The Antimicrobial Peptide LL-37 as a Predictor Biomarker for Periodontitis with the Presence and Absence of Smoking: A Case-Control Study

Host Markers of Periodontal Diseases: Meta-Analysis of Diagnostic Accuracy Studies

OBJECTIVE

To identify host markers with optimal diagnostic performance for clinical implementation in the diagnosis of periodontal diseases and prediction of future disease progression and/or disease resolution.

MATERIAL AND METHODS

Cross-sectional and prospective studies with ≥ 20 participants per group, reporting diagnostic accuracy (e.g., area under the curve [AUC]) of host markers for periodontal diagnosis (focused question 1 [FQ1]), periodontitis progression/relapse (FQ2) or resolution (FQ3) were searched in three electronic databases. Meta-analyses estimating diagnostic accuracy (DA) for individual host markers and for grouped salivary and gingival crevicular fluid (GCF) markers independently were performed whenever two or more studies were identified.

RESULTS

Sixty-one eligible studies were identified, of which 13 were included in meta-analyses for FQ1 (discrimination between health and periodontitis). Matrix metalloproteinase-8 (MMP-8) was the most reported biomarker in both saliva and GCF, with comparable AUC (0.70-0.90), sensitivity (0.49-0.84) and specificity (0.62-0.79) in both sample types. Cytokines had good ability for discrimination of periodontitis/gingivitis versus health, although they were substantially less accurate for periodontitis versus gingivitis. Combinations of cytokines and MMPs tended to increase overall diagnostic accuracy but without significant improvement in the case of periodontitis/gingivitis discrimination. Bone markers were the best performing group of salivary markers (AUC = 0.91) when compared to cytokines (AUC = 0.86) and MMPs (AUC = 0.77). GCF microRNAs (MiRs) were a singly meta-analysed group of biomarkers demonstrating AUC = 0.79.

CONCLUSION

Reported studies on host periodontal markers exhibit serious limitations regarding clinical and validation standards, being the main cause for lack of progress in clinical implementation of biomarkers in periodontal classification. Disease-specific markers such as bone markers showed better diagnostic performance (from limited number of studies) for the diagnosis of periodontitis when compared to cytokines and MMPs.

Cathelicidin LL-37 in periodontitis: current research advances and future prospects - A review

LL-37 is the sole member of the cathelicidin family of antimicrobial peptides in humans, primarily produced by phagocytic leukocytes and epithelial cells, mediating a wide range of biological responses. Discovered in human neutrophils, LL-37 is known for its broad-spectrum antimicrobial activity and immunomodulatory functions. In periodontitis, LL-37 is mainly expressed in gingival epithelium, gingival sulcus fluid, and saliva. Emerging evidence from several studies suggests that LL-37 is significant in the development of periodontitis, exhibiting antimicrobial, immunomodulatory, and tissue regenerative effects. Several studies have quantified the levels of LL-37 in gingival crevicular fluid (GCF), revealing elevated levels in patients with periodontitis compared to healthy controls. This review summarizes the expression and roles of LL-37 in periodontitis, providing new perspectives and insights into its pathogenesis and potential treatments. Additionally, this review aims to identify potential areas for future research, including therapeutic applications and biomarker development.

Vitamin D and LL-37 in Serum and Saliva: Insights into Oral Immunity

(1) Background: In recent years, there has been a growing interest in understanding the innate immunity of the mouth, particularly the mechanisms through which vitamin D influences oral health. Researchers have increasingly focused on the association between vitamin D and the antimicrobial peptide LL-37 since the CAMP gene, responsible for encoding the LL-37 peptide, is a direct target of both vitamin D and its receptor (vitamin D receptor, VDR). This study aimed to explore the correlation between the 25-hydroxyvitamin D (25(OH)D) levels and the concentration of the LL-37 peptide in both serum and saliva. The objective was to compare the serum concentrations of 25(OH)D and ll-37 with those in saliva and to access the correlations between the two compounds. (2) Methods: Serum and whole saliva samples were collected from 72 healthy adults (mean age 28.68 ± 8.35). The levels of 25(OH)D and LL-37 were assessed in both the saliva and serum samples using commercially available enzyme-linked immunosorbent assay (ELISA) kits. (3) Results: The 25(OH)D levels in the serum (median 5.92 ng/mL, min-max 2.7-10.4 ng/mL) correlated with the LL-37 serum levels (62 ng/mL, min-max 18-378 ng/mL; Pearson's r 0.328, p = 0.005). Additionally, the 25(OH)D levels in saliva (median 1.16 ng/mL, min-max 0.54-2.12 ng/mL) strongly correlated with the LL-37 salivary levels (median 44 ng/mL, min-max 6.5-205 ng/mL; Pearson's r 0.667, p < 0.001). The 25(OH)D salivary levels demonstrated a robust correlation with the LL-37 salivary levels. (4) Conclusions: This discovery emphasizes the complex interplay between vitamin D and LL-37 and lay the groundwork for the further exploration of vitamin D's role in oral immune function.

