemerin, and non‐surgical periodontal therapy influenced the decrease of GCF chemerin levels in patients with CP with and without t2DM. Furthermore, it suggests GCF chemerin levels may be considered a potential proinflammatory marker for diabetes, periodontal disease, and treatment outcomes.     

MicroRNA‐126 Regulates Inflammatory Cytokine Secretion in Human Gingival Fibroblasts Under High Glucose via Targeting Tumor Necrosis Factor Receptor Associated Factor 6

Background: MicroRNAs (miRs) play a crucial role in inflammatory diseases, including periodontitis. Meanwhile, miRs act as biomarkers for predicting diabetes mellitus (DM). However, the regulatory mechanism of miR‐126 on development of periodontitis in patients with DM still remains unclear. Methods: Human gingival fibroblasts were cultured with low (5.5 mmol/L), medium (15 mmol/L), and high (25 mmol/L) glucose, respectively. Expressions of miR‐126, tumor necrosis factor (TNF) receptor associated factor (TRAF) 6, and related cytokines were analyzed by real‐time polymerase chain reaction (PCR). After transfection with miR‐126 mimic, PCR and western blot were performed to detect level of TRAF6, and luciferase reporter assay confirmed if TRAF6 is the direct target of miR‐126. Production of cytokines was measured using enzyme‐linked immunosorbent assay. Results: Increased glucose significantly suppressed miR‐126 expression in human gingival fibroblasts (P <0.05). Also, high glucose increased TRAF6, interleukin (IL)‐6, TNF‐α, and chemical chemokine ligand (CCL) 2 levels, whereas it decreased IL‐10 level. MiR‐126 mimic significantly decreased TRAF6 mRNA and protein levels under high glucose (P <0.05). Also, miR‐126 directly targeted TRAF6 through binding to its 3′ untranslated region in human gingival fibroblasts. Overexpression of miR‐126 significantly abrogated high glucose–induced secretion of proinflammatory cytokines such as IL‐6, TNF‐α, and CCL2 and promoted production of IL‐10. Conclusion: These data suggest that miR‐126 inhibits inflammation of human gingival fibroblasts under high glucose through targeting TRAF6, which may be a potential therapeutic target for periodontitis concomitant with DM.     

Expression of Leptin and Visfatin in Gingival Tissues of Chronic Periodontitis With and Without Type 2 Diabetes Mellitus: A Study Using Enzyme‐Linked Immunosorbent Assay and Real‐Time Polymerase Chain Reaction

Background: The aim of this study is to investigate the protein and gene expression of leptin and visfatin in gingival tissue from patients with chronic periodontitis (CP), patients with CP and type 2 diabetes mellitus (T2DM), and healthy individuals. Methods: The study includes 50 individuals: 10 healthy individuals, 20 patients with CP, and 20 patients with CP and T2DM. Plaque index, gingival index, probing depth, and clinical attachment loss were measured, and gingival biopsies were obtained. Leptin and visfatin protein expression in gingival tissues was determined using enzyme‐linked immunosorbent assay, and messenger RNA (mRNA) expression was measured via real‐time polymerase chain reaction. Results: The highest leptin mRNA and protein expression was observed in the control group and was significantly (P ≤0.05) different from the CP and CP+T2DM groups. Gingival tissues from patients with CP and T2DM had a significant increase in visfatin and a decrease in leptin gene and protein expression (P <0.05) compared with both controls and patients with CP. Conclusion: Expression of leptin and visfatin in the gingival tissues suggests a possible role for these adipokines in the pathogenesis of CP and T2DM.     

Increased Expression of Interleukin (IL)‐35 and IL‐17, But Not IL‐27, in Gingival Tissues With Chronic Periodontitis

