The modulation of the TREM-1/PGLYRP1/MMP-8 axis in peri-implant diseases

Realizing the clinical utility of saliva for monitoring oral diseases

In the era of personalized/precision health care, additional effort is being expended to understand the biology and molecular mechanisms of disease processes. How these mechanisms are affected by individual genetics, environmental exposures, and behavioral choices will encompass an expanding role in the future of optimally preventing and treating diseases. Considering saliva as an important biological fluid for analysis to inform oral disease detection/description continues to expand. This review provides an overview of saliva as a diagnostic fluid and the features of various biomarkers that have been reported. We emphasize the use of salivary biomarkers in periodontitis and transport the reader through extant literature, gaps in knowledge, and a structured approach toward validating and determine the utility of biomarkers in periodontitis. A summation of the findings support the likelihood that a panel of biomarkers including both host molecules and specific microorganisms will be required to most effectively identify risk for early transition to disease, ongoing disease activity, progression, and likelihood of response to standard periodontal therapy. The goals would be to develop predictive algorithms that serve as adjunctive diagnostic tools which provide the clinician and patient important information for making informed clinical decisions.

Oral Fluid Biomarkers for Peri-Implantitis: A Scoping Review

Peri-implantitis, a prevalent complication in dental implant therapy, poses a significant threat to long-term implant success. The identification of reliable biomarkers for the early detection and monitoring of peri-implantitis is crucial for timely intervention and improved treatment outcomes. Salivary and peri-implant sulcular fluid (PISF) biomarkers have become promising diagnostic tools in the field of implant dentistry. This scoping review aims to explore current studies in the literature on salivary and PISF biomarkers for peri-implantitis. A systematic search was conducted on 2 databases (PubMed and Scopus) to identify relevant studies published up to January 2023. A total of 86 articles were included, which underwent data extraction and analysis. Several biomarkers have been investigated in salivary and PISF samples for association with peri-implantitis. Investigations included a wide range of biomarkers, including inflammatory markers, matrix metalloproteinases and bone loss markers. The findings suggested that certain salivary and PISF biomarkers demonstrated potential in distinguishing healthy peri-implant conditions from peri-implantitis. Elevated levels of proinflammatory cytokines, such as interleukin-1β (IL-1β) and interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α), and matrix metalloproteinases, have been consistently associated with peri-implantitis. Additionally, alterations in bone loss markers have shown potential as indicators of disease progression and treatment response. In conclusion, this scoping review provides an overview of current knowledge on salivary and PISF biomarkers for peri-implantitis. The identified biomarkers are promising as noninvasive diagnostic tools for early detection, monitoring, and personalised management of peri-implantitis. Future studies should focus on establishing standardised protocols and conducting well-designed clinical trials to validate the diagnostic accuracy and clinical relevance of these biomarkers.

Peri-Implant Surgical Treatment Downregulates the Expression of sTREM-1 and MMP-8 in Patients with Peri-Implantitis: A Prospective Study

sTREM-1 and its ligand PGLYRP1 play an essential role in the inflammatory process around teeth and implants. In this study, we aimed to evaluate the impact of peri-implant treatment on the salivary levels of the sTREM-1/PGLYRP-1/MMP-8 axis after 3 months. A total of 42 participants (with a mean age of 61 years old ± 7.3) were enrolled in this longitudinal study, 24 having peri-implant mucositis (MU) and 18 having peri-implantitis (PI). Clinical peri-implant parameters, such as probing pocket depth (PPD), % of plaque, and bleeding on probing (BOP), and the whole unstimulated saliva samples were evaluated at baseline and 3 months after treatment. The MU group received nonsurgical peri-implant treatment, while the PI group received open-flap procedures. The levels of sTREM-1, PGLYRP-1, MMP-8, and TIMP-1 were analyzed using enzyme-linked immunosorbent assays. BOP, plaque levels, and PPD significantly reduced after treatment in both groups. A significant decrease in the salivary levels of sTREM-1, MMP-8, and TIMP-1 in the PI group and PGLYRP1 and TIMP-1 in the MU group were observed. Salivary levels of sTREM-1 were significantly reduced in patients with PI but not with MU. Additionally, peri-implant treatment had a significantly higher impact on MMP-8 reduction in patients with PI than in those with MU.

