Hyposalivation and 10-year all-cause mortality in an elderly Japanese population

Evaluation and management of dry mouth and its complications in rheumatology practice

INTRODUCTION

The symptom of dry mouth has multiple potential etiologies and can be a diagnostic clue to the presence of common systemic diseases encountered in rheumatology practice. The presence of decreased saliva flow (i.e. salivary hypofunction) defines a subset of dry mouth patients in whom there may be reversible drug effects, an iatrogenic insult such as head and neck irradiation, or a disease that directly involves the salivary glands (e.g. Sjögren's disease). The assessment of salivary hypofunction includes sialometry, salivary gland imaging, salivary gland biopsy, and an assessment for relevant systemic diseases. Optimal management of dry mouth requires accurate definition of its cause, followed by general measures that serve to alleviate its symptoms and prevent its complications.

AREAS COVERED

Through a literature search on xerostomia and salivary hypofunction, we provide an overview of the causes of dry mouth, highlight the potential impact of salivary hypofunction on oral and systemic health, detail routine evaluation methods and treatment strategies, and emphasize the importance of collaboration with oral health care providers.

EXPERT OPINION

Our Expert Opinion is provided on unmet needs in the management of dry mouth and relevant research progress in the field.

The role and mechanism of tight junctions in the regulation of salivary gland secretion

Tight junctions (TJs) are cell-cell interactions that localize at the most apical portion of epithelial/endothelial cells. One of the predominant functions of TJs is to regulate material transport through paracellular pathway, which serves as a selective barrier. In recent years, the expression and function of TJs in salivary glands has attracted great interest. The characteristics of multiple salivary gland TJ proteins have been identified. During salivation, the activation of muscarinic acetylcholine receptor and transient receptor potential vanilloid subtype 1, as well as other stimuli, promote the opening of acinar TJs by inducing internalization of TJs, thereby contributing to increased paracellular permeability. Besides, endothelial TJs are also redistributed with leakage of blood vessels in cholinergic-stimulated submandibular glands. Furthermore, under pathological conditions, such as Sjögren's syndrome, diabetes mellitus, immunoglobulin G4-related sialadenitis, and autotransplantation, the integrity and barrier function of TJ complex are impaired and may contribute to hyposalivation. Moreover, in submandibular glands of Sjögren's syndrome mouse model and patients, the endothelial barrier is disrupted and involved in hyposecretion and lymphocytic infiltration. These findings enrich our understanding of the secretory mechanisms that link the importance of epithelial and endothelial TJ functions to salivation under both physiological and pathophysiological conditions.

World Workshop on Oral Medicine VIII: Development of a Core Outcome Set for Dry Mouth: A Systematic Review of Outcome Domains for Xerostomia

OBJECTIVE

The purpose of this study was to identify all outcome domains used in clinical studies of xerostomia, that is, subjective sensation of dry mouth. This study is part of the extended project "World Workshop on Oral Medicine Outcomes Initiative for the Direction of Research" to develop a core outcome set for dry mouth.

STUDY DESIGN

A systematic review was performed on MEDLINE, EMBASE, CINAHL, and Cochrane Central Register of Controlled Trials databases. All clinical and observational studies that assessed xerostomia in human participants from 2001 to 2021 were included. Information on outcome domains was extracted and mapped to the Core Outcome Measures in Effectiveness Trials taxonomy. Corresponding outcome measures were summarized.

RESULTS

From a total of 34,922 records retrieved, 688 articles involving 122,151 persons with xerostomia were included. There were 16 unique outcome domains and 166 outcome measures extracted. None of these domains or measures were consistently used across all the studies. The severity of xerostomia and physical functioning were the 2 most frequently assessed domains.

CONCLUSION

There is considerable heterogeneity in outcome domains and measures reported in clinical studies of xerostomia. This highlights the need for harmonization of dry mouth assessment to enhance comparability across studies and facilitate the synthesis of robust evidence for managing patients with xerostomia.

