A novel IkB kinase inhibitor attenuates ligature-induced periodontal disease in mice.

BACKGROUNDS AND OBJECTIVES: IMD-0354 is a novel I kappa-B kinase (IKK) inhibitor, which regulates inflammation. The purpose of this study was to examine the effect of the reagent on bone loss for ligature-induced periodontitis. MATERIAL AND METHODS: We ligated around the upper right second molars of 8-week-old C57BL/6J mice in the split-mouth model. The test mice were injected intraperitoneally with IMD-0354 before the placement of the ligature. The control mice were injected intraperitoneally with 0.5% carboxymethylcellulose (CMC) as vehicle before the placement of the ligature. To determine the optimum concentration of the reagent on ligature-induced periodontitis in the mice, we examined the effect of three types of concentration, which were 1, 5, and 10 mg/kg of IMD-0354, as a preliminary experiment. After we determined 10 mg/kg as the optimum concentration for the IMD group by micro-CT analysis, both the IMD and CMC groups (n = 15 each in total, including all the analyses) were subdivided into two small groups, respectively, for further analyses: I group (unligated side of IMD group), IL group (ligated side of IMD group), C group (unligated side of CMC group) and CL group (ligated side of CMC group). The mice in the IMD and CMC groups were treated with each reagent daily and sacrificed 8 days after the ligation. For assessment of bone resorption, we performed micro-CT and histological analyses. We also carried out real-time PCR to investigate proinflammatory and bone metabolic markers. RESULTS: There were significant differences for linear bone loss and volumetric parameter in the test (IMD) group compared to the control (CMC) group 8 days after ligation. In terms of the mRNA expression level of gingival tissue, the level of RANKL was significantly suppressed in the IMD group compared to the CMC group. IMD-0354 also tended to suppress the levels of interleukin-1 beta, tumor necrosis factor-alpha, and osteoprotegerin. For histological analysis, the relative numbers of TRAP-positive multinucleated cells decreased significantly in the IMD group compared to the CMC group. CONCLUSION: IMD-0354 regulated bone resorption by ligature-induced periodontitis, and it is suggested that the inhibition of IKK via down-regulation of NF kappa-B may provide periodontal patients with an effective approach to prevent or suppress the disease.

Increased Heart Failure Prevalence in Patients with a High Antibody Level Against Periodontal Pathogen.

The aim of this study was to assess whether a specific cardiovascular disease was related to an increased antibody level against a periodontal pathogen.A strong association between cardiovascular disease and periodontitis was shown, however, the causal relationship was not proven. Increased inflammatory reaction of patients with periodontitis was a possible factor, which connected periodontal infection and vascular diseases.We assessed medical history, blood data, and periodontal conditions in patients with cardiovascular diseases. Serum IgG antibody titers against major periodontal pathogens and existence of salivary periodontal bacteria were analyzed.In total, 348 subjects were enrolled in this study. The patients who exhibited 10,000 counts/mL or more of salivary Porphyromonas gingivalis were divided into two groups according to the antibody level of the pathogen. Patients with a high antibody level against Porphyromonas gingivalis exhibited a high rate of heart failure compared to the low antibody group. Mean probing pocket depth and clinical attachment level significantly increased in the high antibody group. We found that the high anti-Porphyromonas gingivalis antibody group also experienced enhanced antibody levels against other periodontal bacteria.An increased heart failure prevalence was found in patients with a high antibody level against a major periodontal pathogen, Porphyromonas gingivalis.

Porphyromonas Gingivalis Elevated High-Mobility Group Box 1 Levels After Myocardial Infarction in Mice.

High mobility group box 1 (HMGB1) is a nuclear protein released from necrotic cells, inducing inflammatory responses. Epidemiological studies suggested a possible association between periodontitis and cardiovascular diseases (CVDs). Due to tissue damage and necrosis of cardiac cells following myocardial infarction (MI), HMGB1 is released, activating an inflammatory reaction. However, it remains unclear whether periodontitis is also involved in myocardial damage. The purpose of this study was to determine the effect of the periodontal pathogen Porphyromonas gingivalis (P.g.) after MI in mice.C57BL/6J wild type mice in post-MI were inoculated with P.g. in the infected group (P.g.-inoculated MI group) and with phosphate buffer saline (PBS) in the control group (PBS-injected MI group). Plasma samples and twelve tissue samples from mice hearts after MI were obtained. We determined the expression of HMGB1 by ELISA and immunohistochemistry.The level of HMGB1 protein in the P.g.-inoculated MI group was significantly higher than in the PBS-injected MI group on day 5, but not on day 14. Immunohistochemistry analysis revealed that HMGB1 was mainly expressed in cardiomyocytes, immune cells, and vascular endothelial cells in the PBS-injected MI group, while HMGB1 was seen broadly in degenerated cardiomyocytes, extracellular fields, immune cells, and vascular endothelial cells in the P.g.-inoculated MI group. A significant increase in the number of HMGB1 positive cells was observed in the P.g.-inoculated MI group compared to the PBS-injected MI group.Infection with P.g. after MI enhanced myocardial HMGB1 expression. There is a possible relationship between periodontitis and post-infarction myocardial inflammation through HMGB-1.