Background: Interleukin (IL)‐35 plays an important role in immune regulation through the suppression of effector T‐cell populations, including T‐helper 17 (Th17) cells. Although Th17 cells and IL‐17 are involved in the pathogenesis of periodontitis, the level of IL‐35 in inflamed periodontal tissues is unclear. Here, IL‐35, IL‐17, and IL‐27 production/expression in gingival crevicular fluid (GCF) and human gingival tissue were investigated. Methods: GCF samples were collected from buccal (mesial, center, and distal) sites of teeth from patients with chronic periodontitis (CP) and healthy controls and were analyzed by enzyme‐linked immunosorbent assay for IL‐35 (periodontitis, n = 36; healthy, n = 30) and IL‐17 (periodontitis, n = 16; healthy, n = 13). Gingival tissue, including sulcus/pocket epithelium and underlying connective tissue, was collected from an additional 10 healthy participants and 10 patients with CP and were analyzed by quantitative polymerase chain reaction (qPCR) for Epstein Barr virus‐induced gene 3 (EBI3), IL12A, and IL17A. IL27p28 was also tested by qPCR. Results: IL‐35 and IL‐17 were significantly higher in GCF from patients with periodontitis than healthy participants (P <0.01, P <0.05, respectively). In both healthy participants and those with periodontitis, positive correlations were found among IL‐35 and probing depth and clinical attachment level (CAL) as well as between IL‐17 and CAL. EBI3, IL12A (components of IL‐35), and IL17A messenger RNA expression levels were significantly higher in inflamed gingival tissue than in healthy control tissues (P <0.05). IL27p28 was not detected in any sample, suggesting that IL‐27 is not produced in large quantities in periodontal tissue. Conclusion: IL‐35 and IL‐17, but not IL‐27, may play important roles in the pathogenesis of periodontitis.     

Level of Interleukin‐35 in Gingival Crevicular Fluid,Saliva, and Plasma in Periodontal Disease and Health

Background: A novel member of the interleukin (IL)‐12 family, IL‐35 is an important inhibitory cytokine released by regulatory T cells. The aim of this study is to evaluate gingival crevicular fluid (GCF), saliva, and plasma levels of IL‐35 in periodontal disease and health. Methods: Samples of GCF, whole saliva, and plasma were obtained from systemically healthy, non‐smoking individuals with gingivitis (n = 20) or chronic periodontitis (CP) (n = 20) and periodontally healthy individuals (n = 20). Full‐mouth clinical periodontal measurements, including probing depth (PD), bleeding on probing, gingival index, and plaque index (PI), were also recorded. Enzyme‐linked immunosorbent assay was used to determine IL‐35 levels in the samples. Data were tested statistically by analysis of variance and Pearson rank correlation test. Results: All clinical parameters were significantly higher in the CP group than the healthy and gingivitis groups (P <0.001). The GCF total amount of IL‐35 was significantly higher in the CP group than the other groups (P = 0.04), whereas the GCF concentration of IL‐35 was significantly higher in the healthy group than the other groups (P = 0.002). There were significant differences among the study groups in terms of salivary IL‐35 level (P <0.001), with the highest level observed in the healthy group and the lowest in the CP group. There was no statistical difference between groups in plasma levels of IL‐35 (P >0.05). There was a positive correlation between GCF total amount of IL‐35 and PD (r = 0.338, P = 0.03) and PI (r = 0.374, P = 0.005) parameters. Conclusions: IL‐35 could have an important role in suppressing periodontal inflammation and maintaining periodontal health. Additional studies are required to evaluate its role in periodontal diseases.     

Saliva and Serum Levels of Pentraxin‐3 and Interleukin‐1β in Generalized Aggressive or Chronic Periodontitis

Background: Pentraxin‐3 (PTX3) is a multifactorial protein involved in immunity and inflammation, which is rapidly produced and released by several cell types in response to inflammatory signals. The aim of the present study is to evaluate saliva, serum levels of PTX3, interleukin (IL)‐1β in patients with generalized chronic periodontitis (CP) or aggressive periodontitis (AgP), and periodontally healthy individuals. Methods: A total of 94 participants (25 patients with AgP, 25 patients with CP, and 44 periodontally healthy individuals matched with AgP and CP groups) were recruited. Saliva and serum samples were collected. Clinical periodontal measurements were recorded. PTX3, IL‐1β levels in serum, and saliva samples were determined by enzyme‐linked immunosorbent assay. Data were tested statistically using Kruskal‐Wallis, Mann‐Whitney U, and Spearman ρ rank test. Results: Serum and saliva data were similar in CP and AgP groups. Saliva levels of IL‐1β were significantly higher in the AgP and CP groups than controls (P <0.05). Salivary PTX3 levels were similar in the CP and control groups. Significantly higher salivary concentrations of PTX3 were detected in the AgP group than the control group (P <0.05). Saliva PTX3 levels correlated with plaque index and bleeding on probing in the CP group (P <0.05). Serum and saliva PTX3 levels correlated with those of IL‐1β in the AgP group (P <0.05). Conclusions: It may be suggested that PTX3 is related with periodontal tissue inflammation. Its salivary concentrations may have a diagnostic potential. Additional intervention and follow‐up studies coupling PTX3 concentrations with microbiologic analysis would better clarify its role in periodontal diseases.     

