Immunomodulation of inflammatory conditions utilizing Follistatin-like Protein-1 and agents that bind thereto

Follistatin-like protein (FSTL-1) is a secreted glycoprotein of unknown function, first isolated from mouse osteoblastic cells as a transforming growth factor-β1-inducible gene. The inventors have discovered that FSTL-1 is a proinflammatory mediator. As such, the invention provides for composition and methods of using agents that bind to FSTL-1 to modulate various types of inflammation (e.g., autoimmune diseases). Inhibitors and antagonists of FSTL-1, particularly antibodies or antibody fragments, may be used to treat conditions related to inflammation, such as arthritis. In addition, the inventors have discovered that FSTL-1 has a role in the Th17 pathway. Accordingly, the invention provides for compositions and methods of using agents which bind to FSTL-1 to modulate the generation of Th17 cells. Such agents are useful for delaying development of and treating diseases associated with undesired production of Th17 cells, such as autoimmune diseases. Furthermore, since FSTL-1 is a proinflammatory mediator with a role in cancer, the invention provides for compositions and methods of using a pharmaceutical composition of FSTL-1 to delay development of or treat cancer.