308-LB: A Short Period of Exposure to Air Pollution (PM2.5) Is Sufficient to Induce Dysbiosis, Hyperphagia, and Fat Mass Gain

Fine particulate matter (PM 2.5 ) is the most harmful component of air pollution and is associated with an increased risk of cardiometabolic diseases, such as T2DM. The small diameter of PM 2.5 allows it to be inhaled and subsequently invades tissues through the airways. Intake of PM 2.5 is also possible even if this is not the primary route of entry of PM 2.5 into the body. However, it is still unclear whether ingestion and inhalation of PM 2.5 in a short time would be sufficient to alter the gut microbiota and energy metabolism. Thus, we aimed to investigate whether 1 day or 5 days of exposure to PM 2.5 would be enough to alter energy metabolism and the composition of gut microbiota at the phylum level. Male C57BL/6J mice on a chow diet were exposed to PM 2.5 in a fixed dose (600 μg/m3/day) or filtered air (FA) for 1 day or 5 days using the Harvard Ambient Fine Particle Concentrator. The 1-day exposure to PM 2.5 did not change body weight, food intake or energy expenditure, but altered the composition of the gut microbiota compared to the FA group. In the gut, there was a reduction of Bacteroidetes and Verrucomicrobia and an increase of Tenericutes. After 5 days of exposure to PM 2.5 , there was an increase in food intake, fat mass. In the gut, there was an increase in Firmicutes and in the ratio of Firmicutes/Bacteroidetes after 5 days of exposure to PM 2.5 compared to the FA group. Thus, after a short period of exposure to air pollution, there was a significant change in the gut microbiota, beginning with the reduction of the Bacteroidetes and Verrucomicrobia phyla and the increase of the phylum Tenericutes with 1 day of exposure. This result occurred without altering the energy balance. A robust dysbiosis installation happened after 5 days of exposure to PM 2.5 , Firmicutes/Bacteroidetes ratio was elevated and associated with fat mass gain, and hyperphagia. Disclosure O.P. Zordao: None. A. Santos: None. C.M. Campolim: None. R. Ataide Lima: None. C.K. Ferreira: None. M. Saad: None. P. Saldiva: None. M. Veras: None. P.O. Prada: None. Funding Sao Paulo Research Foundation (2017/18498-62017/19703-22017/11518-1)