The Link between Your Immune System and Your Back Pain

You know "the neck bone's connected to the back bone," but new studies indicate the "back bone" is also connected to your immune system. Scientists and doctors are making new discoveries every day about how the immune and autoimmune systems are intricately involved in all areas of our health, including our skeletal system and back health.

A new study published in the journal, Arthritis and Rheumatism, says an immune system substance called interleukin-17 (IL-17) may contribute to back pain caused by herniated and degenerated discs.  Researchers compared healthy disc tissue to tissue samples taken from surgical patients with disc disease.  They found IL-17 in 70 percent of patients with degenerated or herniated discs, but rarely found it in healthy disc tissue.

Herniated discs occur when the spine's tough outer cartilage layer cracks and the soft material inside (which the disc is meant to protect) is allowed to protrude.  Previously, doctors thought that pain was caused by irritation to the nerves inside the discs, but this new study indicates that instead, pain might be caused by the immune systems response to inflammation. It suggests that IL-17 may be a mediator for disc degeneration. Mechanical forces may initiate the degenerative process, but biochemical inflammatory changes are involved in disc pathology and pain.

The researchers involved in this study say that the center of the disc is usually not exposed to the immune system until a disc is injured or degenerates. Then the body reacts against the invading inner material just like it would against any virus or foreign body--it launches a response targeted at destroying the foreign substance. The nerve root, which is present near the protruding disc material, reacts by becoming inflamed, damaged and painful.

While this discovery doesn't currently affect treatment plans for back pain caused by disc degeneration, it may eventually lead to new medications that can decrease inflammation and arrest or reverse the disease process.  Previous treatments, like steroid injections, that attempted to target the autoimmune response in the back have been unsuccessful because they didn't target IL-17-specific immune-system mechanisms.  Doctors are optimistic that the IL-17 discovery however, may lead them to develop more specific treatments that target a specific cascade of biochemical responses. 

Researchers are still several steps away from human studies for IL-17 blockers, but every step they've taken so far is one step closer to healing for millions of adults who suffer with back pain.


Arthritis and Rheumatism

Volume 62, Issue 7, pages 1840-1841, July 2010

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