Effect of donor age on the concentrations of histatins in human parotid and submandibular/sublingual saliva

Interactions between systemic diseases and oral microbiota shifts in the aging community: A narrative review

As a gateway to general health and a diverse microbial habitat, the oral cavity is colonized by numerous microorganisms such as bacteria, fungi, viruses, and archaea. Oral microbiota plays an essential role in preserving oral health. Besides, the oral cavity also significantly contributes to systemic health. Physiological aging influences all body systems, including the oral microbial inhabitants. The cited effect can cause diseases by forming dysbiotic communities. Since it has been demonstrated that microbial dysbiosis could disturb the symbiosis state between the host and the resident microorganism, shifting the condition toward a more pathogenic one, this study investigated how the oral microbial shifts in aging could associate with the development or progression of systemic diseases in older adults. The current study focused on the interactions between variations in the oral microbiome and prevalent diseases in older adults, including diabetes mellitus, Sjögren's syndrome, rheumatoid arthritis, pulmonary diseases, cardiovascular diseases, oral candidiasis, Parkinson's disease, Alzheimer's disease, and glaucoma. Underlying diseases can dynamically modify the oral ecology and the composition of its resident oral microbiome. Clinical, experimental, and epidemiological research suggests the associations of systemic disorders with bacteremia and inflammation after oral microbial changes in older adults.

Top-Down Proteomics Detection of Potential Salivary Biomarkers for Autoimmune Liver Diseases Classification

(1) Autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC) are autoimmune liver diseases characterized by chronic hepatic inflammation and progressive liver fibrosis. The possible use of saliva as a diagnostic tool has been explored in several oral and systemic diseases. The use of proteomics for personalized medicine is a rapidly emerging field. (2) Salivary proteomic data of 36 healthy controls (HCs), 36 AIH and 36 PBC patients, obtained by liquid chromatography/mass spectrometry top-down pipeline, were analyzed by multiple Mann-Whitney test, Kendall correlation, Random Forest (RF) analysis and Linear Discriminant Analysis (LDA); (3) Mann-Whitney tests provided indications on the panel of differentially expressed salivary proteins and peptides, namely cystatin A, statherin, histatin 3, histatin 5 and histatin 6, which were elevated in AIH patients with respect to both HCs and PBC patients, while S100A12, S100A9 short, cystatin S1, S2, SN and C showed varied levels in PBC with respect to HCs and/or AIH patients. RF analysis evidenced a panel of salivary proteins/peptides able to classify with good accuracy PBC vs. HCs (83.3%), AIH vs. HCs (79.9%) and PBC vs. AIH (80.2%); (4) RF appears to be an attractive machine-learning tool suited for classification of AIH and PBC based on their different salivary proteomic profiles.

Antimicrobial Peptides with Anti-Candida Activity

Mycoses are accountable for millions of infections yearly worldwide. Invasive candidiasis is the most usual, presenting a high morbidity and mortality. Candida albicans remains the prevalent etiologic agent, but the incidence of other species such as Candida parapsilosis, Candida glabrata and Candida auris keeps increasing. These pathogens frequently show a reduced susceptibility to commonly used antifungal drugs, including polyenes, triazoles and echinocandins, and the incidence of emerging multi-drug-resistant strains of these species continues to increase. Therefore, the need to search for new molecules that target these pathogenic species in a different manner is now more urgent than ever. Nature is an almost endless source of interesting new molecules that could meet this need. Among these molecules, antimicrobial peptides, present in different sources in nature, possess some advantages over conventional antifungal agents, even with their own drawbacks, and are considered as a promising pharmacological option against a wide range of microbial infections. In this review, we describe 20 antimicrobial peptides from different origins that possess an activity against Candida.

Salivary Proteomics Reveals Significant Changes in Relation to Alzheimer's Disease and Aging

BACKGROUND

Aging is a risk factor for several pathologies as Alzheimer's disease (AD). Great interest exists, therefore, in discovering diagnostic biomarkers and indicators discriminating biological aging and health status. To this aim, omic investigations of biological matrices, as saliva, whose sampling is easy and non-invasive, offer great potential.

OBJECTIVE

Investigate the salivary proteome through a statistical comparison of the proteomic data by several approaches to highlight quali-/quantitative variations associated specifically either to aging or to AD occurrence, and, thus, able to classify the subjects.

METHODS

Salivary proteomic data of healthy controls under-70 (adults) and over-70 (elderly) years old, and over-70 AD patients, obtained by liquid chromatography/mass spectrometry, were analyzed by multiple Mann-Whitney test, Kendall correlation, and Random-Forest (RF) analysis.

RESULTS

Almost all the investigated proteins/peptides significantly decreased in relation to aging in elderly subjects, with or without AD, in comparison with adults. AD subjects exhibited the highest levels of α-defensins, thymosin β4, cystatin B, S100A8 and A9. Correlation tests also highlighted age/disease associated differences. RF analysis individuated quali-/quantitative variations in 20 components, as oxidized S100A8 and S100A9, α-defensin 3, P-B peptide, able to classify with great accuracy the subjects into the three groups.

CONCLUSION

The findings demonstrated a strong change of the salivary protein profile in relation to the aging. Potential biomarkers candidates of AD were individuated in peptides/proteins involved in antimicrobial defense, innate immune system, inflammation, and in oxidative stress. RF analysis revealed the feasibility of the salivary proteome to discriminate groups of subjects based on age and health status.

Point-of-care COPD diagnostics: biomarkers, sampling, paper-based analytical devices, and perspectives

Chronic obstructive pulmonary disease (COPD) has become the third leading cause of global death. Insufficiency in early diagnosis and treatment of COPD, especially COPD exacerbations, leads to a tremendous economic burden and medical costs. A cost-effective and timely prevention requires decentralized point-of-care diagnostics at patients' residences at affordable prices. Advances in point-of-care (POC) diagnostics may offer new solutions to reduce medical expenditures by measuring salivary and blood biomarkers. Among them, paper-based analytical devices have been the most promising candidates due to their advantages of being affordable, biocompatible, disposable, scalable, and easy to modify. In this review, we present salivary and blood biomarkers related to COPD endotypes and exacerbations, summarize current technologies to collect human whole saliva and whole blood samples, evaluate state-of-the-art paper-based analytical devices that detect COPD biomarkers in saliva and blood, and discuss existing challenges with outlooks on future paper-based POC systems for COPD diagnosis and management.

