DNA component can stimulate and suppress the immune response

January 27, 2009

A component of DNA that can both stimulate and suppress the immune system, depending on the dosage, may hold hope for treating cancer and infection, Medical College of Georgia researchers say.

Low levels of CpG increase inflammation, part of the body's way of eliminating invaders. But high doses block inflammation by increasing expression of the enzyme indoleamine 2,3 dioxygenase, or IDO, an immunosuppressor, the researchers say.

"The same therapy can have two different effects," says Rusty Johnson, a fifth-year M.D./Ph.D. student in the MCG Schools of Medicine and Graduate Studies. "It was assumed that giving this treatment at higher doses would cause more stimulation, but it has the opposite effect."

The researchers hope that manipulating the dosage can help them optimize the role of inflammation in fighting invaders such as tumors and harmful bacteria. Mr. Johnson presented the findings at the Midwinter Conference of Immunologists this month in Asilomar, Calif. He is working with Drs. Andrew Mellor and David Munn, co-directors of the School of Medicine Immuno Discovery Institute, who discovered IDO's immunosuppressive capabilities more than a decade ago.

With the help of Drs. Babak Baban and Phillip Chandler, scientists in MCG's Immunotherapy Center, they've also learned IDO inhibits inflammation by blocking production of interleukin 6, a secreted factor that causes inflammation.

"This suggests that IDO is a counter-regulatory mechanism that serves as a balance to prevent too much inflammation," Mr. Johnson says. "Too much inflammation leads to destruction of normal body tissue, and this shows IDO's importance in preventing this from occurring."

The researchers already knew that IDO protects tumors from the immune system. While working with collaborators Drs. Alex Muller and George Prendergast at the Lankenau Institute in Philadelphia, they learned its role in tumor formation.

"Without it, a mouse becomes resistant to skin tumor formation, and tumors that do form are smaller and less malignant," Mr. Johnson says.

They've also learned that the cells IDO uses to suppress the immune system - IDO-competent dendritic cells - originate from B cells, which produce antibodies to fight infection.

Source: Medical College of Georgia

Explore further: Exploring how herpes simplex virus changes when passed between family members

Related Stories

Exploring how herpes simplex virus changes when passed between family members

October 22, 2017
A new study explores how herpes simplex virus might change when passed from one individual to another, information that may prove useful in future development of therapeutics and vaccines. This rare glimpse into a transmission ...

Cancer relapse linked to body's own immune system

October 16, 2017
Cancer cells that survive after treatment may use the body's own immune system to wake themselves up and fuel their growth, a new study shows.

How cytoplasmic DNA triggers inflammation in human cells

October 17, 2017
A team led by LMU's Veit Hornung has elucidated the mechanism by which human cells induce inflammation upon detection of cytoplasmic DNA. Notably, the signal network involved differs from that used in the same context in ...

Mutant gene found to fuel cancer-promoting effects of inflammation

October 19, 2017
A human gene called p53, which is commonly known as the "guardian of the genome," is widely known to combat the formation and progression of tumors. Yet, mutant forms of p53 have been linked to more cases of human cancer ...

Inflammation trains the skin to heal faster

October 18, 2017
Scars may fade, but the skin remembers. New research from The Rockefeller University reveals that wounds or other harmful, inflammation-provoking experiences impart long-lasting memories to stem cells residing in the skin, ...

Chronic inflammation plays critical role in sustained delivery of new muscular dystrophy therapy

October 16, 2017
Macrophages, a type of white blood cell involved in inflammation, readily take up a newly approved medication for Duchenne muscular dystrophy (DMD) and promote its sustained delivery to regenerating muscle fibers long after ...

Recommended for you

Engineered protein treatment found to reduce obesity in mice, rats and primates

October 19, 2017
(Medical Xpress)—A team of researchers with pharmaceutical company Amgen Inc. report that an engineered version of a protein naturally found in the body caused test mice, rats and cynomolgus monkeys to lose weight. In their ...

New procedure enables cultivation of human brain sections in the petri dish

October 19, 2017
Researchers at the University of Tübingen have become the first to keep human brain tissue alive outside the body for several weeks. The researchers, headed by Dr. Niklas Schwarz, Dr. Henner Koch and Dr. Thomas Wuttke at ...

Cancer drug found to offer promising results in treating sepsis in test mice

October 19, 2017
(Medical Xpress)—A combined team of researchers from China and the U.S. has found that a drug commonly used to treat lung cancer in humans offers a degree of protection against sepsis in test mice. In their paper published ...

Tracing cell death pathway points to drug targets for brain damage, kidney injury, asthma

October 19, 2017
University of Pittsburgh scientists are unlocking the complexities of a recently discovered cell death process that plays a key role in health and disease, and new findings link their discovery to asthma, kidney injury and ...

Study reveals key molecular link in major cell growth pathway

October 19, 2017
A team of scientists led by Whitehead Institute has uncovered a surprising molecular link that connects how cells regulate growth with how they sense and make available the nutrients required for growth. Their work, which ...

Large variety of microbial communities found to live along female reproductive tract

October 18, 2017
(Medical Xpress)—A large team of researchers from China (and one each from Norway and Denmark) has found that the female reproductive tract is host to a far richer microbial community than has been thought. In their paper ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.