Abstract
Introduction
Periodontal disease (PD) is a highly prevalent chronic infectious disease that affects the protective and supporting structures of the teeth. In addition to the negative impact on oral health, periodontitis also has systemic effects. For example, epidemiological evidence indicates an association between periodontitis and coronary artery disease (CAD).
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Humphrey
PD can be prevented or attenuated by the innate immune response, involving a broad spectrum of cells and soluble proteins that recognize and exert effector functions in response to pathogens. 17 Mannose-binding lectin (MBL) is an innate immune protein that binds to mannose-containing carbohydrates present on the surface of bacteria, triggering activation of the complement cascade, and therefore facilitating clearance of bacteria. Thus, MBL promotes defense against invasive pathogens. Experimental studies in rats showed that the MBL pathway is involved in ischemia-induced inflammation, and administration of anti-MBL antibodies attenuated this inflammatory response of ischemia/reperfusion.18,19 A human study also showed that patients with type I diabetes with macro- or microvascular disease had significantly higher levels of MBL compared with patients with uncomplicated type I diabetes. 20 MBL serum concentration may also be a possible indicator of atherosclerotic plaque instability. A recent study showed that MBL is present in the atheroma necrotic nucleus and in the middle layer of the vascular wall, contributing to the instability of atheromatous plaques. 21
SIRT1 regulates a variety of cellular functions, such as genome and metabolic pathway integrity, and is directly associated with greater longevity.
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SIRT1 acts in the regulation of inflammatory responses.23,24 A study in rats showed that resveratrol and curcumin promoted a decrease in experimentally induced periodontal lesions by reducing oxidative stress, possibly mediated by sirtuin pathway activation.
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The beneficial effects of SIRT1 on inflammation, lipid metabolism, and atherosclerosis have been well documented in preclinical and animal studies.26,27 Stein
Previous studies have shown that SIRT1 plays an important role in protecting against age-related vascular diseases, including inhibiting neointimal formation
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and protecting against the atherosclerosis process.
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An
Periodontal treatment focuses on the elimination of pathological oral microorganisms, avoiding exacerbation of inflammatory processes. Animal studies have shown that periodontitis reduced SIRT1 levels. On the other hand, increased levels of SIRT1 prevented the progression of periodontal disease. 36 However, no studies have examined the impact of the association of periodontal and atherosclerotic diseases on serum MBL and SIRT1 levels before and after PD treatment. We hypothesized that periodontal treatment in patients with both CAD and PD with subsequent decrease in inflammatory process and MBL serum concentration will also result in increased SIRT1 levels and, therefore, the possible beneficial effects of higher SIRT1 levels on these diseases. Thus, this study analyzed the impact of PD treatment on serum concentrations and on the interrelationship of SIRT1 and MBL in individuals with and without stable chronic CAD.
Methods
This prospective study analyzed 78 individuals aged 45–79 years, 38 women and 40 men, between October 2016 and September 2018. Patients were divided into four groups according to the absence or presence of PD (PD− or PD+) and of CAD (CAD− or CAD+): (1) control CAD−/PD− group: 20 healthy participants; (2) CAD+/PD− group: 18 patients with CAD without PD; (3) CAD−/PD+ group: 20 patients with PD without CAD; and (4) CAD+/PD+ group: 20 patients with CAD and PD.
The diagnosis of PD was confirmed by clinical evaluation and periodontal examination. The inclusion criteria for the CAD group were patients who had at least six teeth with periodontal probing depth (PPD) and clinical attachment loss (CAL) ⩾5 mm, with 30% of sites with PPD and CAL ⩾4 mm and bleeding on probing (BOP). Individuals who had a periodontal with no insertion loss, PPD ⩽3 mm, BOP in less than 10% of the sites, and no radiographic bone loss were classified as periodontally healthy.
The treatment was performed to eliminate the inflammatory process and to achieve a smooth dental surface without biofilm and stone. Patients in the periodontitis group underwent supra- and subgingival mechanical scaling and root planing using ultrasonic scalers and manual instruments, after administration of local anesthesia. PD patients were also treated with metronidazole (1.2 g/d for 14 days) and amoxicillin (1.5 g/d for 14 days). Previous studies showed better results with adjunctive use of systemic antibiotic therapy to the treatment of PD.37,38 The principal investigator and examiner (PMVC) underwent a calibration to establish consistency and to obtain reliable results in periodontal examinations. Individuals without PD did not receive any treatment.
The inclusion criteria for the CAD group were patients who had a history of CAD, characterized by the presence of a coronary lesion ⩾70% on past coronary angiography, and also patients that previously underwent to percutaneous or surgical coronary revascularization. Patients were asymptomatic or with stable grade I/II of the Canadian Cardiovascular Society scale. 39 Healthy participants were volunteers with a normal clinical history, physical examination, and resting electrocardiogram.
Exclusion criteria were uncontrolled diabetes, chronic kidney disease, smoking, HIV, hepatitis B and C, pregnancy, brachytherapy, orthodontic treatment, anti-inflammatory drugs and corticosteroids, periodontal treatment less than 6 months previously and allergic to the antibiotics prescribed in this protocol. The study was approved by the Ethics Committee (CAPPesq) of the Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, BR (CAAE: 55556116.0.0000.0068). All participants signed a consent form. The study is registered at ClinicalTrials.org (identifier: NCT03753451).