Astringency Sensitivity to Tannic Acid: Effect of Ageing and Saliva

Astringency is an important sensory characteristic of food and beverages containing polyphenols. However, astringency perception in elderly people has not been previously documented. The aim of the present work was to evaluate sensitivity to astringency as a function of age, salivary flow and protein amount. Fifty-four panellists, including 30 elderly people (age = 75 ± 4.2 years) and 24 young people (age = 29.4 ± 3.8 years), participated in this study. Astringency sensitivity was evaluated by the 2-alternative forced choice (2-AFC) procedure using tannic acid solutions. Whole saliva was collected for 5 min before and after the sensory tests. The results showed that the astringency threshold was significantly higher in the elderly group than the young group. No correlation was observed between the salivary protein amount and threshold value. However, a negative correlation between salivary flow and threshold was observed in the young group only. These results showed a difference in oral astringency perception as a function of age. This difference can be linked to salivary properties that differ as a function of age.

Disease-Induced Changes in Salivary Gland Function and the Composition of Saliva

Although the physiological control of salivary secretion has been well studied, the impact of disease on salivary gland function and how this changes the composition and function of saliva is less well understood and is considered in this review. Secretion of saliva is dependent upon nerve-mediated stimuli, which activate glandular fluid and protein secretory mechanisms. The volume of saliva secreted by salivary glands depends upon the frequency and intensity of nerve-mediated stimuli, which increase dramatically with food intake and are subject to facilitatory or inhibitory influences within the central nervous system. Longer-term changes in saliva secretion have been found to occur in response to dietary change and aging, and these physiological influences can alter the composition and function of saliva in the mouth. Salivary gland dysfunction is associated with different diseases, including Sjögren syndrome, sialadenitis, and iatrogenic disease, due to radiotherapy and medications and is usually reported as a loss of secretory volume, which can range in severity. Defining salivary gland dysfunction by measuring salivary flow rates can be difficult since these vary widely in the healthy population. However, saliva can be sampled noninvasively and repeatedly, which facilitates longitudinal studies of subjects, providing a clearer picture of altered function. The application of omics technologies has revealed changes in saliva composition in many systemic diseases, offering disease biomarkers, but these compositional changes may not be related to salivary gland dysfunction. In Sjögren syndrome, there appears to be a change in the rheology of saliva due to altered mucin glycosylation. Analysis of glandular saliva in diseases or therapeutic interventions causing salivary gland inflammation frequently shows increased electrolyte concentrations and increased presence of innate immune proteins, most notably lactoferrin. Altering nerve-mediated signaling of salivary gland secretion contributes to medication-induced dysfunction and may also contribute to altered saliva composition in neurodegenerative disease.

Cellular responses of histatin-derived peptides immobilized titanium surface using a tresyl chloride-activated method

Effects of histatin-derived peptides immobilization by tresyl chloride-activation technique for MC3T3-E1 cellular responses on titanium (Ti) were evaluated. MC3T3-E1 were cultured on sandblasted and acid-etched Ti disks immobilized with histatin-derived peptides, including histatin-1, JH8194, and mixed histatin-1 with JH8194. Surface topography and cellular morphology were examined using a scanning electron microscope. Elemental composition and conformational peptides on Ti surface were examined using energy dispersive X-ray and fourier transform infrared spectroscopy, respectively. Cellular adhesion, proliferation, osteogenesis-related genes, and alkaline phosphatase activity were evaluated. The results showed that peptides were successfully immobilized on Ti surface. Cell attachments on histatin-1 and mixed peptides coated groups are higher than control. Histatin-1 achieved the significantly highest cellular proliferation. Histatin-derived peptides improved the osteogenesis related-gene expression and alkaline phosphatase activity (p<0.05). This study suggested that histatin-1 immobilization by tresyl chloride-activation technique enhanced cellular responses and might be able to promote cellular activities around the dental implants.

Choline Acetyltransferase Induces the Functional Regeneration of the Salivary Gland in Aging SAMP1/Kl -/- Mice

Salivary gland dysfunction induces salivary flow reduction and a dry mouth, and commonly involves oral dysfunction, tooth structure deterioration, and infection through reduced salivation. This study aimed to investigate the impact of aging on the salivary gland by a metabolomics approach in an extensive aging mouse model, SAMP1/Klotho -/- mice. We found that the salivary secretion of SAMP1/Klotho -/- mice was dramatically decreased compared with that of SAMP1/Klotho WT (+/+) mice. Metabolomics profiling analysis showed that the level of acetylcholine was significantly decreased in SAMP1/Klotho -/- mice, although the corresponding levels of acetylcholine precursors, acetyl-CoA and choline, increased. Interestingly, the mRNA and protein expression of choline acetyltransferase (ChAT), which is responsible for catalyzing acetylcholine synthesis, was significantly decreased in SAMP1/Klotho -/- mice. The overexpression of ChAT induced the expression of salivary gland functional markers (α–amylase, ZO-1, and Aqua5) in primary cultured salivary gland cells from SAMP1/Klotho +/+ and -/- mice. In an in vivo study, adeno-associated virus (AAV)-ChAT transduction significantly increased saliva secretion compared with the control in SAMP1/Klotho -/- mice. These results suggest that the dysfunction in acetylcholine biosynthesis induced by ChAT reduction may cause impaired salivary gland function

Oral Candidiasis: A Disease of Opportunity

Oral candidiasis, commonly referred to as “thrush,” is an opportunistic fungal infection that commonly affects the oral mucosa. The main causative agent, Candida albicans, is a highly versatile commensal organism that is well adapted to its human host; however, changes in the host microenvironment can promote the transition from one of commensalism to pathogen. This transition is heavily reliant on an impressive repertoire of virulence factors, most notably cell surface adhesins, proteolytic enzymes, morphologic switching, and the development of drug resistance. In the oral cavity, the co-adhesion of C. albicans with bacteria is crucial for its persistence, and a wide range of synergistic interactions with various oral species were described to enhance colonization in the host. As a frequent colonizer of the oral mucosa, the host immune response in the oral cavity is oriented toward a more tolerogenic state and, therefore, local innate immune defenses play a central role in maintaining Candida in its commensal state. Specifically, in addition to preventing Candida adherence to epithelial cells, saliva is enriched with anti-candidal peptides, considered to be part of the host innate immunity. The T helper 17 (Th17)-type adaptive immune response is mainly involved in mucosal host defenses, controlling initial growth of Candida and inhibiting subsequent tissue invasion. Animal models, most notably the mouse model of oropharyngeal candidiasis and the rat model of denture stomatitis, are instrumental in our understanding of Candida virulence factors and the factors leading to host susceptibility to infections. Given the continuing rise in development of resistance to the limited number of traditional antifungal agents, novel therapeutic strategies are directed toward identifying bioactive compounds that target pathogenic mechanisms to prevent C. albicans transition from harmless commensal to pathogen.

