Aging as a Risk Factor on the Immunoexpression of Pro-Inflammatory IL-1β, IL-6 and TNF-α Cytokines in Chronic Apical Periodontitis Lesions

Cytokines in gingivitis and periodontitis: from pathogenesis to therapeutic targets

Chronic inflammatory processes in the oral mucosa and periodontitis are common disorders caused by microflora and microbial biofilms. These factors activate both the innate and adaptive immune systems, leading to the production of pro-inflammatory cytokines. Cytokines are known to play a crucial role in the pathogenesis of gingivitis and periodontitis and have been proposed as biomarkers for diagnosis and follow-up of these diseases. They can activate immune and stromal cells, leading to local inflammation and tissue damage. This damage can include destruction of the periodontal ligaments, gingiva, and alveolar bone. Studies have reported increased local levels of pro-inflammatory cytokines, such as interleukin-1beta (IL-1beta), tumor necrosis factor (TNF), IL-6, IL-17, and IL-23, in patients with periodontitis. In experimental models of periodontitis, TNF and the IL-23/IL-17 axis play a pivotal role in disease pathogenesis. Inactivation of these pro-inflammatory pathways through neutralizing antibodies, genetic engineering or IL-10 function has been demonstrated to reduce disease activity. This review discusses the role of cytokines in gingivitis and periodontitis, with particular emphasis on their role in mediating inflammation and tissue destruction. It also explores new therapeutic interventions that offer potential for research and clinical therapy in these chronic inflammatory diseases.

Nrf2 Mitigates RANKL and M-CSF Induced Osteoclast Differentiation via ROS-Dependent Mechanisms

Nuclear factor-erythroid 2-related factor 2 (Nrf2) has been shown to be a negative regulator of osteoclast differentiation, but the precise mechanisms have not yet been established. We examined the precise roles of Nrf2 in regulating antioxidants and reactive oxygen species (ROS) levels, especially the cytoplasmic and mitochondrial ROS during osteoclastogenesis in vitro. In the current study, we found that the absence of Nrf2 promotes osteoclast differentiation in bone-marrow-derived macrophages (BMMs) and RAW 264.7 cells. The receptor activator of NF-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) significantly lowered the levels of Nrf2 and its downstream antioxidant enzymes at mRNA and/or protein levels during osteoclast differentiation in the BMMs of mice and RAW 264.7 mouse leukemic monocytes. Compared to the wild-type cells, Nrf2-deficient cells exhibited heightened sensitivity to both transient RANKL-induced cytoplasmic ROS and prolonged RANKL and M-CSF-induced cytoplasmic and mitochondrial ROS accumulation. Furthermore, exogenous antioxidant agents, including N-acetyl-cysteine (NAC), diphenyleneiodonium chloride (DPI), and mitoquinone mesylate (MitoQ), exhibited substantial capability to suppress the elevation of ROS levels during osteoclast differentiation induced by Nrf2 deficiency, and they consequently inhibited osteoclast differentiation augmented by the lack of Nrf2. The activation of phosphorylated c-FOS resulting from elevated ROS promoted osteoclast differentiation. The inhibition of c-FOS blocked osteoclast differentiation, which was elevated by Nrf2-deficiency. Taken together, these data reveal that Nrf2 effectively decreased the accumulation of intracellular ROS and the phosphorylation of c-FOS during osteoclastic differentiation by regulating antioxidant enzymes and subsequently inhibited RANKL-induced osteoclast differentiation.

Demographics, smoking status, and systemic health factors associated with apical periodontitis in a Brazilian rural population: a cross-sectional study

OBJECTIVE

To determine whether the systemic diseases diabetes mellitus (DM) and arterial hypertension (AH), and smoking status are associated with apical periodontitis (AP) in a representative rural population.

MATERIALS AND METHODS

Cross-sectional study using a representative sample of individuals obtained from a population-based epidemiological survey carried out in the rural area of the city of Rosário do Sul, RS, Brazil, from March 2015 to May 2016. Data were collected through structured questionnaires and clinical examination. Binary logistic regression analysis was performed to identify variables independently associated with AP.

