Molecular mechanisms of exercise contributing to tissue regeneration

Physical activity has been known as an essential element to promote human health for centuries. Thus, exercise intervention is encouraged to battle against sedentary lifestyle. Recent rapid advances in molecular biotechnology have demonstrated that both endurance and resistance exercise training, two traditional types of exercise, trigger a series of physiological responses, unraveling the mechanisms of exercise regulating on the human body. Therefore, exercise has been expected as a candidate approach of alleviating a wide range of diseases, such as metabolic diseases, neurodegenerative disorders, tumors, and cardiovascular diseases. In particular, the capacity of exercise to promote tissue regeneration has attracted the attention of many researchers in recent decades. Since most adult human organs have a weak regenerative capacity, it is currently a key challenge in regenerative medicine to improve the efficiency of tissue regeneration. As research progresses, exercise-induced tissue regeneration seems to provide a novel approach for fighting against injury or senescence, establishing strong theoretical basis for more and more "exercise mimetics." These drugs are acting as the pharmaceutical alternatives of those individuals who cannot experience the benefits of exercise. Here, we comprehensively provide a description of the benefits of exercise on tissue regeneration in diverse organs, mainly focusing on musculoskeletal system, cardiovascular system, and nervous system. We also discuss the underlying molecular mechanisms associated with the regenerative effects of exercise and emerging therapeutic exercise mimetics for regeneration, as well as the associated opportunities and challenges. We aim to describe an integrated perspective on the current advances of distinct physiological mechanisms associated with exercise-induced tissue regeneration on various organs and facilitate the development of drugs that mimics the benefits of exercise.

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.

Ultra-Endurance Associated With Moderate Exercise in Rats Induces Cerebellar Oxidative Stress and Impairs Reactive GFAP Isoform Profile

Ultra-endurance (UE) race has been associated with brain metabolic changes, but it is still unknown which regions are vulnerable. This study investigated whether high-volume training in rodents, even under moderate intensity, can induce cerebellar oxidative and inflammatory status. Forty-five adult rats were divided into six groups according to a training period, followed or not by an exhaustion test (ET) that simulated UE: control (C), control + ET (C-ET), moderate-volume (MV) training and MV-ET, high-volume training (HV) and HV-ET. The training period was 30 (MV) and 90 (HV) min/day, 5 times/week for 3 months as a continuous running on a treadmill at a maximum velocity of 12 m/min. After 24 h, the ET was performed at 50% maximum velocities up to the animals refused to run, and then serum lactate levels were evaluated. Serum and cerebellar homogenates were obtained 24 h after ET. Serum creatine kinase (CK), lactate dehydrogenase (LDH), and corticosterone levels were assessed. Lipid peroxidation (LP), nitric oxide (NO), Interleukin 1β (IL-1β), and GFAP proteins, reduced and oxidized glutathione (GSH and GSSG) levels, superoxide dismutase (SOD) and catalase (CAT) activities were quantified in the cerebellum. Serum lactate concentrations were lower in MV-ET (∼20%) and HV-ET (∼40%) compared to the C-ET group. CK and corticosterone levels were increased more than ∼ twofold by HV training compared to control. ET increased CK levels in MV-ET vs. MV group (P = 0.026). HV induced higher LP levels (∼40%), but an additive effect of ET was only seen in the MV-ET group (P = 0.02). SOD activity was higher in all trained groups vs. C and C-ET (P < 0.05). CAT activity, however, was intensified only in the MV group (P < 0.02). The 50 kDa GFAP levels were enhanced in C-ET and MV-ET vs. respective controls, while 42 kDa (∼40%) and 39 kDa (∼26%) isoform levels were reduced. In the HV-ET group, the 50 KDa isoform amount was reduced ∼40-60% compared to the other groups and the 39 KDa isoform, increased sevenfold. LDH levels, GSH/GSSG ratio, and NO production were not modified. ET elevated IL-1β levels in the CT and MV groups. Data shows that cerebellar resilience to oxidative damage may be maintained under moderate-volume training, but it is reduced by UE running. High-volume training per se provoked systemic metabolic changes, cerebellar lipid peroxidation, and unbalanced enzymatic antioxidant resource. UE after high-volume training modified the GFAP isoform profile suggesting impaired astrocyte reactivity in the cerebellum.