Irsogladine maleate regulates epithelial barrier function in tumor necrosis factor-α-stimulated human gingival epithelial cells

Fujita T, Yumoto H, Shiba H, Ouhara K, Miyagawa T, Nagahara T, Matsuda S, Kawaguchi H, Matsuo T, Murakami S, Kurihara H. Irsogladine maleate regulates epithelial barrier function in tumor necrosis factor‐α‐stimulated human gingival epithelial cells. J Periodont Res 2012; 47: 55–61. © 2011 John Wiley & Sons A/S Background and Objective: As epithelial cells function as a mechanical barrier, the permeability of the gingival epithelial cell layer indicates a defensive capability against invasion by periodontal pathogens. We have reported the expression of claudin‐1 and E‐cadherin, key regulators of permeability, in the gingival junctional epithelium. Irsogladine maleate (IM) is a medication for gastric ulcers and also regulates Aggregatibacter actinomycetemcomitans‐stimuated chemokine secretion and E‐cadherin expression in gingival epithelium. In this study, we have further investigated the effects of IM on the barrier functions of gingival epithelial cells under inflammatory conditions. Material and methods: We examined the permeability, and the expression of claudin‐1 and E‐cadherin, in human gingival epithelial cells (HGECs) stimulated with tumor necrosis factor (TNF)‐α, with or without IM. Results: TNF‐α increased the permeability of HGECs, and IM abolished the increase. TNF‐α reduced the expression of E‐cadherin in HGECs, and IM reversed the reduction. In addition, immunofluorescence staining showed that TNF‐α disrupted claudin‐1 expression in HGECs, and IM reversed this effect. Conclusion: The results suggest that IM reverses the TNF‐α‐induced disruption of the gingival epithelial barrier by regulating E‐cadherin and claudin‐1.     

Salivary Levels of NLRP3 Inflammasome‐Related Proteins as Potential Biomarkers of Periodontal Clinical Status

Background: Emerging evidence suggests that activation of inflammasomes plays a central mechanism in pathogenesis of periodontitis. This study aims to compare salivary levels of nod‐like receptor family pyrin domain containing protein (NLRP) 3, apoptosis‐associated speck‐like protein containing a caspase recruitment domain (ASC), cysteine aspartase (caspase)‐1, and interleukin (IL)‐1β from individuals with aggressive (AgP) or chronic periodontitis (CP) and healthy controls (HC), as well as elucidate its association with periodontal clinical status. Methods: Saliva samples from individuals with CP (n = 75), AgP (n = 20), and HC (n = 69) were collected. Periodontal status was assessed by measurement of probing depth, clinical attachment level, and extent and severity of disease. Salivary levels of analytes were analyzed by enzyme‐linked immunosorbent assay. Association between biomarkers with CP or AgP was analyzed using multivariate binary logistic regression models. Results: Significantly higher levels of NLRP3, ASC, and IL‐1β were detected in periodontitis groups in comparison to the periodontally HC group. However, no significant differences were observed for caspase‐1 levels between clinical groups, and only NLRP3 salivary concentration was significantly higher in AgP compared with CP patients. Also, positive significant correlations among NLRP3, ASC, and IL‐1β salivary concentrations and clinical parameters were observed. Logistic regression analyses revealed a strong/independent association of NLRP3, ASC, and IL‐1β salivary levels with CP and AgP. Conclusion: Although the concentration of caspase‐1 in saliva samples makes its determination useless for detection of periodontal disease and/or its severity, salivary levels of NLRP3, ASC, and IL‐1β may act as strong/independent indicators of amount and extent of periodontal breakdown in both CP and AgP and could potentially be used for prevention and therapy of this group of diseases.     

