Exercise-induced ß2-adrenergic receptor activation enhances the anti-leukemic activity of expanded γδ T-Cells via DNAM-1 upregulation and PVR/Nectin-2 recognition.

Exercise mobilizes cytotoxic lymphocytes to blood which may allow superior cell products to be manufactured for cancer therapy. Gamma-Delta (γδ) T-cells have shown promise for treating solid tumors, but there is a need to increase their potency against hematologic malignancies. Here, we show that human γδ T-cells mobilized to blood in response to just 20-minutes of graded exercise have surface phenotypes and transcriptomic profiles associated with cytotoxicity, adhesion, migration and cytokine signaling. Following 14-days ex vivo expansion with zoledronic acid and interleukin (IL)-2, exercise mobilized γδ T-cells had surface phenotypes and transcriptomic profiles associated with enhanced effector functions, and demonstrated superior cytotoxic activity against multiple hematologic tumors in vitro, and in vivo in leukemia bearing xenogeneic mice. Infusing humans with the ß1+ß2-agonist isoproterenol and administering ß1 or ß1+ß2 antagonists prior to exercise revealed these effects to be ß2-adrenergic receptor (AR) dependent. Antibody blocking of DNAM-1 on expanded γδ T-cells, as well as the DNAM-1 ligands PVR and Nectin-2 on leukemic targets, abolished the enhanced anti-leukemic effects of exercise. These findings provide a mechanistic link between exercise, ß2-AR activation, and the manufacture of superior γδ T-cell products for adoptive cell therapy against hematological malignancies.

Parotid glands have a dysregulated immune response following radiation therapy.

Head and neck cancer treatment often consists of surgical resection of the tumor followed by ionizing radiation (IR), which can damage surrounding tissues and cause adverse side effects. The underlying mechanisms of radiation-induced salivary gland dysfunction are not fully understood, and treatment options are scarce and ineffective. The wound healing process is a necessary response to tissue injury, and broadly consists of inflammatory, proliferative, and redifferentiation phases with immune cells playing key roles in all three phases. In this study, select immune cells were phenotyped and quantified, and certain cytokine and chemokine concentrations were measured in mouse parotid glands after IR. Further, we used a model where glandular function is restored to assess the immune phenotype in a regenerative response. These data suggest that irradiated parotid tissue does not progress through a typical inflammatory response observed in wounds that heal. Specifically, total immune cells (CD45+) decrease at days 2 and 5 following IR, macrophages (F4/80+CD11b+) decrease at day 2 and 5 and increase at day 30, while neutrophils (Ly6G+CD11b+) significantly increase at day 30 following IR. Additionally, radiation treatment reduces CD3- cells at all time points, significantly increases CD3+/CD4+CD8+ double positive cells, and significantly reduces CD3+/CD4-CD8- double negative cells at day 30 after IR. Previous data indicate that post-IR treatment with IGF-1 restores salivary gland function at day 30, and IGF-1 injections attenuate the increase in macrophages, neutrophils, and CD4+CD8+ T cells observed at day 30 following IR. Taken together, these data indicate that parotid salivary tissue exhibits a dysregulated immune response following radiation treatment which may contribute to chronic loss of function phenotype in head and neck cancer survivors.

Granzyme F: Exhaustion Marker and Modulator of Chimeric Antigen Receptor T Cell-Mediated Cytotoxicity.

Granzymes are a family of proteases used by CD8 T cells to mediate cytotoxicity and other less-defined activities. The substrate and mechanism of action of many granzymes are unknown, although they diverge among the family members. In this study, we show that mouse CD8+ tumor-infiltrating lymphocytes (TILs) express a unique array of granzymes relative to CD8 T cells outside the tumor microenvironment in multiple tumor models. Granzyme F was one of the most highly upregulated genes in TILs and was exclusively detected in PD1/TIM3 double-positive CD8 TILs. To determine the function of granzyme F and to improve the cytotoxic response to leukemia, we constructed chimeric Ag receptor T cells to overexpress a single granzyme, granzyme F or the better-characterized granzyme A or B. Using these doubly recombinant T cells, we demonstrated that granzyme F expression improved T cell-mediated cytotoxicity against target leukemia cells and induced a form of cell death other than chimeric Ag receptor T cells expressing only endogenous granzymes or exogenous granzyme A or B. However, increasing expression of granzyme F also had a detrimental impact on the viability of the host T cells, decreasing their persistence in circulation in vivo. These results suggest a unique role for granzyme F as a marker of terminally differentiated CD8 T cells with increased cytotoxicity, but also increased self-directed cytotoxicity, suggesting a potential mechanism for the end of the terminal exhaustion pathway.