Acute Effects of Triathlon Race on Oxidative Stress Biomarkers

The response to strenuous exercise was investigated by reactive oxygen species (ROS) production, oxidative damage, thiol redox status, and inflammation assessments in 32 enrolled triathlon athletes (41.9 ± 7.9 yrs) during Ironman® (IR), or half Ironman® (HIR) competition. In biological samples, inflammatory cytokines, aminothiols (glutathione (GSH), homocysteine (Hcy), cysteine (Cys), and cysteinylglycine (CysGly)), creatinine and neopterin, oxidative stress (OxS) biomarkers (protein carbonyl (PC), thiobarbituric acid-reactive substances (TBARS)), and ROS were assessed. Thirteen HIR and fourteen IR athletes finished the race. Postrace, ROS (HIR +20%; IR +28%; p < 0.0001), TBARS (HIR +57%; IR +101%), PC (HIR +101%; IR +130%) and urinary neopterin (HIR +19%, IR +27%) significantly (range p < 0.05-0.0001) increased. Moreover, HIR showed an increase in total Cys +28%, while IR showed total aminothiols, Cys, Hcy, CysGly, and GSH increase by +48, +30, +58, and +158%, respectively (range p < 0.05-0.0001). ROS production was significantly correlated with TBARS and PC (R 2 = 0.38 and R 2 = 0.40; p < 0.0001) and aminothiols levels (range R 2 = 0.17-0.47; range p < 0.01-0.0001). In particular, ROS was directly correlated with the athletes' age (R 2 = 0.19; p < 0.05), with ultraendurance years of training (R 2 = 0.18; p < 0.05) and the days/week training activity (R 2 = 0.16; p < 0.05). Finally, the days/week training activity (hours/in the last 2 weeks) was found inversely correlated with the IL-6 postrace (R 2 = -0.21; p < 0.01). A strenuous performance, the Ironman® distance triathlon competition, alters the oxidant/antioxidant balance through a great OxS response that is directly correlated to the inflammatory parameters; furthermore, the obtained data suggest that an appropriate training time has to be selected in order to achieve the lowest ROS production and IL-6 concentration at the same time.

Oxidative stress in asthma: Part of the puzzle

An imbalance between the production of reactive oxygen species and the capacity of antioxidant defense mechanisms favoring oxidants is called oxidative stress and is implicated in asthmatic inflammation and severity. Major reactive oxygen species that are formed endogenously include hydrogen peroxide, superoxide anion, hydroxyl radical, and hypohalite radical; and the major antioxidants that fight against the endogenous and environmental oxidants are superoxide dismutase, catalase, and glutathione. Despite the well-known presence of oxidative stress in asthma, studies that target oxidative burden using a variety of nutritional, pharmacological, and environmental approaches have generally been disappointing. In this review, we summarize the current knowledge on oxidative stress and antioxidant imbalance in asthma. In addition, we focus on possible biomarkers of oxidative stress in asthma and on current and future treatment strategies using the modulation of oxidative stress to treat asthma patients.

Untargeted Metabolomics Profiling of an 80.5 km Simulated Treadmill Ultramarathon

Metabolomic profiling of nine trained ultramarathon runners completing an 80.5 km self-paced treadmill-based time trial was carried out. Plasma samples were obtained from venous whole blood, collected at rest and on completion of the distance (post-80.5 km). The samples were analyzed by using high-resolution mass spectrometry in combination with both hydrophilic interaction (HILIC) and reversed phase (RP) chromatography. The extracted putatively identified features were modeled using Simca P 14.1 software (Umetrics, Umea, Sweden). A large number of amino acids decreased post-80.5 km and fatty acid metabolism was affected with an increase in the formation of medium-chain unsaturated and partially oxidized fatty acids and conjugates of fatty acids with carnitines. A possible explanation for the complex pattern of medium-chain and oxidized fatty acids formed is that the prolonged exercise provoked the proliferation of peroxisomes. The peroxisomes may provide a readily utilizable form of energy through formation of acetyl carnitine and other acyl carnitines for export to mitochondria in the muscles; and secondly may serve to regulate the levels of oxidized metabolites of long-chain fatty acids. This is the first study to provide evidence of the metabolic profile in response to prolonged ultramarathon running using an untargeted approach. The findings provide an insight to the effects of ultramarathon running on the metabolic specificities and alterations that may demonstrate cardio-protective effects.

Impact of the 24-h ultramarathon race on homocysteine, oxidized low-density lipoprotein, and paraoxonase 1 levels in professional runners