Evaluation of the Antifungal and Wound-Healing Properties of a Novel Peptide-Based Bioadhesive Hydrogel Formulation

Oral candidiasis (OC) caused by the fungal pathogen Candida albicans is the most common opportunistic infection in immunocompromised populations. The dramatic increase in resistance to common antifungal agents has emphasized the importance of identifying alternative therapeutic options. Antimicrobial peptides have emerged as promising drug candidates due to their antimicrobial properties; specifically, histatin-5 (Hst-5), a peptide naturally produced and secreted by human salivary glands, has demonstrated potent activity against C. albicans However, as we previously demonstrated vulnerability for Hst-5 to proteolysis by C. albicans proteolytic enzymes at specific amino acid residues, a new variant (K11R-K17R) was designed with amino acid substitutions at the identified cleavage sites. The new resistant peptide demonstrated no cytotoxicity to erythrocytes or human oral keratinocytes. To evaluate the potential of the new peptide for clinical application, we utilized our FDA-approved polymer-based bioadhesive hydrogel as a delivery system and developed a therapeutic formulation specifically designed for oral topical application. The new formulation was demonstrated to be effective against C. albicans strains resistant to the traditional antifungals, and the in vitro therapeutic efficacy was found to be comparable to that of the common topical antifungal agents in clinical use. Importantly, in addition to its antifungal properties, our findings also demonstrated that the new peptide variant induces cell proliferation and rapid cell migration of human oral keratinocytes, indicative of wound healing properties. The findings from this study support the progression of the novel formulation as a therapeutic agent against oral candidiasis, as well as a therapeutic modality for promoting wound healing.

Effect of mechanically stimulated saliva on initial human dental biofilm formation

This study evaluated the impact of mechanically stimulated saliva on initial bacterial colonization. Interaction between oral bacteria and both unstimulated and stimulated saliva was examined in vitro by laying labeled bacteria over SDS-PAGE-separated salivary proteins. The effects of chewing on in vivo biofilm, microbial composition, and spatial arrangement were examined in two human volunteers using an intraoral stent containing retrievable enamel chips. In vitro experiments showed that bacterial binding to proteins from stimulated saliva was lower than that to proteins from unstimulated saliva. Lack of binding activity was noted with Streptococcus mutans and Lactobacillus casei. Human Oral Microbe Identification Microarray (HOMIM) analyses revealed a consistent chewing-related increase in the binding of Streptococcus anginosus and Streptococcus gordonii. Immunofluorescence microscopy demonstrated the presence of multi-species colonies and cells bearing different serotypes of the coaggregation-mediating streptococcal cell-surface receptor polysaccharides (RPS). Differences in bacterial colonization were noted between the two volunteers, while the type 4 RPS-reactive serotype was absent in one volunteer. Cells reacting with antibody against Rothia or Haemophilus were prominent in the early biofilm. While analysis of the data obtained demonstrated inter-individual variations in both in vitro and in vivo bacterial binding patterns, stimulating saliva with multiple orosensory stimuli may modulate oral bacterial colonization of tooth surfaces.

Salivary peptide histatin 1 mediated cell adhesion: a possible role in mesenchymal-epithelial transition and in pathologies

Histatins are histidine-rich peptides present in the saliva of humans and higher primates and have been implicated in the protection of the oral cavity. Histatin 1 is one of the most abundant histatins and recent reports show that it has a stimulating effect on cellular adherence, thereby suggesting a role in maintaining the quality of the epithelial barrier and stimulating mesenchymal-to-epithelial transition. Here we summarize these findings and discuss them in the context of previous reports. The recent findings also provide new insights in the physiological functions of histatin 1, which are discussed here. Furthermore, we put forward a possible role of histatin 1 in various pathologies and its potential function in clinical applications.

Histatins, wound healing, and cell migration

Wounds in the oral mucosa heal faster and more efficiently than those in the skin, although the mechanisms underlying these differences are not completely clear. In the last 10 years, a group of salivary peptides, the histatins, has gained attention on behalf of their ability to improve several phases of the wound-healing process. In addition to their roles as anti-microbial agents and in enamel maintenance, histatins elicit other biological effects, namely by promoting the migration of different cell types contained in the oral mucosa and in non-oral tissues. Histatins, and specifically histatin-1, promote cell adhesion and migration in oral keratinocytes, gingival and dermal fibroblasts, non-oral epithelial cells, and endothelial cells. This is particularly relevant, as histatin-1 promotes the re-epithelialization phase and the angiogenic responses by increasing epithelial and endothelial cell migration. Although the molecular mechanisms associated with histatin-dependent cell migration remain poorly understood, recent studies have pointed to the control of signaling endosomes and the balance of small GTPases. This review aimed to update the literature on the effects of histatins in cell migration, with a focus on wound healing. We will also discuss the consequences that this increasing field will have in disease and therapy design.

Salivary proteins and microbiota as biomarkers for early childhood caries risk assessment

Early childhood caries (ECC) is a term used to describe dental caries in children aged 6 years or younger. Oral streptococci, such as Streptococcus mutans and Streptococcus sorbrinus, are considered to be the main etiological agents of tooth decay in children. Other bacteria, such as Prevotella spp. and Lactobacillus spp., and fungus, that is, Candida albicans, are related to the development and progression of ECC. Biomolecules in saliva, mainly proteins, affect the survival of oral microorganisms by multiple innate defensive mechanisms, thus modulating the oral microflora. Therefore, the protein composition of saliva can be a sensitive indicator for dental health. Resistance or susceptibility to caries may be significantly correlated with alterations in salivary protein components. Some oral microorganisms and saliva proteins may serve as useful biomarkers in predicting the risk and prognosis of caries. Current research has generated abundant information that contributes to a better understanding of the roles of microorganisms and salivary proteins in ECC occurrence and prevention. This review summarizes the microorganisms that cause caries and tooth-protective salivary proteins with their potential as functional biomarkers for ECC risk assessment. The identification of biomarkers for children at high risk of ECC is not only critical for early diagnosis but also important for preventing and treating the disease.

