Evaluation of the possible therapeutic role of omega-3 on ankle joint and lung in a model of rheumatoid arthritis in rats: A histological and immunohistochemical study

Introduction: Rheumatoid arthritis (RA) is a chronic inflammatory systemic autoimmune disease. Lung disease has beenrecognized as a common complication of RA. Omega-3 is an essential fatty acid with wide range of activity.Aim of the work: To investigate the possible therapeutic role of omega-3 free fatty acid on the structure of ankle joint andlung in a model of adjuvant-induced RA in rats.Materials and Methods: Thirty adult male albino rats were divided into three groups; Group I served as a control group.Group II was used as a model of RA. Rats of this group were given single subcutaneous injection of 0.1ml of completeFreund adjuvant in their hind paws. Group III (omega 3-treated group), omega-3 was given in as a dose of 300 mg/kg orallyadministered after two weeks of RA induction and continued daily for another two weeks. The ankle joint and the lungs fromall groups were dissected out after two and four weeks and processed for light microscopic examination. Histomorphometricstudies and statistical analysis were also done.Results: RA was confirmed histologically in the ankle joint after two weeks and was aggravated after four weeks. Erosionof articular cartilage and mononuclear cellular infiltration in the synovium were noticed in both time points. Moreover, thelungs after two weeks showed focal inflammatory cellular infiltration and pulmonary fibrosis that were more evident afterfour weeks of untreated RA. This was associated with significant increase in the mean area percentage of collagen fibers andnumber of cells positive for TNF-α immunohistochemical reaction compared to the control group. Omega-3 treated groupillustrated improvement of both ankle and lung structures.Conclusion: Omega-3 significantly ameliorated the structural damage of ankle joint and lung after RA induction.