Exposure to concentrated ambient PM (CAPM) induces intestinal disturbance via inflammation and alternation of gut microbiome.

Air pollution causes a great disease burden worldwide. Recent evidences suggested that PM contributes to intestinal disease. The objective of present study was to investigate the influence of ambient PM on intestinal tissue and microbiome via whole-body inhalation exposure. The results showed that high levels and prolonged periods exposure to concentrated ambient PM (CAPM) could destroy the mucous layer of the colon, and significantly alter the mRNA expression of tight junction (Occludin and ZO-1) and inflammation-related (IL-6, IL-10 and IL-1β) genes in the colon, comparing with exposure to the filtered air (FA). The composition of intestinal microbiome at the phylum and genus levels also varied along with the exposure time and PM levels. At the phylum level, Bacteroidetes was greatly decreased, while Proteobacteria was increased after exposure to CAPM, comparing with exposure to FA. At the genus level, Clostridium XlVa, Akkermansia and Acetatifactor, were significantly elevated exposure to CAPM, comparing with exposure to FA. Our results also indicated that high levels and prolonged periods exposure to CAPM altered metabolic functional pathways. The correlation analysis showed that the intestinal inflammation was related to the alteration of gut microbiome induced by CAPM exposure, which may be a potential mechanism that elucidates PM-induced intestinal diseases. These results extend our knowledge on the toxicology and health effects of ambient PM.