How does vedolizumab work in the body?
Vedolizumab is a monoclonal antibody that targets the gut-specific immune trafficking pathway. It binds to the integrin α4β7 on immune cells and blocks its interaction with MAdCAM-1 (mucosal addressin cell adhesion molecule-1) on gut blood vessels. This prevents the targeted movement of those lymphocytes into intestinal tissue, which reduces intestinal inflammation.
Why does blocking α4β7/ MAdCAM-1 matter for inflammatory bowel disease?
In inflammatory bowel disease, immune cells use adhesion signals to enter the gut lining. By blocking α4β7’s “homing” signal to the gut (via MAdCAM-1), vedolizumab reduces accumulation of inflammatory T cells in the gastrointestinal tract, helping lower inflammation in diseases such as ulcerative colitis and Crohn’s disease.
What is the difference between vedolizumab’s gut-selective action and natalizumab?
Both drugs are antibody therapies that interfere with leukocyte trafficking, but they target different integrins. Vedolizumab is gut-selective because it blocks α4β7 binding to MAdCAM-1, a gut-associated adhesion pathway. This contrasts with natalizumab, which blocks a broader integrin interaction linked to trafficking into the central nervous system as well, leading to different risk considerations.
What does this mean for onset and effects?
Because vedolizumab works by changing where inflammatory immune cells can go (rather than directly suppressing every immune pathway), clinical improvement develops as inflammatory cell trafficking is reduced over time, rather than through an immediate anti-inflammatory effect.