WEDNESDAY, Feb. 6 (HealthDay News) -- Endogenous opioids such as recently discovered endomorphin-1 (EM-1) and endomorphin-2 (EM-2) exert anti-inflammatory actions in patients with rheumatoid arthritis and osteoarthritis, suggesting these compounds may represent a novel therapeutic option, researchers report in the February issue of Arthritis & Rheumatism.
Rainer H. Straub, M.D., of University Hospital in Regensburg, Germany, and colleagues developed a radioimmunoassay to detect EM-1 and EM-2, and used it to explore patterns of endomorphin expression in patients with rheumatoid arthritis and osteoarthritis. They also studied the effects of endomorphins on human synovial tissue and in a rat model of adjuvant-induced polyarthritis.
The researchers showed that endomorphins were expressed in inflamed tissue in patients with rheumatoid arthritis and osteoarthritis, with macrophages, T cells and fibroblasts staining positive for endomorphins. Synovial concentrations of endomorphin-positive cells were higher in patients with osteoarthritis than rheumatoid arthritis. EM-1 reduced IL-6 secretion in the synovium of rheumatoid arthritis patients and reduced IL-8 secretion in rheumatoid arthritis and osteoarthritis patients. EM-1 treatment reduced inflammation in a rat model of polyarthritis.
"These investigations clearly point toward a possible role of endomorphins as therapeutic agents in rheumatoid arthritis and osteoarthritis," the authors conclude, "especially during acute flares of arthritis due to the large contribution of the nervous system (the neurogenic component of inflammation)."
Abstract
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