Role of interleukin-1 and inflammasomes in oral disease

Interaction of the Systemic Inflammatory State, Inflammatory Mediators, and the Oral Microbiome

Humans are biological units that host numerous microbial symbionts and their genomes, which together form a superorganism or holobiont. Changes in the balance of the oral ecosystem can have consequences for both general and oral health, such as cavities, gingivitis, and periodontitis. Periodontitis is initiated by a synergistic and dysbiotic microbial community that causes local inflammation and destruction of the tooth's supporting tissues, potentially leading to systemic inflammation. This inflammation caused by periodontal disease has been associated with various systemic alterations, and the immune system is largely responsible for the body's exacerbated response, which can induce and exacerbate chronic conditions. Studies indicate that subgingival microorganisms found in periodontitis reach the bloodstream and are distributed throughout the body and, therefore, can be found in distant tissues and organs. Among all diseases associated with periodontal disease, diabetes mellitus presents the strongest and most elucidated link, and its bidirectional relationship has already been demonstrated. Chronic hyperglycemia favors the worsening of periodontal parameters, while the aggravation of periodontal parameters can promote an increase in glycemic indexes. Other systemic diseases have been related to periodontitis, such as Alzheimer's, chronic kidney disease, atherosclerosis, and respiratory diseases. The importance of periodontal control may suggest a reduction in the chances of developing chronic inflammatory diseases because these two alterations often share inflammatory pathways and, for this reason, may influence each other.

Clinical Study on the Implications of Immunological Markers in the Diagnosis of Periodontitis in People with Diabetes Mellitus

The basic idea from which the working hypothesis for this study started is the fact that the only systemic disease today that is clearly linked to periodontal disease by biochemical mechanisms is diabetes mellitus, as well as the clinical finding that diabetes causes a number of specific periodontal changes. Highlighting the biochemical markers of inflammation during periodontal disease in patients diagnosed with type 2 diabetes is the main aim of the study. To achieve this objective, we used the human ELISA kit from Boster Biological Technology Co., Ltd. (Pleasanton, CA, USA), for the detection of IL-1β, IL-4, IL-8 and TNF-α. The data analysis shows that plasma levels of these cytokines are associated with the progression of periodontitis. In conclusion, we can state that the involvement of immunological markers is evident in the pathogenesis of periodontal disease.

Changes in the level of cytokines in the saliva of hypertensive patients with chronic periodontitis after scaling and root planning

INTRODUCTION

Cytokines have a key role in the pathogenesis of both hypertension and periodontitis. Salivary diagnosis is a promising field with numerous clinical applications. Since limited studies have been carried out on how salivary inflammatory cytokines can be determined and how well periodontal disease and hypertension might react to scaling and root planning (SRP). The goal of this study was to identify the pattern of changes in salivary inflammatory cytokines in chronic periodontitis subjects with hypertension after nonsurgical periodontal therapy.

METHODS

It included observational trial recruited 94 chronic periodontitis patients, 44 of whom had hypertension. All subjects have undergone non- surgical periodontal treatment. The clinical periodontal parameters included gingival index (GI), plaque index (PI), and probing of pocket depth (PPD). Unstimulated saliva was collected to determine the inflammatory biomarkers (using a commercial Elisa kit) both before and after SRP RESULTS: In comparison to non-hypertensive participants, the periodontal PPD was significantly higher in hypertensive subjects. All clinical parameters in the first examination, except for PI, were significantly higher in hypertensive than in non-hypertensive subjects. Plaque Index, GI, and PPD parameters at first visit and after finishing treatment positively correlated with salivary IL-1β, excluding pretreatment GI. The current results demonstrate the presence of a positive correlation between diastolic blood pressure and TNF (r = 0.330 and P = 0.029). All patients enrolled in this study showed a significant increase in the salivary levels of IL-4 after SRP.

CONCLUSIONS

The current study offer important and valuable information concerning the practical application of pro-inflammatory and anti-inflammatory cytokines as useful biomarkers and indicators for determining the outcome of SRP and progression of chronic periodontitis in patients with hypertension.

Evaluation of periodontal status and cytokine response in children with familial Mediterranean fever or systemic juvenile idiopathic arthritis

OBJECTIVES

Familial Mediterranean fever (FMF) and systemic juvenile idiopathic arthritis (sJIA) are chronic inflammatory diseases and anti-inflammatory agents are used in their treatment. This study evaluates the periodontal status and cytokine response in pediatric patients with FMF or sJIA.

