Oral angiotensin-converting enzyme inhibitor captopril protects the heart from Porphyromonas gingivalis LPS-induced cardiac dysfunction in mice.

Although angiotensin converting enzyme (ACE) inhibitors are considered useful for the treatment of human heart failure, some experimental failing-heart models have shown little beneficial effect of ACE inhibitors in animals with poor oral health, particularly periodontitis. In this study, we examined the effects of the ACE inhibitor captopril (Cap; 0.1 mg/mL in drinking water) on cardiac dysfunction in mice treated with Porphyromonas gingivalis lipopolysaccharide (PG-LPS) at a dose (0.8 mg/kg/day) equivalent to the circulating level in patients with periodontal disease. Mice were divided into four groups: 1) Control, 2) PG-LPS, 3) Cap, and 4) PG-LPS + Cap. After1 week, we evaluated cardiac function by echocardiography. The left ventricular ejection fraction was significantly decreased in PG-LPS-treated mice compared to the control (from 66 ± 1.8 to 59 ± 2.5%), while Cap ameliorated the dysfunction (63 ± 1.1%). The area of cardiac fibrosis was significantly increased (approximately 2.9-fold) and the number of apoptotic myocytes was significantly increased (approximately 5.6-fold) in the heart of PG-LPS-treated group versus the control, and these changes were suppressed by Cap. The impairment of cardiac function in PG-LPS-treated mice was associated with protein kinase C δ phosphorylation (Tyr-311), leading to upregulation of NADPH oxidase 4 and xanthine oxidase, and calmodulin kinase II phosphorylation (Thr-286) with increased phospholamban phosphorylation (Thr-17). These changes were also suppressed by Cap. Our results suggest that the renin-angiotensin system might play an important role in the development of cardiac diseases induced by PG-LPS.

Effects of the angiotensin-converting enzyme inhibitor captopril on occlusal-disharmony-induced cardiac dysfunction in mice.

Occlusal disharmony is known to affect not only the oral cavity environment, but also the autonomic nervous system in the heart. Since the renin-angiotensin system (RAS) inhibitor captopril (Cap) is one of the first-line drugs for preventing cardiac remodeling in patients with heart failure, we hypothesized that Cap might prevent cardiac dysfunction induced by occlusal disharmony. Here, to test this idea, we used our bite-opening (BO) mouse model, which was developed by cementing a suitable appliance onto the mandibular incisor. Mice were divided into four groups: (1) Control, (2) BO, (3) Cap, and (4) BO + Cap. After 2 weeks, we evaluated cardiac function by echocardiography and confirmed that cardiac function was significantly decreased in the BO group compared to the control, while Cap ameliorated the dysfunction. Cardiac fibrosis, myocyte apoptosis and oxidative stress-induced myocardial damage in the BO group were significantly increased versus the control, and these increases were suppressed by Cap. Cardiac dysfunction induced by BO was associated with dual phosphorylation on PKCδ (Tyr-311/Thr-505), leading to activation of CaMKII with increased phosphorylation of RyR2 and phospholamban. Our results suggest that the RAS might play an important role in the development of cardiac diseases induced by occlusal anomalies.

Vidarabine, an anti-herpes agent, improves Porphyromonas gingivalis lipopolysaccharide-induced cardiac dysfunction in mice.

In this work, we examined the involvement of type 5 adenylyl cyclase (AC5) in cardiac dysfunction induced in mice given Porphyromonas gingivalis lipopolysaccharide (PG-LPS) at a dose equivalent to the circulating levels in periodontitis (PD) patients. Cardiac function was significantly decreased in mice given PG-LPS compared to the control, but treatment for 1 week with the AC5 inhibitor vidarabine ameliorated the dysfunction. Cardiac fibrosis and myocyte apoptosis were significantly increased in the PG-LPS group, but vidarabine blocked these changes. The PG-LPS-induced cardiac dysfunction was associated with activation of cyclic AMP/Ca2+-calmodulin-dependent protein kinase II signaling and increased phospholamban phosphorylation at threonine 17. These results suggest that pharmacological AC5 inhibition may be a promising approach to treat PD-associated cardiovascular disease.

