Direct assessment of leukocyte signalling and cytokine secretion reveals exercise intensity-dependent reductions in anti-inflammatory cytokine action.

Circulating interleukin (IL)-6 and IL-10 concentrations are widely used to evaluate the anti-inflammatory effects of exercise but do not capture cytokine action at the cellular level. Whether and how acute exercise impacts anti-inflammatory cytokine action in humans is unknown. To determine how exercise intensity and pattern impact IL-6 and IL-10 action in blood leukocytes, 16 active adults (eight males/eight females; age: 30 ± 3 years; body mass index: 22.8 ± 2.3 kg/m2; V ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ : 51 ± 6 mL/kg/min) completed a no-exercise control condition (CTL) or isocaloric bouts of cycling performed below (moderate continuous exercise; MCE) or above (heavy continuous or heavy intermittent exercise; HCE or HIE, respectively) lactate threshold. Venous blood (before, after, 30 min after and 90 min after exercise) was analysed for immune cell subpopulations, plasma cytokine concentrations, anti-inflammatory cytokine action and monocyte phenotype. Exercise induced rapid leukocytosis (P < 0.001) and increased plasma IL-6 (P < 0.001), IL-10 (P = 0.0145) and tumour necrosis factor-⍺ (TNF-⍺) (P = 0.0338) concentrations in an intensity-dependent manner (HCE and/or HIE vs. CTL). These systemic changes coincided with a diminished ability of IL-10/6 to phosphorylate STAT3 (P < 0.001) and inhibit TNF-⍺ secretion (P = 0.0238) in blood leukocytes following HCE and HIE. Monocyte polarization experiments revealed lower CD80 [MCE (P = 0.0933) and HIE (P = 0.0187) vs. CTL] and a tendency for higher CD163 expression (HCE vs. CTL, P = 0.0985), suggesting that hyporesponsiveness to anti-inflammatory cytokine action does not impede the ability of exercise to promote an anti-inflammatory monocyte phenotype. These findings provide novel insights into the immunomodulatory effects of exercise in humans and highlight the importance of directly measuring cellular cytokine action when evaluating the anti-inflammatory effects of exercise. KEY POINTS: Circulating cytokine concentrations are frequently used to evaluate the anti-inflammatory effects of exercise but may not capture changes in cytokine action occurring at the cellular level. We directly assessed anti-inflammatory cytokine action - measured using a combination of intracellular signalling and cytokine secretion ex vivo - in distinct immune cell subpopulations after acute calorie-matched exercise bouts differing in intensity and pattern. Anti-inflammatory cytokine action was blunted following higher intensity exercise despite corresponding increases in circulating cytokine concentrations and immune cell counts. Changes in cytokine action were not explained by changes in cytokine receptor expression on circulating immune cells. Our findings provide new insights into the immunomodulatory effects of exercise in humans and highlight the importance of directly measuring cellular cytokine action when evaluating the anti-inflammatory effects of exercise.

Effect of the ketone beta-hydroxybutyrate on markers of inflammation and immune function in adults with type 2 diabetes.

Pre-clinical and cell culture evidence supports the role of the ketone beta-hydroxybutyrate (BHB) as an immunomodulatory molecule that may inhibit inflammatory signalling involved in several chronic diseases such as type 2 diabetes (T2D), but studies in humans are lacking. Therefore, we investigated the anti-inflammatory effect of BHB in humans across three clinical trials. To investigate if BHB suppressed pro-inflammatory cytokine secretion, we treated LPS-stimulated leukocytes from overnight-fasted adults at risk for T2D with BHB (Study 1). Next (Study 2), we investigated if exogenously raising BHB acutely in vivo by ketone monoester supplementation (KME) in adults with T2D would suppress pro-inflammatory plasma cytokines. In Study 3, we investigated the effect of BHB on inflammation via ex vivo treatment of LPS-stimulated leukocytes with BHB and in vivo thrice-daily pre-meal KME for 14 days in adults with T2D. Ex vivo treatment with BHB suppressed LPS-stimulated IL-1ß, TNF-α, and IL-6 secretion and increased IL-1RA and IL-10 (Study 1). Plasma IL-10 increased by 90 min following ingestion of a single dose of KME in T2D, which corresponded to peak blood BHB (Study 2). Finally, 14 days of thrice-daily KME ingestion did not significantly alter plasma cytokines or leukocyte subsets including monocyte and T-cell polarization (Study 3). However, direct treatment of leukocytes with BHB modulated TNF-α, IL-1ß, IFN-γ, and MCP-1 secretion in a time- and glucose-dependent manner (Study 3). Therefore, BHB appears to be anti-inflammatory in T2D, but this effect is transient and is modulated by the presence of disease, glycaemia, and exposure time.