Large Contribution of Oral Status for Death Among Modifiable Risk Factors in Older Adults: The Japan Gerontological Evaluation Study (JAGES) Prospective Cohort Study

BACKGROUND

Oral diseases are preventable and modifiable, but highly prevalent, and cause worse oral status. Particularly, tooth loss has increased in aging societies. However, studies on population-attributable risks of modifiable risk factors for mortality have neglected oral status. This study aimed to investigate the impact of modifiable risk factors on mortality, including oral status.

METHODS

This cohort study used the Japan Gerontological Evaluation Study data, including participants aged ≥65 years. The outcome was death between August 2010 and March 2017. We calculated the hazard ratios (HRs) and population attributable fraction (PAF) of modifiable risk factors (oral status, hypertension, depression, heart disease, diabetes, physical activity, smoking status, and alcohol drinking history) for mortality.

RESULTS

Analyses included 24 175 men and 27 888 women (mean age: 73.8 [6.0] and 74.2 [6.1], respectively). In men, after adjusting for covariates, having no teeth showed the highest hazard ratio (HR = 1.67, 95% confidence interval [CI] = 1.51-1.86) among the modifiable risk factors, and the PAF for the number of teeth (18.2%) was the second largest following age. In women, having no teeth had the third largest HR (HR = 1.37, 95% CI = 1.19-1.56) following current and former smoking. The PAF for the number of teeth (8.5%) was the sixth largest, which was larger than that of smoking status (4.8%).

CONCLUSIONS

In the older population, the HR and PAF of the number of teeth on mortality were sufficiently large compared with other modifiable risk factors, especially in men. Therefore, maintaining good oral status should be included more in global health policies.

Altered Rheological Properties of Saliva with Aging in Mouse Sublingual Gland

Mucin in saliva plays a critical role in the hydration and lubrication of the oral mucosa by retaining water molecules, and its impaired function may be associated with hyposalivation-independent xerostomia. Age-dependent effects on salivary gland function and rheological properties of secreted saliva are not fully understood as aging is a complex and multifactorial process. We aimed to evaluate age-related changes in the rheological properties of saliva and elucidate the underlying mechanism. We performed ex vivo submandibular gland (SMG) and sublingual gland (SLG) perfusion experiments to collect saliva from isolated glands of young (12 wk old) and aged (27 mo old) female C57BL/6J mice and investigate the rheological properties by determining the spinnbarkeit (viscoelasticity). While fluid secretion was comparable in SMG and SLG of both mice, spinnbarkeit showed a significant decrease in SLG saliva of aged mice than that of young mice. There were no significant differences in GalNAc concentration between young and aged SLG saliva. Liquid chromatography/tandem mass spectrometry analysis of SLG saliva revealed that (Hex)₁ (HexNAc)₁ (NeuAc)₁ at m/z 793.31 was the most abundant O-glycan structure in SLG saliva commonly detected in both mice. Lectin staining of salivary gland tissue showed that SLG stained strongly with Maackia amurensis lectin II (MAL II) while Sambucus nigra agglutinin (SNA) stained little, if any, SLG. The messenger RNA expression of St3gal1 that encodes an α-2,3 sialic acid sialyltransferase SIAT4-A showed a decrease in SLG of aged mice, confirmed by a Western blot analysis. Lectin blot analysis in SLG saliva revealed that the relative signal intensity detected by MAL II was significantly lower in aged SLG. Our results suggest that spinnbarkeit decreases in SLG of aging mice due to downregulation of sialic acid linked to α-2,3 sialic acid sialyltransferase expression.