CAR-Modified Vγ9Vδ2 T Cells Propagated Using a Novel Bisphosphonate Prodrug for Allogeneic Adoptive Immunotherapy.

The benefits of CAR-T therapy could be expanded to the treatment of solid tumors through the use of derived autologous αß T cell, but clinical trials of CAR-T therapy for patients with solid tumors have so far been disappointing. CAR-T therapy also faces hurdles due to the time and cost intensive preparation of CAR-T cell products derived from patients as such CAR-T cells are often poor in quality and low in quantity. These inadequacies may be mitigated through the use of third-party donor derived CAR-T cell products which have a potent anti-tumor function but a constrained GVHD property. Vγ9Vδ2 TCR have been shown to exhibit potent antitumor activity but not alloreactivity. Therefore, in this study, CAR-T cells were prepared from Vγ9Vδ2 T (CAR-γδ T) cells which were expanded by using a novel prodrug PTA. CAR-γδ T cells suppressed tumor growth in an antigen specific manner but only during a limited time window. Provision of GITR co-stimulation enhanced anti-tumor function of CAR-γδ T cells. Our present results indicate that, while further optimization of CAR-γδ T cells is necessary, the present results demonstrate that Vγ9Vδ2 T cells are potential source of 'off-the-shelf' CAR-T cell products for successful allogeneic adoptive immunotherapy.

Oxidation-induced nanolite crystallization triggered the 2021 eruption of Fukutoku-Oka-no-Ba, Japan.

Nanometer-sized crystals (nanolites) play an important role in controlling eruptions by affecting the viscosity of magmas and inducing bubble nucleation. We present detailed microscopic and nanoscopic petrographic analyses of nanolite-bearing and nanolite-free pumice from the 2021 eruption of Fukutoku-Oka-no-Ba, Japan. The nanolite mineral assemblage includes biotite, which is absent from the phenocryst mineral assemblage, and magnetite and clinopyroxene, which are observed as phenocrysts. The boundary between the nanolite-bearing brown glass and nanolite-free colorless glass is either sharp or gradational, and the sharp boundaries also appear sharp under the transmitted electron microscope. X-ray absorption fine structure (XAFS) analysis of the volcanic glass revealed that the nanolite-free colorless glass records an oxygen fugacity of QFM + 0.98 (log units), whereas the nanolite-bearing brown glass records a higher apparent oxygen fugacity (~ QFM + 2). Thermodynamic modelling using MELTS indicates that higher oxygen fugacities increase the liquidus temperature and thus induced the crystallization of magnetite nanolites. The hydrous nanolite mineral assemblage and glass oxygen fugacity estimates suggest that an oxidizing fluid supplied by a hot mafic magma induced nanolite crystallization in the magma reservoir, before the magma fragmentation. The oxidation-induced nanolite crystallization then enhanced heterogeneous bubble nucleation, resulting in convection in the magma reservoir and triggering the eruption.

Clinical features of olfactory dysfunction in elderly patients.

OBJECTIVE: This study aimed to investigate the causes of olfactory dysfunction (OD) and to discuss the benefits of understanding the characteristics of OD in elderly patients. METHODS: A total of 4300 patients with OD who were treated at our hospital between January 1996 and December 2020 were retrospectively analyzed. There were 1833 men and 2467 women, with ages ranging from 4 to 95 years. The patients were divided into two groups: younger (less than 65 years old, n = 2947) and elderly (65 years old or more, n = 1353) groups. Causative diseases were chronic rhinosinusitis (CRS), post-viral (PV), post-traumatic (PT), central nervous system dysfunction (CNS), peripheral nervous system dysfunction (PNS), congenital, psychogenic, and unknown. Visual analogue scale (VAS) and olfactory detection and recognition thresholds using the T&T olfaction test were used to evaluate olfaction. The mean detection and recognition thresholds, as well as the deviation difference (the difference between the mean detection and recognition thresholds) were compared by causative disease. RESULTS: The causative diseases in elderly group were CRS (32%), PV (28%), PT (3%), CNS (2%), and PNS (4%). OD of unknown cause was significantly more in elderly (30%) than in younger patients (12%). Olfactory detection and recognition thresholds in elderly group were significantly worse than in younger group (p < 0.05). The olfactory detection and recognition thresholds were not any significant differences between patients with OD of unknown cause and those with CNS. CONCLUSION: OD of unknown cause was predominantly observed in elderly group. The olfactory acuity of OD of unknown cause was similar to CNS OD. These findings suggest the importance of continuous follow-up due to the potential of neurodegenerative diseases in elderly OD patients.

