Scientists discover control switch for immune system

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Scientists discover control switch for immune system

12/09/2005- Scientists in the US have discovered a cellular switch

that controls immune system function. The research could lead to

future drug treatment advancements for rheumatoid arthritis, multiple

sclerosis and other autoimmune diseases.

By understanding this cellular process for turning off immune system

activity, the hope is that this will lead to new treatments that will

stop unwanted immune responses, such as those which occur in

autoimmune diseases.

In autoimmune diseases, the immune system, which normally wards off

invading viruses and bacteria, instead mistakenly attacks normal body

tissues, leading to illness.

In the study, the team of scientists looked at two members of the

herpes family of viruses, cytomegalovirus and herpes simplex virus,

because of their ability to lay dormant in the immune system without

causing disease.

" These viruses teach us how to manipulate the immune system, " said La

Jolla Institute for Allergy & Immunology (LIAI) scientist Carl Ware.

" We found that these two very different viruses were attacking the

same communication pathway in the immune system. By disrupting that

pathway, the viruses were keeping T lymphocytes - which are white

blood cells that fight disease - from communicating with other cells

in the immune system, " he added.

Central in the viruses' ability to manipulate immune system

communication was a cellular protein called the Herpes virus Entry

Mediator (HVEM), which the scientists found effectively worked as an

" off and on switch " for immune responses.

Several cellular proteins - members of the tumour necrosis factor

(TNF) family - interact with HVEM to enable this immune system

communication switch. HVEM is part of a larger TNF family of

molecules involved in a wide variety of important immune system

functions.

The finding is the latest from Ware's laboratory involving TNF

receptors, which he has been studying for more than 20 years. Drugs

targeted at the TNF family are prominent treatments against some

autoimmune diseases, including rheumatoid arthritis, psoriasis and

Crohn's disease.

Kronenberg, LIAI president and scientific director, said the

scientific community regards the team’s findings as very exciting.

" This research could one day lead to the development of drugs that

mimic the action of HVEM, " he said. " That could give medical science

a new method for reducing or even stopping the inflammation

associated with rheumatoid arthritis and other autoimmune diseases. "

The findings also have implications beyond autoimmune disease,

including possible application in treatments for infectious diseases

and cancer.

" An important part of our findings is that HVEM can not only switch

off immune system response but it can also switch it on, " Ware said.

" This may be valuable in fighting infectious disease, where the body

needs a stronger immune response. It also could aid in prompting

immune cells to attack cancerous cells. "

The findings will be published September 13 in the Proceedings of the

National Academy of Sciences (PNAS) in a paper entitled,

" Evolutionarily Divergent Herpesviruses Modulate T cell activation by

Targeting the Herpesvirus Entry Mediator (HVEM) Cosignaling Pathway. "

http://www.drugresearcher.com/news/printNewsBis.asp?id=62461