Effects of an exercise challenge on mobilization and surface marker expression of monocyte subsets in individuals with normal vs. elevated blood pressure

Abstract

High blood pressure (BP) and monocyte activation are associated with atherogenic processes. Especially, CD16 expressing monocytes are shown to be activated in many inflammatory conditions but their characteristics in hypertension is unknown. We compared CD16 ++ , CD16 + and CD16 − monocyte populations and their cellular adhesion molecule (CAM), chemokine receptor, and activation marker expression in response to a moderate 20-min treadmill exercise bout at 65-70% VO 2peak in 44 participants with elevated (EBP) or normal BP (NBP). Blood was drawn before, immediately after, and 10min after exercise. Phenotyping of monocytes and detection of surface markers were done by flow cytometry. Monocyte subset by exercise [pre, post, 10-min post] repeated measures ANOVA and group [EBP vs. NBP] by exercise repeated measures of ANCOVA with age, BMI, and fitness as covariates were employed. Circulating numbers of all the three monocyte subsets increased after exercise (p< 0.001), with the largest % increase for CD16 + CD14 ++ . Percents of CD16 ++ CD14 + and CD16 + CD14 ++ increased, whereas % CD16 − CD14 ++ decreased (p< 0.001). Also, pre to post exercise changes in CD62L, CD11b, CXCR2, and HLA-DR expression were different among the monocyte subsets (p's< 0.001). BP status did not significantly affect monocyte subset trafficking, although post-exercise changes in CD62L and CXCR2 levels were greater in EBP individuals (p< 0.05). We conclude that exercise leads to a different mobilization among monocyte subsets based on CD16 expression. Individuals with high BP showed greater responses to a physical challenge in some monocyte chemokine receptors and selectins, but its clinical implications need further examination.

Expression of intracellular cytokines, HSP72, and apoptosis in monocyte subsets during exertional heat stress in trained and untrained individuals

“…As previously suggested (76), it does not appear that circulatory IL-6 or IL-1ra increases originate from peripheral monocyte subsets; in fact, a reduction in protein content was observed during EHS, possibly reflecting the inflammatory status of these cells. In contrast, minimal changes in intracellular IL-10 were observed in the present study, which may be due to signaling kinetics and/or current gating profiles, since it has recently been shown that the inflammatory subset can be subdivided into CD14 Bri CD16 ϩ and CD14 Dim CD16 ϩ (31,72), where CD14 Bri CD16 ϩ and CD14 Dim CD16 ϩ are the major producers of IL-10 and TNF-␣, respectively (72).…”

“…Normally comprising Ͻ10% of all circulating monocytes, the inflammatory subset in the peripheral blood has been shown to expand with exercise (31,78) and is associated with various inflammatory disorders (29,30,82). Elevations in body temperature (32) and secreted levels of TNF-␣ (71) also have been correlated with inflammatory subset expansion; however, to our knowledge, no data exist relative to exertional heat stress (EHS).…”

“…At rest, a majority of the CD14 ϩ CD16 ϩ monocytes are not present in the peripheral circulation but reside in the marginal pool and are released into the peripheral circulation via catecholaminemediated sympathetic mechanisms (78). The time course of peripheral blood inflammatory monocyte expansion during disease (Ͼ50%) (25) has been found to follow systemic cytokine appearance (7,91); however, with physical stress, an immediate mobilization of CD14 ϩ CD16 ϩ cells from the marginal pool is observed (31,78). EHS elicited a similar increase in CD14 ϩ CD16 ϩ subsets, with a greater increase observed in TR subjects.…”

HLA‐DR expression and differential trafficking of monocyte subsets following low to intermediate risk surgery*

“…Numerous flow cytometric strategies have been previously employed to divide human monocytes into distinct subsets based upon their expression of a variety of cell surface markers [19][20][21][22][23][24]. Although the gating strategy certainly impacts upon the results obtained, there is currently no consensus amongst investigators.…”

“…Blood monocytes consist of a heterogeneous cell population of differing maturity and phenotype with potentially distinct functional capabilities [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. In humans, monocyte subpopulations are classified on the basis of expression levels of leukocyte surface protein CD 14 (CD = Cluster of Differentiation) and CD16, and two main subsets are usually identified: CD14 high monocytes; and CD14 low CD16+ monocytes.…”