MATERIALS AND METHODS

Forty-eight FMF/sJIA patients were under treatment/control and in attack-free period; 20 systemically healthy children participated in the study. FMF/sJIA patients were divided into two subgroups based on the treatment they received: receiving anti-IL-1 therapy (anti-IL-1 ( +)) and not receiving anti-IL-1 therapy (anti-IL-1 ( -)). The clinical periodontal indices were recorded. Gingival crevicular fluid (GCF) and serum samples were collected. Cytokine levels (IL-1β, IL-1α, TNF-α, IL-6, IL-8, IL-10, IL-17, IL-33) in GCF and serum were measured using ELISA kits.

RESULTS

There was no significant difference between the groups in terms of GCF IL-1β and IL-1α levels although, BoP and GI were significantly lower in the anti-IL-1 ( +) group compared to the control group. GCF IL-10 level was higher in the anti-IL-1 ( -) group than in the control group; GCF IL-8 levels were lower in both FMF/sJIA subgroups versus controls. There was no significant difference between serum cytokine levels of FMF/sJIA subgroups.

CONCLUSIONS

Considering the significant decrease in GI, BoP, and GCF IL-8 levels in the anti-IL-1 ( +) group, it can be concluded that anti-IL-1 medications may suppress periodontal inflammation clinically and immunologically.

CLINICAL RELEVANCE

Anti-IL agents are not currently used in periodontal therapy. However, this study demonstrated the positive effect of anti-IL-1 medications on periodontal inflammation in pediatric patients with FMF or sJIA.

Anti-inflammatory Effect by Cloves Treatment in LPS-induced RAW264.7 Cells

Background:

Cloves mean the dried flower bud harvested from a tree of Syzygium aromaticum L. (SA).

Objectives:

The current study was to identify the anti-inflammatory effects of SA on lipopolysaccharide (LPS) (0.2 µg/mL)-treated RAW264.7 cells.

Materials and Methods:

WST-8 cell proliferation assay kit (WST-8) and lactate dehydrogenase (LDH) assays were completed to observe cell proliferation and cytotoxicity effects of SA. Other biochemical analyses analyzed releases of nitric oxide (NO) and the production of dichlorofluorescin diacetate (DCF-DA). Besides, inflammation-related factors and Sirt1 were carried out through immunohistochemistry (IHC) and immunofluorescence (IF).

Results:

LPS exposure not only caused abnormal elevations of both NO and reactive oxygen species (ROS) secretions, but also markedly increased inflammation-related proteins including inducible NO synthase (iNOS), cluster of differentiation (CD) 14, and toll-like receptor (TLR) 4, and nuclear factor-κB (NF-κB). The above-listed alterations were notably attenuated by SA pretreatment in a dose-dependent manner. We further figured out that, SA particularly activated AMPKα/ Sirt1 signaling pathway. Furthermore, SA dramatically inhibited interleukin (IL)-1β production, which was mediated by NLR family Pyrin domain containing (NLRP) 3 mediated inflammasome signaling pathway.

Conclusion:

SA inhibits LPS-induced inflammation in RAW264.7 cells via the TRL4/CD14/NF-κB pathway and it can lead to the reduction of IL-1β release by the inhibition of NLRP3 inflammasome. Such an anti-inflammatory effect was closely related to AMPKα/Sirt1 activation. Taken together, the findings of this study support both the inhibition of NLRP3 inflammasome and activation of Sirt1 can alleviate inflammation.

Potential Impact of Prosthetic Biomaterials on the Periodontium: A Comprehensive Review

The success of a prosthetic treatment is closely related to the periodontal health of the individual. The aim of this article was to review and present the importance of prosthetic restorative materials on the condition of the periodontium, the changes that occur in the composition of the subgingival microbiota and the levels of inflammatory markers in gingival crevicular fluid. Articles on the influence of different prosthetic restorative materials on subgingival microbiota and proinflammatory cytokines were searched for using the keywords "prosthetic biomaterials", "fixed prosthesis", "periodontal health", "subgingival microbiota", "periodontal biomarkers" and "gingival crevicular fluid" in PubMed/Medline, Science Direct, Scopus and Google Scholar. The type of material used for prosthesis fabrication together with poor marginal and internal fit can result in changes in the composition of the subgingival microbiota, as well as increased accumulation and retention of dentobacterial plaque, thus favoring the development of periodontal disease and prosthetic treatment failure. Biological markers have helped to understand the inflammatory response of different prosthetic materials on periodontal tissues with the main purpose of improving their clinical application in patients who need them. Metal-free ceramic prostheses induce a lower inflammatory response regardless of the fabrication method; however, the use of CAD/CAM systems is recommended for their fabrication. In addition, it is presumed that metal-ceramic prostheses cause changes in the composition of the subgingival microbiota producing a more dysbiotic biofilm with a higher prevalence of periodontopathogenic bacteria, which may further favor periodontal deterioration.