Evaluation of "soluble triggering receptor expressed on myeloid cells-1 (sTREM-1), interleukin-1β, and matrix metalloproteinase-8" as a short panel of salivary biomarkers in patients with and without stage III/IV periodontitis and type 2 diabetes mellitus

Background and aim

Periodontitis involves a dynamic disease process, demanding the identification of biomarkers to diagnose the current state of disease activity. Therefore this study assessed the potential of "sTREM-1, IL-1β, and MMP-8" as a short panel of biomarkers of host biological process indicating the inflammatory burden in periodontium and thereby serving as a panel of diagnostic markers in periodontal disease.

Methods

Sixty eight patients were recruited and allotted into four groups comprising of subjects with clinically healthy gingiva and Stage III/IV Periodontitis with and without type 2 diabetes with HbA1c levels in the range of 6.5-7.9%. Periodontal parameters were measured and full mouth radiographic assessment was done. Whole saliva (unstimulated) samples were collected from all patients and estimation of the levels of markers was done employing ELISA.

Results

All the three biomarkers were noted to be the lowest in group I (sTREM-1: 75.63 ± 13.77; IL-1β: 15.67 ± 3.39; MMP-8: 85.83 ± 22.32) and highest in group IV (sTREM-1: 138.83 ± 14.89; IL-1β: 39.19 ± 7.20; MMP-8: 201.15 ± 50.32) with statistically significant difference. The difference observed between groups II and III for all the biomarkers assessed were statistically insignificant. The clinical parameters and HbA1c levels had positive correlation with the levels of biomarkers which was statistically significant.

Conclusion

This study unveils the potential of the short panel of biomarkers ("sTREM-1, IL-1β, and MMP-8") to be used as diagnostic and possible prognostic markers for Periodontitis. It further corroborates the role of type 2 diabetes mellitus in amplifying the diverse processes that result in periodontal destruction.

Saliva as a Source of Biomarkers for Periodontitis and Periimplantitis

Saliva has the potential to be used as a diagnostic and monitoring tool for various diseases if biomarkers of an adequate sensitivity and specificity could be identified. Several reviews and even meta-analyses have been performed in recent years, which have found some candidate biomarkers for periodontitis, like macrophage inflammatory protein-1 alpha, interleukin-1ß, interleukin-6, matrix metalloproteinase-8, or hemoglobin. However, none of those are currently in use to replace conventional periodontal diagnostics with a periodontal probe. For periimplantitis, to date, heterogeneity of different study protocols and implant types did not permit to discover clear biomarkers, which were able to distinguish between healthy and diseased implants. Few proinflammatory cytokines, similar to periodontitis, have been characterized as adjunct tools to clinical diagnosis. The additional determination of antimicrobial peptides, bone turnover markers, and bacteria could help to enhance sensitivity and specificity in a combined model for periodontitis and periimplantitis. Furthermore, proteomic approaches might be preferred over single biomarker determinations. A global consensus is also needed to harmonize salivary sampling methods as well as procedures of biomarker analysis to ensure future comparability.

Removal of nonimpacted third molars alters the periodontal condition of their neighbors clinically, immunologically, and microbiologically