Activation of inflammasomes in dendritic cells and macrophages by Mycoplasma salivarium

Interleukin‐1β (IL‐1β) plays crucial roles in the pathogenesis of periodontal disease. It is produced after the processing of pro‐IL‐1β by caspase‐1, which is activated by the inflammasome‐a multiprotein complex comprising nucleotide‐binding domain leucine‐rich repeat‐containing receptor (NLR), the adaptor protein apoptosis‐associated speck‐like protein containing a caspase‐recruitment domain (ASC), and procaspase‐1. Mycoplasma salivarium preferentially inhabits the gingival sulcus and the incidence and number of organisms in the oral cavity increase significantly with the progression of periodontal disease. To initially clarify the association of this organism with periodontal diseases, this study determined whether it induces IL‐1β production by innate immune cells such as dendritic cells or macrophages by using Mycoplasma pneumoniae as a positive control. Both live and heat‐killed M. salivarium and M. pneumoniae cells induced IL‐1β production by XS106 murine dendritic cells as well as pyroptosis. The activities were significantly downregulated by silencing of caspase‐1. Bone‐marrow‐derived macrophage (BMMs) from wild‐type and NLR‐containing protein 3 (NLRP3)‐, ASC‐, and caspase‐1‐deficient mice were examined for IL‐1β production in response to these mycoplasmas. Live M. salivarium and M. pneumoniae cells almost completely lost the ability to induce IL‐1β production by BMMs from ASC‐ and caspase‐1–deficient mice. Their activities toward BMMs from NLRP3‐deficient mice were significantly but not completely attenuated. These results suggest that live M. salivarium and M. pneumoniae cells can activate several types of inflammasomes including the NLRP3 inflammasome. Both M. salivarium and M. pneumoniae cells can activate THP‐1 human monocytic cells to induce IL‐1β production. Hence, the present finding that M. salivarium induces IL‐1β production by dendritic cells and macrophages may suggest the association of this organism with periodontal diseases.     

Resistin Levels in Gingival Crevicular Fluid of Patients With Chronic Periodontitis and Type 2 Diabetes Mellitus

Background: Resistin is associated with local and systemic inflammatory conditions with a direct correlation with type 2 diabetes mellitus (T2DM). The aim of this clinico‐biochemical study is to estimate and compare the levels of resistin in the gingival crevicular fluid (GCF) in health, chronic periodontitis (CP), and T2DM. Methods: Sixty patients (aged >35 years) who participated in this study were divided into four groups of 15 patients each: healthy individuals (group 1), patients with CP (group 2), patients with T2DM (group 3), and patients with T2DM and CP (group 4). The parameters assessed included plaque index (PI), gingival index (GI), probing depth (PD), periodontal index, body mass index, random blood sugar (RBS), and glycated hemoglobin (HbA1c). GCF (4 μL) was collected and analyzed for resistin levels using an enzyme‐linked immunosorbent assay. Results: Resistin was detected in the GCF of all patients. A significant difference was observed in GCF resistin concentrations from group 1 versus group 2 (P = 0.0093), group 3 (P = 0.0341), and group 4 (P = 0.0002); in group 2 versus group 4 (P = 0.0032); and in group 3 versus group 4 (P = 0.0008). When all the samples were analyzed together, GCF resistin levels positively correlated with GI, PD, PI, RBS, and HbA1c and were predictable with PD and HbA1c. Conclusions: Resistin levels are increased in CP and T2DM. Hence, GCF resistin levels may be considered as a potential inflammatory marker for periodontitis with T2DM.     

Analysis of YKL‐40 Acute‐Phase Protein and Interleukin‐6 Levels in Periodontal Disease

Background: YKL‐40, a new acute‐phase protein, is shown to be elevated in inflammatory diseases, such as rheumatoid arthritis, type 2 diabetes mellitus, and coronary artery diseases. However, there is no data indicating a relationship between YKL‐40 and periodontal disease. Interleukin‐6 (IL‐6) is the major regulator of acute‐phase protein synthesis and one of the most studied inflammatory markers in periodontal disease. The purpose of the present study is to evaluate YKL‐40 and IL‐6 levels in gingival crevicular fluid (GCF) and serum of patients with periodontal disease and healthy individuals. Methods: Periodontally healthy individuals (n = 15), patients with gingivitis (n = 15), and patients with severe chronic periodontitis (CP) (n = 15) without any systemic disease were included in the study. Clinical measurements were recorded; GCF and blood samples were obtained from each participant. GCF and serum YKL‐40 and IL‐6 levels were analyzed by enzyme‐linked immunosorbent assay. Statistical analysis was performed by parametric and non‐parametric tests. Results: Total amounts of YKL‐40 and IL‐6 in GCF as well as serum YKL‐40 and IL‐6 levels were significantly higher in patients with gingivitis and CP compared with healthy controls (P <0.01). YKL‐40 levels in GCF and serum as well as serum IL‐6 levels were significantly higher in patients with CP compared with patients with gingivitis (P <0.01). Conclusions: YKL‐40 levels in GCF as well as serum YKL‐40 and IL‐6 levels increased from gingivitis to periodontitis. Within the limits of the present study, the YKL‐40 molecule might be a potential novel inflammatory marker of periodontal disease.     

