Acute gastrointestinal graft-versus-host disease (GI GVHD) is a complication after hematopoietic stem cell transplant with high morbidity and mortality. In particular, steroid-refractory GI GVHD can be difficult to treat. Recent investigations have revealed that patients after transplant can experience intestinal dysbiosis contributing to the progression of GVHD. Modulation of the gut microbiome through dietary intake could potentially improve the intestinal dysbiosis in GI GVHD. In this case series, we present 3 patients where dietary therapy was used in conjunction with immunosuppression to achieve clinical remission of GI GVHD.

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract caused by a dysregulated immune response to the fecal microbiota. Very early-onset inflammatory bowel disease (VEO-IBD) refers to a subgroup of pediatric patients with IBD diagnosed before 6 years of age. This subgroup is often characterized by increased severity, aggressive progression, strong family history of IBD, and often poor response to conventional treatments. Nutritional therapies have been utilized to treat IBD, but their role in VEO-IBD is unclear. Disease behavior in VEO-IBD is often different from disease in adolescents and adults, as it is often restricted to the colon and refractory to standard medical therapies. Up to 25% of VEO-IBD patients have an identified underlying immunodeficiency, which may impact response to therapy. While specific mutations in interleukin 10 (IL-10), the IL-10 receptor (IL-10R), and mutations in NCF2, XIAP, LRBA, and TTC7 have been identified in VEO-IBD, polymorphisms in these genes are also associated with increased risk of developing IBD in adolescence or adulthood. We describe two cases in which infants presenting with VEO-IBD achieved clinical remission using exclusive enteral nutrition, a formula-based diet which has been shown to induce remission in older children with active Crohn\'s disease.