Abstract
Emerging evidence has highlighted the connection between exposure to air pollution and the increased risk of obesity, metabolic syndrome, and comorbidities. Given the recent interest in studying the effects of ultrafine particle (UFP) on the health of obese individuals, this study examined the effects of gastrointestinal UFP exposure on gut microbial composition and metabolic function using an in vivo murine model of obesity in both sexes. UFPs generated from light-duty diesel engine combustion of petrodiesel (B0) and a petrodiesel/biodiesel fuel blend (80:20 v/v, B20) were administered orally. Multi-omics approaches, including liquid chromatography–mass spectrometry (LC–MS) based targeted metabolomics and 16S rRNA gene sequence analysis, semi-quantitatively compared the effects of 10-day UFP exposures on obese C57B6 mouse gut microbial population, changes in diversity and community function compared to a phosphate buffer solution (PBS) control group. Our results show that sex-specific differences in the gut microbial population in response to UFP exposure can be observed, as UFPs appear to have a differential impact on several bacterial families in males and females. Meanwhile, the alteration of seventy-five metabolites from the gut microbial metabolome varied significantly (ANOVA p < 0.05) across the PBS control, B0, and B20 groups. Multivariate analyses revealed that the fuel-type specific disruption to the microbial metabolome was observed in both sexes, with stronger disruptive effects found in females in comparison to male obese mice. Metabolic signatures of bacterial cellular oxidative stress, such as the decreased concentration of nucleotides and lipids and increased concentrations of carbohydrate, energy, and vitamin metabolites were detected. Furthermore, blood metabolites from the obese mice were differentially affected by the fuel types used to generate the UFPs (B0 vs. B20).
Highlights
Emerging evidence has highlighted the connection between exposure to air pollution and the increased risk of obesity, metabolic syndrome, and comorbidities
A close examination of the Principal coordinate analyses (PCoA) plot from Fig. 1A indicated that oral administration of the different types of ultrafine particle (UFP) to female obese mice was associated with differences in the gut microbial population compared to the phosphate buffer solution (PBS) control group
Three of these families, including Coriobacteriaceae, Bacteroidaceae, and Peptostreptococcace, were found significantly changed in female obese groups treated B20 UFP compared to the PBS control group (Table S4b), while Coriobacteriaceae and Peptostreptococcace showed an increase in the B20 treatment and Bacteroidaceae abundance decreased in the B20 treatment
Summary
Emerging evidence has highlighted the connection between exposure to air pollution and the increased risk of obesity, metabolic syndrome, and comorbidities. Given the recent interest in studying the effects of ultrafine particle (UFP) on the health of obese individuals, this study examined the effects of gastrointestinal UFP exposure on gut microbial composition and metabolic function using an in vivo murine model of obesity in both sexes. Exposure to elevated concentrations of ambient particulate matter with an aerodynamic diameter less than 10 μm and 2.5 μm (PM10 and PM2.5) is associated with increased pulmonary and cardiovascular diseases[7,8], Scientific Reports | (2021) 11:6906. Since 2007, significant technological improvements in engine and pollution control designs for diesel engines, including the use of “cleaner” fuels, have lowered regulated exhaust emissions (i.e., PM, NOx, and CO), but the unregulated UFPs are still produced and pose an important human health r isk[13,14,15]. Other investigators have reported reduced ROS production and DNA damage for biodiesel compared to petrodiesel[13]
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