Cortisone-type injections into joints control painful rheumatoid arthritis by blocking protein changes that damage joints (Arthritis Research & Therapy, published online Feb. 2012).
REACTIONS THAT CAUSE RHEUMATOID ARTHRITIS: Rheumatoid arthritis (RA) is characterized by the production of PAD enzymes that convert an amino acid, arginine, into citrullinated proteins. Then the victim's immunity makes highly specific anti- citrullinated protein antibodies that attack the synovium and cause it to swell, thicken, and hurt.
WHY CORTISONE INJECTIONS WORK: Injecting cortisone-type drugs into the joints blocks the production of the PAD enzymes that produce citrullinated proteins, and this decreases the thickness of the synovium, and the resultant pain.
THE STUDY: The authors biopsied the swollen knees of patients with rheumatoid arthritis and normal controls. One group was given methotrexate, a common RA treatment used for more than 40 years. The other group was given cortisone-type injections (40 mg triamcinolone hexacetonide) into the knee joint.
Antibodies to citrullinated proteins were found in 86 percent of biopsy samples from the RA patients and in none of the healthy tissue samples. After eight weeks, those receiving the cortisone- type injections had far less swelling of their synovia, far less evidence of inflammation under the microscope, and lower levels of cutrullinated proteins and PAD enzymes. Methotrexate had no effect on citrullinated proteins, PAD enzymes or inflammation in the synovium, although these patients did feel better.
CONCLUSION: This study explains why cortisone-type injections are such an effective treatment for rheumatoid arthritis. However, the effects of the injections do not last and a few months later, the patient may need another injection that may increase risk for diabetes, osteoporosis, and other side effects.