Physical training, inflammation and bone integrity in elite female rowers

This study examined whether fluctuations in training load during an Olympic year lead to changes in mineral properties and factors that regulate bone (sclerostin (SOST), osteoprotegerin (OPG)), and receptor activator of nuclear factor kappa-B ligand (RANKL)) and energy metabolism (insulin-like growth factor-1 (IGF-1) and leptin), and inflammation (tumor necrosis factor-α (TNF-α)) in elite heavyweight female rowers. Blood samples were drawn from female heavy-weight rowers (n=15) (27.0±0.8y, 80.9±1.3 kg, 179.4±1.4 cm) at baseline (T1 – 45 weeks pre-Olympic Games) and following 7, 9, 20, 25 and 42 weeks (T1-6, respectively). Serum was analyzed by Multiplex assays (EMD Millipore, Toronto, CAN). Total weekly training load was recorded over the weeks prior to each time point. Bone mineral density (BMD) was measured by dual energy X-ray absorptiometry at T1 and T6. Total BMD increased significantly pre- to post-training (+1.6%). OPG, IGF-1, and leptin were not different across all time points. OPG/RANKL was significantly higher at both T4 and 5 compared to T1 and 2. High training load (T5) was associated with the highest TNF-α levels (2.1 pg/ml), and a parallel increase in SOST (993.1 pg/ml), while low training load (T6 - recovery) was associated with significantly lower TNF-α (1.5 pg/ml) and a parallel decrease in SOST (741.0 pg/ml). Leptin was a significant determinant of bone-mineral properties in these athletes. These results suggest exercise training can lead to an increase in OPG/RANKL, and training load periodization can control the inflammatory response associated with intense training, and combined with adequate caloric intake can preserve bone mineral integrity in elite female athletes

Characterization of sclerostin’s response within white adipose tissue to an obesogenic diet at rest and in response to acute exercise in male mice

This study examined the effect of a high-fat diet (HFD) on sclerostin content within subcutaneous inguinal visceral white adipose tissue (iWAT), and visceral epididymal WAT (eWAT) depots at rest and in response to acute aerobic exercise. Male C57BL/6 mice (n=40, 18 weeks of age) underwent 10 weeks of either a low-fat diet (LFD) or HFD. Within each diet group, mice were assigned to either remain sedentary (SED) or perform 2h of endurance treadmill exercise at 15 m·min-1 with 5° incline (EX), creating 4 groups: LFD+SED (N=10), LFD+EX (N=10), HFD+SED (N=10), and HFD+EX (N=10). Serum and WAT depots were collected 2h post-exercise. Serum sclerostin showed a diet-by-exercise interaction, reflecting HFD+EX mice having higher concentration than HFD-SED (+31%, p=0.03), and LFD mice being unresponsive to exercise. iWAT sclerostin content decreased post-exercise in both 28 kDa (-31%, p=0.04) and 30 kDa bands (-36%, main effect for exercise, p=0.02). iWAT b-catenin (+44%, p=0.03) and GSK3b content were elevated in HFD mice compared to LFD (+128%, main effect for diet, p=0.005). Monomeric sclerostin content was abolished in eWAT of HFD mice (-96%, main effect for diet, p<0.0001), was only detectable as a 30 kDa band in LFD mice and was unresponsive to exercise. b-catenin and GSK3b were both unresponsive to diet and exercise within eWAT. These results characterized sclerostin’s mobilization to WAT depots in response to acute exercise, which appears to be specific to a reduction in iWAT and identified a differential regulation of sclerostin’s form/post-translational modifications depending on diet and WAT depot.This research was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC grant to P. Klentrou # 2020-00014). N. Kurgan, B. Baranowski and Joshua Stoikos hold NSERC doctoral scholarships

A Low-Therapeutic Dose of Lithium Inhibits GSK3 and Enhances Myoblast Fusion in C2C12 Cells

