A systematic literature review on the effects of exercise on human Toll-like receptor expression.

BACKGROUND: Toll-like receptors (TLRs) are a family of transmembrane pattern recognition receptors that are mainly expressed on immune cells. Recognition of various exogenous and endogenous molecular patterns activates the TLR signalling cascade, which orchestrates an inflammatory immune response. Dysfunctional immune responses, including aberrant TLR signalling, are increasingly implicated in the associations between sedentarism, chronic low-grade systemic inflammation and various non-communicable diseases. Conversely, exercise exerts anti-inflammatory effects, which could be conferred through its immunomodulatory properties, potentially affecting TLRs. This study aims to systematically review the effects of exercise on human TLR expression. METHOD: A systematic literature search of Pubmed, Embase, The Cochrane Library and SPORTDiscus for articles addressing the impact of exercise (as isolated intervention) on TLRs in humans was conducted, ending in February 2020. RESULTS: A total of 66 articles were included. The publications were categorised according to exercise modality and duration: acute resistance exercise (4 studies), acute aerobic exercise (26 studies), resistance training program (9 studies), aerobic training program (16 studies), combined (i.e. resistance and aerobic) training program (8 studies) and chronic exercise not otherwise classifiable (9 studies). Five articles investigated more than one of the aforementioned exercise categories. Several trends could be discerned with regard to the TLR response in the different exercise categories. Acute resistance exercise seemed to elicit TLR upregulation, whereas acute aerobic exercise had less activating potential with the majority of responses being neutral or, especially in healthy participants, downregulatory. Chronic resistance and combined exercise programs predominantly resulted in unaltered or decreased TLR levels. In the chronic aerobic exercise category, mixed effects were observed, but the majority of measurements demonstrated unchanged TLR expression. CONCLUSION: Currently published research supports an interplay between exercise and TLR signalling, which seems to depend on the characteristics of the exercise. However, there was large heterogeneity in the study designs and methodologies. Therefore, additional research is required to further corroborate these findings, to define its pathophysiological implications and to elucidate the mechanism(s) linking exercise to TLR signalling.

Circulating MicroRNA as Biomarkers of Anthracycline-Induced Cardiotoxicity: JACC: CardioOncology State-of-the-Art Review.

Close monitoring for cardiotoxicity during anthracycline chemotherapy is crucial for early diagnosis and therapy guidance. Currently, monitoring relies on cardiac imaging and serial measurement of cardiac biomarkers like cardiac troponin and natriuretic peptides. However, these conventional biomarkers are nonspecific indicators of cardiac damage. Exploring new, more specific biomarkers with a clear link to the underlying pathomechanism of cardiotoxicity holds promise for increased specificity and sensitivity in detecting early anthracycline-induced cardiotoxicity. miRNAs (microRNAs), small single-stranded, noncoding RNA sequences involved in epigenetic regulation, influence various physiological and pathological processes by targeting expression and translation. Emerging as new biomarker candidates, circulating miRNAs exhibit resistance to degradation and offer a direct pathomechanistic link. This review comprehensively outlines their potential as early biomarkers for cardiotoxicity and their pathomechanistic link.

Exercise training in women with cardiovascular disease: Differential response and barriers - review and perspective.

BACKGROUND: Exercise-based cardiac rehabilitation has a class 1A recommendation in coronary artery disease and heart failure based on its beneficial effects on mortality, morbidity and quality of life. However, the inter-individual response to exercise training is highly variable and influenced by both training and patient characteristics. Notably, men and women display a different training response, even when accounting for age, height and lean muscle mass. Most studies investigating exercise effects on various physiological outcomes focus on male patients. Because women are understudied, the scientific evidence for tailored exercise prescription in women is still limited. METHODS: This narrative review summarises: (a) the underlying physiological determinants of the response to exercise training in women with cardiovascular disease, in which women rely more on fat than on carbohydrate oxidation during exercise, have lower aerobic capacities and smaller increases in cardiac function during exercise; (b) the benefits and barriers of exercise in women, in whom improving cardiometabolic risk and quality of life is weighed against socioeconomic and psychological needs; and (c) the relevance of different clinical endpoints in exercise trials such as maximum oxygen uptake, morbidity, mortality, training characteristics, quality of life and metabolic or vascular endpoints. RESULTS: Finally, we provide a perspective on how to improve referral, enrolment and adherence to exercise training in women, with structured approaches to inform the referring physician as well as the patient, and offering more flexible, gender-tailored or tele/smartphone-based programmes while addressing the socioeconomic and psychological needs of the patients. This may ultimately improve the admission, adherence and outcome of exercise-based cardiac rehabilitation in women.

