zymosan-induced arthritis

There is evidence that complement components induce cell migration in mesenchymal stem cells and regulate cytokine production in osteoblastic cells thus playing a regulatory role in normal bone formation. The aim of the present study was to investigate the involvement of complement system in the differentiation of bone marrow cells in complement-depleted model of rheumatoid arthritis (RA). Arthritis was induced by intraarticular injection of zymosan in cobra venom factor (CVF)-treated mice depleted of functional complement. The expression of different markers by bone marrow [1], on fibroblasts (CD29), mesenchymal cells (CD105), dendritic cells (CD14, CD86), osteoclasts (CD265), cells expressing Dectin1 (CD369) and megakaryocytes (CD62P) was determined by flowcytometry. The lack of functional complement activity at the point of arthritis initiation (day 3) lead to an increase of fibroblast and megakaryocyte populations, to a decrease of mature and dectin1 positive populations, while the number of mesenchymal cells was not changed, all compared to arthritic mice. Immunohistochemical staining showed that low complement activity diminished arthritis-induced generation of megakaryocytes and platelets in BM. Chronic inflammation during erosive conditions such as rheumatoid arthritis, leads to dysregulated differentiation and prolifеration of bone cells, inflammation of synovial membrane and bone marrow, and degradation of cartilage and bone. Present results point that the lack of functional complement changed the ratio between different cell populations that can be used for determining the development and stage of rheumatoid arthritis and can help finding of new therapeutic approaches.