Rheumatoid arthritis (RA) is characterized by exuberant angiogenesis and leukocyte infiltration in the synovial tissue (ST). We have shown that the soluble adhesion molecule E-selectin (sE-selectin) induces angiogenesis in RA (see Koch et. al, Nature 376:517). The mechanism by which this molecule mediates angiogenesis is by binding sialyl Lewisx on endothelial cells (ECs). It is likely that cytokines present in the inflammatory milieu upregulate the production of cell surface adhesion molecules. These molecules are then shed and induce other endothelial cells to begin the angiogenic process. We have developed a novel monoclonal antibody (mAb) 4A11 by immunizing mice with cells from inflamed human ST lining joints. This mAb detects an antigen expressed on ECs in synovium, skin, thymus, and lymphoid organs. Moreover, this antigen is inducible and upregulated in human RA ST. MAb 4A11 detects the glycoconjugates H-5-2 (abbreviated H) and Lewisy-6 (Ley), collectively termed Ley/H. Additionally, Ley is structurally very similar to Lex, whose sialylated form is the EC ligand for the angiogenic mediator sE- selectin. We have found that these glycoconjugates, or easily obtainable glucose analogs of these glycoconjugates, termed H-2g and Leyg, respectively, are angiogenic in vivo, mediate monocyte recruitment and leukocyte-EC adhesion, as well as induce RA ST fibroblast production of matrix metalloproteinase-2. Synthesis of Ley and H are controlled by fucosyl transferases (termed futs). Our preliminary data suggests that fut1 deficient mice are also deficient in development of both angiogenesis and arthritis.
The aim of the proposed studies is to examine the role of futs in inflammation and angiogenesis. We will determine: I) if fut1 gene deficient mouse microvascular ECs display alterations in leukocyte adhesion and angiogenesis in vitro; II) fut1 gene deficient mice display defective leukocyte recruitment in vivo; III) mice display defective angiogenesis in vivo; and if IV) fut1 gene deficient mice are resistant to arthritis development in vivo. The proposed studies are very relevant to the VA mission, as arthritidies, such as RA, are very common conditions affecting a large proportion of the population each year. Our results would additionally have potential therapeutic benefits to conditions characterized by leukocyte recruitment and angiogenesis, such as wound repair and solid tumor growth. Ever rising numbers of veterans each year are afflicted by malignancies and our results may eventually benefit these veterans too. Thus, the proposed studies should initially shed light on futs as likely novel targets in RA therapy. Examining fut1 deficient mice, in which synthesis of Ley/H is impaired, provides a rare opportunity to establish a role for fucosylation in inflammation, arthritis and angiogenesis. These studies should form the basis for us to investigate the role of futs in human RA in the future as well as potentially open up an entirely new family of targets for the treatment of RA.
PROJECT NARRATIVE Rheumatoid arthritis (RA) is an autoimmune disease affecting 1% of the population. Inflammation, cell recruitment, and angiogenesis are all vital components of the pathogenesis of RA. We have found that enzymes termed fucosyl transferases are important to these processes in inflammatory arthritis. As Veteran's suffer from a number of disorders in which angiogenesis is important, such as wound repair and tumor growth, these studies may have broad applicability to developing therapies for angiogenesis dependent diseases. Additionally, initially, studies such as these may open up a new family of targets in RA therapy.