Chronic stress accelerates ligature-induced periodontitis by suppressing glucocorticoid receptor-α signaling

Preventive effects of melatonin on periodontal tissue destruction due to psychological stress in rats with experimentally induced periodontitis

OBJECTIVE AND BACKGROUND

Psychological stress is a potential modifiable environmental risk factor causally related to the exacerbation of periodontitis and other chronic inflammatory diseases. This animal study aimed to investigate comprehensively the preventive efficacy of systemic melatonin administration on the possible effects of restraint stress on the periodontal structures of rats with periodontitis.

METHODS

Forty-eight male Sprague Dawley rats were randomly divided into six groups: control, restraint stress (S), S-melatonin (S-Mel), experimental periodontitis (Ep), S-Ep, and S-Ep-Mel. Periodontitis was induced by placing a 3.0 silk suture in a sub-paramarginal position around the cervix of the right and left lower first molars of the rats and keeping the suture in place for 5 weeks. Restraint stress was applied simultaneously by ligation. Melatonin and carriers were administered to the control, S, Ep, and S-Ep groups intraperitoneally (10 mg/body weight/day, 14 days) starting on day 21 following ligation and subjection to restraint stress. An open field test was performed on all groups on day 35 of the study. Periodontal bone loss was measured via histological sections. Histomorphometric and immunohistochemical (RANKL and OPG) evaluations were performed on right mandibular tissue samples and biochemical (TOS (total oxidant status), TAS (total antioxidant status), OSI (oxidative stress index), IL-1β, IL-10, and IL-1β/IL-10) evaluations were performed on left mandibular tissue samples.

RESULTS

Melatonin significantly limited serum corticosterone elevation related to restraint stress (p < .05). Restraint stress aggravated alveolar bone loss in rats with periodontitis, while systemic melatonin administration significantly reduced stress-related periodontal bone loss. According to the biochemical analyses, melatonin significantly lowered IL-1β/IL-10, OSI (TOS/TAS), and RANKL/OPG rates, which were significantly elevated in the S-Ep group.

CONCLUSION

Melatonin can significantly prevent the limited destructive effects of stress on periodontal tissues by suppressing RANKL-related osteoclastogenesis and oxidative stress.

Yunvjian decoction attenuates lipopolysaccharide-induced periodontitis by suppressing NFκB/NLRP3/IL-1β pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Yunvjian decoction (YNJ) is a traditional Chinese herbal prescription that has been used in the clinical treatment of periodontitis. However, the underlying molecular mechanism of YNJ in the periodontitis treatment is not well understood.

AIM OF THE STUDY

The purpose of this study was to evaluate the therapeutic effects of YNJ against periodontitis and its underlying molecular mechanisms.

MATERIALS AND METHODS

Orthodontic ligation and lipopolysaccharide (LPS)-induced periodontitis rat model was established. YNJ groups were gavaged with YNJ decoction (5 g/kg/d or 10 g/kg/d) for four months. The rats in positive control group were gavaged with metronidazole (MDZ, 100 mg/kg/d) for four months. The maxilla was scanned by micro-computed tomography. The chemical compositions of YNJ were identified using ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry. The molecular mechanism of YNJ were predicted using network pharmacological analysis and validated using immune-staining and Western blot.

RESULTS

YNJ treatment decreased the distance between cementoenamel junction and alveolar bone crest on the sagittal slide of the periodontitis rats. Western blot showed YNJ downregulated the protein levels of the bone resorption marker (receptor activator of nuclear factor-κB ligand), while upregulated the levels of the bone formation markers (bone morphogenetic protein 2, runt-related transcription factor 2, alkaline phosphatase, and osteoprotegerin) in alveolar bone of the periodontitis rats. Hematoxylin and eosin, immunohistochemical staining, and Western blot analysis indicated that YNJ attenuated the inflammation and decreased the levels of interleukin-6 and tumor necrosis factor-α in the alveolar bone. In addition, a total of 61 compounds were identified from YNJ. Network pharmacology indicated that the nucleotide binding oligomerization domain-like receptor signaling pathway was the main pathway for YNJ in the treatment of periodontitis. The experiments confirmed that YNJ administration inhibited LPS induced-pyroptosis in alveolar bone through suppressing the phosphorylation of nuclear factor κB, reduced expression of NOD-like receptor family pyrin domain containing 3, and Caspase-1, subsequently suppressing the interleukin-1β secretion.