Considering the adverse effects of nonimpacted third molars (N-M3s) on the periodontal health of adjacent second molars (M2s), the removal of N-M3s may be beneficial to the periodontal health of their neighbors. This study aimed to investigate the clinical, immunological, and microbiological changes of the periodontal condition around M2s following removal of neighboring N-M3s across a 6-month period. Subjects with at least one quadrant containing an intact first molar (M1), M2, and N-M3 were screened and those who met the inclusion criteria and decided to receive N-M3 extraction were recruited in the following investigation. M2 periodontal condition was interrogated before M3 extraction (baseline) and at 3 and 6 months postoperatively. Improvements in clinical periodontal indexes of M2s in response to their adjacent N-M3 removal, along with changes in inflammatory biomarkers among gingival crevicular fluid (GCF) and the composition of subgingival plaque collected from the distal sites of the M2s of the targeted quadrant were parallelly analyzed. Complete data of 26 tooth extraction patients across the follow-up period were successfully obtained and subsequently applied for statistical analysis. Compared to the baseline, the periodontal condition of M2s was significantly changed 6 months after N-M3 removal; specifically, the probing depth of M2s significantly reduced (P < 0.001), the matrix metalloproteinase (MMP)-8 concentration involved in GCF significantly decreased (P = 0.025), and the abundance of the pathogenic genera unidentified Prevotellaceae and Streptococcus significantly decreased (P < 0.001 and P = 0.009, respectively). We concluded that N-M3 removal was associated with superior clinical indexes, decreased GCF inflammatory biomarkers, and reduced pathogenic microbiome distribution within the subgingival plaque. Although the retention or removal of N-M3s continues to be controversial, our findings provide additional evidence that medical decisions should be made as early as possible or at least before the neighboring teeth are irretrievably damaged.

Levels of Gene Expression of Immunological Biomarkers in Peri-Implant and Periodontal Tissues

This study compared the gene expression of the immunoinflammatory markers interleukin (IL)-6, IL-1ß, and tumor necrosis factor alpha (TNF-α), the matrix metalloproteinases (MMP)-1, -2, -8, and -9, and the tissue inhibitors of matrix metalloproteases (TIMP)-1 and -2 in the gingival tissue of individuals with periodontal and peri-implant disease. The study population included individuals with four periodontal statuses: periodontal health (PH group, n = 20); periodontitis (P group, n = 20); peri-implant health (PIH group, n = 20), and peri-implantitis (PI group, n = 20). Gingival biopsies were collected from one tooth per patient according to the inclusion criteria of each group. The mRNA levels of IL-6, IL-1ß, TNF-α, MMP-1, MMP-2, MMP-8, MMP-9, TIMP-1, and TIMP-2 were evaluated by qPCR. The levels of IL-1ß were significantly higher in the PI group when compared to the other groups (p < 0.05), while the levels of IL-6 were significantly higher in the groups with periodontal and peri-implant disease when compared with the healthy groups (p < 0.05); however, the levels of IL-6 did not differ between the PI and P groups (p > 0.05). For all other studied biomarkers, no significant differences were observed between groups (p > 0.05). IL-6 and IL-1ß presented higher levels of mRNA in diseased periodontal and peri-implant tissues. However, the expression of metalloproteinases and their inhibitors did not differ between the different periodontal statuses.

Evaluation of adipokines and inflammatory mediator expression levels in patients with periodontitis and peri-implantitis: a cross-sectional study

OBJECTIVES

The aim of this study was to analyze the mRNA and protein expression of adiponectin, leptin, visfatin, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 levels in periodontitis and peri-implantitis sites in systemically healthy individuals and to investigate the influence of the presence of current periodontitis on their expression levels in peri-implantitis sites.

MATERIALS AND METHODS

Soft tissue biopsy samples were collected from 60 systemically healthy patients [15 periodontally healthy patients (group I), 16 patients with periodontitis (group II), 15 patients with peri-implantitis (group III), and 14 patients with peri-implantitis and periodontitis (group IV)]; mRNA expression levels of adiponectin, leptin, visfatin, TNF-α, and IL-6 were measured by quantitative real-time PCR; and their protein levels were assessed by immunohistochemistry.

RESULTS

The mRNA expression levels of all biomarkers were significantly higher for group II compared to group I, while significantly higher levels of leptin, TNF-α, and IL-6 were observed in group III in comparison with group I. Group II exhibited significantly higher mRNA expression of adiponectin and TNF-α than group III. Group IV showed significantly higher expression levels of adiponectin, leptin, TNF-α, and IL-6 compared to group III. Regarding the expression of protein levels, which was estimated through quantification of the histoscore, both groups II and III presented higher H-scores than group I for all biomarkers except leptin.

CONCLUSIONS

The presence of current periodontitis may enhance expression levels of adiponectin, leptin, TNF-α, and IL-6 in peri-implant soft tissue.

CLINICAL RELEVANCE

The presence of periodontitis is an important risk factor for the severity of peri-implant inflammation as well as the onset of peri-implantitis.