Changes in thioredoxin concentrations: an observation in an ultra-marathon race

Impact of Plasma Oxidative Stress Markers on Post-race Recovery in Ultramarathon Runners: A Sex and Age Perspective Overview

Oxidative stress has been widely studied in association to ultra-endurance sports. Although it is clearly demonstrated the increase in reactive oxygen species and free radicals after these extreme endurance exercises, the effects on the antioxidant defenses and the oxidative damage to macromolecules, remain to be fully clarified. Therefore, the aim of this study was to elucidate the impact of an ultramarathon race on the plasma markers of oxidative stress of 32 runners and their post-race recovery, with especial focused on sex and age effect. For this purpose, the antioxidant enzymes glutathione peroxidase (GPx) and glutathione reductase (GR) activity, as well as the lipid peroxidation product malondialdehyde (MDA) and the carbonyl groups (CG) content were measured before the race, in the finish line and 24 and 48 h after the race. We have reported an increase of the oxidative damage to lipids and proteins (MDA and CG) after the race and 48 h later. Moreover, there was an increase of the GR activity after the race. No changes were observed in runners' plasma GPx activity throughout the study. Finally, we have observed sex and age differences regarding damage to macromolecules, but no differences were found regarding the antioxidant enzymes measured. Our results suggest that several basal plasma markers of oxidative stress might be related to the extent of muscle damage after an ultraendurance race and also might affect the muscle strength evolution.

Characterization of extracellular redox enzyme concentrations in response to exercise in humans

Redox enzymes modulate intracellular redox balance and are secreted in response to cellular oxidative stress, potentially modulating systemic inflammation. Both aerobic and resistance exercise are known to cause acute systemic oxidative stress and inflammation; however, how redox enzyme concentrations alter in extracellular fluids following bouts of either type of exercise is unknown. Recreationally active men (n = 26, mean ± SD: age 28 ± 8 yr) took part in either: 1) two separate energy-matched cycling bouts: one of moderate intensity (MOD) and a bout of high intensity interval exercise (HIIE) or 2) an eccentric-based resistance exercise protocol (RES). Alterations in plasma (study 1) and serum (study 2) peroxiredoxin (PRDX)-2, PRDX-4, superoxide dismutase-3 (SOD3), thioredoxin (TRX-1), TRX-reductase and interleukin (IL)-6 were assessed before and at various timepoints after exercise. There was a significant increase in SOD3 (+1.5 ng/mL) and PRDX-4 (+5.9 ng/mL) concentration following HIIE only, peaking at 30- and 60-min post-exercise respectively. TRX-R decreased immediately and 60 min following HIIE (-7.3 ng/mL) and MOD (-8.6 ng/mL), respectively. In non-resistance trained men, no significant changes in redox enzyme concentrations were observed up to 48 h following RES, despite significant muscle damage. IL-6 concentration increased in response to all trials, however there was no significant relationship between absolute or exercise-induced changes in redox enzyme concentrations. These results collectively suggest that HIIE, but not MOD or RES increase the extracellular concentration of PRDX-4 and SOD3. Exercise-induced changes in redox enzyme concentrations do not appear to directly relate to systemic changes in IL-6 concentration.NEW & NOTEWORTHY Two studies were conducted to characterize changes in redox enzyme concentrations after single bouts of exercise to investigate the emerging association between extracellular redox enzymes and inflammation. We provide evidence that SOD3 and PRDX-4 concentration increased following high-intensity aerobic but not eccentric-based resistance exercise. Changes were not associated with IL-6. The results provide a platform to investigate the utility of SOD3 and PRDX-4 as biomarkers of oxidative stress following exercise.

The Beneficial Effects of Lactobacillus plantarum PS128 on High-Intensity, Exercise-Induced Oxidative Stress, Inflammation, and Performance in Triathletes

A triathlon, which consists of swimming, bicycling, and running, is a high-intensity and long-term form of exercise that can cause injuries such as muscular damage, inflammation, oxidative stress, and energy imbalance. Probiotics are thought to play an important role in disease incidence, health promotion, and nutrient metabolism, but only a few studies have focused on physiological adaptations to exercise in sports science. Previous studies indicated that Lactobacillus supplementation could improve oxidative stress and inflammatory responses. We investigate the effects of Lactobacillus plantarum PS128 supplementation on triathletes for possible physiological adaptation. The triathletes were assigned to one of two groups with different exercise intensity stimulations with different time-points to investigate the effects of body compositions, inflammation, oxidative stress, performance, fatigue, and injury-related biochemical indices. L. plantarum PS128 supplementation, combined with training, can significantly alleviate oxidative stress (such as creatine kinase, Thioredoxin, and Myeloperoxidase indices) after a triathlon (p < 0.05). This effect is possibly regulated by a 6–13% decrease of indicated pro-inflammation (TNF-α, IL-6, and IL-8) cytokines (p < 0.05) and 55% increase of anti-inflammation (IL-10) cytokines (p < 0.05) after intensive exercise stimulation. In addition, L. plantarum PS128 can also substantially increase 24–69% of plasma-branched amino acids (p < 0.05) and elevate exercise performance, as compared to the placebo group (p < 0.05). In conclusion, L. plantarum PS128 may be a potential ergogenic aid for better training management, physiological adaptations to exercise, and health promotion.

