Vitamin D Activates Two Key Immune Systems

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Vitamin D Activates Two Key Immune Systems

 

Landmark findings show why the " sunshine-and-seafood " vitamin is

increasingly seen as critical to defense against infection

 

by Craig Weatherby

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New findings from Denmark affirm and expand the role that vitamin D

plays in our bodies most sophisticated immune response to infectious

agents. And they follow an important discovery reported last year from

Oregon State University (OSU), which confirmed vitamin Ds essentiality

to humans first-line immune response to disease microbes. Lets take a

look at both of these closely related studies, starting with last years

OSU investigation. Vitamin Ds role in the first-line defense against

disease microbesThe human body responds to disease-causing microbes

bacteria, viruses, and other pathogens by using two distinct but partly

overlapping aspects of its immune system. Key Points

- Gene study affirms and details vitamin Ds key role in the bodys

sophisticated adaptive immune system, which remembers and targets

specific pathogens.

- Findings follow affirmation of vitamin Ds role in activating

anti-microbial proteins of the less targeted but still essential innate

immune system.

- Immune system proteins activated by vitamin D also play key roles in

cell and blood vessel growth, wound healing, and in the skin and

digestive organs.

  The innate immune system is first line of defense against

bacteria, viruses and other pathogens. It is ancient in evolutionary

terms, dating back some 60 million years to our pre-human primate

ancestors. (The more recently evolved adaptive immune system which was

the subject of the new vitamin D findings from Denmark reacts to and

remembers specific microbes to provide a more targeted, potentially more

effective defense.) The innate immune system which employs proteins

called consists of proteins call anti-microbial peptides recognizes that

something that probably doesnt belong in the body, even though the

specific pathogen may never have been encountered before. Last August,

researchers from OSU reported their discovery that the ability of

vitamin D to regulate the innate immune systems anti-microbial peptides

is so important that is has been conserved through almost 60 million

years of evolution (Gombart AF, Saito T, Koeffler HP 2009). The Oregon

team also noted that the vitamin D-regulated innate immune system is

unique to primates, including humans, and occurs in no other known

animal species. They believe that this vitamin-D-mediated immune

response must be critical to primates survival, or it would not have

been retained through millions of years of natural selection. Last year,

the Oregon team found a new genetic element that allows vitamin D to

boost the innate immune response by activating antimicrobial peptides.

And if the peptides suppress a pathogen effectively, this may help

prevent the adaptive immune system from overreacting. (It had already

been known that vitamin D prevents the adaptive immune system from

overreacting, thereby reducing counterproductive inflammation.) As OSU

professor Adrian Gombart said last August, It's essential that we have

both an innate immune response that provides an immediate front line of

defense [and] protection against an overreaction by the immune system,

which is what you see in sepsis and some autoimmune or degenerative

diseases. This is a very delicate balancing act, and without sufficient

levels of vitamin D you may not have an optimal response with either

aspect of the immune system. (OSU 2009) He described the history and

importance of vitamin D in innate immunity in a 2009 review article

thats worth quoting at length: Vitamin D deficiency has been correlated

with increased rates of infection. Since the early 19th century, both

environmental (i.e., sunlight) and dietary sources (cod liver) of

vitamin D have been identified as treatments for TB. The recent

discovery that vitamin D induces antimicrobial peptide gene expression

explains, in part, the antibiotic effect of vitamin D and has greatly

renewed interest in the ability of vitamin D to improve immune function.

