Fig. 1: Titanium dioxide in human intestinal tissues.
From: Immunocompetent cell targeting by food-additive titanium dioxide
a Tilescanned image acquired by confocal reflectance microscopy. Reflectant foci were detected along the follicle base consistent with previously-reported mineral particle-containing pigment cells. Of note, similar reflectant foci were also present apically in the immuno-active, subepithelial dome tissue-region, and away from the patch in the (c) lamina propria of the regular villous mucosa (VM). Translucent red circle-markers are placed on the reflectant foci to aid visualisation. b, d, e, Correlative SEM/EDX analyses performed on the same tissue section shown in (a/c). The pigment cell region is shown in (b) where X-ray signal for both Al (attributable to aluminosilicates) and Ti (attributable to titanium dioxide) was found. EDX analyses in the (d) villous mucosa and (e) subepithelial dome regions showed reflectant foci were attributable to Ti. b, d, e In all instances the elemental data for Ti were a near-exact match for the reflectant foci, whereas (b) areas with Al signal alone did not reflect. The image-data presented in (a–e) are representative of independent repeats in n = 2 samples. f Reflectance microscopical analyses of nine, randomly-drawn human samples (six frozen, three formalin-fixed paraffin embedded (FFPE)) showed reflectant foci consistent with TiO2 in the subepithelial dome of every sample. Scale bars: (a) = 50 μm; (b, d, e) = 10 μm; (c, f) = 50 μm with 10 μm insets.