Activation and Function of NLRP3 Inflammasome in Bone and Joint-Related Diseases

Inflammation is a pivotal response to a variety of stimuli, and inflammatory molecules such as cytokines have central roles in the pathogenesis of various diseases, including bone and joint diseases. Proinflammatory cytokines are mainly produced by immune cells and mediate inflammatory and innate immune responses. Additionally, proinflammatory cytokines accelerate bone resorption and cartilage destruction, resulting in the destruction of bone and joint tissues. Thus, proinflammatory cytokines are involved in regulating the pathogenesis of bone and joint diseases. Interleukin (IL)-1 is a representative inflammatory cytokine that strongly promotes bone and cartilage destruction, and elucidating the regulation of IL-1 will advance our understanding of the onset and progression of bone and joint diseases. IL-1 has two isoforms, IL-1α and IL-1β. Both isoforms signal through the same IL-1 receptor type 1, but the activation mechanisms are completely different. In particular, IL-1β is tightly regulated by protein complexes termed inflammasomes. Recent research using innovative technologies has led to a series of discoveries about inflammasomes. This review highlights the current understanding of the activation and function of the NLRP3 (NOD-like receptor family, pyrin domain-containing 3) inflammasome in bone and joint diseases.

Aggregatibacter actinomycetemcomitans Leukotoxin Activates the NLRP3 Inflammasome and Cell-to-Cell Communication

Carriers of highly leukotoxic genotypes of Aggregatibacter actinomycetemcomitans are at high risk for rapid degradation of tooth-supporting tissues. The leukotoxin (LtxA) expressed by this bacterium induces a rapid pro-inflammatory response in leukocytes that results in cell death. The aim of the present study was to increase the understanding of LtxA-induced leukocyte activation mechanisms and of possible associated osteoclast differentiation. The effect of LtxA on activation of the inflammasome complex was studied in THP-1 wild type and in NLRP3- and ASC knockout cells. Cell-to-cell communication was assessed by fluorescent parachute assays, and THP-1 differentiation into osteoclast-like cells was investigated microscopically. The results showed that LtxA induced inflammatory cell death, which involved activation of the NLRP3 inflammasome and gap junction cell-to-cell communication. THP-1 cells treated with lipopolysaccharide (LPS) and LtxA together differentiated into an osteoclast-like phenotype. Here, LPS prevented LtxA-mediated cell death but failed to induce osteoclast differentiation on its own. However, pit formation was not significantly enhanced by LtxA. We conclude that A. actinomycetemcomitans leukotoxicity mediates activation of the NLRP3 inflammasome and cell-to-cell communication in the induced pro-inflammatory cell death. In addition, LtxA stimulated differentiation towards osteoclasts-like cells in LPS-treated THP-1 cells.

Pivotal Role of Corneal Fibroblasts in Progression to Corneal Ulcer in Bacterial Keratitis

The shape and transparency of the cornea are essential for clear vision. However, its location at the ocular surface renders the cornea vulnerable to pathogenic microorganisms in the external environment. Pseudomonas aeruginosa and Staphylococcus aureus are two such microorganisms and are responsible for most cases of bacterial keratitis. The development of antimicrobial agents has allowed the successful treatment of bacterial keratitis if the infection is diagnosed promptly. However, no effective medical treatment is available after progression to corneal ulcer, which is characterized by excessive degradation of collagen in the corneal stroma and can lead to corneal perforation and corneal blindness. This collagen degradation is mediated by both infecting bacteria and corneal fibroblasts themselves, with a urokinase-type plasminogen activator (uPA)-plasmin-matrix metalloproteinase (MMP) cascade playing a central role in collagen destruction by the host cells. Bacterial factors stimulate the production by corneal fibroblasts of both uPA and pro-MMPs, released uPA mediates the conversion of plasminogen in the extracellular environment to plasmin, and plasmin mediates the conversion of secreted pro-MMPs to the active form of these enzymes, which then degrade stromal collagen. Bacterial factors also stimulate expression by corneal fibroblasts of the chemokine interleukin-8 and the adhesion molecule ICAM-1, both of which contribute to recruitment and activation of polymorphonuclear neutrophils, and these cells then further stimulate corneal fibroblasts via the secretion of interleukin-1. At this stage of the disease, bacteria are no longer necessary for collagen degradation. In this review, we discuss the pivotal role of corneal fibroblasts in corneal ulcer associated with infection by P. aeruginosa or S. aureus as well as the development of potential new modes of treatment for this condition.