A Review on Xerostomia and Its Various Management Strategies: The Role of Advanced Polymeric Materials in the Treatment Approaches

The medical term xerostomia refers to the subjective sensation of oral dryness. The etiology seems to be multifactorial with the most frequently reported causes being the use of xerostomic medications, neck and head radiation, and systematic diseases (such as Sjögren’s syndrome). Xerostomia is associated with an increased incidence of dental caries, oral fungal infections, and difficulties in speaking and chewing/swallowing, which ultimately affect the oral health-related quality of life. The development of successful management schemes is regarded as a highly challenging project due to the complexity of saliva. This is why, in spite of the fact that there are therapeutic options aiming to improve salivary function, most management approaches are alleviation-oriented. In any case, polymers are an integral part of the various formulations used in every current treatment approach, especially in the saliva substitutes, due to their function as thickening and lubricating agents or, in the case of mucoadhesive polymers, their ability to prolong the treatment effect. In this context, the present review aims to scrutinize the literature and presents an overview of the role of various polymers (or copolymers) on either already commercially available formulations or novel drug delivery systems currently under research and development.

Association between dry mouth and physical frailty among community-dwelling older adults in Japan: The Otassha Study

OBJECTIVE

To elucidate the relationship between physical frailty and dry mouth among community-dwelling older adults in Japan.

BACKGROUND

Oral hypofunction is associated with physical frailty in older adults. Dry mouth, subjectively evaluated as xerostomia and objectively measured as hyposalivation, is highly prevalent in older adults. However, few reports have used both measures of dry mouth and investigated their association with physical frailty.

MATERIALS AND METHODS

This cross-sectional study included 643 individuals (mean age, 73.9 years) from the Otassha Study in 2019. Xerostomia was assessed using the 5-item Summated Xerostomia Inventory (SXI). Hyposalivation was assessed by measuring the amount of resting saliva using the modified cotton roll method. Frailty phenotypes were defined by weakness, slowness, weight loss, low physical activity level and exhaustion components, and served as the outcome variable. Participants with three or more components were considered physically frail, and those with one or two components were considered pre-frail. Ordinal logistic regression analyses were performed to evaluate the associations between physical frailty and xerostomia and hyposalivation.

RESULTS

Among the participants, 4.5% and 49.8% had physical frailty and pre-frailty, respectively. In ordinal logistic regression analysis adjusted for demographic and health characteristics, the SXI score was associated with physical frailty status (adjusted odds ratio for a one-point increase in SXI, 1.12; 95% confidence interval, 1.06-1.19). However, no difference was observed between the amount of resting saliva and severity of physical frailty.

CONCLUSION

Xerostomia is associated with physical frailty among community-dwelling older adults in Japan.

CLINICAL TRIAL REGISTRATION

Not applicable.

Oral health and all-cause, cardiovascular disease, and respiratory mortality in older people in the UK and USA

Preventing deterioration of oral health in older age can be crucial for survival. We aimed to examine associations of oral health problems with all-cause, cardiovascular disease (CVD), and respiratory mortality in older people. We used cohort data from the British Regional Health Study (BRHS) (N = 2147, 71-92 years), and the Health, Aging and Body Composition (HABC) Study (USA) (N = 3075, 71-80 years). Follow-up was 9 years (BRHS) and 15 years (HABC Study). Oral health comprised tooth loss, periodontal disease, dry mouth, and self-rated oral health. Cox regression was performed for all-cause mortality, competing risks for CVD mortality, and accelerated failure time models for respiratory mortality. In the BRHS, tooth loss was associated with all-cause mortality (hazard ratio (HR) = 1.59, 95% CI 1.09, 2.31). In the HABC Study, tooth loss, dry mouth, and having ≥ 3 oral problems were associated with all-cause mortality; periodontal disease was associated with increased CVD mortality (subdistribution hazard ratio (SHR) = 1.49, 95% CI 1.01, 2.20); tooth loss, and accumulation of oral problems were associated with high respiratory mortality (tooth loss, time ratio (TR) = 0.73, 95% CI 0.54, 0.98). Findings suggest that poor oral health is associated with mortality. Results highlight the importance of improving oral health to lengthen survival in older age.