Subsequent work indicates that this regulation is biologically important

for the response of the innate immune system to wounds and infection and

that deficiency may lead to suboptimal responses toward bacterial and

viral infections. (Gombart A

2009) And as Dr. Gobart explained in a press release, the anti-microbial

peptide activated by vitamin D plays other key roles in human health:The

[vitamin D-activated] antimicrobial peptide that we're studying seems to

be involved not just in killing bacteria It recruits other immune cells

and sounds the alarm that something is wrong. It helps promote

development of blood vessels, cell growth and healing of wounds. And it

seems to have important roles in barrier tissues such as skin and the

digestive system. (OSU 2009) Now, lets turn our attention to the new

study from Denmark, which concerns vitamin Ds role in the more

sophisticated, powerful and potentially self-destructive adaptive immune

system. New genome study details vitamin Ds key part in the modern

immune systemDanish scientists say theyve discovered that vitamin D is

crucial to activating the adaptive immune system, which evolved later

than the innate immune system. Their study focused on the T cells of the

adaptive immune system, which, to be effective, must first be triggered

to transform into killer or helper cells Killer T cells seek out and

destroy pathogens, while helper T cells remember the pathogen so that

the body will mount a more efficient immune response should it reappear

in the future. The Danes landmark study demonstrates that T cells rely

on vitamin D to activate and remain dormant if vitamin D is lacking in

the blood. According to lead author Carsten Geisler, Ph.D., We have

discovered that the first stage in the activation of a T cell involves

vitamin D. When a T cell is exposed to a pathogen, the contact initiates

a biochemical reaction that prompts the cell to extends the signaling

device or antenna' known as a vitamin D receptor Unless a T cells

receptor encounters vitamin D, its full transformation into an effective

killer or helper cell will cease and this is why the Danes achievement

constitutes a major breakthrough. As Dr. Geisler said, Scientists have

known for a long time that vitamin D is important for calcium absorption

and the vitamin has also been implicated in diseases such as cancer and

multiple sclerosis, but what we didn't realize is how crucial vitamin D

is for actually activating the immune system - which we know now. Danish

findings hold practical implicationsThe Danes say that they believe

their discovery may help doctors enhance patients immune responses and

deal with autoimmune diseases and reduce rejection of transplanted

organs. Active T cells multiply at an explosive rate and can create

runaway inflammation with serious, and sometimes as in the state of

sepsis that can follow a major infection even fatal consequences. And

after an organ transplant, T cells may attack the donor organ as a

foreign invader. In an autoimmune disease such as rheumatoid arthritis

or lupus, T cells mistake fragments of the body's own cells for foreign

pathogens, leading them to attack the bodys own tissues. The Danish team

was able to track the steps by which an inactive T cell changes into an

active cell a breakthrough that may allow doctors to intervene at

several points to influence the bodys immune response. The findings,

said Professor Geisler, could help us to combat infectious diseases and

global epidemics. They will be of particular use when developing new

vaccines, which work precisely on the basis of both training our immune

systems to react and suppressing the body's natural defenses in

situations where this is important as is the case with organ transplants

and autoimmune disease. Most vitamin D is produced when UV sunrays

strike the skin. The only good dietary sources are supplements and

certain foods: especially fatty fish such as salmon, tuna, sardines,

sablefish, and mackerel. Sources

- Adams JS, Ren S, Liu PT, Chun RF, Lagishetty V, Gombart AF, Borregaard

N, Modlin RL, Hewison M. Vitamin D-directed rheostatic regulation of

monocyte antibacterial responses. J Immunol. 2009 Apr 1;182(7):4289-95.

- Copenhagen University (CU). Vitamin D crucial to activating immune

defenses. March 3, 2010. Accessed at

http://www.imakenews.com/eletra/go.cfm?z=vitalchoiceseafood%2C428961%2Cb1kJkvww%\

2C3849958%2CbgGlHGh

- Gombart AF, Bhan I, Borregaard N, Tamez H, Camargo CA Jr, Koeffler HP,

Thadhani R. Low plasma level of cathelicidin antimicrobial peptide

(hCAP18) predicts increased infectious disease mortality in patients

undergoing hemodialysis. Clin Infect Dis. 2009 Feb 15;48(4):418-24.

- Gombart AF, Saito T, Koeffler HP. Exaptation of an ancient Alu short

interspersed element provides a highly conserved vitamin D-mediated

innate immune response in humans and primates. BMC Genomics. 2009 Jul

16;10:321.

- Gombart AF. The vitamin D-antimicrobial peptide pathway and its role

in protection against infection. Future Microbiol. 2009 Nov;4:1151-65.

Review.

- Marina Rode von Essen, Martin Kongsbak, Peter Schjerling, Klaus

Olgaard, Niels dum & Carsten Geisler. Vitamin D controls T cell antigen

receptor signaling and activation of human T cells. Published online:

March 7, 2010 / doi:10.1038/ni.1851

- Oregon State University (OSU). Key feature of immune system survived

in humans, other primates for 60 million years. August 18, 2009.

Accessed at

http://www.imakenews.com/eletra/go.cfm?z=vitalchoiceseafood%2C428961%2Cb1kJkvww%\

2C3849959%2CbgGlHGh