Integrin subunit alpha 4 (ITGA4) (ITGA4)

The target "Immune cell trafficking to CNS" refers to a biological process rather than a single molecular entity; however, it is most specifically modulated by targeting Integrin subunit alpha 4 (ITGA4), also known as CD49d. ITGA4 is a critical transmembrane receptor that mediates the adhesion and migration of leukocytes across the vascular endothelium (UniProt: P13612). It forms heterodimers with either the beta-1 subunit to create Very Late Antigen-4 (VLA-4) or the beta-7 subunit to create alpha-4-beta-7 integrin. In the context of the central nervous system (CNS), VLA-4 interacts with Vascular Cell Adhesion Molecule-1 (VCAM-1) on the blood-brain barrier, facilitating the entry of inflammatory cells into the brain and spinal cord (PubMed: 15548778). This process of immune cell trafficking is a central driver of neuroinflammatory diseases like Multiple Sclerosis (MS). Therapeutic agents such as Natalizumab target the alpha-4 subunit to block this trafficking, significantly reducing clinical relapses and MRI activity in MS patients (PubMed: 16510744). However, the resulting reduction in CNS immune surveillance poses a significant safety risk, most notably the development of Progressive Multifocal Leukoencephalopathy (PML) due to JC virus reactivation (FDA: Tysabri Label).

Other names

CD49dVLA-4 subunit alphaIntegrin alpha-4Antigen CD49DIntegrin subunit alpha 4

Drugs targeting this pathway, such as Natalizumab, function as monoclonal antibodies that bind to the alpha-4 subunit of integrin heterodimers (VLA-4 and alpha-4-beta-7). This binding prevents the interaction between these integrins on the surface of leukocytes and their ligands, such as Vascular Cell Adhesion Molecule-1 (VCAM-1) on the vascular endothelium. By blocking this adhesion step, the drugs inhibit the transmigration of immune cells across the blood-brain barrier, thereby preventing neuroinflammation (PubMed: 15548778, 16510744).