Porphyromonas gingivalis interaction with Candida albicans allows for aerobic escape, virulence and adherence

In the oral cavity Candida albicans interacts with many oral bacteria, including Porphyromonas gingivalis, both physically and metabolically. The aim of this in vitro study was to characterize these interactions and study their effects on the survival of P. gingivalis. First, metabolic interactions were evaluated by counting the colony forming units (CFU) after co-culturing. The results indicated that the anaerobic bacterium P. gingivalis survives under aerobic conditions when co-cultured with C. albicans. This is due to the oxygen consumption by C. albicans as determined by a reduction in survival upon the addition of Antimycin A. By measuring the protease activity, it was found that the presence of C. albicans induced gingipain activity by P. gingivalis, which is an important virulence factor. Adherence of P. gingivalis to hyphae of C. albicans was observed with a dynamic flow system. Using various C. albicans mutants, it was shown that the mechanism of adhesion was mediated by the cell wall adhesins, members of the agglutinin-like sequence (Als) family: Als3 and Als1. Furthermore, the two microorganisms could be co-cultured into forming a biofilm in which P. gingivalis can survive under aerobic culturing conditions, which was imaged using scanning electron microscopy. This study has further elucidated mechanisms of interaction, virulence acquisition and survival of P. gingivalis when co-cultured with C. albicans. Such survival could be essential for the pathogenicity of P. gingivalis in the oxygen-rich niches of the oral cavity. This study has emphasized the importance of interaction between different microbes in promoting survival, virulence and attachment of pathogens, which could be essential in facilitating penetration into the environment of the host.

Fecal proteolytic profiling of pediatric inflammatory bowel disease: A pilot study

Colonoscopy is the gold standard for diagnosing inflammatory bowel disease (IBD). However, this invasive procedure has a high burden for pediatric patients. Previous research has shown elevated fecal amino acid concentrations in children with IBD versus controls. We hypothesized that this finding could result from increased proteolytic activity. Therefore, the aim of this study was to investigate whether fecal protease-based profiling was able to discriminate between IBD and controls. Protease activity was measured in fecal samples from patients with IBD (Crohn's disease (CD) n = 19; ulcerative colitis (UC) n = 19) and non-IBD controls (n = 19) using a fluorescence resonance energy transfer (FRET)-peptide library. Receiver operating characteristic (ROC) curve analysis was used to determine the diagnostic value of each FRET-peptide substrate. Screening the FRET-peptide library revealed an increased total proteolytic activity (TPA), as well as degradation of specific FRET-peptides specifically in fecal samples from IBD patients. Based on level of significance (p < .001) and ROC curve analysis (AUC > 0.85), the fluorogenic substrates W-W, A-A, a-a, F-h, and H-y showed diagnostic potential for CD. The substrates W-W, a-a, T-t, G-v, and H-y showed diagnostic potential for UC based on significance (p < .001) and ROC analysis (AUC > 0.90). None of the FRET-peptide substrates used was able to differentiate between protease activity in fecal samples from CD versus UC. This study showed an increased fecal proteolytic activity in children with newly diagnosed, treatment-naïve, IBD. This could lead to the development of novel, noninvasive biomarkers for screening and diagnostic purposes.

Carbon dots combined with phytosphingosine inhibit acid-induced demineralization of hydroxyapatite in vitro

OBJECTIVES

To study the effects of carbon dots (CDs), in combination with phytosphingosine (PHS), against acid-induced demineralization of hydroxyapatite in vitro.

METHODS

CDs were generated from citric acid and urea by microwave heating. Transmission electron microscope (TEM), FT-IR, and fluorescence intensity were used to characterize the CDs. A hydroxyapatite (HAp) model was used to investigate the protective effects of CDs, PHS, and their combinations with and without a salivary pellicle against acid-induced demineralization in vitro. Ca2+ release as a parameter to evaluate the inhibition of demineralization was measured by capillary electrophoresis. The interactions between CDs, PHS, and HAp discs were investigated using a fluorescence detector.

RESULTS

Uniform-sized CDs were synthesized, showing typical optical characteristics. CDs exhibited no inhibition of acid-induced demineralization in vitro, in contrast to PHS. Notably, a pre-coating of CDs increased the protective effects of PHS against acid-induced demineralization, which was not disturbed by the presence of a salivary pellicle and Tween 20. Scanning electron microscope (SEM) confirmed the binding and layers formed of both CDs and PHS to the HAp surfaces. Based on fluorescence spectra CDs binding to HAp seemed to be dependent on Ca2+ and PO43- interactions.

CONCLUSIONS

CDs combined with PHS showed protective effects against acid-induced demineralization of HAp discs in vitro.

[Phytosphingosine, a new ingredient for oral care products?]

Despite the availability of a wide range of (fluoridated) oral care products, there is a constant search under way for new substances that contribute to a healthy mouth. Laboratory research shows that the lipid phytosphingosine forms a molecular layer on hydroxyapatite and protects it against acid-induced demineralization and bacterial adhesion. In the future, phytosphingosine may be used in the future as a new ingredient in oral care products for the prevention of tooth erosion and biofilm-related disorders, such as caries, gingivitis and periodontitis.

Exploring the Correlation between Salivary Spinnbarkeit and Caries Scores

INTRODUCTION

In this study, the relationship between the spinnbarkeit, i.e., the stretchability of saliva, and dental caries was investigated.

METHODS

Dentistry students were divided into a group with more than 2 decayed, missed, and filled teeth (DMFT ≥2, n = 30) and caries-free group (DMFT = 0, n = 36).

RESULTS

Unstimulated saliva flow rate, pH, and spinnbarkeit were determined. Salivary spinnbarkeit was significantly lower in the caries-prone group compared to the caries-free group (5.4 ± 3.9 mm vs. 13.5 ± 7.6 mm, respectively, p < 0.001).

CONCLUSION

This suggests that saliva with high spinnbarkeit protects better against dental caries.

Development of New Models of Oral Mucosa to Investigate the Impact of the Structure of Transmembrane Mucin-1 on the Mucosal Pellicle Formation and Its Physicochemical Properties

The mucosal pellicle (MP) is a biological film protecting the oral mucosa. It is composed of bounded salivary proteins and transmembrane mucin MUC1 expressed by oral epithelial cells. Previous research indicates that MUC1 expression enhances the binding of the main salivary protein forming the MP, MUC5B. This study investigated the influence of MUC1 structure on MP formation. A TR146 cell line, which does not express MUC1 natively, was stably transfected with genes coding for three MUC1 isoforms differing in the structure of the two main extracellular domains: the VNTR domain, exhibiting a variable number of tandem repeats, and the SEA domain, maintaining the two bound subunits of MUC1. Semi-quantification of MUC1 using dot blot chemiluminescence showed comparable expression levels in all transfected cell lines. Semi-quantification of MUC5B by immunostaining after incubation with saliva revealed that MUC1 expression significantly increased MUC5B adsorption. Neither the VNTR domain nor the SEA domain was influenced MUC5B anchoring, suggesting the key role of the MUC1 N-terminal domain. AFM-IR nanospectroscopy revealed discernible shifts indicative of changes in the chemical properties at the cell surface due to the expression of the MUC1 isoform. Furthermore, the observed chemical shifts suggest the involvement of hydrophobic effects in the interaction between MUC1 and salivary proteins.

Saliva Collection Methods Among Children and Adolescents: A Scoping Review

OBJECTIVE

Saliva can be used for screening and diagnostic purposes. Although multiple saliva collection methods are available, their use in children can be limited due to lack of cooperation, developmental stage, and age. The aim of this scoping review was to comprehensively appraise the different methods of saliva collection among both children and adolescents by assessing the available scientific literature.

METHODS

A literature search was performed using the databases PubMed, Embase, and Web of Science. Eligible studies on saliva collection methods among children and adolescents were included for this review.

RESULTS

The literature search identified 249 eligible articles, of which 205 had a cross-sectional study design. Four distinct saliva collection methods have surfaced: the drooling method, the absorption method, the spitting method, and the suction method. Among infants or children under the age of 6 years, the suction and absorption methods were most preferred. The drooling and spitting methods were only applicable among children above the age of 3 years. When children were not willing to cooperate, the absorption method was most feasible. In adolescents and older children, no specific method was found to be preferred over another method.

