Linköping [Sweden]March 9 (ANI): The biological function of C-reactive protein (CRP) has long been unknown. Researchers at Linköping University in Sweden have discovered that this protein is beneficial in the inflammatory disease systemic lupus erythematosus or SLE. According to the study published in the Journal of Autoimmunity, this is only valid for one of CRP’s two forms.
Most of us have taken a CRP blood test on more than one occasion. This is a very common routine test used to detect infection or systemic inflammation in the body. What is measured is the level of C-reactive protein or CRP for short.
“CRP is an ancient protein and similar proteins are found in all animals, even in primitive organisms. When a protein has been so well conserved throughout evolution, it usually means that it has an important function. CRP is widely used in clinical care. as a marker for ongoing inflammation, but few have studied its biological effects, says Christopher Sjowall, senior associate professor at the Department of Biomedical and Clinical Sciences, BKV, at Linköping University, LiU, and consultant at the Reumatologiska Kliniken (rheumatology clinic) in Östergötland.
Christopher Sjowall has for many years researched the chronic inflammatory disease systemic lupus erythematosus, SLE. Somewhat simplified, it is a disease where the body’s immune system begins to react to its own body, i.e. an autoimmune disease. One such reaction is the formation of antibodies, called autoantibodies, which target endogenous components. However, in cases of SLE, when the inflammatory activity in the body is high, SLE patients have a lower than expected CRP level. Previous studies in animals with the lupus-prone disease have shown that addition of CRP can result in milder disease and lower autoantibody levels, suggesting that CRP may also have a beneficial function in human SLE, although the reason for this has not been clarified.
One of the key players in SLE is a signaling protein called type I interferon. Interferon is normally a very important component of the body’s defense against infections. Interferon levels increase rapidly in the first hours after infection and slow it down by, for example, making it harder for viruses to grow. Interferon levels should drop after a while. But in some diseases, like SLE, the interferon stays in the system too long and causes damage.
“We have shown a mechanism that is likely to be quite important, where the relative lack of CRP in SLE patients with high disease activity leads to high interferon activity,” says Christopher Sjowall.
In their study, the researchers investigated the impact on interferon and other signaling proteins caused by CRP- and SLE-specific immune complexes formed by autoantibodies that have reacted with material from dead cells. One thing they studied was what happened when serum from SLE patients with varying levels of CRP was added to healthy cells. They found that there was more interferon when CRP levels were low compared to when they were high, which they interpret as CRP helping to reduce the interferon response.
It also turned out that the shape of the CRP is important, something that the Linköping researchers were the first to show. The protein consists of five identical units (pentamer form), which can be divided and function independently (monomer form). And the researchers found that it is only the pentameric form of CRP that reduces interferon activity.
“The finding that the pentamer form of CRP can suppress the immune response is also interesting in connection with other diseases, such as various viral diseases,” says Marie Larsson, professor of virology at BKV at LiU and one of the other researchers behind the study.
These findings open up research into drugs to reduce immune complexes and elevated interferon levels. However, since interferon plays a key role in the body’s defense against infections, the treatment of SLE and similar diseases is a constant balancing act and further research is needed to find optimal treatment strategies. (ANI)
Source: sn.dk