Vitamin D Levels and Associations in Indian Patients with Primary Sjögren's Syndrome

Vitamin D Deficiency in Primary Sjögren's Syndrome: Association with Clinical Manifestations and Immune Activation Markers

Vitamin D is an agent involved in bone and mineral homeostasis. It has been recognized as a potent immunomodulator. It has immune-enhancing properties, and it induces immune tolerance. Vitamin D deficiency has been shown to be related to the development of autoimmune disorders. Vitamin D deficiency has been observed in patients with rheumatoid arthritis (RA) and it has been shown to be related with disease activity. Vitamin D deficiency has also been found in patients with systemic lupus erythematosus (SLE) and it was shown to be related to disease activity and renal involvement. Vitamin D deficiency has also been observed in multiple sclerosis. Vitamin D has been found to act as a supplemental therapeutic agent in multiple sclerosis. Sjögren's syndrome is a systemic autoimmune disease affecting the exocrine glands, known as an autoimmune epithelitis. The disease has a complex pathogenesis, requiring a genetic background, immune cell activation, and autoantibody production. The disease affects the exocrine glands, lacrimal, and salivary glands leading to ocular and oral dryness. Vitamin D levels have been measured in patients with Sjögren's syndrome and an association was observed between low vitamin D levels, peripheral neuropathy and the presence of lymphoma. In other cohorts, such as a Turkish cohort, vitamin D deficiency was observed in patients with Sjögren's syndrome. The aim is to measure serum vitamin D levels in consecutive patients with primary Sjögren's syndrome and investigate the relationship between vitamin D levels and the presence of immunologic markers, clinical, serological, and histopathological characteristics.

Vitamin D and connective tissue diseases

OBJECTIVE AND DESIGN

Recently, many studies have shown that the biologically active form of vitamin D-1,25(OH)₂ D-is involved in many biological processes, including immune system modulation, and patients affected by various autoimmune diseases, such as connective tissue diseases (CTD), showed low levels of vitamin D. It is not clear if vitamin D deficiency is involved in the pathogenesis of autoimmune diseases or it is a consequence.

MATERIAL

We carried out a review of literature to summarize the existing connections between 25-OH vitamin D and CTD.

METHODS

We searched for articles on PubMed by keywords: vitamin D, connective tissue diseases, systemic lupus erythematosus, Sjogren's syndrome, systemic sclerosis, undifferentiated connective tissue disease.

RESULTS

The relationship between vitamin D and CTD is still not very clear, despite many studies having been performed and some data suggest a connection between these diseases and 25-OH vitamin D levels.

CONCLUSIONS

The limitations of the study, such as the heterogeneity of patients, methods used to measure vitamin D serum concentration and other biases, do not lead to unequivocal results to demonstrate a direct link between low vitamin D serum levels and autoimmune diseases. Further studies are needed to resolve conflicting results.

Hepatitis B virus downregulates vitamin D receptor levels in hepatoma cell lines, thereby preventing vitamin D-dependent inhibition of viral transcription and production

Background

Vitamin D is a key immune-modulator that plays a role in the innate and adaptive immune systems. Certain pathogens impair the immune defense by downregulating the vitamin D receptor (VDR) pathway. Low serum levels of vitamin D are associated with increased hepatitis B virus (HBV) replication. Our study aimed to assess the in-vitro relationship between HBV production and Vitamin D signaling pathway and to explore the associated mechanism(s).

Methods

HBV transcription and replication was evaluated by qRT-PCR of the HBV-RNA and covalently closed circular DNA (cccDNA). Furthermore, we have transfected the 1.3 X HBV-Luc plasmid to the cells and measured the Luciferase activity using Luminometer. Vitamin D signaling pathway activation was evaluated by measuring the expression levels of VDR, CYP24A1, Tumor necrosis factor α (TNFα) and cathelicidin (CAMP) by qRT-PCR. All assays were performed on HepG2.2.15, HepG2, and HepAD38 cells treated with or without Vitamin D active metabolite: calcitriol.

Results

Calcitriol did not suppress HBV transcription, cccDNA expression or HBV RNA levels in HepG2.2.15 cells. However, VDR transcript levels in HepG2.215 cells were significantly lower compared to HepG2 cells. Similar results were obtained in HepAD38 cell where VDR expression was down-regulated when HBV transcript level was up-regulated. In addition, calcitriol induced VDR-associated signaling, resulting in upregulation of CYP24A1, TNFα and CAMP expression level in HepG2 cells but not in the HepG2.2.15 cells.

Conclusions

These findings indicate that VDR expression is downregulated in HBV-transfected cells, thereby preventing vitamin D from inhibiting transcription and translation of HBV in vitro. HBV might use this mechanism to avoid the immunological defense system by affecting both TNFα and CAMP signaling pathways.

Electronic supplementary material

The online version of this article (10.1186/s10020-018-0055-0) contains supplementary material, which is available to authorized users.