RESULTS

Of the 584 individuals included in the study, 353 (60.4%) had AP. The presence of AP was independently associated with age ≥ 40 years (odds ratio [OR] = 1.867, 95% confidence interval [CI]: 1.193-2.923, p = 0.006), non-white ethnicity (OR = 1.509, 95% CI: 1.029-2.115, p = 0.035), active or former smoker (OR = 2.087, 95% CI: 1.241-3.510, p = 0.006) and DM or prediabetes (OR = 1.676, 95% CI: 1.150-2.443, p = 0.007).

CONCLUSION

The study identified significant associations between AP and demographics, smoking status, and systemic disease in a Brazilian rural population.

CLINICAL RELEVANCE

The study emphasized the significance of comprehending and managing associated factors in preventing and treating AP.

Effect of endodontic treatment on clinical outcome in type 2 diabetic patients with apical periodontitis

Background

Previous research has demonstrated that poor controlled diabetic showed higher prevalence of AP compared to well-controlled patients and endodontic treatment may improve metabolic control of patients with diabetes. The purpose of this trial was to clinically assess the effects of endodontic treatment on glycemic control in patients with type 2 diabetes mellitus (T2DM) and apical periodontitis (AP).

Study design

For present trial, AP + T2DM with patients insulin injection (Group1, G1,n = 65), AP + T2DM patients with hypoglycaemic agents (Group2, G2, n = 82), and AP patients without DM (Group3, G3, n = 86) were enrolled. After demographic characteristics and clinical examination were achieved, root canal treatment (RCT) was performed for each patient. Subjects were followed up at 2-week, 3- and 6-month. At each visit, blood samples were taken and clinical laboratory studies were performed. At 6-month follow-up, Periapical Index (PAI) score was used to assess the periapical status.

Results

A total of 237 subjects who met the including criteria were allocated in three groups and 223 subjects (94.1%) completed the treatments and the follow-up assessments. After treatment, taking PAI into consideration, both groups showed significant improvement of AP in each group (P < 0.05). Patients in G3 had a continued significant lower concentration of fasting plasma glucose (FPG) levels at follow-up (P < 0.05). A continued reduction of hemoglobin glycation (HbA1c) was observed in most of time points (P < 0.05). Throughout the trial, there are also significant changes in inflammatory factors in short-term.

Conclusion

Endodontic therapy improved AP healing, glycemic control and systemic inflammation in patients with T2DM and/or AP in each group. However, a continued reduction in inflammatory factors and decreasing of HbA1c in short-term could not be observed in this trial.

Evaluation of Receptor Activator of Nuclear Factor Kappa B Ligand, Osteoprotegerin, Osteopontin, and Tumor Necrosis Factor Alpha on Chronic Apical Periodontitis in Smokers

INTRODUCTION

Smoking can be considered a risk factor for chronic apical periodontitis (CAP). This study compared the immunoexpression of biomarkers receptor activator of nuclear factor kappa B ligand (RANKL), osteoprotegerin (OPG), osteopontin (OPN), and tumor necrosis factor alpha (TNF-α) in CAP in smokers and nonsmokers.

METHODS

Twelve smokers and 12 nonsmokers diagnosed with CAP and indicated for tooth extraction were selected. Exclusion factors were teeth with a diagnosis of root fracture, previous endodontic treatment, or endoperiodontal injury, in addition to individuals with systemic diseases, under 18 years of age, users of anti-inflammatory and/or antibiotics in the last 3 months, and drug users. Specimens were processed for histopathologic and immunohistochemical analysis.

RESULTS

Qualitative analysis of RANKL expression showed 66.66% weak/moderate and 33.33% strong in smokers and 100% weak/moderate in nonsmokers. OPG and OPN expressions were 100% negative to focal in the smoker group and 50% negative to focal and 50% weak/moderate in the nonsmoker group. TNF-α was 25% negative to focal and 75% weak/moderate in the smoker group and 33.33% negative to focal and 66.66% weak/moderate in the nonsmoker group. Quantitative analysis of the data using the Mann-Whitney U test showed that there was a significant difference in the immunoexpression of RANKL (P < .05), OPG (P < .05), and OPN (P < .05), but there was no statistical difference in the immunoexpression of TNF-α (P > .05) between the 2 groups.

CONCLUSIONS

These findings suggest that smoking is capable of altering the inflammatory response, influencing the evolution of CAP.