Integrin alpha-9 (ITGA9) is a subunit of the α9β1 integrin heterodimer, a cell surface receptor involved in mediating cell-cell and cell-extracellular matrix interactions. Unlike many integrins, α9β1 binds ligands such as vascular cell adhesion molecule-1 (VCAM-1), tenascin-C, and osteopontin, playing critical roles in immune regulation, angiogenesis, and tissue repair. It is highly expressed in immune cells (e.g., neutrophils, lymphocytes), endothelial cells, and certain epithelial cells, and is implicated in inflammatory responses, lymphatic development, and cancer progression.
ITGA9 antibodies are research tools or therapeutic candidates designed to target this subunit. In research, they help study α9β1's functional roles—for example, in leukocyte trafficking during inflammation or tumor cell metastasis. Therapeutically, blocking ITGA9 may inhibit pathological processes: preclinical studies suggest anti-ITGA9 antibodies could suppress cancer invasion (e.g., melanoma, lung cancer) by disrupting cell adhesion and signaling. They also show potential in treating fibrotic diseases (e.g., pulmonary fibrosis) or autoimmune disorders (e.g., rheumatoid arthritis) by modulating immune cell infiltration. Challenges include optimizing specificity to avoid off-target effects and understanding context-dependent roles, as ITGA9 has dual functions in both promoting and suppressing disease depending on the microenvironment. Current efforts focus on antibody engineering and validating clinical relevance across disease models.