MicroRNAs targeting VEGF are related to vascular dysfunction in preeclampsia.

In preeclampsia (PE), pre-existent maternal endothelial dysfunction leads to impaired placentation and vascular maladaptation. The vascular endothelial growth factor (VEGF) pathway is essential in the placentation process and VEGF expression is regulated through post-transcriptional modification by microRNAs (miRNAs). We investigated the expression of VEGF-related circulating miR-16, miR-29b, miR-126, miR-155 and miR-200c in PE vs healthy pregnancies (HPs), and their relation with vascular function, oxidative stress (OS) and systemic inflammation. In this case-control study, 24 women with early PE (<34 weeks) were compared with 30 women with HP. Circulating microRNA levels (RT-qPCR), OS and systemic inflammation were assessed in plasma samples (PE 29.5 vs HP 25.8 weeks) and related to extensive in vivo vascular function (flow-mediated dilatation (FMD), modified FMD (mFMD), carotid-femoral pulse wave velocity (CF-PWV), heart rate corrected augmentation index (AIx75) and reactive hyperemia index (RHI)). FMD, CF-PWV, AIx75 and RHI were all significantly impaired in PE (P<0.05). PE patients had reduced levels of miR-16 (5.53 ± 0.36 vs 5.84 ± 0.61) and increased levels of miR-200c (1.34 ± 0.57 vs 0.97 ± 0.68) (P<0.05). Independent of age and parity, miR-16 was related to impaired FMD (ß 2.771, 95% C.I.: 0.023-5.519, P=0.048) and mFMD (ß 3.401, 95% C.I.: 0.201-6.602, P=0.038). Likewise, miR-200c was independently associated with CF-PWV (ß 0.513, 95% C.I.: 0.034-0.992, P=0.036). In conclusion, circulating levels of miR-16 were lower in PE, which correlated with impaired endothelial function. Circulating miR-200c was increased in PE and correlated with higher arterial stiffness. These findings suggest a post-transcriptional dysregulation of the VEGF pathway in PE and identify miR-16 and miR-200c as possible diagnostic biomarkers for PE.

Circulating microRNA as predictors for exercise response in heart failure with reduced ejection fraction.

AIMS: Exercise training is a powerful adjunctive therapy in patients with heart failure with reduced ejection fraction (HFrEF), but ca. 55% of patients fail to improve VO2peak. We hypothesize that circulating microRNAs (miRNAs), as epigenetic determinants of VO2peak, can distinguish exercise responders (ER) from exercise non-responders (ENR). METHODS AND RESULTS: We analysed 377 miRNAs in 18 male HFrEF patients (9 ER and 9 ENR) prior to 15 weeks of exercise training using a miRNA array. ER and ENR were defined as change in VO2peak of >20% or <6%, respectively. First, unsupervised clustering analysis of the miRNA pattern was performed. Second, differential expression of miRNA in ER and ENR was analysed and related to percent change in VO2peak. Third, a gene set enrichment analysis was conducted to detect targeted genes and pathways. Baseline characteristics and training volume were similar between ER and ENR. Unsupervised clustering analysis of miRNAs distinguished ER from ENR with 83% accuracy. A total of 57 miRNAs were differentially expressed in ENR vs. ER. A panel of seven miRNAs up-regulated in ENR (Let-7b, miR-23a, miR-140, miR-146a, miR-191, miR-210, and miR-339-5p) correlated with %changeVO2peak (all P < 0.05) and predicted ENR with area under the receiver operating characteristic curves ≥0.77. Multiple pathways involved in exercise adaptation processes were identified. CONCLUSION: A fingerprint of seven miRNAs involved in exercise adaptation processes is highly correlated with VO2peak trainability in HFrEF, which holds promise for the prediction of training response and patient-targeted exercise prescription.

Plasma-Derived microRNAs Are Influenced by Acute and Chronic Exercise in Patients With Heart Failure With Reduced Ejection Fraction.