Human salivary peptide histatin-1 stimulates epithelial and endothelial cell adhesion and barrier function

Histatins are multifunctional histidine-rich peptides secreted by the salivary glands and exclusively present in the saliva of higher primates, where they play a fundamental role in the protection of the oral cavity. Our previously published results demonstrated that histatin-1 (Hst1) promotes cell-substrate adhesion in various cell types and hinted that it could also be involved in cell-cell adhesion, a process of fundamental importance to epithelial and endothelial barriers. Here we explore the effects of Hst1 on cellular barrier function. We show that Hst1 improved endothelial barrier integrity, decreased its permeability for large molecules, and prevented translocation of bacteria across epithelial cell layers. These effects are mediated by the adherens junction protein E-cadherin (E-cad) and by the tight junction protein zonula occludens 1, as Hst1 increases the levels of zonula occludens 1 and of active E-cad. Hst1 may also promote epithelial differentiation as Hst1 induced transcription of the epithelial cell differentiation marker apolipoprotein A-IV (a downstream E-cad target). In addition, Hst1 counteracted the effects of epithelial-mesenchymal transition inducers on the outgrowth of oral cancer cell spheroids, suggesting that Hst1 affects processes that are implicated in cancer progression.-Van Dijk, I. A., Ferrando, M. L., van der Wijk, A.-E., Hoebe, R. A., Nazmi, K., de Jonge, W. J., Krawczyk, P. M., Bolscher, J. G. M., Veerman, E. C. I., Stap, J. Human salivary peptide histatin-1 stimulates epithelial and endothelial cell adhesion and barrier function.

Human Antimicrobial Peptides in Bodily Fluids: Current Knowledge and Therapeutic Perspectives in the Postantibiotic Era

Antimicrobial peptides (AMPs) are an integral part of the innate immune defense mechanism of many organisms. Due to the alarming increase of resistance to antimicrobial therapeutics, a growing interest in alternative antimicrobial agents has led to the exploitation of AMPs, both synthetic and isolated from natural sources. Thus, many peptide-based drugs have been the focus of increasing attention by many researchers not only in identifying novel AMPs, but in defining mechanisms of antimicrobial peptide activity as well. Herein, we review the available strategies for the identification of AMPs in human body fluids and their mechanism(s) of action. In addition, an overview of the distribution of AMPs across different human body fluids is provided, as well as its relation with microorganisms and infectious conditions.

Histatin 1 Enhances Cell Adhesion to Titanium in an Implant Integration Model

Cellular adhesion is essential for successful integration of dental implants. Rapid soft tissue integration is important to create a seal around the implant and prevent infections, which commonly cause implant failure and can result in bone loss. In addition, soft tissue management is important to obtain good dental aesthetics. We previously demonstrated that the salivary peptide histatin 1 (Hst1) causes a more than 2-fold increase in the ability of human adherent cells to attach and spread on a glass surface. Cells treated with Hst1 attached more rapidly and firmly to the substrate and to each other. In the current study, we examine the potential application of Hst1 for promotion of dental implant integration. Our results show that Hst1 enhances the attachment and spreading of soft tissue cell types (oral epithelial cells and fibroblasts) to titanium (Ti) and hydroxyapatite (HAP), biomaterials that have found wide applications as implant material in dentistry and orthopedics. For improved visualization of cell adhesion to Ti, we developed a novel technique that uses sputtering to deposit a thin, transparent layer of Ti onto glass slides. This approach allows detailed, high-resolution analysis of cell adherence to Ti in real time. Furthermore, our results suggest that Hst1 has no negative effects on cell survival. Given its natural occurrence in the oral cavity, Hst1 could be an attractive agent for clinical application. Importantly, even though Hst1 is specific for saliva of humans and higher primates, it stimulated the attachment and spreading of canine cells, paving the way for preclinical studies in canine models.

Immunocytochemical Localization of Histatins in Human Salivary Glands

Histatins are a family of salivary proteins with bactericidal and fungicidal activities that contribute to the innate defense of the oral cavity. Histatins are present in the serous granules of the parotid and submandibular glands. The important role of histatins in saliva, and the limited information on their cellular and subcellular distribution, prompted us to further define the localization of histatins in the major salivary glands. Immunogold-silver staining of 1-μm sections of plastic-embedded tissue with anti-histatin antibody revealed histatin immunoreactivity in the serous acinar cells of the parotid and submandibular glands, the serous demilune cells of the submandibular and sublingual glands, and in occasional intercalated duct cells. No reactivity was seen in mucous cells or in striated or excretory duct cells. Electron microscopic observations of thin sections labeled with anti-histatin and gold-labeled secondary antibodies revealed immunoreactivity associated with the rough endoplasmic reticulum and Golgi complex and in secretory granules of serous acinar and demilune cells. The granules of parotid acinar cells exhibited relatively uniform labeling of their content, whereas the granules of serous cells in the submandibular and sublingual glands showed variable labeling of the dense and light regions of their content. A few intercalated duct cells adjacent to the acinar cells also exhibited labeled granules. These results suggest that the serous cells of the major glands are the main source of histatins in human saliva. They are also consistent with several previous studies demonstrating the variable distribution of different proteins within the granule content.

Antimicrobial peptides in saliva of children with severe early childhood caries

OBJECTIVE

Controversies exist regarding the relationship between the concentrations of antimicrobial peptides (AMPs) and presence of dental caries in children. Thus, the aim of this study was to examine levels of AMPs in saliva of caries-free (CF), early childhood caries (ECC) and severe early childhood caries (S-ECC) children to determine if the levels of these salivary peptides individually or in combinations were related to caries severity and mutans streptococci levels.

DESIGN

36 to 60 month-old children were selected to participate in this study. Children were grouped into CF group (n=29), ECC group (n=25) and S-ECC group (n=29). Saliva was collected from children for microbiological analysis by culture. Salivary concentrations of cathelicidin LL-37, human β-defensin 2 (hBD-2), human β-defensin 3 (hBD-3) and histatin-5 (HTN-5) were determined by ELISA.

RESULTS

Salivary concentrations of AMPs did not differ among CF, ECC and S-ECC groups. Data showed positive correlations between mutans streptococci levels and salivary hBD-2 or HTN-5. Positive correlations were found between hBD-2, hBD-3, LL-37 and HTN-5. Combinations among AMPs, mainly LL-37, were positively associated with caries levels.

CONCLUSIONS

Salivary concentrations of AMPs individually were not associated with the severity of early childhood caries. The stimulus of caries appears to trigger a biological response, however, with a combination of these peptides.

