An Update on the Effects of Vitamin D on the Immune System and Autoimmune Diseases

Abstract

Vitamin D intervenes in calcium and phosphate metabolism and bone homeostasis. Experimental studies have shown that 1,25-dihydroxyvitamin D (calcitriol) generates immunologic activities on the innate and adaptive immune system and endothelial membrane stability. Low levels of serum 25-hydroxyvitamin D (25(OH)D) are associated with an increased risk of developing immune-related diseases such as psoriasis, type 1 diabetes, multiple sclerosis, and autoimmune diseases. Various clinical trials describe the efficacy of supplementation of vitamin D and its metabolites for treating these diseases that result in variable outcomes. Different disease outcomes are observed in treatment with vitamin D as high inter-individual difference is present with complex gene expression in human peripheral blood mononuclear cells. However, it is still not fully known what level of serum 25(OH)D is needed. The current recommendation is to increase vitamin D intake and have enough sunlight exposure to have serum 25(OH)D at a level of 30 ng/mL (75 nmol/L) and better at 40–60 ng/mL (100–150 nmol/L) to obtain the optimal health benefits of vitamin D.

The Association between Serum Vitamin D Concentration and New Inflammatory Biomarkers—Systemic Inflammatory Index (SII) and Systemic Inflammatory Response (SIRI)—In Patients with Ischemic Heart Disease

“…It also modulates the adaptive response of Treg and Th2 lymphocytes through VDR activation and leads to their activation and increased production of anti-inflammatory cytokines [ 97 , 98 ]. Calcitriol decreases the production of pro-inflammatory cytokines by T1 lymphocytes [ 99 , 100 ], blocks the maturation of B lymphocytes and their transformation into effector B cells, and decreases their expression of MHC-II [ 101 , 102 ]. Furthermore, it has an immunosuppressive effect via the NFκB transcription factor [ 103 ].…”

The Association between Standardized Serum 25-Hydroxyvitamin D Concentration and Risk of Anemia: A Population-Based Cross-Sectional Study

“…Our subgroup analysis also suggested significant interactions of anemia [31,32]. Further, low levels of 25(OH)D may increase the risk of immune-related diseases because they exert an immunomodulatory effect through nuclear vitamin D receptor expressed by antigen-presenting cells and activated T and B cells [33,34]. erefore, we screened the database for data from patients with immune diseases and hyperparathyroidism; after adjusting for these covariates, the results were generally consistent with those above, confirming that arthritis and rheumatism are not additional risk factors for reduced plasma 25(OH)D concentrations [35].…”

Causal Associations between Vitamin D Levels and Psoriasis, Atopic Dermatitis, and Vitiligo: A Bidirectional Two-Sample Mendelian Randomization Analysis

“…Early epidemiological studies have shown lower serum vitamin D levels in patients with psoriasis than healthy controls [12]. Administrating vitamin D supplementation led to reduced mortality in patients with psoriasis [17] and topical vitamin D analogues demonstrated effectiveness in treating psoriasis [9]. A recent prospective study suggested that low 25(OH)D level was associated with high risk of psoriasis using both cox proportional hazard model and MR analysis [27].…”

“…In addition, C3-epimer of 25(OH)D 3 (C3-epi-25(OH)D 3 ), a vitamin D metabolite from 25(OH)D 3 through 3β to 3α isomerization transformation, can also affect the amount of bioactive vitamin D conversion [7]. Recent studies have shown that 25(OH)D and its relevant compounds are associated with many diseases, including cancers, kidney, infectious, and autoimmune diseases [8,9]. These findings suggest that vitamin D might play a role in calcium homeostasis, immune regulation, anti-bacterial, and anti-inflammation.…”