COVID-19 vaccination produces exercise-responsive SARS-CoV-2 specific T-cells regardless of infection history.

BACKGROUND: The mobilization and redistribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) specific T-cells and neutralizing antibodies (nAbs) during exercise is purported to increase immune surveillance and protect against severe coronavirus disease 2019 (COVID-19). We sought to determine if COVID-19 vaccination would elicit exercise-responsive SARS-CoV-2 T-cells and transiently alter nAb titers. METHODS: Eighteen healthy participants completed a 20-min bout of graded cycling exercise before and/or after receiving a COVID-19 vaccine. All major leukocyte subtypes were enumerated before, during, and after exercise by flow cytometry, and immune responses to SARS-CoV-2 were determined using whole blood peptide stimulation assays, T-cell receptor (TCR)-ß sequencing, and SARS-CoV-2 nAb serology. RESULTS: COVID-19 vaccination had no effect on the mobilization or egress of major leukocyte subsets in response to intensity-controlled graded exercise. However, non-infected participants had a significantly reduced mobilization of CD4+ and CD8+ naive T-cells, as well as CD4+ central memory T-cells, after vaccination (synthetic immunity group); this was not seen after vaccination in those with prior SARS-CoV-2 infection (hybrid immunity group). Acute exercise after vaccination robustly mobilized SARS-CoV-2 specific T-cells to blood in an intensity-dependent manner. Both groups mobilized T-cells that reacted to spike protein; however, only the hybrid immunity group mobilized T-cells that reacted to membrane and nucleocapsid antigens. nAbs increased significantly during exercise only in the hybrid immunity group. CONCLUSION: These data indicate that acute exercise mobilizes SARS-CoV-2 specific T-cells that recognize spike protein and increases the redistribution of nAbs in individuals with hybrid immunity.

Human lymphocytes mobilized with exercise have an anti-tumor transcriptomic profile and exert enhanced graft-versus-leukemia effects in xenogeneic mice.

Background: Every bout of exercise mobilizes and redistributes large numbers of effector lymphocytes with a cytotoxic and tissue migration phenotype. The frequent redistribution of these cells is purported to increase immune surveillance and play a mechanistic role in reducing cancer risk and slowing tumor progression in physically active cancer survivors. Our aim was to provide the first detailed single cell transcriptomic analysis of exercise-mobilized lymphocytes and test their effectiveness as a donor lymphocyte infusion (DLI) in xenogeneic mice engrafted with human leukemia. Methods: Peripheral blood mononuclear cells (PBMCs) were collected from healthy volunteers at rest and at the end of an acute bout of cycling exercise. Flow cytometry and single-cell RNA sequencing was performed to identify phenotypic and transcriptomic differences between resting and exercise-mobilized cells using a targeted gene expression panel curated for human immunology. PBMCs were injected into the tail vein of xenogeneic NSG-IL-15 mice and subsequently challenged with a luciferase tagged chronic myelogenous leukemia cell line (K562). Tumor growth (bioluminescence) and xenogeneic graft-versus-host disease (GvHD) were monitored bi-weekly for 40-days. Results: Exercise preferentially mobilized NK-cell, CD8+ T-cell and monocyte subtypes with a differentiated and effector phenotype, without significantly mobilizing CD4+ regulatory T-cells. Mobilized effector lymphocytes, particularly effector-memory CD8+ T-cells and NK-cells, displayed differentially expressed genes and enriched gene sets associated with anti-tumor activity, including cytotoxicity, migration/chemotaxis, antigen binding, cytokine responsiveness and alloreactivity (e.g. graft-versus-host/leukemia). Mice receiving exercise-mobilized PBMCs had lower tumor burden and higher overall survival (4.14E+08 photons/s and 47%, respectively) at day 40 compared to mice receiving resting PBMCs (12.1E+08 photons/s and 22%, respectively) from the same donors (p<0.05). Human immune cell engraftment was similar for resting and exercise-mobilized DLI. However, when compared to non-tumor bearing mice, K562 increased the expansion of NK-cell and CD3+/CD4-/CD8- T-cells in mice receiving exercise-mobilized but not resting lymphocytes, 1-2 weeks after DLI. No differences in GvHD or GvHD-free survival was observed between groups either with or without K562 challenge. Conclusion: Exercise in humans mobilizes effector lymphocytes with an anti-tumor transcriptomic profile and their use as DLI extends survival and enhances the graft-versus-leukemia (GvL) effect without exacerbating GvHD in human leukemia bearing xenogeneic mice. Exercise may serve as an effective and economical adjuvant to increase the GvL effects of allogeneic cell therapies without intensifying GvHD.

