In Vivo and in Vitro Studies of Encapsulated Alpha-1-Antitrypsin and Corticosteroids as Anti-Rheumatic Agents

Abstract

The anti-inflammatory effect of o,-antitrypsin was investigated against rat carrageenan oedema, rat adjuvant arthritis, and rabbit monoarticular arthritis. Anti-inflammatory activity was proved only in rat adjuvant arthritis, and some anti-rheumatic action was evident from the biochemical tests on rabbit synovial fluid. Corticosteroids treatments of rats elevated plasma a,-antitrypsin levels. This effect was dose responsive as were the performed liver function tests of plasma and histological evidence of liver damage. A conclusion whether a,-antitrypsin synthesis was due to a direct action of the steroids on the liver or indirectly due to liver damage could not be made with certainty. The effect of intra-articular administration of a,-antitrypsin and cortisol phosphate in a free and an erythrocyte-encapsulated form was tested on rabbit monoarticular arthritis. o,-Antitrypsin did not prove anti-inflammatory on its own, but a combination of a,-antitrypsin with cortisol phosphate gave superior results to either substance on its own. A method of encapsulation of substances into intact erythrocytes was developed, which leaves the cells with their full circulating lifetime, in contrast to previous preparations. The survival of such preparations was monitored in the circulation of rats, guinea-pigs and rabbits by cell counts after labelling with fluorescein isothiocyanate. Two steroids were encapsulated into erythrocytes at different doses and used as intravenous treatments against adjuvant arthritis in the rat. The encapsulated steroids were superior to the free steroids in controlling the disease. In vitro tests were carried out to investigate the slow release of encapsulated preparations, the biochemistry of the encapsulating agent and the destruction of the preparation by phagocytosis. The concentration of encapsulated materials was assayed.