Salivary glands epithelial and myoepithelial cells are major vitamin D targets

Dental caries in children and vitamin D deficiency: a narrative review

Dental caries represents one of the most prevalent health problems in childhood. Numerous studies have assessed that vitamin D deficiency is highly related to dental caries in primary and permanent teeth in children. The aim of this study is to elaborate a narrative review about proposed mechanisms by which vitamin D deficiency interacts with dental caries process in children. Vitamin D deficiency during pregnancy may cause intrauterine enamel defects, and through childhood is accompanied by insufficient activity of antibacterial peptides, decreased saliva secretion, and a low level of calcium in saliva.  Conclusion: In conclusion, vitamin D deficiency would increase the risk of caries in the primary and/or permanent dentition. Relationship between vitamin D deficiency and dental caries is evident enough for vitamin D deficiency to be considered as a risk factor for dental caries in children. Optimal levels of vitamin D throughout pregnancy and childhood may be considered an additional preventive measure for dental caries in the primary and permanent dentition.

Dry Eye Disease: What Is the Role of Vitamin D?

Dry eye disease (DED) is a multifactorial condition resulting from reduced tear secretion from the lacrimal glands, increased tear water evaporation or the production of poor-quality tears. Such tear instability can lead to inflammation and damage of the ocular surface, as well as to abnormal nociception. Historically, tear substitutes and corticosteroids have been the bastion of DED therapy, but a substantial number of patients still suffer from residual symptoms even after being treated with traditional treatments. Aiming to find safe and effective alternative therapies, recent efforts have been focused on the role of vitamin D in the cellular physiology of the eye. Possibly because of its positive effect in modulating the immune and inflammatory responses, the systemic supplementation of vitamin D seems, indeed, to be an effective therapeutic strategy, especially, but not only, for patients affected by DED that does not respond to conventional treatments. In this context, this review focuses on the literature reporting on the pathogenesis and treatment of DED, with a special emphasis on the recent investigations reporting on the potential role of the systemic administration of vitamin D as a therapeutic approach in the management of such condition.

Effect of oral vitamin D supplementation on dry eye disease patients with vitamin D deficiency

CLINICAL RELEVANCE

Dry eye disease (DED) and vitamin D deficiency are both common clinical entities. Vitamin D has been reported to play a significant role in ocular surface homeostasis.

BACKGROUND

This study aimed to determine the therapeutic effect of oral vitamin D supplementation in dry eye disease patients with vitamin D deficiency.

METHODS

A randomized, controlled study was completed in 100 patients with dry eye disease and concurrent vitamin D deficiency (< 20 ng/ml). Participants were randomly allocated to 8 weeks of oral vitamin D supplementation with both groups receiving conventional dry eye treatment with artificial tears. Schirmer's, tear break-up time (TBUT) and osmolarity tests were measured before and after eight weeks of treatment.

RESULTS

The mean age of participants was 36.8 ± 8.56 years in the treatment group (n: 50) and 34.8 ± 10.13 year in the control group (n: 50). After eight weeks of treatment the mean differences in Schirmer's, TBUT and tear osmolarity were 2.38 ± 1.55 mm, 3.95 ± 1.48 s and -16.9 ± 6.28 mOsm/L, respectively in the treatment group, and 0.7 ± 0.86 mm, 0.92 ± 1.57s and -3.34 ± 2.0 mOsm/L respectively in the control group (p < 0.001 for all parameters). The treatment group demonstrated a more significant improvement than the control group in Schirmer<apos;>s, TBUT and osmolarity values (p < 0.001).

CONCLUSION

Vitamin D supplementation as an adjuvant to routine dry eye treatment improves ocular surface hemostasis parameters, results in better tear stability and a more improved tear osmolarity in patients with vitamin D deficiency.

Protective effect of nano vitamin D against fatty degeneration in submandibular and sublingual salivary glands: A histological and ultrastructural study

BACKGROUND

Poor nutritional habits and a low level of physical activity are associated with obesity, leading to increased caloric and fat intakes. A high-fat diet can significantly impact oral health through the accumulation of lipids in the salivary glands, which ultimately affect salivary gland function. Recently, an increasing number of supplement nano-formulations, such as nano vitamin D, have become available. However, only few studies have explored the effects of nano vitamin D on the maintenance of oral health.

OBJECTIVE

This study aimed to compare the histological effects of nano vitamin D to those of regular vitamin D on fatty degeneration in submandibular and sublingual salivary glands using a rat model.

METHODS

Twenty-four adult male albino Sprague-Dawley rats were divided into the following groups: untreated group, high-fat diet group, high-fat diet and regular vitamin D group, and high-fat diet and nano vitamin group.Thereafter, samples of the submandibular and sublingual salivary glands were dissected for histological and electron microscopic studies. Morphometric digital image analysis was used to quantitatively measure the changes in the size and number of acini and secretory granules.