CONCLUSION

Overall, saliva collection is well tolerated by children and adolescents, with the absorption and suction methods being preferred with young and uncooperative children.

The impact of saliva collection methods on measured salivary biomarker levels

Saliva diagnostics have become increasingly popular due to their non-invasive nature and patient-friendly collection process. Various collection methods are available, yet these are not always well standardized for either quantitative or qualitative analysis. In line, the objective of this study was to evaluate if measured levels of various biomarkers in the saliva of healthy individuals were affected by three distinct saliva collection methods: 1) unstimulated saliva, 2) chew stimulated saliva, and 3) oral rinse. Saliva samples from 30 healthy individuals were obtained by the three collection methods. Then, the levels of various salivary biomarkers such as proteins and ions were determined. It was found that levels of various biomarkers obtained from unstimulated saliva were comparable to those in chew stimulated saliva. The levels of potassium, sodium, and amylase activity differed significantly among the three collection methods. Levels of all biomarkers measured using the oral rinse method significantly differed from those obtained from unstimulated and chew-stimulated saliva. In conclusion, both unstimulated and chew-stimulated saliva provided comparable levels for a diverse group of biomarkers. However, the results obtained from the oral rinse method significantly differed from those of unstimulated and chew-stimulated saliva, due to the diluted nature of the saliva extract.

The minimally important difference for the Xerostomia Inventory among Sjögren's disease patients

OBJECTIVE

Until now, the clinically relevant improvement for the Xerostomia Inventory (XI) has not been defined. Therefore, our aim was to determine the Minimally Important Difference (MID) of the XI for improvement in dry-mouth symptoms in SjD patients.

METHOD

The study recruited 34 SjD patients who underwent sialendoscopy of major salivary glands and 15 SjD patients in a nonintervention control group. XI scores were assessed at several time points. The MID was determined from the mean difference in XI scores between the groups with and without improvement.

RESULTS

In the control group, no significant XI score changes were seen. In the sialendoscopy group, a clinically relevant XI score change of four scale points was identified after 1 week. For a prolonged duration (≥16 weeks), a minimum reduction of seven scale points in the XI score was required to indicate clinically relevant improvement.

CONCLUSION

In SjD patients, a minimum change of four points in the XI score indicates a clinically relevant improvement for evaluating short-term effects. For prolonged effects, a clinically relevant improvement requires a MID of seven points. The determination of the MID in XI could assist in future studies that evaluate changes in xerostomia.

The diagnostic power of salivary electrolytes for Sjögren's disease: a systematic literature review and meta-analysis

OBJECTIVES

To perform a systematic review and meta-analysis to determine the power of salivary electrolytes for the diagnosis of Sjögren's disease (SjD).

METHODS

A literature search was conducted (last search March 2023) using PubMed and Web of Science and completed with a manual search. Articles were screened for reports of human salivary ion concentrations, comparing SjD patients with healthy controls and/or sicca patients. Articles not using the SjD classification criteria or performing the classification as part of the experimental design were excluded. Forest plots were used to present the meta-analyses results for each ion, distinguishing between salivary type (unstimulated and stimulated whole saliva, submandibular/sublingual and parotid saliva).

RESULTS

A total of 21 out of 722 articles were eligible for inclusion. For SjD patients a significant increase in salivary ion concentration was observed for sodium, chloride and calcium when comparing to healthy controls. Significant differences between SjD and sicca patients were noted for sodium, chloride, phosphate, calcium, phosphate, nitrite and nitrate. Stimulated whole saliva showed larger variability in results between studies in comparison to other types of saliva (unstimulated whole saliva, submandibular/sublingual saliva and parotid saliva).

CONCLUSIONS

Despite differences in saliva type, salivary ion levels could be utilised for the screening for SjD. Making use of chloride in combination with sodium would be most promising for distinguishing SjD patients from healthy controls and adding phosphate to potentially make a distinguishment with sicca patients. Unstimulated whole saliva should be the first choice when testing salivary ion concentrations.

Sialagogic Effects Through Olfactory Stimulation with Mastic Resin and α-pinene Volatiles in vivo

BACKGROUND

Xerostomia, often associated with decreased saliva quality, poses challenges due to limited treatment efficacy. This study aimed to investigate alternative approaches to enhance saliva secretion through olfactory volatile stimulation with mastic resin and its main compound α-pinene, known for inhibiting acetylcholinesterase in vitro.

METHODS

The inhibitory effects of freshly prepared mastic resin extract oil and α-pinene oil on acetylcholinesterase (AChE) activity were measured in vitro. Eighty healthy participants were recruited and divided into two groups: exposed to mastic resin volatiles (n = 40) or α-pinene volatiles (n = 40). Saliva samples were collected pre, during and post exposure to analyze saliva flow rate, spinnbarkeit, ion composition and MUC5B levels.

RESULTS

Mastic resin extract oil and α-pinene oil inhibited AChE activity by 207 % and 22 %, respectively. Olfactory stimulation with these volatiles significantly increased saliva secretion rate without altering spinnbarkeit and ion composition. Salivary MUC5B concentration rose after exposure to mastic resin volatiles.

CONCLUSIONS

Olfactory stimulation with mastic resin and α-pinene volatiles demonstrated a bona fide in vivo effect on saliva secretion, confirming their sialagogic capability, potentially as a result of local glandular AChE inhibition. These findings highlight the therapeutic potential of both volatile compounds in treating patients with xerostomia and hyposalivation through olfactory exposure.

Probiotics Partly Suppress the Impact of Sugar Stress on the Oral Microbiota-A Randomized, Double-Blinded, Placebo-Controlled Trial

The aim was to test if probiotics counteract oral dysbiosis during 14 days of sugar stress and subsequently help restore oral homeostasis. Eighty healthy individuals received either probiotics (n = 40) or placebo lozenges (n = 40) for 28 days and rinsed with a 10% sucrose solution 6-8 times during the initial 14 days of the trial. Saliva and supragingival samples were collected at baseline, day 14, and day 28. Saliva samples were analyzed for levels of pro-inflammatory cytokines, albumin, and salivary enzyme activity. The supragingival microbiota was characterized according to the Human Oral Microbiome Database. After 14 days of sugar stress, the relative abundance of Porphyromonas species was significantly higher (p = 0.03) and remained significantly elevated at day 28 in the probiotic group compared to the placebo group (p = 0.004). At day 28, the relative abundance of Kingella species was significantly higher in the probiotic group (p = 0.03). Streptococcus gordinii and Neisseria elongata were associated with the probiotic group on day 28, while Streptococcus sobrinus was associated with the placebo group on day 14 and day 28. On day 28, the salivary albumin level was significantly lower in the probiotic group. The present study demonstrates a potential stabilizing effect on the supragingival microbiota mediated by consumption of probiotics during short-term sugar stress.

Probiotics Support Resilience of the Oral Microbiota during Resolution after Experimental Gingivitis-A Randomized, Double-Blinded, Placebo-Controlled Trial

The present study aims to test whether probiotics protect against experimental gingivitis incited by 14 days of oral hygiene neglect and/or subsequently support the restoration of oral homeostasis. Eighty systemically and orally healthy participants refrained from oral hygiene procedures for 14 days, followed by 14 days with regular oral hygiene procedures. Additionally, participants consumed either probiotics (n = 40) or placebo (n = 40) throughout the trial. At baseline, day 14, and day 28, supragingival plaque score and bleeding-on-probing percentage (BOP %) were registered, and supragingival plaque and saliva samples were collected. The supragingival microbiota was characterized using 16S sequencing, and saliva samples were analyzed for levels of pro-inflammatory cytokines and proteases. At day 28, the relative abundance of Lautropia (p = 0.014), Prevotella (p = 0.046), Fusobacterium (p = 0.033), and Selenomonas (p = 0.0078) genera were significantly higher in the placebo group compared to the probiotics group, while the relative abundance of Rothia (p = 0.047) species was associated with the probiotics group. Streptococcus sanguinis was associated with the probiotics group, while Campylobacter gracilis was associated with the placebo group. No difference was observed in salivary cytokines, albumin, or any enzyme activity. The present study suggests that probiotics support the resilience of the oral microbiota in the resolution period after gingivitis.