Chimeric antigen receptor T-cell therapy targeting a MAGE A4 peptide and HLA-A*02:01 complex for unresectable advanced or recurrent solid cancer: protocol for a multi-institutional phase 1 clinical trial.

INTRODUCTION: Adoptive cell transfer of genetically engineered T cells is a promising treatment for malignancies; however, there are few ideal cancer antigens expressed on the cell surface, and the development of chimeric antigen receptor T cells (CAR-T cells) for solid tumour treatment has been slow. CAR-T cells, which recognise major histocompatibility complex and peptide complexes presented on the cell surface, can be used to target not only cell surface antigens but also intracellular antigens. We have developed a CAR-T-cell product that recognises the complex of HLA-A*02:01 and an epitope of the MAGE-A4 antigen equipped with a novel signalling domain of human GITR (investigational product code: MU-MA402C) based on preclinical studies. METHODS AND ANALYSIS: This is a dose-escalation, multi-institutional, phase 1 study to evaluate the tolerability and safety of MU-MA402C for patients with MAGE A4-positive and HLA-A*02:01-positive unresectable advanced or recurrent solid cancer. Two dose cohorts are planned: cohort 1, MU-MA402C 2×108/person; cohort 2, MU-MA402C 2×109/person. Prior to CAR-T-cell infusion, cyclophosphamide (CPA) and fludarabine (FLU) will be administered as preconditioning chemotherapy. Three evaluable subjects per cohort, for a total of 6 subjects (maximum of 12 subjects), will be recruited for this clinical trial. The primary endpoints are safety and tolerability. The severity of each adverse event will be evaluated in accordance with Common Terminology Criteria for Adverse Events V.5.0. The secondary endpoint is efficacy. Antitumour response will be evaluated according to Response Evaluation Criteria in Solid Tumours V.1.1. ETHICS AND DISSEMINATION: This clinical trial will be conducted in accordance with the current version of Good Clinical Practice. The protocol was approved by the Clinical Research Ethics Review Committee of Mie University Hospital (approval number F-2021-017). The trial results will be published in peer-reviewed journals and/or disseminated through international conferences. TRIAL REGISTRATION NUMBER: jRCT2043210077.

Efficacy and feasibility of cryoballoon ablation for atrial fibrillation in patients with heart failure: A large-scale multicenter study.

INTRODUCTION: Data are limited regarding outcomes of cryoballoon ablation for atrial fibrillation (AF) in patients with heart failure (HF). This large-scale multicenter study aimed to evaluate the prognosis of patients with HF after cryoballoon ablation for AF. METHODS: Among 3655 patients undergoing cryoballoon ablation at 17 institutions, 549 patients (15%) (391 with paroxysmal AF and 158 with persistent AF) diagnosed with HF preoperatively were analyzed. Clinical endpoints were recurrence, mortality, and HF hospitalization after ablation. RESULTS: Most patients had a preserved left ventricular ejection fraction (LVEF) ≥ 50%. During a mean follow-up period of 25.7 months, recurrence, all-cause death, and HF hospitalization occurred in 29%, 4.0%, and 4.8%, respectively. Cardiac function on echocardiography and B-type natriuretic peptide (BNP) levels significantly improved postoperatively, and the effect was more pronounced in the nonrecurrence group. Major complications occurred in 33 patients (6.0%), but most complications were phrenic nerve palsy (3.6%). Although death and HF hospitalization occurred more frequently in patients with LVEF ≤ 40% (n = 73) and New York Heart Association (NYHA) class III-IV (n = 19) than other subgroups, the BNP levels, and LVEF significantly improved after ablation in all LVEF and NYHA class subgroups. High BNP levels, NHYA class, CHADS2 score, and structural heart disease, but not postablation recurrence, independently predicted death, and HF hospitalization on multivariate analysis. The patients with tachycardia-induced cardiomyopathy had better recovery of BNP levels and LVEF after ablation than those with structural heart disease. CONCLUSIONS: Cryoballoon ablation for AF in HF patients is feasible and leads to significantly improved cardiac function.

