Effectiveness of rituximab treatment in Bleomycin-induced experimental scleroderma

Scleroderma is a chronic inflammatory disease characterized by vascular injury, immunological abnormalities and widespread fibrosis of skin and internal organs. Rituximab is a chimeric monoclonal antibody against CD20 antigen of B lymphocytes and causes the depletion of B cells. Rituximab is also used in the treatment of several autoimmune diseases at the present dayThe aim of this study was to evaluate the preventive efficacy of rituximab on bleomycin-induced experimental scleroderma model.This study involved 4 groups Balb/c mice (n=7 in each group). Group I mice only received subcutaneously 100 µl/day phosphate-buffered saline (PBS), whereas group II, III and IV mice were subcutaneously administrated 100 µg/day bleomycin (1 mg bleomycin dissolved in 1ml PBS). In addition to bleomycin, group III and IV mice were received intraperitoneally 50 µg and 250 µg rituximab respectively on the first and fourteenth days.Animals were sacrificed, at the end of fourth week, and blood and tissue samples were then obtained for further analysis. TGF-ß1 serum levels, dermal thicknesses, the numbers of inflammatory cells on the dermal layer and ?-smooth muscle actin-positive (?-SMA+) cells were determined.Bleomycin administrations increased dermal thicknesses, the numbers of inflammatory cells on the dermal layer and activity of myofibroblastic cells. When rituximab is administrated together with bleomycin, skin fibrosis, infiltration of inflammatory cells and activity of myofibroblastic cells were not observed.In conclucion, anti-fibrotic effect of rituximab on bleomycin-induced experimental scleroderma model may suggest that B cells have a role on the pathegenesis of scleroderma.Key Words: Scleroderma, Bleomycin, Rituximab