Review article: helminths as therapeutic agents for inflammatory bowel disease

Over the last decade major advances have been made in our understanding of the mechanisms and mediators of inflammation that hold the promise of the development of new therapies for inflammatory disease. While much is to be gleaned from the application of new technologies, assessment of the age-old host-parasite relationship may also provide insights on how to counter pathological inflammatory events. In the case of inflammatory bowel disease [particularly Crohn's disease, which is associated with T helper 1 (Th1) events] it is proposed that infection with parasitic helminths would be beneficial: the paradigm being that of immune deviation, where Th2 cytokines mobilized in response to the helminth will prevent or antagonize the disease-promoting Th1 events in the gut. The situation is unlikely to be this simple. Here we review and critique the data in support of helminth therapy for inflammatory bowel disease, drawing attention to the gaps in knowledge and presenting a view on how the field may be advanced. While the concept of helminth therapy may be superficially unappealing, this review may convince the reader of the value of more extensive analyses of the impact of helminth infection on enteric inflammation.