Glycogen synthase kinase 3 (GSK3) slows myogenic differentiation and myoblast fusion partly by inhibiting the Wnt/β-catenin signaling pathway. Lithium, a common medication for bipolar disorder, inhibits GSK3 via Mg+ competition and increased Ser21 (GSK3α) or Ser9 (GSK3β) phosphorylation, leading to enhanced myoblast fusion and myogenic differentiation. However, previous studies demonstrating the effect of lithium on GSK3 have used concentrations up to 10 mM, which greatly exceeds concentrations measured in the serum of patients being treated for bipolar disorder (0.5–1.2 mM). Here, we determined whether a low-therapeutic (0.5 mM) dose of lithium could promote myoblast fusion and myogenic differentiation in C2C12 cells. C2C12 myotubes differentiated for three days in media containing 0.5 mM lithium chloride (LiCl) had significantly higher GSK3β (ser9) and GSK3α (ser21) phosphorylation compared with control myotubes differentiated in the same media without LiCl (+2–2.5 fold, p < 0.05), a result associated with an increase in total β-catenin. To further demonstrate that 0.5 mM LiCl inhibited GSK3 activity, we also developed a novel GSK3-specific activity assay. Using this enzyme-linked spectrophotometric assay, we showed that 0.5 mM LiCl-treated myotubes had significantly reduced GSK3 activity (−86%, p < 0.001). Correspondingly, 0.5 mM LiCl treated myotubes had a higher myoblast fusion index compared with control (p < 0.001) and significantly higher levels of markers of myogenesis (myogenin, +3-fold, p < 0.001) and myogenic differentiation (myosin heavy chain, +10-fold, p < 0.001). These results indicate that a low-therapeutic dose of LiCl is sufficient to promote myoblast fusion and myogenic differentiation in muscle cells, which has implications for the treatment of several myopathic conditionsBrock University Library Open Access Publishing Fun

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Sclerostin influences body composition adaptations to exercise training

Sclerostin is a secreted glycoprotein mainly produced by the osteocyte, which inhibits the canonical Wnt/ß-catenin signalling pathway. In mice, genetic deletion, or inhibition of sclerostin with a neutralizing antibody increases bone mass while also improving insulin sensitivity and lipid homeostasis. Despite sclerostin not being expressed by adipose tissue (AT), reductions in white AT (WAT) mass and adipocyte cross-sectional area can also be observed with sclerostin inhibition, ultimately conferring resistance to a high-fat diet. Resting circulating sclerostin has also been shown to decrease following exercise training. This dissertation includes six studies examining the hypothesis that sclerostin influences adaptations in fat mass in response to exercise training. Study 1 did not identify serum sclerostin’s response to acute exercise with a top-down proteomic analysis. Study 2 of this thesis utilized a targeted approach and found sclerostin increases in the circulation transiently following acute exercise in adolescents with excess adiposity while those with normal weight have a blunted response. Study 3 utilized a longitudinal study design and found a diet and exercise intervention that leads to a reduction in fat mass attenuates sclerostin’s post-exercise increase in adolescents with excess adiposity. Study 4 identified sclerostin was present in human AT and decreased following exercise training in adults with excess adiposity. Study 5 characterized sclerostin’s response to acute exercise within serum and WAT depots of a mouse model and showed that serum sclerostin is elevated during recovery only in obese mice compared to lean mice and the monomeric form of sclerostin is reduced in scWAT during recovery from acute exercise and is abolished in visceral WAT in response to an obesogenic diet. Study 6 showed that prevention in the reduction in sclerostin seen with exercise with daily injections of recombinant sclerostin also prevents the reduction in scWAT mass and adipocyte cell size and increased lean mass seen with exercise training. These changes may be related to a shift in fuel utilization. Taken together, this thesis provides evidence that sclerostin is influenced by adiposity and exercise training and fluctuations in sclerostin content can regulate adaptations in fat mass and lean mass, which may be mediated by changes in metabolism

Inhibition of Human Lung Cancer Cell Proliferation and Survival by Post-Exercise Serum Is Associated with the Inhibition of Akt, mTOR, p70 S6K, and Erk1/2

Non-small cell lung cancer (NSCLC) accounts for 85% of all lung cancer cases, and for the most cancer-related deaths. The survival pathway of Akt, its downstream effectors, the mammalian target of rapamycin (mTOR) and ribosomal protein S6 kinase (p70 S6K), and the Ras-extracellular signal-regulated kinase (Erk1/2) pathways are activated in cancer leading to cell survival and growth. Thus, approaches that inhibit these signaling molecules may prove useful in the fight against lung cancer. Exercise is associated with health benefits and a limited number of studies indicate that serum from physically active individuals inhibit mammary and prostate cancer cell growth. In this study, we examined the effects of post exercise serum on proliferation, survival, and signaling cascades of human NSCLC cells. Blood was collected from male subjects prior to, 5 min, 1 h, and 24 h after a single bout of high intensity interval exercise on a cycle ergometer. Exposure of NSCLC cells to post exercise serum resulted in the inhibition of cell proliferation and survival, as well as significant reduction of phosphorylated/activated Akt, mTOR, p70 S6K, and Erk1/2 levels compared to cells treated with serum taken pre-exercise. Our data suggest that post exercise serum has anti-cancer properties in lung cancer and deserves further systematic investigation in animal models

Correction: Klentrou et al. Circulating Levels of Bone Markers after Short-Term Intense Training with Increased Dairy Consumption in Adolescent Female Athletes. <i>Children</i> 2021, <i>8</i>, 961

There was an error in the original publication [...

