Inducible nitric oxide synthase-mediated injury in a mouse model of acute salivary gland dysfunction

Effectiveness of thyme honey in the management of xerostomia in geriatric patients with end-stage renal disease: a randomized controlled clinical trial with a biochemical assessment

BACKGROUND

Taking into consideration the value of the oral health condition in geriatric people with end-stage renal disease (ESRD) associated with xerostomia and believing that salivary stimulants or substitutes could potentially be used to manage this condition. This study aimed to evaluate the clinical effectiveness of thyme honey as oral rinse in geriatric patients with ESRD using the subjective dry mouth score as a primary objective and to assess the effect of thyme honey on the salivary nitric oxide level, salivary flow rate, and salivary ph in addition to objective dry mouth score as a secondary objective.

METHODS

This was a single blinded randomized controlled trial with two equal arms, the interventional arm (thyme honey oral rinse) and the control arm (saline). Twenty-eight geriatric patients with ESRD undergoing hemodialysis complained of xerostomia were recruited from the renal dialysis center. Patients in both arms followed the same administration protocol either with thyme honey oral rinse or saline. The following clinical parameters (the subjective and objective dry mouth scores, salivary flow rate, salivary ph, and salivary nitric oxide (NO) levels) were evaluated for both groups at different intervals (baseline, 1 week, and 1 month).

RESULTS

In the current study, it was found that both the subjective and objective dry mouth scores were significantly lower after one month of using thyme honey oral rinse (1.86 ± 0.66B) and (2.21 ± 0.43B) respectively, than the control group (3.07 ± 0.73B) and (3.07 ± 0.83B), respectively with a (p < 0.001). Also, the salivary flow rate was significantly higher after one month of using thyme honey oral rinse (1.56 ± 0.51A), than the control group (0.78 ± 0.27A) with a (p < 0.001). For the NO levels, there was a significant increase in measured value after 1 month in the intervention group (p < 0.001), while for the control group the change was not statistically significant (p = 0.166).

CONCLUSIONS

The results of the current study have revealed the efficacy of Thyme honey oral rinse in the management of xerostomia in geriatric patients with ESRD. Trial registration The ClinicalTrials.gov Identifier for this study is NCT05247008.

The role of salivary gland macrophages in infection, disease and repair

Macrophages are mononuclear innate immune cells which have become of increasing interest in the fields of disease and regeneration, as their non-classical functions have been elucidated in addition to their classical inflammatory functions. Macrophages can regulate tissue remodeling, by both mounting and reducing inflammatory responses; and exhibit direct communication with other cells to drive tissue turnover and cell replacement. Furthermore, macrophages have recently become an attractive therapeutic target to drive tissue regeneration. The major salivary glands are glandular tissues that are exposed to pathogens through their close connection with the oral cavity. Moreover, there are a number of diseases that preferentially destroy the salivary glands, causing irreversible injury, highlighting the need for a regenerative strategy. However, characterization of macrophages in the mouse and human salivary glands is sparse and has been mostly determined from studies in infection or autoimmune pathologies. In this review, we describe the current literature around salivary gland macrophages, and speculate about the niches they inhabit and how their role in development, regeneration and cancer may inform future therapeutic advances.

Innate Immunity and Biological Therapies for the Treatment of Sjögren's Syndrome

Sjögren's syndrome (SS) is a systemic autoimmune disorder affecting approximately 3% of the population in the United States. This disease has a female predilection and affects exocrine glands, including lacrimal and salivary glands. Dry eyes and dry mouths are the most common symptoms due to the loss of salivary and lacrimal gland function. Symptoms become more severe in secondary SS, where SS is present along with other autoimmune diseases like systemic lupus erythematosus, systemic sclerosis, or rheumatoid arthritis. It is known that aberrant activation of immune cells plays an important role in disease progression, however, the mechanism for these pathological changes in the immune system remains largely unknown. This review highlights the role of different immune cells in disease development, therapeutic treatments, and future strategies that are available to target various immune cells to cure the disease.

Comparison of salivary nitric oxide and oral health in diabetic patients with and without xerostomia

BACKGROUND AND OBJECTIVE

Diabetes mellitus (DM) is a chronic multi-systemic metabolic disorder; diabetic patients are more prone to xerostomia and oral health problems than others. There are evidences that nitric oxide (NO) plays an important role in healthy salivary gland function, prevention of insulin resistance and progression of diabetes mellitus. The aim of this study was to compare the salivary NO level between type 2 diabetic (T2DM) patients with and without xerostomia.

METHODS

In this case control study, 70 patients with T2DM, which were matched according to age, sex, type of disease control, were enrolled conveniently. The subjects based on abeslang test were allocated to the two groups; 35 patients with xerostomia and 35 patients without xerostomia. Unstimulated whole saliva was collected by spitting method. NO levels was measured by ELISA method using Griess reaction. Data was analyzed using t-test, ANOVA and logistic regression analysis to examine the association of salivary NO and xerostomia.

RESULTS

The mean and standard deviation of salivary NO in the diabetic subjects with xerostomia was significantly lower than diabetic subjects without xerostomia (138 ± 94.58 μmol/L vs. 356.61 ± 302.81 μmol/L (P-value = 0.001). In logistic regression analysis, salivary NO level was associated with 0.994 fold decreased risk of xerostomia in diabetic subjects after adjustment for age, gender, FBS and HbA1c.

CONCLUSIONS

The present study indicates salivary nitric oxide level was a predictor of xerostomia in diabetic patients. More longitudinal studies are necessary to understand the association of salivary NO level with diabetes-induced xerostomia.

Salivary glands require Aurora Kinase B for regeneration after transient innate immune-mediated injury

Severe, irreversible salivary gland disease and oral dryness is experienced by sufferers of Sjögren’s syndrome and those treated with irradiation for head and neck cancer. Therefore, major efforts have been made in the last decade to unravel key molecular signals that can drive salivary gland (SG) regeneration and functional restoration. However, the earliest molecular determinants that accompany SG regeneration remain incompletely defined. The present study examined the initial mitogenic events marking the regenerative response of the murine submandibular gland (SMG), following innate immune-mediated injury. Local intraductal administration of the synthetic double stranded (ds) RNA polyinosinic-polycytidylic acid (poly (I:C)) widely, but transiently, depleted the acinar and progenitor cells, 24 hours post poly (I:C) introduction. While the progenitor and duct cells started to proliferate and expand at 72 hours, the Mist1-positve acinar cells did not re-appear until 96 hours post poly (I:C) injury. The cellular replenishment during regeneration involved significant upregulation of the cell cycle promoter Aurora kinase B (AURKB). AURKB, which is expressed in healthy proliferating and cancerous cells, is a serine/threonine protein kinase, well known to orchestrate key events in cell division and cytokinesis. However, the expression and role of AURKB in regeneration of post mitotic salivary gland cells has not been previously explored. In vivo inhibition of AURKB using the selective inhibitor Barasertib (AZD1152-HQPA) interfered with SMG recovery from the transient, but severe poly (I:C)-mediated injury and cellular depletion. AURKB deficiency during regeneration of the injured tissues: disrupted cell cycle progression, repressed renewal of Mist1-positive acinar cells and prevented recovery of salivary secretion. The knowledge gained in this study may be utilized in the development of therapeutic targets for irreversible salivary gland disease.