The impact of the 24-h ultramarathon race on homocysteine (Hcy) and oxidized low-density lipoprotein (oxLDL) levels, two well-recognized cardiovascular risk factors, has not been deeply investigated. Similarly, no information exists on paraoxonase 1 (PON1), an antioxidant enzyme associated with high-density lipoproteins, which may detoxify oxLDL and Hcy-thiolactone, hence preventing their proatherogenic action. Taking this into account, a competitive 24-h ultramarathon race was organized in Reggio-Emilia (Italy) recruiting professional runners (n = 14) from the Italian Ultramarathon and Trail Association. Blood samples were collected from each participant before, during (14 h), and immediately after (24 h) the competition, thus to monitor the serum changes in Hcy, oxLDL, and PON1 levels, as well as other oxidative stress-related parameters, namely reactive oxygen metabolites (ROM) and total antioxidant capacity (PAT). As a result, a significant PON1 increase was recorded after 14 h of racing that persisted until the end of the performance. The same trend was observed for PAT values, which positively correlated to PON1 levels (R = 0.643, P<0.001). Hcy, oxLDL, and ROM remained almost unchanged throughout the competition. In conclusion, the present study suggested a protective role of PON1 in sustaining the antioxidant defense system and contrasting lipoprotein oxidative modifications over the 24-h race, and did not specifically evidence either Hcy or oxLDL accumulation in such challenging sporting events.

High Volume Exercise Training in Older Athletes Influences Inflammatory and Redox Responses to Acute Exercise

To examine whether the volume of previous exercise training in older athletes influences inflammatory, redox, and hormonal profiles, 40 trained marathon runners were divided into higher-volume (HVG, ∼480 min/week) and lower-volume groups (LVG, ∼240 min/week). Plasma inflammatory proteins, redox biomarkers, salivary testosterone, and cortisol were assessed at restand following two maximal acute exercise bouts. At rest, the LVG exhibited higher CRP, higher protein carbonyls, and lower SOD activity compared to the HVG (p's < .05). In response to exercise, TNF-α declined similarly in both groups whereas CRP increased differentially (+60% LVG; +24% HVG; p's < .05). Protein carbonyls decreased and thiols increased similarly in both groups, but SOD declined differentially between groups (-14% LVG; -20% HVG; p's < .05). Salivary testosterone decreased similarly in both groups, whereas cortisol did not change. A higher volume of training is associated with favorable inflammatory and redox profiles at rest, perhaps mediated by small inflammatory responses to acute exercise.

Variations in Oxidative Stress Levels in 3 Days Follow-up in Ultramarathon Mountain Race Athletes

Spanidis, Y, Stagos, D, Orfanou, M, Goutzourelas, N, Bar-or, D, Spandidos, D, and Kouretas, D. Variations in oxidative stress levels in 3 days follow-up in ultramarathon mountain race athletes. J Strength Cond Res 31(3): 582-594, 2017-The aim of the present study was the monitoring of the redox status of runners participating in a mountain ultramarathon race of 103 km. Blood samples from 12 runners were collected prerace and 24, 48, and 72 hours postrace. The samples were analyzed by using conventional oxidative stress markers, such as protein carbonyls (CARB), thiobarbituric acid reactive substances (TBARS), total antioxidant capacity (TAC) in plasma, as well as glutathione (GSH) levels and catalase (CAT) activity in erythrocytes. In addition, 2 novel markers, the static oxidation-reduction potential marker (sORP) and the capacity oxidation-reduction potential (cORP), were measured in plasma. The results showed significant increase in sORP levels and significant decrease in cORP and GSH levels postrace compared with prerace. The other markers did not exhibit significant changes postrace compared with prerace. Furthermore, an interindividual analysis showed that in all athletes but one sORP was increased, whereas cORP was decreased. Moreover, GSH levels were decreased in all athletes at least at 2 time points postrace compared with prerace. The other markers exhibited great variations between different athletes. In conclusion, ORP and GSH markers suggested that oxidative stress has existed even 3 days post ultramarathon race. The practical applications from these results would be that the most effective markers for short-term monitoring of ultramarathon mountain race-induced oxidative stress were sORP, cORP, and GSH. Also, administration of supplements enhancing especially GSH is recommended during ultramarathon mountain races to prevent manifestation of pathological conditions.

Oxidative Stress Assessment in Response to Ultraendurance Exercise: Thiols Redox Status and ROS Production according to Duration of a Competitive Race

Purpose. Response to an ultraendurance competitive race on thiols redox status, reactive oxygen species (ROS) production, and oxidative stress (OxS) was investigated according to duration. Methods. Twenty-four elite runners were examined: six completed 50 km and eighteen 100 km. Blood and urine samples were collected before and immediately after the race. Erythrocytes and plasma aminothiols by high-performance liquid chromatography, total antioxidant capacity (TAC), and OxS biomarkers (protein carbonyl (PC), thiobarbituric acid-reactive substances (TBARS), 8-isoprostane (8-iso-PGF2α), and 8-OH-2-deoxyguanosine (8-OH-dG)) by immunoenzymatic assays and ROS production by Electron Paramagnetic Resonance were assessed. Results. Significant increases (P between <0.05 and <0.0001) were recorded in plasma total and oxidized aminothiols concentration and TAC (P < 0.0001) only after 100 km: plasmatic (ROS production (+12 versus +29%), PC (+54 versus +115%), and TBARS (+28 versus +55%)) and urinary (8-OH-dG.creatinine⁻¹ (+71 versus +158%) and 8-iso-PGF2α.creatinine⁻¹ (+43 versus +135%)) concentrations for 50 and 100 km (duration 4 h 3′ versus 8 h 42′), respectively. Conclusion. Very prolonged ultraendurance exercise causes an increase in ROS production and OxS depending on specific biomarker examined but always linearly and directly related to exercise duration. Redox status of erythrocytes was preserved. A relationship between running performance and both prerace ROS production and antioxidant-redox status was found in 100 km race.