Towards understanding oral health

During the last century, dental research has focused on unraveling the mechanisms behind various oral pathologies, while oral health was typically described as the mere absence of oral diseases. The term 'oral microbial homeostasis' is used to describe the capacity of the oral ecosystem to maintain microbial community stability in health. However, the oral ecosystem itself is not stable: throughout life an individual undergoes multiple physiological changes while progressing through infancy, childhood, adolescence, adulthood and old age. Recent discussions on the definition of general health have led to the proposal that health is the ability of the individual to adapt to physiological changes, a condition known as allostasis. In this paper the allostasis principle is applied to the oral ecosystem. The multidimensionality of the host factors contributing to allostasis in the oral cavity is illustrated with an example on changes occurring in puberty. The complex phenomenon of oral health and the processes that prevent the ecosystem from collapsing during allostatic changes in the entire body are far from being understood. As yet individual components (e.g. hard tissues, microbiome, saliva, host response) have been investigated, while only by consolidating these and assessing their multidimensional interactions should we be able to obtain a comprehensive understanding of the ecosystem, which in turn could serve to develop rational schemes to maintain health. Adapting such a 'system approach' comes with major practical challenges for the entire research field and will require vast resources and large-scale multidisciplinary collaborations.

How does it kill?: understanding the candidacidal mechanism of salivary histatin 5

Histatins are salivary cationic peptides that provide the first line of defense against oral candidiasis caused by Candida albicans. This minireview presents a critical evaluation of our knowledge of the candidacidal mechanism of histatin 5 (Hst 5). Hst 5 is the most potent among all histatin family members with regard to its antifungal activity. The mode of action of Hst 5 has been a subject of intense debate. Unlike other classical host innate immune proteins, pore formation or membrane lysis by Hst 5 has largely been disproven, and it is now known that all targets of Hst 5 are intracellular. Hst 5 binds C. albicans cell wall proteins (Ssa1/2) and glycans and is taken up by the cells through fungal polyamine transporters in an energy-dependent manner. Once inside the fungal cells, Hst 5 may affect mitochondrial functions and cause oxidative stress; however, the ultimate cause of cell death is by volume dysregulation and ion imbalance triggered by osmotic stress. Besides these diverse targets, a novel mechanism based on the metal binding abilities of Hst 5 is discussed. Finally, translational approaches for Hst 5, based on peptide design and synergy with other known drugs, are considered a step forward for bench-to-bed application of Hst 5.

Salivary and gingival crevicular fluid histatin in periodontal health and disease

Objectives: Histatin, with its anti bacterial, anti protease, and wound closure stimulating property might influence the pathogenesis of periodontal disease. This study assessed the presence of histatin in gingival crevicular fluid (GCF); the levels of salivary and GCF histatin in periodontal disease. Material and methods: It was a cross sectional study that included systemically healthy forty five subjects (22 males and 23 females) between the age group of 20 to 45 years. Based on Gingival Index (Loe and Silness ,1963) and Russell’s Periodontal Index they were grouped as 15 healthy (Group 1), 15 gingivitis (Group 2), and 15 periodontitis (Group 3) subjects. Whole pooled unstimulated saliva was collected by asking the patient to spit in a sterile container and GCF samples were collected using a micropipette from all the subjects. Histatin levels were assessed using Enzyme Linked Immunosorbent Assay (ELISA). The intergroup comparison was done by ANOVA and Mann Whitney U Test was done for pair wise comparison. Results: The results of this study show that histatin is present in saliva and gingival crevicular fluid. When the salivary histatin levels were compared it was found that the levels of histatin increase from health to periodontitis but the levels of histatin in the gingival crevicular fluid and saliva had no correlation with severity of periodontal disease as there was no statistically significant difference between the three groups. Conclusions: It can be concluded that histatin cannot be used as a potential marker of periodontal disease.

Key words:Periodontal disease, histatin, gingival crevicular fluid, saliva, gingival index, periodontal index, enzyme linked immunosorbent assay.

Impaired Histatin-5 Levels and Salivary Antimicrobial Activity against C. albicans in HIV Infected Individuals

HIV-infected individuals constitute a population highly susceptible to opportunistic infections, particularly oral candidiasis caused by the most pathogenic human fungal species Candida albicans. Host-produced salivary antimicrobial peptides are considered to be an important part of the host innate immune system involved in protection of the oral cavity against colonization and infection by microbial species. Histatin-5 (Hst-5) specifically has exhibited potent anti-candidal properties in vitro. However, its importance in protecting the oral mucosa against candidal colonization and importantly, its contribution to the observed enhanced susceptibility of HIV-infected individuals to candidiasis has not been previously investigated. To that end, a novel immunoassay was used to demonstrate significant decrease in salivary Hst-5 levels in HIV+ individuals concomitant with enhanced candidal prevalence. Further, saliva's anti-candidal potency was found to be proportional to Hst-5 concentration and significantly compromised in HIV+ subjects compared to controls. The key role for Hst-5 was further confirmed upon exposure to the Hst-5-specific antibody where saliva's initial killing activity was substantially compromised. Combined, these findings identify Hst-5 as a key anti-candidal salivary component and demonstrate its decreased levels in HIV infection providing new insights into oral Innate immune defense mechanisms and the enhanced susceptibility of HIV+ individuals to oral candidiasis.

One decade of salivary proteomics: current approaches and outstanding challenges

Efforts have been made in the last decade towards the complete characterization of saliva proteome using gel-based and gel-free approaches. The combination of these strategies resulted in the increment of the dynamic range of saliva proteome, which yield in the identification of more than 3,000 different protein species. Comparative protein profiling using isotope labeling and label free approaches has been used for the identification of novel biomarkers for oral and related diseases. Although progresses have been made in saliva proteome characterization, the comparative profiling in different pathophysiological conditions is still at the beginning if compared to other bodily fluids. The potential biomarkers identified so far lack specificity once common differentially expressed proteins were detected in the saliva of patients with distinct diseases. In addition, recent research works focused on saliva peptidome profiling already allowed a better understanding of peptides' physiological role in oral cavity. This review provides an overview of the major achievements in saliva proteomics giving emphasis to methodological concerns related with saliva collection, treatment and analysis, as well as the main advantages and pitfalls underlying salivary proteomic strategies and potential clinical outcomes.

Salivary defense proteins: their network and role in innate and acquired oral immunity

There are numerous defense proteins present in the saliva. Although some of these molecules are present in rather low concentrations, their effects are additive and/or synergistic, resulting in an efficient molecular defense network of the oral cavity. Moreover, local concentrations of these proteins near the mucosal surfaces (mucosal transudate), periodontal sulcus (gingival crevicular fluid) and oral wounds and ulcers (transudate) may be much greater, and in many cases reinforced by immune and/or inflammatory reactions of the oral mucosa. Some defense proteins, like salivary immunoglobulins and salivary chaperokine HSP70/HSPAs (70 kDa heat shock proteins), are involved in both innate and acquired immunity. Cationic peptides and other defense proteins like lysozyme, bactericidal/permeability increasing protein (BPI), BPI-like proteins, PLUNC (palate lung and nasal epithelial clone) proteins, salivary amylase, cystatins, prolin-rich proteins, mucins, peroxidases, statherin and others are primarily responsible for innate immunity. In this paper, this complex system and function of the salivary defense proteins will be reviewed.

