RESUMO
Rheumatoid arthritis [RA] is an autoimmune disease that leads to chronic inflammation in the joints with subsequent cartilage and bone destruction. RA induces a massive burden on health services worldwide. This study was designed to evaluate the possible therapeutic effect of 'Chaetomium globosum' extract in the treatment of RA in a rat model. Forty male Wistar albino rats aged 8-10 weeks were divided into four groups of 10 rats each. The control group [group I] was injected subcutaneously with 0.1 ml of saline. RA was induced in the other three groups [groups II, III, and IV] by single subcutaneous injection of 0.1 ml of complete Freund's adjuvant in the footpad of the right hind paw. Group II was induced with arthritis and left untreated. Rats in groups III and IV were treated by administering either C. globosum 10 micro g/kg or methotrexate [MTX] 0.3 mg/kg subcutaneously twice weekly for 2 weeks from day 12 after induction of arthritis. Animals of all groups were sacrificed on day 28 from the start of the experiment. The ankle joints were processed and stained with H and E, Masson's trichrome, and immunohistochemical stain for inducible nitric oxide synthase. Specimens were also processed for transmission electron microscopic study. Untreated arthritic rats revealed paw swelling, synovial hyperplasia, inflammatory infiltration, collagen accumulation, cartilage degradation, bone destruction, and significant increase in inducible nitric oxide synthase-positive chondrocytes. Transmission electron microscopic examination confirmed these results. The present study demonstrated for the first time that C. globosum significantly reduced all the clinical and histopathological changes of arthritis similar to MTX. C. globosum extract had therapeutic effects similar to the well-established drug MTX and could be devoid of its serious side effects.