Acute, but not chronic, aerobic exercise alters the impact of ex vivo LDL and fatty acid stimulation on monocytes and macrophages from healthy, young adults

BACKGROUND

Elevated low-density lipoprotein (LDL) and triglyceride concentrations are associated with future cardiovascular risk in young adults. Conversely, chronic physical activity is generally accepted to reduce CVD risk. Atherosclerosis is a major underlying cause of CVD, and atherogenesis is mediated by peripheral monocytes and monocyte-derived macrophages. The study aimed to determine if an individual's physical activity level impacts the phenotype of monocytes and monocyte-derived macrophages when stimulated with LDL and fatty acid ex vivo.

METHODS

Peripheral blood mononuclear cells (PBMCs) were obtained from healthy, young adults of differing physical activity levels before and after a single bout of moderate intensity exercise (25 min at 60% of VO_2peak). PBMCs were stimulated with LDL and palmitate ex vivo prior to differentiation into macrophages. Monocyte subset percentages and monocyte-derived macrophage expression of phenotypic (CD86, CD206) and functional (CCR2, ERK 1/2) markers were evaluated by flow cytometry.

RESULTS

Compared to baseline, ex vivo LDL and palmitate stimulation decreased (p = 0.038) non-classical monocyte percentage from 24.7 ± 3.2 to 21.5 ± 2.6% in all participants. When ex vivo lipid stimulation was preceded by acute exercise, non-classical monocyte percentage was similar to baseline levels (p = 0.670, 25.8 ± 2.15%). Macrophage CD86/CD206 was increased from 1.30 ± 0.14 to 1.68 ± 0.19 when preceded by acute exercise in all participants. No differences were observed between participants of differing physical activity levels.

CONCLUSIONS

Findings suggest that acute exercise modulates monocyte phenotype after LDL and palmitate stimulation in a protective manner, however, chronic physical activity does not alter monocyte/macrophage responses to any experimental condition in this population.

LPS differentially affects expression of CD14 and CCR2 in monocyte subsets of Post-STEMI patients with hyperglycemia

AIMS

Following ST-segment elevation myocardial infarction (STEMI), recruitment and activation of monocytes [classical (CD14⁺⁺CD16^-CCR2⁺⁺), intermediate (CD14⁺⁺CD16⁺CCR2⁺), non-classical (CD14^LowCD16⁺⁺CCR2^Low)] are needed for myocardial wound healing. Monocyte surface receptor CC chemokine receptor type 2 (CCR2) is responsible for monocyte chemotaxis to sites of inflammation and the lipopolysaccharide (LPS)-binding protein co-receptor, CD14, is involved in pro-inflammatory monocyte activation. The purpose of this investigation was to determine the effects of ex-vivo LPS activation on monocyte subset CD14 and CCR2 expression in post-STEMI individuals with normal and elevated random blood glucose.

METHODS

Post-STEMI subjects were identified as normal random glucose (NG, <98 mg/dL, n = 13) or impaired random glucose (IG, ≥98 mg/dL, n = 26) and monocytes were analyzed for non-activated and LPS-activated (1 µg/mL for 4 h) CCR2 and CD14 expression.

RESULTS

Non-activated intermediate monocytes from IG showed decreased CD14 expression when compared to NG, which was maintained following LPS-activation. The NG group showed a larger absolute reduction in classical CCR2 expression, leading to a significant difference between NG and IG following LPS-activation.

CONCLUSION

Results suggest a heightened response to pro-inflammatory activation in IG following STEMI, which may impair or delay post-STEMI myocardial healing, and thus increase the incidence of chronic heart failure. NIH 1R34HL121402.

