Mast Cell Cytokines in Acute and Chronic Gingival Tissue Inflammation: Role of IL-33 and IL-37

Inflammation-related collagen fibril destruction contributes to temporomandibular joint disc displacement via NF-κB activation

Temporomandibular joint (TMJ) disc displacement is one of the most significant subtypes of temporomandibular joint disorders, but its etiology and mechanism are poorly understood. In this study, we elucidated the mechanisms by which destruction of inflamed collagen fibrils induces alterations in the mechanical properties and positioning of the TMJ disc. By constructing a rat model of TMJ arthritis, we observed anteriorly dislocated TMJ discs with aggravated deformity in vivo from five weeks to six months after a local injection of Freund's complete adjuvant. By mimicking inflammatory conditions with interleukin-1 beta in vitro, we observed enhanced expression of collagen-synthesis markers in primary TMJ disc cells cultured in a conventional two-dimensional environment. In contrast, three-dimensional (3D)-cultivated disc cell sheets demonstrated the disordered assembly of inflamed collagen fibrils, inappropriate arrangement, and decreased Young's modulus. Mechanistically, inflammation-related activation of the nuclear factor kappa-B (NF-κB) pathway occurs during the progression of TMJ arthritis. NF-κB inhibition reduced the collagen fibril destruction in the inflamed disc cell sheets in vitro, and early NF-κB blockade alleviated collagen degeneration and dislocation of the TMJ discs in vivo. Therefore, the NF-κB pathway participates in the collagen remodeling in inflamed TMJ discs, offering a potential therapeutic target for disc displacement.

Identification and Validation of Ferritinophagy-Related Biomarkers in Periodontitis

OBJECTIVE

While ferritinophagy is believed to play a significant role in the development of periodontitis, the exact mechanisms remain unclear. This study aimed to investigate the biomarkers associated with ferritinophagy in periodontitis using transcriptomic data.

METHODS

Two periodontitis-related datasets from Gene Expression Omnibus, GSE10334, and GSE16134, served as the training and validation cohorts, respectively. Additionally, 36 ferritinophagy-related genes (FRGs) were obtained from the GeneCards database. We compared the expression differences of FRGs between the periodontitis and control groups, identifying the different FRGs as candidates. Weighted gene coexpression network analysis (WGCNA) was applied to capture the key modules and modular genes related to periodontitis, utilizing the candidate FRG scores as trait. Then we intersected these with key module genes to identify differentially expressed FRGs. Hub genes were filtered using a protein-protein interaction network. Ultimately, biomarkers were acquired through machine learning, receiver operating characteristic curves, and expression levels. In addition, biomarker-associated immune cells and functional pathways were analysed to predict the upstream regulatory molecules.

RESULTS

In total, 18 candidate FRGs showed significant differences between the periodontitis and control groups, and from the protein-protein interaction network, eight hub genes were identified among the 175 differentially expressed FRGs by analysing 1096 differentially expressed genes and 4479 key modular genes. Eventually, ALDH2, diazepam binding inhibitor, HMGCR, OXCT1, and ACAT2 were identified as potential biomarkers through machine learning algorithms, receiver operating characteristic curve analysis, and gene expression assessments. In addition, resting dendritic cells, mast cells, and follicular helper T cells were positively correlated with the five biomarkers (Cor > 0.3 and P < .05). All five biomarkers are involved in the translation initiation pathway, including transcription factors like KLF5 and microRNAs such as hsa-miR-495-3p and hsa-miR-27a-3p. Reverse transcription-quantitative polymerase chain reaction analysis showed that all biomarkers were expressed at low levels in the periodontitis group. However, the differences in expression levels for OXCT1 and ACAT2 between groups were not statistically significant.

CONCLUSIONS

A total of five ferritinophagy-related biomarkers - ALDH2, diazepam binding inhibitor, HMGCR, OXCT1, and ACAT2 - were screened to explore new treatment options for periodontitis.

Expression of IL-33 in subjects with periodontitis: a systematic review and meta-analysis

BACKGROUND

Activation of the IL-33/ST2 axis leads to the production of proinflammatory cytokines and thus to the triggering of osteoclastogenesis, which is why it plays an important role in the immunopathogenesis of periodontitis. The aim of this study was to compare IL-33 levels in serum, plasma, saliva and gingival crevicular fluid (GCF) of subjects with chronic periodontitis (CP) in comparison with the control group (CG).