Role of TLR4 signaling on Porphyromonas gingivalis LPS-induced cardiac dysfunction in mice.

Oral infections, particularly periodontitis, are a well-established risk factor for cardiovascular diseases, although the molecular mechanisms involved remain elusive. The aims of the present study were to investigate the effects of lipopolysaccharide derived from Porphyromonas gingivalis (PG-LPS) on cardiac function in mice, and to elucidate the underlying mechanisms. Mice (C57BL/6) were injected with PG-LPS (0.8 mg/kg/day) with or without an inhibitor of Toll-like receptor 4 (TLR4) signaling (TAK-242, 0.8 mg/kg/day) for 4 weeks. Left ventricular ejection function was significantly decreased at 1 week (from 67 ± 0.5 to 58 ± 1.2%) and remained low at 4 weeks (57 ± 1.0%). The number of apoptotic myocytes was increased (approximately 7.4-fold), the area of fibrosis was increased (approximately 3.3-fold) and the number of 8-hydroxydeoxyguanosine-positive myocytes, a sensitive indicator of oxidative DNA damage, was increased (approximately 7.6-fold) at 4 weeks in the heart of PG-LPS treated mice. However, levels of various serum pro-inflammatory cytokines in PG-LPS-treated mice were similar to those in control mice. The impairment of cardiac function in PG-LPS-treated mice appears to involve activation of TLR4-NADPH oxidase (NOX) 4 signaling, leading to abundant production of reactive oxygen species and Ca2+ leakage from sarcoplastic reticulumn induced by calmodulin kinase II (CaMKII)-mediated phosphorylation of phospholamban (at Thr-17) and ryanodine receptor 2 (at Ser-2448). Pharmacological inhibition of TLR4 with TAK-242 attenuated the changes in cardiac function in PG-LPS-treated mice. Our results indicate that TLR4-NOX4 signaling may be a new therapeutic target for treatment of cardiovascular diseases in patients with periodontitis.

Pathologic complete response with pembrolizumab plus axitinib in metastatic renal cell carcinoma.

Immunotherapy-based combinations have played a central role in the treatment of metastatic renal cell carcinoma, and long-term survival of patients is expected. In this context, it is clear that a certain number of patients can achieve a complete response. However, the diagnosis of complete response is usually based on imaging, and there are few cases of pathological complete response. In this study, we report a case of a patient with metastatic renal cell carcinoma who was treated with pembrolizumab plus axitinib, followed by resection of the primary tumor and metastatic lesions, and pathologically achieved a complete response.

Vidarabine, an anti-herpes agent, prevents occlusal-disharmony-induced cardiac dysfunction in mice.

We recently reported a positive relationship between occlusal disharmony and cardiovascular disease via activation of ß-adrenergic signaling in mice. Furthermore, inhibition of type 5 adenylyl cyclase (AC5), a major cardiac subtype in adults, protects the heart against oxidative stress. Here, we examined the role of AC5 in the development of occlusal-disharmony-induced cardiovascular disease in bite-opening (BO) mice, prepared by cementing a suitable appliance onto the mandibular incisor. We first examined the effects of BO treatment on cardiac function in mice treated or not treated for 2 weeks with vidarabine, which we previously identified as an inhibitor of cardiac AC. Cardiac function was significantly decreased in the BO group compared to the control group, but vidarabine ameliorated the dysfunction. Cardiac fibrosis, myocyte apoptosis and myocyte oxidative DNA damage were significantly increased in the BO group, but vidarabine blocked these changes. The BO-induced cardiac dysfunction was associated with increased phospholamban phosphorylation at threonine-17 and serine-16, as well as increased activation of the Ca2+-calmodulin-dependent protein kinase II/receptor-interacting protein 3 signaling pathway. These data suggest that AC5 inhibition with vidarabine might be a new therapeutic approach for the treatment of cardiovascular disease associated with occlusal disharmony.