Compositional modification of nascent in vitro dental plaques by human host-defence peptides

Salivary host-defence peptides include defensins, histatins and cathelicidin. We have investigated the effects of these peptides on the microbial composition of dental plaques. Salivary consortia, established within hydroxyapatite disc models, were exposed during development to physiological levels of human neutrophil proteins (HNP) 1 and 2; human β defensins (hβD) 1, 2 and 3; histatins (His) 5 and 8; and cathelicidin (LL37). Effects on aggregation and microbial composition were determined using fluorescence microscopy; and differential culture with PCR-DGGE, respectively. LIVE/DEAD microscopic analysis indicated that HDPs decreased total bacterial viability, whilst β defensins, paired HNPs, His 5, His 8 and the HDPs combined inhibited bacterial aggregation. According to differential culture, all test HDPs (except His 5) significantly decreased the abundance of Gram-negative anaerobes and lactobacilli (except HNP 2, hβD 1, paired HNPs and His 5). Combined HNPs and paired hβD 1 and 3 inhibited streptococci, whereas HNP 1, hβD 1, hβD 3, His 5 and LL37 increased streptococcal numbers. According to cluster analyses of DGGE profiles, HDP-exposed plaques were compositionally distinct from undosed controls. Thus, whilst HDPs reportedly exhibit variable potency against oral bacteria in endpoint susceptibly tests, exposure of nascent plaques can markedly influence bacterial viability, composition and microbial aggregation.

Antimicrobial peptides and periodontal disease

AIMS

The goal of this review is to identify the antimicrobial proteins in the oral fluids, saliva and gingival crevicular fluid and identify functional families and candidates for antibacterial treatment.

RESULTS

Periodontal biofilms initiate a cascade of inflammatory and immune processes that lead to the destruction of gingival tissues and ultimately alveolar bone loss and tooth loss. Treatment of periodontal disease with conventional antibiotics does not appear to be effective in the absence of mechanical debridement. An alternative treatment may be found in antimicrobial peptides and proteins, which can be bactericidal and anti-inflammatory and block the inflammatory effects of bacterial toxins. The peptides have co-evolved with oral bacteria, which have not developed significant peptide resistance. Over 45 antibacterial proteins are found in human saliva and gingival crevicular fluid. The proteins and peptides belong to several different functional families and offer broad protection from invading microbes. Several antimicrobial peptides and proteins (AMPs) serve as templates for the development of therapeutic peptides and peptide mimetics, although to date none have demonstrated efficacy in human trials.

CONCLUSIONS

Existing and newly identified AMPs may be developed for therapeutic use in periodontal disease or can serve as templates for peptide and peptide mimetics with improved therapeutic indices.

Histatins: antimicrobial peptides with therapeutic potential

Histatins are a group of antimicrobial peptides, found in the saliva of man and some higher primates, which possess antifungal properties. Histatins bind to a receptor on the fungal cell membrane and enter the cytoplasm where they target the mitochondrion. They induce the non-lytic loss of ATP from actively respiring cells, which can induce cell death. In addition, they have been shown to disrupt the cell cycle and lead to the generation of reactive oxygen species. Their mode of action is distinct from those exhibited by the conventional azole and polyene drugs, hence histatins may have applications in controlling drug-resistant fungal infections. The possibility of utilising histatins for the control of fungal infections of the oral cavity is being actively pursued with the antifungal properties of topical histatin preparations and histatin-impregnated denture acrylic being evaluated. Initial clinical studies are encouraging, having demonstrated the safety and efficacy of histatin preparations in blocking the adherence of the yeast Candida albicans to denture acrylic, retarding plaque formation and reducing the severity of gingivitis. Histatins may represent a new generation of antimicrobial compounds for the treatment of oral fungal infections and have the advantage, compared with conventional antifungal agents, of being a normal component of human saliva with no apparent adverse effects on host tissues and having a mode of action distinct to azole and polyene antifungals.

Antimicrobial peptide inhibition of Porphyromonas gingivalis 381-induced hemagglutination is improved with a synthetic decapeptide

The effects of various antimicrobial peptides (AMPs) on disrupting the hemagglutinating ability of cellular components of the putative oral pathogen Porphyromonas gingivalis were examined. AMP inhibition of P. gingivalis 381-induced hemagglutination using vesicles (VES) or outer membrane (OM) preparations was determined within standardized hemagglutination assays using various mammalian erythrocytes. A synthetic decapeptide (KSL-W) and its truncated peptide analogs were evaluated and compared with selected classes of AMPs derived from naturally occurring innate defense peptides. All tested AMPs were effective in disrupting P. gingivalis-induced hemagglutination among tested erythrocytes, with the exception of magainin I and the truncated KSL-W analogs. LL-37 was generally the most potent followed by histatin 5. The synthetic decapeptide (KSL-W) was found to be similar to the histatin 8 peptide in terms of inhibitory effect. In addition, co-application assays (with selected oral-related AMPs+/-KSL-W) were employed to determine if co-application procedures would improve hemagglutination abrogation above that of oral-related AMPs alone. These experiments revealed that the KSL-W peptide improved hemagglutination inhibition above that of each of the oral-related peptides (histatin 5 and 8, LL-37) alone. Among mammalian erythrocytes, significant peptide-induced hemagglutination was observed for the cathelicidin class AMPs, LL-37 and indolicidin (>or=25 and >or=100 microM respectively). In contrast, KSL-W did not induce erythrocyte agglutination throughout any concentration range tested (0.1-1000 microM). Our results suggest that several AMPs are effective in disrupting P. gingivalis 381-induced hemagglutination and that the co-application of a small, synthetically derived peptide may serve to augment the role of local host AMPs engaged in innate defense.

Histatins Enhance Wound Closure with Oral and Non-oral Cells

The role of human saliva in oral wound-healing has never been fully elucidated. We previously demonstrated that parotid-salivary histatins enhance in vitro wound closure. The question remains whether other salivary-gland secretions enhance wound closure, and also the effects of histatins on primary and non-oral cells. Since the presence of histatins is not limited to parotid saliva, we expected to observe wound-closure activity of other salivary-gland secretions. However, here we show that non-parotid saliva does not stimulate wound closure, most probably due to the presence of mucins, since the addition of MUC5B to parotid saliva abolished its effect. Furthermore, we found that histatins stimulated wound closure of (primary) cells of both oral and non-oral origin. This suggests that the cellular receptor of histatins is widely expressed and not confined to cells derived from the oral cavity. These findings encourage the future therapeutic application of histatins in the treatment of all kinds of wounds.