Exercise mobilizes diverse antigen specific T-cells and elevates neutralizing antibodies in humans with natural immunity to SARS CoV-2.

Epidemiological data suggest that physical activity protects against severe COVID-19 and improves clinical outcomes, but how exercise augments the SARS-CoV-2 viral immune response has yet to be elucidated. Here we determine the antigen-specific CD4 and CD8 T-cell and humoral immunity to exercise in non-vaccinated individuals with natural immunity to SARS CoV-2, using whole-blood SARS-CoV-2 peptide stimulation assays, IFN-γ ELISPOT assays, 8-color flow cytometry, deep T-cell receptor (TCR) ß sequencing, and anti-RBD-1 neutralizing antibody serology. We found that acute exercise reliably mobilized (∼2.5-fold increase) highly functional SARS-CoV-2-specific T-cells to the blood compartment in those with natural immunity to the virus. The mobilized cells reacted with spike protein (including alpha (α) and delta (δ)-variants), membrane, and nucleocapsid peptides in those previously infected but not in controls. Both groups reliably mobilized T-cells reacting with Epstein-Barr viral peptides. Exercise mobilized SARS-CoV-2 specific T-cells maintained broad TCR-ß diversity with no impact on CDR3 length or V and J family gene usage. Exercise predominantly mobilized MHC I restricted (i.e. CD8+) SARS-CoV-2 specific T-cells that recognized ORF1ab, surface, ORF7b, nucleocapsid, and membrane proteins. SARS-CoV-2 neutralizing antibodies were transiently elevated ∼1.5-fold during exercise after infection. In conclusion, we provide novel data on a potential mechanism by which exercise could increase SARS-CoV-2 immunosurveillance via the mobilization and redistribution of antigen-specific CD8 T-cells and neutralizing antibodies. Further research is needed to define the tissue specific disease protective effects of exercise as SARS-CoV-2 continues to evolve, as well as the impact of COVID-19 vaccination on this response.

Clonal Kinetics and Single-Cell Transcriptional Profiles of T Cells Mobilized to Blood by Acute Exercise.

PURPOSE: Acute exercise redistributes large numbers of memory T cells, which may contribute to enhanced immune surveillance in regular exercisers. It is not known, however, if acute exercise promotes a broad or oligoclonal T-cell receptor (TCR) repertoire or evokes transcriptomic changes in "exercise-responsive" T-cell clones. METHODS: Healthy volunteers completed a graded bout of cycling exercise up to 80% V̇O 2max . DNA was extracted from peripheral blood mononuclear cells collected at rest, during exercise (EX), and 1 h after (+1H) exercise, and processed for deep TCR-ß chain sequencing and tandem single-cell RNA sequencing. RESULTS: The number of unique clones and unique rearrangements was decreased at EX compared with rest ( P < 0.01) and +1H ( P < 0.01). Productive clonality was increased compared with rest ( P < 0.05) and +1H ( P < 0.05), whereas Shannon's Index was decreased compared with rest ( P < 0.05) and +1H ( P < 0.05). The top 10 rearrangements in the repertoire were increased at EX compared with rest ( P < 0.05) and +1H ( P < 0.05). Cross-referencing TCR-ß sequences with a public database (VDJdb) revealed that exercise increased the number of clones specific for the most prevalent motifs, including Epstein-Barr virus, cytomegalovirus, and influenza A. We identified 633 unique exercise-responsive T-cell clones that were mobilized and/or egressed in response to exercise. Among these clones, there was an upregulation in genes related to cell death, cytotoxicity, and activation ( P < 0.05). CONCLUSIONS: Acute exercise promotes an oligoclonal T-cell repertoire by preferentially mobilizing the most dominant clones, several of which are specific to known viral antigens and display differentially expressed genes indicative of cytotoxicity, activation, and apoptosis.