Dual endothelin receptor antagonism increases resting energy expenditure in people with increased adiposity

Increased adiposity is associated with dysregulation of the endothelin system, both of which increase the risk of cardiovascular disease (CVD). Preclinical data indicate that endothelin dysregulation also reduces resting energy expenditure (REE). The objective was to test the hypothesis that endothelin receptor antagonism will increase REE in people with obesity compared with healthy weight individuals. Using a double blind, placebo-controlled, crossover design, 32 participants [healthy weight (HW): n = 16, BMI: 21.3 ± 2.8 kg/m2, age: 26 ± 7 yr and overweight/obese (OB): n = 16, BMI: 33.5 ± 9.5 kg/m2, age: 31 ± 6 yr] were randomized to receive either 125 mg of bosentan (ETA/B antagonism) or placebo twice per day for 3 days. Breath-by-breath gas exchange data were collected and REE was assessed by indirect calorimetry. Venous blood samples were analyzed for concentrations of endothelin-1 (ET-1). Treatment with bosentan increased plasma ET-1 in both OB and HW groups. Within the OB group, the changes in absolute REE (PLA: -77.6 ± 127.6 vs. BOS: 72.2 ± 146.6 kcal/day; P = 0.046). The change in REE was not different following either treatment in the HW group. Overall, absolute plasma concentrations of ET-1 following treatment with bosentan were significantly associated with kcal/day of fat (r = 0.488, P = 0.005), percentage of fat utilization (r = 0.415, P = 0.020), and inversely associated with the percentage of carbohydrates (r = -0.419, P = 0.019), and respiratory exchange ratio (r = -0.407, P = 0.023). Taken together, these results suggest that modulation of the endothelin system may represent a novel therapeutic approach to increase both resting metabolism and caloric expenditure, and reduce CVD risk in people with increased adiposity.NEW & NOTEWORTHY Findings from our current translational investigation demonstrate that dual endothelin A/B receptor antagonism increases total REE in overweight/obese individuals. These results suggest that modulation of the endothelin system may represent a novel therapeutic target to increase both resting metabolism and caloric expenditure, enhance weight loss, and reduce CVD risk in seemingly healthy individuals with elevated adiposity.

Endothelin-1 response to whole-body vibration in obese and normal weight individuals

Upregulation of endothelin-1 (ET-1) is the hallmark of various cardiovascular diseases (CVD). The purpose of the present study was to assess the ET-1 response to an acute bout of whole-body vibration (WBV) in humans and to determine the role of adiposity. Twenty-two participants volunteered for the study; they were grouped into overweight/obese [(OW/OB): n = 11, Age: 33 ± 4 years, Body mass index (BMI): 35 ± 10 kg/m² ] or normal weight [(NW): n = 11, Age: 28 ± 7 years, BMI: 21 ± 2 kg/m² ]. Participants engaged in 10 cycles of WBV exercise (1 cycle = 1 min WBV followed by 30 s of rest). Blood samples were analyzed for ET-1 pre-WBV (PRE), immediately post (POST), 1 h (1H), 3 h (3H), and 24 h (24H) post-WBV. There was a significant time main effect of WBV on circulating ET-1 (F = 12.5, p < 0.001); however, the ET-1 response was similar (F = 0.180, p = 0.677) between groups. Specifically, compared to PRE, a significant increase in ET-1 was observed at 1H (p = 0.017) and 3H (p = 0.025). In addition, concentrations of ET-1 were significantly lower at 24H compared to PRE (p = 0.019), 1H (p < 0.001), and 3H (p < 0.001). Maximal oxygen uptake during WBV was similar between the two groups. Acute WBV resulted in an initial rise in ET-1, followed by a significantly lower ET-1 at 24H in both groups. Findings support the utility of routine WBV exercise to elicit a decrease in ET-1 and improve CVD risk, similar to what has been reported with traditional modes of exercise.