Differential Modulation of Saliva-Derived Microcosm Biofilms by Antimicrobial Peptide LL-31 and D-LL-31

Microbiome modulation, aiming to restore a health-compatible microbiota, is a novel strategy to treat periodontitis. This study evaluated the modulation effects of antimicrobial peptide LL-31 and its D-enantiomer (D-LL-31) on saliva-derived microcosm biofilms, spiked with or without Porphyromonas gingivalis. To this end, one-day-old biofilms were incubated for 24 h with biofilm medium alone, or medium containing 40 µM LL-31 or D-LL-31, after which biofilms were grown for 5 days. Biofilms were assessed at 1 day and 5 days after intervention for the total viable cell counts, dipeptidyl peptidase IV (DPP4) activity, P. gingivalis amount (by qPCR) and microbial composition (by sequencing). The results showed that D-LL-31, not LL-31, significantly reduced the total viable cell counts, the P. gingivalis amount, and the DPP4 activity of the biofilms spiked with P. gingivalis, but only at 1 day after intervention. In the biofilms spiked with P. gingivalis, D-LL-31 tended to reduce the α-diversity and the compositional shift of the biofilms in time as compared to the control and LL-31 groups. In conclusion, D-LL-31 showed a better performance than LL-31 in biofilm modulation. The biofilm modulation function of the peptides could be impaired when the biofilms were in a severely dysbiotic state.

Current and Potential Applications of Monoterpenes and Their Derivatives in Oral Health Care

Plant products have been employed in medicine for centuries. As the world becomes more health-conscious, there is a growing interest in natural and minimally processed products for oral health care. This has led to an increase in research into the bioactive compounds found in plant products, particularly monoterpenes. Monoterpenes are known to have beneficial biological properties, but the specific mechanisms by which they exert their effects are not yet fully understood. Despite this, some monoterpenes are already being used in oral health care. For example, thymol, which has antibacterial properties, is an ingredient in varnish used for caries prevention. In addition to this, monoterpenes have also demonstrated antifungal, antiviral, and anti-inflammatory properties, making them versatile for various applications. As research continues, there is potential for even more discoveries regarding the benefits of monoterpenes in oral health care. This narrative literature review gives an overview of the biological properties and current and potential applications of selected monoterpenes and their derivatives in oral health care. These compounds demonstrate promising potential for future medical development, and their applications in future research are expected to expand.

Effects of Escherichia coli LPS Structure on Antibacterial and Anti-Endotoxin Activities of Host Defense Peptides

The binding of Host Defense Peptides (HDPs) to the endotoxin of Gram-negative bacteria has important unsolved aspects. For most HDPs, it is unclear if binding is part of the antibacterial mechanism or whether LPS actually provides a protective layer against HDP killing. In addition, HDP binding to LPS can block the subsequent TLR4-mediated activation of the immune system. This dual activity is important, considering that HDPs are thought of as an alternative to conventional antibiotics, which do not provide this dual activity. In this study, we systematically determine, for the first time, the influence of the O-antigen and Lipid A composition on both the antibacterial and anti-endotoxin activity of four HDPs (CATH-2, PR-39, PMAP-23, and PMAP36). The presence of the O-antigen did not affect the antibacterial activity of any of the tested HDPs. Similarly, modification of the lipid A phosphate (MCR-1 phenotype) also did not affect the activity of the HDPs. Furthermore, assessment of inner and outer membrane damage revealed that CATH-2 and PMAP-36 are profoundly membrane-active and disrupt the inner and outer membrane of Escherichia coli simultaneously, suggesting that crossing the outer membrane is the rate-limiting step in the bactericidal activity of these HDPs but is independent of the presence of an O-antigen. In contrast to killing, larger differences were observed for the anti-endotoxin properties of HDPs. CATH-2 and PMAP-36 were much stronger at suppressing LPS-induced activation of macrophages compared to PR-39 and PMAP-23. In addition, the presence of only one phosphate group in the lipid A moiety reduced the immunomodulating activity of these HDPs. Overall, the data strongly suggest that LPS composition has little effect on bacterial killing but that Lipid A modification can affect the immunomodulatory role of HDPs. This dual activity should be considered when HDPs are considered for application purposes in the treatment of infectious diseases.

Immunohistological profiling confirms salivary gland-like nature of the tubarial glands and suggests closest resemblance to the palatal salivary glands

BACKGROUND AND PURPOSE

High label uptake in 68 Ga-PSMA-11 PET/CT recently identified a bilateral nasopharyngeal structure as a salivary gland (SG)-like additional 'area of interest', to be considered in conditions affecting SGs. These structures were termed 'tubarial glands'. We aimed to further characterize their histological and immunohistochemical position compared to established SGs.

METHODS

Tubarial gland tissue was compared with parotid, submandibular, sublingual, palatal and labial SGs tissue using immunohistological techniques.

RESULTS

Expression of acinar cell-associated aquaporin-5 (AQP5) was detected in tubarial glands, in an apical location associated in control, established SGs with polarized, secretory acinar cells. Keratin14 (KRT14) expression in cells peripheral to AQP5+ clusters also suggested presence of myoepithelial cells. α-amylase, prolactin-induced protein, proline rich protein Haelll subfamily 2, and Muc5B expression suggests mucous acinar cell presence, and presence of muco-serous acinar cells peripheral to putative mucous acinar cells. Expression of adrenergic receptor-β1 by acinar-like cells of the tubarial gland suggests ability to transduce sympathetic neuronal signaling. In terms of ductal architecture, tubarial glands contained large excretory-like ducts (similar to all other SGs), and squamous ducts, comprised of intermingled KRT14+ and KRT7+ cells. These squamous ducts were also observed in palatal, sublingual and labial SGs. No striated or intercalated ducts were observed, similar to palatal SGs.

CONCLUSION

Based on histological and immunohistochemical analyses, the tubarial glands resemble SGs. They most convincingly echo characteristics of the palatal SGs in terms of ductal cells, and both the palatal and labial SGs when considering acinar cells.

Use and efficacy of dry-mouth interventions in Sjögren's disease patients and possible association with perceived oral dryness and patients' discomfort

OBJECTIVES

Sjögren's disease (SjD) patients use various interventions to relief their oral dryness. However, the use and efficacy of these interventions have only partially been evaluated. The present study aims to investigate whether there is an association between the perceived oral dryness and discomfort of SjD patients and their use of specific interventions.

MATERIALS AND METHODS

A cross-sectional study was performed among SjD patients, who completed several questionnaires to assess the severity of their oral dryness and an inventory of dry-mouth interventions. The perceived efficacy of each intervention was reported on a 5-point Likert-scale.

RESULTS

The questionnaires were returned by 92 SjD patients. For relief of oral dryness, they mostly used "eating fruit", "drinking tea", "moistening the lips", "drinking water, and "drinking small volumes" (> 50%). Three interventions had a frequency of use ranging from 2-6 times/day, whereas, "drinking water" and "drinking small volumes" showed higher frequencies (> 14). The highest overall efficacy (≥ 3.5) was reported for "chewing gum" and "using a mouth gel". Furthermore, various dry-mouth interventions showed significant associations with oral dryness scores and/or patients' discomfort. For example, "drinking small volumes" and "using XyliMelts" were associated with the Bother Index score.

CONCLUSION

Great variation was found in the use of dry-mouth interventions by the participants and the severity of the oral dryness and/or patients' discomfort seemed to affect their choice of intervention. Notably, the mostly used interventions did not show the highest reported efficacy.

CLINICAL RELEVANCE

These findings might help SjD patients and clinicians in their choice of effective dry-mouth interventions.

[A PhD completed. General conclusions of doctoral research into regional mouth dryness]

Dry mouth has a complex aetiology which makes proper diagnosis complicated. Until now, dry mouth diagnosis has mainly focused on the overall oral dryness, without taking into account regional differences within the mouth. This research showed, among other things, that there are unique patterns of oral dryness, each with its own cause. For example, patients suffering from Sjogren's syndrome mainly experienced dryness of the posterior of the palate. Patients with dry mouth due to the side effects of medication, in contrast, experienced the front part of the tongue as the driest. These findings suggest that mapping of intraoral dryness may be a useful diagnostic tool to differentiate between possible causes of dry mouth.

