Fibromyalgia is closely associated with widespread pain, disturbance of function, fatigue, depression, irritable bowel syndrome, migraine headaches etc. The exact cause of the condition, however, is not yet known.
There are several studies and hypotheses that point towards immune system abnormalities especially autoimmunity as cause of fibromyalgia.
What is autoimmunity?
Autoimmunity is the term used to describe a condition where the body’s defences target the body’s own cells and tissues failing to make a distinction between self and invading foreign microbes.
Anti-68/48 kD and anti-45 kD
Two autoantibodies, the anti-68/48 kD and the anti-45 kD, have been considered to be the possible markers for certain clinical subtypes of primary fibromyalgia and chronic fatigue syndrome and secondary fibromyalgia/psychiatric disorders respectively.
Of these the anti-68/48 kD antibodies are seen to be closely associated and found in patients with fibromyalgia and chronic fatigue syndrome. These patients typically present with cognitive or mental function disorders as well as increased sleep.
Further there are reports that thyroid autoimmunity could also be associated with fibromyalgia. This association also holds true for rheumatoid arthritis patients.
Patients with fibromyalgia tend to have higher levels of TPO antibodies (antithyroid peroxidase). There is no significant rise of thyroglobulin antibodies (antithyroglobulin).
Presence of thyroid autoimmunity in fibromyalgia has been found to be associated with a concomitant presence of migraine and tension headaches.
Antipolymer antibody levels
Fibromyalgia patients also have slightly higher antipolymer antibody levels than healthy persons. Studies have shown that 30% of fibromyalgia patients are positive for antinuclear antibody and there is 75% preponderance for the speckled pattern.
Studies have shown that fibromyalgia patients have higher serum levels of soluble factors that are released in response to substance P. Normally interleukin-8 promotes sympathetic pain and IL-6 induces fatigue, depression and hyperalgesia or increased pain perception.
Higher levels of IL-10, IL-8 and tumor necrosis factor-alpha were found in fibromyalgia patients than in healthy persons.
Fibromyalgia and systemic lupus erythematosus (SLE)
There is evidence from epidemiological data that 65% of patients with systemic lupus erythematosus (SLE) meet the American College of Rheumatology criteria for fibromyalgia.
Of the SLE patients, 40% had coexistent fibromyalgia that negatively affected their quality of life. Furthermore 57% of patients with rheumatoid arthritis and 24% of those with psoriatic arthritis have concomitant fibromyalgia.
These data reveal an association of fibromyalgia with other autoimmune conditions.