CONCLUSION

YNJ is an effective therapeutic strategy for periodontitis and acts by inhibiting pyroptosis and NFκB/NLRP3/IL-1β pathway in alveolar bone.

Impact of natural disaster on oral health: A scoping review

Natural disasters may affect oral health as a result of serious damage to social function and public health. However, no article has systematically summarized the impact of natural disasters on oral health. This review aimed to map the existing literature on the impact of natural disasters on oral health. Targeted literature was searched using PubMed, Web of Science, Cochrane Library, and CINAHL databases with the keywords "disaster" and "oral health." Eligibility criteria were established based on the Participant-Concept-Context model, and eligible studies were identified based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 flow diagram. Eight eligible studies related to earthquakes were included in this review. Of these, 7 studies were related to the 2011 Great East Japan Earthquake. Oral health status of victims of disaster was analyzed by assessing the following parameters: questionnaire surveys; examination for fungal infection; and analyses of the teeth, periodontal, and oral hygiene condition. Six studies suggested that natural disasters had a negative impact on oral health. Two studies could not determine the impact of natural disasters on oral health. Only 1 study analyzed the impact of disasters on oral health based on pre- and postdisaster surveys. This scoping review found that there was insufficient evidence to suggest a relationship between natural disasters and oral health and that there are biases in geographical areas and types of natural disasters in this research field. Further research is needed to promote evidence-based support by dental professionals during different disaster phases.

Regulatory effects of oral microbe on intestinal microbiota and the illness

Over the past decade, the association between oral health, intestinal microbiota, and systemic diseases has been further validated. Some oral microbial species have been isolated from pathological intestine mucosa or feces and identified as biomarkers for intestinal diseases. A small proportion of oral microbiome passes through or colonizes the lower gastrointestinal tract, even in healthy individuals. Opportunistic pathogens from the oral cavity may expand and participate in the occurrence and progression of intestinal diseases when the anatomical barrier is disrupted. These disruptors interact with the intestinal microbiota, disturbing indigenous microorganisms, and mucosal barriers through direct colonization, blood circulation, or derived metabolite pathways. While interacting with the host's immune system, oral-derived pathogens stimulate inflammation responses and guide the transition of the intestinal microenvironment from a healthy state to a pre-disease state. Therefore, the oral-gut microbiome axis sheds light on new clinical therapy options, and gastrointestinal tract ecology balance necessitates simultaneous consideration of both oral and gut microbiomes. This review summarizes possible routes of oral microbes entering the intestine and the effects of certain oral bacteria on intestinal microbiota and the host's immune responses.

Osteoporosis and Alveolar Bone Health in Periodontitis Niche: A Predisposing Factors-Centered Review

Periodontitis is a periodontal inflammatory condition that results from disrupted periodontal host-microbe homeostasis, manifested by the destruction of tooth-supporting structures, especially inflammatory alveolar bone loss. Osteoporosis is characterized by systemic deterioration of bone mass and microarchitecture. The roles of many systemic factors have been identified in the pathogenesis of osteoporosis, including endocrine change, metabolic disorders, health-impaired behaviors and mental stress. The prevalence rate of osteoporotic fracture is in sustained elevation in the past decades. Recent studies suggest that individuals with concomitant osteoporosis are more vulnerable to periodontal impairment. Current reviews of worse periodontal status in the context of osteoporosis are limited, mainly centering on the impacts of menopausal and diabetic osteoporosis on periodontitis. Herein, this review article makes an effort to provide a comprehensive view of the relationship between osteoporosis and periodontitis, with a focus on clarifying how those risk factors in osteoporotic populations modify the alveolar bone homeostasis in the periodontitis niche.

Profiling of plasma-derived exosomal RNA expression in patients with periodontitis: a pilot study

OBJECTIVE

This study aimed to profile differentially expressed (DE) exosomal RNAs in healthy subjects and periodontitis patients and compare their levels before and after treatment.