Effects of chronic Porphylomonas gingivalis lipopolysaccharide infusion on cardiac dysfunction in mice.

OBJECTIVE: Periodontitis (PD) is a chronic inflammatory disease of tooth-supportive tissue. An association between PD and cardiovascular disease (CVD) has been established. Although PD is generally accepted as a risk factor for CVD, the existence of a relationship remains debatable. Possible mechanisms include the release of inflammatory mediators such as lipopolysaccharide (LPS), which may spread systemically and promote CVD. METHODS: To compare the effects of lipopolysaccharide derived from Porphylomonas gingivalis (PG-LPS) on cardiac muscle in mice, mice were treated for 1 week with/without PG-LPS at a dose equivalent to the circulating level in PD patients (0.8 mg/kg/day). RESULTS: Cardiac function in terms of left ventricular ejection function was significantly decreased at 1 week compared to that in the control (from 66 ± 0.5% to 57 ± 1.1%). Compared to the controls, the number of apoptotic myocytes and the area of fibrosis were significantly increased by approximately 2.7-fold and 14-fold, respectively. The impairment of cardiac function appeared to involve the activation of cAMP/PKA signaling and cAMP/calmodulin kinase II signaling (CaMKII), leading to cardiac fibrosis, myocyte apoptosis and heart failure. CONCLUSIONS: Our results indicate that cAMP/PKA and cAMP/CaMKII signaling may be a new therapeutic target for the treatment of cardiovascular diseases in patients with periodontitis.

Impact of heart failure severity on bone mineral density among older patients with heart failure.

The study aimed to identify factors related to bone mineral density (BMD) among older patients with heart failure (HF). A total of 70 consecutive patients with HF aged 65 years or older who were admitted to an acute hospital due to worsening condition were enrolled before discharge. BMD of the femoral neck was evaluated using the DEXA method. Physical function, as well as echocardiographic and laboratory findings including biomarker of HF severity were collected. Bivariate and multiple regression analyses were employed to determine the association between BMD and the clinical variables. Bivariate analysis determined that age, grip strength, walking speed, serum albumin, and N-terminal pro B-type natriuretic peptide (NT-proBNP) were significantly correlated with BMD (P < 0.01), whereas other clinical parameters were not. The multiple regression analysis identified NT-proBNP as an independent related factor for BMD after adjusting with confounding clinical variables. NT-proBNP was independently related to BMD among older patients with HF. Our results suggest the inclusion of bone fracture prevention strategies in disease management programs, especially for older patients with HF.

Circulating miR-489 as a potential new biomarker for idiopathic dilated cardiomyopathy.

OBJECTIVES: MicroRNAs (miRNA) are functional RNAs that have emerged as pivotal gene expression regulators in cardiac disease. Although several cardiomyocyte miRNAs have been reported to play roles in heart failure progression among patients with idiopathic dilated cardiomyopathy (DCM), the role of circulating miRNAs has not yet been well-examined. METHODS: After total RNA extraction from the peripheral blood samples of three control participants and six patients with DCM, miRNA profiling was performed using miRNA arrays. Based on the results of this initial screening, real-time polymerase chain reaction (RT-PCR) was used to perform a quantitative analysis of blood samples from a larger number of matched patients (DCM, n=20; controls, n=5). Finally, the correlations between specific miRNA expression levels and hemodynamic parameters were analyzed. RESULTS: A primary screening of 2,565 miRNAs resulted in the identification of nine miRNA candidates. Quantitative RT-PCR results revealed significantly increased miR-489 expression levels in the DCM group. Moreover, there was a significant positive correlation between miR-489 expression level and left ventricular ejection fraction. CONCLUSIONS: Our results suggest that circulating miR-489 could be a potential noninvasive diagnostic biomarker for DCM. Additionally, the quantification of circulating miR-489 may have value as a potential prognostic marker for patients with DCM.

