PM2.5 and Serum Metabolome and Insulin Resistance, Potential Mediation by the Gut Microbiome: A Population-Based Panel Study of Older Adults in China

Abstract

Background: Insulin resistance (IR) affects the development of type 2 diabetes mellitus (T2DM), which is also influenced by accumulated fine particle air pollution [particulate matter (PM) with aerodynamic diameter of ( )] exposure. Previous experimental and epidemiological studies have proposed several potential mechanisms by which contributes to IR/T2DM, including inflammation imbalance, oxidative stress, and endothelial dysfunction. Recent evidence suggests that the imbalance of the gut microbiota affects the metabolic process and may precede IR. However, the underlying mechanisms of , gut microbiota, and metabolic diseases are unclear. Objectives: We investigated the associations between personal exposure to and fasting blood glucose and insulin levels, the IR index, and other related biomarkers. We also explored the potential underlying mechanisms (systemic inflammation and sphingolipid metabolism) between and insulin resistance and the mediating effects between and sphingolipid metabolism. Methods: We recruited 76 healthy seniors to participate in a repeated-measures panel study and conducted clinical examinations every month from September 2018 to January 2019. Linear mixed-effects (LME) models were used to analyze the associations between and health data (e.g., functional factors, the IR index, inflammation and other IR-related biomarkers, metabolites, and gut microbiota). We also performed mediation analyses to evaluate the effects of mediators (gut microbiota) on the associations between exposures ( ) and featured metabolism outcomes. Results: Our prospective panel study illustrated that exposure to was associated with an increased risk of higher IR index and functional biomarkers, and our study provided mechanistic evidence suggesting that exposure may contribute to systemic inflammation and altered sphingolipid metabolism. Discussion: Our findings demonstrated that was associated with the genera of the gut microbiota, which partially mediated the association between and sphingolipid metabolism. These findings may extend our current understanding of the pathways of and IR. https://doi.org/10.1289/EHP9688

Impact of Air Pollution on the Composition and Diversity of Human Gut Microbiota in General and Vulnerable Populations: A Systematic Review

“…Finally, 12 articles were considered eligible to be included in the systematic review, but 2 articles were excluded for missing data. A total of 10 articles were used for the data extraction [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ]. The PRISMA flow diagram in Figure 1 illustrates the search results.…”

“…The included studies (nine cross-sectional and one cohort study) were published from 2018 to 2022 [ 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ] ( Table 2 ). Among the ten studies, two of them were conducted in America [ 39 , 45 ], seven in China [ 36 , 37 , 38 , 40 , 41 , 42 , 43 ], and one in Europe (Finland) [ 44 ], and the sample size was very variable, ranging from 21 to 6627 subjects.…”

“…Regarding exposure time, short-term exposure (from 2 to 5 days) to air pollutants was considered in four studies [ 37 , 41 , 42 ], whereas long-term exposure (28 days to 2 years) was investigated in six studies [ 36 , 38 , 39 , 40 , 44 , 45 ]. Moreover, the methods of exposure assessments varied among studies: daily air quality index scores assigned using the monitoring data of China National Environmental Monitoring Centre [ 38 ], levels of urbanization [ 40 ], ambient monitoring station [ 41 ], real-time personal exposure [ 37 , 42 ], passive sampling devices [ 44 ], and other various modelled estimates ( n = 3) [ 36 , 43 , 45 ] were used ( Table 1 ).…”

Long-Term Exposure to Fine Particulate Matter and the Risk of Chronic Liver Diseases: A Meta-Analysis of Observational Studies

“…Gut microbiota dysbiosis and insulin resistance might be one of possible mechanisms. Both in vivo and prospective studies have indicated that chronic exposure to PM2.5 caused dysbiosis of the gut microbiota and may subsequently contribute to the development of abnormal glucose metabolism and insulin resistance [ 55 , 56 , 57 , 58 ]. Previous studies presented that gut microbiota affected bioprocessing of bile acids and production of pro-inflammatory intermediate metabolites resulting in hepatic disorders [ 59 , 60 ].…”

Breast microbiome associations with breast tumor characteristics and neoadjuvant chemotherapy: A case-control study

“…The activation of lipid and fatty acid pathways is most likely to be used as sources of energy that promotes BC cell growth in addition to pathogenesis. The previous investigation on PM 2.5 and metabolism revealed that the impact of PM 2.5 on the genera of the gut microbiota could partially mediate the relationship between PM 2.5 and sphingolipid metabolism ( 48 ). In addition, the gut microbiota can affect host health by plasma metabolites ( 49 ).…”