MATERIALS AND METHODS

Plasma samples from healthy subjects and patients with periodontitis (pre-/post-periodontal treatment) were collected for this case-control study. After isolation of exosomes from the plasma, the RNA was extracted and small RNA sequencing was performed (3 healthy samples, 4 pre-treatment samples, and 5 post-treatment samples). Two-way analyses were conducted according to the treatment status in the periodontitis group, unpaired analysis (grouping as pre-/post-treatment) and paired analysis (matching pre- and post-treatment in the same subject). The DE exosomal RNAs were screened by sequencing and visualized using the R software. Gene Ontology analysis was performed, and target genes were identified.

RESULTS

In both paired and unpaired analyses, two DE microRNAs (DEmiRs; miR-1304-3p and miR-200c-3p) and two DE small nucleolar RNAs (DEsnoRs; SNORD57 and SNODB1771) were common, and they were found to be downregulated during periodontitis and recovered to healthy levels after treatment. The top three target genes (NR3C1, GPR158, and CNN3) commonly regulated by DEmiRs were identified.

CONCLUSIONS

Plasma-derived exosomal miRs (miR-1304-3p and miR-200c-3p) and snoRs (SNORD57 and SNODB1771) could be valuable biomarkers for periodontitis.

CLINICAL PECULIARITIES OF WOUND HEALING AFTER SURGICAL TREATMENT OF PATIENTS WITH GENERALIZED PERIODONTITIS ACCOMPANIED BY DIFFERENT TYPES OF REACTIVITY OF THE BODY

OBJECTIVE

The aim: To study the features of clinical wound healing (intensity and duration of inflammatory reaction) after the indications for patients with generalized periodontitis II, III degrees of severity of patch surgery accompanied by normo-, hyper- and hyporeactivity of the body.

PATIENTS AND METHODS

Materials and methods: 216 people aged 45 between 55 years with a diagnosis of generalized periodontitis of II, III degree of severity, chronic course were examined. Depending on the condition of reactivity of the organism, the patients were divided into three groups: the first one consisted of people with normoreaction; the second group included patients with hyperreaction; the third group was made up by people with hyporeaction. The patients after the initial therapy, underwent patch surgery. Initially, on the 2nd, 4th, 6th and 9th day after the operation, the clinical examination of the periodontal tissues (examination, hygienic and periodontal indices) was performed. Statistical processing of the obtained digital data was performed using the computer program Statistica 8.0.

RESULTS

Results: Normoreactivity of the body determines the normal time of wound healing after patch surgery, which on the 9th day is characterized by the clinical condition of the gingival mucosa, which corresponds to the concept "healthy" for 98% of patients. In case of hyperreactivity of the organism slowing down of processes of wound healing for 3-4 days in comparison with the time which is typical for normoreactivity with dynamics of the indices which specifies long intensive character of inflammatory reaction in the postoperative period has been observed. In case of hyporeactivity of the body as well as in case of hyperreaction, there was a slowdown in wound healing for 3-4 days compared with normoreactivity with the dynamics of indices that showed slow sluggish nature of the inflammatory reaction in the postoperative period.

CONCLUSION

Conclusions: Correction of altered parameters in patients with generalized periodontitis accompanied by impaired (hyper- and hypo-) reactivity of the body with bringing them to values which are typical for normoreactivity is considered to be a condition for optimizing mucosal wound healing after surgery and further stabilization of the periodontal tissues.

Moringa oleifera Lam. leaf extract safely inhibits periodontitis by regulating the expression of p38α/MAPK14-OPG/RANKL

Periodontitis is a chronic disease clinically defined by loss of alveolar bone and connective tissue degeneration. Although Moringa oleifera Lam. (MO), a tree belonging to the Moringacea family, is widely used as an anti-inflammatory agent, its effect on periodontitis is still unclear. In this work, the phenol compounds in MO leaf extract (MOL) were identified by UPLC-ESI-MS/MS, and the anti-periodontitis effects and mechanism of MOL were predicted using network pharmacology and molecular docking. Moreover, the cytotoxic, antioxidant, and anti-periodontitis properties of MOL were confirmed in vivo and in vitro. In total, 88 phenolic compounds and 234 potential MOL periodontitis targets were screened, involving 2916 biological processes (BP). The p38α MAPK (MAPK14) pathway and OPG/RANKL complex were predicted to be involved in the process of molecular docking. Furthermore, experimental validation suggested that MOL significantly ameliorated inflammation and reduced alveolar bone resorption. The OPG/RANKL ratio was regulated through the inhibition of MAPK14, and the anti-periodontitis effect was realized by the antioxidant properties of MOL. Hematoxylin and eosin (H&E) staining of rat vital organs and the survival rate of RAW 264.7 cells confirmed the safety of MOL. The present study provides valuable insights into how MOL reduces inflammation and alveolar bone resorption associated with periodontitis. In conclusion, MOL safely inhibits chronic periodontitis highly likely by regulating the expression of p38α/MAPK14-OPG/RANKL. Network pharmacology coupled with experimental validation is an effective way to find new drugs in the future. DATA AVAILABILITY STATEMENT: The original data presented in the study are included in the article. Further inquiries can be directed to the corresponding authors.

