Vitamin D in Systemic and Organ-Specific Autoimmune Diseases

Abstract

Lately, vitamin D has been linked with metabolic and immunological processes, which established its role as an essential component of human health preservation. Vitamin D has been defined as natural immune modulators, and upon activation of its receptors (VDRs), it regulates calcium metabolism, cellular growth, proliferation and apoptosis, and other immunological functions. Epidemiological data underline a strong correlation between poor vitamin D status and higher risk for chronic inflammatory illnesses of various etiologies, including autoimmune diseases. Epidemiological, genetic, and basic studies indicated a potential role of vitamin D in the pathogenesis of certain systemic and organ-specific autoimmune diseases. These studies demonstrate correlation between low vitamin D and prevalence of diseases. In addition, VDRs' polymorphisms observed in some of these autoimmune diseases may further support a plausible pathogenic link. Notably, for some autoimmune disease, no correlation with vitamin D levels could be confirmed. Thus, in the current review we present the body of evidence regarding the plausible roles of vitamin D and VDR's polymorphism in the pathogenesis of autoimmunity. We summarize the data regarding systemic (i.e., systemic lupus erythematosus, rheumatoid arthritis, etc.) and organ-specific (i.e., multiple sclerosis, diabetes mellitus, primary biliary cirrhosis, etc.) autoimmune diseases, in which low level of vitamin D was found comparing to healthy subjects. In addition, we discuss the correlations between vitamin D levels and clinical manifestations and/or activity of diseases. In this context, we address the rational for vitamin D supplementation in patients suffering from autoimmune diseases. Further studies addressing the mechanisms by which vitamin D affects autoimmunity and the proper supplementation required are needed.

Low Serum Vitamin D Levels in Egyptian Adults With Chronic Primary Immune Thrombocytopenia: A Single Center Study.

“…5(3), 1789-1797 1790 In patients with ITP, antiplatelet auto-antibodies frequently appear to be directed against GpIb/IX and GPIIb/IIIa expressed on platelets and megakaryocytes [2] Abnormalities of cell-mediated immunity are known to contribute to the pathologic process. Like many other autoimmune diseases, ITP has a T helper cell type 1 bias and a reduced activity of T-regulatory cell [2] Vitamin D, a steroid hormone, which is known to play an essential role in calcium homeostasis, but since the receptor for vitamin D (VDR) is found in cells in almost every tissue, and the enzyme 1-α hydroxylase necessary for the final activation of vitamin D also has a widespread distribution, it appears obvious that vitamin D must have a multitude of function [3] Lower vitamin D levels have been found in several autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, type 1 diabetes mellitus, multiple sclerosis, inflammatory bowel diseases, and, autoimmune gastritis [4] The mechanisms underlying the link between vitamin D with autoimmunity are not completely understood, but probably are associated with its anti-inflammatory and immunomodulatory functions [5] Several studies confirm that vitamin D enhances the innate immune response, whereas it exercises an inhibitory action on the adaptive immune system by inhibiting the proliferation of type 1T helper cells, increasing the quantity of type 2 T helper cells, increasing the quantity of CD4+/CD25+ T-regulator cells, inhibiting B cell proliferation, generation of B memory cells, plasma cell differentiation and immunoglobulin production [6] No currently available studies about vitamin D status in primary ITP patients.…”

A signalome screening approach in the autoinflammatory disease TNF receptor associated periodic syndrome (TRAPS) highlights the anti-inflammatory properties of drugs for repurposing

“…There is good evidence for immunomodulatory activity of vitamin D, and association between poor vitamin D status and increased risk of various autoimmune diseases [56]; evidence also indicates that vitamin D may reduce the risk of severe exacerbations of asthma [57].…”

Association between hypovitaminosis D and systemic sclerosis: True or fake?

“…Vitamin D is considered as a natural modulator and regulator of native and type 1 adaptative immune system [6,31], controlling neutrophils activity and inflammatory response [2]. It has an antifibrotic effect on fibroblasts, consequently inhibitingsynthesis and deposition of extracellular matrix [5].…”

“…Of some importance to report that not all immune disorders are linked to Vitamin D deficiency [6,7].…”