The stress response in human peripheral mononuclear cells is related to aerobic fitness and Body Mass Index

BACKGROUND: Dysfunctional HSP70 control has been shown in disease states associated with low cardiovascular fitness (CVF) and obesity. It is unknown if these factors impact HSP70 expression in response to stress. The purpose of this study is to determine if HSP70 activation in PBMCs is altered among overweight humans with low CVF. METHODS: Human PBMCs were isolated from aerobically trained (fit) and untrained human (unfit) subjects after an overnight fast. PBMCs were plated at 2×106 cells/mL and incubated overnight at 37 °C. The following day, plates were separated into the two groups: control (37 °C), heat (41 °C, 90 min). HSP70 protein expression was measured by Western blot analysis. A multiplex bead assay was used to measure cell supernatant levels of TNF-α, IL-6, IL-1β, and IL-10. RESULTS: There was no difference in HSP70 levels at 37°C between fit and unfit groups. Fit individuals showed a greater upregulation of HSP70 after heat (41°C) compared to unfit (1.95±0.83 vs. 0.95±0.45, P<0.05). The relationship between HSP70 and estimated VO₂max was linear while HSP70 and BMI were inversely associated (r²=0.28, r²=-0.258, P<0.05, respectively). TNF-α levels significantly increased in unfit PBMC media after heat stress (41°C) compared to 37°C (5.85±3.33 vs. 3.18±2.11 pg/mL, P<0.05). CONCLUSIONS: These results indicate that both aerobic fitness and BMI influence HSP70 regulation in PBMCs and may further alter low grade inflammation.