Immune function refers to the body’s natural defense to pathogens. Whereas autoimmune is the condition where the body’s immune cells attacks own body’s tissue in some situations. And that results in inflammation, tissue damage, and loss of function of the affected organs or joints. For example, if immune cells target joints it develops Rheumatoid arthritis, it targets the intestine it develops Crohn’s disease or Ulcerative colitis, if targets thyroid gland you can develop Hashimoto’s thyroiditis or Graves’ disease, if damage nervous system you can develop Multiple Sclerosis, if damage respiratory they develop Asthma if damages pancreatic β-cells develops type 1 diabetes and many others. So autoimmunity is a major concern in the modern lifestyle. Apart from calcium circulation vitamin D hormone also plays many other important roles including gene expression. Is there any impact of vitamin D in immune function and autoimmune disease have a look.
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Vitamin D and Immune Functions
We have two different immune systems as innate and adoptive to fight against pathogens. The Innate system has a presence at all times, reacts immediately and generally, activates the adaptive system and does not improve with repeated exposure. The components within the innate system include macrophages, dendritic cells, myeloid cells, and some others as well as signaling protein cells. The Adaptive system develops in response to infection, gives protection against specific pathogens, leverages components of the innate response as well as develops memory against pathogens. The components within the adaptive system include T and B cells, antibodies and signaling protein. While the innate immune system acts with immediate response adaptive immune system acts for the long term.

Impact of vitamin D in immune function and autoimmune disease
VDR or Vitamin D Receptor
Vitamin D binds with Vitamin D Receptor and thus exert its many actions. The perception of vitamin D has been changed after the discovery of VDR or Vitamin D Receptor expression in almost all human cells. 1,25(OH)2D3 or active form of vitamin D initiates its signaling cascade by binding to the vitamin D receptor (VDR), which is a nuclear receptor that acts as a transcription factor. Activation of VDR induces a wide variety of so-called non-classic effects, with modulation of cellular growth, proliferation, apoptosis, and immune cell activation. That has further increased the attention for the extraskeletal effects of vitamin D. Vitamin D deficiency has now been linked to not only bone health but also, for example, cancer, cardiovascular diseases, and autoimmune diseases. (1,2)
Immune Function
After the discovery of VDR in white blood cells of the body’s defense system numerous studies have investigated the link between vitamin D and the incidence and severity of autoimmune diseases.
Various immune cells, including monocytes, dendritic cells, macrophages, B cells, and T cells, also have the capability to convert inactive vitamin D into 1,25(OH)2D3 or vitamin D active form. This allows for local regulation of the concentration of 1,25(OH)2D3 at the site of inflammation and illustrates an important role for the cells of the immune system in the systemic effects of vitamin D. Hence it modulates both innate as well as adaptive immune responses. While vitamin D plays a significant role in enhancing the innate immune response but exerts control of the adaptive immune system. Hence these data indicate that active vitamin D or 1,25(OH)2D3 plays a role in maintaining the equilibrium of the immune system. (1,3, 7)
In several inflammatory diseases, researchers found an association of vitamin D supplementation with reduced levels of C-reactive protein, and inflammation as well as erythrocyte sedimentation rate. In study researchers observed low vitamin D as common in ICU patients. They also found longer survival times among vitamin D sufficient patients. (4)
Also read how to build and educate your immune system naturally.
Vitamin D against bacterial infection
Vitamin D helps in producing as well as regulating antimicrobial chemical particularly cathelicidin antimicrobial peptide(CAMP) in the body. CAMP acts as an antibiotic but without side effects. It has a critical role in mammalian innate immune defense against invasive bacterial infection. And the vitamin D receptor has control over the cathelicidin gene and thus protects against bacterial infection. (5)
In a 2019 Meta-analysis as published in the European Respiratory Journal pooled data from 1,850 TB patients who took part in clinical trials of vitamin D in eight countries. The study also found vitamin D helps to boost the immune system to speed up the clearance of tuberculosis (TB) bacteria from the lungs of people with multi-drug resistant TB. (6)
Vitamin D and Diabetes
Type 1 diabetes is an autoimmune disease with impairment of pancreatic cells to produce insulin. We have already discussed the role of vitamin D in type 1 as well as type 2 diabetes.
Multiple sclerosis and Vitamin D
In Multiple Sclerosis, the body’s immune system attacks and impairs the central nervous system. T cells apart from the adaptive immune system play a crucial role in fighting against infections in healthy people but in autoimmune disease, the same T cells attack the body’s own tissue. Vitamin D deficiency is associated with an increased risk of Multiple Sclerosis. (7)
In a recent 2019 published study, the research team from the University of Edinburgh focused on how vitamin D affects a mechanism in the body’s immune system– dendritic cells’ ability to activate T cells. Dendritic cells (DC), a specialized sentinel or antigen-presenting cells that bridge the innate and adaptive immune response. And thus it plays a crucial role in shaping the adaptive immune response. Vitamin D also influences the development of dendritic cells.