Interaction of age and specific saliva component output on caries

BACKGROUND AND AIMS

The purpose of this study was to explore the relationship between individual salivary components, dental caries and age, utilizing the data from the Oral Health: San Antonio Longitudinal Study of Aging (OH:SALSA).

METHODS

The study population comprised a well-defined stratified sample of 811 dentate men and women. Subjects were divided into four age groups from 35 to 75+ years old. Unstimulated and stimulated submandibular/sublingual saliva flow rates, unstimulated and stimulated parotid saliva flow rates, total protein, 6 individual proteins and 4 inorganic constituents were measured. Specific salivary components were lactoferrin, secretory IgA, albumin, lysozyme, mucin, cystatin, K+, Ca2+, Na+ and Cl-. Caries measurements were the DMFT Index for crowns and for roots, Tooth Health Index for crowns and roots, Tooth caries, Root caries and Tooth restoration. The data on saliva components were square root transformed for linearity prior to analysis. Analysis was carried out in two stages. Partial correlation was performed, in order to identify significant relationships between specific salivary components and caries measurements, controlling for age group. In the second stage, using caries measurement as the dependant variable, the effects of age, flow rate and specific salivary component output (product of flow rate and concentration) were examined.

RESULTS

Significant associations were found between caries, age and specific individual submandibular/sublingual salivary proteins (lactoferrin, albumin, lysozyme, mucin and cystatin) and specific inorganic constituents (K+, Ca2+, Na+ and Cl-).

CONCLUSIONS

Changes in submandibular/ sublingual salivary component output during aging are correlated with high caries prevalence. These changes in saliva components over age may represent caries risk indicators.

Candida glabrata: an emerging oral opportunistic pathogen

Following the widespread use of immunosuppressive therapy and broad-spectrum antimycotic prophylaxis, C. glabrata has emerged as an important opportunistic pathogen in the oral mucosa. In the past, studies on the virulence factors and host-pathogen interactions of this organism were scarce, but continued to rise in recent years. Denture-wearing, immunosuppression, antibiotic therapy, and aging are risk factors for oral colonization or infection with C. glabrata. Compared with C. albicans, C. glabrata exhibits lower oral keratinocyte-adherence capacity, but higher denture-surface-adherence ability. The role of extracellular hydrolase production in the virulence of this organism does not appear to be as important as it is in C. albicans pathogenesis. Although traditionally thought of as a non-transforming yeast organism, both phenotypic switching and pseudohyphal formation have recently been identified in C. glabrata, but their role in pathogenesis is not known. With the exception of granulocyte monocyte colony-stimulating factor, C. glabrata triggers a lower proinflammatory cytokine response in oral epithelial cells than does C. albicans, in a strain-dependent manner. C. glabrata is less susceptible to killing by human beta-defensins than is C. albicans and exhibits various degrees of resistance to the antifungal activity of salivary histatins and mucins. In addition, C. glabrata possesses both innate and acquired resistance against antifungal drugs, due to its ability to modify ergosterol biosynthesis, mitochondrial function, or antifungal efflux. This resistance allows for its relative overgrowth over other susceptible species and may contribute to the recent emergence of C. glabrata infections in chronically immunocompromised populations. Further investigations on the virulence and host-pathogen interactions of C. glabrata are needed to better define the pathogenesis of oral C. glabrata infection in susceptible hosts.

Salivary proteome and its genetic polymorphisms

Salivary diagnostics for oral as well as systemic diseases is dependent on the identification of biomolecules reflecting a characteristic change in presence, absence, composition, or structure of saliva components found under healthy conditions. Most of the biomarkers suitable for diagnostics comprise proteins and peptides. The usefulness of salivary proteins for diagnostics requires the recognition of typical features, which make saliva as a body fluid unique. Salivary secretions reflect a degree of redundancy displayed by extensive polymorphisms forming families for each of the major salivary proteins. The structural differences among these polymorphic isoforms range from distinct to subtle, which may in some cases not even affect the mass of different family members. To facilitate the use of modern state-of-the-art proteomics and the development of nanotechnology-based analytical approaches in the field of diagnostics, the salient features of the major salivary protein families are reviewed at the molecular level. Knowledge of the structure and function of salivary gland-derived proteins/peptides has a critical impact on the rapid and correct identification of biomarkers, whether they originate from exocrine or non-exocrine sources.

Analysis of the human saliva proteome

Interest in the characterization of the salivary proteome has increased in the last few years. This review discusses the different techniques and methodologies applied to the separation and identification of salivary proteins. Nowadays, proteomic techniques are the state of the art for the analysis of biologic materials and saliva is no exception. 2D electrophoresis and tryptic digest analysis by mass spectrometry are the typical methodology, but new approaches using 2D liquid chromatography/mass spectrometry methods have already been introduced for saliva analysis. Due to their important physiologic role in the oral cavity, low-molecular-weight proteins and peptides are also included in this article and the methodologies discussed.

Oral fluid proteolytic effects on histatin 5 structure and function

Histatins are human salivary antifungal proteins that are prone to extensive enzymatic degradation upon their release into the oral cavity. Histatin proteolysis, leading to the disappearance of the intact protein can be expected to have functional consequences. Histatin 5, comprising 24 residues, is the smallest of the major salivary histatins and the most active in terms of its antifungal properties. The rate and mode of histatin 5 degradation were determined by incubating the protein in whole saliva supernatant for various time intervals. Fragmentation products were collected by reversed-phase high performance liquid chromatography (RP-HPLC), characterised structurally by matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) mass spectrometry and functionally in a fungal growth inhibition assay. Of the 19 fragments identified, 16 were derived from single proteolytic cleavage events in histatin 5. A remarkable finding was the inter-subject consistency in the histatin 5 degradation pattern. Added histatin 5 disappeared from whole saliva supernatant at an average rate of 105+/-22 microg/ml/h, which in part could explain the virtual absence of histatin 5 in whole saliva. Despite the rapid proteolysis of histatin 5, the early degradation mixture was as active in antifungal assays as intact histatin 5. These data demonstrate that the oral-fluid mediated proteolysis of histatin 5 represents an intrinsic biological property of whole saliva. The data also reveal that the early proteolysis phase of histatin 5 does not abolish the antifungal properties associated with this protein.

