Does vitamin D play a role in autoimmune endocrine disorders? A proof of concept.

In the last few years, more attention has been given to the "non-calcemic" effect of vitamin D. Several observational studies and meta-analyses demonstrated an association between circulating levels of vitamin D and outcome of many common diseases, including endocrine diseases, chronic diseases, cancer progression, and autoimmune diseases. In particular, cells of the immune system (B cells, T cells, and antigen presenting cells), due to the expression of 1α-hydroxylase (CYP27B1), are able to synthesize the active metabolite of vitamin D, which shows immunomodulatory properties. Moreover, the expression of the vitamin D receptor (VDR) in these cells suggests a local action of vitamin D in the immune response. These findings are supported by the correlation between the polymorphisms of the VDR or the CYP27B1 gene and the pathogenesis of several autoimmune diseases. Currently, the optimal plasma 25-hydroxyvitamin D concentration that is necessary to prevent or treat autoimmune diseases is still under debate. However, experimental studies in humans have suggested beneficial effects of vitamin D supplementation in reducing the severity of disease activity. In this review, we summarize the evidence regarding the role of vitamin D in the pathogenesis of autoimmune endocrine diseases, including type 1 diabetes mellitus, Addison's disease, Hashimoto's thyroiditis, Graves' disease and autoimmune polyendocrine syndromes. Furthermore, we discuss the supplementation with vitamin D to prevent or treat autoimmune diseases.

Vitamin D and Autoimmune Diseases: Is Vitamin D Receptor (VDR) Polymorphism the Culprit?

BACKGROUND: Vitamin D deficiency is becoming an increasing problem worldwide. It should not be underestimated, not only due to the well-known consequences vitamin D deficiency has on bone health, but primarily because recent studies have shown how the biologically active form of vitamin D - 1,25(OH)2D - is involved in many biological processes, including immune system modulation. Moreover, the presence of a vitamin D receptor was discovered in almost all immune cells and some of its polymorphisms were found to be associated with increased incidence of autoimmune diseases. This finding led to a proposed link between vitamin D deficiency and autoimmune diseases. Patients affected by various autoimmune diseases showed low levels of vitamin D. However, it is not always clear whether vitamin D deficiency is the cause or rather a consequence of the disease. Limitations of the studies, such as the small number of patients, heterogeneity of selected groups, environmental conditions, methods used to measure vitamin D serum concentration and other confounding factors do not lead to unequivocal results to demonstrate a direct link between low vitamin D levels and autoimmune disease. Therefore, randomized trials are needed to clarify conflicting results.

Unraveling the Hygiene Hypothesis of helminthes and autoimmunity: origins, pathophysiology, and clinical applications.

BACKGROUND: The Hygiene Hypothesis (HH) attributes the dramatic increase in autoimmune and allergic diseases observed in recent decades in Western countries to the reduced exposure to diverse immunoregulatory infectious agents. This theory has since largely been supported by strong epidemiological and experimental evidence. DISCUSSION: The analysis of these data along with the evolution of the Western world's microbiome enable us to obtain greater insight into microorganisms involved in the HH, as well as their regulatory mechanisms on the immune system. Helminthes and their derivatives were shown to have a protective role. Helminthes' broad immunomodulatory properties have already begun to be exploited in clinical trials of autoimmune diseases, including inflammatory bowel disease, multiple sclerosis, rheumatoid arthritis, and type-1 diabetes. SUMMARY: In this review, we will dissect the microbial actors thought to be involved in the HH as well as their immunomodulatory mechanisms as emphasized by experimental studies, with a particular attention on parasites. Thereafter, we will review the early clinical trials using helminthes' derivatives focusing on autoimmune diseases.

Phosphorylcholine-tuftsin compound prevents development of dextransulfate-sodium-salt induced murine colitis: implications for the treatment of human inflammatory bowel disease.

Improved clinical findings of inflammatory bowel disease (IBD) upon treatment with helminthes and their ova were proven in animal models of IBD and in human clinical studies. The immunomodulatory properties of several helminthes were attributed to the phosphorylcholine (PC) molecule. We assessed the therapeutic potential of tuftsin-PC conjugate (TPC) to attenuate murine colitis. Colitis was induced by Dextransulfate-Sodium-Salt (DSS) in drinking water. TPC was given by daily oral ingestion (50 µg/0.1 ml/mouse or PBS) starting at day -2. Disease activity index (DAI) score was followed daily and histology of the colon was performed by H&E staining. Analysis of the cytokines profile in distal colon lysates was performed by immunoblot. Treatment of DSS induced colitis with TPC prevented the severity of colitis, including a reduction in the DAI score, less shortening of the colon and less inflammatory activity in histology. The immunoblot showed that the colitis preventive activity of TPC was associated with downregulation of colon pro-inflammatory IL-1ß, TNFα and IL-17 cytokines expression, and enhancement of anti-inflammatory IL-10 cytokine expression. In the current study, we demonstrated that TPC treatment can prevent significantly experimental colitis induction in naïve mice. We propose the TPC as a novel potential small synthetic molecule to treat colitis.

Vitamin D and autoimmune thyroid diseases: facts and unresolved questions.

Vitamin D deficiency (levels lower than 20 ng/ml) is becoming a global health problem, since it is increasingly represented even among healthy subjects. Vitamin D, as an environmental factor, is involved in many biological processes, like perception of chronic pain and response to infections. In recent years, evidence has emerged pointing to an involvement of vitamin D in the development of many autoimmune diseases, and a severe vitamin D deficiency has been especially demonstrated in patients affected with autoimmune thyroid disease (AITD). Low levels of vitamin D were found associated with antithyroid antibody presence, abnormal thyroid function, increased thyroid volume, increased TSH levels, and adverse pregnancy outcome in women with AITD. Vitamin D mediates its effect through binding to vitamin D receptor (VDR), which is harbored on many human immune cells, and in this way is able to modulate immune cells activity, triggering both innate and adaptive immune responses. As VDR gene polymorphisms were found to associate with AITD, the evidence links vitamin D deficiency to AITD either through gene polymorphism or by environmental factors (lack of dietary uptake and sun exposure). Vitamin D supplementation may be offered to AITD patients, but further research is needed to define whether it should be introduced in clinical practice.

The mechanisms behind helminth's immunomodulation in autoimmunity.

The incidence of autoimmune diseases has risen throughout the last half a century, mostly in the industrialized world. Helminths and their derivatives were found to have a protective role in autoimmunity and inflammatory conditions, as they manipulate the immune network, attenuating the host's cellular and humoral responses. Indeed, various helminth species used in several human and animal models were shown to limit inflammatory activity in a variety of diseases including inflammatory bowel disease, multiple sclerosis, type 1 diabetes, and rheumatoid arthritis. Our review will focus on the main mechanisms by which helminths and their secreted molecules modulate the host's immune system. The main pathways induce a shift from Th1 to Th2 phenotype, accelerate T regulatory and B regulatory phenotypes, and attenuate the levels of the inflammatory cytokines, leading to a tolerable scenario.