Comparing SARS-CoV-2 Viral Load in Human Saliva to Oropharyngeal Swabs, Nasopharyngeal Swabs, and Sputum: A Systematic Review and Meta-Analysis

A systematic review and meta-analysis were conducted to investigate the SARS-CoV-2 viral load in human saliva and compared it with the loads in oropharyngeal swabs, nasopharyngeal swabs, and sputum. In addition, the salivary viral loads of symptomatic and asymptomatic COVID-19 patients were compared. Searches were conducted using four electronic databases: PubMed, Embase, Scopus, and Web of Science, for studies published on SARS-CoV-2 loads expressed by CT values or copies/mL RNA. Three reviewers evaluated the included studies to confirm eligibility and assessed the risk of bias. A total of 37 studies were included. Mean CT values in saliva ranged from 21.5 to 39.6 and mean copies/mL RNA ranged from 1.91 × 101 to 6.98 × 1011. Meta-analysis revealed no significant differences in SARS-CoV-2 load in saliva compared to oropharyngeal swabs, nasopharyngeal swabs, and sputum. In addition, no significant differences were observed in the salivary viral load of symptomatic and asymptomatic COVID-19 patients. We conclude that saliva specimen can be used as an alternative for SARS-CoV-2 detection in oropharyngeal swabs, nasopharyngeal swabs, and sputum.

The applications of carbon dots in oral health: A scoping review

OBJECTIVES

This scoping review aims to provide an overview of the research and potential applications of carbon dots (CDs) for oral health purposes.

DESIGN

Systematic literature searches were performed on PubMed and Web of Science databases (up to February 2023). Two co-authors selected the published works independently and extracted the data in accordance with the PRISMA statement. Studies with the application of CDs for oral health purposes were included.

RESULTS

Among 152 articles, 19 articles were finally selected. Eight studies investigated the anti-microbial effects of CDs against, for example, oral pathogens, eight studies explored the applicability of CDs in relation to oral cancer, and three studies investigated CDs in relation to cell differentiation and tissue regeneration in oral health. The studies showed the promising potential of CDs in oral health, particularly for inducing bacterial killing by increasing reactive oxygen species, killing oral cancer cells via photodynamic therapeutic effects, and inducing dental pulp and periodontal bone regeneration.

CONCLUSION

The findings show that CDs have the potential to be utilized in the future for various oral health purposes. Besides, these results underline the broad-spectrum applicability of CDs, crossing the borders of oral health.

Localization and expression profiles of gingival monocyte chemoattractant protein-1-induced protein-1 (MCPIP-1) and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT-1)

OBJECTIVES

The purposes of this study were to localize monocyte chemoattractant protein-1-induced protein-1 (MCPIP-1) and its suppressor mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT-1) in gingival tissues and to profile their protein expression levels in relation to the clinical inflammation, Porphyromonas gingivalis colonization, and interleukin (IL)-8 levels.

MATERIALS AND METHODS

Study samples were collected from two independent study populations: (1) Gingival tissues were collected from eight periodontally healthy individuals and eight periodontitis patients to localize MCPIP-1 and MALT-1 immunohistochemically, and (2) forty-one gingival tissue samples with marginal, mild, or moderate to severe inflammation were collected from 20 periodontitis patients to determine MCPIP-1 and MALT-1 levels using immunoblots, P. gingivalis levels with qPCR, P. gingivalis gingipain activities with fluorogenic substrates, and IL-8 levels with multiplex technique.

RESULTS

MCPIP-1 was detectable in the epithelium and in connective tissue, being especially prominent around the blood vessel walls in healthy periodontal tissues. MALT-1 was observed at all layers of gingival epithelium and especially around the accumulated inflammatory cells in connective tissue. No difference in gingival tissue MCPIP-1 and MALT-1 levels was observed in relation to the severity of gingival inflammation. MALT-1 levels were elevated (p = 0.023) with the increase in tissue P. gingivalis levels, and there was an association between MALT-1 and IL-8 levels (β = 0.054, p = 0.001).

CONCLUSIONS

Interactions of MALT-1 levels with gingival tissue P. gingivalis counts and IL-8 levels suggest that activation of MALT-1 can take part in P. gingivalis-regulated host immune responses.

CLINICAL RELEVANCE

Pharmacological targeting the crosstalk between immune response and MCPIP-1/MALT-1 may have benefits in periodontal treatment.

Carbon quantum dots as immune modulatory therapy in a Sjögren's syndrome mouse model

OBJECTIVES

The objective of the study was to evaluate the therapeutic effects of carbon quantum dots (CQDs) in immunomodulation on non-obese diabetic (NOD) mice, as the model for Sjögren's syndrome (SS).

METHODS

Carbon quantum dots were generated from Setaria viridis via a hydrothermal process. Their toxic effects were tested by cell viability and blood chemistry analysis, meanwhile therapeutic effects were investigated in NOD mice in the aspects of saliva flow, histology, and immune cell distribution.

RESULTS

Carbon quantum dots, with rich surface chemistry and unique optical properties, showed non-cytotoxicity in vitro or no damage in vivo. Intravenously applied CQDs alleviated inflammation in the submandibular glands in NOD mice after 6-week treatments. The inflammatory area index and focus score were significantly decreased in CQD-treated mice. Besides, the levels of anti-SSA and anti-SSB were decreased in the presence of CQDs. The stimulated saliva flow rates and weight of submandibular glands were significantly increased in CQD-treated mice by reducing the apoptosis of cells. The CD3⁺ and CD4⁺ T cells distributed around the ducts of submandibular glands were significantly decreased, while the percentage of Foxp3⁺ cells was higher in CQD-treated mice than that in the control group.

CONCLUSIONS

Our findings suggest that CQDs may ameliorate the dysregulated immune processes in NOD mice.

Identification and Characterization of MUC5B Binding Peptides by Phage Display

OBJECTIVES

MUC5B plays a multifactorial role in oral health. As a consequence, decreased MUC5B output leads to impaired salivary functions and xerostomia. Synthetic combinatorial technologies have been used to develop functional peptide libraries by phage display e.g. for therapeutic purposes. In this light, our primary aim was to identify peptide sequences with specific selectivity for salivary MUC5B in vitro using phage display. Our secondary aims were to analyze their effect on salivary spinnbarkeit in situ and their effect on acid-induced demineralization in vitro.

METHODS

MUC5B binding phages were selected by phage display. Peptide affinity to MUC5B was evaluated using MUC5B coated hydroxyapatite (HA) granules. The MUC5B binding peptides (MBPs) were then examined for their effects on salivary spinnbarkeit and protective effect on acid-induced demineralization in vitro. A competitive ELISA was performed to identify the binding epitope on MUC5B using F2, a MUC5B specific antibody.

RESULTS

MBP-12 and MBP-14 displayed the highest affinity to MUC5B. MBP-12 mildly stabilized the spinnbarkeit of serous saliva after overnight incubation and of mucous saliva at all timepoints tested. The addition of MBP-12 to a pellicle of unstimulated saliva on HA discs showed no additive protective effect against acid-induced demineralization. Epitope characterization suggested sulfo-Lewis^a SO3-3Gal_1-3GlcNAc (galactose residue) as MBP-12 binding site on MUC5B.

CONCLUSIONS

The use of phage display in generating MBPs was successful. Characterization of the MBPs revealed a mild effect on spinnbarkeit in case of mucous saliva. Possibly, combinatorial peptide libraries might contribute to the development of novel formulations to treat xerostomia.

The effect of Phytosphingosine and bioactive glass-ceramics in preventing dental enamel erosion

This study evaluated the effect of phytosphingosine (PHS) and bioactive glass-ceramic (Biosilicate) on dental enamel in terms of color alteration (ΔE), microhardness, and surface roughness when submitted to erosive challenge (EC). Sixty specimens of bovine teeth (6×6×2mm) were obtained. Initial color (Easyshade, VITA), KHN (HMV-2, Shimadzu), and Ra (SJ-201P, Mitutoyo) measurements were performed. Specimens were separated into groups according to treatments: PHS, 10% Biosilicate, PHS+10% Biosilicate, and artificial saliva (control) and submitted to EC with Coca-Cola for 2 min. This cycle was repeated 4 times daily/15 days. Between cycles, specimens remained in artificial saliva (2 h/37°C). After daily cycles, they were also stored in artificial saliva at 37ºC. Final color, microhardness, and surface roughness measurements were done. Color and KHN data were analyzed by one-way ANOVA, Tukey's test; and Ra, by 2-way ANOVA, repeated measures, and Tukey's test (p<.05). The highest ΔE occurred in Saliva+EC (p<.05). Groups treated with PHS presented lower color change than Saliva+EC (p<.05). All the groups presented mean values above the 50:50% perceptibility (50:50%PT) and acceptability (50:50%AT) thresholds, except for control that showed mean value above 50:50%PT but below 50:50%AT. Biosilicate+EC showed higher relative microhardness than Saliva+EC (p<.05), but was similar to PHS+EC and PHS+Biosilicate+EC. Final enamel surface roughness increased for all the groups (p<.05), except for the control. The Biosilicate may prevent enamel mineral loss induced by erosion better than saliva. The PHS associated or not to Biosilicate demonstrated better color stability than saliva.

