Extracellular flux analyses reveal differences in mitochondrial PBMC metabolism between high-fit and low-fit females

Abstract

Analyzing metabolism of peripheral blood mononuclear cells (PBMCs) can possibly serve as a cellular metabolic read-out for lifestyle factors and lifestyle interventions. However, the impact of PBMC composition on PBMC metabolism is not yet clear, neither is the differential impact of a longer-term lifestyle factor versus a short-term lifestyle intervention. We investigated the effect of aerobic fitness level and a recent exercise bout on PBMC metabolism in females. PBMCs from 31 young female adults divided into a high-fit (V̇O2peak ≥ 47 mL/kg/min, N = 15) and low-fit (V̇O2peak ≤ 37 mL/kg/min, N = 16) group were isolated at baseline and overnight after a single bout of exercise (60 minutes, 70% V̇O2peak). Oxygen consumption rate (OCR) and glycolytic rate (GR) were measured using extracellular flux (XF) assays and PBMC subsets were characterized using fluorescence-activated cell sorting (FACS). Basal OCR, FCCP-induced OCR, spare respiratory capacity, ATP-linked OCR, and proton leak were significantly higher in high-fit compared to low-fit females (all P < 0.01), while no significant differences in glycolytic rate (GR) were found (all P > 0.05). A recent exercise bout did not significantly affect GR or OCR parameters (all P > 0.05). The overall PBMC composition was similar between high-fit and low-fit females. Mitochondrial PBMC function was significantly higher in PBMCs from high-fit compared to low-fit females, which was unrelated to PBMC composition and not impacted by a recent bout of exercise. Our study reveals a link between PBMC metabolism and levels of aerobic fitness, increasing the relevance of PBMC metabolism as a marker to study the impact of lifestyle factors on human health.

Single and Joined Behaviour of Circulating Biomarkers and Metabolic Parameters in High-Fit and Low-Fit Healthy Females

“…All 102 biomarkers were analysed in samples from a well-characterised study [ 21 , 22 , 23 ] of healthy females. This study population represents high-fit (V̇O 2 peak ≥ 47 mL/kg/min, N = 15) and low-fit (V̇O 2 peak ≤ 37 mL/kg/min, N = 15) females ( Table 1 ), which was supported by a significantly higher skeletal muscle mitochondrial capacity for ATP generation [ 21 ] and a better mitochondrial function, including higher basal and uncoupled oxygen consumption rate, in peripheral blood mononuclear cells (PBMCs) [ 22 ] in the high-fit compared to the low-fit females.…”

“…The original objectives of the study were to investigate whether differences exist in vitamin B2 status, in muscle mitochondrial capacity, and in circulating cellular and molecular parameters between high aerobically fit (high-fit) and low aerobically fit (low-fit) females with a validated difference in V̇O 2 peak, and after a recent bout of exercise. Previously, we found a significant difference in skeletal muscle mitochondrial oxygen consumption rate [ 21 ] and mitochondrial function in white blood cells [ 22 ] between the high-fit and low-fit females in our healthy study population. Circulating biomarker and metabolic parameter analysis in this study will now show whether single biomarkers, functional biomarkers, metabolic parameter categories, total biomarkers, and metabolic parameter profiles differ between high-fit and low-fit females, i.e., whether the biomarkers and metabolic parameter, including those that discriminate between health and disease, already differ in healthy individuals with potentially a different long term disease risk, in the basal state and after a recent bout of exercise.…”

“…Given that the levels of the analysed biomarkers and metabolic parameters were similar among the healthy females in our study, and multiple of these biomarkers and metabolic parameters showed dysregulation during disease, our findings imply that this biomarker and metabolic parameters set could be used to monitor progress from a healthy to an unhealthier state and may be used in health improvement interventions. Previously, we reported that maximal and basal respiration of the peripheral blood mononuclear cell (PBMC) fraction was different between the high-fit and low-fit individuals that were studied here, but there was no additional effect of exercise [ 22 ]. This suggests that PBMC oxidative metabolism may be a more sensitive fitness biomarker and metabolic parameter than the circulating metabolites studied here.…”

“…One limitation of our study is the relatively small sample size with mixed Caucasian and non-Caucasian healthy females. Nevertheless, it allowed us to identify PBMC mitochondrial oxygen consumption rate as a biomarker and metabolic parameter for differences in fitness in healthy females [ 22 ], while here we established the sensitivity of circulating biomarkers and metabolic parameters to a recent bout of exercise. Another limitation of our study is that we could not determine the contribution of intraindividual variation, i.e., the day-to-day variation within an individual, as we sampled only twice in a relatively short time span.…”

Whole‐Genome Transcriptomics of PBMC to Identify Biomarkers of Early Metabolic Risk in Apparently Healthy People with Overweight‐Obesity and in Normal‐Weight Subjects

“…Particularly, the interest in the fraction of peripheral blood mononuclear cells (PBMC) as a biological material for searching for biomarkers related to different diseases, e.g., obesity has grown in the last years. [16][17][18][19] Apart from their role in immunology, PBMC express a significant proportion, around 80%, of the genes encoded by the human genome and act as "sentinel" cells capable of reflecting gene expression profiles of internal tissues. [20] In fact, we have previously shown that gene expression of selected key lipid metabolism genes in human PBMC is affected by OW-OB in the same way as in crucial energy homeostatic tissues.…”