Changes in blood biochemical markers before, during, and after a 2-day ultramarathon

We studied changes in blood markers of 18 nonprofessional, middle-aged runners of a 2-day, 130 km ultramarathon. Blood was sampled at baseline, after the goals on the first and second day, and at three time points (1, 3, and 5/6 days) after the race. Blood indices showed three patterns. First pattern indices showed essentially no changes after the two goals and after the race, including red blood cell indices, gamma-glutamyl transferase, and tumor necrosis factor-α. Second pattern markers, including the majority of indices, were elevated during the race (and also after the race for some parameters) and then returned to baseline afterward, including hemolysis/red blood cell destruction markers (indirect bilirubin) and an iron reservoir index (ferritin), muscle damage parameters (uric acid, creatine kinase, lactate dehydrogenase, and aspartate aminotransferase), renal function markers (creatinine and blood urea nitrogen), liver injury index (alanine aminotransferase), lipid metabolism indices (free fatty acid), reactive oxygen species and inflammation parameters (white blood cells, interleukin-6, and C-reactive protein), and energy production and catecholamines (adrenaline, noradrenaline, and dopamine). Third pattern index of a lipid metabolism marker – triglyceride – decreased during the race periods and started returning to baseline from then onward. Some hormonal markers such as insulin, leptin, and adiponectin showed unique patterns. These findings appeared informative for nonprofessional athletes to know about an optimal physical activity level, duration, and total exercise for elevating physical performance and monitoring physical/mental conditioning as well as for prevention of overtraining and physical injuries.

Monitoring changes in thioredoxin and over-oxidised peroxiredoxin in response to exercise in humans

INTRODUCTION

Peroxiredoxin (PRDX) and thioredoxin (TRX) are antioxidant proteins that control cellular signalling and redox balance, although their response to exercise is unknown. This study aimed to assess key aspects of the PRDX-TRX redox cycle in response to three different modes of exercise.

METHODS

Healthy males (n = 10, mean ± SD: 22 ± 3 yrs) undertook three exercise trials on separate days: two steady-state cycling trials at moderate (60% [Formula: see text]O2MAX; 27 min, MOD) and high (80% [Formula: see text]O2MAX; 20 min, HIGH) intensities, and a low-volume high-intensity interval training trial (10 × 1 min 90% [Formula: see text]O2MAX, LV-HIIT). Peripheral blood mononuclear cells were assessed for TRX-1 and over-oxidised PRDX (isoforms I-IV) protein expression before, during, and 30 min following exercise (post + 30). The activities of TRX reductase (TRX-R) and the nuclear factor kappa B (NF-κB) p65 subunit were also assessed.

RESULTS

TRX-1 increased during exercise in all trials (MOD, + 84.5%; HIGH, + 64.1%; LV-HIIT, + 205.7%; p < 05), whereas over-oxidised PRDX increased during HIGH only (MOD, - 28.7%; HIGH, + 202.9%; LV-HIIT, - 22.7%; p < .05). TRX-R and NF-κB p65 activity increased during exercise in all trials, with the greatest response in TRX-R activity seen in HIGH (p < 0.05).

DISCUSSION

All trials stimulated a transient increase in TRX-1 protein expression during exercise. Only HIGH induced a transient over-oxidation of PRDX, alongside the greatest change in TRX-R activity. Future studies are needed to clarify the significance of heightened peroxide exposure during continuous high-intensity exercise and the mechanisms of PRDX-regulatory control.

The thioredoxin system as a therapeutic target in human health and disease

The thioredoxin (Trx) system comprises Trx, truncated Trx (Trx-80), Trx reductase, and NADPH, besides a natural Trx inhibitor, the thioredoxin-interacting protein (TXNIP). This system is essential for maintaining the balance of the cellular redox status, and it is involved in the regulation of redox signaling. It is also pivotal for growth promotion, neuroprotection, inflammatory modulation, antiapoptosis, immune function, and atherosclerosis. As an ubiquitous and multifunctional protein, Trx is expressed in all forms of life, executing its function through its antioxidative, protein-reducing, and signal-transducing activities. In this review, the biological properties of the Trx system are highlighted, and its implications in several human diseases are discussed, including cardiovascular diseases, heart failure, stroke, inflammation, metabolic syndrome, neurodegenerative diseases, arthritis, and cancer. The last chapter addresses the emerging therapeutic approaches targeting the Trx system in human diseases.