Acute exercise mobilizes NKT-like cells with a cytotoxic transcriptomic profile but does not augment the potency of cytokine-induced killer (CIK) cells.

CD3+/CD56+ Natural killer (NK) cell-like T-cells (NKT-like cells) represent <5% of blood lymphocytes, display a cytotoxic phenotype, and can kill various cancers. NKT-like cells can be expanded ex vivo into cytokine-induced killer (CIK) cells, however this therapeutic cell product has had mixed results against hematological malignancies in clinical trials. The aim of this study was to determine if NKT-like cells mobilized during acute cycling exercise could be used to generate more potent anti-tumor CIK cells from healthy donors. An acute exercise bout increased NKT-like cell numbers in blood 2-fold. Single cell RNA sequencing revealed that exercise mobilized NKT-like cells have an upregulation of genes and transcriptomic programs associated with enhanced anti-tumor activity, including cytotoxicity, cytokine responsiveness, and migration. Exercise, however, did not augment the ex vivo expansion of CIK cells or alter their surface phenotypes after 21-days of culture. CIK cells expanded at rest, during exercise (at 60% and 80% VO2max) or after (1h post) were equally capable of killing leukemia, lymphoma, and multiple myeloma target cells with and without cytokine (IL-2) and antibody (OKT3) priming in vitro. We conclude that acute exercise in healthy donors mobilizes NKT-like cells with an upregulation of transcriptomic programs involved in anti-tumor activity, but does not augment the ex vivo expansion of CIK cells.

Recent COVID-19 vaccination has minimal effects on the physiological responses to graded exercise in physically active healthy people.

Athletes are advised to receive the COVID-19 vaccination to protect themselves from SARS-CoV-2 infection during major competitions. Despite this, many athletes are reluctant to get the COVID-19 vaccine due to concerns that symptoms of vaccinosis may impair athletic performance. This study aimed to determine the effects of COVID-19 vaccination on the physiological responses to graded exercise. Healthy physically active participants completed a 20-min bout of graded cycling exercise at intensities corresponding to 50%, 60%, 70%, and 80% of the predetermined V̇O2max before and ∼21 days after receiving the COVID-19 vaccine (2-dose Pfizer mRNA or 1-dose Johnson & Johnson). Vaccination had no effect on a large number of physiological responses to exercise measured in blood (e.g., lactate, epinephrine, and cortisol) and by respiratory gas exchange (e.g., oxygen uptake, CO2 production, ventilation, respiratory exchange ratio, predicted V̇O2max, and ventilatory threshold) (P > 0.05). We did, however, find significant elevations in heart rate (∼5 beats/min) and norepinephrine (P = 0.006 and 0.04, respectively) in response to vigorous (i.e., 70%-80% V̇O2max) intensity exercise after vaccination, particularly in those who received the two-shot Pfizer mRNA vaccine regimen. These findings held true when compared with demographically matched controls who completed identical bouts of exercise several weeks apart without receiving a vaccine; delta values for heart rate (P = 0.03) and norepinephrine (P = 0.01) were elevated in the second trial for those who received the Pfizer mRNA vaccine compared with the controls at the 70% and 80% V̇O2max stages, respectively. Recent COVID-19 vaccination has minimal effects on the physiological responses to graded exercise in physically active healthy people. The small elevations in cardiovascular and neuroendocrine responses to exercise after the Pfizer mRNA vaccine regimen could have implications for athletes at the elite level and warrants investigation.NEW & NOTEWORTHY Recent COVID-19 vaccination does not affect a large number of physiological responses to graded exercise, indicating that vaccination is unlikely to impair exercise capacity in normal healthy people. Heart rate and norepinephrine levels were elevated in response to exercise after the two-dose Pfizer mRNA vaccination compared to controls. Small elevations in cardiovascular and neuroendocrine responses to exercise after recent COVID-19 vaccination could have implications for exercise performance in elite athletes and warrants investigation.

