Changes in Saliva Rheological Properties and Mucin Glycosylation in Dry Mouth

Abstract

Saliva is vital for the maintenance of normal oral physiology and mucosal health. The loss of salivary function can have far-reaching consequences, as observed with dry mouth, which is associated with increased orodental disease, speech impairment, dysphagia, and a significant negative effect on quality of life. The timely diagnosis of oral dryness is vital for the management of orodental disease and any associated often-undiagnosed systemic disease (e.g., Sjögren syndrome). Our aim was to investigate differences in mucin glycoproteins and saliva rheological properties between sufferers and nonsufferers of dry mouth in order to understand the relationship between saliva composition, rheological properties, and dryness perception and provide additional potential diagnostic markers. All patients exhibited objective and subjective oral dryness, irrespective of etiology. Over half of the patients (n = 20, 58.8%) had a saliva secretion rate above the gland dysfunction cutoff of 0.1 mL/min. Mucin (MUC5B and MUC7) concentrations were generally similar or higher in patients. Despite the abundance of these moisture-retaining proteins, patients exhibited reduced mucosal hydration (wetness) and significantly lower saliva spinnbarkeit (stringiness), suggesting a loss of the lubricating and retention/adhesion properties of saliva, which, at least partially, are associated with mucin glycoproteins. Over 90% of patients with dry mouth (DMPs) consistently had unstimulated whole mouth saliva (UWMS) spinnbarkeit below the proposed normal cutoff (10 mm). Further analysis of mucins revealed the reduced glycosylation of mucins in DMPs compared to healthy controls. Our data indicate that UWMS mucin concentrations are not reduced in dry mouth but that the mucin structure (glycosylation) is altered. UWMS from DMPs had reduced spinnbarkeit, the assessment of which, in conjunction with sialometry, could improve sensitivity for the diagnosis of dry mouth. Additionally, it may be useful to take into consideration the altered mucin glycosylation and saliva rheological properties when designing synthetic or purified mucins for saliva substitutes and dry mouth therapy.

Early salivary changes in multiple myeloma patients undergoing autologous HSCT

“…The dryness component of the OMNI score was negatively correlated with UWS flow rate and, although no significant changes in MUC5B concentrations were observed, positively correlated with SWS MUC5B levels. This counterintuitive finding is supported by another study where patients with xerostomia had similar or higher MUC5B and MUC7 concentrations, combined with differences in the glycosylation of the mucins (Chaudhury et al., ). We conclude that the correlation may be based on reduced total MUC5B availability or changed lubricating capabilities of the mucins.…”

“…As suggested by the dryness component of the OMNI score, xerostomia was present during the whole study period. Xerostomia has been linked to changes in the lubricating protein MUC5B (Chaudhury, Shirlaw, Pramanik, Carpenter, & Proctor, ; Dijkema et al., ). The dryness component of the OMNI score was negatively correlated with UWS flow rate and, although no significant changes in MUC5B concentrations were observed, positively correlated with SWS MUC5B levels.…”

Abnormalities in acute salivary biochemical characteristic responses to gustatory stimulation with citric acid in chronic non‐atrophic gastritis

“…This suggests that reduced TPD may be a cause of dry mouth in CNAG, although whether mucin glycoprotein lead to dry mouth still remains uncertain, and ascend unstimulated SFR may be related to the feedback adjustment of salivary glands caused by dry mouth. Additionally, there are other factors that can influence dry mouth perception, such as genetic variation in sensitivity, salivary rheological properties, and mucin glycosylation . For a more specific understanding of salivary characteristics lead to dry mouth in CNAG, salivary rheological properties and mucin glycosylation should be detected in the future study.…”

A review of diet standardization and bolus rheology in the management of dysphagia

“…This was attributed to the effect of alpha-amylase, but a general dilution effect may also have contributed [18]. Saliva varies widely in quality and quantity: one "dry-mouth" group -Sjögren's syndrome (SS) -also showed dramatically reduced mucin content and stringiness ("spinnbarkeit") of saliva [22].…”