Therapeutic Recommendations for the Management of Older Adult Patients with Sjögren's Syndrome

Primary Sjögren's syndrome (SjS) is a systemic autoimmune disease most commonly diagnosed in middle-aged women. Although the disease can occur at all ages, it is diagnosed between 30 and 60 years of age in two-thirds of patients. In more than 20% of cases, the people are older than 65 years. In this review, we focus on the therapeutic management of primary SjS in older patients, following the recently published 2020 European League Against Rheumatism (EULAR) recommendations for the management of the disease with topical and systemic therapies. These recommendations are applicable to all patients with primary SjS regardless of age at diagnosis, although the therapeutic management in older patients requires additional considerations. Older patients are more likely to have pulmonary, liver, kidney, or heart-related comorbidities (even cognitive disturbances); caution is required when most drugs are used, including muscarinic agents, systemic corticosteroids and synthetic immunosuppressants. It is also important to monitor the use of eye drops containing steroids due to the increased risk of developing cataracts, a frequent ocular complication in the older population. In contrast, the majority of drugs that can be used topically (pilocarpine rinses, eye drops containing topical non-steroidal anti-inflammatory drugs (NSAIDs) or cyclosporine A, topical dermal formulations of NSAIDs) have shown an acceptable safety profile in older patients, as well as rituximab. A rigorous evaluation of the medical history of older patients is essential when drugs included in the EULAR guidelines are prescribed, with special attention to factors frequently related to ageing, such as polypharmacy, the existence of organ-specific comorbidities, or the enhanced susceptibility to infections.

Association between anorexia and hyposalivation in community-dwelling older adults in Japan: a 6-year longitudinal study

BACKGROUND

Hyposalivation is associated with the nutritional status. Anorexia of ageing, defined as an age-related decrease in appetite and food intake, presents even in healthy adults and is considered an independent predictor of malnutrition, frailty, and mortality. However, the relationship between anorexia and hyposalivation of ageing is unclear. Thus, the present longitudinal study aimed to investigate the incidence of hyposalivation and its relationship with anorexia in community-dwelling older people in Japan.

METHODS

The study population comprised 220 individuals (80 men and 140 women) aged 65-86 years at baseline. The participants underwent comprehensive health check-ups, including dental examinations and anthropometry, and face-to-face interviews in 2013 and 2019. Hyposalivation was determined on the basis of the unstimulated salivary flow rate measured using the modified cotton roll method. Anorexia was defined as a score of ≤29 in the Japanese version of the Council on Nutrition Appetite Questionnaire. Logistic regression analyses were used to test whether the presence of anorexia at baseline was an independent predictor of hyposalivation.

RESULTS

Hyposalivation developed at a rate of 19.5% during the 6-year observation period. Anorexia was observed in 95 (43.2%) participants at baseline. After adjusting for potential confounding factors, anorexia (adjusted odds ratio [AOR], 2.65; 95% confidence interval [CI], 1.26-5.57) and polypharmacy (AOR, 3.29; CI, 1.06-10.19) were significant predictors of hyposalivation.

CONCLUSION

Loss of appetite is independently correlated with and a risk factor for hyposalivation in older adults. Anorexia of ageing may have negative effects on the salivary flow rate in such settings. Salivation should be a standard feature in clinical assessments of the older adults.

Prevalence of hyposalivation in older people: A systematic review and meta-analysis

BACKGROUND

The proportion of elders is increasing worldwide, and hyposalivation has been associated with the ageing process. Therefore, there has been growing interest in the frequency of hyposalivation in older people since it can cause transient or permanent problems that could affect oral health.

OBJECTIVE

To determine the prevalence of hyposalivation in older people (aged ≥ 60 years).

METHODS

The review was registered at Prospero - International Prospective Register of Systematic Reviews under number CRD42018106322. The search was performed in six electronic databases (Embase, LILACS, Medline, PubMed, Web of Science and Abstracts in Social Gerodontology) and grey literature (Google Scholar) for articles published up to February 2019. The methodology of selected studies was evaluated using the Meta-Analysis of Statistics Assessment and Review (MAStARI) risk of bias checklist. Meta-analyses were performed using Medcalc and Stata 15.