METHODS

This systematic review and meta-analysis followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) and was registered in the Open Science Framework (OSF): https://doi.org/10.17605/OSF.IO/YHUWA . Six electronic databases were used for study identification; PubMed, Google Scholar, ScienceDirect, Web of Science, Scopus and Dentistry & Oral Sciences Source from March 10, 2012 to April 30, 2024. The Joanna Briggs Institute (JBI) tool was used to assess the quality of the included cross-sectional articles and clinical trials.

RESULTS

Of the 949 articles identified, 14 were included according to the inclusion and exclusion criteria. The total number of individuals studied in the included investigations was 814 of whom 445 had CP and 369 were healthy. The reported age range was from 20 to 50 years, with a mean age ± standard deviation of 40.29 ± 7.83 years. Four hundred and twenty-six (52%) patients were men and 388 (48%) were women. Meta-analysis revealed that there is an increase in IL-33 levels in plasma, saliva and GCF of subjects with CP compared to CG (p = * < 0.05).

CONCLUSIONS

This study found a significant increase in IL-33 levels in different biological samples (plasma, saliva and GCF) of individuals with CP compared to CG, thus IL-33 has potential to be a biomarker in the diagnosis of periodontitis.

Novel Insights into Amlodipine-Induced Gingival Enlargement: A Clinical and Molecular Perspective

This study aimed to identify risk factors for amlodipine-induced gingival enlargement, assess quality of life, and analyze gingival tissue. This cross-sectional study involved hypertensive patients on amlodipine, divided into groups with and without gingival enlargement. Assessments included sociodemographic data, clinical evaluations, and clinical parameters. Quality of life was assessed using OHIP-14 and WB-HRQoL scales. Gingival tissue samples were analyzed for oxidative status and key molecules using RT-PCR and colorimetric assays. The study included 32 patients with no significant sociodemographic differences between groups (p > 0.05). Patients with gingival enlargement had higher systolic blood pressure (139.63 ± 10.743 vs. 128.38 ± 7.249, p = 0.028) and higher OHIP-14 scores. The RT-PCR analysis showed significant differences in IL-6, TNF-α, IL-33, ST2, TGF-β1, FGF-2, CTGF, VEGF-D, and KGF expression. IL-6, TNF-α, ST2, and FGF-2 expression levels were lower in patients taking amlodipine, with and without gingival enlargement. TGF-β1 and CTGF expression levels were highest in patients with amlodipine-induced gingival enlargement. SOD activity was also highest in these patients, whereas MDA levels were higher in patients with gingival enlargement without amlodipine. Our study highlights the impact of amlodipine-induced gingival enlargement on oral health and quality of life, emphasizing fibrosis and oxidative stress, and suggests the need for integrated healthcare approaches and further research.

Single-cell sequencing, spatial transcriptome ad periodontitis: Rethink pathogenesis and classification

OBJECTIVE

This narrative review illuminates on the application of single-cell RNA sequencing (scRNA-seq) and spatial transcriptomics (ST) in periodontitis and highlights the probability of relating cell population and gene signatures to the pathogenesis of the disease for a better diagnosis.

METHODS

An electronic search of the literature in the PubMed database for the keywords, "single cell sequencing" OR "spatial transcriptomics" and "periodontitis" OR "gingiva" OR "oral mucosa" yielded 486 research articles and reviews. After filtering duplicates and careful curation, 22 papers conducted in humans were retained.

RESULTS

The molecular mechanisms underlying periodontitis are complex and involve the interaction of multiple cells and various gene expressions. Most residing cells in periodontal tissues participate in maintaining homeostasis and health, while in addition to infiltrating immune cells contribute to the fight against the bacterial insult.

CONCLUSION

scRNA-seq and ST have provided new insights into the cellular and molecular changes associated with periodontitis for a better diagnosis and clinical outcome. New functions of cells and genes are revealed with these techniques; however, no cells or gene signatures are attributed to periodontitis so far.