Sex differences in IL-10's anti-inflammatory function: greater STAT3 activation and stronger inhibition of TNF-α production in male blood leukocytes ex vivo.

Interleukin-10 (IL-10) inhibits proinflammatory cytokine production in blood leukocytes-an effect mediated by signal transducer and activator of transcription 3 (STAT3) activation. To examine potential sex-based differences in IL-10's anti-inflammatory function, we treated whole blood from healthy males and females (n = 16 participants of each sex; age: 28 ± 6 yr; body mass index: 23.5 ± 2.3 kg/m2) with increasing concentrations of IL-10 (1-100 ng/mL) and quantified changes in phosphorylated STAT3 (pSTAT3) in CD14+ monocytes and CD4+ lymphocytes via flow cytometry. In parallel, liposaccharide (LPS)-stimulated whole blood cultures were used to assess sex-based differences in IL-10's ability to inhibit tumor necrosis factor (TNF)-α production. IL-10 concentration dependently increased pSTAT3 median fluorescent intensity (MFI) in CD14+ and CD4+ cells (main effects of concentration, P < 0.01) with males exhibiting larger changes in pSTAT3 MFI in both cell types (main effects of sex, P < 0.01). Accordingly, IL-10-mediated inhibition of TNF-α production was more pronounced in males (main effect of sex, P < 0.01) with changes in other monocyte-derived cytokines (IL-1ß, IL-1RA, and IL-15) also supporting a sexual dimorphism in IL-10 action (P < 0.05). These sex-based differences were not explained by differences in circulating plasma IL-10 concentrations, basal IL-10 receptor expression in unstimulated CD14+ and CD4+ cells, nor the basal expression of IL-10 signaling proteins (STAT3, SHIP1, and p38 MAPK) in unstimulated peripheral blood mononuclear cells. We conclude that IL-10's anti-inflammatory function differs between male and female blood leukocytes ex vivo. This sexual dimorphism should be considered in future work investigating IL-10's anti-inflammatory action in humans as it may represent a mechanism contributing to sex differences in overall immune function.

Sprint exercise snacks: a novel approach to increase aerobic fitness.

PURPOSE: Sprint interval training (SIT), involving brief intermittent bursts of vigorous exercise within a single training session, is a time-efficient way to improve cardiorespiratory fitness (CRF). It is unclear whether performing sprints spread throughout the day with much longer (≥ 1 h) recovery periods can similarly improve CRF, potentially allowing individuals to perform "sprint snacks" throughout the day to gain health benefits. METHODS: Healthy, young, inactive adults (~ 22 years, peak oxygen uptake [VO2peak] ~ 35 ml kg- 1 min- 1) were randomly assigned to one of two groups and performed 18 training sessions over 6 wks. Sprint snacks (SS) involved 3 × 20-s 'all out' cycling bouts separated by 1-4-h rest (n = 12, 7 females). Traditional SIT involved 3 × 20-s bouts interspersed with 3-min rest within a 10-min training session (n = 16, 7 females). The primary outcome was CRF determined by a VO2peak test conducted before and after training. Secondary outcomes included a 150 kJ cycling time trial and exercise enjoyment. RESULTS: Absolute VO2peak increased by ~ 6% after SIT and ~ 4% for SS (main effect of time P = 0.002) with no difference between groups (group × time interaction, P = 0.52). 150 kJ time trial performance improved by ~ 13% in SIT and ~ 9% in SS (main effect of time, P < 0.001) with no difference between groups (group × time interaction, P = 0.36). CONCLUSION: CRF was similarly increased by a protocol involving sprint snacks spread throughout the day and a traditional SIT protocol in which bouts were separated by short recovery periods within a single training session.

Examining the Effect of Consuming C8 Medium-Chain Triglyceride Oil for 14 Days on Markers of NLRP3 Activation in Healthy Humans.