RESULTS

Thirteen studies totalising 3,885 individuals (≥60 years) were included in this systematic review. The meta-analysis showed an overall hyposalivation prevalence of 33.37% (95% confidence interval [CI] 23.90 - 43.57, P < .0001, n = 3,447). The prevalence of hyposalivation for unstimulated and stimulated methods was 33.39% (95% CI 21.08 - 46.96, P < .0001, n = 2,425 individuals) and 30.47% (95% CI 22.53-39.04, P < .0001, n = 1,495 individuals), respectively. Most of the studies were evaluated as low risk of bias. Some study limitations were related to the observational studies potential risk of bias, and different criteria to measure saliva flow rate.

CONCLUSION

This study suggests that the overall prevalence of hyposalivation in older people is 33.37%. When considering stimulated methods, the prevalence of hyposalivation was slightly lower (30.47%).

Endogenous salivary citrate is associated with enhanced rheological properties following oral capsaicin stimulation

NEW FINDINGS

What is the central question of this study? What are the relationships between physical properties of saliva, protein composition and metabolite composition? What is the main finding and its importance? Salivary citrate, one of the major endogenous metabolites in saliva, increased upon capsaicin stimulation and was associated with improved physical properties measured by extensional rheology. This suggests salivary gland citrate transporters might be a valuable area of future study.

ABSTRACT

Saliva displays viscoelastic properties which enable coating, lubrication and protection of the oral mucosa and hard tissues. Individuals lacking saliva or perceiving oral dryness can manage their symptoms using artificial saliva preparations, but these often fail to mimic the sensation and functionality of natural saliva. It is widely acknowledged that mucins (MUC7 and MUC5B) confer saliva's rheological properties, but artificial saliva containing purified mucins is still often an inadequate substitute. This work aimed to explore salivary components that influence salivary extensional rheology to better understand how natural saliva could be replicated. Saliva was stimulated via control and capsaicin solutions in healthy volunteers. Extensional rheology was analysed using a CaBER-1 (capillary breakup) extensional rheometer. Protein composition, including mucins, was measured by gel-electrophoresis band densitometry and metabolites were measured by 1 H nuclear magnetic resonance spectroscopy. Capsaicin stimulation significantly increased capillary breakup time, extensional viscosity and the abundance of most major salivary proteins. Stimulation also increased salivary citrate and choline concentrations. Significant correlations were found between capillary breakup time and amylase (r = 0.67, P < 0.05), statherin (ρ = 0.66, P < 0.05) and citrate (ρ = 0.81, P < 0.01). The relationship between citrate and salivary rheology was subsequently investigated in vitro. These results suggest that citrate and non-mucin proteins are stronger predictors of salivary rheology than the more often studied mucin glycoproteins. Potential mechanisms are discussed and future work in this area could help formulate more effective saliva substitutes, more closely resembling natural saliva.

Intra- and inter-investigator reliabilities of oral moisture measured using an oral moisture-checking device

BACKGROUND

Oral mucosal moisture determined using oral moisture-checking devices is used as a mouth dryness evaluation method. Such devices are capable of evaluating the state of mouth dryness in a simple manner and have applicability in a wide range of subjects; however, their intra- and inter-investigator reliabilities have not yet been clarified.

OBJECTIVE

This study aims to investigate the intra- and inter-investigator reliabilities of measuring oral moisture using an oral moisture-checking device for a wide range of age groups.

METHODS

Intra- and inter-investigator reliabilities were investigated in 28 young subjects and 19 older subjects aged ≥65 years. Three trained investigators independently measured oral mucosal moisture values using an oral moisture-checking device. Intra-investigator reliability was assessed using the coefficient of variation (CV) and intraclass correlation coefficient (ICC) (1.1), and inter-investigator reliability was assessed using ICC (2.1).