RESULTS

Regular vitamin D had a partial protective effect. However, vitamin D could fully restore cellular structures to their normal state, thereby protecting against fatty degeneration of the salivary tissue and immune cell infiltration, particularly in the submandibular serous tissue. Nano vitamin D was more efficacious than regular vitamin D at restoring the number and size of submandibular serous secretory granules.

CONCLUSION

Employing nano vitamin D as a supplement to high-fat diets could protect against high-fat diet-induced salivary gland damage in rats.

VDR in salivary gland homeostasis and cancer

The vitamin D receptor (VDR) and its ligand 1,25(OH)₂D₃ (1,25D) impact differentiation and exert anti-tumor effects in many tissues, but its role in salivary gland has yet to be defined. Using immunohistochemistry (IHC), we have detected strong VDR expression in murine and human salivary gland ducts. Compared to normal gland, VDR protein expression was retained in differentiated human pleomorphic adenoma (PA) but was undetectable in undifferentiated PA and in carcinomas, suggesting deregulation of VDR during salivary cancer progression. To gain insight into the potential role of VDR in salivary cancer, we assessed the effects of vitamin D in vivo and in vitro. Despite the presence of VDR in salivary gland, chronic dietary vitamin D restriction did not alter morphology of the salivary epithelium in C57/Bl6 mice. The localization of VDR in ductal epithelium prompted us to examine the effects of 1,25D in an established cell line (mSGc) derived from normal murine submandibular gland (SMG). This previously characterized cell line consists of multiple stem, progenitor and differentiated cell types as determined by mutually exclusive cellular expression of basal, ductal and myoepithelial markers. We demonstrated VDR expression and regulation of VDR target genes Vdr and Postn by 1,25D in mSGc, indicating functional ligand-mediated transcriptional activity. The effect of VDR signaling on epithelial differentiation markers was assessed by qPCR and IHC in mSGc cells treated with 1,25D. We found that 1,25D reduced mRNA expression of the basal cell progenitor marker keratin 5 (K5) and increased expression of the differentiated ductal cell marker keratin 7 (K7). Further, we found that 1,25D significantly decreased the number of proliferating cells, including proliferating K5⁺ cells. Characterization of cell cycle by Muse cytometry indicated 1,25D treatment decreased cells in S, G₂, and M phase. The inhibition of K5⁺ cell proliferation by 1,25D is of particular interest because K5⁺ basal cells contribute to a wide variety of salivary tumor types. Our studies suggest that 1,25D alters cancer-relevant progenitor and differentiation markers in the salivary gland.

Conjunctival impression cytology and tear-film changes in cases with vitamin D deficiency

PURPOSE

To evaluate conjunctival surface cells and tear-film functions in cases with vitamin D deficiency.

METHODS

Thirty-six patients with serum vitamin D deficiency and 27 control subjects with normal serum vitamin D levels were included in this prospective study. The tear break-up time (TBUT), Schirmer II test, and conjunctival impression cytology tests were performed to all participants.

RESULTS

The mean serum vitamin D levels were 10.5 ± 5.0 µl in the study group and 33.9 ± 11.7 µl in the control group (p < 0.001). The median TBUT scores were 11 s and 17 s and the median Schirmer II values were 7.5 mm and 12 mm in the study and the control groups, respectively (p = 0.003, p = 0.049). According to the Nelson staging system, 69.4% of the patients in the study group had grade 2 or 3 impression cytology, whereas 18.5% of the participants in the control group had grade 2 or 3 impression cytology (p < 0.001).

CONCLUSION

Our study results showed that vitamin D deficiency may lead to dry eye causing conjunctival squamous metaplasia and loss of goblet cells on the ocular surface.

Correlation of vitamin D levels with tear film stability and secretion in patients with dry eye syndrome

PURPOSE

To investigate tear film stability and secretion according to serum 25-hydroxyvitamin D3 [25(OH)D] levels in dry eye patients.

METHODS

In this retrospective observational study, the medical charts of 92 patients who visited the Department of Ophthalmology at Hallym University Kangnam Sacred Heart Hospital from April to August 2015 were reviewed. Serum 25(OH)D levels were measured. Subjects were divided into three groups according to serum 25(OH)D levels: sufficient, inadequate or deficient group. Eye discomfort was measured by ocular surface disease index (OSDI). Tear break-up time (TBUT), fluorescein staining score and Schirmer's tear secretion test were measured.

RESULTS

The mean age was 53.38 ± 13.69 years. Mean serum 25(OH)D level was 14.41 ± 5.98 ng/ml. Tear break-up time (TBUT) and tear secretion were positively correlated with serum 25(OH)D levels (r = 0.389, p = 0.001; and r = 0.428, p < 0.001, Pearson correlation test). Tear break-up time (TBUT) and tear secretion were shorter in the vitamin D-deficient group compared to the sufficient group (p = 0.022 and p = 0.004). Fluorescein staining scores and OSDI scores were not different between the three groups.