Chronic, low-grade inflammation is associated with the development of numerous diseases and is mediated in part by overactivation of the NLRP3 inflammasome. The ketone body beta-hydroxybutyrate (ßHB) suppresses the NLRP3 inflammasome and alters intracellular signalling pathways in vitro and in animal models; however, this effect has not yet been shown in vivo in humans. The purpose of this single-arm pilot trial was to determine if consuming 15 mL of C8 medium-chain triglyceride (trioctanoin; MCT) oil, which induces mild elevation of ßHB, twice daily (30 mL total) for 14 days would suppress markers of NLRP3 inflammasome activation in young, healthy humans while following their habitual diet. Consuming a single dose of 15 mL of C8 MCT oil significantly raised blood ßHB from fasting at 60 minutes and 120 minutes post ingestion (both P < 0.05). However, consumption of C8 MCT oil for 14 days did not impact markers of monocyte NLRP3 inflammasome activation compared to baseline. Specifically, caspase-1 activation and secretion of its downstream product interleukin (IL)-1ß were unchanged following 14 days of C8 MCT oil supplementation when measured in unstimulated and LPS-stimulated whole blood cultures (all P > 0.05). Acetylation of histone H3 on the lysine residue 9 was unchanged (P < 0.05) and acetylation of lysine residue 14 was decreased (P < 0.05) following 14 days of supplementation. Thus, adding twice daily C8 MCT oil supplementation to the habitual diet of young, healthy humans does not appear to suppress NLRP3 inflammasome activation.

Impact of an Acute Bout of Submaximal Aerobic Exercise on Circulating Leukocytes in Individuals with Spinal Cord Injury.

Individuals with spinal cord injury (SCI) may experience cardiovascular, musculoskeletal and organ function dysregulation. Sequelae include reduced catecholamine secretion and attenuated immune responses which may impact exercise-induced leukocytosis. The purpose of this study was to characterize major leukocyte subtypes following 30 minutes of acute, submaximal aerobic exercise, in line with updated international SCI exercise guidelines for adults. It was hypothesized that exercise would increase major leukocyte subtypes when compared to fasted baseline. Eight participants with SCI (incomplete n = 6; complete n = 2) completed a 30-minute bout of aerobic exercise on an arm cycle ergometer at 60% of their peak power output followed by 90 minutes of recovery, or a 2-hour seated control condition, in a randomized crossover design, separated by 7-14 days. Blood samples were taken at baseline, post exercise, and 90 minutes after exercise (with time matched control). Leukocyte subtypes were analyzed via flow cytometry and plasma catecholamines by ELISA. Several leukocytes increased from pre- to post-exercise (time X condition interaction; all P < 0.05; mean ± SD), including CD3+ Lymphocytes (19 ± 16%), CD4+ T helper (16 ± 13%), CD8+ T cytotoxic (24 ± 23%), CD3+/CD56+ natural killer T (31 ± 34%), and CD3-/CD56+ natural killer (63 ± 82%). CD16+/CD14dim monocytes decreased by 27 ± 38% following exercise to 90 minutes post-exercise. No changes were observed for catecholamines for either condition. Thirty minutes of acute submaximal aerobic exercise sufficiently increased most lymphocyte subsets with effector functions, while leading to decreased proinflammatory monocytes during the recovery phase. This exercise duration and intensity appear to be an appropriate option for modulating circulating immune cells in individuals with SCI.

Acute submaximal exercise does not impact aspects of cognition and BDNF in people with spinal cord injury: A pilot study.

Objective: To investigate the effect of acute submaximal exercise, based on the spinal cord injury (SCI) Exercise Guidelines, on cognition and brain-derived neurotrophic factor (BDNF) in people with SCI. Design: Eight adults (7 males) with traumatic SCI volunteered in this pre-registered pilot study. In randomized order, participants completed submaximal intensity arm cycling (60% of measured peak-power output at 55-60 rpm) for 30 min or time-matched quiet rest (control condition) on separate days. Blood-borne BDNF was measured in serum and plasma at pre-intervention, 0 min and 90 min post-intervention. Cognition was assessed using the Stroop Test and Task-Switching Test on an electronic tablet pre- and 10 min post-intervention. Results: Submaximal exercise had no effect on plasma [F(2,12) = 1.09; P = 0.365; η² = 0.069] or serum BDNF [F(2,12) = 0.507; P = 0.614; η² = 0.024] at either 0 min or 90 min post-intervention. Similarly, there was no impact of exercise on either Stroop [F(1,7) = 2.05; P = 0.195; η² = 0.065] or Task-Switching performance [F(1,7) = 0.016; P = 0.903; η² < 0.001] compared to the control condition. Interestingly, there was a positive correlation between years since injury and resting levels of both plasma (r = 0.831; P = 0.011) and serum BDNF (r = 0.799; P = 0.023). However, there was not relationship between years since injury and the BDNF response to exercise. Conclusions: Acute guideline-based exercise did not increase BDNF or improve aspects of cognition in persons with SCI. This work establishes a foundation for continued investigations of exercise as a therapeutic approach to promoting brain health among persons with SCI.

