Rheumatoid arthritis is a chronic inflammatory disease characterized by overproduction of inflammatory mediators along with undermined oxidative defensive mechanisms.
Pathological angiogenesis was found to play a critical role in the progression of this disease. The current study was carried out to evaluate the anti-angiogenic, anti-inflammatory, and
anti-oxidant effects of
evening primrose oil (EPO), rich in
gamma linolenic acid (GLA), either alone or in combination with
aspirin or
celecoxib, on adjuvant-induced
arthritis.
Arthritis was induced by
subcutaneous injection of complete
Freund's adjuvant (CFA) in the right hind paw of male albino rats. All treatments were administered orally from day 0 (EPO, 5 g/kg b.w.) or day 4 (
celecoxib, 5 mg/kg;
aspirin, 150 mg/kg) till day 27 after CFA injection. In the arthritic group, the results revealed significant decrease in the
body weight and increase in ankle circumference, plasma
angiopoietin-1 (ANG-1) and
tumor necrosis factor-alpha (TNF-α) levels.
Anti-oxidant status was suppressed as manifested by significant decline in
reduced glutathione content along with decreased enzymatic activity of
superoxide dismutase and increased lipid peroxidation.
Oral administration of EPO exerted normalization of
body weight, ANG-1, and TNF-α levels with restoration of activity as shown by reduced
malondialdehyde levels. Moreover, histopathological examination demonstrated that EPO significantly reduced the synovial
hyperplasia and inflammatory cells invasion in joint tissues, an effect that was enhanced by combination with
aspirin or
celecoxib. The joint use of GLA-rich natural
oils, which possess anti-angiogenic, anti-inflammatory, and
anti-oxidant activities, with traditional
analgesics represents a promising strategy to restrain the progression of
rheumatoid arthritis.