Acute exercise increases immune responses to SARS CoV-2 in a previously infected man.

Evidence is emerging that exercise and physical activity provides protection against severe COVID-19 disease in patients infected with SARS-CoV-2, but it is not known how exercise affects immune responses to the virus. A healthy man completed a graded cycling ergometer test prior to and after SARS-CoV-2 infection, then again after receiving an adenovirus vector-based COVID-19 vaccine. Using whole blood SARS-CoV-2 peptide stimulation assays, IFN-γ ELISPOT assays, flow cytometry, ex vivo viral-specific T-cell expansion assays and deep T-cell receptor (TCR) ß sequencing, we found that exercise robustly mobilized highly functional SARS-CoV-2 specific T-cells to the blood compartment that recognized spike protein, membrane protein, nucleocapsid antigen and the B.1.1.7 α-variant, and consisted mostly of CD3+/CD8+ T-cells and double-negative (CD4-/CD8-) CD3+ T-cells. The magnitude of SARS-CoV-2 T-cell mobilization with exercise was intensity dependent and robust when compared to T-cells recognizing other viruses (e.g. CMV, EBV, influenza). Vaccination enhanced the number of exercise-mobilized SARS-CoV-2 T-cells recognizing spike protein and the α-variant only. Exercise-mobilized SARS-CoV-2 specific T-cells proliferated more vigorously to ex vivo peptide stimulation and maintained broad TCR-ß diversity against SARS-CoV-2 antigens both before and after ex vivo expansion. Neutralizing antibodies to SARS-CoV-2 were transiently elevated during exercise after both infection and vaccination. Finally, infection was associated with an increased metabolic demand to defined exercise workloads, which was restored to pre-infection levels after vaccination. This case study provides impetus for larger studies to determine if these immune responses to exercise can facilitate viral clearance, ameliorate symptoms of long COVID syndrome, and/or restore functional exercise capacity following SARS-CoV-2 infection.

Regulatory Dendritic Cells Induced by Bendamustine Are Associated With Enhanced Flt3 Expression and Alloreactive T-Cell Death.

The growth factor Flt3 ligand (Flt3L) is central to dendritic cell (DC) homeostasis and development, controlling survival and expansion by binding to Flt3 receptor tyrosine kinase on the surface of DCs. In the context of hematopoietic cell transplantation, Flt3L has been found to suppress graft-versus-host disease (GvHD), specifically via host DCs. We previously reported that the pre-transplant conditioning regimen consisting of bendamustine (BEN) and total body irradiation (TBI) results in significantly reduced GvHD compared to cyclophosphamide (CY)+TBI. Pre-transplant BEN+TBI conditioning was also associated with greater Flt3 expression among host DCs and an accumulation of pre-cDC1s. Here, we demonstrate that exposure to BEN increases Flt3 expression on both murine bone marrow-derived DCs (BMDCs) and human monocyte-derived DCs (moDCs). BEN favors development of murine plasmacytoid DCs, pre-cDC1s, and cDC2s. While humans do not have an identifiable equivalent to murine pre-cDC1s, exposure to BEN resulted in decreased plasmacytoid DCs and increased cDC2s. BEN exposure and heightened Flt3 signaling are associated with a distinct regulatory phenotype, with increased PD-L1 expression and decreased ICOS-L expression. BMDCs exposed to BEN exhibit diminished pro-inflammatory cytokine response to LPS and induce robust proliferation of alloreactive T-cells. These proliferative alloreactive T-cells expressed greater levels of PD-1 and underwent increased programmed cell death as the concentration of BEN exposure increased. Alloreactive CD4+ T-cell death may be attributable to pre-cDC1s and provides a potential mechanism by which BEN+TBI conditioning limits GvHD and yields T-cells tolerant to host antigen.

Low sleep efficiency does not impact upper or lower limb vascular function in young adults.

