Alteration of fecal tryptophan metabolism correlates with shifted microbiota and may be involved in pathogenesis of colorectal cancer

Figure 2 Immunohistochemical staining for Zonula occludens-1 and its correlation with fecal indoles/tryptophan ratio (× 200 magnification). Immunoreactivity of Zonula occludens-1 (ZO-1) tended to be decreased in colorectal adenoma (B) and colorectal cancer (C) compared to controls (A) as shown in the figure (scale bar = 100 μm); D: There was a positive correlation between fecal indoles/tryptophan ratio and ZO-1 protein in all subjects (P = 0.045). MOD: Mean optical density; Trp: Tryptophan; ZO-1: Zonula occludens-1.