Targeting Leukocyte Trafficking in Inflammatory Bowel Disease

In the last two decades, understanding of inflammatory bowel disease (IBD) immunopathogenesis has expanded considerably. Histopathological examination of the intestinal mucosa in IBD demonstrates the presence of a chronic inflammatory cell infiltrate. Research has focused on identifying mechanisms of immune cell trafficking to the gastrointestinal tract that may represent effective gut-selective targets for IBD therapy whilst avoiding systemic immunosuppression that may be associated with off-target adverse effects such as infection and malignancy. Integrins are cell surface receptors that can bind to cellular adhesion molecules to mediate both leukocyte homing and retention. In 2014, Vedolizumab (Entyvio®) was the first anti-integrin (anti-α4ß7 monoclonal antibody) treatment to be approved for use in IBD. Several other anti-integrin therapies are currently in advanced stages of development, including novel orally administered small-molecule drugs. Drugs targeting alternative trafficking mechanisms such as mucosal addressin cellular adhesion molecule-1 and sphingosine-1-phosphate receptors are also being evaluated. Here, we summarise key established and emerging therapies targeting leukocyte trafficking that may play an important role in realising the goal of stratified precision medicine in IBD care.