Spinal cord injury impairs cardiac function due to impaired bulbospinal sympathetic control.

Spinal cord injury chronically alters cardiac structure and function and is associated with increased odds for cardiovascular disease. Here, we investigate the cardiac consequences of spinal cord injury on the acute-to-chronic continuum, and the contribution of altered bulbospinal sympathetic control to the decline in cardiac function following spinal cord injury. By combining experimental rat models of spinal cord injury with prospective clinical studies, we demonstrate that spinal cord injury causes a rapid and sustained reduction in left ventricular contractile function that precedes structural changes. In rodents, we experimentally demonstrate that this decline in left ventricular contractile function following spinal cord injury is underpinned by interrupted bulbospinal sympathetic control. In humans, we find that activation of the sympathetic circuitry below the level of spinal cord injury causes an immediate increase in systolic function. Our findings highlight the importance for early interventions to mitigate the cardiac functional decline following spinal cord injury.

The Impact of Sub-maximal Exercise on Neuropathic Pain, Inflammation, and Affect Among Adults With Spinal Cord Injury: A Pilot Study.

Introduction: Persons with spinal cord injury (SCI) often report high levels of neuropathic pain (NP) and poor well-being, which may result from increased inflammation. This study examined the impact of sub-maximal aerobic exercise on NP, inflammation and psychological affect among adults with SCI. Methods: Eight active adults with tetraplegia (n-4, AIS A-C) and paraplegia (n = 4, AIS A-C) performed 30-min of arm-crank aerobic exercise and reported their ratings of perceived exertion (RPE) each minute. Measures of NP, affect, and inflammatory cytokines (IL-6, IL-10, IL-1ra, TNF-α) were taken pre-(T0), immediately post-(T1), and 90-min post-exercise (T2). Results: NP decreased between T0 and T1 for tetraplegics (-60%, d = 0.47; CI = -0.32, 2.02) and paraplegics (-16%, d = 0.15; CI = -0.30, 0.90). Correlations between change in cytokines and change in NP were medium-to large for tetraplegics (rs ranged from -0.820 to 0.965) and paraplegics (rs ranged from -0.598 to 0.833). However, the pattern of correlations between change in cytokines and affect was inconsistent between groups. Lower baseline levels of IL-1ra predicted greater decreases in NP immediately post-exercise (r = 0.83, p = 0.01). Conclusion: Sub-maximal exercise can positively impact NP for some persons with SCI. Further experimental research should identify the optimal exercise intensity to reduce NP for persons with SCI, in addition to understanding biomarkers which may predict changes in NP. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT03955523.

The effects of a high-fat/high-carbohydrate meal on leukocyte populations in adults with chronic spinal cord injury.

STUDY DESIGN: Secondary analysis of aggregated case series data. OBJECTIVES: To examine the effects of a high-fat/high-carbohydrate meal on leukocyte populations in adults with a chronic SCI. SETTING: University-based laboratories in British Columbia, Canada. METHODS: Ten individuals (M = 9) with a traumatic SCI (>1-year post-injury; M = 15.5 years; n = 2 sensory complete, n = 7 motor complete) participated in this study. Participants arrived fasted (≥12 h) prior to both the control (quiet sitting, no food/drink) and experimental meal conditions (high-fat/high-carb meal: 880 kcal, 52 g fat, 73 g carbohydrates, 29 g protein). Blood samples were taken in the fasted state and at 120-min post-meal/baseline in both conditions. Immune cell counts were assessed using multi-color flow cytometry. RESULTS: A significant time × condition interaction effect was seen in CD3+, CD4+, and CD8+ T cells as well as CD56+ and CD3+/CD56+ natural killer (NK) cells (p < 0.05). CD14+/CD16+ monocytes and CD19+ B cells approached a significant time × condition interaction (p < 0.07). A main effect of time was observed in CD19+ B cells (p < 0.05). Cell counts for T-lymphocytes and NK cells followed the general trend of an increase in the control condition from baseline to 120-min with no change observed following the experimental meal condition. CONCLUSIONS: Following the HFHC meal, immune cells did not show the same general increase observed following the control condition. Future research is needed to determine if there are any potential consequences of these immune cell responses in immunosuppressed populations and if other factors (e.g., diurnal variation) might influence immune cell response.

How credit scores can make a difference for your revenue cycle.

Questions an organization should consider before implementing credit scoring include: What action will be taken once a score is obtained? Should the score impact the workflow? Are the appropriate tools available to alter the workflow? How will accounts receivable staff be redirected or allocated? What is the risk tolerance for scoring mistakes?