Overexpression of PD-L1 in gingival basal keratinocytes reduces periodontal inflammation in a ligature-induced periodontitis model.

BACKGROUND: The immune checkpoint programmed cell death 1 (PD-1): PD-1 ligand 1 (PD-L1) pathway plays a crucial role in maintaining immune tolerance and preventing tissue damages by excessive immune responses. PD-L1 is physiologically expressed and upregulated in keratinocytes (KCs) in the oral cavity. We here investigated the contribution of PD-L1 that was overexpressed in gingival basal KCs in a ligature-induced periodontitis model. METHODS: Wild-type (WT) BALB/c and K14/PD-L1 transgenic (tg) mice, in which PD-L1 was overexpressed in basal KCs under control of the keratin 14 promoter, were used. To induce periodontitis, a 9-0 silk ligature was placed around the upper right second molar, and lipopolysaccharide from Porphyromonas gingivalis was applied on the suture. Gingival tissues were collected on day 7, after which histological analyses were performed, including by hematoxylin and eosin and tartrate-resistant acid phosphate staining (TRAP) and quantitative PCR for proinflammatory cytokines and bone metabolism-related genes. Alveolar bone loss at 7 weeks after ligature placement was assessed by micro-computed tomography analysis. RESULTS: PD-L1 was overexpressed in the basal KCs of all gingival epithelia in K14/PD-L1tg mice. Early ligature-induced periodontal inflammation, as assessed based on histological changes, elevation of proinflammatory cytokine (IL-1ß, IL-6, TNF-α) expression, periodontal ligament degeneration, and osteoclastogenesis as assessed by Rankl and Opg expression and TRAP+ cells, was markedly impaired in K14/PD-L1tg mice. Alveolar bone resorption at a late time point was also clearly minimized in K14/PD-L1tg mice. CONCLUSION: Overexpression of PD-L1 in gingival basal keratinocytes in K14/PD-L1tg mice reduces periodontal inflammation and alveolar bone resorption in a ligature-induced periodontitis model.

Accelerated inflammation in peripheral artery disease patients with periodontitis.

PURPOSE: Peripheral artery disease (PAD) is a form of arteriosclerosis that occurs in the extremities and involves ischemia. Previous studies have reported that patients with periodontitis are at high risk for PAD. However, the relationship between these 2 diseases has not yet been fully elucidated. In this cross-sectional study, we investigated this relationship by comparing patients with PAD to those with arrhythmia (ARR) as a control group. METHODS: A large-scale survey was conducted of patients with cardiovascular disease who visited Tokyo Medical and Dental University Hospital. We investigated their oral condition and dental clinical measurements, including probing pocket depth, bleeding on probing, clinical attachment level, and number of missing teeth; we also collected salivary and subgingival plaque samples and peripheral blood samples. All patients with PAD were extracted from the whole population (n=25), and a matching number of patients with ARR were extracted (n=25). Simultaneously, ARR patients were matched to PAD patients in terms of age, gender, prevalence of diabetes, hypertension, dyslipidemia, obesity, and the smoking rate (n=25 in both groups). Real-time polymerase chain reaction was performed to measure the bacterial counts, while the enzyme-linked immunosorbent assay method was used to measure anti-bacterial antibody titers and proinflammatory cytokine levels in serum. RESULTS: PAD patients had more missing teeth (18.4±2.0) and higher serum levels of C-reactive protein (1.57±0.85 mg/dL) and tumor necrosis factor-alpha (70.3±5.7 pg/mL) than ARR patients (12.0±1.7, 0.38±0.21 mg/dL, and 39.3±4.5 pg/mL, respectively). Meanwhile, no statistically significant differences were found in other dental clinical measurements, bacterial antibody titers, or bacterial counts between the 2 groups. CONCLUSIONS: Our findings suggested that PAD patients had poorer oral and periodontal state with enhanced systemic inflammation.