Background: Exercise training improves VO2peak in heart failure with reduced ejection fraction (HFrEF), but the effect is highly variable as it is dependent on peripheral adaptations. We evaluated changes in plasma-derived miRNAs by acute and chronic exercise to investigate whether these can mechanistically be involved in the variability of exercise-induced adaptations. Methods: Twenty-five male HFrEF patients (left ventricular ejection fraction < 40%, New York Heart Association class ≥ II) participated in a 15-week combined strength and aerobic training program. The effect of training on plasma miRNA levels was compared to 21 male age-matched sedentary HFrEF controls. Additionally, the effect of a single acute exercise bout on plasma miRNA levels was assessed. Levels of 5 miRNAs involved in pathways relevant for exercise adaptation (miR-23a, miR-140, miR-146a, miR-191, and miR-210) were quantified using RT-qPCR and correlated with cardiopulmonary exercise test (CPET), echocardiographic, vascular function, and muscle strength variables. Results: Expression levels of miR-146a decreased with training compared to controls. Acute exercise resulted in a decrease in miR-191 before, but not after training. Baseline miR-23a predicted change in VO2peak independent of age and left ventricular ejection fraction (LVEF). Baseline miR-140 was independently correlated with change in load at the respiratory compensation point and change in body mass index, and baseline miR-146a with change in left ventricular mass index. Conclusion: Plasma-derived miRNAs may reflect the underlying mechanisms of exercise-induced adaptation. In HFrEF patients, baseline miR-23a predicted VO2peak response to training. Several miRNAs were influenced by acute or repeated exercise. These findings warrant exploration in larger patient populations and further mechanistic in vitro studies on their molecular involvement.

miR-181c level predicts response to exercise training in patients with heart failure and preserved ejection fraction: an analysis of the OptimEx-Clin trial.

AIMS: In patients with heart failure with preserved ejection fraction (HFpEF), exercise training improves the quality of life and aerobic capacity (peakV·O2). Up to 55% of HF patients, however, show no increase in peakV·O2 despite adequate training. We hypothesized that circulating microRNAs (miRNAs) can distinguish exercise low responders (LR) from exercise high responders (HR) among HFpEF patients. METHODS AND RESULTS: We selected HFpEF patients from the Optimizing Exercise Training in Prevention and Treatment of Diastolic HF (OptimEx) study which attended ≥70% of training sessions during 3 months (n = 51). Patients were defined as HR with a change in peakV·O2 above median (6.4%), and LR as below median (n = 30 and n = 21, respectively). Clinical, ergospirometric, and echocardiographic characteristics were similar between LR and HR. We performed an miRNA array (n = 377 miRNAs) in 14 age- and sex-matched patients. A total of 10 miRNAs were upregulated in LR, of which 4 correlated with peakV·O2. Validation in the remaining 37 patients indicated that high miR-181c predicted reduced peakV·O2 response (multiple linear regression, ß = -2.60, P = 0.011), and LR status (multiple logistic regression, odds ratio = 0.48, P = 0.010), independent of age, sex, body mass index, and resting heart rate. Furthermore, miR-181c decreased in LR after exercise training (P-group = 0.030, P-time = 0.048, P-interaction = 0.037). An in silico pathway analysis identified several downstream targets involved in exercise adaptation. CONCLUSIONS: Circulating miR-181c is a marker of the response to exercise training in HFpEF patients. High miR-181c levels can aid in identifying LR prior to training, providing the possibility for individualized management.

The Effect of Exercise Training During Pregnancy to Improve Maternal Vascular Health: Focus on Gestational Hypertensive Disorders.

Hypertensive disorders of pregnancy, including gestational hypertension and pre-eclampsia, occur in up to 10% of pregnancies and are associated with increased life-long cardiovascular risk. Physical activity improves cardiovascular health in pregnancy and may lower the risk of developing hypertensive disorders of pregnancy. However, a minority of pregnant women comply with the recommended level of physical activity. Adequate knowledge on the physiological effects of exercise in healthy pregnancy could help to overcome potential barriers as pregnancy is a unique window of opportunity to improve health outcomes for both mother and child. In this mini review, we discuss structural and functional vascular adaptations during healthy and hypertensive pregnancies, we elaborate on the effects of exercise on the vasculature and review the safety and existing evidence of exercise training as preventive therapy for gestational hypertensive disorders.

Predictors of response to exercise training in patients with coronary artery disease - a subanalysis of the SAINTEX-CAD study.