The Variability of the Salivary Antimicrobial Peptide Profile: Impact of Lifestyle

Saliva is crucial in maintaining oral health; its composition reflects the body's physiological and diseased state. Among salivary components, antimicrobial peptides (AMPs) stand out for their broad antimicrobial activities and role in modulating the oral microbiota and innate immune response. Local and systemic diseases can affect the levels of AMPs in saliva, making them attractive biomarkers. However, the large variability in their concentrations hampers their use in diagnostics. Knowledge of the various factors influencing the profile of salivary AMPs is essential for their use as biomarkers. Here, we examine how lifestyle factors such as physical activity, dietary supplementation, tobacco smoking, and psychological stress impact salivary AMP levels. By understanding these sources of variability, we can take a step forward in using AMPs for diagnostics and prognostics and develop new tailored and preventative approaches.

Potential Association of Maker Expression of Low-Density Neutrophils and Their Phenotypes in Patients with Periodontitis: Control Study

Background

Neutrophils play an important role in maintaining periodontal status in conditions of healthy homeostasis. They achieve their surveillance function by continuously migrating to the gingival sulcus and eradicating periodontal pathogens. In addition, neutrophils are considered an integral element in the pathogenesis of periodontal diseases. Among several neutrophil subsets, low-density neutrophils (LDN) have recently received attention and are linked with cancer, immunological, inflammatory, and infectious diseases. However, the presence, phenotypes, and potential role of LDN in the pathogenesis of periodontitis have not yet been investigated.

Objectives

To investigate the presence, subsets (normal, band, suppressive, and active), and phenotypes via marker expression surface protein known as the cluster of differentiation (CD) (CD16b, CD14, CD15, and CD62L) of LDN in patients with periodontitis.

Materials and Methods

The observational case-control study was conducted to estimate the potential role of LDNs in periodontitis. Venous blood and periodontal indices were obtained from 40 healthy control individuals and 60 periodontitis patients. Subsequently, CD16b, CD62L, CD14, and CD15 expression on the surface of LDN was examined by multicolor flow cytometry, and their subsets were classified as "normal" (CD16brightCD62Lbright), "bands" (CD16dimCD62Lbright), "suppressive" (CD16brightCD62Ldim), and "active" (CD16brightCD62Lnegative).

Results

There was a significant difference in the expression of LDN markers for active and suppressive phenotypes, respectively, favoring periodontitis over the control group. In contrast, there were significantly higher levels of CD16b, CD62L, and CD15 ("normal") in the control group when compared with the periodontitis group.

Conclusion

LDN was associated with periodontitis as it was significantly increased in the periodontitis group in comparison with the control group and was positively correlated with all periodontal parameters. Cells from both groups of patients (periodontitis and control) expressed a normal mature phenotype (CD16b + High, CD62L + High, CD15+, and CD14-). Regarding subsets, the normal LDN (CD16brightCD62Lbright) was the most predominant phenotype in both periodontitis and control groups. However, the active subset increased in periodontitis compared to normal, indicating their destructive role in periodontitis.

Effect of Occupational Stress on Periodontitis According to the Salivary RANKL Level Among Iraqi Employees

Background

Findings show that periodontitis does not affect all populations; similarly, some individuals present risk conditions such as occupational stress, making them more susceptible to developing periodontitis through unhealthy habits like poor oral hygiene and immune suppression. Periodontitis triggers an inflammatory host immune response; "Receptor Activator Nuclear Factor KB ligand (RANKL)" is the primary regulator of osteoclast differentiation and activity. It was found that osteoclastic bone damage caused by periodontitis depends on the RANKL produced by osteoblastic and periodontal ligament cells.

Objective

This study aimed to assess the effect of occupational stress on employees with periodontitis using salivary RANKL marker.

Material and Methods

A case-control analysis was done at my clinic with 90 male employees aged 30-50. The participants completed self-administered questionnaires and had periodontal exams. Employee occupational stress was estimated using a life events scale questionnaire. Calibrated dentists performed the parameters used in the periodontal assessment after collecting whole unstimulated salivary samples from each employee to measure salivary RANKL using ELISA technique.

Results

The present finding revealed a statistically significant difference among groups in "probing pocket depth, plaque index, bleeding on probing, clinical attachment level, and salivary RANKL level". They were higher in the stressed employees' group, which is not statistically significant.

Conclusion

The findings of this investigation observed that occupational stress increased clinical periodontal parameters and salivary RANKL of periodontitis in employees.