Impact of physical function on indeterminable anaerobic threshold in patients with heart failure.

BACKGROUND: Anaerobic threshold (AT) during cardiopulmonary exercise testing (CPET) is not always determinable in patients with heart failure (HF). However, little is known about the clinical features of patients with HF who have indeterminable AT. Therefore, the present study aimed to clarify the clinical features of such patients. METHODS: A total of 70 patients with HF (58 males; age: 68±12 years) who underwent CPET during hospitalization were divided into two groups: determinable AT (n=50) and indeterminable AT (n=20). Physical function, echocardiographic results, and laboratory findings were subsequently determined. RESULTS: Univariate analyses showed that the indeterminable AT group had significantly higher age and left ventricular ejection fraction, and significantly lower body mass index, calf circumference, handgrip strength, walking speed, serum hemoglobin, and serum albumin than the determinable AT group. Multiple logistic regression analysis identified handgrip strength and walking speed as independent predictive factors for indeterminable AT. Receiver-operating characteristic analyses revealed that handgrip strength of 21.2 kg and walking speed of 0.97 m/s were optimal cutoff values for differentiating patients who were likely to experience indeterminable AT. CONCLUSIONS: The present study identified handgrip strength and walking speed as powerful predictors for indeterminable AT with HF.

Effect of cardiac rehabilitation on circulating microRNA expression in heart failure: a preliminary study.

OBJECTIVES: There are benefits of exercise-based cardiac rehabilitation (CR) in patients with heart failure (HF), but their underlying molecular mechanisms remain elusive. The effect of CR on the expression profile of circulating microRNAs (miRNAs), which are short noncoding RNAs that regulate posttranscriptional expression of target genes, is unknown. If miRNAs respond to changes following CR for HF, then serum profiling of miRNAs may reveal cardioprotective mechanisms of CR. METHODS: This study enrolled three hospitalized patients with progressed systolic HF and three normal volunteer controls. In patients, CR was initiated after improvement of HF, which included 2 weeks of bicycle ergometer and resistance exercises. Genome-wide expression profiling of circulating miRNAs was performed using microarrays for the patients (mean±SD age, 60.0±12.2 years) and controls (58.7±0.58 years). Circulating miRNA expression profiles were compared between patients with HF before and after CR and the controls. RESULTS: Expression levels of two miRNAs were significantly different in patients before CR compared with controls and patients after CR. The expression of hsa-miR-125b-1-3p was significantly downregulated and that of hsa-miR-1290 was significantly upregulated in patients before CR. CONCLUSIONS: When performing CR, expression of certain circulating miRNAs in patients with HF is restored to nonpathological levels. The benefits of CR for HF may result from regulation of miRNAs through multiple effects of gene expression.

An experimental system for time-resolved x-ray diffraction of deforming silicate melt at high temperature.

Rheological behavior of silicate melts controls the dynamics of volcanic eruptions. Previous experimental studies have investigated melt viscosity and found non-Newtonian behavior of the melt under a high shear rate. However, the relationship between macroscopic rheology and atomic-scale behavior under shear remains unclear. We developed an experimental system for time-resolved x-ray diffraction (XRD) at high temperature to investigate the atomic-scale structural change in melts under shear. The manufactured deformation apparatus and heating furnace were set on the synchrotron radiation x-ray beamline (BL20XU) of SPring-8; the XRD pattern of the melt at high temperature could be observed using this system because the furnace mainly consists of a boron nitride cylinder with high x-ray transmittance. Here, we report results of fiber elongation experiments for a soda-lime melt. Melt fibers with ∼0.7 mm in diameter and ∼27 mm long were elongated at 100 µm sec-1 at temperatures of 595 °C and 620 °C, and the XRD pattern was obtained every 100 msec. Brittle failure of the melt occurred at 595 °C, whereas the melt viscously elongated at 620 °C. The XRD patterns obtained during elongation did not indicate any clear change immediately before brittle failure. The intensity of the XRD pattern decreased with the elongation at 620 °C, although there was no clear variation in its shape. These results indicate that the atomic-scale structure observed by XRD may not change during the elastic and viscous elongation of the soda-lime melt. This experimental system will be further developed and applied to more polymerized and natural silicate melts.