The effects of whole-body vibration amplitude on glucose metabolism, inflammation, and skeletal muscle oxygenation

Whole‐body vibration (WBV) is an exercise mimetic that elicits beneficial metabolic effects. This study aims to investigate the effects of WBV amplitude on metabolic, inflammatory, and muscle oxygenation responses. Forty women and men were assigned to a high (HI; n = 20, Age: 31 ± 6 y) or a low‐amplitude group (LO; n = 20, Age: 33 ± 6 y). Participants engaged in 10 cycles of WBV [1 cycle =1 min of vibration followed by 30 s of rest], while gastrocnemius muscle oxygen consumption (mVO₂) was assessed using near‐infrared spectroscopy (NIRS). Blood samples were collected PRE, POST, 1H, 3Hs, and 24H post‐WBV and analyzed for insulin, glucose, and IL‐6. In the LO group, Homeostatic Model Assessment for Insulin Resistant (HOMA‐IR) at 3 h (0.7 ± 0.2) was significantly lower compared to PRE (1.1 ± 0.2; p = 0.018), POST (1.3 ± 0.3; p = 0.045), 1H (1.3 ± 0.3; p = 0.010), and 24H (1.4 ± 0.2; p < 0.001). In addition, at 24H, HOMA‐IR was significantly lower in the LO when compared to the HI group (LO: 1.4 ± 0.2 vs. HI: 2.2 ± 0.4; p = 0.030). mVO₂ was higher (p = 0.003) in the LO (0.93 ± 0.29 ml/min/100 ml) when compared to the HI group (0.63 ± 0.28 ml/min/100 ml). IL‐6 at 3H (LO: 13.2 ± 2.7 vs. HI: 19.6 ± 4.0 pg·ml⁻¹; p = 0.045) and 24H (LO: 4.2 ± 1.1 vs. HI: 12.5 ± 3.1 pg·ml⁻¹; p = 0.016) was greater in the HI compared to the LO group. These findings indicate that low‐amplitude WBV provides greater metabolic benefits compared to high‐amplitude WBV.

Endothelin receptor blockade blunts the pressor response to acute stress in men and women with obesity

Obesity is associated with dysregulation of the endothelin system. In individuals with obesity, an exaggerated pressor response to acute stress is accompanied by increased circulating endothelin-1 (ET-1). The impact of combined endothelin A/B receptor (ET_A/B) antagonism on the stress-induced pressor response in overweight/obese (OB) individuals is unknown. The objective of this study is to test the hypothesis that treatment with an ET_A/B antagonist (bosentan) would reduce the stress-induced pressor response and arterial stiffness in overweight/obese compared with normal weight (NW) individuals. Forty participants [normal weight (NW): n = 20, body mass index (BMI): 21.7 ± 2.4 kg/m² and overweight/obese (OB): n = 20, BMI: 33.8 ± 8.2 kg/m²] were randomized to placebo or 125 mg of bosentan twice a day (250 mg total) for 3 days. Hemodynamics were assessed before, during, and after a cold pressor test (CPT). Endothelin-1 was assessed at baseline and immediately after CPT. Following a washout period, the same protocol was repeated with the opposite treatment. The change from baseline in mean arterial pressure (MAP) during CPT following bosentan was significantly lower (P = 0.039) in the OB group than in the NW group (OB: 28 ± 12 vs. NW: 34 ± 15 mmHg). These results suggest that ET_A/B antagonism favorably blunts the pressor response to acute stress in overweight/obese individuals.NEW & NOTEWORTHY Findings from our current translational investigation demonstrate that dual endothelin A/B receptor antagonism blunts the pressor response to acute stress in overweight/obese individuals. These results suggest that modulation of the endothelin system may represent a novel therapeutic target to reduce cardiovascular disease (CVD) risk by blunting the stress response in overweight/obese individuals.

Impact of physical activity on monocyte subset CCR2 expression and macrophage polarization following moderate intensity exercise

Coronary artery disease (CAD) is an immune-mediated disease in which CCR2 attracts classical, intermediate, and non-classical monocytes to the arterial intima where they differentiate to macrophages. Balance between pro-inflammatory M1 and anti-inflammatory M2 macrophages contributes to CAD prevention. Moderate to vigorous intensity physical activity (MVPA) elicits an immune response and reduces the incidence of CAD, however, the impact of prior MVPA on monocyte subset CCR2 expression and macrophage polarization following acute exercise is unknown.