Laboratory tests
A 10-ml sample of peripheral vein blood was collected at baseline and at the end of the study after a 12-h fast. Patients had blood sample reassessed 1 month after periodontal treatment. The biochemical tests analyzed were triglycerides, total cholesterol, high-density lipoprotein (HDL) cholesterol, glucose, CRP, MBL, and SIRT1. Glucose, triglycerides, and HDL cholesterol were obtained using the enzymatic calorimetry method. Low-density lipoprotein (LDL) cholesterol was calculated by Friedwald’s equation. Measurements were performed at Dimension RxL (Siemens Healthcare Diagnostic Inc., Newark, DE, USA). The determination of ultrasensitive CRP was performed by immunonephelometry with dedicated reagents on Siemens Healthcare BN-II equipment (Marburg, Hessen, Germany). Serum MBL levels were determined by enzyme-linked immunosorbent assay (ELISA) using anti-MBL monoclonal antibody HYB 131-01 (BioPorto Diagnostics A/S, Copenhagen, Denmark). SIRT1 concentrations were determined using an ELISA kit (Usin Life Science, Wuhan, Hubei, China). Before and after the interventions, SIRT1 samples were analyzed in duplicate on the same ELISA plate using a Multiscan FC plate reader (Thermo Fisher Scientific Oy, Vantaa, Finland), with a 12% coefficient of variation according to the manufacturer’s instructions.
Statistical analysis
The sample size calculation was made by the difference between the serum SIRT1 levels, before and after periodontal treatment. The expected values were based on a previous study conducted in our service in healthy individuals.
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The difference between the means for the control group was 1 mg with standard deviation of 1 mg and for intervention groups was 2 mg with standard deviation of 1 mg. The test power was β = 0.90 and α = 0.05. The estimated number of the sample was 20 individuals for each group. Chi-square test was used for analysis of categorical variables. Correlations between variables were performed using Spearman’s correlation test. The paired Student’s
Results
Clinical features and laboratory data of participants before and at the end of study are shown in Table 1. After PD treatment of the CAD+/PD+ and CAD−/ PD+ groups, we observed a reduction in the plaque index from 63.9% ± 5.7% to 37.8% ± 10.5% (
Clinical and periodontal features and laboratory data of participants before and at the end of study.
BMI, body mass index; HDL, high-density lipoprotein; LDL, low-density lipoprotein; MBL, mannose-binding lectin; SIRT1, sirtuin-1; usCRP, ultrasensitive C-reactive protein. *
Discussion
Our study shows that PD treatment is associated with reduced serum MBL and CRP concentrations and increased SIRT1 serum levels. Patients in the CAD+/DP+ group had the highest initial MBL concentration, suggesting an additive inflammatory power of the association of CAD and PD in the serum MBL concentration. Our study also showed higher initial mean MBL values in the CAD patient groups compared with the control participants. The relationship between MBL and atherosclerotic disease is controversial and poorly understood. Increased serum concentration of MBL was associated with a higher risk of myocardial infarction, as well as a worse prognosis in the surgical revascularization of CAD.
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On the other hand, MBL deficiency at serum levels <100 ng/ml was also associated with a higher incidence of myocardial infarction and higher CAD progression.42,43 For PD, Maffei
Our study also shows that PD treatment is associated with increased SIRT1 serum concentration. The increase in SIRT1 serum concentration was probably a consequence of PD treatment. SIRT1 is a potent regulator of human periodontal ligament cell differentiation and may have clinical implications for periodontal bone regeneration. 47 Therefore, in our study, there is still the possibility that increased SIRT1 levels could partially influenced a better clinical response to PD treatment. However, studies analyzing the metabolic pathway of SIRT1 in patients with PD are scarce. Higher SIRT1 serum concentration reduced oxidative stress; this increase may be beneficial in patients with PD. The reduction in CAL achieved through periodontal treatment was associated with a reduction in plasma levels of reactive oxygen metabolites. 48 The treatment of PD was associated with lower levels of proinflammatory biomarkers. Studies in periodontal ligament cell cultures have also shown a reduction in proinflammatory substances, such as matrix metalloproteinases and interleukins, a process dependent, at least in part, on SIRT1 signaling.49,50 Nonetheless, no studies have analyzed the relationship between serum levels of SIRT1 and MBL, alone or combined, in patients with PD and CAD.
In our study we also observed a significant reduction in serum concentration of total cholesterol and LDL cholesterol and reduced levels of HDL cholesterol after PD treatment in the CAD+/DP+ group. This result was similar to results observed in previous studies. 51 Possible explanations for these findings are the influence of multiple proinflammatory cytokines in increasing the synthesis of triglyceride rich lipoproteins and in interfering in metabolic enzymatic pathways of lipoproteins, such as the lipoprotein lipase. This prospective, case-controlled study with a well-selected population, has some limitations, which include the relative small number of participants, despite the statistically appropriate sample size, and the short follow-up period.
In conclusion, our study shows a reduction in serum MBL and CRP concentration and an increase in serum SIRT1 levels after PD treatment, providing a better biochemical and metabolic blood profile. It is possible that this improvement in blood rheology with a reduction of the systemic immunoinflammatory process had a positive impact on vascular health, and in the long term could contribute to lower atherosclerosis progression. Similarly, increased serum concentration of SIRT1 could also have a clinical benefit by reducing the severity of PD and even preserving periodontal health. However, prospective and long-term follow-up studies using drugs that increase serum concentration of SIRT1 are mandatory to assess the impact of higher levels of SIRT1 on prognosis in PD and CAD.