The Influence of Glycated Hemoglobin on the Cross Susceptibility Between Type 1 Diabetes Mellitus and Periodontal Disease

Background: Periodontal disease is a major complication of type 1 diabetes mellitus (T1DM). The aim of the present study is to investigate the relationship between glycated hemoglobin and circulating levels of interleukin (IL)‐6, IL‐8, and C‐X‐C motif chemokine ligand 5 (CXCL5) in non‐smoking patients suffering from T1DM, with and without periodontitis. In addition, to determine the effect of advanced glycation end products (AGE) in the presence and absence of Porphyromonas gingivalis lipopolysaccharide (LPS) on IL‐6, IL‐8, and CXCL5 expression by THP‐1 monocytes and OKF6/TERT‐2 cells. Methods: There were 104 participants in the study: 19 healthy volunteers, 23 patients with periodontitis, 28 patients with T1DM, and 34 patients with T1DM and periodontitis. Levels of blood glucose/glycated hemoglobin (International Federation of Clinical Chemistry [IFCC]) were determined by high‐performance liquid chromatography. Levels of IL‐6, IL‐8, and CXCL5 in plasma were determined by enzyme‐linked immunosorbent assay (ELISA). In vitro stimulation of OKF6/TERT‐2 cells and THP‐1 monocytes was performed with combinations of AGE and P. gingivalis LPS. Changes in expression of IL‐6, IL‐8, and CXCL5 were monitored by ELISA and real‐time polymerase chain reaction. Results: Patients with diabetes and periodontitis had higher plasma levels of IL‐8 than patients with periodontitis alone. Plasma levels of IL‐8 correlated significantly with IFCC units, clinical probing depth, and attachment loss. AGE and LPS, alone or in combination, stimulated IL‐6, IL‐8, and CXCL5 expression in both OKF6/TERT‐2 cells and THP‐1 monocytes. Conclusions: Elevated plasma levels of IL‐8 potentially contribute to the cross‐susceptibility between periodontitis and T1DM. P. gingivalis LPS and AGE in combination caused significantly greater expression of IL‐6, IL‐8, and CXCL5 from THP‐1 monocytes and OKF6/TERT‐2 cells than LPS alone.     

Diabetes mellitus-associated periodontitis: differences between type 1 and type 2 diabetes mellitus

Aspriello SD, Zizzi A, Tirabassi G, Buldreghini E, Biscotti T, Faloia E, Stramazzotti D, Boscaro M, Piemontese M. Diabetes mellitus‐associated periodontitis: differences between type 1 and type 2 diabetes mellitus. J Periodont Res 2011; 46: 164–169. © 2010 John Wiley & Sons A/S Background and Objective: Although many studies have appeared about diabetes mellitus‐associated periodontitis, few have compared periodontitis inflammatory markers between type 1 (T1DM) and type 2 diabetes mellitus (T2DM), and information regarding this issue is scarce and contradictory. We evaluated the levels of plasma C‐reactive protein and of interleukin‐1β (IL‐1β), interleukin‐6 (IL‐6) and tumour necrosis factor‐α (TNF‐α) in gingival crevicular fluid in two groups of subjects affected by T1DM and T2DM, in order to identify possible differences between the two classes in the inflammatory mechanisms of diabetes mellitus‐associated periodontitis. Material and Methods: Plasma C‐reactive protein and gingival crevicular fluidIL‐1β, IL‐6 and TNF‐α were measured in periodontitis patients affected by type 1 (P‐T1DM, n = 24) and type 2 diabetes mellitus (P‐T2DM, n = 24). Results: Gingival crevicular fluid levels of IL‐1β and TNF‐α in P‐T1DM subjects were significantly higher than in P‐T2DM subjects. In P‐T1DM subjects, we found significant negative correlations between the duration of diabetes mellitus and IL‐1β and between the duration of diabetes mellitus and TNF‐α. Conclusion: This study shows that IL‐1β and TNF‐α levels in periodontitis patients with T1DM are affected by the duration of diabetes mellitus.     