Purpose

To determine the impact of physical activity status on monocyte subset CCR2 surface expression and macrophage polarization in response to an acute bout of moderate intensity cycle ergometry.

Methods

24 healthy women and men (12 high physically active [HIACT]: ≥1500 METmin/wk MVPA & 12 low physically active [LOACT]: <600 METmin/wk MVPA) underwent an acute moderate intensity (60% VO2peak) bout of cycle ergometry for 30 ​min. Blood samples were collected prior to (PRE), immediately (POST), 1 ​h (1H), and 2 ​h (2H) following exercise. Monocyte CCR2 and macrophage CD86 (M1) and CD206 (M2) were analyzed by flow cytometry.

Results

Intermediate monocyte CCR2 decreased in response to exercise in the HIACT group (PRE: 11409.0 ​± ​1084.0 vs. POST: 9524.3 ​± ​1062.4; p ​= ​0.034). Macrophage CD206 was lower in the LOACT compared to the HIACT group at 1H (HIACT: 67.2 ​± ​5.6 vs. LOACT: 50.1 ​± ​5.2%; p ​= ​0.040). Macrophage CD206 at 1H was associated with both PRE (r ​= ​0.446, p ​= ​0.043) and POST (r ​= ​0.464, p ​= ​0.034) non-classical monocyte CCR2.

Conclusion

These data suggest that regular moderate to vigorous physical activity positively impacts both monocytes and macrophages following acute moderate intensity exercise and that this impact may contribute to the prevention of coronary artery disease.

Whole body vibration elicits differential immune and metabolic responses in obese and normal weight individuals

Traditional aerobic exercise reduces the risk of developing chronic diseases by inducing immune, metabolic, and myokine responses. Following traditional exercise, both the magnitude and time-course of these beneficial responses are different between obese compared to normal weight individuals. Although obesity may affect the ability to engage in traditional exercise, whole body vibration (WBV) has emerged as a more tolerable form of exercise . The impact of WBV on immune, metabolic, and myokine responses as well as differences between normal weight and obese individuals, however, is unknown.

Purpose

To determine if WBV elicits differential magnitudes and time-courses of immune, metabolic, and myokine responses between obese and normal weight individuals.

Methods

21 participants [Obese (OB): n = 11, Age: 33 ± 4 y, percent body fat (%BF): 39.1 ± 2.4% & Normal weight (NW) n = 10, Age: 28 ± 8 y, %BF: 17.4 ± 2.1%] engaged in 10 cycles of WBV exercise [1 cycle = 1 min of vibration followed by 30 s of rest]. Blood samples were collected pre-WBV (PRE), immediately (POST), 3 h (3H), and 24 h (24H) post-WBV and analyzed for leukocytes, insulin, glucose, and myokines (IL-6, decorin, myostatin).

Results

The peak (3H) percent change in neutrophil counts (OB: 13.9 ± 17.4 vs. NW: 47.2 ± 6.2%Δ; p = 0.007) was different between groups. The percent change in neutrophil percentages was increased in NW (POST: -1.6 ± 2.0 vs. 3H: 13.0 ± 7.2%Δ, p = 0.019) but not OB (p > 0.05). HOMA β-cell function was increased at 24H (PRE: 83.4 ± 5.4 vs. 24H: 131.0 ± 14.1%; p = 0.013) in NW and was not altered in OB (p > 0.05). PRE IL-6 was greater in OB compared to NW (OB: 2.7 ± 0.6 vs. NW: 0.6 ± 0.1 pg/mL; p = 0.011); however, the percent change from PRE to peak (3H) was greater in NW (OB: 148.1 ± 47.9 vs. NW: 1277.9 ± 597.6 %Δ; p = 0.035). Creatine kinase, decorin, and myostatin were not significantly altered in either group (p > 0.05).

Conclusion

Taken together, these data suggest that acute whole body vibration elicits favorable immune, metabolic, and myokine responses and that these responses differ between obese and normal weight individuals.