Monocyte Adhesion Molecule Expression Following an Acute Bout of Moderate Intensity Cycling

Abstract

Monocyte adhesion to the endothelium is a key step in the development of atherosclerosis. It is well established that higher CV fitness is associated with a reduced risk for CV disease. PURPOSE: To investigate the impact of fitness on monocyte surface receptor expression of CD11c and VLA4 following an acute bout of exercise. METHODS: 9 fit (VO2 peak; males: ≥45 mLO2/kg/min, females: ≥35 mLO2/kg/min) and 13 unfit (VO2 peak; males: <40 mLO2/kg/min, females: <30 mLO2/kg/min) subjects performed 30 min of moderate intensity (60% VO2 peak) cycling. Blood samples were obtained pre-exercise, immediately, and 1 h post-exercise. Monocytes were stained with antibodies against CD14, CD16, VLA4, and CD11c and were analyzed via flow cytometry. A mixed between-within repeated measures ANOVA was used to determine the impact of fitness on VLA4 and CD11c following a submaximal bout of exercise. RESULTS: There were no significant between-subjects main effect for groups in either of the monocyte subsets (p>0.083). A main effect for time was significant in VLA4 (p=0.004) and CD11c (p=0.014) expression in non-classical and classical monocytes, respectively. A profile plot suggested that VLA4 was increased 1 h post-exercise and CD11c was reduced immediately post-exercise. CONCLUSIONS: Monocyte receptor expression does not appear to be impacted by physical fitness in young, apparently healthy adults. Nevertheless, an acute bout of cycling altered the expression level of monocyte adhesion molecules to varying degrees depending on the specific monocyte subset.