CD31 acts as a key coinhibitory receptor molecule in the development of dendritic cells. It prevents effective T cell priming at least in part by reducing the interaction time between dendritic cells and T cells. The active vitamin D can enhance CD31 expression in both mice as well as human dendritic cells. And thus involves in regulation of immune reaction. This might explain why people with vitamin D deficiency may be more susceptible to diseases such as multiple sclerosis. (8, 9)
Systemic lupus erythematosus
The systemic lupus erythematosus (SLE) can cause chronic inflammation and damage in multiple tissues and organs It can affect the skin, joints, kidneys, brain, and other organs. Development of SLE may be linked to genetic, environmental, hormonal and certain medications. As the majority of the patients are sensitive for sunlight so protecting them from sunlight can result in vitamin D deficiency. (1,10) Science vitamin D has immunomodulatory effect and individuals with SLE tend to develop vitamin D deficiency, vitamin D supplementation may help here. However, due to too many confounding factors further large scale studies are needed.
Some other autoimmune diseases
Vitamin D may also have links with some other autoimmune diseases like Rheumatoid Arthritis, Crohn’s Disease. (1)However, requires more results. Research also suggested a beneficial role of vitamin D in the management of thyroid disease including Hashimoto’s thyroiditis, Graves’ disease. (11) Data also suggest that vitamin D insufficiency or deficiency may be associated with an increased risk of thyroid autoimmunity. (12)
Bottom Line:
As vitamin D hormone has the immunomodulatory effect it has roles in immune function as well as autoimmunity. Also, deficiency of vitamin D is observed in numbers of autoimmune diseases. And also supplementation had shown improvement in conditions in many cases. Hence maintaining vitamin D level is a healthier choice in modern life under shade. Earlier we mentioned that why it is wiser to have vitamin D along with vitamin K2. Other mineral goes well includes calcium, magnesium, zinc. And it is also important to know that autoimmune disease can be triggered by multiple factors. Such factors include gut health, chronic stress and hormonal imbalance, toxins from the environment or medicinal or foods, foods as well as infections.
For vitamin D dose, safety, best form, read how vitamin D deficiency is linked with chronic fatigue and body aches
Disclaimer: Information provided here are generalized information for educational purpose only, not intended to provide one to one health consultation or replace practice of a qualified practitioner. Different people may have different health condition and may have different reaction to the same food. Hence it has been advised to consult with health care provider before application of any of above guidelines. Source and References: 1. Wendy Dankers, Edgar M. Colin, Jan Piet van Hamburg, and Erik Lubberts, Vitamin D in Autoimmunity: Molecular Mechanisms and Therapeutic Potential,Front Immunol. 2016; 7: 697 2. Peelen E, Knippenberg S, Muris AH, et al. Effects of vitamin D on the peripheral adaptive immune system: a review. Autoimmun Rev 2011; 10: 733-43 3.Baeke F, Takiishi T, Korf H, Gysemans C, Mathieu C., Vitamin D: modulator of the immune system, Curr Opin Pharmacol. 2010 Aug;10(4):482-96 4.Y. Arnson,I. Gringauz,D. Itzhaky,H. Amital,Vitamin D deficiency is associated with poor outcomes and increased mortality in severely ill patients, Q J Med 2012;105:633–639 5.Adrian F Gombart,The vitamin D–antimicrobial peptide pathway and its role in protection against infection,Future Microbiol. 2009 Nov; 4: 1151. 6.David A. Jolliffe, Davaasambuu Ganmaa, Christian Wejse, Rubhana Raqib,Md. Ahsanul Haq, Nawal Salahuddin, Peter K. Daley, Anna P. Ralph, Thomas R. Ziegler, Adrian R. Martineau,Adjunctive vitamin D in tuberculosis treatment: meta-analysis of individual participant data,European Respiratory Journal 2019 7.Barbara Prietl, Gerlies Treiber, Thomas R. Pieber, and Karin Amrein,Vitamin D and Immune Function,Nutrients. 2013 Jul; 5(7): 2502–2521 8.Clement M, Fornasa G, Guedj K, Ben Mkaddem S, Gaston AT, Khallou-Laschet J, Morvan M, Nicoletti A, Caligiuri G.,CD31 is a key coinhibitory receptor in the development of immunogenic dendritic cells, Proc Natl Acad Sci U S A. 2014 Mar 25;111(12):E1101-10 9.Louise Saulet. al.,1,25-Dihydroxyvitamin D3 Restrains CD4+ T Cell Priming Ability of CD11c+ Dendritic Cells by Upregulating Expression of CD31, Front. Immunol., 28 March 2019 10.https://medlineplus.gov/ency/article/000435.htm 11.Dohee Kim,The Role of Vitamin D in Thyroid Diseases,Int J Mol Sci. 2017 Sep; 18(9): 1949 12.Immacolata Cristina Nettore, Luigi Albano, Paola Ungaro, Annamaria Colao, and Paolo Emidio Macchia,Sunshine vitamin and thyroid,Rev Endocr Metab Disord. 2017; 18(3): 347–354

2 Responses
Vitamin D seems to have a lot beneficial effect. Exposure to sun light promotes Vitamin D synthesis. Unfortunately our tendency to protect ourselves from sunlight is resulting in reduced synthesis of Vitamin D and many associated diseases are seeing an increase. Although a direct casualty is yet to be demonstrated, in nature small contribution by many factors bring about a holistic effect on a living system.
Thank you, I’ve recently been looking for info about this topic for ages and yours is the best I have discovered so far. But, what about the bottom line? Are you sure about the source?