In vitro and in vivo toxicological evaluation of carbon quantum dots originating from Spinacia oleracea

Food-derived carbon quantum dots (CQDs) can relatively easily be synthesized and chemically manipulated for a broad spectrum of biomedical applications. However, their toxicity may hinder their actual use. Here, Spinacia oleracea-derived CQDs i.e., CQD-1 and CQD-2, were synthesized by means of different shredding methods and followed by a microwave-assisted hydrothermal approach. Subsequently, these CQDs were analyzed in vitro and in an in vivo mice model to test their biocompatibility and potential use as bioimaging agents and for activation of osteogenic differentiation. When comparing CQD-1 and CQD-2, it was found that CQD-1 exhibited 7.6 times higher photoluminescent (PL) emission intensity around 411 nm compared to CQD-2. Besides, it was found that the size distribution of CQD-1 was 2.05 ± 0.08 nm, compared with 2.14 ± 0.04 nm for CQD-2. Upon exposure to human bone marrow-derived mesenchymal stem cells (hBMSCs) in vitro, CQD-1 was endocytosed into the cytoplasm and significantly increased the differentiation of hBMSCs up to 10 μg mL^-1 after 7 and 14 days. Apparently, the presence of relatively low doses of CQD-1 showed virtually no toxic or histological effects in the major organs in vivo. In contrast, high doses of CQD-1 (1 mg mL^-1) caused cell death in vitro ranging from 35% on day 1 to 80% on day 3 post-exposure, and activated the apoptotic machinery and increased lymphocyte aggregates in the liver tissue. In conclusion, S. oleracea-derived CQDs have the potential for biomedical applications in bioimaging and activation of stem cells osteogenic differentiation. Therefore, it is postulated that CQD-1 from S. oleracea remains potential prospective material at appropriate doses and specifications.

Mechanisms of Porphyromonas gingivalis to translocate over the oral mucosa and other tissue barriers

Introduction

The oral pathogen Porphyromonas gingivalis is not only associated with periodontitis but also with systemic diseases elsewhere in the body. The mechanisms by which P. gingivalis travels from the oral cavity to other organs in the body are largely unknown. This review describes the four putative mechanisms supported by experimental evidence, which enable translocation of P. gingivalis over the oral mucosa, endothelial barriers and subsequent dissemination into the bloodstream.

Mechanisms

The first mechanism: proteolytic enzymes secreted by P. gingivalis degrade adhesion molecules between tissue cells, and the extracellular matrix. This weakens the structural integrity of the mucosa and allows P. gingivalis to penetrate the tissue. The second is transcytosis: bacteria actively enter tissue cells and transfer to the next layer or the extracellular space. By travelling from cell to cell, P. gingivalis reaches deeper structures. Thirdly, professional phagocytes take up P. gingivalis and travel to the bloodstream where P. gingivalis is released. Lastly, P. gingivalis can adhere to the hyphae forming Candida albicans. These hyphae can penetrate the mucosal tissue, which may allow P. gingivalis to reach deeper structures.

Conclusion

More research could elucidate targets to inhibit P. gingivalis dissemination and prevent the onset of various systemic diseases.

Lactoferrin and the development of salivary stones: a pilot study

Salivary stones (sialoliths) are calcified structures located in the ductal system of the major salivary glands. Their exact cause is not clear but in general they are characterized by concentric inorganic (hydroxyapatite) layers. The formation is a slow intermittent process which may result in enlargement of the sialolith causing obstruction of saliva secretion resulting in mealtime related pain and swelling of the affected salivary gland. Various studies reported the presence of organic material such as proteins and lipids in the core of sialoliths. In the present study the protein composition of twenty submandibular sialoliths was analyzed. It was found that proteins contributed on average 5% to the dry weight of submandibular stones whereby small salivary stones contained more extractable proteins than large salivary stones. Using a combination of SDS-PAGE gel electrophoresis and Western blotting, we identified α-amylase (in all stones; 100%), lysozyme (95%), lactoferrin (85%), secretory-IgA (75%), MUC7 (60%), complement C4 (60%) and C-reactive protein (35%). The presence, and the combinations, of lactoferrin, lysozyme, s-IgA and α-amylase in sialoliths was confirmed by ELISA. The gradually increasing size of a sialolith might provoke a local inflammatory response in the duct of the submandibular gland whereby the relatively low concentrations of lactoferrin and lysozyme may originate from neutrophils. The interaction of lactoferrin with s-IgA could contribute to the accumulation of lactoferrin in sialoliths. In summary, these results suggest a new pathophysiological role for lactoferrin, in the formation of sialoliths.

Direct preparation of solid carbon dots by pyrolysis of collagen waste and their applications in fluorescent sensing and imaging

The fluorescent carbon dots (CDs) have found their extensive applications in sensing, bioimaging, and photoelectronic devices. In general terms, the synthesis of CDs is straight-forward, though their subsequent purification can be laborious. Therefore, there is a need for easier ways to generate solid CDs with a high conversion yield. Herein, we used collagen waste as a carbon source in producing solid CDs through a calcination procedure without additional chemical decomposition treatment of the raw material. Considering a mass of acid has destroyed the original protein macromolecules into the assembled structure with amino acids and peptide chains in the commercial extraction procedure of collagen product. The residual tissues were assembled with weak intermolecular interactions, which would easily undergo dehydration, polymerization, and carbonization during the heat treatment to produce solid CDs directly. The calcination parameters were surveyed to give the highest conversion yield at 78%, which occurred at 300°C for 2 h. N and S atomic doping CDs (N-CDs and S-CDs) were synthesized at a similar process except for immersion of the collagen waste in sulfuric acid or nitric acid in advance. Further experiments suggested the prepared CDs can serve as an excellent sensor platform for Fe³⁺ in an acid medium with high anti-interference. The cytotoxicity assays confirmed the biosafety and biocompatibility of the CDs, suggesting potential applications in bioimaging. This work provides a new avenue for preparing solid CDs with high conversion yield.

Correlations of palatal surface area with anthropometric dimensions of the head and face

Purpose

Saliva distribution over the palatal surface plays an important role in the perception of dry mouth. It is envisaged that non-invasive estimation of the palatal surface area by anthropometric measurements of the head and face can be useful in the assessment of oral dryness. For this purpose, the relationship between the palatal surface area and anthropometric measurements of the head and face was investigated.

Methods

The palatal surface was measured in 51 healthy volunteers using an intra-oral scanner. The distances between anthropometric landmarks of the head and face were determined using an anatomical sliding caliper. Correlations between the palatal surface area and the anthropometric landmarks were investigated.

Results

The median palatal surface area for the total study population was found to be 2120.6 mm². Virtually, all anthropometric measurements showed significant differences between females and males. Various head and face measurements had a significant correlation with the palatal surface area. However, these correlations disappeared when the participants were stratified based on their sex, with the exception of mandibular length and palatal width in females.

Conclusion

The surface area of the palate correlates with nearly all anthropometric measurements of the head and face included in this study. Yet, the clinical applicability seems limited to females.