Statherin and Histatin 1 Reduce Parotid Saliva-Promoted Streptococcus mutans Strain MT8148 Adhesion to Hydroxyapatite Surfaces

Small salivary phosphoproteins--statherin (ST) and histatin 1 (HT1) - are found in the acquired enamel pellicle which modulates Streptococcus mutans adhesion onto dental enamel. However, their roles in S. mutans adhesion onto enamel surfaces are still undefined. The aim of this study was to investigate whether and how ST and HT1 affect (i) S. mutans adhesion and (ii) the adsorption of S. mutans adhesion-promoting salivary proteins onto hydroxyapatite (HA) in vitro. We fractionated human parotid saliva by adsorption to HA and further by gel filtration chromatography. Adhesion of [3H]-labeled S. mutans strain MT8148 onto sintered HA plates was promoted significantly (>10-fold) by high-molecular weight glycoprotein fraction (HMWGP), but not by purified ST or HT1. More interestingly, promotion of S. mutans adhesion onto HA by HMWGP was significantly reduced by adding purified ST or HT1 to HMWGP. [3H]-labeled S. mutans adhesion on HA was positively correlated to the [14C]-labeled HMWGP adsorption onto HA, which was also reduced by the addition of purified ST and HT1. Synthetic peptides corresponding to ST and HT1 reduced the parotid saliva-promoted S. mutans adhesion. However, removal of the negative charges in the N-terminal domains of ST and HT1 diminished their inhibitory effects on S. mutans adhesion promoted by parotid saliva. We conclude that ST and HT1 competitively inhibit the adsorption of salivary HMWGP, and thereby reduce S. mutans adhesion onto HA surfaces.

The oral microflora — friend or foe? Can we decide?

This paper discusses the factors that determine whether the oral microflora play a beneficial or detrimental role in the health of an individual during their life. The resident microflora of the mouth is diverse, and distinct from that found elsewhere in the body due to its unique biological and physical properties. This natural microflora is essential for the normal development of the physiology of the host, and contributes to the host defences by excluding exogenous micro-organisms. The oral microflora varies in composition on distinct surfaces (e.g. teeth, mucosa), and at sites on a specific surface (e.g. fissures, gingival crevice), demonstrating that subtle properties of a habitat influence the ability of individual species to colonise and dominate. The composition of these oral microbial communities remains relatively stable over time (microbial homeostasis). This stability does not indicate a passive relationship with the host, but reflects a dynamic balance among the component species. However, this stability can be perturbed by significant changes to the oral environment or in a person's life-style that occur during the life of an individual. Alterations in diet, medication, smoking, saliva flow, denture wearing, general health, etc, can lead to overgrowth by previously minor components of the oral microflora, which can predispose a site to disease. Likewise, the immune response can wane in old age, which may result in colonisation by exogenous and often pathogenic micro-organisms. Oral micro-organisms can also act as opportunistic pathogens, and cause serious disease elsewhere in the body. Therefore, active oral health care management is needed in order to maintain microbial homeostasis throughout life to ensure that we reap the benefits of our resident oral bacteria and not suffer from their mischief.

Salivary histatins in human deep posterior lingual glands (of von Ebner)

OBJECTIVE

Human saliva contains a family of low molecular weight histidine-rich proteins, named histatins, characterised by bactericidal and fungicidal activities in vitro against several microbial pathogens, such as Streptococcus mutans and Candida albicans. They represent a major component of an innate host non-immune defense system. In an earlier study we described the distribution of histatins in the glandular parenchyma of human major salivary glands, confirming that all human major salivary glands are involved in the secretion of histatins into saliva. In the present study we determined the expression and localisation of histatins in human posterior deep lingual glands (von Ebner's glands) by means of immunoelectron microscopy.

DESIGN

Thin sections of normal human salivary glands, embedded in Epon resin, were incubated with rabbit polyclonal antibodies specific for human histatins and successively with a gold conjugated goat anti-rabbit IgG used as secondary antibody. Sections incubated with medium devoid of primary antibody or containing non-immune serum were used as controls.

RESULTS

The serous secreting cells represented the main source of histatins in the glandular parenchyma of von Ebner's glands. At the electron microscopic level, labeling was associated with rough endoplasmic reticulum, Golgi complex and secretory granules that represented the main cytoplasmic site of histatin localisation. However, variability in the intensity of labeling was observed among adjacent cells.

CONCLUSIONS

The present results show for the first time that human von Ebner's glands produce and represent a significant source of histatins, supporting the hypothesis of their important role in preventing microbial assaults on the tissues in the posterior region of the tongue and in the circumvallate papillae.

Oral health measurement in nursing research: state of the science

Oral health can impact general health and systemic disease. Changes in dental plaque, oral microbial flora, and local oral immunity may be important in the development or exacerbation of disease in critically ill patients, trauma patients, adults with chronic obstructive pulmonary disease, and frail elderly. Inasmuch as oral health potentially can be influenced by nursing interventions, nursing research in this area can contribute greatly to improved patient outcomes in these diverse populations. The authors' research teams have conducted several federally funded projects focused on oral health and have developed synergy in research methods. A unifying theme for these research projects is the measurement of oral health. Standardized measures of components of oral health are available and applicable across populations, and their uses and relationship to nursing research and patient outcomes will be discussed.

Association of candidal activity with denture use and salivary flow in symptom-free adults over 60 years1

The purpose of this study was to examine the amount of palatal mucosa Candida species associated with denture use and stimulated salivary flow in symptom-free adults over 60 years. The subjects were 351 (189 men and 162 women) independently living elderly people with a mean age of 66.7 +/- 4.3 (SD) years. Candidal activity of palatal mucosa was evaluated by the pH change in the medium that was associated with the acid production of the yeast. Subjects whose stimulated salivary flow rate was less than 0.5 ml/min were placed in the hyposalivation group. A multiple logistic regression analysis was used to determine if an independent variable was statistically significant after controlling for other variables. Candidal activity of the palatal mucosa was significantly associated with the dental status of the maxillae (Kruskal-Wallis test, P < 0.001), but was not significantly associated with age or drug intake. In maxillary denture wearers, Candidal activity of palatal mucosa had a significantly positive correlation with candidal activity of tissue fitting surfaces of maxillary dentures (r = 0.806, P < 0.001). A multiple logistic regression analysis showed that high candidal activity of the palate was significantly associated with being male and wearing maxillary removable dentures. Stimulated salivary flow rate was likely to be negatively related to high candidal activity (P = 0.07). This study suggests that the activity of Candida species in the oral cavity is associated with the wearing of removable dentures and stimulated salivary flow, independent of age or gender even in the relatively healthy elderly.