Gender differences in eating behavior and masticatory performance: An analysis of the Three-Factor-Eating Questionnaire and its association with body mass index in healthy subjects.

OBJECTIVES: The Three-Factor-Eating Questionnaire (TFEQ) is an established instrument to assess eating behavior in terms of dietary restraint, disinhibition and hunger. METHODS: The aims of this study were to examine (1) the correlation between eating behavior and body mass index (BMI), (2) the correlation between eating behavior and masticatory performance in terms of bite size and eating speed, and (3) the effects of gender on these correlations in 56 healthy subjects (33 males [21.9 ± 2.8 years old] and 23 females [21.7 ± 2.2 years old]). RESULTS: We found a significant correlation between restraint and BMI only in females and between hunger and BMI only in males. However, disinhibition and BMI were significantly correlated in both males and females. We also found a significant correlation between bite size and hunger only in males and between eating speed and disinhibition in both males and females. CONCLUSIONS: These findings underline the importance of gender-specific counselling and behavioral treatment of obesity.

Effects of occlusal disharmony on susceptibility to atrial fibrillation in mice.

Tooth loss or incorrect positioning causes occlusal disharmony. Furthermore, tooth loss and atrial fibrillation (AF) are both risk factors for ischemic stroke and coronary heart disease. Therefore, we hypothesized that occlusal disharmony-induced stress increases susceptibility to AF, and we designed the present study to test this idea in mice. Bite-opening (BO) was done by cementing a suitable appliance onto the mandibular incisor to cause occlusal disharmony by increasing the vertical height of occlusion by 0.7 mm for a period of 2 weeks. AF susceptibility, evaluated in terms of the duration of AF induced by transesophageal burst pacing, was significantly increased concomitantly with atrial remodeling, including fibrosis, myocyte apoptosis and oxidative DNA damage, in BO mice. The BO-induced atrial remodeling was associated with increased calmodulin kinase II-mediated ryanodine receptor 2 phosphorylation on serine 2814, as well as inhibition of Akt phosphorylation. However, co-treatment with propranolol, a non-selective ß-blocker, ameliorated these changes in BO mice. These data suggest that improvement of occlusal disharmony by means of orthodontic treatment might be helpful in the treatment or prevention of AF.

Effects of occlusal disharmony on cardiac fibrosis, myocyte apoptosis and myocyte oxidative DNA damage in mice.

Occlusal disharmony leads to morphological changes in the hippocampus and osteopenia of the lumbar vertebra and long bones in mice, and causes stress. Various types of stress are associated with increased incidence of cardiovascular disease, but the relationship between occlusal disharmony and cardiovascular disease remain poorly understood. Therefore, in this work, we examined the effects of occlusal disharmony on cardiac homeostasis in bite-opening (BO) mice, in which a 0.7 mm space was introduced by cementing a suitable applicance onto the mandibular incisior. We first examined the effects of BO on the level of serum corticosterone, a key biomarker for stress, and on heart rate variability at 14 days after BO treatment, compared with baseline. BO treatment increased serum corticosterone levels by approximately 3.6-fold and the low frequency/high frequency ratio, an index of sympathetic nervous activity, was significantly increased by approximately 4-fold by the BO treatment. We then examined the effects of BO treatment on cardiac homeostasis in mice treated or not treated with the non-selective ß-blocker propranolol for 2 weeks. Cardiac function was significantly decreased in the BO group compared to the control group, but propranolol ameliorated the dysfunction. Cardiac fibrosis, myocyte apoptosis and myocyte oxidative DNA damage were significantly increased in the BO group, but propranolol blocked these changes. The BO-induced cardiac dysfunction was associated with increased phospholamban phosphorylation at threonine-17 and serine-16, as well as inhibition of Akt/mTOR signaling and autophagic flux. These data suggest that occlusal disharmony might affect cardiac homeostasis via alteration of the autonomic nervous system.