Novel Antiamoebic Tyrocidine-Derived Peptide against Brain-Eating Amoebae

Acanthamoeba castellanii (A. castellanii) can cause Acanthamoeba keratitis, a sight-threatening infection, as well as a fatal brain infection termed granulomatous amoebic encephalitis, mostly in immunocompromised individuals. In contrast, Naegleria fowleri (N. fowleri) causes a deadly infection involving the central nervous system, recognized as primary amoebic encephalitis, mainly in individuals partaking in recreational water activities or those with nasal exposure to contaminated water. Worryingly, mortality rates due to these infections are more than 90%, suggesting the need to find alternative therapies. In this study, antiamoebic activity of a peptide based on the structure of the antibiotic tyrocidine was evaluated against A. castellanii and N. fowleri. The tyrocidine-derived peptide displayed significant amoebicidal efficacy against A. castellanii and N. fowleri. At 250 μg/mL, the peptide drastically reduced amoebae viability up to 13% and 21% after 2 h of incubation against N. fowleri and A. castellanii., whereas, after 24 h of incubation, the peptide showed 86% and 94% amoebicidal activity against A. castellanii and N. fowleri. Furthermore, amoebae pretreated with 100 μg/mL peptide inhibited 35% and 53% A. castellanii and N. fowleri, while, at 250 μg/mL, 84% and 94% A. castellanii and N. fowleri failed to adhere to human cells. Amoeba-mediated cell cytopathogenicity assays revealed 31% and 42% inhibition at 100 μg/mL, while at 250 μg/mL 75% and 86% A. castellanii and N. fowleri were inhibited. Assays revealed inhibition of encystation in both A. castellanii (58% and 93%) and N. fowleri (73% and 97%) at concentrations of 100 and 250 μg/mL respectively. Importantly, tyrocidine-derived peptide depicted minimal cytotoxicity to human cells and, thus, may be a potential candidate in the rational development of a treatment regimen against free-living amoebae infections. Future studies are necessary to elucidate the in vivo effects of tyrocidine-derived peptide against these and other pathogenic amoebae of importance.

Gramicidin A is hydrolyzed by a d-stereospecific peptidase produced by Bacillus anthracis

Previously we described the discovery of a Bacillus spp. specific peptidase activity related to d-stereospecific peptidases (DSPs). The peptidase showed a strong preference for d-leucine and d-valine amino acids. These amino acids are present in the structure of the non-ribosomal peptide (NRP) antibiotics gramicidin A, B and C and polymyxin E. To examine if the Bacillus spp. DSP-related peptidase can hydrolyze these NRPs, the effect of gramicidin A and C and polymyxin E on peptidase activity in Bacillus anthracis culture supernatant was monitored. It was found that both gramicidins inhibited the DSP-related activity in a competitive manner. MALDI-TOF analysis revealed that upon incubation with B. anthracis culture supernatant gramicidin A hydrolyzation products appeared. This study shows that the Bacillus spp. specific DSP-like peptidase was potentially produced by the bacteria to gain intrinsic resistance against NRP antibiotics. These results are of utmost importance in research towards antimicrobial resistance, whereas transfer of DSP-related activity to other clinically relevant pathogens can be a serious threat to human health.

Identification of VEGFR2 as the Histatin-1 receptor in endothelial cells

Histatin-1 is a salivary peptide with antimicrobial and wound healing promoting activities, which was previously shown to stimulate angiogenesis in vitro and in vivo via inducing endothelial cell migration. The mechanisms underlying the proangiogenic effects of Histatin-1 remain poorly understood and specifically, the endothelial receptor for this peptide, is unknown. Based on the similarities between Histatin-1-dependent responses and those induced by the prototypical angiogenic receptor, vascular endothelial growth factor receptor 2 (VEGFR2), we hypothesized that VEGFR2 is the Histatin-1 receptor in endothelial cells. First, we observed that VEGFR2 is necessary for Histatin-1-induced endothelial cell migration, as shown by both pharmacological inhibition studies and siRNA-mediated ablation of VEGFR2. Moreover, Histatin-1 co-immunoprecipitated and co-localized with VEGFR2, associating spatial proximity between these proteins with receptor activation. Indeed, pulldown assays with pure, tagged and non-tagged proteins showed that Histatin-1 and VEGFR2 directly interact in vitro. Optical tweezers experiments permitted estimating kinetic parameters and rupture forces, indicating that the Histatin-1-VEGFR2 interaction is transient, but specific and direct. Sequence alignment and molecular modeling identified residues Phe26, Tyr30 and Tyr34 within the C-terminal domain of Histatin-1 as relevant for VEGFR2 binding and activation. This was corroborated by mutation and molecular dynamics analyses, as well as in direct binding assays. Importantly, these residues were required for Histatin-1 to induce endothelial cell migration and angiogenesis in vitro. Taken together, our findings reveal that VEGFR2 is the endothelial cell receptor of Histatin-1 and provide insights to the mechanism by which this peptide promotes endothelial cell migration and angiogenesis.

Natural and Synthetic Sortase A Substrates Are Processed by Staphylococcus aureus via Different Pathways

Endogenous Staphylococcus aureus sortase A (SrtA) covalently incorporates cell wall anchored proteins equipped with a SrtA recognition motif (LPXTG) via a lipid II-dependent pathway into the staphylococcal peptidoglycan layer. Previously, we found that the endogenous S. aureus SrtA is able to recognize and process a variety of exogenously added synthetic SrtA substrates, including K(FITC)LPMTG-amide and K(FITC)-K-vancomycin-LPMTG-amide. These synthetic substrates are covalently incorporated into the bacterial peptidoglycan (PG) of S. aureus with varying efficiencies. In this study, we examined if native and synthetic substrates are processed by SrtA via the same pathway. Therefore, the effect of the lipid II inhibiting antibiotic bacitracin on the incorporation of native and synthetic SrtA substrates was assessed. Treatment of S. aureus with bacitracin resulted in a decreased incorporation of protein A in the bacterial cell wall, whereas incorporation of exogenous synthetic substrates was increased. These results suggest that natural and exogenous synthetic substrates are processed by S. aureus via different pathways.

Scavenging of bacteria or bacterial products by magnetic particles functionalized with a broad-spectrum pathogen recognition receptor motif offers diagnostic and therapeutic applications

Sepsis is a dysregulated host response of severe bloodstream infections, and given its frequency of occurrence and high mortality rate, therapeutic improvements are imperative. A reliable biomimetic strategy for the targeting and separation of bacterial pathogens in bloodstream infections involves the use of the broad-spectrum binding motif of human GP-340, a pattern-recognition receptor of the scavenger receptor cysteine rich (SRCR) superfamily that is expressed on epithelial surfaces but not found in blood. Here we show that these peptides, when conjugated to superparamagnetic iron oxide nanoparticles (SPIONs), can separate various bacterial endotoxins and intact microbes (E. coli, S. aureus, P. aeruginosa and S. marcescens) with high efficiency, especially at low and thus clinically relevant concentrations. This is accompanied by a subsequent strong depletion in cytokine release (TNF, IL-6, IL-1β, Il-10 and IFN-γ), which could have a direct therapeutic impact since escalating immune responses complicates severe bloodstream infections and sepsis courses. SPIONs are coated with aminoalkylsilane and capture peptides are orthogonally ligated to this surface. The particles behave fully cyto- and hemocompatible and do not interfere with host structures. Thus, this approach additionally aims to dramatically reduce diagnostic times for patients with suspected bloodstream infections and accelerate targeted antibiotic therapy. STATEMENT OF SIGNIFICANCE: Sepsis is often associated with excessive release of cytokines. This aspect and slow diagnostic procedures are the major therapeutic obstacles. The use of magnetic particles conjugated with small peptides derived from the binding motif of a broad-spectrum mucosal pathogen recognition protein GP-340 provides a highly efficient scavenging platform. These peptides are not found in blood and therefore are not subject to inhibitory mechanisms like in other concepts (mannose binding lectine, aptamers, antibodies). In this work, data are shown on the broad bacterial binding spectrum, highly efficient toxin depletion, which directly reduces the release of cytokines. Host cells are not affected and antibiotics not adsorbed. The particle bound microbes can be recultured without restriction and thus be used directly for diagnostics.

Preferences of Sjögren's syndrome patients regarding potential new saliva substitutes

OBJECTIVES

Sjögren's syndrome (SS) patients should be involved in the development of new saliva substitutes at an early stage. The purpose of the current study was to explore the preferences of these patients regarding various product characteristics of potential new saliva substitutes.

MATERIAL AND METHOD

A questionnaire was distributed among SS patients. They could anonymously indicate their preferences for saliva substitute characteristics using 5-point Likert scales.