Circulating Levels of Bone Markers after Short-Term Intense Training with Increased Dairy Consumption in Adolescent Female Athletes

Thirteen female adolescent soccer players (14.3 ± 1.3 years) participated in a cross-over, double-blind trial examining the effects of Greek yogurt (GY) consumption on bone biomarkers during 5 days of intense soccer training. The study took place over two intervention weeks, which consisted of a pre-training assessment day, 5 training days, and a post-training assessment day. Participants completed the GY condition and a carbohydrate isocaloric placebo control pudding condition (CHO) in random order, 4 weeks apart. Morning, fasted, resting blood samples were collected pre- and post-training in each condition. Total osteocalcin (tOC), undercarboxylated osteocalcin (unOC), C-terminal telopeptide of type 1 collagen (CTX), osteoprotegerin (OPG), and receptor activator nuclear factor kappa-β ligand (RANKL) were measured in serum. The results showed no effects for time (pre- to post-training) or condition, and no interaction for tOC, CTX, OPG, RANKL, and the OPG/RANKL ratio. A time-by-condition interaction (p = 0.011) was observed in unOC, reflecting a post-training decrease in the GY, but not the CHO condition (−26% vs. −3%, respectively). However, relative unOC (% of tOC) decreased post-training (−16%), with no differences between conditions. These findings suggest that short-term high-impact intense training had no direct catabolic impact on bone metabolism, with GY adding no benefit beyond that of the isocaloric CHO control pudding

Changes to the human serum proteome in response to high intensity interval exercise : a sequential top-down proteomic analysis

Exercise has been shown to improve health status and prevent chronic diseases. In contrast, overtraining can lead to maladaptation and detrimental health outcomes. These outcomes appear to be mediated in part by released peptides and, potentially, alterations in protein abundances and their modified forms, termed proteoforms. Proteoform biomarkers that either predict the beneficial effects of exercise or indicate (mal)adaptation are yet to be elucidated. Thus, we assessed the influence of high-intensity interval exercise (HIIE) on the human serum proteome to identify novel exercise-regulated proteoforms. To this end, a top-down proteomics approach was used, whereby two-dimensional gel electrophoresis was used to resolve and differentially profile intact proteoforms, followed by protein identification via liquid chromatography-tandem mass spectrometry. Blood was collected from six young-adult healthy males, pre-exercise and 5 min and 1 h post-exercise. Exercise consisted of a maximal cycle ergometer test followed by 8 min x 1 min high-intensity intervals at 90% Wmax, with 1 min non-active recovery between intervals. Twenty resolved serum proteoforms changed significantly in abundance at 5 min and/or 1 h post-HIIE, including apolipoproteins, serpins (protease inhibitors), and immune system proteins, known to have broad anti-inflammatory and antioxidant effects, involvement in lipid clearance, and cardio-/neuro-protective effects. This initial screening for potential biomarkers indicates that a top-down analytical proteomic approach may prove useful in further characterizing the response to exercise and in understanding the molecular mechanisms that lead to health benefits, as well as identifying novel biomarkers for exercise (mal)adaptation

Cytokine concentrations in saliva vs. plasma at rest and in response to intense exercise in adolescent athletes

Background Salivary measures are advantageous in conducting large paediatric studies involving repeated measures. However, research measuring salivary cytokines in youth is limited. Aim Compare salivary with plasma concentrations of inflammatory cytokines at rest and following exercise in adolescent swimmers (21 male, 22 female). Methods Following collection of resting saliva and blood samples, participants performed a bout of high-intensity interval swimming, with samples taken again ∼15 min post-swimming and analysed for interleukin-6 (IL-6), interleukin 10 (IL-10), and tumour necrosis factor-alpha (TNF-α). Results Resting IL-10 was significantly lower, while IL-6 and TNF-α were significantly higher in saliva compared with plasma. IL-10 increased from pre- to post-swimming in plasma, but less so in saliva (51% vs. 29%; p = 0.02). TNF-α decreased post-swimming in saliva, but not in plasma (–27% vs −1%; p = 0.01). IL-6 decreased post-swimming in saliva compared with plasma (–21% vs. −3%; p = 0.06). Intraclass correlation coefficients (ICC) revealed no association between salivary and plasma IL-6 and TNF-α, while IL-10 showed a weak correlation only at rest (ICC = 0.39; p = 0.05). Conclusions Differences in concentrations and exercise responses, along with weak correlations, suggest that salivary cytokine levels are not an accurate representation of blood cytokine levels, and should not be used as a surrogate measure in paediatric studies