Exercise training improves peak oxygen uptake, an important predictor of mortality in coronary artery disease patients. The influence of clinical and disease characteristics on training response is not well established in coronary artery disease. Therefore, we aimed to evaluate whether baseline cardiovascular disease variables and training intensity can predict the maximal aerobic response to exercise training. The Study on Aerobic INTerval EXercise training in coronary artery disease patients (SAINTEX-CAD) previously showed that 12 weeks of aerobic interval training and continuous training equally improved peak oxygen uptake in coronary artery disease patients. We identified 24 exercise non-responders (change peak oxygen uptake <1 ml/kg/min) among 167 participants in SAINTEX-CAD. In a between-group comparison, exercise non-responders were older, their baseline peak oxygen uptake and oxygen uptake efficiency slope were higher, and exercise non-responders were more frequently included after elective percutaneous coronary intervention (all p < 0.05). In multiple logistic regression analysis, age (odds ratio = 1.11 (1.04-1.18), p = 0.001), history of elective percutaneous coronary intervention (odds ratio = 3.31 (1.12-9.76), p = 0.030) and higher baseline peak oxygen uptake (odds ratio = 1.16 (1.06-1.27), p = 0.001) were independent predictors of exercise non-response. In multiple linear regression analysis, age (ß = -0.605, p = 0.001), history of elective percutaneous coronary intervention (ß = -15.401, p = 0.010), training intensity (ß=0.447, p = 0.008), baseline physical activity (ß=0.014, p = 0.003) and oxygen uptake efficiency slope (ß = -0.014, p < 0.001) predicted percentage change in peak oxygen uptake and explained 41% of the variability in percentage change in peak oxygen uptake. To summarize, 14% of coronary artery disease patients were exercise non-responders. Higher baseline peak oxygen uptake and oxygen uptake efficiency slope, history of elective percutaneous coronary intervention, older age, lower training intensity and lower baseline physical activity were predictors of training non-response. Identification of patients with a large likelihood of non-response is a first step towards patient tailored exercise programmes.

MicroRNA Isolation from Plasma for Real-Time qPCR Array.

MicroRNAs are short non-coding RNAs that regulate gene expression at the post-transcriptional level by mRNA degradation or suppression of translation. Their stability in plasma makes them attractive biomarkers. Since many plasma microRNA isolation procedures exist and the yield can be highly variable, we recently optimized the microRNA isolation and preamplification procedure using the mirVana PARIS kit (Thermo Fisher Scientific) for miRNA quantification with TaqMan Low Density Arrays in plasma samples. The method here is slightly modified from the original procedure supplied by Thermo Fisher. Based on our findings, recommendations are the following: (1) use Arabidopsis thaliana (Ath) miR-159a as spike-in control, (2) use a 100-µl elution volume during RNA isolation, and (3) add a preamplification step without dilution of the preamplification product. In this article we provide a step-by-step microRNA isolation and quantification procedure using human plasma samples for TaqMan Low Density Arrays. © 2018 by John Wiley & Sons, Inc.

MicroRNA profiling in plasma samples using qPCR arrays: Recommendations for correct analysis and interpretation.

MicroRNA (miRNA) regulate gene expression through posttranscriptional mRNA degradation or suppression of translation. Many (pre)analytical issues remain to be resolved for miRNA screening with TaqMan Low Density Arrays (TLDA) in plasma samples, such as optimal RNA isolation, preamplification and data normalization. We optimized the TLDA protocol using three RNA isolation protocols and preamplification dilutions. By using 100µL elution volume during RNA isolation and adding a preamplification step without dilution, 49% of wells were amplified. Informative target miRNA were defined as having quantification cycle values ≤35 in at least 20% of samples and low technical variability (CV across 2 duplicates of 1 sample <4%). A total of 218 miRNA was considered informative (= 59% of all target miRNA). Different normalization strategies were compared: exogenous Ath-miR-159a, endogenous RNA U6, and three mathematical normalization techniques: geNorm (Qbase, QB) and NormFinder (NF) normalization algorithms, and global mean calculation. To select the best normalization method, technical variability, biological variability, stability, and the extent to which the normalization method reduces data dispersion were calculated. The geNorm normalization algorithm reduced data dispersion to the greatest extent, while endogenous RNA U6 performed worst. In conclusion, for miRNA profiling in plasma samples using TLDA cards we recommend: 1. Implementing a preamplification step in the TLDA protocol without diluting the final preamplification product 2. A stepwise approach to exclude non-informative miRNA based on quality control parameters 3. Against using snoRNA U6 as normalization method for relative quantification 4. Using the geNorm algorithm as normalization method for relative quantification.