Are Galectins a New Target for Reducing Arthritic Joint Pain?
Pain is the most common complaint of arthritis sufferers and the primary reason they seek medical treatment. Pain so dominates the experience of arthritis sufferers that many physicians believe that pain control should be the primary goal of medical interventions. Most of this pain arises from inflammation of the joints.
Inflammation is a normal process by which the body gets rid of bad bacteria and repairs the damage caused by physical injuries. The immune cells are essential components of this process and therefore need to be recruited to infected and damaged areas to perform their function. In arthritis patients, immune cells are being recruited to worn or damaged joints. This causes inflammation, but rather than helping to repair the joint, the inflammation become chronic and causes more damage.
Stefan Tögel at the University of Vienna, together with a team of researchers, has discovered that a protein is expressed at above normal levels in the joints of osteoarthritis patients.This type of protein, called galectins, functions to hold joint tissue together in healthy people. Galectins also play a role in the immune system by creating a physical attachment between bacteria and immune cells, thereby helping the immune cells consume and destroy the bacteria.
In healthy joints, galectins are expressed at low level and help to form attachments between joint cells and tissue. What Tögel and his research team showed was that if the joint becomes worn or damaged, galectins are expressed at higher than normal levels. In addition, the more damaged and worn a joint was, the more galactin the joint tissue produced.
In the absence of an infectious agent like bacteria, the excess levels of galectin would tend to bind indiscriminately to the damaged joint tissue. The damaged joint tissue in arthritis patients is therefore becoming coated with galectins with nothing else to bind to except immune cells.
From the perspective of the immune cells, the damaged joint tissue looks like a bad bacteria and begins to consume and destroy it. In addition, other immune cells are recruited to the damaged joint because the immune system ‘thinks’ it is infected Since the joint tissue isn’t infected and cannot be repaired, the immune cells become permanent residents and the inflammatory process becomes chronic.
The discovery of galectins and the possible role these proteins play in chronic joint inflammation is exciting news because it may provide a new way to treat chronic inflammation and the pain it causes.
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