RESULTS

Mean CV was 0.015 and 0.016, mean ICC (1.1) was 0.806 and 0.877, and ICC (2.1) was 0.873 and 0.829 in the young and older subjects, respectively.

CONCLUSION

In young subjects, the mean values of ICC (1.1) and ICC (2.1) of the oral moisture-checking device were 0.806 and 0.873, respectively, whereas in older subjects, these values were 0.877 and 0.829, respectively. Thus, this confirms that the examination of oral mucosal moisture using the oral moisture-checking device has sufficient intra- and inter-investigator reliabilities for a wide range of age groups.

Artificial Saliva: Challenges and Future Perspectives for the Treatment of Xerostomia

The chronic sensation of a dry mouth is a disease condition called xerostomia and affects a large part of the population. Xerostomia is associated with decreased secretion, or more often, qualitative changes in saliva proteins and immunoglobulin concentrations that develop as a result of salivary gland dysfunction. Several reasons causing dry mouth were described, and usually, they include taking medications, diseases or radiotherapy. In some situations, when it is difficult to use salivary stimulants or salivary gland damage is irreversible, the only option might seem to be saliva substitutes. The paper presents the most important aspects considering saliva preparations. The rheological and lubricating properties and the reconstruction of the complex saliva structure has been the main purpose of research. The biological properties of saliva preparations were also widely discussed. As part of the work, the antimicrobial effect of three commercial saliva preparations was tested. Finally, inadequate antimicrobial properties against the strains isolated from the oral cavity were demonstrated. The development of salivary substitutes, in particular, the improvement of antimicrobial properties, can be achieved using nanotechnology, including drug delivery systems containing nanocarriers.

[Role and mechanism of muscarinic acetylcholine receptor in the regulation of submandibular gland secretion]

Muscarinic acetylcholine receptors (mAChRs), including M1-M5 subtypes, are classic receptors in regulating water, ion, and solute transport in salivary gland. Our work focuses on the studies on the expression pattern and function of mAChR in the submandibular gland (SMG), and the underlying mechanism involved in the mAChR-regulated secretion, together with the effect of parasympathectomy on the salivary secretion. Microvascular autotransplantation of SMG into the temporal fossa provides a continuous and endogenous source of fluids, and is currently an effective method for treating severe keratoconjunctivitis sicca. By using RT-PCR, Western blotting, and immunofluorescence, our data demonstrated that the expression of M1 and M3 subtypes were decreased in latent period in rabbit SMG autotransplantation model, whereas carbachol stimulation promoted the salivary secretion, as well as M1 and M3 expressions. By contrast, mAChRs were hypersensitive in epiphora SMGs, whereas atropine gel and botulinum toxin A application significantly inhibited the hypersecretion in both animal models and patients. Furthermore, the possible intracellular signal molecules involved in the mAChR-modulated salivary secretion were explored. Activation of mAChR upregulated the expression of aquaporin 5 (AQP5), the main transporter that mediated water secretion through transcellular pathway, and led to AQP5 trafficking from lipid rafts to non-lipid microdomain. Extracellular signal-regulated kinase 1/2 (ERK1/2) was involved in the mAChR-regulated AQP5 content. mAChR activation also modulated the expression, distribution, and function of tight junction proteins, and increased paracellular permeability. ERK1/2/β-arrestin2/clathrin/ubiquitin signaling pathway was responsible for the mAChR-regulated downregulation of tight junction molecule claudin-4. Cytoskeleton filamentous actin (F-actin) was also involved in the distribution and barrier function of epithelial tight junctions. Besides, endothelial tight junctions were opened by mAChR agonist-evoked salivation in the mice. Furthermore, parasympathetic denervation increased resting salivary secretion in the long terminrats and minipigs. Taken together, our work demonstrated that mAChR regulated saliva secretion via transcellular and paracellular pathways in SMG epithelium as well as tight junction opening in SMG endothelium. Modulation of mAChR might be a promising strategy to ameliorate SMG dysfunction.