Salivary and gingival crevicular fluid histatin in periodontal health and disease

Let-7e as Potential Diagnostic Biomarkers in Early Detection of Peri-Implant Diseases: A Cross-Sectional Study

OBJECTIVES

Peri-implant diseases (PID), specifically peri-implant mucositis and peri-implantitis, significantly jeopardize dental implant success. Traditional diagnostic methods, relying on periodontal probing and radiographs, have limitations in precisely diagnosing these conditions. Recent studies suggest that microRNA (miRNA) profiling might be a breakthrough in the early detection of PID. This study aimed to evaluate the expression levels of specific miRNAs-miR-98, miR-145, miR-146a, and let-7e-in individuals with peri-implant mucositis and peri-implantitis compared to a healthy control.

METHODS

From January 2022 to October 2023, 19 participants with 38 dental implants were recruited according to established criteria. After clinical and radiographic evaluations, dental implants were grouped as peri-implant health (Group 1), peri-implant mucositis (Group 2), and peri-implantitis (Group 3). Subsequently, peri-implant crevicular fluid (PICF) samples were collected and analyzed through real-time quantitative polymerase chain reaction (qPCR).

RESULTS

Based on the findings, only let-7e biomarkers were consistently detected across all samples, with their expression increased eightfold in peri-implant mucositis and 94-fold in peri-implantitis cases. Kruskal-Wallis's test showed a statistically significant difference in relative gene expression of let-7e between the different groups, H(2) = 25.825, p ≤ 0.001.

CONCLUSIONS

Our study indicates that miRNA biomarkers, particularly let-7e, may play a significant role in the development and progression of PID, highlighting the need for further in-depth investigation, with PICF offering a practical, noninvasive sampling method.

Salivary Antimicrobial Peptide Histatin-5 Does Not Display Zn(II)-Dependent or -Independent Activity against Streptococci

Histatin-5 (Hst5) is a member of the histatin superfamily of cationic, His-rich, Zn(II)-binding peptides in human saliva. Hst5 displays antimicrobial activity against fungal and bacterial pathogens, often in a Zn(II)-dependent manner. In contrast, here we showed that under in vitro conditions that are characteristic of human saliva, Hst5 does not kill seven streptococcal species that normally colonize the human oral cavity and oropharynx. We further showed that Zn(II) does not influence this outcome. We then hypothesized that Hst5 exerts more subtle effects on streptococci by modulating Zn(II) availability. We initially proposed that Hst5 contributes to nutritional immunity by limiting nutrient Zn(II) availability and promoting bacterial Zn(II) starvation. By examining the interactions between Hst5 and Streptococcus pyogenes as a model Streptococcus species, we showed that Hst5 does not influence the expression of Zn(II) uptake genes. In addition, Hst5 did not suppress growth of a ΔadcAI mutant strain that is impaired in Zn(II) uptake. These observations establish that Hst5 does not promote Zn(II) starvation. Biochemical examination of purified peptides further confirmed that Hst5 binds Zn(II) with high micromolar affinities and does not compete with the AdcAI high-affinity Zn(II) uptake protein for binding nutrient Zn(II). Instead, we showed that Hst5 weakly limits the availability of excess Zn(II) and suppresses Zn(II) toxicity to a ΔczcD mutant strain that is impaired in Zn(II) efflux. Altogether, our findings led us to reconsider the function of Hst5 as a salivary antimicrobial agent and the role of Zn(II) in Hst5 function.

The assessment of sIgA, histatin-5, and lactoperoxidase levels in saliva of adolescents with dental caries

BACKGROUND

Saliva contains a number of protective factors such as mucins, immunoglobulins (e.g., IgA, IgG, and IgM), and enzymes (e.g., lysozyme and lactoperoxidases) that play an important role in the maintenance of oral health. The aim of this study was to compare levels of sIgA, histatin-5, and lactoperoxidase in saliva of adolescents with dental caries.

MATERIAL AND METHODS

Thirty-five adolescents (age 18 years) from high school were examined. Eight subjects with DMF=3 (Group I) and 27 adolescents with DMF>11 (Group II) were enrolled for this study. Clinical evaluation procedures comprised oral examination (including tooth, periodontal, and oral mucosal status) and collection of saliva samples. Saliva was collected for enzyme-linked immunosorbent assay (ELISA) and was used for determination of sIgA, histatin-5, and lactoperoxidase levels.

RESULTS

Our results showed that adolescents with very high intensity of dental caries (DMF>11) had increased levels of sIgA, histatin-5, and lactoperoxidase compared to adolescents with lower intensity of caries. The increase was statistically significant (p<0.05).

CONCLUSIONS

We suggest that high intensity of caries is associated with increased levels of some salivary components - sIgA, histatin-5 and lactoperoxidase - that possess strong bactericidal or bacteriostatic effects, resulting in aggregation of oral bacteria and their clearance from the oral cavity.