The influence of adrenergic blockade in rats with apical periodontitis under chronic stress conditions

OBJECTIVE

To investigate the influence of chronic stress and adrenergic blockade in a rat model of apical periodontitis.

METHODS

Thirty-two Wistar rats were submitted to an animal model of periapical lesion and randomly divided into 4 groups (n = 8): no stress (NS); stress + saline solution (SS); stress + β-adrenergic blocker (Sβ); stress + α-adrenergic blocker (Sα). The SS, Sβ and Sα groups were submitted to an animal model of chronic stress for 28 days and received daily injections of saline solution, propranolol (β adrenergic blocker) and phentolamine (α adrenergic blocker), respectively. After 28 days the animals were euthanized and the following analyses were carried out: a) serum corticosterone levels through Radioimmunoassay; b) measurement of serum levels of IL-1B, IL-6, IL-10 and IL-17 by enzyme-linked immunosorbent assay (ELISA); c) volume of periapical bone resorption by micro-computed tomography; d) histomorphometric analysis by staining with hematoxylin and eosin; e) expression of β-AR, α-AR, receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) by immunohistochemistry; f) tartrate-resistant acid phosphatase (TRAP) staining; g) ex-vivo cytokine release followed by the stimulation with LPS in superfusion system, by ELISA.

RESULTS

SS group displayed significantly higher corticosterone levels than NS group (non-stressed). Higher IL-1β serum level was observed in the NS group (p < .05); compared to all stressed groups. Other cytokines were present in similar amounts in the serum of all groups. All groups presented similar periapical lesions. All groups presented moderate inflammatory infiltrate, without statistically significant differences between them. No differences were observed regarding β-AR, α-AR, Rank-L and OPG expression. The number of TRAP-positive cells was significantly decreased in the groups that received daily injections of adrenergic blockers. The IL-1β release followed LPS stimulation was significantly suppressed when the superfusion media contained propranolol (p < .05). Perfusion containing phentolamine induced a greater release of IL-10. TGF-β was significantly suppressed by phentolamine perfusion in the NS group (p < .05).

CONCLUSIONS

Chronic stress can significantly change the inflammatory cytokines release. Rank-L/OPG system and periapical lesion volume were not affected following the current method applied. The administration of adrenergic blockers was not able to modulate the inflammatory response but presented effectivity in reducing the number of osteoclasts in the periapical region.

Anti-inflammatory effect of paeoniflorin combined with baicalin in oral inflammatory diseases

OBJECTIVE

There are challenges in the treatment of chronic inflammatory diseases of oral mucosa. Both paeoniflorin (PF) and baicalin (BAI) exert anti-inflammatory effects, but the mechanism underlying their combined effects is still unclear. Here, we explored the anti-inflammatory function of the PF-BAI combination in the oral inflammatory response.

MATERIALS AND METHODS

The CCK-8 assay was used to determine the proliferative capacity of HOKs with PF and BAI. Enzyme-linked immunosorbent (ELISA), Western blotting, reverse transcription polymerase chain reaction, and confocal immunofluorescence were performed to study the anti-inflammatory effects of PF-BAI in LPS-stimulated human oral keratinocytes (HOKs). Immunohistochemistry and ELISA were performed to detect the levels of NF-κB p65, IKKα and IL-6, TNF-α in OLP and healthy tissues.