RESULTS

Fifty-nine SS patients filled in the questionnaire. According to their opinion, the most ideal saliva substitute has a thin-watery consistency with a neutral flavour that should be applied as a spray. Patients demand a prolonged alleviation of dry mouth complaints and neutralization of harmful bacteria. The patients mainly object against the presence of artificial sweeteners and alcohol in saliva substitutes, but have limited objections against the presence of vegetable-based ingredients and natural enzymes. Major objections were against the potential side effects "bitter taste" and "discoloration of teeth". Age and severity of xerostomia affected desire of flavours. Younger patients preferred menthol flavour, while respondents with severe xerostomia preferred the use of "neutral flavours" significantly more.

CONCLUSION

The most ideal saliva substitute has thin-watery consistency in spray form with a neutral flavour and providing long alleviation of dry mouth complaints. Besides, it should not contain artificial sweeteners or alcohol, and should not have a bitter taste or cause discoloration of the teeth.

CLINICAL RELEVANCE

Investigating the opinion of SS patients provides tailoured insights into their preference, which may contribute to the development of more effective saliva substitutes.

Is TIMP-1 a biomarker for periodontal disease? A systematic review and meta-analysis

Objective

One of the most important families of proteases associated with periodontal disease is the family of the matrix metalloproteinases (MMPs). Their activity is regulated by tissue inhibitors of metalloproteinases (TIMPs), and an imbalance between MMP activity and regulation by TIMPs has been associated with the progression of periodontal disease. This strong interaction between TIMPs and MMPs might be an indication that TIMPs can be used as a biomarker to monitor periodontal disease progression in oral fluids. In particular, TIMP‐1 is a frequently studied biomarker for periodontal diseases. Therefore, the aim of this systematic review was to evaluate the scientific literature regarding TIMP‐1 concentrations in oral fluids of patients suffering from periodontitis or gingivitis in comparison to healthy individuals.

Material and Methods

PubMed/ MedLine and Web of Science databases were searched electronically. Studies that met the inclusion criteria were systematically evaluated and assessed for eligibility and risk of bias. Meta‐analysis was performed through the random effects model to assess the association between periodontitis/gingivitis and TIMP‐1 concentration in stimulated saliva, unstimulated saliva, and gingival crevicular fluid (GCF).

Results

The search strategy provided a total of 322 studies of which 10 studies met all inclusion criteria. Two studies investigated TIMP‐1 concentrations in GCF, three studies in unstimulated saliva, and five studies investigated TIMP‐1 concentrations in stimulated saliva. Three studies revealed that TIMP‐1 levels in oral fluids were significantly decreased in periodontal disease. Meta‐analysis revealed that there is no statistically significant difference between TIMP‐1 concentration in oral fluids of periodontitis/gingivitis patients in comparison to healthy individuals.

Conclusions

This systematic review with meta‐analysis shows that periodontal diseases are not associated with a statistically significant change in TIMP‐1 concentration in oral fluids.

[Developments of assays in oral fluids to support diagnosis of periodontitis]

The diagnosis of periodontitis is traditionally based on clinical and radiographic examinations in combination with an anamnesis. For dentists, but possibly also for non-dental care providers, more and more other methods are being developed that could be useful for supporting currently used diagnostics as well as periodontal screening purposes. This includes the analysis of biomarkers in oral fluids such as saliva, oral rinses and gingival crevicular fluid. For example, there is a commercial test, based on the analysis of MMP-8 in oral rinses, to disprove or confirm suspicions of periodontal inflammation. In addition, recent research shows that the combination of MMP-8 and chitinase in oral rinses has superior discrimination capabilities to the analysis of MMP-8 or chitinase alone. Although diagnosis using saliva, gingival crevicular fluid and oral rinses appears to be a promising alternative for detecting periodontal inflammation, probing remains the gold standard in the oral care practice.

The association between oral dryness and use of dry-mouth interventions in Sjögren's syndrome patients

Objective

Sjögren’s syndrome patients use different dry-mouth interventions for the relieve of their oral dryness. Recently, it was shown that patients with dry-mouth complaints have regional differences in perceived intra-oral dryness. Therefore, the aim of the present study was to investigate whether the use of dry-mouth interventions is related to the perceived regional oral dryness.

Materials and methods

A cross-sectional study was performed among Sjögren’s patients. Volunteers could anonymously administer various questionnaires, including the Regional Oral Dryness Inventory (RODI), Xerostomia Inventory (XI), Bother Index (BI) and a list of dry-mouth interventions.

Results

Sjögren’s syndrome patients use a wide variety for the relieve of oral dryness. “Drinking water’’ and “moistening the lips’’ were used most frequently. Dry-mouth interventions, “drinking water’’, “rinsing of the mouth”, and “drinking small volumes” had significant associations with the RODI-scores of the posterior palate, and anterior and posterior tongue, respectively. On the other hand, “using mouth gel’’ had a significant association with the RODI-scores of the inside cheeks.

Conclusion

Sjögren’s syndrome patients are more likely to use mouth gels when their inside cheeks were experienced as most dry, while they drank water, rinsed their mouth or drank small volumes if the posterior palate, and anterior and posterior tongue were considered as dry. It can be concluded that intra-oral dryness affects dry-mouth perception and thereby also the use of the various dry-mouth interventions.

Clinical relevance

The therapeutic choice of dry-mouth interventions by Sjögren’s syndrome patients seems to some extent to be related to dryness at specific intra-oral regions.

Comparing periodontitis biomarkers in saliva, oral rinse and gingival crevicular fluid: A pilot study

AIM

To explore the feasibility of screening for periodontitis by measuring biomarkers, namely total proteolytic activity (TPA), matrix metalloproteinase (MMP)-8, chitinase, lysozyme or their combination, in saliva, oral rinse and gingival crevicular fluid (GCF).

MATERIAL AND METHODS

Subjects were recruited among healthy/gingivitis individuals and untreated periodontitis patients in Academic Centre for Dentistry Amsterdam (ACTA). All participants donated samples of unstimulated whole saliva, oral rinse and GCF. The protein concentrations and MMP-8 levels were determined by ELISA. Enzymatic activities were measured using appropriate fluorogenic substrates.

RESULTS

In oral rinse samples, periodontitis patients (n = 19) exhibited significantly higher concentrations of MMP-8 and TPA than controls (n = 20). MMP-8 in combination with chitinase explained 88% of the variance and assigned a subject to control or periodontitis group, with best accuracy (87.2%) in oral rinse.

CONCLUSIONS

The combination of MMP-8 and chitinase in the current oral rinse procedure has the potential to discriminate periodontitis from periodontal health/gingivitis.

Simple and rapid peptide nanoprobe biosensor for the detection of Legionellaceae

This study demonstrates the development of a sensitive, specific, and quantitative peptide-based nanoprobe prototype assay for the detection of Legionellaceae in a simple way and in a short time. In this work, proteases present in the culture supernatants of Legionella spp. were used as a biomarker. Fluorogenic peptide substrates, specific to Legionella strains culture supernatant proteases, were identified. Peptidases produced a significant increase in the fluorescence intensity following the cleavage of the dipeptide fluorogenic substrates. The specific substrates were identified and coupled with carboxyl-terminated nano-magnetic particles (NMPs). On the other hand, the C-terminal was conjugated with the cysteine residue to covalently integrate with a gold sensing platform via the Au-S linkage. Four different sensors were fabricated from the four specific substrates, which were treated with the protesase of six different species of Legionella. In the presence of specific protease, the peptide sequence is digested and the magnetic nanobeads moved out of the gold surface, resulting in the apparence of gold color. One of the nanoprobes sensitivity detects as low as 60 CFU mL^-1 of Legionella anisa, Legionella micdadei, and Fluoribacter dumoffii. The cross-reactivity of the sensors was tested using other closely associated bacterial species and no significant cross-reactivity of the sensors was found. It is envisaged that this assay could be useful for screening purposes or might be supportive for the fast and easy detection of Legionella protease activity for water monitoring purposes.

Lubricating properties of chewing stimulated whole saliva from patients suffering from xerostomia

OBJECTIVES

The study aimed to quantify the lubricating properties of chewing stimulated whole saliva from healthy controls (n = 22), from patients suffering from primary Sjögren's syndrome (n = 37) and from patients undergoing head-and-neck radiotherapy (n = 34).

MATERIALS AND METHODS

All participants had to complete the Xerostomia Inventory questionnaire to score dry mouth sensation. Lubrication was measured using an ex vivo tongue-enamel friction system in terms of Relief and Relief period. MUC5b and total protein concentrations of the saliva samples were measured by an enzyme-linked immunosorbent assay and a bicinchoninic acid assay, respectively.