Is immunosenescence influenced by our lifetime "dose" of exercise?

The age-associated decline in immune function, referred to as immunosenescence, is well characterised within the adaptive immune system, and in particular, among T cells. Hallmarks of immunosenescence measured in the T cell pool, include low numbers and proportions of naïve cells, high numbers and proportions of late-stage differentiated effector memory cells, poor proliferative responses to mitogens, and a CD4:CD8 ratio <1.0. These changes are largely driven by infection with Cytomegalovirus, which has been directly linked with increased inflammatory activity, poor responses to vaccination, frailty, accelerated cognitive decline, and early mortality. It has been suggested however, that exercise might exert an anti-immunosenescence effect, perhaps delaying the onset of immunological ageing or even rejuvenating aged immune profiles. This theory has been developed on the basis of evidence that exercise is a powerful stimulus of immune function. For example, in vivo antibody responses to novel antigens can be improved with just minutes of exercise undertaken at the time of vaccination. Further, lymphocyte immune-surveillance, whereby cells search tissues for antigens derived from viruses, bacteria, or malignant transformation, is thought to be facilitated by the transient lymphocytosis and subsequent lymphocytopenia induced by exercise bouts. Moreover, some forms of exercise are anti-inflammatory, and if repeated regularly over the lifespan, there is a lower morbidity and mortality from diseases with an immunological and inflammatory aetiology. The aim of this article is to discuss recent theories for how exercise might influence T cell immunosenescence, exploring themes in the context of hotly debated issues in immunology.

Effects of Mountain Ultra-Marathon Running on ROS Production and Oxidative Damage by Micro-Invasive Analytic Techniques

PURPOSE

Aiming to gain a detailed insight into the physiological mechanisms involved under extreme conditions, a group of experienced ultra-marathon runners, performing the mountain Tor des Géants® ultra-marathon: 330 km trail-run in Valle d'Aosta, 24000 m of positive and negative elevation changes, was monitored. ROS production rate, antioxidant capacity, oxidative damage and inflammation markers were assessed, adopting micro-invasive analytic techniques.

METHODS

Forty-six male athletes (45.04±8.75 yr, 72.6±8.4 kg, 1.76±0.05 m) were tested. Capillary blood and urine were collected before (Pre-), in the middle (Middle-) and immediately after (Post-) Race. Samples were analyzed for: Reactive Oxygen Species (ROS) production by Electron Paramagnetic Resonance; Antioxidant Capacity by Electrochemistry; oxidative damage (8-hydroxy-2-deoxy Guanosine: 8-OH-dG; 8-isoprostane: 8-isoPGF2α) and nitric oxide metabolites by enzymatic assays; inflammatory biomarkers (plasma and urine interleukin-6: IL-6-P and IL-6-U) by enzyme-linked immunosorbent assays (ELISA); Creatinine and Neopterin by HPLC, hematologic (lactate, glucose and hematocrit) and urine parameters by standard analyses.

RESULTS

Twenty-five athletes finished the race, while twenty-one dropped out of it. A significant increase (Post-Race vs Pre) of the ROS production rate (2.20±0.27 vs 1.65±0.22 μmol.min-1), oxidative damage biomarkers (8-OH-dG: 6.32±2.38 vs 4.16±1.25 ng.mg-1 Creatinine and 8-isoPGF2α: 1404.0±518.30 vs 822.51±448.91 pg.mg-1Creatinine), inflammatory state (IL-6-P: 66.42±36.92 vs 1.29±0.54 pg.mL-1 and IL-6-U: 1.33±0.56 vs 0.71±0.17 pg.mL1) and lactate production (+190%), associated with a decrease of both antioxidant capacity (-7%) and renal function (i.e. Creatinine level +76%) was found.

CONCLUSIONS

The used micro-invasive analytic methods allowed us to perform most of them before, during and immediately after the race directly in the field, by passing the need of storing and transporting samples for further analysis. Considered altogether the investigated variables showed up that exhaustive and prolonged exercise not only promotes the generation of ROS but also induces oxidative stress, transient renal impairment and inflammation.