RESULTS

Compared to PF or BAI alone, the combination of PF-BAI at 5 µg/ml downregulated secretion of inflammatory cytokines more effectively (p < .05). Combined PF-BAI decreased NF-κB p65 and IκBα protein phosphorylation, leading to reduce nuclear translocation of NF-κB p65. Higher expression of TNF-α, IL-6, NF-κB p65, and IKKα were observed in OLP than in HC tissues (p < .01).

CONCLUSION

The optimal combination concentration of PF and BAI at 5 µg/ml may have a positive effect on the treatment of oral inflammatory diseases, providing a novel therapeutic approach.

Periodontitis as another comorbidity associated with psoriasis: A case-control study

BACKGROUND

The association between periodontitis and immuno-mediated inflammatory diseases has been widely studied and recognized each more over the past few years. The aim of this study was to evaluate the potential association between psoriasis and periodontitis, as well as the influence of risk variables in this association.

METHODS

This case-control study included 756 individuals, 397 with psoriasis, and 359 controls. A full-mouth periodontal examination was performed, recording therefore plaque index, probing depth, clinical attachment level, and bleeding on probing. The influence of risk variables was tested by univariate analysis and multivariate logistic regression.

RESULTS

A high prevalence of periodontitis was observed among cases (46.1%) when compared to controls (33.1%). Individuals with psoriasis presented a 1.72 higher chance of having periodontitis than controls (OR = 1.72; 95% CI 1.28-2.32; p < 0.001) in the univariate analysis, but with no significance in the multivariate model. The prevalence of periodontitis increased significantly according to the severity of psoriasis [mild form (44.4%); moderate (46.3%); and advanced (47.1%)] when compared to the control group (33.1%). The final multivariate logistic model showed that the number of teeth (OR = 1.08; 95% CI 1.01-1.14; p = 0.018), smoking (OR = 1.91; 95% CI 1.19-3.07; p = 0.008), and body mass index (OR = 1.13; 95% CI 1.11-1.16; p < 0.001) remained significantly associated with the occurrence of periodontitis.

CONCLUSIONS

The prevalence of periodontitis was higher in individuals with psoriasis than in controls. Severity of psoriasis also presented a strong relationship with all periodontal clinical parameters.

Protective effect of casuarinin against glutamate-induced apoptosis in HT22 cells through inhibition of oxidative stress-mediated MAPK phosphorylation

Glutamate is the major excitatory neurotransmitter in the central nervous system and is involved in oxidative stress during neurodegeneration. In the present study, casuarinin prevented glutamate-induced HT22 murine hippocampal neuronal cell death by inhibiting intracellular reactive oxygen species (ROS) production. Moreover, casuarinin reduced chromatin condensation and annexin-V-positive cell production induced by glutamate. We also confirmed the underlying protective mechanism of casuarinin against glutamate-induced neurotoxicity. Glutamate markedly increased the phosphorylation of extracellular signal regulated kinase (ERK)-1/2 and p38, which are crucial in oxidative stress-mediated neuronal cell death. Conversely, treatment with casuarinin diminished the phosphorylation of ERK1/2 and P38. In conclusion, the results of this study suggest that casuarinin, obtained from natural products, acts as potent neuroprotective agent by suppressing glutamate-mediated apoptosis through the inhibition of ROS production and activation of the mitogen activated protein kinase (MAPK) pathway. Thus, casuarinin can be a potential therapeutic agent in the treatment of neurodegenerative diseases.

Glucocorticoid receptors: finding the middle ground

Glucocorticoids (GCs; referred to clinically as corticosteroids) are steroid hormones with potent anti-inflammatory and immune modulatory profiles. Depending on the context, these hormones can also mediate pro-inflammatory activities, thereby serving as primers of the immune system. Their target receptor, the GC receptor (GR), is a multi-tasking transcription factor, changing its role and function depending on cellular and organismal needs. To get a clearer idea of how to improve the safety profile of GCs, recent studies have investigated the complex mechanisms underlying GR functions. One of the key findings includes both pro- and anti-inflammatory roles of GR, and a future challenge will be to understand how such paradoxical findings can be reconciled and how GR ultimately shifts the balance to a net anti-inflammatory profile. As such, there is consensus that GR deserves a second life as a drug target, with either refined classic GCs or a novel generation of nonsteroidal GR-targeting molecules, to meet the increasing clinical needs of today to treat inflammation and cancer.