Retinoic acid‐inducible gene‐I is induced in gingival fibroblasts by lipopolysaccharide or poly IC: possible roles in interleukin‐1β, ‐6 and ‐8 expression

Retinoic acid‐inducible gene‐I (RIG‐I) is a member of the DExH family of proteins, and little is known of its biological function in the oral region. We previously reported that interleukin 1β (IL‐1β) induced RIG‐I expression in gingival fibroblasts. In this study, we studied the mechanism of RIG‐I expression induced by lipopolysaccharide (LPS) or double‐stranded RNA (dsRNA) in gingival fibroblasts. We also addressed the role of RIG‐I in the expression of IL‐1β, IL‐6 and IL‐8 in gingival fibroblasts stimulated with LPS or dsRNA. We stimulated cultured human gingival fibroblasts with LPS or dsRNA, and examined the expression of RIG‐I mRNA and protein. The effect of cycloheximide, a protein synthesis inhibitor, on RIG‐I induction by these stimuli was examined. The expression of IL‐1β, IL‐6 and IL‐8 in gingival fibroblasts transfected with RIG‐I cDNA stimulated with LPS or dsRNA was examined. LPS or dsRNA induced the expression of mRNA and protein for RIG‐I in concentration‐ and time‐dependent manners. We also examined the localization of RIG‐I, and found that it was expressed in cytoplasm. Cycloheximide did not suppress the LPS or dsRNA‐induced RIG‐I expression. Introduction of RIG‐I cDNA into gingival fibroblasts resulted in enhanced expression of IL‐1β, IL‐6 and IL‐8; moreover, overexpression of RIG‐I stimulated with LPS or dsRNA synergistically increased expression of IL‐1β, IL‐6 and IL‐8. RIG‐I may have important roles in the innate immune response in the regulation of IL‐1β, IL‐6 and IL‐8 expression in gingival fibroblasts in response to LPS and dsRNA.     

热刺激对人牙周膜细胞NLRP3/Caspase-1信号通路调控影响的初步探索

目的    初步探索热刺激状态下，正常及炎症人牙周膜细胞（PDLCs）内NOD样受体蛋白3（NLRP3）/半胱天冬酶1（Caspase-1）信号通路的调控表达变化。方法    使用三磷酸腺苷（ATP）和脂多糖（LPS）制备炎症PDLCs模型，分别以45℃、5%CO2条件和37℃、5%CO2条件培养正常和炎症PDLCs，CCK8法检测细胞光密度（OD450）值。根据细胞刺激条件，分为3个实验组（ATP+LPS组、热刺激组、ATP+LPS+热刺激组）和1个对照组，采用荧光实时定量PCR（qRT-PCR）检测各组热休克RNA-1（HSR1）、热休克转录因子1（HSF-1）、NLRP3、Caspase-1、白介素（IL）-1β、IL-18的表达水平。结果    ①正常PDLCs活性检测结果显示，随着培养时间的延长，37℃培养条件下细胞OD450值逐渐增加，45℃培养条件下细胞OD450值逐渐降低（F = 36.309，P < 0.05）；炎症PDLCs活性检测结果显示，随着培养时间的延长，2种温度培养条件下细胞OD450值均逐渐降低（F = 23.353，P < 0.05）；且不同培养时间的2种温度培养条件下细胞OD450值比较，差异均有统计学意义（均P < 0.05）；随着培养时间的延长此差异越明显（均P < 0.05）。②各组测量指标mRNA相对表达量总的比较，差异均有统计学意义（均P < 0.05）。3个实验组各测量指标mRNA相对表达量分别与对照组比较，差异均有统计学意义（均P < 0.05）。且与ATP+LPS组比较，热刺激组和ATP+LPS+热刺激组的HSR1和HSF-1 mRNA相对表达量增高，NLRP3、Caspase-1、IL-1β、IL-18 mRNA相对表达量降低，差异均有统计学意义（均P < 0.05）。结论    HSR1可能负反馈调节着NLRP3/Caspase-1炎症小体通路，正常和炎症PDLCs抵抗热刺激时的免疫防御反应能力均减弱。     