NEW FINDINGS: What is the central question of this study? We sought to investigate whether young adults reporting low sleep quality possessed lower vascular function and altered autonomic nervous system modulation when compared with young adults reporting high sleep quality. What is the main finding and its importance? The study revealed that in young adults reporting low sleep quality, neither vascular nor autonomic function was significantly different when compared with young adults reporting high sleep quality. These findings suggest that young adults are either not substantially impacted by or can adequately adapt to the negative consequences commonly associated with poor sleep. ABSTRACT: The aim of the study was to investigate whether young adults reporting low sleep quality also possessed lower vascular function, potentially stemming from altered autonomic nervous system modulation, when compared with young adults reporting high sleep quality. Thirty-one healthy young adults (age 24 ± 4 years) underwent a 7 night sleep assessment (Actigraph GT3X accelerometer). After the sleep assessment, subjects meeting specific criteria were separated into high (HSE; ≥85%; n = 11; eight men and three women) and low (LSE; <80%; n = 11; nine men and two women) sleep efficiency groups. Peripheral vascular function was assessed in the upper and lower limb, using the flow-mediated dilatation technique in the arm (brachial artery) and leg (superficial femoral artery). Heart rate variability was evaluated during 5 min of rest and used frequency parameters reflective of parasympathetic and/or sympathetic nervous system modulation (high- and low-frequency parameters). By experimental design, significant differences in sleep quality between groups were reported, with the LSE group exhibiting a longer time awake after sleep onset, higher number of awakenings and longer average time per awakening when compared with the HSE group. Despite these differences in sleep quality, no significant differences in upper and lower limb vascular function and heart rate variability measures were revealed when comparing the LSE and HSE groups. Additionally, in all subjects (n = 31), no correlations between sleep efficiency and vascular function/autonomic modulation were revealed. This study revealed that low sleep quality does not impact upper or lower limb vascular function or autonomic nervous system modulation in young adults.

Inflamm-Aging Is Associated with Lower Plasma PTX3 Concentrations and an Impaired Capacity of PBMCs to Express hTERT following LPS Stimulation.

Age-related elevations in proinflammatory cytokines, known as inflamm-aging, are associated with shorter immune cell telomere lengths. Purpose. This study examined the relationship of plasma PTX3 concentrations, a biomarker of appropriate immune function, with telomere length in 15 middle-aged (40-64 years) and 15 young adults (20-31 years). In addition, PBMCs were isolated from middle-aged and young adults to examine their capacity to express a key mechanistic component of telomere length maintenance, human telomerase reverse transcriptase (hTERT), following ex vivo cellular stimulation. Methods. Plasma PTX3 and inflammatory cytokines (i.e., IL-6, IL-10, TGF-ß, and TNF-α), PBMC telomere lengths, and PBMC hTERT gene expression and inflammatory protein secretion following exposure to LPS, PTX3, and PTX3+LPS were measured. Results. Aging was accompanied by the accumulation of centrally located visceral adipose tissue, without changes in body weight and BMI, and alterations in the systemic inflammatory milieu (decreased plasma PTX3 and TGF-ß; increased TNF-α (p ≤ 0.050)). In addition, shorter telomere lengths in middle-aged compared to young adults (p = 0.011) were negatively associated with age, body fat percentages, and plasma TNF-α (r = -0.404, p = 0.027; r = -0.427, p = 0.019; and r = -0.323, p = 0.041, respectively). Finally, the capacity of PBMCs to increase hTERT gene expression following ex vivo stimulation was impaired in middle-aged compared to young adults (p = 0.033) and negatively associated with telomere lengths (r = 0.353, p = 0.028). Conclusions. Proinflammation and the impaired hTERT gene expression capacity of PBMCs may contribute to age-related telomere attrition and disease.

A Prior High-Intensity Exercise Bout Attenuates the Vascular Dysfunction Resulting From a Prolonged Sedentary Bout.

BACKGROUND: This study sought to determine the impact of an acute prior bout of high-intensity interval aerobic exercise on attenuating the vascular dysfunction associated with a prolonged sedentary bout. METHODS: Ten young (24 ± 1 y) healthy males completed two 3-hour sessions of prolonged sitting with (SIT-EX) and without (SIT) a high-intensity interval aerobic exercise session performed immediately prior. Prior to and 3 hours into the sitting bout, leg vascular function was assessed with the passive leg movement technique, and blood samples were obtained from the lower limb to evaluate changes in oxidative stress (malondialdehyde and superoxide dismutase) and inflammation (interleukin-6). RESULTS: No presitting differences in leg vascular function (assessed via passive leg movement technique-induced hyperemia) were revealed between conditions. After 3 hours of prolonged sitting, leg vascular function was significantly reduced in the SIT condition, but unchanged in the SIT-EX. Lower limb blood samples revealed no alterations in oxidative stress, antioxidant capacity, or inflammation in either condition. CONCLUSIONS: This study revealed that lower limb vascular dysfunction was significantly attenuated by an acute presitting bout of high-intensity interval aerobic exercise. Further analysis of lower limb blood samples revealed no changes in circulating oxidative stress or inflammation in either condition.