RESULTS

Relief of Sjögren's patients' saliva and post-irradiation patients' saliva was similar compared with healthy controls, but saliva from post-irradiation patients lubricated significantly better than saliva from Sjögren's patients. The Relief period was similar between the three groups. The Relief and Relief period were higher for saliva samples post-irradiation compared to pre-irradiation. MUC5b and total protein concentrations were comparable in all groups. MUC5b and total protein output were significantly lower in patients subjected to radiotherapy compared to saliva from healthy controls and pre-irradiation patients. MUC5b concentrations positively correlated with lubricating properties of post-irradiation patient saliva.

CONCLUSIONS

The lubricating properties of patient saliva were not any worse than healthy controls. Lower flow rate leads to lower availability of saliva in the oral cavity and decreases the overall output of protein and MUC5b, which might result in an insufficient replenishing of the mucosal salivary film.

CLINICAL RELEVANCE

An insufficient replenishing might underlie the sensation of a dry mouth and loss of oral function.

LFchimera: a synthetic mimic of the two antimicrobial domains of bovine lactoferrin

Saliva is essential for the maintenance of oral health. When salivary flow is impaired, the risk of various oral diseases such as caries and candidiasis increases drastically. Under healthy conditions, saliva provides effective protection against microbial colonization by the collaborative action of numerous host-defense molecules. This review describes how saliva has been the guideline for the design and characterization of a heterodimeric antimicrobial construct called LFchimera. This construct mimics the helical parts of two antimicrobial domains in the crystal structure of bovine lactoferrin. It shows high antimicrobial activity against a broad spectrum of Gram-positive and Gram-negative bacteria, fungi, and parasites including biowarfare agents such as Bacillus anthracis, Burkholderia pseudomallei, and Yersinia pestis. Further, sublethal concentrations of LFchimera inhibited biofilm formation, the invasiveness of HeLa cells by Yersinia spp., and prevented haemolysis of enteropathogenic Escherichia coli, demonstrating the versatility of these peptides.

Histatin-1 is a novel osteogenic factor that promotes bone cell adhesion, migration, and differentiation

Histatin-1 is a salivary antimicrobial peptide involved in the maintenance of enamel and oral mucosal homeostasis. Moreover, Histatin-1 has been shown to promote re-epithelialization in soft tissues, by stimulating cell adhesion and migration in oral and dermal keratinocytes, gingival and skin fibroblasts, endothelial cells and corneal epithelial cells. The broad-spectrum activity of Histatin-1 suggests that it behaves as a universal wound healing promoter, although this is far from being clear yet. Here, we report that Histatin-1 is a novel osteogenic factor that promotes bone cell adhesion, migration, and differentiation. Specifically, Histatin-1 promoted cell adhesion, spreading, and migration of SAOS-2 cells and MC3T3-E1 preosteoblasts in vitro, when placed on a fibronectin matrix. Besides, Histatin-1 induced the expression of osteogenic genes, including osteocalcin, osteopontin, and Runx2, and increased both activity and protein levels of alkaline phosphatase. Furthermore, Histatin-1 promoted mineralization in vitro, as it augmented the formation of calcium deposits in both SAOS-2 and MC3T3-E1 cells. Mechanistically, although Histatin-1 failed to activate ERK1/2, FAK, and Akt, which are signaling proteins associated with osteogenic differentiation or cell migration, it triggered nuclear relocalization of β-catenin. Strikingly, the effects of Histatin-1 were recapitulated in cells that are nonosteogenically committed, since it promoted surface adhesion, migration, and the acquisition of osteogenic markers in primary mesenchymal cells derived from the apical papilla and dental pulp. Collectively, these observations indicate that Histatin-1 is a novel osteogenic factor that promotes bone cell differentiation, surface adhesion and migration, as crucial events required for bone tissue regeneration.

Biotribological properties of xerostomia patient saliva and its enhancement

The study aimed to quantify the lubricating properties of chewing stimulated whole saliva from healthy controls (n=22), from patients suffering from primary Sjögren’s syndrome (n=37) and from patients undergoing head-and-neck radiotherapy (n=34). Materials and Methods All participants had to complete the Xerostomia Inventory questionnaire to score dry mouth sensation. Lubrication was measured using an ex vivo tongue-enamel friction system in terms of Relief and Relief period. MUC5b and total protein concentrations of the saliva samples were measured by an enzyme-linked immunosorbent assay and a bicinchoninic acid assay, respectively. Results Relief of Sjögren’s patients saliva and post-irradiation patients saliva was similar compared with healthy controls, but saliva from post-irradiation patients lubricated significantly better than saliva from Sjögren’s patients. The Relief period was similar between the three groups. The Relief and Relief period were higher for saliva samples post-irradiation compared to pre-irradiation. MUC5b and total protein concentrations were comparable in all groups. MUC5b and total protein output were significantly lower in patients subjected to radiotherapy compared to saliva from healthy controls and pre-irradiation patients. MUC5b concentrations positively correlated with lubricating properties of post-irradiation patient saliva. Conclusions The lubricating properties of patient saliva were not any worse than healthy controls. Lower flow rate leads to lower availability of saliva in the oral cavity and decreases the overall output of protein and MUC5b, which might result in an insufficient replenishing of the mucosal salivary film. Clinical Relevance An insufficient replenishing might underlie the sensation of a dry mouth and loss of oral function. In the talk I will explain biomaterials related strategies, yet ex vivo, to enhance salivary lubrication despite of low flowrates.

Selective tumor antigen vaccine delivery to human CD169+ antigen-presenting cells using ganglioside-liposomes

Priming of CD8+ T cells by dendritic cells (DCs) is crucial for the generation of effective antitumor immune responses. Here, we describe a liposomal vaccine carrier that delivers tumor antigens to human CD169/Siglec-1+ antigen-presenting cells using gangliosides as targeting ligands. Ganglioside-liposomes specifically bound to CD169 and were internalized by in vitro-generated monocyte-derived DCs (moDCs) and macrophages and by ex vivo-isolated splenic macrophages in a CD169-dependent manner. In blood, high-dimensional reduction analysis revealed that ganglioside-liposomes specifically targeted CD14+ CD169+ monocytes and Axl+ CD169+ DCs. Liposomal codelivery of tumor antigen and Toll-like receptor ligand to CD169+ moDCs and Axl+ CD169+ DCs led to cytokine production and robust cross-presentation and activation of tumor antigen-specific CD8+ T cells. Finally, Axl+ CD169+ DCs were present in cancer patients and efficiently captured ganglioside-liposomes. Our findings demonstrate a nanovaccine platform targeting CD169+ DCs to drive antitumor T cell responses.

Human Salivary Histatin-1 Promotes Osteogenic Cell Spreading on Both Bio-Inert Substrates and Titanium SLA Surfaces

Promoting cell spreading is crucial to enhance bone healing and implant osteointegration. In this study, we investigated the stimulatory effect of human salivary histatin-1 (Hst-1) on the spreading of osteogenic cells in vitro as well as the potential signaling pathways involved. Osteogenic cells were seeded on bio-inert glass slides with or without the presence of Hst1 in dose-dependent or time-course assays. 1 scrambled and 6 truncated Hst1 variants were also evaluated. Cell spreading was analyzed using a well-established point-counting method. Fluorescent microscopy was adopted to examine the cellular uptake of fluorescently labeled Hst1 (F-Hst1) and also the cell spreading on sandblasted and acid etched titanium surfaces. Signaling inhibitors, such as U0126, SB203580, and pertussis toxin (PTx) were used to identify the potential role of extracellular-signal-regulated kinase, p38 and G protein-coupled receptor pathways, respectively. After 60 min incubation, Hst1 significantly promoted the spreading of osteogenic cells with an optimal concentration of 10 μM, while truncated and scrambled Hst1 did not. F-Hst1 was taken up and localized in the vicinity of the nuclei. U0126 and SB2030580, but not PTx, inhibited the effect of Hst1. 10 μM Hst1 significantly promoted the spreading of osteogenic cells on both bio-inert substrates and titanium SLA surfaces, which involved ERK and p38 signaling. Human salivary histatin-1 might be a promising peptide to enhance bone healing and implant osteointegration in clinic.