CONCLUSION

Tear break-up time (TBUT) and secretion were correlated with serum vitamin D levels. Vitamin D status may be an important factor for dry eye syndrome.

Vitamin D deficiency changes the intestinal microbiome reducing B vitamin production in the gut. The resulting lack of pantothenic acid adversely affects the immune system, producing a "pro-inflammatory" state associated with atherosclerosis and autoimmunity

STUDY OBJECTIVES

Vitamin D blood levels of 60-80ng/ml promote normal sleep. The present study was undertaken to explore why this beneficial effect waned after 2years as arthritic pain increased. Pantothenic acid becomes coenzyme A, a cofactor necessary for cortisol and acetylcholine production. 1950s experiments suggested a connection between pantothenic acid deficiency, autoimmune arthritis and insomnia. The B vitamins have been shown to have an intestinal bacterial source and a food source, suggesting that the normal intestinal microbiome may have always been the primary source of B vitamins. Review of the scientific literature shows that pantothenic acid does not have a natural food source, it is supplied by the normal intestinal bacteria. In order to test the hypothesis that vitamin D replacement slowly induced a secondary pantothenic acid deficiency, B100 (100mg of all B vitamins except 100mcg of B12 and biotin and 400mcg of folate) was added to vitamin D supplementation.

METHODS

Vitamin D and B100 were recommended to over 1000 neurology patients. Sleep characteristics, pain levels, neurologic symptoms, and bowel complaints were recorded by the author at routine appointments.

RESULTS

Three months of vitamin D plus B100 resulted in improved sleep, reduced pain and unexpected resolution of bowel symptoms. These results suggest that the combination of vitamin D plus B100 creates an intestinal environment that favors the return of the four specific species, Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria that make up the normal human microbiome.

HYPOTHESES

1) Seasonal fluctuations in vitamin D levels have normally produced changes in the intestinal microbiome that promoted weight gain in winter. Years of vitamin D deficiency, however, results in a permanently altered intestinal environment that no longer favors the "healthy foursome". 2) Humans have always had a commensal relationship with their intestinal microbiome. We supplied them vitamin D, they supplied us B vitamins. 3) The four species that make up the normal microbiome are also commensal, each excretes at least one B vitamin that the other three need but cannot make. 4) Improved sleep and more cellular repairs eventually depletes body stores of pantothenic acid, causing reduced cortisol production, increased arthritic pain and widespread "pro-inflammatory" effects on the immune system. 5) Pantothenic acid deficiency also decreases available acetylcholine, the neurotransmitter used by the parasympathetic nervous system. Unopposed, increased sympathetic tone then produces hypertension, tachycardia, atrial arrhythmias and a "hyper-adrenergic" state known to predispose to heart disease and stroke.

Low Serum 25-Hydroxyvitamin D Levels Are Associated with Dry Eye Syndrome

Background

Dry eye syndrome (DES) is a common tear film and ocular surface disease that results in discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. Systemic diseases associated with DES include diabetes mellitus, rheumatoid arthritis, depression, anxiety, thyroid disease, allergic diseases, irritable bowel syndrome, chronic pain syndrome, and hyperlipidemia. Interestingly, it has been found that most of these are associated with low levels of serum 25-hydroxyvitamin D (25(OH)D) or inadequate sunlight exposure.

Methods

In this cross-sectional data analysis, noninstitutionalized adults aged ≥19 years (N = 17,542) who participated in Korean National Health and Nutrition Examination Survey 2010–2012 were included. Information regarding duration of sunlight exposure was collected from the survey participants. Serum 25(OH)D and zinc levels were measured. The confounding variables were age, gender, sunlight exposure time, region of residence, obesity, serum 25(OH)D level, diabetes mellitus, rheumatoid arthritis, depression, thyroid disorder, atopic dermatitis, history of ocular surgery, regular exercise, and walking exercise.

Results

Mean serum 25(OH)D levels of subjects with and without DES were 16.90 ± 6.0 and 17.52 ± 6.07 (p<0.001). Inadequate sunlight exposure time (odds ratio [OR], 1.554; 95% confidence interval [CI], 1.307–1.848), urban residence (OR, 1.669; 95% CI, 1.456–1.913), indoor occupation (OR, 1.578; 95% CI, 1.389–1.814), and low serum 25(OH)D level (OR, 1.158; 95% CI, 1.026–1.308) were the risk factors for DES. After adjusting for age, sex, obesity, diabetes mellitus, rheumatoid arthritis, depression, thyroid disorder, atopic dermatitis, history of ocular surgery, regular exercise, and occupation, low serum 25(OH)D level (OR, 1.178; 95% CI, 1.010–1.372) and deficient sunlight exposure time (OR, 1.383; 95% CI, 1.094–1.749) were the risk factors for diagnosed DES.

Conclusion

Low serum 25(OH)D levels and inadequate sunlight exposure are associated with DES in Korean adults. These results suggest that sufficient sunlight exposure or vitamin D supplementation may be useful in DES treatment.