Oxygen consumption and usage during physical exercise: the balance between oxidative stress and ROS-dependent adaptive signaling

The complexity of human DNA has been affected by aerobic metabolism, including endurance exercise and oxygen toxicity. Aerobic endurance exercise could play an important role in the evolution of Homo sapiens, and oxygen was not important just for survival, but it was crucial to redox-mediated adaptation. The metabolic challenge during physical exercise results in an elevated generation of reactive oxygen species (ROS) that are important modulators of muscle contraction, antioxidant protection, and oxidative damage repair, which at moderate levels generate physiological responses. Several factors of mitochondrial biogenesis, such as peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α), mitogen-activated protein kinase, and SIRT1, are modulated by exercise-associated changes in the redox milieu. PGC-1α activation could result in decreased oxidative challenge, either by upregulation of antioxidant enzymes and/or by an increased number of mitochondria that allows lower levels of respiratory activity for the same degree of ATP generation. Endogenous thiol antioxidants glutathione and thioredoxin are modulated with high oxygen consumption and ROS generation during physical exercise, controlling cellular function through redox-sensitive signaling and protein-protein interactions. Endurance exercise-related angiogenesis, up to a significant degree, is regulated by ROS-mediated activation of hypoxia-inducible factor 1α. Moreover, the exercise-associated ROS production could be important to DNA methylation and post-translation modifications of histone residues, which create heritable adaptive conditions based on epigenetic features of chromosomes. Accumulating data indicate that exercise with moderate intensity has systemic and complex health-promoting effects, which undoubtedly involve regulation of redox homeostasis and signaling.

A phase I trial of PX-12, a small-molecule inhibitor of thioredoxin-1, administered as a 72-hour infusion every 21 days in patients with advanced cancers refractory to standard therapy

PURPOSE

This phase I trial assessed the safety, dose limiting toxicity (DLT) and pharmacodynamics of PX-12 in adult patients with advanced refractory cancers.

METHODS

PX-12 was administered to sequential cohorts as a 72-h infusion utilizing a portable infusion pump on days 1, 2, and 3 of a 21-day cycle at a starting dose level of 300 mg/m(2)/day and escalating dose levels till DLT was observed. Plasma thioredoxin (Trx-1), vascular endothelial growth factor (VEGF) and FGF-2 (fibroblast growth factor) levels were measured predose and during infusion of PX-12.

RESULTS

Patients (n = 14) were enrolled to the following dose cohorts, 300 mg/m(2) (n = 3), 400 mg/m(2) (n = 10) and 500 mg/m(2) (n = 1). Common grade 1/2 toxicities included fatigue, taste alteration and odor caused by expired drug metabolite. DLTs were one episode each of grade 3 hypoxia at the 400 mg/m(2) and grade 3 reversible pneumonitis at the 500 mg/m(2) dose levels. Best response was stable disease in a patient with rectal cancer. Predose Trx-1 levels (n = 12) ranged from 5.1 to 30.0 ng/mL (median 12.6 ng/mL).

CONCLUSION

PX-12 administered at 400 mg/m(2)/day by 72-hour infusion appears safe and tolerable. Inhibition of thioredoxin is a strategy worth evaluation with next generation of inhibitors.

A randomized phase II study of PX-12, an inhibitor of thioredoxin in patients with advanced cancer of the pancreas following progression after a gemcitabine-containing combination

PURPOSE

This study evaluated PX-12, a novel small molecule inhibitor of the proto-oncogene (Trx-1), in patients with previously treated advanced pancreatic cancer (APC).

METHODS

PX-12 (54 or 128 mg/m²) was administered by 3-hour IV infusion daily × 5 days every 21 days (n = 17). Patients were randomized to either 54 or 128 mg/m² and then stratified based on CA 19-9 level (≥ 1,000 vs. < 1,000 U/ml) and SUV values on PET scans (≥ 7.0 vs. <7.0). The primary endpoint was based on a progression-free survival (PFS) at 4 months in ≥ 40% of patients, and required 40 patients in each arm. An amendment required elevated Trx-1 levels (> 18 ng/ml) as an entry criteria after the first 17 patients were accrued.

RESULTS

Plasma Trx-1 levels were elevated in 3/28 (11%) patients screened for study. The grade of the expired metabolite odor was higher in the 128 mg/m² arm. Therapy was well tolerated, and Grade ≥ 3 adverse events were uncommon. The best response was stable disease in 2 patients. There was no consistent decrease in SUV, Trx-1 levels or CA 19-9 levels with therapy. No patients had a PFS of >4 months. Median PFS and survival were 0.9 months (95% CI 0.5-1.2) and 3.2 months (95% CI 2.4-4.2), respectively.

CONCLUSIONS

Due to the lack of significant antitumor activity and unexpectedly low baseline Trx-1 levels, the study was terminated early. PX-12 does not appear to be active in unselected patients with previously treated APC.