Translocation of black carbon particles to human intestinal tissue

Abstract

Background Evidence is accumulating that elevated levels of particulate air pollution, including black carbon, have been linked to gastrointestinal disorders and a lower intestinal bacterial richness and diversity. One of the hypothesized underlying mechanisms is the absorption of air pollution-related particles from the gastrointestinal tract. Methods We visualized and quantified black carbon particles via white light generation under femtosecond-pulsed laser illumination in ileum and colon biopsies of five human patients. The biodistribution was assessed in three different layers ( i.e., mucosa, submucosa, and muscularis propria). Findings Black carbon particles could be identified in all three tissue layers of the ileum and colon biopsies of five participants (two men and three women; mean +/- standard deviation age, 76.40 +/- 7.37 years), and their carbonaceous nature was confirmed via emission fingerprinting. The median (+/- SD) black carbon load was borderline statistically significantly higher in the ileum compared to the colon (1.21 x 10(5) +/- 1.68 x 10(4) particles/mm(3) versus 9.34 x 10(4) +/- 1.33 x 10(4) particles/mm(3); p = 0.07) and was driven by a difference in black carbon load in the submucosa layer (p = 0.01). Regarding the three tissue layers, loads were higher in the submucosa, compared with the mucosa (ileum: +76%, p < 0.0001; colon: +70%, p = 0.0001) and muscularis propria (ileum: +88%, p < 0.0001; colon: +88%, p < 0.0001). In ileum, loads were borderline higher in the mucosa versus muscularis propria (p = 0.09). Interpretation This explorative study provides real-life evidence that black carbon particles can reach the intestinal tissue and accumulate in different intestinal tissue layers. These findings support further research into how particulate air pollution directly affects gastrointestinal health. Funding Thessa Van Pee holds a doctoral fellowship from the Research Foundation Flanders (FWO), grant number: 11C7421N. Tim Nawrot is a Methusalem grant holder. Copyright (c) 2024 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).