Aerobic fitness alters the capacity of mononuclear cells to produce pentraxin 3 following maximal exercise.

PURPOSE: Pentraxin 3 (PTX3) is a vital regulator of innate immune function. Although plasma PTX3 concentrations are elevated with aerobic fitness, the cellular functions of PTX3 remain unknown in aerobically trained and untrained subjects. METHODS: Thirty individuals (aerobically trained = 15 and untrained = 15) participated in a maximal exercise protocol to examine ex vivo PTX3 production from isolated peripheral blood mononuclear cells (PBMCs) exposed to LPS or palmitate. The capacity of PTX3 to stimulate inflammatory cytokine production ex vivo was also examined. RESULTS: Elevated plasma PTX3 concentrations prior to exercise were positively associated with the percent change (pre to post exercise) in plasma PTX3 concentrations in all subjects, independent of cardiorespiratory fitness (VO2max). In addition, elevated plasma PTX3 concentrations in aerobically trained subjects at rest predicted changes in the LPS- and palmitate-stimulated PTX3 production from isolated PBMCs following acute exercise. In response to PTX3 simulation, the capacity of PBMCs to produce the anti-inflammatory cytokine IL-10 was decreased following acute exercise in all subject (no changes in IL-6, TGF-ß1, and TNF-α observed). However, the percent change in IL-6 production was positively associated with VO2max in all subjects, and in aerobically trained subjects only, positively associated with elevated plasma PTX3 concentrations at rest and in response to acute exercise. CONCLUSION: These results suggest that aerobic training enhances the utilization of plasma PTX3 concentrations to predict the capacity of mononuclear cells to produce PTX3, and potentially, its reciprocal role of PTX3 as an initiator of the innate immune response following maximal exercise.

Maximal Exercise Alters the Inflammatory Phenotype and Response of Mononuclear Cells.

PURPOSE: Monocytes express the CD14 receptor that facilitates lipopolysaccharide (LPS) ligation to toll-like receptor 4 (TLR4) to elicit production of interleukin (IL)-6, IL-10, and tumor necrosis factor alpha (TNF-α). However, proinflammatory conditions, such as strenuous exercise, increase the percentage of monocytes expressing CD16, a receptor that enhances LPS stimulated TNF-α production. Therefore, we examined whether maximal treadmill exercise would alter the inflammatory phenotype of classical (CD14/CD16) and proinflammatory monocytes (intermediate [CD14/CD16] and nonclassical [CD14/CD16]), evidenced by changes in TLR4, CD14, and CD16 receptor expression, and their inflammatory response to ex vivo LPS stimulation. METHODS: Human mononuclear cells from 25 male participants (age, 24.2 ± 4.0 yr) were isolated before and after exercise to assess TLR4, CD14, and CD16 expression by flow cytometry and ex vivo production of LPS-stimulated inflammatory cytokines (IL-6, IL-10, and TNF-α). RESULTS: Exercise reduced the percentage of classical monocytes and increased the percentage of intermediate and nonclassical monocytes. In addition, TLR4 expression decreased on classical and intermediate monocytes, but not the nonclassical monocyte subset. Furthermore, although CD14 expression decreased on all monocyte subsets, CD16 expression increased on intermediate monocytes only. In parallel with these phenotypic changes, the inflammatory milieu shifted toward a proinflammatory response after LPS stimulation (decreased IL-6 and IL-10 and increased IL-6 to IL-10 ratio and TNF-α production). CONCLUSIONS: These findings demonstrate that acute maximal exercise elicits a proinflammatory phenotype of isolated monocytes exposed to LPS and highlight potential mechanisms that will help elucidate the role of acute and chronic exercise on the innate immune response of circulating monocytes.