In Crohn's disease, immune damage to the gut wall is both induced and modified by the gut microflora, challenging researchers to solve the maze of interactions exploitable for therapeutic benefit. Whether these microbial 'guests' are worsening or helping in this scenario is still open to debate. In 'Bench to Bedside', Warren Strober highlights mice studies showing that certain microbes in the gut have a protective role promoting a shift towards an increased regulatory response that protects from recurrence of the disease. In 'Bedside to Bench', Thomas MacDonald examines how human studies using strategies to block soluble proinflammatory cytokines—despite solid supporting data from animal models—have shown disappointing results compared with therapies that neutralize soluble cytokines but also deplete proinflammatory cells, calling into question whether targeting a single soluble cytokine will ever be useful to treat people with Crohn's disease.
