Leukocyte mitochondrial DNA copy number and built environment in Mexican Americans: a cross-sectional study

Abstract

Mitochondrial DNA (mtDNA) copy number in leukocytes has been regarded as a biomarker for various environmental exposures and chronic diseases. Our previous study showed that certain demographic factors (e.g. age, gender, BMI, etc.) significantly affect levels of leukocyte mtDNA copy number in Mexican Americans. However, the effect of the built environment on leukocyte mtDNA copy number has not been studied previously. In this cross-sectional study, we examined the association between multiple components of the built environment with leukocyte mtDNA copy number among 5,502 Mexican American adults enrolled in Mano-A-Mano, the Mexican American Cohort Study (MACS). Based on the median levels of mtDNA copy number, the study population was stratified into low mtDNA copy number group (< median) and high mtDNA copy number group (≥ median). Among all built environment exposure variables, household density and road/intersection ratio were found to be statistically significant between groups with low and high mtDNA copy number (P < 0.001 and 0.002, respectively). In the multivariate logistic regression analysis, individuals living in areas with elevated levels of household density had 1.24-fold increased odds of having high levels of mtDNA copy number [Odds ratio (OR) = 1.24, 95% confidence interval (CIs) 1.08, 1.36]. Similarly, those living in areas with elevated levels of road/intersection ratio had 1.12-fold increased odds of having high levels of mtDNA copy number (OR = 1.12, 95% CI 1.01, 1.27). In further analysis, when both variables were analyzed together in a multivariate logistic regression model, the significant associations remained. In summary, our results suggest that selected built environment variables (e.g. population density and road/intersection ratio) may influence levels of mtDNA copy number in leukocytes in Mexican Americans.

Land use mix and leukocyte telomere length in Mexican Americans

“…Mexican Americans living in areas with a high density of roads had higher body mass index (BMI) than their counterparts 11 . We also observed that selected built environment factors (e.g., population density and road/intersection ratio) affect leukocyte mitochondrial DNA copy number levels, a biomarker linking environmental exposures and chronic diseases 12 .…”

“…The data on built environment factors are presented in our previous publication 11 , 12 . In brief, to represent essential areas of the built environment, we assessed physical activity environment, land use variety, and food environment., Five exposure variables [population density (people per km 2 ), household density (households per km 2 ), road density (number of road links per km 2 ), and intersections density (number of road intersections per km 2 )] within a half-mile radius surrounding each participant's residence were included in the physical activity environment.…”

Reduced leukocyte mitochondrial copy number in metabolic syndrome and metabolically healthy obesity

“…This investigation centered only on mtDNA CN and did not focus on additional elements that could impact on mitochondrial bioenergetics and disease, such as mtDNA haplotypes and sequence variation ( 84 , 85 ). The environmental and lifestyle determinants of mtDNA CN are poorly understood, with several factors being implicated ( 70 ). Importantly, statins have pleiotropic immunomodulatory effects and can negatively affect mitochondrial function and mtDNA CN ( 86 ).…”

Mitochondrial health quality control: measurements and interpretation in the framework of predictive, preventive, and personalized medicine

“…Several studies described the alterations only in mtDNA copy number in health and disease [ 64 – 69 ]; however, mtDNA alone is not enough indicative for the mitochondrial health evaluation. It is important to consider additional parameters such as mitochondrial enzymatic activities or modulations in bioenergetic pathways.…”