While there are conflicting data as to whether claudin-2 is induced or repressed in response to undernutrition,41–43 convincing evidence supports induced expression.41,42 Further, induced claudin-2 is associated with many enteropathies that resemble malnutrition histologically, including Crohn’s disease, ulcerative colitis, HIV enteropathy, celiac disease, and enteric infections, all of which present clinically with diarrhea.40,43,77 Regarding barrier function, IAP and IL-8 secretion were examined. This evidence concerns the gene CLDN2 and celiac disease.