Nitric oxide inhibits androgen receptor-mediated collagen production in human gingival fibroblasts

Lin S‐J, Lu H‐K, Lee H‐W, Chen Y‐C, Li C‐L, Wang L‐F. Nitric oxide inhibits androgen receptor‐mediated collagen production in human gingival fibroblasts. J Periodont Res 2012; 47: 701–710. © 2012 John Wiley & Sons A/S Background and Objective: In our previous study, we found that flutamide [an androgen receptor (AR) antagonist] inhibited the up‐regulation of collagen induced by interleukin (IL)‐1β and/or nifedipine in gingival fibroblasts. The present study attempted to verify the role of nitric oxide (NO) in the IL‐1β/nifedipine‐AR pathway in gingival overgrowth. Material and Methods: Confluent gingival fibroblasts derived from healthy individuals (n = 4) and those with dihydropyridine‐induced gingival overgrowth (DIGO) (n = 6) were stimulated for 48 h with IL‐1β (10 ng/mL), nifedipine (0.34 μm ) or IL‐1β + nifedipine. Gene and protein expression were analyzed with real‐time RT‐PCR and western blot analyses, respectively. Meanwhile, Sircol dye‐binding and the Griess reagent were, respectively, used to detect the concentrations of total soluble collagen and nitrite in the medium. Results: IL‐1β and nifedipine simultaneously up‐regulated the expression of the AR and type‐I collagen α1 [Colα1(I)] genes and the total collagen concentration in DIGO cells (p < 0.05). IL‐1β strongly increased the expression of inducible nitric oxide synthase (iNOS) mRNA and the nitrite concentration in both healthy and DIGO cells (p < 0.05). However, co‐administration of IL‐1β and nifedipine largely abrogated the expression of iNOS mRNA and the nitrite concentration with the same treatment. Spearman’s correlation coefficients revealed a positive correlation between the AR and total collagen (p < 0.001), but they both showed a negative correlation with iNOS expression and the NO concentration (p < 0.001). The iNOS inhibitor, 1400W, enhanced IL‐1β‐induced AR expression; furthermore, the NO donor, NONOate, diminished the expression of the AR to a similar extent in gingival fibroblasts derived from both healthy patients and DIGO patients (p < 0.05). Conclusion: IL‐1β‐induced NO attenuated AR‐mediated collagen production in human gingival fibroblasts. The iNOS/NO system down‐regulated the axis of AR/Colα1(I) mRNA expression and the production of AR/total collagen proteins by DIGO cells.     

Increased expression of C-reactive protein gene in inflamed gingival tissues could be derived from endothelial cells stimulated with interleukin-6

Background

Epidemiological studies have suggested periodontitis as a risk factor for ischemic heart disease. High sensitive C-reactive protein (hs-CRP), a predictor of cardiovascular risk, is elevated in periodontitis patients. Therefore, local infection-induced elevation of systemic CRP could account for the relationship between the 2 diseases. However, the underlying mechanism of CRP production in the periodontal tissues has not been fully elucidated. Therefore, the aim of the present study was to clarify the mechanism of CRP production in periodontal tissues.

Methods

Gene expression of CRP in gingival biopsies was analysed by quantitative PCR. Human gingival epithelial cells (HGECs), human gingival fibroblasts (HGFBs), and human coronary artery endothelial cells (HCAECs) were characterized for CRP-producing ability by incubating with interleukin (IL)-1β, IL-6, soluble IL-6 receptor (sIL-6R), and Porphyromonas gingivalis strain W83.

Results

Gene expression of CRP is significantly elevated in periodontitis lesions compared with gingivitis lesions. HCAECs, but not HGECs and HGFBs, produced CRP in response to IL-6 and IL-1β in the presence of sIL-6R. In contrast to IL-6, the effect of IL-1β on CRP production was indirect via induction of IL-6. IL-1β was produced by HGECs and HGFBs with stimulation of P. gingivalis antigens.

Conclusion

These results suggest that CRP induced locally by periodontal infection may play another role in the pathogenesis of periodontal disease, and to a much lesser extent, has the potential to modulate systemic CRP level by extra-hepatic CRP production.