Genetic Susceptibility to Periodontal Disease in Down Syndrome: A Case-Control Study

Severe periodontitis is prevalent in Down syndrome (DS). This study aimed to identify genetic variations associated with periodontitis in individuals with DS. The study group was distributed into DS patients with periodontitis (n = 50) and DS patients with healthy periodontium (n = 36). All samples were genotyped with the “Axiom Spanish Biobank” array, which contains 757,836 markers. An association analysis at the individual marker level using logistic regression, as well as at the gene level applying the sequence kernel association test (SKAT) was performed. The most significant genes were included in a pathway analysis using the free DAVID software. C12orf74 (rs4315121, p = 9.85 × 10⁻⁵, OR = 8.84), LOC101930064 (rs4814890, p = 9.61 × 10⁻⁵, OR = 0.13), KBTBD12 (rs1549874, p = 8.27 × 10⁻⁵, OR = 0.08), PIWIL1 (rs11060842, p = 7.82 × 10⁻⁵, OR = 9.05) and C16orf82 (rs62030877, p = 8.92 × 10⁻⁵, OR = 0.14) showed a higher probability in the individual analysis. The analysis at the gene level highlighted PIWIL, MIR9-2, LHCGR, TPR and BCR. At the signaling pathway level, PI3K-Akt, long-term depression and FoxO achieved nominal significance (p = 1.3 × 10⁻², p = 5.1 × 10⁻³, p = 1.2 × 10⁻², respectively). In summary, various metabolic pathways are involved in the pathogenesis of periodontitis in DS, including PI3K-Akt, which regulates cell proliferation and inflammatory response.

Association of Interleukin-1α Functional Polymorphism with Risk of Chronic Periodontitis in Han Chinese Population

Chronic periodontitis (CP) is a common inflammatory illness affecting a large proportion of humans. Genetic factors are thought to play important roles in its onset and development. A functional polymorphism (rs1800587) in the promoter of the interleukin-1α gene (−889 C/T) has been found to confer risk of CP primarily in Europeans, but the association between this variant and CP in the Chinese population remains less conclusive. In the current study, we aimed to investigate the association between rs1800587 and CP in case-control samples of Han Chinese origin. A total of 1,777 study subjects, including 884 CP patients and 893 healthy controls, were collected. Genotyping of rs1800587 was performed using the SNAPSHOT method, and statistical analyses were conducted to evaluate the association between rs1800587 and CP. In our sample, rs1800587 was significantly associated with the onset of CP (additive model, T-allele vs. C-allele, p = 0.00359, odds ratio = 1.446, 95% confidence intervals (CIs) = 1.127–1.855; dominant model, (TT + TC) vs. CC, p = 0.00250, odds ratio = 1.502, 95% CIs = 1.152–1.957; overdominant model, TC vs. (TT + CC), p = 0.00264, odds ratio = 1.508, 95% CIs = 1.152–1.976). The T-allele and [TC] genotypes of rs1800587 were significantly overrepresented in CP patients compared with controls. Our data suggest that rs1800587 of IL-1α is significantly associated with the risk of CP in Han Chinese subjects, further confirming its possible involvement in the disease.

Oral biosciences: The annual review 2020

BACKGROUND

The Journal of Oral Biosciences is devoted to the advancement and dissemination of fundamental knowledge concerning every aspect of oral biosciences.

HIGHLIGHT

This review featured the review articles in the fields of "Microbiology," "Palate," "Stem Cells," "Mucosal Diseases," "Bone Cell Biology," "MicroRNAs," "TRPV1 Cation Channels," and "Interleukins" in addition to the review article by prize-winners of the "Rising Members Award" ("DKK3 expression and function in head and neck squamous cell carcinoma and other cancers"), presented by the Japanese Association for Oral Biology.

CONCLUSION

These reviews in the Journal of Oral Biosciences have inspired the readers of the journal to broaden their knowledge regarding the various aspects of oral biosciences. The current editorial review introduces these exciting review articles.