Nesfatin-1 attenuated lipopolysaccharide-induced inflammatory response and senescence in human dental pulp cells

Lipopolysaccharide (LPS)-triggered damage in human dental pulp cells (hDPCs) is associated with the progression of gingivitis, which is inflammation of the gingival tissue. Nesfatin-1 is a peptide secreted by neurons and peripheral tissues. Here, we report a novel property of Nesfatin-1 in ameliorating LPS-induced inflammatory response and senescence in hDPCs. First, we demonstrate that Nesfatin-1 repressed LPS-triggered expression of inflammatory factors. Secondly, Nesfatin-1 restored telomerase activity and the expression of human telomerase reverse transcriptase (hTERT) and telomeric repeat binding factor 2 (TERF2) against LPS. Senescence-associated β-galactosidase (SA-β-gal) staining assay revealed that Nesfatin-1 attenuated LPS-induced cellular senescence in hDPCs. We also found that Nesfatin-1 increased telomerase activity in LPS-challenged hDPCs. It is also shown that Nesfatin-1 reduced the expression of plasminogen activator inhibitor-1 (PAI-1) and p16. Additionally, LPS stimulation reduced the expression of SIRT1, which was rescued by Nesfatin-1. However, the silencing of sirtuin1 (SIRT1) abrogated the protective property of Nesfatin-1 in preventing cellular senescence, implying that the function of Nesfatin-1 is regulated by SIRT1. Taken together, our findings suggest that Nesfatin-1 might possess a protective effect against gingivitis.

The IL-33/ST2 axis is protective against acute inflammation during the course of periodontitis

Periodontitis, which is induced by repeated bacterial invasion and the ensuing immune reactions that follow, is the leading cause of tooth loss. Periodontal tissue is comprised of four different components, each with potential role in pathogenesis, however, most studies on immune responses focus on gingival tissue. Here, we present a modified ligature-induced periodontitis model in male mice to analyze the pathogenesis, which captures the complexity of periodontal tissue. We find that the inflammatory response in the peri-root tissues and the expression of IL-6 and RANKL by Thy-1.2- fibroblasts/stromal cells are prominent throughout the bone destruction phase, and present already at an early stage. The initiation phase is characterized by high levels of ST2 (encoded by Il1rl1) expression in the peri-root tissue, suggesting that the IL-33/ST2 axis is involved in the pathogenesis. Both Il1rl1- and Il33-deficient mice exhibit exacerbated bone loss in the acute phase of periodontitis, along with macrophage polarization towards a classically activated phenotype and increased neutrophil infiltration, indicating a protective role of the IL-33/ST2 axis in acute inflammation. Thus, our findings highlight the hidden role of the peri-root tissue and simultaneously advance our understanding of the etiology of periodontitis via implicating the IL-33/ST2 axis.

Biological effects of IL-33/ST2 axis on oral diseases: autoimmune diseases and periodontal diseases

IL-33 is a relatively new member of the IL-1 cytokine family, which plays a unique role in autoimmune diseases, particularly some oral diseases dominated by immune factors. The IL-33/ST2 axis is the main pathway by which IL-33 signals affect downstream cells to produce an inflammatory response or tissue repair. As a newly discovered pro-inflammatory cytokine, IL-33 can participate in the pathogenesis of autoimmune oral diseases such as Sjogren's syndrome and Behcet's disease. Moreover, the IL-33/ST2 axis also recruits and activates mast cells in periodontitis, producing inflammatory chemokines and mediating gingival inflammation and alveolar bone destruction. Interestingly, the high expression of IL-33 in the alveolar bone, which exhibits anti-osteoclast effects under appropriate mechanical loading, also confirms its dual role of destruction and repair in an immune-mediated periodontal environment. This study reviewed the biological effects of IL-33 in autoimmune oral diseases, periodontitis and periodontal bone metabolism, and elaborated its potential role and impact as a disease enhancer or a repair factor.

Microbiota and IL-33/31 Axis Linkage: Implications and Therapeutic Perspectives in Atopic Dermatitis and Psoriasis

Microbiome dysbiosis and cytokine alternations are key features of atopic dermatitis (AD) and psoriasis (PsO), two of the most prevalent and burdensome pruritic skin conditions worldwide. Interleukin (IL)-33 and IL-31 have been recognized to be major players who act synergistically in the pathogenesis and maintenance of different chronic inflammatory conditions and pruritic skin disorders, including AD and PsO, and their potential role as therapeutic targets is being thoroughly investigated. The bidirectional interplay between dysbiosis and immunological changes has been extensively studied, but there is still debate regarding which of these two factors is the actual causative culprit behind the aetiopathological process that ultimately leads to AD and PsO. We conducted a literature review on the Pubmed database assessing articles of immunology, dermatology, microbiology and allergology with the aim to strengthen the hypothesis that dysbiosis is at the origin of the IL-33/IL-31 dysregulation that contributes to the pathogenesis of AD and PsO. Finally, we discussed the therapeutic options currently in development for the treatment of these skin conditions targeting IL-31, IL-33 and/or the microbiome.